Cyanate ester compounds and methods for their production, resin composites, and cured products.

Abstract

Invention details;

Description

Cyanate ester compound, method for producing the same, resin composition, and cured product

[0001] The present invention relates to a cyanate ester compound, a method for producing the same, a resin composition, and a cured product thereof.

[0002] Cyanate ester compounds are known as thermosetting resins that form triazine rings upon curing. Cured products obtained from cyanate ester compounds have properties such as a high glass transition temperature, low dielectric constant and dielectric dissipation factor, and excellent electrical insulation and flame retardancy. Cyanate ester compounds have been widely used as raw materials for various functional polymer materials, such as structural composites, adhesives, electrical insulating materials, and electrical and electronic components.

[0003] Therefore, efforts are being made to develop cyanate esters with better properties and methods for producing them (for example, Patent Documents 1 and 2).

[0004] JP 2005-264154 A

[0005] However, with the cyanate ester compounds described in Patent Documents 1 and 2, it is difficult to control the polymerization reaction during the production of a cured product, and it is difficult to obtain a cured product having desired properties.

[0006] The present invention has been made in view of the above problems, and aims to provide a cyanate ester compound that is easy to control the polymerization reaction during production of a cured product and that is suitable for use in producing a cured product having desired properties, a method for producing the same, a resin composition, and a cured product.

[0007] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that the above-mentioned problems can be solved by using a specific cyanate ester compound, thereby completing the present invention.

[0008] That is, the present invention is as follows.

[0009] [1] A cyanate ester compound having two or more cyanate groups in the molecule, wherein the content of a compound having one carbamate group is 0.5 area % or less in terms of HPLC area percentage.

[0010] [2] The cyanate ester compound according to [1], wherein the cyanate ester compound is a compound represented by the following formula (1) or a compound represented by the following formula (2):

[0011]

[0012] (In formula (1), Ar １ each independently represents an aromatic ring; each Ra independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; １ b represents the number of cyanato groups bonded to Ar, each independently being an integer of 1 to 3; １ each independently represents the number of bonds of Ra to Ar １ represents the number obtained by subtracting (a+2) from the number of substitutable groups in the formula (1), c is an integer of 1 to 50, and each X independently represents a single bond, a divalent organic group having 1 to 50 carbon atoms in which a hydrogen atom may be substituted with a heteroatom, a divalent organic group having 1 to 10 nitrogen atoms, a carbonyl group, a carboxy group, a carbonyl dioxide group, a sulfonyl group, a divalent sulfur atom, or a divalent oxygen atom).

[0013]

[0014] (In formula (2), Ar ２ represents an aromatic ring; each Rb independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; d represents an Ar ２ represents the number of cyanato groups bonded to Ar, and is an integer of 2 or more and 3 or less; ２ indicates the number of bonds of Rb to Ar ２ This indicates the number of substitutable bases minus (d+2).

[0015] [3] In the formula (1), each X is independently represented by the following formula (3):

[0016]

[0017] (In formula (3), Ar ３ each independently represent an aromatic ring; Rc, Rd, Rg, and Rh each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms; Re and Rf each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; and f represents an integer of 0 to 5.

[0018]

[0019] (In formula (4), Ar ４ each independently represent an aromatic ring, Ri and Rj each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and g represents an integer of 0 to 5, and a divalent organic group having 1 to 50 carbon atoms represented by the following formulas (5) to (14):

[0020]

[0021] (in formula (8), h represents an integer of 4 or more and 7 or less, and in formula (13), each Rk independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms).

[0022] [4] The cyanate ester compound according to any one of [1] to [3], wherein the cyanate ester compound is a compound represented by the following formula (15) or a compound represented by the following formula (16):

[0023]

[0024] (In formula (15), Ar ５ each independently represents an aromatic ring; each Rl independently represents a methylene group, a methyleneoxy group, a methyleneoxymethylene group, an oxymethylene group, or a group in which two or more of these are linked together; each Rm and Rn independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; i represents an Ar５ j represents the number of cyanato groups bonded to Ar, each of which is independently an integer of 1 to 3, ５ indicates the number of bonds of Rm to Ar ５ k is the number obtained by subtracting (i+2) from the number of substitutable groups of Ar ５ indicates the number of bonds of Rn to Ar ５ 1 represents an integer of 1 or more, m represents an integer of 1 or more, and the arrangement of each repeating unit is arbitrary.

[0025]

[0026] (In formula (16), Ar ６ each independently represents an aromatic ring; each Ro independently represents a methylene group, a methyleneoxy group, a methyleneoxymethylene group, an oxymethylene group, or a group in which two or more of these are linked together; each Rp and Rq independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; n is a substituted or unsubstituted alkyl group; ６ represents the number of cyanato groups bonded to Ar, and is an integer of 2 or more and 3 or less; ６ indicates the number of bonds of Rp to Ar ６ p represents the number of substitutable groups of Ar ６ represents the number of bonds of Rq to Ar ６ represents a number obtained by subtracting 2 from the number of substitutable groups, and i represents an integer of 1 or more.

[0027] [5] The cyanate ester compound according to any one of [1] to [4], wherein the cyanate ester compound is a compound represented by the following formula (17):

[0028]

[0029] (In formula (17), n represents an integer of 1 or more and 50 or less).

[0030] [6] The cyanate ester compound according to any one of [1] to [5], wherein the compound having one carbamate group is a compound represented by the following formula (18):

[0031]

[0032] [7] A method for producing a cyanate ester compound according to any one of [1] to [6], comprising the steps of: reacting a cyanogen halide with a hydroxy-substituted aromatic compound in a mixed solvent containing hydrogen halide, an organic solvent, and water in the presence of a basic compound to cyanate the cyanate ester compound, thereby obtaining a reaction solution containing the cyanate ester compound; and separating the reaction solution into a first aqueous phase containing the hydrogen halide and the water and a first organic phase containing the cyanate ester compound and the organic solvent, such that a portion of the first aqueous phase is mixed into the first organic phase. 1. A production method comprising the steps of: obtaining a first solution having a second aqueous phase and a second organic phase; supplying water to the second aqueous phase to dilute the second aqueous phase, thereby obtaining a second solution having a third aqueous phase and a third organic phase; and separating the second solution into the third aqueous phase and the third organic phase so that a portion of the third aqueous phase is mixed into the third organic phase, thereby obtaining a third solution having a fourth aqueous phase and a fourth organic phase; wherein a hydrogen halide contamination rate in the fourth organic phase of the third solution relative to the amount of the hydroxy-substituted aromatic compound used is 1.00% or less.

[0033] [8] The method for producing a cyanate ester compound according to [7], wherein in the cyanation step, a cyanogen halide solution containing the cyanogen halide, the hydrogen halide, and the water is contacted with a solution A containing the hydroxy-substituted aromatic compound, the basic compound, and the organic solvent.

[0034] [9] The method for producing a cyanate ester compound according to [7] or [8], wherein in the cyanation step, a cyanogen halide solution containing the cyanogen halide, the hydrogen halide, and the water is contacted with a solution A containing the hydroxy-substituted aromatic compound, the basic compound, and the organic solvent to obtain a solution B, and then a solution C containing the basic compound and the organic solvent is poured into the solution B.

[0035]

[10] The method for producing a cyanate ester compound according to any one of [7] to [9], wherein in the cyanation step, the amount of the cyanogen halide used as a raw material is 0.5 mol or more and 5.0 mol or less per 1 mol of hydroxy groups of the hydroxy-substituted aromatic compound.

[0036]

[11] The method for producing a cyanate ester compound according to [7], wherein the temperature of the mixed solvent in the cyanation step is 5.0°C or lower.

[0037]

[12] A resin composition comprising the cyanate ester compound according to any one of [1] to [6].

[0038]

[13] A cured product obtained by curing the resin composition according to

[12] .

[0039] According to the present invention, it is possible to provide a cyanate ester compound that is easy to control the polymerization reaction during production of a cured product and that is suitable for use in producing a cured product having desired properties, a method for producing the same, a resin composition, and a cured product.

[0040] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0041] In this embodiment, unless otherwise specified, "resin solid content" or "resin solid content in a resin composition" refers to the resin components in a resin composition excluding fillers, additives (silane coupling agents, wetting and dispersing agents, curing accelerators, and other components), and solvents. "100 parts by mass of resin solid content" or "100 parts by mass of the total resin solid content in a resin composition" refers to 100 parts by mass of the total resin components in a resin composition excluding fillers, additives (silane coupling agents, wetting and dispersing agents, curing accelerators, and other components), and solvents.

[0042] In this specification, the substituent is not particularly limited, and examples thereof include halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom, hydroxy group, cyano group, nitro group, thiol group, heterocyclic group, linear aliphatic hydrocarbon group, branched aliphatic hydrocarbon group, cyclic aliphatic hydrocarbon group, aryl group, aralkyl group, alkoxy group, alkenyl group, acyl group, alkoxycarbonyl group, alkyloyloxy group, aryloyloxy group, and alkylsilyl group. Specific examples of these substituents may be found by referring to the examples of groups described in this specification.

[0043] [Cyanate Ester Compound] The cyanate ester compound of the present embodiment is a cyanate ester compound having two or more cyanato groups in the molecule, and the content of a compound having one carbamate group is 0.5 area % or less in terms of HPLC area percentage.

[0044] According to this embodiment, it is possible to provide a cyanate ester compound that is easy to control the polymerization reaction during production of a cured product and is suitable for use in producing a cured product having desired properties, and a resin composition containing the cyanate ester compound. By using the cyanate ester compound and resin composition of this embodiment, it is possible to suitably control the polymerization reaction during curing, making it easy to produce a cured product having properties suitable for the desired application. Although the reason for this is unclear, the inventors speculate as follows.

[0045] That is, a compound having one carbamate group tends to decompose into an amine compound when heated during curing. The amine compound promotes polymerization of the cyanate ester compound, but the content of the compound having one carbamate group in the cyanate ester compound of this embodiment is suitably controlled to be 0.5 area % or less in terms of HPLC area percentage. Therefore, the polymerization reaction during production of the cured product can be suitably controlled.

[0046] Therefore, the present inventors have presumed that the present embodiment can provide a cyanate ester compound that is easily controlled in the polymerization reaction during production of a cured product and that is suitable for use in producing a cured product having desired properties, and a resin composition containing the cyanate ester compound. However, the reason is not limited to this. The cyanate ester compound of the present embodiment can be suitably obtained, for example, by using the production method described below.

[0047] Since the polymerization reaction during production of a cured product can be more easily controlled and a cyanate ester compound that is more suitable for use in producing a cured product having desired properties can be obtained, the content of the compound having one carbamate group is preferably 0.4 area % or less, more preferably 0.3 area % or less, and even more preferably 0.2 area % or less, in terms of HPLC area percentage. The lower limit is not particularly limited, but considering the lower limit of HPLC quantitation, it is usually 0.001 area % or more.

[0048] The content of the compound having one carbamate group is measured using high-performance liquid chromatography (HPLC). Examples of such a measurement method include a method for measuring the content under the following conditions; for specific measurement methods, see the description in the Examples. Specifically, 0.3 g of the resulting 2-butanone solution containing 50% by mass of the cyanate ester compound is dissolved in 100 g of tetrahydrofuran (solvent) to obtain a solution. 2.0 μL of this solution is injected into a high-performance liquid chromatograph for analysis. Measurement conditions include, for example, a TSKgel ODS-120T (length 25 cm × inner diameter 4.6 mm) column manufactured by Tosoh Corporation, acetonitrile / water (80 / 20 volume ratio) as the mobile phase, a flow rate of 1.0 mL / min, a detection wavelength of 274 nm, and a column temperature of 35°C. For example, when the cyanate ester compound is a compound represented by formula (17), under those conditions, a peak observed at a retention time (RT) of 5.6 minutes is considered to be a peak derived from a compound having one carbamate group (monocarbamate) represented by formula (18), and the content of the compound having one carbamate group (monocarbamate) in the cyanate ester compound is calculated from the peak area value.

[0049] An example of a compound having one carbamate group is a compound having a group represented by the following formula (19).

[0050]

[0051] In formula (19), R ｒ indicates an organic group or a hydrogen atom, and "-*" indicates a bonding site.

[0052] Examples of organic groups include groups containing one or more carbon atoms, or groups formed by removing one hydrogen atom from an organic compound. Examples of such organic groups include alkyl groups, cycloalkyl groups, alkoxy groups, aryl groups, aralkyl groups, alkylcarbonyl groups, alkoxycarbonyl groups, and alkylcarbonyloxy groups. These groups may have an ether bond or a carbonyl group.

[0053] In this embodiment, the compound having one carbamate group is a by-product generated when a solution containing a cyanate ester compound is heated and distilled to remove the solvent in a step subsequent to the separation step. Compounds having one carbamate group tend to be produced in greater amounts when heated in the presence of an acid such as hydrogen halide, as the hydration reaction of the cyanate group in the cyanate ester compound progresses. The compound having one carbamate group produced by this hydration reaction is a compound in which one hydroxy group of a hydroxy-substituted aromatic compound is substituted with a carbamate group and the other hydroxyl group is cyanated. In this case, the bonding site is bonded to the aromatic ring in the cyanate ester compound. The oxygen atom in "-*-O" in formula (19) is the oxygen atom in the hydroxy group. Hydroxy-substituted aromatic compounds will be described later.

[0054] Since the polymerization reaction during production of a cured product can be more easily controlled and a cyanate ester compound that is more suitable for producing a cured product having desired properties can be obtained, R ｒ It is preferable that the content of the compound having one carbamate group in which is a hydrogen atom is in the above range.

[0055] It is more preferable that the content of the compound represented by the following formula (18) as the compound having one carbamate group is in the above range, because this makes it easier to control the polymerization reaction during production of a cured product and allows for the production of a cyanate ester compound that is more suitably used for producing a cured product having desired properties.

[0056]

[0057] The cyanate ester compound is preferably a compound represented by the following formula (1) or a compound represented by the following formula (2), and more preferably a compound represented by formula (1), because it makes it easier to control the polymerization reaction during production of a cured product and provides a cyanate ester compound that is more suitably used for producing a cured product having desired properties.

[0058] (Compound Represented by Formula (1)) The compound represented by formula (1) is shown below.

[0059]

[0060] In formula (1), Ar １ each independently represents an aromatic ring; each Ra independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; １ b represents the number of cyanato groups bonded to Ar, each independently being an integer of 1 to 3; １ each independently represents the number of bonds of Ra to Ar １ represents the number obtained by subtracting (a+2) from the number of substitutable groups in formula (1), c is an integer of 1 to 50, and each X independently represents a single bond, a divalent organic group having 1 to 50 carbon atoms in which a hydrogen atom may be substituted with a hetero atom, a divalent organic group having 1 to 10 nitrogen atoms, a carbonyl group, a carboxy group, a carbonyl dioxide group, a sulfonyl group, a divalent sulfur atom, or a divalent oxygen atom. Each group in formula (1) may have a substituent.

[0061] In formula (1), Ar １ Each independently represents an aromatic ring. １ Examples of the aromatic ring represented by Ar include a phenyl group and a naphthyl group. Since the polymerization reaction during the production of a cured product can be more easily controlled and a cyanate ester compound that is more suitably used for the production of a cured product having desired properties can be obtained, １ is preferably a phenyl group.

[0062] Each Ra independently represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, an alkenyl group having from 2 to 6 carbon atoms, an aryl group having from 6 to 12 carbon atoms, or an alkoxy group having from 1 to 4 carbon atoms. Ra is preferably a hydrogen atom or an alkenyl group having from 2 to 6 carbon atoms, since this makes it easier to control the polymerization reaction during production of a cured product and results in a cyanate ester compound that is more suitably used for producing a cured product having desired properties.

[0063] Examples of alkyl groups having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, neopentyl, n-hexyl, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. The alkyl group may be linear, branched, or cyclic.

[0064] Examples of alkenyl groups having 2 to 6 carbon atoms include vinyl, allyl, butenyl, pentenyl, and hexenyl groups. Among alkenyl groups having 2 to 6 carbon atoms, alkenyl groups having 2 to 5 carbon atoms are preferred, as this allows for easier control of the polymerization reaction during production of a cured product, and results in a cyanate ester compound that is more suitable for use in producing a cured product having desired properties. The alkenyl group may be linear, branched, or cyclic.

[0065] Examples of the aryl group having 6 to 20 carbon atoms include a phenyl group and a naphthyl group.

[0066] Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. The alkoxy group may be linear, branched, or cyclic.

[0067] a is Ar １ a represents the number of cyanate groups bonded to the compound, and each independently represents an integer of 1 or more and 3 or less. a is preferably an integer of 1 or more and 2 or less, and more preferably 1, because this makes it easier to control the polymerization reaction during production of a cured product and allows for the production of a cyanate ester compound that is more suitably used for producing a cured product having desired properties.

[0068] b is Ar １ each independently represents the number of bonds of Ra to Ar １ This represents the number obtained by subtracting (a+2) from the number of substitutable bases.

[0069] c is an integer of 1 or more and 50 or less. c is preferably an integer of 1 or more and 10 or less, more preferably an integer of 1 or more and 5 or less, and even more preferably 1, because this makes it easier to control the polymerization reaction during production of a cured product and allows for the production of a cyanate ester compound that is more suitably used for producing a cured product having desired properties to be obtained.

[0070] Each X independently represents a single bond, a divalent organic group having from 1 to 50 carbon atoms in which a hydrogen atom may be substituted with a hetero atom, a divalent organic group having from 1 to 10 nitrogen atoms (-N-R-N-, where R represents an organic group), a carbonyl group (-CO-), a carboxy group (-C(=O)O-), a carbonyl dioxide group (-OC(=O)O-), a sulfonyl group (-SO ２ -), a divalent sulfur atom, or a divalent oxygen atom.

[0071] Examples of the divalent organic group having 1 to 50 carbon atoms in which a hydrogen atom may be substituted with a heteroatom include linking groups selected from the group consisting of divalent groups represented by formulas (3) to (14).

