JPS599664B2 - Tansoseniiyouhiyoumenshiagezai - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface finishing agent for carbon fibers, and its purpose is to facilitate the handling of carbon fibers in the production of carbon fiber reinforced composite materials, and to improve the quality of carbon fiber reinforced composite materials. It is an object of the present invention to provide a surface finishing agent for carbon fibers that can improve various physical properties of carbon fibers, particularly its interlaminar shear strength.

Carbon fiber has the characteristics of being lightweight, high strength, and high modulus, so as its price has declined, it has attracted attention as a reinforcing material, and carbon fiber reinforced composite materials using it have begun to be produced industrially. I'm getting used to it.

The manufacturing process consists of a so-called surface oxidation treatment process in which carbon fibers are first oxidized in a gas or liquid phase to introduce functional groups such as carboxyl groups and phenolic hydroxyl groups onto their surfaces, and then the surface-treated fibers are treated with bisphenol A. A process of surface finishing with a glycidyl ether type epoxy resin or a sizing agent containing it as a main component to collect the carbon fibers and improve their handling properties, and placing the surface finished fibers in a matrix resin containing a hardening agent. The first step includes an impregnating step.

Note that the subsequent steps are shown in Examples. and,
Conventionally, epoxy resins, unsaturated polyesters, polyimides, etc. have been used as these matrix resins. Since the adhesion between these matrix resins and carbon fibers is naturally very low, the above-mentioned surface oxidation treatment is performed to improve the adhesion. However, this surface oxidation treatment is difficult because carbon fibers are inherently resistant to oxidation, and the oxidation must be carried out within the range of negligible weight loss and negligible strength loss. However, there is a limit to the degree to which functional groups such as carboxyl groups and phenolic hydroxyl groups can be introduced. And the conventional bisphenol A
Surface finishing treatment with a finishing agent whose main component is a glycidyl ether type epoxy resin contributes to the bundling of fiber single filaments and thus improves the handling properties of the fibers, but it also improves the adhesion between the matrix resin and carbon fibers. It is thought that it makes little contribution to Therefore, the interlaminar shear strength (interlaminar strength) of carbon fiber reinforced composite materials obtained through conventional manufacturing processes is
inarShearStrerlgthl below ILSS
) has not yet reached a level that is practically satisfactory, and the current situation is that improving ILSS is one of the most important issues to be solved in the field of composite materials. In view of the above, the present inventors sought a means of improving the adhesion between the matrix resin and carbon fibers, that is, improving ILSS, by selecting a surface finishing agent, and as a result of intensive research, improved the cohesiveness between single fiber filaments. At the same time, the present inventors discovered a surface finishing agent that can improve ILSS by about 10 to 30% compared to conventional products, leading to the present invention.

That is, the present invention relates to the following general formula (wherein X is -CH2-CH-
CH2,, Y is -H or '\CH2-CH-CH2,
R1 and R2 are -H or CH3, n and m are O or 1, respectively. be.

The polyfunctional epoxy compound in the present invention includes N-
N-N/-Nl-tetraglycidylphenylenediamine, N-N-N triglycidylphenylenediamine,
N-N-N/-N'-tetraglycidyldiaminotoluene, N-N-N! monotriglycidyldiaminotoluene,
N-N-N'・N'-tetraglycidyldiaminoxylene, N-N-NL triglycidyldiaminoxylene, (
N/-Nζ-diglycidyltoluidyl)diglycidylamine, (N'-glycidyltoluidyl)diglycidylamine, (N'-N'-diglycidyltoluidyl)glycidylamine, N-N-N/-N' -tetraglycidylxylylenediamine, N-N-N/-triglycidylxylylenediamine, etc. can be used.

In the present invention, containing a polyfunctional epoxy compound means
This also means the case where the compound is contained at 100%, but more preferably the concentration is 20% by weight or less, and even more preferably 0.
．． It is meant in the form of a 5-5% by weight solution or aqueous emulsion. As the solvent used for these solutions, alcohols or mixed solvents of alcohol and ketones, esters, etc. are suitable, and in particular, methyl alcohol, ethyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, or these solvents are suitable. A mixed solvent containing alcohol as a main component is preferred. In addition, the form of the aqueous emulsion is anionic, . Alternatively, it can be obtained by dispersing in water using a nonionic surfactant alone or in combination. Furthermore, the finishing agent of the present invention may also contain a lubricant, a softening agent, a sizing agent, a film-forming aid, etc., which will be described later, as necessary.

Examples of the lubricant include stearic acid, stearic acid alkyl ester, nonionic surfactant, anionic surfactant, silicone resin, and the like.

