Hydrogenated random copolymerized butadiene-isoprene rubber and preparation method thereof

Abstract

The invention discloses hydrogenated random copolymerized butadiene-isoprene rubber and a preparation method thereof. The preparation method comprises the following steps: heating a polymerization solution system containing a structure regulator to a temperature required for initiating polymerization, continuously and uniformly adding a mixed monomer containing butadiene and isoprene, a branching reagent and an initiator, initiating and carrying out a polymerization reaction to obtain a polymer glue solution, and carrying out activation and catalytic hydrogenation reaction on the polymer glue solution to obtain the butadiene-isoprene copolymer. EBPR with wide distribution and good processability is obtained, and vulcanized rubber of the EBPR has high tensile strength, low deformation and excellent anti-aging performance and has wide application.

Description

Technical Field

[0001] The present invention relates to a hydrogenated random copolymer butadiene-isoprene rubber, in particular to a rubber with a wide molecular weight distribution and randomly distributed chain segments including polyethylene, polybutene, polypropylene, polyisoprene and the like in the molecular chain, and also to a preparation method thereof, belonging to the technical field of synthetic rubber. Background Art

[0002] The existing ethylene propylene diene monomer (EPDM) contains 1.4-5.0% (mol) of unsaturation. The vulcanized rubber has excellent ozone resistance, heat resistance, weather resistance and aging resistance, and is widely used in the fields of automobiles and sealing parts, waterproof materials, wires and cables, heat-resistant hoses, tapes, etc. EPDM is synthesized from ethylene, propylene and a small amount of diene hydrocarbons by vanadium-aluminum catalyst. Due to the difference between the monomer concentration and the monomer concentration directly contacting the active center and the difference in the polymerization rate between the monomers, the composition distribution in the synthesized polymer molecules is uneven; usually the content of ethylene in the EPDM molecule is 45-70%, and the application fields and directions of EPDM with different amounts of ethylene chain segments are also different. For example, the copolymer containing 70% or more ethylene chain segments obtained by synthesis has a higher elongation of the vulcanized rubber, a longer sequence of ethylene chain segments, and a deterioration of the relaxation performance of the copolymer. The longer block ethylene chain segments are easy to crystallize, and their role is like the node of the transverse physical bond. The presence of microcrystalline phase in the polymer can increase its tensile strength, but the tensile deformation also increases at the same time. The existing EPDM synthesis technology is difficult to form a uniform alternating copolymer of ethylene, propylene and a small amount of diene monomers to reduce the crystallization tendency of the polymer. In addition, the Mooney viscosity of the existing commercially available EPDM is 18 to 90; the main chain is a saturated straight chain, and the iodine value of the side chain is 6 to 30g / 100g.

[0003] It is not difficult to obtain a polymer containing polyethylene and polybutene segments by partially hydrogenating a certain amount of 1.2-addition polybutadiene rubber. At present, this type of hydride has not been reported. Such derivative polymers are common lithium-based polymerization and hydrogenation polystyrene-B-conjugated diene hydrides such as SEBS or SEPS, etc. The iodine value of the polymer is 1 to 10 g / 100 g. Due to its narrow molecular weight distribution, it cannot be vulcanized with sulfur and behaves like a thermoplastic elastomer.

[0004] Existing nickel-based and rare earth-catalyzed conjugated dienes are all high-cis rubbers, with a 1,4-addition unit content of >95%. The polymerized rubber contains catalyst residues, which can easily poison the active lithium-titanocenes. On the other hand, after hydrogenation, the molecular chain of high-cis conjugated diene rubbers presents long polyethylene chain segments, and the hydride crystallizes to show high modulus plastic behavior.