[0072] In order to more easily control the polymerization reaction during production of a cured product and obtain a cyanate ester compound that is more suitably used for producing a cured product having desired properties, X in the compound represented by formula (1) is preferably a cyanate ester compound represented by formula (3):

[0073]

[0074] (In formula (3), Ar ３ each independently represent an aromatic ring; Rc, Rd, Rg, and Rh each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms; Re and Rf each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; and f represents an integer of 0 to 5.

[0075]

[0076] (In formula (4), Ar ４each independently represent an aromatic ring, Ri and Rj each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and g represents an integer of 0 to 5, and a divalent organic group having 1 to 50 carbon atoms represented by the following formulas (5) to (14):

[0077]

[0078] (in formula (8), h represents an integer of 4 or more and 7 or less, and in formula (13), each Rk independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms).

[0079] In formulas (3) and (4), Ar ３ and Ar ４ As the aromatic ring represented by the formula: Ar １ In formulas (3) and (4), examples of the alkyl group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms represented by Rc, Rd, Rg, and Rh, and the alkyl group having 1 to 6 carbon atoms, the aryl group having 6 to 12 carbon atoms, and the alkoxy group having 1 to 4 carbon atoms represented by Re, Rf, Ri, and Rj include the same as those exemplified for Ra. Each group in formulas (3) and (4) may have a substituent.

[0080] Examples of the compound represented by formula (1) include bisphenol A cyanate, bisphenol E cyanate, and diallyl bisphenol A cyanate.

[0081] As the compound represented by formula (1), a compound represented by the following formula (15) is preferred, since it allows easier control of the polymerization reaction during production of a cured product and is more suitably used for producing a cured product having desired properties.

[0082]

[0083] In formula (15), Ar ５each independently represents an aromatic ring; each Rl independently represents a methylene group, a methyleneoxy group, a methyleneoxymethylene group, an oxymethylene group, or a group in which two or more of these are linked together; each Rm and Rn independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; i represents an Ar ５ j represents the number of cyanato groups bonded to Ar, each of which is independently an integer of 1 to 3, ５ indicates the number of bonds of Rm to Ar ５ k is the number obtained by subtracting (i+2) from the number of substitutable groups of Ar ５ indicates the number of bonds of Rn to Ar ５ where 1 is an integer of 1 or more, m is an integer of 1 or more, and the arrangement of the repeating units is arbitrary. Each group in formula (15) may have a substituent.

[0084] In formula (15), Ar ５ As the aromatic ring represented by the formula: Ar １ In formula (15), examples of the alkyl group having 1 to 6 carbon atoms, the aryl group having 6 to 12 carbon atoms, and the alkoxy group having 1 to 4 carbon atoms represented by Rm and Rn include the same as those exemplified for Ra. l represents an integer of 1 or more, preferably an integer of 1 to 10, and more preferably an integer of 1 to 5. m represents an integer of 1 or more, preferably an integer of 1 to 10, and more preferably an integer of 1 to 5.

[0085] (Compound Represented by Formula (2)) The compound represented by formula (2) is shown below.

[0086]

[0087] In formula (2), Ar ２ represents an aromatic ring; each Rb independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; d represents Ar ２represents the number of cyanato groups bonded to Ar, and is an integer of 2 or more and 3 or less; ２ indicates the number of bonds of Rb to Ar ２ The number of groups in formula (2) is calculated by subtracting (d+2) from the number of substitutable groups. Each group in formula (2) may have a substituent.

[0088] In formula (2), Ar ２ As the aromatic ring represented by the formula: Ar １ In formula (2), examples of the alkenyl group having from 2 to 6 carbon atoms, the aryl group having from 6 to 12 carbon atoms, and the alkoxy group having from 1 to 4 carbon atoms, represented by Rb, include the same groups as those exemplified for Ra.

[0089] The cyanate ester compound of the present embodiment is preferably a compound represented by the following formula (16).

[0090]

[0091] In formula (16), Ar ６ each independently represents an aromatic ring; each Ro independently represents a methylene group, a methyleneoxy group, a methyleneoxymethylene group, an oxymethylene group, or a group in which two or more of these are linked together; each Rp and Rq independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; n is a substituted or unsubstituted alkyl group; ６ represents the number of cyanato groups bonded to Ar, and is an integer of 2 or more and 3 or less; ６ indicates the number of bonds of Rp to Ar ６ p represents the number of substitutable groups of Ar ６ represents the number of bonds of Rq to Ar ６ and i represents an integer of 1 or greater. Each group in formula (16) may have a substituent.

[0092] In formula (16), Ar ６ As the aromatic ring represented by the formula: Ar １In formula (16), examples of the alkyl group having 1 to 6 carbon atoms, the aryl group having 6 to 12 carbon atoms, and the alkoxy group having 1 to 4 carbon atoms, represented by Rp and Rq, include the same as those exemplified for Ra. i represents an integer of 1 or more, preferably an integer of 1 to 10, and more preferably an integer of 1 to 5.

[0093] The compound represented by formula (1) is preferably a compound represented by formula (17) below, since it is easier to control the polymerization reaction during production of a cured product and is more suitable for use in producing a cured product having desired properties.

[0094]

[0095] In formula (17), n represents an integer of 1 or more and 50 or less. n is preferably an integer of 1 or more and 10 or less, since this makes it easier to control the polymerization reaction during production of a cured product, and results in a cyanate ester compound that is even more suitably used for producing a cured product having desired properties.

[0096] [Method for Producing Cyanate Ester Compound] The method for producing a cyanate ester compound of this embodiment includes a cyanation step (hereinafter also referred to as "cyanation step") of reacting a cyanogen halide with a hydroxy-substituted aromatic compound in the presence of a basic compound in a mixed solvent containing hydrogen halide, an organic solvent, and water to cyanate the compound, thereby obtaining a reaction solution containing a cyanate ester compound; and separating the reaction solution into a first aqueous phase (hereinafter referred to as "aqueous phase 1") containing hydrogen halide and water and a first organic phase (hereinafter referred to as "organic phase 1") containing a cyanate ester compound and an organic solvent, such that a portion of the aqueous phase 1 is mixed into the organic phase 1, thereby obtaining a first solution (hereinafter referred to as "solution 1") having a second aqueous phase (hereinafter referred to as "aqueous phase 2") and a second organic phase (hereinafter referred to as "organic phase 2"). a step of supplying water to aqueous phase 2 to dilute the aqueous phase 2, thereby obtaining a second solution (hereinafter referred to as "solution 2") having a third aqueous phase (hereinafter referred to as "aqueous phase 3") and a third organic phase (hereinafter referred to as "organic phase 3") (hereinafter also referred to as "aqueous phase dilution step"); and a step of separating solution 2 into aqueous phase 3 and organic phase 3 such that a portion of aqueous phase 3 is mixed into organic phase 3, thereby obtaining a third solution (hereinafter referred to as "solution 3") having a fourth aqueous phase (hereinafter referred to as "aqueous phase 4") and a fourth organic phase (hereinafter referred to as "organic phase 4") (hereinafter also referred to as "liquid separation step 2"), wherein the hydrogen halide contamination rate in organic phase 4 in solution 3 relative to the amount of hydroxy-substituted aromatic compound used is 1.00% or less.

[0097] By undergoing such specific steps, it is possible to preferably produce a cyanate ester compound in which the content of the compound having one carbamate group is 0.5 area % or less in terms of HPLC area percentage, the polymerization reaction during production of the cured product is easily controlled, and the cyanate ester compound is preferably used to produce a cured product having desired properties. Although the reason for this is unclear, the present inventors speculate as follows.

[0098] That is, the cyanate ester compound of this embodiment is obtained by cyanation of a cyanogen halide and a hydroxy-substituted aromatic compound in the presence of a basic compound as a desalting agent using a hydrogen halide-water coexistence method, which is a liquid-phase reaction. In the hydrogen halide-water coexistence method, the cyanate ester compound is obtained by extraction into the organic phase by liquid separation. However, when producing a cyanate ester compound on a commercial scale, it is usually difficult to separate the organic and aqueous phases at the interface. Therefore, during liquid separation, a portion of the aqueous phase is mixed into the organic phase, and as a result, the hydrogen halide contained in the aqueous phase is also mixed into the organic phase. If hydrogen halide is present in the organic phase, the hydrogen halide acts as an acid, and during the heating and distillation process after the liquid separation step, a hydration reaction of the cyanato group in the cyanate ester compound is triggered, which facilitates the production of a compound having one carbamate group.

[0099] Therefore, the production method of this embodiment includes a separation step 1, an aqueous phase dilution step, and a separation step 2 after the cyanation step. In this embodiment, the hydrogen halide concentration in the aqueous phase mixed into the organic phase is reduced at the end of the separation step, thereby suppressing the production of a compound having one carbamate group. More specifically, in this embodiment, a certain amount of aqueous phase containing hydrogen halide is mixed into the organic phase in separation step 1. However, by reducing the hydrogen halide concentration in the aqueous phase in the aqueous phase dilution step, the hydrogen halide concentration in the aqueous phase mixed into the organic phase in separation step 2 can be reduced compared to separation step 1. As a result, it is possible to control the hydrogen halide mixing ratio in the organic phase to the amount of hydroxy-substituted aromatic compound used to 1.00% or less. Therefore, the amount of hydrogen halide in the organic phase can be suitably reduced, and the hydration reaction of the cyanate group in the cyanate ester compound can be suitably suppressed during the heating distillation process after the separation step. This effectively suppresses the by-production of a compound having one carbamate group. The production method of this embodiment, in which a part of the aqueous phase is mixed with the organic phase in the separation step, allows for a larger recovery of the cyanate ester compound than a method in which an organic phase is mixed with the aqueous phase to obtain the cyanate ester compound. Furthermore, the production method of this embodiment mixes a smaller amount of organic solvent into the aqueous phase than a method in which an organic phase is mixed with the aqueous phase. Therefore, the production method of this embodiment is advantageous from the viewpoint of wastewater regulations.

[0100] From the above, the present inventors have presumed that the production method of this embodiment can preferably produce a cyanate ester compound in which the content of the compound having one carbamate group is 0.5 area % or less in terms of HPLC area percentage, which makes it easy to control the polymerization reaction during production of a cured product and is suitable for use in producing a cured product having desired properties, although the reason is not limited to this.

[0101] First, each step in the method for producing a cyanate ester compound will be described, and each component to be subjected to the cyanation step and the like will be described later.

[0102] [Cyanation Step] The method for producing a cyanate ester compound includes a cyanation step of reacting a cyanogen halide with a hydroxy-substituted aromatic compound in a mixed solvent containing hydrogen halide, an organic solvent, and water in the presence of a basic compound to cyanate the compound and thereby obtain a reaction solution containing a cyanate ester compound.

[0103] Examples of the method for reacting a cyanogen halide with a hydroxy-substituted aromatic compound in the presence of a basic compound include a method in which the cyanogen halide and the hydroxy-substituted aromatic compound are stirred in the presence of a basic compound to bring the two components into contact with each other and cause the reaction to occur.

[0104] The cyanation step is preferably a step in which a cyanide halide solution containing cyanide halide, hydrogen halide, and water (hereinafter also referred to as "cyanide halide solution") is contacted with and reacted with Solution A (hereinafter also referred to as "Solution A") containing a hydroxy-substituted aromatic compound, a basic compound, and an organic solvent to cyanate, thereby obtaining a reaction liquid containing a cyanate ester compound. Because the cyanation step is such a specific step, the content of the compound having one carbamate group is within the above range, making it easy to control the polymerization reaction during production of a cured product, and making it possible to more preferably produce a cyanate ester compound that is suitable for use in producing a cured product having desired properties.

[0105] In the cyanation step, the temperature of the mixed solvent and the reaction liquid is preferably 5.0° C. or lower, more preferably −20° C. or higher and 3.0° C. or lower, and even more preferably −10° C. or higher and 2.0° C. or lower. When the temperature of the mixed solvent and the reaction liquid is within the above range, the content of the compound having one carbamate group is within the above range, which makes it easier to control the polymerization reaction during production of a cured product, and tends to more preferably enable production of a cyanate ester compound that is suitably used for producing a cured product having desired properties.

[0106] In the cyanation step, the pressure inside the vessel is not particularly limited as long as a reaction liquid containing the desired cyanate ester compound is obtained. If necessary, an inert gas such as nitrogen, helium, or argon may be passed through the reaction system.

[0107] In the cyanation step, the cyanogen halide solution and solution A can be contacted in either a semi-batch or continuous flow manner. Specifically, examples of the contacting method include (a) a method in which solution A is added dropwise to the cyanogen halide solution being stirred and mixed, (b) a method in which the cyanogen halide solution is added dropwise to solution A being stirred and mixed, and (c) a method in which a portion of the cyanogen halide solution and a portion of solution A are supplied to a reaction vessel continuously or intermittently, alternately, or simultaneously. In these methods, the solution may be added dropwise in appropriate portions. For example, in method (a), solution A may be added dropwise in portions to the cyanogen halide solution being stirred and mixed. The number of separate additions is typically, for example, 2 to 5 times.

[0108] Among methods (a) to (c), method (a) is preferred. When method (a) is used as the contacting operation method, the content of the compound having one carbamate group is within the above range, making it easy to control the polymerization reaction during production of a cured product, and it is possible to more preferably produce a cyanate ester compound that is suitably used for producing a cured product having desired properties.

[0109] In the cyanation step, the reaction time is not particularly limited, but the dropwise addition time in the contacting operation of method (a) and method (b), and the contact time in the contacting operation of method (c) are preferably 1 minute to 20 hours, more preferably 3 minutes to 10 hours. Furthermore, it is preferable to subsequently stir the mixture for 10 minutes to 10 hours while maintaining the reaction temperature. By keeping the reaction time within the above range, the target cyanate ester compound tends to be obtained more efficiently, economically and industrially. The stirring method may be as described above.

[0110] Examples of the stirring method include a method using a known stirrer such as a stirring blade, a stirrer, a paddle, a ribbon, a screw, a mixer, etc. The stirring time may be determined by referring to the reaction time described above, and is preferably 1 minute to 20 hours, more preferably 3 minutes to 10 hours.

[0111] In the cyanation step, it is preferable to carry out cyanation by separately subjecting a cyanogen halide solution prepared by dissolving a cyanogen halide and a hydrogen halide in water, and Solution A prepared by dissolving a hydroxy-substituted aromatic compound and a basic compound in an organic solvent, to the step. By undergoing such a step, the content of the compound having one carbamate group falls within the above range, making it easier to control the polymerization reaction during production of a cured product, and it tends to be possible to more preferably produce a cyanate ester compound that is suitable for producing a cured product having desired properties.

[0112] The amounts of cyanogen halide and hydrogen halide blended in the cyanogen halide solution may refer to the amounts of hydrogen halide used and the amount of cyanogen halide charged as raw materials, respectively, described below. The amount of water used is preferably sufficient to dissolve the hydrogen halide. The cyanogen halide solution may also contain an organic solvent. The organic solvent contained in the cyanogen halide solution may be the same as or different from the organic solvent contained in solution A, but it is preferable that they be the same. When the cyanogen halide solution contains an organic solvent, the mass ratio of water to the organic solvent (water / organic solvent) is not particularly limited, but is preferably 1 / 100 to 100 / 1, more preferably 1 / 10 to 10 / 1, and even more preferably 1 / 5 to 5 / 1.

[0113] The content of the basic compound in Solution A may refer to the amount of the basic compound used, which will be described later. The content of the organic solvent is preferably an amount capable of dissolving the basic compound and the hydroxy-substituted aromatic compound. The content of the organic solvent is usually 50% by mass or more and 90% by mass or less, relative to 100% by mass of Solution A.

[0114] In Solution A, the content of the basic compound is preferably 0.1 mol to 8 mol, more preferably 0.5 mol to 3 mol, per mol of hydroxyl groups in the hydroxy-substituted aromatic compound. When the contents of the basic compound and the hydroxy-substituted aromatic compound are within the above ranges, the content of the compound having one carbamate group is also within the above range, which makes it easier to control the polymerization reaction during production of a cured product, and tends to more preferably produce a cyanate ester compound that is suitable for producing a cured product with desired properties.

[0115] More preferably, the cyanation step is a process in which a cyanogen halide solution containing cyanogen halide, hydrogen halide, and water is contacted with a solution A containing a hydroxy-substituted aromatic compound, a basic compound, and an organic solvent to cyanate the cyanate to obtain a solution B containing a cyanate ester compound, and then a solution C containing a basic compound and an organic solvent (hereinafter also referred to as "solution C") is poured into solution B to obtain a reaction solution. Adding solution C to solution B after obtaining solution B tends to enable the production of a high-purity cyanate ester compound in high yield. The reaction solution may also be obtained by pouring solution C into solution B to obtain solution D, and then stirring solution D to complete the reaction.

[0116] The basic compound and organic solvent contained in Solution C may be the same as or different from the basic compound and organic solvent contained in Solution A, respectively, but are preferably the same. The organic solvent contained in Solution C may be the same as or different from the organic solvent contained in the cyanogen halide solution, but are preferably the same. By having the cyanation step be such a specific step, the content of the compound having one carbamate group is within the above range, making it easy to control the polymerization reaction during production of a cured product, and making it possible to more preferably produce a cyanate ester compound that is suitable for use in producing a cured product having desired properties.

[0117] In Solution C, the amount of the basic compound is preferably 0.05 mol or more and 2.5 mol or less, more preferably 0.1 mol or more and 2.3 mol or less, per mol of hydroxy groups in the hydroxy-substituted aromatic compound. When the amount of the basic compound used is within the above range, the content of the compound having one carbamate group is within the above range, making it easier to control the polymerization reaction during production of a cured product, and tends to enable more preferable production of a cyanate ester compound suitable for producing a cured product having desired properties in high yield.

