Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
  • D06M13/10—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing oxygen
  • D06M13/165—Ethers
  • D06M13/17—Polyoxyalkyleneglycol ethers
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
  • D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
  • D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
  • D06M15/37—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M15/53—Polyethers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F11/00—Chemical after-treatment of artificial filaments or the like during manufacture
  • D01F11/10—Chemical after-treatment of artificial filaments or the like during manufacture of carbon
  • D01F11/14—Chemical after-treatment of artificial filaments or the like during manufacture of carbon with organic compounds, e.g. macromolecular compounds
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F11/00—Chemical after-treatment of artificial filaments or the like during manufacture
  • D01F11/10—Chemical after-treatment of artificial filaments or the like during manufacture of carbon
  • D01F11/16—Chemical after-treatment of artificial filaments or the like during manufacture of carbon by physicochemical methods
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
  • D06M13/02—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with hydrocarbons
  • D06M13/03—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with hydrocarbons with unsaturated hydrocarbons, e.g. alkenes, or alkynes
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
  • D06M13/10—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing oxygen
  • D06M13/144—Alcohols; Metal alcoholates
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
  • D06M13/10—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing oxygen
  • D06M13/144—Alcohols; Metal alcoholates
  • D06M13/148—Polyalcohols, e.g. glycerol or glucose
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M23/00—Treatment of fibres, threads, yarns, fabrics or fibrous goods made from such materials, characterised by the process
  • D06M23/10—Processes in which the treating agent is dissolved or dispersed in organic solvents; Processes for the recovery of organic solvents thereof
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M2101/00—Chemical constitution of the fibres, threads, yarns, fabrics or fibrous goods made from such materials, to be treated
  • D06M2101/40—Fibres of carbon
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M2200/00—Functionality of the treatment composition and/or properties imparted to the textile material
  • D06M2200/40—Reduced friction resistance, lubricant properties; Sizing compositions
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2101/00—Inorganic fibres
  • D10B2101/10—Inorganic fibres based on non-oxides other than metals
  • D10B2101/12—Carbon; Pitch

Definitions

• the present invention relates to a carbon fiber bundle containing a sizing agent and a method for producing a carbon fiber bundle containing a sizing agent.
• Carbon fiber is light in weight and has excellent strength and elastic modulus. Therefore, it is used as a composite material in combination with various matrix resins for aircraft parts, spacecraft parts, automobile parts, ship parts, civil engineering and construction materials, sporting goods, and the like.
• a representative form of a composite material using carbon fibers is a molded article obtained by press-molding a preform obtained by laminating prepregs (a molding method in which defoaming is performed under pressure and shaping is performed). This prepreg is generally produced by impregnating a carbon fiber substrate in which continuous carbon fiber bundles are arranged in one direction with a resin.
• Composite materials using discontinuous carbon fibers (chopped, web, etc.) have been proposed, which have excellent conformability to complex shapes and can be molded in a short time. In terms of stability, prepreg is superior in practical performance as a structural material.
• thermoplastic resin slurry in which a powdery thermoplastic resin is dispersed with a surfactant is passed through to prepare a carbon fiber tape that holds the powdery thermoplastic resin, and the thermoplastic resin is made thermoplastic by heat and pressure.
• a method of manufacturing by impregnating the inside of the carbon fiber tape with a resin can be mentioned.
• Patent Document 1 and 2 In order to take advantage of the excellent properties of carbon fiber after composite processing, it is important to have excellent handleability during carbon fiber processing and reduce fuzz wrapping and breakage due to wrapping. Carbon fiber bundles to which no sizing agent is applied lack bundling properties and generate a large amount of fluff. Therefore, in order to improve the handleability of carbon fibers, a method of applying a sizing agent to the carbon fiber bundles and imparting a scratch-resistant coating film on the surface of the carbon fibers is usually performed (Patent Document 1 and 2).
• the sizing agent applied to the carbon fiber is easily decomposed by heat, it will be heated to a high temperature when molding a carbon fiber reinforced composite material using a prepreg impregnated with a matrix resin with a high molding temperature such as a super engineering plastic. Since the sizing agent is decomposed or volatilized and the amount of gas in the matrix resin can be reduced, voids inside the molding can be suppressed (see Patent Document 3).
• the carbon fiber surface is usually subjected to an oxidation treatment such as vapor phase oxidation or liquid phase oxidation in order to improve the adhesiveness between the carbon fiber and the matrix resin.
• an oxidation treatment such as vapor phase oxidation or liquid phase oxidation in order to improve the adhesiveness between the carbon fiber and the matrix resin.
• the present invention has been made in view of the above.
• a carbon fiber reinforced composite with extremely few voids and reflecting the surface characteristics of carbon fibers, with a high heat-resistant thermoplastic resin as the matrix resin.
• An object of the present invention is to provide a carbon fiber bundle containing a sizing agent suitable for producing a prepreg from which a material is obtained, and a method for producing the same.
• the present invention for solving the above problems is a carbon fiber bundle containing carbon fibers and a sizing agent that satisfies all of the following (i) to (iv). (i) Satisfies either (a) or (b) below.
• the ratio of polyalkylene glycol structure in the total weight of the sizing agent is 60% by weight or more
• the sizing agent contains an acetylene structure, and the ratio of the polyalkylene glycol structure in the total weight of the sizing agent is 20% by weight or more
• the thermal weight loss rate A determined under the following measurement conditions is 5.0% or less.
• a thermal weight loss rate B determined under the following measurement conditions is 11.0% or more.
• a thermal weight loss rate C determined under the following measurement conditions is 90.0% or more.
• Thermal weight loss rate A> The sizing agent is weighed in the range of 10 ⁇ 2 mg, and the weighed mass is defined as W A0 (mg)). Medium, the temperature is increased from 30 ° C. at a rate of 10 ° C./min, and the mass of the sizing agent when reaching 140 ° C. is measured to be W A1 (mg), and the thermal weight loss rate A is calculated from the following formula (A). calculate.
• Thermal weight loss rate A (%) ⁇ (W A0 ⁇ W A1 )/W A0 ⁇ 100 (A) ⁇ Thermal weight loss rate B> Weigh the sizing agent in the range of 10 ⁇ 2 mg (this weighed mass is W B0 (mg)), and use a thermogravimetry device to measure 200 ml (volume at 1 atm, 25 ° C.) / min of nitrogen In an air stream, the temperature is raised from 30° C. at a rate of 10° C./min, and the mass of the sizing agent when reaching 250° C. is measured to obtain W B1 (mg), and the thermal weight loss rate B is calculated from the following formula (B).
• the method for producing a carbon fiber bundle containing a sizing agent of the present invention is characterized by having a drying step of drying the carbon fiber bundle containing the sizing agent after passing through the step of incorporating the sizing agent into the carbon fiber. do.
• the carbon fiber bundle containing the sizing agent even when the carbon fiber bundle containing the sizing agent is excellent in handling, voids can be eliminated by containing the sizing agent, which is easily thermally decomposed at low temperatures due to its good thermal decomposability, in the carbon fiber. It is possible to obtain a carbon fiber bundle containing a sizing agent that is particularly suitable for combination with a thermoplastic resin, which can provide a carbon fiber reinforced composite material that reflects the surface properties of carbon fibers.
• the sizing agent-containing carbon fiber bundle of the present invention is a carbon fiber bundle containing carbon fibers and a sizing agent that satisfies all of the following (i) to (iv). (i) Satisfies either (a) or (b) below.
• the ratio of the polyalkylene glycol structure in the total weight of the sizing agent is 60% by weight or more
• the sizing agent contains an acetylene structure, and the ratio of the polyalkylene glycol structure in the total weight of the sizing agent is 20% by weight or more
• the thermal weight loss rate A determined under the following measurement conditions is 5.0% or less.
• a thermal weight loss rate B determined under the following measurement conditions is 11.0% or more.
• a thermal weight loss rate C determined under the following measurement conditions is 90.0% or more.
• Thermal weight loss rate A> The sizing agent was weighed in the range of 10 ⁇ 2 mg (this weighed mass is W A0 (mg)), and a thermogravimetry device was used to measure 200 ml (volume at 1 atm, 25 ° C.) / min nitrogen In an air stream, the temperature was raised from 30°C at a rate of 10°C/min, and the mass of the sizing agent when reaching 140°C was measured (this measured mass is W A1 (mg)), and the following formula Calculate the thermal weight loss rate A from (A).
• Thermal weight loss rate A (%) ⁇ (W A0 ⁇ W A1 )/W A0 ⁇ 100 (A) ⁇ Thermal weight loss rate B> Weigh the sizing agent in the range of 10 ⁇ 2 mg (this weighed mass is W B0 (mg)), and use a thermogravimetry device to measure 200 ml (volume at 1 atm, 25 ° C.) / min of nitrogen The temperature of the sizing agent is increased from 30°C at a rate of 10°C/min in an air stream, and the mass of the sizing agent when reaching 250°C is measured (this measured mass is W B1 (mg)), and the following formula is obtained: The thermal weight loss rate B is calculated from (B).
• the sizing agent constituting the present invention must satisfy either (a) or (b) below.
• (a) The ratio of polyalkylene glycol structure in the total weight of the sizing agent is 60% by weight or more
• the sizing agent contains an acetylene structure, and the ratio of the polyalkylene glycol structure in the total weight of the sizing agent is 20% by weight or more .
• the polyalkylene glycol structure is the structure of the following general formula (1).
• R is a hydrogen atom or a methyl group.
• n is an integer from 2 to 20;
• a carbon fiber bundle containing a sizing agent with a controlled proportion of a polyalkylene glycol structure thermally decomposes well without reacting with the surface of the carbon fiber during thermal decomposition. As a result, the amount of the sizing agent remaining in the carbon fiber bundle is reduced, making it easier to maintain the original carbon fiber surface condition.
• R is a hydrogen atom or a methyl group, preferably a hydrogen atom from the viewpoint of water solubility.
• n is an integer of 2 to 20, preferably smaller, more preferably 5 or less, even more preferably 3 or less, from the viewpoint of lowering the molecular weight and improving the thermal decomposability. When n is an integer of 21 or more, the molecular weight becomes large and the thermal decomposability is lowered.
• Examples of sizing agents having a structure represented by general formula (1) include polyethylene glycol, acetylene glycol, polyoxyethylene alkyl ethers such as polyoxyethylene dodecyl ether, polyoxyethylene oleyl ether, and polyoxyethylene stearyl ether, propylene Glycols, polyoxyethylene polyoxypropylene glycols and polyoxyethylene alkylphenyl ethers can be mentioned. Each one can be used alone or in combination of two or more.
• the acetylene structure is a structure with a triple bond between carbon and carbon.
• Sizing agents containing an acetylene structure include acetylene alcohol and acetylene glycol.
• the above sizing agent may be of one kind, or may be a mixture of two or more sizing agents.
• the ratio of the polyalkylene glycol structure to the total weight of the sizing agent is preferably 80% by mass or more, the higher the ratio of the polyalkylene glycol structure, the more preferably 85% by mass. If the ratio of the polyalkylene glycol structure is less than 60% by mass in the total amount of the sizing agent, the probability of contact with the sizing agent that hardly reacts with the surface functional groups of the carbon fibers decreases, the heat resistance increases, and the thermal decomposition becomes difficult.
• the proportion of polyalkylene glycol structures is about 83% by weight ((106-18)/106 ⁇ 100 (Note: atomic weights below the decimal point are omitted)), and the ratio of the polyalkylene glycol structure when it is only triethylene glycol (HO(CH 2 CH 2 O) 3 H) is about 88% by mass (( 150-18)/150 ⁇ 100 (note: atomic weights below the decimal point are omitted)).
• the ratio of the polyalkylene glycol structure to the total mass of the sizing agent must be 20% by mass or more.
• the acetylene structure When the acetylene structure is included, the acetylene structure has a triple bond in the structure, which makes the compound more linear and reduces entanglement interactions. Therefore, when the ratio of the polyalkylene glycol structure is 20% by mass or more, good thermal decomposability is exhibited. If the content is less than 20% by mass, the proportion of acetylene structure increases, which increases heat resistance and makes thermal decomposition difficult.
• the ratio of the polyalkylene glycol structure to the total mass of the sizing agent is more preferably 50% by mass or more.
• the sizing agent is only bis(1-hydroxyethyl)acetylene ( CH CH(OH)CCCH(OH)CH)
• the proportion of acetylene structures is about 21% by mass (24/ 114 ⁇ 100 (note: atomic weights below the decimal point are omitted)).
• the ratio of the polyalkylene glycol structure and the ratio of the acetylene structure in the total sizing agent contained in the carbon fiber can be calculated from the structural formula if the structural formula of the sizing agent is known. If it is unknown, the sizing agent can be extracted from the carbon fiber bundle containing the sizing agent, the structure can be identified by a known method such as proton NMR, carbon NMR, mass spectrometry, TOF-SIMS, and the ratio can be calculated. If there are multiple components, separate them using a column for evaluation. An example of extraction conditions is shown below.
• the sizing agent contained in the carbon fiber bundle contains an epoxy group, an amino group, or an oxazoline group as a structure other than the polyalkylene glycol structure, it will react with the surface functional groups of the carbon fiber, improving heat resistance and causing thermal decomposition. become difficult. Therefore, the sizing agent containing an epoxy group, an amino group, or an oxazoline group is preferably contained in an amount of 30% by mass or less based on the total mass of the sizing agent, and is preferably substantially absent. “Substantially free” means less than 1% by mass in 100% by mass of the sizing agent.
• the sizing agent on the carbon fiber bundle contains a sizing agent containing an epoxy group, amino group, or oxazoline group can be calculated from the structural formula if the structural formula of the sizing agent is known. If it is unknown, the sizing agent can be extracted from the carbon fiber bundle containing the sizing agent, the structure can be identified by a known method such as proton NMR, carbon NMR, mass spectrometry, TOF-SIMS, and the ratio can be calculated. When there are multiple components, the structure can be identified and the ratio can be calculated by adding an operation of fractionating using a column and performing evaluation.
• the sizing agent that constitutes the present invention must have a thermal weight loss rate A of 5.0% or less, which is determined under the following measurement conditions.
• thermal weight loss rate A is 5.0% or less, it is possible to suppress thermal decomposition and volatilization of the sizing agent when attaching the sizing agent to untreated carbon fibers. Therefore, a carbon fiber bundle containing a sizing agent is obtained which is less fuzzy due to mechanical friction such as fiber opening and is excellent in handleability.
• the sizing agent contains many components that increase the thermal weight loss rate A.
• Such a component that increases the thermal weight loss rate A has a small molecular weight and reduces the force of adhesion to the carbon fiber, so the larger the thermal weight loss rate A, the less likely it is to adhere to the carbon fiber, resulting in poor handleability Carbon containing a sizing agent Become a fiber bundle.
• the thermal weight loss rate A is preferably 3.0% or less, more preferably 1.0% or less.
• the value of the thermal weight loss rate A is preferably as small as possible, and is particularly preferably 0%. That is, the lower limit of the thermal weight loss rate A is preferably 0%.
• the sizing agent that constitutes the present invention must have a thermal weight loss rate B of 11.0% or more, which is determined under the following measurement conditions.
• the heat loss rate B is 11.0% or more, in the step of heating the carbon fiber bundle containing the sizing agent at a low temperature, most of the generation of gas due to thermal decomposition or volatilization of the sizing agent is completed, and the carbon fiber reinforced composite is produced. removed from the material. For this reason, voids are less likely to remain, and a good-quality molded product (carbon fiber reinforced composite material) capable of exhibiting the surface characteristics of the original carbon fiber can be obtained.
• the sizing agent will contain many components that reduce the thermal weight loss rate B. Since such a component that reduces the thermal loss rate B has a large molecular weight and easily coats the carbon fiber surface, the smaller the thermal loss rate B, the more the carbon fiber bundle surface after heat treatment is different from the original carbon fiber surface. It becomes a carbon fiber bundle containing a sizing agent that is easy to use.
• the thermal weight loss rate B is preferably 30.0% or more, more preferably 60.0% or more, and even more preferably 90.0% or more.
• the value of the thermal weight loss rate B is preferably as large as possible, and is particularly preferably 100.0%. That is, the upper limit of the thermal weight loss rate B is preferably 100.0%.
• the sizing agent that constitutes the present invention must have a thermal weight loss rate C of 90.0% or more, which is determined under the following measurement conditions.
• the heat loss rate C is 90.0% or more, most of the generation of gas due to decomposition or volatilization of the sizing agent is completed at the stage of completing the heating of the carbon fiber bundle containing the sizing agent, and the carbon fiber reinforced composite material is produced. removed from Therefore, voids are less likely to remain, and a carbon fiber reinforced composite material of good quality can be obtained.
• the sizing agent will contain many components that reduce the thermal weight loss rate C. Since such a component that reduces the thermal weight loss rate C has high heat resistance in air and tends to become a residue on the surface of the carbon fiber, the smaller the thermal weight loss rate C, the more the surface of the carbon fiber bundle after heat treatment is. The result is a carbon fiber bundle containing a sizing agent that tends to make the fibers different from the surface.
• the thermal weight loss rate C is 90.0% or more, more preferably 95.0% or more, and even more preferably 99.0% or more.
• the value of the thermal weight loss rate C is preferably as large as possible, and is particularly preferably 100.0%. That is, the upper limit of the thermal weight loss rate C is preferably 100.0%.
• thermal weight loss rate A, thermal weight loss rate B, and thermal weight loss rate C can be controlled by changing the element contained in the sizing agent, the type of partial structure, and the number average molecular weight Mn described later.
• thermal weight loss rate A, the thermal weight loss rate B, and the thermal weight loss rate C are the numerical values obtained by evaluating the sizing agent and the numerical values obtained by evaluating the sizing agent extracted from the carbon fiber bundle containing the sizing agent under the following extraction conditions. No difference was observed.
• the sizing agent constituting the present invention preferably has a number average molecular weight Mn of 120 or more and less than 300.
• the above number average molecular weight Mn is measured by a gel permeation chromatography (hereinafter abbreviated as GPC) method, and is obtained using polystyrene as a standard substance.
• GPC gel permeation chromatography
• the Mn is less than 300, the molecular chain is shortened and the thermal decomposability is improved, so thermal decomposition can be performed at a lower temperature in a shorter time. 250 or less is more preferable, and 200 or less is even more preferable.
• in terms of imparting the sizing agent by making it 120 or more, it is possible to suppress volatilization or thermal decomposition of the sizing agent when it is contained in untreated carbon fibers. 135 or more is more preferable.
• the number average molecular weight Mn of the sizing agent on the carbon fiber bundle containing the sizing agent can be confirmed by extracting the sizing agent from the carbon fiber bundle containing the sizing agent by the above extraction method and performing GPC evaluation.
• the number average molecular weight of the sizing agent can be measured by a known method using GPC using polystyrene as a standard substance. In the present invention, the following conditions are adopted as measurement conditions for GPC.
• Measuring device manufactured by Shimadzu Corporation Column used: TSKgel HXL-L + TSKgel ⁇ -3000 manufactured by TOSOH BIOSCIENCE Eluent: Dimethylformamide 0.01 mol/L lithium bromide solution Standard material: Polystyrene (manufactured by Tosoh Corporation) Detector: Suggestive refractometer (manufactured by Shimadzu Corporation).
• the measured value for the mixture thereof is taken as the number average molecular weight Mn.
• the sizing agent used in the present invention preferably does not substantially contain aromatic rings.
• a structure containing an aromatic ring such as bisphenol A or benzene has high heat resistance, so if it is contained in a sizing agent, the thermal decomposability is lowered.
• “Substantially free” means less than 1% by mass in 100% by mass of the sizing agent.
• the ratio of the aromatic ring contained in the sizing agent on the carbon fiber bundle containing the sizing agent can be confirmed from the structural formula. If it is unknown, the sizing agent can be extracted from the carbon fiber bundle containing the sizing agent, the structure can be identified by a known method such as proton NMR, carbon NMR, mass spectrometry, TOF-SIMS, and the ratio can be calculated. When there are multiple components, the structure can be identified and the ratio can be calculated by adding an operation of fractionating using a column and performing evaluation.
• the sizing agent content of the carbon fiber bundle containing the sizing agent constituting the present invention is preferably 0.3% by mass or more and 1.2% by mass or less in 100% by mass of the carbon fiber bundle containing the sizing agent. .
• the total amount of the plurality of sizing agents is defined as the sizing agent content of the carbon fiber bundle.
• the adhesion amount is more preferably 0.4% by mass or more, more preferably 0.5% by mass or more.
• the sizing agent content is more preferably 1.0% by mass or less, and even more preferably 0.8% by mass or less.
• the sizing agent-containing carbon fiber bundle that constitutes the present invention is obtained by subjecting the carbon fiber bundle after heating at 250° C. for 20 seconds in an oxidizing atmosphere to X-ray photoelectron spectroscopy using AlK ⁇ as an X-ray source, with a photoelectron escape angle of 45°.
• the ratio of the photoelectron intensity (a) (cps) (photoelectron intensity (b)/photoelectron intensity (a)) is preferably 0.2 or more and 0.8 or less.
• the C 1S core spectrum of the carbon fiber surface measured by X-ray photoelectron spectroscopy shows multiple carbon atoms with different bond energies. obtained as a composite peak of sub-peaks.
• the binding energy of 286.1 eV in the C 1S core spectrum is the binding energy at the central position of the sub-peak whose binding state is attributed to CO.
• the photoelectron intensity ratio (b)/(a) between the photoelectron intensity (a) (cps) detected at a binding energy of 284.6 eV and the photoelectron intensity (b) (cps) detected at a binding energy of 286.1 eV represents the ratio of carbon atoms having CO bonds on the carbon fiber surface, and the smaller the photoelectron intensity ratio (b)/(a), the less the carbon atoms having CO bonds.
• the photoelectron intensity ratio (b)/(a) on the carbon fiber surface is 0.8 or less, the amount of the sizing agent having a CO bond remaining on the carbon fiber surface is extremely small, which is a preferable range.
• it is 0.2 or more the surface functional groups of the original carbon fiber remain, and the surface physical properties can be reflected in the matrix resin. In particular, 0.3 or more is a more preferable range.
• an oxidizing atmosphere is an atmosphere containing many oxidizing gases (oxygen, ozone, etc.), and air is preferable from the viewpoint of handling.
• the carbon fiber bundle containing the sizing agent can be heated at 250°C for 20 seconds according to the following procedure.
• a carbon fiber bundle containing a sizing agent is introduced into a heated air atmosphere via a roller to thermally decompose the sizing agent.
• the carbon fiber bundle containing the sizing agent installed in the unwinding step is passed through the heating furnace via the free roller before the heating furnace and the free roller after the heating furnace, and is wound in the winding step.
• the unwinding tension from the creel was set to 800 g, the process speed was set to 6 m/min, and the section in the heating furnace at 250° C. was adjusted to 2 m so that the heating time was set to 20 seconds.
• the photoelectron intensity ratio (b)/(a) on the carbon fiber surface and the sizing agent content in the carbon fiber bundle can be measured. to obtain the content after heat treatment at
• the carbon fiber bundle containing the sizing agent of the present invention can have a sizing agent content of 0.02% by mass or more and 0.1% by mass or less after heat treatment at 250°C for 20 seconds in an oxidizing atmosphere.
• the total amount of the plurality of sizing agents is defined as the sizing agent content of the carbon fiber bundle.
• the content of the sizing agent after heat treatment at 250° C. for 20 seconds in an oxidizing atmosphere is 0.1% by mass or less, most of the generation of gas due to thermal decomposition or volatilization of the sizing agent is completed, and the carbon fiber reinforced composite material can be obtained. removed from For this reason, voids are less likely to remain, and a molded product (carbon fiber reinforced composite material) of good quality reflecting the surface characteristics of the original carbon fiber can be obtained.
• the sizing agent content is more preferably less than 0.08% by mass, still more preferably less than 0.06% by mass, and particularly preferably 0.04% by mass or less.
• a sizing agent content of 0.02% by mass or more after heat treatment at 250°C for 20 seconds in an oxidizing atmosphere is a preferable range because the surface functional groups of the original carbon fiber are maintained.
• the amount of oxygen atoms present on the surface of the carbon fiber before application of the sizing agent is not particularly limited.
• the surface oxygen concentration (functional group content, O/C) of the carbon fiber is preferably 0.11 or more and 0.25 or less, more preferably 0.15 or more and 0.20 or less. If the amount of surface functional groups on the carbon fiber is too small, the adhesion between the carbon fiber and the matrix resin tends to be low. Since the groups are easily decomposed, there is a large difference in the amount of functional groups before and after processing, and it tends to be difficult to reflect the characteristics of the original carbon fiber.
• the carbon fiber used in the present invention before application of a sizing agent preferably has a fiber-to-fiber friction coefficient of 0.25 or more and 0.43 or less. If it is 0.25 or more, force is likely to be applied between the single fibers, and bundling properties are likely to be improved. 0.28 or more is more preferable, and 0.30 or more is even more preferable. If it is 0.43 or less, the frictional force between the single yarns in the carbon fiber bundle is reduced, so fluff caused by friction when the carbon fiber bundle is pulled out from the bobbin is reduced. 0.39 or less is more preferable, and 0.35 or less is even more preferable.
• the fiber-to-fiber friction coefficient can be controlled by the roughness of the carbon fiber surface, the type and amount of surface treatment, and the like.
• the carbon fiber used in the present invention is not particularly limited, but polyacrylonitrile-based carbon fiber is preferably used from the viewpoint of mechanical properties.
• the polyacrylonitrile-based carbon fiber bundle used in the present invention is obtained by subjecting a carbon fiber precursor fiber made of a polyacrylonitrile-based polymer to a flameproof treatment at a maximum temperature of 200 to 300 ° C. in an oxidizing atmosphere, and then in an inert atmosphere. , pre-carbonization at a maximum temperature of 500-1200° C., followed by carbonization at a maximum temperature of 1200-2000° C. in an inert atmosphere.
• oxygen-containing functional groups to the surface by subjecting the carbon fiber bundle to oxidation treatment.
• Gas-phase oxidation, liquid-phase oxidation, and liquid-phase electrolytic oxidation are used as the oxidation treatment method.
• Liquid-phase electrolytic oxidation is preferably used from the viewpoint of high productivity and uniform treatment.
• the electrolytic solution used in the liquid-phase electrolytic oxidation includes an acidic electrolytic solution and an alkaline electrolytic solution.
• acidic electrolytes 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.
• sulfuric acid and nitric acid which are strongly acidic, are preferably used.
• alkaline electrolytes 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 carbonates such as sodium hydrogencarbonate, potassium hydrogencarbonate, magnesium hydrogencarbonate, calcium hydrogencarbonate, barium hydrogencarbonate and ammonium hydrogencarbonate, ammonia, tetraalkylammonium hydroxide and an aqueous solution of hydrazine.
• hydroxides such as sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide and barium hydroxide
• Aqueous solutions of carbonates such as barium carbonate and ammonium carbonate
• aqueous solutions of carbonates such as sodium hydrogencarbonate, potassium hydrogencarbonate, magnesium hydrogencarbonate, calcium hydrogencarbonate
• the sizing agent is preferably diluted with a solvent and used as a uniform solution.
• solvents include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, dimethylformamide, and dimethylacetamide. Therefore, water is preferably used.
• Examples of means for applying the sizing agent include a method of immersing the carbon fiber bundle in the sizing agent solution through a roller, a method of contacting the carbon fiber bundle with a roller to which the sizing agent solution is attached, and a method of spraying the sizing agent solution.
• a method of spraying the carbon fiber bundle in the form of a sizing agent a method of immersing the carbon fiber in a solution of the sizing agent via a roller is preferably used in producing the carbon fiber bundle containing the sizing agent of the present invention.
• the sizing agent may be applied by either a batch method or a continuous method, but the continuous method is preferably used because of its high productivity and small variation. It is also a preferred embodiment to vibrate the carbon fibers with ultrasonic waves when applying the sizing agent.
• a carbon fiber bundle containing a sizing agent is obtained by applying a solution of a sizing agent and then drying the carbon fiber bundle by contact drying means as a drying step, for example, by contacting the carbon fiber bundle with a heated roller.
• contact drying means as a drying step, for example, by contacting the carbon fiber bundle with a heated roller.
• the carbon fiber bundle introduced into the heated roller is pressed against the heated roller by tension and dried rapidly, so that the flat shape of the carbon fiber bundle widened by the heated roller is easily fixed by the sizing agent. Since the flat carbon fiber bundle has a small contact area between the single fibers, the contact area with the gas increases when the sizing agent is thermally decomposed, and the decomposition efficiency tends to be high.
• heat treatment may be further added as a second drying step.
• a non-contact heating method that facilitates heat treatment at a high temperature is preferable.
• the drying temperature is preferably in the temperature range of 110-140°C.
• the temperature is 110° C. or higher, the moisture content of the sizing agent can be reduced, so that the thermal decomposability can be easily improved. 120° C. or higher is more preferable.
• the upper limit of the drying temperature to 140° C. or less, partial volatilization of the sizing agent can be suppressed, and handleability can be easily maintained. 135° C. or lower is more preferable.
• the heat treatment can also be performed by microwave irradiation and/or infrared irradiation.
• the mass of the sizing agent was determined by The sizing agent content (% by mass) was obtained by converting the mass of this sizing agent into mass% (rounded off to the third decimal place) with respect to 100% by mass of the carbon fiber bundle containing the sizing agent. The measurement was performed twice, and the average value was taken as the sizing agent content. When the carbon fiber does not contain a sizing agent, the value obtained in this measurement is the amount of thermal decomposition of the carbon fiber.
• the preferred range of the sizing agent content in the carbon fiber bundle after heat treatment at 250° C. for 20 seconds in an oxidizing atmosphere was evaluated in four stages according to the following criteria.
• D The sizing agent content is less than 0.02% by mass or more than 0.10% by mass.
• the surface oxygen concentration (O/C) of carbon fibers was measured by X-ray photoelectron spectroscopy according to the following procedure. First, after cutting the carbon fiber into 20 mm and arranging it on a copper sample support, using AlK ⁇ 1 , 2 as an X-ray source, the inside of the sample chamber was kept at 1 ⁇ 10 -8 Torr, and the photoelectron escape angle was set to 45° and X-ray photoelectron spectroscopy was performed. The binding energy value of the main peak of C 1S was adjusted to 285 eV as a correction value for the peak associated with electrification during measurement.
• the C 1S peak area was determined by drawing a linear baseline over the range of 275 to 290 eV as binding energy values.
• the O 1s peak area was determined by drawing a linear baseline over the range of 525 to 540 eV as binding energy.
• ESCA-1600 manufactured by ULVAC-Phi, Inc. was used as an X-ray photoelectron spectrometer.
• the photoelectron intensity ratio (b)/(a) on the surface of the carbon fiber was determined from the C 1S core spectrum obtained according to the above procedure, according to the following procedure.
• the linear baseline of 282 to 292 eV from which the C 1S peak area was obtained is defined as the origin of the photoelectron intensity, and the photoelectron intensity (a) detected at a binding energy of 284.6 eV (cps: photoelectron intensity per unit time),
• the photoelectron intensity (b) (cps) detected at a binding energy of 286.1 eV was determined, and (b)/(a) was calculated.
• the preferred range of equivalence with the original carbon fiber surface condition was evaluated in four stages according to the following criteria.
• D Photoelectron intensity ratio (b)/(a) is less than 0.2 or more than 0.8.
• the fiber-to-fiber friction coefficient was calculated from the following formula. The measurement was performed twice, and the average value was taken as the fiber-to-fiber friction coefficient.
• the measurement bobbins used were placed in the measurement atmosphere temperature and humidity conditions (measurement conditions: 23 ⁇ 3° C./60 ⁇ 5%) two hours or more before the measurement.
• ⁇ Method for measuring CF rubbed fluff> Four metal bars (material: stainless steel SUS304) having a diameter of 20 mm and a surface roughness Rmax (JIS B 0601 (1982)) of 0.3 ⁇ m are placed at intervals of 150 mm, and a total of 1 carbon fiber bundle is attached to the metal bar. They were arranged in the vertical direction so as to pass while contacting at an angle of 0.57 ⁇ (rad). Then, the carbon fiber bundle is stretched over the metal bar, the unwinding tension from the package is set to 500 g, the carbon fiber bundle is pulled by the drive roll at a speed of 6 m per minute, and passed through the metal bar.
• the fiber thread was irradiated with a laser beam perpendicularly from the side surface, and the number of fluffs was detected and counted for 1 minute by a fluff detector, and the number of fluffs was recorded.
• the preferable range of handleability was evaluated in three stages according to the following criteria, A and B were regarded as acceptable, and C was regarded as unacceptable.
• Materials and components used in each example and each comparative example are as follows.
• A Component: A-1: Triethylene glycol (molecular weight: 150, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.)
• A-3 Acetylene glycol-based surfactant (molecular weight: 290, Nissin Chemical Industry Co., Ltd.
• A-4 polyethylene glycol (molecular weight: 300, PEG300 manufactured by Sanyo Chemical Industries, Ltd.)
• A-5 Polypropylene glycol (molecular weight: 400, Newpol GP400 manufactured by Sanyo Chemical Industries, Ltd.)
• A-6 diethylene glycol (molecular weight: 106, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.)
• A-7 Polyethylene glycol (molecular weight: 600, PEG600 manufactured by Sanyo Chemical Industries, Ltd.)
• A-8 Polypropylene glycol (molecular weight: 600, PPG600 manufactured by Sanyo Chemical Industries, Ltd.)
• A-9 Acetylene glycol-based surfactant (molecular weight: 466, manufactured by Nissin Chemical Industry Co., Ltd., "Surfinol (registered trademark)” 465)
• A-10 Bisphenol A ethylene oxide adduct (molecular weight: 490, Newpol BPE60 manufactured by
• A-11 Glycerol polyglycidyl ether (molecular weight: 400, “Denacol (registered trademark)” Ex-313 manufactured by Nagase ChemteX Corporation)
• A-12 4-tert-butylphenyl glycidyl ether (Molecular weight: 206, manufactured by Tokyo Chemical Industry Co., Ltd.)
• A-13 Polyethyleneimine (Molecular weight: 800, “Lupasol (registered trademark)” FG manufactured by BASF Japan Ltd.).
• the reference example consists of the following two steps.
• the amount of thermal decomposition of the carbon fibers obtained in the first step, the surface oxygen concentration, the photoelectron intensity ratio on the surface of the carbon fiber bundles, and the fiber-to-fiber friction coefficient were measured.
• the thermal decomposition amount of the carbon fiber bundle was 0.05% by mass
• the surface oxygen concentration of the carbon fiber was 0.18
• the photoelectron intensity ratio on the surface of the carbon fiber bundle was 0.4
• the fiber-to-fiber friction coefficient was 0.4. became 42.
• Example 1 consists of the following first to fourth steps.
• Example 1 A step of producing carbon fiber as a raw material Spinning and baking acrylonitrile copolymer, total number of filaments 12,000, total fineness 800 tex, strand tensile strength 5.1 GPa, strand tensile modulus A carbon fiber of 240 GPa was obtained.
• the carbon fiber bundle was subjected to electrolytic surface treatment using an ammonium hydrogen carbonate aqueous solution as an electrolytic solution with an amount of electricity of 80 coulombs per 1 g of carbon fiber.
• the carbon fibers subjected to the electrolytic surface treatment were then washed with water and dried in heated air at 150° C. for the purpose of removing water, thereby obtaining carbon fibers as a raw material.
• the surface oxygen concentration of the carbon fiber obtained in the first step, the photoelectron intensity ratio on the surface of the carbon fiber bundle, and the fiber-to-fiber friction coefficient were measured.
• Step of Incorporating a Sizing Agent into Carbon Fibers As a sizing agent, (A-1) was made to have the composition shown in Table 2, and was dissolved by adding water to obtain an aqueous solution of about 1.5% by mass. This aqueous solution is used as a sizing agent solution, and after the sizing agent is added to the surface-treated carbon fiber bundle by an immersion method, heat treatment is performed at a temperature of 120 ° C. for 5 seconds with a hot roller as a drying step to add the sizing agent. A carbon fiber bundle was obtained. The content of the sizing agent was adjusted to 0.7% by mass in 100% by mass of the total carbon fiber bundle containing the surface-treated sizing agent. Further, when the thermal weight loss rate of the sizing agent was evaluated by the following method, the thermal weight loss rate A was 4.8%, the thermal weight loss rate B was 99.5%, and the thermal weight loss rate C was 99.8%. .
• Thermal weight loss rate A is calculated from the formula (A).
• Thermal weight loss rate A (%) ⁇ (W A0 ⁇ W A1 )/W A0 ⁇ 100 (A) ⁇ Thermal weight loss rate B> Weigh the sizing agent in the range of 10 ⁇ 2 mg (this weighed mass is W B0 (mg)), and use a thermogravimetry device to measure 200 ml (volume at 1 atm, 25 ° C.) / min of nitrogen The temperature of the sizing agent is increased from 30°C at a rate of 10°C/min in an air stream, and the mass of the sizing agent when reaching 250°C is measured (this measured mass is W B1 (mg)), and the following formula is obtained: The thermal weight loss rate B is calculated from (B).
• ⁇ Fourth step Evaluation of sizing agent content and carbon fiber surface state after heat treatment. A carbon fiber bundle containing a sizing agent was obtained after being burned off for a second.
• Example 2 A sizing agent is contained in the same manner as in Example 1, except that the sizing agent is mixed at a ratio of 90% by mass of (A-1) and 10% by mass of (A-11) in the second step.
• Various evaluations were performed by obtaining a carbon fiber bundle to be used. The results are shown in Table 2. It was found that the handleability was very good, the thermal decomposability of the sizing agent was very high, and the carbon fiber surface was sufficiently close to the original value shown in Reference Example 1. .
• Example 3 A sizing agent is contained in the same manner as in Example 1, except that the sizing agent is mixed at a ratio of 80% by mass of (A-1) and 20% by mass of (A-12) in the second step.
• Various evaluations were performed by obtaining a carbon fiber bundle to be used. The results are shown in Table 2. It was found that the handleability was very good, the thermal decomposability of the sizing agent was very high, and the carbon fiber surface was sufficiently close to the original value shown in Reference Example 1. .
• Example 4 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent was changed to (A-2) in the second step, and various evaluations were performed. The results are shown in Table 2. It was found that the handling property was very good, the thermal decomposability of the sizing agent was very high, and the carbon fiber surface was very close to the original value shown in Reference Example 1. .
• Example 5 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent was changed to (A-3) in the second step, and various evaluations were performed. The results are shown in Table 2. It was found that the handling property was very good, the thermal decomposability of the sizing agent was very high, and the carbon fiber surface was very close to the original value shown in Reference Example 1. .
• Example 6 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent was changed to (A-4) in the second step, and various evaluations were performed. The results are shown in Table 2. It was found that the handling property was very good, the thermal decomposability of the sizing agent was sufficiently high, and the carbon fiber surface was sufficiently close to the original value shown in Reference Example 1. .
• Example 7 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent was changed to (A-5) in the second step, and various evaluations were performed. The results are shown in Table 2. It was found that the handling property was very good, the thermal decomposability of the sizing agent was sufficiently high, and the carbon fiber surface was sufficiently close to the original value shown in Reference Example 1. .
• Example 8 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent content was changed to 0.4% by mass in the second step, and various evaluations were performed. The results are shown in Table 3. It was found that the handling property was very good, the thermal decomposability of the sizing agent was very high, and the carbon fiber surface was very close to the original value shown in Reference Example 1. .
• Example 9-11 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent and the sizing agent content before heat treatment were changed as shown in Table 2 in the second step, and various evaluations were performed. went. The results are shown in Table 3. It was found that the handleability was sufficiently good, the thermal decomposability of the sizing agent was very high, and the carbon fiber surface was very close to the original value shown in Reference Example 1. .
• Example 12 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent and the sizing agent content before heat treatment were changed as shown in Table 2 in the second step, and various evaluations were performed. went. The results are shown in Table 3. It was found that the handleability was sufficiently good, the thermal decomposability of the sizing agent was sufficiently high, and the carbon fiber surface was sufficiently close to the original value shown in Reference Example 1. .
• Example 14 Carbon fibers were obtained in the same manner as in Example 1, except that in the first step, the amount of electricity was changed to 10 coulombs per 1 g of carbon fiber and the electrolytic surface treatment was performed, and various evaluations were performed. The results are as shown in Table 3. The handleability was sufficiently good, the thermal decomposability of the sizing agent was extremely high, and the photoelectron intensity ratio (b)/(a) on the carbon fiber surface after heat treatment was low. However, it was found that the carbon fiber surface was very close to the original values shown in Reference Example 3.
• Example 15 Same as Example 1, except that in the second step, the sizing agent was mixed at a ratio of 90% by mass of (A-1) as the first component and 10% by mass of (A-10) as the second component.
• a carbon fiber bundle containing a sizing agent was obtained in the same manner and various evaluations were performed. The results are as shown in Table 3. It was found that the handleability was very good, the thermal decomposability of the sizing agent was sufficiently high, and the carbon fiber surface was sufficiently close to the original value shown in Reference Example 1. .
• Example 1 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent was changed to (A-6) in the second step, and various evaluations were performed. The results are as shown in Table 4. The thermal weight loss rate A volatilized greatly, and the sizing agent could not adhere to the carbon fibers, resulting in poor handleability.
• Example 2 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent was changed to (A-7) in the second step, and various evaluations were performed. The results are shown in Table 4, and the handleability was very good. It remained, and carbon fiber surface analysis was not possible.
• Example 3 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent was changed to (A-8) in the second step, and various evaluations were performed. The results are shown in Table 4. The handleability was very good, but the heat loss rate B was small and the thermal decomposition of the sizing agent was poor.
• Example 4 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent was changed to (A-9) in the second step, and various evaluations were performed. The results are shown in Table 4, and the handleability was very good. A large amount remained on the surface, and carbon fiber surface analysis could not be performed.
• Example 5 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent was changed to (A-10) in the second step, and various evaluations were performed. The results are shown in Table 4, and the handleability was very good. A large amount remained on the surface, and carbon fiber surface analysis could not be performed.
• Example 6 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent was changed to (A-11) in the second step, and various evaluations were performed. The results are shown in Table 4, and the handleability was very good. The sizing agent remained on the surface of the carbon fiber even after the heat treatment.
• Example 7 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent was changed to (A-13) in the second step, and various evaluations were performed. The results are shown in Table 4, and the handleability was very good. The sizing agent remained on the surface of the carbon fiber even after the heat treatment.
• Example 8 A carbon fiber bundle containing a sizing agent was obtained in the same manner as in Example 1, except that the sizing agent was changed to (A-7) in the second step and the heating temperature was changed to 400 ° C. in the fourth step. Then, various evaluations were performed. The results are shown in Table 4. The handleability was very good, and no sizing agent remained. Even the surface of the carbon fiber was decomposed.
• Example 9 A carbon fiber containing a sizing agent in the same manner as in Example 1, except that (A-1) was mixed at a ratio of 30% by mass and (A-11) at a ratio of 70% by mass in the second step. A bundle was obtained and various evaluations were performed. The results are shown in Table 4, and the handleability was very good. However, the sizing agent had poor thermal decomposability due to the small thermal weight loss rate C, and the sizing agent remained on the carbon fiber surface even after the heat treatment. .
• Example 10 A carbon fiber containing a sizing agent in the same manner as in Example 1, except that (A-1) was mixed at a ratio of 30% by mass and (A-12) at a ratio of 70% by mass in the second step. A bundle was obtained and various evaluations were performed. The results are shown in Table 4. The handling property was very good, but no sizing agent remained. The photoelectron intensity ratio (b)/(a) on the carbon fiber surface was high, and the sizing agent remained on the carbon fiber surface even after the heat treatment.
• the sizing agent on the carbon fiber bundle is thermally decomposable at a low temperature that suppresses the thermal decomposition of the oxygen-containing functional groups on the surface of the carbon fiber.
• the thermoplastic resin composite using the present invention is lightweight and has excellent strength, so it is suitably used in many fields such as aircraft members, spacecraft members, automobile members, ship members, civil engineering and construction materials, and sporting goods. be able to.

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