JPS6021176B2 - Rubber composition for covering metal cords - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rubber composition for covering metal cords, and more particularly to a rubber composition for covering metal cords that has good adhesion between materials in the production of composites of rubber and metal materials. It is about things.

Conventionally, composite materials that combine metal materials with high strength and rigidity and elastic and flexible rubber have been used in many industrial products, and the adhesive strength between the metal and rubber that make up these materials is The impact on product performance is significant.

Conventionally, when sulfurizing a metal material such as a steel cord and a rubber composition, a method of adding organic acid cobalt salts to the rubber composition, a method of adding HRH (hexamethylenetetramine,
Methods based on resorcinol, silica, etc. are known.

However, these methods have the disadvantage that the adhesive strength decreases significantly when the adhesive undergoes a history such as overvulcanization or heat aging. As a result of research on improving the adhesion between metal and rubber, the present inventors found that
By adding 0.5 to 20 parts by weight of "metal salt of phenolic resin having a carboxyl group" to 10 parts by weight of raw rubber, adhesion to metal materials, especially after heat aging, is significantly improved. This led to the completion of the present invention.

A phenol resin having a carboxyl group is a phenol resin in which a structural unit represented by the following general formula {a' is polymerized alone (n=0 or 1), or a structural unit represented by the general formula 'a'. This is a phenol resin obtained by copolymerizing the structural unit represented by the following general formula 'b-.

(X: alkyl group (1 to 5 carbon atoms) or hydroxyl group m=0
~2) The average molecular weight of the resin is preferably about 300 to 2000.

Phenolic resins having such carboxyl groups are
Specifically, it is obtained by a condensation reaction between phenol carboxylic acid and formaldehyde, or by a co-condensation reaction between phenol carboxylic acid, phenols, and formaldehyde.

Examples of the phenolic carboxylic acids include salicylic acid, metaoxybenzoic acid, paraoxybenzoic acid, Q-resorcylic acid and 8-resorcylic acid, and among these, paraoxybenzoic acid is the most effective. Phenols include, for example, carbolic acid, cresol, tert. - Examples include butylphenol and resorcinol. For the formaldehyde used in the condensation, a substance capable of generating formaldehyde, such as formalin, paraform, methylal, hexa, etc., is used. It is essential that the resin used in the present invention has both a 10H group of phenol and a -COO group of carboxyl, and the hydrogen of the carboxyl group is used by replacing it with a metal atom. Therefore Fe/-
The molar ratio of carponic acid and phenols is 1:0 to 1:2.
It is preferable that the condensation or co-condensation is carried out in the range of 0. If the phenol is co-condensed with the phenol carboxylic acid in excess of 2 tones, the content of carboxyl groups in the resin will be relatively reduced. Even when used as a salt, the effect of improving adhesion is weak and disadvantageous. An example of the synthesis method for "phenol resin having a carboxyl group" is from "Kobunshi Kagaku" Vol. 9, page 404 (1952), and 1.
Condensation is carried out using an acid or alkali catalyst as described from page 7 (1953). An example of synthesizing a ``metal salt of a phenol resin having a carboxyl group'' by using a ``phenol resin having a carboxyl group'' as a metal salt is to react the phenol resin having a carboxyl group with sodium carbonate to create a hydrogen oxide in the carboxyl group. replaces a sodium atom, yielding a sodium salt.

When producing other metal salts, for example, zinc salts can be obtained by reacting sodium salts with zinc chloride. here,"
It is not necessary to convert all the carboxyl groups contained in the phenolic resin containing carboxyl groups into metal salts, but considering the reaction yield and kneadability with rubber, it is possible to change only some of the carboxyl groups into metal salts. It's okay.

The metal salts used in the present invention include anhydrous salts or water salts of sodium, potassium, magnesium, calcium, aluminum, iron, nickel, tin, cobalt, zinc, copper, etc. Among these, iron salts and nickel salts , cobalt salts are particularly effective.

In order to obtain the effects of the present invention, 0.5 to 20 parts by weight, preferably 1.5 to 6 parts by weight of "metal salt of phenolic resin containing a carboxyl group" is added to 100 parts by weight of raw rubber. If the amount is less than 0.5 parts by weight, the effect on adhesive properties will be weak, and if it exceeds 2 parts by weight, the physical properties of the rubber will be adversely affected.

The raw rubber, compounding agents, and metal materials used in the present invention are not particularly limited. Natural rubber, synthetic rubber, and mixtures thereof can be used as the raw rubber, and zinc white, vulcanization accelerator,
Commonly used rubber compounding materials such as anti-aging agents, carbon black, and silica are blended according to their intended use. It is preferable that the adhesive surface of the metal material is treated by an appropriate method such as copper alloy plating or zinc plating. It is also possible to use the method according to the present invention in combination with conventional methods such as organic acid cobalt salts and HRH.

The purpose of the present invention is to provide a rubber composition that has good adhesion to metal materials, and is used for composites of metal and rubber, particularly for wheel tire breakers, carcass parts, compare belts, etc. be done. Examples are given below,
This invention will be specifically explained.

Examples, Comparative Examples, Standard Examples Preparation of Rubber Composition Masterbatch in which raw rubber and compounding agents other than N-oxydiethylene-2-penzothiazole sulfenamide, hexamethylenetetramine, and sulfur were mixed in a Banbury mixer. Then, the remaining compounding ingredients were added in an open roll to make a rubber composition.

Adhesion Test A rubber composition was coated on both sides of steel cords arranged in parallel with 12.5 side spacing, and vulcanization adhesion was performed at 15,000°C for 30 minutes.

The pullout test was conducted in accordance with ASTM-D2229,
Adhesiveness (before heat aging) was evaluated by pulling it out. At the same time, the samples prepared above were heat aged in a gear oven at 100°C for 7 hours, and then a pull-out test was conducted to evaluate the adhesion after heat aging. Fe/containing carboxyl group
Synthesis of metal salt of metal resin In a flask, put 100% of paraoxybenzoic acid, 25% of paraform, 10% of concentrated hydrochloric acid, and 400% of dioxane as a solvent. After heating at reflux temperature for 2 hours under lighting, the solvent was heated at reflux temperature for 2 hours. was removed under reduced pressure, washed several times with water, and dried to obtain a resinous "condensate A."

The molecular weight was approximately 800. ``Condensate A'' was reacted with an aqueous potassium carbonate solution and dried to obtain ``K salt of Condensate A''.

The end point of the reaction was determined by pH. Ferric chloride was added to an aqueous solution of "K salt of condensate A", and the resulting precipitate was washed with water and dried to obtain "Fe salt of condensate A".

Cobalt chloride was added to an aqueous solution of "K salt of condensate A", and the resulting precipitate was washed with water and dried to obtain "Co salt of condensate A".

Nickel chloride was added to an aqueous solution of "K salt of condensate A", and the resulting precipitate was washed with water and dried to obtain "Ni salt of condensate A".

In a flask, 138 g of paraoxybenzoic acid, para
t. - Add 150 g of butylphenol, 6 g of paraform, 4 g of concentrated hydrochloric acid and 100 g of dioxane as a solvent,
After heating at reflux temperature for 6 hours with condensation, the solvent was removed under reduced pressure, washed several times with water, and dried to obtain a resinous "condensate B".

"Condensate BNa salt" was obtained by reacting "Condensate B" with sodium carbonate and drying.

By reacting ``Na salt of condensate B'' with magnesium chloride, cupric chloride, and zinc chloride in an aqueous system and washing with water and drying, ``Mg salt of condensate B'', ``Cu salt of condensate B'', and ``condensate B'' were combined. Obtained Item B, ZN Hatake. Table 1 shows the results using Examples 1 to 1 Stop Proportions 1 to 3 and Standard Example 1 Steel Co., Ltd. (36) structure.

Standard Example 1 is an ordinary rubber compound, Comparative Examples 2 and 3 are typical organic acid cobalt compound examples, and Comparative Example 1 is a typical HRH compound example. This clearly shows that Examples 1 to 1 of the present invention
It can be seen that the blend of No. 0 has a high adhesive strength after aging when compared with Standard Example 1, and also when compared with Comparative Examples 1 to 3, and has improved adhesiveness. It also has improved adhesion before aging. Examples 11-1 & Standard Example 2 Table 2 shows the results using steel cords with a 7x41 structure.

Although the level of retention rate differs from that in Table 1 due to the difference in the structure of the wire and the content of the rubber compounding, the adhesion of Examples 11 to 18 is clearly improved compared to Standard Example 2. Ship Ship Se J V Blood Treatment S 1 Hair ■ ・ Vertical phosphorus baby, `` Ri○ −.

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As explained above, the rubber composition for coating metal cords of the present invention can be used in combination with metal materials. Because it has excellent adhesive properties, especially after heat aging, it is used for composites of metal materials and rubber compositions, such as breaker carcass materials for car tires and core bodies for compare belts. There are advantages to using it.

Claims (1)

[Scope of Claims] 1. A rubber composition for coating a metal cord, characterized in that 0.5 to 20 parts by weight of a metal salt of a phenol resin having a carboxyl group is added to 100 parts by weight of rubber. 2 The phenolic resin having a carboxyl group is a phenolic resin consisting only of polymerized units represented by the following general formula (a) ▲ Numerical formula, chemical formula, table, etc. ▼ (In the above formula, n is 0 or 1) or the general formula (
The polymerized unit of a) and the following general formula (b) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the above formula, )
The rubber composition for coating a metal cord according to claim 1, which is a phenolic resin comprising a copolymerized unit represented by: