CN106279476A - Super high molecular weight ultra-fine propylene polymerization powder and preparation method thereof - Google Patents

Abstract

The invention relates to a propylene polymer powder with ultra-high molecular weight and ultra-fine particle size and a preparation method thereof. The viscosity-average molecular weight (Mv) of the propylene polymer is greater than 1×10 ⁶ , and the propylene polymer powder is spherical particles , the average particle size is 10μm-200μm, the standard deviation is 2μm-15μm, and the bulk density is 0.1g/mL-0.4g/mL. The method has simple steps, is easy to control, has high repeatability, and can realize industrialization. The powder of the invention has both ultra-high molecular weight and ultra-fine particle size range, is particularly suitable for processing and application, and is easy to realize graft modification, greatly expanding the application field and scope of application of the ultra-high molecular weight propylene polymer.

Description

Ultrahigh molecular weight ultrafine propylene polymer powder and preparation method thereof

technical field

The invention belongs to the field of polyolefin polymer materials, and in particular relates to a propylene polymer powder with ultra-high molecular weight and ultra-fine particle size and a preparation method thereof.

Background technique

Both ultra-high molecular weight propylene polymer (UHMWPP) and ultra-high molecular weight polyethylene (UHMWPE) are flexible chain polymers with regular structure and excellent crystallization performance. Compared with UHMWPE, UHMWPP also has better adhesion and lower service temperature. High, low creep and other advantages. However, due to the extremely high viscosity and poor melt flow properties of ultra-high molecular weight polymers in the molten state (the melt flow index is almost zero), it is difficult to process them by general thermal processing methods. After decades of development, the processing technology of UHMWPE has developed from the initial compression-sintering molding to various molding methods such as extrusion, blow molding and injection, and solution spinning molding. However, the processing and application of UHMWPP have developed slowly. On the one hand, it is difficult to synthesize ultra-high molecular weight propylene polymers. Under normal polymerization conditions, only propylene polymer resins with a molecular weight of hundreds of thousands can be obtained. On the other hand, UHMWPP is more difficult to process than UHMWPE.

The development of new processing methods is a solution, and how to prepare UHMWPP with better processing performance and easier processing is also a more fundamental and effective solution, which has a good development prospect.

Contents of the invention

One of the objects of the present invention is to provide a method for preparing ultra-high molecular weight and ultra-fine particle diameter propylene polymer powder.

The second object of the present invention is to provide a powder prepared by the above method, which has excellent processability.

In order to achieve the above object, the present invention provides a method for preparing an ultrahigh molecular weight ultrafine particle size propylene polymer powder, which comprises the following steps:

Under the action of a catalyst, propylene or propylene and comonomers undergo a polymerization reaction, wherein the temperature of the polymerization reaction is 30-105°C, and the volume fraction of propylene is greater than or equal to 98%;

The catalyst is prepared by a method comprising the following steps:

(a) magnesium halide, alcohol compound, auxiliary agent, part of the internal electron donor and solvent are mixed to prepare mixture I;

(b) Add the above-mentioned mixture I into the reactor, preheat to -30°C to 30°C, and add the titanium compound dropwise; or, add the titanium compound to the reactor, preheat to -30°C to 30°C, add dropwise the above-mentioned mixture I;

(c) After the dropwise addition is completed, the temperature of the reaction system is raised to 90° C. to 130° C. after 30 minutes to 3 hours, and the remaining internal electron donor is added to continue the reaction;

(d) filter out the liquid in the reaction system, add the remaining titanium compound, and continue the reaction;

(e) After the reaction is completed, post-processing obtains the catalyst;

The viscosity-average molecular weight (Mv) of the prepared propylene polymer is greater than 1×10 ⁶ ; the propylene polymer powder is a spherical particle with an average particle diameter of 10 μm-200 μm, a standard deviation of 2 μm-15 μm, and a bulk density of 0.1 g/mL-0.4g/mL.

