CA2192074A1 - Repositionable pressure sensitive adhesive comprising tacky microspheres - Google Patents
Repositionable pressure sensitive adhesive comprising tacky microspheresInfo
- Publication number
- CA2192074A1 CA2192074A1 CA002192074A CA2192074A CA2192074A1 CA 2192074 A1 CA2192074 A1 CA 2192074A1 CA 002192074 A CA002192074 A CA 002192074A CA 2192074 A CA2192074 A CA 2192074A CA 2192074 A1 CA2192074 A1 CA 2192074A1
- Authority
- CA
- Canada
- Prior art keywords
- parts
- acrylate
- weight
- sheet material
- microspheres
- 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
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F265/00—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00
- C08F265/04—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00 on to polymers of esters
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J7/00—Adhesives in the form of films or foils
- C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
- C09J7/38—Pressure-sensitive adhesives [PSA]
- C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
- C09J7/385—Acrylic polymers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- C08L33/04—Homopolymers or copolymers of esters
- C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
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- 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
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/14—Layer or component removable to expose adhesive
- Y10T428/1405—Capsule or particulate matter containing [e.g., sphere, flake, microballoon, etc.]
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- 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
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/14—Layer or component removable to expose adhesive
- Y10T428/1462—Polymer derived from material having at least one acrylic or alkacrylic group or the nitrile or amide derivative thereof [e.g., acrylamide, acrylate ester, etc.]
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- 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
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
- Y10T428/254—Polymeric or resinous material
-
- 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
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/27—Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.]
- Y10T428/273—Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.] of coating
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- 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
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/28—Web or sheet containing structurally defined element or component and having an adhesive outermost layer
-
- 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
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/28—Web or sheet containing structurally defined element or component and having an adhesive outermost layer
- Y10T428/2848—Three or more layers
-
- 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
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/28—Web or sheet containing structurally defined element or component and having an adhesive outermost layer
- Y10T428/2852—Adhesive compositions
- Y10T428/2861—Adhesive compositions having readily strippable combined with readily readhearable properties [e.g., stick-ons, etc.]
Abstract
A coated sheet material comprising a backing and a coating of repositionable pressure-sensitive adhesive comprising a plurality of solid microspheres, a polymeric stabilizer and a surfactant. Processes for preparing solid microspheres are also disclosed.
Description
~ W 096/01295 2 ~ 9 2 0 7 4 p~ e ~ 7 REPOSITIONABLE PRESSURE SENSITIVE ADHESIVE COMPRISING TACKY MICROSPHERES
Technical Field This invention relates to ~pG~iliùnaule adhesives ,t:po,;Lion; I
5 a.ll,e~h/c coated sheet materials and p~ul~esses for preparing repositionable adhesives.
Background of the l.r./e..lion Pu ,;Liùnable adhesives are those that allow for the placer"r "L
of an article cor,L~;" ,g such an adhesive onto a receptor in an exact position because the article can be adjusted relative to the receptor after initial placement.
In some instances, the adhesive can be designated ,~.o~ilionable or repeatedly reusable. As used herein the term ~po,;L;ùnable'' refers to the ability to be ,t:peaLeclly adhered to and removed from a substrate without substantial loss of adhesion capability. Such adhesives exhibit apgressive tack but low peel adhesion properties thus allowing repeated reusability. Co"""e,~.ial products such as the 3M brand Post-lt Notes display such adhesive Chc"a~.Le~i~Li~.S.
Solid inherently tacky, ela:nulllelic uliclu:,ph~ are known in the art to be useful in r~po:,;liùnaule adhesive a, ~ lions.
~1 .u:~phe~t: based adhesives are thought to perform well in such ns at least in part due to their "self-cleaning nature wherein substrate CO~La~ tend to be pushed aside and trapped between the ",;",u,yhe~t:s as the adhesive is applied. Upon removal the adhesive still presents a relatively unco"la",;"aL~d surface for ~_p~ n to the substrate.
One problem a:~OI iaLt:d with these types of adhesives has been "~i- ,ospher~ transfer, i.e. rll;clusuher~ loss to a receptor. That W096/01295 2 1 920 74 P~ r-~77 is, Illic,u.~.h_rtz loss from a substrate on which the microsphere has been po~;Liolled to a surface to which the substrate has been adhered by the Illiclu~plle,~:. To alleviate this problem, binders or primers have been utilized.
Summary of the Invention In one aspect, the present invention provides a sheet material comprising a backing and a coating of lepo~i~ionab,le pressure-sensitive adhesive coated on at least one major surface of the backing, the adhesive comprising i) a plurality of polymeric, solid, ela:,lu"~eric microspheres that are the reaction product of reactants comprising pol~",eri~able starting materials col",uri .iug at least one C4 - Cl4 alkyl (meth)acrylate monomer and at least one polar comonomer which, if the polar co",ono"ler co",p(;ses a d;,so~ hle proton, has no clissoc;,.hle proton having a Kd of greater than 10-3;
ii) a polymeric stabilizer in an amount of between about 0.1 and about 3 parts by weight per 100 parts by weight of the ",i.,,u ,,uhe,es Ipreferably about 0.5 to about 2 parts by wei~ht per 100 parts by weight of the microspheres); and iii) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the Illi~;lu~,uhe~t:s (preferably about no greater than 3 parts by weight and most preferably in the range of 0.1 to about 1.5 parts by weight per 100 parts by weight of the Illiulûsphelrs). As used in this arF'i Lion, the notation "(meth)acrylateN refers to acrylate and methacrylate.
In another aspect, the present invention provides a one step suspension polyll,e,i~dLion process for preparing polymeric, solid, elc,~Lu,,,eric ,,,ic,u~uhe,~ COlllp~i~ill9 the steps of:
al stirring or agitating a mixture cc,r",uri~ing polymerizable monomer starting materials colllpriai~lg at least one C4 - Cl4 alkyl ~ W096/01295 21 92~ 74 r~." "7 (meth)acrylate monomer and a polar co",ono",er which, if the polar cr,",ono",er co"",,i ,.s a di-50~ :~I.I, proton, has no d;sso~ le proton having a Kd greater than 10 3; an initiator for the poly",~, monomer starting materials; a polymeric stabilizer in an amount in the range of 0.1 to about 3 parts by weight per 100 parts by weight of the poly.,,c,i monomer starting materials; a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of polylllc,i~aLlc monomer, prerclabl~ no greater than about 3 parts by weight and most preferably in the range of 0.1 to 1.5 parts by weight; and water to form an oil in water suspension; and b) polymerizing the (meth)acrylate monomer(s) and the polar co",ono",dr(s); wherein solid ,,,ic,r,sphelc~ are provided.
In yet another aspect, the present invention provides a two-step suspension poly",e,i~dLion process for preparing polymeric, solid, elc:,Lu,,,c,ic ,,,i~,~.sphe,c, from poly,,,c,i ' monomer starting materials, the process crj",~ i"g the steps of:
a) stirring or agitating a mixture co"",ri~i"g at least one C4 - C14 alkyl (meth)acrylate Illollol"dr an initiator for the ",ono",er, a polymeric stabilizer in an amount of about 0.1 to about 3 parts by weight per 100 parts by weight of the poly",eri~able monomer starting materials; a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the polylllcli~dblc monomer starting materials, preferably no greater than 3 parts by weight and most prcrc,dLly in the range of 0.5 to 2 parts by weight;
and water to form an oil in water suspension;
b) at least partially polymerizing the poly,,,c,i~cble monomer starting materials;
c) adding to the suspension a polar comonomer(s) which, if the polar co",ol-o",er(s) comprise a d:.co~ k. proton, have no dicsoci~h4 proton having a Kd greater than 10-3; and wos6/012s5 21 q~07~ r~l~u~ ~ ~
d) continuing the poly",~ d~ion of the polyllleli~dlJI~, monomer starting materials; wherein ~ .l u ~,uhclds are provided.
It is desirable to make a pressure sensitive adhesive with improved adhesion and yet Idpo ~;~ior~ without fiber pick-up.
5 There are several criteria indicated fûr such an adhesive.
First, a solid, well-formed microsphere is desirable because such Illi~,luspll~,ds provide Idapoailiu~ y at high ",;c,u~,he(e coating weights because of improved topology of the coating surface.
Second, it is desirable to have improved adhesion to particular surfaces, such that the adhesive strength remains constant or slightly builds after a period of time.
Third, it is desirable that the impurities in the coating solution, such as surfactants, polymeric protective colloids, be minimized to 15 maintain the high adhesion level. Typically, this would result in coatings that are process unstable because of shear. Surprisingly, this problem is ~" "i"aLad and the ~ui~.~u:.~)hel~s of the present invention improve process stability because of shear in fluid handlin~.
Fourth, it is desirable to develop a luiclusphe~ adhesive that 20 adheres tû a substrate ûr backin~ and easily remûves from applied surfaces without bdlla~llillg or leaving an adhesive residue on the applied surface.
The Illi~.luaphel~:-collLa;llillg adhesives prepared according to the pluceases of the present invention can advantageously be coated 25 from water, thus ,~" uillaLillg li",ildLions ~soc~ d with solvent coating. FulLll~llllul~, the col"Li"aLiùn of surfactant and stabilizer as used in the present invention produces Illi~,luaplldl~a that are essellLiJlly all soiid ~meth)acrylate Illicluaphel~a~ although there may be a detectable number of hollow or hollow-appearin~ Illiulua~ d 30 without ind;~aLil)ns of coag~ tk~n or ag9loillelalion durin~ the 2~ 92074 WO 96101295 P~ ?7 suspension poly",ari~alion process. Depending on the colllonolln~ra selected and the reaction/poly",a,i~aliu" cùndiliùns the ~ u~Jhe~
maybe up to 90-95% solvent soluble. Further, depend;.,g on the co",' Idlion of co",ol,rj",e,a surfactant and stabilizer the 5 I,,ic,u:.plle,~:, are water ui~p~laiL'~ that is the Illiulu~phel~s can be diluted with water and formulated with water soluble material but once dried do not redisperse in water.
The microsphere-conl..;., ,9 adhesives of the present invention advantageously exhibit improved release chald~n~ri:>lius (higher 10 adhesion without fiber pick-up) excellent ancllo,dge to a coated substrate excellent adhesion to various surfaces (textured surfaces glass, vinyll, and improved shear holding (hang adhesion). All the improved chala~leri~ s are achievable without losing a soft smooth removal that is a non-raspy removal.
Desr,i~,lion of the F~c:r~ d ~r"Lc ~- llr~lll(s) The microspheres obtained in the present invention are the reaction product of (i) at least one alkyl (meth)acrylate ester wherein the alkyl group contains four to about 14 carbon atoms pl~r~rc,bly four to about 10 carbon atoms and (ii~ a polar cor"ono",er which if 20 it co,,,udses ~J;ssoc; ~I~! proton, has no d:ssoc;~ proton having a Kd of greaterthan 10-3, p,t:r~ldbl~rnogreaterthan 101 Useful alkyl (meth)acrylâte ~"ono"~e~a are those monofunctional unsaturated (meth)acrylate esters the alkyl groups of which have from 4 to 14 carbon atoms. Such (meth)acrylates are 25 oleophilic water .I;i.pr-,:,ib!a and are essa.,Li.,llv water insoluble.
Fu~ lhe~ ort:, useful (meth)acrylates are those that as homopolymers generally have a glass transition temperature below about -20~C or if a COII laLion of monomers is used such co", ~dlion would produce a copolymer or terpolymer generally having a glass transition wos6/012ss 21 92074 P~ ~~"7 temperature below about -20~C. Non' ~ r~ examples of such (meth~acrylates included but are not limited to, isooctyl acrylate, methyl-2-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, isodecyl 5 methacrylate, t-butyl acrylate, t-butyl methacrylate, isobornyl acrylate, methyllllelllacrylate~ isononyl acrylate, isodecyl acrylate and the like, and co",t laliun thereof.
Preferred alkyl (meth)acrylate Illonolllel~ include isooctyl acrylate, isononyl acrylate, isoamyl acrylate, isodecyl acrylate, 2-10 ethylhexyl acrylate, n-butyl acrylate, sec-butyl acrylate and mixtures thereof.
