JPS61252365A - 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.

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 are inherently brittle fibers with low elongation, fluffs and thread breakage easily occur due to mechanical friction.And these fuzz and thread breakages significantly affect the handling of carbon fibers. and the physical properties of the composite. Therefore, a sizing agent is applied to the carbon fibers, the sizing agent is used to bundle the carbon fibers, and gives the carbon fibers 7 lexibilities and properties.
In addition to improving the abrasion resistance of the carbon fibers, efforts have been made to improve the essentially insufficient adhesion between the carbon fibers and the matrix resin to improve the interlaminar shear strength of the resulting composite. There is. The present invention relates to such a sizing agent.0 <Prior art and its problems> Conventionally, as a sizing agent for carbon fibers, the following sizing agents using aromatic glycidyl ethers and aromatic glycidyl amines have been proposed. First, there is a sizing agent that uses bisphenol A diglycidyl ether (Japanese Patent Publication No. 57-15229). This is a sizing agent that uses a compound similar to that of the matrix resin in order to improve the adhesion between the carbon fiber and the matrix resin. It is what you use. Sizing agents of this type certainly improve the adhesion.

However, when weaving carbon fibers, when the carbon fibers are required to have cohesive strength and especially 7 flexibility, such performance is extremely insufficient, and the effect of suppressing the occurrence of fuzz and yarn breakage during weaving is low. Additionally, since this type of sizing agent requires the use of organic solvents such as methylene chloride and dichloroethane, there is a problem in that there is a great danger of toxicity and flammability.

In addition, a mixture of bisphenol A type epoxy ffR fat (-1-Piquat 828 and Ebicor 1001, both manufactured by Shell) was made into an aqueous emulsion using a polyoxyethylene nonionic surfactant as an emulsifier. There is a sizing agent to be used (JP-A-57-17
1767) o In this case, since no organic solvent is used, there is no danger of toxicity or flammability. However, 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 yarn breakage during weaving of carbon fibers and the interlayer shear strength of the resulting composite.

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

This type of sizing agent has a higher content of epoxy groups than the conventional sizing agent using bisphenol A diglycidyl ether, so the adhesion between carbon fibers and matrix resin is better, and the resulting composite is better. The interlaminar shear strength of is improved. However, the problem is that the epoxy group tends to change over time, and carbon fibers treated with this sizing agent lose their flexibility and become hard over time, and that fuzz and thread breakage increase during weaving of the carbon fibers. On the other hand, there is an example in which glycidyl ether or glycidyl ester consisting of abiethyl group is used as a coupling agent between carbon fiber and matrix resin (Japanese Patent Application Laid-Open No. 51-11111).
-144468) o This improves the adhesion between the carbon fiber and the unsaturated matrix resin. When this coupling agent is used, compared to the conventional sizing agent that uses bisphenol A diglycidyl ether, the adhesion between the carbon fiber and the unsaturated matrix resin is better, and the interlaminar shear strength of the resulting composite is lower. get well. However, since this coupling agent contains only one oxirane ring in its molecule, when it is used in a composite using epoxy resin as a matrix resin, it acts as an intermediate layer formed at the interface between carbon fiber and matrix resin. has a low concentration of oxirane rings, so when carbon fiber coated with this coupling agent is impregnated with matrix resin, the curing agent diffuses from the matrix resin into the layer of coupling agent, reacts with the oxirane rings, and becomes strong. However, there is a problem in that the interlaminar shear strength of the resulting composite still does not reach a sufficient level.

In summary, conventionally proposed sizing agents for carbon fibers impart 7 flexibility to carbon fibers, improve the abrasion resistance of carbon fibers, and suppress the occurrence of fuzz and thread breakage during weaving of carbon fibers. There is no material that can sufficiently exhibit the effect of increasing the interlaminar shear strength of the composite obtained by improving the adhesion between carbon fiber and IJ sock resin. The reality is that solvents can be toxic and even flammable.

<Problems to be solved by the invention> The present invention solves the conventional problems as described above.
It provides carbon fibers with sufficient cohesive strength and abrasion resistance, greatly improves the handling properties of the carbon fibers by suppressing the occurrence of fuzz and thread breakage, and further improves the adhesion between the carbon fibers and the matrix resin. The purpose of the present invention is to provide a sizing agent for carbon fibers that can impart excellent interlaminar shear strength to a composite made of carbon fibers, eliminate the necessity of using organic solvents, and eliminate the danger of toxicity and flammability.

