A hydrogenated random copolymer of butadiene-isoprene rubber and a method for preparing the same

Abstract

The application discloses a hydrogenated random copolymer butadiene-isoprene rubber and a preparation method thereof. After a polymerization solution system containing a structure regulator is heated to a temperature required for initiating polymerization, mixed monomers containing butadiene and isoprene, a branching agent and an initiator are continuously and uniformly added, a polymerization reaction is initiated and carried out, a polymer glue solution is obtained, and the polymer glue solution is subjected to activation and catalytic hydrogenation reaction, so that the EBPR with wide distribution and good processing performance is obtained. The vulcanized rubber of the EBPR has high tensile strength, low deformation and excellent anti-aging performance, and has wide application.

Description

Technical Field

[0001] This invention relates to a hydrogenated random copolymer butadiene-isoprene rubber, and more particularly to a rubber with a wide molecular weight distribution and a random distribution of molecular chains containing polyethylene, polybutene, polypropylene, polyisopropylene and other chain segments. It also relates to its preparation method and belongs to the field of synthetic rubber technology. Background Technology

[0002] Existing ethylene propylene diene monomer (EPDM) rubber contains 1.4–5.0% (mol) of unsaturation. The vulcanizate exhibits excellent ozone resistance, heat resistance, weather resistance, and aging resistance, and is widely used in automobiles and sealing components, waterproof materials, wires and cables, heat-resistant hoses, and tapes. EPDM is synthesized from ethylene, propylene, and a small amount of diene hydrocarbons using a vanadium-aluminum catalyst. Due to differences in monomer concentration and the concentration of monomers directly contacting the active sites, as well as variations in the polymerization rates between monomers, the compositional distribution in the synthesized polymer molecules is uneven. Typically, the ethylene content in EPDM molecules ranges from 45% to 70%. EPDM with different amounts of ethylene units has different applications and directions. For example, copolymers containing 70% or higher ethylene units have higher elongation in their vulcanizates, longer ethylene unit sequences, and poorer relaxation properties. The longer block ethylene units are prone to crystallization, acting as nodes for lateral physical bonds. The presence of a microcrystalline phase in the polymer, while increasing tensile strength, also increases tensile deformation. Existing EPDM synthesis technologies struggle to achieve uniform alternating copolymerization of ethylene, propylene, and small amounts of diene monomers, thus reducing the polymer's crystallization tendency. Furthermore, commercially available EPDM exhibits Mooney viscosities ranging from 18 to 90; the main chain is a saturated linear chain, while the iodine value of the side chains ranges from 6 to 30 g / 100g.

[0003] Partial hydrogenation of 1,2-addition polybutadiene rubber can easily yield polymers containing polyethylene and polybutene segments. Currently, no such hydrides have been reported. Such derivative polymers are common lithium-based polymers and hydrogenated polystyrene-B-conjugated diene hydrides such as SEBS or SEPS. The iodine value of these polymers is 1-10 g / 100 g. Due to their narrow molecular weight distribution, they cannot be vulcanized with sulfur and exhibit the behavior of thermoplastic elastomers.

[0004] Existing nickel-based and rare-earth-catalyzed conjugated dienes are all high-cis rubbers, with a 1,4-addition unit content >95%. The polymerization solution contains catalyst residues, which can poison the active lithium-titanium catalyst. Furthermore, after hydrogenation, the high-cis conjugated diene rubber exhibits long polyvinyl groups in its molecular chain, and the hydrides crystallize, demonstrating high-modulus plastic behavior.

