Supported late transition metal catalysts for ethylene polymerization and in situ grafting, and methods of making and using the same

Abstract

The present application relates to a kind of supported post-transition metal catalyst for ethylene polymerization and in situ grafting and its preparation method and application.The supported post-transition metal catalyst includes the blending component and / or reaction product of the following raw materials: carrier, post-transition metal catalyst, activator and radical initiator, and the activator is organic aluminum compound.In the loading process, radical initiator is added, and the supported post-transition metal catalyst particles are formed by spray drying, the particle size is adjustable, the particle shape is good, the particle size distribution is narrower, it is easier to control, so as to prepare smaller polyethylene particles, and then it is beneficial to improve the grafting reaction rate.The catalyst and polymerization method can directly obtain grafted polyethylene by one-step method, and do not need drying and separation, simplify the preparation process of grafted polyethylene, the amount of initiator and polar monomer is less, grafting reaction is more uniform, grafting rate is higher, and side reaction is less.Powder has good particle morphology, and the bulk density is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polyolefin catalysts, in particular to a supported post-transition metal catalyst for olefin polymerization and in-situ grafting, and a preparation method and application thereof. BACKGROUND

[0002] Polyethylene is the most common general-purpose plastic, but its application is limited due to its complete lack of polarity. In order to expand the application range and improve the processing and performance, it is usually necessary to carry out processing modification to introduce polar groups into the molecular chain.

[0003] Catalysts are the core technology of the polyolefin industry, and post-transition metals generally refer to metal elements (such as Ni, Pd, Pt, Co, Fe, Ru, Rh, Cu) in the right half of the transition metal group of the periodic table of elements. In 1995, Brookhart et al. reported a class of post-transition metal catalysts, which have unique "chain walking" characteristics, can produce branched polyethylene without adding comonomers, and can control the branching degree of the polymer by controlling temperature and pressure, which has attracted great attention. After being supported, not only can it maintain its catalytic characteristics, improve the morphology of the polymer and increase the bulk density, but also it can adapt to the existing slurry polymerization process device.

[0004] The currently commonly used polyethylene grafting methods are mainly: 1. Melt grafting method. This is the most commonly used and most researched chemical grafting method at present, in which the polyethylene in a molten state is grafted with grafting monomers in an extruder under the action of an initiator; 2. Solution grafting method. It refers to dissolving polyethylene, polar monomer and initiator in a reaction medium for grafting reaction; 3. Solid phase grafting method. It is to directly place polyethylene powder with initiator, grafting monomer, surfactant, etc. together for contact reaction; 4. Radiation grafting method. This method uses high-energy gamma rays or ultraviolet rays as radiation energy source, the irradiated polyethylene generates free radicals, which are then polymerized with grafting monomers to obtain grafted free radical initiators (Plastics Technology, 2005(2): 42-46). The above methods are all secondary reactions of finished polyethylene to obtain grafted polyethylene.

[0005] The melt method has large equipment investment and high gel content due to high preparation temperature; the solid phase grafting method has many advantages such as simple operation, short reaction time, low investment, no need of reaction medium and no need of solvent recovery, and has high practical value. However, the method also has disadvantages: the reaction is a heterogeneous system and is a local modification method, thus being prone to problems such as uneven grafting and low grafting rate, and the radiation method also has such problems; and the solution method is a homogeneous system and can obtain uniform grafting products, but the products need to be dried and separated, and the operation is complicated and not environment-friendly. SUMMARY

[0006] Based on this, the application provides a post-transition metal catalyst for ethylene polymerization and in-situ grafting and a preparation method thereof. The catalyst introduces a free radical initiator in the preparation process, and the preparation process is relatively simple. Firstly, the post-transition metal catalyst is responsible for catalyzing ethylene polymerization, at this time, the free radical initiator is uniformly dispersed in the polyethylene powder, and then the free radical initiator initiates the grafting of polar monomers on the polyethylene, the grafting reaction is more uniform, the amount of free radical initiator is less, the grafting rate is more efficient, and due to the special “chain walking” behavior of the post-transition metal catalyst, the branching degree and molecular weight of polyethylene can be adjusted by adjusting the catalyst ligand structure, polymerization temperature and pressure, so that polyethylene which is more easily grafted can be obtained, and the adjustability is high. In addition, the catalyst is prepared by using a spray drying method, the catalyst has good particle shape, and the particle size of the catalyst can be adjusted according to the use requirement, and the grafting rate is improved. The catalyst is used, and grafted polyethylene can be directly obtained by one-step method, the product does not need to be dried and separated, the polymer powder has high bulk density, and the preparation process of the grafted polyethylene is simplified.

[0007] The first aspect of the application is to provide a supported post-transition metal catalyst, which comprises the following blending components and / or reaction products of raw materials: a carrier, a post-transition metal catalyst, an activator and a free radical initiator, and the activator is an organic aluminum compound.

[0008] According to the application, the carrier can be selected in a wide range, and in a preferred embodiment of the application, the carrier is selected from inorganic oxide carriers, preferably silicon oxide and / or aluminum oxide, and more preferably silicon dioxide.

[0009] According to the application, preferably, the particle size of the carrier is 0.01-5 μm, and preferably 0.01-2 μm.

[0010] According to the present application, the free radical initiator can be selected in a wide range, in a preferred embodiment of the present application, the free radical initiator is selected from at least one of azo type, peroxide type initiator, preferably selected from at least one of benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, tert-butyl benzene peroxide, diisobutyl peroxide, azobisisobutyronitrile, azobisisoheptyl nitrile.

[0011] According to the present application, the organic aluminum compound can be selected in a wide range, in a preferred embodiment of the present application, the organic aluminum compound is AlR n X (3-n) or containing a compound having the structure, wherein R is an alkyl group with a carbon atom number of 1-10, X is halogen, n is an integer of 1-3; more preferably, the organic aluminum compound is selected from at least one of trimethylaluminum, triethylaluminum, methylaluminoxane, monochlorodiethylaluminum, dichloroethylaluminum, tri-n-butylaluminum, triisobutylaluminum, hemimethylaluminum chloride, hemiethylaluminum chloride.

[0012] According to the present application, the late transition metal catalyst can be selected in a wide range, for the above-mentioned late transition metal catalyst, the present application can be obtained by the method in the prior art, for example, the diamine complex described in CN111116787A, the diimine metal complex described in CN112745362A, the late transition metal catalyst in CN114478868A, CN104059175A, CN104059175B, etc.

[0013] In the present application, the above-mentioned late transition metal catalyst is prepared based on the method disclosed in the references Polymers 2018, 10, 2073-4360, Macromolecules 2014, 47, 3325-3331, Angew. Chem., Int. Ed. 2004, 43, 1821-1825, J. Am. Chem. Soc. 2014, 136, 7213 7216, etc. The related contents disclosed in the above-mentioned documents can be all incorporated into the present application as reference, which will not be repeated here.

[0014] In a preferred embodiment of the present application, the late transition metal catalyst has the structure as formula (I):

[0015]

[0016] formula (I);

[0017] In formula (I), R1to R2are each selected from hydrogen or an alkyl group or an aryl group having 1 to 20 carbon atoms, and are preferably each selected from at least one of hydrogen, an alkyl group having 1 to 10 carbon atoms, and an aryl group having 6 to 10 carbon atoms;

[0018] R3to R8are each selected from hydrogen or an alkyl group or an aryl group having 1 to 20 carbon atoms, and are preferably each selected from at least one of hydrogen, an alkyl group having 1 to 10 carbon atoms, and an aryl group having 6 to 10 carbon atoms;

[0019] X1and X2are halogen, and are preferably each selected from at least one of chlorine, bromine, and iodine;

[0020] M is Fe, Co, or Ni.

[0021] In a preferred embodiment of the present application, the content of the post-transition metal M in the supported post-transition metal catalyst is 0.1 to 5% by weight, for example, can be any value or a range between any two values selected from the group consisting of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%, based on 100% by weight of the total mass of the supported post-transition metal catalyst, and is preferably 0.3 to 3% by weight.

[0022] In a preferred embodiment of the present application, the content of the radical initiator is 10 to 60% by weight, for example, can be any value or a range between any two values selected from the group consisting of 10%, 20%, 30%, 40%, 50%, and 60%, based on 100% by weight of the total mass of the supported post-transition metal catalyst, and is preferably 20 to 40% by weight.

[0023] In a preferred embodiment of the present application, the molar ratio of aluminum in the organoaluminum compound to the post-transition metal element M is (5 to 500): 1, for example, can be any ratio or a range between any two ratios selected from the group consisting of 5:1, 10:1, 50:1, 100:1, 300:1, and 500:1, and is preferably (20 to 200): 1.

[0024] In a more preferred embodiment of the present application, the content of the post-transition metal M in the supported post-transition metal catalyst is 0.1 to 5% by weight, and is preferably 0.3 to 3% by weight, and / or the content of the radical initiator is 10 to 60% by weight, and is preferably 20 to 40% by weight, based on 100% by weight of the total mass of the supported post-transition metal catalyst; and the molar ratio of aluminum in the organoaluminum compound to the post-transition metal element M is (5 to 500): 1, and is preferably (20 to 200): 1.

[0025] In a preferred embodiment of the present application, the average particle size of the supported post-transition metal catalyst is 7-100 μm. The inventors of the present application have found that, based on the formulation of the catalyst in the present application (i.e. the support, the post-transition metal catalyst, the activator (which is an organoaluminum compound) and the free radical initiator), by further adjusting the average particle size of the supported post-transition metal catalyst, the grafting rate of the grafted polyethylene can be adjusted while maintaining a certain polymerization activity. Within the above preferred average particle size range, grafted polyethylene with a high grafting rate can be obtained. More preferably, the average particle size of the supported post-transition metal catalyst is 8-30 μm, which can further improve the grafting rate. Still more preferably, the average particle size of the supported post-transition metal catalyst is 8-20 μm. Most preferably, the average particle size of the supported post-transition metal catalyst is 8-15 μm. Under the condition of a still lower average particle size, the grafted polyethylene has a still higher grafting rate.

