Catalyst system, ethylene / acrylic acid (ester) copolymer and preparation method thereof

Abstract

The invention belongs to the field of olefin polymerization, and relates to a catalyst system, an ethylene / acrylic acid (ester) copolymer and a preparation method thereof. The catalyst system consists of the following components: a component a, a main catalyst which is selected from at least one of compounds shown as a formula (I), and a component b which is selected from at least one of compounds shown as a formula (II) and compounds shown as a formula (III). According to the catalyst system disclosed by the invention, the late transition metal catalyst and the phenol compound are cooperatively used, so that the reaction activity of coordination polymerization of ethylene and the polar monomer is remarkably improved under the condition that a cocatalyst is not needed, and the reaction activity is remarkably improved when the catalyst system is applied to preparation of the ethylene / acrylic acid (ester) copolymer; and the copolymer with high comonomer content can be prepared under relatively low pressure.

Description

Technical Field

[0001] The invention belongs to the field of olefin polymerization, and in particular, relates to a catalyst system for ethylene / polar monomer copolymerization, a method for preparing an ethylene / acrylic acid (ester) copolymer, and an ethylene / acrylic acid (ester) copolymer prepared by the method. Background Art

[0002] Polyolefins are cheap, have excellent performance, and are highly mature in industrialization, accounting for about half of the world's polymer materials. Polyolefin materials are cost-effective, and their molecular structure contains only the simplest carbon-hydrogen units, lacking polar groups, which is not conducive to applications such as printing and dyeing, bonding, and blending. Therefore, it is necessary to introduce polar groups to achieve polyolefin functionalization.

[0003] Introducing polar groups into polymer molecular chains is an important method for modifying polymers. The introduction of polar groups can effectively improve the hardness, viscoelasticity, interface properties, surface properties, adaptability to solvents, blending properties with other polymers, rheological properties, etc. of polymers, and has a great influence on various properties of polymers. Therefore, combining the inherent material properties of polyolefins with the new properties given by the polar groups in the functionalized monomers can greatly expand the application range of polyolefins. This copolymer is a functionalized polyolefin, which can make polymers highly value-added and broaden their commercial uses. Summary of the invention

[0004] The object of the present invention is to provide a catalyst system for ethylene / polar monomer copolymerization, and based on this, further provide an ethylene / acrylic acid (ester) copolymer and a preparation method thereof.

[0005] The first aspect of the present invention provides a catalyst system for ethylene / polar monomer copolymerization, the catalyst system consisting of the following components:

[0006] Component a, the main catalyst, is selected from at least one of the compounds represented by formula (I),

[0007]

[0008] In formula (I), R 1 , R 2 , R 3 are the same or different and are each independently a hydrogen atom, a substituted or unsubstituted C 1 -C 20 Hydrocarbon, substituted or unsubstituted C 1 -C 20 Alkoxy or substituted or unsubstituted C 6 -C 20 Aryloxy groups are linear, branched or cyclic and are optionally substituted by halogen atoms, C 1 -C 10Alkyl, C 1 -C 10 Alkoxy, C 6 -C 10 Aryl or C 6 -C 10 is further substituted, and L is a ligand;

[0009] Component b is selected from at least one of the compounds represented by formula (II) and the compounds represented by formula (III):

[0010]

[0011] In formula (II), R 4 is selected from a hydrogen atom, a substituted or unsubstituted C 1 -C 20 hydrocarbyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group or a substituted or unsubstituted C 6 -C 20 aryloxy group, and these groups are linear, branched or cyclic and are optionally further substituted by a halogen atom, C 1 -C 10 alkyl group, C 1 -C 10 alkoxy group, C 1 -C 6 carbonyl group, C 6 -C 10 aryl group or C 6 -C 10 aryloxy group;

[0012] In formula (III), R 5 is selected from a hydrogen atom, a substituted or unsubstituted C 1 -C 20 hydrocarbyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group or a substituted or unsubstituted C 6 -C 20 aryloxy group, and these groups are linear, branched or cyclic and are optionally further substituted by a halogen atom, C 1 -C 10 alkyl group, C 1 -C 10 alkoxy group, C 1 -C 6 carbonyl group, C 6 -C 10 aryl group or C 6 -C 10 aryloxy group.

[0013] The second aspect of the present invention provides the application of the above catalyst system in the copolymerization reaction of ethylene / polar monomer.

[0014] The third aspect of the present invention provides a method for preparing an ethylene / acrylic acid (ester) copolymer, the preparation method comprising: in the presence of a catalyst system, subjecting ethylene and an acrylic acid (ester) monomer to a polymerization reaction in an inert solvent to obtain an ethylene / acrylic acid (ester) copolymer;

[0015] The catalyst system is the above-mentioned catalyst system;

[0016] The acrylic acid (ester) monomer is at least one of the compounds represented by formula (A),

[0017]

[0018] In formula (A), R a is a hydrogen atom, a linear or branched C 1 -C 4 alkyl group, and R b is a hydrogen atom, a linear or branched C 1 -C 10 alkyl group.

