JP7654443B2 - Method for producing benzoxazine compounds - Google Patents

Description

The present invention relates to a method for producing a benzoxazine compound.

Conventionally, benzoxazine compounds have mainly been synthesized using a solution method (solution method).

For example, Patent Document 1 discloses a method for producing a compound having a dihydrobenzoxazine ring, in which a mixture of a specific bisphenol compound and formaldehyde is reacted with a primary amine while being gradually added thereto.

Patent Document 2 also discloses a manufacturing method in which a specific bisphenol compound, paraformaldehyde, and an amine compound are mixed and heat-treated in the presence of a specific solvent.

Furthermore, Non-Patent Document 1 discloses a method for producing polybenzoxazine by reacting diamine with phenol in toluene/ethanol.

On the other hand, there are also methods for producing benzoxazine compounds that do not use solvents. For example, Patent Document 3 discloses a method for producing a benzoxazine monomer using phenol, paraformaldehyde, and m-cresol as substrates.

JP 2004-217941 A JP 2012-126900 A US Patent Publication No. 2017/0166537

Sarychev et al. "Benzoxazine monomers based on aromatic diamines and investigation of their polymerization by rheological and thermal methods" J Appl Polym Sci. 2020

However, the above-mentioned method for producing benzoxazine-based compounds has room for improvement in terms of reaction time, product yield, and environmental impact. One embodiment of the present invention has been made in consideration of the above problems, and its purpose is to provide a new method for producing benzoxazine-based compounds, which has a shorter reaction time than conventional production methods, a yield of benzoxazine-based compounds equal to or greater than conventional production methods, and which has a lower environmental impact because less solvent is used in this production method compared to conventional production methods that use solvents.

As a result of intensive research to solve the above problems, the present inventors discovered that by reacting phenol, a diamine having a specific structure, and paraformaldehyde by heating at a solids concentration higher than that of the solution method, it is possible to produce a benzoxazine-based compound using a method that is superior in reaction time, product yield, and environmental impact compared to conventional methods, and thus completed the present invention. That is, one aspect of the present invention includes the following configuration.

<1> A method for producing a benzoxazine compound, comprising a reaction step of heating a mixture of (A) phenol, (B) an amine composition containing a diamine represented by the following general formula (1) and an optional monoamine, and (C) paraformaldehyde, and the solid content of the mixture is 80 to 100% by weight.

In formula (1), R1 is represented by the following general formula (2):

In formula (2), L1 and L3 are O (ether bond), L2 is any one of O (ether bond), C=O, _SO2 , C( _CH3 ) ₂ , C( _CF3 ) ₂ , or _CH2 , and p, q, r, s, and t are 0 or 1, provided that p+q+r+s+t≧1, and when s=0, p or q is 0, and when t=0, q or r is 0.

<2> The method for producing a benzoxazine compound described in <1>, wherein the heating temperature in the reaction step is 90°C or higher.

<3> The method for producing a benzoxazine compound according to <1> or <2>, wherein the heating time in the reaction step is 5 hours or less.

<4> The method for producing a benzoxazine compound according to any one of <1> to <3>, wherein the mixture contains (D) a solvent having a boiling point of 100°C or higher in an amount greater than 0% by weight and less than 20% by weight.

<5> The method for producing a benzoxazine compound according to <4>, wherein the solvent (D) is at least one selected from the group consisting of N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), 1,4-dioxane, toluene, n-butyl acetate, and diethyl carbonate.

<6> The method for producing a benzoxazine compound according to any one of <1> to <5>, further comprising a purification step of washing the reaction product if the solids concentration of the product is less than 100% by weight at the time when the reaction step is completed.

<7> The method for producing a benzoxazine compound according to any one of <1> to <6>, wherein the melting point of the diamine is 60°C or higher.

<8> The method for producing a benzoxazine-based compound according to any one of <1> to <6>, wherein the diamine is one or more selected from the compounds of the following formulas (3) to (16).

<9> A method for producing a benzoxazine compound, comprising a reaction step of heating and reacting a mixture of (A1) a monophenolic composition containing phenol, (B1) an amine composition containing a diamine and an optional monoamine, and (C) paraformaldehyde, or a mixture of (A2) a phenolic composition containing bisphenol, (B2) a monoamine composition containing aniline, and (C) paraformaldehyde, wherein the solids concentration of the mixture is 80 to 100% by weight.

According to one aspect of the present invention, a new method for producing benzoxazine-based compounds can be provided that can shorten the reaction time, improve the product yield, and reduce the environmental impact compared to conventional methods.

