JPS6047956B2 - Carbon fiber sizing method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for sizing carbon fibers.

Conventionally, carbon fiber has been used as a composite material in a wide range of fields, such as aviation and space materials, and sports equipment such as fishing rods, tennis rackets, and golf shafts, due to its excellent mechanical properties such as specific strength and specific modulus. However, carbon fibers or graphite fibers are inherently rigid and brittle, and have poor bending resistance and abrasion resistance, so they tend to generate fuzz during the manufacturing process or higher-order processing process, and even break. In addition, the carbon fibers generally have poor adhesion to the matrix.

Therefore, various sizing agents are usually added to carbon fibers, and this sizing gives the carbon fibers cohesiveness, improves bending resistance and abrasion resistance, and improves adhesion to the matrix. is normal. As these conventional sizing agents for carbon fibers, organic solvent-based epoxies are used because of their uniform adhesion to carbon fibers, solution stability of the sizing agent, and compatibility and adhesion with matrices, especially various matrix resins. Although sizing agents based on organic solvents or polyesters are generally used, these sizing agents based on organic solvents are not preferred from the viewpoint of workability in the sizing process, particularly from the viewpoint of environmental hygiene and disaster prevention such as fire.

The present inventors have previously discovered that an organic solvent solution of an epoxy resin containing a polyalkylene glycol derivative represented by the general formula (1) or (■) as the organic solvent-based sizing agent has the advantage of adhesion to the matrix resin of carbon fibers. In addition to significantly improving the physical properties of the composite, the authors discovered and proposed ways to improve the handling properties and high-cut processing performance of the carbon fiber.

However, as a result of further investigation, we found that this sizing agent has limitations in terms of safety, health, and disaster prevention, which are the essential shortcomings of the organic solvent-based sizing agent. ) is difficult.

Therefore, when applying the sizing agent, safety and health and disaster prevention measures are required, and the carbon fibers immediately after firing must be wound onto a bobbin or the like and sized in a separate process, making the work complicated. Moreover, in this case, the carbon fibers are mechanically damaged during the winding of the carbon fibers and the drawing process of the carbon fibers in which the sizing agent is applied, and the sizing agent is affected by the sizing agent, such as the generation of fuzz and reduced cohesiveness. The inventors discovered that it is difficult to make carbon fibers exhibit excellent performance to the fullest, and conducted extensive research to discover the present invention. That is, the object of the present invention is to take advantage of the excellent sizing performance for carbon fibers of the epoxy sizing agent containing the compound represented by the general formula (1) or (■), especially the adhesion to matrix resin, and to The purpose is to provide a sizing method that does not cause problems in the sanitary environment and disaster prevention and safety during organic solvent-based sizing treatment.Other purposes are to provide a sizing method that does not cause problems in the sanitary environment and disaster prevention safety. To provide a sized carbon fiber that can be converted into a high-quality, high-performance prepreg or composite with little fuzz, yarn breakage, etc. when converting the carbon fiber into a prepreg or composite. .

As stated in the claims, the object of the present invention is to provide carbon fibers with a small amount of a water-soluble or water-dispersible polymer as a sizing agent in advance and to bind them together. This can be achieved by a carbon fiber sizing method in which an organic solvent-based sizing agent is then applied. The carbon fibers of the present invention are prepared by using various types of fibers such as acrylic, pitch, and cellulose fibers as a front drive body, and subjecting them to disaster resistance treatment using 7 known methods, and then heating them at 800 to 2800°C in an inert gas atmosphere. This includes both the so-called carbonized type and black flamed type fired nearby, but especially those whose surfaces have been oxidized have a remarkable effect. A feature of the present invention is that in order to fully exhibit the excellent sizing performance for carbon fibers of the epoxy resin composition containing the polyalkylene glycol derivative represented by the general formula (1) or (■), a small amount of The point is to apply an aqueous sizing resin solution and/or an aqueous dispersion to carbon fibers and bundle them.

