High filtration polyethylene nonwoven material and method of making same

Abstract

The application provides a high-filtration polyethylene nonwoven material and a preparation method thereof. The high-filtration polyethylene nonwoven material comprises a spun-bond layer and a melt-blown layer, the melt-blown layer is formed by melt-blown spinning of a first high-melt-index polyethylene and a second high-melt-index polyethylene, the melt indexes of the first high-melt-index polyethylene and the second high-melt-index polyethylene are greater than or equal to 200 g / 10 min, and the melt indexes of the first high-melt-index polyethylene and the second high-melt-index polyethylene are different. The melt-blown layer is prepared by melt-blown spinning of high-melt-index polyethylene, and two high-melt-index polyethylenes with different melt indexes are used, so that the crystallization rates of the polyethylenes with different melt indexes are utilized to induce the orientation of molecular chains in the amorphous region during the crystallization process, thereby improving the fiber reinforcement effect and effectively solving the problem of low mechanical strength of the melt-blown fiber.

Description

Technical Field

[0001] This invention relates to the field of nonwoven materials, specifically to a high-filtration polyethylene nonwoven material and its preparation method. Background Technology

[0002] Domestically produced medical protective materials mostly use meltblown polypropylene microfiber nonwoven materials as the core filter layer. However, polypropylene meltblown fabric requires sterilization with ethylene oxide, resulting in sterilization time and ethylene oxide desorption time of over 8 days for protective products. Furthermore, protective clothing made from polypropylene nonwoven fabric has a short shelf life and is not suitable for long-term storage. Therefore, developing radiation-resistant polyethylene microfiber nonwoven materials is of great significance.

[0003] Polyethylene meltblown material is an important material for breathable membranes in medical protective clothing and surgical gowns. Through a special process, tiny and uniform micropores and channels of 1-2 μm can be formed on the surface of polyethylene, achieving the goal of allowing moisture to pass through while simultaneously blocking blood and other liquids. This fulfills the "three-fold resistance and one-fold protection" requirements of protective clothing, providing better protection and comfort for medical personnel.

[0004] Polyethylene resin possesses excellent chemical stability and radiation resistance, leading DuPont to select it as the polymer matrix material for manufacturing limited-edition high-end protective clothing. However, polyethylene has a low melt index, high melt viscosity, and is insoluble in solvents at room temperature and pressure, making it unsuitable for processing into microfiber nonwoven materials using conventional spinning methods. Compared to traditional nonwoven fabric technology, flash evaporation technology for polyethylene nonwovens, invented by DuPont, has been used for the industrial development of high-density polyethylene nonwovens. Its product, Tyvek, is used in advanced medical protective products and has been selected as a protective textile specifically for Ebola virus protection in Africa. Flash evaporation technology involves spraying a saturated solution of high-density polyethylene under high temperature and pressure into the atmosphere to obtain nonwoven fabric. However, flash evaporation presents environmental pollution problems, hindering industrialization. Summary of the Invention

[0005] The main objective of this invention is to provide a high-filtration polyethylene nonwoven material and its preparation method, so as to overcome the problems of meltblown polypropylene fibers being unable to withstand rapid sterilization by radiation, and meltblown polyethylene microfibers having low filtration efficiency and insufficient mechanical strength in the prior art.

[0006] To achieve the above objectives, the present invention provides a high-filtration polyethylene nonwoven material, comprising a spunbond layer and a meltblown layer, wherein the meltblown layer is formed by meltblowing a first high melt index polyethylene and a second high melt index polyethylene, wherein the melt index of the first high melt index polyethylene and the second high melt index polyethylene are both greater than or equal to 200 g / 10 min, and the melt indexes of the first high melt index polyethylene and the second high melt index polyethylene are different.

[0007] The high-filtration polyethylene nonwoven material of the present invention comprises a first high melt index polyethylene with a melt index of 200-600 g / 10 min and a second high melt index polyethylene with a melt index of 1000-1500 g / 10 min; the mass ratio of the first high melt index polyethylene to the second high melt index polyethylene is 5-20:80-95.

