JP6356497B2 - Sizing agent-attached fiber bundle and method for producing the same - Google Patents

Description

  The present invention relates to a sizing agent-attached fiber bundle, and more particularly, to a fiber bundle having an optimum sizing agent attached to a composite material composed of fibers and a matrix resin, and a method for producing the same.

  Composite materials with matrix resin reinforced with fibers are lightweight, yet have excellent strength, rigidity, dimensional stability, etc., so they are used in office equipment, automobiles, computers (IC trays, notebook PC housings (housings)) Etc.) and the demand is increasing year by year. However, the reinforcing fibers used in this composite material have different chemical compositions and molecular structures from the matrix resin, so that improvement of affinity and adhesion is a major issue.

  In particular, when reinforcing fibers are used in the form of fiber bundles in the matrix resin, in addition to the above-mentioned interface problems such as affinity and adhesion between the fibers and the matrix resin, various There was a problem. For example, there are problems such as the stability of the process of cutting or opening the fiber bundle and the processability in the process of impregnating the matrix resin. When the state of the fiber bundle is not stable, the impregnation degree is greatly different when the inner layer portion is impregnated with the high viscosity resin, and stable physical properties of the composite material cannot be obtained.

  Conventionally, various sizing agents have been studied for the purpose of increasing the affinity between the fiber bundle and the matrix resin. For example, Patent Document 1 discloses a method for improving the strength of a composite material by attaching an epoxy emulsion sizing agent to a fiber bundle to improve the interfacial adhesion between the fiber bundle and the matrix resin. Alternatively, Patent Document 2 discloses a method of treating with an acid-modified polyolefin-based sizing agent when thermoplastic resin polypropylene is used as a matrix.

  However, these methods have the problem that although the interfacial adhesive strength is improved, the texture of the fiber bundle tends to be hard, and the handleability and workability are remarkably lowered. Furthermore, the physical properties of the finally obtained composite material have been insufficient. This is because the reinforcing fiber bundle is not uniformly dispersed in the composite material, and a sufficient reinforcing effect cannot be obtained.

In particular, when the matrix resin of the composite material is a high-viscosity thermoplastic resin, or when the reinforcing fiber bundle is further widened, opened, split, and cut to randomly apply the fiber bundle and impregnate with the resin In the case of mats, this problem was remarkable.
The development of a fiber bundle that can satisfy the multiple problems such as resin impregnation into the inner layer of the fiber bundle, adhesion between the matrix resin and the fiber, and sufficiently improve the physical properties of the composite material has been awaited. It was.

JP-A-4-170435 JP 2006-124847 A

  An object of the present invention is to provide a sizing agent-attached fiber bundle that is optimal for a composite material such as a random mat and satisfies the texture and convergence, and a method for producing the same.

The sizing agent-attached fiber bundle of the present invention is a fiber bundle having a sizing agent attached to the surface, the entire shape of the fiber bundle is a flat fiber bundle, and the thickness of the fiber bundle is 200 μm or less. It contains an amine adduct salt obtained by neutralizing an amine adduct , which is a reaction product of a compound and an amine compound, and polyurethane.
Furthermore, the weight blending ratio of the amine adduct and polyurethane is preferably 1: 9 to 9: 1, and the fiber bundle is preferably a carbon fiber bundle.
Another manufacturing method of the sizing agent-attached fiber bundle of the present invention is a fiber bundle composed of reinforcing fibers , wherein the overall shape of the fiber bundle is a flat fiber bundle, and the thickness of the fiber bundle is 200 μm or less. A treatment liquid containing an amine adduct salt neutralized with an amine adduct , which is a reaction product of an epoxy compound and an amine compound, and a polyurethane emulsion is attached to the surface of the fiber bundle and dried .
Furthermore, this invention includes invention of the composite material which consists of a reinforced fiber and matrix resin obtained from these sizing agent adhesion fiber bundles.

  ADVANTAGE OF THE INVENTION According to this invention, the sizing agent adhesion fiber bundle which is optimal for composite materials, such as a random mat, and satisfies the texture and convergence, and its manufacturing method are provided.

  The sizing agent-attached fiber bundle of the present invention is a fiber bundle having a sizing agent attached to the surface, and the sizing agent contains an amine adduct, which is a reaction product of an epoxy compound and an amine compound, and polyurethane. Furthermore, the polyurethane contained in the sizing agent is preferably a poorly water-soluble polyurethane resin derived from an emulsion or a dispersion, and more preferably a thermoplastic polyurethane resin. The amine adduct contained in the sizing agent is preferably water-soluble.

  Here, examples of the fibers that are preferably used in the sizing agent-attached fiber bundle of the present invention include various reinforcing fibers that can reinforce the matrix resin. Specifically, as such reinforcing fibers, various inorganic fibers such as carbon fibers, glass fibers, ceramic fibers, silicon carbide fibers, aromatic polyamide fibers (aramid fibers), polyethylene fibers, polyethylene terephthalate fibers, polybutylene terephthalate fibers, Preferable examples include various organic fibers such as polyethylene naphthalate fiber, polyarylate fiber, polyacetal fiber, PBO fiber, polyphenylene sulfide fiber, and polyketone fiber. Among them, carbon fibers, glass fibers, and aromatic polyamide fibers are preferable as the fibers suitable for the present invention, and polyacrylonitrile (PAN) that can obtain a light-weight and high-strength fiber-reinforced composite material having particularly good specific strength and specific elastic modulus. ) Based carbon fiber.

  In the present invention, these reinforcing fibers are used as a fiber bundle. If the number of filaments (single yarn) constituting the fiber bundle is 10 or more, the fiber bundle state is obtained, but it is preferably 100 or more, and more preferably 1000 to 100,000. When the sizing agent-attached fiber bundle that is a particularly preferred embodiment is a carbon fiber bundle, it is preferably 3000 to 80000 from the viewpoint of productivity, and more preferably in the range of 6000 to 50000. . If the number of filaments constituting the fiber bundle is too small, the flexibility of the fiber bundle is increased and the handling property is improved, but the productivity of the reinforcing fiber tends to be lowered. On the other hand, when the number is too large, the production of the fiber bundle becomes difficult, and the surface treatment agent tends not to be sufficiently treated. For example, when the reinforcing fiber is carbon fiber, if it exceeds 80000, it becomes difficult to sufficiently complete the flame resistance or infusibilization treatment of the carbon fiber precursor fiber, and the mechanical properties of the carbon fiber finally obtained Tends to decrease.