[0005] Chinese patent (CN1884328A) relates to a method for preparing branched high-vinyl polybutadiene rubber using molybdenum-based catalysis, and Chinese patent (CN105199028A) discloses a high-vinyl polybutadiene rubber with adjustable microstructure and its preparation method. However, the polymers prepared by the above techniques are not easily hydrogenated. Meanwhile, a high-vinyl polybutadiene oil-extended rubber and its preparation method are disclosed in (“High-vinyl polybutadiene oil-extended rubber and its preparation method,” Rubber Technology, April 2013), and a molecular design of star-shaped vinyl polybutadiene rubber is disclosed in (“Molecular design of star-shaped vinyl polybutadiene rubber,” Proceedings of the 2004 International Rubber Conference (A)). All of these techniques belong to Ziegler-Natta improved coordination polymerization, and none have reported on the hydrogenation of their polymers. Chinese patent (CN102863576A) discloses a composite structure modifier suitable for preparing 3,4-isoprene rubber and a method for preparing 3,4-isoprene rubber. Specifically, it describes a composite structure modifier suitable for preparing 3,4-isoprene rubber and a method for preparing 3,4-isoprene rubber. At higher polymerization temperatures, it can efficiently adjust the 3,4-structure content of the polymer, resulting in a 3,4-structure content of over 70% in the obtained product. When these polymers are used in automotive tire tread compounds, they give the tread good wet grip and low rolling resistance. However, the aforementioned patent does not describe the hydrogenation of its polymers. Furthermore, hydrogenated products of lithium-based polystyrene-isoprene copolymers, such as SEP produced by KRATON, involve fully hydrogenated double bonds in the molecule. These SEPs can only be used as oil thickeners because they do not contain double bonds in their molecules and therefore cannot be vulcanized, failing to exhibit rubber-like behavior.

[0006] In summary, EPDM and existing anionic polystyrene-conjugated diene hydrides such as SEBS, SEPS, and SEP are all thermoplastic elastomers, not vulcanized rubbers. However, no related technologies have been reported for the preparation of hydrides of anionic diene copolymers. Summary of the Invention

[0007] The existing coordination polymerization-prepared polybutadiene rubber cannot be selectively hydrogenated, and the existing EPDM rubber synthesis is difficult to form uniform alternating chains of ethylene, propylene and a small amount of diene monomers, resulting in technical defects such as microcrystalline phases in the polymer molecular chain and high tensile deformation.

[0008] The primary objective of this invention is to provide a hydrogenated random copolymer butadiene-isoprene rubber (EBDP) with a wide molecular weight distribution, easy processing and molding, and anti-aging properties, the vulcanizate of which has high tensile strength, low deformation, and excellent anti-aging properties.

[0009] The second objective of this invention is to provide a simple and low-cost method for preparing EBDP. This method first synthesizes polybutadiene-isoprene rubber (BIR) with a side alkenyl content of 30-55% via anionic polymerization, and then selectively hydrogenates it to obtain hydrogenated random copolymer butadiene-isoprene rubber EBDP with a polyethylene-butene-propylene-isopropylene structure. In this method, butadiene and isoprene monomers can be completely converted, the polymerization reaction time is short, and various technical deficiencies and drawbacks existing in the current EPDM preparation process are avoided.

[0010] To achieve the above technical objectives, the present invention provides a hydrogenated random copolymer butadiene-isoprene rubber having the structure of Formula 1:

[0011]

[0012] Where x, y, z, m, n, o, p, and q represent the degree of polymerization; R represents the branching unit; (n+o+p+q) / (x+y+z+m) = 20–26; (y+z) / (x+m) = 17.5–45; (y+m+n+o) / (x+p+z+q) = 0.12–0.16. x, y, z, m, n, o, p, and q are all integers greater than or equal to 0, and y, m, n, and o are not simultaneously 0, nor are x, p, z, and q simultaneously 0. R can be a unit introduced by the branching agent divinylbenzene or 1,3,5-hextriene.

[0013] The EBDP main chain of this invention contains only trace amounts of double bonds, while the majority of polyethylene and saturated alkyl groups have a structure similar to saturated hydrocarbons with the polyolefin chain. Therefore, EBDP and polyolefins have good compatibility and do not undergo phase separation. At the same time, the trace amounts of double bonds on the EBDP main chain and the relatively large amount of double bonds on the side chains can form a network-like macromolecule through vulcanization. Even if a small number of uncrosslinked double bonds exist in the vulcanized rubber, they will not be completely on the main chain during the later crosslinking aging process, ensuring that the polymer or composite material has excellent anti-aging behavior.

[0014] The EBDP of the present invention has a suitable and uniformly distributed side alkyl content, which reduces its crystallization and deformation, increases its elasticity, and can achieve good comprehensive physical properties and processing performance when compounded with polyolefins.

[0015] The polymer units in the EBDP of the present invention exhibit a random distribution, which can effectively reduce the crystallinity of the polymer, giving it characteristics such as low crystallinity and low deformation.