[0019] The fourth aspect of the present invention provides an ethylene / acrylic acid (ester) copolymer prepared by the above-mentioned preparation method.

[0020] The catalyst system of the present invention, by using a late transition metal catalyst and a phenol compound in combination, significantly improves the reaction activity of the coordination polymerization of ethylene and polar monomers without the need for a cocatalyst. When it is applied to the preparation of an ethylene / acrylic acid (ester) copolymer, the reaction activity is significantly improved, and a copolymer with a high comonomer content can be prepared at a lower pressure. Moreover, the prepared ethylene / acrylic acid (ester) copolymer has a high comonomer insertion rate, which will significantly improve the polarity of the polyethylene material, improve the interfacial properties, adhesiveness, and compatibility with other materials of the polyethylene material, and thus enhance the comprehensive properties of polyolefins.

[0021] Other features and advantages of the present invention will be described in detail in the following specific embodiments section. Specific Embodiments

[0022] The following provides a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention and are not intended to limit the present invention.

[0023] The present invention provides a catalyst system for the copolymerization of ethylene and polar monomers, and the catalyst system is composed of the following components:

[0024] Component a, the main catalyst, is selected from at least one of the compounds represented by formula (I),

[0025]

[0026] In formula (I), R 1 , R 2 , R 3 are the same or different and each independently is a hydrogen atom, a substituted or unsubstituted C 1 -C 20 hydrocarbyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group or a substituted or unsubstituted C 6 -C 20 aryloxy group, and these groups are linear, branched or cyclic and are optionally further substituted by a halogen atom, a C 1 -C 10 alkyl group, a C 1 -C 10 alkoxy group, a C 6 -C 10 aryl group or a C 6 -C 10 aryloxy group, and L is a ligand; preferably, in formula (I), R 1 , R 2 , R 3 are the same or different and each independently is a hydrogen atom, a substituted or unsubstituted C 1 -C 10 hydrocarbyl group, a substituted or unsubstituted C 1 -C 10 alkoxy group or a substituted or unsubstituted C 6 -C 10 aryloxy group, and these groups are linear, branched or cyclic and are optionally further substituted by a halogen atom, a C 1 -C 6 alkyl group, a C 1 -C 6 alkoxy group, a C 6 -C 8 aryl group or a C 6 -C 8 aryloxy group, and L is Me 2 SO; more preferably, R 1 , R 2 , R 3 are the same or different and each independently is a hydrogen atom, a substituted or unsubstituted C 1 -C 6 alkyl group, a substituted or unsubstituted C 1 -C 6 alkoxy group or a substituted or unsubstituted C 6 -C 8 aryloxy group, and these groups are linear, branched or cyclic and are optionally further substituted by a halogen atom, a C 1 -C 6 alkyl group, a C1 -C 6 alkoxy, C 6 -C 8 aryl or C 6 -C 8 aryloxy is further substituted;

[0027] Component b is selected from at least one of the compounds represented by formula (II) and the compounds represented by formula (III):

[0028]

[0029] In formula (II), R 4 is selected from a hydrogen atom, a substituted or unsubstituted C 1 -C 20 hydrocarbyl, a substituted or unsubstituted C 1 -C 20 alkoxy or a substituted or unsubstituted C 6 -C 20 aryloxy, and these groups are linear, branched or cyclic and are optionally substituted by a halogen atom, C 1 -C 10 alkyl, C 1 -C 10 alkoxy, C 1 -C 6 carbonyl, C 6 -C 10 aryl or C 6 -C 10 aryloxy is further substituted; Preferably, in formula (II), R 4 is selected from a hydrogen atom, a substituted or unsubstituted C 1 -C 10 alkyl, a substituted or unsubstituted C 8 -C 16 conjugated cycloalkyl, a substituted or unsubstituted C 1 -C 10 alkoxy or a substituted or unsubstituted C 6 -C 10 aryloxy, and these groups are linear, branched or cyclic and are optionally substituted by a halogen atom, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, C 1 -C 3 carbonyl, C 6 -C 8 aryl or C 6 -C 8 aryloxy is further substituted;

[0030] In formula (III), R 5Selected from a hydrogen atom, a substituted or unsubstituted C 1 -C 20 hydrocarbyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group, or a substituted or unsubstituted C 6 -C 20 aryloxy group, these groups being linear, branched or cyclic and optionally further substituted by a halogen atom, a C 1 -C 10 alkyl group, a C 1 -C 10 alkoxy group, a C 1 -C 6 carbonyl group, a C 6 -C 10 aryl group or a C 6 -C 10 aryloxy group; preferably, in formula (III), R 5 is selected from a hydrogen atom, a substituted or unsubstituted C 1 -C 10 alkyl group, a substituted or unsubstituted C 8 -C 16 conjugated cycloalkenyl group, a substituted or unsubstituted C 1 -C 10 alkoxy group, or a substituted or unsubstituted C 6 -C 10 aryloxy group, these groups being linear, branched or cyclic and optionally further substituted by a halogen atom, a C 1 -C 6 alkyl group, a C 1 -C 6 alkoxy group, a C 1 -C 3 carbonyl group, a C 6 -C 8 aryl group or a C 6 -C 8 aryloxy group.

