GB2151243A - Production of ultraviolet radiation-curable silicone release compositions with acrylic functionality - Google Patents

Description

SPECIFICATION Production of ultraviolet radiation-curable silicone release compositions with acrylic functionality This invention relates to the production of organosiloxane polymers and curable compositions made therefrom. More particularly, it relates to the production of organopolysiloxane compositions having acrylic functionality, and optionally also epoxy functionality, and to ultra-violet radiation-curable release coatings made therefrom which render a normally adherent surface relatively adhesive..

Silicone compositions have long been used as release coatings, which render a surface or material relatively non-adherent to other materials which would normally adhere thereto. For example, silicone release compositions have found application as coatings which release pressure-sensitive adhesives for labels, decorative laminates, transfer tapes, etc. Silicone release coatings on paper, polyethylene, Mylar and other such substrates are also useful to provide non-stick surfaces for food handling and industrial packaging.

Previously developed silicone release compositions have been heat curable, but silicone resins which can be cured with ultraviolet radiation are desirable.

Ultraviolet radiation (UV) is one of the most widely used types of radiation because of its low cost, ease of maintenance, and low potential hazard to industrial users. Typical curing times are much shorter, and heat-sensitive materials can be safely coated and cured under UV radiation where thermal energy might damage the substrate.

Several UV-curable silicone systems are known: U. S. Patents 3,816,282 (Viventi); 4,052,059 (Bokerman et al.) ; and 4,070,526 (Colquhoun) describe compositions wherein w-mercaptoalkyl substituted polysiloxanes react with vinyl-functional silixones in a free-radical process when exposed to UV radiation. These compositions, however, often require scarce or expensive starting materials, have unserviceably slow cure rates, or emit offensive odors (associated with the mercaptan group) which persist in the cured products.

UV-curable silicone resins with epoxy or acrylic functionality have been found recently to have the high degree of reactivity to make them suitable for release applications while avoiding the disadvantages of known UV-curable systems. Epoxy silicone compositions, such as described in U. S. Patent 4,279,717 (Eckberg et al.), are especially advantageous for their rapid curing in the presence of certain onium salt photoinitiators. Certain acrylic-functional polymers can be cured to adhesive coatings under UV radiation in the presence ofvariousfree-radical-type photoinitiators.

The present invention provides an organopolysiloxane having acrylic functionality prepared by hydrosilation addition of a hydrogen-functional polysiloxane fluid and an alkene halide selected from allyl chloride and methallyl chloride, followed by reaction of the product of said hydrosilation with a hydroxy-functional acrylate selected from acrylic acid, methacrylic acid, hydroxyethyl acrylate and hydroxyethyl methacryla'a, in the presence of a tertiary amine.

The present invention also provides an organopolysiloxane having epoxy and acrylic functionality prepared by (1) performing a hydrosilation addition of a hydrogen-functional polysiloxane and an epoxy olefin compound without reacting all of the hydrogen-silicon groups in said polysiloxane ; (2) reacting the product of step (1) with an w-halogen-containing olefin by hydrosilation addition; and (3) reacting the product of step (2) with an hydroxy-functional acrylate compound in the presence of pyridine.

The present invention additionally provides ultra-violet radiation-curable polysiloxane release coating compositions comprising (A) a polysiioxane product as defined above, and (B) a catalytic amount of a photoinitiator comprising (i) an onium salt having the formula: R21+ MXn-, or R3S+ MXn-, or RsSe"MXn, or R4 ?' MXn', or R4NT MXn-, where R can be the same or different organic radical, including aromatic carbocyclic and heterocyclic radicals, of from 1 to 30 carbon atoms, and MXn-is a non-basic non-nucleophilic anion, (ii) a free-radical photoinitiator, or (iii) a combination of (i) or (ii) above. Optionally, (C) an amount of epoxy-functional monomers sufficient to enhance the cure of said composition may also be present.

Our co-pending Application GB-A-2119809, from which the present Application is divided, relates to a poly-organosiloxane containing units of the formula:

where R is H or Co 3+ alkyl and G is, independently, C0 3s alkyl, or an epoxy-functional organic radical of from 2 to 20 carbon atoms, with at least one polymer unit being acrylic-functional.

Another feature of the present invention includes UV-curable silicone release compositions comprising silicone compounds exhibiting acrylic functionality, or both acrylic and epoxy functionality, and a catalytic amount of a photoinitiator or a silicone-soluble free-radical photoinitiator, or a mixture thereof.

Another feature of the present invention includes the addition of reactive diluents, such as epoxy monomers, to the release compositions herein to enhance the cure of the compositions.

The expoxy-functionai, acrylic-functional and epoxy-and-acrylic-functional silicones of the instant invention are best prepared by stepwise addition of functional groups to silane or siloxane fluids via processes and from precursor materials described hereinafter in detail. The resulting silicone resins can then be cured by dissolving a suitable photoinitiator (or combination of photoinitiators) in the resin and exposing them to ultraviolet radiation. The resin harden to a tack-free, smear-free condition, usually in from one second to ten minutes, and in preferred features of this invention less than one second.

U. S. 4,279,717 (Eckberg et al.) describes the addition of a vinyl epoxide monomer to a methyl-hydrogen silicone polymer fluid. While this is a proven means of obtaining epoxy-functional silicones, there are drawbacks associated with the nature and availability of the vinyl epoxy monomer starting materials. Many unsaturated aliphatic epoxies, such as 1-butene-3, 4-epoxide and allyl-glycidyl ether, are suspected carcinogens; and 4-vinyl-cyclohexeneoxide, the preferred starting material of the above-mentioned Eckberg et al. patent, is now unavailable commercially.

The necessity of working with dangerous materials can be eliminated by a feature of the invention herein which is a method of preparing the-(3, 4-epoxy cyclohexyl) ethyl-substituted silicone fluids preferred for paper release applications from non-epoxy starting materials.

It is known in the art that terminal olefins add silicon hydrides more readily than do internal olefins. See, Speier, J. L., Webster, J. A., and Barnes, G. H., Journal theAmerican Chemist Society, 79,974 (1957). From this it was discovered that many dioiefins, such as 4-vinylcyclohexene could undergo addition to =SiHfunctional fluids in the following manner, similarly to the addition of 4-vinylcyclohexeneoxide described in the Eckberg et al. patent: (I)

In this manner ss-(3, 4-cyclohexenyl) ethyl-functional dimethyi silicone fluids are synthesized which can subsequently be epoxidized te yield (3- (3, 4 epoxy cyclohexyl) ethyl-functional silicone fluids which are known and very desirable for release coating uses.

These ethyl cyclohexenyl-substituted silicone fluids are epoxidized by contact with any of several reagents commonly used to convert olefins to epoxides. For the purposes herein, organic peracids having the general formula RCO-O-OH, where R is a monovalent hydrocarbon radical of from 1 to 20 carbon atoms, are suitable to accomplis the desired epoxidation, which may be represented as follows :

Other epoxidation agents, such as organic hydroperoxides, may also be used. Peracetic acid (40%) and tetrabutyl-hydroperoxide are preferred.

The foregoing two step process is a novel means of producing ss-(3, 4 epoxy cyclohexyl) ethyl silicone fluids which can be combined with catalytic onium salts (described infra) and thereafter cured to abhesive coatings by brief exposure to ultraviolet radiation.

In this manner other inexpensive and readily available diolefins, including vinyinorbornene, cyclooctadiene, vinylcyclopentene, allylcyclohexene, and the like can be used to produce organopolysiloxane polymers having unsaturated sites which are easily and safely epoxidized. The resulting epoxy-functional silicones are UV-curable in the presence of onium salts and are useful as paper release compositions.

Another feature of the present invention is the discovery of other epoxy-functionai silicone fluids which, fihough structurally different, are of comparable performance and attractiveness as release compositions to P- (3, 4-epoxy cyclohexyl) ethyl silicones. These compositions are prepared from readily available epoxide starting materials and so avoid a major drawback of previously known epoxy-functional release compositions.

The epoxy-functional polydiorganosiloxane silicone fluids provided by the present invention are more specifically dialkylepoxy-chainstopped polydialkyl-alkylepoxysiloxane copolymers wherein the polysiloxane units contain lower alkyl substituents, notably, methyl groups. The epoxy functionality is obtained when certain of the hydrogen atoms on the polysiloxane chain of a polydimethyl-methylhydrogensiloxane copolymer are reacted in a hydrosilation addition reaction with other organic molecules which contain both ethylenic unsaturation and epoxide functionality. Ethylenically unsaturated species will add to a polyhydroalkylsiloxane to form a copolymer in the presence of catalytic amounts of a precious metal catalyst. Such a reaction is the cross-linking mechanism for other silicone compositions, however, in the pl.-sel 1 ; inventivn, â wol ; ; rolled amount of such cross-linking is permitted to take place in a silicone precursor fluid or intermediate, and this is referred to as"pre-crosslinking". Pre-crosslinking of the precursor silicone fluid means that there has been partial cross-linking or cure of the composition and offers the advantages to the present invention of enabling swift UV-initiated cure with little expense for energy and elimination of the need for a solvent.

The ultraviolet-curable epoxy-functional silicone intermediate fluid comprises a pre-crosslinked epoxy functional dialkylepoxy-chainstopped polydialkyl-alkyl-epoxy siloxane copolymerfluid which is the reaction product of a vinyl-or allylic-functional epoxide and a vinyl functional siloxane cross-linking fluid having a viscosity of approximately 1 to 100,000 centipoise at 25 C with a hydrogen-functional siloxane precursor fluid having a viscosity of approximately 1 to 10,000 centipoise at 25 C in the presence of an effective amount of precious metal catalyst for facilitating an addition cure hydrosilation reaction between the vinyl-functional cross-linking fluid, vinyl-functional epoxide, and hydrogen-functional siloxane precursorfluid.

The vinyl-or allyl-functional epoxides contemplated are any of a number of aliphatic or cycloaliphatic epoxy compounds having olefinic moieties which will readily undergo addition reaction toSiH-functional groups. Commercially obtainable examples of such compounds include 1-methyl-4-isopropenyl cyclohexeneoxide (limoneneoxide ; SCM Corp.) ; 2,6-dimethyl-2,3-epoxy-7-octene (SCM Corp.) and 1,4-dimethyl-4 vinylcyclohexeneoxide (Viking Chemical Co.). Limoneneoxide is preferred.

The precious metal catalystforthe hydrosilation reactions involved in the present invention may be selected from the group of platinum-metal complexes which includes complexes of ruthenium, rhodium palladium, osmium, iridium and platinum.

In the present invention, the vinyl-functional siloxane cross-linking fluid can be selected from the group consisting of dimethylvinyl chain-stopped linear polydimethylsiloxane, dimethylvinyl chain-stopped polydimethyl-methylvinyl siloxane copolymer, tetravinyl-tetramethylcyclotetrasiloxane and tetramethyldivinyl-disiloxane. The hydrogen functional siloxane precursor fluid can be selected from the group consisting of tetra hydrotetra methylcyclotetrasil oxane, dim ethyl hyd rogen-cha instopped linear polydimethylsiloxane, dimethyl-hydrogen-chainstopped polydimethyl-methylhydrogen siloxane copolymer and tetramethyidihy- drodisiloxane.

The UV-curable acrylic-functional silicone release compositions of the present invention exhibit a desirable combination of properties: their syntheses are high-yield and utilize commercially available and relatively inexpensive inputs, they are shelf stable, and they undergo rapid cure when exposed to UV light in the presence of free-radical photoinitiators to form coatings with good release performance.

Acrylic-functional silicones have been described in U. S. Patents 2,956,044 (Merker) ; 3,650,811; 3,650,812 and 3,650,813 (Nordstrom et al.) but have not provided compositions suitable for the purposes herein. The Merker process utilizes chloromethyl-substituted organosilanes or silicones which are prepared by halogenation of methyl-silicones, or by reacting halosilanes with Grignard reagents followed by hydrolysis.

These processes are difficult and costly to adapt to large-scale productions, making chloromethyl silicone starting materials scarce and their subsequent acylation impractical. The Nordstrom syntheses involve reacting w-hydroxyalkyl-acrylates or methacrylates with silanol or alkoxy-containing polysiloxanes in the presence of condensation catalysts. Release compositions prepared according to these processes were unacceptably slow-curing and showed poor adhesion to substrates.

Experimental work herein with hydrosilation addition of ethylenically unsaturated acrylic-functional compounds, although affording UV radiation-curable compositions, likewise did not provide acceptable materials for the purposes of this invention. Acrylate or methacrylate esters of the formulae:

acrylates methacrylates where R is ethylenically unsaturated, will react with--SiH-containing polymers over a platinum catalyst.

However, because the acrylic group is itself a site of unsaturation, cross-linking occurs easily, as follows (R' issaturated):

allylacrylate (gel) In trials, a solid gel often resulted from hydrosilation.

It was determined that addition at the ally site was kinetically favoured, leading to trials which employed a twofold molor excess of the allylacrylate ester to preferentially derive an essentially uncrosslinked product having free acrylic sites. Although a high yield of fluid product was obtained, and the fluid had acceptable UV cure performance with a free-radical photoinitiator, the toxicity of the acrylate and methacrylate esters was seen as a major drawback. The esters are toxic by ingestion and give off highly irritating vapors. In addition, they are not readily available, expensive, and because of precautionary/safety measures entailed by their use, they would be expensive and impractical to adapt to industrial applications.

UV-curable acrylic-functional silicone compounds were also prepared herein via treatment of epoxyfunctional silicones with acrylic acid, based on the well-known ability of may acids to open the oxirane ring.

Accordingly, acrylic-functional silicones were prepared by reacting acrylic acid with an epoxy-silicone prepared by hydrosilation addition of 2, 6-dimethyl-2, 3-epoxy-7-octene to an =-SiH-containing fluid (see Examples 5 and 9, infra). This reaction can be illustrated as follows :

UV-curable release grade acrylic-functional polysiloxanes may be prepared in this manner; however, syntheses using these expensive epoxy-functional monomers, which are themselves UV-curable and within the scope of this invention, are regarded as inefficient.

The preferred acrylic-functional silicone compositions of the present invention are prepared by a step-wise process comprising (1) hydrosilation addition of an alkene halide to aSiH-containing polymer, followed by (2) reaction of the product with an OH-containing acrylate or methacrylate monomer, as illustrated below :

In the above formula, R is hydrogen or methyl and R'has been found to be limite, in the preparation of acrylic-functional silicones of this invention, to

Hencethe acrylate inputs in the preferred process for preparing acrylic-functional silicones must be selected from acrylic acid, methacrylic acid, hydroxyethylacrylate, and hydroxyethylmethacrylate. Acrylic acid is preferred. Also, as indicated by the formulae, the alkene halides suitable for these syntheses are limited to allylchloride and methallylchloride. Methallylchloride is preferred.

Acrylic-functional silicones produced according to this stepwise process offer the advantages of inexpensive starting materials, adaptabilityto large-scale operation and storage stability. The latter property is due to the separation of the acrylic function from direct bonding with silicon by one or more carbon atoms.

Hydrolysis in the presence of water would be a side-effect of acrylation of silicon halides, as illustrated below.

5 10 15 20 25 30 35 40 45 50 55 The product of (Vll) would be prone to hydrolysis :

UV-curable acrylic-functional silicone compositions can be made by combining the above-described acrylic-functional silicones with a catalytic amount of a free-radical-type photoinitiator which will effectively initiate crosslinking or self-condensing of the acrylic groups contained in the composition. Such free-radical photoinitiators include, among others, benzoin ethers, a-acyloxime esters, acetophenone derivatives, benzil ketals, and ketone amine derivatives. Preferred examples of these photoinitiators include ethyl benzoin ether, isopropyl benzoin ether, dimethoxyphenyl acetophenone and diethoxy acetophenone.

Epoxy-functional silicones can be made UV-curable by combination with a catalytic amount of an onium salt photoinitiator. Suitable photoinitiators for epoxy-silicone compositions are the onium salts having the formulae: R, i-MXn- f33S MXn- R3Se+ MXn R4P+ MXn R4N-MX,,- where radicals represented by R can be the same or different organic radicals from 1 to 30 carbon atoms, including aromatic carbocyclic radicals of from 6 to 20 carbon atoms which can be substituted with from 1 to 4 monovalent radicals selected from C(1-8) alkoxy, C(1-8) alkyl, nitro, chloro, bromo, cyano, carboxy, mercapto, etc. and also including aromatic heterocyclic radicals including, e. g. pyridyl, thiophenyl, pyranyl, etc.; and MXn-is a non-basic, non-nucleophilic anion, such as BF4-, PF6-, AsF6-, SbF6-, SbCI6-, HS04-, Cl04-, and the like.

Bis-diaryl iodonium salts, such as bis (dodecyl phenyl) iodonium hexafluoroarsenate and bis (dodecyl phenyl) iodonium hexafluoroantimonate, are preferred.

The amount of catalyst employed is not critical, so long as proper polymerization is effected. As with any catalyst, it is preferable to use the smallest effective amount possible ; for the purposes herein, catalyst levels of from about 1%-5% by weight have been found suitable.

The silicone compositions having both epoxy and acrylic functionality which are contemplated by the present invention are not crosslinked mixtures of discrete epoxy and acrylic monomers or prepolymers, ratherthe epoxy and acrylate (or methacrylate) groups are bonded to the same siloxane chain in a linear silicone polymer. The compositions contain units having the general formula :

where R is hydrogen or Co 3) alkyl and G is, independently, C (1 3) alkyl, an epoxy-functional organic radical of from 2 to 20 carbon atoms, or an acrylic-functional organic radical of from 2 to 20 carbon atoms.

Epoxy-functional organic radicals may be linear or cyclic including, for example, alkylhexeneoxides. As with the acrylic-functional silicones described previously, the acrylic units of the present dual-functional polymers may be formed in several ways and are most storage stable when the acrylic moiety is separated from the siloxane chain by one or more carbons.

Preferred epoxy-and acrylic-functional polysiloxanes are terpolymers having all of the following polymeric units in the same molecule :

where E signifies an epoxy-functional radical and A signifies an acrylic-functional radical. The most preferred terpolymer has

the formulaCH cxn oc x,, c=o /CHg 0 H C O /Cgx 3 CH-CH CH-CH H2 CH CH CH 0 H sio sic s si 0 CH3 CH3 \ CH3 \ CH3 CH3 CH3 CH3 x y z where x, y and z are positive integers from 1 to 1,000.

