Silicon copolymerization modified nitrile rubber and preparation method thereof

Abstract

The preparation method comprises the following steps: adding water, an emulsifier, a buffering agent, an activating agent, a diffusant, a vinyl nitrile monomer and an organic silicon monomer pre-emulsified by the emulsifier into a polymerization kettle, then replacing with nitrogen, and adding an initiator, the preparation method comprises the following steps: adding conjugated diene, a molecular regulator and a deoxidant, then adding an initiator to carry out polymerization reaction, when the conversion rate reaches 40-50%, supplementing an organosilicon monomer pre-emulsified by an emulsifier, when the conversion rate reaches 80-90%, adding a terminator, and then discharging; after discharging, degassing in a degassing tower, cooling, and then discharging to obtain butyronitrile silicone rubber latex; and adding the degassed butyronitrile silicone rubber latex into a coagulation kettle, adding an anti-aging agent and a coagulant, washing, and drying at low temperature to obtain the silicon-containing nitrile rubber. The preparation method can improve the thermal stability of the nitrile rubber.

Description

Technical Field

[0001] The invention relates to heat-resistant and low-temperature-resistant silicon copolymer modified nitrile rubber and a preparation method thereof, belonging to the technical field of modified nitrile rubber preparation. Background Art

[0002] Nitrile rubber (NBR) is the most representative synthetic rubber among nitrile rubbers, which is copolymerized by acrylonitrile and butadiene. It is a typical non-crystalline oil-resistant rubber. The most notable feature of NBR is that it contains nitrile groups in its molecular chain, which gives it good resistance to non-polar oils and low aromatic solvents. Due to its special performance advantages, NBR is widely used in the production of a variety of non-tire rubber products, such as hoses, tapes, seals, films, rubber rollers, coated fabrics, sheets, gloves, shoes, oil production packer components and other oil-resistant products. In addition, it is also used in aircraft fuel tanks that require high oil-resistant sealing performance. NBR and its modified material products are widely used in the automotive industry, aerospace, oilfield chemical industry, textile industry, wire and cable, and building materials.

[0003] Chinese patent CN 115043980 A discloses a method for preparing a silicon-containing thermoplastic elastomer using linear or cyclic siloxanes such as methyl disiloxane as functional monomers, specifically: styrene and part of the emulsifier, part or all of the regulator are added to a polymerization kettle, nitrogen pressure-vacuum replacement is used, conjugated diene is added, after stirring, part or all of the initiator is added, emulsion polymerization is carried out under stirring, and part of the emulsifier and part of the acrylonitrile are added to the polymerization kettle when the reaction conversion rate reaches 20-35%; in the late reaction period, when the conversion rate reaches 50-60%, a mixture of emulsifier, remaining regulator, remaining initiator, remaining acrylonitrile and a fourth monomer is added, and when the reaction conversion rate reaches 85-90%, a terminator is added to terminate the reaction. Flash degassing is performed, and after the reaction is completed, the resultant emulsion is mixed with the antioxidant emulsion, and then condensed, filtered, dehydrated, and dried in sequence. Since the organic silicon monomer used in this method is a linear or cyclic siloxane such as methyl disiloxane, the product is usually a core-shell structure, which has a certain limiting effect on its performance.

[0004] Chinese 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, add 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, add deoxidizer and 62-72.5 parts of butadiene, then add 0.02-0.25 parts of initiator to carry out polymerization reaction, when the polymerization conversion rate reaches 40%-75%, add acrylonitrile, initiator and molecular weight regulator once, when the conversion rate reaches 80%-84%, add terminator to cool and discharge, prepare carboxylated nitrile latex, after condensation, washing and drying, prepare carboxylated nitrile rubber product. However, when this method is applied to copolymerization of organosilicon monomers, a large amount of gel will be produced due to the hydrolysis and condensation of organosilicon monomers, resulting in limited product performance improvement.

[0005] Chinese patent CN 102464767 B discloses a method for in-situ preparation of silicone rubber composite materials. The preparation steps are: add water, emulsifier, monovinyl aromatic monomer and molecular weight regulator to the reactor in sequence, and then add organic silicon monomer containing carbon-carbon unsaturated bonds and conjugated diene under the protection of N2; start the polymerization kettle stirring, adjust the temperature of the reaction system in the polymerization kettle to the polymerization temperature, add initiator, start the reaction, the polymerization temperature is 5-30°C, the polymerization time is controlled at 7-12 hours, and when the total monomer conversion rate reaches 60-70%, add terminator to terminate the polymerization reaction; the latex is degassed, condensed and dried to obtain a solid product. The organic silicon monomer in this method has a side chain structure, and the improvement of the comprehensive performance of the material is limited.

[0006] Chinese patent CN 102020752 A discloses a method for in-situ hybrid grafting modification of polyconjugated diene latex, and the technical scheme adopted is (based on 100 parts of the dry rubber mass of the latex containing polyconjugated diene): 4 to 25 parts, preferably 10 to 15 parts, of an organosiloxane monomer containing an unsaturated bond are added to the latex containing polyconjugated diene, and the mixture is stirred and mixed evenly, and 0.20 to 0.36 parts of an initiator are added at a temperature of 5 to 85°C and under stirring conditions for grafting polymerization for 5 to 8 hours, and finally the grafted modified latex is condensed and dried. The content of the grafted silicon-containing group in this method is low, and it can only be grafted to the end of the molecular chain, and the effect produced is small; in addition, this method is to place the silicon-containing group in the side chain, which is essentially different from the method of placing the silicon-containing group in the main chain.

