KR840001758B1 - Silicone foam compositions with burn resistant properties - Google Patents

Abstract

Foamable burn resistant silicone compsn. comprises (a) 100pts.wt. of base vinyl-contg. polymer of formula(I) (R,R'=1-8C alkyl, aryl, vinyl, 3-8C fluoroalkyl; the polymer contains 0.002-3 wt.% vinyl; X is such that viscosity rises from 10 to 105CP at 250oC), (b) 1-10 pts. wt. of a silanol-contg. silicone of viscosity 10-103 CP at 25oC, the org. gp. being as for R and R' and such that silanol content is 2-10%, (c)0-200 pts. wt of a filler, (d) 1-50 pts.wt. of hydride polymer of formula(II) (R2=H, 1-8C alkyl, aryl or 3-8 C fluoroalkyl; R3=1-8C alkyl, aryl, 3-8 C fluoroalkyl; the H content is 0.3-1.6 wt. %; Z is such that viscosity is 5-100CP at 250 deg.C where there is also at least 1 mole of SiH per mole of silanol), and (e) 1-250ppm.of a solubilised pt catalyst.

Description

Flame Retardant Silicone Foam Composition

FIELD OF THE INVENTION The present invention relates to silicone compositions, and more particularly to silicone compositions which can be made into flame retardant insulating foams by foaming at room or elevated temperatures. The silicone composition generally consists of a silicone polymer and various additives which are cured into silicone elastomers at room or elevated temperatures.

In the case of SiHolefin platinum catalyzed compositions, such compositions are generally configured as vinyl containing polysiloxanes, hydrogen containing polysiloxanes and platinum catalysts. Such silicone compositions can be foamed at room temperature to produce flame retardant materials for electrical devices, particularly those for nuclear reactors.

After contacting the components with each other, the resulting composition is cured with silicone elastomer at room temperature. By adding an inhibitor to the composition, it is possible to prevent the composition from curing at room temperature over time, but it quickly cures at elevated temperatures. The composition is cured with a silicone elastomer. Other compositions that are cured with elastomers include, for example, compositions that are cured with organic peroxides, commonly referred to as thermoset silicone rubber compositions, or by-products that are cured by condensation reactions. However, Si-H olefin platinum catalyzed compositions are preferred over these compositions for several reasons of use. first

The purpose of the US Pat. No. 3,425,967 is to develop a high strength silicone foam, which can be used to produce molded articles that are flame retardant but hard enough to wear without use.

The silicone foams described in Modic US Pat. No. 3,425,967 have abrasion resistance and can be used as panel materials, such as flame retardant partitions, which are well suited for this purpose. Tensile strength of the silicone foam produced by the patent of Modic and

There are two disadvantages to using an external blowing agent as described in the patent, firstly adding a chemical foaming agent as an additive component in the composition, which adds additional costs such as the cost of the additive or the cost of mixing it into the composition. The second disadvantage is that the composition must be heated at elevated temperature in order to proceed with the reaction of the system. If a silicone foam cannot be formed within itself in a nuclear reactor or other building or construct, using it becomes very difficult. Such a silicone foam composition is thus foamed at room temperature so that the composition is sent through a conduit to a nuclear reactor and in some cases to a construct, where necessary the silicone foam itself is produced within the conduit. Recently, attempts to produce silicone foams at room temperature for insulation of electrical devices against fire have been disclosed in Smith, US Pat. No. 3,923,705. This patent describes a process for producing silicone foams by reacting siltanol-containing polysiloxanes with SiH materials in the presence of a platinum catalyst, optionally at room temperature or optionally at elevated temperatures. While this patent has several advantages, one disadvantage of this method is that it does not produce suitable foams with all forms of platinum catalyst.

The compositions are US patents for preparing suitable silicone foams.

Therefore, it is highly desirable if more than 85% by weight of vinyl polysiloxane can be added in order to increase the strength of the composition and to make the silicone foam composition prepared every batch more reliable and better reproducible in physical properties.

To solve this problem, Frank J. US Patent Application No. 886,186, entitled Docket 60SI-78, filed March 13, 1978 by Frank J. Modic. The application describes the preparation of silicone foams consisting of vinyl-containing polysiloxanes, hydrogen-containing polysiloxanes, platinum catalysts with other components and small amounts of water (water acts as blowing agent).

The composition overcomes the problems of the composition in the prior art, whereas the water is separated from the other components when the composition is left for a certain time.

According to the invention, (a) 100 parts by weight of the basic vinyl-containing polymer of formula (1), (b) so that the content of silanol in the polymer is 2 to 10% by weight, preferably 5 to 10% by weight, Silanol-containing organic silicone compounds 1 to 10 having an organic group selected from alkyl radicals having 1 to 8 carbon atoms, vinyl radicals, aryl radicals and fluoroalkyl radicals having 3 to 8 carbon atoms, and having a viscosity of 1 to 100 centipoise at 25 ° C. A flame retardant silicone foam composition is provided, consisting of parts by weight, (c) 0 to 200 parts by weight of filler (d) 1 to 50 parts by weight of hydrogen siloxane of formula (2) and (e) 1 to 250 ppm of dissolved platinum catalyst.

