Thermosetting resin composition

Abstract

A thermosetting resin composition which produces no free isocyanate even when a carbodiimide compound is used and provides a cured resin having high heat resistance. The thermosetting resin composition makes it possible to reduce the curing temperature, cures in a short time and provides a cured rein having a high glass transition temperature. The thermosetting resin composition comprises: (A) an epoxy resin (component A); and (B) a cyclic carbodiimide compound (component B) including a cyclic structure having one carbodiimide group and represented by the following formula (B-i) in which first nitrogen and second nitrogen are bonded together by a bond group and having 8 to 50 atoms forming the cyclic structure: (wherein Q is bivalent to tetravalent bond group which is an aliphatic group, alicyclic group, aromatic group, or a combination of these groups and may contain a hetero atom or substituent); and/or (b) a polyvalent amine-based curing agent (component b) represented by the following formula (b-i): (wherein Ar 1 to Ar 4 are each independently a phenylene group or naphthalene-diyl group which may be substituted by a substituent).

1 . A thermosetting resin composition comprising:
 (A) an epoxy resin (component A); and   (B) a cyclic carbodiimide compound (component B) including a cyclic structure having one carbodiimide group and represented by the following formula (B-i) in which first nitrogen and second nitrogen are bonded together by a bond group and having 8 to 50 atoms forming the cyclic structure:   
       
         
           
           
               
               
           
         
         (wherein Q is bivalent to tetravalent bond group which is an aliphatic group, alicyclic group, aromatic group or a combination of these groups, and may contain a hetero atom or substituent); and/or 
         (b) a polyvalent amine-based curing agent (component b) represented by the following formula (b-i): 
       
       
         
           
           
               
               
           
         
         (wherein Ar 1  to Ar 4  are each independently a phenylene group or naphthalene-diyl group which may be substituted by a substituent). 
       
     
     
         2 . The thermosetting resin composition according to claim  1 , comprising:
 (A) an epoxy resin (component A); and   (B) a cyclic carbodiimide compound (component B) including a cyclic structure having one carbodiimide group and represented by the following formula (B-i) in which first nitrogen and second nitrogen are bonded together by a bond group and having 8 to 50 atoms forming the cyclic structure:   
       
         
           
           
               
               
           
         
         (wherein Q is bivalent to tetravalent bond group which is an aliphatic group, alicyclic group, aromatic group, or a combination of these groups, and may contain a hetero atom or substituent). 
       
     
     
         3 . The thermosetting resin composition according to  claim 2 , wherein the component B is a polyvalent cyclic carbodiimide compound having at least two carbodiimide groups in one molecule. 
     
     
         4 . The thermosetting resin composition according to  claim 2 , wherein the component B is a compound represented by the following formula (B-ii): 
       
         
           
           
               
               
           
         
         (wherein X is a tetravalent group represented by the following formula (B-iii). Ar 1  to Ar 4  are each independently an orthophenylene group or 1,2-naphthalene-diyl group which may be substituted by an alkyl group having 1 to 6 carbon atoms or phenyl group). 
       
       
         
           
           
               
               
           
         
       
     
     
         5 . The thermosetting resin composition according to  claim 2 , wherein the content of the cyclic carbodiimide compound (component B) is 0.01 to 50 parts by weight based on 100 parts by weight of the epoxy resin (component A). 
     
     
         6 . The thermosetting resin composition according to  claim 2 , wherein the glass transition temperature of a cured resin is 2° C. or more higher than the glass transition temperature of a cured resin obtained by curing a thermosetting resin composition comprising no component B under the same conditions. 
     
     
         7 . The thermosetting resin composition according to  claim 2 , further comprising a curing agent (component C). 
     
     
         8 . The thermosetting resin composition according to  claim 2 , further comprising a curing accelerator (component D). 
     
     
         9 . A process for producing a cured resin, comprising the step of heating the thermosetting resin composition of  claim 1 . 
     
