CA2103359A1 - Pressure-sensitive adhesives - Google Patents

Abstract

The present invention provides a silicone/acrylic based pressure-sensitive adhesive composition, adhesive, and adhesive tapes prepared therefrom. The adhesive composition comprises: (a) from about 5 parts to about 95 parts by weight of acrylic monomer wherein the acrylic monomer comprises: (i) from about 50 to about 100 parts by weight of alkyl acrylate monomer, the alkyl groups of which have an average of 4 to 12 carbon atoms; and (ii) correspondingly from about 50 parts to about 0 parts by weight of a monoethylenically unsaturated copolymerizable modifier monomer; wherein the amounts of (i) and (ii) are selected such that the total amount of (i) plus (ii) equals 100 parts by weight of the acrylic monomer; (b) correspondingly from about 95 parts to about 5 parts by weight of silicone pressure-sensitive adhesive wherein the amounts of (a) and (b) are selected such that the total amount of (a) plus (b) equals 100 parts by weight; (c) about 0 part to about 5 parts by weight of a photoinitiator based upon 100 parts by weight of the acrylic monomer; and (d) about 0 to about 5 parts by weight of a crosslinker based upon 100 parts by weight of (a) plus (b).

Description

WO92/20751 PCT/US92/~120 PRESSURE-SENSITIVE ADHE~IVE8 Field of the Invention 5This invention relates to pressure-sensitive adhesive compositions, adhesives, and adhesive tapes, specifically silicone/acrylic based pressure-sensitive adhesives.

10Backqround of the Invention Pressure-sensitive adhesives (PSAs) have been known and used for a long time in the art. Some of the com~on pressure-sensitive adhesives are formulations based upon acrylates, natural rubbers, synthetic 15 rubbers, vinyl acetates, and silicones. The PSAs are typically formulated for end use, often in a solvent or waterborne system. Acrylate PSAs are of particular utility in that they are relatively low in cost, adhere well to a variety of different surfaces, and can be 20 formulated to build adhesion to a surface. However, acrylate PS~s typically have poor high temperature performance and poor low temperature performance.
Examples of such acrylate PSAs are disclosed in U.S.
Patent No. Re 24,906 (Ulrich).
In recent times, there has been a need to reduce solvent pollution by using solventless systems in order to prepare pressure-sensitive adhesives. Substantially solvent free acrylate pressure-sensitive adhesi~es are disclosed in U~S. Patent No. 4,181,752 ~Martens) 30 wherein alkyl acrylate esters and modifying copolymerizable monomars are ultraviolet radiation polymerized to form the acrylate copolymer. The PSAs made by the disclosed process are improved over those made by solution polymerization but are still not 35 completely adequate for some uses such as adhesion at high and low temperature extremes.

wo g~J20751 ~? ~3~ PCT/US92/~120 Silicone PSAs exhibit the flexibility of silicone rubber and the high temperature stability of silicone resin, thereby providing useful service temperatures ranging between -70C and 250C. Their 5 excellent electrical properties and chemical inertness are noteworthy attributes making them suitable for use in the plating and electronics industry. Silicone PSAs bond to a wide variety of substrates including surfaces having high or low surface energies; e.g., glass, lO paper, polyolefins, polytetrafluoroethylene, fluorohalocarbon films, and silicone release liners.
Most acrylic PSAs will not bond, or adhere poorly, to many of these low energy surfaces, while silicone PSAs are effective bonding agents for these materials.
15 Silicone PSAs, due to their biocompatibility, are widely used in transdermal drug delivery systems and also as general medical adhesives.
Silicone PSAs, however, have a number of disadvantages including the following. First, silicone 20 PSAs are expensive. Second, most silicone PSAs are solvent-based, which limits the thickness at which they may be coated. Third, silicone PSAs are slow to cure due to the need for a solvent removal step prior to crosslinking at temperatures in axcess of 130C. In 25 addition, silicone PSAs generally have low tack and limited adhesion build. -Combining silicone PSAs and acrylate PSAs to achieve specific properties has been attempted.
JP 62-2~5982 ~Murachi) describes an automotive 30 protective molding having a pressure-sensitive adhesive made by combining a silicone pressure-sensitive adhesive and an acrylate pressure-sensitive adhesive with a polyurethane or polyisocyanate crosslinker. The PSAs are solvent based. The problem addressed by the 35 publication is to obtain a pressure-sensitive adhesive that has high shear strength to resist separation of the adhesive from the molding because of expansion and ~ contraction of the molding due to changes in :;

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WO92/20751 PCT/US92/~120 2 ~ 0 3 ~

temperatures. Disadvantages of this adhesive system are a limited pot life in coating the adhesive because of the crosslinker, shelf stability of the coated product which may be affected by the crosslinker, and 5 the need to dry off large amounts of organic solvent since the silicone and acrylic pressure-sensitive adhesives are initially 40% and 37% solids, respectively, and are further diluted with solvent as shown in the examples.
U.S. Patent No. 4,7gl,16~ (Traver) describes an emulsion pressure-sensitive adhesi~e comprising from 50 to 99% of an organic pressure-sensitive adhesive and from 1 to 50% of a silicone pressure-sensitive adhesive. The solvent based silicone 15 pressure-sensitive adhesive in solvent is emulsified and the resulting emulsion is added to an acrylic emulsion pressure-sensitive adhesive, thereby providing an emulsified composition, however, said composition , contains significant levels of solvent introduced via 20 the silicone PSA. Careful control of the emulsifying agent and the drying conditions is required to prevent phase separation of the emulsion during the drying step. Again, large amounts of energy are required to dry the emulsion to a pressure-sensitive adhesive.
European Patent Publication No. 28992~ ~General Electric), published November 9, 1988, describes an emulsion or solution comprising: (a) 100 parts by weight of water or organic solvent; (b) from about 10 to about 400 parts by weight o~ pressure-sensitive 30 adhesive comprising: (i) from about 50 to about 99% by weight organic pressure-sensitive adhesive; and (ii) from 1 ts about 50% by weight of silicone pressure-sensitive adhesive; and (c~ an effective amount of organic peroxide or alkoxy silane 35 cross-linking agent to increase the shear strength of the composite adhesive through crosslinking of the silicone. The emulsion generally re~uires the use of an emulsifying agent or agents to maintain both the ~092/20751 PCT/US92/~120 3 ~

micelles of silicone adhesive and micelles of organic adhesive in a substantially stable state of suspension even at low water content, so that drying may be accomplished prior to gross phase separation of the s silicone adhesive and the organic adhesive.
JP 61-57355 discloses solvent based adhesives having a silicone pressure-sensitive adhesive, an acrylate pressure-sensitive adhesive, and an organic peroxide crosslinking agent to prevent phase 10 separation. This publication discloses that isocyanate crosslinkers are not desirable because it does not prevent phase separation of the acrylic and silicone PSA's. The examples show that the PSA needs to be cured at 150C for 3 minutes.
JP 63-291971 discloses solvent based adhesives that are a mixture of silicone pressure-sensitive adhesive, acrylate pressure-sensitive adhesive, a bridging agent, and a "silicone macromonomer". The adhesives disclosed in this publication have poor shear 20 strength without the "silicone macromonomer." This publication also states that adhesives made as diæclosed in JP 61-573S5 have poor adhesion. ~
A need thus exists for a PSA system which has the advantages of both acrylate PSAs and silicone PSAs 25 which requires little or no solvent, thereby reducing or eliminating the environmental and health hazards associated with solvent use, as well as the need f or drying. A need also exists for such a PSA system which i5 curable by an energy efficient means such as 30 radiation and which, unlike most known silicone acrylate systems, is not prone to gross phase separation problems. A need also exists for a silicone/acrylic PSA system which possesses balanced PSA properties tailorabla over a wide range, thereby 35 providing greater flexibility than known systems in achieving substrate-specific adhesion.

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W092/207~1 PCT/U~92/~120 21 (~3~

The inventors of the present invention have discovered an adhesive composition having excellent adhesion to a broad range of substrates over a broad temperature range. The adhesive composition is 5 virtually solvent-free and can be efficiently cured by exposure at ambient temperatures to a number of radiation sources including those capable of emitting ultraviolet radiation, electron beam radiation, actinic radiation, and gamma radiation. Preferably, the 10 adhesive compositions is cured via ultraviolet radiation. Ultraviolet radiation can be provided by various sources having emission spectra b~twean about 250 to about 400 nanometers depending upon the initiators and crosslinkers that are used.
The adhesive compositions of the invention are useful in making pressure-sensitive adhesive transfer tapes or coated adhesive tapes.
The adhesives of the invention exhibit excellent adhesion to the new paints in use in the automobile 20 industry as well as superior resistance to detachment at low temperatures as compared to known acrylic adhesi~es.
The adhesives of the invention exhibit utility in the attachment of body side molding, decorative 25 trim, weatherstripping, and the lika, to automobile surfa~es painted with the new paints that are in use in the automotive industry. These new paints are formulated for environmental conservation, enhanced appearance, and durability, such as resistance to 30 degradation from common sources of contamination such as acid rain. The changes in the paint formulations have increased the dif f iculty with which known acrylate pressure-sensitive adhesives can adhere to substrates coated with such paints. The automobile industry 35 requires that the adhesive, or a tape made with the adhesive, have good adhesion to the paint surf ace and the molding, and resist detachment at WO92/20751 PCT/US9~/~120 2 J 0~)37i~

temperatures as low as -40C. The adhesives of the present invention meet these stringent requirements of the automotive industry.
The adhesives of the invention also show great 5 utility in medical applications because the adhesion build on human skin is sufficient but not excessive, thus facilitating the removal of a bandage coated with the adhesi~e from human skin.

Summary of the Invention The present invention provides a radiation curable pressure-sensitive adhesive composition comprising:
(a) from about 5 parts to about 95 parts of 15 acrylic monomer wherein the acrylic monomer comprises:
(i) from about 50 to about lO0 parts of alkyl acrylate monomer, the alkyl groups of which have an average of 4 to 12 carbon atoms; and (ii) correspondingly from about 50 parts to 20 about 0 parts of monoethylenically unsaturated copolymerizable modifier monomer;
wherein the amounts of (i) and (ii) are selected such that the total amount of (i) plus (ii) equals lO0 parts by weight of the acrylic monomer; and (b) correspondingly from ~bout 95 parts to about 5 parts of a silicone pressure-sensitive adhesive wherein the amounts of (a) and (b) are selected such that the total amount of (a) plus (b) equals lO0 parts by weight;
(c) about 0 part to about 5 parts by weight of photoinitiator based upon lO0 parts by weight of the acrylic monomer; and (d) about 0 to about 5 parts by weight of a crosslinker based upon lO0 parts by weight of (a) plus 3s (b)-Preferably, the adhesive composition comprisesabout O.Ol to about 5 parts by weight of photoinitiator based upon lO0 parts by weight acrylic monomer.

