JP7158162B2 - EPOXY RESIN COMPOSITION, FIBER REINFORCED COMPOSITE MATERIAL AND MOLDED PRODUCT - Google Patents

Description

The present invention relates to an epoxy resin composition, more specifically, an epoxy resin composition obtained by blending a urethane-modified epoxy resin and cyanamide as a curing agent, and blending this with fibers such as glass, carbon, aramid, cloth, or non-woven fabric. The present invention relates to a fiber-reinforced composite material consisting of a material and a cured product thereof.

Epoxy resins are widely used in industrial fields such as paints, adhesives, electrical and electronic information materials, and advanced composite materials, taking advantage of their excellent mechanical properties. In particular, epoxy resins are frequently used in fiber-reinforced composite materials composed of reinforcing fibers such as carbon fibers, glass fibers, and aramid fibers and matrix resins.

As a method for manufacturing the fiber-reinforced composite material, a construction method such as a prepreg method, a hand lay-up method, a filament winding method, a pultrusion method, an RTM (Resin Transfer Molding) method, or the like is appropriately selected. Among these construction methods, the filament winding method, the pultrusion method, and the RTM method using liquid epoxy resin are particularly actively applied to industrial applications such as pressure vessels, electric wires, and automobiles.
Fiber reinforced composite materials used for pressure vessels are desired to have a high Vf (fiber content based on volume) in order to increase the strength of the pressure vessel. is desired to have a low Rc (resin content, resin content based on mass) compared to general prepregs. There is a problem that the matrix resin is likely to occur in areas where the matrix resin does not spread.

As a matrix resin for tow prepreg, an epoxy resin composition is mainly used as in general prepreg. Furthermore, as for the curing agent, it is common to use a particulate curing agent that is insoluble in epoxy resin at room temperature in order to maintain a long pot life like general prepreg (Patent Document 1, Patent Document 2). . Furthermore, addition of inorganic particles, thermoplastic resin particles, or the like is also frequently used in order to impart specific functions to the resin.
However, when such particles are used, the spacing between the single fibers of the reinforcing fiber tow is expanded by the particles, so that the amount of resin that can be contained in the reinforcing fiber tow increases, and the matrix resin is released from the surface of the reinforcing fiber tow. A phenomenon of migration to the inside of the reinforcing fiber tow is likely to occur. In addition, particles of the curing agent and the like are filtered into the fiber, resulting in a non-uniform state, which affects the functionality of the cured product.
Attempts have already been made to reduce the particle size of the curing agent used to address this phenomenon.
Special equipment such as a jet mill is required for manufacturing, which is costly and is not a fundamental solution (Patent Document 3).

Attempts have also been made to use liquid curing agents such as acid anhydrides and aromatic amines instead of particulate curing agents. However, when an acid anhydride is used as a curing agent, the resin composition is strongly affected by moisture in the air and thickened. This is because the acid anhydride reacts with water to change to a dicarboxylic acid, which then reacts with the epoxy resin. Therefore, an epoxy resin composition using an acid anhydride as a curing agent requires temperature control and moisture control, resulting in an increase in cost.

Aromatic amines are not affected by moisture as strongly as acid anhydrides, but since they react with epoxy resins at room temperature, they gel in a few days. In order to ensure the storage stability of the epoxy resin composition, it is essential to keep it under refrigeration, resulting in an increase in cost.
Furthermore, a method of blending cyanamide as a curing agent for epoxy resins (Patent Document 4) has been studied, but storage stability and blending into reinforcing fibers have not been studied.

Japanese Patent Application Laid-Open No. 09-87365 JP 2011-157491 A JP-A-2014-74130 JP 2016-44234 A

The present invention provides a cyanamide-containing epoxy resin composition that is liquid but has high storage stability. An improved epoxy resin composition for fiber reinforced composites is provided.

That is, the present invention provides an epoxy resin composition comprising a urethane-modified epoxy resin (A) and cyanamide (B) as essential components, wherein the urethane-modified epoxy resin (A) comprises an epoxy resin, a polyhydroxy compound (C) and a polyisocyanate. Using the compound (D) as a raw material, the total amount of the polyhydroxy compound (C) and the polyisocyanate compound (D) is 5 to 30% by weight with respect to the total amount of the urethane-modified epoxy resin (A), and cyanamide (B ) is 20 to 90% by weight based on the total amount of the structure derived from the polyhydroxy compound (C) and the polyisocyanate compound (D).
In this case, the viscosity at 25° C. measured using an E-type viscometer is preferably 5 to 80 Pa·s.

