Gelation inhibitor for maleimides, composition containing the same, and method for inhibiting gelation of maleimides

Abstract

To provide a gelation inhibitor for maleimides, capable of effectively inhibiting the gelation of maleimides.SOLUTION: A gelation inhibitor for maleimides contains a quinone compound A having a condensed polycyclic aromatic skeleton.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a gelation inhibitor for maleimides, a composition containing the same, and a method for inhibiting the gelation of maleimides. [Background technology]

[0002] Maleimides are a group of compounds useful as monomers for heat-resistant resins and intermediates for medicines and agricultural chemicals, and various maleimides have been known so far. When maleimides are used as monomers for heat-resistant resins, they can be used alone, but they can also be used in combination with other curing agents such as diamines, dicyanates, and diallyl compounds to improve toughness and flexibility.

[0003] However, maleimides, particularly bifunctional bismaleimides, often have a high melting point and low solubility, and the melting point and polymerization initiation temperature of such maleimides are relatively close to each other. For this reason, for example, when preparing a composition using maleimides, after the maleimides are heated and melted, there is a risk that the molten maleimides will gel before proceeding to the next step. Such gelation of maleimides is considered to be thermal radical polymerization, and a method for suppressing such gelation and maintaining the molten state of maleimides until polymerization begins has been required. Hereinafter, the induction period from heating a compound such as maleimides to the start of curing may be referred to as "gel time" or "gelation time".

[0004] Here, in order to suppress thermal radical polymerization, it is generally considered effective to add a polymerization inhibitor (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-110160 A [Patent Document 2] JP 2019-183074 A Summary of the Invention [Problem to be solved by the invention]

[0006] For example, Patent Document 1 discloses a technique of using a specific p-benzoquinone derivative as a polymerization inhibitor that inhibits the polymerization of vinyl monomers. For example, in the examples of Patent Document 1, the polymerization induction time of ethoxyethyl methacrylate containing 200 ppm of 1,4-benzoquinone at 135°C is 360 to 490 minutes, which shows an effect of extending the polymerization induction time (12 minutes) when 1,4-benzoquinone is not contained. Patent Document 1 also describes a maleimide compound as a usable vinyl monomer, but there is no description of an example using a maleimide compound, and it is completely unclear to what extent the p-benzoquinone derivative as a polymerization inhibitor has an effect on the maleimide compound (for example, a specific effect of extending the induction time).

[0007] In addition, Patent Document 2 discloses a technique of using a phenolic compound having a specific structure and a naphthoquinone compound as a polymerization inhibitor in combination with a radical curable composition obtained by adding styrene to an unsaturated polyester oligomer as a radical curable composition containing an accelerator and excellent in thermal stability and storage stability. Here, Patent Document 2 discloses that the polymerization inhibitor added to the radical curable composition has three main roles, namely, 1) improving storage stability, 2) improving thermal stability, and 3) ensuring gelation time (gel time), and that it is difficult to prepare a polymerization inhibitor that fulfills all of these roles. The invention described in Patent Document 2 discloses that the above-mentioned two types of polymerization inhibitors are used in combination to improve thermal stability and storage stability, and that a gelation time can be ensured for a certain period of time or more when a curing agent is added and cured. For example, in the examples of Patent Document 2, when a phenolic compound is not used in combination as a polymerization inhibitor, the gel time is reduced from 22 minutes to 4 minutes, and when 1,4-naphthoquinone is not used in combination as a polymerization inhibitor, the composition solidifies after storage at 60°C for 24 hours. Therefore, in the invention described in Patent Document 2 (that is, the radical curable composition containing an accelerator), the role of 1,4-naphthoquinone used as a polymerization inhibitor can be said to be storage stability.

[0008] As described above, there are not many known suitable methods for suppressing the gelation of maleimides and maintaining the maleimides in a molten state until the initiation of polymerization, and there is a strong demand for the development of a gelation inhibitor for maleimides that can suppress the gelation of maleimides. In particular, there is a strong demand for the development of a gelation inhibitor that can arbitrarily extend the gel time of maleimides.

[0009] The present invention has been made in consideration of the problems associated with the conventional techniques, and provides a gelation inhibitor for maleimides that can inhibit the gelation of maleimides, a composition containing the same, and a method for inhibiting the gelation of maleimides. [Means for solving the problem]

[0010] In view of the above situation, the present inventors have conducted extensive research into methods for suppressing gelation of maleimides, and have unexpectedly found that the above problem can be solved by adding 1,4-naphthoquinone to maleimides. Furthermore, they have also found that azanaphthoquinone compounds in which a part of the skeleton of a quinone compound is replaced by a nitrogen atom instead of a carbon atom, as well as azaanthraquinone compounds, phenanthrenequinone, and analogs thereof, exhibit the same or greater effect. Based on these findings, the present inventors have completed the present invention.

[0011] According to the present invention, there are provided a gelation inhibitor for maleimides, a composition containing the same, and a method for inhibiting the gelation of maleimides, as shown below.

[0012] [1] A gelation inhibitor for maleimides, which contains a quinone compound A having a condensed polycyclic aromatic skeleton and suppresses the gelation of maleimides.

[0013] [2] The gelation inhibitor for maleimides according to [1] above, which inhibits gelation of the maleimides when melted.

[0014] [3] The gelation inhibitor for maleimides according to [1] or [2], wherein the compound A comprises at least one selected from the group consisting of compounds represented by the following general formulas (1), (2), (3), (4), (5), and (6):

[0015] [ka] (In the general formula (1), X1 and X2 each represent a carbon atom or a nitrogen atom, Y and Z each represent a hydrogen atom, an alkyl group, a cyclic alkyl group or an aromatic group, m represents an integer of 1 to 4, and n represents an integer of 1 to 2, and may be the same or different.)

[0016] [ka] (In the general formula (2), X1, X2, X3, and X4 each represent a carbon atom or a nitrogen atom, Y and Z each represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, m represents an integer of 1 to 4, and n represents an integer of 1 to 4, and may be the same or different.)

[0017] [ka] (In the general formula (3), X1, X2, X3, and X4 each represent a carbon atom or a nitrogen atom, W, Y, and Z each represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, l represents an integer of 1 to 4, m represents an integer of 1 to 4, and n represents an integer of 0 to 2, and may be the same or different.)

[0018] [ka] (In the general formula (4), X1 and X2 each represent a carbon atom or a nitrogen atom, Y and Z each represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, m represents an integer of 1 to 4, and n represents an integer of 1 to 2, and may be the same or different.)

[0019] [ka] (In the general formula (5), X1, X2, X3, and X4 each represent a carbon atom or a nitrogen atom, Y and Z each represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, m represents an integer of 1 to 4, and n represents an integer of 1 to 4, and may be the same or different.)

[0020] [ka] (In the general formula (6), X1, X2, X3, and X4 each represent a carbon atom or a nitrogen atom, W, Y, and Z each represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, l represents an integer of 1 to 4, m represents an integer of 1 to 4, and n represents an integer of 0 to 2, and may be the same or different.)

[0021] [4] The gelation inhibitor for maleimides according to [1] or [2] above, wherein the maleimide is a bismaleimide compound.

[0022] [5] A composition comprising the gelation inhibitor for maleimides according to [1] or [2] above and a maleimide as a polymerizable compound.

[0023] [6] A composition comprising the gelation inhibitor for maleimides according to [1] or [2] above and a bismaleimide as a polymerizable compound.

[0024] [7] A step A of adding a quinone compound A having a condensed polycyclic aromatic skeleton as a gelation inhibitor to a powder of maleimide as a polymerizable compound to obtain a mixture; A method for inhibiting gelation of maleimides, comprising: a step B of heating the obtained mixture to melt the powdered maleimide.

[0025] [8] The method for suppressing gelation of maleimides according to [7] above, further comprising heating the powdered maleimide to a melting point or higher to melt the maleimide. Effect of the Invention

[0026] The gelation inhibitor for maleimides of the present invention can effectively inhibit the gelation of maleimides. For example, the gelation inhibitor can effectively control the gel time with a small amount of addition, so that the gel time of maleimides can be extended arbitrarily. In addition, the quinone compound A contained in the gelation inhibitor for maleimides of the present invention can be a compound composed of only carbon, hydrogen, and nitrogen atoms, like maleimides, and does not contain halogens, sulfur, phosphorus atoms, etc. as its component elements, so that no harmful gases are generated during decomposition. Furthermore, the above-mentioned compound A can be produced without using a special reaction apparatus or an expensive catalyst, and can be produced simply and inexpensively.

[0027] Furthermore, according to the method for inhibiting gelation of maleimides of the present invention, gelation of maleimides can be effectively inhibited in the step of melting powdered maleimides. For example, the gelation inhibitor added to powdered maleimides can effectively control the gel time with a small amount, making it possible to arbitrarily extend the gel time of the maleimides. [Brief description of the drawings]

[0028] [Figure 1] 1 is a differential scanning calorimetry (DSC) chart for Examples 19 to 21 and Comparative Example 11. [Diagram 2] 1 is a differential scanning calorimetry (DSC) chart for Comparative Examples 11 to 14. [Diagram 3] 1 is a differential scanning calorimetry (DSC) chart for Comparative Examples 11 and 15 to 17. [Figure 4] 1 is a differential scanning calorimetry (DSC) chart for Comparative Examples 11 and 18 to 20. [Diagram 5] 1 is a differential scanning calorimetry (DSC) chart for Comparative Examples 11 and 21 to 23. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] The following describes the embodiments of the present invention, but the present invention is not limited to the following embodiments. Therefore, it should be understood that the scope of the present invention includes any modifications and improvements to the following embodiments based on the ordinary knowledge of a person skilled in the art without departing from the spirit of the present invention.

[0030] (1) Gelling inhibitors for maleimides: The gelation inhibitor for maleimides of the present invention is intended to inhibit the gelation of maleimides, and contains a quinone compound A having a condensed polycyclic aromatic skeleton.

[0031] Such a gelation inhibitor for maleimides (hereinafter, also simply referred to as "gelation inhibitor") can effectively inhibit the gelation of maleimides. For example, the gelation inhibitor of the present invention can effectively control the gel time with a small amount of addition, and therefore can arbitrarily extend the gel time of maleimides.

[0032] In addition, the above-mentioned quinone compound A (hereinafter, also simply referred to as "compound A") can be a compound composed only of carbon, hydrogen, and nitrogen atoms, similar to maleimides, and does not contain halogen, sulfur, phosphorus atoms, etc. as its component elements, so it is a highly safe gelation inhibitor that does not generate harmful gases upon decomposition. Furthermore, the above-mentioned compound A can be produced without using a special reaction device or an expensive catalyst, and can be produced simply and inexpensively.

[0033] The quinone compound A may be any quinone compound having a condensed polycyclic aromatic skeleton having a quinone structure, but it is particularly preferable that the quinone compound A contains at least one compound selected from the group consisting of compounds represented by the following general formulas (1), (2), (3), (4), (5), and (6).

[0034] [ka] (In the general formula (1), X1 and X2 each represent a carbon atom or a nitrogen atom, Y and Z each represent a hydrogen atom, an alkyl group, a cyclic alkyl group or an aromatic group, m represents an integer of 1 to 4, and n represents an integer of 1 to 2, and may be the same or different.)

[0035] [ka] (In the general formula (2), X1, X2, X3, and X4 each represent a carbon atom or a nitrogen atom, Y and Z each represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, m represents an integer of 1 to 4, and n represents an integer of 1 to 4, and may be the same or different.)

[0036] [ka] (In the general formula (3), X1, X2, X3, and X4 each represent a carbon atom or a nitrogen atom, W, Y, and Z each represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, l represents an integer of 1 to 4, m represents an integer of 1 to 4, and n represents an integer of 0 to 2, and may be the same or different.)

[0037] [ka] (In the general formula (4), X1 and X2 each represent a carbon atom or a nitrogen atom, Y and Z each represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, m represents an integer of 1 to 4, and n represents an integer of 1 to 2, and may be the same or different.)

[0038] [ka] (In the general formula (5), X1, X2, X3, and X4 each represent a carbon atom or a nitrogen atom, Y and Z each represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, m represents an integer of 1 to 4, and n represents an integer of 1 to 4, and may be the same or different.)

[0039] [ka] (In the general formula (6), X1, X2, X3, and X4 each represent a carbon atom or a nitrogen atom, W, Y, and Z each represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, l represents an integer of 1 to 4, m represents an integer of 1 to 4, and n represents an integer of 0 to 2, and may be the same or different.)

[0040] The compounds represented by the above general formulas (1), (2), (3), (4), (5), and (6) will be described below.

[0041] X1 and X2 in the general formula (1) each represent a carbon atom or at least one nitrogen atom. Y and Z in the general formula (1) each represent, for example, a hydrogen atom; a straight-chain or branched C1-C6 alkyl group having 1 to 6 carbon atoms (hereinafter, the number of carbon atoms is abbreviated as "C1-C6" when the number of carbon atoms is 1 to 6, for example), such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, or an n-hexyl group; a cyclic C1-C6 alkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, or a cyclohexyl group; or an aromatic group such as a phenyl group, a 1-naphthyl group, or a 2-naphthyl group, and may be the same or different. The above-mentioned cyclic C1-C6 alkyl group may have a substituent such as a linear or branched C1-C6 alkyl group, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, etc.; a cyclic C1-C6 alkyl group, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. m is an integer of 1 to 4, and n is an integer of 1 to 2, and may be the same or different.

[0042] Specific examples of the compound represented by general formula (1) include 1,4-naphthoquinone, 2-methyl-1,4-naphthoquinone, 2,3-dimethyl-1,4-naphthoquinone, 5-methyl-1,4-naphthoquinone, 6-methyl-1,4-naphthoquinone, 5,8-dimethyl-1,4-naphthoquinone, 6,7-dimethyl-1,4-naphthoquinone, quinoline-5,8-dione, and quinoxaline-5,8-dione.

[0043] X1, X2, X3, and X4 in the general formula (2) each represent a carbon atom or a nitrogen atom. Although not particularly limited, it is preferable that at least one of X1, X2, X3, and X4 in the compound represented by the general formula (2) is a nitrogen atom. Y and Z in the general formula (2) each represent, for example, a hydrogen atom; a linear or branched C1-C6 alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, or an n-hexyl group; a cyclic C1-C6 alkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, or a cyclohexyl group; or an aromatic group such as a phenyl group, a 1-naphthyl group, or a 2-naphthyl group, and may be the same or different. The above-mentioned cyclic C1-C6 alkyl group may have a substituent such as a linear or branched C1-C6 alkyl group, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, etc.; a cyclic C1-C6 alkyl group, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. m is an integer of 1 to 4, and n is an integer of 1 to 4, and may be the same or different.