Suitable polar colllol-olllel:, may or may not contain a d: jo~ hydrogen. In any case, the polar co",ono"~er is one that exhibits a balance of solubility prupe, Lies in the alkyl (meth)acrylate 15 monomer and water phases of the dispe,~iol- obtained when the alkyl (meth)acrylate monomer is dispersed in water to provide a ~i~"iri.,~..,l amount of polar co",onrjl"el at or near the interfaces of the two phases, that is, ditr~ llLial solubility of the polar co",ono",er tends to result in a higher poly",e,i~dblc co,-cenl,dlion at or near the surface 20 of the alkyl (meth)acrylate monomer droplet. Inclusion of the polar Colllollollldl provides ,lliulu~Jheres that generally exhibit less tendency to transfer to substrates to which adl,esi:c coated sheet materials of the invention have been adhered.
One class of suitable polar co,,lonolllel~ having no d ~ :- ' 'g 25 proton are amino-functional IllOnOllldl~ having a nucleus or portion of the nucleus of the general formula (1):
o CH2=CHR1--C--L--R2--(NR3R4)X
(1) ~\ WO96/01295 2 1 92074 P~
wherein Rl is H, -CH3, {:H2CH3, cyano or cdll~oxy."~:~l,yl;
- R2 is a hydrocarbyl radical co~ .ri:,i"g 1 to about 4 carbon stoms;
R3 and R4 are i"dependc"~ly H or an alkyl group co, I; ~9 1 to about 4 carbon atoms or an arylalkyl group or together form a cyclic or heterocyclic moiety, with the proviso that R3 and R4 together do not exceed a total of 8 carbon atoms;
L is a carbon-carbon bond, 0, NH or S; and x is an integer of 1 to 3.
Nor "iLi"g examples of co",ono"~e~ of formula 1 include N,N-dimethyl-aminoethyl(meth)acrylate, N,N-dimethyld" ,inop, upyl-(meth~acrylate, t-butyld",i"ot:~l,yl(meth~acrylate and N,N-diethyld" ,i"oacrylate.
Another class of suitable polar co",ono",er~ having no d ~~ proton are hydroxylic comonomers having a nucleus or portion of the nucleus of the general formula (2~:
1~l CH2=CHR1--C--L--R2--(~ H~x (2 wherein R, is H, -CH3, -CH2CH3, cyano or carboxymethyl;
R2 is a hydrocarbyl radical comprising 1 to about 4 carbon atoms;
L is a carbon-carbon bond, 0, NH or S; and x is an integer of 1 to 3.
No, ~ "iLillg examples of polar co",onol"e,~ of formula 2 include hydroxyethyl (meth~acrylate, 3-hydroxypropyl (meth~acrylate, glycerol mono(meth~acrylate and 4-hydroxybutyl (meth~acrylate.
wo96/0129~ 2 1 9 2 0 7 ~
Yet another class of suitable polar comonomers having no ,i~ ' 'e proton are amido-functional Illonolll~l~ having a nucleus or portion of the nucleus of the general formula (3):
CH2=CHR1--C--NR3R4 (3) wherein R~ is H, -CH3, -CH2CH3, cyano or carboxymethyl; and R3 and R4 are i"depende"~ly H or an alkyl group co"L~.:., ,9 1 to about 4 carbon atoms or an arylalkyl group or together form a cyclic 10 or ht:~lu~ ,l;c moiety, with the proviso that R3 and R4 together do not exceed a total of 8 carbon atoms.
Nonlimiting examples of polar co",ono",er~ of formula 3 include N-vinyl pyrrolidone, N-vinyl caplula~Lal~l~ acrylamide or N,N-dimethyl acrylamide.
Nonlimiting examples of other suitable polar cor"onol"e,:, that do not fall within the above classes and have no dissociable proton include (meth)acrylonitrile, furfuryl Imeth)acrylate and tetrahydrofurfuryl ~meth)acrylate, 2-vinyl pyridine, and 4-vinyl pyridine.
Suitable polar Illonolllel5 having a diss~ ~ ' ' proton are organic carboxylic acids co""~,i,i"g three to about 8 carbon atoms and having generally one to about 4 carboxylic acid moieties.
Nonlimiting examples of polar ",ono"n:r~ that comprise a ~I j50~ le proton, but not a d;~ hydrogen having a Kd of greater than about 103 include acrylic acid, methacrylic acid, itaconic acid, fumaric acid and crotonic acid.
Generally, the relative amounts by weight of the alkyl (meth)acryiate monomer(s) and the polar COlllOllOlllt:l used will be about 99.5/0.5 to 85/15, and will pl~rt:labl; be 98/2 to 92/8.
01295 r ~ 7 The ,,,icrûsphert: adhesive co,,,uu~ on may also contain a cn~ S - Ihil19 agent. Examples of useful Clu~ Ihil 19 agents include but are not limited to: multifunctional (meth)acrylate(s) e.s.
butanediol diacrylate or h~anediol diacrylate or other multifunctional 5 ..r~ s ,he,~ such as divinylua"~ene and mixtures thereof. When used u~u ,~li,)her(s) is (are) added at a level of up to about 0.15 equivalent weight percent, plt:r~lably up to about 0.1 equivalent weight percent, of the total polylll~ aLle col,,uosiLium The Illi~ lu~Jhel~s of the present invention are prepared by 10 suspension poly",e,i~aliun using either a one-step or two-step process as described in detail below. Suspension poly~e~i~aLiûn is a procedure wherein a monomer is dispersed in a medium (usually aqueous) in which it is insoluble. The poly",e,i~aLioll is allowed to proceed within the individual polymer droplets. Monomer soluble 15 free-radical initiators are used. The kinetics and the ",achan;~", are essentially those for the co,,t:~uolldi~lg bulk polymerization under the same condiLiol-s of temperature and initiator concer,L'aliom Initiators effecting pol~""e,i~alion are those that are normally suitable for free-radical polymerization of acrylate monomers.
20 Examples of such initiators include II,a""ally activated initiators such as azo compounds, hyd~upe~uxides, peroxides and the like and phui ~ilialur~ such as be,,~opl,c,,one benzoin ethyl ether and 2 2 -dimethoxy-2-phenyl act:lopl-enolle. Other suitable initiators include lauryol peroxide and bis(t-t-butyl cyclohexyl)peroxy dicaluunal~. The 25 initiator is present in a catalytically effect amount sufficient to bring about complete monomer conversion in a pr~:del~""i"ed time span and temperature range.
Palalll~ r~ that affect the col~cellLlaLiol~ of initiator employed include the type of initiator and particular monomer and/or monomers 30 involved. It is believed that catalytically effective conce~LlaLions W096/01295 2 ~ 9 2 0 7 4 ~o range from about 0.10 to about 1 percent by weight of the total ,~lonolllal:~ and more plar~ uly~ from about 0.25 to about 0.70 percent by weight ",ouo",e,:. and/or ",ono",e,a.
A polymeric stabilizer is also utilized. Advantageously, the 5 presence of the stabilizer permits use of relatively low amounts of surfactant while still obtaining desirable solid Illk lu:"Jhelas~
aLiùn of the amount of surfactant and the relatively low amount of polymeric stabilizer employed desirably permits the ability of coating the aqueous d;,pe,~;on of finished ",icrospheres directly 10 onto a backing to obtain an adhesive-coated sheet material exhibiting desirable adhesive p,upe,~i~s.
Preferred polymeric stabiiizers that assist in the plt:paldLiOIl of the l~ u~her~s typically have an interfacial tension sufficient to stabilize final polymerized droplets and prevent agglo"~e~aLiom 15 Interfacial tension herein means the value determined between the monomer phase and a 1.0 percent by weight aqueous solution of the stabilizer and such interfacial tensions are generally above about 15.0 dynes per cell~ al.
Exemplary stabilizers include salts of polyacrylic acids of 20 greater than 5000 mûlecular weight (e.~q., the ammonium, sodium, lithium and potassium salts), carboxy modified polyacrylamides (e.q., Cyanamer A-370 from American Cyanamid), copolymers of acrylic acid and di",t:ll"rld"l;"oethyl",all,a~.,ylate and the like, quarternary amines (e.q., General Analine and Film's Gafquat 755, a qudr~e",kt:d 25 polyvinyl-pyrolidone copolymer, or Union Carbide's "JR-400n, a qua~ It:llli~ed amine substituted cellulosic), and carboxy modified ~ ~"UI~ ci~:c (e.g., Hercules' Natrosol CMC Type 7L, sodium carboxy methycellulose) .
Generally, the polymeric stabilizer will be present in the 30 reaction mixture in an amount by weight of about 0.1 to about 3 ~ WO96/01295 21 q20 74 r~ 7 psrts by weight per 100 parts of pol~l",e,i "~ monomer, and more preferably will be present in an amount by weight of about 0.5 to about 1.5 parts by weight per 100 parts of pol~",eri~able monomer.
Polymeric sl ' :" :. can be added to the reaction mixture either 5 singly or as mixture of several stabilizers, the amount of which does not exceed that of a single stabilizer.
In addition, a surfactant is utilized in a concehl,d~ion greater than the critical micelle conce"l~dlion (CMC) which is defined as that minimum conc~ dLion that is necessary for micelle formation. This 10 conce"l,dLion can vary with each emulsifier. Generally, the surfactants will be present in the reaction mixture in an amount by weisht of no greater than 5 parts by weight per 100 parts by weight of polyl"eli~able monomer, preferably no greater than 3 parts by weight, and most pn:r~:ldl,ly in the range of 0.1 to 1.5 parts by 15 weight per 100 parts by weight of polyllleli~aL;le monomer.
Surfactants can be added to the reaction mixture either singly or as mixture of several surfactants, the amount of which does not exceed that of a single surfactant.
Useful surfactants include anionic, cationic or nonionic 20 surfactants and included but are not limited to anionic surfactants, such as alkyl aryl sulfonates, for example sodium dodecylbenzene sulfonate and sodium decylbenzene, sodium and ammonium salts of alkyl sulfates, for example sodium lauryl sulfate, and ammonium lauryl sulfate; nonionic surfactants, such as ethoxylated oleyl alcohol 25 and polyoxyethylene octylphenyl ether; and cationic surfactants, such as a mixture of alkyl dimethylbenzyl ammonium chlorides wherein the alkyl chain contains from 10 to 18 carbon atoms.
Amphoteric emulsifiers are also usefui in the present invention and include for example betaine derivatives, sulfobetaine derivatives, N-wo96/01295 2 1 ~ 2~ 74 ~ 2 ~ 7 fatty ,,", loulup;.~lla~, N-fatty aminobutyrate, alkyl i", ' " ,e and mixtures thereof.
To initiate the pol"~ dliul~ reaction, a sufficient number of free radicals must be present. This may be achieved through several means that are well known in the art, such as heat or radiation free-radical initiation. For example, heat or radiation can be applied to initiate the pol~,r,,,t:,i~dliun of the l"ollo"lt:,~, which is an ~xull,~"";u reaction. However, it is preferred to apply heat until thermal cleco~,,uosiLioll of the initiators generates a sufficient number of free radicals to begin the reaction. The temperature at which this occurs varies greatly dependi"g upon the initiator used.
In addition, deoxygenation of the poly,,,e,i~c,Liun reaction mixture is often desirable. It is well known that oxygen dissolved in the reaction mixture can inhibit pol~l",e,i~alion and it is desirable to expel this dissolved oxygen. Although, an inert gas bubbled into the reaction vessel or through the reaction mixture is an effective means of deoxygenation, other L~h n 1 ~Pc for deoxy~enation that are COlu,udi'' ' with suspension pol~rllle,i~aLion can be used. Typically, nitrogen is used to deoxygenate, although any of the Group VIIIA
(CAS versiûn) inert gases, or carbon dioxide are also suitable.
