CA2050337A1 - High molecular weight binders for magnetic recording media - Google Patents
High molecular weight binders for magnetic recording mediaInfo
- Publication number
- CA2050337A1 CA2050337A1 CA002050337A CA2050337A CA2050337A1 CA 2050337 A1 CA2050337 A1 CA 2050337A1 CA 002050337 A CA002050337 A CA 002050337A CA 2050337 A CA2050337 A CA 2050337A CA 2050337 A1 CA2050337 A1 CA 2050337A1
- Authority
- CA
- Canada
- Prior art keywords
- recording medium
- segment
- binder
- magnetic
- binder composition
- 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
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
- G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
- G11B5/702—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the bonding agent
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S428/00—Stock material or miscellaneous articles
- Y10S428/90—Magnetic feature
Abstract
The present invention provides an improved magnetic recording medium comprising a non-magnetic support with at least one magnetic layer comprising a magnetizable pigment dispersed in a binder composition. The binder composition of the present invention comprises a block copolymer, having a hard segment, with a glass transition temperature (Tg) of greater than about 70·C, and a soft segment, having a Tg of less than about -30·C. The binder composition of the present invention has relatively stable physical properties over a range of temperatures, preferably at least 50·C and more preferably at least 100·C.
Description
i~j WO9~/14662 ,,~ fl~, PCT/US90/02792 ~?~s ."jl f, .. . . . .
' XIGH MOL~CULAR WEIGHT BINDERS ~OR
: , MAGNETIC RECORDING ~EDIA - - .
~"' 5 ' ''' ~ ' , ' , :
:.. `; The present in~ention relates to magnetic media 'and particularly to,~n Lmproved,magnetic media made from ,~,high molecular veight materials., :.: 10 Backqround of the Invention .,.. -., - ~ . . -;: ' The use of magnetizable particles ,affixed. to various substrates,to record, store, and reuse information ~`. con~inues to increase. The various forms of magne~izable ~, particles affixed to a substrate, often,termed magnetic ~,.. 15 medià, include, audio tapes,; video tapes,, computer : , diskettes, computer tapes, data.cartridges and many other `,' product~. In each of these constructions, magnetic particles are ~ound to a -substrate and,-information~is ': recorded ànd stored ,1;n.,the. magnetizable ~particles .for ~ . : ~ ... .....
. 20 later retrieval and use. , , . - , , '- ~ , : ~agnetic media must por?sess certain,physical and -.
,,; magnetic properties,to be su.itable for .-,use with the ,... ; various, magnetic reading.,and recording devices.;~ .Thesuraca of the media,must be suficiently~.,smooth r 80 ~ that ~' 25~ when read b,y the magnetic head,the recorded,signal.is,read`~. aecuràtely. ~perities or roughness in.the-media surface ~' can result in unaccept~ble ~levels.,of~.aignal, to~noise :~:. ratio. The media must also,be very durable.... -i~,It;~must~be ' able"to record and reproduce information repeatedly~
30 preferably ~housands,.i~not.~illions,of,;,,,time~. To be durable" the magnetic .~particl,eLs ,~must be,~-firmly~bound:3to~f;
$he sub&?txate;jand5;not,.,-be woJrn.~ff~,by.~the~.pa,ssing.,of~he '.'~ ma ~etic~ head~.,over.. the.~media. r~ ~In ~,addit~ion,1i-,it~is ~important that:the media have.sufficient~Llubricity,60~that '.''~35 the ma ~ etic.,jhead~passes .fr,,ee~ly~o~v,,er~the,~surfac.e:with a~
jm, ~i~n3~J~5, ",cit,~oef,"i~ci~eunt~o~f,,~f,~r~iAct,ion~ p.re,,f~erablyl~ithout~:the~~
neces6ity.~ f ~added~lubricanks.~ r~ nother~i portant charac~erls~tic ~o,~ a~m~agnet~c~m,edia~!is .that,~,,it.ihave very uniform phy~ical properties over a wide temperature range, .
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; . :1'." ,~,, ~ WO90/14662 2~503~j7! ~ PCT/US90/02792 ;' ` 2 such as a range of 100 C.
Typically, a magnetic- media is produced by passing a non-magnetic support through an apparatus which coats the support with a liquid dispersion of the magnetic layer. This di~persion consists of a binder, in either an uncured 'or solvated state',' ha~ing the~ magnetizable particles homogeneously dispèrsed therein. After coating, the dispersion dries or cures leaving a tough binder film having the magneti~able particleis unifo~mly distributed throughout.
- The ~esired physical and magnetic properties are often dictated by certain processing' parameters. One important parameter is good pigment wetting in the bulk - liquid dispersion.-- Good pigment wetting is closely '~
related to disperision stability and both are necessary to insurP evenly distributed pigment throughout the dispersion'and throughout the finished'magnetic coating.
Another important-processing parameter is the so-càlled pot life of the dispersion, t:he tLme for which the ~0 dispersion can be kept sufficiently non-viscous before coating. In general terms, a short pot-life, caused by a fast cure of the binder, creates time'constraints'in the ; coating proce'ss'"'and'problems in;obtaining'a suffic~entlysmooth surface~'bn-the magnetic layer. 'A longer pot-life often requires:a-slowèrlcur2 ratè,'oftèn'resulting in the :coated magnetic layer sùffering~damage as it is passed ;through the coating apparàtus in its insufficièntly~cured ! . .1 A-ma~ority ~f conve~tional mag~etic médiâ binders 30~are derive'd-rom lowër:'molécuîar we`ightimàtërials" ~ ich :~ilrequire'curing''~to~'~;gènera~e~ a3; binder -resin`''having the .Iappropriate:-physical prope~ies'.' In'à~dition to the po~-fe~considerati'ons~discu69ed above,'~the ùise of curable '3 low~ molëcular~ wëig~t ~s~rting materials cà~ càuse 35Yriadditional problëm~ TXe di'spërsion''of the'iow mo~ecular -;.weigh~ materi^als~may prëmaturely gei'or~'cause ~1Cculà~ion ¦ r~ of the magnetic particl~s5rësulting 'in non-ùni~o ~ and . ~
:.~ .
: ': ' . .. , .: ' ~.; WO90/14~2 PCT/US90~02792 337, . i; ~
( '' ' 3 unacceptable magnetic performance of the coatings. In addition, low molecular weight materials may remain in the binder after coating resulting in poor durability of'the magnetic coati~g. Further, low molecular w ight materials left aftPr cusing may migrate to the surface of the mediaj '-' and come into contact with the recording head where they can adversely affect performance through incxeased fxictionl stiction, head clogging, and/or poor blocking resistance.
Other problems encountered by magnetic 'media'-using conventional curable binder systems known in--the prior art include hydrolysis of the binder and degradation of the binder by humidity. In addition, the acti~ation or cure steps required by conventional-binder systems with , 15 curable lower molecular-,weight starting materials create additional complicated and expensive production steps.
,Known, polymerie -binder systems experie~cP a cha~ge - in physical properties over a range' of temperatures. In use, magnetic: media are often exposed to a wide range of te,mperatures, often over a range in excass of 100 C. ,The modulus oi' the binder mat*rial will typ.~ca,lly,,-j~substantially ichange over thi~ ra'nge, ' for ~"', ~ ,example;~from stiff and brittle ~o soft!'and tacky. These changes in physical ;properties can ;cause`'~rp'erformance 25i problems,in~the use of the media;- -~
In;view~of the above~deficiencies-~in-prior'art ; magnetic media binders, there is a need to -provide a binder suitable or use in'-magnetic ~media which is ' co~pri6ed of high molecuiar weigh`t start'ing' materials, 1 30 which do not require polymerization or,'~~crossli~king'to) $~form,~a~isuit~ble:m gneti'cu~coating.'-: In addition, it is dësirable that these hi~h molècular - weight'~binder materials~ provide-~ood:~ pigmenti'wett'ing a~d~ dispersion , ~tability, including systems with~3high'pigment~10a~ings.
~' 35 It i~ also desirable tha~ ~the ma'gnetic ~media ha~e -~-.,excellent,; mechanical~-properties','~r~uch æas'~moothness/
,~durability and--lubricity;,along with excellent~'electrical - , ~, .. .
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~ WO 90/1~62 PCT/US90/02792 , G ;~0 S0337~
properties, such as ~ignal-to-noi^~e ratio. It is al~o desirable that the physical and magnetic propertie~ of the media are relatively uniform throughout a wide range of temperatures. - - --, 5 ~Summary-of the Invsntion -~
; The present inventi~n there~ore- provides an improved magnetic recording :medium comprising a nonmagnetic support with at least one magnetic layer comprising a magnetizable pigment disper6ed~in-a binder composition. The binder composition of :the present inYention comprises a block copolymer, having a hard segment, with,~a gla58 ~ransition temperature (Tg) of greater than about 70 C, and a soft segment, having a Tg of less than about -30 C. ~:-", 15 The binder composition-of the present invention has relat~vely stable ph~sical properties over a range of temperaturesO A plot of the hog of the Modùlus (E'~ in dynes/cm2 ~ersus temperature in degre~s C, gives a plot having a plateau region. The absolute value of the average slope of!the plateau region,-S, is less than 8 X -~`. 10-3~ preferably;less-than~5 ~:10-3, and most preferably less~than 2 ,X, 10-3 ~ The:plateiau,region extends:o~ër a temperature range of at least 50 C, and praferably over a temperatur~,range of at,least lOO~C.~
~he binder compooiition of the present--invention-;
comprises~a block;copolymer~having the follo~ing general , j fo,rmula: 3; ,~'.,-;,~ ' `'.,`. 'i3'~5'.'~;-.-i~ ` `''`"-'`~' '~'-~ ''`~';' '`--'' B -:Y -~(B-~)~; C~J ., ~ f~ n_i'.Lr~b~ J~J~
wherein Y-is~aibsingle~bond or~a mùltifunc`~`ional ~-~ 30,~couplingiag~nt;t~ r -~I~LL~r?~ r~ r~
. A ~iS, a hard ~polymeric~segment ~having'ia~;iTg-Lof ~greater;*han about;-~70C; s~ r~ ?~ aPJ r ~
oi~ B,li a~oft~polymerie segment3hà~ing a ~8fof~1ëss ,han~ ~OUts~!30"C;,r~and,-~ J ,~7r; ~i&~ C~
- 35;~ n is~about 13~to 15-s~3 ~ir~r,r~ . o~ f~ 2 ,.c~,~,,,Glas~ltransition~ emperature.(Tg);isidefinè~-as the temperatuxe~at~which the polymerrchanges from a~"h~rd . .
