CS269081B1 - Rubber mixture with high adhesion to galvanized or brass-plated steel surfaces - Google Patents

Abstract

High-adhesion rubber compound to galvanized or plated steel surfaces based on butadiene-styrene, polyisoprene, polybutadiene or nitrile rubber or a combination thereof together with common ingredients and N, N'-m-phenylene bismaleinide contains maleic acid in an amount of 0.2 to 10 wt. Parts per 100 wt. rubber parts, wherein the ratio of maleimide amount and maleic acid is 50: 1 to 1: 50 cargo while keeping high adhesion values

Description

CS 269 081 B1 1

BACKGROUND OF THE INVENTION The invention relates to a rubber composition having high adhesion to galvanized or coated steel surfaces.

The rubber industry produces a large number of products consisting of rubber and metal, eg rubber elastic elements, tire casings with steel cord skeleton, steel rope conveyor belts, high pressure steel wire hose, etc. These articles require perfect bonding of the rubber with the metal, the second of the rubber-metal bonding methods being the use of a sulfur-containing rubber compound with brass applied to the steel. This method is still used today in the world. However, the application of a brass layer to steel is highly susceptible to changes in external conditions and difficult to control. Another method of rubber-metal bonding is the use of cyclo-rubber based adhesives, but adhesion decreases at slightly elevated temperatures. For galvanized sheets Systems based on halogenated rubber or isocyanate are used. The adhesions achieved with these adhesives are of a high standard, but their substantial drawback is their considerable toxicity, the necessity of using organic solvents and the uisocyanates in addition to their susceptibility to reaction with moisture, which greatly limit their use. The use of cobalt salts in rubber mixtures is a relatively widespread method. However, at the dosage required to achieve satisfactory adhesion values, the physico-mechanical properties of the rubber are reduced, aging is adversely affected and, last but not least, the tackiness is reduced. Other methods of modifying coating compositions are characterized by the addition of resorcinol, resorcinol formaldehyde resins or hexamethylentetramine to the rubber compositions. However, in higher temperature conditions, some systems experience a decrease in their original adhesion values.

Adhesives composed of isocyanates and some epoxy resins are used to bond natural and synthetic rubbers to hard materials, in particular U.S. Pat. No. 3,423,270. The adhesion effect is increased by the addition of 1 to 19 wt. fillers and a large surface area, e.g., carbon black, and addition of 1 to 10% by weight of maleic acid. The adhesion is applied as a solution in an organic solvent. The drawbacks of the method of bonding rubber to metal are known solvent systems, working with isocyanates. Obtained joint It is resistant to separation, hot water and chemical agents. __. U.S. Pat. No. 3,502,542 discloses a method of bonding rubber to metals that does not require special adhesives or acoustics and large amounts of sulfur. The rubber composition of the present invention comprises maleic acid derivatives and maleimide derivatives which chemically bind with the elastomer in the presence of free radicals and allow them to be highly adhered to the metal. The free radical source is a suitable organic peroxide and hydroperoxide. However, the high levels of adhesion achieved do not offset the cost of the peroxides used and the risks of working with peroxides.

The drawbacks and drawbacks of the prior art adhesive systems are removed by the rubber compound with high adhesion to galvanized or brass steel surfaces of the invention. SUMMARY OF THE INVENTION The invention is based on the fact that the rubber composition based on natural, butadiene-styrene, polyisoprene, polybutadiene or nitrile rubber or combinations thereof together with commonly used N, N * -m-phenylenebismaleimide (1,3-phenylene bis -1) 1 * - 1 H - pyrrole - 2.5 dione CS 269 081 B1 contains maleic acid (4 - amino - 4 - oxo - 2 - butenoic acid) in an amount of 0-2 parts by weight per 100% by weight. parts of rubber, wherein the ratio of the amount of amineimide to maleic acid is 50: 1 to 1: 50. The preferred amount of maleimide is 0.2 to 10% by weight. parts. The advantage of the rubber composition according to the invention lies in its high adhesion values to brass and galvanized steel surfaces and to a large extent to lower production costs. Indeed, maleic acid is an intermediate in the production of maleinide, so its cost compared to maleimide is lower. Thus, the use of maleamic acid in the rubber composition has reduced its cost while maintaining high levels of adhesion. The following examples serve to illustrate the invention in greater detail. Example 1

A rubber blend of the following composition was mixed:

natural rubber 100.0 wt. parts stearic acid 1.5 tt plasticizer 2.0 M ZnO 10.0 M retort carbon 65.0 M antioxidant 2.0 »» 1.2 M sulfur 3.0 W accelerator

The mixture was divided into several portions and N, N'-n-phenylenebismaleimide alone and in combination with maleic acid were mixed into these portions. From the above mixtures and brazed steel wire 7x4x0.22 + 1, test bodies were pressed in which the adhesion was measured by the ASTM method 0-2229-73. δ. 1.

Table 1

Maleimide masses, parts 100 wt. parts of rubber Maleic acid, parts 100 parts by weight of rubber Adhesion N / 25 mm 0 0 682 2 0 880 4 0 990 6 0 1 050 0 4 610 2 2 983

Claims (2)

EN 269 081 3 Example 2 The various amounts of N, N * m-phenylene-bismaleinimide and maleic acid were mixed into the same rubber mixture as in Example 1. \ t A test specimen was molded from the mixture and the galvanized steel cord 7 x 3 x 0.1. Measurement of adhesion was performed by method A ST M D-2229-72. The measured adhesion values in dependence on maleimide and maleamic acid concentrations in the rubber mixture are shown in Table 2. Table 2 Maleimide Mass 100 parts by weight Maleic Acid. SUMMARY OF THE INVENTION A rubber composition with high adhesion to galvanized or brass-coated steel surfaces, based on natural, butadiene-styrene, polyisoprene, polybutadiene or nitrile components. a rubber or a combination thereof comprising, in addition to conventional additives, Ν, Ν-m-phenylenebismaleimide, further comprising maleic acid in an amount of 0.2 to 10 wt. parts of rubber, wherein the ratio of maleimide to maleamic acid is 50 to 1: 50;