A polyethylene-butene rubber and a method for producing the same

Abstract

This invention discloses a polyethylene-butene rubber and its preparation method, belonging to the field of rubber. The polyethylene-butene rubber has a triblock structure, with polyethylene segments at both ends and polyethylene / poly-1-butene random segments with a high side group content in the middle. Its special structure gives the rubber good elasticity and tensile strength, making it suitable for use as a polyolefin thermoplastic elastomer. It possesses good physical and mechanical properties, is easy to process, and, more importantly, exhibits excellent resistance to heat aging. This E-BEB-E can be used to modify polyolefin resins to prepare thermoplastic E-BEB-E / polyolefin elastomers (TPV) and PP / E-BEB-E thermoplastic hard alloys.

Description

Technical Field

[0001] This invention relates to a polyethylene-butene rubber and its preparation method, belonging to the field of novel rubber materials technology. Background Technology

[0002] Traditional commercially available ethylene propylene rubber (EPDM) is a copolymer of ethylene, propylene and diene. Based on its different molecular structure characteristics, it has more than 20 types of applications and product models.

[0003] The ethylene-propylene ratio in EPDM can be changed during the polymerization stage. When the ethylene-propylene ratio changes from 50 / 50 to 80 / 20, the positive effects include higher compact strength, higher tensile strength, higher crystallinity, higher glass transition temperature, the ability to convert the raw polymer into granules, and better extrusion characteristics. The negative effects include poor calendering and mixing properties, poor low-temperature characteristics, and lower compression set. A higher propylene ratio results in better processability, improved low-temperature characteristics, and higher compression set. The molecular weight of EPDM is usually expressed as Mooney viscosity. The Mooney viscosity value for EPDM is obtained at a high temperature of 125°C, primarily to eliminate crystallization caused by high ethylene content, as crystallization masks the true molecular weight of the polymer. The Mooney viscosity of EPDM ranges from 20 to 100. Its molecular weight distribution index varies between 2 and 5. Increasing molecular weight distribution improves mixing and milling processability. However, a narrower molecular weight distribution can improve vulcanization rate, vulcanization state, and injection molding behavior. EPDM can be vulcanized using peroxides or sulfur. However, compared to sulfur vulcanization, peroxide-crosslinked EPDM has higher temperature resistance, lower compression set, and improved vulcanization properties when used in the wire and cable industry.

[0004] The journal *Thermoplastic Elastomers* reviewed 99 rubber / plastic blends prepared from 11 types of rubber and 9 types of plastic. The study found that to obtain dynamically vulcanized rubber / thermoplastic plastic blends with optimal performance, the surface energies of the two polymers must be matched, the rubber should have a low entanglement chain length, and the plastic should have a crystallinity greater than 15%. When there is a significant difference in polarity or surface energy between the plastic and rubber, adding a suitable compatibilizer before dynamic vulcanization can also yield high-performance blends. Commercially available dynamically vulcanized thermoplastic elastomers (TPVs) can be formed between PP / PE / EPDM and PP / EPDM, accounting for 90% of all TPVs. This is mainly due to the better compatibility between PP and EPDM, the relatively mature vulcanization systems available for EPDM, and EPDM's excellent weather resistance, resulting in a moderate raw material cost. Ethylene propylene diene monomer (EPDM / PP) is a product made by compounding EPDM with PP, while simultaneously achieving the desired degree of crosslinking in the EPDM. Not only does it retain the inherent properties of EPDM, but it also has significant process properties similar to those of thermoplastics in injection molding, extrusion, blow molding, and calendering.

[0005] However, existing EPDM and PP / EPDM dynamically vulcanized thermoplastic elastomers all suffer from large compression set, poor calendering compatibility, and poor low-temperature performance. Improving and overcoming these shortcomings to create vulcanized rubber and plastic materials with high strength, moderate crystallinity, good compatibility with PP, excellent aging resistance, low deformation, high modulus, and resilience is a current aspiration for a better life. Summary of the Invention

[0006] The existing EPDM and PP / EPDM dynamic vulcanized thermoplastic elastomers have the following drawbacks: large compression deformation, poor calendering and mixing properties, and poor low-temperature performance. In addition, polyethylene-butene rubber has not yet been industrialized.

