GB2065661A - Silicone foam compositions with burn resistant properties - Google Patents

Abstract

A burn resistant silicone foam composition comprises a vinyl- containing polysiloxane, optionally a filler, a hydrogen-containing polysiloxane, a platinum catalyst and a silanol containing compound. It can be foamed at room temperature to provide a burn resistant material for electrical systems and especially for electrical systems in nuclear plants.

Description

SPECIFICATION Silicone foam compositions with burn resistant properties Background of the invention The present invention relates to the silicone compositions and more particularly the present invention relates to silicone compositions which can be foamed at room temperatures or at elevated temperatures to produce a burn-resistant insulative foam. Silicone compositions are well known. Such compositions generally comprise a silicone polymer and various additives which are cured to a silicone elastomer at room temperature or at elevated temperatures. In the case of SiH Olefin platinum catalyzed compositions, such compositions generally comprise a vinyl containing polysiloxane, a hydrogen-containing polysiloxane and a platinum catalyst.Such a silicone composition can be foamed at room temperature to provide a burn-resistant material for electrical systems and especially for electrical systems in nuclear plants.

The resulting composition after the ingredients are allowed to come in contact with each other cures to a silicone elastomer at room temperature. By incorporating an inhibitor in the composition, the composition can be prevented from curing at room temperature for varying periods of time, but will cure rapidly at elevated temperature. Such compositions as indicated above will cure to a silicone elastomer. There are other compositions that will cure to an elastomer; for instance, a composition which is cured with an organic peroxide which is normally referred to as a heat-curable silicone rubber composition; or a composition that cures by condensation by giving off by-products.However, the Si-H olefin platinum catalyzed compositions are preferred over these compositions for certain applications for a number of reasons; first of all, the composition does not require the presence of a catalyst which may attack other systems; secondly, this type of composition is advantageous over the acetoxy-curing room temperature vulcanizable silicone rubber composition since it does not give off corrosive by-products upon curing. In fact, it does not give off any by-products at all. Accordingly, such SiH olefin platinum catalyzed compositions are highly desirable for the above reasons. An example of a silicone SiH olefin platinum catalyzed composition is for instance one to be found in the patent of Frank J. Modic, U.S.P. 3,436,366 which is incorporated by reference.The patent discloses a high-strength composition comprising a vinyl-containing polysiloxane polymer, a resin composed of monofunctional units and tetrafunctional units or optionally a resin-composed monofunctional units, difunctional units and tetrafunctional units. The presence of the resin increases the strength properties of the composition. It was found that such a composition could be foamed into a silicone foam as disclosed in the patent of Modic, U.S. Patent 3,425,967 which is incorporated by reference.This patent discloses as a foamable composition, a vinyl-containing polysiloxane, a silicone resin, which may comprise of monofunctional units, and tetrafunctional units; an organic fiberous material filler which is selected from the class consisting of asbestos and fiberous potasium titanate optionally a finely divided inorganic filler, a catalyst, an organic hydrogen polysiloxane and a blowing agent. The purpose of this U.S. Patent 3,425,967 is to disclose the development of a high strength silicone foam which can be utilized to form fabricated articles which are flame retardant, but which are tough, that is they can be used and abrated without coming apart easily.

The silicone foam disclosed in Modic U.S. Patent 3,425,967 can be utilized as a paneling material, as a flame-retardant bearier which is going to take abrasion resistance and is highly suitable for these purposes.

It should be noted that while asbestos is not desirable as an ingredient in such compositions, otherfiberous materials can be utilized as fiberous fillers to help enhance the tensile strength and the toughness of the silicone foam that is formed from the Modic '967 disclosure. It should be noted that the composition of the '967 patent needed an external blowing agent which may be any of these blowing agents disclosed in Column 5, beginning with line 36 of the patent or any other type of suitable external blowing agent.

There are two disadvantages with having such external blowing agents as disclosed in the '967 patent.

First of all, there is the expense of having the chemical blow agent as an additional ingredient in a composition, both in the cost of the material and also the cost of incorporating it in the composition.

Secondly, the disadvantage of such a blowing agent, is that in order to trigger the system, the composition has to be heated at elevated temperatures. This makes it quite difficult, if not impossible to form a silicone foam in situ in a nuclear plant or another building or structures. Accordingly, it would be highly desirable if such silicone foam compositions would foam at room temperature so that the ingredients could be metered into the conduit in a nuclear plant or some other time of structure, resulting in a silicone foam being formed in in situ in the conduit as necessary. Recent attempt to produce an acceptable room temperature forming silicone foam for the insulation of electrical system from fire is to be found in the disclosure of Smith U.S.

Patent 3,923,705. This patent discloses the reaction of a silanol containing polysiloxane with a SiH material in the presence ot platinum catalyst to form a silicone foam at room temperature as is desired or at elevated temperatures as is desired. While having some advantages, one disadvantage with this system was that it would not create a suitable foam with all types of platinum catalysts. The composition needed the fastest type of Karsteadt platinum complex as disclosed in U.S.P. 3,775,452 as will be disclosed below for the production of a suitable silicone foam. Furthermore, the foam that was formed from different catalysts would not be the same. Accordingly, a reliable foam would not be formed from the composition of the Smith patent unless the Karsteadt platinum complex or a similar catalyst was utilized to produce the foam.The other disadvantage with a flame retardant foam of the Smith patent was that it did not have sufficient tensile strength to be uitlized to fabricate articles where abrasion resistant and toughness was important, such as ceiling material or paneling material. Finally the silicone foam of Smith '705 patent suffered from the fact that the basic system was substantially a silanol SiH platinum catalyzed system where up to 85% of the composition could be vinyl. Such a system is not as reliable as the vinyl SiH Olefin platinum catalyzed system in terms of curing rates and reproducable physical properties and accordingly, requires more demanding quality control.

Accordingly, it would be highly desirable if there could be incorporated more than 85% by weight of a vinyl polysiloxane so as to increase the strength of the composition and also to make the silicone foam composition as formed from batch to batch more reliable and more reproducable in physical properties.

To overcome this difficulty, there was filed the docket of Frank J. Modic, Docket 60 Sl-78 entitled "A Silicone Foam Composition Which Has Burn Resistant Properties" which was filed on March 13, 1978, S/N 886,186.

This application discloses the formation of a silicone foam comprising of vinyl-containing polysiloxane, a hydrogen-containing polysiloxane, a platinum catalyst, with other ingredients and a small amount of water, where water acts as the blowing agent. While overcoming the difficulties with prior art composition, the only difficulty with this composition was that if the composition was allowed to stand for some period of time, the water would separate out from the other ingredients and it would be necessary to physically mix the water into the other ingredients before the two parts of the composition were mixed and the composition was allowed to be foamed to a silicone foam. Accordingly, it was highly desirable to have a silicone foam composition which could be foamed at room temperature and which could overcome the difficulties of this prior art composition.

