JP2011184552A - Thermosetting resin solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosetting resin solution that stably exists in the state of a solution for a long time, and is excellent in storage stability, and a cured body (molded body) that has higher rigidity and glass transition temperature than the hitherto typical benzoxazine B-a cured body. <P>SOLUTION: The thermosetting resin solution includes a triazacyclic compound having a phenolic hydroxide group, an epoxy compound, and a polar medium. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a novel thermosetting resin solution that can obtain a highly rigid resin by thermosetting after drying.

Benzoxazine is known to be a thermosetting resin that is thermoset by ring-opening polymerization, and Patent Document 1 describes in detail the synthesis of benzoxazine and the evaluation of the polymer. This document describes that benzoxazine is synthesized from a phenol component, an amine component and formaldehyde.
On the other hand, Non-Patent Document 1 discloses another method for producing benzoxazine. In the method described in this document, first, a compound having a triaza ring (1,3,5-triphenylhexahydro-1,3,5-triazine) obtained by mixing aniline and formaldehyde (hereinafter referred to as hexahydro A compound having a -1,3,5-triazine ring is abbreviated as “triaza ring compound”). Next, by reacting the triaza ring compound with bisphenol A, a typical benzoxazine monomer (6,6 '-(1-methylethyliden) bis (3,4-dihydro-3-phenyl-2H-1) , 3-benzoxazine) (hereinafter abbreviated as “Ba”).

JP 49-47378 A

Zdenka Brunovska, Macromol. Chem. Phys. Vol. 200, p.1745-1752 (1999)

However, in the methods described in the above-mentioned documents, the triaza ring compound and the phenol compound are likely to react with each other, and it is difficult for both to coexist. In the following formula (2), an example of a reaction in which a triaza ring compound and a phenol compound react to form a benzoxazine ring is shown.
Formula (2):

As is apparent from the above reaction formula, the compound represented by the following formula (1) having a phenolic hydroxyl group in the triaza ring compound has low storage stability, and will be thermally cured when stored for a long period of time. There's a problem.
Formula (1):

  Moreover, the resin composition using the conventional benzoxazine monomer (Ba) still has room for improvement from the viewpoint of rigidity and glass transition temperature.

  In view of the above circumstances, an object of the present invention is to provide a thermosetting resin solution that can exist stably in a solution state for a long period of time and has excellent storage stability. Furthermore, it aims at providing the hardening body (molded object) which has high rigidity and a high glass transition temperature compared with the conventional hardening body of typical benzoxazine Ba.

  As a result of intensive studies on the above problems, the present inventors have found that a triaza ring compound having a phenolic hydroxyl group, a polar solvent for stabilizing the compound, and an epoxy compound for further improving the crosslinking density, It has been discovered that a novel thermosetting resin solution containing, exists stably for a long time in the solution state. Furthermore, after removing (drying) the solvent of the thermosetting resin solution, it was found that a cured product having extremely high rigidity and a high glass transition temperature can be obtained by thermosetting, thereby completing the present invention. It was.

That is, the present invention is as follows.
[1]
A thermosetting resin solution containing a triaza ring compound having a phenolic hydroxyl group, an epoxy compound, and a polar solvent.
[2]
The thermosetting resin solution according to the above [1], wherein the triaza ring compound is a compound represented by the following formula (1).
Formula (1):

[3]
The thermosetting resin solution according to [1] or [2], wherein the solid content concentration of the thermosetting resin solution is 10% by mass or more and 50% by mass or less.
[4]
The thermosetting resin solution according to any one of the above [1] to [3], wherein the epoxy compound is blended in an amount of 1 to 3.5 mole equivalent as an equivalent of an epoxy group with respect to 1 mole equivalent of the triaza ring compound. .
[5]
The hardening body obtained by thermosetting the thermosetting resin solution in any one of said [1]-[4].

ADVANTAGE OF THE INVENTION According to this invention, the novel thermosetting resin solution excellent in storage stability can be provided.
The cured product obtained by thermosetting the thermosetting resin solution of the present invention has a high rigidity and a high glass transition temperature as compared with a conventional resin composition using benzoxazine Ba. Have.

