Polyethylene-butylene rubber and preparation method thereof

Abstract

The invention discloses polyethylene-butylene rubber and a preparation method thereof, and belongs to the field of rubber. The polyethylene-butylene rubber has a triblock structure, polyethylene chain links are mainly arranged at two ends, a polyethylene / poly (1-butylene) random chain link with higher side group content is arranged in the middle, the special structure of the polyethylene-butylene rubber gives good elasticity and tensile strength to the rubber, and the polyethylene-butylene rubber can be used as a polyolefin thermoplastic elastomer and has the characteristics of good physical and mechanical properties and easiness in processing; more importantly, the E-BEB-E has excellent thermal aging resistance, and the E-BEB-E can be used for modifying polyolefin resin to prepare a thermoplastic E-BEB-E / polyolefin elastic material (TPV) and a PP / E-BEB-E thermoplastic hard alloy.

Description

Technical Field

[0001] The invention relates to polyethylene-butene rubber and a preparation method thereof, belonging to the technical field of new rubber materials. Background Art

[0002] Traditional commercially available ethylene-propylene rubber (EPDM) is copolymerized by ethylene, propylene and dienes. According to its different molecular structure characteristics, its application types and product models reach more than 20 kinds.

[0003] The ethylene-propylene ratio of EPDM can be changed during the polymerization stage. When the ethylene-propylene ratio changes from 50 / 50 to 80 / 20, the positive effects are: higher green strength, higher tensile strength, higher crystallization, higher glass transition temperature, the ability to convert the raw polymer into pellets, and better extrusion characteristics. The negative effects are poor calendering mixing, poor low temperature characteristics and lower compression set. When the propylene ratio is higher, the benefits are better processing performance, improved low temperature characteristics and higher compression set. The molecular weight of EPDM is usually expressed as Mooney viscosity. The Mooney viscosity value of EPDM is obtained at a high temperature of 125°C. The main reason is to eliminate the crystallization caused by the high ethylene content, which will mask the true molecular weight of the polymer. The Mooney viscosity of EPDM ranges from 20 to 100. Its molecular weight distribution index varies from 2 to 5. As the molecular weight distribution increases, the mixing and milling processability increases. However, a narrower molecular weight distribution can improve the vulcanization rate, the cure state and the injection molding behavior. EPDM can be vulcanized with peroxide or sulfur. However, compared to sulfur vulcanization, peroxide cross-linked EPDM has higher temperature resistance, lower compression set and improved vulcanization characteristics when used in the wire and cable industry.

[0004] In "Thermoplastic Elastomers", 99 rubber / plastic blends prepared from 11 rubbers and 9 plastics were reviewed. The study found that to obtain the best performance of the rubber / thermoplastic dynamic vulcanization blend, the surface energy of the two polymers of plastic and rubber must match, the length of the rubber entanglement molecular chain is low, and the crystallinity of the plastic is greater than 15%. When the polarity or surface energy difference between the plastic and the rubber is relatively large, adding a suitable compatibilizer and then dynamically vulcanizing can also obtain a blend with excellent performance. Commercially available PP / PE / EPDM and PP / EPDM can form dynamically vulcanized thermoplastic elastomers (TPV), accounting for 90% of the total TPV, mainly because PP and EPDM materials have better compatibility, the vulcanization system that EPDM can use is relatively mature, and EPDM has very good weather resistance, and ultimately has a medium raw material cost. Thermoplastic ethylene propylene rubber (EPDM / PP) is a product in which EPDM is mixed with PP based on EPDM as the main body. At the same time, the EPDM reaches the expected degree of crosslinking. It not only retains the inherent properties of EPDM, but also has significant thermoplastic injection, extrusion, blow molding and calendering processing properties.

