Coating agent and intermediate substrate

Abstract

To provide a surface protective material which is rich in UV resistance, can protect a surface of a prepreg as a base material, prevents degradation by UV of a fiber-reinforced composite material and can prevent defects in coating, can control a resin flow, and has a small amount of volatilization in curing.SOLUTION: A coating agent for spraying or hand coating that is composed of an epoxy resin composition containing at least components [A] to [D] contains 90-100 pts.mass of [A], 15-75 pts.mass of [B], 0.05-75 pts.mass of [C] and 0.1-10 pts.mass of [D] with respect to 100 pts.mass of the whole epoxy resin. [A] Non-aromatic epoxy resin. [B] Pigment having an average particle diameter of 0.1-10 μm. [C] Non-aromatic thermoplastic resin. [D] Cationic or anionic curing agent.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a coating agent for spraying or manual coating composed of an epoxy resin composition excellent in light resistance, and an intermediate substrate obtained by applying the coating agent to the surface of a metal or the like.

Background Art

[0002] For products that require high structural performance such as aircraft structural members, wind turbine blades, automotive outer panels, and computer applications such as IC trays and laptop computer casings, prepregs produced by impregnating reinforcing fibers such as carbon fibers with thermosetting resins such as epoxy resins are often used. However, fiber composite materials obtained by curing general prepregs have low light resistance (UV resistance), and deteriorate and deform when the surface is exposed to light. Therefore, in recent years, there has been an increasing demand for imparting light resistance to the surface of fiber composite materials.

[0003] Patent Document 1 discloses a sheet material having UV shielding properties as a surface protection film for fiber composite materials. Patent Document 2 also discloses a resin composition having UV resistance, which is a combination of an epoxy resin containing no aromatic ring, a carboxylic anhydride also containing no aromatic ring, and an ultraviolet absorber. Non-aromatic epoxy generally has the characteristics of low molecular weight, weak intermolecular interaction, low viscosity, and easy volatilization.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technology disclosed in Patent Document 1, the epoxy resin composition used as the film material contains an aromatic ring, and there is a problem that the film material itself has poor UV resistance. Further, in the technology disclosed in Patent Document 2, since a carboxylic anhydride is applied as a curing agent for the epoxy resin composition, there is a problem that the degree of freedom in design is low in order to control the handleability as a surface protection material, the resin flow, and the volatilization during curing.

[0006] Therefore, it is an issue to realize a surface protection material that is rich in UV resistance, can protect the surface of the prepreg serving as the base material, can prevent deterioration of the fiber-reinforced composite material due to UV, prevent defects during painting, and can control the resin flow and has a small volatilization amount during curing.

Means for Solving the Problems

[0007] The present invention has the following configuration in order to solve such problems. That is, the coating agent of the present invention is a spray or brush-applied coating agent composed of an epoxy resin composition containing at least constituent elements [A] to [D], and contains 90 to 100 parts by mass of [A], 15 to 75 parts by mass of [B], 0.05 to 75 parts by mass of [C], and 0.1 to 10 parts by mass of [D] with respect to 100 parts by mass of the total epoxy resin. [A] Non-aromatic epoxy resin [B] Pigment having an average particle size of 0.1 to 10 μm [C] Non-aromatic thermoplastic resin [D] Cationic or anionic curing agent.

[0008] Further, the intermediate base material of the present invention is obtained by applying the above coating agent to the surface of a metal, a carbon fiber-reinforced composite material precursor, or a carbon fiber-reinforced composite material.

Effects of the Invention

[0009] According to the present invention, it is possible to provide a coating agent using an epoxy resin composition excellent in light resistance. 。In addition, by applying and integrating the coating agent on the surface of a metal, a carbon fiber reinforced composite material precursor, or a carbon fiber reinforced composite material, an intermediate substrate having light resistance on the surface can be provided.

Embodiments for Carrying Out the Invention

[0010] The coating agent of the present invention has the following composition.

[0011] A coating agent for spraying or manual application composed of an epoxy resin composition containing at least components [A] to [D], wherein [A] is 90 to 100 parts by mass, [B] is 15 to 75 parts by mass, [C] is 0.05 to 75 parts by mass, and [D] is 0.1 to 10 parts by mass with respect to 100 parts by mass of the total epoxy resin. [A] Non-aromatic epoxy resin [B] Pigment with an average particle size of 0.1 to 10 μm [C] Non-aromatic thermoplastic resin [D] Cationic or anionic curing agent.

[0012] The component [A] according to the present invention is a non-aromatic epoxy resin. Here, "aromatic" means those containing aromatic hydrocarbons or conjugated unsaturated heterocyclic compounds in the chemical structure, and the rest are "non-aromatic". That is, a non-aromatic epoxy resin refers to an epoxy resin that does not contain an aromatic hydrocarbon group or an unsaturated heterocyclic ring in its chemical structure.Examples of non-aromatic epoxy resins include alicyclic epoxy resins (epoxy resins containing cycloalkane rings), such as tetrahydroindene diepoxide, vinylcyclohexene oxide, (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate, dipentene dioxide, bis(3,4-epoxycyclohexylmethyl) adipate, dicyclopentadiene dioxide, bis(2,3-epoxycyclopentyl) ether, 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol, tetrakis-(3-cyclohexenylmethyl) modified epsilon-caprolactone of epoxidized butanetetracarboxylic acid, bi-7-oxabicyclo[4.1.0]heptane, dodecahydrobisphenol A diglycidyl ether, dodecahydrobisphenol F diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, hexahydrophthalic acid diglycidyl ester, hexahydroterephthalic acid diglycidyl ester, diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane (common name: hydrogenated bisphenol A type liquid epoxy resin). Specific examples of epoxy resins containing neither an aromatic ring, an amine nitrogen atom, a cycloalkane ring nor a cycloalkene ring include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol glycidyl ether, 1,6-hexanediol diglycidyl ether, neopentylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, sorbitol polyglycidyl ether, 1,4-bis(2-oxiranyl)butane, pentaerythritol polyglycidyl ether. Specific examples of monofunctional epoxy compounds (epoxy compounds containing only one oxirane ring) containing neither an aromatic ring nor an amine nitrogen atom include 4-tert-butyl glycidyl ether, butyl glycidyl ether, 1-butene oxide, 1,2-epoxy-4-vinylcyclohexane, 2-ethylhexyl glycidyl ether, and the like.

[0013] From the perspective of heat resistance, alicyclic epoxy resins are preferably used as the non-aromatic epoxy resins.

[0014] Commercially available products can be used as the non-aromatic epoxy resins. For example, "Celloxide (registered trademark)" 2021P, "Celloxide (registered trademark)" 8010, "Celloxide (registered trademark)" 2000, "Epolead (registered trademark)" GT401, "Celloxide (registered trademark)" 2081, EHPE3150 (manufactured by Daicel Chemical Industries, Ltd.), THI-DE (manufactured by JXTG Energy Corporation), TTA21, AAT15, TTA22 (manufactured by Sankyo Chemical Co., Ltd.), Ex-121, Ex-211, Ex-212, Ex-313, Ex-321, Ex-411 (manufactured by Nagase ChemteX Corporation), "Epolite (registered trademark)" 4000 (manufactured by Kyoeisha Chemical Co., Ltd.), ST-3000, ST-4000 (manufactured by Nippon Steel Chemical & Material Co., Ltd.), YX8000 (manufactured by Mitsubishi Chemical Corporation), EPALOY5000 (manufactured by Huntsman), etc.

[0015] By using at least two types of the non-aromatic epoxy resins, the reactivity of the epoxy resin composition can be controlled, and a good balance between the rapid curing property and the pot life of the epoxy resin composition can be obtained.

[0016] By containing 90% by mass or more of the non-aromatic epoxy resin with respect to the entire epoxy resin composition, high light resistance (UV resistance) can be obtained.

[0017] Also, when only an alicyclic epoxy resin is used in the epoxy resin composition, an epoxy resin cured product having high glass transition temperature while having UV resistance can be obtained.

[0018] Component [B] is a pigment (average particle size: 0.1 to 10 μm). Examples of pigments include barium sulfate, zinc sulfide, titanium oxide, molybdenum red, cadmium red, chromium oxide, titanium yellow, cobalt green, cobalt blue, ultramarine blue, barium titanate, carbon black, iron oxide, red phosphorus, copper chromate, and the like. The average particle size of the pigment needs to be 0.1 to 10 μm, preferably 0.1 to 5 μm, and more preferably 0.3 to 5 μm, so that an epoxy resin composition having high UV shielding properties can be obtained. Here, the average particle size is measured using LA-950 (manufactured by Horiba, Ltd.) using the laser diffraction scattering method. As the dispersion medium, the volume conversion result measured using "Araldite (registered trademark)" GY282 (component: bisphenol F type epoxy resin, manufactured by Huntsman Japan Co., Ltd.) is adopted as the particle size distribution measurement result, and the particle size (median diameter) at 50% in the cumulative curve of the obtained particle size distribution is taken as the average particle size.

[0019] By including 15 to 75 parts by mass, preferably 25 to 55 parts by mass, and more preferably 30 to 50 parts by mass of the above pigment with respect to 100 parts by mass of the total epoxy resin contained in the epoxy resin composition, good balance of light shielding properties and adhesion during manual coating of the resin cured product can be obtained.

[0020] Component [C] is a non-aromatic thermoplastic resin. Here, "aromatic" means those containing aromatic hydrocarbons or conjugated unsaturated heterocyclic compounds in the chemical structure, and the rest are "non-aromatic". That is, a non-aromatic thermoplastic resin refers to a thermoplastic resin that does not contain an aromatic hydrocarbon group or an unsaturated heterocycle in its chemical structure. Examples of non-aromatic thermoplastic resins include polyvinyl alcohol, polyvinyl acetal, polyvinyl formal, polyvinyl acetoacetal, polyvinyl butyral, polyvinyl acetate, hydrogenated bisphenol A·pentaerythritol phosphite polymer, hydrogenated terpene, hydrogenated terpene phenol, and the like.

[0021] Polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyvinyl acetoacetal, and polyvinyl acetate vinyl, which have particularly high solubility in non-aromatic epoxy resins, are preferred in that they can easily adjust the viscosity of the epoxy resin composition. Polyvinyl acetoacetal and polyvinyl butyral are more preferred because they can improve the elongation of the cured epoxy resin composition. Here, the elongation refers to the bending strain (%) when the cured epoxy resin composition is bent at three points in a predetermined shape.

[0022] These non-aromatic thermoplastic resins are preferably soluble in the epoxy resin of component [A]. For example, at least 10 parts by mass of the powder of the thermoplastic resin is added to 100 parts by mass of the epoxy resin of component [A], and kneaded at 100 to 120 ° C for 1 hour. As a result, if the weight loss of the powder of the thermoplastic resin is observed compared to the start, it is considered soluble. The observation of weight loss means that it becomes so small that it is optically unobservable, or when the remaining powder is recovered, a mass reduction of 10% or more is observed compared to the start. From the viewpoint of dissolving in the epoxy resin, the powder of the thermoplastic resin preferably has an average particle size of 100 μm or less obtained by at least the laser diffraction method. Also, if the average particle size is larger than 100 nm, it is preferable such as easy suppression of aggregation during storage and easy stirring into the epoxy resin.

[0023] In addition, when the molecular weights of these non-aromatic thermoplastic resins are 5000 to 70000 g / mol, preferably 7000 to 65000 g / mol, and more preferably 10000 to 60000 g / mol, a good balance between the uniformity of dissolution in the epoxy resin composition and the resin flow suppression effect can be obtained. Here, the molecular weight means the weight average molecular weight in terms of polystyrene by gel permeation chromatography using HLC-8420GPC (manufactured by Tosoh Corporation).

[0024] As the above non-aromatic thermoplastic resin, commercially available products can be used. For example, "J-POVAL (registered trademark)" (manufactured by Nippon Vinyl Poval Co., Ltd.), "Vinylec (registered trademark)" (manufactured by JNC Corporation), "Esrec (registered trademark)" (manufactured by Sekisui Chemical Co., Ltd.), "Ultracent (registered trademark)" (manufactured by Tosoh Corporation), JPH-3800 (manufactured by Johoku Chemical Co., Ltd.), YS Polyster UH130 (manufactured by Yasuhara Chemical Co., Ltd.), etc.

[0025] When the epoxy resin composition is applied as a spray, by containing 0.05 parts by mass or more of the above non-aromatic thermoplastic resin with respect to 100 parts by mass of all the epoxy resins contained in the epoxy resin composition, a resin flow suppression effect can be obtained. Here, the spray refers to a method of filling the epoxy resin composition in a container and spraying the epoxy resin composition in a mist or foam form by using high-pressure air or mechanical movement through a nozzle. When the epoxy resin composition is applied as a spray, it is preferable to contain 0.05 to 1 part by mass, preferably 0.1 to 0.5 part by mass of the above non-aromatic thermoplastic resin, because it can keep the spraying amount per unit time large and obtain a high resin flow suppression effect.

[0026] Also, when the epoxy resin composition is applied by hand coating, by containing 1 to 75 parts by mass or less, preferably 5 to 65 parts by mass, more preferably 10 to 55 parts by mass of the above non-aromatic thermoplastic resin with respect to 100 parts by mass of all the epoxy resins, good adhesion can be obtained. Here, the hand coating refers to, for example, a method of storing the epoxy resin composition in a container, dipping a brush or roller into the epoxy resin composition and then applying it to the target by hand with the brush or roller, or a method of placing the epoxy resin composition on the target and spreading it using a spatula or a bar coater.

[0027] The component [D] is a cationic curing agent or an anionic curing agent. Examples of cationic curing agents include 1-naphthylmethylmethyl p-hydroxyphenylsulfonium hexafluoroantimonate, 2-methylbenzylmethyl p-hydroxyphenylsulfonium hexafluoroantimonate, benzylmethyl p-hydroxyphenylsulfonium hexafluoroantimonate, dimethyl-p-acetoxyphenylsulfonium hexafluoroantimonate, diaryliodonium salts, boron trifluoride piperidine, boron trifluoride monoethylamine, diaryliodonium salts, sulfonium salts, and the like.

[0028] Commercially available products can be used as the above cationic curing agents. For example, "ADEKA OPTON (registered trademark)" CP-77, "ADEKA OPTON (registered trademark)" CP-66 (manufactured by ADEKA CORPORATION), CI-2639, CI-2624 (manufactured by Nippon Soda Co., Ltd.), "SUN-AID (registered trademark)" SI-60, "SUN-AID (registered trademark)" SI-80, "SUN-AID (registered trademark)" SI-100, "SUN-AID (registered trademark)" SI-150, "SUN-AID (registered trademark)" SI-B4, "SUN-AID (registered trademark)" SI-B5 (manufactured by Sanshin Chemical Industry Co., Ltd.), TA-100, IK-1PC(80) (manufactured by San-Apro Ltd.), boron trifluoride piperidine, boron trifluoride monoethylamine (manufactured by Stella Chemifa Corporation), and the like. The cationic curing agent is preferably a photo-thermal cationic curing agent or a thermal cationic curing agent. A photo-thermal cationic curing agent refers to one that generates reactivity by applying light with a certain wavelength or less such as ultraviolet rays or visible light or heat at a certain temperature or higher, and a thermal cationic curing agent refers to one that generates reactivity by heat. Using a photo-thermal cationic curing agent is preferable because it can be cured in a variety of environments, and in the case of a thermal cationic curing agent, high storage stability can be obtained by temperature control, so it is preferable.

[0029] Examples of anionic curing agents include phosphorus hexafluoride, antimony hexafluoride, arsenic hexafluoride, tin hexachloride, iron tetrachloride, bismuth pentachloride, niobium hexachloride, and the like.

[0030] By using at least two types of the above-mentioned curing agents, the reactivity of the epoxy resin composition can be controlled, and a good balance between the rapid curability and the pot life of the epoxy resin composition can be obtained.

[0031] The reactivity of the coating agent composed of the epoxy resin composition can be controlled by the type and addition amount of the above-mentioned curing agent. When the coating agent composed of the epoxy resin composition is applied to a fiber-reinforced composite material precursor such as a prepreg and molded, during the molding process, the epoxy resin composition cures faster than the resin of the fiber-reinforced composite material precursor, and after the curing of the epoxy resin composition, the resin of the fiber-reinforced composite material precursor does not mix into the epoxy resin composition. Therefore, it is preferable in that a high inhibitory effect on the amount of the resin of the fiber-reinforced composite material precursor mixed into the epoxy resin composition can be obtained. Here, the DSC exothermic peak temperature of the coating agent depends on the curing temperature of the fiber-reinforced composite material precursor, but it is preferably 40°C or more lower than the curing temperature of the fiber-reinforced composite material precursor, and more preferably 60°C or more lower. When the curing temperature of the fiber-reinforced composite material precursor is 180°C, it is also preferable from the viewpoint of handleability that the DSC exothermic peak temperature of the coating agent is in the range of 80 to 120°C.

[0032] The above-mentioned curing agent contains 0.5 to 10 parts by mass, preferably 1 to 5 parts by mass, more preferably 1 to 3 parts by mass, based on 100 parts by mass of all epoxy resins contained in the epoxy resin composition, so that it has rapid curability and can obtain a good balance between resin flow and volatile amount suppression effect, rapid curability, pot life and UV resistance during molding.

[0033] In addition, the epoxy resin composition in the present invention can contain a thixotropy-imparting agent as a component [E]. Examples of the thixotropy-imparting agent include silicon dioxide, magnesium silicon sodium fluoride hydroxide oxide, alkyl quaternary ammonium salts, synthetic hectorite, viscous minerals, modified bentonite, and a mixed system of minerals and organically modified bentonite.

[0034] The above thixotropy-imparting agent can be a commercially available product. Examples include fumed silica ("Aerosil (registered trademark)" (manufactured by Nippon Aerosil Co., Ltd.)), "OPTIGEL (registered trademark)", "OPTIBENT (registered trademark)", "GARAMITE (registered trademark)", "LAPONITE (registered trademark)", "TIXOGEL (registered trademark)", "CRAYTONE (registered trademark)", "CLOISITE (registered trademark)" (manufactured by BYK Co., Ltd.)), "Somasif (registered trademark)" ME-100, micro mica MK (manufactured by Katakura Koppu Agri Co., Ltd.), and the like.

[0035] By containing the above thixotropy-imparting agent in preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the total epoxy resin contained in the epoxy resin composition, a good balance between the resin flow suppression effect during molding and the adhesion characteristics can be obtained.

[0036] Furthermore, the epoxy resin composition in the present invention can contain a curing aid as component [F]. Examples of the curing aid include 4-hydroxyphenyldimethylsulfonium methyl sulfate, 4-(methylthio)phenol, and the like.

[0037] The above curing aid can be a commercially available product. Examples include "Sun-Aid (registered trademark)" SI-S, "Sun-Aid (registered trademark)" S-ME (manufactured by Sanshin Chemical Industry Co., Ltd.), and the like.

[0038] By containing the above curing aid in preferably 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.1 to 2.5 parts by mass with respect to 100 parts by mass of the total epoxy resin contained in the epoxy resin composition, a good balance between the rapid curability and the pot life of the epoxy resin composition can be obtained.

[0039] The epoxy resin composition in the present invention can contain rubber as component [G]. Examples of the rubber include natural rubber, diene rubber, non-diene rubber, etc. Examples of the diene rubber include styrene-butadiene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, etc. Examples of the non-diene rubber include butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, urethane rubber, silicone rubber, fluorine rubber, etc. Among the contents in the epoxy resin composition in the present invention, even if non-diene rubber is not preferred, ethylene-propylene rubber, ethylene-propylene-diene rubber, silicone rubber, and fluorine rubber, which do not have double bonds in the polymer main chain, have high light resistance and are particularly preferred because they have little influence on the UV resistance of the epoxy resin composition in the present invention. Also, as the shape of the rubber, a powder form is particularly preferred because it has excellent dispersibility in the epoxy resin composition.

[0040] When the epoxy resin composition is applied as a spray, by containing the above rubber in an amount of 0.05 parts by mass or more with respect to 100 parts by mass of the total epoxy resin contained in the epoxy resin composition, the resin flow suppression effect and the elongation of the cured epoxy resin composition are excellent, so that the effect of preventing cracking after coating can be obtained. Here, the elongation refers to the bending strain (%) when the cured epoxy resin composition is bent at three points in a predetermined shape, and the spray refers to a method of filling the epoxy resin composition in a container and spraying the epoxy resin composition in a mist or foam form by using a nozzle and high-pressure air or mechanical movement. It is preferable to contain the above rubber in an amount of preferably 0.05 to 1 part by mass with respect to 100 parts by mass of the total epoxy resin contained in the epoxy resin composition because the spraying amount per unit time can be kept large and a high resin flow suppression effect can be obtained.

[0041] Also, when the epoxy resin composition is applied by manual coating, the content of the above rubber is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the total epoxy resin. When the content of the rubber is 1 part by mass or more with respect to 100 parts by mass of the total epoxy resin, the resin flow suppression effect and the elongation of the epoxy resin composition after curing are excellent, so that the effect of preventing cracks after coating can be obtained, which is preferable. When it is 50 parts by mass or less, the adhesion to the target epoxy resin composition is excellent, which is preferable. Here, the manual coating refers to, for example, a method of storing the epoxy resin composition in a container, dipping a brush or a roller into the epoxy resin composition, and then applying it to the target by hand with the brush or the roller, or a method of placing the epoxy resin composition on the target and spreading it using a spatula or a bar coater.

[0042] Commercially available products can be used as the above rubber. Examples include KMP-598, KMP-600, KMP-601, KMP-602, KMP-605 (manufactured by Shin-Etsu Chemical Co., Ltd.), "Cebian (registered trademark)" (manufactured by Daicel Miraiz Co., Ltd.), JSR N215SL, JSR N222SH, JSR N238H, JSR N241H, JSR N250S, PN30A, PN20HA, N280 (manufactured by JSR Corporation), and the like.

[0043] The coating agent for spraying or manual coating comprising the epoxy resin composition of the present invention preferably has a volatile content of 10% or less after being placed in an environment of 180 °C for 1 hour from the viewpoints of work environmental properties and accurate control of the thickness after molding.

[0044] It is preferable from the viewpoint of UV resistance that no discoloration is observed after irradiating the cured product of the epoxy resin composition according to the present invention with UV having a wavelength of 300 to 400 nm at 1000 kJ / m 2 and it is possible to protect the coating target from UV. The fact that no discoloration is observed indicates that in the present invention, the difference ΔE*ab between before and after UV irradiation is 4 or less, Color and the difference ΔE*ab can be obtained by measuring the colorimetric values of the cured product of the epoxy resin composition before and after irradiation with ultraviolet rays having a wavelength of 300 to 400 nm at 1000 kJ / m Color using a multi-source spectrophotometer. 2 ​

[0045] The coating agent for spraying or manual painting comprising the epoxy resin composition of the present invention can be cured by heat after being applied to the metal surface, or can be applied to the outermost surface of an uncured prepreg, RTM material, or resin film infusion (RFI) material (also referred to as "fiber-reinforced composite material precursor" in the present invention) generally used for fiber-reinforced composite materials, and can be cured together by heat in the applied state. Here, the prepreg is a fiber-reinforced composite material precursor obtained by impregnating reinforcing fibers with a thermosetting resin such as an epoxy resin, the RTM material is a fiber-reinforced composite material precursor obtained by laminating a reinforcing fiber base material in a mold and injecting a liquid thermosetting resin thereinto to impregnate the reinforcing fiber base material, and the RFI material refers to a fiber-reinforced composite material precursor obtained by stacking and laminating a thermosetting resin film on a reinforcing fiber base material and impregnating the reinforcing fiber base material with the thermosetting resin by heating and pressing. When applying to the surface of a metal, a silane coupling agent may be applied to the surface of the metal before application, treated with a light source or heat, and then the epoxy resin composition may be applied to the metal surface. By the treatment with the silane coupling agent, the silane coupling agent serves as a bridge between the metal surface and the coating agent of the epoxy resin composition in the present invention, and the effects of improving the adhesiveness between the metal surface and the coating agent and improving the wettability of the coating agent to the metal surface can be obtained. By curing, the cured product of the epoxy resin composition covers the surface of the fiber-reinforced composite material precursor after curing, and a fiber-reinforced composite material integrated therewith can be obtained.

[0046] As the reinforcing fibers in the fiber-reinforced composite material precursor, various carbon fibers, graphite fibers, glass fibers, aramid fibers, etc. are preferably used.

[0047] The coating agent for spraying or manual application composed of the epoxy resin composition of the present invention is applied to a fiber-reinforced composite material precursor and exhibits its effects by thermosetting together. However, the epoxy resin composition may be applied by spraying, or may be manually applied using a brush or the like or a bar coater. Further, after manual application, evacuation using a release film or the like can enhance the adhesion between the coating agent for spraying or manual application composed of the epoxy resin composition of the present invention and the fiber-reinforced composite material precursor.

[0048] The epoxy resin composition according to the present invention can be applied to an object in various ways. For example, a method of filling the epoxy resin composition into a container and spraying the epoxy resin composition in a mist or foam form by using high-pressure air or mechanical movement with a nozzle, or dipping a roller or a brush into the coating agent of the present invention and applying it to the object is also possible. Further, it is also possible to apply the coating agent of the present invention by using a bar coater or a spatula. In any method, it is also possible to heat as necessary and apply while reducing the viscosity of the epoxy resin composition to a low viscosity.

[0049] As described above, the coating agent for spraying or manual application composed of the epoxy resin composition of the present invention can be applied to an object in various ways, but the preferred coating method depends on the room temperature viscosity of the epoxy resin composition. When the room temperature viscosity of the epoxy resin composition is 100 to 500 mPa·s, spraying is preferred. In the case of spraying, when the room temperature viscosity is 100 mPa·s or less, the resin flow at room temperature can be suppressed, and the thickness of the coating agent can be kept uniform. On the other hand, when the room temperature viscosity is 500 m·Pa or less, the epoxy resin composition does not clog during spraying and can be applied, and the workability is good.

[0050] When the room temperature viscosity of the epoxy resin composition is 0.5 to 30 Pa·s, manual application using a roller or a brush or the like is preferred. If the room temperature viscosity of the epoxy resin composition is 0.5 Pa·s or more, sagging during application can be suppressed, which is preferable. When it is 30 Pa·s or less, the workability is good because a brush or a roll can be easily dipped into the epoxy resin composition.

[0051] When the room temperature viscosity of the epoxy resin composition is 30 to 30,000 Pa·s, coating by manual coating using a spatula, a bar coater, etc. is preferable. In the case of coating by manual coating, when the room temperature viscosity of the epoxy resin composition is 30 Pa·s or more, it is preferable because the resin flow inhibition effect of the epoxy resin composition during the curing process is high. Also, when the room temperature viscosity of the epoxy resin composition is 30,000 Pa·s or less, the adhesion between the epoxy resin composition and the fiber reinforced composite material precursor is high, and the adhesion between the cured epoxy resin composition and the fiber reinforced composite material is high, so it is preferable.

[0052] When applying the coating agent for spraying or manual coating composed of the epoxy resin composition of the present invention to the fiber reinforced composite material precursor, the basis weight is preferably 30 to 300 g / m 2 It is preferable that it is. When the basis weight of the epoxy resin composition is 30 g / m 2 or more, the surface of the fiber reinforced composite material can be covered without being seen through by the naked eye, and sufficient light resistance can be exhibited. Also, when the basis weight of the epoxy resin composition is 300 g / m 2 or less, it is preferable because the heat generation during curing of the epoxy resin composition can be suppressed when molding with the fiber reinforced composite material.

[0053] As the coating agent for spraying or manual coating composed of the epoxy resin composition of the present invention and the molding method of the fiber reinforced composite material, after applying to the outermost surface of the fiber reinforced composite material precursor, it is preferable to cure them together. The coating agent composed of the epoxy resin composition of the present invention described above is applied to the outermost surface of the fiber reinforced composite material precursor in a predetermined form, and is pressurized and heated to cure the coating agent composed of the epoxy resin composition of the present invention and the resin contained in the fiber reinforced composite material precursor, whereby a fiber reinforced composite material can be produced. Here, as the method of applying heat and pressure, for example, a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, an internal pressure molding method, etc. are adopted.

Examples

[0054] Hereinafter, the present invention will be described in detail with reference to examples. However, the scope of the present invention is not limited to these examples. Also, the measurement of various properties was carried out under an environment of a temperature of 23 °C and a relative humidity of 50% unless otherwise noted.

[0055] <Materials Used in Examples and Comparative Examples> (1) Aromatic Epoxy Resin · Bisphenol A type epoxy resin (“jER (registered trademark)” 828, manufactured by Mitsubishi Chemical Corporation), epoxy equivalent: 175 (g / eq.).

[0056] (2) Component [A] Non - aromatic Epoxy Resin · (3’,4’ - Epoxycyclohexane)methyl 3,4 - epoxycyclohexanecarboxylate (“Celoxide (registered trademark)” 2021P, manufactured by Daicel Corporation), epoxy equivalent: 136 (g / eq.) · Adduct of 1,2 - epoxy - 4 - (2 - oxiranyl)cyclohexane with 2,2 - bis(hydroxymethyl)-1 - butanol (“EHPE3150”, manufactured by Daicel Corporation) · Epoxidized butanetetracarboxylic acid tetrakis-(3 - cyclohexenylmethyl) modified epsilon - caprolactone (“Epolide (registered trademark)” GT401, manufactured by Daicel Corporation) · Diglycidyl ether of 2,2 - bis(4 - hydroxycyclohexyl)propane (YX8000, manufactured by Mitsubishi Chemical Corporation).

[0057] (3) Component [B] Pigment · Titanium oxide (rutile type) (“Ti - Pure (registered trademark)” R - 960, manufactured by Kemira Corporation, average particle size 0.5 μm).

[0058] (4) Component [C] Non - aromatic Thermoplastic Resin · Polyvinyl formal (“Vinylec (registered trademark)” K, manufactured by JNC Corporation, calculated molecular weight 40000 - 54000 g / mol) · Polyvinyl formal (“Vinylec (registered trademark)” E, manufactured by JNC Corporation, calculated molecular weight 95000 - 134000 g / mol) · Polyvinyl acetal (“Esrec (R)” KS-10, manufactured by Sekisui Chemical Co., Ltd., calculated molecular weight 17000 g / mol) · Polyvinyl butyral (“Esrec (R)” BX-L, manufactured by Sekisui Chemical Co., Ltd., calculated molecular weight 18000 g / mol).

[0059] (5) Component [D] Cationic curing agent · Dimethyl-p-acetoxyphenylsulfonium hexafluoroantimonate “Sun-Aid (R)” SI-150, manufactured by Sanshin Chemical Industry Co., Ltd.) · Benzylmethyl p-hydroxyphenylsulfonium hexafluoroantimonate “Sun-Aid (R)” SI-100, manufactured by Sanshin Chemical Industry Co., Ltd.).

[0060] (6) Component [E] Thixotropy-imparting agent · Fumed silica (“AEROSIL (R)” RY200S, manufactured by Nippon Aerosil Co., Ltd.) · Alkylammonium clay (“GARAMITE (R)” 1958, manufactured by BYK Co., Ltd.).

[0061] (7) Component [F] Curing aid · 4-Hydroxyphenyldimethylsulfonium = methyl sulfate (“Sun-Aid (R)” SI-S, manufactured by Sanshin Chemical Industry Co., Ltd.) · 4-(Methylthio)phenol (“Sun-Aid (R)” S-ME, manufactured by Sanshin Chemical Industry Co., Ltd.).

[0062] (8) Component [G] Rubber · Silicone rubber powder (KPM-601, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0063] <Epoxy resin composition, method for producing fiber-reinforced composite material, and evaluation method> The epoxy resin compositions of each example and comparative example were measured by the following method.

[0064] (1) Preparation of epoxy resin composition The epoxy resin corresponding to component [A] described in Tables 1 to 8 (including the aromatic epoxy resin in Examples 33 and Comparative Examples 1 and 8), the pigment corresponding to component [B], and if necessary, the thixotropy-imparting agent of component [E] and the rubber of component [G] were charged into a three-roll mill and mixed at an arbitrary roll rotation speed to obtain a powder mixture precursor. The powder mixture precursor and the non-aromatic thermoplastic resin corresponding to component [C] described in Tables 1 to 8 were charged into a mixer, and heat mixing was performed to dissolve the non-aromatic thermoplastic resin. Then, while continuing the kneading, the temperature was lowered to 60°C or lower, and the cation curing agent of component [D] described in Tables 1 to 8 and, if necessary, the curing aid of component [F] were added and stirred to obtain an epoxy resin composition.

[0065] (2) Measurement of the room temperature viscosity of the epoxy resin composition Using a dynamic viscoelasticity apparatus ARES-2KFRTN1-FCO-STD (manufactured by TA Instruments), the room temperature viscosity of the epoxy resin composition prepared in (1) above was measured. A parallel plate of a flat plate with a diameter of 40 mm was used for the upper and lower measurement jigs. After setting the epoxy resin composition so that the distance between the upper and lower jigs was 1 mm, it was measured in torsion mode (measurement frequency: 0.5 Hz) at an isothermal measurement temperature of 23°C for 10 minutes. The average value of the viscosity from 2 to 10 minutes of the measurement time was taken as the room temperature viscosity of the epoxy resin composition.

[0066] (3) Measurement of the pot life of the epoxy resin composition Using a dynamic viscoelasticity apparatus ARES-2KFRTN1-FCO-STD (manufactured by TA Instruments), the viscosity of the epoxy resin composition prepared in (1) above was measured. A parallel plate of a flat plate with a diameter of 40 mm was used for the upper and lower measurement jigs. After setting the epoxy resin composition so that the distance between the upper and lower jigs was 1 mm, it was measured in torsion mode (measurement frequency: 0.5 Hz). The viscosity η when held at 65°C for 2 minutes * 2. Held at 65°C for 2 hours, and the viscosity η at an arbitrary time * x was measured, and the thickening ratio at that time was η * x ÷η *It was determined from 2. The time until the obtained thickening magnification reached 3 was defined as the pot life.

[0067] (4) Measurement of the volatile content of the epoxy resin composition On a release paper (mass: W1), 3 g of the epoxy resin composition prepared in (1) above was weighed (mass: W2), and the epoxy resin composition and the release paper were placed in an oven at 180°C for 1 hour. Then, the epoxy resin composition and the release paper were taken out of the oven, left in a desiccator for 30 minutes, and then the combined mass of the epoxy resin and the release paper was measured (mass: W3). It was calculated as the volatile content [%] in the present invention by the following calculation formula. {(W2 - (W3 - W1)} / W2 × 100 [%] When the calculated volatile content was 5% or less, it was regarded as "good", and when it exceeded 5%, it was regarded as "bad".

[0068] (5) Measurement of the resin flow amount of the epoxy resin composition On a release film cut into a 15 cm square, 3 g of the epoxy resin composition prepared in (1) above was weighed (mass: W4). The epoxy resin composition was sandwiched with another release film cut into a 15 cm square, and further sandwiched with two 10 cm square metal plates (one plate weighing 400 g), and in that state, it was molded in an autoclave (at 6 atm, 180°C for 2 hours, heating rate 1.7°C / min). After molding, the cured product of the epoxy resin composition that protruded from the 10 cm square metal plate was removed, and the mass of the remaining cured product of the epoxy resin composition was measured (mass: W5). The resin flow amount [%] of the epoxy resin composition in the present invention was calculated by the following calculation formula. (W4 - W5) / W4 × 100 [%] The resin flow amount of 5% or less was designated as A, more than 5% and 10% or less as B, more than 10% and 15% or less as C, and more than 15% as D.

[0069] (6) Adhesion of the epoxy resin composition The epoxy resin composition prepared in (1) above was applied to an aluminum plate of any size (larger than 10 cm square) so that the thickness of the epoxy resin composition was 80 μm, and a 10 cm square stainless steel plate (400 g) that had been subjected to a release treatment by spraying Die Free GA-3000 (manufactured by Daikin Industries, Ltd.) from above was placed on it and held for 30 seconds. Then, the stainless steel plate was lifted, and with the epoxy resin composition adhering to the aluminum plate, the aluminum plate was leaned against the ground so as to be at 90°, and after 24 hours, if the epoxy resin composition adhered to the aluminum plate, the adhesion was rated as "good", and if there was any peeling even in part, it was rated as "poor".

[0070] (7) UV irradiation test of the epoxy resin composition The epoxy resin composition prepared in (1) above was applied onto a release film so that the epoxy resin composition had a thickness of 80 μm, cured in an oven at 180 °C for 2 hours under the condition of a temperature increase of 1.7 °C / min, and with half of the surface of the cured product of the obtained epoxy resin composition covered with aluminum foil, using a metal halide weather meter (M6T, manufactured by Suga Test Instruments Co., Ltd.), the irradiation wavelength was set to 300 to 400 nm, and the integrated illuminance was set to 1.55 kW / m 2 Since it is assumed that the cured product of the epoxy resin composition of the present invention will be exposed to sunlight outdoors on an annual basis, the integrated intensity of 1000 kJ / m 2 of UV light, which is an approximate value of the UV amount for one month in Japan (summer), was irradiated. After irradiation, the aluminum foil was peeled off, and the appearance of the place covered with the aluminum foil and the place not covered with it was visually observed with the naked eye to confirm the presence or absence of discoloration of the epoxy resin cured product before and after UV irradiation. The color difference of the cured product of the epoxy resin composition before and after irradiation was measured using a multi-source spectrophotometer (MSC-P, manufactured by Suga Test Instruments Co., Ltd.). The epoxy resin composition was set in the multi-source spectrophotometer, and as the measurement conditions, in the wavelength range of 380 to 780 nm, the reflectance was measured under the conditions of reflection mode, C light source, 2° field of view, and 8° incidence. Furthermore, using the program attached to the device, L * a * b * The colorimetric values (L * 1a * 1b * 1) before UV irradiation in the color change system were determined. Next, after the UV irradiation was carried out (L* 2a * 2b * 2) was determined. Furthermore, the color difference ΔE * ab of the cured product of the epoxy resin composition before and after UV irradiation * ab = [(L * 1 - L * 2) 2 + (a * 1 - a * 2) 2 + (b * 1 - b * 2) 2 ) 1 / 2 was determined. When the obtained ΔE * ab is 4 or less, the UV resistance is rated as "good", and when ΔE * ab exceeds 4, the UV resistance is rated as "poor".

[0071] (8) Resin amount of prepreg mixed into the epoxy resin composition during the molding process The epoxy resin composition prepared in (1) above was laminated in 8 layers (lamination structure: [+45° / 0° / -45° / 90°] s ) so as to be pseudo-isotropic with a continuous fiber prepreg (T800S / 3900-2B (manufactured by Toray Industries, Inc.)), and the epoxy resin composition was applied to the outermost surface so as to have a thickness of 80 μm. In this state, the cured product side of the composite material molded in an autoclave under the conditions of 6 atm, 180 °C for 2 hours, and a heating rate of 1.7 °C / min was measured by IR measurement using the ATR method (FT / IR-4000 manufactured by JASCO Corporation, prism: diamond, measurement wavelength: 400~4000 cm -1 , integration times: 16 times). Normalization was performed using the peak at 1715 cm -1 indicating ester, and by evaluating the value of the peak at 1592 cm -1 indicating the benzene ring due to the resin cured product used in the prepreg, it becomes possible to evaluate the amount of the resin used in the prepreg mixed with the coating agent composed of the epoxy resin composition during the molding process and exposed to the surface of the fiber-reinforced composite material. The benzene ring due to the resin cured product used in the prepreg is shown at 1592 cm -1If the peak value is 0.6 or less, it was determined that the UV resistance of the surface of the fiber-reinforced composite material was good. Also, in Examples 35 to 56 and Comparative Examples 9 to 11, IR measurement by the ATR method was carried out in the same manner as above, and normalization using the peak at 1715 cm -1 indicating an ester was not performed, and the peak value at 1592 cm -1 indicating the benzene ring due to the resin cured product used in the prepreg was evaluated. In this case, if the peak value at 1592 cm -1 indicating the benzene ring due to the resin cured product used in the prepreg was 1.0 or less, it was determined that the UV resistance of the surface of the fiber-reinforced composite material was good.

[0072] (9) Method for applying the epoxy resin composition to the prepreg surface When applying the epoxy resin composition by spraying, the epoxy resin composition was spray-coated onto the prepreg surface using a spray gun W-2001-2 (manufactured by Anest Iwata Corporation).

[0073] When applying the epoxy resin composition by hand using a brush, the epoxy resin composition was stored in a container, the brush was immersed therein, and then directly applied to the target.

[0074] When applying the epoxy resin composition by hand using a bar coater, the epoxy resin composition was placed on the surface of the application target and spread with the bar coater and applied to the target.

[0075] (10) Method for measuring the exothermic peak temperature of the epoxy resin composition Using a differential scanning calorimeter (DSC Q2500, manufactured by TA Instruments), the exothermic curve of the epoxy resin composition was obtained in a nitrogen atmosphere at a heating rate of 5°C / min. In the obtained exothermic curve, the temperature at the peak of the exothermic peak with an exothermic amount of 100 mW / g or more was calculated as the exothermic peak temperature. When there are two or more exothermic peaks with an exothermic amount of 100 mW / g or more, the temperature at the peak of the peak on the low-temperature side was calculated as the exothermic peak temperature of the DSC in the present invention. Regarding the evaluation of rapid curability, in Tables 1 to 4, an exothermic peak temperature of 100°C or less was denoted as A, more than 100°C and 120°C or less as B, more than 120°C and 140°C or less as C, and more than 140°C as D.

[0076] (11) Flexural test of the cured epoxy resin composition After degassing the uncured epoxy resin composition in vacuo, using a 2 mm thick spacer made of "Teflon (registered trademark)", it was set in a mold to a thickness of 2 mm and cured at a temperature of 180°C for 2 hours. The obtained epoxy resin cured product with a thickness of 2 mm was cut into a width of 10 ± 0.1 mm and a length of 60 ± 1 mm to obtain test pieces. Using an Instron universal testing machine (manufactured by Instron), three-point bending with a span of 32 mm was carried out in accordance with JIS-K7171 (1994), and the elastic modulus and flexural strain (elongation) were measured. The number of measurements was N = 6, and the average value was obtained.

[0077] <Examples 1 to 32 and Comparative Example 1> In Examples 1 to 32, as component [A], only (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate, or a combination of an aliphatic epoxy resin such as an adduct of 2,2-bis(hydroxymethyl)-1-butanol and 1,2-epoxy-4-(2-oxiranyl)cyclohexane or an epoxy-modified tetracarboxylic acid tetrakis-(3-cyclohexenylmethyl) modified epsilon-caprolactone was used for the epoxy resin composition. As a result, no discoloration was observed after curing in the UV resistance test, and good results were obtained. On the other hand, in Comparative Example 1 containing only an aromatic epoxy resin without containing an aliphatic epoxy resin as component [A], it was determined to be poor in the UV resistance test, indicating low UV resistance.

[0078] <Examples 1 to 2> In Examples 1 and 2, the types of component [D] were changed and compared. As a result, when benzylmethyl p - hydroxyphenylsulfonium hexafluoroantimonate was used as the cationic curing agent, the curing speed was higher than when an iodonium salt was used as the cationic curing agent, and there was a tendency to suppress all of the volatility, resin flow, and the resin amount of the prepreg mixed into the coating agent composed of the epoxy resin composition during the molding process. On the other hand, it was shown that the pot life decreased.

[0079] <Examples 2 to 6, 21 to 23, 26 to 28, 34, Comparative Examples 4 to 5> In Examples 2 to 3 where the coating method was spray, the types of component [C] were changed and compared. As a result, it was shown that when polyvinyl formal was used as compared with polyvinyl acetoacetal, the effect of suppressing the resin flow amount was higher. Also, in Examples 4 to 6 where the coating method was also spray, the addition amount of polyvinyl acetoacetal was changed respectively, and it was shown that the effect of suppressing the resin flow amount improved as the amount increased.

[0080] On the other hand, in Comparative Example 4 where component [C] was not included, the resin flow amount was large, and the resin amount of the prepreg mixed into the coating agent composed of the epoxy resin composition of the present invention during the molding process became excessive and was determined to be defective.

[0081] Also, in Examples 21 to 22 where the coating method was hand - coating using a brush and in Examples 23, 26 to 28 where the coating method was hand - coating using a bar coater, the amount of polyvinyl formal of component [C] was changed, and in these cases too, it was shown that the effect of suppressing the resin flow amount improved as the amount of component [C] increased.

[0082] On the other hand, in Example 28, when the amount of polyvinyl formal of component [C] was 75 parts by mass, good adhesion was shown. On the other hand, when the amount of polyvinyl formal was 80 parts by mass as in Comparative Example 5, the room - temperature viscosity was high and the adhesion was determined to be poor.

[0083] In Example 34, when Vinylec E (calculated molecular weight: 95,000 to 134,000 g / mol), which has a higher calculated molecular weight than Vinylec K (calculated molecular weight: 40,000 to 54,000 g / mol) and Esrec KS-10 (calculated molecular weight: 17,000 g / mol), was used as Component [C], a high resin flow suppression effect was shown, and an effect of suppressing the resin amount of the prepreg mixed into the resin cured product during the molding process was demonstrated. On the other hand, the room temperature viscosity was excessive and the adhesion was judged to be poor.

[0084] <Examples 23 to 25, 33, Comparative Example 8> In Example 23, 100 parts by mass of (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate was used as Component [A]. While in Example 24, 30 parts by mass of the 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol and in Example 25, 30 parts by mass of epoxybutanetetracarboxylic acid tetrakis-(3-cyclohexenylmethyl) modified epsilon-caprolactone were added to 70 parts by mass of (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate, respectively. As a result, the adhesion of the epoxy resin compositions in Examples 23 to 25 was good, and the UV resistance was also good. Therefore, it was shown that for non-aromatic epoxy resins, an epoxy resin composition with good physical properties can be obtained both when using one type of epoxy resin and when using two or more types of epoxy resins.

[0085] In addition, in Example 33, 90 parts by mass of a non-aromatic epoxy resin and 10 parts by mass of an aromatic epoxy resin were used in combination, and as a result of the UV resistance evaluation, it was judged to be good. Therefore, it was shown that in the case of an epoxy resin composition containing 10% by mass of an aromatic epoxy resin among epoxy resins, the UV resistance is good.

[0086] On the other hand, in Comparative Example 8, 80 parts by mass of a non-aromatic epoxy resin and 20 parts by mass of an aromatic epoxy resin were used in combination, and as a result of evaluating the UV resistance, it was determined to be defective. Therefore, it was shown that the UV resistance is poor in the case of an epoxy resin composition containing 20% by mass of an aromatic epoxy resin among the epoxy resins.

[0087] <Examples 1, 2, 7 to 10, Comparative Examples 6, 7> In Example 7, the amount of the iodonium salt, which is the cationic curing agent [D] component, was increased as compared with Example 1. While the rapid curability of the epoxy resin composition of Example 7 increased as compared with Example 1, the pot life decreased, but it was shown that the effect of suppressing the resin amount of the prepreg mixed into the coating agent composed of the epoxy resin composition of the present invention during the volatilization amount, resin flow amount, and molding process was high.

[0088] Similarly, in Example 8, the amount of benzylmethyl p-hydroxyphenylsulfonium hexafluoroantimonate, which is the cationic curing agent of component [D], was increased as compared with Example 2. The rapid curability of the epoxy resin composition of Example 8 increased as compared with Example 2, while the pot life decreased, but it was shown that the effect of suppressing the resin amount of the prepreg mixed into the coating agent composed of the epoxy resin composition of the present invention during the volatilization amount, resin flow amount, and molding process was high.

[0089] In Examples 9 to 10, two types of dimethyl-p-acetoxyphenylsulfonium hexafluoroantimonate and benzylmethyl p-hydroxyphenylsulfonium hexafluoroantimonate, which are the cationic curing agents of component [D], were used in combination as the curing agent. In Example 9, the rapid curability decreased as compared with Example 8, while an increase in pot life was observed. In Example 10, the amount of methyl-p-acetoxyphenylsulfonium hexafluoroantimonate was increased from Example 9. In Example 10, the rapid curability improved as compared with Example 9, and the pot life decreased. Therefore, it was shown that the balance between the rapid curability and pot life of the epoxy resin composition can be controlled by the addition ratio of the cationic curing agent [D] component and the mixing ratio in the case of adding two types.

[0090] In Comparative Example 6, 0.05 part of dimethyl-p-acetoxyphenylsulfonium hexafluoroantimonate, which is a component [D] cationic curing agent, was added. Comparative Example 6 had low rapid curability, and the volatile content and the resin amount of the prepreg mixed into the epoxy resin composition during the molding process were judged to be poor.

[0091] On the other hand, in Comparative Example 7, 15 parts by mass of benzylmethyl p-hydroxyphenylsulfonium hexafluoroantimonate was added. The rapid curability was high, but the pot life was significantly reduced. Also, the evaluation of the resin amount of the prepreg mixed into the coating agent composed of the epoxy resin composition during the molding process was judged to be poor. Further, in Comparative Example 7, after UV irradiation of 1000 kJ / m 2 The epoxy resin composition after curing was judged to be poor by the UV resistance test, indicating low UV resistance.

[0092] <Examples 11 to 12, Examples 29 to 30, Comparative Examples 2 and 3> In Examples 11 to 12, the amount of titanium oxide as component [B] was changed for comparison. As a result, Example 12 with a larger amount of titanium oxide had a lower rapid curability and an improved pot life compared to Example 11, indicating that the reactivity of the epoxy resin composition can be controlled by the amount of titanium oxide. Also, it was shown that Example 12 with a larger amount of titanium oxide had a higher effect of suppressing the resin amount of the prepreg mixed into the epoxy resin composition during the molding process than Example 11.

[0093] In Examples 29 to 30, the amount of titanium oxide as component [B] was 15 parts by mass and 75 parts by mass, respectively. Example 30 showed a lower rapid curability compared to Example 29 and a high effect of improving the suppression of the volatile content. Also, both of them were judged to have good UV resistance and the resin amount of the prepreg mixed into the epoxy resin composition during the molding process.

[0094] On the other hand, when the amount of titanium oxide as component [B] was 10 parts by mass as in Comparative Example 2, the resin amount of the prepreg mixed into the epoxy resin composition during the molding process was large and was judged to be poor.

[0095] Also, when 100 parts by mass of titanium oxide of component [B] was added as in Comparative Example 3, the rapid curability was poor, and the volatile content after 1 hour at 180°C was determined to be defective.

[0096] <Examples 8, 13 to 15, 23, 31> In Examples 13 to 15 where the coating method was spray, a curing aid of component [F] was applied. In Example 13, as a result of applying 0.2 part by mass of 4-hydroxyphenyldimethylsulfonium = methyl sulfate as the curing aid of component [F], an improvement in the pot life was observed compared to Example 8. Further, in Example 15, as a result of increasing the amount of 4-hydroxyphenyldimethylsulfonium = methyl sulfate to 1.0 part, a further improvement in the pot life was observed compared to Example 13. Similarly, in Example 14, the type of the curing aid of component [F] was changed to 4-(methylthio)phenol and 0.2 part was applied, and as a result, an improvement in the pot life was observed compared to Example 8. Also, Examples 13 to 15 were judged to be good in terms of volatility, UV resistance, and the resin amount of the prepreg incorporated into the coating agent composed of the epoxy resin composition during the molding process.

[0097] Also, in Example 31 where the coating method was hand coating using a bar coater, as a result of applying 0.2 part by mass of 4-hydroxyphenyldimethylsulfonium = methyl sulfate as component [F], an improvement in the pot life was observed compared to Example 23 where the coating method was also hand coating using a bar coater. Therefore, it was shown that the effect of improving the pot life can be obtained by applying component [F] to the epoxy resin composition regardless of the coating method.

[0098] <Examples 8, 16 to 18, 23, 32> Examples 16 to 18, where the coating method is spray, apply component [E], a thixotropy-imparting agent. In Examples 16 to 17, 4 parts each of fumed silica and alkylammonium clay are applied to Example 8, where the coating method is also spray. The effects of suppressing the resin flow amount and the resin amount of the prepreg incorporated into the epoxy resin composition during the molding process were shown without impairing rapid curability and UV resistance. Further, in Example 18, 4 parts each of fumed silica and alkylammonium clay are applied to Example 8, and it was shown that the effect of suppressing the resin flow amount and the resin amount of the prepreg incorporated into the epoxy resin composition during the molding process is higher as compared with Examples 16 to 17.

[0099] Also, in Example 32, where the coating method is hand coating using a bar coater and both fumed silica and alkylammonium clay are applied to component [E], it was shown that the effect of suppressing the resin flow amount and the resin amount of the prepreg incorporated into the epoxy resin composition during the molding process is high as compared with Example 23, which is also hand coating using a bar coater.

[0100] Therefore, it was shown that by applying component [E] to the epoxy resin composition regardless of the coating method, an effect of suppressing the resin flow amount and an effect of improving the resin amount of the prepreg incorporated into the epoxy resin composition during the molding process can be obtained.

[0101] <Examples 8, 19 to 20> In Examples 19 to 20, where the coating method is spray, both component [E], a thixotropy-imparting agent, and component [F], a curing aid, are applied. As compared with Example 8, where the coating method is also spray, the effects of suppressing the resin flow amount and the resin amount of the prepreg incorporated into the epoxy resin composition during the molding process were shown, and further, it was shown that the pot life is excellent. Therefore, it was shown that a synergistic effect can be obtained by using components [E] and [F] simultaneously.

[0102] Also, in Example 32 of manual coating using a bar coater as the coating method, when both Component [E] thixotropic agent and Component [F] curing aid were applied, there was also an inhibitory effect on the resin flow amount of Comparative Example 23 and the resin amount of the prepreg mixed into the epoxy resin composition during the molding process, which are also manual coatings using a bar coater. Furthermore, it was shown that the pot life was excellent.

[0103] Therefore, it was shown that by applying both Component [E] and Component [F] to the epoxy resin composition, not limited to the coating method, an inhibitory effect on the resin flow amount and an improvement effect on the resin amount of the prepreg mixed into the epoxy resin composition during the molding process can be obtained.

[0104] <Examples 8, 35 to 45, Comparative Examples 9 to 10> In Examples 35 to 37, diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane was used as the non-aromatic epoxy resin of Component [A], and polyvinyl formal, polyvinyl acetoacetal, and polyvinyl butyral were each used one type as the non-aromatic thermoplastic resin of Component [C]. A decrease in the elastic modulus and an improvement in the flexural strain were observed in the cured products of the epoxy resin compositions in the order of Examples 35, 36, and 37. Also, when comparing Example 35 with Example 8, the exothermic peak temperature was lower in Example 35 while showing a high pot life, indicating that the reactivity can be controlled by changing the type of Component [A]. Therefore, it was shown that the reactivity can be controlled by changing the type of Component [A], and the balance among rapid curability, pot life, i.e., the inhibitory effect on the resin flow amount during the molding process and the resin amount of the prepreg mixed into the resin cured product, and processability can be adjusted.

[0105] In Examples 38 to 39, silicone rubber powder of component [G] rubber was used. An increase in the content of component [G] showed a decrease in the elastic modulus of the cured product of the epoxy resin composition, an improvement in bending strain, and an effect of suppressing the resin flow amount. On the other hand, when the amount of component [G] was too small as in Comparative Example 9, the effect of suppressing the resin flow amount was not sufficiently exhibited, and the resin amount of the prepreg mixed with the resin cured product during the molding process became excessive and was judged as defective. Further, when the amount of component [G] was excessive as in Comparative Example 10, the epoxy resin composition clogged the nozzle during spraying and could not be applied.

[0106] In Examples 40 to 41, two types, (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate and diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane, were used as the non-aromatic epoxy resin of Component [A]. Comparing Examples 35, 40 to 41, it was shown that the higher the content of (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate, the lower the exothermic peak temperature, and the resin flow amount and the resin amount of the prepreg mixed into the resin cured product during the molding process were suppressed. Example 8 using only one type of (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate as Component [A] was excellent in fast curability, and Example 35 using only one type of diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane was shown to be excellent in pot life. When the above two types were used as in Examples 40 to 41, it became possible to achieve both excellent fast curability and excellent pot life. Therefore, it was shown that by using two types of non-aromatic epoxy resins of Component [A], the reactivity of the epoxy resin composition can be controlled, and the balance between the fast curability and the pot life, that is, the suppression effect of the resin flow amount and the resin amount of the prepreg mixed into the resin cured product during the molding process and the process passability can be adjusted. Here, comparing Examples 8 and 35, it was shown that the flexural strain of the epoxy resin cured product was higher in Example 35 using diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane than in Example 8 using (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate as the non-aromatic epoxy resin of Component [A]. Comparing Examples 40 to 41, it was shown that the higher the ratio of diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane used as the non-aromatic epoxy resin of Component [A], the higher the flexural strain of the epoxy resin cured product.

[0107] In Example 42, (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate was used in the non-aromatic epoxy resin of Component [A]. In Example 43, (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate and diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane were used. In both cases, 4-hydroxyphenyldimethylsulfonium = methyl sulfate was used as the curing aid of Component [F]. When comparing Example 42 with Example 35 and Example 43 with Example 41, it was shown that in Examples 42 and 43, the exothermic peak temperature was improved respectively, and the reactivity of the epoxy resin composition could be controlled by the inclusion of Component [F].

[0108] In Example 44, (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate was used in the non-aromatic epoxy resin of Component [A]. In Example 45, (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate and diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane were used. In both cases, fumed silica as the thixotropic agent of Component [E], 4-hydroxyphenyldimethylsulfonium = methyl sulfate as the curing aid of Component [F], and silicone rubber powder as the rubber of Component [G] were used. When comparing Example 44 with Example 35 and Example 45 with Example 41, it was shown that in Examples 44 and 45, the reactivity of the epoxy resin composition could be controlled by the inclusion of Component [F] respectively. Also, when comparing Example 44 with Example 42 and Example 45 with Example 43, it was found that in Examples 44 and 45, the resin flow amount was suppressed by the inclusion of Component [E] and Component [G], and the resin amount of the prepreg mixed into the resin cured product during the molding process was also suppressed. When comparing Example 44 with Example 35 and Example 45 with Example 41, it was shown that in Examples 44 and 45, the pot life of the epoxy resin composition was further improved by the inclusion of Component [F] respectively.

[0109] <Examples 23, 46 to 56, Comparative Example 11> In Examples 46 to 48, diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane was used as the non-aromatic epoxy resin of Component [A], and one kind each of polyvinyl formal, polyvinyl acetoacetal, and polyvinyl butyral was used as the non-aromatic thermoplastic resin of Component [C]. In the order of Examples 46, 47, and 48, an increase in room temperature viscosity, a decrease in the elastic modulus in the cured product of the epoxy resin composition, and an improvement in flexural strain were observed. Also, when Example 46 was compared with Example 23, the heat generation peak temperature was lower in Example 46, while it showed a higher pot life. Therefore, it was shown that the reactivity can be controlled by changing the type of Component [A], and the balance between rapid curability and pot life, that is, the suppression effect of the resin flow amount during the molding process and the suppression effect of the resin amount of the prepreg mixed in the resin cured product and the process passability can be adjusted.

[0110] In Examples 49 to 50, silicone rubber powder of Component [G] rubber was used. An increase in the content of Component [G] showed an increase in room temperature viscosity, a decrease in the elastic modulus of the cured product of the epoxy resin composition, an improvement in flexural strain, and an effect of suppressing the resin flow amount. On the other hand, when Component [G] was excessive as in Comparative Example 11, the room temperature viscosity also became excessive, and it was determined that the adhesiveness was poor.

[0111] In Examples 51 to 52, two types, (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate and diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane, were used for the non-aromatic epoxy resin of Component [A]. Comparing Examples 46, 51 to 52, it was shown that the higher the content of (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate, the lower the exothermic peak temperature, and the resin flow amount and the resin amount of the prepreg mixed into the resin cured product during the molding process were suppressed. Example 23 using only one type of (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate as Component [A] was excellent in rapid curability, and Example 46 using only one type of diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane was shown to be excellent in pot life. When using the above two types as in Examples 51 to 52, it is possible to achieve both excellent rapid curability and excellent pot life. Therefore, it was shown that by using two types of non-aromatic epoxy resins for Component [A], the reactivity of the epoxy resin composition can be controlled, and the balance between the rapid curability and the pot life, that is, the suppression effect of the resin flow amount and the resin amount of the prepreg mixed into the resin cured product during the molding process and the process passability can be adjusted. Here, comparing Examples 23 and 46, it was shown that the flexural strain of the epoxy resin cured product was higher in Example 46 using diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane than in Example 23 using (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate for the non-aromatic epoxy resin of Component [A]. Comparing Examples 51 to 52, it was shown that the higher the ratio of diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane used as the non-aromatic epoxy resin of Component [A], the higher the flexural strain of the epoxy resin cured product.

[0113] In Example 55, (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate was used as the non-aromatic epoxy resin of Component [A]. In Example 56, (3’,4’-epoxycyclohexane)methyl 3,4-epoxycyclohexanecarboxylate and diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane were used. In both cases, fumed silica as the thixotropic agent of Component [E], 4-hydroxyphenyldimethylsulfonium = methyl sulfate as the curing aid of Component [F], and silicone rubber powder of Component [G] were used. When comparing Example 55 with Example 46 and Example 56 with Example 52, Examples 55 and 56 showed the effect of further improving the pot life of the epoxy resin composition due to the inclusion of Component [F].

[0114]

Table 1

[0115]

Table 2

[0116]

Table 3

[0117]

Table 4

[0118]

Table 5

[0119]

Table 6

[0120]

Table 7

[0121]

Table 8

Claims

A coating agent for spraying or manual painting, which is composed of an epoxy resin composition containing at least constituent elements [A] to [E] and is used for the purpose of coating on the surface of a fiber-reinforced composite material precursor and thermosetting together. The coating agent contains 90 to 100 parts by mass of [A], 15 to 75 parts by mass of [B], 0.05 to 75 parts by mass of [C], 0.1 to 10 parts by mass of [D], and 0.5 to 10 parts by mass of [E] based on 100 parts by mass of the total epoxy resin. [A] Non-aromatic epoxy resin [B] Pigment with an average particle size of 0.1 to 10 μm [C] Non-aromatic thermoplastic resin [D] Cationic or anionic curing agent [E] Thixotropy-imparting agent

2. The coating agent according to claim 1, wherein the epoxy resin composition further contains a constituent element [F] curing aid.

3. The coating agent according to claim 2, wherein the constituent element [F] curing aid is 4-hydroxyphenyldimethylsulfonium methyl sulfate or 4-(methylthio)phenol.

4. The coating agent according to any one of claims 1 to 3, wherein the constituent element [C] non-aromatic thermoplastic resin is at least one selected from the group consisting of polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyvinyl acetoacetal, and polyvinyl acetate.

5. The coating agent according to any one of claims 1 to 4, wherein the DSC exothermic peak temperature is 80 to 120 °C.

6. The coating agent according to any one of claims 1 to 5, wherein the volatile content is 5% or less.

7. After irradiating the cured product of the epoxy resin composition with ultraviolet light having a wavelength of 300 to 400 nm at 1000 kJ / m ２ 2, the color difference ΔE ＊ The coating agent according to any one of claims 1 to 6, wherein the value of ab is 4 or less.

8. An intermediate substrate obtained by coating the surface of a fiber-reinforced composite material precursor using a thermosetting resin with the coating agent according to any one of claims 1 to 7.

9. A fiber-reinforced composite material obtained by coating the surface of a carbon fiber-reinforced composite material using a thermosetting resin with the cured product of the coating agent according to any one of claims 1 to 7.

10. A fiber-reinforced composite material obtained by coating the surface of a carbon fiber-reinforced composite material (excluding those for printed circuit assembly applications) using a thermosetting resin with the cured product of the coating agent according to any one of claims 1 to 7.

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