Cycloolefin resin composition, molded article thereof, and mirror

Abstract

A molded article is formed by molding a cycloolefin resin composition, in which the cycloolefin resin composition contains a cycloolefin resin and silica particles, the silica particles have an average primary particle size of 10 nm to 150 nm, the cycloolefin resin composition has a silica particle content of 15% by weight to 70% by weight, and the molded article has a linear expansion coefficient of 50×10 −6 /degrees (Celsius) or less in the temperature range of 0 degrees (Celsius) to 80 degrees (Celsius).

1 . A molded article formed by molding a cycloolefin resin composition,
 wherein the cycloolefin resin composition contains a cycloolefin resin and silica particles,   wherein the silica particles have an average primary particle size of 10 nm to 150 nm,   the cycloolefin resin composition has a silica particle content of 15% by weight to 70% by weight, and   the molded article has a linear expansion coefficient of 50×10 −6 /degrees (Celsius) or less in the temperature range of 0 degrees (Celsius) to 80 degrees (Celsius).   
     
     
         2 . The molded article according to  claim 1 ,
 wherein the silica particles are treated with hexamethyldisilazane.   
     
     
         3 . The molded article according to  claim 1 ,
 wherein the molded article has an average root-mean-square surface roughness (Rq) of 10 nm or less.   
     
     
         4 . A mirror comprising:
 a molded article formed by molding a resin composition; and   a reflective layer arranged on an optically effective surface of the molded article,   wherein the resin composition is a cycloolefin resin composition containing a cycloolefin resin and silica particles,   wherein the silica particles have an average primary particle size of 10 nm to 150 nm,   the cycloolefin resin composition has a silica particle content of 15% by weight to 70% by weight, and   the molded article has a linear expansion coefficient of 50×10 −6 /degrees (Celsius) or less in the temperature range of 0 degrees (Celsius) to 80 degrees (Celsius).   
     
     
         5 . The mirror according to  claim 4 ,
 wherein the silica particles are treated with hexamethyldisilazane.   
     
     
         6 . The mirror according to  claim 4 ,
 wherein the molded article has an optically effective surface with an average root-mean-square surface roughness (Rq) of 10 nm or less.   
     
     
         7 . The mirror according to  claim 4 ,
 wherein the molded article has an optically effective surface with an average root-mean-square surface roughness (Rq) of 4 nm or less.   
     
     
         8 . The mirror according to  claim 4 ,
 wherein the mirror is used for a scanner unit of a multifunction device.   
     
     
         9 . A cycloolefin resin composition comprising:
 a cycloolefin resin; and   silica particles,   wherein the silica particles have an average primary particle size of 10 nm to 150 nm, and   the cycloolefin resin composition has a silica particle content of 15% by weight to 70% by weight.   
     
     
         10 . The resin composition according to  claim 9 ,
 wherein the silica particles are treated with hexamethyldisilazane.