[0005] However, the existing EPDM and PP / EPDM dynamically vulcanized thermoplastic elastic materials have the characteristics of large compression deformation, poor calendering miscibility and low temperature resistance. How to improve and overcome these defects, that is, to produce vulcanized rubber and plastic materials with high strength, moderate crystallization, good compatibility with PP, good aging resistance, low deformation, high modulus and resilience is the current human yearning for a better life. Summary of the invention

[0006] The existing EPDM and PP / EPDM dynamically vulcanized thermoplastic elastic materials have the defects of large compression deformation, poor calendering miscibility and low-temperature resistance, and the current situation that polyethylene-butylene rubber has not yet been industrialized.

[0007] The first object of the present invention is to provide a polyethylene-butene rubber (abbreviated as E-BEB-E), the two ends of the rubber are mainly polyethylene links, and the middle is a polyethylene / poly 1-butene random link with a high side group content. Its special structure gives the rubber good elasticity and tensile strength (like the well-known block polymers such as SBS and SEBS), and can be used as a polyolefin thermoplastic elastomer, with good physical and mechanical properties and easy processing. More importantly, it also embodies excellent heat aging resistance. The E-BEB-E can be used for the modification of polyolefin resins to prepare thermoplastic E-BEB-E / polyolefin dynamically vulcanized elastic materials (TPV) and PP / E-BEB-E thermoplastic hard alloys.

[0008] The second object of the present invention is to provide a method for preparing polyethylene-butene rubber, which adopts solution polymerization method for synthesis, has simple method, low cost, can be produced by using existing mature equipment and process, and is easy to industrialize.

[0009] In order to achieve the above technical objectives, the present invention provides a polyethylene-butene rubber having a structure of Formula 1:

[0010]

[0011] in,

[0012] n, m, x, y, n1, m1, x1, y1, n2, m2, x2 and y2 are degrees of polymerization;

[0013] (x+y) / (x+y+n+m)﹤0.14;

[0014] (x1+y1) / (x1+y1+n1+m1)=0.35~0.60;

[0015] (x2+y2) / (x2+y2+n2+m2)﹤0.14;

[0016] (x+y+x1+y1+x2+y2) / (n+m+n1+m1+n2+m2+x+y+x1+y1+x2+y2)=0.20~0.40;

[0017] The double bond hydrogenation rate is 99.50-99.75%.

[0018] The double bond hydrogenation rate of the present invention refers to the molar percentage of hydrogenated butadiene units in the total butadiene units.

[0019] The E-BEB-E rubber of the present invention is obtained by hydrogenating polybutadiene obtained by anionic polymerization, and the hydrogenation rate reaches 99.5% to 99.75%. The small amount of double bonds remaining can be used for crosslinking and vulcanization. E-BEB-E has a triblock structure, and its two ends are polybutadiene with a high 1,4-polymerization ratio. After hydrogenation, it mainly forms a polyethylene block, i.e., an E block, which has a relatively high crystallinity, while the middle segment is a polybutadiene with a high 1,2-polymerization ratio. After hydrogenation, it mainly forms a polyethylene / poly-1-butene random block, i.e., a BEB block, which has a very low crystallinity and has soft segment properties. The E block in the molecule of E-BEB-E rubber can provide a physical crosslinking point for the polymer, giving the polymer a high tensile strength, while the BEB block gives the polymer good flexibility, high resilience and other properties, and the trace double bonds provide a chemical vulcanization crosslinking point for the polymer. The polymer after vulcanization forms a network macromolecule with a certain elastic modulus, which improves the comprehensive physical properties of the macromolecule. Especially after compounding it with polyolefin resin, it produces better flexibility, high resilience, high elastic modulus, low compression deformation and aging resistance.

[0020] As a preferred scheme, (x+y+x1+y1+x2+y2) / (n+m+n1+m1+n2+m2+x+y+x1+y1+x2+y2)=0.25~0.30.

[0021] As a preferred solution, (x+y+n+m):(x1+y1+n1+m1):(x2+y2+n2+m2)=(0.50-2.5):(3.5-5.0):(0.50-2.5). The number average molecular weight M of the E blocks at both ends of the E-BEB-E rubber of the present invention is n (0.50~2.5)×10 4 If the molecular weight is too low, the crystallinity is too low and the tensile strength of the polymer is too low. If the molecular weight is too high, the BEB molecular chain presents a disordered distribution of random segments. If the molecular weight is too low, the modulus of the polymer increases and the elasticity decreases. The molecular weight M of the middle BEB block n (3.5~5.0)×10 4 .

