JPS61152717A - Phenolic resin composition modified with boric acid - Google Patents

Abstract

PURPOSE:To produce the titled composition giving a molded article having improved heat-resistance without generating gas during molding, by using a resol-type phenolic resin wherein phenols and aldehydes are bonded with each other in a high-ortho form, and modifying the phenolic resin with boric acid, etc. CONSTITUTION:A phenolic compound is made to react with an aldehyde in the presence of a bivalent metal hydroxide (e.g. magnesium hydroxide) as a catalyst to obtain a resol-type phenolic resin wherein the molar ratio of the aldehyde bonded to phenol is 1.0-2.0, and the ratio of ortho-bond to para-bond is >=1.5. The objective composition can be produced by reacting the phenolic hydroxyl group of the phenolic resin with 0.15-0.5mol of boric acid or 0.075-0.25mol of boron oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a boric acid-modified phenolic resin that is used to produce molded products with excellent heat resistance.

[Prior art]

The method for producing boric acid-modified phenolic resin includes a method in which phenols are reacted with boric acid or boron oxide under dehydration to form phenylborate, and then further reacted with aldehydes (
For example, Japanese Patent Publication No. 45-40071), a method in which phenols are reacted with aldehydes and then boric acid etc. (for example, Japanese Patent Publication No. 40-13073, Japanese Patent Publication No. 47-7-
18867) is generally known. However, since the reactivity of phenols with aldehydes largely depends on the phenolic hydroxyl group, when the diphenolic hydroxyl group is esterified with boric acid or the like, the reactivity with aldehydes is significantly impaired. Also, the aforementioned special public service in 1977-
13073 and Japanese Patent Publication No. 47-18867, when a boric acid ring is reacted after converting phenols into a resin, intermolecular cross-linking occurs because boric acid is trifunctional, resulting in gelation. cause Therefore, it is difficult to react sufficiently, and when making molded products using the obtained resin,
As boric acid esterification progresses during molding, a large amount of gas is generated, which has the disadvantage of causing molding defects such as gas blistering and gas cracking.

[Purpose of the invention]

The present invention was developed as a result of intensive research aimed at obtaining a highly reactive boric acid esterified phenolic resin, which could not be obtained in the past.It was found that it is sufficient to react a high ortho type resol type phenolic resin with boric acid to generate intramolecular cross-linking. They obtained the knowledge that gelation does not occur even when reacted with , and there is little gas generation during molding.Based on these findings, various studies were conducted and the present invention was completed.

[Structure of the invention]

The present invention provides a resol-type phenolic resin in which the molar ratio of aldehydes to phenols is in the range of 1.0-ZO and the ratio of ortho bonds to para bonds is L5 or more. 0.15 to α5 mol of boric acid or 0.075 to the phenolic hydroxyl group of
This is a boric acid-modified phenol resin composition characterized by being modified with ~α25 moles of boron oxide.

In the present invention, the molar ratio of aldehydes to phenols in the resol type phenolic resin is 1.0.
-ZO is preferred; if it is less than 1.0, it loses self-curing properties and becomes thermoplastic. Moreover, if it is more than 2.0, the odor during molding will be strong and the amount of gas generated will be large, making it unsuitable for practical use. The ratio of ortho bonds to para bonds is preferably L5 or higher, and the higher the amount of modification with boric acid or the like, the higher the ratio of ortho bonds is. In order to produce such a high ortho type resol type phenolic resin, a method using a divalent metal hydroxide, such as magnesium hydroxide, zinc hydroxide, etc., or a salt thereof, such as zinc acetate, as a catalyst is generally used. Knowing this, it is possible to determine the ratio of ortho bonds and para bonds at the bottom of the mountain. Furthermore, the amount of modification of boric acids is 0.15 to 0.5 mole of boric acid or 0.075 to 0.0 mole of boric acid based on the phenolic hydroxyl group of the phenol.
．． 25 moles of boron oxide is preferable; below this, no improvement in heat resistance is observed, and above this, unreacted boric acid remains, causing gas generation during molding.

An organic or inorganic additive φ filler may be added to the resol type phenolic resin obtained as described above, if necessary. Further, these components may be mixed simply by pulverization, solution mixing, or melt mixing, and the resin composition can be in a powder, solid, or liquid form.

Phenols as used in the present invention include phenol, alkylphenols such as orthocresol, metacresol, vala-cresol, xylenol, paratertiary-butylphenol, and mixtures thereof. Examples of aldehydes include formaldehyde, acetaldehyde, butyraldehyde, acrolein, and mixtures thereof. Substances that generate these aldehydes or solutions of these aldehydes may also be used.

According to the present invention, salts and oxides such as hydroxides and carbonates of divalent metals such as calcium hydroxide, magnesium hydroxide, and zinc hydroxide can be used as catalysts for the reaction between phenols and aldehydes. Furthermore, other alkali catalysts and acid catalysts can be used in combination.

〔Effect of the invention〕

The resin composition according to the present invention can be used as a raw material for molding materials, for example.
Used in organic fiber binders, rubber compounding agents, abrasive grain binders, inorganic fiber binders, coating materials for electronic and electrical parts, resins for laminates, binders for friction materials, binders for sliding parts, etc. A product with excellent heat resistance can be obtained.

〔Example〕

Hereinafter, the present invention will be explained in detail using examples.

All "parts" and "Ill" herein indicate "parts by weight" and "% by weight."

Example 1 282 parts of phenol, 365 parts of 37% formalin, and 4 parts of magnesium oxide were placed in a flask equipped with a stirrer, a reflux condenser, and a temperature needle, heated while stirring, and after refluxing 1
The reaction was carried out at 00°C for 1 hour.

Thereafter, 55 parts of boric acid was added, and the mixture was allowed to react while being dehydrated under vacuum to obtain 440 parts of a solid resin. The ratio of ortho bonds to para bonds was 2.3 depending on the heel.

Example 2 480 parts of a solid resin was obtained in the same manner as in Example 1 except that 92 parts were changed from 55 parts of boric acid.

Comparative Example 1 410 parts of a solid resin was obtained in the same manner as in Example 1 except that 19 parts were changed from 55 parts of boric acid.

Comparative Example 2 530 parts of a solid resin was obtained in the same manner as in Example 1 except that 365 parts of 37m formalin was changed to 608 parts.

Comparative Example 3 440 parts of a solid resin was obtained in the same manner as in Example 1 except that 4 parts of magnesium oxide L was replaced with 1.4 parts of sodium hydroxide.

Table 1 shows the properties of the solid boric acid-modified phenol resins obtained in the above Examples and Comparative Examples.

As is clear from Table 1, the weight loss of the boric acid-modified phenolic resin produced in the examples was small in both the low temperature and high temperature ranges.
Shows good heat resistance.

Claims (1)

[Claims] The phenol is added to a resol type phenolic resin in which the molar ratio of aldehydes to phenols is in the range of 1.0 to 2.0, and the ratio of ortho bonds to para bonds is 1.5 or more. 0.15 to 0.5 mol of boric acid or 0.075 mol to the phenolic hydroxyl group of
A boric acid-modified phenol resin composition characterized in that it is modified with ~0.25 mol of boron oxide.