Summary of the invention In accordance with the above there is provided by the present invention a silicone composition capable of being foamed and having burn resistant properties comprising (a) 100 parts by weight of a base vinyl-containing polymer of the formula.

where R and R' are selected from the class consiting of alkyl radicals of 1 to 8 carbon atoms, aryl radicals, vinyl radicals and of 3 to 8 carbon atoms, such that the polymer contains from 0.0002 to 3% by weight vinyl and x varies such that the viscosity of the polymer rises from 100 to 1,000,000 centipoise at 25"C; (b) from 1 to 10 parts by weight of silanol-containing organo silicone compound having a viscosity varying from 1 to 100 centipoise at 25CC where the organic groups are selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, vinyl radicals, aryl radicals, and fluoro-alkyl radicals of 3 to 8 carbon atoms such that polymer has a silanol content varying from 2 to 10% by weight and more preferably from 5 to 10% by weight (2) from 0 to 200 parts by weight of a filler; (d) from 1 to 50 parts by weight of a hydrogen siloxane of the formula,

where R2 is selected from the class consisting of hydrogen alkyl radicals of 1 to 8 carbon atom radicals and fluoro-alkyl radicals of 3 to 8 carbon atoms and R3 is selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, aryl radicals and fluoro-alkyl radicals of 3 to 8 carbon atoms where the hydrogen polymer has a hydrogen content varying from 0.3 to 1.6% by weight and z varies such that the polymer has the viscosity varying from 5 to 100 centipoise at 25"C when there is also at least 1 mole of SiH per mole of silanol; and (e) from 1 to 250 parts per million of a solubilized platinum catalyst.

The only restriction of the platinum catalyst is that it be a solubilized complex that is easily dispersed in the ingredients and not solid platinum on charcoal. Although such solid type of platinum catalyst will function to some extent, a suitable foam cannot be formed without one of the solubilized platinum complexes. Any type of solubilized platinum complex can be utilized to form a suitable and reproducible foam.

There may be incorporated from 10 to 100 parts of the base vinyl containing polymer of a resin composed of monofunctional units and tetrafunctional units or of a resin composed optionally of monofunctional units and tetrafunctional and difunctional silicon units. In addition, there may be present in the composition, a fiberous filler as well as one of the normal reinforcing or extending fillers.

Description of the preferred embodiment There is preferably in the present composition 100 parts by weight of a vinyl containing polymer of Formula 1. The basic vinyl-containing polymer has Formula (1) shown previously. In such formula, Rand R' may be selected from the hydrocarbon and halogenated hydrocarbon radical with a proviso that there is present from 0.0002 to 3% by weight of vinyl substitution in the polymer, which vinyl substitution must be present such that the viscosity of the polymer varies from 100 to 1,000,000 centipoise at 25"C.

Accordingly, such hydrocarbon groups and halogenated hydrocarbon groups may be selected from alkyl radicals, methyl, ethyl, propyl, etc.; cycloalkyl radicals such as, cyclohexyl, cycloheptyl, cyclooctyl, etc.; mono-nuclear aryl radicals such as, phenyl, methylphenyl, ethylphenyl, etc.; alkenyl radicals such as, vinyl, alkyl, etc. and more preferably, vinyl and other well known substituent groups for diorganopolysiloxane polymers.Preferably, the R and R' radicals are selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, aryl radicals such as, phenyl, vinyl radicals and halogenated hydrocarbon radicals such as, fluoroalkyl radicals of 3 to 8 carbon atoms, such as, for instance, 3,3,3-trifluoropropyl. Most preferably, the R and R' radicals are selected from methyl radicals, phenyl radicals, vinyl radicals and 3,3,3-trifluoropropyl radicals where the polymer has the foregoing vinyl substitution.

The preferred viscosity range of the polymer is, of course, a little more limited in that the preferred viscosity ranges from 2500 to 250,000 centipoise at 25"C, with a preferred vinyl concentration being from 0.0002 to 0.1% by weight of vinyl concentration of the polymer. Although a polymer having the broad range of vinyl concentration will operate in the present invention, the more limited vinyl concentration would allow for a reaction in which the reaction proceeds at the appropriate rate that is not too slow and yet sufficiently in accordance with the description of the invention and allows the proper cross-linking in the polymer to produce the cured silicone elastomeric foam.With respect to the preferred range of the viscosity, as can be appreciated, it is preferred that the viscosity of the vinyl mixed composition prior to forming the silicone foam be not too high otherwise the composition is difficult to handle and to pour. Accordingly, the low viscosities are preferred for the vinyl-containing polymer in preparing the composition of the instant case.

Accordingly, in accordance with the above description it is preferred that the viscosity of the base vinyl containing polymer vary anywhere from 1000 to 250,000 centipoise or more preferably 2500 to 100,000 centipoise at 25"C. If the viscosity of the base vinyl-containing polymer is kept low then the viscosity of the total composition will also be lower than would be the case with a higher viscosity base vinyl-containing polymer and as such the composition will have a total mixture viscosity that is lower and thus the composition will be easier to handle and pour into the openings in which it is desired to have a silicone foam formed.The preferred formula for the base vinyl-containing polymer is as follows;

where R' is selected from the class consisting of methyl, phenyl and 3,3,3-trifluoropropyl and mixtures thereof varies such that the polymer has a viscosity varying from 100 to 1,000,000 centipoise at 25"C. In the most preferred form of the base vinyl-containing polymer of the instant case, it is preferred that there by only vinyl groups in the siloxy terminal units as disclosed in Formula (3) above. However, it is possible to use a polymer in which there is only vinyl units in the siloxy units in the polymer chain. Thus, there can be produced a silicone foam in which the vinyl units appear only on the siloxane chain and in which there are no vinyl terminating units in the polymer.However, such a base vinyl-containing polymer does not result in a foam with as good physical properties as does the silicone foam produced with a vinyl-containing polymer containing vinyl terminal siloxy units.

In another and more preferred embodiment of the instant case, there can be utilized as the base vinyl-containing polymer, a polymer wherein the vinyl units are both on the terminal positions on the polymer chain as well as on the siloxy units in the polymer chain. While such a polymer will produce an appropriate silicone elastomeric foam such a foam is not as desirable and does not have as good physical properties as when the vinyl terminated base polymer of Formula (3) is utilized above, which is the most preferred polymer for utilization in the process of the instant case. Such vinyl-containing polymers are well-known in the art and can be produced by methods well known in the art.

With respect to the non-fluorinated polymers, such vinyl-containing polymers can be produced by hydrolyzing the appropriate diorganodichlorosilanes in water, then cracking the hydroyzate with an alkali metal hydroxide, preferably KOH, at elevated temperatures to preferentially distill overhead cyclictetrasiloxanes or cyclictrisiloxanes in case of the fluorinated polymers and then taking the cyclictetrasiloxanes and equilibrating them at elevated temperatures, that is, temperatures above 150 C, in the presence of small quantities of potassium hydroxide and also in the presence of the appropriate chain-stoppers. For instance, to produce the polymer of Formula (3) there would be needed to be utilized divinyltetraorganodisiloxane chain-stoppers such as, for instance, divinyltetramethyldisiloxane chain-stopper in the appropriate amounts.

The resulting mixture is heated at temperatures above 150"C and allowed to equilibrate until approximately 85% by weight of the cyclictetrasiloxanes have been converted to the linear polymer of the desired viscosity. At that point the mixture is cooled, the alkali metal hydroxide is neutralized with an appropriate mild acid such as, phospheric acid, and unreacted cyclics are vented off to leave behind the desired vinyi-containing polymer. The appropriate vinyl-containing polymers can be obtained not only for Formula (3), but also with vinyl in the polymer chain by equilibrating the appropriate vinyl-containing cyclictetrasiloxanes. More details are to be found in the production of such vinyl-containing polymers in the foregoing Modic, U.S. Patent 3,425,967 which is hereby incorporated in the present case.The second necessary ingredient in the case are from 1 to 10 parts by weight of an silanol containing silicone compound having the viscosity varying from 1 to 100 centipoise at 25"C with the organic radical is selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, vinyl radicals, aryl radicals and cycloalkyl radicals, fluoroalkyi radicals of 3 to 8 carbon atoms. The polymer has a silanol content varying from 2 to 10 percent weight. More preferably the polymer has a viscosity running from 10 to 100 centipoise and 25"C and a silanol content varying from 5 to 10 percent and more preferably varying from 7 to 10 percent by weight. There are two important aspects of this compound. First there must be a silicone compound and second it must have silanol groups.The silanol groups, along with the hydroxide, produce the hydrogen that forms the blowing ingredient to produce the foam in the composition. Accordingly, any silane or siloxane which has any silanol content within the range as indicated above will function in this system. Accordingly, the silicone compound need not be linear, it may be branch-chained or have any molecular configuration as long as it has silanol groups which are easily condensed. It should be noted that silicone resin will not function as the compound although it has the silanol content since it does not give silanol groups off very easily, and when it does give off silanol groups it condenses to form a hard brittle solid. In the same way, the silanol groups in silica fillers will not function in the instant system as a source of silanol except in a very poor fashion.

Accordingly, any polysiloxane which readily condensable silanol groups can be utilized in this case to react with a hydrogen polysiloxane in the composition to produce hydrogen gas, which acts as a foaming agent to produce a silicone foam in the instant composition. Preferably, the viscosity of the compound is as indicated above; however, the viscosity can be any value so long as it has the above silanol content. The above preferred viscosity values are given in that the organopolysiloxane with the preferred viscosity ranges usually have the silanol content, that is desirable in this composition and preferably a silanol content ranging from 5 to 10 percent by weight. It should be noted that a silanol content of above 10 percent by weight is difficult to obtain in organopolysiloxanes as well as not generally producing any useful results in the composition.However, this is not a critical limitation, any organopolysiloxanes with silanol content of above 10 percent may be utilized in the composition. On the other hand, an organopolysiloxane of a silanol context of less than two percent does not have sufficient silanol to yield a desired amount of hydrogen gas which will act as a foaming agent in the composition. Accordingly, it is highly desirable to have in the composition an organopolysiloxane within the above viscosity ranges and with a silanol content of from anywhere from 2 to 10% by weight and more preferably, 5 to 10 percent by weight. It should be noted that a silicone compound with as low as 2 percent weight will function in the instant composition but will not produce as good as a foam as would be desired.Preferably, the silanol containing silicone compound has a formula,

where R5, R6 is selected from the class consisting of monovalent hydrocarbon radicals, such as vinyl radicals, aryl radicals, and fluoroalkyl radicals and hydroxy groups and mixtures thereof. Tvaries such the viscosity of the polymer base from 10 to 1000 centipoise at 25"C. The compound of formula (4) above is a linear compound and is preferred as the silanol compound within the scope of the invention. However, as previously stated silanol containing polysiloxane may be utilized with equal facility in the instant composition. R5, R6 radicals may be selected from halogenated monovalent hydrocarbon radicals, such as the radicals given for R and R' radicals of the vinyl containing polymer of formula 1.This is true also for the definition of the organic group in the silanol containing silicone compound in which the polysiloxane of formula (7) is within the scope of such that organic groups can be the same as the vinyl-containing polysiloxane of Formula (1).

The polysiloxane is present at a concentration of 1 to 10 parts weight per 100 parts be weight of a base vinyl containing polymer of Formula (1). Less than 1 part does not result in the release of sufficient gas that produce good foam. More than 10 parts serves no useful purpose and is a waste of the silanol material.

Further, more than 10 parts by weight of silanol containing polysiloxane produces too much hydrogen gas that may result in large voids in the system. More preferably there is utilized from 1 to 5 parts by weight of the silanol containing polysiloxane as identified previously. The third necessary ingredient in the composition in this case, is from 1 to 50 parts by weight of a hydride polysiloxane of the Formula (2) above.

Here the third ingredient that is necessary in the composition of the instant case is that there must be present from 1 to 50 parts by weight of the hydride polysiloxane of Formula (2) above, where R2 is selected from the class consisting of hydrogen, alkyl radicals of 1 to 8 carbon atoms, aryl radicals and fluoroalkyl radicals of 3 to 8 carbon atoms, and R3 is selected from alkyl radicals, aryl radicals of up to 8 carbon atoms, where the hydride polymer has the hydrogen content varying from 0.3 to 1.6% by weight and z andy varies such that the polymer has a viscosity varying from 5 to 100 centipoise at 25"C. It should be noted that the other limitation above is that the hydrogen content of the hydride polysiloxane polymer varies from 0.3 to 1.6% by weight.Of necessity, the limitation must be met, otherwise, the hydride polymer will not have enough hydrogen atoms to react with water to liberate the hydrogen also add and cross-link with the vinyl molecules of the vinyl-containing polysiloxane to form the cured silicone foam. If there is not enough hydride in the polymer, that is, the 0.3% lower limitation by weight, then there will not be sufficient hydrogen in the polymer to cross-link with the vinyl containing polymer.

Accordingly, the hydrogen content of such polymer must be observed strictly as the amount of moles of water per mole of hydrogen polysiloxane cross-linking agent. It should be noted also that the viscosity is quite important and that y varies such that the viscosity of the polymer varies from 5 to 100 centipoise and more preferably from 5 to 40 centipoise. It should be noted that hydride containing polysiloxanes of a higher viscosity and molecular weight may be utilized, however, such polymers are difficult to obtain and difficult to utilize with the appropriate hydride content for use in the instant invention. The reason for the above is that for the reaction of the instant invention to proceed in accordance with the disclosure, it is necessary that the hydride polymer of Formula (3) contain hydrogen on the siloxane chain.Although it may contain hydrogen atoms on a terminal siloxy atom, it must contain hydride atoms on the polymer chain in order for the reaction of the instant case to operate. If there are no hydrogen atoms in the polymer chain of the hydride polymer, then a proper silicone foam in not obtained. Accordingly, a hydride polymer of the instant case with only hydrogen atoms on the terminal siloxy atoms will not work to form a silicone foam in the composition of the instant case.

In accordance with the above and as limited above, R2 may be selected from the class consisting of hydrogen and any hydrocarbon radical and halogenated hydrocarbon radical normally associated with polysiloxane polymers, preferably, other than aliphatic unsaturated radicals. Accordingly, the R2 radical may preferably be selected from any alkyl radicals such as, methyl, ethyl, propyl; cycloalkyl radicals such as, cyclohexyl, cycloheptyl, etc.; mononuclear aryl radicals such as, phenyl, methylphenyl, ethylphenyl, etc; halogenated hydrocarbon radicals such as, fluoroalkyl radicals, 3,3,3-trifluoropropyl, etc.Most preferably, the R2 radical is selected from the class consisting of hydrogen, alkyl radicals of 1 to 8 carbon atoms, aryl radicals of 6 to 8 carbon atoms and fluoroalkyl radicals of 3 to 8 carbon atoms, and most preferably R2 is selected from methyl, phenyl and 3,3,3-trifluoropropyl radicals. The R3 radical is selected from alkyl and aryl radicals of up to 8 carbon atoms. It is desirable that the vinyl-containing polymer not contain any hydrogen substituent groups and in the hydrogen polysiloxane polymer of Formula (2) there by no vinyl or aliphatic unsaturated substituent groups. It should be noted there is preferably used from 1 to 50 parts by weight of hydride polysiloxane cross-linking agent of Formula (2), per 100 parts of base vinyl-containing polymer of Formula (1) above.The production of the hydrogen substituted polysiloxane polymer which is nonfluorinated is much simpler than the foregoing production of the vinyl-containing polymer. Such low viscosity hydride substituted polysiloxane polymers are basically obtained by hydrolyzing the appropriate hydride substituted dichlorosilanes with diorganodichlorosilanes with the appropriate amount of chainstoppers, whether they be hydride substituted or not.

