JP6115461B2 - Carbon fiber coated with sizing agent and method for producing the same, carbon fiber reinforced thermoplastic resin composition - Google Patents

Description

  The present invention relates to a sizing agent-coated carbon fiber suitable for use in aircraft members, spacecraft members, automobile members, marine members, sports applications such as golf shafts and fishing rods, and other general industrial applications, and the sizing agent-coated carbon fibers. It is related with the manufacturing method. More specifically, the present invention provides excellent adhesion and storage stability when using an epoxy resin suitable as a structural material as a matrix resin, as well as excellent heat resistance and mechanical strength in severe usage environments such as low temperatures. The present invention relates to a sizing agent-coated carbon fiber capable of obtaining an excellent carbon fiber-reinforced composite material and a method for producing the sizing agent-coated carbon fiber.

  Since carbon fiber is lightweight and has excellent strength and elastic modulus, many composite materials combined with various matrix resins are used for aircraft members, spacecraft members, automobile members, ship members, civil engineering and building materials, and sporting goods. Used in the field. In a composite material using carbon fibers, in order to make use of the excellent characteristics of carbon fibers, it is important that the adhesion between the carbon fibers and the matrix resin is excellent.

  In order to improve the adhesion between the carbon fiber and the matrix resin, a method of introducing an oxygen-containing functional group on the surface of the carbon fiber is usually performed by subjecting the carbon fiber to oxidation treatment such as gas phase oxidation or liquid phase oxidation. . For example, a method of improving the interlaminar shear strength, which is an index of adhesiveness, by subjecting carbon fibers to electrolytic treatment has been proposed (see Patent Document 1). However, in recent years, as the level of required properties for composite materials has improved, the adhesion that can be achieved by such oxidation treatment alone is becoming insufficient.

  On the other hand, since carbon fiber is brittle and has poor convergence and friction resistance, fluff and yarn breakage are likely to occur in the high-order processing step. For this reason, the method of apply | coating a sizing agent to carbon fiber is proposed (refer patent document 2 and 3).

  For example, compounds having a plurality of aliphatic type epoxy groups have been proposed as sizing agents (see Patent Documents 4, 5, and 6). Further, a method of applying an epoxy adduct of polyalkylene glycol as a sizing agent to carbon fibers has been proposed (see Patent Documents 7, 8 and 9).

  In addition, a method of applying diglycidyl ether of bisphenol A to carbon fibers as an aromatic sizing agent has been proposed (see Patent Documents 2 and 3). In addition, a method of applying a polyalkylene oxide adduct of bisphenol A as a sizing agent to carbon fibers has been proposed (see Patent Documents 10 and 11). In addition, a method of applying a bisphenol A polyalkylene oxide adduct having an epoxy group added thereto to a carbon fiber as a sizing agent has been proposed (see Patent Documents 12 and 13).

  Although the above-described sizing agent can impart adhesion and convergence to the carbon fiber, a sizing agent composed of one kind of epoxy compound is not sufficient, and two or more kinds of epoxy compounds are used in combination depending on the desired function. Techniques have been proposed in recent years.

  For example, a sizing agent that combines two or more epoxy compounds that define surface free energy has been proposed (see Patent Documents 14 to 17). Patent Document 14 discloses a combination of an aliphatic epoxy compound and an aromatic epoxy compound. According to Patent Document 14, the sizing agent that is abundant in the outer layer provides a shielding effect against the atmosphere with respect to the sizing agent component that is abundant in the inner layer, thereby improving environmental resistance. Moreover, in this patent document 14, about the preferable range of a sizing agent, the ratio of an aliphatic epoxy compound and an aromatic epoxy compound is prescribed | regulated as 10 / 90-40 / 60, and the one where the amount of aromatic epoxy compounds is larger is suitable. Has been.

  Patent Documents 16 and 17 disclose a sizing agent using two or more epoxy compounds having different surface free energies. The Patent Documents 16 and 17 mainly aim to improve the permeability of a matrix resin by using a sizing agent containing two or more epoxy compounds having different surface free energies, and two or more epoxy compounds. The combination of the aromatic epoxy compound and the aliphatic epoxy compound is not limited as a combination of the above, and there is no general illustration of the aliphatic epoxy compound selected from the viewpoint of adhesiveness.

  Furthermore, the sizing agent which mix | blends a bisphenol A type epoxy compound and aliphatic polyepoxy resin by mass ratio 50 / 50-90 / 10 is disclosed (refer patent document 18). However, Patent Document 18 also has a large amount of bisphenol A type epoxy compound, which is an aromatic epoxy compound.

  In addition, as a sizing agent that defines a combination of an aromatic epoxy compound and an aliphatic epoxy compound, a polyfunctional aliphatic compound on the surface of the carbon fiber bundle, an epoxy resin on the upper surface, an alkylene oxide adduct and an unsaturated dibasic acid A combination of a condensate and an alkylene oxide adduct of phenols is disclosed (see Patent Document 19).

  Furthermore, as a combination of two or more epoxy compounds, a combination of an aliphatic epoxy compound and a bisphenol A type epoxy compound that is an aromatic epoxy compound is disclosed. The aliphatic epoxy compound is a cycloaliphatic epoxy compound and / or a long-chain aliphatic epoxy compound (see Patent Document 20).

  Further, combinations of epoxy compounds having different properties are disclosed. A combination of two epoxy compounds that are liquid and solid at 25 ° C. is disclosed (see Patent Document 21). Furthermore, combinations of epoxy resins having different molecular weights, and combinations of monofunctional aliphatic epoxy compounds and epoxy resins have been proposed (see Patent Documents 22 and 23).

  However, in reality, the adhesiveness and the stability of the carbon fiber when stored in a wet environment cannot be said to be satisfied at the same time even in a sizing agent (for example, Patent Documents 20 to 23, etc.) in which two or more kinds are mixed. there were. The reason for this is that it is necessary to satisfy the following three requirements in order to satisfy both high adhesiveness and the suppression of deterioration of physical properties of carbon fiber when stored in a wet environment. This is because they did not meet these requirements. The first of the three requirements is that an epoxy component with high adhesiveness is present inside the sizing layer (carbon fiber side), and the carbon fiber and the epoxy compound in the sizing interact strongly. The sizing layer surface layer (matrix resin side) has a function of inhibiting the contact between the epoxy compound having high adhesion to the carbon fiber in the inner layer and moisture in the atmosphere, and the third is In order to improve the adhesion with the matrix resin, the sizing agent surface layer (matrix resin side) needs to have a chemical composition capable of strong interaction with the matrix resin.

  For example, Patent Document 14 discloses that the sizing agent has an inclined structure in order to enhance the adhesion between the carbon fiber and the sizing agent, but in any other document (Patent Documents 15 to 18 and the like). However, it can be said that there is no idea that the surface of the sizing layer simultaneously satisfies that the contact between the carbon fiber and moisture in the atmosphere is inhibited and that high adhesion to the matrix resin is realized.

  Patent Document 19 discloses that a polyfunctional aliphatic compound is present in the inner layer of the sizing agent, and an aromatic epoxy resin and an aromatic-based reactant having low reactivity are present in the outer layer, which are retained for a long time. In such a case, it can be expected that the change of the prepreg with time is suppressed, but since there is no polyfunctional aliphatic compound having high adhesion on the surface layer of the sizing agent, it is difficult to achieve high adhesion with the matrix resin.

Japanese Patent Laid-Open No. 04-361619 US Pat. No. 3,957,716 JP-A-57-171767 Japanese Examined Patent Publication No. 63-14114 JP-A-7-279040 JP-A-8-113876 JP-A-57-128266 U.S. Pat. No. 4,555,446 JP 62-033872 A JP 07-009444 A JP 2000-336577 A JP 61-028074 A Japanese Patent Laid-Open No. 01-272867 JP 2005-179826 A JP 2005-256226 A International Publication No. 03/010383 JP 2008-280624 A JP 2005-213687 A JP 2002-309487 A Japanese Patent Laid-Open No. 02-307979 JP 2002-173873 A JP 59-71479 A JP 58-41973 A

  The present invention has been made in view of the above, and is a carbon fiber reinforced composite material that is excellent in adhesiveness and storage stability and excellent in heat resistance and mechanical strength in severe use environments such as under low temperature. It is an object of the present invention to provide a sizing agent-coated carbon fiber that can be obtained and a method for producing a sizing agent-coated carbon fiber.

In order to solve the above-described problems and achieve the object, the present invention provides at least ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol. , Polypropylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, polybutylene glycol, 1,5-pentanediol, glycerol, di At least one selected from the group consisting of glycerol, polyglycerol, trimethylolpropane, pentaerythritol, sorbitol, and arabitol, and epichlorohydrin, Glycidyl ether type epoxy compound obtained by reacting a water-soluble epoxy compound (A) and non-water-soluble epoxy compound sizing agent comprising (B) a sizing agent applying carbon fibers coated in carbon fiber, X-rays of 400eV Of the component of the binding energy (284.6 eV) attributed to (a) CHx, C-C, C = C in the C1s inner-shell spectrum measured at a photoelectron escape angle of 55 ° by X-ray photoelectron spectroscopy using (I), (II) obtained from the ratio (a) / (b) between the height (cps) and the height (cps) of the component of the binding energy (286.1 eV) attributed to C—O (b) ) Satisfies the relationship (III).
(I) Value of (a) / (b) on the surface of the carbon fiber coated with the sizing agent
(II) The surface of the sizing agent-coated carbon fiber cleaned by sonicating the sizing agent-coated carbon fiber in an acetone solvent to 0.09 to 0.20% by mass of (a) / Value of (b)
(III) 0.50 ≦ (I) ≦ 0.90 and 0.6 <(II) / (I) <1.0.

  In the sizing agent-coated carbon fiber of the present invention, the water-soluble epoxy compound (A) has an epoxy value of 2.0 to 8.0 meq / g and a hydroxyl value of 2.0 to 5.0 meq / g. And having two or more epoxy groups in the molecule.

  Moreover, the preferable sizing agent-coated carbon fiber of the present invention is characterized in that, in the above invention, the water-insoluble epoxy compound (B) is an aromatic epoxy compound (B1) having one or more aromatic rings in the molecule. To do.

In a preferred sizing agent-coated carbon fiber of the present invention, the aromatic epoxy compound (B1) is a bisphenol A type epoxy compound or a bisphenol F type epoxy compound in the above invention.
The mass ratio of the water-soluble epoxy compound (A) and the water-insoluble epoxy compound (B) in the sizing agent is 52/48 to 80/20.

  Further, the preferred sizing agent-coated carbon fiber of the present invention is the above invention, wherein the surface carboxyl group concentration COOH / C of the carbon fiber measured by chemical modification X-ray photoelectron spectroscopy is 0.003 to 0.015, surface hydroxyl group The concentration COH / C is 0.001 to 0.050.

  Moreover, the manufacturing method of the sizing agent application | coating carbon fiber of this invention is the sizing agent application | coating carbon fiber which apply | coated the sizing agent containing the water-soluble epoxy compound (A) and the water-insoluble epoxy compound (B) to carbon fiber in the said invention. The method is characterized in that after the sizing agent is applied to the carbon fiber, heat treatment is performed in a temperature range of 160 to 260 ° C. for 30 to 600 seconds.

  Further, in the method for producing a preferred sizing agent-coated carbon fiber of the present invention, in the above invention, an aqueous emulsion liquid containing at least the water-insoluble epoxy compound (B) is present in the aqueous solution containing at least the water-soluble epoxy compound (A). A sizing agent-containing liquid is applied to the carbon fiber.

  Moreover, the manufacturing method of the preferable sizing agent application | coating carbon fiber of this invention is the density | concentration of 0.1-50 mass% after making water-soluble epoxy compound (A) into 0.1-50 mass% aqueous solution in the said invention. The sizing agent-containing liquid obtained by mixing with the aqueous emulsion (B) aqueous solution is applied to the carbon fiber.

  Further, in the method for producing a preferred sizing agent-coated carbon fiber of the present invention, in the above invention, the particle size measured by a particle size distribution meter of an aqueous emulsion containing at least the water-insoluble epoxy compound (B) is 100 to 600 nanometers. It is characterized by being.

  Further, a preferred carbon fiber reinforced thermoplastic resin composition of the present invention is a sizing agent-coated carbon fiber described above or a sizing agent-coated carbon fiber manufactured by the method for manufacturing a sizing agent-coated carbon fiber described above, and It comprises a thermoplastic resin.

  Moreover, the preferable carbon fiber reinforced thermoplastic resin composition of the present invention is a molded product of the above-described carbon fiber reinforced thermoplastic resin composition having a bending strength (S1) before being immersed in hot water at 80 ° C. and 80 ° C. The ratio (S2 / S1) to the bending strength (S2) after being immersed in hot water for 1000 hours is 0.75 or more.

  In a preferred carbon fiber reinforced thermoplastic resin composition of the present invention, the thermoplastic resin is at least one selected from the group consisting of a polyarylene sulfide resin, a polycarbonate resin and a polyolefin resin.

  According to the present invention, there is obtained a sizing agent-coated carbon fiber capable of producing a carbon fiber reinforced composite material having excellent adhesiveness with a matrix resin, little change over time during storage in a wet environment, and excellent heat resistance and strength characteristics. be able to.

  Hereinafter, the form for enforcing the manufacturing method of the sizing agent application | coating carbon fiber of this invention and the sizing agent application | coating carbon fiber of this invention is demonstrated.

The present invention relates to a sizing agent-coated carbon fiber obtained by coating a carbon fiber with a sizing agent containing at least a water-soluble epoxy compound (A) and a water-insoluble epoxy compound (B), and an X-ray photoelectron using X-rays of 400 eV The height (cps) of the component of the binding energy (284.6 eV) attributed to (a) CHx, C-C, C = C in the C _1s core spectrum measured at a photoelectron escape angle of 55 ° by spectroscopy. (B) The values of (I) and (II) obtained from the ratio (a) / (b) of the binding energy (286.1 eV) attributed to C—O and the height (cps) of the component are ( It is characterized by satisfying the relationship of III).
(I) The value of (a) / (b) on the surface of the sizing agent-coated carbon fiber (II) The sizing agent-coated carbon fiber is sonicated in an acetone solvent, so that the sizing agent adhesion amount is 0.09. (A) / (b) value (III) 0.50 ≦ (I) ≦ 0.90 and 0.6 <(II) / () of the surface of the carbon fiber coated with the sizing agent washed to ˜0.20% by mass I) <1.0.

  First, the sizing agent used in the present invention will be described. The sizing agent according to the present invention includes at least a water-soluble epoxy compound (A) and a water-insoluble epoxy compound (B).

  The water-soluble epoxy compound (A) in the present invention is a mixture of 10 parts by mass of an epoxy compound with 90 parts by mass of water at 25 ° C., stirred with a stirrer for 24 hours or more, and corresponds to one type of JIS P3801 (1956). It is assumed that the weight of the solid remaining after filtering with a filter paper is less than 60% of the mass of the epoxy compound initially mixed. The thing in which 60% or more of solid matter remains in the above method is assumed to be the water-insoluble epoxy compound (B) in the present invention.

  According to the knowledge of the present inventors, such a range is excellent in the interfacial adhesion between the carbon fiber and the matrix, and when the sizing agent-coated carbon fiber is used in a prepreg after storage in a wet environment, the change with time is small. It is suitable for carbon fiber for composite materials.

  When the sizing agent according to the present invention is applied to carbon fibers, a large amount of water-soluble epoxy compound (A) is present on the inner side (carbon fiber side) of the sizing layer, so that carbon fiber and water-soluble epoxy compound (A) are present. It strongly interacts and enhances adhesion, and the presence of a large amount of water-insoluble epoxy compound (B) on the sizing layer surface (matrix resin side) inhibits the ingress of moisture from the outside, As a chemical composition capable of strong interaction with the matrix resin on the sizing layer surface layer (matrix resin side) while suppressing ring opening of the epoxy, a water-insoluble epoxy compound (B) containing a predetermined proportion of epoxy groups is predetermined. Since it exists in a ratio, the adhesiveness with the matrix resin is also improved.

  When the sizing agent consists only of the water-insoluble epoxy compound (B) and does not contain the water-soluble epoxy compound (A), the moisture absorption rate is low, and when the carbon fiber is stored in a humid environment, the sizing agent epoxy There is an advantage that ring opening of the group is difficult to occur and a change in physical properties is small. However, since the water-insoluble epoxy compound (B) has low polarity and is difficult to wet the surface-treated carbon fiber, the adhesion between the carbon fiber and the matrix resin is inferior to that of the water-soluble epoxy compound (A). It has been confirmed.

  In addition, when the sizing agent is composed of only the water-soluble epoxy compound (A), it has been confirmed that the carbon fiber coated with the sizing agent has high adhesiveness with the matrix resin. Although the mechanism is not certain, the water-soluble epoxy compound (A) has high polarity and is easily wetted to the surface-treated carbon fiber. Therefore, a functional group such as a carboxyl group and a hydroxyl group on the surface of the carbon fiber and a water-soluble epoxy compound ( It is believed that A) can form a strong interaction. However, the water-soluble epoxy compound (A) exhibits high adhesiveness due to the interaction with the carbon fiber surface, and has a high moisture absorption rate. When the carbon fiber is stored in a humid environment, the epoxy group of the sizing agent is used. Has been confirmed to have a problem that the physical properties of the carbon fiber reinforced composite material using the carbon fiber are lowered.

  In the present invention, when the water-soluble epoxy compound (A) and the water-insoluble epoxy compound (B) are mixed, the water-soluble epoxy compound (A) having a higher polarity is unevenly distributed on the carbon fiber side and is opposite to the carbon fiber. There is a phenomenon that the non-polar water-insoluble epoxy compound (B) having a low polarity tends to be unevenly distributed in the outermost layer of the sizing layer. As a result of the inclined structure of the sizing layer, the water-soluble epoxy compound (A) can enhance the adhesion between the carbon fiber and the matrix resin by having a strong interaction with the carbon fiber in the vicinity of the carbon fiber. Further, when storing the carbon fiber, the water-insoluble epoxy compound (B) present in a large amount in the outer layer plays a role of blocking the water-soluble epoxy compound (A) from moisture. Thereby, since the ring-opening reaction due to moisture of the water-soluble epoxy compound (A) is suppressed, stability during long-term storage is expressed. When the water-soluble epoxy compound (A) is almost completely covered with the water-insoluble epoxy compound (B), the interaction between the sizing agent and the matrix resin is reduced and the adhesiveness is lowered. The ratio of the water-soluble epoxy compound (A) and the water-insoluble epoxy compound (B) on the surface is important.

The sizing agent-coated carbon fiber according to the present invention has a C _1s inner shell spectrum (a) measured on the surface of the sizing agent coated on the carbon fiber by X-ray photoelectron spectroscopy using X-rays of 400 eV at a photoelectron escape angle of 55 °. ) The height (cps) of the component of the bond energy (284.6 eV) attributed to CHx, C—C, C = C, and (b) the component of the bond energy (286.1 eV) attributed to C—O. It is preferable that the values of (I) and (II) obtained from the ratio (a) / (b) to the height (cps) satisfy the relationship (III).
(I) The value of (a) / (b) on the surface of the sizing agent-coated carbon fiber before sonication (II) The sizing agent-coated carbon fiber is sonicated in an acetone solvent to reduce the sizing agent adhesion amount. (A) / (b) value (III) 0.50 ≦ (I) ≦ 0.90 and 0.6 <(II) on the surface of the sizing agent-coated carbon fiber cleaned to 0.09 to 0.20% by mass ) / (I) <1.0.

  The fact that (I), which is the value (a) / (b) of the surface of the sizing agent-coated carbon fiber before ultrasonic treatment, falls within the range of (III) above indicates that C- It shows that there are few compounds which have O bond. (I) is preferably 0.55 or more, more preferably 0.57 or more. Further, (I) is preferably 0.80 or less, more preferably 0.74 or less.

  Compared with the sizing agent surface, (II) / (I), which is the ratio of (a) / (b) values of the sizing agent-coated carbon fiber surface before and after the ultrasonic treatment, falls within the range of (III) above. In the inner layer of the sizing agent layer, the ratio of the compound having a C—O bond having high polarity is high. (II) / (I) is preferably 0.65 or more. Further, (II) / (I) is preferably 0.85 or less.

  When the values of (I) and (II) satisfy the relationship of (III), the adhesive with the matrix resin is excellent, and when the sizing coated carbon fiber is stored in a humid environment, the sizing agent coated carbon The carbon fiber reinforced composite material using fibers is preferable because the decrease in physical properties is small. In addition, the ultrasonic treatment described here means that 2 g of sizing agent-coated carbon fiber is immersed in 50 ml of acetone and ultrasonic cleaning is performed for 30 minutes three times, followed by immersion in 50 ml of methanol and ultrasonic cleaning 30. It means the process of performing a minute once and drying.

  The measurement method of X-ray photoelectron spectroscopy is an analysis method in which a sample carbon fiber is irradiated with X-rays in an ultra-high vacuum and the kinetic energy of photoelectrons emitted from the surface of the carbon fiber is measured with an energy analyzer. . By examining the kinetic energy of the photoelectrons emitted from the carbon fiber surface of the sample, the binding energy converted from the energy value of the X-rays incident on the carbon fiber of the sample is uniquely determined. From the binding energy and the photoelectron intensity The type and concentration of elements present on the outermost surface (˜nm) of the sample and the chemical state thereof can be analyzed.

In the present invention, the peak ratio of (a) and (b) on the sizing agent surface of the sizing agent-coated carbon fiber is determined by X-ray photoelectron spectroscopy according to the following procedure. The sizing agent-coated carbon fibers were cut to 20 mm, spread and arranged on a copper sample support, and then Saga synchrotron was used as an X-ray source, and the excitation energy was measured at 400 eV and the photoelectron escape angle was 55 °. Measurement is performed while keeping the sample chamber at 1 × 10 ⁻⁸ Torr. As correction of the peak accompanying charging during measurement, first, the binding energy value of the main peak of C _1s is adjusted to 284.6 eV. At this time, the peak area of C _1s is obtained by drawing a straight baseline in the range of 282 to 296 eV. Further, a linear base line of 282 to 296 eV whose area was obtained at the C _1s peak was defined as the origin (zero point) of photoelectron intensity, and (a) a binding energy 284 attributed to CHx, CC, C = C. The peak height (cps) of .6 eV (cps: photoelectron intensity per unit time) and (b) the peak height (cps) of the binding energy 286.1 eV attributed to the CO component are determined. b) is calculated.

  In this invention, it is preferable that the adhesion amount to the carbon fiber of a sizing agent is the range of 0.1-10.0 mass% with respect to sizing agent application | coating carbon fiber, More preferably, 0.2-3. It is in the range of 0% by mass. When the sizing agent adhesion amount is 0.1% by mass or more, when the sizing agent-coated carbon fiber is prepreg and weaved, it can withstand friction caused by a metal guide that passes therethrough, and generation of fluff can be suppressed. Excellent quality such as smoothness of fiber sheet. On the other hand, when the adhesion amount of the sizing agent is 10.0% by mass or less, the matrix resin is impregnated inside the carbon fiber without being hindered by the sizing agent film around the sizing agent-coated carbon fiber, and in the obtained composite material The generation of voids is suppressed, the quality of the composite material is excellent, and at the same time the mechanical properties are excellent.

  The amount of sizing agent attached was measured by measuring the change in mass before and after the heat treatment when about 2 ± 0.5 g of sizing agent-coated carbon fiber was sampled and heat-treated at 450 ° C. for 15 minutes in a nitrogen atmosphere. The mass change is divided by the mass before heat treatment (mass%).

  In the present invention, the thickness of the sizing agent layer applied to the carbon fiber and dried is preferably within a range of 2.0 to 20 nm, and the maximum value of the thickness does not exceed twice the minimum value. With such a uniform sizing agent layer, a large effect of improving adhesiveness can be obtained stably, and further, stable high-order workability can be obtained.

  In this invention, it is preferable that the adhesion amount to the carbon fiber of a water-soluble epoxy compound (A) is the range of 0.05-5.0 mass% with respect to sizing agent application | coating carbon fiber, More preferably, it is 0. .2 to 2.0% by mass. More preferably, it is 0.3-1.0 mass%. The adhesion amount of the water-soluble epoxy compound (A) is preferably 0.05% by mass or more, because the adhesion between the sizing agent-coated carbon fiber and the matrix resin is improved.

  In the present invention, the sizing agent contains at least a water-soluble epoxy compound (A) and a water-insoluble epoxy compound (B). The mass ratio (A) / (B) of the water-soluble epoxy compound (A) and the water-insoluble epoxy compound (B) is preferably 52/48 to 80/20. By setting (A) / (B) to 52/48 or more, the ratio of the water-soluble epoxy compound (A) present on the carbon fiber surface is increased, and the adhesion between the carbon fiber and the matrix resin is improved. As a result, composite properties such as tensile strength of the obtained carbon fiber reinforced composite material are enhanced. Further, by setting (A) / (B) to 80/20 or less, the amount of highly reactive water-soluble epoxy compound (A) present on the surface of the carbon fiber is reduced, and contact with moisture in the atmosphere is reduced. Since it can suppress, it is preferable. The mass ratio of (A) / (B) is more preferably 55/45 or more, and further preferably 60/40 or more. The mass ratio of (A) / (B) is more preferably 75/35 or less, and further preferably 73/37 or less.

  In the present invention, the water-soluble epoxy compound (A) has one or more epoxy groups in the molecule. As a result, a strong bond between the carbon fiber and the epoxy group in the sizing agent can be formed. The number of epoxy groups in the molecule is preferably 2 or more, and more preferably 3 or more. When the water-soluble epoxy compound (A) is an epoxy compound having two or more epoxy groups in the molecule, even if one epoxy group forms a covalent bond with an oxygen-containing functional group on the surface of the carbon fiber, it remains The epoxy group can form a covalent bond or a hydrogen bond with the matrix resin, and the adhesion can be further improved. There is no particular upper limit on the number of epoxy groups, but 10 is sufficient from the viewpoint of adhesion.

  In the present invention, the water-soluble epoxy compound (A) is preferably an epoxy compound having 3 or more functional groups of 2 or more, more preferably an epoxy compound having 4 or more of 2 or more functional groups. preferable. The functional group possessed by the epoxy compound is preferably selected from a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, or a sulfo group in addition to the epoxy group. When the water-soluble epoxy compound (A) is an epoxy compound having three or more epoxy groups or other functional groups in the molecule, one epoxy group forms a covalent bond with the oxygen-containing functional group on the carbon fiber surface. Even in this case, the remaining two or more epoxy groups or other functional groups can form a covalent bond or a hydrogen bond with the matrix resin, and the adhesion is further improved. There is no particular upper limit on the number of functional groups containing an epoxy group, but 10 is sufficient from the viewpoint of adhesiveness.

  The epoxy value of the water-soluble epoxy compound (A) used in the present invention is preferably 2.0 meq / g or more. When the epoxy value of the water-soluble epoxy compound (A) is 2.0 meq / g or more, an interaction with the carbon fiber is formed at a high density, and the adhesion between the carbon fiber and the matrix resin is further improved. The upper limit of the epoxy value is not particularly limited, but if it is 8.0 meq / g or less, an interaction with the carbon fiber at a high density is formed, which is sufficient from the viewpoint of adhesiveness. The epoxy value of the water-soluble epoxy compound (A) is more preferably 3.0 to 7.0 meq / g.

  The hydroxyl value of the water-soluble epoxy compound (A) used in the present invention is preferably 2.0 to 5.0 meq / g. When the hydroxyl value of the water-soluble epoxy compound (A) is 2.0 meq / g or more, the interaction with polar groups such as hydroxyl groups and carboxyl groups on the carbon fiber surface increases, and the water-soluble epoxy compound ( A) tends to be unevenly distributed, which is preferable. The hydroxyl value of the water-soluble epoxy compound (A) is more preferably 2.5 meq / g or more. When the hydroxyl value is 5.0 meq / g or less, hydrogen bonding between the water-soluble epoxy compounds (A) is suppressed and the viscosity becomes low, so that the handleability is improved and the adhesiveness is improved. Moreover, since an epoxy compound is manufactured by condensing epichlorohydrin with respect to a hydroxyl group, an epoxy value will improve relatively that a hydroxyl value is 5.0 meq or less, and carbon fiber and The adhesiveness of the matrix resin is improved. The hydroxyl value of the water-soluble epoxy compound (A) is more preferably 4.0 meq / g or less.

Furthermore, the water-soluble epoxy compound (A) used in the present invention has two or more epoxy groups in the molecule . When the water-soluble epoxy compound (A) has two or more epoxy groups in the molecule, even when one epoxy group forms a covalent bond with the oxygen-containing functional group on the surface of the carbon fiber, the remaining one or more The epoxy group can form a covalent bond or a hydrogen bond with the matrix resin, and the adhesion is further improved. There is no particular upper limit on the number of functional groups containing an epoxy group, but 10 is sufficient from the viewpoint of adhesiveness.

The water-soluble epoxy compound (A) in the present invention must be a glycidyl ether type epoxy compound having two or more epoxy groups in the molecule from the viewpoint of high adhesiveness.

Specific examples of the water-soluble epoxy compound (A), for example, glycidyl derived ether-type epoxy compounds derived from a polyol, a glycidyl amine type epoxy compounds derived from amines having a plurality active hydrogen, from polycarboxylic acids An ester type epoxy compound and an epoxy compound obtained by oxidizing a compound having a plurality of double bonds in the molecule are included . In the present invention, a glycidyl ether type epoxy compound derived from a polyol is used .

  Examples of the glycidyl ether type epoxy compound include a glycidyl ether type epoxy compound obtained by a reaction between a polyol and epichlorohydrin. For example, as a glycidyl ether type epoxy compound, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, trimethylene glycol, 1, 2 -Butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, polybutylene glycol, 1,5-pentanediol, glycerol, diglycerol, polyglycerol, trimethylolpropane, pentaerythritol , Sorbitol, arabitol, ethylene oxide adduct of phenol, ethylene oxide adduct of bisphenol A And at least one selected from the group consisting of ethylene oxide adduct of bisphenol F, glycidyl ether type epoxy compound obtained by reaction with epichlorohydrin.

  Examples of the water-soluble epoxy compound (A) having a hydroxyl group in addition to the epoxy group include sorbitol-type polyglycidyl ether and glycerol-type polyglycidyl ether. Specifically, “Denacol (registered trademark)” EX-611 is exemplified. , EX-612, EX-614, EX-614B, EX-512, EX-521, EX-421, EX-313, EX-314 and EX-321 (manufactured by Nagase ChemteX Corporation).

The water-soluble epoxy compound (A) used in the present invention is ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, from the viewpoint of high adhesiveness as described above. Tetrapropylene glycol, polypropylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, polybutylene glycol, 1,5-pentanediol, At least one selected from the group consisting of glycerol, diglycerol, polyglycerol, trimethylolpropane, pentaerythritol, sorbitol, and arabitol; Ether-type epoxy compounds obtained by the reaction of Rohidorin is rather good, at least any one of these is used in the present invention.

  In the present invention, the water-soluble epoxy compound (A) is more preferably polyglycerol polyglycidyl ether.

  In the present invention, the water-insoluble epoxy compound (B) has one or more epoxy groups in the molecule. Two or more are preferable, and three or more are more preferable. Moreover, it is preferable that it is 10 or less.

  In the present invention, the water-insoluble epoxy compound (B) is preferably an epoxy compound having 3 or more of two or more functional groups, and preferably an epoxy compound having 4 or more of two or more functional groups. More preferred. The functional group possessed by the water-insoluble epoxy compound (B) is preferably selected from a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, or a sulfo group in addition to the epoxy group. When the water-insoluble epoxy compound (B) is an epoxy compound having three or more epoxy groups or one epoxy group and two or more other functional groups in the molecule, one epoxy group is the carbon fiber surface. Even when a covalent bond is formed with this oxygen-containing functional group, the remaining two or more epoxy groups or other functional groups can form a covalent bond or a hydrogen bond with the matrix resin, and the adhesion is further improved. There is no particular upper limit on the number of functional groups containing an epoxy group, but 10 is sufficient from the viewpoint of adhesiveness.

  In the present invention, the epoxy value of the water-insoluble epoxy compound (B) is preferably 2.0 meq / g or more, more preferably 2.0 to 8.0 meq / g, still more preferably 2.0. Less than ~ 5.0 meq / g. When the epoxy value of the water-insoluble epoxy compound (B) is 2.0 meq / g or more, covalent bonds are formed at a high density, and the adhesion between the carbon fiber and the matrix resin is further improved.

  In the present invention, the water-insoluble epoxy compound (B) can have one or more functional groups in the molecule in addition to the epoxy group. Further, the water-insoluble epoxy compound (B) may be one kind or a combination of a plurality of compounds. The functional group other than the epoxy group is preferably selected from a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, a carboxyl group, an ester group or a sulfo group, and two or more functional groups in one molecule. May be included.

  In the present invention, specific examples of the water-insoluble epoxy compound (B) include, for example, a glycidyl ether type epoxy compound derived from a polyol, a glycidyl amine type epoxy compound derived from an amine having a plurality of active hydrogens, and a polycarboxylic acid. And an epoxy compound obtained by oxidizing a compound having a plurality of double bonds in the molecule.

  Examples of the glycidyl ether type epoxy compound include a glycidyl ether type epoxy compound obtained by a reaction between a polyol and epichlorohydrin. For example, bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetrabromobisphenol A, phenol novolac, cresol novolac, hydroquinone, resorcinol, 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbiphenyl, 1,6-dihydroxynaphthalene, 9,9-bis (4-hydroxyphenyl) fluorene, tris (p-hydroxyphenyl) methane, tetrakis (p-hydroxyphenyl) ethane, neopentyl glycol, 1,6-hexanediol, 1 Glycidyl ether type epoxidation obtained by reaction of at least one selected from the group consisting of 1,4-cyclohexanedimethanol, hydrogenated bisphenol A and hydrogenated bisphenol F with epichlorohydrin Thing, and the like. Examples of the glycidyl ether type epoxy compound include a glycidyl ether type epoxy compound having a biphenylaralkyl skeleton and a glycidyl ether type epoxy compound having a dicyclopentadiene skeleton.

  Examples of the glycidylamine type epoxy compound include N, N-diglycidylaniline, N, N-diglycidyl-o-toluidine, m-xylylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane and 9 , 9-bis (4-aminophenyl) fluorene, 1,3-bis (aminomethyl) cyclohexane, and an epoxy compound obtained by reaction of epichlorohydrin with at least one selected from the group consisting of 1,3-bis (aminomethyl) cyclohexane.

  Further, for example, as a glycidylamine type epoxy compound, both the hydroxyl group and amino group of aminophenols of m-aminophenol, p-aminophenol, and 4-amino-3-methylphenol are reacted with epichlorohydrin. And an epoxy compound obtained.

  Examples of the glycidyl ester type epoxy compound include glycidyl ester type epoxy compounds obtained by reacting phthalic acid, terephthalic acid, hexahydrophthalic acid, and dimer acid with epichlorohydrin.

  Examples of the epoxy compound obtained by oxidizing a compound having a plurality of double bonds in the molecule include an epoxy compound having an epoxycyclohexane ring in the molecule. Furthermore, the epoxy compound includes epoxidized soybean oil.

  As the water-insoluble epoxy compound (B) used in the present invention, in addition to these epoxy compounds, epoxy compounds synthesized from the above-mentioned epoxy compounds, for example, bisphenol A diglycidyl ether and tolylene diisocyanate Examples thereof include an epoxy compound synthesized by an oxazolidone ring formation reaction. Moreover, an epoxy compound such as triglycidyl isocyanurate can be mentioned.

  In the present invention, the water-insoluble epoxy compound (B) is selected from a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, a carboxyl group, an ester group and a sulfo group in addition to one or more epoxy groups. Preferably, at least one functional group is used. For example, compounds having epoxy group and hydroxyl group, compounds having epoxy group and amide group, compounds having epoxy group and imide group, compounds having epoxy group and urethane group, compounds having epoxy group and urea group, epoxy group and sulfonyl Examples thereof include compounds having a group and compounds having an epoxy group and a sulfo group.

  Examples of the water-insoluble epoxy compound (B) having an amide group in addition to the epoxy group include glycidyl benzamide and an amide-modified epoxy compound. The amide-modified epoxy can be obtained by reacting an epoxy group of an epoxy compound having two or more epoxy groups with a carboxyl group of a dicarboxylic acid amide containing an aromatic ring.

  Examples of the water-insoluble epoxy compound (B) having an imide group in addition to the epoxy group include glycidyl phthalimide. Specific examples include “Denacol (registered trademark)” EX-731 (manufactured by Nagase ChemteX Corporation).

  As a water-insoluble epoxy compound (B) having a urethane group in addition to an epoxy group, a polyvalent isocyanate containing an aromatic ring having a reaction equivalent to the amount of the hydroxyl group is reacted with the terminal hydroxyl group of polyethylene oxide monoalkyl ether, It can obtain by making the isocyanate residue of the obtained reaction product react with the hydroxyl group in a polyhydric epoxy compound. Here, examples of the polyvalent isocyanate used include 2,4-tolylene diisocyanate, metaphenylene diisocyanate, paraphenylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, and biphenyl-2,4,4′-triisocyanate. It is done.

  Examples of the water-insoluble epoxy compound (B) having a urea group in addition to the epoxy group include a urea-modified epoxy compound. The urea-modified epoxy can be obtained by reacting the epoxy group of an epoxy compound containing an aromatic ring having two or more epoxy groups with the carboxyl group of the dicarboxylic acid urea.

  Examples of the water-insoluble epoxy compound (B) having a sulfonyl group in addition to the epoxy group include bisphenol S-type epoxy.

  Examples of the water-insoluble epoxy compound (B) having a sulfo group in addition to the epoxy group include glycidyl p-toluenesulfonate and glycidyl 3-nitrobenzenesulfonate.

  In the present invention, the water-insoluble epoxy compound (B) is preferably an aromatic epoxy compound (B1) having one or more aromatic rings in the molecule. The aromatic ring may be an aromatic ring hydrocarbon consisting only of carbon, or a heteroaromatic ring such as furan, thiophene, pyrrole or imidazole containing a heteroatom such as nitrogen or oxygen. The aromatic ring may be a polycyclic aromatic ring such as naphthalene or anthracene. In a carbon fiber reinforced composite material composed of a carbon fiber coated with a sizing agent and a matrix resin, a so-called interface layer in the vicinity of the carbon fiber is affected by the carbon fiber or the sizing agent and may have different characteristics from the matrix resin. . When the sizing agent contains an aromatic epoxy compound (B1) having one or more aromatic rings, a rigid interface layer is formed, the stress transmission ability between the carbon fiber and the matrix resin is improved, and the fiber-reinforced composite material Mechanical properties such as 0 ° tensile strength are improved. Moreover, since the interaction with the carbon fiber is weaker than that of the water-soluble epoxy compound (A) due to the hydrophobicity of the aromatic ring, there are many water-soluble epoxy compounds (A) on the carbon fiber side due to the interaction with the carbon fiber. As a result, a large amount of the water-insoluble epoxy compound (B) is present in the outer layer of the sizing layer. As a result, since the water-insoluble epoxy compound (B) suppresses contact between the water-soluble epoxy compound (A) and moisture, the time elapsed when the carbon fiber coated with the sizing agent according to the present invention is stored in a humid environment. The change can be suppressed, which is preferable. By selecting the water-insoluble epoxy compound (B) having two or more aromatic rings, the stability after storing the carbon fiber in a humid environment can be further improved. There is no particular upper limit on the number of aromatic rings, but 10 is sufficient from the viewpoint of suppressing the reaction with the mechanical properties and the matrix resin.

  In the present invention, the aromatic epoxy compound (B1) is a phenol novolac type epoxy compound, a cresol novolac type epoxy compound, a tetraglycidyl diaminodiphenylmethane, a bisphenol A type epoxy compound or a bisphenol F type epoxy compound. From the viewpoints of storage stability and adhesiveness, bisphenol A type epoxy compounds or bisphenol F type epoxy compounds are more preferable.

  Furthermore, the sizing agent used in the present invention may contain one or more components other than the water-soluble epoxy compound (A) and the water-insoluble epoxy compound (B). Improves handleability, scratch resistance and fluff resistance by blending carbon fiber and sizing agent adhesion promoting component, and sizing agent coated carbon fiber to give convergence or flexibility, and impregnation with matrix resin Can be improved. For the purpose of stabilizing the sizing agent, auxiliary components such as a dispersant and a surfactant may be added.

  In addition to the water-soluble epoxy compound (A) and the water-insoluble epoxy compound (B), an ester compound (C) having no epoxy group in the molecule can be added to the sizing agent used in the present invention. The sizing agent concerning this invention can mix | blend 2-35 mass% of ester compounds (C) with respect to the sizing agent whole quantity except a solvent. More preferably, it is 15-30 mass%. By blending the ester compound (C), the convergence is improved, the handleability is improved, and at the same time, the deterioration of physical properties in wet environment storage due to the reaction between moisture in the air and the sizing agent can be suppressed.

  The ester compound (C) may be an aliphatic ester compound having no aromatic ring, or may be an aromatic ester compound having one or more aromatic rings in the molecule. When the aromatic ester compound (C1) is used as the ester compound (C), the handleability of the sizing agent-coated carbon fiber is improved, and at the same time, the aromatic ester compound (C1) has a weak interaction with the carbon fiber. It exists in the outer layer of the resin, and the effect of suppressing deterioration of physical properties in a wet environment is enhanced. In addition to the ester group, the aromatic ester compound (C1) has a functional group other than an epoxy group, such as a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, a carboxyl group, and a sulfo group. You may have. Specifically, as the aromatic ester compound (C1), an ester compound composed of a condensate of an alkylene oxide adduct of bisphenols and an unsaturated dibasic acid is preferably used. The unsaturated dibasic acid includes an acid anhydride lower alkyl ester, and fumaric acid, maleic acid, citraconic acid, itaconic acid and the like are preferably used. As alkylene oxide adducts of bisphenols, ethylene oxide adducts, propylene oxide adducts, butylene oxide adducts of bisphenol are preferably used. Among the condensates, a condensate of fumaric acid or maleic acid and bisphenol A ethylene oxide or / and propylene oxide adduct is preferably used.

  The method for adding alkylene oxide to bisphenols is not limited, and a known method can be used. If necessary, a saturated dibasic acid or a small amount of a monobasic acid can be added to the unsaturated dibasic acid as long as the properties such as adhesiveness are not impaired. Moreover, normal glycol, polyether glycol, and a small amount of polyhydric alcohol, monohydric alcohol, etc. can be added to the alkylene oxide adduct of bisphenol as long as the properties such as adhesiveness are not impaired. A known method can be used as the condensation method of the alkylene oxide adduct of bisphenol and the unsaturated dibasic acid.

