Catalyst for the preparation of polyethylene elastomers, polyethylene elastomers and methods and uses thereof

Abstract

In the present application, the catalyst for preparing polyethylene elastomer, ethylene and co-catalyst are dispersed in organic solvent to carry out polymerization treatment to obtain polyethylene elastomer. The catalyst for preparing polyethylene elastomer provided by the present application is cheap and easy to obtain. The catalyst has a specific molecular structure. In the process of preparing polyethylene elastomer, the unique steric hindrance and electronic effect of the catalyst make it exhibit excellent catalytic activity. The prepared polyethylene elastomer has excellent elasticity and mechanical properties while improving the branching degree and narrow molecular weight distribution. The polyethylene elastomer can be widely applied in the fields of automobile, photovoltaic, medical treatment, packaging and the like to meet the use requirements of high-performance polyethylene elastomer in these fields.

Description

Technical Field

[0001] This application relates to the field of polyolefins, and more specifically, to a catalyst for preparing polyethylene elastomers, polyethylene elastomers, methods for preparing the same, and their applications. Background Technology

[0002] Polyolefin elastomers (POEs) are a class of random copolymers formed by copolymerizing ethylene with α-olefins (such as 1-butene, 1-hexene, and 1-octene). They combine thermoplastic processability with rubber elasticity and are widely used in automotive, photovoltaic, medical, and packaging industries. Traditional POEs mainly rely on metallocene catalysts (such as CGC-type catalysts) to achieve efficient copolymerization of ethylene and α-olefins, and their performance regulation mainly depends on adjusting the type and content of comonomers.

[0003] However, the branched structure of traditional POE is relatively regular and the branching density is limited, making it difficult to meet the comprehensive requirements of high-performance elastomers for "high elasticity, high toughness, and wide temperature range". In recent years, researchers have found that increasing the branching degree of the polyolefin backbone (especially the branching density of short chains) can significantly reduce crystallinity and improve chain segment mobility, thereby endowing the material with better elasticity, transparency, and low-temperature toughness.

[0004] In 2020, the team led by Jian Zhongbao at the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, developed a space-confined α-diimine Pd catalyst, which enabled the preparation of polyethylene elastomers with a branching degree as high as 220 / 1000C, and exhibited living polymerization characteristics with a molecular weight of over 1.5 million.

[0005] The key to achieving high branching is to construct a "chain-walking" polymerization mechanism, that is, the catalyst continuously migrates along the main chain during the polymerization process, resulting in repeated insertion of ethylene monomers to form branches. The current mainstream strategies include: (1) preparing catalysts such as α-diimine Ni / Pd complexes through a post-transition metal strategy, with a branching degree of 100~220 / 1000C. This strategy has the characteristic that a single ethylene system can be highly branched without the need for α-olefins; (2) preparing metallocene + ZN composite catalysts through a cascade polymerization strategy, with a controllable branching degree range. This strategy has the characteristic of being able to construct complex topological structures such as comb and star; (3) preparing Pd-based active catalysts through an active and controllable polymerization strategy, with a molecular weight >1.5 million and PDI <1.5. These catalysts have the characteristics of uniform branching, controllable structure, and suitability for precision functional materials.

[0006] Highly branched polyolefin elastomers refer to polyolefin materials with a main chain branching degree exceeding 100 branches per 1000 carbon atoms. Their branches are predominantly short chains such as methyl, ethyl, and butyl, exhibiting a highly random distribution and almost completely inhibiting crystallization. Due to their excellent comprehensive properties, highly branched polyolefin elastomers have become key candidate materials for high-end applications such as photovoltaic encapsulation films, flexible cables, medical catheters, and hot melt adhesive films. However, their large-scale application still faces the following challenges: High catalyst cost: Post-transition metal catalysts (such as Pd and metallocene) are expensive, and their activity is sensitive to oxygen / water; Unclear structure-activity relationship: Quantitative models relating branching distribution, chain topology, and macroscopic properties have not yet been established; Limited core technology: Core catalysts and polymerization processes still rely on imports, and domestic production urgently requires breakthroughs in key issues that need to be addressed in this field.

[0007] In view of the above, this application is hereby submitted. Summary of the Invention

[0008] The main objective of this application is to provide a catalyst for preparing polyethylene elastomers, polyethylene elastomers, their preparation methods and applications, in order to solve the problems of high-temperature deactivation, insufficient branching degree and high cost of polyethylene elastomers in the prior art.

[0009] To achieve the above objectives, according to one aspect of this application, a catalyst for preparing polyethylene elastomers is provided, the catalyst having a structure as shown in Formula I or Formula II:

[0010] Formula I

[0011] Formula II

[0012] Wherein, R1~R10 are each independently selected from H, substituted or unsubstituted C1~C4 alkyl groups; a, c, d, f are each independently an integer between 1 and 4; b, e are each independently an integer between 1 and 2; g, j are each independently an integer between 1 and 3; h and i are each independently an integer between 1 and 6; X is selected from halogens.

[0013] Furthermore, R 1 ~R 10 Each is independently selected from H, substituted or unsubstituted C1 to C4 alkyl groups; a, c, d, f are each independently 1, 2, 3 or 4; b, e are each independently 1 or 2; g, j are each independently 1, 2 or 3; h, i are each independently 1, 2, 3, 4, 5 or 6; X is selected from Cl and Br.

