SU633877A1 - Method of stabilizing siloxane rubber compounds - Google Patents

Description

This invention relates to methods for producing rubber from siloxane rubbers with highly active silica fillers, in particular, to the stabilization of rubber compounds from these rubbers. There is a known method of stabilizing raw rubber mixtures of siloxane rubbers in order to preserve their technological properties for a long time by introducing some organosilicate esters into the mixture, for example tetramethylethylenedioxydioxymethylsiloxane (PS-4). at high temperatures. Alkoxysilanes of the general formula (. ,,, where R is alkyl, cycloalkyl or aryl; R is alkyl or alkoxyalkyl; p is an integer 1-4. Alkoxysilanes Preferably in an amount of 5-10 parts by weight of rubber on cold rollers together with a filler and a vulcanizing agent. Additional processing of the mixture is not required. High fillers can be used as fillers for rubber mixtures with alkoxysylanes. Silicon dioxide active grades, for example, aerosil, BS-280 white carbon and others, are also added with low activity or inactive fillers. The mixtures obtained have good technological properties, are easily processed into articles by molding in molds and extrusion on syringes, easily calendered, and applied to fabrics. Such technological properties of mixtures are preserved for more than six months. In addition to stabilizing the technological properties of raw mixtures, alkoxysilanes, unlike PS-4, significantly increase heat resistance rubber, even without the introduction of a mixture of heat stabilizers. At the same time, the resistance of rubber to tearing and tearing increases, residual compressive deformations decrease at high temperatures and the elasticity of rubber increases.

Alkoxysilanes are clear, colorless, low odor liquids that are well preserved in a sealed package.

The examples show the use of alkoxysilanes as stabilizers of raw rubber mixtures of siloxane rubbers ..

PRI me R 1. 100 weight.h. SKTV-1 siloxane rubber is flared at a roll temperature of 20-30 ° C and added with 35 parts by weight Aerosil the right amount of methoxysilane. Then 0.4 parts by weight are introduced. dicumyl peroxide and bring the mixture to a uniform state. The prepared mixtures contain the following methoxysilanes listed in Table 1 and additives.

Technological properties of mixtures with 5 weight.h. methoxysilanes are stored for 7-10 days, with 10 parts by weight. - about 6 months, with a stabilizer of PS-4 about 3 months. .

Table 2 shows the properties of rubbers from these mixtures (vulcanization mode for 30 minutes in the press and b h at 200 ° C in a thermostat).

After heat aging at 250 ° C for 20 days, the rubber with methoxysilanes maintained satisfactory properties, while the rubber with PS-4 after three days of aging became brittle.

The technological properties of raw mixtures with small dosages of methoxysilanes are maintained for 7-10 days, in some cases, the physicomechanical properties of rubbers from them are improved, which makes it possible to use methoxysilanes in mixtures that cannot be stored for a long time.

Example 2. Rubber mixtures are prepared as in Example 1, using, instead of methoxysilanes, other alkoxysilanes in a dosage of 18 parts by weight. 100 weight.h siloxane rubber SKTV-1. The mixture is vulcanized in the usual way.

Table 3 shows the results of tests of these mixtures.

Table 1

Pre-aging properties

Stabilizer

strength, kg / cm

Table

Phenyltribute89 oxysilane

Methylphenyl- (2-methoxyethoxy) forces

Claims (1)

Phenyltri- (2-methoxyethoxy) -silums Claims of the invention A method for stabilizing rubber mixtures of siloxane rubbers containing highly active fillers by introducing into a mixture of organosilicon esters, characterized in that in order to increase the stability of the mixtures and heat-resist 63 200 2 450 77 2 400 81 and durability of rubbers, alkoxysilanes of the general formula R ,, 3 -, {ORM4-rt where R is alkyl, cycloalkyl or aryl; are used as the organosilicon esters; R is alkyl or alkoxyalkyl; n is an integer of 1-4.