Method for measuring cyanate group equivalent of cyanate ester compound

Abstract

To provide a method capable of measuring the cyanate group equivalent of a cyanate ester compound with high accuracy.SOLUTION: The present invention provides a method for measuring a cyanate group equivalent of a cyanate ester compound having a cyanate group in the molecule, the method comprising: mixing the cyanate ester compound and a secondary amine to prepare a first mixed solution; mixing the first mixed solution and a carboxylic acid anhydride to prepare a second mixed solution; and performing acid titration on the second mixed solution to measure the cyanate group equivalent of the cyanate ester compound.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for measuring the cyanate group equivalent of a cyanate ester compound.

Background Art

[0002] Cyanate ester compounds are known as thermosetting resins. The cured product obtained from a cyanate ester compound has properties such as a high glass transition temperature, low dielectric constant and dielectric tangent, and excellent electrical insulation and flame retardancy. Conventionally, cyanate ester compounds have been widely used as raw materials for various functional polymer materials such as structural composite materials, adhesives, electrical insulation materials, and electrical and electronic components.

[0003] Since the cyanate groups of a cyanate ester compound trimerize to form a triazine ring and cure, it is not necessary to consider the cyanate group equivalent when curing a cyanate ester compound alone. On the other hand, for example, when curing a thermosetting resin such as an epoxy resin and a bismaleimide resin with a cyanate ester compound, it is necessary to consider the cyanate group equivalent of the cyanate ester compound in order to adjust the blending ratio of the thermosetting resin and the cyanate ester compound. In addition, it is also necessary to consider the cyanate group equivalent when grasping the reaction characteristics of the cyanate ester compound.

[0004] As a method for measuring the cyanate group equivalent of a cyanate ester compound, for example, the method described in Patent Document 1 can be mentioned. Patent Document 1 describes that a secondary amine is reacted with the cyanate group of a cyanate ester compound to obtain an adduct, and after removing the residual secondary amine by devolatilization, the obtained adduct is subjected to acid-base titration to calculate the cyanate group equivalent.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the measurement method described in Patent Document 1, the decomposition of the adduct proceeds until titration. Further, it is difficult to remove all of the remaining secondary amines by devolatilization. Therefore, it is difficult to accurately measure the cyanate group equivalent of the cyanate ester compound by the measurement method described in Patent Document 1.

[0007] The present invention has been made in view of such problems, and an object thereof is to provide a method capable of accurately measuring the cyanate group equivalent of a cyanate ester compound.

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a method for measuring the cyanate group equivalent of a cyanate ester compound including a specific step, and have completed the present invention.

[0009] That is, the present invention is as follows.

[0010] [1] A method for measuring the cyanate group equivalent of a cyanate ester compound having a cyanate group in the molecule, comprising a step of mixing the cyanate ester compound and a secondary amine to prepare a first mixed solution, and the first mixed solution and a carboxylic anhydride And a step of preparing a second mixed solution, and a step of performing acid titration on the second mixed solution to measure the cyanate group equivalent of the cyanate ester compound.

[0011] [2] The method according to [1], wherein the secondary amine contains one or more selected from the group consisting of diethylamine, dipropylamine, dibutylamine, diisopropylamine, and diphenylamine.

[0012] [3] The method according to claim [1] or [2], wherein the cyanate ester compound contains one or more selected from the group consisting of cyanate ester compounds having one or more cyanate groups in the molecule and prepolymers thereof.

[0013] [4] The method according to any one of [1] to [3], wherein the cyanate ester compound contains a compound represented by the following formula (1) or a compound represented by the following formula (2).

[0014] [Chemical formula]

[0015] (In formula (1), each Ar1 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, a represents the number of cyanate groups bonded to Ar1, and each independently is an integer of 1 or more and 3 or less, b represents the number of Ra bonded to Ar1, and each independently represents the number obtained by subtracting (a + 2) from the number of substitutable groups of Ar1, c is an integer of 1 or more and 50 or less, 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.)

[0016] [Chemical formula]

[0017] (In formula (2), Ar2 represents an aromatic ring, and 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 the number of cyanate groups bonded to Ar2 and is an integer of 1 or more and 3 or less. e represents the number of Rb bonded to Ar2 and represents the number obtained by subtracting (d + 2) from the number of substitutable groups of Ar2.).

[0018] [5] The method according to any one of [1] to [4], wherein the carboxylic anhydride contains one or more selected from the group consisting of acetic anhydride, propionic anhydride, and benzoic anhydride.

[0019] [6] The method according to any one of [1] to [5], wherein in the step of preparing the second mixed solution, the addition amount of the carboxylic anhydride is 1.0 mol or more and 50 mol or less with respect to 1 mol of the secondary amine contained in the first mixed solution.

[0020] [7] The method according to any one of [1] to [6], wherein the acid titration is performed using an acetic acid solution of perchloric acid or a methanol solution of hydrochloric acid.

Advantages of the Invention

[0021] According to the present invention, it is possible to provide a method capable of accurately measuring the cyanate group equivalent of a cyanate ester compound.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The following present embodiment is an exemplification for explaining the present invention and is not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of its gist.