Both in the production of vinyl-containing polymers of Formula (1), as well as in the production of the hydride polymer, the appropriate substituted chain-stopper may be any disiloxane, trisiloxane or low molecular weight linear polymer. With respect to the hydrolysis reaction in the production of the hydride polysiloxane polymer then there is utilized as chain-stoppers a monofunctional silane having the appropriate substituent groups such as, hydrogen dimethylchlorosilane, trimethychlorosilane, 3,3,3 trifluoropropyldimethylchlorosilane. Accordingly, such chain-stoppers which are chlorosilanes having the appropriate substituent groups may be utilized to form the low viscosity and low molecular weight hydride polysiloxane polymer cross-linking agent of Formula (2).

It is also possible to make such low molecular weight polymers by equilibrating the appropriate cyclictetrasiloxanes with a very mild acid catalyst such as, acid activated clay, such as the foregoing Filtrol with the appropriate chain-stoppers.

It should also be noted that in such equilibration procedures which are carried out at elevated temperatures with an acid catalyst they preferably carried out at temperatures above 90"C, and more preferably above 1 OO"C to equilibrate the cyclictetrasiloxanes and form and convert about 85% of the cyclictetrasiloxanes to the linear polymer whereupon the acid catalyst is removed by filtration and the cyclics are vented off to give the desired linear polymer.

With fluorinated polymers a slightly different procedure is utilized to produce such florinated polymers. In the case of the vinyl-containing base polymer of Formula (1), the appropriate fluorinated cyclictetrasiloxanes are equilibrated with chain-stoppers in the presence of certain basic catalysts such as, cesium hydroxide, potassium silanolate, at temperatures about 90"C, or slightly above to produce at anywhere from 50 to 60% conversion of the linear polymer at viscosities at least up to 1,000,000 centipoise at 25"C, wherein the catalyst is then neutralized with a mild acid and the cyclics are vented off to give the fluorinated polymer.The fluorinated cyclictetrasiloxanes are obtained by hydrolyzing the appropriate fluorinated dichlorosilane and then cracking the hydrolysate with KOH and obtaining as much of the pure tetrasiloxanes as possible.

However, another preferred method of producing such fluorinated polymers, that is, a vinyl-containing polysiloxane polymer of Formula (1), which is fiuorinate substituted is to crack the hydrolyzate with KOH and preferentially distiil overhead the fluorinated cyclictrisiloxanes which are produced in greater quantities than the fluorinated cyclictetrasiloxanes by careful fractionation. The fluorinated cycl ictetrasiloxanes when equilibrated with an alkali metal hydroxide catalyst are converted to the high viscosity or low viscosity fluorinated substituted polymer.Such cyclictrisiloxanes can be also equilibrated in the presence of a mild base catalyst to form fluoro-substituted linear fluids, that is, materials having viscosities in the area of 1000 to 10,000 centipoise of viscosity at 25"C or less. A fuller disclosure as to the production of such fluorine substituted polymers used in SiH-olefin addition reactions is to be found in Jeram, U.S. Patent 4,041,010, which is incorporated herein by reference. For the purpose of the instant case, if it is desired to obtain a fluorine-substituted hydride polysiloxane polymer within the scope of Formula (2), it can be obtained by direct hydrolysis of the appropriate fluoro-substituted chlorosilanes.Finally, in the process of the instant case there is utilized generally from 1 to 250 parts per million of a platinum catalyst and more preferably 1 to 200 parts per million of a platinum catalyst. It is more preferred to utilized a stabilized platinum complex in the process of the instant case since it disperses in the ingredients much more easily and as such results in faster reaction time.

Many types of platinum compounds for this SiH-olefin addition reaction are known and such platinum catalysts may be used also for the reaction of the present case. The preferred platinum catalysts especially when optical clarity is required are those platinum compound catalysts which are soluble in the present reaction mixture. The platinum compound can be selected from those having the formula (PtCI2.Olefin)2 and H(PtCIB.Olefin) as described in U.S. Patent 3,159,601, Ashby. The olefin shown in the previous two formulas can be almost any type of olefin but is preferably an alkenyl having from 2 to 8 carbon atoms a cycloalkenyl 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, cycloheptene, etc.

Afurther platinum containing material usable in the composition of the present invention is the platinum chloride cyclopropane complex (PtCI2.C3H6)2 described in U.S. Patent 3,159,662, Ash by. Still, further the patent containing material can be a complex formed from chloroplatinic 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 3,220,972, Lamoreaux.

All the patents and patent applications mentioned in this present specification are incorporated into the present application by reference.

The preferred platinum compound to be used not only as a platinum catalyst but also as a flame retardant additive is a platinum divinyltetramethyldisiloxane complex as disclosed in U.S.P. 3,775,452, Karstedt.

Generally speaking, this type of platinum complex is formed by reacting chloroplatinic acid containing 4 moles of water of hydration with tetramethyldivinylsiloxane in the presence of sodium bicarbonate in an ethanol solution.

It can be appreacted that, as stated previously, many types of platinum catalysts can be utilized in the process of the instant case to produce a silicone foam since the compositions of the instant case are not as sensitive to a particular type of platinum catalyst as was the case with the prior art compositions. However, a preferred platinum catalyst within the scope of the instant case is either the Lamoreaux catalyst disclosed in the foregoing patent set forth above or the Karstedt platinum catalyst set forth in the disclosure hereinabove.

The Karstedt platinum catalyst which is the one preferred catalyst within the scope of the instant case, comprises reacting chloroplatinic acid with a vinyl-containing cyclotetrasiloxane or a vinyl-containing low molecular weight polysiloxane in the presence of an alcohoi and a mild base such as, sodium bicarbonate, such that the platinum complex is substantially chlorine free. Such a catalyst, because of its reactivity, can be used with advantage in the compositions of the instant case. The advantage of the platinum catalyst, such as the Karsteadt platinum complex catalyst within the scope of the instant case, is that it is so reactive that the foam is formed at a good rate and hydrogen gases liberated at a good rate so that the desired low density is formed in a faster manner than is the case when other types of platinum catalyst are used.

It should also be noted that platinum complexes formed between chloroplatinic acid and a vinylcontaining siloxane material can also be used as a catalyst in the process in compositions of the instant case, irrespective of whether they are chlorine free. However, a platinum complex catalyst which is obtained by reacting a vinyl-containing siloxane with a chloropiatinic acid and in which the chlorine content is substantially reduced is a catalyst with different properties and is more advantageously utilized in the production of the silicone foams of the instant case.

