Polytetrafluoroethylene porous membrane base fabric and preparation method and application in medical protective clothing field

Abstract

The present application relates to the field of polytetrafluoroethylene filter material, and more particularly to a polytetrafluoroethylene porous membrane base fabric, a preparation method and application in the field of medical protective clothing. The polytetrafluoroethylene porous membrane base fabric comprises a polytetrafluoroethylene porous membrane and outer layer fabric compounded on both sides of the polytetrafluoroethylene porous membrane; wherein the polytetrafluoroethylene porous membrane comprises component A and component B; the component A and the component B are both polytetrafluoroethylene resins and the average relative standard density of each is between 2.1-2.2 g / cm 3 The average relative standard density of the component A is greater than that of the component B. The polytetrafluoroethylene porous membrane base fabric has high barrier efficiency, good air permeability, good moisture permeability and high reusability, and is particularly suitable as medical protective clothing fabric.

Description

Technical Field

[0001] This invention relates to the field of polytetrafluoroethylene (PTFE) filter materials, and more specifically, to a PTFE porous membrane-based fabric, its preparation method, and its application in the field of medical protective clothing. Background Technology

[0002] In infectious disease prevention and control, such as after the outbreak of COVID-19, especially in the early stages of the epidemic, the huge consumption and long production cycle of traditional disposable medical protective clothing led to supply shortages, and the only solution was incineration, which caused serious environmental problems. In response to similar large-scale public health crises, medical protective products that can be stored for a long time and are reusable are more advantageous, and polytetrafluoroethylene porous membranes are a material that can meet the above requirements.

[0003] Polytetrafluoroethylene (PTFE) porous membranes are thin films made from PTFE resin through a special stretching process. Their microstructure consists of a network of entangled microfibers, with countless micropores formed between the fibers. PTFE porous membranes retain the excellent properties of PTFE and also possess advantages such as large specific surface area, high porosity, good air permeability, high inertness, non-toxicity, and non-allergenicity. In particular, PTFE porous membrane materials have high filtration efficiency with minimal degradation and can be reused after washing, making them excellent medical and hygiene protective filter materials. However, PTFE porous membranes rely solely on physical retention to achieve high-efficiency filtration, often making it difficult to simultaneously achieve both barrier efficiency and air / moisture permeability. This is especially true when used as fabric after being laminated with other materials, where the resulting fabric's air / moisture permeability is further significantly reduced.

[0004] Currently, the technical problem that needs to be solved is to provide a reusable polytetrafluoroethylene fabric with excellent moisture permeability and high barrier efficiency. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a polytetrafluoroethylene (PTFE) porous membrane-based fabric, its preparation method, and its application in the field of medical protective clothing. This PTFE porous membrane-based fabric exhibits high barrier efficiency, good air permeability, and good moisture permeability. Furthermore, the PTFE porous membrane-based fabric of this invention retains its original excellent properties after multiple washes, demonstrating high reusability and making it particularly suitable as a medical protective clothing fabric.

[0006] The first objective of this invention is to provide a polytetrafluoroethylene (PTFE) porous membrane-based fabric, comprising a PTFE porous membrane and an outer fabric laminated on both sides of the PTFE porous membrane; wherein the PTFE porous membrane is prepared by the following PTFE composite:

[0007] The polytetrafluoroethylene composite includes component A, component B, and an extrusion aid; components A and B are both polytetrafluoroethylene resins, and their respective average relative standard densities are both between 2.1 and 2.2 g / cm³. 3 Between these two points, the average relative standard density of component A is greater than the average relative standard density of component B.

[0008] In a preferred embodiment of the present invention, the average relative standard density of component A is 2.161-2.2 g / cm³. 3 .

[0009] In a preferred embodiment of the present invention, the average relative standard density of component B is 2.13-2.160 g / cm³. 3 .

[0010] In a preferred embodiment of the present invention, the thermal instability coefficients of component A and component B are each not greater than 50.

[0011] According to the present invention, the selection range of the formulation is relatively wide. In a preferred embodiment of the present invention, based on 100 wt% of the total weight of the polytetrafluoroethylene composite, the content of component A is 5-90 wt%, the content of component B is 5-90 wt%, and the content of the extrusion aid is 5-50 wt%. More preferably, based on 100 wt% of the total weight of the polytetrafluoroethylene composite, the content of component A is 10-50 wt%, the content of component B is 30-70 wt%, and the content of the extrusion aid is 5-30 wt%.

[0012] According to the present invention, based on the total weight of the polytetrafluoroethylene composite of 100 wt%, the content of component A is 5-90 wt%, preferably 10-50 wt%, for example, it can be 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, and any value between 10 wt% and 50 wt%, and any range of any two values.

