JP2022022787A - Sizing agent composition - Google Patents

Abstract

To provide a sizing agent composition that gives a carbon fiber bundle capable of forming a carbon fiber-reinforced composite material with excellent bonding between the matrix resin and the carbon fiber and excellent mechanical strength.SOLUTION: A sizing agent composition contains (A) a block isocyanate compound and (B) a compound having at least two unsaturated groups at an end in one molecule. The compound (B) has a calorific value of 100 μJ/mg or more in DTA measurement.SELECTED DRAWING: None

Description

The present invention relates to a sizing agent composition used for carbon fibers.

Since carbon fiber is lightweight, has excellent specific strength and specific elastic modulus, and is also excellent in heat resistance and chemical resistance, carbon fiber can be used as a fiber-reinforced composite material combined with various matrix resins, such as aircraft members and spacecraft members. It is used in many fields such as automobile parts, ship parts, civil engineering and building materials, and sporting goods. With such a wide range of applications, the demand for higher performance of carbon fiber is increasing, and carbon fiber for sports and aircraft in particular is required to have higher strength and higher elastic modulus. There is.

In a composite material using carbon fibers, it is important that the adhesiveness between the carbon fibers and the matrix resin is excellent in order to utilize the excellent properties of the carbon fibers. Originally, carbon fibers do not necessarily have sufficient adhesiveness to the matrix resin, and are subjected to surface oxidation treatments such as chemical oxidation treatment, vapor phase oxidation treatment, and electrolytic oxidation treatment in order to activate the surface thereof.

As the elastic modulus of the carbon fiber increases, the activation reaction of the carbon fiber surface by such surface oxidation treatment tends to be less likely to occur, and improvement of the adhesiveness between the carbon fiber and the matrix resin is required. ..

Since carbon fibers have low elongation and brittle properties, the carbon fiber bundle, which is an aggregate of long carbon fiber fibers, tends to generate fluff due to mechanical friction or the like. Therefore, for the purpose of suppressing the generation of fluff, a sizing treatment for applying a sizing agent to the carbon fiber bundle is performed in the manufacturing process of the carbon fiber reinforced composite material. By this sizing treatment, the carbon fiber bundle can be imparted with a focusing property, and the generation of fluff can be suppressed.

In recent years, studies have been conducted to impart the effect of enhancing the adhesiveness between the carbon fiber and the matrix resin to the sizing treatment, which has been performed for the purpose of suppressing the generation of fluff. In order to improve the adhesiveness between the carbon fiber and the matrix resin, a compound having both a terminal unsaturated group and a polar group has been used as a sizing agent (Patent Document 1), and one molecule of an epoxy group and a vinyl group has been used. It has been proposed to use the compound contained therein (Patent Document 2).

Japanese Unexamined Patent Publication No. 2004-300267 Japanese Unexamined Patent Publication No. 2000-355884

However, even if these compounds are used, the adhesiveness between the carbon fiber and the matrix resin is not sufficiently satisfactory. Therefore, there is a demand for a sizing agent that improves the adhesiveness between the carbon fiber and the matrix resin.

An object of the present invention is a sizing agent composition which improves the drawbacks of the prior art and provides a carbon fiber bundle capable of forming a carbon fiber reinforced composite material having excellent adhesion between a matrix resin and carbon fibers and excellent mechanical strength. In particular, in a composite material using a radically polymerizable thermosetting resin such as unsaturated polyester or vinyl ester resin as a matrix resin, a carbon fiber reinforced composite having excellent adhesion between the matrix resin and carbon fibers is provided. It is an object of the present invention to provide a sizing agent composition which provides a carbon fiber bundle capable of forming a material.

The present invention is a sizing agent composition containing (A) a blocked isocyanate compound and (B) a compound containing at least two unsaturated groups at the terminal in one molecule, wherein (B) the terminal in one molecule. It is a sizing agent composition characterized by having a calorific value of 100 μJ / mg or more in the DTA measurement of a compound containing at least two unsaturated groups.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a sizing agent composition that provides a carbon fiber bundle capable of forming a carbon fiber reinforced composite material having excellent adhesion between a matrix resin and carbon fibers and having excellent mechanical strength, and in particular, A carbon fiber bundle capable of forming a carbon fiber reinforced composite material having excellent adhesion between the matrix resin and carbon fiber in a composite material using a radically polymerizable thermosetting resin such as unsaturated polyester or vinyl ester resin as a matrix resin. A sizing agent composition to be given can be provided.

Hereinafter, the present invention will be described in detail.

