JP6511987B2 - Carbon fiber sizing agent and carbon fiber - Google Patents

Description

  The present invention relates to a carbon fiber sizing agent that can be used for carbon fiber focusing.

  As automobile members, aircraft members and the like which are required to have high strength and excellent durability, for example, fiber reinforced plastics containing a matrix resin such as epoxy resin and vinyl ester resin and carbon fibers are used.

  As a carbon fiber used for the fiber reinforced plastic, usually from the viewpoint of imparting high strength, a fiber material which is gathered to several thousands to several tens of thousands by a fiber sizing agent is often used.

As the fiber sizing agent, for example, sizing agents containing an epoxy resin and a water-soluble urethane resin are known (see, for example, Patent Documents 1 to 3). However, in these sizing agents, a reaction between the epoxy resin and the urethane resin having a carboxyl group may occur, and the bundling ability, the openability, and the mechanical strength of the molded product may be reduced.

  Also, a fiber sizing agent is known in which an epoxy resin is dispersed in an aqueous medium by a urethane resin having an alkoxypolyoxyethylene structure and an epoxy group (see, for example, Patent Document 4).

  However, in carbon fiber reinforced plastic (CFRP) using this fiber sizing agent, when thermosetting resin is used as the matrix resin, mechanical strength is improved, but when thermoplastic resin is used. In some cases, the focusing ability and mechanical strength may be insufficient.

Japanese Patent Application Laid-Open No. 62-110984 JP-A-1-162876 JP-A-9-250087 JP, 2013-249562, A

  The problem to be solved by the present invention is that it can be used for the production of a fiber bundle capable of imparting excellent strength to a molded product when using either a thermoplastic resin or a thermosetting resin as a matrix resin. It is an object of the present invention to provide a carbon fiber sizing agent which is excellent in carbon fiber bundling ability and scratch resistance.

  As a result of investigations to solve the above problems, the present inventors have studied urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure, urethane resin having a sulfonate group having a carboxyl group concentration of 0.05 mmol / g or less, and By using a carbon fiber sizing agent containing an aqueous medium, it has been found that the above problems can be solved, and the present invention has been completed.

  That is, the present invention is a carbon fiber sizing agent containing a urethane-modified epoxy resin (A) having an alkoxy polyoxyalkylene structure, a urethane resin (B) having a sulfonate group, and an aqueous medium, The present invention relates to a carbon fiber sizing agent characterized in that the concentration of carboxyl groups in B) is 0.05 mmol / g or less.

  The carbon fiber sizing agent of the present invention has good storage stability of epoxy groups, is excellent in carbon fiber focusing property, and can be used for producing a fiber bundle capable of imparting excellent strength to a molded article, It can be suitably used as a carbon fiber sizing agent (sizing agent).

  The carbon fiber sizing agent of the present invention is a carbon fiber sizing agent containing a urethane-modified epoxy resin (A) having an alkoxypolyoxyalkylene structure, a urethane resin (B) having a sulfonate group, and an aqueous medium, The concentration of the carboxyl group in the urethane resin (B) is 0.05 mmol / g or less.

  The urethane modified epoxy resin (A) which has the said alkoxy polyoxyalkylene structure is demonstrated. The urethane-modified epoxy resin (A) has an alkoxypolyoxyalkylene structure, but the alkoxypolyoxyalkylene structure is a structure in which one end of a polyoxyalkylene chain is blocked by an alkoxy group.

  Examples of the polyoxyalkylene chain include, for example, a polyoxyethylene chain, a polyoxypropylene chain, a polyoxybutylene chain and the like, and also include those in which these are arranged in block or random form.

  As an alkoxy group which blocks the end of the polyoxyalkylene chain, for example, a methoxy group, an ethoxy group, a propoxy group, a butoxy group and the like can be mentioned.

  It is preferable that the alkoxy polyoxyalkylene structure has 40 mass% or more of a structure of an oxyethylene unit in the structure, since water dispersibility is further improved.

  In addition, the alkoxy polyoxyalkylene structure preferably has a number average molecular weight of 300 to 7,000 because water dispersibility is further improved.

  The alkoxypolyoxyalkylene structure is preferably present in the range of 3 to 60% by mass, and preferably in the range of 10 to 55% by mass, in the epoxy resin (A), since the water dispersibility is further improved. It is more preferable to do.

  The urethane-modified epoxy resin (A) is, for example, a compound (a1) having an epoxy group and a hydroxyl group in the absence of a solvent or in the presence of an organic solvent, polyisocyanate (a2), polyoxyalkylene monoalkyl ether (a3) If necessary, a polyol (a4) other than the compound (a1) and a chain extender (a5) can be produced by reacting them by a conventionally known method. Specifically, in consideration of safety, it is preferable to react at a reaction temperature of 50 to 120 ° C. for 1 to 15 hours.

  Examples of the compound (a1) having an epoxy group and a hydroxyl group include a bisphenol A epoxy resin having a hydroxyl group, a bisphenol epoxy resin such as bisphenol A and bisphenol F, a phenol novolac epoxy resin, and an ethylphenol novolac epoxy Cresol novolac epoxy resin such as resin, butylphenol novolac epoxy resin, octylphenol novolac epoxy resin, ortho cresol novolac epoxy resin, resorcinol novolac epoxy resin, bisphenol A novolac epoxy resin, bisphenol F novolac epoxy resin, bisphenol AD Some of the epoxy groups possessed by novolac epoxy resin, bisphenol S novolac epoxy resin, etc. Ring opening by reacting with an equal, can be used after forming a hydroxyl group.

  As the compound (a1), since the mechanical strength of the resulting molded article is further improved, a phenol novolac epoxy resin having a hydroxyl group, a cresol novolac epoxy resin having a hydroxyl group, or a bisphenol A epoxy resin having a hydroxyl group It is preferred to use.

  As said compound (a1), it is preferable to use what is an epoxy equivalent of 100-2,000 g / equivalent, and it is more preferable to use what is 100-500 g / equivalent.

