Uncured laminate, reinforcing fiber composite material, method for producing uncured laminate, and method for producing reinforcing fiber composite material

1. An uncured layered plate comprises: a plurality of layers fused together, the plurality of layers each comprising reinforcement fibers and a powder of an imide oligomer represented by formula (1):

wherein:

R1 represents a divalent residue of at least one aromatic diamine selected from 2-phenyl-4,4′-diaminodiphenylether, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-(4-aminophenoxy)phenyl)fluorene, 1,3-diaminobenzene, and 4-phenoxy-1,3-diaminobenzene;

R2 represents a divalent residue of at least one aromatic diamine selected from 9,9-bis(4-aminophenyl)fluorene, 1,3-9,9-bis(4-(4-aminophenoxy)phenyl)fluorene, diaminobenzene, and 4-phenoxy-1,3-diaminobenzene;

R3 and R4, which are identical to each other or different from each other, each represents a tetravalent residue of an aromatic tetracarboxylic acid;

one of R5 and R6 represents a phenyl group, and the other one of R5 and R6 represents a hydrogen atom;

m and n satisfy the following:

1 ≤m,

0 ≤n ≤5,

1 ≤ m+n≤ 10, and

0.5≤ m/(m+n)≤ 1; and

a sequence of repeating units may be a block sequence or a random sequence.

2. The uncured layered plate according to claim 1 , wherein the imide oligomer is represented by formula (2):

wherein:

R1 represents a divalent residue of an aromatic diamine selected from 2-phenyl-4,4′-diaminodiphenylether and 4-phenoxy-1,3-diaminobenzene;

one of R2 and R3 represents a phenoxy group, and the other one of R2 and R3 represents a hydrogen atom;

R4 and R5, which are identical to each other or different from each other, each represent a tetravalent residue of an aromatic tetracarboxylic acid;

one of R6 and R7 represents a phenyl group, and the other one of R6 and R7 represents a hydrogen atom;

m and n satisfy the following:

1≤ m,

0≤ n≤ 5,

1≤ m+n≤ 10, and

0.5≤ m /( m+n )≤1; and

a sequence of repeating units may be a block sequence or a random sequence.

3. The uncured layered plate according to claim 1 , wherein a volatile component is less than 20 wt % with respect to the imide oligomer.

4. A method for producing a reinforcing fiber composite material, the method comprising:

mixing the powder of the imide oligomer with reinforcement fibers to obtain each of the plurality of layers;

stacking the plurality of layers to form one layered plate; and

heat-curing at least two layered plates, at least one of the at least two layered plates is the uncured layered plate recited in claim 1 .

5. The method according to claim 4 , wherein the at least two layered plates include two or more uncured layered plates.

6. The method according to claim 4 , wherein the at least two layered plates include at least the one uncured layered plate and at least one layered plate which is not the uncured layered plate.

7. The method according to claim 4 , wherein heat-curing is carried out at a processing temperature (T 4 ) of not lower than 340° C. and not higher than 400° C.

8. A method for producing an uncured layered plate, the method comprising:

mixing a powder of an imide oligomer with reinforcement fibers to obtain a layer;

stacking a plurality of the layers; and

heating at a temperature at which the plurality of the layers after stacking are fused together but are not completely cured.

9. The method according to claim 8 , wherein heating is carried out at a temperature (T 3 ) which is higher than a glass transition temperature (T 1 ) of the imide oligomer and which is lower than a curing temperature (T 2 ) of the imide oligomer.

10. The method according to claim 8 , wherein the imide oligomer has a terminal capped with 4-phenylethynyl phthalic anhydride.

11. A method for producing a reinforcing fiber composite material, the method comprising:

(a) producing uncured layered plates each by (a-1) stacking a plurality of layers each of which is obtained by causing a powder of an imide oligomer to adhere to reinforcement fibers and then (a-2) heating at a temperature at which the plurality of layers fuse together but are not cured;

(b) obtaining a layered body by (b-1) stacking the uncured layered plates obtained in the step (a) and then (b-2) keeping the layered body at 260° C. to 340° C. and 0.1 MPa to 20 MPa for 5 minutes to 300 minutes; and

(c) further keeping the layered body at 330° C. to 500° C. and 0.1 MPa to 20 MPa for 15 minutes to 120 minutes.

12. The method according to claim 11 , further comprising, before the step (a), opening a fiber bundle of the reinforcement fibers.

13. The method according to claim 11 , wherein the imide oligomer is represented by formula (1):

wherein:

R 1 represents a divalent residue of at least one aromatic diamine selected from 2-phenyl-4,4′-diaminodiphenylether, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-(4-aminophenoxy)phenyl)fluorene, 1,3-diaminobenzene, and 4-phenoxy-1,3-diaminobenzene;

R 2 represents a divalent residue of at least one aromatic diamine selected from 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-(4-aminophenoxy)phenyl)fluorene, 1,3-diaminobenzene, and 4-phenoxy-1,3-diaminobenzene;

R 3 and R 4 , which are identical to each other or different from each other, each represent a tetravalent residue of an aromatic tetracarboxylic acid;

one of R 5 and R 6 represents a phenyl group, and the other one of R 5 and R 6 represents a hydrogen atom;

m and n satisfy the following:

1≤ m,

0≤ n≤ 5,

1 ≤ m+n≤ 10, and

0.5≤ m /( m+n )≤1; and

a sequence of repeating units may be a block sequence or a random sequence.