The epoxy-acrylic-functional polysiloxanes of the present invention are best prepared by hydrosilation addition of an epoxy-functional compound to a--SiH-containing silicone polymer, followed by hydrosilation addition of an w-halogen-containing olefin, followed by acrylate substitution at the halogen site in the presence of pyridine to yield the desired dual-functional polymer having pyridine hydrochloride precipitate.

It is desirable to monitor the level ofSiH-functionality during the synthesis so that the separate epoxy addition and halo-olefin addition will both have the necessary reactive sites on the silicone chain. This also allows control of the ratio of epoxy-functionality to acrylic-functionality. For example, by allowing 75% of the reactive--SiH sites to be substituted with epoxy groups, and substituting the remainder with an acrylic function, a 3-1 molar ratio of epoxy-functionality to acrylic-functionality can be obtained. This becomes important in view of the curing characteristics of these functional groups, described in detail below.

Suitable epoxy-functional compounds for use in the preparation of the dual-functional polysiloxanes contemplated herein, include all of the epoxy monomers discussed previously. Limoneneoxide is preferred.

In forming the reactive halogen site on the siloxane polymer (for later acrylate addition), any -halogen-containing olefin which will undergo hydrosilation and subsequently react with sources of acrylic-functionality is contemplated. These include allylbromide, 6-iodo-n-hexene, methallylchloride, and the like. Methallylchloride is most preferred.

Sources of acrylic functionality suitable for the preparation of the dual-functional polymers herein are hydroxy-functional acrylates, such as 2-hydroxyethylacrylate, pentaerythritol triacrylate, acrylic acid, methacrylic acid, 2-hydroxyethylmethacrylate and the like. Acrylic and methacrylic acid are preferred.

The epoxy-and acrylic-functional silicones of the present invention can be cured to adhesive release coatings when exposed to ultraviolet radiation in the presence of catalytic amounts of the aforementioned onium salt catalysts, or the aforementioned free-radical photoinitiators, or (most preferably) both types of photoinitiators. It has been found that not only will the dual-functional polymers of this invention cure more rapidly when combined with a dual catalyst system, but compositions having only epoxy functionality show faster cure and improved release characteristics when cured in the presence of both cationic onium salt photoinitiators and free-radical-type photoinitiators.

Cure of the dual-functional siloxane polymers can be enhanced or controlled by judicious blending of the catalysts and control of the UV exposure time. For example, rapid complete cure of the terpolymer compositions evidently requires both the onium salt photoinitiator and the free radical photoinitiator. It follows that terpolymer compositions can be partially crosslinked by employing one photoinitiator without the other, leaving reactive epoxy or acrylate functionality present for other chemical processes of interest.

Simple experimentation with the levels of catalyst and specific catalysts used will direct persons skilled in this area to the optimum photoinitiator (s) for a particular use.

Cure performance and adhesion of the epoxy-containing compositions described herein may also be enhanced by the addition of epoxy monomers to the compositions. For example, addition of up to 10 parts of an aliphatic epoxy monomer for every 10 parts epoxysilicone fluid results in compositions exhibiting superior UV cure and anchorage on porous cellulosic paper as compared to epoxysilicone fluids without these"reactive diluents".

The epoxy monomers, which are simply mixed with the silicone polymer compositions before application to a substrate, include olefinic epoxy monomers such as limoneneoxide, 4-vinylcyclohexeneoxide, allylglycidyl ether, 7-epoxy-1-octene, vinylcyclohexenedioxide, bis- (2, 3-epoxycyclopentyl) ether, 3,4 epoxycyclohexylmethyl-3, 4-epoxycyclohexanecarboxylate, cresylglycidyl ether, butanedioldiglycidyl ether and the like. Mixtures of such epoxides are also suitable. The reactive diluents should be soluble in the epoxysilicone fluid/photoinitiator release composition, and judicious pairing of the polymeric epoxy functionality and epoxy monomer allows tailoring of performance to particular situations. For the purposes herein, where the epoxysilicone functionality is derived from limoneneoxide, preferred epoxy monomer reactive diluents are co-epoxy C 811) aliphatic hydrocarbons. A mixture of such monomers is available commercially as Vikoloxe 11-14 (Viking Chemical).

The UV-curable epoxy-and/or acrylic-functional silicone compositions of the present invention can be applied to cellulosic and other substrates including paper, metal, foil, glass, polyethylene coated Kraft paper (PEK), supercalendered Kraft paper (SCK), polyethylene films, polypropylene films and polyester films. A photo-initiated reaction will cure the epoxy-and/or acrylic-functional silicone compositions of the present invention to form an abhesive surface on the coated substrate. Inerting of the cure environment may be necessary with free-radical curing, since oxygen tends to inhibit this type of reaction.

In order that persons skilled in the art may better understand the practice of the present invention, the following examples are provided by way of illustration, and not by way of limitation.

Examples 1-3 Synthesis of (3- (3, 4 epoxy cyclohexyl) ethyl silicone fluids from 4-vinylcyclohexene Sample 1 33 parts by weight of vinylcyclohexene, 33 parts by weight of a 150 cps. dimethylvinyl-chainstopped polydimethylsiloxane fluid and 0.05 parts by weight of a platinum catalyst (chioropiatinic acid-octy) aicoho) complex) were dissolved in 300 parts by weight hexane. 300 parts by weight of a polydimethyl methylhydrogen siloxane copolymer (135 cps. viscosity) containing 7.3% methylhydrogen siloxy units, was slowly added to the stirring hexane solution. This reaction mixture was then refluxed at 73 C for 4 hours. 10 parts hexene were added, and the reflux continued 16 hours more. A clear, 500 cps.-(3, 4cyclohexenyl) ethyl-functional fluid product was obtained after stripping the solvent and unreacted vinylcyclohexene and hexene at 110 C under a vacuum Sample 1E (epoxidized) 200 parts by weight of the Sample 1 product were dissolved in 800 parts by weight dichloromethane and cooled to 3 C. 40 parts by weight of 40% peracetic acid in acetic acid solution with potassium acetate buffer (FMC Corp.) was added slowly to the stirring cooled solution. An exothermic reaction ensued which raised the reaction mixture's temperature approximately 20 C. The mixture was stirred, after addition of the peracid was completed, for an additional 18 hours at room temperature. The resulting solution was then shaken with sodium bicarbonate and anhydrous magnesium sulfate, filtered, and the filtrate shaken with an equal volume of a 4% aqueous KOH solution. The organic phase was collected, treated with anhydrous magnesium sulfate and filtered. Solvent was stripped off under vacuum at 75 C to yield approximately 130 parts by weight of a clear, 600 cps. viscosity fluid (about a 60% yield).

Sample 2 75 parts by weight of 4-vinylcyclohexene, 15 parts by weight of a dimethylvinyl-chainstopped polydimethyl siloxane fluid (150 cps.) and 0.05 parts by weight platinum catalyst were dissolved in 300 parts by weight toluene. 300 parts by weight of a 95 cps. polydimethylmethylhydrogen siloxane fluid containing 9.9% methylhydrogen siloxy units were slowly added to the toluene solution, the complete reaction mixture being then refluxed at 115'C for 4 hours. 10 parts by weight hexene were added, and the reflux continued 16 hours more until no unreacted SiH groups were detected by infrared analysis. This-(3, 4 cyclohexenyl) ethylfunctional fluid in toluene product was stored over anhydrous magnesium sulfate.

Sample 2E (epoxidized) 220 parts by weight of the Sample 2 product were combined with approximately 610 parts by weight of toluene. 0.27 parts by weight hexacarbonyl molybdenum (Alfa Inorganic Chemicals) and 0.4 parts by weight di-basic anhydrous sodium phosphate (NaHPO4) were added and the reaction mixture heated to reflux temperature at 110 C, at which point 100 parts by weight of an anhydrous 40% solution of tetrabutylhyd- roperoxide (TBHP) * was slowly added over one hour to the refluxing, stirring reaction mixture. The mixture was refluxed for another hour, then cooled to 30 C. 40 parts by weight anhydrous sodium sulfite were added and the reaction mixture stirred overnight. The product solution was filtered and the toluene removed under a vacuum at 60 C to yield about 120 parts by weight of a clear, amber-coloured, 700 cps.-(3, 4-epoxy cyclohexyl) ethyl siloxane fluid (approximately 90% yield).

*Prepared by azeotropic distillation of a mixture of commercially available 70% aqueous TBHP (Aldrich Chemical Company) and toluene. The water is extracted so as not to interfere with the epoxidation reaction.

Infrared examination of Samples 1 E and 2E confirmed that the epoxidation of unsaturated sites had taken place. This was further confirmed in that they cured readily when exposed to UV light in the presence of onium salt catalyst, as reported below.

Sample 3 (preparation of Eckberg et al. 717 patent) A control sample of- (3, 4-epoxy cyclohexyl) ethyl-functional silicone fluid was prepared by the conventional hydrosilation addition of 4-vinylcyclohexeneoxide to aSiH-functional fluid. This sample was prepared in the same fashion as Sample 2, except that an equimolar amount of 4-vinylcyclohexeneoxide was substituted for 4-vinylcyclohexene in the synthesis. The above epoxy-functional samples were evaluated for UV cure : 1. 5 parts by weight of bis (dodecylphenyi) iodonium hexafluoroantimonate catalystwere mixed with 100 parts by weight of the experimental Samples 1 E, 2E and 3. The samples were then coated onto 40-pound supercalendered Kraft (SCK) paper with a doctor blade. The coated papers were exposed to UV-radiation in a PPG UV Processor housing 2 Hanovia medium pressure mercury UV lamps, each generating 200 2 focused power. Cure was determined by qualitatively noting the presence and extent of smear and migration in the silicone coatings.

Rub-off occurs when a silicone coating fails to adhere to the substrate and can be rubbed off in little balls of cured silicone by gentle finger pressure. Smear is detected in an incompletely cured coating when a finger firmly pressed across the silicone film leaves an obvious permanent streak. Migration is detected by the Scotch' cellophane tape test. The coating is considered well cured and migration-free if a piece of No. 610 Scotch tape will stick to itself after having been first firmly pressed into the silicone coating, then removed and doubled back on itself. If a silicone coating is shown to be migration-free by means of the Scotchd tape test, it is considered to be a release coating because it adheres to the substrate with an adhesive force much greater than the adhesive force between the cured composition and the released aggressive Scotch tape.

These qualitative tests are universally employed to ascertain the completeness of cure in silicone paper release coatings.

Smear-and migration-free silicone coatings were considered cured to good release surfaces. Results of the UV valuation are noted below : Sample UVExposure (sec) Smear Migration 3 0.3 none none 3 0.1 slight moderate 1E 0.6 none none 1E 0.3 slight slight 2E 0.3 none none 2E 0. 1 slight none 2 10.0 (no cure) (no cure) It can be seen from these results that the epoxy silicones synthesized according to the present invention have the same cure performance as epoxy silicones prepared using vinylcyclohexeneoxide.

Examples 4-6 Synthesis of novel epoxy-functionalpolysiloxanes from epoxy monomers Sample 4 130 parts by weight of a 250 cps. dimethylvinyl-chainstopped polydimethylsiloxane fluid, 700 parts by weight of limoneneoxide (SCM Corp.), and 1 parts by weight of a platinum-octyl alcohol complex were added to 4000 parts by weight of toluene. 2600 parts by weight of a 150 cps. dimethylhydrogen- chainstopped polydimethyl-methylhydrogensiloxane copolymerfluid containing 8.7 weight percent =SiH groups were added slowly to the stirring mixture at 26 C over 1 hour. The reaction mixture was then refluxed at 120 C for 6 hours, at which point 580 parts by weight of n-hexene were added and refluxing continued for 10 hours more. The solvents were removed by heating under a vacuum to yield an 800 cps. fluid product containing about 17 weight percent limoneneoxide and 0.8 weight percent unreacted =SiH groups.

Sample 5 20 parts by weight of the vinyl-containing siloxane fluid of Sample 4,40 parts by weight of 2,6-dimethyl-2,3-epoxy-7-octene (DMEO; SCM Organics) and 0.05 parts by weight of the platinum catalyst used in Sample 4 were added to 200 parts by weight toluene. 150 parts by weight of a 95 cps. dimethyfhydrogen-chainstopped polydimethyl-methylhydrogen siloxane copolymerfluid containing 9.5 weight percent =SiH groups were added slowly to the stirring toluene solution. The complete reaction mixture was refluxed at 115 C for 15 hours, at which pount 10 parts by weight hexene were added and the refluxing continued for 5 more hours. Less than 0.6 weight percent unreactedSiH was detected. The solvents were stripped to yield a clear 300 cps. epoxysilicone fluid product containing about 19 weight percentfunctionalized DMEO.

Sample 6 5 parts by weight of the vinyl-containing fluid used above, 0.05 parts by weight of the platinum catalyst and 12 parts by weight 1,4-dimethyl-4-vinylcyclohexene-oxide (DVO; Viking Chemical Co.) were added to 100 parts by weight hexane. 50 parts by weight of the 90 cps. methylhydrogen fluid of Sample 5 were added slowly to the toluene solution. The complete reaction mixture was then refluxed for 6 hours, at which point 5 parts by weight hexene were added and refluxing continued for 15 hours more. The toluene and excess hexene were stripped to yield a clear 280 cps. fluid product containing about 18 weight percent DVCO.

Samples 4,5 and 6 are each"precrosslinked"poly-dimethyl-methylalkyl (epoxy) siloxane linear polymers, chainstopped by dimethyl-alkyl (epoxy) siloxy groups. These fluids are clearly different in structure from the - (3, 4-epoxycyclohexyl) ethyl-substituted polysiloxanes described above. The three samples were combined with 1.5 weight percent of bis (dodecylphenyl) iodonium hexafluoroantimonate cationic photoinitiator and coated onto polyethylene Kraft (PEK) paper, supercalendered Kraft (SCK) paper and Mylar, then exposed to UV radiation in a PPG model 1202 AN UV Processor housing two Hanovia medium pressure mercury UV lamps, each generating 200 watts/in focussed powerto evaluate cure performance. The exposed films were evaluated for rub-off, smear, migration and release properties using techniques well known to persons familiarwith release coating technology.

All the coatings cured to smear-and migration-free adhesive surfaces on all substrates in from 0.1 to 0.3 seconds UV exposure time, and none exhibited appreciable rub-off.

Laminates were prepared on silicone-coated SCK substrates by 0.3 seconds UV exposure followed by 6 mil coatings of an SBR rubber adhesive (No. 4950 ; Coated Products, Inc. ( cured on top of the silicone layer. A second sheet of uncoated SCK paper was firmly pressed onto the adhesive layer. Release performance was tested by pulling the SCK-SBR lamina from the SCK-silicone lamina at a 180 angle at 400 feet/min. The force required to separate two inch wide strips of the two lamina was recorded, and the following results observed: Sample Release (grams) 4 70-90 5 50-80 6 60-85 Aging of these aminates for 4 weeks at 140 F did not significantly effect release performance.

Example 7 Synthesis ofepoxy-functional silicone from vinylnorbornene Vinyinorborneneoxide (VNBO) was prepared via epoxidation of a vinylnorbornene (VNB) following the procedure of U. S. 3,238,227 (Tinsley). 14.2 parts by weight of VNBO were combined with 100 parts by weight of a 95 cps. dimethylhydrogensiloxy-chainstopped linear polydimethyl-methylhydrogensiloxane copolymer fluid containing 6.25 weight percentSiH groups and a small amount of a platinum catalyst (chloroplatinic acid-octyl alcohol complex). The reaction mixture was then refluxed in 100 parts by weight hexene for 18 hours. Solvents were stripped off under a vacuum to yield a 385 cps. epoxy-silicone fluid. No unreacted =SiH groups were detected on infrared analysis.

As a control, an epoxy-functional silicone fluid was prepared in the above fashion, except that 4-vinyl-cyclohexeneoxide (VCHO) was used instead of VNBO.

10 parts of each of the two fluids were mixed with 0.2 parts each of bis (dodecylphenyl) iodonium hexafluoroantimonate photoinitiator, then coated onto 40-pound supercalendered Kraft (SCK) paper with a doctor blade. The SCK sheets were exposed to UV radiation on a PPG model 1202 AN Processor housing 2 Hanovia medium pressure mercury lamps each operating at 300 watts/in2focussed power for approximately 0.5 second. Both coatings cured to smear-and migration-free abhesive surfaces.

Release performance of the coatings was determined by preparing laminates of epoxysilicone-coated SCK sheets with 10 mil films of Gelva 263 (Monsanto) aggressive acrylic adhesive. Release testing was carried out using a Scott tester as described above, with the following results: Silicone Coating Release (grams) VNBO 90-100 Control (VCHO) 30-40 Release in the 100-gram range against an aggressive adhesive is considered excellent performance. From these results it can be seen that VNBO is an alternative to VCHO as a starting material for epoxy-functional silicone release compositions, because it may be readily prepared from commercial ly-available vinylnorbor- nene.

Example 8 500 parts byweight of a 70 cps dimethylhydrogen-chainstopped linear polydimethyl-methylhydrogen siloxane copolymerfluid were dissolved in 500 parts by weight toluene. 126 parts byweight limoneneoxide and 25 parts by weight of a 3000 cps dimethylvinyl-chainstopped linear polydimethyl siloxane fluid were then added. The reaction mixture was catalyzed with 0.2 parts by weight of a platinum catalyst, then refluxed for 18 hours. UnreactedSiH groups were removed by reaction with hexene. Excess hexene and toluene were stripped under a vacuum at 150 C to yield 581 parts by weight of a 660 cps epoxy-functional silicone fluid.

20 parts by weight of the above product were dispersed in 80 parts by weight hexane with 0.3 parts by weight bis (dodecylphenyl) iodonium hexafluoroantimonate. This composition was coated onto 40-pound SCK stock with a No. 2 wire-wound rod, and then immediately exposed to UV radiation as described in Example 7. A smear-and migration-free abhesive surface was obtained after approximately 0.3 seconds.

0.5-0.6 pounds per ream of the silicone were coated onto substrate in this fashion. Release performance of this thin, even film was determined against a 5 mil coating of aggresive SBR adhesive as described in Sample 6. Results for several determinations were each less than 50 grams.

Comparative examplesA-D Synthesis of priorartacrylic-functional silicones (Nordstrom etal., U. S. 3,650,811J SampleA 81 parts by weight of a-(tris (ethoxy) silyl) ethyl-chainstopped linear polydimethyl siloxane fluid prepared by hydrosilation addition of vinyltriethoxy-silane to a dimethylhydrogen-chainstopped dimethyl fluid were mixed with 6 parts by weight hydroxyethyl acrylate, 0.1 parts by weight tetraisopropyltitanate and 0.5 parts by weight hydroquinone. This reaction mixture was heated, with stirring, to 140 C. After 3 hours, generation of 1.58 parts by weight ethanol was observed. The reaction mixturewasstirredatlOOC under a vacuum to provide a hazy yeliow 280 cps. fluid product. The generation of ethanol indicates that at least partial acylation of the siloxane fluid had occurred.

This composition was tested for release performance by mixing 5 parts by weight of the fluid product with 0.2 parts by weight of a benzoin ether photoinitiator (Trigonal 4 ! 1 ; Noury Chemical Corp.). This material was coated on SCK paper and exposed to a single H3T7 mercury vapor UV source in a nitrogen atmosphere at 6 inches until a smear-free cured surface was obtained (about 1 min. exposure time). The cured film was smear-free and migration-free, but was easily rubbed off of the substrate.

Sample B 56 parts by weight of a dimethylhydrogen-chainstopped linear polydimethyl-methylhydrogen siloxane fluid containing 12 weight percentSiH units and 0.05 parts by weight of a platinum catalyst (chloroplatinic acid-octyl alcohol complex) were dissolved in 200 parts by weight benzene. 10 parts by weight allylacrylate were added to this solution, and the reaction mixture was refluxed for 3 hours. At this point the reaction mixture rapidly increased in viscosity and a solid, useless gel was obtained.

Sample C 35 parts by weight of allylacrylate and 0.05 parts by weight of a platinum catalyst [grade 88257] were dissolved in 150 parts by weight hexane. 100 parts byweight of methylhydrogen fluid containing 17.6 weight percent =SiH units was added slowly to the stirring hexane solution. The complete reaction mixture was heated to reflux (80 C). An intractable solid gel formed within 1 hour, and the reactants were discarded.

Sample D ; rMolar excess of acrylic monomer) 37 parts by weight allylacrylate and 0.05 parts by weight of a platinum catalyst [grade 88034] were dissolved in 200 parts by weight toluene. 100 parts by weight of a methylhydrogen copolymer containing 9.9 weight percent---SiH groups were added slowlyto the stirring solution. The complete reaction mixture was heated to 65 C for 10 hours, then to 85 C for 6 hours, at which point no unreacted =SiH groups could be detected by infrared spectroscopy. The solvent and excess allylacrylate were stripped off under a vacuum to yield 120 parts by weight of a 443 cps. fluid product.

A release coating composition was prepared by adding 4 weight percent diethoxyacetophenone to the above product. This was coated as a thin film onto SCK substrates and cured as in Example 7, requiring 6 seconds'UV exposure. The resulting cured surface exhibited little or no smear or migration, but was easily rubbed off of SCK substrates.

Acylation of epoxy silicones 100 parts by weight of a 450 cps epoxy silicone copolymer incorporating 16 weight percent 2,6-dimethyl-2,3-epoxy-7-octene (Sample 5, above) were dissolved in 200 parts by weight toluene with 15 parts by weight acrylic acid. The reaction mixture was heated to 115 C under nitrogen for 90 minutes.

Toluene and excess acrylic acid were stripped off under a vacuum to yield 98 parts by weight of a hazy amber 633 cps fluid. The higher viscosity of the product is an indication that the opening of the oxirane ring occurred.

These reactions can be represented as:

Similar materials are disclosed in U. S. 4,293,678 (Carter, et al.), but the epoxy function is specifically limited to allylglycidyl ether or vinylcyclohexeneoxide adducts. The instant example demonstrates that preparation of a range of different acrylic-functional compounds is possible.

10 parts by weight of this product were mixed with 0.4 parts by weight diethoxyacetophenone photoinitiator and the mixture applied to SCK paper with a doctor blade. The coating cured to a smear-and migration-free abhesive surface after 7.5 seconds exposure in a PPG processor housing two medium pressure mercury vapor ultraviolet lamps each operating at 300 watts/in. 2.

Examples 10-14 2-step synthesis of acrylic-functional silicones Sample 10 35 parts by weight of allylchloride were dissolved in 300 parts by weight hexane with 0.05 parts by weight of a piatinum catalyst [grade 88257]. 300 parts by weight of an 80 cps. linear methylhydrogen silicone fluid containing 8.5 weight percent =SiH groups were added to the hexane solution. This mixture was refluxed at 70for20 hours, at which point no =SiH-functionality was detected. Hexane and excess allylchloride were removed under a vacuum to yield a 100 cps. fluid containing-chloro-propyl substitution. 150 parts by weight of this material were stirred with 15 parts by weight acrylic acid and 21 parts by weight triethylamine at 100 C for 30 minutes under nitrogen. Stripping unreacted materials and filtering offthe amine- hydrochloride provided a hazy fluid product of 620 cps. viscosity.

Sample 19 50 parts by weight allylchloride, 40 parts by weight vinyl-chainstopped silicone fluid with 0.05 parts by weight platinum catalyst were dispersed in 15 parts by weight toluene. 500 parts by weight of a methylhydrogen silicone fluid containing 6.2 weight percent =SiH groups were added to the toluene solution, which was refluxed for4 hours. Excess allylchloride was removed under a vacuum, along with sufficient toluene to increase the solids content of the product to about 50% by weight. 19 parts by weight of ss-hydroxyethylacrylate were added to 308 parts by weight of the product, followed by very slow addition of pyridine. Stripping and filtering the product yielded a 500 cps fluid.

Sample 12 This sample was prepared as in Sample 11, except that 2-hydroxyethylmethacrylate was substituted for 2-hydroxyethylacrylate in the synthesis to yield a methacrylate-functional silicone product.

Sample 13 This sample was prepared as in Sample 11, exceptthat all processing was carried out in 1 reaction vessel.

Sample 14 60 parts by weight methallylchloride and 0.05 parts by weight of a platinum catalyst were dissolved in 200 parts by weight toluene. 200 parts by weight of a 95 cps. methylhydrogen silicone fluid containing 9.9 weight percent =SiH groups were added slowly to the toluene solution. The reaction mixture was refluxed for 15 hours, at which point no reactive =SiH groups were detected. Excess methallylchloride was removed under vacuum, then 24 parts by weight acrylic acid and 33 parts by weight triethylamine were consecutively added to the reaction vessel. Following addition of the amine, the reaction mixture was heated to 113 C for 1 hour, then stripped and filtered. A clear yellow 217 cps. fluid product was obtained.

The examples were combined with small amounts of free-radical photoinitiators, coated on SCK paper substrates and cured in an inert atmosphere to give cured abhesive coatings. The cure performance is summarized as follows : Cure Time Sample Acrylic Function Photoinitiator (sec) 10-CH2CH2CH2OOCCH=CH2 5% Trigonal 14 3. 0 11-CH2CH2CH20CH2CH200CCH=CH2 5% Trigonal 14 1.5 12-CH2CH2CH20CH2CH2OOCC (CH3) =CH2 5% Trigonal 14 5.0 13-CH2CH2CH2OCH2CH2OOCCH=CH2 4% DEAP 1.5 14-CH2CH (CH3) CH2OOCCH=CH2 4% DEAP 1.5 The release performance was determined against a 6 mil coating of aggressive SBR adhesive as described previously. Cured films of the above samples had release values of 40-80 grams, which is considered "premium"retease.

Examples 15and 16 Preparation of epoxy-acrylic-functional polysiloxanes Sample 95 An epoxy-and acrylic-functional silicone terpolymer was prepared as follows.

200 parts by weight of a 300 cps. dimethylhydrogen-chainstopped linear polydimethyl-methylhydrogen siloxane copolymer fluid containing 8 weight percent methylhydrogen siloxane units were added to a reaction vessel. 40 parts by weight limoneneoxide and 0.1 parts by weight of a platinum catalyst (U. S.

3,814,730 (Karstedt), incorporated herein by reference) were added, along with 240 parts by weight toluene.

This reaction mixture was refluxed for 16 hours. Infrared analysis showed 2.5 weight percent methylhydrogen siloxy units remained unreacted. Approximately 11.16 parts by weight methallylchloride were added, and refluxing resumed for 30 minutes, at which time no unreacted =SiH groups were detected. Excess methallylchloride was removed by distillation. 6 parts by weight acrylic acid were then added to the reaction vessel, followed by slow dropwise addition of 8 parts by weight pyridine to the stirring solution. A hazy precipitate formed as the pyridine was added. Solvent and excess amine were removed under a vacuum at 150 C. 206 parts by weight of a 2970 cps. fluid were obtained. Analysis revealed that 11.7 weight percent limoneneoxide and 3.35 weight percent acrylic acid functionality were included in the polymer composition.

The foregoing synthesis can be illustrated as follows.

