GB1599209A - Silicone compositions containing colloidal silica - Google Patents

Description

(54) SILICONE COMPOSITIONS CONTAINING COLLOIDAL SILICA (71) We, GENERAL ELECTRIC COMPANY, a Corporation organized and existing under the laws of the State of New York, United States of America, of I River Road, Schenectady, 12305, State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a silicone composition for coating paper and textiles and more particularly the present invention relates to a silicone composition which is an SiH olefin platinum catalyzed composition for coating paper or textiles to increase their release properties and to make them water repellent respectively.

The use of silicone compositions in coating paper or textiles is well known. In the field of textiles it is desirable to coat such textiles so as to make them water repellent and also to increase the softness of the fabric. In another aspect, in paper finishing operations, it is desirable to coat paper so as to increase its release properties when it is used as a releasing cover paper for pressure sensitive adhesives. Silicone compositions for such uses are well known. The use of water dispersions and the use of solvent dispersions of a silicone composition for such purposes is well known. The silicone composition can comprise a silanol terminated diorganopolysiloxane polymer, an alkyl silicate as a cross-linking agent with or without the use of precipitated silica fillers and a metal salt of carboxylic acid as a catalyst.

Briefly, the alkyl silicate cross-linking agent along with the catalyst is mixed separately and is stored separately from the other parts of the composition and when it is desired to cure the composition, the two components are mixed and applied to paper to enhance its sizing properties and in some instances to enhance its release properties. In one aspect such compositions are undesirable because of the presence of an organic solvent which may cause problems in terms of pollution since the solvent has to be evaporated to cure the composition.

In the coating of textiles, the use of methyl hydrogen polysiloxanes are also well known. However, methyl hydrogen fluids for such purposes have the disadvantage that, upon being stored they may occasionally give off hydrogen gas resulting in flamability problems. In addition, methyl hydrogen polysiloxanes are not as useful in coating textiles to make them water repellent as could be desired, since the fluids tend to migrate into the pores of the textile before cure, such that the textile is not fully water repellent. Silicone compositions comprising the reaction product of an SiH olefin platinum catalyzed compositions are also well known for use as molding compounds. Recently such compositions have been utilized in the coating of paper. Such compositions have been formulated either as water emulsions or in terms of solventless systems, thus eliminating the problem of pollution associated with organic solvents. One such composition is for instance that disclosed in Moeller U.S. Patent 4,008,346.

Briefly, such a composition comprises preparing by emulsion polymerization a vinyl-containing polymer which, after it has been prepared, is present in the form of an emulsion. There is also added to the base emulsified polymer the appropriate amount of a hydrogen siloxane, cross-linking agent and a platinum catalyst. Usually the hydrogen siloxane is emulsified along with the platinum catalyst and stored as a separate component. When the catalyst component is mixed with the base polymer which is an emulsion, the resulting composition can then be coated on paper or textiles to enhance the release properties of the paper and to some extent impart water repellent properties to textiles. There may be also added to such compositions any of well known additives such as vinyl fluids, emulsifying agents, and bactericides, such well known additives being used to enhance the properties of the emulsified SiH olefin platinum catalyzed composition as long as the additive does not interfere with the reaction of the SiH polysiloxane with the olefinic containing polysiloxane or inhibit the reactivity of the platinum catalyst. As disclosed in the foregoing Moeller Patent, the base polymer is desirably prepared as an emulsion polymerized material, since it is very difficult to properly emulsify a vinyl-containing base polymer of high viscosity. A patent on SiH olefin platinum catalyzed compositions for coating materials is U.S. Patent 3.900,617 where the emulsion is prepared without emulsion polymerization through the use of emulsifying agents. The advantage of this Grenoble Patent over that of the Moeller Patent is that the emulsion utilizing traditional emulsifying agents is considerably more difficult to form. A disclosure of emulsion polymerization is also to be found in the Finlay, et al U.S. Patent 3,294,725, although the Patent does not deal directly with the production of emulsified vinyl containing polysiloxane for use in SiH olefin platinum catalyzed compositions. Further, in respect to the Grenoble Patent, when such a composition was applied to coat paper, while it was useful for sizing the paper, nevertheless before the composition cured, the silicone composition tended to migrate into the pores of the paper; thus, making such compositions not very acceptable as release coatings. In addition, the Grenoble composition, because of migration of the uncured composition, while it tended to impart some water repellency properties of textiles, nevertheless would be improved upon. The same problems appear to be case with the SiH olefin platinum catalyzed compositions of the Moeller Patent. While the Moeller composition is useful for coating paper so as to increase its release properties to pressure sensitive adhesives, nevertheless the composition fell short of imparting good water repellency properties to textiles and to imparting optimum release properties to paper when it was used to coat paper. Accordingly, to decrease the migration properties of the silicone composition on the coated substrate it was suggested prior to the present case to utilize a thickening agent in the composition such as carboxymethyl cellulose, hydroxyethyl cellulose, or polyvinyl alcohol to thicken the composition and prevent the migration of the silicone composition into the pores of the substrate increasing the desired properties to be imparted to the substrate. In addition, it should be noted that it was tried to include fumed and precipitated silica in the foregoing Moeller and Grenoble patented compositions. However, such fillers decrease the stability of the emulsion and created undue problems in preparing an emulsion of the composition since such fumed and precipitated silica tended to precipitate out from the emulsified composition.