[0044] Specific examples of the compound represented by the general formula (2) include anthraquinone, 1-methyl-anthraquinone, 2-methylanthraquinone, 1,2-dimethylanthraquinone, 2,3-dimethylanthraquinone, 2,3,7,8-tetramethylanthraquinone, 1-azaanthraquinone, 2-methyl-1-azaanthraquinone, 2,3-dimethyl-1-azaanthraquinone, 6-methyl-1-azaanthraquinone, 6,7-di Methyl-1-azaanthraquinone, 7-methyl-1-azaanthraquinone, 7,8-dimethyl-1-azaanthraquinone, 1,4-diazaanthraquinone, 2-methyl-1,4-diazaanthraquinone, 2,3-dimethyl-1,4-diazaanthraquinone, 6-methyl-1,4-diazaanthraquinone, 6,7-dimethyl-1,4-diazaanthraquinone, 7-methyl-1,4-diazaanthraquinone, 7,8-dimethyl-1,4 -diazaanthraquinone, 1,4,6-triazaanthraquinone, 2-methyl-1,4,6-triazaanthraquinone, 2,3-dimethyl-1,4,6-triazaanthraquinone, 6-methyl-1,4,6-triazaanthraquinone, 6,7-dimethyl-1,4,6-triazaanthraquinone, 7-methyl-1,4,6-triazaanthraquinone, 7,8-dimethyl-1,4,6-triazaanthraquinone, 1,4,6,9-tetramethyl-1,4,6-triazaanthraquinone, Examples of the tetraazaanthraquinone include 1,4,6,9-tetraazanthraquinone, 2-methyl-1,4,6,9-tetraazanthraquinone, 2,3-dimethyl-1,4,6,9-tetraazanthraquinone, 6-methyl-1,4,6,9-tetraazanthraquinone, 6,7-dimethyl-1,4,6,9-tetraazanthraquinone, 7-methyl-1,4,6,9-tetraazanthraquinone, and 7,8-dimethyl-1,4,6,9-tetraazanthraquinone.

[0045] X1, X2, X3, and X4 in the general formula (3) each represent a carbon atom or a nitrogen atom. Although not particularly limited, it is preferable that at least one of X1, X2, X3, and X4 in the compound represented by the general formula (3) is a nitrogen atom. W, Y, and Z in the general formula (3) each represent, for example, a hydrogen atom; a linear or branched C1-C6 alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, or an n-hexyl group; a cyclic C1-C6 alkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, or a cyclohexyl group; or an aromatic group such as a phenyl group, a 1-naphthyl group, or a 2-naphthyl group, and may be the same or different. The above-mentioned cyclic C1-C6 alkyl group may have a substituent such as a linear or branched C1-C6 alkyl group, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, etc.; a cyclic C1-C6 alkyl group, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. l is an integer of 1 to 4, m is an integer of 1 to 4, and n is an integer of 1 to 2, and may be the same or different.

[0046] Specific examples of the compound represented by the general formula (3) include 1-azatetracene-5,12-dione, 1-aza-2-methyltetracene-5,12-dione, 1-aza-3-methyltetracene-5,12-dione, 1-aza-4-methyltetracene-5,12-dione, 1-aza-6-methyltetracene-5,12-dione, 1-aza-7-methyltetracene-5,12-dione, 1-aza-8-methyltetracene-5,12-dione, 1-aza-9-methyltetracene-5,12-dione, and 1-aza-10-methyltetracene-5,12-dione. 1-aza-11-methyltetracene-5,12-dione, 6-azatetracene-5,12-dione, 6-aza-1-methyltetracene-5,12-dione, 6-aza-2-methyltetracene-5,12-dione, 6-aza-3-methyltetracene-5,12-dione, 6-aza-4-methyltetracene-5,12-dione, 6-aza-7-methyltetracene-5,12-dione, 6-aza-8-methyltetracene-5,12-dione, 6-aza-9-methyltetracene-5,12-dione, 6-aza-10-methyltetracene-5,12-dione, 6-aza 1,4-diaza-11-methyltetracene-5,12-dione, 1,4-diaza-2-methyltetracene-5,12-dione, 1,4-diaza-3-methyltetracene-5,12-dione, 1,4-diaza-6-methyltetracene-5,12-dione, 1,4-diaza-7-methyltetracene-5,12-dione, 1,4-diaza-8-methyltetracene-5,12-dione, 1,4-diaza-9-methyltetracene-5,12-dione, 1,4-diaza-10-methyltetracene-5,12-dione, 1,4-diaza -11-methyltetracene-5,12-dione, 6,11-diazatetracene-5,12-dione, 6,11-diaza-1-methyltetracene-5,12-dione, 6,11-diaza-2-methyltetracene-5,12-dione, 6,11-diaza-3-methyltetracene-5,12-dione, 6,11-diaza-4-methyltetracene-5,12-dione, 6,11-diaza-7-methyltetracene-5,12-dione, 6,11-diaza-8-methyltetracene-5,12-dione, 6,11-diaza-9-methyltetracene-5,12-dione, 6,Examples include 11-diaza-10-methyltetracene-5,12-dione.

[0047] In the compounds represented by the general formulae (1) to (3), the positions of the two ketone structures in the quinone compound are opposite positions (para positions) of the aromatic ring. Hereinafter, the compounds represented by the general formulae (1) to (3) may be referred to as 1,4-quinones. Such 1,4-quinones are not particularly limited, but aza-substituted 1,4-quinones are preferred.

[0048] X1 and X2 in the general formula (4) represent a carbon atom or a nitrogen atom. Y and Z in the general formula (4) represent, for example, a hydrogen atom; a linear or branched C1-C6 alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, or an n-hexyl group; a cyclic C1-C6 alkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, or a cyclohexyl group; or an aromatic group such as a phenyl group, a 1-naphthyl group, or a 2-naphthyl group, and may be the same or different. The above-mentioned cyclic C1-C6 alkyl group may have a substituent such as a linear or branched C1-C6 alkyl group, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, etc.; a cyclic C1-C6 alkyl group, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. m is an integer of 1 to 4, and n is an integer of 1 to 2, and may be the same or different.

[0049] Specific examples of the compound represented by general formula (4) include 1,2-naphthoquinone, 3-methyl-1,2-naphthoquinone, 4-methyl-1,2-naphthoquinone, 5-methyl-1,2-naphthoquinone, 6-methyl-1,2-naphthoquinone, 7-methyl-1,2-naphthoquinone, 8-methyl-1,2-naphthoquinone, 3,4-dimethyl-1,2-naphthoquinone, and 3,4-diphenyl-1,2-naphthoquinone.

[0050] X1, X2, X3, and X4 in the general formula (5) each represent a carbon atom or a nitrogen atom. Y and Z in the general formula (5) each represent, for example, a hydrogen atom; a linear or branched C1-C6 alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, or an n-hexyl group; a cyclic C1-C6 alkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, or a cyclohexyl group; or an aromatic group such as a phenyl group, a 1-naphthyl group, or a 2-naphthyl group, and may be the same or different. The above-mentioned cyclic C1-C6 alkyl group may have a substituent such as a linear or branched C1-C6 alkyl group, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, etc.; a cyclic C1-C6 alkyl group, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. m is an integer of 1 to 4, and n is an integer of 1 to 4, and may be the same or different.

[0051] Specific examples of the compound represented by general formula (5) include phenanthrenequinone, 1,10-phenanthroline-5,6-dione, 1-methylphenanthrenequinone, 2-methylphenanthrenequinone, 3-methylphenanthrenequinone, 4-methylphenanthrenequinone, 2-methyl-1,10-phenanthroline-5,6-dione, 3-methyl-1,10-phenanthroline-5,6-dione, and 4-methyl-1,10-phenanthroline-5,6-dione.

[0052] X1, X2, X3, and X4 in the general formula (6) each represent a carbon atom or a nitrogen atom. W, Y, and Z in the general formula (6) each represent, for example, a hydrogen atom; a linear or branched C1-C6 alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, or an n-hexyl group; a cyclic C1-C6 alkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, or a cyclohexyl group; or an aromatic group such as a phenyl group, a 1-naphthyl group, or a 2-naphthyl group, and may be the same or different. The above-mentioned cyclic C1-C6 alkyl group may have a substituent such as a linear or branched C1-C6 alkyl group, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, etc.; a cyclic C1-C6 alkyl group, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. l is an integer of 1 to 4, m is an integer of 1 to 4, and n is an integer of 1 to 2, and may be the same or different.

[0053] Specific examples of the compound represented by the general formula (6) include benzo[a]anthracene-5,6-dione, 1-methyl-benzo[a]anthracene-5,6-dione, 2-methyl-benzo[a]anthracene-5,6-dione, 3-methyl-benzo[a]anthracene-5,6-dione, 4-methyl-benzo[a]anthracene-5,6-dione, 7-methyl-benzo[a]anthracene-5,6-dione, 8-methyl-benzo[a]anthracene-5,6-dione, 9-methyl-benzo[a]anthracene-5,6-dione, and 10-methyl-benzo[a]anthracene. -5,6-dione, benzo[b][1,10]phenanthroline-5,6-dione, 2-methyl-benzo[b][1,10]phenanthroline-5,6-dione, 3-methyl-benzo[b][1,10]phenanthroline-5,6-dione, 4-methyl-benzo[b][1,10]phenanthroline-5,6-dione, 7-methyl-benzo[b][1,10]phenanthroline-5,6-dione, 8-methyl-benzo[b][1,10]phenanthroline-5,6-dione, 9-methyl-benzo[b][1,10]phenanthroline-5,6-dione, and the like.

[0054] In the compounds represented by the general formulae (4) to (6), the positions of the two ketone structures in the quinone compound are adjacent positions (ortho positions) of the aromatic ring. Hereinafter, the compounds represented by the general formulae (4) to (6) may be referred to as 1,2-quinones. Such 1,2-quinones are preferred in that they have a superior gel time extension effect compared to maleimides.

[0055] The compound A used in the gelation inhibitor of the present invention may be any one of the compounds represented by general formulas (1) to (6) used alone or a mixture of two or more of them.

[0056] The gelation inhibitor of the present invention is used to inhibit the gelation of maleimides and to arbitrarily extend the gel time of maleimides. There is no particular limitation on the maleimides that can be used with the gelation inhibitor of the present invention, and suitable examples include maleimide compounds such as maleimide and bismaleimide, which are conventionally known polymerizable compounds. For example, although not particularly limited, examples of maleimides that can be used include 4,4'-bismaleimidediphenylmethane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, bis-(3-ethyl-5-methyl-4-maleimidephenyl)methane, N,N'-1,2-phenylene dimaleimide, N,N'-1,3-phenylene dimaleimide, N,N'-1,4-phenylene dimaleimide, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, and N-phenylmaleimide.

[0057] The amount of gelation inhibitor to be added is not particularly limited, but may be, for example, 1 to 1000 ppm by mass, preferably 1 to 100 ppm by mass, and more preferably 1 to 50 ppm by mass, relative to the monomer (e.g., maleimides) as the polymerizable compound. For example, if the amount of gelation inhibitor to be added is less than 1 ppm by mass relative to the monomer, sufficient gelation inhibition effect may not be obtained. On the other hand, if the amount of gelation inhibitor to be added exceeds 1000 ppm by mass relative to the monomer, it is not preferable from an economical point of view. In addition, an appropriate amount of gelation inhibitor to be added may be determined in advance, for example, using a commercially available gel time measuring device or the like.

[0058] The gelation inhibitor of the present invention may be added to the powder of maleimides in advance, or a predetermined amount of gelation inhibitor may be added to the maleimides when the maleimides are used as a polymerizable compound (for example, before the maleimides are heated). When adding when the maleimides are used, it is preferable to add a predetermined amount of gelation inhibitor to the maleimide powder and mix them so that they are uniform. When adding the gelation inhibitor to the maleimides, it is preferable to appropriately adjust the amount of the gelation inhibitor added, taking into consideration the extension time of the gel time of the heated maleimides, for example, depending on the progress schedule of the subsequent steps. In particular, the gelation inhibitor of the present invention is preferably used to suppress the gelation of the maleimides when melted. For example, the melting point of bismaleimide is about 160°C, and when bismaleimide is used as a polymerizable compound, the temperature of the bismaleimide melted by heating may reach 200°C or more. The gelation inhibitor of the present invention is a gelation inhibitor for maleimides used to suppress the gelation of the maleimides in a melted state by heating as described above.

[0059] (2) Composition containing a gelation inhibitor: The composition of the present invention is a composition containing the gelation inhibitor described above and a maleimide or bismaleimide as a polymerizable compound.

[0060] The amount of gelation inhibitor to be added is not particularly limited, and can be appropriately selected in consideration of the induction period (gel time) from heating the maleimide or bismaleimide as the polymerizable compound until the start of curing, the time from heating until proceeding to the next step, etc. For example, the amount of gelation inhibitor to be added can be, for example, in the range of 1 to 1000 ppm by mass, preferably 1 to 100 ppm by mass, and more preferably 1 to 50 ppm by mass, relative to the monomer as the polymerizable compound.

[0061] As for the maleimide and bismaleimide as the polymerizable compound, the maleimide compounds described in the embodiment of the gelation inhibitor can be suitably used.

[0062] In the step of heating and melting the maleimide or bismaleimide (hereinafter also referred to as maleimides) as the polymerizable compound, the composition of the present invention preferably does not substantially contain any other components other than the gelation inhibitor. Here, "substantially does not contain" means that it is not actively mixed in except in the case of unavoidable mixing. After the maleimides in the composition are heated and melted, other raw materials may be added again to the composition containing the molten maleimides at the time of proceeding to the next step. In addition, after the other raw materials are added to the composition and mixed, a polymerization initiator or the like may be further added to promote polymerization of the raw materials.

[0063] (3) Method for inhibiting gelation of maleimides: Next, the method for inhibiting gelation of maleimides of the present invention will be described. The method for inhibiting gelation of maleimides of the present invention includes a step A of adding a quinone compound A having a condensed polycyclic aromatic skeleton as a gelation inhibitor to powdered maleimides as a polymerizable compound to obtain a mixture, and a step B of heating the obtained mixture to melt the powdered maleimides. According to such a method for inhibiting gelation of maleimides, the gelation of maleimides can be effectively inhibited in the step of melting the powdered maleimides. For example, the gelation inhibitor added to the powdered maleimides can effectively control the gel time with a small amount of addition, so that the gel time of the maleimides can be extended arbitrarily.

[0064] The gelation inhibitor, compound A, is highly safe as it does not generate harmful gases upon decomposition, and can be produced easily and inexpensively without using a special reaction device or an expensive catalyst. Compound A can be suitably the compound A described above in relation to the gelation inhibitor of the present invention.

[0065] The amount of compound A added as a gelation inhibitor is not particularly limited, and can be appropriately selected in consideration of the induction period (gel time) from heating maleimide or bismaleimide as a polymerizable compound until curing begins, the time until proceeding to the next step after heating, etc. For example, the amount of compound A added as a gelation inhibitor can be exemplified as 1 to 1000 ppm by mass, preferably 1 to 100 ppm by mass, and more preferably 1 to 50 ppm by mass, relative to the monomer as a polymerizable compound.

[0066] There is no particular restriction on the heating temperature in step B in which the powdered maleimides are melted. For example, in step B, it is preferable to heat the powdered maleimides to a temperature equal to or higher than the melting point of the maleimides to melt them. By configuring in this way, a molten composition of maleimides in which the powdered maleimides are melted can be obtained. Note that, after performing step B, other raw materials may be added again to the molten composition containing the molten maleimides as appropriate. In addition, after adding and mixing other raw materials to the molten composition containing the molten maleimides, a polymerization initiator or the like may be further added to promote polymerization of the raw materials. EXAMPLES

[0067] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, % indicates % by mass unless otherwise specified.

[0068] (Synthesis Example 1) [Production of quinoline-5,8-dione] In a 200 ml flask equipped with a magnetic stirrer, 13.2 g (41.4 mmol) of iodobenzene diacetate, 32 ml of acetonitrile, and 16 ml of water were added. Next, under a nitrogen atmosphere and in an ice bath, 2.0 g (13.8 mmol) of quinolin-5-ol was added and stirred for 2 hours. Then, 100 ml of water was further added and extracted with ethyl acetate. Ethyl acetate was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography to obtain 0.85 g of black crystals. The purity of quinoline-5,8-dione in the crystals was 87.6% by area percentage of HPLC. The yield was 26.6%. Hereinafter, the compound (quinoline-5,8-dione) obtained in Synthesis Example 1 is referred to as "Compound A1". Compound A1 is a compound represented by the above general formula (1), where X1 represents a nitrogen atom (N), X2 represents a carbon atom (C), Y and Z represent hydrogen atoms (H), m represents 3, and n represents 2. Table 1 shows the structure of compound A1 produced in Synthesis Example 1.

[0069] (Synthesis Example 2) [Production of 1,4-diazaanthraquinone] 0.47g (2.5mmol) of 2,3-diamino-1,4-naphthoquinone and 30ml of 10% acetic acid were added to a 100ml flask equipped with a magnetic stirrer. Next, 0.73g (5mmol) of 40% glyoxal aqueous solution was added and stirred at 80°C for 2 hours. Next, after cooling to room temperature, it was filtered under reduced pressure and washed with water. The solid matter obtained by the reduced pressure filtration was dried to obtain 0.45g of silvery white crystals. The purity of 1,4-diazaanthraquinone in these crystals was 94.9% by HPLC area percentage. The yield was 84.9%. Hereinafter, the compound (1,4-diazaanthraquinone) obtained in Synthesis Example 2 is referred to as "Compound A2". Compound A2 is a compound represented by the above general formula (2), where X1 and X2 represent nitrogen atoms (N), X3 and X4 represent carbon atoms (C), Y and Z represent hydrogen atoms (H), m represents 2, and n represents 4. Table 1 shows the structure of compound A2 produced in Synthesis Example 2.

[0070] (Synthesis Example 3) [Production of 1,4,6,9-tetraazaanthraquinone] In a 100 ml flask equipped with a magnetic stirrer, 0.84 g (5 mmol) of 2,3,5,6-tetraaminobenzoquinone and 60 ml of 10% acetic acid were added. Next, 2.19 g (15 mmol) of 40% glyoxal aqueous solution was added and stirred at 80°C for 2 hours. Next, after cooling to room temperature, it was neutralized with a 10% caustic aqueous solution and washed with ethyl acetate. Then, the aqueous phase was decompressed, and water was distilled off to obtain 0.17 g of brown crystals. The purity of 1,4,6,9-tetraazanathraquinone in these crystals was 99.8% by area percentage of HPLC. The yield was 16.5%. Hereinafter, the compound (1,4,6,9-tetraazanathraquinone) obtained in Synthesis Example 3 is referred to as "Compound A3". Compound A3 is a compound represented by the above general formula (2), in which X1, X2, X3, and X4 represent a nitrogen atom (N), Y and Z represent a hydrogen atom (H), m represents 2, and n represents 2. Table 1 shows the structure of compound A3 produced in Synthesis Example 3.

[0071] (Synthesis Example 4) [Production of 6-aza-11-methyltetracene-5,12-dione] In a 100 ml flask equipped with a magnetic stirrer, 3.16 g (10 mmol) of 1,4-naphthoquinone, 0.37 g (2 mmol) of copper (II) acetate, 1.62 g (12 mmol) of 2-acetylaniline, 10 ml of acetic acid, and 20 ml of ethanol were added, and the mixture was stirred at 70°C for 2 hours. Next, after cooling to room temperature, the mixture was filtered under reduced pressure, and 1.65 g of red crystals of 2-(2-acetylphenyl)amino-1,4-naphthoquinone was obtained in a yield of 56.6%. Next, 0.87 g (3 mmol) of the obtained red crystals, 2 ml of acetic acid, and 0.3 g (30 mmol) of concentrated sulfuric acid were added to a 100 ml flask equipped with a magnetic stirrer, and the mixture was refluxed for 15 minutes. Then, the reaction solution was transferred onto ice, extracted with ethyl acetate, and the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography, and 0.75 g of green crystals was obtained in a yield of 92.2%. The purity of 6-aza-11-methyltetracene-5,12-dione in the crystals was 91.7% by area percentage of HPLC. The yield of the series of steps described above was 52.2%. Hereinafter, the compound (6-aza-11-methyltetracene-5,12-dione) obtained in Synthesis Example 4 is referred to as "Compound A4". Compound A4 is a compound represented by the above general formula (3), where X1 represents a carbon atom (C), X2, X3, and X4 represent nitrogen atoms (N), Y represents a methyl group (CH3), Z represents a hydrogen atom (H), m represents 1, and n represents 4. Table 1 shows the structure of Compound A4 produced in Synthesis Example 4. In Table 1, the methyl group is abbreviated as Me.

[0072] (Synthesis Example 5) [Production of 1,10-phenanthroline-5,6-dione] In a 100 ml flask equipped with a magnet stirrer, 1.5 g (8.3 mmol) of 1,10-phenanthroline, 3.33 g (28 mmol) of potassium bromide, 10 ml of concentrated nitric acid, and 20 ml of sulfuric acid were added, and the mixture was stirred at 110° C. for 2 hours. After cooling to room temperature, the mixture was transferred onto ice, extracted with ethyl acetate, and the solvent was distilled off under reduced pressure to obtain 0.9 g of yellow crystals in a yield of 51.6%. The purity of 1,10-phenanthroline-5,6-dione in the crystals was 94.6% by area percentage of HPLC. Hereinafter, the compound (1,10-phenanthroline-5,6-dione) obtained in Synthesis Example 5 will be referred to as "Compound A5". Compound A5 is a compound represented by the above general formula (5), in which X1 and X3 represent nitrogen atoms (N), X2 and X4 represent carbon atoms (C), Y and Z represent hydrogen atoms (H), m represents 4, and n represents 4. Table 1 shows the structure of compound A5 produced in Synthesis Example 5.

[0073] [Gelling Inhibitor] In the present examples and comparative examples, in addition to the compounds A1 to A4 obtained in Synthesis Examples 1 to 5, phenanthrenequinone, 1,4-naphthoquinone, 1,4-benzoquinone, phenothiazine, hydroquinone, and TEMPO (2,2,6,6-tetramethylpiperazine-1-oxyl) were used as gelation inhibitors. 1,4-benzoquinone was a commercially available product manufactured by Anda City Sanjie Fine Chemical Technology Co., Ltd. Phenanthrenequinone, 1,4-naphthoquinone, phenothiazine, and TEMPO were commercially available products manufactured by Tokyo Chemical Industry Co., Ltd. Hydroquinone was a commercially available product manufactured by Kanto Chemical Industry Co., Ltd.

[0074] In addition, two types of maleimide powders were prepared as the gelation inhibitor: 4,4'-bismaleimidodiphenylmethane and 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane manufactured by K.I. Chemicals. In the "Maleimide" column of Table 1, the case where 4,4'-bismaleimidodiphenylmethane was used is marked "1," and the case where 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane was used is marked "2."

[0075] [Preparation of measurement samples] In this embodiment and comparative example, two types of measurement samples were prepared as measurement samples for measuring the gel time: measurement sample A with a gelation inhibitor content of 10 ppm by mass and measurement sample B with a gelation inhibitor content of 50 ppm by mass. Measurement sample A was prepared by the following method. First, 10 mg of gelation inhibitor was added to 9.99 g of maleimide powder and mixed uniformly in a mortar to obtain a primary sample with a gelation inhibitor content of 1000 ppm by mass. Measurement sample A with a gelation inhibitor content of 10 ppm by mass was prepared by diluting 10 mg of the obtained primary sample with 990 mg of maleimide powder. Measurement sample B was prepared by diluting 50 mg of the above-mentioned primary sample with a gelation inhibitor content of 1000 ppm by mass with 950 mg of maleimide powder so that the gelation inhibitor content was 50 ppm by mass. Hereinafter, measurement sample A and measurement sample B may be collectively referred to simply as "measurement sample".

[0076] [Measurement of gel time] In the present embodiment and comparative examples, the time until the maleimide powder gelled (gel time) was measured using the measurement sample prepared by the above-mentioned method. Specifically, the measurement sample was set in a measurement device (Madoka (product name) automatic curing time measurement device manufactured by Matsuo Sangyo Co., Ltd.), and the time until the maleimide powder gelled was measured. The measurement conditions were as follows: hot plate temperature: 200°C, torque judgment value: 1.5%, rotation speed: 200 rpm, revolution speed: 80 rpm, gap value: 0.2 mm, averaging points: 10, sample amount: 0.3 g.

[0077] Example 1 Using 1,4-naphthoquinone as a gelation inhibitor and 4,4'-bismaleimide diphenylmethane as maleimide powder, measurement sample A with a gelation inhibitor content of 10 mass ppm was prepared by the above-mentioned method. The gel time of the prepared measurement sample A was measured by the above-mentioned method. The results are shown in Table 1.

[0078] Example 2 Using 1,4-naphthoquinone as a gelation inhibitor and 4,4'-bismaleimide diphenylmethane as maleimide powder, measurement sample B with a gelation inhibitor content of 50 mass ppm was prepared by the above-mentioned method. The gel time of the prepared measurement sample B was measured by the above-mentioned method. The results are shown in Table 1.

[0079] (Examples 3 and 4) Compound A1 (quinoline-5,8-dione) was used as the gelation inhibitor, and 4,4'-bismaleimide diphenylmethane was used as the maleimide powder, and measurement sample A with a gelation inhibitor content of 10 ppm by mass and measurement sample B with a gelation inhibitor content of 50 ppm by mass were prepared by the above-mentioned method. The gel times of the prepared measurement sample A and measurement sample B were measured by the above-mentioned method. The results are shown in Table 1.

[0080] (Examples 5 and 6) Compound A2 (1,4-diazaanthraquinone) was used as the gelation inhibitor, and 4,4'-bismaleimidediphenylmethane was used as the maleimide powder, and measurement sample A with a gelation inhibitor content of 10 ppm by mass and measurement sample B with a gelation inhibitor content of 50 ppm by mass were prepared by the above-mentioned method. The gel times of the prepared measurement sample A and measurement sample B were measured by the above-mentioned method. The results are shown in Table 1.

[0081] (Examples 7 and 8) Compound A3 (1,4,6,9-tetraazaanthraquinone) was used as the gelation inhibitor, and 4,4'-bismaleimide diphenylmethane was used as the maleimide powder, and measurement sample A with a gelation inhibitor content of 10 ppm by mass and measurement sample B with a gelation inhibitor content of 50 ppm by mass were prepared by the above-mentioned method. The gel times of the prepared measurement sample A and measurement sample B were measured by the above-mentioned method. The results are shown in Table 1.

[0082] (Examples 9 and 10) Compound A4 (6-aza-11-methyltetracene-5,12-dione) was used as the gelation inhibitor, and 4,4'-bismaleimide diphenylmethane was used as the maleimide powder, and measurement sample A with a gelation inhibitor content of 10 ppm by mass and measurement sample B with a gelation inhibitor content of 50 ppm by mass were prepared by the above-mentioned method. The gel times of the prepared measurement sample A and measurement sample B were measured by the above-mentioned method. The results are shown in Table 1.

[0083] (Examples 11 and 12) Using phenanthrenequinone as the gelation inhibitor and 4,4'-bismaleimidediphenylmethane as the maleimide powder, measurement sample A with a gelation inhibitor content of 10 ppm by mass and measurement sample B with a gelation inhibitor content of 50 ppm by mass were prepared by the above-mentioned method. The gel times of the prepared measurement sample A and measurement sample B were measured by the above-mentioned method. The results are shown in Table 1.

[0084] (Examples 13 and 14) Compound A5 (1,10-phenanthroline-5,6-dione) was used as the gelation inhibitor, and 4,4'-bismaleimide diphenylmethane was used as the maleimide powder, and measurement sample A with a gelation inhibitor content of 10 ppm by mass and measurement sample B with a gelation inhibitor content of 50 ppm by mass were prepared by the above-mentioned method. The gel times of the prepared measurement sample A and measurement sample B were measured by the above-mentioned method. The results are shown in Table 1.

[0085] Comparative Example 1 A measurement sample was prepared using only maleimide powder, without using a gelation inhibitor, by using 4,4'-bismaleimide diphenylmethane as the maleimide powder. The gel time of the measurement sample was measured by the above method. The results are shown in Table 1.

[0086] (Comparative Examples 2 and 3) Using 1,4-benzoquinone as the gelation inhibitor and 4,4'-bismaleimidediphenylmethane as the maleimide powder, measurement sample A with a gelation inhibitor content of 10 ppm by mass and measurement sample B with a gelation inhibitor content of 50 ppm by mass were prepared by the above-mentioned method. The gel times of the prepared measurement sample A and measurement sample B were measured by the above-mentioned method. The results are shown in Table 1.

[0087] (Comparative Examples 4 and 5) Using phenothiazine as the gelation inhibitor and 4,4'-bismaleimidediphenylmethane as the maleimide powder, measurement sample A with a gelation inhibitor content of 10 ppm by mass and measurement sample B with a gelation inhibitor content of 50 ppm by mass were prepared by the above-mentioned method. The gel times of the prepared measurement sample A and measurement sample B were measured by the above-mentioned method. The results are shown in Table 1.

[0088] (Comparative Examples 6 and 7) Using hydroquinone as a gelation inhibitor and 4,4'-bismaleimidediphenylmethane as maleimide powder, measurement sample A with a gelation inhibitor content of 10 ppm by mass and measurement sample B with a gelation inhibitor content of 50 ppm by mass were prepared by the above-mentioned method. The gel times of the prepared measurement sample A and measurement sample B were measured by the above-mentioned method. The results are shown in Table 1.

[0089] (Comparative Examples 8 and 9) Using TEMPO as a gelation inhibitor and 4,4'-bismaleimidediphenylmethane as maleimide powder, measurement sample A with a gelation inhibitor content of 10 ppm by mass and measurement sample B with a gelation inhibitor content of 50 ppm by mass were prepared by the above-mentioned method. The gel times of the prepared measurement sample A and measurement sample B were measured by the above-mentioned method. The results are shown in Table 1.

[0090] Comparative Example 10 A measurement sample was prepared using only maleimide powder, without using a gelation inhibitor, by using 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane as the maleimide powder. The gel time of the measurement sample was measured by the above method. The results are shown in Table 1.

[0091] (Examples 15 and 16) Measurement samples A and B were prepared in the same manner as in Examples 1 and 2, except that 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane was used as the maleimide powder, and the gel time of each was measured. The results are shown in Table 1.

[0092] (Examples 17 and 18) Measurement sample A and measurement sample B were prepared in the same manner as in Examples 9 and 10, except that 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane was used as the maleimide powder, and the gel time of each was measured. The results are shown in Table 1.

[0093] [Table 1]

[0094] From the measurement results of the gel time in Examples 1 to 14 and Comparative Example 1, it was found that the gel time of 4,4'-bismaleimidediphenylmethane at 200°C was extended by adding a quinone compound having a condensed polycyclic aromatic skeleton (hereinafter also referred to as a "condensed polycyclic aromatic quinone compound") as a gelation inhibitor. Furthermore, the gelation inhibitors in Examples 1 to 14 had a higher gel time extension effect than 1,4-benzoquinone in Comparative Examples 2 and 3, phenothiazine in Comparative Examples 4 and 5, and hydroquinone in Comparative Examples 6 and 7, which are known as general polymerization inhibitors. In particular, Examples 3 and 4 using compound A1 (quinoline-5,8-dione), Examples 5 and 6 using compound A2 (1,4-diazaanthraquinone), Examples 7 and 8 using compound A3 (1,4,6,9-tetraazaanthraquinone), Examples 11 and 12 using phenanthrenequinone, and Examples 13 and 14 using compound A5 (1,10-phenanthroline-5,6-dione) showed a higher gel time extension effect than TEMPO in Comparative Examples 8 and 9.

[0095] It was also found that by using the gelation inhibitors of Examples 1 to 10 in the range of at least 10 to 50 ppm by mass, the gel time at 200° C. could be extended depending on the amount added.

[0096] From the results of measuring the gel time in Examples 15 to 18 and Comparative Example 10, it was confirmed that the gel time was extended even when 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane was used as the maleimide powder.

[0097] [Differential Scanning Calorimetry (DSC)] As Examples 19 to 21 and Comparative Examples 11 to 23, differential scanning calorimetry was performed on samples for differential scanning calorimetry prepared by the method described below. The differential scanning calorimetry was performed as follows. First, the prepared samples for differential scanning calorimetry were set in a measuring device (DSC-60 (product name) manufactured by Shimadzu Corporation) and heated at a rate of 10°C / min to perform differential scanning calorimetry. The amount of sample in the differential scanning calorimetry was about 5 mg. Differential scanning calorimetry (DSC) charts obtained by each differential scanning calorimetry are shown in Figures 1 to 5. In Figures 1 to 5, the horizontal axis indicates temperature (Temp [°C]) and the vertical axis indicates heat flow (heat flow; DSC [mW / mg]).

[0098] (Examples 19 to 21) A sample for differential scanning calorimetry was prepared using compound A2 (1,4-diazaanthraquinone) as a gelation inhibitor and 4,4'-bismaleimide diphenylmethane as a maleimide powder. In Example 19, the content of the gelation inhibitor was set to 10 ppm by mass, similar to the measurement sample A prepared in the measurement of the gel time. In Example 20, the content of the gelation inhibitor was set to 50 ppm by mass, similar to the measurement sample B prepared in the measurement of the gel time. In Example 21, the content of the gelation inhibitor was set to 1000 ppm by mass, similar to the primary sample prepared in the measurement of the gel time.

[0099] Comparative Example 11 A sample for differential scanning calorimetry was prepared from only the maleimide powder by using 4,4'-bismaleimidodiphenylmethane as the maleimide powder without using any gelation inhibitor.

[0100] (Comparative Examples 12 to 14) A sample for differential scanning calorimetry was prepared using 1,4-benzoquinone as a gelation inhibitor and 4,4'-bismaleimide diphenylmethane as a maleimide powder. In Comparative Example 12, the content of the gelation inhibitor was set to 10 ppm by mass, similar to Example 15. In Comparative Example 13, the content of the gelation inhibitor was set to 50 ppm by mass, similar to Example 16. In Comparative Example 14, the content of the gelation inhibitor was set to 1000 ppm by mass, similar to Example 17.

[0101] (Comparative Examples 15 to 17) A sample for differential scanning calorimetry was prepared using phenothiazine as a gelation inhibitor and 4,4'-bismaleimide diphenylmethane as a maleimide powder. In Comparative Example 15, the content of the gelation inhibitor was set to 10 ppm by mass, similar to Example 15. In Comparative Example 16, the content of the gelation inhibitor was set to 50 ppm by mass, similar to Example 16. In Comparative Example 17, the content of the gelation inhibitor was set to 1000 ppm by mass, similar to Example 17.

[0102] (Comparative Examples 18 to 20) A sample for differential scanning calorimetry was prepared using hydroquinone as a gelation inhibitor and 4,4'-bismaleimide diphenylmethane as a maleimide powder. In Comparative Example 18, the content of the gelation inhibitor was set to 10 ppm by mass, similar to Example 15. In Comparative Example 19, the content of the gelation inhibitor was set to 50 ppm by mass, similar to Example 16. In Comparative Example 20, the content of the gelation inhibitor was set to 1000 ppm by mass, similar to Example 17.

[0103] (Comparative Examples 21 to 23) A sample for differential scanning calorimetry was prepared using TEMPO as a gelation inhibitor and 4,4'-bismaleimide diphenylmethane as a maleimide powder. In Comparative Example 21, the content of the gelation inhibitor was set to 10 ppm by mass, similar to Example 15. In Comparative Example 22, the content of the gelation inhibitor was set to 50 ppm by mass, similar to Example 16. In Comparative Example 23, the content of the gelation inhibitor was set to 1000 ppm by mass, similar to Example 17.

[0104] 1, from the results of Examples 19 to 21 and Comparative Example 11, it was observed that the exothermic peak and polymerization initiation temperature indicating the polymerization of 4,4'-bismaleimidediphenylmethane were shifted to higher temperatures by using a condensed polycyclic aromatic quinone compound as a gelation inhibitor. It was found that the exothermic peak and polymerization initiation temperature were shifted to higher temperatures depending on the amount of gelation inhibitor added, at least in the range of 10 to 1000 ppm by mass.

[0105] 2, from the results of Comparative Examples 11 to 14, when 1,4-benzoquinone was used as the gelation inhibitor, no shift of the exothermic peak to the higher temperature side was observed at least in the range of addition of 10 to 50 ppm by mass (i.e., Comparative Examples 12 and 13). When 1000 ppm by mass was added (i.e., Comparative Example 14), a shift of the exothermic peak and the polymerization initiation temperature to the higher temperature side was observed, but compared to Example 17 described above, the shift of the exothermic peak and the polymerization initiation temperature was small.

[0106] As shown in FIG. 3, from the results of Comparative Examples 11, 15 to 17, when phenothiazine was used as the gelation inhibitor, a phenomenon was observed in which two exothermic peaks appeared in the range of 213 to 263°C when at least 10 to 50 ppm by mass was added (i.e., Comparative Examples 15 and 16). This split phenomenon in which two exothermic peaks appeared indicates that polymerization initiation and polymerization inhibition effects proceed simultaneously, and showed behavior that is clearly different from that of the gelation inhibitors such as those in Examples 15 to 17. On the other hand, when 1000 ppm by mass was added (i.e., Comparative Example 17), a shift in the exothermic peak and polymerization initiation temperature to the higher temperature side was observed.

[0107] 4, from the results of Comparative Examples 11, 18 to 20, when hydroquinone was used as a gelation inhibitor, a phenomenon was observed in which two exothermic peaks appeared in the range of 213 to 243°C when at least 10 to 50 ppm by mass was added (i.e., Comparative Examples 18 and 19), similar to the above-mentioned Comparative Examples 15 and 16. On the other hand, when 1000 ppm by mass was added (i.e., Comparative Example 20), a shift to a higher temperature for the exothermic peak and the polymerization initiation temperature was observed.

[0108] As shown in Fig. 5, from the results of Comparative Examples 11, 21 to 23, when a gelation inhibitor and TEMPO were used, a phenomenon in which two exothermic peaks appeared in the range of 213 to 243°C was observed, as in the above-mentioned Comparative Examples 15 and 16, when at least 10 ppm by mass was added (i.e., Comparative Example 21). Furthermore, when 50 ppm was added (i.e., Comparative Example 22), a shift of the exothermic peak to the lower temperature side by about 11°C was observed. When 1000 ppm by mass was added (i.e., Comparative Example 23), no shift of the exothermic peak or the polymerization initiation temperature to the higher temperature side was observed.

[0109] From the above results, it was found that when a condensed polycyclic aromatic quinone compound (e.g., phenanthrenequinone) is used as a gelation inhibitor, a higher gelation inhibition effect is exhibited in an addition range of at least 10 to 50 ppm by mass compared to existing polymerization inhibitors such as 1,4-benzoquinone, phenothiazine, hydroquinone, and TEMPO. [Industrial Applicability]

[0110] The gelation inhibitor for maleimides and the method for inhibiting gelation of maleimides of the present invention can be used to inhibit the gelation of molten maleimides. For example, the gelation inhibitor for maleimides of the present invention can effectively control the gel time with a small amount of addition, so that the gel time of the maleimides can be extended arbitrarily.

Claims

1. A gelation inhibitor for maleimides, which contains a quinone compound A having a condensed polycyclic aromatic skeleton and suppresses the gelation of maleimides.

2. The gelation inhibitor for maleimides according to claim 1 , which inhibits gelation of the maleimides when melted.

3. 3. The gelation inhibitor for maleimides according to claim 1 or 2, wherein the compound A comprises at least one selected from the group consisting of compounds represented by the following general formulas (1), (2), (3), (4), (5), and (6): 【Chemistry 1】 (In the general formula (1), X １ , X ２ represents a carbon atom or a nitrogen atom, Y and Z represent a hydrogen atom, an alkyl group, a cyclic alkyl group or an aromatic group, m represents an integer of 1 to 4, and n represents an integer of 1 to 2, which may be the same or different. 【Chemistry 2】 (In the general formula (2), X １ , X ２ , X ３ , X ４ represents a carbon atom or a nitrogen atom, Y and Z represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, m represents an integer of 1 to 4, and n represents an integer of 1 to 4, which may be the same or different. 【Chemistry 3】 (In the general formula (3), X １ , X ２ , X ３ , X ４ represents a carbon atom or a nitrogen atom, W, Y, and Z represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, l represents an integer of 1 to 4, m represents an integer of 1 to 4, and n represents an integer of 0 to 2, which may be the same or different. 【Chemistry 4】 (In the general formula (4), X １ , X ２ represents a carbon atom or a nitrogen atom, Y and Z represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, m represents an integer of 1 to 4, and n represents an integer of 1 to 2, which may be the same or different. 【Chemistry 5】 (In the general formula (5), X １ , X ２ , X ３ , X ４ represents a carbon atom or a nitrogen atom, Y and Z represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, m represents an integer of 1 to 4, and n represents an integer of 1 to 4, which may be the same or different. 【Chemistry 6】 (In the general formula (6), X １ , X ２ , X ３ , X ４ represents a carbon atom or a nitrogen atom, W, Y, and Z represent a hydrogen atom, an alkyl group, a cyclic alkyl group, or an aromatic group, l represents an integer of 1 to 4, m represents an integer of 1 to 4, and n represents an integer of 0 to 2, which may be the same or different.

4. 3. The gelation inhibitor for maleimides according to claim 1, wherein the maleimide is a bismaleimide compound.

5. A composition comprising the gelation inhibitor for maleimides according to claim 1 or 2 and a maleimide as a polymerizable compound.

6. A composition comprising the gelation inhibitor for maleimides according to claim 1 or 2 and a bismaleimide as a polymerizable compound.

7. a step A of adding a quinone compound A having a condensed polycyclic aromatic skeleton as a gelation inhibitor to a powder of maleimide as a polymerizable compound to obtain a mixture; A step B of heating the obtained mixture to melt the powdered maleimide.

8. 8. The method for inhibiting gelation of maleimides according to claim 7, wherein the powdered maleimide is melted by heating to a melting point or higher of the maleimide.

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