WO92/207~1 PCT/US92/04120 2103~9 Preferably, the adhesive composition comprises about 0.0l to about 5 parts by weight of crosslinker based upon l00 parts by weight acrylic monomer.
The silicone pressure-sensitive adhesive 5 preferably comprises the intercondensation product of a silanol functional polydiorganosiloxane a~d a silanol functional copolymeric silicone resin.
The pressure-sensitive adhesive composition of the invention is a solventless system (i.e., containing l0 preferably no organic or inorganic solvents, at most less than about l weight percent of solvent based upon the total weight of the pressure-sensitive adhesive composition).
Preferably, the a~hesive composition consists lS essentially of acrylic monomer, silicone pressure-sensitive adhesive, optional photoinitiator and optional crosslinker.
The invention also provides pressure-sensitive~
adhesive tapes comprising the adhesive of the invention 20 coated on a backing or substrate~ or as a transfer tape.
One preferred embodiment provides pressure-sensitive adhesive tap~s exhibiting both improved adhesion to automotive paints and resistance 25 to detaching at low temperature without loss of other critical properties.
Preferred pressure-sensitive adhesive tapes of the invention for adherence to paint compris ~he pressure-sensitive adhesive of the invention coated on 30 a ~ubstrate. In a highly preferred embodiment, the substrate comprises a foam layer comprising an ultraviolet-radiation polymerized acrylic copolymer of monomers comprising from about 80 parts to about 99 parts by weight of alkyl acrylate monomer, the alkyl 35 groups of which have an average of 4 to ~2 carbon atoms, and correspondingly, from about 20 parts to about l part by weight of monoethylenically unsaturated polar copolymerizable monomer; wherein the total amount WO92/20751 PCT/USg2/~120 3~3~ 8 of alkyl acrylate monomer plus polar copolymerizable monomer incorporated into the copolymer equals lO0 parts by weight.
Another preferred embodiment provides 5 pressure-sensitive adhesive tapes which are useful in medical applications in that they adhere to skin but do not exhibit excessive adhesion build over time which would result in a difficult, and thus painful, removal.

Detailed Description of the Invention The present invention relates to an ultraviolet radiation polymerizable pressure-sensitive adhesive composition comprising from about 5 to about 95 parts by weight of acrylic monomer and correspondingly from 15 about 95 to about 5 parts by weight of silicone pressure-sensitive adhesive (PSA). Preferably, the adh~sive composition comprises from about lO to about 90 parts acrylic monomer and from about 90 to about l~
parts silicone PS~ for ease of handling. More 20 preferably, the adhesive composition comprises from about 20 to about 80 parts acrylic monomer and from about 80 to about 20 parts silicone PSA for even greater ease of handling. Most preferably, the adhesive composition comprises from about 30 to about 25 70 parts acrylic monomer and from about 70 to about 30 parts silicone PSA for the greatest ease of handling.
The adhesive of the invention has a good balance of adhesi~e properties including good tack, good adhesion build, and good peel adhesion. The adhesive adheres 30 well to a variety of different surfaces over a broad range of temperatures and therefor has a broad range of ! utility for a broad range of applications.
For adhesion to the newer automotive paints, the adhesive composition comprises from about 25 to about 35 75 parts acrylic monomer and from about 75 to about 25 parts silicone PSA for good peel adhesion, preferably from about 4Q to about 60 parts acrylic monomer and from about 60 to about 40 parts silicone PSA for good ;::
:

WO92/20751 PCT/U~g2/~120 9 21~33~9 peel adhesion and good resistance to detachment of the molding from the painted surface at low temperatures, and most preferably from about 55 to about 45 parts acrylic monomer and from about 45 to about 55 parts 5 silicone PSA for superior peel adhesion and superior performance at low temperatures.
For medical applications, the adhesive composition comprises from about 25 to about 75 parts acrylic monomer and from about 75 to about 25 parts 10 silicone PSA for providing good adhesion while limiting excessive adhesion build, preferably about 40 to atout 60 parts acrylic monomer and about 60 to about 40 ~arts silicone PSA for reasons of providing good adhesion while limiting even more excessive adhesion build.
The acrylic monomers useful in the invention comprise from about 50 to about 100 parts alkyl acrylate monomer and from about 50 to about 0 parts of monoethylenically unsaturated copolymerizable modifie~
monomer for a good balance of adhesive properties (i.e., typically about 0.1 to about 50 parts of modifier monomer is used, ~ypically about 2 to about 30 parts modifier monomer if polar monomer is used, about 5 to about 50 parts modifier monomer if non-polar monomer is used); preferably from about 60 to about 95 25 parts alkyl acrylate monomer and from about 40 to about 5 parts modifier monomer for supexior balance of adhesive properties (i.e., typically a~out 5 to about 20 parts modifier monomer if polar monomer is used, about 5 to about 40 parts modifier monomer if non-polar 30 monomér is used); and most preferably from about 80 to about 95 parts alkyl acrylate monomer and from about 20 to about 5 parts modifier monomer for the best balance of adhesive properties.
The ranges listed for polar modifier monomer and 35 non-polar modifier monomer are approximate and can vary depending upon the particular monomer selected.

WO92/20751 PCT/US92/~120 For paint applications, the acrylic monomers useful in the invention comprise from about 60 to about 98 parts alkyl acrylate monomer and about 40 to about 2 parts of copolymerizable modifier monomer, preferably 5 polar modifier monomer for reasons of providing good peel adhesion to paint; preferably about 70 to about 95 parts alkyl acrylate monomer and about 30 to about 5 parts polar modifier monomer for providing adhesion build to paint; and most preferably about 75 to about 10 85 parts alkyl acrylate monomer and about 25 to about 15 parts polar modifier monomer for providing the best adhesion build to the paint as well as good resistance to detachment at low temperatures.
For medical applications, the acrylic monomer 15 comprises from about 50 to about 100 parts alkyl acrylate monomer and about 50 to about 0 parts modifier monomer for reasons of providing adequate adhesion to skin while limiting excessive adhesion build to skin , (i.e., typically about 2 to about 20 parts polar 20 modifier monomer if polar modifier monomer is used, about 0 to about 50 parts non-polar modifier monomer if non-polar modifier monomer is used); preferably about 70 to about lO0 parts alkyl acrylate monomer and about 30 to about 0 parts modifier monomer for reasons of 25 providing good adhesion to skin while limiting even more excessive adhesion build to skin (i.e., typically about 2 to about about 15 parts polar modifier monomer if polar modifier monomer is used, about 0 to about 30 parts non-polar modifier monomer if non-polar modifier 30 monomer is used); and most preferably about 80 to about lO0 parts alkyl acrylate monomer and about 20 to about O parts modifier monomer (i.e., typically about 10 to about 2 parts polar monomer if polar modifier monomer is use~, about 0 to about 20 parts non-polar monomer if 35 non-polar modifier monomer is used) for reasons of providing good adhesion to skin while limiting to the greatest extent excessive adhesion build to skin.

WO92/20751 PCT/US92~04120 ~1 033~

The alkyl acrylate monomer useful in the adhesive composition of the present invention is preferably a monofunctional unsaturated acrylate ester(s) of a non-tertiary alkyl alcohol, the molecules 5 of which have from about 4 to about 14 carbon atoms.
Such monomers include those selected from the group consisting of isooctyl acrylate, 2-ethyl hexyl acrylate, isononyl acrylate, decyl acrylate, dodecyl acrylate, butyl acrylate, hexyl acrylate, mixtures 10 thereof, and the like. Preferred alkyl acrylate monomers comprise isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, butyl acrylate, and mixtures thereof. The alkyl acrylate monomers can be copolymerized with at least one copolymerizable 15 modifier monomer.
The term "monoethylenically unsaturated copolymerizable modifier monomer", also referred to herein as the "modifier monomer" refers to a monomer .
that is capable of increasing the Tg (glass transition 20 temperature) of a copolymer formed from the acrylic monomer, i.e., the alkyl acrylate and the modifier monomer, so that the Tg of the copolymer would be higher than that of a homopolymer of the alkyl acrylate by itself. The modifier monomer is selected from 25 monoethylenically unsaturated copolymeriæable monomers wherein the homopolymer of the modifier monomer has a~
higher Tg than the homopolymer of the alkyl acrylate.
For example, the Tg of a homopolymer of 2-ethylhexyl acrylate is -50~. Examples of suitable comonomers are 30 acrylic acid (homopolymer Tg of 106C~ and isobornyl acrylate (homopolymer Tg of 94C). The modifier ! monomer can comprise polar monomer, non-polar monomer, or mixtures thereof. Useful polar monomers include acrylamides, substituted acrylamides, acrylic acid, 35 N-vinyl caprolactam, hydroxyalkyl acrylates such as 2-hydroxy ethyl acrylate; N-vinylpyrrolidone, N,N-dimethylacrylamide, acrylonitrile, methacrylic acid, itaconic acid, mixtures thereof, and the like.