[0007] At the 2013 National Polymer Academic Paper Conference, "Special Polysiloxane Grafting Modification of Nitrile Rubber to Improve Its Low-Temperature Performance" used a mercaptomethyl end-capping agent and trifluoropropyl methylcyclotrisiloxane through cationic catalyzed ring-opening polymerization to synthesize mercaptomethyl end-capped fluoropropyl silicone oil, and then used the synthesized mercaptomethyl end-capped fluoropropyl silicone oil to modify nitrile rubber in a Haake torque rheometer. This method is difficult to produce molecular-level mixing, and has limited performance improvement. This method involves many process steps and has a high production cost.

[0008] "Organic silicon modified nitrile rubber and new silicone rubber vulcanization system" uses mercaptomethyl end-capping agent and trifluoropropyl methyl cyclotrisiloxane to synthesize mercaptomethyl end-capped fluoropropyl silicone oil through cationic catalysis ring-opening polymerization, and then uses the synthesized mercaptomethyl end-capped fluoropropyl silicone oil to modify nitrile rubber in a Haake torque rheometer. The modified nitrile rubber is then blended with fluorosilicone rubber. This method is a physical blending modification, which has a large difference in molecular distribution from copolymerization modification in terms of dispersibility.

[0009] Chinese patent CN1656153A discloses a high-performance nitrile rubber material and its preparation method, which relates to the field of rubber technology, using nitrile rubber, silicone rubber and carbon quantum dots as main raw materials, the particle size of the carbon quantum dots is 1-3nm; the weight ratio of the rubber to the silicone rubber and the carbon quantum dots is 50-80:20-50:0.5-10. This method is a physical blending modification, which is a completely different technical route from copolymerization. When the amount of functional fillers increases, phase separation will occur, which will have a negative impact on the comprehensive performance of the material.

[0010] The Second National Rubber Products Technology Seminar, "Study on SiO2-PMMA Hybrid Material Modified Nitrile Rubber" used sodium silicate as the silicon source, and after acidification, acrylic acid was added for organic treatment to form an acrylic acid intermediate containing active silanol gel. Methyl methacrylate (MMA) was added to the system, and an organic-inorganic hybrid material (SiO2-PMMA) containing silicon dioxide was synthesized by emulsion polymerization. SiO2-PMMA was used to blend and modify nitrile rubber. Although this method improves the mechanical properties of the copolymer, it has limited improvement in temperature resistance.

[0011] Chinese patent CN 113429701 B discloses a PVC / nitrile conveyor belt and its raw materials and preparation method, and specifically relates to a PVC / nitrile conveyor belt and its raw materials and preparation method. The raw materials for preparing the PVC / nitrile conveyor belt contain polyvinyl chloride, modified nitrile rubber, maleic anhydride grafted POE, polyetheretherketone particles, antioxidants and ultraviolet absorbers. The polyetheretherketone particles are stored independently, and the mass ratio of the modified nitrile rubber, maleic anhydride grafted POE, polyetheretherketone particles to polyvinyl chloride is (5-15): (2-10): (0.5-5): (60-80); the modified nitrile rubber is prepared by polymerizing acrylonitrile, butadiene and vinyl silane, and then coupling the obtained polymerization product with a mercaptosilane coupling agent. The nitrile rubber is polymerized by a solution method, and the molecular weight of the obtained polymer is small compared to emulsion polymerization. At the same time, the pollution generated during the polymerization process is relatively large.

[0012] In the global rubber industry, "organosilicon isocyanate modified synthetic rubber vulcanizate" uses organosilicon isocyanate (organosilicon isocyanate oligomer, blocked butylamine organosilicon isocyanate oligomer and organosilicon urethane isocyanate) as a modifier to blend and modify nitrile rubber. This method belongs to post-processing modification, and its distribution uniformity is still inferior to copolymerization modification. Summary of the invention

[0013] The purpose of the present invention is to provide a silicon copolymer modified nitrile rubber and a preparation method thereof. By adding a special silicone monomer pre-emulsified with an emulsifier during the polymerization stage of the nitrile rubber, a silicon-oxygen bond with a higher bond energy is introduced into the main chain of the nitrile rubber molecule, thereby improving the thermal stability of the nitrile rubber. At the same time, the polarity of the silicon-oxygen bond is utilized to shield the molecular structure of the nitrile rubber, thereby improving the weather resistance of the nitrile rubber. In addition, the silicon-oxygen bond in the molecular structure can also increase the elasticity of the nitrile rubber under low temperature conditions. The problem that the nitrile rubber cannot meet the use requirements in some fields due to its temperature resistance and weather resistance is solved. In terms of the preparation process, the comprehensive preparation technology such as pre-emulsifying the silicone before adding the material, adding a buffer, and adopting low-temperature emulsion polymerization and low-temperature drying processes is implemented to reduce the gel produced by the hydrolysis and cross-linking of the silicone monomer in the polymerization system, thereby solving the problem that the related products of the silicone modified nitrile rubber are difficult to process due to the excessively high gel content.

