JPH083421A - Phenolic resin composition - Google Patents

Abstract

PURPOSE:To obtain a phenolic resin composition that is excellent in fast curability and shows strength equal to that of a conventional phenolic resin composition free of any dicarboxylic acid. CONSTITUTION:This phenolic resin composition comprises 100 pts.wt. novolak phenolic resin, 3 to 20 pts.wt. hexamethylenetetramine as a curing agent, and 0.1 to 2.0 pts.wt. at least one curing auxiliary selected from dicarboxylic compounds.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a molding material, a friction material,
The present invention relates to a phenol resin composition for a binder for grindstones, castings, and other inorganic and organic substances, and more particularly to a phenol resin composition for a binder having both fast curing property and high strength.

[0002]

2. Description of the Related Art Generally, a phenol resin composition mainly composed of high ortho novolac is used as a fast-curing phenol resin composition, or an aromatic acid such as salicylic acid or benzoic acid is used as a curing aid. Are known. However, the phenol resin composition using the high ortho novolac has a drawback that it is excellent in rapid curing property, but inferior in heat resistance as a characteristic of a molded product. Also,
Phenolic resin compositions that use aromatic acids as a curing aid have a heat resistance and strength of the molded product due to the fact that during curing, hexamine decomposes rapidly, leaving voids or leaving aromatic acids. However, there is a drawback that the characteristics such as

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention makes use of the characteristics of a fast-curing phenol resin composition, and as a result of earnest studies to improve various properties such as strength and heat resistance of a molded product, a curing aid is obtained. By using dicarboxylic acids as the above, it was found that rapid curing and the strength, heat resistance, etc. of molded products can be improved, and based on this finding, various studies have been advanced to complete the present invention. Is.

[0004]

The present invention is based on 100 parts by weight of a novolac type phenolic resin, 3 to 20 parts by weight of hexamethylenetetramine as a curing agent, and at least one curing aid selected from dicarboxylic acid compounds. 0.
The present invention relates to a phenol resin composition for a binder containing 1 to 2.0 parts by weight.

In the present invention, the amount of the dicarboxylic acid compound used as the curing aid in the present invention is 0.1 to 2.0 parts by weight, preferably 0.3 parts by weight, based on the novolac type phenol resin. ~ 2.0 parts by weight. When the amount is 0.1 parts by weight or less of the novolac type phenol resin, the effect of rapid curing is not sufficient, and when it is 2.0 parts by weight or more, the curing rate becomes very fast, but the influence of acid increases and the strength and heat resistance are increased. The characteristics of the molded product, such as the properties, deteriorate.

The dicarboxylic acid compound used as a curing aid in the present invention is an aliphatic dicarboxylic acid compound having a pKa1 (dissociation constant) of 2.5 to 4.0 at 25 ° C., and malonic acid, fumaric acid, Examples include malic acid, aspartic acid, methylmalonic acid, ethylmalonic acid, and ethylmethylmalonic acid. When the pKa1 (dissociation constant) at 25 ° C. is 2.5 or less, there is a problem of molding failure due to foaming and curing speed being too fast at the time of curing due to too strong acid strength.
Above, the strength of the acid is too weak and the effect of quick curing is low. The dicarboxylic acid compound is decomposed or sublimated during curing,
It is preferable that it is less likely to remain in the molded article, and even if it remains, it is desirable that it has a small molecular weight and does not significantly affect the phenol resin skeleton. From this, the dicarboxylic acid compound is an aliphatic dicarboxylic acid compound, and preferably has a small molecular weight. As a method for mixing the dicarboxylic acid compound, which is the curing aid used in the present invention, with the phenol resin,
Any of the initial, middle, and late stages of the manufacturing process, melt mixing, and pulverization mixing may be used.

The novolak type phenolic resin used in the present invention is a novolak type phenolic resin obtained by using phenols and aldehydes as a catalyst from an acid. Phenols used here are phenol, orthocresol, metacresol, paracresol, xylenol, paratertiarybutylphenol, paraoctylphenol, paranonylphenol, paraphenylphenol, bisphenol A and other phenols and mixtures thereof. is there.

The aldehydes include formaldehyde, acetaldehyde, butyraldehyde, acrolein, and mixtures thereof, and it is also possible to use a substance which is a source of generation of these aldehydes or a solution of these aldehydes. As the acid catalyst, oxalic acid, paratoluenesulfonic acid, xylenesulfonic acid, phenol
Organic acids such as sulfonic acid and inorganic acids such as hydrochloric acid and sulfuric acid can be used.

The amount of hexamethylenetetramine compounded is 3 to 20 relative to the novolac type phenol resin.
Parts by weight, preferably 8 to 16 parts by weight. When it is 3 parts by weight or less with respect to the novolac type phenol resin, the crosslink density is low and heat resistance is insufficient, and when it is 20 parts by weight or more, it is contained in the composition in which the decomposition gas of hexamethylenetetramine is cured. They are trapped and create many voids, which reduces the strength of the cured product.