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W090/14662 i~ 7 PCT/US9~/0~792 ~; . .
... , 5 brittle glassy material to a rubbery or viscous pol~ner.
Brief Description of the Draw~g~
Fi~. 1 is a plot of the Log E'.in dynes/cm2 versus Tempexature in C, for a binder material of the invention.
5Fig. 2 i~ a plot of.the ~og E' in dynes/cm2 versus Temperature in C, for a binder material of the present in~ention. : ~
~ Fig. 3 is a plot.of the hc33g E' in dynes/cm2 versus Tempera~ure in : C, for a comparative ex~nple of aiknown binder ma~erial. .-..`
Fig. 4 is a plot of the Log E' in dynes/cm2 versus Temperature in C, for a comparative example of a known binder material.
.. Detailed Description-of the I~vention . .
.. The present invention provides an improved :magnetic media that utilizes high molecular weight starting materials in a binder composition to secure the magnetizable pigment to a;non-magnetic support. The magnetic media of the present :invention i5 capable of ha~ing excellent electrical prope:rties, such as signal-to-:
.,.nois,e ratio.,,.In addition,.the properties.of the instan~
magnetîc media are very uniforrn over a wide range of temperat,ure6,~,typically.a range-lof~:at'..least 50 C, and ~ preferably~,-at,,least:~.100 C., ~h~3~,magnetic media'`'of-~jthe 25,~,pr~senti;,in,,vention;generally.comprise a ~inder 'material,~
magnetizable,-pigment, ,~and;.additives,:co~ted `on-`a~ non-magnetic suppor~
,, .~ ., ~,.. .
3Ij,.Binder,~ ,"-~ 5 -~ r ' '. 30 The bi~der 3composition ~ comprises.`i-ia~ block copolymer, hav.ing"a.,hard.segment~/~-A,'with7a-T8l~greater than ,a.,bJout"70_C,,andga~soft~,seyment, B; with a:Tg below-~about -~3~330 ,5.~ i~he molecular5,weight-.of the hard ~3egmen~ A,' is , r~pre,ferabl~3,~bout~,~10iOOO;:i~o;35,000,~.and the,softi'~egment, -~ 35,~;B,~preerably^has~a~molecularlweight~of:~about~ll5,'000 to ~ The hard-segment, A, is,:pre'ferably à homopolymer ,, ,. ,, :, ,. ,. , , , , - ... ... .. . . .
.WO~0/a4662 )~ PCT/US9o/0279i Z~ 337~
6 ...
comprised of a monovinyl aromatic monomer. Segment A will typically have a molecular weight of a~out 10,000 to lOO,OOO, and .preferably about~20,000 to 75,000. The monomer, molecular weight,~and polymferiza~ion process of the hard segment is selected such that the Tg of the hard segment A is greater than abou~ 70 C.
The soft segment, B, is preferably a homopolymar comprised of a conjugated diene!.monomer. Seyment B will typically have~a .molecular weight of about 10,-000 to 100,000, and preferably about 15,000 to 75,000. The monomer, molecular weight, and polymerization process off the soft segmfent, B, are selected such that the Tg is below ~bout -30 C. --:
- The-manufacture of block copolymers:is well-known in the art. For sxample, the homogenous A block may be grown as~ifollows~
~ .A* + A~ AA*
An AB block can be grown by adding B to an AA* cha`in as ~ollows: - -. AA* ~ B -> AB* --ThejAB~ chains.will frequently couple together to for~fABA
` ~ bl~ocks . ,i~ ,f ~ J~ r~ r;~ j 3 . .. ~ ii; ~...~f~
A .multifunctional coupling~iagent-can`~also` be added. :to .the.i .systefm to :formf--branched :~or ~ star . j25 r configurations.~ The~predominant~reaction:product ;of`the coupling reaction-resuIts-in~~a ~lock;copolymer-haY`ing the general formula~ e i;i p, '-- B -- Y ~ (B ~ ~n wherein Y is a single bond or a multifun`ctional 30~cc~oupling~agentj~cand n~.is^.about~l to7~15 .~~ ?The-star~iblock coPolymer eomponent (n:- 2:~to-15~
may be~blended with th2jlineax3biock~c~polymér component .- (.n-l.)~l~or~mayil~.be~ ùsedrf~excl~sively-,':~ 'as~ end ~use ,~ljconsiderations dictat~;?~ ~ Star~block~copolymers~are~useful 35-~ in:~t~he present~invention becau~e~of-~thelr ~upërio~r~ten~ile~
propertie~ and high, relatively flat, elastic mo~
.;; ~ The:-morphological. stru~ture~!of ;the resultant .
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"., W~90/1~662 .~ PCT/US90/0279~
t,~ 337 ~ 2i ,: , .
- , . 7 block copolymers is dependent on such factors as solvent, initiator, ratios of components, etc. Structures : including sphexes, ,cylinders, la~ellae, short rods and -~ rough networks are typically formed. See J. N. G. Cowie, '' S Development in Block_Copolymersl Applied Sciences, 18-35, :,, (1982)-P~eudo-block copolymer configurations of ~oft and hard homopolymer~-can also provide:the plateau region of ', the present,invention. Small, distinct regions of hard and soft homopolymers cross-linked together at' their boundaries with a suitable crosslinking agent, may provide similar performance to a block,.copolymer configuration.
~ The regions would typically bP 50-to 120 nm in the largest ; . dimension. Suitable crosslinXers include the azixidine . 15 crosslinking agents -described -in -U.S. Patent No.
.~., ,,, ~
-,,: 4,490,505, which,,is inicorporated herein by reference.' . . .
Examples~, of the vinyl substituted - aromatic ciompounds which may be u~ed as .monomers to produce the ho~opolymers -of segment A include styrene, 3-20. met~ylstyrene it 4-methylstyrene,--~: 4-ispropylstyrene, ;~-2--,~ eth~l-4-benzylstyrene, 4-p-tolystyrene, 4(4~phen'yl-n-b,utyl,)~ styre.ne~ 2~4-dimethylstyrener~ 5~ 4~,6-~;" trimeth~lstyrene, 3-methyl-5-n"-hexylstyrene, 'sulfonated tyxe~e, ,,l-vinylnaphthalene, ,.2-vinylnaphthalene, the 25 ~.alXyl, yycioalkylji~aryl,.alkaryl, and aralkyl'derivative~' ..o~vinylnaphthalene.and;the,.like.~lo~
- In addition to;cr.~inyl'~ ubstituted~ aroma'tic ~ompound~ ~ther e~amples of.'~,u~itabli3~,monomers'fiDr s'ëgment ~ .includi~s 'iL ac~ylonitriles,s~ Ci-C3(aI~l), Cl-C3 ;I 30~ alkyl)ac~y,la,,t,ies,c3(e.g-.. -~methyl methacrylate~,~f and~Svinyl jpyridines.~ 7,~ 0 -~1"J' f, ~ ~ r-~r,iS. ,.,P,,,r,~e,ferred,co,njugated dienes-for~usel'as'~mon'omers n~he~,soft segme,,nt{~ ~f;~th'e,.'present -in~ent'ion~a'rë?~'those .h~,a~ng,~rom~A.to,l2jcarbon ato~ k~Examples~of~suitable ~'; 1 35~0cnn~u~ate~d diene~,include l~3-butadiene~Ci~oprene~r~l~3~
p,e~nt~di~e,n,e fl(pip,,e,~y,"l,ene~ 2,3-dime'thyl-l~j3-butadienë,~ 3-~ butyl"lJ3-o,c,tadi,,,,e,,ne,,i ?:l-phenyl-l7~31 Lj butadiené~ ''?'l~,3-.. .
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~ WO90/14662 2~5~37 ~ PCT/US90/02792 . 8 :~
hexadiene, 1,3~octadiene~ 4 ethyl-1,3-hexadiene, l-chloro-1--3~butadiene, and the like. The use of a butadiene, isoprene or piperylene i5 preferred.
~ Examples of anionic polyfunctional coupling agents, component Y, that are~uitable or use -in the ; present invention include di~inyl benzene, silicon tetrachloride and ethylene dibromide.
:The pol~mers may be hydrogenated after:formation . o~ the block copolymer to.remov2 remaining unsaturation to prevent further crosslinking or oxidative cleavage.
