JP2022117562A - Sizing agent-coated carbon fiber bundle and method for producing the same - Google Patents

Abstract

To provide a sizing agent-coated carbon fiber bundle that ensures proper resin impregnation in an aqueous slurry impregnation process and keeps its moldability or processability not impaired when processed into a prepreg.SOLUTION: A sizing agent-coated carbon fiber bundle is coated with at least a water-soluble compound (A) having an amino group and/or a compound (B) having a polyalkylene glycol. As measured by X-ray photoelectron spectroscopy (XPS), its surface oxygen level (O/C) is 0.28 or more and 0.45 or less and surface nitrogen level (N/C) is 0.05 or more and 0.20 or less. The sizing agent-coated carbon fiber bundle satisfies the following (i) and (ii): (i) after water washing for 50 seconds, the surface oxygen level (O/C) is 0.15 or more and 0.25 or less and the surface nitrogen level (N/C) is 0.15 or more and 0.30 or less; and (ii) the number of adhesion sites is 20 or less as evaluated by a water dispersion.SELECTED DRAWING: Figure 1

Description

The present invention has high adhesion to thermoplastic resins typified by polyphenylene sulfide, polyallyl ether ketone, polyether sulfone, polyamideimide, etc., has excellent resin impregnation in an aqueous slurry impregnation process, and is processed into a prepreg. The present invention relates to a sizing agent-coated carbon fiber bundle coated with a sizing agent that does not sometimes impair moldability and workability, and a method for producing the same.

Carbon fiber is light in weight and has excellent strength and elastic modulus. Therefore, it is used as a composite material in combination with various matrix resins for aircraft parts, spacecraft parts, automobile parts, ship parts, civil engineering and construction materials, sporting goods, and the like. used in the field of Although the properties required for carbon fiber reinforced composite materials differ slightly depending on the application, adhesion at the interface between carbon fiber and matrix resin is one of the most important basic properties, and much research and technology has been devoted to the surface treatment of carbon fibers. has been developed.

Conventionally, thermosetting resins typified by epoxy resins have often been used as matrix resins in carbon fiber composite materials. However, the molding of carbon fiber reinforced composite materials with a thermosetting resin as the matrix resin requires a large-sized apparatus such as an autoclave, and requires a relatively long time to control the curing reaction. There were some problems in terms of molding costs, such as. Therefore, in recent years, attention has been paid to carbon fiber reinforced composite materials that use thermoplastic resin as the matrix resin, because they do not require a curing reaction, which makes it possible to significantly shorten the molding time and do not necessarily require large-scale equipment such as autoclaves. is rising.

For the reasons described above, conventional technological developments related to surface treatment of carbon fibers have been conducted mainly for thermosetting resins. For example, in the case of epoxy resin, there are abundant hydroxyl groups generated during the curing reaction, polar groups such as amines used as curing agents, and reactive functional groups such as glycidyl groups. It was often done with an awareness of bonds and interactions. On the other hand, since thermoplastic resins differ greatly from thermosetting resins in terms of the types and amounts of functional groups present and the temperature range during molding, surface design suitable for thermoplastic resins is important.

As a surface treatment for thermoplastic resins, for example, Patent Document 1 proposes a method of applying polyethyleneimine as a sizing agent to carbon fiber bundles to improve adhesion with thermoplastic resins having few functional groups. ing. In addition, in Patent Document 2, a method of applying a sizing agent obtained by mixing polyethyleneimine with modified polyethylene glycol from the viewpoint of improving the adhesiveness with a thermoplastic resin and further improving processability in high-order processing of carbon fiber bundles. is proposed. Further, Patent Documents 3 and 4 propose conditions for optimizing the openability of carbon fiber bundles in various advanced processing processes.

Compositing a thermoplastic resin and carbon fibers requires a different approach than thermosetting resins, which often have a low viscosity in the uncured state and are easy to handle. For example, a melt impregnation method in which a melted thermosetting resin is impregnated, a solution impregnation method in which a solution of a thermoplastic resin dissolved in a solvent is impregnated and the solvent is removed, and a slurry made of fine particles of a thermoplastic resin is passed through. Various processes are performed according to the type and purpose of the thermoplastic resin to be combined with the carbon fiber, such as a slurry impregnation method in which carbon fibers are impregnated. Among these methods, the water-based slurry impregnation method using water as a dispersion medium is superior from the viewpoint of economy and the like.

JP 2013-166924 A JP 2019-065441 A JP 2019-210587 A JP 2019-210586 A

However, the conventional techniques described above have the following problems.

In Patent Document 1, polyethyleneimine is used as a sizing agent to improve adhesion with polypropylene, which is a matrix resin. Not clear.

In Patent Document 2, there is an idea to combine polyethyleneimine and modified polyethylene glycol to achieve both adhesion to thermoplastic resins and processability in high-order processing, but the suitability for water-based slurry impregnation processes is not clear. .

Patent Documents 3 and 4 have the idea of optimizing mechanical openability and air openability, which are important for uniform impregnation, respectively, but their applicability to water-based slurry impregnation processes is not clear.

As described above, in order to achieve both improvement in adhesiveness to thermoplastic resins and processability and fiber-opening properties in specific high-order processing processes, techniques for using polyethyleneimine and modified polyethylene glycol in combination have been proposed. There was no focus on the water-based slurry impregnation process, and no suggestion of sizing agent-coated carbon fiber bundles suitable for this particular process.

Therefore, the object of the present invention is to apply a sizing agent that has high adhesion to thermoplastic resins, excellent resin impregnation in the water-based slurry impregnation process, and does not easily impair moldability and workability when processed into prepregs. An object of the present invention is to provide a sizing agent-coated carbon fiber bundle and a method for producing the same.

The present invention for solving the above-mentioned problems is a sizing agent-coated carbon fiber bundle coated with a water-soluble compound (A) having at least an amino group and/or a compound (B) containing polyalkylene glycol, The surface oxygen concentration (O/C) measured by X-ray photoelectron spectroscopy (XPS) is 0.28 or more and 0.45 or less, and the surface nitrogen concentration (N/C) is 0.05 or more and 0.20 or less. It is a sizing agent-coated carbon fiber bundle that satisfies the following (i) and (ii).
(i) Surface oxygen concentration (O/C) after washing for 50 seconds by the water washing method described later is 0.15 or more and 0.25 or less, and surface nitrogen concentration (N/C) is 0.15 or more and 0.30 It is below.
(ii) The number of fixations evaluated by a water dispersion test described later is 20 or less.

Further, the method for producing a sizing agent-coated carbon fiber bundle of the present invention is the above-described method for producing a sizing agent-coated carbon fiber bundle, in which the carbon fiber bundle is dried at 180 to 240° C. after passing through the step of applying the sizing agent to the carbon fiber bundle. It is characterized by having a drying step for drying.

According to the present invention, it has high adhesion to thermoplastic resins typified by polyphenylene sulfide, polyallyl ether ketone, polyether sulfone, polyamideimide, etc., has excellent resin impregnation in an aqueous slurry impregnation process, and is processed into a prepreg. It is possible to provide a sizing agent-coated carbon fiber bundle coated with a sizing agent that does not impair moldability and workability.

FIG. 1 is a diagram showing a 50-second washing evaluation method.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated.

The sizing agent-coated carbon fiber bundle of the present invention is a sizing agent-coated carbon fiber bundle obtained by coating at least a water-soluble compound (A) having an amino group and/or a compound (B) containing polyalkylene glycol, wherein X The surface oxygen concentration (O/C) measured by line photoelectron spectroscopy (XPS) is 0.28 or more and 0.45 or less, and the surface nitrogen concentration (N/C) is 0.05 or more and 0.20 or less. , a sizing agent-coated carbon fiber bundle that satisfies the following (i) and (ii).
(i) Surface oxygen concentration (O/C) after washing for 50 seconds by the water washing method described later is 0.15 or more and 0.25 or less, and surface nitrogen concentration (N/C) is 0.15 or more and 0.30 It is below.
(ii) The number of fixations evaluated by a water dispersion test described later is 20 or less.

In the following description, the surface oxygen concentration (O/C) is sometimes simply referred to as O/C, and the surface nitrogen concentration is simply referred to as N/C. A water-soluble compound having at least an amino group may also be simply referred to as a water-soluble compound (A) having an amino group or a compound (A). Furthermore, compound (B) containing polyalkylene glycol may be simply described as compound (B).

