JPS6233872A - 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, by adding a sizing agent to carbon fibers, this sizing agent bundles the carbon fibers, gives flexibility to the carbon fibers, improves the abrasion resistance of the carbon fibers, and improves the abrasion resistance of the carbon fibers. Efforts have been made to improve the essentially insufficient adhesion between the composite material and the matrix resin to increase the interlaminar shear strength of the resulting composite.

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.

Previously, there is a sizing agent that uses bisphenol A diglycidyl 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, since it uses organic solvents such as methylene chloride and dichloroethane, there is a risk of toxicity and flammability, and there are problems in that it is less effective in suppressing the occurrence of fuzz and thread breakage during weaving of carbon fiber. .

Bisphenol A epoxy resin (Ehicoat 8)
28 and Epicor) 1001 mixed in a specific ratio,
There is a sizing agent that is used as an aqueous emulsion using a polyoxyethylene nonionic surfactant as an emulsifier (both manufactured by Shell Co., Ltd.) (Japanese Patent Laid-Open No. 57-171767
). 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 thread breakage during weaving of carbon fiber 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. 5
9-9664). This improves the adhesion between the carbon fiber and the IJ sock resin.

This type of sizing agent improves the adhesion between carbon fibers and matrix resin, and improves the interlaminar shear strength of the resulting composite, compared to the conventional sizing agent that uses bisphenol A diglycidyl ether. However, since it contains a tertiary amine group, the epoxy group changes over time, and as a result, the carbon fiber treated with the sizing agent loses its flexibility over time and becomes hard. There is a problem in that fuzz and yarn breakage increase during weaving of carbon fibers.

In summary, conventionally proposed sizing agents for carbon fibers are those that are free of toxicity or flammability, or that improve the adhesion between carbon fibers and matrix resin to improve the interlaminar shear strength of the resulting composite. However, there is no one that fully exhibits both of these effects and at the same time sufficiently exhibits the effect of suppressing the occurrence of fuzz and thread breakage during weaving of carbon fibers.

<Problems to be solved by the invention> The present invention solves the conventional problems as described above.
It eliminates the necessity of using organic solvents and eliminates the danger of toxicity and flammability, and also provides carbon fibers with sufficient binding power and abrasion resistance, suppressing the occurrence of fluff and thread breakage, and improving the carbon fibers. The object of the present invention is to provide a sizing agent for carbon fibers that greatly improves handleability and further improves the adhesion between carbon fibers and matrix resin, thereby imparting excellent interlaminar shear strength to the resulting composite.

<Means for Solving the Problems> As a result of intensive research from the above viewpoint, the present inventors discovered that a specific polyalkylene ether epoxy compound is correctly and suitably suited, and have now completed the present invention. It was.

That is, the present invention relates to a sizing agent for carbon fibers characterized by containing a polyalkylene ether epoxy compound represented by the following general formula (1).

[However, Z is a residue of mono- to trihydric alcohol or phenol. R is selected from alkylene groups having 2 to 4 carbon atoms, singly or as a mixture; in the case of a mixture, the part surrounded by 7 is a mixture with block or run OH; in the case of a mixture, m
The enclosed part is a block or random combination.

The part enclosed by n is! The part bounded by m and the part bounded by m are blocks or integers from 0 to 40, m is an integer from 1 to 5, and n is 1 determined by the valence of 2.
An integer between ~3. ] Regarding Z in the above general formula (1), monohydric alcohols include ethanol, propatool, butanol, octatool, dodecanol, etc., and dihydric alcohols, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, Triethylene glycol, polyethylene glycol, polytetramethylene glycol, polyglopylene glycol, etc., and trivalent alcohols include glycerin, trimethylolethane, trimethylolpropane, etc. Similarly, regarding Z, monovalent 7 enols include phenol, phenylphenol, octylphenol, nonylphenol, styrenated phenol, benzylated phenol,
Cumylphenol, cresol, etc., and divalent phenols such as bisphenol A1 and bisphenol F1.
Bisphenol S1 Hydroquinone, Resorci/-p
, '4, and further trivalent 7 enols include pyrogallol and the like. Among these, bisphenols, and therefore Z is preferably a bisphenol residue. 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. Further, in the general formula (1), l is an integer of 5 to 10, and R is an ethylene group/globylene group + butylene group≧4/l
(molar ratio) is more preferable. In this case, the polyalkylene/ether epoxy compound represented by the general formula (1) exhibits solubility or self-emulsifying property in water, and the interlaminar shear strength of the resulting composite is further improved. This is because the expression of the effect becomes even more remarkable.