The present invention is a method for producing an epoxy resin composition containing a urethane-modified epoxy resin (A) and a cyanamide (B), comprising an epoxy resin (A1) having a secondary hydroxyl group, a polyhydroxy compound (C) and a poly Using the isocyanate compound (D), reacting raw materials in which the total amount of the polyhydroxy compound (C) and the polyisocyanate compound (D) is 5 to 30% by weight to obtain a urethane-modified epoxy resin (A), and then cyanamide. A method for producing an epoxy resin composition, characterized in that (B) is blended in an amount of 20 to 90% by weight based on the total amount of the polyhydroxy compound (C) and the polyisocyanate compound (D) used as the raw materials. .
In this case, among the polyhydroxy compounds (C), the equivalent ratio of hydroxyl groups in the polyhydroxy compounds having a number average molecular weight of 100 or less to isocyanate groups in the polyisocyanate compounds (D) is preferably 0.85 or less. be.

Another aspect of the present invention is a fiber-reinforced composite material comprising an epoxy resin composition blended with reinforcing fibers. It is preferable that the volume content of the reinforcing fibers is 30 to 75%.
Yet another aspect of the present invention is a molded article obtained by molding and curing the fiber-reinforced composite material by a filament winding method.

INDUSTRIAL APPLICABILITY The epoxy resin composition of the present invention has high storage stability while being liquid, and can improve the productivity of tow prepregs used particularly in the filament winding method.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.

The urethane-modified epoxy resin (A) used in the present invention is prepared by mixing a raw material epoxy resin having a hydroxyl group in the molecule, a polyhydroxy compound (C) such as polyether polyol or polyester polyol, and a polyisocyanate compound (D) with tin ( II) Obtained by heat reaction in the presence of a catalyst such as octoate. This urethane-modified epoxy resin may contain an unmodified epoxy resin that is not substantially bonded to polyurethane.

The urethane-modified epoxy resin (A), raw material epoxy resin (A1), cyanamide (B), polyhydroxy compound (C), and polyisocyanate compound (D) are also referred to as component (A) and component (B), respectively. Moreover, when each compounding amount or usage amount (parts by weight) is meant, it is represented by (A), (A1), (B), (C), and (D).
Urethane modification rate is defined by the following formula Urethane modification rate = [(C) + (D)] / (A) × 100

The urethane modification rate of the urethane-modified epoxy resin (A) is preferably 5 to 30% by weight, more preferably 7 to 25% by weight, from the viewpoint of viscosity and functionality. If it exceeds 30% by weight, the viscosity of the epoxy resin composition becomes high, and if it is lower than 5% by weight, sufficient functionality is not exhibited.

The urethane-modified epoxy resin (A) used in the present invention preferably has a viscosity measured using an E-type viscometer (cone plate type) at 25° C. in the range of 5 to 80 Pa s, more preferably 6 to 25 Pa. ·s, more preferably 7 to 20 Pa·s. As a result, the reinforcing fibers can be impregnated well, and the resin is less likely to drip from the fibers even after impregnation. Moreover, the urethane-modified epoxy resin (A) may be a mixture of several types, and the viscosity of the mixture is preferably within the above range.
The urethane-modified epoxy resin (A) preferably has an epoxy equivalent of 100 to 400 g/eq. More preferably 150-300 g/eq. is.

The epoxy resin (A1) used as a raw material for the urethane-modified epoxy resin (A) preferably has a hydroxyl equivalent of 1500 to 10000 g/eq, more preferably 1800 to 8000 g/eq. If the hydroxyl group equivalent is lower than 1500 g/eq, the viscosity of the urethane-modified epoxy resin is increased, and if it is higher than 10000 g/eq, the functionality of the cured product is lowered.