  The average diameter of each reinforcing fiber (single fiber) constituting the fiber bundle is preferably in the range of 3 to 20 μm. A more preferable average diameter range is 4 to 15 μm, and further 5 to 10 μm. When the average diameter of the reinforcing fibers is too small, it is necessary to increase the total number of fibers in order to obtain the same reinforcing effect. In that case, especially when reinforcing the matrix resin using short fibers, the fiber component becomes bulky as a result, the volume fraction of the fibers in the composite material cannot be increased, and a composite material having excellent mechanical strength is obtained. It may be difficult to obtain. This tendency is particularly remarkable in the case of inorganic fibers such as carbon fibers. On the other hand, if the average diameter of the reinforcing fibers exceeds 20 μm, it tends to be difficult to ensure sufficient fiber strength. For example, when the reinforcing fiber is a carbon fiber, the flame resistance or infusibilization treatment of the carbon fiber precursor fiber cannot be sufficiently completed, and the mechanical properties of the finally obtained carbon fiber tend to be lowered. .

  The overall shape of the fiber bundle is preferably a flat fiber bundle. This is because the sizing agent applied to the inside of the fiber bundle and the matrix resin used for the subsequent composite material are more easily diffused. In particular, when the composite material is finally manufactured, the time until the matrix resin is impregnated in the fiber bundle is proportional to the square of the thickness of the fiber bundle in the case of a flat fiber bundle. For this reason, in order to complete impregnation in a short time, it is preferable to widen the fiber bundle and reduce the thickness of the sizing agent-attached fiber bundle. The impregnation time can be shortened efficiently. Specifically, the thickness of the fiber bundle is preferably 200 μm or less. Of course, even if the fiber bundle is too thin, the bulk is unnecessarily high, particularly when a short fiber bundle made of short fibers is used, and the handling property and moldability tend to be lowered. From this viewpoint, the thickness of the fiber bundle is preferably 10 μm or more. Furthermore, the thickness of the fiber bundle is preferably in the range of 30 to 150 μm, more preferably in the range of 50 to 120 μm.

  The width of the sizing agent-attached fiber bundle of the present invention is preferably 5 mm or more, and particularly preferably in the range of 10 to 100 mm. The flatness of the fiber bundle (width / thickness of the fiber bundle) is preferably 10 times or more, particularly 50 to 400 times. The length of the fiber bundle is preferably in the range of 1 to 100 mm. Furthermore, it is preferable that it is the range of 5-50 mm. By making the fiber bundle particularly short with such a high flattening rate, the fiber bundle can be easily opened in a later step, so that it becomes easy to process into a random mat shape. A composite material made through such a random mat shape is a composite material particularly suitable for industrial production because of its high molding speed and excellent physical properties.

The sizing agent-attached fiber bundle of the present invention is one in which a sizing agent is attached to the surface of the fiber bundle as described above. The sizing agent contains an amine adduct and polyurethane.
The amine adduct contained in this sizing agent is a reaction product of an epoxy compound and an amine compound. Further, the amine adduct is preferably water-soluble, and is preferably a linear thermoplastic resin, not a three-dimensional network structure that is so-called thermosetting. From such a point of view, it is preferable to use an alicyclic epoxy resin as a starting material which has poor reactivity due to steric hindrance and is difficult to form a three-dimensional network structure. Further, it is preferably a polymer rather than a low molecular weight compound such as a monomer or oligomer. For example, the number of units of the epoxy compound and the amine compound is preferably a polymer of 10 or more. The amine adduct preferably has an alicyclic hydrocarbon structure in the molecular skeleton.

  Further, the sizing agent used in the present invention contains polyurethane together with such an amine adduct. Furthermore, the polyurethane contained in the sizing agent is preferably a water-insoluble polyurethane resin derived from an emulsion or dispersion, particularly a thermoplastic polyurethane resin. Thermoplastic polyurethane resin is a resin that has both supple elasticity like rubber and toughness like hard plastic. For this reason, by using a polyurethane resin derived from an emulsion or a dispersion, it is possible to enhance the convergence of the sizing agent-attached fiber bundle and to impart an appropriate drape to the fiber bundle. From the viewpoint of heat resistance, it is preferable to use a polyester-based or polycarbonate-based polyurethane resin.

  By using such a sizing agent for the surface treatment of reinforcing fibers that take the form of fiber bundles in particular, high fiber spreadability and process passability of the fiber bundle are ensured. Furthermore, when such a reinforcing fiber is used for a composite material, it is possible to achieve both high adhesion to the matrix resin and impregnation. Such a sizing agent used in the present invention is particularly suitable for the present invention as a sizing agent for a fiber-reinforced composite material composed of reinforcing fibers and a matrix resin.

Further details of the amine adduct preferably used in the present invention will be described.
The amine adduct used in the present invention is a reaction product of an epoxy compound and an amine compound. Furthermore, the amine adduct used in the present invention is a reaction product of an epoxy compound and an amine compound, and the component ratio (molar ratio) of the epoxy compound and the amine compound is preferably slightly excess of the amine compound. Is preferably in the range of 1: 1.01 to 1: 1.1. Here, if the content of one of the epoxy compound or the amine compound is excessive, it is not preferable because a monomer or an oligomer is formed without forming a polymer.

  Furthermore, the amine adduct used in the present invention is basically preferably a thermoplastic resin compound in which an epoxy group derived from an epoxy compound is blocked. If there is a slight amount of unreacted epoxy group in the amine adduct, the molecular weight tends to be low, and the adhesiveness tends to decrease. In addition, in the reinforcing fiber manufacturing process, a slight amount of unreacted epoxy groups tend to form a three-dimensional network structure between amine adducts, and inhibit adhesion to the reinforcing fibers. The composite physical property of the composite material finally obtained falls.

  And it is preferable that the surface tension in 250 degreeC of the amine adduct which consists of the reaction product of the epoxy compound and amine compound contained in this fiber processing agent is 25 mN / m or more. By setting the surface tension of the polymer when heated to 25 mN / m or more, the composite physical properties can be kept higher. In particular, the amine adduct preferably has a surface tension at 250 ° C. of 27 to 40 mN / m. When the amine adduct adhering to the surface of the sizing agent adhering fiber bundle has a very large surface tension as described above, it is preferable to further increase the surface free energy of the fiber bundle to be used in advance. By doing so, the amine adduct does not aggregate on the fiber surface and can be spread more easily. That is, when the sizing agent of the present invention is used for the surface treatment liquid and then the fiber bundle is heated and dried, the polymer spreads more uniformly on the fiber surface without aggregation. As a result, finally, it is possible to further increase the composite physical properties using such a sizing agent-attached fiber bundle. In addition, the large surface tension of the amine adduct used in the present invention is due to a functional group derived from a polar term and a hydrogen bond term included in the molecular structure. Therefore, when it has such a high surface tension, it will adhere | attach very strongly with the reinforcing fiber to be used. The filament (single yarn) constituting the sizing agent-attached fiber bundle is strongly bound to each other, and has an effect of further increasing the convergence of the fiber bundle. Such a sizing agent-attached fiber bundle is a sizing agent-attached fiber bundle particularly suitable for manufacturing a random mat described later. Here, the surface tension is a parameter that depends on the intermolecular force, and is a value that determines the intramolecular cohesive force by the polar term or hydrogen bond term in the molecule. It is possible to increase the surface tension by replacing the carbon element in the skeleton of the epoxy compound or amine compound with an oxygen element or a nitrogen element.

  However, if the surface tension is too large, the sizing agent applied to the reinforcing fiber surface tends to melt and aggregate during heat treatment. Then, this sizing agent is inhibited from spreading on the surface of the reinforcing fiber, and conversely, the physical properties tend to decrease. That is, when the surface tension is too large, the matrix impregnation property to the reinforcing fibers and, consequently, the composite physical properties of the composite material finally obtained tend to be lowered. Therefore, in the present invention, polyurethane is used in combination with the sizing agent. The combined use of polyurethane also reduces the surface tension and adjusts the cohesive force.

  The heat treatment step for removing the solvent and the like from the emulsion coated on the reinforcing fiber surface is generally at most 250 ° C., and an appropriate fiber bundle can be obtained by defining the physical properties at this temperature. Is possible. The particularly preferable range of the surface tension of the high molecular weight amine adduct at 250 ° C. is preferably in the range of 29 to 35 mN / m.

  And as an epoxy compound which comprises the amine adduct used for this invention, the thing used for a normal epoxy resin can be used. Examples thereof include epoxy compounds such as glycidyl ether type, glycidyl amine type, glycidyl ester type, and olefin oxidation (alicyclic) type. In order to obtain a linear polymer which is a more preferable form, an epoxy compound having a plurality of epoxy groups, preferably two, is particularly preferable.

  Furthermore, the epoxy compound used in the present invention preferably has an alicyclic epoxy group. Such an olefin oxidation (alicyclic) type alicyclic epoxy compound easily causes steric hindrance, and therefore has low reactivity and hardly forms a three-dimensional network structure. For example, when this alicyclic epoxy resin is used, a linear polymer can be easily formed by thermal reaction with the amine compound described below in the absence of a catalyst.

In particular, taking into account the high reactivity, the epoxy compound preferably has an ester bond in the molecule, and particularly preferably an epoxy compound in which an ester bond exists between two alicyclic epoxies. For example, as the epoxy compound used in the present invention, 3 ′, 4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (manufactured by Daicel Corporation, Celoxide “CEL-2021P”, molecular weight 252.3) is preferably used. .
These epoxy compounds may be used alone or in combination of two or more. Moreover, you may mix and use another epoxy resin in the range which does not impair the effect of this invention.

  Next, the amine compound constituting the amine adduct used in the present invention will be described in detail. As the amine compound used in the present invention, it is preferable to use a bifunctional or higher amine compound. In particular, a bifunctional amine compound that is easy to obtain a linear polymer is preferable. As such amine compounds, for example, trade names “JEFFAMINE D-230”, “JEFFAMINE D-400”, “JEFFAMINE D-2000”, “JEFFAMINE D-4000”, “JEFFAMINE HK-511”, “JEFFAMINE ED-” "600", "JEFFAMINE ED-900", "JEFFAMINE ED-2003", "JEFFAMINE EDR-148", "JEFFAMINE EDR-176", "JEFFAMINE XTJ-582", "JEFFAMINE XTJ-578", "JEFFJIN2" ”,“ JEFFAMINE XTJ-548 ”,“ JEFFAMINE XTJ-559 ”,“ JEFFAMINE T-403 ”,“ JEFFAM ” NE T-3000 "," JEFFAMINE T-5000 "(or more, HUNTSMAN Co., Ltd.) can also be used commercially available products, such as.

  As the amine compound used in the present invention, an amine compound having an aromatic structure, such as diaminodiphenylsulfone or diaminodiphenylmethane, can be used. However, an amine having an aromatic structure is preferable. It is preferable not to contain a compound. This is because when the fiber bundle of the present invention is used as a composite material, the aromatic structure tends to slightly inhibit the adhesion with the matrix resin.

  The fiber treatment agent of the present invention uses an amine adduct composed of the epoxy compound and the amine compound as described above, but the amine adduct preferably has an alicyclic hydrocarbon structure in the molecular skeleton. Furthermore, it is preferable that the epoxy compound has an alicyclic epoxy group. Among these, the amine adduct used in the present invention is preferably composed of an alicyclic epoxy compound and an aliphatic amine compound. Moreover, it is preferable that an amine compound has an alicyclic structure. In particular, it is preferable to use a mixture of an amine compound having a saturated alicyclic hydrocarbon structure and an amine compound having a linear aliphatic structure as the amine compound. Such an aliphatic amine compound and an alicyclic epoxy resin are preferably used. It is preferable to use a polymer which is a reaction product obtained by reacting with. By using such a compound, the polymer is likely to be linear, and the heat resistance is also improved.

  In the present invention, the softening point of the amine adduct is preferably 0 ° C. or higher. Furthermore, the softening point temperature is preferably in the range of 40 to 150 ° C. When the softening point temperature is low, the surface adhesive force of the fiber bundle increases, and the subsequent process passability decreases. On the other hand, even if the softening point temperature is too high, the treated fiber bundle becomes hard, and even if polyurethane is used in combination, fluff is likely to occur and a problem in processability tends to occur. In addition, the draping property (texture) becomes too high and tends to adversely affect the production of the random mat. The softening point mentioned here is a temperature at which the thermoplastic resin can sufficiently flow, and can be measured by, for example, a softening point measuring device. In the case of a crystalline resin, the softening point is a temperature that is several degrees higher than the melting point. In the case of an amorphous resin, the softening point is a temperature that is 10 to 150 ° C. higher than the glass transition temperature depending on the molecular weight.

The amine adduct preferably has an ester bond or an ether bond, particularly an ester bond, and improves the adhesion of the treated fiber to the matrix resin.
Furthermore, in the present invention, it is preferable to form a water-soluble amine adduct by controlling the side chain and molecular structure as described later, or by devising a dissolution method.

  The high molecular weight amine adduct used in the present invention preferably has a 5% weight loss temperature in air of 250 ° C. or higher. Such an amine adduct having a 5% weight loss temperature in air of 250 ° C. or higher when the temperature is raised can be obtained by optimizing the structure of the epoxy resin and amine compound as raw materials. Furthermore, it is preferable that it is 280 degreeC or more. For example, a bifunctional low-molecular-weight alicyclic epoxy compound is reacted with a mixture of an amine compound having a saturated alicyclic hydrocarbon structure and an amine compound having an aliphatic structure, thereby reducing the weight during temperature rise. A linear polymer having a low degree and particularly suitable for the present invention can be obtained. When the 5% weight loss temperature is too low, especially when the matrix resin is impregnated at a high temperature, voids are generated during the impregnation process, and the composite physical properties tend to be deteriorated. On the other hand, a high molecular weight amine adduct having a high 5% weight loss temperature often includes a portion where the reaction product is three-dimensionally crosslinked, and thus tends to be gelled. Such amine adducts tend not to adhere to the surface of the fiber bundle. A more preferable range of the 5% weight loss temperature in the air of the amine adduct is 290 to 350 ° C., and particularly preferably 330 ° C. or less.

  The sizing agent-attached fiber bundle of the present invention is obtained by attaching a sizing agent containing an amine adduct and polyurethane as described above to the surface of a reinforcing fiber. Here, the weight blending ratio of the amine adduct and the polyurethane is preferably 1: 9 to 9: 1, and the value of (amine adduct: polyurethane) is 4: 6 to 9: 1, particularly 7: A range of 3-9: 1 is preferred.

Examples of the sizing agent containing polyurethane include, for example, a forced emulsification type trade name “Bondic” (manufactured by DIC Corporation, hydrophilic part: nonionic emulsifier), and a self-emulsification type trade name “Bondic 2200 series”. , "Hydran HW series", "Hydran AP series", "Hydran ADS", "Hydran CP series" (all manufactured by DIC Corporation, hydrophilic part is COOH group, SO ₃ Na group, nonion or cation), etc. Is preferably used.

In particular, when a fiber bundle in which the amine adduct of the present invention and polyurethane are attached is produced, the sizing agent-attached fiber bundle is optimal for manufacturing a random mat in which short fiber bundles are randomly oriented. This makes it easy to form a fiber bundle having a suitable drape (texture) and convergence. The reason for this is not clear, but it is thought that the amine adduct and polyurethane produce a moderately balanced texture. In particular, a random mat using such a sizing agent-attached fiber bundle has a specific ratio of an incompletely opened fiber bundle in which a specific number of reinforcing fibers are gathered and a fully opened fiber bundle. It is preferable to contain. In order to form such a form, it is important to adjust the drapability (texture) and convergence of the fiber bundle.
Moreover, in the fiber bundle of the present invention, by using such an amine adduct and polyurethane, it becomes possible to further improve the high-order processability of the finally obtained sizing agent-attached fiber bundle.

  The polyurethane used in the present invention is often used in a dispersion or emulsion sizing solution, and in that case, polyurethane particles larger than the gap diameter between the fibers constituting the fiber bundle and the fibers are between the fibers. There are many in the gap. Therefore, although the adhesion state tends to be different between the surface layer portion and the inner layer portion of the fiber bundle, it plays a role of increasing the convergence of the sizing agent-attached fiber bundle and ensuring good process handling properties.

  On the other hand, amine adducts are often used in sizing treatment liquids as water-soluble polymers dissolved in water. In this case, unlike polyurethane emulsion, it can be uniformly attached to the fiber bundle. At that time, it tends to be difficult to ensure the convergence of the fiber bundle, but in the present invention, the problem is solved by using the polyurethane emulsion together, and good process handling properties (convergence of reinforcing fibers) and uniform sizing are achieved. It became possible to achieve both agent adhesion.

  Moreover, when an amine adduct is dissolved in water, it has many polar groups such as hydroxyl groups and carboxylic acids in the molecular structure. The sizing agent-attached fiber bundle obtained by sizing such a water-soluble amine adduct adheres to the surface of the metal such as a roller with a polar force and a hydrogen bonding force, thereby increasing the take-up friction resistance of the fiber bundle. Tend to. When only the amine adduct is used, the take-up frictional resistance tends to increase because the amine adduct easily wets and spreads on a metal surface such as a roller. However, when a polyurethane emulsion is mixed with a part of such a sizing agent, surprisingly, the take-up frictional resistance of the fiber bundle can be rapidly reduced. Thus, the occurrence of scum in the process can be greatly suppressed. The reason for this is not clear, but it is probably due to the fact that the polyurethane emulsion diluted the number of polar groups in the solid content of the treatment liquid, increased the viscosity of the solid content, and suppressed wetting and spreading to the metal surface. Is done.

  The fiber bundle of the present invention is subjected to a widening and opening process on a metal roll, and then subjected to a random mat production process. At that time, the adhesiveness to the metal roll is lowered, and the process passability is remarkably improved. is there. Further, since the adhesiveness was reduced, it was possible to sufficiently suppress the occurrence of fluff and scum in the fiber bundle, and the physical properties of the composite material composed of the final sizing agent-attached fiber bundle and the matrix resin were also improved.

The present invention includes the invention of a fiber treatment liquid used for the sizing agent-attached fiber bundle of the present invention and a composite material comprising the sizing agent-attached fiber bundle of the present invention and a matrix resin.
Such a sizing agent-attached fiber bundle of the present invention is a fiber bundle when the sizing agent attached to the surface of the fiber bundle is melt-softened by heat and finally becomes a composite material composed of a fiber bundle and a matrix resin. The bundle collapses and separates, and the matrix resin impregnates the inner layer of the fiber bundle, and the sizing agent attached to the reinforcing fibers is entangled with the matrix resin at the molecular level, thereby realizing strong interface adhesion. In this way, the composite material using the sizing agent-attached fiber bundle of the present invention finally has good composite properties.

  Such a sizing agent-attached fiber bundle of the present invention can be obtained by another method of manufacturing a sizing agent-attached fiber bundle of the present invention. More specifically, the production method of the sizing agent-attached fiber bundle of the present invention will be described. The fiber bundle composed of reinforcing fibers contains an amine adduct, which is a reaction product of an epoxy compound and an amine compound, and a polyurethane emulsion. This is a method for producing a sizing agent-attached fiber bundle in which a treatment liquid is attached and dried.

As the fiber bundle composed of the reinforcing fibers used here, those used for the above-described sizing agent-attached fiber bundle of the present invention can be used.
Specific examples of such reinforcing fibers include various inorganic fibers and various organic fibers. Among them, carbon fibers, glass fibers, and aromatic polyamide fibers are preferable, and specific strength and specific elastic modulus are particularly good. The polyacrylonitrile (PAN) -based carbon fiber from which a lightweight and high-strength fiber-reinforced composite material can be obtained is preferable.

  Among these, when a high-viscosity thermoplastic resin is used for the matrix of the composite material, it is preferable to use a sizing agent having high surface free energy in order to wet and spread the thermoplastic resin on the surface of the sizing agent-attached fiber bundle. From such a viewpoint, the sizing agent preferably has at least one bond selected from an amide bond, a urethane bond and an ester bond in its molecular skeleton as a repeating unit. Furthermore, it is more preferable that the repeating unit has at least two bonds selected from amide bonds, urethane bonds, and ester bonds. For this reason, the sizing agent used in the present invention is an amine adduct which is a reaction product of an epoxy compound and an amine compound, together with various polyurethane resins such as polyester polyurethane, polyether polyurethane, polycarbonate polyurethane and polyether polyester polyurethane. It is more preferable to use an amine adduct salt obtained by neutralizing such an amine adduct with carbonic acid, acetic acid or the like.

  A preferred embodiment of the sizing agent used in the present invention is to immerse the fiber bundle in a sizing treatment solution containing an amine adduct and a polyurethane dispersion or emulsion, and then remove a solvent such as water. Here, the treatment liquid for reinforcing fibers preferably used in the present invention is a treatment liquid containing an amine adduct, which is a reaction product of an epoxy compound and an amine compound, and a polyurethane emulsion.

  In such a method of the present invention, since there are polyurethane particles larger than the gap diameter between the fibers constituting the fiber bundle, the particles are unevenly distributed in the gap between the fibers, and the sizing agent-attached fiber bundle Convergence can be increased and good process handling can be ensured. On the other hand, in the present invention, the amine adduct simultaneously dissolved in water is used for the sizing treatment solution, so that unlike the polyurethane particles, the sizing agent can be uniformly attached to the fiber bundle. In the sizing agent used in the present invention, it is possible to achieve both good process handling properties (convergence of reinforcing fibers) and uniform sizing agent adhesion.

As a mixing ratio of polyurethane and amine adduct, it is preferable to add polyurethane in a range of 10 to 90 wt% when the total mixing weight is 100 wt%. Furthermore, it is 10-60 wt%, More preferably, it is the range of 10-30 wt%.
In the method for producing a sizing agent-attached fiber bundle of the present invention, the treatment liquid as described above is attached to the fiber bundle and dried. The treatment liquid is preferably an aqueous solution as described above, and excess water and solvent in the aqueous solution are removed in the drying step.

  The most common method of applying the treatment liquid is to immerse the fiber bundle in the treatment liquid. The method for removing moisture and solvent from the fiber bundle is not limited. In the drying treatment of the present invention, various means such as heat treatment, air drying, and centrifugation may be used in combination. Heat treatment is preferable from the viewpoint of cost, and as a heating means for heat treatment, for example, hot air, a hot plate, a roller, an infrared heater or the like can be used. The temperature of the heat treatment (drying treatment) is preferably adjusted so that the surface temperature of the fiber bundle is in the range of 50 to 250 ° C., and the solvent is removed. Moreover, it is also preferable to raise the temperature of this heat treatment stepwise between 50 to 250 ° C., which enables more uniform drying. Moreover, various components, such as surfactant which inhibits adhesion | attachment with a reinforced fiber and a matrix, can be removed by processing at 100 degreeC or more high temperature. However, when the treatment temperature is too high, the sizing agent and thus the fiber bundle tends to deteriorate.

  Moreover, in the manufacturing method of the sizing agent adhesion fiber bundle of this invention, it is possible to apply | coat a process liquid on the conditions similar to a normal sizing liquid. At this time, the adhesion amount of the treatment liquid to the fiber is preferably 0.01% by weight or more and less than 3% by weight in terms of dry solid content. A more preferable range is 0.1% by weight or more and less than 2.0% by weight, and particularly preferably 0.15% by weight or more and less than 1.5% by weight. The solid weight of the treatment liquid referred to here is the total of all non-volatile trace components in addition to the polymer remaining after removing the solvent from the fiber bundle immersed in the treatment liquid. The proportion of the polymer in the solid content of the treatment liquid is preferably in the range of 10% to 100% by weight, more preferably 50% to 100% by weight. When the amount of treatment liquid attached is too small, the surface adhesiveness between the matrix and the reinforcing fibers is likely to be lowered when a composite material is finally obtained using a thermoplastic resin (thermoplastic polymer) as a matrix. The mechanical properties of composite materials tend to be low. On the other hand, when the amount of the treatment liquid attached is too large, the adhesion between the matrix and the reinforcing fiber tends to be reduced due to the precipitation of a small amount of the surfactant in the treatment liquid.

  The sizing agent-attached fiber bundle of the present invention can uniformly attach a polymer having a relatively large surface tension to the fiber surface, particularly when a reinforcing fiber having a large surface free energy is used. As a result, a sizing agent-attached fiber bundle having both drape (texture) and convergence suitable for manufacturing a random mat is obtained. In addition, the bundle shape of the fiber bundle that is difficult to impregnate in the molding process can be collapsed and divided to facilitate matrix impregnation in the fiber bundle thickness direction. Since the sizing agent used in the present invention has good heat resistance, it is difficult for decomposition gas to be generated in the heat impregnation step for producing the composite material, and a composite material having good mechanical properties can be obtained.

By such a method for producing a sizing agent-attached fiber bundle of the present invention, the sizing agent-attached fiber bundle of the present invention can be obtained. The sizing agent-attached fiber bundle of the present invention is optimal for a fiber / resin composite when used with a matrix resin.
Furthermore, the sizing agent-attached fiber bundle of the present invention is suitably used for a random mat in which the fiber bundles are oriented in random directions.
Furthermore, the random mat in which the sizing agent-attached fiber bundle of the present invention is randomly oriented forms a composite material having excellent strength by being combined with a matrix resin. These random mats and composite materials contain the sizing agent-attached fiber bundle of the present invention, and the matrix resin is preferably a thermoplastic polymer.

Here, the random mat is one in which reinforcing fibers are not oriented in a specific direction and are dispersed in a random direction within the mat surface. The term “in the mat surface” means a plane that is the width and length directions, and is different from the three-dimensional direction including the thickness direction. In general, when a mat shape is used, fibers having a certain length are parallel to a plane, and random orientation is difficult to obtain. In the present invention, the random orientation of the reinforcing fibers in the mat surface is important. The random mat may include a matrix resin in addition to the form made of only reinforcing fibers. And when taking the fiber form of a random mat, it is preferable that the fiber length of the fiber bundle is a discontinuous fiber bundle of ² to 100 mm, and the basis weight of the fibers constituting the random mat is 25 to 10,000 g / m ^2. Is preferred. Furthermore, it is preferable that the fiber length is a discontinuous fiber bundle of 3 to 60 mm and the basis weight is 25 to 3000 g / m ² .

  Thus, in order to arrange reinforcing fibers for reinforcement at random, it is preferable that the fiber bundle to be used is one that has been once appropriately opened. The random mat may be composed only of fiber bundles, but is composed of a fiber bundle that has been opened and cut into short fibers and a resin, preferably a thermoplastic resin, and the reinforcing fibers are substantially It is preferable that they are randomly oriented in the plane. Alternatively, it is possible to use a reinforcing fiber that has been completely opened into a single fiber state, but it is preferable that the fiber bundle state remains on the surface.