While specific time and stirring speed pdlall~ are depencle"l upon l"olloi"e,~, initiators, it is desirable to p,~:di~pe,~e the reaction mixture until the reaction mixture reaches a state where the average monomer droplet size is between about 511m and 8011m and pldrt:ldbly between 3011m and 60um. The average particle size decreases with increased and p~olonged agitation of the reaction mixture.
The stirring and the nitrogen purge are maintained throughout the reaction period. Initiation is begun by heating the reaction mixture. Following poly."~ aLiùn, the reaction mixture is cooled.
~¦ WO96/01295 21 92074 r~,"~ '777 In the one-step process both the alkyl (meth)acrylate monomer and the polar co""~ou",er are present together in the suspension at the initiation of pol~r",~ aLiom In the two-step process the polar co,,,unolll~:l is typically added after the initial exotherm resulting from 5 poly.ll~ alion of the alkyl (meth)acrylate monomer has peaked, but could be added at any point after polyllleli~aLion has started.
Following polylll~ dliun, a stable aqueous suspension of n,ic,u:"uheres at room temperature is obtained. The suspension may have non-volatile solids contents of from about 10 to about 60 10 percent by weight. Upon prolonged standing, the suspension typically separates into two phases, one phase being aqueous and ~:,e"Li~:ly free of polymer and the other phase being an aqueous suspension of the polymeric microspheres, that is, the microsphere-rich phase. The aqueous suspension of ~ u~Jhe~ may be utilized 15 immediately following polylll~li~alion~ because the suspension of Illi~.lu~hel~s of the present invention is particularly stable to a~ lo~ lalion or coa~ ti~n under room temperature co".Jilions.
Advantageously, the l~ u~phert:s of the present invention can be easily coated from an aqueous solution. Surprisingly, the 20 microspheres of the present invention are well suited for conventional coating techniques and have enhanced fluid processing ~;1 lal d~,Lt:ri~Li~.s.
Separation of the ~ic~u ,~,he,e-rich phase provides an aqueous suspension having a non-volatile solids content, which if diluted with 25 an additional amount of water, will readily redisperse upon shaking or other means of agitation. Generally, this aqueous suspension can be coated onto a backing or other substrate being employed using conventional coating methods, such as slot die coating to provide an adhesive coating. The adhesive coating which, when dried, 30 ple~:rdbly exhibits a dry coating weight in the range of 0.4 to about . _ . _ _ _ . . . . . . . . . _ _ _ _ _ _ _ Wo96101295 2l q2074 r~1,u.............................. ~ 7 1~
2 grams per square foot to provide an adl,e~iJc coated sheet material in which the adhesive coating cG,,,udses polymeric uli~lua~uhelt:s~
polymeric stabilizer and surfactant. Alternatively, the ",ic,~ heres may be isolated in an or~anic solvent if desired prior to coating them 5 onto the backing.
Plupei1ids of the pressure-sensitive adhesives of the present invention can be altered by the addition of a tackifying resin(s) and/or pl~Li..i~er(s). Preferred tackifiers for use herein include hyd,ugella1~d rosin esters co"""e,~ "y available from such COIlluall as Hercules, 10 Inc. under the 11adellallles of Foral and Pentalyn . Tackifying resins also include those based on t-butyl styrene. Useful pla ~ la include but are not limited to dioctyl phthalate, 2-ethyl hexyl phG:"~ha1t:, tricresyl phOspha~: and the like. If such tackifiers and/or pla:~Li~ dl:~ are used, the amounts used in the adhesive mixture are 15 amounts effective for the known uses of such additives.
Optionally, adjuvants, such as, colorants, fillers, 5 ' " ~..:., pressure-sensitive latex binders and various other polymeric additives can be utilized. If such adjuvants are used, the amounts used in the adhesive mixture are amounts effective for the known uses of such 20 adjuvants.
Suitable backing or substrate materials for use in the present invention include, but are not limited to, paper, plastic films, cellulose acetate, ethyl cellulose, woven or nonwoven fabric formed of synthetic or natural materials, metal, metallized polymeric film, 25 ceramic sheet material and the like. Generally the backing or substrate material is about 50 ,um to about 155 llm in thickness, although thicker and thinner backing or substrate materials are not precluded .
The present invention is further illustrated by the following 30 examples, but the particular materials and amounts thereof recited in ~ WO96101295 2 ~ 920 74 p ~ 7 these examples as well as other conditions and details should not be construed to unduly limit this invention. Ali materials are cu"""c~ 'y available or known to those skilled in the art unless otherwise stated or apparent. The following examples are illustrative 5 in nature and are not intended to limit the invention in any way.
Test r~ odj Static Shear Hold Static shear hold is d~Lt:""i"ed as the hanging time for an adhesive coated substrate appiied to a stainless steel plate when a 10 weight is attached. The procedure followed is:
A 1 x 1/2 inch ~2.5 X 3.8 cm) sample of the adhesive coated substrate is adhered to a polished steel plate with a 4.5 pound (2 kg) roller. The plate is hung vertically and a 1 kg weight is attached to the free end of the adhesive stripe. A timer is started and the length 15 of time for the adhesive coated sample to release and fall from the steel plate is measured in minutes.
Peel Adhesion Peel adhesion is the force required to remove a polyester film applied to the coated test material measured at a specific angle and 20 rate of removal. In the examples, this force is exl.ressed in grams per 1.25 inches (3.2 cm) width of coated sheet. The procedure followed is:
A strip, 1.25 inches (3.2 cm) wide of polyester film is applied to the horizontal surface of a coated sample fixed on a test plate. A
25 4.5 Ib. ~2 kg) hard rubber roller is used to apply the strip. The free end of the polyester film is attached to the adhesion tester load cell so that the angle of removal will be 90 degrees. The test plate is then clamped in the jaws of the tensile testing machine that is capable of moving the plate away from the load cell at a constant WO96101295 21 q2074 r~l~u~ / ~
rate of 12 inches (31 cm) per minute. A load cell reading in grams per 1.25 inches 13.2 cm) of coated strip is recorded as the polyester film is peeled from the coated samples. The samples are tested three times. The average of the three tests is reported below.
5 ~~ v~ h~.~ Transf~r M- u~uh&~: transfer for the purposes of this test is defined as the amount of ~ u~ h~e that transfers to an applied paper when the coated sample is removed from the paper. It is measured as the percent of the area covered with ~I~iclu~uhe~t:s. The procedure 10 followed is:
A three-quarter (3/4") (1.9 cm) wide strip of lUi~ lo:.phelt:
coated sample is adhered to a clean area of a clay coated paper coml,l~,~ i. lly available as Kromcoat, for a few seconds using the l"e. l,c",ical rolling action provided by an TLMI release and adhesion 15 tester and then is removed at a 90~ degree angle at a constant rate.
The clay coated strip is then surveyed by an image processor through a video camera and the percent ll,iulu:",hel~ coverage of the viewed area is recorded. Ten fields were surveyed on each test sample and the average of these readinss is recorded.
Glossary AA - acrylic acid ACM - acrylamide CRA - crotonic acid FA - fumaric acid HEMA - hydroxyethyl methacrylate IOA- isooctyl acrylate IPA- isopropyl alcohol ITA - itaconic acid NVP - N-vinyl pyrrolidone Wo 96/01295 r~ 7 E~ 'es Example 7 To a 2 liter, 3 necked flask equipped with II,e""o",eLer, reflux conde,)~e" I,,ecl,a,l;cal stirrer and nitrogen inlet tube, were char~qed 739 grams of deionized water, and 9.6 ~qrams of Acrysol A3 (Lladeualllè for â 25 percent solids aqueous solution of polyacrylic acid of 190,000 molecular weight, col""~eu "y available from the Rohm and Haas Company) and 10 grams of Triton X 200 (Lladellallle for a 28 ~h solids aqueous suspension of sodium alkylaryl polyether sulfonate, cor"",ercially available from Rohm and Haas Companyl.
The contents of the flask were then agitated and conce"L,dLed ammonium hydroxide was added there to until a pH of 7.0 was obtained and heated 70~C. To this solution were added 239 grams of isooctylacrylate and 0.8 grams of Perkadox 16N (Lladenallle for a 94.5~h active BIS (4-tert-butyl cyclohexyl) peroxydicarbonate initiator collllllel~ially available from AKZ0 Chemicals, Inc. The agitation was set at 600 revolutions per minute (rpml and the reaction mixture was purged with nitrogen. The stirring and nitrogen purge were ~"~ L~ ed throu~hout the reaction period. The reaction mixture was l~ uLailled at 65~C to initiate the reaction. The reaction became exuLl,e""i" after a few minutes of heating. After the exotherm had peaked (80~C), 14.8 grams of acrylic acid was added slowly to the reaction flask and the batch was heated to 90~C for two hours. The reaction mixture was then cooled to room temperature and filtered through a cheese cloth. Very little coagulum was observed to be present.
The vinylic moiety, the amount of vinylic moiety, the peel adhesion, and the Illic~ hele transfer are su,,,,,,a,i~ed in Table 1.
WO 96/01295 2 1 9 Z ~ 7 ~ 7 ~
Examplo 2-5 Examples 2-5 illustrate the use of various vinylic moieties. The Illic~ "Jhe,~:s of these Examples were prepared in arcoldal-ce with the procedures outlined in Example 1. The vinylic moiety, the 5 amount of vinylic moiety, the peel adhesion, and the ",;~ ,u .~ er~
transfer are s~""",a,i~td in Table 1.
C~ Example C1 Comparative Example C1 was prepared in acco~dance with the procedures outlined in Example 1 except that no acrylic acid was 10 added after exotherm.
The test results are reported in Table 1.
Table 1 Vinylic Peel Monomer MoietyAdhesion r.~ osphe,e Ex (gm) (9/1.25 Transfer i-.) AA ~-. 9 1 7.1 6.9 HEM . 9 ~ .2 1.2 NVP . 9 .~ 1.09 Acm ~ . 9 ~. 1.3 AA/Acm 9. / .5 . 0.30 Example 6 To a two liter, 3-necked flask equipped with a ther",or,lek:r, ,lleclldlliGdl stirrer and nitrogen inlet tube, was charged 650 grams of deionized water, 5.8 gm of Triton X 200 (tradename for 28 % solids aqueous suspension of sodium alkyl arylpolyether sulfonate con""t:" i.,l'y available from Rohm and Haas Company), 14 gm of 20 Acumer IS-30 (Lladellallle for a 25 percent solids aqueous solution of polyacrylic acid of 190,000 molecular weight, co"~ en i~3"y available from Rohm and Haas Company), 2.8 ~qm of conce,lLlaLed ammonium wo 96/01295 P~ 777 hydroxide (a alu;~.hiO~ Lli~ amount of base to give ammonium polyacrylate), and 14 gms of acrylic acid. To this solution was added 350 gms of isooctylacrylate and 1.1 gms of Perkadox 16N
(~ladel~ lle for a 95% active bis(4-tert-butylcyclohexyl) 5 perox~ alLlùllalt: initiator to"""~cially available from AKZ0 Chemicals, Inc.). The agitation was set at 450 revolutions per minute (RPM) and the reaction mixture was heated to 45~C and purged with nitrogen. The stirring, nitrogen purge and temperature was " ,l. :.,ed throughout the reaction period, the reaction was 10 ~xulhellllic after a few minutes and peaked at 69~C. The batch was rllaiulailled at 45~C for two more hours, cooled, and filtered through cheese cloth. Very little coagulum was found to be present. The resulting suspension was found to contain microâpheres of an average particle size of 77.6 microns which on creaming had a lower~5 phase solids of 2% by weight. M uSCOp;C e~alllilla6on showed the u~Jher~ to be a solid sphere.
Examples 7-15 Examples 7-15 included in Table 2 below illustrate the use of various polar vinylic monomers, stabilizers or surfactants. The 20 microspheres of these examples were prepared in accolda"ce with the procedures outlined in Example 6. The polar monomer, surfactant type, and stabilizer type along with the particle size, coagulum and lower phase solids are also reported. The data shows that at relatively low conce,,l,aliùns of surfactant (0.5% of monomer 25 conce,lllalion) stable ",i~ ,u~.I,e,l: d;;"uelaions can be made with the addition of a stabilizer and a polar vinylic to",ono",er.