[0008] The high-filtration polyethylene nonwoven material of the present invention, wherein the spunbond layer is a polyethylene spunbond layer.

[0009] The high-filtration polyethylene nonwoven material of the present invention further includes a spinning aid in the meltblown layer, wherein the spinning aid is at least one of dicumyl peroxide and 4,4'-thiobis(6-tert-butyl-3-methylphenol); the mass of the dicumyl peroxide is 0.01 to 0.2% of the sum of the masses of the first high melt index polyethylene and the second high melt index polyethylene, and the mass of the 4,4'-thiobis(6-tert-butyl-3-methylphenol) is 0.1 to 0.2% of the sum of the masses of the first high melt index polyethylene and the second high melt index polyethylene.

[0010] The high-filtration polyethylene nonwoven material of the present invention has a transverse and longitudinal tensile strength ≥55N, a filtration efficiency of 95% to 97%, and a resistance <220Pa.

[0011] To achieve the above objectives, the present invention also provides a method for preparing a high-filtration polyethylene nonwoven material, wherein the high-filtration polyethylene nonwoven material comprises a spunbond layer and a meltblown layer, and the preparation method includes:

[0012] Step 1: Mix and granulate the first high melt index polyethylene and the second high melt index polyethylene;

[0013] Step 2: The resin obtained in Step 1 is melt-blown spun to obtain a melt-blown layer;

[0014] Step 3: Composite the spunbond layer with the meltblown layer to obtain a high-filtration polyethylene nonwoven material;

[0015] The melt index of both the first high melt index polyethylene and the second high melt index polyethylene is greater than or equal to 200 g / 10 min, and the melt indexes of the first high melt index polyethylene and the second high melt index polyethylene are different.

[0016] The method for preparing high-filtration polyethylene nonwoven material according to the present invention, wherein the melt index of the first high melt index polyethylene is 200-600 g / 10 min, and the melt index of the second high melt index polyethylene is 1000-1500 g / 10 min.

[0017] The method for preparing high-filtration polyethylene nonwoven material according to the present invention, wherein the mass ratio of the first high melt index polyethylene to the second high melt index polyethylene is 5-20:80-95.

[0018] The method for preparing high-filtration polyethylene nonwoven material according to the present invention includes, in step 1, a spinning aid is added during the mixing and granulation process of the first high melt index polyethylene and the second high melt index polyethylene. The spinning aid is at least one of dicumyl peroxide and 4,4'-thiobis(6-tert-butyl-3-methylphenol). The mass of dicumyl peroxide is 0.01 to 0.2% of the sum of the masses of the first high melt index polyethylene and the second high melt index polyethylene, and the mass of 4,4'-thiobis(6-tert-butyl-3-methylphenol) is 0.1 to 0.2% of the sum of the masses of the first high melt index polyethylene and the second high melt index polyethylene.

[0019] The method for preparing high-filtration polyethylene nonwoven material according to the present invention includes step 2, which is carried out in a meltblown spinning machine with a screw temperature of 210-240°C, a hot air temperature of 230-260°C, a hot air frequency of 40-50Hz, and a receiving distance of 20-35cm.

[0020] The beneficial effects of this invention are:

[0021] (1) The present invention uses high melt index polyethylene to prepare meltblown layer by meltblown spinning, and uses two high melt index polyethylenes with different melt indices. The different melt index polyethylenes can be used to take advantage of the different crystallization rates and fluidity to induce molecular chain orientation in the amorphous region during the crystallization process, thereby improving the fiber reinforcement and effectively solving the problem of low mechanical strength of meltblown fiber.

[0022] (2) In addition, the present invention utilizes polyethylene with different melt indexes to construct a molecular chain structure with a comb-like structure to further regulate the crystallization and orientation of the fiber, thereby further enhancing the strength of meltblown polyethylene microfiber.

