CA2092448A1 - Heat cured silicone rubber compositions containing a potassium aluminosilicate filler which provides resistance to hydrocarbon oils and adjustable shrinkage - Google Patents
Heat cured silicone rubber compositions containing a potassium aluminosilicate filler which provides resistance to hydrocarbon oils and adjustable shrinkageInfo
- Publication number
- CA2092448A1 CA2092448A1 CA002092448A CA2092448A CA2092448A1 CA 2092448 A1 CA2092448 A1 CA 2092448A1 CA 002092448 A CA002092448 A CA 002092448A CA 2092448 A CA2092448 A CA 2092448A CA 2092448 A1 CA2092448 A1 CA 2092448A1
- Authority
- CA
- Canada
- Prior art keywords
- vinyl
- units
- parts
- weight
- silicone rubber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06E—OPTICAL COMPUTING DEVICES; COMPUTING DEVICES USING OTHER RADIATIONS WITH SIMILAR PROPERTIES
- G06E1/00—Devices for processing exclusively digital data
- G06E1/02—Devices for processing exclusively digital data operating upon the order or content of the data handled
- G06E1/04—Devices for processing exclusively digital data operating upon the order or content of the data handled for performing computations using exclusively denominational number representation, e.g. using binary, ternary, decimal representation
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06E—OPTICAL COMPUTING DEVICES; COMPUTING DEVICES USING OTHER RADIATIONS WITH SIMILAR PROPERTIES
- G06E3/00—Devices not provided for in group G06E1/00, e.g. for processing analogue or hybrid data
- G06E3/001—Analogue devices in which mathematical operations are carried out with the aid of optical or electro-optical elements
- G06E3/005—Analogue devices in which mathematical operations are carried out with the aid of optical or electro-optical elements using electro-optical or opto-electronic means
Abstract
PATENTS
ABSTRACT OF THE DISCLOSURE
Heat cured silicone rubber compositions which contain a potassium aluminosilicate filler exhibit improved resistance to hydrocarbon oils. The potassium aluminosilicate filler has an average surface area of between about 5.0 and about 6.50 m2/g, an average particle diameter of between about 1.0 and about 20.0 micrometers, and an average particle thickness of between about 0.5 and 1.0 micrometers. The filler improves retention of physical properties and resistance to swelling in hot hydrocarbon oils in a wide variety of siloxane compositions.
ABSTRACT OF THE DISCLOSURE
Heat cured silicone rubber compositions which contain a potassium aluminosilicate filler exhibit improved resistance to hydrocarbon oils. The potassium aluminosilicate filler has an average surface area of between about 5.0 and about 6.50 m2/g, an average particle diameter of between about 1.0 and about 20.0 micrometers, and an average particle thickness of between about 0.5 and 1.0 micrometers. The filler improves retention of physical properties and resistance to swelling in hot hydrocarbon oils in a wide variety of siloxane compositions.
Description
2~9~48 ,~
PATEN'rS
HE:AT CURED SILICON13 RUBBER COMPOSITIONS ':
TAINING A POT~5SIUM AII~IINIOSILICATE FII,LE:R
~HICH PROVIl)ES RE:SISTANCE TO HYDROCARE~ON OILS .;
AND ADJllSq~A~LE SHRINlCAGE 1:
~!lQ~E~
Th~ pre~en~ invsntion ~elatea to hea~ cured sillcon~ rubber compooition~ h~ving improved :resl~tance to shrinkage and hydroc~rbon oil~. More p~rticularly, 5 ths invention relat~ to he~t cured ~ ~ licone rubber compositions exh~ biting improved resi~tance to :::
hydrocarbon oil~. The s:ompo~itiorls contain a potas~ium aluminosiliGa e fillar having ~ ~pecific s?lrfac~ area, particle~ diame~er, and particle th~ckne~
, ' :, ', ' :` "
,, .:
~ J9~l141 8 r~
- 2 P~NTS
60~ 15?4 BAC~GROUND OF THE I ~ NTION
Heat curable silicone rubber composition are known for their ability to r~ist chang~ at elevated temperature and expo~ure to adver~e conditions over S extendQd periods of tLme. Silicone rubber comp~ ition for u~e in gasketin~ application~ require good ~ar and ten~ile ~txen~th and reduced compre~sion set properties.
He~t cured silicone rubber compo~ition~ us~d in automotive ga~keting application~ ~UBt al80 have a strong resi~tance to hydrocarbon oil~, e~pecially at high temp~ratures.
Silicone rubber compo~itions, like most ela~o~ric materials, tend ~o shrink a~ a function o~
t~mper~ture and the th~rmal expan3ion of the m~te~Lal.
Shrinka~e i3 also dependent upon chemical change and the 10~8 o~ volatil~s during curing. Dif~erent combinstlons o~ pQlymers, fillers and molding t~mperature~ are used in attempts to control th~ degree of shrinkage.
A cur~d pro~uct should have the ~ame dlmQnsions a~
its mold wh~n both are at a curing tempera~ure. The part, however, shrinks up~n cooling. It i8 difficult , , . i 20~2'1~ ~
PATEN'rS
HE:AT CURED SILICON13 RUBBER COMPOSITIONS ':
TAINING A POT~5SIUM AII~IINIOSILICATE FII,LE:R
~HICH PROVIl)ES RE:SISTANCE TO HYDROCARE~ON OILS .;
AND ADJllSq~A~LE SHRINlCAGE 1:
~!lQ~E~
Th~ pre~en~ invsntion ~elatea to hea~ cured sillcon~ rubber compooition~ h~ving improved :resl~tance to shrinkage and hydroc~rbon oil~. More p~rticularly, 5 ths invention relat~ to he~t cured ~ ~ licone rubber compositions exh~ biting improved resi~tance to :::
hydrocarbon oil~. The s:ompo~itiorls contain a potas~ium aluminosiliGa e fillar having ~ ~pecific s?lrfac~ area, particle~ diame~er, and particle th~ckne~
, ' :, ', ' :` "
,, .:
~ J9~l141 8 r~
- 2 P~NTS
60~ 15?4 BAC~GROUND OF THE I ~ NTION
Heat curable silicone rubber composition are known for their ability to r~ist chang~ at elevated temperature and expo~ure to adver~e conditions over S extendQd periods of tLme. Silicone rubber comp~ ition for u~e in gasketin~ application~ require good ~ar and ten~ile ~txen~th and reduced compre~sion set properties.
He~t cured silicone rubber compo~ition~ us~d in automotive ga~keting application~ ~UBt al80 have a strong resi~tance to hydrocarbon oil~, e~pecially at high temp~ratures.
Silicone rubber compo~itions, like most ela~o~ric materials, tend ~o shrink a~ a function o~
t~mper~ture and the th~rmal expan3ion of the m~te~Lal.
Shrinka~e i3 also dependent upon chemical change and the 10~8 o~ volatil~s during curing. Dif~erent combinstlons o~ pQlymers, fillers and molding t~mperature~ are used in attempts to control th~ degree of shrinkage.
A cur~d pro~uct should have the ~ame dlmQnsions a~
its mold wh~n both are at a curing tempera~ure. The part, however, shrinks up~n cooling. It i8 difficult , , . i 20~2'1~ ~
- 3 _ PAT~NTS
to precisely ad~ust the formulation of the ela3tom~ric material such that the optimum combination of proper-ties and shrinkage is provided. The cost as~ociated with manufacturing a mold which provides acceptable measured tolerance~ of cured parts is high. A
convenient and beneficial additive ~o ad~u~t ~hrinkage is thus de~irable.
Although heat curable silicone rubber compositions ha~ing good tear strength, tensile s~rength and low compre~sion se~ propertie~ are known in the art, compo~ition~ for use in various automotive gasketing application~ currently lack a combination of these properties along with excellent oil re~i~tance and ad~u~table shrinkage. It i8 desirable to pro~ide heat cured silicone elastomer compositions having the properties and durability that enable their u~e in v~rious automotive ga~keting applications.
SUMMARY OF THE INvENrIoN
The presQnt invention i8 based upon the dlscovery that a better balance o~ propertie~ necessary ~or a composition used in automotive gasketing applications can be achieved by adding a potas~ium alumino~ilicate filler to a heat curable silicone rubber ela~tomer.
According to the present invQntion, compositions can be produced which, upon heat curing, exhibit excellent oil resistance propertie~. The filler may be used in siloxane composition~ which may contain an MQ
re~in component. The pre~ent invention can be exemplified, but should in no way be con~idered limited to, the following composition~ which are in3tructive in the use of pota~sium aluminosilicate fillers for achieving excellent resi~tance to hydrocarbon oil~.
2~2~
.
to precisely ad~ust the formulation of the ela3tom~ric material such that the optimum combination of proper-ties and shrinkage is provided. The cost as~ociated with manufacturing a mold which provides acceptable measured tolerance~ of cured parts is high. A
convenient and beneficial additive ~o ad~u~t ~hrinkage is thus de~irable.
Although heat curable silicone rubber compositions ha~ing good tear strength, tensile s~rength and low compre~sion se~ propertie~ are known in the art, compo~ition~ for use in various automotive gasketing application~ currently lack a combination of these properties along with excellent oil re~i~tance and ad~u~table shrinkage. It i8 desirable to pro~ide heat cured silicone elastomer compositions having the properties and durability that enable their u~e in v~rious automotive ga~keting applications.
SUMMARY OF THE INvENrIoN
The presQnt invention i8 based upon the dlscovery that a better balance o~ propertie~ necessary ~or a composition used in automotive gasketing applications can be achieved by adding a potas~ium alumino~ilicate filler to a heat curable silicone rubber ela~tomer.
According to the present invQntion, compositions can be produced which, upon heat curing, exhibit excellent oil resistance propertie~. The filler may be used in siloxane composition~ which may contain an MQ
re~in component. The pre~ent invention can be exemplified, but should in no way be con~idered limited to, the following composition~ which are in3tructive in the use of pota~sium aluminosilicate fillers for achieving excellent resi~tance to hydrocarbon oil~.
2~2~
.
- 4 _ PA~ENTS
~QE~L9~
A pota~sium aluminosllicate filler i~ added to a blend compri~ing at least one organopoly~iloxane gum, an optional MQ or ~ D-vinyl Q re~in or blends thereof, a silica filler, ~n optional vinyl~on-chain siloxane gum, and an organohydrogen~ilo~ane cro~s-linking agent.
The mixture produce~ a ~ilicone elastomer which is heat curable in the presence of a catalyst.
In one group of composition~, blends are formulated which comprise 100 part~ by weight of a polymer 8y8t~m. The polymer sy~tem compri~ at lea~t one dior~anopoly~iloxane having a visco~ity of about 3,000,0Q0 to about 100,000,000 centipoise ~ Cp8 ) at 25C, herein described a~ Components (A)-(D~, and up to 30 parts by weight, based on 100 part~ by weight of the at least one diorganopolysiloxane gum, of an MQ or M D-vinyl Q resin copolymer or resin copolymer blend, Component (F).
The organopolysiloxane gum Co~ponent~ (A)-(D) may be used in various combinations or ~eparately. The gu~
or gum~ should each have a viscosity o~ up to about 100~000,000 Cp8 at 25C. More preferab}y, gum components are u~ed which have visco~ities of from about 3,000,000 to about 100,000,000 Cp8 at 25C.
The gum vr gums may be (A) free o~ vinyl groups, (B) vinyl-stopped, (C~ have vinyl-on-chain, or (D) have both vinyl end stops and vinyl-on-chain. For purpo3es of cl~rificatio~, Component~ (A)~(D) will be explainad in qreater detail below. The polymsr sy~tems of the compo~itions of the pre~ent invention are defined a~
100 parts by weight. Any of the polymers t~)-(D) may make up the 0ntire weight of the polymer sy~tem, a portion of the entire weightl or may be completely :, ~, ', 2~2~'18 , ~, _ 5 _ PATENTS
60$I-1524 absent from the polymer ~ystem. The polymer sy~tem al80 include~ the re~in, Component ~F~, if used.
Up to 100 p~r~s by weight of the polymer system may be Component (A), ~n organopolysiloxane substantially free of vinyl and having a vi8c08ity of from abut 3,000,000 to about 100,000,000 cps at 25C.
Alternatively, Component (~) can comprise a mixture of such organopolysiloxanes.
Up to 100 parts by weiyht of the polymer system may be Component 5B), a vinyl chain-~topped organopolysiloxane, substantially free of vinyl-on-chain, having a viscosity of from about 3,000,000 to about 100,000,000 Cp8 ~t 25 C . Alternatively, Component ~B) can comprise a mixtura of such organopolysiloxanes.
Up to about 100 parts by weight of thP polymer 8y8tem may be Component (C), a vinyl-on-chain organopolysiloxane, free of ~inyl chain stops, having a vinyl content of about 5x10-3 to about 5 wei~ht percent and a vi8c08ity of from about 3,000,000 to about 100,000,000 Cp8 at 25C. Altern~ti~ely, Component (C) may comprise mixtures of ~uch organopolysiloxanes.
Up to about 100 parts by weight of the polymer sy~tem may be Component (D), a vinyl chaln-stopped, vinyl-on-chain organopolysiloxane having a vinyl content of about 5x10-3 to about 5 weight perc~nt.
Alternatively, Component (D) may compriRe mixture of ~uch organopolysiloxanes.
The resin copolymer ~F) may compri~e (1~ R3SiO1J2 monofunctional units (M units) and SiO2 ~u~dri-functional unit~ (Q units), where each R i8 independently selected from the group con~isting of ' ~ ' .
2~2~
` ~ --vinyl radicals and monovalent hydrocarbon radicals ree of aliphatic unsaturation. The ratio of M units to Q
unit~ ranges from about 0.5:1 to abou~ 1.5 5 1 ~ wherein about O.S to about 10.0 w~ight percent are vinyl groups.
