CA1180482A - Self bonding addition cured silicone systems - Google Patents

Abstract

SELF-BONDING ADDITION CURED SILICONE SYSTEMS

ABSTRACT OF THE DISCLOSURE

A self-bonding addition curing silicone system comprising a vinyl containing base polymer, a platinum catalyst, a hydride resin as a cross-linking agent and as the self-bonding additive an acryloxy silane or siloxane compound. Preferably the acryloxy compound is gamma methacryloxypropyltrimethoxysilane.
In the preferred process for preparing the composition, the acryloxy compound is first mixed with the hydride silicone resin before the rest of the ingredients are added or mixed into the composition.

Description

60SI~338 SELF-BONDING ADDITION CURED SILICONE SYSTEMS
Background Of The Invention The present invention relates to an SiH
Olefin platinum catalyzed addition silicone composition and more parkicularly the present invention relates to self-bonding Si~l Olefin platinum catalyzed compositions.
Si Olefin platinum catalyzed compositions are well known. Such compositions are also referred to as addition curing systems or compositions. Such compositions generally comprise a base vinyl containing polysiloxane polymer, a hydride cross-linking agent which can be either a hydride resin composed of monofunctional units and tetrafunctional units or a hydride resin composed of monofunctional units and tetrafunctiona] units and difunctional units or a hydride containing linear polysiloxane fluid. The adclition of the hydrogen in the hydride cxoss-linking agent to the vinyl of the polysiloxane so as to cure the system is carried out under the influence of a platinum catalyst. Many platinum catalysts have been developed for such a purpose particularly platinum complexes of aldehydes and alcohols or a platinum complex catalyst formed by reacting chloroplatinic acid with a vinyl containing polysiloxane~
There is also disclosed by the prior art that there may also be incorporated in such compositions resins containing vinyl substitution such as disclosed ?4~ .

~ 2 --in the patent of Frank J. Modic, U.S. Patent No.
3,436,366 - issued April 1,, 1969. It is disclosed in , ~ the foregoing patent that/may be incorporated in such SiH Olefin platinum catalyzed compositions or addition systems, fillers, such as fumed silica or precipitated silica or extending fillers. Such compositions are prepared by placing the ~inyl polysiloxane filler in one package and by mixing the hydride cross~linking agent by itself with or without filler and having the platinum catalyst with the vinyl siloxane which is present in a separate package. The composition is packaged or prepared into two components or two packages. When it is desired to cure the composition, the vinyl siloxane and the platinum catalyst is hrought together with the hydride and can be cured at room temperature to a silicone elastomer.
It has been found :that inhibitor compounds may be incorporated in such compositions so that they remain uncured at room temperature or can be cured in a relatively rapid pace at elevated temperatures such as temperatures above 100 and 150C. Examples of such inhibitors are for instance, triallylisocyanurate and hydroperoxy compounds as disclosed in the patent of William J. Bobear, U.S. Patent No. 4,061,~,09 - issued December 6r 1977. The inhibitor compounds of the Bobear patent allow the composit.ion to be packaged in a single package which without the curing of the composition for a period of 6 months to a year or more, and then by heating the composltion at elevated temperatures, the composition cures to a silicone elastomer. It should be noted that in the Bobear patent the hydroperoxide compounds are disclosed solely as inhibitor compounds.
The compositions which cure to a silicone elastomer result in good potting and encapsulation compositions, for the dieIectric properties of the addition cure silicone are aptly suited for these uses. However, the lack of adhesion of such compositions which are normally not adhesive results at times in the causing of the delamination of the encapsulated electronic components.
This results in subjecting the electrical components to moisture, vibration, and damage. There may result such heavy damage or destruction that electrical discharges can occur across coating voids resulting from the delamination of the encapsulant. The lack o adhesiveness o such addition cure silicone composition makes them admirably suited as molding compounds but is decidedly a disadvanta~e when such compositions are utilized to encapsulate or pot electrical components.
It should be noted that such addition cure silicone systems or silicone elastomers have outstanding properties such as optical clarityl tensile strength, elongation and tear properties, resistance to reversions, and high temperature.
The lack of adhesion of such addition cure silicone compositions is a decided disadvantage when such compositions are, for instance, to be applied for gasketing applications, glass cloth impregnation and silk screening applications. Primers may be utilized to improve the adhesion or resul-t in the desirable adhesion of the silicone cured elastomer to a substrate. However, such primers represent an additional step in the application of the system increasing the cost of the application of addition cure systems. Also such primers are hard to apply to complex shapes and in complex printing system~ such as the silk screening printing system. An example of a primer for condensation RTV compositions is to be found in Smith U.S. Patent No. 4,177,301 - issued December 4, 1979.
Recently in condensation curing RTV and in ~ 4 heat curable vulcanizable silicone rubber composition there has been developed self-bonding additives. For example, see the Canadian Patent application of Smith, DeZuba and Mitchell - Serial No. 359,263, disclosing the use of silyl maleates and fumerates and succinates to produce self-bonding condensation cured one-component room temperature vulcanizable silicone rubber compositions.
However, such self~bonding additives are useless in an addition cure system. One example of an attempt ~o to produce a viable self-bonding addition cure system is to be found in the patent of Ballard, U.S. Patent No~
3,527,655 - issued September 8, 1970. However, it did not produce enough self-bonding or adhesive properties in the composi~ion. ~nother more successful at-tempt is to be found in the Canadian Application Serial No.
325,063 - filed April ~, 1979, of Dujack and Hardman, entitled "Self-Bonding Silicone Rubber Compositions".
The Ballard patent discloses a vinyl alkoxy silane that is a self bonding addition system with such an additive which did not function satisfactorily in all cases. A more suitable self-bonding addition system was produced in the Hardman and DuJack application by utilizing a partial hydrolyzate of a vinyl triethoxy silane. However, such a system was not satisfactory as would be desired in that the self-bonding properties or adh~sion was not as good as would be desired, but nevertheless, was superior to that of the Ballard system.
Accordingly, there has been made a constant effort and a constant attempt to produce a self-bonding addit~on cure system and specifically for the production of a self-bonding addition cure RTV that could be utilized to produce gaskets on metal substrates and on plastic substrates and which could be u-tilized in various printing techniques. It should be noted that the silk screen printing methods are u-tilized to produce gaskets from various materials on various types of metal and plastic substrates. The purpose of the silk screening method is to print out a complex configuration. Machinery can be utilized to print a relatively simple configuration, but silk screening printing methods are utilized to produce gaskets of a complex configuration. As previously stated, the silk screening printing method comprises wherein a silk screen of a certain thickness is taken and everything but the shape of the gasket is varnished.
Then the composition that is desired to be printed is applied over the figure that is to be printed. Wiper blades force the composition through the silk screen in the exact thickness of the silk screen so that it comes through the silk screen and fall on the substrate in the exact figuration which it is desired that the composition be printed. This method results in the printing of complex configurations and shapes on various types of substrates. In order for the method to work, the composition has to have adhesion or self-bonding to the substrate. Accordingly, prior to the present invention, addition cure compositions could not be utilized in the silk screening method to produce a complex gasket on substrate such as a metallic, plastic and ceramic substrate.
Accordingly, it is one object of the present invention to provide for an addition cured silicone system which is self-bonding to metal, plastics and ceramic substrates.
It is another object of -the present inven~ion to provide for a process for producing addition cured silicone elastomers and systems which are self-bonding to metallic, plastic and ceramic substrates.
It is an additional object of the present invention to provide for an addition cured silicone system which can be utilized to print -with the silk screening method for printing of gaskets on a metallic, plastic or ceramic substrate.
It is still yet an additional object of -~he preserlt invention to provide for an article or laminate which is produced from a self-bonding addition cured silicone system.
It is still another additional object of the present invention to provide for a method for producing laminates and articles from a self-bonding silicone addition cured system utilizing a silk screen printing method.
These and other objects of the present invention are accomplished means of the disclosure set forth here and below.
Summary of the_Invention In accordance with the above objects, there is provided by the present invention a self-bonding addition curing silicone composition comprising a self-bonding addition curing silicone composition comprising (A) 100 parts by weight of a base vinyl containing dioryanopolysiloxane o a viscosity varying from 100 to 500,000 centipoise at 25C where the vinyl content varies from 0.04 to 1.5 percent by weight, the organo group is a monovalent hydrocarbon radical;
(B) from 1 to 500 ppm of platinum catalyst; (C) from .1 to 25 parts by weight of a hydride resin selected from the class consisting of resins having HR2SiO units and SiO2 units where the ratio of H+R to Si varies from 1.0 to 2.7 and resins having HR2Sioo 5units, SiO2 units and R2 -~iO units where the ratio oE H-~R+R
to Si varies from 1.2 to 2.7 where R is a monvalent hydrocarbon radical and Rl is selected from hydrogen and a monovalent hydrocarbon radical and (D) from 0.5 ~ ~ ~(3 ~