[0023] In this specification, the substituents are 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, alkyroyloxy group, aryroyloxy group, and alkylsilyl group.

[0024] [Method for Measuring Cyanate Group Equivalent] A method for measuring the cyanate group equivalent of a cyanate ester compound having a cyanate group in the molecule of the present embodiment (hereinafter, also simply referred to as "method for measuring cyanate group equivalent") includes a step of mixing a cyanate ester compound and a secondary amine to prepare a first mixed solution (hereinafter, also referred to as "step 1"), a step of mixing the first mixed solution and a carboxylic anhydride to prepare a second mixed solution (hereinafter, also referred to as "step 2"), and a step of performing acid titration on the second mixed solution to measure the cyanate group equivalent of the cyanate ester compound (hereinafter, also referred to as "step 3").

[0025] According to the present embodiment, it is possible to provide a method capable of accurately measuring the cyanate group equivalent of a cyanate ester compound. Although the reason for this is not clear, the present inventors presume as follows.

[0026] As shown in the following reaction formula, in Step 1, the cyanate group of the cyanate ester compound reacts with a secondary amine to form an amine adduct, and a first mixed solution containing the amine adduct and the unreacted secondary amine is obtained. In Step 2, the amine adduct contained in the first mixed solution reacts with a carboxylic anhydride to form a carboxylic acid derivative, and a second mixed solution containing the carboxylic acid derivative is obtained. Note that the second mixed solution also contains a by-product formed by the reaction of the unreacted secondary amine contained in the first mixed solution and the carboxylic anhydride. As the carboxylic acid derivative, for example, it is presumed that a carboxylic acid salt of a carboxylic acid adduct and an amine adduct having a structure as shown in Step 2 below is formed. In Steps 1 and 2, R1, R2, R3, R4, and R5 each represent an arbitrary organic group. R2 and R3 may be bonded to form a ring, and R4 and R5 may be bonded to form a ring. And in the present embodiment, in Step 3, the cyanate group equivalent is measured by acid titrating the carboxylic acid derivative contained in the second mixed solution.

[0027]

Chemical formula

[0028] The secondary amine used in Step 1 preferably reacts with the cyanate group of the cyanate ester compound. With a primary amine, an adduct is formed with the cyanate ester compound, but the adduct is easily decomposed at room temperature. Also, with a tertiary amine, it is difficult to react with the cyanate ester compound and no adduct is formed. Therefore, it is difficult to accurately measure the cyanate group equivalent with a primary amine and a tertiary amine. Also, even when a secondary amine is used, if the amine adduct formed is titrated to measure the cyanate group equivalent without performing Step 2, the secondary amine is also titrated simultaneously, so it is difficult to measure the cyanate group equivalent.

[0029] On the one hand, in this embodiment, the carboxylic acid derivative obtained in Step 2 is acid titrated to measure the cyanate group equivalent. The reaction between the amine adduct and the carboxylic anhydride proceeds favorably, and the resulting carboxylic acid derivative is difficult to decompose. Also, in Step 3, by-products such as those formed by the reaction of the unreacted secondary amine contained in the first mixture with the carboxylic anhydride are not acid titrated, and only the carboxylic acid derivative is selectively acid titrated. Therefore, errors are less likely to occur.

[0030] Even when a secondary amine having two or more amino groups such as a diamine is used as the secondary amine, the cyanate group of the cyanate ester compound reacts with only one amino group, and the remaining amino groups react with the carboxylic anhydride in Step 2 to form a carboxylic acid adduct. Therefore, even when a secondary amine having two or more amino groups is used, the measurement of the cyanate group equivalent is not affected.

[0031] However, the reason why the cyanate group equivalent of the cyanate ester compound can be accurately measured according to this embodiment is not limited to this.

[0032] (Step 1) The method for measuring the cyanate group equivalent includes Step 1 of mixing a cyanate ester compound and a secondary amine to prepare a first mixture. As shown in the above reaction formula, in Step 1, the cyanate group of the cyanate ester compound reacts with the secondary amine to form an amine adduct in which an amine is added to the cyanate ester compound. The amine adduct has a structure represented by the following formula (3).

[0033] [Chemical formula]

[0034] As a method for reacting a cyanate ester compound with a secondary amine, for example, a method of contacting and reacting both components by mixing and stirring the cyanate ester compound and the secondary amine in the presence of an organic solvent can be mentioned. As a specific contacting method, for example, a method of adding a secondary amine to a solution containing a cyanate ester compound and an organic solvent and mixing and stirring them can be mentioned.

[0035] In Step 1, the reaction temperature is preferably 0°C or higher and 50°C or lower, more preferably 10°C or higher and 30°C or lower. When the reaction temperature is within the above range, the cyanate group equivalent of the cyanate ester compound tends to be measured more accurately.

[0036] The reaction time is usually 5 minutes or longer and 2.0 hours or shorter, preferably 10 minutes or longer and 1.5 hours or shorter. When the reaction time is within the above range, the amine adduct tends to be obtained economically and more efficiently.

