JPH03741A - Improvement of adhesion between steel cord and rubber - Google Patents

Abstract

PURPOSE:To improve adhesion between a steel cord and a rubber regardless of the kind of a plating on the surface of the steel cord by performing a surface treatment of a plated steel cord with triazine, pressing it against a specified rubber compsn. and vulcanizing them. CONSTITUTION:After the surface treatment of a plated steel cord with triazine or a triazine deriv., the cord is pressed against a rubber compsn. comprising 0.5-3 pts.wt. resorcinol or a precondensate of resorcinol-formaldehyde, 1-6 pts.wt. hexamethoxymethymelamine and 6 pts.wt. or less sulfur and vulcanized. As the triazine or the triazine deriv., compd. of formulas I and II are cited. In the formulas I and II, R is -OR' or -SR' (wherein R' is H, an allyl group, an alkyl group, an alkenyl group, a phenyl group, a phenylalkyl group, etc.); R1 and R2 are each the same as R'; M is H, Na, K, Li, NH4, 1/2 Mg, 1/2 Ca, 1/2 Zn, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for improving the adhesion between a steel cord whose surface is plated and rubber.

[Conventional technology]

Conventionally, various methods are known for bonding steel cord and rubber. Among these, an adhesion method with excellent water resistance is, for example, a method in which a plated steel cord is surface-treated with triazine or a triazine derivative, and then this treated cord is adhered to diene rubber (Japanese Patent Laid-Open No. 54 -33576), a method of adhering the surface-treated steel cord to ethylene propylene rubber (EP rubber) (Japanese Patent Laid-Open No. 56-86414),
Publication No.) etc. The reason why these steel cords surface-treated with triazine or triazine derivatives has excellent water-resistant adhesion to rubber is that triazine or triazine derivatives react with the parts of the steel cord surface that are easily corroded by moisture, and the corrosion starts at the point where the corrosion starts. It is believed that this is because the triazine or triazine derivative that has reacted with the rubber is combined with the rubber.

However, the adhesion between the steel cord treated with triazine or triazine derivatives and rubber differs depending on the type of plating applied to the surface of the steel cord.
Although a relatively good improvement in adhesion was observed in the case of nickel plating and iron plating, it was found that in the case of brass plating, the adhesion decreased.

[Problem to be solved by the invention]

An object of the present invention is to provide a steel cord with good adhesion to rubber, which does not depend on the type of coating on the surface of the steel cord, and in particular, which has good adhesion to brass-plated steel cord, which is said to have poor adhesion. The purpose of the present invention is to provide an adhesion method that can be used to adhere the material.

[Means to solve the problem]

In the present invention, after surface-treating a plated steel cord with triazine or a triazine derivative, 0.5 to 3 parts by weight of resorcin or an initial condensate of resorcin-formaldehyde, 1 to It is characterized by being vulcanized by pressure bonding with a rubber composition containing 6 parts by weight of hexamethoxymethylmelamine and 6 parts by weight or less of sulfur.

As the triazine or triazine derivative used in the present invention, compounds represented by the following formula (a) or (b) can be exemplified.

In the above formula, R is -OR' or -SR''(R' is hydrogen, allyl group, alkyl group, alkenyl group, phenyl group, phenylalkyl group, alkylphenyl group or cycloalkyl group), M is hydrogen , Na, to, Lt, N
Ha, 1/2Mg, 1/2Ca, 1/2Ba or 1/2
2Zn.

In the above formula, R + and Rz are hydrogen, allyl group, alkyl group, alkenyl group, phenyl group, phenylalkyl group, alkylphenyl group or cycloalkyl group, M is hydrogen,
Na, + Li, NH4゜1/2Mg, 1/2C
a, 1/2Ba or 1/2Zn.

Examples of the compound represented by formula (a) include 2
, 4.6 trithiol-S-triazine, phenyl-4
,6 dithiol-S-triazine, 2methoxy-4,6
Examples include dithiol-S-triazine, 2ethoxy-4,6dithiol-S-)lyazine, and 2phenoxy-4,6dithiol-S-)lyazine.

Examples of compounds represented by formula (b) include 6
diallylamino-1.3.5-) riazine-2,4-dithiol, 2-dibutylamino-4,6-dithiol-S-)
riazine, 2-dilaurylamino-4,6-dithiol-calcium, 2-ethylphenylamino-4,6-dithiol-S-) riazine dilithium, 2-(γ-carboxylpropylamino)-4,6-dithiol-S-) lyazine calcium, 2-octylamino-4-butylamino-6
-thiol-3-triazine copper, 2anilino-4,6-
Dithiol-S-triazine, 2,4-dianilino-6
Examples include thiol-s-triazine, 2,4-bisdimethylamino-6thiol-S-)riazine, and 2-(P-dimethylamino)-4methoxy-6thiol-S-)riazine.

The method of treating the plated steel cord with these triazine or triazine derivatives is not particularly limited, and various known methods can be applied. For example, the treatment can be carried out by dissolving triazine or a triazine derivative in various solvents such as acetone or ethylene glycol, and dipping or spraying the steel cord in the solution.

On the other hand, a rubber composition that is vulcanized by being pressure-bonded to a steel cord treated with triazine or a triazine derivative contains 0.5 to 3 parts by weight of an initial condensate of resorcin or resorcin to 100 parts by weight of the rubber component. A rubber composition containing an initial condensate with formaldehyde, 1 to 6 parts by weight of hexamethoxymethylmelamine, and up to 6 parts by weight of sulfur is used. If resorcinol or an initial condensate of resorcinol and formaldehyde is not mixed with hexamethoxymethylmelamine in an amount ranging from 0.5 to 3 parts by weight and from 1 to 6 parts by weight, the surface-plated steel cord will Good adhesion cannot be obtained, and similarly, if the amount of sulfur exceeds 5 parts by weight, good adhesion between the steel cord and rubber cannot be obtained. The amounts of hexamethoxymethylmelamine and sulfur are particularly important for improving adhesion to brass-plated steel cords, which are said to have poor adhesion.

Here, the rubber components include natural rubber, styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), polybutadiene rubber,
Examples include polychloroprene rubber, polyisoprene rubber, isoprene/isobutylene copolymer rubber, and the like.

The surface of the steel cord to be treated by the method of the present invention is plated with various metals such as brass, nickel, iron, etc., but it can exhibit good adhesion no matter which metal it is plated with. . In particular, it can exhibit extremely excellent adhesion to brass-plated steel cords, which were said to have poor adhesion using conventional techniques.

EXAMPLES Hereinafter, the effects of the present invention will be specifically explained with reference to Examples.

In addition, adhesiveness was evaluated by the following test method.

JLa1 group friend: Using a 5-piece brass-plated steel cord with a wire diameter of 0.25 mm, the rubber and wire were crimped in advance with an embedded length of 12.5 mm in accordance with ASTM D-2229. After being left to absorb moisture for 14 days at 30°C and a humidity of 86χ, it was vulcanized at 160°C for 15 minutes and bonded, followed by a pull-out test to measure the pull-out force and rubber coverage.

The rubber coverage was determined to be 100χ when the entire surface of the wire after drawing was covered with rubber, and 0χ when it was not covered with rubber at all.

EXAMPLES, COMPARATIVE EXAMPLES, CONVENTIONAL EXAMPLES Four types of rubber compositions having different compositions shown in Table 1 were prepared. The numerical values in the table are shown in parts by weight.

In Table 1, rubber composition (c) is a composition that satisfies the rubber composition specified in the present invention, and (a) and (b) are respectively
Conventional rubber compositions with low and high sulfur contents; (d) is a comparative rubber composition with only a higher sulfur content than specified in the present invention;

Brass-plated steel cords were surface-treated under the four treatment conditions A, B, C, and D shown in Table 2, and the above-mentioned rubber compositions (a) and (b) were applied to these steel cords, respectively.
, (c) and (d) were coated and vulcanized, and then an adhesion test was conducted.

Table 3 shows the measurement results of the pull-out force, and Table 4 shows the measurement results of the rubber coverage.

Table 1 Note: 1) Penacolite Resin B-18S (Coppe
RS Company) 3) Silenz 963 Resin (American Shanamid Company) Table 2 Table 3 (The unit in the table is Kg.) Table 4 (The unit in the table is %.) From Tables 3 and 4, the book (c)- corresponding to an embodiment of the invention
The combinations of the rubber compositions A, (c)-B and (c)-C and the surface treatment of the steel cord all have larger pull-out force and rubber coverage ratio than other combinations ( , it can be seen that the adhesion between the rubber and the cord is excellent.In other words, when brass-plated steel cord is surface-treated with triazine or triazine derivatives, the adhesion has conventionally decreased. Improvements have been made possible by the present invention.

Although the above embodiment is a case of a steel cord plated with brass, good adhesion can also be obtained with a steel cord plated with other plating such as nickel plating or iron plating.

〔Effect of the invention〕

According to the present invention, a plated steel cord is surface-treated in advance with triazine or a triazine derivative, and the rubber to be bonded is a rubber containing specific amounts of resorcinol or an initial condensate of resorcinol-formaldehyde, hexamethoxymethylmelamine, and sulfur. The use of the composition allows good adhesion with rubber, regardless of the type of plating of the steel cord.

In particular, extremely excellent rubber adhesion can be obtained even to brass-plated steel cords, which were conventionally thought to have poor adhesion.

Claims (1)

[Claims] After surface treating the plated steel cord with triazine or a triazine derivative, 0.5 to 3 parts by weight of resorcin or an initial condensate of resorcin-formaldehyde, and 1 to 6 parts by weight of hexamethoxymethyl per 100 parts by weight of raw rubber. A method for improving the adhesion between a steel cord and rubber, which comprises press-bonding and vulcanizing a rubber composition containing melamine and 6 parts by weight or less of sulfur.