W O 92/20751 PC~r/US92/04120 ,l ~Q~3 3~
~ - 12 -Preferred, polar monomers comprise acrylic acid acrylamide, N-vinyl-2-pyrrolidone, N-vinyl caprolactam, 2-hydroxyethylacrylate, and mixtures thereof for reasons of providing good adhesion properties including 5 good adhesion build. Non-polar monomers that are useful, include cyclohexyl acrylate, trimethylcyclohexyl acrylate, dicyclohexadienyl acrylate, isobornyl acrylate, methylacrylate, ethyl acrylate, derivatives thereof, mixtures thereof, and 10 the like.
The amount of modifier monomer that is useful depends upon the particular modifier monomer, alkyl acrylate, and silicone PSA in the composition. The components of the composition, i.e., the modifier 15 monomer, the alkyl acrylate monomer, and the silicone PSA, are selected such that when the silicone PSA has been dispersed into the monomers to form a homogenous mixture, the components will not exhibit phase separation when left at room temperature, i.e., about 20 2~C, over a period of 12 hours, as visible to the naked eye. Phase separation, which is believed to be caused by incompatibility of the components, can appear as a distinct layer wherein the monomers exist as layers or as a small pool in the silicone PSA, 25 depending upon the concentration and particular type of modifier momomer, alkyl acrylate, and monomers to silicone PSA in the composition. Phase separation can also be noted as extreme clouding of the PSA
composition wherein the PSA could appear as curd-like 30 particles in the monomer. There are variations of the phenomena described above as phase separation, but one skilled in the art would readily recognize phase separation by visual inspection.
The listed alkyl acrylate and modifier monomers 35 are useful for all applications.
For paint applications, monomers which provide particularly good properties in addition to being commercially available are alkyl acrylate monomers :

WO92/20751 2 I ~ 3 3 .5 q selected from the group consisting of 2-ethyl hexyl acrylate, isooctyl acrylate, butyl acrylate and mixtures thereof, and the modifier monomer acrylic acid.
For medical applications, monomers which provide particularly good properties in addition to being commercially available are modifier monomers selected from the group consisting of 2-ethyl hexyl acrylate, isooctyl acrylate, and mixtures thereof, and modifier 10 monomer selected from the group consisting of acrylic acid, isobornyl acrylate, and mixtures thereof.
Silicone pressure-sensitive adhesi~es employed in the adhesive composition of the invention, are well known in the art. Silicone PSAs are, in general te:rms, 15 blends of (i) polydiorganosiloxanes (also referred to as "silicone gums" typically having a number average molecular weight of about 5000 to about 10,000,000 preferably about 50,000 to about 1,000,000) with (ii) copolymeric silicone resins (also referred to as 20 an "MQ resin" typicaily having a number average molecular weight of about 100 to about 1,000,000, preferably about 500 to about 50,000 number average molecular weight) comprising triorganosiloxy units and SiO4n units. It is beneficial, in terms of improving 25 PSA properties, to provide a chemical means of reacting the copolymeric silicone resin with the polydiorganosilGxane. To achieve such a reaction, two different reaotion chemistries have been commonly used;
cond~nsation chemistry and addition-cure chemis~ry.
Silicone PSAs based on condensation chemistry can be prepared by admixing silanol functional copolymeric resins comprising trîorganosiloxy units and sio4n units with silanol-endblocked polydiorganosiloxanes as shown in U.S. Patent Nos.
35 2,73~,721; 2,814,601; 4,309,520; 2,857,356; 3,S28,940;
and Great Britain Patent No. 998,232. Such blends, which are usually a solvent solution of copolymeric silicone resin and polydiorganosiloxane, as used in the WO92/20751 PCT/US92/~120 ~33- - 14 -art, are generally applied to a backing, heated to remove solvent, and crosslinked, if necessary, to improve the physical properties of the PSA. It is taught in these references that improvements in PSA
s properties are realized when the copolymeric silicone resin and the polydiorganosiloxane are intercondensed, providing intra- and inter-condensation within the adhesive~ According to these references the condensation between the copolymeric silicone resin and lO the polydiorganosiloxane can be effected either in the presence of catalyst at ambient or elevated temperature, or in the absence of catalyst at elevated temperatures, as well as prior to application of the PSA to a backing, or subsequent to application of the 15 PSA to a backing. Effective catalysts for promoting the silanol condensation reaction include organometallic compounds and metal salts of carboxylic acids as taught in U.S. Patent No. 2,736,721, and amines as taught in Canadian Patent No. 575,664. An 20 additional method of intercondensing silicone resins and polydiorganosiloxanes is through the addition of orthosilicates, as taught in U.S. Patent No. 4,831,070, and polysilicates.
. A silicone PSA comprising the intercondènsation 25 product of a silanol functional polydiorganosiloxane and a silanol functional copolymeric silicone resin, as discussed above, can optionally include a free radical polymerization catalyst, such as a diaryl peroxide crosslinker, to crosslink the adhesive composition, 30 thereby improving the high temperature shear properties of the PSA with only a slight loss in peel adhesion as taught in The Handbook of Pressure-Sensitive Ad~hesive Technoloqy, (Satas, 1982), p. 348.
The polydiorganosiloxanes used in the 35 preparation of the silicone PSA component of the instant invention can include any of the common structures and accompanying functionalities known.in the art, including polydimethylsiloxane polymers and W092/20751 PCr/US92/04~20 21 033~.~

poly(dimethylsiloxane/diphenylsiloxane) copolymers.
Preferably, for automotive applications, polydimethylsiloxane is used in the preparation of the silicone PSA component for superior adhesion.
The copolymeric silicone resins useful in the preparation of the silicone PSA component of the present invention include any of the common structures recited in the above references which include copolymeric silicone resins having one or more of the 10 following functionalities: silicon-bonded hydrogen, silicon-bonded alkenyl, and silanol. Other useful silicone resins include three component terpolymers comprising R3Sio~n, sio4n, and R2Sio~ structural units, (MQD resins~ wherein R is selected from the group 15 consisting of alkyl radicals comprising l to 3 carbon atoms and phenyl radical, and wherein the ratio of R3Sioln units to sio2 is between about 0.6 and about 0.9 inclusive as taught in U.S. Patent No. 2,736,721 and those taught in Kokai HEI 2-36234, which comprise ~0 R3Sio1n, SiO4n, and RSl03~ structural units (MQT resins).
Many modifications of silicone PSAs have been ~^ suggested in the literature. Such modifications include simplifying or improving methods of preparation, improving shelf life by stabilizing PS~
25 solution viscosity over time, and improving the balance of adhesive properties (tack, peel, and shear~
possessed by such PSAs. Preparation method improvements are taught in U.S. Patent No. 4,g43,620, where ammonia water is used in place of conventional 30 c~ustic catalysts to effect the condensation reaction between the polydiorganosiloxane and resin, thereby ! providing an adhesive of consistent quality having greatly improved stability against viscosity changes.
Additional methods of improving the viscosity stability 35 of silicone PSAs include addition of isopropanol, as taught in U.S. Patent No. 4,309,520, as well as process modifications in combination with triorganosiloxy endblocking radicals, as taught in U.S. Patent Nos.

W092/207SI PCT/US92/~120 3 ~ :

4,584,355; 4,585,836; and 4,584,394; which provide silicone PSAs having improved viscosity stability, film physical property stability upon aging, and lap shear stability.
Silicone PSAs prepared according to any of the aforementioned references are suitable for use in the instant invention, however, it is preferred that silicone PSAs used in the instant invention be intercondensed prior to their introduction into the 10 acrylic monomer component.
Silicone PSAs prepared by addition-cure chemistry generally comprise polydiorganosiloxanes having alkenyl groups, copolymeric silicone resins comprising Sio4~ and R3Sioln structural uni~s wherein R
15 is as defined previously having one or more of the following functionalities: silicone-bonded hydrogen, silicone bonded alkenyl groups such as those selected from the group consisting of vinyl, allyl, and propenyl; or silanol, optionally a crosslinking or 20 chain extending agent, and Pt or other noble metal hydrosilation catalyst to effect the curing of the silicone PSA. Examples of such compositions are found in U.S. Patent Nos. 3,527,842; 3,983,298; 4,774,297;
European Patent Publication Nos. 355,991, and 393,426, 25 and Kokai HEI 2-58587. Reported advantages of addition-cured silicone PSAs include reduced viscosity as compared to silicone PSAs prepared via condensation chemistry, higher solids content, stable viscosity with respect to time, and lower temperature cure.
A wide range of commercially available silicone PSAs are well suited for use as the silicone PSA
component of the present invention. Examples of such silicone PSAs include but are not limited to Dow Corning's 280A, 282, Q2-7406, and Q2-7566; General 35 Electric's PSA 590, PSA 600, PSA 595, PSA 610, PSA 518 (medium phenyl content), PSA 6574 (high phenyl content~, and PSA 529; Shin-Etsu's KR-lOOP, KR-100, KR-101-10, and X-40-820, and Rhone-Poulenc's Rhodorsil WO92/207~1 PCT/US92/04120 - 17 _ 21 03~
353, 354, 356, and 395 (dimethyl/diphenyl gum). Also useful as the silicone PSA component in the present invention are various blends of silicone PSAs, such as blends of two different dimethylsiloxane-based PSAs, as 5 taught in The Handbook of Pressure-Sensitive Adhesive Technoloq~ (5atas, 1982), p. 346, or blends of dimethylsiloxane-based PSAs with dimethylsiloxane/diphenylsiloxane-based PSAs a~s shown in U S. patent No. 4,g25,671.
The adhesive composition of the invention comprises acrylic monomer(s), a silicone PSA, optional photoinitiator, and optional crosslinker. The photoinitiator when irradiated with ultraviolet (UV) radiation initiates polymerization of the acrylic 15 monomers. Photoinitiators which are useful include the benzoin ethers such as benzoin methyl ether or benzoin isopropyl ether, substituted benzoin ethers such as anisoin methyl ether, substituted acetophenones such ~s 2,2-diethoxyacetophenone and 20 2,2-dimethoxy-2-phenylacetophenone, substituted alpha-ketols such as 2-methyl-2-hydroxypropiophenone, aromatic sulfonyl chlorides such as 2-naphthalene sulfonyl chloride, and photoactive oximes such as 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)-oxime.
25 The photoinitiator if used is typically present in an amount of about 0.01 to about 5 parts, preferably about 0.01 to about ~ parts, per one hundred parts of acrylic monomer (i.e., alkyl acrylate monomer plus copolymerizable modifier comonomer). We theorize that 30 after polymerization, initiator by-products may be present in the PSA as well as some unreacted photoinitiator depending on the total initiator amount used.
The adhesive composition of the invention may 35 also contain a crosslinking agent, preferably a photoactive crosslinking agent, most preferably a W
photoactive crosslinking agent. The photoinitiator can also be the crosslinking agent. The terms WO92/20751 PCT/US92/~120 ~3~ - 18 -"crosslinking agent" and ~'crosslinker" are used interchangeably herein. Various types of crosslinking agents are useful in the practice of the invention.
The cured adhesive composition of the present invention 5 has at least a first phase and a second phase. The first phase consists primarily of the silicone PSA and the second phase consists primarily of acrylic copolymer. The acrylic phase or silicone phase or both the acrylic phase and silicone phase may be continuous.
10 Certain crosslinkers are capable of crosslinking within the acrylic phase (useful when the acrylic phase ic continuous~. Certain crosslinkers are capable of crosslinking within the silicone phase (ussful when the silicone phase is continuous). Other crosslinkers are 15 capable of crosslinking within each individual phase as well as between the two phases (useful when either or both phases are continuous). Preferably, the crosslinker is selected from the group consisting of multifunctional acrylates, triazines, silane coupling 20 agents, benzophenones, and mixtures and derivatives thereof.
One type of crosslinker is a multifunctional acrylate such as 1,6-hexanediol diacrylate as well as those disclosed in U.S. Patent No. 4,379,201 (Hèilmann 25 et al.), (such as trimethylolpropane triacrylate, pentaerythritol tetracrylate, 1,2-ethylene glycol diacrylate, etc.) These crosslinkers are useful in crosslinking the acrylic phase to improve the internal strength of the acrylic phase when the acrylic phase is 30 continuous.
The substituted triazines, discussed above include those disclosed in U.S. Patent Nos. 4,329,384 and 4,330,590, e.g., 2,4-bis(trichloromethyl)-6-p-methoxystyrene-s-triazine. We theorize that the 35 tria~ines crosslink within each individual phase as well as between the two phases. As discussed above silane coupling agents are also useful in crosslinking.
~ Useful silane coupling agents are epoxy type :