If silicone resin is used in a large amount, the affinity between the carbon fiber and the resin will decrease, so the amount of silicone resin to be blended must be determined carefully. The content of these lubricants is preferably 30% by weight or less of the total active ingredients contained in the surface finishing agent. Further, examples of the softening agent include nonionic surfactants, polyethylene glycol, polyethylene glycol monoalkyl esters, and the like.

The content of these soil softening agents is desirably 30% by weight or less of the total active ingredients contained in the surface finishing agent. Further, as a sizing agent that can be contained in the carbon fiber surface finishing agent according to the present invention as desired, methyl methacrylate, emer methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, etc. Alkyl methacrylates such as methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, alkyl acrylates such as lauryl acrylate, styrene,
Styrene derivatives such as α-methylstyrene and vinyltoluene, fatty acid pynyl esters such as vinyl acetate and vinyl propionate, unsaturated hydrocarbons such as butadiene and isoprene, halogenated unsaturated hydrocarbons such as vinyl chloride and chloroprene, acrylonitrile, meth unsaturated nitrile compounds such as acrylonitrile; monomethyl esters of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, vinyl acetic acid, alpha-ethyl acrylic acid, angelic acid, itaconic acid, maleic acid or fumaric acid; Unsaturated carboxylic acids such as monoethyl ester, monobutyl ester, maleic anhydride, itaconic anhydride, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, glycidyl methacrylate, glycidyl acrylate, 2-chloro 3-hydroxypropyl One or more ethylenically unsaturated compounds selected from methacrylate, phosphoric acid mono(hydroxypropyl methacrylate) ester, acrylamide, methacrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N-butoxymethylacrylamide, etc. Examples include vinyl-based addition polymers obtained by polymerizing monomers of More preferred is a vinyl addition polymer containing as a constituent component.

In addition, bisphenol A diglycidyl ether type epoxy resin, novolac type epoxy resin, polyether or polyester modified flexible epoxy resin, polyamic acid, etc. can be used in combination as a sizing agent. When carbon fibers are particularly required to have sizing properties, it is extremely effective to add these sizing agent components. The content of these sizing agents is preferably 90% by weight or less of the total active ingredients contained in the surface finishing agent. Furthermore, examples of film forming aids that can be contained in the surface finishing agent for carbon fibers according to the present invention as desired include plasticizers such as dibutyl phthalate and dioctyl phthalate, high boiling point organic solvents, and water. can give.

The content of these film-forming aids is preferably 30% by weight or less of the total active ingredients contained in the surface finishing agent. On the other hand, the polyfunctional epoxy compound contained as an essential component in the surface preparation agent for carbon fibers according to the present invention includes a polyfunctional epoxy compound, a sizing agent, a lubricant, a softening agent, a film forming aid, etc. The content of the active ingredient is preferably at least 10% by weight, and particularly preferably 30% by weight or more.

When the content of the polyfunctional epoxy compound is less than 10% by weight, the advantages based on its polyfunctionality may not be fully utilized. Next, a method of using the surface finishing agent for carbon fibers according to the present invention will be explained. The surface finishing of carbon fibers is usually carried out by immersing the carbon fibers in the surface finishing agent and then drying to remove the solvent or dispersion medium. The active ingredient concentration of the surface finishing agent (solution or emulsion) is preferably 20% by weight or less, and 0.5 to 5% by weight.
A range of % by weight is particularly preferred. Furthermore, when surface finishing carbon fibers is performed using the surface finishing agent of the present invention, the amount of active ingredients deposited on the carbon fibers is within the range of 0.2 to 5% by weight, and these In order to ensure that the components adhere uniformly, the active ingredient concentration in the sizing bath, the impregnation time or speed, the tension of the carbon fiber during impregnation, the squeezing conditions after impregnation with a squeezing roller, the temperature of the sizing bath, and the drying conditions after impregnation. It is preferable to control the following. After being impregnated, the carbon fibers passed through the squeezing roller are dried using an infrared lamp, hot air, or the like at a temperature depending on the type of solvent or dispersion medium for a predetermined period of time to remove volatile components. When surface finishing carbon fibers using the carbon fiber surface finishing agent of the present invention, the first component, for example, the polyfunctional epoxy compound,
attached to the carbon fibers in the manner described above, then the second component,
For example, it can also be carried out by a multi-step process of attaching bisphenol A diglycidyl ether type epoxy resin to carbon fibers.

