JPH09105080A - Surface-treated carbon fiber and carbon fiber-reinforced resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition markedly improved in mechanical strength by use of a matrix resin and surface-treated carbon fibers having an exothermic peak within a specific temperature range, and capable of making composite material having stable mechanical strength even at relatively high temperatures. SOLUTION: First, carbon fiber bundles with the number of oxygen atoms being 0.1-1 per carbon atom on the fiber surface is immersed in a surface treating agent liquid prepared by using a polyurethane-based resin and emulsifier and then dried to produce carbon fibers having an exothermic peak within a temperature range of 150-350 deg.C. The wettability of the carbon fibers is improved by admixing the above surface treating agent with 0.01-50wt.% of an organic acid such as acetic acid and/or inorganic acid such as hydrochloric acid. The other objective composition is obtained by using 3-70wt.% of the above surface-treated carbon fibers and 97-30wt.% of at least one kind of matrix resin selected from among thermoplastic polyimides, polyaryl ether ketones and polyethersulfones. A molded product is obtained by molding the above composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a carbon fiber having a surface treatment agent for carbon fiber adhered thereto and a carbon fiber as a reinforcing material for obtaining a carbon fiber reinforced resin composite material having excellent mechanical properties. The present invention relates to a carbon fiber reinforced resin composition, a molded article made of the resin composition, and the surface treatment agent.

[0002]

2. Description of the Related Art Carbon fiber reinforced resin is far superior to non-reinforced resin in strength, rigidity and dimensional stability.
It is widely used in various industrial fields such as office equipment, automobile fields, aircraft materials, and electric / electronic material fields. However, the carbon fiber originally has poor adhesiveness with the matrix resin by itself, and the composite of the carbon fiber as it is with the matrix resin improves the characteristics to some extent as compared with the matrix resin alone, but the degree of improvement is insufficient and the carbon fiber It is hard to say that the characteristics are used effectively. Generally, the characteristics of the carbon fiber reinforced resin are governed by the carbon fiber content, but it is also greatly influenced by the adhesiveness at the interface between the fiber and the resin. That is, unless the fibers and the resin are bonded to each other with appropriate strength, proper stress cannot be transmitted, and the desired mechanical properties of the composite material cannot be obtained.
Therefore, improve the adhesion between carbon fiber and matrix resin,
As a means for improving the properties of the obtained composite material, there is a surface treatment method called so-called sizing treatment in which the surface of the carbon fiber is coated with an effective substance.

For example, the method of surface treatment using an epoxy resin as described in JP-A-61-252371 is a method that has been known for a long time and is widely used as a surface treatment agent for carbon fibers. ing. In addition to the epoxy resin, JP-A-58-126375 discloses a method of surface-treating carbon fiber with a polyurethane resin. Further, JP-A-4-82969 describes a method of using a water-based polyurethane resin obtained by mixing and emulsifying a polyurethane resin in water as a surface treatment agent.

However, the above-mentioned JP-A-61-2523
Carbon fiber surface-treated with an epoxy resin as described in Japanese Patent Publication No. 71 makes it easy to open the fiber by softening the epoxy resin when contacting with a resin heated in a hopper for drying etc. Often makes driving difficult. Since epoxy resin has poor heat resistance, when a so-called super engineering plastic (hereinafter referred to as super engineering plastic) such as polyimide or polyether ether ketone (hereinafter referred to as PEEK) is used as a matrix resin, the surface of Since the processing temperature is higher than the decomposition temperature of the treatment agent, the surface treatment agent is decomposed during the processing, and there is a problem that the function as the surface treatment agent cannot be sufficiently fulfilled.

The method of using the polyurethane resin obtained by the method described in JP-A-63-152468 as a surface treatment agent is a method for solving the above problems,
Probably because the polyurethane resin has a high molecular weight, the fluidity is poor, and it is difficult to uniformly coat the carbon fibers. In addition, since an organic solvent is used for surface treatment of polyurethane, disaster prevention during molding and product use
There are still problems with safety and hygiene, and it is hard to say that this is a sufficient method.

The method of mixing and emulsifying a polyurethane resin in water as described in JP-A-4-82969 does not use an organic solvent, so problems in disaster prevention, safety and hygiene can be solved. However, even if a polyurethane surface treatment agent such as the above method is used, polyimide or PE
When a so-called super engineering plastic such as EK is used in a matrix resin system, the processing temperature is higher than that of general-purpose resins and general-purpose engineering plastics. is not. As described above, each method has advantages and disadvantages.