  Further, the sizing agent according to the present invention is a tertiary amine compound and / or tertiary amine salt, cation that is a component that promotes adhesion for the purpose of enhancing the adhesion between the carbon fiber and the epoxy compound in the sizing agent component. At least one compound selected from a quaternary ammonium salt having a moiety, a quaternary phosphonium salt, and / or a phosphine compound can be blended. In the sizing agent according to the invention, the compound is preferably blended in an amount of 0.1 to 25% by mass based on the total amount of the sizing agent excluding the solvent. 2-8 mass% is more preferable.

  To the water-soluble epoxy compound (A) and the water-insoluble epoxy compound (B), a tertiary amine compound and / or tertiary amine salt, a quaternary ammonium salt having a cation site, a quaternary phosphonium salt, and / or Or the sizing agent which used together the at least 1 sort (s) of compound selected from a phosphine compound will further improve adhesiveness, when this sizing agent is apply | coated to carbon fiber and it heat-processes on specific conditions. Although the mechanism is not certain, first, after the compound acts on oxygen-containing functional groups such as carboxyl groups and hydroxyl groups of the carbon fiber used in the present invention, the hydrogen ions contained in these functional groups are extracted and anionized. The anionized functional group and the epoxy group contained in the water-soluble epoxy compound (A) or water-insoluble epoxy compound (B) component are considered to undergo a nucleophilic reaction. Thereby, it is presumed that a strong bond between the carbon fiber used in the present invention and the epoxy group in the sizing agent is formed, and the adhesiveness is improved.

  Specific examples of the adhesion promoting component include N-benzylimidazole, 1,8-diazabicyclo [5,4,0] -7-undecene (DBU) and salts thereof, or 1,5-diazabicyclo [4, 3,0] -5-Nonene (DBN) and a salt thereof are preferable, and 1,8-diazabicyclo [5,4,0] -7-undecene (DBU) and a salt thereof, or 1,5- Diazabicyclo [4,3,0] -5-nonene (DBN) and its salts are preferred.

  Specific examples of the DBU salt include DBU phenol salt (U-CAT SA1, manufactured by San Apro Corporation), DBU octylate (U-CAT SA102, manufactured by San Apro Corporation), DBU p-toluene. Sulfonate (U-CAT SA506, manufactured by San Apro Co., Ltd.), DBU formate (U-CAT SA603, manufactured by San Apro Co., Ltd.), DBU orthophthalate (U-CAT SA810), and DBU phenol novolac resin salt (U-CAT SA810, SA831, SA841, SA851, 881, manufactured by San Apro Corporation) and the like.

  In the present invention, as an adhesion promoting component to be blended with the sizing agent, tributylamine or N, N-dimethylbenzylamine, diisopropylethylamine, triisopropylamine, dibutylethanolamine, diethylethanolamine, triisopropanolamine, triethanolamine, N, N-diisopropylethylamine is preferable, and triisopropylamine, dibutylethanolamine, diethylethanolamine, triisopropanolamine, and diisopropylethylamine are particularly preferable.

  In addition to the above, examples of additives such as surfactants include polyalkylene oxides such as polyethylene oxide and polypropylene oxide, higher alcohols, polyhydric alcohols, alkylphenols, and polyalkylenes such as polyethylene oxide and polypropylene oxide in styrenated phenols. Nonionic surfactants such as compounds added with oxides and block copolymers of ethylene oxide and propylene oxide are preferably used. Moreover, you may add a polyester resin, an unsaturated polyester compound, etc. suitably in the range which does not affect the effect of this invention.

  Next, the carbon fiber used in the present invention will be described. Examples of the carbon fiber used in the present invention include polyacrylonitrile (PAN) -based, rayon-based, and pitch-based carbon fibers. Of these, PAN-based carbon fibers having an excellent balance between strength and elastic modulus are preferably used.

  In the carbon fiber according to the present invention, the strand strength of the obtained carbon fiber bundle is preferably 3.5 GPa or more, more preferably 4 GPa or more, and further preferably 5 GPa or more. Moreover, it is preferable that the strand elastic modulus of the obtained carbon fiber bundle is 220 GPa or more, More preferably, it is 240 GPa or more, More preferably, it is 280 GPa or more.

  In the present invention, the strand tensile strength and elastic modulus of the carbon fiber bundle can be determined according to the following procedure in accordance with the resin impregnated strand test method of JIS-R-7608 (2004). As the resin formulation, “Celoxide (registered trademark)” 2021P (manufactured by Daicel Chemical Industries) / 3 boron trifluoride monoethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) / Acetone = 100/3/4 (part by mass) is used. As curing conditions, normal pressure, 130 ° C., and 30 minutes are used. Ten strands of the carbon fiber bundle were measured, and the average value was defined as the strand tensile strength and the strand elastic modulus.

  The carbon fiber used in the present invention preferably has a surface roughness (Ra) of 6.0 to 100 nm. More preferably, it is 15-80 nm, and 30-60 nm is suitable. Carbon fiber with a surface roughness (Ra) of 6.0 to 60 nm has a highly active edge portion on the surface, so the reactivity with the epoxy group of the sizing agent described above is improved and the interfacial adhesion is improved. This is preferable. Moreover, since the carbon fiber whose surface roughness (Ra) is 6.0-100 nm has an unevenness | corrugation on the surface, it can improve interface adhesiveness by the anchor effect of a sizing agent, and is preferable.

The average roughness (Ra) of the carbon fiber surface can be measured by using an atomic force microscope (AFM). For example, a carbon fiber cut to several millimeters in length is prepared, fixed on a substrate (silicon wafer) using a silver paste, and 3 atomic fibers at the center of each single fiber by an atomic force microscope (AFM). What is necessary is just to observe the image of a three-dimensional surface shape. As an atomic force microscope, a Dimension 3000 stage system or the like can be used in NanoScope IIIa manufactured by Digital Instruments and can be observed under the following observation conditions.
・ Scanning mode: Tapping mode ・ Probe: Silicon cantilever ・ Scanning range: 0.6μm × 0.6μm
・ Scanning speed: 0.3Hz
-Number of pixels: 512 × 512
・ Measurement environment: Room temperature, in the atmosphere For each sample, the image obtained by observing one single fiber at a time, approximating the roundness of the fiber cross section with a cubic surface, and the entire image obtained It is preferable to calculate the average roughness (Ra), obtain the average roughness (Ra) for five single fibers, and evaluate the average value.

  In the present invention, the fine density of the carbon fibers is preferably 400 to 3000 tex. Moreover, the number of filaments of carbon fiber is preferably 1000 to 100,000, and more preferably 3000 to 50000.

  In the present invention, the single fiber diameter of the carbon fiber is preferably 4.5 to 7.5 μm. Since it is 7.5 micrometers or less, since a carbon fiber with high intensity | strength and elastic modulus can be obtained, it is used preferably. More preferably, it is 6 μm or less, and further preferably 5.5 μm or less. When the thickness is 4.5 μm or more, it is difficult to cause single fiber cutting in the process, and productivity is hardly lowered.

  In the present invention, the carbon fiber has a surface oxygen concentration (O / C), which is a ratio of the number of atoms of oxygen (O) and carbon (C) on the fiber surface measured by X-ray photoelectron spectroscopy. The thing within the range of 05-0.50 is preferable, More preferably, it is a thing within the range of 0.06-0.30, More preferably, it is a thing within the range of 0.07-0.25. When the surface oxygen concentration (O / C) is 0.05 or more, an oxygen-containing functional group on the surface of the carbon fiber can be secured and strong adhesion with the matrix resin can be obtained. Moreover, when the surface oxygen concentration (O / C) is 0.50 or less, a decrease in strength of the carbon fiber itself due to oxidation can be suppressed.

The surface oxygen concentration of the carbon fiber is determined by X-ray photoelectron spectroscopy according to the following procedure. First, carbon fibers from which dirt and the like adhering to the carbon fiber surface were removed with a solvent were cut to 20 mm, spread and arranged on a copper sample support base, and then AlKα ₁ and ₂ were used as an X-ray source. The inside of the chamber was measured at 1 × 10 ⁻⁸ Torr. Measurement was performed at a photoelectron escape angle of 90 °. As a correction value for the peak accompanying charging during measurement, the binding energy value of the C _1s main peak (peak top) is adjusted to 284.6 eV. The C _1s peak area is obtained by drawing a straight base line in the range of 282 to 296 eV, and the O _1s peak area is obtained by drawing a straight base line in the range of 528 to 540 eV. The surface oxygen concentration (O / C) is represented by an atomic ratio calculated by dividing the ratio of the O _1s peak area by the sensitivity correction value unique to the apparatus. When ESCA-1600 manufactured by ULVAC-PHI Co., Ltd. is used as the X-ray photoelectron spectroscopy apparatus, the sensitivity correction value unique to the apparatus is 2.33.

  The carbon fiber used in the present invention has a surface carboxyl group concentration (COOH / C) represented by the ratio of the number of carbon group (COOH) and carbon (C) atoms measured by chemical modification X-ray photoelectron spectroscopy. ) Is preferably in the range of 0.003 to 0.015. A more preferable range of the carboxyl group concentration (COOH / C) on the carbon fiber surface is 0.004 to 0.010. The carbon fiber used in the present invention has a surface hydroxyl group concentration (COH / C) expressed by the ratio of the number of hydroxyl groups (OH) and carbon (C) on the surface of the carbon fiber measured by chemical modification X-ray photoelectron spectroscopy. ) Is preferably in the range of 0.001 to 0.050. The surface hydroxyl group concentration (COH / C) on the carbon fiber surface is more preferably in the range of 0.010 to 0.040.

  The surface carboxyl group concentration (COOH / C) and hydroxyl group concentration (COH / C) of the carbon fiber are determined by X-ray photoelectron spectroscopy according to the following procedure.

The surface hydroxyl group concentration (COH / C) is determined by chemical modification X-ray photoelectron spectroscopy according to the following procedure. First, carbon fiber bundles from which the sizing agent and the like have been removed with a solvent are cut, spread and arranged on a platinum sample support, and placed in dry nitrogen gas containing 0.04 mol / liter of anhydrous trifluoride acetic acid gas. After 10 minutes of exposure at room temperature and chemical modification treatment, it was mounted on an X-ray photoelectron spectrometer with a photoelectron escape angle of 35 °, AlKα ₁ , ₂ was used as the X-ray source, and the inside of the sample chamber was 1 × 10 ⁻⁸ Torr. Keep the degree of vacuum. As correction of the peak accompanying charging during measurement, first, the binding energy value of the main peak of C _1s is adjusted to 284.6 eV. The C _1s peak area [C _1s ] is obtained by drawing a straight base line in the range of 282 to 296 eV, and the F _1s peak area [F _1s ] is obtained by drawing a straight base line in the range of 682 to 695 eV. Desired. Moreover, reaction rate r is calculated | required from _C1s peak division _| segmentation of the polyvinyl alcohol chemically modified simultaneously.

  The surface hydroxyl group concentration (COH / C) is represented by a value calculated by the following equation.

COH / C = {[F _1s ] / (3k [C _1s ] −2 [F _1s ]) r} × 100 (%)
Note that k is the sensitivity correction value of the F _1s peak area with respect to the C _1s peak area unique to the apparatus, and when using the model SSX-100-206 manufactured by SSI of the United States, the sensitivity correction value specific to the apparatus is 3.919. .

The surface carboxyl group concentration (COOH / C) is determined by chemical modification X-ray photoelectron spectroscopy according to the following procedure. First, carbon fiber bundles from which the sizing agent and the like have been removed with a solvent are cut and spread and arranged on a platinum sample support, and 0.02 mol / liter of trifluorinated ethanol gas, 0.001 mol / liter of dicyclohexyl. The sample was exposed to air containing carbodiimide gas and 0.04 mol / liter pyridine gas at 60 ° C for 8 hours, chemically modified, mounted on an X-ray photoelectron spectrometer with a photoelectron escape angle of 35 °, and used as an X-ray source. Using AlKα ₁ and ₂ , the inside of the sample chamber is kept at a vacuum of 1 × 10 ⁻⁸ Torr. As correction of the peak accompanying charging during measurement, first, the binding energy value of the main peak of C _1s is adjusted to 284.6 eV. The C _1s peak area [C _1s ] is obtained by drawing a straight base line in the range of 282 to 296 eV, and the F _1s peak area [F _1s ] is obtained by drawing a straight base line in the range of 682 to 695 eV. Desired. Simultaneously, the reaction rate r is determined from the C _1s peak splitting of the polyacrylic acid chemically modified, and the residual rate m of the dicyclohexylcarbodiimide derivative is determined from the O _1s peak splitting.

  The surface carboxyl group concentration COOH / C was represented by the value calculated by the following formula.

COOH / C = {[F _1s ] / (3k [C _1s ] − (2 + 13 m) [F _1s ]) r} × 100 (%)
Note that k is the sensitivity correction value of the F _1s peak area with respect to the C _1s peak area unique to the apparatus, and the sensitivity correction value specific to the apparatus when using the model SSX-100-206 manufactured by SSI of the United States is 3.919. is there.

  Next, a method for producing a PAN-based carbon fiber will be described.

  As a spinning method for obtaining a carbon fiber precursor fiber, spinning methods such as wet, dry, and dry-wet can be used. From the viewpoint of easily obtaining high-strength carbon fibers, it is preferable to use a wet or dry wet spinning method. In particular, the use of a dry and wet spinning method is more preferable because carbon fibers having high strength can be obtained.

  In order to further improve the adhesion between the carbon fiber and the matrix resin, a carbon fiber having a surface roughness (Ra) of 6.0 to 100 nm is preferable. In order to obtain a carbon fiber having the surface roughness, a wet spinning method is used. Preferably, the precursor fiber is spun by.

  As the spinning dope, a solution obtained by dissolving a homopolymer or copolymer of polyacrylonitrile in a solvent can be used. As the solvent, an organic solvent such as dimethyl sulfoxide, dimethylformamide, or dimethylacetamide, or an aqueous solution of an inorganic compound such as nitric acid, sodium rhodanate, zinc chloride, or sodium thiocyanate is used. Dimethyl sulfoxide and dimethylacetamide are suitable as the solvent.

  The above spinning solution is spun through a die, discharged in a spinning bath or in the air, and then coagulated in the spinning bath. As the spinning bath, an aqueous solution of a solvent used as a solvent for the spinning dope can be used. It is preferable to use a spinning solution containing the same solvent as the spinning solution, and a dimethyl sulfoxide aqueous solution and a dimethylacetamide aqueous solution are preferable. The fiber solidified in the spinning bath is washed with water and drawn to obtain a precursor fiber. The obtained precursor fiber is subjected to flameproofing treatment and carbonization treatment, and if necessary, further subjected to graphitization treatment to obtain carbon fiber. As conditions for carbonization treatment and graphitization treatment, the maximum heat treatment temperature is preferably 1100 ° C. or higher, more preferably 1400 to 3000 ° C.

  The obtained carbon fiber is usually subjected to an oxidation treatment in order to improve the adhesiveness with the matrix resin, whereby oxygen-containing functional groups are introduced. As the oxidation treatment method, vapor phase oxidation, liquid phase oxidation, and liquid phase electrolytic oxidation are used. From the viewpoint of high productivity and uniform treatment, liquid phase electrolytic oxidation is preferably used.

  In the present invention, examples of the electrolytic solution used in the liquid phase electrolytic oxidation include an acidic electrolytic solution and an alkaline electrolytic solution. From the viewpoint of adhesion, a liquid phase electrolytic oxidation is performed in an alkaline electrolytic solution, and then a sizing agent is applied. It is more preferable.

  Examples of the acidic electrolyte include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, boric acid, and carbonic acid, organic acids such as acetic acid, butyric acid, oxalic acid, acrylic acid, and maleic acid, or ammonium sulfate and ammonium hydrogen sulfate. And the like. Of these, sulfuric acid and nitric acid exhibiting strong acidity are preferably used.

  Specific examples of the alkaline electrolyte include aqueous solutions of hydroxides such as sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide and barium hydroxide, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, Aqueous solutions of carbonates such as barium carbonate and ammonium carbonate, aqueous solutions of bicarbonates such as sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate, calcium bicarbonate, barium bicarbonate and ammonium bicarbonate, ammonia, tetraalkylammonium hydroxide And an aqueous solution of hydrazine. Among these, from the viewpoint of not containing an alkali metal that causes curing inhibition of the matrix resin, an aqueous solution of ammonium carbonate and ammonium hydrogen carbonate or an aqueous solution of tetraalkylammonium hydroxide exhibiting strong alkalinity is preferably used.

  The concentration of the electrolytic solution used in the present invention is preferably in the range of 0.01 to 5 mol / L, more preferably in the range of 0.1 to 1 mol / L. When the concentration of the electrolytic solution is 0.01 mol / L or more, the electrolytic treatment voltage is lowered, which is advantageous in terms of operating cost. On the other hand, when the concentration of the electrolytic solution is 5 mol / L or less, it is advantageous from the viewpoint of safety.

  The temperature of the electrolytic solution used in the present invention is preferably in the range of 10 to 100 ° C, more preferably in the range of 10 to 40 ° C. When the temperature of the electrolytic solution is 10 ° C. or higher, the efficiency of the electrolytic treatment is improved, which is advantageous in terms of operating cost. On the other hand, when the temperature of the electrolytic solution is less than 100 ° C., it is advantageous from the viewpoint of safety.

  In the present invention, the amount of electricity in the liquid phase electrolytic oxidation is preferably optimized in accordance with the carbonization degree of the carbon fiber, and a larger amount of electricity is required when processing the carbon fiber having a high elastic modulus.

In the present invention, the current density in the liquid phase electrolytic oxidation is preferably in the range of 1.5 to 1000 amperes / m ² per 1 m ² of the surface area of the carbon fiber in the electrolytic treatment solution, more preferably 3 to 500 amperes. / M ² within the range. When the current density is 1.5 amperes / m ² or more, the efficiency of the electrolytic treatment is improved, which is advantageous in terms of operating cost. On the other hand, when the current density is 1000 amperes / m ² or less, it is advantageous from the viewpoint of safety.

  In the present invention, it is preferable to wash and dry the carbon fiber after the electrolytic treatment. As a cleaning method, for example, a dip method or a spray method can be used. Especially, it is preferable to use a dip method from a viewpoint that washing | cleaning is easy, Furthermore, it is a preferable aspect to use a dip method, vibrating a carbon fiber with an ultrasonic wave. Also, if the drying temperature is too high, the functional groups present on the outermost surface of the carbon fiber are likely to disappear due to thermal decomposition, so it is desirable to dry at the lowest possible temperature. Specifically, the drying temperature is preferably 250 ° C. or lower. More preferably, drying is performed at 210 ° C. or lower. On the other hand, considering the efficiency of drying, the drying temperature is preferably 110 ° C. or higher, and more preferably 140 ° C. or higher.

  Next, the manufacturing method of the sizing agent application | coating carbon fiber which apply | coated the sizing agent to the carbon fiber mentioned above is demonstrated. The sizing agent according to the present invention contains at least the water-soluble epoxy compound (A) and the water-insoluble epoxy compound (B), and may contain other components.

  In the present invention, the sizing agent is applied to the carbon fiber by a sizing agent-containing liquid in which a water-soluble epoxy compound (A), a water-insoluble epoxy compound (B), and other components are simultaneously dissolved or dispersed in a solvent. Using a sizing agent-containing solution in which each compound (A), (B) and other components are arbitrarily selected and individually dissolved or dispersed in a solvent, and carbon fiber is used multiple times. The method of applying to is preferably used. In the present invention, it is more preferable to adopt a one-step application in which a sizing agent-containing liquid containing all components of the sizing agent is applied to carbon fibers at a time from the standpoint of effect and ease of processing.

  The sizing agent according to the present invention can be used as a sizing agent-containing liquid obtained by diluting a sizing agent component with a solvent. Examples of such a solvent include water, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, dimethylformamide, and dimethylacetamide. Among them, handling is easy and advantageous from the viewpoint of safety. Therefore, an aqueous dispersion or aqueous solution emulsified with a surfactant is preferably used.

  In the sizing agent-containing liquid in the present invention, a water emulsion liquid is prepared by emulsifying a component containing at least the water-insoluble epoxy compound (B) with a surfactant, and a solution containing at least the water-soluble epoxy compound (A) is mixed. It is preferable to make adjustments. At this time, the water-soluble epoxy compound (A) is dissolved in water in advance to make an aqueous solution of 0.1 to 50% by mass, and the water-insoluble epoxy compound (B) having a concentration of 0.1 to 50% by mass. From the viewpoint of emulsion stability, a method of mixing with an aqueous emulsion liquid containing at least the above-mentioned is preferable. In addition, it is preferable to use an aqueous dispersant obtained by emulsifying a water-soluble epoxy compound (A), a water-insoluble epoxy compound (B) and other components with a surfactant from the viewpoint of long-term stability of the sizing agent. it can.

  The concentration of the sizing agent in the sizing agent-containing liquid is usually preferably in the range of 0.2% by mass to 20% by mass.

  The sizing agent-containing liquid in the present invention, and the water-based emulsion containing at least the water-insoluble epoxy compound (B) preferably has a particle size of 100 to 600 nanometers as measured by a particle size distribution meter. More preferably, it is 500 nanometers or less, More preferably, it is the range of 300 nanometers or less. Within the above range, the dispersibility in water is good, and the long-term stability of the sizing agent is improved. Further, the sizing agent can be uniformly applied when the sizing agent is applied to the carbon fibers.

  Examples of the means for applying (coating) the sizing agent to the carbon fiber include a method of immersing the carbon fiber in a sizing agent-containing liquid through a roller, a method of contacting the carbon fiber with a roller to which the sizing agent-containing liquid is attached, and a sizing agent. There is a method of spraying the liquid on the carbon fiber in the form of a mist. Further, the sizing agent applying means may be either a batch type or a continuous type, but a continuous type capable of improving productivity and reducing variation is preferably used. At this time, it is preferable to control the concentration of the sizing agent-containing liquid, the temperature, the yarn tension, and the like so that the amount of the sizing agent active component attached to the carbon fiber is uniformly attached within an appropriate range. Moreover, it is also a preferable aspect that the carbon fiber is vibrated with ultrasonic waves when the sizing agent is applied.

  The liquid temperature of the sizing agent-containing liquid when the sizing agent-containing liquid is applied to the carbon fiber is preferably in the range of 10 to 50 ° C. in order to suppress the concentration fluctuation of the sizing agent due to solvent evaporation. In addition, after applying the sizing agent-containing liquid, the amount of sizing agent adhered can be adjusted and uniformly applied to the carbon fiber by adjusting the amount of squeezing out the excess sizing agent-containing liquid.

  After applying the sizing agent to the carbon fiber, it is preferable to heat-treat in the temperature range of 160 to 260 ° C. for 30 to 600 seconds. The heat treatment conditions are preferably in a temperature range of 170 to 250 ° C. for 30 to 500 seconds, and more preferably in a temperature range of 180 to 240 ° C. for 30 to 300 seconds. When the heat treatment condition is less than 160 ° C. and / or less than 30 seconds, the interaction between the water-soluble epoxy compound (A) of the sizing agent and the oxygen-containing functional group on the surface of the carbon fiber is not promoted, and the carbon fiber Adhesiveness with the matrix resin becomes insufficient, and the solvent may not be sufficiently removed by drying. On the other hand, when the heat treatment condition exceeds 260 ° C. and / or exceeds 600 seconds, decomposition and volatilization of the sizing agent occurs, the interaction with the carbon fiber is not promoted, and the adhesion between the carbon fiber and the matrix resin is increased. It may be insufficient.

  The heat treatment can also be performed by microwave irradiation and / or infrared irradiation. When the sizing agent-coated carbon fiber is heat-treated by microwave irradiation and / or infrared irradiation, the microwave penetrates into the carbon fiber and is absorbed, so that the carbon fiber which is the object to be heated can be heated to a desired temperature in a short time. Can be heated. In addition, since the inside of the carbon fiber can be quickly heated by microwave irradiation and / or infrared irradiation, the temperature difference between the inside and outside of the carbon fiber bundle can be reduced, and the adhesion unevenness of the sizing agent can be reduced. It becomes possible to do.

  The sizing agent-coated carbon fiber of the present invention is used in the form of, for example, tow, woven fabric, knitted fabric, braided string, web, mat, and chopped. In particular, for applications that require high specific strength and high specific modulus, a tow in which carbon fibers are aligned in one direction is most suitable, and a prepreg impregnated with a matrix resin is preferably used.

  Next, details of the prepreg and the carbon fiber reinforced composite material using the sizing agent-coated carbon fiber of the present invention will be described.

  As the matrix resin, a thermosetting resin or a thermoplastic resin (the resin described here may be a resin composition) can be used.

  The thermosetting resin used in the present invention is not particularly limited as long as the crosslinking reaction proceeds by heat and at least partially forms a three-dimensional crosslinked structure. Examples of such thermosetting resins include epoxy resins, unsaturated polyester resins, vinyl ester resins, benzoxazine resins, phenol resins, urea resins, melamine resins, thermosetting polyimide resins, and the like. Two or more types of blended resins can also be used. In addition, these thermosetting resins may be self-curing by heating, or may be blended with a curing agent or a curing accelerator.

  The epoxy compound (D) used for the epoxy resin is not particularly limited, and is a bisphenol type epoxy compound, an amine type epoxy compound, a phenol novolac type epoxy compound, a cresol novolac type epoxy compound, a resorcinol type epoxy compound, a phenol aralkyl type. Select one or more of epoxy compounds, naphthol aralkyl type epoxy compounds, dicyclopentadiene type epoxy compounds, epoxy compounds having a biphenyl skeleton, isocyanate-modified epoxy compounds, tetraphenylethane type epoxy compounds, triphenylmethane type epoxy compounds, etc. Can be used.

  Here, the bisphenol type epoxy compound is obtained by glycidylation of two phenolic hydroxyl groups of a bisphenol compound. The bisphenol A type, the bisphenol F type, the bisphenol AD type, the bisphenol S type, or the halogen or alkyl of these bisphenols. Examples include substituted products and hydrogenated products. Moreover, not only a monomer but the high molecular weight body which has several repeating units can also be used conveniently.

  Commercially available bisphenol A type epoxy compounds include “jER (registered trademark)” 825, 828, 834, 1001, 1002, 1003, 1003F, 1004, 1004AF, 1005F, 1006FS, 1007, 1009, 1010 (and above, Mitsubishi Chemical) Etc.). Examples of the brominated bisphenol A type epoxy compound include “jER (registered trademark)” 505, 5050, 5051, 5054, 5057 (manufactured by Mitsubishi Chemical Corporation). Examples of commercially available hydrogenated bisphenol A type epoxy compounds include ST5080, ST4000D, ST4100D, and ST5100 (manufactured by Nippon Steel Chemical Co., Ltd.).

  Commercially available bisphenol F type epoxy compounds include “jER (registered trademark)” 806, 807, 4002P, 4004P, 4007P, 4009P, 4010P (above, manufactured by Mitsubishi Chemical Corporation), “Epiclon (registered trademark)” 830. 835 (above, manufactured by DIC Corporation), “Epototo (registered trademark)” YDF2001, YDF2004 (above, manufactured by Nippon Steel Chemical Co., Ltd.), and the like. Examples of the tetramethylbisphenol F type epoxy compound include YSLV-80XY (manufactured by Nippon Steel Chemical Co., Ltd.).

  Examples of the bisphenol S-type epoxy compound include “Epiclon (registered trademark)” EXA-154 (manufactured by DIC Corporation).

  Examples of the amine-type epoxy compound include tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, triglycidylaminocresol, tetraglycidylxylylenediamine, halogens thereof, alkynol-substituted products, and hydrogenated products.

  Commercially available products of tetraglycidyldiaminodiphenylmethane include “Sumiepoxy (registered trademark)” ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), YH434L (manufactured by Nippon Steel Chemical Co., Ltd.), and “jER (registered trademark)” 604 (Mitsubishi Chemical). (Manufactured by Co., Ltd.), “Araldide (registered trademark)” MY720, MY721 (manufactured by Huntsman Advanced Materials Co., Ltd.), and the like. Commercially available products of triglycidylaminophenol or triglycidylaminocresol include “Sumiepoxy (registered trademark)” ELM100, ELM120 (manufactured by Sumitomo Chemical Co., Ltd.), “Araldide (registered trademark)” MY0500, MY0510, MY0600 (and above) , Huntsman Advanced Materials Co., Ltd.), “jER (registered trademark)” 630 (manufactured by Mitsubishi Chemical Corporation), and the like. Examples of commercially available tetraglycidylxylylenediamine and hydrogenated products thereof include TETRAD-X and TETRAD-C (manufactured by Mitsubishi Gas Chemical Co., Ltd.).

  Commercially available products of phenol novolac type epoxy compounds are “jER (registered trademark)” 152, 154 (manufactured by Mitsubishi Chemical Corporation), “Epicron (registered trademark)” N-740, N-770, N-775 ( As mentioned above, DIC Corporation) etc. are mentioned.

  As a commercial item of a cresol novolac type epoxy compound, “Epiclon (registered trademark)” N-660, N-665, N-670, N-673, N-695 (above, manufactured by DIC Corporation), EOCN-1020 , EOCN-102S, EOCN-104S (manufactured by Nippon Kayaku Co., Ltd.), and the like.

  Examples of commercially available resorcinol-type epoxy compounds include “Denacol (registered trademark)” EX-201 (manufactured by Nagase ChemteX Corporation).

  Examples of commercially available glycidyl aniline type epoxy compounds include GAN and GOT (manufactured by Nippon Kayaku Co., Ltd.).

  Examples of commercially available epoxy compounds having a biphenyl skeleton include “jER (registered trademark)” YX4000H, YX4000, YL6616 (manufactured by Mitsubishi Chemical Corporation), NC-3000 (manufactured by Nippon Kayaku Co., Ltd.), and the like. It is done.

  Commercially available dicyclopentadiene type epoxy compounds include “Epiclon (registered trademark)” HP7200L (epoxy value 4.00, softening point 54 to 58), “Epiclon (registered trademark)” HP7200 (epoxy value 3.84, softening) 59-63), "Epiclon (registered trademark)" HP7200H (epoxy value 3.57, softening point 80-85), "Epiclon (registered trademark)" HP7200HH (epoxy value 3.57, softening point 87-92) ( As described above, manufactured by Dainippon Ink & Chemicals, Inc.), XD-1000-L (epoxy value 3.92, softening point 60 to 70), XD-1000-2L (epoxy value 4.00, softening point 53 to 63) (Nippon Kayaku Co., Ltd.), “Tactix (registered trademark)” 556 (epoxy value 4.25, softening point 79 ° C.) (manufactured by Vantico Inc.) And the like.

  Examples of commercially available isocyanate-modified epoxy compounds include XAC4151, AER4152 (produced by Asahi Kasei Epoxy Co., Ltd.) and ACR1348 (produced by ADEKA Co., Ltd.) having an oxazolidone ring.

  Examples of commercially available tetraphenylethane type epoxy compounds include “jER (registered trademark)” 1031 (manufactured by Mitsubishi Chemical Corporation), which is a tetrakis (glycidyloxyphenyl) ethane type epoxy compound.

  As a commercial item of a triphenylmethane type epoxy compound, “Tactics (registered trademark)” 742 (manufactured by Huntsman Advanced Materials Co., Ltd.) and the like can be mentioned.

  As unsaturated polyester resin, what melt | dissolved the unsaturated polyester obtained by making the acid component and alcohol which contain (alpha), (beta) -unsaturated dicarboxylic acid react in a polymerizable unsaturated monomer is mentioned. Examples of the α, β-unsaturated dicarboxylic acid include maleic acid, fumaric acid, itaconic acid and the like, derivatives of these acid anhydrides and the like, and these may be used in combination of two or more. In addition, as necessary, as acid components other than α, β-unsaturated dicarboxylic acids, saturated dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, adipic acid, sebacic acid, and acid anhydrides thereof, etc. The derivative may be used in combination with an α, β-unsaturated dicarboxylic acid.

  Examples of the alcohol include aliphatic glycols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol, cyclohexane Alicyclic diols such as pentanediol and cyclohexanediol, hydrogenated bisphenol A, bisphenol A propylene oxide (1 to 100 mol) adducts, aromatic diols such as xylene glycol, polyhydric alcohols such as trimethylolpropane and pentaerythritol, etc. These may be used in combination of two or more thereof.

  Specific examples of the unsaturated polyester resin include, for example, a condensate of fumaric acid or maleic acid and bisphenol A ethylene oxide (hereinafter abbreviated as EO) adduct, fumaric acid or maleic acid and bisphenol A propylene oxide (hereinafter referred to as “unsaturated polyester resin”). And abbreviated as PO.) Condensates with adducts and fumaric acid or maleic acid with EO and PO adducts of bisphenol A (addition of EO and PO may be random or block), etc. These condensates may be dissolved in a monomer such as styrene as necessary. Commercially available unsaturated polyester resins include “Yupika (registered trademark)” (manufactured by Nippon Yupica), “Rigolac (registered trademark)” (manufactured by Showa Denko), “Polyset (registered trademark)” (Manufactured by Hitachi Chemical Co., Ltd.).

  Examples of the vinyl ester resin include epoxy (meth) acrylate obtained by esterifying the epoxy compound and an α, β-unsaturated monocarboxylic acid. Examples of the α, β-unsaturated monocarboxylic acid include acrylic acid, methacrylic acid, crotonic acid, tiglic acid and cinnamic acid, and two or more of these may be used in combination. Specific examples of the vinyl ester resin include, for example, a modified bisphenol type epoxy compound (meth) acrylate (terminal (meth) obtained by reacting an epoxy group of a bisphenol A type epoxy compound and a carboxyl group of (meth) acrylic acid). Acrylate-modified resins and the like), and these modified products may be dissolved in a monomer such as styrene as necessary. Commercially available vinyl ester resins include “Dicklight (registered trademark)” (manufactured by DIC Corporation), “Neopol (registered trademark)” (manufactured by Nippon Yupica Corporation), “Lipoxy (registered trademark)” (Showa) Polymer Co., Ltd.).

  Examples of the benzoxazine resin include o-cresol aniline type benzoxazine resin, m-cresol aniline type benzoxazine resin, p-cresol aniline type benzoxazine resin, phenol-aniline type benzoxazine resin, phenol-methylamine type benzoxazine resin, Phenol-cyclohexylamine type benzoxazine resin, phenol-m-toluidine type benzoxazine resin, phenol-3,5-dimethylaniline type benzoxazine resin, bisphenol A-aniline type benzoxazine resin, bisphenol A-amine type benzoxazine resin, Bisphenol F-aniline type benzoxazine resin, bisphenol S-aniline type benzoxazine resin, dihydroxydiphenylsulfone-aniline type Nzooxazine resin, dihydroxydiphenyl ether-aniline type benzoxazine resin, benzophenone type benzoxazine resin, biphenyl type benzoxazine resin, bisphenol AF-aniline type benzoxazine resin, bisphenol A-methylaniline type benzoxazine resin, phenol-diaminodiphenylmethane type benzoxazine Examples thereof include resins, triphenylmethane type benzoxazine resins, and phenolphthalein type benzoxazine resins. Examples of commercially available benzoxazine resins include BF-BXZ, BS-BXZ, BA-BXZ (manufactured by Konishi Chemical Industry Co., Ltd.).

  Examples of the phenol resin include resins obtained by condensation of phenols such as phenol, cresol, xylenol, t-butylphenol, nonylphenol, cashew oil, lignin, resorcin, and catechol with aldehydes such as formaldehyde, acetaldehyde, and furfural. , Novolak resins and resol resins. The novolak resin can be obtained by reacting phenol and formaldehyde in the same amount or in excess of phenol in the presence of an acid catalyst such as oxalic acid. The resole resin can be obtained by reacting phenol and formaldehyde in the same amount or in excess of formaldehyde in the presence of a base catalyst such as sodium hydroxide, ammonia or organic amine. Commercially available phenolic resins include “Sumilite Resin (registered trademark)” (manufactured by Sumitomo Bakelite Co., Ltd.), Resitop (manufactured by Gunei Chemical Industry Co., Ltd.), “AV Light (registered trademark)” (Asahi Organic Materials) Kogyo Co., Ltd.).

  Examples of the urea resin include a resin obtained by condensation of urea and formaldehyde. Examples of commercially available urea resins include UA-144 (manufactured by Sunbake Co., Ltd.).

  Examples of the melamine resin include a resin obtained by polycondensation of melamine and formaldehyde. Examples of commercially available melamine resins include “Nicalac (registered trademark)” (manufactured by Sanwa Chemical Co., Ltd.).

  The thermosetting polyimide resin includes a resin containing at least one imide ring in the main structure and one or more selected from phenylethynyl group, nadiimide group, maleimide group, acetylene group and the like in the terminal or main chain. It is done. Examples of commercially available polyimide resin include PETI-330 (manufactured by Ube Industries).

  Among these thermosetting resins, it is preferable to use an epoxy resin containing at least an epoxy compound (D) because it has an advantage of excellent balance of mechanical properties and small curing shrinkage. In particular, an epoxy resin containing at least a glycidylamine type epoxy compound having a plurality of functional groups as the epoxy compound (D) is preferable. An epoxy resin containing at least a glycidylamine type epoxy compound having a plurality of functional groups is preferable because it has a high multi-crosslinking density and can improve the heat resistance and compressive strength of the carbon fiber reinforced composite material.

  Examples of the glycidylamine-type epoxy compound having a plurality of functional groups include tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol and triglycidylaminocresol, N, N-diglycidylaniline, N, N-diglycidyl-o-toluidine, N , N-diglycidyl-4-phenoxyaniline, N, N-diglycidyl-4- (4-methylphenoxy) aniline, N, N-diglycidyl-4- (4-tert-butylphenoxy) aniline and N, N-diglycidyl- 4- (4-phenoxyphenoxy) aniline and the like can be mentioned. In many cases, these compounds are obtained by adding epichlorohydrin to a phenoxyaniline derivative and cyclizing with an alkali compound. Since the viscosity increases as the molecular weight increases, N, N-diglycidyl-4-phenoxyaniline is particularly preferably used from the viewpoint of handleability.

  Specific examples of the phenoxyaniline derivative include 4-phenoxyaniline, 4- (4-methylphenoxy) aniline, 4- (3-methylphenoxy) aniline, 4- (2-methylphenoxy) aniline, 4- (4 -Ethylphenoxy) aniline, 4- (3-ethylphenoxy) aniline, 4- (2-ethylphenoxy) aniline, 4- (4-propylphenoxy) aniline, 4- (4-tert-butylphenoxy) aniline, 4- (4-cyclohexylphenoxy) aniline, 4- (3-cyclohexylphenoxy) aniline, 4- (2-cyclohexylphenoxy) aniline, 4- (4-methoxyphenoxy) aniline, 4- (3-methoxyphenoxy) aniline, 4- (2-methoxyphenoxy) aniline, 4- (3-phenoxyf) Noxy) aniline, 4- (4-phenoxyphenoxy) aniline, 4- [4- (trifluoromethyl) phenoxy] aniline, 4- [3- (trifluoromethyl) phenoxy] aniline, 4- [2- (trifluoro) Methyl) phenoxy] aniline, 4- (2-naphthyloxyphenoxy) aniline, 4- (1-naphthyloxyphenoxy) aniline, 4-[(1,1′-biphenyl-4-yl) oxy] aniline, 4- ( 4-nitrophenoxy) aniline, 4- (3-nitrophenoxy) aniline, 4- (2-nitrophenoxy) aniline, 3-nitro-4-aminophenyl phenyl ether, 2-nitro-4- (4-nitrophenoxy) Aniline, 4- (2,4-dinitrophenoxy) aniline, 3-nitro-4-phenoxyaniline, -(2-chlorophenoxy) aniline, 4- (3-chlorophenoxy) aniline, 4- (4-chlorophenoxy) aniline, 4- (2,4-dichlorophenoxy) aniline, 3-chloro-4- (4- Chlorophenoxy) aniline, 4- (4-chloro-3-tolyloxy) aniline, and the like.

  Examples of commercially available products of tetraglycidyldiaminodiphenylmethane include “Sumiepoxy (registered trademark)” ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), YH434L (manufactured by Tohto Kasei Co., Ltd.), “Araldite (registered trademark)” MY720 (Huntsman Advanced -Materials Co., Ltd.), "jER (registered trademark) 604" (Mitsubishi Chemical Co., Ltd.), etc. can be used. Examples of triglycidylaminophenol and triglycidylaminocresol include, for example, “Sumiepoxy (registered trademark)” ELM100 (manufactured by Sumitomo Chemical Co., Ltd.), “Araldite (registered trademark)” MY0510, “Araldite (registered trademark)” MY0600 (and above) , Huntsman Advanced Materials Co., Ltd.), “jER (registered trademark)” 630 (Mitsubishi Chemical Co., Ltd.), and the like can be used.

  Among the above-mentioned glycidylamine type epoxy compounds having a plurality of functional groups, an aromatic epoxy compound (D1) having at least one glycidylamine skeleton and three or more epoxy groups is preferable.

  The epoxy resin containing the glycidylamine type aromatic epoxy compound (D1) having 3 or more epoxy groups has an effect of improving heat resistance, and the ratio is preferably 30 to 100% by mass in the epoxy resin. A more desirable ratio is 50% by mass or more. The ratio of the glycidylamine type aromatic epoxy compound is preferably 30% by mass or more, since the compressive strength of the carbon fiber reinforced composite material is improved and the heat resistance is improved.

  When using these epoxy compounds (D), you may add catalysts and hardening | curing agents, such as an acid and a base, as needed. For example, for curing epoxy resins, Lewis acids such as boron halide complexes and p-toluenesulfonate, and polyamine curing agents such as diaminodiphenylsulfone, diaminodiphenylmethane and their derivatives and isomers are preferably used.

  In the prepreg using the sizing agent-coated carbon fiber of the present invention, the latent curing agent (E) can be used as the curing agent. The latent curing agent described here is a curing agent for the thermosetting resin of the present invention, which is a curing agent that is activated by applying a temperature and reacts with a reactive group such as an epoxy group, and is 70 ° C. or higher. It is preferable that the reaction is activated. Here, activation at 70 ° C. means that the reaction start temperature is in the range of 70 ° C. Such reaction start temperature (hereinafter referred to as activation temperature) can be determined by, for example, differential scanning calorimetry (DSC). Specifically, for an epoxy resin composition obtained by adding 10 parts by mass of a curing agent to be evaluated to 100 parts by mass of a bisphenol A type epoxy compound having an epoxy value of about 5.15, an inflection of an exothermic curve obtained by differential scanning calorimetry. It is obtained from the intersection of the point tangent and the baseline tangent.

  The latent curing agent (E) is preferably an aromatic amine curing agent (E1), or dicyandiamide or a derivative thereof (E2). The aromatic amine curing agent (E1) is not particularly limited as long as it is an aromatic amine used as an epoxy resin curing agent. Specifically, 3,3′-diaminodiphenyl sulfone (3,3) is used. 3'-DDS), 4,4'-diaminodiphenylsulfone (4,4'-DDS), diaminodiphenylmethane (DDM), 3,3'-diisopropyl-4,4'-diaminodiphenylmethane, 3,3'-di -T-butyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diisopropyl-5,5'-dimethyl-4 , 4′-diaminodiphenylmethane, 3,3′-di-t-butyl-5,5′-dimethyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5 ′ -Tetraethyl-4,4'-diaminodiphenylmethane, 3,3'-diisopropyl-5,5'-diethyl-4,4'-diaminodiphenylmethane, 3,3'-di-t-butyl-5,5'-diethyl -4,4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetraisopropyl-4,4'-diaminodiphenylmethane, 3,3'-di-t-butyl-5,5'-diisopropyl-4, 4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetra-t-butyl-4,4'-diaminodiphenylmethane, diaminodiphenyl ether (DADPE), bisaniline, benzyldimethylaniline, 2- (dimethylaminomethyl) phenol (DMP-10), 2,4,6-tris (dimethylaminomethyl) phenol (DMP-30), 2 4,6-tris (dimethylaminomethyl) 2-ethylhexanoic acid ester of a phenol or the like can be used. These may be used alone or in admixture of two or more.

  Commercially available aromatic amine curing agents (E1) include Seika Cure S (manufactured by Wakayama Seika Kogyo Co., Ltd.), MDA-220 (manufactured by Mitsui Chemicals, Inc.), “jER Cure (registered trademark)” W (Japan) Epoxy Resin Co., Ltd.), and 3,3′-DAS (Mitsui Chemicals Co., Ltd.), Lonzacure® M-DEA (Lonza Co., Ltd.), “Lonzacure®” M-DIPA (Lonza Co., Ltd.), “Lonzacure (registered trademark)” M-MIPA (Lonza Co., Ltd.), “Lonzacure (registered trademark)” DETDA 80 (Lonza Co., Ltd.), and the like.

  The dicyandiamide derivative or its derivative (E2) is a compound reacted with at least one of an amino group, an imino group and a cyano group. For example, o-tolylbiguanide, diphenylbiguanide, dicyandiamide amino group, imino A group or a cyano group is pre-reacted with an epoxy group of an epoxy compound used in an epoxy resin composition.

  As a commercial item of dicyandiamide or its derivative (E2), DICY-7, DICY-15 (above, Japan Epoxy Resin Co., Ltd. product) etc. are mentioned.

  Curing agents other than the aromatic amine curing agent (E1), dicyandiamide or its derivative (E2) include amines such as alicyclic amines, phenolic compounds, acid anhydrides, polyaminoamides, organic acid hydrazides, and isocyanates. You may use together with a hardening | curing agent.

  As the phenol compound used as the latent curing agent (E), the phenol compounds exemplified above as the matrix resin can be arbitrarily used.

  As a combination of the sizing agent according to the present invention and the aromatic amine curing agent (E1), the following combinations are preferable. The sizing agent and aromatic amine curing agent (E1) were mixed at a ratio of amine equivalent / epoxy equivalent of 0.9 of the amine equivalent and epoxy equivalent of the sizing agent and aromatic amine curing agent (E1) to be applied. The glass transition point is measured immediately after mixing and when stored for 20 days in an environment of a temperature of 25 ° C. and a humidity of 60%. A combination of a sizing agent having an increase in glass transition point after lapse of 20 days of 25 ° C. or less and an aromatic amine curing agent (E1) is preferable. When the glass transition point rises to 25 ° C. or lower, the reaction in the sizing agent outer layer and the matrix resin is suppressed when the prepreg is formed, and the tensile strength of the carbon fiber reinforced composite material after the prepreg is stored for a long period of time. This is preferable because a decrease in the mechanical properties of is suppressed. Moreover, it is more preferable that the increase in the glass transition point is 15 ° C. or less. More preferably, it is 10 ° C. or lower. The glass transition point can be determined by differential scanning calorimetry (DSC).

  Moreover, as a combination of the sizing agent according to the present invention and dicyandiamide (E2), the following combinations are preferable. The sizing agent and dicyandiamide (E2) are mixed at a ratio of amine equivalent / epoxy equivalent of 1.0 and the amine equivalent / epoxy equivalent is 1.0, and the sizing agent and dicyandiamide (E2) are mixed. The glass transition point when stored for 20 days in an environment of 60% humidity is measured. A combination of a sizing agent having a glass transition point increase of 10 ° C. or less after 20 days and dicyandiamide (E2) is preferable. When the glass transition point rises to 10 ° C. or less, the reaction in the sizing agent outer layer and the matrix resin is suppressed when the prepreg is formed, and the tensile strength of the carbon fiber reinforced composite material after the prepreg is stored for a long period of time. This is preferable because a decrease in the mechanical properties of is suppressed. Moreover, it is more preferable that the increase in the glass transition point is 8 ° C. or less.

  Moreover, it is preferable that the total amount of a hardening | curing agent contains the quantity from which an active hydrogen group becomes the range of 0.6-1.2 equivalent with respect to 1 equivalent of epoxy groups of all the epoxy resin components, More preferably, 0.7- Including an amount in the range of 0.9 equivalents. Here, the active hydrogen group means a functional group that can react with the epoxy group of the curing agent component, and when the active hydrogen group is less than 0.6 equivalent, the reaction rate, heat resistance, and elastic modulus of the cured product. In some cases, the glass transition temperature and strength of the fiber reinforced composite material may be insufficient. If the active hydrogen group exceeds 1.2 equivalents, the reaction rate, glass transition temperature, and elastic modulus of the cured product are sufficient, but the plastic deformation ability is insufficient, so the impact resistance of the carbon fiber reinforced composite material May be insufficient.

  Moreover, when a thermosetting resin is an epoxy resin, a hardening accelerator (F) can also be mix | blended in order to accelerate hardening.

  Examples of the curing accelerator (F) include urea compounds, tertiary amines and salts thereof, imidazoles and salts thereof, triphenylphosphine or derivatives thereof, carboxylic acid metal salts, Lewis acids, Bronsted acids and salts thereof, and the like. It is done. Among these, the urea compound (F1) is preferably used from the balance between storage stability and catalytic ability.

  In particular, when the urea compound (F1) is used as the curing accelerator (F), the latent curing agent (E) is preferably used in combination with dicyandiamide or a derivative (E2) thereof.

  Examples of the urea compound (F1) include N, N-dimethyl-N ′-(3,4-dichlorophenyl) urea, toluenebis (dimethylurea), 4,4′-methylenebis (phenyldimethylurea), and 3-phenyl. -1,1-dimethylurea and the like can be used. Examples of commercially available urea compounds include DCMU99 (manufactured by Hodogaya Chemical Co., Ltd.), “Omicure (registered trademark)” 24, 52, 94 (manufactured by Emerald Performance Materials, LLC).

  It is preferable that the compounding quantity of a urea compound (F1) shall be 1-4 mass parts with respect to 100 mass parts of all the epoxy resin components. When the compounding quantity of this urea compound (F1) is less than 1 mass part, reaction may not fully advance and the elasticity modulus and heat resistance of hardened | cured material may be insufficient. Moreover, when the compounding quantity of this urea compound exceeds 4 mass parts, since the self-polymerization reaction of an epoxy compound inhibits reaction with an epoxy compound and a hardening | curing agent, the toughness of hardened | cured material is insufficient, and an elasticity modulus May decrease.

  Moreover, the thing which made these epoxy resin and hardening | curing agent, or some of them pre-react can be mix | blended in a composition. This method may be effective for viscosity adjustment and storage stability improvement.

  In order to adjust toughness and fluidity, the prepreg preferably contains a thermoplastic resin. From the viewpoint of heat resistance, polysulfone, polyethersulfone, polyetherimide, polyimide, polyamide, polyamideimide, polyphenylene More preferably, it contains at least one selected from ethers, phenoxy resins, and polyolefins. Moreover, the oligomer of a thermoplastic resin can be included. Moreover, an elastomer, a filler, and another additive can also be mix | blended. Note that the thermoplastic resin is preferably contained in the thermosetting resin constituting the prepreg. Furthermore, when an epoxy resin is used as the thermosetting resin, as the thermoplastic resin, a thermoplastic resin soluble in the epoxy resin, organic particles such as rubber particles and thermoplastic resin particles, and the like can be blended. As the thermoplastic resin soluble in the epoxy resin, a thermoplastic resin having a hydrogen bonding functional group that can be expected to improve the adhesion between the resin and the carbon fiber is preferably used.

  As the thermoplastic resin soluble in epoxy resin and having a hydrogen bonding functional group, a thermoplastic resin having an alcoholic hydroxyl group, a thermoplastic resin having an amide bond, or a thermoplastic resin having a sulfonyl group can be used.

  Examples of the thermoplastic resin having an alcoholic hydroxyl group include polyvinyl acetal resins such as polyvinyl formal and polyvinyl butyral, polyvinyl alcohol, and phenoxy resins. Examples of the thermoplastic resin having an amide bond include polyamide, polyimide, Polyvinyl pyrrolidone can be mentioned, and as a thermoplastic resin having a sulfonyl group, polysulfone can be mentioned. Polyamide, polyimide and polysulfone may have a functional group such as an ether bond and a carbonyl group in the main chain. The polyamide may have a substituent on the nitrogen atom of the amide group.

  Examples of commercially available thermoplastic resins that are soluble in epoxy resins and have hydrogen-bonding functional groups include, as polyvinyl acetal resins, Denkabutyral (manufactured by Denki Kagaku Kogyo Co., Ltd.), “Vinylec (registered trademark)” (Chisso ( Manufactured by Co., Ltd.), “UCAR (registered trademark)” PKHP (made by Union Carbide Co., Ltd.) as a phenoxy resin, “Macromelt (registered trademark)” (produced by Henkel Hakusui Co., Ltd.), “Amilan (registered) as a polyamide resin Trademark) ”(manufactured by Toray Industries, Inc.),“ Ultem (registered trademark) ”(manufactured by SABIC Innovative Plastics Japan LLC),“ Matrimid (registered trademark) ”5218 (manufactured by Ciba), and“ polysulfone ” "Sumika Excel (registered trademark)" (manufactured by Sumitomo Chemical Co., Ltd.), "UDEL (registered trademark)", RADEL Registered trademark) "(or, Solvay Advanced Polymers Co., Ltd.), as a polyvinylpyrrolidone," Luviskol (registered trademark) "(BASF Japan Ltd. can be exemplified, Ltd.).

  In addition, the acrylic resin has high compatibility with the epoxy resin, and is suitably used for fluidity adjustment such as thickening. Examples of commercially available acrylic resins include “Dianal (registered trademark)” BR series (manufactured by Mitsubishi Rayon Co., Ltd.), “Matsumoto Microsphere (registered trademark)” M, M100, M500 (Matsumoto Yushi Seiyaku Co., Ltd.) And “Nanostrength (registered trademark)” E40F, M22N, M52N (manufactured by Arkema Co., Ltd.), and the like.

  In particular, polyethersulfone and polyetherimide are preferable because these effects can be exhibited without substantially impairing heat resistance. Polyethersulfone includes "Sumika Excel" (registered trademark) 3600P, "Sumika Excel" (registered trademark) 5003P, "Sumika Excel" (registered trademark) 5200P, "Sumika Excel" 2 (registered trademark, above, Sumitomo Chemical Industries) 7200P, “Virantage” (registered trademark) PESU VW-10200, “Virantage” (registered trademark) PESU VW-10700 (registered trademark, manufactured by Solvay Advanced Polymers), “Ultrason” (registered) Trademark) 2020SR (manufactured by BASF Corp.), polyetherimide includes “Ultem” (registered trademark) 1000, “Ultem” (registered trademark) 1010, “Ultem” (registered trademark) 1040 (above, SABIC Innovative Plastics) (Made by Japan GK) Etc. can be used.

  The thermoplastic resin is preferably uniformly dissolved in the epoxy resin composition or finely dispersed in the form of particles so as not to hinder the prepreg manufacturing process centering on impregnation.

  In addition, the amount of the thermoplastic resin to be dissolved in the epoxy resin composition is preferably 1 to 40 parts by mass, more preferably 1 to 25 parts by mass with respect to 100 parts by mass of the epoxy resin. On the other hand, when used in a dispersed state, the amount is preferably 10 to 40 parts by mass, more preferably 15 to 30 parts by mass with respect to 100 parts by mass of the epoxy resin. If the thermoplastic resin is less than this blending amount, the effect of improving toughness may be insufficient. Moreover, when a thermoplastic resin exceeds the said range, impregnation property, tack drape, and heat resistance may fall.

  Furthermore, in order to modify the matrix resin of the present invention, in addition to the thermoplastic resin described above, a thermosetting resin other than an epoxy resin, an elastomer, a filler, rubber particles, thermoplastic resin particles, inorganic particles, and other additives are added. It can also be blended.

  Rubber particles can also be blended with the epoxy resin preferably used in the present invention. As such rubber particles, cross-linked rubber particles, and core-shell rubber particles obtained by graft polymerization of a different polymer on the surface of the cross-linked rubber particles are preferably used from the viewpoint of handleability and the like.

  As commercial products of crosslinked rubber particles, FX501P (manufactured by JSR Co., Ltd.) composed of a crosslinked product of carboxyl-modified butadiene-acrylonitrile copolymer, CX-MN series (manufactured by Nippon Shokubai Co., Ltd.) composed of acrylic rubber fine particles, YR-500 series (manufactured by Nippon Steel Chemical Co., Ltd.) and the like can be used.

  Commercially available core-shell rubber particles include, for example, “Paraloid (registered trademark)” EXL-2655 (manufactured by Kureha Chemical Co., Ltd.), acrylic ester / methacrylic ester, composed of a butadiene / alkyl methacrylate / styrene copolymer. "STAPHYLOID (registered trademark)" AC-3355 made of a copolymer, TR-2122 (above, manufactured by Takeda Pharmaceutical Co., Ltd.), "PARARAID (registered trademark)" made of a copolymer of butyl acrylate and methyl methacrylate “EXL-2611, EXL-3387 (manufactured by Rohm & Haas)”, “Kane Ace (registered trademark)” MX (manufactured by Kaneka Corporation), and the like can be used.

  As the thermoplastic resin particles, those similar to the various thermoplastic resins exemplified above can be used. Among them, polyamide particles and polyimide particles are preferably used, and among polyamides, nylon 12, nylon 6, nylon 11 and nylon 6/12 copolymers can give particularly good adhesive strength with thermosetting resins. Therefore, it is preferable because the delamination strength of the carbon fiber reinforced composite material at the time of falling weight impact is high and the effect of improving impact resistance is high. As commercial products of polyamide particles, SP-500, SP-10 (manufactured by Toray Industries, Inc.), “Orgasol (registered trademark)” (manufactured by Arkema Co., Ltd.) and the like can be used.

  The shape of the thermoplastic resin particles may be spherical particles, non-spherical particles, or porous particles, but the spherical shape is superior in viscoelasticity because it does not deteriorate the flow characteristics of the resin, and there is no origin of stress concentration. This is a preferred embodiment in terms of giving high impact resistance. In the present invention, inorganic particles such as silica, alumina, smectite, and synthetic mica are blended in the epoxy resin composition in order to adjust fluidity such as thickening of the epoxy resin composition within a range that does not impair the effects of the present invention. be able to.

  The prepreg is also preferably used by mixing conductive fillers for the purpose of increasing the contact probability between carbon fibers and improving the conductivity of the carbon fiber reinforced composite material. Examples of such conductive fillers include carbon black, carbon nanotube, vapor grown carbon fiber (VGCF), fullerene, metal nanoparticles, carbon particles, metal-plated thermoplastic resin particles, and metal-plated metals. The thermosetting resin particle | grains etc. which were illustrated previously are mentioned, It may be used independently or may be used together. Of these, carbon black and carbon particles that are inexpensive and highly effective are preferably used. For example, furnace black, acetylene black, thermal black, channel black, ketjen black, and the like can be used. Carbon black blended in two or more types is also preferably used. Further, as such carbon particles, “Bell Pearl (registered trademark)” C-600, C-800, C-2000 (manufactured by Kanebo Co., Ltd.), “NICABEADS (registered trademark)” ICB, PC, MC (Nippon Carbon Co., Ltd.) And the like). Specific examples of the metal-plated thermosetting resin particles include “Micropearl (registered trademark)” AU215, in which divinylbenzene polymer particles are plated with nickel and then gold is plated thereon.

  Next, the manufacturing method of a prepreg is demonstrated.

  A prepreg is obtained by impregnating a sizing agent-coated carbon fiber bundle with a thermosetting resin composition that is a matrix resin. The prepreg can be produced by, for example, a wet method in which a matrix resin is dissolved in a solvent such as methyl ethyl ketone or methanol to lower the viscosity and impregnated, or a hot melt method in which the viscosity is lowered by heating and impregnated.

  In the wet method, after sizing agent-coated carbon fiber bundles are immersed in a liquid containing a matrix resin, the prepreg can be obtained by pulling up and evaporating the solvent using an oven or the like.

  In the hot melt method, a method of directly impregnating a sizing agent-coated carbon fiber bundle with a matrix resin whose viscosity has been reduced by heating, or a film in which a matrix resin composition is once coated on a release paper or the like is first prepared. A prepreg can be produced by a method in which the film is laminated from both sides or one side of the sizing agent-coated carbon fiber bundle and heated and pressed to impregnate the sizing agent-coated carbon fiber bundle into the sizing agent-coated carbon fiber bundle. The hot melt method is a preferable means because there is no solvent remaining in the prepreg.

  In order to form a carbon fiber reinforced composite material using the prepreg of the present invention, a method of heat-curing a matrix resin while applying pressure to the laminate after laminating the prepreg can be used.

  Examples of methods for applying heat and pressure include a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, and an internal pressure molding method. Especially for sporting goods, the wrapping tape method and the internal pressure molding method are preferably employed. The For aircraft applications where higher quality and higher performance laminated composite materials are required, the autoclave molding method is preferably employed. A press molding method is preferably used for various vehicle exteriors.

  The carbon fiber mass fraction of the prepreg of the present invention is preferably 40 to 90 mass%, more preferably 50 to 80 mass%. If the carbon fiber mass fraction is too low, the mass of the resulting composite material may be excessive, which may impair the advantages of the fiber-reinforced composite material having excellent specific strength and specific elastic modulus, and the carbon fiber mass fraction may be high. If the amount is too high, poor impregnation of the matrix resin composition occurs, and the resulting composite material tends to have a lot of voids, and the mechanical properties thereof may be greatly deteriorated.

  In addition, as a method for obtaining a carbon fiber reinforced composite material in the present invention, in addition to a method using a prepreg, hand layup, RTM, “SCRIMP (registered trademark)”, filament winding, pultrusion and resin film infusion. The molding method such as can be selected and applied according to the purpose. By applying any of these molding methods, a fiber-reinforced composite material containing the above-described sizing agent-coated carbon fiber and a cured product of the thermosetting resin composition can be obtained.

  In the carbon fiber reinforced thermoplastic resin composition of the present invention, the sizing agent-coated carbon fiber described above or the sizing agent-coated carbon fiber produced by the method for producing the sizing agent-coated carbon fiber described above, and a thermoplastic resin It is preferable to comprise.

  Examples of the thermoplastic resin used here include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and liquid crystal polyester; polyethylene ( PE), polypropylene (PP), polybutylene, acid-modified polyethylene (m-PE), acid-modified polypropylene (m-PP), polyolefin resins such as acid-modified polybutylene; polyoxymethylene (POM), polyamide (PA), polyphenylene Polyarylene sulfide resins such as sulfide (PPS); polyketone (PK), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyether Nitrile (PEN); Fluorine resin such as polytetrafluoroethylene; Crystalline resin such as liquid crystal polymer (LCP); Polystyrene resin such as polystyrene (PS), acrylonitrile styrene (AS), acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), unmodified or modified polyphenylene ether (PPE), polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polysulfone ( PSU), polyethersulfone, polyarylate (PAR), and other amorphous resins; phenolic resins, phenoxy resins, polystyrene elastomers, polyolefin elastomers, polyurethane elastomers, At least one thermoplastic selected from ester-based elastomers, polyamide-based elastomers, polybutadiene-based elastomers, polyisoprene-based elastomers, various thermoplastic elastomers such as fluorine-based resins and acrylonitrile-based elastomers, and copolymers and modified products thereof. Resins are preferably used.

  The thermoplastic resin used in the present invention is preferably a polyarylene sulfide resin or a polyether ether ketone resin from the viewpoint of heat resistance. From the viewpoint of dimensional stability, polyphenylene ether resin is preferable. From the viewpoint of friction and wear characteristics, polyoxymethylene resin is preferred. From the viewpoint of strength, a polyamide resin is preferable. From the viewpoint of surface appearance, an amorphous resin such as polycarbonate or polystyrene resin is preferable. From the viewpoint of lightness, polyolefin resin is preferable.

  In addition, as a thermoplastic resin, the thermoplastic resin composition containing multiple types of these thermoplastic resins may be used in the range which does not impair the objective of this invention.

  In the present invention, the interaction with the sizing agent when the preferred thermoplastic resin is used will be described.

  In the present invention, the remaining epoxy group, hydroxyl group, amide group, imide group, urethane group, urea group, sulfonyl group, or sulfo group that does not participate in the interaction with the carbon fiber contained in the sizing agent is the main chain of the thermoplastic resin. Ether groups, ester groups, sulfide groups, amide groups, side chain acid anhydride groups, cyano groups, and terminal hydroxyl groups, carboxyl groups, amino groups and other functional groups such as covalent bonds and hydrogen bonds. It is thought that it forms an action and improves interfacial adhesion.

  When polyarylene sulfide resin is used as a matrix resin, interaction such as covalent bond between the thiol group or carboxyl group at the terminal and the epoxy group of the sizing agent, the epoxy group contained in the sizing agent and the sulfide group in the main chain It is considered that a strong interface can be formed by hydrogen bonding with a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, or a sulfo group.

  In addition, when a polyamide resin is used as a matrix resin, it includes a covalent bond between a carboxyl group or amino group at the terminal and an epoxy group contained in the sizing agent, an amide group in the main chain, and a sizing agent. It is considered that a strong interface can be formed by hydrogen bonding with an epoxy group, a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, or a sulfo group.

  In addition, when using a polyester resin or polycarbonate resin as a matrix resin, interactions such as covalent bonding between a carboxyl group or hydroxyl group at the terminal and an epoxy group contained in the sizing agent, an ester group in the main chain, and sizing It is considered that a strong interface can be formed by hydrogen bonding with an epoxy group, a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, or a sulfo group contained in the agent.

  In addition, when using a polystyrene resin such as ABS resin as a matrix resin, a cyano group in the side chain and an epoxy group, a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group contained in the sizing agent It is considered that a strong interface can be formed by hydrogen bonding with a sulfo group.

  Also, among polyolefin resins, particularly when acid-modified polyolefin resin is used as a matrix resin, an epoxy group, a hydroxyl group, an amide group, an acid anhydride group or a carboxyl group in a side chain and a sizing agent, It is considered that a strong interface can be formed by hydrogen bonding with an imide group, a urethane group, a urea group, a sulfonyl group, or a sulfo group.

  The carbon fiber reinforced thermoplastic resin composition of the present invention can be used in the form of molding materials such as pellets, stampable sheets and prepregs. The most preferred molding material is pellets. Pellets are generally obtained by melt-kneading, extruding and pelletizing thermoplastic resin pellets and continuous carbon fibers or discontinuous carbon fibers cut to a specific length (chopped carbon fibers) in an extruder. It refers to what was given.

  Examples of the molding method of the molding material include injection molding (injection compression molding, gas assist injection molding, insert molding, etc.), blow molding, rotational molding, extrusion molding, press molding, transfer molding, and filament winding molding. Among these, injection molding is preferably used from the viewpoint of productivity. A molded product can be obtained by these molding methods.

  In the present invention, the molded body of the carbon fiber reinforced thermoplastic resin composition has a bending strength (S1) before being immersed in hot water at 80 ° C. and a bending strength (S2) after being immersed in hot water at 80 ° C. for 1000 hours. The ratio (S2 / S1) is preferably 0.75 or more. When (S2 / S1) is 0.75 or more, even when used in a high-temperature and high-humidity environment, the physical properties of the carbon fiber-reinforced thermoplastic resin composition can be sufficiently maintained, which is preferable. 0.80 or more is more preferable.

  In the present invention, the molded body used for measuring the bending strength before and after immersion in hot water is obtained by cutting a bending strength test piece having a length of 130 ± 1 mm and a width of 25 ± 0.2 mm from an injection molded product. Can do. According to the test method specified in ASTM D-790 (2004), using a three-point bending test jig (indenter 10 mm, fulcrum 10 mm), the support span is set to 100 mm, and the bending strength is measured at a crosshead speed of 5.3 mm / min. did. In the present invention, “Instron (registered trademark)” universal testing machine 4201 type (manufactured by Instron) was used as a testing machine. The number of measurements is n = 5, and the average value is the bending strength (S1). Moreover, after immersing the said test piece in 80 degreeC hot water for 1000 hours and removing the surface water | moisture content, let the bending strength measured similarly be (S2).

  In the present invention, the thermoplastic resin is preferably at least one selected from the group consisting of a polyarylene sulfide resin, a polycarbonate resin, and a polyolefin resin. The above resin has high water resistance, and physical properties are not easily lowered by water absorption by the resin alone. On the other hand, when carbon fiber is used as a reinforcing material, physical properties are reduced due to water absorption of the sizing agent at the interface between the carbon fiber and the matrix resin. When the sizing agent containing the water-insoluble epoxy compound (B) in the present invention is used, water absorption of the sizing agent can be suppressed, and the water resistance of the carbon fiber reinforced thermoplastic resin composition is improved.

  The carbon fiber reinforced composite material using the sizing agent-coated carbon fiber of the present invention is used for computer structures such as aircraft structural members, windmill blades, automobile outer plates, IC trays and notebook PC housings, and golf shafts. It is preferably used for sports applications such as bats, badminton and tennis rackets.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not restrict | limited by these Examples.

(1) X-ray photoelectron spectroscopy at 400 eV on the sizing agent-coated carbon fiber sizing agent surface In the present invention, the peak ratio of (a) and (b) on the sizing agent-coated carbon fiber sizing agent surface is the X-ray photoelectron It was determined by spectroscopy according to the following procedure. The sizing agent-coated carbon fibers were cut to 20 mm, spread and arranged on a copper sample support, and then Saga synchrotron was used as an X-ray source, and the excitation energy was measured at 400 eV and the photoelectron escape angle was 55 °. The measurement was performed while keeping the inside of the sample chamber at 1 × 10 ⁻⁸ Torr. As correction of the peak accompanying charging during measurement, first, the binding energy value of the main peak of C _1s was adjusted to 284.6 eV. At this time, the peak area of C _1s was obtained by drawing a straight baseline in the range of 282 to 296 eV. Further, a linear base line of 282 to 296 eV whose area was obtained at the C _1s peak was defined as the origin (zero point) of photoelectron intensity, and (a) a binding energy 284 attributed to CHx, CC, C = C. The peak height (cps) of .6 eV (cps: photoelectron intensity per unit time) and (b) the peak height (cps) of the binding energy 286.1 eV attributed to the CO component are determined. b) was calculated.

When the peak of (b) is larger than (a), when the binding energy value of the C _1s main peak is adjusted to 284.6, the C _1s peak does not fall within the range of 282 to 296 eV. In that case, after adjusting the binding energy value of the main peak of C _1s to 286.1 eV, (a) / (b) was calculated by the above method.

(2) Cleaning of sizing agent of sizing agent-coated carbon fiber 2 g of sizing agent-coated carbon fiber was immersed in 50 ml of acetone and subjected to ultrasonic cleaning for 30 minutes three times. Subsequently, the substrate was immersed in 50 ml of methanol, subjected to ultrasonic cleaning for 30 minutes once and dried.

(3) Strand tensile strength and elastic modulus of carbon fiber bundle The strand tensile strength and strand elastic modulus of the carbon fiber bundle were determined according to the following procedure in accordance with the resin-impregnated strand test method of JIS-R-7608 (2004). . As the resin formulation, “Celoxide (registered trademark)” 2021P (manufactured by Daicel Chemical Industries) / 3 boron trifluoride monoethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) / Acetone = 100/3/4 (part by mass) is used. As curing conditions, normal pressure, temperature of 125 ° C., and time of 30 minutes were used. Ten strands of the carbon fiber bundle were measured, and the average value was defined as the strand tensile strength and the strand elastic modulus.

(4) Surface oxygen concentration of carbon fiber (O / C)
The surface oxygen concentration (O / C) of the carbon fiber was determined by X-ray photoelectron spectroscopy according to the following procedure. First, the carbon fiber from which the dirt adhering to the surface with a solvent is removed is cut to about 20 mm and spread on a copper sample support. Next, the sample support was set in the sample chamber, and the inside of the sample chamber was kept at 1 × 10 ⁻⁸ Torr. Subsequently, AlKα ₁ and ₂ were used as the X-ray source, and the photoelectron escape angle was 90 °. In addition, the binding energy value of the C _1s main peak (peak top) was adjusted to 284.6 eV as a correction value for the peak accompanying charging during measurement. The C _1s peak area was determined by drawing a straight base line in the range of 282 to 296 eV. The O _1s peak area was determined by drawing a straight base line in the range of 528 to 540 eV. Here, the surface oxygen concentration is calculated as an atomic ratio by using a sensitivity correction value unique to the apparatus from the ratio of the O _1s peak area to the C _1s peak area. As the X-ray photoelectron spectroscopy apparatus, ESCA-1600 manufactured by ULVAC-PHI Co., Ltd. was used, and the sensitivity correction value unique to the apparatus was 2.33.

(5) Carbon fiber surface carboxyl group concentration (COOH / C), surface hydroxyl group concentration (COH / C)
The surface hydroxyl group concentration (COH / C) was determined by chemical modification X-ray photoelectron spectroscopy according to the following procedure.

The carbon fiber bundles from which the sizing agent and the like have been removed with a solvent are cut and spread and arranged on a platinum sample support. At room temperature in dry nitrogen gas containing 0.04 mol / liter of anhydrous trifluoride acetic acid gas. After 10 minutes exposure and chemical modification treatment, it was mounted on an X-ray photoelectron spectrometer with a photoelectron escape angle of 35 °, AlKα _1,2 was used as an X-ray source, and the inside of the sample chamber was at a vacuum of 1 × 10 ⁻⁸ Torr. Keep on. As correction of the peak accompanying charging during measurement, first, the binding energy value of the C _1s main peak was adjusted to 284.6 eV. The C _1s peak area [C _1s ] is obtained by drawing a straight base line in the range of 282 to 296 eV, and the F _1s peak area [F _1s ] is obtained by drawing a straight base line in the range of 682 to 695 eV. Asked. Moreover, the reaction rate r was calculated | required from _C1s peak division _| segmentation of the polyvinyl alcohol chemically modified simultaneously.

  The surface hydroxyl group concentration (COH / C) was represented by the value calculated by the following formula.

COH / C = {[F _1s ] / (3k [C _1s ] −2 [F _1s ]) r} × 100 (%)
Note that k is a sensitivity correction value of the F _1s peak area with respect to the C _1s peak area specific to the apparatus, and the sensitivity correction value specific to the apparatus in the model SSX-100-206 manufactured by SSI of the United States was 3.919. .

The surface carboxyl group concentration (COOH / C) was determined by chemical modification X-ray photoelectron spectroscopy according to the following procedure. First, carbon fiber bundles from which the sizing agent and the like have been removed with a solvent are cut and spread and arranged on a platinum sample support, and 0.02 mol / liter of trifluorinated ethanol gas, 0.001 mol / liter of dicyclohexyl. The sample was exposed to air containing carbodiimide gas and 0.04 mol / liter pyridine gas at 60 ° C for 8 hours, chemically modified, mounted on an X-ray photoelectron spectrometer with a photoelectron escape angle of 35 °, and used as an X-ray source. Using AlKα ₁ and ₂ , the inside of the sample chamber is kept at a vacuum of 1 × 10 ⁻⁸ Torr. As correction of the peak accompanying charging during measurement, first, the binding energy value of the C _1s main peak was adjusted to 284.6 eV. The C _1s peak area [C _1s ] is obtained by drawing a straight base line in the range of 282 to 296 eV, and the F _1s peak area [F _1s ] is obtained by drawing a straight base line in the range of 682 to 695 eV. Asked. Simultaneously, the reaction rate r was determined from the C _1s peak splitting of the polyacrylic acid chemically modified, and the residual rate m of the dicyclohexylcarbodiimide derivative was determined from the O _1s peak splitting.

  The surface carboxyl group concentration COOH / C was represented by the value calculated by the following formula.

COOH / C = {[F _1s ] / (3k [C _1s ] − (2 + 13 m) [F _1s ]) r} × 100 (%)
Note that k is a sensitivity correction value of the F _1s peak area with respect to the C _1s peak area unique to the apparatus, and the sensitivity correction value specific to the apparatus when the model SSX-100-206 manufactured by SSI of the United States is used is 3.919. Met.

(6) Epoxy value of sizing agent The epoxy value of the sizing agent was determined by acid-base titration by dissolving the sizing agent from which the solvent had been removed in N, N-dimethylformamide, opening the epoxy group with hydrochloric acid.

(7) Hydroxyl value of sizing agent The hydroxyl value of the sizing agent is determined by dissolving the sizing agent from which the solvent has been removed in N, N-dimethylformamide, acetylating the hydroxyl group with acetic anhydride, and converting the generated acetic acid to potassium hydroxide. It was determined by titrating with a solution. Since the epoxy group is also titrated, it was corrected with the value of the epoxy value measured in (6).

(8) Method of measuring sizing adhesion amount Electricity set to a temperature of 450 ° C. in a nitrogen stream of 50 ml / min after weighing about 2 g of sizing adhesion carbon fiber bundle (W1) (reading to the fourth decimal place) Leave in a furnace (capacity 120 cm ³ ) for 15 minutes to completely pyrolyze the sizing agent. Then, the carbon fiber bundle is transferred to a container in a dry nitrogen stream of 20 liters / minute and cooled for 15 minutes, and the carbon fiber bundle is weighed (W2) (reads up to the fourth decimal place), and the sizing adhesion amount is obtained by W1-W2. . A value obtained by converting this sizing adhesion amount into an amount with respect to 100 parts by mass of the carbon fiber bundle (rounded off to the third decimal place) was defined as a mass part of the adhering sizing agent. The measurement was performed twice, and the average value was defined as the mass part of the sizing agent.

(9) Measurement of interfacial shear strength (IFSS) The measurement of interfacial shear strength (IFSS) was performed according to the following procedures (a) to (d).

(A) Preparation of resin 100 parts by mass of a bisphenol A type epoxy compound “jER (registered trademark)” 828 (manufactured by Mitsubishi Chemical Corporation) and 14.5 parts by mass of metaphenylenediamine (manufactured by Sigma-Aldrich Japan Co., Ltd.) Each was placed in a container. Thereafter, the mixture was heated at a temperature of 75 ° C. for 15 minutes in order to reduce the viscosity of the jER828 and dissolve the metaphenylenediamine. Then, both were mixed well and vacuum defoaming was performed at a temperature of 80 ° C. for about 15 minutes.

(B) Fixing the carbon fiber single yarn to the dedicated mold The single fiber was extracted from the carbon fiber bundle, and both ends were fixed with an adhesive in a state where a constant tension was applied to the single fiber in the longitudinal direction of the dumbbell mold. Then, in order to remove the water | moisture content adhering to carbon fiber and a mold, it vacuum-dried for 30 minutes or more at the temperature of 80 degreeC. The dumbbell mold was made of silicone rubber, and the shape of the cast part was a center part width of 5 mm, a length of 25 mm, both end part widths of 10 mm, and an overall length of 150 mm.

(C) From resin casting to curing The resin adjusted in the above procedure (b) is poured into the mold after the vacuum drying in the above step (b), and the temperature rising rate is 1.5 ° C. / The temperature rises to 75 ° C in minutes and is held for 2 hours, then rises to a temperature of 125 ° C at a heating rate of 1.5 ° C / min, held for 2 hours, and then reaches a temperature of 30 ° C at a cooling rate of 2.5 ° C / min. The temperature dropped. Then, it demolded and the test piece was obtained.

(D) Measurement of interfacial shear strength (IFSS) A tensile force was applied to the test piece obtained in the above procedure (c) in the fiber axis direction (longitudinal direction) to cause a strain of 12%, and then the test piece was tested with a polarizing microscope. The fiber breakage number N (pieces) in the range of 22 mm at the center of each piece was measured. Next, the average broken fiber length la was calculated by the formula: la (μm) = 22 × 1000 (μm) / N (pieces). Next, the critical fiber length lc was calculated from the average breaking fiber length la by the formula of lc (μm) = (4/3) × la (μm). The strand tensile strength σ and the diameter d of the carbon fiber single yarn were measured, and the interface shear strength IFSS (c), which is an index of the bond strength between the carbon fiber and the resin interface, was calculated by the following equation. In the examples, the average of the number of measurements n = 5 was used as the test result.
Interfacial shear strength IFSS (c) (MPa) = σ (MPa) × d (μm) / (2 × lc) (μm)
IFSS values of 43 MPa or more were evaluated as ◎, 40 MPa or more and less than 43 MPa as ◯, 30 MPa or more and less than 40 MPa as Δ, and less than 30 MPa as x. ◎ and ○ are preferable ranges in the present invention.

(10) Interfacial shear strength after storage in wet environment After storing the carbon fiber bundle at a temperature of 50 ° C. and a humidity of 80% for 14 days, the interfacial shear strength (IFSS) was measured in the same manner as in (8). The relationship between IFSS (c) MPa measured in (8) and IFSS (d) MPa after storage in a wet environment, that is, the rate of decrease after aging was calculated from the following formula (1).

((C)-(d)) / (c) (1)
The rate of decrease after change over time is less than 10%, 、 １０ is 10% or more and less than 20%, ◯ is 20% or more and less than 30%, and 30% or more is ×. ◎ and ○ are preferable ranges in the present invention.

(11) Definition of 0 ° of fiber reinforced composite material As described in JIS K7017 (1999), the fiber direction of a unidirectional fiber reinforced composite material is defined as the axial direction, and the axial direction is defined as the 0 ° axis. The direction was defined as 90 °.

(12) Measurement of 0 ° tensile strength of fiber reinforced composite material Cut a unidirectional prepreg within 24 hours after preparation into a predetermined size, laminate 6 sheets in one direction, perform a vacuum bag, and use an autoclave And cured at a temperature of 180 ° C. and a pressure of 6 kg / cm ² for 2 hours to obtain a unidirectional reinforcing material (carbon fiber reinforced composite material). The unidirectional reinforcing material was cut into a width of 12.7 mm and a length of 230 mm, and a glass fiber reinforced plastic tab having a length of 1.2 mm and a length of 50 mm was bonded to both ends to obtain a test piece. The test piece thus obtained was subjected to a tensile test at a crosshead speed of 1.27 mm / min using an Instron universal testing machine.

In the present invention, the value obtained by dividing the 0 ° tensile strength value (e) MPa by the strand strength value obtained in (2) was used as the strength utilization factor (%), and the following formula was used.
Strength utilization rate = tensile strength / ((CF basis weight / 190) × Vf / 100 × strand strength) × 100
CF basis weight = 190 g / m ²
Vf = 56%
A strength utilization rate of 83% or more was evaluated as ◎, 80% or more and less than 83% as ７８, 78% or more and less than 80% as Δ, and less than 78% as ×. ◎ and ○ are preferable ranges in the present invention.

(13) Measurement of emulsion particle size by particle size distribution meter The average particle size of cumulant was measured using a particle size distribution meter (FAPR-1000 manufactured by Otsuka Electronics Co., Ltd.) with respect to an emulsion solution having a mass other than water of 5% by mass with respect to the aqueous solution. In the examples, measurement was performed at n = 3, and the average was taken as the measurement result. As an index of the stability of the particles, the average particle size is 100 nm or more and less than 300 nm, ◯, 300 nm or more and less than 500 nm is given by ○, 500 nm or more and less than 600 nm by Δ, and 600 nm or more by ×. ◎ and ○ are preferable ranges in the present invention.

(14) Bending characteristic evaluation method of injection molded product A bending strength test piece having a length of 130 ± 1 mm and a width of 25 ± 0.2 mm was cut out from the obtained injection molded product. According to the test method specified in ASTM D-790 (2004), using a three-point bending test jig (indenter 10 mm, fulcrum 10 mm), the support span is set to 100 mm, and the bending strength is measured at a crosshead speed of 5.3 mm / min. did. In this example, “Instron (registered trademark)” universal testing machine 4201 type (manufactured by Instron) was used as a testing machine. The number of measurements was n = 5, and the average value was the bending strength (S1). Moreover, after the said test piece was immersed in 80 degreeC hot water for 1000 hours, the water | moisture content of the surface was removed, the bending strength measured similarly was set to (S2). As an index of hot water resistance, (S2 / S1) is preferably 0.75 or more.

  The materials and components used in each example and each comparative example are as follows. In addition, solid content residual amount mixes 10 mass parts of epoxy compounds with 90 mass parts of water at 25 degreeC, after stirring with a stirrer for 24 hours or more, and filtering with the filter paper applicable to JIS P3801 (1956) 1 type. Indicates the weight of the remaining solid.

-(A) component: A-1 to A-4
A-1: “Denacol (registered trademark)” EX-810 (manufactured by Nagase ChemteX Corporation)
Diglycidyl ether of ethylene glycol Epoxy value: 8.85 meq / g, Hydroxyl value: 0 meq / g, Number of epoxy groups: 2, Solid content remaining: 0%
A-2: “Denacol (registered trademark)” EX-611 (manufactured by Nagase ChemteX Corporation)
Sorbitol polyglycidyl ether Epoxy value: 5.9 meq / g, Hydroxyl value: 3.8 meq / g, Number of epoxy groups: 4, Solid content remaining: 52%
A-3: “Denacol (registered trademark)” EX-313 (manufactured by Nagase ChemteX Corporation)
Glycerol polyglycidyl ether Epoxy value: 7.09 meq / g, Hydroxyl value: 3.66 meq / g, Number of epoxy groups: 2, Solid content remaining: 1%
A-4: “Denacol (registered trademark)” EX-521 (manufactured by Nagase ChemteX Corporation)
Polyglycerin polyglycidyl ether Epoxy value: 5.46 meq / g, Hydroxyl value: 2.58 meq / g, Epoxy group number: 6.3, Solid content residual amount: 0%.

-(B) component: B-1 to B-6
B-1: “jER (registered trademark)” 152 (manufactured by Mitsubishi Chemical Corporation)
Glycidyl ether of phenol novolac Epoxy value: 5.71 meq / g, Epoxy group number: 3, Solid content residual amount: 90% or more B-2: “Epicron (registered trademark)” N660 (manufactured by DIC Corporation)
Cresol novolac type epoxy resin Epoxy value: 4.85 meq / g, number of epoxy groups: 3, solid content remaining: 90% or more B-3: “jER (registered trademark)” 828 (manufactured by Mitsubishi Chemical Corporation)
Diglycidyl ether of bisphenol A Epoxy value: 5.29 meq / g, number of epoxy groups: 2, solid content remaining: 90% or more B-4: “jER (registered trademark)” 1001 (manufactured by Mitsubishi Chemical Corporation)
Diglycidyl ether of bisphenol A Epoxy value: 2.11 meq / g, Number of epoxy groups: 2, Solid content remaining: 90% or more B-5: “Denacol (registered trademark)” EX-731 (manufactured by Nagase ChemteX Corporation) )
N-glycidylphthalimide Epoxy value: 4.63 meq / g, Number of epoxy groups: 1, Solid content remaining: 90% or more B-6: “jER (registered trademark)” 807 (manufactured by Mitsubishi Chemical Corporation)
Diglycidyl ether of bisphenol F Epoxy value: 5.9 meq / g, number of epoxy groups: 2, solid content remaining: 90% or more B-7: “Denacol (registered trademark)” EX-411 (manufactured by Nagase ChemteX Corporation) )
Pentaerythritol polyglycidyl ether Epoxy value: 4.37 meq / g, Hydroxyl value: 0 meq / g, Number of epoxy groups: 4, Solid content remaining: 90%
B-8: “Denacol (registered trademark)” EX-622 (manufactured by Nagase ChemteX Corporation)
Sorbitol polyglycidyl ether Epoxy value: 5.24 meq / g, Hydroxyl value: 1.19 meq / g, Number of epoxy groups: 5, Solid content remaining: 85%.

Epoxy compound (D1): D-1, D-2
D-1: Tetraglycidyldiaminodiphenylmethane, “Sumiepoxy (registered trademark)” ELM434 (manufactured by Sumitomo Chemical Co., Ltd.)
Epoxy value: 8.33 meq / g
D-2: “jER (registered trademark)” 828 (manufactured by Mitsubishi Chemical Corporation)
Diglycidyl ether of bisphenol A Epoxy value: 5.29 meq / g.

-Latent curing agent (E) component: E-1
E-1: “Seika Cure (registered trademark)” S (4,4′-diaminodiphenyl sulfone, manufactured by Wakayama Seika Co., Ltd.).
-Thermoplastic resin "Sumika Excel (registered trademark)" 5003P (polyethersulfone, manufactured by Sumitomo Chemical Co., Ltd.).

Polyarylene sulfide resin:
Polyphenylene sulfide (PPS) resin pellet: “Torelina (registered trademark)” M2888 (manufactured by Toray Industries, Inc.).

Polyamide resin:
Polyamide 66 (PA) resin pellet: “Amilan (registered trademark)” CM3001 (manufactured by Toray Industries, Inc.).

Polycarbonate resin:
Polycarbonate (PC) resin pellet: “Lexan (registered trademark)” 141R (SABIC).

Polyolefin resin:
Polypropylene (PP) resin pellets: a mixture of unmodified PP resin pellets and acid-modified PP resin pellets (unmodified PP resin pellets: “Prime Polypro (registered trademark)” J830HV (manufactured by Prime Polymer Co., Ltd.), 50 parts by mass, Acid-modified PP resin pellets: “Admer (registered trademark)” QE800 (manufactured by Mitsui Chemicals, Inc., 50 parts by mass).

Example 1
This example comprises the following I step, II step and III step.

-Step I: Process for producing carbon fiber as raw material A copolymer composed of 99 mol% acrylonitrile and 1 mol% itaconic acid is spun and fired, the total number of filaments is 24,000, and the fiber density is 1,000. A carbon fiber having a tex, a specific gravity of 1.8, a strand tensile strength of 5.9 GPa, and a strand tensile elastic modulus of 295 GPa was obtained. Subsequently, the carbon fiber was subjected to an electrolytic surface treatment with an aqueous solution of ammonium hydrogen carbonate having a concentration of 0.1 mol / l as an electrolytic solution at an electric charge of 50 coulomb per gram of carbon fiber. The carbon fiber subjected to the electrolytic surface treatment was subsequently washed with water and dried in heated air at a temperature of 150 ° C. to obtain a carbon fiber as a raw material. At this time, the surface oxygen concentration O / C was 0.15, the surface carboxyl group concentration COOH / C was 0.005, and the surface hydroxyl group concentration COH / C was 0.018. The surface roughness (Ra) of the carbon fiber at this time was 3.0 nm. This was designated as carbon fiber A.

-Step II: Step of attaching sizing agent to carbon fiber (B) As component (B-1), 20 parts by mass, (C) 20 parts by mass of component and 10 parts by mass of emulsifier were prepared. Thereafter, 50 parts by mass of (A-4) as component (A) was mixed to prepare a sizing solution. As component (C), 2 mol of an adduct of bisphenol A with 2 mol of ethylene oxide and 1.5 mol of maleic acid and 0.5 mol of sebacic acid, and polyoxyethylene (70 mol) styrenation as an emulsifier (5 Mol) cumylphenol was used. After this sizing agent was applied to the carbon fiber surface-treated by the dipping method, heat treatment was performed at a temperature of 210 ° C. for 75 seconds to obtain a sizing agent-coated carbon fiber bundle. The adhesion amount of the sizing agent was adjusted to 1.0 mass% with respect to the sizing agent-coated carbon fiber. Subsequently, X-ray photoelectron spectroscopy measurement on the surface of the sizing agent, interfacial shear strength (IFSS) of the sizing agent-coated carbon fiber, and interfacial shear strength of the sizing agent-coated carbon fiber stored in a wet environment were measured. The results are summarized in Table 1. As a result, it was confirmed that the composition of the sizing agent on the carbon fiber surface was as expected. Moreover, it turned out that the adhesiveness measured by IFSS is high enough, and the decreasing rate of the adhesiveness after wet environment storage is low.

Step III: Preparation, molding and evaluation of prepreg In a kneading apparatus, 80 parts by mass of (D-1) and 20 parts by mass of (D-2) as component (D) and 10 parts by mass of Sumika Excel 5003P After mixing and dissolving, 40 parts by mass of (E-1) 4,4′-diaminodiphenylsulfone as a curing agent (E) component is kneaded to prepare an epoxy resin composition for a carbon fiber reinforced composite material. did.

The obtained epoxy resin composition was coated on a release paper with a resin basis weight of 52 g / m ² using a knife coater to prepare a resin film. This resin film is superposed on both sides of a sizing agent-coated carbon fiber (weight per unit area 190 g / m ² ) aligned in one direction, and a heat roll is used to heat and press at 100 ° C. and 1 atm. Was impregnated into carbon fiber coated with a sizing agent to obtain a prepreg. Subsequently, a 0 ° tensile test was performed. The results are shown in Table 1. It was confirmed that the 0 ° tensile strength utilization rate was sufficiently high. The results are shown in Table 1.

(Examples 2 to 10)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was obtained in the same manner as in Example 1 except that the component (B) shown in Table 1 was used as the sizing agent. Subsequently, X-ray photoelectron spectroscopy measurement on the surface of the sizing agent, interfacial shear strength (IFSS) of the sizing agent-coated carbon fiber, and interfacial shear strength of the sizing agent-coated carbon fiber stored in a wet environment were measured. As a result, it was confirmed that the composition of the sizing agent on the carbon fiber surface was as expected. Moreover, it turned out that the adhesiveness measured by IFSS is high enough, and the decreasing rate of the adhesiveness after wet environment storage is low. The results are shown in Table 1.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. It was confirmed that the 0 ° tensile strength utilization rate was sufficiently high. The results are shown in Table 1.

(Examples 11 to 15)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was obtained in the same manner as in Example 3 except that the component (A) shown in Table 2 was used as the sizing agent. Subsequently, X-ray photoelectron spectroscopy measurement on the surface of the sizing agent, interfacial shear strength (IFSS) of the sizing agent-coated carbon fiber, and interfacial shear strength of the sizing agent-coated carbon fiber stored in a wet environment were measured. As a result, it was confirmed that the composition of the sizing agent on the carbon fiber surface was as expected. Moreover, it turned out that the adhesiveness measured by IFSS is high enough, and the decreasing rate of the adhesiveness after wet environment storage is low. The results are shown in Table 2.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. It was confirmed that the 0 ° tensile strength utilization rate was sufficiently high. The results are shown in Table 2.

(Examples 16 to 20)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fibers were obtained in the same manner as in Example 3 except that the mass ratio shown in Table 2 was used as the sizing agent. Subsequently, X-ray photoelectron spectroscopy measurement on the surface of the sizing agent, interfacial shear strength (IFSS) of the sizing agent-coated carbon fiber, and interfacial shear strength of the sizing agent-coated carbon fiber stored in a wet environment were measured. As a result, it was confirmed that the composition of the sizing agent on the carbon fiber surface was as expected. Moreover, it turned out that the adhesiveness measured by IFSS is high enough, and the decreasing rate of the adhesiveness after wet environment storage is low. The results are shown in Table 2.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. It was confirmed that the 0 ° tensile strength utilization rate was sufficiently high. The results are shown in Table 2.

(Example 21)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.

Step II: A step of attaching a sizing agent to carbon fiber (A) 50 parts by mass of (A-4) as component, 20 parts by mass of (B-3) as component (B), and 20 aromatic polyester A sizing solution was prepared by dissolving 10 parts by mass of an emulsifier and 10 parts by mass of DMF. In the same manner as in Example 1, this sizing agent was applied to the carbon fiber surface-treated by the dipping method, and then heat treated at a temperature of 210 ° C. for 75 seconds to obtain a sizing agent-coated carbon fiber bundle. The adhesion amount of the sizing agent was adjusted to be 1.0 part by mass with respect to 100 parts by mass of the surface-treated carbon fiber. Subsequently, X-ray photoelectron spectroscopy measurement on the surface of the sizing agent, interfacial shear strength (IFSS) of the sizing agent-coated carbon fiber, and interfacial shear strength of the sizing agent-coated carbon fiber stored in a wet environment were measured. As a result, it was confirmed that the composition of the sizing agent on the carbon fiber surface was as expected. Moreover, it turned out that the adhesiveness measured by IFSS is high enough, and the decreasing rate of the adhesiveness after wet environment storage is low. The results are shown in Table 3.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. It was confirmed that the 0 ° tensile strength utilization rate was sufficiently high. The results are shown in Table 3.

(Example 22)
-Step I: Step of producing carbon fiber as raw material A copolymer composed of 99 mol% of acrylonitrile and 1 mol% of itaconic acid is spun and fired, the total number of filaments is 24,000, the fine density is 490 tex, A carbon fiber having a specific gravity of 1.8, a strand tensile strength of 6.3 GPa, and a strand tensile modulus of 330 GPa was obtained. Next, the carbon fiber was subjected to electrolytic surface treatment with an aqueous solution of ammonium hydrogen carbonate having a concentration of 0.1 mol / l as an electrolytic solution at an electric quantity of 80 coulomb per gram of carbon fiber. The carbon fiber subjected to the electrolytic surface treatment was subsequently washed with water and dried in heated air at a temperature of 150 ° C. to obtain a carbon fiber as a raw material. At this time, the surface oxygen concentration O / C was 0.20, the surface carboxylic acid concentration COOH / C was 0.008, and the surface hydroxyl group concentration COH / C was 0.030. This was designated as carbon fiber B.

Step II: Step of attaching sizing agent to carbon fiber The same procedure as in Example 3 was performed. As a result, it was confirmed that the composition of the sizing agent on the carbon fiber surface was as expected. Moreover, it turned out that the adhesiveness measured by IFSS is high enough, and the decreasing rate of the adhesiveness after wet environment storage is low. The results are shown in Table 3.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. It was confirmed that the 0 ° tensile strength utilization rate was sufficiently high. The results are shown in Table 3.

(Example 23)
-Step I: Step of producing carbon fiber as raw material Implemented except that sulfuric acid aqueous solution having a concentration of 0.05 mol / l was used as the electrolytic solution and the amount of electricity was subjected to electrolytic surface treatment at 10 coulomb per gram of carbon fiber. Same as Example 1. At this time, the surface oxygen concentration O / C was 0.09, the surface carboxylic acid concentration COOH / C was 0.004, and the surface hydroxyl group concentration COH / C was 0.003. This was designated as carbon fiber C.

Step II: Step of attaching sizing agent to carbon fiber The same procedure as in Example 3 was performed. As a result, it was confirmed that the composition of the sizing agent on the carbon fiber surface was as expected. Moreover, it turned out that the adhesiveness measured by IFSS is high enough, and the decreasing rate of the adhesiveness after wet environment storage is low. The results are shown in Table 3.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. It was confirmed that the 0 ° tensile strength utilization rate was sufficiently high. The results are shown in Table 3.

(Examples 24-27)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.

Step II: Step of attaching sizing agent to carbon fiber The procedure was the same as Example 33 except that the heat treatment temperature was as shown in Table 3. As a result, it was confirmed that the composition of the sizing agent on the carbon fiber surface was as expected. Moreover, it turned out that the adhesiveness measured by IFSS is high enough, and the decreasing rate of the adhesiveness after wet environment storage is low. The results are shown in Table 3.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. It was confirmed that the 0 ° tensile strength utilization rate was sufficiently high. The results are shown in Table 3.

(Examples 28 and 29)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.

Step II: Step of attaching sizing agent to carbon fiber The same procedure as in Example 3 was conducted except that the heat treatment temperature was as shown in Table 3. As a result, it was confirmed that the composition of the sizing agent on the carbon fiber surface was as expected. Moreover, although the initial adhesiveness measured by IFSS was somewhat insufficient, it was found that the rate of decrease in adhesiveness after storage in a wet environment was low. The results are shown in Table 3.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. It was confirmed that the 0 ° tensile strength utilization rate was sufficiently high. The results are shown in Table 3.

(Example 30)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.

-Step II: Step of attaching sizing agent to carbon fiber (A) After mixing 50 parts by mass of (A-4) as component and 20 parts by mass of (B-1) as component (B), (C ) 20 parts by mass of component and 10 parts by mass of emulsifier were mixed to prepare an aqueous dispersion emulsion. As component (C), 2 mol of an adduct of bisphenol A with 2 mol of ethylene oxide and 1.5 mol of maleic acid and 0.5 mol of sebacic acid, and polyoxyethylene (70 mol) styrenation as an emulsifier (5 Mol) cumylphenol was used. After this sizing agent was applied to the carbon fiber surface-treated by the dipping method, heat treatment was performed at a temperature of 210 ° C. for 75 seconds to obtain a sizing agent-coated carbon fiber bundle. The adhesion amount of the sizing agent was adjusted to 1.0 mass% with respect to the sizing agent-coated carbon fiber. Subsequently, X-ray photoelectron spectroscopy measurement on the surface of the sizing agent, interfacial shear strength (IFSS) of the sizing agent-coated carbon fiber, and interfacial shear strength of the sizing agent-coated carbon fiber stored in a wet environment were measured. The results are summarized in Table 1. As a result, it was confirmed that the composition of the sizing agent on the carbon fiber surface was as expected. Moreover, it turned out that the adhesiveness measured by IFSS is high enough, and the decreasing rate of the adhesiveness after wet environment storage is low.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. The 0 ° tensile strength utilization rate was slightly insufficient. The results are shown in Table 3.

(Comparative Examples 1-3)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.

-Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was obtained in the same manner as in Example 3 except that the mass ratio shown in Table 4 was used as the sizing agent. Component of binding energy (284.6 eV) belonging to (a) CHx, CC, C = C in C _1s core spectrum measured by X-ray photoelectron spectroscopy with excitation energy of 400 eV and photoelectron escape angle of 55 ° The ratio (a) / (b) of the height (cps) of the component (b) and the height (cps) of the component of the binding energy (286.1 eV) attributed to C—O is greater than 0.90. Was out of range. Moreover, it turned out that the initial adhesiveness measured by IFSS is low. The results are shown in Table 4.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. It was found that the 0 ° tensile strength utilization rate was low. The results are shown in Table 4.

(Comparative Example 4)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.

-Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was obtained in the same manner as in Example 3 except that the mass ratio shown in Table 4 was used as the sizing agent. Component of binding energy (284.6 eV) belonging to (a) CHx, CC, C = C in C _1s core spectrum measured by X-ray photoelectron spectroscopy with excitation energy of 400 eV and photoelectron escape angle of 55 ° The ratio (a) / (b) of the height (cps) of the component (b) and the height (cps) of the component of the binding energy (286.1 eV) attributed to C—O is smaller than 0.50. Was out of range. The initial adhesion measured by IFSS was sufficiently high, but the IFSS after storage in a wet environment decreased. The results are shown in Table 4.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. The 0 ° tensile strength utilization factor was good. The results are shown in Table 4.

(Comparative Examples 5 and 6)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon in the same manner as in Example 1 except that (A) component and (B) component are shown in Table 4 as sizing agents Fiber was obtained. Component of binding energy (284.6 eV) belonging to (a) CHx, CC, C = C in C _1s core spectrum measured by X-ray photoelectron spectroscopy with excitation energy of 400 eV and photoelectron escape angle of 55 ° The ratio (a) / (b) of the height (cps) of the component (b) and the height (cps) of the component of the binding energy (286.1 eV) attributed to C—O is smaller than 0.50. Was out of range. Further, (I) / (II) indicating the ratio of (a) / (b) before and after acetone washing was 1, and it was found that there was no difference in composition between the inside and outside of the sizing layer. Moreover, although the initial adhesiveness measured by IFSS was sufficiently high, IFSS after storage in a wet environment decreased. The results are shown in Table 4.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. The 0 ° tensile strength utilization factor was good. The results are shown in Table 4.

(Comparative Examples 7 and 8)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon in the same manner as in Example 1 except that (A) component and (B) component are shown in Table 4 as sizing agents Fiber was obtained. Component of binding energy (284.6 eV) belonging to (a) CHx, CC, C = C in C _1s core spectrum measured by X-ray photoelectron spectroscopy with excitation energy of 400 eV and photoelectron escape angle of 55 ° The ratio (a) / (b) of the height (cps) of the component (b) and the height (cps) of the component of the binding energy (286.1 eV) attributed to C—O is greater than 0.90. Was out of range. Further, (I) / (II) indicating the ratio of (a) / (b) before and after acetone washing was 1, and it was found that there was no difference in composition between the inside and outside of the sizing layer. Moreover, the initial adhesiveness measured by IFSS was not sufficient. The results are shown in Table 4.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. The 0 ° tensile strength utilization factor was not a sufficient value. The results are shown in Table 4.

(Comparative Example 9)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.

-Step II: A step of attaching a sizing agent to carbon fibers (A) After preparing an aqueous solution of (A-4) as a component and applying it to carbon fibers surface-treated by a dipping method, at a temperature of 210 ° C A carbon fiber coated with a sizing agent was obtained by heat treatment for 75 seconds. The adhesion amount of the sizing agent was adjusted to 0.30 parts by mass with respect to 100 parts by mass of the surface-treated carbon fiber. Then, the water-dispersed emulsion which consists of 20 mass parts of (B-3), (C) component 20 mass parts, and 10 mass parts of emulsifiers as a (B) component was prepared. As component (C), 2 mol of an adduct of bisphenol A with 2 mol of ethylene oxide and 1.5 mol of maleic acid and 0.5 mol of sebacic acid, and polyoxyethylene (70 mol) styrenation as an emulsifier (5 Mol) cumylphenol was used. This sizing agent was applied to the carbon fiber coated with the component (A) by the dipping method, and then heat-treated at a temperature of 210 ° C. for 75 seconds to obtain a carbon fiber coated with the sizing agent. The adhesion amount of the sizing agent was adjusted to 1.0 mass% with respect to the sizing agent-coated carbon fiber. Component of binding energy (284.6 eV) belonging to (a) CHx, C—C, C = C of C _1s core spectrum measured by X-ray photoelectron spectroscopy with excitation energy of 400 eV and photoelectron escape angle of 55 ° The ratio (a) / (b) of the height (cps) of the component (b) and the height (cps) of the component of the binding energy (286.1 eV) attributed to C—O is greater than 0.90. Was out of range. In addition, (I) / (II) indicating the ratio of (a) / (b) before and after acetone washing was smaller than 0.6 and deviated from the scope of the present invention. Moreover, the initial adhesiveness measured by IFSS was not sufficient. The results are shown in Table 4.

Step III: Preparation, molding and evaluation of prepreg A prepreg was prepared, molded and evaluated in the same manner as in Example 1. The 0 ° tensile strength utilization factor was not a sufficient value. The results are shown in Table 4.

(Example 31)
The average particle diameter of the aqueous sizing agent solution used in Example 1 was measured with a particle size distribution meter. The average particle size was 290 nm, and it was found that the emulsion was stably present in water. The results are shown in Table 5.

(Examples 32 and 33)
The average particle size of the aqueous sizing agent solution used in Examples 3 and 11 was measured with a particle size distribution meter. The average particle sizes were 200 and 240 nm, respectively, and it was found that the emulsion was stably present in water. The results are shown in Table 5.

(Example 34)
The average particle size of the aqueous sizing agent solution used in Example 30 was measured with a particle size distribution meter. The average particle size was 540 nm and the emulsion was found to be slightly unstable in water. The results are shown in Table 5.

(Comparative Example 10)
The average particle size of the aqueous sizing agent solution used in Comparative Example 2 was measured with a particle size distribution meter. The average particle size was 230 nm, and it was found that the emulsion was stably present in water. The results are shown in Table 5.

(Comparative Example 11)
The average particle size of the aqueous sizing agent solution used in Comparative Example 3 was measured with a particle size distribution meter. The average particle size was 600 nm and the emulsion was found to be unstable in water. The results are shown in Table 5.

(Comparative Example 12)
The average particle size of the aqueous sizing agent solution used in Comparative Example 4 was measured with a particle size distribution meter. The average particle size was 240 nm, and it was found that the emulsion was stably present in water. The results are shown in Table 5.

(Comparative Example 13)
The average particle size of the aqueous sizing agent solution used in Comparative Example 7 was measured with a particle size distribution meter. The average particle size was 150 nm, and it was found that the emulsion was stably present in water. The results are shown in Table 5.

(Example 35)
The present embodiment includes the following steps I to V.

-Step I: Process for producing carbon fiber as raw material A copolymer composed of 99 mol% acrylonitrile and 1 mol% itaconic acid is spun and fired, the total number of filaments is 24,000, and the total fineness is 1,000. A carbon fiber having a tex, a specific gravity of 1.8, a strand tensile strength of 5.9 GPa, and a strand tensile elastic modulus of 295 GPa was obtained. Subsequently, the carbon fiber was subjected to an electrolytic surface treatment with an aqueous solution of ammonium hydrogen carbonate having a concentration of 0.1 mol / l as an electrolytic solution at an electric charge of 50 coulomb per gram of carbon fiber. The carbon fiber subjected to the electrolytic surface treatment was subsequently washed with water and dried in heated air at a temperature of 150 ° C. to obtain a carbon fiber as a raw material. At this time, the surface oxygen concentration O / C was 0.15, the surface carboxyl group concentration COOH / C was 0.005, and the surface hydroxyl group concentration COH / C was 0.018. The surface roughness (Ra) of the carbon fiber at this time was 3.0 nm. This was designated as carbon fiber A.

-Step II: Step of adhering sizing agent to carbon fiber (B) As component (B-3), 20 parts by mass, (C) 20 parts by mass of component and 10 parts by mass of emulsifier were prepared. Thereafter, 50 parts by mass of (A-2) as component (A) was mixed to prepare a sizing solution. As component (C), 2 mol of EO 2 mol adduct of bisphenol A, 1.5 mol of maleic acid and 0.5 mol of sebacic acid, polyoxyethylene (70 mol) as a emulsifier, styrenation (5 mol) Cumylphenol was used. The component (C) and the emulsifier are both aromatic compounds. After applying this sizing agent to the carbon fiber surface-treated by the dipping method, heat treatment was performed at a temperature of 210 ° C. for 75 seconds to obtain a carbon fiber coated with the sizing agent. The adhesion amount of the sizing agent was adjusted to 0.6% by mass with respect to the carbon fiber coated with the sizing agent. Following this, X-ray photoelectron spectroscopy measurements on the sizing agent surface were measured. As a result, it was confirmed that the composition of the sizing agent on the carbon fiber surface was as expected.

-Step III: Cutting step of carbon fiber coated with sizing agent The carbon fiber coated with the sizing agent obtained in Step II was cut into 1/4 inch with a cartridge cutter.

-Step IV: Extrusion process Using a TEX-30α type twin screw extruder (screw diameter 30 mm, L / D = 32), PPS resin pellets were supplied from the main hopper, and then The carbon fiber coated with the sizing agent cut in the previous step was supplied from the downstream side hopper, kneaded sufficiently at a barrel temperature of 320 ° C. and a rotation speed of 150 rpm, and further deaerated from the downstream vacuum vent. The supply was adjusted by a weight feeder so that the carbon fiber coated with the sizing agent was 10 parts by mass with respect to 90 parts by mass of the PPS resin pellets. The molten resin was discharged from a die port (diameter 5 mm), and the obtained strand was cooled and then cut with a cutter to obtain a pellet-shaped molding material.

-V step: injection molding step:
Using the J350EIII type injection molding machine manufactured by Nippon Steel Works, the pellet-shaped molding material obtained in the extrusion process was molded into a specimen for characteristic evaluation at a cylinder temperature of 330 ° C. and a mold temperature of 80 ° C. . The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 6. As a result, it was found that the bending strength (S1) before heat treatment was 228 MPa, and the mechanical properties were sufficiently high. Further, it was found that the ratio (S2 / S1) to the bending strength (S2) after the heat treatment was 0.81, and there was sufficient hot water resistance.

(Examples 36 to 40)
The present embodiment includes the following steps I to V.

Step I: Step of producing carbon fiber as raw material The same procedure as in Example 35 was performed.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was prepared in the same manner as in Example 35 except that the components (A) and (B) shown in Table 6 were used as the sizing agent. Obtained. Following this, X-ray photoelectron spectroscopy measurements on the sizing agent surface were measured. As a result, it was confirmed that the composition of the sizing agent on the carbon fiber surface was as expected.

Step III: Cutting process of carbon fiber coated with sizing agent The same procedure as in Example 35 was performed.

Step IV: Extrusion step Same as Example 35.

-V step: injection molding step:
In the same manner as in Example 35, a test piece for property evaluation was molded. The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 6. As a result, it was found that the bending strength (S1) before the heat treatment was sufficiently high. Moreover, it turned out that ratio (S2 / S1) with respect to the bending strength (S2) after heat processing is 0.75 or more, and there exists sufficient heat-and-water resistance.

(Comparative Example 14)
This comparative example includes the following steps I to V.

Step I: Step of producing carbon fiber as raw material The same procedure as in Example 35 was performed.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was prepared in the same manner as in Example 35 except that the components (A) and (B) shown in Table 6 were used as the sizing agent. Obtained. Following this, X-ray photoelectron spectroscopy measurements on the sizing agent surface were measured. As a result, the composition of the sizing agent on the carbon fiber surface was out of the scope of the present invention.

Step III: Cutting process of carbon fiber coated with sizing agent The same procedure as in Example 35 was performed.

Step IV: Extrusion step Same as Example 35.

-V step: injection molding step:
In the same manner as in Example 35, a test piece for property evaluation was molded. The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 6. As a result, it was found that the bending strength (S1) before heat treatment was 219 MPa, which was insufficient. Moreover, it turned out that ratio (S2 / S1) with respect to the bending strength (S2) after heat processing is 0.68, and hot water resistance is low.

(Comparative Example 15)
This comparative example includes the following steps I to V.

Step I: Step of producing carbon fiber as raw material The same procedure as in Example 35 was performed.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was prepared in the same manner as in Example 35 except that the components (A) and (B) shown in Table 6 were used as the sizing agent. Obtained. Following this, X-ray photoelectron spectroscopy measurements on the sizing agent surface were measured. As a result, the composition of the sizing agent on the carbon fiber surface was out of the scope of the present invention.

Step III: Cutting process of carbon fiber coated with sizing agent The same procedure as in Example 35 was performed.

Step IV: Extrusion step Same as Example 35.

-V step: injection molding step:
In the same manner as in Example 35, a test piece for property evaluation was molded. The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 6. As a result, it was found that the bending strength (S1) before heat treatment was 215 MPa, which was insufficient. Further, the ratio (S2 / S1) to the bending strength (S2) after the heat treatment was 0.88, and it was found that there was sufficient hot water resistance.

(Examples 41 to 46)
-Step I: Step of producing carbon fiber as raw material The same as in Example 35.

-Step II: Step of attaching sizing agent to carbon fiber The same as in Examples 35-40.

Step III: Cutting process of carbon fiber coated with sizing agent The same procedure as in Example 35 was performed.

-Step IV: Extrusion Step Using a steel mill TEX-30α type twin screw extruder (screw diameter 30 mm, L / D = 32), PC resin pellets were fed from the main hopper, and then Carbon fiber coated with the sizing agent cut in the previous step was supplied from the downstream side hopper, kneaded sufficiently at a barrel temperature of 300 ° C. and a rotation speed of 150 rpm, and further deaerated from a downstream vacuum vent. The supply was adjusted by a weight feeder so that the carbon fiber coated with the sizing agent was 8 parts by mass with respect to 92 parts by mass of the PC resin pellets. The molten resin was discharged from a die port (diameter 5 mm), and the obtained strand was cooled and then cut with a cutter to obtain a pellet-shaped molding material.

-V step: injection molding step:
Using the J350EIII type injection molding machine manufactured by Nippon Steel Works, the pellet-shaped molding material obtained in the extrusion process was molded into a specimen for characteristic evaluation at a cylinder temperature of 320 ° C. and a mold temperature of 70 ° C. . The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 7. As a result, it was found that the bending strength (S1) before the heat treatment was sufficiently high. It was also found that the ratio (S2 / S1) to the bending strength (S2) after the heat treatment was 0.75 or more, and there was sufficient hot water resistance.

(Comparative Example 16)
This comparative example includes the following steps I to V.

Step I: Step of producing carbon fiber as raw material The same procedure as in Example 35 was performed.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was prepared in the same manner as in Example 35 except that the components (A) and (B) shown in Table 7 were used as the sizing agent. Obtained. Following this, X-ray photoelectron spectroscopy measurements on the sizing agent surface were measured. As a result, the composition of the sizing agent on the carbon fiber surface was out of the scope of the present invention.

Step III: Cutting process of carbon fiber coated with sizing agent The same procedure as in Example 35 was performed.

Step IV: Extrusion step Same as Example 41.

-V step: injection molding step:
In the same manner as in Example 41, a test piece for property evaluation was molded. The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 7. As a result, it was found that the bending strength (S1) before heat treatment was 150 MPa, which was insufficient. Moreover, it turned out that ratio (S2 / S1) with respect to the bending strength (S2) after heat processing is 0.68, and hot water resistance is low.

(Comparative Example 17)
This comparative example includes the following steps I to V.

Step I: Step of producing carbon fiber as raw material The same procedure as in Example 35 was performed.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was prepared in the same manner as in Example 35 except that the components (A) and (B) shown in Table 7 were used as the sizing agent. Obtained. Following this, X-ray photoelectron spectroscopy measurements on the sizing agent surface were measured. As a result, the composition of the sizing agent on the carbon fiber surface was out of the scope of the present invention.
Step III: Cutting process of carbon fiber coated with sizing agent The same procedure as in Example 35 was performed.
Step IV: Extrusion step Same as Example 41.
-V step: injection molding step:
In the same manner as in Example 41, a test piece for property evaluation was molded. The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 7. As a result, it was found that the bending strength (S1) before the heat treatment was 145 MPa, which was insufficient. Further, it was found that the ratio (S2 / S1) to the bending strength (S2) after heat treatment was 0.80, and there was sufficient hot water resistance.

(Examples 47 to 52)
-Step I: Step of producing carbon fiber as raw material The same as in Example 35.

-Step II: Step of attaching sizing agent to carbon fiber The same as in Examples 35-40.

Step III: Cutting process of carbon fiber coated with sizing agent The same procedure as in Example 35 was performed.

-Step IV: Extrusion process Using a TEX-30α type twin screw extruder (screw diameter 30 mm, L / D = 32), Nippon Steel Works, Ltd., supplying PP resin pellets from the main hopper, Carbon fiber coated with the sizing agent cut in the previous step was supplied from the downstream side hopper, kneaded sufficiently at a barrel temperature of 230 ° C. and a rotation speed of 150 rpm, and further deaerated from a downstream vacuum vent. The supply was adjusted by a weight feeder so that the carbon fiber coated with the sizing agent was 20 parts by mass with respect to 80 parts by mass of the PP resin pellets. The molten resin was discharged from a die port (diameter 5 mm), and the obtained strand was cooled and then cut with a cutter to obtain a pellet-shaped molding material.

-V step: injection molding step:
Using the J350EIII type injection molding machine manufactured by Nippon Steel Works, the pellet-shaped molding material obtained in the extrusion process was molded into a specimen for characteristic evaluation at a cylinder temperature of 240 ° C. and a mold temperature of 60 ° C. . The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 8. As a result, it was found that the bending strength (S1) before the heat treatment was sufficiently high. It was also found that the ratio (S2 / S1) to the bending strength (S2) after the heat treatment was 0.75 or more, and there was sufficient hot water resistance.

(Comparative Example 18)
This comparative example includes the following steps I to V.

Step I: Step of producing carbon fiber as raw material The same procedure as in Example 35 was performed.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was prepared in the same manner as in Example 35 except that the components (A) and (B) shown in Table 8 were used as the sizing agent. Obtained. Following this, X-ray photoelectron spectroscopy measurements on the sizing agent surface were measured. As a result, the composition of the sizing agent on the carbon fiber surface was out of the scope of the present invention.

Step III: Cutting process of carbon fiber coated with sizing agent The same procedure as in Example 35 was performed.

-Step IV: Extrusion step Same as Example 47.

-V step: injection molding step:
In the same manner as in Example 47, a test piece for property evaluation was molded. The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 8. As a result, it was found that the bending strength (S1) before heat treatment was 97 MPa, which was insufficient. Further, it was found that the ratio (S2 / S1) to the bending strength (S2) after heat treatment was 0.89, and there was sufficient hot water resistance.

(Comparative Example 19)
This comparative example includes the following steps I to V.

Step I: Step of producing carbon fiber as raw material The same procedure as in Example 35 was performed.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was prepared in the same manner as in Example 35 except that the components (A) and (B) shown in Table 8 were used as the sizing agent. Obtained. Following this, X-ray photoelectron spectroscopy measurements on the sizing agent surface were measured. As a result, the composition of the sizing agent on the carbon fiber surface was out of the scope of the present invention.

Step III: Cutting process of carbon fiber coated with sizing agent The same procedure as in Example 35 was performed.

-Step IV: Extrusion step Same as Example 47.

-V step: injection molding step:
In the same manner as in Example 47, a test piece for property evaluation was molded. The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 8. As a result, it was found that the bending strength (S1) before the heat treatment was 95 MPa, which was insufficient. Further, it was found that the ratio (S2 / S1) to the bending strength (S2) after heat treatment was 0.98, and there was sufficient hot water resistance.

(Examples 53 to 58)
-Step I: Step of producing carbon fiber as raw material The same as in Example 35.

-Step II: Step of attaching sizing agent to carbon fiber The same as in Examples 35-40.

Step III: Cutting process of carbon fiber coated with sizing agent The same procedure as in Example 35 was performed.

-Step IV: Extrusion process Nippon Steel Works TEX-30α type twin screw extruder (screw diameter 30 mm, L / D = 32), PA66 resin (PA) pellets are supplied from the main hopper, Next, carbon fibers coated with the sizing agent cut in the previous step were supplied from the downstream side hopper, sufficiently kneaded at a barrel temperature of 280 ° C. and a rotation speed of 150 rpm, and further deaerated from a downstream vacuum vent. The supply was adjusted by a weight feeder so that the carbon fiber coated with the sizing agent was 30 parts by mass with respect to 70 parts by mass of the PA66 resin pellets. The molten resin was discharged from a die port (diameter 5 mm), and the obtained strand was cooled and then cut with a cutter to obtain a pellet-shaped molding material.

-V step: injection molding step:
Using the J350EIII type injection molding machine manufactured by Nippon Steel Works, the pellet-shaped molding material obtained in the extrusion process was molded into a specimen for characteristic evaluation at a cylinder temperature of 300 ° C. and a mold temperature of 70 ° C. . The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 9. As a result, it was found that the bending strength (S1) before the heat treatment was sufficiently high. Moreover, it turned out that ratio (S2 / S1) with respect to the bending strength (S2) after heat processing is 0.75 or less, and hot water resistance is low.

(Comparative Example 20)
This comparative example includes the following steps I to V.

Step I: Step of producing carbon fiber as raw material The same procedure as in Example 35 was performed.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was prepared in the same manner as in Example 35 except that the components (A) and (B) shown in Table 9 were used as the sizing agent. Obtained. Following this, X-ray photoelectron spectroscopy measurements on the sizing agent surface were measured. As a result, the composition of the sizing agent on the carbon fiber surface was out of the scope of the present invention.

Step III: Cutting process of carbon fiber coated with sizing agent The same procedure as in Example 35 was performed.

Step IV: Extrusion step Same as Example 53.

-V step: injection molding step:
In the same manner as in Example 53, a test piece for property evaluation was molded. The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 9. As a result, it was found that the bending strength (S1) before the heat treatment was 340 MPa, which was sufficiently high. Moreover, it turned out that ratio (S2 / S1) with respect to the bending strength (S2) after heat processing is 0.52, and hot water resistance is inadequate.

(Comparative Example 21)
This comparative example includes the following steps I to V.

Step I: Step of producing carbon fiber as raw material The same procedure as in Example 35 was performed.

Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was prepared in the same manner as in Example 35 except that the components (A) and (B) shown in Table 9 were used as the sizing agent. Obtained. Following this, X-ray photoelectron spectroscopy measurements on the sizing agent surface were measured. As a result, the composition of the sizing agent on the carbon fiber surface was out of the scope of the present invention.

Step III: Cutting process of carbon fiber coated with sizing agent The same procedure as in Example 35 was performed.

Step IV: Extrusion step Same as Example 53.

-V step: injection molding step:
In the same manner as in Example 53, a test piece for property evaluation was molded. The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained test piece for property evaluation was evaluated according to the above-described injection molded product evaluation method. The results are shown in Table 9. As a result, it was found that the bending strength (S1) before heat treatment was 320 MPa, which was insufficient. Moreover, it turned out that ratio (S2 / S1) with respect to the bending strength (S2) after heat processing is 0.67, and hot water resistance is inadequate.

Claims (13)

At least ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, trimethylene glycol, 1,2-butanediol, 1,3 -Consisting of butanediol, 1,4-butanediol, 2,3-butanediol, polybutylene glycol, 1,5-pentanediol, glycerol, diglycerol, polyglycerol, trimethylolpropane, pentaerythritol, sorbitol, and arabitol Glycidyl ether type epoxy compound obtained by reaction of at least one selected from the group with epichlorohydrin A certain water-soluble epoxy compound (A) and non-water-soluble epoxy compound (B) sizing agent coated carbon fibers coated in carbon fiber sizing agent comprising,
Bond energy (284.6 eV) attributed to (a) CHx, C—C, C = C in the C1s core spectrum measured at a photoelectron escape angle of 55 ° by X-ray photoelectron spectroscopy using 400 eV X-rays (B) obtained from the ratio (a) / (b) between the height (cps) of the component of (b) and the height (cps) of the component (286.1 eV) attributed to C—O (I ) And (II) satisfying the relationship of (III), a sizing agent-coated carbon fiber.
(I) The value of (a) / (b) on the surface of the sizing agent-coated carbon fiber (II) The sizing agent-coated carbon fiber is sonicated in an acetone solvent, so that the sizing agent adhesion amount is 0.09. The value of (a) / (b) (III) 0.50 ≦ (I) ≦ 0.90, 0.6 <(II) / () on the surface of the sizing agent-coated carbon fiber washed to ˜0.20% by mass I) <1.0 Water-soluble epoxy compound (A) epoxy value 2.0 meq / g or more, a hydroxyl value is 2.0~5.0meq / g, and two or more epoxy groups in the molecule, according to claim 1 Sizing agent coated carbon fiber. The sizing agent-coated carbon fiber according to claim 1 or 2 , wherein the water-insoluble epoxy compound (B) is an aromatic epoxy compound (B1) having one or more aromatic rings in the molecule. The sizing agent-coated carbon fiber according to claim 3 , wherein the aromatic epoxy compound (B1) is a bisphenol A type epoxy compound or a bisphenol F type epoxy compound. The sizing agent application | coating in any one of Claims 1-4 whose mass ratio of the water-soluble epoxy compound (A) and the water-insoluble epoxy compound (B) in the said sizing agent is 52 / 48-80 / 20. Carbon fiber. The surface carboxyl group concentration COOH / C of the carbon fiber measured by chemical modification X-ray photoelectron spectroscopy is 0.003 to 0.015, and the surface hydroxyl group concentration COH / C is 0.001 to 0.050. Sizing agent application | coating carbon fiber in any one of 1-5 . A method for producing a sizing agent-coated carbon fiber in which a sizing agent comprising a water-soluble epoxy compound (A) and a water-insoluble epoxy compound (B) is applied to carbon fiber, and after applying the sizing agent to the carbon fiber, A method for producing a sizing agent-coated carbon fiber according to any one of claims 1 to 6, wherein the sizing agent-coated carbon fiber according to any one of claims 1 to 6 is produced by heat treatment at a temperature range of 160 to 260 ° C for 30 to 600 seconds. The sizing according to claim 7, wherein a sizing agent-containing liquid in which an aqueous emulsion liquid containing at least a water-insoluble epoxy compound (B) is present in an aqueous solution containing at least the water-soluble epoxy compound (A) is applied to the carbon fiber. A method for producing an agent-coated carbon fiber. The sizing agent-containing liquid obtained by preparing a water-soluble epoxy compound (A) in an aqueous solution of 0.1 to 50% by mass and then mixing it with an aqueous emulsion (B) solution having a concentration of 0.1 to 50% by mass. The manufacturing method of the sizing agent application | coating carbon fiber of Claim 8 apply | coated to the said carbon fiber. The sizing agent-coated carbon fiber according to any one of claims 7 to 9 , wherein a particle size of the aqueous emulsion containing at least the water-insoluble epoxy compound (B) measured by a particle size distribution meter is 100 to 600 nanometers. Production method. Sizing agent applying carbon fiber as described in any one of claims 1 to 6, and carbon fiber-reinforced thermoplastic resin composition comprising a thermoplastic resin. The molded body of the carbon fiber reinforced thermoplastic resin composition has a ratio (S2) of bending strength (S1) before being immersed in hot water at 80 ° C. and bending strength (S2) after being immersed in hot water at 80 ° C. for 1000 hours. / S1) is 0.75 or more, The carbon fiber reinforced thermoplastic resin composition of Claim 11 characterized by the above-mentioned. The carbon fiber reinforced thermoplastic resin composition according to claim 11 or 12, wherein the thermoplastic resin is at least one selected from the group consisting of a polyarylene sulfide resin, a polycarbonate resin, and a polyolefin resin.