Alternatively, the organopolysiloxane resin, Component (F), may comprise (2) an organopolysilo~ane re~in copolymer containing M and Q units as aforesaid and ~25iO2~2 difunctional (D units) where each R i~i indep~ndently selected from the group consi~ting of vinyl radical~ and monovalent hydrocarbon radicals free of aliphatic un~aturation. Each M unit may represent M or M' e.g. M-vinyl units, and each D unit may represent D or D~ e.g. D-vinyl unit~. The ratio of M
15 units to Q units i3 from 0 . 5 :1 to about 1. 5 :1 and the D unit~ are pre~ent in an amount of from about 1 to 70 mol percent based upon the total numbsr of mol~ of siloxy units in the copolymer. The xesinouR copolymer contains from about 0.5 to abou~ lO.0 weight percent vinyl groups. The organopolysiloxane resin copolymer may con~ain mixtureR of the MQ and the M D--vinyl Q, xesin~.
In addition to the exemplary polymer ~ystem made up of components ~A)- (F), and based upon 100 par~s by 25 weight of t:he polymer 5y8tem, the Compositions of ~he present invention also contain:
(G) from about 1 to about 50 par~ by weight, ba~ed upon the polymer system, of a pota~ium aluminosiilicate filler having a laminar strus::ture, a surfaee area of between about 5.0 and about 6.50 square m~ter3 per gram, an average particle diametor of from about 1 . 0 to about 20. 0 micrometers, and an average :, : . .. .:
. ~, .. .. .
~)92 r~
particle thicknes~ o~ from about 0.5 to about 1.0 micrometer~;
(H) up to about 200 parts based upon the polymer system of a finely divided silica filler;
(I) up to about 100 part~ based upon the polymer 8y8tem of a vinyl-stopped, ~inyl-on-ch~in polymer ha~ing from about 5x10-3 to about 5 weight percent vinyl; and (J) a random copolymer formed of a polydimethyl ~iloxane (P~MS) and a pol~methyl hydrogen siloxane (PMHS) having the forms R3SiO(SiORHSiOR2)XSiR~
wherein each R i8 independently chosen from a hydrogen or monovalent hydrocar~on xadical frea of aliphatic unsaturation containing 1 to about 8 carbon atoms, and x ranges from about 2 to about 100. In the present invention, th~ hydride i8 pr~ent in an amount ranging from about 0.1 to 10 part~ by weight ba~ed on the polymer ~ystem, preferably 0.5 to ~, and more preferably O~fl to 2.5 part3 by weight. When a hydride agent is employed, a platinum catAlyst may be ~ubstituted for the peroxide cataly~t to cure the compo~ition. In Component (J) x may vary ~o that (J) hax a viscosity ranging from about 5 to 500 cps, preferably from about 10 to about 100 cp~ and more preferabiy froM about 10 to 50 Cp8 at 25C.
In order to impro~e properties or processing, the compo~ition may al~o contain:
(R) up to about 2 part~ by weight of a t~tramethyl-divinyl ~ilazane ba~ed upon the polymer 8y8tem, and .~ ,,, . :
,, ~ .;
2a~2~l~s - 8 - PA~EN~S
(L) up to about 10 parts by weight ba~ed upon the polymer ~ystem of a processing aid ~ompriRing low vi~cosity silanol stopped siloxane fluid of from about 3 to about 500 centipoise at 25~C, or a dimethyl trimethoxy qiloxane polymer, or similar co~positions such a~ silanol or methoxy fluids of other visco~itie~.
Additionally, a cyclic methyl tetramer at about 15 to about ~0 percent by weigh~ based upon the weight of the filler (H~ may be used to treat the filler (H) prior to compounding.
A small amount of water may also be added to inCrQa~e the proceq~ibility of thQ blend. If usedr only up to about 0.1 parts by weight water based on the polymer system is u~ually employed.
lS In addition to the foregoing, a heat aging Component (M) such as fumed TiO2, iron octoate, Ce(OH)~
or mixtures thereof, may be present in rslatively small amounts, e.g., up to 2 parts by weight ba~ed upon the polymer 8y8tem. In the ex2mples below thç h~at aging component consists of 33 weight percent TiO2, 5 weight percent iron octoate solution ~which comprise~ about 12 weight psrcent iron in mineral 8pirit9 ), 10 wçiqht percent treated fumed silica (160 m2/g), and 50 wei~ht percent of an 800 penetratio~ vinyl-~topped, vinyl-on-chain gum.
An acid acceptor, Componenk (N), may al80 be addedto soak up acid. Thi~ acid could othexwi~e cau~e clea~aga of the product matrix. In one embodiment, ~N) compri~2s a masterbatch of about 25% MgO in a vinyl ~iloxane polymer.
~ he heat curable compositions of the pre~ent invention pro~ide heat cured silicone elastomer3 having good shrinkage 2nd uil resiqtance. ~hesç properties - ., . - ., ~ . , .. . . . ..
2 ~
~ 9 _ PA~ENTS
~Q~l~
are exhibited throughout extended p~riod3 of use at high temperatures making these compo8ition~ u9eful in automotiv~ gasketing applications.
DESCRIP~rION OF ?HE.INVENTION
Th2 composition~ of the pre~ent invention contain 100 parts by weight of a polymer system made up of:
a polydiorgano~iloxane gum having a visco~ity of about 3,000,000 to 100,000,000 Cp8 at 25C or blends of such gums, some or all of which may be vinyl-containing, described herein as Co~ponents (A)-(D);
and (F) an optional organopolysiloxane re~in of the ~Q or M D-vinyl Q types.
In addition to the exemplary polymer ~ys~em made up of Components (A)-(F), the co~positions of the present invention also contain:
(G) a pota~sium aluminosilicat~ fill~r having a laminar structure; ~H) a finely divided silica filler;
(I) an optional vinyl-on-chain ~iloxane gum; and (J) an organohydrogen~iloxane cros~-linking agent.
~0 Combinations o~ variou~ other component~ a~ described herein may also be added.
Component (G) is a potassium ~lumino~ilicate filler haviny a laminar structure. The filler i8 mixed with a siloxane composition in amounts from about 1 to about 50 parts by weight based on total weight of Component~ (A)-[L) described herein. Preferably, the filler i8 added in an amount between about 10 and about 40 parts by weight, more preferably from about 15 to about 30. The filler ha~ a specific surface area of from about 5.0 to about 6.50, preferably fro~ about 5.0S to about 6.2, and mo~t preferably from about 5.07 to about 6.11 m2/g. The potasBium alumino~ilicate ~2l~
- 10 - PAT~NTS
filler ha3 an average particle diameter of from about 1.0 to about 20.0, pref~rably from about 1.0 to about 10, and most pr~ferably from about 1.0 to about 5.0 micrometers. The average particle thickne~s of the filler i8 from about 0.5 to about 1.0, preferably from about 0.5 to about 0.8, and most preferably from about 0.45 to about 0.55, micrometers.
The ~urface area of th~ potassium aluminosilicate filler i8 important to the present invention because a ~urface area which i5 too large will le~d to an increase in the durometer of the f inal cured product, an increase in modulus, and a decrease in elonga ion.
On the other hand, a surface area which i8 too ~mall will lead to a decrease in the durometer of tha final cured product, a decrease in modulu~, an increa~e in ~longation and a decrea~e in tear properties.
The average particle ~iz~ in the pota88ium aluminosilicate filler i~ also important ~ecau~e if the average paxticle size i~ too large, the penmeability and swell properti~s of the final cured product increa~e and it becomes more dif~icult to control the shrinkage of the cured product. If the particle ~ize i8 too ~mall, the modulu~ o~ the cured product increa~-es, which makes the cur~ble composition harder to work with snd causes it to crumble e~8ily.
In addition, ~he amount of pota~sium aluminosili-c~te i8 important becau~e if an insufflcient ~mount i~
used, there will be no significant impro~ement in resistance to hydrocarbon oil8 or reduction in the shrinkage of the final cur~d product.
The most pre~erred potas~ium alumino~ilicate filler for US8 herein is pota~ium mica (al80 known as muscovite), having th~ formula RAl2(~1si30lo~(oH)2~ which .. ;,. ...
:,' . :' ', .
~. :. , 4 ~ ~
PATE~TS
~QE~L9~
A pota~sium aluminosllicate filler i~ added to a blend compri~ing at least one organopoly~iloxane gum, an optional MQ or ~ D-vinyl Q re~in or blends thereof, a silica filler, ~n optional vinyl~on-chain siloxane gum, and an organohydrogen~ilo~ane cro~s-linking agent.
The mixture produce~ a ~ilicone elastomer which is heat curable in the presence of a catalyst.
In one group of composition~, blends are formulated which comprise 100 part~ by weight of a polymer 8y8t~m. The polymer sy~tem compri~ at lea~t one dior~anopoly~iloxane having a visco~ity of about 3,000,0Q0 to about 100,000,000 centipoise ~ Cp8 ) at 25C, herein described a~ Components (A)-(D~, and up to 30 parts by weight, based on 100 part~ by weight of the at least one diorganopolysiloxane gum, of an MQ or M D-vinyl Q resin copolymer or resin copolymer blend, Component (F).
The organopolysiloxane gum Co~ponent~ (A)-(D) may be used in various combinations or ~eparately. The gu~
or gum~ should each have a viscosity o~ up to about 100~000,000 Cp8 at 25C. More preferab}y, gum components are u~ed which have visco~ities of from about 3,000,000 to about 100,000,000 Cp8 at 25C.
The gum vr gums may be (A) free o~ vinyl groups, (B) vinyl-stopped, (C~ have vinyl-on-chain, or (D) have both vinyl end stops and vinyl-on-chain. For purpo3es of cl~rificatio~, Component~ (A)~(D) will be explainad in qreater detail below. The polymsr sy~tems of the compo~itions of the pre~ent invention are defined a~
100 parts by weight. Any of the polymers t~)-(D) may make up the 0ntire weight of the polymer sy~tem, a portion of the entire weightl or may be completely :, ~, ', 2~2~'18 , ~, _ 5 _ PATENTS
60$I-1524 absent from the polymer ~ystem. The polymer sy~tem al80 include~ the re~in, Component ~F~, if used.
Up to 100 p~r~s by weight of the polymer system may be Component (A), ~n organopolysiloxane substantially free of vinyl and having a vi8c08ity of from abut 3,000,000 to about 100,000,000 cps at 25C.
Alternatively, Component (~) can comprise a mixture of such organopolysiloxanes.
Up to 100 parts by weiyht of the polymer system may be Component 5B), a vinyl chain-~topped organopolysiloxane, substantially free of vinyl-on-chain, having a viscosity of from about 3,000,000 to about 100,000,000 Cp8 ~t 25 C . Alternatively, Component ~B) can comprise a mixtura of such organopolysiloxanes.
Up to about 100 parts by weight of thP polymer 8y8tem may be Component (C), a vinyl-on-chain organopolysiloxane, free of ~inyl chain stops, having a vinyl content of about 5x10-3 to about 5 wei~ht percent and a vi8c08ity of from about 3,000,000 to about 100,000,000 Cp8 at 25C. Altern~ti~ely, Component (C) may comprise mixtures of ~uch organopolysiloxanes.
Up to about 100 parts by weight of the polymer sy~tem may be Component (D), a vinyl chaln-stopped, vinyl-on-chain organopolysiloxane having a vinyl content of about 5x10-3 to about 5 weight perc~nt.
Alternatively, Component (D) may compriRe mixture of ~uch organopolysiloxanes.
The resin copolymer ~F) may compri~e (1~ R3SiO1J2 monofunctional units (M units) and SiO2 ~u~dri-functional unit~ (Q units), where each R i8 independently selected from the group con~isting of ' ~ ' .
2~2~
` ~ --vinyl radicals and monovalent hydrocarbon radicals ree of aliphatic unsaturation. The ratio of M units to Q
unit~ ranges from about 0.5:1 to abou~ 1.5 5 1 ~ wherein about O.S to about 10.0 w~ight percent are vinyl groups.
Alternatively, the organopolysiloxane resin, Component (F), may comprise (2) an organopolysilo~ane re~in copolymer containing M and Q units as aforesaid and ~25iO2~2 difunctional (D units) where each R i~i indep~ndently selected from the group consi~ting of vinyl radical~ and monovalent hydrocarbon radicals free of aliphatic un~aturation. Each M unit may represent M or M' e.g. M-vinyl units, and each D unit may represent D or D~ e.g. D-vinyl unit~. The ratio of M
15 units to Q units i3 from 0 . 5 :1 to about 1. 5 :1 and the D unit~ are pre~ent in an amount of from about 1 to 70 mol percent based upon the total numbsr of mol~ of siloxy units in the copolymer. The xesinouR copolymer contains from about 0.5 to abou~ lO.0 weight percent vinyl groups. The organopolysiloxane resin copolymer may con~ain mixtureR of the MQ and the M D--vinyl Q, xesin~.
In addition to the exemplary polymer ~ystem made up of components ~A)- (F), and based upon 100 par~s by 25 weight of t:he polymer 5y8tem, the Compositions of ~he present invention also contain:
(G) from about 1 to about 50 par~ by weight, ba~ed upon the polymer system, of a pota~ium aluminosiilicate filler having a laminar strus::ture, a surfaee area of between about 5.0 and about 6.50 square m~ter3 per gram, an average particle diametor of from about 1 . 0 to about 20. 0 micrometers, and an average :, : . .. .:
. ~, .. .. .