According to the present invention, the particle size distribution of the propylene polymer powder is close to a normal distribution.

According to the present invention, the comonomer is a C _2-20 alpha-olefin, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonane One or more of ene, 1-decene, 1-undecene or 1-dodecene. Preferably, the comonomer is one or both of ethylene and 1-butene. The mole percentage of the comonomer is 0-10 mol%, preferably 0-5 mol%.

According to the present invention, the temperature of the polymerization reaction is preferably 40-80°C.

According to the present invention, the volume fraction of propylene is greater than or equal to 99%, more preferably greater than or equal to 99.8%, still more preferably greater than or equal to 99.9%.

According to the present invention, in the comonomer (such as ethylene or 1-butene), the carbon monoxide content is less than 5 ppm, the carbon dioxide content is less than 15 ppm, and the conjugated diene content is less than 10 ppm.

The present invention also provides ultra-high molecular weight and ultra-fine particle size propylene polymer powder prepared by the above preparation method, the viscosity-average molecular weight (Mv) of the propylene polymer is greater than 1×10 ⁶ ; the propylene polymer powder is Spherical particles, the average particle size is 10μm-200μm, the standard deviation is 2μm-15μm, and the bulk density is 0.1g/mL-0.4g/mL. Preferably, the particle size distribution of the propylene polymer powder is close to a normal distribution.

According to the present invention, the propylene polymer is a propylene homopolymer or a propylene copolymer, and the comonomer in the propylene copolymer is a C _2-20 α-olefin, such as ethylene, 1-butene, 1-pentene, One or more of 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene or 1-dodecene. Preferably, the comonomer is one or both of ethylene and 1-butene. The mole percentage of the comonomer is 0-10 mol%, preferably 0-5 mol%.

According to the present invention, the viscosity-average molecular weight (Mv) of the propylene polymer is greater than or equal to 1.5×10 ⁶ , preferably 1.5×10 ⁶ to 4.0×10 ⁶ ; the molecular weight distribution Mw/Mn of the propylene polymer is 2 to 15, preferably 3-10, more preferably 4-8.

According to the present invention, the average particle size of the propylene polymer powder is preferably 20 μm-180 μm, more preferably 30 μm-150 μm; the standard deviation is preferably 5 μm-15 μm, more preferably 6 μm-12 μm, and more preferably 8 μm-150 μm. 10 μm; the bulk density of the powder is preferably 0.15 g/mL-0.35 g/mL.

Beneficial effects of the present invention:

The present invention proposes a brand-new method for preparing ultra-high molecular weight and ultra-fine particle size propylene polymer powder. In the method, an ultra-high molecular weight polymer powder is synthesized by controlling the polymerization temperature, monomer purity and adjusting the preparation steps of the catalyst. The ultra-fine particle size propylene polymer powder has simple steps, easy control and high repeatability, and can realize industrialization.

The present invention synthesized a propylene polymer powder with both ultra-high molecular weight and ultra-fine particle size range for the first time. The research found that the powder with the above characteristics is especially suitable for processing and application, and it is easy to achieve graft modification. The application field and scope of application of the ultra-high molecular weight propylene polymer are greatly expanded. At the same time, the propylene polymer powder also has the following excellent properties: first, the wear resistance is very excellent, which is several times higher than the wear resistance index of ordinary carbon steel and copper; second, due to the ultra-high molecular weight, the molecular The chain is super long, which makes the impact strength of the material high; again, the chemical corrosion resistance of the propylene polymer powder is stronger than that of general polyolefin; finally, the material has a wide temperature range, and can be used at lower or higher temperatures Can maintain good toughness and strength.

detailed description

[Catalyst preparation method]

The catalyst used in the preparation method of the present invention can be prepared by the method disclosed in the invention patent application submitted by the applicant (application number 201510271254.1), the entirety of which is incorporated in this application as a reference.