[0031] According to some specific embodiments of the present invention, the component a is at least one of palladium 2-(bis(2-methoxyphenyl)phosphino)benzenesulfonate, palladium 2-(bis(2-phenoxyphenyl)phosphino)benzenesulfonate, and palladium 2-(bis(2-methoxyphenyl)phosphino)-4-methylbenzenesulfonate.

[0032] According to some specific embodiments of the present invention, the component b is at least one of 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol, and 2,6-di-tert-butyl-α-(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadienylidene)-p-tolyloxy radical.

[0033] According to the present invention, preferably, the molar ratio of the component a to the component b in terms of Pd atoms is 1:1 to 1:200, preferably 1:3 to 1:100, more preferably 1:4 to 1:50, and further preferably 1:5 to 1:30.

[0034] The catalyst system of the present invention is only formed by the component a and the component b, without the need for conventional cocatalysts (such as alkylaluminum, alkylaluminoxane, organic boron compounds, etc.) in the field of olefin polymerization. This catalyst system is applicable to the copolymerization reaction of ethylene / polar monomers, can improve the reaction activity, increase the content of comonomers, and significantly improve the insertion rate of comonomers.

[0035] In the present invention, the concept of "polar monomer" is well-known to those skilled in the art and refers to an olefin monomer containing one or more polar groups. According to a specific embodiment of the present invention, the polar monomer is an acrylic acid (ester) monomer.

[0036] The present invention provides a method for preparing an ethylene / acrylic acid (ester) copolymer, and the preparation method includes: in the presence of a catalyst system, subjecting ethylene and an acrylic acid (ester) monomer to a polymerization reaction in an inert solvent to obtain an ethylene / acrylic acid (ester) copolymer;

[0037] The catalyst system is the above-mentioned catalyst system;

[0038] The acrylic acid (ester) monomer is at least one of the compounds represented by the formula (A),

[0039]

[0040] In the formula (A), R a is a hydrogen atom, a straight-chain or branched C 1 -C 4 alkyl group, and R b is a hydrogen atom, a straight-chain or branched C 1 -C 10 alkyl group.

[0041] The method of the present invention is applicable to acrylic acid (ester) monomers, and the general formula is as shown in the formula (A). Preferably, R a is a hydrogen atom or a methyl group, and R b is a hydrogen atom, a straight-chain or branched C 1 -C 8 alkyl group; the C 1 -C 8 alkyl group includes but is not limited to methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl.

[0042] Specifically and preferably, the (meth)acrylic acid monomer is at least one of acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate and 2-ethylhexyl methacrylate.

[0043] The inert solvent used in the preparation method of the present invention can be various inert solvents commonly used in the field of olefin polymerization, including aliphatic hydrocarbon solvents and / or aromatic hydrocarbon solvents; preferably, the inert solvent is a straight-chain, branched-chain or cyclic C 6 -C 12 alkane and / or C 6 -C 10 monocyclic aromatic hydrocarbon; wherein the C 6 -C 12 alkane is preferably at least one of n-hexane, iso-hexane, n-heptane, iso-heptane, n-octane, iso-octane and cyclohexane; the C 6 -C 10 monocyclic aromatic hydrocarbon is preferably toluene and / or xylene; more preferably, the inert solvent is at least one of n-hexane, iso-hexane, cyclohexane and toluene, and most preferably toluene.

[0044] According to a preferred embodiment of the present invention, the (meth)acrylic acid monomer is premixed with the component b in the catalyst system to obtain a premix, and then mixed with other components of the polymerization reaction system, which can further improve the reaction activity. Specifically, the premixing time is preferably 1 to 30 minutes, more preferably 2 to 15 minutes, and further preferably 3 to 10 minutes.

[0045] The method of the present invention can increase the insertion rate of the comonomer in the main chain. Therefore, without a too high comonomer addition amount, the copolymer can have a high comonomer content. Specifically, in the polymerization reaction system, the concentration of the (meth)acrylic acid monomer can be 5 mol / L or less, preferably 2 mol / L or less, and more preferably 1 mol / L or less.

[0046] According to the present invention, preferably, the molar ratio of the (meth)acrylic acid monomer to the component b in the catalyst system is 50:1 to 800:1, preferably 100:1 to 350:1, and more preferably 150:1 to 300:1.

[0047] The polymerization of the present invention can be carried out in a continuous or semi-continuous operation, or in a batch operation.

