JP6805415B2 - Adhesive improver for carbon materials and composite materials using it - Google Patents

Description

The present invention relates to a dispersion promoting agent for carbon materials, an adhesiveness improver, a surface-modified carbon material modified with an adhesiveness improver, and a carbon composite material using these.

A carbon material generally refers to a material composed of carbon atoms, and exhibits various forms and functions depending on the bonding mode and assembly mode of carbon atoms. Among them, graphite, fullerene, carbon nanotube, graphene, carbon fiber (carbon fiber), activated carbon , Diamond-like carbon, carbon black, etc. have been attracting attention for a long time, reinforcing materials (aircraft, automobiles, sporting goods, tires), catalyst carriers, electrode materials (dry batteries, fuel cells), molecular sieve membranes, water purification adsorbents, deodorants. , Cosmetics, shampoos, face masks, surface coats, electromagnetic wave shielding materials, heat dissipation materials, pharmaceuticals (adsorbents).

Carbon materials consist of a 6-membered ring structure of carbon atoms and do not have polarity, so they have poor wettability and dispersibility with general-purpose materials, and have insufficient adhesion to matrix resins, so they have been used in various physical and chemical fields. Surface hydrophilization treatment has been performed by a specific method. For example, in carbon fiber, the adhesiveness with an epoxy resin is improved by introducing an amino group on the surface (Non-Patent Document 1), and the epoxy resin and 1,3-phenylene bis-2- as a sizing agent on the surface. It was reported that fluffing could be prevented by adhering oxazoline (Patent Document 1). In graphite particles, ionic carbon-fluorine bonds were formed on the surface by direct fluorine treatment, and the dispersion stability in water was significantly improved (Non-Patent Document 2). In addition, using diamond powder and fine particles, oxygen-containing functional groups such as hydroxyl groups are introduced on the surface by strong acid treatment at high temperature or irradiation with ultraviolet rays in the presence of hydrogen peroxide, and the oxygen-containing functional groups such as hydroxyl groups are introduced into general-purpose solvents such as water and alcohol. A method for producing diamond that can be stably dispersed has been disclosed (Patent Documents 2 and 3).

Further, carbon nanotubes (CNTs) have a fibrous structure having a diameter of several to several tens of nm and a length of several to several hundred μm, and have been actively studied in recent years as a typical nano-sized carbon material. Since the aspect of CNT is very large, it shows excellent electrical, thermal, and mechanical properties, but it is very easy to get entangled, and it is not only for general-purpose resin-based and metal-based materials, but also for similar carbon-based matrices. However, the wettability, interfacial adhesion, adhesiveness, etc. are poor, and a high-performance composite material utilizing the characteristics of CNT has not yet been obtained.

Several techniques have been disclosed for surface modification of CNTs in order to develop highly functional composite materials. Non-Patent Document 3 describes a method in which silicon is sublimated in a vacuum high temperature (1400 ° C.) state, vapor-deposited on the CNT surface, a SiC layer is formed on the CNT surface by a high temperature reaction, and an alloy serving as a base material is adhered by improving wettability. Proposed. Further, in Non-Patent Document 4, after heat-treating CNT (2000 ° C.), surface treatment is performed using hydrogen peroxide solution and ultraviolet rays, and then a resin composite material using polycarbonate as a base material is prepared to prepare a resin. We proposed a method to improve the mechanical strength of the. However, since these CNT surface modification methods are carried out under vacuum or ultra-high temperature conditions, special equipment is required, and it cannot be said that they are industrial manufacturing methods in terms of equipment and cost. ..

On the other hand, a technique has also been proposed in which the resin composited with CNT is made into a special specification without treating CNT in particular. In Patent Document 4, in the first step, the polymer (A) having an oxazoline group in the side chain, the thermoplastic resin (B) and the modified thermoplastic resin (C) are mixed by a twin-screw extruder at 180 ° C. for 10 minutes. The mixture was melt-kneaded to obtain a filler dispersion resin composition (D). In the second step, the filler CNT (E) and the filler (D) obtained in the first step are melt-kneaded again at 180 ° C. for 10 minutes with a twin-screw extruder to obtain a thermoplastic resin exhibiting conductivity. It was disclosed that the complex was acquired. Although this method is effective for a specific thermoplastic resin, it is a thermoplastic resin or thermosetting resin that is incompatible with a polymer having a high melting point or a thermally decomposable thermoplastic resin or an oxazoline group in a side chain, or a modified thermoplastic resin. , Metal-based materials, carbon materials, etc. cannot be melt-kneaded, so that a resin composition for filler dispersion cannot be obtained, and compounding with CNT is not as expected.

Carbon, 2000, No. 195, 336-340 Journal of the Chemical Society of Japan, 1993, No. 6, 746-751 Nagano Technical Center Research Bulletin, 2006, No. 1, M10-M15 2013 Spring Meeting of the Japan Society for Precision Engineering Academic Lecture Proceedings, 659-660

Japanese Unexamined Patent Publication No. 5-132874 Japanese Unexamined Patent Publication No. 9-025110 Japanese Unexamined Patent Publication No. 2012-046378 Japanese Unexamined Patent Publication No. 2014-149164

The present invention does not require special dispersion or surface treatment technology or equipment, does not impair the original characteristics of the carbon material, and promotes dispersion that can impart hydrophilicity and adhesiveness to the surface of various carbon materials by a simple method. It is an object of the present invention to provide an agent and an adhesiveness improver, and to provide a carbon material (surface modified carbon material) whose surface is modified by using the adhesiveness improver. The adhesiveness improver and the surface-modified carbon material can be produced in high yield by industrial means, and by reacting with various solid materials, a suitable carbon composite material having specific performance can be obtained. The task is to provide.

As a result of diligent studies to solve these problems, the present inventors have found that a copolymer containing a 2-oxazoline-based monomer (a) and a nitrogen-containing heterocyclic monomer (b) as constituent units is carbon. It has been found that it exhibits peculiar performance in promoting dispersion of materials in other materials and improving surface adhesiveness of carbon materials. Further, by reacting with various carbon materials using the adhesiveness improving agent composed of the copolymer, it was possible to obtain a surface-modified carbon material having imparted adhesiveness. Furthermore, carbon that has excellent mechanical properties, good heat resistance, abrasion resistance, heat dissipation and conductivity by reacting with general-purpose carbon materials and thermoplastic resins using an adhesiveness improver and a surface-modified carbon material. A composite material could be obtained, the above problems were solved, and the present invention was reached.

That is, the present invention
(1) A copolymer (A) containing 1 to 90 mol% of a 2-oxazoline-based monomer (a) and 10 to 99 mol% of a nitrogen-containing heterocyclic monomer (b) as constituent units.
(2) The copolymer (A) according to (1) above, wherein the nitrogen-containing heterocyclic monomer (b) is vinylpyrrolidone.
(3) A dispersion accelerator for carbon materials using the copolymer (A) according to the above (1) or (2).
(4) The carbon material is a carbon nanotube The dispersion accelerator for a carbon material according to the above (3) (5) Adhesiveness for a carbon material using the copolymer (A) according to the above (1) or (2). Improver (6) A surface-modified carbon material, which is surface-modified with the adhesiveness improver according to (5) above.
(7) The surface-modified carbon material according to (6) above, wherein the surface contains 0.1 to 100 mg / m ^{2 of} an adhesiveness improver.
(8) A method for producing a surface-modified carbon material, which comprises heating the adhesive improver according to the above (5) in a liquid medium while contacting the surface of the carbon material.
(9) A method for producing a surface-modified carbon material, which comprises bringing the adhesiveness improver according to (5) into contact with the surface of the carbon material in a liquid medium and then heating the material.
(10) A carbon composite material composed of the surface-modified carbon material and the solid material according to the above (6) or (7), and the solid material includes a carboxyl group, a phenolic hydroxyl group, an acid anhydride functional group, and an epoxy. It has one or more functional groups that can be selected from the group consisting of a group, a thiol group, an amine group and an amide group, and a chemical bond formed by reacting with the oxazoline group of these functional groups is formed between the surface-modified carbon material and the solid material. Carbon composite material, characterized by being present,
(11) The carbon composite material according to (10) above, wherein the solid material is a carbon material.
(12) The carbon composite material according to (10) above, wherein the solid material is a thermoplastic resin. (13) The solid material is a carbon material and a thermoplastic resin. It provides the described carbon composite material.