     
         10 . A method of using a cyclic carbodiimide compound (component B) including a cyclic structure having one carbodiimide group and represented by the following formula (B-i) in which first nitrogen and second nitrogen are bonded together by a bond group and having 8 to 50 atoms forming the cyclic structure as a curing agent for an epoxy resin (component A): 
       
         
           
           
               
               
           
         
         (wherein Q is bivalent to tetravalent bond group which is an aliphatic group, alicyclic group, aromatic group, or a combination of these groups, and may contain a hetero atom or substituent). 
       
     
     
         11 . A method of using a cyclic carbodiimide compound (component B) including a cyclic structure having one carbodiimide group and represented by the following formula (B-i) in which first nitrogen and second nitrogen are bonded together by a bond group and having 8 to 50 atoms forming the cyclic structure as a curing accelerator for an epoxy resin (component A): 
       
         
           
           
               
               
           
         
         (wherein Q is bivalent to tetravalent bond group which is an aliphatic group, alicyclic group, aromatic group, or a combination of these groups and may contain a hetero atom or substituent). 
       
     
     
         12 . The thermosetting resin composition according to  claim 1 , comprising:
 (A) an epoxy resin (component A); and   (b) a polyvalent amine-based curing agent (component b) represented by the following formula (b-i):   
       
         
           
           
               
               
           
         
         (wherein Ar 1  to Ar 4  are each independently a phenylene group or naphthalene-diyl group which may be substituted by a substituent). 
       
     
     
         13 . The thermosetting resin composition according to  claim 12 , comprising 10 to 50 parts by weight of the polyvalent amine-based curing agent (component b) based on 100 parts by weight of the epoxy resin (component A). 
     
     
         14 . The thermosetting resin composition according to  claim 12 , comprising 10 to 45 parts by weight of the polyvalent amine-based curing agent (component b) based on 100 parts by weight of the epoxy resin (component A). 
     
     
         15 . The thermosetting resin composition according to  claim 12 , wherein the difference between the glass transition temperature (Tg·2H) of a cured resin after 2 hours of curing and the glass transition temperature (Tg·4H) of a cured resin after 4 hours of curing is less than 10° C. at a thermal curing temperature of 160° C. to 200° C. 
     
     
         16 . The thermosetting resin composition according to  claim 12 , wherein the glass transition temperature (Tg·160° C./4H) of a cured resin obtained after 4 hours of curing at a thermal curing temperature of 160° C. is 175° C. or higher. 
     
     
         17 . The thermosetting resin composition according to claim  12 , wherein the glass transition temperature (Tg·180° C./2H) of a cured resin obtained after 2 hours of curing at a thermal curing temperature of 180° C. is 175° C. or higher. 
     
     
         18 . The thermosetting resin composition according to  claim 12 , wherein the epoxy resin (component A) is a bisphenol type epoxy resin. 
     
     
         19 . A cured resin comprising a compound represented by the following formula (b-ii): 
       
         
           
           
               
               
           
         
         (wherein Ar 1  to Ar 4  are each independently a phenylene group or naphthalene-diyl group which may be substituted by a substituent. W 1 , W 2 , X 1 , X 2 , Y 1 , Y 2 , and Z 2  are each independently selected from a hydrogen atom and group represented by the following formula (b-iii), with the proviso that at least two out of W 1 , W 2 , X 1 , X 2 , Y 1 , Y 2 , Z 1  and Z 2  are groups represented by the following formula (b-iii)) 
       
       
         
           
           
               
               
           
         
         (wherein the wavy part represents an epoxy resin residue). 
       
     
     
         20 . The cured resin according to  claim 19 , wherein the content of the compound represented by the formula (b-ii) is not less than 50 wt % based on the total weight. 
     
     
         21 . The cured resin according to  claim 19  which is obtained by curing a thermosetting resin composition comprising (A) an epoxy resin (component A) and (b) a polyvalent amine-based curing agent (component b) represented by the following formula (b-i): 
       
         
           
           
               
               
           
         
         (wherein Ar 1  to Ar 4  are each independently a phenylene group or naphthalene-diyl group which may be substituted by a substituent). 
       
     
     
         22 . The thermosetting resin composition according to  claim 1 , comprising an epoxy resin (component A), a cyclic carbodiimide compound (component B) and a polyvalent amine-based curing agent (component b).