Specifically, the catalyst used in the preparation method of the present invention is prepared by a method comprising the following steps:

(a) magnesium halide, alcohol compound, auxiliary agent, part of the internal electron donor and solvent are mixed to prepare mixture I;

(b) Add the above-mentioned mixture I into the reactor, preheat to -30°C to 30°C, and add the titanium compound dropwise; or, add the titanium compound to the reactor, preheat to -30°C to 30°C, add dropwise the above-mentioned mixture I;

(c) After the dropwise addition is completed, the temperature of the reaction system is raised to 90° C. to 130° C. after 30 minutes to 3 hours, and the remaining internal electron donor is added to continue the reaction;

(d) filter out the liquid in the reaction system, add the remaining titanium compound, and continue the reaction;

(e) After the reaction is completed, post-treatment to obtain the catalyst.

In the present invention, said step (b) is replaced by the following step (b'):

(b') configuration comprising mixture II of nanoparticles, dispersant and solvent;

Add the above-mentioned mixture I and mixture II to the reactor to obtain a mixture of the two, preheat to -30°C to 30°C, and add the titanium compound dropwise; or,

Add a titanium compound into the reactor, preheat to -30°C to 30°C, and add the above-mentioned mixture of mixture I and mixture II dropwise.

In the present invention, the mixture I is preferably prepared according to the following method: mix the magnesium halide and the alcohol compound in an organic solvent, heat up and keep it warm, add auxiliary agents and part of the internal electron donor, and react at a certain temperature to obtain Stable and homogeneous mixture I. The alcohol compound is selected from one or more of C _1- C ₁₅ aliphatic alcohol compounds, C ₃ -C ₁₅ cycloalkanol compounds and C ₆ -C ₁₅ aromatic alcohol compounds, preferably Methanol, ethanol, ethylene glycol, n-propanol, isopropanol, 1,3-propanediol, butanol, isobutanol, hexanol, heptanol, n-octanol, isooctyl alcohol, nonanol, decanol, sorbitol One or more of alcohol, cyclohexanol and benzyl alcohol, more preferably ethanol, butanol, hexanol and isooctyl alcohol. The internal electron donor is at least one of monoester, diester, monoether and diether compounds, more preferably selected from diester or diether. The solvent is selected from at least one of straight-chain alkanes with 5-20 carbons, branched-chain alkanes with 5-20 carbons, aromatic hydrocarbons with 6-20 carbons or their halogenated hydrocarbons, preferably toluene and chlorobenzene , at least one of dichlorobenzene or decane. In the present invention, magnesium halide has the effect of carrier in the catalyst that can directly obtain submicron-sized polyolefin particles in the preparation, is one of the compositions of traditional Ziegler-Natta catalyst, can make the prepared catalyst have suitable shape, At the same time, the carrier can disperse the active components on the surface of the carrier, obtain a higher specific surface area, and improve the catalytic efficiency of the active component per unit mass. In addition, the function of the alcohol compound is to dissolve the carrier, that is, the magnesium halide. During the preparation of the mixture I, the temperature of the obtained mixed solution is preferably 110°C-130°C, more preferably 130°C, the holding time is preferably 1-3 hours, more preferably 2-3 hours, the The reaction time after adding the auxiliary agent etc. is 0.5-2 hours, more preferably 1 hour. Therefore, the magnesium halide is dissolved by the alcohol compound at high temperature, and the compound I is obtained.

In the present invention, the mixture II is preferably prepared according to the following method: adding nanoparticles, a dispersant and a solvent into a reaction vessel, and performing ultrasonic treatment to obtain a uniform mixture II. The nanoparticles are preferably at least one of nano-silicon dioxide, nano-titanium dioxide, nano-zirconia, nano-nickel oxide, nano-magnesium chloride or nano-carbon spheres, more preferably nano-silicon dioxide and nano-titania. The particle size of the nanoparticles is preferably 1-80 nm, more preferably 10-50 nm. Preferably, the added mass of nanoparticles relative to the added mass of magnesium halide is 0%-200%, more preferably 0%-20%. The time of sonication is preferably 2 hours. In the present invention, nanoparticles are introduced as crystal seeds, and the purpose is to accelerate the molding of the carrier and reduce the particle diameter of the catalyst particles; dispersants and solvents, including ultrasonic treatment, are all in order to help the nanoparticles to disperse, so that each nanoparticle can be play the role of seed crystals.