Non-maqnetic Sup~ort :: `
~ The dispersion~ of binder material, magnetic pigment, and-addi~ives is coated onto a nonmàgnetic ~ .. support or base film....... Typical base -films include, -~ 15 polyethyleneterephthalatetpolyethylene-2-6-naphathalate, cellulose :acetate, cellulose triacetate, polyvinyl chloride, polyethylene, pol~propylene, :polycarbonate, polyamides, and others well kno~n in the art~- The~non-magnetic support film i5 coated on one or both sides:~ith 20- magnetic pigment dii3persed in the high molecular weight binder compound. :: The c~hickness- of'the:`base fiim is ,, ,typically~about.:3.. to.. ;100.micromêters,-and'preferabiy;about ? *.5 to~50 micrometers.s~
~ l.The support may have a:m~gnetic coating on:both sides of the support or:~the~ba~k-gide may be coated wlth-`~
a binder material containing carbon black or other static reducing non-magnetic:pigment.: l~.S.! :~, `. .;'. ' ,Maqlletic ~ Pi9111ent~and "AdditiVes ~3.i ~ ".;.?~ '} "J ~
~ The:,magnetic~pigment~that; is :utilized in~the ~ 30.~5present~invention~may~-~be any A~ma~netiC ~ pigme~nt~s~`uit~blé~for~
. the desired end u~e of the media. A preferrë~ma ~ ëkic .; plgmen~ _i9, ~, an.~.acicular :.ferromagnetic~~powdër having a !~ .,.. ,~length-of between.: bout:Ø1 and ~bou~ l.0 microns3and a ~ ra~io~of,length-;.and .~idth (ma~or3 a~is~~^lengt~lminor -'axis ¦ 3S~ length~ of~betw~en~.about~2 and~about-':20.~ ~^Examples~of~~
magnetic,~powder~ -~which~may:be'utllized in ~he~present I -in~ention include gamma'hemati~e (gamma-Fe203), magne ~ te , ., .. :
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~W~90/14662 PCT/US90/02792 3 ~5 ~;~t~ ~,t, ., ,,.. , . g (Fe304), mixed cryrstal of gamma -Fe203 and Fe204; cobalt-doped Fe203; cobalt doped Fe304; cobalt-doped mixed crystal of Fe2D3 and Fe304, chromium dioxide ( CrO2 ); various kinds of acicular magnetic alloy powders such as Ye Co, Co-Ni, Fe-Co-Ni, Fe-Co-B,- Fe-Co-Cr-B,^ Nn-Bi, Mn--Al, Fe-Co-V or ' ? the like; nitride of Fe, Fe-Co/ Fe-Co-Ni, fine iron, or the like; or mixtures of two or more of the above or other magnetic materials.
. In addition to the magnetic pigment various other additives can be added asj required. - For example, dispersing agents, lubricants, antioxidants, nonmagnetic pigments and other specific additives may be added to enhance the performa~ce of the-recording meclium.
.. Examples of lubricants include saturated and :15 unsaturated fatty acids, fatty acid esters, higher fatty :~acid amides, higher alcoholsj silicone oils, mineral oils, molybdenum disulfide, perfluoro ethers, and the like.--. ; . Examples of antioxidants which`may be used in the magnetic media of the present; invention include salicylanilide, tin oxide, mercury phenyloctoate, copper naphthenate,j zinc.; naphthenatle, :trichlorophenol, p-dinitrophenol, i sorbic - acid, :~butyl~ ~ p-oxybënzoate, dihydroacetoacetic.;acid and the~ e.~ --; J^-~ Dispersing agents servlP to-chèlate thè magnetic 25 partLcles and~ indi~iduallyt-suspended the`particles within-`~
~: i the uncured binder to-permit the~maximum-orientàtion'in ~- .3.the~destired tangential.direction-along-:tXe-imedia~surface ..a~er ~coating; the-: disperis~on-~f^?i-~magn`eti~p ~ nt.
; .jEffecti~e. ~dispersants ~.include-'~acrylatés, ~carboxylate 30 ~polyesters,~phosphate:3e~ters,~phospha~ë~ethers,~titanate r~coupiing; agents~ lecithin~ ;alkylsulfate, fatty 3 àcid .~JamiidesAi a~d~the-li~e~ ; L~ . 3 rJ ~ 5;~ '?.
on-ma~netic.pigments~wh`ich~mayi~be ~addéd-i-ai~ a r,~head;cleaning-agentror for:o~her purpo~es inciude ~ilicon 35 ;3 ,oxide;~-~ti~anium~.~.oxide;a aluminumoxide,-' ch~omium o~xide,~
calcium~carbonate-j' ~inc~oxide,~iand~Fè203-,- taicj Xà~ ln, -~rsilicon carbide~ carbo~lack and~th~eXiike. - ...t~iri , .~ .
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'~``' Formulation and Testinq of the Media The magnetic recording media of the -present invention can be made .by conventional techniques for making pigment/binder media. For example,' a dispersion is made by milling the ingredients :of the magnekizablé
layer te.g., binder,~,-gamma ferric oxide pigment, dispersant, solvent, lubricant, and carbon black) for a suf~icient time to obtain a uniform dispersion.` The ,jmilled .dispersion, is,--then..applied~in a:coating process, such as gravure or knife coating, to a flexible'support ~e.g., polyester film~. After coating, the coate~ backing or support material,,undergoes.orientation in''a magnetic field to align.the magnetizable particlesO ~he recording medium is then dried and cut into a desired size and shape -^~15 for end.use. . ~
.~. To produce:the. magnetic media'-of thé~ present "invention, it is,,preferred:.that the block copolymer be :~.dissolved in a single solvent such as toluene'to avoid the :~
precipitation of op,en.gel structures with imbi~ed'non-20, solvent during ,drying,::however,:, alternate -solvents or-solvent blends may be employed if the formulator'wishes to . ~ . ..
,~,3,jinfl,u,ence,,the po~l~m,er mo.rphology:of;;the final article.
i~ The fact,........... that no activation'::Aor :cure''steps: àre ,, required ..to.Sproduc,e .~the~ binder ~;composition for the 25; invent~ive .magnetic yme~ias allows,..ail'greatly -simpi'ified ,pro,duction proc,es,s~to be employed.t ::The-`reduction~in the number~,of ~binder,~,components;-Jxeduces the~oppbrtunity~or .j~,mi,schargesJ,and,3the1abse,np.e,o~ pot life const'ra`ints:~alI'ow~
.'the,,,dispersion,,to,b,ei3tested~or correct~-conipositio~i:p~lor ~,30~to coatin .iJ,.,,Ciean;3up~;of~the-~oating-rappara~us~has.bee --.,~L.found~to be~.J,~much~,~,eas,ier,l~han~-~'ith. 5~prior artr-Lbi'n.~er `,systems. Surface treater delays, oft`en:present in~us'ë'~'of Y' prio3~art binder~,~are~rminimiz0d.3L~s.?i~
r a 9~he blo,c,k,~,copo~ym~xs.-l-~of~the:ii.-pres-e'nt:~lnvé~'cion 35 ~,ha~,ei aJ.~umber of~h,em,~cal;~and ~echanical~propertiës~Yt~at'~
; make, them;e ~ eciallyl~ellJ~suitedYi for;usé~ri`n~i~ma'gn'e'tic media~ ~he~,hydroc,,a,rbon, backbone.oof~ the-;blnder of'the .
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~ W~90/1~662 ~ 37 PCT/~S90io2792 present invention is not subject to hydrolysis, a well known problem in the use of conventional urethane binders.
Also, performance variations due to h~midity are reduced because of the absence of polar groups in the binder composition. The phase separation which characterizès the ~`block pol~mers ~f the pre~ent in~ention provides a flat modulus vs. temperature profile, or plateau, between the Tgs of the constituent polymer blocks. The plateau extends beyond the environmental range normally required for magnetic media performance and may be raised or lowered to tailor the product for a particular end use by varying the ratio of the particular block copolymer compon~nts.
The molecular weights of the binders of the present invention are generally hîgh enough to ensure chain entanglements which, together with the high Tg of the hard block have been found to significantly reduce the problems associated with creep.
Formulations produced according to the present invention have shown excellent pigment wetting and dispersion stability. Magnetic performance has been at least equivalent to the use of con~entional binder ; materials. The binders accept high pigment loadings . ~, ... .
~ (above 80~ of the coating composition) without undue - degradation of the composite mechanical properties.
- 25 Typical coefficients of friction of media of the present invention have been about 0.2 without added lubricants, as compared to values of 0.3 and higher for conventional urethane binder systems. Alocking resistance has besn excellent. Especially with use of non-pl sticizing ~¦30 lubricants, media can be made having excellent durability.
This in~ention is further des~ribed and illustrated by the following non-limitin~ E~amples:
Examples 1 - 8 Magnetic media of ~he present invention were made by combining the ingredients in Table 1 as follows:
~ o a small shot mill, the pigment, the ~D 100 and the toluene were added and mixed briefly. Next the KR01 ,'' :..
:: . :, , , :, - . : ., ~WO90r14662 i; ~;:'" PCT/US9oio27g2 ~2050337 :~ 12 ~-and the carbon black, if.any, ~ere added and the mixture was milled for 30 minutes. The Kraton 1101 was added next and the mixture was milled fox.an additional 10 minutes.
The mixtures were then filtered and coated onto an unprifmed polyethylene.terepthalate backing with a 5 cm coater. The coatings were calendared and tested, giving .the results in ~able 2. .
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r,~ rj ¢ ~ ,r~3~~ ' ?~ 3 ~5 3 .1 .
Lr,. 2~ r ~ fj~;r ~ r: ,~jr~ c~
t~ f`X *~ r~J `~ .L ~ . -;tin; i ~ r,,q~ .ii -:~.~..' ~ .' ., ` .
..
' XIGH MOL~CULAR WEIGHT BINDERS ~OR
: , MAGNETIC RECORDING ~EDIA - - .
~"' 5 ' ''' ~ ' , ' , :
:.. `; The present in~ention relates to magnetic media 'and particularly to,~n Lmproved,magnetic media made from ,~,high molecular veight materials., :.: 10 Backqround of the Invention .,.. -., - ~ . . -;: ' The use of magnetizable particles ,affixed. to various substrates,to record, store, and reuse information ~`. con~inues to increase. The various forms of magne~izable ~, particles affixed to a substrate, often,termed magnetic ~,.. 15 medià, include, audio tapes,; video tapes,, computer : , diskettes, computer tapes, data.cartridges and many other `,' product~. In each of these constructions, magnetic particles are ~ound to a -substrate and,-information~is ': recorded ànd stored ,1;n.,the. magnetizable ~particles .for ~ . : ~ ... .....