[0037] The pressure during the reaction is not particularly limited as long as the desired amine adduct can be obtained. Usually, it is under atmospheric pressure. Also, if necessary, an inert gas such as nitrogen, helium, and argon may be bubbled into the reaction system.

[0038] As a stirring method, for example, a method of stirring using a known stirrer such as a stirring blade and a stirrer can be mentioned. The stirring time may refer to the above reaction time.

[0039] As a container for the reaction, for example, a known container such as a glass container such as a flask, a bottle, and a vial can be used.

[0040] In Project 1, the mass ratio of the cyanate ester compound to the secondary amine can be appropriately determined in consideration of the mass or molecular weight of the cyanate ester compound. Usually, the mass ratio of the cyanate ester compound to the secondary amine is such that the secondary amine is 1.0 part by mass or more and 20.0 parts by mass or less with respect to 1 part by mass of the cyanate ester compound. When the mass ratio is within the above range, the cyanate group equivalent of the cyanate ester compound tends to be measured more accurately.

[0041] The cyanate ester compound will be described later.

[0042] Examples of the secondary amine include the secondary amine represented by the above reaction formula, that is, those having a structure represented by the following formula (4). The secondary amine can be used alone or in combination of two or more.

[0043]

Chemical formula

[0044] In formula (4), R2 and R3 each represent an arbitrary organic group. Also, R2 and R3 may be bonded to form a ring.

[0045] Examples of the organic group include an alkyl group, a cycloalkyl group, an alkoxy group, an aryl group, an aralkyl group, an alkylcarbonyl group, an alkoxycarbonyl group, and an alkylcarbonyloxy group. These groups may have, for example, a nitrogen atom, an ether bond, and a carbonyl group that do not form the structure of a primary amine or a tertiary amine.

[0046] Examples of the secondary amine include aliphatic secondary amines such as dimethylamine, diethylamine, dipropylamine, dibutylamine, diisopropylamine, N-methylethylamine, N-methylpropylamine, N-methylisopropylamine, N-methylbutylamine, N-methylisobutylamine, N-methylcyclohexylamine, N-ethylpropylamine, N-ethylisopropylamine, N-ethylbutylamine, N-ethylisobutylamine, N-ethylcyclohexylamine, N-methylvinylamine, and N-methylallylamine; aliphatic diamines and triamines such as N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N'-dimethyltrimethylenediamine, and N,N'-diethyltrimethylenediamine; aromatic amines such as diphenylamine, N-methylbenzylamine, N-ethylbenzylamine, N-methylphenethylamine, and N-ethylphenethylamine; monoalkanolamines such as N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-isopropylethanolamine, N-butylethanolamine, and N-isobutylethanolamine; dialkanolamines such as diethanolamine, dipropanolamine, diisopropanolamine, and dibutanolamine; and cyclic amines such as pyrrolidine, piperidine, piperazine, morpholine, and thiomorpholine.

[0047] The secondary amine preferably includes a secondary monoamine, and more preferably includes one or more selected from the group consisting of diethylamine, dipropylamine, dibutylamine, diisopropylamine, and diphenylamine. When such a secondary amine is used in Step 1, the cyanate group equivalent of the cyanate ester compound tends to be measured more accurately.

[0048] The cyanate ester compound and the secondary amine can be reacted, for example, in the presence of an organic solvent. The organic solvent is not particularly limited as long as it can uniformly dissolve the cyanate ester compound and the secondary amine. Examples of such organic solvents include halogen solvents such as dichloromethane, chloroform, dichloroethane, and chlorobenzene; aprotic polar solvents such as dimethylformamide, dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, dioxane, and acetonitrile; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; cellosolve solvents such as 2-ethoxyethanol and propylene glycol monomethyl ether; aliphatic alcohol solvents such as methanol, ethanol, propanol, isopropanol, and butanol; ester solvents such as ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, isoamyl acetate, methyl methoxypropionate, methyl hydroxyisobutyrate, γ-butyrolactone, and propylene glycol monomethyl ether acetate; and aromatic hydrocarbon solvents such as toluene and xylene.

[0049] The amount of the organic solvent used is usually 10.0 parts by mass or more and 200.0 parts by mass or less per 1 part by mass of the cyanate ester compound.

[0050] The first mixed solution does not contain an acid or contains only a trace amount of an acid. Specifically, the total amount of the acid is 100 ppm or less, preferably 0 ppm, per 100 parts by mass of the first mixed solution. Examples of the acid include organic acids and inorganic acids.

[0051] (Step 2) The method for measuring the cyanate group equivalent includes Step 2 of preparing a second mixed solution by mixing the first mixed solution and a carboxylic anhydride. As shown in the above reaction formula, in Step 2, the amine adduct reacts with the carboxylic anhydride to form a carboxylic acid derivative in which a carboxylic acid is added to the amine adduct. As the carboxylic acid derivative, it is presumed that, for example, a carboxylic acid adduct and a carboxylate of the amine adduct having the structure shown in Step 2 above are formed.

[0052] As a method for reacting an amine adduct with a carboxylic anhydride, for example, a method of contacting and reacting both components by mixing and stirring an amine adduct and a carboxylic anhydride in the presence of an organic solvent can be mentioned. As a specific contacting method, a method of adding a carboxylic anhydride to a first mixed solution which is a solution containing an amine adduct and an organic solvent and mixing and stirring them can be mentioned.

[0053] In Step 2, for the reaction temperature, reaction pressure, stirring method, and container, reference may be made to Step 1 above.

[0054] The reaction time is usually 30 minutes or more and 6.0 hours or less, preferably 1.0 hour or more and 4.0 hours or less. When the reaction time is within the above range, the amine adduct tends to be obtained more economically and more efficiently.

[0055] In Step 2, the addition amount of the carboxylic anhydride is preferably 1.0 mol or more and 50.0 mol or less, more preferably 5.0 mol or more and 40.0 mol or less, still more preferably 10.0 mol or more and 30.0 mol or less with respect to 1 mol of the secondary amine contained in the first mixed solution. When the addition amount of the carboxylic anhydride is within the above range, the cyanate group equivalent of the cyanate ester compound tends to be measured more accurately.

[0056] Examples of the carboxylic anhydride include the carboxylic anhydride represented by the above reaction formula, that is, those having a structure represented by the following formula (5). The carboxylic anhydride can be used alone or in combination of two or more.

[0057]

Chemical formula

[0058] In formula (5), R4 and R5 each represent an arbitrary organic group. Also, R4 and R5 may be bonded to form a ring. As the organic group, reference may be made to the groups described in the secondary amine having the structure represented by formula (4).

[0059] Examples of the carboxylic acid anhydride include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, isobutyric anhydride, butyric anhydride, 2-methylbutyric anhydride, pivalic anhydride, isovaleric anhydride, valeric anhydride, 2-methylvaleric anhydride, 3-methylvaleric anhydride, 4-methylvaleric anhydride, hexanoic anhydride, 2-methylhexanoic anhydride, 3-methylhexanoic anhydride, 4-methylhexanoic anhydride, 5-methylhexanoic anhydride, heptanoic anhydride, 2-methylheptanoic anhydride, 3-methylheptanoic anhydride, 4-methylheptanoic anhydride, 5-methylheptanoic anhydride, 6-methylheptanoic anhydride, 3-phenylpropionic anhydride, phenylacetic anhydride, methacrylic anhydride, acrylic anhydride, trichloroacetic anhydride, trifluoroacetic anhydride, tetrahydrophthalic anhydride, succinic anhydride, maleic anhydride, itaconic anhydride, and glutaric anhydride; aromatic carboxylic acid anhydrides such as benzoic anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, and naphthalic anhydride; and sulfocarboxylic acid anhydrides such as 2-sulfobenzoic anhydride.

[0060] The carboxylic acid anhydride preferably contains one or more selected from the group consisting of aliphatic carboxylic acid anhydrides and aromatic carboxylic acid anhydrides, and more preferably contains one or more selected from the group consisting of acetic anhydride, propionic anhydride, and benzoic anhydride. When these carboxylic acid anhydrides are used in Step 2, the cyanate group equivalent of the cyanate ester compound tends to be measured more accurately.

[0061] In Step 2, an organic solvent may be further added to the first mixture if necessary. For the organic solvent, reference may be made to Step 1 above. The organic solvent to be added is preferably the same as the organic solvent contained in the first mixture.

[0062] (Step 3) The method for measuring the cyanate group equivalent includes the step of performing acid titration on the second mixed solution to measure the cyanate group equivalent of the cyanate ester compound. In Step 3, the cyanate group equivalent is measured by acid titrating the carboxylic acid derivative contained in the second mixed solution.

[0063] As a specific measurement method, for example, the base of the carboxylic acid derivative contained in the second mixed solution is acid titrated using an acid standard solution, and the cyanate group equivalent is calculated using the titration amount obtained at that time and the titration amount obtained from the blank test.

[0064] Acid titration can be performed, for example, using a potentiometer and a pH meter. Also, for acid titration, a colorimetric method using an indicator may be used. Since the inflection point can be measured more clearly and the cyanate group equivalent of the cyanate ester compound tends to be measured more accurately, acid titration is preferably performed using a potentiometer.

[0065] Examples of the acid standard solution include acetic acid solution of perchloric acid, sulfuric acid aqueous solution, methanol solution of hydrochloric acid, ethanol solution of hydrochloric acid, and nitric acid aqueous solution. Among them, acid titration is preferably performed using an acetic acid solution of perchloric acid or a methanol solution of hydrochloric acid as the acid standard solution. By using such an acid standard solution, the cyanate group equivalent of the cyanate ester compound tends to be measured more accurately.

[0066] In this embodiment, when an acetic acid solution of perchloric acid is used as the acid standard solution, the carboxylic acid derivative is presumed to be titrated through, for example, the following titration formula. In the titration formula, the "*" described in each chemical formula indicates the bonding site with an organic group or a hydrogen atom.

[0067]

Chemical formula

[0068] The cyanate group equivalent weight (g / mol) of the cyanate ester compound can be calculated, for example, using the following formula (6). Cyanate group equivalent weight (g / mol) = (mass of cyanate ester compound (g) × 1000) / ((T1 - T0) (mL) × concentration of acid standard solution (mol / L) × factor of acid standard solution) … (6) In formula (6), T1 represents the titration volume (mL) at the end point when acid titration is performed using the acid standard solution. Also, T0 represents the titration volume (mL) obtained from a blank test not containing the cyanate ester compound. The factor of the acid standard solution means the correction coefficient (f) of the acid standard solution used for titration.

[0069] As the method of acid titration, a known method can be adopted. As such a method, for example, reference may be made to JIS K7237:1995 (Method for testing total amine value of amine-based curing agents for epoxy resins) and ASTM D2896 (Potentiometric perchloric acid titration). Also, for the specific acid titration method, reference may be made to the examples.

[0070] 〔Cyanate Ester Compound〕 Since the cyanate group equivalent weight of the cyanate ester compound can be measured more accurately, the cyanate ester compound preferably contains one or more selected from the group consisting of cyanate ester compounds having one or more cyanate groups in the molecule and prepolymers thereof.

[0071] A part of the cyanate ester compound may be oligomerized into trimers or pentamers in advance. Examples of the prepolymer include those having a mass average molecular weight in the range of 500 or more and 8,000 or less in terms of polystyrene by the gel permeation chromatography (GPC) method. The prepolymer can be prepared, for example, using the method described in JP-A-2000-191776.

[0072] Since the cyanate group equivalent of the cyanate ester compound can be measured more accurately, the cyanate ester compound more preferably contains a compound represented by the following formula (1) or a compound represented by the following formula (2), and more preferably contains a compound represented by the formula (1).

[0073] (Compound represented by formula (1)) The compound represented by formula (1) is shown below.

[0074] [Chemical formula]

[0075] In formula (1), each Ar1 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, a represents the number of cyanate groups bonded to Ar1, and each independently is an integer of 1 or more and 3 or less, b represents the number of Ra bonded to Ar1, and each independently represents the number obtained by subtracting (a + 2) from the number of substitutable groups of Ar1, c is an integer of 1 or more and 50 or less, 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. Each group in formula (1) may have a substituent.

[0076] In formula (1), each Ar1 independently represents an aromatic ring. Examples of the aromatic ring represented by Ar1 include a phenyl group and a naphthyl group. Since a cyanate ester compound capable of measuring the cyanate group equivalent more accurately can be obtained, Ar1 is preferably a phenyl group.

[0077] 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. Since a cyanate ester compound capable of more accurately measuring the cyanate group equivalent can be obtained, Ra is preferably a hydrogen atom or an alkenyl group having 2 to 6 carbon atoms.

[0078] Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-pentyl group, a neopentyl group, an n-hexyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. The alkyl group may be linear, branched, or cyclic.

[0079] Examples of the alkenyl group having 2 to 6 carbon atoms include a vinyl group, an allyl group, a butenyl group, a pentenyl group, and a hexenyl group. Since a cyanate ester compound capable of more accurately measuring the cyanate group equivalent can be obtained, the alkenyl group having 2 to 6 carbon atoms is preferably an alkenyl group having 2 to 5 carbon atoms. The alkenyl group may be linear, branched, or cyclic.

[0080] Examples of the aryl group having 6 to 20 carbon atoms include a phenyl group and a naphthyl group.

[0081] 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.

[0082] a represents the number of cyanate groups bonded to Ar1, and each independently is an integer of 1 to 3. Since a cyanate ester compound capable of more accurately measuring the cyanate group equivalent can be obtained, a is preferably an integer of 1 to 2, more preferably 1.

[0083] b represents the number of bonds of Ra to Ar1, and each independently represents a number obtained by subtracting (a + 2) from the number of substitutable positions of Ar1.

[0084] c is an integer of 1 or more and 50 or less. Since a cyanate ester compound capable of more accurately measuring the cyanate group equivalent can be obtained, 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 still more preferably 1.

[0085] X each 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 (-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 (-SO2-), a divalent sulfur atom or a divalent oxygen atom.

[0086] Examples of the divalent organic group having 1 to 50 carbon atoms in which a hydrogen atom may be substituted with a heteroatom include a linking group selected from the group consisting of divalent groups represented by formulas (7) to (18).

[0087] Since a cyanate ester compound capable of more accurately measuring the cyanate group equivalent can be obtained, X in the compound represented by formula (1) each independently the following formula (7):

[0088]

Chemical formula

[0089] (In formula (7), each Ar3 independently represents an aromatic ring, each of Rc, Rd, Rg, and Rh independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, each of Re and Rf 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, and f represents an integer of 0 or more and 5 or less.) A divalent organic group having 1 to 50 carbon atoms represented by The following formula (8):

[0090]

Chemical formula

[0091] (In formula (8), each Ar4 independently represents an aromatic ring, each of Ri and Rj 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, and g represents an integer of 0 or more and 5 or less.) A divalent organic group having 1 to 50 carbon atoms represented by, and The following formulas (9) to (18):

[0092]

Chemical formula

[0093] (In formula (12), h represents an integer of 4 or more and 7 or less, and in formula (17), each Rk independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.) It is preferably selected from the group consisting of divalent groups represented by

[0094] In formulas (7) and (8), examples of the aromatic rings represented by Ar3 and Ar4 can be the same as those exemplified for Ar1. In formulas (7) and (8), 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 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 Re, Rf, Ri, and Rj, can be the same as those exemplified for Ra. Each group in formulas (7) and (8) may each have a substituent.

[0095] Examples of the compound represented by formula (1) include bisphenol A type cyanate, bisphenol E type cyanate, and diallyl bisphenol A type cyanate.

[0096] Since a cyanate ester compound capable of more accurately measuring the cyanate group equivalent can be obtained, as the compound represented by formula (1), the compound represented by the following formula (19) is preferable.

[0097]

Chemical formula

[0098] In formula (19), each Ar5 independently represents an aromatic ring, each Rl independently represents a methylene group, a methyleneoxy group, a methyleneoxymethylene group, an oxymethylene group, or a group formed by linking two or more of these, Rm and Rn 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, i represents the number of bonding of the cyanate group to Ar5, and each independently is an integer of 1 or more and 3 or less, j represents the number of bonding of Rm to Ar5, and represents the number obtained by subtracting (i + 2) from the number of substitutable groups of Ar5, k represents the number of bonding of Rn to Ar5, and represents the number obtained by subtracting 2 from the number of substitutable groups of Ar5, l represents an integer of 1 or more, m represents an integer of 1 or more, and the arrangement of each repeating unit is arbitrary. Each group in formula (19) may each have a substituent.

[0099] In formula (19), examples of the aromatic ring represented by Ar5 can be the same as those exemplified for Ar1. In formula (19), 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 can be the same as those exemplified for Ra. l represents an integer of 1 or more, preferably an integer of 1 or more and 10 or less, more preferably an integer of 1 or more and 5 or less. m represents an integer of 1 or more, preferably an integer of 1 or more and 10 or less, more preferably an integer of 1 or more and 5 or less.

[0100] (Compound represented by formula (2)) The compound represented by formula (2) is shown below.

[0101]

Chemical formula

[0102] In formula (2), Ar2 represents an aromatic ring, and 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 the number of cyanate groups bonded to Ar2 and is an integer of 1 or more and 3 or less. e represents the number of Rb bonded to Ar2 and represents the number obtained by subtracting (d + 2) from the number of substitutable positions of Ar2. Each group in formula (2) may each have a substituent.

[0103] In formula (2), examples of the aromatic ring represented by Ar2 can be the same as those exemplified for Ar1. In formula (2), examples of the alkenyl group having 2 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 Rb can be the same as those exemplified for Ra.

[0104] As the cyanate ester compound of this embodiment, a compound represented by the following formula (20) is preferable.

[0105]

Chemical formula

[0106] In formula (20), each Ar6 independently represents an aromatic ring, each Ro independently represents a methylene group, a methyleneoxy group, a methyleneoxymethylene group, or an oxymethylene group, or a group formed by linking two or more of these, Rp and Rq 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, n represents the number of cyanate groups bonded to Ar6 and is an integer of 1 or more and 3 or less, o represents the number of Rp bonded to Ar6 and represents the number obtained by subtracting (n + 2) from the number of substitutable positions of Ar6, p represents the number of Rq bonded to Ar6 and represents the number obtained by subtracting 2 from the number of substitutable positions of Ar6, and i represents an integer of 1 or more. Each group in formula (20) may each have a substituent.

[0107] In formula (20), examples of the aromatic ring represented by Ar6 are the same as those exemplified for Ar1. In formula (20), 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 are the same as those exemplified for Ra. i represents an integer of 1 or more, preferably an integer of 1 or more and 10 or less, and more preferably an integer of 1 or more and 5 or less.

[0108] Examples of the cyanate ester compound or its prepolymer include commercially available products such as CYTESTER (registered trademark) TA (product name), TA-100 (product name), TA-1500 (product name), and P-201 (product name) manufactured by Mitsubishi Gas Chemical Company, Inc.

[0109] 〔Method for producing cyanate ester compound〕 The method for producing the cyanate ester compound is not particularly limited, and known methods can be used. Examples of such production methods include a method of obtaining or synthesizing a hydroxy group-containing compound having a desired skeleton and modifying the hydroxy group by a known method to cyanate it. Examples of the method for cyanating the hydroxy group include the methods described in Ian Hamerton, "Chemistry and Technology of Cyanate Ester Resins," Blackie Academic & Professional.

Examples

[0110] Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not particularly limited by the following examples.

[0111] 〔Method for calculating cyanate group equivalent〕 In the examples and comparative examples, the cyanate group equivalent (g / mol) of the cyanate ester compound was calculated using the above formula (6).

[0112] 〔Example 1〕 A 100 mL glass flask equipped with a magnetic stirrer was prepared. At room temperature (about 25 °C), 0.20 g of bisphenol A cyanate ester (CYTESTER (registered trademark) TA (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc.) as a cyanate ester compound and 18.0 g of dichloromethane (manufactured by Fujifilm Wako Pure Chemical Corporation) were added to the flask, and the bisphenol A cyanate ester was dissolved in dichloromethane to obtain a homogeneous solution. 0.50 g (3.9 mmol) of dibutylamine (manufactured by Fujifilm Wako Pure Chemical Corporation) as a secondary amine was weighed, and the entire amount was added to the homogeneous solution. A stir bar was placed and the mixture was mixed and stirred with a magnetic stirrer for 1 hour to prepare a first mixture.

[0113] Next, at room temperature (about 25 °C), 5.0 g (49 mmol) of acetic anhydride (manufactured by Fujifilm Wako Pure Chemical Corporation) as a carboxylic acid anhydride was added to the first mixture, and the mixture was mixed and stirred with a magnetic stirrer for 3 hours to prepare a second mixture. The addition amount of the carboxylic acid anhydride was 12.5 mol with respect to 1 mol of the secondary amine contained in the first mixture.

[0114] Using a potentiometric automatic titrator (OMNIS (registered trademark) Titration (trade name) manufactured by Metrohm Japan Co., Ltd.), acid titration was performed on the second mixture with a 0.1 N acetic acid solution of perchloric acid (manufactured by Fujifilm Wako Pure Chemical Corporation, factor: 1.000) as an acid standard solution, and the titration volume T1 (mL) at the end point was determined. As a result, the titration volume T1 was 13.9643 mL.

[0115] On the other hand, in order to perform a blank test, a second mixture was prepared in the same manner as above except that the cyanate ester compound was not included. Acid titration was performed on the second mixture in the same manner as above, and the titration volume T0 (mL) was determined. As a result, the titration volume T0 was 0.0530 mL.

[0116] Using the obtained titration amounts T1 and T0, the cyanate group equivalent (g / mol) of the cyanate ester compound was calculated according to the above-described method for calculating the cyanate group equivalent. The results are shown in Table 1.

[0117] [Example 2] The cyanate group equivalent (g / mol) was calculated in the same manner as in Example 1, except that 0.28 g of a prepolymer of bisphenol A cyanate ester (trade name TA-100, manufactured by Mitsubishi Gas Chemical Company, Inc.) was used instead of 0.20 g of bisphenol A cyanate ester (trade name CYTESTER (registered trademark) TA, manufactured by Mitsubishi Gas Chemical Company, Inc.). The results are shown in Table 1.

[0118] [Example 3] The cyanate group equivalent (g / mol) was calculated in the same manner as in Example 1, except that 0.22 g of a prepolymer of bisphenol A cyanate ester (trade name TA-1500, manufactured by Mitsubishi Gas Chemical Company, Inc.) was used instead of 0.20 g of bisphenol A cyanate ester (trade name CYTESTER (registered trademark) TA, manufactured by Mitsubishi Gas Chemical Company, Inc.). The results are shown in Table 1.

[0119] [Example 4] The cyanate group equivalent (g / mol) was calculated in the same manner as in Example 1, except that 0.25 g of bisphenol E cyanate ester (trade name P-201, manufactured by Mitsubishi Gas Chemical Company, Inc.) was used instead of 0.20 g of bisphenol A cyanate ester (trade name CYTESTER (registered trademark) TA, manufactured by Mitsubishi Gas Chemical Company, Inc.). The results are shown in Table 1.

[0120] [Example 5] The cyanate group equivalent (g / mol) was calculated in the same manner as in Example 1, except that a 0.1 N methanol solution of hydrochloric acid (manufactured by FUJIFILM Wako Pure Chemical Corporation, factor: 1.000) was used instead of a 0.1 N acetic acid solution of perchloric acid (manufactured by FUJIFILM Wako Pure Chemical Corporation) as the acid standard solution. The results are shown in Table 1.

[0121] [Example 6] Instead of using 0.20 g of bisphenol A cyanate ester (CYTESTER (registered trademark) TA (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc.), 0.21 g was used. Instead of using 0.50 g (3.9 mmol) of dibutylamine (manufactured by Fujifilm Wako Pure Chemical Corporation), 0.50 g (4.9 mmol) of dipropylamine (manufactured by Fujifilm Wako Pure Chemical Corporation) was used. Instead of using 5.0 g (49 mmol) of acetic anhydride (manufactured by Fujifilm Wako Pure Chemical Corporation), 5.0 g (38 mmol) of propionic anhydride (manufactured by Fujifilm Wako Pure Chemical Corporation) was used. The cyanate group equivalent (g / mol) was calculated in the same manner as in Example 1. The results are shown in Table 1.

[0122] [Example 7] The cyanate group equivalent (g / mol) was calculated in the same manner as in Example 1, except that 16.0 g (156 mmol) was used instead of 5.0 g (49 mmol) of acetic anhydride (manufactured by Fujifilm Wako Pure Chemical Corporation). The addition amount of the carboxylic anhydride was 40.0 mol with respect to 1 mol of the secondary amine contained in the first mixed solution. The results are shown in Table 1.

[0123] [Example 8] Instead of using 0.20 g of bisphenol A cyanate ester (CYTESTER (registered trademark) TA (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc.), 0.23 g was used. Instead of using 0.50 g (3.9 mmol) of dibutylamine (manufactured by Fujifilm Wako Pure Chemical Corporation), 3.00 g (23.4 mmol) was used. Instead of using 5.0 g (49 mmol) of acetic anhydride (manufactured by Fujifilm Wako Pure Chemical Corporation), 30.0 g (293 mmol) was used. The cyanate group equivalent (g / mol) was calculated in the same manner as in Example 1. The results are shown in Table 1.

[0124] [Example 9] Instead of using 0.20 g of bisphenol A cyanate ester (CYTESTER (registered trademark) TA (product name) manufactured by Mitsubishi Gas Chemical Company, Inc.), 0.22 g was used. Instead of using 0.50 g (3.9 mmol) of dibutylamine (manufactured by Fujifilm Wako Pure Chemical Corporation), 0.67 g (4.0 mmol) of diphenylamine (manufactured by Fujifilm Wako Pure Chemical Corporation) was used. Instead of using 5.0 g (49 mmol) of acetic anhydride (manufactured by Fujifilm Wako Pure Chemical Corporation), 9.0 g (40 mmol) of benzoic anhydride (manufactured by Fujifilm Wako Pure Chemical Corporation) was used. The cyanate group equivalent (g / mol) was calculated in the same manner as in Example 1 except for the above. The addition amount of the carboxylic anhydride was 10.0 mol per 1 mol of the secondary amine contained in the first mixed solution. The results are shown in Table 1.

[0125] 〔Comparative Example 1〕 The cyanate group equivalent (g / mol) was calculated in the same manner as in Example 1 except that acetic anhydride was not added and 0.1N hydrochloric acid / methanol solution (manufactured by Fujifilm Wako Pure Chemical Corporation) was used instead of 0.1N perchloric acid / acetic acid titration solution (manufactured by Fujifilm Wako Pure Chemical Corporation). The results are shown in Table 1.

[0126]

Table 1

[0127] As shown in Table 1, according to the method for measuring the cyanate group equivalent of the cyanate ester compound of the present embodiment, for example, in Example 1, the cyanate group equivalent of bisphenol A cyanate ester was calculated to be 144.12 (g / mol). Considering that the theoretical equivalent value obtained from the molecular weight (278.32) of bisphenol A cyanate ester is 139.16 (g / mol), this value is slightly higher than the theoretical equivalent value. However, considering that bisphenol A cyanate ester contains impurities and moisture that do not contain cyanate groups, it can be said to be a reasonable value.

Industrial Applicability

[0128] According to the method of the present invention, the cyanate group equivalent of the cyanate ester compound can be accurately measured. Therefore, for example, when curing a thermosetting resin and a cyanate ester compound, the mixing ratio of the thermosetting resin and the cyanate ester compound can be adjusted to a suitable range. As a result, it becomes possible to improve the physical properties of the cured product and to stabilize it.

Claims

1. A method for measuring the cyanate group equivalent of a cyanate ester compound having a cyanate group in the molecule, comprising: mixing the cyanate ester compound and a secondary amine to prepare a first mixed solution; mixing the first mixed solution and a carboxylic anhydride to prepare a second mixed solution; performing acid titration on the second mixed solution to measure the cyanate group equivalent of the cyanate ester compound. A method comprising the above steps.

2. The method according to claim 1, wherein the secondary amine comprises one or more selected from the group consisting of diethylamine, dipropylamine, dibutylamine, diisopropylamine, and diphenylamine.

3. The method according to claim 1 or 2, wherein the cyanate ester compound comprises one or more selected from the group consisting of a cyanate ester compound having one or more cyanate groups in the molecule and its prepolymer.

4. The method according to claim 1 or 2, wherein the cyanate ester compound comprises a compound represented by the following formula (1) or a compound represented by the following formula (2). 【Chemical 1】 (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. a is Ar 1 represents the number of bonding cyanate groups to 1 , and each independently is an integer of 1 or more and 3 or less. b is Ar 1 represents the number of bonds of Ra with respect to Ar, and each independently represents the number obtained by subtracting (a + 2) from the substitutable valence number of Ar 1 ​ c is an integer of 1 or more and 50 or less. 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 by 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. 【Chemical Formula 2】 (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 is Ar 2 indicating the number of bonding cyanate groups to, and being an integer of 1 or more and 3 or less e is Ar 2 indicates the number of binding sites of Rb to Ar, and represents the number obtained by subtracting (d + 2) from the number of replaceable bases of Ar 2 .

5. The method according to claim 1 or 2, wherein the carboxylic anhydride comprises one or more selected from the group consisting of acetic anhydride, propionic anhydride, and benzoic anhydride.

6. In the step of preparing the second mixed solution, the addition amount of the carboxylic anhydride is 1.0 mol or more and 50 mol or less with respect to 1 mol of the secondary amine contained in the first mixed solution. The method according to claim 1 or 2.

7. The method according to claim 1 or 2, wherein the acid titration is carried out using an acetic acid solution of perchloric acid or a methanol solution of hydrochloric acid.

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