There are other types of solubized platinum catalyst that can be utilized in this case. Unlike the compositions of the Dow Corning, Smith patent, the compositions of the case are not sensitive to particular type of solubilized platinum catalyst. It is preferred that solid platinum catalyst such as platinum with charcoal not be utilized in the instant invention since they do not produce as good as foam as solubilized platinum catalyst. However, with this caveat any type solubilized can be utilized in the instant case. The more preferable is the Karstedt platinum catalyst as explained previously since that this is a very rapid reacting catalyst which produces a good foam. With all of these ingredients, they may be produced a silicone foam.

Generally, what comprises is that the vinyl polymer is stored separately from the hydrogen polysiloxane.

The platinum catalyst may be either with the vinyl or with the silanol compound and vinyl containing polysiloxanes. When the hydride is mixed with silanol-polysiloxane and the vinyl containing polysiloxane in the presence of the platinum catalyst, the resulting composition will release hydrogen to form a silicone elastomeric foam. It should be noted that there may be utilized inhibitors in the composition such that there may be formed a one component reactive system which will not react at room temperature for substantial period of time up to several months but will react at elevated temperatures, that is temperatures at above 100 or 150"C in a matter of seconds to produce a good silicone foam.Accordingly, there may be utilized an inhibitor in the composition which may for instance be vinyl containing organopolysiloxane such as methyl vinyl cyclotetrasiloxane. It may also be triallyl isocyanurate and a dialkyl maleate. Examples of the use of the maleate is to be found in the patent application of Richard P. Eckberg, Docket 60 Sl-202 Entitled "Solventless Paper Release Compositions".

The inhibitor may be used at a concentration of anywhere from 100 parts per million to 10,000 parts per million based on a total composition; however, the above ranges are only preferred ranges since any desired ranges may be utilized depending on how much inhibitor activity is desired. It can be appreciated that when too much of the inhibitive compound is included, then it may have adverse effects on the physical properties of the composition or it may be difficult to initiate the reaction even at elevated temperatures as can be appreciated. But generally the inhibitor compounds can be utilized in the range as indicated above. The inhibitor compounds are not utilized when it is desired to mix the composition and produce a silicone elastomeric foam in a matter of minutes or even seconds in a factory production facility.When the silicone foam is to be produced in situ in electric conductor containing conduits in nuclear plants and other buildings, then it is preferred that such inhibitor compounds not be utilized and the the foam produced by mixing the two packages or components together at room temperature to produce the silicone elastomeric foam. It also may be desired to form a one component system by having an inhibitor present and mix all the ingredients together and have the inhibitor present to prevent a reaction of the ingredients until it is desired to initiate the reaction and then simply by heating the resulting one component system at elevated temperatures a silicone foam is produced. It also can be appreciated that the silanol containing the polysiloxane may not be a polysiloxane, it may also be a silane.Thus the silanol containing the silicone compound that is necessary for the present composition to form hydrogen containing polysiloxane maybe a silanol containing siiane which has the desired silanol content such as up to 33% by weight of silanol and as such it may function as the distributor of silanol in the composition in the concentrations of 1 to 10 parts, more preferably 1 to 5 parts per 100 parts of the base vinyl containing polymer in a composition to react with hydrogen polysiloxane to release hydrogen gas for producing the silicone foam. However, the silanol containing polysiloxane is preferred over silanol containing silane in the instant composition since the silanol containing polysiloxanes forms and release hydrogen gas the foaming gas in a more controlled manner.However, either silanol containing silanes or polysiloxanes may be utilized in the instant application. That is any silanol containing silane being free of hydride and having up to two hydroxy groups per molecule where the other subsequent groups and the silicone groups are saturated monovalent halogenated hydrocarbon radicals such as alkyl radicals, 1 to 8 carbon atoms, vinyl radicals, aryl radicals and cycloalkyl radicals may be utilized in the instant composition.

These compositions are specified above are good compositions for foaming silicone elastomeric foams.

However, it has been desired to produce such compositions which have strength. The slicone foam of the above basic composition is a good elastomeric form but does not have desirable strength to take abrasive wear and roughness such as for instance in a ceiling application or in a dashboard application. Such abrasive resistant properties and toughness properties are desirable in the silicone foam in the instant case because it would have both flame retardentness and toughness. Accordingly, one way the toughness of such silicone elastomeric foam may be increased is by incorporating a filler in the composition. Accordingly, there may be incorporated anywhere from 0 to 200 parts by weight of a filler.

It should be noted that extending fillers are preferred since reinforcing fillers such as fumed silica and precipitated silica when incorporated into the composition in any concentration unduly increase the viscosity of the composition, thus, making it difficult to handle and to pour. However, fumed silica and precipitated silica have the advantages of increasing the physical properties, that it, the tensile strength, as well as the tear of the silicone elastomeric foam that is formed from the composition.

Accordingly, the more preferred embodiment of the instant case there is utilized from 10 to 100 parts of filler based on 100 parts of the vinyl-containing base polymer.

It should be noted that all the concentration of ingredients set forth in the instant case are based per 100 parts of the base vinyl-containing polymer. Accordingly, there may be utilized in the preferred embodiment anywhere from 10 to 100 parts of a filler selected from the class consisting of reinforcing fillers and extending fillers and, more preferably, just extending fillers. A preferred extending filler that may be utilized in the instant composition which does not unduly increase the viscosity of the uncured composition is ground quartz. Ground quartz has the additional advantage that to some extent it increases the burn resistance properties of the cured silicone foam that is produced from the composition.Other extending fillers that may be utilized in the instant compositions are, for instance titanium dioxide, lithopone, zinc oxide, zircomium silicate, silica aerogel, iron oxide, diatomaceous earth, calcium carbonate, glass fibers, magnesium oxide, chromic oxide, zirconium oxide, aluminum oxide, alpha quartz, calcined clay, carbon graphites, etc.

It should be noted if reinforcing fillers are used such as, fumed silica and precipitated silica, that in order to keep the viscosity increase in the composition as low as possible, such filler even the extending fillers may be treated, for instance, with cyclicpolysiloxanes or silazanes. The disclosure in which silica fillers may be treated, for instance, with cyclicpolysilixoanes is set forth in U.S. Patent 2,938,009, Lucas, which is hereby incorporated by reference. However, such is only one method of treating reinforcing fillers and other methods with other agents are also available in the art.

Another method of treating reinforcing fillers is, for instance, to be found in Brown, U.S. Patent 3,024,126, disclosure of which is hereby incorporated by reference; Smith, U.S. Patent 3,635,743 and Beers, U.S. Patent 3,837,878. Such ingredients such as, cyclicpolysiloxanes, may also be utilized to treat extending fillers such as, ground quartz, with some advantage since such treatment does also alleviate the viscosity increase by extending fillers. However, as stated previously, the most preferred filler for utilization to produce silicone foam of the instant case, is ground quartz. Quartz enhances the burn resistant properties of the composition as well as imparting some enhanced physical properties to the final cured silicone foam.As can be appreciated to increase the strength properties of the instant composition, there may only be incorporated fillers into the composition but there may be incorporated into the composition burn resistant fillers to increase the burn resistant of flame retardant properties of composition. The only trouble with the silica filling is that when incorporated in large quantities in the silicone composition they tend to increase the uncured viscosity of the composition making it difficult to pour and mix. One method of avoiding this is to treat the filler with silanes and polysilixoanes is disclosed above. Another method is to utilize in the composition a fiberous filler.One examples of a fiberous fillers that may be utilized in the instant composition per 100 parts of the base vinyl containing polymer that may incorporate from 10 to 100 by weight of inorganic fiberous material such as potasium titantate as disclosed in U.S. Patent 3,425,967. The most desirable fiberous filler which increases the toughness of the composition but does not decrease from the burn resistance or flame retardance is, of course, the potasium titanate. In place of these fillers, they may also be utilized a silicone resin as a filler in the composition to increase the toughness and tensile strength of the composition without unduly increasing the viscosity of the composition in the uncured state and without detracting from the flame-retardant properties of the composition.Accordingly, per 100 parts of the base vinyl containing polymer of Formula 1, it may be incorporated into the composition 10 to 100 parts by weight over organopolysiloxane having R SiO units and Si 2 units where R7 is a radical selected from the class consisting of vinyl radicals, and monovalanet hydrocarbon radicals where the ratio of mono units to titra units from .5:1 to 1:1 and where from about 2.5 to 10 mole percent of the silicone atoms contain silicone-bonded vinyl groups. The above formulation is of a silicone resin composed of monofunctional and tetrafunctional units and the desirability for the silicone resin to have vinyl groups is so that it will be compatible with a vinyl containing polymer and be dispersible in it and also so that it will cure into the system.More preferably the R7 is a monovalent hydrocarbon radical selected from the class consisting of alkyl radicals of to 8 carbon atoms, aryl radicals of up to 8 carbon atoms, vinyl radicals, fluoro alkyl radicals of 3 to 8 carbon atoms and so forth, most preferably the R7 selected from alkyl radicals of 1 to 8 carbon radicals, phenyl radicals, vinyl radicals, with the resin must have the desired vinyl substitution as pointed out previously. The method of producing such resin is well-known in the art. Generally, the method comprises taking corresponding monofunctional trimethylsilane and tetrachlorosilane and adding the silanes to water in the presence of a water immersible solvent.The resulting mixture is hydrolized to produce a silicone resin which is separated or congregates in the water immiscsible organic solvent such as toluene or xylene; and then is separated from the hydrolysis mixture and purified of acid by repeated washings with water. The resulting resin in the solvent may then be added to the vinyl polymer and mix in whereupon the solvent is simply evaporated to yield the mixture of the resin in the composition. Accordingly, with this additive it is possible to prepare a silicone foam composition not having any fiberous or silica fillers and the reinforcement problems of fillers and yet be a tough silicone elastomeric foam with abrasion resistant properties and toughness suitable for making the silicone foam padding.It should be noted that the vinyl containing silicone resin can be incorporated with the vinyl containing polymer so it can be more easily dispersed. Most preferably the vinyl containing resin composed of monofunctional and tetra-functional units is incorporated into the vinyl containing polymer in a solvent solution of the silicone resin to produce a mixture there of whereupon the solvent is evaporated to result in the mixture of the two components which can form one component of the two package system. It should be noted that less than 10 parts by weight of the resin per 100 parts of the base vinyl containing polymer does not produce significant results and more than 100 parts by weight does not produce any significate improvements over the lesser amounts.In additional when there is more of the resin than there is of the base polymer, mixing becomes quite difficult of the composition. Additionaily, there may be mixed into the composition another type of resin composed of monofunctional units, difunctional units, tetrafunctional units. This type of resin which also has difunctional units over the first type of silicone resin composed of only monofunctional and tetra-functional siloxy units is another type of resin that is utilized in the instant composition. There are no extra benefits to be obtained by utilizing this second resin containing difunctional siloxy units except that this type of resin has more of an elasticizing effect on the composition and also allows incorporation of a higher amount of vinyl in the resin to be incorporated into a base-vinyl containing polymer. Accordingly, per 100 parts of a base-vinyl containing polymer there may be incorporated 10 to 100 parts by weight of a silicone resin polysiloxane polymer comprizing (R7)3 SiO0.5 units, R7SiO units and SiO2 units R7 is monovalent hydrocarbon radical where the ration of monofunctional units is from about 0.5:1 to 1:1 and the R7SiO units are present in the amount equal to from about 1 to 10 mole percent based on the total number of moles of silicone units in the copolymer and where from about 2.5 to 10 mole percent of the silicone atoms contain silicone bonded vinyl groups. Accordingly, the only difference in this resin from the previous resin in the presence of di-functional siloxy units.Again, the R7 radical in the above units of this second resin containing difunctional siloxy units may be any of the radicals given for the R7 symbol in the definition of the resin composed of solely monofunctional units and tetrafunctional units. Most preferably R7 in the above resin is selected from alkyl radicals of 1 to 8 carbon atoms and vinyl radicals. In any case the resin must have the foregoing concentration of vinyl units in the resin, in the foregoing radicals of monofunctional units and tetrafunctional units and difunctional siloxy units to the total units as discussed above. Again, the necessity for having certain vinyl concentration is for the ease of dispersing the resin in a base-vinyl containing polymer and curing the silicone resin into the final silicone foam composition.This resin is produced much the same as the previous resin the only difference being that the silanes in the reaction mixture is of the desired propertions are di-functional chlorosilanes reacting along with the monofunctional chlorosilanes and tetrachlorosilanes. It should be noted that the reactants that hydrolyzed in the hydrolysis mixture are in relative proportion to each other, that it is desired to have to different functional units in the final silicone resin product. Accordingly, by utilizing such silicone resins, it is possible to produce a true silicone foam without the necessity of using silica fillers and without the necessity of using fiberous fillers and without also undue increase of viscosity of the composition. However, by utilizing fiberous fillers in addition to the resin it is possible to obtain an extremely tough silicone foam composition.It should be noted that the vinyl containing resin does not detract from the flame retardant properties of the composition while inhancing the tensile strength and toughness of the cured silicone foam. It should be noted there must be at least one mole of silicone SiH per mole of silanol to produce a desirable foam, more preferably there is present from 2 to 5 mole percent of SiH per mole of silanol in final composition. By silanol it is meant to refer to the silanol content of the silanol containing silicone compound while the SiH refers to the SiH concentration in the hydride polysiloxane of Formula 2. If there is less than one mole of SiH compound per mole of silanol groups in the final mixture, then sufficient hydrogen gas will not be liberated to give a good foam.If there is more than the preferred then the results may be a suitable foam; however then there will be too much hydrogen gas given off and also there will be uncured or unused hydride in the final silicone foam composition which may detract from the physical properties in the flame retardent properties of the cured silicone foam composition. Accordingly, it is highly desirable that there be at least 1 mole of SiH in the silicone hydride per mole of silanol group in the silanol containing silicone compound as defined previously.

To enhance the burn resistance of flame retardent of the silicone foam, additional ingredients may be added. For instance, per 100 parts of the base vinyl containing polymer of formula 1, there may be added from anywhere from .1 to 10 parts of carbon black and more preferably a carbon black that is low in residual sulfur. Such carbon blacks which are low in sulfur produce the best flame resjstant properties in this composition. More preferably there may be utilized anywhere from .5 to 2 parts of a low residule sulfur content carbon black per 100 parts of the base vinyl containg polymer. It is noted that the additional amount of carbon black above 2 parts does add burn resistant properties but not to such a great extent.Accordingly, the preferred range of carbon black utilized in the composition of the instant case as to impart burn resistant properties the composition is from .5 to 2 parts carbon black. Although .2 parts of low residule sulfuric carbon black will impart some burn resistant properties for the composition it is desirable that it be utilized in concentration of .5 parts to obtain the most desirable burn resistant or flame resistant properties.