[0026] In a more preferred embodiment of the present application, the post-transition metal catalyst in the formulation of the supported catalyst is selected from catalyst 1 in the examples. The structure of catalyst 1 is more prone to "chain walking" of the polymer chains during polymerization, which improves the degree of polymer branching and thus has a higher grafting rate.

[0027] According to the present application, in order to further improve the uniformity of the particle size of the obtained grafted polyethylene and make the particle size distribution narrower, in a preferred embodiment of the present application, the particle size distribution of the supported post-transition metal catalyst is less than 2, more preferably less than 1.5.

[0028] In the present application, the particle size refers to the average particle size, i.e. the equivalent diameter of the largest particle when the cumulative distribution is 50% in the particle size distribution curve (d 50 ). The particle size distribution refers to the span, i.e. (d 90 -d 10 ) / d 50 ), which describes the extent of the range of particle distribution.

[0029] The second aspect of the present application is to provide a preparation method of the supported post-transition metal catalyst of the first aspect, comprising the following steps:

[0030] (1) dispersing components comprising the post-transition metal catalyst, the activator, the support and the free radical initiator in an organic solvent to form a slurry;

[0031] (2) spray drying the slurry obtained in step (1) to obtain the supported post-transition metal catalyst.

[0032] According to a preferred embodiment of the present application, the preparation of the slurry in step (1) comprises: dissolving the radical initiator, the late transition metal catalyst and the activator in the organic solvent, and then adding the support; more preferably, the radical initiator, the late transition metal catalyst and the activator are first dissolved in the organic solvent, and then the support is added at 20-45°C and mixed for 2-12 hours. More preferably, the dissolution conditions are constant temperature at 20-40°C for 0.5-3 hours.

[0033] According to the specific embodiment of the present application, in step (2), the spray drying can use the spray drying equipment and process conditions commonly used in the art. According to a preferred embodiment of the present application, the spray drying conditions in step (2) are: inlet temperature 50-200°C, and outlet temperature 30-150°C.

[0034] According to the present application, the particle size of the obtained catalyst can be adjusted by adjusting the inlet gas flow rate of the spray drying nozzle. According to a preferred embodiment of the present application, the inlet gas flow rate of the spray drying nozzle in step (2) is 10-50 m 3 / h, more preferably 21-50 m 3 / h, and still more preferably 26-50 m 3 / h.

[0035] In a preferred embodiment of the present application, the organic solvent is selected from at least one of alkanes, halogenated alkanes, aromatic hydrocarbons, heterocyclic compounds, ethers, ketones, and esters, and more preferably is selected from at least one of pentane, hexane, heptane, dichloromethane, trichloromethane, benzene, toluene, chlorobenzene, chlorotoluene, tetrahydrofuran, acetone, diethyl ether, and ethyl acetate.

[0036] In a preferred embodiment of the present application, the amount of the organic solvent is 5-100 mL, and preferably 10-50 mL, relative to 1 g of the support.

[0037] According to the present application, the amounts of the raw materials can be selected within a wide range. In a preferred embodiment of the present application, the amount of the late transition metal catalyst is 0.01-1 parts, the amount of the activator is 0.1-30 parts, and the amount of the radical initiator is 0.02-10 parts, relative to 1 part of the support, in terms of mass parts; more preferably,

[0038] In terms of mass parts, the amount of the late transition metal catalyst is 0.05-0.5 parts, the amount of the activator is 0.3-10 parts, and the amount of the radical initiator is 0.1-3 parts, relative to 1 part of the support, and more preferably the amount of the radical initiator is 0.8-3 parts.

[0039] The third aspect of the present application provides the use of the supported post-transition metal catalyst of the first aspect or the supported post-transition metal catalyst prepared by the method of the second aspect in olefin polymerization, preferably in ethylene polymerization and in situ grafting.

[0040] In a preferred embodiment of the present application, the use of the supported post-transition metal catalyst in olefin polymerization, i.e. the method of ethylene polymerization and in situ grafting, comprises:

[0041] 1) contacting ethylene with the supported post-transition metal catalyst to perform ethylene polymerization to obtain a polyethylene powder containing a free radical initiator, wherein the free radical initiator is uniformly dispersed in the polyethylene powder;

[0042] 2) contacting a polar monomer for grafting with the polyethylene powder containing the free radical initiator obtained in 1) to initiate in situ grafting of the polar monomer on the polyethylene by the free radical initiator.

[0043] Preferably, the polar monomer is a compound containing a double bond and containing a polar group, more preferably at least one of acrylic acid and its derivatives or esters, maleic anhydride or ester, maleate, alkenyl bisphenol A ether, propylene cyanide, styrene and its homologues, and glycidyl methacrylate.

[0044] The method of ethylene polymerization and in situ grafting in the present application includes but is not limited to ethylene slurry polymerization and grafting reaction.

[0045] As an example, in the ethylene slurry polymerization and grafting reaction, the conditions of the ethylene polymerization include:

[0046] The temperature is 30-90°C, the reaction time is 0.5-3h, the pressure is 0.1-5MPa, and the amount of the supported post-transition metal catalyst is 20-500mg; preferably in the presence of alkyl aluminum or methylaluminoxane.