There is provided by the present invention a silicone composition useful for coating paper and textiles comprising (A) 100 parts by weight of a base polysiloxane selected from polymers of the formula,

and of the formula,

and mixtures thereof where R is a monovalent hydrocarbon or halohydrocarbon radical free of unsaturation, R' is amonovalent olefinic hydrocarbon radical and R" is selected from the class consisting of monovalent hydrocarbon on halohydrocarbon radicals free of aliphatic unsaturation and monovalent olefinic hydrocarbon radicals, and x andy are positive integers such that the polymer has a vinyl content (as hereinafter defined) from 0.1 to 4% by weight and the viscosity of the polymer is from 50,000 to 500,000 centipoise at 250C (B) from 1 to 25 parts by weight of colloidal silica: (C) from 1 to 50 parts by weight of an organic hydrogen polysiloxane having the average unit formula, (3) (R2)a(ll)bSO(48b?!2 where R2 is a monovalent hydrocarbon radical free of aliphatic unsaturation; a is from 0 to 3, b is from 0.005 to 2.0 and the sum of a plus b is from 0.9 to 3, there being at least one silicon-bonded hydrogen atom per molecule; (D) from 1 to 500 parts per million of platinum catalyst; and (E) water. Such composition can be prepared in the form of a dispersion or in the form of a semi-emulsion by dispersing the ingredients and adding well known emulsifying agents to the composition so as to emulsify it. A more preferred manner of preparing the composition of the instant case is to prepare the vinyl-containing base polymer by emulsion polymerization which will be disclosed hereinbelow. Such a polymer to which the colloidal silica is added is stored separately. The hydrogen siloxane along with the platinum catalyst and emulsifying agents and water is prepared in the form of an emulsion and is stored separately. As is well known with such SiH olefin platinum catalyzed compositions, when it is desired to cure the composition, the two emulsions or dispersions are mixed together and the resultant mixture is applied to a substrate and cured at room temperature by evaporation of the water over a prolonged period of time or cured rapidly by heating the composition and the substrate to a temperature of above 1000C for a period of time from 10 seconds to 5 minutes, to completely cure the composition into a coating. Further advantageous ingredients may be utilized in the instant composition as it will be discussed below. The novel ingredient in the instant composition is colloidal silica, which has a pH in the range of 7.5 to 11.5 and which colloidal silica is dispersed into the solvent selected from the class consisting of water and an aliphatic alcohol, or in a mixture of water and an aliphatic alcohol, where the aliphatic alcohol has 1 to 8 carbon atoms. In addition, it is preferred that the colloidal silica have a particle size varying from 1 to 100 microns and have a surface area of 100 to 500 meters per gram. Colloidal silica is preferably added to the base vinyl-containing polymer after the silica has been emulsified in the form of a water concentrate of 30 to 70% by solids, and more preferably 4060% by weight of solids, and the colloidal silica preferably has a silanol content from 5 to 20% by weight. Examples of such colloidal silica are well known and are sold by many manufacturers in the market. Colloidal silica can be utilized with advantage in the instant compositions to prevent and slow down the migration of the uncured silicone compositions of the instant case into the coated substrate with the desired results.

Accordingly, by the use of the instant composition to coat paper and textiles, there are obtained enhanced release properties to pressure sensitive adhesives of papers coated with the above composition, and such compositions render textiles more water repellent than is possible with the emulsified systems of the Moeller Patent or of the Grenoble Patent. It should be pointed out that the present invention is not limited to the use of silicone compositions in the uncured state in the form of an emulsion. The composition can be utilized as dispersions of the silicone compositions in water. More preferably, however, the SiH olefin platinum catalyzed composition with the colloidal silica as will be discussed below are utilized to coat papers and textiles in the form of emulsions or semi-emulsions since this facilitates the handling of the composition for such coating procedures.

In formulae I and 2 above of the base polymer R can be any monovalent hydrocarbon radical free of any aliphatic unsaturation such as alkyl radicals of I to 8 carbon atoms, e.g. methyl, ethyl or propyl; cycloalkyl radicals such as hexyl or heptyl; mononuclear aryl radicals such as phenyl, or methylphenyl; and halogenated monovalent hydrocarbon radicals such as 3,3,3-trifluoropropyl. R' is selected from monovalent hydrocarbon radicals containing vinyl unsaturation or other aliphatic unsaturation, such as alkenyl radicals of 2 to 8 carbon atoms e.g.

vinyl, allyl, etc. Most preferably in the above formulas R' is vinyl. The radical R" on the other hand can be any of the radicals described above for Rand R'. In the more preferred embodiment R" is a monovalent hydrocarbon radical or halogenated monovalent hydrocarbon radical free of aliphatic unsaturation such as radicals given above for the R radical. Most preferably R is selected from alkyl radicals of from I to 8 carbon atoms and phenyl radicals, or 3,3,3-trifluoropropyl radicals. In the most preferred embodiment R is methyl. In the case of R" it is most preferably vinyl or a lower alkyl radical of 1 to 8 carbon atoms such as methyl. In the above formulae x andy are positive integers such that the above polymers of formulae ( I ) and (2) have a viscosity from 50,000 to 500,000 centipoise at 250C. Preferably the polymers of formulae (1) or (2) have a viscosity from 100.000 to 500,000 centipoise at 25 C.

In addition, in the above formulae x and v are such that the polymer has a vinyl content from 0.1 to 4% by weight. As used herein the expression "vinyl" means a group of the formula -CH=CH2. The polymers may contain other unsaturated aliphatic groups in addition, but must contain 0.1 to 4% by weight of vinyl groups. It is preferred that the vinyl content of the polymer is from 0.1 to 104 by weight.

Further in the most preferred coating composition of the instant case, it is preferred that the base polymer of formula (1) be utilized rather than that of formula (2), since it is more stable and more emulsifiable in a water system.

However, the invention of the instant case will apply with either polymer of formulae (1) or (2). The preparation of such polymers is well known in the art.