[0016] As a preferred embodiment, the degree of unsaturation of the hydrogenated random copolymer butadiene-isoprene rubber by iodine value method is 3.0-4.5% (mol). The proportion of unsaturation on the main chain of the hydrogenated random copolymer butadiene-isoprene rubber is 0.10-0.20% (mol) (main chain unsaturation number / total unsaturation number).

[0017] As a preferred embodiment, the total mass percentage of butadiene 1,2 structural units and isoprene 3,4 structural units in the original hydrogenated random copolymer butadiene-isoprene rubber before hydrogenation is 25-60%, more preferably 30-55%.

[0018] As a preferred option, R is phenyl or alkylene.

[0019] As a preferred embodiment, the Mooney viscosity ML of the hydrogenated random copolymer butadiene-isoprene rubber is... 125 °C = 65–85, Molecular weight distribution index M w / M n If the value is greater than 1.8, the crystallinity is less than 3.

[0020] This invention also provides a method for preparing hydrogenated random copolymer butadiene-isoprene rubber. The method involves heating a polymerization solution system containing a structure modifier to the temperature required for initiating polymerization, then continuously and uniformly adding a mixed monomer including butadiene and isoprene, a branching agent, and an initiator to initiate and carry out a polymerization reaction to obtain a polymer solution. The polymer solution is then activated and subjected to a catalytic hydrogenation reaction to obtain the final product.

[0021] As a preferred embodiment, the concentration of the structure modifier in the polymerization solution system is 150–250 mg / kg solvent. As a more preferred embodiment, the structure modifier includes at least one of tetrahydrofurfuryl ether, bis(tetrahydrofurfuryl propane), tetrahydrofurfuryl butyl ether, and tetrahydrofurfuryl ethyl ether. The solvent is a conventional hydrocarbon solvent, specifically cyclohexane. Selecting appropriate structure modifiers and dosages can effectively adjust the 1,2 polymerization ratio of butadiene and the 3,4 polymerization ratio of isoprene, thereby effectively adjusting the content of side alkyl and side alkenyl groups in the hydrogenated random copolymer butadiene-isoprene rubber.

[0022] As a preferred embodiment, the weight ratio of isoprene to butadiene is 0.15–0.20. The mass percentage of isoprene should not be too high or too low. If the amount of isoprene is too high, the unsaturation degree of the polyisoprene unit in the subsequent polymer hydrogenation will be too high, and the physical properties of the polymer will decrease, mainly in terms of anti-aging and filling capacity for oils and inorganic fillers. If the amount of isoprene is too low, the content of introduced side alkenyl groups will be too low, reducing the degree of vulcanization crosslinking and the performance of vulcanized rubber.

[0023] As a preferred embodiment, the branching agent comprises 1,3,5-hextriene and / or divinylbenzene. When 1,3,5-hextriene is chosen as the branching agent, it only exhibits branching activity during 1,2-addition, while in the polymerization reaction system of this invention, the 1,2-addition probability is 30-55%; 1,3,5-hextriene does not produce branched chains during 1,4-addition, only short side olefin units. In anionic polymerization, branching occurs simultaneously with chain growth, thereby increasing the weight-average molecular weight of the polymer and broadening its molecular weight distribution index.

[0024] As a preferred embodiment, the mass of the branching agent is 0.03 to 0.05% of the mass of the mixed monomers. Too much branching agent is undesirable, as it can easily lead to the formation of large molecular weight gels. Conversely, too little branching agent makes it difficult to achieve the goal of broadening the molecular weight distribution.

[0025] As a preferred embodiment, the mixed monomers may further include isoprene.

[0026] As a preferred approach, the mixed monomers, branching agents, and initiators are continuously and uniformly added to the polymerization solution system over a period of 40–50 minutes. By controlling the uniform and continuous addition of the mixed monomers, branching agents, and initiators, the high degree of random copolymerization of the polymer can be effectively controlled, thereby adjusting the uniform distribution of side vinyl and side isopropylene groups in EBDP and improving the vulcanization effect of EBDP.

[0027] As a preferred option, the temperature required to initiate the polymerization reaction is 50-55℃, and the maximum temperature during the polymerization reaction does not exceed 75℃.