Wherein R and R ¹ are selected from alkyl radicals having 1 to 8 carbon atoms, aryl radicals, vinyl radicals and fluoroalkyl radicals having 3 to 8 carbon atoms so as to contain 0.0002 to 3% by weight of vinyl in the polymer; R ² is selected from hydrogen, alkyl radicals having 1 to 8 carbon atoms, aryl radicals and fluoroalkyl radicals having 3 to 8 carbon atoms; R ³ is a hydrogen polymer from 0.3 to

The limitation for the platinum catalyst is that it is not just solid platinum on charcoal but must be a dissolved platinum complex that is readily dispersed in the constituents. Solid platinum catalysts also work to some extent, but suitable foams cannot be produced without using one of the dissolved platinum complexes. Any of the dissolved platinum complexes can be used to produce suitable foams that are reproducible.

The composition of the present invention can be synthesized from 10 to 100 parts of a basic vinyl-containing polymer of a resin consisting of one functional unit and four functional units or optionally a resin consisting of one functional unit and four functional and bifunctional silicone units. In the composition, fibrous fillers as well as conventional reinforcing or extending fillers may be added.

The composition according to the present invention preferably contains 100 parts by weight of the basic vinyl-containing polymer of general formula (I). In formula (I), R and R ¹ may be selected from hydrocarbons and halogenated hydrocarbons, provided that the vinyl substituent is present in 0.0002 to 3% by weight and the vinyl substituent is 100 to 1,000,000 centipoise at 25 ° C. It should exist as much as possible.

Accordingly, such hydrocarbon groups and halogenated hydrocarbon groups include alkyl radicals such as methyl, ethyl, propyl, and the like; Cycloalkyl radicals such as cyclohexyl, cycloheptyl, cyclooctyl and the like; It may be selected from known substituents for mononuclear aryl radicals such as phenyl, methylphenyl, ethylphenyl and the like, alkenyl radicals such as vinyl, preferably vinyl and diorganopolysiloxane polymers. R and R ¹ radicals are halogenated hydrocarbons such as alkalicals having 1 to 8 carbon atoms, aryl radicals such as phenyl, vinyl radicals and fluoroalkyl radicals having 3 to 8 carbon atoms (e.g., 3,3,3-trifluoropropyl). It is preferable to select from radicals.

R and R ¹ are most preferably selected from methyl radicals, phenyl radicals, vinyl radicals and 3,3,3-trifluoropropyl radicals when the polymer has such vinyl substituents.

The preferred viscosity range of the polymer is of course further limited by the preferred vinyl concentration of 0.0002 to 0.1% by weight of the polymer vinyl concentration with a viscosity of 2,500 to 250,000 centipoise at 25 ° C. The present invention may be progressed using polymers with a wide range of vinyl concentrations, but the reaction rate is not too slow and the reaction can proceed at a sufficiently suitable rate according to the inventive process and the polymers for producing cured silicone elastomer foams The vinyl concentration can be further restricted during the reaction to achieve a suitable crosslink within. For the preferred viscosity range, it is desirable that the viscosity of the vinyl mixed composition before the silicone foam is formed is not too high so that it is not difficult to handle and pour the composition. Therefore, the vinyl-containing polymer is preferably a low viscosity material when preparing the composition in this case. Therefore, as described above

Wherein R ¹ is selected from methyl, phenyl and 3,3,3-trifluoropropyl and V is a variable that allows the polymer to have a viscosity in the range of 100 to 1,000,000 centipoise at 25 ° C.

The most preferred form of the base vinyl containing polymer according to the invention is that the vinyl group is only at the siloxy end units as described in the general formula (3) above. However, it is also possible to use polymers in which the vinyl units are only in the siloxy units on the polymer chain, so that silicone foams can be produced in which the vinyl units are present only in the siloxane chains and the vinyl end units are not present in the polymer. Such basic vinyl-containing polymers, however, cannot produce foams with physical properties as good as silicone foams prepared as vinyl-containing polymers containing vinyl-terminated siloxy units.

In another more preferred aspect of the present invention, as the basic vinyl-containing polymer, a polymer in which vinyl units are bonded to the siloxy units on the polymer chain as well as the terminal position of the polymer chain can be used. Although such polymers also produce suitable silicone elastomeric foams, such foams are not as desirable and do not have good physical properties as vinyl-based base polymers of the general formula (3) are most preferred for use in the inventive process. . Such vinyl-containing polymers are well known in the art and can be prepared according to methods known in the art.

In the context of non-fluorinated polymers, such vinyl containing polymers are cyclic by hydrolyzing suitable diorgano dichlorosilanes in water and then, for fluorinated polymers, hydrolysates at elevated temperatures with alkali metal hydroxides, preferably KOH Tetrasiloxane or cyclic tree siloxane is optionally distilled from above, followed by taking cyclic tetrasiloxane, and maintaining equilibrium in the presence of a small amount of potassium hydroxide and a suitable bond stopper at elevated temperature, i.e. can do. In preparing the polymer of the general formula (3), it is necessary to use an appropriate amount of divinyltetraorganodisiloxane bond stopper, such as a divinyl tetramethyldisiloxane bond stopper.

The resulting mixture is heated above 150 ° C. and equilibrated until approximately 85% by weight of the cyclictetrasiloxane is converted to the linear polymer of the desired viscosity. “The mixture is cooled at equilibrium, the alkali metal hydroxide is neutralized with a suitable weak acid such as phosphoric acid and the unreacted cyclic compound is discharged to separate it from the desired vinyl-containing polymer. Suitable vinyl-containing polymers are suitable not only from polymers of general formula (3), but also suitable vinyl-containing cyclic tet.

Thus, any polysiloxane having a silanol group that can be easily condensed can be used in this case and reacts with the hydrogen polysiloxane in the composition,

Wherein R ⁵ and R ⁶ are selected from monovalent hydrocarbon radicals such as vinyl radicals, aryl radicals and fluoroalkyl radicals, hydroxy groups and mixtures thereof; t is the default of

The compound of the general formula (4) is a straight chain compound and is preferable as the silanol compound within the scope of the present invention. However, as described above, silanol-containing polysiloxanes can be equally readily used in the present compositions.

The R ⁵ and R ⁶ radicals may be selected from halogenated monovalent hydrocarbon radicals as defined in the R and R ¹ radicals of the vinyl-containing polymer of formula (1). This also means that in the definition of the organic group in the silanol-containing silicone compound, the organic group may be the same as the vinyl-containing polysiloxane of the general formula (1) since the polysiloxane of the general formula (4) also falls within the range.

The polysiloxane is present at a concentration of 1 to 10 parts by weight per 100 parts by weight of the basic vinyl-containing polymer of formula (1). If it is 1 part by weight or less, it is difficult to discharge a sufficient amount of gas that can generate a good foam, it is not useful to use more than 10 parts, which is a waste of silanol material. In addition, 10 parts by weight or more of silanol-containing polysiloxane may generate too much hydrogen to form large pores in the system. More preferably, 1 to 5 parts by weight of silanol-containing polysiloxane as described above is used. The third necessary component in the composition according to the present invention is 1 to 50 parts by weight of hydrogenated polysiloxane of the general formula (2). In the general formula (2), R ² is selected from hydrogen, alkyl radicals having 1 to 8 carbon atoms, aryl radicals and fluoroalkyl radicals having 3 to 8 carbon atoms, and R ³ is selected from alkyl radicals and aryl radicals having up to 8 carbon atoms. Selected and contains 0.3 to 1.6% by weight of hydrogenated polymer hydrogen,

The hydrogen content of such polymers should therefore be measured in terms of the number of moles of water per mole of hydrogen polysiloxane crosslinker. It is also important to note that viscosity is very important and y is a variable that is adjusted so that the polymer viscosity varies in the range of 5-100 centipoise, preferably 5-40 centipoise. Although high viscosity and high molecular weight hydrogen containing polysiloxanes may be used, it should be noted that such polymers are difficult to obtain and difficult to use with suitable hydrogen content for use in the present invention. For this reason, the reaction of the present invention proceeds according to the present specification, and it is necessary for the hydrogenated polymer of the general formula (3) to contain hydrogen on the siloxane chain. The hydrogenated polymer may contain hydrogen atoms on the terminal siloxy atoms, but must contain hydrogen atoms on the polymer chain in order to proceed with the reaction according to the invention. In the absence of hydrogen atoms in the polymer chain of the hydrogenated polymer, suitable silicone foams cannot be obtained. Thus, the hydrogenated polymers of the present invention having only hydrogen atoms on terminal siloxy atoms do not act to produce silicone foams in the compositions of the present invention.

By way of limitation, R ² can be selected from hydrocarbon radicals and halogenated radicals generally associated with polysiloxane polymers, other than hydrogen and preferably aliphatic unsaturated radicals. Thus R ² radicals are alkyl radicals such as methyl, ethyl, propyl; Cycloalkyl radicals such as cyclohexyl, cycloheptyl and the like; Aryl radicals of a single nucleus such as phenyl, methylphenyl, ethylphenyl and the like; It is preferably selected from halogenated hydrocarbon radicals such as fluoroalkyl radicals, 3,3,3-trifluoropropyl and the like. More preferably, the R ² radical is selected from 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, most preferably R ² is methyl, phenyl and Selected from 3,3,3-trifluoropropyl radicals. The radical R ³ is selected from alkyl and aryl radicals of up to 8 carbon atoms. It is preferable that the vinyl-containing polymer does not contain any hydrogen substituent, and in the hydrogen polysiloxane polymer of the general formula (2), it is preferable that there is no vinyl or aliphatic unsaturated substituent. It is preferable to use 1 to 50 parts by weight of the hydrogenated polysiloxane crosslinking agent of the general formula (2) per 100 parts of the basic vinyl-containing polymer of the general formula (1). The production of unfluorinated hydrogen substituted polysiloxane polymers is much simpler than the production of vinyl containing polymers as described above. Low viscosity hydrogen substituted polysiloxane polymers are basically prepared by hydrolyzing suitable hydrogen substituted dichlorosilanes with diorgano chlorosilanes with an appropriate amount of chain-stopper, with or without hydrogen substitution.