Specific examples of raw material epoxy resins (A1) include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, bisphenol Z type epoxy resin having two epoxy groups in one molecule. Resins, bisphenol-type epoxy resins such as isophorone bisphenol-type epoxy resins, halogen- and alkyl-substituted products of these bisphenol-type epoxy resins, hydrogenated products, high molecular weight products having multiple repeating units, and alkylene oxide additions Glycidyl ethers of substances, novolac epoxy resins such as phenol novolak epoxy resins, cresol novolak epoxy resins, bisphenol A novolac epoxy resins, and 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy- Alicyclic epoxy resins such as 6-methylcyclohexanecarboxylate, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 1-epoxyethyl-3,4-epoxycyclohexane, trimethylolpropane poly Aliphatic epoxy resins such as glycidyl ether, pentaerythritol polyglycidyl ether, and polyoxyalkylene diglycidyl ether; glycidyl esters such as diglycidyl phthalate, diglycidyl tetrahydrophthalate, and glycidyl dimer; and tetraglycidyl. Glycidylamines such as diaminodiphenylmethane, tetraglycidyldiaminodiphenylsulfone, triglycidylaminophenol, triglycidylaminocresol, and tetraglycidylxylylenediamine can be used. These may be used individually by 1 type, or may be used in combination of 2 or more type.

In the epoxy resin composition of the present invention, in addition to the urethane-modified epoxy resin (A), an unmodified ordinary epoxy resin may be added in an amount that does not impair its functionality, for example, less than 30% by weight of the total epoxy resin. can be done. Specifically, bisphenol A type epoxy resin having two epoxy groups in one molecule, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, bisphenol Z type epoxy resin, isophorone bisphenol type epoxy resin. Bisphenol-type epoxy resins such as bisphenol-type epoxy resins, halogen, alkyl-substituted products, hydrogenated products of these bisphenol-type epoxy resins, high molecular weight products having multiple repeating units not limited to monomers, glycidyl ethers of alkylene oxide adducts, and phenol Novolak type epoxy resins such as novolak type epoxy resins, cresol novolak type epoxy resins, bisphenol A novolac type epoxy resins, and 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate- 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 1-epoxyethyl-3,4-epoxycyclohexane and other alicyclic epoxy resins, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl Aliphatic epoxy resins such as ethers and polyoxyalkylene diglycidyl ethers, glycidyl esters such as diglycidyl phthalate, diglycidyl tetrahydrophthalate, and glycidyl dimer, tetraglycidyldiaminodiphenylmethane, tetraglycidyldiaminodiphenyl Glycidylamines such as sulfone, triglycidylaminophenol, triglycidylaminocresol, and tetraglycidylxylylenediamine can be used. These may be used individually by 1 type, or may be used in combination of 2 or more type.

Polyether polyols, polyester polyols and the like can be used as the polyhydroxy compound (C) which is a raw material of the urethane-modified epoxy resin (A).

As polyether polyols, low molecular weight polyhydric alcohols, amines, polyhydric phenols, compounds having two or more active hydrogens such as water are used as initiators, and lower alkylenes such as ethylene oxide, propylene oxide and butylene oxide are used. It is a product obtained by addition polymerization of a cyclic ether such as an oxide or tetrahydrofuran, and examples of low-molecular-weight polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, and 1,2-butanediol. , 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, hydrogenated bisphenol A, glycerin, trimethylolpropane, pentaerythritol and the like, and the above amines include ammonium , ethylenediamine, hexamethylenediamine, ethanolamine, propanolamine, and the like, and the polyhydric phenols include resorcin, hydroquinone, bisphenol A, bisphenol F, bisphenol S, and the like.

Examples of polyester polyols include condensates of low-molecular-weight polyhydric alcohols or polyether polyols with polycarboxylic acids, hydroxycarboxylic acids or carbonic acid, and ring-opening polymers of lactones. Examples of polycarboxylic acids include succinic acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, maleic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, and the like. Carboxylic acids include, for example, 12-hydroxystearic acid and castor oil fatty acids, and lactones include, for example, ε-caprolactam.

As the polyhydroxy compound (C), adducts of hydroxycarboxylic acids and alkylene oxides, polybutadiene polyols, polyolefin polyols, and the like can also be used.

The molecular weight of the polyhydroxy compound (C) is not particularly limited, but a weight average molecular weight in the range of 300 to 5000, particularly 500 to 2000 is used from the viewpoint of excellent balance between flexibility and curability. is preferred.