[0028] As a preferred embodiment, the activation and catalytic hydrogenation reaction process includes the following steps: 1) adding alkyllithium and activating for 10-15 min at a temperature of 65-80°C and a hydrogen pressure of not less than 10 bar; 2) adding a portion of the co-catalyst and activating for 10-15 min at a temperature of 65-80°C and a hydrogen pressure of not less than 10 bar; 3) adding a portion of the main catalyst and hydrogenating for 40-60 min at a temperature of 70-120°C and a hydrogen pressure of 13-16 bar; 4) adding a portion of the co-catalyst and hydrogenating for 40-60 min at a temperature of 70-120°C and a hydrogen pressure of 13-16 bar; 5) simultaneously adding the remaining portion of the main catalyst and co-catalyst and hydrogenating for 40-60 min at a temperature of 70-120°C and a hydrogen pressure of 13-16 bar.

[0029] As a preferred embodiment, the amount of alkyl lithium added is 12 to 18 times the total molar amount of the cocatalyst.

[0030] As a preferred embodiment, the co-catalyst is dimethyl phthalate and / or methyl o-methylbenzoate.

[0031] As a preferred embodiment, the total amount of the co-catalyst added is 1 / 6 to 1 / 8 of the total molar amount of the main catalyst.

[0032] As a preferred embodiment, the amount of co-catalyst added in steps 2), 4), and 5) accounts for 28-38%, 28-38%, and 28-38% of the total molar amount of co-catalyst, respectively.

[0033] As a preferred embodiment, the main catalyst is dicyclopentadiene titanium dichloride.

[0034] As a preferred embodiment, the total amount of the main catalyst added is 0.12 to 0.15 g / 100 g polymer.

[0035] As a preferred embodiment, the amount of main catalyst added in steps 3) and 5) accounts for 60-80% and 20-40% of the total molar amount of the main catalyst, respectively.

[0036] This invention selects a dicyclopentadiene titanium dichloride catalytic system, which achieves a hydrogenation rate of over 99% for the double bonds in butadiene polymerization units. However, for isoprene polymerization units, the double bonds are difficult to hydrogenate due to the steric hindrance effect of the methyl groups on the side methyl groups and isopropenyl groups in the molecule. The double bonds on the main chain are more easily hydrogenated by the double bonds on the isopropenyl side chains. The goal of this invention is to hydrogenate as many double bonds as possible on the main chain while retaining the double bonds on the side chains. The double bonds on the side chains provide crosslinking points for subsequent vulcanization applications. Fewer double bonds on the main chain and a relatively larger number of double bonds on the side chains are beneficial to the anti-aging properties of the vulcanized rubber. The dicyclopentadiene titanium dichloride catalytic system can achieve the desired selective hydrogenation effect. Furthermore, the reason for adding the main and co-catalysts to the hydrogenation system in multiple stages for catalytic hydrogenation is that the catalytic hydrogenation of this invention is an active complex catalysis. The catalyst has high activity in the early stage and can complete 85% hydrogenation of the polybutadiene unit, but the activity decreases rapidly in the later stage. Therefore, the purpose of adding catalyst in the later stage is to regenerate or establish new catalytic active centers to hydrogenate as much of the polybutadiene unit and the 1,4-addition polymerization unit of isoprene as possible, thereby preserving as much of the side isopropene functional group generated by the 3,4-addition of isoprene as possible.

[0037] The EBDP rubber of this invention can be vulcanized using a conventional vulcanizing compound formulation. A specific vulcanizing compound formulation is as follows (parts by weight): 100 parts EBDP, 25 parts softening filler oil, 60 parts carbon black, 1.5 parts accelerator T, and 1.5 parts sulfur. The vulcanizing compound is mixed and vulcanized according to national standards, and the vulcanization conditions are: 160℃ / 20min.

[0038] Compared with existing technologies, the beneficial effects of the technical solution of this invention are as follows:

[0039] In the preparation process of EBDP of the present invention, the polymerization time of its prepolymer BIR is short and the molecular weight distribution is controllable. It can be prepared using existing anionic polymerization processes, which is beneficial for industrial production.

[0040] In the preparation process of EBDP of the present invention, it is easy to adjust the amount of isoprene monomer and use a special titanium-based catalytic system to hydrogenate it, thereby controlling the content of side vinyl groups in EBDP. The titanium-based catalytic system can selectively hydrogenate the double bonds on the main chain to the maximum extent, while the isopropylene groups on the side chains are retained. That is, the total unsaturation of the polymer EBDP is controllable, and the main chain of its vulcanized rubber molecular chain is maximally saturated, which is beneficial to the rubber maintaining durability during aging. The double bonds on the side chains that have not been vulcanized are cross-linked or broken during aging without affecting the breakage of the entire macromolecular network chain of the rubber, thus improving the anti-aging properties of the rubber.

[0041] The EBDP prepared by this invention has a wide molecular weight range, good processing performance, and excellent physical properties of vulcanizates. It was also unexpectedly discovered that the EBDP of this invention is superior to existing EPDM in terms of heat resistance and anti-aging properties.

[0042] The EBDP preparation process of this invention is a homogeneous reaction, simple to prepare, and can be synthesized using existing mature processes, making it easy to control and industrialize. Attached Figure Description

[0043] Figure 1 The GPC spectrum of the hydrogenated polymer EBDP-1# raw gum (BIR) is shown.

[0044] Figure 2 H is the hydrogenated polymer EBDP-1# raw rubber BIR. 1 -NMR.

[0045] Figure 3 H for hydrogenated polymer EBDP-1# 1 -NMR; In the figure, "0.3973" is the hydrogen proton integral value on the carbon atom of the isopropenyl group in the side chain of the hydrogenated gel; "0.1458" is the hydrogen proton integral value on the carbon atom of the remaining double bond in the main chain. Detailed Implementation

[0046] The following examples are intended to further illustrate and describe the content of the present invention, and do not constitute a limitation on the scope of protection of the claims of the present invention.

[0047] In the following examples, the number-average molecular weight and molecular weight distribution index of the polymers were determined using gel permeation chromatography (GPC); H2 was used.1 - The microstructure of the polymer was quantitatively determined by NMR spectroscopy; the mechanical properties of the vulcanized rubber were tested according to GB / T36089-2018.

[0048] Example 1

[0049] Under nitrogen protection, 3000 mL of cyclohexane and 0.6 mL of 12.5% ​​ETE (cyclohexane solution) were added to a 5L polymerization reactor. Stirring was started and the material temperature was raised to 55°C. At this time, 6.0 mL of 0.6 mol / L NBL (cyclohexane solution) and a mixture consisting of 350 mL of butadiene, 48 mL of isoprene and 0.14 mL of divinylbenzene were continuously added to the polymerization reactor. The continuous addition time was 50 min. After the materials were added, polymerization was continued for 30 min. During this period, the polymerization temperature was maintained not higher than 70°C.

[0050] The gel solution was pressurized into a hydrogenation reactor under nitrogen pressure, and 5 mL of 0.6 mol / L NBL was added. The temperature was raised to 75°C, and the mixture was stirred and activated for 10 min under 10 bar hydrogen pressure. Then, 2 mL of a cyclohexane solution of 0.02 mol / L dimethyl phthalate and methyl o-methyl benzoate (co-catalyst, with a molecular ratio of 1:1) was added, and the mixture was activated for another 15 min. At this point, 0.20 g of dicyclopentadiene titanium dichloride was added, and the mixture was stirred for 50 min under 15 bar hydrogen pressure. During this time, the hydrogenation temperature was raised to 110°C. After the reactor temperature dropped to 85°C, another 2 mL of co-catalyst was added, and the mixture was stirred for 50 min under 14 bar hydrogen pressure. Finally, 0.12 g of dicyclopentadiene titanium dichloride and 2 mL of co-catalyst were added to the hydrogenation reactor, and the mixture was stirred for 50 min under 14 bar hydrogen pressure.

[0051] Finally, the hydrogenated adhesive solution was terminated with water, followed by coagulation, dehydration, and drying to obtain 252g of EBDP raw rubber in block form, labeled EBPR-1#. The GPC of the polymer raw rubber BIR is attached. Figure 1 BIR raw rubber and EBDP-1#H 1 -NMR spectra are attached. Figure 2 and attached Figure 3 GPC, microstructure, and Mooney viscosity (ML) of the polymer. 1+4 See Table 1.

[0052] Example 2

[0053] The process conditions of Example 1 were kept unchanged, except that 0.5 mL of 12.5% ​​ETE, 5.5 mL of 0.6 mol / L NBL, and 0.13 mL of divinylbenzene were added. The total amount of the main catalyst, dicyclopentadiene titanium dichloride, used in the hydrogenation unit was 0.30 g (of which 0.20 g was added initially), and the total amount of the co-catalyst was 12 mL (of which 3 mL was added each time initially). The total hydrogenation reaction time was 150 min.

[0054] The results showed that the microstructure and Mooney viscosity of the raw rubber were obtained. 1+4 See Table 1.

[0055] Example 3

[0056] The process conditions of Example 1 were kept unchanged, except that 0.4 mL of 12.5% ​​ETE, 5.0 mL of 0.6 mol / L NBL, 0.18 mL of 1,3,5-hextriene, and 53 mL of isoprene were added.

[0057] The results showed that the microstructure and Mooney viscosity of the raw rubber were obtained. 1+4 See Table 1.

[0058] Example 4

[0059] The process conditions of Example 1 were kept unchanged, except that 0.2 mL of 12.5% ​​ETE, 4.0 mL of 0.6 mol / L NBL, 0.23 mL of 1,3,5-hextriene, and 58 mL of isoprene were added.

[0060] The results showed that the microstructure and Mooney viscosity of the raw rubber were obtained. 1+4 See Table 1.

[0061] Example 5

[0062] The process conditions of Example 1 were kept unchanged, except that 0.8 mL of 12.5% ​​ETE, 8.0 mL of 0.6 mol / L NBL, and 60 mL of isoprene were added.

[0063] The results showed that the microstructure and Mooney viscosity of the raw rubber were obtained. 1+4 See Table 1.

[0064] Example 6

[0065] The process conditions of Example 1 were kept unchanged, except that the amount of isoprene added was 40 mL.

[0066] The results showed that the microstructure and Mooney viscosity of the raw rubber were obtained. 1+4 See Table 1.

[0067] Example 7

[0068] The process conditions of Example 1 were kept unchanged, except that the amount of isoprene added was 70 mL.

[0069] The results showed that the microstructure and Mooney viscosity of the raw rubber were obtained. 1+4 See Table 1.

[0070] Example 8

[0071] The relevant process conditions of Example 2 were kept unchanged, except that the hydrogenation time for each stage was reduced by 10 min, and the total hydrogenation time was 120 min.

[0072] The results showed that the microstructure and Mooney viscosity of the raw rubber were obtained. 1+4 See Table 1.

[0073] Example 9

[0074] Keeping the relevant process conditions of Example 2 unchanged, only the main catalyst for hydrogenation is added at once, and the third-stage co-catalyst addition process is omitted. The amount of hydrogenation co-catalyst used in the first and second stages is 6 mL, and the hydrogenation time is 75 min.

[0075] The results showed that the microstructure and Mooney viscosity of the raw rubber were obtained. 1+4 See Table 1.

[0076] Table 1 Polymer Characterization in the Examples

[0077]

[0078] As shown in Table 1, the unsaturation of the hydride increases with decreasing isoprene dosage, hydrogenation time, and number of times the co-catalyst / main catalyst is added; conversely, the saturation of the hydride increases with decreasing isoprene dosage.

[0079] Example 10

[0080] The trial samples in Table 1, such as EBDP-1#, EBDP-2#, EBDP-3#, EBDP-4#, EBDP-5#, and the control samples EBDP-6#, EBDP-7#, EBDP-8#, EBDP-9#, and commercially available EPDM4045, were mixed, vulcanized, and tested on an open mill according to national standards using the vulcanization formula of EBDP rubber provided in this invention. Their physical properties are shown in Table 2.

[0081] Table 2 Physical properties of vulcanizates

[0082]

[0083] As shown in Table 2, if the unsaturation is too low, the crosslinking density of the vulcanizate is low and the physical properties are poor; if the unsaturation is too high, the anti-aging properties of the vulcanizate are poor.

Claims

1. A hydrogenated random copolymer butadiene-isoprene rubber, characterized in that: It has the structure of Formula 1: ； Formula 1 in, x, y, z, m, n, o, p, and q are the degree of aggregation, and x, y, z, m, n, o, p, and q are all integers greater than or equal to 0; R is a branching unit; (n+o+p+q) / (x+y+z+m)=20~26; (y+z) / (x+m)=17.5~45; (y+m+n+o) / (x+p+z+q)=0.12~0.16; The degree of unsaturation of the hydrogenated random copolymer butadiene-isoprene rubber by iodine value method is 3.0~4.5%.

2. The hydrogenated random copolymer butadiene-isoprene rubber according to claim 1, characterized in that: R is a phenyl or alkylene group.

3. The hydrogenated random copolymer butadiene-isoprene rubber according to claim 1 or 2, characterized in that: The Mooney viscosity ML of the hydrogenated random copolymer butadiene-isoprene rubber 125℃ =65~85, Molecular weight distribution index M w / M n Greater than 1.8, crystallinity <3.

4. A method for preparing a hydrogenated random copolymer butadiene-isoprene rubber according to any one of claims 1 to 3, characterized in that: After heating the polymerization solution system containing the structure regulator to the temperature required for initiating polymerization, a mixture of monomers including butadiene and isoprene, a branching agent, and an initiator are continuously and uniformly added to initiate and carry out the polymerization reaction, thereby obtaining a polymer solution. The polymer solution is then activated and subjected to a catalytic hydrogenation reaction to obtain the final product.

5. The method for preparing a hydrogenated random copolymer butadiene-isoprene rubber according to claim 4, characterized in that: The concentration of the structure modifier in the polymerization solution system is 150~250 mg / kg solvent; the structure modifier includes at least one of tetrahydrofurfuryl ethyl ether, bis(tetrahydrofurfuryl propane), tetrahydrofurfuryl butyl ether, and tetrahydrofurfuryl ethyl ether.

6. The method for preparing a hydrogenated random copolymer butadiene-isoprene rubber according to claim 4, characterized in that: The weight ratio of isoprene to butadiene is 0.15 to 0.

20.

7. The method for preparing hydrogenated random copolymer butadiene-isoprene rubber according to claim 4, characterized in that: The branching agent includes 1,3,5-hextriene and / or divinylbenzene.

8. A method for preparing hydrogenated random copolymer butadiene-isoprene rubber according to claim 4 or 7, characterized in that: The mass of the branching reagent is 0.03 to 0.05% of the mass of the mixed monomers.

9. The method for preparing a hydrogenated random copolymer butadiene-isoprene rubber according to claim 4, characterized in that: The mixed monomers, branching reagents, and initiators are continuously and uniformly added to the polymerization solution system within 40-50 minutes.

10. The method for preparing a hydrogenated random copolymer butadiene-isoprene rubber according to claim 4, characterized in that: The temperature required to initiate the polymerization reaction is 50~55℃, and the maximum temperature during the polymerization reaction shall not exceed 75℃.

11. The method for preparing a hydrogenated random copolymer butadiene-isoprene rubber according to claim 4, characterized in that: The activation and catalytic hydrogenation reaction process includes the following steps: 1) Add alkyl lithium and activate for 10-15 min at a temperature of 65-80℃ and a hydrogen pressure of not less than 10 bar; 2) Add some co-catalyst and activate for 10-15 minutes at a temperature of 65-80℃ and a hydrogen pressure of not less than 10 bar; 3) Add a portion of the main catalyst and add hydrogen for 40-60 minutes at a temperature of 70-120℃ and a hydrogen pressure of 13-16 bar. 4) Add some co-catalyst and add hydrogen for 40-60 minutes at a temperature of 70-120℃ and a hydrogen pressure of 13-16 bar. 5) Simultaneously add the remaining main catalyst and co-catalyst, and add hydrogen for 40-60 minutes at a temperature of 70-120℃ and a hydrogen pressure of 13-16 bar.

12. The method for preparing a hydrogenated random copolymer butadiene-isoprene rubber according to claim 11, characterized in that: The amount of alkyllithium added is 12 to 18 times the total molar amount of the cocatalyst.

13. The method for preparing a hydrogenated random copolymer butadiene-isoprene rubber according to claim 11, characterized in that: The cocatalyst is dimethyl phthalate and / or methyl o-methylbenzoate; The total amount of the co-catalyst added is 1 / 6 to 1 / 8 of the total molar amount of the main catalyst; In steps 2), 4), and 5), the amount of co-catalyst added accounts for 28-38%, 28-38%, and 28-38% of the total molar amount of co-catalyst, respectively.

14. The method for preparing a hydrogenated random copolymer butadiene-isoprene rubber according to claim 11, characterized in that: The main catalyst is dicyclopentadiene titanium dichloride; The total amount of the main catalyst added is 0.12~0.15 g / 100g polymer; In steps 3) and 5), the amount of main catalyst added accounts for 60-80% and 20-40% of the total molar amount of the main catalyst, respectively.

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