JP2524321B2 - Surface treatment agent for carbon fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a surface treating agent for carbon fibers (hereinafter, simply referred to as a treating agent).

Carbon fiber has excellent strength, elasticity, heat resistance, etc.,
It is used as a reinforcing fiber for composite materials in many situations in the form of filaments and chopped fibers. However, carbon fiber is low in elongation and inferior in flexural wear resistance, and thus, in the manufacturing or processing steps thereof, yarn breakage, yarn damage, fluffing and the like are likely to occur, and the yarn quality is accordingly deteriorated. If yarn breakage or fluffing occurs, the manufacturing or processing characteristics and working environment deteriorate, and if the yarn quality deteriorates, the strength characteristics of the molded product obtained from the composite material using such carbon fiber as a reinforcing fiber Deteriorate. Therefore, there is a demand for a treatment agent that can eliminate the above-mentioned inconveniences associated with carbon fibers.

The present invention relates to a treating agent that meets such a demand.

<Conventional technology and its problems> Conventionally, in order to prevent yarn breakage, fluff, and the like by making the carbon fiber have a converging property and covering and protecting the surface thereof, epoxy resin, phenol resin, polyimide, polysulfone, etc. Various treatment agents are used according to the matrix resin of the composite material using the carbon fiber. And in recent years, various improvements have been observed in these treating agents. For example, an example in which a polyoxyalkylene alkyl ether type or polyoxyalkylene aliphatic ester type emulsifying dispersant having a long-chain aliphatic group is used in combination, and a lubricant such as stearates and silicone resin is also used in combination (Japanese Patent Publication No. 58-43513) etc.

However, such conventional treating agents cannot sufficiently meet the recent high demands on the production or processing characteristics of carbon fibers and the strength characteristics of molded articles obtained from composite materials using the carbon fibers as reinforcing fibers. There is a problem.

<Problems to be Solved by the Invention and Means for Solving the Problems> The present invention solves the above-mentioned conventional problems and provides a new treating agent which meets the above-mentioned demand.

However, as a result of diligent research from the above viewpoints, the present inventors have found that what contains a specific epoxy resin and a specific 2-oxazoline compound in a predetermined ratio is properly suitable.

That is, in the present invention, the following A component and B component are A component / B component = 95 / 5-40 / 6
The treatment agent is characterized by containing 0 (weight ratio).

A component: Phenolic epoxy resin and / or aromatic nitrogen-containing epoxy resin B component: 2 having a boiling point of 140 ° C. or higher represented by the following general formula
-Oxazoline compounds of general formula: (However, X is absent or a divalent aliphatic or aromatic hydrocarbon group) In the present invention, the component A is a phenolic epoxy resin and / or an aromatic nitrogen-containing epoxy resin. Such epoxy resins include 2,2'-bis [p- (2,3-epoxypropoxy) phenyl] propane and 2,2'-bis (2,3
-Epoxypropoxyphenyl) methane or other diglycidyl ether, m-N, N-diglycidylaminophenylglycidyl ether, p-N, N-diglycidylaminophenylglycidyl ether or other triglycidyl ether,
Furthermore, polyglycidyl ethers such as novolac type epoxy compounds and tetraglycidyl (methylenedianiline)
And polyglycidyl amines such as

In the present invention, the component B is a 2-oxazoline compound having a boiling point of 140 ° C. or higher represented by the above general formula. Examples of the 2-oxazoline compound include 1,3-phenylene-
Bis- (2-oxazoline), 1,4-phenylene-bis- (2-oxazoline), 2,2'-bis- (2-oxazoline), 1,4-butylene-bis- (2-oxazoline), etc. Can be mentioned.

The 2-oxazoline compound used in the present invention is an organic compound having two 2-oxazoline rings in the molecule, but it is necessary that the boiling point be 140 ° C. or higher in view of the processing temperature during use. . When the boiling point is lower than this, problems such as foaming and smoke generation during processing may occur, and the surface of the molded product may be easily soiled and the physical properties thereof deteriorate.

