JP2009242525A - Resin composition for rubber compounding and rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phenol resin composition improved in compatibility to rubber, particularly to nonpolar rubber, and to provide a rubber composition improved in reinforcement effect by using the phenol resin composition for precision molding application for electric/electronic components and the like and use for a tire and the like. <P>SOLUTION: The resin composition for rubber compounding contains an etherified phenol resin. Preferably, in the etherified phenol resin, hydrogen of a phenolic hydroxy group is substituted by an alkyl group, a phenyl group, and/or an allyl group, and an etherification rate of the hydroxy group is 20-80%. The resin composition for rubber compounding further contains hexamethylene tetramine or hexamethoxy-methylated melamine resin as a curing accelerator. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a rubber compounding resin composition and a rubber composition.

Conventionally, in order to improve the reinforcing properties such as hardness and modulus of natural rubber and synthetic rubber, there is a method of blending a large amount of compounding agents such as sulfur, vulcanization accelerator, carbon black, etc. It is practiced to use a thermosetting resin, especially a phenolic resin (for example, see Patent Document 1).

Since the phenol resin is a resin containing a large number of hydroxyl groups, it is poorly compatible with so-called nonpolar rubbers such as natural rubber, SBR (styrene butadiene rubber), and BR (butadiene rubber), so that a sufficient reinforcing effect can be obtained. There was a tendency not to be able to.

Japanese Patent Laid-Open No. 01-149847

An object of the present invention is to provide a phenol resin composition that solves the above-mentioned problems of the prior art and has improved compatibility with rubber, particularly non-polar rubber, and the reinforcing effect is improved by the composition. An object of the present invention is to provide a rubber composition that can be used for precision molding applications such as electrical and electronic parts and tires.

Such an object is achieved by the following present inventions (1) to (6).
(1) A rubber compounding resin composition comprising an etherified phenol resin.
(2) The resin composition for rubber compounding according to (1), wherein the etherified phenol resin is an etherified phenol resin in which hydrogen of a phenolic hydroxyl group is substituted with an alkyl group, a phenyl group, and / or an allyl group.
(3) The resin composition for rubber blending according to (2), wherein the etherification rate of the hydroxyl group is 20 to 80%.
(4) The resin composition for rubber blending according to any one of (1) to (3), wherein the resin composition for rubber blending further contains a curing accelerator.
(5) The resin composition for rubber blending according to (4), wherein the curing accelerator is hexamethylenetetramine or hexamethoxymethylated melamine resin.
(6) A rubber composition obtained by blending the resin composition for blending rubber according to any one of (1) to (5).

By using the resin composition for compounding rubber according to the present invention, compatibility with rubber, particularly non-polar rubber, is improved, and therefore a reinforcing effect as good rubber physical properties can be obtained.

The resin composition for compounding rubber according to the present invention is characterized by containing an etherified phenol resin, that is, a resin obtained by etherifying the hydroxyl portion of the phenol resin.

The phenolic resin used in the present invention is not particularly limited, such as a novolak type phenolic resin and a resole type phenolic resin, and is modified with various phenols other than phenol, such as cresol, alkylphenol, resorcinol, etc. in addition to unmodified phenolic resin. Or modified with cashew oil, tall oil, linseed oil, various animal and vegetable oils, unsaturated fatty acid, rosin, alkylbenzene resin, aniline, melamine, rubber, etc., or phenol modified with two or more of these Resin etc. are included.

The hydroxyl group of phenolic resin has a strong polarity, so it has poor compatibility with rubber, especially rubber with relatively non-polar properties such as natural rubber and styrene-butadiene rubber. As a result, the reinforcing effect by the phenol resin is not sufficiently exhibited.
On the other hand, it is considered that the use of a resin having a hydroxyl group etherified reduces the polarity of the phenol resin and improves the compatibility with rubber. Therefore, the dispersibility of the phenol resin in the rubber is also increased, so that the reinforcing effect is enhanced and the properties such as modulus and hardness are considered to be improved.

There are various methods for etherifying the hydroxyl group of this resin, and it is not limited. For example, a resin in which the hydroxyl group of a general phenol resin is etherified to 100% by reacting phenylmethyl ether with formaldehyde in the presence of a strong acid. Can be obtained. As a method for controlling the degree of etherification, a predetermined amount of phenol monomer and ether are reacted in the presence of an acid catalyst to control the degree of etherification, or a 100% etherified resin and a normal novolak resin are mixed. It is possible to control by using.
Various etherified functional groups can be used, and various functional groups such as an alkyl group such as a methyl group, an allyl group, and a phenyl group can be used.

The ratio of etherification with respect to the hydroxyl group of the novolak type phenol resin is not particularly defined, but is usually in the range of 20 to 80% of the total hydroxyl group amount, and more preferably in the range of 30 to 70%.
Here, if it is less than the lower limit, the effect is not sufficient, and if the upper limit is exceeded, curing of the phenol resin does not proceed sufficiently, so that molding becomes difficult and sufficient characteristics as a reinforcing effect cannot be obtained. .

In order to sufficiently cure the etherified phenol resin, it is preferable to use a curing accelerator. As the curing accelerator, hexamethylenetetramine, hexamethoxymethylated melamine resin, tertiary amine, imidazoles, organic phosphine compounds and the like are used. Examples of the method of blending the curing accelerator into the rubber include a method of melt-kneading with a phenol resin in advance and a method of blending with a vulcanizing agent such as sulfur, but are not particularly limited.

The method for obtaining the resin composition for blending rubber according to the present invention has no problem even if, for example, an etherified phenol resin is used in combination with other resins by the following methods.
As a method to be used in combination, there are a melt mixing method in which uniform mixing is performed with a kneader or a roll, a dry mixing method such as pulverization mixing, or a method of blending and kneading both during rubber kneading without performing premixing, etc. It is not limited.
The method of obtaining the rubber composition by blending the rubber compounding resin composition of the present invention with rubber is, for example, kneading various rubbers, carbon black, resin, etc. in advance at around 150 ° C. with a Banbury mixer etc. There is a method of kneading at about 100 ° C. to add sulfur and a curing accelerator, or a method of kneading the above mixture at about 100 ° C. with a roll or the like, but it is not particularly limited.

Hereinafter, the present invention will be specifically described based on examples. However, the present invention is not limited to the examples. Further, “parts” and “%” described in the text all indicate “parts by weight” and “% by weight”.
The resin used is described below.
Novolac type phenolic resin: Sumitomo Bakelite Co., Ltd. PR-50731
Etherified phenolic resin: Durez 75108 manufactured by Durez Corporation

Example 1
40 parts of a novolac-type phenol resin and 60 parts of an etherified phenol resin were mixed and pulverized to obtain a resin composition A for blending powdered rubber according to the present invention.

Example 2
60 parts of a novolak-type phenol resin and 40 parts of an etherified phenol resin were mixed and ground to obtain a resin composition B for blending a powdery rubber according to the present invention.

Example 3
80 parts of a novolak-type phenol resin and 40 parts of an etherified phenol resin were mixed and pulverized to obtain a resin composition C for blending powdered rubber according to the present invention.

Comparative Example 1
A novolac type phenolic resin PR-50731 was used alone.

The formulation is shown in the upper column of Table 1 for the above Examples and Comparative Examples.

<Rubber compounding test>
Various rubber compositions obtained by kneading the compounding composition (parts by weight) shown in Table 2 with a heating roll at 100 ° C. were vulcanized at 180 ° C. for 5 minutes with a hydraulic press to prepare a vulcanized rubber sheet having a thickness of 2 mm. Using this rubber sheet, hardness (Shore A) and 25% tensile modulus were measured according to JIS K 6301, and elastic modulus was measured according to JIS K 6394. The hardness was measured with a durometer manufactured by Toyo Seiki Co., Ltd. The tensile modulus was measured using an autograph manufactured by Shimadzu Corporation at a tensile speed of 50 mm / min. The elastic modulus was measured using a DMS6100 manufactured by Seiko Instruments Inc., and the measurement conditions were tensile mode, 60 ° C., and frequency 10 Hz.
These results are shown in the lower column of Table 1.

As is apparent from Table 1, it was confirmed that when an etherified resin was used, the modulus and hardness at a high temperature range were improved as compared with Comparative Example 1 in the case of using a commonly used phenol resin. .

The resin composition for compounding rubber according to the present invention is characterized by containing a phenol resin obtained by etherifying a hydroxyl group, and the reinforcing effect is improved because compatibility with rubber, particularly nonpolar rubber is improved. To do. Therefore, according to the present invention, higher functionality can be realized in precision molding applications such as electric and electronic parts used in automobiles and the like and tire applications.

Claims (6)

A resin composition for compounding rubber, comprising an etherified phenol resin. 2. The resin composition for rubber compounding according to claim 1, wherein the etherified phenol resin is an etherified phenol resin in which hydrogen of a phenolic hydroxyl group is substituted with an alkyl group, a phenyl group, and / or an allyl group. The resin composition for rubber blending according to claim 2, wherein the etherification rate of the hydroxyl group is 20 to 80%. The resin composition for rubber blending according to any one of claims 1 to 3, wherein the rubber blending resin composition further contains a curing accelerator. The resin composition for rubber compounding according to claim 4, wherein the curing accelerator is hexamethylenetetramine or hexamethoxymethylated melamine resin. The rubber composition formed by mix | blending the resin composition for rubber | gum mixing of any one of Claims 1-5.