A nitrile rubber, a method for preparing the same and use thereof

Abstract

The application relates to the technical field of synthetic rubber, in particular to a nitrile rubber and a preparation method and application thereof. 10 ‑C 13 The composite emulsifier system is composed of linear alkyl benzene sulfonic acid and naphthalene sulfonic acid formaldehyde condensate sodium salt, and a high-temperature emulsion polymerization process is adopted, so that the obtained nitrile rubber has high tensile strength.

Description

Technical Field

[0001] This invention relates to the field of synthetic rubber technology, specifically to a nitrile rubber, a method for preparing nitrile rubber, and an application of nitrile rubber. Background Technology

[0002] Nitrile rubber (NBR) possesses excellent oil resistance, heat resistance, abrasion resistance, gas permeability resistance, high elongation modulus, hardness, and tensile strength, making it widely used in oil-resistant hoses for hydraulic transmission systems. NBR is a type of rubber produced by emulsion polymerization of butadiene and acrylonitrile, primarily using this method. Due to the presence of double bonds in the NBR molecule, the α-hydrogen atoms are highly reactive and prone to degradation under heat and oxygen, leading to changes in the material's molecular structure. During use, the rubber gradually ages, resulting in loss of elasticity and a decline in mechanical properties.

[0003] For many years, countries around the world have been conducting research on the synthesis of nitrile butadiene rubber (NBR). Currently, alkali metal salts of alkyl aryl sulfonic acids, alkali metal salts of fatty acids, rosin acid soaps and their mixed soaps are commonly used as emulsifiers in emulsion polymerization. For example, Idemitsu Petrochemical Co., Ltd. of Japan has developed a high-efficiency dispersant for NBR emulsion polymerization, which is composed of maleic acid (anhydride) and styrene sulfonate. Using this dispersant can improve the dispersibility of monomers and the stability of NBR. JSR Corporation of Japan uses nonionic surfactants such as polyethylene oxide alkyl ethers, polyethylene oxide fatty acid esters, polyethylene oxide sorbitol fatty acid esters, and ethylene oxide / propylene oxide block copolymers as emulsifiers. Zeon Corporation of Japan, by appropriately adjusting the polymerization temperature, using potassium persulfate as an initiator, potassium oleate, sodium dodecylbenzene sulfonate and other anionic or nonionic surfactants such as polyethylene oxide alkyl ethers as emulsifiers, and dodecyl mercaptan as a regulator, has produced NBR with a ML (1+4) temperature of 30-150°C at 100°C, a molecular weight distribution index of 5-8, a gel content of less than 5%, and a bound acrylonitrile content of 10%-45%, for use in the rubber roller and other rubber product industries.

[0004] Chinese Patent Publication No. CN103450399A discloses a method for preparing nitrile rubber by emulsion polymerization. The polymerization includes at least the following steps: adding a portion of acrylonitrile, a portion of emulsifier, a portion of regulator, and an initiator to a polymerization reactor; adding butadiene under vacuum; carrying out emulsion polymerization under stirring; adding a portion of emulsifier, crosslinking agent, and acrylonitrile to the polymerization reactor when the polymerization conversion rate reaches 25-40% in the middle stage of the reaction; and adding the remaining portion of emulsifier and regulator when the polymerization conversion rate reaches 60-75% in the later stage of the reaction. The crosslinking agent is one or more of the following: triallyl isocyanurate, triallyl cyanurate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol diacrylate, and polyethylene glycol dimethacrylate; the amount of crosslinking agent added is 0.1-3.0 parts. The emulsifier is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, potassium stearate, potassium oleate, and disproportionated rosin potassium soap. The resulting nitrile rubber has a high microgel content and low gel content, making it easy to form a three-dimensional structure during processing. This results in good physical and mechanical properties of the rubber product, increased Mooney viscosity, and consequently, improved tensile strength and 300% elongation stress. The tensile strength can reach 19-24 MPa.

[0005] Chinese Patent Publication No. CN116925288A discloses a method for preparing high-strength special nitrile rubber. The method uses butadiene and acrylonitrile as polymerizing monomers, a binary compound emulsion system of sodium salt of dodecylbenzenesulfonic acid and naphthalenesulfonic acid formaldehyde condensate, persulfate as an initiator, and tert-dodecyl mercaptan as a molecular weight regulator. The method employs an intermittent feeding method with batch addition of molecular weight regulator, and a thermal polymerization process to synthesize nitrile rubber paste. Terminating agent and antioxidant are added, and the paste is then degassed, coagulated, washed, and dried to obtain a high-strength nitrile rubber product with a tensile strength ≥27.5 MPa.

[0006] Chinese Patent Publication No. CN103421146A discloses a method for preparing high acrylonitrile-content nitrile rubber. The method uses butadiene and acrylonitrile as polymerizing monomers, a ternary compound of disproportionated rosin acid potassium soap, potassium oleate soap, and sodium salt of naphthalenesulfonic acid formaldehyde condensate as emulsifiers, controls the free alkali content in the system with sodium hydroxide, uses persulfate as an initiator, and employs an intermittent feeding method with batch addition of molecular weight regulators. A thermal polymerization process is used to synthesize nitrile rubber paste. Terminator and antioxidant are added, and the product is obtained after degassing, coagulation, washing, and drying. The tensile strength of this nitrile rubber is ≥27.5 MPa.

[0007] Existing technologies all suffer from problems such as long polymerization reaction time, high power consumption of reaction equipment, a large number of fine rubber particles during agglomeration of nitrile rubber, difficulty in washing and drying during post-processing, and the inability of the obtained nitrile rubber to possess both excellent oil resistance and mechanical properties. Summary of the Invention

[0008] The purpose of this invention is to overcome the above-mentioned technical problems and provide a nitrile rubber, a method for preparing nitrile rubber, and an application of nitrile rubber. The preparation method uses a ternary compound emulsion system and a high-temperature emulsion polymerization process. The nitrile rubber obtained not only has high polymerization stability but also high tensile strength.

[0009] To achieve the above objectives, a first aspect of the present invention provides a method for preparing nitrile rubber, comprising: using butadiene and acrylonitrile as polymerization monomers in the presence of an initiator, employing a high-temperature emulsion polymerization method, wherein the composite emulsifier contains at least potassium disproportionated rosinate soap and / or sodium soap, C 10 -C 13 Sodium salts of linear alkylbenzene sulfonic acid and naphthalene sulfonic acid formaldehyde condensate, with molecular weight regulators added once or multiple times, are used to synthesize nitrile rubber paste. A terminator is added, and the paste is then degassed, coagulated, washed, and dried to obtain nitrile rubber.

[0010] This invention employs a specific composite emulsification system, wherein the composite emulsifier is a combination of at least three substances: disproportionated rosin acid soap, linear alkylbenzene sulfonic acid, and sodium salt of naphthalene sulfonic acid formaldehyde condensate.

[0011] Unless otherwise specified, all parts by weight in this invention are based on 100 parts by weight of total polymerized monomers.

[0012] The amount of composite emulsifier added in this invention can be the general amount of emulsifier added in the art, especially the amount used when anionic emulsifier and nonionic emulsifier are compounded. The preferred amount of composite emulsifier used in this invention is 2.5-7.3 parts, more preferably 2.8-5.8 parts.

[0013] This invention requires the addition of disproportionated rosin acid soap, which can be either potassium or sodium soap, to the composite emulsifier. The potassium or sodium disproportionated rosin acid soap in the composite emulsification system of this invention cannot be replaced by other anionic emulsifiers such as sodium decaalkyl sulfate, potassium oleate, and potassium stearate. This is because the inventors have discovered that, in the specific emulsion polymerization system of this invention, due to a synergistic effect, the addition of potassium or sodium disproportionated rosin acid soap increases the particle size of the polymer emulsion, which is particularly beneficial to the subsequent emulsion coagulation process after emulsion polymerization. The amount added can be adjusted according to the desired polymer emulsion particle size, especially the ease of emulsion coagulation after emulsion polymerization. Generally, the amount of potassium and / or sodium disproportionated rosin acid soap is increased when the acrylonitrile content is low. The recommended amount of potassium and / or sodium disproportionated rosin acid soap is 1.5-3.5 parts, more preferably 1.5-2.6 parts.

[0014] This invention requires the addition of C to the composite emulsifier. 10 -C 13Linear alkylbenzene sulfonic acid. The function of linear alkylbenzene sulfonic acid differs from that of sodium linear alkylbenzene sulfonate. Adding only sodium linear alkylbenzene sulfonate without linear alkylbenzene sulfonic acid results in a different effect than in this invention. This is because sodium alkylbenzene sulfonate is a saponification product of alkylbenzene sulfonic acid. Due to the use of alkylbenzene sulfonic acid, some alkylbenzene sulfonic acid remains incompletely saponified during its saponification process. A synergistic effect occurs between the two, improving the stability of the entire polymerization system and increasing the polymerization efficiency. Therefore, linear alkylbenzene sulfonic acid in the composite emulsion system of this invention cannot be replaced by sodium linear alkylbenzene sulfonate. As an emulsifier, C 10 -C 13 The most commonly used linear alkylbenzene sulfonic acid is dodecylbenzene sulfonic acid. 10 -C 13 The preferred amount of linear alkylbenzene sulfonic acid is 0.7-3.0 parts, more preferably 0.8-2.5 parts.

[0015] This invention requires sodium salt of naphthalenesulfonic acid formaldehyde condensate and C 10 -C 13 The simultaneous use of linear alkylbenzene sulfonic acid is a technique already existing in the art, and its usage is determined as needed; this invention does not impose any particular limitation. Failure to add it will lead to a decrease in the stability of the polymerization emulsion, and sludge formation may easily occur during polymerization. The preferred dosage of sodium naphthalenesulfonic acid formaldehyde condensate is 0.3-0.8 parts.

[0016] This invention also does not exclude the addition of other anionic emulsifiers or nonionic emulsifiers in the composite emulsion system, in addition to potassium or sodium disproportionated rosinate soap, linear alkylbenzene sulfonic acid and sodium salt of naphthalene sulfonic acid formaldehyde condensate. For example, at least one of sodium dodecylbenzene sulfonate, sodium decaalkyl sulfate, potassium oleate, potassium stearate, sorbitan tristearate and octylphenol polyoxyethylene ether may also be added.

[0017] The second aspect of the present invention provides a nitrile rubber prepared by the preparation method provided in the first aspect.

[0018] The third aspect of this invention provides an application of the nitrile rubber provided in the second aspect, which can be applied in the petrochemical, aerospace, and automotive fields, and is particularly suitable for the dynamic application environment of fuel oil.

[0019] Compared with the prior art, the present invention has the following advantages: This invention provides a simple method for preparing high-strength nitrile rubber, which employs a process containing at least potassium disproportionated rosinate soap and / or sodium soap, C 10 -C 13 A composite emulsifier system composed of sodium salt of linear alkylbenzene sulfonic acid and naphthalene sulfonic acid formaldehyde condensate, along with a high-temperature emulsion polymerization process, improves the polymerization conversion rate, reduces the energy consumption of the polymerization reaction, and solves the technical problems of numerous fine particles during coagulation and the difficulty of washing and drying in the post-processing. Detailed Implementation

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] The first aspect of this invention provides a method for preparing nitrile rubber, comprising: using butadiene and acrylonitrile as polymerization monomers in the presence of an initiator, employing a high-temperature emulsion polymerization method, wherein the composite emulsifier contains at least potassium disproportionated rosinate soap and / or sodium soap, C 10 -C 13 Sodium salts of linear alkylbenzene sulfonic acid and naphthalene sulfonic acid formaldehyde condensate, with molecular weight regulators added once or multiple times, are used to synthesize nitrile rubber paste. A terminator is added, and the paste is then degassed, coagulated, washed, and dried to obtain nitrile rubber.

[0022] Those skilled in the art will know that when emulsion polymerization of nitrile butadiene rubber uses a composite emulsion system, the emulsifier includes a primary emulsifier and a co-emulsifier. The primary emulsifier can be one or more anionic emulsifiers, such as at least one of potassium disproportionated rosinate, sodium dodecylbenzene sulfonate, sodium decaalkyl sulfate, potassium oleate, and potassium stearate, or other anionic emulsifiers. The co-emulsifier can be a nonionic emulsifier, such as at least one of sorbitan tristearate, sodium β-naphthalenesulfonate formaldehyde condensate, and octylphenol polyoxyethylene ether, or other nonionic emulsifiers.

[0023] However, this invention employs a specific composite emulsification system. This composite emulsifier is selected from at least three types: potassium disproportionated rosin acid soap and / or sodium soap, linear alkylbenzene sulfonic acid, and sodium naphthalene sulfonate formaldehyde condensate, which have a synergistic effect, thereby improving the stability of the latex in nitrile rubber. The amount of each component can be adjusted as needed. The amount of composite emulsifier added can be the commonly used amount in this technical field, especially when using anionic and nonionic emulsifiers in combination. Preferably, the amount of composite emulsifier is 2.5-7.3 parts by weight, more preferably 2.8-5.8 parts by weight.

[0024] In some embodiments of the present invention, more preferably, the amount of polymeric monomers, specifically potassium disproportionated rosinate soap and / or sodium soap, equivalent to 100 parts by weight, is 1.5-3.5 parts by weight; preferably C 10 -C 13The amount of linear alkylbenzene sulfonic acid used is 0.7-3.0 parts by weight; preferably, the amount of sodium salt of naphthalene sulfonic acid formaldehyde condensate is 0.3-0.8 parts by weight.

[0025] In this invention, 1.5-3.5 parts by weight of disproportionated rosinate potassium soap and / or sodium soap are preferably added to the composite emulsion system. For example, 1.0 parts by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, and any value within any range of any two values, preferably 1.5-2.6 parts by weight. The disproportionated rosinate potassium soap and / or sodium soap in the composite emulsion system of this invention can be replaced by other anionic emulsifiers such as sodium decaalkyl sulfate, potassium oleate, and potassium stearate. This is because the inventors unexpectedly discovered in experiments that, in the specific emulsion polymerization system of this invention, due to a synergistic effect, the addition of disproportionated rosinate potassium soap and / or sodium soap, in addition to emulsification, can also increase the particle size of the polymer emulsion, which is particularly beneficial to the subsequent emulsion coagulation process after emulsion polymerization.

[0026] In some specific embodiments of the present invention, potassium disproportionate soap and / or sodium disproportionate soap may be selected from potassium disproportionate soap, sodium disproportionate soap, or both potassium disproportionate soap and sodium disproportionate soap.

[0027] The present invention preferably adds C to the composite emulsion system. 10 -C 13 The linear alkylbenzene sulfonic acid is added in amounts of 0.7-3.0 parts by weight, for example, 0.5 parts by weight, 1 part by weight, 2 parts by weight, 2.5 parts by weight, 3.0 parts by weight, and any value within the range of any two values, preferably 0.8-2.5 parts by weight. In this invention, the linear alkylbenzene sulfonic acid and sodium linear alkylbenzene sulfonate have different functions; only C is added. 10 -C 13 Sodium linear alkylbenzene sulfonate without the addition of C 10 -C 13 Linear alkylbenzene sulfonic acid plays a different role than in this invention because sodium dodecylbenzene sulfonate is a saponification product of dodecylbenzene sulfonic acid. Due to the use of dodecylbenzene sulfonic acid, some dodecylbenzene sulfonic acid remains unsaponified during its saponification process. This results in a synergistic effect between the two, improving the stability of the entire polymerization system and increasing the polymerization efficiency. Therefore, linear alkylbenzene sulfonic acid in the composite emulsion system of this invention cannot be replaced by sodium linear alkylbenzene sulfonate.

[0028] In some specific embodiments of the present invention, C 10 -C 13 The linear alkylbenzene sulfonic acid is selected from at least one of decaalkylbenzene sulfonic acid, undecylbenzene sulfonic acid, dodecylbenzene sulfonic acid, and tridecylbenzene sulfonic acid, preferably dodecylbenzene sulfonic acid.

[0029] In this invention, 0.3-0.8 parts by weight of sodium naphthalenesulfonic acid formaldehyde condensate condensate is preferably added to the composite emulsion system, for example, 0.3 parts by weight, 0.45 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, or any value within any range of two such values. If sodium naphthalenesulfonic acid formaldehyde condensate condensate is not added, the stability of the polymer emulsion will decrease, and sludge formation will easily occur during the polymerization process.

[0030] In some specific embodiments of the present invention, the sodium salt of naphthalenesulfonate formaldehyde condensate includes, but is not limited to, sodium β-naphthalenesulfonate formaldehyde condensate.

[0031] In this invention, the composite emulsifier, in addition to disproportionated potassium rosinate soap and / or sodium soap, C 10 -C 13 In addition to sodium salts of linear alkylbenzene sulfonic acid and naphthalene sulfonic acid formaldehyde condensate, the compound emulsifier also contains other anionic and nonionic emulsifiers. Preferably, the compound emulsifier further contains at least one of sodium dodecylbenzene sulfonate, sodium decaalkyl sulfate, potassium oleate, potassium stearate, sorbitan tristearate, and octylphenol polyoxyethylene ether.

[0032] In some embodiments of the present invention, preferably, the composite emulsifier comprises potassium disproportionated rosinate soap and / or sodium soap, C 10 -C 13 It consists of sodium salt of linear alkylbenzene sulfonic acid and naphthalene sulfonic acid formaldehyde condensate.

[0033] In some embodiments of the present invention, preferably, the amount of composite emulsifier is 2.5-7.3 parts by weight relative to 100 parts by weight of polymeric monomer, for example, 2.0 parts by weight, 3.3 parts by weight, 4.5 parts by weight, 5.0 parts by weight, 6 parts by weight, 7.3 parts by weight, and any value within the range of any two values, preferably 2.8-5.8 parts by weight.

[0034] The synthesis scheme of nitrile rubber of the present invention is high-temperature emulsion polymerization. The polymerization temperature commonly used in the field of this technology is not particularly limited. Preferably, the conditions for high-temperature emulsion polymerization include: temperature of 25-35℃, preferably 25-40℃; and time of 10-30h, preferably 10-18h.

[0035] In some embodiments of the present invention, preferably, the amount of initiator is 0.1-0.5 parts by weight relative to 100 parts by weight of the polymerizing monomer, for example, 0.1 parts by weight, 0.2 parts by weight, 0.35 parts by weight, 0.5 parts by weight, and any value within a range of any two values, preferably 0.2-0.4 parts by weight. In the present invention, the amount of initiator is based on persulfate.

[0036] This invention does not particularly limit the initiator; any initiator commonly used in the high-temperature emulsion polymerization of nitrile rubber is acceptable. Preferably, the initiator is selected from persulfates, specifically potassium persulfate and ammonium persulfate. In this invention, the initiator includes, but is not limited to, potassium persulfate and ammonium persulfate.

[0037] This invention does not particularly limit the molecular weight regulator and its amount; generally, any molecular weight regulator and amount used for nitrile rubber can be used. Preferably, the molecular weight regulator is selected from molecular weight regulator butyl (diisopropyl xanthate) and / or tert-dodecyl mercaptan and / or n-dodecyl mercaptan, and more preferably from molecular weight regulator butyl (diisopropyl xanthate).

[0038] In this invention, the amount of molecular weight regulator can be adjusted according to the product performance requirements and the type of molecular weight regulator. Preferably, the amount of molecular weight regulator relative to 100 parts by weight of polymeric monomer is 0.3-1.0 parts by weight, for example 0.3 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.8 parts by weight, 1.0 parts by weight, and any value within any range of any two values, preferably 0.3-0.8 parts by weight.

[0039] In this invention, the molecular weight regulator is added once or multiple times during high-temperature emulsion polymerization, depending on the different performance requirements of the product. Preferably, the molecular weight regulator is added at least three times. The first addition is 30-35% of the total molecular weight regulator; when the reaction conversion rate reaches 35%-45%, the second addition is made, also 30-35% of the total molecular weight regulator; when the reaction conversion rate reaches 55%-65%, the third addition is made, including the remaining molecular weight regulator.

[0040] This invention does not particularly limit the type or amount of the terminator; any commonly used terminator may be used. Preferably, the terminator includes, but is not limited to, hydroquinone, sodium nitrite, hydroxylamine sulfate, or diethylhydroxylamine.

[0041] In some embodiments of the present invention, preferably, the amount of the terminator added is 0.05-0.15 parts by weight relative to 100 parts by weight of the polymeric monomer.

[0042] This invention does not specifically limit the timing of adding the terminator; the desired conversion rate of the nitrile butadiene rubber paste can be selected according to product requirements. Preferably, the terminator is added when the conversion rate of the high-temperature emulsion polymerization reaches 80% or more; more preferably, the terminator is added when the conversion rate of the high-temperature emulsion polymerization reaches 80-85%.

[0043] This invention also does not exclude the addition of other commonly used auxiliaries for nitrile emulsion polymerization, such as deionized water and electrolytes, to the polymerization system, provided that the addition amount is within the general addition range.

[0044] This invention does not particularly limit the type or amount of electrolyte added; any general electrolyte and general amount added will suffice. This invention also does not particularly limit the specific ratio of butadiene to acrylonitrile in the polymer monomers; any ratio commonly used in the preparation of nitrile rubber in existing technologies can be used (e.g., acrylonitrile content 15-65%).

[0045] The present invention also provides a preferred method for preparing nitrile rubber, comprising the following steps: based on 100 parts by weight of butadiene and acrylonitrile, the monomer composition is: 35-85 parts by weight of butadiene, 15-65 parts by weight of acrylonitrile, 200-280 parts by weight of deionized water; the composite emulsifier contains at least 1.5-3.5 parts by weight of potassium disproportionated rosin acid soap and / or sodium soap, 0.7-3.0 parts by weight of linear alkylbenzene sulfonic acid, and 0.3-0.8 parts by weight of sodium salt of naphthalene sulfonic acid formaldehyde condensate; the initiator is selected from persulfate initiators, and its dosage is 0.1-0.5 parts by weight; the molecular weight regulator is 0.3-1.0 parts by weight; the initiator is added at once; the monomer is added at once; the molecular weight regulator is added at least three times; and the polymerization temperature is 25-40℃. Preferably, the amount of composite emulsifier is 2.5-7.3 parts by weight relative to 100 parts by weight of polymeric monomer, and more preferably 2.8-5.8 parts by weight.

[0046] The present invention does not particularly limit the timing of adding the terminator, but can be determined according to the performance requirements of different products. It is preferred to add the terminator when the conversion rate of high-temperature emulsion polymerization reaches 80-85%.

[0047] The present invention also provides an optimal method for preparing nitrile rubber, comprising the following steps: after evacuating the polymerization reactor, deionized water, emulsifier, electrolyte, all monomers, and 30-35% molecular weight regulator are added; after controlling the temperature to 25-40°C, an initiator is added; when the reaction conversion rate reaches 35%-45%, a second molecular weight regulator is added; when the reaction conversion rate reaches 55%-65%, a third molecular weight regulator is added; when the conversion rate of high-temperature emulsion polymerization reaches 80-85%, a terminator is added; the material is discharged, and degassed, coagulated, washed, and dried to obtain nitrile rubber.

[0048] The second aspect of the present invention provides a nitrile rubber prepared by the preparation method provided in the first aspect.

[0049] In some embodiments of the present invention, preferably, based on the total content of nitrile rubber, the acrylonitrile content is 17-50 wt%, preferably 17-45 wt%, for example, 20 wt%, 28 wt%, 33 wt%, 40 wt%, 45 wt%, and any value within the range of any two values.

[0050] In some embodiments of the present invention, preferably, the method of the present invention can be used to obtain nitrile rubber with a latex particle size ≥100nm, preferably 110-130nm.

[0051] In some embodiments of the present invention, preferably, the Mooney viscosity ML can be obtained using the method of the present invention. ℃ Nitrile rubber with a strength of 50-120 and a tensile strength ≥18MPa.

[0052] In this invention, unless otherwise specified, the total solids content is measured according to SH / T1154-92; the acrylonitrile content is measured according to SH / T1157-1997; and the Mooney viscosity (ML) is... ℃ The tests were conducted according to GB / T1232-2000; the tensile strength test was conducted according to GB / T528-1998; and the elongation at break test was conducted according to GB / T528-1998.

[0053] As can be seen from the optimal production scheme in the examples, the preparation method of the present invention can produce a product with a bound acrylonitrile content of 17-50 wt% and a Mooney viscosity of ML. ℃ Nitrile rubber with a tensile strength ≥18 MPa and a thickness of 50-120.

[0054] The present invention will be described in detail below through embodiments.

[0055] Total solids were measured according to SH / T1154-92; Mooney viscosity ML ℃ The test was conducted according to GB / T1232-2000; The acrylonitrile content was determined using SH / T1157-1997. Tensile strength was measured according to GB / T528-1998; The elongation at break was measured according to GB / T 528-1998.

[0056] Example 1 A 10L polymerization reactor was evacuated and purged with nitrogen to a vacuum level of -0.1 MPa. Then, 220 parts by weight of deionized water, 83 parts by weight of butadiene, 17 parts by weight of acrylonitrile, a composite emulsifier (2.5 parts by weight of disproportionated rosin acid potassium soap, 0.9 parts by weight of dodecylbenzene sulfonic acid, and 0.45 parts by weight of naphthalenesulfonic acid formaldehyde condensate sodium salt), and 0.2 parts by weight of molecular weight regulator D were added sequentially. The temperature was then controlled, and when the reaction temperature reached 34°C, 0.25 parts by weight of potassium persulfate were added.

[0057] When the reaction conversion rate reaches 35-45%, add 0.2 parts by weight of secondary molecular weight regulator D; when the reaction conversion rate reaches 55-65%, add 0.2 parts by weight of tertiary molecular weight regulator D; when the reaction conversion rate reaches 82%, add 0.09 parts by weight of hydroquinone, discharge the material, and after degassing, coagulation, washing and drying, obtain nitrile rubber S1.

[0058] The physical properties of the aforementioned nitrile rubber S1 are listed in Table 3.

[0059] Examples 2-8 Following the method of Example 1, except that the amounts of each component and the polymerization conditions were as shown in Table 1, nitrile rubbers S2-S8 were obtained respectively.

[0060] The physical properties of the aforementioned nitrile rubbers S2-S8 are listed in Table 3.

[0061] Comparative Examples 1-8 Following the method of Example 1, except that the amounts of each component and the polymerization conditions were as shown in Table 2, nitrile rubbers DS1-DS8 were obtained respectively.

[0062] The physical properties of the aforementioned nitrile rubbers DS1-DS8 are listed in Table 4.

[0063] Table 1

[0064] Table 2

[0065] Table 3

[0066] Table 4

[0067] As shown in Tables 1-4, compared to Comparative Examples 1-8, the preparation method provided by this invention can yield a bound acrylonitrile content of 17-50 wt% and a Mooney viscosity of ML. ℃ Selected from nitrile rubber with a tensile strength ≥18MPa and a thickness of 50-120.

[0068] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing nitrile rubber, characterized in that, The preparation method includes at least the following steps: using butadiene and acrylonitrile as polymerization monomers in the presence of an initiator, employing a high-temperature emulsion polymerization method, wherein the composite emulsifier contains at least potassium disproportionated rosinate soap and / or sodium soap, C 10 -C 13 Sodium salt of linear alkylbenzene sulfonic acid and naphthalene sulfonic acid formaldehyde condensate, with a molecular weight regulator added once or multiple times, is used to synthesize nitrile rubber paste. A terminator is added, and the paste is then degassed, coagulated, washed, and dried to obtain nitrile rubber. Based on a total amount of butadiene and acrylonitrile added of 100 parts by weight, the amount of the composite emulsifier is preferably 2.5-7.3 parts by weight, more preferably 2.8-5.8 parts by weight.

2. The method for preparing nitrile rubber according to claim 1, characterized in that, Relative to 100 parts by weight of polymeric monomers, the amount of potassium disproportionated rosinate soap and / or sodium disproportionated rosinate soap in the composite emulsifier is 1.5-3.5 parts by weight, preferably 1.5-2.6 parts by weight.

3. The method for preparing nitrile rubber according to claim 1, characterized in that, Relative to 100 parts by weight of polymeric monomers, in the composite emulsifier, C 10 -C 13 The amount of linear alkylbenzene sulfonic acid used is 0.7-3.0 parts by weight, preferably C. 10 -C 13 The amount of linear alkylbenzene sulfonic acid used is 0.8-2.5 parts by weight; And / or, the C 10 -C 13 The linear alkylbenzene sulfonic acid is selected from at least one of decaalkylbenzene sulfonic acid, undecylbenzene sulfonic acid, dodecylbenzene sulfonic acid, and tridecylbenzene sulfonic acid, preferably dodecylbenzene sulfonic acid.

4. The method for preparing nitrile rubber according to claim 1, characterized in that, Relative to 100 parts by weight of the polymeric monomer, the amount of sodium naphthalenesulfonic acid formaldehyde condensate in the composite emulsifier is 0.3-0.8 parts by weight, preferably 0.3-0.7 parts by weight. And / or, the sodium salt of the naphthalenesulfonate formaldehyde condensate is selected from the sodium β-naphthalenesulfonate formaldehyde condensate.

5. The method for preparing nitrile rubber according to claim 1, characterized in that, The composite emulsifier also contains at least one of sodium dodecylbenzenesulfonate, sodium decaalkyl sulfate, potassium oleate, potassium stearate, sorbitan tristearate, and octylphenol polyoxyethylene ether.

6. The method for preparing nitrile rubber according to any one of claims 1-5, characterized in that, The conditions for high-temperature emulsion polymerization include a temperature of 25-40℃, preferably 30-35℃.

7. The method for preparing nitrile rubber according to claim 6, characterized in that, The amount of the initiator relative to 100 parts by weight of the polymerizable monomer is 0.1-0.5 parts by weight, preferably 0.2-0.4 parts by weight; And / or, the initiator is selected from persulfate initiators, preferably water-soluble initiators such as potassium persulfate and ammonium persulfate.

8. The method for preparing nitrile rubber according to claim 7, characterized in that, The amount of the molecular weight regulator relative to 100 parts by weight of the polymeric monomer is 0.3-1.0 parts by weight, preferably 0.3-0.8 parts by weight; And / or, the molecular weight regulator is selected from molecular weight regulator butyl (diisopropyl xanthate) and / or tert-dodecyl mercaptan and / or n-dodecyl mercaptan, preferably molecular weight regulator butyl (diisopropyl xanthate). And / or, the molecular weight regulator is added at least three times, with the first addition being 30-35% of the total molecular weight regulator amount; And / or, the molecular weight regulator is added at least three times, and when it is added twice, the total molecular weight regulator is added at 30-35% when the conversion rate of the high-temperature emulsion polymerization reaches 35-45%; And / or, the molecular weight regulator is added at least three times, with the remaining molecular weight regulator added when the conversion rate of the high-temperature emulsion polymerization reaches 55-65%.

9. The method for preparing nitrile rubber according to claim 8, characterized in that, When the conversion rate of the high-temperature emulsion polymerization reaches 80% or more, preferably 80-85%, the terminator is added; And / or, relative to 100 parts by weight of the polymerizing monomer, the amount of the terminator added is 0.05-0.15 parts by weight; And / or, the terminating agent is selected from any one of hydroquinone, sodium nitrite, hydroxylamine sulfate, or diethylhydroxylamine.

10. The method for preparing nitrile rubber according to claim 1 or 2, characterized in that, The amount of acrylonitrile used is 15-65 parts by weight, preferably 15-60 parts by weight, relative to 100 parts by weight of polymeric monomer. More preferably, the amount of acrylonitrile used is 15-55 parts by weight and the amount of butadiene used is 45-85 parts by weight relative to 100 parts by weight of polymeric monomers.

11. The method for preparing nitrile rubber according to claim 10, characterized in that, The preparation method includes the following steps: Based on 100 parts by weight of butadiene and acrylonitrile, the monomer composition is: 35-85 parts by weight of butadiene, 15-65 parts by weight of acrylonitrile, and 200-280 parts by weight of deionized water. The composite emulsifier contains at least 1.5-3.5 parts by weight of potassium disproportionated rosinate soap and / or sodium soap, 0.7-3.0 parts by weight of linear alkylbenzene sulfonic acid, and 0.3-0.8 parts by weight of sodium salt of naphthalene sulfonic acid formaldehyde condensate to form an emulsion system. The initiator is selected from persulfate initiators, and its dosage is 0.1-0.5 parts by weight. The initiator is added at once. The monomer is added at once. The molecular weight regulator is added at least three times, with a dosage of 0.3-1.0 parts by weight. The polymerization temperature is 25-40℃. Preferably, the amount of the composite emulsifier is 2.5-7.3 parts by weight, more preferably 2.8-5.8 parts by weight, relative to 100 parts by weight of the polymeric monomer.

12. The method for preparing nitrile rubber according to claim 11, characterized in that, The preparation method includes the following steps: after evacuating the polymerization reactor, deionized water, emulsifier, all monomers, and 30-35% molecular weight regulator are added. After controlling the temperature to 25-40℃, the initiator is added. When the conversion rate of the high-temperature emulsion polymerization reaches 30-35%, 30-35% molecular weight regulator is added. When the reaction conversion rate reaches 55-65%, the remaining molecular weight regulator is added. When the conversion rate of the high-temperature emulsion polymerization reaches 80-85%, the terminator is added. The material is discharged, and degassing, coagulation, washing, and drying are performed to obtain the nitrile rubber.

13. The nitrile rubber prepared by the method of claim 12.

14. The application of the nitrile rubber according to claim 13 in a dynamic operating environment of fuel oil.

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