[0047] The alkyl aluminum can be selected from at least one of ethyl aluminum sesquichloride, triethyl aluminum, tri-n-hexyl aluminum, triisobutyl aluminum, and tri-n-octyl aluminum, and / or the amount of the alkyl aluminum or methylaluminoxane is 5-1000mol relative to 1mol of the metal element content in the supported post-transition metal catalyst. The alkyl aluminum or methylaluminoxane functions to (1) remove water and oxygen in the reaction process as a deactivator to avoid interference with the polymerization reaction; and (2) activate the catalyst to perform polymerization.

[0048] The conditions of the ethylene polymerization are such that the content of the free radical initiator in the obtained polyethylene powder containing the free radical initiator is 0.1-10wt%.

[0049] As an example, in the ethylene slurry polymerization and grafting reaction, the conditions of in-situ grafting reaction include:

[0050] The temperature is 80-150℃, the reaction time is 2-8h, the pressure is 1-5MPa, the mass ratio of polyethylene powder containing free radical initiator and polar monomer is 100-3:1.

[0051] The application provides a post-transition metal catalyst for ethylene polymerization and in-situ grafting and a preparation method thereof, the free radical initiator is introduced in the preparation process, the preparation process is relatively simple, the post-transition metal catalyst is responsible for catalyzing ethylene polymerization at first, at this time, the free radical initiator is uniformly dispersed in the polyethylene powder, and then the free radical initiator initiates the grafting of the polar monomer on the polyethylene, the grafting reaction is more uniform, the amount of the free radical initiator is small, the grafting efficiency is higher, and due to the special 'chain walking' behavior of the post-transition metal catalyst, the branching degree and molecular weight of the polyethylene can be regulated by adjusting the catalyst ligand structure, the polymerization temperature and the pressure, so that the polyethylene which is more easily grafted can be obtained, and the adjustability is high; in addition, the catalyst is prepared by using the spray drying method, the catalyst has good particle shape, and the particle size of the catalyst can be adjusted according to the use requirement, so that the grafting rate is improved. The grafted polyethylene can be directly obtained by using the catalyst through a one-step method, the product does not need to be dried and separated, the polymer powder has high bulk density, and the preparation process of the grafted polyethylene is simplified.

[0052] Compared with the prior art, the application has the following advantages:

[0053] (1) The supported post-transition metal catalyst for ethylene polymerization and in-situ grafting provided by the application adds the free radical initiator in the loading process, the free radical is uniformly dispersed in the polyethylene after the ethylene polymerization is initiated, and then the in-situ polar monomer grafting is initiated, so that the polar grafted polyethylene can be directly obtained through a one-step method;

[0054] (2) The supported post-transition metal catalyst for ethylene polymerization and in-situ grafting provided by the application adds the free radical initiator in the loading process, the free radical is uniformly dispersed in the polyethylene after the ethylene polymerization is initiated, and then the in-situ polar monomer grafting is initiated, so that the amount of the initiator is small, the grafting reaction is more uniform, and the grafting rate is higher;

[0055] (3) The catalyst prepared by using the supported post-transition metal catalyst has good particle morphology, high bulk density and does not need to be dried and separated, and can be used in the slurry polymerization process.

[0056] (4) The special "chain walking" behavior of the supported transition metal catalyst used in the present application for catalyzing ethylene polymerization makes it possible to control the branching degree and molecular weight of polyethylene by adjusting the catalyst ligand structure, polymerization temperature and pressure, etc., so that the polyethylene obtained by polymerization is more easily polar grafted, the occurrence of side reactions is reduced, and the adjustability is high;

[0057] (5) The preparation method of the supported transition metal catalyst provided by the present application for ethylene polymerization and in-situ grafting is simple, the catalyst particle morphology is good, the particle size is adjustable within a large range, the particle size distribution is narrow, the catalyst particle size can be adjusted according to the use requirement, the polyethylene powder particle size is reduced, and the grafting rate is improved. DETAILED DESCRIPTION

[0058] It is necessary to point out here that the following examples are only used to further illustrate the present application and cannot be understood as limiting the protection scope of the present application. Some non-essential improvements and adjustments to the present application made by those skilled in the art according to the content of the present application still fall within the protection scope of the present application.

[0059] The test instruments and test conditions used in the examples are as follows:

[0060] Grafting rate (DG) determination: 0.5 g of the grafted sample was heated to reflux and dissolved in 70 mL of xylene, 15 mL of KOH-methanol standard solution was added while hot, and refluxing was continued for 2 h, 2 drops of phenolphthalein reagent were added, and standard HCl-isopropyl alcohol solution was titrated, while a blank sample was titrated, and the grafting rate was calculated. The mass of maleic anhydride contained in every 100 g of the sample was calculated.

[0061] Gel content (DC) determination: a small amount of the grafted sample was packed into a filter bag, placed in a Soxhlet extractor, and refluxed and extracted with xylene for 12 h or more, then the filter bag was taken out and dried in an oven at 80°C until the mass was constant, and the DC was calculated as the mass of gel contained in 100 g of the sample (g), as shown in formula (1).

[0062] DC = (m3-m2) / (m1-m2) (1)

[0063] In the formula, m1 is the mass of the filter bag after the sample is packed, g; m2 is the mass of the filter bag, g; and m3 is the total mass after extraction and drying, g.