[0023] (3) The polyethylene with different melt indexes has different fluidity. During the meltblown process, an inlaid composite nonwoven structure is formed with coarser fibers as the fabric skeleton and finer fibers as the functional filter layer, so that the meltblown fiber has a high filtration efficiency. Attached Figure Description

[0024] Figure 1 This is the carbon NMR spectrum of the high melt flow index polyethylene resin of this invention;

[0025] Figure 2 Scanning electron microscope image of meltblown microfibers obtained from meltblown single melt index polyethylene;

[0026] Figure 3 This is a scanning electron microscope image of the meltblown polyethylene microfiber nonwoven material of Embodiment 1 of the present invention;

[0027] Figure 4 This is a statistical table of the diameter of the polyethylene microfiber nonwoven material under a scanning electron microscope, as shown in Example 1 of the present invention.

[0028] Figure 5 A photograph of the meltblown polyethylene microfiber nonwoven material of Embodiment 1 of the present invention;

[0029] Figure 6 This is a schematic diagram of the meltblown layer processing process of the present invention.

[0030] In the attached figures, the following labels are used:

[0031] 1 Feeding device

[0032] 2. Screw extruder

[0033] 3 Metering pump

[0034] 4. Web forming device

[0035] 5. Meltblown die head

[0036] 7. Winding device Detailed Implementation

[0037] The technical solution of the present invention will be described in detail below. The following embodiments are implemented under the premise of the technical solution of the present invention and a detailed implementation process is given. However, the protection scope of the present invention is not limited to the following embodiments. Structures or experimental methods that do not specify specific conditions in the following embodiments are generally performed under conventional conditions.

[0038] This invention provides a high-filtration polyethylene nonwoven material, comprising a spunbond layer and a meltblown layer. The meltblown layer is formed by meltblowing a first high melt index polyethylene and a second high melt index polyethylene. The melt index of both the first and second high melt index polyethylene is greater than or equal to 200 g / 10 min (wherein, melt index refers to the melt index tested at a load of 2.16 kg and a temperature of 190 °C), and the melt indices of the first and second high melt index polyethylene are different.

[0039] This invention uses high melt index polyethylene to prepare a meltblown layer through meltblown spinning. By using two high melt index polyethylenes with different melt indices, the different crystallization rates and fluidity of the polyethylenes can be utilized to induce molecular chain orientation in the amorphous region during the crystallization process, thereby improving the fiber reinforcement and effectively solving the problem of low mechanical strength of meltblown fibers.

[0040] In addition, the polyethylenes of different high melt indexes of the present invention have different fluidity, and during the meltblown process, an inlaid composite nonwoven structure is formed with coarser fibers generated from low melt index polyethylene as the fabric skeleton and finer fibers generated from high melt index polyethylene as the functional filter layer, thereby giving the meltblown fiber a high filtration efficiency.

[0041] In one embodiment, the melt index of the first high melt index polyethylene is 200–600 g / 10 min, and the melt index of the second high melt index polyethylene is 1000–1500 g / 10 min (2.16 kg, 190 °C). In another embodiment, the mass ratio of the first high melt index polyethylene to the second high melt index polyethylene is 5–20:80–95.

[0042] In one embodiment, a spinning aid, such as a processing aid or antioxidant, is also added to the meltblown layer of the present invention. Specifically, the spinning aid is, for example, at least one of dicumyl peroxide and 4,4'-thiobis(6-tert-butyl-3-methylphenol); the mass of dicumyl peroxide is 0.01 to 0.2% of the sum of the masses of the first high melt index polyethylene and the second high melt index polyethylene, and the mass of 4,4'-thiobis(6-tert-butyl-3-methylphenol) is 0.1 to 0.2% of the sum of the masses of the first high melt index polyethylene and the second high melt index polyethylene.

