Epoxy Resin Composition For Transparent Sheets And Cured Product Thereof

Abstract

To provide an epoxy resin composition that is suitable for producing optical sheets which exhibit excellent transparency, heat resistance, strength, smoothness and light resistance, and a cured product thereof. An epoxy resin composition for optical3 sheets, the composition comprising a polyvalent carboxylic acid (A) represented by formula (I): (wherein, R 1 's each independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or a carboxyl group; q represents the number of substituent R 1 's, and represents an integer from 1 to 4; and P represents any one of the following x, y and z): (wherein, there may be a plural number of R 2 's per ring, and R 2 's each independently represent a hydrogen atom or a methyl group; and * represents a bonding site linked to the oxygen atom; y. A linear alkylene linker having 6 to 20 carbon atoms, with a main chain having 3 or more carbon atoms and being substituted with an alkyl group in at least one site); (wherein, R's each independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or a carboxyl group; and * represents a bonding site linked to the oxygen atom, and an epoxy resin (B) having an aliphatic cyclic structure in the molecule).

1 . A cured product obtainable by curing an epoxy resin composition for optical sheets, the composition comprising a polyvalent carboxylic acid (A-z) obtained by reacting a compound represented by formula (IV): 
       
         
           
           
               
               
           
         
         wherein R exists in plurality and R's each independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or a carboxyl group, and 
         a compound represented by formula (V): 
       
       
         
           
           
               
               
           
         
         wherein R 1 's each independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or a carboxyl group; and q represents the number of substituent R.sup.1's and represents an integer from 1 to 4, and 
         an epoxy resin (B) having an aliphatic cyclic structure in the molecule, and the cured product having a refractive index at 25° C. of 1.50 or higher. 
       
     
     
         2 . A cured product obtainable by impregnating a glass cloth with the epoxy resin composition comprising a polyvalent carboxylic acid (A-z) obtained by reacting a compound represented by formula (IV): 
       
         
           
           
               
               
           
         
         wherein R exists in plurality and R's each independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or a carboxyl group, and 
         a compound represented by formula (V): 
       
       
         
           
           
               
               
           
         
         wherein R 1 's each independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or a carboxyl group; and q represents the number of substituent R.sup.1's and represents an integer from 1 to 4, and 
         an epoxy resin (B) having an aliphatic cyclic structure in the molecule, and the cured product having a refractive index at 25° C. of 1.50 or higher. 
       
     
     
         3 . The cured product according to  claim 1 , wherein 50 mol % or more of all R 1 's of the compound represented by formula (V) represent methyl groups and/or carboxyl groups. 
     
     
         4 . The cured product according to  claim 2 , wherein 50 mol % or more of all R 1 's of the compound represented by formula (V) represent methyl groups and/or carboxyl groups. 
     
     
         5 . The cured product according to  claim 1 , wherein the compound represented by formula (V) represents at least one acid anhydride selected from methylhexahydrophthalic anhydride and cyclohexane-1,2,4-tricarboxylic acid anhydride. 
     
     
         6 . The cured product according to  claim 2 , wherein the compound represented by formula (V) represents at least one acid anhydride selected from methylhexahydrophthalic anhydride and cyclohexane-1,2,4-tricarboxylic acid anhydride. 
     
     
         7 . The cured product according to  claim 1 , wherein the epoxy resin (B) having an aliphatic cyclic structure in the molecule is a compound represented by formula (II): 
       
         
           
           
               
               
           
         
         wherein, R 3  represents an n-valent radical of an aliphatic alcohol obtained by removal of n hydroxyl groups; m represents an average value and represents an integer from 1 to 20; and n represents an integer from 1 to 10. 
       
     
     
         8 . The cured product according to  claim 2 , wherein the epoxy resin (B) having an aliphatic cyclic structure in the molecule is a compound represented by formula (II): 
       
         
           
           
               
               
           
         
         wherein, R 3  represents an n-valent radical of an aliphatic alcohol obtained by removal of n hydroxyl groups; m represents an average value and represents an integer from 1 to 20; and n represents an integer from 1 to 10. 
       
     
     
         9 . The cured product according to  claim 1 , wherein the epoxy resin composition further comprises an aromatic polyfunctional epoxy resin (C) having three or more epoxy groups in the molecule. 
     
     
         10 . The cured product according to  claim 2 , wherein the epoxy resin composition further comprises an aromatic polyfunctional epoxy resin (C) having three or more epoxy groups in the molecule. 
     
     
         11 . The cured product according to  claim 9 , wherein the aromatic polyfunctional epoxy resin (C) having three or more epoxy groups in the molecule is a compound represented by formula (III): 
       
         
           
           
               
               
           
         
         wherein, n represents an integer of 1 or 2. 
       
     
     
         12 . The cured product according to  claim 10 , wherein the aromatic polyfunctional epoxy resin (C) having three or more epoxy groups in the molecule is a compound represented by formula (III): 
       
         
           
           
               
               
           
         
         wherein, n represents an integer of 1 or 2. 
       
     
     
         13 . The cured product according to  claim 9 , wherein the epoxy resin composition further comprises an epoxy resin (D) other than the epoxy resin (B) having an aliphatic cyclic structure and the aromatic polyfunctional epoxy resin (C) having three or more epoxy groups in the molecule, and an acid anhydride. 
     
     
         14 . The cured product according to  claim 10 , wherein the epoxy resin composition further comprises an epoxy resin (D) other than the epoxy resin (B) having an aliphatic cyclic structure and the aromatic polyfunctional epoxy resin (C) having three or more epoxy groups in the molecule, and an acid anhydride. 
     
     
         15 . An optical sheet using the cured product according to  claim 1 . 
     
     
         16 . An optical sheet using the cured product according to  claim 2 .