CH3 CH 3 CH 3 H5i0 Si0 Si0 SiH + I I I' CH3 CH x CH3 y CH3 Put A CH3 H CH CH 1 3 1 1 3 1 3 'CH CH-w\. CHA\CH-/y CH 3 STEP 1 STEP 2 + ci Pt A ' + APC1 O Si0 Si0 Si0 5i0 Si C1 CH3 CH3 w CH3 z CH3 y CH3 STEP 2 STEP 3 0 + pyridine + J (-3 1. 3 TH3 O < ~ S iO HW IH < W CH CH W CH Z'A t'CH'/ 3 3 3 3 3 +HC 1 pyridine Sample 16 200 parts by weight of a 90 cps dimethylhydrogen-chainstopped polydimethyl-methylhydrogen siloxane copolymer fluid containing 10.5 weight percent methylhydrogen siloxy units were dispersed in 250 parts by weight toluene. 53 parts by weight limoneneoxide and 0. 1 parts by weight of the Karstedt catalyst (Example 15) were then added. The reaction mixture as refluxed for 16 hours. Consecutive reactions of methallylchloride and acrylic acid/pyridine as described in Example 15 yielded a 560 cps terpolymer fluid containing 16.7 weight percent limoneneoxide-functional units and 3.2 weight percent acrylic-functional units, or an oxiranelacrylic molar ratio of 3.8/1.

Three release coating compositions were prepared using Sample 16, as follows: Parts by weight Parts by Weight Parts by Weight Diethoxy- Coating Terpolymer (C2H25PhJ2lSbF6 acetophenone 16A 10 0.2 16B 10 0.2 0.5 16C 10-0.5 These mixtures were coated on 40-pound SCK paper and cured as in Example 9, with the following results : Coating Cure Time (sec) Description A 0.3 slight migration B 0.1 excellent anchorage C 0.3 very poor anchorage Example 97 200 parts by weight of a 70 cps dimethylhydrogen-chainstopped polydimethyl-methylhydrogen siloxane copolymer fluid containing 10 weight percentSiH groups were added to a reaction vessel. 150 parts by weight toluene, 51 parts by weight limoneneoxide and approximately 0.1 part by weight platinum catalyst were added and the mixture refluxed at 120 C for 17 hours, at which point 2. 08 weight percent =SiH functionality remained. 10 parts by weight methallylchloride were added and refluxing resumed for an additional 1'/z hours. No unreacted=SiH groups were detected. Excess methallyl-chloride was removed by distilling 50 ml of solvent at atmospheric pressure. The solution was cooled to 30 C and 5.0 parts by weight of acrylic acid were added, followed by dropwise addition of 14.0 parts by weight of triethylamine. The complete reaction mixture was then stirred for 12 hours at room temperature. The dispersion was filtered and stripped of solvent, amine and low-boiling side products under a vacuum at 150 C to yield 197 parts by weight of a hazy yellow 440 cps fluid containing an oxirane/acrylate group ratio of 3.4/1.

To test cure performance, three release coatings were prepared using the above product: dual-functional Photoinitiator Sample silicone fluid PhC : OC (CH3) 20H* (Cl2H25Ph) 2lSbF6 17A 10 parts by weight 0.3 parts by weight 17B 10 parts by weight-0. 15 parts by weight 17C 10 parts by weight 0.3 parts by weight 0.15 parts by weight * free-radical-type catalyst, available as Darocuree 1173 (E. M. Chemicals) Each of the three compositions was coated on 40-pount SCK paper with a doctor blade, then cured using a PPG Model QC1202 UV Processor housing two Hanovia mercury vapor lamps each giving 300 watts/in2 focussed power. The following results were obtained: Sample Exposure Timefsec) Remarks 17A 1.5 slight smear, no migration 17A 0.3 smear, no migration 17A 0.15 smear, no migration 17A 0.08 not cured 17B 0.15 no smear, slight migration 17B 0.08 not cured 17C 0.08 no smear, no migration, excellent anchorage Release performance of this polymer was tested by preparing coating baths as follows : Photoinitiator Bath Silicone Fluid PhC : OC (CH3) OH (C,ZH25PHJ2/SbFs 17D 20 parts by weight 0.6 parts by weight 17E 20 parts by weight-0. 3 parts by weight 17F 20 parts by weight 0.6 parts by weight 0.3 parts by weight (the above ingredients dispersed in 80 parts by weight of hexane) 8"x 10"SCK sheets were coated from the D, E and F baths with a No. 2 wire-wound rod to provide depositions of approximately 0.5 Ibs/ream. The sheets were exposed to UV light for 0.3 seconds in a PPG Processor as described above. The cured coatings were then laminated with 5 mil layers of SBR adhesive and a second SCK sheet pressed on to the adhesive layer. 2"x 8"strips of the silicon-coated lamina were pulled away from the adhesive lamina at 180tat400feeUmin. using a Scott tester, which recorded the force (in grams) required to separate the lamina : Coating Release (g) 17D 460-520 17E 320-400 17F 130-150 From this example it is seen that the degree of cure may be made a function of the type of catalyst employed, and the catalyst blend may be tailored to provide a desired level of release.

Examples 18-19 Dual catalystsystem forrapid curing of epoxy-functionalsilicones An epoxy-functional silicone fluid composition containing 80% epoxy-functional fluid having 20 weight percent limoneneoxide reactivity and 20% VikoloxS 11-14 epoxy monomer was used to form the following two release coating compositions: Photoinitiator Sample Epoxysilicone Diethoxy- (C, 2H25Ph) 215bF6 + Vikolox 11-14 acetophenone 18 10 parts by weight 0 : 15 parts by weight 19 10 parts byweight 0.15 parts byweight 0.15 parts byweight The samples were each hand coated on 40-pound SCK sheets and exposed to UV radiation in a PPG Processor housing 2 UV lamps, each operating at 300 watts'in in an air or nitrogen environment. Minimum UV exposure time to achieve smear-free and migration-free adhesive coatings was recorded.

Sample Atmosphere Cure Time fsecJ 18 air 0.3 18 nez 0.3 19 air 0.3 19 Nz 0.075 Release performance of hand-coated (solventless) specimens was tested using nitrogen-cured samples in laminates prepared with 10 mil layers of GelvatD (Monsanto) acrylic adhesive. Release at different UV exposuretimeswere recorded on a Scotttester : Sample Release (grams) 0. 3 sec. 0.15 sec. 0. 08 sec.

18 120-140 150-175 160-190 19 120-140 100-130 100-130 Examples 20-22 Further trials similar to the Examples 18 and 19 were set up in order to test another free-radical photoinitiator, Trigonal 14 (Noury Chemical Co.), a benzoin ether compound. An epoxysilicone-Vikoloxe 11-14 blend similar to that used in Examples 18 and 19 was used.

Photoinitiator Sample Epoxysilicone TrigonaP 14 (Cl2H25Ph) 2lSbF6 Vikolox 11-14 20 10 parts by weight 0. 15 parts by weight 21 10 parts by weight 0.15 parts by weight 0.15 parts by weight 22 10 parts byweight 0.15 parts byweight The samples were coated and cured as in Example 18, with the following results : Sample Atmosphere Cure Time (sec.) 20 air 0.6 20 N2 0.6 21 air 0.6 21 N2 0.075 22 air > 3. 0 (no cure) 22 N2 > 3. 0 (no cure) Examples 23-24 A toluene solution of an epoxy-functional silicone fluid was prepared to test benzophenone, a crystalline solid at room temperature, as a free-radical photoinitiator in the dual catalyst system of this invention. 300 parts by weight of an 85 cps dimethylmethylhydrogen silicone fluid, 99 parts by weight limoneneoxide and 300 parts by weight toluene were mixed and refluxed 20 hours. UnreactedSiH groups were eliminated by reaction with hexene to yield 725 parts by weight of a limoneneoxide-functional polysiloxane in toluene. Half this product was stripped of solvent and designated Sample 23. The remainder was treated with 0.32 parts by weight benzophenone, which readily dissolved in the hexane solution. The solvent was then stripped and designated Sample 24. Both samples were diluted with 17 weight percent Vikoloxg 11-14 epoxy monomer as a reactive diluent, bringing the viscosity of the fluid samples to about 225 cps. No evidence of the benzophenone coming out of solution was observed over four months'storage at room temperature.

Samples 23 and 24 were tested for UV curability as in Examples 18-22 after 10 parts by weight of each was combined with 0.2 parts by weight of (C12H25Ph) lSbF6 ; with the following results: UV Exposure Sample Atmosphere Time Rsec) Remarks 23 air 0.6 cured-no smear, no migration 23 air 0.3 smears, migrates 24 air 0.6 cured-no smear, no migration 24 air 0.3 smears, migrates 23 N2 0.3 smears, migrates 24 N2 0.07 cured-no smear, no migration Examples 25-28 Trials similar to Examples 23 and 24 were performed to test the efficacy of three other free-radical compounds:

"DarocureX 1173" (E. M. Chemicals) "Irgacur 651" (Ciba Geigy) "IrgacureX 184" (Ciba Geigy) Four portions of a limoneneoxide-functional silicone fluid (the same limoneneoxide-silicone fluid described in Examples 23-24) in toluene were prepared. To each of three portions were added 0.15 weight percent of Darocure 1173, Irgacure 651 and Irgacure 184, respectively, to form Samples 25,26 and 27.

Sample 28, containing no free-radical photocatalyst was maintained as a control. All four samples were stripped under a vacuum at 150 C to yield four fluids of approximately 600 cps. No reactive diluents were added in these examples.

Cure performance was tested in the same manner as Examples 23-24.0.15 parts by weight of bis-dodecylphenyl iodonium hexafluoroantimonate were added to 10 parts by weight of the four samples.

After coating on SCK stock and curing in a PPG Processor as described above, the following results were observed: Exposure Sample Atmosphere Time tsec) Remarks 25 air 1.5 cured-no smear, no migration 25 air 0.3 smear, migration 25 N2 0.075 cured-no smear, no migration 26 air 0.6 cured-no smear, no migration 26 air 0.3 smear, migration 26 N2 0.15 cured-no smear, no migration 26 N2 0.075 smear, migration 27 air 0.6 cured-no smear, no migration 27 air 0.3 smear, migration 27 N2 0.06 cured-no smear, no migration 28 air 0.6 cured-no smear, no migration 28 air 0.3 smear, migration 28 N2 0.3 smear, migration The cure-enhancing effect of free-radical photoinitiators can be seen to lead to a five to ten-fold improvement in the cure rate when an inert cure environment is present. The faster production benefits made possible by these increased cure rates can make up for the added expense of inerting the curing chambers.

Examples 29-32 Epoxysilicones enhanced by addition of aliphatic epoxy monomers An epoxy-functional silicone fluid was prepared in the following manner: 40 parts by weight limoneneoxide were dispersed in 160 parts by weight toluene. To this were added 200 parts by weight of a 170 cps dimethylhydrogen-chain-stopped linear polydimethyl-methylhydrogen siloxane copolymer fluid having 8 weight percent =SiH groups and 10 parts by weight of a 250 cps dimethylvinylchainstopped polydimethyl siloxane fluid. This mixture was catalyzed with 0.05 parts by weight of a platinum catalyst, then refluxed at 120 C for six hours. Hexene was added to react with the remaining =SiH functions, followed by resumption of reflux for 16 hours. Hexene, and solvents were stripped under a vacuum to yield 217 parts by weight of a 1730 cps epoxy-functional dimethyl silicone copolymer fluid containing about 14 weight percent limoneneoxide functionality.

This reaction product was combined with varying amounts of an epoxidized efin, Vikolox 11-14 (Viking Chemical Co.) having the formula :

where n is an integerfrom 8 to 11. Vikolox 11-14 is a mixture of epoxides of from 11 through 14 carbons. The following coating samples were prepared to examine cure performance: EpoxyMonomer Viscosity Sample Epoxysilicone (Vikolox) (Cl2H25Ph) 2lSbF6 (CPS) 29 100 parts by weight 1. 5 parts by weight 1730 30 90 parts by weight 10 parts by weight 1.5 parts by weight 820 31 80 parts by weight 20 parts by weight 1.5 parts by weight 465 32 70 parts by weight 30 parts by weight 1.5 parts by weight 275 The samples were coated onto 40-pound SCK paper with a doctor blade, then exposed for 0.3 seconds to UV radiation from two Hanovia medium pressure mercury vapor lamps, each providing 300 watts/in2 focussed power, housed in a PPG 1202 UV Processor, then examined for smear, migration and rub-off: Sample Smear Migration Rub-off 29 slight moderate severe (rub-offwith light pressure) 30 slight moderate moderate 31 slight slight slight 32 slight slight none Laminates prepared as in previous examples using Gelvae 263 acrylic adhesives (Monsanto) and SCK paper, were cut into 2"x 9"tapes, then pulled apart at 400 feet/min. using a Scott tester. The following release data were generated (Adhesive Transfer measures any adhesive sticking to silicone/SCK lamina pulled away) : Sample Release (g) Adhesive Transfer 29 140-170 yes 30 100-150 no 31 170-140 no 32 120-140 no Examples 33-37 An epoxysilicone fluid of approximately 9000 cps was prepared as described in Examples 29-32. This material was blended with Vikoloxe 12 monomer (epoxidized 1-dodecene) to furnish the following coating compositions: Viscosity Sample Epoxysilicone EpoxyMonomer (C2H25PhJ2ISbFs (cpsJ 33 100 parts by weight 1. 5 parts byweight 9000 34 90 parts by weight 10 parts by weight 1.5 parts by weight 4800 35 80 parts by weight 20 parts by weight 1.5 parts by weight 2260 36 70 parts by weight 30 parts by weight 1.5 parts by weight 1140 37 60 parts by weight 40 parts by weight 1.5 parts by weight 610 The samples were coated and cured as in Examples 29-32, with the following results : Sample Smear Migration Rub-off 33 slight slight severe 34 slight slight moderate 35 very slight slight slight 36 slight slight slight 37 moderate moderate trace Release performance was tested against an aggressive SBR adhesive in laminates, with the following results: Sample Release (grams) Adhesive Transfer 33 40-100 yes 34 40-90 no 35 80-140 no 36 220-270 no 37 370-450 no Examples 37-39 A 960 cps epoxy-functional silicone fluid was synthesized as described in Examples 29-37. This product was blended with Vikolox# 11-14 epoxy monomer, the blends cured and evaluated on 40-pound SCK paper as in previous examples. The results are shown below : Viscosity Sample Epoxysilicone EpoxyMonomer (CZH25PhJzlSbFs cps 37 100 parts byweight 1. 5 parts by weight 960 38 90 parts by weight 10 parts by weight 1.5 parts by weight 500 39 80 parts by weight 20 parts by weight 1.5 parts by weight 290 Sample Smear Migration Rub-off Release (g) 37 slight moderate moderate 70-100 38 none moderate slight 60-90 39 none slight none 110-140 Coating of solventless silicone release coatings onto rolled substrates by offset rotogravure is best accomplished with fluid viscosities in the range of 300-1000 cps. Also, compositions with acceptable cure, high release values, but no adhesive transfer (see Sample 36) might be useful for controlled release applications. It can be seen from the foregoing data that the use of reactive diluents can be helpful in achieving either or both of the goals of ease of application and controlled release.

Examples 40-46 A 660 cps limoneneoxide-functional silicone fluid was synthesized as described in the previous 3 sets of examples, then combined with a variety of epoxy monomers as follows : Sample Epoxysilicone EpoxyMonomers* {C, 2H25Ph) 21SbF6 40 10 parts byweight (none) 0.15 parts byweight 41 8.5 parts by weight 1.5 parts by weight 0.15 parts by weight Vikolox 11-14 42 8.5 parts by weight 1. 5 parts by weight 0. 15 parts by weight CY-183 43 8.5 parts by weight 1.5 parts by weight 0. 15 parts by weight DY-023 44 8.5 parts by weight 1.5 parts by weight 0.15 parts by weight Epoxide 7 45 8.5 parts by weight 1.5 parts by weight 0.15 parts by weight Epoxide 8 46 8.5 parts byweight 1.5 parts byweight 0.15 parts byweight BDGE

*Vikolox 11-14 = CH3 (CH)-CH-CH2, n=8-11 (Vikingzou 0 CY-183 (Ciba-Geigy) 0 0 DY-023 = CH3 < (Ciba Geigy) (cresylglycidyl ether) Epoxide7 C (g-10) H (17-21) O (CibaGeigy) Epoxide 8 = C (12-14) H (25-29) (Ciba Geigy) The above samples were coated on SCK paper and cured as in previous examples for 0.3 seconds. The following results were observed: Sample BlendAppearance Cure Performance 40 hazy slight smear & migration, easily rubbed off substrate 41 clear cured-no smear, migration or rub-off 42 opaque no cure 43 opaque poor cure-smearing, migration 44 clear cured-no smear, migration or rub-off 45 clear cured-no smear, migration or rub-off 46 opaque no cure From Examples 42,43 and 46 it is seen that the reactive diluents must be miscible with both the epoxysilicone fluid and the onium salt photocatalyst.

Silicone release coating baths were prepared from the 3 successful coatings above for release performance evaluation, as follows : Sample Epoxysilicone Diluent (Cl2H25Ph) 2lSbF6 Hexane 40A 20 parts by weight none 0.3 parts by weight 80 parts by weight 41A 17 parts by weight 3 parts by weight 0.3 parts byweight 80 parts by weight Vikolox 11-14 44A 17 parts by weight 3 parts byweight 0.3 parts by weight 80 parts byweight Epoxide 7 45A 17 parts by weight 3 parts by weight 0.3 parts by weight 80 parts by weight Epoxide 8 These samples were applied to 40-pound SCK stock with a No. 2 wire-wound rod to give thin, even coating depositions of 0.5-0.6 Ib/ream. UV exposure for 0.3 seconds cured all coatings, with 40A showing some rub-off. Laminates were prepared using an aggressive SBR adhesive. 2"x 8"strips of the epoxysilicone/SCK lamina were pulled away from the adhesive/SCK lamina at 180 at 400 feet/min, generating the data below : Coating Release (g) Adhesive Transfer 40A 35-50 no 41A 30-45 no 44A 30-45 no 45A 30-50 no It will be obvious to those skilled in the art that cure and substrate adhesion of acrylic-functional silicones (such as described in Examples 10-14) and dual-functional acrylic-epoxysilicones (such as described in Examples 15 and 16) are also improved by the use of silicone-soluble epoxy monomers, so long as onium salt catalysts (such as (Ca2H25Ph) 21SbF6) are included in the coating formulation.

Claims (28)

Obviously, modifications and variations in the present invention are possible in light of the foregoing disclosure. It is understood, however, that any incidental changes made in the particular embodiments of the invention as disclosed are within the full intended scope of the invention as defined by the appended claims. CLAIMS

1. An organopolysiloxane having acrylicfunctionality prepared by hydrosilation addition of a hydrogen functional polysiloxane fluid and an alkene halide selected from allyl chloride and methallyl chloride, followed by reaction of the product of said hydrosilation with a hydroxy-functional acrylate selected from acrylic acid, methacrylic acid, hydroxyethyl acrylate and hydroxyethyl methacrylate, in the presence of a tertiary amine.