[0007]

The object of the present invention is to provide a carbon fiber which can be used for heat-resistant applications, is excellent in safety, and can provide a composite material having stable and high-strength mechanical properties even at high temperatures, and a carbon fiber. And a matrix resin.

[0008]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that carbon fibers surface-treated with a surface-treating agent comprising a polyurethane resin and an emulsifier have a specific heat generation at 150 to 350 ° C. It was found that the presence of the exothermic peak is essential for developing high-strength physical properties when a carbon fiber having a peak is mixed with a matrix resin to form a composite material, and the present invention has been completed. It was

That is, the present invention is: 1) a carbon fiber which is treated with a surface treating agent comprising a polyurethane resin and an emulsifier and has an exothermic peak at 150 ° C to 350 ° C, 2) the above surface treating agent The carbon fiber before being surface-treated with 1. has a number of oxygen atoms in the range of 0.1 to 1 with respect to 1 carbon atom on the surface of the carbon fiber, 3) 0.01 to 50 wt% of an organic acid and / or an inorganic acid is contained in the surface treatment agent, and the carbon fiber according to the above 1) is described. 4) The carbon fiber according to 1) to 3) above. Carbon fiber obtained by heat-treating carbon fiber at a temperature equal to or higher than the exothermic peak of the carbon fiber, 5) Carbon fiber 3 to 70 described in 1) to 4) above.
Carbon fiber reinforced resin composition containing a composition consisting of wt% and matrix resin 97 to 30 wt%, 6) The matrix resin is at least one selected from thermoplastic polyimide, polyaryl ether ketone, and polyether sulfone. The carbon fiber reinforced resin composition according to 5) above, 7) a molded article molded from the carbon fiber reinforced resin composition according to 5) above, 8) a surface treatment agent comprising a polyurethane resin and an emulsifier, the surface being During the treatment, the organic acid and / or the inorganic acid is reduced to 0.
The surface treating agent is characterized by containing 01 to 50% by weight.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The characteristic feature of the carbon fiber obtained in the present invention is that the carbon fiber surface-treated with a surface treatment agent comprising a polyurethane resin and an emulsifier has a specific exothermic peak at 150 to 350 ° C. . The temperature of the exothermic peak is 150 to 150 depending on the type of the raw material monomer of the polyurethane resin, the type of the blocking agent for the isocyanate group at the end, the type of the emulsifier, the type of carbon fiber and the difference in the functional groups on the surface.
It will be slightly different in the range of 350 ° C.

The reason why the exothermic peak appears is not certain, but it is considered that the functional group such as carboxy group on the carbon fiber surface chemically reacts with the polyurethane resin. The amount of functional groups on the carbon fiber is large, or the presence of an acid accelerates the decomposition of the urethane bond, and an isocyanate group is generated, whereby the functional group on the carbon fiber chemically reacts with the polyurethane resin, It is considered that the surface of the fiber is covered more and the wettability is improved.

The method of measuring the exothermic peak in the present invention is as follows:
It is a commonly used thermal analysis method, and examples thereof include a differential thermal analysis method (DTA method) and a differential scanning calorimetry method (DSC method).

The polyurethane resin used in the present invention is a resin synthesized from polyisocyanate and polyol as raw material monomers. As polyisocyanate,
It is a conventionally known aromatic, aliphatic or alicyclic polyisocyanate, which is represented by the general formula (1) (formula 1).

[0014]

Embedded image (R ₁ represents an n-valent aromatic, aliphatic or alicyclic organic group having 1 to 20 carbon atoms. N is an integer of 2 or more.) Specifically, for example, 2,4-tri Diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 1,6-hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, xylylene diisocyanate And polyisocyanates such as tetramethylxylylene diisocyanate, and burette compounds and isocyanurate compounds of these isocyanates. You may use these individually or in mixture of 2 or more types. The polyol is a polyhydric alcohol having two or more hydroxyl groups and is represented by the general formula (2) (formula 2).