The components A and B described above are applied to the carbon fiber as a solution of an organic solvent, or generally as an aqueous emulsion using a surfactant as an emulsifier or a dispersant.
The present invention does not particularly limit the organic solvent used here, but examples thereof include acetone, methyl ethyl ketone, ethyl acetate, dichloromethane and the like. Further, the present invention is not particularly limited to the surfactant used here, but from the purpose of using the carbon fiber, an anionic surfactant containing an alkali metal or an alkaline earth metal is not suitable, Nonionic surfactants are preferred. Examples of such nonionic surfactants include POE ether type nonionic surfactants such as polyoxyethylene (hereinafter abbreviated as POE) alkyl ether, POE alkyl phenyl ether, POE polybenzylated phenyl ether, POE alkyl ester, polyvalent Examples thereof include POE ester type nonionic surfactants such as alcohol partial fatty acid esters and POE polyhydric alcohol partial fatty acid esters, and polyhydric alcohol partial ester type nonionic surfactants.

In the present invention, for example, a lubricant or the like may be used in combination within the range that does not impair the effects of the present invention. Specifically, use in combination with aliphatic esters such as oleyl oleate, stearyl oleate, lauryl oleate, octyl oleate, 2-ethylethoxyoleate, oleyl stearate, oleyl palmitate, oleyl laurate, oleyl isostearate. It can also be done.

The treating agent according to the present invention is actually used by appropriately containing the components as exemplified above, but the essential components A and B are A component / B component = 95/5 to 40/60. (Weight ratio)
Ratio, preferably 92/8 to 50/50 (weight ratio). If the amount of B component is too much out of the above range,
If the B component is too small, the strength property of the finally obtained molded product cannot be sufficiently obtained.

When the treating agent according to the present invention is attached to carbon fibers, the A component and the B component may be simultaneously attached in the same bath, or may be separately attached, and the amount of attachment is 0.01 to carbon fibers. ~ 3.0 wt%, preferably 0.1-2.5 wt%
Is. The amount of adhesion is adjusted by the squeezing ratio of the squeezing roller after impregnation or the rotation speed of the oiling roller and the concentration of the treatment agent, and it is preferable to dry with a heater after the adhesion.

Examples will be given below to make the constitution and effects of the present invention more specific, but the present invention is not limited to the examples.

<Examples and the like> The tests of Examples 1 to 12 and Comparative Examples 1 to 8 to be described later are performed, and the fluff and yarn breakage of the carbon fiber to which the treating agent is attached are evaluated by the following method, and the carbon fiber is used The interlaminar shear strength (ILSS) of unidirectional carbon fiber reinforced plastic (CFRP) cured and molded was measured.

・ Evaluation of fluff and yarn breakage (indicated by fluff and yarn breakage in each table) Using a rubbing tester (manufactured by Toyo Seiki Co., Ltd.), fiber-
A rubbing test between fibers was performed [load 100 g / 3000 filament, internal angle 35 °, 1 twist, rubbing length 20 mm, 500 reciprocating motions at a speed of 100 times / min], and evaluation was performed according to the following five-stage criteria.

5 = no fluff, no yarn breakage 4 = some fluff 3 = fluff 2 = many fluff, yarn break 1 = cut ・ ILSS measurement (indicated by strength in each table) ILSS of CFRP obtained in each example Was measured by ASTM D2344.

 In the following examples, all percentages are by weight.

Examples 1 to 4 and Comparative Examples 1 to 3 70 g of epoxy resin (diglycidyl ether of bisphenol A, epoxy equivalent of 190, trade name Epicoat 828, manufactured by Yuka Shell Co., Ltd.) was added to polyoxyalkylene (PO / EO molar ratio). (1/3, 3 mol) polyoxyethylene (25 mol) pentabenzylated phenyl phenyl ether (18 g), polyoxyethylene (5 mol) octyl phenyl ether (4 g) and oleyl oleate (8 g) were mixed and dissolved by heating at 80 ° C.
Stirring was continued while gradually adding 20 g of warm water at 50 to 60 ° C., and after phase inversion, an emulsion was prepared by further adding 80 g of the same warm water and immediately cooled to 20 ° C. to obtain emulsion a.