Briefly, for instance, the polymer of formula (l) can be prepared by equilibrating cyclic polysiloxanes and specifically octoorgano-cyclic tetrasiloxanes having the appropriate substituent groups, whether they be monovalent hydrocarbon radicals free of aliphatic unsaturation or whether they be vinyl radicals, in the appropriate quantities in the presence of a mild acid catalyst such as toluene sulfonic acid. Such equilibration is carried out at elevated temperatures above l00 C for a period of time varying from 1 to 8 hours until the reaction reaches completion when about 85% of the cyclic tetrasiloxanes have been converted into the linear polymer. The catalyst is then neutralized with an appropriate mild base and the cyclics are vented off to give the appropriate silanol terminated polymer formula 1. By utilizing the appropriate R' containing chain stoppers in the above equilibration reaction, the polymers of formula (2) can be formed. The cyclic tetrasiloxane reactants are obtained, as is well known in the art, by simply hydrolyzing the appropriate dichlorosilanes and then cracking the hydrolyzate with KOH or another strong base, and preferentially distilling overhead and obtaining in maximum yield the appropriate cyclic tetrasiloxane.

In the preferred embodiment of the instant case, such base polymers are obtained by emulsion polymerization, as disclosed in Moeller U.S. Patent 4,008,346 which was referred to previously. As set forth in that Patent, such emulsion polymerized compounds are obtained by homogenizing a mixture of compounds comnsing reacting a cyclictetrasiloxane of the formula (R2SiO)4 with a compound of the formula (RR'SiO)4 or a compound of the formula (R2SiO)4 with the compound of the formula (RR"SiO)4 with a compound of the formula,

where R, and R' and R" are as previously defined and z is from I to 20. Such compounds are first homogenized along with a benzene sulfonic compound of the formula.

where R3 is an alkyl group from 6 to 8 carbon atoms and sufficient water. The quantities of the cyclic tetrasiloxanes that are reacted are such that the desired concentrations of the R, R1 and R" groups appear in the base polymers. The concentration of the benzene sulfonic acid may be from 100 to 1.000 parts per million.

Generally, the cyclic tetrasiloxanes are homogenized with sufficient water to provide 10 to 60 , solids in the water dispersion. After these reactants and catalysts have been homogenized, the resulting composition is heated to a temperature from 40 to 100 C for a period of time from I to 5 hours. A shorter reaction time can be utilized, but the reaction may not reach completion by then and the longer reaction time serves no purpose. After a 5 hour period, it is desirable to cool the reaction mixture to room temperature for l to 8 hours, and more preferably from 2 to 5 hours. It is desired to have the composition cooled to room temperature for that period of time so as to stabilize the emulsified polysiloxane polymers of formulae (1) or (2) so as to stabilize the emulsion. It is possible that some of the polymer may precipitate out of the emulsion if too rapid a cooling period is utilized or is not utilized at all. It also should be noted that the composition can be cooled to below room temperature advantageously and in accordance with the present invention for the foregoing period of time through the use of refrigeration. After such cooling period, the benzene sulfonic acid is then neutralized with the appropriate amount of an alkanolamine. The result is a neutralized emulsion of the polysiloxanes of formulae (l) or (2). With respect to the benzene sulfonic acid, any of the benzene sulfonic acids falling within the scope of the above formula may be utilized in the instant case, but one that is most readily available and performs as the most efficient or the most preferred catalytic agent in the process in such emulsion polymerization has been found to be dodecyl benzene sulfonic acid. Another advantage of such an acid that is readily available. As far as the alkanolamine is concerned any type of alkanol amine within the scope of the formula (R40H)3N may be utilized where R4 is an alkylene radical of I to 8 carbon atoms. Such alkanolamine neutralizing agents are preferred since they tend to buffer the emulsified polysiloxane polymers and stabilize the emulsion. Other stronger basic agents may be utilized, such as sodium hydroxide or potassium hydroxide but such agents may tend to precipitate out some of the polysiloxane polymers of formulae (1) or (2) that have been formed. Also the salts that are formed from such neutralization procedures have the disadvantage that they may degrade the cured silicone composition that is formed. For more information and details as to the emulsion polymerization process by which the polymers of formulae (1) and (2) may be formed reference is made to the disclosure of the Moeller Patent. The novel feature of the present invention is the use of colloidal silica, and generally from 1 to 25 parts of colloidal silica per 100 parts by weight of the base polymers of formulae (1) and (2). Preferably, such colloidal silica is utilized at a concentration of 1 to 15 parts by weight, and has a pH in the range of 7.5 to 11.5. More preferably the pH is in the range from 8.5 to 10.5, in which pH range the silica is more stable. It should be noted that such a silica is also stable at acidic pH, such as at a pH below 5.

However, it is not desired to add an acidic colloidal silica to the base polymer unless the composition is going to be cured immediately, since such acidic colloidal silica would add on to the vinyl groups in the base polymer of formula (1) or (2).

Normally, the colloidal silica is packaged or mixed with the base polymer of formula (1) or (2) and is sold and stored as such prior to use. When it is desired to use the composition, the mixture of the emulsion of the base polymer of formula ( I) or (2) having the colloidal silica dispersed therein is mixed with the hydrogen polysiloxane cross linking agent and the composition is applied and cured.