to 8 parts by weight of a self-bonding additive selected from the C~rm consisting of silanes of the formula, (1) 2 C - o R - Si (O R )3-a where R2, R , R5 are monovalent hydrocarbon radicals, R is a divalent hydrocarbon radical and a is a whole number 0 to 2, and siloxanes of the formula,

(2)~ C - O ~ Rb Si4-a1b _ a' where R2, R3 as defined where, R" is a monovalent hydrocarbon radical, al varies from 0.005 to 2.0, b varies from 1.0 to 2.5 and the sum of a+b varies from 1.005 to 3.0~ To increase the self-bonding properties of the composition, there may be added at least 400 parts per million of self-bonding promoter containing at least one hydroperoxy radical and rom 2 to 25 parts by weight based on 100 parts of the base polymer of a fumed silica iller treated with silazanes. It should be noted that in the process for forming such compositions the hydride resin must be mixed with the acryloxy compound first before the other compounds are mixed into the hydride resin or the acryloxy compounds. The preferred acryloxy compound is ~ -me~hacryloxypropyltrimethoxysilane. Other details of the respective present invention will be given below.
Descri.ption of The Preerred Embodiment The base vinyl containing diorganopolysiloxane polymer may be any vinyl containing diorganopolysiloxane polymer that is utilized in SiH Olefin platinum catalyzed compositions. The vinyl may be vinyl in the chain or the vinyl may be on the siloxy terminal units or it may be both in t:he chain and on the siloxy terminal unitsO Preferably the base vinyl containing diorganopolysiloxane polymer has a viscosity varying from 100 to 500,000 centipoi.se at 25C and more preferably a viscosity varying from 100 to 200,000 centipoise at 25C
where the vinyl content generally varies from 0.0~ to 1.5 percent by weight and more preferably varies from 0.04 to 1.0 percent by weight. The organo groups other than vinyl of such a polymer may be any monovalent hydrocarbon radical such as alkyl radical of 1 to 8 carbon atoms such as methyl ethyl, etc.; alkenyl radicals such as vinyl, allyl, etc.; mononuclear aryl radicals such as phenyl, menthylphenyl, etc.; cyclo alkyl radicals such as cyclohexyl, cyclo heptyl, etc.; and f].uoroalkyl radicals sllch as 3,3,3-trifluoropropyl. Preferably the organo groups are selected from vinyl phenyl and methyl and most preferably being selected from vinyl and methyl, generally such a polymer may have the formula, I 10 t I 10 ~ S o r vi where Vi is vinyl and R10 is a monovalent hydrocarbon radicalO The radical R10 may be any of the radicals noted for the organo groups in the definition of the diorganopolysiloxane vinyl containing polymer. However, preEerably, the vinyl containing vinyl polysilo~ane polymer has the Formula (3) above such that vinyl unit only on the terminal position of the chain and R10 is a monovalent hydrocarbon radical other than an aliphatically unsaturated hydrocarbon radical. Most preferably RlO is selected from the class consisting of me-thyl phenyl and fluoro alkyl radicals and x and y in the formula vary such that the viscosity of the polymer varies rom lO0 to 500,000 centipoise at 25C
and more preferably varies from lO0 to 200,000 centipoise at 25C.
Another basic ingredient in the composition is from O.l to 25 parts by weight of a hydride resin defined above. Preferably the hydride resin contains a hydride content broadly at .05 to 5 percent weight and more preferably .l to l percent by weight. It should be noted that the hydride resin must be present in the SiH Olefin platinum catalyzed composition of the instant case for solubility purposes. Accordingly, per ~5 lO0 parts of the base vinyl containing diorganopolysiloxane polymer, there must be present from .l to 25 parts by weight of a hydride resin as defined above. As pointed our previously, R is selected from monovalent hydrocarbon radicals and R' is selec~ed from hydrogen and monovalent hydrocarbon radicals. The monovalent hydrocarbon radicals can be any radical other than the aliphatically unsaturated hydrocarbon radicals.
Accordingly/ R and R' insofar are monovalent hydrocarbon radicals that can be selected from alkyl radicals of l to 8 carbon atoms, cyclo alkyl radicals, and mononuclear aryl radicals and fluoro alkyl radicals, all up to 8 carbon atoms. Most preferably R is selected from hydroyen, methyl, phenyl, and 3,3,3-fluoropropryl.
It should be noted t:hat the hydride resin might have some vinyl unsatura1:ion but if it does have such vinyl unsaturation it is important the platinum catalyst not be mixed with it, otherwise the resin will cross-link with itself.
The hydride resin is produced by methods well known in ~he art. Such methods generally comprise the 60SI-33~

-- 10 ~
the hydrolysis of the appropriate hydride chlorosilanes, preferably in a water hydrocarbon solvent mixture with the extraction and purification of the resin product.