~)92 r~
particle thicknes~ o~ from about 0.5 to about 1.0 micrometer~;
(H) up to about 200 parts based upon the polymer system of a finely divided silica filler;
(I) up to about 100 part~ based upon the polymer 8y8tem of a vinyl-stopped, ~inyl-on-ch~in polymer ha~ing from about 5x10-3 to about 5 weight percent vinyl; and (J) a random copolymer formed of a polydimethyl ~iloxane (P~MS) and a pol~methyl hydrogen siloxane (PMHS) having the forms R3SiO(SiORHSiOR2)XSiR~
wherein each R i8 independently chosen from a hydrogen or monovalent hydrocar~on xadical frea of aliphatic unsaturation containing 1 to about 8 carbon atoms, and x ranges from about 2 to about 100. In the present invention, th~ hydride i8 pr~ent in an amount ranging from about 0.1 to 10 part~ by weight ba~ed on the polymer ~ystem, preferably 0.5 to ~, and more preferably O~fl to 2.5 part3 by weight. When a hydride agent is employed, a platinum catAlyst may be ~ubstituted for the peroxide cataly~t to cure the compo~ition. In Component (J) x may vary ~o that (J) hax a viscosity ranging from about 5 to 500 cps, preferably from about 10 to about 100 cp~ and more preferabiy froM about 10 to 50 Cp8 at 25C.
In order to impro~e properties or processing, the compo~ition may al~o contain:
(R) up to about 2 part~ by weight of a t~tramethyl-divinyl ~ilazane ba~ed upon the polymer 8y8tem, and .~ ,,, . :
,, ~ .;
2a~2~l~s - 8 - PA~EN~S
(L) up to about 10 parts by weight ba~ed upon the polymer ~ystem of a processing aid ~ompriRing low vi~cosity silanol stopped siloxane fluid of from about 3 to about 500 centipoise at 25~C, or a dimethyl trimethoxy qiloxane polymer, or similar co~positions such a~ silanol or methoxy fluids of other visco~itie~.
Additionally, a cyclic methyl tetramer at about 15 to about ~0 percent by weigh~ based upon the weight of the filler (H~ may be used to treat the filler (H) prior to compounding.
A small amount of water may also be added to inCrQa~e the proceq~ibility of thQ blend. If usedr only up to about 0.1 parts by weight water based on the polymer system is u~ually employed.
lS In addition to the foregoing, a heat aging Component (M) such as fumed TiO2, iron octoate, Ce(OH)~
or mixtures thereof, may be present in rslatively small amounts, e.g., up to 2 parts by weight ba~ed upon the polymer 8y8tem. In the ex2mples below thç h~at aging component consists of 33 weight percent TiO2, 5 weight percent iron octoate solution ~which comprise~ about 12 weight psrcent iron in mineral 8pirit9 ), 10 wçiqht percent treated fumed silica (160 m2/g), and 50 wei~ht percent of an 800 penetratio~ vinyl-~topped, vinyl-on-chain gum.
An acid acceptor, Componenk (N), may al80 be addedto soak up acid. Thi~ acid could othexwi~e cau~e clea~aga of the product matrix. In one embodiment, ~N) compri~2s a masterbatch of about 25% MgO in a vinyl ~iloxane polymer.
~ he heat curable compositions of the pre~ent invention pro~ide heat cured silicone elastomer3 having good shrinkage 2nd uil resiqtance. ~hesç properties - ., . - ., ~ . , .. . . . ..
2 ~
~ 9 _ PA~ENTS
~Q~l~
are exhibited throughout extended p~riod3 of use at high temperatures making these compo8ition~ u9eful in automotiv~ gasketing applications.
DESCRIP~rION OF ?HE.INVENTION
Th2 composition~ of the pre~ent invention contain 100 parts by weight of a polymer system made up of:
a polydiorgano~iloxane gum having a visco~ity of about 3,000,000 to 100,000,000 Cp8 at 25C or blends of such gums, some or all of which may be vinyl-containing, described herein as Co~ponents (A)-(D);
and (F) an optional organopolysiloxane re~in of the ~Q or M D-vinyl Q types.
In addition to the exemplary polymer ~ys~em made up of Components (A)-(F), the co~positions of the present invention also contain:
(G) a pota~sium aluminosilicat~ fill~r having a laminar structure; ~H) a finely divided silica filler;
(I) an optional vinyl-on-chain ~iloxane gum; and (J) an organohydrogen~iloxane cros~-linking agent.
~0 Combinations o~ variou~ other component~ a~ described herein may also be added.
Component (G) is a potassium ~lumino~ilicate filler haviny a laminar structure. The filler i8 mixed with a siloxane composition in amounts from about 1 to about 50 parts by weight based on total weight of Component~ (A)-[L) described herein. Preferably, the filler i8 added in an amount between about 10 and about 40 parts by weight, more preferably from about 15 to about 30. The filler ha~ a specific surface area of from about 5.0 to about 6.50, preferably fro~ about 5.0S to about 6.2, and mo~t preferably from about 5.07 to about 6.11 m2/g. The potasBium alumino~ilicate ~2l~
- 10 - PAT~NTS
filler ha3 an average particle diameter of from about 1.0 to about 20.0, pref~rably from about 1.0 to about 10, and most pr~ferably from about 1.0 to about 5.0 micrometers. The average particle thickne~s of the filler i8 from about 0.5 to about 1.0, preferably from about 0.5 to about 0.8, and most preferably from about 0.45 to about 0.55, micrometers.
The ~urface area of th~ potassium aluminosilicate filler i8 important to the present invention because a ~urface area which i5 too large will le~d to an increase in the durometer of the f inal cured product, an increase in modulus, and a decrease in elonga ion.
On the other hand, a surface area which i8 too ~mall will lead to a decrease in the durometer of tha final cured product, a decrease in modulu~, an increa~e in ~longation and a decrea~e in tear properties.
The average particle ~iz~ in the pota88ium aluminosilicate filler i~ also important ~ecau~e if the average paxticle size i~ too large, the penmeability and swell properti~s of the final cured product increa~e and it becomes more dif~icult to control the shrinkage of the cured product. If the particle ~ize i8 too ~mall, the modulu~ o~ the cured product increa~-es, which makes the cur~ble composition harder to work with snd causes it to crumble e~8ily.
In addition, ~he amount of pota~sium aluminosili-c~te i8 important becau~e if an insufflcient ~mount i~
used, there will be no significant impro~ement in resistance to hydrocarbon oil8 or reduction in the shrinkage of the final cur~d product.
The most pre~erred potas~ium alumino~ilicate filler for US8 herein is pota~ium mica (al80 known as muscovite), having th~ formula RAl2(~1si30lo~(oH)2~ which .. ;,. ...
:,' . :' ', .
~. :. , 4 ~ ~
PATE~TS
6~ lS24 i~ a natural hydrous potas~ium aluminum silicate of the mica group. Another acceptable pota~sium aluminosili-cate filler (G) ha3 the formula RAl2(AlSi30lo)(F)2. Mica of the formula RHZAl2(SiO4)3 i8 al~o expected to impro~e S Rhrinkage and oil r~sistance if used according to th2 present inventlon.
The pot~sium aluminosilicate fillers used in the compo~itions of thi~ invention have a highly laminar flake structure. The micronized muscovite micas are preferred over the w~t ground mu~covite~ due to the former' 8 ~maller average particle 8iZ~. The laminar structure of the mica helps to CreatQ a uniform layered structure to minimize por~ in the cured matrix. This leads to lower compre~ion set, reduced permeation of gase~ and liqui~, and a lower degree of shrinkage of the cured final product.
Potassium aluminosilicate compounds are known in the art and can be obtained commercially.
The polymer ~ystem comprises a diorganosiloxane gum or blend of ~uch gwm8, ~ach o~ whi~h has a visco~ity from about 3,000,000 to about 100,000,000 cp~
at 25C. Prefarably, the gums each have a visco~ity o~
between abou~ 7,000,000 and 84,000,000 cps, mora pre~erably, about 13,000,000 cp~ at 25C. On~
exemplary gum i~ a vinyl stopped gum havlng subst~ntlally no vinyl~on-chain, described above a~
Co~ponent ~B). Tha organo groups in the gum should all be monovalent hydrocarbon radicals. Gum~ may al~o be used which have a weight percent vinyl concentration of from about 5x10-3 to abou~ 1. More preferable gum5 have a weight percent vinyl concentration in the range from about 6.5x10 3 to about 0.03, more pre~erably from about 8x10-3 to ~bout l. SX10-2 and more preferably yat ~: : : ::
:
--`"` 2V92~
from about 8x10-3 to about 10 2x10-2. The organo groups in the vinyl polymer or polymer3 of ~uch gum~l ~hould all ~e monovalent hydrocarbon radicals.
In a preferred embodiment, at least one gum of the polymer system i8 Componen~ (B), and preferably ha~ the ~tructure:
YiSiORl2 (SiOR~2)x(SiOR22)y SiRl2Vi;
wherein Yi i8 vinyl and each Rl is independently chosen from monovalent hydrocarbon free radical~ free of aliphatic unsaturation and containing 1 to about 8 carbon atom~; each R~ i8 independently cho~en from monovalent hydrocarbon radicals containing 1 to about 8 carbon atom3; and x and y are integers chosen such that the viscosity is about 3,000,000 to about 5 100, 000, 000 CpE at 25. In other preferred embodiments~ x and y are integers cho~en such that Component (B) has a vi~co~ity which ranges from about 3,000,000 to about 85,000,000 Cp9 at 25C and a weight percent vinyl concentration in the r~nge ~rom about 5xlO-3 ~0 about 2x10-2, preferably from about 8xlO-~ to about 1.5x10-2 and more preferably ~rom about B.OxlO-' to about l.~x10-2.
Llke visco~ity, penatration i9 another way of clas~ifying elastomeric materials. Penetration i8 measured using Universal Penetrometer by Preci~ion Scienti~ic ~odel No. 73510 with a substantially air free sample. The sa~ple pene~ration i~ mea~ured at 25-C~1C using a 100 g weight and a 1/4i~ diameter by 3/1$" needle foot with rounded edges. The ne*dle i~
lowered until it ju~t ~ouche~ the surface of the polymer. 'rhen, the time to achieve up to 300 mm " .: "
2~2~
, 6~S~
pen~tration i8 determined or the amount of penetration after 60 ~ec. Penetration gum is defined as: :
De~th of Penetration X 60 ~ec. at Z5C
Time Penetration may be controlle~ by controlling the molecular weight and the visco~ity of the gum.
In accordance with the invention, the amount of polymer pre~ent in the final product may vary.
However, for purpo~es of explanation herein, it i~
a~Rum~d that 100 parts by weight of polymer is combined with varying amount3 o f the other components, and the amount of pol~mer in the final pxoduct may thereby be inferred.
In the E~ample~ below, the components for the polymer system include Component ~Bl), a Yinyl-stopped gum of apprvximately 9000 D unit~ in length having a penetration of about 300, and ~ubst2ntially no ~inyl-on-chain. Component (C1) i~ a vinyl-on-chain, methyl-stopped gum of approximately g000 D units in length having a penetration of about 300 and a vinyl content of about 0.2 weight per~ent. Other vinyl-on-chain gum9 inolude tho~e which havo a vinyl content o~ between ab~ut 0.05 and about 4 wei~ht percent vinyl. Componen~
(B2) is a vinyl-stoppQd gum of approximately 7000 D ~:
units in length having a penetration of about 800, and sub~tantially no vinyl~on-chain. Component (Al~ is a methyl chain stopped gum of approximately 9000 D units in length ha~ing a penetration of about 800 and ~ubstantially no ~inyl-on-chain. Component (C2) is a methyl chain-stopped gum of approximately 8750 D units in length having a penetration of about 400 ~nd about 0.6 weight percent ~inyl.
. .
~ ~ 9 ~ 8 60SI~15Z4 Component (F) may be (1~ an organopolysiloxane resin copolymer in an appropriate solvent ~e.g.
xylene~. The re~in copolymer may contain R~SiOI~2 monofunctional units tM unit~) and SiO2 quadri-functional units (Q uni~s3, where e~ch R i~independently ~elec~ed from the group con~i~ting of vinyl radicals and monovalent hydrocarbon radicals free of aliphatic un~aturation. The ratio of M units to Q
unit~ range~ from about 0.5:1 to about 1.5:1, whexein about 0.5 to lD.0 weight percent are vinyl groups.
Alternatively, Component (F) may compri~e (2) an organopolysiloxane resin copolymer containing M and Q
units a8 aforesaid and R2SiO2~2 difunctio~al (D or D-vinyl units~, in an appropriate solvent, wh~re each R
i~ independently selected from the group consisting of vinyl radical~ and monovalent hydrocarbon radical~ free of aliphatic unsaturation. The ratio of M units to Q
units i~ from 0.5:1 to about 1.5:1 and the D or D~Yi units are present in an amount of from about 1 to 70 mol percent based upon the total number of mols o~
siloxy units in th~ copolymer. The resinous copolymer contains from about 0.5 to about 10.0 weight percent vinyl groups. The organopolysiloxane resin copolymer o~ Component (F) m~y contain mixtures o~ the MQ and the M D-vinyl Q, res in8 .
The organopoly~iloxane re~in copo~ymers of Component (F~ in the pre~ent composition and their manufacture axe well known in the art. Such resins are usually produoed by hydrolysi~ of chloro~ilane~ in a 3D proces~ described in U.S. Patent No. 3,~36,366 which is incorporated herein by reference.
Component tF) may be presen~ in he compo~ition of the pre~ent invention in an amount of up to about 3D, , . , ~, .
- 15 - PA~EN~5 preferably from l.O to 20 and more preferably from 4 to about 12 parts by weight based on the total weight of Components (A)-(D). Component (F) in the Examples below compri~es (F2) dispersed in xylene. Much of the S xylene has been vacuum stripped 50 a~ ~o result in a composition comprising 60% by weight 801ids and 40% by weight xylene.
Examples I and III below are composition~ which contain a poiymer system having Components (~1), tCl) and lF)~ including the xylene component, in amounts which total lO0 part~ by weight. The resin component makes up 6.3 percent by weight of the polymer system.
The proce~s for manufacturing the compositions of Example0 I ~nd III include~ a cook and strip step to facilitate the removal of the residual ~ylene from the ~inished compound.