[0013] According to the present invention, based on the total weight of the polytetrafluoroethylene composite of 100 wt%, the content of component B is 5-90 wt%, preferably 30-70 wt%, for example, it can be 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, and any value between 30 wt% and 70 wt%, and any range of any two values.

[0014] According to the present invention, based on the total weight of the polytetrafluoroethylene composite of 100 wt%, the content of the extrusion aid is 5-50 wt%, preferably 5-30 wt%, for example, it can be 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, and any value between 5 wt% and 30 wt%, and any range between any two values.

[0015] In a preferred embodiment of the present invention, component A and component B are each independently selected from polytetrafluoroethylene resin obtained by dispersion polymerization.

[0016] The extrusion aid can be selected from a variety of options. In a preferred embodiment of the present invention, the extrusion aid is selected from at least two of aviation kerosene, white oil, naphtha, isoalkanes, and kerosene. Preferably, the extrusion aid is selected from at least two of aviation kerosene, white oil, and isoalkanes. More preferably, the extrusion aid is selected from aviation kerosene and isoalkanes, wherein, based on the total weight of the extrusion aid as 100%, the content of aviation kerosene is 10-50 wt%, and the content of isoalkanes is 50-90 wt%.

[0017] In a preferred embodiment of the present invention, the filtration efficiency of the polytetrafluoroethylene porous membrane in saline media is not less than 95%.

[0018] In a preferred embodiment of the present invention, the polytetrafluoroethylene porous membrane is subjected to a pressure of 7 kPa and a test area of ​​20 cm². 2 The air permeability under the given conditions is 2-10 L / min, preferably 2-5 L / min.

[0019] In a preferred embodiment of the present invention, the polytetrafluoroethylene porous membrane is prepared by a method comprising the following steps:

[0020] (1) Mix the components including component A, component B and extrusion aid to obtain the polytetrafluoroethylene composite.

[0021] (2) The polytetrafluoroethylene composite is then used to form a membrane to obtain the polytetrafluoroethylene porous membrane.

[0022] In a preferred embodiment of the present invention, the mixing is carried out under pressure, preferably 0.2-10 MPa; and / or the mixing time is 10-150 h.

[0023] In a preferred embodiment of the present invention, the mixing method is non-stirring mixing, preferably by rotating the container to mix the materials inside the container, preferably at a speed of 10-200 rpm.

[0024] In a preferred embodiment of the present invention, the mixing process includes a settling period, preferably 10-20 hours; and / or a settling temperature of 40-80°C.

[0025] In a preferred embodiment of the present invention, the film-forming process of the polytetrafluoroethylene composite preferably includes preforming, extrusion, calendering, biaxial stretching, heat setting, and then cooling of the polytetrafluoroethylene composite.

[0026] In a more preferred embodiment of the present invention, the process includes mixing the raw materials of the polytetrafluoroethylene composite (component A, component B and extrusion aid) under pressure, then allowing it to stand, followed by preforming, extrusion, calendering, synchronous or asynchronous biaxial stretching, heat setting, and then cooling.

[0027] In a preferred embodiment of the present invention, the mixing conditions under pressure include: a pressure of 0.2-10 MPa, preferably 0.2-3 MPa; and / or a time of 10-150 h, preferably 30-150 h. According to the present invention, the mixing method can be selected from various options. Preferably, a non-stirring mixing method is used; more preferably, a container drives the material to rotate for mixing; and even more preferably, a low-speed drum is used as the mixing means. The rotational speed has a wide selection range, preferably 10-200 rpm.

[0028] According to the present invention, the selection range of standing conditions is relatively wide. In a preferred embodiment of the present invention, the standing conditions include: a time of 10-20 hours and / or a temperature of 40-80°C.

[0029] According to the present invention, the selection range of the preforming conditions is relatively wide. In a preferred embodiment of the present invention, the preforming is performed with a preforming pressure of 5-50 MPa and a holding time of 10s-10min.

[0030] According to the present invention, the range of conditions for the push extrusion is relatively wide. In a preferred embodiment of the present invention, the compression ratio of the push extrusion is 10-200, preferably 10-30.

[0031] According to the present invention, the selection range of the rolling conditions is relatively wide. In a preferred embodiment of the present invention, the rolling pressure is 0.1-10 MPa, preferably 0.5-5 MPa.

[0032] According to the present invention, the range of stretching conditions is relatively wide. In a preferred embodiment of the present invention, bidirectional stretching is performed by simultaneously performing longitudinal and transverse stretching. Preferably, the stretching temperature is 20-300℃, and more preferably 150-250℃.

[0033] In a preferred embodiment of the present invention, the bidirectional stretching is performed asynchronously by longitudinal stretching and transverse stretching; preferably, the stretching temperature is 20-300℃, more preferably 150-250℃.

[0034] According to the present invention, the range of heat setting conditions is relatively wide. In a preferred embodiment of the present invention, the heat setting temperature is 300-380°C and the heat setting time is 20-300 seconds.

[0035] According to the present invention, the cooling conditions can be selected over a wide range. In a preferred embodiment of the present invention, the cooling rate is 5-100°C / min.

[0036] In a more preferred embodiment of the present invention, the method for preparing a polytetrafluoroethylene (PTFE) porous membrane includes mixing, preforming, extruding, calendering, synchronous / asynchronous biaxial stretching, heat setting, and cooling of the PTFE composite raw materials under pressure conditions to obtain a PTFE porous membrane; wherein the mixing under pressure conditions is 0.2-10 MPa, the standing time is 10-20 h, and the temperature is 40-80 °C; the preforming is performed by mixing the components of the PTFE composite under a preforming pressure of 5-50 MPa and holding pressure. The time is 10s-10min; the compression ratio of the extrusion is 10-200; the calendering pressure is 0.1-10MPa; the synchronous biaxial stretching is the simultaneous longitudinal and transverse stretching at a stretching temperature of 20-300℃; the asynchronous biaxial stretching is the sequential longitudinal and transverse stretching at a stretching temperature of 20-300℃; the heat setting temperature is 300-380℃ and the heat setting time is 20-300 seconds; the cooling rate is 5-100℃ per minute until room temperature is reached.

[0037] According to the present invention, the polytetrafluoroethylene porous membrane-based fabric is a sandwich-type fabric, comprising an intermediate layer formed of a polytetrafluoroethylene porous membrane and an outer layer fabric laminated on both sides of the intermediate layer.

[0038] In a more preferred embodiment of the present invention, the outer fabric is a polyester fiber fabric, preferably a chemically modified polyester fiber fabric, and more preferably a chemically modified polyester fiber fabric with an uneven cross section. The above polyester fiber fabrics are conventional commercially available products in clothing fabrics, including but not limited to the models used in the embodiments of the present invention.

[0039] In a more preferred embodiment of the present invention, the composite method is to use an adhesive for bonding. Preferably, the adhesive is distributed in dots, and / or the adhesive used is a polyurethane hot melt adhesive, preferably a moisture-curing reactive polyurethane hot melt adhesive. Preferably, the total area covered by the adhesive dots on one side is not higher than 60% of the surface area of ​​the polytetrafluoroethylene porous membrane on one side, and more preferably, the total area covered by the adhesive dots on one side is not higher than 40% of the surface area of ​​the polytetrafluoroethylene porous membrane on one side.

[0040] In a more preferred embodiment of the present invention, the filtration efficiency of the polytetrafluoroethylene porous membrane-based fabric is not less than 90%; and / or, the moisture permeability is not less than 4000 g / (m²). 2 *d); and / or, resistance to blood penetration is not lower than level 2; and / or, hydrostatic pressure is not less than 5 kPa.

[0041] In a more preferred embodiment of the present invention, after the polytetrafluoroethylene porous membrane-based fabric is washed and disinfected 20 times according to standard WS / T 508-2016: the filtration efficiency of the polytetrafluoroethylene porous membrane-based fabric is not less than 90%; and / or, the moisture permeability is not less than 3000 g / (m²). 2 *d); and / or, resistance to blood penetration is not lower than level 2; and / or, hydrostatic pressure is not less than 5 kPa.

[0042] The second objective of this invention is to provide a method for preparing the polytetrafluoroethylene porous membrane-based fabric described in the first objective, comprising the steps of sequentially applying adhesive, laminating an outer layer fabric, and curing on both sides of the polytetrafluoroethylene porous membrane.

[0043] Thus, by sequentially applying adhesive, composite outer fabric, and curing on both sides of the polytetrafluoroethylene porous membrane, a sandwich-type fabric is formed with the polytetrafluoroethylene porous membrane as the middle layer and the outer fabric on both sides.

[0044] The adhesive can be applied using a textured roller or a dot-coating roller. In a preferred embodiment of the present invention, the adhesive is applied using a dot-coating roller, and the adhesive is applied in a laminating machine; and / or, the total area covered by adhesive dots on one side is not higher than 60% of the surface area of ​​the polytetrafluoroethylene porous membrane on one side, preferably, the total area covered by adhesive dots on one side is not higher than 40% of the surface area of ​​the polytetrafluoroethylene porous membrane on one side.