[0014] Furthermore, the catalyst has the structures shown in formulas (I-1), (I-2), (II-1), and (II-2):

[0015] Equation (Ⅰ-1)

[0016] Equation (Ⅰ-2)

[0017] Equation (Ⅱ-1)

[0018] Equation (Ⅱ-2).

[0019] To achieve the above objectives, according to a second aspect of this application, a method for preparing a polyethylene elastomer is provided, the method comprising: dispersing the catalyst, ethylene and co-catalyst provided in the first aspect of this application in an organic solvent for polymerization treatment to obtain a polyethylene elastomer.

[0020] Furthermore, the preparation method includes first dispersing the catalyst, ethylene, and co-catalyst in an organic solvent for polymerization treatment to obtain a polyethylene adhesive; then quenching and deashing the polyethylene adhesive, followed by extrusion granulation to obtain a masterbatch-type polyethylene elastomer.

[0021] Furthermore, the polymerization temperature is 30~85℃, the polymerization pressure is 1~6MPa, the polymerization time is 20~50min, and the water content of the polymerization system is ≤20ppm.

[0022] Furthermore, the mass-to-volume ratio of ethylene to organic solvent is (0.5~2):(2~10) kg / L.

[0023] Furthermore, the mass ratio of ethylene to catalyst is (10000~25000):1.

[0024] Furthermore, the organic solvent is a compound solvent of aromatic hydrocarbon solvents and alkane solvents.

[0025] Furthermore, the volume ratio of aromatic hydrocarbon solvents to alkane solvents is 1:(100~200).

[0026] Furthermore, the aromatic hydrocarbon solvent is selected from at least one of benzene, toluene, and xylene.

[0027] Furthermore, the alkane solvent is selected from at least one of n-heptane, n-hexane, isooctane, isobutane, n-pentane, isopentane, methylcyclopentane, and methylcyclohexane.

[0028] Furthermore, the co-catalyst is selected from at least one of triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum chloride, dichloroethylaluminum, methylaluminoxane, and modified methylaluminoxane.

[0029] Furthermore, the molar ratio of aluminum to nickel in the co-catalyst is (600~3000):1.

[0030] According to a third aspect of this application, a polyethylene elastomer is provided, which is prepared according to the preparation method provided in the second aspect of this application.

[0031] Furthermore, the degree of branching of the polyethylene elastomer is 70~130 branches / 1000C, and the PDI is 1.84~2.06.

[0032] According to a fourth aspect of this application, an application of a polyethylene elastomer in the automotive, photovoltaic, medical, and packaging fields is provided. The polyethylene elastomer is either a polyethylene elastomer prepared by the preparation method provided in the second aspect of this application or a polyethylene elastomer provided in the third aspect of this application.

[0033] The catalyst provided in this application for preparing polyethylene elastomers is inexpensive and readily available. This catalyst possesses a specific molecular structure, and its unique steric hindrance and electronic effects during the preparation of polyethylene elastomers result in excellent catalytic activity. The prepared polyethylene elastomer exhibits excellent elasticity and mechanical properties while improving branching degree and narrowing molecular weight distribution. This polyethylene elastomer can be widely used in automotive, photovoltaic, medical, and packaging fields, meeting the demand for high-performance polyethylene elastomers in these industries. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the embodiments.

[0035] As described in the background section of this application, existing technologies suffer from problems such as high-temperature deactivation of polyethylene elastomers, insufficient branching, and high cost. To address these issues, this application provides a catalyst for preparing polyethylene elastomers, a polyethylene elastomer, a method for preparing the same, and its applications.

[0036] In a first typical embodiment of this application, a catalyst for preparing polyethylene elastomers is provided, the catalyst having a structure as shown in Formula I or Formula II:

[0037] Formula I

[0038] Formula II

[0039] Among them, R 1 ~R 10Each is independently selected from H, substituted or unsubstituted C1-C4 alkyl groups; a, c, d, f are each independently integers between 1 and 4; b, e are each independently integers between 1 and 2; g, j are each independently integers between 1 and 3; h and i are each independently integers between 1 and 6; X is selected from halogens.

[0040] The catalyst for preparing polyethylene elastomers provided in this application is inexpensive and readily available. This catalyst possesses a specific molecular structure, and its unique steric hindrance and electronic effects result in excellent catalytic activity during the preparation of polyethylene elastomers. The prepared polyethylene elastomer exhibits excellent elasticity and mechanical properties while simultaneously improving branching degree and narrowing molecular weight distribution. This polyethylene elastomer can be widely used in automotive, photovoltaic, medical, and packaging fields, meeting the demand for high-performance polyethylene elastomers in these industries.

[0041] In this application, when R 1 ~R 10 When each of the groups is a substituent, the substituent is selected from C1 to C4 alkyl, phenyl, or halogen, wherein the alkyl group is selected from at least one of methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, sec-butyl, and tert-butyl.