In the production of hydrogenated polymers as well as in the production of vinyl-containing polymers of the general formula (1), disiloxane, trisiloxane or low molecular weight linear polymers are suitable as substituted polymerization terminators. Monomer silanes containing suitable substituents such as hydrogen dimethyl chlorosilane, trimethylchloro silane, 3,3,3-trifluoropropyl dimethyl chlorosilane are used as polymerization terminators in the hydrolysis reaction in the production of hydrogenated polysiloxane polymers. do. Thus such polymerization inhibitors, which are chlorosilanes containing appropriate substituents, can be used to prepare low viscosity and low molecular weight hydrogenated polysiloxane polymer crosslinkers of the general formula (2).

Low molecular weight polymers may also be prepared by equilibrating an appropriate cyclic tetrasiloxane with an appropriately weak acid catalyst, for example acid-active clays such as Filtrol, above.

In the equilibration reaction carried out at an elevated temperature using an acid catalyst, the reaction is carried out at a temperature of preferably 90 ° C. or higher, more preferably 100 ° C. or higher to equilibrate the cyclic tetrasiloxane, and about 85 of the cyclic tetrasiloxane. The% is converted to a linear polymer where it is filtered to remove the acid catalyst and the cyclic compound is discharged to produce the desired linear polymer.

In the case of fluorinated polymers, somewhat different formulations are used to prepare fluorinated polymers. In the case of the vinyl-containing base polymer of formula (1), the appropriate fluorinated cyclictetra siloxane is equilibrated with a polymerization terminator in the presence of certain basic catalysts such as cesium hydroxide and potassium silanolate at about 90 ° C. or somewhat higher temperatures. And convert 50-60% to a linear polymer having a viscosity at 25 ° C. up to at least 1,000,000 centipoise and then

For the purposes of the present invention, where it is desired to produce fluorine-substituted hydrogenated polysiloxane polymers within the formula (2) range, suitable fluorine-substituted chlorosilanes can be prepared by direct hydrolysis. Finally, in the process of the present invention, generally from 1 to 250 ppm platinum catalyst, preferably from 1 to 200 ppm platinum catalyst is used. In the process of the present invention, it is more preferable to use stabilized platinum complexes because the stabilized platinum complexes can be dispersed much more easily in the component and shorten the reaction time.

Several kinds of platinum compounds are known for SiH-olefin addition reactions.

Particularly preferred platinum catalysts where optical clarity is required are platinum compound catalysts which are soluble in the present reaction mixture. The platinum compound may be selected from compounds of the structural formulas (PtCl ₂ olefins) and H (PtCl ₃ olefins) as described in US Pat. No. 3,159,601 to Ashby. As the olefins present in the two structural formulas, olefins of all types can be used, but alkenyl having 2 to 8 carbon atoms, cycloalkenyl having 5 to 7 carbon atoms or styrene is preferable. Specific olefins that can be used in the above formula include various isomers such as ethylene, propylene or butylene, cyclopentene, cyclohexene, cycloheptene and the like.

The platinum containing material usable in the compositions according to the invention is also the platinum chloride cyclopropane complex (PtCl ₂ · C ₃ H ₆ ) ₂ described in US Pat. No. 3,159,662 (Ashby). In addition, the platinum-containing material may be a complex compound produced by up to 2 moles of alcohol, ether, aldehydes and mixtures thereof per second gram of platinum and a second chloroplatinic acid as described in US Pat. No. 3,220,972 (Lamoreaux).

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

Preferred platinum compounds for use as platinum catalysts as well as flame retardant additives are platinum divinyltetramethyldisiloxane compounds as described in US Pat. No. 3,775,452 (Karstedt).

Typically, this type of platinum complex is a second chloride bag containing 4 moles of hydrated water.

As described above, the compositions according to the present invention are not sensitive to certain types of platinum catalysts as in the case of the compositions of the prior art, so that various kinds of platinum catalysts may be used in the process of the present invention for producing silicone foams. Can be. However, preferred platinum catalysts within the scope of the present invention are the Lamoreaux catalyst or Karstedt platinum catalyst described in the patent.

One of the preferred catalysts within the scope of the present invention is the Karsted platinum catalyst, which reacts dichloroplatinic acid with vinyl-containing cyclotetrasiloxane or vinyl-containing low molecular weight polysiloxane in the presence of an alcohol and a weak base such as sodium bicarbonate. It is prepared so that the platinum complex contains almost no chlorine. Such catalysts can be advantageously used in the compositions of the present invention because of their reactivity. Platinum catalysts, such as the Karstedt Platinum Complex Catalysts within the scope of the present invention, are highly reactive, allowing the foams to be foamed at a high rate so that low density materials are produced at a higher rate than with other forms of platinum catalysts. Has the advantage of releasing at a high speed.

Platinum complex compounds produced from dichloroplatinic acid and vinyl-containing siloxane materials may also be used as catalysts in the preparation of the present compositions, whether or not chlorine is present. However, platinum complex catalysts obtained by the reaction of vinyl-containing siloxane and platinum chlorinated dibasic and having a substantially reduced chlorine content are catalysts with different properties, which are more advantageous in the production of silicone foams according to the invention. Used.

In addition there are other forms of dissolved platinum catalysts usable in the present invention. Unlike the compositions of the Dowco-Ning, Smith patent, the compositions of the present invention do not exhibit sensitive reactions to certain types of dissolved platinum catalysts. Solid platinum catalysts such as platinum / charcoal are not preferred in the present invention because they do not produce good foams, such as dissolved platinum catalysts. In spite of this clue, however, dissolved catalysts can be used in the present invention in any form. More preferred is the Karstedt platinum catalyst, which is a very reactive catalyst that generates good bubbles. All of these components can be used to make silicone foams. In general, it is characteristic to store the vinyl polymer separately from hydrogen polysiloxane. Platinum catalysts can be used with vinyl or with silanol compounds and vinyl containing polysiloxanes. When the hydride is mixed with silanol polysiloxane and vinyl-containing polysiloxane in the presence of a platinum catalyst, the resulting composition releases hydrogen to produce a silicone elastic foam. Inhibitors can be used in the composition to form a one-component reaction system that does not react at room temperature for months, but at elevated temperatures, ie, at 100 or 150 ° C. or more in minutes to produce good silicone foam. Thus vinyl-containing organopolysiloxanes such as methyl vinyl cyclotetrasiloxane can be used as inhibitors in the composition. Also triallyl isocyanurate uriate and dialkyl maleate may also be used.

Examples of the use of maleate are found in Richard's patent application (Richard P. Eckberg, Docket 60 SI-202 Entitled "Solventless Paper Release Compositions").

The inhibitor may be used in a concentration range of 100 ppm to 10,000 ppm with respect to the total composition, but the range is merely a preferred concentration range, and any desired concentration may be used depending on the inhibitor activity required. If too much inhibitor compound is contained, it may be difficult to adversely affect the physical properties of the composition or to initiate the reaction even at elevated temperatures. In general, however, inhibitor compounds may be used within this range.

Inhibitor compounds are not used when it is desirable to mix the composition and to produce the silicone elastomeric foam in minutes or seconds using factory production equipment. When silicone foams are produced in-house in electrical conductor-containing conduits in nuclear reactors or other buildings, it is desirable to produce silicone elastic foams by mixing the two components together at room temperature without the use of such inhibitor compounds.

The silicone foam can be prepared by simply mixing the components and mixing all the components well to produce a one-component system that can prevent the reaction of the components until a reaction is required, and then simply heating the generated one-component system to an elevated temperature. It is also preferable to form a one-component system. It should also be noted that the silanol-containing polysiloxane may be silane, not polysiloxane. Thus, in the present composition, the silane-containing silicone compound required to form the hydrogen-containing polysiloxane may be a silanol-containing silane having a required silanol content of up to 33% by weight of the silanol, thereby producing a silicone foam. It can act as a distributor of silanol in the composition at a concentration of 1 to 10 parts, preferably 1 to 5 parts per 100 parts of the base vinyl-containing polymer in the composition reacted with hydrogen polysiloxane to release hydrogen gas. However, silanol-containing polysiloxanes are capable of bubbling hydrogen gas.

It contains no hydrogen and has up to two hydroxy groups per molecule, and other groups and silicone groups are saturated monovalent halogenated hydrocarbon radicals such as alkyl radicals, vinyl radicals, aryl radicals and cycloalkyl radicals of 1 to 8 carbon atoms. Any phosphorus silanol-containing silane can be used in the present composition.

The composition is a good composition for the production of silicone elastomeric foam.

However, it is necessary to prepare such compositions with strength. The silicone foam of the base composition is an excellent elastomeric type, but does not have the strength to withstand wear loss or handling such as for ceilings or instrument panels. Since the silicone foams according to the invention must have flame resistance and toughness, the silicone foams of the invention require such wear and toughness properties. Thus, one way to increase the toughness of such silicone elastomeric foams is by incorporating filler into the composition. Therefore, 0 to 200 parts by weight of the filler may be mixed.

Extending fillers are preferred because reinforcing fillers, such as fumed silica and precipitated silica, are unduly mixed at any concentration into the composition because the viscosity of the composition is greatly increased and difficult to handle or use. However, fumed silica or precipitated silica has advantages in increasing physical properties, namely, tear and tensile strength of the silicone elastic foam prepared from the composition.

Thus, a more preferred aspect of the present invention is the use of 10 to 100 parts of filler for 100 parts of base vinyl-containing polymer.

The concentrations of the components mentioned in the present invention are all based on 100 parts of the basic vinyl-containing polymer. Thus, in a preferred embodiment, 10 to 100 parts of a filler selected from reinforcing fillers and extender fillers, preferably only extender fillers, may be used. Quartz powders are preferred as extenders for use in the compositions of the present invention that do not significantly increase the viscosity of the uncured composition. Quartz powder has the secondary advantage of somewhat increasing the flame resistance of cured silicone foams made from the composition. Other bulking fillers that may be used in the composition include titanium dioxide, lithopone, zinc oxide, zirconium silicate, silica aerogels, iron oxide, diatomaceous earth, potassium carbonate, glass fibers, magnesium oxide, chromium oxide, zirconium oxide, aluminum oxide, alpha quartz , Calcined clay, carbon, graphite, and the like.

If reinforcing fillers such as homedrisilica and precipitated silica are used, such fillers as well as bulking fillers may be treated with cyclic polysiloxane or silazane to keep the viscosity increase in the composition as low as possible. Methods for treating silica filler with cyclic polysiloxanes are described in US Pat. No. 2,938,009 to Lucas, which is incorporated herein by reference. However, this method is only one method of treating reinforcing fillers and other methods using other reagents may also be used in the art.

Other methods of treating reinforcing fillers include Brown, U.S. Patent No. 3,024,126, Smith, U.S. Pat.

SiO(여기에서, R⁷은 비닐라디칼 및 1단위/4단위 비율이 0.5 : 1 내지 1 : 1이고 또 실리콘원자의 약 2.5 내지 10몰%가 실리콘 결합 비닐그룹을 함유하는 1가 탄화수소라디칼 중에서 선택된다) 단위 및 SiO₂단위를 갖는 오르가노폴리실옥산 10 내지 100중량부를 조성물에 혼합시킬 수 있다. 상기 조성의 실리콘 수지는 1작용 및 4작용 단위로 이루어지며 실리콘 수지의 요구는 비닐함유 중합체와 양립하고 조성물 내에 분산되도록, 또한 계로 경화되도록 비닐 그룹을 갖는 것이다. R⁷이 탄소수 8까지의 알킬라디칼, 탄소수 8까지의 아릴라디칼, 비닐라디칼, 탄소수 3 내지 8의 플루오로 알킬라디칼 중에서 선택된 1가 탄화수소라디칼인 경우가 바람직하며, R⁷이 탄소수 1 내지 8의 알킬라디칼, 페닐라디칼 및 비닐라디칼 중에서 선택되는 것이 가장 바람직하며, 단 수지는 앞서 지적한 바와 같이 목적하는 비닐 치환기를 가져야 한다. 이와 같은 수지의 제조방법은 본 기술분야에서 공지되어 있다. 일반적으로, 제법은 상응하는 1작용성 트리메틸실란과 테트라클로로실란을 취하여 실란을 수-불혼화성 용매의 존재하에서 물에 가해주는 단계로 구성된다. 생성된 혼합물을 가수분해시켜, 톨루엔 또는 크실렌과 같은 수 불혼화성 유기용매 중에서 분리되거나 응집되는 실리콘 수지를 제조한 다음 가수분해 혼합물로부터 분리하고 물로 반복해서 세척하여 산을 정제한다. 이어 용매 중에 생성된 수지를 비닐 중합체에 가하여 혼합하고 간단히 용매를 증발시켜 조성물 중의 수지의 혼합물을 수득한다. 따라서 이 첨가제를 사용하므로써 어떠한 섬유질 또는 실리카 충진제 및 충진제의 보강문제를 갖지 않는 실리콘 발포 조성물의 제조가 가능Flame retardant fillers may be mixed in the composition only to increase the strength of the compositions of the present invention or to increase the flame resistance of the composition. The only problem with using silica fillers is their difficulty in pouring or mixing, when mixed in large amounts in the silicone composition due to the tendency to increase the non-cure viscosity of the composition. One way to solve this problem is to treat the filler with the silanes and polysiloxanes described above. Another method is to use fibrous fillers in the composition. One example of a fibrous filler that can be used in the compositions of the present invention is a blend of 10 to 100 parts by weight of inorganic fibrous material, such as potassium titanate, described in US Pat. No. 3,452,967 per 100 parts of basic vinyl-containing polymer. The most preferred of the fibrous fillers which increases the toughness of the composition but does not reduce the flame resistance or the flame retardancy is of course potassium titanate. Instead of these fillers, the use of silicone resins as fillers in the composition can also increase the toughness and tensile strength of the composition without excessively increasing the viscosity of the uncured composition and reducing the flame retardancy of the composition. Therefore, general formula (1)

SiO, wherein R ⁷ is selected from vinyl radicals and monovalent hydrocarbon radicals in which the ratio of 1 unit / 4 unit is 0.5: 1 to 1: 1 and about 2.5 to 10 mol% of silicon atoms contain silicon-bonded vinyl groups 10 to 100 parts by weight of an organopolysiloxane having a unit and a SiO ₂ unit can be mixed into the composition. Silicone resins of this composition consist of monofunctional and tetrafunctional units and the demand for silicone resins is to have vinyl groups to be compatible with the vinyl-containing polymer, to be dispersed in the composition, and to cure in a system. R ⁷ is and the case of alkyl radicals, aryl radicals, vinyl radicals and monovalent hydrocarbon radical selected from alkyl radicals fluoroalkyl having 3 to 8 carbon atoms of up to 8 carbon atoms of up to 8 carbon atoms Preferably, R ⁷ is an alkyl group having 1 to 8 carbon atoms Most preferably selected from radicals, phenylradicals and vinylradicals, provided that the resin has the desired vinyl substituent as indicated above. Methods for preparing such resins are known in the art. In general, the process consists of taking the corresponding monofunctional trimethylsilane and tetrachlorosilane and adding the silane to water in the presence of a water-immiscible solvent. The resulting mixture is hydrolyzed to produce a silicone resin that separates or aggregates in a water immiscible organic solvent such as toluene or xylene, then is separated from the hydrolysis mixture and washed repeatedly with water to purify the acid. The resin produced in the solvent is then added to the vinyl polymer, mixed and simply evaporated to obtain a mixture of the resin in the composition. The use of this additive therefore makes it possible to produce silicone foam compositions which do not have any fibrous or silica filler and filler reinforcement problems.

Addition of 10 parts by weight or less of resin per 100 parts of the basic vinyl-containing polymer did not show a significant result, and addition of 100 parts by weight or more did not show a significant improvement over the addition of a smaller amount. In addition, the mixing of the composition becomes very difficult when there is more resin than the amount of the base polymer.

Incidentally, other forms of resin consisting of one functional unit, two functional units and four functional units may be mixed in the composition. This type of resin, which also has a bifunctional unit in the first type of silicone resin consisting of only mono- and tetra-functional siloxy units, is another type of resin used in the compositions of the present invention. The advantage of using a second resin containing this bifunctional siloxy unit is that this type of resin gives more elasticity to the composition, and also a greater amount of vinyl in the resin to be incorporated into the base vinyl containing polymer. There is no advantage other than mixing. Thus, per 100 parts of the basic vinyl-containing polymer (R ⁷ ) ₃ SiO _0.5 units, and 10 to 100 parts by weight of the silicone resin polysiloxane polymer composed of R ⁷ SiO units and SiO ₂ units can be mixed, wherein R ⁷ is The ratio of 1 functional unit is about 0.5: 1 to 1: 1 and R ⁷ SiO unit is ^{7 7 7}

At least one mole of SiH per mole of silanol must also be present to produce the desired foam, with 2 to 5 mole percent SiH per mole of silanol of the final composition being preferred. While silanol refers to the silanol content in the silanol-containing silicone compound, SiH means the SiH concentration in the hydrogenated polysiloxane of the general formula (2). If there are 1 mole or less of SiH compound per mole of silanol group in the final mixture, sufficient hydrogen gas is not liberated to produce a good foam. If more than the desired amount, a suitable foam can be obtained. However, at this time, the amount of water released is too high, and uncured or unused hydride is present in the final silicone foam composition, thereby deteriorating physical properties such as flame retardancy in the cured silicone foam composition. It is therefore highly desirable to contain at least 1 mole of SiH in hydrogenated polysiloxane per mole of silanol group in the silanol-containing silicone compound as described above.

Additional components may be added to increase the flame resistance or flame resistance of the silicone foam. For example, 1 to 10 parts of carbon black and more preferably carbon black having a low residual sulfur content may be added per 100 parts of the basic vinyl-containing polymer of the general formula (1). Carbon black having a low sulfur content gives the composition of the present invention the best flame resistance. More preferably, 0.5 to 2 parts of carbon black having a low residual sulfur content may be used per 100 parts of the base vinyl-containing polymer. The addition of 2 parts or more of carbon black adds flame resistance, but not so much. Therefore, the preferred range of carbon black used in the composition of the present invention to impart flame resistance to the composition is 0.5 to 2 parts. 0.2 parts of carbon black, which has a low sulfur content, provides flame resistance to the composition.

Flame retardancy of the silicone foam composition according to the present invention does not interfere with the basic reaction for producing the silicone foam according to the present invention and is known flame retardant as long as it does not inhibit or harm the action of the platinum catalyst used in the olefin platinum catalyst reaction in the present invention. It can be further improved by adding an additive to the composition. This composition is typically prepared in a two-package form in which the hydrogenated polysiloxane is separated separately and does not contain a platinum catalyst. The vinyl silicone material and silanol silicone material are packaged with or without the platinum catalyst and the hydrogenated polysiloxane is packaged separately without the platinum catalyst. Mixing the two packages reacts at room temperature in the absence of an inhibitor to produce a silicone elastic foam.

By using an inhibitor, the components may be mixed and the production of the silicone foam may be delayed for a period of time depending on the inhibitor, but when the composition is heated at elevated temperatures, it will cure within minutes or seconds to form the silicone elastic foam. Therefore, it is possible to make a one-component system by using an inhibitor.

The following examples are intended to illustrate the invention and are not intended to limit the scope of the invention. All parts used in the examples are parts by weight.

Example 1

A mixture of vinyl terminated dimethylpolysiloxane 72:28 mixture 49.4 is prepared having a viscosity of 3,500 gs at 25 ° C. for the 72% component and 80,000 gs for the 28% component. The low viscosity component contains approximately 0.0015% vinyl while the high viscosity component contains approximately 0.0005% vinyl.

Example 2

A mixture of 46.8 parts of a mixture of vinyl-containing polysiloxanes as in Example 1 was prepared and contained 6.6 parts of 5 micron quartz, 0.6 parts of carbon black, 7.3% of platinum 12.5 ppm silanol as Karscat catalyst and had a viscosity at 25 ° C. 2 parts of the linear silanol-containing polysiloxane and 0.09 parts of methylvinyl tetramer of Example 1, which are 26 centipoises, were added thereto, and the hydropolysiloxane having a viscosity of 18 centipoise at 25 ° C. and a hydrogen content of 1.5% by weight. Part 3.7 is added. A flame retardant foam having a specific gravity of 0.38 is also obtained. The percentage of hydroxylated siloxane is approximately 4% of hydroxylated and vinyl siloxane.

Example 3

It consists of 75% by weight of vinyl chain interrupted polydimethylsiloxane having a viscosity of 80,000 cps, trimethylsiloxane, methylvinylsiloxane and SiO ₂ units, with a ratio of 0.8 trimethylsiloxane units per SiO ₂ and 7.0 moles of silicon atoms. A composition containing 25% by weight of an organosiloxane copolymer with methylvinylsiloxane being present so that% is present as methylvinyl siloxane units.

The mixture was catalyzed with 30 ppm of platinum in the form of Karstedt catalyst to yield 3.37 parts of silanol-containing polysiloxane in Example 1 and trimethyl chain-terminated poly with a viscosity of 18 centipoises at 25 ° C. with 1.5% hydrogen. 1.5 parts of methylhydrogen siloxane are added. A very tough foam with a specific gravity of 0.35 is produced.

Example 4

To 33.5 parts of the polysiloxane composition described in Example 3 was added 16.5 parts of quartz filler and 20 ppm of catalyst in the form of Karstedt catalyst to the weight of polysiloxane. The specific gravity of this composition is 1.28. When 0.25 parts of water was added followed by 3.3 parts of hydrogen polysiloxane in Examples 1 and 2 and vigorous stirring, foaming proceeded to give an elastic foam having a very high toughness of 0.31.

1% of TAIC, ie trialkyl isocyanurate, is added as a cure inhibitor at room temperature before adding polymethyl hydrogensiloxane to the composition described in Example 3. When polymethyl hydrogen siloxane is added, the reaction at room temperature cannot be observed and the system remains a viscous fluid. The system is cured and foamed by heating at 150 ° C. for 15 minutes to produce an elastic foam having a specific gravity of 0.41.

Claims (1)

100 parts by weight of the basic vinyl-containing polysiloxane polymer of the general formula (1); The organic group is selected from alkyl radicals of 1 to 8 carbon atoms, vinyl radicals, aryl radicals and fluoroalkyl radicals of 3 to 8 carbon atoms so that the silanol content in the polymer is 2 to 10% by weight, and the viscosity is 1 to 8 at 25 ° C. 1 to 10 parts by weight of a silanol-containing organosilicon compound which is 100 centipoise; Filler 0 to 200 parts by weight; 1 to 50 parts by weight of the hydrogenated polymer of the general formula (2); And 1 to 250 ppm of a platinum catalyst.

Wherein R and R ¹ are selected from 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 0.0002 to 3% by weight of vinyl, X is 25 Is a variable that causes the polymer viscosity to increase to 100 to 1,000,000 centipoise at ° C., R ² is selected from hydrogen, alkyl radicals of 1 to 8 carbon atoms, aryl radicals and fluoroalkyl radicals of 3 to 8 carbon atoms, and R ³ is hydrogen The polymer is selected from alkyl radicals of 1 to 8 carbon atoms, aryl radicals and fluoroalkyl radicals of 3 to 8 carbon atoms so that it contains 0.3 to 1.6% by weight of hydrogen, and Z also contains at least 1 mole of SiH per mole of silanol Where the polymer has a viscosity of 5 to 100 centipoise at 25 ° C.