[0045] The adhesive used is preferably a polyurethane hot melt adhesive, more preferably a moisture-curing reactive polyurethane hot melt adhesive, and is a conventional commercially available product, including but not limited to Henke's Technomelt PUR 7500 series products and HB Fuller's Full-Care. 5000 series products. There is no particular limitation on the amount of adhesive used; use it according to the general requirements of commercially available adhesives. Similarly, there are no specific requirements for the curing conditions; simply follow the instructions for use of the conventional adhesive.

[0046] The third objective of this invention is to provide an application of the polytetrafluoroethylene porous membrane-based fabric described in the first objective or the polytetrafluoroethylene porous membrane-based fabric prepared by the preparation method described in the second objective as a medical protective clothing fabric.

[0047] As described above, compared with the prior art, the polytetrafluoroethylene porous membrane-based fabric of the present invention has high filtration efficiency, high moisture permeability, high blood penetration resistance, and high hydrostatic pressure. Furthermore, it retains its original properties after multiple washes, making it highly suitable as a medical protective clothing fabric. It significantly improves both the effectiveness of medical prevention and control and the user experience for medical workers, demonstrating extremely high application value. The specific advantages of the present invention are:

[0048] (1) By using a mixture of two preferred polytetrafluoroethylene resins with relatively standard densities, the product exhibits composite characteristics, combining the advantages of high barrier efficiency and good air permeability. The inventors of this invention believe that the above advantages are due to the fact that the different raw materials have different tensile properties and microstructures under the same conditions. During the same stretching process, the two components of polytetrafluoroethylene exhibit differentiated tensile properties, forming different fiber structures, resulting in a porous membrane with a composite structure.

[0049] (2) The present invention preferably uses a specific composite extrusion aid and two polytetrafluoroethylene raw materials with different densities to prepare the composite extrusion aid. The composite extrusion aid promotes the compatibility of the two different polytetrafluoroethylene resins, resulting in a composite material with the above advantages, taking into account both economy and functionality.

[0050] (3) The present invention uses a specific method to mix the raw materials under pressure conditions, thereby obtaining the composite material with the above advantages. This may be because mixing under pressure conditions improves and accelerates the mixing of the extrusion aid and polytetrafluoroethylene resin, resulting in a composite material with composite properties.

[0051] (4) The composite material obtained by the method of the present invention has a salt medium filtration efficiency of up to 97% and an air permeability of about 3L / min, which has the advantages of high barrier efficiency and good air permeability.

[0052] (5) The medical protective clothing fabric obtained by the method of the present invention has a filtration efficiency of not less than 90% and a moisture permeability of not less than 4000 g / (m²). 2 *d), which has the characteristics of high barrier efficiency and good moisture permeability.

[0053] (6) The medical protective clothing fabric obtained by the method of the present invention has a filtration efficiency of not less than 90% and a moisture permeability of not less than 3000 g / (m²) after 20 washes and disinfections. 2 *d), still has the characteristics of high barrier efficiency and good moisture permeability. Attached Figure Description

[0054] Figure 1 , Figure 2 , Figure 3 This is a scanning electron microscope image of the cross-section of the polytetrafluoroethylene porous membrane-based fabric prepared in Example 2. Figure 2 for Figure 1 Enlarged photo, Figure 3 for Figure 2 Enlarged photo.

[0055] As can be seen, the fabric of the present invention has a typical sandwich structure, with an outer layer of fiber fabric, a middle layer of polytetrafluoroethylene porous membrane, a discontinuous adhesive layer between the fiber fabric and the polytetrafluoroethylene porous membrane, and an irregular cross-section of the fiber. Detailed Implementation

[0056] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0057] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0058] (1) Experimental equipment: The stretching equipment was a German Bruckner biaxial stretching machine.

[0059] (2) Instruments used for experimental data determination: The relative standard density in the experiment was determined in accordance with GB / T 1033.1. Electron microscope images were taken using a Hitachi S4800-SEM and a COXEM EM-30AX. + Filming.

[0060] In the following embodiments, some of the raw materials of the present invention are described in the embodiments. Unless otherwise specified, other raw materials are conventional commercial products.

[0061] Example 1

[0062] 1 kg of polytetrafluoroethylene resin (Sichuan Chenguang CGF216G, average relative standard density 2.162), 1 kg of polytetrafluoroethylene resin (Sichuan Chenguang CGF216Y, average relative standard density 2.15), 0.1 kg of naphtha, and 0.4 kg of isoparaffin (ExxonMobil Isopar G) were mixed at 0.5 MPa for 50 h (50 rpm rotating the sealed container for 50 h to ensure thorough mixing of the resin powder and extrusion aid), and then allowed to stand at 40 °C for 20 h to obtain the polytetrafluoroethylene composite.

