Thermosetting resin composition, prepreg, fiber-reinforced plastic molded body and method for producing same

Patent metadata

Field	Value
Publication number	US-11292874-B2
Application number	US-201916281298-A
Country	US
Kind code	B2
Filing date	Feb 21, 2019
Priority date	Aug 29, 2016
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

Abstract

Provided is a thermosetting resin composition (C) of which curing can be started at a relatively low temperature in a short time and a cured product exhibits high heat resistance, the thermosetting resin composition (C) comprising an epoxy resin; an epoxy resin curing agent; and an epoxy resin curing accelerator, wherein the epoxy resin curing agent contains an imidazole-based curing agent 1 which is not encapsulated in a microcapsule and a curing agent 2 which is encapsulated in a microcapsule, and the epoxy resin curing accelerator comprises a urea derivative.

First claim

The invention claimed is:

1. A film, comprising:
a reinforcing fiber substrate; and
a thermosetting resin composition, comprising:
an epoxy resin;
an epoxy resin curing agent; and
an epoxy resin curing accelerator comprising a urea derivative,
wherein the epoxy resin curing agent comprises a first curing agent which is an imidazole-based curing agent, not being encapsulated in a microcapsule, and a second curing agent, which is encapsulated in a microcapsule,
wherein the reinforcing fiber substrate has a fiber aerial weight of 50 g/m 2 or less, and
wherein the thermosetting resin composition is present in a higher areal weight content than the reinforcing fiber substrate in the film.

2. The film of claim 1 , wherein the imidazole-based curing agent of the first curing agent is a compound of formula (1)

wherein R 1 is an optionally substituted linear or branched alkyl group comprising from 1 to 5 carbon atoms, an optionally substituted phenyl group, H, or a hydroxymethyl group, and R 2 is a linear or branched alkyl group having from 1 to 5 carbon atoms, an optionally substituted phenyl group, or H, and
wherein the second curing agent is a compound of formula (2):

wherein R 3 is an organic group comprising a carbon atom and R 4 to R 6 are independently H, a methyl group, or an ethyl group.

3. The film of claim 1 , wherein the imidazole-based curing agent of the first curing agent is a compound of formula (1):

wherein
R 1 is an optionally substituted linear or branched alkyl group comprising from 1 to 5 carbon atoms, an optionally substituted phenyl group, H, or a hydroxymethyl group, and
R 2 is a linear or branched alkyl group having from 1 to 5 carbon atoms, an optionally substituted phenyl group, or H.

4. The film of claim 1 , wherein the urea derivative comprises 3-phenyl-1,1-dimethylurea or 2,4-bis(3,3-dimethylureido)toluene.

5. The film of claim 1 , wherein the first curing agent comprises 2-phenyl-4,5-dihydroxymethylimidazole or 2-phenyl-4-methyl-5-hydroxymethylimidazole.

6. The film of claim 1 , wherein the second curing agent has a formula (2):

wherein
R 3 is an organic group comprising a carbon atom, and
R 4 to R 6 are independently H, a methyl group, or an ethyl group.

7. The film of claim 1 , wherein the epoxy resin comprises an epoxy resin having a structure unit of formula (3):

8. The film of claim 1 , wherein the epoxy resin comprises a bisphenol A type epoxy resin.

9. The film of claim 1 , wherein, in mass percent,
the first curing agent is present in a range of from 5 to 15%,
the second curing agent is present in a range of from 1 to 3%, and
the urea derivative is present in a range of from 2 to 5%,
in the thermosetting resin composition.

10. The film of claim 1 , wherein the thermosetting resin composition has a lowest viscosity at from 80° C. to 98° C. in temperature-programmed viscosity measurement to be conducted under conditions of an initial temperature of 30° C. and a rate of temperature increase of 2.0° C./min, and
wherein the thermosetting resin composition has a glass transition temperature of a cured product obtained by heating the thermosetting resin composition at 140° C. for 5 minutes attained by dynamic viscoelasticity measurement of 150° C. or higher.

11. The film of claim 1 , wherein the reinforcing fiber substrate comprises glass fiber.

12. The film of claim 1 , wherein the reinforcing fiber substrate comprises carbon fiber.

13. The film of claim 1 , wherein the reinforcing fiber substrate is a nonwoven fabric.

14. The film of claim 1 , wherein the content of the thermosetting resin composition is in a range of from 30 to 150 g/m 2 .

15. A method for producing a fiber-reinforced plastic molded body, the method comprising:
preparing a laminate comprising the resin film of claim 1 and a plurality of sheet-like prepreg substrates such that the resin film is arranged on one surface of the laminate; and
subjecting the laminate to a heat and pressure treatment using a mold.

16. The method of claim 15 , further comprising:
shaping the laminate into a preform before subjecting the laminate to the heat and pressure treatment.

17. The film of claim 1 , wherein a fiber length of a reinforcing fiber in the film is in a range of from 5 to 50 mm.

18. The film of claim 1 , having a thickness in a range of from 20 to 400 μm.

Assignees

• Mitsubishi Chem Corp

Inventors

• Teranishi Takuya
• Ichino Masahiro
• Ikeda Kazuhisa
• Oota Akira

Classifications

• C08L63/04

  Epoxynovolacs · CPC title

• C08L63/00 Primary

  Compositions of epoxy resins; Compositions of derivatives of epoxy resins · CPC title

• C08K7/14

  Glass · CPC title

• C08K7/06

  Elements · CPC title

• C08J2363/04

  Epoxynovolacs · CPC title