JP6617229B2 - Oxazoline dispersants for carbon materials and carbon composite materials using them - Google Patents

Description

  The present invention relates to a dispersion accelerator for carbon materials, an adhesion improver, a sizing agent for fibrous carbon materials, a surface-modified carbon material and a carbon composite material modified to these.

  Many carbon materials are generally composed of carbon atoms, and show various forms and functions depending on the bonding mode and aggregation mode of carbon atoms. Among them, graphite, fullerene, carbon nanotube, carbon nanohorn, carbon nanobrush, fullerene , 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, sports equipment, tires), catalyst carriers, electrode materials (dry cells, fuel cells), Widely used as molecular sieve membranes, adsorbents for water purification, deodorants, cosmetics, shampoos, face masks, surface coats, electromagnetic shielding materials, heat dissipation materials, pharmaceuticals (adsorbents).

  Since carbon materials have a 6-membered ring structure of carbon atoms and are not polar, they have poor wettability and dispersibility for general-purpose materials and have insufficient adhesion to matrix resins. Surface hydrophilization treatment has been carried out by conventional methods. For example, in carbon fiber, by introducing an amino group on the surface, the adhesiveness with the epoxy resin is improved (Non-patent Document 1), and the epoxy resin and 1,3-phenylenebis-2-2 are used as a sizing agent on the surface. It was reported that fuzzing could be prevented by attaching oxazoline (Patent Document 1), and further, a fiber sizing agent containing an acrylic resin and an aqueous medium was reported from a polyoxyalkylene group and an amide group or cyano group. (Patent Document 2). On the other hand, in the 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, oxygen-containing functional groups such as hydroxyl groups are introduced to the surface by using strong acid treatment at high temperatures or ultraviolet irradiation in the presence of hydrogen peroxide using diamond powder and fine particles, and in general solvents such as water and alcohol. A method for producing a diamond that can be stably dispersed has been disclosed (Patent Documents 3 and 4).

  Carbon nanotubes (CNT) have a fibrous structure with a diameter of several to several tens of nanometers and a length of several to several hundreds of micrometers, and have been actively studied as a typical nano-sized carbon material in recent years. CNT has a very large aspect, so it exhibits excellent electrical, thermal and mechanical properties, but it is very easy to get entangled, and not only for general-purpose resin and metal, but also for similar carbon matrix However, wettability, interfacial adhesion and adhesion are poor, and a high-performance composite material utilizing the characteristics of CNTs has not yet been obtained.

  In order to develop a highly functional composite material, several techniques have been disclosed for surface modification of CNTs. 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. In Non-Patent Document 4, heat treatment (2000 ° C.) is performed on CNTs, surface treatment is performed using hydrogen peroxide and ultraviolet rays, and then a resin composite material using polycarbonate as a base material is produced. A method to improve the mechanical strength of the steel was proposed. However, since these CNT surface modification methods are performed under vacuum or ultra-high temperature conditions, special equipment is required, and it cannot be said that they are industrial production methods from the viewpoint of equipment and cost. .

  On the other hand, a technique has been proposed in which CNT is not particularly treated, and the resin combined with CNT has a special specification. In Patent Document 5, in the first step, a polymer having an oxazoline group in the side chain, a thermoplastic resin and a modified thermoplastic resin are melt-kneaded at 180 ° C. for 10 minutes by a twin-screw extruder, and a resin composition for filler dispersion is obtained. I got a thing. In the second step, the filler-dispersed resin composition obtained in the first step and the CNT filler are melt-kneaded again at 180 ° C. for 10 minutes using a twin-screw extruder to obtain a thermoplastic resin exhibiting conductivity. It has been disclosed that a complex has been obtained. This method is effective for a specific thermoplastic resin, but is not compatible with a high melting point or heat decomposable thermoplastic resin, a polymer having an oxazoline group in the side chain or a modified thermoplastic resin, or a thermosetting resin. In addition, since metal-based materials, carbon materials, and the like cannot be melt-kneaded, a filler-dispersing resin composition cannot be obtained, and the composite with CNT is not as expected.

Carbon, 2000, No. 195, 336-340 The Chemical Society of Japan, 1993, No. 6, 746-751 Nagano Prefectural Institute of Technology, 2006, No. 1, M10-M15 Proc. Of the 2013 JSPE Spring Conference, 659-660

JP-A-5-132874 JP 2014-152428 A Japanese Patent Laid-Open No. 9-025110 JP 2012-046378 A JP 2014-149164 A

  The present invention does not require special dispersion and surface treatment techniques and equipment, and does not impair the original characteristics of the carbon material, and can facilitate imparting hydrophilicity and adhesion to the surface of various carbon materials by a simple method. It is an object of the present invention to provide a sizing agent, an adhesion improver, and a sizing agent for a fibrous carbon material, and to provide a carbon material (surface modified carbon material) whose surface is modified using the adhesion improver. The adhesion improver and the surface-modified carbon material can be produced in high yield by industrial means, and by using these, a suitable carbon composite material having specific performance can be obtained by reacting with various solid materials. The subject is to provide.

  As a result of intensive studies to solve these problems, the present inventors have found that a co-polymer containing 2-oxazoline monomer (a) and low Tg (glass transition temperature) vinyl monomer (b) as constituent units. It has been found that the polymer exhibits unique properties for promoting the dispersion of carbon materials into other types of materials, improving the surface adhesion of carbon materials, and imparting the convergence of fibrous carbon materials. Moreover, the surface modification carbon material to which adhesiveness was provided was able to be acquired by making it react with various carbon materials using the adhesive improvement agent which consists of the said copolymer. Furthermore, carbon with excellent mechanical properties, good heat resistance, wear resistance, heat dissipation, and conductivity by reacting with general-purpose carbon materials and thermoplastic resins using adhesion improvers and surface-modified carbon materials A composite material can be obtained, and the above problems have been solved and the present invention has been achieved.

That is, the present invention
(1) 2-oxazoline monomer (a) 5 to 98 mol% and vinyl monomer (b) 2 to 95 mol% having a glass transition temperature (Tg) of the homopolymer of −100 to 80 ° C. as structural units Containing copolymer (A),
(2) The vinyl monomer (b) having a glass transition temperature (Tg) of the homopolymer of −100 to 80 ° C. is an alkoxy (poly) alkylene glycol (meth) acrylate, described in (1) above A copolymer (A) of
(3) An aqueous dispersion in which the copolymer (A) according to (1) or (2) is dispersed in water,
(4) A dispersion accelerator for carbon material using the copolymer (A) according to (1) or (2),
(5) The carbon material dispersion accelerator according to (4), wherein the carbon material is a carbon nanotube,
(6) An adhesion improver for a carbon material using the copolymer (A) according to (1) or (2),
(7) A surface-modified carbon material that is surface-modified with the adhesion improver according to (6),
(8) The surface-modified carbon material according to (7) above, which contains 0.1 to 100 mg / m ^{2 of} an adhesion improver on the surface,
(9) A sizing agent for a fibrous carbon material using the copolymer (A) according to (1) or (2),
(10) A method for producing a surface-modified carbon material, which is heated after impregnating the carbon material in the aqueous dispersion according to (2),
(11) A carbon composite material comprising the surface-modified carbon material according to (7) or (8) and a solid material, and the solid material includes a carboxyl group, a phenolic hydroxyl group, an acid anhydride functional group, an epoxy Having at least one functional group 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 between the surface-modified carbon material and the solid material Carbon composite material, characterized by
(12) The carbon composite material according to (11), wherein the solid material is a carbon material,
(13) The carbon composite material according to (11), wherein the solid material is a thermoplastic resin,
(14) The carbon composite material according to (11), wherein the solid material is a carbon material and a thermoplastic resin.

  The copolymer (A) of the present invention comprises a vinyl monomer (b) 2 having a 2-oxazoline monomer (a) 5 to 98 mol% and a homopolymer glass transition temperature (Tg) of −100 to 80 ° C. 95 mol% is contained as a structural unit. If the contents of (a) and (b) are within this range, the resulting copolymer (A) is a homopolymer of a 2-oxazoline monomer, a vinyl monomer having a Tg of −100 to 80 ° C. Compared to homopolymers and mixtures of these homopolymers (blend polymers), specific effects were confirmed both as a dispersion promoter for carbon materials, as an adhesion improver, and as a sizing agent for fibrous carbon materials. It was. The composition and structure of the polymer are unclear as to the causal relationship with the specific effect, but the inventor believes that the effect is higher when the (a) and (b) of the present invention are partially arranged in blocks. Guess.

