JP2002338648A - Method for producing heat-curing resin having benzoxazine ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a heat-curing resin having a benzoxazine ring which does not enlarge a molecular weight to bring about an insoluble matter during the synthetic reaction and needs neither an apparatus nor a complicated process for adding an amine little by little to suppress heat generation. SOLUTION: The method for producing a heat-curing resin having a benzoxazine ring comprises a process for reacting a phenol, paraformaldehyde and an amine in an organic solvent, wherein the organic solvent is an aprotic solvent (excluding dioxane); and the phenol and the amine are dissolved in the aprotic solvent followed by adding a lump of the total paraformaldehyde necessary for the reacting into the reacting system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermosetting resin having a benzoxazine ring. More specifically, the present invention is a sealing material, impregnation, laminate,
Adhesive, paint, coating material, friction material, whetstone, FRP
(Fiber-reinforced plastic) and a method for producing a thermosetting resin having a benzoxazine ring that can be used for a molding material and the like.

[0002]

2. Description of the Related Art In a thermosetting resin having a benzoxazine ring in a structure, an oxazine ring is opened by heating, and polymerization proceeds without generation of by-products. Laminates, adhesives, paints, coatings,
Attention has been drawn to thermosetting resins used for friction materials, grindstones, FRP, molding materials, and the like. The benzoxazine ring is a composite structure of a benzene ring and an oxazine ring,
The structure is represented by the following general formula (I).

[0003]

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(Wherein R ¹ is an alkyl group, an aralkyl group, a phenyl group, or a phenyl group having an alkyl or alkoxyl group as a substituent)

[0005] The production method of these thermosetting resins having a benzoxazine ring includes phenols, amines,
A method for producing a compound by reacting with formaldehyde is known (JP-A-49-47378 and JP-A-20-47378).
00-273135).

The resin (polymerizable product) disclosed in JP-A-49-47378 is manufactured by simultaneously adding phenol and amine to formaldehyde (formalin). However, when a thermosetting resin having a benzoxazine ring is produced using formalin as a formaldehyde source, there is a problem that the production becomes difficult because the molecular weight increases during the synthesis reaction and the resin becomes insoluble.

In the method for producing a phenolic resin disclosed in Japanese Patent Application Laid-Open No. 2000-273135, amines are added to a solution in which a phenol and paraformaldehyde are suspended in an organic solvent in order to suppress heat generation. Is added little by little. However, equipment such as a dropping pump for adding the amines little by little as in this production method, or complicated steps such as charging a small number of times many times are required. A method is desired.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a facility for adding amines little by little so that the molecular weight does not increase during the synthesis reaction and insolubilization is prevented, and heat generation is suppressed. An object of the present invention is to provide a method for producing a thermosetting resin having a benzoxazine ring, which does not require a step.

[0009]

Means for Solving the Problems The present inventors have made intensive studies and as a result have found that the above problems can be solved.

That is, the present invention relates to a method for producing a thermosetting resin having a benzoxazine ring, comprising the step of reacting phenols, paraformaldehyde and amines in an organic solvent, wherein the organic solvent is an aprotic solvent. (Excluding dioxane), and dissolving the phenols and amines in the aprotic solvent, and then adding the entire amount of paraformaldehyde necessary for the reaction to the reaction system at once. An object of the present invention is to provide a method for producing a thermosetting resin having an oxazine ring.

Further, the present invention is characterized in that the phenol is a monofunctional phenol, a polyfunctional phenol, or a mixture of a monofunctional phenol and a polyfunctional phenol. It is intended to provide a method for producing a curable resin.

Further, the present invention provides a thermosetting resin having a benzoxazine ring, wherein the aprotic solvent is one or more selected from aromatic solvents, ketone solvents and ester solvents. A method for producing a resin is provided.

The present invention also provides a method for producing the above-mentioned thermosetting resin having a benzoxazine ring, wherein the amount of the aprotic solvent is 30 to 200% by weight of the phenol.

[0014]

DETAILED DESCRIPTION OF THE INVENTION The phenols used in the present invention are monofunctional phenols, polyfunctional phenols,
Alternatively, a mixture of a monofunctional phenol and a polyfunctional phenol may be used. The above monofunctional phenols and polyfunctional phenols may be used alone or as a mixture of two or more.

The monofunctional phenols need only have at least one active hydrogen at the ortho position to the hydroxy group, and include, for example, phenol, o-cresol, m-
Cresols such as cresol and p-cresol; 2,3
-Xylenols such as xylenol, 2,4-xylenol, 2,5-xylenol, 3,4-xylenol and 3,5-xylenol; ethylphenols such as o-ethylphenol, m-ethylphenol and p-ethylphenol. Butylphenols such as n-butylphenol, s-butylphenol and t-butylphenol;
Alkylphenols such as trimethylphenols such as 2,3,4-trimethylphenol, 2,3,5-trimethylphenol, 2,4,5-trimethylphenol and 3,4,5-trimethylphenol; o-phenylphenol, m Arylphenols such as -phenylphenol and p-phenylphenol; aralkylphenols such as o-benzylphenol, m-benzylphenol and p-benzylphenol; o-vinylphenol, m-vinylphenol, p-vinylphenol and o
Alkenyl phenols such as -allylphenol, m-allylphenol, p-allylphenol; o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, o-ethoxyphenol, m-ethoxyphenol, p-ethoxyphenol and the like Alkoxyphenols; halogenated phenols such as o-chlorophenol, m-chlorophenol, p-chlorophenol; monofunctional phenols such as naphthols such as α-naphthol and β-naphthol; However, the present invention is not limited to this.

Polyfunctional phenols include, for example, biphenol, dihydroxydiphenyl ether, dihydroxybenzophenone, isopropylidenebisphenol, ethylidenebisphenol, methylenebisphenol, cyclohexylidenebisphenol, 1-phenylethylidenebisphenol, phenylmethylenebisphenol,
Bisphenols having at least one active hydrogen ortho to one hydroxyl group such as sulfonylbisphenol and methylenebis-4-methylphenol; methylidenetrisphenol, ethylidenetrisphenol, 1- (4- ( At least ortho to one hydroxyl group such as 1- (4-hydroxyphenyl) -1-methylethyl) phenyl) ethylidene bisphenol, bis ((2-hydroxy-5-methylphenyl) -4-methyl) phenol Trisphenols having one or more active hydrogens; 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, 1,1,3,
3-tetrakis (4-hydroxyphenyl) propane,
Tetrakisphenols having at least one active hydrogen ortho to one hydroxyl group such as 1,1,5,5-tetrakis (4-hydroxyphenyl) pentane; phenol novolak resin, cresol novolak resin Novolak resins such as isopropylidene bisphenol novolak resin; modified phenol resins such as xylylene-modified phenol resin, dicyclopentadiene-modified phenol resin, butadiene-modified phenol resin, melamine-modified phenol resin, and guanamine-modified phenol resin; polyhydroxystyrenes; Catechol, resorcin, hydroquinone, pyrogallol, and the like can be shown, but are not limited thereto. Among them, preferred are phenol and cresols as monofunctional phenols, phenol novolak resin, methylene bisphenol, isopropylidene bisphenol as polyfunctional phenols, and mixtures of these monofunctional phenols and polyfunctional phenols.

The amines used in the present invention include monofunctional amines or polyfunctional amines, and mixtures of monofunctional amines and polyfunctional amines. Also,
The above monofunctional amines and polyfunctional amines may be used alone or in combination of two or more.

These amines include, for example, aliphatic amines such as methylamine, cyclohexylamine, ethylenediamine, hexamethylenediamine, and aromatic amines such as aniline, toluidine, benzylamine, bromoaniline, anisidine, xylidine, phenylenediamine and diaminoamine. Diphenyl ether, diaminobenzophenone,
Examples thereof include amines such as diaminodiphenylmethane and diaminodiphenylsulfone, but are not limited thereto. Among them, aniline and triidine are preferable.

As the paraformaldehyde used in the present invention, commercially available paraformaldehyde can be used. It is preferable that the concentration of paraformaldehyde is 92% by weight or more, because the molecular weight during the synthesis reaction becomes high and insolubilization is suppressed.

The organic solvent used in the present invention is preferably an aprotic solvent, for example, an aromatic solvent such as benzene, toluene and xylene; a ketone solvent such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ethyl acetate and acetic acid Examples thereof include ester solvents such as butyl, but are not limited thereto. However, the use of dioxane is not used in the production method of the present invention, because the molecular weight of the resin may increase during the synthesis reaction and the resin may be insolubilized. Further, the aromatic solvent, ketone solvent,
The ester solvents may be used alone or as a mixture of two or more.

The amount of the aprotic solvent to be used is preferably 30 to 200% by weight based on phenols, and is preferably 40 to 200% by weight.
150% by weight is more preferred, and 50 to 100% by weight is most preferred. If the amount of the solvent used is less than 30% by weight of the phenols, it tends to be difficult to control the heat of reaction during the synthesis reaction. On the other hand, when the amount of solvent used is 2
If it exceeds 00% by weight, the time and cost for removing the organic solvent tend to be large.

The method for producing a thermosetting resin having a benzoxazine ring according to the present invention comprises the step of reacting a phenol, paraformaldehyde and an amine in an organic solvent. In the above, after the organic solvent is an aprotic solvent (however, excluding dioxane), and after dissolving the phenols and amines in the aprotic solvent,
It is characterized in that the entire amount of paraformaldehyde required for the reaction is added all at once to the reaction system. At that time, if the phenols, amines and paraformaldehyde are used in such a ratio that 1 mole of amino group and 2 moles of formaldehyde are used for 1 mole of phenolic hydroxyl group, 1 mole of benzoxazine ring is formed. The phenolic hydroxyl groups can also be made excessive.

The addition of paraformaldehyde is preferably carried out when the solution of phenols and amines in an aprotic solvent has a temperature in the range of 20 to 50 ° C., preferably 35 to 45 ° C. When the temperature of the solution in which the phenols and amines are dissolved in the aprotic solvent exceeds 50 ° C., it tends to be difficult to control the heat of reaction. On the other hand, cooling the solution to less than 20 ° C.
It is not preferable because the energy required for cooling increases.

After completion of the introduction of paraformaldehyde, the temperature is raised to a desired reaction temperature, and heating is continued to react paraformaldehyde. Thereafter, the temperature is further increased, heating is continued for about 1 to 10 hours, and then the pressure and the pressure are reduced to remove the solvent and the generated moisture, whereby a transparent resinous substance can be obtained. The resinous material is sampled and the viscosity at 50 ° C. (using a B-type viscometer)
Alternatively, by terminating the reaction when the melt viscosity at 150 ° C. (using an ICI viscometer) reaches a predetermined value,
A thermosetting resin having a benzoxazine ring is obtained.

The resin obtained by the method for producing a thermosetting resin having a benzoxazine ring of the present invention comprises a curing accelerator, a flame retardant, an inorganic filler, a release agent, an adhesion-imparting agent, a surfactant, a coloring agent. An agent may be added for use.

[0026]

The present invention will be described in more detail with reference to the following synthesis examples and working examples, which should not be construed as limiting the scope of the present invention.

Synthesis Example of Phenol Novolak Resin A 500 g of phenol, 125 g of 37% by weight formalin,
1 g of oxalic acid was charged into a 1 liter flask and reacted at a reflux temperature for 6 hours. Subsequently, water and unreacted phenol were removed to obtain a resin. The obtained resin was designated as phenol novolak resin A.

Example 1 376 g of phenol (4 mol) was placed in a 2 liter flask.
l), 188 g of phenol novolak resin A (1.8
mol), 539 g (5.8 mol) of aniline and 280 g of methyl ethyl ketone were charged and dissolved to prepare a solution. The temperature of the solution was adjusted to 40 ° C., and 378 g (11.6 mol) of 92% by weight of paraformaldehyde were added. After completion of the addition, the mixture was heated to 60 ° C and reacted at 60 ° C for 1 hour, and further heated to 80 ° C and reacted at 80 ° C for 5 hours.
Thereafter, the solvent and the generated water were removed, and when the viscosity at 50 ° C. became 800 mPa · s with a B-type viscometer, the reaction was terminated and cooled. A thermosetting resin having a liquid benzoxazine ring was obtained without excessive heat generation during the heating and during the reaction.

Example 2 684 g (3 mol) of isopropylidenebisphenol and 558 g of aniline were placed in a 2-liter separable flask.
(6 mol) and 350 g of toluene were charged and dissolved to prepare a solution. The temperature of the solution was adjusted to 40 ° C., and 391 g (12 mol) of 92% by weight of paraformaldehyde was added. After completion of the addition, the mixture was heated to 60 ° C and reacted at 60 ° C for 1 hour, and further heated to 80 ° C and reacted at 80 ° C for 5 hours.
Thereafter, the solvent and generated water were removed, and the reaction was terminated when the melt viscosity at 150 ° C. became 0.2 Pa · s with an ICI viscometer, and the mixture was poured into a metal vat and cooled.
A thermosetting resin having a solid benzoxazine ring was obtained without excessive heat generation during the heating and during the reaction.

Example 3 600 g (3 mol) of methylene bisphenol and 558 g (6 mol) of aniline were placed in a 2-liter separable flask.
l), 400 g of ethyl acetate was charged and dissolved to prepare a solution. The temperature of the solution was adjusted to 40 ° C., and 391 g (12 mol) of 92% by weight of paraformaldehyde was added. After completion of the addition, the mixture was heated to 60 ° C and reacted at 60 ° C for 1 hour, and further heated to 80 ° C and reacted at 80 ° C for 5 hours. Thereafter, the solvent and generated water were removed, and the reaction was terminated when the melt viscosity at 150 ° C. became 0.2 Pa · s with an ICI viscometer, and the mixture was poured into a metal vat and cooled. A thermosetting resin having a solid benzoxazine ring was obtained without excessive heat generation during the heating and during the reaction.

Comparative Example 1 456 g of isopropylidenebisphenol (2 mol
l), 432 g (4 mol) of aniline was added to dioxane 30
A solution dissolved in 0 g was prepared. 648 g of 37% by weight formalin was charged into a 2-liter separable flask and heated to 90 ° C., and the above-mentioned solution of isopropylidenebisphenol and aniline dissolved in dioxane was added little by little. After the addition was completed, the reaction was carried out at reflux temperature for 2 hours. After the completion of the reaction, the viscosity of the resin increased during the removal of the solvent and water, and stirring became difficult, and the reaction was interrupted.

Comparative Example 2 In a 2-liter separable flask, 684 g (3 mol) of isopropylidene bisphenol and 450 parts of methanol were added.
g, 92% by weight of paraformaldehyde 391 g (12
mol)) to prepare a suspended solution. The temperature of the solution was adjusted to 40 ° C., and 648 g (4 mol) of aniline was added thereto all at once.

Comparative Example 3 684 g (3 mol) of isopropylidenebisphenol and 558 g of aniline were placed in a 2-liter separable flask.
(6 mol) and 350 g of dioxane were charged and dissolved to prepare a solution. The temperature of the solution was adjusted to 40 ° C. and 92% by weight
Of 391 g (12 mol) of paraformaldehyde was added. After completion of the addition, the mixture was heated to 60 ° C and reacted at 60 ° C for 1 hour, and further heated to 80 ° C and reacted at 80 ° C for 5 hours. Thereafter, during the removal of the solvent and the generated water, the viscosity of the resin increased, stirring became difficult, and the reaction was interrupted.

[0034]

According to the present invention, there is no need for equipment or a complicated process for adding amines little by little so that the molecular weight does not increase during the synthesis reaction and insolubilization does not occur, and heat generation is suppressed. A method for producing a thermosetting resin having a benzoxazine ring is provided.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Satoshi Ogawa 1040-2-405 Egicho, Takasaki-shi, Gunma F-term (reference) 4J033 FA02 FA04 FA11 HA12 HA28 HB03 HB04 HB06 HB08 HB09

Claims (4)

[Claims] 1. A method for producing a thermosetting resin having a benzoxazine ring, comprising a step of reacting phenols, paraformaldehyde and amines in an organic solvent, wherein the organic solvent is an aprotic solvent (provided that Dioxane), and dissolving the phenols and amines in the aprotic solvent, and then adding the whole amount of paraformaldehyde necessary for the reaction to the reaction system at once, to form a benzoxazine ring. A method for producing a thermosetting resin. 2. The phenols are monofunctional phenols,
The method for producing a thermosetting resin having a benzoxazine ring according to claim 1, wherein the method is a polyfunctional phenol or a mixture of a monofunctional phenol and a polyfunctional phenol. 3. The benzoxazine ring according to claim 1, wherein the aprotic solvent is at least one selected from an aromatic solvent, a ketone solvent, and an ester solvent. A method for producing a thermosetting resin. 4. The method for producing a thermosetting resin having a benzoxazine ring according to claim 1, wherein the amount of the aprotic solvent is 30 to 200% by weight of the phenol.