Accordingly, it is highly desirable to use a basic colloidal silica with the base polymers of formulae (1) and (2) of the instant case. Accordingly, such a colloidal silica is dispersed in water or in a water-alcohol mixture in which it is also stable at a solids content of 30 to 70% solids, or more generally at a solids content from 40 to 600o solids, to the emulsion of the base polymer of formula (1) or (2). The two ingredients are mixed thoroughly and result in a stable semi-emulsion of the colloidal silica in the foregoing base polymer of formula (1) or (2). A platinum catalyst may then be added to the base compositions, and the composition stored as such or the platinum catalyst may be added to the hydrosiloxane mixture. The catalyst is most preferably added to the hydrosiloxane mixture in accordance with the accepted practices in the art. The alcohol that may be utilized in the alcoholwater mixture to contain the colloidal silica prior to its mixing with the emulsion of the base polymer of formula (l) or (2) is generally any aliphatic alcohol having 1 to 8 carbon atoms and is more preferably methanol, ethanol or propanol. Further, because of pollution problems, it may be desirable to utilize the colloidal silica dispersed in water. A general description of such colloidal silica is that it can have a particle size from 1 to 100 microns and a surface area of 100 to 500 square meters per gram. It is also preferable that such a colloidal silica have a silanol content of from I to 25%, by weight or more preferably a silanol content of from 5 to 20%.

With such a silanol content, the colloidal silica reacts with facility with the other reactants and the total silicone composition to produce a good coherent silicone coating. It should be noted that the colloidal silica may be also added to a water dispersion of the base polymers of formula (1) or (2) which is formed by simply homogenizing the base polymers by traditional procedures. In addition, the colloidal silica may be added to an emulsion of the compound of formula (1) or (2) which are formed by traditional procedures utilizing traditional emulsification agents, such as the Triton emulsifiers and emulsifying agents sold by Rohm & Haas.

Co., Triton being a trade mark for a grade of octylphenoxypolyethoxyethanol emulsifying agents or generally alkylphenoxypolyethoxyethanol emulsifying agents in which the alkyl radical is an aliphatic radical having from 5 to 15 carbon atoms.

Other emulsifying agents that may be utilized either to emulsify the base polymers of formula (1) or (2) or the hydrogen-polysiloxane that will be described below to prepare a stable emulsions by traditional procedures are as follows: T-Maz 80 sold by Mazer Chemical Company Glycosperse 20 sold by Glyco Chemical Company Nonionic E-8 sold by Hodag Chemical Company Nonionic E-20 sold by Hodag Chemical Company Nonionic E-4 sold by Hodag Chemical Company Igepal CO-850 sold by GAF Corporation Surfonic N-40 sold by Jefferson Chemical Company Poly-Terg J-200 sold by Olin Corporation Hyonic PE-50 sold by Nopco Chemical Company T-DET-N-4 sold by Thompson Hayward Company Renex 648 sold by ICI America Company The names of the above surfactants are tradenames of the company selling the surfactants and their composition is readily avilable.

The colloidal silica as described above is the critical ingredient in the invention of the instant case which results in low migration of the silicone compositions described above when utilized to coat paper or textiles and thus results in a more coherent and more effective silicone compositions when applied to coat paper or applied to textiles to make them water repellent. An ingredient that may be mixed with vinyl base polymer is from I to 500 parts per million of the total composition of a platinum catalyst. Platinum catalyst that may be utilized in the present composition may be platinum deposited on a solid carrier such as platinum on charcoal or platinum/gamma alumina, or it may be solubilized platinum complex.

The solubilized ~ platinum complex are preferred in the present composition since they are the more reactive. Preferred platinum catalysts are those platinum compound catalysts which are soluble in the present reaction mixture. The platinum compound can be selected from those having the formula (PtCl2 . Olefin)2 and H(PtCI3. olefin) as described in U.S. Patent 3,159,601 Ashby. The olefin shown in the previous two formulae can be almost any type of olefin but it is preferably an alkenyl radical having from 2 to 8 carbon atoms. Specific olefins utilizable in the above formulas are vinyl and allyl. A further platinum containing material usable in the composition of the present invention is a platinum chloride cyclopropane complex (PtCI2. C3H)2 described in U.S. Patent 3,159,662 Ashby. Still further the platinum containing material can be a complex formed from chloroplatinic acid with up to 2 moles per gram of platinum of a member selected fr6m the class consisting of alcohols, ethers, aldehydes and mixtures of the above as described in U.S. Patent 3,320,972 Lamoreaux. All the patents and patent applications mentioned in the present specification are incorporated into the present application by reference. Another preferred platinum catalyst is then disclosed in U.S. Patent 3,775,452 Karstedt. Any of these platinum catalysts may be utilized at the above concentration in the invention of the instant case, although as stated previously the preferred catalysts are the solubilized platinum complexes.