[(A) Blocked isocyanate compound]
The blocked isocyanate compound of the sizing agent composition of the present invention is a compound in which the isocyanate group is protected by the blocking agent, and the blocking agent that protects the isocyanate group is separated by heating to generate active isocyanate. .. In the present invention, the (A) blocked isocyanate is preferably a blocked isocyanate compound composed of an isocyanate having two or more isocyanate groups.

Even when this (A) blocked isocyanate compound is used together with (B) a compound containing at least two unsaturated groups at the terminal in one molecule, sufficient storage stability can be obtained as a sizing agent composition. Further, by applying the sizing agent composition to the carbon fiber and then heating it to a specific temperature or higher, the isocyanate group of the (A) blocked isocyanate compound reacts with the functional group on the fiber surface at the intended timing to form a covalent bond. A (bridged structure) can be generated and the surface of the carbon fiber can be coated with a reaction product having an unsaturated group. As a result, the adhesiveness between the carbon fiber and the matrix resin, particularly the adhesiveness with the radically reactive matrix resin such as unsaturated polyester and vinyl ester resin, is improved, and a fiber-reinforced composite material having excellent mechanical strength can be obtained. Can be done.

In the present invention, the (A) blocked isocyanate compound is preferably a compound having an aliphatic skeleton. Examples of the isocyanate compound as a precursor of the (A) blocked isocyanate compound include polyisocyanate compounds such as alkylene diisocyanate, dimethyldiphenyldiisocyanate, tolylene diisocyanate, metaphenylenedi isocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate and triphenylmethane triisocyanate. , These polyisocyanate compounds and compounds having two or more active hydrogen atoms, such as trimethylolpropane, pentaerythritol, etc., are reacted at a molar ratio in which the ratio of isocyanate group (-NCO) to hydroxyl group (-OH) exceeds 1. Examples thereof include a polyol adduct polyisocyanate compound containing a terminal isocyanate group. Among them, a compound having an aliphatic skeleton such as alkylene diisocyanate has a high degree of freedom of the molecular chain after the cross-linking reaction, imparts an appropriate binding force between the single fibers of the carbon fibers, and has the handleability of the carbon fibers. It is preferable because it is easy to achieve both adhesion with the matrix resin.

In the present invention, the dissociation temperature of the blocking agent that protects the isocyanate group of the (A) blocked isocyanate compound is preferably 50 to 250 ° C, more preferably 100 to 200 ° C, and particularly preferably 120 to 180 ° C. Examples of the blocking agent that deviates at such a temperature include oximes such as methylethylketooxime, acetone oxime, and cyclohexanone oxime, lactams such as acetylacetone and ε-caprolactam, phenols, and mercaptan. Of these, oximes such as methylethylketone oxime, acetone oxime, and cyclohexane oxime are particularly preferable as the blocking agent because they can be removed under relatively simple conditions.

[(B) A compound containing at least two unsaturated groups at the end of one molecule]
In the present invention, (B) as a compound containing at least two unsaturated groups at the end in one molecule, a compound having a calorific value of 100 μJ / mg or more in DTA measurement is used. By using a compound having a calorific value of 100 μJ / mg or more, self-polymerization proceeds sufficiently, and the adhesion between the carbon fiber bundle and the matrix resin, particularly the radically reactive matrix resin such as unsaturated polyester or vinyl ester resin. It is possible to obtain a carbon fiber reinforced composite material with improved adhesiveness to and with excellent mechanical strength, and by protecting the carbon fiber with this product, it is possible to obtain a carbon fiber bundle having excellent scratch resistance. can.

The calorific value of this compound in the DTA measurement is 100 μJ / mg or more, preferably 300 μJ / mg or more. If the calorific value is less than 100 μJ / mg, strong adhesion between the carbon fiber and the matrix resin cannot be obtained.

The compound (B) containing at least two unsaturated groups at the end in one molecule preferably has an unsaturated group content of three or more. When the number of unsaturated groups at the end of one molecule is 3 or more, the calorific value in the DTA measurement increases, self-polymerization proceeds sufficiently, and the adhesion between the carbon fiber and the matrix resin is particularly poor. Adhesion to radically reactive matrix resins such as saturated polyester and vinyl ester resin is improved, and carbon fiber reinforced composite materials with excellent mechanical strength can be obtained, and this product can protect carbon fibers. It is possible to obtain a carbon fiber bundle having excellent scratch resistance.

(B) The exothermic start temperature in the DTA measurement of the compound containing at least two unsaturated groups at the end in one molecule is preferably 150 ° C. or higher and 200 ° C. or lower. By using a compound having a heat generation start temperature in this range, self-polymerization can be performed by heat treatment after sizing, and the surface of the carbon fiber can be coated with a reaction product having an unsaturated group. As a result, the adhesiveness between the carbon fiber and the matrix resin, particularly the adhesiveness with the radically reactive matrix resin such as unsaturated polyester and vinyl ester resin is improved, and a carbon fiber reinforced composite material having excellent mechanical strength can be obtained. It is possible to protect the carbon fiber by this product, and it is possible to obtain the carbon fiber having excellent scratch resistance.

