RU2714351C1 - Oil-heat-resistant elastomeric composition - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of an elastomeric composition based on hydrogenated butadiene-nitrile rubber with high content of acrylonitrile and low unsaturated and can be used in rubber and rubber industry for making rubber products, long-term operation in conditions of action of fuel and oil at high temperatures (up to 150 °C and higher). Hydrogenated butadiene-nitrile rubber with increased content of acrylonitrile (49–50.5 %) and extremely low unsaturation (up to 1 %) as polymer base in elastomer composition, as a vulcanising agent – organic peroxide or a mixture of peroxides in combination with a co-agent of peroxide vulcanisation, with the following ratio of components, pts. wt.: hydrogenated butadiene-nitrile rubber with acrylonitrile content of 49–50.5% and low unsaturation (up to 1 %) – 100.0; technical carbon N550 – 30.0–50.0; technical carbon N803 – 0–10.0, zinc oxide – 3.0–6.0; white soot – 5.0–10.0; dibutyl phthalate – 15.0–25.0; stearic acid – 0.5–1.0; magnesia – 5.0–10.0.

EFFECT: invention increases service life of rubber articles under conditions of aggressive media and high temperatures.

1 cl, 2 tbl

Description

The invention relates to the creation of an elastomeric composition based on highly saturated hydrogenated nitrile butadiene rubber with a maximum content of acrylonitrile and can be used in the rubber and rubber industry for the production of rubber products operated under the influence of fuels and oils at elevated temperatures (150 ° C and above) in for a long time.

Known vulcanizable rubber mixture based on hydrogenated nitrile butadiene rubber (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 hydrogenated nitrile butadiene and acrylate rubbers is the unsatisfactory technological properties, as well as the need for vulcanization in two stages, which significantly increases the duration of the vulcanization process of the products.

Known heat-resistant rubber mixture based on a combination of nitrile butadiene and partially hydrogenated nitrile butadiene rubbers (patent 2495061 RU, IPC C08L 9/02, C08K 13/02, publ. 10.10.2013), including carbon black, emollient, oligoester, antioxidant, stearic acid, burnt magnesia, processing aid, novoperox BP-40 as a curing agent, HVA-2 70GE deltagran as a co-peroxide vulcanization agent. The mixture is intended for the manufacture of rubber elements of packer-anchor equipment for the oil and gas industry, operable at temperatures up to 150 ° C.

A disadvantage of the known rubber mixture is the low heat and oil resistance due to the use of traditional nitrile butadiene rubber (BNK) with a temperature of operation up to 100 ° C in a mixture with partially hydrogenated nitrile butadiene rubber (GBNK).

The closest in technical essence and the achieved technical result is a rubber mixture based on hydrogenated nitrile butadiene rubber (Rubber and Rubber, 2007, No. 1, p. 4-7), including bis (tert-butyl peroxyisopropyl) benzene, coagent as a vulcanizing agent peroxide vulcanization (triallylisocyanurate - TAIC), dispersant, filler (carbon black P324), plasticizer (dibutyl ethyl ethyl adipate), antioxidant (naphtham-2).

A disadvantage of the known rubber mixture is that the mixture, having high resistance to elevated temperatures, is not able to withstand long-term contact with aggressive environments due to the use of GBNK with a low content of acrylonitrile (34%).

An oil-resistant rubber composition was investigated as an analogue (patent 2547477 RU, IPC C08L 9/02, C08K 3/04, 3/06, 3/22, 3/36, 5/09, 5/18, 5/40, 5/43 , 5/44, publ. 04/10/2015) based on GBNK with a high content of acrylonitrile (49-50%) and low unsaturation (5-7%), including carbon black, white soot, plasticizer, antioxidants, stearic acid, zinc white , ground sulfur and sulfur donor N, N ³ -dithiodimorpholine in combination with a double system of vulcanization accelerators. The mixture is intended for the manufacture of multilayer rubber-cord products operated under dynamic loads, fuels and oils at elevated temperatures.

A disadvantage of the known rubber composition is that the mixture, having maximum oil resistance, is not able to withstand the long-term effects of high temperatures: due to the use of a sulfur-containing vulcanizing system, the operating temperature of the rubber mixture is limited to 125 ° C.

As another analogue, the elastomeric composition was investigated (Patent 2680508 RU, IPC C08L 9/02, C08K 3/04, 3/22, 3.36, 5/09, 5/14, 5/18, 5/40, 5/43 , published February 21, 2019) based on a combination of partially and fully hydrogenated BNKs with a maximum acrylonitrile content (49-50%), with a low (up to 6%) and extremely low (up to 1%) degree of unsaturation, including carbon black, white soot , plasticizer, antioxidants, stearic acid, burnt magnesia, white zinc and sulfur-peroxide vulcanizing systems: N, N'-dithiodimorpholine in combination with thiuram D and sulfenamide C, perkadox 14-40 B-GR in combination with TAIC peroxide vulcanization coagent. The mixture is intended for the manufacture of multilayer rubber-cord products operated under conditions of dynamic loads, aggressive environments and high temperatures (up to 150 ° C).

A disadvantage of the known elastomeric composition is that vulcanizates with a sulfur-peroxide crosslinking system are less resistant to prolonged exposure to high temperatures due to the presence of sulfur in its composition.

The technical result of the invention is the creation of an elastomeric composition with increased oil and heat resistance, providing rubber products with no reversal of physical and mechanical properties under the influence of hydrocarbon media (fuel, oil) and high temperatures (150 ° C and above).

The technical result was achieved due to the fact that the polymer base of the elastomeric composition used hydrogenated nitrile butadiene rubber with a maximum acrylonitrile content (49-50.5%) and extremely low unsaturation (up to 1%), with a peroxide crosslinking system containing organic peroxide or a mixture of peroxides in combination with a peroxide vulcanization coagent in the following ratio of components, parts by weight:

hydrogenated nitrile butadiene rubber with an acrylonitrile content of 49-50.5% and extremely low unsaturation (up to 1%) 100.0 organic peroxide or mixture of peroxides 4.0-8.0 peroxide vulcanization coagent 2.0-4.0 carbon black 30.0-50.0 stearic acid 0.5-1.0 zinc white 3.0-6.0 burnt magnesia 5.0-10.0 white soot 5.0-10.0 plasticizer 15.0-25.0

The components used in the elastomeric composition are available in Russia and abroad. Thus, in the proposed rubber composition, Therban hydrogenated nitrile butadiene rubbers (GBNAs) from Arlanxeo (Germany) are used - copolymerization products of butadiene and acrylonitrile, the content of which in the initial mixture of monomers is 49-50.5%. The presence of acrylonitrile in the maximum amount (the upper limit of the specification) gives GBNK maximum oil and oil resistance, and extremely low unsaturation (up to 1%) - maximum heat resistance. These are the low-viscosity rubbers of the new generation, which have expanded the assortment of hydrogenated BNKs in recent years. Issues of formulation for this type of rubbers are not adequately addressed in domestic developments, their unique properties are practically unexplored, and a few studies are fragmented.

The mixture is vulcanized by organic peroxide or a mixture of peroxides, for example, 1,3-Di (tert-butyl peroxyisopropyl) benzene (perkadox 14-40 В GR, prospectus from Akzo Nobel, Netherlands; Novoperox BP-40, Samara Catalyst Plant, TU 2632-008- 02750395-2013), 2,5-Di (tert-butylperoxy) -2,5-dimethylhexane (peroxide DHBP-45-IC ₂ , prospectus from RT Vanderbilt, USA) or a mixture of peroxides. Perkadox 14-40 V GR is a yellowish solid wax-like substance with a slight odor with a density of 63 g / cm ³ , T _pl. 41 ° C, T _flash 90 ° C in an open crucible. DHBP-45-IC ₂ peroxide is a yellow liquid with a menthol odor with a density of 0.86 g / cm ³ , T _pl. 8 ° C, T _flash 46 ° C in an open crucible. Novoperox BP-40 is a grayish-white extrudate with T _pl. 105 ° C, T _flash 41 ° C in an open crucible. Peroxides during the vulcanization of the rubber compound form strong carbon-carbon cross-links between the rubber molecules, providing the vulcanizates with better resistance to thermal aging, lack of reversal of properties, and high heat resistance of the final product.

Obligatory components of peroxide vulcanizing systems, in addition to peroxides, are vulcanization coagents - low molecular weight compounds with several double bonds in the molecule. For crosslinking of GBNAs, allyl type vulcanization coagents triallylisocyanurate (TAIC) and triallyl cyanurate (TAC) are most preferred. TAIC (TU 2491-014-16993055-2007) - a colorless oily or slightly colored liquid or crystals with T _pl. 19-21 ° C, T _bales. not lower than 107 ° C, density 1.16 g / cm ³ , molecular weight 249.3. It crystallizes at temperatures below 25 ° C. TAC - colorless crystals with T _pl. not lower than 27 ° C, T _bales. not lower than 150 ° C. TAIC and TAC act as structuring agents and promoters of peroxide vulcanization.

As vulcanization activators use zinc white or zinc oxide (GOST 202-84) - white powder with a density of 5.47-5.66 g / cm ³ , insoluble in water, burnt magnesia or magnesium oxide (GOST 844-79) - powder white with a density of 3.20-3.70 g / cm ³ , insoluble in water, and a stearic fatty acid (GOST 6484-96), which is a powder or flakes of white, gray or yellowish tint with a density of 0.85-0, 99 g / cm ³ and T _pl. 53-63 ° C, greasy to the touch. 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 elastomeric composition using carbon black medium N550 (TU 38.41558-97) and low activity P803 (GOST 7885-86), used to improve the technological properties of rubber compounds and increase the physico-mechanical properties of vulcanizates, and white soot BS-120 or colloidal silicic acid (GOST 18307-78), which is an amorphous white powder consisting of spherical porous particles with a density of 1.85-2.15 g / cm ³ . It is used to strengthen rubber compounds, increase heat resistance and dynamic endurance of rubber based on them.

Fatty acid esters are used as a plasticizer in the proposed elastomeric composition, for example, phthalic acid dibutyl ether or dibutyl phthalate (GOST 8728-88) with a _{flash point of} at least 168 ° C, which in appearance is a colorless oily liquid.

Antioxidants are excluded from Therban AT 5005 VP-based rubber formulations, since the presence of fully hydrogenated, highly saturated macromolecular chains of BNKs and a peroxide vulcanizing system makes them less vulnerable to heat and oxygen.

In the inventive elastomeric composition can be used analogues of ingredients produced by various manufacturing companies.

The proposed and known elastomeric compositions are made in a laboratory rubber mixer (I and II stages) at a temperature in the chamber (30 ± 5) ° C. The rubber is loaded into a rubber mixer and treated for two minutes. Further, the manufacture of the rubber mixture is carried out according to generally accepted technology: at the first stage, activators, fillers, plasticizers are introduced, at the second - vulcanizing agents (peroxides) and peroxide vulcanization coagents. The vulcanization of the samples is carried out in a hydraulic press at a temperature of 160 ° C and a pressure of 20 MPa in the optimal mode, determined on a MDR 2000 rheometer from Alpha Technologies. The resulting vulcanizates have a smooth, uniform surface structure. Physico-mechanical properties of vulcanizates before and after aging in air, mass swelling in SZHR-1, engine oil M-14B _{2 are} determined on standard equipment by standard methods.

The composition and properties of the proposed elastomeric composition in comparison with the prototype and analogues are presented in tables 1, 2. Examples 1, 2, 3 - known composition, examples 4-8 - the proposed composition.

It is assumed that

- the maximum content of acrylonitrile in GBNK (49-50.5%) will increase the ability of rubbers to withstand prolonged exposure to aggressive environments at temperatures up to 150 ° C and above;

- extremely low content of residual double bonds (up to 1%) will provide them with maximum heat resistance, resistance to thermal aging in air and in aggressive environments;

- the presence of a peroxide crosslinking system will allow to obtain vulcanizates, without reversing the properties at a temperature of 150 ° C.

The present invention is illustrated by the description of examples 1-8.

In example 1 (prototype), a rubber mixture is made based on hydrogenated nitrile butadiene rubber with a share of Acrilonitrile 34% of Therban C3446 brand. The mixture contains bis (tert-butylperoxy-isopropyl) organic peroxide as a vulcanizing agent, triallyl isocyanurate as a vulcanization co-agent, P324 carbon black, plasticizer dibutyl ethyl ethyl adipate, antioxidant phenyl-β-naphthylamine (naphtham-2), dispersant.

In example 2 (analogue 1), a rubber mixture is made on the basis of hydrogenated nitrile butadiene rubber with a share of 49% Acrylonitrile brand Therban AT 5065 VP. The mixture contains ground sulfur and sulfur donor N, N'-dithiodimorpholine as vulcanizing agents, sulfenamide C, thiuram D as accelerators of vulcanization, fillers - carbon black N550 and white carbon black BS-120, plasticizer - dibutyl phthalate, antioxidants - acetonanil N and Diafen FP.

According to example 3 (analogue 2), an elastomeric composition is made based on a combination of hydrogenated nitrile butadiene rubbers with a share of 49-50% acrylonitrile of Therban AT 5065 VP and Therban AT 5005 VP grades taken, for example, in a ratio of 60:40. The mixture contains N, N'-dithiodimorpholine, thiuram / S vulcacite, CZ / EG vulcacite, perkadox 14-40 V GR and Novoperox BP-40, TAIC, stearic acid, zinc white, burnt magnesia, soot white, dibutyl phthalate, acetone Vulcanox 4010 NA / LG, carbon black N550.

In example 4, an experimental rubber mixture is made on the basis of 100 parts by weight of hydrogenated nitrile butadiene rubber with a share of acrylonitrile 49% brand Therban AT 5005 VP. The mixture contains ingredients, parts by weight: stearic acid-1.0; zinc white-4.0; burnt magnesia-8.0; white carbon black BS-120-10,0; dibutyl phthalate-25.0; carbon black N550-40.0; perkadox 14-40 V GR-6.0; TAIC-2.5.

According to example 5, an experimental rubber mixture is made analogously to example 4, the difference lies in the content of ingredients, parts by weight: stearic acid-0.5; zinc white-6.0; burnt magnesia-5.0; white carbon black BS-120-5.0; dibutyl phthalate-20.0; carbon black N550-50.0; perkadox 14-40 V GR-4.0; TAIC-2.0.

In example 6, an experimental rubber mixture is made analogously to example 5, the difference lies in the content of ingredients, parts by weight: zinc white-5.0; dibutyl phthalate-18.0; carbon black N550-40.0; perkadox 14-40 V GR-5.0; TAIC-3.0.

According to example 7, an experimental rubber mixture is made analogously to example 6, the difference lies in the fact that in the mixture are present, parts by weight: peroxide DHBP-45-IC ₂ -1,0; Novoperox BP-40-1.0; carbon black P803-10,0, with the content of perkadox 14-40 V GR-4.0; stearic acid-1.0; magnesia burnt-6.0; white carbon black BS-120-10,0; carbon black N550-30.0.

In example 8, an experimental rubber mixture is made analogously to example 6, the difference lies in the content of ingredients, parts by weight: stearic acid-1.0; zinc white-3.0; burnt magnesia-10.0; dibutyl phthalate, white carbon black BS-120-10.0 dibutyl phthalate-15.0; carbon black N550-50.0; perkadox 14-40 V GR-8.0; TAIC-4.0.

A distinctive feature of the proposed elastomeric composition is the use of highly saturated hydrogenated BNK with a maximum content of acrylonitrile and a peroxide crosslinking system. The novelty lies in increasing oil and heat resistance, maintaining physical and mechanical properties during aging in air and in aggressive environments for a long time, in a new combination of known components in the composition of the elastomeric composition.

Presented in table 2, the test results of rubbers (items 1-6) show that the proposed elastomeric composition made according to examples 4-8, in terms of nominal tensile strength inferior to the prototype and analogues (examples 1-3), superior to the prototype, but yielding to analogues in elongation at break and tear resistance.

The basis of the proposed elastomeric composition is GBNK with a maximum share of acrylonitrile (49%), which is superior in oil resistance to GBNK with a share of acrylonitrile 34%, which is part of the prototype rubber, and is on par with similar rubber. This fact is confirmed by the results of thermal aging of vulcanizates for a short time - in liquid SZHR-1 and engine oil M-14B ₂ (150 ° C × 3 days), for a long time - in oil M-14B ₂ (150 ° C × 21 days): in both environments the greatest changes in the indices of conditional strength and elongation are recorded in the rubber of the prototype (example 1) in contrast to analogues (examples 2, 3) and the proposed elastomeric composition (examples 4-8).

The degree of unsaturation (the content of residual double bonds in the molecular chain) of GBNK in the proposed elastomeric composition, unlike the prototype and analogues, is minimal (up to 1% versus 4% in the prototype, 6% in analogue 1, more than 1% in analogue 2). Therefore, in terms of resistance to thermal aging, the proposed elastomeric composition should exceed the rubber of the prototype and analogues. This is confirmed by the test results of the tested rubbers in air at 150 ° C during the day (table. 2): the change in the relative elongation of the prototype and analog 2 and the claimed rubber composition are almost the same, while the conditional strength of the rubber analogs and the claimed composition increases during aging, and the prototype rubber is reduced. With an increase in the duration of the experiment to 21 days, the decrease in the strength characteristics of the rubber of the prototype and analogues occurs to a greater extent, in contrast to the claimed composition: minus 64.2%, minus 91.5% and minus 85.0% against (minus 37.7 ÷ minus 45.9%) - according to elongation; 23.8%, 26.5% and 21.5% versus 14.0 ÷ 20.3% - by conditional strength. A change in indicators with a plus sign indicates that during thermal aging in air, the rate of structuring reaction prevails over the rate of destruction reaction (change in indicator with a minus sign).

When solving the problem of creating a heat-resistant elastomeric composition, the choice of a vulcanizing system is important. In the proposed composition, organic peroxides were used in combination with a peroxide vulcanization coagent, which made it possible to obtain vulcanizates that for a long time retain strength characteristics at a high level when aging in air and in aggressive environments at a temperature of 150 ° C, i.e. no properties are reversed in peroxide vulcanizates. The components of the vulcanizing system give the claimed elastomeric composition the greatest heat resistance.

Thus, the claimed elastomeric composition has a balanced composition, has the best set of physico-mechanical properties before and after aging in air and in hydrocarbon media.

During prolonged use at elevated temperatures under aggressive environments, products undergo aging, as a result of which their physical and mechanical properties deteriorate, stiffness and hardness increase, elasticity and resistance to fracture decrease and, ultimately, the life of the product as a whole . The use of the claimed elastomeric composition will increase the oil and heat resistance of rubber products, and thereby ensure long-term performance when operating under the influence of fuels and oils at elevated temperatures (150 ° C and above).

Claims (2)

An elastomeric composition for the manufacture of rubber products operating under prolonged exposure to fuels and oils at elevated temperatures, including hydrogenated nitrile butadiene rubber, stearic acid, zinc white, carbon black, plasticizer, organic peroxide in combination with a peroxide vulcanization coagent, characterized in that additionally contains burnt, white soot magnesia, while rubber with the maximum content is used as hydrogenated nitrile butadiene rubber Niemi acrylonitrile (49-50,5%) and extremely low insaturation (1%), in an organic peroxide mixture may be used peroxides the following component ratio, mass parts .: hydrogenated nitrile butadiene rubber with the content of acrylonitrile 49-50.5% and extremely low unsaturation (up to 1%) 100.0 organic peroxide - perkadox14-40 BGR or a mixture of peroxides - perkadox14-40 BGR, DHBP-45IC ₂ , Novoperox BP-40 4.0-8.0 peroxide vulcanization coagent -TAIC 2.0-4.0 carbon black N550 30.0-50.0 N803 0-10,0 stearic acid 0.5-1.0 zinc white 3.0-6.0 burnt magnesia 5.0-10.0 white soot 5.0-10.0 plasticizer - dibutyl phthalate 15.0-25.0