[0022] As a preferred solution, the Mooney viscosity ML 125℃The Mooney viscosity of the rubber is usually measured at 100°C / (1+4min). The E-BEB-E molecule of the present invention contains a highly isotactic E block and has a relatively high crystallization performance. The polymer molecules are not completely randomly distributed and cannot accurately reflect the molecular weight of the polymer (the Mooney viscosity and the molecular weight present a corresponding relationship). Therefore, the Mooney viscosity of the polymer of the present invention is measured at 125°C / (1+4min), which can eliminate the crystallization and cohesive energy of the polymer. If the Mooney viscosity is too large, melt fracture will occur when it is blended and extruded with a polyolefin resin, and defects will occur in the product. That is, it is more suitable that the melting temperatures of the polyolefin polymer and the polyolefin are not much different.

[0023] As a preferred solution, the molecular weight distribution M w / M n =1.3 to 1.5. The molecular weight distribution of the E-BEB-E rubber of the present invention is a medium narrow distribution.

[0024] As a preferred solution, the E-BEB-E number average molecular weight M n 6.0~8.0×10 4 .

[0025] The present invention also provides a method for preparing polyethylene-butene rubber. The method comprises the following steps: firstly heating the system of anionic polymerization solution containing an activator and hindered amine molecules to 80-90°C, adding alkyl lithium and butadiene to carry out a first-stage polymerization, then cooling the system to 50-60°C, adding butadiene to carry out a second-stage polymerization, then heating the system to 75-85°C, adding butadiene to carry out a third-stage polymerization, and after the polymerization is completed, carrying out a catalytic hydrogenation reaction, and the hydrogenated rubber solution is subjected to termination, devolatilization and pelletizing to obtain the product.

[0026] In the preparation process of the polyethylene-butene rubber of the present invention, high-temperature polymerization is adopted in the first stage polymerization and the third stage polymerization to produce more 1,4-polymer structures, which is convenient for producing longer polyethylene blocks after hydrogenation. Low-temperature polymerization is adopted in the second stage polymerization to produce more 1,2-polymer structures, which is convenient for producing more ethyl side chains after hydrogenation, thereby increasing the disordered distribution of the hydrogenated polyethylene and poly-1-butene and the elasticity of the entire polymer.

[0027] As a preferred solution, the activator is tetrahydrofuran. Further preferably, the concentration of the activator in the anionic polymerization solution system is 50-100 mg / kg. Tetrahydrofuran (THF) is a commonly used activator in the anionic polymerization process of styrene-butadiene polymers (SBS). For example, the 1,2-polymerization structure in the butadiene chain segment of the commercially available SBS molecule is not higher than 14%. The higher the amount of THF used, the higher the content of 1,2-polymerization structure; the lower the amount of THF used, the lower the content of 1,2-polymerization structure. In addition, the higher the polymerization temperature, the lower the content of 1,2-polymerization structure, and the lower the polymerization temperature content, the higher the content of 1,2-polymerization structure. The polymerization mechanism of the Lewis bases used in the anionic polymerization process, such as regulators or activators, is the same, except that the regulating ability of different Lewis bases is different. Among the Lewis bases, THF has the worst regulating ability, but it is beneficial for preparing higher content 1,4-adducts such as SBS. This is why the present invention uses high-temperature polymerization in the first and third stage polymerizations to produce more 1,4-polymer structures, which is convenient for producing longer polyethylene blocks after hydrogenation, and uses low-temperature polymerization in the second stage polymerization to produce more 1,2-polymer structures, which is convenient for producing more ethyl side chains after hydrogenation, and increase the disordered distribution of hydride polyethylene and poly-1-butene and the elasticity of the entire polymer. In addition, hindered amine molecules are also a kind of Lewis base and have a regulating function. They can slow down the polymerization rate and widen the molecular weight distribution of the polymer, which is described in (US4451576A). The present invention uses THF as an activating agent for initiation, so that the probability of 1,2-polymerization of butadiene is less than 14%, so that butadiene can be 1,4-polymerized to the maximum extent, and an E block containing more than 86% polyethylene can be formed after hydrogenation.

