Polyamic acid having specific composition, varnish, cured product, and composite material

Abstract

The present invention provides an amide acid oligomer which has specific composition and which is capable of providing a cured product having excellent physical properties, in particular, an excellent glass transition temperature, etc.

1 . An amide acid oligomer represented by the following formula (1): 
       
         
           
           
               
               
           
         
         where: 
         (I) n is an integer satisfying 1≤n≤100; 
         (II) Q represents a tetravalent residue derived from an aromatic tetracarboxylic acid (A), and contains a structural unit represented by the following general formula (2) and a structural unit represented by the following general formula (3) at a molar ratio of 100/0 to 20/80: 
       
       
         
           
           
               
               
           
         
         (III) Y represents a divalent residue derived from an aromatic diamine (B), and contains a structural unit represented by the following general formula (4) and a structural unit represented by the following general formula (5) at a molar ratio of 100/0 to 20/80: 
       
       
         
           
           
               
               
           
         
         where in formula (4), X 1  represents a direct bond or a divalent linking group selected from the group consisting of an ether group, a carbonyl group, a sulfonyl group, a sulfide group, an amide group, an ester group, an isopropylidene group, an isopropylidene hexafluoride group, and 9,9-fluorenylidene group, and 
         (i) one of R 1  to R 5  represents one selected from the group consisting of an aryl group and a halogenated aryl group, another one of R 1  to R 5  represents a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, the other three of R 1  to R 5  each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, one of R 6  to R 10  represents a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, and the other four of R 6  to R 10  each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group 
         or 
         (ii) one of R 1  to R 5  represents a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, the other four of R 1  to R 5  each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, one of R 6  to R 10  represents one selected from the group consisting of an aryl group and a halogenated aryl group, another one of R 6  to R 10  represents a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, and the other three of R 6  to R 10  each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group; and 
         (IV) not less than 85 mol % and not more than 100 mol % of molecular terminals Z have structures each represented by the following formula (6) or (7), not more than 15 mol % and not less than 0 mol % of the molecular terminals Z are amine terminals each derived from an aromatic diamine component which is a raw material of the amide acid oligomer, not less than 50 mol % and not more than 100 mol % of the structures each represented by formula (6) or (7) are represented by formula (6), and not less than 0 mol % and less than 50 mol % of the structures each represented by formula (6) or (7) are represented by formula (7): 
       
       
         
           
           
               
               
           
         
       
     
     
         2 . The amide acid oligomer as set forth in  claim 1 , wherein:
 the amide acid oligomer is capable of being dissolved at a solid content concentration of not less than 20 weight % at room temperature in a solvent;   the solvent is selected from the group consisting of a mixed solvent of an alcohol-based solvent and an ether-based solvent, a single solvent of a hydroxy ether-based solvent, a mixed solvent of an alcohol-based solvent and a hydroxy ether-based solvent, a mixed solvent of an ether-based solvent and a hydroxy ether-based solvent, and a mixed solvent of an alcohol-based solvent, an ether-based solvent, and a hydroxy ether-based solvent; and   the solvent has a boiling point (a boiling point of each single solvent, in a case where the solvent is a mixed solvent) of not higher than 130° C.   
     
     
         3 . The amide acid oligomer as set forth in  claim 1 , wherein:
 the amide acid oligomer is capable of being dissolved at a solid content concentration of not less than 20 weight % at room temperature in a solvent;   the solvent is selected from the group consisting of a single solvent of a hydroxy ether-based solvent and a mixed solvent of an ether-based solvent and a hydroxy ether-based solvent; and   the solvent has a boiling point (a boiling point of each single solvent, in a case where the solvent is a mixed solvent) of not higher than 130° C.   
     
     
         4 . A varnish obtained by dissolving, in a solvent, the amide acid oligomer recited in  claim 1 . 
     
     
         5 . An imide oligomer obtained from the amide acid oligomer recited in  claim 1 . 
     
     
         6 . A cured product obtained by heat-curing the amide acid oligomer recited in  claim 1 . 
     
     
         7 . A cured product obtained by heat-curing a varnish recited in  claim 4 . 
     
     
         8 . A film obtained from the amide acid oligomer recited in  claim 1 . 
     
     
         9 . A prepreg or semipreg obtained by heat-fusing reinforcement fibers and the amide acid oligomer recited in  claim 1  together or by impregnating the reinforcement fibers with the amide acid oligomer. 
     
     
         10 . A fiber-reinforced composite material obtained by heat-curing a prepreg or semipreg recited in  claim 9 .