JPH1160820A - Accelerator for adhesion between metal and rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve excellent adhesiveness and also improve adhesion properties in vulcanizing at a high temperature and the storage stability of a rubber after compounding, by compounding an organic cobalt compound together with a metallic soap selected from among those based on nickel, zinc and zirconium. SOLUTION: Organic cobalt compounds usable include a cobalt compound which is a salt formed with an organic moiety, such as a metallic soap derived from a fatty acid, a cobalt-boron complex compound, cobalt acetylacetonate or the like. It is preferred that the organic cobalt compound is admixed with a metallic soap in a ratio [(Ni, Zn, Zr)/Co; a weight ratio between metals] of 0.01 to 20. This adhesion accelerator is used through being mixed with rubber, and preferably added in an amount of 0.2 to 5.0 pts.wt. relative to 100 pts.wt. of the rubber component. The especially preferred metallic material to be adhered with a rubber composition comprising this accelerator is a steel cord.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel cord adhesion promoter for improving the adhesion between rubber and steel cord, and to a rubber composition containing the same.

[0002]

2. Description of the Related Art Conventionally, in order to improve the adhesive force between a steel cord used as a reinforcing agent for a radial tire or a belt conveyor and a natural rubber or a synthetic rubber,
Cobalt-based compounds such as cobalt stearate, cobalt naphthenate, and cobalt-boron complex have been used as adhesion promoters. Cobalt-based compounds have a strong vulcanization accelerating ability, and rubbers containing cobalt have low storage stability, so metal salts other than cobalt-based ones have been studied. It has not yet been put to practical use. Recently, Japanese Patent Laid-Open Publication No. Hei 8-259740 discloses a rubber composition containing a cobalt salt of an organic acid and a metal salt of dithiophosphoric acid. However, in order to obtain good adhesive properties, mercaptotriazine is required. Was. Further, since dithiophosphate contains phosphorus in the molecule, it has a problem that when heated to a high temperature, it emits a bad smell, deteriorates the working environment, and lacks thermal stability.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an adhesion promoter which has improved adhesion, especially adhesion to a metal, until it is comparable to or higher than that of an organocobalt compound, and has improved storage stability. An object of the present invention is to provide a compounded rubber composition.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that in order to solve the above problems, one or more metallic soaps selected from nickel, zinc and zirconium are added to the organic cobalt compound. The inventors have found that they can be added, and have reached the present invention. That is, when one or more metallic soaps selected from nickel, zinc, and zirconium are added to the organic cobalt compound, excellent adhesive properties are exhibited as compared to the case of the organic cobalt compound alone, and the adhesive properties in high-temperature vulcanization and It has been found that the storage stability of the rubber after kneading is excellent.

That is, the present invention provides (1) a method of promoting adhesion between a metal and rubber, characterized in that an organic cobalt compound is blended with one or more metallic soaps selected from nickel, zinc and zirconium. And (2) a rubber composition comprising 0.1 to 10 parts by weight of the adhesion promoter described in (1) per 100 parts by weight of a rubber component.

The form of the organic cobalt compound used in the present invention is not particularly limited, and metallic soaps composed of fatty acids such as cobalt naphthenate, cobalt neodecanoate, cobalt stearate, cobalt-boron complex, cobalt Cobalt-containing compounds that have formed a salt with an organic substance, such as acetylacetonate, can be exemplified.

The fatty acid used in the metallic soaps of nickel, zinc and zirconium is not particularly limited, and is a saturated or unsaturated fatty acid having 2 to 30 carbon atoms or a mixture thereof, specifically propionic acid, butane Acid, hexanoic acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, arachidic acid, behenic acid,
Oleic acid, linoleic acid, linoleic acid, resinoleic acid, 12-hydroxystearic acid, dimer acid, tall oil acid, naphthenic acid, neodecanoic acid, resin acid, or those containing as a main component such as fish oil-hardened fatty acids, cow oil-hardened fatty acids, etc. And a metal soap formed with the natural oil fatty acid. Therefore, examples of metal soaps obtained by using these fatty acids include nickel naphthenate, zinc neodecanoate, zirconium tall oil and the like.

[0008] As a method for producing a mixed soap, it can be synthesized by a conventionally known metathesis method via an alkali metal soap, a direct method of directly reacting a metal compound with a fatty acid, or the like.

When adding the metallic soaps of nickel, zinc and zirconium and the organic cobalt compound to the rubber, they may be added after mixing them in advance, or they may be added separately.

[0010] The present invention is also a rubber composition characterized in that 0.1 to 10 parts by weight of the adhesion promoter is blended with 100 parts by weight of a rubber component.

In the present invention, the mixing ratio of the cobalt of the organic cobalt compound to one or more metallic soaps selected from nickel, zinc and zirconium relative to cobalt [(Ni, Zn, Zr) / Co metal weight ratio] Is
It is 0.01-20, preferably 0.05-10, and even more preferably 0.1-5. This mixing ratio is 0.01
If it is less than 30, the adhesive strength at the time of high-temperature vulcanization is not improved as compared with the case of using cobalt soap alone. On the other hand, if it exceeds 20, the adhesive strength decreases.

In the rubber composition of the present invention, natural rubber, synthetic isoprene rubber, and other diene rubbers such as styrene diene rubber and polybutadiene rubber can be mixed and used as rubber components. In particular, a rubber component containing 50% by weight or more of natural rubber and / or synthetic isoprene rubber is preferable.

In the rubber composition of the present invention, the adhesion promoter is used in an amount of 0.1 to 100 parts by weight of the rubber component.
It is preferable to add 10.0 parts by weight, preferably 0.2 to 5.0 parts by weight. If the amount is less than 0.1 part by weight, no improvement in the adhesive strength after vulcanization is observed.

Further, in the rubber composition of the present invention,
It is preferable that 3 to 8 parts by weight of sulfur is blended with respect to 100 parts by weight of the rubber component.

Further, the rubber composition of the present invention contains a filler such as carbon black or silica, a softener such as aroma oil, a sulfenamide based on diphenylguanidine, and a thiazole based on mercaptobenzothiazole. Vulcanization accelerators such as sulfenamides such as N, N-dicyclohexyldylsulfenamide and thiurams such as tetramethylthiuram disulfide;
In general rubber industry, anti-aging agents such as amine ketones such as poly (2,2,4-trimethyl-1,2-dihydroquinoline) and diarylamines such as phenyl-α-naphthylamine. The compounding agents used can be appropriately compounded in a usual compounding amount.

The kind and shape of the metal to be bonded to the rubber composition of the present invention are not particularly limited. However, a particularly preferred metal is steel cord. The metal is preferably plated with brass, zinc, or a metal containing nickel or cobalt in order to improve the adhesion to rubber, and is particularly preferably plated with brass.

[0017]

The present invention will be described below in more detail with reference to examples and comparative examples.

The cobalt content of Co neodecanoate used here is 10.1%, the nickel content of Ni neodecanoate is 10.5%, the zinc content of Zn neodecanoate is 17.7%, the neodecanoic acid The zirconium content of Zr used was 22.7%. Accel DZ-G (manufactured by Kawaguchi Chemical Co., Ltd., N, N-dicyclohexyl-2-benzothiazole sulfenamide) as a vulcanization accelerator, and Antage 6C (manufactured by Kawaguchi Chemical Co., Ltd.) as an anti-aging agent N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine) was used.

Test method: Each of the rubber compositions (unit: parts by weight) to which the amounts shown in Tables 1 and 2 were added were proficient with two test rolls to produce a 12 mm thick rubber sheet. Between this rubber sheet, brass (Cu about 70%,
A steel cord of 1 × 5 × 0.25 mm plated with Zn (about 30%) was embedded and vulcanized at 145 ° C. for 30 minutes to produce a rubber composition sample in which the steel cord was sandwiched.

For each of the obtained sheet samples, AS
A pull-out test was performed by a method according to TM-2229, and the adhesive strength between rubber and a steel cord and the rubber adhesion rate were measured. The results are as shown in Table 2.

As a comparative example, the same test was carried out for the case where bonding was performed using cobalt naphthenate, which is a conventional cobalt soap, and for the case where bonding was performed using zinc soap. The results are shown in Table 2. The adhesion test values shown in Tables 1 and 2 are shown as a coating ratio, which is a value expressed as an index with the ratio of the surface where the rubber remains adhered to the steel cord after the drawing is taken as an index with Comparative Example 1 being 100. Was. The higher the value, the better the result.

[0022]

[Table 1]

[0023]

[Table 2]

* 1: Normally, the vulcanization adhesiveness of the sample was 14
* 2: The high-temperature vulcanization adhesiveness was measured after vulcanizing the sample at 180 ° C. for 40 minutes after vulcanization at 0 ° C. for 20 minutes.

[0025]

As described above, in the adhesion promoter between metal and rubber such as steel cord of the present invention,
By adding an organic cobalt compound to one or more metal soaps selected from nickel, zinc, and zirconium to an organic cobalt metal compound, excellent adhesiveness compared to the conventionally used organic cobalt compound alone In particular, excellent adhesiveness can be obtained during high-temperature vulcanization.

Claims (4)

[Claims] 1. An adhesion promoter between a metal and a rubber, characterized in that one or more metal soaps selected from nickel, zinc and zirconium are mixed with an organic cobalt compound. 2. One or more metallic soaps selected from nickel, zinc, and zirconium are added to cobalt of an organic cobalt compound in a metal weight ratio [(Ni, Zn,
Zr) / Co] is 0.01 to 20, preferably 0.05 to
3. The adhesion promoter according to claim 1, which is blended in a ratio of 10. 3. The adhesion promoter according to claim 1, wherein the metal is a steel cord. 4. The method according to claim 1, wherein 100 parts by weight of the rubber component is used.
Or a rubber composition comprising 0.1 to 10 parts by weight of the adhesion promoter described in 2 above.