Low-temperature-resistant hydrogenated butadiene-acrylonitrile rubber for oil field and preparation method thereof

Abstract

The invention discloses low-temperature-resistant hydrogenated butadiene-acrylonitrile rubber for an oil field and a preparation method of the low-temperature-resistant hydrogenated butadiene-acrylonitrile rubber for the oil field, the preparation method comprises the following steps: preparation of a reaction type macromolecular long-chain grafting agent, preparation of long-chain branched butadiene-acrylonitrile rubber and preparation of the low-temperature-resistant hydrogenated butadiene-acrylonitrile rubber for the oil field, and the reaction type macromolecular long-chain grafting agent has the following structure: # imgabs0 #, r is straight chain alkyl of C6 to C12; m and n are repetitive unit numbers, n is a positive integer greater than or equal to 1, and m is a positive integer greater than or equal to 1; the number-average molecular weight (Mn) of the reaction type macromolecular long-chain grafting agent is 4000 to 6000. The preparation method of the low-temperature-resistant hydrogenated butadiene-acrylonitrile rubber for the oil field has the characteristics of environment friendliness, efficient and stable modification effect, low addition proportion, commercially available and easily available raw materials, suitability for industrial production and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber, and in particular relates to a low-temperature resistant hydrogenated nitrile rubber modified by a macromolecular long-chain branching agent and a preparation method thereof. Background Art

[0002] Hydrogenated nitrile rubber (HNBR for short) is prepared by selective hydrogenation of carbon-carbon double bonds in nitrile rubber. Therefore, HNBR not only retains the oil resistance, corrosion resistance and elasticity of NBR, but also exhibits excellent aging resistance and high temperature resistance. The mechanical properties such as tensile strength, elongation at break, wear resistance and hardness are improved. It is widely used in oil exploration equipment such as pump pistons, rotary hoses, valve seals, drill pipe shields, etc.

[0003] Although hydrogenation of carbon-carbon double bonds gives HNBR very excellent performance, it also brings a serious defect to HNBR materials. The main chain of hydrogenated nitrile rubber (NBR) is a highly ordered polyethylene structure, which is very easy to form a crystalline structure and causes an increase in Tg. Therefore, the low-temperature resistance of HNBR products is poor. Since most of my country's oil drilling business is concentrated in the western and northeastern regions, the lowest temperature in these regions can reach about -50℃. Oil drilling equipment faces an application environment under low temperature conditions, which puts forward extremely high requirements on the low-temperature resistance of rubber sealing materials.

[0004] In the prior art, there are many patent documents reporting on the preparation method of low temperature resistant hydrogenated nitrile rubber. For example:

[0005] CN 106349410 B discloses a special hydrogenated nitrile rubber with compression cold resistance and a preparation method thereof, wherein the rubber main chain contains epoxy groups, and part of the epoxy groups are also connected to ester side groups; the ester side groups are generated by the ring-opening reaction of C6-C24 acid anhydride and the epoxy groups. The preparation method comprises introducing epoxy groups into the main chain of the rubber molecule, and then reacting part of the epoxy groups with acid anhydride under the action of a catalyst to introduce ester groups, thereby obtaining a special hydrogenated nitrile rubber containing epoxy groups and ester groups. CN 105294939B discloses a low-temperature grade hydrogenated nitrile rubber raw rubber, which is a copolymer of butadiene, acrylonitrile and dibutyl fumarate, and the number average molecular weight of the copolymer is 1.05 to 3.25×10 5 , weight average molecular weight is 3.02~9.32×10 5, the polydispersity coefficient is 2.0-2.7; the low-temperature grade hydrogenated nitrile rubber raw rubber has a hydrogenation degree of more than 90% and a glass transition temperature of -38°C to -42°C. CN 112592461 B discloses a modified hydrogenated nitrile rubber material with the characteristics of low temperature resistance and high damping, and its preparation method and application. The modified hydrogenated nitrile rubber material is prepared using HNBR / PNB block copolymer as raw material; the HNBR / PNB block copolymer is obtained by modifying NBR or HNBR through olefin metathesis reaction using norbornene monomer as a modifier. CN 115594898A discloses a low-temperature resistant hydrogenated nitrile rubber compound and a banburying preparation method thereof, which mainly comprises blending and banburying hydrogenated nitrile raw rubber, a plasticizer and a hardness regulator, and finally obtaining a low-temperature resistant hydrogenated nitrile rubber compound having a Shore A hardness of 67±5, a tensile strength ≥14MPa, an elongation at break ≥180%, a compression permanent deformation ≤35%, and a 45°C compression cold resistance coefficient ≥0.16. CN 105754164A discloses a low-temperature resistant rubber material, although the low-temperature resistance of the material is improved, the addition of the plasticizer dioctyl phthalate (DOP) reduces the mechanical properties and oil resistance of the material, and DOP is not environmentally friendly and is easy to precipitate. Zhang Dongheng et al. disclosed that ethylene propylene rubber (EPDM) and HNBR were blended to improve the low temperature performance of HNBR. When the EPDM addition amount was 15%, the Tg decreased by 3°C. However, when the EPDM addition amount was further increased, the Tg of the blended rubber did not decrease any more (Synthetic Rubber Industry, 2002, 25(1): ).

[0006] In the above-mentioned prior art, although the low temperature resistance of hydrogenated nitrile rubber can be improved to a certain extent by adding small molecule modifiers, copolymerization and blending, these methods still have certain limitations, and the preparation methods thereof have the problems of complex process, difficulty in actual operation, large addition amount, high cost, and unclear modification effect. Summary of the invention

[0007] In order to solve the problems existing in the prior art, the present invention provides a method for preparing low-temperature grade hydrogenated nitrile rubber with a hydrogenation degree of more than 96% and a glass transition temperature Tg of the raw rubber <-49°C, which can meet the use requirements within the range of -49°C to -53°C. The invention first adopts coordination polymerization to prepare a reactive macromolecular long-chain grafting agent with free radical reaction activity by reacting the reaction monomer long-chain α-olefin with ethylene under the action of a nickel-based complex catalyst; then the reactive macromolecular long-chain grafting agent is grafted onto the main chain of the nitrile rubber to prepare a long-chain branched nitrile rubber; finally, the long-chain branched nitrile rubber is subjected to a hydrogenation reaction to prepare a low-temperature resistant hydrogenated nitrile rubber for oil fields. The method solves the problem that nitrile rubber is easy to crystallize during the hydrogenation process, thereby causing the glass transition temperature Tg to increase, so that the hydrogenated nitrile rubber shows very excellent low-temperature resistance, and is very suitable for oil well operations under low-temperature conditions of -49°C.

