WO2023167120A1 - Carbon fiber bundle and method for producing carbon fiber bundle - Google Patents

Carbon fiber bundle and method for producing carbon fiber bundle Download PDF

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Publication number
WO2023167120A1
WO2023167120A1 PCT/JP2023/006919 JP2023006919W WO2023167120A1 WO 2023167120 A1 WO2023167120 A1 WO 2023167120A1 JP 2023006919 W JP2023006919 W JP 2023006919W WO 2023167120 A1 WO2023167120 A1 WO 2023167120A1
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Prior art keywords
carbon fiber
fiber bundle
gpa
strength
absorbance
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PCT/JP2023/006919
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French (fr)
Japanese (ja)
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堀之内綾信
松浦友樹
奥田治己
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東レ株式会社
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Publication of WO2023167120A1 publication Critical patent/WO2023167120A1/en

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    • 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
    • D06M10/00—Physical treatment of fibres, threads, yarns, fabrics, or fibrous goods made from such materials, e.g. ultrasonic, corona discharge, irradiation, electric currents, or magnetic fields; Physical treatment combined with treatment with chemical compounds or elements

Definitions

  • the present invention relates to carbon fiber bundles that are suitably used for sports applications such as golf shafts and fishing rods, as well as for aircraft members, automobile members, and ship members, and other general industrial applications.
  • the present invention relates to a carbon fiber bundle which has excellent adhesive strength with a matrix resin and is less prone to sticking between single filaments after application of a sizing agent, and a method for producing the same.
  • carbon fiber has high specific strength and specific modulus, it is widely used as a reinforcing fiber for composite materials in fields such as sports applications, aerospace applications, automobiles, civil engineering and construction, pressure vessels, and wind turbine blades.
  • One of the points for reflecting the excellent properties of carbon fibers in carbon fiber reinforced composite materials is to increase the adhesive strength between the carbon fibers and the matrix resin. Therefore, it is common practice to form functional groups on the surface of carbon fibers by various oxidation methods, or to provide sizing agents.
  • Electrolytic oxidation treatment is widely used industrially as a method of oxidizing the surface of carbon fibers. By oxidizing the surface of the carbon fiber, the adhesion to the matrix resin can be increased, but depending on the conditions, excessively oxidized portions (sometimes called weak portions) are formed on the surface of the carbon fiber. It is known.
  • Patent Document 1 proposes a method of performing electrolytic oxidation treatment in an alkaline aqueous solution or air oxidation treatment in order to suppress the formation of such fragile portions.
  • Patent Document 2 proposes a method of performing electrolytic oxidation treatment in an alkaline aqueous solution and then washing with warm water.
  • Patent Document 3 proposes a method of suppressing the formation of fragile portions by performing electrolytic oxidation treatment in an acidic aqueous solution after performing an electrolytic oxidation treatment in an alkaline aqueous solution.
  • Patent Document 4 describes a method of heating a carbon fiber bundle at 470 to 650°C in the air to oxidize the surface of the carbon fiber bundle.
  • Patent Document 5 describes a method for improving shear strength with a matrix resin by treating carbon fiber bundles in air at 378 to 600° C. for at least 30 minutes.
  • Patent Document 6 proposes a method of increasing the adhesiveness to a matrix resin by heating a carbon fiber bundle in an oxygen-containing atmosphere and then subjecting it to an electrolytic oxidation treatment.
  • Patent Document 1 mentions the air oxidation treatment, there is no description or suggestion of detailed conditions, and the adhesion to the matrix resin cannot necessarily be effectively enhanced.
  • Patent Document 2 the effect of removing fragile portions by washing with warm water is not always sufficient, and sticking cannot always be suppressed when a specific sizing agent is applied.
  • Patent Document 3 does not necessarily have a sufficient effect of suppressing sticking.
  • Patent Literature 4 although it is thought that the formation of fragile portions can be suppressed by performing the air oxidation treatment, the effect of improving the adhesive force was insufficient.
  • Patent Document 5 requires a long time of treatment, which has the problem of lowering the tensile strength of the carbon fiber.
  • Patent Document 6 high adhesion cannot be found by air oxidation treatment alone, and electrolytic treatment is performed after air oxidation treatment, resulting in a problem of a multi-stage process.
  • the problem to be solved by the present invention is to provide a high-performance carbon fiber that does not reduce the tensile strength of the carbon fiber, has excellent adhesive strength, and does not cause sticking between single fibers even when a specific sizing agent is applied.
  • An object of the present invention is to provide a carbon fiber bundle suitable for obtaining a fiber-reinforced composite material and a method for producing the same.
  • the present invention has the following configurations. i.e. [1] A carbon fiber bundle satisfying the following (1) or (2).
  • Absorbance at a wavelength of 260 nm is 0.005 or more
  • the absorbance ratio (I 550 nm /I 800 nm ) which is the ratio of the absorbance at a wavelength of 550 nm to the absorbance at a wavelength of 800 nm, is 1.8 or less
  • the loop strength ⁇ L (GPa) and the strand strength A carbon fiber bundle having a ratio ( ⁇ L / ⁇ S ) to ⁇ S (GPa) of 1.7 or more and an adhesive strength to LM-PAEK resin evaluated by a single fiber pull-out method of 68 MPa or more.
  • Absorbance at a wavelength of 260 nm is 0.005 or more
  • the absorbance ratio (I 550 nm /I 800 nm ) which is the ratio of the absorbance at a wavelength of 550 nm to the absorbance at a wavelength of 800 nm, is 1.8 or less
  • the loop strength ⁇ L (GPa) and the strand strength A carbon fiber bundle having a ratio ( ⁇ L / ⁇ S ) to ⁇ S (GPa) of 1.7 or more and an adhesive strength to LM-PAEK resin of 68 MPa or more as evaluated by a single fiber pull-out method.
  • the present invention it is possible to obtain a high-performance composite material that does not reduce the tensile strength of the carbon fiber bundle, has excellent adhesive strength, and is less likely to stick between single fibers even when a specific sizing agent is applied. It is possible to provide a carbon fiber bundle suitable for and a method for producing the same.
  • the carbon fiber bundle of the present invention is a carbon fiber bundle that satisfies (1) or (2) below, or a carbon fiber bundle that satisfies at least one or more of (1) to (3) below.
  • Absorbance at a wavelength of 260 nm is 0.005 or more
  • the absorbance ratio (I 550 nm /I 800 nm ) which is the ratio of the absorbance at a wavelength of 550 nm to the absorbance at a wavelength of 800 nm, is 1.8 or less
  • the loop strength ⁇ L (GPa) and the strand strength ⁇ A carbon fiber bundle having a ratio ( ⁇ L / ⁇ S ) to S (GPa) of 1.7 or more and an adhesive strength to LM-PAEK resin evaluated by a single fiber pull-out method of 68 MPa or more.
  • dimethyl sulfoxide As the solvent for the extract will be explained.
  • the weak portion formed on the surface of the carbon fiber bundle has a polar functional group such as an oxygen functional group
  • the basic skeleton is composed of hydrophobic carbon, so it is not sufficiently extracted with water or the like.
  • dimethyl sulfoxide is highly effective in extracting weak portions formed on the surface of carbon fiber bundles.
  • dimethyl sulfoxide has polarity due to the sulfone group, and has a non-polar part due to the methyl group, and has an affinity with the weak part formed on the surface of the carbon fiber bundle. It can be interpreted as good.
  • I 260 nm corresponds to the amount of brittle portions that are related to the adhesive strength to some extent among the brittle portions generated by surface treatment of the carbon fiber bundle, and the larger I 260 nm is, the more easily the adhesive strength increases. Therefore, I260nm must be 0.005 or more.
  • I 550 nm /I 800 nm in (1) above is preferably 1.5 or less, more preferably 1.3 or less. Also, I 550 nm is preferably 0.02 or less, more preferably 0.005 or less. In (1) above, I800nm is preferably 0.01 or less, more preferably 0.005 or less. In order to make I550nm / I800nm equal to or less than 1.8 in (1) above, it can be achieved, for example, by adopting the surface treatment conditions described later.
  • I 550 nm is 0.015 or less.
  • I 800nm which is the denominator of I 550nm /I 800nm , may take a very small value or a negative value depending on how the baseline is taken.
  • I 800 nm may deviate from the range specified in (1) above, it was found that even in such cases, if I 550 nm is within the above range, a high anti-sticking effect is exhibited.
  • I550nm is preferably 0.01 or less, more preferably 0.005 or less. In order to make I 550 nm equal to or less than 0.015 in (2) and (3) above, for example, it can be achieved by adopting the surface treatment conditions described later.
  • the carbon fiber bundles in (1) and (2) above have a ratio ( ⁇ L / ⁇ S ) of loop strength ⁇ L (GPa) to strand strength ⁇ S (GPa) of 1.7 or more.
  • the larger the ratio the higher the loop strength, which will be described later, relative to the strand strength.
  • the tensile strength of carbon fiber changes according to the length to be measured, and the shorter the length, the lower the expected value of the product of the length and the probability of existence of defects per length, that is, the number of defects. , the tensile strength is higher.
  • Loop strength is a method that can selectively apply tensile stress to an extremely short length range by bending carbon fibers into a loop. means strength.
  • the loop strength ⁇ L (GPa) of the carbon fiber bundle in (3) above is 8.0 GPa or more. If ⁇ L is 8.0 GPa or more, the tensile strength of the unidirectionally reinforced composite material tends to be high even if there is some variation in strand strength ⁇ s.
  • the carbon fiber bundle of the present invention has an adhesive strength of 68 MPa or more with LM-PAEK resin evaluated by the pull-out method.
  • the LM-PAEK resin means a low-melting polyaryletherketone resin, and in the present invention, "Victrex" (registered trademark) AE250 manufactured by Victrex.
  • Adhesive strength to LM-PAEK resin is preferably 70 MPa or more, more preferably 75 MPa or more.
  • the strength in the non-fiber axial direction of the carbon fiber reinforced composite material is particularly improved as the adhesive strength increases. There was a problem that the tensile strength of In order to avoid such a problem and increase the adhesive strength to LM-PAEK resin to 68 MPa or more, it can be achieved by, for example, adopting the surface treatment conditions described later.
  • the carbon fiber bundle in the present invention preferably has a mass reduction rate of 50% or less when heated in air at 550° C. for 3 hours.
  • the carbon fiber bundle in the present invention is a carbon fiber bundle obtained by using a carbon fiber bundle obtained by a known method as a raw material (hereinafter referred to as a raw material carbon fiber bundle), for example, by performing a specific surface treatment.
  • a raw material carbon fiber bundle obtained by a known method as a raw material
  • the mass reduction rate of the carbon fiber bundle is more preferably 30% or less, more preferably 25% or less.
  • the metal content refers to the total amount of sodium, potassium, calcium, iron, zinc and copper.
  • the metal content contained in the carbon fiber bundle can be measured by atomic absorption spectrometry for sodium and potassium, and by ICP emission spectrometry for other metal elements.
  • the surfaces of reaction vessels, stirring devices, and piping in polymerization equipment are coated with glass or Teflon, and stainless steel is used. It is preferable to form a protective layer that prevents metal elements from eluting into the PAN-based polymer solution by maintaining a good passivation layer on the surface of the steel and a good surface finish. It is also an effective means to use water having a metal content as low as possible in the carbon fiber bundle manufacturing process.
  • the method for producing a carbon fiber bundle of the present invention is characterized by processing at 700°C or higher for 0.1 to 6 seconds in an oxygen-containing atmosphere. That is, for example, the carbon fiber bundle of the present invention can be obtained by treating a raw material carbon fiber bundle in an oxygen-containing atmosphere at 700° C. or higher for 0.1 to 6 seconds.
  • raw carbon fiber bundles include PAN-based, rayon-based, and pitch-based raw carbon fiber bundles.
  • PAN-based carbon fiber bundles are preferably used as a raw material because they have an excellent balance between strength and elastic modulus.
  • the raw material PAN-based carbon fiber bundle may be obtained by a known method. As a step of surface-treating the raw material carbon fiber bundle, the raw material carbon fiber bundle is heated at 700° C.
  • a heating furnace having an entrance through which the raw material carbon fiber bundle can be introduced is used, and the raw material carbon fiber bundle is passed through the heating furnace.
  • Such treatment time may be adjusted by changing the furnace length of the heating furnace, or by changing the speed of the carbon fiber bundles to be passed.
  • the heat treatment may be performed in multiple stages by installing a plurality of heating furnaces.
  • the oxygen-containing atmosphere in the present invention is an atmosphere containing air and/or oxygen or a mixed gas of a plurality of kinds, and the oxygen concentration in the furnace may be controlled by mixing an inert gas such as argon or nitrogen.
  • an inert gas such as argon or nitrogen.
  • the heating temperature is 470° C. to 650° C., and it can be seen that this temperature range is conventionally considered important. In this temperature range , although sufficient adhesive strength is not exhibited, it is true that ⁇ L (GPa) is less likely to decrease. Therefore, it is assumed from the known literature that ⁇ L (GPa) decreases when the temperature of the heat treatment is further increased beyond this temperature range.
  • ⁇ L GPa
  • the heating temperature is preferably 800 to 1,400 ° C., more preferably 800 to 1,200 ° C.
  • 900 to 1,000°C is more preferable.
  • the heat treatment time is preferably changed appropriately according to the heat treatment temperature, but from the viewpoint of improving productivity, the shorter the better, preferably 0.1 to 3 seconds, more preferably 0.1 to 2 seconds.
  • the carbon fiber bundle in the present invention preferably has a fineness of 0.4 to 3.0 g/m and a filament number of preferably 1,000 to 100,000, more preferably 3,000 to 50,000.
  • the strand strength is preferably 1 to 10 GPa, more preferably 3 to 10 GPa.
  • the strand elastic modulus is preferably 200 to 1,000 GPa, more preferably 200 to 500 GPa.
  • a glass screw bottle containing carbon fiber bundles and dimethyl sulfoxide is introduced into an ultrasonic irradiation device (Bransonic (registered trademark) CPX5800-J), and ultrasonic waves are applied for 10 minutes under the conditions of an oscillation frequency of 40 kHz, a high frequency output of 160 W, and 25 ° C. processed.
  • the supernatant liquid in the glass screw bottle was used as an extract sample, and the absorbance at a wavelength of 260 nm (I 260 nm ) and the absorbance at a wavelength of 550 nm were measured using a UV-visible spectrophotometer (JASCO, V-550).
  • the number of measurements in the tensile test was 6, and the average value of each measurement result was taken as the strand elastic modulus E and strand strength ⁇ S (GPa) of the carbon fiber bundle.
  • "BAKELITE” registered trademark
  • 2021P manufactured by Daicel Corporation
  • the loop strength ⁇ L (GPa) was evaluated by the following method. That is, a monofilament having a length of about 10 cm is placed on a slide glass, 1-2 drops of water are dropped on the central portion, and both ends of the monofilament are lightly twisted in the fiber circumferential direction to form a loop in the central portion of the monofilament. A cover glass was placed over it. This was installed on the stage of a microscope, and moving images were taken under conditions of a total magnification of 100 times and a frame rate of 15 frames/second.
  • strain was applied until the single fiber broke by pressing both ends of the looped fiber toward the glass slide and pulling it in the opposite direction at a constant speed. .
  • a frame immediately before the breakage was identified by frame advance, and the width W ( ⁇ m) of the loop immediately before the breakage was measured by image analysis.
  • d/W was calculated by dividing the fiber diameter d ( ⁇ m) by the width W of the loop immediately before breaking.
  • the test was performed 20 times, the average value of d/W was obtained, and the value was multiplied by the strand elastic modulus E, that is, the value obtained by E ⁇ d/W was defined as the loop strength ⁇ L (GPa). Also, the ratio ( ⁇ L / ⁇ S ) between the loop strength ⁇ L (GPa) and the strand strength ⁇ S (GPa) was obtained.
  • the fiber diameter d was measured according to JIS R 7607 (2000). Specifically, the mass A f (g/m) per unit length and the specific gravity B f ( ⁇ ) were determined for the carbon fiber bundle composed of a large number of carbon filaments to be measured. The fiber diameter d ( ⁇ m) of the carbon fiber bundle was calculated by the following formula 1 from the obtained values of A f and B f and the number of filaments C f of the carbon fiber bundle to be measured.
  • Adhesive strength evaluation with LM-PAEK resin is measured by a single fiber pull-out method.
  • an interface evaluation device (3093-1000) manufactured by Kotobuki Engineering Co., Ltd. was used.
  • LM-PAEK resin (“Victrex” (registered trademark) AE250 manufactured by Victrex) was made into a plate by hot pressing and cut to obtain LM-PAEK resin used for measurement. The cut plate-shaped LM-PAEK resin was placed on a heating stage and heated to a temperature of 370° C. to melt it.
  • a single yarn taken out from the carbon fiber bundle is embedded in the melted LM-PAEK resin with a micrometer aiming at an embedding depth of about 40 ⁇ m, and cooled to room temperature.
  • a sample was prepared in which the monofilament was embedded in PAEK resin. The embedded sample was set in a load cell, and the maximum load (g) and the actual embedding depth ( ⁇ m) when the single yarn was pulled out from the LM-PAEK resin were measured.
  • the drawing speed during drawing was set to 1.0 ⁇ m/s.
  • the actual depth of burying was obtained from the distance from the point at which the load started to be applied at the beginning of pulling out to the point at which the load was removed after the thread was pulled out of the resin.
  • the adhesive strength (MPa) was calculated from the obtained maximum load and actual embedding depth ( ⁇ m) based on Equation 2 below.
  • the fiber diameter d ( ⁇ m) is the value obtained based on the above formula 1.
  • ⁇ Mass reduction rate when heated in air for 3 hours > About 3 g of a carbon fiber bundle was placed in a ceramic crucible, introduced into an electric furnace preheated to 550° C., and heat-treated for 3 hours. After heat treatment for 3 hours, the ceramic crucible containing the carbon fiber bundle was taken out from the electric furnace, and the mass of the carbon fiber bundle was measured. The mass reduction rate (%) when heated in air for 3 hours was calculated by the following formula 3.
  • ⁇ Metal content> About 0.7 g of the carbon fiber bundle was subjected to low-temperature ashing treatment in a plasma reactor, and the obtained sample was dissolved in dilute nitric acid to obtain a measurement sample.
  • the amount of sodium and potassium was measured by atomic absorption spectrometry, other metal elements were measured by ICP emission spectrometry, and the total amount of sodium, potassium, calcium, iron, zinc, aluminum, and magnesium was determined as metal content.
  • aqueous solution of about 0.6% by mass was obtained by dissolving polyethyleneimine (“Lupasol” (registered trademark) G20 Water-free, manufactured by BASF Japan Ltd.) in water.
  • the sizing agent is applied to the surface-treated carbon fiber bundle by an immersion method, and then heat treated with a hot roller at a temperature of 120 ° C. for 30 seconds as a preliminary drying step.
  • heat treatment was performed in heated air at a temperature of 220° C. for 135 seconds to obtain a sizing agent-coated carbon fiber bundle.
  • the amount of the sizing agent applied was adjusted to 0.30 parts by mass with respect to 100 parts by mass of the total surface-treated carbon fiber bundle coated with the sizing agent. After that, the number of fixation was evaluated by the method described below.
  • Sodium dioctyl sulfosuccinate manufactured by Tokyo Kasei Kogyo Co., Ltd.
  • anionic surfactant was dissolved in 100 g of water to a concentration of 0.05% by mass to prepare a dispersion medium.
  • a carbon fiber bundle to be measured cut to a length of 5 mm was put into the dispersion medium which had been stirred by a magnetic stirrer rotating at 200 rpm. After stirring for 30 seconds, suction filtration was performed, and the filter paper after filtration was allowed to stand for 2 hours in a place not exposed to wind and air-dried.
  • the filter paper was sandwiched between laminated films and passed through a laminator for lamination. The entire surface of the laminated filter paper was photographed with an optical microscope.
  • a lump having a thickness of 40 ⁇ m or more that looks like a single thick fiber because a plurality of single yarns are gathered in parallel and in contact with each other without gaps. was defined as sticking.
  • Image processing was performed using the open source software imageJ as follows. First, load the image to be analyzed into imageJ, draw a line segment that passes through the position that bisects the long axis of the single yarn mass whose diameter you want to measure and is perpendicular to the long axis, and select "Plot profile" of the "Analyze” command. By selecting , the intensity profile along the line segment was obtained. The half-value width of the profile was read, and the actual size was converted into the "thickness" of the bundle of single yarns.
  • Tables 1 and 2 show the results of Examples and Comparative Examples.
  • Example 1 Polymerization of the polymer for the carbon fiber precursor was carried out in dimethyl sulfoxide containing no metal element, and a raw material carbon fiber bundle with a metal content of 30 ppm (number of filaments: 12,000, strand strength: 4.9 GPa, elastic modulus: 230 GPa , fiber diameter 6.9 ⁇ m) was subjected to oxidation treatment at 750° C. for 6 seconds in an air atmosphere.
  • ⁇ L / ⁇ S was 2.3, which was almost the same as Comparative Example 1 without surface treatment.
  • the mass reduction rate when heated in air at 550 ° C.
  • Example 6 for 3 hours is 19%, which is smaller than that of Example 6 with a high metal content, and ⁇ L and ⁇ L / ⁇ S are higher than those of Example 6. was also expensive.
  • the adhesive strength with LM-PAEK resin was 71 MPa. Compared to Comparative Examples 2 and 3 with low heating temperatures, the adhesion to LM-PAEK resin was high. The number of fixation after application of the sizing agent was 3, which was significantly less than in Comparative Examples 5 and 6.
  • Example 2 The oxidation treatment was performed in the same manner as in Example 1 except that the heating temperature was changed to 1,200° C. and the treatment time was set to 0.1 second.
  • the adhesive strength with LM-PAEK resin was 73 MPa. Compared to Comparative Examples 2 and 3 with low heating temperatures, the adhesion to LM-PAEK resin was high.
  • Example 3 The oxidation treatment was performed in the same manner as in Example 1, except that the heating temperature was changed to 800° C. and the treatment time was set to 3 seconds.
  • I 550 nm /I 800 nm was 1.3, which was small compared to Comparative Examples 5 and 6.
  • the number of fixation after application of the sizing agent was 2, which was significantly less than in Comparative Examples 5 and 6.
  • ⁇ L was 11.0 GPa and ⁇ L / ⁇ S was 2.2, which were higher than Comparative Example 4 in which the treatment time was long.
  • Example 4 The oxidation treatment was performed in the same manner as in Example 1 except that the heating temperature was changed to 950° C. and the treatment time was set to 0.7 seconds. An adhesive strength of 75 MPa was exhibited with the LM-PAEK resin. Adhesion to LM-PAEK resin was improved more than in Example 1.
  • Example 5 The oxidation treatment was performed in the same manner as in Example 4, except that the heating temperature was changed to 1,000°C.
  • the adhesive strength with LM-PAEK resin was 79 MPa. Adhesion to LM-PAEK resin was improved more than in Example 4.
  • Example 6 Polymerization of the polymer for the carbon fiber precursor was carried out in a sodium thiocyanate aqueous solution containing a metal element, and the same method as in Example 1 was used except that a raw material carbon fiber bundle with a metal content of 1,000 ppm was used. oxidation treatment. The mass reduction rate when heated in air at 550° C. for 3 hours was 55%, which is larger than Example 1 with a small metal content . 9 and Example 1 were smaller.
  • Example 7 The oxidation treatment was performed in the same manner as in Example 1 except that the heating temperature was changed to 1,000° C. and the treatment time was set to 1.3 seconds.
  • the adhesive strength with LM-PAEK resin was 79 MPa.
  • I 550 nm was 0.002, and I 800 nm was 0.001, which is extremely small. Since I 800 nm is extremely small, I 550 nm /I 800 nm shows a high value of 2.0. was significantly less.
  • Example 8 The oxidation treatment was performed in the same manner as in Example 1 except that the heating temperature was changed to 1,100° C. and the treatment time was set to 0.7 seconds.
  • the adhesive strength with LM-PAEK resin was 78 MPa.
  • I 550 nm was 0.003, and I 800 nm was 0.001, which is extremely small. Since I 800 nm is extremely small, I 550 nm /I 800 nm shows a high value of 3.0. was significantly less.
  • Example 9 The oxidation treatment was performed in the same manner as in Example 1 except that the heating temperature was changed to 900° C. and the treatment time was set to 2.6 seconds.
  • the adhesive strength with LM-PAEK resin was 77 MPa.
  • I 550 nm was 0.004, and I 800 nm was 0.001, which is extremely small. Since I 800 nm is extremely small, I 550 nm /I 800 nm shows a high value of 4.0. was significantly less.
  • Example 10 A raw material carbon fiber bundle (number of filaments: 24,000, strand strength: 6.3 GPa, elastic modulus: 294 GPa, fiber diameter: 5.4 ⁇ m) was subjected to oxidation treatment at 1,100° C.
  • ⁇ L was 10.2 GPa and ⁇ L / ⁇ S was 1.6.
  • Adhesive strength with LM-PAEK resin was 78 MPa, and the number of fixation was 2.
  • a raw material carbon fiber bundle (number of filaments: 12,000, strand strength: 4.0 GPa, elastic modulus: 230 GPa, fiber diameter: 6.9 ⁇ m) was subjected to oxidation treatment at 1,000° C. for 6 seconds in an air atmosphere.
  • ⁇ L was 7.6 GPa and ⁇ L / ⁇ S was 1.9.
  • the adhesive strength with the LM-PAEK resin was 78 MPa, and the number of fixation was 3.
  • Example 1 A carbon fiber bundle similar to that of Example 1 was used except that the surface oxidation treatment was not performed. The number of fixation due to application of the sizing agent was 0, and the adhesive strength with the LM-PAEK resin was 51 MPa. I 260 nm was as low as 0.002, and it is considered that the adhesive force with the LM-PAEK resin was low.
  • Example 2 The oxidation treatment was performed in the same manner as in Example 1 except that the heating temperature was 550° C. and the treatment time was 60 seconds.
  • the adhesive strength with LM-PAEK resin was 66 MPa, which was lower than that of Example 1.
  • Example 3 The oxidation treatment was performed in the same manner as in Example 1, except that the heating temperature was 600° C. and the treatment time was 6 seconds.
  • the adhesive strength with the LM-PAEK resin was 61 MPa, which was lower than that of Example 1 in which the heating temperature was high.
  • Example 4 The oxidation treatment was performed in the same manner as in Example 3, except that the treatment time was 30 seconds. ⁇ L and ⁇ L / ⁇ S were lower than Example 3 with a shorter treatment time.
  • Comparative Example 6 The treatment was carried out in the same manner as in Comparative Example 5 except that the amount of electrolytic treatment was changed to 30 C/g. I 550 nm /I 800 nm was 2.9, which is higher than that of Example 3, and the number of fixations after application of the sizing agent was as high as 94.
  • the carbon fiber bundles provided by the present invention are suitably used for sports applications such as golf shafts and fishing rods, as well as aircraft members, automobile members and ship members, and other general industrial applications.

Abstract

The purpose of the invention of the present application is to provide a carbon fiber bundle and a method for producing same, wherein the tensile strength of the carbon fiber bundle decreases less easily, and the carbon fiber bundle is excellent in adhesive force and less prone to fixation between single fibers even when a certain sizing agent is applied, and is suitable for obtaining a highly functional composite material.　The present invention is a carbon fiber bundle satisfying at least one or more of items (1) to (3) below. (1) Absorbance (I260 nm is 0.005 or more, the absorbance ratio (I550 nm/I800 nm) is 1.8 or less, the ratio (σL/σS) between loop strength σL and strand strength σS is 1.7 or more, and adhesive force with LM-PAEK resin evaluated by a single-fiber pull-out method is 68 MPa or more. (2) Absorbance (I550 nm) is 0.015 or less, the ratio (σL/σS) is 1.7 or more, and the adhesive force described above is 68 MPa or more. (3) Absorbance (I550 nm) is 0.015 or less, loop strength σL (GPa) is 8.0 GPa or more, and the adhesive force described above is 68 MPa or more.

Description

炭素繊維束および炭素繊維束の製造方法Carbon fiber bundle and method for producing carbon fiber bundle
　本発明は、航空機部材、自動車部材および船舶部材をはじめとして、ゴルフシャフトや釣竿等のスポーツ用途およびその他一般産業用途に好適に用いられる炭素繊維束に関するものであり、炭素繊維の引張強度を低下させることなく、マトリクス樹脂との接着力に優れ、且つ、サイジング剤付与後の単糸間固着が生じにくい炭素繊維束およびその製造方法に関するものである。 TECHNICAL FIELD The present invention relates to carbon fiber bundles that are suitably used for sports applications such as golf shafts and fishing rods, as well as for aircraft members, automobile members, and ship members, and other general industrial applications. The present invention relates to a carbon fiber bundle which has excellent adhesive strength with a matrix resin and is less prone to sticking between single filaments after application of a sizing agent, and a method for producing the same.
　炭素繊維は、高い比強度および比弾性率を有するため、複合材料用補強繊維として、スポーツ用途や航空・宇宙用途、自動車、土木・建築、圧力容器および風車ブレードなどの分野で幅広く展開されている。炭素繊維の優れた特性を炭素繊維強化複合材料に反映させるためのポイントの一つは、炭素繊維とマトリクス樹脂との接着力を高めることである。そこで、炭素繊維には、各種の酸化手法により繊維表面に官能基を形成させることや、サイジング剤を付与することが一般的に行われている。 Because carbon fiber has high specific strength and specific modulus, it is widely used as a reinforcing fiber for composite materials in fields such as sports applications, aerospace applications, automobiles, civil engineering and construction, pressure vessels, and wind turbine blades. . One of the points for reflecting the excellent properties of carbon fibers in carbon fiber reinforced composite materials is to increase the adhesive strength between the carbon fibers and the matrix resin. Therefore, it is common practice to form functional groups on the surface of carbon fibers by various oxidation methods, or to provide sizing agents.
　炭素繊維の表面の酸化手法としては、電解酸化処理が工業的に広く用いられている。炭素繊維の表面を酸化することにより、マトリクス樹脂との接着力を高めることができるが、条件によっては炭素繊維の表面に過剰に酸化した部分（脆弱部などと呼ばれることがある）が形成されることが知られている。特許文献１では、かかる脆弱部の形成を抑制するために、アルカリ性水溶液中で電解酸化処理を行うか、空気酸化処理を行う方法が提案されている。特許文献２では、アルカリ性水溶液中で電解酸化処理を行った後に温水で洗浄する方法が提案されている。特許文献３では、アルカリ性水溶液中で電解酸化処理を行った後に、さらに酸性水溶液中で電解酸化処理を行うことにより脆弱部の形成を抑制する方法が提案されている。 Electrolytic oxidation treatment is widely used industrially as a method of oxidizing the surface of carbon fibers. By oxidizing the surface of the carbon fiber, the adhesion to the matrix resin can be increased, but depending on the conditions, excessively oxidized portions (sometimes called weak portions) are formed on the surface of the carbon fiber. It is known. Patent Document 1 proposes a method of performing electrolytic oxidation treatment in an alkaline aqueous solution or air oxidation treatment in order to suppress the formation of such fragile portions. Patent Document 2 proposes a method of performing electrolytic oxidation treatment in an alkaline aqueous solution and then washing with warm water. Patent Document 3 proposes a method of suppressing the formation of fragile portions by performing electrolytic oxidation treatment in an acidic aqueous solution after performing an electrolytic oxidation treatment in an alkaline aqueous solution.
　また、電解酸化処理とは別の方法として、例えば、特許文献４では炭素繊維束を空気中にて４７０～６５０℃で加熱して炭素繊維束表面を酸化させる方法が記載されている。また特許文献５では炭素繊維束を空気中にて３７８～６００℃で最低３０分間処理することにより、マトリクス樹脂との剪断強度を向上させる方法が記載されている。さらに、特許文献６では炭素繊維束を酸素含有雰囲気中で加熱したあと電解酸化処理を行うことにより、マトリクス樹脂との接着性を高める方法が提案されている。 In addition, as a method other than the electrolytic oxidation treatment, for example, Patent Document 4 describes a method of heating a carbon fiber bundle at 470 to 650°C in the air to oxidize the surface of the carbon fiber bundle. Further, Patent Document 5 describes a method for improving shear strength with a matrix resin by treating carbon fiber bundles in air at 378 to 600° C. for at least 30 minutes. Furthermore, Patent Document 6 proposes a method of increasing the adhesiveness to a matrix resin by heating a carbon fiber bundle in an oxygen-containing atmosphere and then subjecting it to an electrolytic oxidation treatment.
特開昭６３－１９００２５公報JP-A-63-190025 特開２００４－２３８７６１号公報JP-A-2004-238761 特許第６０６０６７５号公報Japanese Patent No. 6060675 特開昭５５－６５１２号公報JP-A-55-6512 特公昭４５－１２８７号公報Japanese Patent Publication No. 45-1287 特開平３－２８７８６０号公報JP-A-3-287860
　しかしながら、背景技術の方法によれば、脆弱部の形成を確かに一定程度抑制はできるものの、マトリクス樹脂との接着力をさらに高める目的で特定のサイジング剤を付与した場合、わずかな脆弱部の存在によって炭素繊維の単糸間でサイジング剤が架橋反応してしまい、結果として炭素繊維の単糸間を固着させてしまうことがあり、マトリクス樹脂との接着力の向上と、複合材料としたときの欠点となる可能性のある固着の抑制を両立することが難しかった。 However, according to the method of the background art, although it is possible to suppress the formation of weak portions to a certain extent, when a specific sizing agent is applied for the purpose of further increasing the adhesive strength with the matrix resin, a slight weak portion is present. As a result, the sizing agent cross-links between the carbon fiber single yarns, and as a result, the carbon fiber single yarns may be fixed. It was difficult to achieve both suppression of sticking, which could be a drawback.
　特許文献１では、空気酸化処理について言及しているものの、詳細な条件に関する記載も示唆もなく、マトリクス樹脂との接着力を必ずしも効果的に高められるものではなかった。特許文献２は、温水洗浄による脆弱部の除去効果は必ずしも十分ではなく、特定のサイジング剤を付与したときに固着を必ずしも抑制できるものではなかった。特許文献３も、特許文献２と同じように、固着の抑制効果が必ずしも十分ではなかった。特許文献４は、空気酸化処理を行うことで脆弱部の形成は抑制できていると考えられるものの、接着力の向上効果が不足していた。また、特許文献５は長時間の処理が必要であり、それにより炭素繊維の引張強度が低下する課題があった。特許文献６では、空気酸化処理だけでは高接着を見出せず、空気酸化後に電解処理を行っており、多段プロセスとなってしまう課題があった。 Although Patent Document 1 mentions the air oxidation treatment, there is no description or suggestion of detailed conditions, and the adhesion to the matrix resin cannot necessarily be effectively enhanced. In Patent Document 2, the effect of removing fragile portions by washing with warm water is not always sufficient, and sticking cannot always be suppressed when a specific sizing agent is applied. Similarly to Patent Document 2, Patent Document 3 does not necessarily have a sufficient effect of suppressing sticking. In Patent Literature 4, although it is thought that the formation of fragile portions can be suppressed by performing the air oxidation treatment, the effect of improving the adhesive force was insufficient. In addition, Patent Document 5 requires a long time of treatment, which has the problem of lowering the tensile strength of the carbon fiber. In Patent Document 6, high adhesion cannot be found by air oxidation treatment alone, and electrolytic treatment is performed after air oxidation treatment, resulting in a problem of a multi-stage process.
　そこで本発明が解決しようとする課題は、炭素繊維の引張強度を低下させることなく、接着力に優れ、且つ特定のサイジング剤を塗布しても単繊維間の固着が生じない、高性能な炭素繊維強化複合材料を得るのに好適な炭素繊維束およびその製造方法を提供することにある。 Therefore, the problem to be solved by the present invention is to provide a high-performance carbon fiber that does not reduce the tensile strength of the carbon fiber, has excellent adhesive strength, and does not cause sticking between single fibers even when a specific sizing agent is applied. An object of the present invention is to provide a carbon fiber bundle suitable for obtaining a fiber-reinforced composite material and a method for producing the same.
　上記の課題を解決するために、本発明は、次の構成を有する。すなわち、
［１］下記の（１）または（２）を満たす炭素繊維束である。 In order to solve the above problems, the present invention has the following configurations. i.e.
[1] A carbon fiber bundle satisfying the following (1) or (2).
　（１）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長２６０ｎｍでの吸光度（Ｉ２６０ｎｍ）が０．００５以上であり、波長５５０ｎｍの吸光度と波長８００ｎｍの吸光度との比である吸光度比　（Ｉ５５０ｎｍ／Ｉ８００ｎｍ）が１．８以下であり、ループ強度σＬ（ＧＰａ）とストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）が１．７以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束である。 (1) Absorbance at a wavelength of 260 nm (I 260 nm ) is 0.005 or more, the absorbance ratio (I 550 nm /I 800 nm ), which is the ratio of the absorbance at a wavelength of 550 nm to the absorbance at a wavelength of 800 nm, is 1.8 or less, and the loop strength σ L (GPa) and the strand strength A carbon fiber bundle having a ratio (σ L /σ S ) to σ S (GPa) of 1.7 or more and an adhesive strength to LM-PAEK resin evaluated by a single fiber pull-out method of 68 MPa or more.
　（２）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長５５０ｎｍでの吸光度（Ｉ５５０ｎｍ）が０．０１５以下であり、ループ強度σＬ（ＧＰａ）とストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）が１．７以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束である。
［２］下記の（１）～（３）の少なくとも一以上を満たす炭素繊維束。
（１）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長２６０ｎｍでの吸光度（Ｉ２６０ｎｍ）が０．００５以上であり、波長５５０ｎｍの吸光度と波長８００ｎｍの吸光度との比である吸光度比（Ｉ５５０ｎｍ／Ｉ８００ｎｍ）が１．８以下であり、ループ強度σＬ（ＧＰａ）とストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）が１．７以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束。
（２）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長５５０ｎｍでの吸光度（Ｉ５５０ｎｍ）が０．０１５以下であり、ループ強度σＬ（ＧＰａ）とストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）が１．７以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束。
（３）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長５５０ｎｍでの吸光度（Ｉ５５０ｎｍ）が０．０１５以下であり、ループ強度σＬ（ＧＰａ）が８．０ＧＰａ以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束。
［３］５５０℃の空気中で３時間加熱した際の質量減少率が５０％以下である［１］または［２］に記載の炭素繊維束。
［４］酸素含有雰囲気下において７００℃以上で０．１～６秒処理する炭素繊維束の製造方法。 (2) Absorbance at a wavelength of 550 nm (I 550 nm ) is 0.015 or less, the ratio of the loop strength σ L (GPa) to the strand strength σ S (GPa) (σ L /σ S ) is 1.7 or more, and the LM evaluated by the single fiber pullout method - A carbon fiber bundle having an adhesive strength of 68 MPa or more with a PAEK resin.
[2] A carbon fiber bundle that satisfies at least one of the following (1) to (3).
(1) Absorbance at a wavelength of 260 nm (I 260 nm ) is 0.005 or more, the absorbance ratio (I 550 nm /I 800 nm ), which is the ratio of the absorbance at a wavelength of 550 nm to the absorbance at a wavelength of 800 nm, is 1.8 or less, and the loop strength σ L (GPa) and the strand strength A carbon fiber bundle having a ratio (σ L /σ S ) to σ S (GPa) of 1.7 or more and an adhesive strength to LM-PAEK resin of 68 MPa or more as evaluated by a single fiber pull-out method.
(2) Absorbance at a wavelength of 550 nm (I 550 nm ) is 0.015 or less, the ratio of the loop strength σ L (GPa) to the strand strength σ S (GPa) (σ L /σ S ) is 1.7 or more, and the LM evaluated by the single fiber pullout method - A carbon fiber bundle having an adhesive strength of 68 MPa or more with the PAEK resin.
(3) Absorbance at a wavelength of 550 nm (I 550 nm ) is 0.015 or less, the loop strength σ L (GPa) is 8.0 GPa or more, and the adhesive strength to LM-PAEK resin evaluated by the single fiber pull-out method is 68 MPa or more.
[3] The carbon fiber bundle according to [1] or [2], which has a mass reduction rate of 50% or less when heated in air at 550° C. for 3 hours.
[4] A method for producing a carbon fiber bundle, comprising treating at 700° C. or higher for 0.1 to 6 seconds in an oxygen-containing atmosphere.
　本発明によれば、炭素繊維束の引張強度を低下させることなく、接着力に優れ、且つ特定のサイジング剤を塗布しても単繊維間の固着が生じにくい、高性能な複合材料を得るのに好適な炭素繊維束およびその製造方法を提供することができる。 According to the present invention, it is possible to obtain a high-performance composite material that does not reduce the tensile strength of the carbon fiber bundle, has excellent adhesive strength, and is less likely to stick between single fibers even when a specific sizing agent is applied. It is possible to provide a carbon fiber bundle suitable for and a method for producing the same.
　以下、さらに詳しく本発明に係る炭素繊維束について説明する。 The carbon fiber bundle according to the present invention will be described in more detail below.
　本発明の炭素繊維束は、下記の（１）もしくは（２）を満たす炭素繊維束、または、下記の（１）～（３）の少なくとも一以上を満たす炭素繊維束である。 The carbon fiber bundle of the present invention is a carbon fiber bundle that satisfies (1) or (2) below, or a carbon fiber bundle that satisfies at least one or more of (1) to (3) below.
　（１）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長２６０ｎｍでの吸光度（Ｉ２６０ｎｍ）が０．００５以上であり波長５５０ｎｍの吸光度と波長８００ｎｍの吸光度との比である吸光度比　（Ｉ５５０ｎｍ／Ｉ８００ｎｍ）が１．８以下であり、ループ強度σＬ（ＧＰａ）とストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）が１．７以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束。 (1) Absorbance at a wavelength of 260 nm (I 260 nm ) is 0.005 or more, the absorbance ratio (I 550 nm /I 800 nm ), which is the ratio of the absorbance at a wavelength of 550 nm to the absorbance at a wavelength of 800 nm, is 1.8 or less, and the loop strength σ L (GPa) and the strand strength σ A carbon fiber bundle having a ratio (σ L /σ S ) to S (GPa) of 1.7 or more and an adhesive strength to LM-PAEK resin evaluated by a single fiber pull-out method of 68 MPa or more.
　（２）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長５５０ｎｍでの吸光度（Ｉ５５０ｎｍ）が０．０１５以下であり、ループ強度σＬ（ＧＰａ）とストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）が１．７以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束。 (2) Absorbance at a wavelength of 550 nm (I 550 nm ) is 0.015 or less, the ratio of the loop strength σ L (GPa) to the strand strength σ S (GPa) (σ L /σ S ) is 1.7 or more, and the LM evaluated by the single fiber pullout method - A carbon fiber bundle having an adhesive strength of 68 MPa or more with the PAEK resin.
　（３）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長５５０ｎｍでの吸光度（Ｉ５５０ｎｍ）が０．０１５以下であり、ループ強度σＬ（ＧＰａ）が８．０ＧＰａ以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束。 (3) Absorbance at a wavelength of 550 nm (I 550 nm ) is 0.015 or less, the loop strength σ L (GPa) is 8.0 GPa or more, and the adhesive strength to LM-PAEK resin evaluated by the single fiber pull-out method is 68 MPa or more.
　ここで、抽出液の溶媒としてジメチルスルホキシドを用いる理由を説明する。炭素繊維束の表面に形成される脆弱部は酸素官能基などの極性官能基を有しているものの、基本骨格は疎水性の炭素からなるため、水などでは十分に抽出されない。種々の溶剤を用いた検討の末、ジメチルスルホキシドが炭素繊維束の表面に形成される脆弱部を抽出する効果が高いことを見出した。その理由は明確ではないが、ジメチルスルホキシドはスルホン基があるため極性を有しつつ、且つ、メチル基による非極性部を有しており、炭素繊維束の表面に形成される脆弱部との親和性が良いものと解釈できる。 Here, the reason for using dimethyl sulfoxide as the solvent for the extract will be explained. Although the weak portion formed on the surface of the carbon fiber bundle has a polar functional group such as an oxygen functional group, the basic skeleton is composed of hydrophobic carbon, so it is not sufficiently extracted with water or the like. After investigations using various solvents, it was found that dimethyl sulfoxide is highly effective in extracting weak portions formed on the surface of carbon fiber bundles. Although the reason is not clear, dimethyl sulfoxide has polarity due to the sulfone group, and has a non-polar part due to the methyl group, and has an affinity with the weak part formed on the surface of the carbon fiber bundle. It can be interpreted as good.
　まず、上記（１）について説明する。 First, the above (1) will be explained.
　上記（１）において、Ｉ２６０ｎｍは、炭素繊維束の表面処理を行うことによって生成する脆弱部の内、接着力にある程度関係する脆弱部の量に対応し、大きいほど接着力が高まりやすい。そのため、Ｉ２６０ｎｍは０．００５以上とする必要がある。 In (1) above, I 260 nm corresponds to the amount of brittle portions that are related to the adhesive strength to some extent among the brittle portions generated by surface treatment of the carbon fiber bundle, and the larger I 260 nm is, the more easily the adhesive strength increases. Therefore, I260nm must be 0.005 or more.
　上記（１）において、Ｉ５５０ｎｍ／Ｉ８００ｎｍを制御することで特定のサイジング剤を付与した際の単糸間固着が抑制されることを見出した。その理由は明確ではないが、Ｉ５５０ｎｍは表面処理によって生成する脆弱部の内、特定のサイジング剤を付与した際に固着を誘発しやすい脆弱部に由来し、Ｉ８００ｎｍは固着を誘発しにくい脆弱部であると解釈することができる。そのため、表面処理によって生成する脆弱部の内、Ｉ５５０ｎｍ／Ｉ８００ｎｍが小さいほど単糸間固着が抑制され、炭素繊維強化複合材料としての高い性能が得られるものと考えることができる。また、上記（１）におけるＩ５５０ｎｍ／Ｉ８００ｎｍは１．５以下であることが好ましく、１．３以下であることがより好ましい。また、Ｉ５５０ｎｍは０．０２以下が好ましく、０．００５以下がより好ましい。また、上記（１）においてＩ８００ｎｍは０．０１以下が好ましく、０．００５以下がより好ましい。上記（１）においてＩ５５０ｎｍ／Ｉ８００ｎｍを１．８以下にするためには、例えば、後述する表面処理条件を採用することで達成することができる。 In (1) above, it was found that by controlling I 550 nm /I 800 nm , sticking between single yarns when a specific sizing agent is applied is suppressed. Although the reason is not clear, I 550nm is derived from the brittle portion that is likely to induce sticking when a specific sizing agent is applied, among the brittle portions generated by surface treatment, and I 800nm is brittle that is difficult to induce sticking. can be interpreted as a part. Therefore, it can be considered that the smaller the I 550 nm /I 800 nm of the brittle portion generated by the surface treatment, the more the adhesion between single yarns is suppressed, and the higher performance as a carbon fiber reinforced composite material can be obtained. Also, I 550 nm /I 800 nm in (1) above is preferably 1.5 or less, more preferably 1.3 or less. Also, I 550 nm is preferably 0.02 or less, more preferably 0.005 or less. In (1) above, I800nm is preferably 0.01 or less, more preferably 0.005 or less. In order to make I550nm / I800nm equal to or less than 1.8 in (1) above, it can be achieved, for example, by adopting the surface treatment conditions described later.
　次に上記（２）および（３）について説明する。継続して検討したところ、炭素繊維束の表面処理を行うことによって生成する脆弱部が極めて少ない場合には、上記（１）を満たしていない場合でも、上記（２）または（３）のいずれかを満たしていれば、本発明の意図する効果が発現することを見出した。上記（２）および（３）においてＩ５５０ｎｍは０．０１５以下である。先述のとおり、脆弱部が極めて少ない場合においてはＩ５５０ｎｍ／Ｉ８００ｎｍの分母にあたるＩ８００ｎｍが極めて小さな値やベースラインの取り方によっては負の値をとる可能性があるため、結果としてＩ５５０ｎｍ／Ｉ８００ｎｍが上記（１）で規定される範囲を逸脱することがあるが、その場合でもＩ５５０ｎｍが前記範囲であれば高い固着抑制効果を発現することを見出した。上記（２）および（３）においてＩ５５０ｎｍは０．０１以下が好ましく、０．００５以下がより好ましい。上記（２）および（３）においてＩ５５０ｎｍを０．０１５以下にするためには、例えば、後述する表面処理条件を採用することで達成することができる。 Next, the above (2) and (3) will be explained. As a result of continuous examination, when the number of weak portions generated by surface treatment of the carbon fiber bundle is extremely small, even if the above (1) is not satisfied, either the above (2) or (3) It has been found that the intended effect of the present invention is exhibited if the conditions are satisfied. In (2) and (3) above, I 550 nm is 0.015 or less. As described above, when there are very few fragile parts, I 800nm , which is the denominator of I 550nm /I 800nm , may take a very small value or a negative value depending on how the baseline is taken. Although I 800 nm may deviate from the range specified in (1) above, it was found that even in such cases, if I 550 nm is within the above range, a high anti-sticking effect is exhibited. In (2) and (3) above, I550nm is preferably 0.01 or less, more preferably 0.005 or less. In order to make I 550 nm equal to or less than 0.015 in (2) and (3) above, for example, it can be achieved by adopting the surface treatment conditions described later.
　上記（１）および（２）における炭素繊維束は、ループ強度σＬ（ＧＰａ）とストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）が１．７以上である。かかる比が大きいほど、ストランド強度に対して後述するループ強度が高いことを意味する。炭素繊維の引張強度は測定する長さに応じて変化し、短い長さで評価するほど、長さと長さあたりの欠陥の存在確率との積、すなわち欠陥の存在数の期待値が低下するため、引張強度は高くなる。ループ強度は炭素繊維をループ状に屈曲させることで極めて短い長さの範囲に選択的に引張応力を印加することのできる手法であり、欠陥の存在数の期待値が低いときの炭素繊維の引張強度を意味する。ループ強度が高いと、一方向強化複合材料の引張強度が高まりやすいことがすでに知られている（特許第５９０７３２１号）。ループ強度とストランド強度の比が前記範囲であれば、ストランド強度に対して一方向強化複合材料の引張強度が高いものとなりやすい。σＬ／σＳを１．７以上とするためには、例えば、後述する表面処理条件を採用することで達成できる。 The carbon fiber bundles in (1) and (2) above have a ratio (σ L /σ S ) of loop strength σ L (GPa) to strand strength σ S (GPa) of 1.7 or more. The larger the ratio, the higher the loop strength, which will be described later, relative to the strand strength. The tensile strength of carbon fiber changes according to the length to be measured, and the shorter the length, the lower the expected value of the product of the length and the probability of existence of defects per length, that is, the number of defects. , the tensile strength is higher. Loop strength is a method that can selectively apply tensile stress to an extremely short length range by bending carbon fibers into a loop. means strength. It is already known that high loop strength tends to increase the tensile strength of unidirectionally reinforced composite materials (Patent No. 5907321). If the ratio of the loop strength to the strand strength is within the above range, the tensile strength of the unidirectionally reinforced composite material tends to be higher than the strand strength. In order to make σ L /σ S equal to or greater than 1.7, it can be achieved, for example, by adopting the surface treatment conditions described later.
　次に上記（３）について説明する。継続して検討したところ、上記（１）または（２）のいずれをも満たしていない場合でも、上記（３）を満たしていれば、本発明の意図する効果が発現することを見出した。上記（３）における炭素繊維束のループ強度σＬ（ＧＰａ）は８．０ＧＰａ以上である。σＬが８．０ＧＰａ以上であればストランド強度σｓに多少の変動があっても一方向強化複合材料の引張強度が高いものとなりやすい。 Next, the above (3) will be described. As a result of continuous investigation, it was found that the intended effects of the present invention are exhibited as long as the above (3) is satisfied even when neither of the above (1) nor (2) is satisfied. The loop strength σ L (GPa) of the carbon fiber bundle in (3) above is 8.0 GPa or more. If σL is 8.0 GPa or more, the tensile strength of the unidirectionally reinforced composite material tends to be high even if there is some variation in strand strength σs.
　本発明の炭素繊維束は、プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である。ここで、ＬＭ－ＰＡＥＫ樹脂とは、低融点ポリアリールエーテルケトン樹脂を意味し、本発明においては、Ｖｉｃｔｒｅｘ社製“Ｖｉｃｔｒｅｘ”（登録商標）ＡＥ２５０を指すものとする。ＬＭ－ＰＡＥＫ樹脂との接着力は好ましくは７０ＭＰａ以上であり、より好ましくは７５ＭＰａ以上である。かかる接着力が大きいほど、炭素繊維強化複合材料における非繊維軸方向の強度が特に向上するが、公知技術の方法では接着力を高めても、炭素繊維表面の脆弱部が増加するか、炭素繊維の引張強度が低下する課題があった。かかる課題を回避した上で、ＬＭ－ＰＡＥＫ樹脂との接着力を６８ＭＰａ以上にするためには、例えば、後述する表面処理条件を採用することで達成できる。 The carbon fiber bundle of the present invention has an adhesive strength of 68 MPa or more with LM-PAEK resin evaluated by the pull-out method. Here, the LM-PAEK resin means a low-melting polyaryletherketone resin, and in the present invention, "Victrex" (registered trademark) AE250 manufactured by Victrex. Adhesive strength to LM-PAEK resin is preferably 70 MPa or more, more preferably 75 MPa or more. The strength in the non-fiber axial direction of the carbon fiber reinforced composite material is particularly improved as the adhesive strength increases. There was a problem that the tensile strength of In order to avoid such a problem and increase the adhesive strength to LM-PAEK resin to 68 MPa or more, it can be achieved by, for example, adopting the surface treatment conditions described later.
　本発明における炭素繊維束は、５５０℃の空気中で３時間加熱した際の質量減少率が５０％以下であることが好ましい。ここで、本発明における炭素繊維束は、公知の方法で得られた炭素繊維束を原料として（以下、原料炭素繊維束という）、例えば、特定の表面処理を行って得られた炭素繊維束のことを指す。炭素繊維束の質量減少率が上記好ましい範囲であると、原料炭素繊維束を酸化した際にσＬ（ＧＰａ）が低下し難い。そのため、質量減少率は３０％以下がより好ましく、２５％以下がさらに好ましい。 The carbon fiber bundle in the present invention preferably has a mass reduction rate of 50% or less when heated in air at 550° C. for 3 hours. Here, the carbon fiber bundle in the present invention is a carbon fiber bundle obtained by using a carbon fiber bundle obtained by a known method as a raw material (hereinafter referred to as a raw material carbon fiber bundle), for example, by performing a specific surface treatment. point to When the mass reduction rate of the carbon fiber bundle is within the preferred range, σ L (GPa) is less likely to decrease when the raw material carbon fiber bundle is oxidized. Therefore, the mass reduction rate is more preferably 30% or less, more preferably 25% or less.
　空気中で３時間加熱した際の質量減少率を抑制するためには、例えば、原料炭素繊維束の金属含有量を下記に記載の方法によって低減する方法が有効である。ここで、かかる金属含有量とは、ナトリウム、カリウム、カルシウム、鉄、亜鉛、銅の総量を指す。炭素繊維束に含まれる金属含有量は、ナトリウムおよびカリウムは原子吸光分析にて測定でき、その他の金属元素はＩＣＰ発光分析法にて測定することができる。 In order to suppress the mass reduction rate when heated in air for 3 hours, it is effective, for example, to reduce the metal content of the raw material carbon fiber bundle by the method described below. Here, the metal content refers to the total amount of sodium, potassium, calcium, iron, zinc and copper. The metal content contained in the carbon fiber bundle can be measured by atomic absorption spectrometry for sodium and potassium, and by ICP emission spectrometry for other metal elements.
　原料炭素繊維束に含まれる金属含有量を制御するためには、炭素繊維前駆体繊維の原料（重合原料）に不純物として含まれる金属元素を除去したりすることや、炭素繊維前駆体用のポリマー重合設備における反応容器や撹拌装置、配管の表面からの金属元素の溶出を抑制したりすればよい。 In order to control the metal content contained in the raw material carbon fiber bundle, it is necessary to remove metal elements contained as impurities in the raw material (polymerization raw material) of the carbon fiber precursor fiber, or to remove the polymer for the carbon fiber precursor. It is sufficient to suppress the elution of metal elements from the surfaces of reaction vessels, stirring devices, and pipes in the polymerization equipment.
　原料に不純物として含まれる金属元素を除去するには、金属元素が固体として存在している場合にはマグネットフィルターを用いたり、イオン状態を対象とする場合にはキレート剤やイオン交換樹脂を用いたりして、あらかじめ原料を処理すればよい。また、ポリアクリロニトリル（ＰＡＮ）系炭素繊維束の場合は、炭素繊維前駆体繊維用のポリマー重合の際に、レドックス系の重合開始剤として用いられることのある硫酸第一鉄七水和物などを用いないことも有効な対策の一つである。具体的には、２，２’－アゾビスイソブチロニトリル（ＡＩＢＮ）などの鉄分を成分として含まない原料を用いることが好ましい。また、重合溶媒として用いる溶媒として金属元素を含む溶媒（チオシアン酸ナトリウム、塩化亜鉛）などを用いずに、有機溶剤（ジメチルスルホキシド、ジメチルホルムアミド、ジメチルアセトアミド）を用いるのも有効な手段である。 In order to remove metal elements contained as impurities in raw materials, magnetic filters are used when metal elements exist as solids, and chelating agents and ion exchange resins are used when the metal elements are in an ionic state. Then, the raw material should be processed in advance. In the case of polyacrylonitrile (PAN) carbon fiber bundles, ferrous sulfate heptahydrate, which is sometimes used as a redox polymerization initiator, is used in the polymer polymerization for carbon fiber precursor fibers. Not using it is also one of the effective countermeasures. Specifically, it is preferable to use a raw material that does not contain iron as a component, such as 2,2'-azobisisobutyronitrile (AIBN). It is also effective to use an organic solvent (dimethylsulfoxide, dimethylformamide, dimethylacetamide) instead of a solvent containing a metal element (sodium thiocyanate, zinc chloride) as a polymerization solvent.
　また、重合設備における反応容器や撹拌装置、配管の表面からの金属元素の溶出を低減する手段としては、例えば重合設備における反応容器や撹拌装置、配管の表面をガラスやテフロンでコートしたり、ステンレス鋼表面の不動態層や表面の仕上げの状態を良好に保ったりすることで、ＰＡＮ系重合体溶液に金属元素が溶出することを防ぐ保護層を形成することが好ましい。また、炭素繊維束の製造工程において、使用する水なども金属含有量ができるだけ少ないものを用いるのも有効な手段である。 In addition, as means for reducing the elution of metal elements from the surfaces of reaction vessels, stirring devices, and piping in polymerization equipment, for example, the surfaces of reaction vessels, stirring devices, and piping in polymerization equipment are coated with glass or Teflon, and stainless steel is used. It is preferable to form a protective layer that prevents metal elements from eluting into the PAN-based polymer solution by maintaining a good passivation layer on the surface of the steel and a good surface finish. It is also an effective means to use water having a metal content as low as possible in the carbon fiber bundle manufacturing process.
　次に、本発明の炭素繊維束の製造方法ついて説明する。 Next, the method for producing the carbon fiber bundle of the present invention will be explained.
　本発明の炭素繊維束の製造方法は、酸素含有雰囲気下において７００℃以上で０．１～６秒処理することを特徴とする。すなわち、例えば原料炭素繊維束を酸素含有雰囲気下において７００℃以上で０．１～６秒処理することで本発明の炭素繊維束を得ることができる。原料炭素繊維束は、例えば、ＰＡＮ系、レーヨン系およびピッチ系の原料炭素繊維束が挙げられる。なかでも、強度と弾性率のバランスに優れたＰＡＮ系炭素繊維束が原料として好ましく用いられる。原料となるＰＡＮ系炭素繊維束は公知の方法で得ればよく、かかる原料炭素繊維束を表面処理する工程として、原料炭素繊維束を酸素含有雰囲気下において７００℃以上で０．１～６秒処理する。かかる処理には例えば、原料炭素繊維束を導入可能な出入口を有した加熱炉を用い、原料炭素繊維束を通過させることで処理を行う。かかる処理時間は、加熱炉の炉長を変更して調整してもよいし、通過させる炭素繊維束の速度を変更して調整してもよい。また、加熱処理は複数の加熱炉を設置して多段で行ってもよい。 The method for producing a carbon fiber bundle of the present invention is characterized by processing at 700°C or higher for 0.1 to 6 seconds in an oxygen-containing atmosphere. That is, for example, the carbon fiber bundle of the present invention can be obtained by treating a raw material carbon fiber bundle in an oxygen-containing atmosphere at 700° C. or higher for 0.1 to 6 seconds. Examples of raw carbon fiber bundles include PAN-based, rayon-based, and pitch-based raw carbon fiber bundles. Among them, PAN-based carbon fiber bundles are preferably used as a raw material because they have an excellent balance between strength and elastic modulus. The raw material PAN-based carbon fiber bundle may be obtained by a known method. As a step of surface-treating the raw material carbon fiber bundle, the raw material carbon fiber bundle is heated at 700° C. or higher in an oxygen-containing atmosphere for 0.1 to 6 seconds. process. For such a treatment, for example, a heating furnace having an entrance through which the raw material carbon fiber bundle can be introduced is used, and the raw material carbon fiber bundle is passed through the heating furnace. Such treatment time may be adjusted by changing the furnace length of the heating furnace, or by changing the speed of the carbon fiber bundles to be passed. Further, the heat treatment may be performed in multiple stages by installing a plurality of heating furnaces.
　本発明における酸素含有雰囲気とは、空気および／または酸素あるいは複数種の混合ガスを含む雰囲気であり、不活性ガスであるアルゴン、窒素などを混合して炉内の酸素濃度を制御してもよいが、操業性の観点から空気を用いることが好ましい。空気酸化の公知文献（例えば、特許文献４～６）の実施例では、加熱温度４７０℃～６５０℃となっており、従来この温度域が重要と考えられていることが伺える。この温度域では十分な接着力は発現しないものの、確かに、σＬ（ＧＰａ）の低下が生じにくく、また、かかる温度域において低温ほどσＬ（ＧＰａ）が低下しにくい。そのため、加熱処理の温度をかかる温度域よりも更に高めるとσＬ（ＧＰａ）が低下することが公知文献から想定される。 The oxygen-containing atmosphere in the present invention is an atmosphere containing air and/or oxygen or a mixed gas of a plurality of kinds, and the oxygen concentration in the furnace may be controlled by mixing an inert gas such as argon or nitrogen. However, it is preferable to use air from the viewpoint of operability. In the examples of the air oxidation known documents (for example, Patent Documents 4 to 6), the heating temperature is 470° C. to 650° C., and it can be seen that this temperature range is conventionally considered important. In this temperature range , although sufficient adhesive strength is not exhibited, it is true that σ L (GPa) is less likely to decrease. Therefore, it is assumed from the known literature that σ L (GPa) decreases when the temperature of the heat treatment is further increased beyond this temperature range.
　一方、７００℃以上の温度域でもその処理時間を極めて短くすることでσＬ（ＧＰａ）が維持され、また、驚くべきことに、公知技術よりも高い接着力を発現することを見出した。処理時間が極めて短い場合は、加熱温度が高いほど高い接着力を発現することができるが、省エネルギーの観点から、加熱温度は、８００～１，４００℃が好ましく、８００～１，２００℃がより好ましく、９００～１，０００℃が更に好ましい。加熱処理時間は加熱処理温度に応じて適宜変更することが好ましいが、生産性を高める観点からは短い方が良く、０．１～３秒が好ましく、０．１～２秒がより好ましい。 On the other hand, it was found that σ L (GPa) can be maintained even in a temperature range of 700° C. or higher by shortening the treatment time, and surprisingly, a higher adhesive strength than that of the known technology is exhibited. When the treatment time is extremely short, the higher the heating temperature, the higher the adhesive strength can be expressed, but from the viewpoint of energy saving, the heating temperature is preferably 800 to 1,400 ° C., more preferably 800 to 1,200 ° C. Preferably, 900 to 1,000°C is more preferable. The heat treatment time is preferably changed appropriately according to the heat treatment temperature, but from the viewpoint of improving productivity, the shorter the better, preferably 0.1 to 3 seconds, more preferably 0.1 to 2 seconds.
　本発明における炭素繊維束としては、繊度が０．４～３．０ｇ／ｍが好ましく、フィラメント数は１，０００～１００，０００本が好ましく、３，０００～５０，０００本がより好ましい。また、ストランド強度は１～１０ＧＰａが好ましく、３～１０ＧＰａがより好ましい。ストランド弾性率は２００～１，０００ＧＰａが好ましく、２００～５００ＧＰａがより好ましい。 The carbon fiber bundle in the present invention preferably has a fineness of 0.4 to 3.0 g/m and a filament number of preferably 1,000 to 100,000, more preferably 3,000 to 50,000. Further, the strand strength is preferably 1 to 10 GPa, more preferably 3 to 10 GPa. The strand elastic modulus is preferably 200 to 1,000 GPa, more preferably 200 to 500 GPa.
　次に、実施例により本発明を具体的に説明するが、本発明はこれらの実施例により制限されるものではない。 Next, the present invention will be described in detail with reference to examples, but the present invention is not limited by these examples.
　［波長２６０ｎｍでの吸光度（Ｉ２６０ｎｍ）、波長５５０ｎｍでの吸光度（Ｉ５５０ｎｍ）、波長８００ｎｍでの吸光度（Ｉ８００ｎｍ）、波長５５０ｎｍの吸光度と波長８００ｎｍの吸光度との比である吸光度比　（Ｉ５５０ｎｍ／Ｉ８００ｎｍ）］
　紫外可視吸光度は、下記の吸光度の測定方法によって測定した。炭素繊維束を約１ｍ（約０．８ｇ）カットし、直径が約１～２ｃｍ程度のかせ巻きとし、結び目の空間を１～３ｍｍ程度残して、ガラス製のスクリュー瓶に入れ、ジメチルスルホキシド（富士フィルム和光純薬社製、特級）を炭素繊維束質量が７質量％になるように約１１ｇ加えることで炭素繊維束をジメチルスルホキシドに浸漬させた。炭素繊維束とジメチルスルホキシドの入ったガラス製のスクリュー瓶を超音波照射装置（Ｂｒａｎｓｏｎｉｃ（登録商標）　ＣＰＸ５８００－Ｊ）に導入し、発振周波数４０ｋＨｚ、高周波出力１６０Ｗ、２５℃の条件で１０分間超音波処理を施した。超音波照射後、ガラス製のスクリュー瓶の中の上澄みの液を抽出液サンプルとして、紫外可視分光光度計（ＪＡＳＣＯ、Ｖ－５５０）により、波長２６０ｎｍでの吸光度（Ｉ２６０ｎｍ）、波長５５０ｎｍの吸光度（Ｉ５５０ｎｍ）、波長８００ｎｍの吸光度（Ｉ８００ｎｍ）をそれぞれ測定した。吸光度測定は３回測定を行い、各波長における吸光度は３回の平均値を用いた。波長５５０ｎｍの吸光度と波長８００ｎｍの吸光度との比である吸光度比（Ｉ５５０ｎｍ／Ｉ８００ｎｍ）はＩ５５０ｎｍをＩ８００ｎｍで除して求めた。 [Absorbance at a wavelength of 260 nm (I 260 nm ), absorbance at a wavelength of 550 nm (I 550 nm ), absorbance at a wavelength of 800 nm (I 800 nm ), absorbance ratio (I 550 nm / I800nm )]
The ultraviolet-visible absorbance was measured by the following method for measuring absorbance. Cut about 1 m (about 0.8 g) of the carbon fiber bundle, roll it into a skein with a diameter of about 1 to 2 cm, leave a knot space of about 1 to 3 mm, put it in a glass screw bottle, and add dimethyl sulfoxide (Fuji About 11 g of film (manufactured by Wako Pure Chemical Industries, Ltd., special grade) was added so that the carbon fiber bundle mass became 7% by mass, thereby immersing the carbon fiber bundle in dimethyl sulfoxide. A glass screw bottle containing carbon fiber bundles and dimethyl sulfoxide is introduced into an ultrasonic irradiation device (Bransonic (registered trademark) CPX5800-J), and ultrasonic waves are applied for 10 minutes under the conditions of an oscillation frequency of 40 kHz, a high frequency output of 160 W, and 25 ° C. processed. After ultrasonic irradiation, the supernatant liquid in the glass screw bottle was used as an extract sample, and the absorbance at a wavelength of 260 nm (I 260 nm ) and the absorbance at a wavelength of 550 nm were measured using a UV-visible spectrophotometer (JASCO, V-550). (I 550 nm ) and absorbance (I 800 nm ) at a wavelength of 800 nm were measured. The absorbance was measured three times, and the absorbance at each wavelength was the average value of the three times. The absorbance ratio ( I550nm / I800nm ), which is the ratio of the absorbance at a wavelength of 550 nm to the absorbance at a wavelength of 800 nm, was obtained by dividing I550 nm by I800 nm .
　［ループ強度σＬ（ＧＰａ）、ループ強度σＬ（ＧＰａ）とストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）］
　本発明において、炭素繊維樹脂含浸ストランドの引張強度（ストランド強度σＳ（ＧＰａ））およびループ強度σＬ（ＧＰａ）の評価に必要なストランドの引張弾性率（ストランド弾性率Ｅ）は、ＪＩＳ Ｒ　７６０８（２００８）「樹脂含浸ストランド試験法」に従って求め、ストランド弾性率Ｅは歪み範囲０．１～０．６％の範囲で測定した。なお、試験片は、次の樹脂組成物を炭素繊維束に含浸し、１３０℃の温度で３５分間熱処理の硬化条件により作製した。 [Loop strength σ L (GPa), ratio of loop strength σ L (GPa) to strand strength σ S (GPa) (σ L /σ S )]
In the present invention, the tensile strength (strand strength σ S (GPa)) and loop strength σ L (GPa) of the carbon fiber resin-impregnated strand are required for evaluation. (2008) "Resin impregnated strand test method", and the strand elastic modulus E was measured in the strain range of 0.1 to 0.6%. The test piece was prepared by impregnating a carbon fiber bundle with the following resin composition and subjecting it to curing conditions of heat treatment at a temperature of 130° C. for 35 minutes.
　（樹脂組成）
・３，４－エポキシシクロヘキシルメチル－３，４－エポキシ－シクロヘキサン－カルボキシレート（１００質量部）
・３フッ化ホウ素モノエチルアミン（３質量部）
・アセトン（４質量部）。 (resin composition)
· 3,4-epoxycyclohexylmethyl-3,4-epoxy-cyclohexane-carboxylate (100 parts by mass)
・ Boron trifluoride monoethylamine (3 parts by mass)
- Acetone (4 parts by mass).
　また、引張試験の測定本数は６本とし、各測定結果の平均値をその炭素繊維束のストランド弾性率Ｅおよびストランド強度σＳ（ＧＰａ）とした。なお、後述の実施例および比較例においては、上記の３，４－エポキシシクロヘキシルメチル－３，４－エポキシ－シクロヘキサン－カルボキシレートとして、ユニオンカーバイド（株）製、“ＢＡＫＥＬＩＴＥ”（登録商標）ＥＲＬ－４２２１（あるいは同等品の“セロキサイド”（登録商標）２０２１Ｐ（株式会社ダイセル製））を用いた。ひずみは伸び計を用いて測定した。 Also, the number of measurements in the tensile test was 6, and the average value of each measurement result was taken as the strand elastic modulus E and strand strength σ S (GPa) of the carbon fiber bundle. In Examples and Comparative Examples described later, "BAKELITE" (registered trademark) ERL- 4221 (or equivalent "Celoxide" (registered trademark) 2021P (manufactured by Daicel Corporation)) was used. Strain was measured using an extensometer.
　ループ強度σＬ（ＧＰａ）は次の方法により評価した。すなわち、長さ約１０ｃｍの単繊維をスライドガラス上に置き、中央部に水を１～２滴たらして単繊維両端部を繊維周方向に軽くねじることで単繊維中央部にループを作り、その上にカバーガラスを置いた。これを顕微鏡のステージに設置し、トータル倍率が１００倍、フレームレートが１５フレーム／秒の条件で動画撮影を行った。ループが視野から外れないようにステージを都度調節しながら、ループさせた繊維の両端を指でスライドガラス方向に押しつけつつ逆方向に一定速度で引っ張ることで、単繊維が破断するまで歪をかけた。コマ送りにより破断直前のフレームを特定し、画像解析により破断直前のループの横幅Ｗ（μｍ）を測定した。繊維径ｄ（μｍ）を破断直前のループの横幅Ｗで除してｄ／Ｗを算出した。 The loop strength σ L (GPa) was evaluated by the following method. That is, a monofilament having a length of about 10 cm is placed on a slide glass, 1-2 drops of water are dropped on the central portion, and both ends of the monofilament are lightly twisted in the fiber circumferential direction to form a loop in the central portion of the monofilament. A cover glass was placed over it. This was installed on the stage of a microscope, and moving images were taken under conditions of a total magnification of 100 times and a frame rate of 15 frames/second. While adjusting the stage each time so that the loop did not fall out of the field of view, strain was applied until the single fiber broke by pressing both ends of the looped fiber toward the glass slide and pulling it in the opposite direction at a constant speed. . A frame immediately before the breakage was identified by frame advance, and the width W (μm) of the loop immediately before the breakage was measured by image analysis. d/W was calculated by dividing the fiber diameter d (μm) by the width W of the loop immediately before breaking.
　試験を２０回行い、ｄ／Ｗの平均値を求め、その値にストランド弾性率Ｅを乗ずることにより、すなわち、Ｅ×ｄ／Ｗにより求められる値をループ強度σＬ（ＧＰａ）とした。また、かかるループ強度σＬ（ＧＰａ）と前記ストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）を得た。ここで、繊維径ｄはＪＩＳ　Ｒ　７６０７（２０００年）に準じて測定した。具体的には、測定する多数本の炭素フィラメントからなる炭素繊維束について、単位長さ当たりの質量Ａｆ（ｇ／ｍ）および比重Ｂｆ（－）を求めた。求めたＡｆおよびＢｆの値ならびに測定する炭素繊維束のフィラメント数Ｃｆから、炭素繊維束の繊維径ｄ（μｍ）を、下記式１で算出した。 The test was performed 20 times, the average value of d/W was obtained, and the value was multiplied by the strand elastic modulus E, that is, the value obtained by E×d/W was defined as the loop strength σ L (GPa). Also, the ratio (σ L /σ S ) between the loop strength σ L (GPa) and the strand strength σ S (GPa) was obtained. Here, the fiber diameter d was measured according to JIS R 7607 (2000). Specifically, the mass A f (g/m) per unit length and the specific gravity B f (−) were determined for the carbon fiber bundle composed of a large number of carbon filaments to be measured. The fiber diameter d (μm) of the carbon fiber bundle was calculated by the following formula 1 from the obtained values of A f and B f and the number of filaments C f of the carbon fiber bundle to be measured.
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　＜ＬＭ－ＰＡＥＫ樹脂との接着力＞
　ＬＭ－ＰＡＥＫ樹脂との接着力評価は単繊維プルアウト法により測定する。本発明においては（株）寿エンジニアリング製の界面評価装置（３０９３－１０００）を用いた。ＬＭ－ＰＡＥＫ樹脂（Ｖｉｃｔｒｅｘ社製“Ｖｉｃｔｒｅｘ”（登録商標）ＡＥ２５０）を熱プレスにより板状とし、カットすることで測定に用いるＬＭ－ＰＡＥＫ樹脂を得た。カットした板状のＬＭ－ＰＡＥＫ樹脂を、加熱ステージの上に乗せ、３７０℃の温度に加熱することで溶融させた。 <Adhesive strength with LM-PAEK resin>
Adhesive strength evaluation with LM-PAEK resin is measured by a single fiber pull-out method. In the present invention, an interface evaluation device (3093-1000) manufactured by Kotobuki Engineering Co., Ltd. was used. LM-PAEK resin (“Victrex” (registered trademark) AE250 manufactured by Victrex) was made into a plate by hot pressing and cut to obtain LM-PAEK resin used for measurement. The cut plate-shaped LM-PAEK resin was placed on a heating stage and heated to a temperature of 370° C. to melt it.
　溶融させたＬＭ－ＰＡＥＫ樹脂に炭素繊維束の中から取り出した単糸を、マイクロメーターを用いて約４０μｍの埋め込み深さを狙ってＬＭ－ＰＡＥＫ樹脂中に埋め込み、室温まで冷却することでＬＭ－ＰＡＥＫ樹脂に単糸を埋め込んだサンプルを調製した。埋め込んだサンプルをロードセルにセットし、単糸をＬＭ－ＰＡＥＫ樹脂から引き抜いた際の最大荷重（ｇ）、埋め込みの実深さ（μｍ）を測定した。 A single yarn taken out from the carbon fiber bundle is embedded in the melted LM-PAEK resin with a micrometer aiming at an embedding depth of about 40 μm, and cooled to room temperature. A sample was prepared in which the monofilament was embedded in PAEK resin. The embedded sample was set in a load cell, and the maximum load (g) and the actual embedding depth (μm) when the single yarn was pulled out from the LM-PAEK resin were measured.
　引き抜きの際の引き抜きの速度は１．０μｍ／ｓとした。ここで、埋め込みの実深さは、引き抜きを初め、加重が加わり始めた点から、糸が樹脂中から引き抜かれ、荷重が無くなるまでの点までの距離から得た。得られた最大荷重および埋め込みの実深さ（μｍ）から、以下の式２に基づき、接着力（ＭＰａ）を算出した。 The drawing speed during drawing was set to 1.0 μm/s. Here, the actual depth of burying was obtained from the distance from the point at which the load started to be applied at the beginning of pulling out to the point at which the load was removed after the thread was pulled out of the resin. The adhesive strength (MPa) was calculated from the obtained maximum load and actual embedding depth (μm) based on Equation 2 below.
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　ここで、繊維径ｄ（μｍ）は前記式１に基づき求めた値である。 Here, the fiber diameter d (μm) is the value obtained based on the above formula 1.
　＜空気中で３時間加熱した際の質量減少率＞
　炭素繊維束約３ｇをセラミックるつぼに入れ、予め５５０℃に熱した電気炉内に導入し、３時間加熱処理を行った。３時間加熱処理した後、電気炉より炭素繊維束の入ったセラミックるつぼを取り出し、炭素繊維束の質量を測定した。空気中で３時間加熱した際の質量減少率（％）は下記の式３により算出した。 <Mass reduction rate when heated in air for 3 hours>
About 3 g of a carbon fiber bundle was placed in a ceramic crucible, introduced into an electric furnace preheated to 550° C., and heat-treated for 3 hours. After heat treatment for 3 hours, the ceramic crucible containing the carbon fiber bundle was taken out from the electric furnace, and the mass of the carbon fiber bundle was measured. The mass reduction rate (%) when heated in air for 3 hours was calculated by the following formula 3.
Figure JPOXMLDOC01-appb-M000003
Figure JPOXMLDOC01-appb-M000003
　＜金属含有量＞
　炭素繊維束約０．７ｇをプラズマリアクターで低温灰化処理を行い、得られたサンプルを希硝酸に溶解することで測定サンプルとした。測定サンプルにおいて、ナトリウムおよびカリウムの量は原子吸光分析にて測定し、その他の金属元素はＩＣＰ発光分析法にて測定し、ナトリウム、カリウム、カルシウム、鉄、亜鉛、アルミニウム、マグネシウムの合計量を金属含有量とした。 <Metal content>
About 0.7 g of the carbon fiber bundle was subjected to low-temperature ashing treatment in a plasma reactor, and the obtained sample was dissolved in dilute nitric acid to obtain a measurement sample. In the measurement sample, the amount of sodium and potassium was measured by atomic absorption spectrometry, other metal elements were measured by ICP emission spectrometry, and the total amount of sodium, potassium, calcium, iron, zinc, aluminum, and magnesium was determined as metal content.
　＜サイジング剤付与後の固着数＞ 
　ポリエチレンイミン（ＢＡＳＦジャパン（株）製　“Ｌｕｐａｓｏｌ”（登録商標）Ｇ２０　Ｗａｔｅｒ－ｆｒｅｅ）を水に溶解させた約０．６質量％の水溶液を得た。この水溶液をサイジング剤水溶液として用い、浸漬法によりサイジング剤を表面処理された炭素繊維束に塗布した後、予備乾燥工程としてホットローラーで１２０℃の温度で３０秒間熱処理をし、続いて、第２乾燥工程として２２０℃の温度の加熱空気中で１３５秒間熱処理をして、サイジング剤塗布炭素繊維束を得た。 <Number of fixation after application of sizing agent>
An aqueous solution of about 0.6% by mass was obtained by dissolving polyethyleneimine (“Lupasol” (registered trademark) G20 Water-free, manufactured by BASF Japan Ltd.) in water. Using this aqueous solution as a sizing agent aqueous solution, the sizing agent is applied to the surface-treated carbon fiber bundle by an immersion method, and then heat treated with a hot roller at a temperature of 120 ° C. for 30 seconds as a preliminary drying step. As a drying step, heat treatment was performed in heated air at a temperature of 220° C. for 135 seconds to obtain a sizing agent-coated carbon fiber bundle.
　サイジング剤の付着量は、表面処理されたサイジング剤塗布炭素繊維束全量１００質量部に対して、０．３０質量部となるように調整した。その後、以下に述べる方法により固着数を評価した。１００ｇの水にアニオン系界面活性剤であるジオクチルスルホこはく酸ナトリウム（東京化成工業株式会社製）を０．０５質量％となるように溶解し、分散媒とした。回転数２００ｒｐｍのマグネティックスターラーにより攪拌しておいた分散媒に、長さ５ｍｍに裁断した測定対象の炭素繊維束を投入した。３０秒間攪拌したあと、吸引ろ過を行い、ろ過後のろ紙は風の当たらない場所に２時間静置して風乾した。 The amount of the sizing agent applied was adjusted to 0.30 parts by mass with respect to 100 parts by mass of the total surface-treated carbon fiber bundle coated with the sizing agent. After that, the number of fixation was evaluated by the method described below. Sodium dioctyl sulfosuccinate (manufactured by Tokyo Kasei Kogyo Co., Ltd.), which is an anionic surfactant, was dissolved in 100 g of water to a concentration of 0.05% by mass to prepare a dispersion medium. A carbon fiber bundle to be measured cut to a length of 5 mm was put into the dispersion medium which had been stirred by a magnetic stirrer rotating at 200 rpm. After stirring for 30 seconds, suction filtration was performed, and the filter paper after filtration was allowed to stand for 2 hours in a place not exposed to wind and air-dried.
　かかるろ紙をラミネートフィルムで挟み、ラミネーターを通すことによりラミネート加工した。ラミネート加工されたろ紙の表面を光学顕微鏡にてろ紙全域を撮影した。本発明においては、単糸が複数本平行に集合し、かつ隙間無く接した状態であるために１本の太い繊維であるかのように見えるかたまりであって、太さが４０μｍ以上であるものを固着と定義した。固着であるかどうかの判断に際しては、明らかに基準を超えるものは目視で判断し、太さが４０μｍ近傍であるなど目視での判断が困難なものについては、画像処理ソフトを用いて直径を計測し、判断した。 The filter paper was sandwiched between laminated films and passed through a laminator for lamination. The entire surface of the laminated filter paper was photographed with an optical microscope. In the present invention, a lump having a thickness of 40 μm or more that looks like a single thick fiber because a plurality of single yarns are gathered in parallel and in contact with each other without gaps. was defined as sticking. When judging whether or not it is stuck, visually judge if it clearly exceeds the standard, and measure the diameter using image processing software if it is difficult to judge visually such as the thickness is around 40 μm. and decided.
　画像処理はオープンソースのソフトウェアであるｉｍａｇｅＪ（イメージ・ジェイ）を用いて次のように行った。まず解析対象の画像をｉｍａｇｅＪに読み込み、直径を計測したい単糸のかたまりの長軸を２等分する位置を通り、かつ長軸と直交する線分を引き、「Ａｎａｌｙｚｅ」コマンドの「Ｐｌｏｔ　ｐｒｏｆｉｌｅ」を選択することにより、線分に沿った輝度のプロファイルを取得した。かかるプロファイルの半値幅を読み取り、実寸に換算したものをかかる単糸のかたまりの「太さ」とし、これが４０μｍ以上であれば固着と判断した。 Image processing was performed using the open source software imageJ as follows. First, load the image to be analyzed into imageJ, draw a line segment that passes through the position that bisects the long axis of the single yarn mass whose diameter you want to measure and is perpendicular to the long axis, and select "Plot profile" of the "Analyze" command. By selecting , the intensity profile along the line segment was obtained. The half-value width of the profile was read, and the actual size was converted into the "thickness" of the bundle of single yarns.
　表１および２に実施例および比較例の結果を示した。 Tables 1 and 2 show the results of Examples and Comparative Examples.
　（実施例１）
　炭素繊維前駆体用のポリマーの重合を、金属元素を含まないジメチルスルホキシド中で行い、金属含有量が３０ｐｐｍとなった原料炭素繊維束（フィラメント数１２，０００、ストランド強度４．９ＧＰａ、弾性率２３０ＧＰａ、繊維径６．９μｍ）を、７５０℃で６秒間、空気雰囲気中にて酸化処理を行った。σＬ／σＳは２．３であり、表面処理を行っていない比較例１と殆ど変わらなかった。また、５５０℃の空気中で３時間加熱した際の質量減少率は１９％であり、金属含有量の多い実施例６よりも小さく、また、σＬおよびσＬ／σＳは実施例６よりも高かった。ＬＭ－ＰＡＥＫ樹脂との接着力は７１ＭＰａ発現した。加熱温度の低い比較例２および３と比較して、ＬＭ－ＰＡＥＫ樹脂との接着力は高かった。サイジング剤付与後の固着数は３個であり、比較例５および６と比較して大幅に少なかった。 (Example 1)
Polymerization of the polymer for the carbon fiber precursor was carried out in dimethyl sulfoxide containing no metal element, and a raw material carbon fiber bundle with a metal content of 30 ppm (number of filaments: 12,000, strand strength: 4.9 GPa, elastic modulus: 230 GPa , fiber diameter 6.9 μm) was subjected to oxidation treatment at 750° C. for 6 seconds in an air atmosphere. σ L /σ S was 2.3, which was almost the same as Comparative Example 1 without surface treatment. In addition, the mass reduction rate when heated in air at 550 ° C. for 3 hours is 19%, which is smaller than that of Example 6 with a high metal content, and σ L and σ L /σ S are higher than those of Example 6. was also expensive. The adhesive strength with LM-PAEK resin was 71 MPa. Compared to Comparative Examples 2 and 3 with low heating temperatures, the adhesion to LM-PAEK resin was high. The number of fixation after application of the sizing agent was 3, which was significantly less than in Comparative Examples 5 and 6.
　（実施例２）
　加熱温度を１，２００℃に変更し、処理時間を０．１秒とした以外は実施例１と同様の方法にて酸化処理を行った。ＬＭ－ＰＡＥＫ樹脂との接着力は７３ＭＰａ発現した。加熱温度の低い比較例２および３と比較して、ＬＭ－ＰＡＥＫ樹脂との接着力は高かった。 (Example 2)
The oxidation treatment was performed in the same manner as in Example 1 except that the heating temperature was changed to 1,200° C. and the treatment time was set to 0.1 second. The adhesive strength with LM-PAEK resin was 73 MPa. Compared to Comparative Examples 2 and 3 with low heating temperatures, the adhesion to LM-PAEK resin was high.
　（実施例３）
　加熱温度を８００℃に変更し、処理時間を３秒とした以外は実施例１と同様の方法にて酸化処理を行った。Ｉ５５０ｎｍ/Ｉ８００ｎｍは１．３であり、比較例５および６と比較して小さかった。サイジング剤付与後の固着数は２個であり、比較例５および６と比較して大幅に少なかった。また、σＬは１１．０ＧＰａ、σＬ／σＳは２．２であり、処理時間の長い比較例４よりも高かった。 (Example 3)
The oxidation treatment was performed in the same manner as in Example 1, except that the heating temperature was changed to 800° C. and the treatment time was set to 3 seconds. I 550 nm /I 800 nm was 1.3, which was small compared to Comparative Examples 5 and 6. The number of fixation after application of the sizing agent was 2, which was significantly less than in Comparative Examples 5 and 6. In addition, σ L was 11.0 GPa and σ L /σ S was 2.2, which were higher than Comparative Example 4 in which the treatment time was long.
　（実施例４）
　加熱温度を９５０℃に変更し、処理時間を０．７秒とした以外は実施例１と同様の方法にて酸化処理を行った。ＬＭ－ＰＡＥＫ樹脂との接着力は７５ＭＰａ発現した。実施例１よりもＬＭ－ＰＡＥＫ樹脂との接着力が向上した。 (Example 4)
The oxidation treatment was performed in the same manner as in Example 1 except that the heating temperature was changed to 950° C. and the treatment time was set to 0.7 seconds. An adhesive strength of 75 MPa was exhibited with the LM-PAEK resin. Adhesion to LM-PAEK resin was improved more than in Example 1.
　（実施例５）
　加熱温度を１，０００℃に変更した以外は実施例４と同様の方法にて酸化処理を行った。ＬＭ－ＰＡＥＫ樹脂との接着力は７９ＭＰａ発現した。実施例４よりもＬＭ－ＰＡＥＫ樹脂との接着力が向上した。 (Example 5)
The oxidation treatment was performed in the same manner as in Example 4, except that the heating temperature was changed to 1,000°C. The adhesive strength with LM-PAEK resin was 79 MPa. Adhesion to LM-PAEK resin was improved more than in Example 4.
　（実施例６）
　炭素繊維前駆体用のポリマーの重合を、金属元素を含むチオシアン酸ナトリウム水溶液中で行い、金属含有量が１，０００ｐｐｍとなった原料炭素繊維束を用いた以外は実施例１と同様の方法にて酸化処理を行った。５５０℃の空気中で３時間加熱した際の質量減少率は５５％であり、金属含有量の少ない実施例１よりも大きく、また、σＬは９．５ＧＰａ、σＬ／σＳは１．９と実施例１よりも小さかった。 (Example 6)
Polymerization of the polymer for the carbon fiber precursor was carried out in a sodium thiocyanate aqueous solution containing a metal element, and the same method as in Example 1 was used except that a raw material carbon fiber bundle with a metal content of 1,000 ppm was used. oxidation treatment. The mass reduction rate when heated in air at 550° C. for 3 hours was 55%, which is larger than Example 1 with a small metal content . 9 and Example 1 were smaller.
　（実施例７）
　加熱温度を１，０００℃に変更し、処理時間を１．３秒とした以外は実施例１と同様の方法にて酸化処理を行った。ＬＭ－ＰＡＥＫ樹脂との接着力は７９ＭＰａ発現した。Ｉ５５０ｎｍは０．００２であり、また、Ｉ８００ｎｍは０．００１と極めて小さかった。Ｉ８００ｎｍが極めて小さいため、Ｉ５５０ｎｍ/Ｉ８００ｎｍは２．０と高い値を示すが、Ｉ５５０ｎｍが小さいためサイジング剤付与後の固着数は１個であり、比較例５および６と比較して大幅に少なかった。 (Example 7)
The oxidation treatment was performed in the same manner as in Example 1 except that the heating temperature was changed to 1,000° C. and the treatment time was set to 1.3 seconds. The adhesive strength with LM-PAEK resin was 79 MPa. I 550 nm was 0.002, and I 800 nm was 0.001, which is extremely small. Since I 800 nm is extremely small, I 550 nm /I 800 nm shows a high value of 2.0. was significantly less.
　（実施例８）
　加熱温度を１，１００℃に変更し、処理時間を０．７秒とした以外は実施例１と同様の方法にて酸化処理を行った。ＬＭ－ＰＡＥＫ樹脂との接着力は７８ＭＰａ発現した。Ｉ５５０ｎｍは０．００３であり、また、Ｉ８００ｎｍは０．００１と極めて小さかった。Ｉ８００ｎｍが極めて小さいため、Ｉ５５０ｎｍ/Ｉ８００ｎｍは３．０と高い値を示すが、Ｉ５５０ｎｍが小さいためサイジング剤付与後の固着数は２個であり、比較例５および６と比較して大幅に少なかった。 (Example 8)
The oxidation treatment was performed in the same manner as in Example 1 except that the heating temperature was changed to 1,100° C. and the treatment time was set to 0.7 seconds. The adhesive strength with LM-PAEK resin was 78 MPa. I 550 nm was 0.003, and I 800 nm was 0.001, which is extremely small. Since I 800 nm is extremely small, I 550 nm /I 800 nm shows a high value of 3.0. was significantly less.
　（実施例９）
　加熱温度を９００℃に変更し、処理時間を２．６秒とした以外は実施例１と同様の方法にて酸化処理を行った。ＬＭ－ＰＡＥＫ樹脂との接着力は７７ＭＰａ発現した。Ｉ５５０ｎｍは０．００４であり、また、Ｉ８００ｎｍは０．００１と極めて小さかった。Ｉ８００ｎｍが極めて小さいため、Ｉ５５０ｎｍ/Ｉ８００ｎｍは４．０と高い値を示すが、Ｉ５５０ｎｍが小さいためサイジング剤付与後の固着数は２個であり、比較例５および６と比較して大幅に少なかった。
（実施例１０）
　実施例１と同様の条件で作製した前駆体ポリマーを用いて、製糸/焼成条件を変更して得た原料炭素繊維束（フィラメント数２４，０００、ストランド強度６．３ＧＰａ、弾性率２９４ＧＰａ、繊維径５．４μｍ）を、１，１００℃で２秒間、空気雰囲気中にて酸化処理を行った。σＬは１０．２ＧＰａであり、σＬ／σＳは１．６であった。ＬＭ－ＰＡＥＫ樹脂との接着力は７８ＭＰａ発現し、固着数は２個であった。
（実施例１１）
　実施例１と同様の条件で作製した前駆体ポリマーを用いて、製糸/焼成条件を変更して得た原料炭素繊維束（フィラメント数１２，０００、ストランド強度４．０ＧＰａ、弾性率２３０ＧＰａ、繊維径６．９μｍ）を、１，０００℃で６秒間、空気雰囲気中にて酸化処理を行った。σＬは７．６ＧＰａであり、σＬ／σＳは１．９であった。ＬＭ－ＰＡＥＫ樹脂との接着力は７８ＭＰａ発現し、固着数は３個であった。 (Example 9)
The oxidation treatment was performed in the same manner as in Example 1 except that the heating temperature was changed to 900° C. and the treatment time was set to 2.6 seconds. The adhesive strength with LM-PAEK resin was 77 MPa. I 550 nm was 0.004, and I 800 nm was 0.001, which is extremely small. Since I 800 nm is extremely small, I 550 nm /I 800 nm shows a high value of 4.0. was significantly less.
(Example 10)
A raw material carbon fiber bundle (number of filaments: 24,000, strand strength: 6.3 GPa, elastic modulus: 294 GPa, fiber diameter: 5.4 μm) was subjected to oxidation treatment at 1,100° C. for 2 seconds in an air atmosphere. σ L was 10.2 GPa and σ L /σ S was 1.6. Adhesive strength with LM-PAEK resin was 78 MPa, and the number of fixation was 2.
(Example 11)
A raw material carbon fiber bundle (number of filaments: 12,000, strand strength: 4.0 GPa, elastic modulus: 230 GPa, fiber diameter: 6.9 μm) was subjected to oxidation treatment at 1,000° C. for 6 seconds in an air atmosphere. σ L was 7.6 GPa and σ L /σ S was 1.9. The adhesive strength with the LM-PAEK resin was 78 MPa, and the number of fixation was 3.
　（比較例１）
　表面酸化処理を行わなかった以外は実施例１と同様の炭素繊維束を用いた。サイジング剤付与による固着数は０であり、ＬＭ－ＰＡＥＫ樹脂との接着力は５１ＭＰａ発現した。Ｉ２６０ｎｍが０．００２と低く、ＬＭ－ＰＡＥＫ樹脂との接着力が低かったものと考えられる。 (Comparative example 1)
A carbon fiber bundle similar to that of Example 1 was used except that the surface oxidation treatment was not performed. The number of fixation due to application of the sizing agent was 0, and the adhesive strength with the LM-PAEK resin was 51 MPa. I 260 nm was as low as 0.002, and it is considered that the adhesive force with the LM-PAEK resin was low.
　（比較例２）
　加熱温度を５５０℃とし、処理時間を６０秒とした以外は実施例１と同様の方法で酸化処理を行った。ＬＭ－ＰＡＥＫ樹脂との接着力は６６ＭＰａ発現し、実施例１よりも低かった。 (Comparative example 2)
The oxidation treatment was performed in the same manner as in Example 1 except that the heating temperature was 550° C. and the treatment time was 60 seconds. The adhesive strength with LM-PAEK resin was 66 MPa, which was lower than that of Example 1.
　（比較例３）
　加熱温度を６００℃とし、処理時間を６秒とした以外は実施例１と同様の方法で酸化処理を行った。ＬＭ－ＰＡＥＫ樹脂との接着力は６１ＭＰａ発現し、加熱温度の高い実施例１よりも低かった。 (Comparative Example 3)
The oxidation treatment was performed in the same manner as in Example 1, except that the heating temperature was 600° C. and the treatment time was 6 seconds. The adhesive strength with the LM-PAEK resin was 61 MPa, which was lower than that of Example 1 in which the heating temperature was high.
　（比較例４）
　処理時間を３０秒とした以外は実施例３と同様の方法で酸化処理を行った。σＬおよびσＬ／σＳは処理時間の短い実施例３よりも低かった。 (Comparative Example 4)
The oxidation treatment was performed in the same manner as in Example 3, except that the treatment time was 30 seconds. σ L and σ L /σ S were lower than Example 3 with a shorter treatment time.
　（比較例５）
　炭素繊維前駆体用のポリマーの重合を、金属元素を含まないジメチルスルホキシド中で行い、金属含有量が３０ｐｐｍとなった原料炭素繊維束（フィラメント数１２，０００、ストランド強度４．９ＧＰａ、弾性率２３０ＧＰａ）を、重炭酸アンモニウムを電解質として、２５℃にて電解酸化を行った。流す電流と処理時間の積で与えられる電解処理量は１０Ｃ／ｇとした。Ｉ５５０ｎｍ／Ｉ８００ｎｍは１．９であり、実施例３よりも高く、サイジング剤付与後の固着数は７２と多かった。 (Comparative Example 5)
Polymerization of the polymer for the carbon fiber precursor was carried out in dimethyl sulfoxide containing no metal element, and a raw material carbon fiber bundle with a metal content of 30 ppm (number of filaments: 12,000, strand strength: 4.9 GPa, elastic modulus: 230 GPa ) was electrolytically oxidized at 25° C. using ammonium bicarbonate as an electrolyte. The amount of electrolytic treatment given by the product of the applied current and the treatment time was set to 10 C/g. I 550 nm /I 800 nm was 1.9, which was higher than in Example 3, and the number of fixations after application of the sizing agent was as high as 72.
　（比較例６）
　電解処理量を３０Ｃ／ｇとした以外は比較例５と同様の方法で処理を行った。Ｉ５５０ｎｍ／Ｉ８００ｎｍは２．９であり、実施例３よりも高く、サイジング剤付与後の固着数は９４と多かった。 (Comparative Example 6)
The treatment was carried out in the same manner as in Comparative Example 5 except that the amount of electrolytic treatment was changed to 30 C/g. I 550 nm /I 800 nm was 2.9, which is higher than that of Example 3, and the number of fixations after application of the sizing agent was as high as 94.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　本発明により提供される炭素繊維束は、航空機部材、自動車部材および船舶部材をはじめとして、ゴルフシャフトや釣竿等のスポーツ用途およびその他一般産業用途に好適に用いられる。 The carbon fiber bundles provided by the present invention are suitably used for sports applications such as golf shafts and fishing rods, as well as aircraft members, automobile members and ship members, and other general industrial applications.

Claims (4)

  1. 下記の（１）または（２）を満たす炭素繊維束。
    （１）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長２６０ｎｍでの吸光度（Ｉ２６０ｎｍ）が０．００５以上であり、波長５５０ｎｍの吸光度と波長８００ｎｍの吸光度との比である吸光度比（Ｉ５５０ｎｍ／Ｉ８００ｎｍ）が１．８以下であり、ループ強度σＬ（ＧＰａ）とストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）が１．７以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束。
    （２）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長５５０ｎｍでの吸光度（Ｉ５５０ｎｍ）が０．０１５以下であり、ループ強度σＬ（ＧＰａ）とストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）が１．７以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束。     A carbon fiber bundle satisfying the following (1) or (2).
    (1) Absorbance at a wavelength of 260 nm (I 260 nm ) is 0.005 or more, the absorbance ratio (I 550 nm /I 800 nm ), which is the ratio of the absorbance at a wavelength of 550 nm to the absorbance at a wavelength of 800 nm, is 1.8 or less, and the loop strength σ L (GPa) and the strand strength A carbon fiber bundle having a ratio (σ L /σ S ) to σ S (GPa) of 1.7 or more and an adhesive strength to LM-PAEK resin of 68 MPa or more as evaluated by a single fiber pull-out method.
    (2) Absorbance at a wavelength of 550 nm (I 550 nm ) is 0.015 or less, the ratio of the loop strength σ L (GPa) to the strand strength σ S (GPa) (σ L /σ S ) is 1.7 or more, and the LM evaluated by the single fiber pullout method - A carbon fiber bundle having an adhesive strength of 68 MPa or more with the PAEK resin.
  2. 下記の（１）～（３）の少なくとも一以上を満たす炭素繊維束。
    （１）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長２６０ｎｍでの吸光度（Ｉ２６０ｎｍ）が０．００５以上であり、波長５５０ｎｍの吸光度と波長８００ｎｍの吸光度との比である吸光度比（Ｉ５５０ｎｍ／Ｉ８００ｎｍ）が１．８以下であり、ループ強度σＬ（ＧＰａ）とストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）が１．７以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束。
    （２）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長５５０ｎｍでの吸光度（Ｉ５５０ｎｍ）が０．０１５以下であり、ループ強度σＬ（ＧＰａ）とストランド強度σＳ（ＧＰａ）との比（σＬ／σＳ）が１．７以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束。
    （３）炭素繊維束をジメチルスルホキシドに炭素繊維束の質量が７質量％になるように浸漬させ、２５℃で１０分間超音波処理を施して得られる抽出液の波長５５０ｎｍでの吸光度（Ｉ５５０ｎｍ）が０．０１５以下であり、ループ強度σＬ（ＧＰａ）が８．０ＧＰａ以上であり、単繊維プルアウト法で評価したＬＭ－ＰＡＥＫ樹脂との接着力が６８ＭＰａ以上である炭素繊維束。     A carbon fiber bundle that satisfies at least one of the following (1) to (3).
    (1) Absorbance at a wavelength of 260 nm (I 260 nm ) is 0.005 or more, the absorbance ratio (I 550 nm /I 800 nm ), which is the ratio of the absorbance at a wavelength of 550 nm to the absorbance at a wavelength of 800 nm, is 1.8 or less, and the loop strength σ L (GPa) and the strand strength A carbon fiber bundle having a ratio (σ L /σ S ) to σ S (GPa) of 1.7 or more and an adhesive strength to LM-PAEK resin of 68 MPa or more as evaluated by a single fiber pull-out method.
    (2) Absorbance at a wavelength of 550 nm (I 550 nm ) is 0.015 or less, the ratio of the loop strength σ L (GPa) to the strand strength σ S (GPa) (σ L /σ S ) is 1.7 or more, and the LM evaluated by the single fiber pullout method - A carbon fiber bundle having an adhesive strength of 68 MPa or more with the PAEK resin.
    (3) Absorbance at a wavelength of 550 nm (I 550 nm ) is 0.015 or less, the loop strength σ L (GPa) is 8.0 GPa or more, and the adhesive strength to LM-PAEK resin evaluated by the single fiber pull-out method is 68 MPa or more.
  3. ５５０℃の空気中で３時間加熱した際の質量減少率が５０％以下である請求項１または２に記載の炭素繊維束。 3. The carbon fiber bundle according to claim 1, which has a mass reduction rate of 50% or less when heated in air at 550° C. for 3 hours.
  4. 酸素含有雰囲気下において７００℃以上で０．１～６秒処理する炭素繊維束の製造方法。 A method for producing a carbon fiber bundle by treating at 700° C. or higher for 0.1 to 6 seconds in an oxygen-containing atmosphere.
PCT/JP2023/006919 2022-03-03 2023-02-27 Carbon fiber bundle and method for producing carbon fiber bundle WO2023167120A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5253092A (en) * 1975-10-28 1977-04-28 Nippon Carbon Co Ltd Surface treatment of carbon fiber
JPH01124679A (en) * 1987-11-04 1989-05-17 Asahi Chem Ind Co Ltd Oxidation treatment of carbonaceous fiber
US5292408A (en) * 1990-06-19 1994-03-08 Osaka Gas Company Limited Pitch-based high-modulus carbon fibers and method of producing same
JP2004238779A (en) * 2003-02-10 2004-08-26 Mitsubishi Rayon Co Ltd Method for producing carbon fiber
JP2010111990A (en) * 2008-10-06 2010-05-20 Oita Univ Expanded carbon fiber, method for producing the same, and solar cell

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5253092A (en) * 1975-10-28 1977-04-28 Nippon Carbon Co Ltd Surface treatment of carbon fiber
JPH01124679A (en) * 1987-11-04 1989-05-17 Asahi Chem Ind Co Ltd Oxidation treatment of carbonaceous fiber
US5292408A (en) * 1990-06-19 1994-03-08 Osaka Gas Company Limited Pitch-based high-modulus carbon fibers and method of producing same
JP2004238779A (en) * 2003-02-10 2004-08-26 Mitsubishi Rayon Co Ltd Method for producing carbon fiber
JP2010111990A (en) * 2008-10-06 2010-05-20 Oita Univ Expanded carbon fiber, method for producing the same, and solar cell

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