[0028] As a preferred solution, the hindered amine molecules include at least one of 1,5-diazabicyclo[5.4.0]-undec-5-ene and 1,5-diazabicyclo[4.3.0]-5-nonene; the concentration of the hindered amine molecules in the anionic polymerization solution system is 100-150 mg / kg.

[0029] As a preferred solution, the total molar ratio of the alkyl lithium to butadiene is 1:(6.0-8.0)×10 4 .

[0030] As a preferred solution, the time of the first stage polymerization is 20 to 25 minutes, the time of the second stage polymerization is not less than 30 minutes, and the time of the third stage polymerization is 25 to 35 minutes. The higher the temperature of the first stage polymerization and the third stage polymerization, the higher the 1,4-addition ratio of butadiene, and the isotactic polyethylene block E can be formed after hydrogenation. The temperature of the second stage polymerization should be slightly lower, which is more conducive to the 1,2-polymerization of butadiene, so as to avoid the loss of elasticity of the polymer due to excessive butadiene 1,4-polymer units in the polymer molecule after hydrogenation to produce polyethylene chain segments, that is, in the original rubber synthesis, this polymer block should have a quantitative 1,2-polymer units and 1,4-polymer units to form a random arrangement, and the hydrogenated polymer has the behavior of rubber, so the second stage polymerization is carried out at a low temperature for a period of time to produce a quantitative 1,2-polymer units and 1,4-polymer units random copolymerization soft segment, and the polymerization time is not less than 30 minutes.

[0031] As a preferred solution, the conditions for the catalytic hydrogenation reaction are: using active lithium as an activator, a titanium-based catalyst system, a hydrogen pressure of 13 to 16 bar, a temperature of 75 to 110° C., and a time of not less than 90 minutes.

[0032] As a preferred solution, the titanium-based catalyst system includes dicyclopentadiene titanium dichloride as a main catalyst and dimethyl phthalate and / or methyl o-toluate as a co-catalyst; the molar ratio of the main catalyst to the co-catalyst is (3-8):1.

[0033] As a preferred solution, the molar ratio of the active lithium to the main catalyst is (6-12): 1. The preferred active lithium is alkyl lithium, for example, n-butyl lithium.

[0034] As a preferred solution, the amount of the titanium-based catalyst system added is measured as 0.01 to 0.05 g / 100 g of polymer based on the amount of the main catalyst.

[0035] As a preferred solution, the solvent in the anionic polymerization solution system is a hydrocarbon solvent, preferably cyclohexane. The mass fraction of the butadiene monomer in the solvent is 12-14%.

[0036] As a preferred solution, the termination is carried out by water.

[0037] As a preferred solution, the devolatilization is carried out by using a twin-screw extruder to remove volatile components.

[0038] The E-BEB-E of the present invention is a transparent granular material, which can be used for modifying polyolefin resins to prepare thermoplastic E-BEB-E / polyolefin dynamically vulcanized elastic materials (TPV) and PP / E-BEB-E thermoplastic hard alloys.

[0039] The E-BEB-E provided by the present invention is prepared by a stepwise polymerization temperature control method:

[0040] Step 1: In an anionic polymerization solvent system containing an activator and a hindered amine molecular weight distribution broadening regulator, the cyclohexane solvent is heated to 80-90°C, and then a certain amount of n-butyl lithium (NBL) is added, followed by a certain amount of butadiene for homopolymerization for 20-25 minutes to form B1-Li + The active polymer B1 is mainly 1,4-polymerized units of butadiene, and also contains a small amount of 1,2-polymerized units, among which the number of 1,4-polymerized units is much greater than that of 1,2-polymerized units;

[0041] Step 2: Cool the above polymerization solution, add a certain amount of butadiene and react at 50-60°C for not less than 30 minutes. The resulting polymer exhibits a B1-B2-Li + The active polymer (BR original rubber) in the B2 segment still contains more 1,4-polymer units than 1,2-polymer units, but the content of 1,2-polymer units in the B2 segment is greater than that in the B1 segment.

[0042] Step 3: The above polymerization solution is heated, and then a certain amount of butadiene is added to react at 75-85°C for 25-35 minutes. The resulting polymer exhibits a B1-B2-B3-Li + The active polymer (BR original rubber) contains 1,4-polymer units in the B3 segment which are much larger than 1,2-polymer units.

[0043] Step 4: Add a certain amount of NBL, a co-catalyst and a titanocene catalyst to the BR original rubber solution and react at a certain temperature and hydrogen pressure for not less than 90 minutes to obtain an E-BEB-E rubber solution;

[0044] Step 5: Terminate the E-BEB-E glue solution with a small amount of water, then use dry method to devolatilize the solvent in the glue solution, and obtain E-BEB-E transparent material through pelletizing.

[0045] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0046] The E-BEB-E synthesis method of the present invention can be completed by using the existing traditional anionic polymerization and titanocene catalytic hydrogenation process, and has the advantages of short polymerization and catalytic hydrogenation time, controllable molecular weight distribution and hydrogenation degree, etc.

[0047] The present invention unexpectedly discovered that E-BEB-E can effectively control the diblock polyethylene chain segments and polyethylene / poly-1-butene random chain segments in the polymer by using a small amount of THF with weak regulating ability as a microstructure regulator and a high-low-high variable temperature polymerization technology and process, giving the polymer good elasticity and tensile strength (like the well-known block polymers such as SBS and SEBS), and can be used as a polyolefin thermoplastic elastomer, with the characteristics of good physical and mechanical properties and easy processing, and more importantly, also showing excellent heat aging resistance.

[0048] The E-BEB-E of the present invention can be used alone, or can be mixed with polyolefin resin and vulcanized by peroxide to prepare elastic alloy by extrusion molding. In addition, it can be combined with sulfur and molded by molding or microwave vulcanization.

[0049] The preparation process of E-BEB-E of the present invention belongs to homogeneous reaction, and the preparation is simple, and can be synthesized by using existing mature technology, and is easy to control and industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is the GPC spectrum of the original gum B1-B2-B3-1# prepared in Example 1.

[0051] Figure 2 H of the original rubber B1-B2-B3-1# prepared in Example 1 1 -NMR.

[0052] Figure 3 EBE-1#H prepared in Example 1 1 -NMR. DETAILED DESCRIPTION

[0053] 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.

[0054] 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 crystallinity of the hydride is determined by differential scanning calorimetry (DSC) analyzer; the mechanical properties of the raw rubber are tested according to the GB / T36089-2018 method.

[0055] Example 1

[0056] Under nitrogen protection, 3500mL of cyclohexane, 0.30mL of tetrahydrofuran (THF) and 0.45mL of DBU were added to a 5-liter polymerization kettle, and the temperature was raised to 75°C with hot water. Then, 10mL of 0.35mol / L NBL was added, and 100mL of butadiene was added for the first time. The polymerization was carried out for 25min at a maximum polymerization temperature of no more than 90°C under a nitrogen pressure of 4.0bar. Then, the polymerization kettle was cooled to 50°C, and 230mL of butadiene was added for the second time to carry out polymerization reaction for no less than 25min, during which the polymerization temperature was maintained at no more than 60°C. The polymerization solution was then heated to 80°C, and 100mL of butadiene was added for the third time to the polymerization kettle. The polymerization time was maintained for no less than 25min, and the maximum polymerization temperature was no more than 90°C, to obtain BR raw rubber. 1 -NMR and GPC spectra are attached Figure 1 and attached Figure 2 .

