JPH10231372A - Prepreg and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a prepreg having good tack with little deterioration with the lapse of time, and capable of giving a fiber-reinforced composite material excellent in compressive interlaminer shear strength(CILS) and a cross laminate compressive strength(LCS) at a high temperature after moisture absorption while keeping its impact resistance. SOLUTION: This prepreg is produced by impregnating a resin satisfying a requirement (B) in carbon fiber satisfying a requirement (A). In this prepreg, particles satisfying a requirement (C) exist not more than 20%, and they are distributed on the surface in higher concentration than inside the prepreg. Requirement (A): Carbon fiber with a tensile strength not less than 4,400MPa consisting of continuous fiber having a hook-drop value not less than 10cm. Requirement (B): A base resin consisting mainly of a thermosetting resin. Requirement (C): Particles with each size not more than 150μm consisting of a thermoplastic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composite obtained by impregnating a carbon fiber with a thermosetting resin suitable as a matrix resin for a fiber-reinforced composite material, particularly having excellent impact resistance and high compressive strength of a cross-laminate. And a method for producing the same.

[0002]

2. Description of the Related Art Fiber-reinforced composite materials using a thermosetting resin as a matrix are lightweight and have excellent mechanical properties, corrosion resistance, etc., and have been used in industrial fields such as aerospace, sports, civil engineering and construction. It has been widely used, and prepregs and composite materials using combinations of various thermosetting resins and reinforcing fibers have been known. Among them, a prepreg made of an epoxy resin and carbon fiber is excellent in specific strength and specific elastic modulus, and is excellent in various properties such as heat resistance and compressive strength as a composite material.

[0003] A prepreg is obtained by impregnating a matrix resin made of an epoxy resin or the like with a reinforcing fiber such as a carbon fiber, and can be manufactured by several methods. Generally, a resin coating film in which a matrix resin is coated on a film such as release paper and a reinforcing fiber sheet in which reinforcing fibers such as carbon fibers are arranged in a sheet shape are used, and both sides of the reinforcing fiber sheet or The resin side of the resin coating film is superimposed on one side, and the resin is impregnated between the reinforcing fibers by heating and pressurizing the resin side, thereby producing a prepreg.

[0004] In general, a composite material using a thermosetting resin as a matrix resin is brittle and is vulnerable to impact.

For some applications, prepregs having improved impact resistance are required. For example, Japanese Patent Application Laid-Open No. 1-104624 discloses a method in which thermoplastic particles are disposed on a prepreg surface layer, and as a result, when prepregs are laminated, A so-called grain-layer reinforced prepreg in which high-toughness thermoplastic particles are localized between the laminated layers is disclosed.

However, in this technique, impact resistance is greatly improved, but CILS (Compression Interlaminer) is used.
Shear Strength:
There are limitations on application to applications requiring compressive interlaminar shear strength. In addition, the prepreg strengthened between layers of particles generally has a disadvantage that the tack described later is weaker than the prepreg containing no particles.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a prepreg having a good prepreg tack and a small change in tack with time. Another object of the present invention is to provide a prepreg that enables formation of a fiber-reinforced composite material having excellent CILS at a high temperature after moisture absorption while maintaining impact resistance. Furthermore, the compressive strength (LCS: Laminate Compres
sive strength) provides a prepreg that is significantly higher than existing materials.

[0008]

According to the present invention, there is provided a prepreg comprising:
In order to achieve the above object, the following configuration is provided.

That is, in a prepreg obtained by impregnating a resin of the requirement [B] into a carbon fiber satisfying the requirement [A], particles satisfying the requirement [C] are present in the prepreg in an amount of 20% by weight or less. A prepreg characterized by being distributed at a higher concentration on the surface than on the inside.

[A]: carbon fiber composed of continuous fibers having a hook drop value of 10 cm or more [B]: base resin composed mainly of a thermosetting resin [C]: particle diameter of 150 μm or less composed of a thermoplastic resin Particles.

Further, the method for producing a prepreg according to the present invention comprises:
To achieve the above object, the present invention has one of the following configurations. That is, (a) a sheet made of a number of continuous carbon filaments and a carbon fiber bundle having a fiber entanglement with a hook drop value of 10 cm or more is prepared, and (b) a thermosetting resin is prepared. A matrix resin formed by mixing a base resin as a main component and particles of a thermoplastic resin having a particle size of 150 μm or less in a weight of 20% or less of the weight of the completed prepreg was coated on a release film. A step of preparing a resin coating film; and (c) superimposing the resin coating film on the sheet of carbon fiber bundle in a state where the matrix resin is in contact with the surface of the sheet of carbon fiber bundle. A step of forming a laminated sheet; and (d) the laminated sheet is heated and pressurized to form a plurality of carbon fiber bundles. Between elementary filaments, the base resin is a resin-impregnated molded body is impregnated is a step to be formed, a method of manufacturing a prepreg comprising a capital, or
(A) a step of preparing a carbon fiber sheet composed of a number of continuous carbon filaments and a carbon fiber bundle having a fiber entanglement with a hook drop value of 10 cm or more; and (b) a thermosetting resin mainly. Is the first base resin
A step of preparing a first resin coating film coated on the release film of (c), and (c) coating the first resin coating film in a state where the base resin is in contact with the surface of the sheet made of the carbon fiber bundle. Forming a first laminated sheet in which a film is superimposed on a sheet made of the carbon fiber bundle; and (d) heating and pressing the first laminated sheet to form a first laminated sheet. Forming a first resin-impregnated molded body impregnated with the base resin between a number of carbon filaments;
(E) a matrix resin comprising a mixture of a base resin mainly composed of a thermosetting resin and particles of a thermoplastic resin having a particle size of 150 μm or less in a weight of 20% or less of the weight of the completed prepreg. A step of preparing a second resin coating film coated on a second release film; and (f) a matrix resin of the second resin coating film on a surface of the first resin impregnated molded body. A step of forming a second laminated sheet in which the second resin coating film is superimposed on the first resin-impregnated molded body so that the second laminated sheet is in contact with the second laminated sheet; (g) heating the second laminated sheet by heating; And a step of forming a second resin-impregnated molded body in which the matrix resin and the base resin are integrated with each other under pressure, thereby forming a prepreg. .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description, the name of a part consisting of both a constituent element [B] and a constituent element [C] will be referred to.
The name which is called a matrix resin and designates only the component [B] is used as a base resin, and these are distinguished from each other.

