General Electric Company

Susan E Hayes

Richard P Eckberg

James E Doin

A process is provided for preparing coating compositions suitable for a primerless application to plastic substrates, which includes catalyzed prehydrolysis of a silylated UV screen component. Preferred embodiments employ catalyzing agents which can be removed from the prehydrolysis solution. Coating compositions made by the process are also disclosed.

Silicone resin coating composition adapted for primerless adhesion to

Alkoxysilanes are hydrolyzed with water in the presence of various hydrolysis catalysts. The hydrolysis catalysts include the solid oxides of the Group IIa metals and solid acid catalysts. The solid acid catalysts are used in conjunction with neutralizing agents and optionally with condensation catalysts. Generally, the process for hydrolyzing alkoxysilanes comprises: mixing an alkoxysilane, a stoichiometric excess of water and an effective catalytic amount of hydrolysis catalyst selected from the group consisting of a solid oxide of a Group IIa metal, a solid acid catalyst and mixtures thereof; neutralizing the hydrolysis mixture with a sufficient amount of neutralizing agent, for example, magnesium oxide; and separating the hydrolysis product from the mixture. When a Group IIa metal oxide hydrolysis catalyst is used, the liquid portion of the hydrolysate is neutral, and no additional neutralizing agent is required in the mixture. By the process of the present invention, the average chain length of silanol-stopped polysiloxanes can be controlled. A stabilized, crystalline tetramethyldisiloxane diol and a crystalline dimethyldisilanol have also been prepared by modified catalytic hydrolysis processes using solid acid catalysts to catalyze the hydrolysis of dimethyldimethoxysilane with water.

Hydrolysis of alkoxysilanes

An ultraviolet light curable silicone pressure sensitive adhesive is provided which is comprised of an epoxy functional silicone polymer and a combination of standard MQ silicone resins or epoxy functional MQ silicone resins, which can be cured to an adhesive composition in the presence of certain bis(aryl)halonium salt catalysts.

Ultraviolet curable silicone adhesives

A method for stabilizing silanol hydrolysates of organosilanes in an acid medium is described. The method comprises adding a neutralizing agent containing a chelatable metal ion to the silanol hydrolysate in an acid medium to reduce the acidity of the medium; removing solids from the medium; and adding a chelating agent to form a chelate with metal in the medium. In a preferred embodiment, methyltrimethoxysilane is hydrolyzed with an excess of slightly acidic water; calcium carbonate neutralizing agent is added thereto to reduce the acidity of the medium; excess calcium carbonate and other solids in the medium are removed by filtration; and acetylacetone is added as a chelating agent to form a chelate or to interact with the calcium from the calcium carbonate neutralizing agent in the medium. The process of this invention stops haze formation in the products formed by the process of the invention and substantially extends the shelf life of silanol hydrolysates of organolsilanes.

Growing community of inventors

Schenectady, NY, United States of America

Susan E Hayes