Flame retardant resin composition containing phosphorus-containing (METH)acryloyl compound, cured product, and laminated plate for electronic circuit board

Abstract

To provide a phosphorus-containing (meth)acryloyl compound which is useful as a reactive type phosphorus-based flame retardant, and is excellent in heat resistance and dielectric characteristics in a cured product, a flame retardant resin composition, a cured product, and a laminated plate for an electronic circuit board.SOLUTION: A resin composition contains one or more phosphorus-containing (meth)acryloyl compounds (A) represented by the following formula (1), a radical polymerizable compound (B) having at least one group represented by the following formula (5), and an azo compound (C), wherein the weight ratio of the compound (A) to the total of the compounds (A) and (B) is 0.6 or less, and the content of the compound (C) with respect to 100 pts.wt. of the total of the compounds (A) and (B) 0.01 to 10 pts.wt.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a reactive phosphorus compound, particularly a phosphorus-containing (meth)acryloyl compound, which is suitably used as a reactive flame retardant for plastic materials. [Background technology]

[0002] Plastic materials have excellent mechanical properties and moldability, and are used in a wide range of applications, from building materials to electrical and electronic equipment. However, most plastic materials are flammable, and so flame retardancy is essential for their use in electrical and electronic products, office automation equipment, and communications equipment, among others, to ensure safety against heat generation, ignition, and fire.

[0003] The addition of additive-type flame retardants, such as halogenated flame retardants, inorganic flame retardants, and phosphorus-based flame retardants, has become common flame retardant technology for plastic materials, regardless of the resin type or application. However, halogenated flame retardants, primarily bromine-based, have been identified as a potential source of highly carcinogenic dioxins, and their use is being restricted in response to the recent trend toward reducing environmentally hazardous substances. Furthermore, while inorganic flame retardants, such as magnesium hydroxide and aluminum hydroxide, have a flame retardant effect due to their endothermic properties, they must be added in large quantities to achieve sufficient flame retardancy, which can cause a deterioration in various properties of plastic molded products. For this reason, phosphorus-based flame retardants are widely used, as they do not produce harmful substances and can provide flame retardancy with the addition of relatively small amounts. However, these additives still inevitably affect properties, such as reducing processability due to bleed-out and lowering the glass transition temperature.

[0004] To address these issues with additive-type flame retardants, reactive flame retardants containing phosphorus atoms (a flame-retardant component) and reactive groups have been developed and widely used. Examples of reactive flame retardants applicable to epoxy resin compositions commonly used in the electronics and electrical fields include Patent Document 1, which discloses a phenolic resin obtained by reacting bisphenol A with formaldehyde to obtain hydroxymethylbisphenol A, followed by reaction with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), as a curing agent for epoxy resins. Patent Document 2 discloses a phosphorus-containing epoxy resin obtained by reacting DOPO with quinones, followed by reaction with an epoxy resin. These resins address processability issues such as flame retardant bleed-out, and do not exhibit deterioration in thermal properties such as heat resistance. Thus, compared to additive-type flame retardants, reactive flame retardants can generally compensate for the drawbacks of additive-type flame retardants, leading to the development of many flame-retardant epoxy resins.

[0005] However, in recent years, in the electronic and electrical materials field, where flame retardancy is essential, the rapid evolution of electronic devices, such as smartphones, has led to increasingly sophisticated requirements for resin components containing flame retardants. In particular, in the information and communications field, the increasing volume of information processed has led to increasingly higher signal frequencies. To reduce transmission loss, resin components used in this field are strongly required to have low dielectric constants and low dielectric dissipation factors. Therefore, in the electronic and electrical materials field, such as circuit boards, radically polymerizable resins, which can achieve lower dielectric constants and lower dielectric dissipation factors, have become widely used in place of epoxy resins. Therefore, in addition to flame retardants whose reactive groups are reactive with epoxy groups and epoxy resins, there is a demand for halogen-free flame retardants with low dielectric constants and low dielectric dissipation factors that can react with radically polymerizable resins.

[0006] As halogen-free flame retardants having a radically polymerizable functional group, methacryloyl compounds using DOPO are disclosed in Patent Documents 3 and 4. However, there is room for improvement in the dielectric loss tangent.