(B) The compound containing at least two unsaturated groups at the end in one molecule preferably has an unsaturated group equivalent (compound molecular weight / number of unsaturated groups) of 500 or less. By using a compound that satisfies this condition, a strong film can be formed on the surface of the carbon fiber, and a carbon fiber bundle having excellent scratch resistance can be obtained.

[Sizing agent composition]
The sizing agent composition of the present invention is a sizing agent composition containing the above-mentioned (A) blocked isocyanate compound and (B) a compound containing at least two unsaturated groups at the terminal in one molecule.

In the present invention, the mass ratio A / B of (A) the blocked isocyanate compound and (B) the compound containing at least two unsaturated groups at the terminal in one molecule is preferably 95/5 to 5/95. .. By satisfying this mass ratio, the adhesiveness between the carbon fiber and the matrix resin is particularly improved, and a fiber-reinforced composite material having excellent mechanical strength can be obtained.
Auxiliary components such as a dispersant and a surfactant may be added to the sizing agent composition of the present invention in order to improve the handleability of the carbon fiber bundle, the scratch resistance, the fluff resistance, and the impregnation property.

〔Carbon fiber〕
As the carbon fiber bundle used in the present invention, any carbon fiber bundle of carbon fiber such as pitch type, rayon type, acrylonitrile (PAN) type, single-walled carbon nanotube, multi-walled carbon nanotube, and carbon nanofiber can be used.
A carbon fiber bundle of acrylonitrile (PAN) -based carbon fiber is preferable in view of operability, process passability, and mechanical strength. Properties such as the fineness and strength of the carbon fibers of the carbon fiber bundle are arbitrary.

The carbon fiber bundle is a bundle of carbon fiber filaments, and the number of carbon fiber filaments constituting the carbon fiber bundle is, for example, 10 or more, preferably 100 or more, and particularly preferably 1,000 to 100,000. be. From the viewpoint of productivity, the number is preferably 3,000 to 80,000, particularly preferably 6,000 to 50,000. In the present invention, the carbon fiber bundle has a remarkable effect on the process passability during processing.

When the number of carbon fiber filaments constituting the carbon fiber bundle is less than 10, the flexibility of the carbon fiber bundle tends to increase and the handleability tends to be improved, but the productivity of the carbon fiber bundle tends to decrease, which is preferable. do not have. On the other hand, if the number exceeds 100,000, it may be difficult to produce carbon fiber bundles, and it tends to be difficult to sufficiently treat with a surface treatment agent, which is not preferable.

The shape of the carbon fiber bundle is preferably a flat fiber bundle. If the fiber bundle is flat, the sizing agent applied to the inside of the fiber bundle and the matrix resin used as a subsequent composite material are likely to diffuse. The flatness of the carbon fiber bundle (width / thickness of the carbon fiber bundle) is preferably 10 times or more, and particularly preferably 50 to 400 times.

The width of the carbon fiber bundle is preferably 5 mm or more, particularly preferably 10 to 100 mm, from the viewpoint of the impregnation property of the resin when composited with a resin such as prepreg.
When used as a discontinuous fiber, the length of the carbon fiber bundle is preferably 1 to 100 mm, more preferably 5 to 50 mm from the viewpoint of mechanical strength when used as a composite material.

The average diameter of the carbon fiber filaments (single yarns) constituting the carbon fiber bundle is preferably 0.001 to 100 μm, more preferably 3 to 20 μm, still more preferably 4 to 15 μm, and particularly preferably 5 to 10 μm. If the fiber diameter is smaller than this, the fiber component becomes bulky and it tends to be difficult to increase the volume fraction of the carbon fiber bundle, which is not preferable. On the other hand, if the fiber diameter is larger than this, it tends to be difficult to obtain high strength, which is not preferable. When the fiber diameter of the carbon fiber filament is in the above range, a composite material having excellent mechanical strength can be obtained.

[Adhesion of sizing agent]
As a method for adhering the sizing agent composition of the present invention to the carbon fiber bundle, it is preferable to use a method of preparing a sizing agent composition-containing liquid and adhering the sizing agent composition-containing liquid to the carbon fiber bundle (sizing treatment). .. Water is preferably used as the solvent used in the sizing agent composition-containing liquid. That is, it is preferable to use an aqueous dispersion of the sizing agent composition as the sizing agent composition-containing liquid.