[0042] In this application, all the above-mentioned catalysts are commercially available. All of the above-mentioned catalysts can be prepared by the following steps:

[0043] Step (1): A mixture of 4-dimethylaniline (5.36 g, 50 mmol) and 4,4'-difluorodiphenylmethanol (22.02 g, 100 mol) was placed in a single-necked round-bottom flask and heated at 140 °C to melt it into a brown melt. A hydrochloric acid solution containing zinc chloride (1.34 g, 10 mmol) was added dropwise to the reaction flask, and the reaction was carried out for 5 hours until the reaction mixture was completely solid and no more water was formed. After the reaction flask cooled, the reaction mixture was completely dissolved in dichloromethane and extracted and washed successively with saturated ammonium chloride aqueous solution and saturated sodium chloride aqueous solution. After extraction, the organic phase solution was collected and dried over anhydrous magnesium sulfate. After filtration, some organic solvent was removed under reduced pressure, and the product was recrystallized from the product with an appropriate amount of ethanol (50-100 mL) to obtain product A as a white powder (16.88 g, 66%).

[0044] Step (2): Dissolve acenaphthene (1.60 g, 8.8 mmol) and p-toluenesulfonic acid (0.28 g, approximately 20 mol%) in excess methanol to obtain a suspension. After stirring the suspension for half an hour, add a solution of dichloromethane (20 mL) containing aniline A (4.09 g, 8.0 mmol) dropwise to the suspension over 1 hour using a dropping funnel, and then stir at room temperature for 1-2 hours. During the reaction, stop the reaction when the aniline feedstock is basically consumed by TLC. Add the appropriate amount of triethylamine (1.00 g, 10 mmol) to the mixture under ice-water bath and stop the reaction to obtain a mixed solution. Let the mixed solution stand and filter. Concentrate the filtrate to approximately 5 mL on a rotary evaporator and recrystallize it with a large amount of methanol (100 mL) to obtain an orange solid product B (4.70 g, 87%).

[0045] Step (3): A mixture of reactant B (2.50 g, 3.60 mmol), 2,6-diethyl-4-methylaniline (0.59 g, 3.96 mmol), and zinc chloride (0.49 g, 3.60 mmol) was uniformly dissolved in acetic acid (8 mL, approximately 30 mmol). The reaction mixture was refluxed under stirring for 4 hours. When the mixture was gradually cooled to room temperature, a distinct red solid was observed to precipitate. The suspension was then washed with diethyl ether (3 × 10 mL) and the solid was separated by filtration. The solid was dried under vacuum to obtain a bright red, insoluble solid, namely the zinc diimide complex. The zinc diimide complex obtained above was completely dissolved in dichloromethane (30 mL), and a sufficient amount of aqueous solution containing potassium carbonate (1.38 g, 10 mmol) (20 mL) was added. After stirring for 2 hours, a white flocculent substance was observed to form at the interface between the two phases. The resulting organic phase was extracted two to three times with deionized water, dried with anhydrous magnesium sulfate, and concentrated to 5 mL using a rotary evaporator. Recrystallization with methanol (25 mL) yielded 1.8 g of orange powder product C, with a yield of 61%.

[0046] Step (4): Under nitrogen atmosphere, ligand C, (DME)NiBr2 was added in the same equivalent (2 mmol) and dissolved in dichloromethane (10 mL). The mixture was stirred at room temperature for 12 hours. After the reaction was completed, the solvent was concentrated to about 2 mL under reduced pressure using cold hydrazine. Then, an appropriate amount of diethyl ether (10 mL) was added, and a red precipitate was formed. The precipitate was washed three times with diethyl ether (3 × 10 mL). After filtration and drying, the resulting red powder was catalyst D, with a yield of approximately 90%.

[0047] In some embodiments, R 1 ~R 10Each of the following components is independently selected from H, substituted or unsubstituted C1-C4 alkyl groups; a, c, d, and f are each independently 1, 2, 3, or 4; b and e are each independently 1 or 2; g and j are each independently 1, 2, or 3; h and i are each independently 1, 2, 3, 4, 5, or 6; and X is selected from Cl and Br. By optimizing the structure of the catalyst, the steric hindrance and electronic effects of the catalyst can be further optimized, thereby enabling the catalyst to exhibit excellent catalytic activity.

[0048] In some preferred embodiments, the catalyst has a structure as shown in formulas (I-1), (I-2), (II-1), and (II-2):

[0049] Equation (Ⅰ-1)

[0050] Equation (Ⅰ-2)

[0051] Equation (Ⅱ-1)

[0052] Equation (Ⅱ-2).

[0053] The catalyst employing the aforementioned structures can further ensure its catalytic activity during the preparation of polyethylene elastomers. These structures not only effectively increase the specific surface area of ​​the catalyst but also enhance the exposure of active sites, which is beneficial for the polymerization reaction of ethylene monomers. Furthermore, by optimizing the catalyst structure, precise control over the polymer molecular weight distribution, comonomer distribution, and polyethylene elastomer properties can be achieved, thereby producing polyethylene elastomer materials with excellent comprehensive performance.

[0054] In a second typical embodiment of this application, a method for preparing a polyethylene elastomer is provided. The method includes dispersing the catalyst, ethylene, and co-catalyst provided in the first typical embodiment of this application in an organic solvent for polymerization treatment to obtain a polyethylene elastomer. The polyethylene elastomer obtained by the above preparation method can achieve efficient polymerization of ethylene, and the prepared polyethylene elastomer has good elasticity and mechanical properties, meeting the application requirements of various high-performance materials.