21 ~3~Y

crosslinkers such as gamma-glycidoxypropyl trimethoxysilane, methacryl type such as gamma-methacryloxypropyltrimethoxysilane, and mercapto type such as gamma-mercaptopropyltrimethoxy silane. As s discussed above benzophenone crosslinkers can also be used in the practice of the invention. Crosslinkers are preferably used for applications in which a high shear strength is desired. When used, the crosslinking agent is typically present in an amount of from about 10 0.01 to about 5 parts by weight per one hundred parts total of acrylic monomer plus silicone PSA.
The adhesive of the invention i5 typically prepared by the following method. A silicone pressure-sensitive adhesive composition is stripped of 15 its solvent to remove substantially all of the organic solvent in the PSA composition. The solvent can be stripped off and recovered by methods known in the industry. The resulting silicone PSA is dispersed or~
dissolved in alkyl acrylate monomer and copolymerizable 20 modifier monomer, foilowing which photoinitiator is added to form the pressure-sensitive adhesive composition of the invention. The silicone PSA can also be dispersed or dissolved first in the acrylate monomer before adding th~ copolymerizable modifier 25 monomer, etc. Optional crosslinking agents or other additives such as antioxidants and fillers may also be incorporated into the adhesive composition. The adhesive composition can then be coated onto a suitable substrate and exposed to ultraviolet radiation to 30 obtain a pressure-sensitive adhesive.
The viscosity of the adhesive composition can be adjusted, by modifying the adhesive composition, to obtain a viscosity appropriate for the coating method to be used. For good coatability, the adhesive 35 composition of the invention typically has a viscosity of about 500 to about 40,000 cps. Conventional coating methods such as knife coating and roll coating can be WO92/20751 PCT/US92/~120 ?.~ 20 -used. At higher viscosities (i.e. above about 40,000 cps) the adhesive composition can be extruded or die coated.
The adhesive composition of the invention can be 5 coated onto a flexible carrier web and polymerized in an inert, i.e., a substantîally oxygen-free atmosphere or a nitrogen atmosphere. A sufficiently inert atmosphere can be achieved by covering a layer of the photoactive coating with a plastic film which is lO substantially transparent to ultraviolet radiation, and irradiating through that film in air using fluorescent-type ultraviolet lamps. If, instead of covering the polymerizable coating, the photopolymerization is to be carried out in an inert 15 atmosphere, the permissible oxygen content of the inert atmosphere can be increased by mixing into the polymerizable monomer an oxidizable tin compound as taught in U~S. Patent No. 4,303,485 (Levens), which also teaches that such procedures will allow thick 20 coatings to be polymerized in air.
The adhesive composition of the invention is typically cured and applied by first making a tape construction which comprises a layer of adhesive composition evenly coated between two liners at least 25 one of which is coated with a release material. A
transfer tape can be made by coating the adhesive composition between two liners both of which are coated with a release coating. The release liners typically comprise a clear polymeric material such as polyester 30 that is transparent to ultraviolet radiation.
Preferably, each release liner is first coated or primed with a release material which is incompatible with the silicone containing adhesive of the invention.
For example, silicone release liners can be used for 35 adhesive compositions containing high amounts of acrylic monomer compared to silicone PSA, e.g., 90 parts acrylic monomer, lO parts silicone PSA. Adhesive compositions with higher concentrations of silicone PSA

WO92/20751 PCT/~S92J~120 - 21 _ 2 1 03 ~ 5 g can ~e coated onto release liners coated with other release compositions such as those comprising polyfluoropolyether or fluorosilicone. Adhesive compositions containing phenyl silicone PSAs can be s coated onto liners coated with a methyl silicone release composition.
The release liners useful in the practice of this invention are those that are suitable for use with silicone pressure-sensitive adhesives and organic 10 pressure-sensitive adhesives. Examples of useful compositions are compositions containing from about 15 to about 90% by weight of crosslinkable polyfluoropolyether, and from about 10 to about 85% by weight of inert polyfluoropolyether oil described in 15 copending U.S. Application Serial No. 07/450,623.
Suitable cross-linkable polyfluoropolyethers are represented by the general formula:
Zo{~cF2lFot~ lFoti (CF2lFOtb~ cF2o~g}
oR2 oR2 R~
wherein Z represents a terminal group that either ~: contains a functional moiety that can enter into an ~ ~ 25 addition or condensation reaction to form a polymer or :~ an inert moiety incapable of entering into a reaction to form a polymer;
Z' represents a terminal group that contains a functional moiety that can enter into an addition or 30 condensation reaction to form a polymer;
each Rl independently represents a fluorine or a perfluoroalkyl group that can be linear, branched, or ~! cyclic;
each oR2 independently represents a 35 perfluoroalkoxy group wherein R2 represents a perfluoroalkyl group or a perfluoroalkyl group substituted with one or more ether oxygen atoms, independently selected from the units having the ' .

:-, WO92/20751 PCT/US92/~120 ~9 - 22 -structure -(R30~-R4, in which each R3 is independently selected from -CF2, -CF2CF2-, and -CIF2CF-and R4 represents a perfluoralkyl group selected from linear, branched, and cyclic groups, f is zero or a number having a value of 1 to 6, g is a number representing the average number of 10 ~CF20~ units randomly distributed within the chain andhas a value of zero or greater, h is a number representing the average number of ~CF2IFOt Rl units randomly distributed along the chain and has value of 1 or greater;
i and i' can be the same or different and each 20 is a number representing the number of -(ICFO)- and oR2 *CF2CFOt units, respectively, distributed within the o~2 chain, the sum of i and i' having a value of 0 or greater and the ratio i/i' being 0 to 5 î
the ratio of g/h being less than 10;
the ratio of (i+i')/(g+h) being 0.0 to 1.5; and the number average molecular waight of the polyfluoropolyether being from about 650 to 20,000.
Especially useful polyfluoropolyether polymers 35 are those having non-perfluorinated, crosslinkable end ~roups such as acrylate, isocyanato, or bis(amidopropyltriethoxysilane).
The general formula for inert polyfluoropolyether oils are represented by the general 40 formula:
XF2jCjO{~CF2~0~1 ~CF2CIFO~ FO~j ~CF2CIFOth ~CF20~g}CjF2jX
oR2 oR2 R

WO92/207sl PCT/US92/~120 - 23 - 21033~9 wherein each X independently represents hydrogen or halogen, provided that when X represents hydrogen, then j is 1 or 2, and when X represents halogen, then j is 5 an integer from 1 to 5;
Rl, oR2~ R3, R4, f, g, h, i, i', are as defined previously;
k represents 3 or 4; and 1 represents 1 or a number greater than 1.
Examples of inert polyfluoropolyether fluids useful in the practice of this invention include those designated by the trade names "Krytox" 1506, "Krytox"
1514, "Krytox" 1645 r commercially available from E.I.
DuPont de Nemours and Company, "Denmum" fluids, 15 commercially available from Daikin, and "Fomblin" Y and "Fomblin" Z fluids, commercially available from Montecatini-Edison.
Release liners and compositions are also commercially available. Useful commercially available 20 release coatings inciude Dow Corning~ Syl-off~ 7610 polydimethylsiloxane release coating, and Q2-7785 fluorosilicone release coating; Shin-Etsu X-70-029NS
fluorosilicone release coatin~s; and the like.
The adhesive compositions of the invention can 25 also be coated onto a differential release liner, i.e., a release liner having a first release coating coated on one side of the liner and a second release coating coated on the opposite side of the liner. The two release coatings should have different release values.
30 For example, one release coating may have a release value of 5 grams/cm, i.e., 5 grams of force is needed ! . to remove a strip of adhesive 1 cm wide from the coating, and the sPcond release coating may have a release value of 15 grams/cm.
The adhesive is typically coated onto the side of the release liner coated with the release coating having the higher release value and the resulting tape can be wound into a roll. As the tape is unwound, the WO92/207SI ~'~ ~ PCT/US92/04120 adhesive remains adhered to the release coating with the higher release value. After the tape is applied to a substrate, the release liner can be removed to expose an adhesive surface for further use.
The adhesive composition is cured by exposure to ultraviolet radiation which is transmitted through the release liner(s). When a transfer tape is made, one of the liners of the transfer tape can be removed and the exposed adhesive surface can be laminated to another 10 substrate such as a backing. The remaining release liner aids in transferring the adhesive to the substrate. The substrate can be any of the typical substrates used for tapes such as those selected from the group consisting of polymeric films ~e.g.
15 polyester, polypropylene, polyurethane) metal foils, glass cloth, paper, cloth, nonwoven materials, foam sheets, and the like. Foam sheets are known in the industry and include open and closed cell foams made from polyethylene, polyurethane, acrylates, 20 polystyrene, neoprene, silicone, and the like.
The adhesives of the invention adhere well to polyester, polycarbonate, polyolefins such as polyethylene, and polypropylene which are known to be difficult materials to adhere to.
Photopolymerization of the adhesive compositions of the invention by exposure to ultraviolet radiation yields phase- eparated pressure-sen~itive adhesives.
The cured adhesive composition of the present invention has at least a first phase and a second phase. The 30 first phase consists primarily of the silicone PSA and the second phase consists primarily of acrylic copolymer. Factors influencing the morphology i.e., which phase of the cured adhesive composition is continuous and which phase is discontinuous, include 35 the ratio of acrylic monomer to silicone PSA, the particular polar copolymerizable monomer used, and the ratio of alkyl acrylate monomer to polar copolymexizable monomer used.