In the present invention, in the mixture II of the step (b'), the nanoparticles are selected from at least one of nano-silica, nano-titanium dioxide, nano-zirconia, nano-nickel oxide, nano-magnesium chloride or nano-carbon spheres .

Preferably, the particle size of the nanoparticles is 1-80 nm, preferably 2-60 nm, more preferably 3-50 nm.

The added mass of the nanoparticles relative to the added mass of the magnesium halide is greater than 0% to less than or equal to 200%, preferably, the range of the added amount of the nanoparticles is greater than 0% to less than or equal to 20%.

In the present invention, in the mixture II of the step (b'), the solvent is selected from linear alkanes with 5-20 carbons, branched alkanes with 5-20 carbons, aromatic hydrocarbons with 6-20 carbons or at least one of their halogenated hydrocarbons.

The dispersant is selected from titanium tetrachloride, silicon tetrachloride or a mixture of the two.

In step (a), the mixing is carried out under heating and stirring to obtain a uniform and stable transparent mixture I.

In step (b'), ultrasonic dispersion treatment is carried out during configuration.

In step (b) or (b'), dropwise is slow dropwise.

In step (b) or (b'), the preferred reaction preheating temperature is -20°C to 30°C, more preferably -20°C to 20°C.

The reaction time of step (c) is 1-5 hours, preferably 2-3 hours.

The time for continuing the reaction in step (d) is 1-5 hours, preferably 2-3 hours.

The post-treatment in step (e) can be to wash the obtained product with hexane, and then dry; wherein, the number of times of washing can be 1-10 times, preferably 3-6 times.

In step (a), the magnesium halide is at least one selected from magnesium chloride, magnesium bromide or magnesium iodide.

In step (a), the auxiliary agent may be a titanate compound.

In step (b) or (b'), the general formula of the titanium compound is as shown in formula I:

Ti(R) _n X _(4-n)

Formula I

Wherein, R is a C1-C12 branched or linear alkyl group, X is a halogen, and n is 0, 1, 2 or 3.

In step (d), preferably, the temperature of the reaction system is raised to 90° C. to 130° C. over 40 minutes to 3 hours, more preferably the temperature of the reaction system is raised to 100° C. to 120° C. over 40 minutes to 2 hours.

It can be seen from the above scheme that the preparation method of the Ziegler-Natta catalyst involved in the present invention has a simple process and is easy for industrial production. Moreover, the Ziegler-Natta catalyst prepared by the present invention can obtain an average particle diameter of 10 μm-200 μm during the polymerization of propylene, a high degree of sphericity, a narrow particle size distribution, and a low bulk density (0.1-0.4 g/mL ) of propylene polymer particles. Through research, it is found that the catalyst prepared by the present invention is used for the propylene polymer particles obtained by propylene polymerization, compared with others, the particle size is 20-30 times lower, the particle size distribution is obviously narrowed and the bulk density can be as low as 0.1g/ mL.

[Preparation method of propylene polymer powder]

As mentioned above, the present invention provides a kind of preparation method of ultrahigh molecular weight ultrafine particle diameter propylene polymer powder, it comprises the following steps:

Under the action of a catalyst, propylene or propylene and comonomers undergo a polymerization reaction, wherein the temperature of the polymerization reaction is 30-105°C, and the volume fraction of propylene is greater than or equal to 98%;

The catalyst is prepared by the above catalyst preparation method.