[0055] In some embodiments, the preparation method of polyethylene elastomer includes first dispersing a catalyst, ethylene, and a co-catalyst in an organic solvent for polymerization to obtain a polyethylene adhesive; then quenching and deashing the polyethylene adhesive, followed by extrusion granulation to obtain a masterbatch-type polyethylene elastomer. By fully dispersing the catalyst, ethylene, and co-catalyst in an organic solvent, the polymerization reaction can proceed more effectively, resulting in a polyethylene elastomer with a uniform molecular structure and narrow molecular weight distribution, thereby improving the purity and performance stability of the product. Quenching and deashing the obtained polyethylene adhesive effectively removes residual catalyst and byproducts from the reaction, reducing impurity content and thus improving the purity and mechanical properties of the polyethylene elastomer. The subsequent extrusion granulation yields a masterbatch-type polyethylene elastomer, which is beneficial for subsequent processing to meet applications in various fields such as automotive, photovoltaic, medical, and packaging.

[0056] In some embodiments, the polymerization temperature is 30–85°C, the polymerization pressure is 1–6 MPa, the polymerization time is 20–50 min, and the water content of the polymerization system is ≤20 ppm. By further controlling the temperature, pressure, and polymerization time, the efficiency of the polymerization reaction can be significantly improved, and side reactions and energy consumption can be reduced. Specifically, the polymerization temperature is any value or a range between any two of 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, and 85℃; the polymerization pressure is any value or a range between any two of 1MPa, 2MPa, 3MPa, 4MPa, 5MPa, and 6MPa; the polymerization time is any value or a range between any two of 20min, 25min, 30min, 35min, 40min, 45min, and 50min; and the water content of the polymerization system is any value or a range between any two of 1ppm, 3ppm, 5ppm, 8ppm, 10ppm, 13ppm, 15ppm, 18ppm, and 20ppm.

[0057] In some embodiments, the mass-to-volume ratio of ethylene to organic solvent is (0.5~2):(2~10) kg / L, wherein both ethylene and organic solvent are obtained by column purification. Purification of ethylene and organic solvent can further improve the purity and yield of the reaction. Further limiting the mass-to-volume ratio of ethylene to organic solvent can further improve the reaction yield, reduce byproducts, and improve product purity. Specifically, the mass-to-volume ratio of ethylene to organic solvent is any value from 0.5:2 kg / L, 0.5:5 kg / L, 0.5:8 kg / L, 0.5:10 kg / L, 1:2 kg / L, 1:5 kg / L, 1:10 kg / L, 1:1 kg / L, 2:5 kg / L, 2:8 kg / L, 2:10 kg / L, or any value within a range of both.

[0058] In some embodiments, the mass ratio of ethylene to catalyst is (10000~25000):1. By further limiting the mass ratio of ethylene to catalyst, the polymerization efficiency can be further improved and the uniformity of the molecular weight distribution of the product can be enhanced. Specifically, the mass ratio of ethylene to catalyst is any value from 10000:1, 12000:1, 15000:1, 18000:1, 20000:1, 22000:1, 25000:1, or any value in between.

[0059] In some embodiments, the organic solvent is a mixture of aromatic hydrocarbon solvents and alkane solvents, preferably with a volume ratio of 1:(100~200). The polarity, solubility, evaporation rate, and selectivity for the target substance of the organic solvent are further controlled by the mixture of aromatic hydrocarbon solvents and alkane solvents, thereby meeting the requirements of the reaction system for the organic solvent. Furthermore, limiting the volume ratio of aromatic hydrocarbon solvents to alkane solvents can further improve the overall volatility and solubility of the mixed organic solvent. Specifically, the volume ratio of aromatic hydrocarbon solvents to alkane solvents is any value from 1:100, 1:110, 1:120, 1:130, 1:140, 1:150, 1:160, 1:170, 1:180, 1:190, 1:200, or any value within a range of both.

[0060] In some embodiments, the aromatic hydrocarbon solvent is selected from at least one of benzene, toluene, and xylene, and the alkane solvent is selected from at least one of n-heptane, n-hexane, isooctane, isobutane, n-pentane, isopentane, methylcyclopentane, and methylcyclohexane. By selecting the types of aromatic hydrocarbon solvents and alkane solvents, the solubility and volatility of the organic solvent can be further optimized.

[0061] In some embodiments, the co-catalyst is selected from at least one of triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum chloride, dichloroethylaluminum, methylaluminoxane, and modified methylaluminoxane. The co-catalyst can further and effectively activate the catalyst, generating active centers, thereby improving the catalytic activity and efficiency of the polymerization reaction and regulating the molecular weight and distribution of the polyethylene elastomer.

[0062] In some embodiments, the molar ratio of aluminum in the co-catalyst to nickel in the catalyst is (600~3000):1. By adjusting the molar ratio of aluminum in the co-catalyst to nickel in the catalyst, the catalytic performance of the catalyst can be further optimized. When the molar ratio of aluminum to nickel is too low, nickel is prone to agglomeration, leading to catalyst deactivation. Conversely, when the molar ratio of aluminum to nickel is too high, it may result in reduced activity. Specifically, the molar ratio of aluminum in the co-catalyst to nickel in the catalyst is any value from 600:1, 700:1, 800:1, 900:1, 1000:1, 1200:1, 1500:1, 1800:1, 2000:1, 2200:1, 2500:1, 2800:1, 3000:1, or any value within a range of both.

[0063] In some embodiments, the quenching and deashing treatment includes quenching and deashing. The quenching treatment involves mixing polyethylene adhesive and a quenching agent, followed by heating and stirring. The quenching agent is selected from at least one of ammonium chloride, anhydrous ethanol, acetic acid, hydrochloric acid, sodium hydroxide solution, sodium sulfite solution, methanol, or isopropanol. The quenching temperature is 40-80°C, and the quenching time is 1-6 hours. The deashing treatment includes at least one of washing deashing and adsorption deashing. The washing agent for washing deashing is selected from at least one of anhydrous ethanol, hydrochloric acid, sodium hydroxide solution, oxalic acid, ethyl acetate, sodium bicarbonate solution, and sodium carbonate solution. The washing deashing temperature is 70-100°C. The adsorbent for adsorption deashing is a 3-5A molecular sieve, the adsorption deashing pressure is 1-5 MPa, and the adsorption deashing temperature is 150-200°C. Through quenching and deashing treatment, polyethylene adhesive can efficiently and flexibly remove impurities and ash, improve product purity and performance, reduce environmental pollution, and has good industrial application prospects.

[0064] Specifically, the quenching temperature is any value or a range between any two of 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, and 80℃; the quenching time is any value or a range between any two of 1h, 2h, 3h, 4h, 5h, and 6h; the washing and deashing temperature is any value or a range between any two of 70℃, 80℃, 90℃, and 100℃; the adsorbent for adsorption deashing is any molecular sieve of 3A, 4A, and 5A; the adsorption deashing pressure is any value or a range between any two of 1MPa, 2MPa, 3MPa, 4MPa, and 5MPa; and the adsorption deashing temperature is any value or a range between any two of 150℃, 160℃, 170℃, 180℃, 190℃, and 200℃.

[0065] In some embodiments, the deashed polyethylene adhesive is extruded and granulated using a single-screw extruder to obtain masterbatch-type polyethylene elastomer. The screw speed is 100-120 rpm / min, and the screw temperature is 180-200°C. Extrusion granulation of the polyethylene elastomer can further improve its purity and performance, enhance its processing rheology, and expand its application areas. Specifically, the screw speed is any value or a range between 100 rpm / min, 110 rpm / min, and 120 rpm / min; the screw temperature is any value or a range between 180°C, 190°C, and 200°C.

[0066] In a third typical embodiment of this application, a polyethylene elastomer is provided, which is prepared according to the preparation method provided in the second typical embodiment of this application.

[0067] The catalyst for preparing polyethylene elastomers provided in this application is inexpensive and readily available. This catalyst possesses a specific molecular structure, and its unique steric hindrance and electronic effects result in excellent catalytic activity during the preparation of polyethylene elastomers. The prepared polyethylene elastomer exhibits excellent elasticity and mechanical properties while simultaneously improving branching degree and narrowing molecular weight distribution. This polyethylene elastomer can be widely used in automotive, photovoltaic, medical, and packaging fields, meeting the demand for high-performance polyethylene elastomers in these industries.

[0068] In some embodiments, the branching degree of the polyethylene elastomer is 70-130 branches / 1000°C, and the PDI is 1.84-2.06. With a branching degree of 70-130 branches / 1000°C and a PDI of 1.84-2.06, the polyethylene elastomer possesses excellent elasticity, flexibility, processability, low-temperature performance, and impact resistance, making it suitable for various high-performance applications and demonstrating significant practical application value. Specifically, the degree of branching of the polyethylene elastomer is any value or a range between 70 branches / 1000C, 80 branches / 1000C, 90 branches / 1000C, 100 branches / 1000C, 110 branches / 1000C, 120 branches / 1000C, and 130 branches / 1000C; the PDI is any value or a range between 1.84, 1.86, 1.88, 1.90, 1.92, 1.94, 1.96, 1.98, 2.00, 2.02, 2.04, and 2.06. A branching degree of 70~130 branches / 1000C means that there are 70~130 branches per 1000 main chain carbon atoms.

[0069] This application uses ethylene as the monomer, without employing other comonomers. Under the catalytic action of a catalyst and cocatalyst with a specific structure, an organic solvent is added and mixed before polymerization to prepare a polyethylene elastomer. The polyethylene elastomer is then quenched and deashed, followed by extrusion granulation to obtain masterbatch-type polyethylene elastomer. The specific catalyst used in this application maintains high catalytic activity, thus solving the problem of high-temperature deactivation of polyethylene elastomer. Furthermore, the polyethylene elastomer prepared in this application exhibits high branching degree and narrow molecular weight distribution, as well as excellent elasticity and mechanical properties, enabling its wide application in the automotive, photovoltaic, medical, and packaging fields.