Surfactants may be used to prepare the aqueous dispersion of the sizing agent composition. As this surfactant, for example, an anionic, cationic or nonionic surfactant can be used. Of these, nonionic surfactants are preferable from the viewpoint of emulsification performance and stability of the dispersion.

As nonionic surfactants, polyethylene glycol type (higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, etc.), polyhydric alcohol type (glycerin fatty acid ester, sorbitol, etc.) Surfactants such as fatty acid esters, fatty acid alkanolamides, etc.) can be exemplified.

The surfactant is used in an amount that can emulsify the sizing agent composition, and specifically, it is used in an amount of, for example, 0.1 to 30% by weight per 100% by weight of the sizing agent composition.
Examples of the emulsification method include a method using a batch equipped with a stirring blade, a method using a ball mill, a method using a shaker, and a method using a high shear emulsifier such as a gaulin homogenizer.

As an example of the method for sizing the carbon fiber bundle, a method of contacting the carbon fiber bundle with the sizing agent composition-containing liquid can be used. Specifically, a touch roll type carbon fiber in which a part of the roll is immersed in the sizing agent composition-containing liquid and surface-transferred, and then the carbon fiber bundle is brought into contact with the roll to adhere the sizing agent composition-containing liquid. An example can be exemplified of a dipping method in which the bundle is directly immersed in the sizing agent composition-containing liquid and then passed through a nip roll as needed to control the adhesion amount of the sizing agent composition-containing liquid.

As a method for removing the solvent of the sizing agent-containing liquid from the carbon fiber bundle, heat treatment, air drying, and centrifugation can be exemplified, and these may be used in combination. Heat treatment is preferable from the viewpoint of cost, and for example, hot air, a hot plate, a roller, and an infrared heater can be used as the heating means for the heat treatment.

[Adhesion to carbon fiber bundle]
The carbon fiber bundle to which the sizing agent composition of the present invention is attached has an MPF value defined as follows, preferably 60 or less, more preferably 30 or less.
MPF value (μg / ft) = captured fluff amount (μg) / evaluation fiber bundle length (ft)

In this measurement, a carbon fiber bundle to which the sizing agent composition was attached was run between five pin guides at a speed of 50 feet / minute for 2 minutes while applying a tension of 200 g, and then a weight of 125 g was placed on the carbon fiber bundle. The weight of the carbon fiber staying on the urethane sheet was measured by passing through the urethane sheet and used as the "captured fluff amount".

Hereinafter, a method for adhering the sizing agent composition of the present invention to the carbon fiber bundle will be described by taking as an example a method of adhering the sizing agent composition of the present invention to the carbon fiber bundle of the PAN-based carbon fiber.

<Precursor fiber>
The precursor fiber used in the method for producing carbon fiber is a spinning material containing 90% by mass or more of acrylonitrile, preferably 95% by mass or more, and 10% by mass or less of other monomers alone or copolymerized. Acrylic precursor fibers produced by spinning the solution are preferred. Examples of other monomers include itaconic acid and (meth) acrylic acid ester. Precursor fibers are obtained by washing, drying, drawing and oiling the raw material fibers after spinning with water. At this time, steam stretching is performed so that the total stretching ratio is 5 to 15 times. The number of filaments of the precursor fiber is preferably 1000 filaments or more, more preferably 6000 filaments or more in terms of production efficiency.

<Flame resistant treatment>
The obtained precursor fiber is preheat-treated at 200 to 260 ° C. and a draw ratio of 0.90 to 1.00 before flame resistance, and then subjected to flame resistance treatment at 200 to 260 ° C. in heated air for 10 to 100 minutes. The treatment at this time is generally performed in the range of a draw ratio of 0.85 to 1.15, but in order to obtain carbon fibers having high strength and high elastic modulus, 0.95 or more is more preferable. In this flame resistance treatment, the precursor fiber is made into an oxidized fiber having a fiber density of 1.34 to 1.38 g / cm ³ , and the tension (stretch distribution) at the time of flame resistance is not particularly limited. ..

<First carbonization treatment>
The flame-resistant fiber can be carbonized by adopting a conventionally known method. For example, the temperature is gradually raised in the first carbonization furnace at 300 to 800 ° C. under a nitrogen atmosphere, and the tension of the flame-resistant fiber is controlled to perform the first-stage carbonization under tension.

<Second carbonization treatment>
In order to further promote carbonization and graphitization (high crystallization of carbon), the temperature is gradually raised in the second carbonization furnace at 800 to 1600 ° C in an atmosphere of an inert gas such as nitrogen, and the first carbonization is carried out. The tension of the fiber is controlled for firing.