The copolymer (A) of the present invention contains 1 to 90 mol% of the 2-oxazoline-based monomer (a) and 10 to 99 mol% of the nitrogen-containing heterocyclic monomer (b) as constituent units. If the contents of (a) and (b) are within this range, the obtained copolymer (A) is a homopolymer of a 2-oxazoline-based monomer, a homopolymer of a nitrogen-containing heterocyclic monomer, and these. Compared with a mixture of homopolymers (blended polymer), a specific effect was confirmed as both a dispersion accelerator for carbon materials and an adhesiveness improver. The composition and structure of the polymer are unclear as to the causal relationship with the specific effect, but the inventor said that it is more effective if (a) and (b) of the present invention are partially arranged in a block shape. Are guessing.

The copolymer (A) of the present invention has a nitrogen-containing heterocycle having a high affinity with a carbon material and an oxazoline group having a high reactivity with a carboxylic acid or a phenolic hydroxyl group on the surface of the carbon material, and has a large aspect such as CNT. Even in a carbon material, it can be easily dispersed in water, an organic solvent, or a plastic resin, reaggregation is suppressed, and a stable dispersed state can be maintained.

By using the copolymer (A) of the present invention as an adhesiveness improver and reacting it with various carbon materials under mild conditions, the surface of the carbon material is uniformly covered with the adhesiveness improver and removed. A surface-modified carbon material that does not separate can be easily produced by an industrial method. Further, since the obtained surface-modified carbon material has an unreacted oxazoline group on the surface, various solid materials such as the same or different carbon materials, a carboxyl group capable of reacting with an oxazoline group, a phenolic hydroxyl group, and an acid anhydride are used. Unique performance that combines the characteristics of carbon material and resin material by reacting with a solid thermoplastic resin having one or more functional groups that can be selected from the group consisting of a physical functional group, an epoxy group, a thiol group, an amine group and an amide. A carbon composite material having the above can be easily obtained.

Hereinafter, the present invention will be described in detail.
The copolymer (A) of the present invention is characterized by containing a 2-oxazoline-based monomer (a) and a nitrogen-containing heterocyclic monomer (b) as constituent units. Since the nitrogen-containing heterocycle has a high affinity for the carbon material, it has an effect of promoting the dispersion of the carbon material in other kinds of organic or inorganic liquid or solid materials, and the oxazoline group is on the surface of the carbon material. Since it has high reactivity with the carboxylic acid or phenolic hydroxyl group of the above, it is possible to prevent the reaggregation of the carbon material once dispersed, so that a stable dispersion effect can be provided. The copolymer (A) contains (a) and (b) in a specific compounding ratio, that is, (a) contains 1 to 90 mol% and (b) contains 10 to 99 mol%. Is preferable. If the content of (a) is less than 1 mol%, reaggregation after dispersion may not be sufficiently suppressed in a carbon material having a very large aspect such as CNT, and when it is used as an adhesive improver, it may not be sufficiently suppressed. Since it is difficult to cover the surface of the carbon material completely and uniformly, there is a possibility that a sufficient adhesiveness improving effect cannot be obtained. On the other hand, when the content of (a) exceeds 90 mol%, the content of (b) is relatively reduced, and there is a possibility that a portion that cannot be completely dispersed remains. If the content of (b) is 10 mol% or more, a good dispersed state is formed even in various carbon materials, and if the content of (b) exceeds 99 mol%, the content of the reactive oxazoline group is formed. However, there is a problem that the dispersion stability and the effect of improving the adhesiveness cannot be satisfied. The copolymer of the present invention, and the dispersion accelerator and the adhesiveness improver obtained from the copolymer have the effect of suppressing reaggregation and the effect of improving the adhesiveness due to the reactivity of the oxazoline group of (a) and the carbon of the nitrogen-containing heterocycle of (b). It is considered that excellent dispersibility, dispersion stability and adhesiveness improving effect can be maximized because the high affinity for the material and the steric hindrance due to the cyclic structure are well balanced. Further, the copolymer (A) is not only uniformly arranged on the surface of the carbon material, but also strongly bonded to the carbon material via a chemical bond formed by a chemical reaction, and reacts with hydrophilicity on the surface of the carbon material. Since the properties are simultaneously imparted, it is the most specific effect that can be provided as the adhesiveness improver of the present invention that it easily adheres to the surface of the carbon material and does not detach semipermanently.

The 2-oxazoline-based monomer (a) is 2-vinyl-2-oxazoline, 4-methyl-2-vinyl-2-oxazoline, 5-methyl-2-vinyl-2-oxazoline, 4-ethyl-2-vinyl-. 2-Oxazoline, 5-ethyl-2-vinyl-2-oxazoline, 4,4-dimethyl-2-vinyl-2-oxazoline, 4,4-diethyl-2-vinyl-2-oxazoline, 4,5-dimethyl- 2-Vinyl-2-oxazoline, 4,5-diethyl-2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 4-methyl-2-isopropenyl-2-oxazoline, 5-methyl-2- Isopropenyl-2-oxazoline, 4-ethyl-2-isopropenyl-2-oxazoline, 5-ethyl-2-isopropenyl-2-oxazoline, 4,4-dimethyl-2-isopropenyl-2-oxazoline, 4, One or more selectable from the group consisting of 4-diethyl-2-isopropenyl-2-oxazoline, 4,5-dimethyl-2-isopropenyl-2-oxazoline, and 4,5-diethyl-2-isopropenyl-2-oxazoline It is a monomer of. Among these 2-oxazoline-based monomers, 2-vinyl-2-oxazoline and 2-isopropenyl-, which have high reactivity with functional groups such as carboxyl group, phenolic hydroxyl group, acid anhydride group and thiol group. 2-Oxazoline, 5-methyl-2-vinyl-2-oxazoline, 4,4-dimethyl-2-vinyl-2-oxazoline are preferable, and 2-vinyl-2-oxazoline and 2-isopropenyl-2-oxazoline are preferable. Most preferred.

The nitrogen-containing heterocyclic monomer (b) is N-vinylpyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole. , N-vinylimidazole, N-vinyloxazole, N- (meth) acryloylpyrrolidone, N- (meth) acryloylpiperidin, N- (meth) acryloylpyrrolidin, N- (meth) acryloylmorpholine, N-vinylmorpholin, N- Vinyl piperidone, N-vinyl-3-morpholinone, N-vinylcaprolactam, N-vinyl-1,3-oxadin-2-one, N-vinyl-3,5-morpholindione, N-vinylpyrazole, N-vinylisoxazole , N-vinylthyazole, N-vinylisothyazole, N-vinylpyridazine, or one or more kinds of monomers that can be selected from the group. Among these nitrogen-containing heterocyclic monomers, N-vinylpyrrolidone, N-vinylimidazole, N-vinylcaprolactam, and N-acryloylmorpholine are used from the viewpoint of affinity with carbon materials and copolymerizability of vinyl groups. Is preferable.

The copolymerization method of the 2-oxazoline-based monomer (a) and the nitrogen-containing heterocyclic monomer (b) is not particularly limited, and can be carried out by a known radical polymerization method. Examples thereof include solution polymerization, suspension polymerization, emulsion polymerization, and massive polymerization in organic solvents such as alcohol and ethyl acetate and in water. When the solution polymerization method in an organic solvent is adopted, the polymerization solvent may be toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl alcohol, ethyl alcohol or the like alone or in combination.

Examples of the polymerization initiator used for the copolymerization include generally known polymerization initiators such as azo-based, organic peroxide-based, inorganic peroxide-based, and redox-based. The amount of the polymerization initiator used is usually about 0.001 to 10% by weight based on the total amount of the polymerizable monomer components. In addition, ordinary radical polymerization techniques such as adjustment of molecular weight with a chain transfer agent are applied.