[0015]

Embedded image (R ₂ represents an n-valent aromatic, aliphatic or alicyclic organic group having 1 to 20 carbon atoms. N is an integer of 2 or more.) Specifically, for example, ethylene glycol, 1, 2-propylene glycol, 1,3-butylene glycol, 1,
4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, 3-methyl-1,5-pentadiol, polycarbonate diol, neopentyl glycol, alkylene oxide adduct of bisphenols, alkylene of hydrogenated bisphenols Glycols having two alcoholic hydroxyl groups such as oxide adducts, polyether diols such as polyethylene glycol, polypropylene glycol, polyoxytetramethylene glycol, polyethylene adipate, polypropylene adipate, polypropylene adipate, polybutylene adipate, polytetramethylene adipate Polyester such as polypentamethylene adipate, polyhexamethylene adipate, polycaprolactanediol Diols, trimethylol ethane, trimethylol propane, glycerin, polyhydric alcohols such as pentaerythritol. You may use these individually or in mixture of 2 or more types. Further, the polyurethane may be partially substituted with polyester. Polyester is a resin synthesized from a diol component and a dicarboxylic acid component. The diol component is represented by the general formula (3) (formula 3).

[0016]

Embedded image (R ₃ represents an n-valent aromatic, aliphatic or alicyclic organic group having 1 to 20 carbon atoms.) Specifically, for example, ethylene glycol, 1,2-propylene glycol, 1,3- Butylene glycol, 1,
4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, 3-methyl-1,5-pentadiol, polycarbonate diol, neopentyl glycol, alkylene oxide adduct of bisphenols, alkylene of hydrogenated bisphenols Glycols having two alcoholic hydroxyl groups such as oxide adducts, polyether diols such as polyethylene glycol, polypropylene glycol, polyoxytetramethylene glycol, polyethylene adipate, polypropylene adipate, polypropylene adipate, polybutylene adipate, polytetramethylene adipate Polyester such as polypentamethylene adipate, polyhexamethylene adipate, polycaprolactanediol Diol, and the like. You may use these individually or in mixture of 2 or more types. The dicarboxylic acid component is represented by the general formula (4) (formula 4).

[0017]

Embedded image (R ₄ represents an n-valent aromatic, aliphatic or alicyclic organic group having 1 to 20 carbon atoms.) Specifically, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, Examples thereof include phthalic acid and terephthalic acid. You may use these individually or in mixture of 2 or more types. Further, the polyester may be represented by the general formula (5) (formula 5).

[0018]

Embedded image (R ₅ and R ₅ 'represent an aromatic, aliphatic or alicyclic divalent organic group having 1 to 20 carbon atoms.) Specifically, ε-caprolactone and β-methyl-δ-valerolactone Examples thereof include polycaprolactone polyol and polyvalerolactone polyol, which are ring-opening polymers of

As the emulsifier used in the present invention, nonionic surfactants such as polyoxyethylene alkyl ether, glycerin fatty acid ester surfactants, sucrose fatty acid ester surfactants, sorbitan fatty acid ester surfactants. , Propylene glycol fatty acid ester-based surfactants and the like. You may use these individually or in mixture of 2 or more types.

The emulsifier is preferably added in the range of 0.5 to 50% by weight based on the total solid content as the surface treatment agent.
More preferably in the range of 0.6 to 30% by weight, even more preferably in the range of 0.8 to 20% by weight, most preferably 1 to
It is in the range of 10% by weight. If it is less than 0.5% by weight, the effect as an emulsifier is not sufficiently exhibited such that the dispersibility of the surface treatment agent is deteriorated. Further, addition of more than 50% by weight not only does not change the effect but also causes a problem in heat resistance, which may adversely affect the physical properties of the carbon fiber reinforced resin composition using the surface-treated carbon fiber.

In order to obtain the carbon fiber having an exothermic peak at 150 ° C. to 350 ° C. of the present invention, it is also effective to add an organic acid and / or an inorganic acid to the surface treatment agent. By adding acid, the decomposition of urethane bond is promoted,
It is considered that an isocyanate group is generated, the functional group on the carbon fiber chemically reacts with the polyurethane resin, the surface of the carbon fiber is further covered, and the wettability is improved. The organic acid is represented by the general formula (6) (formula 6).

[0022]

Embedded image (R ₆ represents an aromatic, aliphatic or alicyclic n group organic group having 1 to 20 carbon atoms. N is an integer of 1 or more.) Specifically, acetic acid, propionic acid, butane Examples thereof include acids, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, phthalic acid and terephthalic acid.

Examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and the like. These may be used as a mixture. The addition amount of the organic acid and / or the inorganic acid is in the range of 0.01 to 50% by weight in the total amount of the surface treatment agent, preferably 0.05 to
30% by weight, more preferably 0.1 to 10% by weight, most preferably 0.5 to 5% by weight.
If it is less than 0.01% by weight, sufficient effect for decomposing the urethane bond cannot be obtained even if an acid is added, and if it exceeds 50% by weight, the decomposition of the polyurethane-based resin becomes conspicuous and the opposite effect is obtained. . Moreover, a large amount of unreacted acid remains, which may adversely affect the surface treatment.

The carbon fiber used as a raw material in the present invention is not particularly limited, and various known carbon fibers such as rayon, polyacrylonitrile, pitch, lignin,
It can be arbitrarily selected from carbonaceous fibers and graphite fibers produced by using hydrocarbon gas and the like, and metal-coated carbon fibers obtained by coating these with metals.

Furthermore, in order to obtain the carbon fiber used in the present invention having an exothermic peak at 150 ° C. to 350 ° C., one carbon atom on the surface of the carbon fiber is added before the surface treatment of the carbon fiber. Oxygen atom is 0.
It is preferably in the range of 1 to 1 (mol). It is more preferably in the range of 0.20 to 0.8 (mol), and most preferably in the range of 0.25 to 0.5 (mol). The ratio of oxygen atoms to carbon atoms represents the amount of functional groups on the carbon fiber surface. The ratio of oxygen atoms to carbon atoms is 0.1
If it is less than 1, the mechanical properties are not sufficient especially at high temperature, and if it exceeds 1, the effect does not change so much, and the strength of the carbon fiber itself decreases.

In the present invention, the method for applying the surface treatment agent to the carbon fiber may be any method as long as it can be uniformly applied, such as a dipping method, a spray method and a rotating roller method. The water drying method after application is also hot air drying. Method, hot roller drying method, or the like. The drying temperature is preferably in the range of 100 to 200 ° C. at which water can be efficiently evaporated. The drying time is usually in the range of 0.1 to 30 hours. Furthermore, the heat treatment may be performed at a temperature of an exothermic peak or higher. The temperature of the exothermic peak varies slightly in the range of 150 to 350 ° C. depending on the raw material monomer of the polyurethane resin, the type of blocking agent for the isocyanate group at the end, the type of emulsifier, and the like. The upper limit of the heat treatment temperature may be within the range where the surface treatment agent is not extremely deteriorated, and is preferably up to about 350 ° C. The range is more preferably 180 to 300 ° C, and most preferably 200 to 280 ° C. If the temperature is lower than 150 ° C, there is no difference in the physical properties even after heat treatment, and if the temperature exceeds 350 ° C, the surface treatment agent may deteriorate. The heat treatment time is usually in the range of 0.1 to 30 hours.

The amount of the surface treatment agent adhered to the carbon fibers in the present invention is in the range of 0.1 to 10% by weight, preferably 1 to 5% by weight, more preferably 2 based on the total weight of the carbon fibers.
Is in the range of 4%. If the amount is less than 0.1% by weight, the carbon fibers cannot be provided with sufficient bundling properties, and the carbon fibers are opened in a post-processing step, for example, a step of forming a chopped fiber, mixing it with a resin, and forming a pellet, which is not practical. On the other hand, if the adhesion amount exceeds 10% by weight, the fiber strands to which the sizing agent is applied become too rigid, and continuous winding on a bobbin becomes impossible, which is not practical. In addition, the sizing property is too strong, resulting in poor dispersion during molding, which may rather reduce the strength.

As the resin used as the matrix resin in the present invention, for example, the following formulas (A), (Chem. 7), (B)
A thermoplastic polyimide having a repeating structural unit of (Chemical Formula 8) or (C) (Chemical Formula 9), a polyether ether ketone having a repeating structural unit of the following Formula (D) (Chemical Formula 11),
Similarly, a polyether ketone of the following formula (E)
Polyaryletherketone-based resins such as polyetherketoneetheretherketone of the following formula (F) (Chemical formula 13), polyether sulfone of the following formula (G) (Chemical formula 14),
Polyetherimide of the following formula (F) (Chemical formula 15), aromatic polysulfone of the following formula (I) (Chemical formula 16), and the following formula (J)
Aromatic polyphenylene sulfide of (Chemical Formula 17), aromatic polyether nitrile of the following formula (K) (Chemical Formula 18), polycarbonate, polyamide, polyphenylene ether,
Examples thereof include polyoxymethylene, polyester, polyphenylene sulfide, polyolefin, ABS resin, polyurethane, phenol resin and epoxy resin. These may be used as a mixture. All of these matrix resins are known, and commercially available ones can be used. Preferred are polyaryletherketone resins such as thermoplastic polyimide, polyetheretherketone, polyetherketone, polyetherketoneetheretherketone, and polyethersulfone.

[0029]

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[0030]

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[0031]

Embedded image (In the above formulas (A), (B) and (C), R ₁ and R ₂ are each hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkoxy group, a halogenated alkyl group, a halogenated alkoxy group or a halogen group. , N is an integer of 0 to 4, X is a direct bond, —O—, —SO ₂ —, —CO—, —C (CH
_{3) 2 -, - C (} CF 3) 2 - or -S-. Also Y
Is one or more groups selected from the group consisting of the following formulas (Formula 10). )

[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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In the present invention, the carbon fiber reinforced resin composition contains 3 to 70% by weight of the carbon fiber treated as described above. More preferably 5 to 60% by weight, further preferably 10 to 50% by weight, most preferably 20 to 4%.
The range is 0% by weight. If the content of carbon fibers in the resin composition is less than 3% by weight, the effect as a reinforcing material is small, and if it exceeds 70% by weight, the moldability is remarkably deteriorated, which is not preferable.

If necessary in the present invention, it is possible to mix the filler in an amount that does not impair the object of the invention.
As the filler, carbon black, graphite, carborundum, silica stone powder, molybdenum disulfide, wear resistance improving material such as fluororesin, glass fiber, aromatic polynoamide fiber, alumina fiber, boron fiber, silicon carbide fiber,
Potassium titanate whiskers, aluminum borate whiskers, carbon whiskers, asbestos, metal fibers,
Reinforcing material such as ceramic fiber, flame retardant improving material such as antimony trioxide, magnesium carbonate and calcium carbonate, tracking resistance improving material such as asbestos, silica and graphite, acid resistance improving material such as barium sulfate, silica and calcium metasilicate , Iron powder, zinc powder, aluminum powder, copper powder, etc., thermal conductivity improving material, other polybenzimidazole resin, silicon resin, glass beads, talc, diatomaceous earth,
Alumina, Silasbaln, hydrated alumina, metal oxides,
There is no problem even if a colorant, a plasticizer, etc. are added.

The carbon fiber surface-treated as described above is cut into a length of 1 to 150 mm to form chopped strands, which is dry-blended with a desired matrix resin such as polyimide or PEEK and then melted in an extruder. -After extrusion while kneading, pellets can be obtained by cutting into a predetermined length. The pellet can be obtained by a generally known molding method, that is, compression molding, injection molding, and extrusion molding to obtain a desired molded body. Further, the carbon fibers obtained in the present invention may be aligned in one direction and then impregnated with a heat resistant thermoplastic resin by a usual method to obtain a prepreg. Examples of the impregnation method include melt impregnation disclosed in JP-A-1-121363. The prepreg thus obtained can then be cut to a certain length, laminated so that the fibers are oriented in a predetermined direction, and then a molded body can be obtained by a usual method such as hot pressing.

[0044]

The present invention will be described below with reference to examples, but the present invention is not limited thereto. Polyurethane-based resin synthesis example 1 6,6-hexamethylene diisocyanate 67.2 g
(0.4 mol, 90.0 g of 1,4-butanediol
(1.0 mol), 3-methyl-1,5-pentadiol 31.2 g (0.3 mol), adipic acid 129.6 g
(0.9 mol) and 700 g of methyl ethyl ketone were placed in a four-necked flask and stirred at 80 ° C. for 8 hours. Next, the reaction product and 30 g of polyethylene glycol having a benzene ring introduced at the terminal as an emulsifier were added and mixed in water to emulsify. Then, the methyl ethyl ketone was removed by evaporation to obtain an aqueous polyurethane resin having a polymer concentration of about 30% by weight.

Polyurethane Resin Synthesis Example 2 69.6 g of 2,4-tolylene diisocyanate as a raw material
(0.4 mol), 1,4-butanediol 90.0 g
(1.0 mol), bisphenol A 69.6 g (0.3
Mol) and 129.6 g (0.9 mol) of adipic acid were used and the same experiment as in Synthesis Example 1 was carried out to obtain an aqueous polyurethane resin having a polymer concentration of about 30% by weight.

Polyurethane Resin Synthesis Example 3 The raw material was 1,6-hexamethylene diisocyanate 67.
An experiment was performed in the same manner as in Synthesis Example 1 except that 2 g (0.4 mol) and 40 g (0.02 mol) of adipate were used to obtain an aqueous polyurethane resin having a polymer concentration of about 30% by weight.

Synthesis Example 4 of Polyurethane Resin As raw material, 1,6-hexamethylene diisocyanate 33.
6 g (0.2 mol), 1,4-butanediol 90.0
g (1.0 mol), 3-methyl-1,5-pentadiol 31.2 g (0.3 mol), adipic acid 129.6 g
An experiment was conducted in the same manner as in Synthesis Example 1 except that (0.9 mol) was used to obtain an aqueous polyurethane resin having a polymer concentration of about 30% by weight.

Polyurethane Resin Synthesis Example 5 The raw material was 1,6-hexamethylene diisocyanate 67.
An experiment was conducted in the same manner as in Synthesis Example 1 except that 2 g (0.4 mol) and 20 g (0.01 mol) of adipate were used to obtain an aqueous polyurethane resin having a polymer concentration of about 30% by weight.

Synthesis Example 6 of Polyurethane Resin Caprolactane glycol (molecular weight 2,000) was used as a raw material.
200 g (0.1 mol), trimethylolpropane 40
An experiment was conducted in the same manner as in Synthesis Example 1 except that g (0.3 mol) and diphenylmethane diisocyanate (0.4 mol) 100 g were used to obtain an aqueous polyurethane resin having a polymer concentration of about 30% by weight.

Polyurethane Resin Synthesis Example 7 0.0284 g (0.1% of solid content) of the aqueous polyurethane resin having a polymer concentration of about 30% by weight obtained in Synthesis Example 4 was obtained.
(01% by weight) adipic acid was added to prepare a surface treatment agent.

Synthetic Example 8 of Polyurethane-Based Resin 0.0142 g of the water-based polyurethane resin having a polymer concentration of about 30% by weight obtained in Synthetic Example 4 (0.
(005 wt%) adipic acid was added to prepare a surface treatment agent.

Polyurethane Resin Synthesis Example 9 142 g (50% by weight of solid content) of adipic acid was added to the aqueous polyurethane resin having a polymer concentration of about 30% by weight obtained in Synthesis Example 4 to prepare a surface treatment agent. Prepared.

Polyurethane Resin Synthesis Example 10 Surface treatment by adding 170.4 g (60% by weight to solid content) of adipic acid to the aqueous polyurethane resin having a polymer concentration of about 30% by weight obtained in Synthesis Example 4. The agent was prepared.

Example 1 The polyurethane resin obtained in Synthesis Example 1 had a solid content of 2.
Diluted with water to 5% by weight. A polyacrylonitrile-based carbon fiber (manufactured by Toho Rayon Co., Ltd., trade name HTA, filament number 1) in a polyurethane resin solution obtained by dilution.
A bundle of 2,000 pieces, the number of oxygen atoms on the carbon fiber surface / the number of carbon atoms = 0.23) was immersed in the above polyurethane resin solution at a speed of 60 m / min and dried at 100 ° C. for 3 hours. It was At this point, when the carbon fiber surface-treated with the polyurethane resin was analyzed by DTA, an exothermic peak was observed at 252 ° C. The DTA used for the analysis is the following device. Apparatus: Seiko Denshi Kogyo Co., Ltd. SSC5200 Thermal Analysis System TG / DTA320 Temperature rising rate: 10 ° C./min Atmosphere: Air.

The dried carbon fiber was further heated at 250 ° C. for 3 hours.
Heat treatment was performed for an hour. The carbon fiber obtained is then 3 m long
chopped strands by cutting into m, and 30% by weight of the strands and AURUM45 which is a thermoplastic polyimide
0 (Mitsui Toatsu Chemical Co., Ltd .; trademark) 70% by weight, after dry blending, extrusion temperature 41 with a 40 mm diameter extruder
An operation of extruding while melting and kneading at 0 ° C. was carried out to obtain a uniformly mixed pellet. Next, a dumbbell test piece was prepared from the above homogeneously blended pellets under the temperature conditions of a cylinder temperature of 400 ° C. and a mold temperature of 210 ° C. using an ordinary injection molding machine, and the tensile strength was measured at a tensile speed of 5 mm / min. 27.6k
g / cm ² .

