JP2015052070A - Phosphorus-containing epoxy resin and composition and hardened product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phosphorus-containing epoxy resin which is free of bleeding out while allowing arbitrary adjustment of the phosphorus content through the addition amount, similar to addition-type phosphorus-based flame retardants, and is excellent in solvent solubility and impregnation properties.SOLUTION: A phosphorus-containing epoxy resin has an epoxy equivalent of 1,000-5,000 g/eq and an active hydrogen equivalent of 1,000-5,000 g/eq, in a ratio of the equivalent of active hydrogen groups to 1 equivalent of epoxy groups of 0.95-1.05 eq. An epoxy resin composition containing the phosphorus-containing epoxy resin and other epoxy resins and a hardened product of the composition are also provided.

Description

  The present invention relates to a phosphorus-containing epoxy resin having flame retardancy useful for laminates for electric and electronic circuits, insulating films, adhesives, insulating paints, resist materials, sealing materials, casting materials, etc., and compositions and cured products thereof. It is about.

  Epoxy resins are widely used because they have excellent adhesion, heat resistance, and moldability, such as laminates for electrical and electronic equipment, sealants, automotive parts, fiber reinforced plastics (FRP), and sports equipment. In particular, insulating materials such as laminates and film materials used in electrical and electronic equipment are strongly required to impart flame retardancy. As a flame retardant method, a so-called halogen-free flame retardant system that does not use a halide is being transferred from a conventional bromine-based flame retardant system due to an increase in environmental problems. In contrast to this, phosphorus compounds are mainly proposed, but safety is insufficient when red phosphorus is used as an additive-type phosphorus flame retardant, and the surface of a cured product when phosphoric acid compounds are used. There was a problem bleeding out.

For the above problem, 10- (2,5-dihydroxyphenyl) -10H-9-oxa-10-phosphaphenanthrene-10-oxide (trade name HCA-HQ, manufactured by Sanko Co., Ltd.) and epoxy resins Thermosetting resins and compositions obtained by reacting at a predetermined molar ratio are disclosed (Patent Documents 1 and 2). Further, a phosphorus-containing epoxy resin obtained by reacting a resin having a bifunctional or higher functional epoxy group with diphenylphosphinyl hydroquinone is disclosed (Patent Document 3). Moreover, phosphorus containing polyhydroxy ether resin is disclosed (patent document 4). The danger of using red phosphorus by using such a reactive phosphorus compound, the problem of bleeding out when adding an additive type phosphorus compound, the solder heat resistance when using phosphate esters, Problems such as a decrease in solvent resistance have been solved. However, the phosphorus-containing epoxy resin and phosphorus-containing polyhydroxy polyether resin obtained by the reaction between such a phosphorus compound and an epoxy resin have a high molecular weight as the phosphorus content increases, so that sufficient flame retardancy is obtained. The resulting resin has a high viscosity, and there is a problem that workability and impregnation into a substrate such as glass cloth are deteriorated. These problems are dealt with by using a reactive diluent in combination, but physical properties are reduced due to the influence of the reactive diluent used together (Patent Document 3).
Also disclosed is a phosphorus-containing epoxy resin in which the epoxy resin (a) and the compound (b) having a reactive functional group containing a phosphorus-containing phenol compound as essential components are in the range of 60% to 95% of the theoretical epoxy equivalent. In addition, a method is disclosed in which the molecular weight is kept low and the viscosity is lowered by having an epoxy group and a phenolic hydroxyl group as terminal reactive groups (Patent Document 5). However, even in this method, since the compounding ratio is determined by the epoxy equivalent, in order to adjust to the desired phosphorus content, it is necessary to review including the curing agent, and it is difficult to adjust the phosphorus content .

Japanese Patent No. 3092009 Japanese Patent No. 3268498 Japanese Patent Laid-Open No. 5-214070 JP 2001-310939 A JP 2012-172079 A

  The present invention is a phosphorus-containing epoxy having an excellent solvent solubility and impregnation property without any bleed-out problem, although the phosphorus content can be arbitrarily adjusted by adjusting the addition amount in the same manner as the additive type phosphorus flame retardant. Resin is provided.

  The inventors of the present invention have made the phosphorus-containing epoxy resin have good solvent solubility and impregnation property by keeping the epoxy equivalent and active hydrogen equivalent of the resin within a certain range and making this equivalent ratio almost equal. Was found to be possible, and the present invention was completed.

  That is, according to the present invention, in the phosphorus-containing epoxy resin having an epoxy group and an active hydrogen group, the epoxy equivalent is in the range of 1000 to 5000 g / eq, the active hydrogen equivalent is in the range of 1000 to 5000 g / eq, and The phosphorus-containing epoxy resin is characterized in that the active hydrogen group is in the range of 0.95 to 1.05 equivalent to 1 equivalent of epoxy group.

  In addition, the present invention is obtained by reacting an epoxy resin (a) with an active hydrogen group-containing compound (c) containing a phosphorus compound (b) having an active hydrogen group as an essential component. This is a phosphorus-containing epoxy resin.

（ここで、Ｒ₁、Ｒ₂、Ｒ₃及びＲ₄は炭素数１〜６の炭化水素基を表し、同一であっても異なっていてもよく、Ｒ₁及びＲ₂、またはＲ₃及びＲ₄はリン原子と共に環状構造を形成してもよい。ｊ、ｋは０または１を表す。Ａは炭素数６〜２０の３価の芳香族炭化水素基を表す。） The phosphorus compound (b) having an active hydrogen group can be a phosphorus compound (b1) represented by the general formula (1), a phosphorus compound (b2) represented by the general formula (2), or both.

(Here, R ₁ , R ₂ , R ₃ and R ₄ represent a hydrocarbon group having 1 to 6 carbon atoms and may be the same or different, and R ₁ and R ₂ , or R ₃ and R 4 ₄ may form a cyclic structure with a phosphorus atom, j and k each represents 0 or 1. A represents a trivalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

  The ratio of the epoxy resin (a) to the active hydrogen group-containing compound (c) is set such that the active hydrogen group-containing compound (c) has an active hydrogen group ratio of 0.95 to 1.5 with respect to 1 equivalent of the epoxy group of the epoxy resin (a). A range of 05 equivalents is preferred. Moreover, a phenolic hydroxyl group is mentioned as an active hydrogen group.

  The present invention also provides a phosphorus-containing epoxy resin composition comprising the above-described phosphorus-containing epoxy resin as a part of the epoxy resin in a phosphorus-containing epoxy resin composition containing an epoxy resin and a curing agent (C). It is.

  Furthermore, the present invention is a prepreg obtained by impregnating a fibrous base material with the above phosphorus-containing epoxy resin composition, and is a cured product obtained by curing the above phosphorus-containing epoxy resin composition or prepreg.

  Since the phosphorus-containing epoxy resin of the present invention has almost the same number of epoxy groups and active hydrogen groups in the same resin, it can be cured by itself. Moreover, a phosphorus content rate can be adjusted and a flame retardance can be improved by mix | blending the phosphorus containing epoxy resin of this invention in the epoxy resin composition which does not have flame retardance, or is inadequate. At this time, there is no need to consider the epoxy equivalent or active hydrogen equivalent of the phosphorus-containing epoxy resin. That is, although it is a reactive phosphorus-containing epoxy resin, it can be used like an additive-type flame retardant. Moreover, since the phosphorus-containing epoxy resin of the present invention reacts with the epoxy resin and the curing agent in the epoxy resin composition, there is no bleed-out problem unlike the additive type flame retardant.

3 is a GPC chart of the phosphorus-containing epoxy resin of the present invention. 3 is an IR chart of the phosphorus-containing epoxy resin of the present invention.

Hereinafter, embodiments of the present invention will be described in detail.
The phosphorus-containing epoxy resin of the present invention has an epoxy group and an active hydrogen group, has an epoxy equivalent in the range of 1000 to 5000 g / eq, an active hydrogen equivalent in the range of 1000 to 5000 g / eq, The equivalent / epoxy equivalent ratio is in the range of 0.95 to 1.05. The active hydrogen group is a functional group having an active hydrogen reactive with an epoxy group, and specifically includes a carboxyl group, an amino group, a phenolic hydroxyl group, and the like, and among them, a phenolic hydroxyl group is preferable. In addition, regarding an active hydrogen group, 1 mol of carboxyl groups and phenolic hydroxyl groups are calculated as 1 equivalent, and an amino group (NH ₂ ) is calculated as 2 equivalents.

  The phosphorus-containing epoxy resin of the present invention is obtained by reacting an epoxy resin (a) with an active hydrogen group-containing compound (c) whose essential component is a phosphorus compound (b) having an active hydrogen group. The phosphorus compound (b) having a phosphorus compound (b1) represented by the general formula (1) or the phosphorus compound (b2) represented by the general formula (2) from the viewpoints of heat resistance, water resistance and the like Is more preferable.

  The epoxy resin (a) is not particularly limited as long as it is a known epoxy resin, but preferably has an average of 1 to 4 epoxy groups in the molecule, and an average of 1.5 to 3.0 in the molecule. Those having an epoxy group of 1 are more preferred, and those having an average of about 1.8 to 2.2 epoxy groups in the molecule are more preferred. Particularly preferred is a bifunctional epoxy resin. If the number of epoxy groups is less than one, the functional groups are reduced during the reaction with the active hydrogen group-containing compound (c) and the polymer is not polymerized. Since the viscosity of the phosphorus-containing epoxy resin obtained without gelation sometimes increases, the impregnation property and workability are adversely affected.

  Specific examples of the epoxy resin (a) include Epototo YD-128, Epototo YD-8125, Epototo YD-825GS (Bisphenol A type epoxy resin manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), Epototo YDF-170, Epototo YDF-170B. , Epototo YDF-8170, YDF-870GS (Nippon Steel & Sumikin Chemical Co., Ltd. bisphenol F type epoxy resin), YSLV-80XY (Nippon Steel & Sumikin Chemical Co., Ltd. tetramethylbisphenol F type epoxy resin), Epototo YDC-1312 (Nippon Steel & Sumikin Chemical) Hydroquinone type epoxy resin manufactured by Co., Ltd.), jERYX4000H (biphenyl type epoxy resin manufactured by Mitsubishi Chemical Co., Ltd.), Epototo YDPN-638, Epototo YDPN-63X (Phenol Novo manufactured by Nippon Steel & Sumikin Co., Ltd.) Type epoxy resin), Epototo YDCN-701 (Cresol novolak type epoxy resin manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), Epototo ZX-1201 (Bisphenol fluorene type epoxy resin manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), TX-0710 (Nippon Steel & Sumikin Chemical Co., Ltd.) Bisphenol S type epoxy resin manufactured by Co., Ltd.), Epicron EXA-1515 (Bisphenol S type epoxy resin manufactured by Dainippon Chemical Industry Co., Ltd.), NC-3000 (Biphenyl aralkyl phenol type epoxy resin manufactured by Nippon Kayaku Co., Ltd.), Epototo ZX- 1355, Epototo ZX-1711 (Naphthalenediol type epoxy resin manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), Epototo ESN-155 (β-naphthol aralkyl type epoxy resin manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), Epototo ESN -355, Epototo ESN-375 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., dinaphthol aralkyl epoxy resin), Epototo ESN-475V, Epototo ESN-485 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., α-naphthol aralkyl epoxy resin), EPPN-501H (Nippon Kayaku Co., Ltd. trisphenylmethane type epoxy resin), Sumiepoxy TMH-574 (Sumitomo Chemical Co., Ltd. trisphenylmethane type epoxy resin), YSLV-120TE (Nippon Steel & Sumikin Chemical Co., Ltd. bisthioether type epoxy resin), There are epoxy resins such as Epototo ZX-1684 (Resorcinol type epoxy resin manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) and Epicron HP-7200H (Dicyclopentadiene type epoxy resin manufactured by DIC Corporation). Furthermore, TX-0929, TX-0934, TX-1032 (alkylene glycol type epoxy resin manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), Celoxide 2021 (aliphatic cyclic epoxy resin manufactured by Daicel Chemical Industries, Ltd.), Epototo YH-434, (Nippon Steel) There are epoxy resins such as diaminodiphenylmethanetetraglycidylamine manufactured by Sumikin Chemical Co., Ltd. Furthermore, jER630 (Mitsubishi Chemical Co., Ltd. aminophenol type epoxy resin), Epototo FX-289B, Epototo FX-305, TX-0932A (Nippon Steel & Sumikin Chemical Co., Ltd. phosphorus-containing epoxy resin), urethane-modified epoxy resin, oxazolidone ring-containing Examples include, but are not limited to, epoxy resins. These epoxy resins may be used alone or in combination of two or more.

