Low-hygroscopicity low-birefringence resin compositions, molding material, sheet or film obtained therefrom, and optical part

Abstract

Low-hygroscopicity low-birefringence resin compositions. One of the compositions is a resin composition (a) comprising the following polymers (A), and (B) and/or (C). Another is a resin composition (b) comprising the following polymers (A), (B) and (H). Still another is a polymer comprising the following polymers (I) and (J), diphenylsilicone (D), and a phenolic antioxidant (E). (A) A polymer comprising one or more kinds of indene and indene derivatives represented by the following general formula (I). (B) A polymer comprising polystyrene or a polystyrene derivative. (C) A polymer comprising a monomer copolymerizable with styrene or a styrene derivative. (H) A graft polymer having a structure wherein a polymer comprising at least one kind of indene and an indene derivative represented by the general formula (I) bonds to a side chain of a polymer comprising a monomer copolymerizable with styrene or a styrene derivative. (I) A polymer comprising one or more kinds of indene and indene derivatives represented by the general formula (I), wherein the polymer has a heterocyclic structure in a side chain thereof. (J) A polymer comprising styrene or a styrene derivative, and a monomer copolymerizable with styrene or a styrene derivative, wherein the polymer has a carboxyl group and/or a phenolic hydroxyl group in a side chain

1 . A resin composition (a) for use in optical parts, comprising the following polymers (A) and either or both of (B) and (C): 
 (A) a polymer comprising monomer units which are one or more kinds of indene and indene derivatives represented by the following general formula (I);    (B) a polymer consisting of monomer units which are styrene or styrene derivatives;    (C) a polymer comprising monomer units which are styrene or styrene derivatives, and a monomer unit copolymerizable with styrene or a styrene derivative selected from the group consisting of styrene, nucleus-substituted alkylstyrenes, nucleus-substituted aromatic styrenes, α-substituted alkylstyrenes, β-substituted alkylstyrenes, nucleus-substituted alkoxystyrenes, alkyl vinyl ethers, aromatic vinyl ethers, isobutene, diisobutylene, and (meth)acrylic esters having 1 to 8 carbon atoms:                          wherein R 1 , R 2 , R 3 , R 4 , and R 5  may be the same or different, and each represents a hydrogen atom; a monovalent hydrocarbon group containing a nitrogen atom, an oxygen atom or a silicon atom; an alkyl group having 1 to 6 carbon atoms; or a monovalent aromatic hydrocarbon group; X represents a hydrogen atom, a halogen atom, an acyl group, an alkoxy group or a nitrile group; x represents an integer of 0 to 4, and y represents an integer of 1 to 4, where x+y=4, wherein the saturated water absorption is 0.4% or less, and the birefringence in stretching the resin composition by 200% is in the range of −2×10 −6  to 2×10 −6 .    
     
     
         2 . The resin composition (a) according to  claim 1 , wherein a diphenylsilicone (D) and/or a phenolic antioxidant (E) are/is added to the resin composition comprising the polymers (A) and either or both (B) and (C).  
     
     
         3 . (Cancelled)  
     
     
         4 . The resin composition (a) according to  claim 1 , wherein the weight-average molecular weight of the polymer (A) is lower than 80000.  
     
     
         5 . The resin composition (a) according to  claim 1 , wherein the weight-average molecular weight(s) of the polymer (B) and/or the polymer (C) are/is 50000 or higher.  
     
     
         6 . The resin composition (a) according to  claim 1 , wherein the content of the polymer (A) is 30 to 90% by weight of the total of the resin composition (a).  
     
     
         7 - 18 . (Canceled).  
     
     
         19 . A molding material for use in optical parts, the molding material being obtained by molding a resin composition (a) according to  claim 1 .  
     
     
         20 . A sheet for use in optical parts, the sheet being obtained from a resin composition (a) according to  claim 1 .  
     
     
         21 . A film for use in optical parts, the film being obtained from a resin composition (a) according to  claim 1 .  
     
     
         22 . (Canceled)