Example 2 An experiment was conducted in the same manner as in Example 1 except that the polyurethane resin synthesized in Synthesis Example 2 was used. The exothermic peak in the DTA analysis of the carbon fiber before heat treatment was 348 ° C., and the tensile strength of the dumbbell test piece was measured and found to be 27.3 kg / cm ² .

Example 3 An experiment was conducted in the same manner as in Example 1 except that the polyurethane resin synthesized in Synthesis Example 3 was used. The exothermic peak in the DTA analysis of the carbon fiber before heat treatment was 159 ° C., and the tensile strength of the dumbbell test piece was measured and found to be 27.1 kg / cm ² .

Example 4 The same experiment as in Example 1 was conducted using PEEK150P (manufactured by ICI) as a matrix resin. The molding temperature is 400 ° C and the mold temperature is 190 ° C. When the tensile strength of the dumbbell test piece was measured, it was 25.9 kg / cm ^2.
Met.

Example 5 The same experiment as in Example 1 was conducted using PES (manufactured by ICI) as a matrix resin. Molding temperature is 360
C., mold temperature is 150.degree. The tensile strength of the dumbbell test piece was measured and found to be 25.9 kg / cm ² .

Example 6 An experiment was conducted in the same manner as in Example 1 except that the polyurethane resin synthesized in Synthesis Example 7 was used. The exothermic peak in the DTA analysis of the carbon fiber before heat treatment was 255 ° C., and the tensile strength of the dumbbell test piece was measured and found to be 27.4 kg / cm ² .

Example 7 An experiment was conducted in the same manner as in Example 1 except that the polyurethane resin synthesized in Synthesis Example 9 was used. The exothermic peak in the DTA analysis of the carbon fiber before heat treatment was 255 ° C., and the tensile strength of the dumbbell test piece was measured and found to be 26.8 kg / cm ² .

Example 8 Polyacrylonitrile-based carbon fiber (manufactured by Toho Rayon Co., Ltd., trade name HTA, number of filaments 12,000) was used as carbon fiber.
Book, number of oxygen atoms on carbon fiber surface / number of carbon atoms =
An experiment was conducted in the same manner as in Example 1 except that 0.10) was used. The exothermic peak in the DTA analysis of the carbon fiber before heat treatment was 249 ° C., and the tensile strength of the dumbbell test piece was measured and found to be 27.2 kg / cm ² .

Example 9 Carbon fiber was polyacrylonitrile-based carbon fiber (trade name: HTA, manufactured by Toho Rayon Co., Ltd., filament number: 12,000).
Book, number of oxygen atoms on carbon fiber surface / number of carbon atoms =
An experiment was conducted in the same manner as in Example 1 except that (1.00) was used. The exothermic peak in the DTA analysis of the carbon fiber before heat treatment was 260 ° C., and the tensile strength of the dumbbell test piece was measured and found to be 27.9 kg / cm ² .

Comparative Example 1 An experiment was conducted in the same manner as in Example 1 except that the polyurethane resin synthesized in Synthesis Example 4 was used. No exothermic peak was observed in the DTA analysis of the carbon fiber before heat treatment, and the tensile strength of the dumbbell test piece was measured to be 18.6 kg / cm.
² was lower than that of Example 1.

Comparative Example 2 An experiment was conducted in the same manner as in Example 1 except that the polyurethane resin synthesized in Synthesis Example 5 was used. No exothermic peak was observed in the DTA analysis of the carbon fiber before heat treatment, and the tensile strength of the dumbbell test piece was measured to be 19.0 kg / cm.
² was lower than that of Example 2.

Comparative Example 3 An experiment was conducted in the same manner as in Example 1 except that the polyurethane resin synthesized in Synthesis Example 6 was used. No exothermic peak was observed in the DTA analysis of the carbon fiber before heat treatment, and the tensile strength of the dumbbell test piece was measured to be 18.2 kg / cm.
² was lower than that of Example 3.

Comparative Example 4 An experiment was conducted in the same manner as in Example 4 except that the polyurethane resin synthesized in Synthesis Example 4 was used. No exothermic peak was observed in the DTA analysis of the carbon fiber before heat treatment, and the tensile strength of the dumbbell test piece was measured to be 17.3 kg / cm.
² was lower than that of Example 4.

Comparative Example 5 An experiment was performed in the same manner as in Example 5 except that the polyurethane resin synthesized in Synthesis Example 4 was used. No exothermic peak was observed in the DTA analysis of the carbon fiber before heat treatment, and the tensile strength of the dumbbell test piece was measured to be 15.9 kg / cm.
² was lower than that of Example 5.

Comparative Example 6 An experiment was conducted in the same manner as in Example 1 except that the polyurethane resin synthesized in Synthesis Example 8 was used. No exothermic peak was observed in the DTA analysis of the carbon fiber before heat treatment, and the tensile strength of the dumbbell test piece was measured to be 18.8 kg / cm.
² was lower than that of Example 6.

Comparative Example 7 An experiment was conducted in the same manner as in Example 1 except that the polyurethane resin synthesized in Synthesis Example 10 was used. No exothermic peak was observed in the DTA analysis of the carbon fiber before heat treatment, and the tensile strength of the dumbbell test piece was measured to be 18.7 kg / cm ^2.
It was lower than that of Example 7.

Comparative Example 8 Polyacrylonitrile-based carbon fiber (manufactured by Toho Rayon Co., trade name HTA, number of filaments 12,000) was used as carbon fiber.
Book, number of oxygen atoms on carbon fiber surface / number of carbon atoms =
An experiment was conducted in the same manner as in Example 1 except that 0.08) was used. The exothermic peak in the DTA analysis of the carbon fiber before the heat treatment was 251 ° C., and the tensile strength of the dumbbell test piece was measured to be 23.9 kg / cm ^2, which was slightly lower than that in Example 1.

Comparative Example 9 Polyacrylonitrile-based carbon fiber (manufactured by Toho Rayon Co., Ltd., trade name HTA, filament number 12,000) was used as the carbon fiber.
Book, number of oxygen atoms on carbon fiber surface / number of carbon atoms =
An experiment was conducted in the same manner as in Example 1 except that 1.05) was used. The exothermic peak in the DTA analysis of the carbon fiber before heat treatment was 260 ° C., and the tensile strength of the dumbbell test piece was measured to be 25.6 kg / cm ^2, which was slightly lower than that in Example 1. Table 1 shows the relationship between the above-mentioned synthesis examples and Examples and Comparative Examples, Table 2 shows the results of Examples, and Table 3 shows the results of Comparative Examples.

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[Table 1]

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[Table 2]

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[Table 3]

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EFFECTS OF THE INVENTION The surface-treated carbon fiber according to the present invention can be significantly improved in mechanical strength and the like even when it is super engineering plastic such as polyimide by filling it with a matrix resin, and is stable even at high temperature. It has excellent mechanical strength and has great industrial significance.

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Claims (8)

[Claims] 1. A carbon fiber which is treated with a surface-treating agent comprising a polyurethane resin and an emulsifier and has an exothermic peak at 150 ° C. to 350 ° C. 2. The carbon fiber before being surface-treated with the above surface-treating agent has an oxygen atom number in the range of 0.1 to 1 with respect to 1 carbon atom on the surface of the carbon fiber. The carbon fiber according to claim 1. 3. The carbon fiber according to claim 1, wherein the surface treatment agent contains 0.01 to 50% by weight of an organic acid and / or an inorganic acid. 4. A carbon fiber obtained by heat-treating the carbon fiber according to any one of claims 1 to 3 at a temperature equal to or higher than the exothermic peak of the carbon fiber. 5. A carbon fiber reinforced resin composition containing a composition comprising 3 to 70% by weight of the carbon fibers according to claim 1 to 4 and 97 to 30% by weight of a matrix resin. 6. The carbon fiber reinforced resin composition according to claim 5, wherein the matrix resin is at least one selected from thermoplastic polyimide, polyaryl ether ketone, and polyether sulfone. 7. A molded product molded from the carbon fiber reinforced resin composition according to claim 5. 8. A surface treatment agent comprising a polyurethane resin and an emulsifier, wherein the surface treatment agent contains 0.01 to 50% by weight of an organic acid and / or an inorganic acid.