JPS6175879A - Sizing agent for carbon fiber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a sizing agent for carbon fibers, and more particularly to a sizing agent that facilitates handling of carbon fibers and improves the physical properties of the composite.

Carbon fiber is lightweight, has high strength and high modulus, and is therefore attracting attention as a reinforcing material for composites. However, since carbon fibers originally have low elongation and are brittle fibers, they easily become fuzzed or broken due to mechanical friction.

These fluffs and yarn breakage significantly reduce the handling properties of the carbon fibers and also reduce the physical properties of the composite. Therefore, a sizing agent is added to the carbon fibers, the sizing agent bundles the carbon fibers, gives the carbon fibers 7 flexibility, improves the wear resistance of the carbon fibers, and improves the abrasion resistance of the carbon fibers. Attempts have been made to improve the inherently poor adhesion between fibers and matrix resins to increase the interlaminar shear strength of the resulting composites.

The present invention relates to such a sizing agent. <Prior art and its problems> The following sizing agents for carbon fibers have been proposed using aromatic glycidyl ethers and aromatic glycidyl amines. There is.

First, there is a sizing agent using bisphenol A diglyphyl ether (Japanese Patent Publication No. 57-15229).

This uses a compound similar to that of the matrix resin in order to improve the adhesion between the carbon fiber and the matrix resin. Sizing agents of this type certainly improve the adhesion. However, when weaving carbon fibers, when the carbon fibers are required to have binding strength and especially flexibility, such performance is extremely insufficient, and the effect of suppressing the occurrence of fuzz and thread breakage during weaving is said to be low. There is a problem.

In addition, bisphenol A type epoxy resin (Epicote 8
There is a sizing agent that uses a mixture of 28 and Ebicor 1-1001 in a specific ratio (all manufactured by Shell) as an aqueous emulsion using a polyoxyethylene/ethylene nonionic surfactant as an emulsifier (JP-A-57 -1717
67). However, in this case, even if the type and amount of emulsifier used is specified, there is a problem that it is difficult to satisfy both the suppression of fuzz and thread breakage during weaving of carbon fibers and the interlaminar shear strength of the resulting composite. be.

There is also a sizing agent using N, N, N, N-tetraglycidylphenylenediamine (Japanese Patent Publication No. 59-9664). This improves the adhesion between the carbon fiber and the matrix resistor.

This type of sizing agent provides better adhesion between carbon fibers and matrix resin than the conventional sizing agent that uses bisphenol A diglyndyl ether, and improves the interlaminar shear strength of the resulting composite. However, since the sizing agent contains tertiary amine groups, the epoxy groups change over time, and as a result, the flexibility of carbon fibers treated with the sizing agent decreases over time.
There is a problem that the carbon fiber loses its properties and becomes hard, which increases fuzz and thread breakage during weaving of the carbon fiber.

In summary, conventionally proposed sizing agents for carbon fibers provide flexibility to carbon fibers, improve the abrasion resistance of carbon fibers, and suppress the occurrence of fuzz and yarn breakage during weaving of carbon fibers. There is no such thing that can fully demonstrate the effect and also exhibit the effect of improving the interlaminar shear strength of the composite obtained by improving the adhesion between carbon fiber and IJ sock resin.

<Problems to be solved by the invention> The present invention solves the conventional problems as described above.
It provides carbon fibers with sufficient binding strength and abrasion resistance, suppresses the occurrence of fuzz and thread breakage, greatly improves the handling properties of carbon fibers, and also improves the adhesion between carbon fibers and matrix resin. The present invention provides a sizing agent for carbon fibers that imparts excellent interlaminar shear strength to the resulting composite.

Means for Solving the Problems> However, as a result of intensive research from the above viewpoint, the present inventors discovered that a specific bisphenol type polycarbonate epoxy compound is correct and suitable, and have completed the present invention. It was.

That is, the present invention relates to a sizing agent for carbon fibers characterized by containing a bisphenol type polycarbonate epoxy compound represented by the following general formula (I) or (II).

General formula (I) 2 General formula (■): [However, R is -CH2CH20COCH2CH2- and/or ■ CH30CH3 In the case of a mixture, block bonding or random bonding Ha 0 CH30 -CHz-□ n is an integer from 1 to 30 OX is Residues selected from the following 1) or 11) (among these residues, -〇- is bonded to the terminal glycidyl group of the general formula (I[)) Or +) -o-p- or -〇- P- (Za is R'O- or Z3 Za υ is an alkyl group, alkenyl group or substituted phenyl group having 1 to 18 carbon atoms)] In the general formula (I) or (I), n is 1 to 10. Integers are preferred. This is because it has an excellent effect of suppressing the occurrence of fuzz and yarn breakage, and an effect of improving the interlayer shear strength of the resulting composite. Also, the general formula (I) or (
In II), it is more preferable that n is an integer of 1 to 10) and R is -CH2CH20COCH2CH2-. In this case, the general formula (I) or (
This is because the effects of the present invention are more pronounced, such as further improving the interlaminar shear strength of the composite obtained by adding the bisphenol type polycarbonate epoxy compound represented by n) to carbon fibers. The solvent for the type polycarbonate epoxy compound is preferably methyl ethyl ketone, acetone, dichloroethane, ethyl acetate, or a mixture thereof.
In addition to being used as a solution in such an organic solvent, it can also be used as an emulsion in which a nonionic surfactant is used as an emulsifier and dispersed in water.

