Dow Corning Corporation

Peter Lamont

James Anderson Beck

Jary David Jensen

Joseph Norbert Clark

Phillip Joseph Griffith

Carl M Monroe

Joseph T Braun

Olgerts Skostins

Lori Jean Conway

Edward Joseph Benson

A platinum group-metal curing liquid silicone rubber compositions having improved physical properties such as tear and heat-aging, especially at durometers below about 35 and above about 65. The present inventors have unexpectedly discovered that the addition of diorganohydrogensiloxy end-blocked polydiorganosiloxanes and triorganosiloxy end-blocked polydiorganosiloxanes having a viscosity greater than about 10 Pa.cndot.s at 25.degree. C. to liquid silicone rubber compositions can provide for the described improved properties.

Use of high molecular weight organopolysiloxanes to improve physical

The instant invention pertains to a method of producing silicone pressure sensitive adhesives wherein the method comprises (I) combining together (A) a benzene soluble, hydroxyl containing organopolysiloxane resin consisting essentially of R.sub.3 SiO.sub.1/2 siloxane units and SiO.sub.4/2 siloxane units, wherein R is a monovalent radical selected from the group consisting of hydrocarbon and halogenated hydrocarbon radicals having from 1 to 10 carbon atoms; there being from 0.5 to 1.5 R.sub.3 SiO.sub.1/2 units for every SiO.sub.4/2 units and there being 1.0 to 4 wt %, based on FTIR, hydroxyl functionality and (B) a hydroxyl containing polydiorganosiloxane having a viscosity of .gtoreq.100 mPa's and (C) a catalyst selected from the group consisting of a weak organic acid or metal salt thereof; and thereafter (II) heating the mixture of (A), (B) and (C) for a time sufficient to produce the silicone pressure sensitive adhesive.

Method of making silicone pressure sensitive adhesives

Siloxanyl-phosphate mixtures are prepared by reacting cyclopolydimethylsiloxane and a silylphosphate mixture. The siloxanyl-phosphate mixture is a mixture of 5 to 30 weight percent of a monosiloxanyl-phosphate of the formula ##STR1## 70 to 85 weight percent of a disiloxanyl-phosphate of the formula ##STR2## 2 to 11 weight percent of a trisiloxanyl-phosphate of the formula wherein x has an average value of from 3 to 30.

Siloxanyl-phosphate mixture and its use in stabilizing metal silanolates

Silylphosphate mixtures are prepared by slowly adding phosphoric acid to hexamethyldisiloxane under reflux while removing the by-produced water and after the phosphoric acid is added, the temperture is increased to from 150.degree. C. to 170.degree. C. to recover the silylphosphate mixture residue. The mixture has from 10 to 30 weight percent of a monosilyl phosphate of the formula

Method of preparing a silyphosphate mixture, silyphosphate mixture and

Silicone rubber compositions prepared from polydiorganosiloxane and small amounts of alkali metal hydrogen phosphates or alkali metal hydrogen phosphites improve the properties of the silicone rubber, such as compression set and flame retardancy.

Silicone rubber containing alkali metal salts of phosphoric acid and

A method of reducing the reaction between polydiorganosiloxane gum and reinforcing silica, which causes 'creping', has been discovered. The method mixes crude polydiorganocyclosiloxane with a carbonate or bicarbonate salt of potassium or cesium, heats the mixture, then filters to remove the salt. The treated material can be further purified by stripping this filtered material to give a polydiorganocyclosiloxane having a hydroxyl content of less than 1 part per million of polydiorganocyclosiloxane.

Method of reducing activity of silicone polymers

A method of producing an improved extruding silicone rubber stock consists essentially of mixing together a polydiorganosiloxane having a Williams Plasticity Number of from 125 to 180 and a get slope activity of less than 25 and a reinforcing silica filler having a surface area of greater than 150 m.sup.2 /g and a hydrophobic surface from a silane treatment to give a stock which has a Garvey rating of greater than 3.5 at an extrusion rate of 20 rpm.

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Midland, MI, United States of America

Peter Lamont