In each carbonization furnace, it is not preferable to suddenly change the temperature from the vicinity of the inlet of the furnace, for example, to suddenly introduce the fiber to the maximum temperature because many surface defects and internal defects are generated. Further, if the residence time is longer than necessary in the high temperature portion in the furnace, graphitization proceeds too much and brittle carbon fibers are obtained, which is not preferable. In the first carbonization treatment to the second carbonization step, the tension may be controlled and, if necessary, treatment may be performed in a plurality of furnaces so as to have predetermined physical properties.
If a higher elastic modulus is required, graphitization treatment may be further performed at a high temperature of 2000 to 3000 ° C.

<Surface oxidation treatment>
The carbon fiber strands are preferably surface-oxidized in an electrolytic solution. By performing the surface treatment, a functional group can be introduced on the surface of the carbon fiber, and the adhesiveness with the sizing agent and the matrix resin can be enhanced.

The amount of electricity applied to the carbon fibers in the surface treatment may be adjusted in a timely manner so as to have the desired amount of surface functional groups, but it is preferably in the range of 50 to 500 coulombs per 1 g of carbon fibers. When the amount of electricity applied to 1 g of carbon fiber is adjusted within this range, it is easy to obtain carbon fiber having excellent mechanical properties as a fiber and having improved adhesiveness to a resin. On the other hand, when the amount of electricity applied to 1 g of carbon fiber is less than 50 coulombs, the adhesiveness with the resin tends to decrease, and when it exceeds 500 coulombs, the fiber strength tends to decrease due to excessive treatment.

As the electrolytic solution, it is preferable to use an aqueous solution of an inorganic acid or an inorganic base and an inorganic salt. When a strong acid such as sulfuric acid or nitric acid is used as the electrolyte, the efficiency of surface treatment is good and preferable. Further, it is preferable to use an inorganic salt such as ammonium sulfate or sodium hydrogencarbonate as the electrolyte because the risk of the electrolytic solution is lower than that in the case of using an inorganic acid or an inorganic base.

The electrolyte concentration of the electrolytic solution is preferably 0.1 or more, and more preferably 0.1 to 1. If the electrolyte concentration is less than 0.1, it tends to be unsuitable for electrolysis due to its low electrical conductivity, while if the electrolyte concentration is too high, the electrolyte precipitates and the concentration becomes less stable. Tend.

The higher the temperature of the electrolytic solution, the better the electrical conductivity, so that the treatment can be accelerated. On the other hand, when the temperature of the electrolytic solution exceeds 40 ° C., it is difficult to provide uniform conditions without time variation due to fluctuations in concentration due to evaporation of water and the like, so the temperature is preferably between 15 and 40 ° C.

<Sizing process>
By passing the carbon fiber bundle subjected to the above surface treatment through the sizing agent composition-containing liquid of the present invention, the sizing agent composition is imparted to the carbon fiber bundle. The concentration of the sizing agent composition in the sizing agent composition-containing liquid is preferably 10 to 25% by weight. The amount of the sizing agent composition attached to the carbon fiber bundle is preferably 0.1 to 10% by weight, more preferably 0.2 to 5% by weight, and particularly preferably 0.2 to 5% by weight, based on 100% by weight of the carbon fiber bundle. It is 0.5 to 2% by weight.

The treatment for applying the sizing agent composition to the carbon fiber bundle is preferably performed by an emulsion method in which the carbon fiber bundle is immersed in an aqueous dispersion (aqueous emulsion) of the sizing composition obtained by using an emulsifier or the like. Auxiliary components such as a dispersant and a surfactant may be added to the sizing agent composition in order to improve the handleability, scratch resistance, fluff resistance and impregnation property of the carbon fiber bundle.

<Drying process>
The carbon fiber bundle after the sizing treatment is subjected to a drying treatment in order to evaporate the water or the like used as the dispersion medium in the sizing treatment, and a carbon fiber bundle to which the sizing agent composition is applied can be obtained. It is preferable to use an air dryer for drying. In the case of an aqueous dispersion (aqueous emulsion), the drying temperature is, for example, 100 to 200 ° C. This drying treatment (removal of the dispersion medium) may also serve as a heat treatment after the removal of the dispersion medium. After the drying treatment, a heat treatment may be performed separately from the drying treatment.

When the heat treatment is performed after the drying treatment, the temperature of the heat treatment is preferably (B) equal to or higher than the heat generation start temperature in the DTA measurement of the compound containing at least two unsaturated groups at the end in one molecule. By performing this heat treatment, the isocyanate group of the (A) blocked isocyanate compound can be reacted with the functional group on the surface of the carbon fiber after the surface treatment to form a crosslinked structure, and the surface of the carbon fiber of the carbon fiber bundle can be formed. , A reaction product having an unsaturated group can be coated, and (B) a compound containing at least two unsaturated groups at the end in one molecule self-polymerizes to form a carbon fiber in a carbon fiber bundle. The surface can be coated with a reaction product having an unsaturated group.