Example~ II and IV below are compositio~ which contain a polymer system having Component~ (Al), (B2~
and ~C2) in amount~ which total lO0 part~ by weight.
No resin component is used in Examples II and IV.
Component (H) compris~ from about 5 to about 200, pxefarably from about 10 to about lO0 and more prefera~ly from about 20 to about 50 part~ by weight of reinforcing ~illers ~uch as SiO2 based on thR polymer sy~tem, Components (A)-(F). Examples of reinforcing fillers that may be u~ed include fumed silica and precipitated silica, with fum~d silica being preferred.
The filler (H~ may be pretrea~ed or ~reated in-situ with various agents, for example cyclopoly3iloxane~ as disclosed in U.S. Patent No. 2,938,009 to Lucas and silazane~ a~ di~closed in U.S. Patent No. 3,635,743 to Smith. The cyclopoly-~iloxane~ may be, for esample, a , . , , , - , . . . . .
, - , ,, . , - :
- 16 - PATEN~S
cyclotetramethyl siloxane present in the amount of about 15 to 20 weight percent of the fillQr (H).
Preferred fumed silica filler~ may have a ~urface ar~a of about 100 m2/g to about 300 m2/g and preferably about 160 m2/g to abou~ 240 m2/g. ~he high~x ~urface area fillers tend to result in better propertie~, however, they are more expensive than the lower surface ares fillers and require surface treatments or more proce~sing aid to incorporate them into the gum. In the Examples below, the filler, Component (H), comprises a fumed silira filler having a surface area cf about 160 m2/g which has been pretreated with octamethyl cyclotetrasiloxane.
A high vinyl-on~chain siloxane gum (I) may be added in an amount of up to about 100 parts by weight based on the polymer system, but may not be dQ~ired if, for example, much Component ~D) is usedO While Component (I) is 8imilar, if not identical, to Component (D), it may be added in addition to the entire composition and thus not be con~ide~ed in calculating the polymer system, Compon~nts (A)-(D).
The actual amount o~ Component (X) to be added varies depsnding upon the vinyl con~ent in Component (I), the amount o~ Component ~D) and the amount of cro~s-linkiny de~ired. The amount of cro~s-linking ca~ clo6ely control the propertie~ exhibited ~y the cured pxoduct.
~ he vinyl polymer or polymers of Component (I) contain vinyl-on-chain group~ and/or vinyl end-group~.
In preferred embodiments, Component (I) ha~ the formula:
ViSiORl2 (SiORl~RVl)X(SiOR22)y SiRIzVi , ' - 17 - PA~ENTS
60SI-152~
Nherein Vi is vinyl, RVl is a vinyl radical having from 2 to about 10 carbon atom~, each R1 i~
independ2ntly cho~en from a vinyl radioal having from 2 to about 10 carbon atoms, and a monoval nt hydrocarbon radical, ree of aliphatic un~aturation and containing 1 to abou~ ~ carbon atoms, each R2 iS
independently chosen from a vinyl radical having from 2 to about 10 carbon atoms, and a monovalent hydrocarbon radical, free of aliphatic unsa~uration and containing 1 to about 8 carbon atoms, and x and y are integers, wherein x, y, RVl, Rl and R2 are chosen ~uch tha~ Componen~ (I) has a weight percent vinyl concentration in the range from about sx10-3 to about 5 weight percent, preferably from about 0.01 to about 4, and more preferably from about 0.05 tv about 4. The amount of Component (~3 added ~o the blend may be increased when ~he vinyl concentration of Co~ponent (I) is low, and a lesser amount of Component ~I) may be added when its vinyl concentra~ion i~ high. For example, when using a vinyl-on-chain yum having a vinyl content of abo~t 4 welght percent, only about 0.5 part by weight based on the polymer qy~tem i.8 added. When u~in~ a gum having a vinyl content of about Q.2 to about 0.6 weight porcent, abou~ 5 par~s by weight oan be added ba~ed on the polymer sy~tem.
The vinyl-on-chain units of Component (I) provide increased cro~-linking of the cured rubb2r and enhance those propcrties necessary for use in gasketing, ~ealing and vibration dampening applications.
~hQ vinyl containing polymers of Component ~I) can be made by a proce~s well known in the art~ for example, by reacting cyclo~etrasiloxane~ in the presenc0 of low molecular weight, linear vinyl chain -' ',,,, ~ ., ' ' :
~ ~ 3 ~
- 18 - PAq!E,'NTS
60~-~5?.4 ~toppers at high temperatures in the pre~ence vf b~sic catalys~ so as to yield a polymer of the desired molecular weight. When the reaction i8 over, the catalyst i~ neutralized and the exc~3s cyclics are vented off to re~ult in the desired polymer. By contrslling the amount of chain stopper and the temperature of the reaction, the molecular weight of the desired vinyl-containing polymer end product can be controlled. For more detail~ of the proce~s by which ~uch vinyl con~aining polymer~ are produced, reierence iR made, for example, to U.S. Patent No. 3,660,345, which i~ incorporated herein by reference. Component ~ preferably a vinyl-on-chain diorganopolysiloxane or ~inyl-on-chain diorganosiloxsne blend.
In addition to the foregoing, Component (J) in the form of a hydride cros~-linking agent may be employed.
In a preferred embodiment, Component (J) may be a random copolymer formed of a polydimethyl silo~ane (PD~S) and a polymethyl hydrogen siloxane (PMHS) having the form:
R3SiO(SiORHSiORz)xS iR3 whereln each R i8 independently cho~en from a hydrogen or monovalent hydro~arbon radical free of aliphatic un~aturation containing 1 to about 8 carbon atoms, and x rangeq from about 2 to about 100. ~n the present inv~ntion, Component (J) i8 pre~ent in an amount ranging from about 0.1 to 10 parts by weight based on the pol~mer system, preferably 0.5 to 8, and more preferably 0.8 ~o 2.5 parts by weight. When a hydride agent i5 employed, a platinum cataly~t may be substituted for the peroxide catalyst to cure ths ".
.
. ~ :
6~
- 19 ~ PATENT~
60SI-1$?4 composition. In Component (J) x may vary BO that (J~
ha~ a viscosity ranginy from about 5 to S00 cps, prefer2bly from about 10 to about 100 Cp8 and more preferably from about 10 to 50 CpB at 25C.
S The linear hydride described above can be made by m~ny proced~res which are known in the art and particularly by ~he hydroly~is of appropriate chlorosilane~. See for example, U.S. Patent No.
4,041,101 which is incorporated herein by reference.
In the Example~ below, Component (J) ha~ a viscosity of about 30 centiqtokes, a hydride content of about 0.8 percent by weight, ~nd a chain length of about 100 units.
Component (R) i8 a vinyl terminate~ silazane lS coupling agent and ~urface treatmen~ for the filler which may take the form:
ViSiR2NHSiR2Vi wherein R i~ an organic such a~ CH3. 'rho coupling agent promote~ bonding b~tween gum component~ (A)-(D) of the polymer system ~nd (H) and between the resin components (F) and (H), and m~y be applied to the reinforcing filler, Component (~l), prior to mixing with the other components.
Component (K) may be vinyl stopped linear silazane such a~ tetramethyl-divinyl silazane. The material is added for enhancing the bonding of filler to poly~er.
In the pre~ent in~ention, the silazane also acts as a filler treatment in-situ.
Component (K) is preferably pre~ent in an amount of up to about 2 parts by weight, more preferably up to about a . 3 parts by weight based on the weight of the ~- ~ V 9 ~
- 20 - PAT~N'rS
polymer sy~tem. Component (K) may be pre~ent in an amount o only about 0.03 parts by weight based on 100 parts of the polymer system, how~er, ~l~ghtly higher amount~ are pxeferred.
In addition to, in con~unction with, or in place of Component (K), small amounts of hex~nethyl disilazane may be u~ed to treat fumed silica filler prior to mixing the filler with the other components, or in-~itu. If used, up to about 20 part~ by weight of hexamethyl disilazane i5 added ba~ed on 100 parts of Component (H).
Other componentR may al80 be employed as discussed hereinafter. For example, in order to allow for ea~iex incorporation of the filler in the polymer ~ystem, Component (L), a proce~sing aid or pla~ticizer is employed. In the preferred embodiment, Component (L) i~ a low viscosity silanol or me~hoxy stopped siloxane fluid having a viscosity ranging from about 3-500 cp~
and preferably 3 to 50 Cp8 at 25C. The silox~ne fluid i~ an equilibrium mix of low molecular weight oli~omers of about 4 to about 10 D U~itB ~ pre~erably between 4 and S repea~ing units in length with a minimum amount of cyclic8 in equilibrium with the oligomer~. The proces~ing aid (L) may have the ~orm of ~R2SiOI~2~XOH or (R2SiOI~2)XORl where each R i~ CH~, each Rl is an alkyl, and x i8 between 4 and 10, preferably between 4 and 6, with rs~ulting cyclics of the same number of units in *quilibriumO Di and tri alkoxy terminated siloxanes such a~ trimethoxy siloxane may al~o be used as proce~s aids.
Component (L) may have th~ formula-R30~R2Sio~XR3 ..
.
2~9~ll8 wherein each R is CH3, and x i5 bet~een 4 and 10 and preferably between 4 and 6, with resulting cyclics in the same number of Uni~3 in equilibrium; and ~3 i8 selected from the group consi~ting of alkyl radicals having 1 to about 8 carbon atom~ and hydrogen, with hydrogen being preferred.
In the present invention, the processing aid is pre~ent in amounts between 2 and 10 parts by weight based on the polymer sy~tem, preferably between 2.5 and 5.0 part~ by weight and most preferably about 3.5 part~ by weight based on the polymer 6ystem. It should be understood tha~ typically the more filler tha~ i8 used the greater amount of processing aid i~ employed.
In the Ex~mple~ below, Component (L) has a silanol content of about 7.5 % by weight although a ~ilanol content of about 5 to about 10 weight percent is expected to provide good results.
A ~m~ll amount of water may al80 be added to increase the proce~sibility of the blend. If used, only up to about 0.1 part~ by weight water based on the polymer system i~ uYually employed.
To improve the heat-age resi~tanco o.E the cured composition~ of the presen~ invention, Component (M), a heat~age additive, may be employed. The heat aging component such as fumed TiO2, iron octoate, Ce(OH)4, or mixtuxe~ thereof r may be present in relatively small amount~, e.g., up to 2 parts by weight ba~ed upon the polymer ~ystem. In the example~ below the heat aging Compone~t (~ consist~ of 33 weight percent TiO2, 5 weight percent iron octoate l12% iron in mineral ~pirits), 10 weight percent trea~.ed fumed ~ilica (160 mZ/g), and 50 weight percent of an 800 penetration vinyl-stopped, vinyl-on-chain gum.
-/ . ~
2 ~ 8 60~I-l524 Only up to about two parts by weight Component (M~
i8 needed based on the polymer system to improve the heat-age characteristics of the composition. In the Example~ below, 0.9 and 1.3 part~ by weight of Component (M) are u~ed based on the total weight of the other componen~s.
An acid acceptor, such as MgO or ZnO, Component (N~, may also be added in amounts from 0.5 to about 10 parts by weigh~ ba~ed on th~ polymer ~ys~em. This acid could otherwi~e cause cleavage of the product matrix.
In the Examples below, 1.0 parts by weight of MgO
masterbatch which comprises about 25% MgO in a methyl vinyl poly-siloxane is used for Component (N) based on the polymer system.
Other components which may be added to the blends of the present invention include, but are not limited to:
(O) a heat-age additive comprising cerium hydroxide, preferably about 75% by weight, ~0 mastQrbatched in polydimethylsiloxane fluid havln~ a viscosity of about 30,000 cp~ at 25C.
(P) which is a coloring agent comprising 57~
carbon black di~persed in v~nyl-polydimethyl siloxane ~luid available as K8124 ~rom Kenrich Petrochemical~, 25 Bayonne, New Jersey; and ~ Q) which is zinc oxide ~ZnO) added as an ~mphoteric scavenger for Lmproving resi~tance to lubricating oils.
I~ order to form a heat curable rubber, an organic peroxide, free radical initiator or curing cataly~t is provided. The preferred peroxide curing agents are thermal decomposition organic peroxides conveniently used to cure silicone elastomers. Examples of suitable : ' : ~ ~ :
~9~
- 23 - PAT$~TS
organi~ peroxide free radical initiators for use in the present invention are disclosedr for example, in U.S.
Patent No. 4,S39,357 to Bobear which i8 incorporated herein by reference. Suitable peroxide catalysts include dialkyl peroxide such a~ di-tertiary-butyl peroxide, tertiaxy-butyl-triethylmethyl peroxide, di-tertiary-butyl-tertiary-triphenyl peroxide, t-butyl perbenzoate and a di-tertiary alkyl peroxide such as dicumyl peroxide. Under certain condition~ hereinafter de~cribed, such as when a hydride is used, a platinum catalyst may be employed instead as an initiator. In the examples below, the preferred catalyst is a vinyl specific catalyst such a~ 2,S dimethyl-2,5-di~t-butyl peroxy~ hexane i.e., Lupersol ~101 available from Lu~idol, Corp., Buffalo, New York, herein referred to as Component (R).
In the Example~ below, Componen~ (S~ is the cataly3 Lupersol~ 101 in a masterbatch comprising 33%
Lupersol~ 101, 33~ calcium carbonate and 33~ dLmethyl~
siloxane oil having a ~i3c08ity of 30,000 c~nti~tokes.
Freqllently used thermal decomposition catalysts activate within a temperature range of about 330F to about 390F.
~S
The following Examples shown below used components mixed in various proportions to produce heat curable silicone rubber compositions.
EXAM~PLE5 I -~IV
The Components tA)-(S) were mixed in various proportions to produce the compositions of Examples I-IV listed below in Table I. In each Example, : . . .
