Polypropylene, process for its preparation and use thereof

Abstract

This invention discloses a plasticizer-free polypropylene with ultra-high melt flow rate, its preparation method, and its applications. The plasticizer-free polypropylene with ultra-high melt flow rate has a melt flow rate (MFR) greater than 1500 g / 10 min, a xylene-soluble content less than 4 wt%, and a molecular weight distribution index of 4–7. The preparation of this plasticizer-free polypropylene with ultra-high melt flow rate does not involve peroxide degradation; it is obtained directly through polymerization during the polymerization process. This overcomes the problem of chemical degradation required when preparing polypropylene resin for meltblown applications in existing technologies. The invention employs a direct hydrogen conditioning method to prepare plasticizer-free polypropylene with ultra-high melt flow rate, which features the characteristics of being plasticizer-free and having a low xylene-soluble content.

Description

Technical Field

[0001] This invention relates to the technical field of olefin polymerization and polyolefins, specifically to a polypropylene with ultra-high melt flow rate that does not contain plasticizers, its preparation method, and its applications. Background Technology

[0002] Meltblown nonwoven fabric is a key filtration material in disposable medical surgical masks, medical N95 masks, and other products. It is primarily made from polypropylene as raw material, through processes including feeding, melt extrusion, fiber formation, fiber cooling, web formation, and reinforcement into fabric. The meltblown fibers can reach a diameter of 1-5 micrometers, characterized by numerous pores, a loose structure, and excellent wrinkle resistance. These ultrafine fibers with unique capillary structures increase the number of fibers and surface area per unit area, giving meltblown nonwoven fabric excellent filtration, shielding, heat insulation, and oil absorption properties. It can be used in air and liquid filtration materials, isolation materials, absorbent materials, mask materials, thermal insulation materials, oil-absorbing materials, and wiping cloths.

[0003] However, in the process of preparing meltblown nonwoven fabric using existing meltblown polypropylene materials, due to the high requirements for particle filtration efficiency, while achieving high filtration efficiency, there is also the characteristic of high resistance. This will lead to breathing difficulties when wearing the masks made from it.

[0004] Currently, the main materials on the market include those from Daelim (Korea) with melt flow rates of 900g / 10min and 1500g / 10min, Borealis's specialty material with a melt flow rate of 1200g / 10min, and ExxonMobil's PP3505G with a melt flow rate of 400g / 10min, PP3546G with a melt flow rate of 1200g / 10min, and PP3746G with a melt flow rate of 1500g / 10min. Currently, domestically available meltblown fabric resins suffer from drawbacks such as poor product flowability, unstable melt flow rate, high ash content, unpleasant odor, and easy nozzle clogging, and their melt flow rate is limited to 1500g / 10min.

[0005] The preparation processes for meltblown nonwoven fabric special materials are broadly divided into two types: one is the chemical degradation method, which is further divided into complete degradation and incomplete degradation methods. Currently, the incomplete degradation method is widely used in China. The degradation method requires the use of relatively expensive peroxides, resulting in high costs and high VOC levels. VOC removal treatment is necessary, making the process complex. Furthermore, small or trace amounts of peroxides or their reaction products inevitably exist in the meltblown fabric special material, leading to unpleasant odors and other issues. The other method involves direct polymerization using metallocene catalysts. However, this method requires high purity of raw materials such as propylene, low impurity content, and stable production control. Additionally, the high price of metallocene catalyst components and the large quantity of co-catalyst methylaluminoxane required in production contributes to the high cost. Therefore, currently, both imported and domestic materials are mostly produced using the chemical degradation method.

[0006] In addition, the demand for "plasticizer-free polypropylene" is increasing in the hygiene / personal care market.

[0007] Therefore, there is an urgent market need for a polypropylene material that does not require the addition of peroxides for degradation, is easy to produce and can be stably supplied, and can be used to prepare low-resistance, high-filtration-efficiency meltblown nonwoven fabrics. This material is free of plasticizers and has an ultra-high melt flow rate. Summary of the Invention

[0008] The technical problem to be solved by the present invention is that the preparation of polypropylene materials with ultra-high melt flow rate requires the addition of peroxides for degradation, or the production stability control is difficult, and there are plasticizers in the prior art. The present invention provides a polypropylene with ultra-high melt flow rate that does not contain plasticizers, as well as its preparation method and application.

[0009] To solve the above-mentioned technical problems, the first aspect of the present invention provides a polypropylene with ultra-high melt flow rate (MFR) that does not contain plasticizer.

[0010] According to some embodiments of the present invention, the plasticizer-free polypropylene with an ultra-high melt flow rate has a melt flow rate greater than 1500 g / 10 min under conditions of 230°C and 2.16 kg pressure.

[0011] According to some embodiments of the present invention, the plasticizer-free polypropylene with ultra-high melt flow rate has a melt flow rate of 1600g / 10min to 3500g / 10min, preferably 1800g / 10min to 3000g / 10min, under the conditions of a temperature of 230°C and a pressure of 2.16kg.

[0012] According to some embodiments of the present invention, the xylene-soluble content of the plasticizer-free polypropylene with ultra-high melt flow rate is less than 4 wt%.

[0013] According to some embodiments of the present invention, the plasticizer-free polypropylene with an ultra-high melt flow rate has a molecular weight distribution index (weight average / number average) of 4 to 7, preferably 4.5 to 6.5, as tested by gel permeation chromatography.

[0014] And / or, when the plasticizer-free polypropylene with ultra-high melt flow rate is analyzed by differential scanning calorimetry, at least two melting peaks appear on the DSC curve, one of which has a peak value of 150℃~159℃ and the other has a peak value of 160℃~170℃.

[0015] The second aspect provides a method for preparing polypropylene with ultra-high melt flow rate that is free of plasticizers, comprising polymerizing propylene under olefin polymerization conditions in the presence of a catalyst and hydrogen to obtain the polypropylene with ultra-high melt flow rate that is free of plasticizers, without the need for degradation by chemical degradation agents; during the polymerization process, the concentration of hydrogen is not less than 7000 ppm, preferably 8000 ppm to 17000 ppm; the catalyst comprises a catalyst component, an alkylaluminum compound, and an external electron donor; the catalyst component comprises a Ziegler-Natta catalyst that is free of plasticizers.

[0016] In the method for preparing polypropylene with ultra-high melt flow rate without plasticizer provided by the present invention, the catalyst described in the present invention can increase the hydrogen concentration during the polymerization process of polypropylene resin to 8000ppm~17000ppm. This significantly increases the hydrogen concentration, allowing for the preparation of polypropylene with ultra-high melt flow rate while maintaining the xylene-soluble content in the polypropylene resin within a low range, preventing resin stickiness and equipment blockage. Conversely, conventional catalysts in the art typically have a hydrogen concentration below 7000ppm during polymerization, and their hydrogen sensitivity is low. Even with increased hydrogen concentration, the resulting polypropylene melt flow rate is not very high. Furthermore, a unilateral and significant increase in hydrogen concentration can lead to an increase in the xylene-soluble content in the polypropylene resin, causing resin stickiness, equipment blockage, and production accidents.

[0017] According to some embodiments of the present invention, the preparation method includes pre-contacting the catalyst component, alkylaluminum compound, and external electron donor before the polymerization reaction; preferably, the pre-contact reaction temperature is -10℃ to 30℃, more preferably 0℃ to 20℃, more preferably 5℃ to 15℃, for example 10℃; the pre-contact reaction can significantly improve the polymerization activity of the catalyst and the apparent density of polypropylene, while enhancing the resistance of the catalyst active center to impurity interference, thereby reducing the ash content and breakage of polypropylene particles.

[0018] According to some embodiments of the present invention, the preparation method further includes, after the pre-contact reaction and before the polymerization reaction, pre-polymerizing the catalyst with propylene and / or other α-olefin monomers, wherein a small amount of hydrogen is added or no hydrogen is added during the pre-polymerization reaction, wherein the pre-polymerization reaction temperature is 10°C to 50°C, preferably 15°C to 30°C, more preferably 17°C to 20°C, for example 18°C.

[0019] According to some embodiments of the present invention, the polymerization reaction can be carried out according to various existing methods. Specifically, it can be carried out under the protection of an inert gas, in a liquid monomer or an inert solvent containing the monomer, or in the gas phase, or through a combined gas-liquid phase polymerization process. The polymerization temperature is generally 20°C to 150°C, preferably 60°C to 90°C, for example 69°C. The polymerization pressure is 0.02 MPa to 10 MPa, preferably 1 MPa to 6 MPa, more preferably 2 MPa to 5 MPa, for example 3.9 MPa; all pressures in this invention refer to gauge pressure. During the polymerization process, hydrogen can be added to the reaction system as a polymer molecular weight regulator to adjust the melt flow rate of the polymer. The concentration of hydrogen is greater than or equal to 7000 ppm, preferably 8000 ppm to 17000 ppm, for example 10000 ppm, 11000 ppm, or 13000 ppm. The polymerization time of propylene and catalyst is preferably 0.5 h to 6 h, more preferably 1 h to 2 h, for example 1 h. Furthermore, the types and amounts of inert gases and solvents used in the polymerization reaction of olefins are well known to those skilled in the art and will not be described in detail here.

[0020] According to some embodiments of the present invention, the preparation method of polypropylene further includes: after the reaction in the polymerization reactor, the polymer powder is subjected to flash evaporation and steam evaporation to reduce the volatile content; the process parameters of the flash evaporation and steam evaporation are well known to those skilled in the art and will not be described in detail here.

[0021] According to some embodiments of the present invention, the catalyst component is a reaction product containing the following components:

[0022] (i) Magnesium-containing compounds;

[0023] (ii) Titanium-containing compounds;

[0024] and (iii) internal electron donors;

[0025] The internal electron donor is a complex of any one or more of the following non-plasticizer compounds: ethers, alcohol esters, diesters, monoesters, cyano esters, diketones, and diamines.

[0026] According to some embodiments of the present invention, the internal electron donor is a 1,3-diether compound of formula (1):

[0027] Equation (1)

[0028] In equation (1), R Ⅰ R Ⅱ R Ⅲ R Ⅳ R Ⅴ and R Ⅵ Whether they are the same or different, they are each independently selected from hydrogen, halogen atoms, and C1-C atoms. 20 Straight-chain alkyl, C3-C 20 Branched alkyl groups, C3-C 20 cycloalkyl, C6-C 20 aryl, C7-C 20 Any one of the aryl alkyl groups, and R Ⅶ and R Ⅷ Whether they are the same or different, each is independently selected from C1-C 20 Straight-chain alkyl, C3-C 20 Branched alkyl groups, C3-C 20 cycloalkyl, C6-C 20 aryl, C7-C 20 alkylaryl, C7-C 20 Any one of the aryl alkyl groups; R Ⅰ R Ⅱ R Ⅲ R Ⅳ R Ⅴ and R Ⅵ The groups are optionally linked together to form a ring.

[0029] According to some embodiments of the present invention, the 1,3-diether compound is selected from 2-(2-ethylhexyl)-1,3-dimethoxypropane, 2-isopropyl-1,3-dimethoxypropane, 2-butyl-1,3-dimethoxypropane, 2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-1,3-dimethoxypropane, 2-phenyl-1,3-dimethoxypropane, 2-(2-phenylethyl)-1,3-dimethoxypropane, 2-(2-cyclohexylethyl)-1,3-dimethoxypropane, 2-(p-chlorophenyl)-1,3-dimethoxypropane, 2-(diphenylmethyl)-1,3-dimethoxypropane, 2,2-dicyclohexyl-1,3-dimethoxypropane, and 2,2-dicyclohexyl-1,3-dimethoxypropane. Alkane, 2,2-dicyclopentyl-1,3-dimethoxypropane, 2,2-diethyl-1,3-dimethoxypropane, 2,2-dipropyl-1,3-dimethoxypropane, 2,2-diisopropyl-1,3-dimethoxypropane, 2,2-dibutyl-1,3-dimethoxypropane, 2-methyl-2-propyl-1,3-dimethoxypropane, 2-methyl-2-benzyl-1,3-dimethoxypropane, 2-methyl-2-ethyl-1,3-dimethoxypropane, 2-methyl-2-isopropyl-1,3-dimethoxypropane, 2-methyl-2-phenyl-1,3-dimethoxypropane, 2-methyl-2-cyclohexyl-1,3-dimethoxypropane, 2,2-bis(2-cyclohexyl) 2-Methyl-2-isobutyl-1,3-dimethoxypropane, 2-methyl-2-(2-ethylhexyl)-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane, 2,2-dibenzyl-1,3-dimethoxypropane, 2,2-bis(cyclohexylmethyl)-1,3-dimethoxypropane, 2-isobutyl-2-isopropyl-1,3-dimethoxypropane, 2-(1-methylbutyl)-2-isopropyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, 2-phenyl-2-isopropyl-1,3-di At least one of methoxypropane, 2-phenyl-2-sec-butyl-1,3-dimethoxypropane, 2-benzyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclopentyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclopentyl-2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclohexyl-2-sec-butyl-1,3-dimethoxypropane, 2-isopropyl-2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-2-cyclohexylmethyl-1,3-dimethoxypropane, and 9,9-dimethoxymethylfluorene; for example, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane.

[0030] According to some embodiments of the present invention, the internal electron donor further includes a phosphate ester compound represented by formula (2):

[0031] (2)

[0032] In equation (2), R 13 R 14 and R 15 Whether the same or different, each is independently selected from C1-C4 straight-chain alkyl, C3-C4 branched alkyl, C3-C 20 cycloalkyl, C6-C 20 aryl, C7-C 20 alkylaryl and C7-C 20 Any one of the aralkyl groups, optionally, the C6-C 20 aryl, C7-C 20 alkylaryl and C7-C 20 In the aralkyl group, the hydrogen atom on the benzene ring is replaced by a halogen atom; preferably, R 13 R 14 and R 15 Whether the same or different, each is independently selected from C1-C4 straight-chain alkyl, C3-C4 branched alkyl, C3-C 12 cycloalkyl, C6-C 12 aryl, C7-C 12 alkylaryl and C7-C 12 Any one of the aryl, alkylaryl, and aryl groups, wherein the hydrogen atom on the benzene ring in the aryl, alkylaryl, and aryl groups is optionally replaced by a halogen atom; more preferably, R 13 R 14 and R 15 Whether the groups are the same or different, each independently selected from any one of C1-C4 straight-chain alkyl, C3-C4 branched alkyl, C3-C6 cycloalkyl, C6-C8 aryl, C7-C8 alkylaryl, and C7-C8 aralkyl, wherein the hydrogen atom on the benzene ring in the aryl, alkylaryl, and aralkyl groups is optionally substituted with a halogen atom; more preferably, R 13 R 14 and R 15 They may be the same or different, each independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, phenyl, tolyl, dimethylphenyl, ethylphenyl, benzyl, methylbenzyl or phenethyl.

[0033] According to some embodiments of the present invention, the phosphate ester compound is selected from at least one of trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, tricresyl phosphate, triisopropylphenyl phosphate, trimethoxyphenyl phosphate, dimethyl phenyl phosphate, toluene dibutyl phosphate, isopropylphenyl dimethyl phosphate, isopropylphenyl diethyl phosphate, isopropylphenyl dibutyl phosphate, phenyl xylene phosphate, phenyl diisopropylphenyl phosphate, p-toluene dibutyl phosphate, m-toluene dibutyl phosphate, p-isopropylphenyl dimethyl phosphate, p-isopropylphenyl diethyl phosphate, p-tert-butylphenyl dimethyl phosphate, and o-toluene-p-di-tert-butylphenyl phosphate; for example, tributyl phosphate.

[0034] According to some embodiments of the present invention, the molar ratio of the phosphate ester compound to the 1,3-diether compound is 0.03 to 0.3:1, preferably 0.07:1. When the molar ratio of the phosphate ester compound to the diether compound is 0.03 to 0.3:1, the two internal electron donors can achieve a very perfect coordination, thereby more effectively improving the hydrogen sensitivity and stereotactic orientation of the catalyst. This property is very important for the preparation of plasticizer-free polypropylene with ultra-high melt flow rate by direct hydrogenation.

[0035] The present invention does not impose any particular restrictions on the content of magnesium, titanium and internal electron donor in the preparation of catalyst components. The content can be any value found in conventional catalyst components in the art. Preferably, the molar ratio of magnesium source (calculated as magnesium element), titanium source (calculated as titanium element) and internal electron donor is 1:15-150:0.1-0.9, more preferably 1:25-120:0.15-0.6; for example, 1:60:0.2.

[0036] In this invention, the magnesium source can be any existing magnesium-containing compound that can be used as a catalyst for olefin polymerization. For example, the magnesium source can be magnesium halide, magnesium alcohol or haloalcohol and magnesium halide adduct support, etc.; the magnesium halide can be, for example, magnesium chloride and / or magnesium bromide; the magnesium alcohol can be, for example, magnesium diethoxy; the magnesium haloalcohol can be, for example, magnesium ethoxychloride; the types of magnesium halide adduct support are known to those skilled in the art, for example, they can be magnesium halide adduct supports disclosed in CN1091748A, CN101050245A, CN101486722A, 201110142357.X, 201110142156.X and 201110142024.7, and all relevant contents disclosed in these patents are incorporated herein by reference. The specific preparation method of the magnesium halide adduct support may include the following steps: mixing the components that form the magnesium halide adduct, heating the mixture to generate a magnesium halide adduct melt at a temperature of 90-140℃, subjecting it to high shear in a dispersion medium, and then placing it in a cooling medium to form spherical magnesium halide adduct particles. After washing and drying, a spherical support is obtained. An internal electron donor may be selectively added during or after this process. The high shear can be obtained using conventional methods, such as high-speed stirring (e.g., CN1330086), spraying (e.g., US6020279), high-gravity rotating bed (e.g., CN1580136A), and emulsifier method (e.g., CN1463990A). The dispersion medium may be, for example, any one or more hydrocarbon inert solvents, such as kerosene, white oil, silicone oil, paraffin oil, petroleum jelly, etc. The cooling medium may be, for example, any one or more of pentane, hexane, heptane, petroleum ether, raffinate oil, etc.

[0037] According to the present invention, in the preparation of catalyst components for olefin polymerization, the titanium source can be a conventional choice in the art; for example, the titanium source can be of the general formula Ti(OR′). 3-a Z a And / or Ti(OR′) 4-b Z b The substance, wherein R′ is C1-C 20 The alkyl group, Z being F, Cl, Br, or I, a being an integer from 1 to 3, and b being an integer from 1 to 4. Preferably, the titanium source is any one or more of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, tributoxytitanium chloride, dibutoxytitanium dichloride, butoxytitanium trichloride, triethoxytitanium chloride, diethoxytitanium dichloride, ethoxytitanium trichloride, and titanium trichloride; for example, titanium tetrachloride.

[0038] In the catalyst described in this invention, the alkylaluminum compound can be any of the various alkylaluminum compounds conventionally used in the art; for example, the general formula of the alkylaluminum compound can be AlR. 16R 16 'R 16 ′′, where R 16 R 16 ′ and R 16 Each of the alkyl groups is independently a C1-C8 alkyl group, and one or both groups can be halogens, and the hydrogen on the alkyl group can also be replaced by a halogen; specific examples of the C1-C8 alkyl groups may include, but are not limited to: methyl, ethyl, propyl, n-butyl, isobutyl, pentyl, hexyl, n-heptyl, n-octyl, and the halogen may be fluorine, chlorine, bromine, or iodine. Specifically, the alkylaluminum compound may be selected, for example, from any one or more of triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, diethylaluminum chloride, diisobutylaluminum chloride, di-n-butylaluminum chloride, di-n-hexylaluminum chloride, diethylaluminum chloride, diisobutylaluminum chloride, di-n-butylaluminum chloride, and di-n-hexylaluminum chloride; for example, triethylaluminum.

[0039] In the catalyst described in this invention, the external electron donor can be any of the external electron donors commonly used in the art. For example, the external electron donor can be selected from at least one of carboxylic acids, carboxylic anhydrides, carboxylic esters, ketones, ethers, alcohols, lactones, organophosphorus compounds, and organosilicon compounds. Preferably, the external electron donor contains at least one Si-OR bond and has the general formula (R 17 ) x (R 18 ) y Si(OR 19 ) z Silicon compounds, wherein R 17 R 18 and R 19 For C1-C 18 The hydrocarbon group, optionally containing heteroatoms, has x and y each being an independent integer from 0 to 2, z being an integer from 1 to 3, and the sum of x, y, and z is 4. Preferably, R 17 R 18 For C3-C 10 Alkyl or cycloalkyl groups, optionally containing heteroatoms; R 19 For C1-C 10 The alkyl group optionally contains heteroatoms. Specifically, the external electron donor may be selected, for example, from at least one of cyclohexylmethyldimethoxysilane, diisopropyldimethoxysilane, di-n-butyldimethoxysilane, diisobutyldimethoxysilane, diphenyldimethoxysilane, methyl tert-butyldimethoxysilane, dicyclopentyldimethoxysilane, 2-ethylpiperidinyl-2-tert-butyldimethoxysilane, (1,1,1-trifluoro-2-propyl)-2-ethylpiperidinyldimethoxysilane, and (1,1,1-trifluoro-2-propyl)-methyldimethoxysilane; for example, cyclohexylmethyldimethoxysilane.

[0040] According to some embodiments of the present invention, in the catalyst of the present invention, the molar ratio of the catalyst component based on titanium and the alkylaluminum compound based on aluminum can be 1:20 to 1000, preferably 1:30 to 300, for example 1:220.

[0041] According to some embodiments of the present invention, in the catalyst of the present invention, the molar ratio of the external electron donor to the alkylaluminum compound (calculated as aluminum) can be 1:2 to 300, preferably 1:5 to 100, for example 1:30.

[0042] The third aspect of the present invention provides the application of the above-mentioned plasticizer-free polypropylene with ultra-high melt flow rate or the above-mentioned plasticizer-free polypropylene with ultra-high melt flow rate prepared by the above-mentioned preparation method in the preparation of meltblown fabric.

[0043] Beneficial effects:

[0044] The present invention provides a method for preparing polypropylene with ultra-high melt flow rate without plasticizer, which does not use peroxide degradation and is obtained by direct polymerization during the polymerization process. This overcomes the problem that chemical degradation is required when preparing polypropylene resin for meltblown production in the prior art. The method uses direct hydrogen conditioning to prepare polypropylene with ultra-high melt flow rate without plasticizer. This polypropylene with ultra-high melt flow rate without plasticizer has the characteristics of being free of plasticizer and having low xylene soluble content.

[0045] The nonwoven fabric made of polypropylene with ultra-high melt flow rate and no plasticizer provided by the present invention has the characteristics of low resistance and high filtration efficiency.

[0046] The polypropylene with ultra-high melt flow rate that does not contain plasticizers provided by this invention does not use metallocene catalysts such as methylaluminoxane, which are expensive and have high requirements for production process control, as co-catalysts during the preparation process. It has the characteristics of low cost, easy production and stable supply. Attached Figure Description

[0047] Figure 1 The DSC curve of a polypropylene with ultra-high melt flow rate that does not contain plasticizer prepared in Example 1 of the present invention is shown. Detailed Implementation

[0048] The present invention will be further described below with reference to embodiments. However, the present invention is not limited to these embodiments.

[0049] In this invention, the melt flow rate (MFR) of polypropylene with ultra-high melt flow rate that does not contain plasticizer is tested according to GB / T3682-2000. Furthermore, in this invention, the XRZ-00 melt flow indexer manufactured by Changchun Xinke Experimental Instrument Equipment Co., Ltd. is used for testing.

[0050] The xylene-soluble content of polypropylene with ultra-high melt flow rate that does not contain plasticizers in this invention is tested according to GB / T24282-2009.

[0051] The relative molecular mass and distribution of polypropylene with ultra-high melt flow rate without plasticizer in this invention were tested using a PL-GPC220 gel permeation chromatograph manufactured by Polymer Laboratories, UK. Trichlorobenzene was used as the solvent, the test temperature was 150℃, polystyrene was used as the standard, the flow rate was 1.0 mL / min, and a 3×Plgel10mMlXED-B300×7.5nm column was used.

[0052] In this invention, when the melting point of the plasticizer-free polypropylene with ultra-high melt flow rate is tested using differential scanning calorimetry (DSC), the melting peak of the plasticizer-free polypropylene with ultra-high melt flow rate can be observed from the DSC curve. Specifically, a PE diamond DSC differential scanning calorimeter can be used, with a sample amount of 4-5 mg. The specific steps are as follows: first, heat the sample to 200°C at a rate of 10°C / min and hold for 5 min to eliminate thermal history; then, cool it to 50°C at a rate of 10°C / min and hold at 50°C for 1 min; then, heat it again to 200°C at a rate of 10°C / min. The melting temperature and melting enthalpy are determined from the DSC curve recorded after the reheating, and the melting peak and peak value are observed.

[0053] Example 1

[0054] This embodiment provides a plasticizer-free polypropylene with an ultra-high melt flow rate. The preparation method of this plasticizer-free polypropylene with an ultra-high melt flow rate is as follows:

[0055] (1) Preparation of catalyst component: 820 mmol of titanium tetrachloride was added to a 300 ml glass reaction flask and cooled to -20 °C. 37 mmol of magnesium halide support (prepared according to the method disclosed in Example 1 of CN1330086A) based on magnesium element was added to it. Then the temperature was raised to 110 °C. During the heating process, 0.5 mmol of tributyl phosphate and 7 mmol of 2-isopropyl-2-isopentyl-1,3-dimethoxypropane were added. After maintaining the temperature at 110 °C for 30 min, the liquid was filtered off. The mixture was washed twice with titanium tetrachloride (700 mmol of titanium tetrachloride each time) and five times with hexane. After vacuum drying, the catalyst component Cat-1 with ultra-high melt flow rate for polypropylene polymerization without plasticizer was obtained.

[0056] In the above, the molar ratio of magnesium source (calculated as magnesium element), titanium source (calculated as titanium element), and internal electron donor is 1:60:0.2.

[0057] (2) Preparation of polypropylene with ultra-high melt flow rate without plasticizer: The catalyst components Cat-1, triethylaluminum and cyclohexylmethyldimethoxysilane prepared above were pre-contaminated at a temperature of 10°C, and the mixture was added to a prepolymerization reactor for prepolymerization reaction. The prepolymerization reaction was carried out in a propylene liquid phase bulk environment at a prepolymerization temperature of 18°C. The resulting mixture was then continuously introduced into a loop reactor for propylene polymerization reaction at a polymerization temperature of 69°C and a reaction pressure of 3.9 MPa. Hydrogen gas was introduced into the feed of the loop reactor at a concentration of 10,000 ppm and a reaction time of 1 h. After polymerization, the mixture was flashed and steamed, then cooled, depressurized, and discharged. The resulting polypropylene with ultra-high melt flow rate without plasticizer was dried, weighed, and analyzed. The results are shown in Table 1.

[0058] In the above, the molar ratio of catalyst component Cat-1 (calculated as titanium) to triethylaluminum (calculated as aluminum) is 1:220; the molar ratio of cyclohexylmethyldimethoxysilane to triethylaluminum (calculated as aluminum) is 1:30; and the concentration of hydrogen is detected by online chromatography.

[0059] See the attached DSC test results. Figure 1 On the DSC curve after heating, cooling and then heating again, there is a distinct melting peak in the range of 150℃ to 159℃, with a peak value of 157.3℃, and another distinct melting peak in the range of 160℃ to 170℃, with a peak value of 164.5℃.

[0060] Example 2

[0061] This embodiment provides a plasticizer-free polypropylene with an ultra-high melt flow rate. The plasticizer-free polypropylene with an ultra-high melt flow rate is prepared according to the method of Example 1, except that the amount of hydrogen added during the polymerization reaction is 13000ppm. The obtained plasticizer-free polypropylene with an ultra-high melt flow rate is dried, weighed and analyzed. The results are shown in Table 1.

[0062] The DSC test results show that, after heating and cooling, and then heating again, there is a distinct melting peak in the range of 150℃ to 159℃, with a peak value of 155.8℃; and another distinct melting peak in the range of 160℃ to 170℃, with a peak value of 163.9℃.

[0063] Example 3

[0064] This embodiment provides a plasticizer-free polypropylene with an ultra-high melt flow rate. The plasticizer-free polypropylene with an ultra-high melt flow rate is prepared according to the method of Example 1, except that the amount of hydrogen added during the polymerization reaction is 11000ppm. The obtained plasticizer-free polypropylene with an ultra-high melt flow rate is dried, weighed and analyzed. The results are shown in Table 1.

[0065] The DSC test results show that, after heating and cooling, and then heating again, there is a distinct melting peak in the range of 150℃ to 159℃, with a peak value of 157.1℃; and another distinct melting peak in the range of 160℃ to 170℃, with a peak value of 164.1℃.

[0066] Table 1. Detection results of polypropylene with ultra-high melt flow rate without plasticizer prepared in Examples 1-3 of this invention.

[0067]

[0068] Comparative Example

[0069] On a 1.6m wide meltblown fabric production line, meltblown nonwoven fabrics were prepared using polypropylene with ultra-high melt flow rate and no plasticizer prepared in Examples 1-3 of this invention and commercially available meltblown polypropylene with an MFR of 1500g / 10min prepared by degradation method. The prepared meltblown nonwoven fabrics were subjected to performance tests, and the test results are shown in Table 2.

[0070] Table 2 shows the performance test results of meltblown nonwoven fabrics prepared from plasticizer-free polypropylene with ultra-high melt flow rate prepared in Examples 1-3 of this invention and commercially available meltblown polypropylene prepared by degradation method with an MFR of 1500 g / 10 min.

[0071]

[0072] As can be seen from the results in Tables 1 and 2 above, the polypropylene with ultra-high melt flow rate prepared by the method of the present invention (which does not contain plasticizers) has an ultra-high melt flow rate, low xylene soluble content, and a wide molecular weight distribution. Furthermore, the melt curve obtained by DSC testing shows at least two peaks. Secondly, the polypropylene with ultra-high melt flow rate prepared by the present invention does not contain phthalate plasticizers and does not require the addition of peroxides for degradation. It can be directly used to prepare meltblown nonwoven fabric. Compared with commercially available meltblown nonwoven fabric prepared by degradation methods, the prepared meltblown nonwoven fabric maintains high filtration efficiency while exhibiting lower resistance.

[0073] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A polypropylene with ultra-high melt flow rate that does not contain plasticizers, characterized in that, The plasticizer-free polypropylene with ultra-high melt flow rate has a melt flow rate greater than 1500 g / 10 min at a temperature of 230°C and a pressure of 2.16 kg, and a xylene-soluble content of less than 4 wt%. When the polypropylene without plasticizer and with ultra-high melt flow rate was analyzed by differential scanning calorimetry, at least two melting peaks appeared on the DSC curve, one of which had a peak value of 150℃~159℃ and the other had a peak value of 160℃~170℃. The method for preparing the plasticizer-free polypropylene with ultra-high melt flow rate includes polymerizing propylene under olefin polymerization conditions in the presence of a catalyst and hydrogen to obtain the plasticizer-free polypropylene with ultra-high melt flow rate. During the polymerization process, the concentration of hydrogen gas is 8000ppm to 17000ppm; The catalyst comprises a catalyst component, an alkylaluminum compound, and an external electron donor; the catalyst component comprises a Ziegler-Natta catalyst without plasticizer.

2. The polypropylene with ultra-high melt flow rate and no plasticizer as described in claim 1, characterized in that, The molecular weight distribution index of the plasticizer-free polypropylene with ultra-high melt flow rate is between 4 and 7.

3. The polypropylene with ultra-high melt flow rate and no plasticizer as described in claim 2, characterized in that, The molecular weight distribution index of the plasticizer-free polypropylene with ultra-high melt flow rate is 4.5 to 6.

5.

4. The polypropylene with ultra-high melt flow rate that is free of plasticizer according to any one of claims 1-3, characterized in that, The plasticizer-free polypropylene with ultra-high melt flow rate has a melt flow rate of 1600g / 10min to 3500g / 10min under the conditions of 230℃ and 2.16kg pressure.

5. The polypropylene with ultra-high melt flow rate and no plasticizer according to claim 4, characterized in that, The plasticizer-free polypropylene with ultra-high melt flow rate has a melt flow rate of 1800g / 10min to 3000g / 10min under the conditions of 230℃ and 2.16kg pressure.

6. The method for preparing polypropylene with ultra-high melt flow rate without plasticizer according to any one of claims 1-5, characterized in that, The preparation method includes polymerizing propylene under olefin polymerization conditions in the presence of a catalyst and hydrogen to obtain the plasticizer-free polypropylene with an ultra-high melt flow rate. During the polymerization process, the concentration of hydrogen is 8000ppm to 17000ppm; The catalyst comprises a catalyst component, an alkylaluminum compound, and an external electron donor; the catalyst component comprises a Ziegler-Natta catalyst without plasticizer.

7. The preparation method according to claim 6, characterized in that, The preparation method includes a pre-contact reaction of the catalyst component, alkylaluminum compound, and external electron donor before the polymerization reaction; And / or, the preparation method further includes prepolymerizing the catalyst with propylene and / or other α-olefin monomers after the pre-contact reaction and before the polymerization reaction; And / or, the polymerization reaction is carried out under the protection of an inert gas, in a liquid monomer or an inert solvent containing the monomer, or in the gas phase, or by a combination of gas-liquid phase polymerization process conditions. And / or, the polymerization reaction is carried out at a temperature of 20°C to 150°C; And / or, the pressure of the polymerization reaction is 0.02 MPa to 10 MPa; And / or, the polymerization reaction takes 0.5 h to 6 h.

8. The preparation method according to claim 7, characterized in that, The pre-contact reaction temperature is -10℃ to 30℃; And / or, hydrogen may or may not be added during the prepolymerization reaction; And / or, the polymerization reaction is carried out at a temperature of 60°C to 90°C; And / or, the pressure of the polymerization reaction is 1 MPa to 6 MPa; And / or, the polymerization reaction takes 1 to 2 hours.

9. The preparation method according to claim 8, characterized in that, The pre-contact reaction temperature is 0℃~20℃; And / or, the prepolymerization reaction temperature is 10℃~50℃; And / or, the pressure of the polymerization reaction is 2 MPa to 5 MPa.

10. The preparation method according to claim 9, characterized in that, The pre-contact reaction temperature is 5℃~15℃; And / or, the prepolymerization reaction temperature is 15℃~30℃.

11. The preparation method according to claim 10, characterized in that, The prepolymerization reaction temperature is 17℃~20℃.

12. The preparation method according to any one of claims 6-11, characterized in that, The catalyst component is a reaction product containing the following components: (i) Magnesium-containing compounds; (ii) Titanium-containing compounds; And (iii) internal electron donors.

13. The preparation method according to claim 12, characterized in that, The internal electron donor is a complex of any one or more of the following non-plasticizer compounds: ethers, alcohol esters, diesters, monoesters, cyano esters, diketones, and diamines.

14. The preparation method according to claim 13, characterized in that, The internal electron donor is a 1,3-diether compound of formula (1): Equation (1); In equation (1), R Ⅰ R Ⅱ R Ⅲ R Ⅳ R Ⅴ and R Ⅵ Whether they are the same or different, they are each independently selected from hydrogen, halogen atoms, and C1-C atoms. 20 Straight-chain alkyl, C3-C 20 Branched alkyl groups, C3-C 20 cycloalkyl, C6-C 20 aryl, C7-C 20 Any one of the aryl alkyl groups, R Ⅶ and R Ⅷ Whether they are the same or different, each is independently selected from C1-C 20 Straight-chain alkyl, C3-C 20 Branched alkyl groups, C3-C 20 cycloalkyl, C6-C 20 aryl, C7-C 20 alkylaryl, C7-C 20 Any one of the aryl alkyl groups, R Ⅰ R Ⅱ R Ⅲ R Ⅳ R Ⅴ and R Ⅵ The groups are optionally linked together to form a ring.

15. The preparation method according to claim 14, characterized in that, The 1,3-diether compounds are selected from 2-(2-ethylhexyl)-1,3-dimethoxypropane, 2-isopropyl-1,3-dimethoxypropane, 2-butyl-1,3-dimethoxypropane, 2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-1,3-dimethoxypropane, 2-phenyl-1,3-dimethoxypropane, 2-(2-phenylethyl)-1,3-dimethoxypropane, 2-(2-cyclohexylethyl)-1,3-dimethoxypropane, 2-(p-chlorophenyl)-1,3-dimethoxypropane, 2-(diphenylmethyl)-1,3-dimethoxypropane, 2,2-dicyclohexyl-1,3-dimethoxypropane, 2 2-Dicyclopentyl-1,3-dimethoxypropane, 2,2-diethyl-1,3-dimethoxypropane, 2,2-dipropyl-1,3-dimethoxypropane, 2,2-diisopropyl-1,3-dimethoxypropane, 2,2-dibutyl-1,3-dimethoxypropane, 2-methyl-2-propyl-1,3-dimethoxypropane, 2-methyl-2-benzyl-1,3-dimethoxypropane, 2-methyl-2-ethyl-1,3-dimethoxypropane, 2-methyl-2-isopropyl-1,3-dimethoxypropane, 2-methyl-2-phenyl-1,3-dimethoxypropane, 2-methyl-2-cyclohexyl-1,3-dimethoxypropane, 2,2- Bis(2-cyclohexylethyl)-1,3-dimethoxypropane, 2-methyl-2-isobutyl-1,3-dimethoxypropane, 2-methyl-2-(2-ethylhexyl)-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane, 2,2-dibenzyl-1,3-dimethoxypropane, 2,2-bis(cyclohexylmethyl)-1,3-dimethoxypropane, 2-isobutyl-2-isopropyl-1,3-dimethoxypropane, 2-(1-methylbutyl)-2-isopropyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, At least one of 2-phenyl-2-isopropyl-1,3-dimethoxypropane, 2-phenyl-2-sec-butyl-1,3-dimethoxypropane, 2-benzyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclopentyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclopentyl-2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclohexyl-2-sec-butyl-1,3-dimethoxypropane, 2-isopropyl-2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-2-cyclohexylmethyl-1,3-dimethoxypropane, and 9,9-dimethoxymethylfluorene.

16. The preparation method according to claim 14, characterized in that, The internal electron donor also includes the phosphate ester compound shown in formula (2): （2） In equation (2), R 13 R 14 and R 15 Whether the same or different, each is independently selected from C1-C4 straight-chain alkyl, C3-C4 branched alkyl, C3-C 20 cycloalkyl, C6-C 20 aryl, C7-C 20 alkylaryl and C7-C 20 Any one of the aralkyl groups, optionally, the C6-C 20 aryl, C7-C 20 alkylaryl and C7-C 20 In aralkyl groups, the hydrogen atoms on the benzene ring are replaced by halogen atoms.

17. The preparation method according to claim 16, characterized in that, In equation (2), R 13 R 14 and R 15 Whether the same or different, each is independently selected from C1-C4 straight-chain alkyl, C3-C4 branched alkyl, C3-C 12 cycloalkyl, C6-C 12 aryl, C7-C 12 alkylaryl and C7-C 12 Any one of the aryl, alkylaryl and aryl groups, wherein the hydrogen atoms on the benzene ring in the aryl, alkylaryl and aryl groups are optionally replaced by halogen atoms.

18. The preparation method according to claim 17, characterized in that, In equation (2), R 13 R 14 and R 15 They may be the same or different, each independently selected from any one of C1-C4 straight-chain alkyl, C3-C4 branched alkyl, C3-C6 cycloalkyl, C6-C8 aryl, C7-C8 alkylaryl, and C7-C8 aralkyl, wherein the hydrogen atoms on the benzene ring in the aryl, alkylaryl, and aralkyl groups are optionally substituted with halogen atoms.

19. The preparation method according to claim 18, characterized in that, In equation (2), R 13 R 14 and R 15 They may be the same or different, each independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, phenyl, tolyl, dimethylphenyl, ethylphenyl, benzyl, methylbenzyl or phenethyl.

20. The preparation method according to claim 16, characterized in that, The phosphate ester compound is selected from at least one of trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, tricresyl phosphate, triisopropylphenyl phosphate, trimethoxyphenyl phosphate, dimethyl phosphate, toluene dibutyl phosphate, isopropylphenyl dimethyl phosphate, isopropylphenyl diethyl phosphate, isopropylphenyl dibutyl phosphate, phenylxyl phosphate, phenylxyl diisopropylphenyl phosphate, p-toluene dibutyl phosphate, m-toluene dibutyl phosphate, p-isopropylphenyl dimethyl phosphate, p-isopropylphenyl diethyl phosphate, p-tert-butylphenyl dimethyl phosphate, and o-toluene p-di-tert-butylphenyl phosphate.

21. The preparation method according to claim 16, characterized in that, The molar ratio of the phosphate ester compound to the 1,3-diether compound is 0.03~0.3:

1.

22. The preparation method according to claim 7, characterized in that, In the catalyst, the molar ratio of the catalyst component (calculated as titanium) to the alkylaluminum compound (calculated as aluminum) is 1:20~1000. And / or, the molar ratio of the external electron donor to the alkylaluminum compound, calculated in terms of aluminum, is 1:2 to 300.

23. The preparation method according to claim 22, characterized in that, In the catalyst, the molar ratio of the catalyst component (calculated as titanium) to the alkylaluminum compound (calculated as aluminum) is 1:30~300. And / or, the molar ratio of the external electron donor to the alkylaluminum compound, calculated in terms of aluminum, is 1:5 to 100.

24. The application of a plasticizer-free polypropylene with ultra-high melt flow rate according to any one of claims 1-5 or a plasticizer-free polypropylene with ultra-high melt flow rate prepared by any one of claims 6-23 in the preparation of meltblown fabric.

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