Carbon fibers to which the surface finishing agent for carbon fibers according to the present invention is applied include carbon fibers, graphite fibers, carbonaceous or graphite fibers or single crystals such as graphite whiskers, and these fibers or single crystals. Examples include mat, woven fabrics, knitted fabrics, etc. as constituent components.

Furthermore, the surface finishing agent for carbon fibers of the present invention can be applied regardless of the starting material (precursor) of carbonaceous or graphite fibers or single crystals. Carbonaceous or graphite fibers or single crystals whose surfaces have been surface activated by surface oxidation treatment or other methods are applicable to the surface finishing agent of the present invention.
Particularly preferred. Compared to conventionally known surface finishing agents, the carbon fiber surface finishing agent containing the polyfunctional epoxy compound of the present invention has a carbon fiber reinforcement that can be obtained by applying the above-mentioned known method when finishing the carbon fiber surface. The interlaminar shear strength of composite materials is improved by about 10 to 30%, and bending strength, impact strength,
It has an excellent effect of improving various properties such as fatigue strength, and also has the effect of improving fiber cohesiveness.

Furthermore, a surface finishing agent containing both the polyfunctional epoxy compound and the vinyl addition polymer containing the oxirane ring-containing unit as a constituent component exhibits remarkable improvements in various physical properties such as interlaminar shear strength and bending strength. At the same time, it is particularly excellent in that it brings about a remarkable improvement in convergence. The remarkable improvement in interlaminar shear strength achieved by the surface soil agent of the present invention is, of course, due to the improvement in the adhesiveness between the fibers and the matrix resin. The improvement is thought to be due to the following reasons.

That is, the interfacial intermediate layer formed by the surface finishing agent according to the present invention has an extremely high concentration of oxirane rings, and when carbon fibers coated with the surface finishing agent are impregnated with a resin matrix, the interfacial layer forms from the matrix phase. It is thought that as the curing agent diffuses into the interface intermediate layer, it reacts effectively with the functional groups introduced on the carbon fiber surface, resulting in the formation of a strong bond with the carbon fiber. It is believed that the interfacial 3 intermediate layer formed from the surface finishing agent according to the present invention forms a mutual diffusion layer with the resin matrix phase and forms a strong bond by taking advantage of its polyfunctionality. Examples are shown below to further clarify the effects of the present invention.

In the examples, parts and % refer to parts by weight (and % by weight).
represents. Example 1 Carbon fiber (high strength yarn,
Tensile strength 300k9/11t1L, tensile modulus 23t/
Mll) tow (consisting of 6,000 single yarns with a diameter of about 8μ) was oxidized with an aqueous sulfuric acid solution of potassium dichromate, and then treated with N-N-N'·N using a bopin sizer. It was sized with a surface finish prepared by dissolving Diamine 207 in methyl alcohol 980r.

Sizing is carried out by placing the carbon fibers in the surface finishing agent bath for 6 m.
The surface finishing agent was allowed to pass through the fibers continuously at a speed of /min to sufficiently penetrate between the single yarns, and the excess surface finishing agent was squeezed out with a squeezing roller, followed by drying at 70°C for 1 minute. I went. The amount of active ingredients in the surface finishing agent attached to the carbon fibers was 2.1% based on the carbon fibers. Next, 43 parts of epoxy resin "Epicote 8828" manufactured by Schiel Co., Ltd. and epoxy resin "ECN1235" manufactured by Civer-Geigy Co., Ltd. (polyglycidyl ether of orthocresol formaldehyde sobolak) were added to the carbon fibers obtained in this way.
After impregnating with a resin composition consisting of 43 parts, boron trifluoride monoethylamine, 4 parts, and 10 parts of acetone,
Aligned on release paper treated with silicone, then 130
A prepreg was prepared by heat treatment at ℃ for 20 minutes.

Note that this prepreg was produced using a drum winder. The length of the blib leg obtained in this way is 2
80mm, width 1007! T7! After cutting into the size of L, stacking 11 sheets and putting them into a mold of the same size, 130
Insert between the hot plates of a hydraulic press heated to 7k
g/Cd at 130°C for 30 minutes and then at 170°C.
Heated at ℃ for 1 hour.

Then, the obtained molded product was placed in an oven at 170℃ for 2 hours.
Time went by that post-queer. The resulting composite contains 58% carbon fiber by volume and its IL
The SS was measured according to the method of ASTM D-2344 and was found to be 9.25 kg/7ILd.