4 l~ ~
- 2 4 ~ PATENTS
Components (A) - ( L) were mixed prior to adding the remaining components. The component~ are expressed in part~ by weight.
Example Component I II III IV
( Bl ~ 85 -- 85 (Cl) 5 - 5 (B2) _ 65 _ 65 10 (A~) ~ 20 - 20 (C2) - 15 - 15 (F) 10 - 10 ~ G) 29 . 0 29 .1 - -(H) 30 36 30 36 15 (J) 1.4 1.2 1.4 1.2 (K) 0.12 0.06 0.12 0.06 (L) 3 3 3 3 : :
(~q) o.g 1.3 0.9 1.3 (N) 1.4 2.6 1.4 2.6 2Q (O) 0~ 9 0 . 9 - ~.
(P) 0.4 0.7~ 0.4 0.72 (Q) 5.6 - 5.6 -( R) - 0 . 57 - 0 . 57 (S) 1.5 - 1.5 ~ L 8 s~
- ;2 5 - PA'rBN~S
1~ 2 4 Table II bxlc:w shs~w~ th~ prop~rt~s of the composition~ o~ }~X~lmple8 I-IV after adding all components arld curinçT. All cure cond~ tions were with a peroxide ::atalyst. The compe~itionE~ of th~ Example3 5 were molded at 350~F for 15 minutes.
ExamE~e Pre~erty I I I ~a. IV
Shore A 59 54 49 4S
10 Tensile, p~i 1210 10471367 14~4 E:longation, % 709 748 767 849 ~-Tear-~, ppi 120 202 257 Z23 8p- gr~lrity 1.291 1.252 1~1701.170 Comp. Set, ~ le.d. 38.717~1 33.6 15 T0~t data were obtained f .rom thQ f ollowlng A5~l methods and procedures: Shore A - D-2240; Ten~ile, Elong2tion and Modulus - D-4 12 ~ D~e C ); Te4r - D-624 (Dio 1~); and Compression Set - D-395 ~Method B 22 hrs ~ 350F) T~ble II~ shows khe change in propertie~3 of the -~
20 compo~ition~ of Ex~mple3 I-IV after a 70 hour oil immer~ion at 300 np in a 5W-30 m~tor c;il per ~5~ D-471 .
:: .
; .
2~2~8 - 26 - PA~ENTS
TABLE III
Example Property I II III IV
Shore A -17 -21 -l9 -20 Tensile -27.3 -30.2 -51.1 -56.5 ~ change Elongation -lO.0 -18.1 -34.9 -41.0 % change Weight 20.5 22.7 25.4 29.3 ~ change Volume 30.3 32~0 34.9 38.6 % change Table IV below shows the ch~nge in properties of the compo~itions of Example I-IV after immersion in ASTX
reference oil #3 for 70 hours at 300F per AST~ test method D-471.
T~ LE IY
Example ,, ,~
Property I II ~I IV
20 Shore A -19 -23 -19 -14 Tensile -35.4 -36.1 -63.S -72.7 ~ chang~
Elongation -23.1 -26.1 -53.5 -33.0 % chang~
25 Weight 27.6 2g.8 36.7 39~8 % change Volume 39.2 42.5 47.4 49.0 % change .: .... ,: -, , :
:: :. . : ~ ~-, ' 2~2~8 .
- 27 - PA~ENTS
The compositions of Examplas I and II exhibit enhanced properties which make them useful for many automoti~e gasketing applications. As can be seen in Table III, 10i3ses in tensile strength and elongation are significantly impro~ed and volume swell and weight changes are siynificantly decreased in the compositionis containing the pota88ium al~minosilicate filler after oil immersion testing of the compositions. The observed trend is an improvement in shrinkage resistance and heat age and oil immersion resistance by the inclusion of Component (G).
Although the present invention has been described in connection with preferred embodLmentis, it will be appre-ciated by those skilled in the art that additions, modi-fîcations, substitutions and deletions no~ specificallydescribed may be made without departing from the spirit and scope of thie invention defined in the appended claims.
The pot~sium aluminosilicate fillers used in the compo~itions of thi~ invention have a highly laminar flake structure. The micronized muscovite micas are preferred over the w~t ground mu~covite~ due to the former' 8 ~maller average particle 8iZ~. The laminar structure of the mica helps to CreatQ a uniform layered structure to minimize por~ in the cured matrix. This leads to lower compre~ion set, reduced permeation of gase~ and liqui~, and a lower degree of shrinkage of the cured final product.
Potassium aluminosilicate compounds are known in the art and can be obtained commercially.
The polymer ~ystem comprises a diorganosiloxane gum or blend of ~uch gwm8, ~ach o~ whi~h has a visco~ity from about 3,000,000 to about 100,000,000 cp~
at 25C. Prefarably, the gums each have a visco~ity o~
between abou~ 7,000,000 and 84,000,000 cps, mora pre~erably, about 13,000,000 cp~ at 25C. On~
exemplary gum i~ a vinyl stopped gum havlng subst~ntlally no vinyl~on-chain, described above a~
Co~ponent ~B). Tha organo groups in the gum should all be monovalent hydrocarbon radicals. Gum~ may al~o be used which have a weight percent vinyl concentration of from about 5x10-3 to abou~ 1. More preferable gum5 have a weight percent vinyl concentration in the range from about 6.5x10 3 to about 0.03, more pre~erably from about 8x10-3 to ~bout l. SX10-2 and more preferably yat ~: : : ::
:
--`"` 2V92~
from about 8x10-3 to about 10 2x10-2. The organo groups in the vinyl polymer or polymer3 of ~uch gum~l ~hould all ~e monovalent hydrocarbon radicals.
In a preferred embodiment, at least one gum of the polymer system i8 Componen~ (B), and preferably ha~ the ~tructure:
YiSiORl2 (SiOR~2)x(SiOR22)y SiRl2Vi;
wherein Yi i8 vinyl and each Rl is independently chosen from monovalent hydrocarbon free radical~ free of aliphatic unsaturation and containing 1 to about 8 carbon atom~; each R~ i8 independently cho~en from monovalent hydrocarbon radicals containing 1 to about 8 carbon atom3; and x and y are integers chosen such that the viscosity is about 3,000,000 to about 5 100, 000, 000 CpE at 25. In other preferred embodiments~ x and y are integers cho~en such that Component (B) has a vi~co~ity which ranges from about 3,000,000 to about 85,000,000 Cp9 at 25C and a weight percent vinyl concentration in the r~nge ~rom about 5xlO-3 ~0 about 2x10-2, preferably from about 8xlO-~ to about 1.5x10-2 and more preferably ~rom about B.OxlO-' to about l.~x10-2.
Llke visco~ity, penatration i9 another way of clas~ifying elastomeric materials. Penetration i8 measured using Universal Penetrometer by Preci~ion Scienti~ic ~odel No. 73510 with a substantially air free sample. The sa~ple pene~ration i~ mea~ured at 25-C~1C using a 100 g weight and a 1/4i~ diameter by 3/1$" needle foot with rounded edges. The ne*dle i~
lowered until it ju~t ~ouche~ the surface of the polymer. 'rhen, the time to achieve up to 300 mm " .: "
2~2~
, 6~S~
pen~tration i8 determined or the amount of penetration after 60 ~ec. Penetration gum is defined as: :
De~th of Penetration X 60 ~ec. at Z5C
Time Penetration may be controlle~ by controlling the molecular weight and the visco~ity of the gum.
In accordance with the invention, the amount of polymer pre~ent in the final product may vary.
However, for purpo~es of explanation herein, it i~
a~Rum~d that 100 parts by weight of polymer is combined with varying amount3 o f the other components, and the amount of pol~mer in the final pxoduct may thereby be inferred.
In the E~ample~ below, the components for the polymer system include Component ~Bl), a Yinyl-stopped gum of apprvximately 9000 D unit~ in length having a penetration of about 300, and ~ubst2ntially no ~inyl-on-chain. Component (C1) i~ a vinyl-on-chain, methyl-stopped gum of approximately g000 D units in length having a penetration of about 300 and a vinyl content of about 0.2 weight per~ent. Other vinyl-on-chain gum9 inolude tho~e which havo a vinyl content o~ between ab~ut 0.05 and about 4 wei~ht percent vinyl. Componen~
(B2) is a vinyl-stoppQd gum of approximately 7000 D ~:
units in length having a penetration of about 800, and sub~tantially no vinyl~on-chain. Component (Al~ is a methyl chain stopped gum of approximately 9000 D units in length ha~ing a penetration of about 800 and ~ubstantially no ~inyl-on-chain. Component (C2) is a methyl chain-stopped gum of approximately 8750 D units in length having a penetration of about 400 ~nd about 0.6 weight percent ~inyl.
. .
~ ~ 9 ~ 8 60SI~15Z4 Component (F) may be (1~ an organopolysiloxane resin copolymer in an appropriate solvent ~e.g.
xylene~. The re~in copolymer may contain R~SiOI~2 monofunctional units tM unit~) and SiO2 quadri-functional units (Q uni~s3, where e~ch R i~independently ~elec~ed from the group con~i~ting of vinyl radicals and monovalent hydrocarbon radicals free of aliphatic un~aturation. The ratio of M units to Q
unit~ range~ from about 0.5:1 to about 1.5:1, whexein about 0.5 to lD.0 weight percent are vinyl groups.
Alternatively, Component (F) may compri~e (2) an organopolysiloxane resin copolymer containing M and Q
units a8 aforesaid and R2SiO2~2 difunctio~al (D or D-vinyl units~, in an appropriate solvent, wh~re each R
i~ independently selected from the group consisting of vinyl radical~ and monovalent hydrocarbon radical~ free of aliphatic unsaturation. The ratio of M units to Q
units i~ from 0.5:1 to about 1.5:1 and the D or D~Yi units are present in an amount of from about 1 to 70 mol percent based upon the total number of mols o~
siloxy units in th~ copolymer. The resinous copolymer contains from about 0.5 to about 10.0 weight percent vinyl groups. The organopolysiloxane resin copolymer o~ Component (F) m~y contain mixtures o~ the MQ and the M D-vinyl Q, res in8 .
The organopoly~iloxane re~in copo~ymers of Component (F~ in the pre~ent composition and their manufacture axe well known in the art. Such resins are usually produoed by hydrolysi~ of chloro~ilane~ in a 3D proces~ described in U.S. Patent No. 3,~36,366 which is incorporated herein by reference.
Component tF) may be presen~ in he compo~ition of the pre~ent invention in an amount of up to about 3D, , . , ~, .
- 15 - PA~EN~5 preferably from l.O to 20 and more preferably from 4 to about 12 parts by weight based on the total weight of Components (A)-(D). Component (F) in the Examples below compri~es (F2) dispersed in xylene. Much of the S xylene has been vacuum stripped 50 a~ ~o result in a composition comprising 60% by weight 801ids and 40% by weight xylene.
Examples I and III below are composition~ which contain a poiymer system having Components (~1), tCl) and lF)~ including the xylene component, in amounts which total lO0 part~ by weight. The resin component makes up 6.3 percent by weight of the polymer system.
The proce~s for manufacturing the compositions of Example0 I ~nd III include~ a cook and strip step to facilitate the removal of the residual ~ylene from the ~inished compound.
Example~ II and IV below are compositio~ which contain a polymer system having Component~ (Al), (B2~
and ~C2) in amount~ which total lO0 part~ by weight.
No resin component is used in Examples II and IV.
Component (H) compris~ from about 5 to about 200, pxefarably from about 10 to about lO0 and more prefera~ly from about 20 to about 50 part~ by weight of reinforcing ~illers ~uch as SiO2 based on thR polymer sy~tem, Components (A)-(F). Examples of reinforcing fillers that may be u~ed include fumed silica and precipitated silica, with fum~d silica being preferred.
The filler (H~ may be pretrea~ed or ~reated in-situ with various agents, for example cyclopoly3iloxane~ as disclosed in U.S. Patent No. 2,938,009 to Lucas and silazane~ a~ di~closed in U.S. Patent No. 3,635,743 to Smith. The cyclopoly-~iloxane~ may be, for esample, a , . , , , - , . . . . .
, - , ,, . , - :
- 16 - PATEN~S
cyclotetramethyl siloxane present in the amount of about 15 to 20 weight percent of the fillQr (H).
Preferred fumed silica filler~ may have a ~urface ar~a of about 100 m2/g to about 300 m2/g and preferably about 160 m2/g to abou~ 240 m2/g. ~he high~x ~urface area fillers tend to result in better propertie~, however, they are more expensive than the lower surface ares fillers and require surface treatments or more proce~sing aid to incorporate them into the gum. In the Examples below, the filler, Component (H), comprises a fumed silira filler having a surface area cf about 160 m2/g which has been pretreated with octamethyl cyclotetrasiloxane.
A high vinyl-on~chain siloxane gum (I) may be added in an amount of up to about 100 parts by weight based on the polymer system, but may not be dQ~ired if, for example, much Component ~D) is usedO While Component (I) is 8imilar, if not identical, to Component (D), it may be added in addition to the entire composition and thus not be con~ide~ed in calculating the polymer system, Compon~nts (A)-(D).
The actual amount o~ Component (X) to be added varies depsnding upon the vinyl con~ent in Component (I), the amount o~ Component ~D) and the amount of cro~s-linkiny de~ired. The amount of cro~s-linking ca~ clo6ely control the propertie~ exhibited ~y the cured pxoduct.
~ he vinyl polymer or polymers of Component (I) contain vinyl-on-chain group~ and/or vinyl end-group~.