The present invention finds through research that simply controlling the preparation method of the catalyst can indeed well realize the control of the particle size of the powder, but the molecular weight of the prepared propylene polymer is not high. The molecular weight of the polymer, the inventor has carried out many attempts, found through research, the temperature of control polymerization reaction and the purity of monomer are a kind of simple and effective method, and can not influence the particle diameter of described polymer Effective control even facilitates the preparation of narrower particle size ranges and lower bulk density ranges of polymers.

Through research, it is found that the temperature of the polymerization reaction is controlled at 30-105° C., and the volume fraction of propylene is controlled at 98% or more, so that ultra-high molecular weight propylene polymer can be prepared while controlling the particle size. Further preferably, the temperature of the polymerization reaction is 40-80°C. Further preferably, the volume fraction of propylene is greater than or equal to 99%; still more preferably, greater than or equal to 99.8%; still more preferably, greater than or equal to 99.9%. For the copolymerization, controlling the carbon monoxide content in the comonomer to be less than 5ppm, the carbon dioxide content to be less than 15ppm, and the conjugated diene content to be less than 10ppm is also beneficial to the realization of the purpose of the present invention.

In the present invention, the volume fraction of propylene is determined by the standard GB/T3392. The propylene volume fraction is an important index to characterize the purity of the propylene monomer.

[Propylene polymer powder]

As mentioned above, the powder of the present invention is an ultra-high molecular weight propylene polymer, the viscosity-average molecular weight (Mv) of the propylene polymer is greater than 1×10 ⁶ , the propylene polymer powder is spherical particles, and the average particle size is The diameter is 10μm-200μm, the standard deviation is 2μm-15μm, and the bulk density is 0.1g/mL-0.4g/mL. Preferably, the particle size distribution of the propylene polymer powder is close to a normal distribution. The average particle size is preferably 20 μm-180 μm, more preferably 30 μm-150 μm. The standard deviation is preferably 5 μm-15 μm, more preferably 6 μm-12 μm, further preferably 8 μm-10 μm. The bulk density is preferably 0.15g/mL-0.35g/mL. The ultra-high molecular weight propylene polymer with the above particle size and bulk density is especially suitable for graft modification. On the one hand, it greatly expands the modification space of the propylene polymer; on the other hand, the processing performance of the polymer is remarkable Improvement, suitable for the preparation of a wider range of products; thus, the application field of the polymer is effectively expanded.

At the same time, the propylene polymer powder of the present invention also has the following excellent properties: First, the wear resistance is very excellent, which is several times higher than the wear resistance index of metals such as ordinary carbon steel and copper; secondly, due to the ultra-high molecular weight, The molecular chain is super long, which makes the impact strength of the material high; again, the chemical corrosion resistance of the propylene polymer powder is stronger than that of general polyolefin; finally, the material has a wide temperature range, at lower or higher temperature Both can maintain good toughness and strength.

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through different specific implementation modes, and various modifications or changes can be made to the details in this specification based on applications in different aspects without departing from the spirit of the present invention.

Embodiment 1 propylene homopolymer and its preparation

In the reactor fully replaced by high-purity nitrogen, add 4.94g of anhydrous magnesium chloride, 18.9g of isooctyl alcohol, and 30ml of decane in sequence, raise the temperature to 130°C under stirring, and maintain it for 2 hours, then add 2.65g of tetrabutyl titanate The ester and 2.05g of diisobutyl phthalate were reacted at 130°C for 1 hour, and finally cooled to room temperature to form a homogeneous transparent solution, namely mixture I.

Add 200ml of titanium tetrachloride to the reaction kettle, stir and preheat to 0°C, add the mixture I dropwise to the titanium tetrachloride in about 2 hours. After the dropwise addition was completed, the temperature was raised to 110° C. within 2 hours. 1.23 g of internal electron donor diisobutyl phthalate was added. After reacting at this temperature for 2 hours, remove the reaction liquid, add 200ml of titanium tetrachloride again, and react for 2 hours. Finally, the reaction liquid was removed, and the remaining solid matter was washed with hexane at 60° C. for 10 times, and dried to obtain the catalyst.