[0070] In the fourth typical embodiment of this application, an application of polyethylene elastomer in the fields of automobiles, photovoltaics, medical, and packaging is provided. The polyethylene elastomer is prepared by the preparation method provided in the second typical embodiment of this application, or by the polyethylene elastomer provided in the third typical embodiment of this application.

[0071] The catalyst for preparing polyethylene elastomers provided in this application is inexpensive and readily available. This catalyst possesses a specific molecular structure, and its unique steric hindrance and electronic effects result in excellent catalytic activity during the preparation of polyethylene elastomers. The prepared polyethylene elastomer exhibits excellent elasticity and mechanical properties while simultaneously improving branching degree and narrowing molecular weight distribution. This polyethylene elastomer can be widely used in automotive, photovoltaic, medical, and packaging fields, meeting the demand for high-performance polyethylene elastomers in these industries.

[0072] The beneficial effects of this application will be further illustrated below with reference to embodiments and comparative examples.

[0073] The structural formula of the compound shown in formula (Ⅰ-1) is: ;

[0074] The structural formula of the compound shown in formula (Ⅰ-2) is: ;

[0075] The structural formula of the compound shown in formula (Ⅱ-1) is: ;

[0076] The structural formula of the compound shown in formula (Ⅱ-2) is: .

[0077] Example 1

[0078] This embodiment provides a method for preparing a polyethylene elastomer, the method comprising the following steps:

[0079] (1) Ethylene, catalyst (Formula I-1) and co-catalyst (triethylaluminum) are added to an organic solvent for dispersion and polymerized at 50°C and 1.35 MPa for 30 min to obtain polyethylene solution. The mass ratio of ethylene to catalyst is 12000:1, the molar ratio of aluminum to nickel in co-catalyst is 700:1, the mass-volume ratio of ethylene to organic solvent is 1:33 kg / L, and the organic solvent is a compound solvent of n-hexane and toluene with a volume ratio of n-hexane to toluene of 1:150.

[0080] (2) The polyethylene liquid was quenched at 60°C for 2 hours, and then adsorbed and deashed using 4A molecular sieve at 170°C and 3MPa. Then it was extruded and granulated to obtain masterbatch type polyethylene elastomer. The screw speed of the extrusion granulation was 110rpm / min, and the screw temperature was controlled at 190°C.

[0081] Example 2

[0082] The difference between this embodiment and Embodiment 1 is that the polymerization temperature is adjusted to 85°C and the polymerization pressure is 1.25 MPa.

[0083] Example 3

[0084] The difference between this embodiment and Example 1 is that catalyst (Ⅰ-1) is replaced with catalyst (Ⅰ-2), the polymerization temperature is 70°C, the polymerization pressure is 1.0 MPa, and the molar ratio of aluminum in the co-catalyst to nickel in the catalyst is 750:1.

[0085] Example 4

[0086] The difference between this embodiment and Example 1 is that catalyst (Ⅰ-1) is replaced with (Ⅰ-2) and the polymerization temperature is adjusted to 40°C.

[0087] Example 5

[0088] The difference between this embodiment and Embodiment 1 is that the pressure of the polymerization process is adjusted to 1.2 MPa.

[0089] Example 6

[0090] The difference between this embodiment and Embodiment 1 is that the polymerization temperature is adjusted to 30°C and the polymerization pressure is adjusted to 6 MPa.

[0091] Example 7

[0092] The difference between this embodiment and Example 1 is that catalyst (Ⅰ-1) is replaced with (Ⅱ-1).

[0093] Example 8

[0094] The difference between this embodiment and Example 1 is that catalyst (Ⅰ-1) is replaced with (Ⅱ-2).

[0095] Example 9

[0096] The difference between this embodiment and Example 1 is that the mass ratio of ethylene to catalyst is adjusted to 10000:1.

[0097] Example 10

[0098] The difference between this embodiment and Example 1 is that the mass ratio of ethylene to catalyst is adjusted to 25000:1.

[0099] Example 11

[0100] The difference between this embodiment and Example 1 is that the molar ratio of aluminum in the co-catalyst to nickel in the catalyst is adjusted to 600:1.

[0101] Example 12

[0102] The difference between this embodiment and Example 1 is that the molar ratio of aluminum in the co-catalyst to nickel in the catalyst is adjusted to 3000:1.

[0103] Example 13

[0104] The difference between this embodiment and Example 1 is that the mass-to-volume ratio of ethylene and organic solvent is adjusted to 1:1 kg / L.

[0105] Example 14

[0106] The difference between this embodiment and Example 1 is that the mass-to-volume ratio of ethylene and organic solvent is adjusted to 0.5:10 kg / L.

[0107] Example 15

[0108] The difference between this embodiment and Example 1 is that the organic solvent is hexane and toluene in a volume ratio of 1:100.

[0109] Example 16

[0110] The difference between this embodiment and Example 1 is that the organic solvent is hexane and toluene in a volume ratio of 1:200.

[0111] Example 17

[0112] The difference between this embodiment and Embodiment 1 is that the polymerization pressure is adjusted to 0.5 MPa and the polymerization temperature is 90°C.

[0113] Example 18

[0114] The difference between this embodiment and Embodiment 1 is that the polymerization pressure is adjusted to 8 MPa and the polymerization temperature is 20°C.