[0007] As a method for reducing the dielectric loss tangent, Patent Document 5 discloses a method using an azo compound as an initiator. However, when an azo compound is used, the heat resistance of the cured product decreases compared to when an organic peroxide is used as an initiator, depending on the type of resin. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2013-166938 [Patent Document 2] JP 11-279258 [Patent Document 3] WO2023 / 167148 [Patent Document 4] WO2023 / 167019 [Patent Document 5] WO2019 / 208471 Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, the problem to be solved by the present invention is to provide a phosphorus-containing (meth)acryloyl compound, a flame-retardant resin composition, a cured product, and a laminate for electronic circuit boards, which are useful as reactive phosphorus-based flame retardants and have excellent heat resistance and dielectric properties in the cured product. [Means for solving the problem]

[0010] As a result of intensive research into the above-mentioned problems, the present inventors have found that a cured product obtained by using an azo compound as an initiator and curing a composition containing a phosphorus-containing (meth)acryloyl compound having a specific structure has excellent flame retardancy, heat resistance, and dielectric properties, and have arrived at the present invention.

[0011] Specifically, the present invention relates to a resin composition comprising one or more phosphorus-containing (meth)acryloyl compounds (A) represented by the following formula (1) or (4), a radically polymerizable compound (B) having at least one group represented by the following formula (5), and an azo compound (C), wherein the weight ratio of compound (A) to the total of compounds (A) and (B) is 0.6 or less, and the content of compound (C) is 0.01 to 10 parts by weight per 100 parts by weight of the total of compounds (A) and (B), and further to a laminate for electronic circuit boards containing the resin composition as an essential component. [ka] (In formula (1), R1 and R2 are hydrogen, a hydroxyl group, or a group represented by -OR or -R, and R is a C2 to C40 hydrocarbon group. R1 and R2 may be the same or different, and R1 and R2 may form a cyclic structure together with the phosphorus atom. X represents a trivalent C6 to C20 aromatic hydrocarbon group, and Y1 and Y2 are substituents represented by the following formula (2) or (3).) [ka] (In formula (2), R3 is hydrogen or a methyl group.) [ka] (In formula (3), R4 is hydrogen or a methyl group, and R5 is a C1 to C20 hydrocarbon group.) [ka] (In formula (4), R6 and R7 are hydrogen, a hydroxyl group, or a group represented by -OR or -R, and R is a C2 to C40 hydrocarbon group. R6 and R7 may be the same or different, and R6 and R7 may form a cyclic structure together with the phosphorus atom. R8 is a C1 to C20 hydrocarbon group. Y is a substituent represented by formula (2).) [ka] (In formula (5), n represents 0 to 10, Z represents an arylene group, and R9 to R11 each independently represent a hydrogen atom or an alkyl group.) [Effects of the Invention]

[0012] The cured product obtained by curing the resin composition of the present invention exhibits a low dielectric constant and dielectric loss tangent and exhibits little deterioration in heat resistance, making the resin composition and cured product suitable for high-frequency substrates. DETAILED DESCRIPTION OF THE INVENTION

[0013] In the description of the present invention, with regard to the names of acrylic resins, acrylic compounds, acrylate compounds, etc., in accordance with common practice, for example, both "acryloyl" and "methacryloyl" may be collectively referred to as "(meth)acryloyl," both "acrylic" and "methacrylic" may be collectively referred to as "(meth)acrylic," and both "acrylate" and "methacrylate" may be collectively referred to as "(meth)acrylate." The phosphorus-containing (meth)acryloyl compound includes not only a single compound but also a mixture (resin).

[0014] The present invention relates to a resin composition and a cured product obtained by blending a phosphorus-containing (meth)acryloyl compound (A), a radically polymerizable compound (B), and an azo compound (C). Each component will be described below.

[0015] The resin composition of the present invention contains, as an essential component, one or more phosphorus-containing (meth)acryloyl compounds (A) represented by the following formula (1) or (4): First, the phosphorus-containing (meth)acryloyl compound (A) represented by formula (1) will be explained. [ka] In formula (1), R1 and R2 are hydrogen, a hydroxyl group, a group represented by -OR or -R, and R is a C2 to C40 hydrocarbon group. R1 and R2 may be the same or different, and R1 and R2 may form a cyclic structure together with the phosphorus atom. Preferably, R is a phenyl group, and the aromatic ring of the phenyl group may have a C1 to C3 alkyl group.

[0016] In formula (1), X is a trivalent C6 to C20 aromatic hydrocarbon group. Examples of the aromatic hydrocarbon group include a benzene ring group, a naphthalene ring group, a biphenyl ring group, and a terphenyl ring group. The aromatic hydrocarbon group may be unsubstituted or may have a substituent such as a C1 to C6 alkyl group, a C1 to C6 alkoxy group, a C6 to C10 aryl group, a C6 to C10 aryloxy group, a C7 to C12 aralkyl group, or a C7 to C12 aralkyloxy group. X is preferably a benzene ring group, a naphthalene ring group, or an aromatic substituent in which a methyl group or a 1-phenylethyl group is substituted on one of these.

[0017] In formula (1), Y1 and Y2 are substituents represented by the following formula (2) or (3). [ka] In formula (2), R3 is hydrogen or a methyl group. [ka] In formula (3), R4 is hydrogen or a methyl group, and R5 is a C1 to C20 hydrocarbon group. Examples of the C1 to C20 hydrocarbon group include a linear or branched aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or a C6 to C20 aromatic hydrocarbon group. Examples of the aliphatic hydrocarbon group include a C1 to C20 alkyl group, and examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, a biphenyl group, and an anthranyl group. When R5 contains an aromatic hydrocarbon group, the aromatic ring may have a substituent. Examples of the substituent include a carboxy group, an aliphatic hydrocarbon group, an acyl group, an alkoxy group, a cyano group, a hydroxyl group, a methacryloyloxy group, a vinylbenzyl ether group, and groups formed by linking these substituents. When the aromatic hydrocarbon group has a substituent, the number of carbon atoms (C) does not include the number of carbon atoms of the substituent.

[0018] Next, the phosphorus-containing (meth)acryloyl compound (A) represented by formula (4) will be described. [ka] In formula (4), R6 and R7 are hydrogen, a hydroxyl group, a group represented by -OR or -R, and R is a C2 to C40 hydrocarbon group. R6 and R7 may be the same or different, and R6 and R7 may form a cyclic structure together with the phosphorus atom.

[0019] In formula (4), R8 is a C1 to C20 hydrocarbon group. Examples of the C1 to C20 hydrocarbon group include aliphatic hydrocarbon groups having a linear or branched structure, alicyclic hydrocarbon groups, and C6 to C20 aromatic hydrocarbon groups. Examples of the aliphatic hydrocarbon group include C1 to C20 alkyl groups, and examples of the aromatic hydrocarbon group include phenyl groups, naphthyl groups, biphenyl groups, and anthranyl groups. When R8 contains an aromatic hydrocarbon group, the aromatic ring may have a substituent. Examples of the substituent include a carboxy group, an aliphatic hydrocarbon group, an acyl group, an alkoxy group, a cyano group, a hydroxyl group, a methacryloyloxy group, a vinylbenzyl ether group, and groups formed by linking these substituents. When the aromatic hydrocarbon group has a substituent, the number of carbon atoms of the substituent is not included in the number of carbon atoms (C) above. In formula (4), Y is a substituent represented by formula (2).

[0020] The resin composition of the present invention may contain at least one of the phosphorus-containing (meth)acryloyl compounds (A) represented by formula (1) or (4) as an essential component. Therefore, the resin composition may contain either the compound of formula (1) or the compound of formula (4) alone, or a mixture of both compounds. Preferably, the compound of formula (1) and the compound of formula (4) are mixed together, in which case the compound of formula (1) accounts for preferably 50 to 95 mol %, more preferably 70 mol % or more, and even more preferably 80 mol % or more.

[0021] The radically polymerizable compound (B) is a compound having at least one group represented by the following formula (5). [ka] In the formula (5), n represents 0 to 10, Z represents an arylene group, and R9 to R11 each independently represent a hydrogen atom or an alkyl group.

[0022] The arylene group in formula (5) is not particularly limited. Examples of the arylene group include monocyclic aromatic groups such as phenylene groups, and polycyclic aromatic groups in which the aromatic ring is not monocyclic but polycyclic aromatic such as naphthalene rings. The arylene group also includes derivatives in which the hydrogen atom bonded to the aromatic ring is substituted with a functional group such as an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group. The alkyl groups represented by R9 to R11 in formula (5) are not particularly limited, and are preferably C1 to C18 alkyl groups, more preferably C1 to C10 alkyl groups. Specific examples include methyl, ethyl, propyl, hexyl, and decyl groups.

[0023] The radical polymerizable compound (B) is not particularly limited as long as it has at least one group represented by formula (5) in the molecule. In formula (5), when n is 0, this indicates that the arylene group Z is directly bonded to the terminal or molecular chain of compound (B).

[0024] Examples of the radical polymerizable compound (B) include a modified polyphenylene ether compound having a group represented by formula (5) at the molecular end, and a polymer having a structural unit represented by the following formula (9) in the molecule. [ka] In formula (9), Z represents an arylene group. R9 to R11 each independently represent a hydrogen atom or an alkyl group and may be the same or different. R22 to R24 each independently represent a hydrogen atom or a C1 to C6 alkyl group and may be the same or different.