Cr~ Example C2 Comparative Example C2 was prepared in acco, ,lance with the procedure described in Example 6, except no stabilizer was added to WO96101295 2 ~ q2074 P~
the reaction mixture. The results are st,"""a,i~:d in Table 2 and indicate that without the stabilizer, the reaction mixture coa9tll~tpc Cr,.,.~,a, 'i~_ Ex~mplo C3 Comparative Example C3 was prepared in accordallce with 5 Example 6, except no colllunollldr was added in the reaction mixture.
The results are sullllllali~d in Table 2 and indicates that without the co",ono",d" the reaction mixture coagulates.
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Ex~mple 16 To a 2 liter, 3 necked flask equipped with LhvllllulllvLer~ reflux condvnse~mlldclla";vàl stirrer and nitrogen inlet tube were charrved 650 vqm of deionized water, and 7 ovm of Goodrite K702 (Lladenallld for a 25% solids aqueous solution of polyacrylic acid of 240,000 molecular weight, volllllldll ~Iy available from B.F. Goodrich Company) and 1.8 rvms of Siponate DS10 (Lladellallle for sodium dodev~/lbv,,cene sulfonate, CCIlllllvdrl ~ ~y available from Alcolac, Inc.) The contents of the flask were then agitated and concvnLlaLvd ammonium hydroxide was added thereto until a pH of 7.0 was obtained. The flask was heated to 50~C and 14 gms of N-vinylpyrrolidone, 1.1 ovms of Perkadox 16N (Llad~nallld for 94.5~/0 active bis-(4-tert-butyl cyclohexyl) peroxyd;va~lvondLv initiator col,,,,,e,vivlly available from AKZ0 Chemical Inc.), and 350 rvms of isooctylacrylate were added and the agitation was set at 410 rpm.
The reaction mixture was purAved with nitrogen and became e,~o~ llic after a few minutes of heatin~. The 50~C batch temperature was maintained for five hours and the mixture cooled to room temperature and filtered throu~qh cheese cloth. Very little COâgUIâtiOn WâS observed ând the resulting suspension WâS found to contâin ,,,iv,cs,l)hervs of ân averâvqe particle size ûf 40.5 microns.
This suspension was made into a coatinvq by addin~q 153 gms to 13 Qms of the suspension of an isooctylacrylate/acrylic acid copolymer latex (monomer ratio was 96/4) and 3 ovms of Acrysol ASE95 (an 18% solids acrylic thickener cor"~ vre "y available from Rohm and Haas Company) and 32 voms of water. This coatinvo was mixed and neutralized with concellLlaLvd ammonium hydroxide to pH 7.0 and coated on a primed backing of bond paper at a rate of 0.8 rvm/sq. ft.
The results are tabulated in Table 3 below.
WO 96/01295 P~ 7 Table 3 eel adhesion to polyester (grams/1.25 inches) l25.1 eel adhesion to bond paper (grams/inch) 3.4 ercent ~ .lu~uht~ transfer J.8%
tatic shear hold 653 minutes Examples 17-19 Examples 17-19 illustrate the improvement in anchorage by 5 i"",t:a:,i"g the amount of acrylic acid in the ",i..,u:,phe,t:~. These were prepared according the procedure described in Example 1 and were made into a coating with 4~,6 of an acrylate terpolymer latex containing an N-alkyl substituted acrylamide available from BF
Goodrich under the Lladenallle of Hycar 2600 x 222 and 1% of an 10 acid co"l..;., ,9 acrylic emulsion copolymer thickener available from Rohm and Haas Co. under the tradename Acrylsol ASE 95 NP. The coatings were applied to a primed bond paper using coating procedures known in the art. The test results are su"""a,i~,3d in Table 4.
15 Cv~ a~..ti~_ Examples C4 ~aJ and ~bJ
Comparative Examples C4 (a) and ~b) were prepared according to the procedure described in Examples 17-19 except there was no acrylic acid added. To prepared a ~ u:~phelt: suspension that did not coagulate and was coatable, sodium propinate and ethylene 20 amine hyd,u. hloride were added in place of the co-monomer (C4 (a)) and (C4 (b)), respectively.
wos6/012ss 21 92074 r~l~e~ t -~7 1~
Table 4 Example 1\1 u~,uh~l~ Peel Adhesion Percent IOA/AA Ratio(gm/1.25~ to M;~,u~ he~
polyest r film Tr sfer C~ a) 10 . .9 C~ b) 10 . .4 . 7 . I . . 4.2 ~ O. 1 The data shows a decrease in transfer as the percent of acrylic acid increases.
5 Examples 20-22 Exampies 20-22 illustrate the build of adhesion on a~qin~ usin~q different polar co",onr,"~ ,. These examples were prepared usin~q the procedure described in Example 1 and coatin~ using techniques known to those skilled in the art. Peel adl,esiolls were measured 10 accordin~ to the above-described procedures. The test results are su, 1 Il l IC~ J in Table 5.
~i WO96/01295 21 92074 r~ 7 Table 6 ~tO Polar Example ¦ Co~ùllo~ l Peel Adhesior (gm/inc~) Bond Bond Vinyl Vinyl Initial3-days Initial 3-da /s humidity humic ty 4~h AA 98.1 202.8 108.9 36.
21 AA 120.9 161.9 114.5 48.
22 4~~0 NVP/0.5% 113.6 181.5 132.8 233.8 AA
The data shows an increase in the adhesion on aging with acrylic acid MSA against bond paper and a decrease in adhesion 5 when aged against a vinyl notebook. However, N-vinyl pyrrolidone ,,,i~rû~he,,:s show a sig"iricd"l increase in adhesion to vinyl on aging at high humidity (80% RH at 70~F).
Examples 23-25 Examples 23-25 illustrate the effect of polar co",ono",er in 10 isooctylacrvlate ",i. ,u ,~,he,es when hanging on a vertical surface, such as a painted metal. The samples were prepared as described in Example 1 and were cut to apply a 1 " x 1.5~ (2.5 x 3.8 cm) area of adhesive coated paper to the metal surface. The paper was then hung vertically with a 1 kg weight attached to the paper extending 15 from the edge of the painted metal. The time before shear failure was then recorded. The results are su"""d,i~ed in Table 6.
Tabie 6 Static Shear - Example % Polar Co""~,1oi"el Hold Time to Painted Metal nir _~ 4~/0 AA 4.' -- 4~/0 HEMA/1% AA . 9.
4~/0 NVP/0.5% AA 1 4.
wo96lol2ss 21 92074 P~ r ~~77 Various Illn~l;r;~ ns and a~ dlions of this invention will become apparent to those skilled in the art without departing from the scope and principies of this invention, and it should be 5 u"del~luod that this invention is not be unduly limited to the illustrative ellluodi~e~ set forth he,~ i.,abuve. All p~.l.'ka~ s and patents are illcG,uoldlt:d herein by reference to the same extent as if each individual publication or patent was s~.e"i~i 'y and individually indicated to be ill~ olyordl~:d by reference.
Technical Field This invention relates to ~pG~iliùnaule adhesives ,t:po,;Lion; I
5 a.ll,e~h/c coated sheet materials and p~ul~esses for preparing repositionable adhesives.
Background of the l.r./e..lion Pu ,;Liùnable adhesives are those that allow for the placer"r "L
of an article cor,L~;" ,g such an adhesive onto a receptor in an exact position because the article can be adjusted relative to the receptor after initial placement.
In some instances, the adhesive can be designated ,~.o~ilionable or repeatedly reusable. As used herein the term ~po,;L;ùnable'' refers to the ability to be ,t:peaLeclly adhered to and removed from a substrate without substantial loss of adhesion capability. Such adhesives exhibit apgressive tack but low peel adhesion properties thus allowing repeated reusability. Co"""e,~.ial products such as the 3M brand Post-lt Notes display such adhesive Chc"a~.Le~i~Li~.S.
Solid inherently tacky, ela:nulllelic uliclu:,ph~ are known in the art to be useful in r~po:,;liùnaule adhesive a, ~ lions.
~1 .u:~phe~t: based adhesives are thought to perform well in such ns at least in part due to their "self-cleaning nature wherein substrate CO~La~ tend to be pushed aside and trapped between the ",;",u,yhe~t:s as the adhesive is applied. Upon removal the adhesive still presents a relatively unco"la",;"aL~d surface for ~_p~ n to the substrate.
One problem a:~OI iaLt:d with these types of adhesives has been "~i- ,ospher~ transfer, i.e. rll;clusuher~ loss to a receptor. That W096/01295 2 1 920 74 P~ r-~77 is, Illic,u.~.h_rtz loss from a substrate on which the microsphere has been po~;Liolled to a surface to which the substrate has been adhered by the Illiclu~plle,~:. To alleviate this problem, binders or primers have been utilized.
Summary of the Invention In one aspect, the present invention provides a sheet material comprising a backing and a coating of lepo~i~ionab,le pressure-sensitive adhesive coated on at least one major surface of the backing, the adhesive comprising i) a plurality of polymeric, solid, ela:,lu"~eric microspheres that are the reaction product of reactants comprising pol~",eri~able starting materials col",uri .iug at least one C4 - Cl4 alkyl (meth)acrylate monomer and at least one polar comonomer which, if the polar co",ono"ler co",p(;ses a d;,so~ hle proton, has no clissoc;,.hle proton having a Kd of greater than 10-3;
ii) a polymeric stabilizer in an amount of between about 0.1 and about 3 parts by weight per 100 parts by weight of the ",i.,,u ,,uhe,es Ipreferably about 0.5 to about 2 parts by wei~ht per 100 parts by weight of the microspheres); and iii) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the Illi~;lu~,uhe~t:s (preferably about no greater than 3 parts by weight and most preferably in the range of 0.1 to about 1.5 parts by weight per 100 parts by weight of the Illiulûsphelrs). As used in this arF'i Lion, the notation "(meth)acrylateN refers to acrylate and methacrylate.
In another aspect, the present invention provides a one step suspension polyll,e,i~dLion process for preparing polymeric, solid, elc,~Lu,,,eric ,,,ic,u~uhe,~ COlllp~i~ill9 the steps of:
al stirring or agitating a mixture cc,r",uri~ing polymerizable monomer starting materials colllpriai~lg at least one C4 - Cl4 alkyl ~ W096/01295 21 92~ 74 r~." "7 (meth)acrylate monomer and a polar co",ono",er which, if the polar cr,",ono",er co"",,i ,.s a di-50~ :~I.I, proton, has no d;sso~ le proton having a Kd greater than 10 3; an initiator for the poly",~, monomer starting materials; a polymeric stabilizer in an amount in the range of 0.1 to about 3 parts by weight per 100 parts by weight of the poly.,,c,i monomer starting materials; a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of polylllc,i~aLlc monomer, prerclabl~ no greater than about 3 parts by weight and most preferably in the range of 0.1 to 1.5 parts by weight; and water to form an oil in water suspension; and b) polymerizing the (meth)acrylate monomer(s) and the polar co",ono",dr(s); wherein solid ,,,ic,r,sphelc~ are provided.
In yet another aspect, the present invention provides a two-step suspension poly",e,i~dLion process for preparing polymeric, solid, elc:,Lu,,,c,ic ,,,i~,~.sphe,c, from poly,,,c,i ' monomer starting materials, the process crj",~ i"g the steps of:
a) stirring or agitating a mixture co"",ri~i"g at least one C4 - C14 alkyl (meth)acrylate Illollol"dr an initiator for the ",ono",er, a polymeric stabilizer in an amount of about 0.1 to about 3 parts by weight per 100 parts by weight of the poly",eri~able monomer starting materials; a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the polylllcli~dblc monomer starting materials, preferably no greater than 3 parts by weight and most prcrc,dLly in the range of 0.5 to 2 parts by weight;
and water to form an oil in water suspension;
b) at least partially polymerizing the poly,,,c,i~cble monomer starting materials;
c) adding to the suspension a polar comonomer(s) which, if the polar co",ol-o",er(s) comprise a d:.co~ k. proton, have no dicsoci~h4 proton having a Kd greater than 10-3; and wos6/012s5 21 q~07~ r~l~u~ ~ ~
d) continuing the poly",~ d~ion of the polyllleli~dlJI~, monomer starting materials; wherein ~ .l u ~,uhclds are provided.