[0008] Unless otherwise specified, the "parts" described in the present invention refer to parts by mass, the "%" described refers to mass percentage, and the "ratio" described refers to mass ratio.

[0009] In order to achieve the above object, the present invention provides a method for preparing low-temperature resistant hydrogenated nitrile rubber for oil field, the preparation method comprising the following steps:

[0010] (1) firstly, introducing an inert gas into a reaction kettle for replacement, adding a solvent, raising the temperature, adding an alkylaluminoxane co-catalyst under stirring, continuing stirring under the protection of the inert gas, then adding a nickel-based complex catalyst and a long-chain α-olefin and introducing ethylene to start the reaction; after the reaction is completed, centrifugation and drying are performed to obtain a reactive macromolecular long-chain grafting agent;

[0011] (2) dissolving the nitrile rubber in a chlorobenzene solution to prepare a glue solution, then adding the glue solution into a reactor, introducing nitrogen for replacement, then adding a reactive macromolecular long-chain grafting agent into the reactor, stirring and mixing, heating, then adding a mixed solution of an initiator and chlorobenzene, reacting, and after the reaction is completed, flocculating, washing, and drying to obtain a long-chain branched nitrile rubber;

[0012] (3) dissolving the long-chain branched nitrile rubber in a solvent to prepare a rubber solution, then adding the solution into a reactor to remove the air in the reactor by introducing an inert gas, then removing the inert gas in the reactor by using hydrogen, adding a xylene solution of a Grubbs II catalyst under nitrogen protection, pressurizing and heating, reacting, cooling, condensing, and drying to obtain a low-temperature resistant hydrogenated nitrile rubber for oil fields;

[0013] The reactive macromolecular long chain grafting agent has the following structure:

[0014]

[0015] Among them, R is C6~C12 m and n are the number of repeating units, n≥1, and m≥1; the number average molecular weight (Mn) of the reactive macromolecular long-chain grafting agent is 4000-6000.

[0016] The long-chain α-olefin described in the present invention is a C6-C12 straight-chain olefin, which can be selected from 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene and 1-dodecene, preferably 1-octene.

[0017] The nickel-based complex catalyst of the present invention is selected from one of (1-naphthyl)〔8-(diphenylphosphino)quinoline〕nickel chloride, trans-phenyl(bis(triphenylphosphine))nickel bromide and 2,5-diformylpyrrole nickel dibromide, preferably trans-phenyl(bis(triphenylphosphine))nickel bromide.

[0018] The alkylaluminoxane cocatalyst of the present invention is selected from one of methylaluminoxane (MAO) and ethylaluminoxane (EAO), preferably methylaluminoxane.

[0019] In step (1) of the present invention, the mass ratio of the solvent, the alkylaluminoxane co-catalyst, the long-chain α-olefin and the nickel-based complex catalyst is 300-500:10-20:20-30:1.

[0020] In step (1), the temperature is raised to 70-90° C., the rotation speed is 500-700 rpm, and the stirring time is continued for 15-30 min.

[0021] In step (1), the reaction pressure is 10-15 MPa, and the reaction time is 3.0-6.0 hr.

[0022] The initiator described in the present invention is an organic peroxide, selected from one of diacetyl peroxide, diisobutyryl peroxide, cumene hydroperoxide, dicumyl peroxide (DCP) and dibenzoyl peroxide, preferably dicumyl peroxide (DCP), and the amount of the initiator added is 0.01-0.1 part, preferably 0.03-0.05 part, based on 100 parts of the mass of the nitrile rubber.

[0023] The nitrile rubber of the present invention is copolymerized by emulsion polymerization of 1,3-butadiene and acrylonitrile, wherein the acrylonitrile content of the nitrile rubber is 20wt% to 42wt%, preferably 22wt% to 35wt%.

[0024] In step (2) of the present invention, the mass fraction of the glue solution is 5% to 7%.

[0025] In step (2) of the present invention, the mass ratio of the reactive macromolecular long chain grafting agent, chlorobenzene and nitrile rubber is 5 to 7:50 to 100:100.

[0026] In step (2) of the present invention, the grafting rate of the long-chain branched nitrile rubber is 3.8% to 4.9%.

[0027] In step (2) of the present invention, the heating temperature is 70-80° C. and the reaction time is 6.0-7.0 hr.

[0028] The solvent of the present invention can be selected from one of cyclohexane, carbon disulfide (CS2), nitrobenzene, petroleum ether, tetrachloroethane, toluene and xylene, preferably xylene.

[0029] In step (3) of the present invention, the mass ratio of the long-chain branched nitrile rubber to the Grubbs II catalyst is 100:0.1-0.5.

[0030] In step (3) of the present invention, the mass fraction of the glue solution is 3% to 10%; the mass concentration of the xylene solution of the Grubbs II catalyst is 5% to 10%.

[0031] In step (3) of the present invention, the pressure is increased to 6-10 MPa, the temperature is increased to 80-110° C., and the reaction time is 8-10 hr.

[0032] The polymerization reaction of the present invention is carried out in an oxygen-free, water-free and inert gas environment. The inert gas is nitrogen or a gas of a Group 0 element in the periodic table except radon, preferably nitrogen.

[0033] The reactor described in the present invention can be a loop reactor or a tank reactor, preferably a tank reactor.

[0034] The pressurization in step (3) of the present invention is achieved by adding hydrogen. The amount of hydrogen added is well known to those skilled in the art and is within the conventional addition range in the prior art, and is not particularly limited in the present invention.

[0035] The present invention also provides a low-temperature resistant hydrogenated nitrile rubber for oil fields obtained by the preparation method.

[0036] Compared with the prior art, the present invention has at least the following advantages and beneficial effects:

[0037] (1) The reactive macromolecular long-chain grafting agent prepared by the present invention forms a macromolecular chain from long-chain α-olefins through coordination polymerization, and is activated by ethylene to make it have free radical reaction activity, so that it can be grafted onto nitrile rubber to form a long-chain branched structure on the main chain structure of nitrile rubber. This structure can significantly destroy the highly saturated hydrocarbon structure of HNBR with a low addition amount, effectively reduce the crystallinity of HNBR, greatly reduce the glass transition temperature (Tg) of hydrogenated nitrile rubber, and prepare a low-temperature grade hydrogenated nitrile rubber with Tg<-49°C.

[0038] (2) The long-chain branched nitrile rubber prepared by the present invention fully utilizes the "structural stacking effect" of the long chain branches while ensuring the degree of hydrogenation, greatly improving the low-temperature resistant modification effect, and can meet the use requirements of rubber sealing materials for oil drilling equipment under the low temperature conditions of the lowest temperature of -49°C to -53°C.

[0039] (3) The preparation method of the low-temperature resistant hydrogenated nitrile rubber for oil fields of the present invention is green and environmentally friendly, has efficient and stable modification effect, has a low addition ratio, and has readily available raw materials on the market, and is suitable for industrial production. DETAILED DESCRIPTION

[0040] The following examples and comparative examples are listed to illustrate the effects of the present invention, but the protection scope of the present invention is not limited to these examples and comparative examples. The raw materials used in the examples are all industrial grade and used after purification without other special requirements. The "parts" described in the examples and comparative examples are all parts by mass.

[0041] (1) Source of raw materials:

[0042]

[0043] (2) Analytical testing methods:

[0044] Determination of grafting rate: Take about 4g of sample from the three-necked bottle with a pipette and put it into a weighing bottle. After weighing, add 2-3 drops of hydroquinone solution and dry to constant weight. Then put the sample in a Soxhlet fat extractor and extract it with toluene in a 90℃ water bath for 24 hours, and then dry it to constant weight. Calculate the monomer grafting rate according to the following formula:

[0045]

[0046] Where: m0 is the total mass of the mortar (g); m is the mass of the sample weighed after the reaction (g); m —Total mass of monomers in the reactants (g); m NBR —The mass of nitrile rubber in the sample (g); m1—The mass of the sample after extraction (g).

[0047] Molecular weight determination: The determination was performed using a 2414 gel permeation chromatograph (GPC) produced by Waters, USA. The polystyrene standard was used as the calibration curve, the mobile phase was tetrahydrofuran, the column temperature was 40°C, the sample concentration was 1 mg / ml, the injection volume was 50 μL, the elution time was 40 min, and the flow rate was 1 ml·min -1 .

[0048] Determination of HNBR hydrogenation degree: Using nuclear magnetic resonance hydrogen spectrum ( 1 The degree of hydrogenation of hydrogenated nitrile rubber is calculated by HNMR (HNMR), and the main method is as follows: 1. The product is completely dissolved in deuterated chloroform to prepare a nuclear magnetic resonance hydrogen spectrum sample; 2. After measuring the nuclear magnetic resonance hydrogen spectrum, its spectrum is analyzed: The degree of hydrogenation of hydrogenated nitrile rubber is measured by nuclear magnetic resonance hydrogen spectrum, and is calculated according to the following method: the proton characteristic peak of 1,4-C=C-: 5.4ppm, the proton characteristic peak of 1,2-C=C-: 5.0ppm, the proton characteristic peak of saturated hydrocarbons: 1.25ppm, the proton characteristic peak of cyano-linked: 2.5ppm, and the calculation formula of the degree of hydrogenation is as follows:

[0049] Degree of hydrogenation HD (%) = 1-unsaturation (U)

[0050] Determination of glass transition temperature Tg: DSC is used to measure the glass transition temperature of the product. The instrument model is DSC1, the company is Swiss Mettler, the temperature rise range is -80 to 80°C, and the temperature rise rate is 10°C / min.

[0051] Example 1

[0052] (1) Preparation of reactive macromolecular long-chain grafting agent:

[0053] First, nitrogen was replaced twice in a 10L autoclave, 3000g of xylene was added, and after the temperature was raised to 70°C, 100g of methylaluminoxane co-catalyst was gradually added dropwise under uniform stirring at a speed of 500rpm, and stirring was continued for 15min under the protection of nitrogen gas, and then 10g of trans-bromophenyl (bis (triphenylphosphine)) nickel main catalyst and 200g of 1-octene were added and ethylene was introduced, and the pressure was maintained at 10MPa for 3.0hr; after the reaction was completed, centrifugal separation and drying were performed to obtain a reactive macromolecular long-chain grafting agent (number average molecular weight Mn was 4100).

[0054] (2) Preparation of long-chain branched nitrile rubber:

[0055] First, 200g of nitrile rubber 2707 was dissolved in chlorobenzene solution to prepare a 5% glue solution by mass, and then the glue solution was added to a 10L stainless steel reactor with a jacket, and nitrogen gas was replaced 3 times. Then 10g of reactive macromolecular long-chain grafting agent was added to the reactor, stirred and mixed, and heated. When the temperature of the reactor reached 70°C, a mixed solution of 0.06g DCP and 100g chlorobenzene was added. After reacting for 6.0 hours, it was flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain a long-chain branched nitrile rubber (grafting rate 3.8%).

[0056] (3) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0057] First, 100g of long-chain branched nitrile rubber was dissolved in xylene to prepare a 3% rubber solution by mass, then added to a 10L high-pressure reactor and nitrogen was introduced to remove the air in the reactor. Then, hydrogen was used to remove the nitrogen in the reactor for 30 minutes, and 0.1g of Grubbs II catalyst xylene solution (mass concentration was 5%) was added under nitrogen protection. The hydrogen pressure in the pressurized reactor was 6MPa, and the temperature was raised to 80°C. After reacting for 8.0 hours, the system was cooled, condensed, and vacuum dried to obtain low-temperature resistant hydrogenated nitrile rubber for oil fields. Sampling analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0058] Example 2

[0059] (1) Preparation of reactive macromolecular long-chain grafting agent:

[0060] First, nitrogen was replaced twice in a 10L high-pressure reactor, 3500g of xylene was added, and after the temperature was raised to 75°C, 120g of methylaluminoxane co-catalyst was gradually added dropwise under uniform stirring at a speed of 550rpm, and stirring was continued for 20min under the protection of nitrogen gas, and then 10g of trans-bromophenyl (bis (triphenylphosphine)) nickel main catalyst and 220g of 1-octene were added and ethylene was introduced, and the pressure was maintained at 11MPa for 3.5hr; after the reaction was completed, centrifugal separation and drying were performed to obtain a reactive macromolecular long-chain grafting agent (number average molecular weight Mn was 4600).

[0061] (2) Preparation of long-chain branched nitrile rubber:

[0062] First, 200g of nitrile rubber 2707 was dissolved in chlorobenzene solution to prepare a 5.5% glue solution by mass, and then the glue solution was added to a 10L stainless steel reactor with a jacket, and nitrogen gas was replaced 3 times. Then 11g of reactive macromolecular long-chain grafting agent was added to the reactor, stirred and mixed, and heated. When the temperature of the reactor reached 72°C, a mixture of 0.07g DCP and 120g chlorobenzene was added. After reacting for 6.2 hours, it was flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain a long-chain branched nitrile rubber (grafting rate 4.1%).

[0063] (3) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0064] First, 100g of long-chain branched nitrile rubber was dissolved in xylene to prepare a 5% rubber solution by mass, then added to a 10L high-pressure reactor and nitrogen was introduced to remove the air in the reactor. Then, hydrogen was used to remove the nitrogen in the reactor for 32 minutes, and 0.2g of Grubbs II catalyst xylene solution (mass concentration was 6%) was added under nitrogen protection. The hydrogen pressure in the pressurized reactor was 7MPa, and the temperature was raised to 90°C. After the reaction for 8.5 hours, the system was cooled, condensed, and vacuum dried to obtain low-temperature resistant hydrogenated nitrile rubber for oil fields. Sampling analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0065] Example 3

[0066] (1) Preparation of reactive macromolecular long-chain grafting agent:

[0067] First, nitrogen was replaced twice in a 10L autoclave, 4000g of xylene was added, and the temperature was raised to 80°C. Then, 140g of methylaluminoxane co-catalyst was gradually added dropwise under uniform stirring at a speed of 600rpm, and stirring was continued for 23min under the protection of nitrogen gas. Then, 10g of trans-bromophenyl(bis(triphenylphosphine))nickel main catalyst and 240g of 1-octene were added, and ethylene was introduced, and the pressure was maintained at 12MPa for 4.0hr. After the reaction was completed, centrifugal separation and drying were performed to obtain a reactive macromolecular long-chain grafting agent (number average molecular weight Mn was 5100).

[0068] (2) Preparation of long-chain branched nitrile rubber:

[0069] First, 200g of nitrile rubber 2707 was dissolved in chlorobenzene solution to prepare a 6.0% glue solution by mass, and then the glue solution was added to a 10L stainless steel reactor with a jacket, and nitrogen gas was replaced 4 times. Then 12g of reactive macromolecular long-chain grafting agent was added to the reactor, stirred and mixed, and heated. When the temperature of the reactor reached 74°C, a mixture of 0.08g DCP and 140g chlorobenzene was added. After reacting for 6.4 hours, it was flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain a long-chain branched nitrile rubber (grafting rate 4.3%).

[0070] (3) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0071] First, 100g of long-chain branched nitrile rubber was dissolved in xylene to prepare a 5% rubber solution by mass, then added to a 10L high-pressure reactor and nitrogen was introduced to remove the air in the reactor. Then, hydrogen was used to remove the nitrogen in the reactor for 35 minutes, and 0.3g of Grubbs II catalyst xylene solution (mass concentration was 7%) was added under nitrogen protection. The hydrogen pressure in the pressurized reactor was 8MPa, and the temperature was raised to 95°C. After reacting for 9.0 hours, the system was cooled, condensed, and vacuum dried to obtain low-temperature resistant hydrogenated nitrile rubber for oil fields. Sampling analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0072] Example 4

[0073] (1) Preparation of reactive macromolecular long-chain grafting agent:

[0074] First, nitrogen was replaced twice in a 10L high-pressure reactor, 4300g of xylene was added, and the temperature was raised to 83°C. Then, 160g of methylaluminoxane co-catalyst was gradually added dropwise under uniform stirring at a speed of 620rpm, and stirring was continued for 25min under the protection of nitrogen gas. Then, 10g of trans-bromophenyl (bis(triphenylphosphine)) nickel main catalyst and 260g of 1-octene were added and ethylene was introduced, and the pressure was maintained at 13MPa for 4.4hr. After the reaction was completed, centrifugal separation and drying were performed to obtain a reactive macromolecular long-chain grafting agent (number average molecular weight Mn was 5400).

[0075] (2) Preparation of long-chain branched nitrile rubber:

[0076] First, 200g of nitrile rubber 2707 was dissolved in chlorobenzene solution to prepare a 6.4% glue solution by mass, and then the glue solution was added to a 10L stainless steel reactor with a jacket, and nitrogen gas was replaced 4 times. Then 12.5g of reactive macromolecular long-chain grafting agent was added to the reactor, stirred, mixed, and heated. When the temperature of the reactor reached 76°C, a mixture of 0.085g DCP and 170g chlorobenzene was added. After reacting for 6.6 hours, it was flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain long-chain branched nitrile rubber (grafting rate 4.4%).

[0077] (3) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0078] First, 100g of long-chain branched nitrile rubber was dissolved in xylene to prepare a 6% rubber solution by mass, then added to a 10L high-pressure reactor and nitrogen was introduced to remove the air in the reactor. Then, hydrogen was used to remove the nitrogen in the reactor for 37 minutes, and 0.35g of Grubbs II catalyst xylene solution (mass concentration was 8%) was added under nitrogen protection. The hydrogen pressure in the pressurized reactor was 8.5MPa, and the temperature was raised to 100°C. After reacting for 9.3 hours, the system was cooled, condensed, and vacuum dried to obtain low-temperature resistant hydrogenated nitrile rubber for oil fields. Sampling analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0079] Example 5

[0080] (1) Preparation of reactive macromolecular long-chain grafting agent:

[0081] First, nitrogen was replaced three times in a 10L high-pressure reactor, 4600g of xylene was added, and after the temperature was raised to 87°C, 180g of methylaluminoxane co-catalyst was gradually added dropwise under uniform stirring at a speed of 660rpm, and stirring was continued for 28min under the protection of nitrogen gas, and then 10g of trans-bromphenyl (bis (triphenylphosphine)) nickel main catalyst and 280g of 1-octene were added and ethylene was introduced, and the pressure was maintained at 14MPa for 4.6hr; after the reaction was completed, centrifugal separation and drying were performed to obtain a reactive macromolecular long-chain grafting agent (number average molecular weight Mn was 5600).

[0082] (2) Preparation of long-chain branched nitrile rubber:

[0083] First, 200g of nitrile rubber 2707 was dissolved in chlorobenzene solution to prepare a 6.6% glue solution by mass, and then the glue solution was added to a 10L stainless steel reactor with a jacket, and nitrogen gas was replaced 5 times, and then 13g of reactive macromolecular long-chain grafting agent was added to the reactor, stirred and mixed, and heated. When the temperature of the reactor reached 78°C, a mixture of 0.09g DCP and 180g chlorobenzene was added. After reacting for 6.8 hours, it was flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain a long-chain branched nitrile rubber (grafting rate 4.6%).

[0084] (3) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0085] First, 100g of long-chain branched nitrile rubber was dissolved in xylene to prepare a rubber solution with a mass fraction of 8%, and then added to a 10L high-pressure reactor to pass nitrogen to remove the air in the reactor, and then hydrogen was used to remove the nitrogen in the reactor for 38 minutes, and then 0.4g of Grubbs II catalyst xylene solution (mass concentration of 9%) was added under nitrogen protection, the hydrogen pressure in the pressurized reactor was 9MPa, the temperature was raised to 105°C, and after reacting for 9.6 hours, the system was cooled, condensed, and vacuum dried to obtain low-temperature resistant hydrogenated nitrile rubber for oil fields. Sampling analysis: Standard samples were made, and the tested properties are shown in Table 1.

[0086] Example 6

[0087] (1) Preparation of reactive macromolecular long-chain grafting agent:

[0088] First, nitrogen was replaced three times in a 10L autoclave, 5000g of xylene was added, and the temperature was raised to 90°C. Then, 200g of methylaluminoxane co-catalyst was gradually added dropwise under uniform stirring at a speed of 700rpm, and stirring was continued for 30min under the protection of nitrogen gas. Then, 10g of trans-bromophenyl (bis(triphenylphosphine)) nickel main catalyst and 300g of 1-octene were added, and ethylene was introduced, and the pressure was maintained at 15MPa for 6.0hr. After the reaction was completed, centrifugal separation and drying were performed to obtain a reactive macromolecular long-chain grafting agent (number average molecular weight Mn was 6000).

[0089] (2) Preparation of long-chain branched nitrile rubber:

[0090] First, 200g of nitrile rubber 2707 was dissolved in chlorobenzene solution to prepare a 7.0% glue solution by mass, and then the glue solution was added to a 10L stainless steel reactor with a jacket, and nitrogen gas was replaced 5 times, and then 14g of reactive macromolecular long-chain grafting agent was added to the reactor, stirred and mixed, and heated. When the temperature of the reactor reached 80°C, a mixed solution of 0.1g DCP and 200g chlorobenzene was added. After reacting for 7.0 hours, it was flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain a long-chain branched nitrile rubber (grafting rate 4.9%).

[0091] (3) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0092] First, 100g of long-chain branched nitrile rubber was dissolved in xylene to prepare a 10% rubber solution by mass, and then added to a 10L high-pressure reactor to pass nitrogen to remove the air in the reactor, and then hydrogen was used to remove the nitrogen in the reactor for 40 minutes, and then 0.5g of Grubbs II catalyst xylene solution (mass concentration of 10%) was added under nitrogen protection, the hydrogen pressure in the pressurized reactor was 10MPa, the temperature was raised to 110°C, and after reacting for 10.0hr, the system was cooled, condensed, and vacuum dried to obtain low-temperature resistant hydrogenated nitrile rubber for oil fields. Sampling analysis: Standard samples were made, and the tested properties are shown in Table 1.

[0093] Example 7

[0094] (1) Preparation of reactive macromolecular long-chain grafting agent:

[0095] First, nitrogen was replaced three times in a 10L high-pressure reactor, 5000g of xylene was added, and the temperature was raised to 90°C. Then, 200g of ethylaluminoxane co-catalyst was gradually added dropwise under uniform stirring at a speed of 700rpm, and stirring was continued for 30min under the protection of nitrogen gas. Then, 10g of 2,5-diformylpyrrole nickel dibromide main catalyst and 300g of 1-hexene were added, and ethylene was introduced, and the pressure was maintained at 15MPa for 6.0hr. After the reaction was completed, centrifugal separation and drying were performed to obtain a reactive macromolecular long-chain grafting agent (number average molecular weight Mn was 5700).

[0096] (2) Preparation of long-chain branched nitrile rubber:

[0097] First, 200g of nitrile rubber 2707 was dissolved in chlorobenzene solution to prepare a 7.0% glue solution by mass, and then the glue solution was added to a 10L stainless steel reactor with a jacket, and nitrogen gas was replaced 5 times. Then 14g of reactive macromolecular long-chain grafting agent was added to the reactor, stirred, mixed, and heated. When the temperature of the reactor reached 80°C, a mixture of 0.2g of diacetyl peroxide and 200g of chlorobenzene was added. After reacting for 7.0 hours, it was flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain a long-chain branched nitrile rubber (grafting rate 4.7%).

[0098] (3) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0099] First, 100g of long-chain branched nitrile rubber was dissolved in xylene to prepare a 10% rubber solution by mass, and then added to a 10L high-pressure reactor to pass nitrogen to remove the air in the reactor, and then hydrogen was used to remove the nitrogen in the reactor for 40 minutes, and then 0.5g of Grubbs II catalyst xylene solution (mass concentration of 10%) was added under nitrogen protection, the hydrogen pressure in the pressurized reactor was 10MPa, the temperature was raised to 110°C, and after reacting for 10.0hr, the system was cooled, condensed, and vacuum dried to obtain low-temperature resistant hydrogenated nitrile rubber for oil fields. Sampling analysis: Standard samples were made, and the tested properties are shown in Table 1.

[0100] Comparative Example 1

[0101] (1) Preparation of reactive macromolecular long-chain grafting agent:

[0102] The other conditions are the same as those in Example 1, except that the amount of trans-bromophenyl (bis(triphenylphosphine)) nickel main catalyst added during the preparation of the reactive macromolecular long chain grafting agent is 5 g, that is: first, nitrogen is passed through a 10L high pressure reactor for replacement twice, 3000 g of xylene is added, and the temperature is raised to 70°C. Then, 100 g of methylaluminoxane co-catalyst is gradually added dropwise under uniform stirring at a speed of 500 rpm, and stirring is continued for 15 min under nitrogen gas protection, and then 5 g of trans-bromophenyl (bis(triphenylphosphine)) nickel main catalyst and 200 g of 1-octene are added and ethylene is passed, and the pressure is maintained at 10 MPa for reaction for 3.0 hr; after the reaction is completed, centrifugation and drying are performed to obtain a reactive macromolecular long chain grafting agent a (number average molecular weight Mn is 2600).

[0103] (2) Preparation of long-chain branched nitrile rubber:

[0104] The other conditions are the same as those in Example 1, except that in the preparation process of the long-chain branched nitrile rubber, no reactive macromolecular long-chain grafting agent is added, but a reactive macromolecular long-chain grafting agent a is added in an amount of 10 g, that is, first, 200 g of nitrile rubber 2707 is dissolved in a chlorobenzene solution to prepare a 5% glue solution by mass, and then the glue solution is added to a 10L stainless steel reactor with a jacket, and nitrogen gas is passed through it for replacement 3 times, and then 10 g of reactive macromolecular long-chain grafting agent a is added to the reactor, stirred and mixed, and heated. When the reactor temperature reaches 70°C, a mixed solution of 0.06 g of DCP and 100 g of chlorobenzene is added, and after reacting for 6.0 hours, it is flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain a long-chain branched nitrile rubber a (grafting rate 3.5%).

[0105] (3) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0106] Other conditions are the same as in Example 1, except that in the preparation process of the low temperature resistant hydrogenated nitrile rubber for oil field, long-chain branched nitrile rubber is not added, but long-chain branched nitrile rubber a is added, and its addition amount is 100g, that is: first 100g long-chain branched nitrile rubber a is dissolved in xylene, configured to be 3% glue solution by mass fraction, then added into 10L autoclave to pass nitrogen to remove the air in the reactor, then after 30min of nitrogen removal in the reactor with hydrogen, 0.1g xylene solution of Grubbs II catalyst (mass concentration is 5%) is added under nitrogen protection, the hydrogen pressure in the supercharged reactor is 6MPa, warming up to 80 ℃, after reacting 8.0hr, the system cools down, condenses, and vacuum drying obtains the low temperature resistant hydrogenated nitrile rubber for oil field. Sampling analysis: standard sample is made, and the tested performance is shown in Table 1.

[0107] Comparative Example 2

[0108] (1) Preparation of reactive macromolecular long-chain grafting agent:

[0109] The other conditions are the same as those in Example 2, except that 1-octene is not added during the preparation of the reactive macromolecular long chain grafting agent, but 1-butene is added in an amount of 220 g, that is: first, nitrogen is passed through a 10L high pressure reactor for replacement twice, 3500 g of xylene is added, and after the temperature is raised to 75°C, 120 g of methylaluminoxane co-catalyst is gradually added dropwise under uniform stirring at a speed of 550 rpm, and stirring is continued for 20 min under nitrogen gas protection, and then 10 g of trans-bromphenyl (bis (triphenylphosphine)) nickel main catalyst and 220 g of 1-butene are added and ethylene is passed, and the pressure is maintained at 11 MPa for reaction for 3.5 hr; after the reaction is completed, centrifugation and drying are performed to obtain a reactive macromolecular long chain grafting agent b (number average molecular weight Mn is 3900).

[0110] (2) Preparation of long-chain branched nitrile rubber:

[0111] The other conditions are the same as those in Example 2, except that in the preparation process of the long-chain branched nitrile rubber, no reactive macromolecular long-chain grafting agent is added, but a reactive macromolecular long-chain grafting agent b is added in an amount of 11 g, that is, first, 200 g of nitrile rubber 2707 is dissolved in a chlorobenzene solution to form a glue solution with a mass fraction of 5.5%, and then the glue solution is added to a 10L stainless steel reactor with a jacket, and nitrogen gas is passed through it for replacement 3 times, and then 11 g of reactive macromolecular long-chain grafting agent b is added to the reactor, stirred and mixed, and heated. When the reactor temperature reaches 72°C, a mixed solution of 0.07 g of DCP and 120 g of chlorobenzene is added, and after reacting for 6.2 hours, it is flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain a long-chain branched nitrile rubber b (grafting rate 4.2%).

[0112] (3) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0113] Other conditions are the same as in Example 2, except that in the preparation process of the low temperature resistant hydrogenated nitrile rubber for oil field, long-chain branched nitrile rubber b is not added, but long-chain branched nitrile rubber b is added, and its addition amount is 100g, that is: first 100g long-chain branched nitrile rubber b is dissolved in dimethylbenzene, and it is 5% glue liquid configured to mass fraction, and then joins in 10L autoclave and passes nitrogen to remove the air in the reactor, and then removes the nitrogen in the reactor with hydrogen for 32min, and then adds the dimethylbenzene solution (mass concentration is 6%) of 0.2g Grubbs II catalyst under nitrogen protection, and the hydrogen pressure in the supercharged reactor is 7MPa, is warming up to 90 ℃, reacts after 8.5hr, and the system cools down, condenses, and vacuum drying obtains the low temperature resistant hydrogenated nitrile rubber for oil field. Sampling analysis: make standard sample, and the tested performance is shown in Table 1.

[0114] Comparative Example 3

[0115] (1) Preparation of reactive macromolecular long-chain grafting agent:

[0116] The other conditions were the same as those in Example 3, except that ethylene was introduced during the preparation of the reactive macromolecular long chain grafting agent, and the pressure was maintained at 4 MPa instead of 12 MPa, namely: first, nitrogen was passed through a 10L autoclave for replacement twice, 4000g of xylene was added, and the temperature was raised to 80°C. Then, 140g of methylaluminoxane co-catalyst was gradually added dropwise under uniform stirring at a speed of 600rpm, and stirring was continued for 23min under nitrogen gas protection, and then 10g of trans-bromphenyl (bis(triphenylphosphine)) nickel main catalyst and 240g of 1-octene were added and ethylene was introduced, and the pressure was maintained at 4MPa for reaction for 4.0hr; after the reaction was completed, the reactive macromolecular long chain grafting agent c (number average molecular weight Mn was 4900) was obtained by centrifugation and drying.

[0117] (2) Preparation of long-chain branched nitrile rubber:

[0118] The other conditions are the same as those in Example 3, except that in the preparation process of the long-chain branched nitrile rubber, no reactive macromolecular long-chain grafting agent is added, but a reactive macromolecular long-chain grafting agent c is added in an amount of 12 g, that is, first, 200 g of nitrile rubber 2707 is dissolved in a chlorobenzene solution to prepare a glue solution with a mass fraction of 6.0%, and then the glue solution is added to a 10L stainless steel reactor with a jacket, and nitrogen gas is passed through it for replacement 4 times, and then 12 g of reactive macromolecular long-chain grafting agent c is added to the reactor, stirred and mixed, and heated. When the reactor temperature reaches 74°C, a mixed solution of 0.08 g of DCP and 140 g of chlorobenzene is added, and after reacting for 6.4 hours, it is flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain a long-chain branched nitrile rubber c (grafting rate 1.2%).

[0119] (3) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0120] Other conditions are the same as in Example 3, except that in the preparation process of the low temperature resistant hydrogenated nitrile rubber for oil field, long-chain branched nitrile rubber c is not added, but long-chain branched nitrile rubber c is added, and its addition amount is 100g, that is: first 100g long-chain branched nitrile rubber c is dissolved in dimethylbenzene, configured to be 5% glue solution by mass fraction, then join in 10L autoclave and pass nitrogen to remove the air in the reactor, then remove the nitrogen in the reactor with hydrogen for 35min, add 0.3g Grubbs II catalyst dimethylbenzene solution (mass concentration is 7%) under nitrogen protection, the hydrogen pressure in the supercharged reactor is 8MPa, be warming up to 95 ℃, react after 9.0hr, system cooling, condensation, vacuum drying obtains the low temperature resistant hydrogenated nitrile rubber for oil field. Sampling analysis: make standard sample, and the tested performance is shown in Table 1.

[0121] Comparative Example 4

[0122] (1) Preparation of reactive macromolecular long chain grafting agent: same as Example 4.

[0123] (2) Preparation of long-chain branched nitrile rubber:

[0124] The other conditions are the same as those in Example 4, except that the amount of the reactive macromolecular long chain grafting agent added during the preparation of the long-chain branched nitrile rubber is 6.0 g, that is, first, 200 g of nitrile rubber 2707 is dissolved in a chlorobenzene solution to prepare a 6.4% glue solution by mass, and then the glue solution is added to a 10L stainless steel reactor with a jacket, and the nitrogen gas is replaced 4 times, and then 6.0 g of the reactive macromolecular long chain grafting agent is added to the reactor, stirred and mixed, and heated. When the reactor temperature reaches 76°C, a mixed solution of 0.085 g of DCP and 170 g of chlorobenzene is added, and after reacting for 6.6 hours, it is flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain a long-chain branched nitrile rubber d (grafting rate 2.7%).

[0125] (3) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0126] Other conditions are the same as in Example 4, except that in the preparation process of the low temperature resistant hydrogenated nitrile rubber for oil field, long-chain branched nitrile rubber d is not added, but long-chain branched nitrile rubber d is added, and its addition amount is 100g, that is: first 100g long-chain branched nitrile rubber d is dissolved in xylene, configured to be 6% glue solution by mass fraction, then join in 10L autoclave and pass nitrogen to remove the air in the reactor, then remove the nitrogen in the reactor with hydrogen for 37min, add 0.35g Grubbs II catalyst xylene solution (mass concentration is 8%) under nitrogen protection, the hydrogen pressure in the supercharged reactor is 8.5MPa, be warming up to 100 ℃, react after 9.3hr, system cooling, condensation, vacuum drying obtains the low temperature resistant hydrogenated nitrile rubber for oil field. Sampling analysis: make standard sample, and the tested performance is shown in Table 1.

[0127] Comparative Example 5

[0128] (1) Preparation of long-chain branched nitrile rubber:

[0129] The other conditions are the same as those in Example 5, except that in the preparation process of the long-chain branched nitrile rubber, no reactive macromolecular long-chain grafting agent is added, but a small molecular monomer 1-octene is added in an amount of 13 g, that is, first, 200 g of nitrile rubber 2707 is dissolved in a chlorobenzene solution to prepare a glue solution with a mass fraction of 6.6%, and then the glue solution is added to a 10L stainless steel reactor with a jacket, and nitrogen gas is passed through it for replacement 5 times, and then 13 g of 1-octene is added to the reactor, stirred and mixed, and heated. When the reactor temperature reaches 78°C, a mixed solution of 0.09 g of DCP and 180 g of chlorobenzene is added, and after reacting for 6.8 hours, it is flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain a long-chain branched nitrile rubber e (grafting rate 4.8%).

[0130] (2) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0131] Other conditions are the same as in Example 5, except that in the preparation process of the low temperature resistant hydrogenated nitrile rubber for oil field, long-chain branched nitrile rubber e is not added, but long-chain branched nitrile rubber e is added, and its addition amount is 100g, that is: first 100g long-chain branched nitrile rubber e is dissolved in xylene, configured to be 8% glue solution by mass, then added into 10L autoclave to pass nitrogen to remove the air in the reactor, then after 38min of nitrogen removal in the reactor with hydrogen, 0.4g xylene solution of Grubbs II catalyst (mass concentration is 9%) is added under nitrogen protection, the hydrogen pressure in the supercharged reactor is 9MPa, warming up to 105 ℃, after reacting 9.6hr, the system cools down, condenses, and vacuum drying obtains the low temperature resistant hydrogenated nitrile rubber for oil field. Sampling analysis: standard sample is made, and the tested performance is shown in Table 1.

[0132] Comparative Example 6

[0133] (1) Preparation of reactive macromolecular long chain grafting agent: same as Example 6.

[0134] (2) Preparation of long-chain branched nitrile rubber:

[0135] The other conditions are the same as those in Example 6, except that the amount of DCP added during the preparation of the long-chain branched nitrile rubber is 0.01 g, that is, first, 200 g of nitrile rubber 2707 is dissolved in a chlorobenzene solution to form a 7.0% glue solution by mass, and then the glue solution is added to a 10L stainless steel reactor with a jacket, and the nitrogen gas is replaced 5 times, and then 14 g of a reactive macromolecular long-chain grafting agent is added to the reactor, stirred and mixed, and heated. When the reactor temperature reaches 80°C, a mixed solution of 0.01 g of DCP and 200 g of chlorobenzene is added, and after reacting for 7.0 hours, it is flocculated with anhydrous ethanol, washed, and dried in a 70°C oven to constant weight to obtain a long-chain branched nitrile rubber f (grafting rate 3.2%).

[0136] (3) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0137] Other conditions are the same as in Example 6, except that in the preparation process of the low temperature resistant hydrogenated nitrile rubber for oil field, long-chain branched nitrile rubber f is not added, and the addition amount is 100g, that is: first 100g long-chain branched nitrile rubber f is dissolved in xylene, configured to a glue solution with a mass fraction of 10%, then added to a 10L autoclave to pass nitrogen to remove the air in the reactor, then after the nitrogen in the reactor is removed by hydrogen for 40min, 0.5g Grubbs II catalyst xylene solution (mass concentration is 10%) is added under nitrogen protection, the hydrogen pressure in the supercharged reactor is 10MPa, warming up to 110°C, after reacting for 10.0hr, the system is cooled, condensed, and vacuum dried to obtain the low temperature resistant hydrogenated nitrile rubber for oil field. Sampling analysis: standard specimens are made, and the tested performance is shown in Table 1.

[0138] Comparative Example 7

[0139] (1) Preparation of long-chain branched nitrile rubber:

[0140] The other conditions are the same as those in Example 7, except that the reactive macromolecular long chain grafting agent is not added during the preparation of the long-chain branched nitrile rubber, but a small molecule monomer 1-hexene is added in an amount of 14 g, namely: first, 200 g of nitrile rubber 2707 is dissolved in a chlorobenzene solution to form a 7.0% glue solution by mass, and then the glue solution is added to a 10L stainless steel reactor with a jacket, and the nitrogen gas is replaced 5 times, and then 14 g of 1-hexene is added to the reactor, stirred and mixed, heated, and a mixture of 0.2 g of diacetyl peroxide and 200 g of chlorobenzene is added when the reactor temperature reaches 80 ° C. After the reaction, flocculation with anhydrous ethanol, washing, and drying in a 70 ° C oven to constant weight to obtain a long-chain branched nitrile rubber g (grafting rate 5.0%).

[0141] (2) Preparation of low temperature resistant hydrogenated nitrile rubber for oil fields:

[0142] Other conditions are the same as in Example 7, except that in the preparation process of the low temperature resistant hydrogenated nitrile rubber for oil field, long-chain branched nitrile rubber g is not added, but long-chain branched nitrile rubber g is added, and its addition amount is 100g, that is: first 100g long-chain branched nitrile rubber g is dissolved in xylene, configured to be 10% glue solution by mass fraction, then added into 10L autoclave to pass nitrogen to remove the air in the reactor, then after 40min of nitrogen removal in the reactor with hydrogen, 0.5g xylene solution of Grubbs II catalyst (mass concentration is 10%) is added under nitrogen protection, the hydrogen pressure in the supercharged reactor is 10MPa, warming up to 110 ℃, after reacting 10.0hr, the system cools down, condenses, and vacuum drying obtains the low temperature resistant hydrogenated nitrile rubber for oil field. Sampling analysis: standard sample is made, and the tested performance is shown in Table 1.

[0143] Table 1 Properties of low temperature resistant hydrogenated nitrile rubber for oil field

[0144]

[0145] It can be seen from Table 1 that the low-temperature resistant hydrogenated nitrile rubber for oil fields of the present invention has a low glass transition temperature and is suitable for oil well operations under low-temperature conditions of -49°C.

[0146] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing low-temperature resistant hydrogenated nitrile rubber for oil fields, characterized in that: The steps include: (1) firstly, introducing an inert gas into a reaction kettle for replacement, adding a solvent, raising the temperature, adding an alkylaluminoxane co-catalyst under stirring, continuing stirring under the protection of the inert gas, then adding a nickel-based complex catalyst and a long-chain α-olefin and introducing ethylene to start the reaction; after the reaction is completed, centrifugation and drying are performed to obtain a reactive macromolecular long-chain grafting agent; (2) dissolving the nitrile rubber in a chlorobenzene solution to prepare a glue solution, then adding the glue solution into a reactor, introducing nitrogen for replacement, then adding a reactive macromolecular long-chain grafting agent into the reactor, stirring and mixing, heating, then adding a mixed solution of an initiator and chlorobenzene, reacting, and after the reaction is completed, flocculating, washing, and drying to obtain a long-chain branched nitrile rubber; (3) dissolving the long-chain branched nitrile rubber in a solvent to prepare a rubber solution, then adding the solution into a reactor to remove the air in the reactor by introducing an inert gas, then removing the inert gas in the reactor by using hydrogen, adding a xylene solution of a Grubbs II catalyst under nitrogen protection, pressurizing and heating, reacting, cooling, condensing, and drying to obtain a low-temperature resistant hydrogenated nitrile rubber for oil fields; The reactive macromolecular long chain grafting agent has the following structure: Among them, R is C6~C 12 m and n are the number of repeating units, n≥1, and m≥1; the number average molecular weight (Mn) of the reactive macromolecular long-chain grafting agent is 4000-6000.

2. The preparation method according to claim 1, characterized in that: The long-chain α-olefin is selected from one of 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene and 1-dodecene.

3. The preparation method according to claim 1, characterized in that: The nickel-based complex catalyst is selected from one of (1-naphthyl)〔8-(diphenylphosphino)quinoline〕nickel chloride, trans-phenyl(bis(triphenylphosphine))nickel bromide and 2,5-diformylpyrrole nickel dibromide.

4. The preparation method according to claim 1, characterized in that: The alkylaluminoxane cocatalyst is selected from one of methylaluminoxane (MAO) and ethylaluminoxane (EAO).

5. The preparation method according to claim 1, characterized in that: In step (1), the mass ratio of the solvent, the alkylaluminoxane co-catalyst, the long-chain α-olefin and the nickel-based complex catalyst is 300-500:10-20:20-30:

1.

6. The preparation method according to claim 1, characterized in that: The initiator is selected from one of diacetyl peroxide, diisobutyryl peroxide, cumene hydroperoxide, dicumyl peroxide (DCP) and dibenzoyl peroxide, and its addition amount is 0.01-0.1 part based on 100 parts of the mass of the nitrile rubber.

7. The preparation method according to claim 1, characterized in that: The nitrile rubber is copolymerized by emulsion polymerization of 1,3-butadiene and acrylonitrile, wherein the acrylonitrile content of the nitrile rubber is 20wt% to 42wt%.

8. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of the reactive macromolecular long chain grafting agent, chlorobenzene and nitrile rubber is 5 to 7:50 to 100:

100.

9. The preparation method according to claim 1, characterized in that: In step (2), the grafting rate of the long-chain branched nitrile rubber is 3.8% to 4.9%.

10. The preparation method according to claim 1, characterized in that: The solvent is selected from one of cyclohexane, carbon disulfide (CS2), nitrobenzene, petroleum ether, tetrachloroethane, toluene and xylene.

11. The preparation method according to claim 1, characterized in that: In step (3), the mass ratio of the long-chain branched nitrile rubber to the Grubbs II catalyst is 100:0.1-0.

5.

12. A low-temperature resistant hydrogenated nitrile rubber for oil field obtained by the preparation method according to any one of claims 1 to 11.

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