TW202214739A - Precursor mixture of in situ polymerization type thermoplastic epoxy resin, epoxy resin composition, epoxy resin composition sheet, prepreg, and in situ polymerization type thermoplastic fiber-reinforced plastic using same - Google Patents

Abstract

The present invention relates to an in situ polymerization type thermoplastic epoxy resin, and provides an in situ polymerization type thermoplastic epoxy resin or thermoplastic fiber-reinforced plastic, which has excellent heat resistance, while being suppressed in the formation of a gel fraction. A precursor mixture which is obtained by addition polymerization of an epoxy resin and a bifunctional phenolic compound, and which is used for an in situ polymerization type thermoplastic epoxy resin. This precursor mixture is characterized in that: an epoxy resin that contains 50% by weight or more of a bifunctional epoxy resin (a) represented by formula (1), and a bifunctional phenolic compound are contained as essential components; from 0.9 to 1.1 moles of the bifunctional phenolic compound is contained relative to 1 mole of the epoxy resin; and the viscosity at 60 DEG C is from 1 Pa·s to 50 Pa·s. In formula (1), A is represented by formula (2); n is the number of repeating units, and the average value thereof is within the range of from 0 to 5; and X represents a single bond, an alkylene group having from 1 to 9 carbon atoms, -O-, -CO-, -COO-, -S- or -SO2-; each Y1 independently represents an alkyl group having from 1 to 4 carbon atoms or an aryl group having from 6 to 10 carbon atoms; each of Y2 and Y3 independently represents a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, or an aryl group having from 6 to 10 carbon atoms.

Description

Precursor mixture of in-situ polymerized thermoplastic epoxy resin, epoxy resin composition, epoxy resin composition sheet, prepreg, and in-situ polymerized thermoplastic fiber reinforced plastic using the same

The present invention relates to an in-situ polymerized thermoplastic epoxy resin and thermoplastic fiber reinforced plastic. Here, the so-called in-situ polymerized thermoplastic resin refers to a low molecular weight at the time of shipment from the factory, and on the other hand, after being impregnated into reinforcing fibers at the manufacturing site of fiber reinforced thermoplastics (FRTP), it is Thermal melting (heating and melting) is a resin that rapidly polymerizes and can be converted into a high molecular weight thermoplastic resin.

Thermoplastic resin is a material that can be easily molded by being plasticized by heating. However, thermoplastic resins generally have a high molecular weight and have a high melt viscosity, so high temperature and high pressure are required for molding. It is not easy to become a small space or compound with materials that are difficult to heat or pressurize.

In view of this problem, Patent Document 1 proposes a method for producing an in-situ polymerization-type thermoplastic epoxy resin using a bifunctional epoxy resin and a bifunctional hardener. Both difunctional epoxy resins and difunctional hardeners are monomers or oligomers, and have low viscosity compared to common thermoplastic resins. In addition, since it can be dissolved even with a low-boiling organic solvent, it can be reliably impregnated and can be easily dried. By in-situ polymerization, thermoplastic resins with porosity reduced to a sufficient level can be obtained.

In addition, Non-Patent Document 1 discloses that, with regard to an in-situ polymerization type thermoplastic epoxy resin, the glass transition temperature (Tg) of the polymer is controlled by changing the skeleton of the main chain according to the type of epoxy resin or phenol compound. . However, here, further studies have not been conducted on materials that change the skeleton of the main chain. According to the study by the present inventors, if the polymerization is sufficiently carried out in order to express mechanical strength by using a skeleton having excellent heat resistance, it will gel and fail to express thermoplasticity, so that it is impossible to take both of these cases into consideration.

Patent Document 2 describes the use of a specific catalyst as a method for obtaining a high-molecular-weight epoxy resin excellent in storage stability. The high-molecular-weight epoxy resin obtained by polymerizing while stirring was revealed using an isophorone diisocyanate adduct as a curing agent, but the characteristics of the high-molecular-weight epoxy resin itself are not described other than the epoxy equivalent. be recorded.

In addition, Patent Document 3 discloses a method of producing a crystalline adduct of both of which the melting point is lowered by heating and cooling a mixture of bisphenol A and bisphenol TMC. Only the melting point of the bisphenol crystalline adduct is disclosed, and there is no description about the application to epoxy resins, especially in-situ polymerization thermoplastic epoxy resins. [Prior Art Literature] [Patent Literature]

[Patent Document 1] International Publication WO2004/060981 [Patent Document 2] Japanese Patent Laid-Open No. 2015-157907 [Patent Document 3] Japanese Patent Laid-Open No. 9-059196 [Non-patent literature]

[Non-Patent Document 1] "General Discussion on Epoxy Resins (Recent Progress I)", p422-p430 (Epoxy Resin Technology Association)

In the present invention, with regard to an in-situ polymerization-type thermoplastic epoxy resin, an object of the present invention is to provide an in-situ polymerization-type thermoplastic epoxy resin or thermoplastic fiber-reinforced plastic which is excellent in heat resistance and has less generation of gel components, and which can be obtained The epoxy resin composition and its precursor mixture. [Means of Solving Problems]

Efforts were made to solve the above-mentioned problems, and as a result, it was found that when a substituent such as an alkyl group is used in the ortho-position with respect to the glycidyloxy group (glycidyloxy group) of the epoxy resin used, the The polymer has excellent heat resistance, does not gel, and can obtain a high molecular weight epoxy resin with an increased molecular weight and thermoplasticity. The polymerization reaction proceeds in the same manner when the carbon fiber is impregnated, so that it can be provided as a thermoplastic fiber-reinforced plastic.