- 25 - 21~3~
For example, adhesive compositions containing lower concentrations of silicone PSA; i.e., having a higher ratio of acrylic monomer to silicone PSA, favor the formation of a continuous acrylic phase having a 5 silicone phase dispersed therein. Conversely, adhesive compositions containing higher concentrations of silicone PSA favor the formation of a continuous silicone phase having an acrylic phase dispersed therein. The concentration and polarity of the lO components of this system can be varied widely to obtain the PSA properties desired for a particular application. Either phase can be continuous, with the other phase being discontinuous, depending upon the particular adhesive composition. Alternatively, both 15 phases can be continuous.
In one preferred embodiment, for adhesion to automotive paints, the silicone phase is the continuous phase and the acrylic phase exists as relatively uniform inclusions ranging in size from about O.l 20 micrometer to about i micrometer when examined by transmission electron microscopy (TEM). A
pressure-sensitive adhesive tape having such an adhesive layer provides substantial improvement in adh,esion and adhesion build to auto body paint surfaces 25 in addition to su~stantial improvement in low temperature performance.
Certain of the pressure-~ensiti~e adhesive tapes of the invention exhibit significantly improved adhesion to the newer automotive paints. Such paints 30 are designed to reduce pollution, and retain durable high gloss finishes. Conventional Adhesives have g~eatly reduced adhesion to such paints as compared to older paint formulations. Some examples of these newer types of automotive paint include BASF/Inmont paints 35 "E-l4'l and "E-l76", DuPont paints "M33J-lO0" and "RK-3840", and "50-J", and Asahi Chemical Co. Ltd.
paint "Lumiflon".

WO92/20751 PCT/US92/~120 Certain preferred pressure-sensitive adhesive tapes of the invention also exhibit improved low temperature detachment when subjected to an automotive industry test referred to as the "cold slam" test at 5 temperatures of between -30C and -45C.
Without wishing to be bound by theory, it is believed that these certain pressure-sensitive adhesive tapes exhibit improvements in paint adhesion and resistance to detaching at low temperatures because of lO the unique morphology of the continuous silicone phase and the excellent chemical interaction of the acrylic copolymers with painted substrates.
In a specific embodiment for a tape construc:tion adherable to automotive paints, one release liner of a 15 transfer tape is typically removed and the exposed adhesive layer is firmly contacted and adhered to a foam layer material such as those discussed above.
Useful foam layer materials typically have thicknesse~
of about 0.3 mm to about 4 mm. The thickness of the 20 foam layer can vary, depending upon the intended application. Foam layers are especially uæeful to prevent low termperature detachment. The opposite side of the foam layer is typically coated with a conventional pressure-sensitive adhesive that adheres 25 well to an auto body side molding, etc. Such adhesives are disclosed in Re 24,90l. The remaining release liner which carries the adhesive of the invention can be removed for application of the adhesive coated foam layer, having a body side molding, etc. firmly adhered 30 to its opposite side, to a painted car door, etc.
In one embodiment of tape constructions adherable to paint, the foam layer comprises an ultraviolet-radiation polymerized acrylic copolymer which may incorporate similar or dissimilar acrylic 35 monomers in like or unlike thicknesses, having similar or different additives from those acrylic copolymers contained in the adhesive layer comprising the adhesive of the invention. The foam layer comprises about 80 WO9V20751 PCT/US92/~120 2 1 033 ~ 9 parts to about 99 parts of an alkyl acrylate monomer, and correspondingly, about 20 parts to about 1 part of a copolymerizable modifier monamer, based upon 100 parts by weight of acrylic monomer, i~e~, alkyl 5 acrylate monomer plus modifier monomer. The foam layer may further include a gas and/or microspheres. The microspheres may be glass or polymeric. The microspheres preferably have an average diameter of about 10 to about 200 micrometers and comprise about 5 10 to about 65 volume percent of the foam layer. The gas can be an inert gas, such as nitrogen, that is mixed into the monomers to form a froth prior to polymerization. Other useful materials that can be blended into the foam layer composition include, but 15 are not limited to fillers, such as silicas, hydrophobic silicas, pigments, foaming agents, antioxidants, and viscosity adjusting agents.
The adhesives of the invention also show utili~y as an adhesive for wound dressings and tapes used on 20 mammalian skin. Adhesives for wound dressings must be non-irritating to the skin. It is also desirable to have a fairly low adhesion initially so that the dressing can be re-positioned, but should not have excessive adhesion build over time. An adhesive that 25 has too high of an adhesion to skin can be difficult and painful to remove.
The adhesive can be coated onto any backing suitable for dressings. In general, the backings should be flexible to conform well to the skin, and 30 breathable, i.e., be permeable enough to have adequate moisture vapor transmission to prevent moisture build-up under the dressing but impermeable to bacteria and other contaminants. Backings are typically made of nonwoven materials, cloth, polymeric films, and the 35 like. The backing can be made from a variety of materials including rayon, polyesters, polyolefins such as polyethylene, cotton, and polyurethanes. Suitable backings include those disclosed in Copeland, U.S.
:

o33 ~g - 28 -Patent No. 3,121,021, and Heineke, U.S. Patent No.4,917,929, both assigned to the assignee of the present application. For certain applications, such as for a dressing over an intravenous needle, it is desirable 5 that the backing material be substantially transparent so that the position of the needle can be monitored.
Polyurethane films are particularly well suited for this application, due to their transparency as well as their breathability.
In the case of preparing a construction adherable to skin, one release liner is typically ~
removed and the adhesive layer is firmly contacted and adhered to a suitable backing. The adhesive composition can also be coated onto the backing and 1 cured if the backing is transmissive to ultraviolet light.
In addition to general multipurpose applications and specific paint and medical applications, the adhesives of the invention have other additional 20 advantages. In some cases, when an adhesive is coated onto a substrate and covered with a silicone release liner, it is desirable for the adhesive to remain releasably adhered to the liner until it is ùsed.
However, conventional acrylate adhesives release easily 25 from silicone coated liners and may pop off prematurely to expose the adhesive to contamination and dust. The adhesives of the invention can e~hibit improved adhesion to the liner so that the liner remains adhered until the adhesive is used. The adhesive composition 30 of the invention can be varied, i.e., by adjusting the amount of silicone PSA in the adhesive composition to control the adhesion of the resultant adhesive to the release liner. This is important in situations where an adhesive coated sheet is die-cut and it is desired 35 that the liner remain adhered to the adhesive or when adhesive coated substrates are exposed to low temperatures as can occur in storage or in shipment and liner pop-off can occur.

WO92/20751PCT/US92/~120 2~L033~9 Testinq Procedures The following tests have been used to evaluate adhesives of the invention. All percentages, parts and ratios within the specification, including the 5 examples, and the claims are by weight unless specifically stated otherwise.

Analysis of Adhesive_Morpholoay by Transmission Electron Microscopy (TEM2 10Thin sections (500-10G0 Angstroms) for TEM
testing were prepared at a sampla temperature of -140C
using a Reichert-Jung~ Ultracut EY cryoultramicrotome equipped with an FC4 cryoattachment. A Diatome~
diamond knife with a stainless steel boat was employed.
15 The sections were examined using a JEOL 100 CX elec:tron microscope in transmission mode operated at 100 kV.

90 Peel Adhesion from Painted Substrate A strip of anodized aluminum 19 mm x 200 mm x 20 0.125 ~m is positioned on one adhesive face of the tape sample. Pressure is applied to the aluminum by rolling with a 2 kg roller. The opposite face of the sample is then firmly bonded to a rigid painted substrate. After the specified dwell time at room temperature, the 25 sample is removed by pulling the aluminum strip at 90 to the adhesive surface at a speed of 30.5 cm/minute, noting the average adhesion in N/cm width, and the failure mode. Foam split (FS) is the most desirable failure mode as it indicates adhesion to the substrate 30 is stronger than the internal strength of the foam layer.
, Static Shear Test A sample is prepared by cutting a 2.54 cm by 35 1.27 cm piece of foam that is coated on one side with the pressure-sensitive adhesive of the present invention and coated on the other side with a conventional acrylic pressure-sensitive adhesive, such W092~2075l PCT/U~g2~W120 a?~ose disclosed in Re. 24,906 (Ulrich). A composite is then formed by sandwiching the sample between a 5 cm by 5 cm steel panel that has been painted with 50-J
paint and a 1.4 cm by 5.O cm by 0.8 mm smooth steel 5 strip having a hole at one end such that the pressure-sensitive adhesive of the present invention is in contact with the paint and the conventional pressure-sensitive adhesive is in contact with the steel strip at the end opposite that having the hole.
10 The contact area to be tested is 2.54 cm by 1.27 cm.
The portion of the panel and the strip that are not in contact with the adhesive extend away from the sandwiched sample in opposite directions from each other. The composite is then rolled down with two 15 passes of a 2 kg roller and aged for 1 hour at room temperature. The panel is then hung at 2 degrees from the vertical for 15 minutes in an air circulating oven which has been preheated to 70C. A 500 gram weight is then hung from the hole in the steel strip and a timer 20 ic started. The time at which the weight falls is the "Static Shear Value" in minutes. If no failure occurs after 10,000 minutes, the test is discontinued.

Cold Slam A rigid vertical steel frame approximately 40 cm .

square is provided at its upper edge with a similar dimensioned hinged frame/door. 19.4 square cm (2.54 cm x 7.62 cm) of medium density silicone foam is mounted at the lower outer edge of the fixed vertical frame (where the hinged door impacts when slammed).
Test panels are prepared as follows:
A 12.7 mm x 125 mm pressure-sensitive attachment tape, carried on a release liner, is applied to the 15 mm x 150 mm face of a rigid polyvinyl chloride test bar 35 which is 6 mm thick. The tape is pressed into place by rolling once with a 6.8 kg roller. The liner is then removed from the tape, and the exposed surface having the pressure-sensitive adhesive of the invention is .