[0063] The above-mentioned polytetrafluoroethylene (PTFE) composite was subjected to the following processes to prepare a porous PTFE membrane: preforming (pressure 5 MPa, holding time 30 s), extrusion (compression ratio 25), calendering (pressure 3 MPa), asynchronous biaxial stretching (longitudinal stretching temperature 200 °C, transverse stretching temperature 70 °C), heat setting (temperature 340 °C, duration 30 s), and cooling (cooling rate 30 °C per minute). Specific test results are shown in Table 1.

[0064] The above-mentioned polytetrafluoroethylene (PTFE) porous membrane was coated with adhesive (Technomelt PUR7585 hot melt polyurethane adhesive was applied in a dotted pattern, with the total area of ​​the adhesive dots covering 25% of the surface area of ​​one side of the PTFE porous membrane), and then laminated with an outer fabric (the outer fabric is a modified polyester fiber fabric with embedded polyether segments, fiber specification 30DDTY), and cured to obtain a PTFE porous membrane base fabric. Specific test results are shown in Table 2.

[0065] Example 2

[0066] 1 kg of polytetrafluoroethylene resin (Shandong Dongyue DF205, average relative standard density 2.165), 1 kg of polytetrafluoroethylene resin (DuPont 605xt, average relative standard density 2.16), 0.1 kg of aviation kerosene (3#), and 0.1 kg of isoparaffin (ExxonMobil Isopar G) were mixed at 0.5 MPa for 30 h (the sealed container was rotated at 50 rpm for 30 h to ensure thorough mixing of the resin powder and extrusion aid), and then allowed to stand at 40 °C for 10 h to obtain the polytetrafluoroethylene composite.

[0067] The above-mentioned polytetrafluoroethylene composite was subjected to a series of processes to prepare a polytetrafluoroethylene porous membrane, including preforming (pressure 30 MPa, holding time 3 min), extrusion (compression ratio 50), calendering (pressure 10 MPa), simultaneous biaxial stretching (stretching temperature 250℃), heat setting (temperature 380℃, duration 20 seconds), and cooling (cooling rate 50℃ per minute).

[0068] The above-mentioned polytetrafluoroethylene porous membrane is coated with adhesive (Technomelt PUR7585 polyurethane hot melt adhesive is applied in a dot pattern, and the total area covered by the adhesive dots on one side is 28% of the surface area of ​​the polytetrafluoroethylene porous membrane on one side), and then composited with an outer layer fabric (the outer layer fabric is a modified polyester fiber fabric with embedded polyether segments and the fiber specification is 30DDTY), and cured to obtain a polytetrafluoroethylene porous membrane base fabric.

[0069] Example 3

[0070] 1 kg of polytetrafluoroethylene resin (Sichuan Chenguang CGF216G, average relative standard density 2.162), 4 kg of polytetrafluoroethylene resin (DuPont 605xt, average relative standard density 2.16), 0.1 kg of aviation kerosene (3#), and 0.1 kg of isoparaffin (ExxonMobil Isopar G) were mixed at 0.5 MPa for 150 h (the sealed container was rotated at 50 rpm for 150 h to ensure thorough mixing of the resin powder and extrusion aid), and then allowed to stand at 80 °C for 10 h to obtain the polytetrafluoroethylene composite.

[0071] The above-mentioned polytetrafluoroethylene composite was subjected to a series of processes to prepare a polytetrafluoroethylene porous membrane, including preforming (pressure 10 MPa, holding time 1 min), extrusion (compression ratio 20), calendering (pressure 5 MPa), simultaneous biaxial stretching (stretching temperature 150℃), heat setting (temperature 300℃, duration 60 seconds), and cooling (cooling rate 30℃ per minute).

[0072] Following the method of Example 2, the polytetrafluoroethylene porous membrane of this example is composited with an outer fabric to obtain polytetrafluoroethylene porous membrane base fabric.

[0073] Example 4

[0074] 1 kg of polytetrafluoroethylene resin (Shanghai Sanaifu FR203A-2, average relative standard density 2.18), 2 kg of polytetrafluoroethylene resin (Japan Daikin F106, average relative standard density 2.158), 0.4 kg of aviation kerosene (5#), and 0.1 kg of isoparaffin (ExxonMobil Isopar M) were mixed at 0.2 MPa for 120 h (the sealed container was rotated at 50 rpm for 120 h to ensure thorough mixing of the resin powder and extrusion aid), and then allowed to stand at 80 °C for 20 h to obtain the polytetrafluoroethylene composite.