[0064] Particle size and particle size distribution: Malvern MS3000 laser particle size distribution instrument was used to test the particle size and particle size distribution of the catalyst;

[0065] Metal content: inductively coupled plasma mass spectrometer ICP-MS (Agilent 7500CX) was used to test the metal content in the catalyst.

[0066] Determination of initiator content in catalyst: liquid nuclear magnetic resonance (Bruker AVANCE 300) was used to determine the content of hydroquinone as internal standard.

[0067] Density test: gradient tube method, test method GB 1033 BHU.

[0068] The sources of raw materials used in the examples are as follows:

[0069] Synthesis of post-transition metal catalyst 1:

[0070] Acenaphthenequinone 7.4 mmol was heated to reflux for 30 minutes with 65 mL of acetonitrile, 12 mL of formic acid was added to the reaction solution, and heating was continued until acenaphthenequinone was completely dissolved. Then 16 mmol of 2,6-diethyl aniline / 2,6-dimethyl aniline was added, and heating was continued for 3 hours. After the reaction was completed, the reaction solution was cooled to room temperature, concentrated, and recrystallized with hexane to obtain an orange-red solid with a yield of 88%. The product was dried.

[0071] The obtained ligand was added to a Schlenk flask with an equal molar amount of (DME)NiBr2, dichloromethane was used as the solvent, and stirring was carried out at room temperature for 12 h. The reaction solution was concentrated and recrystallized with ether or hexane to obtain the nickel complex with a yield of 80%.

[0072]

[0073] Post-transition metal catalyst 1

[0074] Synthesis of post-transition metal catalyst 2:

[0075] According to the synthesis steps of post-transition metal catalyst 1, 2,6-diethyl aniline was replaced by 2,4,6-dimethyl aniline to obtain post-transition metal catalyst 2.

[0076]

[0077] Post-transition metal catalyst 2

[0078] The other raw materials used in the examples of the present application are commercially available products.

[0079] Example 1

[0080] 1. Preparation of supported catalyst: 6.0 g of benzoyl peroxide, 0.66 g of post-transition metal catalyst 1, and 40 mL of 1 mol / L molar concentration of aluminum chloride hexane solution were dissolved in 100 mL of dichloromethane at room temperature under nitrogen protection. After dissolution, 6 g of silica (particle size 0.01-2 μm) was added, and stirring was carried out for 2 h. Then, spray drying was carried out using a spray dryer. The spray conditions were: inlet temperature 70°C, outlet temperature 40°C, and nitrogen flow rate at the inlet 31.0 m3 / h, to obtain 12.2 g of catalyst. Some of its physical property parameters are shown in Table 1.

[0081] 2. Ethylene slurry polymerization and grafting reaction: 1 L of hexane was added to a 2 L polymerizer which had been purged with nitrogen first and then hydrogen, and 1 mL of triethyl aluminum (1 M) and 100 mg of dry catalyst were added. Ethylene was added to 1.03 MPa, and the temperature was raised to 50°C. After 1 h of reaction at constant temperature and pressure, the ethylene in the polymerizer was replaced with nitrogen, and the pressure was raised to 2 MPa. Then 6.0 g of methacrylic acid was added, the temperature was raised to 130°C, and the reaction was carried out for 5 h. After the temperature was lowered, the product was discharged. The results are shown in Table 2.

[0082] Example 2

[0083] 1. Preparation of supported catalyst: 6.0 g of benzoyl peroxide, 1.32 g of post-transition metal catalyst 1, and 60 mL of 1 mol / L aluminum sesquichloride hexane solution were dissolved in 100 mL of dichloromethane at room temperature under nitrogen protection. After dissolution, 6.0 g of silica (particle size 0.01-2 μm) was added, and the mixture was stirred for 2 h. Then spray drying was carried out using a spray dryer. The spray conditions were: inlet temperature 70°C, outlet temperature 41°C, and nitrogen flow rate at inlet 31.0 m 3 / h, to obtain 12.6 g of catalyst. Some of its physical property parameters are shown in Table 1.

[0084] 2. Ethylene slurry polymerization and grafting reaction: 1 L of hexane was added to a 2 L polymerizer which had been purged with nitrogen first and then hydrogen, and 1 mL of triethyl aluminum (1 M) and 100 mg of dry catalyst were added. Ethylene was added to 1.03 MPa, and the temperature was raised to 50°C. After 1 h of reaction at constant temperature and pressure, the ethylene in the polymerizer was replaced with nitrogen, and the pressure was raised to 2 MPa. Then 6.0 g of methacrylic acid was added, the temperature was raised to 130°C, and the reaction was carried out for 5 h. After the temperature was lowered, the product was discharged. The results are shown in Table 2.

[0085] Example 3

[0086] 1. Preparation of supported catalyst: 6.0 g of benzoyl peroxide, 1.32 g of post-transition metal catalyst 1, and 60 mL of 1 mol / L aluminum sesquichloride hexane solution were dissolved in 100 mL of dichloromethane at room temperature under nitrogen protection. After dissolution, 6.0 g of silica (particle size 0.01-2 μm) was added, and the mixture was stirred for 2 h. Then spray drying was carried out using a spray dryer. The spray conditions were: inlet temperature 70°C, outlet temperature 41°C, and nitrogen flow rate at inlet 31.0 m 3 / h, to obtain 12.6 g of catalyst. Some of its physical property parameters are shown in Table 1.

[0087] 2. Ethylene slurry polymerization and grafting reaction: 1 L hexane was added into a 2 L polymerizer which was first purged with nitrogen and then with hydrogen, and 1 mL triethylaluminum (1 M) and 100 mg dry catalyst were added. Ethylene was added to 1.03 MPa, and the temperature was raised to 50°C. After 1 h of reaction at 50°C and constant pressure, the ethylene in the polymerizer was replaced with nitrogen, and the pressure was raised to 2 MPa. Then 6.0 g of maleic anhydride diethyl ester was added, and the temperature was raised to 130°C. After 5 h of reaction, the temperature was lowered, and the product was discharged. The results are shown in Table 2.

[0088] Example 4

[0089] 1. Preparation of supported catalyst: 6.0 g of azobisisobutyronitrile, 0.61 g of late transition metal catalyst 2, and 30 mL of 10% methylaluminoxane dichloromethane solution were dissolved in 100 mL dichloromethane at room temperature under nitrogen protection. After dissolution, 6.0 g of silica (particle size 0.01-2 μm) was added, and the mixture was stirred for 2 h. Then spray drying was performed using a spray dryer. The spray conditions were: inlet temperature 70°C, outlet temperature 45°C, and nitrogen flow rate 25.0 m 3 / h. The catalyst was obtained in a yield of 12.5 g.

[0090] 2. Ethylene slurry polymerization and grafting reaction: 1 L hexane was added into a 2 L polymerizer which was first purged with nitrogen and then with hydrogen, and 1 mL triethylaluminum (1 M) and 100 mg dry catalyst were added. Ethylene was added to 1.03 MPa, and the temperature was raised to 50°C. After 45 min of reaction at 50°C and constant pressure, the ethylene in the polymerizer was replaced with nitrogen, and the pressure was raised to 2 MPa. Then 8.0 g of maleic anhydride diethyl ester was added, and the temperature was raised to 130°C. After 5 h of reaction, the temperature was lowered, and the product was discharged. The results are shown in Table 2.

[0091] Example 5

[0092] The catalyst was prepared according to the method of Example 1, except that the nitrogen flow rate was controlled to be 20.0 m 3 / h during spray drying. The catalyst was obtained in a yield of 8.1 g, and some of its physical property parameters are shown in Table 1.

[0093] Ethylene slurry polymerization and grafting reaction were performed according to the method of Example 1 to obtain a product sample, and the results are shown in Table 2.

[0094] Comparative Example 1

[0095] In a stainless steel reactor with a heating band and stirring, 50 g of high-density polyethylene, 4 g of methacrylic acid, 4 g of benzoyl peroxide, and an appropriate amount of interfacial wetting agent were added. The reaction temperature was set to 110°C, and the reaction was carried out for 3 h. After the reaction, the product was washed with xylene and anhydrous ethanol, and then filtered and dried to obtain a product sample. The physical properties of the product are shown in Table 2.

[0096] Comparative Example 2

[0097] In a stainless steel jacketed reactor with stirring, 50 g of high density polyethylene, 4 g of methacrylic acid, 4 g of azobisisobutyronitrile and a proper amount of interfacial wetting agent were added, the reaction temperature was set at 110°C, and the reaction was carried out for 3 h. After the reaction, the product was washed with xylene and anhydrous ethanol, and then filtered and dried to obtain a product sample, the physical properties of which are shown in Table 2.

[0098] Comparative Example 3

[0099] The catalyst was prepared according to the method of Example 1, except that no benzoyl peroxide was added, to obtain a supported transition metal catalyst 11.7 g. The partial physical property parameters of which are shown in Table 1.

[0100] Ethylene slurry polymerization and grafting reaction were carried out according to the method of Example 1, except that the polymerization reaction time was 45 min, and 6 g of benzoyl peroxide was added during the grafting reaction, together with the methacrylic acid, to obtain a product sample, the evaluation results of which are shown in Table 2.

[0101] Table 1. Physical parameters of supported transition metal catalysts

[0102]

[0103]

[0104] Table 2. Partial physical properties of grafted polyethylene

[0105]

[0106] As can be seen from the data in Table 1, the supported transition metal catalysts for ethylene polymerization and in-situ grafting obtained in Examples 1-4 can have their metal loading and free radical content adjusted according to the formulation, and the particle size can be controlled by the slurry formulation and process conditions, so that smaller polyethylene particles can be obtained, which is more conducive to improving the grafting reaction rate, and the particle size distribution is relatively narrow.

[0107] Example 5 is obtained by changing the spray drying conditions, and the catalyst size is larger (Table 1), and the polymer particle size obtained by such a catalyst is also larger. As can be seen by comparing Example 1, Example 5 will reduce the grafting efficiency, indicating the controllability of the catalyst particle size.

[0108] As can be seen from the data in Table 2, the initiator content in Examples 1-4 is much lower than that in the comparative examples, thus the gel content of the product is lower, and the post-transition metal catalyst has a "chain walking" effect, so that branched polyethylene can be obtained without adding a comonomer, and the grafting reaction of the second step is more easily initiated, thus improving the grafting efficiency; under the condition of less initiator and polar monomer, a one-step method can be used to directly obtain polar grafted polyethylene with higher grafting rate and lower gel content; the obtained polymer does not need to be dried and separated, the preparation process is short, and due to the advantages of the catalyst and the polymer preparation method, and the polymer has a higher bulk density.

[0109] The other conditions of Comparative Example 3 are consistent with those of Comparative Example 1, but the initiator is not in the catalyst but is added during the grafting reaction, so that the initiator cannot be uniformly introduced into the polymer during the first step of polymerization, resulting in low grafting efficiency (Table 2), which shows that the addition of the initiator to the catalyst and the uniform dispersion of the initiator in the polymer through the polymerization reaction achieve an unexpected technical effect.

[0110] It should be noted that the above-described examples are only used to explain the present application and do not constitute any limitation on the present application. The present application is described by referring to typical examples, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. The present application can be modified as specified within the scope of the claims of the present application, and the present application can be revised without departing from the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and examples, it does not mean that the present application is limited to the specific examples disclosed therein, on the contrary, the present application can be extended to all other methods and applications having the same function.

[0111] All publications, patent applications, patents and other references mentioned in this specification are hereby incorporated by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present specification will control.

[0112] When the present specification derives a material, substance, method, step, device or component, etc. with the word head "known to those skilled in the art", "prior art" or similar language, the object derived by the word head covers those commonly used in the art at the time of the present application, but also includes those not commonly used at present, but will be recognized as suitable for similar purposes in the art.

[0113] The endpoints of the ranges and any values disclosed in the specification are not limited to the precise values recited as the exact dimensions are not considered to be critical unless specifically indicated otherwise. The endpoints of the ranges of values are generally intended to be read to be open-ended, and the ranges of values are generally intended to be continuous along at least a portion of the value range unless otherwise indicated. For values which are less than one, multiple, e.g., 10, can be present, such that there can be 10 of the value. For values which are greater than one, multiple, e.g., 10, can be present, such that there can be 10 of the value. The upper and lower amount, dosage and other numerical values should be read and interpreted as being open-ended ranges unless the context clearly suggests otherwise. The use of broader terms in some instances and not in other situations can be related to the context. Terms such as "about" can encompass a range of values less than and greater than the stated value, as well as the stated value itself. The use of smaller terms such as "about a range" can indicate that the end points of the ranges are inclusive.

[0114] In the context of the present specification, unless specifically stated otherwise, any reference to any document, act, item, or thing is a reference to it as of the filing date of the present application, and any reference to an enabling prior publication or known concept is a reference to that publication or concept as of the filing date of the present application.

[0115] Moreover, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas are to be considered as part of the original disclosure or original description of the present application, and should not be considered as new content which has not been disclosed or anticipated herein, unless the person skilled in the art considers that the combination is obviously unreasonable.

Claims

1. A supported post-transition metal catalyst, comprising a blend of the following raw materials and / or reaction products: a support, a post-transition metal catalyst, an activator, and a radical initiator. The activator is an organoaluminum compound; The structure of the post-transition metal catalyst is as shown in formula (Ⅰ): In formula (Ⅰ), R1 to R2 are each selected from hydrogen or alkyl or aryl groups having 1 to 20 carbon atoms; R3 to R8 are each selected from hydrogen or alkyl or aryl groups having 1 to 20 carbon atoms; X1 and X2 are halogens; M is Ni.

2. The supported transition metal catalyst according to claim 1, characterized in that, The carrier is selected from inorganic oxide carriers; and / or, The particle size of the carrier is 0.01–5 μm.

3. The supported transition metal catalyst according to claim 1, characterized in that, The carrier is silicon oxide and / or aluminum oxide; and / or, The particle size of the carrier is 0.01–2 μm.

4. The supported transition metal catalyst according to claim 1, characterized in that, The carrier is silicon dioxide.

5. The supported transition metal catalyst according to claim 1, characterized in that, The free radical initiator is selected from at least one of azo initiators and peroxide initiators.

6. The supported transition metal catalyst according to claim 1, characterized in that, The free radical initiator is selected from at least one of benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, tert-butyl peroxide, diisobutyl percarbonate, azobisisobutyronitrile, and azobisisoheptanenitrile.

7. The supported transition metal catalyst according to claim 1, characterized in that, The organoaluminum compound is AlR n X (3-n) or contains Compounds with the structure R, where R is an alkyl group having 1 to 10 carbon atoms, X is a halogen, and n is an integer from 1 to 3.

8. The supported transition metal catalyst according to claim 1, characterized in that, The organoaluminum compound is selected from at least one of trimethylaluminum, triethylaluminum, methylaluminoxane, diethylaluminum chloride, diethylaluminum chloride, tri-n-butylaluminum, triisobutylaluminum, sesquimethylaluminum chloride, and sesquiethylaluminum chloride.

9. The supported transition metal catalyst according to claim 1, characterized in that, In formula (Ⅰ), R1 to R2 are each selected from at least one of hydrogen, alkyl with 1 to 10 carbon atoms, and aryl with 6 to 10 carbon atoms.

10. The supported transition metal catalyst according to claim 1, characterized in that, In formula (I), R3 to R8 are each selected from at least one of hydrogen, alkyl groups having 1 to 10 carbon atoms, and aryl groups having 6 to 10 carbon atoms.

11. The supported transition metal catalyst according to claim 1, characterized in that, In formula (Ⅰ), X1 and X2 are each selected from at least one of chlorine, bromine, and iodine.

12. The supported transition metal catalyst according to any one of claims 1-11, characterized in that, Based on a total mass of 100 wt% for the supported transition metal catalyst, the content of the post-transition metal element M in the supported transition metal catalyst is 0.1–5 wt%, and / or the content of the free radical initiator is 10–60 wt%; and / or, The molar ratio of aluminum to the post-transition metal M in the organoaluminum compound is (5-500):

1.

13. The supported transition metal catalyst according to any one of claims 1-11, characterized in that, Based on a total mass of 100 wt% for the supported transition metal catalyst, the content of the post-transition metal element M in the supported transition metal catalyst is 0.3–3 wt%, and / or the content of the free radical initiator is 20–40 wt%; and / or, The molar ratio of aluminum to the post-transition metal M in the organoaluminum compound is (20-200):

1.

14. The supported transition metal catalyst according to any one of claims 1 to 11, characterized in that, The average particle size of the supported transition metal catalyst is 7–100 μm; and / or, The particle size distribution of the supported transition metal catalyst is less than 2.

15. The supported transition metal catalyst according to any one of claims 1 to 11, characterized in that, The average particle size of the supported transition metal catalyst is 8–30 μm; and / or, The particle size distribution of the supported transition metal catalyst is less than 1.

5.

16. A method for preparing a supported transition metal catalyst according to any one of claims 1 to 15, comprising the following steps: (1) The components including the post-transition metal catalyst, activator, support, and free radical initiator are dispersed in an organic solvent to form a slurry; (2) The slurry obtained in step (1) is spray-dried to obtain the supported transition metal catalyst.

17. The preparation method according to claim 16, characterized in that, The preparation of the slurry in step (1) includes: dissolving the free radical initiator, the post-transition metal catalyst, and the activator in an organic solvent and then adding the carrier.

18. The preparation method according to claim 16, characterized in that, The preparation of the slurry in step (1) includes: first dissolving the free radical initiator, the subsequent transition metal catalyst, and the activator in an organic solvent, and then adding the carrier at 20-45°C and mixing for 2-12 hours.

19. The preparation method according to claim 16, characterized in that, The spray drying conditions in step (2) are: inlet temperature 50–200°C, outlet temperature 30–150°C; and / or, In step (2), the air inlet flow rate of the spray drying nozzle is 10-50 m³ / h. 3 / h.

20. The preparation method according to claim 16, characterized in that, The organic solvent is selected from at least one of alkanes, haloalkanes, aromatics, heterocyclic compounds, ethers, ketones, and esters; and / or, The amount of organic solvent used is 5 to 100 mL relative to 1 g of carrier.

21. The preparation method according to claim 16, characterized in that, The organic solvent is selected from at least one of pentane, hexane, heptane, dichloromethane, chloroform, benzene, toluene, chlorobenzene, chlorotoluene, tetrahydrofuran, acetone, diethyl ether, and ethyl acetate; and / or, The amount of organic solvent used is 10 to 50 mL relative to 1 g of carrier.

22. The preparation method according to any one of claims 16-21, characterized in that, Based on mass parts, relative to 1 part of the support, the amount of post-transition metal catalyst is 0.01-1 part, the amount of activator is 0.1-30 parts, and the amount of free radical initiator is 0.02-10 parts.

23. The preparation method according to any one of claims 16-21, characterized in that, By mass, relative to 1 part of the support, the amount of the post-transition metal catalyst is 0.05-0.5 parts, the amount of the activator is 0.3-10 parts, and the amount of the free radical initiator is 0.1-3 parts.

24. The use of a supported transition metal catalyst according to any one of claims 1 to 15 or a supported transition metal catalyst prepared by any one of claims 16 to 23 in olefin polymerization.

25. The application according to claim 24, characterized in that, The applications of the supported transition metal catalysts in olefin polymerization include: 1) Ethylene is contacted with the supported transition metal catalyst to carry out ethylene polymerization reaction, thereby obtaining polyethylene powder containing a free radical initiator; 2) Contact the polar monomer with the polyethylene powder containing the free radical initiator obtained in 1), so that the free radical initiator initiates the in-situ grafting of the polar monomer onto the polyethylene.

26. The application according to claim 25, characterized in that, The polar monomer is a compound containing a double bond and a polar group.

27. The application according to claim 26, characterized in that, The polar monomer is at least one of acrylic acid and its derivatives or esters, maleic anhydride or esters, maleate, alkenyl bisphenol A ether, acrylonitrile, styrene and its homologues, and glycidyl methacrylate.

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