It should be appreciated that the flame retardant properties of the silicone foam of the instant composition is further improved in the composition by adding other well known flame retardant additives so long as they do not interfere with the basic reactions to produce the silicone foams of the instant case and so long as they do not inhibit or poison the platinum catalyst in the SiH Olefin platinum catalyst reactions of the instant case.

The composition will normally be prepared in the form of two packages where the hydride is kept separate and is not included with the platinum catalyst.

Preferably the vinyl silicone materials and the silanol silicone materials are packaged together with or without the platinum catalyst and hydropolysiloxane is paged separately without the platinum catalyst.

When the two packages are mixed they will react in room temperature in the absence of inhibitors to form a silicone elastomeric foam. By utilizing inhibitors it may be possible to mix the components and retard the formation of a silicone foam for substantial periods of time depending on the inhibitor but when such a composition is heated at elevated temperatures it will cure in the matter of minutes and even seconds to form a silicone elastomeric foam. Accordingly, it is made possible by the use of inhibitors to make one component systems.

The examples below are given for the purpose of illustrating the present invention and not given for the purpose of setting boundaries to the instant case. All parts in the examples are by weight.

Example 1 There was prepared a mixture of 49.4 parts of a 72:28 blend of vinyl terminated dimethylpolysiloxanes having a viscosity of 3500 gs. at 25"C for the 72% component and 80,000 gs. for the 28% component. The low viscosity component had approximately 0.0015% vinyl while the high viscosity component had approximately 0.0005% vinyl. To this there was added 7 parts of 5 micron quartz; 0.6 parts of carbon black; 12.5 ppm platinum in the form of the Karstedt catalyst; 1 gram of linear di methyl polysiloxane containing 7.3% silanol and .09 parts of methyl vinyl -cyclotetrasiloxane to which there was added two parts of hydrogen linear polysiloxane containing 1.5 percent of silicon hydride and having the viscosity of 18 centipoise at 25"C.

Within two minutes the system started to form a gel. A flame retardant foam was obtained which had a specific gravity of 0.48. In this example the silanol containing polysiloxane represented only 2 percent of siloxanes. The mole ratio of SiH/SiOH was 6.99.

Example 2 There was prepared a mixture of 46.8 parts of the same blend of vinyl containing polysiloxanes such as in Example 1 in which there was added 6.6 parts of 5 micron quartz; .6 parts of carbon black; 12.5 ppm platinum as the Karstedt catalyst; 2 parts of a linear silanol containing polysiloxane of Example 1 containing 7.3% of silanol and having a viscosity of 26 centipoise at 25"C and .09 parts of methyl vinyl tetramer to which there was added 3.7 parts of hydropolysiloxane having the viscosity of 18 centipoise at 25"C and a hydride content of 1.5% by weight. Again there was formed a flame retardant foam having a specific gravity of .38. The percent of hydroxylated siloxanes was approximately 4% of the combined hydroxylated and vinyl siloxanes.

Example 3 To 50 parts of a composition containing 75 percent by weight a vinyl chain stopped polydimethylsiloxane having a viscosity of 80,000 cps and 25 percent by weight of an organosiloxane coppolymer comprising trimethylsiloxane units, methyl vinyl siloxane units and SiO2 units with a ratio of 0.8 trimethylsiloxane units per SiO2 unit and with the methyl vinyl siloxane being present in an amount such that 7.0 mole percent of the silicone atoms were present as methyl vinyl siloxane units.

The above mixture was catalyzed with 30 ppm platinum in form of the Karstedt catalyst to which there was added 3.3 parts silanol containing polysiioxane in Example 1 and 1.5 parts of a trimethyl chain-stopped polymethylhydrogensiloxane having 1.5 present hydrogen and a viscosity of 18 centipoise at 25"C. An extremely tough foam resulted having a specific gravity of 0.35 was found.

Example 4 To 33.5 parts of polysiloxane composition described in Example 3, there was added 16.5 parts of a quartz filler and 20 ppm platinum in the form of the Karstedt catalyst based on weight of the polysiloxanes. This composition had a specific gravity of 1.28. There was added 0.25 parts of water. To this there was added 3.3 parts of hydrogenpolysiloxane of Examples 1 and 2. After vigorous mixing foaming took place to a very tough resilient foam having a specific gravity of .31.

To the composition described in Example 3, was added 1 percent of TAIC, Trialkyi isocyanurate, as a room temperature cure inhibitor before the addition of the polymethylhydrogensiloxane. When the polymethyl hydrogensiloxane was added, no reaction was observed at room temperature, the system remained a viscous fluid. Upon heating for 15 minutes at 150"C, the system cured and foamed to produce a resilient foam having a specific gravity of 0.41.

Claims (32)

1. A silicone composition capable of being formed and having burn resistant properties comprising, (a) 100 parts by weight of a base vinyl containing polymer of the formula,

where R and R' are selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, aryl radicals, vinyl radicals and fluoroalkyl radicals of 3 to 8 carbon atoms, such that the polymer contains from 0.0002 to 3% by weight, vinyl and x varies such that the viscosity of the polymer rises from 100 to 1,000,000 centipoise at 250"C;; (b) from 1 to 10 parts by weight of silanol-containing silicone compound having a viscosity varying from 10 to 1000 centipoise at 25"C where the organic group is selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, vinyl radicals, aryl radicals, and fluoroalkyl radicals of 3 to 8 carbon atoms such that the polymer has a silanol content varying from 2 to 10%; (c) from 0 to 200 parts by weight of a filler; (d) from 1 to 50 parts by weight of a hydride polymer of the formula,

when R2 is selected from the class consisting of hydrogen, alkyl radical of 1 to 8 carbon atoms, aryl and fluoroalkyl radicals of 3 to 8 carbon atoms and R3 is selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, aryl radicals and fluoroalkyl radicals of 3 to 8 carbon atoms where the hydrogen polymer has a hydrogen content varying from 0.3 to 1.6% by weight andy varies such that the polymer has viscosity varying from 5 to 100 parts at 25"C when there is also at least 1 mole of SiH per mole of silanol; and (c) from 1 to 250 parts per million of a platinum catalyst.

2. The silicone composition of Claim 1 wherein the vinyl containing polysiloxane has the formula,

where Vi is vinyl, R' is selected from the class consisting of methyl, phenyl, and 3,3,3 trifluoropropyl and v varies such that the viscosity of the polymer varies from 100 to 1,000,00 centipoise at 250C.

3. The composition of Claim 1 where there is present from 10 to 100 parts of a filler selected from the class consisting of reinforcing filler and extending fillers.

4. The composition of claim 3 wherein the filler is ground quartz.

5. The composition of claim 1 wherein there is present from 0.1 to 10 parts of carbon black.

6. The composition of claim 1 wherein there is present from 100 to 100,000 parts per million of an inhibitor.

7. The composition of claim 6 wherein the inhibitor is selected from the class consisting of a vinyl-containing organocylcosiloxane, trialkyl cyanurate, alkyl maleate and mixtures thereof.