Examples of the polyisocyanate compound (D), which is a raw material for the urethane-modified epoxy resin (A), include aliphatic, alicyclic and aromatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, 1, 4-cyclohexane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,4-naphthalene diisocyanate, 1,5-naphthalene diisocyanate, 1,3 -phenylene diisocyanate, 1,4-phenylene diisocyanate, meta-xylylene diisocyanate, tetramethylxylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'-dimethyldiphenylmethane diisocyanate, 3,3'-dimethoxy-4,4' -biphenylene diisocyanate and the like, and these polyisocyanate compounds can be used alone or in combination of two or more. Among these, aromatic polyisocyanates are preferable, and 4,4'-diphenylmethane diisocyanate is particularly preferable because the resulting cured product has excellent mechanical properties.

Cyanamide (B) is used as a curing agent in the epoxy resin composition of the present invention. Cyanamide is a curing agent that is solid at room temperature, but dissolves in epoxy resin at room temperature to 50°C. In the present invention, a urethane-modified epoxy resin is contained as an essential component as the epoxy resin. The amount of cyanamide to be used is preferably in the range of 0.2 to 0.8 equivalents (calculated on the assumption that 1 mol of cyanamide is 2 equivalents) with respect to 1 equivalent of epoxy groups in the total epoxy resin. More preferably 0.2 to 0.6 equivalents. If the amount is less than 0.2 equivalents, the crosslink density of the cured product tends to be low and the fracture toughness tends to be low.

In the urethane-modified epoxy resin (A), hydrogen bonds are formed between urethane skeletons in the molecule, and it is considered that storage stability is exhibited by incorporating cyanamide therein. Therefore, the content of cyanamide (B) is 20 to 90% by weight based on the total amount of polyhydroxy compound (C) and polyisocyanate compound (D) forming the urethane skeleton. More preferably 30 to 80% by weight, still more preferably 35 to 75% by weight.
Here, the total amount of the polyhydroxy compound (C) and the polyisocyanate compound (D) is obtained by converting the structural units derived from these compounds present in the urethane-modified epoxy resin (A) into the amount of these compounds. is. The structural units derived from the polyhydroxy compound (C) and the polyisocyanate compound (D) correspond to the urethane structural units of the urethane-modified epoxy resin (A).
When the amount of cyanamide (B) exceeds 90% by weight, the cyanamide is not sufficiently incorporated and storage stability is not exhibited. be enough.

For urethane modification of the epoxy resin (A1), the equivalent ratio of hydroxyl groups in the polyhydroxy compound (C) to isocyanate groups in the polyisocyanate compound (D) is preferably 0.9 to 1.1.
However, among the polyhydroxy compounds (C), urethane skeletons produced from polyhydroxy compounds having a molecular weight of 100 or less have strong bonds between urethane skeletons, making it difficult to incorporate cyanamide. Therefore, among the polyhydroxy compounds (C), the equivalent ratio of hydroxyl groups in the polyhydroxy compounds having a number average molecular weight of 100 or less to isocyanate groups in the polyisocyanate compounds (D) is preferably 0.85 or less. It is preferably 0.75 or less.

A curing aid can be added to the epoxy resin composition of the present invention as long as it does not lose its functionality. Examples of curing aids include imidazole-based curing aids and urea-based curing aids, but are not limited to these.

Examples of imidazole-based curing aids include 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, Imidazole compounds such as 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl 6-4',5'-dihydroxymethylimidazole and 1-cyanoethyl-2-ethyl-4methylimidazole can be used. . Furthermore, examples of imidazole compounds containing a triazine ring include 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[ 2′-Undecylimidazolyl-(1′)]-ethyl-s-triazine and the like, but are not limited to these.

Additives such as core-shell rubber can be added to the epoxy resin composition of the present invention within a range that does not impair its functionality.

As the core-shell rubber, a part of the surface of the particulate core component is obtained by graft-polymerizing a shell component polymer different from the core component on the surface of the particulate core component whose main component is a crosslinked rubber-like polymer or elastomer. Alternatively, the whole is covered with a shell component. For example, as the core-shell polymer-dispersed epoxy masterbatch, "Kaneace" commercially available from Kaneka can be suitably used.