Further, the 2-oxazoline-based monomer (a) and the nitrogen-containing heterocyclic monomer (b) can be used as a constituent unit for multidimensional copolymerization with other copolymerizable vinyl-based monomers. Other copolymerizable vinyl-based monomers include (meth) acrylates having alkyl groups of carbon chains 1-12, N-alkyl (meth) acrylamides having alkyl groups of carbon chains 1-12, the same or different. N, N-dialkyl (meth) acrylamide with two alkyl groups of carbon chains 1-12, (meth) acrylate or (meth) acrylamide with aromatic substituents, hydroxyalkyl (C1-12) (meth) acrylate or Examples thereof include (meth) acrylamide, (meth) acrylonitrile, and (meth) acrylic acid. These copolymerizable vinyl-based monomers may be used alone or in combination of two or more, and the total mole fraction of various other copolymerizable vinyl-based monomers to be blended is 30. % Or less is preferable.

The molecular weight of the copolymer (A) of the present invention is 1,000 to 100,000 on average by weight. Further, it is preferably 2,000 to 50,000, more preferably 4,000 to 30,000. If the weight average molecular weight is less than 1,000, initial dispersion failure of a poorly dispersed carbon material such as CNT may occur, and even as an adhesive improver, non-uniform adhesion to the surface of the carbon material is likely to occur, which is not preferable. .. On the other hand, when the weight average molecular weight exceeds 500,000, the viscosity of the copolymer solution dissolved in the liquid dispersant increases remarkably, and as a result, the dispersibility and surface adhesiveness of the carbon material tend to decrease. ..

The carbon material used in the present invention is a material (carbon material) mainly composed of carbon only, and can be roughly divided into carbon fiber and nanocarbon material. Examples of carbon fibers include polyacrylonitrile (PAN) type, pitch type, rayon type and plant-derived raw material type, and nanocarbon materials include fullerenes, carbon nanotubes (CNT), and vapor-grown carbon fibers (nano). Fibers), graphene, graphite, and other nanocarbons. Among them, PAN-based carbon fiber is more preferable as a fiber-based fiber because it has excellent strength and elastic modulus per unit weight and a large amount of production, and CNT can control the structure at the nanometer level and is inexpensively industrialized as a new functional material. It is preferable as a nano-carbon material because it can be manufactured at a suitable level. Further, these carbon materials may be used as they are on the market, or may be used after being treated by a treatment method such as oxidation to generate many carboxyl groups or phenolic hydroxyl groups on the surface.

The carbon materials used in the present invention may be used alone or in combination of two or more depending on their respective purposes. In addition, although these carbon materials can usually be used as commercially available products, they are subjected to physical dispersion treatment such as cleaning with a solvent, bead mill dispersion treatment for disentanglement between CNTs, and ultrasonic dispersion treatment. It is more preferable to use from.

As the dispersant for the carbon material used in the present invention, organic solvents and water that are liquid at room temperature (25 ° C.) are preferable. Solvents include alcohols such as methanol, ethanol, isopropyl alcohol (IPA) and butanol, ketones such as acetone, methyl ethyl ketone (MEK) and methyl isobutyl ketone, esters such as ethyl acetate, propyl acetate and butyl acetate, and ethylene glycol. Ethers such as monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-butyl ether, ethylene glycol monomethyl ether, tetrahydrofuran (THF), toluene, xylene, chloroform, N-methylpyrrolidone (NMP), N-methylformamide. (NMF), N, N-dimethylformamide (DMF), N-methylacetamide, dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), cyclohexane, polyhydric alcohol, silicone oil, cationic, anionic, amphoteric It can be widely used such as sex or nonionic surfactants. Further, a combination of any one or more of these solvents may be used, or a mixture of a water-soluble organic solvent and water in an arbitrary compounding ratio may be used.

In the above solvent dispersant, a hydrophilic solvent having a nitrogen atom or a sulfur atom in a molecule such as NMP, NMF, DMF, DMSO has a strong interaction with the copolymer (A) of the present invention, thereby. It is preferable because it has an effect of preventing the reaggregation of a carbon material such as CNT and a stable dispersion liquid is easily formed. Further, when water is used as a dispersant, since it does not have an organic solvent to be discarded, it has an environmentally friendly advantage, and the disadvantage of insufficient dispersibility is that the copolymer (A) of the present invention is added. It is particularly preferable as a dispersant for environmentally friendly carbon materials.

The blending amount of the copolymer (A) of the present invention as a dispersion accelerator for carbon materials and an adhesiveness improver varies greatly depending on the type, form, size, presence / absence and method of pretreatment of the carbon material and dispersant. However, it is preferably 0.01 to 20% by mass with respect to the dispersant and 0.1 to 100 mg / m ² with respect to the carbon material. Further, in carbon fibers (CF) and carbon nanotubes (CNTs) having a particularly difficult dispersion aspect, 0.01 to 10% by mass with respect to the dispersant and 0.1 to 80 mg / m with respect to the carbon material. and more preferably ^2.

If the blending amount of the copolymer (A) is less than 0.01% by mass with respect to the dispersant, there is a possibility that sufficient dispersion may occur depending on the type and concentration of the carbon material, and uniform dispersion may occur. Even if a liquid is obtained, when the carbon material is subsequently adhered to the solid material using the dispersion liquid, the effect as an adhesiveness improving agent cannot be sufficiently provided, and a uniform and high-strength carbon material adhesive layer can be obtained. It may not be. On the other hand, when the blending amount of the copolymer (A) exceeds 20% by mass with respect to the dispersant, the effect of promoting the dispersion of the carbon material is high, and there is no problem in forming a uniform dispersion liquid. In adhesion to a solid material, a portion where the carbon material is adhered at a high concentration is likely to occur, and the surface-modified carbon material or carbon formed by adhering the solid material and the coal layer material via the copolymer (A) is likely to occur. It is not preferable because the properties of the composite material may be non-uniform.

In the present invention, the obtained dispersion liquid of the carbon material can be used to bond the carbon material to the solid material. At that time, when the blending amount of the copolymer (A) as the adhesiveness improving agent is 0.1 to 100 mg / m ² with respect to the carbon material, the carbon material can be adhered to the solid material uniformly and with high strength. Can be preferred.

The dispersion accelerator for carbon materials and the adhesiveness improver for carbon materials of the present invention are both characterized by containing the copolymer (A). The copolymer (A) contained therein may have the same composition and structure, or may have a different composition and structure, and one kind or a mixture of two or more kinds can be used. Further, from the viewpoint of low cost and easy process control, it is preferable that the agent is a dispersion accelerator and at the same time an adhesiveness improver.

The method for producing a surface-modified carbon material of the present invention can be roughly divided into two depending on the types of dispersant and adhesion improver (hereinafter abbreviated as dispersant and the like) and the reaction method between the carbon material and the adhesion improver. One is a method of heating the adhesiveness improver composed of the copolymer (A) while contacting the surface of the carbon material in the liquid medium, and the other is a method of heating the adhesiveness improver of the carbon material in the liquid medium. This is a method of heating after contacting the surface. Specifically, (1) a liquid dispersant such as solvent or water, a dispersion accelerator composed of the copolymer (A), and a carbon material such as CNT are mixed, and the carbon material is dispersed while heating, and at the same time, carbon. A method for producing a surface-modified carbon material by adhering the copolymer (A) to the surface of the material; (2) The copolymer (A) adheres to the carbon material from the carbon material dispersion liquid obtained in (1) above. Examples thereof include a method of taking out the resulting composite and heating it to produce a surface-modified carbon material.

In the method for producing a surface-modified carbon material according to (1) above, a solvent having a high boiling point, high thermal stability, and no reactivity with an oxazoline group can be used as a dispersant or the like. In order to disperse the carbon material and modify the surface at the same time, the temperature of the dispersion liquid varies depending on the type of carbon material and the composition and structure of the copolymer (A), but is preferably 40 to 200 ° C. and 60 to 60 to 200 ° C. More preferably, it is 180 ° C. If the temperature is lower than 40 ° C, the dispersion time may be longer or the adhesion reaction may not proceed sufficiently, while if the temperature is higher than 200 ° C, lumps of carbon material may be formed or settled. It was difficult to obtain a good dispersion. Further, in this method, since the dispersion of the carbon material and the adhesion reaction with the copolymer (A) proceed simultaneously, it is more preferable to use a stirring device having a mixing effect, an ultrasonic cleaner, a bead mill disperser, or the like. .. The required processing time varies depending on the dispersion method, apparatus and temperature, but is preferably 10 minutes to 10 hours. Further, the obtained surface-modified carbon material may be used in the next step while being dispersed in the dispersion liquid, and can be used after being taken out from the dispersion liquid and waited or dried.

