| PATENT ASSIGNEE'S COUNTRY | Belgium |
| UPDATE | 11.98 |
| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 10.11.98 |
| PATENT TITLE |
Adhesion method employing organosiloxane compositions |
| PATENT ABSTRACT |
A moisture curable composition comprises a mixture and/or a reaction product of a polymeric material having not less than two groups bonded to silicon which are hydroxyl or hydrolyzable groups, an alkoxysilane curative, an adhesion promoter and catalyst material for catalyzing the condensation reaction between the polymeric material and the alkoxysilane curative. The adhesion promoter comprises a silicone-organic copolymer consisting of units (I) according to the general formula R.sub.a SiO.sub.(4-a)/2 and units (ii) according to the general formula R.sub.b R'SiO.sub.(3-b)/2 where R represents a monovalent hydrocarbon group and R' represents an oxyalkylene chain R.sup.6 (C.sub.2 H.sub.4 O).sub.x (C.sub.3 H.sub.6 O).sub.y Z in which R.sup.6 represents a hydrocarbon linkage to a silicon atom, Z represents H or a carboxylic acid residue. Also disclosed is a method of forming an elastomeric mass between surfaces which is adherent to at least two such surfaces which method comprises introducing between the surfaces said moisture curable composition. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | 02.04.97 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT REFERENCES CITED | This data is not available for free |
| PATENT CLAIMS |
That which is claimed is: 1. A method of forming an elastomeric mass between surfaces which is adherent to at least two such surfaces which method comprises introducing between the surfaces a mass of a moisture curable composition which comprises a product obtained by mixing a polymeric material having not less than two groups bonded to silicon which are independently selected from the group consisting of hydroxyl and other hydrolysable groups, an alkoxysilane curative, a finely divided filler and catalyst material for catalysing a condensation reaction between the polymeric material and the alkoxysilane curative, wherein the composition further includes an adhesion promoter which comprises a silicone-organic copolymer consisting of units (i) according to the general formula R.sub.a SiO.sub.(4-a)/2 and units (ii) according to the general formula R.sub.b R'SiO.sub.(3-b)/2 where each R is independently selected from the group consisting of monovalent hydrocarbon groups having up to 20 carbon atoms, each a is independently selected and has a value from 0 to 3, each b is independently selected and has a value from 0 to 2 and each R' is independently selected and represents an oxyalkylene chain R.sup.6 (C.sub.2 H.sub.4 O).sub.x (C.sub.3 H.sub.6 O).sub.y Z where R.sup.6 represents a hydrocarbon linkage to a silicon atom, each Z is independently selected and is selected from the group consisting of H and carboxylic acid residues, each x is the independently selected and has a value from 0 to 20 and each y is independently selected and has a value from 0 to 20 and x+y has a value from 3 to 40. 2. A method according to claim 1 wherein the groups R' of the units (ii) provide no more than 40% by weight of the silicone organic copolymer. 3. A method according to claim 1 wherein the polymeric material is an at least substantially linear polydiorganosiloxane having terminal groups selected from the group consisting of SiMe.sub.2 OH and SiMe.sub.2 R"'Si(OR.sup.5).sub.3 wherein R"' is a divalent hydrocarbon group which may be interrupted by one or more siloxane spacers having up to 6 silicon atoms and R.sup.5 is selected from the group consisting of alkyl and oxyalkyl groups in which the alkyl groups have up to 6 carbon atoms. 4. A method according to claim 1 wherein the alkoxysilane is methyl trimethoxysilane. 5. A method according to claim 1 wherein the finely divided filler is silica. 6. A method for promoting adherence of an elastomeric mass to two or more surfaces, which elastomeric mass is formed from a moisture curable composition which comprises a product obtained by mixing a polymeric material having not less than two groups bonded to silicon which are independently selected from the group consisting of hydroxyl and other hydrolysable groups, an alkoxysilane curative, a finely divided filler and catalyst material for catalysing a condensation reaction between the polymeric material and the alkoxysilane curative, wherein the method further comprises including in the composition adhesion promoter which comprises a silicone-organic copolymer consisting of units (i) according to the general formula R.sub.a SiO.sub.(4-a)/2 and units (ii) according to the general formula R.sub.b R'SiO.sub.(3-b)/2 where each R is independently selected from the group consisting of monovalent hydrocarbon groups having up to 20 carbon atoms, each a is independently selected and has a value from 0 to 3, each b is independently selected and has a value from 0 to 2 and each R' is independently selected and represents an oxyalkylene chain R.sup.6 (C.sub.2 H.sub.4 O).sub.x (C.sub.3 H.sub.6 O).sub.y Z where R.sup.6 represents a hydrocarbon linkage to a silicon atom, each Z is independently selected and is selected from the group consisting of H and carboxylic acid residues, each x is the independently selected and has a value from 0 to 20 and each y is independently selected and has a value from 0 to 20 and x+y has a value from 3 to 40. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
This invention is concerned with moisture curable organosiloxane compositions which are curable to elastomers and also relates to the use of such compositions as sealing materials. Organosiloxane compositions which cure to elastomeric solids are well known. Typically, such compositions are obtained by mixing a polydiorganosiloxane having reactive terminal groups, generally silanol groups, with a silane cross-linking agent for the polydiorganosiloxane, for example an alkoxy silane, an acetoxy silane, an oxime silane or an amino silane. These materials are frequently curable upon exposure to atmospheric moisture at room temperature. One important application of the above-described curable compositions is their use as sealants in which there is formed an elastomeric mass between surfaces which is adherent to at least two such surfaces. It is frequently desirable that the composition cures quickly enough to provide a sound seal within several hours but not so quickly that the surface cannot be tooled to desired configuration shortly after application. One important requirement of such materials is the ability to adhere well to a variety of substrates and it is a normal practice to include so called adhesion promoters in such compositions. The use of plastics in various industries, particularly the construction industry, is increasing. This is especially true for plastics such as polyvinylchloride (PVC), used for window frames, polymethylmethacrylate (PMMA), used for bathtub and bathroom accessories, and polycarbonate (PC) such as Lexan, used as transparent sheeting material or for the manufacture of safety glass laminates and insulating glass units. Although many calcium carbonate filled neutral sealants are available that develop sufficient adhesion to such plastics, silica filled materials typically show poorer plastic adhesion than their calcium carbonate filled counterparts. It is known to include in alkoxy and oxime sealants an amino-alkoxy-silane, or one of its derivatives, or a silane with Si--N bonds, to ensure adhesion to plastics, particularly to PVC, PMMA and PC. However, we have found that with silica filled alkoxy compositions, the presence of such amino-silane is not sufficient to provide reliable adhesion on plastics other than PVC and that another solution has to be found to achieve good adhesion to PMMA and PC. Surprisingly we have now found that such compositions which include certain silicon organic polymers as an adhesion promoter have exceedingly good adhesion to commonly used building materials. According to the present invention there is provided a method of forming an elastomeric mass between surfaces which is adherent to at least two such surfaces which method comprises introducing between the surfaces a mass of a moisture curable composition which comprises a mixture and/or a reaction product of a polymeric material having not less than two groups bonded to silicon which are independently selected from hydroxyl and other hydrolyzable groups, an alkoxysilane curative, a finely divided filler and catalyst material for catalyzing a condensation reaction between the polymeric material and the alkoxysilane curative, characterized in that the composition further includes an adhesion promoter which comprises a silicone-organic copolymer consisting of units (i) according to the general formula R.sub.a R'SiO.sub.(4-9)/2 and units (ii) according to the general formula R.sub.b R'SiO.sub.(3-b)/2 where each R is the same or different and represents a monovalent hydrocarbon group having up to 20 carbon atoms, each a is the same or different and has a value from 0 to 3, each b is the same or different and has a value from 0 to 2 and R' is the same or different and represents an oxyalkylene chain R.sup.6 (C.sub.2 H.sub.4 O).sub..times. (C.sub.3 H.sub.6 O).sub.y Z where R.sup.6 represents a hydrocarbon linkage to a silicon atom, each Z is the same or different and represents H or a carboxylic acid residue, each x is the same or different and has a value from 0 to 20 and each y is the same or different and has a value from 0 to 20 and x+y has a value from 3 to 40. The polymeric material used in the method of the present invention may be represented by the general formula X--A--X where A may be any desired organic or siloxane molecular chain, for example a polyoxyalkylene chain or more preferably a polydiorgano-siloxane chain and thus preferably includes siloxane units R".sub.s SiO.sub.(4-s)/2 in which R" represents an alkyl group having from 1 to 6 carbon atoms, for example a methyl group, a vinyl group or a phenyl group, or fluorinated alkyl group and s has a value of 0, 1 or 2. Preferred materials are linear materials, i.e. preferably s=2 for all units. Preferred materials have polydiorgano-siloxane chains according to the general formula--(R".sub.2 SiO).sub.t --in which each R" represents a methyl group and t has a value from about 200 to about 1500. Suitable materials have viscosities of the order of about 500 mPa.s to about 200,000 mPa.s. The groups X of the polymeric material are hydroxyl or other hydrolyzable groups and may be selected, for example, from --R".sub.2 SiOH, --R"Si(OR.sup.5).sub.2, --Si(OR.sup.5).sub.3, --R".sub.2 SiOR.sup.5 or --R".sub.2 SiR"'SiR".sub.p (OR.sup.5).sub.3-p where R" is as aforesaid, and is preferably methyl, R"' is a divalent hydrocarbon group which may be interrupted by one or more siloxane spacers having up to 6 silicon atoms, R.sup.5 represents an alkyl or oxyalkyl group in which the alkyl groups have up to 6 carbon atoms and p has the value 0,1 or 2. In the composition used in the method of the present invention the alkoxysilane curative is preferably of the general formula R".sub.4-n Si(OR.sup.5).sub.n wherein R" and R.sup.5 are as aforesaid and n has a value of 2, 3 or 4. Preferred silanes are those wherein R" represents methyl, ethyl or vinyl, R.sup.5 represents methyl or ethyl and n is 3. Examples of operative silanes are methyl tri(methoxy) silane, vinyl trimethoxy silane, methyl triethoxy silane, and vinyl triethoxy silane. A sufficient amount of this silane is employed to ensure adequate stability of the composition during storage and adequate crosslinking of the composition when exposed to atmospheric moisture. The moisture curable composition used in the method of the present invention comprises a silicone-organic copolymer as an adhesion promotor (hereinafter also referred to as silicone glycol) consisting of units (i) according to the general formula R.sub.a SiO.sub.(4-a)/2 and units (ii) according to the general formula R.sub.b R'SiO.sub.(3-b)/2 where each R is the same or different and represents a monovalent hydrocarbon group having up to 20 carbon atoms, each a is the same or different and has a value from 0 to 3, each b is the same or different and has a value from 0 to 2 and each R' is the same or different and represents an oxyalkylene chain R.sup.6 (C.sub.2 H.sub.4 O).sub.x (C.sub.3 H.sub.6 O).sub.y Z where R.sup.6 represents a hydrocarbon linkage to a silicon atom, each Z is the same or different and represents H or a carboxylic acid residue, each x is the same or different and has a value from 0 to 20 and each y is the same or different and has a value from 0 to 20 and x+y has a value from 3 to 40. In preferred materials, the units (ii) are chain units and b has the value 1. Preferred materials are according to the general formula R.sub.3 SiO(R.sub.2 SiO).sub.s (RR'SiO).sub.t SiR.sub.3 in which s has a value of 10 to 125 and t has a value of 2 to 15 and most preferably the groups R are either methyl groups or groups C.sub.12 H.sub.25. The groups R' may include either oxyethylene groups or oxypropylene groups or both and these groups preferably provide no more than 40% by weight of the silicone organic polymer. The compositions used in the method of this invention preferably contain a silica as the finely divided filler, such as high surface area fume and precipitated silicas, and may also contain as optional constituents other ingredients which are conventional to the formulation of silicone rubber sealants and the like. For example, the compositions will normally contain one or more other finely divided, reinforcing or extending fillers such as crushed quartz, diatomaceous earths, calcium carbonate, barium sulphate, iron oxide, titanium dioxide and carbon black. The proportion of such fillers employed will depend on the properties desired in the elastomer-forming composition and the cured elastomer. Usually the filler content of the composition will reside within the range from about 5 to about 150 parts by weight per 100 parts by weight of the polymeric material. Other ingredients which may be included in the composition are catalysts and co-catalysts for increasing the rate of cure of the composition, pigments, plasticizers, agents (usually organosilicon compounds) for treating fillers, Theological additives for improving toolability of the composition and adhesion improving substances for example .gamma.-aminopropyl triethoxysilane. Preferred catalysts are titanium compounds, for example tetra isopropyl titanate and tetra n butyl titanate, which can provide improved surface cure time and skin elasticity of the cured elastomeric mass compared to elastomeric masses formed by condensation reactions catalyzed by other catalysts. Co-catalysts are well known in the art and include the metal salts of carboxylic acids, for example lead octoate and dibutyltin dilaurate, dibutyltin diacetate and stannous octoate. If a more rapid cure is desired, a chelate, for example an acetyl acetonate, may be added to the mixture. Acetyl acetonate materials conventionally used as accelerators for titanium catalysts may be employed, for example ethyl aceto acetate and methyl aceto acetate. Another ingredient which can be employed as a plasticizer and to reduce the modulus of the cured elastomer is a polydimethylsiloxane having terminal triorganosiloxy groups wherein the organic substituents are e.g. methyl, vinyl or phenyl or combinations of these groups. These polydimethylsiloxanes normally have a viscosity of from about 100 to about 100,000 mPa.s at 25.degree. C. and can be employed in amounts up to about 80 parts per 100 parts by weight of the polymeric material. The composition can be prepared by mixing the ingredients in any order and employing any suitable mixing equipment. It is generally preferred to add the curing catalyst after mixing together the polymeric material and the curative silane. Optional additional ingredients may be incorporated at any stage of the mixing operation but are preferably added after the catalyst. After mixing, the compositions should be stored under substantially anhydrous conditions, for example in sealed containers, until required for use. The composition may be formulated as single part formulations which are stable in storage but cure on exposure to atmospheric moisture and may be employed in a variety of applications, for example as coating, caulking and encapsulating materials. It is, however, particularly suitable for sealing joints, cavities and other spaces in articles and structures which are subject to relative movement. It is thus particularly suitable as glazing sealants and for sealing building structures. It has desired cure properties to provide cured seals of modulus sufficiently low for most industry standards and elongation to break which is sufficiently high for most industry standards. According to the present invention there is also provided a method for promoting adherence of an elastomeric mass to two or more surfaces, which elastomeric mass is formed from a moisture curable composition comprising a mixture and/or a reaction product of a polymeric material having not less than two groups bonded to silicon which are independently selected from hydroxyl and other hydrolyzable groups, an alkoxysilane curative, a finely divided filler and catalyst material for catalyzing a condensation reaction between the polymeric material and the alkoxysilane curative, characterized in that the method comprises including an adhesion promoter in the composition, which adhesion promoter comprises a silicone organic copolymer consisting of units (i) according to the general formula R.sub.a SiO.sub.(4-a)/2 and units (ii) according to the general formula R.sub.b R'SiO.sub.(3-b)/2 where R, a, b and R' are as defined herein above. According to the present invention there is further provided a moisture curable composition which comprises a mixture and/or a reaction product of a polymeric material having not less than two groups bonded to silicon which are independently selected from hydroxyl and other hydrolyzable groups, an alkoxysilane curative, a finely divided filler and catalyst material for catalyzing a condensation reaction between the polymeric material and the alkoxysilane curative, characterized in that the composition further includes an adhesion promoter which comprises a silicone-organic copolymer consisting of units (i) according to the general formula R.sub.a SiO.sub.(4-a)/2 and units (ii) according to the general formula R.sub.b R'SiO.sub.(3-b)/2 where R, a, b and R' are as defined herein above. The present invention will now be illustrated by way of example embodiments thereof. In the description all parts are expressed by weight, all viscosities are at 25.degree. C., Me represents methyl, PMMA represents polymethylmethacrylate and SNJF represents the Syndicat National des Joints et Facades of France. |
| PATENT EXAMPLES | This data is not available for free |
| PATENT PHOTOCOPY | Available on request |
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