Rhodia Chimie

Bluestar Silicones France

Jacques Kieffer

Didier Dhaler

John White

Jean-Paul Benayoun

The invention relates to crosslinkable or crosslinked silicone compositions capable of being used to form a water-repellent and release coating for a flexible support made of paper or of polymer, in particular a heat-sensitive flexible support. These compositions are of the type of those comprising crosslinking polyorganosiloxanes carrying SiH units and unsaturated, preferably vinylated, polyorganosiloxanes capable of reacting with the crosslinking agent by polyaddition in the presence of platinum to form the release crosslinked coating on the flexible support. The targeted aim is to make possible the instantaneous crosslinking at low temperature (85-90&#xb0; C.) of such silicone compositions coated on flexible supports at a very high speed. To achieve this aim, the invention provides for the use of specific crosslinking agents composed of POSs hydrogenated at the chain end and in the chain. The invention also relates to the silicone compositions of solvent-free type or of emulsion type comprising the Si-Vi POS, the SiH POS crosslinking agent &#x3b1;,&#x3c9;-bis(hydrodimethylsiloxyl)poly(hydromethyl)-(dimethyl)siloxane, and the platinum catalyst, inter alia. Applications: release silicone coatings obtained by crosslinking/polyaddition for heat-sensitive flexible supports, for example polymeric films made of polyethylene.

Crosslinking agent for a silicone composition which can be crosslinked at low temperature based on a hydrogenated silicone oil comprising Si-H units at the chain end and in the chain

The invention concerns crosslinkable silicone compositions, useful for forming water-repellent and release coating for flexible heat-sensitive support. Said compositions comprise crosslinking polyorganosiloxanes (POS) bearing &#x2261;Si&#x2014;H units and unsaturated POS, for example &#x2261;Si-Vi vinyl-containing POS, capable of reacting with the crosslinking agent by polyaddition, in the presence of platinum to form a release crosslinked coat on the flexible support. The invention aims at instantaneously enabling low platinum content crosslinking of such silicone compositions, coated at high speed. Therefor, the invention provides for the use of particular crosslinking agents consisting of hydrogenated POS comprising at least three hydrogen atoms bound to the silicon located at chain end and in the chain. The invention also concerns solvent-free or emulsion-type silicone compositions comprising the &#x2261;Si-Vi POS (I.1), the crosslinking agent &#x2261;Sl-H POS (l.2) and the platinum catalyst among others. The invention is useful for coating flexible supports, for example made of Liss&#xe9; BEKK&#x3e;1000 paper.

Crosslinking agent for a crosslinkable silicone composition with a low level of platinum based on a hydrogenated silicone oil comprising Si-H units at the chain end and in the chain

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Neyron, France

Jacques Kieffer