  The copolymer (A) of the present invention has flexibility derived from a low Tg (-100 ° C to 80 ° C) vinyl monomer and an oxazoline group highly reactive with a carboxylic acid or a phenolic hydroxyl group on the surface of a carbon material. Even a carbon material having a large aspect such as CNT can be easily dispersed in water, an organic solvent, or a plastic resin, and re-aggregation is suppressed, so that a stable dispersed state can be maintained. In addition, excellent convergence can be provided for the fibrous carbon material.

  By using the copolymer (A) of the present invention as an adhesion improver and reacting with various carbon materials under mild conditions, the adhesion improver is uniformly covered on the surface of the carbon material, and the carbon material is removed. A surface-modified carbon material that is not separated can be easily produced by an industrial technique. In addition, since the surface-modified carbon material obtained has an unreacted oxazoline group on the surface, various solid materials, for example, the same or different carbon materials, carboxyl groups that can react with oxazoline groups, phenolic hydroxyl groups, acid anhydrides Specific properties that combine the characteristics of carbon and resin materials by reacting with a solid thermoplastic resin having one or more functional groups selected from the group consisting of functional groups, epoxy groups, thiol groups, amine groups and amides It is possible to easily obtain a carbon composite material having.

Hereinafter, the present invention will be described in detail.
The copolymer (A) of the present invention is characterized by containing a 2-oxazoline monomer (a) and a vinyl monomer (b) having a Tg of −100 to 70 ° C. as constituent units. Since the vinyl monomer (b) has a low Tg and high flexibility, it exhibits the effect of promoting the dispersion of the carbon material in organic or inorganic liquids or solids in other types of materials, and has an oxazoline group. Has a high reactivity with the carboxylic acid or phenolic hydroxyl group on the surface of the carbon material, and can prevent re-aggregation of the carbon material once dispersed, thereby providing a stable dispersion effect. The copolymer (A) contains (a) and (b) at a specific blending ratio, that is, (a) contains 5 to 98 mol% and (b) contains 2 to 95 mol%. Is preferred. If the content of (a) is less than 5 mol%, there is a risk that reaggregation after dispersion may not be sufficiently suppressed in a carbon material having a very large aspect such as CNT, and when used as an adhesion improver. Since it is difficult to cover the entire surface of the carbon material uniformly and uniformly, there is a possibility that a sufficient effect of improving adhesiveness cannot be obtained. On the other hand, when the content of (a) exceeds 98 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 2 mol% or more, a good dispersion state is formed also in various carbon materials, and if the content of (b) exceeds 95 mol%, the content of reactive oxazoline groups Cannot be sufficiently ensured, and there is a problem that the dispersion stability and adhesion improving effect and the carbon fiber focusing effect cannot be satisfied. The copolymer of the present invention, and the dispersion accelerator, adhesion improver and sizing agent of the fibrous carbon material obtained therefrom are the reaggregation suppressing effect and the adhesion improving effect due to the reactivity of the oxazoline group of (a), (b) Therefore, it is considered that excellent dispersibility, dispersion stability, adhesion improvement, and focusing effect can be maximized. In addition, the copolymer (A) is not only uniformly arranged on the surface of the carbon material, but also strongly bonded to the carbon material through a chemical bond formed by a chemical reaction, and reacts with the hydrophilicity on the surface of the carbon material. Therefore, the most specific effect that can be provided as the adhesion improver of the present invention is that it easily adheres to the surface of the carbon material and does not leave semipermanently.

  2-Oxazoline monomers (a) are 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, 4,4-diethyl-2-isopropenyl-2-oxazoline, 4,5-dimethyl-2-isopropenyl-2-oxazoline, 4,5-diethyl-2 -One or more monomers selected from the group consisting of isopropenyl-2-oxazoline. Among these 2-oxazoline monomers, 2-vinyl-2-oxazoline, 2-isopropenyl- having high reactivity with functional groups such as a carboxyl group, a phenolic hydroxyl group, an acid anhydride group, and a thiol group. 2-oxazoline, 5-methyl-2-vinyl-2-oxazoline, and 4,4-dimethyl-2-vinyl-2-oxazoline are preferable, and 2-vinyl-2-oxazoline and 2-isopropenyl-2-oxazoline are more preferable. Most preferred.

  The low Tg vinyl monomer (b) is a vinyl monomer having a glass transition temperature (Tg) of -100 to 70 ° C., specifically, methyl acrylate (Tg: 8 ° C.), acrylic acid. Ethyl (Tg: -22 ° C), butyl acrylate (Tg: -54 ° C), 2-ethylhexyl acrylate (Tg: -70 ° C), octyl acrylate (Tg: -65 ° C), nonyl acrylate (Tg: -58 ° C), dodecyl acrylate (Tg: -3 ° C), cyclohexyl acrylate (Tg: 15 ° C), 2-hydroxy-3-phenoxypropyl acrylate (Tg: 17 ° C), ethyl methacrylate (Tg: 65 ° C) ), N-butyl methacrylate (Tg: 20 ° C.), isobutyl methacrylate (Tg: 48 ° C.), 2-ethylhexyl methacrylate (Tg: −10 ° C.) (Meth) acrylic acid alkyl esters such as octyl crylate (Tg: -20 ° C), dodecyl methacrylate (Tg: -65 ° C), cyclohexyl methacrylate (Tg: 66 ° C), 2-hydroxyethyl acrylate (Tg: -15 ° C), 2-hydroxypropyl acrylate (Tg: -7 ° C), 4-hydroxybutyl acrylate (Tg: -40 ° C), 2-hydroxyethyl methacrylate (Tg: 55 ° C), 1,4- Hydroxyalkyl (meth) acrylate such as cyclohexanedimethanol monoacrylate (Tg: 18 ° C), methoxyethyl acrylate (Tg: -50 ° C), ethoxyethyl acrylate (Tg: -50 ° C), methoxybutyl acrylate (Tg:- 56 ° C), 3-methoxypropyl acrylate (Tg: -75 ° C), butoxy Tyl acrylate (Tg: -40 ° C or lower), phenoxydiethylene glycol acrylate (Tg: -25 ° C), methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, butoxypolyethylene glycol (meth) acrylate, octoxypolyethylene glycol (Meth) acrylate, lauroxy polyethylene glycol (meth) acrylate, stearoxy polyethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, phenoxy polyethylene glycol-polypropylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, Nonylphenoxypolypropylene glycol (meth) acrylate Oxyalkylene group-containing monomers such as Nylate, nonylphenoxypolyethylene glycol (meth) acrylate, nonylphenoxyethylene glycol-polypropylene glycol (meth) acrylate, octoxypolyethylene glycol-polypropylene glycol (meth) acrylate, and alkoxy (poly) alkoxy glycol ( (Meth) acrylate, methyl vinyl ether (Tg: −31 ° C.), ethyl vinyl ether (Tg: −43 ° C.), propyl vinyl ether (Tg: −49 ° C.), butyl vinyl ether (Tg: −55 ° C.), isobutyl vinyl ether (Tg: − 19 ° C.), alkyl vinyl ethers such as 2-ethylhexyl vinyl ether (Tg: −66 ° C.) and dodecyl vinyl ether (Tg: −62 ° C.). These can be used alone or in combination of two or more.

  Among these low Tg vinyl monomers (b), water-soluble and hydrophilic ones are preferred when an aqueous dispersion is produced by dispersing the resulting copolymer (A) in water. The aqueous dispersion mentioned here is an aqueous solution in which the copolymer (A) is dissolved in water and / or a dispersion in which the copolymer (A) is dispersed in water.

  The copolymerization method of the 2-oxazoline monomer (a) and the low Tg vinyl 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 bulk polymerization in an organic solvent such as alcohol and ethyl acetate. When the solution polymerization method in an organic solvent is employed, as a polymerization solvent, toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl alcohol, ethyl alcohol, or the like can be used alone or in combination.

  Examples of the polymerization initiator used for the copolymerization include generally known polymerization initiators such as azo, organic peroxide, inorganic peroxide, and redox. As the usage-amount of a polymerization initiator, it is about 0.001-10 mol% normally with respect to the polymerizable monomer component total amount. Further, a normal radical polymerization technique such as adjustment of molecular weight by a chain transfer agent is applied.