[0043] This invention combines two resins with different high melt flow indices and then uses a small amount of dicumyl peroxide as an additive for trace crosslinking to prepare a self-reinforced polyethylene microfiber nonwoven material with high filtration efficiency. This solves the problems of existing meltblown polypropylene fibers being unable to withstand rapid sterilization by radiation, meltblown polyethylene microfiber having low filtration efficiency and insufficient mechanical strength.

[0044] In one embodiment, the spinning aid of the present invention is added during the mixing and granulation process of the first high melt index polyethylene and the second high melt index polyethylene. The spinning aid, such as dicumyl peroxide, preferentially reacts with the polyethylene with the higher melt index, inducing free radicals to form a polyethylene comb-chain structure with a relatively low melt index polyethylene as the backbone and a relatively high melt index polyethylene as the comb-like chain. The presence of this structure can efficiently induce nucleation during the polyethylene melt-blowing process, thereby inducing chain orientation under hot air micro-dragging to obtain self-reinforced polyethylene microfibers.

[0045] The spunbond layer of this invention is prepared by spunbonding. This invention does not specifically limit the preparation process of the spunbond layer; conventional preparation methods in the art are acceptable. In one embodiment, the spunbond layer of this invention is a polyethylene spunbond layer.

[0046] The high-filtration polyethylene nonwoven material of this invention has a tensile strength of ≥55N in both the transverse and longitudinal directions, a filtration efficiency of 95%–97%, and a resistance of <220Pa. Medical protective clothing and surgical gowns can be manufactured from this polyethylene nonwoven material.

[0047] This invention also provides a method for preparing the above-mentioned high-filtration polyethylene nonwoven material, wherein the high-filtration polyethylene nonwoven material includes a spunbond layer and a meltblown layer, and the preparation method includes:

[0048] Step 1: Mix and granulate the first high melt index polyethylene and the second high melt index polyethylene;

[0049] Step 2: The resin obtained in Step 1 is melt-blown spun to obtain a melt-blown layer;

[0050] Step 3: Composite the spunbond layer with the meltblown layer to obtain a high-filtration polyethylene nonwoven material;

[0051] Wherein, the melt index of both the first high melt index polyethylene and the second high melt index polyethylene is greater than or equal to 200 g / 10 min, and the melt indexes of the first high melt index polyethylene and the second high melt index polyethylene are different.

[0052] In one embodiment, the melt index of the first high melt index polyethylene is 200-600 g / 10 min, and the melt index of the second high melt index polyethylene is 1000-1500 g / 10 min; the mass ratio of the first high melt index polyethylene to the second high melt index polyethylene is 5-20:80-95.

[0053] The present invention does not particularly limit the mixing and granulation process of the first high melt index polyethylene and the second high melt index polyethylene. In one embodiment, the mixing and granulation of the first high melt index polyethylene and the second high melt index polyethylene are carried out in a twin-screw extruder. The temperature of the screw feed section to the homogenization section is set at 120-160°C, and the screw speed is, for example, 50-100 rpm.

[0054] In one embodiment, a spinning aid, such as a processing aid or antioxidant, is added during the mixing and granulation process of the first and second high melt index polyethylenes in step 1. Specifically, the spinning aid is at least one of dicumyl peroxide and 4,4'-thiobis(6-tert-butyl-3-methylphenol); the mass of dicumyl peroxide is 0.01 to 0.2% of the sum of the masses of the first and second high melt index polyethylenes, and the mass of 4,4'-thiobis(6-tert-butyl-3-methylphenol) is 0.1 to 0.2% of the sum of the masses of the first and second high melt index polyethylenes.

[0055] The spunbond layer of this invention is prepared by spunbonding. This invention does not specifically limit the preparation process of the spunbond layer; conventional preparation methods in the art are acceptable. In one embodiment, the spunbond layer of this invention is a polyethylene spunbond layer.