The amount of the core-shell rubber compounded is preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, per 100 parts by mass of the epoxy resin composition. If the blending amount is 0.5 parts by mass or more, the fracture toughness required for the fiber-reinforced composite material after molding can be easily obtained. Since the viscosity of the epoxy resin composition for the material can be suppressed from increasing and the reinforcing fibers can be impregnated with it without difficulty, it is more suitable for fiber-reinforced composite materials.

The epoxy resin composition of the present invention may further contain other stabilizers, modifiers and the like. A preferable stabilizer is a boric acid compound represented by B(OR) ₃ (wherein R represents a hydrogen atom, an alkyl group or an aryl group). The amount of the boric acid compound compounded is 0.01 to 10 parts by mass, preferably 0.1 to 3 parts by mass, per 100 parts by mass of the entire resin composition. If the addition amount is less than 0.01 part by mass, the stability during storage cannot be ensured. do not have.

An antifoaming agent and a leveling agent can be added to the epoxy resin composition of the present invention as additives for the purpose of improving surface smoothness. These additives can be blended in an amount of 0.01 to 3 parts by mass, preferably 0.01 to 1 part by mass, per 100 parts by mass of the entire resin composition. When the amount is less than 0.01 part by mass, the effect of smoothing the surface is not exhibited, and when the amount exceeds 3 parts by mass, the additive bleeds out on the surface, which adversely impairs the smoothness, which is not preferable. .

The epoxy resin composition of the present invention is produced by uniformly mixing the above components (A) and (B). The resulting epoxy resin composition has good impregnating properties into the reinforcing fibers, and the resin is less likely to drip from the fibers even after impregnation. Furthermore, the epoxy resin composition of the present invention is stable at a room temperature of 25° C. and hardly changes in viscosity, and it takes 72 hours or more until the viscosity doubles under the conditions of a temperature of 40° C. and an air atmosphere or an inert gas atmosphere. , and not only can ensure stable impregnation of reinforcing fibers during the production of prepregs having a long impregnation process, but it does not thicken during storage, so hardening caused by poor resin flowability. A fiber-reinforced composite material with few voids and excellent surface smoothness can be obtained.

The epoxy resin composition of the present invention can also contain other curable resins. Examples of such curable resins include unsaturated polyester resins, curable acrylic resins, curable amino resins, curable melamine resins, curable urea resins, curable cyanate ester resins, curable urethane resins, curable oxetane resins, Examples include, but are not limited to, curable epoxy/oxetane composite resins.

The epoxy resin composition of the present invention preferably has a viscosity of 5 to 80 Pa·s/25°C, more preferably 6 to 50 Pa·s/25°C, particularly preferably 7 to 30 Pa, as measured using an E-type viscometer. - It is preferable that it is s/25 degreeC. If the viscosity is too high, the ability to impregnate carbon fibers deteriorates, and if the viscosity is too low, sedimentation of the imidazole-based curing aid and the like is caused.
In addition, the epoxy resin composition of the present invention does not need to contain a solvent, and is excellent in storage stability as a one-liquid composition.

Manufacture of the epoxy resin composition of this invention can be manufactured by various well-known methods. For example, there is a method of kneading each component with a disper, a planetary mixer, or a kneader. Moreover, you may knead using a twin-screw extruder. When solid components are present in the epoxy resin composition, they are dispersed in each component in a solid state. However, when all the components are kneaded at once, they may aggregate and become poorly dispersed. An epoxy resin composition with poor dispersion is not preferable because it causes unevenness in physical properties in the cured product and poor curing. Therefore, it is preferable to use a part of the solid component and the epoxy resin, perform preliminary kneading with a triple roll, and use it as a masterbatch.