  Further, the 2-oxazoline monomer (a) and the low Tg vinyl monomer (b) can be subjected to multi-component copolymerization with other copolymerizable vinyl monomers as constituent units. Other copolymerizable vinyl monomers include (meth) acrylates having an alkyl group having 1 to 12 carbon chains, N-alkyl (meth) acrylamides having an alkyl group having 1 to 12 carbon chains, the same or different N, N-dialkyl (meth) acrylamide having two carbon chain 1-12 alkyl groups, (meth) acrylate or (meth) acrylamide having an aromatic substituent, hydroxyalkyl (C1-12) (meth) acrylate or (Meth) acrylamide, (meth) acrylonitrile, (meth) acrylic acid and the like can be mentioned. These copolymerizable vinyl monomers may be used alone or in combination of two or more. The total molar fraction of various other copolymerizable vinyl monomers to be blended is 30 It is preferable that it is below mol%.

  The molecular weight of the copolymer (A) of the present invention is 1,000 to 500,000 on a weight average basis. Moreover, Preferably it is 1,500-100,000, More preferably, it is 2,000-80,000. When the weight average molecular weight is less than 1,000, initial dispersion failure of a hardly dispersible carbon material such as CNT may occur, and uneven adhesion to the carbon material surface is likely to occur as an adhesion improver, As a sizing agent for a fibrous carbon material, a sufficiently satisfactory effect may not be achieved, which is not preferable. On the other hand, when the weight average molecular weight exceeds 500,000, the viscosity of the copolymer solution or dispersion obtained by dissolving and dispersing in the liquid dispersant is remarkably increased, and as a result, the dispersibility and surface adhesion of the carbon material are lowered. There was a tendency to.

  The glass transition temperature (Tg) of the copolymer (A) of the present invention is −80 to 75 ° C. Moreover, Preferably it is -70-70 degreeC, More preferably, it is -50-65 degreeC. If the Tg is less than -80 ° C, the strength of the copolymer (A) may be significantly reduced and may not be suitable for use as an adhesion improver. On the other hand, if the Tg exceeds 75 ° C, the copolymer The flexibility of (A) is insufficient and it is easy to peel off from the surface of the carbon material due to friction or the like, and the carbon fiber bundled as a sizing agent may become hard and workability may be lowered. When the carbon composite material is formed, the affinity with the resin is insufficient, and the mechanical strength of the resulting composite material cannot be satisfied, which is not preferable.

The glass transition temperature (Tg) of the copolymer (A) is a value calculated based on the well-known Fox formula below. When the copolymer (A) is composed of n types of monomer components of monomer 1, monomer 2, ..., monomer n,
1 / Tg = W1 / Tg1 + W2 / Tg2 + ... + Wn / Tgn
(In the formula, Tg is the glass transition temperature (unit: K) of the copolymer (A), and Tgi (i = 1, 2,... N) is the glass transition temperature when the monomer i forms a homopolymer ( (Unit: K), Wi (i = 1, 2,..., N) represents a weight (mass) fraction of all monomer components of monomer i.)
In the present invention, “glass transition temperature when homopolymer is formed” means “glass transition temperature of homopolymer of the monomer”.

  The carbon material used in the present invention is a material mainly composed of carbon (carbon material), and can be broadly divided into carbon fibers and nanocarbon materials. Examples of carbon fibers include polyacrylonitrile (PAN), pitch, rayon, and plant-derived materials. Nanocarbon materials include fullerenes, carbon nanotubes (CNT), vapor-grown carbon fibers (nano Fiber), graphene, graphite, carbon nanoparticles, diamond, artificial diamond, nanodiamond particles, graphite, and other nanocarbons. Among them, PAN-based carbon fiber is more preferable as a fiber system because it is excellent in strength per unit weight and elastic modulus and has a large production amount, and CNT can control the structure at the nanometer level, and is inexpensive and industrially useful as a new functional material. Since it can be manufactured at a level, it is preferable as a nano-based carbon material. Moreover, even if these carbon materials are used as they are on the market, they may be used after a treatment for producing a large number of carboxyl groups and phenolic hydroxyl groups on the surface by a treatment method such as oxidation.

  The carbon materials used in the present invention may be used singly or in combination of two or more according to their respective purposes. In addition, these carbon materials can be used as they are on the market, but physical dispersion treatments such as washing with water and solvents, bead mill dispersion treatment and ultrasonic dispersion treatment for entanglement of CNTs are implemented. The use after that is more preferable.

  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, 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 (DMS) ), Cyclohexane, alkoxy -N, N-dialkyl propanamide, polyhydric alcohols, silicone oils, cationic, anionic, can be used widely, such as zwitterionic or non-ionic surfactants. Moreover, it is good also as a mixture of arbitrary combination ratios which consist of a combination of any one or more of these, or a water-soluble organic solvent and water.

  In the above solvent dispersant, especially in molecules such as NMP, NMF, DMF, DMSO, “KJCMPA” (3-methoxy-N, N-dimethylpropanamide, “KJCMPA” is a registered trademark of KJ Chemicals Co., Ltd.) A hydrophilic solvent having a nitrogen atom or a sulfur atom in the above has a strong interaction with the copolymer (A) of the present invention, thereby having an effect of preventing reaggregation of a carbon material such as CNT, and is stable. Since a dispersion liquid is easy to be formed, it is preferable. Further, when water is used as a dispersant, there is an environmentally friendly merit because it does not have an organic solvent to be discarded. At that time, by adding the copolymer (A) of the present invention as a dispersion accelerator, the dispersibility of the carbon material that is difficult to disperse in water is improved, and an environmentally friendly dispersion of the carbon material is easily obtained. be able to.

The copolymer (A) of the present invention has a blending amount as a carbon material dispersion accelerator, an adhesion improver, and a sizing agent for a fibrous carbon material. Although it varies greatly depending on the presence and absence and the method, 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 (CNT) 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. ² is more preferable.

  If the blending amount of the copolymer (A) is less than 0.01% by mass with respect to the dispersant, there may be a problem in that it cannot be sufficiently dispersed depending on the type and concentration of the carbon material. Even when the liquid is obtained, when the carbon material is subsequently adhered to the solid material using the dispersion, the effect as an adhesion improver cannot be sufficiently provided, and a uniform and high strength carbon material adhesion layer can be obtained. There is a possibility that there is no possibility, or when used as a sizing agent for a fibrous carbon material, fiber fluffing or yarn breakage may occur, and there is a possibility that a satisfactory sizing effect cannot be obtained. 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, but the adhesion improver When it is used as a fibrous carbon fiber, it is not preferable because the concentration is high and the physical properties are likely to vary.

In the present invention, the carbon material can be adhered to the solid material by using the obtained carbon material dispersion, and the fibrous carbon material can be focused. Furthermore, when the blending amount of the copolymer (A) as an adhesion improver or a sizing agent is 0.1 to 100 mg / m ² with respect to the carbon material, the carbon material is adhered uniformly and with high strength to a solid material. Or can uniformly cover the carbon fiber, which is preferable.

  The dispersion promoter for carbon materials, the adhesion improver for carbon materials, and the sizing agent for fibrous carbon materials of the present invention are all characterized by containing a copolymer (A). The copolymers (A) contained therein may have the same composition and structure, or may have different compositions and structures, and can be used alone or in combination. Further, from the viewpoint of low cost and easy process control, it is preferably a dispersion accelerator and at the same time, an adhesion improver and a sizing agent for fibrous carbon materials.

  The method for producing a surface-modified carbon material according to the present invention includes a dispersion accelerator, an adhesion improver, a type of sizing agent for fibrous carbon material (hereinafter abbreviated as a dispersion accelerator, etc.), a carbon material, an adhesion improver, and a sizing agent. It can be roughly divided into two types according to the reaction method. One is a method in which an adhesion improver or sizing agent comprising a copolymer (A) is heated in contact with the surface of a carbon material in a liquid medium, and the other is an adhesion improver or sizing agent. It is the method of heating after making it contact the surface of the carbon material in a liquid medium. Specifically, (1) a liquid dispersant such as a 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 of producing a surface-modified carbon material by adhering the copolymer (A) to the surface of the material; (2) The copolymer (A) is attached to the carbon material from the carbon material dispersion obtained in (1) above. A method of taking out the composite and producing a surface-modified carbon material by heating can be mentioned.

  In the method for producing a surface-modified carbon material according to (1), a solvent having a high boiling point and high thermal stability and having no reactivity with an oxazoline group can be used as a dispersant or the like. In order to simultaneously disperse the carbon material and modify the surface, the temperature of the dispersion step varies depending on the type of carbon material and the composition and structure of the copolymer (A), but is preferably 40 to 200 ° C., 60 to It is more preferable that it is 180 degreeC. When the temperature is lower than 40 ° C., the dispersion time may be prolonged or the reaction for adhesion or modification may not proceed sufficiently. On the other hand, when the temperature is higher than 200 ° C., a lump of carbon material is generated or settled. It was difficult to obtain a stable dispersion. In this method, since the carbon material dispersion and the reaction for adhering to or modifying the copolymer (A) proceed at the same time, a stirrer having a mixing effect, an ultrasonic cleaner, a bead mill disperser, or the like is used. Is more preferable. The required treatment time varies depending on the dispersion method, apparatus and temperature, but it is preferably 10 minutes to 10 hours. Furthermore, the obtained surface-modified carbon material may be used in the next step while being dispersed in the dispersion, and can be used after being taken out from the dispersion and weighted or dried.

  In the method for producing a surface-modified carbon material of (2) above, the present invention is applied to a low-boiling solvent, water, a thermally unstable or solvent that reacts with an oxazoline group as a dispersant. In the dispersing step, it is preferable that the temperature is -20 to 40 ° C and the treatment time is 10 minutes to 10 hours. Moreover, it is more preferable to use the above various dispersing devices. Thereafter, the carbon material with the copolymer (A) attached to the surface is taken out of the dispersion and dried by heating, and the carboxylic acid group or phenolic hydroxyl group on the surface of the carbon material is converted into the oxazoline group of the copolymer (A). To obtain a surface-modified carbon material. In addition, in a non-nano-based material such as long-fiber or pellet-like carbon fiber or fine-particle carbon black, it is difficult to prepare a highly dispersed state with a dispersant, the dispersant, copolymer (A), and carbon material After preparing a uniform mixed solution, the surface-modified carbon material can be obtained by taking out the carbon material to which the copolymer (A) is attached from the mixed solution, drying and heating (baking). The carbon material to which the copolymer (A) is attached can be separated from the dispersant by one or a combination of two or more methods such as filtration, membrane separation, dialysis, and centrifugation.

  The temperature of a baking process is 40-240 degreeC, 60-220 degreeC is preferable and 80-200 degreeC is more preferable. If the calcination temperature is less than 40 ° C., there is a possibility that those having low reactivity cannot react sufficiently due to the structure of the oxazoline group, and if the calcination temperature exceeds 240 ° C., thermal decomposition of the copolymer (A) And oxidation are likely to occur, which is not preferable. The surface-modified carbon material produced by this method is a solid 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 a reaction between a surface-modified carbon material and a solid material. The solid material referred to here is a functional group that is solid at room temperature and has reactivity with the 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 at least one functional group selected from the group consisting of amide groups. These functional groups react with the oxazoline group on the surface of the surface-modified carbon material, and the generated chemical bond exists between the surface-modified carbon material and the solid material, thereby providing the effect of a crosslinking agent or a linking agent.

  Examples of the solid material used in the present invention include thermoplastic resins, moldable low molecular weight thermosetting resins, and carbon materials. 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, improvement of heat resistance, etc. If so, 0.01 to 80% by mass, preferably 0.05 to 70% by mass of the surface-modified carbon material can be blended with respect to the thermoplastic resin. Moreover, since a more uniform carbon composite material is easy to be obtained by diluting and using a high concentration product of a surface-modified carbon material as a master batch, it is preferable. On the other hand, in the case of applications such as surface coating, surface modification, and surface modification of a carbon material, 0.001 to 20% by mass, preferably 0.005 to 10% by mass of a surface modified carbon material is added to the carbon material. be able to.

  Polyolefins such as polyethylene (PE) and polypropylene (PP) as thermoplastic resins, polyamides such as nylon 6 (PA6, nylon 66 (PA66), polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), Examples include polyurethanes, acrylic resins, ABS (acrylonitrile butadiene styrene) resins, polystyrene (PS), thermoplastic polyimide, polycarbonates, and thermoplastic resins such as carboxylic acid and maleic anhydride modified resins of these general-purpose resins. Examples of the low molecular weight thermosetting resin include phenol resin, epoxy resin, polyimide resin, melamine resin, urea resin, unsaturated polyester resin, diallyl phthalate resin, polyurethane resin, and silicon resin. Et resin is not limited to one, may be used in combination of plural kinds.

  Examples of the carbon material include carbon fiber (CF), carbon nanotube (CNT), carbon nanofiber (CNF), graphene, graphite, natural or synthetic diamond. Among them, CF, CNT, CNF, diamond particles and powders are widely used in various fields, and it is 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. Moreover, even if these carbon materials are used as they are on the market, they may be used after a treatment for producing a large number of carboxyl groups and phenolic hydroxyl groups on the surface by a treatment method such as oxidation.

  In addition, the obtained thermoplastic resin-based carbon composite material having a thermoplastic resin as a main component and a carbon material or a carbon-based carbon composite material having a carbon material as a main component are reacted, or the carbon material is a main component. By reacting the carbon-based carbon composite material with the thermoplastic resin, a new carbon composite material with improved strength and toughness can be produced. From the viewpoint of sufficiently ensuring the workability and moldability of the new carbon composite material, the compounding ratio of the carbon material or the carbon-based carbon composite material is 80% by mass or less with respect to the thermoplastic resin or the thermoplastic resin-based carbon composite material. Preferably there is.

  The method for producing a carbon composite material is roughly divided into a solution immersion 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 a dispersant for the carbon material can be used as well. Moreover, the carbon material and the surface-modified carbon material can be reacted, and the method for producing the carbon composite 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 liquid for a certain residence time, and directly contact the surface of the carbon material and the surface of the surface-modified carbon material, The other is a method of heating while rubbing, and the other is a method in which the surface of the carbon material and the surface of the surface-modified carbon material are brought into contact with each other and then taken out from the dispersion and heated. 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 similar conditions (reaction temperature, reaction time, etc.).

  In the above-mentioned method for producing a carbon composite material by melt kneading, a thermoplastic resin, a thermoplastic resin-based carbon composite material mainly composed of a thermoplastic resin, a carbon-based carbon composite mainly composed of a surface-modified carbon material and a carbon material Both materials are solid at room temperature, and after dry blending at a predetermined blending ratio, a reaction may be performed 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. Can be prevented, which is preferable. Moreover, it is preferable that it is 0.1 to 30 minutes about the residence time in an extrusion group from a viewpoint of balance of reactivity and decomposition suppression similarly.

  Further, as thermoplastic resins 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), 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 maleic anhydrides of these general-purpose resins And thermoplastic resins such as acid-modified resins, etc. Oxazoline on the surface of the surface-modified carbon material of the present invention so that the properties of the carbon material such as high strength, high flexibility, heat resistance, and conductivity can be fully utilized. Modified PP and polyesters that can react with groups Preferred. These resins not limited to one type may be used in combination of plural kinds.

  Furthermore, it is preferable to use a high-concentration masterbatch from the viewpoint of work convenience. In this case, a master batch of a surface-modified carbon material may be first prepared and pelletized and then kneaded with a thermoplastic resin-based carbon composite material mainly containing various resins and thermoplastic resins.

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

  Examples of the use of the carbon composite material of the present invention include materials for injection molding, materials for extrusion molding, materials for press molding, materials for blow molding, materials for film molding and the like in those manufactured by the melt extrusion method. In particular, it is preferably an application that requires rigidity and impact resistance, and examples thereof include materials for automobiles and materials for household appliances.

  The molding of the carbon composite material of the present invention also applies various molding methods used for ordinary CFRP (plastic reinforced with carbon fiber). For example, as a wet molding method, a molding method (hand lay-up method) in which a reinforcing material such as carbon fiber is charged in advance in a mold and the resin is impregnated with a brush or roller and laminated to a predetermined thickness while defoaming (hand layup method), roving Molding method (filament winding method) in which resin is impregnated, tension is applied to a rotating core bar (mandrel), and is continuously wound at a predetermined angle (mold winding method), and chopped strand preformed with a cavity core mold and matrix are pressed by cold press The method (cold press method) and the molding method (RTM method) in which a preform (preliminary molded body formed only with a reinforcing material) is placed in a mold, the mold is closed and a matrix is injected and cured (dry method) are mentioned. As above, arrange the intermediate base material in one type (mainly core type), keep the periphery secret and perform vacuum suction, and heat at 130-250 ° C Molding method (autoclave method), sheet winding method suitable mainly for cylindrical shape, molding method in which an intermediate base material impregnated with resin in chopped strands and coated on both sides with gin sheet is charged to the mold and heated and pressurized ( SMC method), a molding method (BMC method) in which an intermediate base material kneaded with chopped strands and a matrix is made into a lump (ball shape), a molding method (hot press method) in which heat and pressure is applied with a cavity core mold, a stamped sheet The RFI (Resin Film Infusion) method, the CPM (Compression Press Molding) method, etc. are mentioned.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. In the following, parts and% indicate parts by weight and% by weight, respectively.

The materials used in Examples and Comparative Examples are as follows. In addition, those that do not particularly describe the manufacturer, purification method, etc. are commercially available products.
<< 2-oxazoline monomer (a) >>
VOZO: 2-vinyl-2-oxazoline (Tg of homopolymer: 108 ° C.)
MVOZO: 5-methyl-2-vinyl-2-oxazoline IPOZO: 2-isopropenyl-2-oxazoline DMVOZO: 4,4′-dimethyl-2-vinyl-2-oxazoline << low Tg vinyl monomer (b) >>
MTG-A: Methoxytriethylene glycol acrylate (manufactured by Kyoeisha Chemical Co., Ltd., homopolymer Tg: −50 ° C.)
M-20G: Methoxydiethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., homopolymer Tg: −51 ° C.)
M-40G: Methoxypolyethylene glycol 400 methacrylate (EO 4 mol) (manufactured by Shin-Nakamura Chemical, Tg of homopolymer: -67 ° C)
AM-90G: Methoxypolyethylene glycol 400 acrylate (EO 9 mol) (manufactured by Shin-Nakamura Chemical, Tg of homopolymer: -71 ° C.)
M-90G: Methoxypolyethylene glycol 400 methacrylate (EO 9 mol) (manufactured by Shin-Nakamura Chemical, Tg of homopolymer: −69 ° C.)
M-230G: Methoxypolyethylene glycol 400 methacrylate (EO 23 mol) (manufactured by Shin-Nakamura Chemical, Tg of homopolymer: −52 ° C.)
<< Other vinyl monomers (c) >>
“DMAA”: dimethylacrylamide (manufactured by KJ Chemicals, registered trademark “DMAA”)
"DEAA": Diethylacrylamide (manufactured by KJ Chemicals, registered trademark "DEAA")
《Carbon material》
CNT: Carbon nanotube (Nanocyl, NC-7000, diameter 11 nm, washed with chloroform and dried)
B-CNT: Bead mill treatment CNT (bead mill treatment: 39.8 g of N-methylpyrrolidone, 0.8 g of CNT and 160 g of beads (Zirconia φ0.5 mm) were added into a vessel of a wet bead mill apparatus (IMB RMB-08). Then, the beads were milled by stirring at 1000 rpm for 1.5 hours, and then all the beads were put in a 1 L beaker, ion-exchanged water was added and shaken lightly, and the supernatant was removed to float in the supernatant. This process was repeated many times to completely separate the carbon nanotubes and zirconia beads, and the supernatant was filtered and vacuum-dried at 80 ° C. for 4 hours to obtain a black powder. A bead mill-treated carbon nanotube (B-CNT) was obtained.)
VGCF: Carbon nanofiber (VGCF-H manufactured by Showa Denko KK, diameter 150 nm, washed with chloroform and dried)
CF1: Carbon fiber (manufactured by Toray Industries, Inc., PAN-based CF, trade name “TORAYCA Yarn T700 12K”, diameter 7 μm) Washed with acetone and dried.
CF2: CF1 was cut into 5 mm chops, washed with acetone and dried.
<General-purpose resin>
PP: Polypropylene resin (Nippon Polypro Co., Ltd., MA3)
PMP: maleic anhydride modified polypropylene (manufactured by Sanyo Chemical Industries, Ltd., Umex 1010)
PA: Polymethylpentene resin (manufactured by Mitsui Chemicals, TPX MX002)
PMA: acid-modified polymethylpentene resin (manufactured by Mitsui Chemicals, TPX MM-101B)
<Others>
AIBN: Azobisbutyronitrile (Wako Pure Chemicals, Reagents)
NMP: N-methylpyrrolidone EtOH: ethyl alcohol DMF: N, N-dimethylformamide “KJCMPA”: 3-methoxy-N, N-dimethylpropanamide (registered trademark “KJCMPA” manufactured by KJ Chemicals)

The measurement methods and evaluation methods for various physical properties in Examples and Comparative Examples are as follows.
<< Dispersibility >>
The dispersion state of the produced carbon material dispersion was observed with an optical microscope (manufactured by HiROX, digital optical microscope power high scope KH-2700), the black ratio was calculated, and the dispersibility was evaluated in four stages. In addition, preparation of the sample for observation and the calculation method of a black rate are 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 stops, perform microscopic observation and take a photograph.
Black rate calculation: An optical microscope image at 10 arbitrary points was converted into a black and white image (FIG. 1), and the black rate was calculated according to the calculation formula 1 (the magnification of the image is 100 times). The lower the black rate, the better the dispersibility.
Formula 1
Black rate (%) = number of black pixels / (number of black pixels + number of white pixels) × 100%
A: Black ratio is less than 5% B: Black ratio is 5% or more and less than 10% Δ: Black ratio is 10% or more and less than 15% X: Black ratio is 15% or more << Dispersion stability (storage stability) ) >>:
Using the produced carbon material dispersion, it was allowed to stand at 25 ° C. for 90 days, the subsequent state was observed with an optical microscope, the black rate was calculated, and the dispersibility was evaluated in four steps as described above.

<< Synthesis of Copolymerization (A) >>
Synthesis Example 1
VOZO 36 g (371 mmol), AM-90G 58 g (128 mmol), azobisisobutyronitrile (AIBN) 0.8 g (5 mmol) in a 500 mL reaction vessel equipped with a stirrer, thermometer, condenser and dry nitrogen introduction tube. ), 220 mL of ethyl acetate was charged, and the reaction solution was stirred at 30 ° C. for 60 minutes under a dry nitrogen stream, and then polymerization reaction was performed at 70 ° C. for 12 hours. After completion of the reaction, the temperature was returned to room temperature, and the viscous reaction solution was poured into hexane (about 2 L) to obtain a pale yellow precipitate. Thereafter, the supernatant was discarded, and the precipitate was washed twice with hexane, followed by vacuum drying at 40 ° C. for 3 hours to obtain 87.5 g of a light yellow viscous liquid product (yield = 92.1). %).
From the infrared absorption spectrum (IR) of the product, an absorption peculiar to the oxazoline group derived from VOZO (1660 cm ⁻¹ ) and an absorption peculiar to the ester group derived from AM-90G (1730 cm ⁻¹ ) are detected. Absorption of vinyl groups derived from these monomers (1635 to 1640 cm ⁻¹ ) was not detected, confirming the production of copolymer (A-1). The composition of the copolymer was confirmed by ¹ H-NMR (CDCl ₃ ) analysis to be VOZO-derived unit / AM-90G-derived unit = 3.0 / 1.0, and the Tg of the copolymer (A-1) was − It calculated as 26 degreeC. Furthermore, the weight average molecular weight (Mw) of the copolymer was analyzed by GPC method (standard polystyrene) and confirmed to be 20,670. A ¹ H-NMR (CDCl ₃ ) chart of the copolymer (A-1) is shown in FIG.

Synthesis Examples 2 to 10 and Synthesis Comparative Examples 1 to 4
As in Synthesis Example 1, 2-oxazoline monomer (a) and low Tg vinyl monomer (b), other copolymerizable vinyl monomers (c), and AIBN in predetermined amounts shown in Table 1 Polymerization of Synthesis Examples 2 to 10 and Synthesis Comparative Examples 1 to 4 was performed, and the obtained polymer was purified in the same manner as in Synthesis Example 1. The respective polymers (A-2 to A-10 and P -1 to P-4) were obtained as a solid product from a pale yellow viscous liquid. As in Synthesis Example 1, the identification (IR), Tg analysis, molecular weight measurement (GPC), and composition ratio calculation ( ¹ H-NMR) of the polymers A-2 to A-10 and the polymers P-1 to P-4 were performed. The results are shown in Table 1.

  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 monomer (a) is contained in the copolymer more than charged. This is presumably because the monomer (a) is more reactive to radicals during polymerization than the low Tg vinyl monomer (b), and the resulting copolymer (A) contains monomer ( It is suggested that the random arrangement of a) and (b) has a partial block structure, and since it has such a unique structure, it is possible to provide a dispersion promoting effect and an adhesion improving effect that are superior to carbon materials. The present inventors presume.

<< Production of carbon material dispersion >>
Dispersion Examples 1-16, Dispersion Comparative Examples 1-8
The copolymer and the dispersant were mixed at a ratio shown in Table 2, and treated at 25 ° C. for 30 minutes using a bath-type ultrasonic device (EL30, S30) to obtain a mixed solution. A predetermined amount of the 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 resulting dispersion were evaluated by the above methods, and the results are shown in Table 2. Moreover, the optical microscope photograph immediately after preparation of the dispersion liquid of dispersion Examples 2 and 5 (dispersion liquids 2 and 5) and dispersion comparison examples 1 to 3 (dispersion comparison liquids 1 to 3) is shown in FIG.

  From the results of the dispersion examples and the dispersion comparison examples, when a dispersion accelerator is not contained (dispersion comparison examples 1 and 5), or when a low Tg vinyl monomer (b) homopolymer (dispersion comparison example 3) is used, The carbon material could not be uniformly dispersed in water or an organic solvent-based dispersant. On the other hand, a homopolymer of 2-oxazoline monomer (a) (dispersion comparative example 2), a copolymer (dispersion comparative example 4) having a content of 2-oxazoline monomer (a) of less than 5 mol%, and 2-oxazoline When the content of the monomer (a) exceeds 98 mol% (dispersion comparative example 7), and homopolymers and mixtures of these copolymers (dispersion comparative examples 6 and 8), can the carbon material be dispersed uniformly? Re-aggregation was likely to occur, and a stable dispersion could not be obtained. That is, only when the copolymer of the specific composition consisting of the monomer (a) and the monomer (b) proposed in the present invention is used as a dispersion accelerator, the dispersibility and the dispersion stability can be satisfied, and it is uniform and stable. A dispersion could be obtained.

<Production of surface-modified carbon material>
1. Simultaneous Heating Method The copolymer (A) of the present invention can be used as a carbon material dispersion accelerator and simultaneously as an adhesion improver for carbon materials and as a sizing agent for fibrous carbon materials. At this time, the dispersion accelerator / adhesion improver made of the copolymer (A) in the liquid medium promotes the dispersion of the carbon material, and then is heated while being in contact with the surface of the carbon material. The oxazoline group of (A) reacts with a carboxyl group or phenolic hydroxyl group on the surface of the carbon material, and the copolymer (A) is fixed to the surface of the carbon material through a chemical bond, thereby producing a surface-modified carbon material. be able to.

Example 1 of surface-modified carbon material production (Modification Example 1)
The dispersion obtained in Dispersion Example 1 was transferred to a flask and heated at 100 ° C. for 1 hour with stirring. Thereafter, the dispersant was removed by reduced pressure evaporation, and washing was performed twice with ethanol using a lab shaker (200 rpm, 15 minutes / once) to remove the unreacted copolymer (A). The solid after washing was dried under vacuum to obtain solid powdered surface modified CNT (AC-1). About 5 mg of the obtained AC-1 was weighed with a thermogravimetric analyzer (Q-600, TA INSTRUMENT) and heated from room temperature to 600 ° C. at a temperature of 10 ° C./minute in a nitrogen atmosphere. The adhesion amount of the copolymer (A) adhered to the surface of -1 was calculated to be 5.24%. Furthermore, based on the physical property values (density 2 g / cm ³ , diameter 11 nm) of CNTs, it was confirmed that the copolymer adhesion amount per surface area was 0.300 mg / m ² .

Examples 2 to 8 and Comparative Examples 1 to 6 for producing surface-modified carbon materials (Modified Examples 2 to 8 and Modified Comparative Examples 1 to 6)
In the same manner as in Modification Example 1, using the dispersion obtained in each of the above dispersion examples, a surface-modified carbon material was prepared, and solid powdery surface-modified CNTs (AC-2 to 8) were obtained. Moreover, PC-1 to 6 were obtained as a powdery solid by the same operation as in Modification Example 1 using the mixed solution prepared in each dispersion comparative example. Similarly, polymers attached to the surface of the carbon material were quantified by thermogravimetric analysis, and the calculation results are shown in Table 3.

Examples 9 to 12 and Comparative Examples 7 to 9 for producing surface-modified carbon materials (Modified Examples 9 to 12 and Modified Comparative Examples 7 to 9)
The copolymer (A) and the dispersant (solvent) were mixed in the ratio shown in Table 4, and treated with a bath-type ultrasonic device (ELMA, S30) at 25 ° C. for 30 minutes. A solution was obtained. A predetermined amount of carbon material (CF, appropriately cut to 1 mm to 2 cm) shown in Table 4 was added to the solution, and heating was performed under predetermined conditions (temperature and time) shown in Table 4. Thereafter, the obtained solid is filtered, washed with ethanol twice using a lab shaker (200 rpm, 15 minutes / once), and the washed solid is dried under vacuum to obtain a solid powdery surface. The modified carbon material (AC-9-12) was obtained. Using 3 mg each of the obtained AC-9 to 12, the adhesion amount of the copolymer (A) adhered to the surface was similarly calculated by thermogravimetric analysis. Further, based on the physical properties of CF (density 2 g / cm 3, diameter 7 μm), the amount of copolymer adhering per surface area was calculated and shown in Table 4.
Moreover, similarly to the modification example 9, preparation of the modification comparative examples 7-9 was performed according to the conditions shown in Table 4, and PC-7-9 was acquired as a powdery solid substance. Similarly, the polymer adhesion amount per surface area of PC-7 to 9 was calculated by thermogravimetric analysis and is shown in Table 4.

2. Post-heating method The copolymer (A) of the present invention dissolves the copolymer (A) in a liquid medium (organic solvent or water) when used as an adhesion improver for carbon materials and a sizing agent for fibrous carbon materials. After the carbon material is added, the copolymer (A) is attached to the surface of the carbon material, and then the carbon material attached to the copolymer (A) is taken out of the solution and heated to produce the copolymer (A ) Reacts with a carboxyl group or a phenolic hydroxyl group on the surface of the carbon material, and the copolymer (A) is fixed to the surface of the carbon material through a chemical bond to produce a surface-modified carbon material. 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 of a large size carbon material, the surface-modified carbon material can be easily produced by this method.

Examples 13 to 15 and Comparative Example 10 for producing surface-modified carbon materials (Modified Examples 13 to 15 and Modified Comparative Example 10)
A predetermined amount of a carbon material (CF, appropriately cut to 1 mm to 2 cm) was added to the copolymer solution shown in Table 4, and treated at 25 ° C. for 30 minutes with a bath-type ultrasonic device. Thereafter, the solid material is filtered and subjected to heat treatment (firing) under the predetermined conditions shown in Table 4. Similarly, ethanol washing is performed twice, the washed solid material is dried, and solid powdery surface-modified carbon is obtained. Material (AC-13) was obtained.
In addition, a carbon material (CF 3 m) cut to a length of 3 m was passed through the copolymer solution shown in Table 4 through a copolymer solution tank having a width of 300 mm at a speed of 1 mm / second, and heated under predetermined conditions shown in Table 4 Treatment (baking) is performed, and then the ethanol bath having the same width is passed twice (2 mm / second), the washed fibrous solid is dried, and the solid fibrous surface-modified carbon material (AC-14, 15) ).
Further, as in Modification Example 13, Preparation of Modification Comparative Example 10 was performed according to the conditions in Table 4 to obtain PC-10 as a powdery solid. Similarly, the polymer adhesion amount per surface area of PC-10 was calculated by thermogravimetric analysis, and is shown in Table 4.