[0005] Chinese patent (CN1884328A) relates to a method for preparing branched high-vinyl polybutadiene rubber by molybdenum catalysis, and Chinese patent (CN105199028A) discloses a high-vinyl polybutadiene rubber with adjustable microstructure and its preparation method, but the polymer prepared by the above technology is not easy to hydrogenate. At the same time, ("High-vinyl polybutadiene oil-extended rubber and its preparation method", Rubber Science and Technology, Issue 04, 2013) discloses a high-vinyl polybutadiene oil-extended rubber and its preparation method, and ("Molecular design of star-shaped medium-vinyl polybutadiene rubber", 2004 International Rubber Conference Proceedings (A)) discloses a molecular design of star-shaped medium-vinyl polybutadiene rubber. The above technologies all belong to Ziegler-Natta improved coordination polymerization, and there is no report on hydrogenation of the polymer. Chinese patent (CN102863576A) discloses a composite structure regulator suitable for preparing 3,4-isoprene rubber and a method for preparing 3,4-isoprene rubber, specifically, a composite structure regulator suitable for preparing 3,4-isoprene rubber and a method for preparing 3,4-isoprene rubber. At a relatively high polymerization temperature, the 3,4 structure content of the polymer can be efficiently adjusted, and the 3,4 structure content of the obtained product is above 70%. When these polymers are used in automobile tire tread rubber, the tread has good anti-skid properties and low rolling resistance. The above patent also does not describe the hydrogenation of its polymer. In addition, the hydrogenated products of lithium-based polymerized polystyrene-isoprene copolymers, such as SEP produced by KRATON, have fully hydrogenated double bonds in the molecules. This type of SEP can only be used as an oil thickener because it does not contain double bonds in its molecules, so it cannot be vulcanized and does not reflect the behavior of rubber.

[0006] In summary, currently EPDM and existing anionic polystyrene-conjugated diene hydrogenates such as SEBS, SEPS, and SEP are thermoplastic elastomers, not vulcanized rubbers. However, there is no relevant technology report on the preparation of hydrogenates of anionic diene copolymers. Summary of the invention

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

[0008] The first object of the present invention is to provide a hydrogenated random copolymer butadiene-isoprene rubber (EBDP) with wide molecular weight distribution, easy processing and aging resistance, and its vulcanized rubber has high tensile strength, low deformation and excellent aging resistance.

[0009] The second object of the present invention is to provide a method for preparing the EBDP with simple operation and low cost. The method first synthesizes a polybutadiene-isoprene rubber (BIR) with a pendant olefin content of 30 to 55% by an anionic polymerization method, and then selectively hydrogenates to obtain a hydrogenated random copolymer butadiene-isoprene rubber EBDP having a polyethylene-butylene-propylene-isopropylene structure. In the method, butadiene and isoprene monomers can be completely converted, the polymerization reaction time is short, and various technical deficiencies and drawbacks existing in the existing EPDM preparation process are avoided.

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

[0011]

[0012] Wherein, x, y, z, m, n, o, p and q are the polymerization degrees; R is 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 0 at the same time, and x, p, z and q are not 0 at the same time. R can be a unit introduced by the branching agent divinylbenzene or 1,3,5-hexatriene.

[0013] The EBDP of the present invention contains only a trace amount of double bonds on the main chain, and the majority of polyethylene and saturated alkyl groups have a structure similar to saturated hydrocarbons in the polyolefin chain, so EBDP and polyolefins have good compatibility and do not produce phase separation. At the same time, the trace amount of double bonds on the main chain of EBDP and the relatively large amount of double bonds on the side chain can form a network-like macromolecule through vulcanization. Even if there are a small amount of double bonds that have not been cross-linked in the rubber after vulcanization, they are not completely on the main chain during the later cross-linking aging, which ensures that the polymer or composite material has excellent anti-aging behavior.

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

[0015] The polymer units in the EBDP of the present invention are randomly distributed, which can effectively reduce the crystallinity of the polymer, so that the polymer also has the characteristics of low crystallinity and low deformation.

[0016] As a preferred solution, the hydrogenated random copolymer butadiene-isoprene rubber has an iodine value method unsaturation of 3.0-4.5% (moL). The unsaturation ratio of 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 solution, in the hydrogenated random copolymer butadiene-isoprene rubber before hydrogenation, the total mass proportion of 1,2 structural units of butadiene and 3,4 structural units of isoprene in the raw rubber is 25-60%, more preferably 30-55%.

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

[0019] As a preferred embodiment, the Mooney viscosity ML of the hydrogenated random copolymer butadiene-isoprene rubber is 125 ℃=65~85, molecular weight distribution index M w / M n Greater than 1.8, crystallinity <3.