The sizing agent according to the present invention has the general formula (I) or (
In addition to the bisphenol-type polycarbonate epoxy compound shown in II), conventional sizing agents, smoothing agents, surfactants, etc. can be contained as appropriate within a range that does not impair the effects of the present invention. Examples of these include sizing agents such as bisphenol A diglycidyl ether, novolac-type glycidyl ether, or epoxy compounds such as N, N, Ni N'-tetraglycidyldiaminodiphenylmethane, and smoothing agents such as stearyl There are fatty acid esters such as laurate, lauryl stearate or oleyl oleate.
Furthermore, as a surfactant, polyoxyethylene (6 mol) nonylphenyl ether or polyoxyethylene (3 mol)
0 mol) nonionic surfactants such as tribenzylated phenyl ethers. In either case, the sizing agent according to the present invention comprises a bisphenol type polycarbonate epoxy compound represented by the general formula (I) or (M),
It usually contains 10 parts by weight or more, preferably 50 parts by weight or more.

Effects, etc.> The sizing agent according to the present invention is applied to various carbon fibers (including graphite fibers) such as PAN-based, pitch-based, or rayon-based fibers, and exhibits the desired effects. The specific application method may be any conventional method such as a dipping method, a spray method, or a roller method, in which carbon fibers are impregnated with a sizing agent solution and then dried using an infrared lamp, hot air, or the like. Upon application, the sizing agent is made into an aqueous emulsion with an organic solvent solution or a small amount of emulsifier, and adjusted to usually 25% by weight or less, preferably 0.5 to 5% by weight in terms of the active ingredient. The amount of the sizing agent attached to the carbon fiber is usually 0.0% in terms of the active ingredient.
It has a weight of 2 to 6, preferably 0.3 to 2.

<Effects of the Invention> As explained above, the present invention has the following effects in summary.

(I) Since carbon fibers can be endowed with excellent cohesive strength and abrasion resistance, the generation of fuzz and thread breakage during weaving of the carbon fibers is suppressed, and the handling properties thereof are greatly improved.

(2) Coupled with the effect of (I) above, the adhesion between the carbon fibers and the matrix resin is also good, so the interlaminar shear strength of the resulting composite is also improved.

(3) A nonionic emulsifier can be used to form a uniform and stable aqueous emulsion, and in this state it can be applied to carbon fibers.

<Example> First, the following bisphenol type polycarbonate epoxy compounds represented by the general formula (I) or (I) were synthesized.

・A-1D In general formula (I), R is (FH3 -CH2CH20COCH2CH2-1Y is -C-1n
is 3°O crystal 3 - In the general formula (I) of -A-2, R, Y and nH3 H3, In the general formula (It) of A-3, R, Y and n are A
Same as -1, X is 10-P- chant A-42 In general formula (I), R force;= 3/1
(molar ratio), random bond, H3 Y is 10-1n is 4゜■ H3 ・A-5D In general formula (I), R force is the same as A-1, Y is -5-1n is 6゜■ ・A-6: In general formula (I), R is the same as A-1, Y is -CH2-1n is 4, and X is the same as A-3.

・A-7: In general formula (I), R is the same as A-4, and Y, n, and X are the same as A-6. ・A-8 In general formula (I[), R, Y, and X is A
-7, where n is 11°A-1 to A-3, and the synthesis method is listed below. A-
The synthesis of 4 to A-8 was carried out according to the synthesis of A-1 to A-3.

- Synthesis method of A-1: After stirring, a 14-volume four-loop flask equipped with a reflux condenser, a dropping funnel, and a thermometer was used. Into this flask, polycarbonate 500 with a molecular weight of 1000 obtained by addition polymerization of ethylene carbonate using bisphenol A as a starting material/(0.5 mol) Torifluoroboron etherate 3.0 f/(0.5% by weight)
and further diluted with epichlorohydrin 9 at 60-80°C.
2.517 (I, 0 mol) was added dropwise. After finishing dropping, 6
Stir at 0-80 °C for 2 hours, add 56.1 f (I, 0 mol) of potassium hydroxide at 80-100 °C, continue stirring at that temperature for 3 hours, and remove by-product salts. , product (A-1) was obtained.

・Synthesis method of A-2: In the same flask as in the case of A-1, add dimethyldichlorosilane 129 f (I°0 mol)
and pyridine 79.19 (I, 0 mol) and addition polymerized with ethylene carbonate using bisphenol A as a starting material. Polycarbonate 5 with a molecular weight of 1000.
00g (0.5 mol) was added dropwise at below 40°C and stirred for 2 hours after the completion of the dropwise addition. Next, pyridine 79.1y (I,
0 mol) and glycidol 74y (I, 0 mol) at 40
The mixture was added dropwise at a temperature below 0.degree. C., and after the addition was completed, the mixture was stirred at room temperature for 2 hours. Then, the by-produced salt was removed to obtain product (A-2).