Accordingly, with such a platinum catalyst there is formed the one component of the two component system of the instant case. The platinum catalyst along with the colloidal silica is dispersed in the emulsion of the polymer of formula (1) or (2) so that there is formed a total stable semi-emulsion having a solids content of 50c to 70% by weight of solids. The second component is preferably prepared either as a water dispersion or an emulsion of the hydrogen polysiloxane cross-linking agent of formula (3). Such hydrogen polysiloxane can be dispersed in water or can be emulsified in water using the traditional emulsifying procedures with the traditional emulsifying agents as was discussed above with respect to emulsifying basic polymers of formulae (1) and (2). In a more preferred embodiment such organohydrogen polysiloxane is composed of R22HSiOo 5 units and SiO2 units with a ratio of the monofunctional siloxy units to the tetrafunctional siloxy units from l to 2.7, and the hydride content of the resin is from 0.5 to 2% by weight. The radical R2 can be as stated any monovalent hydrocarbon radical free of aliphatic unsaturation, such as for instance alkyl radicals of I to 8 carbon atoms, or cycloalkyl radicals such as hexyl or heptyl, mononuclear aryl radicals such as phenyl, methylphenyl, ethylphenyl and halogenated monovalent hydrocarbon radicals free of aliphatic unsaturation such as 3,3,3-trifluoropropyl. Such resins are well known in the art and are simple to prepare by simply hydrolyzing the appropriate chlorosilanes and tetrachlorosilanes or ethyl orthosilicate in water or in a mixture of water with a water-immiscible organic solvent such as benzene, toluene and xylene. For instance the appropriate quantities of ethyl orthosilicate and R2HSiCI may be hydrolyzed in a mixture of water and xylene at room temperature to result in the appropriate silicone resin. The resin, which is soluble in xylene, may be washed with water and refluxed at the refluxing temperature of xylene to remove all acid along with the water from the solution of the resin in the water-immiscible organic solvent. The resin may then be obtained in pure form by simply distilling off of the water-immiscible organic solvent. Preferably such resin when utilized in the instant invention, is emulsified with water and the standard emulsifying agents such as the Triton emulsifying agents of Rohm & Haas Co. may be used to obtain a silicone emulsion of the hydrogen polysiloxane cross-linking agent. Another type of hydrogen polysiloxane which may be utilized in the instant process and which is not a resin is a hydrogen-containing polysiloxane linear polymer. The hydride content of the polysiloxane can be from 0.5 to 2% by weight.

Preferably the organic hydrogen polysiloxane has a viscosity of from 100 to 10,000 centipoise at 250C. Such polymers may be obtained by the hydrolysis of the appropriate chlorosilanes and specifically hydrogendimethylchlorosilane along with diorganodichlorosilanes to obtain the appropriate hydrolyzate. If higher viscosity material is desired, that is, above 1000 centipoise at 250C, the hydrolyzate is then simply cracked with a strong alkali metal catalyst such as KOH to preferentially distill overhead above the desired cyclic tetrasiloxanes. The cyclic tetrasiloxanes may then be equilibrated to produce the hydrogen containing p above. It should be noted that fumed or precipitated silica are highly undesirable to be utilized in place of or in addition to colloidal silica disclosed above in the compositions of the instant case since they will not properly disperse or emulsify in water and will precipitate out from the composition thus not imparting to it the desired properties The total components when mixed together both the first component and second component as explained above, will result in a composition which can be diluted with water to have a solids content from 5 to 70 l,.

It should be noted that if the instant composition is to be utilized as a dispersion, the ingredients have to be mixed together or the ingredients of the different components must be dispersed immediately prior to use, and the two components must be mixed together immediately prior to use and applied as such in a quick fashion, otherwise the ingredients would settle out from the water dispersion. Accordingly, it is highly desirable to utilize a semi-emulsion of the two components of the instant case. Accordingly, in accordance with the instant invention, there is prepared an emulsion of the polysiloxane base polymer in which there is dispersed the colloidal silica, thus maintaining the emulsion. The component is stored with or without the platinum catalyst, and more preferably with the platinum catalyst also dispersed in the emulsion. The second component the hydrogen polysiloxane, is also prepared by emulsifying it with traditional emulsifying agents. The second component, the hydrogen polysiloxane crosslinking agent, is utilized or must be emulsified with the traditional emulsifying agents. Although such hydrogen polysiloxane need not be emulsified to form the second component, it is highly desirable that it be since it will mix more easily into the emulsion of the base polymer. Accordingly, there are prepared the two preferred emulsions, which are stored separately and have shelf lives of 6 months or more. When it is desired to cure and apply a coating of the composition, the emulsions of the two components are simply mixed in the appropriate ratio and the composition is applied to coat paper or textiles and allowed to cure. Curing is accomplished by simply allowing the composition to dry at room temperature, which may take a period of time of from 1 hour to 24 hours or, in a more preferred procedure, heating the composition at elevated temperatures above 1000C for a period of time of from 10 seconds to 1 minue to drive off the water and cure the composition. It should also be noted that when the base polymer of formula (1) or (2) is desired to have a viscosity of 100,000 centipoise at 250C or above, it is preferred to prepare the polymer or emulsion polymerization, since it is very difficult to form emulsions of such high viscosity polymers using traditional methods. With respect to the concentration of the ingredients, per 100 parts of the base polymer of formula (1) or (2) or a mixture thereof, there is utilized generally from 1 to 25 parts by weight of colloidal silica, and more preferably I to 15 parts by weight of colloidal silica, and from I to 50 parts by weight of an organic hydrogen polysiloxane cross-linking agent, and more preferably from 1 to 25 parts by weight of the organic hydrogenpolysiloxane cross-linking agent. Then there is utilized a platinum catalyst at a concentration of 1 to 500 parts per million by weight of the total composition, and preferably at a concentration of I to 100 parts per million per weight of the total composition. A level of platinum catalyst that is above 500 parts per million serves no useful purpose, and unduly increases the cost of the composition, and on the other hand the use of platinum at less than I part per million by weight of the total composition may not initiate the reaction quickly enough. The amount of water that is utilized in the total composition will vary depending on the desired solids content for application to the coating of paper or textiles. Preferably such arnount of water is such as to provide a total silicon solids in the composition of anywhere from 5% solids to 70,' by weight of the composition.

If such composition is emulsified by traditional emulsification procedures it may contain from 0.5 to 20 parts by weight of an emulsifying agent based on 100 parts of the base polymer of formulas (I) and (2). To apply the composition, the two components are mixed and the coating is applied over the textile or the paper it is desired to coat therewith. The thickness that is applied will vary depending on the procedures, and the specifications of the coating operation. As stated previously, the composition can then be allowed to cure at room temperature by the evaporation of water in a period of time from l to 24 hours or by the curing of the composition at elevated temperatures of above 100or and allowing the composition to cure in a period of time from 10 seconds to 1-5 minutes. Such curing procedures are well known in the art. The examples below are for the purpose of illustrating the present invention. The are not given for any purpose in defining the scope or setting forth limitations on the scope of the instant inventlon. All percentages are by weight.