此處，式（1）中的A為式（2），n為重複數且其平均值為0～5。X為單鍵、碳數1～9的伸烷基、-O-、-CO-、-COO-、-S-、-SO ₂-的任一者，Y ¹獨立地為碳數1～4的烷基、碳數6～10的芳基的任一者，Y ²及Y ³分別獨立地為氫原子、碳數1～4的烷基、碳數6～10的芳基的任一者。 That is, the present invention is a precursor mixture for use in an in-situ polymerized thermoplastic epoxy resin obtained by addition polymerization of an epoxy resin (A) and a difunctional phenolic compound (B) , which is characterized in that: an epoxy resin (A) containing 50% by weight or more of a bifunctional epoxy resin (a) represented by the following formula (1), and a bifunctional phenol compound (B) as essential components, relative to In the epoxy resin (A) 1 mol, the bifunctional phenol compound (B) is 0.9 mol to 1.1 mol, and the viscosity at 60° C. is 1 Pa·s or more and 50 Pa·s or less. [hua 1]

Here, A in the formula (1) is the formula (2), n is the number of repetitions, and the average value thereof is 0-5. X is a single bond, an alkylene group having 1 to 9 carbon atoms, any one of -O-, -CO-, -COO-, -S-, and -SO ₂ -, and Y ¹ is independently a carbon number of 1 to 4 Any one of the alkyl group and the aryl group having 6 to 10 carbon atoms, Y ² and Y ³ are each independently any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 10 carbon atoms. .

When the precursor mixture is made into a thickness of 2 mm, the haze value in the thickness direction is preferably less than 30%, and the weight average molecular weight of the precursor mixture obtained by the standard polystyrene calibration curve is preferably more than 300 and below 500.

The bifunctional phenol compound (B) is preferably a bisphenol compound and/or a biphenol compound, and the ratio of the largest component in the bifunctional phenol compound (B) is preferably 90% by weight or less.

In addition, the present invention is an epoxy resin composition prepared by mixing a polymerization catalyst with the precursor mixture and making them compatible with each other.

The epoxy resin composition preferably has a haze value in the thickness direction of less than 30% when the epoxy resin composition has a thickness of 2 mm, and preferably has a viscosity of 3 Pa·s or more and 150 Pa·s or less at 60°C.

Moreover, this invention is an epoxy resin composition sheet which made the said epoxy resin composition into thickness 10 micrometers or more and 300 micrometers or less.

In addition, the present invention is an in-situ polymerization type thermoplastic epoxy resin obtained by polymerizing the epoxy resin composition; or a sheet-like in-situ polymerization type thermoplastic epoxy resin, which is obtained by polymerizing the epoxy resin composition. Oxygen resin composition sheet is polymerized. These in-situ polymerization-type thermoplastic epoxy resins and sheet-like in-situ polymerization-type thermoplastic epoxy resins preferably have a gel fraction of 0% by weight or more and 10% by weight or less.

In addition, the present invention is a prepreg, which is a prepreg obtained from the epoxy resin composition and/or the epoxy resin composition sheet, and reinforcing fibers, and is an in-situ polymerization type A thermoplastic fiber-reinforced plastic obtained by polymerizing the prepreg.

The precursor mixture for the in-situ polymerization type thermoplastic epoxy resin of the present invention does not precipitate crystals, and an epoxy resin composition or prepreg excellent in handleability can be obtained in a hot melt method. Moreover, although the glass transition temperature of the polymer which has a sufficiently high molecular weight is raised, the in-situ polymerization type thermoplastic epoxy resin which can reduce the generation|occurence|production of a gel can be obtained.

Hereinafter, the present invention will be described in detail based on its preferred embodiments. The in-situ polymerization-type thermoplastic epoxy resin is obtained by addition polymerization of an epoxy resin (A) and a difunctional phenolic compound (B), and is used as a precursor in the in-situ polymerization-type thermoplastic epoxy resin of the present invention The mixture (sometimes referred to as a precursor) contains 50% by weight or more of the bifunctional epoxy resin (a) represented by the formula (1) as the epoxy resin (A) as an essential component. Preferably it is 66 weight% or more, More preferably, it is 75 weight% or more, More preferably, it is 80 weight% or more. Moreover, it is preferable that the epoxy equivalent of an epoxy resin (A) is 150 g/eq - 350 g/eq.

In formula (1), A is formula (2). n is the number of repetitions, and the average value thereof is 0-5, preferably 0-1.

In the formula (2), X is a single bond, an alkylene group having 1 to 9 carbon atoms, any one of -O-, -CO-, -COO-, -S-, and -SO ₂ -. Examples of the alkylene group having 1 to 9 carbon atoms include -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -CHPh-, -C(CH ₃ )Ph-, 1,1-cyclopropylidene, 1,1-cyclobutylene, 1,1-cyclopentylene, 1,1-cyclohexylene, 4-methyl-1 ,1-cyclohexylene, 3,3,5-trimethyl-1,1-cyclohexylene, 1,1-cyclooctylene, 1,1-cyclononyl, 1,2-ethylidene , 1,2-cyclopropylidene, 1,2-cyclobutylene, 1,2-cyclopentylene, 1,2-cyclohexylene, 1,2-phenylene, 1,3-propylene base, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclohexylene, 1,3-phenylene, 1,4-butylene, 1,4-cycloextended Hexyl, 1,4-phenylene, etc. In addition, Ph represents a phenyl group. Among these, single bond, -O-, -CO-, -COO-, -S-, -SO ₂ -, -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) are preferred ₂ -, -CHPh-, -C(CH ₃ )Ph-, 1,1-cyclohexylene, 4-methyl-1,1-cyclohexylene, 3,3,5-trimethyl-1,1 -cyclohexylene, 1,4-cyclohexylene, 1,4-phenylene, more preferably single bond, -O-, -CO-, -COO-, -S-, -SO ₂ -, -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CH ₃ )Ph-, 1,1-cyclohexylene, 3,3,5-trimethyl-1,1 - cyclohexylene. In addition, Ph represents a phenyl group.