Example 1 of evaluation of sizing agent for fibrous carbon material (Bundling example 1)
Carbon material CF1 cut to a length of 6 cm is dipped in an aqueous solution of copolymer (A-1) (concentration 1% by weight), impregnated for 5 minutes at room temperature, and then removed from the aqueous solution at a rate of 0.03 mm / second. The sizing CF bundle (SAC-1) was obtained by pulling up and placing in a vacuum dryer set at 100 ° C. and performing heat treatment for 1 hour under vacuum. Using about 3 mg of the obtained SAC-1, similarly, the weight of the copolymer adhered to the fiber bundle by thermogravimetric analysis was calculated to be 0.72, and the physical property value of CF1 (the amount per surface area by weight% was calculated). Based on the physical property values of CF1 (density 2 g / cm ³ , diameter 7 μm), it was confirmed that the copolymer adhesion amount per surface area was 25.94 mg / m ² .
Similarly to the focusing example 1, CF1 was treated with water, a 1% by weight aqueous solution of homopolymer (P-1), and a 1% by weight aqueous solution of homopolymer (P-2). 3 sizing CF bundles (SPC-0, SPC-1 and SPC-2) were obtained. As a result of visual observation, fluffing frequently observed in SPC-0 did not occur in SAC-1, SPC-1, and SPC-2. Moreover, it turned out that SAC-1 and SPC-2 have softness with respect to SPC-1 which became hard, are excellent in touch, and are easy to process. Each photograph is shown in FIG.

<Production 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 used to further react with a carbon material, a thermoplastic resin, or a mixture thereof, which is a solid material. Thus, the following three types of carbon composite materials can be produced.
(1) Carbon composite material (carbon / copolymer / carbon) composed of carbon material and surface-modified carbon material
This type of composite material, like the production of surface-modified carbon materials, is a simultaneous heating method in which a carbon material and a surface-modified carbon material are contacted with each other in a liquid medium by heating, or a carbon material and a surface in a liquid medium. There is a post-heating method in which the reaction is performed by heating after contacting with the modified carbon material.
(2) Carbon composite material (resin / copolymer / carbon) composed of thermoplastic resin and surface-modified carbon material
This type of composite material can be manufactured 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 contact with the surface-modified carbon material in a molten state by a melt extruder or the like. This method is preferred because the resulting carbon composite can be formed directly.
(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 manufactured by dry blending a surface-modified carbon material, a carbon material, and a general-purpose resin and then reacting them by melt-kneading. In addition, the “carbon / co-polymer” obtained in (1) above can be used. It can also be produced by melting and kneading a polymer / carbon type carbon composite material with a general-purpose resin.

Carbon composite material production example 1 (composite example 1)
Disperse 20 g of dispersion 1 obtained in dispersion example 1 and 1 g of chopped carbon fiber CF2 cut to 5 mm into a 100 mL screw tube, close the lid, and use a lab shaker at room temperature for 60 minutes at a speed of 200 rpm. Vibrated. Then, CF2 after the treatment is taken out with a 50 μm mesh filtration device, heated at 80 ° C. for 2 hours, and further dried at 40 ° C. under vacuum for 2 hours to obtain a solid carbon composite material (CAC-1) did. In addition, the obtained CAC-1 was washed twice with ethanol using a lab shaker (200 rpm, 15 minutes / once), and the solid after the washing was dried under vacuum to obtain the ethanol of the carbon composite material CAC-1. Acquired cleaning products. The surface state of the untreated cut product CF2 and the surface state of the carbon composite material CAC-1 and its ethanol-cleaned product were observed with a scanning electron microscope (FE-SEM, JEOL JIS-6700F), and respective photographs are shown in FIG. .

Examples 2 and 3 for producing carbon composite materials (Composite Examples 2 and 3)
Surface-modified carbon material AC-1, CF2 and NMP obtained in Example 1 for producing surface-modified carbon material were weighed at a weight ratio of 1:10:89, and treated for 30 minutes at 25 ° C. with a bath-type ultrasonic device. . Thereafter, the mixture is heated at 150 ° C. for 0.5 hours, and the resulting black solid is separated by filtration, and washed twice with ethanol using a lab shaker (200 rpm, 15 minutes / once). The subsequent solid was dried under vacuum to obtain a solid carbon composite material (CAC-2). Washing with ethanol was performed in the same manner as in Composite Example 1 to obtain a CAC-2 washed product.
Moreover, the solid mixture after ultrasonication was not heated, but the solid was separated by filtration and heated at 180 ° C. for 0.2 hours to obtain a solid carbon composite material (CAC-3). In the same manner as above, ethanol washing was performed to obtain a CAC-3 washed product. The surface states of CAC-2, CAC-3 and their cleaned products were observed with a scanning electron microscope, and the photograph is shown in FIG.

Examples 4 and 5 (Composite Examples 4 and 5) for producing carbon composite materials
The surface-modified carbon material AC-1 and NMP were weighed at a weight ratio of 2:98, and treated for 30 minutes at 25 ° C. with a bath-type ultrasonic device. Thereafter, the mixed liquid is heated to 150 ° C., and a carbon material (CF1 3 m) cut to a length of 3 m is passed through a tank filled with the mixed liquid having a width of 300 mm at a speed of 0.5 mm / second, and the ethanol tank having the same width is passed. Was passed twice (2 mm / second), and the washed fibrous solid was dried to obtain a solid fibrous carbon composite material (CAC-4).
Further, without heating the mixed solution after the ultrasonic treatment, a carbon material (CF1 3 m) cut to 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 / second, and 200 ° C. Baked by heating for 0.1 hour, passed through an ethanol bath of the same width twice (2 mm / sec), dried the fibrous solid after washing, and solid fibrous carbon composite material (CAC-5) ).

Examples 6 to 9 for producing carbon composite materials (composite examples 6 to 9)
Using the surface-modified carbon material AC-2 obtained in Example 2 for producing the surface-modified carbon material and the surface-modified carbon material AC-3 obtained in Example 3 for producing the surface-modified carbon material, the predetermined conditions shown in Table 5 were used. Based on the conditions, Examples 6 to 9 were performed to obtain a solid carbon composite material (CAC-6 to 9).

Comparative examples 1 to 4 for producing carbon composite materials (composite comparative examples 1 to 4)
In accordance with the procedure of Example 4 for producing the carbon composite material, Comparative Example 1 was performed under the conditions shown in Table 5 to obtain a fibrous carbon composite material (CPC-1). Further, in accordance with the procedures of Examples 2 and 3 for producing the carbon composite material, Comparative Examples 2 to 4 were performed under the conditions shown in Table 5 to obtain solid carbon composite materials (CPC-2 to 4). CPC-4 is obtained by directly attaching CNT and CF without using any dispersion accelerator such as a copolymer or improving adhesiveness. Moreover, the ethanol washing | cleaning was performed similarly to the composite example 1, and the washing | cleaning goods of CPC-1-4 were acquired. The surface states of CPC-1, CPC-2 and their washed products were observed with a scanning electron microscope, and the photograph is shown in FIG.

  From the results of FIGS. 5 to 7, it is clear that the carbon composite material formed through the copolymer (A) of the present invention has the CNT firmly coated on the CF surface. In addition, 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 in the copolymer (A) has high reactivity, and the formed chemical bond is Strong, even if it comes into contact with carbon materials such as CNT and CF only at room temperature, it forms a strong chemical bond by heating, and even if it is washed, it removes only the amount attached to the surface. It was confirmed that the CNTs were uniformly fixed to each other. In addition, when a homopolymer of 2-oxazoline monomer (a) is used, CNTs are partially fixed on the CF surface, but there are many places and lumps that cannot be attached, and the CNT uniform adhesion film on the CF surface Could not get. Further, when the homopolymer of the low Tg vinyl monomer (b) is used, the CNT and the polymer slightly adhered to the CF surface before washing are completely removed by washing, and the original system (untreated CF2) Similarly, neither CNT adhesion nor adhesion was confirmed on the surface, and it was found that a composite of CF and CNT could not be obtained.

Examples 1 to 8 (resin composite examples 1 to 8) and comparative examples 1 to 6 (resin composite comparative examples 1 to 6) for producing a resin composite material
Using PP, PMP, PA and PMA as general-purpose resins, the surface-modified carbon material (copolymer / carbon) and carbon composite material (carbon / copolymer / carbon) of the present invention have the compositions shown in Table 6. Dry blended and melt-kneaded under the predetermined conditions shown in Table 6 using a batch-type twin-screw kneader (Laboplast Mill μ manufactured by Toyo Seiki Co., Ltd.), resin / surface modified carbon material, resin / carbon composite Resins and carbon composite materials 1 to 8 (hereinafter abbreviated as resin composite materials) composed of materials and resin / surface modified carbon material / carbon composite material were produced. Using the obtained resin composite material, a hot-press machine (miniTEST PRESS-10 manufactured by Toyo Seiki Co., Ltd.) was used to produce a 200 μm-thick film (molding temperature 235 ° C., pressure 5 MPa after pressurizing for 2 minutes) A press film was prepared by rapid cooling in 1 minute.) A dumbbell test piece having a length of 35 mm and a width of 2.5 mm was punched out from the obtained press film, and a tensile tester (universal test manufactured by Toyo Seiki Co., Ltd.) with 15 mm between chucks. The tensile test was performed at a speed of 10 mm / min. In each Example and Comparative Example, the average value of the tensile strength of five test pieces is taken and shown in Table 6.

  From the results of Table 6, the resin composite material formed through the copolymer (A) of the present invention was modified with a copolymer on the surface of CF or CNT (resin / surface modified carbon material, resin / carbon composite). Material), the adhesion to polyolefin general-purpose resins and their acid-modified resins was improved, and the mechanical strength of the resulting resin composite was improved. In addition, when the resin / surface-modified carbon material / carbon composite material was added to the general-purpose resin, it was confirmed that the mechanical strength of the resin composite material was further improved by the reinforcing effect of both CNT and CF. On the other hand, when a homopolymer of B-CNT or a low Tg vinyl monomer (b) that is not modified by the copolymer of the present invention is used, the resin cannot disperse and adhere to the carbon material. No improvement in strength was confirmed. In addition, in the homopolymer of 2-oxazoline monomer (a) and the polymer outside the range of the copolymer composition ratio specified in the present invention, the effect of improving dispersibility and adhesiveness due to their blending is low. The improvement in strength was extremely low. In particular, when nothing was present between CF and CNT, adhesion imparting and reinforcing effects were not shown at all.

Resin composite material production example 9 (resin composite example 9) and comparative example 7 (resin composite comparative example 7)
0.1 g of copolymer A-1 obtained in the synthesis example was dissolved in 99.9 g of water to prepare an aqueous solution of polymer A-1 having a concentration of 0.1% by weight. Similarly, an aqueous solution of the homopolymer P-1 of 2-oxazoline monomer (a) obtained in Synthesis Comparative Example 1 was prepared. Two bundles of CF1 cut to 10 cm were prepared, and the bundles of CF1 were put into the polymer solutions of A-1 and P-1, respectively, and impregnated for 5 minutes to perform sizing treatment. Thereafter, vacuum drying was performed at 100 ° C. for 1 hour to obtain sizing-treated fibers COPA-1 and COPP-1.
As a general-purpose resin, 5 g of PP was weighed, and a pressure of 5 MPa was applied with a hot press machine heated to 200 ° C. to produce a film having a thickness of about 0.5 mm. Using two PP press films, placed above and below the fibers COPA-1 and COPP-4, and held at 200 ° C. and a pressure of 5 MPa for 10 seconds with a hot press machine, resin impregnated composite materials COPA-1-PP and COPP -1-PP was obtained, and the resin impregnation into the CF bundle was visually observed.

  FIG. 8 shows photographs and enlarged photographs of the resin-impregnated composite materials COPA-1-PP and COPP-1-PP. Since the copolymer A-1 of the present invention has a low Tg, it has high affinity with PP resin and high adhesiveness, the resin uniformly penetrates into the fiber bundle, the resin adheres to the surface of the fiber, and the fiber is moderately dissolved. That is, a fiber bundle excellent in resin impregnation property was obtained. On the other hand, the homopolymer P-1 had a high Tg (108 ° C.) and the treated fiber was hard, so the affinity and adhesion with the PP resin were low, and the impregnation property was poor.

Photo for dispersibility evaluation (a) Optical microscope image, (b) Black and white image ¹ H-NMR chart of copolymer A-1 (A) Dispersion Example 2, (b) Dispersion Example 5, (c) Dispersion Comparison Example 1, (d) Dispersion Comparison Example 2, (e) Dispersion Comparative Example 3 Photograph after processing of focusing example and focusing comparison example (a) Focusing example 1 (SC-1), (b) Focusing comparison example 1 (PC-0), Focusing comparison example 2 (PC-1) SEM photograph of carbon composite material Example 1 (a) Surface photograph of untreated cut product CF2, (b) Surface photograph of carbon composite material CAC-1, (c) Surface photograph of carbon composite material CAC-1 washed product SEM photographs of carbon composite materials Examples 2 and 3 (a) Surface photograph before cleaning of carbon composite material CAC-2, (b) Surface photograph of carbon composite material CAC-2 cleaned product, (c) Carbon composite material CAC-3 Surface photograph before cleaning, (d) Surface photograph of carbon composite CAC-3 cleaned product SEM photographs of carbon composite material comparative examples 1 and 2 (a) Surface photograph before CPC-1 cleaning, (b) Surface photograph of CPC-1 cleaned article, (c) Surface photograph before CPC-2 cleaning, (d) Surface photograph of carbon composite material CPC-2 washed product SEM photograph of resin-impregnated composite material (a) Photograph of COPA-1-PP, (b) Enlarged photograph of COPA-1-PP, (c) Photograph of COPP-1-PP

  The copolymer of the present invention exhibits unique properties such as promoting dispersion of carbon materials into other types of materials, improving the surface adhesion of carbon materials, and improving the convergence of fibrous carbon materials. Dispersion accelerators, adhesion improvers, bundling agents, sizing agents, etc. do not require special dispersion and surface treatment techniques and equipment, and do not impair the original properties of carbon materials, and various carbon materials can be used in a simple manner. Hydrophilicity and adhesiveness can be imparted to the surface of the film. Carbon materials whose surfaces have been modified using the adhesion improver (surface-modified carbon materials) can be easily produced by industrial means, and are made unique by reacting with various solid materials using them. A suitable carbon composite material having performance can be provided. Various carbon composite materials obtained by the present invention are blended with general-purpose thermoplastic resins such as polyolefins and thermosetting resins such as epoxy and polyimide, while maintaining high mechanical properties of the composite resin, It can be expected to significantly improve characteristics, impact resistance and rigidity. In various industrial fields, various engineering plastics, especially bumpers, instrument panels, console boxes, roof sheets, panel covers, electrical components, etc. Related products such as interior / exterior parts, household appliances, furniture, miscellaneous goods, molded products of medical materials, food containers, food packaging, packaging materials such as general packaging, coating materials such as electric wires and cables, architecture / civil engineering, stationery / It is suitable for industrial materials such as office supplies, compatibilizers or adhesives for various polymer alloys.

Claims (6)

A co-polymer containing 2 to 95 mol% of 2-oxazoline monomer (a) and 2 to 95 mol% of vinyl monomer (b) having a glass transition temperature (Tg) of the homopolymer of −100 to 70 ° C. as structural units. A carbon material adhesion improver using a polymer (A), wherein the copolymer (A) has a Tg of -80 to 75 ° C. A surface-modified carbon material that is surface-modified with the adhesion improver according to claim 1 . The surface-modified carbon material according to claim 2 , wherein the surface contains 0.1 to 100 mg / m ^{2 of} an adhesion improver. A co-polymer containing 2 to 95 mol% of 2-oxazoline monomer (a) and 2 to 95 mol% of vinyl monomer (b) having a glass transition temperature (Tg) of the homopolymer of −100 to 70 ° C. as structural units. A method for producing a surface-modified carbon material, characterized by using an aqueous dispersion obtained by dispersing the polymer (A) in water, impregnating the carbon material in the aqueous dispersion and then heating. A carbon composite material consisting of a surface-modified carbon material and a solid material according to claim 2 or 3, and a solid material is a carbon material, the solid material a carboxyl group, a phenolic hydroxyl group, an acid anhydride functional group , Having one or more functional groups selected from the group consisting of epoxy groups, thiol groups, amine groups and amide groups, and chemical bonds formed by reaction with oxazoline groups of these functional groups between surface-modified carbon materials and solid materials Carbon composite material characterized by being in between. A carbon composite material comprising the surface-modified carbon material according to claim 2 or 3 and a solid material , wherein the solid material is a carbon material and a thermoplastic resin, and the solid material includes a carboxyl group, a phenolic hydroxyl group, an acid Surface-modified carbon materials that have one or more functional groups selected from the group consisting of anhydride functional groups, epoxy groups, thiol groups, amine groups and amide groups, and react with oxazoline groups of these functional groups A carbon composite material that exists between a solid material and a solid material.