EXAMPLE I There was prepared a mixture in water comprising 44.75% by weight of octa- methyl cyclic tetrasiloxane 0.25% by weight of tetramethyftetravinylletracyclic siloxane, 0.0315% of a platinum catalyst which was Lamoreaux's platinum catalyst.

The mixture also contained 53.939% weight of water, and 0.620% by weight of dodecylbenzene sulfonic acid. The resulting composition, which was thoroughly mixed, was heated at 750C for 3 hours, and was cooled to room temperature over 6 hours. The resulting emulsified polymer was neutralized with 0.31% by weight of triethanolamine, to which was also added 0.1% by weight of formalin as a bactericide. The resulting polymer that was emulsion polymerized in the above composition was adjusted to 40% solids and had a viscosity of 150,000 centipoise at 25"C and was silanol-terminated, the vinyl content of the polymer was 0.03% by weight. This composition shall be known as composition A. There was prepared a composition B which was formed by mixing 20% by weight of a silicone resin composed of H(CH3)2SiO ,S units and SiO2 units where there were 2 moles of the monofunctional siloxy units to the tetrafunctional siloxy units and the resin had a hydride content of 0.9% by weight. To this there was added 20% by weight of a linear vinyl dimethyl-terminated dimethylpolysiloxane polymer of a viscosity of 4,000 centipoise at 250C, 1.4% by weight of Triton X-305 and 3.2% by weight of Triton X-114, Triton being the trade name of Rohm & Haas Co. for their octylphenoxypolyethoxyethanol emulsifying agents. To this there was added 4.6% by weight of water and the resulting ingredients were homogenized to prepare an emulsion. To these ingredients there was further added 50.66% by weight of water, by weight of the total composition. It should be noted that both in Composition A and Composition B that the percentages by weight given are percentages by weight of the total composition of the particular emulsion.

To the resulting diluted emulsified composition of Composition B there was added 0.04 weight per cent of acetic acid to stabilize the emulsion and 0.10% by weight of formalin as a bactericide. Formalin being a trade name of formaldehyde.

This composition which is referred to as Composition B was also adjusted to 40% by weight of solids. It had a pH of 3.5 to 5.5. This Composition B is the catalyst composition. In the test described below 20 parts by weight of Composition A was catalyzed in I part by weight of Composition B. The parts in this example are by weight. There were carried out tests in accordance with the present invention and are set forth herein in which the above Composition A and the mixture of Composition A and B in identical amounts was compared to an identical composition having no colloidal silica. The compositions of the instant case were prepared by mixing 80 parts of Composition A with 20 parts of coloidal silica.

There was one test with Composition A and colloidal silica and Composition B and one test with Composition A and colloidal silica without Composition B.

In the results below, Composition C refers to Compositions A and B mixed together to form a mixture to 80 parts of which there was added 20 parts of colloidal silica. Composition A in the table of results refers to the testing of Composition A without colloidal silica. In the table of results Composition D in the testing of 80 parts of Composition A with 20 parts of colloidal silica. Thus, the compositions of the instant case were tested both in the cross-linked and uncrosslinked state. Two sets of tests were run in each case. The compositions were tested according to the Silicone Products Department, General Electric Co. Tests for determining ease of paper release which test procedure is as follows: Equipment and Material 1. Circulating air oven at 1 500C with recirculating vent fully open.

2. 3/4" Scotch Transparent Tape #610.

3. GE adhesion tester with Stansi scales of 1000 gm. capacity. Speed 12 in./min., or Instron tester (Keil tester).

4. Hooks, paper clamps.

5. Laboratory paper coater.

6. 1-3/4" tape roller, 2200 gms. (=4.85#).

7. 40 Ib. Supercalendered Kraft (SCK) paper.

8. #0 equalizer rod.

9. Conditioning room at 250C and 50% R.h.

Procedure 1. Prepare composition to be tested.

SM-2l 16 40 gms.

2. Cut 8"x 10" pieces of SCK.

3. Coat duplicate pieces of SCK with bath.

4. Cure composition for 30 seconds at 1500C in sheets.

5. Permit the cured sheet to cool to room temperature, then apply two 3/4no88 pieces of Scotch Tape to each sheet. Apply tapes parallel to direction of the coating on one sheet and perpendicular to the direction of the coating on second sheet.

6. Check remainder of the coated sheet qualitatively for cure by rubbing in one direction with index finger using moderate pressure. Check coating-If film smears easily, reject batch. Balling andlor rub-off is permissable.

7. Age taped sheets from Step #5 one fourth hour at room conditions.

8. Make two passes with the 4.85# rubber roller over tapes. Do not exert pressure when rolling. Use only the weight of the roller as pressure.

9. Manually pull scotch tape free from coated surface. Carefully bend tapes in a loop and allow adhesive surfaces to touch. Leave 1" at each terminal end of tape free for attaching to clamps in tester. Do not press tape together.

10. Pull tapes by means of the adhesion tester. The free ends are to be mounted in tester using clamps. When being pulled, the adhesive surfaces will be separated and the force required to separate surface will be recorded.