1. Method for producing benzoxazine compounds
A method for producing a benzoxazine compound according to one embodiment of the present invention (hereinafter also referred to as the present production method) includes a reaction step of heating a mixture of (A) phenol, (B) an amine composition containing a diamine represented by the following general formula (1) and a monoamine as an optional component, and (C) paraformaldehyde to react with each other, the solid content concentration of the mixture being 80 to 100% by weight. Here, the amine composition (B) contains 30 to 100% by weight of the diamine represented by the following general formula (1) and 70 to 0% by weight of the monoamine, preferably 50 to 100% by weight of the diamine represented by the following general formula (1) and 50 to 0% by weight of the monoamine, more preferably 70 to 100% by weight of the diamine represented by the following general formula (1) and 30 to 0% by weight of the monoamine.

In formula (1), R1 is represented by the following general formula (2):

In formula (2), L1 and L3 are O, L2 is any one of O, C=O, _SO2 , C( _CH3 ) ₂ , C( _CF3 ) ₂ , or _CH2 , and p, q, r, s, and t are 0 or 1, provided that p+q+r+s+t≧1, and when s=0, p or q is 0, and when t=0, q or r is 0.

As described above, the inventors have succeeded in shortening the reaction time and increasing the yield of the obtained benzoxazine-based compound by reducing the amount of solvent used and setting the solid content (SC) of the raw material to 80-100% by weight, which is higher than that of the conventional solution method, when producing benzoxazine-based compounds. This also makes it possible to reduce the amount of by-products or unreacted materials, resulting in an increase in the consumption of paraformaldehyde. It is surprising that a technology for producing benzoxazine-based compounds based on such an idea has not existed before.

In this specification, "low environmental impact" can be evaluated based on the proportion of paraformaldehyde remaining at the end of the reaction process. The less paraformaldehyde remaining at the end of the reaction process, the lower the environmental impact. In addition, "low environmental impact" also means that less solvent is required to produce a benzoxazine compound.

<1-1. Reaction process>
This production method includes a reaction step of heating a mixture of (A) phenol, (B) an amine composition containing a diamine represented by the above general formula (1), and (C) paraformaldehyde to cause the mixture to react with each other.

The above reaction process is carried out, for example, by mixing the raw materials (A) phenol, (B) the amine composition, and (C) paraformaldehyde to form a mixture, which is then placed in a three-neck flask or the like and heated.

In the above reaction step, when the amine composition (B) consists of only diamine, the molar ratio of (A) phenol:the diamine:(C) paraformaldehyde is preferably 2:1:4 to 2:1:6. If the molar ratio is in the above range, the product yield is excellent. Here, when the amine composition (B) contains a monoamine, 2 moles of monoamine are converted to 1 mole of diamine, and the number of moles of the diamine and monoamine are added together to calculate the molar ratio. In addition, the order of addition of the amine composition may be such that the diamine and monoamine are added simultaneously and reacted, or the monoamine is added first and the diamine is added after partial reaction. When the monoamine is added first, the generation of gel due to the reaction between the diamine and paraformaldehyde can be suppressed.

In the above reaction process, the heating temperature is preferably 90°C or higher, more preferably 100°C or higher, even more preferably 120°C or higher, and most preferably 130°C or higher. If the temperature during the heating reaction is 80°C or higher, it can exceed the melting point of the diamine used in this production method, making it possible to melt the diamine, thereby improving the efficiency of the reaction process. The upper limit of the temperature during the heating reaction is not particularly limited, but may be, for example, 250°C or lower.

In the above reaction step, the heating time is preferably 5 hours or less, more preferably 4 hours or less, even more preferably 3 hours or less, and most preferably 2 hours or less. If the time for carrying out the above reaction step is within the above range, the time is shorter than that of conventional manufacturing methods, and the production efficiency of benzoxazine-based compounds is improved. The lower limit of the heating time is not particularly limited as long as the raw materials can be sufficiently heated and reacted, but may be, for example, 20 minutes or more.

The method for determining the heating time in the reaction process is not particularly limited, but for example, it can be determined based on the consumption amount of the raw material (A) phenol. When the heating time is determined based on the consumption amount of (A) phenol, the heating time may be the time when it is predicted that 90% or more of (A) phenol is consumed. The consumption amount of (A) phenol can be measured by 1H-NMR.

In the reaction step, it is preferable to heat and stir the mixture. Stirring can be performed, for example, by using a stirring blade, a magnetic stirrer, or a shaker, but is not limited to these.

The mixture may be preheated before carrying out the reaction step. Preheating facilitates dispersion of (A) phenol and (B) the amine composition containing the diamine. The preheating temperature is not particularly limited, but may be, for example, about 30 to 70°C.