In the method for producing a surface-modified carbon material of (2) above, it is applied as a dispersant or the like to a low boiling point solvent, water, a thermally unstable solvent, or a solvent that reacts with an oxazoline group. In the dispersion step, the temperature is preferably -20 to 40 ° C. and the treatment time is preferably 10 minutes to 10 hours. Further, it is more preferable to use the above-mentioned various dispersion promoting devices. From the obtained dispersion, the carbon material attached to the copolymer (A) is taken out from the dispersion, then dried and heated, and the carboxylic acid group and phenolic hydroxyl group on the surface of the carbon material are converted into the oxazoline group of the copolymer (A). Can be reacted with to obtain a surface-modified carbon material. In addition, in non-nano materials such as long fibrous or pelletized carbon fibers and fine particle carbon black, when it is difficult to prepare a highly dispersed state by a dispersant, the dispersant, copolymer (A) and carbon material may be used. After preparing a uniform mixed solution, the carbon material adhering to the copolymer (A) is taken out from the mixed solution, dried, and heat-treated (baked) to obtain a surface-modified carbon material. The method for separating the carbon material adhering to the copolymer (A) and the dispersant can be performed by one or a combination of two or more methods such as filtration, membrane separation, dialysis, and centrifugation.

The temperature of the firing step is 80 to 240 ° C., preferably 100 to 220 ° C., more preferably 120 to 200 ° C. If the calcination temperature is less than 80 ° C., a low-reactivity substance may not be sufficiently reacted due to the structure of the oxazoline group, and if the calcination temperature exceeds 240 ° C., the copolymer (A) is thermally decomposed. It is not preferable because there is a problem that oxidation and oxidation are likely to occur. The surface-modified carbon material produced by this method is a solid substance and can be used as it is or after being redispersed in a dispersant.

The carbon composite material of the present invention is obtained by reacting a surface-modified carbon material with a solid material. The solid material referred to here includes functional groups that are solid at room temperature and that are reactive with an oxazoline group, such as a carboxyl group, a phenolic hydroxyl group, an acid anhydride functional group, an epoxy group, a thiol group, and an amine group. It is characterized by having one or more functional groups that can be selected from the group consisting of amide groups. These functional groups react with the oxazoline groups on the surface of the surface-modified carbon material, and the generated chemical bonds exist between the surface-modified carbon material and the solid material to provide the effects of cross-linking agents and linking agents.

Examples of the solid material used in the present invention include a thermoplastic resin, a moldable low molecular weight thermosetting resin, and a carbon material. These solid materials may be used alone or in combination. The compounding ratio with the surface-modified carbon material varies depending on the type, structure, physical properties and application of the solid material. For example, applications such as reinforcement of thermoplastic resins and low molecular weight thermosetting resins, addition of antistatic properties, and improvement of heat resistance. If so, 0.01% to 20%, preferably 0.05% to 10% of the surface-modified carbon material can be blended with respect to the thermoplastic resin. Further, it is preferable to dilute a high-concentration product of the surface-modified carbon material as a masterbatch and use it because a more uniform carbon composite material can be easily obtained. On the other hand, for applications such as surface coating, surface modification, and surface modification of carbon materials, 0.001% to 10%, preferably 0.005% to 5% of surface-modified carbon materials are blended with respect to the carbon materials. be able to.

As thermoplastic resins, polyolefins such as polyethylene (PE) and polypropylene (PP), polyamides such as nylon 6 (PA6, nylon 66 (PA66)), polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), Examples thereof include polyurethanes, acrylic resins, ABS (acrylonitrile butadiene styrene) resins, polystyrene (PS), polypropylenes, and thermoplastic resins such as carboxylic acids and maleic anhydride-modified resins of these general-purpose resins. These resins include 1. Not limited to species, multiple types can be used in combination.

Examples of the carbon material include carbon fiber (CF), carbon nanotube (CNT), carbon nanofiber (CNF), graphene, graphite and the like. Among them, CF, CNT, and CNF are widely used in each field, and are preferable because commercially available products are easily available. These carbon materials are not limited to one type, and a plurality of types can be used in combination. Further, these carbon materials may be used as they are on the market, or may be used after being treated by a treatment method such as oxidation to generate many carboxyl groups or phenolic hydroxyl groups on the surface.

Further, the obtained thermoplastic resin-based carbon composite material containing the thermoplastic resin as the main component is reacted with the carbon material or the carbon-based carbon composite material containing the carbon material as the main component, or the carbon material is used as the main component. By reacting the carbon-based carbon composite material to be produced with a thermoplastic resin, a new type of carbon composite material having improved strength and toughness can be produced. From the viewpoint of ensuring sufficient processability and moldability of the new carbon composite material, the compounding ratio of the carbon material or the carbon-based carbon composite material is 10% or less with respect to the thermoplastic resin or the thermoplastic resin-based carbon composite material. Is preferable.

The method for producing a carbon composite material is roughly divided into a solution dipping method and a melt kneading method depending on the structure of the main component. In the dipping method, various organic solvents and water used as the dispersant for the carbon material can be similarly used. Further, the method for producing a carbon composite material by reacting a carbon material with a surface-modified carbon material can be roughly divided into two as described above. One is to disperse the surface-modified carbon material in a liquid medium, immerse the carbon material in the obtained dispersion for a certain residence time, and bring the surface of the carbon material into contact with the surface of the surface-modified carbon material as it is. The method is to heat while rubbing, and the other is to bring the surface of the carbon material into contact with the surface of the surface-modified carbon material, and then take it out of the dispersion liquid and heat it. Further, the reaction between the carbon material and the surface-modified carbon material is to react the oxazoline group possessed on the surface of the surface-modified carbon material with the carboxyl group or phenolic hydroxyl group possessed on the surface of the carbon material. The reaction can be carried out under the same conditions (reaction temperature, reaction time, etc.).

In the method for producing a carbon composite material by melt-kneading, a thermoplastic resin, a thermoplastic resin-based carbon composite material containing a thermoplastic resin as a main component, a surface-modified carbon material and a carbon-based carbon composite containing a carbon material as a main component. Both materials are solid at room temperature, and after dry blending at a predetermined compounding ratio, the reaction may be carried out by melt kneading while heating using a melt extruder or the like. The kneading extrusion temperature varies greatly depending on the type of resin, but if it is within the range of 150 to 280 ° C., both the melting of the resin and the reaction with the carbon material proceed sufficiently, and the carbon composite material to be produced is thermally decomposed. It is preferable because it can prevent. Further, the residence time in the extrusion group is preferably 0.1 to 30 minutes from the viewpoint of balancing reactivity and decomposition suppression.

Further, as the thermoplastic resin used for thermal treatment such as melt-kneading and processing, polyolefins such as polyethylene (PE) and polypropylene (PP), polyamides such as nylon 6 (PA6, nylon 66 (PA66)), and the like. Polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), polyurethanes, acrylic resins, ABS (acrylonitrile butadiene styrene) resins, polystyrene (PS), polycarbonates and carboxylic acids and maleene anhydride of these general-purpose resins Examples thereof include thermoplastic resins such as acid-modified resins. Oxazoline on the surface of the surface-modified carbon material of the present invention so that the properties such as high strength, high flexibility, heat resistance, and conductivity of the carbon material can be fully utilized. Modified PP and polyesters that can react with the group are more preferable. These resins are not limited to one type, and a plurality of types can be used in combination.

