JP2017190380A - Manufacturing method of prepreg - Google Patents

Abstract

An object of the present invention is to provide a method for producing a prepreg that can obtain a fiber-reinforced composite material exhibiting excellent toughness. A method for producing a prepreg comprising at least a fiber reinforcing material sheet, a curable resin, and thermoplastic resin particles, wherein two functional groups capable of reacting with the curable resin are formed on the surfaces of the thermoplastic resin particles. A method for producing a prepreg including a step of imparting the above organic matter and a step of heat-treating the thermoplastic resin particles and the organic matter. In the step of heat-treating the thermoplastic resin particles and the organic matter, it is preferable to heat-treat at a temperature equal to or lower than the melting point of the thermoplastic resin particles. Further, the organic substance having two or more functional groups capable of reacting with the curable resin has one or more of an epoxy group, an amide group, an amino group, an isocyanate group, a carbodiimide group, and a carboxyl group as functional groups. is preferably [Selection figure] None

Description

  The present invention relates to a method for producing a prepreg capable of obtaining a fiber-reinforced composite material having excellent interlayer toughness.

  Fiber reinforced composite materials (hereinafter referred to as composite materials) that use carbon fibers, aramid fibers, etc., as reinforcing fibers are used in aerospace, including structural materials for aircraft and automobiles, due to their high specific strength and specific modulus. Widely used in sports and leisure applications such as industrial applications, tennis rackets, golf shafts and fishing rods. Various methods are used for manufacturing the composite material, and a method using a prepreg which is a sheet-like intermediate base material in which reinforcing fibers are impregnated with a matrix resin is widely used. In this method, a composite material molding is usually obtained by laminating a plurality of prepregs and then heating.

  As the matrix resin used for the composite material, both a curable resin and a thermoplastic resin are used, and a curable resin is often used from the viewpoint of heat resistance and productivity. In general, curable resins are excellent in heat resistance, adhesion to reinforcing fibers, dimensional stability, and chemical resistance, but have hard and brittle properties. For this reason, when a curable resin is used as the matrix resin, the composite material is excellent in dimensional stability and mechanical properties such as strength and rigidity, but on the other hand, the low toughness derived from the curable resin is also reflected.

  In order to improve the toughness and impact resistance of a curable resin used as a matrix resin, a method of dispersing fine particles such as a thermoplastic resin, a thermosetting resin, a rubber material, and an inorganic material in the curable resin is often used. Yes. (For example, Patent Document 1) When these fine particles are used, the effect of improving the toughness and impact resistance of the curable resin is influenced by the adhesion between the fine particles and the curable resin in addition to the properties of the fine particles used. If the adhesion between the fine particles and the curable resin is insufficient, the fine particles and the curable resin are peeled off, and the effect of improving the toughness and impact resistance of the curable resin by the fine particles is not sufficiently exhibited.

  Therefore, in order to improve the adhesion between the fine particles and the curable resin, for example, Patent Document 2 proposes to use inorganic particles surface-treated with a coupling agent having a functional group that reacts with the curable resin. However, in this method, a strong bond is obtained between the curable resin and the coupling agent by a chemical bond, but no chemical bond is obtained between the coupling agent and the inorganic particles. The adhesiveness of was insufficient.

  Patent Document 3 discloses a fine particle in which a thermoplastic resin and a curable resin are mixed and reacted as fine particles excellent in adhesiveness with a curable resin, and a cross-linked polymer of the thermoplastic resin and the curable resin forms a network structure. A method of using is disclosed. However, in this method, the adhesion between the fine particles and the curable resin as the matrix resin is only due to the affinity between the curable resin component contained in the fine particles and the molecule of the curable resin of the matrix resin. The adhesiveness of the curable resin was insufficient.

It has also been proposed to use thermoplastic resin fine particles whose surface is coated with a cured product of a curable resin as fine particles for improving the toughness and impact resistance of the curable resin (for example, Patent Document 4, 5) However, these are intended to improve the heat resistance of the thermoplastic resin, and the adhesion between the fine particles and the curable resin as the matrix resin is only due to the affinity between the fine particles and the matrix resin molecules. In addition, the adhesion between the fine particles and the matrix resin was insufficient.
Therefore, there is a demand for a method for producing a prepreg that can improve the adhesion between the fine particles and the curable resin and obtain a composite material exhibiting excellent toughness.

JP-A 64-26651 JP-A-8-157620 JP-A-1-104624 JP 2010-116484 A International Publication No. 2015/097283

  The objective of this invention is providing the manufacturing method of the prepreg which can obtain the fiber reinforced composite material which expresses the outstanding toughness.

The method for producing a prepreg of the present invention is a method for producing a prepreg comprising at least a fiber reinforcing material sheet, a curable resin, and thermoplastic resin particles, and reacts with the curable resin on the surface of the thermoplastic resin particles. It is a manufacturing method of a prepreg including the process of providing the organic substance which has two or more functional groups which can do, and the process of heat-processing the said thermoplastic resin particle and organic substance. In the step of heat-treating the thermoplastic resin particles and the organic matter, the heat treatment is preferably performed at a temperature not higher than the melting point of the thermoplastic resin particles.
An organic substance having two or more functional groups capable of reacting with the curable resin has one or more of epoxy groups, amide groups, amino groups, isocyanate groups, carbodiimide groups, and carboxyl groups as functional groups. It is preferable that

  According to the prepreg manufacturing method of the present invention, it is possible to obtain a prepreg that provides a fiber-reinforced composite material excellent in impact resistance and interlaminar fracture toughness strength.

  The method for producing a prepreg of the present invention is a method for producing a prepreg comprising at least a fiber reinforcing material sheet, a curable resin, and thermoplastic resin particles, and reacts with the curable resin on the surface of the thermoplastic resin particles. It is a manufacturing method of a prepreg including the process of providing the organic substance which has two or more functional groups which can do, and the process of heat-processing the said thermoplastic resin particle and organic substance.

  A functional group that reacts with the curable resin can be imparted to the surface of the thermoplastic resin particle by imparting an organic substance having two or more functional groups to the surface of the thermoplastic resin particle and then performing a heat treatment. The thermoplastic resin particles having functional groups that react with the curable resin on the surface are excellent in adhesiveness to the curable resin that is a matrix resin, and can give excellent interlayer toughness when made into a composite material. Therefore, when the method for producing a prepreg of the present invention is used, a prepreg that provides a composite material excellent in impact resistance and interlaminar fracture toughness strength can be obtained.

  In the present invention, the heat treatment in the step of heat-treating the thermoplastic resin particles and the organic substance is preferably performed at a temperature not higher than the melting point (Tm) of the thermoplastic resin particles, and is heat-treated at a temperature not higher than Tm and not lower than Tm-30 ° C. More preferably. By performing the heat treatment at a temperature lower than the melting point of the thermoplastic resin particles, deformation of the particles due to the heat treatment can be suppressed. Furthermore, when the heat treatment is performed near the melting point of the thermoplastic resin particles, the particle surface melts, so that the functional group of the organic substance and the thermoplastic resin on the particle surface easily form a covalent bond, and the matrix resin The adhesiveness is likely to be higher.

An organic substance having two or more functional groups capable of reacting with the curable resin has one or more of epoxy groups, amide groups, amino groups, isocyanate groups, carbodiimide groups, and carboxyl groups as functional groups. It is preferable that
According to the prepreg manufacturing method of the present invention as described above, a prepreg that provides a composite material excellent in impact resistance and interlaminar fracture toughness strength can be obtained.

Hereafter, the manufacturing method of the prepreg of this invention is demonstrated in detail.
(1) Fiber Reinforcement Sheet The fiber reinforcement used in the present invention is not particularly limited, and examples thereof include carbon fiber, glass fiber, aromatic polyamide fiber, polyimide fiber, polybenzoxazole fiber, wholly aromatic polyester fiber, and the like. Can be mentioned. These can be used alone or in combination of two or more. In order to improve the mechanical properties of the composite material, it is preferable to use carbon fibers having excellent tensile strength. The form of the fiber reinforcing material is preferably a sheet-like material such as a woven fabric, a multiaxial woven fabric, and a unidirectionally aligned product.

(2) Curable resin Preferred examples of the curable resin used in the present invention are listed below. These curable resins can be appropriately selected and used alone or in combination of two or more. Preferred curable resins include epoxy resins, modified epoxy resins, bismaleimide resins, oxetane resins, benzoxazine resins, polyester resins, vinyl ester resins, cyanate ester resins and the like. Particularly preferable examples include an epoxy resin and a modified epoxy resin.
As the epoxy resin, any known epoxy resin can be used and is not particularly limited. Examples thereof include bifunctional epoxy resins such as bisphenol-type epoxy resins, alcohol-type epoxy resins, biphenyl-type epoxy resins, hydrophthalic acid-type epoxy resins, dimer acid-type epoxy resins, and alicyclic epoxy resins.

  Bifunctional epoxy resins represented by the bisphenol type have various grades ranging from liquid to solid depending on the difference in molecular weight, and are intended components for adjusting viscosity by mixing as appropriate. Examples of the bisphenol type epoxy resin include bisphenol A type resin, bisphenol F type resin, bisphenol AD type resin, bisphenol S type resin, and the like. Specific product names include jER815 (product name), jER828 (product name), jER834 (product name), jER1001 (product name), jER807 (product name) manufactured by Japan Epoxy Resin Co., Ltd. -710 (trade name), EXA1514 (trade name) manufactured by Dainippon Ink & Chemicals, Inc. can be exemplified. Specific product names of alicyclic epoxy resins include Araldite CY-179 (product name), CY-178 (product name), CY-182 (product name), CY-183 (product name), etc. manufactured by Huntsman. Can be illustrated. Examples of other epoxy resins include glycidyl ether type epoxy resins such as tetrakis (glycidyloxyphenyl) ethane and tris (glycidyloxyphenyl) methane, glycidylamine type epoxy resins such as tetraglycidyldiaminodiphenylmethane, and naphthalene type epoxy resins. And a phenol novolac epoxy resin which is a novolac epoxy resin, a polyfunctional epoxy resin such as a cresol novolac epoxy resin, a phenol epoxy resin, and the like.

Various modified epoxy resins such as urethane-modified epoxy resin and rubber-modified epoxy resin can also be used. Specific examples of the trade name of the urethane-modified bisphenol A epoxy resin include Adeka Resin EPU-6 (trade name) and EPU-4 (trade name) manufactured by Asahi Denka. Specific product names of the phenol novolac type epoxy resin include jER152 (product name), jER154 (product name) manufactured by Japan Epoxy Resin, DEN431 (product name), DEN485 (product name), and DEN438 (product name) manufactured by Dow Chemical. Name), Epicron N740 (trade name) manufactured by DIC, and the like.
Specific product names of the cresol novolak type epoxy resin include Araldite ECN1235 (product name), ECN1273 (product name), ECN1280 (product name), Nippon Kayaku EOCN102 (product name), and EOCN103 (product name) manufactured by Huntsman. ), EOCN104 (trade name), and the like.

(3) Thermoplastic resin particles The thermoplastic resin particles used in the present invention include curable resin-soluble thermoplastic resin particles and curable resin-insoluble thermoplastic resin particles, which are curable resin-insoluble thermoplastic resin particles. It is preferable. The curable resin-soluble thermoplastic resin particles are thermoplastic resins that can be partially or wholly dissolved in the curable resin by heating or the like. On the other hand, the curable resin-insoluble thermoplastic resin refers to a thermoplastic resin that does not substantially dissolve in the curable resin at a temperature at which FRP is molded or at a temperature lower than that. That is, it refers to a thermoplastic resin whose particle size does not change when resin particles are put into a curable resin and stirred at a temperature at which FRP is molded. In general, the temperature at which FRP is molded is 100 to 190 ° C.

  As the curable resin-insoluble thermoplastic resin, for example, when an epoxy resin is used as the curable resin, polyamide, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyester, polyamide imide, polyimide, polyether ketone, polyether ether ketone, polyethylene Examples include phthalate, polyether nitrile, and polybenzimidazole. Among these, polyamide, polyamideimide, and polyimide are preferable because of high toughness and heat resistance. Polyamide and polyimide are particularly excellent in improving toughness against FRP. These may be used alone or in combination of two or more. Moreover, these copolymers can also be used.

In particular, amorphous polyimide, nylon 6 (registered trademark) (polyamide obtained by ring-opening polycondensation reaction of caprolactam), nylon 12 (polyamide obtained by ring-opening polycondensation reaction of lauryl lactam), amorphous nylon By using a polyamide such as (also called transparent nylon, which does not cause crystallization of the polymer or has a very low crystallization rate of the polymer), the heat resistance of the obtained FRP can be particularly improved.
The content of the curable resin-insoluble thermoplastic resin in the curable resin composition is appropriately adjusted according to the viscosity of the curable resin composition. From the viewpoint of workability of the prepreg, the amount is preferably 5 to 60 parts by mass and more preferably 15 to 40 parts by mass with respect to 100 parts by mass of the curable resin.

(4) Organic substance having two or more functional groups capable of reacting with the curable resin The organic substance having two or more functional groups capable of reacting with the curable resin used in the present invention is not particularly limited. An organic substance having any one or more of a group, an amide group, an amino group, an isocyanate group, a carbodiimide group, and a carboxyl group is preferable.
Examples of the organic substance having an epoxy group include the above-mentioned epoxy resin compounds, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, 1,7-octadiene diepoxide, ethylene glycol diglycidyl ether, tris (glycidyloxyphenyl). ) Methane, tetraglycidyldiaminodiphenylmethane, etc. are preferably used.
Examples of the organic substance having an amino group include tetramethylenediamine, 1,2-bis (2-aminoethoxy) ethane, 1,6-diaminohexane, and the like. Hexamethylene diisocyanate or the like can be used as the organic substance having an isocyanate group.

(5) Other components (5-1) Curing agent As the curing agent for curing the curable resin, a known curing agent can be used. As specific examples of the curing agent, when an epoxy resin is used as the curable resin, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 4,4′-diamino-3,3′- Examples include diethyl-5,5′-dimethyldiphenylmethane.

(5-2) Additive The curable resin composition of the present invention essentially comprises the above-described thermoplastic resin particles and curable resin, but as necessary without departing from the effects of the present invention. As appropriate, it may contain various additives such as curing accelerators, reactive diluents, fillers, anti-aging agents, flame retardants and pigments other than the above-mentioned components. Examples of the curing accelerator include basic curing agents such as acid anhydrides, Lewis acids, dicyandiamides and imidazoles, urea compounds, and organic metal salts. More specifically, examples of the acid anhydride include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Examples of the Lewis acid include boron trifluoride salts, and more specifically, BF ₃ monoethylamine, BF ₃ benzylamine, and the like. Examples of imidazoles include 2-ethyl-4-methylimidazole, 2-ethylimidazole, 2,4-dimethylimidazole, and 2-phenylimidazole. Moreover, 3- [3,4-dichlorophenyl] -1,1-dimethylurea that is a urea compound, Co [III] acetylacetonate that is an organometallic salt, and the like can be exemplified. Examples of the reactive diluent include reactive diluents such as polypropylene diglycol / diglycidyl ether and phenyl glycidyl ether.

(6) Processing step of thermoplastic resin particles (6-1) Step of applying organic substance having two or more functional groups The method of applying organic substance to the surface of thermoplastic resin particles is not particularly limited, but organic substance The method of mixing the thermoplastic resin particles in a solvent is preferred. At this time, the heat treatment described later may be performed simultaneously.
Although there is no restriction | limiting in particular as a solvent used when mixing, It is preferable that it is a poor solvent with respect to a thermoplastic resin particle. Moreover, when an organic substance is a liquid component, you may take the method of mixing in absence of a solvent.

(6-2) Step of heat treatment In the present invention, the heat treatment of the step of heat-treating the thermoplastic resin particles and the organic substance is preferably performed at a temperature equal to or lower than the melting point (Tm) of the thermoplastic resin particles. It is more preferable to perform heat treatment at a temperature of Tm-30 ° C or higher. By performing the heat treatment at a temperature lower than the melting point of the thermoplastic resin particles, deformation of the particles due to the heat treatment can be suppressed. Furthermore, when the heat treatment is performed near the melting point of the thermoplastic resin particles, the particle surface melts, so that the functional group of the organic substance and the thermoplastic resin on the particle surface easily form a covalent bond, and the matrix resin The adhesiveness is likely to be higher. You may perform heat processing simultaneously with the process of providing the above-mentioned organic substance.
There is no restriction | limiting in particular as a heating method, Well-known heating methods, such as oven, a vapor | steam, a hot air, a microwave, a radiation, can be used.

(7) Manufacturing method of curable resin composition The manufacturing method of curable resin composition is not specifically limited, You may use any conventionally well-known method. For example, the kneading of each component may be performed in a single stage or may be performed in multiple stages by sequentially adding each component. When adding each component sequentially, it can add in arbitrary orders. For example, when adding a curing agent and a viscosity adjusting thermoplastic resin to the curable resin, after kneading and melting a part or all of the viscosity adjusting thermoplastic resin in advance in the curable resin, the viscosity is adjusted. Then, kneading is performed while sequentially adding thermoplastic resin particles and a curing agent. The order of kneading and addition is not particularly limited, but it is preferable to add the curing agent last from the viewpoint of the storage stability of the resin composition.

  The kneading temperature during the production of the curable resin composition may be appropriately adjusted according to the type of the curable resin, the thermoplastic resin particles, the curing agent, the reaction start temperature, etc., but is preferably in the range of 10 to 150 ° C. When it exceeds 150 degreeC, a partial hardening reaction will start and the storage stability of the resin composition obtained may fall. If it is lower than 10 ° C., the viscosity of the resin composition is high, and it may be difficult to knead substantially. Preferably it is 20-120 degreeC, More preferably, it is the range of 30-100 degreeC.

  A conventionally well-known thing can be used as a kneading machine apparatus used at the time of curable resin composition manufacture. Specific examples include a roll mill, a planetary mixer, a kneader, an extruder, a Banbury mixer, a mixing vessel provided with a stirring blade, and a horizontal mixing vessel. The kneading of each component can be performed in the air or in an inert gas atmosphere. In particular, when kneading is performed in the air, an atmosphere in which temperature and humidity are controlled is preferable. Although not particularly limited, for example, it is preferable to knead in a low humidity atmosphere such as a temperature controlled at a constant temperature of 30 ° C. or lower or a relative humidity of 50% RH or lower.

(8) Manufacturing method of prepreg The manufacturing method of a prepreg is not specifically limited, It can manufacture using any conventionally well-known method. For example, a curable resin composition is applied to a release paper in a thin film form, and the resin film obtained by peeling is laminated on a sheet-like fiber reinforcement to impregnate the curable resin composition. Examples thereof include a so-called hot melt method and a solvent method in which a curable resin composition is formed into a varnish using an appropriate solvent, and the fiber reinforced material sheet is impregnated with the varnish. Among these, the prepreg of the present invention can be particularly preferably produced by a hot melt method which is a conventionally known production method.

  The method for forming the curable resin composition into a resin film or sheet is not particularly limited, and any conventionally known method can be used. More specifically, it can be obtained by casting and casting on a support such as release paper or film by die extrusion, applicator, reverse roll coater, comma coater or the like. The resin temperature at the time of forming a film or a sheet can be appropriately set according to the resin composition / viscosity, but the same conditions as the kneading temperature in the method for producing the curable resin composition described above can be suitably used. . The prepreg of the present invention preferably has a curable resin composition content (RC) of 15 to 70% by weight. If it is less than 15% by weight, voids or the like are generated in the obtained composite material, and the mechanical properties may be deteriorated. If it exceeds 70% by weight, the reinforcing effect by the reinforcing fibers becomes insufficient, and the mechanical properties in comparison with weight may be substantially low. Preferably it is the range of 20-60 mass%, More preferably, it is the range of 30-50 weight%. Here, the curable resin composition content (RC) is a ratio calculated from a change in weight when the resin of the prepreg is decomposed by sulfuric acid decomposition. More specifically, a prepreg is cut out to 100 mm × 100 mm to prepare a test piece, its weight is measured, and the resin remaining in the sulfuric acid is immersed or boiled until the resin component is eluted, and the fiber remaining after filtration is washed with water. It is a value obtained by measuring and calculating the mass after washing with, and drying.

  Further, although not particularly limited, as a preferred form of a specific prepreg, for example, a reinforcing fiber layer composed of a reinforcing fiber and a resin composition impregnated between the reinforcing fibers, and the surface of the reinforcing fiber layer It is composed of a coated resin coating layer, and the thickness of the resin coating layer is 2 to 50 μm. When the thickness is less than 2 μm, tackiness becomes insufficient, and the molding processability of the prepreg may be significantly lowered. If it exceeds 50 μm, it will be difficult to wind the prepreg into a roll with a uniform thickness, and the molding accuracy may be significantly reduced. More preferably, it is 5-45 micrometers, More preferably, it is 10-40 micrometers.

The impregnation pressurization when the resin sheet is impregnated into the sheet-like fiber reinforcing material sheet may be any pressure in consideration of the viscosity and resin flow of the resin composition. The impregnation temperature of the resin sheet into the fiber reinforcement sheet is in the range of 50 to 150 ° C. When the temperature is lower than 50 ° C., the viscosity of the resin sheet is high, and the fiber reinforcing material sheet may not be sufficiently impregnated. When the temperature is 150 ° C. or higher, the curing reaction of the resin composition is started, and the storage stability of the prepreg may be reduced, or the drapeability may be reduced. Preferably, it is 60-145 degreeC, More preferably, it is 70-140 degreeC. Further, the impregnation can be performed in multiple stages at an arbitrary pressure and temperature in a plurality of times instead of once.
A composite material produced by molding and curing using a prepreg obtained by such means is excellent in impact resistance and interlaminar fracture toughness, so it can be used in aerospace applications, industrial applications, sports and leisure applications. It can be suitably used for many applications.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, evaluation of operating conditions and measurement of each physical property were performed by the following methods.
[Reinforced fiber substrate]
-The tensile strength and elastic modulus of the carbon fiber strand (Tenax IMS65 (brand name)) by Toho Tenax used were as follows.
・ Tensile strength: 5800 MPa
-Elastic modulus: 290 GPa

[Curable resin composition]
(Curable resin)
・ Glycidylamine type epoxy resin (trifunctional group) [Araldite MY0600 (trade name) manufactured by Huntsman Advanced Materials, Inc.] (MY0600)
・ Glycidylamine type epoxy resin (4 functional groups) [Araldite MY721 (trade name) manufactured by Huntsman Advanced Materials, Inc.] (MY721)
(Epoxy resin curing agent)
3,3′-diaminodiphenylsulfone [Aromatic amine-based curing agent manufactured by Wakayama Seika Co., Ltd.] (3,3′-DDS)

[Thermoplastic resin]
(Thermoplastic resin insoluble in curable resin)
・ Polyamide 12 [VESTSIN 2158 (trade name) manufactured by Daicel-Evonik Co., Ltd.] (PA12)
Average particle diameter: 20 μm Tensile modulus: 1400 MPa Melting point: 184 ° C. Density: 1.016 g / cm ³
Polyamide 1010 [VESTAMID BS1358 (trade name) manufactured by Daicel-Evonik Co., Ltd.] (PA1010) (thermoplastic resin insoluble in epoxy resin)
Average particle diameter: 20 μm Tensile modulus: 1500 MPa Melting point: 200 ° C. Density: 1.040 g / cm ³
Polyamide 6 [ORGASOL1002D NAT (trade name) manufactured by Arkema Corporation] (PA6) (a thermoplastic resin insoluble in epoxy resin)
Average particle diameter: 20 μm Tensile modulus: 1500 MPa Melting point: 217 ° C. Density: g / cm ³
(Thermoplastic resin soluble in curable resin)
Polyethersulfone [PES-5003P (trade name) manufactured by Sumitomo Chemical Co., Ltd.] (PES)
Average particle size: 20 μm

[Organic substance having two or more functional groups capable of reacting with curable resin]
・ Bisphenol A type epoxy resin (bifunctional) [Japan Epoxy Resin Co., Ltd. jER828 (trade name)] (jER828)
Hexamethylene diisocyanate (bifunctional) [Tokyo Chemical Industry Co., Ltd. H0324 (trade name)] (H0324)

[Measuring method]
(1) Average particle size The average particle size was measured by measuring the particle size distribution using a laser diffraction / scattering particle size analyzer (Microtrack method) MT3300 manufactured by Nikkiso Co., Ltd. ₅₀ ) was defined as the average particle size.

(2) Interlaminar toughness of composite materials (Mode I interlaminar toughness (GIc))
Interlaminar toughness of the composite material was evaluated by measuring interlaminar fracture toughness mode I (GIc) according to JIS K7086. The obtained prepreg was cut into a square having a side of 360 mm, then laminated, and two laminates were produced in which 10 layers were laminated in the 0 ° direction. In order to generate an initial crack, the release sheet was sandwiched between two laminates, and both were combined to obtain a prepreg laminate having a laminate configuration [0] ₂₀ . Using a normal vacuum autoclave molding method, molding was performed at a temperature of 180 ° C. for 2 hours under a pressure of 0.59 MPa. The obtained molded product was cut into a size of 20 mm wide × 195 mm long to obtain a specimen having an interlaminar fracture toughness mode I (GIc).
A test that uses a double cantilever interlaminar fracture toughness test method (DCB method) as a test method for GIc, and generates a 2-5 mm pre-crack (initial crack) from the tip of the release sheet, and then further propagates the crack. Went. The crosshead speed of the test specimen tensile tester was 0.5 mm / min until the crack growth reached 20 mm, 1 mm / min after reaching 20 mm, and measurement was performed at n = 5. GIc was calculated from the load, displacement, and crack length.

Example 1
In a beaker, 100 parts by mass of PA12 and 150 parts by mass of bisphenol A type epoxy resin were added, heated at 160 ° C. for 1 hour, and then cooled to room temperature. Acetone was then added to the beaker and the resulting suspension was filtered. The precipitate separated by filtration was further washed with acetone and dried at 100 ° C. for 2 hours to obtain white solid epoxy resin-modified PA12 particles.
In a kneader, 30 parts by mass of PES was added to 40 parts by mass of MY600 and 60 parts by mass of MY721, and the mixture was stirred with a stirrer at 100 ° C. for 30 minutes, and then the resin temperature was cooled to 70 ° C. or less. Next, 45 parts by mass of the epoxy resin-modified polyamide 12 particles obtained above and 60 parts by mass of 3,3′-DDS were kneaded to prepare an epoxy resin composition. The prepared epoxy resin composition was applied onto release paper using a film coater to prepare ^two 50 g / m ² resin films.
The carbon fiber bundle was aligned in one direction to prepare a carbon fiber base material (weight per unit: 190 g / m ² ). An epoxy resin film was bonded to both surfaces of the prepared carbon fiber base material, and the carbon fiber base material was impregnated with a hot melt method to prepare a prepreg (RC: 35%).
Using the prepared prepreg, a composite material was molded under conditions of a curing temperature of 180 ° C. and a heating rate of 2 ° C./min. The interlaminar fracture toughness of the obtained composite material was measured, and the results obtained are shown in Table 1.

(Example 2)
A prepreg was produced in the same manner as in Example 1 except that hexamethylene diisocyanate was used instead of bisphenol A type epoxy resin as an organic substance having two or more functional groups capable of reacting with the curable resin.
The interlaminar fracture toughness of the composite material molded using the prepared prepreg was measured, and the results obtained are shown in Table 1.

(Example 3)
Similar to Example 1 except that PA1010 was used instead of PA12 as the thermoplastic resin particles, and the heating temperature in the beaker to which an organic substance having two or more functional groups capable of reacting with the curable resin was added was changed to 180 ° C. Thus, a prepreg was produced.
The interlaminar fracture toughness of the composite material molded using the prepared prepreg was measured, and the results obtained are shown in Table 1.

Example 4
As in Example 1, except that PA6 was used as the thermoplastic resin particle instead of PA12, and the heating temperature in the beaker to which an organic substance having two or more functional groups capable of reacting with the curable resin was added was changed to 210 ° C. Thus, a prepreg was produced.
The interlaminar fracture toughness of the composite material molded using the prepared prepreg was measured, and the results obtained are shown in Table 1.

(Example 5)
A prepreg was produced in the same manner as in Example 1 except that the heating temperature in the beaker to which an organic substance having two or more functional groups capable of reacting with the curable resin was added was changed to 210 ° C.
The interlaminar fracture toughness of the composite material molded using the prepared prepreg was measured, and the results obtained are shown in Table 1.

(Comparative Example 1)
In a kneader, 30 parts by mass of PES was added to 40 parts by mass of MY600 and 60 parts by mass of MY721, and the mixture was stirred with a stirrer at 100 ° C. for 30 minutes, and then the resin temperature was cooled to 70 ° C. or less. Next, 45 parts by mass of untreated PA12 particles and 60 parts by mass of 3,3′-DDS were kneaded to prepare an epoxy resin composition. The prepared epoxy resin composition was applied onto release paper using a film coater to prepare ^two 50 g / m ² resin films.
The carbon fiber bundle was aligned in one direction to prepare a carbon fiber base material (weight per unit: 190 g / m ² ). An epoxy resin film was bonded to both surfaces of the prepared carbon fiber base material, and the carbon fiber base material was impregnated with a hot melt method to prepare a prepreg (RC: 35%).
Using the prepared prepreg, a composite material was molded under conditions of a curing temperature of 180 ° C. and a heating rate of 2 ° C./min. The interlaminar fracture toughness of the obtained composite material was measured, and the results obtained are shown in Table 1.

(Comparative Example 2)
A prepreg was produced in the same manner as in Comparative Example 1 except that PA1010 was used instead of PA12 as the thermoplastic resin particles.
The interlaminar fracture toughness of the composite material molded using the prepared prepreg was measured, and the results obtained are shown in Table 1.

(Comparative Example 3)
A prepreg was produced in the same manner as in Comparative Example 1 except that PA6 was used instead of PA12 as the thermoplastic resin particles.
The interlaminar fracture toughness of the composite material molded using the prepared prepreg was measured, and the results obtained are shown in Table 1.

Claims (3)

At least a fiber reinforced material sheet, a curable resin, and a method for producing a prepreg composed of thermoplastic resin particles,
A step of providing an organic substance having two or more functional groups capable of reacting with the curable resin on the surface of the thermoplastic resin particles;
The manufacturing method of the prepreg characterized by including the process of heat-processing the said thermoplastic resin particle and organic substance.   The method for producing a prepreg according to claim 1, wherein in the step of heat-treating the thermoplastic resin particles and the organic matter, the heat-treatment is performed at a temperature equal to or lower than the melting point of the thermoplastic resin particles.   Organic substance having two or more functional groups capable of reacting with the curable resin has one or more of epoxy group, amide group, amino group, isocyanate group, carbodiimide group, carboxyl group as the functional group The method for producing a prepreg according to claim 1 or 2.