JP6882737B2 - Benzoxazine compound, its production method and benzoxazine resin - Google Patents

Description

The present invention relates to a novel benzoxazine compound, a method for producing the same, and a benzoxazine resin which is a cured product of the benzoxazine compound.

The benzoxazine compound refers to a compound containing a benzoxazine ring having a benzene skeleton and an oxazine skeleton, and the benzoxazine resin, which is a cured product (polymer) thereof, has excellent physical properties such as heat resistance and mechanical strength, and has many properties. It is used as a high-performance material for various applications in various fields.
Patent Document 1 discloses a novel benzoxazine compound having a specific structure and a method for producing the same, wherein the benzoxazine compound has a high thermal conductivity, and the benzoxazine resin curing having a high thermal conductivity due to the benzoxazine compound. It states that it is possible to manufacture a product.
Patent Document 2 discloses a thermosetting resin in which a part or all of the reactive ends of a polybenzoxazine resin having a specific benzoxazine ring structure in the main chain is sealed, and the thermosetting resin is used as a solvent. It describes that it is excellent in storage stability when dissolved.

Non-Patent Document 1 discloses indanbisphenol benzoxazine and spirobiindanbisphenol benzoxazine as novel benzoxazine compounds, and describes the results of measuring physical properties such as the glass transition point of these polymers.

Japanese Unexamined Patent Publication No. 2013-60407 Japanese Unexamined Patent Publication No. 2012-36318

C.T. Vijayakumar et al. “Structurally diverse benzoxazines: synthesis, polymerization, and thermal stability” Designed Monomers and Polymers, Taylor & Francis 2014 Vol.17, No.1, p.47-57

An object of the present invention is a novel benzoxazine compound and a method for producing the same, which can obtain a highly heat-resistant cured product showing a high weight retention rate because the glass transition temperature is high and it is difficult to thermally decompose, and the cured product. The purpose is to provide a benzoxazine resin.

As a result of diligent studies to solve the above problems, the present inventors have developed a benzoxazine compound having a specific ring structure and an organic group, which is excellent in heat resistance, heat decomposition property, etc., and completed the present invention. I came to do it.

［式（１）中、Ｘは２価の有機基である。］That is, according to the present invention, the benzoxazine compound represented by the following formula (1) is provided.

[In formula (1), X is a divalent organic group. ]

Further, according to the present invention from another viewpoint, a method for producing a benzoxazine compound having the benzoxazine ring forming reaction according to any one of the following [A] or [B] is provided.
[A] A benzoxazine ring forming reaction in which a nitrogen-containing phenol derivative 1, a diamine, and a formaldehyde or a formaldehyde derivative are reacted at the same time.
[B] A step 1 in which a nitrogen-containing phenol derivative 2 is reacted with a diamine to obtain an intermediate 1 and a step 2 in which the intermediate 1 is reduced and further reacted with a phenol derivative to obtain an intermediate 2 are intermediate. A benzoxazine ring-forming reaction comprising the step 3 of reducing the body 2 and further reacting it with a formaldehyde or a formaldehyde derivative.

Further, according to the present invention from another viewpoint, a benzoxazine resin which is a cured product of a thermosetting resin raw material containing the benzoxazine compound of the formula (1) is provided.

The benzoxazine compound according to the formula (1) of the present invention is a novel compound having four benzoxazine rings, which comprises a structure in which a dimer having two benzoxazine rings is linked by two divalent organic groups X. Compound. Due to the structure represented by the formula (1), the benzoxazine compound of the present invention has features that it has good heat resistance after curing, is hard to be thermally decomposed, and has a high glass transition temperature. Therefore, the benzoxazine resin obtained by thermosetting using the benzoxazine compound of the present invention as a raw material has excellent characteristics of high heat resistance and extremely high high-temperature mechanical strength. Therefore, it can be used as a high-strength, high-heat-resistant material in the fields of adhesives, encapsulants, paints, matrix resins for composite materials, and the like.

^{1 1} HNMR and ¹³ 1 CNMR spectrum charts of the tetrafunctional benzoxazine of Example 1. ^{1 1} HNMR and ¹³ 1 CNMR spectrum charts of the tetrafunctional benzoxazine of Example 2. ^{1 1} HNMR and ¹³ 1 CNMR spectrum charts of the tetrafunctional benzoxazine of Example 3. FIG. 5 is a ^{1 1} HNMR spectrum diagram of DDS-2 of Example 4. FIG. 5 is a ^{1 1} HNMR spectrum diagram of DDS-3 of Example 4. ^{FIG. 5 is a 1 1} HNMR spectrum diagram of DDS-4 of Example 4. ^{FIG. 5 is a 1 1} HNMR spectrum diagram of DDS-5 of Example 4. ^{1 1} HNMR and ¹³ 1 CNMR spectrum charts of the tetrafunctional benzoxazine of Example 4. FIG. 5 is a ¹ HNMR and ¹³ 1 CNMR spectrum diagrams of the tetrafunctional benzoxazine of Example 5. ^{6 is a 1} HNMR and ¹³ 1 CNMR spectrum diagrams of the tetrafunctional benzoxazine of Example 6. ^{1 1} HNMR and ¹³ 1 CNMR spectrum charts of the tetrafunctional benzoxazine of Example 7.

Hereinafter, the present invention will be described in detail.
The benzoxazine compound of the formula (1) has a structure in which a dimer having two benzoxazine rings is linked by two divalent organic groups X. Since the compound has four benzoxazine rings, it may be hereinafter referred to as a tetrafunctional benzoxazine.

式（５）の各有機基において、波線は当該部分でベンゾオキサジン環のＮ（窒素）と結合していることを示す。X is a divalent organic group, preferably an aliphatic hydrocarbon group, an aromatic ring-containing hydrocarbon group, an organic group having an ether group (−O−) and an aromatic ring, and an ester group [−C (= O—). ) -O-] and an organic group having an aromatic ring, an amide group [-C (= O) -NH-] and an organic group having an aromatic ring, or a sulfide group (-S-) and an aromatic ring. It is an organic group. The aliphatic hydrocarbon group is preferably a cyclic aliphatic hydrocarbon group. It is preferable that the ether group, ester group, amide group, and sulfide group all exist as a linking group that connects the aromatic ring and the aromatic ring.
As a specific example, the organic group represented by the following formula (5) can be mentioned.

In each organic group of formula (5), the wavy line indicates that it is bonded to N (nitrogen) of the benzoxazine ring at that portion.

Specific examples of the benzoxazine compound of the formula (1) (hereinafter, may be simply referred to as the compound of the formula (1)) include a group of tetrafunctional benzoxazine compounds represented by the following formula (6). it can.

Next, a method for producing the compound of the formula (1) will be described.
The compound of the formula (1) can be produced by a method for producing a benzoxazine compound having the benzoxazine ring forming reaction of either [A] or [B] described below.
[A] is a benzoxazine ring-forming reaction in which a nitrogen-containing phenol derivative 1 is simultaneously reacted with a diamine such as an aliphatic diamine or an aromatic diamine and a formaldehyde or a formaldehyde derivative. The following compound (b), 2-((4-hydroxyphenyl) amino methyl) phenol, can be exemplified. Formaldehyde may be used in the form of formalin, and examples of formaldehyde derivatives include multimers such as trioxane and paraformaldehyde, and polymers.

As a method for producing a benzoxazine compound having the benzoxazine ring forming reaction of [A], the method shown below can be mentioned as a preferable example. That is, it is a manufacturing method by the steps (X) to (Z) described below.
Step (X); Compounds (a) [2-(((4-hydroxyphenyl)) are produced by the reaction of salicylaldehyde (2-hydroxybenzaldehyde) and p-aminophenol (4-aminophenol) represented by the formula (2). imino) methyl) phenol] is a process of synthesizing.

Step (Y); A step of synthesizing compound (b) [2-((4-hydroxyphenyl) amino methyl) phenol (nitrogen-containing phenol derivative 1)] by the reduction reaction represented by the formula (3) of compound (a).

［式（１）中、Ｘは２価の有機基である。］Step (Z); A step of synthesizing a compound of the following formula (1) by a reaction represented by the formula (4) of the compound (b), a diamine, and a formaldehyde or a formaldehyde derivative. In each formula of the present application, formaldehyde or formaldehyde derivative is _{represented as (CH 2} O).

[In formula (1), X is a divalent organic group. ]

In the step (X), the theoretical reaction molar ratio of salicylaldehyde to p-aminophenol is 1: 1. However, in the actual synthetic reaction, p-aminophenol 0.5 to 1 mol with respect to 1 mol of salicylaldehyde. 2.0 mol is preferable, and 1.0 to 2.0 mol is more preferable. This is because compound (a) can be synthesized in high yield.
Examples of the reaction solvent include alcohols, hydrocarbons, aromatic hydrocarbons, ethers, esters, halogen-containing solvents and the like, and from the viewpoint of solubility of the reactants and products, methanol, ethanol and n -Lower alcohols such as propanol and isopropanol are preferred.
The reaction temperature is preferably room temperature or higher and reflux temperature or lower, and more preferably 30 ° C. or higher and 60 ° C. or lower. This is because the reaction rate is good. The reaction time may be about 1 to 10 hours.

Since the reaction product containing the compound (a) obtained by the reaction of the formula (2) may contain impurities, the reaction product is purified by recrystallization, column chromatography purification, solvent washing, etc. to obtain a high-purity compound. (A) is preferable. This is because the compound (b) can be obtained in a high yield in the next step (Y). Examples of the purification solvent include alcohols, hydrocarbons, aromatic hydrocarbons, ethers, esters, halogen-containing solvents and the like.

In the step (Y), a commonly used method for reducing imine (contact hydrogen reduction, reduction with a metal hydride, etc.) can be applied. When a metal hydride is used, sodium borohydride (NaBH ₄ ), lithium aluminum hydride (LiAlH ₄ ) and the like can be used. When sodium borohydride is used, the theoretical reaction molar ratio of compound (a) and sodium borohydride represented by the formula (3) is 2: 1. However, in an actual synthetic reaction, 1 mol of compound (a) is used. On the other hand, 0.5 to 4.0 mol of sodium borohydride is preferable. This is because compound (b) can be synthesized in high yield. In the case of catalytic hydrogen reduction, a supported catalyst having a metal such as nickel, palladium, platinum or a compound thereof can be used as the catalyst. The hydrogen pressure is preferably from normal pressure to 10 atm.
As the reaction solvent, alcohols, hydrocarbons, aromatic hydrocarbons, ethers, esters and the like can be exemplified in any of the reduction reactions, and methanol and ethanol can be used from the viewpoint of solubility of the reactants and products. , N-propanol, isopropanol and other lower alcohols are preferred.
The reaction temperature is preferably 0 ° C. or higher and reflux temperature or lower, and more preferably 20 ° C. or higher and 50 ° C. or lower. This is because the reaction rate is good. The reaction time may be about 5 minutes to 1 hour.

Since the reaction product containing the compound (b) obtained by the reaction of the formula (3) may contain impurities, the reaction product is purified by recrystallization, column chromatography purification, solvent washing or the like to obtain a high-purity compound. (B) is preferable. This is because the compound (1) can be obtained in a high yield in the next step (Z). Examples of the purification solvent include alcohols, hydrocarbons, aromatic hydrocarbons, ethers, esters, halogen-containing solvents and the like.

In the step (Z), the theoretical reaction molar ratio of the compound (b) and the diamine represented by the formula (4) is 2: 1. However, in the actual synthetic reaction, the diamine is added to 1 mol of the compound (b). It is preferably 0.3 to 1.0 mol, more preferably 0.5 to 1.0 mol. This is because compound (1) can be synthesized in high yield. _{For formaldehyde or formaldehyde derivatives, the theoretical amount of CH 2} O is 3 mol per 1 mol of compound (b), but in an actual synthetic reaction, CH _{2 is based on 1 mol of compound (b).} It is preferable to use formaldehyde or a formaldehyde derivative so that the amount of O is 3.0 to 4.0 mol. This is because compound (1) can be synthesized in high yield.
Examples of the reaction solvent include alcohols, aromatic hydrocarbons, ethers, esters, halogen-containing solvents and the like, and halogen-containing solvents are preferable from the viewpoint of solubility of the reactants and products. Chloroform is particularly preferable as the halogen-containing solvent.
Moreover, you may use a base as a reaction catalyst (reaction accelerator). The base is preferably a weak base, and examples thereof include tertiary amines such as triethylamine.
The reaction temperature is preferably room temperature or higher and reflux temperature or lower, and more preferably 30 ° C. or higher and 70 ° C. or lower. This is because the reaction rate is good. The reaction time may be about 1 to 48 hours.

As diamines, 1,4-phenylenediamine (p-phenylenediamine), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfide, p-xylenediamine, 1,4- Step (Z) will be further described by exemplifying cyclohexanediamine and 1,4-bis (aminomethyl) cyclohexane.
The synthetic reaction of tetrafunctional benzoxazine (1a) using 1,4-phenylenediamine as a linking base material is shown in the following formula (4a).

In the synthesis of the tetrafunctional benzoxazine (1a) represented by the formula (4a), examples of the reaction solvent include alcohols, aromatic hydrocarbons, ethers, esters, halogen-containing solvents and the like, and the reactants and halogen-containing solvents can be exemplified. From the viewpoint of product solubility, halogen-containing solvents are preferable. Chloroform is particularly preferable as the halogen-containing solvent.
The reaction temperature is preferably room temperature or higher and reflux temperature or lower, and more preferably 30 ° C. or higher and 70 ° C. or lower. This is because the reaction rate is good. The reaction time may be about 1 to 48 hours.

The synthetic reaction of tetrafunctional benzoxazine (1b) when 4,4'-diaminodiphenylmethane is used as the linking base raw material is shown in the following formula (4b).

In the synthesis of the tetrafunctional benzoxazine (1b) represented by the formula (4b), examples of the reaction solvent include alcohols, aromatic hydrocarbons, ethers, esters, halogen-containing solvents and the like, and the reactants and halogen-containing solvents can be exemplified. From the viewpoint of product solubility, halogen-containing solvents are preferable. Chloroform is particularly preferable as the halogen-containing solvent.
The reaction temperature is preferably room temperature or higher and reflux temperature or lower, and more preferably 30 ° C. or higher and 70 ° C. or lower. This is because the reaction rate is good. The reaction time may be about 1 to 48 hours.

The synthetic reaction of tetrafunctional benzoxazine (1c) when 4,4'-diaminodiphenyl ether is used as the linking base raw material is shown in the following formula (4c).

In the synthesis of the tetrafunctional benzoxazine (1c) represented by the formula (4c), examples of the reaction solvent include alcohols, aromatic hydrocarbons, ethers, esters, halogen-containing solvents and the like, and the reactants and halogen-containing solvents can be exemplified. From the viewpoint of product solubility, halogen-containing solvents are preferable. Chloroform is particularly preferable as the halogen-containing solvent.
The reaction temperature is preferably room temperature or higher and reflux temperature or lower, and more preferably 30 ° C. or higher and 70 ° C. or lower. This is because the reaction rate is good. The reaction time may be about 1 to 48 hours.

When 4,4'-diaminodiphenyl sulfide, p-xylene diamine, 1,4-cyclohexanediamine, and 1,4-bis (aminomethyl) cyclohexane are also used as the linking base raw materials, the formulas (4d) to (4 g) are used, respectively. ), The above-mentioned tetrafunctional benzoxidines (1d) to (1 g) can be produced by the same step (Z) as in the formulas (4a) to (4c).

The benzoxazine ring formation reaction [B] involves the step 1 of reacting the nitrogen-containing phenol derivative 2 with the diamine to obtain the intermediate 1 and the step 1 of reducing the intermediate 1 and further reacting the phenol derivative to obtain the intermediate 2. It is a benzoxazine ring formation reaction having a step 2 of obtaining and a step 3 of reacting the intermediate 2 with a formaldehyde or a formaldehyde derivative. The nitrogen-containing phenol derivative 2 is 2-hydroxy-5-nitrobenzaldehyde, and the phenol derivative is Can exemplify salicylaldehyde. The diamines used in the benzoxazine ring formation reaction of [B] include 1,4-phenylenediamine (p-phenylenediamine), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, and 4, Examples thereof include 4'-diaminodiphenyl sulfide.
Further, formaldehyde may be used in the form of formalin, and examples of the formaldehyde derivative include multimers such as trioxane and paraformaldehyde, and polymers.

As a method for producing a benzoxazine compound having the benzoxazine ring formation reaction of [B], a method represented by the following formula (7) using 4,4'-diaminodiphenyl sulfide can be mentioned as a preferable example.

[B] will be described more specifically.
Step 1; A step of reacting the nitrogen-containing phenol derivative 2 represented by the following formula (7-1) with 4,4'-diaminodiphenyl sulfide to obtain an intermediate 1.

Step 2; A reaction for reducing the intermediate 1 represented by the following formulas (7-2) and (7-3), and a phenol derivative reacted with the reduced product 2 represented by the following formula (7-4) to form an intermediate. Step to obtain 2.
Examples of the reducing agent in step 2 include sodium borohydride, lithium aluminum hydride, tin chloride such as stannous chloride dihydrate, and the like.

Step 3; A reaction for reducing the intermediate 2 represented by the following formula (7-5) and a tetrafunctional benzoxazine (4 functional benzoxazine) by reacting the reduced product 3 represented by the following formula (7-6) with a formaldehyde or a formaldehyde derivative. The step of obtaining 1d).
As the reducing agent in the step 3, the same reducing agent as in the above step 2 can be exemplified.

In step 1, the theoretical reaction molar ratio of the nitrogen-containing phenol derivative 2 and the diamine represented by the formula (7-1) is 2: 1. However, in the actual synthetic reaction, the nitrogen-containing phenol derivative 2 has a molar ratio of 21 moles. , Phenol 0.3-1.0 mol, more preferably 0.5-1.0 mol. This is because Intermediate 1 can be synthesized in high yield.
Examples of the reaction solvent include alcohols, aromatic hydrocarbons, ethers, esters, amides, halogen-containing solvents and the like, and from the viewpoint of solubility of the reactants and products, methanol, ethanol and n- Lower alcohols such as propanol and isopropanol, and dimethylformamide are preferred. The reaction temperature is preferably room temperature or higher and reflux temperature or lower, and more preferably 30 ° C. or higher and 60 ° C. or lower. This is because the reaction rate is good. The reaction time may be about 1 to 10 hours.

The case where sodium borohydride and stannous chloride dihydrate are used as the reducing agent will be specifically described as an example of the step 2.
The theoretical reaction molar ratio shown in the formula (7-2) between Intermediate 1 and sodium borohydride is 1: 1. However, in an actual synthetic reaction, sodium borohydride is added to 11 mol of intermediate. It is preferably 1.0 to 4.0 mol. It is also possible to add hydrogen in the latter stage of the reaction. This is because the reduced product 1 can be obtained in high yield by hydrogenation. Further, in the reaction of the reduced product 1 obtained by the formula (7-2) and the stannous chloride dihydrate in the formula (7-3), stannous chloride dihydrate was added to 1 mol of the reduced product. 1.0 to 20.0 mol of hydrate is preferable. Furthermore, the theoretical reaction molar ratio of the reduced product 2 obtained by the formula (7-3) and the phenol derivative shown in the formula (7-4) is 1: 2, but in the actual synthetic reaction, the reduced product 2 is used. From 1 mol to 1 mol, the phenol derivative is preferably 2.0 to 4.0 mol. This is because Intermediate 2 can be synthesized in high yield.
Examples of the reaction solvent of the formula (7-2) include alcohols, aromatic hydrocarbons, ethers, esters, amides, halogen-containing solvents and the like, and from the viewpoint of solubility of the reactants and products. , Amides are preferred. As the amides, dimethylformamide and dimethylacetamide are particularly preferable. The reaction temperature is preferably 0 ° C. or higher and reflux temperature or lower, and more preferably room temperature or higher and 60 ° C. or lower. This is because the reaction rate is good. The reaction time may be about 4 hours to 1 week.
Examples of the reaction solvent of the formula (7-3) include alcohols, aromatic hydrocarbons, ethers, esters, amides, halogen-containing solvents and the like, and from the viewpoint of solubility of the reactants and products. , Methanol, ethanol, n-propanol, isopropanol and other lower alcohols are preferred. The reaction temperature is preferably room temperature or higher and reflux temperature or lower, and more preferably 30 ° C. or higher and 60 ° C. or lower. This is because the reaction rate is good. The reaction time may be about 1 to 10 hours.
Examples of the reaction solvent of the formula (7-4) include alcohols, aromatic hydrocarbons, ethers, esters, amides, halogen-containing solvents and the like, and from the viewpoint of solubility of the reactants and products. , A mixed solvent of alcohols and amides is preferable. A mixed solvent of ethanol as alcohols and dimethylacetamide as amides is particularly preferable. The reaction temperature is preferably room temperature or higher and reflux temperature or lower, and more preferably 30 ° C. or higher and 60 ° C. or lower. This is because the reaction rate is good. The reaction time may be about 3 to 24 hours.

Step 3 will be specifically described by taking the case where sodium borohydride is used as the reducing agent as an example.
The theoretical reaction molar ratio shown in the formula (7-5) between the intermediate 2 and sodium borohydride is 1: 1. However, in the actual synthetic reaction, sodium borohydride is compared with 21 moles of the intermediate. It is preferably 1.0 to 10.0 mol. Further, in the reaction represented by the formula (7-6) between the reduced product 3 obtained by the formula (7-5) and formaldehyde or a formaldehyde derivative, the _{theoretical amount of CH 2} O is 4 mol with respect to 1 mol of the reduced product. However, in the actual synthetic reaction, it is preferable to use formaldehyde or a formaldehyde derivative so _{that the amount of CH 2 O is 4.0 to 8.0 mol with respect to 31 mol of the reduced product.} This is because the tetrafunctional benzoxazine (1d) can be synthesized in high yield.
Examples of the reaction solvent of the formula (7-5) include alcohols, aromatic hydrocarbons, ethers, esters, amides, halogen-containing solvents and the like, and from the viewpoint of solubility of the reactants and products. , Methanol, ethanol, n-propanol, isopropanol and other lower alcohols are preferred. The reaction temperature is preferably room temperature or higher and reflux temperature or lower, and more preferably 30 ° C. or higher and 60 ° C. or lower. This is because the reaction rate is good. The reaction time may be about 1 to 10 hours.
Examples of the reaction solvent of the formula (7-6) include alcohols, aromatic hydrocarbons, ethers, esters, halogen-containing solvents and the like, and from the viewpoint of solubility of the reactants and products, halogen-containing. Solvents are preferred. Chloroform is particularly preferable as the halogen-containing solvent.
The reaction temperature is preferably room temperature or higher and reflux temperature or lower, and more preferably 30 ° C. or higher and 70 ° C. or lower. This is because the reaction rate is good. The reaction time may be about 2 hours to 3 days.

A method for identifying the structure of the compound of the formula (1) exemplified by the tetrafunctional benzoxazines (1a) to (1 g) obtained as described above will be described.
The structure of the compound of formula (1) was identified by elemental analysis, infrared spectroscopy (IR), proton NMR ( ¹ HNMR), and ¹³ CNMR. Elemental analysis shows that the measured and calculated values of each element are in good agreement, IR measurement shows a spectrum with a specific characteristic absorption peak, and both NMR measurements show chemical shifts, couplings and areas of NMR peaks. From the ratio, it is identified by the fact that each hydrogen atom and carbon atom can be reasonably assigned, and it is confirmed that the structure is of the formula (1). The specific identification method will be described with reference to the exemplified compounds of Examples described later.

For elemental analysis, for example, Yanaco CHN Corder MT-5 (manufactured by Yanaco Group Co., Ltd.) can be used to analyze the carbon, nitrogen, and hydrogen contents.

IR can be measured using, for example, Thermo Scientific NICOLET iS10 FTIR (manufactured by Thermo Fisher Scientific Inc.).

^{1 1} HNMR and ¹³ CNMR can be measured using, for example, JNM ECS400 (manufactured by JEOL RESONANCE Inc.).

The benzoxazine compound of the present invention can be subjected to thermosetting (ring-opening polymerization) to produce a novel benzoxazine resin having excellent heat resistance. The thermosetting may be performed by thermosetting the compound of the formula (1) alone or a mixture with a known benzoxazine compound other than the compound of the formula (1). Further, a raw material compound for a thermosetting resin other than the benzoxazine compound may be heat-cured.

A cured product (cured resin) of the compound of the formula (1) by thermosetting can be produced as follows. That is, ring-opening polymerization can be performed and cured under the same curing conditions as known benzoxazine compounds. For example, a cured product can be obtained by heating the compound of the formula (1) alone at 180 to 300 ° C. for 30 minutes to 10 hours. Further, as an initiator, a phenol compound, a Lewis acid, a sulfonic acid, a cation generator and the like can be used, and a cured product can be obtained by heating at 150 to 300 ° C. for 30 minutes to 10 hours. Further, a cured product can be obtained by mixing with each other benzoxazine compound and performing a curing reaction. Further, it can be co-cured with a raw material of another thermosetting resin (for example, epoxy resin, bismaleimide resin, etc.) to obtain a cured product.

ここで、ｘ１、ｙ１、ｘ２、及びｙ２は、重合度を表す整数であり、それぞれ同一であっても各々が異なっていてもよい。As an example of the curing reaction, the curing reaction of the compound of the formula (1) alone is shown in the formula (8).

Here, x1, y1, x2, and y2 are integers representing the degree of polymerization, and may be the same or different from each other.

The cured product obtained from the compound of the formula (1) has excellent heat resistance, and in particular, the cured product of the compound of the formula (1) alone has a glass transition point of 250 ° C. or higher in DSC (differential scanning calorimetry). In addition, the weight retention rate at the time of curing is 95% or more, and the heat resistance is extremely excellent.
Here, DSC is, for example, DSC-6200 (manufactured by Seiko Instrument Inc.), using, _{N 2} flow rate; 20 mL / min, heating rate can be measured by a 10 ° C. / min conditions. The weight retention rate during curing is calculated by the following formula by measuring the weight before and after curing.
Weight retention (%) = (weight after curing / weight before curing) x 100
In the present specification, the curing condition of the cured product for which the weight retention rate is calculated is 240 ° C. for 2 hours under a nitrogen atmosphere.

Hereinafter, the present invention will be specifically described with reference to examples. The production method is an example, and the benzoxazine compound according to the present invention is not limited to the following production method.
The following devices were used to identify the compounds of each example.
・ Elemental analysis; Yanaco CHN Corder MT-5 (manufactured by Yanaco Group Co., Ltd.)
・ IR; Thermo Scientific NICOLET iS10 FTIR (manufactured by Thermo Fisher Scientific Inc.)
・^{1 1} HNMR, ¹³ CNMR; JNM ECS400 (manufactured by JEOL RESONANCE Inc.)
・ DSC; DSC-6200 (manufactured by Seiko Instrument Inc.)
・ TGA; TG-DTA 6200 (manufactured by Seiko Instrument Inc.)

(Example 1)
<Tetrafunctional benzoxazine of formula (1a); 1,4-bis (2,4-dihydro-2'H- [3,6'-bibenzo [1,3] oxazin] -3'(4'H) -yl) benzene; PDA-Bz4>
1. 1. Synthesis 1-1. Synthesis of compound (a) [2-(((4-hydroxyphenyl) imino) methyl) phenol (HPIMP)] The synthesis reaction of compound (a) represented by formula (2) was carried out as follows.
27.97 g (229 mmol) of salicylaldehyde, 25 g (229 mmol) of p-aminophenol and 250 mL of ethanol were placed in a one-necked round bottom flask and reacted at 60 ° C. for 8 hours. After the reaction, the reaction solution was cooled to room temperature and ethanol was distilled off to obtain a glossy red reaction product. The reaction product was washed with 50 mL of ethanol, filtered, and dried at 60 ° C. for 48 hours to give a red powder (yield: 36.86 g, yield: 75.5%).

^{The compound (a) was confirmed by 1} H NMR and ¹³ 1 CNMR of the obtained red powder, and confirmed by the attribution of each element. The attribution results are shown in Equation (9) and Table 1. Incidentally, NMR none was measured and dissolved in _{DMSO-d 6.}

1-2. Synthesis of compound (b) [2-((4-hydroxyphenyl) amino methyl) phenol (HPAMP)] The synthesis reaction of compound (b) represented by the formula (3') was carried out as follows.
1-1. 27.46 g (128 mmol) of the compound (a) (HPIMP) synthesized in (1) and 350 mL of ethanol were placed in a flask, and 2.43 g of sodium borohydride (NaBH ₄ ) was gradually added little by little while stirring at room temperature. After that, it was stirred for 15 minutes to react. Then, 250 mL of distilled water is added to the reaction solution, the reaction product is extracted twice with 200 mL of dichloromethane each time, the dichloromethane solution containing the reaction product is washed with distilled water, and then the organic layer is formed. The dichloromethane solution was separated, anhydrous sodium sulfate was added, and the mixture was dried. After removing anhydrous sodium sulfate by filtration, dichloromethane as a solvent was distilled off from the dichloromethane solution by a rotary evaporator to obtain a yellowish white powder. The yellow-white powder was washed twice with 30 mL of dichloromethane each time and dried at 60 ° C. for 48 hours to obtain a white powder (yield: 21.5 g, yield: 77.6%).

The compound (b) was confirmed by the attribution of each element by measuring ^{1 1} H NMR and ^{13 CNMR of the obtained white solid.} The attribution results are shown in Equation (10) and Table 2. Incidentally, NMR none was measured and dissolved in _{DMSO-d 6.}

1-3. Synthesis of tetrafunctional benzoxazine (PDA-Bz4) of formula (1a) 1-2. Compound (b) (HPAMP) synthesized in (1.62 mmol), 1,4-phenylenediamine 0.628 g, (5.81 mmol), paraformaldehyde [(CH ₂ O) _n ] 1.15 g (38) .35 mmol), 0.881 g (8.71 mmol) of triethylamine, and 25 mL of chloroform were placed in a 100 mL round bottom flask and heated in an oil bath. The temperature of the oil bath was raised from room temperature to 65 ° C., and the reaction solution was refluxed for 24 hours. After refluxing for 24 hours, a uniform clear solution containing the water produced by the reaction was obtained. The clear solution was cooled to room temperature, anhydrous sodium sulfate was added, and the solution was dried. After removing anhydrous sodium sulfate by filtration, it was purified by column chromatography using chloroform as an eluent. Chloroform was distilled off to obtain a yellowish white powder. The yellowish white powder was placed in 10 mL of a hexane / ethyl acetate (70/30: volume ratio) mixed solvent, and the mixture was stirred and washed at room temperature for 30 minutes. Subsequently, after filtration, it was dried at 60 ° C. for 48 hours to obtain a white powder (yield: 1.08 g, yield: 30.45%).

The synthetic reaction formula of the tetrafunctional benzoxazine of the formula (1a) is shown in the formula (4a').

2. Identification of the tetrafunctional benzoxazine of the formula (1a): Various analyzes and measurements The fact that the compound synthesized as described above is the tetrafunctional benzoxazine of the formula (1a) is an element of the obtained white powder. Confirmed by analysis, IR measurements, ^{and 1} HNMR and ¹³ CNMR measurements. These analyzes and measurements were carried out by a conventional method using each of the above-mentioned devices. Furthermore, using the above DSC apparatus, _{N 2} flow rate; 20 mL / min, heating rate; the melting point was measured at 10 ° C. / min conditions. The melting points of the tetrafunctional benzoxazines of the other examples were measured in the same manner. The analysis and measurement results are shown below.

[Elemental analysis (as C ₃₈ H ₃₄ N ₄ O ₄ )]
-Measured values: C; 74.57, H; 5.39, N; 9.12
・ Calculated values: C; 74.73, H; 5.61, N; 9.17
[IR measurement]
3043, 3010, 2976, 2901 cm ^-1 ; (CH: Aliphatic)
1611, 1583 cm ^-1 ; (C = C: aromatic)
1362 cm ^-1 ; (CN: Aromatic)
1228, 1217 cm ^-1 ; (COC)
1175 cm ^-1 ; (CN: aliphatic)
976,952,927 cm ^-1 ; (CH: benzene ring bonded to the oxazine ring)
[Melting point]: 185 ° C

[ ^{1 1} HNMR and ¹³ CNMR measurement]
The attribution result by NMR measurement is shown in Equation (1a-1) and FIG. The upper chart of FIG. 1 shows 1 ¹ HNMR, and the lower chart ^{shows 13} 1 HNMR (the same applies hereinafter). ¹ The signal group near 7 ppm of 1 HNMR is due to 18 hydrogens in the aromatic ring. In addition, all NMR was measured by dissolving in deuterated chloroform.

3. 3. Synthesis of benzoxazine resin A [cured product of tetrafunctional benzoxazine of formula (1a)] Ring-opening polymerization (ROP) was carried out by heating at 240 ° C. for 2 hours in a nitrogen stream to obtain benzoxazine resin A. The curing reaction is represented by the following formula (8a).

4. Physical characteristics of benzoxazine resin A The glass transition point of benzoxazine resin A in DSC was 309 ° C, and the 10% weight loss temperature (T _d10 ) in TGA was 387 ° C. DSC and TGA were measured under the following measurement conditions using the above-mentioned device.
・ DSC; N ₂ flow rate: 20 mL / min, heating rate: 10 ° C / min ・ TGA; N ₂ flow rate: 50 mL / min, heating rate: 10 ° C / min In addition, the weight retention rate during curing is 98.74. %Met.

(Example 2)
<Tetrafunctional benzoxazine of formula (1b); 4,4'-bis (2,4-dihydro-2'H- [3,6'-bibenzo [1,3] oxazin] -3'(4'H) ) -yl) phenylmethane; DDM-Bz4>
1. 1. Synthesis; Synthesis of tetrafunctional benzoxazine (DDM-Bz4) of formula (1b) According to Example 1, the compound (b) obtained in Example 1, 4,4'-diaminodiphenylmethane, and paraformaldehyde And were reacted as shown in the following formula (4b') to obtain a white powder of the tetrafunctional benzoxazine of the formula (1b) (yield; 30%).

2. Identification of the tetrafunctional benzoxazine of the formula (1b): Various analyzes and measurements The fact that the compound synthesized as described above is the tetrafunctional benzoxazine of the formula (1b) is an element of the obtained white powder. Confirmed by analysis and ^{1 1} HNMR and ¹³ CNMR measurements. These analyzes and measurements were carried out in the same manner as in Example 1. The analysis and measurement results are shown below.

[Elemental analysis (as C ₄₅ H ₄₀ N ₄ O ₄ )]
-Measured values: C; 75.98, H; 5.51, N; 7.82
・ Calculated values: C; 76.12, H; 5.75, N; 7.99
[Melting point]: 161 ° C.

[ ^{1 1} HNMR and ¹³ CNMR measurement]
The attribution result by NMR measurement is shown in Equation (1b-1) and FIG. ¹ The signal group near 7 ppm of 1 HNMR is due to 22 hydrogens in the aromatic ring. In addition, all NMR was measured by dissolving in deuterated chloroform.

3. 3. Synthesis of benzoxazine resin B [cured product of tetrafunctional benzoxazine of formula (1b)] Ring-opening polymerization was carried out by heating at 240 ° C. for 2 hours in a nitrogen stream to obtain benzoxazine resin B. The curing reaction is represented by the following formula (8b).

4. Physical characteristics of benzoxazine resin B The glass transition point of benzoxazine resin B in DSC was 294 ° C, and the 10% weight loss temperature (T _d10 ) in TGA was 379 ° C. DSC and TGA were measured under the following measurement conditions using the above-mentioned device.
・ DSC; N ₂ flow rate: 20 mL / min, heating rate: 10 ° C / min ・ TGA; N ₂ flow rate: 50 mL / min, heating rate: 10 ° C / min In addition, the weight retention rate during curing is 95.88. %Met.

(Example 3)
<Tetrafunctional benzoxazine of formula (1c); 4,4'-bis (2,4-dihydro-2'H- [3,6'-bibenzo [1,3] oxazin] -3'(4'H) ) -yl) phenylether; DDE-Bz4>
1. 1. Synthesis; Synthesis of tetrafunctional benzoxazine (DDE-Bz4) of formula (1c) According to Example 1, compound (b) obtained in Example 1, 4,4'-diaminodiphenyl ether, and paraformaldehyde And were reacted as shown in the following formula (4c') to obtain a white powder of the tetrafunctional benzoxazine of the formula (1b) (yield; 18%).

2. Identification of the tetrafunctional benzoxazine of the formula (1c): Various analyzes and measurements The fact that the compound synthesized as described above is the tetrafunctional benzoxazine of the formula (1c) is an element of the obtained white powder. Confirmed by analysis and ^{1 1} HNMR and ¹³ CNMR measurements. These analyzes and measurements were carried out in the same manner as in Example 1. The analysis and measurement results are shown below.

[Elemental analysis (as C ₄₄ H ₃₈ N ₄ O ₅ )]
-Measured values: C; 74.33, H; 5.26, N; 7.86
・ Calculated values: C; 74.62, H; 5.45, N; 7.97
[Melting point]: 163 ° C

[ ^{1 1} HNMR and ¹³ CNMR measurement]
The attribution result by NMR measurement is shown in the formula (1c-1) and FIG. ¹ The signal group near 7 ppm of 1 HNMR is due to 22 hydrogens in the aromatic ring. In addition, all NMR was measured by dissolving in deuterated chloroform.

3. 3. Synthesis of benzoxazine resin C [cured product of tetrafunctional benzoxazine of formula (1c)] Ring-opening polymerization was carried out by heating at 240 ° C. for 2 hours in a nitrogen stream to obtain benzoxazine resin C. The curing reaction is represented by the following formula (8c).

4. Physical Properties of Benoxazine Resin C The glass transition point of benzoxazine resin C in DSC was 285 ° C., and the 10% weight loss temperature (T _d10 ) in TGA was 368 ° C. DSC and TGA were measured under the following measurement conditions using the above-mentioned device.
・ DSC; N ₂ flow rate: 20 mL / min, heating rate: 10 ° C / min ・ TGA; N ₂ flow rate: 50 mL / min, heating rate: 10 ° C / min In addition, the weight retention rate during curing is 96.30. %Met.

(Example 4)
<Tetrafunctional benzoxazine of formula (1d); 4,4'-bis (2,4-dihydro-2'H- [3,6'-bibenzo [1,3] oxazin] -3'(4'H) ) -yl) phenylsulfide; DDS-Bz4>
1. 1. Synthesis 1-1.4,4'-Bis (5-nitoro- (salicylideneamino) phenyl) sulfide (DDS-1) (Intermediate 1) synthesis
The synthesis reaction of DDS-1 was carried out as follows.
2-Hydroxy-5-nitrobenzaldehyde and 4,4'-diaminodiphenyl sulfide were dissolved in DMF (dimethylformamide) and reacted at room temperature for 4 hours to obtain a red powder of DDS-1 (yield; 84%). The synthetic reaction of DDS-1 is shown in the following formula (7-1).

DDS-2であることは、得られた黄色粉末の^１ＨＮＭＲを測定し、各プロトンの帰属により確認した。各プロトンの帰属を示した^１ＨＮＭＲを図４に示す。なお、^１ＨＮＭＲはＤＭＳＯ−ｄ_６に溶解して測定した。Synthesis of 1-2.4.4,4'-Bis ((5-nitoro-2-hydroxyphenyl) methylamino) phenylsulfide (DDS-2)
DDS-1 and sodium borohydride (3.2 equivalents relative to DDS-1) were reacted at room temperature in a hydrogen atmosphere for 4 days to obtain a yellow powder of DDS-2 (yield; 46%). ). The synthetic reaction of DDS-2 is shown in the following formula (7-2').

The fact that it was DDS-2 was ^{confirmed by measuring 1 1} HNMR of the obtained yellow powder and assigning each proton. ^{1 1} HNMR showing the attribution of each proton is shown in FIG. ^{Incidentally,} 1 HNMR was measured and dissolved in _{DMSO-d 6.}

DDS-3であることは、得られた淡茶色粉末の^１ＨＮＭＲを測定し、各プロトンの帰属により確認した。各プロトンの帰属を示した^１ＨＮＭＲを図５に示す。なお、^１ＨＮＭＲはＤＭＳＯ−ｄ６に溶解して測定した。Synthesis of 1-3.4.4,4'-Bis ((5-amino-2-hydroxyphenyl) methylamino) phenylsulfide (DDS-3)
DDS-2 and stannous chloride dihydrate (10 times the molar amount of DDS-2) are dissolved in ethanol and reacted at 85 ° C. for 2 hours to obtain a light brown powder of DDS-3. (Yield; 98%). The synthetic reaction of DDS-3 is shown in the following formula (7-3').

The fact that it was DDS-3 was ^{confirmed by 1} HNMR of the obtained light brown powder and the attribution of each proton. ^{1 1} HNMR showing the attribution of each proton is shown in FIG. ^{1 1} HNMR was measured by dissolving it in DMSO-d6.

DDS-4であることは、得られた黄色粉末の^１ＨＮＭＲを測定し、各プロトンの帰属により確認した。各プロトンの帰属を示した^１ＨＮＭＲを図６に示す。なお、^１ＨＮＭＲはＤＭＳＯ−ｄ６に溶解して測定した。Synthesis of 1-4.4.4,4'-Bis ((5-salicylideneamino-2-hydroxyphenyl) methylamino) phenylsulfide (DDS-4) (Intermediate 2)
DDS-3 and salicylaldehyde were dissolved in a 1/1 mixed solvent of ethanol / dimethylacetamide and reacted at 60 ° C. for 10 hours to obtain a yellow powder of DDS-4 (yield; 41%). The synthetic reaction of DDS-4 is shown in the following formula (7-4).

The fact that it was DDS-4 was ^{confirmed by measuring 1 1} HNMR of the obtained yellow powder and assigning each proton. ^{1 1} HNMR showing the attribution of each proton is shown in FIG. ^{1 1} HNMR was measured by dissolving it in DMSO-d6.

DDS-5であることは、得られた黄色結晶の^１ＨＮＭＲを測定し、各プロトンの帰属により確認した。各プロトンの帰属を示した^１ＨＮＭＲを図７に示す。なお、^１ＨＮＭＲはＤＭＳＯ−ｄ６に溶解して測定した。Synthesis of 1-5.4,4'-Bis ((5- (2'-hydroxyphenyl) methylamino-2-hydroxyphenyl) methylamino) phenylsulfide (DDS-5)
DDS-4 and sodium borohydride (5.8 eq with respect to DDS-4) were reacted at room temperature for 2.5 hours to obtain yellow crystals of DDS-5 (yield; 81%). .. The synthetic reaction of DDS-5 is shown in the following formula (7-5').

The fact that it was DDS-5 was ^{confirmed by measuring 1 1} HNMR of the obtained yellow crystals and assigning each proton. ^{1 1} HNMR showing the attribution of each proton is shown in FIG. ^{1 1} HNMR was measured by dissolving it in DMSO-d6.

1-6. Synthesis of tetrafunctional benzoxazine (DDS-Bz4) of formula (1d)
DDS-5 and paraformaldehyde (5.6 times the molar amount of DDS-5) are dissolved in chloroform, reacted at 65 ° C. for 20 hours, and stirred for another 4 hours after the yellow suspension becomes transparent. did. Subsequently, excess paraformaldehyde was removed by filtration. Perform water removal in the presence of sodium sulfate, after further filtration, chloroform, and the residue such volatiles were removed under reduced pressure to give a white powder. The obtained white powder was recrystallized from a 4/1 mixed solvent of chloroform / hexane to obtain a white powder of DDS-Bz4 (yield; 41%). The synthetic reaction of the tetrafunctional benzoxazine (DDS-Bz4) of the formula (1d) is shown in the following formula (7-6').

2. Identification of the tetrafunctional benzoxazine of the formula (1d): Various analyzes and measurements The fact that the compound synthesized as described above is the tetrafunctional benzoxazine of the formula (1d) is an elemental analysis of the obtained white crystals. , And ^{1 1} HNMR and ¹³ CNMR measurements. These analyzes and measurements were carried out in the same manner as in Example 1. The analysis and measurement results are shown below.

[Elemental analysis (as C ₄₄ H ₃₈ N ₄ O ₄ S)]
-Measured values: C; 72.31, H; 5.20, N; 7.58
・ Calculated values: C; 72.63, H; 5.33, N; 7.79
[Melting point]: 188 ° C

[ ^{1 1} HNMR and ¹³ CNMR measurement]
The attribution result by NMR measurement is shown in the formula (1d-1) and FIG. ¹ The signal group near 7 ppm of 1 HNMR is due to 22 hydrogens in the aromatic ring. In addition, all NMR was measured by dissolving in deuterated chloroform.

3. 3. Synthesis of benzoxazine resin D [cured product of tetrafunctional benzoxazine of formula (1d)] Ring-opening polymerization was carried out by heating at 240 ° C. for 2 hours in a nitrogen stream to obtain benzoxazine resin D. The curing reaction is shown in the following formula (8d).

4. Physical Properties of Benoxazine Resin D The glass transition point of benzoxazine resin D in DSC was 325 ° C, and the 10% weight loss temperature (T _d10 ) in TGA was 370 ° C. DSC and TGA were measured under the following measurement conditions using the above-mentioned device.
DSC; N ₂ flow rate: 20 mL / min, heating rate: 10 ° C / min ・ TGA; N ₂ flow rate: 50 mL / min, heating rate: 10 ° C / min In addition, the weight retention rate during curing is 95.94. %Met.

(Example 5)
<Tetrafunctional benzoxazine of formula (1e); 1,4-bis [(2,4-dihydro-2'H- [3,6'-bibenzo [1,3] oxazin] -3'(4'H) ) -yl) methyl] benzene; XDA-Bz4 ＞
1. 1. Synthesis; Synthesis of tetrafunctional benzoxazine of formula (1e) 2.5 g (11.62 mmol) of compound (b) obtained in Example 1, 0.79 g of p-xylene diamine, (5.81 mmol), paraformaldehyde [ (CH ₂ O) _n ] 1.15 g (38.35 mmol), 0.881 g (8.71 mmol) of triethylamine, and 25 mL of chloroform were placed in a 100 mL round bottom flask and refluxed for 24 hours. After refluxing for 24 hours, a uniform clear solution containing the water produced by the reaction was obtained. The clear solution was cooled to room temperature, anhydrous sodium sulfate was added, and the solution was dried. After removing anhydrous sodium sulfate by filtration, it was purified by column chromatography using ethyl acetate / hexane (1/2) as an eluent. The solvent was distilled off to obtain a yellowish white powder. The yellowish white powder was placed in 10 mL of a hexane / ethyl acetate (1/4: volume ratio) mixed solvent, and the mixture was stirred and washed at room temperature for 30 minutes. Subsequently, after filtration, it was dried at 60 ° C. for 48 hours to obtain a white powder (yield: 0.56 g, yield: 15.0%).

The synthetic reaction formula of the tetrafunctional benzoxazine of the formula (1e) is shown in the formula (4e').

2. Identification of the tetrafunctional benzoxazine of the formula (1e): Various analyzes and measurements The fact that the compound synthesized as described above is the tetrafunctional benzoxazine of the formula (1e) is an elemental analysis of the obtained white crystals. , IR measurement, ^{and 1} HNMR and ¹³ CNMR measurements. These analyzes and measurements were carried out in the same manner as in Example 1. The analysis and measurement results are shown below.

[Elemental analysis (as C ₄₀ H ₃₈ N ₄ O ₄ )]
-Measured values: C; 75.24, H; 5.95, N; 8.67
・ Calculated values: C; 75.21, H; 6.00, N; 8.77
[IR measurement]
3043, 3010, 2976, 2901 cm ^-1 ; (CH: Aliphatic)
1611, 1583 cm ^-1 ; (C = C: aromatic)
1362 cm ^-1 ; (CN: Aromatic)
1228, 1217 cm ^-1 ; (COC)
1175 cm ^-1 ; (CN: Aliphatic)
976,952,927 cm ^-1 ; (CH: benzene ring bonded to the oxazine ring)
[Melting point]: 150 ° C

[ ^{1 1} HNMR and ¹³ CNMR measurements]
The attribution result by NMR measurement is shown in the formula (1e-1) and FIG. ^{The signal group around 7 ppm of 1 1} HNMR is due to 18 hydrogens in the aromatic ring. In addition, all NMR was measured by dissolving in deuterated chloroform.

3. 3. Synthesis of benzoxazine resin E [cured product of tetrafunctional benzoxazine of formula (1e)] Ring-opening polymerization was carried out by heating at 240 ° C. for 2 hours in a nitrogen stream to obtain benzoxazine resin E. The curing reaction is represented by the following formula (8e).

4. Physical Properties of Benoxazine Resin E The glass transition point of benzoxazine resin E in DSC was 242 ° C, and the 10% weight loss temperature (T _d10 ) in TGA was 370 ° C. DSC and TGA were measured under the following measurement conditions using the above-mentioned device.
・ DSC; N ₂ flow rate: 20 mL / min, heating rate: 10 ° C / min ・ TGA; N ₂ flow rate: 50 mL / min, heating rate: 10 ° C / min In addition, the weight retention rate during curing is 95.93. %Met.

(Example 6)
<Tetrafunctional benzoxazine of formula (1f); 1,4-bis (2,4-dihydro-2'H- [3,6'-bibenzo [1,3] oxazin] -3'(4'H) -yl) cyclohexane> (CDA-Bz4)
1. 1. Synthesis; Synthesis of tetrafunctional benzoxazine of formula (1f) Based on Example 1, the compound (b) obtained in Example 1, 1,4-cyclohexanediamine, and paraformaldehyde were combined with the following formula (4f). The reaction was carried out as shown in') to obtain a white powder of tetrafunctional benzoxazine of the formula (1f) (yield; 23.6%).

2. Identification of the tetrafunctional benzoxazine of the formula (1f): Various analyzes and measurements The fact that the compound synthesized as described above is the tetrafunctional benzoxazine of the formula (1f) is an elemental analysis of the obtained white crystals. , And ^{1 1} HNMR and ¹³ CNMR measurements. These analyzes and measurements were carried out in the same manner as in Example 1. The analysis and measurement results are shown below.

[Elemental analysis (as C ₃₈ H ₄₀ N ₄ O ₄ )]
-Measured values: C; 74.00, H; 6.54, N; 9.08
・ Calculated values: C; 74.03, H; 6.75, N; 8.88
[Melting point]: 202 ° C.

[ ^{1 1} HNMR and ¹³ CNMR measurements]
The attribution result by NMR measurement is shown in the formula (1f-1) and FIG. ¹ The signal group around 7 ppm of 1 HNMR is due to 14 hydrogens of the aromatic ring, and the signal group around 1.2-2.7 ppm is due to 10 hydrogens at the base of cyclohexane. In addition, all NMR was measured by dissolving in deuterated chloroform.

3. 3. Synthesis of benzoxazine resin F [cured product of tetrafunctional benzoxazine of formula (1f)] Ring-opening polymerization was carried out by heating at 240 ° C. for 2 hours in a nitrogen stream to obtain benzoxazine resin F. The curing reaction is represented by the following formula (8f).

4. Physical characteristics of benzoxazine resin F The glass transition point of benzoxazine resin F in DSC was 225 ° C., and the 10% weight loss temperature (T _d10 ) in TGA was 356 ° C. DSC and TGA were measured under the following measurement conditions using the above-mentioned device.
・ DSC; N ₂ flow rate: 20 mL / min, heating rate: 10 ° C / min ・ TGA; N ₂ flow rate: 50 mL / min, heating rate: 10 ° C / min In addition, the weight retention rate during curing is 91.6. %Met.

(Example 7)
<Tetrafunctional benzoxazine of formula (1 g); 1,4-bis [(2,4-dihydro-2'H- [3,6'-bibenzo [1,3] oxazin] -3'(4'H) ) -yl) methyl] cyclohexane> (BAMC-Bz4)
1. 1. Synthesis; Synthesis of tetrafunctional benzoxazine of formula (1 g) According to Example 1, compound (b) obtained in Example 1, 1,4-bis (aminomethyl) cyclohexane, and paraformaldehyde were added. The reaction was carried out as shown in the following formula (4 g') to obtain a white powder of the tetrafunctional benzoxazine of the formula (1b) (yield; 20.4%).

2. Identification of the tetrafunctional benzoxazine of the formula (1 g): Various analyzes and measurements The fact that the compound synthesized as described above is the tetrafunctional benzoxazine of the formula (1 g) is an elemental analysis of the obtained white crystals. , And ^{1 1} HNMR and ¹³ CNMR measurements. These analyzes and measurements were carried out in the same manner as in Example 1. The analysis and measurement results are shown below.

[Elemental analysis (as C ₄₀ H ₄₄ N ₄ O ₄ )]
-Measured values: C; 74.51, H; 6.88, N; 8.69
・ Calculated values: C; 74.28, H; 6.79, N; 8.82
[Melting point]: No clear melting point is shown by DSC measurement.

[ ^{1 1} HNMR and ¹³ CNMR measurements]
The attribution result by NMR measurement is shown in the formula (1g-1) and FIG. ¹ The signal group around 7 ppm of 1 HNMR is due to 14 hydrogens of the aromatic ring, and the signal group around 0.9-2.0 ppm is due to 10 hydrogens at the base of cyclohexane. In addition, all NMR was measured by dissolving in deuterated chloroform.

3. 3. Synthesis of benzoxazine resin G [cured product of tetrafunctional benzoxazine of formula (1 g)] Ring-opening polymerization was carried out by heating at 240 ° C. for 2 hours in a nitrogen stream to obtain benzoxazine resin G. The curing reaction is shown in the following formula (8 g).

4. Physical Properties of Benoxazine Resin G The glass transition point of benzoxazine resin G in DSC was 213 ° C, and the 10% weight loss temperature (T _d10 ) in TGA was 379 ° C. DSC and TGA were measured under the following measurement conditions using the above-mentioned device.
・ DSC; N ₂ flow rate: 20 mL / min, heating rate: 10 ° C / min ・ TGA; N ₂ flow rate: 50 mL / min, heating rate: 10 ° C / min In addition, the weight retention rate during curing is 94.1. %Met.

The benzoxazine compound of the present invention can be used for preparing a thermosetting resin. In particular, it can be used in fields where physical properties such as adhesion, low shrinkage during curing, and high heat resistance are required. For example, it can be used as a matrix resin for composite materials, a sealing material in the electronic field, a laminated board, a paint, an adhesive, and the like.

Claims (4)

A benzoxazine compound represented by the following formula (1).

[In the formula (1), X is an aliphatic hydrocarbon group, an aromatic ring-containing hydrocarbon group, an organic group having an ether group and an aromatic ring, an organic group having an ester group and an aromatic ring, an amide group and an aromatic ring. It is an organic group having a sulfide group or an organic group having a sulfide group and an aromatic ring . ] A method for producing a benzoxazine compound, which has the benzoxazine ring synthesis reaction according to any one of the following [A] or [B].
[A] A benzoxazine ring synthesis reaction in which 2-((4-hydroxyphenyl) aminomethyl) phenol , diamine, and formaldehyde or a multimer or polymer of formaldehyde are reacted at the same time.
[B] A step 1 of reacting 2-hydroxy-5-nitrobenzaldehyde with a diamine to obtain an intermediate 1 and a step 2 of reducing the intermediate 1 and further reacting a phenol derivative to obtain an intermediate 2. , A benzoxazine ring synthesis reaction comprising the step 3 of reducing the intermediate 2 and further reacting with formaldehyde or a multimer or polymer of formaldehyde. The benzoxazine ring synthesis reaction is the above [A].
The step of synthesizing the compound (a) by the reaction of 2-hydroxybenzaldehyde and 4-aminophenol represented by the following formula (2), and
A step of synthesizing 2-((4-hydroxyphenyl) aminomethyl) phenol [ Compound (b) ] by the reaction of the compound (a) with a reducing agent represented by the following formula (3).
It comprises a step of synthesizing a benzoxazine compound represented by the following formula (1) by reacting the compound (b) represented by the following formula (4) with a diamine and a formaldehyde or a multimer or a polymer of formaldehyde. ,
The method for producing a benzoxazine compound according to claim 2.

[In the formula (1), X is an aliphatic hydrocarbon group, an aromatic ring-containing hydrocarbon group, an organic group having an ether group and an aromatic ring, an organic group having an ester group and an aromatic ring, an amide group and an aromatic ring. It is an organic group having a sulfide group or an organic group having a sulfide group and an aromatic ring . ] A cured product of a thermosetting resin raw material compound containing the benzoxazine compound according to claim 1.
Benzoxazine resin.

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