According to the present invention, there is provided a method for producing a sizing agent composition-attached carbon fiber bundle, which comprises a step of applying the sizing agent composition of the present invention to a carbon fiber bundle to form a sizing agent composition-attached carbon fiber bundle. ..

According to the present invention, further, a step of applying the sizing agent composition of the present invention to a carbon fiber bundle to form a sizing agent composition-adhered carbon fiber bundle, and (B) within one molecule contained in the sizing agent composition. A step of heat-treating the sizing agent composition-attached carbon fiber bundle at a temperature equal to or higher than the exothermic start temperature in the DTA measurement of a compound containing at least two unsaturated groups at the terminal, and a step of heat-treating the sizing agent composition-attached carbon fiber bundle in this order. Manufacturing method is provided.

[Carbon fiber composite material]
A carbon fiber composite material can be obtained by molding the carbon fiber bundle to which the sizing agent composition is applied in combination with a matrix resin in this way. As a molding method
For example, autoclave molding, press molding, resin transfer molding, and filament winding molding can be used.
According to the present invention, there is provided a carbon fiber composite material composed of the above-mentioned sizing agent composition-adhered carbon fiber and a matrix resin.

The carbon fiber bundle used for molding the carbon fiber composite material is preferably processed into a sheet shape. Examples of the sheet-shaped carbon fiber bundles include those in which the individual carbon fibers of the carbon fiber bundles are arranged in a sheet shape in one direction, those in which the carbon fiber bundles are molded into a cloth such as a woven or knitted fabric or a non-woven fabric, and a multi-axis fabric. can do. When used as a non-woven fabric, it may be a non-woven fabric made of continuous fibers or a non-woven fabric made of discontinuous fibers.
When the carbon fiber bundle is used as a sheet-like material, the basis weight is preferably 25 to 10000 g / m ² .

[Matrix resin]
As the matrix resin, a thermosetting resin or a thermoplastic resin can be used. Specific examples of the thermosetting resin include epoxy resin, unsaturated polyester resin, phenol resin, vinyl ester resin, cyanate ester resin, urethane acrylate resin, phenoxy resin, alkyd resin, urethane resin, maleimide resin and cyanate ester resin. Examples thereof include a prepolymer resin, a bismaleimide resin, a polyimide resin having an acetylene terminal, a polyisoimide resin, and a polyimide resin having a nadic acid terminal. These can also be used as one kind or a mixture of two or more kinds. Of these, epoxy resins and vinyl ester resins having excellent heat resistance, elastic modulus, and chemical resistance are particularly preferable. In addition to the curing agent and the curing accelerator, these thermosetting resins may contain commonly used colorants, various additives, and the like.

Examples of the thermoplastic resin include polypropylene, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, aromatic polyamide, aromatic polyester, aromatic polycarbonate, polyetherimide, polyarylene oxide, thermoplastic polyimide, and polyamide. , Polyamideimide, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyacrylonitrile, polyaramid, polybenzimidazole can be exemplified.

The content of the matrix resin in the carbon fiber composite material is, for example, 10 to 90% by weight, preferably 20 to 60% by weight, and more preferably 25 to 45% by weight.
The carbon fiber reinforced composite material thus obtained has excellent adhesion between the carbon fiber bundle and the matrix resin, and has excellent mechanical strength.

Hereinafter, the present invention will be specifically described with reference to examples. The physical properties were measured by the following method.

(1) Adhesion amount of sizing agent The adhesion amount of the sizing agent is determined by collecting two treated 1.0 m sizing agent-adhered fiber bundles, raising the temperature to 550 ° C. at 10 ° C./min under a nitrogen atmosphere, and then raising the temperature to 550 ° C. It was fired at the same temperature for 10 minutes, and the amount of weight loss was calculated by the following formula as the amount of the sizing agent adhered.
Adhesion amount of sizing agent = (ab) / b × 100 [%]
a: Fiber weight before firing [g]
b: Fiber weight after firing treatment [g]

(2) MPF
The MPF value is defined by the following formula.
MPF value (μg / ft) = captured fluff amount (μg) / evaluation fiber bundle length (ft)
In this measurement, a carbon fiber bundle to which the sizing agent composition was attached was run between five pin guides at a speed of 50 feet / minute for 2 minutes while applying a tension of 200 g, and then a weight of 125 g was placed on the carbon fiber bundle. The amount of carbon fiber staying on the urethane sheet was measured by passing through the urethane sheet and used as the "captured fluff amount".