  The phosphorus compound (b) having an active hydrogen group is phosphoric acid, acidic phosphoric acid ester, acidic phosphoric acid monoester, acidic phosphorous acid diester, the phosphorus compound (b1) represented by the general formula (1), or the above And having an active hydrogen group reactive with an epoxy group such as the phosphorus compound (b2) represented by the general formula (2). Specifically, methyl acid phosphate (mixture average molecular weight = 119, Daihachi Chemical Industry AP-1; Sakai Chemical Industry Phoslex A-1), ethyl acid phosphate (mixture average molecular weight = 139, Sakai Chemical Industry Co., Ltd.) Phoslex A-2, Johoku Chemical Industry JP-501), isopropyl acid phosphate (average molecular weight of mixture = 161, Sakai Chemical Industry's Phoslex A-3), butyl acid phosphate (average molecular weight of mixture = 182, Sakai Chemical Industry's Phoslex A- 4, Daihachi Chemical Industry AP-4, Johoku Chemical Industry JP-504), dibutyl phosphate (single product, molecular weight = 210, Daihachi Chemical Industry DP-4, Johoku Chemical Industry DBP), monobutyl phosphate (single product) And molecular weight = 154, MP-8 manufactured by Daihachi Chemical Industry, Buto Cyethyl acid phosphate (mixture, JP-508H manufactured by Johoku Chemical Industry Co., Ltd.), 2-ethylhexyl acid phosphate (average molecular weight of the mixture = 266, Phoslex A-8 manufactured by Sakai Chemical Industry Co., Ltd., AP-8 manufactured by Daihachi Chemical Industry Co., Ltd. JP-508), bis (2-ethylhexyl) phosphate (single product, molecular weight = 322, DP-8R manufactured by Daihachi Chemical Industry, LB-58 manufactured by Johoku Chemical Industry, Phoslex A-208 manufactured by Sakai Chemical Industry), isodecyl acid phosphate ( Average molecular weight of mixture = 308, Phoslex A-10 manufactured by Sakai Chemical Industry, AP-10 manufactured by Daihachi Chemical Industry, monoisodecyl acid phosphate (single product, molecular weight = 238, MP-10 manufactured by Daihachi Chemical Industry), lauryl acid phosphate (Average molecular weight of mixture = 355, Ph made by Sakai Chemical Industry slexA-12), tridecyl acid phosphate (average molecular weight of the mixture = 371, Phoslex A-13 manufactured by Sakai Chemical Industry), stearyl acid phosphate (average molecular weight of the mixture = 437, Phoslex A-18 manufactured by Sakai Chemical Industry), isostearyl acid phosphate (Molecular average in the mixture = 437, Phoslex A-180L manufactured by Sakai Chemical Industry), oleyl acid phosphate (average molecular weight in the mixture = 467, Phoslex A-18D manufactured by Sakai Chemical Industry, JP-518D manufactured by Johoku Chemical), Butyl pyrophosphate (Johoku Chemical) JP-504A), Tetracosyl Acid Phosphate (JP-524, Johoku Chemical), Ethylene Glycol Acid Phosphate (EGAP, Johoku Chemical), (2-Hydroxyethyl) Methacrylate Acid Phosphate (JPA-514 manufactured by Johoku Chemical Co., Ltd.) and the like can be mentioned, but are not limited thereto.

Among the phosphorus compounds (b) having an active hydrogen group, the phosphorus compound (b1) represented by the general formula (1) or the phosphorus compound (b2) represented by the general formula (2) is more preferable. In the general formulas (1) and (2), R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrocarbon group having 1 to 6 carbon atoms, preferably an alkyl group or a phenyl group, and may be the same or different. R ₁ and R ₂ , or R ₃ and R ₄ may form a cyclic structure with a phosphorus atom. j and k each represents 0 or 1; A represents a trivalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

  Examples of the aromatic hydrocarbon ring represented by A include a benzene ring and a condensed polycyclic aromatic hydrocarbon ring. The condensed polycyclic aromatic hydrocarbon ring includes a condensed bicyclic hydrocarbon (for example, a condensed bicyclic hydrocarbon having 8 to 20 carbon atoms such as indene and naphthalene, preferably a condensed bicyclic ring having 10 to 16 carbon atoms). And condensed 2-4 cyclic aromatic hydrocarbon rings such as condensed tricyclic hydrocarbons (for example, anthracene, phenanthrene, etc.). Preferred examples of the condensed polycyclic aromatic hydrocarbon ring include a naphthalene ring and an anthracene ring, and a naphthalene ring is particularly preferable. Each ring may have a methyl group or a phenyl group as a substituent.

  Specifically, the phosphorus compounds represented by the general formulas (1) and (2) are 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Co., Ltd., trade name HCA), Phosphorus compounds having an active hydrogen group directly bonded to a phosphorus atom, such as diphenylphosphine, and 10- (2,5-dihydroxyphenyl) -10H-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Co., Ltd., products Name HCA-HQ), 10- (1,4-dioxynaphthalene) -10H-9-oxa-10-phosphaphenanthrene-10-oxide (hereinafter DOPO-NQ), diphenylphosphinylhydroquinone (Hokuko Chemical Co., Ltd.) Product name PPQ), diphenylphosphenyl-1,4-dioxynaphthalene, 1,4-cyclooctylene phosphite 1,4-phenyldiol (trade name CPHO-HQ, manufactured by Nippon Chemical Industry Co., Ltd.), 1,5-cyclooctylenephosphinyl-1,4-phenyldiol (trade name, manufactured by Nippon Chemical Industry Co., Ltd.) And phosphorus-containing phenols such as CPHO-HQ). The phosphorus compound (b) is not limited to those exemplified. These phosphorus compounds may be used alone or in combination of two or more.

  For the reaction of the active hydrogen group-containing compound (c) having the epoxy resin (a) and the phosphorus compound (b) having an active hydrogen group as essential components, a known reaction method of an epoxy resin can be applied. That is, the reaction is carried out by stirring at a reaction temperature of 60 to 200 ° C., preferably 100 to 180 ° C. When the temperature is lower than 60 ° C., the reaction time becomes longer and it is not economical, and at a temperature higher than 200 ° C., it becomes difficult to control the epoxy equivalent and the active hydrogen equivalent.

  In the reaction, the epoxy resin (a) and the active hydrogen group-containing compound (c) may be charged and reacted at once, or the active hydrogen group-containing compound (c) may be added and divided into several times.

  A catalyst may be used for the reaction as necessary. As the catalyst, known and publicly used catalysts used in the production of epoxy resins can be used. Catalysts that can be used include phosphines such as triphenylphosphine and tris (2,6-dimethoxyphenyl) phosphine, quaternary phosphonium salts such as n-butyltriphenylphosphonium bromide and ethyltriphenylphosphonium iodide, 2-ethyl- Examples of known catalysts include imidazoles such as 4-methylimidazole and 2-phenylimidazole, quaternary ammonium salts such as tetramethylammonium chloride and tetraethylammonium bromide, and tertiary amines such as triethylamine and benzyldimethylamine. It is not limited to these. The amount of these catalysts used is preferably in the range of 0.005 to 1% by mass relative to the total amount of the active hydrogen group-containing compound (c).

  The proportion of the phosphorus compound (b) in the active hydrogen group-containing compound (c) is 3 wt% or more, preferably 5 to 100 wt%. When the ratio of the phosphorus compound (b) is large, the obtained epoxy resin has a large flame retardant effect, so that it can be used together with an epoxy resin having inferior flame retardancy to form a flame retardant epoxy resin composition. Moreover, even if the ratio of a phosphorus compound (b) is small, it can be set as a flame-retardant epoxy resin composition using only this epoxy resin or a small amount of other epoxy resins. In the additive type flame retardant, if the phosphorus content is high, the addition amount may be small, and the influence of the flame retardant on the physical properties of the cured product is reduced. However, in the case of the phosphorus-containing epoxy resin of the present invention, it reacts and cures at the time of curing. Since it is integrated with the product, the effect of the flame retardant on the physical properties of the cured product is small, it can be blended in large amounts, and the need for increasing the phosphorus content is less than that of the additive-type flame retardant.

  From another viewpoint, when only the phosphorus-containing epoxy resin of the present invention is used as an epoxy resin, the phosphorus compound (b) having an active hydrogen group so that the phosphorus content of the phosphorus-containing epoxy resin is in the range of 3 to 6% by mass. ) Amount may be adjusted. When the phosphorus content is less than 3% by mass, sufficient flame retardancy cannot be obtained, and when the phosphorus content is greater than 6% by mass, various physical properties such as solvent solubility, adhesive strength and heat resistance are deteriorated. However, when used in combination with other epoxy resins, the epoxy resin as a whole preferably satisfies the above range.

  When the active hydrogen group-containing compound (c) includes an active hydrogen group-containing compound (c3) other than the phosphorus compound (b), examples of the active hydrogen group-containing compound (c3) include the following compounds. Specifically, hydroxybenzenes such as catechol, resorcinol and hydroquinone, biphenols, binaphthols, trisphenols, dihydric phenols such as bisphenol A, bisphenol F and bisphenol S, Shonor BRG-555 (Showa Denko Co., Ltd.) Phenol novolak resin), cresol novolak resin, alkylphenol novolak resin, aralkyl phenol novolak resin, triazine ring-containing phenol novolak resin, biphenyl aralkyl phenol resin, Resitop TPM-100 (Trishydroxyphenylmethane type novolak resin manufactured by Gunei Chemical Industry Co., Ltd.) ), Compounds having two or more phenolic hydroxyl groups in one molecule such as aralkyl naphthalene diol resin, adipic acid dihydrazide, Hydrazides such as cyanodihydrazide, imidazole compounds and salts thereof, dicyandiamide, aminobenzoic acid esters, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, metaxylenediamine, isophoronediamine and other aliphatic amines, diaminodiphenylmethane, Aromatic amines such as diaminodiphenylsulfone and diaminoethylbenzene, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydro Examples thereof include acid anhydrides such as phthalic anhydride and methyl nadic anhydride, and two or more of these may be used.

  The active hydrogen group of the phosphorus-containing epoxy resin of the present invention may be an active hydrogen group of another reactive compound that can be used as long as the characteristics are not impaired. Moreover, the epoxy resin of the present invention may contain an unreacted epoxy resin (a) or an active hydrogen group-containing compound (c) as long as the above-mentioned properties such as epoxy equivalent are satisfied. In order to finely adjust the resin characteristics, a part of the raw material may be additionally mixed.

  The epoxy equivalent of the phosphorus-containing epoxy resin obtained by the reaction is in the range of 1000 to 5000 g / eq, the active hydrogen equivalent is in the range of 1000 to 5000 g / eq, and the active hydrogen group is equivalent to 1 equivalent of epoxy group. It is important to control the reaction so that is in the range of 0.95 to 1.05 equivalents.

  For the reaction control, the desired epoxy equivalent and active hydrogen equivalent can be obtained by adjusting the reaction temperature, the amount of catalyst, the reaction solvent, and the like. That is, the reaction rate is adjusted by lowering the reaction temperature and stopped at a predetermined reaction rate, or by adjusting the amount of catalyst, the reaction is stopped at a predetermined epoxy equivalent, or the dilution rate is changed by the reaction solvent. The reaction can be controlled. The reaction raw material is such that the equivalent ratio (active hydrogen group / epoxy group) of the epoxy group and the active hydrogen group of the epoxy resin (a) and the active hydrogen group-containing compound (c) is around 1.0, preferably 0.95 to 1.05. It is better to adjust the usage amount. By setting the equivalence ratio to around 1.0, the amount of the epoxy groups remaining unreacted and the active hydrogen groups becomes almost the same, and the equivalence ratio is also reduced to 0.95 to 1.05.

  The reaction solvent is not particularly limited as long as it is non-reactive. Specifically, benzene, toluene, xylene, ethylbenzene, acetone, methyl ethyl ketone, methyl butyl ketone, dipropyl ketone, cyclopentanone, cyclohexanone, dialkyl ether, 2 -Ethoxyethyl ethyl ether, ethanol, 2-butoxyethanol, glycol ether, propylene glycol monomethyl ether, dioxane and the like can be mentioned. These reaction solvents may be used alone or in combination of two or more. The amount of these reaction solvents used is preferably 50% or less of the total mass of the reaction product.

  Further, the number average molecular weight (Mn) of the phosphorus-containing epoxy resin is not particularly limited, but is preferably 3000 or less, more preferably 2000 or less. In particular, when Mn exceeds 5000, the impregnation property and workability are adversely affected.

  When the phosphorus compound (b) having an active hydrogen group is only a divalent phenol compound represented by the general formula (2), 0.95 to 0.55 of a phenolic hydroxyl group per 1 mol of the epoxy group of the epoxy resin (a). By reacting in the range of 1.05 mol, the phosphorus-containing epoxy resin of the present invention can be obtained. By setting it as this molar ratio range, the molar ratio of the phenolic hydroxyl group with respect to 1 mol of epoxy groups of the phosphorus containing epoxy resin obtained can be made into the range of 0.95-1.05 mol.

  And it is preferable not to make it react completely so that a part of active hydrogen group and an epoxy group may remain so that the said equivalent range may be satisfied, and to set reaction rate to 70 to 92%. In addition, either the active hydrogen group or the epoxy group is completely reacted, and the remaining active hydrogen group or epoxy group is reacted with a polyfunctional epoxy compound or active hydrogen group-containing compound to give the lost functional group. You can also In particular, this method is preferred when the epoxy resin (a) or the phosphorus compound (b) having an active hydrogen group consists of only a monofunctional group.

  The phosphorus-containing epoxy resin thus obtained has excellent solvent solubility, can be easily dissolved even in a solvent that could not be dissolved by the phosphorus-containing polyhydroxy polyether resin, and the solution viscosity is low, so that the glass cloth can be impregnated. Easy.

  The phosphorus-containing epoxy resin composition of the present invention includes an epoxy resin (D) and a curing agent (C), and the epoxy resin (D) includes the phosphorus-containing epoxy resin (A) of the present invention and other epoxy resins. (B) is included.

  As the epoxy resin (B) used in the phosphorus-containing epoxy resin composition, the same epoxy resin (a) as that described above can be used. The epoxy resin (B) may contain phosphorus atoms in the molecule.

  As the curing agent (C) used in the phosphorus-containing epoxy resin composition, the same one as the reactive compound (c3) can be used.

  The epoxy resin (D) and the curing agent (C) can be blended under the conditions for preparing a normal epoxy resin composition, and the curing agent (C) is usually active against 1 equivalent of epoxy group of the epoxy resin (B). It mix | blends so that a hydrogen group may be 0.2-1.5 equivalent. For example, when a phenolic or amine curing agent is used, an active hydrogen group is included in an equivalent amount with respect to the epoxy group, and when an acid anhydride curing agent is used, an acid anhydride with respect to 1 equivalent of the epoxy group. The group is blended in an amount of 0.5 to 1.5 equivalents, preferably 0.6 to 1.0 equivalents. When dicyandiamide (DICY) is used, 0.2 to 1.2 equivalents, preferably 0.3 to 1.1 equivalents, of active hydrogen groups are used per 1 equivalent of epoxy group. When the reaction proceeds by contact like imidazole compounds, they may be blended at a predetermined mass ratio with respect to the epoxy resin.

  The phosphorus containing epoxy resin composition of this invention can be obtained by mix | blending the phosphorus containing epoxy resin (A) of this invention with what mix | blended the epoxy resin and the hardening | curing agent (C). The compounding amount of the phosphorus-containing epoxy resin only needs to be increased or decreased depending on the desired phosphorus content in the composition, and a curing reaction with the epoxy resin or the curing agent resulting from the compounding of the phosphorus-containing epoxy resin is possible. Since this reaction occurs, the cured product becomes more uniform and high properties such as heat resistance and adhesiveness can be obtained. The compounding quantity of the phosphorus containing epoxy resin (A) of this invention is 0.5-99 with respect to the sum total of the phosphorus containing epoxy resin (A) of this invention, the other epoxy resin (B), and a hardening | curing agent (C). 0.5 mass%, preferably 5-90 mass%, more preferably 15-75 mass%, and even more preferably 30-60 mass%.

In addition, the phosphorus-containing epoxy resin composition of the present invention includes a filler, a thermosetting resin, a thermoplastic resin, a silane coupling agent, an antioxidant, a release agent, an antifoaming agent, an emulsifier, as necessary. Various additives such as thixotropic agents, smoothing agents, flame retardants, and pigments can be blended.
As fillers, fused silica, crystalline silica, alumina, silicon nitride, aluminum hydroxide, talc, calcined talc, clay, kaolin, boehmite, mica, calcium carbonate, calcium silicate, calcium hydroxide, magnesium hydroxide, magnesium carbonate , Barium carbonate, barium sulfate, boron nitride, titanium oxide, glass powder, silica balloon, carbon, carbon fiber, glass fiber, alumina fiber, silica alumina fiber, silicon carbide fiber, polyester fiber, cellulose fiber, aramid fiber, synthetic fiber, A ceramic fiber etc. are mentioned.
Examples of the thermosetting resin include an epoxy resin, a melanin resin, an isocyanate resin, a phenol resin, a polyester resin, a cyanate resin, an imide resin, and a vinyl resin.
Thermoplastic resins include polyphenyl ether, polyhydroxy polyether resin, acrylic resin, petroleum resin, indene resin, polyurethane, polyester, polyamide, polyimide, polyamideimide, polyetherimide, polyethersulfone, polysulfone, polyetheretherketone, Examples thereof include polyphenylene sulfide and polyvinyl formal, coumarone indene resin, fine particle rubber, and thermoplastic elastomer.

  The phosphorus-containing epoxy resin composition of the present invention is particularly useful for circuit board applications, and a prepreg can also be obtained by impregnating and drying a sheet-like base material. As the sheet-like substrate, inorganic fibers such as glass, or woven or non-woven fabrics of organic fibers such as polyester, polyamine, polyacryl, polyimide, Kevlar, etc. can be used, but it is not limited thereto. The method for producing the prepreg is not particularly limited. For example, after impregnating a sheet-like substrate by dipping and impregnating a phosphorus-containing epoxy resin composition in a resin varnish whose viscosity is adjusted with a solvent, the resin component is dried by heating. Can be semi-cured (B-stage), and can be dried by heating at 100 to 200 ° C. for 1 to 40 minutes, for example. Moreover, it is preferable that the resin amount in a prepreg shall be 30-80 mass% of resin parts.

  The phosphorus-containing epoxy resin composition of the present invention can be molded and cured by the same method as known epoxy resin compositions to obtain a cured product. The molding method and the curing method can be the same methods as known epoxy resin compositions, and the method unique to the resin composition of the present invention is unnecessary. The cured phosphorus-containing epoxy resin of the present invention can take the form of a laminate, a molded product, an adhesive, a coating film, a film, etc., has good flame retardancy, heat resistance, and adhesiveness, and is an electric / electronic component. It was found to be useful as a material such as a sealing material, a copper-clad laminate, an insulating paint, a flame retardant paint, a composite material, and an insulating flame retardant adhesive.

  Examples of the present invention are shown below, but the scope of the present invention is not limited to these examples. Unless otherwise specified, parts represent parts by mass, and% represents mass%. The analysis method and measurement method are as follows.

Nonvolatile content: JIS K 7235-1986
Varnish viscosity: A cone plate viscometer (manufactured by Tokyo Keiki Co., Ltd.) was used, and the rotor was measured using a standard cone (1 ° 34 ') in an environment of 25 ° C at a rotation speed of 10 rpm.

Epoxy equivalent: Conforms to JIS K 7236.
・ Hydroxyl equivalent: THF containing 4% methanol was added to the sample, 10% tetrabutylammonium hydroxide was added, and the absorbance between 400 nm and 250 nm was measured using an ultraviolet-visible spectrophotometer. It calculated | required as g number of the samples per hydroxyl group equivalent.

Phosphorus content: Sulfuric acid, hydrochloric acid and perchloric acid were added to the sample and heated to wet ash to convert all phosphorus atoms to orthophosphoric acid. Metavanadate and molybdate were reacted in a sulfuric acid acidic solution, and the absorbance at 420 nm of the resulting phosphomadomolybdate complex was measured, and the phosphorus atom content was expressed in%. The phosphorus content of the laminate was expressed as the content relative to the resin content of the laminate.

-Number average molecular weight (Mn): molecular weight distribution was measured using gel permeation chromatography (GPC) (manufactured by Tosoh Corporation, HLC-8220GPC), and converted from a calibration curve obtained from standard polystyrene.

Infrared absorption spectrum: Measured by a tablet method (KBr) using a Fourier transform infrared spectrophotometer.

-State of varnish: The case where the mixture was uniformly mixed to form a uniform solution after blending was indicated by ○, and the case where turbidity and separation occurred was indicated by ×.
Impregnation property: Glass cloth was impregnated at room temperature, and the time required for impregnation was evaluated at three levels. Within 5 minutes; ○, 5-30 minutes: Δ, more than 30 minutes: ×.

Glass transition temperature (Tg): Expressed by the DSC extrapolated temperature when measured with a differential scanning calorimeter at 10 ° C./min.

-Adhesive force: Conforms to JIS C 6481.
Flame retardance: Conforms to UL94 (Underwriters Laboratories Inc. safety certification standard). Evaluation was described by V-0, V-1, and V-2. However, what was completely burned was marked as “burning”.

Example 1
In a four-necked glass separable flask experimental apparatus equipped with a stirrer, a thermometer, a cooling pipe, and a nitrogen gas introduction pipe, 305.4 parts of HCA (manufactured by Sanko Co., Ltd., phosphorus content 14.2%), 219.2 parts of 1,4-naphthoquinone (manufactured by Kawasaki Kasei Kogyo Co., Ltd.) and 650 parts of toluene were added, reacted at 75 ° C. for 30 minutes, heated up, and reacted at 110 ° C. for 90 minutes. DOPO-NQ was obtained by removing toluene. 475.4 parts of Epototo YDF-170 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., bisphenol F type liquid epoxy resin, epoxy equivalent 170 g / eq), 52.6 parts of diethylene glycol dimethyl ether (hereinafter referred to as MDM) as a reaction solvent, catalyst Then, 0.26 part of triphenylphosphine (TPP) was added, reacted at 160 ° C. for 3 hours, and diluted with methyl ethyl ketone (MEK).
In the reaction, the molar ratio of phenolic hydroxyl group to 1 mol of epoxy group was 0.99. The resulting phosphorus-containing epoxy resin solution was dark brown and transparent with a non-volatile content of 65%, a varnish viscosity of 3650 mPa · s, an epoxy equivalent of 1630 g / eq, a hydroxyl group equivalent of 1630 g / eq, a phosphorus content of 4.3%, and a number average molecular weight of 1225. there were. From the results of epoxy equivalent and hydroxyl equivalent, the amount of hydroxyl group relative to 1 mol of epoxy group was 1.00 mol.

Example 2
483.5 parts of Epototo YDF-170 516.5 parts, HCA-HQ (manufactured by Sanko Co., Ltd., melting point 256 ° C., phosphorus content 9.6%, hydroxyl group equivalent 162 g / eq) in the same apparatus as in Example 1. Prepared. To this, 111 parts of 1-methoxy-2-propanol (hereinafter PGM) as a reaction solvent and 0.24 parts of TPP as a catalyst were added, reacted at 150 ° C. for 6 hours, and diluted with MEK.
In the reaction, the molar ratio of phenolic hydroxyl group to 1 mol of epoxy group was 0.98. The obtained phosphorus-containing epoxy resin solution was light yellow and transparent with a nonvolatile content of 65%, a varnish viscosity of 2850 mPa · s, an epoxy equivalent of 2110 g / eq, a hydroxyl group equivalent of 2220 g / eq, a phosphorus content of 4.6%, and a number average molecular weight of 973. there were. From the results of epoxy equivalent and hydroxyl equivalent, the hydroxyl group was 0.95 mole relative to 1 mole of the epoxy group.

Example 3
542 parts of Epototo YD-128 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., bisphenol A type liquid epoxy resin, epoxy equivalent 187 g / eq), PPQ (manufactured by Hokuko Chemical Co., Ltd., phosphorus content 10) %, Hydroxyl equivalent 155 g / eq) was charged in 458 parts. To this, 176 parts of MDM as a reaction solvent and 0.1 part of 2-ethyl-4-methylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., hereinafter 2E4MZ) as a catalyst were added and reacted at 155 ° C. for 5 hours. Diluted.
In the reaction, the molar ratio of the phenolic hydroxyl group to 1 mol of the epoxy group was 1.02. The resulting phosphorus-containing epoxy resin solution was light yellow and transparent, with a nonvolatile content of 60%, a varnish viscosity of 3050 mPa · s, an epoxy equivalent of 4050 g / eq, a hydroxyl group equivalent of 3930 g / eq, a phosphorus content of 4.6%, and a number average molecular weight of 1986. there were. From the results of epoxy equivalent and hydroxyl equivalent, the hydroxyl group was 1.03 mol per 1 mol of the epoxy group.

Example 4
In the same apparatus as in Example 1, 453 parts of Epototo YDF-170, 28 parts of Epototo YDPN-638 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., phenol novolac type epoxy resin, epoxy equivalent 177 g / eq), DOPO-NQ (reagent, 519 parts of a phosphorus content of 8.2% and a hydroxyl group equivalent of 187 g / eq) were charged. To this, 176 parts of PGM as a reaction solvent and 0.26 parts of tris- (2,6-dimethoxyphenyl) phosphine (reagent) as a catalyst were added, reacted at 155 ° C. for 3 hours, and diluted with MEK.
In the reaction, the molar ratio of phenolic hydroxyl group to 1 mol of epoxy group was 0.98. The obtained phosphorus-containing epoxy resin solution was light yellow and transparent, with a nonvolatile content of 65%, a varnish viscosity of 3350 mPa · s, an epoxy equivalent of 2410 g / eq, a hydroxyl group equivalent of 2500 g / eq, a phosphorus content of 4.3%, and a number average molecular weight of 1365. there were. From the results of the epoxy equivalent and the hydroxyl equivalent, the hydroxyl group was 0.96 mole relative to 1 mole of the epoxy group.

Example 5
In the same apparatus as in Example 1, 548 parts of YSLV-80XY (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., tetramethylbisphenol F type epoxy resin, epoxy equivalent 191 g / eq, melting point 79 ° C.) and 452 parts of HCA-HQ were charged. To this, 176 parts of PGM as a reaction solvent and 0.2 part of TPP as a catalyst were added, reacted at 155 ° C. for 6 hours, and diluted with MEK.
In the reaction, the molar ratio of phenolic hydroxyl group to 1 mol of epoxy group was 0.97. The obtained phosphorus-containing epoxy resin solution was light yellow and transparent, with a non-volatile content of 65%, a varnish viscosity of 3600 mPa · s, an epoxy equivalent of 1370 g / eq, a hydroxyl group equivalent of 1390 g / eq, a phosphorus content of 4.3%, and a number average molecular weight of 1022. there were. From the results of epoxy equivalent and hydroxyl equivalent, the amount of hydroxyl group relative to 1 mol of epoxy group was 0.99 mol.

Example 6
In the same apparatus as in Example 1, 540 parts of Epototo YDF-170, 80 parts of Shonor BRG-557 (manufactured by Showa Denko KK, phenol novolac resin, hydroxyl group equivalent 105 g / eq) and 380 parts of HCA-HQ were charged. . To this, 111 parts of PGM as a reaction solvent and 0.24 parts of TPP as a catalyst were added, reacted at 150 ° C. for 4 hours, and diluted with MEK.
In the reaction, the molar ratio of phenolic hydroxyl group to 1 mol of epoxy group was 0.98. The resulting phosphorus-containing epoxy resin solution was light yellow and transparent, with a nonvolatile content of 65%, a varnish viscosity of 4020 mPa · s, an epoxy equivalent of 2950 g / eq, a hydroxyl group equivalent of 2860 g / eq, a phosphorus content of 3.5%, and a number average molecular weight of 1630. there were. From the results of epoxy equivalent and hydroxyl equivalent, the hydroxyl group was 1.03 mol per 1 mol of the epoxy group.

Example 7
In the same apparatus as in Example 1, 504 parts of Epototo YDPN-638 and 401 parts of HCA were charged. To this, 250 parts of MDM as a reaction solvent and 0.2 part of TPP as a catalyst were added and reacted at 150 ° C. for 4 hours. After cooling to 100 ° C., 95 parts of trimellitic anhydride was added, reacted at 100 ° C. for 2 hours, and diluted with MEK.
The obtained phosphorus-containing epoxy resin solution was light yellow and transparent, non-volatile content 65%, varnish viscosity 6750 mPa · s, epoxy equivalent 1029 g / eq, active hydrogen equivalent (acid equivalent) 1011 g / eq, phosphorus content 5.7%, The number average molecular weight was 851. From the results of the epoxy equivalent and the active hydrogen equivalent (acid equivalent), the active hydrogen equivalent (acid equivalent) per 1 mol of the epoxy group was 1.02 mol. In addition, the active hydrogen equivalent (acid equivalent) was measured based on JIS K 0070 standard, and the acid equivalent was calculated | required from the obtained acid value. Specifically, measurement was performed using a potentiometric titrator, cyclohexanone as a solvent, and a 0.1 N KOH methanol solution.