As a result, it was discovered that a specific abiethylamine derivative epoxy compound having a high oxirane ring concentration was correctly and suitably suited, and the present invention was completed. One or more sizing agents for carbon fibers characterized by containing a derivative epoxy compound, which may be the same or different at the same time, and if they are different, random bonding or block bonding. But that's fine. Here, n
is 0 or an integer from 1 to 6, and R is water. ] The sizing agent according to the present invention preferably contains the abiethylamine derivative epoxy compound represented by the general formula (I) in an aqueous system in that it does not require the use of an organic solvent. Containing a compound in an aqueous system means that the sizing agent is used in a system with water as the continuous phase. The affinity for water of the abiethylamine derivative represented by the general formula (1) is determined with respect to X and Y in the general formula (1), and R
, R: varies depending on the content of n, as the abiethylamine derivative epoxy compound exhibits self-emulsifying properties or exhibits emulsifying properties in the coexistence of an appropriate emulsifier, for example, R, R. An appropriate emulsifier is required when ' is a methyl group and n is smaller than 3. Of course, even when the abiethylamine derivative epoxy compound exhibits self-emulsifying properties, there is no problem in using an appropriate emulsifier. In any case, the emulsifiers used in the present invention include polyoxyethylene abiethyl ether, polyoxyethylene hydroabiethyl ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene benzylated phenyl ether, and holoxyethylene. Surfactants such as nonylphenyl ether are preferred. Regarding X and Y in the general formula (1), when R and R1' are both hydrogen and n is larger than 6, the affinity of the abiethylamine derivative epoxy compound to water is even better, but the affinity with the matrix resin is This is undesirable because it lowers adhesion and lowers the interlayer shear strength of the resulting composite. In general, the interlaminar shear strength of the resulting composite is good when n is close to 3 with respect to X and Y in general formula (1).

In addition to the abiethylamine derivative epoxy compound represented by the general formula (I), the sizing agent according to the present invention may optionally contain conventional sizing agents, smoothing agents, surfactants, etc. to achieve the effects of the present invention. It can be contained within a range that does not cause any damage. To illustrate these, as a sizing agent,
Epoxy compounds such as bisphenol A diglycidyl ether type, novolac type glycidyl ether type, or N,N,iN-tetracricidyldiaminodiphenylmethane are used, and as a smoothing agent, stearyl laurate, lauryl stearate, oleyl oleate, etc. In addition, there are nonionic surfactants such as polyoxyethylene (6 mol) nonyl 7-enyl ether or haphoryoxyethylene (30 mol) tristyrenated phenyl ether. . In either case, the sizing agent according to the present invention usually contains 10% by weight or more, preferably 50% by weight or more of the abiethylamine derivative epoxy compound represented by general formula (1).

The abiethylamine derivative epoxy compound represented by the general formula (1) is produced in the first step of reacting abiethylamine as a raw material with glycidol, ethylene oxide and/or propylene oxide without a catalyst, and then reacting the reaction product with trifluorofluoride. The second step is to react epihalohydrin to obtain a halohydrin ether in the presence of an acidic catalyst such as a hydrogen chloride or a hydrogen ether complex, and further, the halohydrin ether is subjected to an intramolecular ring-closing reaction with an aqueous caustic solution to form diglycidyl. The third step of converting it into an ether can be synthesized by the above steps. At this time, by increasing the molar ratio of epihalohydrin to glycidol used in the second step, it is possible to introduce more oxirane rings into the hydroxyl groups of the reaction product from the first step. ), epichlorohydrin is also industrially more advantageous.

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. When applied, the sizing agent is made into an aqueous solution or emulsion, or an organic solvent solution, and is usually adjusted to 10% by weight or less, preferably 0.5 to 3% by weight, in terms of the active ingredient. The amount of the sizing agent attached to the carbon fiber is usually 0.2 to 5% by weight, preferably 0.3 to 2% by weight in terms of the active ingredient. Therefore, the present invention has the following effects in summary.

(1) Since carbon fibers can be endowed with excellent binding strength and abrasion resistance, the occurrence 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 (1) 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) It does not require the use of organic solvents, can be used in a uniform and stable aqueous system, and has no danger of toxicity or flammability.

EXAMPLES Hereinafter, the structure and effects of the present invention will be made clearer with reference to Examples, but the present invention is not limited to these Examples.

<Example> First, A-1 to A-7 were synthesized using the abiethylamine derivative epoxy compounds represented by the general formula (1) at molar ratios with the synthesis raw materials listed in Table 1.

The synthesis methods of Table 1 A-1 and A-2 are listed below from 0A-3 to
A-7 was synthesized in the same manner as A-1 and A-2.

