JPH0920816A - Production of thermosetting compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a thermosetting compound by reacting a phenol novolak resin with a primary amine and formaldehyde in an organic solvent, reducing the viscosity of a reactional solution and stably carrying out the uniform reaction without forming a volatile by-product at the time of curing reaction. SOLUTION: A primary amine in an amount of 0.2-0.9mol based on 1mol hydroxyl group in a phenol novolak resin is reacted with formaldehyde in a molar amount of >=2 times based on 1mol hydroxyl group in the phenol novolak resin in an organic solvent such as ethyl acetate, butyl acetate, methyl ethyl ketone or toluene to afford a thermosetting compound having two or more dihydrobenzoxazine rings in one molecule.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a novel thermosetting compound which hardly produces a volatile by-product during a curing reaction.

[0002]

Thermosetting resins such as phenolic resins, epoxy resins, unsaturated polyester resins and bismaleimide resins are widely used in many industrial fields due to their reliability characteristics such as heat resistance and electric insulation. However, phenolic resin has volatile by-products when cured, epoxy resin and unsaturated polyester resin have inferior heat resistance and flame retardancy, and bismaleimide resin is very expensive. . Therefore, in order to solve these problems, development of a new thermosetting resin has been conventionally advanced. One of them is a thermosetting compound containing a dihydrobenzoxazine ring (JP-A-49-47378, US Pat. No. 5).
152939). Further, as a compound and a manufacturing method in which the physical properties and reaction conditions thereof are further developed, the present inventors have found that a compound having two or more hydroxylphenylene groups in which at least one ortho-position of the hydroxyl group is hydrogen in one molecule and a primary The amine and formaldehyde are added in an amount of 0.2 to 10 parts by weight of primary amine to 1 mol of the hydroxyl group in which at least one of the ortho positions of the hydroxylphenylene group is hydrogen.
A method was proposed in which 0.9 mol and formaldehyde were mixed in a ratio of at least twice the molar amount of primary amino and reacted at the reflux temperature. (Japanese Patent Application No. 5-330157) Furthermore, in U.S. Pat. No. 4,561,864, a solvent is added to the reaction system to suppress a side reaction, and after the reaction, stationary separation, vacuum distillation and cooling solidification are carried out by a batch operation to obtain a desired amount. Those that try to obtain a thermosetting compound have been proposed.

[0003]

However, this compound has a faster curability than known thermosetting compounds, and therefore it is extremely difficult to carry out a reaction operation with excellent productivity, and the following problems occur during mass production. That is, the thermosetting resin targeted by the present invention partially undergoes polymerization as a side reaction during the synthetic reaction for forming the oxazine ring, and therefore the viscosity of the reaction solution increases. Specifically, as in Example 1 shown in Japanese Patent Application No. 5-330157, a novolac resin is used as a compound containing a hydroxyphenylene group, which is mixed with aniline and dropped into formalin. When the reaction temperature is maintained at the reflux temperature and the reaction proceeds, the viscosity of the reaction solution rapidly increases as shown in FIG. This increase in viscosity causes non-uniform stirring, which causes quality variations and the like, and it is difficult to quickly cool and stop the reaction at the reaction end point, and sometimes the reaction product may gel.

[0004]

In order to solve such a problem, the present inventors have found that the following manufacturing method can solve such a problem, and have reached the present invention. That is, the present invention is characterized in that 0.2 to 0.9 mol of a primary amine and 2 times or more mol of formaldehyde as a primary amine are reacted with 1 mol of a hydroxyl group of a phenol novolac resin in an organic solvent. .

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a solvent for dissolving a compound is added in advance to a reaction system for carrying out ring-opening polymerization, and synthesis is promoted by heating and stirring below the reflux temperature of the solvent. After completion of the synthesis, solid or liquid resin is stably produced by continuously removing the solvent from the reaction system by applying mechanical operation or thermal operation. As the solvent to be added, ethyl acetate,
It is more preferable that the solvent has a small solubility in water, such as MEK (methyl ethyl ketone) and toluene. The phenol novolac resin used in the present invention is not particularly limited and ordinary phenol novolac resin and modified resins thereof can be used. As the primary amine, an amine having an aromatic ring is preferable because it has excellent heat resistance. By adding a solvent that dissolves the compound to the reaction system, the viscosity of the reaction solution can be reduced, which enables uniform stirring and also reduces the film resistance of the boundary surface that controls the heat transfer ability. Further, the monomer concentration of the reaction system is diluted and the reaction rate is suppressed. As a result of these, the reaction can be stably progressed, and the reaction can be stopped by rapidly cooling at the reaction end point. Further, the present compound contained in the reaction system has low solubility in water. Therefore, by using a solvent having a low water-solubility as the solvent for dissolving the resin, most of the water contained in the reaction system can be removed by a mechanical separation method such as static separation or centrifugation. Hereinafter, the present invention will be described more specifically with reference to examples.

[0006]

【Example】

[Example 1] (1) Synthesis of novolak resin as compound containing hydroxyphenylene group Since novolak resin is used as compound containing hydroxyphenylene group, 1.9 kg of phenol, 1.0 kg of formalin (37% aqueous solution), oxalic acid 4 g was charged in a 5 liter flask and reacted at reflux temperature for 6 hours. Subsequently, the pressure inside the flask was reduced to 666 Pa or less to perform dehydration and removal of unreacted phenol. The obtained resin has a softening point of 8
The peak area ratio by gel permeation chromatography at 4 ° C. is 3 to polynuclear body / 2 binuclear body ratio (82/18)
Met. The molecular weight distribution curve of the obtained novolak resin is shown in FIG. (2) Introduction of dihydrobenzoxazine ring 1.7 kg (corresponding to 16 mol of hydroxyl group) of the novolak resin synthesized above was added to 0.93 kg (1
0 mol) and MEK 0.72 kg (42 wt% of novolac) were mixed and dissolved to prepare a uniform solution. Charge 1.62 kg of formalin into a 5 liter flask 80
The mixture was heated to 0 ° C., and the novolak aniline solution was added thereto over 30 minutes. After completion of the addition, the reaction was further allowed to proceed at the reflux temperature for 180 minutes, and then the reaction solution was rapidly cooled to stop the reaction. The reaction solution viscosity at the end of the reaction was 2.5 Pa · s. (3) Solidification of thermosetting compound 1) Separation of resin component of reaction system After the reaction was stopped, the reaction liquid was allowed to stand for 30 minutes, and the resin layer and the water layer were separated.
After separating the layers, the lower resin layer was taken out to obtain a solution thermosetting compound in which 71% of reactive hydroxyl groups were dihydrobenzoxazinized. 2) Solidification of thermosetting compound To solidify the solution thermosetting compound obtained above, a spray dryer having a sprayer for atomizing the solution and a chamber for contacting with hot air for drying is used. Then, the solvent was dried and removed by contact with hot air at 120 ° C. The obtained resin is a solid resin having an average particle diameter of 80 μm and a residual volatile content of 5% or less and having a high fluidity. Further, when this solid resin was dried for 90 minutes by a fluid dryer having an air temperature of 75 ° C., a solid resin having a residual volatile content of 2% or less was obtained.

[Example 2] (1) A novolac resin was synthesized in the same manner as in [Example 1]. (2) Introduction of dihydrobenzoxazine ring Toluene was used instead of MEK used in (2) of [Example 1]. The compounding amount was 0.72 kg, the same amount as the novolak resin, the dropping time was 30 minutes, and the reaction temperature was 100 ° C. The reaction was stopped 100 minutes after reaching 100 ° C. to obtain a liquid thermosetting resin. (3) Solidification of thermosetting compound 1) Separation of resin component in reaction system After the reaction is stopped, the reaction liquid is supplied to a liquid / liquid continuous centrifuge with a centrifugal force of 3000 G, and the resin layer is separated from the water layer to form a liquid. To obtain a thermosetting resin. In order to solidify the solution-type thermosetting compound obtained above, a continuous vacuum evaporator consisting of a heat evaporation pipe with a shucket, an evaporator for separating solid matter and vapor, and a condenser for condensing vapor was used at 6400 Pa. The solvent was evaporated and dried under reduced pressure and at a heating medium temperature of 130 ° C. The obtained resin is a solid resin having a residual volatile content of 5% or less.

[Example 3] (1) A novolac resin was synthesized in the same manner as in [Example 1]. (2) Introduction of dihydrobenzoxazine ring In place of MEK used in (2) of [Example 1], ethyl acetate was used. The compounding amount was 0.72 kg, the same amount as the novolak resin, the dropping time was 30 minutes, and the reaction temperature was 80 ° C. The reaction was stopped 180 minutes after reaching 80 ° C.
Temperature is 50 ° C. (3) Solidification of thermosetting compound 1) Separation of resin component of reaction system The obtained compound is cooled to a liquid temperature of 50 ° C. and allowed to stand still, and after 60 minutes, a resin layer is separated from an aqueous layer. A liquid thermosetting resin was obtained. 2) Solidification of thermosetting compound In order to solidify the solution thermosetting compound obtained above, a continuous vacuum evaporator consisting of a vacuum vacuum chamber with a shacket, a belt conveyor for conveying the material to be dried, and a condenser is used. The solvent was evaporated under reduced pressure of 6500 Pa and the heat medium temperature of 120 ° C. to obtain a solid resin having a residual volatile content of 5% or less. Further, this resin is crushed to obtain a flat particle size of 50 μm.
After the following, the product was fluidized and dried at an air temperature of 75 ° C. for 100 minutes to obtain a solid resin having a residual volatile content of 2% or less. This molecular weight distribution curve is shown in FIG.

[Example 4] (1) A novolak resin was synthesized in the same manner as in [Example 1]. (2) Introduction of dihydrobenzoxazine ring In place of MEK used in (2) of [Example 1], butyl acetate was used. The compounding amount was 0.72 kg, the same amount as the novolak resin, the dropping time was 30 minutes, and the reaction temperature was 90 ° C. The reaction was stopped 150 minutes after reaching 90 ° C. (3) Solidification of thermosetting compound 1) Separation of resin component of reaction system The obtained compound was cooled to a liquid temperature of 50 ° C. and then allowed to stand,
After 60 minutes, the resin layer was separated from the water layer to obtain a liquid thermosetting resin. 2) Solidification of thermosetting compound In order to solidify the solution thermosetting compound obtained above, nitrogen heated at 140 ° C. was blown using a spray dryer to dry and remove the solvent. The obtained resin was a granular resin having an average particle diameter of 80 μm, which had a smaller hue than that of [Example 1], and the residual volatile content was 3% or less.

Example 5 Xylylene-modified phenol resin (trade name; Milex XL-225-3L, Mitsui Toatsu Chemicals, Inc.) 1.7 kg (hydroxyl group 10 mol)
(Corresponding) and aniline 0.52 kg (5.6 mol) formalin 0.91 kg in the same manner as in Example 1 to synthesize a novolac resin.

Example 6 A mixture of 0.7 kg of aniline and 0.27 kg of toluidine was used in place of aniline,
A thermosetting compound having a dihydrobenzoxazine ring introduced was obtained in the same manner as in [Example 1] below.

Comparative Example 1 (1) A novolak resin was synthesized in the same manner as in [Example 1]. (2) Introduction of dihydrobenzoxazine ring 1.7 kg of the novolak resin synthesized above and 0.93 kg of aniline were mixed and dissolved to prepare a uniform solution. Charge 1.62 kg of formalin into a 5 liter flask 10
The temperature was raised to 0 ° C., and a mixed solution prepared in advance was added dropwise thereto. At the same time as the dropping, the surroundings of the dropping liquid boiled, so it took 60 minutes to complete the dropping. In the state of the reaction system, the viscosity increases 15 minutes after the start of dropping and rises to 700 Pa · s 30 minutes after reaching the reflux temperature, and it is difficult to discharge it from the flask because it adheres to the stirring blade and the fluidity is significantly reduced. Met.

Comparative Example 2 (1) A novolak resin was synthesized in the same manner as in [Example 1]. (2) Introduction of dihydrobenzoxazine ring 1.7 kg (corresponding to 16 mol of hydroxyl group) of the novolak resin synthesized above was added to 0.93 kg (1
0 mol) and MEK 0.72 kg (42 wt% of novolac) were mixed and dissolved to prepare a uniform solution. 5
Charge 1.62 kg of formalin into a liter flask 8
Heat to 0 ° C and add novolac aniline solution to it 30 times.
Added over minutes. After completion of the addition, the reaction was further allowed to proceed at the reflux temperature for 180 minutes, and then the reaction solution was rapidly cooled to stop the reaction.
The reaction solution viscosity at the end of the reaction was 2.5 Pa · s. (3) Solidification of thermosetting compound 1) Separation of resin component of reaction system The obtained compound was cooled to a liquid temperature of 50 ° C. and then allowed to stand,
After 60 minutes, the resin layer was separated from the water layer to obtain a liquid thermosetting resin. 2) Solidification of thermosetting compound In order to solidify the solution thermosetting compound obtained above, vacuum distillation was performed under a reduced pressure of 6500 Pa, and the solvent started to flow out from the reaction vessel. The liquid also thickened and could not be stirred, and gelled before discharging.

[0014]

INDUSTRIAL APPLICABILITY According to the present invention, the viscosity of the reaction solution can be lowered by adding a solvent that dissolves the compound to the reaction system, and a uniform reaction can be stably proceeded.

[Brief description of drawings]

FIG. 1 is a diagram showing how the viscosity of a solventless reaction system increases.

2 is a molecular weight distribution curve of the phenol novolac resin of Example 1. FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuyuki Hirai 1500 Ogawa, Shimodate City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Shimodate Factory

Claims (4)

[Claims] 1. A feature of reacting 0.2 to 0.9 mol of a primary amine and 2 times or more mol of formaldehyde of a primary amine in an organic solvent with respect to 1 mol of a hydroxyl group of a phenol novolac resin. A method for producing a thermosetting compound having two or more dihydrobenzoxazine rings in one molecule. 2. The method for producing a thermosetting compound having a dihydrobenzoxazine ring according to claim 1, wherein the organic solvent is selected from the group consisting of ethyl acetate, butyl acetate, methyl ethyl ketone and toluene. 3. The water is removed from the reaction solution containing the thermosetting compound by mechanical operation.
Or a method for producing a thermosetting compound having a dihydrobenzoxazine ring according to 2 above. 4. The method for producing a thermosetting compound having a dihydrobenzoxazine ring according to claim 1, wherein the solvent is continuously removed from the reaction solution containing the thermosetting compound by a thermal operation. .