[0118] In Solution C, the organic solvent is preferably used in an amount sufficient to dissolve the basic compound. The content of the organic solvent is usually 50% by mass or more and 90% by mass or less relative to 100% by mass of Solution C.

[0119] The temperatures of the above-mentioned mixed solvent and reaction solution may be referred to for the temperature when Solution C is added to Solution B. Since a highly pure cyanate ester compound tends to be obtained in high yield, the temperature when Solution C is added to Solution B is preferably the same as the temperatures of the above-mentioned mixed solvent and reaction solution.

[0120] The pressure at which Solution C is added to Solution B is not particularly limited as long as the desired solution can be obtained. If necessary, an inert gas such as nitrogen, helium, or argon may be passed through the system.

[0121] The time for adding solution C to solution B is preferably 1 minute to 20 hours, more preferably 1.5 minutes to 10 hours. Furthermore, it is preferable to subsequently stir for 10 minutes to 10 hours while maintaining the same temperature as that at which solution C was added to solution B. When the time for adding solution C to solution B is within the above range, the target cyanate ester compound tends to be obtained economically and industrially more efficiently.

[0122] [Liquid Separation Step 1] The method for producing a cyanate ester compound includes a step of separating the reaction solution into an aqueous phase 1 containing hydrogen halide and water and an organic phase 1 containing a cyanate ester compound and an organic solvent such that a portion of the aqueous phase 1 is mixed into the organic phase 1, thereby obtaining a solution 1 containing an aqueous phase 2 and an organic phase 2.

[0123] The amount of aqueous phase 1 mixed into organic phase 1 is not particularly limited, but it is usually preferable that the amount of water in aqueous phase 1 be 1.0 part by mass or more and 10 parts by mass or less per 100 parts by mass of organic phase 1.

[0124] An example of a separation method is a method in which, in the separation step 1, separation is performed so that part of the aqueous phase 1 is mixed into the organic phase 1, and the organic phase 1 can be separated from the aqueous phase 1. Examples of such a separation method include a method in which the upper aqueous phase 1 and the lower organic phase 1 are separated using a separatory funnel at the laboratory level or a vessel such as a kettle at the actual equipment level, a method in which the aqueous phase 1 is removed using a pump, and an appropriate combination of these methods.

[0125] The temperature in the separation step 1 is preferably 15° C. or higher and 40° C. or lower, more preferably 20° C. or higher and 37° C. or lower, and even more preferably 25° C. or higher and 35° C. or lower. The temperature in the separation step 1 may be the same as or different from the temperatures in the aqueous phase dilution step and the separation step 2.

[0126] The pressure in the liquid separation step 1 is not particularly limited as long as the desired solution can be obtained. If necessary, an inert gas such as nitrogen, helium, or argon may be passed through the system.

[0127] [Aqueous Phase Dilution Step] The method for producing a cyanate ester compound includes a step of supplying water to an aqueous phase 2 to dilute the aqueous phase 2, thereby obtaining a solution 2 having an aqueous phase 3 and an organic phase 3. By supplying water to the aqueous phase 2 in the solution 1 obtained in the liquid separation step 1, it is possible to dilute the hydrogen halide in the aqueous phase 2 that is mixed into the organic phase 2.

[0128] The amount of water supplied to the aqueous phase 2 is not particularly limited, but it is usually preferable to set the amount of water to 50 parts by mass or more and 400 parts by mass or less per 100 parts by mass of the aqueous phase 2. When the amount of water supplied to the aqueous phase 2 is within the above range, the hydrogen halide in the aqueous phase 2 that is mixed into the organic phase 2 tends to be more sufficiently diluted.

[0129] The method for supplying water can be any known method for supplying water in separation, such as a laboratory method of supplying water from the top of a separatory funnel, or an actual system method of supplying water to a vessel such as a kettle using a pump, or an appropriate combination of these methods.

[0130] The temperature in the aqueous phase dilution step is preferably 15°C or higher and 40°C or lower, more preferably 20°C or higher and 37°C or lower, and even more preferably 25°C or higher and 35°C or lower.

[0131] The pressure in the aqueous phase dilution step is not particularly limited as long as the desired solution can be obtained. If necessary, an inert gas such as nitrogen, helium, or argon may be passed through the system.

[0132] As for the water, the water used in the cyanation step described below may be referred to.

[0133] After the aqueous phase dilution step, it is preferable to stir and mix the organic phase and the aqueous phase to obtain a solution 2 having an aqueous phase 3 and an organic phase 3. As for the stirring method, the above may be referred to.

[0134] [Liquid Separation Step 2] The method for producing a cyanate ester compound includes a step of separating solution 2 into an aqueous phase 3 and an organic phase 3 such that a portion of the aqueous phase 3 is mixed into the organic phase 3, thereby obtaining solution 3 having an aqueous phase 4 and an organic phase 4.

[0135] The amount of aqueous phase 3 mixed into organic phase 3 is not particularly limited, but it is usually preferable that the amount of water in aqueous phase 3 be 1.0 part by mass or more and 10 parts by mass or less per 100 parts by mass of organic phase 3.

[0136] Regarding the separation method, the temperature in the separation step 2, and the pressure in the separation step 2, reference can be made to the separation step 1 described above.

[0137] [Hydrogen Halide Contamination Rate] In the production method of the present embodiment, the hydrogen halide contamination rate in the organic phase 4 in the solution 3 is 1.00% or less relative to the amount of the hydroxy-substituted aromatic compound used. For a specific method for calculating the hydrogen halide contamination rate, see the description in the Examples.

[0138] According to the production method of this embodiment, it is possible to obtain a solution in which the amount of hydrogen halide in the organic phase is reduced, and therefore, in the heating distillation process after the separation step, it is possible to suitably suppress the hydration reaction of the cyanate group in the cyanate ester compound and suitably suppress the by-production of a compound having one carbamate group.

[0139] The hydrogen halide contamination rate is preferably 0.01% or more and 0.95% or less, and more preferably 0.01% or more and 0.90% or less.

[0140] [Other Steps] After the separation step 2, the target cyanate ester compound can be isolated by performing a typical post-treatment operation and, if desired, a separation operation and / or purification operation. Specifically, a solution 3 containing an organic phase 4 containing a cyanate ester compound and an aqueous phase 4 is heated and distilled to remove the cyanogen halide and the organic solvent. Thereafter, an organic solvent is further added, followed by washing with water and concentration, thereby precipitating or crystallizing the target cyanate ester compound. Alternatively, after washing with water and concentration, the solvent in the organic phase can be replaced with a solvent in which the cyanate ester compound is insoluble or poorly soluble, thereby precipitating or crystallizing the cyanate ester compound. During washing, an acidic aqueous solution such as a dilute hydrochloric acid may be used to remove excess amines. Furthermore, a drying operation using a common method using sodium sulfate, magnesium sulfate, or the like may be performed to remove water from the thoroughly washed organic phase.

[0141] Furthermore, during concentration and solvent substitution, in order to more suitably suppress polymerization of the cyanate ester compound, it is preferable to distill off the organic solvent under reduced pressure and heating at a temperature of 90°C or less. Precipitation or crystallization can be carried out by adding dropwise a solvent having low solubility for the cyanate ester compound to a solution containing the cyanate ester compound, or by adding dropwise a solution containing the cyanate ester compound to a solvent having low solubility for the cyanate ester compound. Examples of solvents having low solubility for the cyanate ester compound include ether-based solvents; hydrocarbon-based solvents such as hexane; and alcohol-based solvents.

[0142] To wash the obtained crude product, the concentrate of the reaction solution or the precipitated or crystallized crystals may be washed with a solvent having low solubility for the cyanate ester compound. The crystals obtained by concentrating the reaction solution may be redissolved and then recrystallized. When crystallization is desired, the reaction solution may simply be concentrated or cooled.

[0143] The purity of the obtained cyanate ester compound can be analyzed, for example, by liquid chromatography or FT-IR (Fourier transform infrared spectroscopy). By-products such as dialkylcyanoamide and volatile components such as residual solvents in the cyanate ester compound can be quantitatively analyzed by gas chromatography. Halides remaining in the cyanate ester compound can be identified by liquid chromatography-mass spectrometry and can be quantitatively analyzed by potentiometric titration using a silver nitrate solution or ion chromatography after decomposition by a combustion method. The polymerization reactivity of the cyanate ester compound can be evaluated by gelation time using a hot plate method or a torque measurement method.

[0144] Next, each component to be subjected to the cyanation step will be described.

[0145] (Hydrogen Halide) In the cyanation step, hydrogen halide is used to adjust the pH and suppress the by-production of impurities.

[0146] In the cyanation step, the pH of the reaction solution is preferably less than 7.0, more preferably 6.5 or less, and even more preferably 6.0 or less. The pH of the reaction solution may be appropriately adjusted while measuring the pH with a pH meter. In addition to hydrogen halide, the acid used may be, for example, an inorganic acid such as nitric acid, sulfuric acid, or phosphoric acid, or an organic acid such as acetic acid, lactic acid, or propionic acid.

[0147] Examples of hydrogen halides include hydrogen fluoride, hydrogen chloride, hydrogen bromide, and hydrogen iodide. The hydrogen halide may be an acidic aqueous solution such as hydrofluoric acid or hydrochloric acid. These hydrogen halides can be used alone or in combination of two or more.

[0148] When the content of the compound having one carbamate group is within the above range, the polymerization reaction during production of the cured product can be easily controlled, and a cyanate ester compound suitable for use in producing a cured product with desired properties can be more preferably produced. When the hydrogen halide is hydrochloric acid, its concentration in the reaction solution is preferably, for example, 1.0% or more and 10% or less. Using hydrochloric acid at such a concentration tends to produce a cyanate ester with high purity.

[0149] The amount of hydrogen halide used is preferably 0.5 mol or more and 5.0 mol or less, more preferably 1.0 mol or more and 3.5 mol or less, relative to 1 mol of hydroxy groups of the hydroxy-substituted aromatic compound. When the amount of hydrogen halide used is within the above range, the content of the compound having one carbamate group is within the above range, making it easier to control the polymerization reaction during production of a cured product, and tends to more preferably produce a cyanate ester compound that is suitably used for producing a cured product having desired properties.

[0150] (Organic Solvent) The organic solvent used in Solutions A, C, and the cyanogen halide solution can be any commonly known organic solvent that is immiscible with water and inert to the cyanation reaction. Examples of such organic solvents include halogenated hydrocarbon solvents such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, chlorobenzene, and bromobenzene; aliphatic solvents such as n-hexane, cyclohexane, and isooctane; aromatic solvents such as benzene, toluene, xylene, and ethylbenzene; ketone solvents such as methyl ethyl ketone, cyclohexanone, cyclopentanone, and methyl isobutyl ketone; nitrile solvents such as benzonitrile; nitro solvents such as nitrobenzene; ether solvents such as diethyl ether, diisopropyl ether, and tetrahydrofuran; and ester solvents such as ethyl acetate and ethyl benzoate. These organic solvents can be used alone or in combination of two or more. Among these, preferred organic solvents are halogenated hydrocarbon solvents having 1 to 2 carbon atoms, such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, and trichloroethane.

[0151] In this embodiment, as long as the effects of the present invention are achieved, the organic solvent may be mixed with the organic solvent described above, for example, a solvent miscible with water, etc. Examples of such organic solvents include acetone, dimethyl cellosolve, diglyme, tetraethylene glycol dimethyl ether, methanol, ethanol, isopropanol, methyl cellosolve, propylene glycol monomethyl ether, N,N-dimethylformamide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidone, dimethyl sulfoxide, and acetonitrile.

[0152] (Water) Examples of water include tap water, distilled water, and deionized water. Among these, it is preferable to use distilled water or deionized water with few impurities from the viewpoint of efficiently obtaining the target cyanate ester compound.

[0153] The total amount of solvents used in the cyanation step, i.e., the total amount of organic solvents and water used in Solutions A, C, and the cyanogen halide solution, is preferably 1.0 part by mass or more and 200 parts by mass or less, more preferably 1.5 parts by mass or more and 150 parts by mass or less, and even more preferably 2.5 parts by mass or more and 100 parts by mass or less, relative to 1 part by mass of the hydroxy-substituted aromatic compound. When the total amount of solvents is within the above range, the hydroxy-substituted aromatic compound can be uniformly dissolved, and the production efficiency of the cyanate ester compound tends to be further improved.

[0154] (Cyanogen Halide) In the cyanation step, a cyanogen halide is used to cyanate the hydroxy-substituted aromatic compound.

[0155] Examples of cyanogen halides include cyanogen fluoride, cyanogen chloride, cyanogen bromide, and cyanogen iodide. When the content of the compound having one carbamate group is within the above range, it is easy to control the polymerization reaction during production of a cured product, and a cyanate ester compound that is suitably used for producing a cured product having desired properties can be more preferably produced, and therefore cyanogen chloride is preferred as the cyanogen halide.

[0156] The amount of cyanogen halide used as a raw material is preferably 0.5 mol or more and 5 mol or less, more preferably 1.0 mol or more and 3.5 mol or less, relative to 1 mol of hydroxy groups in the hydroxy-substituted aromatic compound. When the amount of cyanogen halide used is within the above range, the content of the compound having one carbamate group is within the above range, making it easier to control the polymerization reaction during production of a cured product, and tends to more preferably produce a cyanate ester compound that is suitably used for producing a cured product with desired properties.

[0157] (Hydroxy-substituted aromatic compounds) Examples of hydroxy-substituted aromatic compounds include aromatic compounds having at least one phenolic hydroxy group. Examples of such hydroxy-substituted aromatic compounds include phenolic resins having a polynaphthylene ether structure and compounds represented by formula (27). Examples of compounds represented by formula (27) include (27a) 1-naphthol aralkyl resins, (27b) phenolic resins having an adamantane structure, and (27c) compounds other than (27a) and (27b) (hereinafter also referred to as "other hydroxy-substituted aromatic compounds"). These hydroxy-substituted aromatic compounds can be used alone or in combination of two or more.

[0158] Phenolic Resins Having a Polynaphthylene Ether Structure Examples of phenolic resins having a polynaphthylene ether structure include those having a polynaphthylene ether structure in which a naphthalene ring is bonded to another naphthalene ring via an oxy group, and a phenolic hydroxy group on the naphthalene ring. The total number of naphthalene rings per molecule is preferably 2 or more and 8 or less. The presence of a polynaphthylene ether structure promotes the formation of char (carbonized residue) during combustion of a cured product obtained from a cyanate ester, thereby exhibiting excellent flame retardancy and also improving heat resistance.

[0159] The number of oxy groups bonded to one naphthalene ring is preferably 1 to 3, and more preferably 2 from the viewpoint of the fluidity of the phenolic resin having a polynaphthylene ether structure. In this case, the bonding positions of the oxy groups on the naphthalene ring are preferably 1,3-positions, 1,6-positions, 1,7-positions, 1,8-positions, 2,3-positions, or 2,7-positions. Among these, from the viewpoint of ease of production, the bonding positions of the oxy groups on the naphthalene ring are more preferably 1,6-positions or 2,7-positions, and from the viewpoint of an excellent balance between fluidity and flame retardancy, the bonding positions are even more preferably 2,7-positions. Furthermore, with regard to the substituents on the naphthalene ring other than the oxy groups, from the viewpoint of flame retardancy, it is preferable that the naphthalene ring does not have such substituents.

[0160] The phenolic resin having a polynaphthylene ether structure may have a molecular structure in which a plurality of naphthalene rings form direct bonds.

[0161] Examples of the phenolic resin having a polynaphthylene ether structure include one or more selected from the group consisting of a compound represented by the following formula (21) and compounds represented by the following formulas (23) to (26) disclosed in Japanese Patent No. 4259536. As the phenolic resin having a polynaphthylene ether structure, a commercially available product may also be used, and an example of such a commercially available product is EXB-6000 from DIC Corporation.

[0162]

[0163] In formula (21), each R is independently a hydrogen atom, an aryl group such as a benzyl group, an alkyl group, or a group represented by the following formula (22), and n is an integer of 1 to 20, more preferably an integer of 1 to 10. Each group in formula (21) may have a substituent.

[0164]

[0165] In formula (22), each Ar is independently an aryl group such as a phenylene group or a naphthylene group, and m is an integer of 1 or 2.

[0166]

[0167]

[0168]

[0169]

[0170] A phenolic resin having a polynaphthylene ether structure can be obtained by a dehydration condensation reaction. The dehydration condensation reaction is a reaction in which, prior to the cyanation step, a polyhydroxynaphthalene compound having two or more phenolic hydroxy groups per molecule is subjected to a dehydration condensation reaction in the presence of a basic catalyst to obtain a hydroxy-substituted aromatic compound. The obtained hydroxy-substituted aromatic compound includes, for example, a phenolic resin having a structure in which a naphthalene ring is bonded to another naphthalene ring via an oxygen atom (hereinafter also referred to as an "oxy group") (hereinafter also referred to as a "polynaphthylene ether structure").

[0171] Examples of polyhydroxynaphthalene compounds used in the dehydration condensation reaction include dihydroxynaphthalenes such as 1,3-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, and 2,7-dihydroxynaphthalene; trihydroxynaphthalenes such as 1,2,3-trihydroxynaphthalene; and compounds of these compounds having an alkyl group having from 1 to 4 carbon atoms or a phenyl group as a substituent on the aromatic ring. These polyhydroxynaphthalene compounds can be used alone or in combination of two or more.

[0172] Examples of the basic catalyst used in the dehydration condensation reaction include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali metal carbonates such as sodium carbonate and potassium carbonate, and phosphorus compounds such as triphenylphosphine. These basic catalysts can be used alone or in combination of two or more.

[0173] The amount of the basic catalyst used can be appropriately selected depending on the type thereof, the target reaction rate, etc. For example, when an alkali metal hydroxide is used as the basic catalyst, the amount of the basic catalyst used is preferably 0.01 mol or more and 0.5 mol or less, more preferably 0.01 mol or more and 0.1 mol or less, per 1 mol of the phenolic hydroxy group of the polyhydroxynaphthalene compound.

[0174] The dehydration condensation reaction can be carried out in the absence of a solvent or in the presence of a solvent, depending on the polyhydroxynaphthalene compound used. Carrying out the reaction in the absence of a solvent eliminates the need for a solvent recovery step. Carrying out the reaction in the presence of a solvent also makes it easier to form a homogeneous reaction solution, which tends to facilitate stable reaction.

[0175] Examples of solvents used in the dehydration condensation reaction include alcohols such as benzyl alcohol, cyclohexanol, and amyl alcohol; ethylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, and polyethylene glycol; mono- or diethers of ethylene glycol and diethylene glycol such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol dipropyl ether; chlorobenzene, nitrobenzene, and the like. These solvents may be used alone or in combination of two or more. The use of such solvents prevents the precipitation of a salt of a polyhydroxynaphthalene compound during the dehydration condensation reaction, allowing for the stable production of a phenolic resin having a polynaphthylene ether structure.

[0176] The reaction temperature of the dehydration condensation reaction is preferably 100° C. or higher and 300° C. or lower, more preferably 150° C. or higher and 250° C. or lower. The reaction time is also preferably within a range in which the above reaction temperature conditions can be maintained, and is usually 1 minute or higher and 10 hours or lower. In the dehydration condensation reaction, from the viewpoint of rapidly progressing the reaction and further improving productivity, it is preferable to distill off water generated during the reaction in association with the dehydration condensation reaction to the outside of the system using a fractionating column or the like.

[0177] After the dehydration condensation reaction is completed, the product is solidified as it is to extract the phenolic resin having a polynaphthylene ether structure, or the catalyst in the product is removed by neutralization, water washing, or decomposition, and the phenolic resin having a polynaphthylene ether structure can be separated by a general operation such as extraction or distillation. The neutralization and water washing can be carried out according to a conventional method, and for example, an acidic substance such as hydrochloric acid, oxalic acid, acetic acid, sodium monophosphate, or carbon dioxide gas can be used.

[0178] The phenolic resin having a polynaphthylene ether structure thus obtained can be used for various applications as it is, but if necessary, a fractionation procedure such as distillation, column treatment, or extraction with an aqueous alkali solution may be carried out to reduce the content of unreacted polyhydroxynaphthalene compounds, or each product may be isolated as a single component.

[0179] Compound Represented by Formula (27) Next, the compound represented by the following formula (27) will be described.

[0180]

[0181] In formula (27), Ar １ each independently represents a phenylene group, a naphthylene group, or a biphenylene group; each Ra independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; １ m represents the number of hydroxy groups bonded to Ar, each independently being an integer of 1 to 3, １ each independently represents the number of bonds of Ra to Ar １ The number of substitutable groups is subtracted by (a+2), that is, Ar １is an integer of 4-1 when it is a phenylene group, an integer of 6-1 when it is a naphthylene group, and an integer of 8-1 when it is a biphenylene group; n is an integer of 0 to 50; and each X independently represents a single bond, a divalent organic group having 1 to 50 carbon atoms in which a hydrogen atom may be substituted with a heteroatom, a divalent organic group having 1 to 10 nitrogen atoms, a carbonyl group, a carboxy group, a carbonyl dioxide group, a sulfonyl group, a divalent sulfur atom, or a divalent oxygen atom. However, in formula (27), when n is 0, l is an integer of 2 to 3. Each group in formula (27) may have a substituent.

[0182] Ar １ each independently represents a phenylene group, a naphthylene group, or a biphenylene group in which a hydrogen atom at any position is substituted with an Ra group and a hydroxy group. These groups each may have a substituent.

[0183] In formula (27), examples of Ra and X include those similar to those exemplified as Ra and X in formula (1), and the repeating numbers 1, m, and n may refer to a, b, and c in formula (1), respectively.

[0184] X in formula (27) is preferably selected from the group consisting of divalent organic groups having 1 to 50 carbon atoms, as represented by the following formula (28), and divalent groups as represented by the following formulas (28a), (28b), (28c), (28d), (28e), (28f), (28g), (28h), (28i), and (28j).

[0185]

[0186] In formula (28), Ar ２each independently represent a phenylene group, a naphthylene group, or a biphenylene group, Rb, Rc, Rf, and Rg each independently represent a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, or an aryl group having from 6 to 12 carbon atoms, Rd and Re each independently represent a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, an aryl group having from 6 to 12 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, or a hydroxy group, and p represents an integer of from 0 to 5. Each group in formula (28) may have a substituent.

[0187]

[0188] In formula (28d), q represents an integer of 4 or more and 7 or less, and in formula (28i), each R independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0189] Ar in formula (28) ２ each independently represents a phenylene group, a naphthylene group, or a biphenylene group. ２ Examples of the alkyl group include a 1,4-phenylene group, a 1,3-phenylene group, a 2,6-naphthylene group, a 1,5-naphthylene group, a 1,6-naphthylene group, a 1,8-naphthylene group, a 1,3-naphthylene group, a 1,4-naphthylene group, a 4,4'-biphenylene group, a 2,4'-biphenylene group, a 2,2'-biphenylene group, a 2,3'-biphenylene group, a 3,3'-biphenylene group, and a 3,4'-biphenylene group.

[0190] Examples of Rb, Rc, Rd, Re, Rf, and Rg in formula (28) are the same as those exemplified for Rc, Rd, Re, Rf, Rg, and Rh in formula (3), respectively.

[0191] (27a) 1-Naphthol aralkyl resins Examples of 1-naphthol aralkyl resins include those having a structure in which a naphthalene ring having a hydroxyl group and a benzene ring are bonded via an alkyl group. Examples of such 1-naphthol aralkyl resins include those represented by the formula (27) where Ar １ is a naphthylene group, X is represented by formula (28), and Ar ２is a phenylene group. 1-Naphthol aralkyl resins are preferably compounds represented by the following formula (29). In the compound represented by formula (29), the two methylene groups bonded to the benzene ring can be bonded at the ortho, meta, or para positions. Of these, it is preferable that the two methylene groups bonded to the benzene ring are bonded to the meta and / or para positions of the benzene ring. By using such a 1-naphthol aralkyl resin, the content of the compound having one carbamate group is within the above range, making it easier to control the polymerization reaction during production of a cured product, and it tends to be possible to more preferably produce a cyanate ester compound that is suitable for producing a cured product having desired properties.

[0192]

[0193] In formula (29), n is an integer of 1 or more and 50 or less, and preferably an integer of 1 or more and 10 or less.

[0194] The 1-naphthol aralkyl resin can be prepared by, for example, reacting Ar ２ - (CH ２ Y) ２ and a naphthol compound in the presence of an acid catalyst or without a catalyst, ２ - (CH ２ OR) ２ Bis(alkoxymethyl) compounds represented by the formula: ２ - (CH ２ OH) ２ The compound can be obtained by reacting a bis(hydroxymethyl) compound represented by the following formula with a naphthol compound in the presence of an acid catalyst. Here, Y is a halogen atom, and R is an alkyl group. ２ is the same as that described in equation (28).

[0195] The 1-naphthol aralkyl resin may be a commercially available product, such as SN4 series phenolic resin (trade name, manufactured by Nippon Steel Chemical & Material Co., Ltd.).

[0196] (27b) Phenolic resin having an adamantane structure Examples of phenolic resins having an adamantane structure include those having a structure in which an aromatic ring having a hydroxy group is bonded to an adamantyl group. Examples of such phenolic resins include those in which, in formula (27), X is a group represented by formula (28i). Specific examples include compounds represented by the following formula (30). By using such compounds, the content of the compound having one carbamate group is within the above range, making it easier to control the polymerization reaction during the production of a cured product, and it tends to be possible to more preferably produce a cyanate ester compound that is suitable for producing a cured product with desired properties.

[0197]

[0198] In formula (30), Ar １ each independently represents a phenylene group, a naphthylene group, or a biphenylene group, R is the same as R in formula (28i), Ra is the same as Ra in formula (27), and l is Ar １ represents the number of hydroxy groups bonded to Ar, and is an integer of 1 to 3, １ represents the number of Ra bonded to Ar １ is an integer of 5-1 when it is a phenylene group, an integer of 7-1 when it is a naphthylene group, and an integer of 9-1 when it is a biphenylene group.

[0199] Examples of phenolic resins having such an adamantane structure include 1,3-bis(4-hydroxyphenyl)adamantane, 1,3-bis(4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(4-hydroxyphenyl)-5-methyladamantane, 1,3-bis(4-hydroxyphenyl)-5-ethyladamantane, 1,3-bis(4-hydroxyphenyl)-5-propyladamantane, 1,3-bis(4-hydroxyphenyl)-5-isopropyladamantane, and 1,3-bis(4-hydroxyphenyl)-5-isopropyladamantane. 1,3-bis(4-hydroxyphenyl)-5-t-butyladamantane, 1,3-bis(4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(4-hydroxyphenyl)-5-methyl-7-ethyladamantane, 1,3-bis(4-hydroxyphenyl)-5-methyl-7-propyladamantane, 1,3-bis(4-hydroxyphenyl)-5-ethyl-7-propyladamantane, 1,3-bis(4-hydroxyphenyl)-5,7-dipropyladamantane, 1,3-bis(4-hydroxyphenyl)-5-methyl-7-isopropyladamantane 1,3-bis(4-hydroxyphenyl)-5-ethyl-7-isopropyladamantane, 1,3-bis(4-hydroxyphenyl)-5-propyl-7-isopropyladamantane, 1,3-bis(4-hydroxyphenyl)-5,7-diisopropyladamantane, 1,3-bis(4-hydroxyphenyl)-5-methyl-7-t-butyladamantane, 1,3-bis(4-hydroxyphenyl)-5-ethyl-7-t-butyladamantane, 1,3-bis(4-hydroxyphenyl)-5-propyl-7-t-butyladamantane 1,3-bis(4-hydroxyphenyl)-5-isopropyl-7-t-butyladamantane, 1,3-bis(4-hydroxyphenyl)-5,7-di-t-butyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-methyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-ethyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-propyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-isopropyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-t-butyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-methyl-7-ethyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5,7-diethyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-methyl-7-propyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-ethyl-7-propyladamantane propyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5,7-dipropyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-methyl-7-isopropyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-ethyl-7-isopropyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-propyl-7-isopropyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5,7-diisopropyladamantane, 1,3-bis( 1,3-bis(3-methyl-4-hydroxyphenyl)-5-methyl-7-t-butyladamantane, 1,3-bis(3-methyl-4-dihydroxyphenyl)-5-ethyl-7-t-butyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-propyl-7-t-butyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5-isopropyl-7-t-butyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5,7-di-t-butyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5,7-di-t-butyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-methyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-ethyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-propyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-isopropyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-t-butyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(3,1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-methyl-7-ethyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5,7-diethyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-methyl-7-propyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-ethyl-7-propyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5,7-dipropyladamantane, 1,3-bis(3,5-dimethyl- 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-methyl-7-isopropyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-ethyl-7-isopropyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-propyl-7-isopropyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5,7-diisopropyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-methyl-7-t-butyladamantane, 1,3-bis(3 ,5-dimethyl-4-hydroxyphenyl)-5-ethyl-7-t-butyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-propyl-7-t-butyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5-isopropyl-7-t-butyladamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)-5,7-di-t-butyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-methyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-methyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-ethyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-propyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-isopropyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-t-butyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-methyl-7-ethyladamantane,

[0200] 1,3-bis(3-phenyl-4-hydroxyphenyl)-5,7-diethyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-methyl-7-propyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-ethyl-7-propyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5,7-dipropyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-methyl-7-isopropyladamantane, 1,3-bis(3-phenyl-4 -hydroxyphenyl)-5-ethyl-7-isopropyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-propyl-7-isopropyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5,7-diisopropyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-methyl-7-t-butyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-ethyl-7-t-butyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-methyl-7-t-butyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-propyl-7-t-butyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5-isopropyl-7-t-butyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5,7-di-t-butyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-methyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-ethyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5- Propyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-isopropyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-t-butyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-methyl-7-ethyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5,7-diethyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-methyl-7-propyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-ethyl-7-propyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5,7-dipropyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-methyl-7-isopropyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-ethyl-7-isopropyladamantane 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-propyl-7-isopropyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5,7-diisopropyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-methyl-7-t-butyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-ethyl-7-t-butyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-propyl-7 -t-butyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5-isopropyl-7-t-butyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5,7-di-t-butyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-methyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-ethyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-propyladamantane, 1,3-bis(4-methyl 1,3-bis(4-methyl-2-hydroxyphenyl)-5-isopropyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-t-butyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-methyl-7-ethyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5,7-diethyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-methyl-7-propyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-ethyl-7-propyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5,7-dipropyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-methyl-7-isopropyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-ethyl-7-isopropyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-propyl-7-isopropyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5,7-diisopropyladamantane Examples of such hydroxyphenyl compounds include 1,3-bis(4-methyl-2-hydroxyphenyl)-5-methyl-7-t-butyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-ethyl-7-t-butyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-propyl-7-t-butyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5-isopropyl-7-t-butyladamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)-5,7-di-t-butyladamantane, and 1,3-bis(2,4-dihydroxyphenyl)-adamantane.

[0201] (27c) Other Hydroxy-Substituted Aromatic Compounds Among the compounds represented by formula (27), examples of other hydroxy-substituted aromatic compounds other than 1-naphthol aralkyl resins and phenolic resins having an adamantane structure include 2,3-, 2,4-, 2,5-, 2,6-, 3,4-, or 3,5-xylenol, catechol, resorcinol, hydroquinone, 2-tert-butylhydroquinone, 2,4-dimethylhydroquinone, tetramethylhydroquinone, 2,4,6-trimethylresorcinol, 3,5-dihydroxytoluene, 2,2'-dihydroxy-1,1'-binaphthyl, 1, 3-, 1,4-, 1,5-, 1,6-, 1,7-, 2,3-, 2,6- or 2,7-dihydroxynaphthalene, 2,2'- or 4,4'-dihydroxybiphenyl, 4,4'-dihydroxyoctafluorobiphenyl, 2,2'- or 4,4'-dihydroxydiphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)methane 1,1-bis(4-hydroxyphenyl)propane, 2,2-bis(2-hydroxy-5-biphenylyl)propane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1,1-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)isobutane, 1,1-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)-3-methylbutane, 1,1-bis(4-hydroxyphenyl)-2-methylbutane, 1,1-bis(4 -hydroxyphenyl)-2,2-dimethylpropane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)pentane, 2,2-bis(4-hydroxyphenyl)hexane, 2,2-bis(4-hydroxyphenyl)-3-methylbutane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 2,2-bis(4-hydroxyphenyl)-3-methylpentane, 2,2-bis(4-hydroxyphenyl)-3,3-dimethylbutane, 3,3-bis(4-hydroxyphenyl)hexane, 3,3-bis(4-hydroxyphenyl)heptane, 3,3-bis(4-hydroxyphenyl)octane, 3,3-bis(4-hydroxyphenyl)-2-methylpentane, 3,3-bis(4-hydroxyphenyl)-2-methylhexane, 3,3-bis(4-hydroxyphenyl)-2,2-dimethylpentane, 4,4-bis(4-hydroxyphenyl)-3-methylheptane, 3,3-bis(4-hydroxyphenyl)-2-methylheptane, 3,3-bis(4-hydroxyphenyl)-2,2-dimethylhexane, 3,3-bis(4-hydroxyphenyl) bis(4-hydroxyphenyl)-2,4-dimethylhexane, 3,3-bis(4-hydroxyphenyl)-2,2,4-trimethylpentane, 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, bis(4-hydroxyphenyl)phenylmethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)biphenylmethane, 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(4-hydroxyphenyl)phenylmethane, 1,1-bis(3-cyclohexyl-4-hydroxyphenyl)propane, 1,1-bis(3-cyclohexyl-4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)diphenylmethane, bis(4-hydroxyphenyl)-2,2-dichloroethylene, 1,3-bis[2-(4-hydroxyphenyl)-2-propyl]benzene, 1,4-bis[2-(4-hydroxyphenyl)-2-propyl]benzene, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 4-[bis(4-hydroxyphenyl)methyl]biphenyl phenyl, 4,4'-dihydroxybenzophenone, 1,3-bis(4-hydroxyphenyl)-2-propen-1-one, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfone, 4-hydroxybenzoic acid-4-hydroxyphenyl ester (4-hydroxyphenyl-4-hydroxybenzoate), bis(4-hydroxyphenyl)carbonate, phenolphthalein, o-cresolphthalein, 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 9,9-bis(2-hydroxy-5-biphenylyl)fluorene, tris(4-hydroxyphenyl)methane, 1,1,1-tris(4-hydroxyphenyl)ethane, 1,1,3-tris(4-hydroxyphenyl)propane, α,α,α'-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 4,4 ',4'',4'''-Methanetetrayltetrakisphenol, 2,4,6-tris(N-methyl-4-hydroxyanilino)-1,3,5-triazine, 2,4-bis(N-methyl-4-hydroxyanilino)-6-(N-methylanilino)-1,3,5-triazine, bis(N-4-hydroxy-2-methylphenyl)-4,4'-oxydiphthalimide, bis(N-3-hydroxy-4-methylphenyl)-4,4'-oxydiphthalimide, bis(N-4- hydroxyphenyl)-4,4'-oxydiphthalimide, bis(N-4-hydroxy-2-methylphenyl)-4,4'-(hexafluoroisopropylidene)diphthalimide, tris(3,5-dimethyl-4-hydroxybenzyl)isocyanurate, 2-phenyl-3,3-bis(4-hydroxyphenyl)phthalimidine, 2-(4-methylphenyl)-3,3-bis(4-hydroxyphenyl)phthalimidine, 2-phenyl-3,3-bis(4-hydroxy-3-methylphenyl)phthalimidine, 1-methyl-3,3-bis(4-hydroxyphenyl)indolin-2-one, 2-phenyl-3,3-bis(4-hydroxyphenyl)indolin-2-one, phenol novolac resin, cresol novolac resin, phenol aralkyl resin, cresol aralkyl resin, biphenyl aralkyl resin, phenol-modified xylene formaldehyde resin, and phenol-modified dicyclopentadiene resin.

[0202] Examples of phenol novolac resins and cresol novolac resins include those obtained by reacting phenol, alkyl-substituted phenol, or halogen-substituted phenol with a formaldehyde compound such as formalin or paraformaldehyde in an acidic solution by a known method.

[0203] Phenol aralkyl resins, cresol aralkyl resins, and biphenyl aralkyl resins can be prepared by, for example, a method known in the art. ２ - (CH ２ Y) ２ and a phenol compound in the presence of an acid catalyst or without a catalyst, ２ - (CH ２ OR) ２ Bis(alkoxymethyl) compounds represented by the formula: ２ - (CH ２ OH) ２ and a phenol compound in the presence of an acid catalyst. Here, Y is a halogen atom. R is an alkyl group. ２ is the same as that described in equation (28).

[0204] Examples of phenol-modified xylene formaldehyde resins include those obtained by reacting a xylene formaldehyde resin with a phenol compound in the presence of an acid catalyst by a known method.

[0205] (Basic Compound) In the cyanation step, the basic compound used in Solutions A and C is used as a desalting agent in the cyanation of a cyanogen halide and a hydroxy-substituted aromatic compound. Examples of such basic compounds include organic bases and inorganic bases. The basic compound may be used in a solid state or in a solution state.

[0206] Preferred examples of the organic base include tertiary amines such as trimethylamine, triethylamine, tri-n-butylamine, triamylamine, diisopropylethylamine, diethyl-n-butylamine, methyldi-n-butylamine, methylethyl-n-butylamine, dodecyldimethylamine, tribenzylamine, triethanolamine, N,N-dimethylaniline, N,N-diethylaniline, diphenylmethylamine, pyridine, diethylcyclohexylamine, tricyclohexylamine, 1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0]-7-undecene, and 1,5-diazabicyclo[4.3.0]-5-nonene. Among these, the basic compound is more preferably one or more selected from the group consisting of trimethylamine, triethylamine, tri-n-butylamine, and diisopropylethylamine, and even more preferably triethylamine. By using such a basic compound, the content of the compound having one carbamate group falls within the above range, which makes it easier to control the polymerization reaction during the production of a cured product, and tends to enable the production of a cyanate ester compound that is preferably used for producing a cured product having desired properties to be more preferably carried out in high yield.

[0207] As the inorganic base, for example, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide are preferred. Among these, sodium hydroxide is more preferred from the viewpoint of inexpensive availability.

[0208] In the cyanation step, the amount (total amount) of the basic compound used in Solutions A and C is preferably 0.1 mol or more and 8.0 mol or less, more preferably 1.0 mol or more and 6.0 mol or less, relative to 1 mol of hydroxy groups in the hydroxy-substituted aromatic compound. When the amount of the basic compound used is within the above range, the content of the compound having one carbamate group is within the above range, making it easier to control the polymerization reaction during production of a cured product, and tends to enable more preferable production of a cyanate ester compound suitable for producing a cured product having desired properties in high yield.

[0209] In the cyanation step, the basic compound can be used as a solution dissolved in water or an organic solvent. When the basic compound is an organic base, it is preferable to use an organic solvent, and when the basic compound is an inorganic base, it is preferable to use water.

[0210] When the solution containing a basic compound contains a hydroxy-substituted aromatic compound, the content of the solvent in the solution containing the basic compound is preferably 0.10 parts by mass or more and 100 parts by mass or less, more preferably 0.10 parts by mass or more and 80 parts by mass or less, per part by mass of the hydroxy-substituted aromatic compound. This solution containing the basic compound becomes, for example, solution A in the cyanation step.

[0211] When the solution containing the basic compound does not contain a hydroxy-substituted aromatic compound, the content of the solvent in the solution containing the basic compound is preferably 0.10 parts by mass or more and 100 parts by mass or less per part by mass of the basic compound. Note that this solution containing the basic compound becomes, for example, solution C in the cyanation step.

[0212] Examples of organic solvents and water may be found above. The organic solvent is preferably immiscible with water and inert to the cyanation reaction. By using an organic solvent immiscible with water, an organic solvent layer containing the cyanate ester compound can be separated from the reaction solution, which is a mixture of organic solvent and water, at the end of the cyanation step, thereby enabling separation of the cyanate ester compound.

[0213] [Resin Composition] The resin composition of the present embodiment contains the cyanate ester compound of the present embodiment. The cyanate ester compound may be used alone or in combination of two or more.

[0214] The content of the cyanate ester compound is preferably 1.0 part by mass or more and 100 parts by mass or less per 100 parts by mass of the resin solid content in the resin composition. When the content of the cyanate ester compound is within the above range, the resin composition tends to have better heat resistance, low dielectric constant, low dielectric loss tangent, etc.

[0215] The resin composition may further contain, as necessary, one or more compounds selected from the group consisting of cyanate ester compounds other than the cyanate ester compound of this embodiment (hereinafter also referred to as "other cyanate ester compounds"), epoxy resins, oxetane resins, maleimide compounds, phenolic resins, benzoxazine compounds, compounds having a polymerizable unsaturated group, and fillers. By having the above-mentioned configuration, the resin composition can produce a cured product that is excellent in flame retardancy, low water absorbency, moisture absorption heat resistance, heat resistance, low thermal expansion, low dielectric properties, low dielectric loss tangent, etc.

[0216] (Epoxy Resin) The resin composition may contain an epoxy resin. When the resin composition contains an epoxy resin, it tends to have better adhesiveness, moisture absorption heat resistance, flexibility, and the like. As the epoxy resin, for example, a generally known compound having two or more epoxy groups in one molecule can be used. Specific examples thereof include bisphenol A type epoxy resin, bisphenol E type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol A novolac type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, xylene novolac type epoxy resin, multifunctional phenol type epoxy resin, naphthalene type epoxy resin, naphthalene skeleton-modified novolac type epoxy resin, naphthylene ether type epoxy resin, phenol aralkyl type epoxy resin, anthracene type epoxy resin, trifunctional phenol type epoxy resin, tetrafunctional phenol type epoxy resin, triglycidyl isocyanurate esters, glycidyl ester-type epoxy resins, alicyclic epoxy resins, dicyclopentadiene novolac-type epoxy resins, biphenyl novolac-type epoxy resins, phenol aralkyl novolac-type epoxy resins, naphthol aralkyl novolac-type epoxy resins, aralkyl novolac-type epoxy resins, biphenyl aralkyl-type epoxy resins, naphthol aralkyl-type epoxy resins, dicyclopentadiene-type epoxy resins, polyol-type epoxy resins, phosphorus-containing epoxy resins, glycidylamine, compounds in which the double bond of butadiene or the like has been epoxidized, compounds obtained by reacting hydroxyl-group-containing silicone resins with epichlorohydrin, or halides thereof. These epoxy resins may be used alone or in combination of two or more.

[0217] Among these, the epoxy resin is preferably at least one selected from the group consisting of biphenylaralkyl epoxy resins, naphthylene ether epoxy resins, polyfunctional phenolic epoxy resins, and naphthalene epoxy resins. When the resin composition contains such an epoxy resin, the flame retardancy and heat resistance of the resulting cured product tend to be further improved.

[0218] The content of the epoxy resin is preferably 0.0 part by mass or more and 99 parts by mass or less, more preferably 1.0 part by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the resin solid content in the resin composition. When the content of the epoxy resin is within the above range, the adhesiveness, flexibility, etc. tend to be more excellent.

[0219] (Oxetane Resin) The resin composition may contain an oxetane resin. When the resin composition contains an oxetane resin, the resin composition tends to have better adhesiveness, flexibility, and the like. As the oxetane resin, a generally known oxetane resin can be used. Specific examples include alkyl oxetanes such as oxetane, 2-methyloxetane, 2,2-dimethyloxetane, 3-methyloxetane, and 3,3-dimethyloxetane, 3-methyl-3-methoxymethyloxetane, 3,3'-di(trifluoromethyl)perfluoxetane, 2-chloromethyloxetane, 3,3-bis(chloromethyl)oxetane, biphenyl oxetane, OXT-101 (trade name, manufactured by Toagosei Co., Ltd.), and OXT-121 (trade name, manufactured by Toagosei Co., Ltd.). These oxetane resins can be used alone or in combination of two or more.

[0220] The content of the oxetane resin is preferably 0.0 part by mass or more and 99 parts by mass or less, and more preferably 1.0 part by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the resin solid content in the resin composition. When the content of the oxetane resin is within the above range, the resin composition tends to have better adhesion, flexibility, etc.

[0221] (Maleimide Compound) The resin composition may contain a maleimide compound. When the resin composition contains a maleimide compound, it tends to have better heat resistance, moisture absorption heat resistance, toughness, etc. As the maleimide compound, any generally known compound can be used as long as it has one or more maleimide groups in one molecule. Specific examples thereof include 4,4'-diphenylmethane bismaleimide, phenylmethane maleimide, m-phenylene bismaleimide, 2,2-bis(4-(4-maleimidophenoxy)-phenyl)propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6-bismaleimide-(2,2,4-trimethyl)hexane, 4,4'-diphenylether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 1,3-bis(3-maleimidophenoxy)benzene, 1,3-bis(4-maleimidophenoxy)benzene, polyphenylmethane maleimide, and prepolymers of these maleimide compounds, or prepolymers of maleimide compounds and amine compounds. These maleimide compounds can be used alone or in combination of two or more.

[0222] The content of the maleimide compound is preferably 0.0 part by mass or more and 99 parts by mass or less, and more preferably 1.0 part by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the resin solid content in the resin composition. When the content of the maleimide compound is within the above range, the heat resistance and the like tend to be more excellent.

[0223] (Phenolic Resin) The resin composition may contain a phenolic resin. When the resin composition contains a phenolic resin, the resin composition tends to have better adhesiveness, flexibility, and the like. As the phenolic resin, any commonly known phenolic resin having two or more hydroxy groups per molecule can be used. Specific examples include bisphenol A phenolic resin, bisphenol E phenolic resin, bisphenol F phenolic resin, bisphenol S phenolic resin, phenol novolac resin, bisphenol A novolac phenolic resin, aralkyl novolac phenolic resin, biphenyl aralkyl phenolic resin, cresol novolac phenolic resin, multifunctional phenolic resin, naphthol resin, naphthol novolac resin, multifunctional naphthol resin, anthracene phenolic resin, naphthalene skeleton-modified novolac phenolic resin, phenol aralkyl phenolic resin, naphthol aralkyl phenolic resin, dicyclopentadiene phenolic resin, biphenyl phenolic resin, alicyclic skeleton-containing phenolic resin, phosphorus-containing phenolic resin, and hydroxyl group-modified silicone resin. These phenolic resins can be used alone or in combination of two or more.

[0224] The content of the phenolic resin is preferably 0.0 parts by mass or more and 99 parts by mass or less, more preferably 1.0 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the resin solid content in the resin composition. When the content of the phenolic resin is within the above range, the adhesiveness, flexibility, etc. tend to be more excellent.

[0225] (Benzoxazine Compound) The resin composition may contain a benzoxazine compound. When the resin composition contains a benzoxazine compound, it tends to have better flame retardancy, heat resistance, low water absorption, low dielectric constant, and the like. As the benzoxazine compound, any generally known compound having two or more dihydrobenzoxazine rings in one molecule can be used. Specific examples include bisphenol A-type benzoxazine BA-BXZ (trade name, manufactured by Konishi Chemical Industry Co., Ltd.), bisphenol F-type benzoxazine BF-BXZ (trade name, manufactured by Konishi Chemical Industry Co., Ltd.), and bisphenol S-type benzoxazine BS-BXZ (trade name, manufactured by Konishi Chemical Industry Co., Ltd.). These benzoxazine compounds can be used alone or in combination of two or more.

[0226] The content of the benzoxazine compound is preferably 0.0 part by mass or more and 99 parts by mass or less, more preferably 1.0 part by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the resin solid content in the resin composition. When the content of the benzoxazine compound is within the above range, the heat resistance and the like tend to be more excellent.

[0227] (Compound Having a Polymerizable Unsaturated Group) The resin composition may contain a compound having a polymerizable unsaturated group. When the resin composition contains a compound having a polymerizable unsaturated group, the resin composition tends to have better heat resistance, toughness, and the like. As the compound having a polymerizable unsaturated group, generally known compounds can be used. Specific examples include vinyl compounds such as ethylene, propylene, styrene, divinylbenzene, and divinylbiphenyl; (meth)acrylates of monohydric or polyhydric alcohols such as methyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, polypropylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; epoxy(meth)acrylates such as bisphenol A-type epoxy(meth)acrylate and bisphenol F-type epoxy(meth)acrylate; and benzocyclobutene resins. These compounds having a polymerizable unsaturated group may be used alone or in combination of two or more.

[0228] The content of the compound having a polymerizable unsaturated group is preferably 0.0 part by mass or more and 99 parts by mass or less, more preferably 1.0 part by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the resin solid content in the resin composition. When the content of the compound having a polymerizable unsaturated group is within the above range, the heat resistance, toughness, etc. tend to be more excellent.

[0229] (Filler) The resin composition may contain a filler. When the resin composition contains a filler, it tends to have better flame retardancy, low thermal expansion, high thermal conductivity, toughness, etc. Examples of the filler include inorganic fillers and organic fillers. These fillers can be used alone or in combination of two or more.

[0230] As the inorganic filler, generally known ones can be used. Specific examples thereof include silicates such as kaolin, calcined kaolin, talc, calcined talc, calcined clay, uncalcined clay, mica, E glass, A glass, NE glass, C glass, L glass, D glass, S glass, M glass G20, glass short fiber (including glass fine powders such as E glass, T glass, D glass, S glass, and Q glass), hollow glass, and spherical glass; silicas such as white carbon (wet silica), natural silica, fused silica, synthetic silica, amorphous silica, aerosil, and hollow silica; oxides such as titanium oxide, alumina, boehmite, zinc oxide, magnesium oxide, and zirconium oxide; calcium carbonate, magnesium carbonate, hydrogel Examples of inorganic fillers include carbonates such as talcite; hydroxides such as aluminum hydroxide, heat-treated aluminum hydroxide (aluminum hydroxide that has been heat-treated to remove some of the water of crystallization), magnesium hydroxide, and calcium hydroxide; sulfates or sulfites such as barium sulfate, calcium sulfate, and calcium sulfite; borates such as zinc borate, barium metaborate, aluminum borate, calcium borate, and sodium borate; nitrides such as aluminum nitride, boron nitride, aggregated boron nitride, silicon nitride, and carbon nitride; titanates such as strontium titanate and barium titanate; stannates such as zinc stannate; and molybdenum compounds such as molybdenum oxide and zinc molybdate. These inorganic fillers can be used alone or in combination of two or more.

[0231] Examples of organic fillers include rubber powders such as styrene powder, butadiene powder, and acrylic powder; core-shell rubber powder; silicone resin powder; silicone rubber powder; silicone composite powder; etc. These organic fillers can be used alone or in combination of two or more.

[0232] The filler may be used in combination with a silane coupling agent or a wetting and dispersing agent. The resin composition may contain one or more agents selected from the group consisting of silane coupling agents and wetting and dispersing agents.

[0233] As the silane coupling agent, those generally used for the surface treatment of inorganic or organic substances can be suitably used. Specific examples include aminosilanes such as γ-aminopropyltriethoxysilane and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, epoxysilanes such as γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, vinylsilanes such as γ-methacryloxypropyltrimethoxysilane and vinyl-tri(β-methoxyethoxy)silane, cationic silanes such as N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane hydrochloride, and phenylsilanes. These silane coupling agents can be used alone or in combination of two or more.

[0234] As the wetting and dispersing agent, those generally used for paints can be suitably used. Preferably, a copolymer-based wetting and dispersing agent is used. Specific examples include Disperbyk (registered trademark)-110, 111, 161, 180 (all trade names), BYK (registered trademark)-W996, BYK-W9010, BYK-W903, BYK-W940 (all trade names) manufactured by BYK Japan K.K. These wetting and dispersing agents can be used alone or in combination of two or more.

[0235] The content of the filler is preferably 0.0 parts by mass or more and 1600 parts by mass or less, more preferably 50 parts by mass or more and 1600 parts by mass or less, relative to 100 parts by mass of the resin solid content in the resin composition. When the content of the filler is within the above range, the flame retardancy, low thermal expansion property, toughness, etc. tend to be better.

[0236] (Polymerization Catalyst and Curing Accelerator) In addition to the compounds or resins described above, the resin composition may further contain a polymerization catalyst and / or a curing accelerator for appropriately adjusting the curing rate. Generally known polymerization catalysts and curing accelerators can be used. Specific examples include organic metal salts such as zinc octylate, zinc naphthenate, cobalt naphthenate, copper naphthenate, iron acetylacetonate, nickel octylate, and manganese octylate; phenolic compounds such as phenol, xylenol, cresol, resorcinol, catechol, octylphenol, and nonylphenol; alcohols such as 1-butanol and 2-ethylhexanol; 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxyimidazole. Examples of the compound include imidazole derivatives such as methylimidazole; derivatives of these imidazoles such as adducts of carboxylic acids or acid anhydrides thereof; amine compounds such as dicyandiamide, benzyldimethylamine, and 4-methyl-N,N-dimethylbenzylamine; phosphorus compounds such as phosphine compounds, phosphine oxide compounds, phosphonium compounds, and diphosphine compounds; peroxides such as epoxy-imidazole adduct compounds, benzoyl peroxide, p-chlorobenzoyl peroxide, di-t-butyl peroxide, diisopropyl peroxycarbonate, and di-2-ethylhexyl peroxycarbonate; and azo compounds such as azobisisobutyronitrile. These polymerization catalysts and curing accelerators may be commercially available products, and examples of such commercially available products include Amicure (registered trademark) PN-23 (trade name, manufactured by Ajinomoto Fine-Techno Co., Inc.), Novacure (registered trademark) HX-3721 (trade name, manufactured by Asahi Kasei Corporation), and Fujicure (registered trademark) FX-1000 (trade name, manufactured by Fuji Chemical Industry Co., Ltd.). These polymerization catalysts and curing accelerators may be used alone or in combination of two or more.

