RU2547477C2 - Oil-resistant rubber composition - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to preparation of a rubber composition based on hydrogenated butadiene-nitrile rubber with high content of acrylonitrile and low unsaturation and can be used in the rubber and industrial rubber industry to produce multilayer rubber-cord articles, used in conditions with dynamic loads, fuels and oils at high temperatures for a long period of time. The technical result is achieved by using, in the formulation of the rubber composition, a polymer base in the form of hydrogenated butadiene-nitrile rubber with high content of acrylonitrile (49-50%) and low unsaturation (5-7%), a vulcanising agent - sulphur donor in the form of N,N'-dithiodimorpholine, coupled with a dual system of high-activity vulcanisation accelerators, with the following ratio of components, pts.wt: hydrogenated butadiene-nitrile rubber with high content of acrylonitrile of 49-50% and low unsaturation (5-7%) - 100.0; ground sulphur - 0.1-0.3; technical carbon - 40.0-50.0; zinc oxide - 5.0-8.0; white soot - 5.0-20.0; plasticiser - 10.0-18.0; stearic acid - 0.5-1.5; diaphene FP-n/b 2.0; acetonanyl N - n/b 1.0; N,N'-dithiodimorpholine - 0.5-2.0; thiuram D - 0.6-1.5; sulphenamide C - 0.8-2.0. The invention increases oil and heat resistance and dynamic endurance of multilayer rubber-cord articles.

EFFECT: obtaining a rubber composition with high oil and heat resistance, high dynamic endurance, which enables rubber-cord articles to retain operational properties in aggressive media at high temperatures for a long period of time.

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Description

The invention relates to the creation of a rubber composition based on hydrogenated nitrile butadiene rubber with a high content of acrylonitrile and low unsaturation and can be used in the rubber and rubber industry for the manufacture of multilayer rubber-cord products operating under dynamic loads, fuels and oils at elevated temperatures during a long time.

Known rubber compound for fuel oil systems of motor vehicles (patent 2284338 RU, IPC C08L 19/00, C08K 3/06, publ. 06/03/2005), including epichlorohydrin rubber in combination with propylene oxide (50:50), sulfur, captax, tiuram, carbon black, plasticizer, zinc and magnesium oxides, Ni dibutyl dithiocarbomate as an antioxidant. The mixture has oil, heat, frost resistance, resistance to ozone and thermal aging.

A disadvantage of the known rubber mixture based on a combination of epichlorohydrin and propylene oxide rubbers is their low resistance to fuels, oils, thermal aging: the introduction of propylene oxide increases the frost resistance of the mixture, while reducing its oil and heat resistance.

Known vulcanizable rubber mixture based on hydrogenated nitrile butadiene rubber (GBNA) (patent 2304596 RU, IPC C08L 9/00, C08L 33/00, C08K 13/02, publ. 08.20.2007), including acrylate rubber, sulfenamide C, thiuram D, captax, zinc oxide, carbon black, plasticizer, antioxidant, release agent, as well as sulfur, quaternary ammonium base and metal stearate as vulcanizing agents. The mixture is intended for the manufacture of rubber parts capable of operating at temperatures up to 150 ° C.

A disadvantage of the known vulcanizable rubber mixture based on a combination of hydrogenated nitrile butadiene and acrylate rubbers is the need to carry out the vulcanization process in two stages, which significantly increases the duration of vulcanization of products from it.

The closest in technical essence and the technical result achieved is a vulcanizable rubber compound (patent 2380386 RU, IPC C08L 9/02, C08K 3/04, publ. 01/27/2010) containing hydrogenated nitrile butadiene rubber, carbon black, plasticizer, antioxidant, stearic acid and quinol ether as a vulcanizing agent. The mixture is intended for the manufacture of lip seals and other rubber goods operating in statics, for the oil production, oil refining industry and mechanical engineering.

A disadvantage of the known vulcanizable mixture is its low resistance to dynamic loads, insufficient oil resistance due to the use of GBNK with an acrylonitrile content of less than 50%, and the use of quinol ether only allows the vulcanization process to be carried out at lower temperatures.

The technical result of the invention is a rubber composition of increased oil and heat resistance, high dynamic endurance, which will ensure rubber-cord products maintain operational properties under the influence of aggressive environments at elevated temperatures for a long time.

The technical result is achieved through the use in the formulation of the rubber composition as the polymer base of hydrogenated nitrile butadiene rubber with a high content of acrylonitrile (49-50%) and low unsaturation (5-7%), as a vulcanizing agent - sulfur donor Ν, Ν ′ -dithiodimorpholine or sulfur in combination with a dual system of vulcanization accelerators of high activity - thiuram D and sulfenamide C in the following ratio of components, parts by weight:

Hydrogenated nitrile butadiene rubber with an acrylonitrile content of 49-50% and low unsaturation (5-7%) 100.0 Ν, Ν ′ - dithiodimorpholine 0.5-2.0 Ground sulfur 0.1-0.3 Dual high activity vulcanization accelerator system: thiuram D (tetramethylthiuram disulfide, imported analogue - vulcacite thiuram / C) 0.6-1.5 sulfenamide C (N-cyclohexyl-2-benzthiazolylsulfenamide, imported analogue - vulcacite CZ / EG-C) 0.8-2.0 Carbon black 40.0-50.0 Zinc white 5.0-8.0 White soot 5.0-20.0 Dibutyl phthalate 10.0-18.0 Stearic acid 0.5-1.5 Diafen FP (N-isopropyl-N′-phenyl-p-phenylenediamine, imported analogue - volcanox 4010 NA / LG) no more than 2.0 Acetononyl Η (2,2,4-trimethyl-1,2-dihydroquinoline) no more than 1,0

The applied components of the rubber composition are produced by the chemical industry of Russia, Ukraine and Germany. So, in the proposed rubber composition can be used hydrogenated nitrile butadiene rubbers of Therban brands (Lanxess (Germany), Zetpol of Νippon Zeon (Japan), Tornac of Polysar (Canada) - butadiene and acrylonitrile copolymerization products, the content of which in the initial mixture of monomers is 49-50%. The presence of acrylonitrile in an amount of 49-50% gives hydrogenated nitrile butadiene rubbers maximum oil resistance, and low unsaturation (5-7%) - high heat resistance.

The mixture is vulcanized by Ν, Ν′-dithiodimorpholine (TU U 24.1-32257423-121-2005) (Ukraine), which is a white cylindrical granule with a yellow tint and is used as a sulfur donor to increase resistance to thermal aging, or with gray ground ( GOST 127.4-93). Ν, Ν′-dithiodimorpholine and ground sulfur are most effective in combination with a dual system of vulcanization accelerators of high activity, vulcite tiuram / C (imported analogue of thiuram D) and vulcacite CZ / EG-C (imported analogue of sulfenamide C) from Lanxess. Vulcacite CZ / EG-C is a light gray granule with a melting point (t _PL ) not lower than 98 ° C. Vulcacite tiuram / C - white powder with t _PL not lower than 142 ° C. The vulcanization accelerators are activated by zinc white (GOST 202-84) and stearic fatty acids (GOST 6484-96), which is a translucent yellowish mass, greasy to the touch, with a _melting point of 53-63 ° С. The latter is also used to improve the dispersion of the ingredients of the rubber compound and facilitate its processing.

As fillers in the proposed composition used carbon black grades N550 (TU 38.41558-97) and K-354 (GOST 7885-77), used to improve the technological properties of rubber compounds and increase the physical and mechanical properties of vulcanizates, and white soot BS-120 ( GOST 18307-78), which is an amorphous white powder consisting of spherical porous particles. It is used to strengthen rubber compounds, increase heat resistance and dynamic endurance of rubber based on them.

As the plasticizer in the proposed rubber composition, dibutyl phthalate (GOST 8728-88) was used - phthalic acid dibutyl ether with a _{flash point of} at least 168 ° C, which in appearance was a colorless oily liquid.

Vulkanoks 4010 NA / LG (an imported analogue of AF diaphen) of the company "Lanxess" in appearance is a brownish lentil granules with t _PL not lower than 76 ° C. Acetononyl Η (TU 6-00-04691277-202-97) represents flakes or granules from light brown to dark brown in color with a _{mp of} at least 79 ° C. Both ingredients are used as antioxidants, antioxidants, rubber tackifiers.

The proposed and well-known rubber compositions were made in a laboratory rubber mixer (I and II stages) according to generally accepted technology. Vulcanization of the samples was carried out at a temperature of 153 ° C in the optimal mode. Physico-mechanical indicators of rubber were determined according to GOST 270-75 on standard equipment. The composition and properties of the proposed rubber composition in comparison with the prototype are presented in tables 1, 2. Examples 1 and 2 - known composition, examples 3-9 - the proposed composition.

