CN114249851B - Low bulk density ultra-high molecular weight polyethylene micro-powder - Google Patents

Abstract

The invention provides a class of ultra-high molecular weight polyethylene microparticles, the particle size of which is smaller than conventional commercially available ultra-high molecular weight polyethylene, and the particle bulk density is small. Specifically, the invention provides microparticles with the following characteristics: (a ) The viscosity-average molecular weight is in the range of 1.5-8 million; (b) At least 85% of the weight ratio passes through a 100-mesh mesh sieve; the particle diameter (d50) is 80μm≤d50≤110μm; (c) The powder bulk density is 0.20- 0.30g/cm ³ ; (d) branched chain content of carbon atoms in the skeleton <1/100,000C. The ultra-high molecular weight polyethylene particles provided by the invention are suitable for producing microporous filter materials.

Description

A Class of Low Bulk Density Ultra High Molecular Weight Polyethylene Micropowder

technical field

The invention relates to a class of ultra-high molecular weight polyethylene particles suitable for manufacturing microporous filter materials. More specifically, it relates to a kind of unbranched polyethylene particles with a viscosity average molecular weight of 1.5-8 million g/mol, a particle size distribution centered at (d50) of 80 μm≤d50≤110 μm, and a bulk density of 0.20-0.30 g/ ^cm3 .

Background technique

Ultra-high molecular weight polyethylene (UHMWPE) is a kind of linear polyethylene product with a viscosity-average relative molecular weight of more than 1.5 million. It has high impact resistance, extremely high wear resistance, high corrosion resistance, self-lubrication, and environmental stress cracking resistance. Thermoplastic engineering plastics with the advantages of high strength, safety and sanitation can be processed to form various products such as plates, pipes, fibers, films, etc., and are mainly used in military such as bulletproof vests, bulletproof helmets, bulletproof armor, cut-resistant gloves, and aerospace and navigation equipment. , rail transit, medical stents, fine filtration and lithium battery diaphragms and other high-end fields.

In recent years, the development of polymer particles has also made some progress. Various types of polymer special materials are widely used in different production fields. The materials involve acrylic series resins, styrene resins, melamine resins and poly Olefin resins, especially ultra-high molecular weight polyethylene resin particles, are more considered to be used in various new materials and new applications due to their excellent properties. It has become a new trend to use them to prepare microporous materials for filtration and separation processes. New application direction of ultra-high molecular weight polyethylene. UHMWPE microporous filter material refers to a material that uses UHMWPE as an organic matrix. During the molding process, a large number of microscopic interconnected pores in the thickness direction are produced on the matrix, so that it can meet the needs of various processing processes. At present, the methods for preparing UHMWPE microporous materials mainly include sintering. Method, particle filling method, nuclear track method, melt extrusion stretching method, TIPS method, TIPS-S method, etc. Different molding methods often have a great influence on important parameters such as pore size, distribution and porosity of microporous materials. It will also have a direct effect on its microstructure; on the other hand, the particle size of UHMWPE particles also has a significant impact on the performance of microporous filter products. When the sintering process is used to prepare microporous filter materials, heat gradually enters from the surface of the powder particles. In the inside of the particle, the larger the particle, the longer the time from the softening of the particle surface to the melting inside the particle, and the easier it is to form a porous structure resulting in a large opening rate, but the microporous structure tends to become irregular and the distribution of micropores also changes. If the particle size is not uniform, the strength will decrease; the finer the particles, the shorter the melting time, the easier to stick, the more difficult it is to form a porous structure, the finer and more uniform the microporous structure, the lower the porosity, but the higher the strength; At the same time, the size of the particle size and the shape of the particles almost determine the pore size of the prepared product. According to the pore-forming mechanism of the sintering method, the particles of UHMWPE are piled up with each other, and the gap between the particles constitutes the source of the pores. The larger the UHMWPE particle size, the more irregular the particle shape, the larger the gap between the particles, and the larger the pore size of the product.

At present, there is still little progress in the development of differentiated and dedicated ultra-high molecular weight polyethylene resin particles for microporous filter materials, and general-purpose materials with high bulk density (0.40-0.50g/cm ³ ) still dominate the market , The polymer particle resin particle size range (D50) is mainly concentrated between 120 microns and 200 microns, or coarse particles above 600 microns. In addition, Mitsui Chemicals also produces a UHMWPE powder with a very fine particle size. The registered trademark is MIPELONTM ^. Patent CN200580039390.2 discloses ethylene-based polymer microparticles and a catalyst for their manufacture. At least 95% of the weight ratio of the polymer microparticles passes through a 37-micron mesh sieve, and the median diameter (d50) measured by the laser diffraction scattering method is 3 μm≤ d50≤25μm, the bulk density of the particles prepared by this technology is not listed, and the polymer requires cumbersome steps to remove inorganic impurities, and the preparation process of the catalyst reported by the patent method must use regulated toluene as a solvent . The patented technologies (202010585230.4, 202010585258.8, 202010583913.6) we developed in the early stage can obtain ultra-high and ultra-high molecular weight polyethylene resin particles with a particle size (d50) of 40μm≤d50≤80μm, and the bulk density of the particles prepared by this technology≥ 0.35g/cm ³ .

To sum up, there is still a lack of a special resin powder for ultra-high molecular weight polyethylene with low bulk density and fine particle size, which is suitable for manufacturing microporous filter materials.

Contents of the invention

The present invention provides a class that can be applicable to the manufacture of microporous filter materials, without branching, with a viscosity-average molecular weight of 1.5-8 million g/mol, an average particle size range slightly smaller than that of the general commercially available type, and a particle size distribution concentrated in (d50 ) is 80μm≤d50≤110μm, and the bulk density is 0.20-0.30g/cm ³ ultra-high molecular weight polyethylene particles.

The first aspect of the present invention provides a kind of ultra-high molecular weight polyethylene microparticles, the microparticles have the following characteristics:

(a) the viscosity-average molecular weight is 1.5-8 million g/mol;

(b) ≥85 wt% can pass through a 100-mesh mesh sieve, and the median particle diameter (d50) is 80 μm≤d50≤110 μm.

In another preferred example, the viscosity-average molecular weight of the microparticles is 1.5-4 million g/mol.

In another preferred example, the d50 of the particles is 90 μm≤d50≤100 μm.

In another preferred example, the powder bulk density of the particles is 0.20-0.30 g/cm ³ .

In another preferred embodiment, the bulk density of the particles is 0.22-0.28 g/cm ³ ; more preferably 0.22-0.26 g/cm ³ .

In another preferred example, in the microparticles, the number of alkane branched chains on the polymer chain is <1/100,000C (ie, the number of alkane branched chains in 100,000 carbon atoms is <1).

The second aspect of the present invention provides a method for preparing polyethylene microparticles as described in the first aspect of the present invention. The method includes the steps of: contacting ethylene with a catalyst and a cocatalyst to carry out a catalytic polymerization reaction, thereby obtaining the ultra-high molecular weight polyethylene particles;

Wherein, the catalyst is a catalyst particle, or a catalyst slurry comprising the catalyst particle; the silicon content of the catalyst is 20-40 parts by weight, the magnesium content is 10-30 parts by weight, and the aluminum content is 2-4 parts by weight. parts, the titanium content is 3-5 parts by weight, and the chlorine content is 20-60 parts by weight.

In another preferred embodiment, the solid concentration of catalyst particles in the catalyst feed liquid is 200-250 g/L.

In another preference, the method includes the steps of:

(1) In an inert solvent, feed ethylene gas into the reaction kettle with the catalyst and cocatalyst added in advance, so that the pressure in the kettle reaches 0.2-1.5MPa, carry out the polymerization reaction at 40-80°C for 1-3h, and then stop the ventilation into ethylene;

(2) Make the temperature in the kettle drop below 50°C;

(3) removing the solvent from the slurry obtained in step (2);

(4) Obtain the polyethylene microparticles as described in claim 1 after negative pressure drying.

In another preferred example, additional steam stripping is required between the step (3) and the step (4), that is, the wet material obtained in the step (3) is stripped to deeply remove the organic solvent contained in the powder .

In another preference, the catalyst is prepared by the following method:

(a) contact with C1-C10 alcohol with magnesium source and react at 60-120°C, then add nano-silica gel, cool down to below -30°C to obtain precursor slurry P-I;

(b) using the precursor slurry P-I obtained in step (a) to contact with an aluminum alkyl at a temperature lower than -30°C, and then raising the temperature to 60-120°C for 2-6h to obtain the precursor slurry P-II;

(c) Use the precursor slurry P-II obtained in step (b) to cool down to below -30°C, contact with the inert hydrocarbon solution of titanium compound for 0.5-3h, then raise the temperature to 60-120°C and keep it for 2-6h to obtain the catalyst Serum C-III;

(d) Filtrating the catalyst slurry C-III obtained in step (c) to obtain a catalyst.

In another preferred example, the magnesium source is magnesium chloride, preferably anhydrous magnesium chloride.

In another preferred example, the method includes:

(a) under inert gas protection conditions, anhydrous magnesium chloride is added to the mixed solution of inert hydrocarbon solvent and ≥2 equivalents of magnesium chloride's C1-C10 alcohols (preferably 2-6 equivalents of C1-C10 alcohols) for contacting, React at 60-120°C to form a homogeneous solution, add nano-silica gel to prepare a composite carrier, and then lower the temperature to below -30°C to obtain the precursor slurry P-I; the cooling rate is preferably 1-10°C/min; more preferably 1- 5°C/min, most preferably 1°C/min; in the above reaction, the amount of anhydrous magnesium chloride is used as 1 equivalent;

(b) The precursor slurry P-I obtained in step (a) is contacted with alkylaluminum for at least 1 h at a temperature lower than -30 ° C, and then heated to 60-120 ° C for 2-6 h to obtain the precursor slurry P-II; wherein The heating rate is preferably 1-10°C/min;

(c) Cool the precursor slurry P-II obtained in step (b) to below -30°C, contact with the inert hydrocarbon solution of titanium compound for 0.5-3h, then raise the temperature to 60-120°C and keep it for 2-6h to obtain the catalyst Slurry C-III; wherein the cooling rate is preferably 1-10°C/min, and the heating rate is preferably 1-10°C/min;

(d) Filtrating the catalyst slurry C-III obtained in step (c) to obtain a catalyst.

In another preferred example, the mass ratio of nano-silica gel to magnesium chloride is 1-3:1.

In another preferred example, the appearance of the nano-silica gel is white powder, the bulk density is <0.15g/cm ³ , and the particle size range can be 15-100nm, preferably 30-50nm.

In another preferred example, the catalyst preparation method further includes the step: (e) drying the catalyst obtained in step (d) to obtain catalyst powder.

In another preferred example, in the preparation of the catalyst, the C1-C10 alcohol described in step (a) is selected from the group consisting of methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, 2-Ethylhexanol, n-octanol, or combinations thereof.

In another preference, in the preparation of the catalyst, the aluminum alkyl in step (b) is selected from the group consisting of ethyl aluminum dichloride, aluminum diethyl chloride, aluminum triethyl, triisobutyl Aluminum, ethylaluminum sesquichloride, or butylaluminum sesquichloride.

In another preferred example, in the catalyst preparation, the molar ratio of titanium compound to magnesium chloride in step (c) may be 0.3-0.8:1, preferably 0.4-0.6:1, most preferably 0.5:1.

In another preferred example, no toluene, halogenated hydrocarbons or aromatic hydrocarbons are used in the catalyst preparation step.

In another preferred example, the titanium compound is selected from the following group: TiCl ₄ , TiR ₄ , or alkyl complexes shown in structural formula I-IV; wherein R is C1-C6 alkyl, allyl, Benzyl, NMe ₂ , the alkyl is preferably methyl, ethyl, propyl or butyl.

Wherein, X is SR ⁵ or P(R ⁵ ) ₂ ;

R ¹ , R ² , R ³ , R ⁴ , and R ⁵ are independently substituted or unsubstituted groups selected from the group consisting of C1-C6 alkyl, C2-C6 alkenyl, C3-C8 cycloalkyl, C6-C10 aryl, halogenated C3-C8 cycloalkyl, 5-7 membered heteroaryl;

Or R ³ and R ⁴ , and the carbon atoms connected to them together form a 5-7 membered saturated, partially unsaturated or aromatic carbocyclic or heterocyclic ring;

R ⁶ is selected from the following group: C1-C6 alkyl, NH ₂ , N(C1-C6 alkyl) ₂ , allyl, benzyl, C1-C6 silyl; the alkyl is preferably methyl , ethyl, propyl or butyl;

R ^is selected from the group consisting of C1-C6 alkyl, C2-C6 alkenyl or C3-C8 cycloalkyl;

Wherein, the skeleton of the heteroaryl group has 1-3 heteroatoms selected from the group consisting of N, S(O), P or O;

Unless otherwise specified, the "substitution" refers to being substituted by one or more (such as 2, 3, 4, etc.) substituents selected from the following group: halogen, C1-C6 alkyl, halogenated C1-C6 alkyl, C1-C6 alkoxy, halogenated C1-C6 alkoxy.

In another preferred embodiment, the titanium complex is a molecule with the following structure:

The third aspect of the present invention provides a microporous filtration product, which is prepared by using the ultra-high molecular weight polyethylene particles as described in the first aspect of the present invention.

In another preferred example, the porosity of the microporous filter product is ≥ 40%.

In another preferred example, the filtration precision of the microporous filter product can be at least equal to 0.45 microns.

In another preferred example, the solid insoluble matter filtration efficiency of the microporous filtration product is greater than 99.8%.

In another preferred example, under the condition of 0.2MPa water pressure, the water penetration of the microporous filter product can reach 20m ³ /h.

A fourth aspect of the present invention provides a method for preparing a product as described in the third aspect of the present invention, said method comprising the steps of:

(i) using polyethylene wax and calcium stearate as composite additives, mixed with the ultra-high molecular weight polyethylene microparticles described in the first aspect of the present invention, to obtain a mixed material;

(ii) carrying out pressureless sintering with described packing mold;

(iii) cooling down to obtain an ultra-high molecular weight polyethylene microporous filter product.

In another preferred example, the mass ratio of ultra-high molecular weight polyethylene particles: polyethylene wax: calcium stearate is 250-350:2-8:0.8-1.2.

In another preferred example, the sintering temperature is 180-220°C.

In another preferred example, the sintering time is 10-20 minutes.

In another preferred example, the temperature reduction is water cooling.

It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described in the following (such as embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, we will not repeat them here.

Description of drawings

Fig. 1 is representative polymer (embodiment 3) particle size distribution report;

Fig. 2 and Fig. 3 are representative polymkeric substance (embodiment 3) SEM electron microscope pictures;

Fig. 4 is a picture of ultra-high molecular weight polyethylene sintered microporous filter tube.

Detailed ways

After long-term and in-depth research, the present inventors have prepared a kind of ultra-high molecular weight polyethylene particles suitable for manufacturing microporous filter materials, and the prepared polyethylene chains are unbranched and have a viscosity-average molecular weight of 1.5-8 million g/m. At least 85% of the mole and weight ratio pass through a 100-mesh mesh sieve, the particle size distribution (d50) is 80μm≤d50≤110μm, and the bulk density is 0.20-0.30g/cm ³ polyethylene particles. Based on the above findings, the inventors have accomplished the present invention.

Unbranched, low bulk density ultra-high molecular weight polyethylene particles and its preparation

The invention provides a class of ultra-high molecular weight polyethylene microparticles. The microparticles at least meet the following characteristics: (a) the viscosity-average molecular weight is in the range of 1.5 million to 8 million; (b) the weight ratio is at least 85% through a 100-mesh mesh sieve ; The median particle diameter (d50) is 80 μm≤d50≤110 μm; (c) The powder bulk density is 0.20-0.30 g/cm ³ .

In addition, the molecular structure of the polymer can also satisfy (d) the number of alkane branched chains on the polymer chain <1/100,000C (measured by melting 13C NMR).

The molecular weight of the ultra-high molecular weight polyethylene microparticles described in the present invention can be conveniently controlled by the polymerization conditions, that is, in the presence of a catalyst and a cocatalyst, catalyzing ethylene polymerization at 40-80°C and 0.2-2.0MPa ethylene pressure to obtain The above-mentioned ultra-high molecular weight polyethylene powder. In a preferred embodiment of the present application, at least 85% by weight of the polyethylene particles pass through a 100-mesh mesh sieve, and 80 μm≤d50≤110 μm.

The preparation method of ultra-high molecular weight polyethylene microparticles of the present invention is as follows:

The heterogeneous catalytic system composed of the main catalyst and the alkyl aluminum compound as the cocatalyst is contacted with ethylene and reacted for 1-18 hours at the ethylene partial pressure of 0.2 to 2.0 Mpa and the range of 0 to 100°C. The molar ratio of catalyst and cocatalyst is 1:1-5000, generally can polymerize 2-6 hours when 1:10-2000 so that catalytic activity, polymer property and production cost are all maintained in a better range, preferably 1: 20 to 500.

Polymerization is generally carried out in inert organic solvents, such as hydrocarbons, cyclic hydrocarbons or aromatic hydrocarbons, and can also be carried out in halogenated solvents, such as dichloroethane and chlorobenzene. In order to facilitate the operation of the reactor, inert organic solvents can be used Hydrocarbons with less than 12 carbons. For example, but not limited to, propane, isobutane, n-pentane, 2-methylbutane, n-hexane, cyclohexane, toluene, chlorobenzene, dichloroethane, and mixtures thereof.

The polymerization temperature is maintained at 0 to 100°C, and can be maintained at 40 to 80°C to achieve good catalytic activity and productivity.

Better reactor operating parameters and polymers can be obtained by operating within the partial pressure of polymerized ethylene within the range of 0.2 to 1.5 Mpa.

The cocatalyst is an alkylaluminum compound, an alkylaluminoxane or a weakly coordinated anion; the alkylaluminum compound is preferably AlEt ₃ , AlMe ₃ or Al(i-Bu) ₃ , AlEt ₂ Cl, an alkylaluminum oxide Alkanes are preferably methylalumoxane, MMAO (modified methylalumoxane), etc.; weakly coordinating anions are preferably [B(3,5-(CF ₃ ) ₂ C ₆ H ₃ ) ₄ ]-, -OSO ₂ CF ₃ or ((3,5-(CF ₃ ) ₂ )C ₆ H ₃ ) ₄ B-. Catalyst and cocatalyst can be added in any order to make the polymerization proceed, preferably AlEt ₃ . The ratio of the catalyst and co-catalyst used in the polymerization is variable, usually the polymerization time is 1-18 hours, the molar ratio of the catalyst and the co-catalyst is 1:1-5000, generally it can be polymerized at 1:10-2000 -6 hours in order to keep catalytic activity, polymer properties and production costs in a good range, preferably 1:20-500.

In a preferred embodiment of the present invention, the catalyst catalyzes ethylene polymerization at 40-80°C and 0.2-0.8 MPa ethylene pressure to obtain ultra-high molecular weight polyethylene particles, and the weight ratio of the powder obtained by polymerization is at least 85% and passes through 100 The target mesh sieve has a median diameter (d50) measured by the laser diffraction scattering method of 80 μm≤d50≤110 μm, more preferably 90 μm≤d50≤100 μm, and a polyethylene viscosity-average molecular weight of 1.5-8 million; more preferably, poly The viscosity-average molecular weight of ethylene is 2-4 million.

The branched structure can be analyzed by melting ¹³ C NMR. Analysis results confirm that the ultra-high molecular weight polyethylene provided by the present invention has less than one branched chain per 100,000 skeleton carbon atoms in the polymer.

The ultra-high molecular weight polyethylene particles created by the invention have a powder bulk density of 0.20-0.30g/cm ³ , more preferably 0.22-0.28g/cm ³ , and can be used to prepare microporous filter materials.

Polyethylene catalyst and its preparation

The non-branched and low bulk density ultra-high molecular weight polyethylene microparticles of the invention are prepared through a titanium series catalyst containing nano silica gel and magnesium chloride composite support.

Wherein, the catalyst is a catalyst particle, or a catalyst slurry comprising the catalyst particle; the silicon content of the catalyst is 20-40 parts by weight, the magnesium content is 10-30 parts by weight, and the aluminum content is 2-4 parts by weight. parts, the titanium content is 3-5 parts by weight, and the chlorine content is 20-60 parts by weight.

In another preferred embodiment, the concentration of catalyst particles in the catalyst feed liquid is 200-250 g/L.

In another preference, the catalyst is prepared by the following method:

(a) under inert gas protection conditions, anhydrous magnesium chloride is added to the mixed solution of inert hydrocarbon solvent and ≥2 equivalents of magnesium chloride's C1-C10 alcohols (preferably 2-6 equivalents of C1-C10 alcohols) for contacting, React at 60-120°C to form a homogeneous solution, add 1-3 equivalents of nano-silica gel for loading to prepare a composite carrier, and then lower the temperature to below -30°C to obtain the precursor slurry P-I; the cooling rate is preferably 1-10 °C/min; more preferably 1-5 °C/min, most preferably 1 °C/min; in the above reaction, the amount of anhydrous magnesium chloride is taken as 1 equivalent;

(b) The precursor slurry P-I obtained in step (a) is contacted with alkylaluminum for at least 1 h at a temperature lower than -30 ° C, and then heated to 60-120 ° C for 2-6 h to obtain the precursor slurry P-II; wherein The heating rate is preferably 1-10°C/min;

(c) Cool the precursor slurry P-II obtained in step (b) to below -30°C, contact with the inert hydrocarbon solution of titanium compound for 0.5-3h, then raise the temperature to 60-120°C and keep it for 2-6h to obtain the catalyst Slurry C-III; wherein the cooling rate is preferably 1-10°C/min, and the heating rate is preferably 1-10°C/min;

(d) Filtrating the catalyst slurry C-III obtained in step (c) to obtain a catalyst.

In another preferred example, the catalyst preparation method further includes the step: (e) drying the catalyst obtained in step (d) to obtain catalyst powder.

In another preference, in the preparation of the catalyst, the C1-C10 alcohol described in step (a) is preferably methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, 2-ethyl Hexanol or n-octanol.

In another preference, in the preparation of the catalyst, the mass ratio of the nano silica gel and magnesium chloride described in step (a) can be selected as 1-3:1, preferably 2-3:1, most preferably 3:1, The appearance of the nano-silica gel is amorphous white powder, the microstructure is flocculent and net-like quasi-granular structure, the bulk density is <0.15g/cm ³ , and the particle size range can be 15-100nm, preferably 30-50nm.

In another preference, in the preparation of the catalyst, the aluminum alkyl in step (b) is selected from the group consisting of ethyl aluminum dichloride, aluminum diethyl chloride, aluminum triethyl, triisobutyl Aluminum, ethylaluminum sesquichloride or butylaluminum sesquichloride.

In another preferred example, in the catalyst preparation, the molar ratio of titanium compound to magnesium chloride in step (c) may be 0.3-0.8:1, preferably 0.4-0.6:1, most preferably 0.5:1.

In another preferred example, no toluene, halogenated hydrocarbons or aromatic hydrocarbons are used in the catalyst preparation step.

In another preferred example, the titanium compound is TiCl ₄ or TiR ₄ , or an alkyl complex shown in structural formula I-IV; wherein R is C1-C6 alkyl, allyl, benzyl, NMe _2. The alkyl group is preferably methyl, ethyl, propyl or butyl.

Wherein, X is SR ⁵ or P(R ⁵ ) ₂ ;

R ¹ , R ² , R ³ , R ⁴ , and R ⁵ are independently substituted or unsubstituted groups selected from the group consisting of C1-C6 alkyl, C2-C6 alkenyl, C3-C8 cycloalkyl, C6-C10 aryl, halogenated C3-C8 cycloalkyl, 5-7 membered heteroaryl;

Or R ³ and R ⁴ , and the carbon atoms connected to them together form a 5-7 membered saturated, partially unsaturated or aromatic carbocyclic or heterocyclic ring;

R ⁶ is selected from the following group: C1-C6 alkyl, NH ₂ , N(C1-C6 alkyl) ₂ , allyl, benzyl, C1-C6 silyl; the alkyl is preferably methyl , ethyl, propyl or butyl;

R ^is selected from the group consisting of C1-C6 alkyl, C2-C6 alkenyl or C3-C8 cycloalkyl;

Wherein, the skeleton of the heteroaryl group has 1-3 heteroatoms selected from the group consisting of N, S(O), P or O.

Unless otherwise specified, the "substitution" refers to being substituted by one or more (such as 2, 3, 4, etc.) substituents selected from the following group: halogen, C1-C6 alkyl, halogenated C1-C6 alkyl, C1-C6 alkoxy, halogenated C1-C6 alkoxy.

In another preferred embodiment, the titanium complex is a molecule with the following structure:

UHMWPE Microporous Filtration Products

The ultra-high molecular weight polyethylene microparticles with no branching, irregular appearance and low bulk density can be used to prepare microporous filter materials. The present invention adopts polyethylene wax and calcium stearate as composite additives, and mixes them with the ultra-high molecular weight polyethylene microparticles according to a certain ratio for processing, and the mass composition of ultra-high molecular weight polyethylene microparticles: polyethylene wax: calcium stearate The ratio is 300:5:1, mix evenly, put it into the mold and carry out pressureless sintering on the molding machine, the sintering temperature is 180-220°C, the sintering time is 10-20min, and finally pass water to cool down to obtain ultra-high molecular weight polyethylene micropores Filtration products.

The porosity of the ultra-high molecular weight polyethylene microporous filter product reaches 40-60%, the micropores are evenly distributed, the minimum filtration precision can be equal to 0.45 microns, the filtration efficiency of solid insolubles is greater than 99.8%, and the permeability is excellent. Under the condition of water pressure, the water penetration can reach 20m ³ /h.

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. For the experimental methods without specific conditions indicated in the following examples, the conventional conditions or the conditions suggested by the manufacturer are usually followed. Percentages and parts are by weight unless otherwise indicated.

The following examples show different aspects of the present invention. The examples given include polyethylene microparticles, polymerization process for making polyethylene microparticles, microfiltration article process and their properties.

The particle size distribution of polyethylene microparticles was measured by a Malvern S-type particle size analyzer, using n-hexane or ethanol as a dispersant.

The viscosity-average molecular weight of polyethylene particles is measured by a high-temperature viscometer. Generally, 2.5-2.8 mg of a sample is weighed and dissolved in 15 mL of decahydronaphthalene. The calculation formula is as follows:

ηsp=t-t0/t0

ηr=t/t0

c＝100*m(g)*ρ135℃/V(ml)*ρ25℃

η1=(ηsp+5Inηr)/6c

η2＝【2(ηsp-ηr)】0.5/c

【η】＝(η1+η2)/2

Mv＝4.55×104×【η】1.37

The measurement of polyethylene branched chain content is obtained by melting 13C-NMR spectrum (reference: JOURNAL OFPOLYMER SCIENCE: Polymeo Physics Edition VOL.11,275-287, 1973). On the magic angle rotating attachment, it is measured at 140°C, and the measurement accumulation time of each sample is more than 16 hours to meet the measurement accuracy of more than 1 branched chain/100000 carbons.

Example 1

Under dry nitrogen conditions, add 15L hexane and 1.5L n-butanol into a 30L stainless steel reactor, mix well, then add 350g magnesium chloride, then heat the oil bath to 85°C, control the stirring speed to 100rpm, and react for 2 hours until a clear and uniform solution ; Add 1050g of nano silica gel for loading to prepare a composite carrier, stir and load for 2 hours, start to set the cooling rate at 1°C/min and cool down to below -30°C, and precipitate a solid to obtain a catalyst precursor slurry; lower the temperature of the catalyst precursor slurry to - Below 30°C, slowly add 1L diethylaluminum chloride dropwise to react for 2 hours, then control the temperature rise rate to 1°C/min, raise the temperature to 85°C for 4 hours; lower the temperature to below -30°C again, add dropwise 653g of the fourth subgroup The 5 L hexane solution of metal titanium alkyl complex 3 was subjected to the complexation reaction for 1 h, and then the heating rate was controlled at 1 °C/min, and the temperature was raised to 85 °C for 4 h. After the reaction time was over, sedimentation and filtration were carried out. The filter cake was made into slurry to obtain 10L slurry type ultra-high activity catalyst CAT-1, and 100mL of the slurry catalyst was dried to obtain a solid catalyst mass of 21.1g, so the concentration of the slurry catalyst was calibrated to be 211g/L, and the titanium content was measured The silicon content is 38.0 wt%, the magnesium content is 12.0 wt%, the aluminum content is 3.3 wt%, and the chlorine content is 33.2 wt%.

Example 2

Under dry nitrogen conditions, add 15L hexane and 1.5L n-butanol into a 30L stainless steel reactor, mix well, then add 350g magnesium chloride, then heat the oil bath to 85°C, control the stirring speed to 100rpm, and react for 2 hours until a clear and uniform solution ; Add 1050g of nano silica gel for loading to prepare a composite carrier, stir and load for 2 hours, start to set the cooling rate at 1°C/min and cool down to below -30°C, and precipitate a solid to obtain a catalyst precursor slurry; lower the temperature of the catalyst precursor slurry to - Below 30°C, slowly add 1L diethylaluminum chloride to contact for 2 hours, then control the temperature rise rate to 1°C/min, raise the temperature to 85°C and react for 4 hours; lower the temperature to below -30°C again, add dropwise 1361g of the fourth subgroup The 5 L hexane solution of metal titanium alkyl complex 5 was subjected to the complexation reaction for 1 hour, and then the heating rate was controlled to be 1°C/min, and the temperature was raised to 85°C for 4 hours. The filter cake is made into slurry to obtain 10L slurry type ultra-high activity catalyst CAT-2, take 100mL of the slurry catalyst and dry to obtain a solid catalyst quality of 23.2g, so the concentration of the slurry catalyst is calibrated to be 232g/L, and the titanium content is measured The silicon content is 36.0wt%, the magnesium content is 11.6wt%, the aluminum content is 2.8wt%, and the chlorine content is 34.9wt%.

Example 3

Under the condition of dry nitrogen, add 15L hexane and 1.5L n-butanol into a 30L stainless steel reaction kettle, mix well, then add 350g magnesium chloride, then heat the oil bath to 85°C, control the stirring speed to 100rpm, and react for 2h until a clear and uniform solution ; Add 1050g of nano silica gel for loading to prepare a composite carrier, stir and load for 2 hours, start to set the cooling rate at 1°C/min and cool down to below -30°C, and precipitate a solid to obtain a catalyst precursor slurry; lower the temperature of the catalyst precursor slurry to - Below 30°C, slowly add 1L diethylaluminum chloride to contact for 2 hours, then control the temperature rise rate to 1°C/min, raise the temperature to 85°C for 4 hours; cool down to -30°C again, dropwise add 1358g of the fourth subgroup The 5 L hexane solution of metal titanium alkyl complex 7 was subjected to the complexation reaction for 1 h, and then the heating rate was controlled to be 1 °C/min, and the temperature was raised to 85 °C for 4 h. After the reaction time was over, sedimentation and filtration were carried out. 10L of slurry type ultra-high activity catalyst CAT-3 is obtained, 100mL of the slurry catalyst is taken and dried to obtain a solid catalyst mass of 22.6g, so the calibration concentration of the slurry catalyst is 226g/L, and the measured titanium content is 4.5wt %, the silicon content is 36.6wt%, the magnesium content is 11.9wt%, the aluminum content is 3.4wt%, and the chlorine content is 36.1wt%.

Example 4

Under dry nitrogen conditions, add 15L hexane and 1.5L n-butanol into a 30L stainless steel reactor, mix well, then add 350g magnesium chloride, then heat the oil bath to 85°C, control the stirring speed to 100rpm, and react for 2 hours until a clear and uniform solution ; Add 1050g of nano silica gel for loading to prepare a composite carrier, stir and load for 2 hours, start to set the cooling rate at 1°C/min and cool down to below -30°C, and precipitate a solid to obtain a catalyst precursor slurry; lower the temperature of the catalyst precursor slurry to - Below 30°C, slowly add 1L diethylaluminum chloride to contact for 2 hours, then control the temperature rise rate to 1°C/min, raise the temperature to 85°C for 4 hours; cool down to -30°C again, drop 1000g titanium tetrachloride 5L of hexane solution for complexation reaction for 1 hour, then control the temperature rise rate to 1°C/min, raise the temperature to 85°C for 4 hours, after the reaction time is over, settle and filter, and add hexane to the obtained filter cake to form a slurry to obtain 10L Slurry type ultra-high activity catalyst CAT-4, take 100mL of the slurry catalyst and dry to obtain a solid catalyst mass of 20.6g, so the calibration concentration of the slurry catalyst is 206g/L, and the measured titanium content is 3.0wt%, and the silicon content is 39.6wt%. , the magnesium content is 13.0wt%, the aluminum content is 3.7wt%, and the chlorine content is 34.8wt%.

Example 5

Under dry nitrogen conditions, add 15L hexane and 1.5L n-butanol into a 30L stainless steel reactor, mix well, then add 350g magnesium chloride, then heat the oil bath to 85°C, control the stirring speed to 100rpm, and react for 2 hours until a clear and uniform solution ; Add 1050g of nano silica gel for loading to prepare a composite carrier, stir and load for 2 hours, start to set the cooling rate at 1°C/min and cool down to below -30°C, and precipitate a solid to obtain a catalyst precursor slurry; lower the temperature of the catalyst precursor slurry to - Below 30°C, slowly add 1L of diethylaluminum chloride dropwise for 2 hours, then control the temperature rise rate to 1°C/min, raise the temperature to 85°C for 4 hours; cool down to below -30°C again, drop 5L of 760g TiBn ₄ The hexane solution was subjected to the complexation reaction for 1 hour, and then the heating rate was controlled at 1°C/min, and the temperature was raised to 85°C for 4 hours. After the reaction time was over, it was settled and filtered, and the obtained filter cake was added with hexane to make a slurry, and a 10L slurry type Ultra-high activity catalyst CAT-5, take 100mL of the slurry catalyst and dry to obtain a solid catalyst mass of 21.1g, so the calibration concentration of the slurry catalyst is 211g/L, and the measured titanium content is 3.2wt%, silicon content is 38.3wt%, magnesium The content is 12.3wt%, the aluminum content is 3.8wt%, and the chlorine content is 35.2wt%.

Example 6

Replace the 30L stainless steel stirred polymerization kettle with N ₂ successively, add AlEt ₃ (10mL) into the kettle with 8kg hexane under 0.4MPa nitrogen, control the stirring speed at 250rpm, preheat the temperature in the kettle to about 60°C, and then use 0.4MPa Under the condition of nitrogen pressure, use 2kg hexane to flush 30mg CAT-1 into the polymerization kettle, activate for 10min, then remove the nitrogen pressure in the kettle, and then feed ethylene gas to make the pressure in the kettle reach 0.2MPa, and control the temperature in the kettle to 70 ℃, stop feeding ethylene after 2 hours of polymerization, use a circulating constant temperature oil bath to lower the temperature in the kettle to below 50 ℃, vent the gas in the system and discharge the material, and obtain 1.26kg of granular polymer after drying, with a viscosity-average molecular weight of 2.3 million , the sieving rate of 100-mesh mesh sieve is 88% by weight, d ₅₀ = 84μm, the bulk density of powder is 0.21g/cm ³ , using melting ¹³ C-NMR spectrum in Agilent DD2 600MHz solid system with high temperature wide cavity magic angle Rotary attachments yield polyethylene branched content <1/100,000C.

Example 7

Replace the 30L stainless steel stirred polymerization kettle with N ₂ successively, add AlEt ₃ (10mL) into the kettle with 8kg hexane under 0.4MPa nitrogen, control the stirring speed at 250rpm, preheat the temperature in the kettle to about 60°C, and then use 0.4MPa Under the condition of nitrogen pressure, use 2kg hexane to flush 30mg CAT-1 into the polymerization kettle, activate for 10min, then remove the nitrogen pressure in the kettle, and then feed ethylene gas to make the pressure in the kettle reach 0.4MPa, and control the temperature in the kettle to 70 ℃, stop feeding ethylene after 2 hours of polymerization, use a circulating constant temperature oil bath to lower the temperature in the kettle to below 50 ℃, vent the gas in the system and discharge the material, and obtain 2.37kg of granular polymer after drying, with a viscosity-average molecular weight of 2.43 million , the sieving rate of 100-mesh mesh sieve is 89% by weight, d ₅₀ = 86μm, the bulk density of powder is 0.22g/cm ³ , using melting ¹³ C-NMR spectrum in Agilent DD2 600MHz solid system with high temperature wide cavity magic angle Rotary attachments yield polyethylene branched content <1/100,000C.

Example 8

Replace the 30L stainless steel stirred polymerization kettle with N ₂ successively, add AlEt ₃ (10mL) into the kettle with 8kg hexane under 0.4MPa nitrogen, control the stirring speed at 250rpm, preheat the temperature in the kettle to about 60°C, and then use 0.4MPa Under the condition of nitrogen pressure, use 2kg hexane to flush 30mg CAT-1 into the polymerization kettle, activate for 10min, then remove the nitrogen pressure in the kettle, and then feed ethylene gas to make the pressure in the kettle reach 0.6MPa, and control the temperature in the kettle to 70 ℃, stop feeding ethylene after 2 hours of polymerization, use a circulating constant temperature oil bath to lower the temperature in the kettle to below 50 ℃, vent the gas in the system and discharge the material, and obtain 3.26kg of granular polymer after drying, with a viscosity-average molecular weight of 3.28 million , the sieving rate of 100-mesh mesh sieve is 86% by weight, d ₅₀ = 101μm, the bulk density of powder is 0.26g/cm ³ , and the melting ¹³ C-NMR spectrum is used in Agilent DD2 600MHz solid system with high temperature and wide cavity magic angle Rotary attachments yield polyethylene branched content <1/100,000C.

Example 9

Replace the 30L stainless steel stirred polymerization kettle with N ₂ successively, add AlEt ₃ (10mL) into the kettle with 8kg hexane under 0.4MPa nitrogen, control the stirring speed at 250rpm, preheat the temperature in the kettle to about 60°C, and then use 0.4MPa Under the condition of nitrogen pressure, use 2kg hexane to flush 30mg CAT-1 into the polymerization kettle, activate for 10min, then remove the nitrogen pressure in the kettle, and then feed ethylene gas to make the pressure in the kettle reach 0.8MPa, and control the temperature in the kettle to 70 ℃, stop feeding ethylene after 2 hours of polymerization, use a circulating constant temperature oil bath to lower the temperature in the kettle to below 50 ℃, vent the gas in the system and discharge the material, and obtain 4.06kg of granular polymer after drying, with a viscosity-average molecular weight of 4.5 million , the sieving rate of 100-mesh mesh sieve is 85% by weight, d ₅₀ = 110μm, the bulk density of powder is 0.25g/cm ³ , using melting ¹³ C-NMR spectrum in Agilent DD2 600MHz solid system with high temperature wide cavity magic angle Rotary attachments yield polyethylene branched content <1/100,000C.

Example 10

Replace the 30L stainless steel stirred polymerization kettle with N ₂ successively, add AlEt ₃ (10mL) into the kettle with 8kg hexane under 0.4MPa nitrogen, control the stirring speed at 250rpm, preheat the temperature in the kettle to about 60°C, and then use 0.4MPa Under the condition of nitrogen pressure, use 2kg hexane to flush 30mg CAT-1 into the polymerization kettle, activate for 10min, then remove the nitrogen pressure in the kettle, and then feed ethylene gas to make the pressure in the kettle reach 0.4MPa, and control the temperature in the kettle to 80 ℃, stop feeding ethylene after 2 hours of polymerization, use a circulating constant temperature oil bath to lower the temperature in the kettle to below 50 ℃, vent the gas in the system and discharge the material, and obtain a granular polymer of 0.86kg after drying, with a viscosity-average molecular weight of 1.5 million , the sieving rate of 100-mesh mesh sieve is 90% by weight, d ₅₀ = 80μm, the bulk density of powder is 0.20g/cm ³ , using melting ¹³ C-NMR spectrum in Agilent DD2 600MHz solid system with high temperature wide cavity magic angle Rotary attachments yield polyethylene branched content <1/100,000C.

Example 11

Replace the 30L stainless steel stirred polymerization kettle with N ₂ successively, add AlEt ₃ (10mL) into the kettle with 8kg hexane under 0.4MPa nitrogen, control the stirring speed at 250rpm, preheat the temperature in the kettle to about 50°C, and then use 0.4MPa Under the condition of nitrogen pressure, use 2kg hexane to flush 30mg CAT-1 into the polymerization kettle, activate for 10min, then remove the nitrogen pressure in the kettle, and then feed ethylene gas to make the pressure in the kettle reach 0.4MPa, and control the temperature in the kettle to 60 ℃, stop feeding ethylene after 2 hours of polymerization, use a circulating constant temperature oil bath to lower the temperature in the kettle to below 50 ℃, vent the gas in the system and discharge the material, and obtain 3.66kg of granular polymer after drying, with a viscosity-average molecular weight of 5.8 million , the sieving rate of 100-mesh mesh sieve is 90% by weight, d ₅₀ = 100μm, the bulk density of powder is 0.30g/cm ³ , using melting ¹³ C-NMR spectrum in Agilent DD2 600MHz solid system with high temperature wide cavity magic angle Rotary attachments yield polyethylene branched content <1/100,000C.

Example 12

Replace the 30L stainless steel stirred polymerization kettle with N ₂ successively, add AlEt ₃ (10mL) into the kettle with 8kg hexane under 0.4MPa nitrogen, control the stirring speed at 250rpm, preheat the temperature in the kettle to about 30°C, and then use 0.4MPa Under the condition of nitrogen pressure, use 2kg hexane to flush 30mg CAT-1 into the polymerization kettle, activate for 10min, then remove the nitrogen pressure in the kettle, and then feed ethylene gas to make the pressure in the kettle reach 0.4MPa, and control the temperature in the kettle to 40 ℃, stopped feeding ethylene after 2 hours of polymerization, vented the gas in the system and discharged, and obtained 1.06 kg of granular polymer after drying, with a viscosity-average molecular weight of 8.3 million, and a sieving rate of 92% by weight through a 100-mesh mesh sieve. d ₅₀ ＝99μm, the powder bulk density is 0.28g/cm ³ , and the polyethylene branch content obtained by melting ¹³ C-NMR spectrum in AgilentDD2 600MHz solid system with high-temperature wide-cavity magic-angle rotating attachment is less than 1/100,000C.

Example 13 Trial production experiment of industrialized production equipment

The 32m ³ stainless steel stirring polymerization kettle was replaced with _N2 three times, ethylene twice, 10 tons of hexane was added, and 150kg of _Et3Al hexane solution with a mass concentration of 1% was added, and the catalyst CAT-1 330mL ( Contains about 70g of solid catalyst) into the reaction kettle, remove the nitrogen pressure in the kettle, then feed ethylene and gradually increase the ethylene reaction pressure to 0.4MPa, control the polymerization temperature fluctuation range between 69.5°C and 70.5°C; after 5.5 hours of polymerization , stop feeding ethylene, discharge to the filter kettle, add oil and wash in the filter kettle, vacuum dry for about 3 hours, discharge and pack to obtain the product polyethylene particles, the specific results are shown in the table below.

Example 14 Preparation of Microporous Filtration Products by Ultra-high Molecular Weight Polyethylene Microparticles

The ultra-high molecular weight polyethylene microparticles of Example 8 Batch 1 were used to prepare microporous filter materials. Weigh 30g of ultra-high molecular weight polyethylene particles, 0.5g of polyethylene wax, and 0.1g of calcium stearate, put them in a beaker, stir and mix evenly, put them into a mold and carry out pressureless sintering on a molding machine, the sintering temperature is 180-220°C , the sintering time is 10-20min, and finally the ultra-high molecular weight polyethylene microporous filter product is obtained by passing water to cool down (Figure 4). The solid insoluble matter filtration efficiency is greater than 99.8%, and the permeability is excellent. The pressure difference between the front and rear of the control filter is less than 0.2MPa, The throughput of pure water reaches 17-20m ³ /h, and the performance test of microporous filter products is as follows:

All documents mentioned in this application are incorporated by reference in this application as if each were individually incorporated by reference. In addition, it should be understood that after reading the above teaching content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims (19)

1. A microparticle of ultra-high molecular weight polyethylene, characterized in that, the microparticle has the following characteristics: (a) the viscosity-average molecular weight is 1.5-8 million g/mol; (b) ≥85wt% can pass through a 100-mesh mesh sieve, and the particle diameter (d50) is 80μm ≤ d50 ≤ 110μm; And in the microparticles, the number of alkane branch chains on the polymer chain is <1/100,000C, that is, the number of alkane branch chains in 100,000 carbon atoms is <1; The powder bulk density of the particles is 0.20-0.30 g/cm3. 2. The polyethylene microparticle according to claim 1, characterized in that, the viscosity-average molecular weight of the microparticle is 1.5-4 million g/mol. 3. The polyethylene microparticles according to claim 1, characterized in that, the d50 of the microparticles is 90 μm ≤ d50 ≤ 100 μm. 4. The polyethylene microparticles according to claim 1, characterized in that, the bulk density of the microparticles is 0.22-0.28 g/cm3. 5. The polyethylene microparticles according to claim 1, characterized in that, the bulk density of the microparticles is 0.22-0.26 g/cm3. 6. The preparation method of polyethylene microparticles as claimed in claim 1, is characterized in that, comprises the step: contact with ethylene with catalyst and co-catalyst and carry out catalytic polymerization reaction, thereby obtain described ultrahigh molecular weight polyethylene microparticles; Wherein, Described catalyst is prepared by the following method: (a) Use magnesium source to contact with C1-C10 alcohol and react at 60-120°C, then add nano-silica gel, cool down to below -30°C to obtain precursor slurry P-I; (b) Using the precursor slurry P-I obtained in step (a) to contact the alkylaluminum at a temperature lower than -30°C, and then raising the temperature to 60-120°C for 2-6 h to obtain the precursor slurry P-II; (c) Use the precursor slurry P-II obtained in step (b) to cool down to below -30 °C, contact with the inert hydrocarbon solution of titanium compound for 0.5-3 h, then raise the temperature to 60-120 °C and keep for 2-6 h, Obtain catalyst slurry C-III; (d) filter the catalyst slurry C-III obtained in step (c) to obtain a catalyst; The titanium compound is selected from the following group: TiCl4, TiR4, or alkyl complexes shown in structural formula I-IV; wherein R is C1-C6 alkyl, allyl, benzyl, NMe2:

Wherein, X is SR5 or P(R5)2; R1, R2, R3, R4, R5 are independently substituted or unsubstituted groups selected from the group consisting of: C1-C6 alkyl, C2-C6 alkenyl, C3-C8 cycloalkyl, C6-C10 aryl , halogenated C3-C8 cycloalkyl, 5-7 membered heteroaryl; Or R3 and R4, and the carbon atoms connected to them together form a 5-7 membered saturated, partially unsaturated or aromatic carbocyclic or heterocyclic ring; R6 is selected from the group consisting of C1-C6 alkyl, NH2, N(C1-C6 alkyl)2, allyl, benzyl, C1-C6 silyl; R7 is selected from the group consisting of C1-C6 alkyl, C2-C6 alkenyl or C3-C8 cycloalkyl; Wherein, the skeleton of the heteroaryl group has 1-3 heteroatoms selected from the group consisting of N, S(=O), P or O; The "substituted" refers to being substituted by one or more substituents selected from the following group: halogen, C1-C6 alkyl, halogenated C1-C6 alkyl, C1-C6 alkoxy, halogenated C1-C6 alkoxy. 7. The method according to claim 6, wherein said R is selected from the group consisting of methyl, ethyl, propyl, butyl, allyl, benzyl, or NMe2. 8. The method according to claim 6, wherein said R is selected from the group consisting of methyl, ethyl, propyl, butyl, NH2, N(C1-C6 alkyl)2, alkenyl Propyl, benzyl, or C1-C6 silyl. 9. The method of claim 6, wherein the method comprises: (a) Under inert gas protection conditions, add anhydrous magnesium chloride to a mixture of an inert hydrocarbon solvent and a C1-C10 alcohol greater than or equal to 2 equivalents of magnesium chloride for contact, react at 60-120 °C to form a uniform solution, and add nano Silica gel is used to prepare the composite carrier, and then the temperature is lowered to below -30°C to obtain the precursor slurry P-I; in the above reaction, the amount of anhydrous magnesium chloride is used as 1 equivalent; (b) The precursor slurry P-I obtained in step (a) is contacted with alkylaluminum for at least 1 h at a temperature lower than -30 °C, and then heated to 60-120 °C for 2-6 h to obtain the precursor slurry P-II ; (c) Cooling the precursor slurry P-II obtained in step (b) to below -30°C, contacting the titanium compound inert hydrocarbon solution for 0.5-3 h, then raising the temperature to 60-120°C for 2-6 h, Obtain catalyst slurry C-III; (d) filter the catalyst slurry C-III obtained in step (c) to obtain a catalyst. 10. The method according to claim 9, characterized in that, in the step (a), the cooling rate is 1-10° C./min. 11. The method according to claim 9, characterized in that, in the step (a), the cooling rate is 1-5° C./min. 12. The method according to claim 9, characterized in that, in the step (a), the amount of the C1-C10 alcohol charged is 2-6 equivalents. 13. The method according to claim 9, characterized in that, in the step (b), the heating rate is 1-10°C/min. 14. The method according to claim 9, characterized in that, in the step (c), the cooling rate is 1-10 °C/min, and the heating rate is 1-10 °C/min. 10°C/min. 15. The method according to claim 7, characterized in that, the preparation method of the catalyst further comprises the step of: (e) drying the catalyst obtained in step (d) to obtain catalyst powder. 16. The method according to claim 7, characterized in that, in the preparation of the catalyst, the C1-C10 alcohol described in step (a) is selected from the group consisting of methanol, ethanol, n-propanol, n-butanol , n-pentanol, n-hexanol, 2-ethylhexanol, n-octanol, or combinations thereof; and/or In the preparation of the catalyst, the alkylaluminum in the step (b) is selected from the group consisting of ethylaluminum dichloride, diethylaluminum chloride, triethylaluminum, triisobutylaluminum, ethyl sesquichloride butylaluminum, or butylaluminum sesquichloride; and/or In the catalyst preparation, the molar ratio of titanium compound to magnesium chloride in step (c) is 0.3-0.8:1. 17. The method according to claim 7, characterized in that, in the preparation of the catalyst, the molar ratio of the titanium compound to the magnesium chloride in step (c) is 0.4-0.6:1. 18. A microporous filtration product, characterized in that said product is prepared from ultra-high molecular weight polyethylene particles according to any one of claims 1-6. 19. The preparation method of product as claimed in claim 18, is characterized in that, comprises the step: (i) using polyethylene wax and calcium stearate as composite additives, and mixing them uniformly with the ultra-high molecular weight polyethylene particles described in claims 1-6 to obtain a mixed material; (ii) putting the said into a mold for pressureless sintering; (iii) cooling down to obtain ultra-high molecular weight polyethylene microporous filter products.

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