Thermoplastic polyester resin composition and molded article

Abstract

A thermoplastic polyester resin composition has an excellent retention stability and is capable of producing a molded article excellent in mechanical properties and heat resistance as well as in long-term hydrolysis resistance; and the molded article. The thermoplastic polyester resin includes 100 parts by weight of a thermoplastic polyester resin (A) and 0.1 to 10 parts by weight of a biphenyl aralkyl-type epoxy resin or cyclopentadiene-type epoxy resin (B) of a specific type.

What is claimed is: 
     
         1 . A molded article obtained by melt-molding a thermoplastic polyester resin composition,
 wherein the thermoplastic polyester resin composition comprises 100 parts by weight of a thermoplastic polyester resin (A), and 0.1 to 10 parts by weight of a novolac type epoxy resin (B) represented by formula (1);   
       
         
           
           
               
               
           
         
       
       wherein, in formula (1), X represents a divalent group represented by formula (3); 
       
         
           
           
               
               
           
         
         wherein R 1  to R 2  each independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 10 carbon atoms, and they may be the same or different from each other; and R 5  represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms; 
         n represents a value of 2 to 10; 
         a, c, and d each independently represents a value of 0 to 4, and b represents a value of 0 to 3, and a ratio (a blend concentration of epoxy groups/a blend concentration of carboxyl end groups) of the blend concentration (eq/g) of the epoxy groups derived from the novolac type epoxy resin (B) represented by formula (1) to the blend concentration (eq/g) of the carboxyl end groups derived from the thermoplastic polyester resin (A), in the thermoplastic polyester resin composition, is 1 to 8, 
         the thermoplastic polyester resin (A) is a polymer or a copolymer comprising as main structural units a residue of an aromatic dicarboxylic acid or an ester-forming derivative thereof and a residue of an aliphatic diol or an ester-forming derivative thereof, and 
         the thermoplastic polyester resin (A) consists of a polymer or a copolymer selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polycyclohexane dimethylene terephthalate, polyethylene naphthalate, polypropylene naphthalate, polybutylene naphthalate, polyethylene isophthalate/terephthalate, polypropylene isophthalate/terephthalate, polybutylene isophthalate/terephthalate, polyethylene terephthalate/naphthalate, polypropylene terephthalate/naphthalate and polybutylene terephthalate/naphthalate. 
       
     
     
         2 . The molded article according to  claim 1 , wherein the concentration of the carboxyl end groups with respect to the amount of the thermoplastic polyester resin (A) in the thermoplastic polyester resin composition is 20 eq/t or less. 
     
     
         3 . The molded article according to  claim 1 , wherein the concentration of the epoxy groups in the thermoplastic polyester resin composition is 5 eq/t or more. 
     
     
         4 . The molded article according to  claim 1 , wherein the thermoplastic polyester resin composition further comprises a phosphorus-based stabilizer (C) in an amount of 0.01 to 1 part by weight with respect to 100 parts by weight of the thermoplastic polyester resin (A). 
     
     
         5 . The molded article according to  claim 1 , wherein the thermoplastic polyester resin composition further comprises a monofunctional epoxy compound (D) in an amount of 0.01 to 1 part by weight with respect to 100 parts by weight of the thermoplastic polyester resin (A). 
     
     
         6 . The molded article according to  claim 1 , wherein the thermoplastic polyester resin composition further comprises a reaction catalyst (E) in an amount of 0.001 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic polyester resin (A). 
     
     
         7 . The molded article according to  claim 6 , wherein the ratio (the blend concentration of the reaction catalyst/the blend concentration of the epoxy groups) of the blend concentration (mol/g) of the reaction catalyst (E) to the blend concentration (eq/g) of the epoxy groups derived from the novolac type epoxy resin (B) represented by formula (1), in the thermoplastic polyester resin composition, is 0.01 to 0.1. 
     
     
         8 . The molded article according to  claim 6 , wherein the reaction catalyst (E) contains a compound containing nitrogen or phosphorus. 
     
     
         9 . The molded article according to  claim 6 , wherein the reaction catalyst (E) contains an amidine compound. 
     
     
         10 . The molded article according to  claim 1 , wherein the thermoplastic polyester resin (A) consists of a polymer or a copolymer selected from the group consisting of polybutylene terephthalate, polyethylene terephthalate, polypropylene terephthalate, polyethylene naphthalate, and polycyclohexane dimethylene terephthalate. 
     
     
         11 . The molded article according to  claim 1 , wherein the thermoplastic polyester resin (A) consists of polybutylene terephthalate.