RU2326903C1 - Zeolite-containing freeze-resisting rubber mix - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: rubber contains 17-23 mass % of acrylic acid nitrile. Rubber mix contains sulfur, zinc oxide, N,N-diphenylguanidine, carbon black "П803". In addition, 10.5-32.0 mass % of a polymer composition of ultra-high molecular weight polyethylene with natural zeolite in the mass ratio of 10-30:0.5-2.0 is inserted into the rubber mix. Natural zeolite undergoes mechanical activation beforehand.

EFFECT: higher frost and oil resistance of rubbers.

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Description

The invention relates to the rubber industry, in particular to the development of frost, wear, oil resistant rubber based on nitrile butadiene rubber SKN-18 for the manufacture of sealing parts used in moving parts of mechanisms operating at low temperatures.

It is known that for the manufacture of oil-resistant, wear-resistant cuffs and seals, rubber mixtures based on nitrile butadiene rubber are used [1].

Known rubber compounds based on nitrile butadiene rubber (BNKS-18), including fillers, vulcanization activators, vulcanization accelerators, softeners, dispersants and sulfur (other targeted additives may be added) [2]. At the same time, the technological properties of the rubber compound (ductility, extrusion, etc.) and the technical parameters of rubbers (strength characteristics, oil and oil resistance) are improved. However, rubbers based on BNKS-18 have low tribological performance and frost resistance.

Closest to the technical nature of the claimed mixture is a rubber mixture based on nitrile butadiene rubber with a nitrile content of acrylic acid of 17-23 wt.%, Including sulfur, N, N-diphenylguanidine, di- (2-benzothiazolyl) disulfide, zinc oxide, stearic acid, aldol-α-naphthylamine, N- (4-hydroxyphenyl) naphthylamine-2, N- (1,3-dimethylbutyl) -N′-phenylenediamine-1,4, carbon black P803 with a specific surface area of 12-18 m ² / g, dibutyl phthalate, molybdenum disulfide, β-sialon of the general formula Si _6-X Al _X O _X N _8-X , where x = 0.8 ÷ 4 and fluoroplast-4MB (prototype RU 2125068 C1, 1996 )

The disadvantages of the known rubber compound include insufficient frost and wear resistance.

The aim of the invention is to increase the frost resistance and wear resistance of nitrile butadiene rubber.

This goal is achieved in that the rubber mixture based on nitrile butadiene rubber with a content of acrylic acid nitrile of 17-23 wt.%, Including sulfur, N, N′-diphenylguanidine, di- (2-benzothiazolyl) disulfide, zinc oxide, stearic acid , aldol-α-naphthylamine, N- (4-hydroxyphenyl) naphthylamine-2, N- (1,3-dimethylbutyl) -N′-phenylenediamine-1,4, carbon black P803 with a specific surface area of 12-18 m ² / g , dibutyl phthalate, additionally contains, instead of molybdenum disulfide, β-sialon and fluoroplast-4MB, an ultra-high molecular weight polymer composition ethylene natural zeolite, subjected to mechanical activation in the following ratio, mass parts .:

Nitrile Butadiene Rubber acrylic acid 17-23 wt.% 100.00 Sulfur 2.45-2.65 N, N′-Diphenylguanidine 0.20-0.30 Di (2-benzothiazolyl) disulfide 2.6-2.8 Zinc oxide 7.40-7.60 Aldol-α-naphthylamine 3.80-4.20 N- (4-Hydroxyphenyl) naphthylamine-2 0.90-1.10 N- (1,3-Dimethylbutyl) -N′-phenylenediamine-1,4 0.80-1.20 Carbon black P803 128-132 Stearic acid 0.80-1.20 Dibutyl phthalate 18.0-22.0 Ultra high molecular weight polymer composition Polyethylene with natural zeolite subjected mechanical activation, with their mass ratio of 10-30: 0.5-2.0 10.5-32.0

The natural zeolite of the Khonguruu deposit of the Republic of Sakha (Yakutia) is a frame aluminosilicate, in the intracrystalline space of which are located exchange cations of alkali and alkaline-earth metals and water molecules.

Zeolites are also called molecular sieves, because their crystals have a developed system of pores and channels of molecular size, which determines their unique adsorption properties. The chemical composition of zeolite: SiO ₂ - 63-68%, Al ₂ O ₃ - 11-13%, Na ₂ O - 2-5%, CaO - 0.67-1.77%, TiO ₂ , Fe ₂ O ₃ , FeO - the rest. The general formula can be shown as follows:

Me _{2 / n} O · Al ₂ O ₃ · xSiO ₂ · yH ₂ O,

where Me is the cation of an alkali or alkaline earth metal, n is its valency.

The particle size is 1.6-4 microns, a density of 0.62-0.72 g / cm ³ .

Ultra-high molecular weight polyethylene (UHMWPE) is a white crystalline polymer (crystallinity of 49%) with a molecular weight of 2,000,000, which belongs to the class of high density polyethylene, has high frost, moisture, wear resistance, chemical inertness and a low coefficient of friction.

Before introducing into the elastomeric mixture, zeolites are calcined at a temperature of 450 ° C and a calcination time of 60 minutes. Then, to remove adsorption water, zeolites are subjected to mechanical activation, which occurs due to centrifugal forces when the drums rotate around the common and planetary axes of the AGO-2s mill (activation time - 2 min, motor shaft speed - 1450 rpm, drum speed - 1290 rpm). Activation leads to dispersion of particles and an increase in the structural activity of natural zeolite:

specific pore volume (cm ³ / g) increases by 1.3 times;

the specific geometric surface (m ² / g) increases by 1.5 times.

The calcined natural zeolites subjected to mechanical activation are introduced into a powdered ultra-high molecular weight polyethylene by dry mixing in a paddle mixer for 2-3 minutes. Thus, a polymer composition is obtained, which is then introduced on rollers into the rubber mixture for 5 minutes at a roll temperature of 50-60 ° C. Vulcanization is carried out at a temperature of 155 ° C for 20 minutes Exposure of vulcanizates to testing at least 6 hours. The composition of the rubber compounds are given in table 1.

Physico-mechanical parameters of vulcanizates are determined according to GOST 270-75, volumetric wear during abrasion according to GOST 25509-79, coefficient of frost resistance to elastic recovery after compression according to GOST 13808-79, the degree of swelling in a hydrocarbon medium according to GOST 9.030-74.

The properties of the vulcanizates are given in table.2.

Feasibility

The use of this invention can significantly increase the frost and wear resistance of rubbers, which will lead to an increase in the service life of seals made of these rubbers and used in friction units of machines and mechanisms operating at naturally low temperatures.

As can be seen from the above data, vulcanizates from a rubber compound of the claimed composition are superior to rubber from a known mixture (prototype): frost resistance increased by 1.2 times, volumetric wear during abrasion decreased by 1.2 times (i.e., wear resistance increased by 1, 2 times) while maintaining the level of tensile strength and oil resistance.

Information sources

1. Seals and sealing technique: Handbook. / Ed. A.I. Golubeva, L.A. Kondakova. - M.: Mechanical Engineering, 1986.- 464 p.

2. Fedyukin D.L., Makhlis F.A. Technical and technological properties of rubbers. - M .: Chemistry, 1985 .-- 217 p.

3. Chelishchev R.F., Berenstein B.G., Volodin V.F. Zeolites are a new type of mineral raw material. - M .: Nedra, 1987 .-- 176 p.

Table 1 The composition of the rubber compounds Ingredient Composition, parts by weight famous according to the invention control one 2 3 four 5 6 7 8 9 Nitrile butadiene rubber with acryl acid nitrile content of 17-23 wt.% 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Sulfur 2,5 2.45 2.65 2,50 2.45 2,50 2,50 2,50 2,50 N, N′-Diphenylguanidine 0.25 0.20 0.30 0.25 0.20 0.25 0.25 0.25 0.25 Di (2-benzothiazolyl) disulfide 2.7 2.60 2.80 2.70 2.60 2.70 2.70 2.70 2.70 Zinc oxide 7.5 7.40 7.60 7.50 7.40 7.50 7.50 7.50 7.50 Aldol-α-naphthalamine 4.0 3.80 4.20 4.00 3.80 4.00 4.00 4.00 4.00 N- (4-Hydroxyphenyl) naphthylamine-2 1,0 0.90 1.10 1.00 0.90 1.00 1.00 1.00 1,0 N- (1,3-Dimethylbutyl) -N′-phenylenediamine-1,4 1,0 0.80 1.20 1.00 0.80 1.00 1.00 1.00 1.00 Carbon black P803 130.0 128.0 132.0 130.0 128.0 130.0 130.0 130.0 130.0 Stearic acid 1,0 0.80 1.20 1.00 0.80 1.00 1.00 1.00 1.00 Dibutyl phthalate 20,0 18.0 22.0 20,0 18.0 20,0 20,0 20,0 20,0 Polymer composition of ultra-high molecular weight polyethylene with calcined natural zeolite subjected to mechanical activation 10.5 21.0 32,0 31,0 42.5 5.5 22.5 41.0

table 2 Properties of vulcanizates Indicator The rubber mixture according to examples famous according to the invention control one 2 3 four 5 6 7 8 9 Conditional tensile strength, MPa 13.8 12.9 13.5 14.2 14.5 10.6 13,2 11,4 9.8 Elongation at break,% 235 263 251 210 208 165 280 196 203 Coefficient of frost resistance by elastic recovery after compression, 20% at - 50 ° С 0.468 0.567 0.614 0.687 0.654 0.423 0.461 0.398 0.415 Volumetric wear during abrasion, cm ³ 0.131 0.105 0,086 0,048 0.056 0,120 0.162 0.141 0.128 The degree of swelling in oil AMG-10 at 70 ° C for 72 hours,% -0.018 -0.017 -0.016 -0.016 -0.015 -0.018 -0.020 -0.021 -0.016 Coefficient of friction 0.82 0.91 0.90 0.83 0.85 0.98 0.91 0.92 0.82

Claims (1)

A rubber mixture based on nitrile butadiene rubber with an acryl acid nitrile content of 17-23 wt.%, Including sulfur, N, N-diphenylguanidine, di- (2-benzothiazolyl) disulfide, zinc oxide, stearic acid, aldol-α-naphthylamine, N- (4-hydroxyphenyl) naphthylamine-2, N- (1,3-dimethylbutyl) -N-phenylenediamine-1,4, carbon black P803 with a specific surface area of 12-18 m ² / g, dibutyl phthalate, characterized in that it additionally contains a polymer composition of ultra-high molecular weight polyethylene with natural zeolite subjected to mechanical activation, when traveling ratio of components, parts by weight: nitrile butadiene rubber containing acrylic acid nitrile 17-23 wt.% one hundred sulfur 2.45-2.65 N, N′-diphenylguanidine 0.2-0.3 di (2-benzothiazolyl) disulfide 2.6-2.8 zinc oxide 7.4-7.6 aldol-α-naphthylamine 3.8-4.2 N- (4-hydroxyphenyl) naphthylamine-2 0.9-1.1 N- (1,3-dimethylbutyl) -N′-phenylenediamine-1,4 0.8-1.2 carbon black P803 128-132 stearic acid 0.8-1.2 dibutyl phthalate 18-22 ultra high molecular weight polymer composition polyethylene with natural zeolite subjected mechanical activation, with their mass ratio of 10-30: 0.5-2.0 10.5-32.0