(3) Interfacial shear strength IFSS (microdroplet method)
Interface shear strength (IFSS) by microdroplet method using the following matrix resin prepared with 100 parts by weight of vinyl ester resin, 1 part by weight of peroxide curing agent, and 0.5 part of cobalt naphthenate as a catalyst. Was measured.

(4) DTA measurement (heat generation start temperature / heat generation amount)
Using Rigaku's thermogravimetric / differential thermal measuring device Thermo plus EVO2, the heat generation start temperature and heat generation amount were measured under the conditions of a temperature rise rate of 10 ° C./min and an air flow rate of 100 ml / min.

[Sizing agent composition]
The compounds used to prepare the sizing agent composition are shown below.

<(A) Blocked isocyanate compound>
NBP-873D: NBP-873D (product name) manufactured by Meisei Kagaku Kogyo Co., Ltd., hexamethylene diisocyanate trimmer (aliphatic blocked isocyanate) blocked with methyl ethyl ketooxime group, isocyanate group content 4, deviation temperature = 150 ° C.
NBP-411: NBP-211 (product name) manufactured by Meisei Kagaku Kogyo Co., Ltd., a polyol adduct polyisocyanate compound (aliphatic blocked isocyanate) having a hexamethylene diisocyanate trimmer and an ethylene glycol skeleton blocked with a methylethylketooxime group, an isocyanate group. Content 4, deviation temperature = 150 ° C

<(B) A compound having at least two unsaturated groups at the end in one molecule>
-ATM-35E: ATM-35E (product name) manufactured by Shin Nakamura Chemical Industry Co., Ltd., ethoxylated pentaerythritol tetraacrylate, content of acrylic group at the end in one molecule 4, heat generation start temperature 175.7 ° C, calorific value 381 μJ / Mg
-A-9300-1CL: A-9300-1CL (product name) manufactured by Shin Nakamura Chemical Industry Co., Ltd., ε-caprolactone-modified tris- (2-acryloxyethyl) isocyanurate The content of the terminal acrylic group in one molecule 3. Heat generation start temperature 194.6 ° C., calorific value 711 μJ / mg
BPE-500: BPE-500 (product name) manufactured by Shin Nakamura Chemical Industry Co., Ltd., ethoxylated bisphenol A dimethacrylate, content of methacrylic group at the end in one molecule 2, heat generation start temperature 171.3 ° C, calorific value 30 μJ / Mg
CN 989NS: CN 989NS (product name) manufactured by Sartmer, aliphatic urethane acrylate, content of acrylic group at the end in one molecule 3, heat generation start temperature 208.5 ° C, calorific value 194 μJ / mg

[Example 1]
(A) NBP-211 as a blocked isocyanate compound and ATM-35E as a compound (B) having at least two unsaturated groups at the end in one molecule are mixed at an active ingredient ratio (mass ratio) of 25/75 to form a sizing agent. It was made into a composition.

The polyacrylonitrile fiber was flame-resistant in air at 250 ° C. and then carbonized at a maximum temperature of 650 ° C. under a nitrogen gas atmosphere. Then, the carbon fibers produced by high-temperature carbonization at 1300 ° C. under a nitrogen atmosphere were surface-treated by electrolytic oxidation using a 10 wt% ammonium sulfate aqueous solution, and the unsized carbon fiber bundle (tensile strength: 4300 MPa, tensile elastic modulus:). 240 GPa, number of filaments: 24,000) was obtained. The obtained unsized carbon fiber bundle is continuously immersed in a sizing bath in which the above sizing agent composition is diluted with water, and the sizing agent composition is prepared so that the adhered amount of the sizing agent composition is 1% by weight. Granted. Then, water was removed by a hot air dryer having an atmospheric temperature of 200 ° C. and heat treatment was performed to obtain a carbon fiber bundle adhering to the sizing agent composition. The evaluation results of MPF and IFSS are shown in Table 1.

[Example 2]
(A) NBP-211 as a blocked isocyanate compound and (B) A-9300-1CL as a compound having at least two unsaturated groups at the terminal in one molecule are mixed at an active component ratio (mass ratio) of 25/75. A sizing treatment was carried out in the same manner as in Example 1 except that the sizing agent composition was obtained, and a carbon fiber bundle adhering to the sizing agent composition was obtained. The evaluation results of MPF and IFSS are shown in Table 1.

[Example 3]
(A) NBP-873D as a blocked isocyanate compound and (B) ATM-35E as a compound having at least two unsaturated groups at the ends in one molecule are mixed at an active ingredient ratio (mass ratio) of 25/75 to form a sizing agent. A sizing treatment was carried out in the same manner as in Example 1 except that the composition was prepared, to obtain a carbon fiber bundle adhering to the sizing agent composition. The evaluation results of MPF and IFSS are shown in Table 1.

