Curing-reactive organopolysiloxane resin, pressure-sensitive adhesive composition using same, and use thereof

Abstract

A curing-reactive organopolysiloxane composition is provided. The composition generally forms a pressure-sensitive adhesive layer which is curable by a hydrosilylation reaction, has excellent adhesiveness and handleability, and is capable of maintaining high transparency over an extended period of time without developing problems such as discoloration or coloration, even when subjected to long-term aging at a high temperature and even when exposed to high-energy rays such as UV rays over an extended period of time. The curing-reactive organopolysiloxane composition can be cured via hydrosilylation reaction. A content of platinum-based metal among a solid content is in the range of from 0.1 to 50 ppm. An adhesive force of a cured layer with a thickness of 50 μm obtained by curing the composition is not less than 0.02N/25 mm. A pressure-sensitive adhesive layer obtained by curing the composition, and an electronic part or a display device using the same, are also provided.

1 . A curing-reactive organopolysiloxane composition including a hydrosilylation reaction, comprising a content of platinum-based metal among a solid content within a range of from 0.1 to 50 ppm, and an adhesive force of a polymethyl methacrylate sheet, with a thickness of 2 mm provided with a cured layer with a thickness of 50 μm obtained by curing the composition, as measured at a tensile speed of 300 mm/min using a 180° peel test method according to JIS Z 0237, of not lower than 0.02 N/25 mm. 
     
     
         2 . The curing-reactive organopolysiloxane composition according to  claim 1 , wherein a b* value, which is measured with an L*a*b* color system as prescribed in JIS Z 8729, of a cured layer with a thickness of 100 μm obtained by curing the composition is not greater than 0.15. 
     
     
         3 . The curing-reactive organopolysiloxane composition according to  claim 1  or  2 , wherein when a cured layer with a thickness of 100 μm obtained by curing the composition is aged for 300 hours at 105° C. or irradiated for 75 hours with UV light using a mercury lamp with an intensity of 12 mW/cm2 at 365 nm and an intensity of 3.5 mW/cm2 at 254 nm, a change (Δb*) in a b* value measured with an L*a*b* color system as prescribed in JIS Z 8729 is not greater than 0.20. 
     
     
         4 . The curing-reactive organopolysiloxane composition according to any one of  claims 1  to  3 , wherein a content of platinum-based metal among solid content is in a range of from 0.1 to 30 ppm; a cured layer with a thickness of 100 μm obtained by curing the composition is substantially transparent; a b*value thereof measured with an L*a*b* color system as prescribed in JIS Z 8729 is not greater than 0.10; and when the cured layer is aged for 300 hours at 105° C. or irradiated for 75 hours with UV light using a mercury lamp with an intensity of 12 mW/cm2 at 365 nm and an intensity of 3.5 mW/cm2 at 254 nm, a change (Δb*) in a b* value measured with an L*a*b* color system as prescribed in JIS Z 8729 is not greater than 0.15. 
     
     
         5 . The curing-reactive organopolysiloxane composition according to any one of  claims 1  to  4 , wherein the composition contains the following components (A) to (C):
 (A) a straight-chain or branched-chain organopolysiloxane having a number of alkenyl groups greater than 1 on average in the molecule; 
 (B) an organopolysiloxane resin; and 
 (C) an organohydrogenpolysiloxane having at least two Si—H bonds in the molecule. 
 
     
     
         6 . The curing-reactive organopolysiloxane composition according to  claim 5 , wherein a molar ratio of silicon-bonded hydrogen atom (SiH) groups in component (C) to alkenyl groups in the composition is in a range of from 0.1 to 100. 
     
     
         7 . The curing-reactive organopolysiloxane composition according to  claim 5  or  6 , wherein at least a part of component (A) is (A1) a raw rubber-like alkenyl group-containing organopolysiloxane having a viscosity of not less than 100,000 mPa-s at 25° C. or having a plasticity in a range of from 50 to 200 as measured in accordance with a method as prescribed in JIS K6249;
 at least a part of component (B) is a resin which consists of (B1) R3SiO1/2 units (M units) and SiO4/2 units (Q units) and which may have a hydroxyl group or a hydrolyzable group, wherein R is a monovalent organic group and not less than 90 mol % of R is an alkyl group or a phenyl group having a carbon number of from 1 to 6; and 
 a content of a vinyl (CH2═CH) portion in the alkenyl group in component (A1) is in a range of from 0.005 to 0.400 wt. %, and a content of component (B) is in a range of from 1 to 500 parts by mass with respect to a total of 100 parts by mass of components (A) and (C) in the composition. 
 
     
     
         8 . The curing-reactive organopolysiloxane composition according to any one of  claims 1  to  7 , further containing at least one type of (D) curing retarder. 
     
     
         9 . The curing-reactive organopolysiloxane composition according to  claim 8 , wherein a viscosity of the composition after 8 hours at room temperature from immediately after preparation of the composition is not greater than 1.5 times that of a viscosity immediately after the preparation of the composition, and the composition is curable at 80 to 200° C. 
     
     
         10 . A pressure-sensitive adhesive composition comprising the curing-reactive organopolysiloxane composition according to any one of  claims 1  to  9 . 
     
     
         11 . A cured product obtained by curing the curing-reactive organopolysiloxane composition according to any one of  claims 1  to  9 . 
     
     
         12 . A pressure-sensitive adhesive layer obtained by curing the curing-reactive organopolysiloxane composition according to any one of  claims 1  to  9 . 
     
     
         13 . The pressure-sensitive adhesive layer according to  claim 12 , which is film-like and substantially transparent. 
     
     
         14 . A laminate comprising a cured product obtained by curing the curing-reactive organopolysiloxane composition according to any one of  claims 1  to  9  on a film-like substrate. 
     
     
         15 . The laminate according to  claim 14 , wherein the cured layer is a pressure-sensitive adhesive layer, and a release layer for the pressure-sensitive adhesive layer is provided on the film-like substrate. 
     
     
         16 . An electronic material or a member for a display device obtained by curing the curing-reactive organopolysiloxane composition according to any one of  claims 1  to  9 . 
     
     
         17 . An electronic part or a display device containing the electronic material or member for a display device according to  claim 16 . 
     
     
         18 . A display panel or a display comprising the film-like and substantially transparent pressure-sensitive adhesive layer according to  claim 13 . 
     
     
         19 . A touch panel comprising a substrate having a conductive layer formed on one surface; and a cured layer obtained by curing the curing-reactive organopolysiloxane composition according to any one of  claims 1  to  9 , which is attached to the conductive layer of the substrate or a surface on an opposite side thereof. 
     
     
         20 . The touch panel according to  claim 19 , wherein the substrate on which the conductive layer is formed is a resin film or a glass film having an ITO layer formed on one surface.