WO92/20751 PCT~US92/~120 21 ()33 ~

attached to a freshly painted steel panel (with 50-J
paint) which is 100 mm x 300 mm. Four test bars are attached, in two rows, in the lengthwise direction of the steel panel, with one end of each test bar 5 extending beyond the end of the panel approximately 2.5 cm. After rolling the test panel with a 6.8 kg roller at a rate of 300 mm/min, the panel is allowed to dwell for 3 days at ambient temperature. The specimen is then conditioned at -40C for approximately 12 hours 10 in the cold chamber, which houses the cold slam fixture as described above. The test panel is then secureàl in the fixture, with the test bars and the long dimension of the panel mounted in a horizontal direction.
The following test procedure was designed so 15 that some quantitative estimate of cold slam performance could be obtained, rather than simply a pass-fail rating.
The cold slam test is conducted by raising the.
hinged "door" to a predetermined angle, and releasing 20 it, allowing it to strike the frame and expose the test panel to a slam at cold temperatures. Ten slams are conducted at each of the five possi~le slam angles.
The slam angle and the number of the slam (1-10~ during which any of the four vinyl bars becomes delaminated or 25 detached is recorded. A slam angle of 23 degrees is used initially. If there have been no failures after ten slams at this angle, the angle is increased to 45 degrees. This procedure is repeated until all test bars become detached, or until ten slams at the 180 30 degree slam angle have been conducted. If failure of one or more bars does occur at a specific stage during the initial ten slams, an additional 10 slams are conducted at that stage before advancing to the next slam angle. The results are recorded by documenting 35 the door slam angle/stage and slam number in which delamination begins, or failure occurs. Numerical designation in the form of stages 1-5 correspond to door slam angles of 23, 45, 68, 90, and 180 degrees, WO92/20751 ~ P~T/US92~04120 33~

respectively. Lower stage numbers indicate poor cold slam properties, e.g., 1 or 2. Higher stage numbers indicate excellent cold slam properties, e.g., 4 or 5.
The stage, number of slams, at each stage number of 5 failures, and the failure mode are recorded.

Skin Adhesion Procedure The test procedure used is PSTC-1 which is Test Method No. 1 of the Pressure-Sensitive Adhesive Tape 10 Council, Glenview, IL, Seventh edition (1976), except that the te~t was modified so that the tape could be applied to the human skin surface on a selected area on the individual's back. Tape samples 2.54 cm wide by 5.08 cm long are placed on the back of an individual 15 and rolled down with one forward and one reverse pass of a 1 kg roller (described in Appendix B, Sections .....
2.7.1, 2.8.1, and 2.8.2 of the above referenced specification) moved at a rate of 30 cm per minute.
Adhesion to the skin is measured at a 180 degree angle 20 according to PSTC-1 using a strain gauge mounted on a motor driven carriage. The force of r~moval is reported in grams of adhesion per 2.54 cm width of sample. The rate of removal is 15 cm per minute.
Initial skin adhesion is mea~ured immediately after 25 applying the tape. Aged adhesion is measured after 24 hours of continuous skin contact. Acceptable skin adhesives will generally exhibit an initial adhesion ~alue of between 20 grams to about 100 grams, and a 24 hour sXin adhesion of about 75 grams to about 300 30 grams.
The following examples are to be considered as ! ' illustrative in nature, and are not limiting in any way. The scope of the invention is that which is defined in the claims only.

WO92/20751 PCT/US9~/~120 21033~9 The following terminology, abbreviations, and trade names are used in the examples:

IOA isooctyl acrylate 5 AA acrylic acid IBnA isobornyl acrylate KB-1 2,2 dimethoxy-2-phenyl acetophenone photoinitiator available from Sartomer RT room temperature lQ POP pop off panel, failure mode, no adhesive residue remaining on paint coated substrate FS foam split failure mode, adhesive continued to adhere to paint but foam core layer split (indicates good adhesion - i.e., adhesion is higher than core strength) Sil commercial silicone PSA
Ex Example 20 Acryl the acrylic polymer polymerized from the acrylic monomer (i.e., alkyl acrylate monomer plus modifier monomer) PHR or phr parts per hundred parts acrylicmonomer (i.e., alkyl acrylate monomer plus modifier monomer) WT % weight percent SI/ACRYLIC PSA silicone/acrylic PSA
E-14 a high solids clear topcoat enamel available from Inmont 30 50-J a medium solids enamel available from DuPont designated as 50-J by Ford LDPE low density polyethylene ABS acrylonitrile butadiene styrene Epoxy cured epoxy resin panel 35 TPO thermoplastic polyolefin wt wei~ht min minute.s hr or Hrs hours Init initial W O 92/20751 PC~r/US92/04120 33~

Throughou~ the Examples, the rest of the Specification and the claims all parts, percentages, and ratios are by weight unless otherwise indicated.

Example 1 200 grams of a 55% solids silicone pressure-sensitive adhesive (PSA) in xylene (Q2-7406 available from Dow Corning) were heated at 150C for about 6 hours to obtain a dried silicone 10 pressure-sensitive adhesive that is substantially solvent-free. A mixture having 80 parts isooctyl acrylate (IOA), 20 parts of acrylic acid (AA) and 100 parts of the dried silicone adhesive was mixed until the silicone PSA was dissolved in the IOA/AA monomexs.
15 To this solution was added 0.2 part per hundred acrylic monomer (phr) 2,2-dimethoxy-2-phenyl acetophenone photoinitiator (KB-1 photoinitiator from Sartomer), and 0.15 phr of 2,4-bistrichlo~omethyl-6-(4 methoxyphenyl)-s-triazine as disclosed in U.S. Patent No. 4,330,590 (Vesley). The solution was then mixed with an air driven high shear propeller mixer for about 5 minutes.
The mixture was then degassed, ana knife coated to a uniform thickness of O.05 mm onto a 0~05 mm thick biaxially-oriented polyethyle.ne terephthalate (PET) 25 film, which had been coated with a release agent. A
second PET film as described above was placed over the coated mixture with the release coated side facing the coatingO The coating was polymerized to form a pressure-sensitive adhesive by exposure to a bank of 30 ultravivlet fluorescent lamps, 90~ of the emissions were between 300 and 400 nm with a maximum at 351 nm and which provide radiation intensity of approximately 1-2 mW/cm'. Total exposure was about 400mJ/cm~
(Dynachem units). The resulting pressure-sensitive 3S adhesive had an alkyl acrylate/polar comonomer ratio (IOA/AA) of 80/20 and an acrylate/silicone ratio W092/20751 PCT/US92/0412~
210~9 (acryl/sil3 of 50t50 wherein the acrylate moiety includes both the alkyl acrylate and the polar comonomer.
The top liner was then removedO An acrylic 5 foam-like layer was formed on top of the pressure-sensitive adhesive as will be described. A
solution of 95 parts IOA~ 5 parts AA, and 0.04 part KB-1 was placed in a one-liter mixing vessel equipped with a lid. The vessel was sparged with nitrogen for 10 30 minutes. The solution was then partially polymerized by exposure to W lamps as described above to a viscosity of about 3000 cps. To the mixture was added an additional 0.10 part KB-l, 0.10 part 1,6-hexanediol diacrylate, 8 phr glass microbubbles (C15/250 having average diameters of 80 micrometers available from Minnesota Mining & Manufacturing Co.), and 10 phr silica("Aerosil" 972 from DeGussa). The mixture was knife coated onto the pressure-sensitive , adhesive at a thickness of about 1.0 mm~ A release 20 coated, 0.05 mm thic~ polyester film was placed over the mixture and the top mixture was polymerized with W
light with a total energy of 700 mJ~cm2.
The resulting tape had a foam-like characteristic and was tested for cold slam, peel 25 adhesion, and adhesion build as show~ in Table 1.

Ex~mple 2 A pressure-sensitive adhesive tape was made by knife coating the adhesive solution of Example 1 to a 30 thickness of 0.05 mm as described in Example 1. The partially polymerized mixture for the foam-like layer of Example l was knife coated onto the wet pressure-sensitive adhesive at a thickness of 1 mm. A
second release liner was placed over the mixture and 35 the composite was cured with W light at a total energy of 700 mJ/cm2. The resulting tape was tested for peel adhesion and cold slam as shown in Table 1.

WO92/~0751 PCT/US92/~120 ~3 ~i~ 36 -Example 3 A pressure-sensitive adhesive tape was made by simultaneously coating the adhesive solution of Example l and the partially polymerized mixture of 5 Example l using a coating die having two orifices onto a release coated polyester liner. The thickness of the adhesive layer was 0.05 mm and the foam-like layer was 1.0 mm thick. A second liner was placed over the mixture and the composite was cured with W light at a l0 total energy of 700 mJ/cm2. The resulting tape was tested as in Example l and results are shown in Table l.

Example 4 The mixture for the foamlike layer of Example l was coated to a l.0 mm thickness and cured between two release coated polyester liners with W light at a total energy of 700 mJ/cm2. The foamlike layer was primed and laminated to the polymerized 20 pressure-sensitive adhesive of Example l to make a pressure-sensitive adhesive tape. The tape was tested as in Example l and results are shown in Table l.

Comparative Example C-l To a one liter mixing ve~sel equipped with a lid was added 80 parts of IOA, 20 parts of A~, and 0.04 phr photoinitiator ~KB-l). The resulting solution was sparged with nitrogen and partially polymerized under W light to a viscosity of about 2000 cps~ To the 30 partially polymerized mixture was added an additional 0.16 phr KB-l and 0.15 phr of the triazine described in EXample l. The partially polymerized mixture was knife coated to a thickness of 0.05 mm and cured to make an adhesive transfer tape as described in Example l. The 35 resulting tape was laminated to a foam-like layer, tested as in Example l and results are shown in Table 1.

W 0 92/20751 PCr~US92/04120 21033~9 _ __= _ _ .
Peel Adhesion E-14 Paint-N/cm Cold Slam (-40C)*
20 min.72 hr. 3 Day R~ Dwell Example . Stage,S/F/Fail Mode 1 57.5 82.3 451108-ll//FFs _ 2 30.2 37.4 5;4-1/FS

no failure in last ~ i~ple ..
3 55.6 64.8 5;2-1/FS

_ .. .
4 6 0 O 1~ 2 . 00 ' ' 5, 2--l/FS ~

C-l 1.0 3.6 2-1/POP

. . _ _ _.
* Cold slam is shown by the stage, the number of slams, and the number of failures. The ~lams are ~one con~ecutively, and the failure mode is indicated. FS i9 foam ~plit and POP is the adhesive pops off of the paint panel. For example, "4,10-1/FS"
r~presents one sample failing by foam ~plit on the 10th slam of the 4th stage. "17 l/FS" which $all~ under the 4th ~tage in ~ategory in Table 1 represerlts one ~ampl~ failing by foam split on the 17th slam of the 4th ~tage.
** Fail~re was due to delamination of the ~oam layer and the PS~
of the invention.

The data in Table 1 shows that the PSA of the present invention has superior peel adhesion to paint and superior cold slam properties when compared to a similarly made acrylate PSA without the silicone PSA.
30 The examples show various methods of applying the PSA
to a foam layer. The PSA of these examples is crosslinked. The following examples illustrate the WO92/207~1 PCT/US92/04120 ~,~ o~3~9 ~

peel adhesions provided by the PSAs of the present invention compared to conventional acrylic and silicone PSAs.

Examples 5-19 Pressure-sensitive adhesives were made as in Example 1 except without the triazine, and the amounts of IOA, AA, and silicone adhesive were varied as shown in Table 2.
10A foam-like layer was made by partially polymerizing a mixture of 87.5 parts IOA, 12.5 parts AA, and .04 part 2,2-dimethoxy-2-phenyl acetophenone (Irgacure~ 651 available from Ciba-Geigy Corporation) in a nitrogen atmosphere to a viscosity of about 15 1500 cps under W lights. To the partially polymerized mixture was added an additional 0.1 part Irgacure~ 651, 0.05 part 1,6-hexandiol diacrylate, 4 par`ts hydrophobic silica, and 8 parts glass microbubbles having an average diameter of 50 microns and a density of 20 0.15 g/cm3 (C15/250 available from Minnesota Mining and Manufacturing Co.). The mixture was then coated onto a release agent coated PET liner, covered with a second similar PET liner, and cured as described in Example 1.
The resulting layer had a thickness of about 1.0 mm.
25 The foam-like layer was then primed and the pressure-sensitive adhesive transfer tape was then laminated to the foam-like layer. The resulting tape construction was test~d for peel adhesion and adhesion build with test results as shown in Table 2.
Comparative Example C-2 A pressure-sensitive adhesive transfer tape was made as in Example C-1 and laminated to a foam-like layer as in Example 5. Test results are shown in 35 Table 2.

WO92/207SI PCT/VS9~/~120 _ 39 _ 21033~
ComParative Example C-3 Dow Corning Q2-7406 was mixed with 2%, by weight of the silicone solids, dichlorobenzoyl peroxide catalyst. The adhesive was coated onto a Q2-7785 5 release liner (available from Dow Corning) to provide a dry coating thickness of O.OS mm. The coated adhesive was cured in an oven for 1 minute at 70C and for 2 minutes at 168C, and the resulting pressure-sensitive adhesive was lamina~ed to the primed foam-like layer of 10 Example 5. Test results for peel adhesion are shown in Table 2.

, ~ ~
15composition - Peel Adhesion Peel Adhe~;
parts by weight 50-J Paint-N/cm E-14 Paint-N/cm . , . , 11 Example IOA/AA Acryl/Sil* 20 min 72 hr 20 min 72 hr ¦
Ratio Ratio 80/20 5~/`50 _ 30.0 62.2 18.5 48.5 20 6 95/5 70/30 ___ ___ 9 5 13.6 _ . r .
795/5 60/40 ___ ___ 10.5 15.8 8 92/8 60/4016.5 26.3 11.1 15.7 9 90/10 50/50_ _20.5 32.7 15.1_ 16.6 90/10 60/40___ ___ 13.1 23.0 l _ _ . I
2511 86.14 70/30_18.1 _62.9 14.3 23 12 85/15 70/30___ ___ 11.7 40 2 l . _ . _ . _ _ I
3 85/15 60/40 __ _ _ 27.3 38.5 14 85/15 S0/50 ___ ___ 24.3 31.1 83/17 60/40 21.7 62.6 22.4 30.1 I _ . _ 16 80/20 70/30 ___ ___ 8.6 13.7 I . . _ 17 _80/20 ~0/40 ___ _ __ 19.3 2~.3 18 80/2040/60 _ 21.6 37.5 ___ ___ 19 70/30`50l50_ 15.8 1e.s 10.9 8.9 C-2 80/20 4.8 10.1 ___ ___ 35C-3 DC7406 12.5 16.9 14.5 18.5 -*Ratios are defined in Example 1.

WO92/20751 PCT/US92/~120 ~33~ 40 -Table 2 shows the excellent adhesion build of PSAs of the invention on automotive paints as compared to conventional acrylic or silicone PSAs. As the ranges of IOA, AA, and silicone PSA approach the outer 5 limits of the preferred formulations, the adhesion properties approach the performance of straight silicone PSAs. The performance varies with the specific type of paint.
The following examples illustrate the superior 10 cold slam performance of the PS~ of the present invention as compared to a conventional acrylic PSA.

Examples 20-26 A foamlike layer was made as disclosed in U.S.
15 Patent No. 4,415,615 using a mixture of 87.5 parts IOA, 12.5 parts AA, 0.04 part Irgacur~ 651, 2 parts of silica ("Aerosil" 972 from DeGussa Cor~.) 8 parts of glass microbubbles having an average diameter of 50 microns and a density of 0.15 g/cm3, and 4 parts of the 20 surfactant described below. The mixture was frothed to a void volume of 0.6 g/cm3. The foam layer was primed.
Pressure-sensitive adhesive transfer tapes were made as in Example 1, without the triazine, with varying amounts of IOA, AA, and silicone PSA as indicated in 25 Ta~ble 3. The transfer tapes were laminated to the foam layer. Cold slam test results are also shown in Table 3.
To a glass reactor fitted for stirring, vacuum, nitrogen inlet, heating, cooling, and distillation are 30 added 117 parts of heptane, 20 parts of N-ethyl perfluorooctanesulfonamidoethyl methacrylate, and 20 parts of C~8H3~O2CC(CH3)=CH2. The contents of the reactor are heated to 55C, and the reactor was purged with nitrogen. To the reactor was added 0.3 part benzoyl 35 peroxide (dissolved in 3 parts heptane). The content of the reactor were heated to 65~C, and maintained at that temperature for 4 hours with constant stirring.
The heptana was stripped from the resulting .

WO92/20751 PCT/US92/~120 2 1 0 3 3 ~ ~

fluoroaliphatic oligomer under vacuum. The solid oligomer was then dispersed in toluene to form a 50%
solids solution of a surfactant.

Comparative Example_C-4 An adhesive transfer tape was made by coating the foam-like layer of Example 20 with a solvent based adhesive. The adhesive was made by mixing 87.4 parts IOA, 53.2 parts methyl acrylate, and 11.4 parts AA in 10 248 part~ ethyl acetate with 0.46 part Vazo~ 64 initiator (available from DuPont) in a nitrogen atmosphere and heating at 55C for 24 hours with constant mixing. The solution was diluted to 21%
solids, 0.5 part of a crosslinker was added, and the 15 solution was coated onto the primed foam-like layer of Example 20 and dried. Test results are shown in Table 3.

WO9~/20751 PCT/US92/~120 ~33~ - 42 -Composition -Parts by Weight Cold Slam (-40C) IOA/AAAcryl/Sil 3 Day RT Dwell Example RatioRatio Stage,S-F/Fail Mode 95/570/30 5,1-2/FS

21 95/550/50 4,3-1/FS

_ _.
22 86/1470/30 12~1/FS
_ _ 23 85/1570/30 4,10-1/FS

_ .
2~ 85/1560/40 5,1-2/FS

Z5 _ 50~5~ 13-1/FS

26 80/2050/50 5,~_1/FSS
. _ lS L _ _ The test results in Table 3 show superior cold slam test performance of the PSAs of the invention as 20 compared to a solvent based acrylic adhesive.
.

WO92J20751 2 1 o 3 3 ~ 9 PCT/USg2/04120 Examples 27-31 The pressure-sensitive adhesives of these examples were made as in Example 1, without the triazine with varying amounts of IOA, AA, and silicone 5 PSA. The pressure-sensitive adhesives were laminated to a foam-like layer as described in Example 20 and tested for peel adhesion and cold slam. Test results are shown in Table 4.
Table 4 shows the superior balance of adhesion, 10 adhesion build, and cold slam properties of adhesives of the invention intended for autGmotive paint applications. The cold slam is still superior even though peel adhesion may be low in cases where the PSA
coated substrate is removable.

WO 92/20751 PCI`/USg2/Q4120 I
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WO92/207SI PCT/US92/~120 21033~

Examples 32-33 Foamlike tapes were made using the pressure-sensitive adhesive of Example 1 on the foam-like layer described in Example 20. Test results 5 for cold slam are shown in Table 5.
The examples show the excellent cold slam performance of crosslinked adhesives of the invention compared to a solvent~based adhesive (C-4) and an acrylate adhesive without silicone (C-2).

_ _ . _. --Compos it ion -Parts by Weight . __ Cold Slam ~-40C) IOA/AA Acryl/Sil 3 Day RT Dwell Example Ratio Ratio Stage, S-F/Fail Mode 32 85 /15 70/ 30 2 - l /FS
~ _ 3 3 5 0 / 5~ C--l / FS

~; `~ _ 2'3-1/POP
.C--4 __ ~ 3, 1 _ 2 / POP

Pressure-sensitive adhesive tapes were made as in Example 33 except that different crosslinking agents were employed. Each tape was laminated to the foam-like layer of Example 5. The tapes were tested for static shear and adhesion.

3 3 ~

The adhesive of Example 34 was made as in Example l except that the triazine was omitted and 0.25 part, per hundred parts of acrylic monomer plus silicone, of gamma-glycidoxypropyltrimethoxy silane (available from Petrarch Systems, Inc~) was added to the mixture before coating.
The adhesive of Example 35 was crosslinked with triazine as described in Example l. Example 5 was not crosslinked.
Results in Table 6 show that the adhesive of the invention can be crosslinked to improve the static~.
shear properties without deleteriously affecting adhesion.

.. . __ Compos it ion -Peel Adhesior~
Parts by Weight50-J Pa: nt-N/cm Static Shear~
IOA/AA Acryl/Sil minutss to Example Ratio~atio 20 min72 hr failure 34 80120~0/50 32 . 646. 9 >10, 000 . . _. _ _ 35 _ 80/2050150 27 . 547 . 3~10, 000 5 _ 80/2050/50 30 . 062 . 2 _ 275 Examples 36-4l The adhesives of Example 5, C-4 and GE 600 were 30 laminated to the foam layer of Example 20, and tested on various substrates as shown in Table 7. The generic substrate test panels were obtained from the Precision Punch & Plastics Company of Minnetonka, Minnesota. The TPO is a thermoplastic polyolefin that is identified as 35 Tadlar~ thermoplastic polyolefin 88N809.