The component [B] of the present invention is a base resin mainly composed of a thermosetting resin as defined above.

Examples of the thermosetting resin include epoxy resin, unsaturated polyester resin, vinyl ester resin, phenol resin, urethane resin, urea resin, melamine resin, maleimide resin, cyanate ester resin, alkyd resin, and addition-curable polyimide resin. And the like. Among them, an epoxy resin is preferably used because a composite material having excellent heat resistance and mechanical properties can be obtained.

Epoxy resins include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol B epoxy resin, bisphenol S epoxy resin, naphthalene epoxy resin, novolak epoxy resin, epoxy resin having a fluorene skeleton, and phenol compound. Resin derived from copolymerization of dicyclopentadiene with diglycidyl resorcinol, glycidyl ether type epoxy resin such as tetrakis (glycidyloxyphenyl) ethane, tris (glycidyloxyphenyl) methane, tetraglycidylaminodiphenylmethane, triglycidylamino Cresol, glycidylamine type epoxy resins such as tetraglycidyl xylene diamine and mixtures thereof are used,
It is not limited to this.

The preferred epoxy resin is a mixture of a bifunctional or higher functional glycidylamine type epoxy resin and a bisphenol F type epoxy resin.

It is also preferable to mix and dissolve a thermoplastic resin with the thermosetting resin. As such a thermoplastic resin, generally, a carbon-carbon bond,
It has a bond selected from an amide bond, an imide bond, an ester bond, an ether bond, a carbonate bond, a urethane bond, a urea bond, a thioether bond, a sulfone bond, an imidazole bond, and a carbonyl bond.

In particular, it is preferable that at least one resin selected from polysulfone, polyethersulfone, polyetherimide and polyimide is mixed and dissolved in the component [B].

As these thermoplastic resins, commercially available polymers may be used, or so-called oligomers having a lower molecular weight than commercially available polymers may be used. As the oligomer, an oligomer having a functional group capable of reacting with the thermosetting resin at the terminal or in the molecular chain is more preferable.

A mixture of a thermosetting resin and a thermoplastic resin gives better results than when used alone. The brittleness of the thermosetting resin is covered by the toughness of the thermoplastic resin, and the molding difficulty of the thermoplastic resin is covered by the thermosetting resin, thereby providing a well-balanced base resin.

Examples of the curing agent include aromatic amines such as diaminodiphenylmethane and diaminodiphenylsulfone, aliphatic amines, imidazole derivatives, dicyandiamide, tetramethylguanidine, and thiourea-added amines.
Examples include, but are not limited to, methyl hexahydrophthalic anhydride, carboxylic acid amide, polyphenol compounds, novolak resins, polymer kapton, and Lewis acid complexes such as boron trifluoride ethylamine complex.

Diaminodiphenyl sulfone is preferably used as a curing agent for the epoxy resin of the component [B].

[0023] These curing agents may be combined with an appropriate curing aid in order to enhance the curing activity. As a preferred example, dicyandiamide has 3- (3-, 4-
Dichlorophenyl) -1,1-dimethylurea (DCM
There is an example in which U) is combined as a curing aid, and an example in which a tertiary amine is combined with a carboxylic anhydride or a novolak resin as a curing aid.

The constituent element [C] of the present invention is, as defined above, particles composed of a thermoplastic resin having a particle size of 150 μm or less.

For example, polyvinyl acetate, polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamide imide, polyimide, polyether imide, polysulfone, polyether sulfone, polyether ether ketone, polyaramid, poly Examples include particles having a particle size of 150 μm or less made of at least one resin selected from the group consisting of benzimidazole, polyethylene, polypropylene, cellulose acetate, and cellulose butyrate.

Preferably, the particles are made of at least one resin selected from the group consisting of polyamide, polyarylate, polyamideimide, polyimide, polyetherimide, polysulfone, polyethersulfone, and polyaramid, and have a particle diameter of 60 μm or less. .

A particularly preferred resin forming the particles is
It is a polyamide. Among them, polyamide mainly composed of nylon-12 is particularly excellent in terms of impact resistance. A specific example is SP-500 manufactured by Toray Industries, Inc.

When selecting the material of the component [C], it is preferable that the elastic modulus of the material of the component [C] is lower than the elastic modulus of the cured product of the component [B] to obtain a high LCS. In particular, the flexural modulus of the material of the component [C] is preferably 2/3 or less, more preferably 1/2 or less of the flexural modulus of the cured product of the component [B].

A semi-IPN (polymer interpenetrating network: Inter-pene) is formed by a combination of a polyamide resin and an epoxy resin as disclosed in JP-A-1-104624.
trating Polymer Network) or semi-IP
Particles capable of being N are more preferable because they have both heat resistance and solvent resistance. Specifically, Toray Industries, Inc.'s Trepearl (registered trademark) TN is exemplified.

These particles may be used alone or in combination of two or more.

The particle size of the particles means a volume average particle size determined by a centrifugal sedimentation velocity method or the like. The size of the particles when formed into a composite material need not be large enough to disrupt the arrangement of the reinforcing fibers.

When the particle size is 150 μm or more, the arrangement of the reinforcing fibers is disturbed or the layers of the composite material obtained by laminating are unnecessarily thick. Therefore, it must be 150 μm or less.

When the particle size is 1 μm or less, the particles penetrate between the reinforcing fibers, do not localize in the interlayer portion of the prepreg laminate, the effect of the particles cannot be sufficiently obtained, and the impact resistance is lowered. Therefore, the particle size is preferably 1 μm or more.

The more preferred particle size is 3 to 60 μm.
m, and more preferably 5 to 30 μm.

The external shape, surface or internal form of the particles may be spherical particles, non-spherical particles, or porous particles.

Although a spherical shape is preferred in that the flow characteristics of the resin are not deteriorated, the purpose of using particles of the thermoplastic resin having a specific particle size is to localize the particles between layers of the laminate. Therefore, the shape and form of the particles are not particularly limited.

It is essential that the particles be distributed at a higher concentration on one or both surfaces of the prepreg than on the inside. Here, “distributed at a higher concentration on the surface than on the inside” means that 90% or more of the particles are localized within 30% of the thickness of the prepreg from the surface of the prepreg. The degree of localization of the particles in the prepreg can be evaluated by the following method as disclosed in JP-A-1-104624. That is, first, the prepreg is brought into close contact with two smooth support plates, and is gradually hardened by gradually raising the temperature over a long period of time. What is important at this time is to gel at as low a temperature as possible. If the temperature is increased before gelation, the resin in the prepreg flows and the particles move, so that accurate evaluation of the particle distribution in the original prepreg cannot be performed. After the gelling, the prepreg is hardened by gradually increasing the temperature over time. The cross section of the cured prepreg is magnified 200 times or more and a photograph of 200 mm × 200 mm or more is taken. First, an average prepreg thickness is determined using this cross-sectional photograph. The average thickness of one layer of prepreg is measured at at least five locations arbitrarily selected on the photograph, and the average is taken. Next, a line is drawn parallel to both directions of the prepreg at a position 30% of the thickness of the prepreg from the surface in contact with both support plates. The cross-sectional area of the particles existing between the surface in contact with the support plate and the 30% parallel line is determined for both surfaces of the prepreg, and the cross-sectional area of the particles existing over the entire width of the prepreg is determined. The thickness of the prepreg from the prepreg surface to 3
The amount of particles present within 0% is calculated. The quantitative determination of the particle cross-sectional area may be performed by an image analyzer, or may be performed by cutting out all the particle portions present in a predetermined region from a cross-sectional photograph and weighing the same. In order to eliminate the influence of the partial distribution of particles, this evaluation was performed over the entire width of the obtained photograph, and the same evaluation was performed for five or more randomly selected photographs, and the average was calculated. Need to be taken. When it is difficult to distinguish the particles from the matrix resin, one of them is selectively dyed and observed. The microscope may be an optical microscope or a scanning electron microscope, and may be used properly depending on the size of the particles and the staining method.

As the amount of the particles, with respect to the prepreg,
It must be in the range of 20% by weight or less. If the content exceeds 20% by weight of the prepreg, mixing with the base resin becomes difficult, and the tack and drapability of the prepreg decrease. In order to impart impact resistance to the particles while maintaining the properties of the base resin, the amount of the particles needs to be 20% by weight or less based on the prepreg, and more preferably 15% by weight or less. is there. In order to further improve the handling of the prepreg, the amount of the particles is preferably 10% by weight or less. The amount of particles is preferably 1% by weight or more, and more preferably 2% by weight or more, based on the prepreg in order to obtain high impact resistance and cross-laminate compression strength.

The particle content in the prepreg is evaluated as follows. First, a solvent that dissolves the matrix resin but does not dissolve the particles is selected. The solvent is placed in a beaker and the weighed prepreg is immersed therein. After dissolving the resin using an ultrasonic cleaner, the reinforcing fibers are picked up with tweezers, and the remaining solution is filtered on a membrane filter whose weight has been measured in advance. Here, the particles are filtered off on the filter and the dissolved resin passes through the filter together with the solvent. Next, the reinforcing fiber picked up by the tweezers is returned to the original beaker. The operation of washing the reinforcing fibers with a solvent in a beaker and filtering the washing solution with a filter is repeated several times. After taking out the washed reinforcing fibers, the inner wall is washed several times with a solvent so that no particles remain in the beaker, and the washing solution is filtered. The filter from which the particles have been filtered is folded in four, dried in an oven, and weighed. The value obtained by subtracting the original filter weight is the particle weight, and the particle content can be calculated from the ratio to the original prepreg weight.

The particles of the constituent element [C] may remain in their shape or may be deformed after molding and curing into a composite material. Furthermore, the original shape may be completely lost, for example, by dissolving in the component [B] after molding and phase separation after dissolution.

The conventional interlayer reinforced prepreg has a disadvantage in that the impact resistance is greatly improved, but the CILS is reduced.

In particular, the decrease in CILS at a high temperature after moisture absorption was more remarkable.

CILS stands for BOEING MATERIAL SPECIFICAT
It can be evaluated by the method described in ION 8-276.

The CILS at a high temperature after moisture absorption means that a test piece processed to a specified size is 71 ± 5 ° C. (160 ± 5 ° C.).
10F) After immersion in warm water for 2 weeks, take out, 82.2
It is measured in an atmosphere of ± 5 ° C. (180 ± 10 F).

The impact resistance was measured by CAI (Compression Streng
th After Impact: compressive strength after impact), B
It can be evaluated by the method described in OEING MATERIAL SPECIFICATION 8-276.

The tackiness of the prepreg is good, the change with time is small, and the impact resistance and CILS of the laminate are improved.
In addition, as a result of diligent studies on means for improving the compressive strength (LCS) of the cross-laminate, the use of substantially twisted and untwisted carbon fiber of the component [A] as the reinforcing fiber, together with the component [C] Was found to be effective.

That is, although the presence of the particles of the constituent element [C] is indispensable for improving the impact resistance, the conventional technique in which the constituent element [C] is simply added reduces the CILS and the tackiness of the prepreg. Was accompanied. Therefore, as a result of intensive studies, it has been found that when carbon fibers that are substantially twisted and have no twist are used together with the constituent element [C], CI can be obtained without impairing impact resistance.
It has been found that the LS can be improved, the tackiness of the prepreg can be improved, and surprisingly, the LCS can be improved.

The constituent element [A] is a carbon fiber made of continuous fiber having a hook drop value of 10 cm or more as defined above. More preferable carbon fibers are those having a substantially circular cross section. The twist and twist of the carbon fiber can be quantitatively represented by a hook drop value.

Here, the hook drop value is measured in the following procedure. That is, temperature 23 ± 2 ° C., humidity 50 ± 5%
The carbon fiber bundle is left for 2 hours in the atmosphere described above. The carbon fiber bundle is cut to a length of 1.5 m, and a load of 100 g is applied to the lower part to suspend the fiber bundle vertically. 1mmφ, length 100m
The lower part of the stainless steel wire of about m is bent to 20-30 mm, and a load is applied so that the total weight becomes 12 g,
The upper part 20 to 30 mm is hooked at the center of the fiber bundle width direction at the part bent in a U-shape. The drop distance (unit, cm) of the load after a lapse of 30 minutes is defined as a hook drop value. Twist,
If there is a twist, this value decreases. Take at least 5 measurements and take the average.

In general, carbon fibers are used to prevent process troubles such as winding of broken filaments around a roller in the production process. In prepreg production, creels, guides, and combs for supplying carbon fibers are used to reduce carbon fiber. In order to suppress the spread and improve the process passability, convergence is provided.

As a method of bundling carbon fibers, there are a method of imparting entanglement, a method of imparting twist, and a method of imparting a sizing agent to the filaments of the fiber bundle. In addition,
When twist is applied, the twist may be released after passing through the process.

However, when the carbon fibers are bundled,
Although the processability is improved, the impregnating property of the matrix resin is reduced in the production of the prepreg due to its convergence. In the method of releasing after twisting, twisting and twisting remain in the carbon fiber, so that the produced prepreg is not smooth and has irregularities on the surface, which adversely affects the physical properties of the composite material. The index of the convergence is the hook drop value.

Increasing the hook drop value improves the resin impregnating property and surface smoothness in the production of prepreg. However, the creels, guides, and combs for supplying carbon fibers cause the carbon fiber bundle to spread too much, resulting in fluffing. Troubles such as poor passability are likely to occur.

From this point, the preferable hook drop value of the carbon fiber bundle is 10 cm or more and 100 cm or less, more preferably 12 cm or more and 100 cm or less.

As described above, it has been found that when carbon fibers having substantially no twist and no twist are used in combination with a matrix resin, CILS at a high temperature after moisture absorption is improved.

A prepreg using a carbon fiber having a hook drop value of 10 cm or more has good surface smoothness,
It is considered that since the interlayer thickness after curing is uniform and stable, the number of defective portions is small and CILS is improved.

Conventionally, a prepreg containing particles at a high concentration on the surface has a problem that tackiness is considerably weaker than a prepreg using the same base resin and excluding the particles. When the tack is reduced, adjacent prepregs are misaligned at the time of prepreg lamination, and an appropriate laminate cannot be obtained.

However, it was also found that the use of carbon fibers having a hook drop value of 10 cm or more improves the tack compared with a conventional prepreg of a particle-containing resin. It is thought that the good surface smoothness of the prepreg contributed. In addition, it has been found that the time-dependent change in tackiness is reduced. Compared with conventional prepreg, the movement of carbon fiber during leaving at room temperature is small,
It is considered that sinking of the resin is relatively unlikely to occur, and the resin is easily secured on the prepreg surface. It is considered that both the small twisting and twisting of the component [A] contribute to the securing of the surface resin, and the resin thickening due to the presence of the component [C].
Here, the tackiness is an index of the surface adhesiveness of the prepreg, which is generally 21.7 ± 1.7 ° C. (71 ± 3F),
It is evaluated by a tack tester in an environment with a humidity of 50 ± 5%. Specifically, PICM manufactured by Toyo Seiki Seisaku-sho, Ltd.
Using an A tack tester II, a cover glass of 18 × 18 mm ² was pressed against a prepreg for 5 seconds with a force of 0.4 kgf, and
Tackability is evaluated by pulling at a speed of 0 mm / min and resistance to peeling.

Further, it has been found that the compressive strength of the crossed laminate of the composite using the prepreg of the present invention is greatly improved as compared with the value expected from the conventional prepreg. Generally, the compressive strength of a cross-laminate of fiber-reinforced composite materials can be calculated and predicted from the compressive strength of a unidirectional laminate of the same prepreg using laminate theory. It was the prior art that if the strength of the one-way laminate was the same, then the strength of the cross laminate would be approximately equal. However, in the case of the prepreg of the present invention, the compressive strength (LCS) of the cross-laminate is significantly higher than that of the particle-containing prepreg of the prior art, even though the compressive strength of the unidirectional laminate is equal. I understand. In the compression test of the cross-laminated plate, a cross layer (for example, a ± 45 ° layer or a layer outside the 0 ° layer (a layer in which continuous fibers are arranged as a reinforcing material in the load application direction) outside the 0 ° layer in the test piece before the total failure occurs. (90 ° layer) often occurs. Surprisingly, in the case of the prepreg of the present invention, the peeling of the cross layer before the total destruction does not occur, or even if it does occur, as compared with the case of the particle-containing prepreg of the prior art. As a result, it is possible to bear a larger load until the whole is destroyed and to show high strength. It is considered that such an effect is due to both the uniformity of the interlayer thickness between the laminates due to the small twist and twist of the component [A] and the increase in the peeling resistance due to the presence of the component [C].

LCS is Boeing Spec for perforated plate compressive strength.
Evaluation is performed on a non-perforated plate using the measurement method described in the Certification Support Standard BSS7260. The specimen size is
Length (load application direction) is 304.8 mm x width 38.1 mm. Compressive strength is obtained without attaching reinforcing tabs to the side of the test piece.

The carbon fiber used in the present invention preferably has a substantially circular cross section. This is because when the resin is impregnated, the filaments are likely to be rearranged, and the resin is easily infiltrated between the carbon fibers.

A carbon fiber having a substantially circular cross-sectional shape is defined by the ratio (R / r) of the circumscribed circle radius R to the inscribed circle radius r of the cross-section defined as the degree of deformation. It means that the degree is 1.1 or less.

When the tensile strength of the carbon fiber is 4400 MPa or more and the elastic modulus is 270 GPa or less, it becomes possible to produce a hardened plate having a high tensile strength while maintaining the standard elastic modulus considered for a carbon fiber composite material. Therefore, it is preferable. The carbon fiber has a tensile strength of 5000 MPa or more, an elastic modulus of 270 GPa or more, and a density of 1.76 g.
/ Cm ³ or less is preferable because a hardened plate having higher strength, higher elastic modulus and lower specific gravity can be produced.

The carbon fibers used in the present invention are made of continuous fibers. If it is not continuous, it becomes difficult to sufficiently exhibit the strength of the reinforcing fiber when processed into a composite material. The shape and arrangement of the carbon fibers are not particularly limited, and may be, for example, unidirectional, random, sheet, mat, woven, or braided. In particular, for applications requiring high specific strength and specific elastic modulus, an arrangement in which carbon fibers are aligned in a single direction is most suitable, but a woven arrangement that is easy to handle is also included in the present invention. Are suitable.

Further, as the carbon fiber used in the present invention, a carbon fiber comprising a bundle of filaments arranged in one direction such as yarn, tow or strand is also suitable.
The yarn prepreg according to the present invention formed from these,
Tow prepregs and strand prepregs are preferred.

The prepreg of the present invention can be manufactured by several methods.

The base resin or the matrix resin is
Using a resin coating film coated on a film such as release paper, from both sides or one side of a sheet-like carbon fiber, the resin on the resin coating film is impregnated between the carbon fibers to prepare a prepreg. A so-called hot melt method is generally used. There is also a method of producing a prepreg by dipping and drying carbon fibers prepared in a resin dissolved in a solvent, referred to as a wet method.

Further, for the purpose of causing a large amount of particles to be present in the surface layer of the prepreg, a method of adhering a matrix resin film containing particles to one or both surfaces of a prepreg prepared by a usual method can be used.

Further, after preparing a prepreg containing no particles, the particles may be sprayed on one side or both sides.

[0070]

The present invention will be described in more detail with reference to the following examples. The details of the carbon fibers used in this example are as follows.

“Treca” (registered trademark) T800H-12K-40B (manufactured by Toray Industries, Inc.) Tensile strength 5490 MPa (560 kgf / mm ² ) Tensile modulus 294 GPa (30.0 × 10 ³ kgf / mm ² ) Fineness 0.445 g / m Density 1.81 g / cm ³ Hook drop value 8.2 cm Deformation degree (R / r) 1.37 “Treca” (registered trademark) M30G-18K-11E (manufactured by Toray Industries, Inc.) ) Tensile strength 5490 MPa (560 kgf / mm ² ) Tensile modulus 294 GPa (30.0 × 10 ³ kgf / mm ² ) Fineness 0.745 g / m Density 1.73 g / cm ³ Hook drop value 14.1 cm Deformation degree (R / r) 1.04 "Treca" (registered trademark) T700S-12K-50C (manufactured by Toray Industries, Inc.) Tensile strength 4900 MPa (500 kgf / mm ² ) Tensile modulus 230 GPa (23.5 × 10 ³ kgf / mm ² ) Fineness 0.800 g / m Density 1.80 g / cm ³ Hook drop 17.1 cm Deformation (R / r) 1.05 Carbon The tensile strength and tensile modulus of the fiber are JIS R7
601 was measured.

(Example 1) Bisphenol F
10 parts by weight of epoxy resin (Epiclon (registered trademark) 830 manufactured by Dainippon Ink and Chemicals, Inc.), 30 parts by weight of bisphenol A type epoxy resin (Epicoat (registered trademark) 825 manufactured by Yuka Shell Co., Ltd.) and tetraglycidyldiamino Diphenylmethane (TGDDM) (Sumitomo Chemical Co., Ltd. E
After mixing and dissolving 12.6 parts by weight of polyethersulfone (PES) with 60 parts by weight of LM-434), 21.6 parts by weight of polyamide fine particles (Trepearl TN, average particle size 12.5 μ, manufactured by Toray Industries, Inc.) are kneaded. And a curing agent 4,4′-diaminodiphenylsulfone (4,4′-diaminodiphenylsulfone).
4'-DDS) 45 parts by weight was kneaded to prepare a matrix resin. Apply this matrix resin on release paper 5
^Two films coated with ² g / m ² were produced. The carbon fibers “Treca” M30G-18K-11E were arranged while the coating surfaces faced to each other, and the carbon fibers were impregnated with a resin by pressing with a heating press roll to produce a unidirectional prepreg. This prepreg has a carbon fiber weight of 190 g / m ² , a prepreg weight of 294 g / m ² ,
The matrix resin content was 35.4%. The tack of the prepreg was “good” as shown in Table 1, and the change with time when left at room temperature was small.

The produced unidirectional prepreg was cut into a predetermined size and a predetermined number, and then laminated.

The lamination structure is (0) ₁₂ for CILS, CAI
(45/90 / -45 / 0) _3S for LCS, (45/90 / -45 / 0) _2S for LCS
It is. This was placed on an aluminum tool plate on which a release film was spread, further sealed with a release film and a bagging film, and evacuated through a nozzle. This was placed in an autoclave and heated at 180 ° C. under a pressure of 6 kg / cm ^2.
It was treated for 0 minutes to produce a cured plate. CILS in the atmosphere of 82.2 ± 5 ° C. after moisture absorption of this cured plate is 50.3MP.
a (7.3 ksi) and CAI is 241
MPa (35 ksi), LCS is 579 MPa (84 k
si).

Example 2 "Treca" T70 is used for carbon fiber.
A prepreg and a cured plate were produced in the same manner and under the same conditions as in Example 1 except that 0S-12K-50C was used.

The tack of the prepreg was “good”.
Further, CILS in the atmosphere of 82.2 ± 5 ° C. after the moisture absorption of the cured plate is as high as 58.6 MPa (8.5 ksi), CAI is 276 MPa (40 ksi), and LCS is
Was 593 MPa (86 ksi).

(Example 3) Bisphenol F in a kneading apparatus
10 parts by weight of epoxy resin (Epiclon 830 manufactured by Dainippon Ink and Chemicals Inc.), 30 parts by weight of bisphenol A type epoxy resin (Epicoat 825 manufactured by Yuka Shell Co., Ltd.) and tetraglycidyl diaminodiphenylmethane (TGDD)
M: Sumitomo Chemical Co., Ltd. ELM-434) 60 parts by weight of P
After mixing and dissolving 12.6 parts by weight of ES, 45 parts by weight of 4,4′-DDS as a curing agent was kneaded to prepare a matrix resin. This matrix resin was used as a primary resin.

In a kneading apparatus, 10 parts by weight of a bisphenol F type epoxy resin (Epiclon 8 manufactured by Dainippon Ink and Chemicals, Inc.)
30), 30 parts by weight of bisphenol A type epoxy resin (Epicoat 825 manufactured by Yuka Shell Co., Ltd.) and 60 parts by weight of tetraglycidyl diaminodiphenylmethane (TGDDM: ELM-434 manufactured by Sumitomo Chemical Co., Ltd.) and PES12.
After mixing and dissolving 6 parts by weight, 75.5 polyamide fine particles (Trepearl TN average particle size 12.5 μm, manufactured by Toray Industries, Inc.) 75.5
Parts by weight, and 4,4′-DDS as a curing agent
Of 45 parts by weight was kneaded to prepare a matrix resin.
This matrix resin was used as a secondary resin.

Two pieces of the primary resin film-coated on release paper with a basis weight of 31.5 g / m ² were prepared. The carbon fibers “Treca” M30G-18K-11E were arranged while the coating surfaces faced to each other, and the carbon fibers were impregnated with a resin by pressing with a heating press roll to prepare a unidirectional primary prepreg. This primary prepreg has a carbon fiber weight of 190 g / m ² , a prepreg weight of 253 g / m ² ,
The matrix resin content was 24.9%.

Next, two sheets of the secondary resin film-coated on release paper at a basis weight of 20.5 g / m ² were prepared. While facing the secondary resin coating film, the secondary prepreg was prepared by passing through the primary prepreg as described above and pressurizing with a hot press roll in the same manner as the primary. This prepreg has a carbon fiber weight of 190 g.
/ M ² , prepreg weight 294 g / m ² , and matrix resin content 35.4%. The tack of the prepreg was "very good".

Using the prepreg thus produced, a cured plate was produced in the same manner and under the same conditions as in Example 1.

The CILS in the atmosphere at 82.2 ± 5 ° C. after moisture absorption of the cured plate is 52.4 MPa (7.6 ksi), the CAI is 215 MPa (36 ksi), and the LCS is 5
It was 72 MPa (83 ksi).

(Example 4) "Treca" T70 is used for carbon fiber.
A prepreg and a cured plate were produced in the same manner and under the same conditions as in Example 3 except that 0S-12K-50C was used.

The tack of the prepreg was “very good”. Further, CILS in an atmosphere of 82.2 ± 5 ° C. after moisture absorption of the cured plate is 53.8 MPa (7.8 ksi), CAI is 297 MPa (43 ksi), and LCS is 5
It was 86 MPa (85 ksi).

(Example 5) SP-5 was added to polyamide fine particles.
A prepreg and a cured plate were produced in the same manner and under the same conditions as in Example 3 except that 00 (average particle size: 5 μ) was used.

The tack of the prepreg was “very good”. Further, CILS in an atmosphere of 82.2 ± 5 ° C. after moisture absorption of the cured plate is 34.5 MPa (5.0 ksi), CAI is 255 MPa (37 ksi), and LCS is 5
It was 93 MPa (86 ksi).

(Example 6) "Treca" T70 is used for carbon fiber.
A prepreg and a hardened plate were produced in the same manner and under the same conditions as in Example 5 except that 0S-12K-50C was used.

The tack of the prepreg was “very good”. The CILS in the atmosphere at 82.2 ± 5 ° C. after moisture absorption of the cured plate was 44.1 MPa (6.4 ksi), the CAI was 262 MPa (38 ksi), and the LCS was 6 MPa.
It was 14 MPa (89 ksi).

(Example 7) Bisphenol F in a kneading apparatus
10 parts by weight of epoxy resin (Epiclon 830 manufactured by Dainippon Ink and Chemicals, Inc.) and tetraglycidyl diaminodiphenylmethane (TGDDM: ELM manufactured by Sumitomo Chemical Co., Ltd.)
-434) 90 parts by weight of polyether sulfone (PE
S) After mixing and dissolving 12.7 parts by weight, 3,3'-diaminodiphenylsulfone (3,3'-
DDS) was kneaded at 32.5 parts by weight to prepare a matrix resin. This matrix resin was used as a primary resin.

In a kneading apparatus, 10 parts by weight of a bisphenol F type epoxy resin (Epiclon 830 manufactured by Dainippon Ink and Chemicals, Inc.) and tetraglycidyl diaminodiphenylmethane (TGDDM: ELM-434 manufactured by Sumitomo Chemical Co., Ltd.) 9
After mixing and dissolving 4.3 parts by weight of polyethersulfone (PES) with 0 parts by weight, 19.9 parts by weight of polyamide fine particles (SP-500, manufactured by Toray Industries, Inc., average particle size: 5 μm) are kneaded, and a curing agent is further added. 3,3'-DDS 3
2.5 parts by weight were kneaded to prepare a matrix resin.
This matrix resin was used as a secondary resin.

Two pieces of primary resin film-coated on release paper at a basis weight of 31.5 g / m ² were prepared. While the coated surfaces faced each other, carbon fibers “Treca” T70ST700S-12K-50C were arranged and pressed with a heated press roll to impregnate the carbon fibers with the resin to prepare a unidirectional primary prepreg. The primary prepreg has a carbon fiber weight of 190 g / m ² and a prepreg weight of 25.
The content was 3 g / m ² and the matrix resin content was 24.9%.

Next, two sheets of the secondary resin film-coated on release paper with a basis weight of 20.5 g / m ² were prepared. While facing the secondary resin coating film, the secondary prepreg was prepared by passing through the primary prepreg as described above and pressurizing with a hot press roll in the same manner as the primary. This prepreg has a carbon fiber weight of 190 g.
/ M ² , prepreg weight 294 g / m ² , and matrix resin content 35.4%. The tack of the prepreg was “very good”.

A cured plate was prepared from the prepared prepreg in the same manner and under the same conditions as in Example 1.

The CILS in the atmosphere at 82.2 ± 5 ° C. after the moisture absorption of the cured plate was 42.1 MPa (6.1 ks).
i) and CAI is 276 MPa (40 ksi), L
CS was 593 MPa (86 ksi).

(Comparative Example 1) "Treca" T80 is used for carbon fiber.
Except that 0H-12K-40B was used, a prepreg and a cured plate were produced under the same method and conditions as in Example 1.

The tack of the prepreg was “poor” and was inferior to those of Examples 1 and 2. Further, CILS in an atmosphere of 82.2 ± 5 ° C. after moisture absorption of the cured plate is 47.6MP.
a (6.9 ksi), which was inferior to Examples 1 and 2. The CAI is 262 MPa (38 ks).
i), LCS was 503 MPa (73 ksi).

(Comparative Example 2) "Treca" T80 was used for carbon fiber.
A prepreg and a cured plate were produced in the same manner and under the same conditions as in Example 3 except that 0H-12K-40B was used.

The tack of the prepreg was “slightly poor”, which was inferior to those of Examples 3 and 4. Further, CILS in an atmosphere of 82.2 ± 5 ° C. after moisture absorption of the cured plate was 49.0.
MPa (7.1 ksi), which was inferior to Examples 3 and 4. CAI is 345 MPa (50 ks).
i), LCS was 510 MPa (74 ksi).

(Comparative Example 3) "Treca" T80 was used for carbon fiber.
Except that 0H-12K-40B was used, a prepreg and a cured plate were produced in the same manner and under the same conditions as in Example 5.

The tack of the prepreg was “slightly poor”, which was inferior to those of Examples 5 and 6. Further, CILS in an atmosphere of 82.2 ± 5 ° C. after moisture absorption of the cured plate was 33.1.
MPa (4.8 ksi), which was inferior to Examples 5 and 6. The CAI is 324 MPa (47 ks).
i), LCS was 517 MPa (75 ksi).

(Comparative Example 4) "Treca" T80 was used for carbon fiber.
A prepreg and a cured plate were produced in the same manner and under the same conditions as in Example 7 except that 0H-12K-40B was used.

The tack of the prepreg was “slightly poor”, which was inferior to that of Example 7. Further, CILS in an atmosphere of 82.2 ± 5 ° C. after moisture absorption of the cured plate is 34.5MP.
a (5.0 ksi), which was inferior to Example 7. CAI is 303MPa (44ksi), L
CS was 503 MPa (73 ksi).

The results of the examples and comparative examples are summarized in Table 1.

[0104]

[Table 1]

[Table 2]

[0105]

According to the prepreg of the present invention, the fiber reinforced composite material obtained by using the prepreg has excellent CILS at high temperature after moisture absorption while maintaining high impact resistance such as CAI. Not only can it be obtained, but also the tack of the prepreg can be made good and the change with tack with time can be suppressed.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hajime Kishi 1515 Address Tsutsui, Matsumae-cho, Iyo-gun, Ehime Prefecture Toray Co., Ltd. (72) Inventor Shoji Yamane 1515 Address Tsutsui, Matsumae-cho, Iyo-gun, Ehime Prefecture Toray Ehime Plant Co., Ltd.

Claims (6)

[Claims] In a prepreg obtained by impregnating a carbon fiber satisfying the requirement [A] with a resin satisfying the requirement [B], particles satisfying the requirement [C] are present in the prepreg in an amount of 20% by weight or less. A prepreg characterized by being distributed at a higher concentration on the surface than on the inside. [A]: carbon fiber composed of continuous fibers having a hook drop value of 10 cm or more [B]: base resin composed mainly of a thermosetting resin [C]: particles having a particle diameter of 150 μm or less made of a thermoplastic resin. 2. The prepreg according to claim 1, wherein the tensile strength of the carbon fiber of the component [A] is 4400 MPa or more. 3. The prepreg according to claim 2, wherein the carbon fiber of the constituent element [A] has a tensile strength of 5000 MPa or more, an elastic modulus of 270 GPa or more, and a density of 1.76 g / cm ³ or less. 4. The prepreg according to claim 1, wherein the cross-sectional shape of the carbon fiber of the component [A] is substantially circular. 5. A step of preparing a sheet comprising a carbon fiber bundle comprising a number of continuous carbon filaments and having a fiber entanglement with a hook drop value of 10 cm or more; and (b) thermosetting. A matrix resin comprising a mixture of a base resin mainly composed of a thermoplastic resin and particles of a thermoplastic resin having a particle size of 150 μm or less in a weight of 20% or less of the weight of the completed prepreg is formed on a release film. A step of preparing a coated resin coating film; and (c) stacking the resin coating film on the sheet of carbon fiber bundle in a state where the matrix resin is in contact with the surface of the sheet of carbon fiber bundle. (D) heating and pressing the laminated sheet to form a multi-layered carbon fiber bundle; Between carbon filaments, wherein the base resin is impregnated allowed obtained resin-impregnated molded body, steps are formed, a method of manufacturing a prepreg consisting of capital. 6. A step of preparing a carbon fiber sheet comprising a plurality of continuous carbon filaments and a carbon fiber bundle having a fiber entanglement having a hook drop value of 10 cm or more, and (b) heat treatment. A step of preparing a first resin coating film in which a base resin mainly composed of a curable resin is coated on a first release film;
(C) forming a first laminated sheet in which the first resin coating film is superimposed on the sheet made of the carbon fiber bundle while the base resin is in contact with the surface of the sheet made of the carbon fiber bundle. (D)
A step in which the first laminated sheet is heated and pressed to form a first resin-impregnated molded body impregnated with the base resin between a number of carbon filaments of the carbon fiber bundle; (E) a matrix resin comprising a mixture of a base resin mainly composed of a thermosetting resin and particles of a thermoplastic resin having a particle size of 150 μm or less in a weight of 20% or less of the weight of the completed prepreg. A step of preparing a second resin coating film coated on a second release film; and (f) a matrix resin of the second resin coating film on a surface of the first resin impregnated molded body. Forming a second laminated sheet in which the second resin coating film is superimposed on the first resin-impregnated molded body in a state in contact with the second resin coating film;
(G) a step of heating and pressurizing the second laminated sheet to form a second resin-impregnated molded body in which the matrix resin and the base resin are integrated with each other. Production method.