Dow Corning Corporation

Michael Backer

Valerie Smits

Damien Deheunynck

Francois De Buyl

Steven Swier

Randall Gene Schmidt

Jean De La Croix Habimana

Thomas Chaussee

Sebastien Grofils

Vincent Rerat

Thierry Materne

The invention provides a composition comprising a polyolefin and a polyorganosiloxane in which at least 50 mole % of the siloxane units are D units as herein defined and which contains at least one unsaturated group, characterized in that the unsaturated group is group of the formula &#x2014;X&#x2014;CH&#x2550;CH&#x2014;R&#x2033; (I) or &#x2014;X&#x2014;C&#x2261;C&#x2014;R&#x2033; (II), in which X represents a divalent organic linkage having an electron withdrawing effect with respect to the &#x2014;CH&#x2550;CH&#x2014; or &#x2014;C&#x2261;C&#x2014; bond and/or containing an aromatic ring or a further olefinic double bond or acetylenic unsaturation, the aromatic ring or the further olefinic double bond or acetylenic unsaturation being conjugated with the olefinic unsaturation of &#x2014;X&#x2014;CH&#x2550;CH&#x2014;R&#x2033; or with the acetylenic unsaturation of &#x2014;X&#x2014;C&#x2261;C&#x2014;R&#x2033; and R&#x2033; represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the &#x2014;CH&#x2550;CH&#x2014; or &#x2014;C&#x2261;C&#x2014; bond.

Organopolysiloxanes containing an unsaturated group

The invention provides a process for grafting silane or silicone functionality onto a polyolefin, comprising reacting the polyolefin with an unsaturated monomer (A) containing an olefinic &#x2014;C&#x2550;C&#x2014; bond or acetylenic &#x2014;C&#x2261;C&#x2014; bond and a reactive functional group X in the presence of means capable of generating free radical sites in the polyolefin and with an organosilicon compound (B) having a functional group Y which is reactive with the functional group X of the unsaturated monomer (A), characterized in that the unsaturated monomer (A) contains an aromatic ring or a further olefinic double bond or acetylenic unsaturation, the aromatic ring or the further olefinic double bond or acetylenic unsaturation being conjugated with the olefinic &#x2014;C&#x2550;C&#x2014; or acetylenic &#x2014;C&#x2261;C&#x2014; unsaturation of the unsaturated monomer (A).

Modified polyolefins

The invention relates to a process for grafting hydrolysable silane groups to a polyolefin in which ethylene units, if present, form less than 50% by weight of the total polyolefin. The polyolefin is reacted with an unsaturated silane, having at least one hydrolysable group bonded to Si, or a hydrolysate thereof, in the presence of means capable of generating free radical sites in the polyolefin. The unsaturated silane has the formula R&#x2033;&#x2014;CH&#x2550;CH&#x2014;Z (I) or R&#x2033;&#x2014;C&#x2261;C&#x2014;Z (II) in which Z represents an electron-withdrawing moiety substituted by a &#x2014;SiRR'group wherein R represents a hydrolysable group; R&#x2032; represents a hydrocarbyl group having 1 to 6 carbon atoms; a has a value in the range 1 to 3 inclusive; and R&#x2033; represents hydrogen or a group having an electron withdrawing or any other activation effect with respect to the &#x2014;CH&#x2550;CH&#x2014; or &#x2014;C&#x2261;C&#x2014; bond. The use of an unsaturated silane of the formula R&#x2033;&#x2014;CH&#x2550;CH&#x2014;Z (I) or R&#x2033;&#x2014;C&#x2261;C&#x2014;Z (II) in carrying out the grafting reaction on the polyolefin may give enhanced grafting yield compared to grafting with an olefinically unsaturated silane such as vinyltrimethoxysilane not containing an electron withdrawing moiety Z. The invention permits to provide a silane-modified polyolefin having a high grafting efficiency while limiting/preventing polymer degradation by chain scission. The silane-modified polyolefin can be further reacted with a polar surface, a filler or a polar polymer or reacted on itself to crosslink the polyolefin and obtain enhanced physical properties of the composites made thereof.

The invention relates to a process for grafting hydrolysable silane groups to a polyolefin, comprising reacting the polyolefin with an unsaturated silane, containing an olefinic &#x2014;C&#x2550;C&#x2014; bond or acetylenic &#x2014;C&#x2261;C&#x2014; bond and having at least one hydrolysable group bonded to Si, or a hydrolysate thereof, in the presence of means capable of generating free radical sites in the polymer. The silane contains an aromatic ring or a further olefinic double bond or acetylenic unsaturation, the aromatic ring or the further olefinic double bond or acetylenic unsaturation being conjugated with the olefinic &#x2014;C&#x2550;C&#x2014; or acetylenic &#x2014;C&#x2261;C&#x2014; unsaturation of the silane. The unsaturated silane may also contains electron-withdrawing moiety with respect to the olefinic &#x2014;C&#x2550;C&#x2014; or acetylenic &#x2014;C&#x2261;C&#x2014; bond. The invention permits to provide a silane-modified polyolefin having a high grafting efficiency while limiting/preventing polymer degradation by chain scission. The silane-modified polyolefin can be further reacted with a polar surface, a filler or a polar polymer or reacted on itself to crosslink the polyolefin and obtain enhanced physical properties of the composites made thereof.

Polymers modified by silanes

The present invention relates to a curable rubber composition comprising an organic elastomer, a filler and at least one curing agent for the elastomer. Such curable rubber compositions are widely used in the production of cured rubber articles, such as tires, belts and hoses. The composition contains a branched silicone resin having Si-bonded hydroxyl groups or azo groups. This may lead to a reduction in the mixing energy required for processing, particularly in the energy required in the first (non-productive) mixing phase to give good dispersion of the filler in the organic elastomer. Use of the branched silicone resin can also accelerate cure (vulcanization), thus reducing the required cure time or reducing the amount of cure accelerator required.

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Marbais, Belgium

Michael Backer