[0115] Example 19

[0116] The difference between this embodiment and Example 1 is that the mass ratio of ethylene to catalyst is adjusted to 8000:1.

[0117] Example 20

[0118] The difference between this embodiment and Example 1 is that the mass ratio of ethylene to catalyst is adjusted to 27000:1.

[0119] Example 21

[0120] The difference between this embodiment and Example 1 is that the molar ratio of aluminum in the co-catalyst to nickel in the catalyst is adjusted to 500:1.

[0121] Example 22

[0122] The difference between this embodiment and Example 1 is that the molar ratio of aluminum in the co-catalyst to nickel in the catalyst is adjusted to 4000:1.

[0123] Example 23

[0124] The difference between this embodiment and Example 1 is that the mass-to-volume ratio of ethylene to organic solvent is 2:1 kg / L.

[0125] Example 24

[0126] The difference between this embodiment and Example 1 is that the mass-to-volume ratio of ethylene to organic solvent is 1:25 kg / L.

[0127] Example 25

[0128] The difference between this embodiment and Example 1 is that the organic solvent is hexane and toluene in a volume ratio of 1:50.

[0129] Example 26

[0130] The difference between this embodiment and Example 1 is that the organic solvent is hexane and toluene in a volume ratio of 1:230.

[0131] Example 27

[0132] The difference between this embodiment and Example 1 is that no co-catalyst (triethylaluminum) is added to the organic solvent; only the catalyst and ethylene are added for polymerization.

[0133] Comparative Example 1

[0134] The difference between this comparative example and Example 1 is that the catalyst (Ⅰ-1) was replaced with N,N-bis(salicylene)ethylenediaminonickel (Ⅱ) (Merck Chemical Technology Co., Ltd., CAS: 14167-20-5).

[0135] Comparative Example 2

[0136] The difference between this comparative example and Example 1 is that the catalyst (Ⅰ-1) was replaced with N,N-bis(salicylene)-o-phenylenediamine nickel (Ⅱ) (Shanghai Haohong Biomedical Technology Co., Ltd. (Leyan Reagent), CAS:14406-71-4).

[0137] Experimental Example 1

[0138] The polyethylene elastomers prepared in the above embodiments and comparative examples were subjected to performance tests, wherein...

[0139] Melting point test: Refer to national standard GB / T 19466.3-2022;

[0140] Catalytic activity ratio: Calculated using conventional methods for calculating the coordination catalytic activity of polyolefins, i.e.

[0141]

[0142] Where, m polymer For the mass of the generated polymer, m catalyst Here, t represents the catalyst mass, and t represents the reaction time.

[0143] Branching degree test: Refer to ASTM E386-19;

[0144] PDI test: Refer to national standard GB / T 36214-2018;

[0145] Fracture stress and fracture strain testing: Refer to national standard GB / T 1040.2-2018;

[0146] Density test: Refer to national standard GB / T 1033.1-2008;

[0147] Elastic modulus test: Refer to national standard GB / T 1040.2-2018;

[0148] Elastic recovery rate: calculated with reference to national standard GB / T 17031.1-2020.

[0149] The data obtained from the above tests and calculations are shown in Table 1.

[0150] Table 1

[0151]

[0152]

[0153] The branching degree of the polyethylene elastomers prepared in the above examples and comparative examples was analyzed, and the branching rate of each group was measured by high-temperature carbon NMR spectroscopy, as shown in Table 2.

[0154] Table 2

[0155]

[0156] As can be seen from the comparison between Examples 1-25 and Comparative Examples 1-2, the polyethylene elastomer provided in this application exhibits higher catalytic activity, higher branching degree, and better mechanical properties. Furthermore, the branching rate of each group in the polyethylene elastomer prepared in Examples 1-25 is higher. It can be seen that the specific molecular structure of the catalyst provided in this application for preparing polyethylene elastomers, combined with its unique steric hindrance and electronic effects, enables the catalyst to exhibit excellent catalytic activity during the preparation process. Therefore, the prepared polyethylene elastomer possesses excellent elasticity and mechanical properties while maintaining a narrow molecular weight with increased branching degree. In contrast, the more conventional catalysts used in Comparative Examples 1-2 resulted in poorer catalytic performance, elasticity, and mechanical properties.

[0157] As can be seen from the comparison between Examples 1-16 and Examples 17-18, the appropriate polymerization pressure and temperature in Examples 1-16 can further regulate the polyethylene elastomer preparation process, significantly improve polymerization efficiency, and reduce side reactions and energy consumption.

[0158] As can be seen from the comparison between Examples 1-16 and Examples 19-20, the appropriate mass ratio of ethylene to catalyst in Examples 1-16 can further improve the uniformity of the molecular weight distribution of the product.

[0159] As can be seen from the comparison between Examples 1-16 and Examples 21-22, the appropriate molar ratio of aluminum in the co-catalyst and nickel in the catalyst in Examples 1-16 can further optimize the catalytic performance of the catalyst. When the molar ratio of aluminum to nickel is too low, nickel is prone to agglomeration, which leads to catalyst deactivation. When the molar ratio of aluminum to nickel is too high, it may lead to a decrease in activity.

[0160] As can be seen from the comparison between Examples 1-16 and Examples 23-24, the appropriate mass-volume ratio of ethylene to organic solvent in the preparation of polyethylene elastomers in Examples 1-16 can further improve the purity and yield of the reaction and reduce by-products.

[0161] As can be seen from the comparison between Examples 1-16 and Examples 25-26, the polyethylene elastomers prepared in Examples 1-16 have better catalytic activity ratio, elasticity and mechanical properties, indicating that the appropriate volume ratio of aromatic hydrocarbon solvents and alkane solvents in organic solvents can further improve the polarity and solubility of organic solvents.

[0162] Comparing Examples 1-16 and Example 27, it can be seen that the polyethylene elastomers prepared in Examples 1-16 have better catalytic activity ratio, elasticity, and mechanical properties. This indicates that the addition of the co-catalyst can further effectively activate the catalyst, generate activation centers, and thus improve the catalytic activity and efficiency of the polymerization reaction, and regulate the molecular weight and distribution of the polyethylene elastomer.

[0163] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0164] The catalyst provided in this application for preparing polyethylene elastomers is inexpensive and readily available. This catalyst possesses a specific molecular structure, and its unique steric hindrance and electronic effects during the preparation process result in excellent catalytic activity. The prepared polyethylene elastomer exhibits superior elasticity and mechanical properties while simultaneously improving branching degree and narrowing molecular weight distribution. This polyethylene elastomer can be widely used in automotive, photovoltaic, medical, and packaging fields, meeting the demand for high-performance polyethylene elastomers in these industries.

[0165] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A catalyst for preparing polyethylene elastomers, characterized in that, The catalyst has a structure as shown in Formula I or Formula II: Formula I Formula II Among them, R 1 ~R 10 Each is independently selected from H, substituted or unsubstituted C1-C4 alkyl groups; a, c, d, f are each independently integers between 1 and 4; b, e are each independently integers between 1 and 2; g, j are each independently integers between 1 and 3; h and i are each independently integers between 1 and 6; X is selected from halogens.

2. The catalyst according to claim 1, characterized in that, R 1 ~R 10 Each is independently selected from H, substituted or unsubstituted C1 to C4 alkyl groups; a, c, d, f are each independently 1, 2, 3 or 4; b, e are each independently 1 or 2; g, j are each independently 1, 2 or 3; h, i are each independently 1, 2, 3, 4, 5 or 6; X is selected from Cl and Br.

3. The catalyst according to claim 1, characterized in that, The catalyst has the structures shown in formulas (I-1), (I-2), (II-1), and (II-2): Equation (Ⅰ-1) Equation (Ⅰ-2) Equation (Ⅱ-1) Equation (Ⅱ-2).

4. A method for preparing a polyethylene elastomer, characterized in that, The preparation method includes: dispersing the catalyst, ethylene and co-catalyst according to any one of claims 1 to 3 in an organic solvent for polymerization treatment to obtain the polyethylene elastomer.

5. The method for preparing polyethylene elastomer according to claim 4, characterized in that, The preparation method includes first dispersing the catalyst, ethylene, and the co-catalyst in the organic solvent to carry out the polymerization treatment to obtain a polyethylene solution; then quenching and deashing the polyethylene solution, and finally extruding and granulating it to obtain a masterbatch type polyethylene elastomer.

6. The method for preparing polyethylene elastomer according to claim 4, characterized in that, The polymerization treatment temperature is 30~85℃, the polymerization treatment pressure is 1~6MPa, the polymerization treatment time is 20~50min, and the water content of the polymerization treatment system is ≤20ppm.

7. The method for preparing polyethylene elastomer according to claim 4, characterized in that, The mass-to-volume ratio of ethylene to the organic solvent is (0.5~2):(2~10) kg / L; And / or, the mass ratio of ethylene to the catalyst is (10000~25000):1; And / or, the organic solvent is a mixture of aromatic hydrocarbon solvents and alkane solvents; Preferably, the volume ratio of the aromatic hydrocarbon solvent to the alkane solvent is 1:(100~200). Preferably, the aromatic hydrocarbon solvent is selected from at least one of benzene, toluene, and xylene; Preferably, the alkane solvent is selected from at least one of n-heptane, n-hexane, isooctane, isobutane, n-pentane, isopentane, methylcyclopentane, and methylcyclohexane.

8. The method for preparing polyethylene elastomer according to claim 4, characterized in that, The co-catalyst is selected from at least one of triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum chloride, dichloroethylaluminum, methylaluminoxane, and modified methylaluminoxane; Preferably, the molar ratio of aluminum in the co-catalyst to nickel in the catalyst is (600~3000):

1.

9. A polyethylene elastomer, characterized in that, The polyethylene elastomer is prepared by the preparation method according to any one of claims 4 to 8; And / or, the degree of branching of the polyethylene elastomer is 70~130 branches / 1000C, and the PDI is 1.84~2.

06.

10. An application of a polyethylene elastomer in the automotive, photovoltaic, medical, and packaging fields, characterized in that... The polyethylene elastomer is a polyethylene elastomer prepared by the preparation method of any one of claims 4 to 8 or a polyethylene elastomer provided in claim 9.

Images