2. A polysiloxane as claimed in Claim 1 wherein the alkene halide is methallyl chloride, the acrylate is acrylic acid and the tertiary amine is triethylamine.

3. An ultraviolet radiation-curable polysiloxane release coating composition comprising (A) an acrylic-functional polysiloxane as claimed in Claim 1 or 2, and (B) a catalyst amount of a free-radical photoinitiator.

4. A composition as claimed in Claim 3 wherein component (B) additionally contains a catalytic amount of an onium salt and said composition contains an additional component (C) of an amount of epoxy-functional monomers sufficient to enhance the cure of said composition.

5. An organopolysiloxane having epoxy and acrylic functionality prepared by (1) performing a hydrosilation addition of a hydrogen-functional polysiloxane and an epoxy olefin compound without reacting all of the hydrogen-silicon groups in said polysiloxane ; (2) reacting the product of step (1) with an o,-halogen-containing olefin by hydrosilation addition; and (3) reacting the product of step (2) with an hydroxy-functional acryiate compound in the presence of pyridine.

6. A polysiloxane as claimed in Claim 5 wherein the epoxy olefin is limoneneoxide, the o-halogen- containing olefin is methallyl chloride and the hydroxy-functional acrylate compound is acrylic acid.

7. An ultraviolet radiation-curable polysiloxane release coating composition comprising (A) a polysiloxane product as claimed in Claim 5, and (B) a catalytic amount of a photoinitiator comprising (i) an onium salt having the formula: R2l+MXn-, or R3S+MXn-, or R3Se'MXn-, or R4P'MXn-, or R4N+MXn-, where R can be the same or different organic radical, including aromatic carbocyclic and heterocyclic radicals, of from 1 to 30 carbon atoms, and MXn-is a non-basic, non-nucleophilic anion, (ii) a free-radical photoinitiator, or (iii) a combination of (i) or (ii) above.

8. A polysiloxane as claimed in Claim 7 wherein the epoxy olefin is limoneneoxide, the w-halogen- containing olefin is methyallyl chloride, the hydroxy-functional acrylate is acrylic acid and the photoinitiator component (B) is a combination (iii) of bis (dodecylphenyl) iodonium hexafluoroantimonate and diethoxyacetophenone.

9. A polysiloxane as claimed in Claim 7 wherein the epoxy olefin is limoneneoxide, the-halogen- containing olefin is methallyl chloride, the hydroxy-functional acrylate component is acrylic acid and the photoinitiator component (B) is a combination (iii) of bis (dodecylphenyi) iodonium hexafluoroantimonate and dimethylhydroxyacetophenone.

10. A composition as claimed in Claim 7 wherein the photoinitiator (B) is a combination (iii) of said onium salt and free-radical photoinitiator, and the composition contains an additional component (C) comprising an amount of epoxy-functional monomers sufficient to enhance the cure of said composition.

11. A process for preparing an organopolysiloxane having acrylic functionality comprising the steps: (1) reacting an alkene halide selected from aisy) chloride and methallyl chloride with a hydrogen-functional siloxane compound in the presence of a small amount of precious metal catalyst ; (2) recovering a chlorinated siloxane compound and reacting it with a hydroxy-functional acrylate selected from acrylic acid, methacrylic acid, hydroxyethylacrylate and methacrylate in the presence of a tertiary amine; and (3) recovering acrylic-functional polysiloxane.

12. A process as claimed in Claim 11 wherein the alkene halide is methallyl chloride, the acrylate is acrylic acid and the tertiary amine is triethylamine.

13. A process for preparing an organopolysiloxane having epoxy and acrylic functionality comprising the steps: (1) reacting an epoxy olefin compound with a hydrogen-functional polysiloxane in the presence of a small amount of a precious metal catalyst, for a period sufficient to react some but not all of the hydrogen-siiicon groups; (2) recovering an epoxy-functional, hydrogen-functional polysiloxane product, and reacting it with an w-halogen-containing olefin in the presence of a precious metal catalyst ; (3) recovering an epoxy-functional, halogenated polysiloxane and reacting it with a hydroxy-functional acrylate in the presence of pyridine; and (4) recovering a polysiloxane having epoxy and acrylic functionality.

14. A process as claimed in Claim 13 wherein the epoxy olefin compound is limoneneoxide, w-halogen-containing olefin is methallyl chloride and the hydroxy-functional acrylate is acrylic acid.

15. A process for preparing an ultraviolet radiation-curable silicone release coating composition having both epoxy and acrylic functionality comprising the steps: (1) reacting an epoxy olefin compound with a hydrogen-functional polysiloxane in the presence of a small amount of a precious metal catalyst for a period sufficient to react with some but not all of the hydrogen-silicon groups; (2) recovering an epoxy-functional, hydrogen-functional polysiloxane product and reacting it with an -halogen-containing olefin in the presence of a precious metal catalyst ; (3) recovering an epoxy-functional, halogenated polysiloxane and reacting it with a hydroxy-functional acrylate presence of pyridine; (4) recovering a polysiloxane having epoxy and acrylic functionality ; and (5) adding a small amount of a photoinitiator comprising (i) an onium salt having the formula: R2i+ MXn-, or R3St MXn-, or R3Se+ MXn-, or R4P+ MXn-, or R4N + MXn where R can be the same or different organic radical, including aromatic carbocylic and heterocyclic radicals, of from 1 to 30 carbon atoms, and MXn-is a non-basic, non-nucleophilic anion, or (ii) a free-radical photoinitiator, or (iii) a combination of (i) and (ii) above.

16. A process as claimed in Claim 15 wherein the epoxy olefin is selected from 4-vinylcyclohexeneoxide, 1,4-dimethyl-4-vinylcyclohexeneoxide, 2,6-dimethyl-2,3-epoxy-7-octene and limoneneoxide; the w-halogen- containing olefin is selected from allyl bromide, 6-iodo-n-hexene, and methallyl chloride, the hydroxyfunctional acrylate is selected from 2-hydroxyethyl acrylate, pentaerythritol triacrylate, acrylic acid, methacrylic acid and 2-hydroxy-ethyl methacrylate.

17. A process as claimed in Claim 16, wherein the photoinitiator is an onium salt of the formula : R2l+MXn-, or R3S+ MXn-, or R3Se+ MXn-, or R4P+ MXn-, or R4N+MXn-, where R can be the same or different organic radical, including aromatic carbocyclic and heterocyclic radicals, of from 1 to 30 carbon atoms, and MXn-is a non-basic, non-nucleophilic anion.

18. A process as claimed in Claim 16 wherein the photoinitiator is a free-radical photoinitiator.

19. A process as claimed in Claim 16 wherein the photoinitiator is a combination of (i) an onium salt of the formula R21t MXn-, or R3S+ MXn-, or R3Se+ MXn-, or R4P+ MXn-, or R4N+ MXn, where R can be the same or different organic radical, including aromatic carbocyclic and heterocyclic radicals, of from 1 to 30 carbon atoms, and MXn-is a non-basic, non-nucleophilic anion, and (ii) a free-radical photoinitiator selected from benzoin ethers, a-acyloxime esters, acetophenone derivatives, benzil ketals, and ketone amine derivatives.

20. A process as claimed in Claim 15 wherein the polysiloxane product recovered after step (4) is a polysiloxaneterpolymer having the formula:

where E is an epoxy-functional organic radical, A is an acrylic-functional and x, y and z are, independently, positive integers from 1 to 1,000.

21. A process as claimed in Claim 20 wherein said terpolymer is combined with an onium salt photoinitiator having the formula : R21+ MXn-, or R3S+MXn-, or R3Se+ MXn-, or R4P+ MXn-, or RQN+ MX"-, where R can be the same or different organic radical, including aromatic carbocyclic and heterocyclic radicals, of from 1 to 30 carbon atoms, and MXn-is a non-basic, non-nucleophilic anion.

22. A process as claimed in Claim 20 wherein said terpolymer is combined with a free-radical photoinitiator.

23. A process as claimed in Claim 20 wherein said terpolymer is combined with a photoinitiator comprising (i) an onium salt having the formula: RMXn-. or R3S+MXn-, or R3Se+ MXn-, or R4P+MXn-, or R4N-MXr,-, where R can be the same or different organic radical, including aromatic carbocylic and heterocylic radicals, of from 1 to 30 carbon atoms, and MXn-is a non-basic, non-nucleophilic anion, and (ii) a free-radical photoinitiator.

24. A process as claimed in Claim 23 wherein the radicals represented by E

and the radicais represented by A are

25. A process as claimed in Claim 24 wherein the photoinitiator is a combination of a bis-diary iodonium salt and a free-radical photoinitiator selected from diethoxyacetophenone, dimethylhydroxyacetophenone, benzophenone, dimethoxyphenylacetophenone, and hydroxyisopropylphenone.

26. A process as claimed in Claim 25 wherein said photoinitiator is bis (dodecylphenyl) iodonium hexafluoroantimonate combined with diethoxyacetophenone.

27. A process as claimed in Claim 25, wherein said photoinitiator (B) is a combination (iii) of said onium salt and free-radical photoinitiator, and the process includes the additional step (6) of adding an amount of epoxy-functional monomers sufficient to enhance the cure of said composition.

28. A process as claimed in Claim 23 which includes the additional step (6) of adding an amount of epoxy-functional monomers sufficient to enhance the cure of said composition.