It is desirable to make a pressure sensitive adhesive with improved adhesion and yet Idpo ~;~ior~ without fiber pick-up.
5 There are several criteria indicated fûr such an adhesive.
First, a solid, well-formed microsphere is desirable because such Illi~,luspll~,ds provide Idapoailiu~ y at high ",;c,u~,he(e coating weights because of improved topology of the coating surface.
Second, it is desirable to have improved adhesion to particular surfaces, such that the adhesive strength remains constant or slightly builds after a period of time.
Third, it is desirable that the impurities in the coating solution, such as surfactants, polymeric protective colloids, be minimized to 15 maintain the high adhesion level. Typically, this would result in coatings that are process unstable because of shear. Surprisingly, this problem is ~" "i"aLad and the ~ui~.~u:.~)hel~s of the present invention improve process stability because of shear in fluid handlin~.
Fourth, it is desirable to develop a luiclusphe~ adhesive that 20 adheres tû a substrate ûr backin~ and easily remûves from applied surfaces without bdlla~llillg or leaving an adhesive residue on the applied surface.
The Illi~.luaphel~:-collLa;llillg adhesives prepared according to the pluceases of the present invention can advantageously be coated 25 from water, thus ,~" uillaLillg li",ildLions ~soc~ d with solvent coating. FulLll~llllul~, the col"Li"aLiùn of surfactant and stabilizer as used in the present invention produces Illi~,luaplldl~a that are essellLiJlly all soiid ~meth)acrylate Illicluaphel~a~ although there may be a detectable number of hollow or hollow-appearin~ Illiulua~ d 30 without ind;~aLil)ns of coag~ tk~n or ag9loillelalion durin~ the 2~ 92074 WO 96101295 P~ ?7 suspension poly",ari~alion process. Depending on the colllonolln~ra selected and the reaction/poly",a,i~aliu" cùndiliùns the ~ u~Jhe~
maybe up to 90-95% solvent soluble. Further, depend;.,g on the co",' Idlion of co",ol,rj",e,a surfactant and stabilizer the 5 I,,ic,u:.plle,~:, are water ui~p~laiL'~ that is the Illiulu~phel~s can be diluted with water and formulated with water soluble material but once dried do not redisperse in water.
The microsphere-conl..;., ,9 adhesives of the present invention advantageously exhibit improved release chald~n~ri:>lius (higher 10 adhesion without fiber pick-up) excellent ancllo,dge to a coated substrate excellent adhesion to various surfaces (textured surfaces glass, vinyll, and improved shear holding (hang adhesion). All the improved chala~leri~ s are achievable without losing a soft smooth removal that is a non-raspy removal.
Desr,i~,lion of the F~c:r~ d ~r"Lc ~- llr~lll(s) The microspheres obtained in the present invention are the reaction product of (i) at least one alkyl (meth)acrylate ester wherein the alkyl group contains four to about 14 carbon atoms pl~r~rc,bly four to about 10 carbon atoms and (ii~ a polar cor"ono",er which if 20 it co,,,udses ~J;ssoc; ~I~! proton, has no d:ssoc;~ proton having a Kd of greaterthan 10-3, p,t:r~ldbl~rnogreaterthan 101 Useful alkyl (meth)acrylâte ~"ono"~e~a are those monofunctional unsaturated (meth)acrylate esters the alkyl groups of which have from 4 to 14 carbon atoms. Such (meth)acrylates are 25 oleophilic water .I;i.pr-,:,ib!a and are essa.,Li.,llv water insoluble.
Fu~ lhe~ ort:, useful (meth)acrylates are those that as homopolymers generally have a glass transition temperature below about -20~C or if a COII laLion of monomers is used such co", ~dlion would produce a copolymer or terpolymer generally having a glass transition wos6/012ss 21 92074 P~ ~~"7 temperature below about -20~C. Non' ~ r~ examples of such (meth~acrylates included but are not limited to, isooctyl acrylate, methyl-2-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, isodecyl 5 methacrylate, t-butyl acrylate, t-butyl methacrylate, isobornyl acrylate, methyllllelllacrylate~ isononyl acrylate, isodecyl acrylate and the like, and co",t laliun thereof.
Preferred alkyl (meth)acrylate Illonolllel~ include isooctyl acrylate, isononyl acrylate, isoamyl acrylate, isodecyl acrylate, 2-10 ethylhexyl acrylate, n-butyl acrylate, sec-butyl acrylate and mixtures thereof.
Suitable polar colllol-olllel:, may or may not contain a d: jo~ hydrogen. In any case, the polar co",ono"~er is one that exhibits a balance of solubility prupe, Lies in the alkyl (meth)acrylate 15 monomer and water phases of the dispe,~iol- obtained when the alkyl (meth)acrylate monomer is dispersed in water to provide a ~i~"iri.,~..,l amount of polar co",onrjl"el at or near the interfaces of the two phases, that is, ditr~ llLial solubility of the polar co",ono",er tends to result in a higher poly",e,i~dblc co,-cenl,dlion at or near the surface 20 of the alkyl (meth)acrylate monomer droplet. Inclusion of the polar Colllollollldl provides ,lliulu~Jheres that generally exhibit less tendency to transfer to substrates to which adl,esi:c coated sheet materials of the invention have been adhered.
One class of suitable polar co,,lonolllel~ having no d ~ :- ' 'g 25 proton are amino-functional IllOnOllldl~ having a nucleus or portion of the nucleus of the general formula (1):
o CH2=CHR1--C--L--R2--(NR3R4)X
(1) ~\ WO96/01295 2 1 92074 P~
wherein Rl is H, -CH3, {:H2CH3, cyano or cdll~oxy."~:~l,yl;
- R2 is a hydrocarbyl radical co~ .ri:,i"g 1 to about 4 carbon stoms;
R3 and R4 are i"dependc"~ly H or an alkyl group co, I; ~9 1 to about 4 carbon atoms or an arylalkyl group or together form a cyclic or heterocyclic moiety, with the proviso that R3 and R4 together do not exceed a total of 8 carbon atoms;
L is a carbon-carbon bond, 0, NH or S; and x is an integer of 1 to 3.
Nor "iLi"g examples of co",ono"~e~ of formula 1 include N,N-dimethyl-aminoethyl(meth)acrylate, N,N-dimethyld" ,inop, upyl-(meth~acrylate, t-butyld",i"ot:~l,yl(meth~acrylate and N,N-diethyld" ,i"oacrylate.
Another class of suitable polar co",ono",er~ having no d ~~ proton are hydroxylic comonomers having a nucleus or portion of the nucleus of the general formula (2~:
1~l CH2=CHR1--C--L--R2--(~ H~x (2 wherein R, is H, -CH3, -CH2CH3, cyano or carboxymethyl;
R2 is a hydrocarbyl radical comprising 1 to about 4 carbon atoms;
L is a carbon-carbon bond, 0, NH or S; and x is an integer of 1 to 3.
No, ~ "iLillg examples of polar co",onol"e,~ of formula 2 include hydroxyethyl (meth~acrylate, 3-hydroxypropyl (meth~acrylate, glycerol mono(meth~acrylate and 4-hydroxybutyl (meth~acrylate.
wo96/0129~ 2 1 9 2 0 7 ~
Yet another class of suitable polar comonomers having no ,i~ ' 'e proton are amido-functional Illonolll~l~ having a nucleus or portion of the nucleus of the general formula (3):
CH2=CHR1--C--NR3R4 (3) wherein R~ is H, -CH3, -CH2CH3, cyano or carboxymethyl; and R3 and R4 are i"depende"~ly H or an alkyl group co"L~.:., ,9 1 to about 4 carbon atoms or an arylalkyl group or together form a cyclic 10 or ht:~lu~ ,l;c moiety, with the proviso that R3 and R4 together do not exceed a total of 8 carbon atoms.
Nonlimiting examples of polar co",ono",er~ of formula 3 include N-vinyl pyrrolidone, N-vinyl caplula~Lal~l~ acrylamide or N,N-dimethyl acrylamide.
Nonlimiting examples of other suitable polar cor"onol"e,:, that do not fall within the above classes and have no dissociable proton include (meth)acrylonitrile, furfuryl Imeth)acrylate and tetrahydrofurfuryl ~meth)acrylate, 2-vinyl pyridine, and 4-vinyl pyridine.
Suitable polar Illonolllel5 having a diss~ ~ ' ' proton are organic carboxylic acids co""~,i,i"g three to about 8 carbon atoms and having generally one to about 4 carboxylic acid moieties.
Nonlimiting examples of polar ",ono"n:r~ that comprise a ~I j50~ le proton, but not a d;~ hydrogen having a Kd of greater than about 103 include acrylic acid, methacrylic acid, itaconic acid, fumaric acid and crotonic acid.
Generally, the relative amounts by weight of the alkyl (meth)acryiate monomer(s) and the polar COlllOllOlllt:l used will be about 99.5/0.5 to 85/15, and will pl~rt:labl; be 98/2 to 92/8.
01295 r ~ 7 The ,,,icrûsphert: adhesive co,,,uu~ on may also contain a cn~ S - Ihil19 agent. Examples of useful Clu~ Ihil 19 agents include but are not limited to: multifunctional (meth)acrylate(s) e.s.
butanediol diacrylate or h~anediol diacrylate or other multifunctional 5 ..r~ s ,he,~ such as divinylua"~ene and mixtures thereof. When used u~u ,~li,)her(s) is (are) added at a level of up to about 0.15 equivalent weight percent, plt:r~lably up to about 0.1 equivalent weight percent, of the total polylll~ aLle col,,uosiLium The Illi~ lu~Jhel~s of the present invention are prepared by 10 suspension poly",e,i~aliun using either a one-step or two-step process as described in detail below. Suspension poly~e~i~aLiûn is a procedure wherein a monomer is dispersed in a medium (usually aqueous) in which it is insoluble. The poly",e,i~aLioll is allowed to proceed within the individual polymer droplets. Monomer soluble 15 free-radical initiators are used. The kinetics and the ",achan;~", are essentially those for the co,,t:~uolldi~lg bulk polymerization under the same condiLiol-s of temperature and initiator concer,L'aliom Initiators effecting pol~""e,i~alion are those that are normally suitable for free-radical polymerization of acrylate monomers.
20 Examples of such initiators include II,a""ally activated initiators such as azo compounds, hyd~upe~uxides, peroxides and the like and phui ~ilialur~ such as be,,~opl,c,,one benzoin ethyl ether and 2 2 -dimethoxy-2-phenyl act:lopl-enolle. Other suitable initiators include lauryol peroxide and bis(t-t-butyl cyclohexyl)peroxy dicaluunal~. The 25 initiator is present in a catalytically effect amount sufficient to bring about complete monomer conversion in a pr~:del~""i"ed time span and temperature range.
Palalll~ r~ that affect the col~cellLlaLiol~ of initiator employed include the type of initiator and particular monomer and/or monomers 30 involved. It is believed that catalytically effective conce~LlaLions W096/01295 2 ~ 9 2 0 7 4 ~o range from about 0.10 to about 1 percent by weight of the total ,~lonolllal:~ and more plar~ uly~ from about 0.25 to about 0.70 percent by weight ",ouo",e,:. and/or ",ono",e,a.
A polymeric stabilizer is also utilized. Advantageously, the 5 presence of the stabilizer permits use of relatively low amounts of surfactant while still obtaining desirable solid Illk lu:"Jhelas~
aLiùn of the amount of surfactant and the relatively low amount of polymeric stabilizer employed desirably permits the ability of coating the aqueous d;,pe,~;on of finished ",icrospheres directly 10 onto a backing to obtain an adhesive-coated sheet material exhibiting desirable adhesive p,upe,~i~s.