Moreover, the bending strength was measured according to the method of ASTM D79O and was found to be 165 kg/m! It was L. Example
2 As a surface finishing agent, N-N-N'-N'-tetraglycidyl metaxylylene diamine 107 and methyl methacrylate, butyl acrylate, and glycidyl methacrylate were copolymerized at a copolymerization ratio of 35:25:40 (mol%). Using a surface finishing agent prepared by dissolving the copolymerized polymer 10y in a mixed solvent consisting of methyl alcohol 490y and methyl ethyl ketone 490y, the same procedure as in Example 1 was carried out. 'The same carbon fiber used in Example 1 was sized in the same manner.

The amount of active ingredient in the surface finishing agent attached to the carbon fibers was 2.4% based on the carbon fibers. Next, the binding force of the obtained carbon fibers was measured using a TM type binding force tester.

The ranking of conjugation power was performed according to the following criteria. Rank A: Only singular fuzz is generated.

Rank B: Multiple fluffs occur.

Rank C: Fuzz occurs in clusters.

Rank D: Fluff occurs all over the surface.

The results obtained are shown in Table 1.

Next, a composite was prepared from the carbon fibers obtained here in the same manner as in Example 1, and its physical properties were measured.

The resulting composite contained 60% by volume of carbon fiber, had an ILSS of 9.24 kg/Mdl and a flexural strength of 163 k9/Md. Example 3 As a surface finishing agent, N-N-N/-N tetraglycidyl metaxylylene diamine 14y and epoxy resin "Epicote 81001U6y" manufactured by Ciel were dissolved in a mixed solvent consisting of methyl alcohol 6907 and methyl ethyl ketone 290y. Carbon fibers were sized in the same manner as in Example 1, except that the surface finishing agent prepared by the method was used, and the composite physical properties of the obtained carbon fibers were measured.

The amount of active ingredient in the surface finishing agent adhered to the carbon fiber thus obtained was 2.3% based on the carbon fiber.

Further, the ILSS of the composite composite made from the carbon fiber obtained here was 8.93k9/71td.

On the other hand, its bending strength was 157k9/M7l.

Incidentally, the volume content of carbon fiber in the composite prepared here was 57% by volume. Example 4 All procedures were carried out except that N-N-N triglycidyl metaxylylene diamine 207 was used instead of N-N-ma-N'-tetraglycidyl metaxylylene diamine 207 as the polyfunctional epoxy compound. In the same manner as in Example 1, a surface finishing agent was prepared, carbon fibers were sized, and the composite physical properties of the obtained carbon fibers were measured.

The amount of active ingredient in the surface finishing agent adhered to the carbon fiber thus obtained was 2.0% based on the carbon fiber.
Moreover, the ILSS of the composite made from the carbon fiber obtained here was 9.05k9/Md, and its bending strength was 1601<g/Mll.

Incidentally, the volume content of carbon fiber in the composite prepared here was 60% by volume. Example 5 Same as Example 1 except that (NζN-diglycidyltoluidyl)diglycidylamine 20y was used instead of N-N-NζN7-tetraglycidylmethaxylylenediamine 20y as the polyfunctional epoxy compound. A surface finishing agent was prepared, carbon fibers were sized, and the composite physical properties of the obtained carbon fibers were measured.

The amount of active ingredient in the surface finishing agent adhered to the carbon fiber thus obtained was 21% based on the carbon fiber.

Moreover, the ILSS of the composite made from the carbon fiber obtained here was 9.32 kg/Md, and its bending strength was 165k9/M7l.

Incidentally, the volume content of carbon fiber in the composite prepared here was 58%. Comparative Example 1 N-N-N/-N tetraglycidyl metaxylylene diamine 207 in Example 1 was mixed with methyl alcohol 98
Instead of the surface finish prepared by dissolving at 0 V, a 1:1 mixture of Ciel epoxy resins "Epicote 8828" and "Epicote 81001" 207 was prepared by dissolving it in methyl ethyl ketone 9807. Carbon fibers were sized in the same manner as in Example 1 except that a surface finishing agent was used, and the composite physical properties of the obtained carbon fibers were measured.

The amount of active ingredient in the surface finishing agent adhered to the carbon fiber thus obtained was 2.4% based on the carbon fiber.

In addition, the composite made from the carbon fibers obtained here contains 58% by volume of carbon fibers, and its ILS
S is 7.53kg/Mdl while its bending strength is 140k
g/MlL.

Next, using a TM type binding force tester, the binding force of the carbon fibers obtained here was measured in the same manner as in Example 2.

Claims (1)

[Claims] 1 The following general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, X is ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, Y is -
H or -CH_2- ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R_1 and R_
A surface finishing agent for carbon fibers, characterized in that it contains one or more polyfunctional epoxy compounds represented by -H or -CH_3, n and m each representing 0 or 1.