Further, from the viewpoint of cost-benefit, it is preferable to use a high-concentration masterbatch. In this case, a masterbatch of the surface-modified carbon material may be prepared first, pelletized and molded, and then kneaded with a thermoplastic resin-based carbon composite material containing various resins or thermoplastic resins as main components.

Examples of the melt kneader used in the melt kneading step include known melt kneaders, such as a Banbury mixer, a plast mill, a lavender plastograph, a uniaxial extruder, and a twin screw extruder. From the viewpoint of satisfactorily dispersing the filler and improving the heat resistance and rigidity of the polyolefin resin composition, it is preferable to melt-knead with a single-screw extruder or a twin-screw extruder, and a twin-screw extruder is particularly preferable.

A twin-screw extruder is typically a raw material supply port, a vent port, a barrel with a jacket, two screws that rotate inside the barrel and rotate in the same direction and in different directions, and a die attached to the tip of the extruder. It consists of a screen mesh. Further, the twin-screw extruder includes at least one melt-kneading portion (kneading portion) composed of a plurality of kneading discs installed in the middle of the screw.

The number of kneading discs constituting one melt-kneading portion (kneading portion) is from the viewpoint of satisfactorily dispersing the filler and from the viewpoint of preventing the polyolefin resin composition from being decomposed by the large heat generated by shearing. Therefore, it is preferably 3 to 200 sheets, and more preferably 5 to 50 sheets. Further, from the viewpoint of preventing the polyolefin resin from decomposing due to the large heat generated by shearing, preferably 1 to 20 units, more preferably 1 to 15 units, with one melt-kneading part (kneading part) as one unit. It is a unit.

The screen mesh is preferably 10 to 500 meshes from the viewpoint of increasing the kneading effect and satisfactorily dispersing the filler and preventing the polyolefin resin composition from being decomposed by the large heat generated by shearing. , More preferably 20-200 mesh.

In the melt extrusion step, if necessary, a known substance generally added to a general-purpose thermoplastic resin, for example, an antioxidant, a heat-resistant stabilizer, an ultraviolet absorber, a lubricant, a pigment, an antistatic agent, a flame retardant, etc. A Japanese agent, a foaming agent, a plasticizer, an anti-bubble agent and the like can be appropriately added.

Applications of the carbon composite material of the present invention include injection molding materials, extrusion molding materials, press molding materials, blow molding materials, film molding materials, and the like, which are manufactured by the melt extrusion method. In particular, it is preferably an application in which rigidity and impact resistance are required, and examples thereof include materials for automobiles and materials for home appliances.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples. In the following, parts and% indicate parts by weight and% by weight, respectively.

The materials used in the examples and comparative examples are as follows. In addition, products that do not specifically describe the manufacturer, purification method, etc. are commercially available products.
<< 2-Oxazoline-based monomer (a) >>
VOZO: 2-Vinyl-2-oxazoline MVOZO: 5-Methyl-2-vinyl-2-oxazoline IPOZO: 2-isopropenyl-2-oxazoline DMVOZO: 4,4'-dimethyl-2-vinyl-2-oxazoline These For the 2-oxazoline-based monomer, Patent Document 5 (Japanese Patent Laid-Open Nos. 2001-058986, 2002-275166, 2004-250391, 2004-238342) which the present inventors have previously applied for. It can be produced by the method described in Japanese Patent Application Laid-Open No. 2004-238343 and Japanese Patent Application Laid-Open No. 2004-238344).
<< Nitrogen-containing heterocyclic monomer (b) >>
NVP: N-vinylpyrrolidone (Tokyo Kasei, reagent)
NVC: N-vinylcaprolactam (Tokyo Kasei, reagent)
"ACMO": N-acryloyl morpholine (manufactured by KJ Chemicals Co., Ltd., trade name "ACMO")
《Carbon material》
CNT: Carbon nanotube (manufactured by Nanocyl, NC-7000, diameter 11 nm, washed with chloroform and dried)
B-CNT: Bead milled CNT (Bead milled: N-methylpyrrolidone 39.8 g, CNT 0.8 g and beads (zirconia Φ0.5 mm) 160 g are added into the vessel of a wet bead mill device (IMEX RMB-08). The beads were milled by stirring at 1000 rpm for 1.5 hours. After that, the solution was put into a 1 L beaker together with the beads, ion-exchanged water was added, and the mixture was shaken lightly to take out the supernatant and float in the supernatant. The carbon nanotubes and the zirconia beads that settle on the bottom were separated. This operation was repeated many times to completely separate the carbon nanotubes and the zirconia beads, and then the supernatant was filtered and vacuum dried at 80 ° C. for 4 hours to obtain a black powder. A bead milled carbon nanotube (B-CNT) was obtained.)
VGCF: Carbon nanofiber (VGCF-H manufactured by Showa Denko KK, diameter 150 nm, washed with chloroform and dried)
CF: Carbon fiber (manufactured by Mitsubishi Rayon Co., Ltd., PAN-based CF, trade name "Pyrofil TR50S15L", diameter 7 μm, washed with chloroform and dried.)
《Others》
MMA: Methyl methacrylate (Tokyo Kasei, reagent)
DMAA: N, N-dimethylacrylamide (manufactured by KJ Chemicals Co., Ltd., trade name "DMAA")
DEAA: N, N-diethylacrylamide (manufactured by KJ Chemicals Co., Ltd., trade name "DEAA")
AIBN: Azobisisobutyronitrile (Wako Pure Chemical Industries, Ltd., reagent)
PVP: Polyvinylpyrrolidone (Tokyo Kasei, reagent, weight average molecular weight 10,000)
NMP: N-methylpyrrolidone EtOH: Ethyl alcohol DMF: N, N-dimethylformamide KJCMPA: 3-Methoxy-N, N-dimethylpropanamide (manufactured by KJ Chemicals, Inc., trade name "KJCMPA")
KJCBPA: 6-methoxy-N, N-dimethylhexaneamide (manufactured by KJ Chemicals Co., Ltd., trade name "KJCBPA")
PP: Polypropylene resin (manufactured by Japan Polypropylene Corporation, MA3)
PMP: Maleic anhydride-modified polypropylene (manufactured by Sanyo Chemical Industries, Ltd., Youmex 1010)
PA: Polymethylpentene resin (manufactured by Mitsui Chemicals, Inc., TPX MX002)
PMA: Acid-modified polymethylpentene resin (manufactured by Mitsui Chemicals, Inc., TPX MM-101B)

The measurement method and evaluation method of various physical properties in Examples and Comparative Examples are as follows.
<< Dispersion >>:
The dispersed state of the produced carbon material dispersion was observed with an optical microscope (Digital Optical Microscope Power Hiscope KH-2700 manufactured by HiROX), the blackness ratio was calculated, and the dispersibility was evaluated in four stages as numerical values. The method for preparing an observation sample and calculating the blackness ratio is as follows.
Sample preparation: Take 5 μL of the dispersion, drop 1 drop on the hole slide glass, and when the flow of the solution has subsided, observe under a microscope and take a photograph.
Calculation of blackness ratio: An optical microscope image (FIG. 1) at 10 arbitrary points was converted into a black-and-white image (FIG. 2), and the blackness ratio was calculated according to formula 1 (the magnification of the image is 100 times). The lower the blackness ratio, the better the dispersibility.
Calculation formula 1
Black ratio (%) = number of black pixels / (number of black pixels + number of white pixels) x 100
⊚: Black ratio is less than 5% ○: Black ratio is 5% or more and less than 10% Δ: Black ratio is 10% or more and less than 15% ×: Black ratio is 15% or more << Dispersion stability (storage stability) ) >>:
Using the prepared carbon material dispersion, the mixture was allowed to stand at 25 ° C. for 90 days, the state thereafter was observed with an optical microscope, the blackness ratio was calculated, and the dispersibility was evaluated as a numerical value in the same four stages as described above.

<< Synthesis of copolymerization (A) >>
Synthesis Example 1
VOZO 25.0 g (257.7 mmol), NVP 85.9 g (773.0 mmol), azobisisobutyronitrile (AIBN) in a 500 mL reaction vessel equipped with a stirrer, thermometer, cooler and dry nitrogen inlet tube. ) 1.7 g (10.3 mmol) and 260 mL of toluene were charged, and the reaction solution was stirred at 30 ° C. for 60 minutes under a dry nitrogen stream, and then the polymerization reaction was carried out at 90 ° C. for 8 hours. After completion of the reaction, the temperature was returned to room temperature, the highly viscous reaction solution was diluted with 50 mL of chloroform, and poured into an excess amount of hexane (about 2 L) to obtain a white precipitate. Then, the precipitate was filtered and vacuum dried at 50 ° C. for 3 hours to obtain 101.8 g of a white powdery solid (yield = 91.8%).
In the white powdery solid, absorption peculiar to the oxazoline group (1650 cm ^-1 ) and absorption peculiar to the pyrrolidone group (1700 cm ^-1 ) were detected by the infrared absorption spectrum (IR), and these monomers were derived. Absorption of vinyl group (990 cm ^-1 ) was not detected, and the formation of copolymer (A-1) was confirmed. Further, the composition of the copolymer was confirmed by ¹ H-NMR (CDCl ₃ ) analysis as VOZO-derived unit / NVP-derived unit = 1.0 / 2.3, and further, the weight average molecular weight (Mw) of the copolymer was confirmed. ) Was analyzed by the GPC method (standard polystyrene) and confirmed to be 2650.

Synthesis Examples 2 to 10 and Synthesis Comparative Examples 1 to 3
Similar to Synthesis Example 1, 2-oxazoline-based monomer (a), nitrogen-containing heterocyclic monomer (b), other copolymerizable vinyl-based monomer (c), and AIBN are shown in Table 1. Polymerization of Synthesis Examples 2 to 8 and Comparative Examples 1 to 3 was carried out using an amount, and the obtained polymer was purified in the same manner as in Synthesis Example 1 and the respective polymers (A-2 to A-10 and P) were purified. -1 to P-3) were obtained as a white powder. Synthesis As in Example 1, identification (IR) of polymers A-2 to A-10 and polymers P-1 to P-3, molecular weight measurement (GPC), and composition ratio calculation ( ^{1 1} H-NMR) are performed, and the yield is obtained. It is shown in Table 1 together with the rate.

As shown in Table 1, the composition ratio of the obtained copolymer is slightly different from the molar ratio of the monomers charged in the polymerization reaction. That is, it can be confirmed that the 2-oxazoline-based monomer (a) is contained in the copolymer in a larger amount than the charge. It is considered that this is because the monomer (a) has higher reactivity to radicals during polymerization than the nitrogen-containing heterocyclic monomer (b), and the obtained copolymer (A) is a monomer (A). It is suggested that the random sequences of a) and (b) have a partial block structure, and since it has such a unique structure, it is possible to provide an excellent dispersion promoting effect, adhesiveness improving effect, etc. to the carbon material. The present inventors speculate.

<< Preparation of carbon material dispersant >>
Dispersion Examples 1-12, Dispersion Comparative Examples 1-6
The copolymer and the dispersant were mixed at the ratios shown in Table 2 and treated at 25 ° C. for 30 minutes using a bath-type ultrasonic device (manufactured by ELMA, S30) to obtain a mixed solution. A predetermined amount of carbon material shown in Table 2 was added to the mixed solution and treated at 25 ° C. for 120 minutes using a bath-type ultrasonic device to prepare a carbon material dispersion. The dispersibility and dispersion stability of the obtained dispersion were evaluated by the above method, and the results are shown in Table 2. Further, the state immediately after the preparation of the dispersions of Dispersion Examples 1 and 2, the state after the dispersions of Dispersion Example 2 were allowed to stand for 90 days, the optics of the dispersions of Dispersion Comparative Example 1, Dispersion Comparative Example 4 and Dispersion Comparative Example 5. Micrographs are shown in FIGS. 3-8.

From the results of the dispersion examples and the dispersion comparative examples, the carbon material could not be uniformly dispersed when the copolymer (A) of the present invention was not contained. On the other hand, a homopolymer of a 2-oxazoline-based monomer (a) (dispersion comparative example 1), a homopolymer of a nitrogen-containing heterocyclic monomer (b) (dispersion comparative example 4), and a mixture thereof (dispersion comparative example 6) are blended. Even in this case, the carbon material could not be uniformly dispersed or reaggregation was likely to occur, and a stable dispersion could not be obtained. That is, when the copolymer of the specific composition of the monomer (a) and the monomer (b) proposed in the present invention is used as the dispersion accelerator, the dispersibility and the dispersion stability are satisfied, and the dispersion is uniform and stable. The liquid could be obtained.

<< Preparation of surface-modified carbon material >>
1. 1. Simultaneous heating method The copolymer (A) of the present invention can be used as a dispersion accelerator for carbon materials and at the same time as an adhesive improver for carbon materials. At this time, the dispersion accelerator / adhesiveness improver composed of the copolymer (A) promotes the dispersion of the carbon material in the liquid medium, and then the copolymer is heated while being in contact with the surface of the carbon material. The oxazoline group of (A) reacts with the carboxyl group or phenolic hydroxyl group on the surface of the carbon material, and the copolymer (A) is fixed (adhered) to the surface of the carbon material via a chemical bond to modify the surface of the carbon material. Is manufactured. In particular, when a solvent having a high boiling point and not reactive with an oxazoline group is used as a dispersant, a surface-modified carbon material can be easily produced by this method.

Example 1 of surface-modified carbon material production (Modification Example 1)
Dispersion The dispersion obtained in Example 1 was transferred to a flask and heated at 120 ° C. for 1 hour with stirring. Then, the dispersant was removed by vacuum evaporation, and the unreacted copolymer (A) was removed by washing twice with ethanol using a lab shaker (200 rpm, 15 minutes / once). The washed solid was dried under vacuum to obtain surface-modified CNTs (AC-1) in the form of solid powder. Using about 5 mg of the obtained AC-1, weigh it with a thermogravimetric analyzer (Q-600, TA INSTRUMENT), raise the temperature from room temperature to 600 ° C at 10 ° C / min under a nitrogen atmosphere, and reduce the heat weight to AC. The amount of the copolymer (A) adhered to the surface of -1 was calculated to be 3.52%. Furthermore, based on the physical properties of CNT (density 2 g / cm ³ , diameter 11 nm), it was confirmed that the amount of copolymer adhered per surface area was 0.200 mg / m ² .

Examples 2 to 5 and Comparative Examples 1 to 4 for producing a surface-modified carbon material (Modified Examples 2 to 5 and Modified Comparative Examples 1 to 4)
A surface-modified carbon material was prepared using the dispersions obtained in the above-mentioned dispersion examples 4, 7, 8 and 11 in the same manner as in the modified example 1, and the surface-modified CNTs (AC-2 to 5) in the form of solid powder were prepared. ) Was acquired. Further, using the mixed solutions prepared in Dispersion Comparative Examples 1 and 4 to 6, PC-1 to 4 were obtained as powdery solids by the same operation as in Modified Example 1. Similarly, the polymer and the like adhered to the surface of the carbon material are quantified by thermogravimetric analysis, and the calculation results are shown in Table 3.

Examples 6 to 8 and Comparative Examples 5 to 7 for producing a surface-modified carbon material (Modified Examples 6 to 8 and Modified Comparative Examples 5 to 7)
The copolymer (A) and the dispersant (solvent) were mixed at the ratios shown in Table 4 and treated at 25 ° C. for 30 minutes using a bath-type ultrasonic device (ELMA, S30) to obtain the copolymer. A solution was obtained. A predetermined amount of carbon material (CF, appropriately cut into 1 mm to 2 cm) shown in Table 4 was added to the solution, and heating was performed under the predetermined conditions (temperature and time) shown in Table 4. Then, the obtained solid material is filtered, washed twice with ethanol using a lab shaker (200 rpm, 15 minutes / time), and the washed solid material is dried under vacuum to form a solid powder surface. Modified CF (AC-6-8) was obtained.
Using 3 mg each of the obtained AC-6 to 8, the amount of the copolymer (A) adhered to the surface was calculated by thermogravimetric analysis in the same manner. Furthermore, based on the physical property values of CF (density 2 g / cm ³ , diameter 7 μm), the amount of copolymer adhesion per surface area was calculated and shown in Table 4.
Further, in the same manner as in Modified Example 6, Preparation of Modified Comparative Examples 5 to 7 was carried out according to the conditions shown in Table 4, and PC-5 to 7 was obtained as a powdery solid. Similarly, the amount of polymer adhered per surface area of PC-5 to 7 was calculated by thermogravimetric analysis and is shown in Table 4.