[0075] The above-mentioned polytetrafluoroethylene composite was subjected to the following processes to prepare a polytetrafluoroethylene porous membrane: preforming (pressure 50 MPa, holding time 10 s), extrusion (compression ratio 10), calendering (pressure 0.5 MPa), asynchronous biaxial stretching (longitudinal stretching temperature 250 degrees Celsius, transverse stretching temperature 150 degrees Celsius), heat setting (temperature 300 degrees Celsius, duration 300 seconds), and cooling (cooling rate 15 degrees Celsius per minute).

[0076] Following the method of Example 1, the polytetrafluoroethylene porous membrane of this example is composited with an outer fabric to obtain polytetrafluoroethylene porous membrane base fabric.

[0077] Example 5

[0078] 3 kg of polytetrafluoroethylene resin (Shandong Dongyue DF205, average relative standard density 2.165), 1 kg of polytetrafluoroethylene resin (Sichuan Chenguang CGF216Y, average relative standard density 2.15), 0.8 kg of white oil (3#), and 1.2 kg of aviation kerosene (3#) were mixed at 2 MPa for 100 h (the sealed container was rotated at 50 rpm for 100 h to ensure that the resin powder and extrusion aid were fully mixed), and then allowed to stand at 60 °C for 15 h to obtain a polytetrafluoroethylene composite.

[0079] The above-mentioned polytetrafluoroethylene composite was subjected to the following processes to prepare a polytetrafluoroethylene porous membrane: preforming (pressure 15 MPa, holding time 30 s), extrusion (compression ratio 15), calendering (pressure 2 MPa), asynchronous biaxial stretching (longitudinal stretching temperature 300 degrees Celsius, transverse stretching temperature 200 degrees Celsius), heat setting (temperature 320 degrees Celsius, duration 100 seconds), and cooling (cooling rate 40 degrees Celsius per minute).

[0080] Following the method of Example 1, the polytetrafluoroethylene porous membrane of this example is composited with an outer fabric to obtain polytetrafluoroethylene porous membrane base fabric.

[0081] Example 6

[0082] The polytetrafluoroethylene porous membrane-based fabric from Example 2 was washed and disinfected 20 times according to the hygiene industry standard WS / T508-2016 to obtain a reusable polytetrafluoroethylene porous membrane-based fabric.

[0083] Example 7

[0084] The polytetrafluoroethylene porous membrane-based fabric from Example 2 was washed and disinfected 20 times according to the hygiene industry standard WS / T508-2016 to obtain a reusable polytetrafluoroethylene porous membrane-based fabric.

[0085] Preparation of Comparative Example 1

[0086] 2 kg of polytetrafluoroethylene resin (DuPont 605 XT, average relative standard density 2.16) and 0.2 kg of aviation kerosene were mixed at atmospheric pressure for 50 h and then allowed to stand at 60 °C for 15 h to obtain a polytetrafluoroethylene composite. A porous polytetrafluoroethylene membrane was prepared by a series of processes including preforming (pressure 10 MPa, holding time 1 min), extrusion (compression ratio 20), calendering (pressure 5 MPa), simultaneous biaxial stretching (stretching temperature 150 °C), heat setting (temperature 300 °C, duration 60 s), and cooling (cooling rate 30 °C per minute).

[0087] Preparation of Comparative Example 2

[0088] Two kilograms of polytetrafluoroethylene (PTFE) resin (Shandong Dongyue DF205, average relative standard density 2.165) and 0.6 kilograms of isoparaffin (ExxonMobil Isopar G) were mixed at normal pressure for 80 hours and then allowed to stand at 80°C for 10 hours to obtain a PTFE composite. A porous PTFE membrane was prepared by a series of processes including preforming (pressure 10 MPa, holding time 1 min), extrusion (compression ratio 20), calendering (pressure 5 MPa), asynchronous biaxial stretching (longitudinal stretching temperature 300°C, transverse stretching temperature 150°C), heat setting (temperature 300°C, duration 60 seconds), and cooling (cooling rate 30°C per minute).

[0089] Preparation of Comparative Example 3

[0090] The polytetrafluoroethylene (PTFE) composite was prepared according to the method of Example 1, except that it was mixed at normal pressure for 30 hours and then allowed to stand at 40°C for 10 hours to obtain the PTFE composite. A porous PTFE membrane was then prepared according to Example 2.

[0091] Detection example

[0092] The filtration efficiency of the porous membranes prepared in Examples 1-5 and Comparative Examples 1-3 was tested using the method in Appendix A of the national standard GB / T 32610-2016 with NaCl particles as the test medium and a flow rate of 85 L / min. The air permeability of the prepared porous membranes was tested using the method in GB / T 5453-1997 with a test pressure of 7 kPa and a test area of ​​20 cm². 2 The test results are shown in Table 1.

[0093] The filtration efficiency, hydrostatic pressure, moisture permeability, and resistance to synthetic blood penetration of the medical protective clothing fabrics prepared in Examples 1-7 were tested according to the national standard GB 19082-2009. The test results are shown in Table 2.

[0094] Table 1

[0095] Sample number Salt media filtration efficiency (%) Air permeability (L / min) Example 1 96.9 2.7 Example 2 97.5 3.1 Example 3 96.8 2.6 Example 4 97.3 2.8 Example 5 96.7 2.4 Preparation of Comparative Example 1 85.5 5.1 Preparation of Comparative Example 2 97.3 1.7 Preparation of Comparative Example 3 96.5 2.2

[0096] Table 2

[0097] Test Project Example 2 Example 6 Example 1 Example 7 Hydrostatic pressure (kPa) ﹥10.0 ﹥10.0 ﹥10.0 ﹥10.0 <![CDATA[Water vapor transmission rate (g / (m 2 *d))]]> 6340 4360 5640 3980 Resistance to synthetic blood penetration (grade) ﹥4 ﹥4 ﹥4 ﹥4 Filtration efficiency (%) ﹥90 ﹥90 ﹥90 ﹥90

[0098] As shown in Table 1, the filtration efficiency of the polytetrafluoroethylene porous membrane in the embodiments of the present invention in saline media is not less than 95%; at a pressure of 7 kPa and a test area of ​​20 cm², the filtration efficiency is as follows: 2 The air permeability under all conditions is greater than 2.2 L / min. It is evident that the porous membrane obtained by using polytetrafluoroethylene resin raw materials of two densities in this invention contains fibers of two different diameters, thus achieving a balance between air permeability and barrier effect.

[0099] As shown in Table 2, the filtration efficiency of the polytetrafluoroethylene porous membrane-based fabric in the embodiments of the present invention is not less than 90%, and the moisture permeability is not less than 4000 g / (m²). 2 *d); After 20 washes and disinfections, the filtration efficiency is higher than 90%, and the moisture permeability is greater than 3000g / (m³). 2 *d). It is evident that the polytetrafluoroethylene porous membrane-based fabric obtained by this invention can be used as a reusable medical protective clothing fabric.

[0100] Examples 3-5 were evaluated using the same method as described in the national standard GB 19082-2009. The hydrostatic pressure, resistance to synthetic blood penetration, and filtration efficiency levels of Examples 3-5 were no different from Examples 1 and 2, all exhibiting hydrostatic pressure > 10.0 kPa, blood penetration resistance > 4 levels, and filtration efficiency > 90%. The only difference was in the moisture permeability. Example 3 was slightly lower than Example 1, at 5500 g / (m³). 2 *d); Example 4 is between Examples 1 and 2, with a content of 5880 g / (m 2 *d); Example 5 is 5030g / (m 2 *d).

[0101] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0102] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0103] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0104] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0105] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0106] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination to be obviously unreasonable.

Claims

1. A polytetrafluoroethylene (PTFE) porous membrane-based fabric, wherein the PTFE porous membrane-based fabric comprises a PTFE porous membrane and an outer fabric laminated on both sides of the PTFE porous membrane; wherein, The polytetrafluoroethylene porous membrane was prepared by the following polytetrafluoroethylene composite: The polytetrafluoroethylene composite includes component A, component B, and an extrusion aid. Both component A and component B are polytetrafluoroethylene resins, and their average relative standard densities are both between 2.1 and 2.2 g / cm³. 3 Between them, the average relative standard density of component A is greater than the average relative standard density of component B; The polytetrafluoroethylene composite is prepared by mixing the components, including component A, component B and extrusion aid, to obtain the polytetrafluoroethylene composite. The mixing is carried out under pressure.

2. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: The average relative standard density of component A is 2.161-2.2 g / cm³. 3 ; and / or, The average relative standard density of component B is 2.13-2.160 g / cm³. 3 ; and / or, The thermal instability coefficients of both component A and component B are not greater than 50.

3. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: Based on a total weight of 100 wt% for the polytetrafluoroethylene composite, the content of component A is 5-90 wt%, the content of component B is 5-90 wt%, and the content of the extrusion aid is 5-50 wt%.

4. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: Based on a total weight of 100 wt% of the polytetrafluoroethylene composite, the content of component A is 10-50 wt%, the content of component B is 30-70 wt%, and the content of the extrusion aid is 5-30 wt%.

5. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: Component A and component B are each independently selected from polytetrafluoroethylene resin obtained by dispersion polymerization; and / or, The extrusion aid is selected from at least two of aviation kerosene, white oil, naphtha, isoalkanes, and kerosene.

6. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: The extrusion aid is selected from at least two of aviation kerosene, white oil, and isoalkanes.

7. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: The extrusion aid is selected from aviation kerosene and isoalkanes.

8. The polytetrafluoroethylene porous membrane-based fabric according to claim 7, characterized in that: Based on the total weight of the extrusion aid as 100%, the content of aviation kerosene is 10-50 wt%, and the content of isoparaffins is 50-90 wt%.

9. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: The polytetrafluoroethylene porous membrane has a salt medium filtration efficiency of not less than 95%; and / or, The polytetrafluoroethylene porous membrane was tested at a pressure of 7 kPa and a test area of ​​20 cm². 2 The air permeability under the given conditions is 2-10 L / min.

10. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: The polytetrafluoroethylene porous membrane was tested at a pressure of 7 kPa and a test area of ​​20 cm². 2 The air permeability under the given conditions is 2-5 L / min.

11. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: The polytetrafluoroethylene porous membrane is prepared by a method comprising the following steps: (1) Mix the components including component A, component B and extrusion aid to obtain the polytetrafluoroethylene composite; (2) The polytetrafluoroethylene composite is then used to form a membrane to obtain the polytetrafluoroethylene porous membrane.

12. The polytetrafluoroethylene porous membrane-based fabric according to claim 11, characterized in that: In step (1): The mixing pressure is 0.2-10 MPa; and / or the mixing time is 10-150 h.

13. The polytetrafluoroethylene porous membrane-based fabric according to claim 11, characterized in that: The mixing method is non-stirring mixing.

14. The polytetrafluoroethylene porous membrane-based fabric according to claim 11, characterized in that: The mixing method involves rotating the container to mix the materials inside.

15. The polytetrafluoroethylene porous membrane-based fabric according to claim 11, characterized in that: The mixing method involves rotating the container to mix the materials inside, with a rotation speed of 10-200 rpm.

16. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: The outer fabric is made of polyester fiber.

17. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: The outer fabric is a chemically modified polyester fiber fabric.

18. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: The outer fabric is a chemically modified polyester fiber fabric with an irregular cross-section.

19. The polytetrafluoroethylene porous membrane-based fabric according to claim 1, characterized in that: The composite process involves bonding with an adhesive.

20. The polytetrafluoroethylene porous membrane-based fabric according to claim 19, characterized in that: The adhesive is distributed in dots, and / or the adhesive used is a polyurethane hot melt adhesive.

21. The polytetrafluoroethylene porous membrane-based fabric according to claim 19, characterized in that: The adhesive used is a moisture-curing reactive polyurethane hot melt adhesive.

22. The polytetrafluoroethylene porous membrane-based fabric according to any one of claims 1-21, characterized in that: The filtration efficiency of the polytetrafluoroethylene porous membrane-based fabric is not less than 90%; and / or, Moisture permeability not less than 4000g / (m²) 2 d); and / or, Blood penetration resistance not lower than grade 2; and / or, The hydrostatic pressure is not less than 5 kPa.

23. The polytetrafluoroethylene porous membrane-based fabric according to any one of claims 1-21, characterized in that: According to standard WS / T 508-2016, after washing and disinfecting the polytetrafluoroethylene porous membrane-based fabric 20 times: The filtration efficiency of the polytetrafluoroethylene porous membrane-based fabric is not less than 90%; and / or, Moisture permeability not less than 3000g / (m²) 2 d); and / or, Blood penetration resistance not lower than grade 2; and / or, The hydrostatic pressure is not less than 5 kPa.

24. A method for preparing the polytetrafluoroethylene porous membrane-based fabric according to any one of claims 1-23, comprising the steps of sequentially applying adhesive, laminating an outer layer fabric, and curing on both sides of the polytetrafluoroethylene porous membrane.

25. The preparation method according to claim 24, characterized in that: The method of applying adhesive is to apply adhesive using a dotted coating wheel; and / or, The total area covered by the adhesive dots shall not exceed 60% of the surface area of ​​the polytetrafluoroethylene porous membrane.

26. The preparation method according to claim 24, characterized in that: The total area covered by the adhesive dots shall not exceed 40% of the surface area of ​​the polytetrafluoroethylene porous membrane.

27. The application of the polytetrafluoroethylene porous membrane-based fabric according to any one of claims 1-23 or the polytetrafluoroethylene porous membrane-based fabric prepared by the preparation method according to any one of claims 24-26 as a medical protective clothing fabric.

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