. 20 later retrieval and use. , , . - , , '- ~ , : ~agnetic media must por?sess certain,physical and -.
,,; magnetic properties,to be su.itable for .-,use with the ,... ; various, magnetic reading.,and recording devices.;~ .Thesuraca of the media,must be suficiently~.,smooth r 80 ~ that ~' 25~ when read b,y the magnetic head,the recorded,signal.is,read`~. aecuràtely. ~perities or roughness in.the-media surface ~' can result in unaccept~ble ~levels.,of~.aignal, to~noise :~:. ratio. The media must also,be very durable.... -i~,It;~must~be ' able"to record and reproduce information repeatedly~
30 preferably ~housands,.i~not.~illions,of,;,,,time~. To be durable" the magnetic .~particl,eLs ,~must be,~-firmly~bound:3to~f;
$he sub&?txate;jand5;not,.,-be woJrn.~ff~,by.~the~.pa,ssing.,of~he '.'~ ma ~etic~ head~.,over.. the.~media. r~ ~In ~,addit~ion,1i-,it~is ~important that:the media have.sufficient~Llubricity,60~that '.''~35 the ma ~ etic.,jhead~passes .fr,,ee~ly~o~v,,er~the,~surfac.e:with a~
jm, ~i~n3~J~5, ",cit,~oef,"i~ci~eunt~o~f,,~f,~r~iAct,ion~ p.re,,f~erablyl~ithout~:the~~
neces6ity.~ f ~added~lubricanks.~ r~ nother~i portant charac~erls~tic ~o,~ a~m~agnet~c~m,edia~!is .that,~,,it.ihave very uniform phy~ical properties over a wide temperature range, .
,.:
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; . :1'." ,~,, ~ WO90/14662 2~503~j7! ~ PCT/US90/02792 ;' ` 2 such as a range of 100 C.
Typically, a magnetic- media is produced by passing a non-magnetic support through an apparatus which coats the support with a liquid dispersion of the magnetic layer. This di~persion consists of a binder, in either an uncured 'or solvated state',' ha~ing the~ magnetizable particles homogeneously dispèrsed therein. After coating, the dispersion dries or cures leaving a tough binder film having the magneti~able particleis unifo~mly distributed throughout.
- The ~esired physical and magnetic properties are often dictated by certain processing' parameters. One important parameter is good pigment wetting in the bulk - liquid dispersion.-- Good pigment wetting is closely '~
related to disperision stability and both are necessary to insurP evenly distributed pigment throughout the dispersion'and throughout the finished'magnetic coating.
Another important-processing parameter is the so-càlled pot life of the dispersion, t:he tLme for which the ~0 dispersion can be kept sufficiently non-viscous before coating. In general terms, a short pot-life, caused by a fast cure of the binder, creates time'constraints'in the ; coating proce'ss'"'and'problems in;obtaining'a suffic~entlysmooth surface~'bn-the magnetic layer. 'A longer pot-life often requires:a-slowèrlcur2 ratè,'oftèn'resulting in the :coated magnetic layer sùffering~damage as it is passed ;through the coating apparàtus in its insufficièntly~cured ! . .1 A-ma~ority ~f conve~tional mag~etic médiâ binders 30~are derive'd-rom lowër:'molécuîar we`ightimàtërials" ~ ich :~ilrequire'curing''~to~'~;gènera~e~ a3; binder -resin`''having the .Iappropriate:-physical prope~ies'.' In'à~dition to the po~-fe~considerati'ons~discu69ed above,'~the ùise of curable '3 low~ molëcular~ wëig~t ~s~rting materials cà~ càuse 35Yriadditional problëm~ TXe di'spërsion''of the'iow mo~ecular -;.weigh~ materi^als~may prëmaturely gei'or~'cause ~1Cculà~ion ¦ r~ of the magnetic particl~s5rësulting 'in non-ùni~o ~ and . ~
:.~ .
: ': ' . .. , .: ' ~.; WO90/14~2 PCT/US90~02792 337, . i; ~
( '' ' 3 unacceptable magnetic performance of the coatings. In addition, low molecular weight materials may remain in the binder after coating resulting in poor durability of'the magnetic coati~g. Further, low molecular w ight materials left aftPr cusing may migrate to the surface of the mediaj '-' and come into contact with the recording head where they can adversely affect performance through incxeased fxictionl stiction, head clogging, and/or poor blocking resistance.
Other problems encountered by magnetic 'media'-using conventional curable binder systems known in--the prior art include hydrolysis of the binder and degradation of the binder by humidity. In addition, the acti~ation or cure steps required by conventional-binder systems with , 15 curable lower molecular-,weight starting materials create additional complicated and expensive production steps.
,Known, polymerie -binder systems experie~cP a cha~ge - in physical properties over a range' of temperatures. In use, magnetic: media are often exposed to a wide range of te,mperatures, often over a range in excass of 100 C. ,The modulus oi' the binder mat*rial will typ.~ca,lly,,-j~substantially ichange over thi~ ra'nge, ' for ~"', ~ ,example;~from stiff and brittle ~o soft!'and tacky. These changes in physical ;properties can ;cause`'~rp'erformance 25i problems,in~the use of the media;- -~
In;view~of the above~deficiencies-~in-prior'art ; magnetic media binders, there is a need to -provide a binder suitable or use in'-magnetic ~media which is ' co~pri6ed of high molecuiar weigh`t start'ing' materials, 1 30 which do not require polymerization or,'~~crossli~king'to) $~form,~a~isuit~ble:m gneti'cu~coating.'-: In addition, it is dësirable that these hi~h molècular - weight'~binder materials~ provide-~ood:~ pigmenti'wett'ing a~d~ dispersion , ~tability, including systems with~3high'pigment~10a~ings.
~' 35 It i~ also desirable tha~ ~the ma'gnetic ~media ha~e -~-.,excellent,; mechanical~-properties','~r~uch æas'~moothness/
,~durability and--lubricity;,along with excellent~'electrical - , ~, .. .
, . : , .
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~ WO 90/1~62 PCT/US90/02792 , G ;~0 S0337~
properties, such as ~ignal-to-noi^~e ratio. It is al~o desirable that the physical and magnetic propertie~ of the media are relatively uniform throughout a wide range of temperatures. - - --, 5 ~Summary-of the Invsntion -~
; The present inventi~n there~ore- provides an improved magnetic recording :medium comprising a nonmagnetic support with at least one magnetic layer comprising a magnetizable pigment disper6ed~in-a binder composition. The binder composition of :the present inYention comprises a block copolymer, having a hard segment, with,~a gla58 ~ransition temperature (Tg) of greater than about 70 C, and a soft segment, having a Tg of less than about -30 C. ~:-", 15 The binder composition-of the present invention has relat~vely stable ph~sical properties over a range of temperaturesO A plot of the hog of the Modùlus (E'~ in dynes/cm2 ~ersus temperature in degre~s C, gives a plot having a plateau region. The absolute value of the average slope of!the plateau region,-S, is less than 8 X -~`. 10-3~ preferably;less-than~5 ~:10-3, and most preferably less~than 2 ,X, 10-3 ~ The:plateiau,region extends:o~ër a temperature range of at least 50 C, and praferably over a temperatur~,range of at,least lOO~C.~
~he binder compooiition of the present--invention-;
comprises~a block;copolymer~having the follo~ing general , j fo,rmula: 3; ,~'.,-;,~ ' `'.,`. 'i3'~5'.'~;-.-i~ ` `''`"-'`~' '~'-~ ''`~';' '`--'' B -:Y -~(B-~)~; C~J ., ~ f~ n_i'.Lr~b~ J~J~
wherein Y-is~aibsingle~bond or~a mùltifunc`~`ional ~-~ 30,~couplingiag~nt;t~ r -~I~LL~r?~ r~ r~
. A ~iS, a hard ~polymeric~segment ~having'ia~;iTg-Lof ~greater;*han about;-~70C; s~ r~ ?~ aPJ r ~
oi~ B,li a~oft~polymerie segment3hà~ing a ~8fof~1ëss ,han~ ~OUts~!30"C;,r~and,-~ J ,~7r; ~i&~ C~
- 35;~ n is~about 13~to 15-s~3 ~ir~r,r~ . o~ f~ 2 ,.c~,~,,,Glas~ltransition~ emperature.(Tg);isidefinè~-as the temperatuxe~at~which the polymerrchanges from a~"h~rd . .
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W090/14662 i~ 7 PCT/US9~/0~792 ~; . .
... , 5 brittle glassy material to a rubbery or viscous pol~ner.
Brief Description of the Draw~g~
Fi~. 1 is a plot of the Log E'.in dynes/cm2 versus Tempexature in C, for a binder material of the invention.
5Fig. 2 i~ a plot of.the ~og E' in dynes/cm2 versus Temperature in C, for a binder material of the present in~ention. : ~
~ Fig. 3 is a plot.of the hc33g E' in dynes/cm2 versus Tempera~ure in : C, for a comparative ex~nple of aiknown binder ma~erial. .-..`
Fig. 4 is a plot of the Log E' in dynes/cm2 versus Temperature in C, for a comparative example of a known binder material.
.. Detailed Description-of the I~vention . .
.. The present invention provides an improved :magnetic media that utilizes high molecular weight starting materials in a binder composition to secure the magnetizable pigment to a;non-magnetic support. The magnetic media of the present :invention i5 capable of ha~ing excellent electrical prope:rties, such as signal-to-:
.,.nois,e ratio.,,.In addition,.the properties.of the instan~
magnetîc media are very uniforrn over a wide range of temperat,ure6,~,typically.a range-lof~:at'..least 50 C, and ~ preferably~,-at,,least:~.100 C., ~h~3~,magnetic media'`'of-~jthe 25,~,pr~senti;,in,,vention;generally.comprise a ~inder 'material,~
magnetizable,-pigment, ,~and;.additives,:co~ted `on-`a~ non-magnetic suppor~
,, .~ ., ~,.. .