The epoxy resin composition of the present invention is suitably used for fiber-reinforced composite materials, particularly prepregs in which fibers are pre-impregnated with the composition, especially tow prepregs.
The method for producing a prepreg or tow prepreg using the epoxy resin composition of the present invention is not particularly limited. A method in which the organic solvent is evaporated by using an oven or the like after impregnation while heating to form a tow prepreg. 2) Forming a film of the epoxy resin composition which has been heated and reduced in viscosity without using an organic solvent on a roll or release paper, transferring the film onto one or both sides of the reinforcing fiber bundle, and then passing it through a bending roll or a pressure roll. A method of pressurizing and impregnating with. 3) The viscosity of the epoxy resin composition is reduced by heating, and a method of impregnating the reinforcing fiber bundle while immersing it may be used. Above all, the method described in 3) can be preferably used because substantially no organic solvent remains in the tow prepreg and high-quality tow prepreg can be produced with high productivity. A resin-impregnated tow prepreg can be obtained by using such a manufacturing method.

The reinforcing fiber used in the epoxy resin composition of the present invention is selected from glass fiber, aramid fiber, carbon fiber, boron fiber, etc. Carbon fiber is used to obtain a fiber-reinforced composite material having excellent strength. is preferred.

In the molded article composed of the epoxy resin composition of the present invention and reinforcing fibers, the volume content of the reinforcing fibers is preferably 30 to 75%, more preferably 45 to 75%. Since a molded article having a small amount of reinforcing fibers and a high volume content of reinforcing fibers can be obtained, a molding material having excellent strength can be obtained.

The epoxy resin composition of the present invention can be heated at an arbitrary temperature in the range of 80 to 180° C. for an arbitrary time in the range of 0.5 to 10 hours to proceed with the cross-linking reaction and obtain a cured product. The heating condition may be one step, or may be a multi-step condition combining a plurality of heating conditions. In particular, assuming a high-pressure container filled with hydrogen gas such as that used in fuel cells, it is heated at an arbitrary temperature in the range of 80 to 150 ° C. for an arbitrary time in the range of 0.5 to 5 hours. By curing, desired physical properties of the cured product can be obtained.

EXAMPLES Next, the present invention will be specifically described based on examples. The present invention is not limited to this specific example, and various modifications and changes are possible without departing from the gist of the present invention.

In order to obtain the resin composition of each example, the following resin raw materials were used.
・ Liquid bisphenol F type epoxy resin: YDF-170 (manufactured by Nippon Steel & Sumikin Chemical)
Hydroxyl equivalent 2489 (g/eq), epoxy equivalent 168 (g/eq)
・ Liquid bisphenol A type epoxy resin: YD-128 (manufactured by Nippon Steel & Sumikin Chemical)
Hydroxyl equivalent 1800 (g/eq), epoxy equivalent 188 (g/eq)
・ Liquid bisphenol A type epoxy resin: YD-8125 (manufactured by Nippon Steel & Sumikin Chemical)
Hydroxyl equivalent 8000 (g/eq), epoxy equivalent 172 (g/eq)
・Cyanamide: manufactured by Kanto Chemical Co., Ltd. ・Polypropylene glycol: P-2000 (made by ADEKA)
Hydroxyl equivalent 1020 (g/eq)
・ 1,4-Butanediol (1,4-BD): manufactured by Kanto Chemical, hydroxyl equivalent 45 (g / eq)
・Diisocyanate: Cosmonate PH (manufactured by Mitsui Chemicals)
・Di-n-butyltin dilaurate: manufactured by Kishida Chemical

The measurement method is shown below.
Epoxy equivalent: Measured according to JIS K 7236 standard. Specifically, a potentiometric titrator was used, tetrahydrofuran was used as a solvent, a tetraethylammonium bromide acetic acid solution was added, and a 0.1 mol/L perchloric acid-acetic acid solution was used.
Viscosity: According to JIS K7117-1. Specifically, the viscosity of the uncured resin composition at 25° C. was measured with an E-type viscometer.
Thickening rate (25°C): Measured according to JIS K7177-1 after standing in a constant temperature and humidity chamber at 25°C.
Thickening rate (40°C): Measured according to JIS K7177-1 after standing in a hot air circulating oven at 40°C.
Hydroxyl equivalent: 25 ml of dimethylformamide is placed in a 200 ml conical flask with a glass stopper, and a sample containing no more than 11 mg/equivalent of hydroxyl is accurately weighed and dissolved. Add 20 ml of the 1 mol/L-phenylisocyanate toluene solution and 1 ml of the dibutyltinmalate catalyst solution with a pipette, shake well to mix, seal tightly, and react for 30 to 60 minutes. After completion of the reaction, 20 ml of a 2 mol/L-dibutylamine toluene solution is added, mixed well by shaking, and allowed to stand for 15 minutes to react with excess phenyl isocyanate. Next, 30 ml of methyl cellosolve and 0.5 ml of bromcresol green indicator are added, and excess amine is titrated with a standardized 1 mol/L-trimethyl perchloride cellosolve solution. Since the indicator changes from blue to green to yellow, the point at which it first turned yellow was taken as the end point, and the hydroxyl group equivalent was determined using the following formulas i and ii.
Hydroxyl equivalent (g/eq) = (1000 x W)/C(SB) (i)
C: 1 mol/l - concentration of methyl perchlorate cellosolve solution mol/l
W: Sample amount (g)
S: Titration volume (ml) of 1 mol/l-methyl perchlorate cellosolve solution required for sample titration
B: Titration volume of 1mol/l-methyl perchlorate cellosolve solution required for blank test during titration
(ml)
C=(1000×W)/{121×(sb)} (ii)
w: Amount of tris-(hydroxymethyl)-aminomethane sampled for standardization (g)
s: Titration volume (ml) of 1 mol/l-methyl perchlorate cellosolve solution required for titration of tris-(hydroxymethyl)-aminomethane
b: Titration volume of 1 mol/l-methyl perchlorate cellosolve solution required for blank test during standardization
(ml)

Synthesis example 1
89.2 g of "Epotato YD-128" as an epoxy resin was placed in a 1 L four-necked separable flask equipped with a nitrogen inlet tube, a stirrer and a temperature controller, and mixed with stirring at room temperature for 15 minutes. Next, 8.3 g of "Cosmonate PH" and 0.03 g of di-n-butyltin dilaurate as polyisocyanate were charged into the same separable flask and reacted at 120° C. for 2 hours, followed by "1,4-butanediol ] was charged into the same separable flask and reacted at 120° C. for 2 hours to obtain 100 g of a urethane-modified epoxy resin. Completion of the reaction was confirmed by the disappearance of the absorption spectrum of the isocyanate group by IR measurement. The epoxy equivalent of the obtained urethane-modified epoxy resin (A1) was 209 g/eq.

Synthesis example 2
89.1 g of "Epotato YDF-170" as an epoxy resin and 2.2 g of "P-2000" as a polyol were charged into a 1 L four-necked separable flask equipped with a nitrogen inlet tube, a stirrer, and a temperature controller. The mixture was stirred for 1 minute. Next, 7.7 g of "Cosmonate PH" and 0.03 g of di-n-butyltin dilaurate as polyisocyanate were charged into the same separable flask and reacted at 120° C. for 2 hours, followed by "1,4-butanediol ] was charged into the same separable flask and reacted at 120° C. for 2 hours to obtain 100 g of a urethane-modified epoxy resin. Completion of the reaction was confirmed by the disappearance of the absorption spectrum of the isocyanate group by IR measurement. The epoxy equivalent of the obtained urethane-modified epoxy resin (A2) was 189 g/eq.

Synthesis example 3
Synthesis was carried out according to the synthesis method of Synthesis Example 2 and the composition of Table 1 to obtain 100 g of a urethane-modified epoxy resin. Completion of the reaction was confirmed by the disappearance of the absorption spectrum of the isocyanate group by IR measurement. The epoxy equivalent of the obtained urethane-modified epoxy resin (A3) was 189 g/eq.

Synthesis example 4
Synthesis was carried out according to the synthesis method of Synthesis Example 2 and the composition of Table 1 to obtain 100 g of a urethane-modified epoxy resin. Completion of the reaction was confirmed by the disappearance of the absorption spectrum of the isocyanate group by IR measurement. The epoxy equivalent of the obtained urethane-modified epoxy resin (A3) was 189 g/eq.

Synthesis example 5
Synthesis was carried out according to the synthesis method of Synthesis Example 2 and the composition of Table 1 to obtain 100 g of a urethane-modified epoxy resin. Completion of the reaction was confirmed by the disappearance of the absorption spectrum of the isocyanate group by IR measurement. The epoxy equivalent of the obtained urethane-modified epoxy resin (A5) was 189 g/eq.

Synthesis example 6
Synthesis was carried out according to the synthesis method of Synthesis Example 2 and the composition of Table 1 to obtain 100 g of a urethane-modified epoxy resin. Completion of the reaction was confirmed by the disappearance of the absorption spectrum of the isocyanate group by IR measurement. The epoxy equivalent of the obtained urethane-modified epoxy resin (A6) was 209 g/eq.

Synthesis example 7
Synthesis was carried out according to the synthesis method of Synthesis Example 2 and the composition of Table 1 to obtain 100 g of a urethane-modified epoxy resin. Completion of the reaction was confirmed by the disappearance of the absorption spectrum of the isocyanate group by IR measurement. The epoxy equivalent of the obtained urethane-modified epoxy resin (A6) was 189 g/eq.

Synthesis example 8
Synthesis was carried out according to the synthesis method of Synthesis Example 2 and the composition of Table 1 to obtain 100 g of a urethane-modified epoxy resin. Completion of the reaction was confirmed by the disappearance of the absorption spectrum of the isocyanate group by IR measurement. The epoxy equivalent of the obtained urethane-modified epoxy resin (A6) was 248 g/eq.

Examples 1 to 8 and Comparative Examples 1 and 2
Urethane-modified epoxy resin (A), cyanamide (B) and epoxy resin were added according to the composition shown in Table 2, and kneaded for 6 minutes at 2000 rpm and 4.0 kPa using a THINKY PLANETARY VACUUM MIXER (manufactured by THINKY CORPORATION). An epoxy resin composition was prepared. Table 2 also shows the physical properties of the epoxy resin composition.

Claims (7)

An epoxy resin composition containing a urethane-modified epoxy resin (A) and a cyanamide (B) as essential components and used as a matrix resin for reinforcing fibers , wherein the urethane-modified epoxy resin (A) comprises an epoxy resin and a polyhydroxy compound (C ) and polyisocyanate compound (D) as raw materials, and the total amount of polyhydroxy compound (C) and polyisocyanate compound (D) is 5 to 30% by weight with respect to the total amount of urethane-modified epoxy resin (A). There, the amount of cyanamide (B) is 20 to 90% by weight with respect to the total amount of the structure derived from the polyhydroxy compound (C) and the polyisocyanate compound (D), and the urethane-modified epoxy resin (A) An epoxy resin composition for fiber-reinforced composite materials , characterized in that cyanamide (B) is incorporated in hydrogen bonds between urethane skeletons.
However, it does not contain a fibrous inorganic filler with an aspect ratio of 3-500. The epoxy resin composition according to claim 1, which has a viscosity of 5 to 80 Pa·s at 25°C measured using an E-type viscometer. A method for producing an epoxy resin composition containing a urethane-modified epoxy resin (A) and a cyanamide (B) and used as a matrix resin for reinforcing fibers, comprising an epoxy resin (A1) having a secondary hydroxyl group and a polyhydroxy compound Using (C) and the polyisocyanate compound (D), reacting raw materials in which the total amount of the polyhydroxy compound (C) and the polyisocyanate compound (D) is 5 to 30% by weight to produce a urethane-modified epoxy resin (A). After obtaining, cyanamide (B) is blended in an amount of 20 to 90% by weight based on the total amount of the polyhydroxy compound (C) and the polyisocyanate compound (D) used as the raw materials to obtain the urethane-modified epoxy resin (A). A method for producing an epoxy resin composition for fiber-reinforced composite materials , characterized in that cyanamide (B) is incorporated in hydrogen bonds between urethane skeletons.
However, it does not contain a fibrous inorganic filler with an aspect ratio of 3-500. The fiber according to claim 3, wherein the equivalent ratio of hydroxyl groups in the polyhydroxy compounds (C) having a number average molecular weight of 100 or less to isocyanate groups in the polyisocyanate compounds (D) is 0.85 or less. A method for producing an epoxy resin composition for reinforced composites . A fiber-reinforced composite material comprising the epoxy resin composition for a fiber-reinforced composite material according to claim 1 or 2 and a reinforcing fiber blended therein. The fiber-reinforced composite material according to claim 5, wherein the volume content of the reinforcing fibers is 30-75%. A molded article obtained by curing the fiber-reinforced composite material according to claim 5 or 6.