[0056] In one embodiment, after the first high melt index polyethylene and the second high melt index polyethylene are mixed and granulated, they enter a meltblown spinning machine. The screw temperature is 210-240°C, the hot air temperature is 230-260°C, the hot air frequency is 40-50Hz, and the receiving distance is 20-35cm. The polyethylene microfibers obtained by meltblowing fall onto the web forming device to form a meltblown layer.

[0057] The meltblown layer processing process of this invention is, for example, as follows: Figure 6 As shown, but the present invention is not limited thereto. The first high melt index polyethylene and the second high melt index polyethylene enter the screw extruder 2 through the feeding device 1. After the composite resin is extruded and granulated, it passes through the metering pump 3 and the meltblown die 5, and falls onto the web forming device 4. The resulting meltblown layer is wound up by the winding device 7.

[0058] Then, the spunbond layer and the meltblown layer are laminated to obtain a polyethylene nonwoven material. This invention does not particularly limit the process of laminating the spunbond layer and the meltblown layer; conventional processes in the art are acceptable, such as hot rolling.

[0059] The high-filtration polyethylene nonwoven material of this invention not only has high mechanical properties and high filtration performance, but also good barrier properties and radiation resistance. When electron beam radiation sterilization or X-ray sterilization is selected, the metering is controlled at 16-27 kgy, and there are no Escherichia coli colonies, bacterial colonies, fungal colonies, etc. after irradiation.

[0060] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0061] Source of raw materials or equipment:

[0062] (1) Raw materials:

[0063] High melt flow index polyethylene was supplied by the Daqing Chemical Research Center of China National Petroleum Corporation. Figure 1 This is the carbon NMR spectrum of the high melt flow index polyethylene resin of this invention;

[0064] Dicumyl peroxide, manufactured by Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0065] The antioxidant 4,4'-thiobis(6-tert-butyl-3-methylphenol) is produced by Wuhan Smike Biotechnology Co., Ltd.

[0066] (2) Equipment:

[0067] The twin-screw mixing equipment was designed and manufactured by Donghua University.

[0068] The meltblown spinning machine is manufactured by Tuoren Group.

[0069] Example 1

[0070] 1) Twin-screw extruder for preparing composite resins:

[0071] 20 kg of polyethylene powder with a melt index of 200 g / 10 min, 80 kg of polyethylene powder with a melt index of 1000 g / 10 min, 0.1 kg of dicumyl peroxide, and 0.1 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol) were thoroughly mechanically premixed and then added to a twin-screw extruder for reactive extrusion to obtain a composite resin. The temperature of the screw feed section to the homogenization section was set at 110–140 °C, and the screw speed was 50 rpm.

[0072] 2) Meltblown polyethylene microfiber nonwoven material:

[0073] Polyethylene microfibers were prepared by meltblowing the above-mentioned composite resin using a meltblown spinning machine from Tuoren Group. The screw compression and homogenization sections were set to temperatures of 120–240°C, the meltblown assembly temperature was 240°C, the hot air temperature was 260°C, the hot air frequency was 45Hz, and the receiving distance was 35cm. Meltblown polyethylene microfiber nonwoven material was obtained. Scanning electron microscope images are shown below. Figure 3 As shown in the table, the diameter statistics of scanning electron microscopes are as follows: Figure 4 As shown in the image, a photograph of the actual meltblown polyethylene microfiber nonwoven material is as follows: Figure 5 As shown. Figure 3 and 4 As shown, the diameter of the meltblown microfiber nonwoven material is mainly 1-2 μm, while also containing a small amount of coarse fibers of 5-9 μm. The transverse and longitudinal tensile strengths of the microfiber nonwoven material reach 5±0.13 N and 4.5±0.17 N, respectively.

[0074] Figure 2The image shows a scanning electron microscope (SEM) image of meltblown microfibers obtained from meltblown single melt index polyethylene (SMIPE). The fibers formed by SMIPE have a relatively uniform diameter. The microfibers prepared in this invention can form a nonwoven material with a coarse-fine interlocking spatial network structure.