3Ij,.Binder,~ ,"-~ 5 -~ r ' '. 30 The bi~der 3composition ~ comprises.`i-ia~ block copolymer, hav.ing"a.,hard.segment~/~-A,'with7a-T8l~greater than ,a.,bJout"70_C,,andga~soft~,seyment, B; with a:Tg below-~about -~3~330 ,5.~ i~he molecular5,weight-.of the hard ~3egmen~ A,' is , r~pre,ferabl~3,~bout~,~10iOOO;:i~o;35,000,~.and the,softi'~egment, -~ 35,~;B,~preerably^has~a~molecularlweight~of:~about~ll5,'000 to ~ The hard-segment, A, is,:pre'ferably à homopolymer ,, ,. ,, :, ,. ,. , , , , - ... ... .. . . .
.WO~0/a4662 )~ PCT/US9o/0279i Z~ 337~
6 ...
comprised of a monovinyl aromatic monomer. Segment A will typically have a molecular weight of a~out 10,000 to lOO,OOO, and .preferably about~20,000 to 75,000. The monomer, molecular weight,~and polymferiza~ion process of the hard segment is selected such that the Tg of the hard segment A is greater than abou~ 70 C.
The soft segment, B, is preferably a homopolymar comprised of a conjugated diene!.monomer. Seyment B will typically have~a .molecular weight of about 10,-000 to 100,000, and preferably about 15,000 to 75,000. The monomer, molecular weight, and polymerization process off the soft segmfent, B, are selected such that the Tg is below ~bout -30 C. --:
- The-manufacture of block copolymers:is well-known in the art. For sxample, the homogenous A block may be grown as~ifollows~
~ .A* + A~ AA*
An AB block can be grown by adding B to an AA* cha`in as ~ollows: - -. AA* ~ B -> AB* --ThejAB~ chains.will frequently couple together to for~fABA
` ~ bl~ocks . ,i~ ,f ~ J~ r~ r;~ j 3 . .. ~ ii; ~...~f~
A .multifunctional coupling~iagent-can`~also` be added. :to .the.i .systefm to :formf--branched :~or ~ star . j25 r configurations.~ The~predominant~reaction:product ;of`the coupling reaction-resuIts-in~~a ~lock;copolymer-haY`ing the general formula~ e i;i p, '-- B -- Y ~ (B ~ ~n wherein Y is a single bond or a multifun`ctional 30~cc~oupling~agentj~cand n~.is^.about~l to7~15 .~~ ?The-star~iblock coPolymer eomponent (n:- 2:~to-15~
may be~blended with th2jlineax3biock~c~polymér component .- (.n-l.)~l~or~mayil~.be~ ùsedrf~excl~sively-,':~ 'as~ end ~use ,~ljconsiderations dictat~;?~ ~ Star~block~copolymers~are~useful 35-~ in:~t~he present~invention becau~e~of-~thelr ~upërio~r~ten~ile~
propertie~ and high, relatively flat, elastic mo~
.;; ~ The:-morphological. stru~ture~!of ;the resultant .
.
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"., W~90/1~662 .~ PCT/US90/0279~
t,~ 337 ~ 2i ,: , .
- , . 7 block copolymers is dependent on such factors as solvent, initiator, ratios of components, etc. Structures : including sphexes, ,cylinders, la~ellae, short rods and -~ rough networks are typically formed. See J. N. G. Cowie, '' S Development in Block_Copolymersl Applied Sciences, 18-35, :,, (1982)-P~eudo-block copolymer configurations of ~oft and hard homopolymer~-can also provide:the plateau region of ', the present,invention. Small, distinct regions of hard and soft homopolymers cross-linked together at' their boundaries with a suitable crosslinking agent, may provide similar performance to a block,.copolymer configuration.
~ The regions would typically bP 50-to 120 nm in the largest ; . dimension. Suitable crosslinXers include the azixidine . 15 crosslinking agents -described -in -U.S. Patent No.
.~., ,,, ~
-,,: 4,490,505, which,,is inicorporated herein by reference.' . . .
Examples~, of the vinyl substituted - aromatic ciompounds which may be u~ed as .monomers to produce the ho~opolymers -of segment A include styrene, 3-20. met~ylstyrene it 4-methylstyrene,--~: 4-ispropylstyrene, ;~-2--,~ eth~l-4-benzylstyrene, 4-p-tolystyrene, 4(4~phen'yl-n-b,utyl,)~ styre.ne~ 2~4-dimethylstyrener~ 5~ 4~,6-~;" trimeth~lstyrene, 3-methyl-5-n"-hexylstyrene, 'sulfonated tyxe~e, ,,l-vinylnaphthalene, ,.2-vinylnaphthalene, the 25 ~.alXyl, yycioalkylji~aryl,.alkaryl, and aralkyl'derivative~' ..o~vinylnaphthalene.and;the,.like.~lo~
- In addition to;cr.~inyl'~ ubstituted~ aroma'tic ~ompound~ ~ther e~amples of.'~,u~itabli3~,monomers'fiDr s'ëgment ~ .includi~s 'iL ac~ylonitriles,s~ Ci-C3(aI~l), Cl-C3 ;I 30~ alkyl)ac~y,la,,t,ies,c3(e.g-.. -~methyl methacrylate~,~f and~Svinyl jpyridines.~ 7,~ 0 -~1"J' f, ~ ~ r-~r,iS. ,.,P,,,r,~e,ferred,co,njugated dienes-for~usel'as'~mon'omers n~he~,soft segme,,nt{~ ~f;~th'e,.'present -in~ent'ion~a'rë?~'those .h~,a~ng,~rom~A.to,l2jcarbon ato~ k~Examples~of~suitable ~'; 1 35~0cnn~u~ate~d diene~,include l~3-butadiene~Ci~oprene~r~l~3~
p,e~nt~di~e,n,e fl(pip,,e,~y,"l,ene~ 2,3-dime'thyl-l~j3-butadienë,~ 3-~ butyl"lJ3-o,c,tadi,,,,e,,ne,,i ?:l-phenyl-l7~31 Lj butadiené~ ''?'l~,3-.. .
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~ WO90/14662 2~5~37 ~ PCT/US90/02792 . 8 :~
hexadiene, 1,3~octadiene~ 4 ethyl-1,3-hexadiene, l-chloro-1--3~butadiene, and the like. The use of a butadiene, isoprene or piperylene i5 preferred.
~ Examples of anionic polyfunctional coupling agents, component Y, that are~uitable or use -in the ; present invention include di~inyl benzene, silicon tetrachloride and ethylene dibromide.
:The pol~mers may be hydrogenated after:formation . o~ the block copolymer to.remov2 remaining unsaturation to prevent further crosslinking or oxidative cleavage.
Non-maqnetic Sup~ort :: `
~ The dispersion~ of binder material, magnetic pigment, and-addi~ives is coated onto a nonmàgnetic ~ .. support or base film....... Typical base -films include, -~ 15 polyethyleneterephthalatetpolyethylene-2-6-naphathalate, cellulose :acetate, cellulose triacetate, polyvinyl chloride, polyethylene, pol~propylene, :polycarbonate, polyamides, and others well kno~n in the art~- The~non-magnetic support film i5 coated on one or both sides:~ith 20- magnetic pigment dii3persed in the high molecular weight binder compound. :: The c~hickness- of'the:`base fiim is ,, ,typically~about.:3.. to.. ;100.micromêters,-and'preferabiy;about ? *.5 to~50 micrometers.s~
~ l.The support may have a:m~gnetic coating on:both sides of the support or:~the~ba~k-gide may be coated wlth-`~
a binder material containing carbon black or other static reducing non-magnetic:pigment.: l~.S.! :~, `. .;'. ' ,Maqlletic ~ Pi9111ent~and "AdditiVes ~3.i ~ ".;.?~ '} "J ~
~ The:,magnetic~pigment~that; is :utilized in~the ~ 30.~5present~invention~may~-~be any A~ma~netiC ~ pigme~nt~s~`uit~blé~for~
. the desired end u~e of the media. A preferrë~ma ~ ëkic .; plgmen~ _i9, ~, an.~.acicular :.ferromagnetic~~powdër having a !~ .,.. ,~length-of between.: bout:Ø1 and ~bou~ l.0 microns3and a ~ ra~io~of,length-;.and .~idth (ma~or3 a~is~~^lengt~lminor -'axis ¦ 3S~ length~ of~betw~en~.about~2 and~about-':20.~ ~^Examples~of~~
magnetic,~powder~ -~which~may:be'utllized in ~he~present I -in~ention include gamma'hemati~e (gamma-Fe203), magne ~ te , ., .. :
,,, , : . :
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. . ., : , ,: . . , : .:
.. .
~W~90/14662 PCT/US90/02792 3 ~5 ~;~t~ ~,t, ., ,,.. , . g (Fe304), mixed cryrstal of gamma -Fe203 and Fe204; cobalt-doped Fe203; cobalt doped Fe304; cobalt-doped mixed crystal of Fe2D3 and Fe304, chromium dioxide ( CrO2 ); various kinds of acicular magnetic alloy powders such as Ye Co, Co-Ni, Fe-Co-Ni, Fe-Co-B,- Fe-Co-Cr-B,^ Nn-Bi, Mn--Al, Fe-Co-V or ' ? the like; nitride of Fe, Fe-Co/ Fe-Co-Ni, fine iron, or the like; or mixtures of two or more of the above or other magnetic materials.
. In addition to the magnetic pigment various other additives can be added asj required. - For example, dispersing agents, lubricants, antioxidants, nonmagnetic pigments and other specific additives may be added to enhance the performa~ce of the-recording meclium.