The other necessary ingredien-t in the composition is from 1 to 500 parts per million of platinum catalyst and more preferably from 1 to 200 parts per million of platinum catalyst. It should be noted that the platinum catalyst may be present as~ solid platinum deposited on charcoal or on gamma ~m~ or it may be solubilized platinum complex. Most preferably it i~
a solubilized platinum comple~
Generally, there must be ~tV~7~ at least 0.1 parts per million of a platinum catalyst in terms of parts of platinum metal. This platinum catalys-t may be in any form. It may be a solid platinum metal deposited on a solid carrier or it may be a solubilized platinum complex. Any type of platinum cataly~t will work in the ins-tant invention. More preferably, the platinum complex is a solubilized platinum complex.
Many types of platinum compounds for this SiH Olefin addition reaction are knowrl and such platinum catalysts may be used for the reaction of the present case.
The preferred platinum catalysts especially when optlcal clarity is re~uired are those platinum compound catalysts which are soluble in the present reaction mixture. The platinum compound can be selected from those having the formula (PtC12Olefin)2 and H(PtC12Olefin) as described in U.S. Patent No. 3,159,601, Ashby. The Olefin sho~n in the previous two formulas can be almost any type of Olefin but is preferably an alkenylene having from 2 to 8 carbon atoms, a cycloalkenylene having from 5 to 7 carbon atoms or styrene. Specific Olefins utilizable in the above formulas are ethylene, propylene, the various isomers of butylene, octylene, cyclopentene/ cyclohexene, cyclGheptene, etc.

A Further platinum containing material usable in the composition of the present invention is the platinum chloride cyclopropane complex (PtCl~C3H~)2 described in U.S. Patent No. 3,159,662, Ashby - issued December 1, 196~.
Still further, the pla-tinum containing material can be a complex formed from chIoroplatinic acid with up to 2 moles per gram of platinum of a member selected from the class consisting of alcohols, ethers, aldehydes and mixtures of the above as described in U.S. Patent No. 3,220,972, Lamoreaux -issued November 30, 1965.
The preferred platinum compound to be used not only as a platinum catalyst but also as a flame retardant a~ditive is that disclosed in Karstedt U.S. Patent No. 3,8~,730 - issued June ~, 1974.
Generally speaking, this type of platinum complex is formed by reacting chloroplatinic acid containing 4 moles of water of hydration with tet.ravinylcyclotetrasiloxane in the presence of sodium bicarbonate in an ethanol solution.
It should be noted that the preparation of such hydride resi.ns and also the solubilized platinum catalyst are well known to a worker skilled in the art.
Preparation of a base vinyl containin~ polymer is also well k:nown -to a worker skilled in the art and generally comprises taking cyclotetrasiloxanes o~ the appropriate organo substitution or of the desired organo substitution, and equilibrating them at elevated temperatures in the presence o~ an alkali metal hydroxide with the appropriate amount of chain stoppers. The chain stoppers are preferably low molecular weight vinyl terminated diorganopolysiloxane polymers; for instance, divinyltetramethyldisiloxane.
From the resulting equilibration, there results the ~ ~ ~ V~ 60SI-338 desired polymer and when the equilibration is completethat is when about 8~ percent of cyclotetrasiloxane has been converted to linear polymer, the reaction temperature is lowered, the alkali metal hydroxide catalyst is neutralized, preferably with acidic a~ent such as a chlorosilane or a silyl phosphate or a phospheric acid, and the excess cyclics that are unreacted are vented off to give the desired polymer.
When it is desired to produce a low molecular weight diorganopolysiloxane polymer in the viscosity range of 50 to 10,000 centipoise at 25C, then there may be utilized an acidic catalyst in such equilibration reaction such as toluene sulfonic acid or acid treated clay such as Filtrol, manufactured and sold by the Filtrol Corporation of Los Angeles, California.
~nother necessary ingredient in the composition is generally f-rom .5 to 8 parts by weic~ht and more preferably from 1 to 5 parts by weight of the acryloxy silane. In formula 1 above, R , R and R
are monovalent hydrocarbon radicals. Such monovalent hydrocarbon radicals can be any of the monovalent hydrocarbon radicals defined previously for the vinyl containin~ base polymer. Accordin~ly, such monovalent hydrocarbon radicals can be alkyl radicals of 1 to 8 carbon atoms, mononuclear aryl radicals such as phenyl, alkenyl radicals such as vinyl, cyclo alkyl radicals such as cyclo hexyl, fluoro alkyl radicals such as