[0014] To achieve the above object, the present invention discloses a method for preparing silicon copolymer modified nitrile rubber, the preparation method comprising the following steps:

[0015] In a polymerization kettle, water, emulsifier, buffer, activator, dispersant, vinyl nitrile monomer, silicone monomer pre-emulsified with emulsifier are added, and then replaced with nitrogen, conjugated diene, molecular regulator, deoxidizer, and then initiator are added to carry out polymerization reaction, when the conversion rate reaches 40-50%, silicone monomer pre-emulsified with emulsifier is added, when the conversion rate reaches 80-90%, terminator is added, and then the material is discharged; after the material is discharged, it is degassed in a degassing tower, cooled, and then discharged to obtain nitrile silicone rubber latex; the degassed nitrile silicone rubber latex is added to a coagulation kettle, an antioxidant and a coagulant are added, washed, and then dried at low temperature to obtain silicon copolymer modified nitrile rubber;

[0016] The structure of the silicone copolymer modified nitrile rubber is as follows:

[0017]

[0018] Wherein x, y, z are the degrees of polymerization, each independently selected from an integer greater than 1; R1, R2 are the side groups of the silicon-containing monomer used, each independently selected from C1-C 20 of alkyl.

[0019] According to the present invention, before the polymerization reaction, based on 100 parts of the total weight of the monomers, the added amount of the conjugated diene is 40-80 parts, preferably 45-60 parts; the added amount of the vinyl nitrile monomer is 10-51 parts, preferably 30-45 parts; and the added amount of the organosilicon monomer pre-emulsified with an emulsifier is 0.1-25 parts, preferably 0.1-15 parts.

[0020] In the present invention, when the conversion rate reaches 40-50%, based on 100 parts of the total weight of the monomers, the additional amount of the organosilicon monomer pre-emulsified with the emulsifier is 0.1-25 parts, preferably 0.1-15 parts.

[0021] The emulsifier described in the present invention is potassium rosinate soap, oleic acid soap, fatty acid, disproportionated potassium rosinate, sodium fatty acid, C8-C 20 Sodium alkyl sulfate, C8-C 20 Sodium alkylbenzene sulfonate, C8-C 20 At least one of calcium salt of alkylbenzene sulfonate and polyoxyethylene ether is added in an amount of 1-10 parts, more preferably 1-4 parts, based on 100 parts of the total weight of the monomers. The emulsifier can be KOH, NaOH, or H2SO4 to adjust the pH.

[0022] The buffer of the present invention is selected from at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, ammonia water and ammonium bicarbonate, preferably sodium carbonate or sodium bicarbonate, and the added amount is 0.2-1.5 parts based on 100 parts of the total weight of the monomers.

[0023] The activator of the present invention comprises at least one of ferrous sulfate, tetrasodium EDTA and sodium ferric EDTA, and its dosage is the conventional dosage in the art, and the added amount is preferably 0.1-2 parts based on 100 parts of the total weight of the monomers.

[0024] The diffusing agent of the present invention is selected from at least one of sodium β-naphthalenesulfonate formaldehyde condensate and diffusing agent-N, preferably sodium β-naphthalenesulfonate formaldehyde condensate. The added amount is preferably 0.5-5 parts, more preferably 1-3 parts, based on 100 parts of the total weight of the monomers.

[0025] The conjugated diene of the present invention is selected from C4-C 12 At least one of the conjugated dienes is preferably butadiene or isoprene.

[0026] The vinyl nitrile monomer of the present invention is selected from at least one of acrylonitrile and methacrylonitrile, preferably acrylonitrile.

[0027] The organosilicon monomer described in the present invention is divinylsiloxane, preferably at least one of divinyldimethylsilane, vinyl mono-terminated dimethylpolysiloxane and tetramethyldivinyldisiloxane.

[0028] The molecular regulator of the present invention is selected from at least one of tert-dodecyl mercaptan and n-dodecyl mercaptan, preferably tert-dodecyl mercaptan, and the added amount is preferably 0.1-0.6 parts based on 100 parts of the total weight of the monomers.

[0029] The oxygen scavenger of the present invention is at least one selected from sodium dithionite, dimethyl ketoxime, isoascorbic acid, carbohydrazide, and N-isopropylhydroxylamine, preferably sodium dithionite, and the dosage is the conventional dosage in the art.

[0030] The initiator of the present invention is a redox initiator, and at least one of cumene hydroperoxide and dicumyl hydroperoxide can be selected. The added amount is preferably 0.05-0.8 parts based on 100 parts of the total weight of the monomers.

[0031] The terminator of the present invention is selected from at least one of NaNO2, hydroxylamine sulfate, diethylhydroxylamine, 2,5-pentylbutylbenzene, sodium thiocarbamate (sodium dimethyldithiocarbamate), sodium nitrite, actinium iron reagent, and p-aminoazobenzene, and the added amount is preferably 0.5-8 parts based on 100 parts of the total weight of the monomers.

[0032] The antioxidant of the present invention is at least one selected from tris(nonylphenyl)phosphite, diphenylamine derivatives, polybutylbisphenol, 2,6-di-tert-butyl-4-methylphenol, antioxidant ODA, 4020 and 4010NA, preferably diphenylamine derivatives.

[0033] The coagulant described in the present invention is at least one selected from CaCl2, Al2(SO4)3, NaCl, potassium chloride, alum and polyaluminium chloride.

[0034] The polymerization reaction temperature of the present invention is 0-30°C, preferably 2-10°C.

[0035] The degassing time of the present invention is 3-6 hours.

[0036] The total weight of the monomers described in the present invention refers to the total weight of the conjugated diene, the vinyl nitrile monomer, the organosilicon monomer pre-emulsified with an emulsifier added before the polymerization reaction, and the organosilicon monomer pre-emulsified with an emulsifier added when the conversion rate reaches 40-50%.

[0037] In the present invention, unless otherwise specified, "parts" refer to parts by weight.

[0038] The present invention also provides a silicon copolymer modified nitrile rubber, the structure of the silicon copolymer modified nitrile rubber is as follows:

[0039]

[0040] Wherein x, y, z are the degrees of polymerization, each independently selected from an integer greater than 1; R1, R2 are the side groups of the silicon-containing monomer used, each independently selected from C1-C 20 The alkyl group;

[0041] The silicon copolymer modified nitrile rubber raw rubber has 12-50% acrylonitrile, 0.5-40% silicon content, Mooney viscosity ML1+4 100°C: 30-95, and glass transition temperature ≤-60°C.

[0042] The preparation method of the present invention adopts an organosilicon monomer pre-emulsified with an emulsifier, and the bond energy of the silicon-oxygen bond is 422.5KJ / mol, which is much higher than the bond energy of the carbon-carbon bond of 344.4KJ / mol. The introduction of the silicon-oxygen bond into the main chain of the nitrile rubber molecule can maximize the thermal stability of the nitrile rubber. For example, the thermal weight loss equilibrium temperature of the product of the preferred technical solution is 447°C. The electronegativity difference between silicon and oxygen atoms is large, so the polarity of the silicon-oxygen bond is large, which plays a shielding role on the side chain organic group, thereby improving the oxidation stability. The main chain silicon-oxygen-silicon bond of polysiloxane has a long bond distance and a large bond angle, and the flexibility of the main chain of the molecule is very good, and there is still molecular chain segment movement at a relatively low temperature. The silicon-oxygen bond in the main chain can make the nitrile rubber have better elasticity at low temperatures. The glass transition temperature of the product of the preferred technical solution reaches -60°C. By comprehensively implementing processes such as pre-emulsification of silicone monomers, system pH stabilization control, low-temperature emulsion copolymerization and low-temperature drying, the hydrolysis and condensation of silicone monomers are inhibited, thereby reducing the gel content of the product, making the product easy to process while having the above-mentioned properties. DETAILED DESCRIPTION

[0043] 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.

[0044] Source of raw materials or equipment:

[0045] Butadiene, purity 99.5%, produced by Lanzhou Petrochemical Company Synthetic Rubber Plant;

[0046] Acrylonitrile, purity 99.5%, produced by the synthetic rubber plant of Lanzhou Petrochemical Company;

[0047] Isoprene, purity 99.3%, produced by Lanzhou Xinlan Petrochemical Co., Ltd.;

[0048] Silicone monomers, Aladdin, McLean.

[0049] Evaluation and analysis methods:

[0050] Mooney viscosity: Use Mooney viscometer (GT-7082S2) produced by High Speed ​​Rail Testing Instrument Company to test raw rubber according to GB / T1232.1-2016.

[0051] Bound acrylonitrile: Test the raw rubber using the Kjeldahl method according to SH / T 1157-2015.

[0052] Silicon-based building blocks: Nuclear magnetic resonance method.

[0053] Tensile strength, 300% elongation stress (MPa): Implementation standard GB / T528-2009.

[0054] Glass transition temperature: DMA was used to test the glass transition temperature (DMA test conditions: heating rate 5°C / min, frequency 10 Hz, temperature range -70 to 60°C).

[0055] Thermal decomposition temperature: refer to GB / T14837.2.

[0056] Example 1

[0057] In a 5L polymerization reactor, 2063g of water, 300g of a mixture of potassium rosin soap and fatty acids (emulsifier, purity 15%), 10g of sodium carbonate, 5g of a mixture of ferrous sulfate and sodium EDTA iron salt (purity 20%), 100g of diffusing agent-N (purity 15%), 351.76g of acrylonitrile monomer, 80g of tetramethyl divinyl disiloxane (pre-emulsified with 50g of emulsifier) ​​were added, and then nitrogen was replaced twice; butanediol was added and the mixture was stirred for 2 hours. 502.51g of olefins, 1g of tert-dodecyl mercaptan, 10g of dimethyl ketoxime, and then 10g of diisopropylbenzene peroxide (purity of 80%) were added to carry out polymerization reaction at 2°C. When the conversion rate reached 45%, 71.52g of tetramethyl divinyl disiloxane (pre-emulsified with 50g of emulsifier) ​​was added. When the conversion rate reached 88%, 75g of a mixture of diethylhydroxylamine and 2,5-pentylbutylbenzene (purity of 40%) was added to discharge the material. After discharging, the material was degassed in a degassing tower for 3 hours, and the temperature was lowered to 20°C before discharging to obtain nitrile silicone rubber latex. The degassed latex was pumped into a coagulation kettle, and a mixture of tris(nonylphenyl)phosphite and diphenylamine derivatives and CaCl2 were added. It was washed with water three times, and then dried at 30°C to obtain a silicon copolymer modified nitrile rubber. The material performance test is shown in Table 1.

[0058] Example 2

[0059] In a 5L polymerization kettle, 1854g of water, 433.33g of a mixture of potassium rosin soap and oleic acid methyl soap (emulsifier, purity 15%), 15g of sodium bicarbonate, 50g of a mixture of white cake and ferrous sulfate (purity 20%), 333.33g of sodium β-naphthalenesulfonate formaldehyde condensate (purity 15%), 402.1g of acrylonitrile monomer, 100g of tetramethyl divinyl disiloxane (pre-emulsified with 50g of emulsifier) ​​were added, and then nitrogen was replaced at both ends. times; add 452.6g of butadiene, 2g of n-dodecyl mercaptan, 2.27g of dimethyl ketoxime, and then add 1.13g of cumene peroxide (purity of 80%) to carry out polymerization reaction at 5°C. When the conversion rate reaches 50%, add 51.52g of tetramethyl divinyl disiloxane (pre-emulsified with 50g of emulsifier). When the conversion rate reaches 88%, add 75g of a mixture of diethylhydroxylamine and NaNO2 (purity of 40%) to discharge. After discharging, degas in a degassing tower for 4.5 hours, and discharge after the temperature is reduced to 20°C to obtain nitrile silicone rubber latex. The degassed latex is pumped into a coagulation kettle, and a mixture of polybutylbisphenol and 2,6-di-tert-butyl-4-methylphenol and Al2(SO4)3 are added. It is washed with water three times, and then dried at 40°C to obtain silicon copolymer modified nitrile rubber. The material performance test is shown in Table 1.

[0060] Example 3

[0061] In a 5L polymerization reactor, 2179g of water, 150g of a mixture of sodium fatty acid and disproportionated potassium rosin soap (emulsifier, purity 15%), 6.67g of ammonia water, 15g of a mixture of white cake, ferrous sulfate and tetrasodium EDTA (purity 20%), 266.67g of sodium β-naphthalenesulfonate formaldehyde condensate (purity 15%), 402.1g of acrylonitrile monomer, and 102.02g of divinyldimethylsilane (pre-emulsified with 25g of emulsifier) ​​were added, and then nitrogen was replaced at both ends. times; add 402.1g of butadiene, 4g of n-dodecyl mercaptan, 2g of a mixture of carbohydrazide and N-isopropylhydroxylamine, and then add 1.00g of cumene peroxide (purity of 80%) to carry out polymerization reaction at 15°C. When the conversion rate reaches 40%, add 100g of divinyldimethylsilane (pre-emulsified with 25g of emulsifier). When the conversion rate reaches 90%, add 100g of sodium nitrite, actinium iron reagent, and a mixture of p-aminoazobenzene (purity of 40%) to discharge. After discharging, degas in a degassing tower for 6 hours, and discharge after the temperature is reduced to 20°C to obtain nitrile silicone rubber latex. The degassed latex is pumped into a coagulation kettle, and a mixture of 2,6-di-tert-butyl-4-methylphenol and antioxidant ODA and polyaluminum chloride are added. It is washed with water three times and then dried at 50°C to obtain silicon copolymer modified nitrile rubber. The material performance test is shown in Table 1.

[0062] Example 4

[0063] In a 5L polymerization kettle, 1793g of water, 100g of a mixture of sodium tetradecyl sulfate, sodium dodecylbenzene sulfonate and sodium fatty acid (emulsifier, purity 15%), 12g of ammonium bicarbonate, 60g of a mixture of white slag, ferrous sulfate and sodium EDTA iron salt (purity 20%), 400g of sodium β-naphthalenesulfonate formaldehyde condensate (purity 15%), 301.51g of acrylonitrile monomer, 81.82g of vinyl mono-terminated dimethyl polysiloxane (pre-emulsified with 20g of emulsifier) ​​were added. ) and then replaced with nitrogen twice; 723.62g of butadiene, 2.4g of tert-dodecyl mercaptan, 2.73g of dimethyl ketoxime, and then 1.35g of cumene peroxide (purity of 80%) were added to carry out polymerization reaction at 15°C. When the conversion rate reached 48%, 100g of vinyl mono-terminated dimethyl polysiloxane (pre-emulsified with 40g of emulsifier) ​​was added. When the conversion rate reached 89%, 90g of sodium nitrite and diethylhydroxylamine mixture (purity of 40%) were added to discharge. After discharging, the material was degassed in a degassing tower for 5 hours, and the material was discharged after the temperature was reduced to 20°C to obtain nitrile silicone rubber latex. The degassed latex was pumped into a coagulation kettle, and a mixture of tris(nonylphenyl)phosphite and antioxidant ODA and alum were added. It was washed with water three times, and then dried at 45°C to obtain silicon copolymer modified nitrile rubber. The material performance test is shown in Table 1.

[0064] Example 5

[0065] In a 5L polymerizer, 1485.88g of water, 546.67g of a mixture of fatty acid and calcium dodecylbenzenesulfonate (emulsifier, purity 15%), 13g of sodium carbonate, 100g of a mixture of white slag, ferrous sulfate and tetrasodium EDTA (purity 20%), 35g of diffusing agent-N (purity 15%), 351.76g of acrylonitrile monomer, and 50g of vinyl mono-terminated dimethyl polysiloxane (pre-emulsified with 20g of emulsifier) ​​were added, followed by nitrogen replacement twice; Add 402.01g of butadiene, 3g of tert-dodecyl mercaptan, 2g of sodium dithionite, and then add 0.63g of isopropyl peroxide (purity of 80%) to carry out polymerization reaction at 30°C. When the conversion rate reaches 40%, emulsify 202.53g of vinyl mono-terminated dimethyl polysiloxane with 100g of emulsifier and continuously drop it into the reactor. When the conversion rate reaches 85%, add 200g of sodium nitrite and diethylhydroxylamine mixture (purity of 40%) to discharge. After discharging, degas in a degassing tower for 4 hours, and discharge after the temperature is reduced to 20°C to obtain nitrile silicone rubber latex. The degassed latex is pumped into a coagulation reactor, 4020 and CaCl2 are added, washed with water three times, and then dried at 45°C to obtain silicon copolymer modified nitrile rubber. The material performance test is shown in Table 1.

[0066] Example 6

[0067] In a 5L polymerization reactor, 2251.44g of water, 100.33g of a mixture of fatty acid and dodecylbenzene sulfonate (emulsifier, purity 15%), 15g of sodium bicarbonate, 50g of a mixture of white slag, ferrous sulfate and EDTA tetrasodium salt (purity 20%), 266.67g of diffusant-N (purity 15%), 201.01g of acrylonitrile monomer, 20g of tetramethyl divinyl disiloxane (pre-emulsified with 20g of emulsifier) ​​were added, and then nitrogen Replace twice; add 703.52g of butadiene, 6g of tert-dodecyl mercaptan, 2.27g of sodium dithionite, and then add 1.13g of cumene peroxide (purity of 80%) to carry out polymerization reaction at 25°C. When the conversion rate reaches 48%, add 81.01 of tetramethyl divinyl disiloxane (pre-emulsified with 13g of emulsifier). When the conversion rate reaches 87%, add 125g of sodium nitrite and diethylhydroxylamine mixture (purity of 40%) to discharge. After discharging, degas in the degassing tower for 5.5 hours, and discharge after the temperature is reduced to 20°C to obtain nitrile silicone rubber latex. The degassed latex is pumped into a coagulation kettle, 4010NA and NaCl are added, washed with water three times, and then squeezed, dehydrated and dried to obtain silicon copolymer modified nitrile rubber. The material performance test is shown in Table 1.

[0068] Table 1

[0069]

[0070]

[0071] Comparative Example 1

[0072] The difference from Example 1 is that the organic silicon monomer pre-emulsified with an emulsifier is not added, and the other implementation conditions are the same. Since the molecular structure of the obtained nitrile rubber does not have a silicon-oxygen bond with a higher bond energy, its heat resistance and cold resistance are reduced.

[0073] In a 5L polymerization kettle, 2063g of water, 300g of a mixture of potassium rosin soap and fatty acid (emulsifier, purity 15%), 10g of sodium carbonate, 5g of a mixture of ferrous sulfate and sodium EDTA iron salt (purity 20%), 100g of diffusant-N (purity 15%), and 351.76g of acrylonitrile monomer were added, and then nitrogen replacement was performed twice; 653.27g of butadiene, 1g of tert-dodecyl mercaptan, 10g of dimethyl ketoxime, and then 10g of diisopropylbenzene peroxide (purity 80%) were added to carry out polymerization reaction at 2°C. When the conversion rate reached 88%, 75g of a mixture of diethylhydroxylamine and 2,5-pentylbutylbenzene was added to discharge the material. After discharging, the material was degassed in a degassing tower for 3 hours, and the temperature was reduced to 20°C before discharging to obtain nitrile rubber latex. The degassed latex was pumped into a coagulation kettle, and a mixture of tris(nonylphenyl)phosphite and diphenylamine derivatives and CaCl2 were added, washed with water three times, and then dried at 30°C to obtain nitrile rubber. The material performance test is shown in Table 2.

[0074] Comparative Example 2

[0075] The difference from Example 1 is that the pre-emulsified tetramethyl divinyl disiloxane is replaced with monovinyl siloxane, and the other implementation conditions are the same. The monovinyl silicon-containing monomer on the side chain of the nitrile rubber molecular chain can improve its heat resistance, but its effect of reducing the glass transition temperature is not obvious.

[0076] In a 5L polymerization kettle, 2063g of water, 300g of a mixture of potassium rosin soap and fatty acids (emulsifier, purity 15%), 10g of sodium carbonate, 5g of a mixture of ferrous sulfate and sodium EDTA iron salt (purity 20%), 100g of diffusing agent-N (purity 15%), 351.76g of acrylonitrile monomer, and 80g of monovinyl siloxane (pre-emulsified with 50g of emulsifier) ​​were added, and then nitrogen was replaced twice; butanediol was added and the mixture was stirred for 2 hours. 502.51g of olefins, 1g of tert-dodecyl mercaptan, 10g of dimethyl ketoxime, and then 10g of diisopropylbenzene peroxide (purity of 80%) were added to carry out polymerization reaction at 2°C. When the conversion rate reached 45%, 71.52g of monovinylsiloxane (pre-emulsified with 50g of emulsifier) ​​was added. When the conversion rate reached 88%, 75g of a mixture of diethylhydroxylamine and 2,5-pentylbutylbenzene (purity of 40%) was added to discharge the material. After discharging, the material was degassed in a degassing tower for 3 hours, and the temperature was lowered to 20°C before discharging to obtain nitrile silicone rubber latex. The degassed latex was pumped into a coagulation kettle, and a mixture of tris(nonylphenyl)phosphite and diphenylamine derivatives and CaCl2 were added. It was washed with water three times, and then dried at 30°C to obtain silicon copolymer modified nitrile rubber. The material performance test is shown in Table 2.

[0077] Comparative Example 3

[0078] The conditions are basically the same as those in Example 1, except that the reaction is terminated when the conversion rate reaches 92%. As the conversion rate increases, the gel content in the system increases, making the reaction system unstable, and the Mooney viscosity of the obtained material increases significantly. The mechanical properties decrease.

[0079] In a 5L polymerization reactor, 2063g of water, 300g of a mixture of potassium rosin soap and fatty acids (emulsifier, purity 15%), 10g of sodium carbonate, 5g of a mixture of ferrous sulfate and sodium EDTA iron salt (purity 20%), 100g of diffusing agent-N (purity 15%), 351.76g of acrylonitrile monomer, 80g of tetramethyl divinyl disiloxane (pre-emulsified with 50g of emulsifier) ​​were added, and then nitrogen was replaced twice; butanediol was added and the mixture was stirred for 2 hours. 502.51g of olefins, 1g of tert-dodecyl mercaptan, 10g of dimethyl ketoxime, and then 10g of diisopropylbenzene peroxide (purity of 80%) were added to carry out polymerization reaction at 2°C. When the conversion rate reached 45%, 71.52g of tetramethyl divinyl disiloxane (pre-emulsified with 50g of emulsifier) ​​was added. When the conversion rate reached 92%, 75g of a mixture of diethylhydroxylamine and 2,5-pentylbutylbenzene (purity of 40%) was added to discharge the material. After discharging, the material was degassed in a degassing tower for 3 hours, and the material was discharged after the temperature was reduced to 20°C to obtain nitrile silicone rubber latex. The degassed latex was pumped into a coagulation kettle, and a mixture of tris(nonylphenyl)phosphite and diphenylamine derivatives and CaCl2 were added. It was washed with water three times, and then dried at 30°C to obtain silicon copolymer modified nitrile rubber. The material performance test is shown in Table 2.

[0080] Comparative Example 4

[0081] The conditions were basically the same as those in Example 1, except that tetramethyldivinyldisiloxane was directly added into the reaction kettle at once without pre-emulsification.

[0082] In a 5L polymerization kettle, 2063g of water, 400g of a mixture of potassium rosin soap and fatty acid (emulsifier, purity 15%), 10g of sodium carbonate, 5g of a mixture of ferrous sulfate and sodium EDTA iron salt (purity 20%), 100g of diffusant-N (purity 15%), 351.76g of acrylonitrile monomer, and 80g of tetramethyl divinyl disiloxane were added, and then nitrogen was replaced twice; 502.51g of butadiene, 1g of tert-dodecyl mercaptan, 10g of dimethyl ketoxime, and then 10g of diisopropylbenzene peroxide (purity 80%) were added to carry out polymerization reaction at 2°C. When the conversion rate reached 45%, 71.52g of tetramethyl divinyl disiloxane was added. When the conversion rate reached 88%, 75g of a mixture of diethylhydroxylamine and 2,5-pentylbutylbenzene (purity 40%) was added to discharge. After the material is discharged, it is degassed in a degassing tower for 3 hours, and the temperature is lowered to 20°C before the material is discharged to obtain nitrile silicone rubber latex. The degassed latex is pumped into a coagulation kettle, and a mixture of tris(nonylphenyl)phosphite and diphenylamine derivatives and CaCl2 are added. It is washed with water three times and then dried at 30°C to obtain silicon copolymer modified nitrile rubber. The material performance test is shown in Table 2.

[0083] Comparative Example 5

[0084] The conditions are basically the same as those in Example 1, except that no buffer is added.

[0085] In a 5L polymerization reactor, 2063g of water, 300g of a mixture of potassium rosin soap and fatty acids (emulsifier, purity 15%), 5g of a mixture of ferrous sulfate and sodium EDTA iron salt (purity 20%), 100g of diffusing agent-N (purity 15%), 351.76g of acrylonitrile monomer, 80g of tetramethyl divinyl disiloxane (pre-emulsified with 50g of emulsifier) ​​were added, and then nitrogen was replaced twice; 50g of butadiene was added. 2.51g, 1g of tert-dodecyl mercaptan, 10g of dimethyl ketoxime, and then add 10g of diisopropylbenzene peroxide (purity of 80%) to carry out polymerization reaction at 2°C. When the conversion rate reaches 45%, add 71.52g of tetramethyl divinyl disiloxane (pre-emulsified with 50g of emulsifier). When the conversion rate reaches 88%, add 75g of a mixture of diethylhydroxylamine and 2,5-pentylbutylbenzene (purity of 40%) to discharge. After discharging, degas in a degassing tower for 3 hours, and discharge after the temperature is reduced to 20°C to obtain nitrile silicone rubber latex. The degassed latex is pumped into a coagulation kettle, and a mixture of tris(nonylphenyl)phosphite and diphenylamine derivatives and CaCl2 are added. It is washed with water three times, and then dried at 30°C to obtain silicon copolymer modified nitrile rubber. The material performance test is shown in Table 2.

[0086] Table 2

[0087]

[0088]

[0089] 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 silicon copolymer modified nitrile rubber, characterized in that: The following steps are involved: In a polymerization kettle, water, emulsifier, buffer, activator, dispersant, vinyl nitrile monomer, silicone monomer pre-emulsified with emulsifier are added, and then replaced with nitrogen, conjugated diene, molecular regulator, deoxidizer, and then initiator are added to carry out polymerization reaction, when the conversion rate reaches 40-50%, silicone monomer pre-emulsified with emulsifier is added, when the conversion rate reaches 80-90%, terminator is added, and then the material is discharged; after the material is discharged, it is degassed in a degassing tower, cooled, and then discharged to obtain nitrile silicone rubber latex; the degassed nitrile silicone rubber latex is added to a coagulation kettle, an antioxidant and a coagulant are added, washed, and then dried at low temperature to obtain silicon copolymer modified nitrile rubber; The structure of the silicone copolymer modified nitrile rubber is as follows: Wherein x, y, z are the degrees of polymerization, each independently selected from an integer greater than 1; R1, R2 are the side groups of the silicon-containing monomer used, each independently selected from C1-C 20 of alkyl.

2. The preparation method according to claim 1, characterized in that: Before the polymerization reaction, based on 100 parts of the total weight of the monomers, the added amount of the conjugated diene is 40-80 parts; the added amount of the vinyl nitrile monomer is 10-51 parts; The amount of the organic silicon monomer pre-emulsified with the emulsifier added is 0.1-25 parts.

3. The preparation method according to claim 1, characterized in that: When the conversion rate reaches 40-50%, the amount of the additional organosilicon monomer pre-emulsified with the emulsifier is 5-25 parts based on 100 parts of the total weight of the monomers.

4. The preparation method according to claim 1, characterized in that: The emulsifier is potassium rosinate soap, oleic acid soap, fatty acid, disproportionated potassium rosinate, sodium fatty acid, C8-C 20 Sodium alkyl sulfate, C8-C 20 Sodium alkylbenzene sulfonate, C8-C 20 At least one of calcium salt of alkylbenzene sulfonate and polyoxyethylene ether is added in an amount of 1 to 10 parts based on 100 parts of the total weight of the monomers.

5. The preparation method according to claim 1, characterized in that: The buffer is selected from at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, ammonia water and ammonium bicarbonate, and the added amount is 0.2-1.5 parts based on 100 parts of the total weight of the monomers.

6. The preparation method according to claim 1, characterized in that: The activator comprises at least one of ferrous sulfate, tetrasodium EDTA and sodium ferric EDTA, and the added amount is 0.1-2 parts based on 100 parts of the total weight of the monomers.

7. The preparation method according to claim 1, characterized in that: The diffusing agent is selected from at least one of β-sodium naphthalenesulfonate formaldehyde condensate and diffusing agent-N, and the added amount is 0.5-5 parts based on 100 parts of the total weight of the monomers.

8. The preparation method according to claim 1, characterized in that: The conjugated diene is selected from C4-C 12 At least one of the conjugated dienes.

9. The preparation method according to claim 1, characterized in that: The vinyl nitrile monomer is selected from at least one of acrylonitrile and methacrylonitrile.

10. The preparation method according to claim 1, characterized in that: The organosilicon monomer is selected from at least one of divinyldimethylsilane, vinyl mono-terminated dimethylpolysiloxane and tetramethyldivinyldisiloxane.

11. The preparation method according to claim 1, characterized in that: The molecular regulator is selected from at least one of tert-dodecyl mercaptan and n-dodecyl mercaptan, and the added amount is 0.1-0.6 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, carbohydrazide and N-isopropylhydroxylamine.

13. The preparation method according to claim 1, characterized in that: The initiator is selected from at least one of cumene hydroperoxide and dicumyl hydroperoxide, and the added amount is 0.05-0.8 parts based on 100 parts of the total weight of the monomers.

14. The preparation method according to claim 1, characterized in that: The terminator is selected from at least one of NaNO2, hydroxylamine sulfate, diethylhydroxylamine, 2,5-pentylbutylbenzene, sodium thiocarbamate (sodium dimethyldithiocarbamate), sodium nitrite, actinium iron reagent, and p-aminoazobenzene, and the added amount is 0.5-8 parts based on 100 parts of the total weight of the monomers.

15. The preparation method according to claim 1, characterized in that: The antioxidant is selected from at least one of tris(nonylphenyl)phosphite, diphenylamine derivatives, polybutylbisphenol, 2,6-di-tert-butyl-4-methylphenol, antioxidant ODA, 4020 and 4010NA.

16. The preparation method according to claim 1, characterized in that: The coagulant is selected from at least one of CaCl2, Al2(SO4)3, NaCl, potassium chloride, alum and polyaluminium chloride.

17. The preparation method according to claim 1, characterized in that: The polymerization temperature is 0-30°C.

18. A silicon copolymer modified nitrile rubber, characterized in that: The structure of the silicone copolymer modified nitrile rubber is as follows: Wherein x, y, z are the degrees of polymerization, each independently selected from an integer greater than 1; R1, R2 are the side groups of the silicon-containing monomer used, each independently selected from C1-C 20 The alkyl group; The silicon copolymer modified nitrile rubber raw rubber has 12-50% acrylonitrile, 0.5-40% silicon content, Mooney viscosity ML1+4 100°C: 30-95, and glass transition temperature ≤-60°C.

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