・Synthesis method of A-3: Add 153.3 g (I, 0 mol) of phosphorus oxychloride and 79.1 f (I, 0 mol) of pyridine to the same flask as in the case of A-1, and add bisphenol. Polycarbonate 500i with a molecular weight of 1000 obtained by addition polymerizing ethylene carbonate using A as a starting material
0.5 mol) was added dropwise at 40° C. or lower, and the mixture was stirred for 2 hours after the addition was completed. Then 158.2 g (2.0 mol) of pyridine
and glycidol 148y (2.0 mol) were added dropwise at 40°C or below, and the product (A-
3) was obtained.

Next, using A-1 to A-8 etc. synthesized in this way, the first
Sizing agent listed in the table (Examples 1 to 8, Comparative Examples 1 to 3)
adjusted.

In each case, the carbon fibers were treated, a composite was molded, and the results were tested and evaluated as shown in Table 2.0 Carbon fiber sizing/aging treatment: Commercially available PAN-based carbon fibers (8μ/3000 filament) was desized with an organic solvent, and each sizing agent was applied to it with an active ingredient adhesion amount of 0.7.
It was impregnated by a dipping method so as to have the same weight percent, and after drying, it was heat-treated in an oven at 150° C. for 30 minutes.

・Composite molding: Add 100% of Epicoat 828 (manufactured by Shell, bisphenol A diglycidyl ether monomer) to the carbon fibers sized as described above.
f+ boron trifluoride.

5y of monomethylamine + 259 of methyl ethyl ketone
This prepreg was impregnated with a resin liquid consisting of and semi-cured at 120°C to create a one-sided prepreg.The prepreg was laminated in a mold and pressurized at 170°C for 1 hour. %) = 60% composite was molded.

- Fluff and thread breakage test: The carbon fibers sized as described above were tested using a TM type conjugation catheter (manufactured by Mahayana Kagaku Seiki Co., Ltd.) with a load of 509/3000 filament,
θ=150 degrees, rubbing length 30 mm, chrome plated metal machine 1
A friction test between fiber and metal was performed by reciprocating 500 times at a speed of 50 times/min.Separately, using a rubbing tester (manufactured by Toyo Seiki Co., Ltd.), the inner angle was 35 degrees, the twist was made once, and the friction length was A fiber-to-fiber friction test was performed by reciprocating 500 times at a speed of 20M1100 times/min. Both were evaluated using the following 5-level criteria.

A = Almost no fluff is generated.

B=Only singular fuzz is generated.

C=Fuzz occurs in clusters.

D = fuzz occurs frequently and some parts break 0 E = 3000 filament breaks 0 Interlaminar shear strength test: For the composite molded as above, A
Measured according to STM D-2344 (ILSS).

・Emulsification stability test: Prepare a 10 weight multi-emulsion of the active ingredient of an aqueous emulsion-type sizinc agent, and test at 20°C x 7
I left it for days. Then, it was evaluated according to the following 3-level criteria: O = No separation △ = Cream separation product floated × = Sedimentation occurred (Table 1) Values in the table are parts by weight. *1 is Epicoat 828 (manufactured by Shell, bisphenol A diglycidyl ether monomer, *2 tl-1 Bicor) 1001 (manufactured by Shell,
Bisphenol A diglycidyl ether oligomark,
The above are Epoquin compounds used in conventional sizing agents. *
3 is water, *4 is methyl ethyl ketone, the above is a solvent, and the active ingredient of each sizing agent is the solvent.

*5 is polyoxyethylene (25 moles) tristyrenated phenyl ether, *6 is polyoxyethylene 7 (30 moles tetrabenzylated phenol ether, the above is an emulsifier. *7 is oleyl oleate, a smoothing agent.

Table 2 Note) - indicates that the water-based emulsion was not used.

From the results in Table 2, the effects of the present invention as described above are clear.

Claims (1)

[Scope of Claims] 1. A sizing agent for carbon fibers, characterized by containing a bisphenol type polycarbonate epoxy compound represented by the following general formula (I) or (II). General formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ General formula (II): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [However, R is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ and /
Or ▲There are mathematical formulas, chemical formulas, tables, etc.▼ singly or in combination, and in the case of a mixture, either block combination or random combination is acceptable. Y is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or -CH2-. n is 1
An integer between ~30. X is a residue selected from the following i) or ii) {In these residues, -O- is bonded to the terminal glycidyl group of general formula (II)}. i) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(Z_1, Z_
2 is CH_3- or ▲There are mathematical formulas, chemical formulas, tables, etc.▼
) ii) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (Z_3 is R'O- or ▲
There are mathematical formulas, chemical formulas, tables, etc.▼, where R' is an alkyl group, alkenyl group, or substituted phenyl group having 1 to 18 carbon atoms)] 2 In general formula (I) or (II), n is 1 to 10
The sizing agent for carbon fibers according to claim 1, which is an integer of . 3 In general formula (I) or (II), R is ▲numerical formula,
The sizing agent for carbon fibers according to claim 2, which has chemical formulas, tables, etc.