Y ¹ in formula (2) is independently any of an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 10 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl. Examples of the aryl group having 6 to 10 carbon atoms include phenyl, tolyl, ethylphenyl, xylyl, n-propylphenyl, isopropylphenyl, mesityl, and naphthyl. Among these, methyl, ethyl, n-propyl, n-butyl, tert-butyl, phenyl, tolyl, xylyl, and naphthyl are preferred, and methyl, ethyl, and n-propyl are more preferred. base, n-butyl, tert-butyl, phenyl, tolyl. Y ² in formula (2) is independently any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 10 carbon atoms, and is preferably a substituent other than a hydrogen atom. The substituents are the same as those exemplified for Y ¹ above. Preferably, Y ² and Y ¹ are the same. Y ³ in formula (2) is independently any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 10 carbon atoms. The substituents are the same as those exemplified in ^Y1 . Preferably, Y ³ is the same as a hydrogen atom or Y ¹ .

As the bifunctional epoxy resin (a), for example, a tetramethylbisphenol F-type epoxy resin (for example, YSLV-80XY (manufactured by NIPPON STEEL Chemical & Material Co., Ltd.), etc., can be mentioned) , tetramethyl biphenol type epoxy resin (for example, YX-4000 (Mitsubishi Chemical Co., Ltd.), etc.), biscresol fluorene type epoxy resin (for example, OGSOL CG-500 (Osaka Gas Chemical Co., Ltd.) (manufactured by Osaka Gas Chemical Co., Ltd.) etc.).

Moreover, about the epoxy resin other than a bifunctional epoxy resin (a), if it is a bifunctional epoxy resin, you may use together, and it is preferable that the purity is 95% or more. Moreover, if the purity as a bifunctional compound is high, a positional isomer or an oligomer may be included. Examples of epoxy resins that can be used together include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, bisphenol acetophenone epoxy resin, diphenyl sulfide Ether type epoxy resin, diphenyl ether type epoxy resin, bisphenol fluorene type epoxy resin and other bisphenol type epoxy resin, or biphenol type epoxy resin, diphenyl dicyclopentadiene type epoxy resin , alkanediol type epoxy resin, dihydroxynaphthalene type epoxy resin, dihydroxybenzene type epoxy resin, etc., but not limited to these.

When a monofunctional impurity is contained, since the molecular weight after polymerization does not increase, there is a possibility that the mechanical properties of the produced thermoplastic resin may be deteriorated. Therefore, the amount of monofunctional impurities is preferably 2% by weight or less with respect to the bifunctional epoxy resin. When an impurity of trifunctional or more is contained, since it is easy to form a cross-linked structure from the impurity as a starting point, in addition to the possibility that the dispersion of the polymer may be increased, there is a possibility that the thermoplasticity may be deteriorated by gelation. Therefore, it is preferable that it is 1 weight% or less with respect to a bifunctional epoxy resin with respect to the impurity of trifunctional or more. Furthermore, regarding the impurity component which does not have an active group that reacts with either epoxy resin or phenolic hydroxyl group, and does not inhibit the polymerization reaction when it is a simple substance, if the amount increases, the molecular weight after polymerization may also decrease. . Therefore, it is preferable that it is 2 weight% or less with respect to a bifunctional epoxy resin.

Moreover, the bifunctional phenol compound (B) which is another essential component is a compound which has two phenolic hydroxyl groups in one molecule, and it is preferable that the purity is 95 weight% or more. Moreover, if the purity as a bifunctional compound is high, a positional isomer may be included. That is, impurities and impurity components are preferably as follows. When a monofunctional impurity is contained, since the molecular weight after polymerization does not increase, there is a possibility that the mechanical properties of the produced thermoplastic resin may be deteriorated. Therefore, the amount of monofunctional impurities is preferably 2% by weight or less with respect to the bifunctional phenol compound. When an impurity of trifunctional or more is contained, since it is easy to form a cross-linked structure from the impurity as a starting point, in addition to the possibility that the dispersion of the polymer may be increased, there is a possibility that the thermoplasticity may be deteriorated by gelation. Therefore, it is preferable that it is 1 weight% or less with respect to a bifunctional phenol compound with respect to a trifunctional or more impurity. Furthermore, regarding the impurity component which does not have an active group that reacts with either epoxy resin or phenolic hydroxyl group, and does not inhibit the polymerization reaction when it is a simple substance, if the amount increases, the molecular weight after polymerization may also decrease. . Therefore, it is preferable that this impurity component is 2 weight% or less with respect to a bifunctional phenol compound.

The bifunctional phenol compound (B) is exemplified below, but it is not limited to the following as long as it is bifunctional. There are bisphenol A, bisphenol F (above, manufactured by NIPPON STEEL Chemical & Material Co., Ltd.), bisphenol fluorene, biscresol fluorene (above, Osaka Gas Chemical Co., Ltd. company), Bis-E, Bis-Z, BisOC-FL, BisP-AP, BisP-CDE, BisP-HTG, BisP-MIBK, BisP-3MZ, S-BOC, Bis25X-F (above, Honshu Chemical Industry Co., Ltd. Co., Ltd.), bisphenol S and other bisphenols, or hydroquinone, methylhydroquinone, dibutylhydroquinone, resorcinol, methylresorcinol, catechol , phenols such as methyl catechol, or naphthalene diphenols such as naphthalenediol, or biphenols such as biphenol, dimethyl biphenol, and tetramethyl biphenol. Among these, bisphenol compounds or biphenol compounds are preferred.

Two or more types of bifunctional phenolic compounds (B) can be used. When a plurality of difunctional phenol compounds are used, the ratio of the largest component is preferably 90% by weight or less, more preferably 80% by weight or less. In addition, the melting point of the bifunctional phenol compound (B) is preferably 150° C. or higher.

In the precursor mixture, the organic solvent is not an essential component. It is preferably 10 parts by weight or less with respect to 100 parts by weight of the total amount of the epoxy resin (A) and the bifunctional phenol compound (B). More preferably, it is 5 parts by weight or less, and desirably not contained. Moreover, when using an organic solvent, it is preferable that the boiling point of an organic solvent in 1 atmospheric pressure is 200 degrees C or less.

The melting conditions of the precursor mixture depend on the melting point of the bifunctional phenol compound (B) to be used, and are preferably melted at 200° C. or lower. Alternatively, the bifunctional phenol compound (B) may be melted in advance at 300° C. or lower, preferably 200° C. or lower, and then the epoxy resin (A) may be added, rapidly cooled, and mixed at 150° C. or lower.

Here, the mixing ratio of the epoxy resin (A) and the bifunctional phenol compound (B) is 0.9 mol to 1.1 mol of the bifunctional phenol compound (B) with respect to 1 mol of the epoxy resin (A), It is preferably 0.95 mol to 1.05 mol, more preferably 0.96 mol to 1.04 mol, still more preferably 0.97 mol to 1.03 mol. When the compounding ratio of the bifunctional phenol compound (B) is within this range, the molecular weight of the in-situ polymerization-type thermoplastic epoxy resin obtained is sufficiently extended, which is preferable.

The molten mixture is desirably completely melted. For example, the molten mixture is placed in a glass petri dish so as to have a thickness of 2 mm without bubbles, and the haze value in the thickness direction is measured. In this case, When the haze value in the thickness direction is less than 30%, it is judged that it is melted to a level that does not affect the polymerization reaction. About the haze value, it is more preferable that it is less than 20%, and it is still more preferable that it is less than 10%.

In addition, the viscosity of the precursor mixture at 60° C. is 1 Pa·s or more and 50 Pa·s or less. When the viscosity is less than 1 Pa·s, the precursor mixture of the thermoplastic epoxy resin and its subsequent materials become too soft, and thus the handleability around room temperature may be deteriorated. In addition, when the viscosity exceeds 50 Pa·s, the workability at the time of preparing the polymerization catalyst in the next step may be deteriorated, or the storage stability may be deteriorated due to the need for treatment at high temperature. A more preferable viscosity is 3 Pa·s or more and 40 Pa·s or less, and preferably 5 Pa·s or more and 30 Pa·s or less.

In addition, the weight average molecular weight of the precursor mixture obtained from a standard polystyrene calibration curve is preferably 300 or more and 500 or less. The more preferable weight average molecular weight is 300 or more and 450 or less, and 300 or more and 400 or less are desirable. By setting the weight average molecular weight within the range, the viscosity of the precursor mixture at 60° C. can easily be set within a preferable range.

The epoxy resin composition of the present invention is obtained by mixing the precursor mixture and the polymerization catalyst. As the polymerization catalyst that can be used, for example, phosphine-based compounds, quaternary phosphonium salts, imidazoles, tertiary amines, and the like can be mentioned. Among them, phosphine-based compounds are particularly preferred, and triphenylphosphine, tris(o-tolyl)phosphine, tris(p-tolyl)phosphine, tris(p-methoxyphenyl)phosphine, tris(2,6) phosphine are particularly preferred -Dimethoxyphenyl)phosphine (both are manufactured by Beixing Chemical Industry Co., Ltd.). In addition, among the quaternary phosphonium salts, HISHICOLIN PX-4MP and HISHICOLIN PX-4ET (both manufactured by Nippon Chemical Industries, Ltd.) are preferable. Furthermore, among the imidazoles, 2-phenylimidazole and 2,3-dihydro-1H-pyrrolo-[1,2-a]benzimidazole (all manufactured by Shikoku Chemical Industry Co., Ltd.) are preferred. The compounding quantity of a polymerization catalyst is 0.05 weight% or more and 10 weight% or less with respect to the sum of an epoxy resin (A) and a phenolic compound (B). More preferably, it is 0.1% by weight or more and 5% by weight or less. When the amount of the catalyst is less than 0.05% by weight, the molecular weight is not sufficiently increased, or the polymerization takes time, and productivity is impaired. On the other hand, when it is used in excess of 10% by weight, not only storage stability is impaired, but also a problem in that the molecular weight is not sufficiently increased occurs.

The epoxy resin composition of the present invention is a mixture containing an epoxy resin, a phenol compound, and a polymerization catalyst, and can be polymerized by heating. When adding the polymerization catalyst, a small amount of an organic solvent may be used for the purpose of uniform mixing. The usage-amount of an organic solvent is 10 weight% or less of the sum of an epoxy resin and a phenolic compound, Preferably it is 5 weight% or less, More preferably, it is 1 weight% or less. When the organic solvent is used in an amount exceeding 10% by weight, there is a problem that the molecular weight of the polymer is not sufficiently raised.

Moreover, it is preferable that the viscosity at 60 degreeC of an epoxy resin composition is 3 Pa.s or more and 150 Pa.s or less. When the viscosity is less than 3 Pa·s, the resin component in the resin sheet or the prepreg to be described later becomes too soft, and thus the handleability around room temperature may be deteriorated. In addition, when the viscosity exceeds 150 Pa·s, the step of applying to the film or the step of impregnating the reinforcing fiber needs to be high temperature, which may affect the storage stability. A more preferable viscosity is 10 Pa·s or more and 140 Pa·s or less, and preferably 20 Pa·s or more and 130 Pa·s or less. Furthermore, as for the epoxy resin composition, like the precursor mixture, the haze value in the thickness direction when the thickness is 2 mm is preferably less than 30%, more preferably less than 20%, and more preferably less than 10%. %.

The epoxy resin composition sheet is obtained by applying an epoxy resin composition to a base film. Can be clipped with cover film if desired. Polyimide, polyethylene terephthalate, polybutylene terephthalate, polyethylene, paper, etc. are generally used for the base film. The base film may or may not be subjected to mold release treatment. In the case of paper, mold release treatment is required. When a coverlay film is used, a release-treated polyethylene film or paper is usually used. The coating thickness is 10 μm or more and 300 μm or less, preferably 15 μm or more and 150 μm or less, and more preferably 20 μm or more and 100 μm or less. In the present invention, as will be described later, it may be bonded to a to-be-adhered body and thermally polymerized, or it may be impregnated into reinforcing fibers or the like. The thermal polymerization at this time is usually carried out in the range of 100°C to 200°C. When the thermal polymerization temperature is less than 100°C, the glass transition temperature of the polymer exceeds this temperature in the middle of the polymerization, so that the reaction does not proceed sufficiently. When the reaction is performed at more than 200°C, an undesired side reaction may occur and gelation may occur. The time required for the polymerization is usually 5 minutes to 6 hours. When the reaction temperature is high, the time is shortened, but when the reaction temperature is less than 5 minutes, the polymerization reaction does not proceed sufficiently. Moreover, when it exceeds 6 hours, since productivity deteriorates, it is unpreferable.

The thermoplastic epoxy resin is a thermoplastic epoxy resin obtained by polymerizing an epoxy resin composition or an epoxy resin composition sheet. When an epoxy resin composition sheet is used, a sheet-like thermoplastic epoxy resin can be obtained. In order to express thermoplasticity, the solvent-insoluble content (gel fraction) must be 0% by weight or more and 10% by weight or less. The solvent-insoluble content (gel fraction) can be measured by the method described in Examples. In addition, the molecular weight of the thermoplastic epoxy resin is 5,000 or more, preferably 7,500 or more, and desirably 10,000 or more, in terms of number average molecular weight. When the number average molecular weight is less than 5,000, the degree of polymerization cannot be said to be sufficient for obtaining mechanical strength, and strength cannot be obtained. The upper limit is not particularly limited, but generally, when the number average molecular weight exceeds 30,000, it will be difficult for the polymerization to proceed, and one of 50,000 or less can be obtained. The weight average molecular weight is 50,000 or more, preferably 300,000 or less. The dispersion represented by the weight average molecular weight/number average molecular weight is preferably 1 or more and 20 or less, and desirably 2 or more and 15 or less. When the dispersion exceeds 20, it tends to gel easily. In addition, the dispersion will not be less than 1.

Reinforcing fibers are fibers for reinforcing the thermoplastic epoxy resin as the matrix resin, and examples thereof include carbon fibers, glass fibers, polyaramid fibers, and the like. In addition, the form of these fibers is not limited, and any form of long fibers, chopped fibers, nonwoven fabrics, and cloths may be used.

In the present invention, a prepreg (epoxy resin prepreg) refers to a composite of an epoxy resin composition or an epoxy resin composition sheet and a reinforcing fiber. If the voids remain during the impregnation, there is a possibility that the final product may be defective and the desired strength cannot be exhibited. Therefore, it is desirable to reduce the voids during the impregnation. As a method thereof, heat treatment can be performed. The heat treatment is usually performed at 50°C or higher and 100°C or lower. When the temperature is lower than 50°C, the viscosity of the resin cannot be sufficiently reduced, and impregnation failure may occur. When it exceeds 100 degreeC, a polymerization reaction may progress. The time of heat treatment is usually 5 seconds or more and 3 minutes or less. In the case of less than 5 seconds, depending on the thickness, sufficient viscosity reduction and impregnation may not be performed. If it exceeds 3 minutes, the polymerization reaction may progress slightly, and the desired viscosity may not be obtained. In addition, as a method of further improving the impregnation accuracy, thermocompression bonding by a hot roll or the like can be mentioned. Although the pressure also depends on the base material, it is 0.1 kgf/cm or more and 10 kgf/cm or less. When the linear pressure is less than 0.1 kgf/cm, the impregnation may become insufficient, and when it exceeds 10 kgf/cm, the reinforcing fibers may be damaged or the resin may flow out. The volume ratio of resin and reinforcing fibers is 30:70 to 80:20. When the resin ratio is less than 30, there is a problem of insufficient resin and increased voids. When the resin ratio exceeds 80, since the amount of reinforcing fibers becomes small, sufficient characteristics cannot be obtained.

In the present invention, the so-called in-situ polymerized thermoplastic fiber-reinforced plastic is obtained by thermally polymerizing an epoxy resin prepreg. The molecular weight is 5,000 or more in terms of number average molecular weight (Mn), preferably 7,500 or more, and desirably 10,000 or more. When the number average molecular weight is less than 5,000, the degree of polymerization cannot be said to be sufficient for obtaining mechanical strength, and strength cannot be obtained. The upper limit is not particularly limited, but generally, when the number average molecular weight exceeds 30,000, it will be difficult for the polymerization to proceed, and one of 50,000 or less can be obtained. The weight average molecular weight (Mw) is 50,000 or more, preferably 300,000 or less. The dispersion represented by the weight average molecular weight/number average molecular weight is preferably 1 or more and 20 or less, and desirably 2 or more and 15 or less. When the dispersion exceeds 20, it tends to gel easily. In addition, the dispersion will not be less than 1. [Example]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples at all. Unless otherwise specified, "parts" means parts by weight, and "%" means % by weight. In addition, the raw materials used in the following examples are as follows.