Preferred polymeric stabiiizers that assist in the plt:paldLiOIl of the l~ u~her~s typically have an interfacial tension sufficient to stabilize final polymerized droplets and prevent agglo"~e~aLiom 15 Interfacial tension herein means the value determined between the monomer phase and a 1.0 percent by weight aqueous solution of the stabilizer and such interfacial tensions are generally above about 15.0 dynes per cell~ al.
Exemplary stabilizers include salts of polyacrylic acids of 20 greater than 5000 mûlecular weight (e.~q., the ammonium, sodium, lithium and potassium salts), carboxy modified polyacrylamides (e.q., Cyanamer A-370 from American Cyanamid), copolymers of acrylic acid and di",t:ll"rld"l;"oethyl",all,a~.,ylate and the like, quarternary amines (e.q., General Analine and Film's Gafquat 755, a qudr~e",kt:d 25 polyvinyl-pyrolidone copolymer, or Union Carbide's "JR-400n, a qua~ It:llli~ed amine substituted cellulosic), and carboxy modified ~ ~"UI~ ci~:c (e.g., Hercules' Natrosol CMC Type 7L, sodium carboxy methycellulose) .
Generally, the polymeric stabilizer will be present in the 30 reaction mixture in an amount by weight of about 0.1 to about 3 ~ WO96/01295 21 q20 74 r~ 7 psrts by weight per 100 parts of pol~l",e,i "~ monomer, and more preferably will be present in an amount by weight of about 0.5 to about 1.5 parts by weight per 100 parts of pol~",eri~able monomer.
Polymeric sl ' :" :. can be added to the reaction mixture either 5 singly or as mixture of several stabilizers, the amount of which does not exceed that of a single stabilizer.
In addition, a surfactant is utilized in a concehl,d~ion greater than the critical micelle conce"l~dlion (CMC) which is defined as that minimum conc~ dLion that is necessary for micelle formation. This 10 conce"l,dLion can vary with each emulsifier. Generally, the surfactants will be present in the reaction mixture in an amount by weisht of no greater than 5 parts by weight per 100 parts by weight of polyl"eli~able monomer, preferably no greater than 3 parts by weight, and most pn:r~:ldl,ly in the range of 0.1 to 1.5 parts by 15 weight per 100 parts by weight of polyllleli~aL;le monomer.
Surfactants can be added to the reaction mixture either singly or as mixture of several surfactants, the amount of which does not exceed that of a single surfactant.
Useful surfactants include anionic, cationic or nonionic 20 surfactants and included but are not limited to anionic surfactants, such as alkyl aryl sulfonates, for example sodium dodecylbenzene sulfonate and sodium decylbenzene, sodium and ammonium salts of alkyl sulfates, for example sodium lauryl sulfate, and ammonium lauryl sulfate; nonionic surfactants, such as ethoxylated oleyl alcohol 25 and polyoxyethylene octylphenyl ether; and cationic surfactants, such as a mixture of alkyl dimethylbenzyl ammonium chlorides wherein the alkyl chain contains from 10 to 18 carbon atoms.
Amphoteric emulsifiers are also usefui in the present invention and include for example betaine derivatives, sulfobetaine derivatives, N-wo96/01295 2 1 ~ 2~ 74 ~ 2 ~ 7 fatty ,,", loulup;.~lla~, N-fatty aminobutyrate, alkyl i", ' " ,e and mixtures thereof.
To initiate the pol"~ dliul~ reaction, a sufficient number of free radicals must be present. This may be achieved through several means that are well known in the art, such as heat or radiation free-radical initiation. For example, heat or radiation can be applied to initiate the pol~,r,,,t:,i~dliun of the l"ollo"lt:,~, which is an ~xull,~"";u reaction. However, it is preferred to apply heat until thermal cleco~,,uosiLioll of the initiators generates a sufficient number of free radicals to begin the reaction. The temperature at which this occurs varies greatly dependi"g upon the initiator used.
In addition, deoxygenation of the poly,,,e,i~c,Liun reaction mixture is often desirable. It is well known that oxygen dissolved in the reaction mixture can inhibit pol~l",e,i~alion and it is desirable to expel this dissolved oxygen. Although, an inert gas bubbled into the reaction vessel or through the reaction mixture is an effective means of deoxygenation, other L~h n 1 ~Pc for deoxy~enation that are COlu,udi'' ' with suspension pol~rllle,i~aLion can be used. Typically, nitrogen is used to deoxygenate, although any of the Group VIIIA
(CAS versiûn) inert gases, or carbon dioxide are also suitable.
While specific time and stirring speed pdlall~ are depencle"l upon l"olloi"e,~, initiators, it is desirable to p,~:di~pe,~e the reaction mixture until the reaction mixture reaches a state where the average monomer droplet size is between about 511m and 8011m and pldrt:ldbly between 3011m and 60um. The average particle size decreases with increased and p~olonged agitation of the reaction mixture.
The stirring and the nitrogen purge are maintained throughout the reaction period. Initiation is begun by heating the reaction mixture. Following poly."~ aLiùn, the reaction mixture is cooled.
~¦ WO96/01295 21 92074 r~,"~ '777 In the one-step process both the alkyl (meth)acrylate monomer and the polar co""~ou",er are present together in the suspension at the initiation of pol~r",~ aLiom In the two-step process the polar co,,,unolll~:l is typically added after the initial exotherm resulting from 5 poly.ll~ alion of the alkyl (meth)acrylate monomer has peaked, but could be added at any point after polyllleli~aLion has started.
Following polylll~ dliun, a stable aqueous suspension of n,ic,u:"uheres at room temperature is obtained. The suspension may have non-volatile solids contents of from about 10 to about 60 10 percent by weight. Upon prolonged standing, the suspension typically separates into two phases, one phase being aqueous and ~:,e"Li~:ly free of polymer and the other phase being an aqueous suspension of the polymeric microspheres, that is, the microsphere-rich phase. The aqueous suspension of ~ u~Jhe~ may be utilized 15 immediately following polylll~li~alion~ because the suspension of Illi~.lu~hel~s of the present invention is particularly stable to a~ lo~ lalion or coa~ ti~n under room temperature co".Jilions.
Advantageously, the l~ u~phert:s of the present invention can be easily coated from an aqueous solution. Surprisingly, the 20 microspheres of the present invention are well suited for conventional coating techniques and have enhanced fluid processing ~;1 lal d~,Lt:ri~Li~.s.
Separation of the ~ic~u ,~,he,e-rich phase provides an aqueous suspension having a non-volatile solids content, which if diluted with 25 an additional amount of water, will readily redisperse upon shaking or other means of agitation. Generally, this aqueous suspension can be coated onto a backing or other substrate being employed using conventional coating methods, such as slot die coating to provide an adhesive coating. The adhesive coating which, when dried, 30 ple~:rdbly exhibits a dry coating weight in the range of 0.4 to about . _ . _ _ _ . . . . . . . . . _ _ _ _ _ _ _ Wo96101295 2l q2074 r~1,u.............................. ~ 7 1~
2 grams per square foot to provide an adl,e~iJc coated sheet material in which the adhesive coating cG,,,udses polymeric uli~lua~uhelt:s~
polymeric stabilizer and surfactant. Alternatively, the ",ic,~ heres may be isolated in an or~anic solvent if desired prior to coating them 5 onto the backing.
Plupei1ids of the pressure-sensitive adhesives of the present invention can be altered by the addition of a tackifying resin(s) and/or pl~Li..i~er(s). Preferred tackifiers for use herein include hyd,ugella1~d rosin esters co"""e,~ "y available from such COIlluall as Hercules, 10 Inc. under the 11adellallles of Foral and Pentalyn . Tackifying resins also include those based on t-butyl styrene. Useful pla ~ la include but are not limited to dioctyl phthalate, 2-ethyl hexyl phG:"~ha1t:, tricresyl phOspha~: and the like. If such tackifiers and/or pla:~Li~ dl:~ are used, the amounts used in the adhesive mixture are 15 amounts effective for the known uses of such additives.
Optionally, adjuvants, such as, colorants, fillers, 5 ' " ~..:., pressure-sensitive latex binders and various other polymeric additives can be utilized. If such adjuvants are used, the amounts used in the adhesive mixture are amounts effective for the known uses of such 20 adjuvants.
Suitable backing or substrate materials for use in the present invention include, but are not limited to, paper, plastic films, cellulose acetate, ethyl cellulose, woven or nonwoven fabric formed of synthetic or natural materials, metal, metallized polymeric film, 25 ceramic sheet material and the like. Generally the backing or substrate material is about 50 ,um to about 155 llm in thickness, although thicker and thinner backing or substrate materials are not precluded .
The present invention is further illustrated by the following 30 examples, but the particular materials and amounts thereof recited in ~ WO96101295 2 ~ 920 74 p ~ 7 these examples as well as other conditions and details should not be construed to unduly limit this invention. Ali materials are cu"""c~ 'y available or known to those skilled in the art unless otherwise stated or apparent. The following examples are illustrative 5 in nature and are not intended to limit the invention in any way.
Test r~ odj Static Shear Hold Static shear hold is d~Lt:""i"ed as the hanging time for an adhesive coated substrate appiied to a stainless steel plate when a 10 weight is attached. The procedure followed is:
A 1 x 1/2 inch ~2.5 X 3.8 cm) sample of the adhesive coated substrate is adhered to a polished steel plate with a 4.5 pound (2 kg) roller. The plate is hung vertically and a 1 kg weight is attached to the free end of the adhesive stripe. A timer is started and the length 15 of time for the adhesive coated sample to release and fall from the steel plate is measured in minutes.
Peel Adhesion Peel adhesion is the force required to remove a polyester film applied to the coated test material measured at a specific angle and 20 rate of removal. In the examples, this force is exl.ressed in grams per 1.25 inches (3.2 cm) width of coated sheet. The procedure followed is:
A strip, 1.25 inches (3.2 cm) wide of polyester film is applied to the horizontal surface of a coated sample fixed on a test plate. A
25 4.5 Ib. ~2 kg) hard rubber roller is used to apply the strip. The free end of the polyester film is attached to the adhesion tester load cell so that the angle of removal will be 90 degrees. The test plate is then clamped in the jaws of the tensile testing machine that is capable of moving the plate away from the load cell at a constant WO96101295 21 q2074 r~l~u~ / ~
rate of 12 inches (31 cm) per minute. A load cell reading in grams per 1.25 inches 13.2 cm) of coated strip is recorded as the polyester film is peeled from the coated samples. The samples are tested three times. The average of the three tests is reported below.
5 ~~ v~ h~.~ Transf~r M- u~uh&~: transfer for the purposes of this test is defined as the amount of ~ u~ h~e that transfers to an applied paper when the coated sample is removed from the paper. It is measured as the percent of the area covered with ~I~iclu~uhe~t:s. The procedure 10 followed is:
A three-quarter (3/4") (1.9 cm) wide strip of lUi~ lo:.phelt:
coated sample is adhered to a clean area of a clay coated paper coml,l~,~ i. lly available as Kromcoat, for a few seconds using the l"e. l,c",ical rolling action provided by an TLMI release and adhesion 15 tester and then is removed at a 90~ degree angle at a constant rate.
The clay coated strip is then surveyed by an image processor through a video camera and the percent ll,iulu:",hel~ coverage of the viewed area is recorded. Ten fields were surveyed on each test sample and the average of these readinss is recorded.
Glossary AA - acrylic acid ACM - acrylamide CRA - crotonic acid FA - fumaric acid HEMA - hydroxyethyl methacrylate IOA- isooctyl acrylate IPA- isopropyl alcohol ITA - itaconic acid NVP - N-vinyl pyrrolidone Wo 96/01295 r~ 7 E~ 'es Example 7 To a 2 liter, 3 necked flask equipped with II,e""o",eLer, reflux conde,)~e" I,,ecl,a,l;cal stirrer and nitrogen inlet tube, were char~qed 739 grams of deionized water, and 9.6 ~qrams of Acrysol A3 (Lladeualllè for â 25 percent solids aqueous solution of polyacrylic acid of 190,000 molecular weight, col""~eu "y available from the Rohm and Haas Company) and 10 grams of Triton X 200 (Lladellallle for a 28 ~h solids aqueous suspension of sodium alkylaryl polyether sulfonate, cor"",ercially available from Rohm and Haas Companyl.
The contents of the flask were then agitated and conce"L,dLed ammonium hydroxide was added there to until a pH of 7.0 was obtained and heated 70~C. To this solution were added 239 grams of isooctylacrylate and 0.8 grams of Perkadox 16N (Lladenallle for a 94.5~h active BIS (4-tert-butyl cyclohexyl) peroxydicarbonate initiator collllllel~ially available from AKZ0 Chemicals, Inc. The agitation was set at 600 revolutions per minute (rpml and the reaction mixture was purged with nitrogen. The stirring and nitrogen purge were ~"~ L~ ed throu~hout the reaction period. The reaction mixture was l~ uLailled at 65~C to initiate the reaction. The reaction became exuLl,e""i" after a few minutes of heating. After the exotherm had peaked (80~C), 14.8 grams of acrylic acid was added slowly to the reaction flask and the batch was heated to 90~C for two hours. The reaction mixture was then cooled to room temperature and filtered through a cheese cloth. Very little coagulum was observed to be present.
The vinylic moiety, the amount of vinylic moiety, the peel adhesion, and the Illic~ hele transfer are su,,,,,,a,i~ed in Table 1.
WO 96/01295 2 1 9 Z ~ 7 ~ 7 ~
Examplo 2-5 Examples 2-5 illustrate the use of various vinylic moieties. The Illic~ "Jhe,~:s of these Examples were prepared in arcoldal-ce with the procedures outlined in Example 1. The vinylic moiety, the 5 amount of vinylic moiety, the peel adhesion, and the ",;~ ,u .~ er~
transfer are s~""",a,i~td in Table 1.
C~ Example C1 Comparative Example C1 was prepared in acco~dance with the procedures outlined in Example 1 except that no acrylic acid was 10 added after exotherm.
The test results are reported in Table 1.
Table 1 Vinylic Peel Monomer MoietyAdhesion r.~ osphe,e Ex (gm) (9/1.25 Transfer i-.) AA ~-. 9 1 7.1 6.9 HEM . 9 ~ .2 1.2 NVP . 9 .~ 1.09 Acm ~ . 9 ~. 1.3 AA/Acm 9. / .5 . 0.30 Example 6 To a two liter, 3-necked flask equipped with a ther",or,lek:r, ,lleclldlliGdl stirrer and nitrogen inlet tube, was charged 650 grams of deionized water, 5.8 gm of Triton X 200 (tradename for 28 % solids aqueous suspension of sodium alkyl arylpolyether sulfonate con""t:" i.,l'y available from Rohm and Haas Company), 14 gm of 20 Acumer IS-30 (Lladellallle for a 25 percent solids aqueous solution of polyacrylic acid of 190,000 molecular weight, co"~ en i~3"y available from Rohm and Haas Company), 2.8 ~qm of conce,lLlaLed ammonium wo 96/01295 P~ 777 hydroxide (a alu;~.hiO~ Lli~ amount of base to give ammonium polyacrylate), and 14 gms of acrylic acid. To this solution was added 350 gms of isooctylacrylate and 1.1 gms of Perkadox 16N
(~ladel~ lle for a 95% active bis(4-tert-butylcyclohexyl) 5 perox~ alLlùllalt: initiator to"""~cially available from AKZ0 Chemicals, Inc.). The agitation was set at 450 revolutions per minute (RPM) and the reaction mixture was heated to 45~C and purged with nitrogen. The stirring, nitrogen purge and temperature was " ,l. :.,ed throughout the reaction period, the reaction was 10 ~xulhellllic after a few minutes and peaked at 69~C. The batch was rllaiulailled at 45~C for two more hours, cooled, and filtered through cheese cloth. Very little coagulum was found to be present. The resulting suspension was found to contain microâpheres of an average particle size of 77.6 microns which on creaming had a lower~5 phase solids of 2% by weight. M uSCOp;C e~alllilla6on showed the u~Jher~ to be a solid sphere.
Examples 7-15 Examples 7-15 included in Table 2 below illustrate the use of various polar vinylic monomers, stabilizers or surfactants. The 20 microspheres of these examples were prepared in accolda"ce with the procedures outlined in Example 6. The polar monomer, surfactant type, and stabilizer type along with the particle size, coagulum and lower phase solids are also reported. The data shows that at relatively low conce,,l,aliùns of surfactant (0.5% of monomer 25 conce,lllalion) stable ",i~ ,u~.I,e,l: d;;"uelaions can be made with the addition of a stabilizer and a polar vinylic to",ono",er.
Cr~ Example C2 Comparative Example C2 was prepared in acco, ,lance with the procedure described in Example 6, except no stabilizer was added to WO96101295 2 ~ q2074 P~
the reaction mixture. The results are st,"""a,i~:d in Table 2 and indicate that without the stabilizer, the reaction mixture coa9tll~tpc Cr,.,.~,a, 'i~_ Ex~mplo C3 Comparative Example C3 was prepared in accordallce with 5 Example 6, except no colllunollldr was added in the reaction mixture.
The results are sullllllali~d in Table 2 and indicates that without the co",ono",d" the reaction mixture coagulates.
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' E c ~ ~~ ~ i E ~ o o o -- ~ o ~ ~ ~, o o o ~ ~ ~
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WO96/01295 21 92074 r ~ v r-.77 1~
Ex~mple 16 To a 2 liter, 3 necked flask equipped with LhvllllulllvLer~ reflux condvnse~mlldclla";vàl stirrer and nitrogen inlet tube were charrved 650 vqm of deionized water, and 7 ovm of Goodrite K702 (Lladenallld for a 25% solids aqueous solution of polyacrylic acid of 240,000 molecular weight, volllllldll ~Iy available from B.F. Goodrich Company) and 1.8 rvms of Siponate DS10 (Lladellallle for sodium dodev~/lbv,,cene sulfonate, CCIlllllvdrl ~ ~y available from Alcolac, Inc.) The contents of the flask were then agitated and concvnLlaLvd ammonium hydroxide was added thereto until a pH of 7.0 was obtained. The flask was heated to 50~C and 14 gms of N-vinylpyrrolidone, 1.1 ovms of Perkadox 16N (Llad~nallld for 94.5~/0 active bis-(4-tert-butyl cyclohexyl) peroxyd;va~lvondLv initiator col,,,,,e,vivlly available from AKZ0 Chemical Inc.), and 350 rvms of isooctylacrylate were added and the agitation was set at 410 rpm.
The reaction mixture was purAved with nitrogen and became e,~o~ llic after a few minutes of heatin~. The 50~C batch temperature was maintained for five hours and the mixture cooled to room temperature and filtered throu~qh cheese cloth. Very little COâgUIâtiOn WâS observed ând the resulting suspension WâS found to contâin ,,,iv,cs,l)hervs of ân averâvqe particle size ûf 40.5 microns.
This suspension was made into a coatinvq by addin~q 153 gms to 13 Qms of the suspension of an isooctylacrylate/acrylic acid copolymer latex (monomer ratio was 96/4) and 3 ovms of Acrysol ASE95 (an 18% solids acrylic thickener cor"~ vre "y available from Rohm and Haas Company) and 32 voms of water. This coatinvo was mixed and neutralized with concellLlaLvd ammonium hydroxide to pH 7.0 and coated on a primed backing of bond paper at a rate of 0.8 rvm/sq. ft.
The results are tabulated in Table 3 below.
WO 96/01295 P~ 7 Table 3 eel adhesion to polyester (grams/1.25 inches) l25.1 eel adhesion to bond paper (grams/inch) 3.4 ercent ~ .lu~uht~ transfer J.8%
tatic shear hold 653 minutes Examples 17-19 Examples 17-19 illustrate the improvement in anchorage by 5 i"",t:a:,i"g the amount of acrylic acid in the ",i..,u:,phe,t:~. These were prepared according the procedure described in Example 1 and were made into a coating with 4~,6 of an acrylate terpolymer latex containing an N-alkyl substituted acrylamide available from BF
Goodrich under the Lladenallle of Hycar 2600 x 222 and 1% of an 10 acid co"l..;., ,9 acrylic emulsion copolymer thickener available from Rohm and Haas Co. under the tradename Acrylsol ASE 95 NP. The coatings were applied to a primed bond paper using coating procedures known in the art. The test results are su"""a,i~,3d in Table 4.
15 Cv~ a~..ti~_ Examples C4 ~aJ and ~bJ
Comparative Examples C4 (a) and ~b) were prepared according to the procedure described in Examples 17-19 except there was no acrylic acid added. To prepared a ~ u:~phelt: suspension that did not coagulate and was coatable, sodium propinate and ethylene 20 amine hyd,u. hloride were added in place of the co-monomer (C4 (a)) and (C4 (b)), respectively.
wos6/012ss 21 92074 r~l~e~ t -~7 1~
Table 4 Example 1\1 u~,uh~l~ Peel Adhesion Percent IOA/AA Ratio(gm/1.25~ to M;~,u~ he~
polyest r film Tr sfer C~ a) 10 . .9 C~ b) 10 . .4 . 7 . I . . 4.2 ~ O. 1 The data shows a decrease in transfer as the percent of acrylic acid increases.
5 Examples 20-22 Exampies 20-22 illustrate the build of adhesion on a~qin~ usin~q different polar co",onr,"~ ,. These examples were prepared usin~q the procedure described in Example 1 and coatin~ using techniques known to those skilled in the art. Peel adl,esiolls were measured 10 accordin~ to the above-described procedures. The test results are su, 1 Il l IC~ J in Table 5.
~i WO96/01295 21 92074 r~ 7 Table 6 ~tO Polar Example ¦ Co~ùllo~ l Peel Adhesior (gm/inc~) Bond Bond Vinyl Vinyl Initial3-days Initial 3-da /s humidity humic ty 4~h AA 98.1 202.8 108.9 36.
21 AA 120.9 161.9 114.5 48.
22 4~~0 NVP/0.5% 113.6 181.5 132.8 233.8 AA
The data shows an increase in the adhesion on aging with acrylic acid MSA against bond paper and a decrease in adhesion 5 when aged against a vinyl notebook. However, N-vinyl pyrrolidone ,,,i~rû~he,,:s show a sig"iricd"l increase in adhesion to vinyl on aging at high humidity (80% RH at 70~F).
Examples 23-25 Examples 23-25 illustrate the effect of polar co",ono",er in 10 isooctylacrvlate ",i. ,u ,~,he,es when hanging on a vertical surface, such as a painted metal. The samples were prepared as described in Example 1 and were cut to apply a 1 " x 1.5~ (2.5 x 3.8 cm) area of adhesive coated paper to the metal surface. The paper was then hung vertically with a 1 kg weight attached to the paper extending 15 from the edge of the painted metal. The time before shear failure was then recorded. The results are su"""d,i~ed in Table 6.
Tabie 6 Static Shear - Example % Polar Co""~,1oi"el Hold Time to Painted Metal nir _~ 4~/0 AA 4.' -- 4~/0 HEMA/1% AA . 9.
4~/0 NVP/0.5% AA 1 4.
wo96lol2ss 21 92074 P~ r ~~77 Various Illn~l;r;~ ns and a~ dlions of this invention will become apparent to those skilled in the art without departing from the scope and principies of this invention, and it should be 5 u"del~luod that this invention is not be unduly limited to the illustrative ellluodi~e~ set forth he,~ i.,abuve. All p~.l.'ka~ s and patents are illcG,uoldlt:d herein by reference to the same extent as if each individual publication or patent was s~.e"i~i 'y and individually indicated to be ill~ olyordl~:d by reference.
