Heat-resistant high-molecular polypropylene filter material and preparation method thereof

Abstract

The invention discloses a heat-resistant high-molecular-weight polypropylene filter material and a preparation method thereof, and particularly relates to the technical field of high-molecular-weight materials, and relates to a heat-resistant high-molecular-weight polypropylene filter material and a preparation method thereof. The heat-resistant high-molecular-weight polypropylene filter material is prepared from an inorganic filler, a polypropylene resin, 4-methyl-1-pentene, an antioxidant, calcium stearate, dicumyl peroxide, and 4-vinyl benzoic acid glycidyl ester. The components and weight proportions of the raw materials for preparation are as follows: 0.8-1.5 parts of the inorganic filler, 65-85 parts of the polypropylene resin, 6-10 parts of 4-methyl-1-pentene, 0.1-0.3 parts of the antioxidant, 0.1-0.3 parts of the calcium stearate, 0.2-0.6 parts of dicumyl peroxide, and 1-5 parts of 4-vinyl benzoic acid glycidyl ester. The invention is constructed by a preparation process of mixing melt-blown fibers and electrospun fibers, thereby providing sufficient mechanical strength and stability for the entire filter material, efficiently intercepting tiny particles, improving filtration accuracy, and achieving a smooth transition between fibers of different sizes.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and more particularly to a heat-resistant polymer polypropylene filter material and a preparation method thereof. Background Art

[0002] Filter materials are widely used in many fields such as chemical industry, food, medicine, and environmental protection. Polypropylene has good chemical stability, mechanical properties and processing properties, and is widely used in the field of filter materials, becoming a commonly used filter material matrix. Therefore, the development of a new polypropylene filter material with excellent performance has important practical significance.

[0003] Polypropylene in related technologies includes propylene monomer, catalyst and additives; among them, propylene monomer is the basic raw material, which is connected through polymerization reaction to form long-chain polypropylene macromolecules, which directly determines the chemical structure and basic properties of polypropylene and is the cornerstone of polypropylene materials; the catalyst is usually a Ziegler-Natta catalyst, whose function is to reduce the activation energy of the polymerization reaction, greatly accelerate the polymerization rate of propylene monomer, and enable the reaction to proceed under relatively mild conditions; it can accurately control the regularity of the polypropylene molecular chain, thereby affecting the key properties of polypropylene such as crystallization performance, melting point, and strength; additives include molecular weight regulators, antioxidants, and lubricants, which affect the mechanical properties of polypropylene.

[0004] However, it still has some shortcomings in actual use, such as poor heat resistance. The deformation temperature of polypropylene in related technologies is low. Under high temperature environment, the movement of molecular chain segments is intensified, and it is easy to soften, deform or even melt, resulting in poor shape and dimensional stability of the material; poor mechanical properties. High temperature will significantly weaken the mechanical properties of traditional polypropylene. Its mechanical indicators such as tensile strength and bending strength will drop significantly under high temperature, making it easy to break and damage when subjected to certain external forces; low filtration efficiency. The surface and internal structure of traditional polypropylene are easily corroded in complex environments such as high temperature, high humidity and chemical media, resulting in changes in the filtration pore size, reduced filtration efficiency and difficulty in maintaining stability for a long time. Summary of the Invention

[0005] In order to improve the above problems and reduce the problems of poor heat resistance, poor mechanical properties and low filtration efficiency of heat-resistant polymer polypropylene filter materials in the related art, the present invention specially provides a heat-resistant polymer polypropylene filter material and a preparation method thereof to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A heat-resistant high-molecular polypropylene filter material comprises the following steps:

[0008] A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix for 10-20 minutes at a temperature of 60-80° C. and a rotation speed of 800-1200 r / min to obtain a mixed raw material;

[0009] A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: 180-190° C. in zone 1, 190-200° C. in zone 2, 200-210° C. in zone 3, 210-220° C. in zone 4, and 220-230° C. in the die. The screw speed was controlled at 180-220 r / min and the feed rate was 20-30 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch.

[0010] A3, the modified polypropylene masterbatch obtained in A2 and dicumyl peroxide were mixed in a low-speed mixer at a temperature of 40-50° C. and a rotation speed of 30-50 r / min for 10-15 min to obtain a mixed masterbatch;

[0011] A4, the mixed masterbatch obtained in A3 was added to the melt-blowing equipment, the melt-blowing die temperature was set to 230-240 ° C, the hot air temperature was set to 250-260 ° C, the hot air pressure was set to 0.2-0.3 MPa, the receiving distance was set to 15 cm, and the melt-blown fiber layer was prepared to 0.2 mm; then the mixed masterbatch was dissolved in the mixed solvent to prepare a solution with a mass fraction of 10%, and then the solution was loaded into the electrospinning device, the voltage was set to 18-22 kV, the propulsion rate was set to 0.5-1.0 mL / h, the receiving distance was set to 15 cm, and the melt-blown fiber layer was prepared. 300mm electrospun fiber layer; during the process, the relative positions of the electrospinning nozzle and the meltblowing die head were adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then, the meltblowing hot air pressure was reduced at a rate of 0.002MPa / min, the meltblowing die head temperature was increased at a rate of 0.2℃ / min, the electrospinning propulsion rate was increased at a rate of 0.01mL / min, and the voltage was reduced at a rate of 0.1kV / min for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5kV / m was applied to obtain a filter material;

[0012] A5, using wavelength 2-5um, power density 3W / cm 2 The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145° C., and then dried in an oven at a temperature of 180-200° C. for 30-60 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

[0013] Preferably, the components and weight proportions of the raw materials for preparing the heat-resistant polymer polypropylene filter material are as follows: 0.8-1.5 parts of inorganic filler, 65-85 parts of polypropylene resin, 6-10 parts of 4-methyl-1-pentene, 0.1-0.3 parts of antioxidant, 0.1-0.3 parts of calcium stearate, 0.2-0.6 parts of dicumyl peroxide, and 1-5 parts of 4-vinyl benzoic acid glycidyl ester.

[0014] Preferably, the inorganic filler is prepared from silane coupling agent KH-570 and boron nitride powder.

[0015] Preferably, the inorganic filler comprises the following preparation steps:

[0016] C1. Place silane coupling agent KH-570 in 10-20 times the volume of anhydrous ethanol, and then use a stirrer at a speed of 200-300 rpm to stir for 10-15 minutes to obtain a silane coupling agent solution;

[0017] C2. Place the boron nitride powder in an oven, dry it at 100-120° C. for 2-3 hours, cool it to room temperature, and then transfer it to a high-speed mixer. Then, start the high-speed mixer and adjust the speed to 500-800 r / min. Use a dropper to add the silane coupling agent solution obtained in C1 dropwise to the mixer at a dropping speed of 2 drops / s. After the addition is complete, continue stirring at 80-100° C. for 30-60 minutes to obtain a mixed product.

[0018] C3. Transfer the mixed product obtained in C2 to a vacuum drying oven, dry it at a temperature of 60-80°C for 6-8 hours, then place it in a ball mill, and ball mill it at a speed of 300 r / min for 3 hours. Then, select a 300-mesh sieve for sieving to obtain an inorganic filler.

[0019] Preferably, the raw material components and weight proportions of the inorganic filler are as follows: 0.5-5 parts of silane coupling agent KH-570 and 100 parts of boron nitride powder.

[0020] Preferably, the mixed solvent consists of xylene and tetrahydrofuran in a volume ratio of 3:1.

[0021] Preferably, the antioxidant is antioxidant 1010.

[0022] The technical effects and advantages of the present invention are as follows:

[0023] 1. The present invention uses 4-vinyl benzoic acid glycidyl ester and propylene to carry out copolymerization reaction, and introduces epoxy groups into the polypropylene molecular chain, which significantly improves the cross-linking ability of the material, improves its heat resistance and the regularity of the molecular chain;

[0024] 2. The present invention introduces surface-functionalized nano-inorganic fillers, which are evenly dispersed in the polypropylene matrix. Utilizing the high thermal conductivity and mechanical properties of boron nitride, the heat resistance and strength of the material are further enhanced, while also improving filtration performance.

[0025] 3. The present invention constructs a gradient structure through a special preparation process, mixing melt-blown fibers and electrospun fibers, which not only provides sufficient mechanical strength and stability for the entire filter material, but also can efficiently intercept tiny particles, improve filtration accuracy, and achieve a smooth transition between fibers of different sizes, ensuring both filtration efficiency and air permeability, so that the filter material has different pore sizes and fiber densities at different levels, achieving an optimized combination of filtration accuracy and air permeability. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the examples of the present invention. The raw materials used in the examples and embodiments of the present invention are all commercially available materials unless otherwise specified below.

[0027] Preparation Examples 1-5

[0028] An inorganic filler, the preparation components and their corresponding proportions are shown in the following table, and is prepared by the following preparation method:

[0029] C1. Place silane coupling agent KH-570 in 10 times the volume of anhydrous ethanol, and then use a stirrer to stir at a speed of 200 r / min for 10 minutes to obtain a silane coupling agent solution;

[0030] C2. Place the boron nitride powder in an oven, dry it at 100°C for 2 hours, cool it to room temperature, and then transfer it to a high-speed mixer. Then, start the high-speed mixer and adjust the speed to 500 r / min. Use a dropper to add the silane coupling agent solution obtained in C1 dropwise to the mixer at a dropping speed of 2 drops / s. After the addition is complete, continue stirring at 80°C for 30 minutes to obtain a mixed product.

[0031] C3. The mixed product obtained in C2 was transferred to a vacuum drying oven and dried at 60°C for 6 hours. Then, the mixed product was placed in a ball mill and ball-milled at a speed of 300 r / min for 3 hours. The mixed product was then sieved through a 300-mesh sieve to obtain an inorganic filler.

[0032] Table: Components and mass ratios of raw materials in Preparation Examples 1-5 (g)

[0033]

[0034]

[0035] Preparation Example 6

[0036] An inorganic filler, which is different from Preparation Example 1 in that the preparation method is as follows:

[0037] C1. Place silane coupling agent KH-570 in 10 times the volume of anhydrous ethanol, and then use a stirrer to stir at a speed of 250 r / min for 12.5 minutes to obtain a silane coupling agent solution;

[0038] C2. Place the boron nitride powder in an oven, dry it at 110°C for 2.5 hours, cool it to room temperature, and then transfer it to a high-speed mixer. Then, start the high-speed mixer and adjust the speed to 650 r / min. Use a dropper to add the silane coupling agent solution obtained in C1 dropwise to the mixer at a dropping speed of 2 drops / s. After the addition is complete, continue stirring at 90°C for 45 minutes to obtain a mixed product.

[0039] C3. The mixed product obtained in C2 was transferred to a vacuum drying oven and dried at 70°C for 7 hours. Then, the mixed product was placed in a ball mill and ball-milled at a speed of 300 r / min for 3 hours. The mixed product was then sieved through a 300-mesh sieve to obtain an inorganic filler.

[0040] Preparation Example 7

[0041] An inorganic filler, which is different from Preparation Example 1 in that the preparation method is as follows:

[0042] C1. Place silane coupling agent KH-570 in 10 times the volume of anhydrous ethanol, and then use a stirrer to stir at a speed of 300 r / min for 15 minutes to obtain a silane coupling agent solution;

[0043] C2. Place the boron nitride powder in an oven, dry it at 120° C. for 3 h, cool it to room temperature, and then transfer it to a high-speed mixer. Then, start the high-speed mixer and adjust the speed to 800 r / min. Use a dropper to add the silane coupling agent solution obtained in C1 dropwise to the mixer at a dropping speed of 2 drops / s. After the addition is complete, continue stirring at 100° C. for 60 min to obtain a mixed product.

[0044] C3. The mixed product obtained in C2 was transferred to a vacuum drying oven and dried at 80°C for 8 hours. Then, the mixed product was placed in a ball mill and ball-milled at a speed of 300 r / min for 3 hours. The mixed product was then sieved through a 300-mesh sieve to obtain an inorganic filler.

[0045] Preparation Example 8

[0046] An inorganic filler, which is different from Preparation Example 1 in that the preparation method is as follows:

[0047] C1. Place silane coupling agent KH-570 in 15 times the volume of anhydrous ethanol, and then use a stirrer to stir at a speed of 200 r / min for 10 minutes to obtain a silane coupling agent solution;

[0048] C2. Place the boron nitride powder in an oven, dry it at 100°C for 2 hours, cool it to room temperature, and then transfer it to a high-speed mixer. Then, start the high-speed mixer and adjust the speed to 500 r / min. Use a dropper to add the silane coupling agent solution obtained in C1 dropwise to the mixer at a dropping speed of 2 drops / s. After the addition is complete, continue stirring at 80°C for 30 minutes to obtain a mixed product.

[0049] C3. The mixed product obtained in C2 was transferred to a vacuum drying oven and dried at 60°C for 6 hours. Then, the mixed product was placed in a ball mill and ball-milled at a speed of 300 r / min for 3 hours. The mixed product was then sieved through a 300-mesh sieve to obtain an inorganic filler.

[0050] Preparation Example 9

[0051] An inorganic filler, which is different from Preparation Example 1 in that the preparation method is as follows:

[0052] C1. Place silane coupling agent KH-570 in 20 times the volume of anhydrous ethanol, and then use a stirrer to stir at a speed of 200 r / min for 10 minutes to obtain a silane coupling agent solution;

[0053] C2. Place the boron nitride powder in an oven, dry it at 100°C for 2 hours, cool it to room temperature, and then transfer it to a high-speed mixer. Then, start the high-speed mixer and adjust the speed to 500 r / min. Use a dropper to add the silane coupling agent solution obtained in C1 dropwise to the mixer at a dropping speed of 2 drops / s. After the addition is complete, continue stirring at 80°C for 30 minutes to obtain a mixed product.

[0054] C3. The mixed product obtained in C2 was transferred to a vacuum drying oven and dried at 60°C for 6 hours. Then, the mixed product was placed in a ball mill and ball-milled at a speed of 300 r / min for 3 hours. The mixed product was then sieved through a 300-mesh sieve to obtain an inorganic filler.

[0055] Preparation Examples 10-14

[0056] A heat-resistant high-molecular-weight polypropylene filter material, the components and their corresponding proportions of which are shown in the following table, is prepared using the following preparation method:

[0057] A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix at a temperature of 60° C. and a speed of 800 r / min for 10 min to obtain a mixed raw material;

[0058] The inorganic filler is prepared by Preparation Example 1;

[0059] The antioxidant is antioxidant 1010;

[0060] A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: 180°C in zone 1, 190°C in zone 2, 200°C in zone 3, 210°C in zone 4, and 220°C in the die. The screw speed was controlled at 180 r / min and the feed rate was 30 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch.

[0061] A3. Mix the modified polypropylene masterbatch obtained in A2 with dicumyl peroxide in a low-speed mixer at a temperature of 40° C. and a rotation speed of 30 r / min for 10 min to obtain a mixed masterbatch;

[0062] A4, the mixed masterbatch obtained in A3 was added to the meltblowing equipment, and the meltblowing die temperature, hot air temperature, hot air pressure and receiving distance were set to 230 ° C, 250 ° C, 0.2 MPa, and 15 cm, respectively, to prepare a meltblown fiber layer to 0.2 mm; the mixed masterbatch was then dissolved in a mixed solvent to prepare a solution with a mass fraction of 10%, and the solution was then loaded into an electrospinning device, and the voltage was set to 18 kV, the propulsion rate was 1.0 mL / h, and the receiving distance was 15 cm to prepare a 300 mm electrospun fiber layer; during this period, the relative position of the electrospinning nozzle and the meltblowing die was adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then, the meltblowing hot air pressure was reduced by 0.002 MPa / min, the meltblowing die temperature was increased by 0.2 ° C / min, the electrospinning propulsion rate was increased by 0.01 mL / min, and the voltage was reduced by 0.1 kV / min. The conditions were adjusted for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5 kV / m was applied to obtain a filter material;

[0063] The mixed solvent is composed of xylene and tetrahydrofuran in a volume ratio of 3:1;

[0064] A5, using wavelength 2um, power density 3W / cm 2 The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145°C, and then dried in an oven at a temperature of 180°C for 30 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

[0065] Table: Components and mass ratios of raw materials in Preparation Examples 10-14 (kg)

[0066]

[0067] Preparation Example 15

[0068] A heat-resistant high-molecular polypropylene filter material, which differs from Preparation Example 10 in that the preparation method is as follows:

[0069] A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix at a temperature of 70° C. and a rotation speed of 1000 r / min for 15 min to obtain a mixed raw material;

[0070] A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: 180°C in zone 1, 190°C in zone 2, 200°C in zone 3, 210°C in zone 4, and 220°C in the die. The screw speed was controlled at 180 r / min and the feed rate was 30 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch.

[0071] A3. Mix the modified polypropylene masterbatch obtained in A2 with dicumyl peroxide in a low-speed mixer at a temperature of 40° C. and a rotation speed of 30 r / min for 10 min to obtain a mixed masterbatch;

[0072] A4, the mixed masterbatch obtained in A3 was added to the meltblowing equipment, and the meltblowing die temperature, hot air temperature, hot air pressure and receiving distance were set to 230 ° C, 250 ° C, 0.2 MPa, and 15 cm, respectively, to prepare a meltblown fiber layer to 0.2 mm; the mixed masterbatch was then dissolved in a mixed solvent to prepare a solution with a mass fraction of 10%, and the solution was then loaded into an electrospinning device, and the voltage was set to 18 kV, the propulsion rate was 1.0 mL / h, and the receiving distance was 15 cm to prepare a 300 mm electrospun fiber layer; during this period, the relative position of the electrospinning nozzle and the meltblowing die was adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then, the meltblowing hot air pressure was reduced by 0.002 MPa / min, the meltblowing die temperature was increased by 0.2 ° C / min, the electrospinning propulsion rate was increased by 0.01 mL / min, and the voltage was reduced by 0.1 kV / min. The conditions were adjusted for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5 kV / m was applied to obtain a filter material;

[0073] A5, using wavelength 2um, power density 3W / cm 2The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145°C, and then dried in an oven at a temperature of 180°C for 30 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

[0074] Preparation Example 16

[0075] A heat-resistant high-molecular polypropylene filter material, which differs from Preparation Example 10 in that the preparation method is as follows:

[0076] A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix at a temperature of 80° C. and a rotation speed of 1200 r / min for 20 min to obtain a mixed raw material;

[0077] A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: 180°C in zone 1, 190°C in zone 2, 200°C in zone 3, 210°C in zone 4, and 220°C in the die. The screw speed was controlled at 180 r / min and the feed rate was 30 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch.

[0078] A3. Mix the modified polypropylene masterbatch obtained in A2 with dicumyl peroxide in a low-speed mixer at a temperature of 40° C. and a rotation speed of 30 r / min for 10 min to obtain a mixed masterbatch;

[0079] A4, the mixed masterbatch obtained in A3 was added to the meltblowing equipment, and the meltblowing die temperature, hot air temperature, hot air pressure and receiving distance were set to 230 ° C, 250 ° C, 0.2 MPa, and 15 cm, respectively, to prepare a meltblown fiber layer to 0.2 mm; the mixed masterbatch was then dissolved in a mixed solvent to prepare a solution with a mass fraction of 10%, and the solution was then loaded into an electrospinning device, and the voltage was set to 18 kV, the propulsion rate was 1.0 mL / h, and the receiving distance was 15 cm to prepare a 300 mm electrospun fiber layer; during this period, the relative position of the electrospinning nozzle and the meltblowing die was adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then, the meltblowing hot air pressure was reduced by 0.002 MPa / min, the meltblowing die temperature was increased by 0.2 ° C / min, the electrospinning propulsion rate was increased by 0.01 mL / min, and the voltage was reduced by 0.1 kV / min. The conditions were adjusted for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5 kV / m was applied to obtain a filter material;

[0080] A5, using wavelength 2um, power density 3W / cm 2The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145°C, and then dried in an oven at a temperature of 180°C for 30 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

[0081] Preparation Example 17

[0082] A heat-resistant high-molecular polypropylene filter material, which differs from Preparation Example 10 in that the preparation method is as follows:

[0083] A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix at a temperature of 60° C. and a speed of 800 r / min for 10 min to obtain a mixed raw material;

[0084] A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: zone 1 185°C, zone 2 195°C, zone 3 205°C, zone 4 215°C, and die head 225°C. The screw speed was controlled at 200 r / min and the feed rate was 25 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch.

[0085] A3. Mix the modified polypropylene masterbatch obtained in A2 with dicumyl peroxide in a low-speed mixer at a temperature of 40° C. and a rotation speed of 30 r / min for 10 min to obtain a mixed masterbatch;

[0086] A4, the mixed masterbatch obtained in A3 was added to the meltblowing equipment, and the meltblowing die temperature, hot air temperature, hot air pressure and receiving distance were set to 230 ° C, 250 ° C, 0.2 MPa, and 15 cm, respectively, to prepare a meltblown fiber layer to 0.2 mm; the mixed masterbatch was then dissolved in a mixed solvent to prepare a solution with a mass fraction of 10%, and the solution was then loaded into an electrospinning device, and the voltage was set to 18 kV, the propulsion rate was 1.0 mL / h, and the receiving distance was 15 cm to prepare a 300 mm electrospun fiber layer; during this period, the relative position of the electrospinning nozzle and the meltblowing die was adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then, the meltblowing hot air pressure was reduced by 0.002 MPa / min, the meltblowing die temperature was increased by 0.2 ° C / min, the electrospinning propulsion rate was increased by 0.01 mL / min, and the voltage was reduced by 0.1 kV / min. The conditions were adjusted for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5 kV / m was applied to obtain a filter material;

[0087] A5, using wavelength 2um, power density 3W / cm 2The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145°C, and then dried in an oven at a temperature of 180°C for 30 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

[0088] Preparation Example 18

[0089] A heat-resistant high-molecular polypropylene filter material, which differs from Preparation Example 10 in that the preparation method is as follows:

[0090] A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix at a temperature of 60° C. and a speed of 800 r / min for 10 min to obtain a mixed raw material;

[0091] A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: 190°C in zone 1, 200°C in zone 2, 210°C in zone 3, 220°C in zone 4, and 230°C in the die. The screw speed was controlled at 220 r / min and the feed rate was 20 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch.

[0092] A3. Mix the modified polypropylene masterbatch obtained in A2 with dicumyl peroxide in a low-speed mixer at a temperature of 40° C. and a rotation speed of 30 r / min for 10 min to obtain a mixed masterbatch;

[0093] A4, the mixed masterbatch obtained in A3 was added to the meltblowing equipment, and the meltblowing die temperature, hot air temperature, hot air pressure and receiving distance were set to 230 ° C, 250 ° C, 0.2 MPa, and 15 cm, respectively, to prepare a meltblown fiber layer to 0.2 mm; the mixed masterbatch was then dissolved in a mixed solvent to prepare a solution with a mass fraction of 10%, and the solution was then loaded into an electrospinning device, and the voltage was set to 18 kV, the propulsion rate was 1.0 mL / h, and the receiving distance was 15 cm to prepare a 300 mm electrospun fiber layer; during this period, the relative position of the electrospinning nozzle and the meltblowing die was adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then, the meltblowing hot air pressure was reduced by 0.002 MPa / min, the meltblowing die temperature was increased by 0.2 ° C / min, the electrospinning propulsion rate was increased by 0.01 mL / min, and the voltage was reduced by 0.1 kV / min. The conditions were adjusted for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5 kV / m was applied to obtain a filter material;

[0094] A5, using wavelength 2um, power density 3W / cm 2The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145°C, and then dried in an oven at a temperature of 180°C for 30 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

[0095] Preparation Example 19

[0096] A heat-resistant high-molecular polypropylene filter material, which differs from Preparation Example 10 in that the preparation method is as follows:

[0097] A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix at a temperature of 60° C. and a speed of 800 r / min for 10 min to obtain a mixed raw material;

[0098] A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: 180°C in zone 1, 190°C in zone 2, 200°C in zone 3, 210°C in zone 4, and 220°C in the die. The screw speed was controlled at 180 r / min and the feed rate was 30 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch.

[0099] A3. Mix the modified polypropylene masterbatch obtained in A2 with dicumyl peroxide in a low-speed mixer at a temperature of 45° C. and a rotation speed of 40 r / min for 15 min to obtain a mixed masterbatch;

[0100] A4, the mixed masterbatch obtained in A3 was added to the meltblowing equipment, and the meltblowing die temperature, hot air temperature, hot air pressure and receiving distance were set to 230 ° C, 250 ° C, 0.2 MPa, and 15 cm, respectively, to prepare a meltblown fiber layer to 0.2 mm; the mixed masterbatch was then dissolved in a mixed solvent to prepare a solution with a mass fraction of 10%, and the solution was then loaded into an electrospinning device, and the voltage was set to 18 kV, the propulsion rate was 1.0 mL / h, and the receiving distance was 15 cm to prepare a 300 mm electrospun fiber layer; during this period, the relative position of the electrospinning nozzle and the meltblowing die was adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then, the meltblowing hot air pressure was reduced by 0.002 MPa / min, the meltblowing die temperature was increased by 0.2 ° C / min, the electrospinning propulsion rate was increased by 0.01 mL / min, and the voltage was reduced by 0.1 kV / min. The conditions were adjusted for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5 kV / m was applied to obtain a filter material;

[0101] A5, using wavelength 2um, power density 3W / cm 2The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145°C, and then dried in an oven at a temperature of 180°C for 30 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

[0102] Preparation Example 20

[0103] A heat-resistant high-molecular polypropylene filter material, which differs from Preparation Example 10 in that the preparation method is as follows:

[0104] A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix at a temperature of 60° C. and a speed of 800 r / min for 10 min to obtain a mixed raw material;

[0105] A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: 180°C in zone 1, 190°C in zone 2, 200°C in zone 3, 210°C in zone 4, and 220°C in the die. The screw speed was controlled at 180 r / min and the feed rate was 30 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch.

[0106] A3. Mix the modified polypropylene masterbatch obtained in A2 with dicumyl peroxide in a low-speed mixer at a temperature of 50° C. and a rotation speed of 50 r / min for 15 min to obtain a mixed masterbatch;

[0107] A4, the mixed masterbatch obtained in A3 was added to the meltblowing equipment, and the meltblowing die temperature, hot air temperature, hot air pressure and receiving distance were set to 230 ° C, 250 ° C, 0.2 MPa, and 15 cm, respectively, to prepare a meltblown fiber layer to 0.2 mm; the mixed masterbatch was then dissolved in a mixed solvent to prepare a solution with a mass fraction of 10%, and the solution was then loaded into an electrospinning device, and the voltage was set to 18 kV, the propulsion rate was 1.0 mL / h, and the receiving distance was 15 cm to prepare a 300 mm electrospun fiber layer; during this period, the relative position of the electrospinning nozzle and the meltblowing die was adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then, the meltblowing hot air pressure was reduced by 0.002 MPa / min, the meltblowing die temperature was increased by 0.2 ° C / min, the electrospinning propulsion rate was increased by 0.01 mL / min, and the voltage was reduced by 0.1 kV / min. The conditions were adjusted for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5 kV / m was applied to obtain a filter material;

[0108] A5, using wavelength 2um, power density 3W / cm 2The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145°C, and then dried in an oven at a temperature of 180°C for 30 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

[0109] Preparation Example 21

[0110] A heat-resistant high-molecular polypropylene filter material, which differs from Preparation Example 10 in that the preparation method is as follows:

[0111] A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix at a temperature of 60° C. and a speed of 800 r / min for 10 min to obtain a mixed raw material;

[0112] A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: 180°C in zone 1, 190°C in zone 2, 200°C in zone 3, 210°C in zone 4, and 220°C in the die. The screw speed was controlled at 180 r / min and the feed rate was 30 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch.

[0113] A3. Mix the modified polypropylene masterbatch obtained in A2 with dicumyl peroxide in a low-speed mixer at a temperature of 40° C. and a rotation speed of 30 r / min for 10 min to obtain a mixed masterbatch;

[0114] A4, the mixed masterbatch obtained in A3 was added to the meltblowing equipment, and the meltblowing die temperature, hot air temperature, hot air pressure and receiving distance were set to 235 ° C., 255 ° C., 0.25 MPa, and 15 cm. The meltblown fiber layer was prepared to 0.2 mm; the mixed masterbatch was then dissolved in a mixed solvent to prepare a solution with a mass fraction of 10%, and the solution was then loaded into an electrospinning device. The voltage was set to 20 kV, the propulsion rate was 0.75 mL / h, and the receiving distance was 15 cm to prepare a 300 mm electrospun fiber layer; during this period, the relative position of the electrospinning nozzle and the meltblowing die was adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then the meltblowing hot air pressure was reduced by 0.002 MPa / min, the meltblowing die temperature was increased by 0.2 ° C / min, the electrospinning propulsion rate was increased by 0.01 mL / min, and the voltage was reduced by 0.1 kV / min. The conditions were adjusted for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5 kV / m was applied to obtain a filter material;

[0115] A5, using wavelength 2um, power density 3W / cm 2The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145°C, and then dried in an oven at a temperature of 180°C for 30 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

[0116] Preparation Example 22

[0117] A heat-resistant high-molecular polypropylene filter material, which differs from Preparation Example 10 in that the preparation method is as follows:

[0118] A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix at a temperature of 60° C. and a speed of 800 r / min for 10 min to obtain a mixed raw material;

[0119] A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: 180°C in zone 1, 190°C in zone 2, 200°C in zone 3, 210°C in zone 4, and 220°C in the die. The screw speed was controlled at 180 r / min and the feed rate was 30 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch.

[0120] A3. Mix the modified polypropylene masterbatch obtained in A2 with dicumyl peroxide in a low-speed mixer at a temperature of 40° C. and a rotation speed of 30 r / min for 10 min to obtain a mixed masterbatch;

[0121] A4, the mixed masterbatch obtained in A3 was added to the meltblowing equipment, and the meltblowing die temperature, hot air temperature, hot air pressure and receiving distance were set to 240 ° C, 260 ° C, 0.3 MPa, and 15 cm, respectively, to prepare a meltblown fiber layer to 0.2 mm; the mixed masterbatch was then dissolved in a mixed solvent to prepare a solution with a mass fraction of 10%, and the solution was then loaded into an electrospinning device, and the voltage was set to 22 kV, the propulsion rate was 0.5 mL / h, and the receiving distance was 15 cm to prepare a 300 mm electrospun fiber layer; during this period, the relative position of the electrospinning nozzle and the meltblowing die was adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then, the meltblowing hot air pressure was reduced by 0.002 MPa / min, the meltblowing die temperature was increased by 0.2 ° C / min, the electrospinning propulsion rate was increased by 0.01 mL / min, and the voltage was reduced by 0.1 kV / min. The conditions were adjusted for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5 kV / m was applied to obtain a filter material;

[0122] A5, using wavelength 2um, power density 3W / cm 2The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145°C, and then dried in an oven at a temperature of 180°C for 30 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

[0123] Preparation Example 23

[0124] A heat-resistant high-molecular polypropylene filter material, which differs from Preparation Example 10 in that the preparation method is as follows:

[0125] A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix at a temperature of 60° C. and a speed of 800 r / min for 10 min to obtain a mixed raw material;

[0126] A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: 180°C in zone 1, 190°C in zone 2, 200°C in zone 3, 210°C in zone 4, and 220°C in the die. The screw speed was controlled at 180 r / min and the feed rate was 30 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch.

[0127] A3. Mix the modified polypropylene masterbatch obtained in A2 with dicumyl peroxide in a low-speed mixer at a temperature of 40° C. and a rotation speed of 30 r / min for 10 min to obtain a mixed masterbatch;

[0128] A4, the mixed masterbatch obtained in A3 was added to the meltblowing equipment, and the meltblowing die temperature, hot air temperature, hot air pressure and receiving distance were set to 230 ° C, 250 ° C, 0.2 MPa, and 15 cm, respectively, to prepare a meltblown fiber layer to 0.2 mm; the mixed masterbatch was then dissolved in a mixed solvent to prepare a solution with a mass fraction of 10%, and the solution was then loaded into an electrospinning device, and the voltage was set to 18 kV, the propulsion rate was 1.0 mL / h, and the receiving distance was 15 cm to prepare a 300 mm electrospun fiber layer; during this period, the relative position of the electrospinning nozzle and the meltblowing die was adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then, the meltblowing hot air pressure was reduced by 0.002 MPa / min, the meltblowing die temperature was increased by 0.2 ° C / min, the electrospinning propulsion rate was increased by 0.01 mL / min, and the voltage was reduced by 0.1 kV / min. The conditions were adjusted for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5 kV / m was applied to obtain a filter material;

[0129] A5, using wavelength 3um, power density 3W / cm 2The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145°C, and then dried in an oven at a temperature of 190°C for 45 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

[0130] Preparation Example 24

[0131] A heat-resistant high-molecular polypropylene filter material, which differs from Preparation Example 10 in that the preparation method is as follows:

[0132] A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix at a temperature of 60° C. and a speed of 800 r / min for 10 min to obtain a mixed raw material;

[0133] A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: 180°C in zone 1, 190°C in zone 2, 200°C in zone 3, 210°C in zone 4, and 220°C in the die. The screw speed was controlled at 180 r / min and the feed rate was 30 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch.

[0134] A3. Mix the modified polypropylene masterbatch obtained in A2 with dicumyl peroxide in a low-speed mixer at a temperature of 40° C. and a rotation speed of 30 r / min for 10 min to obtain a mixed masterbatch;

[0135] A4, the mixed masterbatch obtained in A3 was added to the meltblowing equipment, and the meltblowing die temperature, hot air temperature, hot air pressure and receiving distance were set to 230 ° C, 250 ° C, 0.2 MPa, and 15 cm, respectively, to prepare a meltblown fiber layer to 0.2 mm; the mixed masterbatch was then dissolved in a mixed solvent to prepare a solution with a mass fraction of 10%, and the solution was then loaded into an electrospinning device, and the voltage was set to 18 kV, the propulsion rate was 1.0 mL / h, and the receiving distance was 15 cm to prepare a 300 mm electrospun fiber layer; during this period, the relative position of the electrospinning nozzle and the meltblowing die was adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then, the meltblowing hot air pressure was reduced by 0.002 MPa / min, the meltblowing die temperature was increased by 0.2 ° C / min, the electrospinning propulsion rate was increased by 0.01 mL / min, and the voltage was reduced by 0.1 kV / min. The conditions were adjusted for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5 kV / m was applied to obtain a filter material;

[0136] A5, using wavelength 5um, power density 3W / cm 2The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145°C, and then dried in an oven at a temperature of 200°C for 60 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

[0137] Preparation Examples 25-32

[0138] A heat-resistant high-molecular polypropylene filter material is different from Preparation Example 10 in that the usage of the inorganic fillers used in its components is different. The specific corresponding relationships are shown in the following table.

[0139] Table: Comparison of the use of inorganic fillers in Preparation Examples 25-32

[0140] Group Inorganic fillers Preparation Example 25 Prepared from Preparation Example 2 Preparation Example 26 Prepared from Preparation Example 3 Preparation Example 27 Prepared from Preparation Example 4 Preparation Example 28 Prepared from Preparation Example 5 Preparation Example 29 Prepared from Preparation Example 6 Preparation Example 30 Prepared from Preparation Example 7 Preparation Example 31 Prepared from Preparation Example 8 Preparation Example 32 Prepared from Preparation Example 9

[0141] Performance testing

[0142] The heat-resistant high-molecular-weight polypropylene filter materials prepared in each embodiment were selected for testing. The test subjects were 230 parts of the heat-resistant high-molecular-weight polypropylene filter materials, 10 parts in each group; their heat resistance, mechanical strength and filtration performance were tested. The specific testing steps are as follows:

[0143] Heat resistance:

[0144] First, the heat-resistant high-molecular-weight polypropylene filter material prepared in the example was sampled and its heat deformation temperature was measured using a heat deformation Vicat temperature measuring instrument to characterize the heat resistance of the heat-resistant high-molecular-weight polypropylene filter material. The test results and evaluation criteria are as follows:

[0145] Heat deformation temperature>130℃ (considered to be heat resistant);

[0146] Heat deformation temperature <130°C (considered as weak heat resistance).

[0147] Mechanical strength:

[0148] First, the heat-resistant high-molecular-weight polypropylene filter material prepared in the example was sampled, and its breaking strength was measured using an electronic universal testing machine, and the elongation at break was calculated to characterize the mechanical strength of the heat-resistant high-molecular-weight polypropylene filter material. The test results and evaluation criteria are as follows:

[0149] Breaking strength>25MPa, breaking elongation>300% (considered as high mechanical strength);

[0150] The breaking strength is less than 25 MPa, and the breaking elongation is less than 300% (considered as low mechanical strength).

[0151] Filtration performance:

[0152] The heat-resistant high-molecular-weight polypropylene filter material prepared in the examples was sampled. An aerosol generator was used to measure the concentration of aerosol particles before and after the filter material filtered aerosol particles with a particle size of 0.3 μm. The filtration efficiency was calculated. An air permeability tester was used to measure the volume of air passing through the sample per unit time at 200 MPa to obtain the air permeability. This data was used to characterize the filtration performance of the heat-resistant high-molecular-weight polypropylene filter material. The test results and evaluation criteria are as follows:

[0153] Filtration efficiency>99%, air permeability>200L / (m 2 ·s) (considered as strong filtering performance);

[0154] Filtration efficiency <99%, air permeability <200L / (m 2 ·s) (considered as weak filtering performance).

[0155] It should be specifically noted that the heat-resistant high molecular weight polypropylene filter material prepared above is a heat-resistant high molecular weight polypropylene filter material produced in a normal production method. The data of the defective heat-resistant high molecular weight polypropylene filter material produced are discarded.

[0156] Examples 1-5

[0157] A heat-resistant high-molecular polypropylene filter material, and the corresponding relationship between its preparation methods are shown in the following table.

[0158] Table: Comparison of usage of heat-resistant high molecular weight polypropylene filter materials in Examples 1-5

[0159]

[0160]

[0161] The heat-resistant high-molecular-weight polypropylene filter materials in Examples 1-5 were sampled and tested for heat deformation temperature, breaking strength, breaking elongation, filtration efficiency, and air permeability according to the above measurement steps and measurement standards. The average values ​​of the test results were recorded in the table below.

[0162] Table: Performance test results of heat deformation temperature, breaking strength, breaking elongation, filtration efficiency and air permeability of Examples 1-5

[0163]

[0164] As can be seen from the above table, in the preparation process of the heat-resistant polymer polypropylene filter material in Examples 1-5, all of them have the effect of improving the production effect of the heat-resistant polymer polypropylene filter material. 4-vinyl benzoic acid glycidyl ester is copolymerized with propylene block as a functional monomer, and epoxy groups are introduced into the polypropylene molecular chain, which significantly improves the cross-linking ability of the material, thereby enhancing the heat resistance and mechanical properties of the material. The addition of boron nitride surface-modified with a silane coupling agent effectively improves its dispersibility in the polypropylene matrix. The high thermal conductivity and mechanical properties of boron nitride are utilized to further improve the heat resistance and strength of the material. The melt-blown fiber and the electrospun fiber are mixed, which not only provides sufficient mechanical strength and stability for the entire filter material, but also can efficiently intercept tiny particles, improve the filtration accuracy, and achieve a smooth transition between fibers of different sizes, which not only ensures filtration efficiency but also takes into account air permeability; thereby achieving the purpose of improving the production effect of the heat-resistant polymer polypropylene filter material;

[0165] Its heat deformation temperature is 137.2-137.8℃, which is considered to be heat-resistant; its breaking strength is 31.3-32.1MPa, and its elongation at break is 355.2-356.1%, which is considered to be high mechanical strength; its filtration efficiency is 99.84-99.87%, and its air permeability is 256.0-256.5L / (m 2 ·s), considered as strong filtering performance;

[0166] It can be seen that when the production raw materials are certain, the production effect of the heat-resistant polymer polypropylene filter material can be increased by adjusting the proportion of the raw materials. Combined with the data in the above table, it is not difficult to see that when preparing the heat-resistant polymer polypropylene filter material, the heat-resistant polymer polypropylene filter material prepared using 1.2 parts of inorganic filler, 75 parts of polypropylene resin, 8 parts of 4-methyl-1-pentene, 0.2 parts of antioxidant, 0.2 parts of calcium stearate, 0.4 parts of diisopropyl benzene peroxide, and 3 parts of 4-vinyl benzoic acid glycidyl ester has the best heat resistance, mechanical strength and filtration performance, as obtained in Examples 1-5.

[0167] Examples 6-15

[0168] A heat-resistant high-molecular polypropylene filter material, and the corresponding relationship between its preparation methods are shown in the following table.

[0169] Table: Comparison of usage of heat-resistant high molecular weight polypropylene filter materials in Examples 6-15

[0170]

[0171]

[0172] The heat-resistant high-molecular-weight polypropylene filter materials in Examples 6-15 were sampled and tested for heat deformation temperature, breaking strength, breaking elongation, filtration efficiency, and air permeability according to the above measurement steps and measurement standards. The average values ​​of the test results were recorded in the table below.

[0173] Table: Performance test results of heat deformation temperature, breaking strength, elongation at break, filtration efficiency and air permeability of Examples 1, 6-15

[0174]

[0175] As can be seen from the above table, in the preparation process of the heat-resistant polymer polypropylene filter material in Examples 1, 6-11, the production effect of the heat-resistant polymer polypropylene filter material is well improved. 4-vinyl benzoic acid glycidyl ester is copolymerized with propylene block as a functional monomer, and epoxy groups are introduced into the polypropylene molecular chain, which significantly improves the cross-linking ability of the material, thereby enhancing the heat resistance and mechanical properties of the material. The addition of boron nitride surface-modified with a silane coupling agent effectively improves its dispersibility in the polypropylene matrix. The high thermal conductivity and mechanical properties of boron nitride are utilized to further improve the heat resistance and strength of the material. The melt-blown fiber and the electrospun fiber are mixed, which not only provides sufficient mechanical strength and stability for the entire filter material, but also can efficiently intercept tiny particles, improve the filtration accuracy, and achieve a smooth transition between fibers of different sizes, thereby ensuring filtration efficiency and taking into account air permeability; thereby achieving the purpose of improving the production effect of the heat-resistant polymer polypropylene filter material;

[0176] Its heat deformation temperature is 137.2-137.8℃, which is considered to be heat-resistant; its breaking strength is 31.3-31.9MPa, and its elongation at break is 355.2-355.9%, which is considered to be high mechanical strength; its filtration efficiency is 99.84-99.88%, and its air permeability is 256.1-256.7L / (m 2 ·s), considered as strong filtering performance;

[0177] It can be seen that when the production raw materials are certain, the production effect of heat-resistant polymer polypropylene filter materials can be increased by adjusting the preparation conditions. Combined with the data in the above table, it is not difficult to see that when preparing heat-resistant polymer polypropylene filter materials, the mixing process temperature and rotation speed are increased during the preparation process, the melt blending process temperature and rotation speed are increased, the feeding speed is reduced, the melt blowing process temperature and pressure, the electrospinning process voltage is increased, the propulsion rate is reduced, the infrared radiation wavelength, drying temperature and time are increased, the heat resistance, mechanical strength and filtration performance of the heat-resistant polymer polypropylene filter material prepared thereby are improved. The reason for this is that the increase in mixing temperature increases the activity of molecular chains, promotes the interface wetting of nanofillers and resins, reduces filler agglomeration, and enhances interfacial stress transfer, thereby improving mechanical strength and heat resistance; the increase in mixing speed strengthens the shear force, accelerates the uniform dispersion of components, especially the distribution of cross-linking agents, and the increase in melt blending process temperature reduces Low melt viscosity promotes the grafting reaction of comonomers and polypropylene, introduces more epoxy groups, enhances the crosslinking density, and at the same time improves the dispersibility of nanofillers. The screw speed is increased, the shear rate is increased, the dispersed phase size is refined, and a more uniform microstructure is formed. The feeding rate is reduced, the residence time of the material in the extruder is extended, chemical reactions and melt homogenization are promoted, unreacted monomer residues are reduced, and the thermal stability of the material is improved. The melt-blowing temperature and pressure increase will reduce the melt viscosity, promote fiber refinement, increase the porosity of the support layer, and optimize the balance between air permeability and filtration efficiency; increasing the electrospinning voltage will enhance the electric field strength, refine the fiber diameter, and improve the interception efficiency. The reduction in the propulsion rate will increase the stretching time of the solution in the electric field and reduce the fiber bead defects. The optimization of the infrared radiation wavelength promotes the diffusion of molecular chains between adjacent layers and improves the interfacial bonding strength. The increase in the drying temperature and the extension of the drying time will lead to an increase in the degree of crosslinking, as obtained from Examples 1 and 8-15.

[0178] Examples 16-19

[0179] A heat-resistant high-molecular polypropylene filter material, and the corresponding relationship between its preparation methods are shown in the following table.

[0180] Table: Comparison of usage of heat-resistant high molecular weight polypropylene filter materials in Examples 16-19

[0181] Group Heat-resistant polymer polypropylene filter material Example 16 Prepared from Preparation Example 25 Example 17 Prepared from Preparation Example 26 Example 18 Prepared from Preparation Example 27 Example 19 Prepared from Preparation Example 28

[0182] The heat-resistant high-molecular-weight polypropylene filter materials in Examples 16-19 were sampled and their heat deformation temperature, breaking strength, breaking elongation, filtration efficiency, and air permeability were tested according to the above measurement steps and measurement standards. The average values ​​of the test results were recorded in the table below.

[0183] Table: Performance test results of heat deformation temperature, breaking strength, elongation at break, filtration efficiency and air permeability of Examples 1, 16-19

[0184]

[0185]

[0186] As can be seen from the above table, in the preparation process of the heat-resistant polymer polypropylene filter material in Examples 1 and 16-19, the production effect of the heat-resistant polymer polypropylene filter material is well improved. 4-vinyl benzoic acid glycidyl ester is copolymerized with propylene block as a functional monomer, and epoxy groups are introduced into the polypropylene molecular chain, which significantly improves the cross-linking ability of the material, thereby enhancing the heat resistance and mechanical properties of the material. The addition of boron nitride surface-modified with a silane coupling agent effectively improves its dispersibility in the polypropylene matrix. The high thermal conductivity and mechanical properties of boron nitride are utilized to further improve the heat resistance and strength of the material. The melt-blown fiber and the electrospun fiber are mixed, which not only provides sufficient mechanical strength and stability for the entire filter material, but also can efficiently intercept tiny particles, improve the filtration accuracy, and achieve a smooth transition between fibers of different sizes, thereby ensuring filtration efficiency and taking into account air permeability; thereby achieving the purpose of improving the production effect of the heat-resistant polymer polypropylene filter material;

[0187] Its heat deformation temperature is 137.2-138.4℃, which is considered to be heat-resistant; its breaking strength is 31.3-32.3MPa, and its elongation at break is 355.2-356.6%, which is considered to be high mechanical strength; its filtration efficiency is 99.84-99.91%, and its air permeability is 256.1-257.4L / (m 2 ·s), considered as strong filtering performance;

[0188] It can be seen that when the production raw materials are certain, the production effect of the heat-resistant polymer polypropylene filter material can be increased by adjusting the preparation conditions. Combined with the data in the above table, it is not difficult to see that when preparing the inorganic filler, the inorganic filler prepared by using 3 parts of silane coupling agent KH-570 and 100 parts of boron nitride powder has the best effect, and the corresponding heat-resistant polymer polypropylene filter material has the highest heat resistance, mechanical strength and filtration performance. The reason for this is that the silane coupling agent KH-570 has a special molecular structure, and the alkoxy group at one end can be hydrolyzed to form a silanol group, which undergoes a condensation reaction with the hydroxyl group on the surface of the boron nitride powder to form a stable chemical bond. The polarity of the boron nitride powder surface changes, the surface energy is reduced, and a steric hindrance effect is generated, which prevents the agglomeration of the boron nitride particles and makes the boron nitride dispersed in the polypropylene matrix in a relatively uniform state; obtained by Examples 1 and 16-19.

[0189] Examples 20-23

[0190] A heat-resistant high-molecular polypropylene filter material, and the corresponding relationship between its preparation methods are shown in the following table.

[0191] Table: Comparison of usage of heat-resistant high molecular weight polypropylene filter materials in Examples 20-23

[0192] Group Heat-resistant polymer polypropylene filter material Example 20 Prepared from Preparation Example 29 Example 21 Prepared from Preparation Example 30 Example 22 Prepared from Preparation Example 31 Example 23 Prepared from Preparation Example 32

[0193] The heat-resistant high-molecular-weight polypropylene filter materials in Examples 20-23 above were sampled and their heat deformation temperature, breaking strength, breaking elongation, filtration efficiency and air permeability were tested according to the above-mentioned measurement steps and measurement standards. The average values ​​of the test results were recorded in the following table.

[0194] Table: Performance test results of heat deformation temperature, breaking strength, elongation at break, filtration efficiency and air permeability of Examples 1, 20-23

[0195]

[0196]

[0197] As can be seen from the above table, in the preparation process of the heat-resistant polymer polypropylene filter material in Examples 1, 20-23, the production effect of the heat-resistant polymer polypropylene filter material is well improved. 4-vinyl benzoic acid glycidyl ester is copolymerized with propylene block as a functional monomer, and epoxy groups are introduced into the polypropylene molecular chain, which significantly improves the cross-linking ability of the material, thereby enhancing the heat resistance and mechanical properties of the material. The addition of boron nitride surface-modified with a silane coupling agent effectively improves its dispersibility in the polypropylene matrix. The high thermal conductivity and mechanical properties of boron nitride are utilized to further improve the heat resistance and strength of the material. The melt-blown fiber and the electrospun fiber are mixed, which not only provides sufficient mechanical strength and stability for the entire filter material, but also can efficiently intercept tiny particles, improve the filtration accuracy, and achieve a smooth transition between fibers of different sizes, thereby ensuring filtration efficiency and taking into account air permeability; thereby achieving the purpose of improving the production effect of the heat-resistant polymer polypropylene filter material;

[0198] Its heat deformation temperature is 137.2-138.4℃, which is considered to be heat-resistant; its breaking strength is 31.3-32.3MPa, and its elongation at break is 355.2-356.6%, which is considered to be high mechanical strength; its filtration efficiency is 99.84-99.91%, and its air permeability is 256.1-257.4L / (m 2 ·s), considered as strong filtering performance;

[0199] It can be seen that when the production raw materials are certain, the production effect of heat-resistant polymer polypropylene filter materials can be increased by adjusting the preparation conditions. Combined with the data in the above table, it is not difficult to see that when preparing inorganic fillers, increasing the speed and stirring time of the silane coupling agent solution preparation process, increasing the drying temperature and time of the boron nitride powder, and the speed, temperature and time of the mixing process, the heat resistance, mechanical strength and filtration performance of the corresponding heat-resistant polymer polypropylene filter materials are all improved. The reason for this is that higher speed and longer stirring time can fully disperse the silane coupling agent in the solvent, and the silane coupling agent molecules are more evenly distributed in the solvent system under rapid stirring, avoiding the situation where the local concentration is too high or too low. Properly increasing the speed and stirring time is conducive to the hydrolysis reaction, so that more silane coupling agents are converted into active The invention discloses a novel silanol form, thereby enhancing the binding ability with boron nitride, increasing the drying temperature and extending the drying time can more effectively remove moisture from the surface of boron nitride, so that the silane coupling agent can better chemically bond with the active sites on the surface of boron nitride in subsequent treatment, thereby enhancing the interfacial bonding force, and appropriate high-temperature drying can make the crystal structure of boron nitride more stable, and a higher rotation speed and a longer mixing time can fully mix the modified boron nitride powder with the silane coupling agent solution, further ensuring that the silane coupling agent is evenly coated on the surface of boron nitride, increasing the mixing temperature can accelerate the chemical reaction rate, promote the chemical bonding between the silane coupling agent and boron nitride and between the modified boron nitride and the polypropylene matrix, improve the molecular chain movement, optimize the pore structure of the filter material, and improve the filtration performance, as obtained by Examples 1 and 20-21.

[0200] It can be seen that when the production raw materials are constant, the production effect of the heat-resistant polymer polypropylene filter material can be increased by adjusting the preparation conditions. Combined with the data in the above table, it is not difficult to see that when preparing inorganic fillers, reducing the volume ratio of the silane coupling agent solution, the heat resistance, mechanical strength and filtration performance of the corresponding heat-resistant polymer polypropylene filter material do not change much, as obtained from Examples 1 and 22-23.

[0201] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A method for preparing a heat-resistant high-molecular polypropylene filter material, characterized in that: The following steps are involved: A1. Add inorganic filler, 4-vinyl benzoic acid glycidyl ester, polypropylene resin, 4-methyl-1-pentene, antioxidant and calcium stearate into a high-speed mixer, and mix for 10-20 minutes at a temperature of 60-80° C. and a rotation speed of 800-1200 r / min to obtain a mixed raw material; A2. The mixed raw materials obtained in A1 were melt-blended through a twin-screw extruder. The temperature of each section of the twin-screw extruder was set as follows: 180-190° C. in zone 1, 190-200° C. in zone 2, 200-210° C. in zone 3, 210-220° C. in zone 4, and 220-230° C. in the die. The screw speed was controlled at 180-220 r / min and the feed rate was 20-30 kg / h. After melt-blending, the mixed raw materials were extruded and water-cooled to obtain modified polypropylene masterbatch. A3, the modified polypropylene masterbatch obtained in A2 and dicumyl peroxide were mixed in a low-speed mixer at a temperature of 40-50° C. and a rotation speed of 30-50 r / min for 10-15 min to obtain a mixed masterbatch; A4, the mixed masterbatch obtained in A3 was added to the melt-blowing equipment, the melt-blowing die temperature was set to 230-240 ° C, the hot air temperature was set to 250-260 ° C, the hot air pressure was set to 0.2-0.3 MPa, the receiving distance was set to 15 cm, and the melt-blown fiber layer was prepared to 0.2 mm; then the mixed masterbatch was dissolved in the mixed solvent to prepare a solution with a mass fraction of 10%, and then the solution was loaded into the electrospinning device, the voltage was set to 18-22 kV, the propulsion rate was set to 0.5-1.0 mL / h, the receiving distance was set to 15 cm, and the melt-blown fiber layer was prepared. 300mm electrospun fiber layer; during the process, the relative positions of the electrospinning nozzle and the meltblowing die head were adjusted so that the electrospun fiber fell on the intersection area of ​​the meltblown fiber layer; then, the meltblowing hot air pressure was reduced at a rate of 0.002MPa / min, the meltblowing die head temperature was increased at a rate of 0.2℃ / min, the electrospinning propulsion rate was increased at a rate of 0.01mL / min, and the voltage was reduced at a rate of 0.1kV / min for 15 minutes, and then maintained for 5 minutes, during which a directional electric field of 5kV / m was applied to obtain a filter material; A5, using wavelength 2-5um, power density 3W / cm 2 The filter material obtained by A4 was subjected to infrared radiation and hot pressing for 90 seconds at a pressure of 0.5 MPa and a temperature of 145° C., and then dried in an oven at a temperature of 180-200° C. for 30-60 minutes to obtain a heat-resistant high molecular weight polypropylene filter material.

2. The method for preparing a heat-resistant high molecular weight polypropylene filter material according to claim 1, characterized in that: The raw material components and weight proportions of the heat-resistant high molecular weight polypropylene filter material are as follows: 0.8-1.5 parts of inorganic filler, 65-85 parts of polypropylene resin, 6-10 parts of 4-methyl-1-pentene, 0.1-0.3 parts of antioxidant, 0.1-0.3 parts of calcium stearate, 0.2-0.6 parts of dicumyl peroxide, and 1-5 parts of 4-vinyl benzoic acid glycidyl ester.

3. The method for preparing a heat-resistant high molecular weight polypropylene filter material according to claim 1, characterized in that: The inorganic filler is prepared from silane coupling agent KH-570 and boron nitride powder.

4. The method for preparing a heat-resistant high molecular weight polypropylene filter material according to claim 1, characterized in that: The inorganic filler comprises the following preparation steps: C1. Place silane coupling agent KH-570 in 10-20 times the volume of anhydrous ethanol, and then use a stirrer at a speed of 200-300 rpm to stir for 10-15 minutes to obtain a silane coupling agent solution; C2. Place the boron nitride powder in an oven, dry it at 100-120° C. for 2-3 hours, cool it to room temperature, and then transfer it to a high-speed mixer. Then, start the high-speed mixer and adjust the speed to 500-800 r / min. Use a dropper to add the silane coupling agent solution obtained in C1 dropwise to the mixer at a dropping speed of 2 drops / s. After the addition is complete, continue stirring at 80-100° C. for 30-60 minutes to obtain a mixed product. C3. Transfer the mixed product obtained in C2 to a vacuum drying oven, dry it at a temperature of 60-80°C for 6-8 hours, then place it in a ball mill, and ball mill it at a speed of 300 r / min for 3 hours. Then, select a 300-mesh sieve for sieving to obtain an inorganic filler.

5. A heat-resistant high molecular weight polypropylene filter material formulation according to claim 1, characterized in that: The components and weight proportions of the raw materials for preparing the inorganic filler are as follows: Silane coupling agent KH-570 (0.5-5) parts, boron nitride powder 100 parts.

6. The method for preparing a heat-resistant high molecular weight polypropylene filter material according to claim 1, characterized in that: The mixed solvent consists of xylene and tetrahydrofuran in a volume ratio of 3:

1.

7. The method for preparing a heat-resistant high molecular weight polypropylene filter material according to claim 1, characterized in that: The antioxidant is antioxidant 1010.

8. A heat-resistant high-molecular polypropylene filter material prepared according to the preparation method according to any one of claims 1 to 7.

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