[0025] The radical polymerizable compound (B) may have a group represented by formula (5) as described above, and the atom to which this group is bonded is not particularly limited and may be, for example, an oxygen atom or a carbon atom. Specifically, in the case of a modified polyphenylene ether compound, the atom to which the group represented by formula (5) is bonded may be, for example, an oxygen atom at the end of the main chain. In addition, in the case of a polymer having a structural unit represented by formula (9) in the molecule, the atom to which the group represented by formula (5) is bonded may be, for example, a carbon atom constituting the main chain, as represented by formula (9). In addition, as compound (B), these may be used alone or in combination.

[0026] The modified polyphenylene ether compound is not particularly limited as long as it is a modified polyphenylene ether compound having a group represented by formula (5) at the molecular terminal. Among them, the structure of terminal polyphenylene ether (E) defined by the following formula (6) is preferred. [ka] In formula (6), the sum of m and n is 1 to 30. W represents a substituent having a carbon-carbon unsaturated double bond. R14 to R21 represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group, and may be the same group or different groups. Among these, R14 to R21 are preferably a hydrogen atom or an alkyl group.

[0027] Specific examples of the radical polymerizable compound (C) include a resin compound that is a copolymer of a monovinyl compound and a divinyl compound, and the copolymer contains a plurality of structural units derived from a divinyl aromatic compound. Specific examples include the compounds described in Japanese Patent No. 7126493.

[0028] In the resin composition of the present invention, it is necessary to use an azo compound (C) as the radical polymerization initiator, instead of a peroxide. The azo compound (C) is not particularly limited as long as it is a compound having an azo group in the molecule, but a structure represented by the following formula (7) is particularly preferred. [ka] In formula (7), R12 and R13 each independently represent a hydrogen atom or an alkyl group. The alkyl group in R12 and R13 may be a linear alkyl group or a branched alkyl group, and the alkyl group is preferably a C1 to C8 alkyl group.

[0029] The linear alkyl group may be any group as long as it is linear, and is preferably a C1 to C8 group, more preferably a C4 to C8 group. Specific examples of the linear alkyl group include a butyl group, a pentyl group, a hexyl group, and an octyl group. The branched alkyl group may be any group as long as it is branched, and is preferably a group of C3 to C8, and more preferably a group of C4 to C8. Specific examples of the branched alkyl group include a t-butyl group and a 2,2',4,4'-tetramethylbutyl group.

[0030] The azo compound (C) may be used alone or in combination of two or more. Preferred specific examples of the azo compound (C) include compounds represented by the following formula (8): [ka]

[0031] In the resin composition of the present invention, the amount of the phosphorus-containing (meth)acryloyl compound (A) blended is such that the weight ratio of (A) to the total of the compounds (A) and (B) is 0.6 or less. When the amount of the phosphorus-containing (meth)acryloyl compound (A) is within the above range, even when the azo compound (C) is used as an initiator, the dielectric loss tangent can be reduced while maintaining the same heat resistance as when an organic peroxide is used as an initiator. The weight ratio of the compound (A) is preferably 0.5 or less, more preferably 0.4 or less.

[0032] The amount of the azo compound (C) to be added is 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, and more preferably 0.5 to 3.0 parts by weight, relative to 100 parts by weight of the resin component.

[0033] The resin composition of the present invention may contain a curable resin or a thermoplastic resin. The blending ratio of the curable resin or thermoplastic resin is not particularly limited, but it is advisable to blend, for example, in the range of 10 to 300 parts by weight per 100 parts by weight of the total of the compounds (A) and (B).

[0034] Examples of the curable resin include unsaturated polyester resin, curable maleimide resin, epoxy resin, polycyanate resin, phenol resin, and one or more vinyl compounds having one or more polymerizable unsaturated hydrocarbon groups in the molecule. Preferred are epoxy resin and one or more vinyl compounds having one or more polymerizable unsaturated hydrocarbon groups in the molecule.

[0035] When the curable resin is an epoxy resin, it is preferably one or more epoxy resins selected from epoxy resins having two or more epoxy groups per molecule. Examples of such epoxy resins include cresol novolac epoxy resins, triphenylmethane epoxy resins, biphenyl epoxy resins, naphthalene epoxy resins, bisphenol A epoxy resins, and bisphenol F epoxy resins. These may be used alone or in combination of two or more. It is believed that the use of such epoxy resins minimizes the impact on the excellent dielectric properties and fluidity of the curable resin composition of the present invention, while adequately enhancing the heat resistance and adhesion of the cured product.

[0036] Furthermore, when an epoxy resin is contained, a curing agent may be used in addition to the epoxy resin. The curing agent is not particularly limited, and examples thereof include phenol-based curing agents, amine-based compounds, amide-based compounds, acid anhydride-based compounds, naphthol-based curing agents, active ester-based curing agents, benzoxazine-based curing agents, and cyanate ester-based curing agents. These may be used alone or in combination of two or more.

[0037] Furthermore, when an epoxy resin is blended, a curing accelerator can be used as needed. Examples include amines, imidazoles, organic phosphines, Lewis acids, etc. The amount added is usually in the range of 0.2 to 5 parts by weight per 100 parts by weight of the epoxy resin.

[0038] When the curable resin is one or more vinyl compounds having one or more polymerizable unsaturated hydrocarbon groups in the molecule, the type thereof is not particularly limited. That is, the vinyl compounds may be any compounds that can be crosslinked and cured by reacting with the phosphorus-containing (meth)acryloyl compound of the present invention. The polymerizable unsaturated hydrocarbon group is preferably a carbon-carbon unsaturated double bond, and more preferably a compound having two or more carbon-carbon unsaturated double bonds in the molecule.

[0039] The average number of carbon-carbon unsaturated double bonds per molecule of vinyl compounds as curable resins varies depending on the Mw of the vinyl compounds, but is preferably 1 to 20, and more preferably 2 to 18. If the number of terminal double bonds is too small, it tends to be difficult to obtain sufficient heat resistance of the cured product. On the other hand, if the number of terminal double bonds is too large, the reactivity becomes too high, which may cause problems such as reduced storage stability of the curable resin composition or reduced fluidity of the curable resin composition.

[0040] Examples of vinyl compounds include trialkenyl isocyanurate compounds such as triallyl isocyanurate (TAIC), polyfunctional (meth)acrylate compounds having two or more (meth)acryloyl groups in the molecule, vinyl compounds (polyfunctional vinyl compounds) having two or more vinyl groups in the molecule such as polybutadiene, and vinylbenzyl compounds such as styrene and divinylbenzene. Among these, compounds having two or more carbon-carbon double bonds in the molecule are preferred, specifically TAIC, polyfunctional (meth)acrylate compounds, polyfunctional vinyl compounds, and divinylbenzene compounds. The use of these compounds is believed to more favorably form crosslinks during the curing reaction, thereby further improving the heat resistance of the cured product of the curable resin composition. These compounds may be used alone or in combination. Compounds having one carbon-carbon unsaturated double bond in the molecule may also be used in combination. Examples of compounds having one carbon-carbon unsaturated double bond in the molecule include compounds having one vinyl group in the molecule (monovinyl compounds).

[0041] Examples of thermoplastic resins include polystyrene, polyphenylene ether resin, polyetherimide resin, polyethersulfone resin, PPS resin, polycyclopentadiene resin, polycycloolefin resin, etc., known thermoplastic elastomers (e.g., styrene-ethylene-propylene copolymer, styrene-ethylene-butylene copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, hydrogenated styrene-butadiene copolymer, hydrogenated styrene-isoprene copolymer, etc.), and rubbers (e.g., polybutadiene, polyisoprene). Preferably, unmodified or modified polyphenylene ether resin and hydrogenated styrene-butadiene copolymer are used.

[0042] The flame-retardant resin composition of the present invention can contain a filler. Examples of fillers include those added to enhance heat resistance and flame retardancy, and known fillers can be used, but are not particularly limited thereto. The inclusion of a filler can further enhance heat resistance, dimensional stability, flame retardancy, and other properties. Specific examples include silica such as spherical silica, metal oxides such as alumina, titanium oxide, and mica, metal hydroxides such as aluminum hydroxide and magnesium hydroxide, talc, aluminum borate, barium sulfate, and calcium carbonate. When metal hydroxides such as aluminum hydroxide and magnesium hydroxide are used, they act as flame retardant aids, ensuring flame retardancy even with a low phosphorus content. Among these, silica, mica, and talc are preferred, and spherical silica is more preferred. These may be used alone or in combination.

[0043] The filler may be used as is, or may be surface-treated with a silane coupling agent such as an epoxysilane or aminosilane type. From the viewpoint of reactivity with the radical polymerization initiator, vinylsilane, methacryloxysilane, acryloxysilane, and styrylsilane types of silane coupling agents are preferred as the silane coupling agent. This increases the adhesive strength with the metal foil and the interlayer adhesive strength between resins. Instead of surface-treating the filler in advance, the silane coupling agent may be added by integral blending. The content of the filler is preferably 10 to 200 parts by weight, and more preferably 30 to 150 parts by weight, per 100 parts by weight of the total solid content excluding the filler.

[0044] The flame-retardant resin composition of the present invention may further contain additives other than those described above, such as antifoaming agents such as silicone antifoaming agents and acrylate antifoaming agents, heat stabilizers, antistatic agents, ultraviolet absorbers, dyes and pigments, lubricants, and dispersants such as wetting and dispersing agents.

[0045] The cured product obtained by curing the flame-retardant resin composition of the present invention can be used as a molded product, laminate, cast product, adhesive, coating film, or film. For example, a cured product of a semiconductor encapsulating material is a cast product or molded product, and the cured product for such uses can be obtained by molding the curable resin composition using a cast mold or a transfer molding machine, an injection molding machine, or the like, and then heating it at 80 to 230°C for 0.5 to 10 hours.

[0046] The flame-retardant resin composition of the present invention can also be used as a prepreg. When producing a prepreg, the composition can be prepared in a varnish form to be used as a resin varnish for impregnating a substrate (fibrous substrate) for forming the prepreg or for use as a circuit board material for forming a circuit board. This resin varnish is suitable for circuit boards and can be used as a varnish for circuit board materials. Specific uses of the circuit board material referred to here include printed wiring boards, printed circuit boards, flexible printed wiring boards, build-up wiring boards, etc.

[0047] The organic solvent used in the resin varnish is not particularly limited as long as it does not inhibit the curing reaction. Examples include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate, propyl acetate, and butyl acetate; polar solvents such as dimethylacetamide and dimethylformamide; and aromatic hydrocarbon solvents such as toluene and xylene. These can be used alone or in combination. From the viewpoint of dielectric properties, aromatic hydrocarbons such as benzene, toluene, and xylene are preferred. When preparing a resin varnish, the amount of organic solvent used is preferably 5 to 900 parts by weight, more preferably 10 to 700 parts by weight, and particularly preferably 20 to 500 parts by weight, relative to 100 parts by weight of the curable resin composition of the present invention.

[0048] Known materials are used as substrates for preparing prepregs, including, for example, glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, and paper, which may be used alone or in combination of two or more. If necessary, a coupling agent may be used in these substrates to improve adhesion at the interface between the resin and the substrate. Typical coupling agents include silane coupling agents, titanate coupling agents, aluminum-based coupling agents, and zircoaluminate coupling agents.

[0049] A method for obtaining a prepreg includes impregnating a substrate with a resin varnish and then drying it. Impregnation is performed by dipping, coating, or the like. Impregnation can be repeated multiple times as needed, and in this case, it is also possible to repeat impregnation using multiple solutions with different compositions and concentrations to adjust the final resin composition and resin amount to the desired one. After impregnation, the prepreg can be obtained by heating and drying at 100 to 180°C for 1 to 30 minutes. Here, the resin amount in the prepreg is preferably 30 to 80% by weight.

[0050] The curable resin composition of the present invention can also be used as a laminate. When forming a laminate using prepregs, one or more prepregs are laminated together, with metal foils placed on one or both sides to form a laminate. This laminate is then heated and pressurized to form an integrated laminate. The metal foil can be a single, alloy, or composite metal foil of copper, aluminum, brass, nickel, or the like. The conditions for heating and pressing the laminate can be appropriately adjusted to cure the curable resin composition. However, if the pressure is too low, air bubbles may remain inside the resulting laminate, resulting in reduced electrical properties. Therefore, it is preferable to pressurize the laminate under conditions that satisfy moldability. For example, the temperature can be set to 180 to 250°C, the pressure to 49.0 to 490.3 N / cm2 (5 to 50 kgf / cm2), and the heating and pressing time to 40 to 240 minutes. Furthermore, a multilayer board can be fabricated using the single-layer laminate thus obtained as an inner layer material. In this case, a circuit is first formed on a laminate by an additive method, subtractive method, or the like, and the surface of the formed circuit is then blackened with an acid solution to obtain an inner layer material. An insulating layer is formed on one or both circuit-forming surfaces of this inner layer material using a resin sheet, resin-coated metal foil, or prepreg, and a conductor layer is formed on the surface of the insulating layer to form a multilayer board.

[0051] The curable composition of the present invention can also be used for a build-up film. A method for producing a build-up film from the resin composition of the present invention includes, for example, applying a resin varnish to a support film and drying it to form a film-like insulating layer. The film-like insulating layer thus formed can be used as a build-up film for a multilayer printed wiring board. [Example]

[0052] The present invention will now be described with reference to examples, but is not limited to these examples. In each example, all parts are by weight. The physical properties in the synthesis examples and examples were measured by the methods shown below. (1) Phosphorus content: Sulfuric acid, hydrochloric acid, and perchloric acid were added to the sample, which was then heated and wet ashed to convert all phosphorus atoms into orthophosphate. Metavanadate and molybdate were reacted in the sulfuric acid acid solution, and the absorbance of the resulting phosphorus vanadate molybdate complex was measured at 420 nm. The phosphorus atom content was calculated using a calibration curve prepared in advance using potassium dihydrogen phosphate and expressed as a percentage. (2) Glass transition temperature: The resin cured product or molded product was cast into a mold with a shape of 50 mmL x 10 mmW x 2 mmT, and the processed test specimen was measured for loss coefficient (tanδ) using a dynamic viscoelasticity device under conditions of a frequency of 1 Hz and a heating rate of 5°C / min, and the glass transition temperature was calculated from the peak top temperature. (3) Relative permittivity and dielectric loss tangent: The permittivity and dielectric loss tangent at a frequency of 10 GHz were determined by the SPDR method using a material analyzer (manufactured by AGILENT Technologies) in accordance with the IPC-TM-6502.5.5.9 standard. (4) Flame retardancy: Evaluated by the vertical method in accordance with UL94. The ratings were recorded as V-0, V-1, and V-2.

[0053] (Synthesis Example 1) Synthesis of DOPO-NQ A separable glass flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet was charged with 340 parts of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 660 parts of toluene and dissolved at 80°C. 245 parts of 1,4-naphthoquinone was added in portions, taking care to avoid reaction heat generation. The reaction was continued, and the temperature was raised to 110°C for further reaction. After 3 hours, a slurry solution containing dark brown crystals was obtained. The crystals were separated by filtration and dispersed in 500 parts of methanol. This procedure was repeated three times, followed by drying in a hot air circulating oven to obtain a pale yellow powder of the phosphorus-containing phenolic compound 10-(2,5-dihydroxynaphthyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-NQ). [ka]

[0054] (Synthesis Example 2) Synthesis of phosphorus-containing phenol compound A 470 parts of DOPO-NQ, 68 parts of DOPO, 510 parts of toluene as a solvent, phenyl glycidyl ether [ka] 256 parts of the resulting solution were placed in a separable glass flask equipped with a stirrer, thermometer, Dean-Stark apparatus, and nitrogen gas inlet, and dissolved at 110°C. 0.95 parts of triphenylphosphine were added, and the mixture was further heated to 160°C while removing toluene, and the reaction was carried out for 5 hours. The end point of the reaction was confirmed by GPC, and after confirming that the peaks of the raw materials DOPO-NQ, DOPO, and phenyl glycidyl ether had disappeared, the pressure was reduced to 1 kPa using a vacuum pump, and the toluene was distilled off, yielding 800 parts of phosphorus-containing phenol compound A. GPC analysis confirmed that the product contained 43% of a compound in which 2 moles of phenyl glycidyl ether had reacted with 1 mole of DOPO-NQ, 27% of a compound in which 1 mole of phenyl glycidyl ether had reacted with 1 mole of DOPO-NQ, and a total of 26% of a compound in which 1 mole of phenyl glycidyl ether had reacted with 1 mole of DOPO-NQ and DOPO-NQ.

[0055] (Synthesis Example 3) Synthesis of phosphorus-containing methacryloyl compound A In a glass separable flask equipped with a stirrer, a thermometer, a condenser, and a dropping funnel, 100 parts of phosphorus-containing phenol compound A, 100 parts of tetrahydrofuran, 35 parts of triethylamine, and 2.6 parts of 4-dimethylaminopyridine were charged and dissolved at room temperature. [ka] 65 parts of the mixture was added dropwise over 1 hour, and the reaction was continued for a further 6 hours at 50°C, after which it was confirmed by GPC that the peaks of the raw materials had disappeared. The reaction mixture was then concentrated and dissolved in 290 parts of toluene. The mixture was then washed with aqueous sodium carbonate and then with water. After washing with water, the mixture was dehydrated, filtered, and the solvent was further concentrated to adjust the solids concentration to 50%, yielding 240 parts of a toluene solution of phosphorus-containing methacryloyl compound A. The phosphorus content was 4.9%. GPC analysis confirmed that phosphorus-containing methacryloyl compound A contained 43% methacryloyl compounds (compounds belonging to formula (13) = formula (1)) derived from a compound obtained by reacting 2 moles of phenyl glycidyl ether with 1 mole of DOPO-NQ, 29% methacryloyl compounds (compounds belonging to formula (14) = formula (1)) derived from a compound obtained by reacting 1 mole of DOPO-NQ, 19% methacryloyl compounds (compounds belonging to formula (15) = formula (1)) derived from DOPO-NQ, and 7% methacryloyl compounds (compounds belonging to formula (16) = formula (4)) derived from a compound obtained by reacting 1 mole of phenyl glycidyl ether with DOPO. [ka]

[0056] Examples 1 to 3, Comparative Examples 1 to 6 <Preparation of Curable Resin Composition and Preparation of Cured Product> A varnish was prepared by mixing the various components in the proportions shown in Table 1. This varnish was applied to a PET film and dried in an oven at 130°C for 5 minutes to produce a film of the resin composition. This film was then pulverized to obtain a powder of the resin composition. This powder was then sandwiched between stainless steel mirror plates with spacers and molded in a vacuum oven at 210°C for 90 minutes to obtain a cured sample. The glass transition temperature and dielectric properties of this cured sample were evaluated, and the results are shown in Table 1. <Creating a flame retardant test piece> A varnish was prepared by mixing the various components in the proportions shown in Table 1. This resin varnish was then impregnated into glass cloth (manufactured by Nitto Boseki Co., Ltd.; 7628 type; product number H258), which was then dried by heating at 130°C for 5 minutes to obtain a prepreg. Eight sheets of the resulting prepreg were stacked on top and bottom with copper foil (Mitsui Mining & Smelting Co., Ltd., 3EC-III, 35 μm thick), and then vacuum pressed at 2 MPa under temperature conditions of 130°C for 15 minutes and 190°C for 80 minutes to obtain a 1.6 mm thick laminate. The copper foil was etched and cut to obtain flame-retardant test specimens. The flame retardancy of the test specimens was evaluated, and the results are shown in Table 1.

[0057] (Radical polymerizable compound) OPE-2St: Styryl-terminated polyphenylene ether resin manufactured by Mitsubishi Gas Chemical Company, Inc. [ka] (Polymerization initiator) Perbutyl P: 1,3-bis(butylperoxyisopropyl)benzene manufactured by NOF Corporation VR-110: 2,2-azobis(2,4,4-trimethylpentane) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. [ka]

[0058] [Table 1]

Claims

1. A resin composition comprising one or more phosphorus-containing (meth)acryloyl compounds (A) represented by the following formula (1) or (4), a radical polymerizable compound (B) having at least one group represented by the following formula (5), and an azo compound (C), wherein the weight ratio of the compound (A) to the total of the compounds (A) and (B) is 0.6 or less, and the content of the compound (C) is 0.01 to 10 parts by weight per 100 parts by weight of the total of the compounds (A) and (B). 【Chemical 1】 (In formula (1), R1 and R2 are hydrogen, a hydroxyl group, a group represented by -OR or -R, and R is a C2 to C40 hydrocarbon group. R1 and R2 may be the same or different, and R1 and R2 may form a cyclic structure together with the phosphorus atom. X represents a trivalent C6 to C20 aromatic hydrocarbon group, and Y1 and Y2 are substituents represented by the following formula (2) or (3).) 【Chemistry 2】 (In formula (2), R3 is hydrogen or a methyl group.) 【Chemistry 3】 (In formula (3), R4 is hydrogen or a methyl group, and R5 is a C1 to C20 hydrocarbon group.) 【Chemistry 4】 (In formula (4), R6 and R7 are hydrogen, a hydroxyl group, —OR, or a group represented by —R, and R is a C2 to C40 hydrocarbon group. R6 and R7 may be the same or different, and R6 and R7 may form a cyclic structure together with the phosphorus atom. R8 is a C1 to C20 hydrocarbon group. Y is a substituent represented by formula (2).) 【Chemistry 5】 (In formula (5), n represents 0 to 10, Z represents an arylene group, and R9 to R11 each independently represent a hydrogen atom or an alkyl group.)

2. 2. The resin composition according to claim 1, wherein the radical polymerizable compound (B) is a compound represented by the following formula (6): 【Chemistry 6】 (In formula (6), the sum of m and n is 1 to 30. W represents a substituent having a carbon-carbon unsaturated double bond. R14 to R21 represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group, and may be the same group or different groups.)

3. The resin composition according to claim 1, wherein the azo compound (C) is a compound represented by the following formula (7): 【Chemistry 7】 (In formula (7), R12 and R13 each independently represent a hydrogen atom or an alkyl group.)

4. 2. The resin composition according to claim 1, wherein the azo compound (C) is a compound represented by the following formula (8): 【Chemistry 8】

5. A resin composition comprising the resin composition according to claim 1 and at least one curable resin or thermoplastic resin blended therewith.

6. A cured product obtained by curing the resin composition according to claim 1.

7. A laminate for electronic circuit boards, comprising the resin composition according to claim 1 as an essential component.

Images