11. Likewise, use an 8" pieces of scotch tape from the roll and measure adhesion as in Step #10.

12. Calculate % adhesion.

Average Test Tape Adhesion x 100=% Migration Adhesion Average Control Tape Adhesion Another test that was utilized to determine the identical compositions with and without colloidal silica is Federal Test Method 5526 for determining water repellency, which is as follows: Federal Test Method 5526 Water Resistance of Cloth with Hydrophobic Finish-spray Method.

1. Scope 1.1 This method determines the hydrophobic effectiveness of water-repellent finishes applied to cloth by measuring the amount of water absorbed.

2. Test Specimen 2.1 The specimen shall be a square of cloth 8 inches by 8 inches.

3. Apparatus 3.1 Six-inch glass laboratory funnel held by a laboratory ring support.

3.2 Spray nozzle of 1-7/16 inch outside diameter having a convex face with a 1 1/14 inch radius and connected to the funnel with a piece of 3/8 inch rubber tubing.

3.2. I The nozzle shall be provided with 19 holes, 0.035 inch in diameter (No.

65 drill), having 1 hole in the centre, 6 evenly spaced holes on a 25/64 inch diameter circle, and 12 evenly spaced holes on a 27/32 inch diameter circle concentric with the outside circumference of the nozzle.

3.2. 2 The distance from the top of the funnel to the bottom of the nozzle shall be 7-1/2 inches.

3.3 Metal embroidery hoops 6 to 7 inches in diameter for mounting the specimen.

3.4 Block of wood for supporting the mounted specimen so that the plane of the specimen makes an angle of 45" with the horizontal.

3.5 The distance from the bottom of the nozzle to the center of the hoop mounted specimen shall be 6 inches.

4. Procedure 4.1 Unless otherwise specified in the material specification, the specimen shall be securely mounted, finished side up, in the embroidery hoops with sufficient tension to insure a uniformly smooth surface.

4.2 Unless otherwise specified in the material specification, the direction of the flow of water down the specimen shall coincide with the warp-wise direction of the specimen as placed on the stand.

4.3 The mounted specimen shall be placed on the block with the center of the specimen directly beneath the center of the nozzle and the plane of the surface of the specimen at a 450 angle with the horizontal.

4.4 A 250 ml. volume of distilled water at a temperature of 26.7 +1.0 C (80 +1.8 F) shall be poured quickly into the funnel and allowed to spray onto the specimen which should take approximately 25 to 30 seconds.

4.5 Upon completion of the spraying period, the hoop shall be grasped at one edge and the opposite edge tapped downward against a solid object, the wet side of the specimen being face down during tapping. The hoop shall then be turned 1800, grasped at the opposite edge, and similarly tapped at the point previously held.

4.6 After tapping, the finished side of the cloth shall be compared with the standard Figure 5526B and the wetted and/or spotted pattern on the specimen assigned a rating corresponding to the nearest standard rating.

4.6. 1 No attempt shall be made to assign to the cloth an intermediate rating, 4.6. 2 In rating light porous cloth, passage of water through the open construction of the cloth shall be disregarded.

The colloidal silica that was used was Nalcoag 1140 which is a colloidal silica having a solids content of 40% by weight, a pH of 9.7 and an average particle size of 15 microns and specific gravity at 680 Fahrenheit of 1.296. Such a silica is sold by the Nalcoag Chemical Company, Chicago, 111.

Results of the above tests are as follows: In the compositions that were submitted to the above tests, Compositions A and B were mixed together in the 20 to 1 ratio and to 80 parts of such a mixture there was added 20 parts of colloidal silica. The results of the testing of such compositions using Federal Test Method 5526 are set forth in Table I below: TABLE I Results of Test Method 5526 Compositions 1 2 Compositions A & B 70 70 Composition C 100 100 Even without catalysts, results of rating significantly improved.

Composition A 50 50 Composition D 70 70 The Compositions A & B and Composition C were also tested in the paper release test specified above, the combination of Compositions A & B gave a release value of 37 to 46 grams per inch square as an average while Composition C gave a release value of 8 to 12 grams per inch of square as an average value. The above results indicate that compositions of the instant case utilizing colloidal silica are vastly superior to the Sill olefin platinum catalyzed compositions not containing colloidal silica in them.

WHAT WE CLAIM IS: 1. A silicone composition which comprises: (a) 100 parts by weight of a base polysiloxane having the formula:

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (18)

**WARNING** start of CLMS field may overlap end of DESC **. 4.3 The mounted specimen shall be placed on the block with the center of the specimen directly beneath the center of the nozzle and the plane of the surface of the specimen at a 450 angle with the horizontal. 4.4 A 250 ml. volume of distilled water at a temperature of 26.7 +1.0 C (80 +1.8 F) shall be poured quickly into the funnel and allowed to spray onto the specimen which should take approximately 25 to 30 seconds. 4.5 Upon completion of the spraying period, the hoop shall be grasped at one edge and the opposite edge tapped downward against a solid object, the wet side of the specimen being face down during tapping. The hoop shall then be turned 1800, grasped at the opposite edge, and similarly tapped at the point previously held. 4.6 After tapping, the finished side of the cloth shall be compared with the standard Figure 5526B and the wetted and/or spotted pattern on the specimen assigned a rating corresponding to the nearest standard rating. 4.6. 1 No attempt shall be made to assign to the cloth an intermediate rating, 4.6. 2 In rating light porous cloth, passage of water through the open construction of the cloth shall be disregarded. The colloidal silica that was used was Nalcoag 1140 which is a colloidal silica having a solids content of 40% by weight, a pH of 9.7 and an average particle size of 15 microns and specific gravity at 680 Fahrenheit of 1.296. Such a silica is sold by the Nalcoag Chemical Company, Chicago, 111. Results of the above tests are as follows: In the compositions that were submitted to the above tests, Compositions A and B were mixed together in the 20 to 1 ratio and to 80 parts of such a mixture there was added 20 parts of colloidal silica. The results of the testing of such compositions using Federal Test Method 5526 are set forth in Table I below: TABLE I Results of Test Method 5526 Compositions 1 2 Compositions A & B 70 70 Composition C 100 100 Even without catalysts, results of rating significantly improved. Composition A 50 50 Composition D 70 70 The Compositions A & B and Composition C were also tested in the paper release test specified above, the combination of Compositions A & B gave a release value of 37 to 46 grams per inch square as an average while Composition C gave a release value of 8 to 12 grams per inch of square as an average value. The above results indicate that compositions of the instant case utilizing colloidal silica are vastly superior to the Sill olefin platinum catalyzed compositions not containing colloidal silica in them. WHAT WE CLAIM IS:

1. A silicone composition which comprises: (a) 100 parts by weight of a base polysiloxane having the formula:

wherein R is a monovalent hydrocarbon or halohydrocarbon radical free of unsaturation, R' is a monovalent olefinic hydrocarbon radical, R" is a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic unsaturation or a monovalent olefinic hydrocarbon radical, and x and y are positive integers, the polymer having a vinyl content (as hereinbefore defined) of from 0.1 to 4% by weight and a viscosity from 50,000 to 500,000 centipoise at 250C; (b) from I to 25 parts by weight of colloidal silica; (c) from 1 to 50 parts by weight of an organic hydrogen polysiloxane having the average unit formula: (R2)a(H)hSiOt4~a~bll2 wherein R2 is a monovalent hydrocarbon radical free of aliphatic unsaturation; a is from 0 to 3, b is from 0.005 to 2.0 and the sum of a plus b is from 0.9 to 3, there being at least one silicon-bonded hydrogen atom per molecule; (d) from 1 to 500 parts per million of a platinum catalyst by weight of the total composition; and (e) water.

2. A composition as claimed in Claim 1, wherein the composition is an emulsion wherein the base polysiloxane is prepared by a process comprising (i) heating a homogenized mixture comprising: I. A compound of the formula: (R2SiO)4; with a compound of the formula, (RR'SiO)4; or II. A compound of the formula: (R2SiO)4 with a compound of the formula, (RRSiO)4 and with a compound of the formula

where z is from 1 to 20; along with said compounds there being present III. a benzene sulfonic compound of the formula:

wherein R3 is an alkyl group of from 6 to 8 carbon atoms; and IV. water; (ii) adding an alkanol amine to the mixture to neutralize the benzene sulfonic acid and to form a neutralized emulsion of said polysiloxane.

3. A composition as claimed in Claim 2, wherein the homogenized mixture is heated at a temperature from 40 to 100oC and subsequently cooled.

4. A composition as claimed in Claim 2 or 3, wherein the benzene sulfonic acid is dodecyl benzene sulfonic acid.

5. A composition as claimed in any of Claims 2 to 4, wherein the alkanolamine has the formula, (R40H)3N wherein R4 is an alkylene radical of 1 to 8 carbon atoms.

6. A composition as claimed in any preceding claim, wherein the colloidal silica is utilized at a concentration of 1 to 15 parts by weight and has a pH in the range of 7.5 to 11.5.

7. A composition as claimed in any preceding claim, wherein the colloidal silica is dispersed in water and/or an aliphatic alcohol having 1 to 8 carbon atoms.

8. A composition as claimed in any preceding claim, wherein colloidal silica has a particle size from 1 to 100 microns and a surface area of 100 to 500 square meters per gram.

9. A composition as claimed in any preceding claim, wherein the colloidal silica is utilized at a concentration of 30 to 70% solids in water and has silanol content of 1 to 25% by weight.

10. A composition as claimed in any preceding claim, wherein organic hydrogen polysiloxane is composed of R22llSiO05 units and SiO2 units where the ratio of monofunctional siloxy units to the tetrafunctional siloxy units is from I to 2.7 and the hydride content is from 0.5 to 2% by weight.

11. A composition as claimed in any preceding claim, which comprises from I to 20 parts by weight of a vinyl-containing polydiorganosiloxane polymer having a viscosity from 500 to 10,000 centipoise at 250C, which polymer is chain-stopped with vinyldiorganosiloxy units and the organo substituent groups being alkyl having 1 to 8 carbon atoms or phenyl.

12. A composition as claimed in any preceding claim, which additionally contains from 0.5 to 20 parts by weight of an alkylphenoxypolyethoxy ethanol as emulsifying agent.

13. A composition as claimed in any preceding claim, wherein the platinum catalyst is a platinum complex formed from platinum and a vinyl-containing polysiloxane.

14. A composition as claimed in any preceding claim, wherein R is methyl and R' is vinyl.

15. A process for forming a cured silicone composition which comprises forming a composition according to any preceding claim by (1) mixing (A) 100 parts by weight of the base polysiloxane (B) from 1 to 25 parts by weight of the colloidal silica; (C) from I to 50 parts by weight of the organic hydrogen polysiloxane, (D) from I to 500 parts per million by weight of the total composition of the platinum catalyst; and (E) water; and (2) allowing the water to evaporate and the composition to cure.

16. A process for coating textiles to make them water repellent which comprises (1) applying to said textiles a composition as claimed in any of Claims 1 to 14, and (2) allowing the water to evaporate and the composition to cure.

17. A process for coating paper to improve its release properties comprising (I) applying to said paper a composition as claimed in any of Claims 1 to 14, and (2) allowing the water to evaporate and the composition to cure.

18. A composition as claimed in Claim 1 and substantially as hereinbefore described.