Reference example 1
In the same apparatus as in Example 1, 687 parts of Epototo YDF-170 and 314 parts of HCA-HQ were charged. To this, 110 parts of PGM as a reaction solvent and 0.06 part of TPP as a catalyst were added and reacted at 165 ° C. for 4 hours, and then diluted with MEK.
In the reaction, the molar ratio of phenolic hydroxyl group to 1 mol of epoxy group was 0.48. The obtained phosphorus-containing epoxy resin solution was light yellow and transparent, with a nonvolatile content of 70%, a varnish viscosity of 510 mPa · s, an epoxy equivalent of 301 g / eq, a hydroxyl group equivalent of 850 g / eq, a phosphorus content of 3.0%, and a number average molecular weight of 587. there were. From the results of epoxy equivalent and hydroxyl equivalent, the hydroxyl group was 0.35 mol relative to 1 mol of the epoxy group.

Reference example 2
In the same apparatus as Example 1, 480.7 parts of HCA-HQ, 519.3 parts of Epototo YD-8125 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., bisphenol A type liquid epoxy resin, epoxy equivalent 172 g / eq), cyclohexanone And 2E4MZ as a catalyst were added in an amount of 0.1 part and reacted at a temperature of 155 ° C to 170 ° C for 15 hours, and then diluted by adding 930 parts of cyclohexanone and 930 parts of N, N-dimethylformamide.
In the reaction, the molar ratio of phenolic hydroxyl group to 1 mol of epoxy group was 0.98. The obtained phosphorus-containing epoxy resin was light yellow and transparent, and had a nonvolatile content of 36%, a varnish viscosity of 5900 mPa · s, an epoxy equivalent of 17200 g / eq, a hydroxyl group equivalent of 18300, a phosphorus content of 4.6%, and a number average molecular weight of 5960. From the results of the epoxy equivalent and the hydroxyl equivalent, the hydroxyl group was 0.94 mole relative to 1 mole of the epoxy group. In addition, since the epoxy equivalent and the hydroxyl equivalent were not dissolved in the designated solvent, they were measured by dissolving in cyclohexanone. The number average molecular weight was determined by conversion of standard polyethylene oxide using N, N-dimethylformamide (containing 20 mM lithium bromide) as an eluent by the GPC method.

The compounds used in the epoxy resin compositions of Examples and Comparative Examples are as follows.
Phosphorus-containing epoxy resin (A)
A1: Epoxy resin obtained in Example 1 A2: Epoxy resin obtained in Example 2 A3: Epoxy resin obtained in Example 3 A4: Epoxy resin obtained in Reference Example 1 A5: Reference Example 2 Epoxy resin and other epoxy resin obtained in (B)
B1: Epototo YDCN-700-7 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., ortho-cresol novolac type epoxy resin, epoxy equivalent 202 g / eq)
B2: Epototo YD-903 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., bisphenol A type solid epoxy resin, epoxy equivalent 812 g / eq)
Curing agent (C)
・ C1: Shonorol BRG-557
C2: DICY (reagent, dicyandiamide, active hydrogen equivalent = 21 g / eq)
Others / Curing accelerator: 2E4MZ
Flame retardant: PX-200 (Daihachi Chemical Industry Co., Ltd., aromatic condensed phosphate ester, phosphorus content 9%)

Examples 8-12 and Comparative Examples 1-5
Each compound was mix | blended with the prescription shown in Table 1 and Table 2, and the epoxy resin composition was obtained.
The obtained epoxy resin varnish was impregnated into a glass cloth (Nittobo Co., Ltd., IPC standard 2116) and dried in a hot air circulating oven at 150 ° C. for 10 minutes to obtain a prepreg.
Furthermore, 4 sheets of the obtained prepreg and copper foil (3EC-III, manufactured by Mitsui Mining & Smelting Co., Ltd., thickness 35 μm) are stacked, and a 2 MPa vacuum press is performed under a temperature condition of 130 ° C. × 15 minutes + 190 ° C. × 70 minutes, A 0.5 mm thick laminate was obtained.
Table 1 shows the results of evaluation of the laminates of the examples, and Table 2 shows the results of evaluation of the laminates of the comparative examples.
In Comparative Example 5 in Table 2, the impregnation property was poor and a prepreg could not be made, so no laminate was prepared.

Claims (9)

  In the phosphorus-containing epoxy resin having an epoxy group and an active hydrogen group, the epoxy equivalent is in the range of 1000 to 5000 g / eq, the active hydrogen equivalent is in the range of 1000 to 5000 g / eq, and 1 equivalent of the epoxy group A phosphorus-containing epoxy resin characterized in that the active hydrogen group is in the range of 0.95 to 1.05 equivalents.   The phosphorus-containing compound according to claim 1, which is obtained by reacting an epoxy resin (a) with an active hydrogen group-containing compound (c) containing a phosphorus compound (b) having an active hydrogen group as an essential component. Epoxy resin. The phosphorus compound according to claim 2, wherein the phosphorus compound (b) having an active hydrogen group includes a phosphorus compound (b1) represented by the general formula (1), a phosphorus compound (b2) represented by the general formula (2), or both. Contains epoxy resin.

(Here, R ₁ , R ₂ , R ₃ and R ₄ represent a hydrocarbon group having 1 to 6 carbon atoms and may be the same or different, and R ₁ and R ₂ , or R ₃ and R 4 ₄ may form a cyclic structure with a phosphorus atom, j and k each represents 0 or 1. A represents an aromatic hydrocarbon group having 6 to 20 carbon atoms.   The total active hydrogen group of the compound (c) having an active hydrogen group including the phosphorus compound (b) is in the range of 0.95 to 1.05 equivalents relative to 1 equivalent of the epoxy group of the epoxy resin (a). The phosphorus-containing epoxy resin according to 2 or 3.   The phosphorus-containing epoxy resin according to any one of claims 1 to 4, wherein the active hydrogen group is a phenolic hydroxyl group.   A phosphorus-containing epoxy resin comprising a phosphorus-containing epoxy resin according to any one of claims 1 to 5 as a part of the epoxy resin in a phosphorus-containing epoxy resin composition comprising an epoxy resin and a curing agent. Composition.   A prepreg obtained by impregnating a fibrous base material with the phosphorus-containing epoxy resin composition according to claim 6.   A cured product obtained by curing the phosphorus-containing epoxy resin composition according to claim 6.   A cured product obtained by curing the prepreg according to claim 7.

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