- Synthesis method of A-1: A 1J volume four-loop flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer was used. Under a nitrogen stream, 142.5 g (0.5 mol) of hair vinyl amine (Amine D manufactured by Hercules) was added, and while maintaining the temperature at 110-130°C, glycidol 29.
6f (4 mol) was added dropwise over 2 hours. After the dripping is finished,
The reaction continued for 60 minutes to completion. Then, 2.2 g (0,s wt%) of boron trifluoride etherate was added as a catalyst, and 1 llli of epichlorohydrin was added at 60-80°C.
' (1.2 mol) was added dropwise. After this, 90-100℃
Stir for 2 hours at 80-100°C, add potassium hydroxide 6
Add 40ti aqueous solution containing 4f (1.2 mol)
After 0 decompression treatment with continued stirring for an hour, the by-product salts were removed,
Synthesis method of 0/A-2 that yielded product A-1: Add abiethylamine (previously mentioned) 28 to an autoclave of t, Sj.
Prepare 5g (1 mol), 3~5~/i, 120~14
A mixture of glycidol 148f (2 mol) and ethylene oxide 352 g (8 mol) was reacted at 0°C for 3 hours, and then aged at the same temperature for 1 hour.The reaction product was added with boron trifluoride. Add 8.9 g (0.5% by weight) of epichlorohydrin at 60-80°C.
9 mol) was added dropwise over 2 hours. After completion of dripping, 90~
Stirring was continued at 100°C for 2 hours, and at 80-100°, a 40% aqueous solution containing 225 g (4 moles) of potassium hydroxide was added and stirring continued for 3 hours. After the vacuum treatment, the by-produced salt was removed to obtain product A-2.

Next, using A-1 to A-7 etc. synthesized in this way, a second
Sizing agent listed in the table (Examples 1 to 7, Comparative Examples 1 to 4)
adjusted.

In each case, carbon fibers were treated and composites were molded and tested and evaluated as follows.

The results are shown in Table 3.

- Sizing treatment of carbon fiber: Commercially available PAN-based carbon fiber (7μ/3000 filament) was desized with an organic solvent, and each sizing agent was applied to it to a coating amount of 1.0% of the active ingredient.
It was impregnated by a dipping method so as to have the same weight percent, and was dried in an oven at 120° C. for 5 minutes.

・Composite molding: Add 1 ounce of Eviny) 828 (manufactured by Shell, bisphenol A diglycidyl ether monomer) to the carbon fiber sized as described above.
f+ poron trifluoride monomethylamine 5f+
A unidirectional prepreg was prepared by impregnating a resin liquid consisting of 25f of methyl ethyl ketone and semi-curing at 120°C. This prepreg was laminated in a mold and pressurized at 170°C for 1 hour, and vf (volume % of carbon fiber in the composite)
=60% composite was molded.

- Fluff and thread breakage test: Carbon fibers sized as described above were tested using a TM type conjugation catheter (manufactured by Daito Kagaku Seiki Co., Ltd.), load 501i'/3000 filament, θ = 150 degrees, rubbing length 30 degrees, A chromium-plated metal comb was reciprocated 500 times at a rate of 150 times/min to perform a fiber-to-metal abrasion test. Separately, using a rubbing tester (manufactured by Toyo Seiki Co., Ltd.),
A fiber-to-fiber abrasion test was carried out by reciprocating 500 times at a rubbing length of 20 m and a speed of Zoo times/min. Both were evaluated according to the following 5-level criteria: OA = almost no fluff.

B=Only singular fuzz is generated.

C=Fuzz occurs in clusters.

D=Fuzzing occurs frequently and some parts are cut off.

E=3000 filament breaks.

φ interlaminar shear strength test: The composite molded as described above was measured according to ASTM D-2344 (
ILSS).

- Emulsion stability test: A 10% by weight emulsion of the active ingredient of the aqueous emulsion type sizing agent was prepared and heated at 20°C x 7
I left it for days. Then, evaluation was made using the following three-level criteria.

〇=No separation Δ = cream isolate floated ×=Precipitation occurred Table 2 Note) Values in the table are parts by weight.

*1 is Epicor 828 (listed above), *2 is Epicor 1001 (listed above), *3 is abiethyl glycidyl ether, and the above are epoxy compounds used in conventional sizing agents.

*4 is polyoxyethylene (10 mol) lauryl ether, *5 is polyoxyethylene (15 mol) nonylphenyl glycidyl ether, *6 is polyoxyethylene (
25 mol) tristyrenated methyl phenyl ether, *
7 is polyoxyethylene (10 mol) hydroabiethyl ether, and the above is an emulsifier.

*8 is water, *9 is methyl ethyl ketone, above is solvent,
The active ingredients of each sizing agent are those excluding these solvents.

Table 3 Note) - indicates that the water-based emulsion was not used.

From the results in Table 3, 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 an abiethylamine derivative epoxy compound represented by the following general formula (I). General formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [However, for X and Y, ▲There are mathematical formulas, chemical formulas, tables, etc.▼
, ▲Mathematical formulas, chemical formulas, tables, etc.▼ One or more types selected from ▼ may be the same or different at the same time, and if they are different, they may be combined randomly or in blocks. Here, n is 0 or 1
An integer of ~6, R is hydrogen or a methyl group, R' is hydrogen or ▲There are numerical formulas, chemical formulas, tables, etc.▼. 2. The sizing agent for carbon fibers according to claim 1, which contains the abiethylamine derivative epoxy compound represented by the general formula (I) in an aqueous system.