US 12,030,999 B2
Method for producing fiber-reinforced composite material
Yuuki Sato, Kanagawa (JP); Kousuke Ikeuchi, Kanagawa (JP); and Nobuhiko Matsumoto, Kanagawa (JP)
Assigned to MITSUBISHI GAS CHEMICAL COMPANY, INC., Chiyoda-ku (JP)
Appl. No. 17/904,344
Filed by MITSUBISHI GAS CHEMICAL COMPANY, INC., Chiyoda-ku (JP)
PCT Filed Apr. 14, 2021, PCT No. PCT/JP2021/015394
§ 371(c)(1), (2) Date Aug. 16, 2022,
PCT Pub. No. WO2021/229985, PCT Pub. Date Nov. 18, 2021.
Claims priority of application No. 2020-085887 (JP), filed on May 15, 2020.
Prior Publication US 2023/0066520 A1, Mar. 2, 2023
Int. Cl. C08J 5/04 (2006.01)
CPC C08J 5/042 (2013.01) [C08J 2333/24 (2013.01)] 9 Claims
 
1. A method for producing a fiber-reinforced composite material comprising a polyimide resin (A) and a continuous reinforcing fiber (B), wherein
the polyimide resin (A) comprises a repeating structural unit represented by the following formula (1) and a repeating structural unit represented by the following formula (2), and
a content ratio of the repeating structural unit of the formula (1) with respect to the total of the repeating structural unit of the formula (1) and the repeating structural unit of the formula (2) is from 20 mol % to less than 40 mol %:

OG Complex Work Unit Chemistry
wherein R1 represents a divalent group having from 6 to 22 carbon atoms comprising at least one alicyclic hydrocarbon structure; R2 represents a divalent chain aliphatic group having from 5 to 16 carbon atoms; and X1 and X2 each independently represent a tetravalent group having from 6 to 22 carbon atoms comprising at least one aromatic ring,
the method comprising the following (I) and (II) in that order:
(I) laminating at least one polyimide resin (A) layer and at least one continuous reinforcing fiber (B) layer to obtain a laminated product; and
(II) molding the laminated product by heating and pressurizing under a condition where a working parameter X expressed by the following expression (1) is from 56.8 to 73.3:
X=(Tp−Tm)3×P1/2/1000  (i),
wherein Tp represents a temperature (° C.) during the molding, Tm represents a melting point (° C.) of the polyimide resin (A), and P represents a press pressure (MPa) during the molding, and wherein Tp−Tm in the expression (i) is from 25° C. to 40° C.,
wherein a resin outflow rate in heat and pressure molding in (II) is from 1.0% to 5.0%,
wherein the polyimide resin (A) layer used in (I) is a layer composed of a film or fibers of the polyimide resin (A),
wherein, when the polyimide resin (A) layer is the film, a thickness of the film is from 20 to 500 μm, and
wherein, when the polyimide resin (A) layer is composed of the fibers of the polyimide resin (A), the polyimide resin (A) layer is produced by using a thermoplastic resin fiber bundle in which the fibers are bundled, and the total fineness per fiber bundle is from 37 to 600 D.