W O 92~20751 PCT/US92~04120 - 47 - 210~

Peel Adhesion - N/cm Ex. 5 xx. C-4 GE 600~
Ex.Substrate 20 90 20 90 20 90 _ min. hr. min. hr. min. hr.
36Polypropylene14.0 23.0 6.1 8.3 11.8 _ 17.3 37Polycarbonate36.8 41.0 57.9 51.9 9.9 24.3 10 38 LDPE 13.3 18.6 3.3 5.7 12.3 17.5 39 ABS 25.0 33.3 ~9.3 41.8 14.9 _ 1.7 40 Epoxy 21.0 33.1 21.5 33.1 ll.o 1.0 , 41 TP0 17.3 1~.9 5.7 3.3 _ = ___ * GE 600 is a ~olvent based polydimethyl ~ilicone pre~ure ~ensitive adhesive composition from General Electric Company.
The composition is mixed with 2% Iby weight of silicone solids) of dichlorobenzoyl peroxide, coated onto a rele~e liner to provide a dry adhesive thickness of 0.05 mm. The coated adhesive was dried at 70C for l minute and cured at 165C for 2 minutes.

The results in Table 7 show acceptable to 25 superior adhesion of the adhesive of the invention to a variety of polymeric substrates.

ExamPle 42-47 Pressure-sen~itive adhesives were made as in 30 Example 1 except that the ratios of the components were varied as shown in Table 8. Tapes were made by removing one of the liners and laminating the adhesive surface to an embossed nonwoven backing useful as a medical bandage. The other liner was removed and the 35 resulting tape constructions were tested according to the test described above for the skin adhesion procedure. The results shown in Table 8 indicate that the adhesives of the invention are suitable for medical uses such as ~andages as compared to a product having 40 good commercial acceptability.

W O 92/207~1 PCT/us92/041~0 2~033~9 . - _ _ Compouition - Adhe~ion to Skin Parts b~ r Weightgrams/ 25.4 mm Example IOA/AA Acryl/Sil Ratio Ratio_Init. _ 24 Hrs. ¦
42 90/l0 60/40 69 135 43 80!20 _ 40~60 36 l06 44 90/l0 50/50 _85 149 8~/15 40/6Q 53 159 . , . _ __ .
46 95/5 7Q/30 90 137 l . _ .
. 4~ 95/5 50/50 1 94 159 1 . . _ I , .

l Tape* _ . ~! _ _ 120 lS
* Pressure-sensitive adhesive tape available from Minnesota Mini~g and Manufacturing Co.

Examples 48~54 Pressure-sen~itive adhesive transfer tapes were made as described in Example 1 except that the IOA/AA
ratios were varied and the acrylate/silicone ratios were varied. One of the liners was removed and the 25 adhesive was laminated to a 0.2 mm thick polyurethane ~ilm to provide a wound dressing. The coated wound dressing was sterilized with 3 megarads of gamma radiation. The tapes were tested for adhesion to skin.
The results shown in Table 9 indicate that the 30 adhesives of the invention are suitable for medical uses such as wound dressing compared to a product having good commercial acceptability.

WO92/20751 PCT/US92/~120 21 033 ~ 9 _ _ ~ ~ ~
l Composition - Adhesion to S~in l Partq b r Weight grams, 25.4 mm _ ¦ Example IOA/AA Acryl/Sil Rat io Ratio Init. 24 Hrs.
~8 95/5 70/30 66 169 .

. __ .

. , 51 95/5 40/60 ~1 171 . .~

, . _ . _~ _.,, . , . .. _ _ _ s4 90/l0 40/60 51 217 .. , . . . - ~.. . . ._ Tegaderm~ 40 140 _ ,. ~ .

* Tegaderm~ is a wound dre~Ring a~ailable from Minnesota Mining and Manufacturing Co.

Examples 55-58 Pressure sen~itive adhesive transfer tapes were made as in Example l except that the ar.rylic acid was omitted, 0.l part of KB-l ~per hundred parts total of IOA and silicone PSA) and 0.075 part of the`triazine of 25 Example l tper hundred parts total of IOA and silicone PSA) were added. Various ratios of IOA/sil were made as shown in Table l0. Wound dressings were made as described in Example 48 and were tested for adhesion to skin. The test results in Table 10 show that the PSA
30 of the invention is useful when the alkyl acrylate is used with no comonomer, and the resulting wound dressings are suitable for ~edical uses as compared to a product having good commercial acceptability.

3` - sn - ~
TABLE l0 , . _ .
Compo~ition - Adhesion to Skin Parts by Weight grams/25.4 mm Example IOA sil Init. 24 Hrs.
_ 5~ 40 60 59 169 . .
Tegaderm~ 44 _137 Examples_59-62 Pressure sensitive adhesive transfer tapes were made as in Example l except that varying amounts of IOA
and isobornyl acrylate (IBnA) were used instead of IOA/AA. The acryl/sil ratio was kept at 60/40, 0.l phr KB-l (per hundred parts total acrylic monomer and 20 silicone PSA) was added and 0.075 part triazine of Example l was added. The tapes were made into wound dres~ings as in ~xample 48, and tested for skin adhesion. The adhesive compositions and test results in Table ll show that th~ adhesive of the invention 25 having a nonpolar commomer is useful for making wound dressings as compared to a commerci~lly acceptable product.

TABLE ll . ~-- -- ~ -- _ .
Composition - Adhe~ion to Skin Parts b~ r Weight grams~ 25.4 mm ! ~ Example IOA/IBnA Acryl/Sil _ Ratio Ratio Init.24 Hrs.
S9 95/5 60/40 69 ____ 193 /
61 ~5/15 60/40 69 184 .
Te~aderm~ _ 44 137 WO92/20751 - S1 ~ 2 1 o 3 3 ~ ~ PCT/US92/04120 While this invention has been described in connection with specific embodiments, it should be understood that it is capable of further modification.
5 The claims herein are intended to cover those variations which one skilled in the art would recognize as the chemical equivalent of what has been described here.

Claims (10)

Claims

1. A radiation curable pressure-sensitive adhesive composition comprising:
(a) from about 5 parts to about 95 parts by weight of acrylic monomer wherein said acrylic monomer comprises:
(i) from about 50 to about loo parts by weight of alkyl acrylate monomer, the alkyl groups of which have an average of 4 to 12 carbon atoms; and (ii) correspondingly from about 50 parts to about O parts by weight of a monoethylenically unsaturated copolymerizable modifier monomer;
wherein said amounts of (i) and (ii) are selected such that the total amount of (i) plus (ii) equals 100 parts by weight of said acrylic monomer;
(b) correspondingly from about 95 parts to about 5 parts by weight of silicone pressure-sensitive adhesive;
wherein the amounts of (a) and (b) are selected such that the total amount of (a) plus (b) equals 100 parts by weight, (c) about O part to about 5 parts by weight of a photoinitiator based upon 100 parts by weight of said acrylic monomer; and (d) about 0 to about 5 parts by weight of a crosslinker based upon 100 parts by weight of (a) plus (b).

2. A pressure-sensitive adhesive comprising a radiation cured pressure-sensitive adhesive composition, wherein said pressure-sensitive adhesive composition comprises:
(a) from about 5 parts to about 95 parts by weight of acrylic monomer wherein said acrylic monomer comprises:

(i) from about 50 to about 100 parts by weight of alkyl acrylate monomer, the alkyl groups of which have an average of 4 to 12 carbon atoms; and (ii) correspondingly from about 50 parts to about 0 parts by weight of monoethylenically unsaturated copolymerizable modifier monomer;
wherein said amounts of (i) and (ii) are selected such that the total amount of (i) plus (ii) equals 100 parts by weight of said acrylic monomer;
(b) correspondingly from about 95 parts to about 5 part by weight of a silicone pressure-sensitive adhesive wherein the amounts of (a) and (b) are selected such that the total amount of (a) plus (b) equals 100 parts by weight;
(c) about 0 part to about 5 parts by weight of a photoinitiator based upon 100 parts by weight of said acrylic monomer; and (d) about 0.01 to about 5 parts by weight of a crosslinker based upon 100 parts by weight of (a) plus (b).

3. The pressure-sensitive adhesive of claim 2 wherein said pressure sensitive adhesive composition comprises about 30 to about 70 parts by weight acrylic monomer and about 70 to about 30 parts by weight silicone pressure-sensitive adhesive.

4. A pressure-sensitive adhesive tape comprising a substrate coated on at least a portion of one side with the pressure-sensitive adhesive of claim 2.

5. A pressure-sensitive adhesive tape of claim 4 wherein said substrate comprises a foam layer.

6. The pressure-sensitive adhesive of claim 2 wherein said silicone pressure-sensitive adhesive comprises the intercondensation product of a polydiorganosiloxane and a silanol functional copolymeric silicone resin.

7. The pressure-sensitive adhesive of claim 6 wherein said polydiorganosiloxane comprises polydimethylsiloxane.

8. The pressure sensitive adhesive tape of claim 4 further including a release coating on at least one side of the substrate.

9. The pressure sensitive adhesive tape of

claim 9 wherein the release coating is selected from the group consisting of silicones, fluorosilicones, and polyfluoropolyethers.

10. A method of preparing a pressure-sensitive adhesive comprising the steps of:
(a) combining (I) from about 5 parts to about 95 parts by weight of acrylic monomer wherein said acrylic monomer comprises:
(i) from about 50 to about 100 parts by weight of alkyl acrylate monomer, the alkyl groups of which have an average of 4 to 12 carbon atoms; and (ii) correspondingly from about 50 parts to about 0 parts by weight of a monoethylellically unsaturated copolymerizable modifier monomer;
wherein said amounts of (i) and (ii) are selected such that the total amount of (i) plus (ii) equals 100 parts by weight of said acrylic monomer;
(II) correspondingly from about 95 parts to about 5 parts by weight of silicone pressure-sensitive adhesive;

wherein the amounts of (I) and (II) are selected such that the total amount of (I) plus (II) equals 100 parts by weight; and (III) about 0 part to about 5 parts by weight of a photoinitiator based upon 100 parts of said acrylic monomer;
in order to form a pressure-sensitive adhesive composition; (b) coating said pressure-sensitive adhesive composition onto a substrate; and (c) exposing said adhesive composition to radiation until said adhesive composition is substantially cured.