The NMR chart of the triaza ring compound obtained in Example 1 is shown.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. However, the present invention is not limited to the following embodiment, and various modifications can be made without departing from the gist of the present invention.

  The thermosetting resin solution of this embodiment contains a triaza ring compound having a phenolic hydroxyl group, an epoxy compound, and a polar solvent.

  The thermosetting resin solution of the present embodiment is a liquid having a very low viscosity at room temperature (20 ° C. ± 15 ° C.) (100 cps or less). For this reason, the impregnation to a reinforced fiber etc. is very easy. The molded product obtained by drying and heat-curing the thermosetting resin solution of the present embodiment is excellent in heat resistance and mechanical strength. Therefore, electrical / electronic parts, automobile parts, copper-clad laminates, printed boards, fire resistance It can be suitably used for coating, composite matrix resin and the like.

(Triaza ring compound)
The triaza ring compound having a phenolic hydroxyl group in the present embodiment can be obtained by reacting an amine containing a phenolic hydroxyl group with formaldehyde.

  Examples of the amine containing a phenolic hydroxyl group include 2,6-dichloro-4-aminophenol, 2-amino-4-chlorophenol, o-aminophenol, m-aminophenol, p-aminophenol, and the like. Among these, p-aminophenol is particularly preferable because of excellent heat resistance and low cost.

  By mixing formaldehyde and p-aminophenol in a solvent, the triaza ring compound represented by the above formula (1) can be easily obtained. Although this reaction proceeds even at room temperature, it is preferably heated to 50 ° C. or higher from the viewpoint of synthesis in a shorter time.

(Polar solvent)
The “polar solvent” in this embodiment refers to a solvent having a dielectric constant of 5 or more. For example, since the dielectric constant of toluene is 2.4 and the dielectric constant of chloroform is 4.8, it is not included in the “polar solvent” defined in this embodiment.

  By using a polar solvent, the stability of the triaza ring compound containing a phenolic hydroxyl group can be improved. In chloroform, the triaza ring compound represented by the above formula (1) not only has low solubility but also decomposes to cause a conversion reaction to a benzoxazine ring.

  Examples of polar solvents that can be used in this embodiment include methanol, ethanol, tetrahydrofuran, pyridine, 1-propanol, 1,4-dioxane, cyclohexanone, ethyl acetate, n-propyl acetate, n-butyl acetate, and ethyl lactate. , Ethyl cellosolve, propylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether, methyl cellosolve, 1-methyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, n, n-dimethylacetamide, acetone, acetonitrile, methyl ethyl ketone, methyl isobutyl ketone, etc. be able to. Among these, acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, methyl cellosolve, ethyl cellosolve, and dimethylformamide are particularly preferable because they easily dissolve the triaza ring compound and the epoxy compound and have a relatively low boiling point.

(Epoxy compound)
In the thermosetting resin solution of this embodiment, an epoxy compound is blended for the purpose of improving the crosslinking density when the solvent is dried and then thermoset.

  Examples of the epoxy compound include glycidyl ether type epoxy resins (bisphenol A type, bisphenol F type), glycidyl ester type epoxy resins, polyfunctional epoxy resins, polymer type epoxy resins, biphenyl type epoxy resins, and the like. Among these, from the viewpoint of obtaining a higher crosslinking density, a polyfunctional epoxy resin containing three or more epoxy functional groups is particularly preferable.

  The thermosetting resin solution of the present embodiment includes three components, the above-described triaza ring compound, epoxy compound, and polar solvent. Hereinafter, each composition ratio is demonstrated.

For example, when the triaza ring compound represented by the above formula (1) is thermally cured, it is expected that polymerization represented by the following formula (3) occurs.
Formula (3):

  As shown in the above formula (3), in the polymer after polymerization, one primary amine group and one secondary amine group are generated. There is a possibility that the crosslinking reaction proceeds. Therefore, the epoxy compound is preferably added in an amount of 1 to 3.5 molar equivalents, more preferably 2 to 3 molar equivalents of the epoxy group based on 1 molar equivalent of the triaza ring compound. The crosslink density is improved, and the rigidity and glass transition temperature tend to be more remarkably improved. If the content of the epoxy compound is less than 1 molar equivalent as the equivalent of the epoxy group, the crosslinking density may be insufficient and the rigidity and heat resistance of the cured product may be inferior. The ratio of the epoxy compound increases too much, and there is a possibility that the cured body is inferior in rigidity and heat resistance.

For polar solvents, if the solid content concentration of the thermosetting resin solution is defined as follows,
“Solid content concentration (mass%) = mass of triaza ring compound + mass of epoxy compound / mass of solution”
It is preferable to blend the polar solvent so that the solid content concentration is preferably 10% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 30% by mass or less. Here, if the solid content concentration exceeds 50% by mass, the storage stability after long-term storage may be lowered, and if it is less than 10% by mass, the solvent cost may increase.

  Regarding the storage stability of the resin solution, it is necessary that the viscosity of the solution during storage does not increase remarkably or gelation does not occur. Specifically, it is preferable that the viscosity increase of the solution when stored at room temperature (23 ° C.) for 10 days is at least 50% or less.

  Although it does not specifically limit as a shaping | molding method to the product of the thermosetting resin solution of this embodiment, For example, after casting a thermosetting resin solution, a solvent is removed by drying and then the temperature of 120-200 degreeC. A method of obtaining a molded body (cured body) by heating and curing for 30 minutes to 2 hours.

  Since the molded product obtained by drying and thermoforming the thermosetting resin solution of the present embodiment is excellent in heat resistance and mechanical strength, electrical / electronic parts, automobile parts, copper-clad laminates, printed boards, fire resistance It can be suitably used for coating, composite matrix resin and the like.

  Hereinafter, the present embodiment will be described in more detail with reference to examples. However, the present embodiment is not limited to the examples described below.

[Measuring method]
The physical property measurement method and measurement conditions in this example are as follows.
(1) Proton nuclear magnetic resonance spectrum (1H-NMR spectrum)
JEOL Ltd., model number JNM-ECX, 1H-NMR (400 MHz)
Measurement was performed using deuterium chloroform, 256 times integration, and relaxation time of 10 seconds.

(2) Glass transition temperature Dynamic viscoelasticity measuring device (DMA) manufactured by SII, model number DMS6100
Tensile mode (10Hz)
The measurement was performed in air and the glass transition temperature was determined from the tan δ peak.

(3) Tensile strength and tensile modulus Instron universal test equipment (Model 5565)
Sample piece (TypeV ASTM D6-38-03)
Measurement was performed at a pulling speed of 1 mm / min.

(4) Viscosity Viscosity was measured using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[Example 1]
(Production of triaza ring compound represented by formula (1))
Formula (1):

A 50 cc round bottom flask equipped with a reflux condenser was charged with 2 g of 4-aminophenol (Wako Pure Chemicals, 015-02692), 1.6 g of 37% by weight formaldehyde (Wako Pure Chemicals, 064-00406), tetrahydrofuran (Japanese (7) Light pure drug product, 200-00486) 7 g was added and stirred, the temperature of the oil bath was raised to 90 ° C., the reaction was continued for 10 minutes while refluxing the solvent, and then cooled to room temperature.
A part of this solution was taken and an NMR chart was obtained using DMSO (d-6) as a solvent (FIG. 1). As a result, a sharp peak of the methylene group of the triaza ring was observed in the vicinity of 4.55 ppm, and no other large peak was observed. Therefore, it was judged that the reaction was completed within the above reaction time.
The mass of the triaza compound contained in this solution is estimated to be approximately 2.2 g assuming that the reaction has progressed 100%. This is about 6 mmol in terms of mole.

(Preparation of epoxy compound)
As a polyfunctional epoxy resin, 2 g of tetrahydrofuran (Wako Pure Chemicals, 200-00486) was added to 2 g of Epicron HP4700 (DIC Corporation, Epoxy Equivalent 162) and dissolved with stirring. This is about 12 mmol in terms of moles of epoxy group.

(Preparation of a mixed solution of triaza ring compound, epoxy resin, and tetrahydrofuran (THF))
A thermosetting resin solution was prepared by mixing and stirring the respective solutions prepared above. The solid content concentration of the obtained resin solution was approximately 29% by mass. Furthermore, when the viscosity of this resin solution was measured, it was 9 cps (mPa) (centipoise).
When the viscosity of this resin solution after storage for 10 days in a thermostatic chamber set at 23 ° C. is 12 cps, a slight increase in viscosity is observed, but there is no abnormality such as gelation and it can be used for molding. Met.

(Production of sheet)
The above resin solution was poured into a Teflon (registered trademark) petri dish and dried at room temperature all day and night. Then, it was further dried for 5 hours in a heating oven set to 60 ° C. The temperature of the hot air oven was raised to 180 ° C., and heat curing was performed by heating for 30 minutes to obtain a sheet having a thickness of 0.1 mm. The tensile properties and glass transition temperature of this sheet were measured. The measurement results are shown in Table 1.

[Comparative Example 1]
In order to compare the glass transition point, benzoxazine Ba (product of Shikoku Kasei Co., Ltd.) was evaluated.

(Production of sheet)
The benzoxazine Ba was thickened by placing it in a heated press controlled to a temperature of 220 ° C. that had been subjected to a mold release treatment and left for 5 minutes. Next, a heat curing treatment was performed at a pressure of 10 gf / cm ² for 30 minutes, and then cooled to form a sheet having a thickness of 0.1 mm.
The tensile properties and glass transition temperature of the obtained sheet were measured. The measurement results are shown in Table 1.
As is clear from the results in Table 1, the cured product of Comparative Example 1 is inferior to the cured product of the Examples in terms of tensile strength, tensile modulus, and glass transition temperature. It can be said that the cured product produced from the resin solution is superior to the cured product obtained by curing the conventional benzoxazine resin.

[Comparative Example 2]
In Example 1, the step of mixing the solution in which the epoxy compound was dissolved was omitted, and only the triaza ring compound was cured to produce a cured body. The same method as in Example 1 was used as a method for creating the sheet.
The tensile properties and glass transition temperature of the obtained sheet were measured. The measurement results are shown in Table 1.
As is clear from the results in Table 1, the cured product of Comparative Example 2 is inferior to the cured product of the Examples in terms of tensile strength, tensile modulus, and glass transition temperature. It can be seen that the epoxy compound in the resin solution plays a large role in improving physical properties.

[Example 2]
By evaporating THF as a solvent from the resin solution prepared in Example 1, the solid content concentration was increased to 60% by mass. At this time, the viscosity of the resin solution was measured and found to be 15 cps. After storing this solution in a temperature-controlled room set at 23 ° C. for 10 days, the viscosity is measured to be 110 cps, an increase in viscosity is seen compared to the initial state, and storage stability may be inferior after long-term storage. It became clear. From this, it can be seen that making the solid content concentration of the resin solution too high (concentration exceeding 50% by mass) adversely affects the storage stability after long-term storage.

  Since the molded product obtained by drying and thermoforming the thermosetting resin solution of the present embodiment is excellent in heat resistance and mechanical strength, electrical / electronic parts, automobile parts, copper-clad laminates, printed boards, fire resistance Industrial applicability to coatings, composite matrix resins, etc.

Claims (5)

  A thermosetting resin solution containing a triaza ring compound having a phenolic hydroxyl group, an epoxy compound, and a polar solvent. The thermosetting resin solution according to claim 1, wherein the triaza ring compound is a compound represented by the following formula (1).
Formula (1):
  The thermosetting resin solution of Claim 1 or 2 whose solid content concentration of the said thermosetting resin solution is 10 mass% or more and 50 mass% or less.   The thermosetting resin solution according to any one of claims 1 to 3, wherein the epoxy compound is blended in an amount of 1 to 3.5 mole equivalent as an equivalent of an epoxy group with respect to 1 mole equivalent of the triaza ring compound.   The hardening body obtained by thermosetting the thermosetting resin solution of any one of Claims 1-4.