Examples 9 and 10 and Comparative Example 8 for producing a surface-modified carbon material (Modified Examples 9 and 10 and Modified Comparative Example 8)
2. 2. Post-heating method When the copolymer (A) of the present invention is used as an adhesive improver for a carbon material, the copolymer (A) is dissolved in a liquid medium (organic solvent or water) and then the carbon material is added. The copolymer (A) is attached to the surface of the carbon material, and then the carbon material to which the copolymer (A) is attached is taken out from the solution and heated, so that the oxazoline group of the copolymer (A) is formed on the surface of the carbon material. The copolymer (A) is fixed (adhered) to the surface of the carbon material via a chemical bond by reacting with the carboxyl group and the phenolic hydroxyl group of the above, and a surface-modified carbon material is produced. In particular, when a solvent having a low boiling point or reactivity with an oxazoline group is used, or when it is difficult to prepare a dispersion liquid of a large-sized carbon material, the surface-modified carbon material can be easily produced by this method.

A predetermined amount of carbon material (CF, appropriately cut into 1 mm to 2 cm) was added to the copolymer solution shown in Table 4, and the mixture was treated with a bath-type ultrasonic device at 25 ° C. for 30 minutes. After that, the solid matter is filtered and heat-treated (baked) under the predetermined conditions shown in Table 4, and ethanol washing is carried out twice in the same manner, the washed solid matter is dried, and the surface-modified CF in the form of a solid powder. (AC-9) was acquired.
Further, a carbon material (CF 3 m) cut into a length of 3 m is passed through the copolymer solution shown in Table 4 at a rate of 1 mm / sec through a copolymer solution tank having a width of 300 mm, and heated under the predetermined conditions shown in Table 4. The treatment (baking) is performed, and then the same width ethanol bath is passed twice (2 mm / sec) to dry the washed fibrous solid to obtain a solid fibrous surface-modified CF (AC-10). did.
Further, in the same manner as in Modified Example 9, the modified Comparative Example 8 was prepared according to the conditions in Table 4, and PC-8 was obtained as a powdery solid. Similarly, the amount of polymer adhered to the surface area of PC-8 was calculated by thermogravimetric analysis and is shown in Table 4.

<< Fabrication and evaluation of carbon composite materials >>
Using the surface-modified carbon material of the present invention, the unreacted oxazoline group in the copolymer adhered to the surface is utilized to further react with the solid carbon material, the thermoplastic resin or a mixture thereof. The following three types of carbon composite materials can be produced.
(1) Carbon composite material (carbon / copolymer / carbon) consisting of carbon material and surface-modified carbon material
Similar to the production of surface-modified carbon materials, this type of composite material can be reacted by heating while contacting the carbon material with the surface-modified carbon material in a liquid medium, or the carbon material and the surface in a liquid medium. A post-heating method in which the material is brought into contact with the modified carbon material and then reacted by heating can be mentioned.
(2) Carbon composite material (resin / copolymer / carbon) consisting of a thermoplastic resin and a surface-modified carbon material
This type of composite material can be produced by a melt-kneading method in which a surface-modified carbon material and a general-purpose resin are dry-blended and the resin reacts in a molten state while being in contact with the surface-modified carbon material by a melt extruder or the like. This method is preferable because the obtained carbon composite material can be directly formed.
(3) Carbon composite material (resin / carbon / copolymer / carbon) composed of thermoplastic resin, carbon material and surface-modified carbon material
This type of carbon composite material can be produced by dry-blending a surface-modified carbon material with a carbon material and a general-purpose resin and then reacting them by melt-kneading, and the "carbon / copolymer" obtained in (1) above. It can also be produced by melt-kneading a "polymer / carbon" type carbon composite material with a general-purpose resin.

Examples 1 and 2 of carbon composite material production (composite examples 1 and 2)
CF and NMP appropriately cut into the surface-modified carbon material AC-1, 1 mm to 2 cm obtained in Example 1 of producing the surface-modified carbon material were weighed at a weight ratio of 1:10:89 and used by a bath-type ultrasonic device. Treatment was performed at 25 ° C. for 30 minutes. After that, the mixed solution was heated at 150 ° C. for 0.5 hour, the obtained black solid was separated by filtration, and washed twice with ethanol using a lab shaker (200 rpm, 15 minutes / time). The subsequent solid was dried under vacuum to obtain a solid carbon composite material (CAC-1).
Further, the solid matter is separated by filtration without heating the above-mentioned mixed solution after ultrasonic treatment, washed and dried in the same manner as described above, and heated at 180 ° C. for 0.2 hours to obtain a solid carbon composite material (CAC). -2) was acquired. The surface condition of the untreated cut product CF and the surface condition of the solid separated by filtration after the heat treatment before and after the ethanol cleaning were observed with a scanning electron microscope (FE-SEM, JEOLJIS-6700F), respectively. The photographs of are shown in FIGS. 9 to 11.

Examples 3 and 4 of carbon composite material production (composite examples 3 and 4)
The surface-modified carbon materials AC-1 and NMP were weighed at a weight ratio of 2:98 and treated with a bath-type ultrasonic device at 25 ° C. for 30 minutes. After that, the mixed solution was heated to 150 ° C., and a carbon material (CF 3 m) cut into a length of 3 m was passed through a tank filled with the mixed solution having a width of 300 mm at a speed of 0.5 mm / sec, and an ethanol tank having the same width was passed. Was passed twice (2 mm / sec), and the washed fibrous solid was dried to obtain a solid fibrous carbon composite material (CAC-3).
Further, the carbon material (CF 3 m) cut into a length of 3 m was passed through a tank filled with the mixed solution having a width of 300 mm at a speed of 1 mm / sec without heating the mixed solution after the sonication treatment, and the temperature was 200 ° C. The fibrous solid material after washing was dried by passing it through an ethanol tank of the same width twice (2 mm / sec) by heating for 0.1 hour in a solid fibrous carbon composite material (CAC-4). ) Was acquired.

Examples 5 and 6 of carbon composite material production (composite examples 5 and 6)
Using the surface-modified carbon material AC-2 obtained in Example 2 for producing the surface-modified carbon material, Examples 5 and 6 were carried out based on the predetermined conditions shown in Table 5, and a solid carbon composite material (CAC-5) was performed. , 6) was acquired.

Comparative Examples 1 to 4 for Fabrication of Carbon Composite Material (Composite Comparative Examples 1 to 4)
Comparative Examples 1 to 4 were carried out according to the conditions shown in Table 5 according to the procedure of Examples 1 to 6 for producing a carbon composite material, and a solid or fibrous carbon composite material (CPC-1 to 4) was obtained. In CPC-4, CNT and CF are directly adhered to each other without any copolymer or the like.

In the obtained CAC-1 to 6 and CPC-1 to 4, the weight increase of CF due to adhesion or adhesion of the surface-modified carbon material or the like is calculated from the weight of CF before and after the production of the carbon composite material, and is shown in Table 5.
In addition, SEM photographs of CAC-3, CPC-1, 2 and 4 are shown in FIGS. 12 to 15.