[Epoxy resin] A1: Tetramethylbisphenol F-type epoxy resin (manufactured by NIPPON STEEL Chemical & Material Co., Ltd., YSLV-80XY, epoxy equivalent 192 g/eq) A2: Tetramethyl biphenol type epoxy resin (manufactured by Mitsubishi Chemical Co., Ltd., YX4000, epoxy equivalent 188 g/eq) A3: Bisphenol A type liquid epoxy resin (manufactured by NIPPON STEEL Chemical & Material Co., Ltd., YD-128, epoxy equivalent 188 g/eq)

[Phenolic compound] B1: Bisphenol A (manufactured by NIPPON STEEL Chemical & Material Co., Ltd.) B2: 4,4'-(3,3,5-trimethylcyclohexylene) bisphenol (manufactured by Honshu Chemical Industry Co., Ltd., BisP-HTG) B3: 9,9-bis(4-hydroxy-3-methylphenyl)fluorene (manufactured by Osaka Gas Chemical Co., Ltd., BCF)

[Organic solvents] C1: Cyclohexanone (reagent grade 1, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[polymerization catalyst] E1: 2,3-Dihydro-1H-pyrrolo-[1,2-a]benzimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., TBZ) E2: Tris(p-tolyl)phosphine (manufactured by Beixing Chemical Industry Co., Ltd., TPTP) E3: Tris(p-methoxyphenyl)phosphine (manufactured by Beixing Chemical Industry Co., Ltd., TPAP)

[reinforced fiber] I1: PAN-based carbon fiber (manufactured by Toray Co., Ltd., T700SC-12K-60E)

Example 1 278.1 parts of A1, 50.0 parts of B1, and 150.0 parts of B2 were respectively weighed, and pulverized and mixed using a Henschel mixer. Next, melt-mixing was carried out using an S1KRC kneader (manufactured by Kurimoto Iron Works Co., Ltd.) with a barrel temperature preheated to 170° C., the total amount was collected in a metal can, and it was cooled while stirring to obtain a thermoplastic epoxy resin. The precursor mixture (D1).

The obtained precursor mixture (D1) was placed in a colorless and transparent glass petri dish so as to have a thickness of 2 mm, referring to the haze standard plate manufactured by the Murakami Color Technology Research Institute, according to "less than 5% (<5) ""5% or more and less than 10% (<10)" "10% or more and less than 20% (<20)" "20% or more and less than 30% (<30)" "30% or more (30≦)" Five The haze value in the thickness direction was evaluated in two stages, and the result was less than 10%.

The viscosity at 60°C of the obtained precursor mixture (D1) was measured using CV-1s manufactured by Toa Kogyo Co., Ltd. and found to be 25 Pa·s.

The weight average molecular weight (Mw) of the obtained precursor mixture (D1) was 371. In addition, the measuring method of Mw is as follows. Analysis was performed using HLC-8420GPC manufactured by Tosoh Co., Ltd. The column was connected in series with TSKgel G4000HXL, TSKgel G3000HXL, and TSKgel G2000HXL, and the column oven was set to 40°C. The eluate was set to tetrahydrofuran, and the detector was set to an RI detector. Regarding the flow rate, it was set to 1 mL/min on the sample side and 0.5 mL/min on the reference side. About 0.05 g of the sample was weighed, dissolved in 10 mL of tetrahydrofuran containing 5% cyclohexanone as an external standard material, and filtered through a 0.45 μm polytetrafluoroethylene (PTFE) membrane filter, and the obtained for analysis. The Mw was converted using a standard polystyrene calibration curve, and the dissolution time was corrected using cyclohexanone.

Example 2 to Example 6, Comparative Example 1 to Comparative Example 3 According to the conditions described in Table 1, a thermoplastic epoxy resin precursor mixture was obtained by the same operation as in Example 1. However, regarding the operation of Example 5 and Comparative Examples 1 to 3, instead of mixing with a Henschel mixer, mixing was performed with an autorotation revolution type centrifugal stirring device, and then melt-mixing was performed with a kneader. The haze value, viscosity, and Mw of the obtained precursor mixture were measured in the same manner as in Example 1, and Table 1 shows the measurement results. In addition, in Comparative Example 2, although the liquid ejected from the kneader was transparent, crystals were precipitated during stirring in the cooling step, and turbidity occurred in the sample. In addition, in the process of measuring the viscosity at 60°C, the crystals continued to precipitate and were unstable, so the measurement could not be performed.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 A1 278.1 301.1 A2 294.8 271.9 228.4 188.0 A3 69.4 188.0 188.0 188.0 B1 50.0 100.0 100.0 50.0 150.0 112.0 112.0 112.0 106.0 B2 150.0 100.0 100.0 150.0 25.0 B3 25.0 Drum temperature (℃) 170 160 160 160 140 160 160 140 170 precursor mixture D1 D2 D3 D4 D5 D6 DH1 DH2 DH3 Haze value (%) <10 <5 <10 <10 <10 <10 <10 <30 <5 Viscosity (Pa s) 25 12 11 29 16 4 1.4 - 0.4 Mw 371 364 347 344 339 338 413 404 375

Table 1 will be described below. Regarding Examples 1 to 6 and Comparative Examples 1 to 3, the precursor mixtures that were uniformly dissolved and were liquid at 60° C. and semisolid to liquid at room temperature were obtained. In Comparative Example 2, bisphenol A (BPA) is considered to cause recrystallization. In Comparative Example 1, it seems that BPA also caused recrystallization, but it was not found in this experiment. In Comparative Example 1, it is considered that the thermal history is severe, and there is a possibility that a part of the resin component deteriorates and crystallization is inhibited. In addition, it was shown that the precipitation of crystals at room temperature can be effectively suppressed by mixing two or more phenol compounds.

Example 7 1 part of E1 (polymerization catalyst) was dissolved in 1 part of C1 (organic solvent) in advance. The precursor mixture (D1) obtained in Example 1 was placed in a planetary mixer set at 60°C, and the previous polymerization catalyst solution was added and mixed. After mixing, it was quickly taken out and immediately cooled to 40° C. or lower to obtain an epoxy resin composition (F1).

The viscosity at 60° C. of the obtained epoxy resin composition (F1) was measured using MCR102 manufactured by Anton Paar, and found to be 62 Pa·s. In addition, the haze value of the epoxy resin composition is 5% or more and less than 10% (<10).

In addition, the obtained epoxy resin composition (F1) was heated and stirred to about 70°C, poured into an iron chrome-plating mold container with a gap of 4 mm in advance, and carried out in a hot air circulation oven at 160°C for 4 It is thermally polymerized for hours to obtain a thermoplastic epoxy resin.

The epoxy equivalent of the obtained thermoplastic epoxy resin was measured in accordance with Japanese industrial standard (JIS) K 7236 and found to be 18,000 g/eq.

In addition, the glass transition temperature (Tg) of the thermoplastic epoxy resin was 123°C. In addition, the measuring method of Tg is as follows. According to JIS K 7121, the differential scanning calorimeter (Hitachi High-Tech Science Co., Ltd., EXSTAR6000 DSC6200) was used to measure the temperature at a temperature of 10°C/min. (The middle temperature of the variation curve with respect to the tangent of the glass state and the rubber state) is represented by the temperature.

In addition, the gel fraction of the thermoplastic epoxy resin is 1% by weight or less. In addition, the measuring method of a gel fraction is as follows. Precisely weigh about 1 g of thermoplastic epoxy resin as a sample in a 100 mL vial, add 50 mL of tetrahydrofuran, carry out ultrasonic diffusion at room temperature for 1 hour, and then stand at room temperature for 23 hours Dissolution is performed above. In addition, the 500-mesh metal mesh was dried in an oven at 100° C. for 1 hour, and its weight was measured. The 500-mesh metal mesh was folded into a funnel shape, and the total amount of the sample solution was poured onto the funnel. Wash with tetrahydrofuran until the insoluble matter of the sample does not remain in the vial, flow into the funnel, and then wash the net insoluble matter and net with tetrahydrofuran, and then dry in an oven at 100° C. for more than 4 hours. The dry weight of the web was subtracted from the weight of the dried sample and the web, and divided by the weight of the sample to obtain the gel fraction in % by weight.

In addition, the number average molecular weight (Mn), weight average molecular weight (Mw), and peak top molecular weight (Mt) of the thermoplastic epoxy resin were 25,000, 62,000, and 35,000, respectively. In addition, the measuring method of molecular weight is as follows. Analysis was performed using HLC-8320GPC manufactured by Tosoh Co., Ltd. The column was connected in series with TSKguardcolumnHXL, TSKgel GMHXL, TSKgel GMHXL and TSKgel G2000HXL, and the column oven was set to 40°C. The eluate was set to tetrahydrofuran, and the detector was set to an RI detector. Regarding the flow rate, it was set to 1 mL/min on the sample side and 0.5 mL/min on the reference side. Measure about 0.1 g of thermoplastic epoxy resin as a sample, dissolve it in 10 mL of tetrahydrofuran containing 5% cyclohexanone as an external standard material, filter it with a 0.45 μm PTFE membrane filter, and use the obtained sample as a for analysis. The molecular weight was converted using a standard polystyrene calibration curve, and the dissolution time was corrected using cyclohexanone.

In addition, regarding the external appearance in Table 2, the case where a crack was confirmed in the test piece edge part in the cooling step after the polymerization of thermoplastic epoxy resin was made into x, and the thing which did not change was made into (circle).

Example 8 to Example 12, Comparative Example 4 to Comparative Example 6 According to the conditions described in Table 2, an epoxy resin composition and a thermoplastic epoxy resin were obtained by the same operation as in Example 7. The melt viscosity and haze value of the obtained epoxy resin composition, appearance of thermoplastic epoxy resin, epoxy equivalent, gel fraction, Tg, Mn, Mw, and Mt were measured in the same manner as in Example 7, and The measurement results are shown in Table 2.

[Table 2] Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Comparative Example 4 Comparative Example 5 Comparative Example 6 Precursor D1 D2 D3 D4 D5 D6 DH1 DH2 DH3 (allocation amount) 100 100 100 100 100 100 100 100 100 E1 1 1 E2 1 E3 1 1 1 1 1 1 C1 1 1 1 1 1 1 1 1 1 epoxy resin composition F1 F2 F3 F4 F5 F6 FH1 FH2 FH3 Viscosity (Pa s) 62 35 32 89 41 14 4 4 1 Haze value (%) <10 <5 <10 <10 <10 <10 <10 <30 <10 Exterior 〇 〇 〇 〇 〇 〇 〇 〇 × Epoxy equivalent (g/eq) 18000 22000 24000 154000 12000 15000 - - 5200 Tg (℃) 123 114 127 138 110 113 93 93 90 Gel fraction (%) <1 <1 <1 <1 2 <1 55 17 5 Mn 25000 32000 28000 21000 19000 18000 13000 18000 6800 Mw 62000 120000 80000 62000 94000 71000 160000 128000 43000 Mt 35000 39000 40000 29000 31000 27000 22000 24000 12000

Table 2 will be described. In Examples 7 to 12, resin compositions with a viscosity suitable for the hot-melt process can be obtained. In addition, in the polymer, gelation was hardly confirmed. In both Comparative Example 4 and Comparative Example 5, a gel component was clearly generated in the thermoplastic epoxy resin. In Comparative Example 4 and Comparative Example 5, the steric hindrance around the glycidyl group was small, and thermally degraded components were generated in the heating dissolving step or the thermal polymerization step, and gelation was likely to occur during polymerization. In Examples 7 to 12 in which the steric hindrance around the glycerol group was large, gelation was hardly caused. In addition, with regard to Comparative Example 6, it is considered that since the polymerization did not proceed sufficiently, it was not gelled.

Example 13 The release paper subjected to the release treatment was fixed on a hot plate preheated to 70° C. with the release surface facing up, and the epoxy resin composition (F1) obtained in Example 6 was placed on the release surface. On the paper, it was coated so as to have a thickness of 50 μm using a bar coater preheated to 70°C. Immediately after coating, it was taken off from the hot plate and air-cooled to obtain an epoxy resin composition sheet. Next, carbon fibers (I1) were attached to the obtained epoxy resin composition sheet so as to have a strand density of 15 per 10 cm, and the surface pressure was 0.5 MPa using a hot press preheated to 90°C. The pressure was applied in the manner of 1 minute, and it was taken out and air-cooled to obtain an epoxy resin prepreg with Rc=33%. Furthermore, after 9 sheets of the obtained epoxy resin prepreg bulk layers are sandwiched by a mold release film, an in-situ polymerized thermoplastic fiber reinforced plastic is obtained by vacuum pressing. In addition, the conditions of vacuum pressing were set to 160 degreeC, 0.5 MPa, and 4 hours.

The gelation of the obtained thermoplastic fiber-reinforced plastic was judged, and as a result, it was not gelled. In addition, in the determination of gelation, about 0.1 g of the test piece, the resin component was dissolved by ultrasonic diffusion in 10 mL of tetrahydrofuran, and the loose carbon fiber bundle was determined to have no gel and was determined to be "0", and the If the carbon fiber bundle was not loosened, it was judged to be gelled and judged as "x".

In addition, Mn, Mw, and Mt of the thermoplastic fiber-reinforced plastic were 23,000, 76,000, and 33,000, respectively. In addition, the measuring method of the molecular weight was in accordance with the method described in Example 7.

Example 14 to Example 18, Comparative Example 7 to Comparative Example 9 A thermoplastic fiber-reinforced plastic was obtained by the same operation as in Example 13 except that the epoxy resin composition described in Table 3 was used. The determination of gelation, Mn, Mw, and Mt of the obtained thermoplastic fiber-reinforced plastic were performed in the same manner as in Example 13, and Table 3 shows the measurement results.

[table 3] Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Comparative Example 7 Comparative Example 8 Comparative Example 9 epoxy resin composition F1 F2 F3 F4 F5 F6 FH1 FH2 FH3 Determination of gelation 〇 〇 〇 〇 〇 〇 × × 〇 Mn 23000 27000 32000 22000 15000 23000 - - 6700 Mw 76000 108000 100000 69000 83000 68000 - - 50000 Mt 33000 34000 45000 27000 28000 28000 - - 16000

Table 3 will be described. In all of Examples 13 to 18, it was confirmed that the cured product was polymerized, and the fibers were dispersed when dissolved in tetrahydrofuran. On the other hand, in Comparative Example 7 and Comparative Example 8, it was hardly dissolved in tetrahydrofuran, and the fibers were not scattered. In Comparative Example 9, although it was dissolved in tetrahydrofuran, the degree of polymerization was insufficient, and the function as a structural material was not sufficient. [Industrial Availability]

The precursor mixture of the present invention can be used in epoxy resin compositions (sheets), and can be particularly preferably used in in-situ polymerized thermoplastic epoxy resins, prepregs, thermoplastic fiber reinforced plastics, and the like.

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Claims (15)

A precursor mixture, which is used in an in-situ polymerized thermoplastic epoxy resin obtained by addition polymerization of an epoxy resin and a difunctional phenolic compound, is characterized in that: The epoxy resin of the bifunctional epoxy resin (a) represented by the following formula (1), and the bifunctional phenol compound as essential components, with respect to 1 mol of the epoxy resin, the bifunctional phenol compound is 0.9 mol to 1.1 mol, the viscosity at 60°C is 1 Pa·s or more and 50 Pa·s or less,

Here, A in the formula (1) is the formula (2), n is the number of repetitions and the average value thereof is 0 to 5; X is a single bond, an alkylene group having 1 to 9 carbon atoms, -O-, -CO any one of -, -COO-, -S-, -SO ₂ -, Y ¹ is independently any one of an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 10 carbon atoms, Y ² and Y ³ is each independently any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 10 carbon atoms. The precursor mixture of claim 1, wherein the haze value in the thickness direction when the thickness is 2 mm is less than 30%. The precursor mixture according to claim 1 or claim 2, wherein the weight average molecular weight obtained by a standard polystyrene calibration curve is 300 or more and 500 or less. The precursor mixture according to claim 1 or claim 2, wherein the difunctional phenol compound is a bisphenol compound and/or a biphenol compound. The precursor mixture according to claim 1 or claim 2, wherein the ratio of the largest component in the difunctional phenol compound is 90% by weight or less. An epoxy resin composition prepared by mixing the precursor mixture according to any one of claim 1 to claim 5 with a polymerization catalyst, and being compatible with each other. The epoxy resin composition according to claim 6, wherein the haze value in the thickness direction when the thickness is 2 mm is less than 30%. The epoxy resin composition according to claim 6 or claim 7, wherein the viscosity at 60° C. is 3 Pa·s or more and 150 Pa·s or less. An in-situ polymerized thermoplastic epoxy resin obtained by polymerizing the epoxy resin composition according to any one of Claims 6 to 8. The in-situ polymerization thermoplastic epoxy resin according to claim 9, wherein the gel fraction is 0 wt % or more and 10 wt % or less. An epoxy resin composition sheet, which is obtained by making the epoxy resin composition according to any one of Claims 6 to 8 into a thickness of 10 μm or more and 300 μm or less. A sheet-like in-situ polymerization thermoplastic epoxy resin obtained by polymerizing the epoxy resin composition sheet according to claim 11. The sheet-like in-situ polymerization thermoplastic epoxy resin according to claim 12, wherein the gel fraction is 0 wt % or more and 10 wt % or less. A prepreg obtained from the epoxy resin composition according to any one of claim 6 to claim 8 and/or the epoxy resin composition sheet according to claim 11, and reinforcing fibers . An in-situ polymerized thermoplastic fiber-reinforced plastic is obtained by polymerizing the prepreg described in claim 14.