RU2815100C1 - Frost-resistant rubber mixture based on butadiene-nitrile rubber - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to frost-resistant rubber based on butadiene-nitrile rubber, used for production of inner layer of high-pressure hoses (HPH) of winding structure used in hydraulic systems of mechanisms of Arctic equipment. Rubber mixture contains the following components: 80.0–90.0 wt.pts. of butadiene-nitrile rubber with acrylic acid nitrile (AAN) content of 17–23 wt.%, 10.0–20.0 wt.pts. of butadiene rubber, 3.5–4.5 wt.pts. of ground sulfur, 1.2–1.5 wt.pts. of altax, 0.7–1.2 wt.pts. of anti-scoring PVI, 2.5–3.0 wt.pts. of diaphene FP, 1.5–2.0 wt.pts. of acetonanil N, 3.5–5.0 wt.pts. of zinc oxide, 0.5–1.0 wt.pts. of stearic acid, 75–85 wt.pts. of technical carbon grade P 514, 10.0–20.0 wt.pts. of silicon dioxide with specific surface area of 100–120 g/m², 20.0–25.0 wt.pts. of kaolin treated with vinyltrimethoxysilane, 40.0–50.0 wt.pts. of calcium carbonate, 2.0–3.0 wt.pts. of pine rosin, and 7.0–10.0 wt.pts. of dibutyl sebacate plasticizer.

EFFECT: obtained rubber mixture has high frost resistance (up to minus 60 °C) while maintaining physical and mechanical properties of products at said operating temperatures, namely increasing Mooney viscosity, high viscosity of adhesion with brass-plated wire, high Shore hardness, while maintaining resistance to action of working fluids, tensile strength and relative elongation at break.

1 cl, 2 tbl, 2 ex

Description

Field of technology

The invention relates to the rubber industry, in particular to frost-resistant rubber based on nitrile butadiene rubber with a nitrile acrylic acid (NAA) content of 17-23 wt.% for the manufacture of the inner layer of high-pressure hoses (HPH) of a coiled structure used in hydraulic systems of arctic mechanisms technology.

Technical problem

The technical problem is to ensure the operability of the hose hose of the coiling structure in arctic conditions, namely at temperatures down to minus 60 ⁰ C. To solve this problem, it is necessary to develop a material - a rubber mixture from which the inner layer of the hose hose of the coiling structure is made - capable of withstanding loading without destruction at temperatures minus 60 ⁰ C and below (GOST 7912). In addition, this rubber compound must maintain the following characteristics:

- Mooney viscosity M _L1+4 (GOST 10722) – 90-110 units. to provide the technology for applying the RVD load-bearing frame

- Adhesion strength with brass-plated wire (GOST 14863) of at least 60 N - to ensure the integrity of the hose and uniform distribution of the internal pressure of the working fluid on the load-bearing power frame of the hose

- Resistance to the influence of working fluid - oil at a test temperature of 100 ⁰ C for 168 hours (GOST R ISO 1817) - change in sample weight no more than 60%; water and aqueous liquids at a test temperature of 70 ⁰ C for 168 hours (GOST R ISO 1817) - change in sample weight no more than 25% - to ensure the operability of the high-pressure motor when exposed to working fluids of hydraulic systems

- Tensile strength (GOST 270) – not less than 10.0 MPa – to ensure operation at increased operating internal pressure

- Elongation at break (GOST 270) - no less than 200% - to ensure the integrity of the hose when bending within the established standards (minimum bending radius)

- Shore hardness (GOST R ISO 7619) – 78…88 units. – to ensure flexibility and uniform distribution of internal pressure of the working fluid

The raw materials used for the rubber mixture being developed must be predominantly of Russian origin.

State of the art

Frost-resistant rubber compounds are known from the prior art, for example from RF patents No. 2522610, 2485147, 2747539, 2437903, 2125068, 2664405, 2688741, 2633892, 2550827. The disadvantages of rubber compounds according to these patents are: too low tensile strength, hardness, low strength clutches with brass-plated wire; low elongation at break, increased temperature limit of brittleness; use of imported rubbers, low hardness and viscosity.

Based on the scope of application of the invention (manufacture of the inner layer of high-pressure hoses (HPH) of a coiled structure), a close analogue is RF patent No. 2666442, published on 09/07/2018, describing rubber compounds based on nitrile-butadiene rubbers used for the manufacture of oil- and petrol-resistant hoses, including at low temperatures, and which has the following characteristics: Mooney viscosity 65-85 units, provided an increase in resistance to swelling in AMG-10 oil at a temperature of 100°C for 24 hours when changing weight to 5.4-7.5 % and a change in volume to 12.1-14.2%, ensured an increase in physical and mechanical properties at operating temperatures, namely, provided a conditional tensile strength of 18.5-22.0 MPa and elongation at break of 260-380% while maintaining operational hardness Shore A 66-70 Shore A units, while maintaining the temperature limit of brittleness at negative operating temperatures down to -48°C÷52°C and ensuring the frost resistance coefficient Kv for elastic recovery after compression at a temperature of minus 35°C within 0.48-0.51.

The specified achieved characteristics are insufficient to ensure the operability of the hose hose of the coiled structure in arctic conditions, namely at temperatures down to minus 60 ⁰ C, and do not correspond to the values specified in the “Technical problem” section.

The essence of the invention

The technical result achieved by implementing the claimed invention is an increase in the frost resistance of the rubber mixture (up to minus 60 ⁰ C) while maintaining the physical and mechanical properties of the products at the specified operating temperatures, namely an increase in Mooney viscosity, an increase in the viscosity of adhesion to brass-plated wire, and an increase in Shore hardness , while maintaining resistance to fluids, tensile strength and elongation at break.

The above technical results are achieved by the fact that the rubber mixture based on nitrile butadiene rubber contains components in the following ratio, parts by weight:

Nitrile butadiene rubber NAC 17-23 wt.% 80.0-90.0 Butadiene rubber 10.0-20.0 Ground sulfur 3.5-4.5, Altax 1.2-1.5, Anti-scorching PVI 0.7-1.2 Diafen FP 2.5-3.0 Acetonanil N 1.5-2.0 Zinc oxide 3.5-5.0 Stearic acid 0.5-1.0 Carbon black grade P 514 75-85, Silicon dioxide with a specific surface of 100-120 g/ ^m2 10.0-20.0 Kaolin treated with vinyltrimethoxysilane 20.0-25.0 Calcium carbonate 40.0-50.0 Pine rosin 2.0-3.0 Plasticizer dibutyl sebacate 7.0-10.0

The introduction of ingredients above or below the specified ranges of values leads to a deterioration in the output characteristics of the rubber compound.

A distinctive feature of the claimed invention is the composition of the above components introduced into the rubber mixture in an optimal quantitative ratio. This ratio of components makes it possible to ensure a synergistic effect of the technical result: to lower the temperature limit of brittleness of the rubber mixture below minus 60 ⁰ C while maintaining the remaining declared characteristics when using raw materials mainly produced in Russia.

Carrying out the invention

To obtain the rubber mixture, we used well-known materials, which are produced by enterprises of the chemical industry of the Russian Federation in accordance with the requirements of state standards and technical specifications:

- Butadiene-nitrile rubber brand BNKS-18 AMN 2 gr. – TU 38.30313-2006;

- Butadiene rubber SKD TU 38.403750-2001;

- Altax – GOST 7087-75;

- Anti-scorching PVI – CAS 17796-82-6 (import);

- Technical carbon P514 – GOST 7885-86;

- White soot BS-100 – TU 20.13.24-003-00203312-2021;

- Diafen FP (N-phenyl-N'-isopropylparaphenylenediamine) – TU 6-14-817-94;

- Acetonanil N – TU 2492-542-05763441-2013;

- Zinc whitewash (zinc oxide) – GOST 202-92;

- Ground sulfur – GOST 127.1-93;

- Stearin – GOST 6484-84;

- Calcium carbonate – GOST 12085-88;

- Kaolin treated with vinyl trimethoxysilane – TU 5729-10-40705684-2005;

- Dibutyl sebacate (DBS) – GOST 8728-88;

- Pine rosin – GOST 19113-84

The production of variants of the rubber mixture for the inner layer of the high pressure hose of the coiling structure (for compositions, see Table 1) was carried out on PD 320 160/160 rollers at a roller surface temperature of 40±5°C. Ingredient input sequence:

- rolled rubber BNKS-18 AMN 2gr. until a continuous “skin” is formed with a gap between the rollers of 1±0.5 mm;

- SKD rubber was introduced in small portions until a homogeneous mass was formed and the roller gap was adjusted so that there was a well-processed supply of the mixture between the rollers;

- then kaolin treated with vinyltrimethoxysilane, stearic acid, altax, zinc white, antioxidants, BS-100, anti-scorching PVI, pine rosin, ground sulfur were added and mixed with cutting by 2/3 of the roll and collecting spills until a homogeneous mass;

- then carbon black P-514 was introduced together with DBS, calcium carbonate with cutting by 2/3 of the roll and collecting spills to a homogeneous mass;

- final processing – three times at a gap between the rollers of 0.2 mm;

- total mixing time 30-35 minutes.

The unvulcanized rubber mixture was tested on an MV 3000 Basic viscosimeter.

Vulcanization of laboratory samples was carried out on a vulcanization press with heating plates 600×600 mm at a temperature of 160°C for 15 minutes with a pressure on the plunger of 7.0±0.2 MPa.

The characteristics of the obtained variants of rubber compounds according to the declared compositions are given in Table 2.

As can be seen from Table 2, the declared mixture meets all established requirements. Moreover, in terms of such characteristics as Mooney viscosity, adhesion strength to brass-plated wire, and Shore hardness, it is superior to the mixture known from the prior art, i.e. An increase in the frost resistance of the rubber mixture is achieved (up to minus 60°C) while maintaining the physical and mechanical properties of the products at the specified operating temperatures.

Table 1 - Compositions of rubber compound options

No. name of raw materials Mass parts Option 1 Option 2 1 Rubber BNKS 18 AMN 2 gr. 90.00 80.00 2 Rubber SKD/BR-1203 grade B 10.00 20.00 3 Carbon black P-514 75.00 85.00 4 Diafen FP 2.50 3.00 5 Acetonanil N 2.00 1.50 6 Altax 1.30 1.50 7 Anti-scorching PVI 1.20 0.70 8 Pine rosin 3.00 2.00 9 Kaolin treated with HTMS 25.00 20.00 10 Calcium carbonate (Mel MMC 1) 50.00 40.00 eleven Zinc whitewash 5.00 3.50 12 Stearic acid 0.50 1.00 13 White soot BS-100 20.00 10.00 14 Dibutyl sebacate (DBS) 7.00 10.00 15 Ground sulfur 4.50 3.50 TOTAL 297.00 281.70

Table 2 - Physical and mechanical properties of rubber.

No. Indicator name Standard Established norm Actual values Option 1 Option 2 1 Temperature limit of brittleness GOST 7912 Below -60°С -61 -63 2 Mooney viscosity M _L1+4 GOST 10722 90-110 units 93 95 3 Adhesive strength to brass-plated wire GOST 14863 not less than 60 N 96 82 4 Resistance to oil at a test temperature of 100 ⁰ C for 168 hours GOST R
ISO 1817 change in sample mass no more than 60% 51 56 5 Resistance to water at a test temperature of 70 ⁰ C for 168 hours change in sample mass no more than 25% 2.5 2.3 6 Resistance to aqueous liquids at a test temperature of 70 ⁰ C for 168 hours change in sample mass no more than 25% 1.8 2.6 7 Tensile strength GOST 270 not less than 10.0 MPa 12.6 11.4 8 Elongation at break at least 200% 286 253 9 Hardness Shore GOST R ISO 7619 78-88 units 82 80

Claims (2)

Frost-resistant rubber mixture based on nitrile butadiene rubber, characterized by the fact that it contains components in the following ratio, parts by weight: Nitrile butadiene rubber NAC 17-23 wt.%. 80.0-90.0 Butadiene rubber 10.0-20.0 Ground sulfur 3.5-4.5 Altax 1.2-1.5 Anti-scorching PVI 0.7-1.2 Diafen FP 2.5-3.0 Acetonanil N 1.5-2.0 Zinc oxide 3.5-5.0 Stearic acid 0.5-1.0 Carbon black grade P 514 75-85 Silicon dioxide with specific surface 100-120 g/ ^m2 10.0-20.0 Kaolin treated with vinyltrimethoxysilane 20.0-25.0 Calcium carbonate 40.0-50.0 Pine rosin 2.0-3.0 Plasticizer dibutyl sebacate 7.0-10.0