[0007] The first objective of this invention is to provide a polyethylene-butene rubber (E-BEB-E for short), wherein the ends of the rubber are mainly composed of polyethylene segments, while the middle is composed of polyethylene / poly-1-butene random segments with a high content of side groups. Its special structure gives the rubber good elasticity and tensile strength (like block polymers such as SBS and SEBS), and it can be used as a polyolefin thermoplastic elastomer. It has good physical and mechanical properties, is easy to process, and, more importantly, exhibits excellent resistance to heat aging. This E-BEB-E can be used to modify 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 objective of this invention is to provide a method for preparing polyethylene-butene rubber. This method uses solution polymerization to synthesize the rubber, which is simple, low-cost, and can be produced using existing mature equipment and processes, making it easy to industrialize.

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

[0010]

[0011] in,

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

[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 this invention refers to the molar percentage of hydrogenated butadiene units in the total butadiene units.

[0019] The E-BEB-E rubber of this invention is obtained by hydrogenation of polybutadiene obtained by anionic polymerization, with a hydrogenation rate of 99.5% to 99.75%. The remaining small amount of double bonds can be used for crosslinking and vulcanization. E-BEB-E has a triblock structure, with its two ends being polybutadiene with a high proportion of 1,4-polymerization. After hydrogenation, it mainly forms polyethylene blocks, i.e., E blocks, which have relatively high crystallinity. The middle segment is polybutadiene with a high proportion of 1,2-polymerization. After hydrogenation, it mainly forms polyethylene / poly1-butene random blocks, i.e., BEB blocks, which have very low crystallinity and soft segment properties. The E blocks in the E-BEB-E rubber molecule provide physical crosslinking points for the polymer, giving the polymer high tensile strength, while the BEB blocks endow the polymer with good flexibility, high resilience, and other properties. Furthermore, the trace double bonds provide chemical vulcanization crosslinking points for the polymer. The vulcanized polymer forms a network macromolecule with a certain elastic modulus, improving the overall physical properties of the macromolecule. In particular, when combined with polyolefin resin, it produces good flexibility, high resilience, high elastic modulus, low compression deformation, and anti-aging properties.

[0020] As a preferred solution, (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 embodiment, (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 two E-blocks in the E-BEB-E rubber of this invention... n (0.50~2.5)×10 4 If its molecular weight is too low, the crystallinity is too low, and the tensile strength of the polymer is too low. If its molecular weight is too high, the BEB molecular chains exhibit a disordered distribution. If the molecular weight is too low, the polymer modulus increases, but the elasticity decreases. The molecular weight M of the intermediate BEB block is... n (3.5~5.0)×10 4 .

[0022] As a preferred option, Mooney viscosity ML 125℃The Mooney viscosity ranges from 20 to 70, with a crystallinity of 12% to 25%. Typically, the Mooney viscosity of rubber is measured at 100°C / (1+4 min). The E-BEB-E molecules of this invention contain highly isotactic E blocks, exhibiting relatively high crystallinity. Furthermore, the polymer molecules are not completely randomized, failing to accurately reflect the molecular weight of the polymer (Mouney viscosity corresponds to molecular weight). Therefore, the Mooney viscosity of the polymer in this invention is measured at 125°C / (1+4 min) to eliminate the crystallinity and cohesive energy of the polymer. If the Mooney viscosity is too high, melt fracture will occur during extrusion blending with polyolefin resin, resulting in defects in the product. Therefore, it is more suitable if the melting temperatures of the polyolefin polymer and the polyolefin are not significantly different.

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

[0024] As a preferred embodiment, the number-average molecular weight M of the E-BEB-E is... n The value is 6.0 to 8.0 × 10⁻⁶. 4 .

[0025] The present invention also provides a method for preparing polyethylene-butene rubber. The method involves first heating the solution to 80-90°C, adding alkyl lithium and butadiene for a first-stage polymerization, then cooling the solution to 50-60°C and adding butadiene for a second-stage polymerization, then heating the solution to 75-85°C and adding butadiene for a third-stage polymerization. After polymerization, a catalytic hydrogenation reaction is carried out, and the hydrogenated rubber solution is terminated, devolatilized, and pelletized to obtain the final product.

[0026] In the preparation process of the polyethylene-butene rubber of the present invention, high-temperature polymerization is used in the first-stage and three-stage polymerization to generate more 1,4-polymer structures, which facilitates the generation of longer polyethylene blocks after hydrogenation. Low-temperature polymerization is used in the second-stage polymerization to generate more 1,2-polymer structures, which facilitates the generation of more ethyl side chains after hydrogenation. This increases the disordered distribution of hydrogenated polyethylene and poly-1-butene and the overall elasticity of the polymer.

[0027] As a preferred embodiment, the activator is tetrahydrofuran. More 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 of styrene-butadiene polymers (SBS). For example, the 1,2-polymer structure in the butadiene segments of commercially available SBS molecules is no higher than 14%. Higher THF content results in higher 1,2-polymer structure content, and lower THF content results in lower 1,2-polymer structure content. Furthermore, higher polymerization temperature results in lower 1,2-polymer structure content, and lower polymerization temperature results in higher 1,2-polymer structure content. The polymerization mechanism of Lewis bases used in anionic polymerization, such as regulators or activators, is the same; the only difference is the varying regulatory capacity of different Lewis bases. Among Lewis bases, THF has the weakest regulatory capacity, but it is beneficial for preparing higher-content 1,4-adducts such as SBS. This explains why the present invention employs high-temperature polymerization in the first and third stages to generate more 1,4-polymer structures, facilitating the formation of longer polyethylene blocks after hydrogenation, and low-temperature polymerization in the second stage to generate more 1,2-polymer structures, facilitating the formation of more ethyl side chains after hydrogenation, thereby increasing the disordered distribution of hydrogenated polyethylene and poly-1-butene and the overall elasticity of the polymer. Furthermore, hindered amine molecules, being Lewis bases, also have a moderating function, slowing down the polymerization rate and broadening the molecular weight distribution of the polymer, as described in (US4451576A). The present invention uses THF as the initiating activator, ensuring that the probability of 1,2-polymerization of butadiene is less than 14%, thus maximizing the 1,4-polymerization of butadiene. After hydrogenation, this results in the formation of E blocks containing more than 86% polyethylene.

[0028] As a preferred embodiment, the hindered amine molecule includes 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 molecule in the anionic polymerization solution system is 100-150 mg / kg.

[0029] As a preferred embodiment, the total molar ratio of alkyllithium to butadiene is 1:(6.0~8.0)×10. 4 .

[0030] As a preferred approach, the polymerization time is 20–25 min for the first stage, at least 30 min for the second stage, and 25–35 min for the third stage. Higher temperatures in the first and third stages result in a higher proportion of 1,4-addition to butadiene, facilitating the formation of isotactic polyethylene blocks (E) after hydrogenation. The second stage polymerization temperature should be slightly lower to encourage 1,2-polymerization of butadiene, preventing the formation of polyethylene segments due to excessive hydrogenation of butadiene 1,4-polymer units, which would cause the polymer to lose elasticity. In other words, during the synthesis of the original rubber, this polymer block should have a quantitative amount of 1,2-polymer units and 1,4-polymer units arranged randomly for the hydrogenated polymer to exhibit rubber-like behavior. Therefore, the second stage polymerization should be carried out at a low temperature for a period of time to produce a quantitative amount of random copolymer soft segments of 1,2-polymer units and 1,4-polymer units, with a polymerization time of at least 30 min.

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

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

[0033] As a preferred embodiment, the molar ratio of the active lithium to the main catalyst is (6–12):1. Preferred active lithium types include alkyl lithium, such as n-butyllithium.

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

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

[0036] As a preferred option, the termination is performed using water.

[0037] As a preferred embodiment, the volatile matter removal process employs a twin-screw extruder to remove volatiles.

[0038] The E-BEB-E of this invention is a transparent granular material that can be used to modify polyolefin resins to prepare thermoplastic E-BEB-E / polyolefin dynamically vulcanized elastic material (TPV) and PP / E-BEB-E thermoplastic hard alloy.

[0039] The E-BEB-E provided by this invention is prepared using a segmented controlled polymerization temperature method:

[0040] Step 1: In an anionic polymerization solvent system containing an activator and a hindered amine molecular weight distribution broadening modifier, the cyclohexane solvent is heated to 80–90°C, then a measured amount of n-butyllithium (NBL) is added, followed by a measured amount of butadiene to carry out a homopolymerization reaction for 20–25 min, forming B1-Li. + The living polymer, B1, is mainly composed of 1,4-polymer units of butadiene, and also contains a small amount of 1,2-polymer units. The number of 1,4-polymer units is much greater than that of 1,2-polymer units.

[0041] Step 2: Cool the above polymerization solution, then add a measured amount of butadiene and react at 50-60°C for at least 30 minutes. The resulting polymer exhibits a B1-B2-Li composition. + The active polymer (BR raw gum) contains more 1,4-polymer units in segment B2 than 1,2-polymer units; it's just that the content of 1,2-polymer units in segment B2 is greater than that in segment B1.

[0042] Step 3: Heat the above polymerization solution, then add a measured amount of butadiene and react at 75-85°C for 25-35 minutes. The resulting polymer exhibits a B1-B2-B3-Li composition. + The active polymer (BR gel) contains far more 1,4-polymer units than 1,2-polymer units in segment B3;

[0043] Step 4: Add a certain amount of NBL, co-catalyst, and titanium holocata to the BR raw rubber solution and react for no less than 90 minutes under a certain temperature and hydrogen pressure to obtain E-BEB-E solution.

[0044] Step 5: Stop the E-BEB-E adhesive solution with a small amount of water, then use a dry method to evaporate the solvent in the adhesive solution, and then granulate to obtain E-BEB-E transparent material.

[0045] Compared with existing technologies, the beneficial effects of the technical solution of this invention are as follows:

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

[0047] This 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 through a small amount of THF with weak regulatory ability as a microstructure regulator and high-low-high temperature variable polymerization technology and process. This gives the polymer good elasticity and tensile strength (like well-known block polymers such as SBS and SEBS), and it can be used as a polyolefin thermoplastic elastomer. It has good physical and mechanical properties, is easy to process, and, more importantly, exhibits excellent heat aging resistance.

[0048] The E-BEB-E of the present invention can be used alone, or it can be blended with polyolefin resin and prepared into an elastic alloy by peroxide vulcanization and then extruded. Alternatively, it can be combined with sulfur and molded or microwave vulcanized.

[0049] The E-BEB-E 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

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

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

[0052] Figure 3 EBE-1#H prepared in Example 1 1 -NMR. Detailed Implementation

[0053] 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.

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

[0055] Example 1

[0056] Under nitrogen protection, 3500 mL of cyclohexane, 0.30 mL of tetrahydrofuran (THF), and 0.45 mL of DBU were added to a 5 L polymerization reactor. The mixture was heated to 75 °C with hot water, and then 10 mL of 0.35 mol / L NBL was added. 100 mL of butadiene was added initially, and polymerization was carried out for 25 min at a nitrogen pressure of 4.0 bar and a maximum temperature not exceeding 90 °C. The polymerization reactor was then cooled to 50 °C, and 230 mL of butadiene was added for the second time, with the polymerization reaction continuing for at least 25 min, maintaining the polymerization temperature not exceeding 60 °C. The polymerization solution was then heated to 80 °C, and 100 mL of butadiene was added again for the third time, maintaining the polymerization time at at least 25 min and the maximum polymerization temperature not exceeding 90 °C to obtain the BR raw rubber. The H of the raw rubber BR... 1 -NMR and GPC spectra are attached. Figure 1 and attached Figure 2 .

[0057] The adhesive solution was pressurized into a hydrogenation reactor under nitrogen pressure, and 4 mL of 0.35 mol / L NBL, 4 mL of a cyclohexane solution of 0.02 mol / L dimethyl phthalate and methyl o-methyl benzoate (co-catalyst), and 0.08 g of dicyclopentadiene titanium dichloride were added. 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 the E-BEB-E adhesive solution. The hydrogenated adhesive solution was then terminated with a small amount of water, and the solvent and a small amount of water were removed by dry extrusion on a twin-screw extruder. After underwater pelletizing, transparent E-BEB-E granules were obtained (labeled as EBE-1; the polymer unsaturation was measured to be 0.26% (mol / L); the 1H NMR spectrum is shown below). Figure 3 The characteristic behaviors of the polymers are shown in Tables 1 and 2.

[0058] Example 2

[0059] Keeping the relevant process conditions in Example 1 unchanged, only the total amount of NBL used was changed to 12 mL, and the butadiene used in the first, second and third times was 40, 340 and 60 mL respectively.

[0060] The resulting polymer was labeled EBE-2, and its behavioral parameters are shown in Tables 1 and 2.

[0061] Example 3

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

[0063] The resulting polymer was labeled EBE-3, and its behavioral parameters are shown in Tables 1 and 2.

[0064] Example 4

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

[0066] The resulting polymer was labeled EBE-4, and its behavioral parameters are shown in Tables 1 and 2.

[0067] Example 5

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

[0069] The resulting polymer was labeled EBE-5, and its behavioral parameters are shown in Tables 1 and 2.

[0070] Example 6

[0071] The relevant process conditions in Example 2 were kept unchanged, except that the amount of THF was changed by 0.2 mL.

[0072] The resulting polymer was labeled EBE-6, and its behavioral parameters are shown in Tables 1 and 2.

[0073] Example 7

[0074] The relevant process conditions in Example 2 were kept unchanged, except that the amount of THF was changed to 0.45 mL.

[0075] The resulting polymer was labeled EBE-7, and its behavioral 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 0.28 mL and NBL was 7 mL.

[0078] The resulting polymer was labeled EBE-8, and its behavioral parameters are shown in Tables 1 and 2.

[0079] Comparative Example 2

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

[0081] The monomer polymerization took 65 minutes to complete, and the prepared polymer M was obtained. n It is 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 granules.

[0082] Comparative Example 3

[0083] The relevant process conditions in Example 1 were kept unchanged, except that the amount of THF used was changed to 0.45 mL.

[0084] The resulting polymer is 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 used was changed to 0.15 mL.

[0087] The resulting polymer exhibited high hardness, high modulus, low raw rubber elasticity, and large deformation.

[0088] Comparative Example 5

[0089] The relevant process conditions in Example 1 were kept unchanged, except that the two-stage polymerization temperature was set to 65°C.

[0090] The prepared polymer, labeled EBE-9, exhibits high hardness, high modulus, and low raw rubber elasticity. Its behavioral parameters are shown in Tables 1 and 2.

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

[0092]

[0093]

[0094] Table 1 shows the physical and mechanical properties of E-BEB-E in the embodiments.

[0095]

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

[0097] (2) Raw rubber was pressed into tablets at 160℃ and tested at 25℃.

Claims

1. A polyethylene-butene rubber, characterized in that: It has the structure of Formula 1: Where n, m, x, y, n1, m1, x1, y1, n2, m2, x2, and y2 are all 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 The temperature ranges from 20 to 70 degrees Celsius, and the crystallinity ranges from 12 to 25%.

5. A polyethylene-butene rubber according to any one of claims 1 to 3, characterized in that: Number-average molecular weight M n The value is 6.0 to 8.0 × 10⁻⁶. 4 Molecular mass distribution M w / M n =1.3~1.

5.

6. A 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 activators and hindered amine molecules, the temperature is first raised to 80-90°C, and alkyllithium and butadiene are added for a first-stage polymerization. Then the temperature is lowered to 50-60°C, and butadiene is added for a second-stage polymerization. The temperature is then raised to 75-85°C, and butadiene is added for a third-stage polymerization. After polymerization is completed, a catalytic hydrogenation reaction is carried out. The hydrogenated gel is then terminated, devolatilized, and pelletized to obtain the final product.

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 total molar ratio of the alkyllithium to the butadiene monomer is 1:(6.0~8.0)×10. 4 .

10. A method for preparing polyethylene-butene rubber according to any one of claims 6 to 9, characterized in that: The time for the first stage of polymerization is 20-25 minutes, the time for the second stage of polymerization is no less than 30 minutes, and the time for the third stage of polymerization is 25-35 minutes.

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

12. The method for preparing polyethylene-butene rubber according to claim 11, characterized in that: The titanium-based catalytic system comprises a dicyclopentadiene titanium dichloride main catalyst and dimethyl phthalate and / or methyl o-methylbenzoate co-catalysts; 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 active lithium to the main catalyst is (6-12):1.

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