From the results of Table 5 and FIGS. 9 to 15, it is clear that the carbon composite material formed via the copolymer (A) of the present invention has CNTs firmly coated on the surface of CF. Further, the carbon composite material of the present invention can be produced by various methods such as simultaneous heating and post-heating, and the oxazoline group contained in the copolymer (A) is highly reactive and the formed chemical bonds are formed. It is strong and adheres sufficiently even if it comes into contact with a carbon material such as CF (Fig. 9) at room temperature, and is further adhered by heating (Fig. 10), and even if it is washed, only the amount adhered to the surface is removed and adhered by chemical bonding. The weight gain rate was calculated from the weight of the carbon composite material after washing and drying (FIG. 11). Further, when a homopolymer of 2-vinyl-oxazoline (FIG. 13) is used with respect to the carbon composite material (FIG. 12) using the copolymer (A), CNTs are uniformly dispersed and adhered to the CF surface. When PVP (Fig. 14) is used and when nothing is used as a dispersion promoter or adhesiveness improver (Fig. 15), neither CNT adhesion nor adhesion is confirmed on the CF surface, and CF and CNT are not confirmed. It turned out that the complex of

Examples 7 to 12 (Composite Examples 7 to 12) and Comparative Examples 5 to 9 (Composite Comparative Examples 5 to 8) for producing a carbon composite material.
Using PP, PMP, PA and PMA as general-purpose resins, dry-blend the surface-modified carbon material of the present invention and the carbon / copolymer / carbon-based carbon composite material with the composition shown in Table 6 and batch-type biaxial kneading. Using a machine (Laboplast Mill μ manufactured by Toyo Seiki Co., Ltd.), melt-kneading was performed under the predetermined conditions shown in Table 6 to obtain resin / copolymer / carbon-based and resin / carbon / copolymer / carbon-based. A carbon composite material was prepared. The obtained carbon composite materials were formed into a disc by a hot press machine, and then the disc was completely frozen by immersing the disc in liquid nitrogen for 2 minutes. The frozen disk was broken by bending, and the fracture surface was observed by SEM. In addition, 20 SEM photographs of the fracture surface of one disc were taken, a total of 150 fibers were counted, and the number of fibers to which the resin was attached was calculated as the ratio of the total fibers to 150 fibers as the resin adhesion rate, and Table 6 Shown in.
Further, the obtained carbon composite material was used in a hot press machine (miniTEST PRESS-10 manufactured by Toyo Seiki Co., Ltd.) to prepare a film having a thickness of 200 μm (molding temperature 235 ° C., pressure 5 MPa for 2 minutes). After that, it was rapidly cooled in 1 minute to prepare a press film.) The obtained press film was punched out from a dumbbell test piece having a length of 35 mm and a width of 2.5 mm, and a tensile tester (manufactured by Toyo Seiki Co., Ltd.) with a chuck distance of 15 mm. It was fixed to a universal testing machine) and a tensile test was performed at a speed of 10 mm / min. In each Example and Comparative Example, the average value of the tensile strengths of the five test pieces is taken and shown in Table 6.
SEM photographs of the fracture surface of the frozen disk of Composite Examples 7 and 10 are shown in FIGS. 16 and 17. In addition, a cross-sectional SEM photograph of the tensile test piece of Composite Example 11 is shown in FIG.

From the results of Table 6 and FIGS. 16 to 18, the carbon / resin-based carbon composite material formed via the copolymer (A) of the present invention was modified with the copolymer on the surface of CF or CNT. Adhesion (adhesion rate of resin) to polyolefin-based general-purpose resins and their acid-modified resins is improved, and in particular, resin / CNT obtained by adding CNT / copolymer / CF-based carbon composite material to general-purpose resin. It was confirmed that the / copolymer / CF-based composite material was further enhanced in strength by imparting a reinforcing effect by CNT / copolymer / CF (FIG. 18). On the other hand, the effect of improving the adhesiveness of PVP, 2-vinyl-oxazoline homopolymers, or a mixture thereof is low, and especially when there is nothing between CF and CNT, no adhesiveness-imparting or reinforcing effect is shown. It was.

Photograph for dispersibility evaluation Photograph for dispersion evaluation (black and white) Dispersion Example 1 Photograph immediately after preparation of dispersion Dispersion Example 2 Photograph immediately after preparation of dispersion Dispersion Example 2 Photograph of the dispersion liquid after standing for 90 days Dispersion Comparative Example 1 Photograph immediately after preparation of dispersion Dispersion Comparative Example 4 Photograph immediately after preparation of dispersion Dispersion Comparative Example 5 Photograph immediately after preparation of dispersion Surface photograph of untreated cut product CF Surface photograph of Composite Example 2 before cleaning Surface photograph immediately after cleaning of Composite Example 2 Surface photograph of carbon composite material of composite example 3 Surface photograph of the material produced in Composite Comparative Example 1 Surface photograph of the material produced in Composite Comparative Example 2 Surface photograph of the material produced in Composite Comparative Example 4 Composite Example 7 Photograph of fracture surface of frozen disk Composite Example 10 Photograph of fracture surface of frozen disk Composite Example 11 Photograph of cross section of tensile test piece

The copolymer of the present invention exhibits peculiar performance in promoting the dispersion of carbon materials in other materials and improving the surface adhesiveness of carbon materials, and the dispersion promoters and adhesiveness improvers of carbon materials containing them are It does not require special dispersion or surface treatment technology or equipment, does not impair the original characteristics of the carbon material, and can impart hydrophilicity and adhesiveness to the surface of various carbon materials by a simple method. Further, the carbon material whose surface is modified by using the adhesiveness improver (surface-modified carbon material) can be easily produced by industrial means, and is peculiar by reacting with various solid materials using the carbon material. Suitable carbon composite materials with performance can be provided. The various carbon composite materials obtained in the present invention can be expected to remarkably improve thermal properties, impact resistance and rigidity while maintaining high mechanical properties of general-purpose resins such as polyolefins, and are used in various industrial fields. As various engineering plastics, especially bumpers, instrument panels, console boxes, roof sheets, panel packaging materials, interior and exterior parts related to automobiles and transportation equipment such as electrical components, daily necessities related products such as home appliances, furniture, miscellaneous goods, molded products of medical materials, etc. Suitable for packaging materials such as food containers, food packaging, general packaging, coating materials such as electric wires and cables, industrial materials such as construction / civil engineering, stationery / office supplies, compatibilizers or adhesives for various polymer alloys. Is.

Claims (12)

2-oxazoline vinyl monomer (a). 1 to 90 mol%, nitrogen-containing heterocyclic vinyl monomer (b) 10 to 99 mole% and a copolymer adhesion promoting agent for carbon materials using (A) met An adhesive improver for carbon materials, which is characterized by the presence of a chemical bond between the copolymer (A) and the carbon material. The adhesive improver for a carbon material according to claim 1, wherein the nitrogen-containing heterocyclic vinyl monomer (b) is vinylpyrrolidone. The adhesive improver for a carbon material according to claim 1, wherein the carbon material is a carbon nanotube and / or a carbon fiber. A surface-modified carbon material characterized in that the surface is modified via a chemical bond by the adhesiveness improver according to any one of claims 1 to 3 . The surface-modified carbon material according to claim 4 , wherein the surface contains 0.1 to 100 mg / m ^{2 of} an adhesiveness improver. By heating the adhesiveness improver according to any one of claims 1 to 3 in a liquid medium (excluding water) while contacting the surface of the carbon material, the adhesiveness improver is carbonized via a chemical bond. A method for producing a surface-modified carbon material, which comprises fixing to the surface of the material. After the adhesiveness improver according to any one of claims 1 to 3 is brought into contact with the surface of the carbon material in a liquid medium, the carbon material having the adhesiveness improver attached to the surface is taken out and heated to adhere. A method for producing a surface-modified carbon material, which comprises fixing the property improver to the surface of the carbon material via a chemical bond . A carbon composite material composed of the surface-modified carbon material and the solid material according to claim 4 or 5 , and the solid material includes a carboxyl group, a phenolic hydroxyl group, an acid anhydride functional group, an epoxy group, a thiol group, and an amine. It has one or more functional groups that can be selected from the group consisting of groups and amide groups, and is characterized by the presence of a chemical bond formed by reacting with the oxazoline group of these functional groups between the surface-modified carbon material and the solid material. Carbon composite material. The carbon composite material according to claim 8, wherein the solid material is a carbon material. The carbon composite material according to claim 8, wherein the solid material is a carbon nanotube and / or a carbon fiber. The carbon composite material according to claim 8, wherein the solid material is a thermoplastic resin. The carbon composite material according to claim 8, wherein the solid material is a carbon material and a thermoplastic resin.