According to studies by the present inventors, when using a sizing agent containing a water-soluble compound (A) having an amino group in the carbon fiber bundle and/or a compound (B) containing polyalkylene glycol, resin It was found that impregnability tends to decrease, and mechanical properties tend to decrease due to thermal decomposition of the sizing agent remaining on the carbon fiber surface during prepreg production. For this problem, the O / C and N / C of the carbon fiber bundle and the O / C and N / C after washing the carbon fiber bundle with water under specific conditions are controlled, and the number of adhesions evaluated by a water dispersion test is controlled to a certain value or less, high adhesiveness with thermoplastic resin, excellent resin impregnation in water-based slurry impregnation process, and sizing agent coating that does not impair moldability and workability when processed into prepreg. It has been found that carbon fiber bundles can be obtained.

In the present invention, the sizing agent refers to a compound added to the surface of the carbon fiber bundles in order to enhance the adhesiveness with the resin and improve the handling properties of the carbon fiber bundles. It suffices that the agent contains at least a water-soluble compound (A) having an amino group and/or a compound (B) containing a polyalkylene glycol, and a sizing agent other than the compound (A) and the compound (B) is contained. may

The sizing agent-coated carbon fiber bundle constituting the present invention must contain at least a water-soluble compound (A) having an amino group and/or a compound (B) containing polyalkylene glycol, and the sizing agent is applied. It is necessary that each sizing agent-coated carbon fiber bundle satisfies specific conditions. In the present invention, either a water-soluble compound (A) having at least an amino group or a compound (B) containing a polyalkylene glycol may be used, or a water-soluble compound (A) having at least an amino group and a poly Both compounds (B) containing alkylene glycol may be used.

A carbon fiber bundle coated with a sizing agent containing a water-soluble compound (A) having an amino group tends to exhibit excellent adhesiveness with a thermoplastic resin. As a result, the mechanical properties of thermoplastic resin moldings using carbon fiber bundles coated with the sizing agent are often improved. Although the mechanism is not clear, amino groups are highly polar, and strong interactions such as hydrogen bonding with highly polar oxygen-containing structures such as carboxyl groups and hydroxyl groups in the carbon fiber bundle surface and resin make excellent It is thought that it expresses adhesiveness.

Polyalkylene glycol is a compound obtained by polymerizing multiple alkylene glycols, and has the general formula HO--(CnHmO)sH, or the formula R1-O--(CnHmO)s-H, or the formula R2-O--(CnHmO). It is a compound represented by s-R3 (wherein R1, R2, and R3 each represent a substituent having 1 or more carbon atoms). A compound containing polyalkylene glycol exhibits moderate lubricity, and a carbon fiber bundle coated with a compound containing polyalkylene glycol has excellent handleability, and can suppress the generation of fluff in the process of processing into a prepreg. be.

Whether the sizing agent-coated carbon fiber bundle contains a water-soluble compound having an amino group or a compound containing polyalkylene glycol is evaluated by evaluating the sizing agent-coated carbon fiber bundle itself, or by removing the sizing agent from the sizing agent-coated carbon fiber bundle. It can be determined by extracting and evaluating. For example, a sizing agent-coated carbon fiber bundle is measured by time-of-flight secondary ion mass spectrometry (TOF-SIMS), and a method of identifying a compound by detecting characteristic fragment ion species, or a method of identifying a compound by extracting a sizing agent with water. There is a method of identifying a compound by combining structural evaluation from an IR spectrum obtained by infrared spectroscopy after freeze-drying, proton NMR, carbon NMR, and mass spectral analysis of the freeze-dried product.

Furthermore, the sizing agent-coated carbon fiber bundle of the present invention has a surface oxygen concentration (O/C) of 0.28 or more and 0.45 or less measured by X-ray photoelectron spectroscopy (XPS), and a surface nitrogen concentration (N /C) must be 0.05 or more and 0.20 or less. The sizing agent-coated carbon fiber bundle having an O/C of 0.28 or more and 0.45 or less and an N/C of 0.05 or more and 0.20 or less has high handleability and high adhesion to the matrix resin. It becomes compatible in a high dimension. If the O/C is less than 0.28, the amount of the polyalkylene glycol-containing compound applied to the carbon fiber bundle is small, resulting in poor handleability. Further, when the O/C is larger than 0.45, the amount of the compound containing polyalkylene glycol becomes excessive, and it is easy to stabilize properties such as thermal stability in the resulting thermoplastic resin molded article. If N/C is less than 0.05, the water-soluble compound having an amino group is not sufficiently applied, and sufficient adhesiveness cannot be obtained. Moreover, when N/C is larger than 0.20, a large amount of the water-soluble compound having an amino group is present on the outermost surface of the carbon fiber bundle, which deteriorates the handleability. It is preferable that O / C is 0.30 or more and 0.45 or less, and N / C is 0.06 or more and 0.18 or less, and O / C is 0.32 or more and 0.45 or less, and N / It is more preferable that C is 0.07 or more and 0.15 or less.

In addition, the sizing agent-coated carbon fiber bundle of the present invention has an O/C of 0.15 or more and 0.25 or less and an N/C of 0.15 after washing the carbon fiber bundle with water by the method described in Examples. It must be 0.30 or less. The fact that the O/C after washing with water under specific conditions is lower than that before washing with water indicates that the compound containing polyalkylene glycol has been removed by washing with water, and the O/C is 0.15 or more and 0.25 or less. A decrease in the thermal stability of the resin can be suppressed by controlling the In addition, the fact that the N/C after washing with water under specific conditions is higher than that before washing with water indicates that a water-soluble compound having an amino group is present on the outermost surface of the carbon fiber after washing with water. By controlling /C to 0.15 or more and 0.30 or less, high adhesiveness can be obtained even after passing through the aqueous slurry impregnation process. O/C after washing with water is preferably 0.16 or more and 0.23 or less, and N/C is preferably 0.17 or more and 0.28 or less, O/C is 0.17 or more and 0.21 or less, and , N/C is more preferably 0.19 or more and 0.26 or less.

Furthermore, the sizing agent-coated carbon fiber bundle constituting the present invention has an O/C of 0.15 or more and 0.25 or less and an N/C of 0.10 or more after heating at 300 ° C. for 5 minutes in the air. It is preferably 0.25 or less. In the molding process of highly heat-resistant thermoplastic prepreg represented by polyphenylene sulfide, polyallyl ether ketone, polyether sulfone, polyamideimide, etc., in many cases, the thermoplastic resin penetrates sufficiently into the fiber bundle to improve impregnation. In addition, it is common to heat to 320° C. or higher for molding. In the process of molding such a prepreg, the sizing agent is partly decomposed by heating at a high temperature to generate decomposed products. In particular, when the sizing agent decomposes at a high temperature of 320° C. or higher, which is the same as the molding temperature, the properties such as the thermal stability of the molded product may be affected. Therefore, by decomposing and removing the sizing agent at a temperature lower than the molding temperature, it is possible to stabilize properties such as thermal stability in the obtained thermoplastic resin molded article. Here, the fact that the O / C after heating at 300 ° C. for 5 minutes is lower than before the heat treatment means that the compound containing polyalkylene glycol is decomposed and removed during the heat treatment, and after the heat treatment. By controlling the O/C to be 0.15 or more and 0.25 or less, the deterioration of the thermal stability of the resin can be suppressed. In addition, the fact that the N/C after heating at 300°C for 5 minutes is higher than before the heat treatment indicates that a water-soluble compound having an amino group is present on the outermost surface of the carbon fiber after the heat treatment. By controlling N/C to 0.10 or more and 0.25 or less, high adhesion to the matrix resin can be obtained even at high molding temperatures. After heating at 300 ° C. for 5 minutes in air, O / C is preferably 0.16 or more and 0.24 or less, and N / C is preferably 0.11 or more and 0.24 or less, and O / C is 0 0.17 or more and 0.23 or less, and N/C is more preferably 0.12 or more and 0.23 or less.

O/C and N/C of the carbon fiber bundle can be determined by X-ray photoelectron spectroscopy according to the following procedure. First, the carbon fiber bundles from which dirt and the like adhering to the surface of the carbon fiber bundles have been removed are cut into 20 mm pieces, spread on a copper sample support, and then arranged in a row. Maintain the medium at 1×10 −8 Torr. The binding energy value of the main peak (peak top) of C1s is adjusted to 284.6 eV as a peak correction value associated with charging during measurement. The C1s peak area is determined by drawing a straight baseline in the range of 282-296 eV. The O1s peak area is determined by drawing a straight baseline in the range of 528-540 eV, and the N1s peak area is determined by drawing a straight baseline in the range of 391-411 eV. Here, the surface oxygen concentration and the surface nitrogen concentration can be calculated as an atomic number ratio from the ratio of the O1s or N1s peak area to the C1s peak area using the apparatus-specific sensitivity correction value.

In the present invention, the number of fixation should be 20 or less, preferably 15 or less, more preferably 12 or less. In the present invention, sticking refers to a portion where single fibers constituting a carbon fiber bundle are locally stuck to each other, and is evaluated by a water dispersion test described later. As a result of investigations by the present inventors, it has been found that the smaller the number of fixations, the easier it is to improve resin impregnation in the water-based slurry impregnation process described below, and the easier it is to obtain a high-quality prepreg. If the number of fixation is 20 or less, the resin impregnability tends to be high. The number of fixation can be controlled by the composition of the sizing agent, the heat treatment temperature after application of the sizing agent, and the like.

The sizing agent-coated carbon fiber bundles constituting the present invention have an absorbance of 0.01 or less at 600 nm of the sizing agent-coated carbon fiber bundle extract measured by the method described in Examples, and an absorbance of 0 at 300 nm. It is preferably 0.10 or less. The absorbance at 600 nm represents the elution amount of fragile oxides adhering to the fiber surface caused by the carbon fiber oxidation treatment, and the absorbance at 300 nm represents the elution amount of the sizing agent applied to the surface. By setting the absorbance at 600 nm to 0.01 or less, the sizing agent sufficiently reacts with the surface of the carbon fiber, and high adhesion to the matrix resin can be obtained. Further, by setting the absorbance at 300 nm to 0.10 or less, excess adhesion of the sizing agent is eliminated, and the properties such as thermal stability of the obtained thermoplastic resin molding can be easily stabilized. The absorbance at 600 nm is more preferably 0.008 or less, even more preferably 0.006 or less. Also, the absorbance at 300 nm is more preferably 0.08 or less, and even more preferably 0.06 or less.

The amount of the sizing agent attached to the sizing agent-coated carbon fiber bundle constituting the present invention is preferably 0.10% by mass or more and 0.50% by mass or less based on 100% by mass of the sizing agent-coated carbon fiber bundle. In the present invention, the adhesion amount of the sizing agent is evaluated by the method described later. When the amount of the sizing agent attached is 0.10% by mass or more, the sizing agent uniformly attached to the surface improves the abrasion resistance of the carbon fiber bundle, suppresses the generation of fluff during manufacturing and processing, and spreads the fibers. It is possible to improve quality such as smoothness of the carbon fiber sheet having good properties. From the viewpoint of improving the IFSS, that is, the adhesiveness to the thermoplastic resin, the adhesion amount of the sizing agent is more preferably 0.15% by mass or more, and further preferably 0.20% by mass or more. On the other hand, when the amount of the sizing agent attached is 0.50% by mass or less, it is easy to stabilize properties such as thermal stability in the resulting thermoplastic resin molded article. The amount of the sizing agent attached is more preferably 0.45% by mass or less, and even more preferably 0.40% by mass or less. The adhesion amount of the sizing agent can be controlled by the concentration of the sizing agent solution.

The mass W _A of the water-soluble compound (A) having an amino group used in the present invention and the mass W _B of the compound (B) containing polyalkylene glycol preferably satisfy the formula (a).
0.20<= _WA /( _WA + _WB )<=0.50... Formula (a).

When W _A /(W _A +W _B ) satisfies the formula (a), the adhesiveness can be enhanced, and properties such as the thermal stability of the resin can be easily stabilized when processed into a prepreg. If W _A /(W _A +W _B ) is less than 0.20, the amount of the water-soluble compound (A) having an amino group may be too small to obtain sufficient adhesion. If W _A /(W _A +W _B ) is greater than 0.50, the adhesiveness is high, but the thermal stability of the resin may be reduced when processed into a prepreg, resulting in a reduction in mechanical properties. W _A /(W _A +W _B ) is more preferably 0.25 or more and 0.45 or less, further preferably 0.30 or more and 0.40 or less.

Specific examples of the water-soluble compound (A) having an amino group used in the present invention include aliphatic amine compounds and aromatic amine compounds. Among them, aliphatic amine compounds are preferable from the viewpoint of exhibiting high adhesiveness. A possible reason for the high adhesiveness of the aliphatic amine compound is that it has a very high polarity compared to other compounds having an amino group.

Specific examples of aliphatic amine compounds include diethylenetriamine, triethylenetetramine, dicyandiamide, tetraethylenepentamine, dipropylenediamine, piperidine, N,N-dimethylpiperazine, triethylenediamine, polyamidoamine, polyethyleneimine, and polypropyleneimine. , polybutyleneimine, 1,1-dimethyl-2-methylethyleneimine, 1,1-dimethyl-2-propylethyleneimine, N-acetylpolyethyleneimine, N-propionylpolyethyleneimine, N-butyrylpolyethyleneimine, N- Examples include polyalkyleneamines such as pararylpolyethyleneimine, N-hexanoylpolyethyleneimine, N-stearoylpolyethyleneimine, derivatives thereof, and mixtures thereof.

Among aliphatic amine compounds, compounds having 3 or more functional groups in one molecule are preferably used because they tend to have high adhesiveness. In particular, polyalkyleneimines are preferably used because they easily increase the amount of functional groups contained in one molecule and easily improve adhesiveness. The reason why the adhesiveness of a compound having 3 or more functional groups in one molecule tends to be high is thought to be that the polarity of the molecule tends to increase as the amount of functional groups increases.

Specific examples of aromatic amine compounds include 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, benzidine, triaminophenol, triglycidylaminocresol, 2,4,6 -triaminophenol, 1,2,3-triaminopropane, 1,2,3-triaminobenzene, 1,2,4-triaminobenzene, 1,3,5-triaminobenzene and derivatives thereof, and their derivatives and the like.

The weight average molecular weight Mw of compound (A) is preferably 2,500 or less. The weight average molecular weight Mw is measured by a gel permeation chromatography (GPC) method and obtained using pullulan as a standard substance. The larger the Mw, the higher the viscosity of the sizing agent, so a large force may be required to separate the carbon fibers that are sticking together via the sizing agent. By setting Mw to 2,500 or less, the viscosity, which is an index of the easiness of movement of the sizing agent, is lowered, and by weakening the force binding the carbon fibers together, the spreadability of the carbon fiber bundles tends to be improved. Mw of compound (A) is more preferably 2,000 or less, and even more preferably 1,500 or less. On the other hand, in terms of decomposition, the higher the Mw, the easier it is to control volatilization and decomposition of the sizing agent at high temperatures. Mw of compound (A) is preferably 500 or more, more preferably 650 or more.

The compound (B) containing the polyalkylene glycol preferably has a weight average molecular weight Mw of 500 or more and 1000 or less and an SP value of 21 or more. If the Mw is less than 500, the sizing agent is easily decomposed by the heat in the drying process after applying it, so it may be difficult to stably apply it to carbon fibers. In addition, when the Mw is greater than 1000, the sizing agent has high heat resistance, making it difficult to decompose during the prepreg processing process, which affects the properties such as thermal stability of the resulting thermoplastic resin molded product. There is Moreover, when the SP value is 21 or more, it becomes easy to suppress sticking, and the impregnation property of the resin can be improved. Here, the SP value is a generally known solubility parameter, and is widely used as an index of solubility and polarity. The SP value defined in the present invention is Polym. Eng. Sci. , 14(2), 147-154 (1974), calculated from the molecular structure based on the method of Fedors. The SP value is more preferably 21.5 or higher, even more preferably 22 or higher. Although the upper limit of the SP value is not particularly defined, it is considered that about 30 is a realistic standard.

The compound (B) containing polyalkylene glycol is preferably a polypropylene glycol derivative having no aromatic ring. A compound having an aromatic ring has high heat resistance, so that it becomes difficult to decompose during a prepreg processing step, and may affect properties such as thermal stability of the obtained thermoplastic resin molded article. Since polypropylene glycol derivatives have high thermal decomposability, it is possible to achieve both coating stability in the sizing coating process and removability during the prepreg processing process by adjusting the molecular weight. In the present invention, the term "derivatives of polypropylene glycol" is a general term for compounds in which a part of the structure of polypropylene glycol is replaced with other substituents or structures.

The number of terminals of the compound (B) containing the polyalkylene glycol is preferably 3 or more and 5 or less. When the number of terminals is 3 or more, sticking can be effectively suppressed, and the impregnability of the resin can be enhanced. On the other hand, when the number of terminals is greater than 5, the heat resistance of the sizing agent increases, making it difficult to decompose during the prepreg processing process, which affects the properties such as thermal stability of the resulting thermoplastic resin molded product. I have something to give.

Specific examples of the compound (B) containing polyalkylene glycol used in the present invention include polyethylene glycol, polypropylene glycol, polybutylene glycol, copolymers thereof, and derivatives thereof. Examples include polyethylene glycol fatty acid esters (C4-C18), polyoxyethylene monoalkyl ethers (C4-C18), polyoxyethylene dialkyl ethers (C4-C18), bisphenol A ethylene oxide adducts, ethylenediamine polyoxyethylene adducts. , triethanolamine polyoxyethylene adduct, aromatic diamine polyoxyethylene adduct, sucrose polyoxyethylene adduct, sorbitol polyoxyethylene adduct, sucrose polyoxyethylene adduct, trimethylolpropane polyoxyethylene adduct, Polyethylene glycol derivatives such as pentaerythrol polyoxyethylene adduct, polyoxyethylene triol, glycerin polyoxyethylene adduct, diglycerin polyoxyethylene adduct, polyglycerin polyoxyethylene adduct, diethylenetriamine polyoxyethylene adduct, polypropylene Glycol fatty acid ester (C4-C18), polyoxypropylene monoalkyl ether (C4-C18), polyoxypropylene dialkyl ether (C4-C18), bisphenol A propylene oxide adduct, ethylenediamine polyoxypropylene adduct, triethanolamine poly Oxypropylene adduct, aromatic diamine polyoxypropylene adduct, sucrose polyoxypropylene adduct, sorbitol polyoxypropylene adduct, sucrose polyoxypropylene adduct, trimethylolpropane polyoxypropylene adduct, pentaerythrol polyoxy Propylene adducts, polyoxypropylene triols, glycerin polyoxypropylene adducts, diglycerin polyoxypropylene adducts, polyglycerin polyoxypropylene adducts, polypropylene glycol derivatives such as diethylenetriamine polyoxypropylene, ethylenediamine polyether polyols, triethanolamine Polyether polyol, aromatic diamine polyether polyol, sucrose polyether polyol, sorbitol polyether polyol, sucrose polyether polyol, trimethylol derivatives of copolymers of polyethylene glycol/polypropylene glycol such as propane polyether polyol, pentaerythrol polyether polyol, glycerin polyether polyol, diglycerin polyether polyol, polyglycerin polyether polyol, diethylenetriamine polyether polyol, and A mixture thereof and the like are included.

A third component may be added to the sizing agent in the sizing agent-coated carbon fiber bundle constituting the present invention as long as the effect of the present invention is not impaired. For example, by adding a smoothing agent such as a nonionic surfactant, the wet FF friction coefficient of the single yarn surface layer in the carbon fiber bundle can be lowered, and the resin impregnability can be improved. The wet FF friction coefficient is the coefficient of friction when sizing agent-coated carbon fiber bundles are rubbed against each other in the longitudinal direction in a water-wet state, and can be obtained by the method described in Examples. When the wet FF friction coefficient is 0.45 or less, the resin-impregnating property tends to be high, and when it is 0.38 or less, the resin-impregnating property tends to be even higher.

When a nonionic surfactant is added as a third component, specific examples thereof include polyoxyethylene alkyl ethers such as polyoxyethylene dodecyl ether, polyoxyethylene oleyl ether, and polyoxyethylene stearyl ether, polyoxyethylene poly Oxypropylene glycol, polyoxyethylene alkylphenyl ether, sorbitan fatty acids such as sorbitan monooleate, sorbitan monostearate, sorbitan sesquioleate, sorbitan coconut oil fatty acid, sorbitan monopalmitate, sorbitan tristearate, and sorbitan trioleate Esters, polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan trioleate, polyoxyethylene glycerin fatty acid esters such as polyoxyethylene glyceryl monooleate, polyoxyethylene sorbitan tetraoleate, etc. polyoxyethylene sorbitol fatty acid ester, polyoxyethylene hydrogenated castor oil; polyglycerin fatty acid ester, sucrose fatty acid ester, PEG monocaprylate, PEG monoheptylate, PEG monopelargonate, PEG monocaprate, PEG monolaurin acid ester, PEG monomyristate, PEG monopentadecylate, PEG monopalmitate, PEG monolinoleate, PEG dilaurate, PEG monooleate, PEG dioleate, PEG monostearate, PEG distearate, PEG dicaprylate, PEG diheptylate, PEG dipelargonate, PEG dicaprate, PEG dilaurate, PEG dimyristate, PEG dipentadecylate, PEG dipalmitate, PEG dilinoleate Examples include polyethylene glycol fatty acid esters such as esters. "PEG" is an abbreviation for "polyethylene glycol". When the nonionic surfactant is added as the third component, the amount to be added is preferably 10% by mass or less in 100% by mass of the total amount of the sizing agent.

In the sizing agent-coated carbon fiber bundle of the present invention, the sizing agent preferably does not substantially contain an epoxy group-containing compound. Here, "substantially free of a compound" means that such a compound does not exist at all, or even if it exists in the form of an additive, it is 1% by mass or less in 100% by mass of the total amount of the sizing agent. means that A highly reactive epoxy group reacts with the amino group of the amine compound to form a strong crosslinked structure. Therefore, when the sizing agent does not substantially contain a compound having an epoxy group, the formation of a crosslinked structure between carbon fiber single yarns is suppressed, and the spreadability is easily improved.

Although the carbon fiber bundle used in the present invention is not particularly limited, polyacrylonitrile-based carbon fibers are preferably used from the viewpoint of mechanical properties. The polyacrylonitrile-based carbon fiber bundle used in the present invention is obtained by subjecting a carbon fiber precursor fiber made of a polyacrylonitrile-based polymer to a flameproofing treatment at a maximum temperature of 200 to 300 ° C. in an oxidizing atmosphere, and then heating it in an inert atmosphere to a maximum It is obtained by carrying out a preliminary carbonization treatment at a temperature of 500 to 1,200° C., followed by a carbonization treatment at a maximum temperature of 1,200 to 2,000° C. in an inert atmosphere.

In the present invention, in order to improve the adhesiveness between the carbon fiber bundle and the thermoplastic resin, it is preferable to introduce oxygen-containing functional groups to the surface by subjecting the carbon fiber bundle to an oxidation treatment. Gas-phase oxidation, liquid-phase oxidation, and liquid-phase electrolytic oxidation are used as the oxidation treatment method. Liquid-phase electrolytic oxidation is preferably used from the viewpoint of high productivity and uniform treatment.

In the present invention, the electrolytic solution used in the liquid-phase electrolytic oxidation includes an acidic electrolytic solution and an alkaline electrolytic solution. Examples of acidic electrolytes include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, boric acid, and carbonic acid; organic acids such as acetic acid, butyric acid, oxalic acid, acrylic acid, and maleic acid; or ammonium sulfate and ammonium hydrogen sulfate. and the like. Among them, sulfuric acid and nitric acid, which are strongly acidic, are preferably used. Specific examples of alkaline electrolytes include aqueous solutions of hydroxides such as sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide and barium hydroxide, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, Aqueous solutions of carbonates such as barium carbonate and ammonium carbonate, aqueous solutions of carbonates such as sodium hydrogencarbonate, potassium hydrogencarbonate, magnesium hydrogencarbonate, calcium hydrogencarbonate, barium hydrogencarbonate and ammonium hydrogencarbonate, ammonia, tetraalkylammonium hydroxide and an aqueous solution of hydrazine.

In the present invention, the amount of oxygen-containing functional groups to be introduced into the carbon fiber bundle is the surface oxygen concentration, which is the ratio of the number of atoms of oxygen (O) and carbon (C) on the fiber surface measured by X-ray photoelectron spectroscopy. (O/C) is preferably in the range of 0.08 to 0.30. When the O/C is 0.08 or more, the number of carboxyl groups and hydroxyl groups on the surface of the carbon fiber increases, the interaction with the sizing agent becomes stronger, and the adhesiveness improves. O/C is more preferably 0.10 or more, still more preferably 0.12 or more. On the other hand, from the viewpoint of reduction in the strength of the carbon fiber itself due to oxidation, the smaller the O/C, the better, and the O/C is preferably 0.30 or less. It is more preferably 0.25 or less, and still more preferably 0.22 or less.

Next, the method for producing the sizing agent-coated carbon fiber bundle of the present invention will be described.
First, means for applying (applying) the sizing agent to the carbon fiber bundles in the present invention will be described.

In the present invention, the sizing agent is preferably diluted with a solvent and used as a uniform solution. Examples of such solvents include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, dimethylformamide, and dimethylacetamide. Therefore, water is preferably used.

Examples of application means include a method of immersing the carbon fiber bundle in the sizing agent solution through a roller, a method of contacting the carbon fiber bundle with a roller to which the sizing agent solution is attached, and a method of atomizing the sizing agent solution and applying it to the carbon fiber bundle. There are methods such as spraying, but in manufacturing the sizing agent-coated carbon fiber bundle of the present invention, a method of immersing the carbon fiber bundle in the sizing agent solution via a roller is preferably used. The means for applying the sizing agent may be either a batch type or a continuous type, but the continuous type is preferably used because of its high productivity and small variation. It is also a preferred embodiment to vibrate the carbon fiber bundle with ultrasonic waves when applying the sizing agent.

The concentration of the sizing agent solution used in the method of immersing the carbon fiber bundle in the sizing agent solution via a roller may be controlled so that the amount of the sizing agent attached to the sizing agent-coated carbon fiber bundle is the desired value.

The method for producing a sizing agent-coated carbon fiber bundle according to the present invention preferably includes a drying step of drying at 180 to 240° C. after the step of applying the sizing agent to the carbon fiber bundle.

In the present invention, after applying the sizing agent solution, it is preferable to obtain a sizing agent-coated carbon fiber bundle by contacting the carbon fiber bundle with a heated roller, for example, by contact drying means. The carbon fiber bundle introduced into the heated roller is pressed against the heated roller by tension and dried rapidly, so that the flat shape of the carbon fiber bundle widened by the heated roller is easily fixed by the sizing agent. A flattened carbon fiber bundle has a smaller contact area between single fibers, and thus tends to be more openable.

Moreover, in the present invention, after passing through a heated roller as a preliminary drying step, heat treatment may be further added as a second drying step. Either a contact heating method or a non-contact heating method may be employed for the heat treatment as the second drying step. By performing the heat treatment, the diluting solvent remaining in the sizing agent can be further removed, and the frictional properties of the sizing agent-coated carbon fiber bundle can be stabilized. The heat treatment conditions are typically preferably set between 180° C. and 240° C., and may be appropriately adjusted so as to satisfy the above-described requirements for the sizing agent-coated carbon fiber bundle of the present invention. In general, the higher the heat treatment temperature, the lower the wet FF friction coefficient tends to decrease, while the sticking of single yarns tends to increase. With this general relationship in mind, adjustments can be made accordingly. Heat treatment can also be carried out with microwave irradiation and/or infrared irradiation.

In the present invention, the sizing agent-coated carbon fiber bundle is preferably combined with a thermoplastic resin (D) to form a thermoplastic resin composition.

The thermoplastic resin (D) in the present invention includes polyketone resins, polyetherketone resins, polyethernitrile resins, polyimide resins, polyamideimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, and polyarylene sulfide resins. , polyether ether kenton resin, polyphenylene ether resin, polyoxymethylene resin, polyamide resin, polyester resin, polycarbonate resin, fluorine resin, styrene resin and polyolefin resin. At least one thermoplastic selected from the group consisting of Resins are preferred.

The thermoplastic resin composition of the present invention can be preferably used in the form of molding material such as prepreg or UD tape.

Next, a method for producing a molded article using the thermoplastic resin composition of the present invention will be described. The method for producing a molded article of the present invention preferably includes a step of heating to 300° C. or higher when obtaining the thermoplastic resin composition using the sizing agent-coated carbon fiber bundle and the thermoplastic resin (D). By heating and molding at 300° C. or higher in the molding step, the thermoplastic resin sufficiently permeates into the fiber bundle and the impregnation property is improved, thereby improving the physical properties of the thermoplastic resin composition.

As specific examples of molded articles obtained by molding the thermoplastic resin composition of the present invention, in addition to molded articles as final products, molding materials used for producing molded articles (for example, the following exemplified pellets, stampable sheets, UD tapes and prepregs, etc.).

Specific examples of the molded article of the present invention include molding materials such as pellets, stampable sheets, UD tapes, and prepregs, as well as personal computers, displays, OA equipment, mobile phones, personal digital assistants, facsimiles, compact discs, and portables. Electric and electronic equipment such as MDs, portable radio cassettes, PDAs (personal digital assistants such as electronic notebooks), video cameras, digital still cameras, optical equipment, audio equipment, air conditioners, lighting equipment, recreational goods, toys, and other electrical and electronic equipment housings and internal members such as trays and chassis, their cases, mechanical parts, construction materials such as panels, motor parts, alternator terminals, alternator connectors, IC regulators, potentiometer bases for light gear, suspension parts, exhaust gas valves, etc. Various valves, fuel related pipes, exhaust or intake system pipes, air intake nozzle snorkels, intake manifolds, various arms, various frames, various hinges, various bearings, fuel pumps, gasoline tanks, CNG tanks, engine coolant joints, carburetor mains Body, carburetor spacer, exhaust gas sensor, cooling water sensor, oil temperature sensor, brake pad wear sensor, throttle position sensor, crankshaft position sensor, air flow meter, brake butt wear sensor, thermostat base for air conditioner, heating hot air flow control Valves, brush holders for radiator motors, water pump impellers, turbine vanes, wiper motor related parts, distributors, starter switches, starter relays, wire harnesses for transmissions, window washer nozzles, air conditioner panel switch substrates, fuel-related electromagnetic valves Coils, fuse connectors, battery trays, AT brackets, headlamp supports, pedal housings, handles, door beams, protectors, chassis, frames, armrests, horn terminals, step motor rotors, lamp sockets, lamp reflectors, lamp housings, brake pistons, Noise shield, radiator support, spare tire cover, seat shell, solenoid bobbin, engine oil filter, ignition device case, under cover, scuff plate, pillar trim, propeller shaft, wheel, fender, fascia Automotive parts such as bumpers, bumper beams, bonnets, aero parts, platforms, cowl louvers, roofs, instrument panels, spoilers and various modules, motorcycle related parts, members and outer panels, landing gear pods, winglets, spoilers, edges , rudders, elevators, failings, ribs and other aircraft-related parts, members and outer panels, windmill blades and other molded parts. In particular, it is preferably used for aircraft members, windmill blades, automobile outer panels, electronic device housings, trays, chassis, and the like.

EXAMPLES Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

<Method for measuring adhesion amount of sizing agent>
After weighing 2.0 ± 0.5 g of the sizing-coated carbon fiber bundle (W1) (unit: g, read to the fourth decimal place), electric The sizing agent was completely pyrolyzed by leaving it in an oven (capacity 120 cm ³ ) for 15 minutes. Then, it was transferred to a container in a dry nitrogen stream at 20 liters/minute, cooled for 15 minutes, and then weighed (W2) (unit: g, read to the fourth decimal place) and heated by W1-W2. A weight loss ΔW was obtained. This heating loss ΔW was divided by the mass W1 of the sizing agent-coated carbon fiber bundle before thermal decomposition as shown in the formula (b), and expressed as a percentage of 100 to obtain the adhesion amount of the sizing agent. The adhesion amount of the sizing agent was measured twice, the average value was obtained, and the result was rounded to the third decimal place and used as the adhesion amount of the sizing agent in the present invention.
Adhesion amount (% by mass) of sizing agent=ΔW/W1×100 (b).

<Method for measuring wet FF friction coefficient>
A stainless steel SUS304 bar with a diameter of 50 mm was fixed parallel to the ground so as not to rotate, and a sizing agent-coated carbon fiber bundle to be evaluated was wound around the surface of the bar. The sizing agent-coated carbon fiber bundle was wound so as to cover the surface of the bar with a width of 8 cm without gaps. At this time, the already wound portion and the bundle to be newly wound next thereto were wound so that the ends of each bundle overlap each other by about 1 mm. In addition, in order to prevent slack, the winding start and winding end were fixed by sticking them on the surface of the bar with tape. Then, the same sizing agent-coated carbon fiber bundle was wrapped around the center of the 8 cm wide range covered with the sizing agent-coated carbon fiber bundle 1.5 times, that is, so that the contact angle was 3π (rad). It was wound vertically downward. At this time, it was typically wound with an interval of 3 to 5 mm in the width direction so as not to overlap itself. The sizing agent-coated carbon fiber bundle wound 1.5 times was uniformly wetted with 5 mL of clean water. At this time, a dropper was used to wet the whole circumference well. Next, a weight (T1 = 0.08 g/tex) was attached to one end of the sizing agent-coated carbon fiber bundle wound 1.5 times, and a spring scale was attached to the other end. The tension T2 (g/tex) was obtained by pulling at a speed of 1 m/min, reading the force when the sizing agent-coated carbon fiber bundle wound 1.5 turns started to move, and dividing it by the fineness of the sizing agent-coated carbon fiber bundle. asked for Measurement was completed within 10 seconds from the start of wetting with water. The wet FF friction coefficient was calculated from the following formula. The measurement was performed twice, and the average value was taken as the wet FF friction coefficient. The measurement bobbins used were placed in the measurement atmosphere temperature and humidity conditions (measurement conditions: 23±3° C./60±5%) two hours or more before the measurement.

Wet FF friction coefficient = ln (T2/T1)/θ
T2: Tension when the carbon fiber bundle begins to move T1: Weight mass (= 0.25 g/tex)
θ: contact angle (=3πrad).

<Method for measuring the number of fixation>
It was evaluated by the water dispersion test 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, the mixture was filtered on a quantitative filter paper (grade: 5C, manufactured by ADVANTEC) with a diameter of 110 mm using a separable funnel with an inner diameter of 95 mm. Filtration was performed by suction filtration using an aspirator, and the filter paper after filtration was air-dried by allowing it to stand for 2 hours in a place not exposed to wind. The filter paper was sandwiched between laminate films and passed through a laminator for lamination. The surface of the laminated filter paper was observed under a microscope under the conditions described below, and images of 16 fields of view were obtained. In order to acquire images of 16 fields of view without omission or duplication, 16 marks were made in advance with a marker in a grid pattern on the surface of the filter paper, and the images of 16 fields of view were captured so that these marks were near the center of the field of view. Acquired. 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. The image processing software used was open source software "imageJ", and was carried out as follows. First, read 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 use the “Analyze” command “Plot Profile” was selected to obtain a luminance profile along the line segment. The half-value width of the profile was read, and the actual size was converted into the "thickness" of the bundle of single yarns. Although the thicknesses of the adhesives are different from each other, no particular distinction was made in the present invention. The number of adhesions in each of the acquired images for 16 fields of view was counted and totaled for 16 fields of view to obtain the total number of adhesions. The above operation from dispersion/filtration was repeated twice, and the average value of the two adherence numbers was adopted as the adherence number in the present invention.
Microscope: Nikon SMZ1270
Camera: Nikon DS-Vi1
Monitor: Nikon DS-L3
Magnification: 1x Gain: 170
Exposure time: 100ms
Image mode: Full
Pixel resolution: 8 μm/pixel Recording mode: 1,600×1,200 pixels (12.8 mm×9.6 mm).

<Method for determining absorbance of carbon fiber extract>
The absorbance of the sizing agent-coated carbon fiber extract defined in the present invention was determined by the following procedure. 1.0 part by mass of the carbon fiber bundle was cut out, placed in a glass container with a lid of 20 cm ³ in volume, and 10.0 parts by mass of DMSO at 25° C. was added. The sizing agent and surface oxides adhering to the sizing agent-coated carbon fiber bundle were extracted by treating for 15 minutes under ultrasonic irradiation with an oscillation frequency of 40 kHz. The solution extracted from the carbon fiber was placed in a quartz cell with an optical path length of 1.0 cm, the absorbance at 200 to 900 nm was measured using a UV-visible spectrophotometer, and the absorbance at 300 nm and 600 nm was recorded using DMSO as a control solution.
The ultraviolet-visible spectrophotometer used was V-550 manufactured by JASCO Corporation.

<Method of washing carbon fiber bundle with water>
The sizing agent-coated carbon fiber bundle was washed with water according to the following procedure. The sizing agent-coated carbon fiber bundle 1a installed in the unwinding process 11 shown in FIG. After that, it is passed through the water 1e in the water washing tank 22 through the similar water washing tank front free roller 19, the water washing tank inside free roller 20, and the water washing tank free roller 21, and then continuously. It passes through a drying process 13 to dry the water and is wound up in a winding process 14.例文帳に追加The unwinding tension from the creel was 800 g, the process speed was 2.4 m/min, the water temperature was 25 ± 5°C, the diameter of the free roller in the washing tank was 150 mm, and the sizing agent-coated carbon fiber bundle and the free roller in the washing tank The contact angle of is πrad. In addition, the liquid surface is adjusted so that the underwater passage time in one washing tank is 25 seconds, and the total time in two washing tanks is 50 seconds. The drying step is non-contact drying, and the sizing agent-coated carbon fiber bundle 1b after washing with water is dried at a drying temperature of 150° C. for 1 minute to obtain a sizing agent-coated carbon fiber bundle 1c after washing with water and drying.

<Method for measuring interfacial shear strength (IFSS)>
A single yarn is extracted from the sizing agent-coated carbon fiber bundle, one resin film having a thickness of 0.52 mm is placed on the top and the bottom, and a molded plate having a thickness of 0.50 mm in which the carbon fiber single yarn is embedded is obtained by a hot press device. rice field. The heat press was set at a temperature of 380° C. and a pressure of 0.4 to 0.5 MPa. Dumbbell-shaped specimens for IFSS measurement were punched out from the molded plate and smoothed by sanding with No. 1200 sandpaper to avoid breakage from the new cross section created by the punching. A dumbbell-shaped sample was clamped at both ends and a tensile force was applied in the direction of the fiber axis (longitudinal direction) to produce a strain of 12% at a speed of 2.0 mm/min. After the test, the test piece was placed on a hot plate set at a temperature of 380° C. to melt the crystals, and when it became transparent, it was quenched by immersing it in water to make it transparent. Fragmented fiber lengths inside the sample that had been made transparent by heating were observed under a microscope. Further, the critical fiber length lc was calculated from the average broken fiber length la by the formula lc (μm)=(4/3)×la (μm). The strand tensile strength σ and the diameter d of the carbon fiber single yarn were measured, and the interfacial shear strength (IFSS), which is an index of the adhesive strength between the carbon fiber and the resin interface, was calculated by the following formula. D-1, which will be described later, was used as the resin film.
IFSS (MPa) = σ (MPa) x d (μm)/(2 x lc) (μm).
In the examples, the average of the number of measurements n=5 was used as the test result, and the results were classified into the following four stages according to the IFSS value.
S: IFSS is 38 (MPa) or more A: IFSS is 36 (MPa) or more and less than 38 (MPa) B: IFSS is 34 (MPa) or more and less than 36 (MPa) C: IFSS is less than 34 (MPa).

<Evaluation of prepreg formation and resin impregnation>
Six units of carbon fiber bundles to be evaluated were arranged in the width direction with 12,000 filaments as one unit and subjected to prepreg formation. In prepreg formation, the carbon fiber bundle is pulled out from the bobbin, run in the air for 3 m, passed through a water-based slurry tank in which thermoplastic resin fine particles are dispersed in water to pick up the resin, and a hot plate whose surface temperature is set to 120 ° C. Moisture is volatilized by continuously contacting with , and after passing through a melting chamber set at an atmospheric temperature of 380 ° C., by scraping the inner surface of a pressure die with a width of 30 mm set to a thickness of about 200 μm , to obtain a resin-impregnated prepreg. The water-based slurry is obtained by adding 2 to 4 parts by mass of thermoplastic resin fine particles to 100 parts by mass of water and 0.5 parts by mass of Brij (registered trademark) S100 (manufactured by Sigma-Aldrich) as a surfactant. A circulating pump was used to circulate and stir. The set temperature of the pressure die was 380°C. The amount of thermoplastic resin fine particles in the water-based slurry was finely adjusted so that the resin content of the finally obtained prepreg was 34% by mass. The take-up speed was 0.5 m/min. The thermoplastic resin fine particles used were D-2, which will be described later, in the form of a powder having an average particle size of 23 μm. Sensory evaluation was made on the resin impregnability of the obtained prepreg. Specifically, a prepreg having a width of about 30 mm was manually bent in the direction in which the fiber axis of the carbon fiber is bent (0-degree direction) and in the thickness direction to bend and break the prepreg. The edges caused by the bending fracture were visually observed and classified into the following five grades depending on how fluff appeared. Such bending evaluation was repeated 10 times, and the average score was adopted. In the present invention, in view of the fact that such evaluation is a sensory evaluation, the criteria for the rating AA is Comparative Example 9, the criteria for the rating C is Comparative Example 4, and the criteria for the rating D are Comparative Examples 5 and 8. , to prevent discrepancies by evaluators.
AA: No fluff is observed A: A fluff is slightly observed, but all are 1 mm or less in length B: A fluff exceeding 1 mm in length exists, but is slight compared to C C: Width less than 1 mm D: There are fluffs with a width of 1 mm or more D-2, which will be described later, was used as the resin fine particles.

<Evaluation of thermal stability of prepreg>
Differential scanning calorimetry (DSC measurement) was performed on the prepared prepreg test piece under the measurement conditions described below, and the cycle of heating and cooling was repeated twice. The peak top temperature of the crystallization peak during the second cycle temperature drop process was recorded as T1. In addition, the thermoplastic resin (D-2) was subjected to DSC measurement by the same measurement method, and the peak top temperature (T0) of the crystallization peak in the cooling process of the first cycle was read, T0 = 275.0 ° C. Met. The amount of change in the peak top when processed into a prepreg was calculated by T0-T1, and the thermal stability of the resin in the prepreg was evaluated. This measurement was performed three times, the average value was obtained, and the results were classified into the following four levels according to the amount of change in the peak top.
S: The amount of change in the peak top is less than 19.0°C A: The amount of change in the peak top is 19.0°C or more and less than 20.0°C B: The amount of change in the peak top is 20.0°C or more and 21.0°C Less than C: Peak top change amount is 21.0 ° C. or more DSC measurement conditions Sample amount: 10.0 mg (± 0.5 mg)
Measurement atmosphere: nitrogen (purity of 99.999% by volume or more)
Measurement condition:
1.Hold at 50°C for 1 minute.Rise from 50°C to 380°C at 2.50°C/min.Hold at 380°C for 3 minutes.Hold at 380°C for 3 minutes. Hold for 1 minute, temperature rise from 50°C to 380°C at 6.50°C/min; hold at 380°C for 30 minutes;

The compounds and thermoplastic resins used in each example and each comparative example are as follows.

Compound (A)
A-1: polyethyleneimine (Mw = 1,300, viscosity: 6,800 mPa s)
(“Lupasol” (registered trademark) G20 Waterfree manufactured by BASF Japan Ltd.)
Compound (B)
B-1: polyethylene glycol (Mw = 600, SP value = 21.7, number of terminals = 2)
(PEG600 manufactured by Sanyo Chemical Industries, Ltd.)
B-2: polyethylene glycol diglyceryl ether (Mw = 750, SP value = 23.6, number of terminals = 4)
("SC-E750" manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.)
B-3: polypropylene glycol (Mw = 600, SP value = 20.2, number of terminals = 2)
(“Sannics” (registered trademark) PP600 manufactured by Sanyo Chemical Industries, Ltd.)
B-4: polypropylene glycol glyceryl ether (Mw = 400, SP value = 23.7, number of terminals = 3)
(“Sannics” (registered trademark) GP400 manufactured by Sanyo Chemical Industries, Ltd.)
B-5: polypropylene glycol glyceryl ether (Mw = 1000, SP value = 20.2, number of terminals = 3)
(“Sannics” (registered trademark) GP1000 manufactured by Sanyo Chemical Industries, Ltd.)
B-6: polypropylene glycol diglyceryl ether (Mw = 750, SP value = 22.7, number of terminals = 4)
(“SC-P750” manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.)
B-7: polypropylene glycol diglyceryl ether (Mw = 1000, SP value = 21.2, number of terminals = 4)
("SC-P1000" manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.)
B-8: Sorbitol polypropylene glycol ether (Mw = 750, SP value = 23.8, number of terminals = 6)
(“Sannics” (registered trademark) SP750 manufactured by Sanyo Chemical Industries, Ltd.)
B-9: PEG monooleate (Mw = 600, SP value = 19.3, number of terminals = 2)
(“Ionet” (registered trademark) MO600 manufactured by Sanyo Chemical Industries, Ltd.)
B-10: PEG distearate (Mw = 4000, SP value = 19.0, number of terminals = 2)
(“Ionet” (registered trademark) DS4000 manufactured by Sanyo Chemical Industries, Ltd.)
Thermoplastic resin D-1: polyphenylene sulfide (glass transition temperature 89 ° C.)
(“Durafide” (registered trademark) PPS W-540 manufactured by Polyplastics Co., Ltd.)
D-2: Polyether ketone ketone ("KEPSTAN (registered trademark)" 7002 manufactured by Arkema).

(Example 1)
This embodiment consists of the following 1st to 5th steps.

・First step: A step of producing a carbon fiber bundle as a raw material Spinning and baking acrylonitrile copolymer, total filament number 12,000, total fineness 800 tex, strand tensile strength 5.1 GPa, strand tensile elasticity A carbon fiber bundle with a modulus of 240 GPa was obtained. Then, the carbon fiber bundle was subjected to electrolytic surface treatment using an aqueous solution of ammonium bicarbonate as an electrolytic solution with an amount of electricity of 80 coulombs per 1 g of the carbon fiber bundle. The carbon fiber bundle subjected to the electrolytic surface treatment was then washed with water and dried in hot air to obtain a carbon fiber bundle as a raw material. The carbon fiber bundle obtained after this step had an O/C of 0.20 and an N/C of 0.09.

・ Second step: Step of attaching a sizing agent to the carbon fiber bundle Using (A-1) as the compound (A) and (B-1) as the compound (B), (A-1) 3 parts by mass, ( B-1) 7 parts by weight were weighed and dissolved in about 1,540 parts by weight of water to obtain an about 0.65% by weight aqueous solution in which the sizing agent was uniformly dissolved. 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 15 seconds as a preliminary drying step. As a drying step, heat treatment was performed in heated air at a temperature of 200° C. for 60 seconds to obtain a sizing agent-coated carbon fiber bundle. The adhesion amount of the sizing agent was adjusted to 0.35% by mass with respect to 100% by mass of the total surface-treated carbon fiber bundle coated with the sizing agent.
The evaluation results are summarized in Table 1.

- Third step: A step of washing the sizing agent-coated carbon fiber bundle with water The sizing agent-coated carbon fiber bundle obtained in the second step is subjected to sizing as described in the above <Method of washing carbon fiber bundle>. The agent-coated carbon fiber bundle was washed with water to obtain a sizing agent-coated carbon fiber bundle after washing with water for 50 seconds. The obtained carbon fiber bundles were evaluated by X-ray photoelectron spectroscopy (XPS).

・Fourth step: A step of heat-treating the sizing agent-coated carbon fiber bundle. About 2.0 g of the sizing agent-coated carbon fiber bundle obtained in the second step is prepared, and heated to 450°C in a nitrogen stream of 50 ml/min. The sizing agent was thermally decomposed by leaving it for 5 minutes in an electric furnace (capacity: 120 cm ³ ) set to a temperature. Then, the carbon fiber bundle was evaluated by X-ray photoelectron spectroscopy (XPS) after being transferred to a container in a dry nitrogen stream of 20 liters/minute and cooled for 15 minutes.

- Fifth step: A step of producing a prepreg Using the sizing agent-coated carbon fiber bundle obtained in the second step, a prepreg was produced by the method described in <Evaluation of prepreg formation and resin impregnation> above. . Also, using the obtained prepreg, the thermal stability of the prepreg was evaluated by the method described in <Evaluation of thermal stability of prepreg> above.

(Example 2-10)
The types and compounding ratios of the compounds (A) and (B) used for the sizing agent and the adhesion amount of the sizing agent were changed to the respective values shown in Table 1, and the sizing agent-coated carbon fiber bundle was produced in the same manner as in Example 1. were obtained and various evaluations were performed. The results are summarized in Table 1.

(Comparative Example 1-9)
The sizing agent was applied in the same manner as in Example 1 by changing the types and compounding ratios of the compounds (A) to (B) used for the sizing agent, the amount of sizing agent adhered, and the drying temperature to the values shown in Table 2. A carbon fiber bundle was obtained and various evaluations were performed. The results are summarized in Table 2.

(Comparative Example 10)
A carbon fiber bundle was obtained in the same manner as in Example 1 except that the sizing agent was not adhered, and various evaluations were performed. The results are summarized in Table 2.

According to the present invention, according to the present invention, the adhesiveness with thermoplastic resins represented by polyphenylene sulfide, polyaryletherketone, polyethersulfone, polyamideimide, etc. is high, and the resin impregnation in the water-based slurry impregnation process. It is possible to provide a sizing agent-coated carbon fiber bundle coated with a sizing agent that is excellent and does not easily impair moldability and workability when processed into a prepreg. The thermoplastic resin composite using the present invention is lightweight and has excellent strength, so it is suitably used in many fields such as aircraft members, spacecraft members, automobile members, ship members, civil engineering and construction materials, and sporting goods. be able to.

11: Unwinding process 12: Washing process 13: Drying process 14: Winding process 15: Free roller before washing tank 16: Free roller in washing tank 17: Free roller after washing tank 18: Washing tank 19: Free roller before washing tank 20: Free roller in washing tank 21: Free roller after washing tank 22: Washing tank 1a: Carbon fiber bundle coated with sizing agent 1b: Carbon fiber bundle coated with sizing agent after washing 1c: Carbon fiber bundle coated with sizing agent after washing and drying 1d: water 1e: water

Claims (9)

A sizing agent-coated carbon fiber bundle coated with a water-soluble compound (A) having at least an amino group and/or a compound (B) containing polyalkylene glycol, and measured by X-ray photoelectron spectroscopy (XPS) Surface oxygen concentration (O/C) is 0.28 or more and 0.45 or less, and surface nitrogen concentration (N/C) is 0.05 or more and 0.20 or less, satisfying the following (i) and (ii) Sizing agent coated carbon fiber bundle.
(i) The surface oxygen concentration (O/C) after washing for 50 seconds by the water washing method described below is 0.15 or more and 0.25 or less, and the surface nitrogen concentration (N/C) is 0.15 or more and 0. .30 or less.
(ii) The number of fixations evaluated by the water dispersion test described below is 20 or less.
<Method of washing carbon fiber bundle with water>
The sizing agent-coated carbon fiber bundle is washed with water according to the following procedure. The sizing agent-coated carbon fiber bundle 1a installed in the unwinding process 11 shown in FIG. After that, it is passed through the water 1e in the water washing tank 22 through the similar water washing tank front free roller 19, the water washing tank inside free roller 20, and the water washing tank free roller 21, and then continuously. It passes through a drying process 13 to dry the water and is wound up in a winding process 14.例文帳に追加The unwinding tension from the creel was 800 g, the process speed was 2.4 m/min, the water temperature was 25±5° C., the diameter of the free roller in the water washing tank was 150 mm, and the distance between the sizing agent-coated carbon fiber bundle and the free roller in the water washing tank was 150 mm. The contact angle is πrad. In addition, the liquid surface is adjusted so that the underwater passage time in one washing tank is 25 seconds, and the total time in two washing tanks is 50 seconds. The drying step is non-contact drying, and the sizing agent-coated carbon fiber bundle 1b after washing with water is dried at a drying temperature of 150° C. for 1 minute to obtain a sizing agent-coated carbon fiber bundle 1c after washing with water and drying.
<Method for measuring adhesion number by water dispersion test>
Sodium dioctyl sulfosuccinate (manufactured by Tokyo Kasei Kogyo Co., Ltd.), which is an anionic surfactant, is 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 into a length of 5 mm is put into a dispersion medium that has been stirred by a magnetic stirrer at a rotation speed of 200 rpm. After stirring for 30 seconds, the mixture is filtered on a quantitative filter paper (grade: 5C, manufactured by ADVANTEC) with a diameter of 110 mm using a separable funnel with an inner diameter of 95 mm. Filtration is performed by suction filtration using an aspirator, and the filter paper after filtration is air-dried by allowing it to stand for 2 hours in a place not exposed to wind. The filter paper is sandwiched between laminate films and passed through a laminator for lamination. The surface of the laminated filter paper is observed under a microscope under the conditions described below to obtain images of 16 fields of view. In order to acquire images of 16 fields of view without omission or duplication, 16 marks were made in advance with a marker in a grid pattern on the surface of the filter paper, and the images of 16 fields of view were captured so that these marks were near the center of the field of view. get. A lump 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, and that has a thickness of 40 μm or more is 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 judge. The image processing software is the open source software "imageJ" and is performed as follows. First, read 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 use the “Analyze” command “Plot profile" to obtain a luminance profile along the line segment. The half-value width of the profile is read, and the actual size is converted into the "thickness" of the bundle of single yarns. The adhesives are different in thickness, but are not particularly distinguished. The number of adhesions in each of the acquired images for 16 fields of view is counted and totaled for 16 fields of view to obtain the total number of adhesions. The above operation from dispersion/filtration is repeated twice, and the average value of the two adherence numbers is adopted as the adherence number.
Microscope: Nikon SMZ1270
Camera: Nikon DS-Vi1
Monitor: Nikon DS-L3
Magnification: 1x Gain: 170
Exposure time: 100ms
Image mode: Full
Pixel resolution: 8 μm/pixel Recording mode: 1,600×1,200 pixels (12.8 mm×9.6 mm) After heating at 300 ° C. for 5 minutes in air, the surface oxygen concentration (O / C) is 0.15 or more and 0.25 or less, and the surface nitrogen concentration (N / C) is 0.10 or more and 0.25 or less. The sizing agent-coated carbon fiber bundle according to claim 1. The sizing agent-coated carbon fiber bundle according to claim 1 or 2, wherein the absorbance at 600 nm of the extract obtained by extraction by the following extraction operation is 0.01 or less and the absorbance at 300 nm is 0.10 or less. .
<Extraction operation>
1.0 part by mass of carbon fiber bundle is cut out, placed in a lidded glass container with a volume of 20 cm ³ , and 10.0 parts by mass of DMSO at 25° C. is added. The sizing agent and surface oxides adhering to the sizing agent-coated carbon fiber bundle are extracted by treating for 15 minutes under ultrasonic irradiation with an oscillation frequency of 40 kHz. The sizing agent-coated carbon fiber bundle according to any one of claims 1 to 3, wherein the amount of the sizing agent attached is 0.10% by mass or more and 0.50% by mass or less in 100% by mass of the sizing agent-coated carbon fiber bundle. . The mass W _A of the water-soluble compound (A) having at least an amino group and the mass W _B of the compound (B) containing the polyalkylene glycol satisfy the formula (a). Sizing agent coated carbon fiber bundle.
0.20≦W _A /(W _A +W _B )≦0.50 Expression (a) The sizing agent-coated carbon fiber bundle according to any one of claims 1 to 5, wherein the polyalkylene glycol-containing compound (B) has a weight average molecular weight Mw of 500 or more and 1000 or less and an SP value of 21 or more. The sizing agent-coated carbon fiber bundle according to any one of claims 1 to 6, wherein the compound (B) containing polyalkylene glycol is a polypropylene glycol derivative having no aromatic ring. The sizing agent-coated carbon fiber bundle according to any one of claims 1 to 7, wherein the number of terminals of the compound (B) containing polyalkylene glycol is 3 or more and 5 or less. The method for producing a sizing agent-coated carbon fiber bundle according to any one of claims 1 to 8, wherein the sizing agent has a drying step of drying at 180 to 240°C after the step of applying the sizing agent to the carbon fiber bundle. A method for producing coated carbon fiber bundles.

Images