Such a random mat having the sizing agent-attached fiber bundle of the present invention as a constituent element is optimally used as a reinforcing material for composite materials. Furthermore, it is also preferable to use various reinforcing fiber forms such as uniaxially oriented fibers and woven fabrics as a reinforcing material for the composite material together with the random mat.
Random mat is a random mat that controls the degree of fiber bundle opening and contains a certain percentage of incompletely opened fiber bundles with sufficient number of reinforcing fibers and fully opened fibers. A mat is preferred. In some cases, it is also possible to use reinforcing fibers that have been completely opened into single fibers. In the present invention, by producing a random mat having an appropriate spread rate, the reinforcing fibers and the thermoplastic resin can be closely adhered to each other, and high physical properties can be achieved.

  Another composite material of the present invention comprises a reinforcing fiber obtained from the sizing agent-attached fiber bundle of the present invention and a matrix resin. Here, the reinforcing fiber obtained from the sizing agent-attached fiber bundle refers to reinforcing fibers of various forms obtained by processing the sizing agent-attached fiber bundle. It includes fibers and reinforcing fibers in the form of strands that have been incompletely opened. The fiber constituting the composite material may be only a reinforcing fiber that has become a single fiber, or conversely, may be composed of only a reinforcing fiber in a fiber bundle state. It is preferable to remain in this state.

  Here, the content of the reinforcing fiber in the composite material is preferably in the range of 10 to 60% by volume. Such a composite material containing the sizing agent-attached fiber bundle of the present invention is sufficiently high-impregnated with the matrix resin to be composited, and has less unevenness in strength. The composite material containing such reinforcing fibers may contain various additives as long as the object of the present invention is not impaired. In addition to the reinforcing fibers, other reinforcing fiber single yarns and one or more types of thermoplastic resins can be cited.

  The matrix resin used in the composite material of the present invention is not limited, but is preferably a resin made of a thermoplastic polymer, particularly preferably a polyamide resin, a polyester resin, an acid-modified polypropylene resin, or a polycarbonate resin. .

  In addition, as matrix resin used for the composite material of this invention, it is preferable that the surface free energy in 250 degreeC of the matrix resin is 35 mN / m or less. When the surface free energy of the matrix resin is too large, the matrix resin cannot sufficiently wet and spread on the surface of the fiber bundle covered with the reinforcing fiber or the sizing agent, and tends to melt and aggregate. When the matrix resin melts and aggregates, the interfacial adhesion and composite physical properties of the composite material are degraded. Further, the surface free energy of the matrix resin is preferably smaller than the surface free energy of the reinforcing fibers and the sizing agent. The molding temperature of the composite material is generally 300 ° C. at most, while the surface free energy of the matrix resin reaches approximately equilibrium at 250 ° C. or higher. That is, by defining the physical properties of the matrix resin at a temperature of 250 ° C., an appropriate composite material can be obtained. In the composite material of the present invention, the surface free energy at 250 ° C. of the matrix resin is more preferably in the range of 24 to 34 mN / m, and particularly preferably in the range of 26 to 33 mN / m. The matrix resin in such a range is preferably a polyamide resin, for example.

  Moreover, as described above, the surface tension of the amine adduct, which is the main component contained in the sizing agent attached to the surface of the sizing agent-attached fiber bundle used in the composite material of the present invention, is preferably 25 mN / m or more. In the composite material of the present invention, the absolute value of the surface free energy difference between the sizing agent component and the matrix resin at the molding temperature is preferably 6 mN / m or less. A more preferable range of the absolute value of the surface free energy difference is 3 mN / m or less, and further 2 mN / m or less.

  Further, the surface free energy of the sizing agent main component at the molding temperature is preferably larger than the surface free energy of the matrix resin. In this case, the matrix resin of the composite material can spread out in a short time on the surface of the reinforcing fiber coated with the sizing agent. Even when the sizing agent reacts with the matrix resin, the surface free energy of the sizing agent component is preferably larger than the surface free energy of the matrix resin. In this case, the absolute value of the surface free energy difference between the sizing agent and the matrix resin does not have much influence.

  Moreover, in addition to the short fiber bundle cut | disconnected for said random mat, the uniaxially oriented material of a long fiber state is used together for the composite material comprised from the sizing agent adhesion fiber bundle and matrix resin of this invention. You can also Here, the uniaxially oriented material can be obtained by bringing a uniaxially oriented reinforcing fiber bundle (sizing agent-attached fiber bundle) into contact with a melt-softened thermoplastic resin.

  The composite material may contain various additives such as an inorganic filler as long as the object of the present invention is not impaired. Examples of the inorganic filler include talc, calcium silicate, wollastonite, montmorillonite, and various inorganic nanofillers. In addition, as required, heat stabilizers, antistatic agents, weathering stabilizers, light stabilizers, anti-aging agents, antioxidants, softeners, dispersants, fillers, colorants, lubricants, etc. Other additives blended in the resin can also be blended. Moreover, it is also preferable to use together various reinforcing fiber single yarns and one or more types of thermoplastic resins as constituent components other than the sizing agent-attached fiber bundle of the present invention.

  Such a composite material can ensure high physical properties due to the presence of a sizing agent present between the fiber and the matrix resin. This composite material has high adhesion between the reinforcing fiber obtained from the sizing agent-attached fiber bundle of the present invention and the matrix resin, so that it is lightweight, but it has strength characteristics, in particular bending strength and bending elastic modulus. It becomes a composite material with excellent properties. The composite material of the present invention is optimally used in various fields such as office equipment use, automobile use, computer use (IC tray, notebook computer housing (housing), etc.).

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, the following Example does not restrict | limit this invention. In addition, the Example of this invention was evaluated by the method shown below.

(1) Extraction of solid content from sizing treatment liquid and emulsion After removing moisture from the sizing treatment liquid and emulsion under conditions of a hot air dryer at 120 ° C. for 5 hours, a vacuum drier (−0. The solid content was extracted from the sizing treatment liquid or emulsion by performing dehydration treatment at 1 MPa for 2 hours.

(2) Measuring method of 5% weight reduction temperature The 5% weight reduction temperature of the solid content of the above (1) extracted from the sizing treatment liquid and the emulsion is obtained by using a differential thermogravimetric measuring device (TGA) manufactured by Seiko Electronics Co., Ltd. A 10 mg sample was calculated from the weight loss curve when the temperature was raised to 400 ° C. at 10 ° C./min under air flow at 50 mL / min.

(3) Evaluation of softening point of amine adduct The softening point of the amine adduct was evaluated using a softening point measuring device (FP-90) manufactured by METTLER TOLEDO CO., LTD.

(4) Measurement of surface tension of solids extracted from sizing treatment liquid and emulsion A solid contact or matrix resin melted at 250 ° C. or 260 ° C. was subjected to an automatic contact angle meter (DM-501) manufactured by Kyowa Interface Science. ) And the surface tension was measured by the hanging drop method. The surface tension was obtained from the average of measured values obtained from three hanging drops.

(5) Impregnation evaluation of treatment liquid A treatment liquid (aqueous solution) containing an amine adduct was placed from the bottom of a glass container to a height of 5 cm. Fiber bundle before processing cut to 1 cm in the fiber direction (unsized flat carbon fiber bundle, manufactured by Toho Tenax Co., Ltd., “Tenax STS-24K N00”, diameter 7 μm × 24000 filament, width 16 mm, thickness 142 μm) And the wetness of the surface of the fiber bundle after landing and the time until the fiber bundle sinks to the bottom of the glass container were measured and evaluated as the impregnation property of the treatment liquid.

(6) Evaluation of treatment liquid adhesion amount The treatment liquid solid adhesion amount was obtained by collecting two treated 1.0 m sizing agent-attached fiber bundles (carbon fiber bundles) and treating them at 10 ° C. in a nitrogen atmosphere. The temperature was raised to 550 ° C./min and then baked at the same temperature for 10 minutes, and the weight decreased was calculated by the following formula (1) as the solid content adhesion amount of the treatment liquid.
Solid content of treatment liquid = (ab) / b × 100 [%] (1)
a: Weight of fiber bundle before firing process [g]
b: Weight of fiber bundle after firing treatment [g]

(7) Measurement of surface adhesive strength of fiber bundle The surface adhesive strength of the fiber bundle was measured by the following method using a tacking test apparatus TAC-II (manufactured by RHESCA CO., LTD.). As a test method, a fiber bundle was set on a test stage held at 120 ° C., an initial load of 400 gf was applied with a φ10 tack probe held at 120 ° C., a pressing speed of 0.5 mm / second, and a holding time of 10 Second, the maximum load when pulled out at a test speed of 5 mm / second was determined.

(8) Method for measuring bending physical properties of reinforcing fiber composite material A test piece having a width of 15 mm and a length of 100 mm is cut out from a composite material (molded plate) made of a reinforcing fiber bundle (sizing agent-attached fiber bundle) and a matrix resin, and JIS K7074 The physical properties were evaluated by three-point bending with a compliant center load. Maximum load and center deflection when a test piece is placed on a fulcrum of r = 2mm with a fulcrum distance of 80mm and a load is applied at a test speed of 5mm / min with an indenter of r = 5mm in the center between the fulcrum The bending strength and the bending elastic modulus were measured.

[Example 1]
<Manufacture of amine adduct>
As the epoxy compound, 3 ′, 4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (manufactured by Daicel Corporation, Celoxide “CEL-2021P”) is used, and amine-terminated polypropylene glycol (manufactured by HUNTSMAN, "JEFFAMINE D230") was used. 30.0 parts by weight of the aforementioned epoxy compound. An amine adduct was obtained by mixing 35.9 parts by weight of the amine compound and then reacting at 160 ° C. with stirring for 2 hours.
On the other hand, the surface tension of this amine adduct at 250 ° C. was 29 mN / m, the 5% weight loss temperature was as low as 252 ° C., and the softening point temperature was as low as 6 ° C.

<Creation of processing solution>
80 parts by weight of an amine adduct pulverized by a pulverizer was dropped dropwise into 1000 parts by weight of carbonated water while stirring to prepare a lemon-colored transparent solution. Next, after diluting 200 parts by weight of a polyester urethane emulsion (solid content concentration 10 wt%) with 820 parts by weight of distilled water, the whole amount of the amine adduct aqueous solution is added with stirring, so that the mixture of the water-soluble polymer and the emulsion is removed. A sizing treatment solution was obtained. When the impregnation of the treatment liquid was evaluated, the fiber bundle surface was immediately wetted and settled to the bottom of a 5 cm glass container in about 4 seconds, and the treatment liquid was immersed very well in the fiber bundle. I confirmed that there was.

<Manufacture of sizing agent-attached fiber bundle>
Next, the untreated fiber bundle before cutting (carbon fiber bundle, manufactured by Toho Tenax Co., Ltd., “Tenax STS-24K N00”) used in the immersion test was continuously immersed in the bath of the treatment liquid. And the treatment solution was infiltrated between the filaments in the fiber bundle. This was dried to obtain a sizing agent-attached fiber bundle. The amount of solid content of the treatment liquid in the obtained fiber bundle was 1.0 part by weight with respect to 100 parts by weight of the reinforcing fiber, and the sizing agent-attached fiber bundle had an appropriate feel and convergence. It was a thing. Also, the surface adhesive strength at 120 ° C. is as low as 16.6 gf, and the scum was melted and softened in a one-hour continuous test with low frictional resistance when thermally expanded with a fixed metal bar at the same temperature. No resin puddle was observed. In addition, the abrasion resistance of the fiber bundle was good, and the occurrence of surface fluff in the continuous test was very small.

<Manufacture of composite materials>
Cut the above sizing agent-attached fiber bundle, prepare a matrix thermoplastic resin (nylon 6 resin powder), spread the fiber bundle, fix it, and open the fiber bundle and the single yarn properly opened. A random mat (fiber resin composition) randomly oriented inside was obtained.
The obtained random mat was pressed to obtain a composite material (fiber reinforced thermoplastic resin molding). The obtained composite material had a surface appearance in which fiber bundles and single yarns were appropriately dispersed. The surface tension of amine adduct and nylon 6 resin powder at a molding temperature of 260 ° C. is 31 mN / m and 32 mN / m, respectively, and the absolute value of the difference in surface tension between amine adduct and nylon 6 resin powder is 1 mN / m. there were. In the obtained composite material, some unimpregnated parts that were considered to be cracked gases were observed. On the other hand, the amine adduct has good compatibility with the matrix resin, and its bending properties are as high as a bending strength of 487 MPa and a bending elastic modulus of 23 GPa.

[Example 2]
<Manufacture of amine adduct>
Alicyclic bifunctional epoxy compound heated to 120 ° C. (3 ′, 4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (Daicel Corporation, Celoxide “CEL-2021P”, molecular weight 252.3) In 3 parts by weight, 90.3 parts by weight of isophoronediamine (3-aminomethyl-3,5,5-trimethylcyclohexylamine, molecular weight 170.3) which is an alicyclic bifunctional amine compound as an amine compound and aliphatic 2 A mixture of 76.0 parts by weight of a functional amine compound (N, N′-di (2-aminoethyl) ethylenediamine, molecular weight 146.2) was dropped over 25 minutes using a dropping funnel, and the mixture was further stirred for 100 minutes. On the other hand, the surface tension of this amine adduct at 250 ° C. was 30 mN / m, 5% weight. Loss temperature as high as 303 ° C., a softening point temperature was 51 ° C..

<Creation of processing solution>
80 parts by weight of an amine adduct pulverized by a pulverizer was dropped dropwise into 1000 parts by weight of carbonated water while stirring to prepare a lemon-colored transparent solution. Next, after diluting 200 parts by weight of a polyester urethane emulsion (solid content concentration 10 wt%) with 820 parts by weight of distilled water, the whole amount of the amine adduct aqueous solution is added with stirring, so that the mixture of the water-soluble polymer and the emulsion is removed. A sizing treatment solution was obtained. When the impregnation of the treatment liquid was evaluated, the fiber bundle surface was immediately wetted and settled to the bottom of a 5 cm glass container in about 4 seconds, and the treatment liquid was immersed very well in the fiber bundle. I confirmed that there was.

<Manufacture of sizing agent-attached fiber bundle>
Next, the untreated fiber bundle before cutting (carbon fiber bundle, manufactured by Toho Tenax Co., Ltd., “Tenax STS-24K N00”) used in the immersion test was continuously immersed in the bath of the treatment liquid. And the treatment solution was infiltrated between the filaments in the fiber bundle. This was dried to obtain a sizing agent-attached fiber bundle. The amount of solid content of the treatment liquid in the obtained fiber bundle was 0.9 parts by weight with respect to 100 parts by weight of the reinforcing fiber, and the sizing agent-attached fiber bundle had an appropriate feel and convergence. It was a thing. In addition, the surface adhesive strength at 120 ° C. is a low value of 9.6 gf, and when the heat is widened with a fixed metal bar at the same temperature, the frictional resistance with the metal surface is small, and the scum melted and softened in a one-hour continuous test. No resin reservoir was observed. In addition, the abrasion resistance of the fiber bundle was good, and the occurrence of surface fluff in the continuous test was very small.

<Manufacture of composite materials>
Cut the above sizing agent-attached fiber bundle, prepare a thermoplastic resin (nylon 6 resin powder) as a matrix, spread the fiber bundle, fix it, and the fiber bundle and single yarn that have been properly opened in war are in the plane A randomly oriented random mat (fiber resin composition) was obtained.
The obtained random mat was pressed to obtain a composite material (fiber reinforced thermoplastic resin molding). The obtained composite material had a surface appearance in which fiber bundles and single yarns were appropriately dispersed. The surface tension of amine adduct and nylon 6 resin powder at a molding temperature of 260 ° C. is 29 mN / m and 32 mN / m, respectively, and the absolute value of the difference in surface tension between amine adduct and nylon 6 resin powder is 3 mN / m. there were. There was no unimpregnated part in the obtained composite material. In addition, the amine adduct had good compatibility with the matrix resin, and the bending properties were as high as a bending strength of 514 MPa and a bending elastic modulus of 26 GPa.

[Comparative Example 1]
<Creation of processing solution>
50 parts by weight of the epoxy-amine adduct of Example 1 pulverized by a pulverizer was gradually added to 1000 parts by weight of carbonated water with stirring to prepare a lemon-colored transparent solution. This aqueous solution was used as a processing solution for sizing. In addition, when the impregnation property of the treatment liquid was evaluated, the fiber bundle surface was immediately wetted and settled on the bottom of a 5 cm glass container in about 5 seconds, and the immersion property of the treatment liquid into the fiber bundle was very good. I confirmed that there was.

<Manufacture of sizing agent-attached fiber bundle>
Next, the untreated fiber bundle before cutting (carbon fiber bundle, manufactured by Toho Tenax Co., Ltd., “Tenax STS-24K N00”) used in the immersion test was continuously immersed in the bath of the treatment liquid. And the treatment solution was infiltrated between the filaments in the fiber bundle. This was dried to obtain a sizing agent-attached fiber bundle. The solid content of the treatment liquid in the obtained fiber bundle was 1.2 parts by weight with respect to 100 parts by weight of the reinforcing fiber, and the feel and convergence of the fiber bundle were very low. In addition, the surface adhesive strength at 120 ° C. is 46 gf, which is higher than that of Example 1, and when thermally expanding with a fixed metal bar at the same temperature, the frictional resistance with the metal surface is large, and it melts in a continuous test for 1 hour. A softened scum-like resin reservoir was observed. Furthermore, the fiber bundles were not easily scratched, and surface fluff was generated in the continuous test.
Further, the opening rate of this fiber bundle was particularly high, and many single yarns appeared and were bulky.

<Manufacture of composite materials>
The above sizing agent-attached fiber bundle was cut to 20 mm, a thermoplastic resin (nylon 6 resin powder) serving as a matrix was prepared, the fiber bundle was sprayed, and the reinforcing fiber and the thermoplastic resin powder were fixed. The sizing agent-attached fiber bundle and single yarn became a random mat (fiber resin composition) that was randomly oriented not only in the plane but also in the thickness direction.
The obtained random mat was pressed to obtain a composite material (fiber reinforced thermoplastic resin molding). The resulting composite material had a surface appearance with very much single yarn. The surface tensions of the linear polymer and the nylon 6 resin powder at the molding temperature are 30 mN / m and 28 mN / m, respectively, and the absolute value of the surface tension difference between the epoxy-amine adduct and the nylon 6 resin powder is 2 mN / m. m. In the obtained composite material, the random mat was bulky, and unimpregnated portions were observed in some places. The bending physical properties of the composite material were particularly low physical properties such as a bending strength of 325 MPa and a bending elastic modulus of 15 GPa.

Claims (6)

A fiber bundle having a sizing agent attached to its surface, the entire shape of the fiber bundle being a flat fiber bundle, the thickness of the fiber bundle being 200 μm or less, and an amine in which the sizing agent is a reaction product of an epoxy compound and an amine compound A sizing agent-attached fiber bundle comprising an amine adduct salt neutralized with an adduct and polyurethane.   The sizing-agent-attached fiber bundle according to claim 1, wherein the weight blending ratio of the amine adduct and the polyurethane is 1: 9 to 9: 1.   The sizing agent-attached fiber bundle according to claim 1 or 2, wherein the fiber bundle is a carbon fiber bundle. A fiber bundle composed of reinforcing fibers , the overall shape of the fiber bundle is a flat fiber bundle, the thickness of the fiber bundle is 200 μm or less, and a reaction product of an epoxy compound and an amine compound is formed on the surface of the fiber bundle. A method for producing a bundle of sizing agent-attached fibers, wherein a treatment liquid containing an amine adduct salt neutralized with an amine adduct and a polyurethane emulsion is attached and dried.   The composite material which consists of a reinforced fiber and matrix resin obtained from the sizing agent adhesion fiber bundle of any one of Claims 1-3. 6. The composite material according to claim 5, wherein the sizing agent-attached fiber bundle is a discontinuous fiber bundle and is a random mat oriented in a random direction.