.. Examples of lubricants include saturated and :15 unsaturated fatty acids, fatty acid esters, higher fatty :~acid amides, higher alcoholsj silicone oils, mineral oils, molybdenum disulfide, perfluoro ethers, and the like.--. ; . Examples of antioxidants which`may be used in the magnetic media of the present; invention include salicylanilide, tin oxide, mercury phenyloctoate, copper naphthenate,j zinc.; naphthenatle, :trichlorophenol, p-dinitrophenol, i sorbic - acid, :~butyl~ ~ p-oxybënzoate, dihydroacetoacetic.;acid and the~ e.~ --; J^-~ Dispersing agents servlP to-chèlate thè magnetic 25 partLcles and~ indi~iduallyt-suspended the`particles within-`~
~: i the uncured binder to-permit the~maximum-orientàtion'in ~- .3.the~destired tangential.direction-along-:tXe-imedia~surface ..a~er ~coating; the-: disperis~on-~f^?i-~magn`eti~p ~ nt.
; .jEffecti~e. ~dispersants ~.include-'~acrylatés, ~carboxylate 30 ~polyesters,~phosphate:3e~ters,~phospha~ë~ethers,~titanate r~coupiing; agents~ lecithin~ ;alkylsulfate, fatty 3 àcid .~JamiidesAi a~d~the-li~e~ ; L~ . 3 rJ ~ 5;~ '?.
on-ma~netic.pigments~wh`ich~mayi~be ~addéd-i-ai~ a r,~head;cleaning-agentror for:o~her purpo~es inciude ~ilicon 35 ;3 ,oxide;~-~ti~anium~.~.oxide;a aluminumoxide,-' ch~omium o~xide,~
calcium~carbonate-j' ~inc~oxide,~iand~Fè203-,- taicj Xà~ ln, -~rsilicon carbide~ carbo~lack and~th~eXiike. - ...t~iri , .~ .
-.. . ..
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WOsO/14~62 ' P~T/US9oio27g2 f ~
'~``' Formulation and Testinq of the Media The magnetic recording media of the -present invention can be made .by conventional techniques for making pigment/binder media. For example,' a dispersion is made by milling the ingredients :of the magnekizablé
layer te.g., binder,~,-gamma ferric oxide pigment, dispersant, solvent, lubricant, and carbon black) for a suf~icient time to obtain a uniform dispersion.` The ,jmilled .dispersion, is,--then..applied~in a:coating process, such as gravure or knife coating, to a flexible'support ~e.g., polyester film~. After coating, the coate~ backing or support material,,undergoes.orientation in''a magnetic field to align.the magnetizable particlesO ~he recording medium is then dried and cut into a desired size and shape -^~15 for end.use. . ~
.~. To produce:the. magnetic media'-of thé~ present "invention, it is,,preferred:.that the block copolymer be :~.dissolved in a single solvent such as toluene'to avoid the :~
precipitation of op,en.gel structures with imbi~ed'non-20, solvent during ,drying,::however,:, alternate -solvents or-solvent blends may be employed if the formulator'wishes to . ~ . ..
,~,3,jinfl,u,ence,,the po~l~m,er mo.rphology:of;;the final article.
i~ The fact,........... that no activation'::Aor :cure''steps: àre ,, required ..to.Sproduc,e .~the~ binder ~;composition for the 25; invent~ive .magnetic yme~ias allows,..ail'greatly -simpi'ified ,pro,duction proc,es,s~to be employed.t ::The-`reduction~in the number~,of ~binder,~,components;-Jxeduces the~oppbrtunity~or .j~,mi,schargesJ,and,3the1abse,np.e,o~ pot life const'ra`ints:~alI'ow~
.'the,,,dispersion,,to,b,ei3tested~or correct~-conipositio~i:p~lor ~,30~to coatin .iJ,.,,Ciean;3up~;of~the-~oating-rappara~us~has.bee --.,~L.found~to be~.J,~much~,~,eas,ier,l~han~-~'ith. 5~prior artr-Lbi'n.~er `,systems. Surface treater delays, oft`en:present in~us'ë'~'of Y' prio3~art binder~,~are~rminimiz0d.3L~s.?i~
r a 9~he blo,c,k,~,copo~ym~xs.-l-~of~the:ii.-pres-e'nt:~lnvé~'cion 35 ~,ha~,ei aJ.~umber of~h,em,~cal;~and ~echanical~propertiës~Yt~at'~
; make, them;e ~ eciallyl~ellJ~suitedYi for;usé~ri`n~i~ma'gn'e'tic media~ ~he~,hydroc,,a,rbon, backbone.oof~ the-;blnder of'the .
: -,.
~i ,i ;, ~ ,,. .;-., ,~. . . .,.:
. : .: , . . ,: :
~ W~90/1~662 ~ 37 PCT/~S90io2792 present invention is not subject to hydrolysis, a well known problem in the use of conventional urethane binders.
Also, performance variations due to h~midity are reduced because of the absence of polar groups in the binder composition. The phase separation which characterizès the ~`block pol~mers ~f the pre~ent in~ention provides a flat modulus vs. temperature profile, or plateau, between the Tgs of the constituent polymer blocks. The plateau extends beyond the environmental range normally required for magnetic media performance and may be raised or lowered to tailor the product for a particular end use by varying the ratio of the particular block copolymer compon~nts.
The molecular weights of the binders of the present invention are generally hîgh enough to ensure chain entanglements which, together with the high Tg of the hard block have been found to significantly reduce the problems associated with creep.
Formulations produced according to the present invention have shown excellent pigment wetting and dispersion stability. Magnetic performance has been at least equivalent to the use of con~entional binder ; materials. The binders accept high pigment loadings . ~, ... .
~ (above 80~ of the coating composition) without undue - degradation of the composite mechanical properties.
- 25 Typical coefficients of friction of media of the present invention have been about 0.2 without added lubricants, as compared to values of 0.3 and higher for conventional urethane binder systems. Alocking resistance has besn excellent. Especially with use of non-pl sticizing ~¦30 lubricants, media can be made having excellent durability.
This in~ention is further des~ribed and illustrated by the following non-limitin~ E~amples:
Examples 1 - 8 Magnetic media of ~he present invention were made by combining the ingredients in Table 1 as follows:
~ o a small shot mill, the pigment, the ~D 100 and the toluene were added and mixed briefly. Next the KR01 ,'' :..
:: . :, , , :, - . : ., ~WO90r14662 i; ~;:'" PCT/US9oio27g2 ~2050337 :~ 12 ~-and the carbon black, if.any, ~ere added and the mixture was milled for 30 minutes. The Kraton 1101 was added next and the mixture was milled fox.an additional 10 minutes.
The mixtures were then filtered and coated onto an unprifmed polyethylene.terepthalate backing with a 5 cm coater. The coatings were calendared and tested, giving .the results in ~able 2. .
. ~, - , .. ; .. . .. .. , . -,,. . ; f. ~
.
,., . - . . , ~:
: - - .: :
~ . . . .
. ~¦ f;~Cf. ~ c~ r,~ f ~C~ JS~J':"i'-~
Jf~i ~r.';-~.~:r'i ^5'.~;3 T.r~ .f 3~ 3~ - ~;~
'~ h ~* ~ r ~r. .;
r,~ rj ¢ ~ ,r~3~~ ' ?~ 3 ~5 3 .1 .
Lr,. 2~ r ~ fj~;r ~ r: ,~jr~ c~
t~ f`X *~ r~J `~ .L ~ . -;tin; i ~ r,,q~ .ii -:~.~..' ~ .' ., ` .
..
'; ;~ 6~15 ![3; 3 3~7 Table 1 _____ Example 1 _ _2 _3 4 5 6 7_ 8 Component~ Nei~ht_in Grams S KROll 19.~.25.5 2~.7 26.7 ~4.0 18.0 14.7 18.9 Kraton 1101~ 8.5 2.8 8.9 2.9 6.0 ~.0 S.3 2.1 Carbon Black ~ 1.2 1.2 -~ 1.2 Toluene 38.5 38.5 43.5 43.5 38.5 38.5 43.5 43.5 Pigment3 30 30 30 30 30 30 30 30 WAPHOS-TD
1004 l.S 1.51.5 1.5 1.5 1.5 1.5 1.5 ~' ~
~ROl is a ."K-Resin", Butadiene/styrene (BDS) polymer from Phillips Chemical.Co. The styrene block . has a 12,000 M.~., butadiene block has a 28,000 NoW~
with 65% styrene and 35% butadiene in a star polymer configuration, with predominantly 3 arms, but some 4 ~ and 6 arms.
`; 2 ~ Kraton 1101 is a ABA styrene/butadiene/s~yrene copolymer.from Shell; 30% styrene, 70~ butadiene.
1004 l.S 1.51.5 1.5 1.5 1.5 1.5 1.5 ~' ~
~ROl is a ."K-Resin", Butadiene/styrene (BDS) polymer from Phillips Chemical.Co. The styrene block . has a 12,000 M.~., butadiene block has a 28,000 NoW~
with 65% styrene and 35% butadiene in a star polymer configuration, with predominantly 3 arms, but some 4 ~ and 6 arms.
`; 2 ~ Kraton 1101 is a ABA styrene/butadiene/s~yrene copolymer.from Shell; 30% styrene, 70~ butadiene.
3, `: ~ _ An acicular gammà-iron oxi~e'' `~
' 4 i ~ Obtained from the~Philip A. s~unt Chemical Corp., :: 35 Organic.Di~.,:-P.O. -~ox`4249, ~assasoitiA~e., East Providence, RI 02~14 ;
`'~1 ` ~1 I
.
. 1 .
.
i .;
.~ .. ~
: .-; :; :, , ,, .: " , - , . .:
,- : .: ., ~ ....... ~ . .: . : :::
.. ~: . . . ..
. . :i~; ~ . :: :
". . . : : ~ . . .: : .
.. ::
. ..
... ..
h A ,~ , ", ~. ~
2,~ ,33~ 14 Table 2 D . L . Coef .
Exa3 ple Wear Friction ~r Squareness Hc Br 19 . 9 0 . 22 ~~6~5 0 . 776 3~7 1233 243 . 0 0 . 3 - - - 659 C3 . 725 327 1256 315 . 5 0 . 27 ~ 524 0 . 759 325 1098 10 , ' ' ` ' ' 4 33.5 0.23 553 0.7~7 327 1127 `51~3.9 0.2 ;- 5533 0.781 311 13~37 .
632 . 8 - 0 . 23 688 0 . 780 310 13i3 7 3O7 0.2,3 498 0.761 311 1252 8 22.5 0 .22 591 0 0 761 311 1239 Examples 9 - 12 ~. . Nagnetic media of~the present i.nvention were made 25 by - combining the ingredients as set forth in Table 3. TG3 a small shotmill;-~the..piyment, dispersing agent, and .. .. . ... . .... .. . .
-solvent were àdded and mixed briefly. .Next, the binder polymer present as 36%i solid~ in cyclohexanone was added . along.with;thé.lubricant-and.the mixture was milled for 30 .. ~O~minutes. The mi~ture was~filt2redl, de.aeratediand coated on a PE~r backing using a knife cc)ater. The coating was . ~calend re;d~and~t,e~ted.. ~~ The test.~results-.are reported in .~ 35 !
.~
~,i . .
, , ~ ';I - .
i~ , .
,~ ' .
, . -... .
~i .
, ~ . .... ..... ... . .... .. ..
, i .,, ... .. ". .... .. ..
.. .... ... .. .... ..
. WO 90/14~62 PCI/llS9~/OZ7~
i63337 ;; j~;
Table 3 Example 9 10 11 -~12 Components Wt. in qrams Binder Al2 3 ~ 8 ` .2 3 . 8 -16 . 216 . 2 4GOD~2 0 . 6 -- O . 5 --Oleic acid3 -- 0.6 -- 0.5 Pigment" 30 30 30 30 Emcol Acetate5 1.2 1.2 1.2 1.2 Cyclohexanone 42 . 6 42 . 6 44 . 3 44 . 3 ~ Binder ~ (36% solids in cyclohexanone) was an ABAI styrene/Butadinetstyrene block with styrene blocks--52,000 MW and butadiene Blocks--88,000 ~$W.
;~ The polymer was 90% coupled.
2 Lubricant - polyethylene glycol dilaurate - M.W.
400 commercially available :Erom Hodag.
3 Lubrican~, i ` 4 , An acicular gamma iron oxide.
:~ ~5 Dispersing agent - co~mercially available from Witco Chemical Corp., 277 Park Ave., New York, NY
Table 4 Coef.
Example Friction c~Squareness ~ B
-- _z _c _r 9 0.25 5490.819 284 1644 1() 0 . 2 6d,90 ~ 806 ~284 1774 11 0.25 7360.80 27B 1780 12 002 7590.796 279 1830 Examples 131 14L A and B
A comparatiYe magnetic m~dium (E~ample ~) was prepared by mi~ing 7 parts Emcol Acetate, VROH vinyl binder ,. i WO~'0/14662 PCT/~S90/02792 resin from Union Carbide, in a 1:1 mixture of toluene and methyl ethyl ketone to give a 70% grinds solids mixture.
.100 paxts of a magnetic pigment was also mixed in;- The mixture was milled for 25 minutes with a 15 minute thin 5 down using NEK solvent. The final percent solids wàs-^48~
'The Example 13 medium was made in a similar manner except the binder was Binder A and the thin-down solvent was ~:toluene. Comparative Example B was prepared by mixing-7%
by weight of the pigment TD100, r~ an Estane 5707 binder 10 (BFG), and a fine particulate iron pigment at 80~-grind solids and a 4il ratio of pigment to binder polymer.
Toluene was u~ed as a mill solvent. Nilling was for- 45 minutes with a 15 minute thin-down. The final percent :solids was 50%.: Example 14 was made in~ a similar manner .,15 except the~binder was Binder A. The test results are set .foxth in-Table 5.
.~ .
`~Table 5 Example S~uareness Hc Br ~
13 0.800 639 1560 2.5 : A 0.848 660-- 1330 :~ 2~8 14 0.749 940 3510 2.24 .. 1 B 0.801;. ~ .. 940--~ ``3920 2.61 " . .
'~ L ~
,d~J -~ - t ~r~ I
8 r ~ ;~ d ~ j .1. c-_ :1 ~ r~ r ~ J.,"~ r . . ~ .- t - i ` ~ ~ ~5 ~, 7, `~ .-.r~ r.~ L.. ~ E~- , ._ .~, !_.. _ _ ''1 , . . .
'' . ' , ;' . ~ ' , ,' ''. ., ,. , : ' . `' . . .,.:. ' ' ~ ' ,' :,
' 4 i ~ Obtained from the~Philip A. s~unt Chemical Corp., :: 35 Organic.Di~.,:-P.O. -~ox`4249, ~assasoitiA~e., East Providence, RI 02~14 ;
`'~1 ` ~1 I
.
. 1 .
.
i .;
.~ .. ~
: .-; :; :, , ,, .: " , - , . .:
,- : .: ., ~ ....... ~ . .: . : :::
.. ~: . . . ..
. . :i~; ~ . :: :
". . . : : ~ . . .: : .
.. ::
. ..
... ..
h A ,~ , ", ~. ~
2,~ ,33~ 14 Table 2 D . L . Coef .
Exa3 ple Wear Friction ~r Squareness Hc Br 19 . 9 0 . 22 ~~6~5 0 . 776 3~7 1233 243 . 0 0 . 3 - - - 659 C3 . 725 327 1256 315 . 5 0 . 27 ~ 524 0 . 759 325 1098 10 , ' ' ` ' ' 4 33.5 0.23 553 0.7~7 327 1127 `51~3.9 0.2 ;- 5533 0.781 311 13~37 .
632 . 8 - 0 . 23 688 0 . 780 310 13i3 7 3O7 0.2,3 498 0.761 311 1252 8 22.5 0 .22 591 0 0 761 311 1239 Examples 9 - 12 ~. . Nagnetic media of~the present i.nvention were made 25 by - combining the ingredients as set forth in Table 3. TG3 a small shotmill;-~the..piyment, dispersing agent, and .. .. . ... . .... .. . .
-solvent were àdded and mixed briefly. .Next, the binder polymer present as 36%i solid~ in cyclohexanone was added . along.with;thé.lubricant-and.the mixture was milled for 30 .. ~O~minutes. The mi~ture was~filt2redl, de.aeratediand coated on a PE~r backing using a knife cc)ater. The coating was . ~calend re;d~and~t,e~ted.. ~~ The test.~results-.are reported in .~ 35 !
.~
~,i . .
, , ~ ';I - .
i~ , .
,~ ' .
, . -... .
~i .
, ~ . .... ..... ... . .... .. ..
, i .,, ... .. ". .... .. ..
.. .... ... .. .... ..
. WO 90/14~62 PCI/llS9~/OZ7~
i63337 ;; j~;
Table 3 Example 9 10 11 -~12 Components Wt. in qrams Binder Al2 3 ~ 8 ` .2 3 . 8 -16 . 216 . 2 4GOD~2 0 . 6 -- O . 5 --Oleic acid3 -- 0.6 -- 0.5 Pigment" 30 30 30 30 Emcol Acetate5 1.2 1.2 1.2 1.2 Cyclohexanone 42 . 6 42 . 6 44 . 3 44 . 3 ~ Binder ~ (36% solids in cyclohexanone) was an ABAI styrene/Butadinetstyrene block with styrene blocks--52,000 MW and butadiene Blocks--88,000 ~$W.
;~ The polymer was 90% coupled.
2 Lubricant - polyethylene glycol dilaurate - M.W.
400 commercially available :Erom Hodag.
3 Lubrican~, i ` 4 , An acicular gamma iron oxide.
:~ ~5 Dispersing agent - co~mercially available from Witco Chemical Corp., 277 Park Ave., New York, NY
Table 4 Coef.
Example Friction c~Squareness ~ B
-- _z _c _r 9 0.25 5490.819 284 1644 1() 0 . 2 6d,90 ~ 806 ~284 1774 11 0.25 7360.80 27B 1780 12 002 7590.796 279 1830 Examples 131 14L A and B
A comparatiYe magnetic m~dium (E~ample ~) was prepared by mi~ing 7 parts Emcol Acetate, VROH vinyl binder ,. i WO~'0/14662 PCT/~S90/02792 resin from Union Carbide, in a 1:1 mixture of toluene and methyl ethyl ketone to give a 70% grinds solids mixture.
.100 paxts of a magnetic pigment was also mixed in;- The mixture was milled for 25 minutes with a 15 minute thin 5 down using NEK solvent. The final percent solids wàs-^48~
'The Example 13 medium was made in a similar manner except the binder was Binder A and the thin-down solvent was ~:toluene. Comparative Example B was prepared by mixing-7%
by weight of the pigment TD100, r~ an Estane 5707 binder 10 (BFG), and a fine particulate iron pigment at 80~-grind solids and a 4il ratio of pigment to binder polymer.
Toluene was u~ed as a mill solvent. Nilling was for- 45 minutes with a 15 minute thin-down. The final percent :solids was 50%.: Example 14 was made in~ a similar manner .,15 except the~binder was Binder A. The test results are set .foxth in-Table 5.
.~ .
`~Table 5 Example S~uareness Hc Br ~
13 0.800 639 1560 2.5 : A 0.848 660-- 1330 :~ 2~8 14 0.749 940 3510 2.24 .. 1 B 0.801;. ~ .. 940--~ ``3920 2.61 " . .
'~ L ~
,d~J -~ - t ~r~ I
8 r ~ ;~ d ~ j .1. c-_ :1 ~ r~ r ~ J.,"~ r . . ~ .- t - i ` ~ ~ ~5 ~, 7, `~ .-.r~ r.~ L.. ~ E~- , ._ .~, !_.. _ _ ''1 , . . .
'' . ' , ;' . ~ ' , ,' ''. ., ,. , : ' . `' . . .,.:. ' ' ~ ' ,' :,
Claims (18)
1. A magnetic recording medium having a magnetizable coating, said magnetizable coating comprising a magnetizable pigment dispersed in a binder-composition comprising a block copolymer having the following general formula:
A-B-Y-(B-A)u;
wherein Y is a single bond or a multifunctional coupling agent;
n is 1 to 15;
A is a hard polymeric segment having a Tg of greater than about 70 C; and B is a soft polymeric segment having a Tg of less than about -30 C; said binder composition having an S value of less than 8 x 10-3 over a temperature range of about 50°C.
A-B-Y-(B-A)u;
wherein Y is a single bond or a multifunctional coupling agent;
n is 1 to 15;
A is a hard polymeric segment having a Tg of greater than about 70 C; and B is a soft polymeric segment having a Tg of less than about -30 C; said binder composition having an S value of less than 8 x 10-3 over a temperature range of about 50°C.
2. The recording medium of claim 1 wherein said binder composition has an S value of less than 8 X 10-3 over a temperature range of about 100°C.
3. The recording medium of claim 1 wherein said binder composition has an S value of less than 5 X 10-3.
4. The recording medium of claim 3 wherein said binder composition has an S value of less than 2 X 10-3.
5. The recording medium of claim 1 wherein segment A has a molecular weight of about 10,000 to 70,000 and segment B has a molecular weight of about 15,000 to 75,000.
6. The recording medium of claim 5, wherein segment A is a homopolymer comprising a monovinyl aromatic monomer.
7. The recording medium of claim 6, wherein said monovinyl aromatic monomer has about 8-18 carbon atoms.
8. The recording medium of claim 7, wherein said monovinyl aromatic monomer is selected from the group consisting of styrene, hydrogenated and partially hydrogenated styrene, and alkylated styrenes.
9. The recording medium of claim 5 wherein segment B is a homopolymer comprising a conjugated diene monomer.
10. The recording medium of claim 9 wherein said conjugated diene monomer has about 4-12 carbon atoms.
11. The recording medium of claim 9 wherein said conjugated diene monomer is selected from the group consisting of butadiene, isoprene, piperylene, and hydrogenated or partially hydrogenated butadiene, isoprene, and piperylene.
12. A magnetic recording medium having a magnetizable coating, said magnetizable coating comprising a magnetizable pigment dispersed in a binder composition having a S value of less than 8 x 10-3 over a temperature range of about 50°C, said composition comprising:
(a) about 30 to 90 percent by weight of a block copolymer having the general formula A-B-B-A; and (ii) about 10 to 70 percent by weight of a starblock copolymer having the general formula:
A-B-Y(B-A)n wherein A is a hard polymeric segment having a molecular weight of about 10,000 to 70,000, and a Tg of greater than about 70°C;
B is a soft polymeric segment having a molecular weight of about 15,000 to 70,000 and a Tg of below about -30°C;
n is an integer of about 2 to 15; and Y is a multi-functional coupling agent.
(a) about 30 to 90 percent by weight of a block copolymer having the general formula A-B-B-A; and (ii) about 10 to 70 percent by weight of a starblock copolymer having the general formula:
A-B-Y(B-A)n wherein A is a hard polymeric segment having a molecular weight of about 10,000 to 70,000, and a Tg of greater than about 70°C;
B is a soft polymeric segment having a molecular weight of about 15,000 to 70,000 and a Tg of below about -30°C;
n is an integer of about 2 to 15; and Y is a multi-functional coupling agent.
13. The recording medium of claim 12 wherein said segment A is comprised of a monovinyl aromatic monomer having about 8-18 carbon atoms and segment B is comprised of a conjugated diene monomer having about 4-12 carbon atoms.
14. The recording medium of claim 12 wherein binder composition an S has value of less than 8 X 10-3 over a temperature range of about 100°C.
15. The recording medium of claim 14, wherein said binder composition has an S value of less than 5 X 10-3.
16. The recording medium of claim 15 wherein said binder composition has an S value of less than 2 X 10-3.
17. The recording medium of claim 13 wherein said monovinyl aromatic monomer is selected from the group consisting of styrene, hydrogenated or partially hydrogenated styrene, and alkylated styrenes.
18. The recording medium of claim 13, wherein said conjugated diene monomer is selected from the group consisting of butadiene, isoprene and piperylene, and hydrogenated or partially hydrogenated butadiene, isoprene, and piperylene.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US353,978 | 1989-05-19 | ||
| US07/353,978 US5128215A (en) | 1989-05-19 | 1989-05-19 | Magnetic recording media binder resin comprising a mixture of a straight block copolymer and a star block copolymer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2050337A1 true CA2050337A1 (en) | 1990-11-20 |
Family
ID=23391400
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002050337A Abandoned CA2050337A1 (en) | 1989-05-19 | 1990-05-21 | High molecular weight binders for magnetic recording media |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5128215A (en) |
| EP (1) | EP0472640B1 (en) |
| JP (1) | JPH04505381A (en) |
| KR (1) | KR920701943A (en) |
| CA (1) | CA2050337A1 (en) |
| DE (1) | DE69021209T2 (en) |
| WO (1) | WO1990014662A1 (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03201508A (en) * | 1989-12-28 | 1991-09-03 | Sankyo Seiki Mfg Co Ltd | Manufacture of resin-bonded magnet |
| US5487951A (en) * | 1991-07-08 | 1996-01-30 | Minnesota Mining And Manufacturing Company | Magnetic recording medium with a binder resin of a starblock copolymer having at least six arms |
| GB9114668D0 (en) * | 1991-07-08 | 1991-08-28 | Minnesota Mining & Mfg | Magnetic recording materials |
| US5769996A (en) * | 1994-01-27 | 1998-06-23 | Loctite (Ireland) Limited | Compositions and methods for providing anisotropic conductive pathways and bonds between two sets of conductors |
| US5480695A (en) * | 1994-08-10 | 1996-01-02 | Tenhover; Michael A. | Ceramic substrates and magnetic data storage components prepared therefrom |
| US5851644A (en) * | 1995-08-01 | 1998-12-22 | Loctite (Ireland) Limited | Films and coatings having anisotropic conductive pathways therein |
| GB2307872A (en) * | 1995-12-04 | 1997-06-11 | Minnesota Mining & Mfg | Star polymer binder for magnetic recording materials |
| US6977025B2 (en) * | 1996-08-01 | 2005-12-20 | Loctite (R&D) Limited | Method of forming a monolayer of particles having at least two different sizes, and products formed thereby |
| BR9706597A (en) | 1996-08-01 | 1999-07-20 | Loctite Ireland Ltd | Process for forming a monolayer of particles and products formed in this way |
| US5916641A (en) * | 1996-08-01 | 1999-06-29 | Loctite (Ireland) Limited | Method of forming a monolayer of particles |
| US6402876B1 (en) | 1997-08-01 | 2002-06-11 | Loctite (R&D) Ireland | Method of forming a monolayer of particles, and products formed thereby |
| US10773093B2 (en) * | 2017-05-29 | 2020-09-15 | Elegant Mathematics LLC | Real-time methods for magnetic resonance spectra acquisition, imaging and non-invasive ablation |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1260132B (en) * | 1966-07-27 | 1968-02-01 | Basf Ag | Process for the production of magnetogram carriers |
| US4490505A (en) * | 1980-04-17 | 1984-12-25 | Minnesota Mining And Manufacturing Company | Polyfunctional aziridine crosslinking agents for aqueous magnetic recording media binder |
| US4426495A (en) * | 1981-07-13 | 1984-01-17 | The General Tire & Rubber Company | Preparation of star polymers |
| US4412941A (en) * | 1981-10-22 | 1983-11-01 | Phillips Petroleum Company | Recording disc compositions comprising polymers of monovinyl-substituted hydrocarbons, conductive carbon black and lubricants |
| JPS59129266A (en) * | 1983-01-12 | 1984-07-25 | Toagosei Chem Ind Co Ltd | Magnetic coating |
| JPS59129267A (en) * | 1983-01-14 | 1984-07-25 | Toagosei Chem Ind Co Ltd | Ionizing radiation-curing magnetic coating |
| JPS59196340A (en) * | 1983-04-21 | 1984-11-07 | Kanegafuchi Chem Ind Co Ltd | Thermoplastic elastomer composition containing magnetic material |
-
1989
- 1989-05-19 US US07/353,978 patent/US5128215A/en not_active Expired - Fee Related
-
1990
- 1990-05-21 JP JP2508258A patent/JPH04505381A/en active Pending
- 1990-05-21 DE DE69021209T patent/DE69021209T2/en not_active Expired - Fee Related
- 1990-05-21 KR KR1019910701617A patent/KR920701943A/en active IP Right Grant
- 1990-05-21 CA CA002050337A patent/CA2050337A1/en not_active Abandoned
- 1990-05-21 EP EP90908778A patent/EP0472640B1/en not_active Expired - Lifetime
- 1990-05-21 WO PCT/US1990/002792 patent/WO1990014662A1/en active IP Right Grant
Also Published As
| Publication number | Publication date |
|---|---|
| US5128215A (en) | 1992-07-07 |
| DE69021209D1 (en) | 1995-08-31 |
| JPH04505381A (en) | 1992-09-17 |
| EP0472640B1 (en) | 1995-07-26 |
| WO1990014662A1 (en) | 1990-11-29 |
| EP0472640A1 (en) | 1992-03-04 |
| KR920701943A (en) | 1992-08-12 |
| DE69021209T2 (en) | 1996-03-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |