Sizing agent coated carbon fiber, method for producing sizing agent coated carbon fiber, carbon fiber reinforced composite material, and method for producing carbon fiber reinforced composite material

Patent metadata

Field	Value
Publication number	US-11118022-B2
Application number	US-201615528711-A
Country	US
Kind code	B2
Filing date	Jan 13, 2016
Priority date	Mar 6, 2015
Publication date	Sep 14, 2021
Grant date	Sep 14, 2021

Abstract

Sizing agent coated carbon fibers obtained by coating carbon fibers with a sizing agent comprising at least one of (A) to (C) in a total amount of 80 mass % or more with respect to the whole sizing agent, the carbon fibers each having a surface layer which has a thickness of 10 nm or larger and has an oxygen content of 4% or higher with respect to all the elements, wherein when the sizing agent coated carbon fibers are subjected three times to a 10-minute ultrasonic treatment in an acetone solvent, then the amount of the remaining sizing agent is 0.1-0.25 parts by mass per 100 parts by mass of the sizing agent coated carbon fibers. (A) At least one polymer selected from the group consisting of polyimides, polyetherimides, and polysulfones (B) A compound having a terminal unsaturated group and a polar group in the molecule (C) A polyether-type aliphatic epoxy compound and/or a polyol-type aliphatic epoxy compound which each have an epoxy equivalent of 250 g/eq or less and have two or more epoxy groups in the molecule.

First claim

The invention claimed is:

1. A sizing agent coated carbon fiber comprising a carbon fiber coated with a sizing agent, wherein
the sizing agent coated carbon fiber has a volume-specific resistance of 300 Ωcm or more,
the carbon fiber is polyacrylonitrile-based,
upon subjecting the carbon fiber cross-section to energy-dispersive X-ray spectroscopy, a high oxygen concentration layer is detected wherein
the proportion of oxygen relative to the total of all elements is 4% or more in a thickness of 10 nm or more and 30 nm or less from the carbon fiber surface, and
the proportion of oxygen relative to the total of all elements is less than 4% below the high oxygen concentration layer,

the sizing agent contains (A) to (C) in a total amount of 80 mass % or more relative to the total amount of the sizing agent,
upon subjecting the sizing agent coated carbon fiber to a 10-minute ultrasonic treatment in an acetone solvent three times, the amount of non-eluted sizing agent remaining on the carbon fiber is 0.1 parts by mass or more and 0.25 parts by mass or less per 100 parts by mass of the sizing agent coated carbon fiber, wherein (A), (B) and (C) are as follows:
(A) at least one member selected from the group consisting of polyimide, polyetherimide, and polysulfone,
(B) a compound having a terminal unsaturated group and a polar group in a molecule, and
(C) a polyether-type aliphatic epoxy compound and/or polyol-type aliphatic epoxy compound having an epoxy equivalent of 250 g/eq. or less and having two or more epoxy groups in a molecule, and
wherein the ratio (β)/(α) between the following (α) and (β) is 0.8 or more as determined by X-ray photoelectron spectroscopy using AlKα 1,2 :
(α): surface oxygen concentration (O/C) that is the ratio of the number of atoms of oxygen (O) to that of carbon (C) on the carbon fiber surface measured at a photoelectron take-off angle of 10°, and
(β): surface oxygen concentration (O/C) that is the ratio of the number of atoms of oxygen (O) to that of carbon (C) on the carbon fiber surface measured at a photoelectron take-off angle of 90°.

2. The sizing agent coated carbon fiber according to claim 1 , wherein the polyether-type aliphatic epoxy compound and/or polyol-type aliphatic epoxy compound (C) is a glycidyl-ether-type epoxy compound obtained by the reaction of at least one member selected from the group consisting of glycerol, diglycerol, polyglycerol, trimethylolpropane, pentaerythritol, sorbitol, and arabitol with epichlorohydrin.

3. The sizing agent coated carbon fiber according to claim 1 , wherein the sizing agent coated carbon fiber has a single-yarn fineness of 0.5 dtex or less.

4. The sizing agent coated carbon fiber according to claim 1 , wherein the twist of the sizing agent coated carbon fiber is not more than 1 turn meter.

5. A method for producing a sizing agent coated carbon fiber according to claim 1 , wherein the method comprises coating a carbon fiber with a sizing agent, followed by a heat treatment at 240° C. or more for 60 to 3,000 seconds.

6. The method for producing a sizing agent coated carbon fiber according to claim 5 , wherein the carbon fiber is subjected to liquid-phase electrolytic oxidation at a current density of 5 A/m 2 or less.

7. The method for producing a sizing agent coated carbon fiber according to claim 6 , wherein the liquid-phase electrolytic oxidation is performed at 40° C. or more.

8. A prepreg obtainable by impregnating the sizing agent coated carbon fiber according to claim 1 with a thermosetting resin.

9. A carbon fiber reinforced composite material obtainable by curing the prepreg according to claim 8 .

10. A carbon fiber reinforced resin composition comprising:
the sizing agent coated carbon fiber according to claim 1 ; and
a matrix resin including a thermoplastic resin or a radically polymerizable resin.

11. The carbon fiber reinforced resin composition according to claim 10 , wherein the matrix resin is at least one member selected from a polyimide resin, a polyetherimide resin, a polyarylene sulfide resin, a polycarbonate resin, a polyolefin resin, and a polyamide resin.

12. A method for producing a carbon fiber reinforced resin composition, comprising:
a step of producing a sizing agent coated carbon fiber by the method according to claim 5 ; and
a step of blending the sizing agent coated carbon fiber with a matrix resin.

13. A carbon fiber reinforced resin composition, comprising the carbon fiber reinforced resin composition according to claim 10 and being a molding material in any one of the following forms (D), (E), (F), and (G):
molding material (D): a columnar molding material, in which the carbon fiber is arranged such that the difference in angle between the axial direction thereof and the major axis line of the molding material is 20° or less, the content of carbon fiber having a length of 50% or less of the length of the molding material is 30 mass % or less, and the average two-dimensional orientation angle defined by a single fiber of the carbon fiber forming the molding material and another single fiber of the carbon fiber closest thereto is 10 to 80°,
molding material (E): a molding material, in which the carbon fiber is in the form of a single fiber and substantially two-dimensionally oriented,
molding material (F): a molding material in which the carbon fiber is in the form of a bundle and substantially two-dimensionally oriented,
molding material (G): a prepreg.

14. The carbon fiber reinforced resin molded article obtainable by molding the carbon fiber reinforced resin composition according to claim 13 .

15. A laminated prepreg comprising:
at least two plies of a carbon fiber layer (b) containing a sizing agent coated carbon fiber (a); and
a layer of a polymer resin (c) disposed between the two plies,
the laminated prepreg being configured such that
(i) the sizing agent coated carbon fiber (a) is the sizing agent coated carbon fiber according to claim 1 , and
(ii) a composite material having an interlayer structure obtainable by solidifying the laminated prepreg has a volume-specific resistance of 500 Ω·m or more in the thickness direction of the laminated prepreg.

16. The laminated prepreg according to claim 15 , wherein the ratio T1/T2 between the average thickness T1 of the carbon fiber layer (b) and the average thickness T2 of the layer of a polymer resin (c) in the composite material is 9 or less.

17. The laminated prepreg according to claim 15 , wherein the layer of a polymer resin (c) contains a thermosetting resin and a curing agent in a total amount 50 parts by mass or more per 100 parts by mass of the polymer resin in the layer.

18. The laminated prepreg according to claim 15 , wherein the layer of a polymer resin (c) contains at least one thermoplastic resin selected from the group consisting of particles, fibers, and a film of a thermoplastic resin.

19. The laminated prepreg according to claim 18 , wherein the thermoplastic resin is contained in an amount of 5 to 30 mass % or more relative to the total amount of the polymer resin contained in the laminated prepreg.

20. The laminated prepreg according to claim 15 , wherein the carbon fiber volume fraction in the composite material is 60 to 70%.

21. A method for producing a laminated prepreg, being a method for producing the laminated prepreg according to claim 15 , wherein the sizing agent coated carbon fiber (a) is obtained through a step of coating a carbon fiber with a sizing agent, followed by a heat treatmen

Assignees

• Toray Industries

Inventors

• Ichikawa Tomoko
• Yoshihiro Kazuki
• Mizuta Hisafumi
• Endo Makoto

Classifications

• C08J5/249

  characterised by the additives used in the prepolymer mixture · CPC title

• C08J5/248

  using pre-treated fibres · CPC title

• D06M13/11 Primary

  Compounds containing epoxy groups or precursors thereof · CPC title

• C08J5/06 Primary

  using pretreated fibrous materials · CPC title

• D01F9/12

  Carbon filaments; Apparatus specially adapted for the manufacture thereof · CPC title