In addition to the polyalkylene/ether epoxy compound represented by the general formula (1), 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. Examples of sizing agents include bisphenol A diglycidyl ether, novolak glycidyl ether, or N, N, N, N.
- Epoxy compounds such as tetraglycidyl diaminodiphenylmethane may be used, fatty acid esters such as stearyl laurate, lauryl stearate or oleyl oleate may be used as smoothing agents, and surfactants may be used.
Nonionic surfactants include polyoxyethylene (6 moles) nonylphenyl ether or polyoxyethylene (30 moles) 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 polyalkylene/ether epoxy compound represented by the general formula (1).

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, and after impregnating the carbon fiber with the sizing agent, it is dried with hot air, an infrared lamp, or the like. Upon application, the sizing agent is used as it is or in the form of an aqueous solution or emulsion with a small amount of an 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 fibers is usually 0.2 to 6% by weight, preferably 0.3 to 2% by weight, calculated as the active ingredient.

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

(1) It can be made into a uniform and stable aqueous solution or emulsion as it is or with a small amount of emulsifier, and can be applied to carbon fibers in this state, so there is no danger of toxicity or flammability.

(2) 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.

(3) Coupled with the effects of (1) and (2) above, the adhesion between the carbon fibers and the matrix resin is also good, which improves the interlayer shear strength of the resulting composite. Regarding the polyalkylene ether epoxy compounds shown in 1), the following A-1 to A-9 were synthesized.

A -1; (X')(AYl)(E)s(Z
') (E) 5 (AYl) (X') is a bisphenol A residue. These are the same below.

Block] A 2: (X”) (AY2) 3 (P) 4 (E)
3(Z')(E)3(P)4(AY2)3(X'') [However, Y2 is -OH, P is oxypropylene group. These are the same below. Random] A -3; (Z2)( E)4(AY')3(X")
[However, Z2 is ○CH2-oo-. Random] A-
4: (Z3) ((E), (Ay2) (Xl)) 3A
5: (X”) (AY”) 5 (P) 5 (E)
10(Z')(E)10(P)5(AYl)5(X")
[However, z4 is -OCHz CHz Oo random]
A -6; (X')(AY")2(P)6(E)2
(Z5) (E) 2 (P) 6 (AY”) 2 (Xl) [However, z5 is a bisphenol S residue. Random] A 7
: (Z') (E) 4 (AY") 2 (X") [However,
Z6 is CrzHzsO-. Random] A 8:
(X”) (AY”) 2 (P) (E) 6 (Z”) (E
)6(P)(AY”)2(X') [However, block] A-9: (X”)(AY”)3(E)7(Z5)(
E), (AYl)3(X”) [However, block] The synthesis method for A-1 and A-2 is listed below.A-
The synthesis of Examples 3 to A-9 was carried out according to the synthesis of A-1 and A-2.

Synthesis method of A-1: An 11-volume four-loop flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer was used.

To this flask, 10 moles of ethylene oxide was added and polymerized using bisphenol A as a starting material, and the molecular weight was 668.
334 g (0.5 mol) of polyoxyethylene ether
and 6.7 g (2.0% by weight) of potassium hydroxide,
Glycidol 74g (1
, 0 mol) was added dropwise. After the dropwise addition was completed, the mixture was stirred at the same temperature for 1 hour, and the potassium hydroxide was neutralized with orthophosphoric acid. Furthermore,
Add 2.0 g (0.5% by weight) of boron trifluoride etherate and mix with epichlorohydrin 407!1F at 60-80°C.
(4.4 mol) was added dropwise. Continue to 90-100℃
Stir for 2 hours at
A 40% aqueous solution containing 7IC (4.4 mol) was gradually added and stirring was continued at that temperature for 3 hours. After dehydration under reduced pressure, by-produced salts were removed to obtain product (A-1).

Synthesis method of A-2: A 1.51 autoclave was used. In this autoclave, bisphenol A228
1 iF (1,0 mol), xylene 250 m as solvent
1 and 7.0 g of potassium hydroxide as a catalyst,
Under conditions of 3 to 5 m/d at 110 to 120°C, 352 g (8 mol) of ethylene oxide and 3 mol of propylene oxide
A mixture of 489 (6 moles) and 444 g (6 moles) of glycidol was injected over a period of 6 hours and allowed to react. After press-fitting, 1
The mixture was stirred at 25° C. for 2 hours under conditions of 5ky7att. The reaction product was taken out, and the catalyst was separated from each other using an adsorbent, and then the solvent was removed to obtain 1360 g of polyalkylene glycol ether. Add 6.8 g (0.5% by weight) of this product, trifluoroboron etherate,
2.2 mol of shrimp chlorohydrin/204fc) was added dropwise at ℃. After completing the dropwise addition, stir at 90 to 100°C for 2 hours.
124 g (2.2 mol) of potassium hydroxide at 0-100°C
A 40% aqueous solution containing was added, and stirring was continued at the same temperature for 3 hours. After dehydration under reduced pressure, the by-product salts were removed and the product (A
-2) was obtained.

Next, using A-1 to A-9 etc. synthesized in this way, the first
Sizing agent listed in the table (Examples 1 to 9, Comparative Examples 1 to 3)
adjusted.

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

The results are shown in Table 2.

- Carbon fiber sizing process 2 Commercially available PAN-based carbon fiber (7μ/3000 filament) was desized with an organic solvent, and each sizing agent was added to it with an active ingredient M amount of 1.0.
It was impregnated by a dipping method so as to correspond to the weight ratio, and dried in an open air at 120° C. for 5 minutes.

・Composite molding: Add 100 g of Ebicor) 828 (manufactured by Shell, bisphenol A diglycidyl ether monomer) to the carbon fiber sized as described above.
+ impregnated with a resin liquid consisting of 5 g of boron trifluoride monomethylamine + 25 g of methyl ethyl ketone,
It was semi-cured at 120° C. to create a one-sided bripreg.

This prepreg was laminated in a mold and pressurized at 170°C for 1 hour.
A 60% composite was molded.

・Fuzz and thread breakage test: Carbon fibers sized as described above were tested using a TM type conjugation catheter (manufactured by Daiei Kagaku Seiki Co., Ltd.) with a load of 50 g/3000 filament, 02150 degrees, abrasion length of 30 mm, and chrome-plated metal. The comb was moved back and forth 500 times at a speed of 150 times/min to remove the fibers.
A metal-to-metal scratch test was conducted. Separately, using a rubbing tester (manufactured by Toyo Seiki Co., Ltd.), twist once at an internal angle of 35 degrees.
A fiber-to-fiber abrasion test was carried out by reciprocating 500 times at a speed of 100 times/min with a rubbing length of 20 m.

Both were evaluated using the following 5-level criteria.

A = Almost no fuzz is generated.

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.

・Comprehensive judgment of fuzz and thread breakage: Fuzz,
Thread breakage was comprehensively judged.

Good 2 The results of the above TM method and rubbing method are both A.
Or if B is defective = if there is CXD or E in the results of the above TM method and rubbing method - Interlaminar shear strength test: The composite molded as above was measured according to ASTM D-2344 (
ILSS).

- Emulsion stability test: A multi-10 weight emulsion of the active ingredient of each sizing agent was prepared and left at 20°C for 7 days. Then, evaluation was made using the following three-level criteria.

○ = No separation Δ = Creamy separated product floated × = Sedimentation occurred Table 1 Note) Values in the table are parts by weight. *1 is Epicoat 828 (manufactured by Shell, bisphenol A diglycidyl ether monomer), *2u Epicoat 1001 (manufactured by Shell, bisphenol A diglycidyl ether oligomer), and the above are epoxy compounds used in conventional sizing agents. *3 is Polyoxyethylene (10 mol) lauryl ether, *4
is polyoxyethylene (15 moles) nonylphenyl glycidyl ether, *5 is polyoxyethylene (25 moles) tristyrenated phenyl ether, "*6 C, l-
"Lioxyethylene (30 mol) tetrabenzylated phenylphenol ether, the above is an emulsifier. *7 is water, *
8 is methyl ethyl ketone, the above is a solvent, and the active ingredient of each sizing agent is the solvent.

Note in Table 2) - indicates that it was not made into an aqueous solution or emulsion.

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 polyalkylene ether epoxy compound represented by the following general formula (I). General formula (I): ▲Mathematical formulas, chemical formulas, tables, etc.▼ [However, Z is a residue of mono- to trivalent alcohols or phenols. R is selected from alkylene groups having 2 to 4 carbon atoms, singly or as a mixture; in the case of a mixture, the part between the l's is a block or random bond; Y is OCH_2CH-
CH_2 alone or ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is a mixture of CH_2 and OH, and in the case of a mixture, the part enclosed by m is a block or random combination. In the part bounded by n, the parts bounded by l and the part bounded by m are blocks or random combinations. X is H or ▲There are mathematical formulas, chemical formulas, tables, etc.▼. l is an integer from 0 to 40, m is an integer from 1 to 5, and n is 1 determined by the valence of Z.
An integer between ~3. 2. The sizing agent for carbon fibers according to claim 1, wherein Z in general formula (1) is a bisphenol residue. 3. The sizing agent for carbon fibers according to claim 2, wherein l in the general formula (I) is an integer of 5 to 10, and R is ethylene group/propylene group + butylene group ≧4/1 (molar ratio) .