In the reaction step of this manufacturing method, the SC is more than 80% by weight and less than 100% by weight, more preferably 85 to 99% by weight, and most preferably 90 to 98% by weight. In this specification, "solid content concentration (SC)" refers to the proportion of solid matter in the mixture in this manufacturing method, assuming that (B) the amine composition containing the diamine, (A) phenol, and (C) paraformaldehyde are all solid. In the reaction step of this manufacturing method, if the SC is 80% by weight or more, the raw materials become highly concentrated, so the time required for the reaction is shortened and the yield of the obtained benzoxazine compound is improved. In the reaction step of this manufacturing method, the SC can be adjusted, for example, by adding a solvent to the mixture.

In the reaction step of the present manufacturing method, the mixture preferably contains a solvent (D) having a boiling point of 100°C or higher in an amount of more than 0% by weight and less than 20% by weight. The amount of the solvent (D) used is more preferably 1 to 15% by weight, and even more preferably 2 to 10% by weight. If the amount of the solvent (D) used is less than 20% by weight, the raw materials become highly concentrated, so the time required for the reaction is shortened and the yield of the obtained benzoxazine-based compound is improved. In addition, if the amount of the solvent (D) used is more than 0% by weight, the following advantages are obtained. For example, it is possible to use raw materials that do not melt at the reaction temperature of a normal melting method (a manufacturing method that does not use a solvent), that is, raw materials with a high melting point. In addition, in the melting method, each raw material melts, but when combined, it becomes a heterogeneous phase, so that there may be raw materials that do not react easily. If the amount of the solvent used is more than 0% by weight, such a combination of raw materials can also be used.

The boiling point of the solvent (D) is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher. If the boiling point of the solvent (D) is within the above range, the solvent (D) in the reactants does not evaporate during the heating reaction, and the solvent (D) continues to exist in the reactants, resulting in excellent reaction stability.

The above solvent (D) may be either an organic solvent or an aqueous solvent, but from the viewpoint of the boiling point mentioned above, it is preferable that it is an organic solvent.

The solvent (D) may be, for example, one or more selected from the group consisting of N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), 1,4-dioxane, toluene, n-butyl acetate, and diethyl carbonate. Among these, it is preferable that the solvent (D) is NMP in view of its high solubility in the raw materials.

(Diamine)
The amine composition (B) used in the present production method contains a diamine represented by the following general formula (1).

In formula (1), R1 is represented by the following general formula (2):

In formula (2), L1 and L3 are O, L2 is any one of O, C=O, _SO2 , C( _CH3 ) ₂ , C( _CF3 ) ₂ , or _CH2 , and p, q, r, s, and t are 0 or 1, provided that p+q+r+s+t≧1, and when s=0, p or q is 0, and when t=0, q or r is 0.

The above diamine may have an amino group in the para, ortho, or meta position relative to R1. The amino groups may have the same or different coordinate positions relative to R1. That is, for example, both amino groups may be in the para position relative to R1, or one amino group may be in the meta position and the other amino group in the para position. Of these, it is preferable that both amino groups are in the para position relative to R1, both amino groups are in the meta position relative to R1, or one amino group is in the meta position and the other amino group is in the para position. It is more preferable that both amino groups are in the para position relative to R1, or one amino group is in the meta position and the other amino group is in the para position. Furthermore, it is most preferable that both amino groups are in the para position relative to R1.

In the above formula (2), the positions of L1, L2, and L3 are not particularly limited. That is, as in the case of formula (1), L1 and L3 may be in the para position, ortho position, or meta position relative to L2.

In the above formula (2), p to t are 0 or 1. The parts of p to t where the value is 0 form a single bond between carbon atoms. That is, for example, when q is 0, the carbon atoms of the benzene rings on both sides of L2 form a single bond. In this case, the coordination is not particularly limited. That is, the benzene ring to which L3 is bonded may be in the para position, ortho position, or meta position relative to L1. Also, in the above formula (2), p+q+r+s+t≧1. That is, p to t are not all 0. That is, the benzene rings in the above formula (1) are not directly bonded to each other.

In the above formula (2), when s = 0, p or q is 0. When t = 0, q or r is 0. In other words, L1 (ether bond) and L2 are not consecutive, and L2 and L3 (ether bond) are not consecutive.

The diamine preferably has a melting point of 60°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher. If the diamine has a melting point within the above range, it has excellent reactivity, and therefore the production efficiency of the benzoxazine compound is improved. The upper limit of the melting point of the diamine is not particularly limited, but in reality it may be 250°C or lower.

Specifically, the diamine may be one or more selected from the following compounds:

1,3-bis(4-aminophenoxy)benzene [RODA] (formula (3) below, melting point: 115.0-119.0°C)

3,4'-Diaminodiphenyl ether [3,4'-ODA] (formula (4) below, melting point: 67-71°C)

3,3'-Methylenedianiline [3,3'-MDA] (formula (5) below, melting point: 82.0-85.0°C)

4,4'-Methylenedianiline [4,4'-MDA] (formula (6) below, melting point: 91.0-94.0°C)

1,3-bis(3-aminophenoxy)benzene [TPE-M] (formula (7) below, melting point: 107.0-109.0°C)

2,2-bis[4-(4-aminophenoxy)phenyl]propane [BAPP] (formula (8) below, melting point: 128.0-131.0°C)

4,4'-Diaminodiphenyl ether [4,4'-ODA] (formula (9) below, melting point: 190.0-194.0°C)

4,4'-bis(4-aminophenoxy)biphenyl [BAPB] (formula (10) below, melting point: 196.0-200.0°C)

4,4'-bis(3-aminophenoxy)biphenyl [3,3'-BAPB] (formula (11) below)

3,3'-Diaminobenzophenone [3,3'-DABP] (formula (12) below, melting point: 149.0-156.0°C)

4,4'-Diaminobenzophenone [4,4'-DABP] (formula (13) below, melting point: 245.0-249.0°C)

3,3'-sulfonyldianiline [3,3'-DDS] (formula (14) below, melting point: 170-173°C)

4,4'-sulfonyldianiline [4,4'-DDS] (formula (15) below, melting point: 175-177°C)

Bis[4-(4-aminophenoxy)phenyl]sulfone [BAPS] (formula (16) below)

Among the above-mentioned compounds, the diamine is preferably 1,3-bis(4-aminophenoxy)benzene (RODA) from the viewpoints of ease of handling due to the melting point of the raw material being between 100°C and 250°C, stability and reactivity of the resulting benzoxazine-based compound, and heat resistance and mechanical properties of the cured product obtained from it.

(Monoamines)
In the present production method, when a monoamine is used, for example, an aromatic monoamine such as aniline, toluidines, xylidines, ethylanilines, ethynylanilines, chloroanilines, bromoanilines, nitroanilines, aminophenols, aminocresols, aminobenzyl alcohols, anisidines, phenetidines, aminobenzaldehydes, aminobenzonitriles, aminobiphenyls, aminophenyl phenyl ethers, aminobenzophenones, aminophenyl phenyl sulfides, aminophenyl phenyl sulfones, naphthylamines, amino-naphthols, aminoanthracenes, etc., can be used. There is no particular limitation on the melting point, etc.

Among these, aniline or ethynylanilines are preferred from the viewpoints of ease of handling, stability and reactivity of the resulting benzoxazine-based compound, and heat resistance and mechanical properties of the cured product obtained from it. When the monoamine is an ethynylaniline, it is expected that the thermal properties of the cured product will be further improved by thermal crosslinking of the ethynyl moiety.

(others)
In this production method, the (A) phenol is a monophenol having only one hydroxy group bonded to the benzene ring.

Furthermore, (C) paraformaldehyde can be represented by the following general formula (17).

<1-2. Purification process＞
The present production method may further include a purification step of washing the product when the SC of the product is less than 100% by weight at the time when the reaction step is completed. The purification step is carried out to remove the solvent contained in the product.

In the purification step, the liquid for washing the product is not particularly limited, but may be, for example, water, an alkaline solution, and/or an acidic solution. The alkaline solution is not particularly limited, but may be, for example, an aqueous NaOH solution. The acidic solution is not particularly limited, but may be, for example, an aqueous HCl solution. Any solution may be used for washing, and the order of washing is not particularly limited. That is, for example, washing with an alkaline solution may be followed by washing with water, or washing with water may be followed by washing with an alkaline solution. Also, washing with an alkaline solution may be followed by washing with an acidic solution. Among these, washing with an alkaline solution or washing with water is preferred, and a combination of washing with an alkaline solution and washing with water is more preferred.

Before carrying out the purification step, the product obtained in the reaction step may be diluted with a solvent such as chloroform. The solvent used for dilution can be removed by distillation under reduced pressure after the purification step is completed.

<1-3. Others>
The present production method may be a method for producing a benzoxazine compound, comprising a reaction step of heating and reacting a mixture of (A1) a monophenol-based composition containing phenol, (B1) an amine-based composition containing a diamine and an optional monoamine, and (C) paraformaldehyde, or a mixture of (A2) a phenol-based composition containing bisphenol, (B2) a monoamine-based composition containing aniline, and (C) paraformaldehyde, wherein the SC of the mixture is 80 to 100% by weight.

In the reaction step of this manufacturing method, the SC is more preferably greater than 80% and less than 100% by weight, even more preferably 85-99% by weight, and most preferably 90-98% by weight.

<1-3-1>
The case where a mixture of (A1), (B1) and (C) is used will be described below.