3,3,3-trifluoropropyl. Most preferably R , R , and R are selected from alkyl radicals of 1 to 8 carbon atoms such as methyl, and R3 is a divalent hydrocarbon radical and is preferably selected from alkylene and arylene radicals of up to 8 carbon atoms. Preferably R3 has at least 3 carbon atoms. It has been found that the compound is not hydrolytically stable if it has less than 3 carbon atoms. Most preferably, R3 ~ 3~ 60SI-338 ~ 13 -is propyl since the propyl group is hydrolyti.cally stable and is most readily available for producing the compounds of Formula 1, A can be as a is a whole number that varies from 0 to 2 and is most preferably 0 Preferably, the compound of Formula 1 is formed by the following reaction, R2 o C~I2 ~- C -- C O R13 +
R
la H - li (OR )3-a where R13 is an aliphatically unsaturated monovalent hydrocarbon radical of at least 3 carbon atoms, generally of 3 to 8 carbons where R , R and R are as previously defined. The above reaction is carried out in the presence of a platinum catalyst and is well known in the silicone chemical art. The hydrogen group adds on ~o the olefinically ~msaturated group R13 in the presence of the platinum catalyst to form -the compound of Formula 1, the acryloxy intermediate for forming the compound of Formula 1 is readily available ln the industry and is sold by chemical companies such as Union Carbide Corporation and Dynamit Nobel Chemical Co.
In place of the acryloxy silane self-bonding additive that may be utilized at the same concentrations and the acryloxy polysiloxane self-bonding additiVe of Formula 2. Such acryloxy polysiloxane compounds are formed from the following reaction, R O

CH2 -- C C O ~ +

- H ~bl 4 - a - b ~ 60SI-338 Again, this is a well-known reaction in silicone chemistry which is cured out presence of platinum catalyst and can be any of the platinum catalysts identified previously for the compositions of the present invention. In the above formulas o~
the hydride polysiloxane a varies from 0.05 to 2.0~
b varies from 1.0 ~o 2.5 and the sum of a plus b varies from ln 005 to 3Ø
In the Formula 1, and as well as in the hydride formula polysiloxane above, Rll is a monovalent hydrocarbon radical that can be any of the monovalent hydrocarbon radicals identified previously for the base vinyl containing polymer. Accordin~ly, R can be the alkyl radical of l to 8 carbon atoms, a mononuclear aryl radical, an alkenyl radical, a cycloalkyl radical or a fluoroalkyl radical. Most preferably Rll is selected from methyl vinyl and phenyl and 3,3,3-trilfuoropropyl. The acryloxy olefinic unsaturated compounds which are utilized in this reaction to produce the acryloxy polysiloxanes and the acryloxy silanes can be ob-tained ~rom the above manufacturers of chemical compounds as identified previously.
In preparing the composition, the acryloxy s:ilane or siloxane is first mixed with a hydride resin and has to be mixed with resin first, irrespective of whether additional ingredients are then added as will be described below. The platinum catalyst is mixed with a vinyl containing polysiloxane base polymer.
When it is desired to cure the composition, the two components are mixed and applied to whatever substrate it is desired to adhere thereto and the composition will at room temperature cure to a silicone elastomer or cure at elevated temperatures to silicone elastomers, that is above 80C and 150C. The cure at above 100 C
is extremely rapid, in a matter of minutes or even seconds.