  The hydroxyl group possessed by the compound (a1) can improve the fiber bundling property and the mechanical strength of the resulting molded article, so that it is 5-150 relative to the total amount of epoxy groups possessed by the urethane-modified epoxy resin (A). It is preferably in the range of mol%, more preferably in the range of 5 to 130 mol%, and still more preferably in the range of 5 to 120 mol%.

  The reaction between a part of the epoxy group of the epoxy resin and the carboxylic acid is carried out by mixing the epoxy resin and the carboxylic acid in a reaction vessel and stirring at 40 to 90 ° C. for 5 to 15 hours. Can.

  Examples of the polyisocyanate (a2) include 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, Aromatic polyisocyanates such as tetramethyl xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate and cyclohexane diisocyanate, polyisocyanates having an aliphatic cyclic structure such as isophorone diisocyanate and dicyclohexylmethane diisocyanate, and their nulates Body or trim And the like can be used adduct of trimethylolpropane and the like. Among these, it is preferable to use diisocyanate.

  The polyoxyalkylene monoalkyl ether (a3) is represented by the following general formula (1).

（式中、Ｒ^１はアルキル基を表し、Ｒ^２はアルキレン基を表し、ｎは１以上の整数を表す。）

(Wherein, R ¹ represents an alkyl group, R ² represents an alkylene group, and n represents an integer of 1 or more).

The polyoxyalkylene monoalkyl ether (a3) is preferably ^{one in} which R ¹ in the general formula (1) is a methyl group, an ethyl group, a propyl group or a butyl group because the storage stability is further improved. And methyl groups are more preferable.

Further, R ² in the general formula (1) is preferably an ethylene group or a propylene group, and more preferably an ethylene group, because the storage stability and the fiber bundling property are further improved.

  In the above general formula (1), n is preferably an integer of 5 to 150, and more preferably an integer of 5 to 100, because storage stability, fiber convergence, and the strength of the resulting molded article are further improved.

  Further, as the polyoxyalkylene monoalkyl ether (a3), those having a hydroxyl value in the range of 10 to 200 are preferable, and those having the range of 15 to 200 are more preferable, because the storage stability is further improved.

  As the polyoxyalkylene monoalkyl ether (a3), it is more preferable to use polyoxyethylene monoalkyl ether because storage stability and fiber bundling properties are further improved, and polyoxyethylene monomethyl ether is used. Is particularly preferred.

  Examples of the polyol (a4) include polyether polyols, polycarbonate polyols, polyester polyols, ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1, 5-Pentanediol, 1,6-Hexanediol, 1,4-Cyclohexanedimethanol, neopentyl glycol, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, acrylic polyol having acrylic group with hydroxyl group introduced, intramolecular And polybutadienepolyol which is a copolymer of butadiene having a hydroxyl group, hydrogenated polybutadienepolyol, and partially saponified ethylene-vinyl acetate copolymer.

  As said polyether polyol, what carried out addition polymerization of the alkylene oxide can be used, for example using 1 type, or 2 or more types of a compound which has an active hydrogen atom 2 or more as an initiator.

  Moreover, as said polycarbonate polyol, what is obtained by making a carbonic acid ester and a polyol react, for example, and a thing obtained by making a phosgene, bisphenol A, etc. react can be used.

  Further, as the polyester polyol, for example, a polyester polyol obtained by subjecting a low molecular weight polyol and a polycarboxylic acid to an esterification reaction, or a ring-opening polymerization reaction of a cyclic ester compound such as ε-caprolactone or γ-butyrolactone The resulting polyester, copolyesters of these, etc. can be used.

  As said polyether polyol, said polycarbonate polyol, and said aliphatic polyester polyol, it is preferable to use a thing of a number average molecular weight 300-4,000, and it is more preferable to use a thing of 500-2,000.

  As the chain extender (a5), polyamines and other compounds having an active hydrogen atom can be used.

  Examples of the polyamine include ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophorone diamine, 4,4'-dicyclohexylmethanediamine, 3,3'- Diamines such as dimethyl-4,4'-dicyclohexylmethanediamine and 1,4-cyclohexanediamine; N-hydroxymethylaminoethylamine, N-hydroxyethylaminoethylamine, N-hydroxypropylaminopropylamine, N-ethylaminoethylamine, N-methylaminopropylamine; diethylenetriamine, dipropylenetriamine, triethylenetetramine; hydrazine, N, N'-dimethylhydrazine, 1,6-hexamethylene bishydrazine; succinic acid Azide, adipic acid dihydrazide, glutaric acid dihydrazide, sebacic acid dihydrazide, isophthalic acid dihydrazide; β-semicarbazide propionic acid hydrazide, 3-semicarbazide propyl carbazate, semicarbazide 3-semicarbazide methyl 3,5,5-trimethylcyclohexane It can be used.

  Examples of other compounds having active hydrogen include glycol compounds such as triethylene glycol, 1,3-propanediol, sucrose, methylene glycol and sorbitol; bisphenol A, 4,4′-dihydroxydiphenyl, 4,4′- Dihydroxy diphenyl ether, 4,4'-dihydroxy diphenyl sulfone, hydrogenated bisphenol A, phenolic compounds such as hydroquinone, water and the like can be used.

  The chain extender (a5) is preferably used, for example, in a range such that the equivalent ratio of the amino group of the polyamine to the excess isocyanate group is 1.9 or less (equivalent ratio), and 0.3 to 1 It is more preferable to use in the range of .0 (equivalent ratio).

  The urethanation reaction can be carried out without a catalyst, but known catalysts such as stannous octoate, dibutyltin dilaurate, dibutyltin dimaleate, dibutyltin diphthalate, dibutyltin dimethoxide, dibutyltin diacetyl acetate, dibutyl A tin compound such as tin diversatate, a titanate compound such as tetrabutyl titanate, tetraisopropyl titanate, triethanolamine titanate, or the like, or a tertiary amine compound, a quaternary ammonium salt, or the like may be used.

  The convergence is improved that the epoxy group contained in the urethane-modified epoxy resin (A) is present in the range where the epoxy equivalent of the urethane-modified epoxy resin (A) is 250 to 2,000 g / equivalent. It is preferable because molded articles of higher strength can be obtained.

  The urethane resin (B) having the sulfonate group is described. Although the said urethane resin (B) has a sulfonate group, since the stability at the time of water dispersion is improved more, the density | concentration of the sulfonate group in the said urethane resin (B) is 0.02-1 mmol / g Is preferable, and the range of 0.05 to 0.7 mmol / g is more preferable.

  Moreover, although the concentration of the carboxyl group in the urethane resin (B) is 0.05 mmol / g or less, it is preferably 0.02 mmol / g or less because the storage stability of the epoxy group is further improved. It is more preferable that it is 0.01 mmol / g or less.

  As the urethane resin (B), those having a weight average molecular weight in the range of 8,000 to 300,000 are preferable because mechanical strength and storage stability of the resulting molded article are further improved, and 10,000 More preferably, it is in the range of-200,000.

  The urethane resin (B) preferably has a glass transition temperature in the range of -80 to 60 ° C, and in the range of -80 to 10 ° C, since the mechanical strength of the resulting molded article is further improved. Is more preferred.

  The urethane resin (B) may be one having a sulfonate group, and for example, a polyol (b1) having a sulfonate group and a polyisocyanate (b2) in the absence of a solvent or in the presence of an organic solvent If necessary, it can be produced by reacting a chain extender (b3) with a polyol (b4) other than the polyol (b1) by a conventionally known method. Specifically, in consideration of safety, it is preferable to react at a reaction temperature of 50 to 120 ° C. for 1 to 15 hours.

  As the polyol (b1) having a sulfonate group, for example, a polyol in which a sulfonate group is introduced to a polyol described as a polyol (a4) usable for producing a urethane-modified epoxy resin (A) can be used. However, among these, the polyester polyol (b1-1) having a sulfonate group is preferable because the heat decomposition resistance of the urethane resin (B) is improved.

  The sulfonic acid group of the polyester polyol (b1-1) is, for example, a polyol having a sulfonic acid group, a polycarboxylic acid having a sulfonic acid group, and a compound having a sulfonic acid group such as an ester thereof. Can be introduced into the polyester polyol (b1-1).

  The polyol having a sulfonate group used as a raw material of the polyester polyol (b1-1) can be obtained, for example, by sulfonation of a polyol having an unsaturated group such as 2-butene-1,4-diol. Can be used.

  Examples of other polyols used as a raw material of the polyester polyol (b1-1) include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2-methyl- 1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butyl Aliphatic diols such as propanediol, diethylene glycol, triethylene glycol and dipropylene glycol; diols having an aliphatic cyclic structure such as 1,4-cyclohexanedimethanol; and glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like Has 3 or more hydroxyl groups It is possible to use polyols, and the like. These polyols can be used alone or in combination of two or more.

  Examples of polycarboxylic acid having a sulfonate group used as a raw material of the polyester polyol (b1-1) and esterified products thereof include 4-sulfoisophthalic acid, 5-sulfoisophthalic acid, sulfoterephthalic acid, and 4-sulfo. Naphthalene-2,7-dicarboxylic acid and metal salts such as esterified products thereof can be mentioned. Among these, it is preferable to use an esterified product of 5-sodium sulfoisophthalic acid, since dimethylpolysulfone is used, because the reaction efficiency in producing the polyester polyol (b1-1) is improved. Is more preferred.

  Examples of other polycarboxylic acids used as a raw material of the polyester polyol (b1-1) include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid and biphenyldicarboxylic acid; oxalic acid Succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, hydrogenated dimer acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic acid, citraconic acid, citraconic acid, dimer Saturated or unsaturated aliphatic dicarboxylic acids such as acids; 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5-norbornene dicarboxylic acid and its anhydride, tetrahydrofuran Aliphatic rings such as phthalic acid and its anhydrides And the like can be used dicarboxylic acids having the structure. Among these, it is preferable to use an aromatic dicarboxylic acid (anhydride) from the viewpoint of further improving heat resistance, and it is more preferable to use terephthalic acid or isophthalic acid.

  Moreover, as the polycarboxylic acid, in addition to those described above, trimellitic acid, pyromellitic acid, benzophenonetetracarboxylic acid, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic acid anhydride, trimesic acid, ethylene glycol bis It is also possible to use polycarboxylic acids having three or more carboxyl groups such as (anhydrotrimellitate), glycerol tris (anhydrotrimellitate), 1,2,3,4-butanetetracarboxylic acid and the like. These polycarboxylic acids can be used alone or in combination of two or more.

  Moreover, as a raw material of said polyester polyol (b1-1), cyclic ester compounds, such as (epsilon) -caprolactone and (gamma) -butyrolactone, can also be used. These cyclic ester compounds can be used alone or in combination of two or more. Among these, it is preferable to use ε-caprolactone because the bundling ability and the adhesion to the matrix resin are further improved.

  The polyester polyol (b1-1) can be produced by an esterification reaction of the polyol and the polycarboxylic acid in the absence of a solvent or in the presence of an organic solvent by a conventionally known method. In addition, if necessary, a compound in which a cyclic ester compound is ring-opened can be subjected to an esterification reaction.

  Specifically, the esterification reaction is carried out by heating the polyol and the polycarboxylic acid to 180 to 300 ° C. in the presence or absence of a catalyst in an inert gas atmosphere to carry out esterification or transesterification It can be carried out by a method of polycondensation.

  In addition, the compound having a sulfonate group used when producing the polyester polyol (b1-1) is 3 to 30% by mass of the total of the polyol and the polycarboxylic acid because the storage stability is further improved. It is preferable to use in the range of

  As for the polyester polyol (b1-1), the hydroxyl value of the polyester polyol (b1-1) is preferably in the range of 50 to 500, since the bundling ability and the mechanical strength are further improved.

  As said polyisocyanate (b2), what was described as polyisocyanate (a2) which can be used for manufacture of a urethane modified epoxy resin (A) can be used.

  As said chain extender (b3), what was described as a chain extender (a5) which can be used for manufacture of urethane modified epoxy resin (A) can be used.

  As said polyol (b4), the polyol described as a polyol (a4) which can be used for manufacture of a urethane modified epoxy resin (A) can be used.

  Moreover, what was described as a catalyst which can be used for manufacture of the said urethane modified epoxy resin (A) can be used for manufacture of the said urethane resin (B).

Examples of the aqueous medium include water, water-miscible organic solvents, and mixtures thereof. Examples of the organic solvent miscible with water include methanol, ethanol, n-
And alcohol compounds such as isopropanol; ketone compounds such as acetone and methyl ethyl ketone; polyalkylene glycol compounds such as ethylene glycol, diethylene glycol and propylene glycol; alkyl ether compounds of polyalkylene glycols; lactam compounds such as N-methyl-2-pyrrolidone and the like Can be mentioned. In the present invention, only water may be used, or a mixture of water and an organic solvent miscible with water may be used, or only an organic solvent miscible with water may be used. From the viewpoint of safety and environmental load, water alone or a mixture of water and an organic solvent miscible with water is preferred, and water alone is particularly preferred.

  The carbon fiber sizing agent of the present invention may be produced, for example, by dissolving or dispersing the urethane-modified epoxy resin (A) in an aqueous medium, and dissolving or dispersing the urethane resin (B) in an aqueous medium. And a method of mixing the obtained mixture and an aqueous medium after mixing the urethane-modified epoxy resin (A) and the urethane resin (B).

  The mass ratio of the urethane-modified epoxy resin (A) in the solid content of the carbon fiber sizing agent of the present invention is preferably in the range of 20 to 90 mass%, since the fiber openability and mechanical strength are further improved. The range of 80% by mass is more preferable.

  The mass ratio of the urethane resin (B) in the solid content of the carbon fiber sizing agent of the present invention is preferably in the range of 10 to 80% by mass, and 20 to 70% by mass because the bundling ability and mechanical strength are further improved. The range is more preferred.

  The mass ratio of the aqueous medium in the carbon fiber sizing agent of the present invention is preferably in the range of 20 to 98 mass%, more preferably in the range of 30 to 90 mass%, because storage stability and coating workability are further improved. More preferable.

  The mass ratio of the solid content in the carbon fiber sizing agent of the present invention is preferably in the range of 2 to 80% by mass, and more preferably in the range of 10 to 70% by mass since storage stability and coating workability are further improved. preferable.

  In addition, the carbon fiber sizing agent of the present invention may be, if necessary, a silane coupling agent, a curing catalyst, a lubricant, a filler, a thixo agent, a tackifier, a wax, a heat stabilizer, a light stabilizer, a fluorescent whitening agent Agents, additives such as foaming agents, pH adjusters, leveling agents, antigelling agents, dispersion stabilizers, antioxidants, radical scavengers, heat resistance imparting agents, inorganic fillers, organic fillers, plasticizers, reinforcements Agents, catalysts, antibacterial agents, fungicides, rust inhibitors, thermoplastic resins, thermosetting resins, pigments, dyes, conductivity imparting agents, antistatic agents, moisture permeability improvers, water repellents, oil repellents, hollow Foam, crystal water containing compound, flame retardant, water absorbing agent, hygroscopic agent, deodorant, foam stabilizer, antifoam, antifungal agent, preservative, algaecide, pigment dispersant, antiblocking agent, hydrolysis An inhibitor can be used in combination.

  The carbon fiber sizing agent of the present invention is, for example, an emulsion of vinyl acetate type, ethylene vinyl acetate type, acrylic type, epoxy type, urethane type, polyester type, polyamide type, etc .; styrene-butadiene type, acrylonitrile-butadiene type, It can also be used in combination with an acrylic-butadiene based latex, or a water-soluble resin such as polyvinyl alcohol or cellulose.

  As the carbon fiber sizing agent of the present invention, an emulsifier or the like may be used as long as the effects of the present invention are not impaired. The amount of the emulsifier used is preferably 10 parts by mass or less with respect to 100 parts by mass in total of the urethane-modified epoxy resin (A) and the urethane resin (B).

  The carbon fiber sizing agent of the present invention can be used for fiber focusing and surface treatment for the purpose of preventing carbon fiber breakage and fuzzing.

  Moreover, as a carbon fiber which can be processed using the carbon fiber sizing agent of this invention, carbon fibers, such as a polyacrylonitrile type and a pitch type, are mentioned, for example. Among these, it is preferable to use a polyacrylonitrile-based carbon fiber because the molded article can be given more excellent strength.

  Moreover, as said carbon fiber, it is preferable to use the thing which has a single yarn diameter of 0.5-20 micrometers from a viewpoint of providing the further outstanding strength, and it is more preferable to use the thing of 2-15 micrometers. .

  As the carbon fiber, for example, those obtained by twisting, spinning, spinning, non-woven processing can be used. Further, as the carbon fibers, filaments, yarns, rovings, strands, chopped strands, felts, needle punches, cloths, roving cloths, milled fibers, etc. can be used.

  As a method of focusing the carbon fibers with the carbon fiber sizing agent of the present invention and forming a film on the surface of a carbon fiber bundle, for example, a carbon fiber sizing agent is applied by a kiss coater method, roller method, dipping method, spray The carbon fiber bundling agent may be uniformly applied to the fiber surface by a method, brush, or other known method. When the carbon fiber sizing agent contains an aqueous medium or an organic solvent as a solvent, it is preferable to heat and dry after the application using a heating roller, a hot air, a hot plate or the like.

  The amount of the film formed on the surface of the carbon fiber is preferably 0.1 to 5% by mass, preferably 0.3 to 1.5% by mass, with respect to the total mass of the fiber bundle subjected to the focusing and surface treatment. % Is more preferable.

  Using the carbon fiber which has been subjected to the focusing and surface treatment obtained by the above method, in combination with the matrix resin (C) described later, etc., as a molding material for producing a high-strength molded article Can.

  In particular, when the carbon fiber surface-treated with the carbon fiber sizing agent of the present invention is used in combination with the matrix resin (C) to form a molded article etc., the interface between the carbon fiber and the matrix resin (C) The adhesion of the molded article can be remarkably improved, so that the strength of the molded article can be improved.

  As said matrix resin (C), a thermosetting resin (C1) or a thermoplastic resin (C2) can be used, for example. A phenol resin, a polyimide resin, a bismaleimide resin, an unsaturated polyester resin, an epoxy resin, a vinyl ester resin etc. can be used as said thermosetting resin (C1). The thermoplastic resin (C2) is, for example, a saturated polyester resin such as polyethylene terephthalate or polybutylene terephthalate, polypropylene, polystyrene, polycarbonate, polyphenylene sulfide, polyphenylene oxide, polyamide resin such as 6-nylon or 6,6-nylon, Acrylonitrile-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, polyacetals, polyetherimides, polyetheretherketones and the like can be used.

  Fibers collected by using the carbon fiber sizing agent of the present invention may be epoxy resin, unsaturated polyester resin, polyamide resin such as 6-nylon or 6,6-nylon, polyphenylene sulfide, polybutylene terephthalate, polycarbonate, poly It is more preferable to obtain a high-strength molded article by using it in combination with an ether ether ketone matrix resin.

  Examples of the molding material containing the surface-treated carbon fiber, the matrix resin (C), and, if necessary, a polymerizable monomer and the like include a prepreg and a sheet molding compound (SMC). .

  In the prepreg, for example, the matrix resin (C) is applied onto a release paper, the surface-treated carbon fiber is placed on the coated surface, and pressure impregnation is performed using a roller or the like as necessary. It can be manufactured by

  When producing the prepreg, it is preferable to use, as the matrix resin (C), an epoxy resin such as a bisphenol A epoxy resin, a glycidyl amine epoxy resin such as tetraglycidyl aminodiphenylmethane, or a novolac epoxy resin. .

  In addition, the sheet molding compound sufficiently impregnates, for example, a mixture of the matrix resin (C) and a polymerizable unsaturated monomer such as styrene into the surface-treated carbon fiber to form a sheet. It can manufacture by processing etc. When manufacturing the said sheet molding compound, it is preferable to use unsaturated polyester resin and vinyl ester resin as said matrix resin (C).

  Curing of the molding material proceeds by radical polymerization, for example, by heating or light irradiation under pressure or normal pressure. In such a case, known heat curing agents, light curing agents and the like can be used in combination.

  Further, as the molding material, for example, one obtained by kneading the thermoplastic resin (C2) and the carbon fiber subjected to the surface treatment under heating and the like can be mentioned. Such a molding material can be used for secondary processing by, for example, an injection molding method.

  Moreover, the prepreg by the said thermoplastic resin (C2) can be manufactured by, for example, mounting the carbon fiber in which the surface treatment was given in a sheet form, and impregnating the fuse | melted said thermoplastic resin (C2) .

The prepreg based on the thermoplastic resin (C2) can be used, for example, for secondary processing by laminating one or more sheets and then heating and molding under pressure or normal pressure.

  Molded articles obtained using the molding materials have high strength, and can be used, for example, as automobile members, aircraft members, housing members, industrial members, and the like.

  Hereinafter, the present invention will be more specifically described by way of examples. The concentration of the sulfonate group and the concentration of the carboxyl group are determined by calculation from the amounts of the raw materials charged. The acid value is measured in accordance with JIS K 0070-1992, and the hydroxyl value is measured in accordance with JIS K 1557-1.

  The glass transition temperature was measured by a method according to JIS K 7121 using a differential scanning calorimeter “DSC Q-100” (manufactured by TA Instrument). The sample of which the solvent was completely removed by vacuum suction was measured for the change in heat quantity in the range of -100 ° C to + 200 ° C at a temperature rise rate of 20 ° C / min. A point at which a straight line at a distance intersects with a curve of a step change portion of the glass transition is taken as a glass transition temperature.

The weight average molecular weight (Mw) was measured under the following measurement conditions.
[GPC measurement conditions]
Measuring device: High-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were used in series connection.
"TSKgel G5000" (7.8 mm ID × 30 cm) × 1 "TSK gel G 4000" (7.8 mm ID × 30 cm) × 1 "TSK gel G 3000" (7.8 mm ID × 30 cm) × 1 This "TSKgel G2000" (7.8 mm ID × 30 cm) × 1 detector: RI (differential refractometer)
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 4 mg / mL)
Standard sample: A calibration curve was prepared using the following monodispersed polystyrene.

(Monodispersed polystyrene)
Tosoh Corporation "TSKgel standard polystyrene A-500"
Tosoh Corporation "TSKgel standard polystyrene A-1000"
Tosoh Corporation "TSKgel standard polystyrene A-2500"
Tosoh Corporation "TSKgel standard polystyrene A-5000"
Tosoh Corporation "TSKgel standard polystyrene F-1"
Tosoh Corporation "TSKgel standard polystyrene F-2"
Tosoh Corporation "TSKgel standard polystyrene F-4"
Tosoh Corporation "TSKgel standard polystyrene F-10"
Tosoh Corporation "TSKgel standard polystyrene F-20"
Tosoh Corporation "TSKgel standard polystyrene F-40"
Tosoh Corporation "TSKgel standard polystyrene F-80"
Tosoh Corporation "TSKgel standard polystyrene F-128"
Tosoh Corporation "TSKgel standard polystyrene F-288"
Tosoh Corporation "TSKgel standard polystyrene F-550"

Production Example 1: Synthesis of Urethane-Modified Epoxy Resin (A-1)
10 parts by mass of polyethylene glycol (hydroxyl value: 187) and 100 parts by mass of methyl ethyl ketone are added to a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, and a dropping device, and sufficiently stirred and dissolved at 40 ° C. At 40 ° C., 30 parts by mass of tolylene diisocyanate was added and allowed to react at 60 to 65 ° C. for 4 hours. Then, add 80 parts by mass of bisphenol A type epoxy resin ("Epiclon 1050" manufactured by DIC Corporation, epoxy equivalent: 477 g / equivalent), and 70 parts by mass of polyethylene glycol monomethyl ether (hydroxyl value: 102). By reacting for 4 hours, a urethane-modified epoxy resin (A-1) having a methoxypolyoxyethylene structure and an epoxy group was obtained. In addition, the weight average molecular weight of the urethane modified epoxy resin (A-1) was 10,000. Next, 19 parts by mass of polyoxyalkylene tridecyl ether ("Nugen XL-400" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was added and sufficiently stirred. Then, 736 parts by mass of ion exchange water was dropped over 30 minutes, and the mixture was further stirred and mixed for 15 minutes. The aqueous dispersion was concentrated by distillation under reduced pressure to obtain an aqueous dispersion of urethane-modified epoxy resin (A-1) having a nonvolatile content of 30% by mass.

Production Example 2: Synthesis of Urethane-Modified Epoxy Resin (A-2)
A four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, and a dropping device, polyoxyethylene polyoxypropylene monobutyl ether ("NOILUB 50MB-26" manufactured by NOF Corporation, ethylene oxide added mole number: 17, 80 parts by mass of propylene oxide added mole number: 17, hydroxyl value: 29), 80 parts by mass of bisphenol A type epoxy resin ("Epiclon 1050" manufactured by DIC Corporation, epoxy equivalent: 477 g / equivalent), and 100 parts by mass of methyl ethyl ketone In addition, the mixture was sufficiently dissolved by stirring at 40 ° C. Then, 20 parts by mass of tolylene diisocyanate is added at 40 ° C., and the reaction is carried out at 60 to 65 ° C. for 6 hours to obtain a urethane-modified epoxy resin (A-2) having a butoxypolyoxyethylene polyoxypropylene structure and an epoxy group. I got In addition, the weight average molecular weight of the urethane modified epoxy resin (A-2) was 15,000.
Subsequently, 18 parts by mass of polyoxyethylene distyrenated phenyl ether ("Emulgen A-500" manufactured by Kao Corp.) was added and sufficiently stirred. Next, 692 parts by mass of ion exchanged water was dropped over 30 minutes, and the mixture was further stirred and mixed for 15 minutes. The aqueous dispersion was concentrated by distillation under reduced pressure to obtain an aqueous dispersion of urethane-modified epoxy resin (A-2) having a nonvolatile content of 30% by mass.

Production Example 3: Synthesis of Polyester Polyol (b-1)
While nitrogen gas is introduced into a reaction vessel equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, 1480 parts by mass of dimethyl 5-sodium sulfoisophthalate and 1240 parts by mass of 1,6-hexanediol, and dibutyl tin oxide 0. Charge 5 parts by mass, perform transesterification until the acid value becomes 1 mg KOH / g or less at a temperature in the reaction vessel of 180 to 190 ° C. so that the tower top temperature is 60 to 70 ° C., and then 2 at 210 ° C. By reacting for time, an esterification reaction product having a hydroxyl value of 240 mg KOH / g and an acid value of 0.3 mg KOH / g was obtained. Furthermore, 2280 parts by mass of ε-caprolactone is added to the esterification reaction product, and ring opening polymerization reaction is carried out at 180 ° C. for 3 hours, whereby a hydroxyl value of 120 mg KOH / g, an acid value of 0.3 mg KOH / g, and a concentration of sulfonate group of 1.080 mmol / G polyester polyol (b-1) was obtained.

Production Example 4 Synthesis of Urethane Resin Having Sulfonic Acid Base (B-1)
30 parts by mass of polyester polyol (b-1) and 60 parts by mass of methyl ethyl ketone were added to a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, and a dropping device, and sufficiently stirred and dissolved. Next, 34 parts of isophorone diisocyanate and 4 parts by mass of hexamethylene diisocyanate were added and reacted at 80 ° C. for 3 hours. Next, 95 parts by mass of methyl ethyl ketone is added and cooled to 60 ° C., and then 5 parts by mass of 1,4-butylene glycol, polybutylene adipate which is a polyester composed of 1,4-butylene glycol and adipic acid (hydroxyl value 37 mg KOH / g, 160 parts by mass of acid value 0.3 mg KOH / g) were added and reaction was carried out at 80 ° C. Then, after confirming that the isocyanate content has become 0.79% or less, cool to 40 ° C., add 280 parts by mass of water, sufficiently stir and mix, and then 29.7 parts by mass of 10% piperazine aqueous solution (residual 95 equivalent% as an amine group) was added with respect to the isocyanate group, and it emulsified-dispersed. The obtained emulsion was desolventized to obtain an aqueous dispersion of a urethane resin (B-1) having a sulfonate group having a nonvolatile content of 50% by mass. The concentration of the sulfonate group in the urethane resin (B-1) having a sulfonate group is 0.137 mmol / g, the concentration of the carboxyl group is 0.004 mmol / g, and the weight average molecular weight is 80,000, glass The transition temperature was -45 ° C.

Production Example 5 Synthesis of Urethane Resin (RB-1)
In a 4-neck flask equipped with a thermometer, a stirrer, a reflux condenser, and a dropping device, 77 parts by mass of glycol (hydroxyl value 325 mg KOH / g) obtained by adding 2 moles of propylene oxide to bisphenol A, and 1,4-butylene glycol Add 221 parts by mass of polybutylene adipate (hydroxyl value 112 mg KOH / g, acid value 0.3 mg KOH / g), which is a polyester composed of adipic acid, and 357 parts by mass of methyl ethyl ketone and sufficiently stir and further add 2,2-dimethylol propionic acid 26 parts by mass were added, then 111 parts by mass of tolylene diisocyanate and 0.2 parts by mass of tin octylate were added and reacted at 75 ° C. for 8 hours. Then, after confirming that the isocyanate content was 0.1% or less, the system was cooled to 50 ° C., 20 parts by mass of triethylamine was added for neutralization, and further, 1600 parts by mass of water was added for emulsification dispersion. The obtained emulsion was desolvated to obtain an aqueous dispersion of urethane resin (RB-1) having a nonvolatile content of 25% by mass. The carboxyl group concentration of the urethane resin (RB-1) was 0.429 mmol / g, the weight average molecular weight was 40,000, and the glass transition temperature was -15 ° C.

Production Example 6: Synthesis of Urethane Resin (RB-2)
15 parts by mass of polyester polyol (b-1) and 30 parts by mass of methyl ethyl ketone were added to a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, and a dropping device, and sufficiently stirred and dissolved. Next, 63 parts by mass of isophorone diisocyanate and 0.1 parts by mass of tin octylate were added and reacted at 80 ° C. for 3 hours. Then, 125 parts by mass of methyl ethyl ketone is added, and after cooling to 60 ° C., polybutylene adipate (a hydroxyl value of 112 mg KOH /, which is a polyester consisting of 6 parts by mass of 2,2-dimethylol propionic acid, 1,4-butylene glycol and adipic acid) 160 parts by mass of g, acid value 0.3 mg KOH / g) were added and the reaction was carried out at 80.degree. Then, after confirming that the isocyanate content has become 1.3% or less, cool to 40 ° C., add 4.5 parts by mass of triethylamine and then 800 parts by mass of water and sufficiently mix by stirring, then 10% piperazine An aqueous solution of 49 parts by mass (90 equivalent% as amine group based on the remaining isocyanate group) was added and emulsified and dispersed. The obtained emulsion was desolventized to obtain an aqueous dispersion of a urethane resin (RB-2) having a sulfonate group having a nonvolatile content of 25% by mass and a carboxyl group. The concentration of the sulfonate group of the urethane resin (RB-2) is 0.065 mmol / g, the concentration of the carboxyl group is 0.183 mmol / g, the weight average molecular weight is 90,000, and the glass transition temperature is -38. It was ° C.

Example 1: Preparation and evaluation of carbon fiber sizing agent (1)
233 parts by weight of the aqueous dispersion of the urethane-modified epoxy resin (A-1) obtained in Production Example 1 (70 parts by weight as the urethane-modified epoxy resin (A-1)), and the sulfonate group obtained in Production Example 4 60 mass parts (30 mass parts as urethane resin (B-1) which has a sulfonic acid group) of the water dispersion of the urethane resin (B-1) which has, and 5 mass% of nonvolatile content by mixing ion-exchange water A carbon fiber sizing agent (1) was prepared.

[Storage stability of epoxy group of carbon fiber sizing agent]
The carbon fiber sizing agent (1) obtained above was stored at 35 ° C. for 7 days, and the epoxy equivalents before and after storage were measured by the pyridine hydrochloride method to calculate the residual ratio of the epoxy group.
“Remaining ratio of epoxy group (%)” = “epoxy equivalent before storage (g / equivalent)” / “epoxy equivalent after storage (g / equivalent)” × 100

[Production of carbon fiber strands]
No-size yarns of polyacrylonitrile carbon fiber (diameter 7 μm / 6000) are bundled, impregnated with carbon fiber sizing agent (1) by immersion method, and squeezed with a roller to adjust the adhesion amount of the active ingredient to 1 mass% Then, heat treatment was carried out at 150 ° C. for 30 minutes to obtain carbon fiber strands (1).

[Evaluation of abrasion resistance]
A carbon fiber strand (1) is rubbed 1000 times with 50 g of tension via three specular chrome plated stainless steel needles arranged in a zigzag manner using a TM type friction conjugation tester TM-200 (manufactured by Daiei Kagaku Seiki Seisakusho) The state of fuzz was visually determined according to the following criteria (reciprocation speed 300 times / min).
:: No fluff was observed at all as in the case of rubbing.
○: Although several fluffs were observed, they were at a practically acceptable level.
Δ: Fluffing was confirmed and thread breakage was slightly observed.
X: A large number of fuzz and yarn breakage of single yarn could be confirmed.

[Fabrication of carbon fiber chopped strands]
No-size yarns of polyacrylonitrile carbon fiber (diameter 7 μm / 6000) are bundled, impregnated with carbon fiber sizing agent (1) by immersion method, and squeezed with a roller to adjust the adhesion amount of the active ingredient to 1 mass% Then, a carbon fiber chopped strand (1) was obtained by cutting to a length of 5 mm with a roving cutter and subsequently heat treating at 150 ° C. for 30 minutes.

[Evaluation of fiber convergence]
Fifty carbon fiber chopped strands (1) were extracted and evaluated according to the following criteria from the number of loosened carbon fibers and fuzzing visually observed.
: 0: 0 ○: 1 to 5 △: 6 to 30 ×: 31 or more

[Preparation of epoxy resin molded article]
50 parts by mass of bisphenol A epoxy resin ("Epiclon 850S" manufactured by DIC Corporation), 20 parts by mass of bisphenol A epoxy resin ("Epiclon 1050" manufactured by DIC Corporation), Cresol novolac epoxy resin ("Epiclon manufactured by DIC Corporation" 673 ") 30 parts by weight of 4 parts by weight of dicyandiamide and 4 parts by weight of N- (3,4-dichlorophenyl) -N ', N'-dimethylurea were prepared and coated on a release paper. The carbon fiber strands (1) obtained above are aligned in one direction at equal intervals on the coated resin film, and then heated to impregnate the epoxy resin, thereby forming a prepreg having a carbon fiber content of 60% by volume. did. The prepared prepreg was laminated, and treated at 150 ° C. under pressure for 1 hour, and subsequently treated at 140 ° C. for 4 hours to produce an epoxy resin molded product (1).

[Evaluation of interlaminar shear strength of epoxy resin molded article]
The interlaminar shear strength was measured on the test plate of thickness 2.5 mm and width 6.0 mm of the epoxy resin molded product (1) by a method according to ASTM D-2344.

[Production of Polyamide Resin Molded Article]
The carbon fiber chopped strand (1) obtained above and 6,6-nylon resin pellets (general-purpose injection molding grade) are compounded by a twin-screw extrusion kneader so that the carbon fiber content is 30% by mass. , 3 mm × × 3 mm long compound pellets. After drying the compound pellets, a polyamide resin molded product (1) was produced by injection molding.

[Evaluation of bending strength of polyamide resin molded article]
The bending strength of the polyamide resin molded product (1) was measured by the method according to ISO178.

(Example 2: Synthesis and evaluation of carbon fiber sizing agent (2))
283 parts by mass (85 parts by mass as a urethane-modified epoxy resin (A-2)) of the aqueous dispersion of the urethane-modified epoxy resin (A-2) obtained in Production Example 2 and the sulfonate group obtained in Preparation Example 4 50 mass parts (15 mass parts as urethane resin (B-1) which has a sulfonate group) of the water dispersion of the urethane resin (B-1) which has, and 5 mass% of non volatile matters by mixing ion-exchange water A carbon fiber sizing agent (2) was prepared.

  Each evaluation was performed in the same manner as in Example 1 except that the carbon fiber sizing agent (2) was used instead of the carbon fiber sizing agent (1).

(Comparative example 1: Preparation and evaluation of carbon fiber sizing agent (R1))
A carbon fiber sizing agent (R1) having a nonvolatile content of 5% by mass was prepared by mixing a urethane-modified epoxy resin (A-1) and ion exchange water.

  Each evaluation was performed in the same manner as in Example 1 except that the carbon fiber sizing agent (R1) was used instead of the carbon fiber sizing agent (1).

(Comparative example 2: Preparation and evaluation of carbon fiber sizing agent (R2))
A carbon fiber sizing agent (R2) having a nonvolatile content of 5% by mass was prepared by mixing a urethane resin (B-1) having a sulfonate group and ion-exchanged water.

  Each evaluation was performed in the same manner as in Example 1 except that a carbon fiber sizing agent (R2) was used instead of the carbon fiber sizing agent (1).

(Comparative example 3: Preparation and evaluation of carbon fiber sizing agent (R3))
233 parts by weight of the aqueous dispersion of the urethane-modified epoxy resin (A-1) obtained in Production Example 1 (70 parts by weight as the urethane-modified epoxy resin (A-1)), the urethane resin obtained in Production Example 5 (RB A carbon fiber sizing agent (R3) having a nonvolatile content of 5% by mass was prepared by mixing 120 parts by mass of the aqueous dispersion of (1) (30 parts by mass as a urethane resin (RB-1)) and ion-exchanged water .

  Each evaluation was performed in the same manner as in Example 1 except that a carbon fiber sizing agent (R3) was used instead of the carbon fiber sizing agent (1).

(Comparative example 4: Preparation and evaluation of carbon fiber sizing agent (R4))
200 parts by weight of the aqueous dispersion of the urethane-modified epoxy resin (A-1) obtained in Production Example 1 (60 parts by weight as the urethane-modified epoxy resin (A-1)), the urethane resin obtained in Production Example 6 (RB A carbon fiber sizing agent with a non-volatile content of 5% by mass (R4) by mixing 160 parts by mass of the aqueous dispersion (2) (40 parts by mass as a urethane resin (RB-2) having a carboxyl group) and ion-exchanged water Were prepared.

  Each evaluation was performed in the same manner as in Example 1 except that a carbon fiber sizing agent (R4) was used instead of the carbon fiber sizing agent (1).

  Table 1 shows the evaluation results of Examples 1 and 2 and Comparative Examples 1 to 4 described above.

  The thing of Examples 1-2 which is a fiber sizing agent of this invention had the high residual ratio of an epoxy group, and was excellent in abrasion resistance and fiber focusing property. Moreover, it was confirmed that the molded article obtained using this is excellent in strength whether the matrix resin is a thermosetting resin or a thermoplastic resin.

  On the other hand, Comparative Example 1 is an example in which the urethane resin having a sulfonate group is not contained, but it was confirmed that the fiber bundling property is inferior.

  Although the comparative example 2 is an example which does not contain a urethane modified epoxy resin, when matrix resin is an epoxy resin, it was confirmed that the intensity | strength of the molded article obtained using this is inadequate.

  Comparative Example 3 is an example which does not have a sulfonate group but contains a urethane resin having a carboxyl group, but it is confirmed that the residual rate of the epoxy group is low, and the abrasion resistance and the fiber convergence are insufficient. It was done. Moreover, it was confirmed that the molded products obtained using this have insufficient strength.

  Comparative Example 4 is an example where the carboxyl group concentration in the urethane resin having a sulfonate group exceeds the upper limit of 0.05 mmol / g, but the residual rate of the epoxy group is low, and the scratch resistance is insufficient. That was confirmed. Moreover, it was confirmed that the molded products obtained using this have insufficient strength.

Claims (4)

  A carbon fiber sizing agent comprising a urethane-modified epoxy resin (A) having an alkoxypolyoxyalkylene structure, a urethane resin (B) having a sulfonate group, and an aqueous medium, wherein the carboxyl group in the urethane resin (B) A carbon fiber sizing agent having a concentration of 0.05 mmol / g or less.   At least one epoxy resin selected from the group consisting of a phenol novolac epoxy resin having a hydroxyl group, a cresol novolac epoxy resin having a hydroxyl group, and a bisphenol A epoxy resin having a hydroxyl group, as the urethane-modified epoxy resin (A) The carbon fiber sizing agent according to claim 1, which is obtained as a raw material.   The carbon fiber sizing agent according to claim 1 or 2, wherein the urethane resin (B) having a sulfonate group is obtained using a polyester polyol having a sulfonate group as a raw material.   A carbon fiber characterized by being collected by the fiber sizing agent according to any one of claims 1 to 3.