[0020] The present invention also provides a method for preparing hydrogenated random copolymer butadiene-isoprene rubber, which comprises heating a polymerization solution system containing a structure regulator to a temperature required for initiating polymerization, continuously and evenly adding a mixed monomer including butadiene and isoprene, a branching agent and an initiator, initiating and carrying out a polymerization reaction to obtain a polymer glue solution, and the polymer glue solution is subjected to activation and catalytic hydrogenation reaction to obtain the obtained product.

[0021] As a preferred solution, the concentration of the structure regulator in the polymerization solution system is 150-250 mg / kg solvent. As a more preferred solution, the structure regulator includes at least one of tetrahydrofurfuryl alcohol ethyl ether, ditetrahydrofurfuryl propane, tetrahydrofurfuryl alcohol butyl ether, and tetrahydrofurfuryl alcohol hexyl ether. The solvent is a conventional hydrocarbon solvent, such as cyclohexane. Selecting a suitable structure regulator and dosage can effectively adjust the 1,2 polymerization ratio of butadiene and the 3,4 polymerization ratio of isoprene, thereby effectively adjusting the content of the side alkyl and side olefin groups in the hydrogenated random copolymer butadiene-isoprene rubber.

[0022] As a preferred solution, the weight ratio of the isoprene to the butadiene is 0.15 to 0.20. The mass ratio of isoprene should not be too high or too low. If the amount of isoprene is too high, the unsaturation of the polyisoprene unit in the subsequent polymer hydrogenation will be too high, and the physical properties of the polymer will decrease, mainly reflected in the anti-aging and filling capacity of oil products and inorganic fillers. If the amount of isoprene is too low, the content of the introduced side olefin group is too low, which reduces the degree of vulcanization crosslinking and reduces the performance of the vulcanized rubber.

[0023] As a preferred solution, the branching agent includes 1,3,5-hexatriene and / or divinylbenzene. When 1,3,5-hexatriene is selected as the branching agent, it has a branching effect only when 1,2-addition occurs, and in the polymerization reaction system of the present invention, the probability of 1,2-addition is 30-55%; 1,3,5-hexatriene cannot produce branched chains in the 1,4-addition, and only produces short side olefin chains. In anionic polymerization, while the molecular chain grows, branching also occurs simultaneously, thereby increasing the weight average molecular weight of the polymer and widening the molecular weight distribution index of the polymer.

[0024] As a more preferred solution, the mass of the branching agent is 0.03-0.05% of the mass of the mixed monomer. Too much branching agent is not suitable, because it is easy to produce macromolecular gel, which is disadvantageous. If the branching agent is not suitable too little, it is difficult to achieve the purpose of widening the molecular weight distribution.

[0025] As a preferred solution, the mixed monomer may also include piperylene.

[0026] As a preferred solution, the mixed monomer, the branching agent and the initiator are respectively added to the polymerization solution system continuously and uniformly within 40 to 50 minutes. By controlling the uniform and continuous addition of the mixed monomer, the branching agent and the initiator, etc., the highly random copolymerization of the polymer can be effectively regulated, thereby adjusting the uniform distribution of the side vinyl group and the side isopropylene group in the EBDP, and improving the vulcanization effect of the EBDP.

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

[0028] As a preferred solution, the activation and catalytic hydrogenation reaction process comprises the following steps: 1) adding alkyl lithium, activating for 10 to 15 minutes at a temperature of 65 to 80° C. and a hydrogen pressure of not less than 10 bar; 2) adding part of the promoter, activating for 10 to 15 minutes at a temperature of 65 to 80° C. and a hydrogen pressure of not less than 10 bar; 3) adding part of the main catalyst, hydrogenating for 40 to 60 minutes at a temperature of 70 to 120° C. and a hydrogen pressure of 13 to 16 bar; 4) adding part of the promoter, hydrogenating for 40 to 60 minutes at a temperature of 70 to 120° C. and a hydrogen pressure of 13 to 16 bar; 5) adding the remaining main catalyst and promoter at the same time, hydrogenating for 40 to 60 minutes at a temperature of 70 to 120° C. and a hydrogen pressure of 13 to 16 bar.

[0029] As a more preferred solution, the amount of alkyl lithium added is 12 to 18 times the total molar amount of the co-catalyst.

