CS222737B1 - Method of laying rubber vulcanizable compositions with zinc, zinc-coated or zinc-containing surfaces - Google Patents

Abstract

A method of joining a rubber vulcanizable mixture to zinc, galvanized or zinc-containing surfaces, in which a product of adsorption of colloidal silica and cobalt 2-ethylhexanoate or naphthenate is mixed into the rubber mixture containing the usual additives and the mixture thus prepared is vulcanized at elevated temperature and pressure onto a metal surface. The invention can be used in the production of conveyor belts with galvanized steel ropes, or in the production of tires with zinc-coated steel cord.

Description

The invention relates to a method of bonding rubber vulcanizable compositions with zinc-plated or zinc-containing surfaces.

When bonding rubber to zinc, galvanized or zinc-containing surfaces, for example, according to GDR patents Nos. 50,302, 50,303, USSR 107,337, Canada 1,024,835, Belgium Nos. 376,349 and Japan Nos. 54,052,188, rubber rubbers are mixed in vulcanizable mixtures of a cobalt complex compound of branched organic acids having a chain of 4 to 14 carbon atoms, and the mixture is then cured onto a metal surface. These cobalt compounds, when they contain 10 wt. and more, have the character of liquids having a relatively high viscosity, of the order of about 100 Pa. s. An essential part of these compounds is an organic acid, which then manifests itself as a plasticizer in the rubber mixture and, after vulcanization, also in rubber. It is known from experimental works that plasticizers in adhesive compositions have a negative effect on both the absolute adhesion values and the physical properties of the rubber. Therefore, these additives are dosed into the mixture as little as possible, but this is in contradiction with the requirement to achieve maximum adhesion at higher dosages. The high viscosity of these fluids is their adverse effect during the weighing, dispensing into the mixing device ¹ and when mixing into the rubber mixture. In the preparation of mixtures, this entails difficult dispersion, a considerable prolongation of handling and mixing times and increased demands on the hygiene of the work when dosing into ¹ mixing device. After their mixing, the stickiness of the rubber mixtures increases considerably, so that during their further processing considerable technological difficulties arise, especially when removing them from the rolling machines.

These drawbacks are eliminated when using the method of the invention for bonding rubber to metal. This is accomplished by mixing in a rubber mixture containing from 5 to 25 parts by weight of zinc oxide per 100 parts by weight of rubber and other conventional additives, fillers and vulcanizing agents an adsorption product of colloidal silica ¹ and 2-ethylhexanate or cobalt naphthenate with a total a cobalt content of 8 to 10%, in an amount of from 1 to 10 parts by weight of n and 100 parts by weight of rubber, and the rubber mixture thus prepared is cured to zinc, galvanized or surface-containing zinc. The vulcanization is carried out in a press at a temperature of 140 to 160 ° C and at a vulcanization pressure of at least 0.5 MPa. Said cobalt products are powdery preparations of violet and blue-gray color with a cobalt content of 8 to 10% and colloidal silica of 40 to 50%. They disperse very readily into rubber mixtures, they do not substantially affect the vulcanization characteristics.

By using the bonding method according to the invention, higher absolute adhesion values are achieved and the above mentioned handling and technological difficulties are eliminated. In particular, this will result in the preparation and processing of the compositions in improving hygiene conditions, shortening mixing times, improving dispersion, and reducing stickiness on rolling machines.

Invention can be used in the production of conveyor belts with galvanized steel cables, or ¹ in the manufacture of tires with steel cord pomosazeným.

The following examples illustrate the process of the invention.

Example 1

The mixture of natural and butadiene styrene rubber was mixed in a kneading machine with the following composition:

weight parts

Natural rubber 60.0

Butadiene styrene rubber 40.0

Zinc oxide 15,0

Stearic acid 1,0

Antioxidant 1.5

Carbon black (HAF, retort) 45.0

Aromatic oil 3.0

Lead Oxygen 1.5

Magnesium oxide 2.0

Sulphamide amide accelerator 0.75

Ground sulfur 2,6

The mixture was mixed in larger quantities and divided into 12 equal portions. Six parts were mixed in different amounts of cobalt 2-ethylhexanoate (cobalt content 9.2%) and the other six parts were mixed in different amounts with the product of colloidal silica and cobalt 2-ethylhexanoate (total cobalt content 9.2) O / o, colloidal silica content 45%) Both ingredients were mixed in the following amounts:

(a) 3,0 parts by weight of cobalt 2-ethylhexanoate

b) 4.0 parts by weight of cobalt 2-ethylhexanoate cj 5.0 parts by weight of cobalt 2-ethylhexianate dj 6.0 parts by weight of cobalt 2-ethylhexanoate

e) 8.0 parts by weight of cobalt 2-ethylhexanoate

f) 10.0 parts by weight of cobalt 2-ethylhexanoate aa) 3.0 parts by weight of colloidal silica and 2-ethyl cobalt 2-ethyl adsorption bb) 4.0 parts by weight of colloidal silica and cobalt 2-ethylhexanoate adsorption cc) 5.0 parts by weight of adsorption product of cobalt silicon dioxide and cobalt 2-ethylhexanate dd) 6.0 parts by weight of colloidal silica and cobalt 2-ethylhexanoate adsorption ee) 8.0 parts by weight of cotaid silica and 2-ethylhexanate fobate adsorption 10) 0 parts by weight of the product of adsorption of colloidal silicon dioxide and cobalt 2-ethylhexanoate

Test specimens for the determination of adhesion according to DIN 221131 (DK 621.867.21: 622.647) were molded from these simulations and galvanized steel ropes of 5.94 mm diameter.

. .21).

The rupture resistance of the rope from the test specimen in kN was determined on a shredder. m ^_1 . The following values were measured for individual mixtures:

Samples of the mixture:

aj - 95 kN. m- ¹ aa j - 96 kN. m ^_1 bj - 98 kN. M-1 bb) - 102 kN. rn ¹ c] - 100 kN. m “ ¹ cc) - 110 kN. me d) - 102 kN. mr ¹ dd) - 115 kN.m-i e) - 99 kN. m ^-1 ee) - 110 kN. me f) - 80 kN. m ^_1 ff) - - 108 kN. m- ¹

Example 2

According to Example 1, the base mixture was mixed, divided into 3 equal portions and mixed:

(a) 6 parts by weight of colloidal silica or cobalt 2-ethylhexanoate

b] 6 parts by weight of cobalt 2-ethylhexanoate and 2 parts by weight of tetrabromide silicon dioxide

Claims (1)

A process for bonding rubber vulcanizable compositions to zinc, zinc plated or zinc-containing surfaces, characterized in that the rubber composition comprises 5 to 25 parts by weight of zinc oxide per 100 parts by weight of rubber and other conventional additives, fillers and vulcanizing agents. mix the colloidal silica absorption product 6 parts by weight of cobalt 2-ethylhexanoate and 4 parts by weight of colloidal silica The test specimens were again pressed from these mixtures and galvanized steel ropes of 5.94 mm in diameter and the adhesion determined in accordance with DIN 22 131. The following values were found. Samples from the mixture: i - 116 kN. m- ¹ b) -101 kNm -1 (c) - 102 kN. m ^_1 Example 3 According to Example 1, the base mixture was mixed and divided into two equal parts of 1.5 kg. The laboratory twin cylinder was mixed with: (a) 6 parts by weight of cobalt 2-ethylhexanoate b) 6 parts by weight of the product of adsorption of colloidal silicon dioxide and cobalt 2-ethylhexanoate The time required to incorporate the above cobalt additives and the rubber additives into the rubber mixture was monitored. Time to smell: a) 3.5 minutes b) 1.5 minutes In general, a considerable number of other variations of these recipes can be used; and 2-ethylhexanoate or kbbaltate naphthalate having a total cobalt content of 8 to 10 percent, in an amount of from 1 to 10 parts by weight per 100 parts by weight of rubber, and the rubber mixture thus prepared is vulcanized at 140-160 ° C and pressure at least 0.5 MPa per metal surface.