[0237] The contents of the polymerization catalyst and curing accelerator can be adjusted as appropriate taking into consideration the degree of curing of the resin, the viscosity of the resin composition, etc., but are usually 0.005 parts by mass or more and 10 parts by mass or less, respectively, per 100 parts by mass of the resin solid content in the resin composition.

[0238] (Other Additives) The resin composition may contain additives other than the above-mentioned compounds or resins, polymerization catalysts, and curing rate enhancers, as needed. Examples of such additives include known additives such as thermosetting resins other than the above-mentioned compounds or resins, thermoplastic resins and their oligomers, various polymeric compounds such as elastomers, coloring pigments, defoamers, surface conditioners, flame retardants, solvents, UV absorbers, antioxidants, photopolymerization initiators, fluorescent brighteners, photosensitizers, dyes, pigments, thickeners, lubricants, flow adjusters, defoamers, dispersants, leveling agents, gloss agents, and polymerization inhibitors. These additives may be used alone or in combination of two or more.

[0239] The content of each additive is usually 0.005 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the resin solid content in the resin composition.

[0240] (Organic Solvent) The resin composition may contain an organic solvent as needed. In this case, the resin composition can be used in a form (solution or varnish) in which at least a part, preferably all, of the various resin components described above are dissolved or compatible with the organic solvent.

[0241] Any known organic solvent can be used as long as it is capable of dissolving or being compatible with at least a portion, preferably all, of the various resin components described above. Specific examples include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; cellosolve-based solvents such as propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate; ester-based solvents such as ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, isoamyl acetate, ethyl lactate, methyl methoxypropionate, and methyl hydroxyisobutyrate; polar solvents such as amides such as dimethylacetamide and dimethylformamide; alcohol-based solvents such as methanol, ethanol, isopropanol, and 1-ethoxy-2-propanol; and aromatic hydrocarbons such as toluene, xylene, and anisole. These organic solvents can be used alone or in combination of two or more.

[0242] The resin composition can be obtained by mixing the cyanate ester compound of the present embodiment and, as necessary, other components together with an organic solvent using a known mixer, for example, a high-speed mixer, a Nauta mixer, a ribbon blender, a kneader, an intensive mixer, a universal mixer, a dissolver, a static mixer, etc. The method of adding the cyanate ester compound, various additives, and the solvent during mixing is not particularly limited.

[0243] [Applications] The cyanate ester compound and resin composition of this embodiment are suitable for use in, for example, cured products, prepregs, laminates, metal foil-clad laminates, multilayer plates, sealing materials, fiber-reinforced composite materials, adhesives, resin composite sheets, films, and printed wiring boards. Furthermore, the cyanate ester compound and resin composition are useful as high-performance polymer materials due to, for example, their low thermal expansion, flame retardancy, and heat resistance. Furthermore, the cyanate ester compound and resin composition can be used as, for example, materials with excellent thermal, electrical, and mechanical properties. Examples of such materials include electrical insulating materials, sealing materials, adhesives, laminate materials, resists, and build-up laminate materials, as well as fixing materials, structural members, reinforcing agents, and molding materials in fields such as civil engineering and construction, electrical and electronics, automobiles, railways, ships, aircraft, sporting goods, and arts and crafts. Among these, the cyanate ester compound and resin composition are suitable for use in electrical insulating materials, semiconductor sealing materials, adhesives for electronic components, aircraft structural members, satellite structural members, and railway vehicle structural members, which require low thermal expansion, heat resistance, and high mechanical strength.

[0244] [Cured Product] The cured product of this embodiment is obtained by curing the resin composition of this embodiment. The cured product can be produced, for example, by melting or dissolving the resin composition in a solvent, pouring it into a mold, and curing it under normal conditions using heat, light, or the like. In the case of thermal curing, the curing temperature is preferably in the range of 120°C or higher and 300°C or lower, from the viewpoint of efficiently curing and preventing deterioration of the resulting cured product. In the case of photocuring, the light wavelength range is preferably in the range of 100 nm or higher and 500 nm or lower, in which curing efficiently proceeds using a photopolymerization initiator or the like.

[0245] [Prepreg] The prepreg includes a substrate and the resin composition of the present embodiment impregnated into or coated on the substrate. The prepreg can be used as an insulating layer for a printed wiring board and a material for a semiconductor package.

[0246] (Substrate) As the substrate, a generally known substrate can be appropriately selected and used depending on the performance required for the prepreg, such as strength, water absorption, and thermal expansion coefficient. Specific examples include glass fiber substrates, synthetic fiber substrates, organic fiber substrates, and inorganic fiber substrates. Examples of glass fibers constituting the glass fiber substrate include A-glass, C-glass, D-glass, E-glass, H-glass, L-glass, NE-glass, Q-glass, S-glass, T-glass, UN-glass, and spherical glass. Examples of synthetic fibers constituting the synthetic fiber substrate include polyamide-based resin fibers such as polyamide resin fibers, aromatic polyamide resin fibers, and wholly aromatic polyamide resin fibers; polyester-based resin fibers such as polyester resin fibers, aromatic polyester resin fibers, and wholly aromatic polyester resin fibers; polyimide resin fibers; and fluororesin fibers. Examples of organic fiber substrates include paper substrates primarily composed of kraft paper, cotton linter paper, and mixed paper of linter and kraft pulp. Examples of inorganic fibers constituting the inorganic fiber substrate include inorganic fibers other than glass, such as quartz. Examples of the substrate shape include woven fabric, nonwoven fabric, roving, chopped strand mat, and surfacing mat. The substrate can be used alone or in combination of two or more. Furthermore, the thickness of the substrate is preferably in the range of 0.01 mm to 0.2 mm for laminate applications. When the substrate is within the above thickness range, woven fabrics that have been subjected to an opening treatment or a clogging treatment are suitable from the viewpoint of dimensional stability. Furthermore, glass woven fabrics that have been surface-treated with a silane coupling agent such as epoxy silane treatment or amino silane treatment are preferred from the viewpoint of moisture absorption and heat resistance. Liquid crystal polyester woven fabrics are also preferred from the viewpoint of electrical properties.

[0247] As a method for producing a prepreg, a generally known method can be appropriately applied. For example, a prepreg can be produced by preparing a resin varnish using a resin composition and immersing a substrate in the resin varnish, applying the resin varnish to the substrate using various coaters, or spraying the resin varnish onto the substrate using a spray. Among these, the method of immersing the substrate in the resin varnish is preferred. This improves the impregnation of the resin composition into the substrate. When immersing the substrate in the resin varnish, a conventional impregnation coating device can be used. For example, a method can be applied in which an inorganic and / or organic fiber substrate is impregnated with the resin varnish using impregnation coating device, and the resin varnish is dried at 120°C to 220°C for approximately 2 minutes to 15 minutes, resulting in a B-stage to produce a prepreg. In this case, the amount of the resin composition attached to the substrate, i.e., the amount of the resin composition (including the filler) relative to the total amount (100% by mass) of the semi-cured prepreg, is preferably in the range of 20% by mass to 99% by mass.

[0248] [Laminate] A laminate has a layer containing at least one prepreg and metal foil laminated on one or both sides of the layer. A commonly known method can be appropriately applied as a method for manufacturing a laminate. For example, a laminate can be obtained by laminating a prepreg and a metal foil and then hot-pressing the laminate. The heating temperature is preferably 65°C or higher and 300°C or lower, more preferably 120°C or higher and 270°C or lower. The pressure applied is preferably 2.0 MPa or higher and 5.0 MPa or lower, more preferably 2.5 MPa or higher and 4.0 MPa or lower. The laminate can also be used as a metal foil-clad laminate or a multilayer board.

[0249] [Metal Foil-Clad Laminate] A metal foil-clad laminate is a laminate formed by stacking at least one prepreg and disposing a metal foil on one or both sides of the prepreg. Specifically, it can be produced by stacking one or more prepregs and disposing a metal foil such as copper or aluminum on one or both sides of the prepreg, followed by lamination molding. Examples of metal foil include those used in printed wiring board materials. Examples of such metal foils include copper foils such as rolled copper foil and electrolytic copper foil. The thickness of the metal foil is preferably 2.0 μm to 70 μm, more preferably 3.0 μm to 35 μm. Conventional methods for laminates and multilayer boards for printed wiring boards can be applied as molding conditions. For example, a multi-stage press, a multi-stage vacuum press, a continuous molding machine, an autoclave molding machine, or the like can be used at a temperature of 180°C to 350°C, a heating time of 100 minutes to 300 minutes, and a surface pressure of 20 kg / cm. ２ More than 100kg / cm ２ A metal foil-clad laminate can be manufactured by laminating and molding as follows.

[0250] [Multilayer board] A multilayer board can be obtained by combining prepreg and a separately prepared inner layer wiring board and laminating them together.As a method for producing a multilayer board, for example, 35 μm copper foil is placed on both sides of one prepreg, and then laminated under the above conditions, an inner layer circuit is formed, and this circuit is subjected to blackening treatment to form an inner layer circuit board.Then, this inner layer circuit board and the above prepreg are alternately arranged one by one, and copper foil is placed on the outermost layer, and laminated under the above conditions, preferably under vacuum, to produce the multilayer board.

[0251] [Sealing Material] The sealing material includes a resin composition. A generally known method can be appropriately applied as a method for producing the sealing material. For example, a method of mixing the resin composition with various known additives or solvents generally used in sealing material applications using a known mixer can be mentioned. Note that, when mixing, a generally known method can be appropriately applied as a method for adding the cyanate ester compound, various additives, and solvent.

[0252] [Fiber-reinforced composite material] The fiber-reinforced composite material contains a resin composition and reinforcing fibers. Generally known reinforcing fibers can be used. Specific examples include carbon fibers, glass fibers, aramid fibers, boron fibers, PBO fibers, high-strength polyethylene fibers, alumina fibers, and silicon carbide fibers. The form and arrangement of the reinforcing fibers can be appropriately selected from, for example, woven fabrics, nonwoven fabrics, mats, knits, braided cords, unidirectional strands, rovings, and chopped fibers. Preforms (layers of woven fabric base fabrics made of reinforcing fibers, or fabrics sewn together with stitching threads, or fiber structures such as three-dimensional woven fabrics and braided fabrics) can also be used as the form of the reinforcing fibers.

[0253] Generally known methods can be used as appropriate for producing fiber-reinforced composite materials. Specific examples include liquid composite molding, resin film infusion, filament winding, hand layup, and pultrusion. Among these, resin transfer molding, which is one type of liquid composite molding, allows materials other than preforms, such as metal plates, foam cores, and honeycomb cores, to be placed in the mold beforehand, making it suitable for a variety of applications. Therefore, it is preferably used for mass-producing composite materials with relatively complex shapes in a short period of time.

[0254] [Adhesive] The adhesive includes the resin composition of this embodiment. A generally known method can be appropriately applied as a method for producing the adhesive. For example, such a production method includes a method of mixing the resin composition with various known additives or solvents generally used in adhesive applications using a known mixer. Note that, when mixing, a generally known method can be appropriately applied as a method for adding the cyanate ester compound, various additives, and solvent.

[0255] [Resin Composite Sheet] The resin composite sheet includes a support and a resin layer disposed on the surface of the support, the resin layer containing the resin composition of this embodiment. The resin composite sheet can also be obtained by applying a solution of the resin composition of this embodiment dissolved in a solvent to a support and drying the resulting solution. Examples of the support include polyethylene film, polypropylene film, polycarbonate film, polyethylene terephthalate film, ethylene tetrafluoroethylene copolymer film, and release films obtained by applying a release agent to the surface of these films; organic film substrates such as polyimide film; conductive foils such as copper foil and aluminum foil; glass plates, SUS plates, and FRP plates. Examples of application methods include applying a solution of the resin composition dissolved in a solvent to the support using a bar coater, die coater, doctor blade, baker applicator, or the like. After drying, the support can be peeled or etched from the laminate sheet to form a single-layer sheet (resin sheet). In addition, a single-layer sheet (resin sheet) can also be obtained without using a support by supplying a solution of the resin composition dissolved in a solvent into a mold having a sheet-shaped cavity and drying it to form it into a sheet.

[0256] In producing a single-layer or laminate sheet, the drying conditions for removing the solvent are preferably a temperature of 20° C. or higher and 200° C. or lower for 1 minute or longer and 90 minutes or shorter, since low temperatures tend to leave the solvent in the resin composition, and high temperatures tend to accelerate curing of the resin composition. The thickness of the resin layer of the single-layer or laminate sheet can be adjusted by the concentration of the resin composition solution and the coating thickness, but generally, a thicker coating thickness tends to leave the solvent during drying, so the thickness is preferably 0.1 μm or longer and 500 μm or shorter.

[0257] [Film] The film is formed by molding the resin composition into a sheet. Such a film can be used, for example, as a build-up film or a dry film solder resist. Examples of methods for producing the film include using a peelable plastic film as a substrate, applying a solution of the resin composition dissolved in a solvent to the plastic film, and drying the applied solution. The solvent can be dried by heating at a temperature of 20°C to 150°C for 1 minute to 90 minutes. The film can be used in an uncured state, in which the solvent has simply been dried from the resin composition, or, if necessary, in a semi-cured (B-staged) state.

[0258] [Printed Wiring Board] The printed wiring board includes an insulating layer and a conductor layer formed on the surface of the insulating layer, and the insulating layer includes a resin composition. That is, it is preferable that the insulating layer is composed of an insulating layer including the resin composition of the present embodiment.

[0259] Metal foil-clad laminates can be suitably used as printed wiring boards. Printed wiring boards can be manufactured according to conventional methods. An example of a method for manufacturing a printed wiring board is shown below. First, a metal foil-clad laminate, such as a copper-clad laminate, is prepared. Next, the surface of the metal foil-clad laminate is etched to form an inner layer circuit, thereby producing an inner layer substrate. The inner layer circuit surface of this inner layer substrate is then subjected to a surface treatment to enhance adhesive strength, if necessary. A required number of prepregs are then stacked on the inner layer circuit surface, and a metal foil for an outer layer circuit is further laminated on the outer surface, followed by heating and pressurization to form an integral mold. In this way, a multilayer laminate is manufactured, in which an insulating layer consisting of a substrate and a cured resin composition is formed between the inner layer circuit and the metal foil for the outer layer circuit. Next, the multilayer laminate is drilled for through holes or via holes, and a plated metal film that connects the inner layer circuit and the metal foil for the outer layer circuit is formed on the wall surface of the hole, providing electrical continuity between the inner layer circuit and the metal foil for the outer layer circuit. The metal foil for the outer layer circuit is then etched to form the outer layer circuit, thereby manufacturing a printed wiring board.

[0260] The present invention will be described in more detail below with reference to examples, although the present invention is not particularly limited to the following examples.

[0261] [Calculation and Measurement Methods] (1) Hydrogen Halide Contamination Rate (Hydrogen Halide Contamination Rate) In the Examples and Comparative Examples, the hydrochloric acid contamination rate (%) in the organic phase (dichloromethane phase) in Solution 3 after the separation step relative to the amount of 1-naphthol aralkyl resin used was calculated as follows.

[0262] That is, the amount of hydrochloric acid in the aqueous phase of reaction solution 1 after the reaction (before separation) (molar ratio A relative to 1 mol of hydroxy groups of the 1-naphthol aralkyl resin) was defined by formula (i) where B (molar ratio) is the total amount of triethylamine used in the entire system (main reaction) (molar ratio relative to 1 mol of hydroxy groups of the 1-naphthol aralkyl resin), 1.2 molar ratio is the amount of triethylamine used for cyanation relative to 1 mol of hydroxy groups of the 1-naphthol aralkyl resin, and C (molar ratio) is the amount of hydrochloric acid charged before the reaction (molar ratio relative to 1 mol of hydroxy groups of the 1-naphthol aralkyl resin). A=C-(B-1.2)...(i)

[0263] Cyanation proceeds in the dichloromethane phase by a desalting reaction of the hydroxy groups of the 1-naphthol aralkyl resin with cyanogen chloride and triethylamine, and a 1.2 molar ratio of triethylamine is required per 1 mol of hydroxy groups of the 1-naphthol aralkyl resin. Meanwhile, in the aqueous phase, a neutralization reaction between hydrochloric acid and triethylamine also proceeds, so all of the triethylamine used in the entire system (main reaction) is consumed in both the cyanation reaction and the neutralization reaction. Therefore, the amount of triethylamine consumed in the neutralization reaction with hydrochloric acid in the aqueous phase (molar ratio relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) is the total amount of triethylamine used in the entire system (main reaction) (B-1.2), and the amount of hydrochloric acid remaining after the neutralization reaction, i.e., the amount A of hydrochloric acid in the aqueous phase in reaction solution 1 after the reaction (before separation) (molar ratio relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin), can be defined as C-(B-1.2), which is formula (i).

[0264] The hydrochloric acid concentration D (%) in the aqueous phase of reaction solution 1 after the reaction (before separation) was defined by formula (ii) where E (g) is the amount of 1-naphthol aralkyl resin used, F (g / eq.) is the hydroxy group equivalent of the 1-naphthol aralkyl resin, and G (g) is the mass of the aqueous phase in reaction solution 1 after the reaction (before separation): D = [[{A × (E / F)} × 36.46] / G] × 100 (ii)

[0265] The amount (mol) of hydroxy groups used in the entire system (main reaction) is expressed as (E / F), so the amount (mol) of hydrochloric acid in the aqueous phase of Reaction Solution 1 after the reaction (before separation) is {A × (E / F)}. Multiplying this by the molecular weight of hydrochloric acid, 36.46 (g / mol), [{A × (E / F)} × 36.46], gives the amount (g) of hydrochloric acid in the aqueous phase of Reaction Solution 1 after the reaction (before separation). This equation is divided by the mass G (g) of the aqueous phase of Reaction Solution 1 after the reaction (before separation) to give the percentage (%), [[{A × (E / F)} × 36.46] / G] × 100, which can be defined as equation (ii), which represents the hydrochloric acid concentration D (%) in the aqueous phase of Reaction Solution 1 after the reaction (before separation).

[0266] The post-treatment of reaction solution 1 is as follows. Reaction solution 1 is allowed to stand, and the lower organic phase (dichloromethane phase) is removed from the bottom of the vessel and transferred to another vessel, thereby separating reaction solution 1 into aqueous phase 1 and dichloromethane phase 1 (liquid separation 1). At this time, a certain amount of the upper aqueous phase 1 of reaction solution 1 is mixed with dichloromethane phase 1 of reaction solution 1, thereby obtaining solution 1 having aqueous phase 2 and dichloromethane phase 2 resulting from the mixing of aqueous phase 1. A certain amount of water is further added to aqueous phase 2 of solution 1, and the mixture is stirred and mixed to dilute the hydrochloric acid in aqueous phase 2, thereby obtaining solution 2 having aqueous phase 3 and dichloromethane phase 3 resulting from the dilution of aqueous phase 2. Solution 2 is allowed to stand, and the lower dichloromethane phase is removed from the bottom of the vessel and transferred to another vessel, thereby separating solution 2 (liquid separation 2). In this case, a certain amount of the upper aqueous phase 3 of the solution 2 is mixed with the dichloromethane phase 3 of the solution 2 to obtain a solution 3 having an aqueous phase 4 and a dichloromethane phase 4 resulting from the mixing of the aqueous phase 3.

[0267] The contamination rate H (%) of hydrochloric acid in dichloromethane phase 4 in Solution 3 after Separation 2 relative to the amount of 1-naphthol aralkyl resin used was defined by the following formula (iii), where I is the dilution ratio of aqueous phase 3 in Solution 2 after dilution of Solution 1 with aqueous phase 2, and J (g) is the contamination amount of aqueous phase 3, the upper phase of Solution 2 in Separation 2 [corresponding to aqueous phase 4 in Solution 3]: H=D / I×J / E (iii)

[0268] After the cyanation reaction was completed, reaction solution 1 was allowed to stand, and the lower dichloromethane phase of reaction solution 1 was drained from the bottom of the vessel. When transferring to another vessel, j (g) of the upper aqueous phase 1 of reaction solution 1 was mixed in. K (g) of water was further added to aqueous phase 2 of solution 1 after separation 1, and the mixture was stirred and mixed to dilute the hydrochloric acid in aqueous phase 2. The dilution ratio I of aqueous phase 3 in solution 2 after dilution of solution 1 with aqueous phase 2 was defined by the following formula (iv). Note that in Comparative Examples 1 to 3, K (g) of water was not added to aqueous phase 2, so K was set to 0 (g). I = {j + K} / j (iv) Note that the amount j (g) of aqueous phase 1 mixed in the upper phase of reaction solution 1 [corresponding to aqueous phase 2 in solution 1] is equal to the amount J (g) of aqueous phase 3 mixed in the upper phase of solution 2 in separation 2 [corresponding to aqueous phase 4 in solution 3].

[0269] (2) Content of Compound Having One Carbamate Group The content (area %) of compounds having one carbamate group (monocarbamate) in the cyanate ester compounds obtained in the Examples and Comparative Examples was measured as follows. That is, 0.3 g of a 2-butanone solution containing 50% by mass of cyanate ester compound was dissolved in 100 g of tetrahydrofuran (solvent) to obtain a solution. 2.0 μL of this solution was injected into a high-performance liquid chromatograph (High-Performance Liquid Chromatograph Chromaster (trade name) manufactured by Hitachi High-Tech Corporation) for analysis. The column used was a TSKgel ODS-120T (length 25 cm × inner diameter 4.6 mm) manufactured by Tosoh Corporation, and the mobile phase was acetonitrile / water (80 / 20 volume ratio). The flow rate was 1.0 mL / min, the detection wavelength was 274 nm, and the column temperature was 35°C. The content of the compound having one carbamate group (monocarbamate) in the cyanate ester compound was calculated from the peak area value of the peak with a retention time (RT) of 5.6 minutes.

[0270] (3) Peak Top Temperature The exothermic peak temperature (peak top temperature, °C) of the cyanate ester compounds obtained in the examples and comparative examples was measured as follows. First, as a pretreatment, 5.0 g of a 2-butanone solution containing 50% by mass of the cyanate ester compound was concentrated under reduced pressure, and then further concentrated to dryness at 70°C for 1 hour to obtain 2.7 g of a cyanate ester compound. The peak top temperature (unit: °C) was measured by observing the exothermic behavior of the obtained cyanate ester compound using a differential scanning calorimeter (DSC7020 (trade name), manufactured by SII NanoTechnology Inc.) under measurement conditions of an initial temperature of 40°C, an end temperature of 380°C, and a heating rate of 3.0°C / min. Note that a higher peak top temperature indicates easier control of the polymerization reaction.

[0271] Example 1 700 g (hydroxy group equivalent: 233 g / eq., hydroxy group equivalent: 3.01 mol) of 1-naphthol aralkyl resin (SN495V, product name, manufactured by Nippon Steel Chemical & Material Co., Ltd.) as a hydroxy-substituted aromatic compound and 406.0 g (4.01 mol, an amount corresponding to 1.35 mol per mol of hydroxy groups in the 1-naphthol aralkyl resin) of triethylamine as a basic compound were dissolved in 4200 g of dichloromethane as an organic solvent while maintaining the solution temperature at 0°C, and the resulting solution was designated solution A.

[0272] A mixed liquid (cyanogen halide solution) of 295.6 g (4.81 mol, 1.60 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) of cyanogen chloride as the cyanogen halide, 689.7 g of dichloromethane as an organic solvent, 487.0 g (4.81 mol, 1.60 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) of 36% hydrochloric acid as the hydrogen halide, and 3019.6 g of water was stirred and kept at a liquid temperature of −5 to 1° C., and into this mixed liquid, solution A obtained above was added over 70 minutes to obtain solution B. Thereafter, while maintaining the liquid temperature at -5 to 1°C, solution B was further stirred for 5 minutes, and then, while maintaining the liquid temperature at -5 to 1°C, solution C, prepared by dissolving 273.7 g (2.71 mol, 0.90 mol per mol of hydroxy groups in the 1-naphthol aralkyl resin) of triethylamine as a basic compound in 273.7 g of dichloromethane as an organic solvent, was poured into solution B over 15 minutes to obtain solution D. Thereafter, while maintaining the liquid temperature at -5 to 1°C, solution D was further stirred for 30 minutes to complete the reaction, thereby obtaining reaction solution 1. The pH of the aqueous phase (upper phase) of reaction solution 1 was measured using a pH meter (IQ Scientific Instruments, IQ150 (trade name)) and was found to be 0.9.

[0273] Thereafter, reaction solution 1 was allowed to stand, and 6,055 g of the lower organic phase (dichloromethane phase) was removed from the bottom of the kettle and transferred to another kettle, thereby separating reaction solution 1 into aqueous phase 1 and dichloromethane phase 1 (liquid separation 1). At this time, 605 g of the upper aqueous phase 1 of reaction solution 1 was mixed with dichloromethane phase 1 of reaction solution 1, yielding solution 1 having aqueous phase 2 and dichloromethane phase 2 resulting from the mixing of aqueous phase 1. An additional 1,000 g of water was added to aqueous phase 2 of solution 1, and the mixture was stirred and mixed to dilute the hydrochloric acid in aqueous phase 2, yielding solution 2 having aqueous phase 3 and dichloromethane phase 3 resulting from the dilution of aqueous phase 2. Solution 2 was allowed to stand, and 6,055 g of the lower dichloromethane phase was removed from the bottom of the kettle and transferred to another kettle, thereby separating solution 2 (liquid separation 2). At this time, 605 g of the upper aqueous phase 3 of Solution 2 was mixed with the dichloromethane phase 3 of Solution 2 to obtain Solution 3 having an aqueous phase 4 and a dichloromethane phase 4 resulting from the mixing of the aqueous phase 3.

[0274] The mass G of the aqueous phase in reaction solution 1 after the reaction (before separation) was 4,739 g, and the concentration D of hydrochloric acid in the aqueous phase in reaction solution 1 after the reaction (before separation) was 1.27%. The amount j of the mixed aqueous phase in separation 1 was 605 g, and the dilution ratio I of aqueous phase 3 in solution 2 after dilution of solution 1 with aqueous phase 2 was 2.7. The amount J of mixed aqueous phase 3 in the upper phase of solution 2 (corresponding to aqueous phase 4 in solution 3) was 605 g. The rate H of hydrochloric acid contamination in dichloromethane phase 4 in solution 3 after separation 2, relative to the amount of 1-naphthol aralkyl resin used, was 0.41%.

[0275] The resulting solution 3 was heated and distilled until the bottom liquid temperature reached a maximum of 46°C, at which point cyanogen chloride and dichloromethane were distilled off. Then, fresh dichloromethane equivalent to the distilled mass was added to the substrate, yielding solution 4. Solution 4 was then washed five times with 2000 g of water to yield solution 5. The electrical conductivity of the wastewater from the fifth water wash was measured using a portable EC meter (HI8733N, product name, manufactured by Hanna Instruments) and found to be 10 μS / cm. This electrical conductivity value confirmed that ionic compounds had been sufficiently removed by washing with water, and that the content of ionic compounds in solution 5 was sufficiently low.

[0276] The dichloromethane phase of Solution 5 was concentrated under reduced pressure, and solvent substitution with 2-butanone solution was repeated five times to obtain 1,442 g of a 2-butanone solution containing 50 mass % of the target cyanate ester compound (compound represented by formula (17)). The content of the compound having one carbamate group (compound represented by formula (18)) in the obtained cyanate ester compound was 0.09 area % in terms of HPLC area percentage, and the peak top temperature was 277°C. These results are shown in Table 1.

[0277] Example 2 700 g (hydroxy group equivalent: 236 g / eq., hydroxy group equivalent: 2.97 mol) of 1-naphthol aralkyl resin (SN495V, product name, manufactured by Nippon Steel Chemical & Material Co., Ltd.) as a hydroxy-substituted aromatic compound and 451.5 g (4.46 mol, an amount corresponding to 1.50 mol per mol of hydroxy groups in the 1-naphthol aralkyl resin) of triethylamine as a basic compound were dissolved in 4200 g of dichloromethane as an organic solvent while maintaining the solution temperature at 0° C., and the resulting solution was designated solution A.

[0278] A mixed liquid (cyanogen halide solution) of 256.0 g (4.16 mol, 1.40 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) of cyanogen chloride as the cyanogen halide, 597.4 g of dichloromethane as an organic solvent, 421.8 g (4.16 mol, 1.40 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) of 36% hydrochloric acid as the hydrogen halide, and 2,615.2 g of water was stirred and kept at a liquid temperature of −2 to −0.5° C., and into this mixed liquid, solution A obtained above was added over 71 minutes, thereby obtaining solution B. Thereafter, while maintaining the liquid temperature at -2 to -0.5°C, solution B was further stirred for 5 minutes, and then, while maintaining the liquid temperature at -2 to -0.5°C, solution C, prepared by dissolving 150.5 g of triethylamine (1.49 mol, 0.50 mol per mol of hydroxy groups in the 1-naphthol aralkyl resin) as a basic compound in 150.5 g of dichloromethane as an organic solvent, was poured into solution B over 12 minutes to obtain solution D. Thereafter, while maintaining the liquid temperature at -2 to -0.5°C, solution D was further stirred for 30 minutes to complete the reaction, thereby obtaining reaction solution 1. The pH of the aqueous phase (upper phase) of reaction solution 1 was measured using a pH meter (IQ Scientific Instruments IQ150 (trade name)) and was found to be 0.9.

[0279] Thereafter, reaction solution 1 was allowed to stand, and 5,940 g of the lower organic phase (dichloromethane phase) was removed from the bottom of the kettle and transferred to another kettle, thereby separating reaction solution 1 into aqueous phase 1 and dichloromethane phase 1 (liquid separation 1). At this time, 300 g of the upper aqueous phase 1 of reaction solution 1 was mixed with dichloromethane phase 1 of reaction solution 1, yielding solution 1 having aqueous phase 2 and dichloromethane phase 2 resulting from the mixing of aqueous phase 1. An additional 150 g of water was added to aqueous phase 2 of solution 1, followed by stirring and mixing to dilute the hydrochloric acid in aqueous phase 2, yielding solution 2 having aqueous phase 3 and dichloromethane phase 3 resulting from the dilution of aqueous phase 2. Solution 2 was allowed to stand, and 5,940 g of the lower dichloromethane phase was removed from the bottom of the kettle and transferred to another kettle, thereby separating solution 2 (liquid separation 2). At this time, 300 g of the upper aqueous phase 3 of solution 2 was mixed with the dichloromethane phase 3 of solution 2 to obtain solution 3 having an aqueous phase 4 and a dichloromethane phase 4 resulting from the mixing of aqueous phase 3.

[0280] The mass G of the aqueous phase in reaction solution 1 after the reaction (before separation) was 3,649 g, and the concentration D of hydrochloric acid in the aqueous phase in reaction solution 1 after the reaction (before separation) was 1.78%. The amount j of the mixed aqueous phase in separation 1 was 300 g, and the dilution ratio I of aqueous phase 3 in solution 2 after dilution of solution 1 with aqueous phase 2 was 1.5. The amount J of mixed aqueous phase 3 in the upper phase of solution 2 (corresponding to aqueous phase 4 in solution 3) was 300 g. The contamination rate H of hydrochloric acid in dichloromethane phase 4 in solution 3 after separation 2 relative to the amount of 1-naphthol aralkyl resin used was 0.51%.

[0281] The resulting solution 3 was heated and distilled until the bottom liquid temperature reached a maximum of 46°C, at which point cyanogen chloride and dichloromethane were distilled off. Then, fresh dichloromethane equivalent to the distilled mass was added to the substrate, yielding solution 4. Solution 4 was then washed five times with 2000 g of water to yield solution 5. The electrical conductivity of the wastewater from the fifth water wash was measured using a portable EC meter (HI8733N, product name, manufactured by Hanna Instruments) and found to be 10 μS / cm. This electrical conductivity value confirmed that ionic compounds had been sufficiently removed by washing with water, and that the content of ionic compounds in solution 5 was sufficiently low.

[0282] The dichloromethane phase of Solution 5 was concentrated under reduced pressure, and solvent substitution with 2-butanone solution was repeated five times to obtain 1,439 g of a 2-butanone solution containing 50 mass % of the target cyanate ester compound (compound represented by formula (17)). The content of the compound having one carbamate group (compound represented by formula (18)) in the obtained cyanate ester compound was 0.16 area % in terms of HPLC area percentage, and the peak top temperature was 272°C. These results are shown in Table 1.

[0283] Example 3 700 g (hydroxy group equivalent: 236 g / eq., hydroxy group equivalent: 2.97 mol) of 1-naphthol aralkyl resin (SN495V, product name, manufactured by Nippon Steel Chemical & Material Co., Ltd.) as a hydroxy-substituted aromatic compound and 451.5 g (4.46 mol, an amount corresponding to 1.50 mol per mol of hydroxy groups in the 1-naphthol aralkyl resin) of triethylamine as a basic compound were dissolved in 4200 g of dichloromethane as an organic solvent while maintaining the solution temperature at 0° C., and the resulting solution was designated solution A.

[0284] A mixed liquid (cyanogen halide solution) of 256.0 g (4.16 mol, 1.40 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) of cyanogen chloride as the cyanogen halide, 597.4 g of dichloromethane as an organic solvent, 421.8 g (4.16 mol, 1.40 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) of 36% hydrochloric acid as the hydrogen halide, and 2,615.2 g of water was stirred and kept at a liquid temperature of −6 to −1° C., and into this mixed liquid, solution A obtained above was added over 71 minutes, thereby obtaining solution B. Thereafter, while maintaining the liquid temperature at -6 to -1°C, solution B was further stirred for 5 minutes, and then, while maintaining the liquid temperature at -6 to -1°C, solution C, prepared by dissolving 90.3 g (0.89 mol, 0.30 mol per mol of hydroxy groups in the 1-naphthol aralkyl resin) of triethylamine as a basic compound in 90.3 g of dichloromethane as an organic solvent, was poured into solution B over 16 minutes to obtain solution D. Thereafter, while maintaining the liquid temperature at -6 to -1°C, solution D was further stirred for 30 minutes to complete the reaction, thereby obtaining reaction solution 1. The pH of the aqueous phase (upper phase) of reaction solution 1 was measured using a pH meter (IQ Scientific Instruments IQ150 (trade name)) and was found to be 0.9.

[0285] Thereafter, reaction solution 1 was allowed to stand, and 6,322 g of the lower organic phase (dichloromethane phase) was removed from the bottom of the kettle and transferred to another kettle, thereby separating reaction solution 1 into aqueous phase 1 and dichloromethane phase 1 (liquid separation 1). At this time, 300 g of the upper aqueous phase 1 of reaction solution 1 was mixed with dichloromethane phase 1 of reaction solution 1, yielding solution 1 having aqueous phase 2 and dichloromethane phase 2 resulting from the mixing of aqueous phase 1. An additional 150 g of water was added to aqueous phase 2 of solution 1, and the mixture was stirred and mixed to dilute the hydrochloric acid in aqueous phase 2, yielding solution 2 having aqueous phase 3 and dichloromethane phase 3 resulting from the dilution of aqueous phase 2. Solution 2 was allowed to stand, and 6,322 g of the lower dichloromethane phase was removed from the bottom of the kettle and transferred to another kettle, thereby separating solution 2 (liquid separation 2). At this time, 300 g of the upper aqueous phase 3 of solution 2 was mixed with the dichloromethane phase 3 of solution 2 to obtain solution 3 having an aqueous phase 4 and a dichloromethane phase 4 resulting from the mixing of aqueous phase 3.

[0286] The mass G of the aqueous phase in reaction solution 1 after the reaction (before separation) was 3,575 g, and the concentration D of hydrochloric acid in the aqueous phase in reaction solution 1 after the reaction (before separation) was 2.43%. The amount j of the mixed aqueous phase in separation 1 was 300 g, and the dilution ratio I of aqueous phase 3 in solution 2 after dilution of solution 1 with aqueous phase 2 was 1.5. The amount J of mixed aqueous phase 3 in the upper phase of solution 2 (corresponding to aqueous phase 4 in solution 3) was 300 g. The contamination rate H of hydrochloric acid in dichloromethane phase 4 in solution 3 after separation 2 relative to the amount of 1-naphthol aralkyl resin used was 0.69%.

[0287] The resulting solution 3 was heated and distilled to a maximum bottom liquid temperature of 50°C to distill off cyanogen chloride and dichloromethane, and then fresh dichloromethane equivalent to the distilled mass was added to the substrate to obtain solution 4. Solution 4 was then washed five times with 2000 g of water to obtain solution 5. The electrical conductivity of the wastewater from the fifth water wash was measured using a portable EC meter (HI8733N, product name, manufactured by Hanna Instruments) and was found to be 10 μS / cm. This electrical conductivity value confirmed that ionic compounds had been sufficiently removed by washing with water and that the content of ionic compounds in solution 5 was sufficiently low.

[0288] The dichloromethane phase of Solution 5 was concentrated under reduced pressure, and solvent substitution with a 2-butanone solution was repeated five times to obtain 1,442 g of a 2-butanone solution containing 50 mass % of the target cyanate ester compound (compound represented by formula (17)). The content of the compound having one carbamate group (compound represented by formula (18)) in the obtained cyanate ester compound was 0.16 area % in terms of HPLC area percentage, and the peak top temperature was 273°C. These results are shown in Table 1.

[0289] Comparative Example 1 700 g (hydroxy group equivalent: 236 g / eq., calculated as 2.97 mol of hydroxy groups) of 1-naphthol aralkyl resin (SN495V, product name, manufactured by Nippon Steel Chemical & Material Co., Ltd.) as a hydroxy-substituted aromatic compound and 361.2 g (3.57 mol, an amount corresponding to 1.20 mol per mol of hydroxy groups in the 1-naphthol aralkyl resin) of triethylamine as a basic compound were dissolved in 4200 g of dichloromethane as an organic solvent while maintaining the solution temperature at 0° C., and the resulting solution was designated solution A.

[0290] A mixed liquid (cyanogen halide solution) of 292.6 g (4.76 mol, 1.60 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) of cyanogen chloride as the cyanogen halide, 682.7 g of dichloromethane as an organic solvent, 482.07 g (4.76 mol, 1.60 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) of 36% hydrochloric acid as the hydrogen halide, and 2,988.8 g of water was stirred and kept at a liquid temperature of −4 to −1° C., and into this mixed liquid, solution A obtained above was added over 72 minutes, thereby obtaining solution B. Thereafter, while maintaining the liquid temperature at -4 to -1°C, solution B was further stirred for 5 minutes, and then, while maintaining the liquid temperature at -4 to -1°C, solution C, prepared by dissolving 120.4 g of triethylamine (1.19 mol, 0.40 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) as a basic compound in 120.4 g of dichloromethane as an organic solvent, was poured into solution B over 12 minutes to obtain solution D. Thereafter, while maintaining the liquid temperature at -4 to -1°C, solution D was further stirred for 30 minutes to complete the reaction, thereby obtaining reaction solution 1. The pH of the aqueous phase (upper phase) of reaction solution 1 was measured using a pH meter (IQ Scientific Instruments IQ150 (trade name)) and was found to be 0.3.

[0291] Thereafter, reaction solution 1 was allowed to stand, and 5,557.6 g of the lower organic phase (dichloromethane phase) was removed from the bottom of the kettle and transferred to another kettle, thereby separating reaction solution 1 into aqueous phase 1 and dichloromethane phase 1 (liquid separation 1). At this time, 314 g of the upper aqueous phase 1 of reaction solution 1 was mixed with dichloromethane phase 1 of reaction solution 1, yielding solution 1 having aqueous phase 2 and dichloromethane phase 2 resulting from the mixing of aqueous phase 1. Water was not added to aqueous phase 2 of solution 1, and the two-phase mixture was transferred to another kettle, yielding solution 2 having aqueous phase 3 and dichloromethane phase 3 (i.e., corresponding to solution 1 having aqueous phase 2 and dichloromethane phase 2). Solution 2 was allowed to stand, and 5,557.6 g of the lower dichloromethane phase was removed from the bottom of the kettle and transferred to another kettle, thereby separating solution 2 (liquid separation 2). In this case, 314 g of the upper aqueous phase 3 of Solution 2 was mixed with the dichloromethane phase 3 of Solution 2 to obtain Solution 3 having an aqueous phase 4 and a dichloromethane phase 4 resulting from the mixing of the aqueous phase 3 (i.e., corresponding to Solution 1 having an aqueous phase 2 and a dichloromethane phase 2).

[0292] The mass G of the aqueous phase in reaction solution 1 after the reaction (before separation) was 3,948 g, and the concentration D of hydrochloric acid in the aqueous phase in reaction solution 1 after the reaction (before separation) was 3.3%. The amount j of the mixed aqueous phase in separation 1 was 314 g, and the dilution ratio I of aqueous phase 3 in solution 2 after dilution of solution 1 with aqueous phase 2 was 1.0. The amount J of mixed aqueous phase 3 in the upper phase of solution 2 (corresponding to aqueous phase 4 in solution 3) was 314 g. The rate H of hydrochloric acid contamination in dichloromethane phase 4 in solution 3 after separation 2, relative to the amount of 1-naphthol aralkyl resin used, was 1.48%.

[0293] The resulting solution 3 was heated and distilled to a maximum bottom liquid temperature of 55°C to distill off cyanogen chloride and dichloromethane, and then fresh dichloromethane equivalent to the distilled mass was added to the substrate to obtain solution 4. Solution 4 was then washed six times with 2000 g of water to obtain solution 5. The electrical conductivity of the wastewater from the sixth water wash was measured using a portable EC meter (HI8733N, product name, manufactured by Hanna Instruments) and found to be 10 μS / cm. This electrical conductivity value confirmed that ionic compounds had been sufficiently removed by washing with water and that the content of ionic compounds in solution 5 was sufficiently low.

[0294] The dichloromethane phase of Solution 5 was concentrated under reduced pressure, and solvent substitution with a 2-butanone solution was repeated five times to obtain 1,439 g of a 2-butanone solution containing 50 mass % of the target cyanate ester compound (compound represented by formula (17)). The content of the compound having one carbamate group (compound represented by formula (18)) in the obtained cyanate ester compound was 3.40 area % in terms of HPLC area percentage, and the peak top temperature was 250°C. These results are shown in Table 1.

[0295] Comparative Example 2 700 g (hydroxy group equivalent: 236 g / eq., calculated as 2.97 mol of hydroxy groups) of 1-naphthol aralkyl resin (SN495V, product name, manufactured by Nippon Steel Chemical & Material Co., Ltd.) as a hydroxy-substituted aromatic compound and 361.2 g (3.57 mol, an amount corresponding to 1.20 mol per mol of hydroxy groups in the 1-naphthol aralkyl resin) of triethylamine as a basic compound were dissolved in 4200 g of dichloromethane as an organic solvent while maintaining the solution temperature at 0° C., and the resulting solution was designated solution A.

[0296] A mixed liquid (cyanogen halide solution) of 274.3 g (4.46 mol, 1.50 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) of cyanogen chloride as the cyanogen halide, 640.0 g of dichloromethane as an organic solvent, 451.9 g (4.46 mol, 1.50 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) of 36% hydrochloric acid as the hydrogen halide, and 2,802.0 g of water was stirred and kept at a liquid temperature of −2 to −0.5° C., and into this mixed liquid, solution A obtained above was added over 70 minutes to obtain solution B. Thereafter, while maintaining the liquid temperature at -2 to -0.5°C, solution B was further stirred for 5 minutes, and then, while maintaining the liquid temperature at -2 to -0.5°C, solution C, prepared by dissolving 167.2 g (1.65 mol, 0.55 mol per mol of hydroxy groups in the 1-naphthol aralkyl resin) of triethylamine as a basic compound in 167.2 g of dichloromethane as an organic solvent, was poured into solution B over 12 minutes to obtain solution D. Thereafter, while maintaining the liquid temperature at -2 to -0.5°C, solution D was further stirred for 30 minutes to complete the reaction, thereby obtaining reaction solution 1. The pH of the aqueous phase (upper phase) of reaction solution 1 was measured using a pH meter (IQ Scientific Instruments IQ150 (trade name)) and was found to be 0.2.

[0297] Thereafter, reaction solution 1 was allowed to stand, and 5,571.5 g of the lower organic phase (dichloromethane phase) was removed from the bottom of the kettle and transferred to another kettle, thereby separating reaction solution 1 into aqueous phase 1 and dichloromethane phase 1 (liquid separation 1). At this time, 314 g of the upper aqueous phase 1 of reaction solution 1 was mixed with dichloromethane phase 1 of reaction solution 1, yielding solution 1 having aqueous phase 2 and dichloromethane phase 2 resulting from the mixing of aqueous phase 1. Water was not added to aqueous phase 2 of solution 1, and the two-phase mixture was transferred to another kettle, yielding solution 2 having aqueous phase 3 and dichloromethane phase 3 (i.e., corresponding to solution 1 having aqueous phase 2 and dichloromethane phase 2). Solution 2 was allowed to stand, and 5,571.5 g of the lower dichloromethane phase was removed from the bottom of the kettle and transferred to another kettle, thereby separating solution 2 (liquid separation 2). In this case, 314 g of the upper aqueous phase 3 of Solution 2 was mixed with the dichloromethane phase 3 of Solution 2 to obtain Solution 3 having an aqueous phase 4 and a dichloromethane phase 4 resulting from the mixing of the aqueous phase 3 (i.e., corresponding to Solution 1 having an aqueous phase 2 and a dichloromethane phase 2).

[0298] The mass G of the aqueous phase in reaction solution 1 after the reaction (before separation) was 3,920.5 g, and the concentration D of hydrochloric acid in the aqueous phase in reaction solution 1 after the reaction (before separation) was 2.77%. The amount j of the mixed aqueous phase in separation 1 was 314 g, and the dilution ratio I of aqueous phase 3 in solution 2 after dilution of solution 1 with aqueous phase 2 was 1.0. The amount J of mixed aqueous phase 3 in the upper phase of solution 2 (corresponding to aqueous phase 4 in solution 3) was 314 g. The rate H of hydrochloric acid contamination in dichloromethane phase 4 in solution 3 after separation 2, relative to the amount of 1-naphthol aralkyl resin used, was 1.24%.

[0299] The resulting solution 3 was heated and distilled to a maximum bottom liquid temperature of 55°C to distill off cyanogen chloride and dichloromethane, and then fresh dichloromethane equivalent to the distilled mass was added to the substrate to obtain solution 4. Solution 4 was then washed six times with 2000 g of water to obtain solution 5. The electrical conductivity of the wastewater from the sixth water wash was measured using a portable EC meter (HI8733N, product name, manufactured by Hanna Instruments) and found to be 10 μS / cm. This electrical conductivity value confirmed that ionic compounds had been sufficiently removed by washing with water and that the content of ionic compounds in solution 5 was sufficiently low.

[0300] The dichloromethane phase of Solution 5 was concentrated under reduced pressure, and solvent substitution with 2-butanone solution was repeated five times to obtain 1,440 g of a 2-butanone solution containing 50 mass % of the target cyanate ester compound (compound represented by formula (17)). The content of the compound having one carbamate group (compound represented by formula (18)) in the obtained cyanate ester compound was 2.50 area % in terms of HPLC area percentage, and the peak top temperature was 256°C. These results are shown in Table 1.

[0301] Comparative Example 3 700 g (hydroxy group equivalent: 236 g / eq., hydroxy group equivalent: 2.97 mol) of 1-naphthol aralkyl resin (SN495V, product name, manufactured by Nippon Steel Chemical & Material Co., Ltd.) as a hydroxy-substituted aromatic compound and 361.2 g (3.57 mol, an amount corresponding to 1.20 mol per mol of hydroxy groups in the 1-naphthol aralkyl resin) of triethylamine as a basic compound were dissolved in 4200 g of dichloromethane as an organic solvent while maintaining the solution temperature at 0° C., and the resulting solution was designated solution A.

[0302] A mixed liquid (cyanogen halide solution) of 292.6 g (4.76 mol, 1.60 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) of cyanogen chloride as the cyanogen halide, 682.7 g of dichloromethane as an organic solvent, 482.07 g (4.76 mol, 1.60 mol relative to 1 mol of hydroxy groups in the 1-naphthol aralkyl resin) of 36% hydrochloric acid as the hydrogen halide, and 2,988.8 g of water was stirred and kept at a liquid temperature of −4 to −3° C., and into this mixed liquid, solution A obtained above was added over 74 minutes, thereby obtaining solution B. Thereafter, while maintaining the liquid temperature at -4 to -3°C, solution B was further stirred for 5 minutes, and then solution C, prepared by dissolving 211.2 g (2.08 mol, 0.70 mol per mol of hydroxy groups in the 1-naphthol aralkyl resin) of triethylamine as a basic compound in 211.4 g of dichloromethane as an organic solvent, was poured into solution B over 21 minutes while maintaining the liquid temperature at -4 to -3°C, to obtain solution D. Thereafter, while maintaining the liquid temperature at -4 to -3°C, solution D was further stirred for 30 minutes to complete the reaction, thereby obtaining reaction solution 1. The pH of the aqueous phase (upper phase) of reaction solution 1 was measured using a pH meter (IQ Scientific Instruments IQ150 (trade name)) and was found to be 0.4.

[0303] Thereafter, reaction solution 1 was allowed to stand, and 5,777 g of the lower organic phase (dichloromethane phase) was removed from the bottom of the kettle and transferred to another kettle, thereby separating reaction solution 1 into aqueous phase 1 and dichloromethane phase 1 (liquid separation 1). At this time, 314 g of the upper aqueous phase of reaction solution 1 was mixed with dichloromethane phase 1 of reaction solution 1, thereby obtaining solution 1 having aqueous phase 2 and dichloromethane phase 2 resulting from the mixing of aqueous phase 1. Water was not added to aqueous phase 2 of solution 1, and the two-phase mixture was transferred to another kettle, thereby obtaining solution 2 having aqueous phase 3 and dichloromethane phase 3 (i.e., corresponding to solution 1 having aqueous phase 2 and dichloromethane phase 2). Solution 2 was allowed to stand, and 5,777 g of the lower dichloromethane phase was removed from the bottom of the kettle and transferred to another kettle, thereby separating solution 2 (liquid separation 2). In this case, 314 g of the upper aqueous phase 3 of Solution 2 was mixed with the dichloromethane phase 3 of Solution 2 to obtain Solution 3 having an aqueous phase 4 and a dichloromethane phase 4 resulting from the mixing of the aqueous phase 3 (i.e., corresponding to Solution 1 having an aqueous phase 2 and a dichloromethane phase 2).

[0304] The mass G of the aqueous phase in reaction solution 1 after the reaction (before separation) was 3,937 g, and the concentration D of hydrochloric acid in the aqueous phase in reaction solution 1 after the reaction (before separation) was 2.5%. The amount j of the mixed aqueous phase in separation 1 was 314 g, and the dilution ratio I of aqueous phase 3 in solution 2 after dilution of solution 1 with aqueous phase 2 was 1.0. The amount J of mixed aqueous phase 3 in the upper phase of solution 2 (corresponding to aqueous phase 4 in solution 3) was 314 g. The rate H of hydrochloric acid contamination in dichloromethane phase 5 in solution 3 after separation 2, relative to the amount of 1-naphthol aralkyl resin used, was 1.11%.

[0305] The resulting solution 3 was heated and distilled to a maximum bottom liquid temperature of 55°C to distill off cyanogen chloride and dichloromethane, and then fresh dichloromethane equivalent to the distilled mass was added to the substrate to obtain solution 4. Solution 4 was then washed six times with 2000 g of water to obtain solution 5. The electrical conductivity of the wastewater from the sixth water wash was measured using a portable EC meter (HI8733N, product name, manufactured by Hanna Instruments) and found to be 10 μS / cm. This electrical conductivity value confirmed that ionic compounds had been sufficiently removed by washing with water and that the content of ionic compounds in solution 5 was sufficiently low.

[0306] The dichloromethane phase of Solution 5 was concentrated under reduced pressure, and solvent substitution with 2-butanone solution was repeated five times to obtain 1,439 g of a 2-butanone solution containing 50 mass % of the target cyanate ester compound (compound represented by formula (17)). The content of the compound having one carbamate group (compound represented by formula (18)) in the obtained cyanate ester compound was 0.70 area % in terms of HPLC area percentage, and the peak top temperature was 267°C. These results are shown in Table 1.

[0307]

[0308] This application claims priority based on a Japanese patent application (Patent Application No. 2023-122193) filed with the Japan Patent Office on July 27, 2023, the contents of which are incorporated herein by reference.

[0309] The cyanate ester compound of the present invention can be suitably used for, for example, cured products, prepregs, laminates, metal foil-clad laminates, multilayer plates, sealing materials, fiber-reinforced composite materials, adhesives, resin composite sheets, films, and printed wiring boards.