Such sizing aqueous solutions and aqueous dispersions are resins that exhibit binding properties for carbon fibers and have chemical affinity or adhesive properties for the organic solvent-based sizing agent, and that contain as little amount as possible. It is preferable that the amount of carbon fibers deposited is sufficient to bundle the carbon fibers and suppress the generation of fuzz.

Such an aqueous sizing resin solution or aqueous dispersion may contain water-soluble or water-dispersible substances such as polyalkylene oxide and its derivatives, polyvinylpyrrolidone and its derivatives, and polyvinyl alcohol, as well as a surfactant. Also included are epoxy resins, unsaturated polyester resins, etc., which can be turned into aqueous dispersions.

Preferably, a sizing agent containing a polyalkylene oxide derivative of an epoxy group-containing compound as an essential component, a sizing agent selected from epoxy resins and/or unsaturated polyester resins, and made water dispersible with a surfactant, etc. are used. Specific examples of the polyalkylene oxide derivatives of the above-mentioned epoxy group-containing compounds include glycidyl ethers of orioxyalkylene ethers such as polyoxyethylene laul glycidyl ether and polyethylene glycol monoglycidyl ether, b) glycerin monomer or diglycidyl ether, and sorbitol polyglycidyl. Examples include glycidyl ethers of polyhydric alcohols such as ethers. That is, these water-soluble 1 or water-dispersible polymers used in the present invention are:
It is water-soluble or water-dispersible, and can be directly sized in the carbon fiber manufacturing process as an aqueous solution or dispersion (on-line), that is, after undergoing a carbonization or graphitization process. The carbon fibers are sufficiently focused through sizing, and the processes after this sizing,
In particular, it has the ability to prevent fuzzing of carbon fibers during the winding process of carbon fibers onto a bobbin and the process of drawing them out from a bobbin, and it substantially improves the sizing properties of the organic solvent-based sizing agent used as the second stage sizing agent for carbon fibers. There is no harm to it.

In order to more fully reflect the excellent sizing performance of organic solvent-based sizing agents on carbon fibers, it is necessary to keep the amount of the water-soluble or water-dispersible polymer attached to the carbon fibers as small as possible. desirably about 0.03 to 1.0% per weight of carbon fiber. The amount is preferably in the range of 0.05 to 0.5% by weight.

Note that the concentration of the solution used here is not particularly limited, but is usually 0.1 to 1. It is better to be within the call volume % range. Further, the sizing method is not particularly limited, and for example, a method of dipping in a solution, a method of applying using a roller, a method of spraying a solution, etc. are used.

Next, a known method such as hot air or infrared drying is used for drying.

In this way, the carbon fibers to which a water-soluble and/or water-dispersible sizing agent has been applied are once wound onto a bobbin. It has excellent effects on

Carbon fibers subjected to such sizing treatment are then
In another step, preferably taking safety precautions, an organic solvent-based sizing agent is further applied.

The organic solvent-based sizing agent has chemical affinity or adhesion to the water-soluble or water-dispersible sizing agent, as well as improving the cohesion, handling, and abrasion resistance of carbon fibers, especially the matrix. A sizing agent with excellent adhesiveness to resin is desirable.

A typical example of such an organic solvent-based sizing agent is an epoxy resin composition containing a polyalkylene glycol derivative represented by the following general formula (1) or (■) as an essential component. . [However, in the above formula, R1 is an alkylene group having 1 to 30 carbon atoms, R2
is an alkyl group having 1 to 30 carbon atoms, R3 and R4 are hydrogen atoms or methyl groups, R5 is a glycidyl group, X is an ether bond (-0-) or an ester bond 0, i/'-03, M, n is an integer from 1 to 20.

] The epoxy resin composition has the general formula (1) or (■
) polyalkylene glycol derivatives (hereinafter referred to as
The epoxy resin constituting the resin composition includes a variety of known epoxy resins, such as glycidyl ether type, glycidyl ester type, glycidyl amine type, fatty acid, etc. Examples include epoxy resins such as the group epoxide type, and preferably glycidyl ether type epoxy resins.

) Such an epoxy resin has a viscosity (at 25 DEG C.) of A1 to 4, preferably D to Y when made into a diethylene glycol monobutyl ether solution with a concentration of 4% by volume.

Here, the above viscosity is Kuniyuki Hashimoto 1 Epoxy Resin 4th Edition (
(Showa 48-1-30) If the viscosity of the epoxy resin is lower than A1 according to the Stokes display value determined by the viscosity measurement method described in Nikkan Kogyo Shimbun, p. 50, the resin composition becomes viscous. During high-order processing of carbon fibers sized with a resin composition, adhesive breakage is likely to occur when unwinding from a bobbin.On the other hand, if the viscosity is higher than 4, the carbon fibers become coarse and hard and fuzz is likely to occur. This is not preferable because it reduces the adhesiveness between the carbon fiber and the matrix resin.

Further, as the derivatives of general formula (1) or (■), the following can be given, for example. That is, as X-R1-X derived from general formula (1), 1,4-butanediol, 1,
These include ethers such as 6-hexanediol, or dibasic organic acid esters such as adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. General formula (■
) Derivatives R2-X include pentyl alcohol, octyl alcohol, nonyl alcohol, lauryl alcohol, myristyl alcohol, pentadecyl alcohol,
Ethers such as cetyl alcohol or fats such as fluoric acid, lauric acid, palmitic acid, stearic acid, behenic acid, and cerotic acid.
υfi-9 acid ester, etc. Engineering 1V02
Examples of the 0V7' include addition reaction products of ethylene oxide or propylene oxide.

R5 is a glycidyl group. The compounding ratio of the derivative of general formula (1) or (■) constituting the epoxy resin composition is 1 to 6 weight percent to 40 to 9 weight percent of the epoxy resin.
, preferably 3 to 9% of the heel weight of the epoxy resin
It is better to be within the range of 4% heel weight.

General formula (1) or (■)! If the blending ratio of the derivative is less than 1%, the effect of preventing fuzzing of carbon fibers will not be sufficient and carbon fibers with good abrasion resistance will not be obtained.On the other hand, if it exceeds 60%, the formula (1) or (■) This is undesirable because the unwinding properties of the obtained carbon fibers deteriorate due to the adhesiveness of the derivative. The amount of the epoxy resin composition used in the present invention attached to the carbon fibers is preferably within the range of 0.1 to 1% by weight, preferably 0.3 to 5% by weight based on the weight of the carbon fibers. .

If the amount of adhesion is less than 0.1%, fuzz and yarn breakage will easily occur during high-order processing processes such as prepreg, woven fabric, filament, and winding. This is not preferable because it deteriorates the penetrating properties and deteriorates the composite properties. Examples of organic solvents used to attach the epoxy resin composition to carbon fibers include aromatic hydrocarbons such as benzene, toluene, and xylene, ketones such as acetone and methyl ethyl ketone, cellosolves, and chloroform. , halogenated hydrocarbons such as trichlene, etc.

Further, the concentration of the organic solvent solution of the resin composition is 0.5-3.
It is preferable to keep the amount of rutting in the range of 1 to 2 %, and if it exceeds 30%, it is not preferable in terms of impregnation and uniform adhesion to carbon fibers.

In addition, if it is lower than 0.5%, a large amount of solvent will be used to achieve the desired amount of adhesion, which may cause health and safety concerns.
This is disadvantageous in terms of cost and cost. The method of applying the organic solvent solution of the epoxy resin composition used in the present invention to the carbon fibers is not particularly limited, and examples thereof include immersion in the solution, application using a roller, and spraying the solution. methods etc. are used.

Carbon fibers coated with an organic solvent-based sizing agent are dried, but if the drying temperature exceeds 250°C, thermal deterioration of the resin composition tends to occur, so the drying temperature is usually 100 to 250°C.
It is best to dry it.

When an organic solvent-based sizing agent is applied to carbon fibers in this way, the fuzz suppression and binding effects of the water-soluble and/or water-dispersible polymers applied in advance are promoted, and its excellent handling properties promote In addition to significantly reducing problems caused by fuzz and thread breakage during high-order processing, the original sizing performance of organic solvent-based sizing agents,
In other words, the adhesion to carbon fibers can be fully utilized.

According to the present invention, by utilizing an organic solvent-based sizing agent that has excellent adhesion between carbon fibers and matrix resin, it is possible to perform sizing treatment of carbon fibers without causing problems in terms of sanitary environment and disaster prevention and safety. In addition, it is possible to reduce the generation of fluff in the carbon fibers, thereby improving process passability in manufacturing carbon fibers and eliminating problems such as fluff and thread breakage when molding the carbon fibers into prepregs or composites. Furthermore, high-quality, high-performance prepregs and composites can be obtained. Hereinafter, the present invention will be specifically explained with reference to Examples.

The number of surface fuzz, number of abrasion fuzz, bending strength and interlaminar shear strength (ILSS) of the composite were measured using the following measurement methods.

(1) Under a tension of 0.08f per 1 denier on the surface fuzz carbon fiber yarn,
3r! 1. The fiber yarn is run at a yarn speed of 1/min, a laser beam is irradiated from the side at a right angle to the fiber yarn, and the fuzz is detected and counted by a fuzz detection device to determine the number of fuzz/TI. Display in .

(2) Number of fuzz to rub: 50 stainless steel rods with a diameter of 1C)
m! A scraping device was used in which rods were arranged in a zigzag manner so that the rods could be passed in parallel at n intervals and in contact with the surfaces of the rods at a contact angle of 1200°.

This device produces 0.0 per denier carbon fiber yarn.
The fiber yarn was passed under a tension of 8 g on the entry side at a speed of 3 m/min, and a laser beam was irradiated from the side at a right angle to the fiber yarn.
The number of fuzz is detected and counted by a fuzz detection device and displayed as number/Tn. (3) Composite physical properties Bending strength: Measured according to ASTM D-790 Interlaminar shear strength (ILSS) Measured according to ASTM D-2344 Example 1, Comparative example 1 Consisting of a single yarn fineness of 0.6 denier and number of filaments of 6000 In the first step, carbon fiber yarn (Toray manufactured by Toray T3OO) was dipped in an aqueous solution of polyoxyethylene (15 mol) lauryl glycidyl ether with a weight of 0.0%, sized, dried at 190°C, and wound up. Summer.

The amount of adhesion was 0.06% based on the weight of the carbon fibers. Next, as a second step, this yarn is coated with Epicoat 828 (
manufactured by Shell Chemical): Epicote 1004 (manufactured by Shell Chemical)
A 6 wt % ethyl cellosolve solution of a sizing agent containing 1 part by weight of mixed resin and 1 part by weight of polyoxyethylene (15 mol) lauryl glycidyl ether at a mixing ratio of 1:3 was applied, and the mixture was dried at 185 °C and rolled. I carried out the collection.

The total amount of sizing agent deposited was 0.8% based on the weight of the carbon fibers. As a comparative example, the same treatment as in Example 1 was carried out except that the sizing treatment with an aqueous solution of polyoxyethylene (15 mol) lauryl glycidyl ether was not performed.

The amount of sizing agent deposited on this fiber yarn was 0.8% based on the weight of the carbon fibers. Table 1 shows the results of measuring the fluff of each of these carbon fiber yarns.

Example 2 Polyoxyethylenized rice 1,6 for sizing in the first stage
0.0% of glycidyl ether derivative of hexanediol. The treatment was carried out in the same manner as in Example 1, except that the aqueous solution containing 10% slag was used.