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

[0031] As a more preferred solution, 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 more preferred solution, the amount of the co-catalyst added in step 2), step 4) and step 5) accounts for 28-38%, 28-38% and 28-38% of the total molar amount of the co-catalyst, respectively.

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

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

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

[0036] The present invention selects a dicyclopentadiene titanium dichloride catalyst system, which has a hydrogenation rate of more than 99% for double bonds in butadiene polymerization units, while for isoprene polymerization units, due to the steric hindrance effect of the side methyl groups and the methyl groups on the isopropylene double bonds in the molecules, the double bonds are not easy to be hydrogenated, and the double bonds on the main chain are easy to be hydrogenated with the double bonds on the isopropylene on the side chain. The goal of the present invention is to hydrogenate the double bonds on the main chain as much as possible, while retaining the double bonds on the side chains, which provide crosslinking points for subsequent application vulcanization, and the fewer the number of double bonds on the main chain, the more the number of double bonds on the side chains is relatively, which is beneficial to the anti-aging property of the vulcanized rubber, and the use of the dicyclopentadiene titanium dichloride catalyst system can achieve the expected selective hydrogenation effect. In addition, the main catalyst and the auxiliary catalyst are added to the hydrogenation system for catalytic hydrogenation in multiple times because the catalytic hydrogenation of the present invention belongs to active complex catalysis, the activity of the catalyst is relatively high at the initial stage, and it can complete 85% hydrogenation of the polybutadiene unit, but the activity decreases rapidly in the later stage. Therefore, the purpose of adding the catalyst in the later stage is to re-manufacture or establish a new catalytic active center, and hydrogenate the polybutadiene unit and the 1,4-addition polymerization unit of isoprene as much as possible, so as to retain the side isopropenyl functional group generated by the 3,4-addition of isoprene as much as possible.

[0037] The EBDP rubber of the present invention can be vulcanized by a conventional vulcanizing rubber formula. The specific vulcanizing rubber formula is, for example, (mass parts of components): 100 parts of EBDP, 25 parts of softening filler oil, 60 parts of carbon black, 1.5 parts of accelerator T, and 1.5 parts of sulfur. The vulcanized rubber is mixed and vulcanized according to national standards, and the vulcanization conditions are: 160°C / 20min.

[0038] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0039] In the preparation process of EBDP of the present invention, the polymerization time of the progel BIR is short, the molecular weight distribution is controllable, and the EBDP can be prepared by the existing anionic polymerization process, which is conducive to industrial production.

[0040] In the preparation process of the EBDP of the present invention, the amount of isoprene monomer is easily adjusted and hydrogenated by using a special titanocene catalyst system, so that the content of the side vinyl groups in the EBDP can be regulated. The titanocene catalyst system can selectively hydrogenate the double bonds on the main chain to the maximum extent, while the isopropenyl groups on the side chains, in particular, are retained, that is, the total unsaturation degree of the polymer EBDP is controllable, and the main chain in the vulcanized rubber molecular chain is saturated to the maximum extent, which is beneficial to maintaining the durability of the rubber during the aging process. The residual double bonds on the side chains that are not vulcanized are cross-linked or broken during the aging process without affecting the breaking of the entire macromolecular network chain of the rubber, that is, the anti-aging performance of the rubber is improved.

[0041] The EBDP prepared by the present invention has a wide molecular weight, good processing performance, and excellent physical properties of the vulcanized rubber. It is unexpectedly found that the EBDP of the present invention is better than the existing EPDM in terms of heat resistance and anti-aging performance.

[0042] The EBDP preparation process of the present invention belongs to a homogeneous reaction, has simple preparation, can be synthesized by using existing mature processes, and is easy to control and industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is the GPC spectrum of hydrogenated polymer EBDP-1# raw rubber BIR.

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

[0045] Figure 3 H is the hydrogenation polymer EBDP-1# 1 -NMR; in the figure, "0.3973" is the integral value of hydrogen protons on the carbon atoms of the isopropenyl group on the side branch of the hydrogenated rubber; "0.1458" is the integral value of hydrogen protons on the residual double bond carbon atoms in the main chain. DETAILED DESCRIPTION

[0046] The following examples are intended to further illustrate the present invention in detail and are not intended to limit 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 by gel permeation chromatography (GPC);1 -NMR spectroscopy is used to quantitatively determine the microstructure of the polymer; the mechanical properties of the vulcanized rubber are tested according to the GB / T36089-2018 method.

[0048] Example 1

[0049] Under nitrogen protection, 3000 mL of cyclohexane and 0.6 mL of ETE (cyclohexane solution) with a mass fraction of 12.5% ​​were added to a 5L polymerization kettle, 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 of 350 mL of butadiene, 48 mL of isoprene and 0.14 mL of divinylbenzene were continuously added to the polymerization kettle. The continuous addition time was 50 min. After the materials were added, the polymerization was continued for another 30 min, during which the polymerization temperature was maintained at no more than 70°C.

[0050] The glue liquid was pressed into the hydrogenation kettle with nitrogen, 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 0.02 mol / L cyclohexane solution of dimethyl phthalate and methyl o-toluate (cocatalyst, the molecular ratio of the two cocatalysts was 1:1) was added and activated for another 15 min, then 0.20 g of dicyclopentadiene titanium dichloride was added, and the mixture was stirred for 50 min under 15 bar hydrogen pressure, during which the hydrogenation temperature rose to 110°C, and after the kettle temperature dropped to 85°C, 2 mL of cocatalyst was added and the mixture was stirred for 50 min under 14 bar hydrogen pressure; then 0.12 g of dicyclopentadiene titanium dichloride and 2 mL of cocatalyst were added to the hydrogenation kettle and the mixture was stirred for 50 min under 14 bar hydrogen pressure.

[0051] Finally, the hydrogenated rubber solution was terminated with water, condensed, dehydrated and dried to obtain 252g of block EBDP raw rubber, which was labeled as EBPR-1#. The GPC of polymer raw rubber BIR is shown in the attached Figure 1 , BIR original 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 relevant process conditions of Example 1 remain 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 are added. The total amount of dicyclopentadiene titanium dichloride used as the main catalyst for the hydrogenation unit is 0.30 g (of which the first addition amount is 0.20 g), the total amount of the co-catalyst is 12 mL (of which each first addition amount is 3 mL), and the total hydrogenation reaction time is 150 min.

[0054] Results The microstructure and Mooney viscosity ML of the raw rubber were obtained. 1+4 )See Table 1.

[0055] Example 3

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

[0057] Results The microstructure and Mooney viscosity ML of the raw rubber were obtained. 1+4 )See Table 1.

[0058] Example 4

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

[0060] Results The microstructure and Mooney viscosity ML of the raw rubber were obtained. 1+4 )See Table 1.

[0061] Example 5

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

[0063] Results The microstructure and Mooney viscosity ML of the raw rubber were obtained. 1+4 )See Table 1.

[0064] Example 6

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

[0066] Results The microstructure and Mooney viscosity ML of the raw rubber were obtained. 1+4 )See Table 1.

[0067] Example 7

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

[0069] Results The microstructure and Mooney viscosity ML of the raw rubber were obtained. 1+4 )See Table 1.

[0070] Example 8

[0071] The relevant process conditions of Example 2 remain unchanged, except that each hydrogenation time is reduced by 10 minutes, and the total hydrogenation time is 120 minutes.

[0072] Results The microstructure and Mooney viscosity ML of the raw rubber were obtained. 1+4 )See Table 1.

[0073] Example 9

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

[0075] Results The microstructure and Mooney viscosity ML of the raw rubber were obtained. 1+4 )See Table 1.

[0076] Table 1 Analysis of polymer characteristics in the examples

[0077]

[0078] As can be seen from Table 1, as the amount of isoprene used, the hydrogenation time and the number of times the co-catalyst / main catalyst is added decreases, the unsaturation of the hydride increases; and as the amount of isoprene used decreases, the saturation of the hydride increases.

[0079] Example 10

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

[0081] Table 2 Physical properties of vulcanized rubber

[0082]

[0083] As can be seen from Table 2, if the unsaturation degree is too low, the cross-linking density of the vulcanized rubber is low and the physical properties are poor; if the unsaturation degree is too high, the anti-aging performance of the vulcanized rubber is poor.

Claims

1. A hydrogenated random copolymer butadiene-isoprene rubber, characterized in that: It has the structure of formula 1: in, x, y, z, m, n, o, p and q are the degrees of polymerization, 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.

2. The hydrogenated random copolymer butadiene-isoprene rubber according to claim 1, characterized in that: The unsaturation degree of the hydrogenated random copolymer butadiene-isoprene rubber according to the iodine value method is 3.0-4.5%.

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

4. A hydrogenated random copolymer butadiene-isoprene rubber according to claim 1, 2 or 3, 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.

5. The method for preparing a hydrogenated random copolymer butadiene-isoprene rubber according to any one of claims 1 to 4, characterized in that: After the polymerization solution system containing the structure regulator is heated to the temperature required for initiating polymerization, a mixed monomer including butadiene and isoprene, a branching agent and an initiator are continuously and evenly added to initiate and carry out a polymerization reaction to obtain a polymer glue solution, and the polymer glue solution is subjected to activation and catalytic hydrogenation reaction to obtain the polymer glue solution.

6. The method for preparing hydrogenated random copolymer butadiene-isoprene rubber according to claim 5, characterized in that: The concentration of the structure regulator in the polymerization solution system is 150-250 mg / kg solvent; the structure regulator includes at least one of tetrahydrofurfuryl alcohol ethyl ether, ditetrahydrofurfuryl propane, tetrahydrofurfuryl alcohol butyl ether and tetrahydrofurfuryl alcohol hexyl ether.

7. The method for preparing hydrogenated random copolymer butadiene-isoprene rubber according to claim 5, characterized in that: The weight ratio of the isoprene to the butadiene is 0.15 to 0.

20.

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

9. The method for preparing hydrogenated random copolymer butadiene-isoprene rubber according to claim 5 or 8, characterized in that: The mass of the branching agent is 0.03-0.05% of the mass of the mixed monomer.

10. The method for preparing hydrogenated random copolymer butadiene-isoprene rubber according to claim 5, characterized in that: The mixed monomer, branching agent and initiator are respectively and continuously added into the polymerization solution system uniformly within 40 to 50 minutes.

11. The method for preparing hydrogenated random copolymer butadiene-isoprene rubber according to claim 5, characterized in that: The temperature required to initiate the polymerization reaction is 50-55°C, and the maximum temperature during the polymerization reaction does not exceed 75°C.

12. The method for preparing hydrogenated random copolymer butadiene-isoprene rubber according to claim 5, characterized in that: The process of activation and catalytic hydrogenation reaction comprises the following steps: 1) Add alkyl lithium and activate for 10 to 15 minutes at a temperature of 65 to 80° C. and a hydrogen pressure of not less than 10 bar; 2) adding part of the promoter and activating for 10 to 15 minutes at a temperature of 65 to 80°C and a hydrogen pressure of not less than 10 bar; 3) adding part of the main catalyst, and hydrogenating for 40 to 60 minutes at a temperature of 70 to 120° C. and a hydrogen pressure of 13 to 16 bar; 4) adding part of the promoter, and hydrogenating for 40 to 60 minutes at a temperature of 70 to 120° C. and a hydrogen pressure of 13 to 16 bar; 5) Add the remaining main catalyst and co-catalyst at the same time, and hydrogenate for 40 to 60 minutes at a temperature of 70 to 120° C. and a hydrogen pressure of 13 to 16 bar.

13. The method for preparing hydrogenated random copolymer butadiene-isoprene rubber according to claim 12, characterized in that: The amount of alkyl lithium added is 12 to 18 times the total molar amount of the co-catalyst.

14. The method for preparing hydrogenated random copolymer butadiene-isoprene rubber according to claim 12, characterized in that: The co-catalyst is dimethyl phthalate and / or methyl o-toluate; The total amount of the co-catalyst added is 1 / 6 to 1 / 8 of the total molar amount of the main catalyst; The amount of the co-catalyst added in step 2), step 4) and step 5) accounts for 28-38%, 28-38% and 28-38% of the total molar amount of the co-catalyst respectively.

15. The method for preparing hydrogenated random copolymer butadiene-isoprene rubber according to claim 12, characterized in that: The main catalyst is dicyclopentadiene titanium dichloride; The total amount of the main catalyst added is 0.12-0.15 g / 100 g polymer; The amount of the main catalyst added in step 3) and step 5) accounts for 60-80% and 20-40% of the total molar amount of the main catalyst respectively.

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