8. The composition of claim 1 where the hydride polymer has the formula,

where R3 is selected from the class consisting of methyl, phenyl, and 3,3,3-trifluoropropyl and mixtures thereof.

9. The composition of claim 1 wherein the platinum catalyst is a complex of platinum and a vinyl-containing polysiloxane.

10. The composition of claim 1 wherein there is further present from 1 to 100 parts by weight of a silicone filler material.

11. The composition of claim 1 wherein there is further present from 10 to 100 parts by weight of an organopolysiloxane copolymer comprising (R7)3 SiO06 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.

12. The composition of claim 1 wherein there is further present from 10 to 100 parts by weight of an organopolysiloxane copolymer comprising (R7)3SiOo 5 units, R7SiO units and SiO2 units where R7 is a radical selected from the class consisting of vinyl radicals, aryl radicals, alkyl radicals and fluoroalkyl radicals where the ratio of monofunctional units to difunctional units is from about 0.5:1 to 1:1 and the difunctional units are present in an amount equal to from about 1 to 10 mole percent based on the total number of mole siloxane units in the copolymer and where from about 2.5 to 10 mole percent of the silicone atoms contain silicone-bonded vinyl groups.

13. The composition of claim 1 where the silanol containing silicone compound has the formula,

where R5, R6 is selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, vinyl radicals, aryl radicals and fluoroalkyl radicals and hydroxy groups and mixtures thereof where t varies such the viscosity of the polymer varies from 10 to 1000 centipoise at 25"C.

14. A process for producing a silicone composition capable of being foamed, having burn-resistant properties comprising (1) mixing (a) 100 parts by weight of a base vinyl containing polymer of the formula,

where R and R' are selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, aryl radicals, vinyl radicals and radicals of 3 to 8 carbon atoms, such that the polymer contains from 0.0002 to 3% by weight, vinyl groups and x varies such that the viscosity of the polymer rises from 100 to 1,000,000 centipoise at 250"C;; (b) from 1 to 10 parts by weight of silanol containing silicone compound having a viscosity varying from 10 to 1000 centipoise at 25"C where the organic group is selected from the class consisting of alkyl radical of 1 to 8 carbon atoms, vinyl radicals, aryl radicals, cycloalkyl radicals and fluoroalkyl radicals of 3 to 8 carbon atoms such that polymer has a silanol content varying from 2 to 10% by weight; (c) from 0 to 200 parts by weight of a filler; (d) from 1 to 50 parts by weight a hydride polymer of the formula,

where R2 is selected from the class consisting of hydrogen, alkyl radicals of 1 to 8 carbon atoms, aryl radicals and fluoroalkyl radicals of 3 to 8 carbon atoms and R3 is selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, aryl radicals and fluoroalkyl radicals of 3 to 8 carbon atoms where the hydrogen polymer has a hydrogen content varying from 0.3 to 1.6% by weight andy varies such that the polymer has viscosity varying from 5 to 100 at 25"C when there is also at least 1 mole of SiH per mole of silanol; and (c) from 1 to 250 parts per million of a platinum catalyst; (d) allowing the mixture to foam and cure to an elastomeric foam.

15. The process of claim 14 wherein the mixture is allowed to foam at room temperature.

16. The process of claim 14 wherein the base vinyl-containing polymer has the formula,

where Vi is vinyl, R' is selected from the class consisting of methyl, phenyl, and 3,3,3-trifluoropropyl and varies such that the viscosity of the polymer varies from 100 to 1,000,000 centipoise at 25"C.

17. The process of claim 14 wherein there is present from 10 to 1000 parts of a filler selected from the class consisting of reinforcing fillers and extending fillers.

18. The process of claim 17 wherein the filler is ground quartz.

19. The process of claim 14 wherein there is present from 0.1 to 10 parts of carbon black.

20. The process of claim 14 wherein there is present from 100 to 100,000 parts per million of inhibitor.

21. The process of claim 20 wherein the inhibitor is selected from the class consisting of vinyl-containing organocyclotetrasiloxane, trialkyl cyanurate, alkyl maleate, and mixtures thereof.

22. The process of claim 1 where the hydride polymer has the formula,

where R3 is selected from the class consisting of methyl, phenyl, and 3,3,3-trifluoropropyl and mixtures thereof.

23. The process of Claim 1 wherein the platinum catalyst is a complex of platinum and a vinyl-containing polysiloxane.

24. The process of Claim 13 wherein there is further present from 10 to 100 parts by weight of a fiberous filler material.

25. The process of Claim 14 where there is further present from 10 to 100 parts by weight of an organopolysiloxane copolymer comprising (R7)3 SiO05 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 about 0.5:1 to 1:1 and where from about 2.5 to 10 mole percent of the silicone atoms containing silicone bonded vinyl groups.

26. The process of Claim 14 wherein there is further present from 10 to 100 parts by weight of an organopolysiloxane copolymer uprising (R7)3 SiO05 units, R7SiO 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 mono-functional units to tetrafunctional units is from about 0.5:1 to 1:1 and the difunctional units are present in an amount to equal to from about 1 to 10 mole percent based on the total number of mole 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.

27. The process of Claim 14 where the silanol containing compound has the formula.

where R5, R6 is selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, vinyl'radicals, aryl radicals and fluoroalkyl radicals and hydroxy groups and mixtures thereof where t varies such the viscosity of the polymer varies from 10 to 1000 centipoise at 25"C.

28. A process for insulating from fire an electrical system by enclosing an electrical system in a burn-resistant foam comprising (1) mixing (a) 100 parts by weight of a base vinyl containing polymer of the formula,

where Rand R' are selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, aryl radicals, vinyl radicals and fluoroalkyl radicals of 3 to 8 carbon atoms, such that the polymer contains from 0.0002 to 3% by weight, vinyl and x varies such that the viscosity of the polymer rises from 100 to 1,000,000 centi poise at 25"C;; (b) from 1 to 10 parts by weight of silanol containing silicone compound having a viscosity varying from 10 to 1000 centipoise at 25"C where the organic group is selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, vinyl radicals, aryl radicals, cycloalkyl radicals and fluoroalkyl radicals of 3 to 8 carbon atoms such that polymer has a silanol content varying from 2 to 10% by weight; (c) from 0 to 200 parts by weight of a filler; (d) from 1 to 50 parts by weight of a hydride polymer of the formula,

where R2 is selected from the class consisting of hydrogen, alkyl radical of 1 to 8 carbon atoms; vinyl radicals and aryl radica Is and fluoroa Ikyl radicals of 3 to 8 carbon atoms and R3 is selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, aryl radical and fluoroalkyl radicals of 3 to 8 carbon atoms where the hydrogen polymer has a hydrogen content varying from 0.3 to 1.6% by weight andy varies such that the polymer has viscosity varying from 5 to 100 centipoise at 250C when there is also at least 1 mole of SiH per mole of silanol; and (e) from 1 to 250 parts per million of a solubilized platinum catalyst; (2) apply said mixture about electric system; and (3) allow said mixture to form an elastomeric silicone foam.

29. The process of Claim 27 wherein the electric system is part of a nuclear installation.

30. The process of Claim 28 were steps (1), (2), and (3) take place at room temperature.

31. A silicone composition capable of being foamed and having burn resistant properties substantially as hereinbefore described in any one of the foregoing Examples.

32. A process for producing a silicone composition capable of being foamed substantially as hereinbefore described in any one of the foregoing Examples.