The amount of the sizing agent adhered to the weight of the carbon fibers was 0.05% in the first stage, and the total amount of the sizing agent applied after the second stage sizing was 1.0%. Table 2 shows the results of measuring the fluff of the carbon fiber yarn thus obtained. Example 3 In Example 1, in the first step, instead of polyoxyethylene lauryl glycidyl ether, (a) Epicote 82830 (parts by weight) (b) Bisphenol A (7) 2 mol adduct of EO 2 mol Maleic acid 1 .5 mol Sebacic acid 0.5 mol 20 (parts by weight) (C) Polyoxyethylene (70 mol) Styrenated (5 mol) Cumilphenol 5 (parts by weight) (d) Water
The sizing treatment was carried out in the same manner as in Example 1 except that a 0.3% by weight aqueous dispersion of an emulsion consisting of 45(〃) was used, and the first stage adhesion amount was 0.07% and the total adhesion amount was 0.9%. A carbon fiber yarn provided with a sizing agent was obtained.

Fuzz Measurement Example 5 The results are shown in Table 3 for the sizing treated carbon fiber yarn obtained in Example 2.

Example 4, Comparative Example 2 The sizing-treated carbon fiber yarn obtained in Example 1 and, as a comparative example, (a) the same carbon fiber as that used in Example 1, but without any sizing agent applied thereto. Article.

(Exit) The same carbon fiber yarn as that obtained in Comparative Example 1, which was subjected only to the second-stage sizing.

For each yarn, Epicoat 82 was used as the epoxy resin.
F! ? sEpicote 827 (made by Shell Chemical Co., Ltd.) and Chitsonox 221 (made by Chisso Co., Ltd.), unsaturated polyester resins such as Polymer 6409 (made by Takeda Pharmaceutical Co., Ltd.) and Kostar R-280 (made by Mitsui Toatsu Co., Ltd.) as matrices. Carbon fiber reinforced plastic (C
FRP) was produced (fiber volume content was 60% in each case), and the bending strength and I-trap S were measured.

The results are shown in Table 4. Then, a unidirectional CFRP using the same resin as the matrix as in Example 4 was produced (fiber volume content: V1〆1S 110/+0A).
(60%), and the bending strength and 11-SS were measured.

The results are shown in Table 5. Example 6 Using the sizing-treated carbon fiber yarn number obtained in Example 3, a unidirectional CFRP with the same resin as the matrix as in Example 4 was produced (fiber volume content was 60% in both cases), and bent. Intensity and 11-SS were measured.

Claims (1)

[Claims] 1. A carbon fiber is characterized in that a small amount of an aqueous solution and/or dispersion of a water-soluble or water-dispersible polymer is applied as a sizing agent to the carbon fibers, the carbon fibers are bundled, and then an organic solvent-based sizing agent is applied. Carbon fiber sizing method. 2. Claim 1 provides that the organic solvent solution of the sizing agent is an organic solvent for an epoxy resin composition in which a polyalkylene glycol derivative represented by the following general formula (I) or (II) is blended as an essential component. Method for sizing carbon fiber as a solution. ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) [However, in the above formula, R_1 is an alkylene group with 1 to 30 carbon atoms, and R_2 is an alkylene group with 1 to 3 carbon atoms.
0 alkyl group, R_3, R_4 are hydrogen atoms or methyl groups, R_4 is glycidyl group, X is ether bond (-O
-) or an ester bond ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, and m and n are integers from 1 to 20. [3] In claims 1 and 2, the viscosity of the epoxy resin composition is A_1 as the viscosity of a 40% diethylene glycol monobutyl ether solution at 25°C.
A method for sizing carbon fibers that is a mixture of 40 to 99% by weight of an epoxy resin in the range of ~Z_5 and 1 to 60% by weight of a polyalkylene glycol derivative represented by general formula (I) or (II). . 4. The method for sizing carbon fibers according to claim 1, wherein the aqueous solution and/or dispersion of a sizing agent contains a polyalkylene oxide derivative of an epoxy group-containing compound as an essential component.