Separately, 1,3-phenylene finely pulverized with a jet mill
Bis- (2-oxazoline) 20 g (average particle size 1.2 μ), polyoxyethylene (10 mol) nonyl phenyl ether 2
g and 78 g of water were put in a glass container, glass beads were put therein, and the bottle was tightly capped, and then shaken with a paint shaker for 30 minutes to obtain a dispersion liquid b.

Emulsion a and dispersion b were separately diluted with water, and the amount of epoxy resin in emulsion a and 2-
After adjusting the amounts of both oxazoline compounds to 2%, both water dilutions were mixed in the proportions shown in Table 1,
A treatment liquid was prepared. The carbon fiber is dipped in this treatment liquid, and the squeezing conditions are adjusted so that 50% of the treatment liquid adheres to the carbon fiber, and this is treated at 90 ° C. for 20 minutes and further at 160 ° C. × 1.
Heat treatment was performed for 0 minutes to obtain carbon fibers to which the treating agent was attached.

And although the following is appropriately applied to each of the examples described below, an epoxy resin is added to the carbon fiber to which the above treating agent is attached.
100 g (same Epicoat 828 as above), boron trifluoride monomethylamine 5 g, and methyl ethyl ketone 25
A unidirectional prepreg was prepared by impregnating a resin solution of g and semi-curing at 120 ° C. This prepreg was laminated in a mold, pressure-molded at 170 ° C. for 1 hour, and then cured and molded according to a conventional method to obtain CFRP having a fiber-containing volume ratio of 60%.

Table 1 shows the fluff and yarn breakage evaluation results for each carbon fiber to which the treatment agent was attached, and the ILSS measurement results for each CFRP.

Examples 5 to 9 and Comparative Examples 4 to 7 Epoxy resin (the same Epicoat 828 as above), 1,4-phenylene-bis- (2-oxazoline), oleyl oleate, and methyl ethyl ketone were mixed in the proportions shown in Table 2. Then, it was dissolved to prepare a treatment liquid. Then, immerse the carbon fiber in this treatment liquid, squeeze it so that the amount of solids deposited becomes around 1.3%, and air-dry at room temperature, then 90 ° C ×
Heat treatment was performed for 20 minutes and further at 160 ° C. for 10 minutes to obtain carbon fibers to which the treatment agent was attached.

Thus, the carbon fibers to which the treating agent is attached are added to Examples 1 to 4
In the same manner as in, the resin liquid was impregnated, semi-cured to prepare a prepreg, and further cured and molded to obtain CFRP.

Table 2 shows the fluff and yarn breakage evaluation results for each carbon fiber to which the treating agent was attached, and the ILSS measurement results for each CFRP.

-Examples 10 to 12 and Comparative Example 8 The carbon fiber coated with the treating agent in Examples 5 to 7 and Comparative Example 5 was used, and an unsaturated polyester resin (trade name: Polymer 8225p, Takeda Chemical Industries, Ltd.) was used instead of the epoxy resin. CFRP was obtained in the same manner as in Examples 5 to 7 and Comparative Example 5, except that

 The results of ILSS measurement for each CFRP are shown in Table 3.

<Effects of the Invention> As is clear from the results of each table, the present invention described above has the effect that the production or processing characteristics of carbon fibers can be improved and the strength characteristics of the molded product can also be improved. There is.

Claims (1)

(57) [Claims] 1. The following A component and B component are A component / B component =
A surface treatment agent for carbon fibers, which is contained in a ratio of 95/5 to 40/60 (weight ratio). Component A: Phenol-based epoxy resin and / or aromatic nitrogen-based epoxy resin B-component: 2 having a boiling point of 140 ° C. or higher represented by the following general formula
-Oxazoline compounds of general formula: (However, X is absent, or a divalent aliphatic or aromatic hydrocarbon group)