In the reaction step of this production method, when the SC is 100% by weight, the monophenol-based composition containing phenol (A1) preferably consists of phenol alone. Also, when the SC is 80% by weight or more but less than 100% by weight, the monophenol-based composition containing phenol (A1) preferably contains 51 to 100% by weight of phenol and 49 to 0% by weight of a monophenol other than phenol, preferably contains 70 to 100% by weight of phenol and 30 to 0% by weight of a monophenol other than phenol, more preferably contains 80 to 100% by weight of phenol and 20 to 0% by weight of a monophenol other than phenol, and most preferably contains 90 to 100% by weight of phenol and 10 to 0% by weight of a monophenol other than phenol.

The monophenols other than phenol mentioned above are those having one or more phenolic hydroxyl groups on the aromatic ring, such as cresols, 3-methoxyphenols, 4-ethoxyphenols, fluorophenols, fluorocresols, ethynylphenols, cyanophenols, hydroxybenzaldehydes, dimethylphenols, ethylphenols, hydroxybenzyl alcohols, hydroxybenzenethiols, chlorophenols, allylphenols, naphthols, nitronaphthols, and hydroxypyrene, and there are no particular restrictions on the melting point. Among these, ethynylphenols are preferred from the viewpoints of handling, stability and reactivity of the resulting benzoxazine-based compound, and heat resistance and mechanical properties of the cured product obtained therefrom. When the monophenol is ethynylphenol, it is expected that the thermal properties of the cured product will be further improved by thermal crosslinking of the ethynyl moiety.

The conditions for using (A1) a monophenol-based composition containing phenol and (B1) an amine-based composition containing a diamine and an optional monoamine, as well as the SC and heating conditions in the reaction process, are as described in [1. Method for producing benzoxazine-based compounds].

<1-3-2>
The use of a mixture of (A2), (B2) and (C) is described below.

In this manufacturing method, when only bisphenol is used as the phenolic composition containing bisphenol (A2), the molar ratio of bisphenol:aniline and monoamine:paraformaldehyde is preferably 1:2:4 to 1:2:6. Here, when the phenolic composition containing bisphenol (A2) contains a monophenol, 2 moles of monophenol are converted to 1 mole of bisphenol, and the number of moles of monophenol and bisphenol are added together to calculate the molar ratio.

(monophenol)
(A2) The phenolic composition containing bisphenol contains 30 to 100% by weight of bisphenol and 70 to 0% by weight of monophenol, preferably contains 50 to 100% by weight of bisphenol and 50 to 0% by weight of monophenol, and more preferably contains 70 to 100% by weight of bisphenol and 30 to 0% by weight of monophenol.

When bisphenol is used in this manufacturing method, for example, 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A), bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, 2,2-bis(4-hydroxy-1-methylphenyl)propane, 1,1-bis(4-hydroxy-t-butylphenyl)propane, 2,2-bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxy-t-butylphenyl)propane, 1,1-bis(4-hydroxyphenyl)methane ... bis(hydroxyaryl)alkanes such as 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3-chlorophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, and 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane; bis(hydroxyaryl)alkanes such as 2,2-bis(4-hydroxyphenyl)phenylmethane and bis(4-hydroxyphenyl)naphthylmethane; bis(hydroxyaryl)cycloalkanes such as 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, and 1,1-bis(4-hydroxyphenyl)-3,5,5-trimethylcyclohexane; dihydroxyaryl ethers such as 4,4'-dihydroxyphenyl ether and 4,4'-dihydroxy-3,3'-dimethylphenyl ether; dihydroxydiaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide; dihydroxydiaryl sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide; dihydroxydiaryl sulfones such as 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone; and dihydroxydiphenyls such as 4,4'-dihydroxydiphenyl. Among these, bisphenol A is preferred from the standpoints of ease of handling due to the melting point of the raw material being between 100°C and 250°C, the stability and reactivity of the resulting benzoxazine-based compound, and the heat resistance and mechanical properties of the cured product obtained from it.

The monophenols mentioned above are those having one or more phenolic hydroxyl groups on the aromatic ring, such as phenol, cresols, 3-methoxyphenols, 4-ethoxyphenols, fluorophenols, fluorocresols, ethynylphenols, cyanophenols, hydroxybenzaldehydes, dimethylphenols, ethylphenols, hydroxybenzyl alcohols, hydroxybenzenethiols, chlorophenols, allylphenols, naphthols, nitronaphthols, and hydroxypyrene, and there are no particular restrictions on the melting point. Among these, phenol or ethynylphenols are preferred from the viewpoints of handling, stability and reactivity of the resulting benzoxazine-based compound, and heat resistance and mechanical properties of the cured product obtained therefrom. In the case of ethynylphenol, it is expected that the thermal properties of the cured product will be further improved by thermal crosslinking of the ethynyl moiety.

(B2) The monoamine composition containing aniline contains 51 to 100% by weight of aniline and 49 to 0% by weight of a monoamine other than aniline, preferably 70 to 100% by weight of aniline and 30 to 0% by weight of a monoamine other than aniline, more preferably 80 to 100% by weight of aniline and 20 to 0% by weight of a monoamine other than aniline, and most preferably 90 to 100% by weight of aniline and 10 to 0% by weight of a monoamine other than aniline.

The monoamines other than aniline include aromatic monoamines such as toluidines, xylidines, ethylanilines, ethynylanilines, chloroanilines, bromoanilines, nitroanilines, aminophenols, aminocresols, aminobenzyl alcohols, anisidines, phenetidines, aminobenzaldehydes, aminobenzonitriles, aminobiphenyls, aminophenyl phenyl ethers, aminobenzophenones, aminophenyl phenyl sulfides, aminophenyl phenyl sulfones, naphthylamines, amino-naphthols, and aminoanthracenes, and there are no particular restrictions on the melting point. Among these, ethynylanilines are preferred from the viewpoints of handling, stability and reactivity of the obtained benzoxazine-based compound, and heat resistance and mechanical properties of the cured product obtained therefrom. When the monoamine is ethynylanilines, it is expected that the thermal properties of the cured product will be further improved by thermal crosslinking of the ethynyl moiety.

2. Benzoxazine Compounds
The benzoxazine compound produced by the present production method (hereinafter also referred to as the present benzoxazine compound) is a compound represented by the following formula (17).

In the above formula (17), R1 is determined by the diamine used as the raw material. In other words, it can be said that R1 is represented by the above formula (2). For example, when 1,3-bis(4-aminophenoxy)benzene represented by formula (3) is used as the above diamine, a benzoxazine-based compound represented by the following general formula (18) is obtained.

The glass transition temperature (Tg) of the present benzoxazine-based compound is preferably 110°C or higher, more preferably 120°C or higher, and even more preferably 130°C or higher. If the Tg of the present benzoxazine-based compound is 110°C or higher, the present benzoxazine-based compound can be said to have excellent heat resistance. There is no particular upper limit to the Tg, but in reality it may be 300°C or lower. In this specification, "glass transition temperature (Tg)" means the temperature at which the cured product of the present benzoxazine-based compound, which is cured by heating, undergoes glass transition.

The curing temperature (Tc) of the present benzoxazine-based compound is preferably 270°C or less, more preferably 260°C or less, and even more preferably 250°C or less. If the Tc of the present benzoxazine-based compound is 270°C or less, it becomes easy to produce a cured product from the present benzoxazine-based compound. In this specification, "curing temperature (Tc)" means the temperature at which the uncured present benzoxazine-based compound is cured by heating.

The 5% weight loss temperature (Td5) of the present benzoxazine-based compound is preferably 290°C or higher, more preferably 300°C or higher, and even more preferably 310°C or higher. If the present benzoxazine-based compound has a temperature of 290°C or higher, it can be said that the present benzoxazine-based compound has excellent heat resistance. In this specification, the "5% weight loss temperature (Td5)" refers to the temperature at which the present benzoxazine-based compound undergoes thermal decomposition and loses 5% weight, measured in an environment in which the uncured present benzoxazine-based compound is cured.

The benzoxazine compound can be suitably used in electronic components, laminates for printed wiring boards and printed wiring boards, semiconductor encapsulation materials, electronic materials such as semiconductor-mounted modules, automobiles or vehicles, aircraft parts, building materials, machine tools, etc. Among these, it can be used particularly in parts that require heat resistance.

Specifically, for example, when used as a molding material for the above-mentioned parts or as a semiconductor encapsulation material, the present benzoxazine-based compound can be used as is, or can be used with the addition of fillers, release agents, flame retardants, colorants, coupling agents, etc., as necessary. In addition, a prepreg for laminates can be produced by adding a solvent or the like to the present benzoxazine-based compound to form a varnish, impregnating a substrate such as glass cloth with this, and heating and drying it. Furthermore, a laminate for printed wiring boards can be produced by heating and pressing this prepreg together with metal foil, and further forming a circuit on the laminate, thereby producing a printed wiring board. The printed wiring board produced in this way has excellent heat resistance and mechanical properties, and is therefore suitable for use as a semiconductor mounting substrate, etc.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in different embodiments.

The following examples and comparative examples are presented to explain the present invention, but are not intended to limit the present invention. First, the methods for measuring each physical property are as follows.

[Measurement method]
1. Glass Transition Temperature (Tg)
The powder-shaped uncured product was subjected to differential scanning calorimetry (DSC) using a differential scanning calorimeter DSC7000X (manufactured by Hitachi High-Tech). Specifically, the DSC curve was measured under conditions of a nitrogen gas flow (40 mL/min) and a temperature rise rate of 10°C/min. The temperature at the intersection of the tangent at the inflection point of the obtained DSC curve and the baseline was taken as Tg. The value of the 2nd scan of DSC was used as Tg.

(2. Curing temperature (Tc))
Tc was calculated in the same manner as Tg, except that the values from the first scan were used for DSC.

(3. Thermal decomposition temperature (Td5))
The powder-shaped uncured product was evaluated for 5% weight loss temperature (Td5) at a heating rate of 10°C/min by thermogravimetric analysis (TGA) using Hitachi High-Tech's TG/DTA6300. Note that the Td5 value was measured using differential thermal analysis (TG-DTA) under a _N2 gas flow.

Example 1
2.193 g (0.0075 mol) of 1,3-bis(4-aminophenoxy)benzene, 1.412 g (0.015 mol) of phenol, and 1.081 g (0.036 mol) of paraformaldehyde were placed in a three-neck flask, heated and stirred at 130°C, and reacted for 30 minutes. The heating time was determined based on the time at which the consumption rate of the raw material phenol reached approximately 93%, as calculated by 1H-NMR. Since no solvent was used, the solid content (SC) was set to 100% by weight.

After the heating reaction, 80 ml of chloroform was added to dissolve the product. After that, the mixture was washed three times with 80 ml of 1N NaOH aqueous solution and three times with 80 ml of pure water, and the solvent in the chloroform layer was distilled off under reduced pressure at 40°C. The mixture was then vacuum dried at 60°C for six hours to obtain a powder of the benzoxazine compound of the above formula (18).

The molecular weight of the resulting benzoxazine compound powder was measured by GPC, and the number average molecular weight (Mn) was 930 and the weight average molecular weight (Mw) was 1,752, calculated in terms of standard polystyrene.

Example 2
2.193 g (0.0075 mol) of 1,3-bis(4-aminophenoxy)benzene, 1.412 g (0.015 mol) of phenol, 1.081 g (0.036 mol) of paraformaldehyde, and 0.247 g of N-methylpyrrolidone were placed in a three-neck flask, heated and stirred at 130°C, and reacted for 60 minutes. The heating time was determined in the same manner as in Example 1. The solid content (SC) was calculated based on the assumption that all of the diamine, phenol, and aldehyde had become solid. SC was 95% by weight.

After the reaction, 30 ml of chloroform was added to dilute the product, and the product was washed five times with 30 ml of pure water. After that, the product was washed three times with 30 ml of 1N NaOH aqueous solution and three times with 30 ml of pure water, and the solvent in the chloroform layer was distilled off under reduced pressure at 40°C. The product was then vacuum dried at 60°C for six hours to obtain a powder of the benzoxazine compound of the above formula (18).

The molecular weight of the resulting benzoxazine compound powder was measured by GPC, and the number average molecular weight (Mn) was 859 and the weight average molecular weight (Mw) was 1947, calculated in terms of standard polystyrene.

Example 3
2.193 g (0.0075 mol) of 1,3-bis(4-aminophenoxy)benzene, 1.412 g (0.015 mol) of phenol, 1.081 g (0.036 mol) of paraformaldehyde, and 1.172 g of N-methylpyrrolidone were charged into a three-neck flask, and the mixture was heated and stirred at 130° C. to react for 120 minutes. The heating time was determined in the same manner as in Example 1. The solid content (SC) was calculated in the same manner as in Example 2. SC was 80% by weight.

After the reaction, 30 ml of chloroform was added to dilute the product, and the product was washed five times with 30 ml of pure water. Then, the product was washed three times with 100 ml of 1N NaOH aqueous solution and three times with 100 ml of pure water. Next, the product was washed three times with 100 ml of 0.1N HCl aqueous solution, and then washed three times with 100 ml of pure water, and the solvent in the chloroform layer was distilled under reduced pressure at 40°C. Then, the product was vacuum dried at 60°C for 6 hours to obtain a powder of the benzoxazine compound of the above formula (18).

The molecular weight of the resulting benzoxazine compound powder was measured by GPC, and the number average molecular weight (Mn) was 1,325 and the weight average molecular weight (Mw) was 5,215, calculated in terms of standard polystyrene.

Comparative Example 1
2.195 g (0.0075 mol) of 1,3-bis(4-aminophenoxy)benzene, 1.413 g (0.015 mol) of phenol, 2.925 g (0.036 mol) of 37% formalin, and 1.285 g of ethyl acetate were placed in a three-neck flask, and the mixture was heated and stirred at 80° C. to react for 25 hours. The heating time was determined in the same manner as in Example 1. The solid content (SC) was calculated in the same manner as in Example 2. SC was 60% by weight.

After the reaction, 80 ml of chloroform was added to dilute the product, which was then washed three times with 80 ml of 1N NaOH aqueous solution and three times with 40 ml of pure water. The chloroform layer was then distilled under reduced pressure at 40°C to remove the solvent. The mixture was then vacuum dried at 60°C for six hours to obtain a powder of the benzoxazine compound of the above formula (18).

The molecular weight of the resulting benzoxazine compound powder was measured by GPC, and the number average molecular weight (Mn) was 980 and the weight average molecular weight (Mw) was 2029, calculated in terms of standard polystyrene.

〔result〕
Table 1 shows the heating conditions during the reaction in Examples 1 to 3 and Comparative Example 1, and the results of evaluating the thermal properties of the obtained powder of the benzoxazine compound of formula (18) by DSC and TGA.

From Table 1, it was found that the heating times of Examples 1 to 3, in which the SC was 80 to 100% by weight, were much shorter than the heating time of Comparative Example 1, in which the SC was 60% by weight. It was also found that the benzoxazines of Examples 1 to 3 had equivalent performance in Tg, Tc, and Td5 compared to the benzoxazine of Comparative Example 1 obtained by the conventional solution method. Therefore, it was shown that this manufacturing method can produce benzoxazine-based compounds in a shorter time than the conventional manufacturing method.

The present invention can be suitably used as a method for producing benzoxazine-based compounds.

Claims (9)

A reaction process for reacting a mixture of (A) phenol, (B) an amine composition containing a diamine represented by the following general formula (1) and an optional monoamine, and (C) paraformaldehyde, by heating the mixture, wherein the solid content of the mixture is 80 % by weight or more and less than 100% by weight ,
The method for producing a benzoxazine-based compound , wherein the mixture contains more than 0 wt % of (D) a solvent having a boiling point of 100° C. or higher .

In formula (1), R1 is represented by the following general formula (2).

In formula (2), L1 and L3 are O (ether bond), L2 is any one of O (ether bond), C=O, _SO2 , C( _CH3 ) ₂ , C( _CF3 ) ₂ , or _CH2 , and p, q, r, s, and t are 0 or 1, provided that p+q+r+s+t≧1, and when s=0, p or q is 0, and when t=0, q or r is 0. The method for producing a benzoxazine compound according to claim 1, wherein the heating temperature in the reaction step is 90°C or higher. The method for producing a benzoxazine compound according to claim 1 or 2, wherein the heating time in the reaction step is 5 hours or less. A method for producing a phenol-based composition comprising: (A) a phenol; (B) an amine-based composition comprising a diamine represented by the following general formula (1) and an optional monoamine; and (C) paraformaldehyde; wherein the mixture has a solid content of more than 80% by weight and less than 100% by weight,
The mixture contains (D) a solvent having a boiling point of 100° C. or higher in an amount of more than 0% by weight and less than 20% by weight .

In formula (1), R1 is represented by the following general formula (2).

In formula (2), L1 and L3 are O (ether bond), L2 is any one of O (ether bond), C=O, SO2 _, C(CH3 ₎ 2 _, C( _CF3 ) ₂ , or CH2 , and _p , q, r, s, and t are 0 or 1, provided that p+q+r+s+t≧1, and when s=0, p or q is 0, and when t=0, q or r is 0. The method for producing a benzoxazine compound according to claim 4, wherein the solvent (D) is at least one selected from the group consisting of N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), 1,4-dioxane, toluene, n-butyl acetate, and diethyl carbonate. The method for producing a benzoxazine compound according to any one of claims 1 to 5, further comprising a purification step of washing the product if the solids concentration of the product is less than 100% by weight at the end of the reaction step. The method for producing a benzoxazine compound according to any one of claims 1 to 6, wherein the melting point of the diamine is 60°C or higher. The method for producing a benzoxazine compound according to any one of claims 1 to 7, wherein the diamine is one or more selected from the compounds represented by the following formulas (3) to (16):

The present invention includes a reaction step of heating and reacting a mixture of (A1) a monophenol-based composition containing phenol, (B1) an amine-based composition containing a diamine and an optional monoamine, and (C) paraformaldehyde, or a mixture of (A2) a phenol-based composition containing bisphenol, (B2) a monoamine-based composition containing aniline, and (C) paraformaldehyde, wherein the solid content of the mixture is 80 % by weight or more and less than 100% by weight ,
The method for producing a benzoxazine-based compound , wherein the mixture contains more than 0 wt % of (D) a solvent having a boiling point of 100° C. or higher .