Bulk polymerization of propylene:

Under the protection of high-purity nitrogen, dry and deoxygenate the 5L autoclave, add 20mg of the above-mentioned catalyst, 12ml of triethylaluminum and 3ml of external electron donor Donor-P, and then add 1200g of propylene, wherein the volume fraction of propylene is 99.9%, the polymerization reaction started, the system temperature was maintained at 45°C, and the reaction time was 60 minutes. The catalyst activity and polypropylene properties obtained are shown in Table 1.

Embodiment 2 propylene-ethylene copolymers and preparation thereof

The preparation method of catalyst is the same as embodiment 1.

Propylene-ethylene copolymerization:

Under the protection of high-purity nitrogen, dry and deoxygenate the 5L high-pressure reactor, add 20mg of the above-mentioned catalyst, 12ml of triethylaluminum and 3ml of external electron donor Donor-P, then add 1200g of propylene, and feed 40g of ethylene, among which, The volume fraction of propylene is 99.9%, the content of carbon monoxide in ethylene gas is less than 5ppm, the content of carbon dioxide is less than 15ppm, and the content of conjugated diene is less than 10ppm, the polymerization reaction starts, the system temperature is maintained at 75°C, and the reaction time is 60 minutes, the obtained Catalyst activity and properties of propylene-ethylene copolymer are shown in Table 1.

Embodiment 3 propylene homopolymer and its preparation

The preparation method of catalyst is the same as embodiment 1.

Bulk polymerization of propylene:

Under the protection of high-purity nitrogen, dry and deoxygenate the 5L autoclave, add 20mg of the above-mentioned catalyst, 12ml of triethylaluminum and 3ml of external electron donor Donor-P, and then add 1200g of propylene, wherein the volume fraction of propylene is 99.9%, the polymerization reaction started, the system temperature was maintained at 55°C, and the reaction time was 60 minutes. The catalyst activity and polypropylene properties obtained are shown in Table 1.

Embodiment 4 propylene homopolymer and its preparation

The preparation method of catalyst is the same as embodiment 1.

Bulk polymerization of propylene:

Under the protection of high-purity nitrogen, dry and deoxygenate the 5L autoclave, add 20mg of the above-mentioned catalyst, 12ml of triethylaluminum and 3ml of external electron donor Donor-P, and then add 1200g of propylene, wherein the volume fraction of propylene is 99.9%, the polymerization reaction started, the system temperature was maintained at 65° C., and the reaction time was 60 minutes. The catalyst activity and polypropylene properties obtained are shown in Table 1.

Catalytic activity of the Ziegler-Natta catalyst prepared by the embodiment of the present invention and the properties of the obtained propylene polymer

In the present invention, some other performances of the propylene polymers of Examples 1-4 are further detected, and it is found after testing that: (1) the wear resistance index of the propylene polymers of Examples 1-4 is higher than that of general carbon steel or copper. The grinding index is several times higher; (2) the impact strength of the propylene polymer of embodiment 1-4 is 2-5 times of the impact strength of ordinary polypropylene; (3) the resistance of the propylene polymer powder of embodiment 1-4 Chemical corrosion ability is stronger than that of general polyolefin; (4) the use temperature range of the propylene polymer powder of embodiment 1-4 is wider, at lower (such as minus 30 ℃) or higher temperature (such as 130 ℃) Can maintain good toughness and strength.

Comparative example 1-2

A method similar to that of Example 1 was adopted, except that the polymerization temperature and the purity of the monomers were different. The results are listed in Table 2.

Properties of the propylene polymers of Table 2 Comparative Examples 1-2

Claims (10)

1. a preparation method of ultrahigh molecular weight ultrafine particle diameter propylene polymer powder, is characterized in that, described method comprises the following steps: Under the action of a catalyst, propylene or propylene and comonomers undergo a polymerization reaction, wherein the temperature of the polymerization reaction is 30-105°C, and the volume fraction of propylene is greater than or equal to 98%; The catalyst is prepared by a method comprising the following steps: (a) magnesium halide, alcohol compound, auxiliary agent, part of the internal electron donor and solvent are mixed to prepare mixture I; (b) Add the above-mentioned mixture I into the reactor, preheat to -30°C to 30°C, and add the titanium compound dropwise; or, add the titanium compound to the reactor, preheat to -30°C to 30°C, add dropwise the above-mentioned mixture I; (c) After the dropwise addition is completed, the temperature of the reaction system is raised to 90° C. to 130° C. after 30 minutes to 3 hours, and the remaining internal electron donor is added to continue the reaction; (d) filter out the liquid in the reaction system, add the remaining titanium compound, and continue the reaction; (e) After the reaction is completed, post-processing obtains the catalyst; The viscosity-average molecular weight (Mv) of the prepared propylene polymer is greater than 1×10 ⁶ ; the propylene polymer powder is a spherical particle with an average particle diameter of 10 μm-200 μm, a standard deviation of 2 μm-15 μm, and a bulk density of 0.1 g/mL-0.4g/mL. 2. The preparation method according to claim 1, characterized in that the particle size distribution of the propylene polymer powder is close to a normal distribution. Preferably, the comonomer is a C _2-20 α-olefin, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene , 1-decene, 1-undecene or 1-dodecene in one or more. Preferably, the comonomer is one or both of ethylene and 1-butene. Preferably, the mole percentage of the comonomer is 0-10 mol%, preferably 0-5 mol%. 3. The preparation method according to claim 1 or 2, characterized in that the temperature of the polymerization reaction is preferably 40-80°C. 4. The preparation method according to any one of claims 1-3, characterized in that the volume fraction of the propylene is greater than or equal to 99%, more preferably greater than or equal to 99.8%, still more preferably greater than or equal to 99.9%. 5. according to the preparation method described in any one of claim 1-4, it is characterized in that, in described comonomer (such as ethylene or 1-butene), carbon monoxide content is less than 5ppm, and carbon dioxide is less than 15ppm, conjugated The diene content is less than 10 ppm. 6. the ultrahigh molecular weight ultrafine particle diameter propylene polymer powder obtained by the preparation method described in any one of claims 1-5, is characterized in that, the viscosity-average molecular weight (Mv) of described propylene polymer is greater than 1 ×10 ⁶ ; the propylene polymer powder is a spherical particle with an average particle diameter of 10 μm-200 μm, a standard deviation of 2 μm-15 μm, and a bulk density of 0.1 g/mL-0.4 g/mL. 7. The powder according to claim 6, characterized in that the particle size distribution of the propylene polymer powder is close to a normal distribution. Preferably, the propylene polymer is a propylene homopolymer or a propylene copolymer, and the comonomer in the propylene copolymer is a C _2-20 α-olefin, such as ethylene, 1-butene, 1-pentene, 1- One or more of -hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene or 1-dodecene. Preferably, the comonomer is one or both of ethylene and 1-butene. Preferably, the mole percentage of the comonomer is 0-10 mol%, preferably 0-5 mol%. 8. The powder according to claim 6 or 7, characterized in that the viscosity-average molecular weight (Mv) of the propylene polymer is greater than or equal to 1.5×10 ⁶ , preferably 1.5×10 ⁶ to 4.0×10 ⁶ ; The molecular weight distribution Mw/Mn of the propylene polymer is 2-15, preferably 3-10, and more preferably 4-8. 9. The powder according to any one of claims 6-8, characterized in that the average particle diameter of the propylene polymer powder is preferably 20 μm-180 μm, more preferably 30 μm-150 μm; the standard deviation is preferably 5 μm-15 μm, more preferably 6 μm-12 μm, and more preferably 8 μm-10 μm. 10. The powder according to any one of claims 6-9, characterized in that the bulk density of the powder is preferably 0.15g/mL-0.35g/mL.