The phenol resin composition of the present invention comprises, as a filler, clay, cryolite, calcium carbonate, silicon dioxide, inorganic filler such as glass fiber, pulp, organic fiber,
Organic fillers such as rice husks and cured products, and additives such as surfactants, foaming agents and coupling agents can be contained.

[0011]

EXAMPLES The present invention will be described in detail below with reference to examples.
All "parts" and "%" described herein indicate "parts by weight" and "% by weight". Example 1 A four-necked flask was charged with 1042 parts of phenol, 677 parts of 37% formaldehyde, and then 10 parts of oxalic acid, and the temperature was gradually raised to 1 after the temperature reached 96 ° C.
After refluxing for 20 minutes, dehydration reaction was carried out under vacuum. After completion of the reaction, 1 part of malonic acid was added at 150 ° C., stirring and mixing were carried out for 30 minutes, and the kettle was discharged. Number average molecular weight M solid at room temperature
Thus, 1001 parts of a dicarboxylic acid compound-added novolac type phenol resin having n = 800 was obtained. 1000 parts of the obtained dicarboxylic acid compound-added novolak-type phenol resin and 150 parts of hexamethylenetetramine were mixed and pulverized to obtain a phenol resin composition A.

Example 2 The reaction was carried out in the same manner as in Example 1, and 10 parts of malonic acid was added at 130 ° C. after the reaction was completed.
The mixture was stirred and mixed for 1 minute, and then discharged from the kettle. Mn = solid at room temperature
Thus, 1010 parts of a dicarboxylic acid compound-added novolak type phenol resin of 800 was obtained. 1000 parts of the obtained dicarboxylic acid compound-added novolak-type phenol resin and 150 parts of hexamethylenetetramine were mixed and pulverized to obtain a phenol resin composition B.

Example 3 The same reaction as in Example 1 was carried out. After the reaction was completed, 20 parts of malonic acid was added at 130 ° C.
The mixture was stirred and mixed for 1 minute, and then discharged from the kettle. Mn = solid at room temperature
Thus, 1020 parts of a dicarboxylic acid compound-added novolak type phenol resin having a viscosity of 800 was obtained. 1000 parts of the obtained dicarboxylic acid compound-added novolak type phenol resin and 150 parts of hexamethylenetetramine were mixed and pulverized to obtain a phenol resin composition C.

Example 4 The reaction was carried out in the same manner as in Example 1, and after the reaction was completed, 10 parts of fumaric acid was added at 30 ° C.
The mixture was stirred and mixed for 1 minute, and then discharged from the kettle. Mn = solid at room temperature
Thus, 1010 parts of a dicarboxylic acid compound-added novolak type phenol resin of 800 was obtained. 1000 parts of the obtained dicarboxylic acid compound-added novolac type phenol resin and 150 parts of hexamethylenetetramine were mixed and pulverized to obtain a phenol resin composition D.

Comparative Example 1 The reaction was carried out in the same manner as in Example 1, and after completion of the reaction, the kettle was discharged. 1000 parts of phenol resin having a solid Mn = 800 at room temperature was obtained. 1000 parts of the obtained novolac type phenol resin was mixed and pulverized with 150 parts of hexamethylenetetramine to obtain a phenol resin composition E.

(Production Example of Molded Article) The phenol resin compositions obtained in Examples 1 to 4 and Comparative Example 1 were melt-mixed with a kneader in the following composition to obtain a molding material. Phenol resin composition: 1000 parts Glass fiber: 350 parts Clay: 150 parts The above molding material was heat molded at a molding pressure of 280 kg / cm ^{2 at} a molding temperature of 165 ° C. for 5 minutes to obtain a molded product.

Table 1 shows the gelation times of the obtained five kinds of phenol resin compositions and the characteristic values of the obtained molded products. (Table 1) Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Phenolic resin composition A B C D E ─────────────────────── ──────────── Gelation time (150 ℃, seconds) 98 88 84 90 90 112 Flexural strength (MPa) 225 240 238 237 218 Flexural modulus (MPa) 13280 13400 13300 13280 13310 Charpy impact Strength 6.6 6.4 6.5 6.6 6.0 (kJ / m ² )

The test method is as follows. Gelation time: 0.5 g of the sample was mixed with a spatula on a hot plate at 150 ° C., and the time until the string was not pulled was defined as the gelation time. Bending strength: JIS K 7203 Bending elastic modulus: JIS K 7203 Charpy impact strength: JIS K 7111

[0019]

EFFECT OF THE INVENTION The phenolic resin composition for a binder containing a dicarboxylic acid of the present invention has the same strength as that of a conventional phenolic resin composition containing no dicarboxylic acid,
The effect of quick curing is recognized.

Claims (2)

[Claims] 1. Hexamethylenetetramine 3 to 3 as a curing agent per 100 parts by weight of a novolac type phenol resin.
A phenol resin composition for a binder, which contains 20 parts by weight and 0.1 to 2.0 parts by weight of at least one curing aid selected from dicarboxylic acid compounds. 2. The phenol for a binder according to claim 1, wherein the dicarboxylic acid compound as the curing aid is an aliphatic dicarboxylic acid, and the value of pKa1 (dissociation constant) at 25 ° C. is 2.5 to 4.0. Resin composition.