~lowever, to improve the self~bonding properties of the compositions, there may be added to the composition at least 400 parts per million of a self-bonding promoter having at least one hydroperoxy radical. Accordingly, generally there may be utilized ~00 to 10,000 pzrts per million of a hydroperoxy compound as a self-bonding promoter, or preferably fxom 400 to 2,000 parts per million of a self-bonding promoter, which compound contains a hydroperoxy radical. Most preferably, the self-bonding promoter is methyl ethyl ketone hydroperoxide. Other hydroperoxide self-bondiny promoters that may be utilized are 1,1,3,3-tetramethylbutyl hydroperoxide, 2,5-dimethyl-2,5-dihydroperoxy hexane, cumene hydroperoxide, 1,1,3,3-tetramethylbutylhydroperoxide, 2,5 dimethyl-2,5, dihydroperoxy hexane, decalin hydroperoxide, l,1,2,2-tetramethylpropyl, p-methane hydroperoxide and pinane hydroperoxide. These compounds are manufactured and sold by Pennwalt Corp., Hercules, Inc., and Lucidol Chemical Company.
It should be noted that these compounds are taken out o U.S. Patent No. 4,061,609 - W.S. Bobear, issued December 6, 1977. It should be noted these hydroperoxy compounds are disclosed in the foregoiny ~5 patent as inhibitors and as very effective inhibitors in SiH Olefin platinum catalyzed compositions. They are not disclosed in the patent as self-bonding promoters.
It is only in the present application that they are disclosed as self-bonding promoters.
It also should be noted that the most effective acryloxy silane self-bonding additive that is desirably utilized in the present invention, is ~ - methyl a~ryloxy propyl trimethoxy silane. To urther increase the self-bonding properties of the composition there may also be incorporated per 100 parts of the ~ ~ ~ 60SI-338 base polymer from 2 to 25 parts by weight of a fumed silica which is treated with silazanes. This is another self-bonding promoter which by the use of siloxane treated fumed silica the self-bonding properties of the composition are improved over compositions not having such silazane treated ~umed silica. The fumed silica may also be treated with cyclotetxasiloxanes in addition to the silazanes.
However, this is not necessary. An example of such treatment of such fillers is for instance to be found in the Beers U.S~ Patent Mo. 3,837,878 - issued September 24, 1974. Preferably, there is utilized only from 2 to 15 parts by weight oE fumed silica treated with silazanes. However, it is not desired to utilize more than 25 parts of fumed silica in any case hecause the viscosity of the composition becomes too high for the composition to be used in silk screen printing applications. ~owever, the composition with a high viscosity may be utilized in other applications such as encapsulation and potting of electrical components. The treatment of fumed silica with cyclotetra siloxane and silazanes is well known in the art.
In addition to such treatment and utilization of fumed silica there may be utilized an extending filler. Generally, there may be utilized anywhere from 5 to 100 parts of an extending filler and more preferably from 5 to 50 parts of an extendiny filler based on 100 parts by weight of the base vinyl containing polymer where the extending filler is selected from a class consisting of titaninum oxide lithopone, zinc oxide, zirconium silicate, silica aerogel, iron oxide, diatomaceous earth, calcium carbonate, glass fibers, magnesium oxide, chromic oxide, zirconium oxide, magnesium oxide, alpha quartz, calcined clay, carbon graphite, cork, cotton and synthetic fibers. These fillers are disclosed in William Bobear, U.S. Patent No. 4,061,609. A patent on the use oE the silazanes to treat fumed silica i5 U.S. Patent No. 3,635,743 - issued January 18, 1972.
Accordingly, with these additional ingredients of the hydroperoxy compound along with a silazane treated fumed silica there is disclosed a very desirable and advantageous self-bonding SiH Olefin platinum catalyzed composition. Accordingly, with the hydroperoxy self-bonding promoter and the silazane treated fumed silica which can be added with advantayes to the acryloxy silane or siloxane composition, there is obtained a very advantageous self-bonding addition cure system. It may be utilized in silk screening applications as it has the desired adhesion to various types of substrates. The substrates to which good adhesion is obtained from by the above composition with the foregoing self-bonding promoters are copper, aluminum, polyvinylchloride, glass, polyethylene terephthalate, epoxy fiberglass, phenolic-linen, Lexan, trade name for polycarbonates~ styrene, n~lon, polyphenylene oxides. It should be noted that most preferably the ex-tending filler is alpha quartz, since alpha quartz increases the tensile strength of the composition without increasing to too great an extent the viscosity of the uncured compositions.
It should be noted that any of the extending fillers may be utilized with advantage to increase the tensile strength of the composition without necessarily increasing the viscosity of the uncured composi-tion by a great extent. In the present case, there may also be incorporated additional hydride for curing purposes, to increase the rate of cure when it is desired, that is by the heating of the composition by - :L8 -elevated t.emperatures. There may be present from 1 to 50 parts by weight of a resin hydride polysiloxane of the formula,

(4) H - - t sio ~ slo si H

where R6 is selected from the class consisting of a monovalent hydrocarbon radical and a mixture of hydrogen and a monovalent hydrocarbon radical s is 0 or a positive number and t is a 0 or a positive number such that the polymer was a viscosity varying from 10 to 1,000 centipoise at 25C or more preferably has a viscosity varyiny ~rom 10 to 100 centipoise at 25 C. The R6 :L5 radical is preferably selected from alkyl radicals of 1 to 8 carbon atoms, cycloalkyl radicals, mononuclear aryl radicals, fluoroalkyl radicals, and other monovalent hydrocarbon radicals. It should be noted that R6 can be alkenyl radicals such as vinyl as long ~0 as the platinum catal.yst is not packaged with it in the formation oE the 2 component composition system.
The xadical ~6 is preferably selected from emthyl, phenyl, and 3,3,3-tri-~luoropropyl radi.cals. Normally the hydride polysiloxane generally as a hydride content varying anywhere from 0.15 to 2.0 percent by weight and more preferably has a hydride content varying from 0.25 to 1.7 percent by weight. Preferably there is utilized as an additional hydride polysiloxane 1 to 20 parts by weight of the hydride polysiloxane based on 100 parts of the base vinyl containing polymer of Formula 3.
It should be noted that there must be present in the composition of the instant case in order for it to be soluble, the hydride resin. Such ,~, ~ a hydride resin should be present in the composition ~ OSI-338 and must be first mixed with the acryloxy silane -to be soluble. ~s an additional hydride additive or in place oE the hydride resin in order to increase the cure rate of the system, there may be present a linear hydride polysiloxane of the formula shown above. The hydride of polysiloxane of the formula shown above is a well known chemical in the art and may be obtained by the hydrolysis of the appropriate chlorosilanes to produce the desired hydride polysiloxane.
Preferably, there should be a hydride resin in the composition and such hydride resin must be first mixed with the acryloxy silane and acryloxy polysiloxane initially in order for the composition to have the desired solubility properties of the instant case.
After the hydride resin has been mixed with the acryloxy silane and polysiloxane, there may be added to it the linear hydride polysiloxane polymer disclosed above.
There may also be added to the composition reinforcing resins. Such resins take the place of silica fillers and increase the ~ensile strength of the cured composition as well as the tear strength of the cured composition wi.thout unduly increasing the uncured viscosity o~ the composition so that there may be incorporated into the composition per 100 parts of the base polymer from l to 70 parts by weight of a resin composed of R3 SiOo 5 Si 2 where R7 is a radical selected from the class consisting of vinyl radicals, alkyl radicals and aryl radicals and fluoroalkyl radicals of l to 8 carbon atoms with a ratio of monofunctional units to tetrafunctional units and is from 0.5 to l.l and where from about 2.5 to mole percent of the silicone atoms contain silica bonded vinyl groups.
In place of such a resin there may be incorpora-ted in the composition of a resin composed of 8~

monofunctional units, -tetrafunctional units, difunctional units. Accordingly, per 100 parts of a base vinyl containing polymer, there may be incorporated in the composition from 1 to 70 parts by weight of a resin comprising R3 SiOo 5, R SiO units and SiO2 units where R is a radical selected from the class consisting of vinyl radicals, alkyl radicals, aryl radicals and fluoro alkyl radicals where the ratio of monofunc-tional units to the tetrafunctional units is from .5 to 1 and 1:1 and the difunctional units are present in an amount equal to about 1 to 10 mole percent based on the total number of moles of siloxane units in the copolymer and wherein from about 2.5 to 10 mole percent of the sili.cone atoms containing silicone bonded vinyl groups. Such resins are known for such Olefin platinum catalyst compositions as disclosed in Modic U.S. Patent No. ~ - issued ~ , 1969.
The composition may also contain other additives and ingredients such as heat aging additives, additional flame retardant additives and swell resistant additives, if the composition is not fluorosilicone, etc. It should be noted that the hydroperoxy compound in the composition will act as an inhibitor. However, if used in the present invention it is being utilized first of all as a self-bonding addi-tive and then as an inhibitor. Accordingly, per 100 parts of the total composition there may be utilized from 100 to 10,000 parts per million of an additional inhibitor compound in tne composition such as trialkenylisocyanurate. Suitable inhibitor compounds may be uti~ized as long as they do not conflict with the self-bonding properties or self-bonding activity in the system of the ac~yloxy silane and siloxane.

It has been found -that trialkyenylisocyanurate does not interfere with the self-bondinc~ properties of acryloxy silane and acryloxy polysiloxane. The inhibited composition has a desirable work life at room temperature but when heated at elevated temperatures would cure in the matter of minutes or seconds to a silicone elastomer. With an inhibitor such as trialkenylisocyanurate in the composition, the composition may have hours or even days of shelf life without curing at room temperature. The hydroperoxy compound may be utilized also as an inhibitor but should be preferably utilized in the concentrations disclosed used above it if lt is to act as a self-bonding promoter in the instant composition and secondly as an inhibitor. If it is utilized at more than the concentrations indicated above, then the self-bonding promoter properties of the hydroperoxide are not changed but the composition is considerably more inhibited.
To prepare the cured composition the vinyl polymer optionally, the vinyl resin, the filler are all mixed together along with the platinum catalyst to form one component. Then the hydride resin is mixed with the acryloxy silane or acryloxy polysiloxane, and then there is added to them preferably a linear hydride polysiloxane. A hydroperoxy self-bonding promoter additive and optionally the filler is added to the vinyl polymer. Accordingly, when it is desired to cure the composition the two components are mixed together to form a uniform mixture preferably in a 10 to 1 mixing weight ratio, then the composition is applied to whatever form it is desired. In one embodiment the composition can be applied to a silk screen and then pressed through the silk screen by the wiper bars into the substrate below which may be of ~ 60SI-338 ceramic, plastic or glass and the composition is then heated at e]eva-ted temperatures to cure the composition to the desired shape so as to Eorm, ~or instance, a gasket on a metal, plastic or ceramic substrate by -the silk screen printing method. It should be noted that the silk screen is varnished in all the areas except the areas it is desired that the composition pass through it to form the desired shape for the printed matter that is going to be placed on the substrate.
All parts in the examples below are by weight. The examples below are given for the purpose of illustrating the present invention and they are not given for the purpose of setting limits and boundaries of the present invention. In the examples below, there was utilized a composition A. Such composition may comprise oE 100 parts of vinyl terminated dimethylpolysiloxane polymer having 0.14 percent vinyl and a viscosity of 3~00 centipoise at 25C. Wi~h this polymer there is mixed 33 parts of a resin composed of trimethylsiloxane units of SiO2 and methyl vinyl SiO
units with a ratio o~ mono unit to the tetra and the difunctional units in an amount sufEicient to provide 0.8 trimethylsiloxane units per SiO2 -unit and with the methylvinylsiloxane units heing present in an amount such that 7.0 mole percent of the methylvinylsiloxane atoms are present as methylvinylsiloxane units and the remaining silicone atoms are present as a por-tion of a trimethyl siloxane unit or an SiO2 unit. In the example~ there was utilized a linear hydride composed of hydride dimethylsiloxy terminal units and methyl hydrogen siloxane units in the internal portion of the polymer chain where the viscosity of the polymer was lO centipoise at 25C and the hydride concentration of the polymer was 1.7 percent by weight Example 1 Composition A above was taken and there was mixed into 100 parts of Composition A, 10 parts of Composition B made by mixing 28 parts o~ gamma methacryloxypropyltrimethoxysilane with 64 parts of a resin composed o hydrogen dlmethylsiloxy units and SiO2 units, containing an average of two of the dimethyl hydrogen units per SiO2 unit and 7 parts of the linear hydride disclosed above. This was the weight ratio of one component to the other in component B. From the cured composition ASTM sheets were made and cured at 100C for 1 hour in a heated press. The adhesion was measured via a lap joint adhesion using Alclad aluminum panels and 1 square inch, 25 mil thick bond. The samples were pulled at .5 inches per minute.
The test on the physical properties yield the following result. Durometer, Shore: 41; Tensile psi: 575;
Elongation gO 110; Tear lb./in.: 15; lap shear psi: 500;
% Cohesion: 100%.
xample 2 To 100 parts of Composition A there was added 10 parts of component B comprising 50 parts of the resin hydride oE Example 1 and 50 parts of a vinyl terminated dimethylpolysiloxane polymer having 0.14 percent vinyl and a viscosity of 3800 centipoise at 25C. The resulting cured sheets had the following properties: Shore A durometer: 35;
tensile psi: 750; Elongation %: 120; Tear lbs./in.: 10;
~ap Shear psi: less than 1; % Cohesion: 0.
Example 3 The composition of Example 1 was used as a potting compound for 1" x 4" strips of a substrate shown in Table I. The silicone was cured at 80C for 1 hour. The silicone was examined for adhesion to the substrate by scrapping and pulling the silicone off with a razor blade. Composition A was cured with - 2~ -Composition B of Example 2 at a 10 to 1 ratio and used to po~ the substrates for the sake of comparison.
Characteristic of dimeth~lvinyl chain-stopped organopolysiloxanes, the cured silicone elastomer delaminated and readily released free of the substrates.
Example 4 Then to Composition A above there was added 610 parts per million of methylethylketone hydroperoxide. With the hydroperoxide the shelf life exceeded 6 months for the catalyzed composition. Pot li~e exceedin~ 6 months are obtained when the hydro hydroperoxide is added to the mi~ture of Example 1.
Further, the number of plastics to which the composition adheres to ls increased as shown in Table 1 below.
With the addition of the hydroperoxide the catalyst composition must be subjected to a post bake of 125C
for 10 minutes to complete the cureO In all other respec~s the composition was processed the same as in the Example 1. The results are set forth in Table 1 below.
T.~BLE I
c~l~L~ d~e~i~
ubstrate Example 3Example Polyvinyl chloride Good Good Copper Good Good Glass Good Good Polyethyl.ene terephthalate Good Good Epoxy-fiberglass Good Good Phenolic - linen Good Good Lexan None Good Styrene None Good Nylon None Good Noryl None Good Polyvinyl acetate None None Acrylic None None 8~

Examp e 5 Prepared a Composition C which had the same composition as Composition A but the proportion of a vinyl polymer to a vinyl resin was 60~ by weight of polymer per ~0% by weight o~ resin while the composition is 75% by weiyht of polymer to 25% by weight of vinyl resin in Composition A~ The composition C was cured with the component B o-f Example 1 at room temperature.
The silicone gelled within 2~ hours and cuxed to a transparent compound with a Shbre llardness of 35. In comparison, when the gamma methyl acryloxy propyl trimethoxy sllane was added directly to composition A
a precipitate immediately developed. The precipitate remained even after the addi-tion of the linear silicone hydride. This mixture, cured either at room temperature or up to 150C, resulted in an opa~ue compound exhibiting intermittent cohesive bonding with less than 25% to aluminum panels.
The acryloxy silane o~ Example 1 was added to dimethylvinyl chain-stopped organopolysiloxane having a viscosity of 80,000 centipoise at 25C and a dimethyl-vinyl terminated polysiloxane polymer having a viscosity of 3800 centipoise at 25C. ~ precipitate formed, and after 24 hours yellow liquid was collected which was identified as the acryloxysilane of Example 1.
These results were duplicated using the linear hydride polysiloxane as well. The acryloxysilane was soluble and stable for more than a year only when first rnixed with the methyl hydride resin. The resin hydride may, be made by reacting ethylsilicate with dimethylhydrogen chlorosilane in water. When the acryloxy of Example 1 is first mixed wi~h the resin hydride, shel-f stable solutions using other linear hydrogen polysiloxanes and clear organo polysiloxane compounds can be made.

~, ~
,~,J ' In these examples, solutions of curing ayents containing the acryloxysilane of Example 1 and silicon hydrides were made and cured and used to cure C'omposition ~, a resin reinforced vinyl chainstopped polymer. The solutions were made by first mixing together the acryloxysilanes of Example 1 and the hydride resin and then adding the remaining component. Ten parts of curing agent were added to 100 parts or polymer. Adhesion was tested to aluminum by curing 30 grams of the mixed compound on an aluminum weighing dish. The samples were cured for 1 hour. When methylethylketone hydroperoxide was added to Composition A, a cure temperature of 125C was used. The adhesion was determined by the cuttiny of 1/2" strips of the cured compound out of the aluminum dishes and peeling the aluminum strip off using an Instron, Model TM. The strip was pulled at 90C at a rate of 12" per minute. The values are reported in lbs./in. and the strips were examined for cohesive failure as set forth in Table II below.
TABLE II
Example 6 7 8 9 10 11 12 13 1~ 15 B Component ~ydride Resin 64.2 74.8 47.0 83.6 79.1 74.0 83.7 81.9 61.7 35 of Example Acry]oxy 28.3 16.4 44.2 16.4 16.5 16.4 16.3 18.0 13.6 7 Silane of Example 1 Linear 7.5 8.8 8.8 4.4 24.7 56 Hydride 1 Linear 8.6 Hydride 2 Methyl ethyl 606 606 606 ketone hydroperoxide (added to "A"
Parts) ppm _ ~7 _ TABLE II (Cont'd) Example 6 - 7 8 9 10 11 12 13 14 15 . . _ ~ _ _ _ _ Properties Cure Temp.100 80 100 100 100 100 125125 125 10 C for 1 hour % Cohesive100 100 100 100 100 100 100100 100 10 Bond Strength 3 2.5 3.2 2.8 2.72~9 2.6 2.6 2.6 2.0 lbs./in.
Shore A 32 32 30 33 32 31 33 31 29 Room Temp.24 5 24 24 24 24 72~720 720 5 Gel Time, h-urs % MEMOS in28.3 16.4 44.2 16.4 16.5 16.4 16.318 13.6 7.8 Part B
~ MEMOS in2.6 1.5 4.0 1.5 1.5 1.5 1.5 1.6 1.2 0.7 cured RTV
1. Linear hydride of Example 1.
2. Linear hydride comprising a polysiloxane having hydrogen terminal units and methyl hydrogen on chain with a viscosity of 55 centipoise at 25C and weight percent hydrogen o 1.0%.
Example 16 The cornposition of Example 6 was mixed and weighed into an aluminum dish. The compound was cured at 100C for one hour and percent solids as weight was determined. The loss was found to be .4 percent by weight. The cured sample was heated further at 150C
for 720 hours without experiencing any further weight loss. A sample of Composition A and Composition B of Example 2 was tested under the same condition and had a weight loss of .2 percent by weight.
Example 17 Solutions of the hydride resin containing 10, 20 and 50 percent weight of methyl methacrylate were made and were used to cure Composition A using a ratio of 100 parts of Composition A to one part of the curiny agent. The cure was carried out at either 80C or 100C. The samp:Les did not evidence any adhesion to aluminum and developed a cloudy 2 phase system.
No adhesion was obtained with addition to the system of methyl ethyl ke~one hydroperoxide.
Substitution with triallylisocyranuate resulted in no cure or adhesion.

Claims (12)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A self-bonding addition curing silicone composition consisting essentially of:
(A) 100 parts by weight of a base vinyl contain-ing diorganopolysiloxane of a viscosity varying from 100 to 500,000 centipoise at 25°C where the vinyl content varies from 0.04 to 1.5 percent by weight and the organo groups are monovalent hydrocarbon radicals;
(B) from 0.1 to 500 ppm of platinum catalyst;
(C) from 0.1 to 25 parts by weight of a hydride resin selected from the class consisting of resins having HR2SiO0.5 units and SiO2 units where the ratio of H+R units to Si varies from 1.0 to 2.7 and resins having HR2SiO0.5 units, SiO2 units and R2SiO units where the ratio of H+R+R
to Si varies from 1.2 to 2.7 where R is a monovalent hydrocarbon radical and R1 is selected from hydrogen and monovalent hydrocarbon radicals; and (D) from 0.5 to 8 parts by weight of a self-bonding siloxane additive of the formula where R2 and R11 are monovalent hydrocarbon radicals, R3 is a divalent hydrocarbon radical, a varies from 0.005 to 2.0, b varies from 1.0 to 2.5, and the sum of a+b varies from 10005 to 3Ø

2. The composition of claim 1, further comprising from 2 to 25 parts by weight of a fumed silica treated with silazanes.

3. The composition of claim 2, wherein there is further present from 5 to 100 parts of an extending filler.

4. The composition of claim 3, wherein said extending filler is alpha quartz.

5. The composition of claim 1, wherein there is further present from 1 to 50 parts of hydride polysiloxane of the formula where R6 is selected from the class consisting of a monovalent hydrocarbon radical and a mixture of hydrogen and a monovalent hydrocarbon radical, s is 0 or a positive number, and t is 0 or a positive number such that the polymer has a viscosity varying from 10 to 1,000 centipoise at 25°C.

6. The composition of claim 1, wherein there is further present from 1 to 70 parts by weight of a resin comprising (R7)3 SiO0.5 units and SiO2 units where R7 is a radical selected from -the class consisting of vinyl radicals, alkyl radicals, aryl radicals, and fluoroalkyl radicals, where the ratio of monofunctional units to tetrafunctional units is from 0.5:1 to 1:1 and where from about 2.5 to 10 mole percent of the silicone atoms contain silicone bonded vinyl groups.

7. The composition of claim 1, wherein there is further present from 1 to 70 parts by weight of a resin comprising (R7)3 SiO0.5 units, R7SiO units and SiO2 units, where R7 is a radical selected from the class consisting of vinyl radicals, alkyl radicals, aryl radicals, and fluoro-alkyl radicals, where the ratio of monofunctional units to tetrafunctional units is from about 0.5:1 to 1:1 and the difunctional units are present in an amount to equal from about 1 to 10 mole percent based on the total number of moles of siloxane units in the copolymer, and where from about 2.5 to 10 mole percent of the silicone atoms contain silicone bonded vinyl groups.

8. The composition of claim 1, wherein the base vinyl containing diorganopolysiloxane polymer has the formula, where Vi is vinyl, R10 is selected from the class consist-ing of methyl, phenyl and fluoroalkyl, and x and y vary such that the viscosity of the polymer varies from 100 to 500,000 centipoise at 25°C.

9. The composition of claim 1, wherein the platinum catalyst is platinum complexed with a compound selected from the class consisting of alkenyl and aryl alcohols.

10. The composition of claim 1, wherein the platinum catalyst is platinum complexed with a vinyl containing dimethylpolysiloxane.

11. The composition of claim 1, further comprising from 100 to 10,000 parts per million of an inhibitor compound.

12. The composition of claim 11, wherein the inhibitor compound is triallylisocyanurate.