In example 1 (prototype) make a rubber mixture based on 100 wt. including hydrogenated nitrile butadiene rubber with an acrylonitrile content of 34%. The mixture includes quinol ether as a curing agent, filler - carbon black brand P324, plasticizer - dibutyl phthalate, antioxidant - volcanox 4010 NA / LG.

According to example 2 (analogue), a rubber mixture is made based on 100 wt. including hydrogenated nitrile butadiene rubber with an acrylonitrile content of 34%. The mixture includes sulfur as a curing agent, thiuram D as a vulcanization accelerator, filler is carbon black P324, a plasticizer is dibutyloxyethyl adipate, and an antioxidant is phenyl-β-naphthylamine (naphtham-2).

In example 3, make an experimental rubber mixture based on 100 wt. including hydrogenated nitrile butadiene rubber with an acrylonitrile content of 49-50% brand Therban AT 5065 VP, which contains, by weight. hours: stearic acid - 1.5; zinc white - 5.0; BS-120 white soot - 20.0; dibutyl phthalate (DBP) - 10.0; acetonanil H - 1.0; Vulcanox 4010 NA / LG (imported analogue of AF diaphen) - 2.0; carbon black (TU) N550 (analogue of TU P514) - 40.0; TU K-354 - 10.0; Ν, Ν′-dithiodimorpholine - 0.6; vulcacite tiuram / C (imported analog of tiuram D) - 1.3; Vulcacite CZ / EG-C (imported analogue of sulfenamide C) - 1.3.

According to example 4, an experimental rubber mixture is made analogously to example 3, the difference is that отсутствует, Ν′-dithiodimorpholine is absent in the mixture, while the content, wt. h: vulcacite tiurama / C - 1.5; vulvacite CZ / EG-C - 0.8; ground sulfur is present in the mixture - 0.3.

According to example 5 (control), an experimental rubber mixture is made analogously to example 3, the difference is that the mixture does not contain Ν, Ν′-dithiodimorpholine, vulcite tiuram / C, vulcacite CZ / EG-C, acetonanil H - 1.0; volcanox 4010 NA / LG, TU K-354, the content, wt. hours: stearic acid - 0.5; white carbon black BS-120 - 5.0; DBP - 18.0; the mixture contains: percadox 14-40 BGR (imported analog of benzoyl peroxide) - 6.0; coagent of peroxide vulcanization TAIC (triallylisocyanurate) - 2.0; burnt magnesia - 5.0.

According to example 6, an experimental rubber mixture is made analogously to example 3, the difference is that the mixture does not contain TU K-354, while the content, wt. including: N, N′-dithiodimorpholine - 2.0; Tuliuram vulcite / C - 1.5; vulvacite CZ / EG-C - 0.8; zinc white - 8.0; white carbon black BS-120 - 10.0.

According to example 7, an experimental rubber mixture is made analogously to example 3, the difference is that in the mixture is present, wt. h: percadox 14-40 BGR-4.0; wherein the content of N, N′-dithiodimorpholine is 2.0; thiuram vulcacite / C - 0.6; vulvacite CZ / EG-C - 2.0; zinc white - 8.0; TU N550 - 30.0.

According to example 8, an experimental rubber mixture is made analogously to example 3, the difference is that in the mixture is present, wt. h: ground sulfur - 0.1; wherein the content of N, N′-dithiodimorpholine is 0.5; thiuram vulcacite / C - 1.0; vulvacite CZ / EG-C - 0.8; zinc white - 8.0; white carbon black BS-120 - 10.0; TU N550 - 30.0.

According to example 9, an experimental rubber mixture is made analogously to example 8, the difference is that the content, wt. hours, Ν, Ν′-dithiodimorpholine - 0.8; thiuram vulcacite / C - 1.2; ground sulfur - 0.2; white carbon black BS-120 - 5.0; DBP - 18.0.

The rubber test results presented in Table 2 (paragraphs 1-6) show that the rubber manufactured according to examples 3-9 are superior to the rubber made according to examples 1 and 2 (prototype and analog) in relative elongation at break, tear resistance, yielding value of conditional tensile strength. Since rubber-cord products operate in a dynamic mode, the determining factor is “fatigue endurance during repeated stretching”. All rubbers, with the exception of examples 5 and 6, have a high level of fatigue endurance, reaching maximum values in examples 7 and 8: samples after 1,800 thousand cycles were taken to failure.

The basis of the claimed rubber composition is hydrogenated nitrile butadiene rubber (GBNK) with an acrylonitrile content of 49-50%, which is superior in oil resistance to GBNN with an acrylonitrile content of less than 50%, which is part of the prototype rubber and similar rubber. This fact is confirmed by the results of mass swelling of the studied rubbers for a short time - in SZHR-1 (150 ° С × 3 days) and for a long time - in diesel oil М-14 В2 (125 ° С × 21 days): in both aggressive media the greatest changes in the indices of conditional strength and elongation are fixed in the rubber of the prototype and analogue (examples 1, 2) in contrast to the claimed composition (examples 3-9). The most resistant to aggressive environments is the claimed rubber, made according to example 8, in which the decrease in strength indicators occurred less intensively (change in conditional strength - plus 6.3%, relative elongation - minus 41.0%).

The degree of unsaturation (the content of double bonds in the polymer chain) of hydrogenated nitrile butadiene rubbers in the claimed rubber composition and in the prototype and analogue is almost the same (5-7% versus 4%). Therefore, in terms of resistance to thermal aging, the studied rubbers should be comparable. This is confirmed by the results of tests on resistance to aging in air at 150 ° C for 3 days (table. 2): the change in the relative elongation of the rubber of the prototype and analogue are similar to the claimed rubber composition, while the conditional strength of the rubber of the prototype and analogue is slightly reduced, in the claimed rubber - increases slightly. With an increase in the duration of the experiment to 21 days at 125 ° C, a decrease in the strength characteristics of the rubber of the prototype and analog occurs to a greater extent than in the claimed composition: minus 69.0% and minus 74.0% versus minus 56.6% - according to elongation; minus 22.5% and minus 29.0% versus plus 20.5% - for conditional strength. A change in the conditional strength indicator with a plus sign in the claimed rubber composition indicates that during the process of thermal aging in air, the structural reaction rate prevails over the destruction reaction rate (a change in the indicator with a minus sign in prototype and analog rubbers).

When solving the problem of creating a heat-resistant rubber composition, the choice of a vulcanizing group is important. In addition to antioxidants, the claimed rubber used sulfur donor Ν, Ν′-dithiodimorpholine and sulfur (in a low dosage) in combination with accelerators of high activity of vulcanicite thiuram / C and vulcanic CZ / EG- to increase heat resistance, resistance to thermal aging, and resistance to vulcanization reversal. C. The components of the vulcanizing group give the claimed rubber composition the greatest heat resistance.

Thus, the claimed rubber composition (example 8) has a balanced composition, has the best set of physico-mechanical properties before and after aging in air and in aggressive environments, has excellent dynamic properties (resistance to repeated deformations).

During prolonged use at elevated temperatures under the influence of aggressive environments and dynamic loads, rubber-cord products undergo aging and fatigue, as a result of which their physical and mechanical properties deteriorate, their stiffness and hardness increase, their elasticity and resistance to fracture decrease, and, ultimately, the product's service life generally. The use of the claimed rubber composition in multilayer rubber-cord products will increase their oil and heat resistance, dynamic endurance, and thereby ensure operability under conditions of exposure to dynamic loads, fuels and oils at elevated temperatures for a long time.

Claims (1)

A rubber composition intended for the manufacture of multilayer rubber-cord products operating under prolonged exposure to dynamic loads, fuels and oils at elevated temperatures, including ground sulfur, stearic acid, zinc white, carbon black, white carbon black, dibutyl phthalate, diafen FP and acetonanil N, in addition contains, as a vulcanizing agent, a sulfur donor или, Ν′-dithiodimorpholine or sulfur in combination with a double system of vulcanization accelerators of high activity, thiuram D and lfenamidom C, wherein as the polymer base used hydrogenated nitrile rubber with a high acrylonitrile content (49-50%) and small insaturation (5-7%) in the following ratio, wt. hours:
Hydrogenated nitrile butadiene rubber with an acrylonitrile content of 49-50% and low unsaturation (5-7%) 100.0 Ν, Ν ′ - dithiodimorpholine 0.5-2.0 Ground sulfur 0.1-0.3 Dual high activity vulcanization accelerator system: tiuram D 0.6-1.5 sulfenamide C 0.8-2.0 Carbon black 40.0-50.0 Zinc white 5.0-8.0 White soot 5.0-20.0 Dibutyl phthalate 10.0-18.0 Stearic acid 0.5-1.5 Diafen FP no more than 2.0 Acetononil Η no more than 1,0