[0048] The polymerization of the present invention can adopt milder process conditions. Specifically, the temperature of the polymerization reaction can be 20 to 150 °C, preferably 40 to 120 °C, more preferably 60 to 100 °C; the pressure of the polymerization reaction can be below 10 MPa, preferably 0.01 to 5 MPa, more preferably 0.1 to 2 MPa.

[0049] For ethylene / acrylic acid (ester) copolymers, to obtain a higher comonomer content, high-pressure free radical reactions are usually required. The present invention adopts the coordination polymerization as described above, and an ethylene / acrylic acid (ester) copolymer with a high comonomer content can be obtained under lower pressure.

[0050] The preparation method of the present invention further includes separating the obtained copolymer from the solvent and unreacted monomers, and various separation methods commonly used in the field of olefin polymerization can be adopted, such as evaporation. The preparation method also includes drying the copolymer after separating and removing the solvent and unreacted monomers.

[0051] The present invention also provides an ethylene / acrylic acid (ester) copolymer prepared by the above preparation method.

[0052] The copolymer may contain 75 to 99 mol% of structural units derived from ethylene and 1 to 25 mol% of structural units derived from acrylic acid (ester) monomers; the proportion of acrylic acid (ester) inserted into the main chain of the copolymer can be above 70 mol%, preferably above 80 mol%, further preferably above 85 mol%, and more preferably above 90 mol%.

[0053] According to the present invention, the proportion of acrylic acid (ester) inserted into the main chain of the copolymer (comonomer insertion rate) refers to the ratio of the molar amount of the structural units derived from acrylic acid (ester) on the polymer main chain to the total molar amount of the structural units derived from acrylic acid (ester) in the copolymer.

[0054] The present invention will be further described below with reference to examples, but the scope of the present invention is not limited to these examples.

[0055] The comonomer content in the product is determined by the following method: Nuclear magnetic resonance hydrogen spectrum measurement is carried out at room temperature using deuterated chloroform as the solvent. The chemical shifts of 3.59 ppm and 3.66 ppm are taken as the signals of the MA units on the polymer chain and the chain-end MA units respectively. The MA content in the product and the proportion of MA inserted into the main chain of the copolymer are calculated by comparing the peak areas.

[0056] The number-average molecular weight was determined by the following method: high-temperature GPC was used for determination, and a PL-GPC 220 gel permeation chromatograph from Polymer Laboratory was adopted. The sample was dissolved in 1,2,4-trichlorobenzene with a concentration of 1.0 mg / ml. The test temperature was 150 °C, and the solution flow rate was 1.0 ml / min. The molecular weight of polystyrene was used as an internal reference to establish a standard curve, and the molecular weight of the sample was calculated based on the elution time.

[0057] The method for the determination and calculation of the proportion of acrylic acid (ester) inserted into the main chain of the copolymer was as follows: nuclear magnetic resonance hydrogen spectrum was measured using deuterated chloroform as a solvent at room temperature. The chemical shifts of 3.59 ppm and 1.25 ppm were taken as the signals of the MA unit and polyethylene unit on the polymer chain respectively, and the proportion of acrylic acid (ester) inserted into the main chain of the copolymer was calculated by comparing the peak areas.

[0058] The catalyst PSPd-1 used was prepared by the following method:

[0059]

[0060] An 2 Preparation of P(OMe)

[0061] An 2 PNEt 2 (103 g, 325 mmol) in methanol (200 mL) was heated to 65 °C and stirred for 4 hours. After cooling to room temperature, the solution was concentrated under vacuum to obtain a white solid An 2 P(OMe) (88.5 g, yield 99%). 1 H NMR(CD 2 Cl 2 ): δ = 3.68 (d, 3H, POCH 3 ), 3.82 (s, 6H, 2OCH3), 6.9 - 7.4 (m, 8H, arom); 31 PNMR(CD 2 Cl 2 ): δ = 101.7 ppm.

[0062] Preparation of phosphine sulfonic acid ligand 1a

[0063] At 0 °C, a solution of hexyl lithium (25 ml, 62 mmol, 2.5 M hexane solution) was added dropwise to a solution of benzenesulfonic acid (5.2 g, 32.9 mmol) in 60 mL of tetrahydrofuran. After the temperature was raised to room temperature and stirred for 20 hours, a solution of bis[2-((oxo)diphenylphosphino)phenyl] ether (9.1 g, 32.9 mmol) in 20 mL of tetrahydrofuran was added dropwise to the solution and stirring was continued for 16 hours. Then ammonium chloride (3.4 g, 62 mmol) was added thereto, and the mixture was concentrated under reduced pressure. 100 mL of water was added to the crude product. This mixture was washed twice with 80 mL of methyl tert-butyl ether and acidified to pH = 2 with concentrated hydrochloric acid. The aqueous phase was extracted twice with 120 mL of dichloromethane, the combined organic phases were dried over anhydrous magnesium sulfate, filtered, and the filtrate was cooled to -35 °C until white crystals precipitated. The solid was collected and dried to obtain the phosphonic acid ligand 1a (3.72 g, yield 28%). 1 H NMR(C 2 D 2 Cl 4 ,400 MHz, -25 °C) δ = 9.25 (d, 1 JPH = 607 Hz, PH), 6.7 - 8.2 (m, 12H, arom), 3.79 (s, 6H, 2OCH 3 ).

