Low-temperature-resistant wear-resistant ester-containing nitrile rubber and preparation method thereof

Abstract

The preparation method comprises the following steps: adding water, an emulsifier, an activation phase, a phenyl acrylate-containing monomer, acrylonitrile and a molecular weight regulator into a polymerization kettle, vacuumizing, carrying out nitrogen replacement for several times, adding a deoxidant and a butadiene monomer, adding an initiator, carrying out heat preservation for several times, and carrying out heat preservation for several times, so as to obtain the low-temperature-resistant wear-resistant ester-containing nitrile rubber. Starting polymerization reaction; when the conversion rate reaches 25%-30%, supplementing a phenyl acrylate-containing monomer, and when the polymerization conversion rate reaches 45%-50%, supplementing acrylonitrile, an initiator and a molecular weight regulator; when the polymerization conversion rate reaches 60%-65%, supplementing the phenyl acrylate-containing monomer; and continuing the reaction until the polymerization conversion rate reaches 80-85%, adding a terminator, continuing the stirring reaction, discharging, and condensing, washing and drying the latex obtained by the reaction to obtain the low-temperature-resistant wear-resistant ester-containing nitrile rubber. The ester-containing nitrile rubber prepared by the preparation method has excellent properties such as low temperature resistance and wear resistance.

Description

Technical Field

[0001] The invention relates to the field of preparation of nitrile rubber, in particular to a method for preparing oil-resistant and low-temperature-resistant ester-containing nitrile rubber by introducing a third monomer. Background Art

[0002] With the rapid development of industries such as machinery, aerospace, weapons, ships, and petrochemicals, the demand for sealing materials has grown rapidly, with an annual growth rate of more than 20%. Harsh working conditions such as high altitude, deep sea, full territory, and complex climates have increasingly stringent requirements on the performance of sealing materials such as medium resistance, low temperature resistance, heat resistance, flex resistance, and stability of multiple deformations.

[0003] As a copolymer formed by low-temperature emulsion polymerization of butadiene and acrylonitrile monomers, nitrile rubber is widely used in sealing products because of its good oil resistance, solvent resistance and processing properties. However, the rapid development of technology has made the service conditions of sealing materials increasingly stringent, thus putting forward higher requirements on the performance of nitrile rubber. However, at present, high-performance nitrile rubber products that take into account oil resistance in a wide temperature range, stability of multiple deformations and wear resistance for continuous operation are mostly monopolized by foreign companies. Existing research on the modification of high-performance nitrile rubber is mainly through mixing with high-performance rubbers or introducing third functional monomers for copolymerization, and some results have been achieved, such as carboxyl nitrile rubber, fluorine-containing nitrile rubber and ester-containing nitrile.

[0004] Among them, ester-containing nitrile rubber has attracted the attention of many researchers for its excellent performance. However, the ester monomers used in the current research on ester-containing nitrile rubber are mostly acrylates prepared by dehydration of acrylic acid and fatty alcohols, and ester monomers containing diester functional groups prepared by dehydration of positive and negative olefin diacids and fatty alcohols. The types of ester-containing monomers are relatively single, and the introduction of such ester-containing monomers will directly affect the flexibility of the nitrile rubber molecular chain, making it have excellent low-temperature resistance and stability of multiple deformations, but at the same time it will also reduce the wear resistance of nitrile rubber, resulting in difficulty in processing its sealing products and a large amount of additives, making it difficult to control production costs and improve production efficiency. Therefore, it is urgent to develop an ester-containing nitrile rubber with balanced low-temperature resistance and wear resistance.

[0005] Patent CN113943449A discloses a cold-resistant nitrile rubber sealing material, which is prepared by mixing carboxyl nitrile rubber with polyorganosiloxane and then melt grafting to obtain modified nitrile rubber, which is then blended with butadiene rubber to improve the cold resistance of the material. This can easily lead to uneven dispersion of fillers and rubber, and even more so, it is impossible to achieve uniform dispersion at the molecular level, resulting in poor processing performance and unstable physical and mechanical properties.

[0006] Patent CN104628955A discloses a chemically modified nitrile rubber, which is obtained by terpolymerizing butyl acrylate with butadiene and acrylonitrile, adding sodium oleate, tert-dodecyl mercaptan, sodium pyrophosphate, oleic acid, sodium sulfite, sodium hydroxide, terminator and antioxidant D, etc., and polymerizing at 35°C to 45°C. The obtained latex is subjected to post-treatment such as degassing, coagulation drying, etc. to obtain a modified ester-containing nitrile rubber. However, this method is a high-temperature emulsion polymerization, and the Mooney viscosity of the rubber is high, which is not conducive to processing. Secondly, the raw materials and additives are added at one time, and the content and distribution of nitrile and ester groups in the molecular chain are difficult to accurately control, and the content of the combined ester structure is not specified. Moreover, due to the high polymerization temperature, the Mooney viscosity of the obtained nitrile rubber ML 1+4 100℃ It is 105-145, which is not conducive to processing.

[0007] Patent CN105294939A discloses a low-temperature hydrogenated nitrile rubber raw rubber and its preparation method, firstly, the ester-containing nitrile rubber is prepared by emulsion polymerization: butadiene, acrylonitrile, dibutyl fumarate, deionized water, emulsifier, electrolyte, chelating agent, activator, regulator are added, after stirring and pre-emulsification, deoxidizer and initiator are added, reacted at 4-10°C for 4-15 hours, and latex is prepared, and then the diester-containing nitrile rubber is obtained by demulsification and drying. However, this method is a one-time feeding method, which is not conducive to the uniform distribution and performance regulation of nitrile and ester groups in the polymer, and the technology mainly involves the hydrogenation of ester-containing nitrile rubber and the performance after hydrogenation, and does not involve the performance of unhydrogenated nitrile rubber, and only its molecular weight and distribution are measured.

[0008] Patent CN102731863A discloses a modified nitrile rubber material modified by modified acrylate. The modified acrylate is first prepared by high-temperature solution polymerization: butyl acetate is first added to the reactor, nitrogen is filled for protection, and then versatate, styrene, acrylate, sodium allyloxyhydroxypropyl sulfonate, polyvinyl alcohol, acrylic acid, and isododecyl mercaptan are added. The mixture is stirred and heated to 130°C, sodium persulfate is added to react for 3 hours, and the modified acrylate is obtained by filtering after cooling. Then, nitrile rubber 3345, nitrile rubber 3365, antioxidant RD, antioxidant DNP, stearic acid, sulfur powder, microcrystalline wax, zinc oxide, magnesium oxide, processing aid WB212, modified acrylate, and plasticizer are put into an internal mixer and mixed completely by weight at 73°C, and then the obtained rubber, carbon black N550, carbon black N330, chalk, and epoxy stearate are put into an open mixer and mixed completely by weight at 85°C, and then accelerator M, accelerator TETD, and accelerator DM are added and mixed completely by weight at 93°C, and then processed and formed to prepare modified nitrile rubber. The essence of this method is to improve the compression permanent deformation performance and hardness of nitrile rubber by synthesizing a modified additive containing a benzene ring and other structures, and then by mixing and processing, but not introducing a benzene ring structure into the molecular chain, and does not involve the structural analysis of the modified acrylate, and its performance may be affected by both the modified additive and the mixing process.

[0009] Patent CN110684252A discloses a carboxylated nitrile rubber and a preparation method thereof, with carboxylated nitrile rubber raw rubber, reinforcing agent, antioxidant, esterification vulcanizing agent, esterification dehydrating agent, and esterification accelerator. The preparation method of carboxylated nitrile rubber mainly uses polyol to vulcanize carboxylated nitrile rubber raw rubber, and the alcohol group of the polyol reacts with the carboxyl group of the carboxylated nitrile rubber raw rubber to form an ester bond, and finally forms a cross-linking system through the ester bond to complete the vulcanization of the carboxylated nitrile rubber raw rubber. The method is to form an ester bond through a vulcanization stage reaction, and then form a cross-linking system, and the content distribution of its ester bond is greatly affected by the raw materials and the vulcanization operation.

[0010] Patent CN105837754A discloses a method for preparing carboxylated nitrile rubber, comprising the following steps: in a polymerization kettle, based on 100 parts by weight of total monomers, adding water, emulsifier, activator, 27-33 parts of acrylonitrile, 0.5-5 parts of unsaturated carboxylic acid, 0.2-2.0 parts of molecular weight regulator, after vacuuming and nitrogen replacement, adding deoxidizer and 62-72.5 parts of butadiene, and then adding 0.02-0.25 parts of initiator for polymerization, when the polymerization conversion rate reaches 40%-75%, each of acrylonitrile, initiator and molecular weight regulator are added once, when the conversion rate reaches 80%-84%, a terminator is added to cool and discharge, and carboxylated nitrile latex is prepared, and after coagulation, washing and drying, a carboxylated nitrile rubber product is prepared. However, this method adopts a one-time addition of unsaturated carboxylic acid monomer, which may cause uneven distribution of unsaturated carboxylic acid segments and affect the performance of the polymer.

[0011] Patent CN105026489A discloses a (meth)acrylate resin composition, comprising 71 to 99 wt% of a poly((meth)acrylate alkyl ester-(meth)acrylate phenyl ester) copolymer and 1 to 29 wt% of a conjugated diene polymer. The (meth)acrylate resin composition contains a very high poly((meth)acrylate alkyl ester-(meth)acrylate phenyl ester) copolymer as a base resin, and is prepared by copolymerization such as bulk polymerization, suspension polymerization or solution polymerization, aiming to control the refractive index while maintaining the surface hardness of the material, but does not involve research on the relevant properties of emulsion polymerized nitrile rubber.

[0012] "Preparation and Properties of Butadiene-Acrylonitrile-Butyl Acrylate Terpolymer". In the synthetic rubber industry, butadiene-acrylonitrile-butyl acrylate terpolymer was prepared by emulsion polymerization. Deionized water, acrylonitrile, butyl acrylate, dodecylbenzenesulfonic acid, potassium oleate, tert-dodecyl mercaptan, ferrous sulfate heptahydrate, disodium ethylenediaminetetraacetate, sodium formaldehyde sulfite, and anhydrous sodium carbonate were added to the polymerization kettle, and vacuumed and replaced with nitrogen three times. Butadiene was added and stirred, and the temperature was lowered to 5.0-5.5°C. The initiator was added to start the polymerization reaction. After the reaction started, part of the auxiliary agent was added during the reaction as needed. After the conversion rate reached the index requirement, the terminator was added to terminate the reaction, the temperature was lowered, and the material was discharged to obtain ester-containing nitrile latex. The latex was degassed and an antioxidant was added to mix evenly. After condensation, washing, and drying, ester-containing nitrile rubber was obtained. However, although this method involves the preparation and characterization of ester-containing nitrile rubber, only auxiliary agents are added during the polymerization process, and no monomer is added, and the content of the combined ester structure is not indicated.

[0013] At present, the ester-containing monomers used in the relevant research on ester-containing nitrile rubber have inevitably reduced its wear resistance while improving the low-temperature resistance of nitrile rubber, which directly affects the service life of the sealing components. Summary of the invention

[0014] The purpose of the present invention is to provide a practical preparation method of low-temperature-resistant and wear-resistant ester-containing nitrile rubber, which uses acrylic acid ester containing a benzene ring structure as an ester-containing monomer, adopts low-temperature copolymerization, and introduces ester groups and benzene rings into the nitrile rubber molecular chain by improving the feeding method, raw material ratio, multi-point addition and the like, so that the nitrile rubber has both a cold-resistant structure and a rigid structure, fundamentally changes the structure of the nitrile rubber, significantly improves the performance, and obtains a low-temperature-resistant and wear-resistant ester-containing nitrile rubber.

[0015] To achieve the above object, the present invention provides a method for preparing a low-temperature-resistant and wear-resistant ester-containing nitrile rubber, the preparation method comprising the following steps:

[0016] In a polymerization kettle, water, emulsifier, activating phase, phenyl-containing acrylate monomer, acrylonitrile and molecular weight regulator are added, and after vacuuming and nitrogen replacement for several times, deoxidizer and butadiene monomer are added, and initiator is added to start polymerization reaction; when the conversion rate reaches 25% to 30%, phenyl-containing acrylate monomer is added, and when the polymerization conversion rate reaches 45% to 50%, acrylonitrile, initiator and molecular weight regulator are added; when the polymerization conversion rate reaches 60% to 65%, phenyl-containing acrylate monomer is added; the reaction is continued until the polymerization conversion rate reaches 80% to 85%, a terminator is added, the reaction is continued with stirring, and the material is discharged. After the latex obtained by the reaction is condensed, washed and dried, a low-temperature-resistant and wear-resistant ester-containing nitrile rubber is obtained.

[0017] The method for preparing the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention comprises the following steps: the phenyl-containing acrylate monomer is selected from at least one of benzyl acrylate, phenylethyl acrylate, phenoxyethyl acrylate and 4-ethylphenyl acrylate; before starting the polymerization reaction, the phenyl-containing acrylate monomer is added in an amount of 3.0 to 25.0 parts, preferably 5.0 to 25.0 parts, based on 100 parts of the total weight of the monomers.

[0018] In the method for preparing the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention, before starting the polymerization reaction, the amount of acrylonitrile added is preferably 13.0 to 25.0 parts by weight based on 100 parts by total weight of the monomers.

[0019] In the method for preparing the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention, before starting the polymerization reaction, the amount of the molecular weight regulator added is preferably 0.2 to 0.7 parts based on 100 parts of the total weight of the monomers.

[0020] In the method for preparing the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention, when the polymerization conversion rate reaches 25% to 30%, based on 100 parts of the total weight of the monomers, the weight of the added phenyl-containing acrylate monomer is preferably 1 to 2 parts.

[0021] The method for preparing the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention comprises the following steps: when the polymerization conversion rate reaches 45% to 50%, based on 100 parts of the total weight of the monomers, the weight of the acrylonitrile added is 1 to 4 parts, the weight of the initiator added is 0.002 to 0.006 parts, and the weight of the molecular weight regulator added is 0.03 to 0.06 parts.

[0022] In the method for preparing the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention, when the polymerization conversion rate reaches 60% to 65%, the weight of the added phenyl-containing acrylate monomer is preferably 1 to 4 parts based on 100 parts of the total weight of the monomers.

[0023] The preparation method of the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention comprises the following steps: the emulsifier is an anionic compound emulsifier, which is a compound of sodium dodecylbenzene sulfonate and disproportionated rosin potassium soap, and the compounding ratio is 3-4:1. The amount of the emulsifier added is preferably 4.0-8.0 parts by weight based on 100 parts by total weight of the monomers.

[0024] The method for preparing the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention comprises the following steps: the activating phase is at least one of diatomaceous earth, EDTA tetrasodium salt and EDTA sodium iron salt, and the added amount of the activating phase is preferably 0.1 to 0.3 parts based on 100 parts of the total weight of the monomers.

[0025] The method for preparing low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention comprises the following steps: the molecular weight regulator is at least one of tert-dodecyl mercaptan, n-dodecyl mercaptan and isopropyl dithiodimethylthionate; and the molecular weight regulator can be added once or in multiple times.

[0026] The preparation method of the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention, the initiator is a redox initiator, selected from at least one of dicumyl peroxide, cumyl peroxide, isopropyl n-butyl peroxide and isopropyl tert-butyl peroxide, preferably cumyl peroxide, before starting the polymerization reaction, based on 100 parts of the total weight of the monomers, the added amount of the initiator is preferably 0.05 to 0.2 parts.

[0027] The method for preparing the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention, the deoxidizer is selected from at least one of sodium dithionite, dimethyl ketoxime, isoascorbic acid, and carbohydrazide, and the present invention preferably uses sodium dithionite. Based on 100 parts by total weight of the monomers, the added amount of the deoxidizer is preferably 0.01 to 0.05 parts.

[0028] The present invention does not particularly limit the terminator, which may be at least one of diethylhydroxylamine, hydroquinone, and sodium thiamethoxam. The amount of the terminator added is preferably 0.3 to 0.5 parts based on 100 parts of the total weight of the monomers.

[0029] In the method for preparing the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention, the polymerization reaction temperature is 5.0-12.0°C, preferably 5.0-10.0°C.

[0030] The total weight of monomers described in the present invention refers to the total weight of the phenyl-containing acrylate monomer, acrylonitrile and butadiene monomer added before the polymerization reaction begins, excluding the phenyl-containing acrylate monomer added when the conversion rate reaches 25% to 30%, the acrylonitrile added when the polymerization conversion rate reaches 45% to 50%, and the phenyl-containing acrylate monomer added when the polymerization conversion rate reaches 60% to 65%.

[0031] The present invention also provides a low-temperature-resistant and wear-resistant ester-containing nitrile rubber obtained by the preparation method.

[0032] The present invention uses phenyl-containing acrylate as the third monomer, adopts low-temperature emulsion copolymerization method, and ternary copolymerizes it with acrylonitrile and butadiene. Through the process of adding initiator, acrylonitrile, molecular weight regulator and phenyl-containing acrylate monomer in multiple stages, the uniform distribution problem of nitrile group and ester group structure in ester-containing acrylonitrile rubber is improved. At the same time, the introduction of a small amount of phenyl-containing acrylate monomer makes the acrylonitrile rubber molecular chain contain phenyl and ester group structure at the same time, and the alkoxy carbon chain in the polymer improves the flexibility of the chain segment, significantly improves the low temperature resistance of the acrylonitrile rubber, and improves the stability of multiple deformations. The introduction of ester group structure improves the low temperature resistance and ozone stability of the polymer, and improves the mechanical property. The introduction of benzene ring can improve the rigidity of the molecular chain, improve the wear resistance and mechanical property of the polymer, and make the low temperature resistance and wear resistance of the ester-containing acrylonitrile rubber well balanced. At the same time, the method of adding phenyl-containing acrylic ester monomer, acrylonitrile, initiator and molecular weight regulator in multiple stages is adopted to improve the combination rate of acrylonitrile and phenyl-containing acrylic ester monomer, improve the random distribution of nitrile group and ester group in the polymer, and the ester group structure content of the prepared ester-containing nitrile rubber is greater than 6wt%, the Mooney viscosity is less than 80, the tensile strength is greater than 22MPa, the glass transition temperature is less than -40℃, the thermal weight loss temperature is greater than 330℃, and the Akron wear volume is less than 0.24cm 3 , with excellent properties such as low temperature resistance and wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the nuclear magnetic resonance spectrum of the low-temperature-resistant and wear-resistant ester-containing nitrile rubber prepared in Example 3. DETAILED DESCRIPTION

[0034] The following is a detailed description of the embodiments of the present invention: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and process are given, but the protection scope of the present invention is not limited to the following embodiments. The experimental methods in the following embodiments without specifying specific conditions are usually carried out under conventional conditions.

[0035] Evaluation and analysis methods:

[0036] Bound acrylonitrile content: tested in accordance with SH / T 1157.2-2015.

[0037] Bound ester structure content: obtained by integrating the peak area of ​​the NMR spectrum.

[0038] Mooney viscosity: Prepare the sample according to 8.3.2.2 (roller method) of GB / T 15340-2008, and test the raw rubber according to GB / T1232.1-2016.

[0039] Glass transition temperature: DSC method is used to test raw rubber according to SH / T 1771-2010.

[0040] Thermal weight loss temperature: Test raw rubber according to GB / T14837.2-2014.

[0041] Akron wear volume: Prepare vulcanized rubber wheel samples with a diameter of 68 mm, a thickness of (12.7 ± 0.2) mm, and a center hole diameter of (13.0 ± 0.2) mm. The rotation speed of the rubber wheel shaft is (76 ± 2) r / min, and the rotation speed of the grinding wheel shaft is (34 ± 1) r / min. Before the test, the rubber wheel is pre-grinded for 15 minutes and then weighed. Then the sample is weighed after traveling 1.61 km.

[0042] Tensile strength: measured in accordance with GB / T 528-2009.

[0043] Example 1

[0044] In a 10L polymerization reactor, add 4 parts of emulsifier (sodium dodecylbenzene sulfonate and disproportionated rosin potassium soap in a ratio of 3:1), 160 parts of desalted water, 0.2 parts of Diaobaikuai-EDTA tetrasodium salt, 0.2 parts of n-dodecyl mercaptan, 14 parts of acrylonitrile, 5 parts of ethyl acrylate monomer into the polymerization reactor, evacuate and replace with nitrogen, repeat 3 times, add 0.01 parts of sodium dithionate, add 81 parts of butadiene monomer. When the temperature of the polymerization reactor is maintained at 5°C, add 0.1 parts of cumene peroxide to start the polymerization reaction.

[0045] When the conversion rate reaches 25%, add 1 part of styrene ethyl acrylate monomer; when the polymerization conversion rate reaches 50%, add 1 part of acrylonitrile, 0.003 parts of isopropyl peroxide and 0.04 parts of tert-dodecyl mercaptan; when the polymerization conversion rate reaches 60%, add 1 part of styrene ethyl acrylate monomer; continue to react until the polymerization conversion rate reaches 85%, add 0.3 parts of diethylhydroxylamine, continue to stir and react for half an hour, and then discharge the material. The latex obtained by the reaction is condensed, washed and dried to obtain a low-temperature and wear-resistant special nitrile rubber containing phenyl and ester groups.

[0046] Example 2

[0047] In a 10L polymerization reactor, add 6 parts of emulsifier (sodium dodecylbenzene sulfonate and disproportionated rosin potassium soap in a ratio of 4:1), 180 parts of desalted water, 0.24 parts of Diaobaikuai-EDTA tetrasodium salt, 0.2 parts of n-dodecyl mercaptan, 13 parts of acrylonitrile and 6 parts of ethyl acrylate monomer into the polymerization reactor, evacuate and replace with nitrogen, repeat 3 times, add 0.01 parts of sodium dithionite, add 81 parts of butadiene monomer. When the polymerization reactor temperature is maintained at 7.5°C, add 0.1 parts of cumene peroxide to carry out polymerization reaction.

[0048] When the polymerization conversion rate is 30%, 2 parts of phenylethyl acrylate monomer are added; when the polymerization conversion rate reaches 45%, 2 parts of acrylonitrile, 0.004 parts of isopropylbenzene peroxide and 0.04 parts of n-dodecyl mercaptan are added; when the polymerization conversion rate is 63%, 2 parts of phenylethyl acrylate monomer are added. Continue the reaction until the polymerization conversion rate reaches 80%, add 0.4 parts of diethylhydroxylamine, continue stirring and reacting for half an hour, and then discharge the material. The latex obtained by the reaction is condensed, washed and dried to obtain a low-temperature and wear-resistant ester-containing nitrile rubber containing phenyl and ester groups.

[0049] Example 3

[0050] In a 10L polymerization reactor, add 8 parts of emulsifier (sodium dodecylbenzene sulfonate and disproportionated rosin potassium soap in a ratio of 4:1), 200 parts of desalted water, 0.3 parts of Diaobakua-EDTA tetrasodium salt, 0.2 parts of n-dodecyl mercaptan, 17 parts of acrylonitrile and 14 parts of styrene ethyl acrylate monomer, evacuate and replace with nitrogen, repeat 3 times, add 0.01 parts of sodium dithionite, add 69 parts of butadiene monomer. When the temperature of the polymerization reactor is maintained at 7.5°C, add 0.1 parts of cumene peroxide to start the polymerization reaction.

[0051] When the polymerization conversion rate is 28%, add 1 part of phenylethyl acrylate monomer; when the polymerization conversion rate reaches 47%, add 3 parts of acrylonitrile, 0.005 parts of isopropyl peroxide and 0.06 parts of n-dodecyl mercaptan; when the polymerization conversion rate is 65%, add 1 part of phenylethyl acrylate monomer; continue to react until the polymerization conversion rate reaches 83%, add 0.5 parts of diethylhydroxylamine, continue to stir and react for half an hour, and discharge the material. The latex obtained by the reaction is condensed, washed and dried to obtain a low-temperature and wear-resistant ester-containing nitrile rubber containing phenyl and ester groups.

[0052] Example 4

[0053] In a 10L polymerization reactor, add 8 parts of emulsifier (sodium dodecylbenzene sulfonate and disproportionated rosin potassium soap in a ratio of 4:1), 200 parts of desalted water, 0.3 parts of Diaobaikuai-EDTA tetrasodium salt, 0.2 parts of n-dodecyl mercaptan, 18 parts of acrylonitrile and 14 parts of 4-ethylbenzene acrylate monomer into the polymerization reactor, evacuate and replace with nitrogen, repeat 3 times, add 0.01 parts of sodium dithionate, add 68 parts of butadiene monomer. When the temperature of the polymerization reactor is maintained at 7.5°C, add 0.1 parts of cumene peroxide to start the polymerization reaction.

[0054] When the polymerization conversion rate is 25%, add 1 part of 4-ethylbenzene acrylate monomer; when the polymerization conversion rate reaches 45%, add 2 parts of acrylonitrile, 0.005 parts of isopropylbenzene peroxide and 0.05 parts of n-dodecyl mercaptan; when the polymerization conversion rate is 60%, add 1 part of 4-ethylbenzene acrylate monomer; continue to react until the polymerization conversion rate reaches 85%, add 0.5 parts of diethylhydroxylamine, continue to stir and react for half an hour, and discharge the material. The latex obtained by the reaction is condensed, washed and dried to obtain a low-temperature and wear-resistant ester-containing nitrile rubber containing phenyl and ester groups.

[0055] Example 5

[0056] In a 10L polymerization reactor, add 8 parts of emulsifier (sodium dodecylbenzene sulfonate and disproportionated rosin potassium soap in a ratio of 4:1), 210 parts of desalted water, 0.3 parts of Diaobaikuai-EDTA tetrasodium salt, 0.3 parts of n-dodecyl mercaptan, 18 parts of acrylonitrile and 14 parts of benzyl acrylate monomer, evacuate and replace with nitrogen, repeat 3 times, add 0.01 parts of sodium dithionite, add 68 parts of butadiene monomer. When the polymerization reactor temperature is maintained at 7.5°C, add 0.105 parts of cumene peroxide to start the polymerization reaction.

[0057] When the polymerization conversion rate is 25%, add 1 part of benzyl acrylate monomer; when the polymerization conversion rate reaches 45%, add 2 parts of acrylonitrile, 0.003 parts of isopropyl peroxide and 0.04 parts of n-dodecyl mercaptan; when the polymerization conversion rate is 60%, add 1 part of benzyl acrylate monomer; continue to react until the polymerization conversion rate reaches 85%, add 0.3 parts of hydroquinone, continue to stir and react for half an hour, and then discharge the material. The latex obtained by the reaction is condensed, washed and dried to obtain a low-temperature and wear-resistant ester-containing nitrile rubber containing phenyl and ester groups.

[0058] Example 6

[0059] In a 10L polymerization reactor, add 7 parts of emulsifier (sodium dodecylbenzene sulfonate and disproportionated rosin potassium soap in a ratio of 4:1), 200 parts of desalted water, 0.3 parts of Diaobakua-EDTA tetrasodium salt, 0.4 parts of n-dodecyl mercaptan, 17 parts of acrylonitrile and 15 parts of styrene ethyl acrylate monomer, evacuate and replace with nitrogen, repeat 3 times, add 0.05 parts of sodium dithionite, add 68 parts of butadiene monomer. When the polymerization reactor temperature is maintained at 7.5°C, add 0.1 parts of cumene peroxide to start the polymerization reaction.

[0060] When the polymerization conversion rate is 25%, add 1 part of phenylethyl acrylate monomer; when the polymerization conversion rate reaches 48%, add 3 parts of acrylonitrile, 0.005 parts of isopropylbenzene peroxide and 0.03 parts of n-dodecyl mercaptan; when the polymerization conversion rate is 63%, add 4 parts of phenylethyl acrylate monomer; continue to react until the polymerization conversion rate reaches 85%, add 0.4 parts of diethylhydroxylamine, continue to stir and react for half an hour, and discharge the material. The latex obtained by the reaction is condensed, washed and dried to obtain a low-temperature and wear-resistant ester-containing nitrile rubber containing phenyl and ester groups.

[0061] Example 7

[0062] In a 10L polymerization reactor, add 6 parts of emulsifier (sodium dodecylbenzene sulfonate and disproportionated rosin potassium soap in a ratio of 4:1), 200 parts of desalted water, 0.2 parts of Diaobaikuai-EDTA tetrasodium salt-EDTA iron sodium salt, 0.7 parts of n-dodecyl mercaptan, 25 parts of acrylonitrile and 5 parts of styrene ethyl acrylate monomer, evacuate and replace with nitrogen, repeat 3 times, add 0.03 parts of sodium dithionite, add 70 parts of butadiene monomer. When the polymerization reactor temperature is maintained at 10.0°C, add 0.05 parts of cumene peroxide to start the polymerization reaction.

[0063] When the polymerization conversion rate is 25%, add 1 part of phenylethyl acrylate monomer; when the polymerization conversion rate reaches 50%, add 4 parts of acrylonitrile, 0.005 parts of isopropyl peroxide and 0.06 parts of n-dodecyl mercaptan; when the polymerization conversion rate is 60%, add 1 part of phenylethyl acrylate monomer; continue to react until the polymerization conversion rate reaches 83%, add 0.3 parts of diethylhydroxylamine, continue to stir and react for half an hour, and discharge the material. The latex obtained by the reaction is condensed, washed and dried to obtain a low-temperature and wear-resistant ester-containing nitrile rubber containing phenyl and ester groups.

[0064] Example 8

[0065] In a 10L polymerization reactor, add 8 parts of emulsifier (sodium dodecylbenzene sulfonate and disproportionated rosin potassium soap in a ratio of 4:1), 200 parts of desalted water, 0.1 parts of Diaobakua-EDTA tetrasodium salt, 0.7 parts of n-dodecyl mercaptan, 113 parts of acrylonitrile and 25 parts of styrene ethyl acrylate monomer, evacuate and replace with nitrogen, repeat 3 times, add 0.05 parts of sodium dithionite, add 62 parts of butadiene monomer. When the polymerization reactor temperature is maintained at 5.0°C, add 0.2 parts of cumene peroxide to start the polymerization reaction.

[0066] When the polymerization conversion rate is 25%, add 1 part of phenylethyl acrylate monomer; when the polymerization conversion rate reaches 45%, add 4 parts of acrylonitrile, 0.002 parts of isopropyl peroxide and 0.06 parts of n-dodecyl mercaptan; when the polymerization conversion rate is 60%, add 1 part of phenylethyl acrylate monomer; continue to react until the polymerization conversion rate reaches 85%, add 0.5 parts of diethylhydroxylamine, continue to stir and react for half an hour, and then discharge the material. The latex obtained by the reaction is condensed, washed and dried to obtain a low-temperature and wear-resistant ester-containing nitrile rubber containing phenyl and ester groups.

[0067] In order to characterize the structural characteristics of the low temperature and wear resistant ester-containing nitrile rubber of the present invention, the ester-containing nitrile rubber raw rubber in Example 3 was subjected to nuclear magnetic hydrogen spectrum measurement. The test results are as follows: Figure 1 shown.

[0068] from Figure 1 The hydrogen nuclear magnetic spectrum shows that: 1 HNMR (400 MHz, CDCl 3 ) The peak at δ2.50 (1) is CN-CH- next to the nitrile group, and the peak at δ5.34 (2) is -COO-CH next to the ester group. 2 -, the peak at δ7.33(3) is -CH- on the benzene ring, which proves that the phenylethyl acrylate modified nitrile rubber was successfully prepared.

[0069] In order to characterize the basic properties of the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention, the properties of the low-temperature-resistant and wear-resistant ester-containing nitrile rubber prepared in Examples 1 to 8 were measured. The test results are shown in Table 1.

[0070] Table 1:

[0071]

[0072] As can be seen from Table 1, the ester-containing nitrile rubbers prepared in Examples 1 to 5 have a combined ester structure content of >6.00 wt%, a Mooney viscosity of <80.0, a tensile strength of >22.0 MPa, a glass transition temperature of <-40.0°C, a thermal weight loss temperature of >330°C, and an Akron wear volume of less than 0.24 cm 3This shows that the ester-containing nitrile rubber has good low-temperature resistance as well as excellent wear resistance and mechanical properties.

[0073] In order to characterize the effects of multi-point addition of monomers and additives on the performance of the ester-containing nitrile rubber in the low-temperature-resistant and wear-resistant ester-containing nitrile rubber of the present invention, relevant data were compared with comparative examples under different conditions with reference to Example 3. The specific method of the comparative example is as follows.

[0074] Comparative Example 1

[0075] Compared with Example 3, the difference is that the emulsifier in Comparative Example 1 uses sodium dodecylbenzene sulfonate as a single emulsifier, and the rest is the same as Example 3. The performance test results of the prepared product are listed in Table 2.

[0076] Comparative Example 2

[0077] Compared with Example 3, the difference is that Comparative Example 2 adopts a one-time feeding method without additional feeding. The rest is the same as Example 3. The performance test results of the prepared products are listed in Table 2.

[0078] In a 10L polymerization reactor, add 8 parts of emulsifier (sodium dodecylbenzene sulfonate and disproportionated rosin potassium soap in a ratio of 4:1), 200 parts of desalted water, 0.3 parts of Diaobaikuai-EDTA tetrasodium salt, 0.26 parts of n-dodecyl mercaptan, 20 parts of acrylonitrile and 16 parts of ethyl acrylate monomer, evacuate and replace with nitrogen, repeat 3 times, add 0.01 parts of sodium dithionite, add 64 parts of butadiene monomer. When the polymerization reactor temperature is maintained at 7.5°C, add 0.105 parts of isopropyl peroxide to start the polymerization reaction. When the polymerization conversion rate reaches 85%, add 0.5 parts of diethylhydroxylamine, continue stirring the reaction for half an hour and discharge the material. The latex obtained by the reaction is condensed, washed and dried to obtain a low-temperature wear-resistant ester-containing nitrile rubber containing phenyl and ester groups.

[0079] Comparative Example 3

[0080] Compared with Example 3, the difference is that the phenethyl acrylate monomer of Comparative Example 3 is added at one time, and the rest is the same as Example 3. The performance test results of the prepared product are listed in Table 2.

[0081] Comparative Example 4

[0082] Compared with Example 3, the difference is that the cumene peroxide in Comparative Example 4 is added at one time, and the rest is the same as Example 3. The performance test results of the prepared product are listed in Table 2.

[0083] Comparative Example 5

[0084] Compared with Example 3, the difference is that in Comparative Example 5, the phenylethyl acrylate monomer is replaced by butyl acrylate monomer, and the rest is the same as Example 3. The performance test results of the prepared product are listed in Table 2.

[0085] Comparative Example 6

[0086] Compared with Example 3, the difference is that in Example 6, no phenylethyl acrylate monomer is added, and acrylonitrile is added when the polymerization conversion rate is 28% and 65%. Others are the same as in Example 3. The performance test results of the prepared products are listed in Table 2.

[0087] In a 10L polymerization reactor, add 8 parts of emulsifier (sodium dodecylbenzene sulfonate and disproportionated rosin potassium soap in a ratio of 4:1), 200 parts of desalted water, 0.3 parts of Diaobakua-EDTA tetrasodium salt, 0.2 parts of n-dodecyl mercaptan, 17 parts of acrylonitrile, evacuate and replace with nitrogen, repeat 3 times, add 0.01 parts of sodium dithionite, add 83 parts of butadiene monomer. When the polymerization reactor temperature is maintained at 7.5°C, add 0.1 parts of cumene peroxide to start the polymerization reaction.

[0088] When the polymerization conversion rate is 28%, add 1 part of acrylonitrile; when the polymerization conversion rate reaches 47%, add 3 parts of acrylonitrile, 0.005 parts of isopropyl benzene peroxide and 0.06 parts of n-dodecyl mercaptan; when the polymerization conversion rate is 65%, add 1 part of acrylonitrile; continue to react until the polymerization conversion rate reaches 83%, add 0.5 parts of diethylhydroxylamine, continue to stir and react for half an hour, and discharge the material. The latex obtained by the reaction is condensed, washed and dried to obtain a low-temperature and wear-resistant ester-containing nitrile rubber containing phenyl and ester groups.

[0089] The properties of the ester-containing nitrile rubber prepared in Example 3 and Comparative Examples 1-6 are shown in Table 2.

[0090] Table 2:

[0091]

[0092] It can be seen from Table 2 that the composite emulsifier can improve the dispersibility and stability of the polymerization emulsification system and increase the binding rate of acrylonitrile and phenyl-containing acrylic ester monomers; the use of one-time addition will lead to a fast polymerization rate of acrylonitrile with a high reactivity rate in the initial stage of the reaction, uneven distribution of nitrile groups in the molecular chain, and reduced binding rate of ester monomers, resulting in poor low temperature resistance and wear resistance of ester-containing nitrile rubber;

[0093] Compared with adding the phenyl-containing acrylate monomer all at once, adding in stages is beneficial to increasing the binding rate of the phenyl-containing acrylate monomer and improving the distribution of the ester group in the molecular chain, thereby improving the polymer performance; when the initiator is added all at once, the initial polymerization rate is fast and the later reaction is slow, resulting in a longer reaction time.

[0094] Compared with Example 3, when butyl acrylate is used in Comparative Example 5, the low-temperature resistance of the nitrile rubber is better, but the mechanical properties and wear resistance are not good. This is because butyl acrylate will increase the flexibility of the molecular chain when combined with the molecular chain, and phenylethyl acrylate will weaken the flexibility of the molecular chain due to the presence of the benzene ring structure, and increase a certain rigidity, thereby improving the wear resistance and mechanical properties, and making it have both low-temperature resistance and wear resistance.

[0095] In Comparative Example 6, the glass transition temperature (-28°C) and the Akron wear volume (0.24 cm 3 ) are significantly lower than those in Example 3 (-53.7℃ and 0.13cm 3 ), which further illustrates that the introduction of styrene ethyl acrylate can improve and well balance the low temperature resistance and wear resistance of nitrile rubber, so it has a good application prospect.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a low-temperature-resistant and wear-resistant ester-containing nitrile rubber, characterized in that: The following steps are involved: In a polymerization kettle, water, emulsifier, activating phase, phenyl-containing acrylate monomer, acrylonitrile and molecular weight regulator are added, and after vacuuming and nitrogen replacement for several times, deoxidizer and butadiene monomer are added, and initiator is added to start polymerization reaction; when the conversion rate reaches 25% to 30%, phenyl-containing acrylate monomer is added, and when the polymerization conversion rate reaches 45% to 50%, acrylonitrile, initiator and molecular weight regulator are added; when the polymerization conversion rate reaches 60% to 65%, phenyl-containing acrylate monomer is added; the reaction is continued until the polymerization conversion rate reaches 80% to 85%, a terminator is added, the reaction is continued with stirring, and the material is discharged. After the latex obtained by the reaction is condensed, washed and dried, a low-temperature-resistant and wear-resistant ester-containing nitrile rubber is obtained.

2. The preparation method according to claim 1, characterized in that: The phenyl-containing acrylate monomer is selected from at least one of benzyl acrylate, phenylethyl acrylate, phenoxyethyl acrylate, and 4-ethylphenyl acrylate; before starting the polymerization reaction, the amount of the phenyl-containing acrylate monomer added is 3.0 to 25.0 parts based on 100 parts of the total weight of the monomers.

3. The preparation method according to claim 1, characterized in that: Before starting the polymerization reaction, the amount of acrylonitrile added is 13.0 to 25.0 parts based on 100 parts of the total weight of the monomers.

4. The preparation method according to claim 1, characterized in that: Before starting the polymerization reaction, the molecular weight regulator is added in an amount of 0.2 to 0.7 parts based on 100 parts of the total weight of the monomers.

5. The preparation method according to claim 1, characterized in that: When the polymerization conversion rate reaches 25% to 30%, based on 100 parts of the total weight of the monomers, the weight of the additional phenyl-containing acrylate monomer is 1 to 2 parts.

6. The preparation method according to claim 1, characterized in that: When the polymerization conversion rate reaches 45% to 50%, based on 100 parts of the total weight of the monomers, the weight of the additional acrylonitrile is 1 to 4 parts, the weight of the additional initiator is 0.002 to 0.006 parts, and the weight of the additional molecular weight regulator is 0.03 to 0.06 parts.

7. The preparation method according to claim 1, characterized in that: When the polymerization conversion rate reaches 60% to 65%, based on 100 parts of the total weight of the monomers, the weight of the additional phenyl-containing acrylate monomer is 1 to 4 parts.

8. The preparation method according to claim 1, characterized in that: The emulsifier is a compound of sodium dodecylbenzene sulfonate and disproportionated rosin potassium soap, the compounding ratio is 3-4:1, and the addition amount of the emulsifier is 4.0-8.0 parts based on 100 parts of the total weight of the monomers.

9. The preparation method according to claim 1, characterized in that: The activating phase is at least one of diatomaceous earth, EDTA tetrasodium salt, and EDTA sodium iron salt. Based on 100 parts of the total weight of the monomers, the added amount of the activating phase is preferably 0.1 to 0.3 parts.

10. The preparation method according to claim 1, characterized in that: The molecular weight regulator is at least one of tert-dodecyl mercaptan, n-dodecyl mercaptan and isopropyl dithiodimethylthionate, and the molecular weight regulator is added once or in multiple times.

11. The preparation method according to claim 1, characterized in that: The initiator is selected from at least one of diisopropyl peroxide, cumene peroxide, isopropyl n-butyl peroxide and isopropyl tert-butyl peroxide. Before starting the polymerization reaction, the amount of the initiator added is 0.05 to 0.2 parts based on 100 parts of the total weight of the monomers.

12. The preparation method according to claim 1, characterized in that: The deoxidizer is selected from at least one of sodium dithionite, dimethyl ketoxime, isoascorbic acid and carbohydrazide. The amount of the deoxidizer added is 0.01 to 0.05 parts based on 100 parts of the total weight of the monomers.

13. The preparation method according to claim 1, characterized in that: The terminator is selected from at least one of diethylhydroxylamine, hydroquinone and sodium thiamethoxam. The amount of the terminator added is 0.3 to 0.5 parts based on 100 parts of the total weight of the monomers.

14. The preparation method according to claim 1, characterized in that: The polymerization reaction temperature is 5.0-12.0°C.

15. A low-temperature-resistant and wear-resistant ester-containing nitrile rubber obtained by the preparation method according to any one of claims 1 to 14.

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