Liquid organopolysiloxane composition for matting and cured article having a matted surface

Abstract

A liquid organopolysiloxane composition is provided. This composition can readily form a cured article having a matted surface without requiring separate step such as mechanical surface roughening, and this composition is well adapted for use as a potting material or a coating material in electric and electronic components such as LED. An article having a matted surface produced by curing such composition is also provided. The liquid organopolysiloxane composition for matting comprises (A) 100 parts by weight of a thermosetting liquid organopolysiloxane composition, and (B) 0.1 to 100 parts by weight of a hollow filler having a melting point of at least 150° C., a specific weight of 0.01 to 0.8, and a particle size of up to 200 μm. The composition has a viscosity at room temperature of 100 to 100,000 mPa·s. The resulting cured article has a surface glossiness of up to 40.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2006-158090 filed in Japan on Jun. 7, 2006, the entire contents of which are hereby incorporated by reference.TECHNICAL FIELD[0002]This invention relates to a flowable liquid organopolysiloxane composition for producing a cured article having a matted surface. This invention also relates to a cured article having a matted surface.BACKGROUND ART[0003]A liquid organopolysiloxane (silicone rubber) composition which is flowabile at room temperature and which cures by heating or the like has been widely used as a potting material or coating material in various fields such as construction and industry.[0004]An article produced by curing such liquid silicone rubber composition had a smooth and glossy surface, and when such composition is used for sealing, adhesion, or electric insulation of a liquid crystal display (LED), the surface of the cured co...

AI Technical Summary

Benefits of technology

[0012]The present invention has been completed for the purpose of overcoming the situation as described above, and an object of the present invention is to provide a liquid organopolysiloxane composition which can readily form a cured article having a matted surface without requiring separate step such as mechanical surface roughening, and which is well adapted for use as a potting material or coating material in an electric or electronic components such as LED. Another object of the invention is to provide an article having a matted surface produced by curing such composition.

[0021]The liquid organopolysiloxane composition for matting of the present invention is readily capable of providing a cured article having a matted surface without additionally conducing a separate step such as mechanical surface roughening by using a file.

Problems solved by technology

Such reflection resulted in the loss of image contrast which in turn resulted in the poor visibility, and also, in the poor reliability of the detection system receiving the light beam from the LED.

However, mechanical surface roughening of the cured article resulted in the increase in the number of steps, which invited increase in the production cost.

Use of the optical device with higher luminance also resulted in the increased cost.

However, incorporation of the inorganic filler at a high content was requried in order to provide a sufficiently matted surface by this method, and such incorporation of the inorganic filler at a high content resulted in an increased viscosity of the composition, and hence, in a marked decrease in the flowability.

Accordingly, use of such composition as a potting material or coating material was difficult.

In the case of these silicone rubber compositions, the filler had a specific weight higher than that of the silicone rubber used for the base component, and these compositions were associated with the risk of filler separation during the storage.

Prevention of such separation required increase in the filler content or increase in the viscosity of the base component, which sacrificed flowability of the composition.

These silicone rubber composition, however, had a drawback that formation of the matted surface by the migration of the hydrocarbon to the surface of the cured article required time.

Control of the degree of matting was also difficult since the degree of matting differed even if the hydrocarbon content in the composition were the same since migration proceeded at a different rate when surface area of the hydrocarbon per unit volume was different.

This method, however, has the drawback that the large amount of silane coupling agent incorporated results in the inferior rubber property of the cured article.