In preferred embodiments, Component (I) ha~ the formula:
ViSiORl2 (SiORl~RVl)X(SiOR22)y SiRIzVi , ' - 17 - PA~ENTS
60SI-152~
Nherein Vi is vinyl, RVl is a vinyl radical having from 2 to about 10 carbon atom~, each R1 i~
independ2ntly cho~en from a vinyl radioal having from 2 to about 10 carbon atoms, and a monoval nt hydrocarbon radical, ree of aliphatic un~aturation and containing 1 to abou~ ~ carbon atoms, each R2 iS
independently chosen from a vinyl radical having from 2 to about 10 carbon atoms, and a monovalent hydrocarbon radical, free of aliphatic unsa~uration and containing 1 to about 8 carbon atoms, and x and y are integers, wherein x, y, RVl, Rl and R2 are chosen ~uch tha~ Componen~ (I) has a weight percent vinyl concentration in the range from about sx10-3 to about 5 weight percent, preferably from about 0.01 to about 4, and more preferably from about 0.05 tv about 4. The amount of Component (~3 added ~o the blend may be increased when ~he vinyl concentration of Co~ponent (I) is low, and a lesser amount of Component ~I) may be added when its vinyl concentra~ion i~ high. For example, when using a vinyl-on-chain yum having a vinyl content of abo~t 4 welght percent, only about 0.5 part by weight based on the polymer qy~tem i.8 added. When u~in~ a gum having a vinyl content of about Q.2 to about 0.6 weight porcent, abou~ 5 par~s by weight oan be added ba~ed on the polymer sy~tem.
The vinyl-on-chain units of Component (I) provide increased cro~-linking of the cured rubb2r and enhance those propcrties necessary for use in gasketing, ~ealing and vibration dampening applications.
~hQ vinyl containing polymers of Component ~I) can be made by a proce~s well known in the art~ for example, by reacting cyclo~etrasiloxane~ in the presenc0 of low molecular weight, linear vinyl chain -' ',,,, ~ ., ' ' :
~ ~ 3 ~
- 18 - PAq!E,'NTS
60~-~5?.4 ~toppers at high temperatures in the pre~ence vf b~sic catalys~ so as to yield a polymer of the desired molecular weight. When the reaction i8 over, the catalyst i~ neutralized and the exc~3s cyclics are vented off to re~ult in the desired polymer. By contrslling the amount of chain stopper and the temperature of the reaction, the molecular weight of the desired vinyl-containing polymer end product can be controlled. For more detail~ of the proce~s by which ~uch vinyl con~aining polymer~ are produced, reierence iR made, for example, to U.S. Patent No. 3,660,345, which i~ incorporated herein by reference. Component ~ preferably a vinyl-on-chain diorganopolysiloxane or ~inyl-on-chain diorganosiloxsne blend.
In addition to the foregoing, Component (J) in the form of a hydride cros~-linking agent may be employed.
In a preferred embodiment, Component (J) may be a random copolymer formed of a polydimethyl silo~ane (PD~S) and a polymethyl hydrogen siloxane (PMHS) having the form:
R3SiO(SiORHSiORz)xS iR3 whereln each R i8 independently cho~en from a hydrogen or monovalent hydro~arbon radical free of aliphatic un~aturation containing 1 to about 8 carbon atoms, and x rangeq from about 2 to about 100. ~n the present inv~ntion, Component (J) i8 pre~ent in an amount ranging from about 0.1 to 10 parts by weight based on the pol~mer system, preferably 0.5 to 8, and more preferably 0.8 ~o 2.5 parts by weight. When a hydride agent i5 employed, a platinum cataly~t may be substituted for the peroxide catalyst to cure ths ".
.
. ~ :
6~
- 19 ~ PATENT~
60SI-1$?4 composition. In Component (J) x may vary BO that (J~
ha~ a viscosity ranginy from about 5 to S00 cps, prefer2bly from about 10 to about 100 Cp8 and more preferably from about 10 to 50 CpB at 25C.
S The linear hydride described above can be made by m~ny proced~res which are known in the art and particularly by ~he hydroly~is of appropriate chlorosilane~. See for example, U.S. Patent No.
4,041,101 which is incorporated herein by reference.
In the Example~ below, Component (J) ha~ a viscosity of about 30 centiqtokes, a hydride content of about 0.8 percent by weight, ~nd a chain length of about 100 units.
Component (R) i8 a vinyl terminate~ silazane lS coupling agent and ~urface treatmen~ for the filler which may take the form:
ViSiR2NHSiR2Vi wherein R i~ an organic such a~ CH3. 'rho coupling agent promote~ bonding b~tween gum component~ (A)-(D) of the polymer system ~nd (H) and between the resin components (F) and (H), and m~y be applied to the reinforcing filler, Component (~l), prior to mixing with the other components.
Component (K) may be vinyl stopped linear silazane such a~ tetramethyl-divinyl silazane. The material is added for enhancing the bonding of filler to poly~er.
In the pre~ent in~ention, the silazane also acts as a filler treatment in-situ.
Component (K) is preferably pre~ent in an amount of up to about 2 parts by weight, more preferably up to about a . 3 parts by weight based on the weight of the ~- ~ V 9 ~
- 20 - PAT~N'rS
polymer sy~tem. Component (K) may be pre~ent in an amount o only about 0.03 parts by weight based on 100 parts of the polymer system, how~er, ~l~ghtly higher amount~ are pxeferred.
In addition to, in con~unction with, or in place of Component (K), small amounts of hex~nethyl disilazane may be u~ed to treat fumed silica filler prior to mixing the filler with the other components, or in-~itu. If used, up to about 20 part~ by weight of hexamethyl disilazane i5 added ba~ed on 100 parts of Component (H).
Other componentR may al80 be employed as discussed hereinafter. For example, in order to allow for ea~iex incorporation of the filler in the polymer ~ystem, Component (L), a proce~sing aid or pla~ticizer is employed. In the preferred embodiment, Component (L) i~ a low viscosity silanol or me~hoxy stopped siloxane fluid having a viscosity ranging from about 3-500 cp~
and preferably 3 to 50 Cp8 at 25C. The silox~ne fluid i~ an equilibrium mix of low molecular weight oli~omers of about 4 to about 10 D U~itB ~ pre~erably between 4 and S repea~ing units in length with a minimum amount of cyclic8 in equilibrium with the oligomer~. The proces~ing aid (L) may have the ~orm of ~R2SiOI~2~XOH or (R2SiOI~2)XORl where each R i~ CH~, each Rl is an alkyl, and x i8 between 4 and 10, preferably between 4 and 6, with rs~ulting cyclics of the same number of units in *quilibriumO Di and tri alkoxy terminated siloxanes such a~ trimethoxy siloxane may al~o be used as proce~s aids.
Component (L) may have th~ formula-R30~R2Sio~XR3 ..
.
2~9~ll8 wherein each R is CH3, and x i5 bet~een 4 and 10 and preferably between 4 and 6, with resulting cyclics in the same number of Uni~3 in equilibrium; and ~3 i8 selected from the group consi~ting of alkyl radicals having 1 to about 8 carbon atom~ and hydrogen, with hydrogen being preferred.
In the present invention, the processing aid is pre~ent in amounts between 2 and 10 parts by weight based on the polymer sy~tem, preferably between 2.5 and 5.0 part~ by weight and most preferably about 3.5 part~ by weight based on the polymer 6ystem. It should be understood tha~ typically the more filler tha~ i8 used the greater amount of processing aid i~ employed.
In the Ex~mple~ below, Component (L) has a silanol content of about 7.5 % by weight although a ~ilanol content of about 5 to about 10 weight percent is expected to provide good results.
A ~m~ll amount of water may al80 be added to increase the proce~sibility of the blend. If used, only up to about 0.1 part~ by weight water based on the polymer system i~ uYually employed.
To improve the heat-age resi~tanco o.E the cured composition~ of the presen~ invention, Component (M), a heat~age additive, may be employed. The heat aging component such as fumed TiO2, iron octoate, Ce(OH)4, or mixtuxe~ thereof r may be present in relatively small amount~, e.g., up to 2 parts by weight ba~ed upon the polymer ~ystem. In the example~ below the heat aging Compone~t (~ consist~ of 33 weight percent TiO2, 5 weight percent iron octoate l12% iron in mineral ~pirits), 10 weight percent trea~.ed fumed ~ilica (160 mZ/g), and 50 weight percent of an 800 penetration vinyl-stopped, vinyl-on-chain gum.
-/ . ~
2 ~ 8 60~I-l524 Only up to about two parts by weight Component (M~
i8 needed based on the polymer system to improve the heat-age characteristics of the composition. In the Example~ below, 0.9 and 1.3 part~ by weight of Component (M) are u~ed based on the total weight of the other componen~s.
An acid acceptor, such as MgO or ZnO, Component (N~, may also be added in amounts from 0.5 to about 10 parts by weigh~ ba~ed on th~ polymer ~ys~em. This acid could otherwi~e cause cleavage of the product matrix.
In the Examples below, 1.0 parts by weight of MgO
masterbatch which comprises about 25% MgO in a methyl vinyl poly-siloxane is used for Component (N) based on the polymer system.
Other components which may be added to the blends of the present invention include, but are not limited to:
(O) a heat-age additive comprising cerium hydroxide, preferably about 75% by weight, ~0 mastQrbatched in polydimethylsiloxane fluid havln~ a viscosity of about 30,000 cp~ at 25C.
(P) which is a coloring agent comprising 57~
carbon black di~persed in v~nyl-polydimethyl siloxane ~luid available as K8124 ~rom Kenrich Petrochemical~, 25 Bayonne, New Jersey; and ~ Q) which is zinc oxide ~ZnO) added as an ~mphoteric scavenger for Lmproving resi~tance to lubricating oils.
I~ order to form a heat curable rubber, an organic peroxide, free radical initiator or curing cataly~t is provided. The preferred peroxide curing agents are thermal decomposition organic peroxides conveniently used to cure silicone elastomers. Examples of suitable : ' : ~ ~ :
~9~
- 23 - PAT$~TS
organi~ peroxide free radical initiators for use in the present invention are disclosedr for example, in U.S.
Patent No. 4,S39,357 to Bobear which i8 incorporated herein by reference. Suitable peroxide catalysts include dialkyl peroxide such a~ di-tertiary-butyl peroxide, tertiaxy-butyl-triethylmethyl peroxide, di-tertiary-butyl-tertiary-triphenyl peroxide, t-butyl perbenzoate and a di-tertiary alkyl peroxide such as dicumyl peroxide. Under certain condition~ hereinafter de~cribed, such as when a hydride is used, a platinum catalyst may be employed instead as an initiator. In the examples below, the preferred catalyst is a vinyl specific catalyst such a~ 2,S dimethyl-2,5-di~t-butyl peroxy~ hexane i.e., Lupersol ~101 available from Lu~idol, Corp., Buffalo, New York, herein referred to as Component (R).
In the Example~ below, Componen~ (S~ is the cataly3 Lupersol~ 101 in a masterbatch comprising 33%
Lupersol~ 101, 33~ calcium carbonate and 33~ dLmethyl~
siloxane oil having a ~i3c08ity of 30,000 c~nti~tokes.
Freqllently used thermal decomposition catalysts activate within a temperature range of about 330F to about 390F.
~S
The following Examples shown below used components mixed in various proportions to produce heat curable silicone rubber compositions.
EXAM~PLE5 I -~IV
The Components tA)-(S) were mixed in various proportions to produce the compositions of Examples I-IV listed below in Table I. In each Example, : . . .
4 l~ ~
- 2 4 ~ PATENTS
Components (A) - ( L) were mixed prior to adding the remaining components. The component~ are expressed in part~ by weight.
Example Component I II III IV
( Bl ~ 85 -- 85 (Cl) 5 - 5 (B2) _ 65 _ 65 10 (A~) ~ 20 - 20 (C2) - 15 - 15 (F) 10 - 10 ~ G) 29 . 0 29 .1 - -(H) 30 36 30 36 15 (J) 1.4 1.2 1.4 1.2 (K) 0.12 0.06 0.12 0.06 (L) 3 3 3 3 : :
(~q) o.g 1.3 0.9 1.3 (N) 1.4 2.6 1.4 2.6 2Q (O) 0~ 9 0 . 9 - ~.
(P) 0.4 0.7~ 0.4 0.72 (Q) 5.6 - 5.6 -( R) - 0 . 57 - 0 . 57 (S) 1.5 - 1.5 ~ L 8 s~
- ;2 5 - PA'rBN~S
1~ 2 4 Table II bxlc:w shs~w~ th~ prop~rt~s of the composition~ o~ }~X~lmple8 I-IV after adding all components arld curinçT. All cure cond~ tions were with a peroxide ::atalyst. The compe~itionE~ of th~ Example3 5 were molded at 350~F for 15 minutes.
ExamE~e Pre~erty I I I ~a. IV
Shore A 59 54 49 4S
10 Tensile, p~i 1210 10471367 14~4 E:longation, % 709 748 767 849 ~-Tear-~, ppi 120 202 257 Z23 8p- gr~lrity 1.291 1.252 1~1701.170 Comp. Set, ~ le.d. 38.717~1 33.6 15 T0~t data were obtained f .rom thQ f ollowlng A5~l methods and procedures: Shore A - D-2240; Ten~ile, Elong2tion and Modulus - D-4 12 ~ D~e C ); Te4r - D-624 (Dio 1~); and Compression Set - D-395 ~Method B 22 hrs ~ 350F) T~ble II~ shows khe change in propertie~3 of the -~
20 compo~ition~ of Ex~mple3 I-IV after a 70 hour oil immer~ion at 300 np in a 5W-30 m~tor c;il per ~5~ D-471 .
:: .
; .
2~2~8 - 26 - PA~ENTS
TABLE III
Example Property I II III IV
Shore A -17 -21 -l9 -20 Tensile -27.3 -30.2 -51.1 -56.5 ~ change Elongation -lO.0 -18.1 -34.9 -41.0 % change Weight 20.5 22.7 25.4 29.3 ~ change Volume 30.3 32~0 34.9 38.6 % change Table IV below shows the ch~nge in properties of the compo~itions of Example I-IV after immersion in ASTX
reference oil #3 for 70 hours at 300F per AST~ test method D-471.
T~ LE IY
Example ,, ,~
Property I II ~I IV
20 Shore A -19 -23 -19 -14 Tensile -35.4 -36.1 -63.S -72.7 ~ chang~
Elongation -23.1 -26.1 -53.5 -33.0 % chang~
25 Weight 27.6 2g.8 36.7 39~8 % change Volume 39.2 42.5 47.4 49.0 % change .: .... ,: -, , :
:: :. . : ~ ~-, ' 2~2~8 .
- 27 - PA~ENTS
The compositions of Examplas I and II exhibit enhanced properties which make them useful for many automoti~e gasketing applications. As can be seen in Table III, 10i3ses in tensile strength and elongation are significantly impro~ed and volume swell and weight changes are siynificantly decreased in the compositionis containing the pota88ium al~minosilicate filler after oil immersion testing of the compositions. The observed trend is an improvement in shrinkage resistance and heat age and oil immersion resistance by the inclusion of Component (G).
Although the present invention has been described in connection with preferred embodLmentis, it will be appre-ciated by those skilled in the art that additions, modi-fîcations, substitutions and deletions no~ specificallydescribed may be made without departing from the spirit and scope of thie invention defined in the appended claims.
Claims (30)
1. A heat cured silicone rubber composition comprising a polymer system, said polymer system containing:
(A) up to 100 parts by weight of an organopolysiloxane having a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C and substantially no vinyl, or mixtures of such organopolysiloxanes;
(B) up to 100 parts by weight of a vinyl-stopped organopolysiloxane, substantially free of vinyl-on-chain, having a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C, or mixtures of such organopolysiloxanes;
(C) up to 100 parts by weight of a vinyl-on-chain organopolysiloxane, free of vinyl end stops, having a vinyl content of about 5x10-3 to about 5 weight percent and a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C, or mixtures of such organopolysiloxanes;
(D) up to 100 parts of a vinyl-stopped, vinyl-on-chain organopolysiloxane having a vinyl content of about 5x10-3 to about 5 weight percent, or mixtures of such organopolysiloxanes;
(F) up to about 30 parts by weight based upon 100 parts of the total of Components (A)-(D) of an organopolysiloxane resin copolymer comprising:
1) R3SiO1/2 units (M units) and SiO2 units (Q
units) where each R is independently selected from the group consisting of vinyl radicals and monovalent hydrocarbon radicals free of aliphatic unsaturation with a ratio of M units to Q units ranging from 0.5:1 to about 1.5:1, where the copolymer contains from about 0.5 to 10 weight percent vinyl groups, or
(A) up to 100 parts by weight of an organopolysiloxane having a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C and substantially no vinyl, or mixtures of such organopolysiloxanes;
(B) up to 100 parts by weight of a vinyl-stopped organopolysiloxane, substantially free of vinyl-on-chain, having a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C, or mixtures of such organopolysiloxanes;
(C) up to 100 parts by weight of a vinyl-on-chain organopolysiloxane, free of vinyl end stops, having a vinyl content of about 5x10-3 to about 5 weight percent and a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C, or mixtures of such organopolysiloxanes;
(D) up to 100 parts of a vinyl-stopped, vinyl-on-chain organopolysiloxane having a vinyl content of about 5x10-3 to about 5 weight percent, or mixtures of such organopolysiloxanes;
(F) up to about 30 parts by weight based upon 100 parts of the total of Components (A)-(D) of an organopolysiloxane resin copolymer comprising:
1) R3SiO1/2 units (M units) and SiO2 units (Q
units) where each R is independently selected from the group consisting of vinyl radicals and monovalent hydrocarbon radicals free of aliphatic unsaturation with a ratio of M units to Q units ranging from 0.5:1 to about 1.5:1, where the copolymer contains from about 0.5 to 10 weight percent vinyl groups, or
2) R3SiO1/2 units (M units), SiO2 units (Q units) and RVi2SiO2/2 units (D vinyl units) where each R is as defined above and each RVi is a vinyl containing radical having from 2 to about 10 carbon atoms, and where the ratio of M units to Q units is from 0.5:1 to about 1.5:1, and the D vinyl units are present up to about 70 mol percent based upon the total number of mols of siloxy units in the copolymer, and where the resinous copolymer contains from about 0.5 to about 10.0 weight percent vinyl groups, or
3) mixtures of 1 and 2;
such that the total of Components (A)-(F) equals 100 parts by weight, said silicone rubber composition further comprising:
(G) from about 1 to about 50 parts by weight potassium aluminosilicate filler having a surface area of between about 5.0 and about 6.50 m2/g, an average particle diameter of between about 1.0 and about 20.0 micrometers and an average particle thickness of between about 0.5 and 1.0 micrometers;
(H) up to about 200 parts by weight based upon the polymer system of a finely divided filler; and (J) from about 0.1 to about 10 parts by weight based upon the polymer system of a hydride cross-linking agent.
2. The heat cured silicone rubber composition of claim 1, wherein Component (G) is present in an amount of between about 10 and about 40 parts by weight.
3. The heat cured silicone rubber composition of claim 1, wherein Component (G) is present in an amount of between about 15 and about 30 parts by weight.
such that the total of Components (A)-(F) equals 100 parts by weight, said silicone rubber composition further comprising:
(G) from about 1 to about 50 parts by weight potassium aluminosilicate filler having a surface area of between about 5.0 and about 6.50 m2/g, an average particle diameter of between about 1.0 and about 20.0 micrometers and an average particle thickness of between about 0.5 and 1.0 micrometers;
(H) up to about 200 parts by weight based upon the polymer system of a finely divided filler; and (J) from about 0.1 to about 10 parts by weight based upon the polymer system of a hydride cross-linking agent.
2. The heat cured silicone rubber composition of claim 1, wherein Component (G) is present in an amount of between about 10 and about 40 parts by weight.
3. The heat cured silicone rubber composition of claim 1, wherein Component (G) is present in an amount of between about 15 and about 30 parts by weight.
4. The heat cured silicone rubber composition of claim 1, wherein Component (G) has a surface area of from about 5.05 to about 6.2 m2/g.
5. The heat cured silicone rubber composition of claim 1, wherein Component (G) has a surface area of from about 5.07 to about 6.11 m2/g.
6. The heat cured silicone rubber composition of claim 1, wherein Component (G) has an average particle diameter of from about 1.0 to about 10 micrometers.
7. The heat cured silicone rubber composition of claim 1, wherein Component (G) has an average particle diameter of from about 1.0 to about 5.0 micrometers.
8. The heat cured silicone rubber composition of claim 1, wherein Component (G) has an average particle thickness of from about 0.5 to about 0.8 micrometers.
9. The heat cured silicone rubber composition of claim 1, wherein Component (G) has an average particle thickness of from about 0.45 to about 0.55 micrometers.
10. The heat cured silicone rubber composition of claim 1, wherein Component (B) has the structure:
ViSiOR12 (SiOR12)x(SiOR22)y SiR12Vi;
wherein Vi is vinyl and each R1 is independently chosen from monovalent hydrocarbon free radicals free of aliphatic unsaturation and containing 1 to about 8 carbon atom;
PATENTS
each R2 is independently chosen from monovalent hydrocarbon radicals containing 1 to about 8 carbon atoms, and x and y are integers chosen such that the viscosity is about 3,000,000 to about 100,000,000 cps at 25°C.
ViSiOR12 (SiOR12)x(SiOR22)y SiR12Vi;
wherein Vi is vinyl and each R1 is independently chosen from monovalent hydrocarbon free radicals free of aliphatic unsaturation and containing 1 to about 8 carbon atom;
PATENTS
each R2 is independently chosen from monovalent hydrocarbon radicals containing 1 to about 8 carbon atoms, and x and y are integers chosen such that the viscosity is about 3,000,000 to about 100,000,000 cps at 25°C.
11. The heat cured silicone rubber composition of claim 1, wherein Component (D) has the formula:
ViSiOR12 (SiOR1RVi)x(SiOR22)y SiR12Vi wherein Vi is vinyl, RV1 is a vinyl radical having from 2 to about 10 carbon atoms, each R1 is independently chosen from a vinyl radical having from 2 to about 10 carbon atoms, and a monovalent hydrocarbon free radicals free of aliphatic unsaturation and containing 1 to about 8 carbon atoms, each R2 is independently chosen from a vinyl radical having from 2 to about 10 carbon atoms, and a monovalent hydrocarbon free radicals free of aliphatic unsaturation and containing 1 to about 8 carbon atoms, and x and y are integers, wherein x, y, RV1, R1 and R2 are chosen such that Component (D) has a weight percent vinyl concentration in the range from about 0.001 to about 5 weight percent.
ViSiOR12 (SiOR1RVi)x(SiOR22)y SiR12Vi wherein Vi is vinyl, RV1 is a vinyl radical having from 2 to about 10 carbon atoms, each R1 is independently chosen from a vinyl radical having from 2 to about 10 carbon atoms, and a monovalent hydrocarbon free radicals free of aliphatic unsaturation and containing 1 to about 8 carbon atoms, each R2 is independently chosen from a vinyl radical having from 2 to about 10 carbon atoms, and a monovalent hydrocarbon free radicals free of aliphatic unsaturation and containing 1 to about 8 carbon atoms, and x and y are integers, wherein x, y, RV1, R1 and R2 are chosen such that Component (D) has a weight percent vinyl concentration in the range from about 0.001 to about 5 weight percent.
12. The heat cured silicone rubber composition of claim 1, further comprising:
(K) up to about 2 parts by weight of a tetramethyl-divinyl silazane based on 100 parts by weight of the polymer system.
(K) up to about 2 parts by weight of a tetramethyl-divinyl silazane based on 100 parts by weight of the polymer system.
13. The heat cured silicone rubber composition of claim 1, further comprising:
(L) up to about 10 parts by weight based upon the polymer system of a silanol stopped siloxane fluid having a viscosity of about 3 to about 500 cps at 25°C.
(L) up to about 10 parts by weight based upon the polymer system of a silanol stopped siloxane fluid having a viscosity of about 3 to about 500 cps at 25°C.
14. The heat cured silicone rubber composition of claim 1, wherein said filler, Component (H), is treated with up to about 20 parts by weight, based on 100 parts by weight of Component (H), of cyclic ethyl tetramer.
15. The heat cured silicone rubber composition of claim 3, wherein Component (D) has a vinyl content of about 0.301 weight percent or higher and is present in an amount of between about 0.1 and about 100 percent of the polymer system.
16. The heat cured silicone rubber composition of claim l, wherein Component (J), is an organohydrogen-siloxane cross-linking agent having a hydride content of about 0.8 percent by weight.
17. The heat cured silicone rubber composition of claim 1, wherein Component (J) has the formula:
R3SiO(SiORHSiOR2)xSiR3 wherein each R is independently chosen from a hydrogen or monovalent hydrocarbon radical free of aliphatic unsaturation containing 1 to about 8 carbon atoms, and x varies 80 that (J) has a viscosity ranging from about 5 to 500 cps at 25°C.
R3SiO(SiORHSiOR2)xSiR3 wherein each R is independently chosen from a hydrogen or monovalent hydrocarbon radical free of aliphatic unsaturation containing 1 to about 8 carbon atoms, and x varies 80 that (J) has a viscosity ranging from about 5 to 500 cps at 25°C.
18. The heat cured silicone rubber composition of claim 1, further comprising Component (M) up to about 2 parts by weight based upon the polymer system of a heat-age additive.
19. The heat cured silicone rubber composition of claim 1, further comprising Component (N), up to about 10 parts based on the polymer system of an acid acceptor.
20. The heat cured silicone rubber composition of claim 1, wherein the filler (H) has a surface area of between about 160 and about 240 m2/g.
21. A heat cured silicone rubber gasket comprising a polymer system, said polymer system containing:
(A) up to 100 parts by weight of an organopolysiloxane having a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C and substantially no vinyl, or mixtures of such organopolysiloxanes;
(B) up to 100 parts by weight of a vinyl-stopped organopolysiloxane, substantially free of vinyl-on-chain, having a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C, or mixtures of such organopolysiloxanes;
(C) up to 100 parts by weight of a vinyl-on-chain organopolysiloxane, free of vinyl end stops, having a vinyl content of about 5x10-3 to about 5 weight percent and a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C, or mixtures of such organopolysiloxanes;
(D) up to 100 parts of a vinyl-stopped, vinyl-on-chain organopolysiloxane having a vinyl content of about 5x10-3 to about 5 weight percent, or mixtures of such organopolysiloxanes;
(F) up to about 30 parts by weight based upon 100 parts of the total of Components (A)-(D) of an organopolysiloxane resin copolymer comprising:
1) R3SiO1/2 units (M units) and SiO2 units (Q
units) where each R is independently selected from the group consisting of vinyl radicals and monovalent hydrocarbon radicals free of aliphatic unsaturation with a ratio of M units to Q units ranging from 0.5:1 to about 1.5:1, where the copolymer contains from about 0.5 to 10 weight percent vinyl groups, or 2) R3SiO1/2 units (M units), SiO2 units (Q units) and RVi2SiO2/2 units (D vinyl units) where each R is as defined above and each RVi is a vinyl containing radical having from 2 to about 10 carbon atoms, and where the ratio of M units to Q units is from 0.501 to about 1.5:1, and the D vinyl units are present up to about 70 mol percent based upon the total number of mols of siloxy units in the copolymer, and where the resinous copolymer contains from about 0.5 to about 10.0 weight percent vinyl groups, or 3) mixtures of 1 and 2;
such that the total of Components (A)-(F) equals 100 parts by weight, said silicone rubber composition further comprising:
(G) from about 1 to about 50 parts by weight potassium aluminosilicate filler having a surface area of between about 5.0 and about 6.50 m2/g, an average particle diameter of between about 1.0 and about 20.0 micrometers and an average particle thickness of between about 0.5 and 1.0 micrometers;
(H) up to about 200 parts by weight based upon the polymer system of a finely divided filler; and (J) from about 0.1 to about 10 parts by weight based upon the polymer system of a hydride cross-linking agent.
(A) up to 100 parts by weight of an organopolysiloxane having a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C and substantially no vinyl, or mixtures of such organopolysiloxanes;
(B) up to 100 parts by weight of a vinyl-stopped organopolysiloxane, substantially free of vinyl-on-chain, having a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C, or mixtures of such organopolysiloxanes;
(C) up to 100 parts by weight of a vinyl-on-chain organopolysiloxane, free of vinyl end stops, having a vinyl content of about 5x10-3 to about 5 weight percent and a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C, or mixtures of such organopolysiloxanes;
(D) up to 100 parts of a vinyl-stopped, vinyl-on-chain organopolysiloxane having a vinyl content of about 5x10-3 to about 5 weight percent, or mixtures of such organopolysiloxanes;
(F) up to about 30 parts by weight based upon 100 parts of the total of Components (A)-(D) of an organopolysiloxane resin copolymer comprising:
1) R3SiO1/2 units (M units) and SiO2 units (Q
units) where each R is independently selected from the group consisting of vinyl radicals and monovalent hydrocarbon radicals free of aliphatic unsaturation with a ratio of M units to Q units ranging from 0.5:1 to about 1.5:1, where the copolymer contains from about 0.5 to 10 weight percent vinyl groups, or 2) R3SiO1/2 units (M units), SiO2 units (Q units) and RVi2SiO2/2 units (D vinyl units) where each R is as defined above and each RVi is a vinyl containing radical having from 2 to about 10 carbon atoms, and where the ratio of M units to Q units is from 0.501 to about 1.5:1, and the D vinyl units are present up to about 70 mol percent based upon the total number of mols of siloxy units in the copolymer, and where the resinous copolymer contains from about 0.5 to about 10.0 weight percent vinyl groups, or 3) mixtures of 1 and 2;
such that the total of Components (A)-(F) equals 100 parts by weight, said silicone rubber composition further comprising:
(G) from about 1 to about 50 parts by weight potassium aluminosilicate filler having a surface area of between about 5.0 and about 6.50 m2/g, an average particle diameter of between about 1.0 and about 20.0 micrometers and an average particle thickness of between about 0.5 and 1.0 micrometers;
(H) up to about 200 parts by weight based upon the polymer system of a finely divided filler; and (J) from about 0.1 to about 10 parts by weight based upon the polymer system of a hydride cross-linking agent.
22. The heat cured silicone rubber gasket of claim 24, wherein Component (G) has a surface area of from about 5.05 to about 6.2 m2/g.
23. The heat cured silicone rubber gasket of claim
24, wherein Component (G) has a surface area of from about 5.07 to about 6.11 m2/g.
24. The heat cured silicone rubber gasket of claim 24, wherein Component (G) has an average particle diameter of from about 1.0 to about 10 micrometers.
24. The heat cured silicone rubber gasket of claim 24, wherein Component (G) has an average particle diameter of from about 1.0 to about 10 micrometers.
25. The heat cured silicone rubber gasket of claim 24, wherein Component (G) has an average particle diameter of from about 1.0 to about 5.0 micrometers.
26 . The heat cured silicone rubber gasket of claim 24, wherein Component (G) has an average particle thickness of from about 0.5 to about 0.8 micrometers.
27. The heat cured silicone rubber gasket of claim 24, wherein Component (G) has an average particle thickness of from about 0.45 to about 0.55 micrometers.
28. A method of improving oil resistance in a heat curable silicone rubber composition, said silicone rubber composition comprising a polymer system, said polymer system containing:
(A) up to 100 parts by weight of an organopolysiloxane having a viscosity of about 3,000,000 to about 100,000/000 cps at 25°C and substantially no vinyl, or mixtures of such organopolysiloxanes;
(B) up to 100 parts by weight of a vinyl-stopped organopolysiloxane, substantially free of vinyl-on-chain, having a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C, or mixtures of such organopolysiloxanes;
(C) up to 100 parts by weight of a vinyl-on-chain organopolysiloxane, free of vinyl end stops, having a vinyl content of about 5x10-3 to about 5 weight percent and a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C, or mixtures of such organopolysiloxanes;
(D) up to 100 parts of a vinyl-stopped, vinyl-on-chain organopolysiloxane having a vinyl content of about 5x10-3 to about 5 weight percent, or mixtures of such organopolysiloxanes (F) up to about 30 parts by weight based upon 100 parts of the total of Components (A)-(D) of an organopolysiloxane resin copolymer comprising:
1) R3SiO1/2 units (M units) and SiO2 units (Q
units) where each R is independently selected from the group consisting of vinyl radicals and monovalent hydrocarbon radicals free of aliphatic unsaturation with a ratio of M units to Q units ranging from 0.5:1 to about 1.5:1, where the copolymer contains from about 0.5 to 10 weight percent vinyl groups, or 2) R3SiO1/2 units (M units), SiO2 units (Q units) and RVi2SiO2/2 units (D vinyl units) where each R is as defined above and each RVi is a vinyl containing radical having from 2 to about 10 carbon atoms, and where the ratio of M units to Q units is from 0.5:1 to about 1.5:1, and the D vinyl units are present up to about 70 mol percent based upon the total number of mols of siloxy units in the copolymer, and where the resinous copolymer contains from about 0.5 to about 10.0 weight percent vinyl groups, or 3) mixture of 1 and 2;
such that the total of Components (A)-(F) equals 100 parts by weight, said silicone rubber composition further comprising:
(H) up to about 200 parts by weight based upon the polymer system of a finely divided filler; and (J) from about 0.1 to about 10 parts by weight based upon the polymer system of a hydride cross-linking agent, said method comprising mixing with said silicone rubber composition (G) from about 1 to about 50 parts by weight potassium aluminosilicate filler having a surface area of between about 5.0 and about 6.50 m2/g, an average particle diameter of between about 1.0 and about 20.0 micrometers and an average particle thickness of between about 0.5 and 1.0 micrometers.
(A) up to 100 parts by weight of an organopolysiloxane having a viscosity of about 3,000,000 to about 100,000/000 cps at 25°C and substantially no vinyl, or mixtures of such organopolysiloxanes;
(B) up to 100 parts by weight of a vinyl-stopped organopolysiloxane, substantially free of vinyl-on-chain, having a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C, or mixtures of such organopolysiloxanes;
(C) up to 100 parts by weight of a vinyl-on-chain organopolysiloxane, free of vinyl end stops, having a vinyl content of about 5x10-3 to about 5 weight percent and a viscosity of about 3,000,000 to about 100,000,000 cps at 25°C, or mixtures of such organopolysiloxanes;
(D) up to 100 parts of a vinyl-stopped, vinyl-on-chain organopolysiloxane having a vinyl content of about 5x10-3 to about 5 weight percent, or mixtures of such organopolysiloxanes (F) up to about 30 parts by weight based upon 100 parts of the total of Components (A)-(D) of an organopolysiloxane resin copolymer comprising:
1) R3SiO1/2 units (M units) and SiO2 units (Q
units) where each R is independently selected from the group consisting of vinyl radicals and monovalent hydrocarbon radicals free of aliphatic unsaturation with a ratio of M units to Q units ranging from 0.5:1 to about 1.5:1, where the copolymer contains from about 0.5 to 10 weight percent vinyl groups, or 2) R3SiO1/2 units (M units), SiO2 units (Q units) and RVi2SiO2/2 units (D vinyl units) where each R is as defined above and each RVi is a vinyl containing radical having from 2 to about 10 carbon atoms, and where the ratio of M units to Q units is from 0.5:1 to about 1.5:1, and the D vinyl units are present up to about 70 mol percent based upon the total number of mols of siloxy units in the copolymer, and where the resinous copolymer contains from about 0.5 to about 10.0 weight percent vinyl groups, or 3) mixture of 1 and 2;
such that the total of Components (A)-(F) equals 100 parts by weight, said silicone rubber composition further comprising:
(H) up to about 200 parts by weight based upon the polymer system of a finely divided filler; and (J) from about 0.1 to about 10 parts by weight based upon the polymer system of a hydride cross-linking agent, said method comprising mixing with said silicone rubber composition (G) from about 1 to about 50 parts by weight potassium aluminosilicate filler having a surface area of between about 5.0 and about 6.50 m2/g, an average particle diameter of between about 1.0 and about 20.0 micrometers and an average particle thickness of between about 0.5 and 1.0 micrometers.
29. A method as defined in claim 31, further comprising adding a catalytic amount of a curing catalyst to said composition and curing said composition.
30. The invention as defined in any of the preceding claims including any further features of novelty disclosed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/865,564 US5815597A (en) | 1992-04-09 | 1992-04-09 | Binary encoding of gray scale nonlinear joint transform correlators |
| US865,546 | 1992-04-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2092448A1 true CA2092448A1 (en) | 1993-10-10 |
Family
ID=25345792
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002092448A Abandoned CA2092448A1 (en) | 1992-04-09 | 1993-03-25 | Heat cured silicone rubber compositions containing a potassium aluminosilicate filler which provides resistance to hydrocarbon oils and adjustable shrinkage |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US5815597A (en) |
| CA (1) | CA2092448A1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6163403A (en) * | 1998-07-30 | 2000-12-19 | Litton Systems, Inc. | High output reflective optical correlator having a folded optical axis using grayscale spatial light modulators |
| GB2341965A (en) * | 1998-09-24 | 2000-03-29 | Secr Defence | Pattern recognition |
| US6567566B1 (en) * | 1999-04-27 | 2003-05-20 | The United States Of America As Represented By The Secretary Of The Air Force | Techniques to improve binary joint transform correlator, particularly for fingerprint recognition |
| US6744909B1 (en) | 1999-08-19 | 2004-06-01 | Physical Optics Corporation | Authentication system and method |
| US7058221B1 (en) * | 2000-07-07 | 2006-06-06 | Tani Electronics Industry Co., Ltd. | Method of recognizing object based on pattern matching and medium for recording computer program having same |
| CN100389427C (en) * | 2006-04-13 | 2008-05-21 | 湖南童森科技有限公司 | Method and device for improving anti-damage of word and image in machine readable tag |
| US9762565B2 (en) * | 2015-06-26 | 2017-09-12 | Washington State University | Spatial-light-modulator-based signatures of intrinsic and extrinsic scattering surface markers for secure authentication |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4949389A (en) * | 1987-10-09 | 1990-08-14 | The United States Of America As Represented By The United States Department Of Energy | Optical ranked-order filtering using threshold decomposition |
| US4832447A (en) * | 1987-12-04 | 1989-05-23 | Board Of Trustees Operating Michigan State University | Joint transform image correlation using a nonlinear spatial light modulator at the fourier plane |
| US5040140A (en) * | 1989-04-28 | 1991-08-13 | The United States Of America As Represented By The Secretary Of The Air Force | Single SLM joint transform correaltors |
| US5119443A (en) * | 1990-06-14 | 1992-06-02 | Bahram Javidi | Nonlinear joint transform optical correlator having varying degrees of nonlinearity |
-
1992
- 1992-04-09 US US07/865,564 patent/US5815597A/en not_active Expired - Fee Related
-
1993
- 1993-03-25 CA CA002092448A patent/CA2092448A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| US5815597A (en) | 1998-09-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5380770A (en) | Heat cured silicone rubber compositions containing a potassium aluminosilicate filler which provides resistance to hydrocarbon oils and adjustable shrinkage | |
| US2890188A (en) | Siloxane elastomers compounded with hydroxylated silanes | |
| CA1315453C (en) | Method for preparing clear polyorganosiloxane elastomers | |
| US5082886A (en) | Low compression set, oil and fuel resistant, liquid injection moldable, silicone rubber | |
| EP0581504B1 (en) | Self-adhering silicone rubber with low compression set | |
| CA2007660C (en) | Elastomer-forming compositions | |
| US5081172A (en) | Method to reduce compression set in silanol-containing silicone elastomer bases | |
| CA1192694A (en) | High strength curable silicone rubber compositions | |
| US4724167A (en) | Treated silica fillers and process for making the same | |
| CA2085673A1 (en) | Low compression set silicone elastomers | |
| US5854310A (en) | Curable fluorosilicone composition having improved lubricity | |
| US5674935A (en) | Vinyl-containing silanol-terminated silicone compositions for treatment of fillers | |
| US5206329A (en) | One part heat curable organopolysiloxane compositions | |
| CA1337226C (en) | Paintable organopolysiloxane compositions which crosslink at room temperature to form elastomers | |
| CA2092448A1 (en) | Heat cured silicone rubber compositions containing a potassium aluminosilicate filler which provides resistance to hydrocarbon oils and adjustable shrinkage | |
| CA2097015A1 (en) | Low modulus room-temperature-curable organosiloxane composition | |
| CA1138592A (en) | Oxygen-curable mercaptoorganosiloxane compositions catalyzed by cobaltocene compounds and method of forming higher molecular weight products therefrom | |
| EP0577357A2 (en) | Silicone elastomer compositions | |
| CA2092457A1 (en) | Oil resistant heat cured elastomer compositions with mixed metal oxides | |
| GB2284214A (en) | Silicone and fluorosilicone heat cured filled rubber compositions | |
| EP0584354B1 (en) | Clear heat curable silicone rubber compositions with resin for matching refractive index | |
| US5994456A (en) | Compositions comprising mercapto-functional organosilicon compounds | |
| JP2790592B2 (en) | Thermoset silicone rubber composition with simplified composition | |
| AU611245B2 (en) | Silicone rubber containing alkali metal salts of phosphoric acid and phosphorous acid and compositions therefor | |
| JP2675505B2 (en) | Improved thermosetting silicone rubber composition using vinyl group containing MQ resin and vinyl end group containing homopolymer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |