JPH0959334A - Thermosetting resin, its cured product and production of the same thermosetting resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new thermosetting resin having stable uniform composition and forming a high crosslinking density exceeding a conventional benzoxadine compound after polymerization. SOLUTION: Four components comprising a polyphenol compound, formaldehyde, at least one kind of a divalent primary amine compound and at least one kind of a monovalent primary amine compound are reacted in (1-3):(2-2.2):1 molar ratio of mol number of phenol nucleus of polyphenol compound: mol number of formaldehyde: total mol number of amino group of a divalent primary amine compound and amino group of a monovalent primary amine compound and (1:9) to (5:5) molar ratio of mol number of amino group of the divalent primary amine compound: mol number of amino group of the monovalent primary amine compound to provide the objective thermosetting resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel thermosetting resin improved to have a high-density crosslinked structure. Among thermosetting resins, electronic parts, automobile parts, which require particularly high reliability, The present invention relates to a thermosetting resin that is preferably used in information communication devices and structural members.

The present invention also relates to a suitable method for producing the thermosetting resin and a cured product obtained by curing the thermosetting resin.

[0003]

2. Description of the Related Art Thermosetting resins have higher reliability than thermoplastic resins due to their excellent properties such as heat resistance and dimensional stability, and are widely used in various industrial fields. This is largely due to the cross-linking structure peculiar to the curable resin, and particularly phenol resin, melamine resin and the like which have high heat resistance have a very high density cross-linking structure. However, such a high-density cross-linked structure also gives the cured resin a disadvantage of being brittle and poor in toughness.

On the other hand, for these general-purpose thermosetting resins,
Due to the rigidity of the resin unit structure itself, there are resins that exhibit high heat resistance even if the crosslink density is not large. For example, in recent years, JP-A-49-47378 discloses a compound having a dihydrobenzoxazine ring which can be polymerized by heating (hereinafter sometimes referred to as a dihydrobenzoxazine compound), and these are general-purpose thermosetting compounds described above. It has high heat resistance and mechanical strength comparable to the above-mentioned general-purpose thermosetting resins, even though the ratio of polymerization points is smaller than that of the thermosetting resin, that is, the crosslink density in the cured product is small.

[0005] If the dihydrobenzoxazine compound having excellent properties in spite of the low cross-linking density can be made to have a higher cross-linking density, higher heat resistance and mechanical strength can be expected, and the industrial application range thereof can be further expanded. However, it is very difficult to increase the crosslink density of the dihydrobenzoxazine compound. This is because the dihydrobenzoxazine ring has the disadvantage of being partially polymerized during synthesis, at the cost of its useful property that it can be easily polymerized by heating. If it is attempted to form, the side reaction causes gelation and cannot be a stable thermosetting resin. For this reason, for example, US Pat. No. 4,501,864 discloses a method for curing a dihydroenzoxazine compound, which is characterized by using a polyamine.
A method in which a compound containing a dihydrobenzoxazine ring at a low density and a polyamine are prepared as a composition and reacted at the time of polymerization without directly converting the amino group of the polyamine to dihydrobenzoxazine is used. Naturally, in this method, it is necessary to prevent the components in the composition from reacting with each other before the curing reaction and to keep them in a uniformly mixed state.
Depending on the kneading method used for preparing the composition, the filler, the third component, the solvent, etc., reaction between the components or phase separation may occur,
It is extremely difficult to achieve both control of reaction and prevention of phase separation.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a thermosetting resin having a novel dihydrobenzoxazine ring, which has a stable and uniform composition and, after polymerization, forms a high crosslink density superior to that of conventional dihydrobenzoxazine compounds. It is intended to provide a cured product thereof and a method for producing the thermosetting resin.

[0007]

Means for Solving the Problems In order to solve the above problems, the inventors of the present invention have conducted extensive studies and as a result, introduced a structure of a divalent amine compound into the molecule to cause gelation as shown below. It has been found that a thermosetting resin having a high-density benzoxazine ring can be produced without the need, and the present invention has been completed based on this finding.

That is, in the present invention, four components of a polyphenol compound, formaldehyde, at least one kind of divalent primary amine compound and at least one kind of monovalent primary amine compound are added to the polyphenol compound in the number of moles of phenol nucleus: formaldehyde. Molar number: The divalent primary amine compound has a molar ratio of 1 to 3: 2 to 2.2: 1 in terms of the total mole number of the amino group of the divalent primary amine compound and the amino group of the monovalent primary amine compound. The number of moles of amino groups of 1): a method for producing a thermosetting resin, characterized in that the number of moles of amino groups of a monovalent primary amine compound is reacted in a molar ratio of 1: 9 to 5: 5. is there.

The polymerization reaction of the compound having a dihydrobenzoxazine ring proceeds as shown in the following formula (1) for each dihydrobenzoxazine ring.

[0010]

Embedded image (In the formula, n represents the number of dihydrobenzoxazine rings.) Therefore, when a dihydrobenzoxazine compound is synthesized from a polyphenol compound, the cured product has a crosslinked structure even if all the amine compounds are monovalent. Therefore, when the above-mentioned side reaction occurs during the synthesis of the dihydrobenzoxazine compound from the polyphenol compound, a slight cross-linked structure is generated even before the curing, but this alone does not lead to gelation of the entire resin. However, if a divalent amine compound is used, the cross-linking structure generated by the polyphenol compound and the cross-linking due to the polyfunctionalization of the amine compound appear as a synergistic effect, and even if the synthesis is performed under mild conditions, gelation occurs rapidly during the synthesis. Occurs, and a polyfunctionalized dihydrobenzoxazine compound cannot be produced. Therefore, an important factor in the present invention is how many divalent amine compounds can be introduced into the polyphenol compound / monovalent amine system within a range that does not cause gelation.

[0011]

Specifically, the ratio of the number of moles of amino groups of a divalent primary amine compound to the number of moles of amino groups of a monovalent primary amine compound is such that the amino group of a divalent primary amine compound is :
The amino group of the monovalent primary amine compound needs to have a molar ratio of 1: 9 to 5: 5, and particularly preferably 2: 8 to 4: 6.

Further, since the degree of cross-linking is due to the synergistic effect of the polyfunctionality of the amine compound and the polyfunctionality of the phenol nucleus of the polyphenol compound, there is an appropriate range in the structure of the polyphenol compound. That is, as the polyphenol compound, bisphenol or formaldehyde and phenol are formaldehyde: phenol = 4 to 7:
It is preferable to use a phenol novolac resin obtained by reacting at a molar ratio of 10.

Specific examples of bisphenol include:

[0014]

Embedded image Etc. are used. Among them, bisphenol A is particularly preferable.

On the other hand, as the monovalent primary amine compound, for example, methylamine, cyclohexylamine, aniline, substituted aniline such as substituted aniline substituted with an alkyl group having 1 to 12 carbon atoms or an aryl group, and the like are used. From the viewpoint of the stability of the dihydrobenzoxazine ring and the heat resistance of the cured product, aniline is particularly preferable.

Further, as the divalent primary amine compound,

[0017]

Embedded image Etc. are used. Aromatic diamines are particularly preferable as in the case of monovalent primary amine compounds, and among them, p-phenylenediamine and 2,2-bis [4- (4-aminophenoxy) phenyl] propane are preferable.

As described above, the method for producing a thermosetting resin of the present invention has a raw material composition in which the suppression of gelation in the production process is particularly taken into consideration. By reacting these raw materials, the desired thermosetting resin is obtained. To manufacture. As a reaction method, specifically, a mixture of a polyphenol compound, a divalent primary amine compound and a monovalent primary amine compound is added to an aqueous solution of formaldehyde as it is or after it is dissolved in a solvent and added.
It is preferable to react at a temperature of 140 ° C for 20 minutes to 8 hours. If the reaction is carried out outside this range, or if the order of addition of the raw materials is changed, gelation may occur during production or a large amount of unreacted substances may remain.

Like the conventionally known dihydrobenzoxazine compound, the thermosetting resin of the present invention is cured only by heating without releasing volatile by-products. However, since a partially crosslinked structure is formed in the stage before curing, the fluidity at the time of curing is slightly inferior, and therefore, a curing method of press molding at high temperature is suitable. Specifically, 1
A desired cured product is produced by heating at 50 to 220 ° C. for 20 minutes to 2 hours.

The cured product has excellent properties such as high heat resistance, high strength, high elasticity and low dimensional change due to the action of the divalent primary amine compound. Is partly fixed.

[0021]

EXAMPLES The present invention will be specifically described below with reference to specific examples, but the present invention is not limited thereto.

Example 1 745 g of aniline (corresponding to 8 mol) and 108 g of p-phenylenediamine (corresponding to 1 mol) were mixed at 80 ° C. to form a uniform solution, and 1141 g of bisphenol A (corresponding to 5 mol) was added and further mixed to form a slurry. Got Separately 1623 g of formalin (37% aqueous solution) in a 3 liter flask
(Corresponding to 20 mol) was weighed and heated to 90 ° C., and the above slurry was added little by little over 20 minutes while stirring. After the addition, paying attention to heat generation, the inside of the flask was kept at 90 to 100 ° C., and after 30 minutes, the product was cooled and solidified, and the product was taken out on a vat. This was roughly crushed and dried under reduced pressure at 100 ° C. for 4 hours to obtain polyfunctional dihydrobenzoxazine 1. This polyfunctional dihydrobenzoxazine 1 was extracted with methyl ethyl ketone using a Soxhlet extractor, the residue was dried and weighed, and the ratio to the weight before extraction was determined as a gel fraction. The gel fraction is shown in Table 1. In the case of polyfunctional dihydrobenzoxazine 1, it was 0.02% or less.

This polyfunctional dihydrobenzoxazine 1 was crushed and filled in a mold of 100 × 100 × 4 mm, and heated and pressed under the conditions of 200 ° C., 30 minutes and 30 kgf / cm ² by a hydraulic press machine to obtain a plate-like shape. A molded product was obtained. This was appropriately cut and subjected to a characteristic test. Table 1 shows the characteristics of the cured product. Further, FIG. 1 shows an IR spectrum of this cured polyfunctional dihydrobenzoxazine 1.

Example 2 In the same manner as in Example 1, except that the amounts of aniline and p-phenylenediamine compounded were 559 g (corresponding to 6 mol) of aniline and 216 g (corresponding to 2 mol) of p-phenylenediamine, polyfunctional dihydrobenzoxazine 2 was similarly added. Was synthesized. However, in order to reduce the viscosity of the aniline / p-phenylenediamine / bisphenol A mixed slurry, ethanol 50
0 g was added. The gel fraction of this polyfunctional dihydrobenzoxazine 2 is shown in Table 1. Further, the polyfunctional dihydrobenzoxazine 2 was cured in the same manner as in Example 1. The characteristics of the cured product are shown in Table 1, and the IR spectrum of the cured product is shown in FIG.

Example 3 In place of the p-phenylenediamine of Example 2, 821 g (corresponding to 2 mol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane was used, and a polyfunctional dihydrobenzoxazine was similarly prepared. 3 was synthesized. However, aniline
In order to reduce the viscosity of the 2,2-bis [4- (4-aminophenoxy) phenyl] propane / bisphenol A mixed slurry, 1000 g of methyl cellosolve was added.
The gel fraction is shown in Table 1. Further, the polyfunctional dihydrobenzoxazine 3 was cured in the same manner as in Example 1. The properties of the cured product are shown in Table 1, and the IR spectrum of the cured product is shown in FIG.

Comparative Example 1 Polyfunctional dihydrobenzoxazine 4 was synthesized in the same manner as in Example 1, except that the aniline / p-phenylenediamine mixture was replaced by 931 g (corresponding to 10 mol) of aniline.
A cured product was prepared in the same manner. The gel fraction and cured product properties are shown in Table 1.

Comparative Example 2 In the same manner as in Example 1, except that the compounding amount of aniline / p-phenylenediamine was changed to 279 g of aniline (corresponding to 3 mol) and 378 g of p-phenylenediamine (corresponding to 3.5 mol), polyfunctional dihydrobenzo was similarly used. Oxazine 5 and its cured product were obtained. However, in order to reduce the viscosity of the aniline / p-phenylenediamine mixed slurry, methyl cellosolve 10
00 g was added. The gel fraction and cured product properties are shown in Table 1.

[0028]

[Table 1]

[0029]

The thermosetting resin comprising the polyfunctional dihydrobenzoxazine of the present invention is a dihydrobenzoxazine compound having a relatively high property while having a low crosslink density, and has a high crosslink density while clearing the problems in production. It is a thermosetting resin that can be put to practical use and has achieved top class heat resistance and mechanical properties. Therefore, among thermosetting resins, electronic components that require particularly reliability,
It is suitable for automobile parts, information and communication equipment, structural members, etc.

[Brief description of drawings]

FIG. 1 is the IR of a thermosetting resin cured product obtained in Example 1.
Spectrum.

FIG. 2 IR of cured thermosetting resin obtained in Example 2
Spectrum.

FIG. 3 IR of cured thermosetting resin obtained in Example 3
Spectrum.

Claims (5)

[Claims] 1. A polyphenol compound, a formaldehyde, at least one divalent primary amine compound, and at least one monovalent primary amine compound are added to four components, the number of moles of the phenol nucleus of the polyphenol compound: the number of moles of formaldehyde: Amino group of divalent primary amine compound and 1
The total number of moles of amino groups of the valent primary amine compound is 1 to
In the molar ratio of 3: 2 to 2.2: 1, the number of moles of the amino group of the divalent primary amine compound: the molar ratio of the number of moles of the amino group of the monovalent primary amine compound is 1: 9 to 5: 5. A method for producing a thermosetting resin, which comprises reacting with. 2. The production of a thermosetting resin according to claim 1, wherein the polyphenol compound is a phenol novolac resin obtained by reacting bisphenol or formaldehyde with phenol at a molar ratio of formaldehyde: phenol = 4 to 7:10. Law. 3. A mixture of a polyphenol compound, a divalent primary amine compound and a monovalent primary amine compound is added to an aqueous formaldehyde solution as it is or after being dissolved in a solvent, and the mixture is added at a temperature of 70 to 140 ° C. for 20 minutes to 8 minutes. The method for producing a thermosetting resin according to claim 1, wherein the thermosetting resin is reacted for a time. 4. A thermosetting resin obtained by the manufacturing method according to claim 1. 5. The thermosetting resin according to claim 4,
A cured product obtained by heating at 220 ° C for 20 minutes to 2 hours.