[0064] PdCl 2 (TMEDA) Preparation

[0065] A solution of palladium dichloride (1.76 g, 10 mmol) in 50 mL of methanol was heated to reflux and dissolved. After cooling to 20 °C, 2 mL of tetramethylethylenediamine (TMEDA) was added thereto, and a yellow solid precipitated. The yellow solid was collected, washed with diethyl ether, and dried under vacuum to obtain the product (2.5 g, yield 90%).

[0066] PdMe 2 (TMEDA) Preparation

[0067] PdCl 2 (TMEDA) (2.37 g, 8 mmol) was dispersed in 30 mL of diethyl ether and cooled to -30 °C, and a solution of methyllithium in diethyl ether (12 mL, 1.44 M) was added dropwise thereto. The temperature was gradually raised to 0 °C during stirring and maintained for 1 hour, and a grayish-white suspension gradually formed. 10 mL of cold water was slowly added to this mixture and stirred until the diethyl ether phase became clear and the aqueous phase became black. The organic phase was separated, dried over anhydrous sodium sulfate, and concentrated under vacuum to obtain colorless crystals of PdMe 2 (TMEDA) (1.2 g, yield 60%). 1 H NMR(200 MHz, CD 3 COCD 3) 303 K, 0.34 (s, 3H, PdMe), 2.40 (s, 6H, NMe 2 ), 2.57 (s, 2H, CH 2 ); 183 K, -0.36 (s, PdMe), 2.20 (dd, J(H,H) = 10 Hz, CHH-CHH), 2.33 (s, NMeAfe), 2.34 (s, NMeAfe), 2.96 (dd, J(H,H) = 10 Hz, CHH-CHH).

[0068] Preparation of 1a-PdTMEDA

[0069] At room temperature, phosphonic acid ligand 1a (1 g, 2.49 mmol) and PdMe 2 (TMEDA) (0.63 g, 2.49 mmol) were dissolved in dioxane. With the generation of bubbles, the product rapidly precipitated from the solution. After the mixture was stirred for an additional 60 minutes, it was filtered. The solid phase was washed with ether and dried under reduced pressure to obtain 1a-PdTMEDA (1.4 g, yield 98%). 1 1H NMR (400 MHz, DMSO-d6) δ = 7.7 - 6.8 (m, 20H), 6.35 (m, 4H), 3.49 (s, 12H, OCH3), 2.30 (s, 4H, NCH2), 2.13 (s, 12H, NCH3), 0.10 (6H, Pd-CH3).

[0070] Preparation of PSPd-1

[0071] At room temperature, 1a-PdTMEDA (115 mg, 0.20 mmol) was suspended in 50 mL of dimethyl sulfoxide and stirred, then the solvent was removed by vacuum concentration. This process was repeated until the solid was completely dissolved in DMSO. The solution was concentrated under reduced pressure, and ether was added to the remaining solid. The solid was filtered (90.1 mg, yield 76%). 1 1H NMR (600 MHz, CD2Cl2, 25 °C): δ 8.06 (ddd, 3JHH = 8.0 Hz, 4JPH = 4.9, 4JHH = 1.0, 1H, 6-H), 7.55 (vt, J = 7.6, 2H, 10-H), 7.48 (vt, J = 7.5, 2H, 12-H), 7.45 (br, 1H, 5-H), 7.31 (vt, J = 7.6, 1H, 4-H), 7.25 (ddd, 3JHH = 11.3.

[0072] Other catalysts were prepared according to the above preparation method by changing the structure of the phosphonic acid ligand.

[0073] Examples 1 - 4

[0074] This example is used to illustrate the ethylene / acrylic acid (ester) copolymer of the present invention and its preparation method. The preparation is carried out in a 1.8 L reactor equipped with mechanical stirring and a jacket, connected to an ethylene pipeline, and the reaction temperature is controlled by the oil bath temperature in the jacket.

[0075] The preparation method is as follows:

[0076] (1) According to the amounts in Table 1, methyl acrylate (MA) and 2,6-di-tert-butyl-4-methylphenol (Component b) are premixed for 5 minutes to obtain a premix.