[Example 4]
(A) NBP-873D as a blocked isocyanate compound and (B) A-9300-1CL as a compound having at least two unsaturated groups at the ends in one molecule are mixed at an active component ratio (mass ratio) of 25/75. A sizing treatment was carried out in the same manner as in Example 1 except that the sizing agent composition was obtained, and a carbon fiber bundle adhering to the sizing agent composition was obtained. The evaluation results of MPF and IFSS are shown in Table 1.

[Example 5]
(A) NBP-211 as a blocked isocyanate compound, (B) ATM-35E as a compound having at least two unsaturated groups at the ends in one molecule are mixed at an active ingredient ratio (mass ratio) of 50/50 to make a sizing agent. A sizing treatment was carried out in the same manner as in Example 1 except that the composition was prepared, to obtain a carbon fiber bundle adhering to the sizing agent composition. The evaluation results of MPF and IFSS are shown in Table 1.

[Example 6]
(A) NBP-873D as a blocked isocyanate compound and (B) A-9300-1CL as a compound having at least two unsaturated groups at the ends in one molecule are mixed at an active component ratio (mass ratio) of 50/50. A sizing treatment was carried out in the same manner as in Example 1 except that the sizing agent composition was obtained, and a carbon fiber bundle adhering to the sizing agent composition was obtained. The evaluation results of MPF and IFSS are shown in Table 1.

[Example 7]
(A) NBP-211 as a blocked isocyanate compound, and (B) CN 989NS as a compound having at least two unsaturated groups at the ends in one molecule are mixed at an active ingredient ratio (mass ratio) of 25/75 to form a sizing agent. A sizing treatment was carried out in the same manner as in Example 1 except that the sizing agent composition was obtained. The evaluation results of MPF and IFSS are shown in Table 1.

[Example 8]
(A) NBP-211 as a blocked isocyanate compound, (B) ATM-35E as a compound having at least two unsaturated groups at the ends in one molecule are mixed at an active component ratio (mass ratio) of 10/90 to obtain a sizing agent. A sizing treatment was carried out in the same manner as in Example 1 except that the composition was prepared, to obtain a carbon fiber bundle adhering to the sizing agent composition. The evaluation results of MPF and IFSS are shown in Table 1.

[Comparative Example 1]
(A) NBP-211 as a blocked isocyanate compound and (B) BPE-500 as a compound having at least two unsaturated groups at the ends in one molecule are mixed at an active ingredient ratio (mass ratio) of 25/75 to form a sizing agent. A sizing treatment was carried out in the same manner as in Example 1 except that the composition was prepared, to obtain a carbon fiber bundle adhering to the sizing agent composition. The evaluation results of MPF and IFSS are shown in Table 1.

The sizing agent composition of the present invention can be used for producing a carbon fiber bundle, and the carbon fiber bundle can be used as a component of a carbon fiber composite material, such as an aircraft member, a spacecraft member, an automobile member, a ship member, and a civil engineering and building material. And can be used for sports equipment and the like.

Claims (5)

A sizing agent composition comprising (A) a blocked isocyanate compound and (B) a compound containing at least two unsaturated groups at the ends within a molecule, wherein (B) at least two unsaturated groups at the ends within one molecule. A sizing agent composition, which comprises a calorific value of 100 μJ / mg or more in the DTA measurement of a compound containing a saturated group. (B) The sizing agent composition according to claim 1, wherein the heat generation start temperature in the DTA measurement of the compound containing at least two unsaturated groups at the end in one molecule is 150 ° C. or higher and 200 ° C. or lower. Claim 1 in which the mass ratio A / B of the (A) blocked isocyanate compound and the (B) compound containing at least two unsaturated groups at the terminal in one molecule is 95/5 to 5/95. Or the sizing agent composition according to 2. A method for producing a sizing agent composition-attached carbon fiber bundle, which comprises a step of applying the sizing agent composition according to any one of claims 1 to 3 to a carbon fiber bundle to form a sizing agent composition-attached carbon fiber bundle. A step of applying the sizing agent composition according to any one of claims 1 to 3 to a carbon fiber bundle to form a sizing agent composition-adhered carbon fiber bundle, and (B) within one molecule contained in the sizing agent composition. A step of heat-treating the sizing agent composition-attached carbon fiber bundle at a temperature equal to or higher than the exothermic start temperature in the DTA measurement of a compound containing at least two unsaturated groups at the terminal, and a step of heat-treating the sizing agent composition-attached carbon fiber bundle in this order. Manufacturing method.