Prepreg and carbon fiber-reinforced composite material

Patent metadata

Field	Value
Publication number	US-11286359-B2
Application number	US-201916533517-A
Country	US
Kind code	B2
Filing date	Aug 6, 2019
Priority date	Jul 25, 2012
Publication date	Mar 29, 2022
Grant date	Mar 29, 2022

Abstract

A prepreg includes; sizing agent-coated carbon fibers coated with a sizing agent; and a thermosetting resin composition impregnated into the sizing agent-coated carbon fibers. The sizing agent includes an aliphatic epoxy compound (A) and an aromatic compound (B) at least containing an aromatic epoxy compound (B1). The thermosetting resin composition includes a thermosetting resin (D) and a latent hardener (E), and optionally includes an additive (F) other than the thermosetting resin (D) and the latent hardener (E). The (a)/(b) ratio is within a predetermined range where (a) is the height of a component at a binding energy assigned to CHx, C—C, and C═C and (b) is the height of a component at a binding energy assigned to C—O in a C1s core spectrum of the surfaces of the sizing agent-coated carbon fibers analyzed by X-ray photoelectron spectroscopy.

First claim

The invention claimed is:

1. A prepreg comprising:
sizing agent-coated carbon fiber bundles coated with a sizing agent; and
a thermosetting resin composition impregnated into the sizing agent-coated carbon fiber bundles, wherein
the sizing agent includes an aliphatic epoxy compound (A) and an aromatic compound (B) at least containing an aromatic epoxy compound (B1),
the sizing agent-coated carbon fiber bundles have an (a)/(b) ratio of 0.50 to 0.90 where (a) is a height (cps) of a component at a binding energy (284.6 eV) assigned to CHx, C-C, and C═C and (b) is a height (cps) of a component at a binding energy (286.1 eV) assigned to C-O in a C 1s core spectrum of a surface of the sizing agent applied onto the carbon fiber bundles analyzed by X-ray photoelectron spectroscopy using AlKα 1,2 as an X-ray source at a photoelectron takeoff angle of 15°, and
the thermosetting resin composition includes a thermosetting resin (D) and a latent hardener (E),
the thermosetting resin composition is an epoxy resin composition at least containing an epoxy resin (D1) as the thermosetting resin (D) and a compound (E1) of Formula (2):

wherein in Formula (2), R 4 to R 7 are at least one selected from the group consisting of a hydrogen atom, C 1-4 aliphatic hydrocarbon groups, alicyclic hydrocarbon groups having a carbon number of 4 or less, and halogen atoms; and X is one selected from —O—, —S—, —CO—, —C(═O)O—, and —C(═O)NH—) as the latent hardener (E);
the sizing agent and the compound (E1) of General Formula (2) are used in a combination wherein when the sizing agent and the compound (E1) are mixed in an amine equivalent/epoxy equivalent ratio of 0.9 to form a mixture and the mixture is stored in an atmosphere of 25° C. and 60% RH for 20 days, the mixture has an increase in glass transition point by 25° C. or smaller; and
the mass ratio (A)/(B1) of the aliphatic epoxy compound (A) and the aromatic epoxy compound (B1) is 52/48 to 80/20.

2. The prepreg according to claim 1 , wherein the sizing agent has an epoxy equivalent of 350 to 550 g/eq.

3. The prepreg according to claim 1 , wherein the sizing agent contains at least the aliphatic epoxy compound (A) in an amount of 35 to 65% by mass and the aromatic compound (B) in an amount of 35 to 60% by mass relative to a total amount of the sizing agent except solvents.

4. The prepreg according to claim 1 , wherein the aliphatic epoxy compound (A) and the aromatic epoxy compound (B1) are contained in a mass ratio of 52/48 to 80/20.

5. The prepreg according to claim 1 , wherein the aliphatic epoxy compound (A) is a polyether polyepoxy compound and/or a polyol polyepoxy compound having two or more epoxy groups in a molecule.

6. The prepreg according to claim 5 , wherein the aliphatic epoxy compound (A) is a glycidyl ether epoxy compound obtained by reaction of epichlorohydrin with a compound selected from ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, polybutylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, glycerol, diglycerol, polyglycerol, trimethylolpropane, pentaerythritol, sorbitol, and arabitol.

7. The prepreg according to claim 1 , wherein the aromatic epoxy compound (B1) is a bisphenol A epoxy compound or a bisphenol F epoxy compound.

8. The prepreg according to claim 1 , wherein the sizing agent contains an ester compound (C) having no epoxy group in a molecule in an amount of 2 to 35% by mass relative to a total amount of the sizing agent except solvents.

9. The prepreg according to claim 1 , wherein the sizing agent-coated carbon fibers satisfy relation (III):
0.50≤( I )≤0.90 and 0.60<( II )/( I )<1.0  (III)

where (I) is a value of (a)/(b) of surfaces of the sizing agent-coated carbon fibers before ultrasonication, (II) is a value of (a)/(b) of the surfaces of the sizing agent-coated carbon fibers where an adhesion amount of the sizing agent is reduced to 0.09 to 0.20% by mass by ultrasonic cleaning of the sizing agent-coated carbon fibers in an acetone solvent, (a) is the height (cps) of a component at a binding energy (284.6 eV) assigned to CHx, C—C, and C═C, and (b) is the height (cps) of a component at a binding energy (286.1 eV) assigned to C—O in a C 1s core spectrum of the sizing agent-coated carbon fibers analyzed by X-ray photoelectron spectroscopy using an X-ray at 400 eV at a photoelectron takeoff angle of 55°.

10. The prepreg according to claim 1 , wherein X is —O— in the compound (E1) of Formula (2).

11. The prepreg according to claim 1 , wherein at least one of the amino groups is present at a meta-position in the compound (E1) of Formula (2).

12. The prepreg according to claim 1 , wherein the epoxy resin (D1) contains an epoxy resin (D11) having two or more ring structures that are four- or more-membered rings and having one or two amine glycidyl groups or ether glycidyl groups that are directly bonded to the ring structure and contains an epoxy resin (D12) having three or more functional groups.

13. The prepreg according to claim 12 , wherein the epoxy resin (D12) has a structure of Formula (4):

wherein in Formula (4), R 10 to R 13 are at least one selected from the group consisting of a hydrogen atom, C 1-4 aliphatic hydrocarbon groups, alicyclic hydrocarbon groups having a carbon number of 4 or less, and halogen atoms; and Y is one selected from —CH 2 —, —O—, —S—, —CO—, —C(═O)O—, —SO 2 —, and —C(═O)NH—.

14. The prepreg according to claim 13 , wherein Y is —CH 2 — or —O— in Formula (4) for the epoxy resin (D12).

15. The prepreg according to claim 13 , wherein at least one of the diglycidyl amino groups is present at a meta-position in Formula (4) for the epoxy resin (D12).

16. A carbon fiber-reinforced composite material produced by molding the prepreg according to claim 1 .

Assignees

• Toray Industries

Inventors

• Arai Nobuyuki
• Ichikawa Tomoko
• Taiko Hiroshi
• Endo Makoto
• Kobayashi Masanobu
• Misumi Jun

Classifications

• C08G59/38 Primary

  together with di-epoxy compounds · CPC title

• C08J5/248

  using pre-treated fibres · CPC title

• D06M2101/40

  Fibres of carbon · CPC title

• D06M13/11

  Compounds containing epoxy groups or precursors thereof · CPC title

• C08K5/1515

  Three-membered rings · CPC title