[0075] 3) Polyethylene nonwoven materials:

[0076] The above-mentioned meltblown microfibers were combined with spunbond polyethylene nonwoven fabric to obtain polyethylene nonwoven material. When used to prepare face masks, the spunbond / meltblown layer basis weight ratio was controlled at 30–50:5–10, achieving a filtration efficiency of 96% and a resistance of <220 Pa. Protective clothing was also prepared based on spunbond polyethylene nonwoven fabric and the above-mentioned meltblown microfibers, with the spunbond / meltblown layer basis weight ratio controlled at 30–50:3–5. The transverse and longitudinal tensile strength of the protective clothing was greater than 65 N.

[0077] Example 2

[0078] 1) Twin-screw extruder for preparing composite resins:

[0079] Five kilograms of polyethylene powder with a melt index of 400 g / 10 min, 95 kilograms of polyethylene powder with a melt index of 1200 g / 10 min, 0.01 kilograms of dicumyl peroxide, and 0.2 kilograms of 4,4'-thiobis(6-tert-butyl-3-methylphenol) were thoroughly mechanically premixed and then added to a twin-screw extruder for reactive extrusion to obtain a composite resin. The temperature of the screw feed section to the homogenization section was set at 110–140°C, and the screw speed was 100 rpm.

[0080] 2) Meltblown polyethylene microfiber nonwoven material:

[0081] Polyethylene microfibers were prepared by meltblowing the aforementioned composite resin using a meltblown spinning machine from Tuoren Group. The screw compression and homogenization sections were set to temperatures of 120–240°C, the meltblown assembly temperature to 240°C, the hot air temperature to 230°C, the hot air frequency to 50Hz, and the receiving distance to 20cm, resulting in meltblown polyethylene microfiber nonwoven material. The diameter of the meltblown microfiber nonwoven material was mainly 1–3 μm, with a small amount of coarse fibers ranging from 4–10 μm. The transverse and longitudinal tensile strengths of the microfiber nonwoven material reached 5.7 ± 0.15 N and 5.4 ± 0.13 N, respectively.

[0082] 3) Polyethylene nonwoven materials:

[0083] The above-mentioned meltblown microfibers were combined with spunbond polyethylene nonwoven fabric to obtain polyethylene nonwoven material. When used to prepare face masks, the basis weight ratio of the spunbond layer to the meltblown layer was controlled at 30–50:5–10, achieving a filtration efficiency of 97% and a resistance of <200 Pa. Protective clothing was also prepared based on spunbond polyethylene nonwoven fabric and the above-mentioned meltblown microfibers, with the basis weight ratio of the spunbond layer to the meltblown layer controlled at 30–50:3–5. The transverse and longitudinal tensile strength of the protective clothing was greater than 62 N.

[0084] Example 3

[0085] 1) Twin-screw extruder for preparing composite resins:

[0086] 15 kg of polyethylene powder with a melt index of 600 g / 10 min, 85 kg of polyethylene powder with a melt index of 1500 g / 10 min, 0.05 kg of dicumyl peroxide, and 0.1 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol) were thoroughly mechanically premixed and then added to a twin-screw extruder for reactive extrusion to obtain a composite resin. The temperature of the screw feed section to the homogenization section was set at 110–140 °C, and the screw speed was 75 rpm.

[0087] 2) Meltblown polyethylene microfiber nonwoven material:

[0088] Polyethylene microfibers were prepared by meltblowing the aforementioned composite resin using a meltblown spinning machine from Tuoren Group. The screw compression and homogenization sections were set to temperatures of 120–240°C, the meltblown assembly temperature to 230°C, the hot air temperature to 210°C, the hot air frequency to 40Hz, and the receiving distance to 35cm, resulting in meltblown polyethylene microfiber nonwoven material. The diameter of the meltblown microfiber nonwoven material was mainly 1–2 μm, with a small amount of coarse fibers of 5–9 μm. The transverse and longitudinal tensile strengths of the microfiber nonwoven material reached 5 ± 0.13 N and 4.5 ± 0.17 N, respectively.

[0089] 3) Polyethylene nonwoven materials:

[0090] The above-mentioned meltblown microfibers were combined with spunbond polyethylene nonwoven fabric to obtain polyethylene nonwoven material. When used to prepare face masks, the basis weight ratio of the spunbond layer to the meltblown layer was controlled at 30–50:5–10, achieving a filtration efficiency of 96% and a resistance of <220 Pa. Protective clothing was also prepared based on spunbond polyethylene nonwoven fabric and the above-mentioned meltblown microfibers, with the basis weight ratio of the spunbond layer to the meltblown layer controlled at 30–50:3–5. The transverse and longitudinal tensile strength of the protective clothing was greater than 65 N.

[0091] Example 4

[0092] 1) Twin-screw extruder for preparing composite resins:

[0093] 20 kg of polyethylene powder with a melt index of 200 g / 10 min, 80 kg of polyethylene powder with a melt index of 1200 g / 10 min, 0.01 kg of dicumyl peroxide, and 0.2 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol) were thoroughly mechanically premixed and then added to a twin-screw extruder for reactive extrusion to obtain a composite resin. The temperature of the screw feed section to the homogenization section was set at 110–140 °C, and the screw speed was 85 rpm.

[0094] 2) Meltblown polyethylene microfiber nonwoven material:

[0095] Polyethylene microfibers were prepared by meltblowing the aforementioned composite resin using a meltblown spinning machine from Tuoren Group. The screw compression and homogenization sections were set to temperatures of 120–210°C, the meltblown assembly temperature to 210°C, the hot air temperature to 250°C, the hot air frequency to 45Hz, and the receiving distance to 30cm, resulting in meltblown polyethylene microfiber nonwoven material. The diameter of the meltblown microfiber nonwoven material was mainly 1–3 μm, with a small amount of coarse fibers ranging from 4–9 μm. The transverse and longitudinal tensile strengths of the microfiber nonwoven material reached 5.7 ± 0.22 N and 5.5 ± 0.15 N, respectively.

[0096] 3) Polyethylene nonwoven materials:

[0097] The above-mentioned meltblown microfibers were combined with spunbond polyethylene nonwoven fabric to obtain polyethylene nonwoven material. When used to prepare face masks, the basis weight ratio of the spunbond layer to the meltblown layer was controlled at 30–50:5–10, achieving a filtration efficiency of 95% and a resistance of <220 Pa. Protective clothing was also prepared based on spunbond polyethylene nonwoven fabric and the above-mentioned meltblown microfibers, with the basis weight ratio of the spunbond layer to the meltblown layer controlled at 30–50:3–5. The transverse and longitudinal tensile strength of the protective clothing was greater than 66 N.

[0098] Comparative Example 1

[0099] 1) Twin-screw resin preparation:

[0100] 100 kg of polyethylene powder with a melt index of 200 g / 10 min was added to a twin-screw extruder and extruded to obtain resin that had undergone one treatment. The temperature of the screw feed section to the homogenization section was set at 110–140 °C, and the screw speed was 50 rpm.

[0101] 2) Meltblown polyethylene microfiber nonwoven material:

[0102] Polyethylene microfibers were prepared by meltblowing the above-treated resin using a meltblown spinning machine from Tuoren Group. The screw compression and homogenization sections were set to temperatures of 120–240°C, the meltblown assembly temperature to 240°C, the hot air temperature to 260°C, the hot air frequency to 45Hz, and the receiving distance to 35cm. This yielded meltblown polyethylene microfiber nonwoven material with a diameter primarily ranging from 1 to 1.8 μm. The transverse and longitudinal tensile strengths of the microfiber nonwoven material reached 4.4 ± 0.15 N and 4.2 ± 0.16 N, respectively.

[0103] 3) Polyethylene nonwoven materials:

[0104] The above-mentioned meltblown microfibers were combined with spunbond polyethylene nonwoven fabric to obtain polyethylene nonwoven material. When used to prepare face masks, the spunbond / meltblown layer basis weight ratio was controlled at 30–50:5–10, achieving a filtration efficiency of 94% and a resistance of <210 Pa. Protective clothing was also prepared based on spunbond polyethylene nonwoven fabric and the above-mentioned meltblown microfibers, with the spunbond / meltblown layer basis weight ratio controlled at 30–50:3–5, achieving a transverse and longitudinal tensile strength of 62 N.

[0105] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A high-filtration polyethylene nonwoven material, characterized in that, It includes a spunbond layer and a meltblown layer. The meltblown layer is formed by meltblowing a first high melt index polyethylene, a second high melt index polyethylene, and a spinning aid. The melt index of the first high melt index polyethylene is 200~600 g / 10min, and the melt index of the second high melt index polyethylene is 1000~1500 g / 10min. The spinning aid is at least one of dicumyl peroxide and 4,4'-thiobis(6-tert-butyl-3-methylphenol).

2. The high-filtration polyethylene nonwoven material according to claim 1, characterized in that, The mass ratio of the first high melt index polyethylene to the second high melt index polyethylene is 5~20: 80~95.

3. The high-filtration polyethylene nonwoven material according to claim 1, characterized in that, The spunbond layer is a polyethylene spunbond layer.

4. The high-filtration polyethylene nonwoven material according to claim 1, characterized in that, The mass of the dicumyl peroxide is 0.01 to 0.2% of the sum of the masses of the first high melt index polyethylene and the second high melt index polyethylene, and the mass of the 4,4'-thiobis(6-tert-butyl-3-methylphenol) is 0.1 to 0.2% of the sum of the masses of the first high melt index polyethylene and the second high melt index polyethylene.

5. The high-filtration polyethylene nonwoven material according to claim 1, characterized in that, The high-filtration polyethylene nonwoven material has a transverse and longitudinal tensile strength ≥55N, a filtration efficiency of 95%~97%, and a resistance <220Pa.

6. A method for preparing a high-filtration polyethylene nonwoven material, characterized in that, The high-filtration polyethylene nonwoven material comprises a spunbond layer and a meltblown layer, and its preparation method includes: Step 1: Mix and granulate the first high melt index polyethylene, the second high melt index polyethylene, and the spinning aid; Step 2: The resin obtained in Step 1 is melt-blown spun to obtain a melt-blown layer; Step 3: Composite the spunbond layer with the meltblown layer to obtain a high-filtration polyethylene nonwoven material; Wherein, the melt index of the first high melt index polyethylene is 200~600 g / 10min, and the melt index of the second high melt index polyethylene is 1000~1500 g / 10min; the spinning aid is at least one of dicumyl peroxide and 4,4'-thiobis(6-tert-butyl-3-methylphenol).

7. The method for preparing the high-filtration polyethylene nonwoven material according to claim 6, characterized in that, The mass ratio of the first high melt index polyethylene to the second high melt index polyethylene is 5~20: 80~95.

8. The method for preparing the high-filtration polyethylene nonwoven material according to claim 6, characterized in that, The mass of the dicumyl peroxide is 0.01 to 0.2% of the sum of the masses of the first high melt index polyethylene and the second high melt index polyethylene, and the mass of the 4,4'-thiobis(6-tert-butyl-3-methylphenol) is 0.1 to 0.2% of the sum of the masses of the first high melt index polyethylene and the second high melt index polyethylene.

9. The method for preparing the high-filtration polyethylene nonwoven material according to claim 6, characterized in that, Step 2 is performed in a meltblown spinning machine with a screw temperature of 210~240°C. o C, Hot air temperature is 230~260 o C, hot air frequency is 40-50Hz, receiving distance is 20~35 cm.

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