Claims (13)
1. A sheet material comprising a backing and a coating of repositionable pressure-sensitive adhesive coated on at least one major surface of said backing, the adhesive comprising:
i) a plurality of polymeric, solid, elastomeric microspheres that are the reaction product of reactants comprising polymerizable starting materials comprising at least one C4 - C14 alkyl (meth)acrylate monomer and at least one polar comonomer with the proviso that if the polar comonomer comprises a dissociable proton, the polar comonomer has no dissociable proton having a Kd of greater than 10-3;
ii) a polymeric stabilizer in an amount of about 0.1 to about 3 parts by weight per 100 parts by weight of the microspheres; and iii) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the microspheres.
i) a plurality of polymeric, solid, elastomeric microspheres that are the reaction product of reactants comprising polymerizable starting materials comprising at least one C4 - C14 alkyl (meth)acrylate monomer and at least one polar comonomer with the proviso that if the polar comonomer comprises a dissociable proton, the polar comonomer has no dissociable proton having a Kd of greater than 10-3;
ii) a polymeric stabilizer in an amount of about 0.1 to about 3 parts by weight per 100 parts by weight of the microspheres; and iii) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the microspheres.
2. A sheet material according to claim 1, wherein the alkyl (meth)acrylate is selected from the group consisting of isooctyl acrylate, 4-methyl-2-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, isodecyl methacrylate, isononyl acrylate, and isodecyl acrylate.
3. A sheet material according to claim 1, wherein the polar comonomer is selected from the group consisting of acrylic acid, N-vinyl pyrrolidone, N-vinyl caprolactam, vinyl pyridine, methacrylic acid, acrylamide, fumaric acid, itaconic acid, crotonic acid, acrylonitrile, methacrylonitrile, hydroxyethylacrylate, and hydroxyethyl methacrylate.
4. A sheet material according to claim 1, wherein the polymeric stabilizer is a salt of polyacrylic acid.
5. A sheet material according to claim 1, wherein the polymeric stabilizer is present in an amount of about 0.5 to about 2 parts by weight per 100 parts by weight of the microspheres.
6. A sheet material according to claim 1, wherein the surfactant is ammonium lauryl sulfate.
7. A sheet material according to claim 1, wherein the surfactant is present in an amount of no greater than 5 parts by weight per 100 parts by weight of the microspheres.
8. A sheet material according to claim 1, wherein the dry coating weight of adhesive is in the range of 0.4 to about 2 gms per square foot of surface area of the sheet material.
9. A sheet material according to claim 1, wherein the backing is about 2 to about 6 mils in thickness.
10. A one-step suspension polymerization process for preparing polymeric, solid, elastomeric microspheres comprising the steps of:
a) stirring or agitating a mixture comprising polymerizable monomer starting materials comprising (1) at least one C4 - C14 alkyl (meth)acrylate monomer and (2) a polar comonomer which, if the polar comonomer comprises a dissociable proton, has no dissociable proton having a Kd greater than 10-3; (3) a catalytically effective amount of an initiator for said polymerizable monomer starting materials; (4) a polymeric stabilizer in an amount of about 0.1 to about 3 parts by weight per 100 parts by weight of said polymerizable monomer starting materials; (5) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of said polymerizable monomer starting materials; and (6) water to form an oil in water suspension; and b) polymerizing said polymerizable monomer starting materials; wherein the microspheres are provided.
a) stirring or agitating a mixture comprising polymerizable monomer starting materials comprising (1) at least one C4 - C14 alkyl (meth)acrylate monomer and (2) a polar comonomer which, if the polar comonomer comprises a dissociable proton, has no dissociable proton having a Kd greater than 10-3; (3) a catalytically effective amount of an initiator for said polymerizable monomer starting materials; (4) a polymeric stabilizer in an amount of about 0.1 to about 3 parts by weight per 100 parts by weight of said polymerizable monomer starting materials; (5) a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of said polymerizable monomer starting materials; and (6) water to form an oil in water suspension; and b) polymerizing said polymerizable monomer starting materials; wherein the microspheres are provided.
11. A two-step suspension polymerization process for preparing polymeric, solid, elastomeric microspheres from polymerizable monomer starting materials, said process comprising the steps of:
a) stirring or agitating a mixture comprising (1) at least one C4 - C14 alkyl (meth)acrylate monomer; (2) a catalytically effective amount of an initiator for the monomer; (3) a polymeric stabilizer in an amount of about 0.1 to about 3 parts by weight per 100 parts by weight of said polymerizable monomer starting materials; (4) a surfactant in an amount of no greater than about 5 parts per 100 parts by weight of said polymerizable monomer starting materials;
and (5) water to form an oil in water suspension;
b) at least partially polymerizing the polymerizable monomer starting materials;
c) adding to said suspension a polar comonomer which, if the polar comonomer comprises a dissociable proton, has no dissociable proton having a Kd greater than 10-3; and d) continuing the polymerization of the polymerizable monomer starting materials; wherein microspheres are provided.
a) stirring or agitating a mixture comprising (1) at least one C4 - C14 alkyl (meth)acrylate monomer; (2) a catalytically effective amount of an initiator for the monomer; (3) a polymeric stabilizer in an amount of about 0.1 to about 3 parts by weight per 100 parts by weight of said polymerizable monomer starting materials; (4) a surfactant in an amount of no greater than about 5 parts per 100 parts by weight of said polymerizable monomer starting materials;
and (5) water to form an oil in water suspension;
b) at least partially polymerizing the polymerizable monomer starting materials;
c) adding to said suspension a polar comonomer which, if the polar comonomer comprises a dissociable proton, has no dissociable proton having a Kd greater than 10-3; and d) continuing the polymerization of the polymerizable monomer starting materials; wherein microspheres are provided.
12. A sheet material comprising a backing and a coating of repositionable pressure-sensitive adhesive coated on at least one major surface of said backing, the coating comprising a plurality of microspheres prepared according to the process of claim 10.
13. A sheet material comprising a backing and a coating of repositionable pressure-sensitive adhesive coated on at least one major surface of said backing, the coating comprising a plurality of microspheres, prepared by the process of claim 11.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/270,179 | 1994-07-01 | ||
| US08/270,179 US5571617A (en) | 1993-04-23 | 1994-07-01 | Pressure sensitive adhesive comprising tacky surface active microspheres |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2192074A1 true CA2192074A1 (en) | 1996-01-18 |
Family
ID=23030240
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002192074A Abandoned CA2192074A1 (en) | 1994-07-01 | 1995-05-18 | Repositionable pressure sensitive adhesive comprising tacky microspheres |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US5571617A (en) |
| EP (1) | EP0769040B1 (en) |
| JP (2) | JPH10502407A (en) |
| AU (1) | AU696481B2 (en) |
| CA (1) | CA2192074A1 (en) |
| DE (1) | DE69527846T2 (en) |
| MX (1) | MX9606613A (en) |
| TW (1) | TW450989B (en) |
| WO (1) | WO1996001295A1 (en) |
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| CA677797A (en) * | 1955-11-18 | 1964-01-14 | Minnesota Mining And Manufacturing Company | Sheet material having a pressure-sensitive adhesive coating of acrylate ester copolymer |
| US3691140A (en) * | 1970-03-09 | 1972-09-12 | Spencer Ferguson Silver | Acrylate copolymer microspheres |
| US3857731A (en) * | 1973-04-06 | 1974-12-31 | Minnesota Mining & Mfg | Acrylate microsphere-surfaced sheet material |
| US4098945A (en) * | 1973-07-30 | 1978-07-04 | Minnesota Mining And Manufacturing Company | Soft conductive materials |
| US4166152B1 (en) * | 1977-08-17 | 1999-05-18 | Minnesota Mining & Mfg | Tacky polymeric microspheres |
| US4418120A (en) * | 1982-07-19 | 1983-11-29 | Minnesota Mining And Manufacturing Co. | Tackified crosslinked acrylic adhesives |
| US4599265A (en) * | 1982-11-04 | 1986-07-08 | Minnesota Mining And Manufacturing Company | Removable pressure-sensitive adhesive tape |
| US4495318A (en) * | 1984-03-21 | 1985-01-22 | International Cube Corporation | Low tack microsphere glue |
| US4598112A (en) * | 1984-09-14 | 1986-07-01 | International Cube Corp. | Low tack cationic microsphere glue |
| US4656218A (en) * | 1985-02-08 | 1987-04-07 | Sanyo Kokusaku Pulp Co., Ltd. | Adhesive copolymer microspheres-containing aqueous suspension and method for producing the same |
| US4804688A (en) * | 1985-03-22 | 1989-02-14 | Vassileff Neiko I | Open-cell foamed gypsum insulation |
| JPH0414434Y2 (en) * | 1985-04-08 | 1992-03-31 | ||
| JPS61258854A (en) * | 1985-05-13 | 1986-11-17 | Nichiban Co Ltd | Fine sphere of crosslinked polymer of acrylic ester and production thereof |
| JPH0684490B2 (en) * | 1985-05-15 | 1994-10-26 | ニチバン株式会社 | Removable adhesive composition |
| EP0209337B1 (en) * | 1985-07-13 | 1991-03-06 | Smith & McLaurin Ltd. | Adhesives |
| US4822670A (en) * | 1985-12-18 | 1989-04-18 | Nichiban Company Limited | Removable adhesive sheet or tape |
| US4786696A (en) * | 1987-02-06 | 1988-11-22 | Minnesota Mining And Manufacturing Company | Process for the preparation of tacky polymeric microspheres |
| US5045569A (en) * | 1988-11-30 | 1991-09-03 | Minnesota Mining And Manufacturing Company | Hollow acrylate polymer microspheres |
| US5053436A (en) * | 1988-11-30 | 1991-10-01 | Minnesota Mining And Manufacturing Company | Hollow acrylate polymer microspheres |
| US4994322A (en) * | 1989-09-18 | 1991-02-19 | Minnesota Mining And Manufacturing | Pressure-sensitive adhesive comprising hollow tacky microspheres and macromonomer-containing binder copolymer |
| DE69029846T2 (en) * | 1990-01-22 | 1997-07-10 | Minnesota Mining & Mfg | Aqueous, repositionable, pressure-sensitive adhesives with high adhesion |
| US5118757A (en) * | 1990-03-26 | 1992-06-02 | Shell Oil Company | Polymer production |
| US5215818A (en) * | 1990-04-20 | 1993-06-01 | Minnesota Mining And Manufacturing Company | Pressure-sensitive adhesive comprising solid tacky microspheres and macromonomer-containing binder copolymer |
| JPH04117478A (en) * | 1990-09-07 | 1992-04-17 | Sekisui Chem Co Ltd | Sprayable pressure-sensitive adhesive composition |
-
1994
- 1994-07-01 US US08/270,179 patent/US5571617A/en not_active Expired - Lifetime
-
1995
- 1995-05-18 WO PCT/US1995/006227 patent/WO1996001295A1/en active IP Right Grant
- 1995-05-18 EP EP95919875A patent/EP0769040B1/en not_active Expired - Lifetime
- 1995-05-18 JP JP8503865A patent/JPH10502407A/en not_active Withdrawn
- 1995-05-18 DE DE69527846T patent/DE69527846T2/en not_active Expired - Lifetime
- 1995-05-18 AU AU25535/95A patent/AU696481B2/en not_active Ceased
- 1995-05-18 CA CA002192074A patent/CA2192074A1/en not_active Abandoned
- 1995-05-18 MX MX9606613A patent/MX9606613A/en unknown
- 1995-05-30 TW TW084105465A patent/TW450989B/en not_active IP Right Cessation
-
2004
- 2004-08-09 JP JP2004232491A patent/JP4763255B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| MX9606613A (en) | 1997-03-29 |
| DE69527846D1 (en) | 2002-09-26 |
| EP0769040B1 (en) | 2002-08-21 |
| TW450989B (en) | 2001-08-21 |
| AU2553595A (en) | 1996-01-25 |
| JP2004346333A (en) | 2004-12-09 |
| DE69527846T2 (en) | 2003-04-24 |
| WO1996001295A1 (en) | 1996-01-18 |
| US5571617A (en) | 1996-11-05 |
| JPH10502407A (en) | 1998-03-03 |
| AU696481B2 (en) | 1998-09-10 |
| EP0769040A1 (en) | 1997-04-23 |
| JP4763255B2 (en) | 2011-08-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |