JP6543309B2 - Sizing agent-deposited carbon fiber bundle, method for producing the same, and method for producing pressure vessel using the sizing agent-deposited carbon fiber bundle - Google Patents

Description

  The present invention relates to a carbon fiber bundle to which a sizing agent is attached (hereinafter also referred to as "sizing agent-adhered carbon fiber bundle"), a method for producing the same, and a method for producing a CFRP pressure vessel using this sizing agent-adhered carbon fiber bundle.

  Composite materials composed of reinforcing fibers such as carbon fiber and aromatic polyamide fiber and matrix resin are widely used in general industries, automobiles, sports and leisure, aerospace, etc., utilizing their high specific strength and specific rigidity. Industrial applications of these composites being used are being further expanded in recent years. With the expansion of the use of composite materials, there is an increasing demand for a method of manufacturing composite materials that can make the physical properties of the composite appear high.

  Carbon fiber composite materials are being replaced by metallic materials as the cost is reduced because they have excellent mechanical properties. In particular, taking advantage of its light and strong characteristics, development of repair materials for concrete structures, blades for wind power generation, structural materials such as bodies and shafts of transport vehicles, various FRP pressure vessels, etc. Among these uses, CFRP pressure vessels using carbon fiber can be made smaller and lighter, and are widely developed as pressure vessels for fuel storage of automobiles using hydrogen and natural gas as fuel. .

  Such an FRP pressure vessel is mainly manufactured by a filament wind molding method (hereinafter, also referred to as "FW molding method") in which a fiber impregnated with a matrix resin is wound on the outer surface of a core liner. . The FW molding method is a molding method that has been widely adopted when manufacturing a pressure vessel using glass fiber, but is also adopted when manufacturing a pressure vessel using carbon fiber. However, a pressure vessel manufactured by FW molding using carbon fibers has a problem that the excellent fiber physical properties of carbon fibers are not sufficiently reflected.

  Patent Document 1 discloses a method of improving the resin impregnation property by reducing the fiber diameter of carbon fibers and forming wrinkles on the surface of the fibers. However, even if the fiber diameter of the carbon fiber is reduced, the resin impregnation can not be sufficiently improved.

  Patent Document 2 discloses a carbon fiber bundle for FW formation having high tensile strength. In the FW forming method, high tension is applied to the carbon fiber bundle to impregnate the resin. Therefore, the carbon fiber bundle is likely to be fluffed or broken due to abrasion with a fixing guide, a roller or the like in the process. The fuzzing and breakage of the carbon fiber bundle not only deteriorate the processability and stability but also adversely affect the performance of the final formed pressure vessel. That is, the physical properties of the carbon fiber bundle having high tensile strength can not be sufficiently reflected in the performance of the composite material. Therefore, abrasion resistance and yarn breakage resistance are required for carbon fibers used in the FW forming method.

  It has been widely practiced to apply a sizing agent to a carbon fiber bundle in order to improve the abrasion resistance and the yarn breakage resistance. For example, Patent Document 3 discloses a method for applying a sizing agent in which a sizing agent applying step and a drying step are alternately repeated. However, in the method disclosed in Patent Document 3, a large amount of sizing agent adheres to the outer layer portion of the carbon fiber bundle, and the amount of the sizing agent attached to the inner layer portion of the carbon fiber bundle is reduced. Therefore, the carbon fiber bundle is likely to be prevented from impregnating the resin by the sizing agent present in the outer layer portion of the carbon fiber bundle. As a result, the performance of the obtained composite material does not fully reflect the physical properties of the carbon fiber bundle.

JP 2002-69754 A Patent 3047731 gazette JP, 2009-242964, A

  An object of the present invention is to provide a sizing agent-adhered carbon fiber bundle particularly suitable for FW forming, having high resin impregnation while maintaining high abrasion resistance and yarn breakage resistance, and a method for producing the same. . Another object of the present invention is to provide a method for producing a CFRP pressure vessel by FW forming method using the sizing agent-adhered carbon fiber bundle.

  As a result of intensive investigations on the above problems, the present inventors attached a sufficient amount of sizing agent to the inner layer portion of the carbon fiber bundle for FW forming to which the sizing agent is attached, and attached amount of sizing agent on the outer layer portion It has been found that the resin impregnation can be made high while keeping the abrasion resistance and the yarn breakage resistance high by suppressing the above. And, after immersing a carbon fiber bundle in a sizing bath, such a sizing agent-adhered carbon fiber bundle is sprayed with a gas onto the carbon fiber bundle to remove a part of the sizing agent adhering to the carbon fiber bundle. They have found that they can be manufactured and have completed the present invention.

  The present invention which solves the above-mentioned subject is described below.

[1] The sizing agent luminescence count number (S) of the outer layer portion of the carbon fiber bundle, wherein the sizing agent is adhered to 0.8 to 3.0% by mass of the carbon fiber bundle, and measured by the cathode luminescence method; The sizing agent luminescence count number (I) of the inner layer portion of the carbon fiber bundle measured by the luminescence method is the following formula (1)
0.8 <I / S <2.0 (1)
A sizing agent-adhered carbon fiber bundle for filament winding molding, which satisfies the following relationship:

  [2] A carbon fiber bundle is immersed in a sizing bath containing a sizing agent to adhere the sizing agent to the carbon fibers, and then a gas is blown to remove a part of the sizing agent adhering to the carbon fiber bundle A method for producing a sizing agent-adhered carbon fiber bundle for filament winding molding according to [1], characterized in that

  [3] The method for producing a sizing agent-adhered carbon fiber bundle for filament winding molding according to [2], wherein the critical tension of the carbon fiber bundle is 65 to 95 mN / m.

  [4] The method for producing a sizing agent-adhered carbon fiber bundle for filament winding molding according to [2], wherein the carbon fiber bundle is immersed in the sizing bath 2 to 10 times.

[5] After immersing the carbon fiber bundle in a sizing bath containing a sizing agent to attach the sizing agent to the carbon fiber, a gas is blown to remove a part of the sizing agent adhering to the carbon fiber bundle By
The sizing agent luminescence count number (S) of the outer layer portion of the carbon fiber bundle, wherein the sizing agent is adhered to 0.8 to 3.0% by mass of the carbon fiber bundle, and measured by a cathode luminescence method, and a cathode The sizing agent luminescence count number (I) of the inner layer portion of the carbon fiber bundle measured by the luminescence method is the following formula (1)
0.8 <I / S <2.0 (1)
Obtaining a sizing agent-adhered carbon fiber bundle satisfying the following relationship;
A step of impregnating the sizing agent-adhered carbon fiber bundle with a resin to obtain a resin-impregnated carbon fiber bundle;
Winding the resin-impregnated carbon fiber bundle on the outer surface of a liner having a hollow portion;
Curing the resin impregnated in the resin impregnated carbon fiber bundle;
A manufacturing method of a pressure vessel characterized by having.

  [6] The method for producing a pressure vessel according to [5], wherein the critical tension of the carbon fiber bundle is 65 to 95 mN / m.

  [7] The method for producing a pressure vessel according to [5] or [6], wherein the carbon fiber bundle is immersed in the sizing bath 2 to 10 times.

  The sizing agent-adhered carbon fiber bundle of the present invention is high in resin impregnation property and high in abrasion resistance and yarn breakage resistance. Therefore, this sizing agent-adhered carbon fiber bundle is particularly suitable for FW forming. Then, the performance of the CFRP pressure vessel manufactured by the FW forming method using the sizing agent-adhered carbon fiber bundle fully reflects the fiber physical properties of the carbon fiber.

  According to the method for producing a sizing agent-adhered carbon fiber bundle of the present invention, it is possible to easily obtain a sizing agent-adhered carbon fiber bundle having high resin impregnation property and high abrasion resistance and yarn breakage resistance.

  Hereinafter, a sizing agent-adhered carbon fiber bundle of the present invention, a method for producing the same, and a method for producing a pressure vessel by FW forming method will be described.

(1) Sizing agent-adhered carbon fiber bundle The sizing agent-adhered carbon fiber bundle of the present invention has a sizing agent luminescence count number (S) measured by the cathode luminescence method in the outer layer portion thereof and a cathode luminescence method in the inner layer portion (hereinafter Sizing agent luminescence count number (I) measured by "CL method") and the following formula (1)
0.8 <I / S <2.0 (1)
It is characterized by satisfying the relationship of Hereinafter, I / S is also referred to as sizing agent emission intensity ratio.

Here, the sizing agent luminescence count number measured by the CL method will be described. The CL method is a measurement method for detecting the light emission in the ultraviolet, visible, and near infrared regions emitted when the sample is irradiated with an electron beam. In the polymer compound, a molecule having a conjugated double bond shows light emission, and the integrated value of the light emission amount is proportional to the amount of the sizing agent molecule which emits light. Therefore, the adhesion amount ratio of the sizing agent in the inner layer portion and the outer layer portion of the sizing agent-adhered carbon fiber bundle is measured by comparing the integrated value of the light emission amount in the inner layer portion and the outer layer portion of the sizing agent-adhered carbon fiber bundle. be able to. The sizing agent emission count number (I) of the inner layer portion of the sizing agent-adhered carbon fiber bundle measured by the CL method means that the sizing agent-adhered carbon fiber bundle is divided into two equal parts along its axis. refers to the number of emission counts measured in the cross-sectional surface, sizing agents emission count of the outer layer portion and the (S) refers to the number of emission counts to be measured in a non-cross section of the cut divided by the carbon fiber bundle.

  The presence of a sufficient amount of the sizing agent in the inner layer portion of the carbon fiber bundle can provide an entropy sufficient to sufficiently impregnate the resin to the inner portion of the carbon fiber bundle. When I / S is 2.0 or more, the sizing agent in the inner layer portion is excessive, and the binding effect of restraining filaments is strengthened. As a result, when impregnating the resin, the sizing agent-adhered carbon fiber bundle is not sufficiently opened, and the impregnation of the resin becomes insufficient.

  Since the sizing agent-adhered carbon fiber bundle of the present invention keeps high the abrasion resistance and the thread breakage resistance imparted by the sizing agent, the sizing agent-adhered carbon fiber bundle is damaged by abrasion with a fixing guide, a roller or the like in the FW forming process. hard. Further, since the sizing agent-adhered carbon fiber bundle removes a part of the sizing agent adhering to the outer layer portion, it is easy to impregnate the resin from the outer layer portion toward the inner layer portion. Therefore, it is hard to produce impregnation leak of resin. As a result, in the carbon fiber composite material produced using the sizing agent-adhered carbon fiber bundle of the present invention, the fiber physical properties inherent to carbon fibers are sufficiently reflected, and the performance becomes high.

  Such a carbon fiber bundle can be manufactured by the following method.

(2) Method for producing sizing agent-adhered carbon fiber bundle The method for producing a sizing agent-adhered carbon fiber bundle of the present invention is
Immersing a carbon fiber bundle consisting of a plurality of carbon fiber filaments in a sizing bath;
Removing a portion of the sizing agent adhering to the carbon fiber bundle by blowing a gas onto the carbon fiber bundle withdrawn from the sizing bath;
To have The sizing agent-adhered carbon fiber bundle produced through the above steps has a sizing agent luminescence count number (S) measured by the cathode luminescence method in the outer layer portion and a sizing agent luminescence count measured by the cathode luminescence method in the inner layer portion The number (I) and the following equation (1)
0.8 <I / S <2.0 (1)
It is characterized by satisfying the relationship of

<Carbon fiber>
Although the carbon fiber used by this invention is not specifically limited, Carbon fibers, such as a pitch type | system | group, rayon type | system | group, a polyacryl nitrile (PAN) type | system | group, can be used. In order to improve operability, processability, and mechanical strength, PAN-based carbon fibers are preferred. Moreover, as for the filament number of a carbon fiber bundle, 1000-50000 filaments are preferable, and 3000-30000 filaments are especially preferable. 4-15 micrometers is preferable and, as for the diameter of a single fiber filament, 5-11 micrometers is especially preferable. Strand tensile strength is preferably ^{400~600kgf / mm 2, 450~550kgf / mm} 2 is particularly preferred. Modulus, preferably ^{20~35kgf / mm 2, 24~30kgf / mm} 2 is particularly preferred.

  Although such a carbon fiber may use a commercial item, it can also be manufactured by spinning precursor fiber by the following method, and making it flameproof and carbonize it.

(Precursor fiber)
As a precursor fiber used for manufacture of carbon fiber, PAN type fiber is used preferably. Specifically, a spinning stock solution containing 90% by mass or more, preferably 95% by mass or more of acrylonitrile and containing 10% by mass or less of other monomers is spun from a spinneret as a spinning solution prepared by homopolymerization or copolymerization. It is preferable to use PAN-based raw material fibers produced by Other monomers include itaconic acid, fumaric acid and (meth) acrylic acid esters.

  As a spinning method, any of wet, dry-wet, and dry spinning methods can be used, but since carbon fibers finally obtained form wrinkles on the surface and adhesion to a resin can be expected, wet methods can be used. The spinning method is preferred. In addition, as a spinning solution, what melt | dissolved the said acrylic polymer in a 30-60 mass% zinc chloride solution is preferable.

  If necessary, spinning may be performed using a spinneret (for example, a turtle shell type) for the spinning nozzle. In addition, the spinning solution may be filtered to remove impurities in the spinning solution. The filtration of the stock spinning solution greatly contributes to the process stabilization and the improvement of strength, elastic modulus and the like. Therefore, it is particularly effective in the case where improvement in process stability, strength and elastic modulus, etc. is required rather than making the fiber surface of the resulting carbon fiber porous.

  The crude raw fiber is subjected to washing treatment and wet heat drawing treatment while applying tension, but it is preferable that the total draw ratio in the washing step and the wet heat drawing step be 10 to 15 times.

(Flameproof treatment)
The precursor fiber thus obtained is subsequently heat-treated at 220 to 300 ° C., preferably 230 to 260 ° C. in heated air to obtain a flameproofed fiber. The treatment at this time is generally carried out at a draw ratio of 0.85 to 1.30, but in order to obtain a carbon fiber of high strength and high modulus, a draw ratio of 0.95 to 1.1. 30 is more preferred.

(Carbonization treatment)
The flameproofed fibers are carbonized by conventional known methods. For example, the temperature is raised under an inert gas atmosphere such as nitrogen or argon, preferably under an inert gas atmosphere having an oxygen concentration of less than 0.05 volume ppm, and the temperature is gradually raised in the carbonization furnace. Baking with controlled tension. 600-2000 degreeC is preferable and, as for a calcination temperature, 1000-1700 degreeC is especially preferable. Inert gases are preferred because nitrogen is inexpensive.

  The carbon fiber bundle used in the present production method preferably has a critical tension of 65 to 95 mN / m, particularly preferably 70 to 90 mN / m. In this range of critical tension carbon fiber bundles, the inner layer portion can be impregnated with a sufficient amount of sizing agent. When the critical tension of the carbon fiber bundle is less than 65 mN / m, the carbon fiber bundle is not provided with a sufficient amount of sizing agent because the wettability with the sizing agent is lowered. As a result, the affinity between the carbon fiber bundle and the matrix resin may be lowered, and the inherent fiber physical properties of the carbon fiber may not be sufficiently reflected in the performance of the carbon fiber composite material. In addition, when the critical tension exceeds 95 mN / m, although the wettability with the sizing agent becomes high, a structurally weak oxide layer called a fragile layer is formed on the surface of the carbon fiber. As a result, the performance of the resulting carbon fiber composite material may be degraded.

  In order to make the critical tension of the carbon fiber bundle in the above range, it is preferable to carry out surface treatment after carbonization treatment in the production process of carbon fiber. Although the method of surface treatment is not particularly limited, it is possible to use liquid phase oxidation using a chemical solution, electrolytic oxidation in which electrolytic treatment is performed using carbon fibers as an anode in an electrolytic solution, or gas phase oxidation in which plasma treatment is performed in a gas phase. . Among these, from the viewpoint of productivity, uniformity of processing, and safety, electrolytic oxidation is preferably used. The electrolyte of the electrolytic solution used in the electrolytic treatment is not particularly limited, but inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, boric acid and carbonic acid; organic acids such as acetic acid, butyric acid, oxalic acid, acrylic acid and maleic acid; Ammonium hydrogen sulfate, ammonium nitrate, ammonium hydrogen nitrate, ammonium dihydrogen phosphate, ammonium dihydrogen phosphate, ammonium carbonate such as ammonium carbonate or ammonium hydrogen carbonate, or ammonia salt; alkalis such as sodium hydroxide, potassium hydroxide, barium hydroxide Hydroxide; inorganic salts such as sodium carbonate, sodium hydrogencarbonate, sodium phosphate and potassium phosphate; Organic salts such as sodium maleate, sodium acetate, potassium acetate and sodium benzoate; alone or as a mixture of two or more It can be used.

  0-100 degreeC is preferable and, as for the temperature of electrolyte solution, 25-45 degreeC is especially preferable. Moreover, 5-25 mass% is preferable, and, as for the density | concentration of electrolyte, 8-12 mass% is especially preferable. The electrolytic treatment is preferably performed using a plurality of electrolytic cells. It is preferable to use 2 to 10 tanks in consideration of equipment, cost, and complexity of setting conditions. The amount of electricity is preferably 0.5 coulomb or more per 1 g of carbon fiber, and particularly preferably 2 to 100 coulomb.

  In carrying out the above-mentioned electrolytic treatment, it is preferable to pre-impregnate the carbon fiber bundle with an electrolytic solution used in the electrolytic treatment before the electrolytic treatment. This pre-impregnation may be performed by any method as long as the electrolyte can be impregnated into the inner layer portion of the carbon fiber bundle. However, since the carbon fiber has high surface hydrophobicity, the inner layer portion of the carbon fiber bundle may not be sufficiently impregnated with the electrolytic solution simply by passing the carbon fiber bundle through the electrolytic cell simply filled with the electrolytic solution. Therefore, when passing the carbon fiber bundle through the electrolytic cell, it is preferable to make the electrolytic solution in the electrolytic cell turbulent. As a method of generating turbulent flow, use of a shower and a vibrator can be mentioned.

<Sizing agent application process>
The sizing agent used in the present invention is preferably selected according to the matrix resin used for the composite material. For example, an epoxy resin, an epoxy-modified polyurethane resin, a polyester resin, a phenol resin, a polyamide resin, a polyurethane resin, a polyimide resin, a polyvinyl alcohol resin, a polyvinyl pyrrolidone resin, a polyether sulfone resin, etc. are used alone or in combination of two or more be able to.

  The above resin is used as an organic solvent solution or as an aqueous dispersion. In consideration of safety, environment, etc., it is preferable to use as a water dispersion.

  As a method for applying the sizing agent to the carbon fiber bundle, although a continuous system and a batch system can be mentioned, it is preferable to carry out the continuous system with high productivity.

  In the production method of the present invention, the carbon fiber bundle is immersed in the sizing bath preferably a plurality of times, more preferably 2 to 10 times, particularly preferably 3 to 5 times. In one immersion, the inner layer portion of the carbon fiber bundle is not impregnated with a sufficient amount of sizing agent, and the carbon fibers in the inner layer portion are not sufficiently coated with the sizing agent. As a result, the abrasion resistance of the carbon fiber bundle and the affinity to the matrix resin become insufficient. Moreover, immersion more than 10 times increases the number of processes and reduces productivity. The sizing agents contained in each sizing bath may be identical or different, but are preferably identical.

  The immersion time in the sizing bath is not particularly limited, but it is preferable that the immersion time be 5 seconds or less because the increase in the immersion time is synonymous with the increase in the process.

  In the production method of the present invention, each immersion of the carbon fiber bundle in the sizing bath is performed continuously, and there is no drying step between the immersion steps. When a drying step is present between the respective immersion steps, the sizing agent is first attached to the outer layer portion of the carbon fiber bundle, and the drying step in the drying step prevents the impregnation of the sizing agent into the inner layer portion. As a result, in the finally obtained carbon fiber composite material, the inner layer portion of the carbon fiber bundle is not sufficiently impregnated with the matrix resin, and the performance of the carbon fiber composite material becomes insufficient. In addition, since the spraying time of the gas mentioned later is a very short time of 1 second or less, it does not correspond to said drying process in this invention.

  The concentration and temperature of the sizing agent, the tension of the carbon fiber bundle at the time of immersion, and the like are appropriately adjusted so that the adhesion amount of the sizing agent falls within the appropriate range.

<Sizing agent removal process>
The carbon fiber bundle to which the sizing agent is attached is partially removed from the sizing agent. The removal of the sizing agent is performed by blowing a gas toward the carbon fiber bundle while continuously running the carbon fiber bundle to which the sizing agent is attached. More specifically, the carbon fiber bundle is brought into contact with the circumferential surface of the flat roller, and the gas is blown toward the carbon fiber bundle in contact with the circumferential surface of the flat roller. Thereby, a part of the sizing agent adhering to the outer layer side of the carbon fiber bundle is removed. As a result, it is possible to obtain a sizing agent-adhered carbon fiber bundle in which the inner layer portion of the carbon fiber bundle contains a sufficient amount of sizing agent and the sizing agent adhesion amount in the outer layer portion is reduced.

The sizing agent emission count number (S) of the outer layer portion of the sizing agent-adhered carbon fiber bundle and the sizing agent emission count number (I) of the inner layer portion, which are measured by a cathode luminescence method (hereinafter also referred to as "CL method") Is the following equation (1)
0.8 <I / S <2.0 formula (1)
Satisfies the following relationship (Eq. 2)
0.9 <I / S <1.8 formula (2)
It is preferable to satisfy the following equation (3)
1.0 <I / S <1.6 ... Formula (3)
It is particularly preferred to satisfy the following relationship:

  The velocity of the blown gas is preferably 15 to 50 m / sec at the surface of the carbon fiber bundle. When the wind speed is 15 m / sec or more, the excess sizing agent in the outer portion of the carbon fiber bundle can be sufficiently removed. As a result, the carbon fiber bundle improves the permeability of the resin to the inner layer portion in the resin impregnation step. When the wind speed exceeds 50 m / sec, the carbon fiber strand is disturbed, and there is a tendency that fuzzing and winding on a flat roller tend to occur.

  The gas spraying time is preferably 0.01 to 1 second, and particularly preferably 0.05 to 0.5 second.

  The adhesion amount of the sizing agent in the sizing agent-adhered carbon fiber bundle after removal of the excess sizing agent is 0.8 to 3.0 mass%, and 1.0 to 2.0 mass%. preferable. When the adhesion amount of the sizing agent is less than 0.8% by mass, the sizing agent may not sufficiently cover the carbon fibers. As a result, the abrasion resistance of the carbon fiber bundle is reduced, and the generation of fluff tends to be remarkable during the composite material forming process. Moreover, when the adhesion amount of a sizing agent exceeds 3.0 mass%, the binder effect of a sizing agent may be too strong, and the permeability of resin in a carbon fiber bundle may fall. As a result, the fiber physical properties of the carbon fiber bundle tend to be less likely to be reflected in the performance of the finally obtained carbon fiber composite material.

  In order to fully reflect the fiber physical properties of the carbon fiber bundle in the performance of the carbon fiber composite material, it is necessary to sufficiently impregnate the matrix resin in the inner layer portion of the carbon fiber bundle and not to generate fibers that do not contribute to the performance of the composite material. is there. For that purpose, entropy sufficient for the matrix resin to be impregnated in the inner layer portion of the carbon fiber bundle is essential. The sizing agent has higher affinity to the matrix resin than carbon fiber. Therefore, a sufficient amount of sizing agent adheres to the inner layer of the carbon fiber bundle, and the sizing agent attached to the outer layer of the carbon fiber bundle is reduced, so that the matrix resin is sufficiently extended to the inner layer of the carbon fiber bundle. Can be called to As a result, the fiber physical properties of the carbon fiber bundle can be sufficiently reflected in the performance of the final carbon fiber composite material.

(3) Manufacturing Method of Pressure Vessel by FW Forming Method In the present invention, the pressure vessel made of CFRP is manufactured by the FW forming method using the sizing agent-adhered carbon fiber bundle of the present invention. That is, the carbon fiber bundle is wound around a liner or the like while being impregnated with a resin, and then the resin is cured. This FW forming method is likely to cause damage to the carbon fiber bundle due to abrasion with a roller or a guide during the process. When the carbon fiber bundle is damaged, not only process passability and process stability are degraded, but also the performance of the resulting carbon fiber composite material is degraded.

  The sizing agent-adhered carbon fiber bundle is impregnated with a sufficient amount of sizing agent. Therefore, even if abrasion with a roller or a guide occurs, it is hard for the sizing agent-adhered carbon fiber bundle to be fluffed or broken. In addition, the sizing agent-adhered carbon fiber bundle has a small amount of sizing agent adhering to the outer layer portion. Therefore, this sizing agent does not become an obstacle when impregnating the resin.

  In the present invention, the CFRP pressure vessel is manufactured by the FW forming method using the sizing agent-adhered carbon fiber bundle. In the present invention, a sizing agent-adhered carbon fiber bundle manufactured in advance may be used, or the manufacturing of the sizing agent-adhered carbon fiber bundle and the manufacture of a CFRP pressure vessel by FW forming method are continuously performed. Also good.

  The resin is preferably impregnated while opening the sizing agent-adhered carbon fiber bundle using an opening roller or the like.

  As resin (matrix resin), a thermosetting resin is preferable. For example, epoxy resin, unsaturated polyester resin, vinyl ester resin and phenol resin can be used. Further, additives such as a curing agent and a defoaming agent may be added to the resin. The curing temperature, the effect time and the like are conventionally known, and are appropriately adjusted according to the resin used.

  In the method for producing a CFRP pressure vessel according to the present invention, a sizing agent-adhered carbon fiber bundle (hereinafter also referred to as “resin-impregnated carbon fiber bundle”) impregnated with resin on the outer surface of a liner having a hollow portion is the shaft of the liner. A fiber-reinforced resin layer (A) and / or a fiber-reinforced resin layer (B) in which resin-impregnated carbon fiber bundles are helically arranged with respect to the axial direction of the liner are laminated. In addition, the laminated structure of a fiber reinforced resin layer (A) and / or a fiber reinforced resin layer (B) is suitably determined according to the performance of a desired pressure vessel.

  Thereafter, the resin impregnated in the resin-impregnated carbon fiber bundle is cured by a curing method according to the resin to produce a CFRP pressure vessel.

  The CFRP pressure vessel manufactured in this manner sufficiently reflects the excellent fiber physical properties of the carbon fiber bundle. The actual breaking pressure with respect to the theoretical breaking pressure of the CFRP pressure vessel produced by the present production method is preferably 85% or more, more preferably 90% or more, and particularly preferably 95% or more.

  Hereinafter, the present invention will be more specifically described by way of examples, but the present invention is not limited thereto. In addition, the evaluation method in an Example is as follows.

[Measurement of luminescence count of sizing agent measured by CL method]
For measurement of the luminescence count of the sizing agent by the CL method, Topcon color fluorescence electron microscope was used. The sizing agent-adhered carbon fiber bundle was fixed on a carbon tape to prepare a measurement sample. The measurement conditions were an acceleration voltage of 5 kV, an aperture diameter of 50 μm, a current mode LCT-S, a pixel size of 3, a spectroscope slit open, and a magnification of 1000, and integrated luminescence was measured at 280 ± 10 nm for 3 minutes by grating spectroscopy.

[Method for evaluating pressure vessel rupture strength]
Back tension 4 kg / bundle, winding speed 0.5 m / while impregnating resin consisting of sizing agent attached carbon fiber bundle into resin shape consisting of the following resin composition in cylinder shape aluminum liner of length 504 mm, outer diameter 160 mm, thickness 2 mm After winding the hoop layer one layer at a pitch of 1.6 cm at a speed of sec, one helical layer was laminated. Then, it was made to harden | cure in a 120 degreeC curing furnace for 11 hours, and the pressure container for fracture strength evaluation was obtained.
Resin composition:
Bisphenol A type epoxy resin ··· 100 parts by weight 4-methylcyclohexane-1,2-dicarboxylic acid anhydride ··· 80 parts by weight As the bisphenol A type epoxy resin, EPON 828 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.) )It was used. As 4-methylcyclohexane-1,2-dicarboxylic acid anhydride, LINDAU CHEMICAL INC. Made of Lindride 52 (trade name).

The pressure vessel for evaluation of breaking strength was subjected to water pressure at 45 MPa / sec using a burst tester to measure the actual breaking pressure (P ₁ ). This measurement was carried out three times for each example and comparative example, and the average value was determined respectively.

[Calculation of tank fracture strength occurrence rate]
The theoretical burst pressure (P ₀ ) of the pressure vessel was calculated by finite element analysis using Algor FEA software. From the theoretical breaking pressure (P ₀ ) and the actual breaking pressure (P ₁ ), the following equation (3)
Tank breaking strength occurrence rate (%) = P ₁ / P ₀ × 100 ... Formula (3)
The tank fracture strength occurrence rate was calculated by.

[Measurement method of critical tension]
The critical tension of the carbon fiber bundle was determined by capillary infiltration. As a test solution, the liquid described in JIS K 6768, water (73.0 mN / m), methanol (22.6 mN / m), formamide (58.0 mN / m), ethylene glycol monoethyl ether (30.0 mN / m) )It was used.

[Measurement of adhesion amount of sizing agent]
About 5 g of chops of the sizing agent-adhered carbon fiber bundle were collected, and the mass (W1) was measured. After measuring the mass (W2) of the crucible which had been made constant beforehand, the chop was placed in the crucible and heat treated for 30 minutes in a hot air circulating dryer at 450 ± 5 ° C. under a nitrogen atmosphere. After cooling to room temperature in a desiccator, the mass (W3) of the crucible containing the carbon fiber chops was measured. Formula (4)
Sizing agent adhesion amount (%) = (W1 + W2-W3) / (W3-W2) * 100 .. Formula (4)
The sizing agent adhesion amount was calculated by

[Resin impregnated strand strength of carbon fiber]
The resin-impregnated strand strength of the sizing agent-adhered carbon fiber bundle was measured by the method defined in JIS.R. 7608.

[Method of measuring fuzz]
The sizing agent-adhered carbon fiber bundle was allowed to travel between urethane sheets carrying a 125 g weight for 2 minutes at a speed of 50 feet / minute, and the amount of carbon fibers accumulated in the urethane sheet was measured.

[Measurement method of MPF]
The sizing agent-adhered carbon fiber bundle is run at a speed of 50 feet / minute for 2 minutes between five pin guides under a tension of 200 g, and then passed between urethane sheets carrying a 125 g weight; The amount of carbon fibers accumulated in the urethane foam was measured.

Example 1
A copolymer spinning stock solution consisting of 95% by mass of acrylonitrile / 4% by mass of methyl acrylate / 1% by mass of itaconic acid is wet-spun by an ordinary method, and after washing with water, oiling and drying, the total draw ratio becomes 14 times. Steam drawing was performed to obtain a precursor fiber of 24,000 filaments having a denier of 0.65 denier. While drawing the obtained precursor fiber in heated air, a flameproofing treatment is performed in a temperature range of 240 to 250 ° C, and then a carbonization treatment is performed in a nitrogen atmosphere at a temperature range of 300 to 1200 ° C, An unelectrolyzed carbon fiber bundle was obtained. The unelectrolyzed carbon fiber bundle is impregnated with an overflow bath in which the water surface of the electrolyte solution is made turbulent by using a 10% by mass aqueous solution of ammonium sulfate as an electrolyte solution, and then an electric condition of 50 coulombs / g of total electricity Electrolytic oxidation treatment. The critical tension of the electrolytically oxidized carbon fiber bundle was 76 mN / m.

The carbon fiber bundle was immersed in a sizing bath (concentration 33 g / l) containing epoxy-modified urethane as a main ingredient by dipping three times. After the second and third immersions, the carbon fiber bundles traveling on the roller surface were blown with compressed air using a blower (air velocity: 2.8 m / 0.1 sec). After passing through the drying process, it is wound on a bobbin using a winder to obtain a sizing agent-adhered carbon fiber bundle having a density of 1.79 g / cm ³ , a strand strength of 4700 MPa and a sizing agent luminous intensity ratio (I / S) of 1.5. The The sizing agent adhesion amount, sizing agent luminescence intensity ratio (I / S), fuzz, and MPF of the obtained sizing agent-adhered carbon fiber bundle are shown in Table 1.

  Using this sizing agent-adhered carbon fiber bundle, a pressure vessel for fracture strength evaluation was manufactured according to the aforementioned evaluation method for pressure vessel fracture strength. When an internal pressure test was conducted on the obtained pressure container for evaluation of breaking strength, the breaking strength was 52 MPa, and the tank breaking strength development rate was a very high value of 101.7%.

Example 2
The carbon fiber bundle after electrolytic oxidation treatment obtained in Example 1 was dipped three times in a sizing bath (concentration 33 g / l) containing unsaturated polyester as a main ingredient by dip method. After the third immersion, compressed air was blown to the carbon fiber bundle traveling on the roller surface using a blower (wind velocity: 2.1 m / 0.1 sec). After passing through the drying process, it is wound on a bobbin using a winder to obtain a sizing agent-adhered carbon fiber bundle having a density of 1.79 g / cm ³ , a strand strength of 4600 MPa, and a sizing agent luminous intensity ratio (I / S) of 1.0. The The sizing agent adhesion amount, sizing agent luminescence intensity ratio (I / S), fuzz, and MPF of the obtained sizing agent-adhered carbon fiber bundle are shown in Table 1.

  Using this sizing agent-adhered carbon fiber bundle, a pressure vessel for fracture strength evaluation was manufactured according to the aforementioned evaluation method for pressure vessel fracture strength. When an internal pressure test was conducted on the obtained pressure container for evaluation of breaking strength, the breaking strength was 48 MPa and the tank breaking strength development rate was a very high value of 95.7%.

[Example 3]
Using the carbon fiber precursor fiber obtained in Example 1, while subjecting the obtained precursor fiber to stretching in heated air, a flameproofing treatment is performed in a temperature range of 240 to 250 ° C., and then in a nitrogen atmosphere, 300 Carbonization treatment was performed within a temperature range of -1300 ° C. to obtain unelectrolyzed carbon fibers.

  The unelectrolyzed carbon fiber bundle is impregnated with an overflow bath in which the water surface of the electrolyte solution is made turbulent by using a 10% by mass aqueous solution of ammonium sulfate as an electrolyte solution, and then the electric condition of 60 coulombs / g of total electricity Electrolytic oxidation treatment. The critical tension of the electrolytically oxidized carbon fiber bundle was 78 mN / m.

The carbon fiber bundle after electrolytic oxidation treatment was immersed in a sizing bath (concentration 33 g / l) containing epoxy modified urethane as a main ingredient by dip method three times. After the third immersion, compressed air was blown to the carbon fiber bundle traveling on the roller surface using a blower (wind velocity 2.5 m / 0.1 sec). After passing through the drying process, it is wound on a bobbin using a winder to obtain a sizing agent-adhered carbon fiber bundle having a density of 1.81 g / cm ³ , a strand strength of 4600 MPa, and a sizing agent luminous intensity ratio (I / S) of 0.9. The The sizing agent adhesion amount, sizing agent luminescence intensity ratio (I / S), fuzz, and MPF of the obtained sizing agent-adhered carbon fiber bundle are shown in Table 1.

  Using this sizing agent-adhered carbon fiber bundle, a pressure vessel for fracture strength evaluation was manufactured according to the aforementioned evaluation method for pressure vessel fracture strength. When an internal pressure test was performed on the obtained pressure container for evaluating breaking strength, the breaking strength was 43 MPa, and the tank breaking strength occurrence rate was a very high value of 92.3%.

Example 4
The carbon fiber bundle after electrolytic oxidation treatment obtained in Example 3 was dipped three times in a sizing bath (concentration 32 g / l) containing unsaturated polyester as a main ingredient by dip method. After the second and third immersions, the carbon fiber bundles traveling on the roller surface were blown with compressed air using a blower (air velocity: 2.8 m / 0.1 sec). After passing through the drying process, it was wound on a bobbin using a winder to obtain sizing agent-adhered carbon fiber having a density of 1.81 g / cm ³ , a strand strength of 4600 MPa, and a sizing agent luminous intensity ratio (I / S) of 1.2. . The sizing agent adhesion amount, sizing agent luminescence intensity ratio (I / S), fuzz, and MPF of the obtained sizing agent-adhered carbon fiber bundle are shown in Table 1.

  Using this sizing agent-adhered carbon fiber bundle, a pressure vessel for fracture strength evaluation was manufactured according to the aforementioned evaluation method for pressure vessel fracture strength. When an internal pressure test was conducted on the obtained pressure container for evaluation of breaking strength, the breaking strength was 45 MPa, and the tank breaking strength development rate was a very high value of 99.4%.

[Example 5]
In the carbon fiber bundle before electrolytic oxidation treatment obtained in Example 1, without impregnating the carbon fiber bundle with an electrolytic solution, an aqueous solution of 8% by mass of ammonium sulfate is used as an electrolyte aqueous solution as an electrolyte solution, and the total amount of electricity is 30 coulomb / g The electrolytic oxidation treatment was performed under the following electric conditions. The critical tension of the electrolytically oxidized carbon fiber bundle was 75 mN / m.

The carbon fiber bundle after the electrolytic oxidation treatment was dipped once in a sizing bath (concentration 34 g / l) containing an epoxy-modified urethane as a main ingredient by dipping. Compressed air was blown onto the carbon fiber bundle traveling on the roller surface using a blower (wind velocity: 2.8 m / 0.1 sec). After passing through the drying process, it was wound on a bobbin using a winder to obtain sizing agent-adhered carbon fiber having a density of 1.79 g / cm ³ , a strand strength of 4400 MPa, and a sizing agent luminous intensity ratio (I / S) of 0.8. . The sizing agent adhesion amount, sizing agent luminescence intensity ratio (I / S), fuzz, and MPF of the obtained sizing agent-adhered carbon fiber bundle are shown in Table 1.

  Using this sizing agent-adhered carbon fiber bundle, a pressure vessel for fracture strength evaluation was manufactured according to the aforementioned evaluation method for pressure vessel fracture strength. When an internal pressure test was conducted on the obtained pressure container for evaluation of breaking strength, the breaking strength was 47 MPa and the tank breaking strength occurrence rate was 88.2%.

Comparative Example 1
The carbon fiber bundle obtained in Example 1 was impregnated with an electrolytic solution in the same manner as in Example 1 using an 8% by mass aqueous solution of ammonium sulfate as an electrolyte solution. Thereafter, electrolytic oxidation treatment was performed under the electric condition of 15 coulombs / g of total electric quantity. The critical tension of the electrolytically oxidized carbon fiber bundle was 66 mN / m.

The carbon fiber bundle after the electrolytic oxidation treatment was dipped once in a sizing bath (concentration 37 g / l) containing an epoxy-modified urethane as a main ingredient by dipping. Thereafter, a compressed air was blown to the carbon fiber bundle traveling on the roller surface using a blower (wind velocity: 2.8 m / 0.1 sec). After passing through the drying process, it was wound on a bobbin using a winder to obtain sizing agent-adhered carbon fiber having a density of 1.79 g / cm ³ , a strand strength of 5300 MPa, and a sizing agent luminous intensity ratio (I / S) of 0.7. . The sizing agent adhesion amount, sizing agent luminescence intensity ratio (I / S), fuzz, and MPF of the obtained sizing agent-adhered carbon fiber bundle are shown in Table 1.

  Using this sizing agent-adhered carbon fiber bundle, a pressure vessel for evaluation of breaking strength was manufactured according to the above-mentioned evaluation method for pressure vessel breaking strength. When an internal pressure test was conducted on the obtained pressure container for evaluation of breaking strength, the breaking strength was 47 MPa and the tank breaking strength occurrence rate was 81.0%.

  In Comparative Example 1, since the sizing agent emission intensity ratio (I / S) was as low as 0.7 and the sizing agent was not sufficiently impregnated into the inner layer portion of the carbon fiber bundle, the tank fracture strength expression ratio of the obtained pressure vessel Was a low value.

Comparative Example 2
In the carbon fiber bundle before electrolytic oxidation treatment obtained in Example 1, 8% by mass ammonium sulfate aqueous solution is used as the electrolyte solution as the electrolyte solution without impregnating the carbon fiber bundle with the electrolytic solution, and the total amount of electricity is 10 coulomb / g The electrolytic oxidation treatment was performed under the following electrical conditions. The critical tension of the electrolytically oxidized carbon fiber bundle was 40 mN / m.

The carbon fiber bundle after the electrolytic oxidation treatment was dipped once in a sizing bath (concentration 38 g / l) containing an epoxy-modified urethane as a main ingredient by dipping. Thereafter, a compressed air was blown to the carbon fiber bundle traveling on the roller surface using a blower (wind velocity 3.5 m / 0.1 sec). After passing through the drying process, it was wound on a bobbin using a winder to obtain sizing agent-adhered carbon fiber having a density of 1.79 g / cm ³ , a strand strength of 5000 MPa, and a sizing agent luminous intensity ratio (I / S) of 0.6. . The sizing agent adhesion amount, sizing agent luminescence intensity ratio (I / S), fuzz, and MPF of the obtained sizing agent-adhered carbon fiber bundle are shown in Table 1.

  Using this sizing agent-adhered carbon fiber bundle, a pressure vessel for fracture strength evaluation was manufactured according to the aforementioned evaluation method for pressure vessel fracture strength. When an internal pressure test was conducted on the obtained pressure container for evaluation of breaking strength, the breaking strength was 47 MPa, and the tank breaking strength development rate was 80.0%.

  In Comparative Example 2, since the sizing agent emission intensity ratio (I / S) was as low as 0.6 and the sizing agent was not sufficiently impregnated into the inner layer portion of the carbon fiber bundle, the tank fracture strength expression ratio of the obtained pressure vessel Was a low value.

Claims (1)

The sizing agent luminescence count of the outer layer portion of the carbon fiber bundle, which is obtained by adhering a sizing agent at 0.8 to 3.0% by mass to a carbon fiber bundle having a critical tension of 70 to 90 mN / m, and measured by a cathode luminescence method The number (S) and the sizing agent luminescence count number (I) of the inner layer portion of the carbon fiber bundle measured by the cathode luminescence method are the following formula (1)
1.2 <I / S <2.0 (1)
(Here, the sizing agent luminescence count number (I) means the luminescence count number measured at the cross section when the sizing agent-adhered carbon fiber bundle is cut into two equal parts along the axis, and the sizing agent The light emission count number (S) refers to the light emission count number measured in the non-cross section of the cut carbon fiber bundle)
A sizing agent-adhered carbon fiber bundle for filament winding molding, which satisfies the following relationship: