CS241291B1 - Rubber compound and high cohesion to viscose yarn - Google Patents

Abstract

Rubber mixture with high adhesion to viscose yarn based on butadiene-acrylonitrile rubber, butadiene-styrene rubber, chloroprene rubber or their combination, containing fillers, plasticizers, vulcanizing agents and other rubber additives, characterized in that it contains per 100 parts by weight of rubber 2 to 10 parts by weight of pre-polycondensed phenol-formaldehyde resin with a free phenol content of 4 to 6% by weight, 0.1 to 10 parts by weight of resorcinol and 0.3 to 2 parts by weight of hexamethylenetetramine.

Description

Prior to the disclosure, a rubber composition with high bonding strength to a viscose yarn based on butadiene acrylonitrile rubber, butadiene styrene rubber, chloroprene rubber or a combination thereof is particularly suitable for technical rubber articles reinforced with textile cords.

The reinforcement of technical rubber articles with textile cords presents problems in solving the cohesion of these materials to rubber compositions.

In the technical practice of the patent literature, compositions of adhesive rubber compositions are known which exhibit good cohesion with viscose, cotton, polyamide-based textile cords and the like. The problem is solved, for example, by the addition of polyisocyaners to the rubber mixture, e.g. USSR 462 831, the composition of a vulcanizing system based on peroxides e.g. USSR 462 831, Germany 2 642612.

At present, the most widespread adhesive system is a system based on resorcinol formaldehyde resins or resins with melamine resins designated as HRH. This issue is, for example, solved in the patents of the Federal Republic of Germany 3,003,934.

Belgium 857 253, Germany 2 407 660.

The HRH system consists of resorcinol, hexamethylenetetramine and active silicic acid; for ease of incorporation into rubber mixtures, resorcinol may be treated with other additives which also ensure its good dispersion in the mixture.

During the vulcanization of the adhesive mixtures, a polycondensax reaction occurs between resorcinol and a formaldehyde donor, releasing harmful pollutants which adversely affect human health. This system does not yet show the maximum values of cohesion, the significant aspect is also the economic aspect of resorcinins are imported from foreign exchange disadvantageous areas.

241 291

These drawbacks overcome the object of the present invention, which is a high-bonding rubber composition 3 to a viscose yarn based on butadiene acrylonitrile rubber, butadiene styrene rubber, chloroprene rubber or a combination thereof comprising fillers, plasticizers, vulcanizing agents and other rubber additives, comprising: . 2 to 10 wt. parts of a pre-polycondensated phenol-formaldehyde resin having a free phenol content of from 4 to 6 wt. % resorcinol and 0.3 to 2 wt. parts of hexamethylenetetramine.

By vulcanizing the rubber adhesive mixture to a viscose yarn, the same and higher cohesive values are obtained than with the HRH adhesive system. Importantly, the choice of a suitable type of pre-polycondensated phenol-formaldehyde resin with a free phenol content of 4-6% by weight, the adhesive effect decreases substantially when using resin types with a free phenol content of less than 4% by weight.

The small amount of resorcinol in the system, together with the effects of free phenol from the pre-polycondensated phenol-formaldehyde resin, acts as a catalyzing promoter for adhesive properties where oxidative disruption of the viscose yarn structure at vulcanization temperature causes greater hydroxyl reactivity and thereby more efficient chemical bonding reinforcement and rubber component. The adhesive effect is also partially enhanced by metalloconjugation of the pre-polycondensated phenol-formaldehyde resin with the type of rubber used.

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As a result of the complex process, cross-linking, metallising, and polycondensation reactions result in the formation of a three-dimensional sieve and chemical bonding of the rubber-viscose yarn system to form a resorcinol formaldehyde-phenol formaldehyde resin complex. It has been found that with a higher proportion of resorcinol in the system, the adhesive effect decreases, the resins behave as a semi-active filler. The formation of harmful pollutants is also reduced, the type of pre-polycondensated phenol-formaldehyde resin used requires substantially less formaldehyde donor to crosslink than resorcinin.

Also important in the adhesive system is the content of hexamethylenetetramine, which also acts as a secondary accelerator of the rubber component, the cohesion being also influenced by the type of rubber used. An optimum ratio of all components of the adhesive system is required for

4 211 291 determine each case experimentally. The object of the articles can be used in the manufacture of articles with higher technical-economical parameters reinforced with textile cords such as hoses, conveyor belts, preparation of adhesive mixtures and solutions for adhesives and the like. Said other applications are not to be construed as limiting the scope of the invention.

Example 1.

A mixture of the following composition was mixed from butadiene acrylonitrile rubber in combination with butadiene styrene rubber. parts

Butadiene acrylonitrile rubber containing 30 wt. acrylonitrile 80

Butadiene styrene rubber 20

Zinc oxide 10

Penylbeta naphthylamine 1

Stearic acid 1,5

Saze 120

Dibutyl phthalate 30

N-cyclohexyl-2-benzothiazolesulfenamide 1.5

Sulfur 1,5

The mixture was mixed in larger quantities and divided into 5 parts by weight in which the following adhesive ingredients were mixed.

mixture

No.1 No.2 No.3 No.4 No.5

Active silicic acid 20

Resorcinol ^x 3 'enolformaldehydolá předpolykondenzovanó resin free phenol content of 5% by weight. Penolformaldehyde pre-polycondensated resin with a free phenol content of 3% by weight.

Hexaraethylenetetramine 2.0

0,5 0,5

1,2 1,2

1,5 1,5

2,0 2,0

Ml 291

The dosage of the adhesive compositions is given in parts by weight per 100% by weight. parts of the rubber component in the mixture. Ze mixes

No. 1 to No. 5 test specimens were prepared for the cohesion test according to ČSN 62 1461 Cohesiveness of rubber layers with textile.

The viscose-based molino textile reinforcement samples were cured at 150 ° C for 30 minutes to an optimum pressure of 10 bar. In the cohesion tests the following values were measured in 'N.m' ^ mixture no.1 mixture no.2 mixture no.3 mixture no.4 mixture no.5 1 070 1 190 926 918 898

In the examples, a higher effect of the adhesive system according to the invention (mixture no. 2) can be observed.

Example 2.

A mixture of the following composition was mixed from chloroprene rubber. parts

Fireproof rubber 100

Zinc oxide 3,5

Magnesium oxide 5

Stearic acid 2,5

Penylbeta 1,5

Carbon black 40

Kaolin 20

Coumarone-indene resin 5

2-mercaptoimidazoline 0.5

Mineral oil 5

The mixture was mixed in larger quantities and divided into 5 parts by weight, in which the following adhesive ingredients were mixed, the dosages of the ingredients being given in% by weight. parts per 100 wt. rubber parts

- 6 241 291 mixture

No.6 δ.7 δ.8 No.9 No.1O

Active silicic acid 12

Resorcinol 3 Lenol formaldehyde prepolycondensed resin with a free phenol content of 5 wt.

Penolformaldehyde pre-polycondensated resin with a free phenol content of 3 wt. Hexamethylenetetramine 2

1 1.5 1.5

- 5

5-5 0.8 0.8 1 1

Sample preparation and cohesion tests were performed in the same manner as in Example 1. These values were measured in Nm ^-1 during the tests.

Mix No.6 Mix No.7 Mix S.8 Mix No.9 Mix No.10

230 1 236 1 039 1 126 996 In the above examples, a higher effect of the adhesive system according to the invention (mixture no.

Claims (1)

Object of the invention 241 291 High bonding rubber composition to a viscose yarn based on butadiene acrylonitrile rubber, butadiene styrene rubber, chloroprene rubber or combinations thereof, containing fillers, plasticizers, vulcanizing agents and other rubber additives, characterized in that it contains per 100 wt. 2 to 10 wt. parts of a pre-polycondensated phenol-formaldehyde resin having a free phenol content of from 4 to 6 wt. parts resorcinol and 0.3 to 2 wt. parts of hexamethylenetetramine.