[0057] The glue liquid was pressed into a hydrogenation kettle with nitrogen, and 4 mL of 0.35 mol / L NBL, 4 mL of 0.02 mol / L cyclohexane solution of dimethyl phthalate and methyl o-toluate (cocatalyst), and 0.08 g of dicyclopentadiene titanium dichloride were added, and the mixture was stirred and hydrogenated for 120 min at a hydrogen pressure of 14 bar and a temperature of 75-115° C. to obtain E-BEB-E glue liquid. The hydrogenated glue liquid was then terminated with a small amount of water, and the solvent and a small amount of water were removed by dry method in a twin-screw extruder. After underwater pelletization, E-BEB-E transparent pellets (labeled as EBE-1, the unsaturation of the polymer was measured to be 0.26% (moL), and the nuclear magnetic hydrogen spectrum was shown as follows: Figure 3 , the characteristic behaviors of the polymers are shown in Tables 1 and 2.

[0058] Example 2

[0059] The relevant process conditions in Example 1 remain unchanged, except that the total amount of NBL used is changed to 12 mL, and the butadiene used for the first, second and third times is 40, 340 and 60 mL respectively.

[0060] Results The prepared polymer was designated as EBE-2, and its behavior parameters are shown in Tables 1 and 2.

[0061] Example 3

[0062] The relevant process conditions in Example 2 were kept unchanged, except that the total amount of NBL was changed to 8 mL, and the butadiene used for the first, second and third times was 140, 220 and 140 mL respectively.

[0063] Results The prepared polymer was designated as EBE-3, and its behavior parameters are shown in Tables 1 and 2.

[0064] Example 4

[0065] The relevant process conditions in Example 2 were kept unchanged, and only DBU was changed by 0.35 mL.

[0066] Results The prepared polymer was designated as EBE-4, and its behavior parameters are shown in Tables 1 and 2.

[0067] Example 5

[0068] The relevant process conditions in Example 2 were kept unchanged, and only DBU was changed by 0.50 mL.

[0069] Results The prepared polymer was designated as EBE-5, and its behavior parameters are shown in Tables 1 and 2.

[0070] Example 6

[0071] The relevant process conditions in Example 2 were kept unchanged, and only THF was changed by 0.2 mL.

[0072] Results The prepared polymer was designated as EBE-6, and its behavior parameters are shown in Tables 1 and 2.

[0073] Example 7

[0074] The relevant process conditions in Example 2 were kept unchanged, and only 0.45 mL of THF was changed.

[0075] Results The prepared polymer was designated as EBE-7, and its behavior parameters are shown in Tables 1 and 2.

[0076] Comparative Example 1

[0077] The relevant process conditions in Example 3 were kept unchanged, except that DBU was changed to 0.28 mL and NBL was changed to 7 mL.

[0078] Results The prepared polymer was designated as EBE-8, and its behavior parameters are shown in Tables 1 and 2.

[0079] Comparative Example 2

[0080] The relevant process conditions in Example 2 were kept unchanged, and only DBU was changed by 0.40 mL.

[0081] Results The monomers were fully converted after 65 min of polymerization. n 5.53×10 4 , molecular mass distribution (M w / M n )=3.25, ML / 125℃) is 14.6. The polymer is self-adhesive at room temperature and cannot be made into pellets.

[0082] Comparative Example 3

[0083] The relevant process conditions in Example 1 remain unchanged, except that 0.45 mL of THF is used.

[0084] The resulting polymer was self-adhesive at room temperature.

[0085] Comparative Example 4

[0086] The relevant process conditions in Example 10 were kept unchanged, except that the amount of THF was changed to 0.15 mL.

[0087] Results The prepared polymer had high hardness, large modulus, low raw rubber elasticity and large deformation.

[0088] Comparative Example 5

[0089] The relevant process conditions in Example 1 remain unchanged, except that the second-stage polymerization temperature is selected to be 65°C.

[0090] Results The prepared polymer was calibrated as EBE-9, with high hardness, large modulus, and low raw rubber elasticity. Its behavioral parameters are shown in Tables 1 and 2.

[0091] Table 1 Characteristic analysis of the original rubber BR and hydrogenated rubber E-BEB-E in the examples

[0092]

[0093]

[0094] Table 1 Physical and mechanical properties of E-BEB-E in the examples

[0095]

[0096] Note: (1) DOW3745P is DOW Chemical EPDM rubber.

[0097] (2) The raw rubber was pressed into sheets at 160°C and tested at 25°C.

Claims

1. A polyethylene-butene rubber, characterized in that: It has the structure of formula 1: Among them, n, m, x, y, n1, m1, x1, y1, n2, m2, x2 and y2 are the degrees of polymerization; (x+y) / (x+y+n+m)﹤0.14; (x1+y1) / (x1+y1+n1+m1)=0.35~0.60; (x2+y2) / (x2+y2+n2+m2)﹤0.14; (x+y+x1+y1+x2+y2) / (n+m+n1+m1+n2+m2+x+y+x1+y1+x2+y2)=0.20~0.40; The double bond hydrogenation rate is 99.50-99.75%.

2. The polyethylene-butene rubber according to claim 1, characterized in that: (x+y+x1+y1+x2+y2) / (n+m+n1+m1+n2+m2+x+y+x1+y1+x2+y2)=0.25~0.

30.

3. The polyethylene-butene rubber according to claim 1, characterized in that: (x+y+n+m):(x1+y1+n1+m1):(x2+y2+n2+m2)=(0.50~2.5):(3.5~5.0):(0.50~2.5).

4. A polyethylene-butene rubber according to any one of claims 1 to 3, characterized in that: Mooney viscosity ML 125 ℃ is 20~70, and the crystallinity is 12~25%.

5. The polyethylene-butene rubber according to any one of claims 1 to 3, characterized in that: Number average molecular weight M n 6.0~8.0×10 4 , molecular mass distribution M w / M n =1.3~1.

5.

6. The method for preparing a polyethylene-butene rubber according to any one of claims 1 to 5, characterized in that: In an anionic polymerization solution system containing an activator and hindered amine molecules, the temperature is first raised to 80-90°C, alkyl lithium and butadiene are added for one-stage polymerization, then the temperature is lowered to 50-60°C, butadiene is added for two-stage polymerization, and then the temperature is raised to 75-85°C, butadiene is added for three-stage polymerization. After the polymerization is completed, a catalytic hydrogenation reaction is carried out, and the hydrogenated rubber is terminated, devolatilized and pelletized to obtain.

7. The method for preparing polyethylene-butene rubber according to claim 6, characterized in that: The activator is tetrahydrofuran; the concentration of the activator in the anionic polymerization solution system is 50-100 mg / kg.

8. The method for preparing polyethylene-butene rubber according to claim 6, characterized in that: The hindered amine molecules include at least one of 1,5-diazabicyclo[5.4.0]-undec-5-ene and 1,5-diazabicyclo[4.3.0]-5-nonene; The concentration of the hindered amine molecules in the anionic polymerization solution system is 100-150 mg / kg.

9. The method for preparing polyethylene-butene rubber according to claim 6, characterized in that: The molar ratio of the alkyl lithium to the total molar amount of the butadiene monomer is 1:(6.0-8.0)×10 4 .

10. The method for preparing polyethylene-butene rubber according to any one of claims 6 to 9, characterized in that: The time for the first stage polymerization is 20 to 25 minutes, the time for the second stage polymerization is not less than 30 minutes, and the time for the third stage polymerization is 25 to 35 minutes.

11. A method for preparing polyethylene-butene rubber according to any one of claims 6 to 9, characterized in that: The conditions of the catalytic hydrogenation reaction are: using active lithium as an activator, adopting a titanium-based catalyst system, a hydrogen pressure of 13 to 16 bar, a temperature of 75 to 110° C., and a time of not less than 90 minutes.

12. The method for preparing polyethylene-butene rubber according to claim 11, characterized in that: The titanium-based catalyst system comprises a main catalyst of dicyclopentadiene titanium dichloride and a co-catalyst of dimethyl phthalate and / or methyl o-toluate; the molar ratio of the main catalyst to the co-catalyst is (3-8):

1.

13. The method for preparing polyethylene-butene rubber according to claim 11, characterized in that: The molar ratio of the active lithium to the main catalyst is (6-12):1.

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