[0077] (2) 1000 mL of toluene, 140 μmol of palladium 2-(bis(2-methoxyphenyl)phosphino)-4-methylbenzenesulfonate (counted as Pd atoms), and the premix are added into the reactor. The temperature in the reactor is set to 80 °C, ethylene is continuously introduced into the reactor, and the reactor pressure is set to 10 bar. After half an hour, the addition of ethylene is stopped, and acidified ethanol is injected to terminate the reaction. After depressurization, the reaction solution is poured into a flask, the solvent and unreacted monomers are evaporated, and it is placed in a vacuum oven and dried at 70 °C for 24 hours. The polymerization results and characterization data are shown in Table 1, and the activity without adding Component b is used as the comparative data.

[0078] Table 1

[0079]

[0080] Examples 5 - 8

[0081] This example is used to illustrate the ethylene / acrylic acid (ester) copolymer of the present invention and its preparation method. The preparation is carried out in a 1.8 L reactor equipped with mechanical stirring and a jacket, connected to an ethylene pipeline, and the reaction temperature is controlled by the oil bath temperature in the jacket.

[0082] The preparation method is as follows:

[0083] (1) According to the amounts in Table 2, n-butyl acrylate (BA) and 2,6-di-tert-butyl-4-methylphenol (Component b) are premixed for 5 minutes to obtain a premix.

[0084] (2) 1000 mL of toluene, 140 μmol of palladium 2-(bis(2-methoxyphenyl)phosphino)-4-methylbenzenesulfonate (counted as Pd atoms), and the premix are added into the reactor. The temperature in the reactor is set to 80 °C, ethylene is continuously introduced into the reactor, and the reactor pressure is set to 10 bar. After half an hour, the addition of ethylene is stopped, and acidified ethanol is injected to terminate the reaction. After depressurization, the reaction solution is poured into a flask, the solvent and unreacted monomers are evaporated, and it is placed in a vacuum oven and dried at 70 °C for 24 hours. The polymerization results and characterization data are shown in Table 2, and the activity without adding Component b is used as the comparative data.

[0085] Table 2

[0086]

[0087] Examples 9 - 12

[0088] This example is used to illustrate the ethylene / acrylic acid (ester) copolymer of the present invention and its preparation method, and to test the effect of the addition amount of different components b on polymerization. The preparation is carried out in a 1.8 L reactor, which is equipped with a mechanical stirrer and a jacket, connected to an ethylene pipeline, and the reaction temperature is controlled by the oil bath temperature in the jacket.

[0089] The preparation method is as follows:

[0090] (1) According to the dosage in Table 3, methyl acrylate (MA) and 2,6-di-tert-butyl-4-methylphenol (component b) are premixed for 2.5 minutes to obtain a premix.

[0091] (2) 1000 mL of toluene, 140 μmol of palladium 2-(bis(2-methoxyphenyl)phosphino)-4-methylbenzenesulfonate (calculated as Pd atoms) and the premix are added into the reactor. The temperature in the reactor is set to 80 °C, ethylene is continuously introduced into the reactor, and the reactor pressure is set to 10 bar. After half an hour, the addition of ethylene is stopped, and acidified ethanol is injected to terminate the reaction. After depressurization, the reaction solution is poured into a flask, the solvent and unreacted monomers are evaporated, and it is placed in a vacuum oven and dried at 70 °C for 24 hours. The polymerization results and characterization data are shown in Table 3.

[0092] Table 3

[0093]

[0094] Example 16

[0095] The copolymer is prepared according to the method of Example 1, except that the comonomer is an equimolar amount of acrylic acid. The polymerization results and characterization data are shown in Table 4, and the activity without adding component b is used as the comparative data.

[0096] Example 17

[0097] The copolymer is prepared according to the method of Example 1, except that the comonomer is an equimolar amount of methyl methacrylate. The polymerization results and characterization data are shown in Table 4, and the activity without adding component b is used as the comparative data.

[0098] Example 18

[0099] The copolymer was prepared according to the method of Example 1, except that the comonomer was 2-ethylhexyl methacrylate in equimolar amounts. The polymerization results and characterization data are shown in Table 4, with the activity without Component b as the comparative data.

[0100] Examples 19 - 21

[0101] The copolymer was prepared according to the methods of Examples 1-3, except that Component b used was 2,6-di-tert-butyl-α-(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadienylidene)-p-tolyloxy radical. The polymerization results and characterization data are shown in Table 4, with the activity without Component b as the comparative data.

[0102] Examples 22 - 23

[0103] The copolymer was prepared according to the methods of Examples 1-2, except that the comonomer and Component b were not premixed, but the respective components were directly added to the reactor for mixing. The polymerization results and characterization data are shown in Table 4, with the activity without Component b as the comparative data.

[0104] Examples 24 - 25

[0105] The copolymer was prepared according to the methods of Examples 5-6, except that the comonomer and Component b were not premixed, but the respective components were directly added to the reactor for mixing. The polymerization results and characterization data are shown in Table 4, with the activity without Component b as the comparative data.

[0106] Example 26

[0107] The copolymer was prepared according to the method of Example 2, except that the temperature of the polymerization reaction was 100 °C and the pressure was 1.2 MPa.

[0108] Example 27

[0109] The copolymer was prepared according to the method of Example 2, except that the temperature of the polymerization reaction was 60 °C and the pressure was 0.8 MPa.

[0110] Example 28

[0111] The copolymer was prepared according to the method of Example 2, except that Component a used was palladium 2-(bis(2-methoxyphenyl)phosphino)benzenesulfonate (PSPd-1). The polymerization results and characterization data are shown in Table 4, with the activity without Component b as the comparative data.

[0112] Example 29

[0113] The copolymer was prepared according to the method of Example 2, except that component a used was palladium 2-(bis(2-phenoxyphenyl)phosphino)benzenesulfonate. The polymerization results and characterization data are shown in Table 4, and the activity without adding component b was used as the comparative data.

[0114] Example 30

[0115] The copolymer was prepared according to the method of Example 2, except that component b used was 2,6-di-tert-butylphenol. The polymerization results and characterization data are shown in Table 4, and the activity without adding component b was used as the comparative data.

[0116] Example 31

[0117] The copolymer was prepared according to the method of Example 2, except that component b used was 2,4,6-tri-tert-butylphenol. The polymerization results and characterization data are shown in Table 4, and the activity without adding component b was used as the comparative data.

[0118] Table 4

[0119]

[0120]

[0121] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

[0122] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the values between the endpoints of each range, between the endpoints of each range and a single point value, and between single point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

Claims

1. A catalyst system for copolymerization of ethylene and polar monomers, characterized in that, the catalyst system consists of the following components: Component a, the main catalyst, selected from at least one of the compounds represented by formula (I), In formula (I), R 1 , R 2 , R 3 are the same or different and each independently is a hydrogen atom, a substituted or unsubstituted C 1 -C 20 hydrocarbyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group or a substituted or unsubstituted C 6 -C 20 aryloxy group, these groups being linear, branched or cyclic and optionally further substituted by a halogen atom, a C 1 -C 10 alkyl group, a C 1 -C 10 alkoxy group, a C 6 -C 10 aryl group or a C 6 -C 10 aryloxy group, and L is a ligand; Component b, selected from at least one of the compounds represented by formula (II) and the compounds represented by formula (III): In formula (II), R 4 is selected from a hydrogen atom, a substituted or unsubstituted C 1 -C 20 hydrocarbyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group or a substituted or unsubstituted C 6 -C 20 aryloxy group, these groups being linear, branched or cyclic and optionally further substituted by a halogen atom, a C 1 -C 10 alkyl group, a C 1 -C 10 alkoxy group, a C 1 -C 6 carbonyl group, a C 6 -C 10 aryl group or a C 6 -C 10 aryloxy group; In formula (III), R 5 is selected from a hydrogen atom, a substituted or unsubstituted C 1 -C 20 hydrocarbyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group or a substituted or unsubstituted C 6 -C 20 aryloxy group, these groups being linear, branched or cyclic and optionally further substituted by a halogen atom, a C 1 -C 10 alkyl group, a C 1 -C 10 alkoxy group, a C 1 -C 6 carbonyl group, a C 6 -C 10 aryl group or a C 6 -C 10 aryloxy group.

2. The catalyst system according to claim 1, wherein, In formula (I), R 1 , R 2 , R 3 are the same or different and each independently is a hydrogen atom, a substituted or unsubstituted C 1 -C 10 hydrocarbyl group, a substituted or unsubstituted C 1 -C 10 alkoxy group or a substituted or unsubstituted C 6 -C 10 aryloxy group, and these groups are linear, branched or cyclic and are optionally further substituted by a halogen atom, a C 1 -C 6 alkyl group, a C 1 -C 6 alkoxy group, a C 6 -C 8 aryl group or a C 6 -C 8 aryloxy group, L is Me 2 SO; preferably, R 1 , R 2 , R 3 are the same or different and each independently is a hydrogen atom, a substituted or unsubstituted C 1 -C 6 alkyl group, a substituted or unsubstituted C 1 -C 6 alkoxy group or a substituted or unsubstituted C 6 -C 8 aryloxy group, and these groups are linear, branched or cyclic and are optionally further substituted by a halogen atom, a C 1 -C 6 alkyl group, a C 1 -C 6 alkoxy group, a C 6 -C 8 aryl group or a C 6 -C 8 aryloxy group.

3. The catalyst system according to claim 2, wherein, Component a is at least one of palladium 2-(bis(2-methoxyphenyl)phosphino)benzenesulfonate, palladium 2-(bis(2-phenoxyphenyl)phosphino)benzenesulfonate, and palladium 2-(bis(2-methoxyphenyl)phosphino)-4-methylbenzenesulfonate.

4. The catalyst system according to claim 1, wherein, In formula (II), R 4 is selected from a hydrogen atom, a substituted or unsubstituted C 1 -C 10 alkyl group, a substituted or unsubstituted C 8 -C 16 conjugated cycloalkyl group, a substituted or unsubstituted C 1 -C 10 alkoxy group or a substituted or unsubstituted C 6 -C 10 aryloxy group, and is optionally further substituted by a halogen atom, a C 1 -C 6 alkyl group, a C 1 -C 6 alkoxy group, a C 1 -C 3 carbonyl group, a C 6 -C 8 aryl group or a C 6 -C 8 aryloxy group; In formula (III), R 5 is selected from a hydrogen atom, a substituted or unsubstituted C 1 -C 10 alkyl group, a substituted or unsubstituted C 8 -C 16 conjugated cycloalkyl group, a substituted or unsubstituted C 1 -C 10 alkoxy group or a substituted or unsubstituted C 6 -C 10 aryloxy group, and is optionally further substituted by a halogen atom, a C 1 -C 6 alkyl group, a C 1 -C 6 alkoxy group, a C 1 -C 3 carbonyl group, a C 6 -C 8 aryl group or a C 6 -C 8 aryloxy group.

5. The catalyst system according to claim 4, wherein, Component b is at least one of 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol, and 2,6-di-tert-butyl-α-(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadienylidene)-p-tolyloxy radical.

6. The catalyst system according to any one of claims 1-5, wherein, the molar ratio of Component a to Component b based on Pd atoms is 1:1 to 1:200, preferably 1:3 to 1:100, more preferably 1:4 to 1:50, and further preferably 1:5 to 1:

30.

7. Use of the catalyst system according to any one of claims 1-6 in the copolymerization reaction of ethylene and polar monomers.

8. A method for preparing an ethylene / acrylic acid (ester) copolymer, characterized in that, the preparation method includes: in the presence of a catalyst system, subjecting ethylene and an acrylic acid (ester) monomer to a polymerization reaction in an inert solvent to obtain an ethylene / acrylic acid (ester) copolymer; the catalyst system is the catalyst system according to any one of claims 1-6; the acrylic acid (ester) monomer is at least one of the compounds represented by formula (A), In formula (A), R a is a hydrogen atom, a linear or branched C 1 -C 4 alkyl group, and R b is a hydrogen atom, a linear or branched C 1 -C 10 alkyl group.

9. The preparation method according to claim 8, wherein, In formula (A), R a is a hydrogen atom or a methyl group, and R b is a hydrogen atom, a linear or branched C 1 -C 8 alkyl group; preferably, the acrylic acid (ester) monomer is at least one of acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, and 2-ethylhexyl methacrylate.

10. The preparation method according to claim 8, wherein, The inert solvent is an aliphatic hydrocarbon solvent and / or an aromatic hydrocarbon solvent; preferably a straight-chain, branched-chain or cyclic C 6 -C 12 alkane and / or C 6 -C 10 monocyclic aromatic hydrocarbon; the C 6 -C 12 alkane is preferably at least one of n-hexane, iso-hexane, n-heptane, iso-heptane, n-octane, iso-octane and cyclohexane; the C 6 -C 10 monocyclic aromatic hydrocarbon is preferably toluene and / or xylene; preferably, the inert solvent is at least one of n-hexane, iso-hexane, cyclohexane and toluene.

11. The preparation method according to claim 8, wherein, in the polymerization reaction system, the concentration of the acrylic acid (ester) monomer is 5 mol / L or less, preferably 2 mol / L or less, and more preferably 1 mol / L or less.

12. The preparation method according to claim 8, wherein, the acrylic acid (ester) monomer is premixed with Component b in the catalyst system, and the premixing time is preferably 1 to 30 minutes, more preferably 2 to 15 minutes, and further preferably 3 to 10 minutes.

13. The preparation method according to claim 8, wherein, the molar ratio of the acrylic acid (ester) monomer to component b in the catalyst system is 50:1 to 800:1, preferably 100:1 to 350:1, more preferably 150:1 to 300:

1.

14. The preparation method according to any one of claims 8-13, wherein, the temperature of the polymerization reaction is 20 to 150 °C, preferably 40 to 120 °C, more preferably 60 to 100 °C; the pressure of the polymerization reaction is below 10 MPa, preferably 0.01 to 5 MPa, more preferably 0.1 to 2 MPa.

15. An ethylene / acrylic acid (ester) copolymer prepared by the preparation method according to any one of claims 8-14.

16. The ethylene / acrylic acid (ester) copolymer according to claim 15, wherein, the copolymer comprises 75 to 99 mol% of structural units derived from ethylene and 1 to 25 mol% of structural units derived from acrylic acid (ester) monomers; the proportion of acrylic acid (ester) inserted into the main chain of the copolymer is above 70 mol%, preferably above 80 mol%, further preferably above 85 mol%, more preferably above 90 mol%.

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