Sintered PTFE composite microporous breathable film and preparation method thereof

Abstract

The invention discloses a sintered PTFE (polytetrafluoroethylene) composite microporous breathable film and a preparation method thereof. The sintered PTFE composite microporous breathable film is prepared from the following raw materials in parts by weight: 70 to 90 parts of PTFE resin, 20 to 30 parts of Ni-B-Si, 10 to 15 parts of kerosene, 5 to 20 parts of thermoplastic elastomer, 3 to 10 parts of nano filler, 0.2 to 0.6 part of initiator, 0.5 to 2 parts of dispersant and 0.1 to 0.5 part of antioxidant. By introducing various materials and optimizing the process, the PTFE composite material with a uniform microporous structure, high air permeability, excellent mechanical property and chemical corrosion resistance is prepared.

Description

Technical Field

[0001] This invention belongs to the field of PTFE membranes, specifically, it relates to a sintered PTFE composite microporous breathable membrane and its preparation method. Background Technology

[0002] Polytetrafluoroethylene (PTFE) materials have significant application value in the field of microporous membrane materials due to their unique chemical inertness, low surface energy, excellent high-temperature resistance, and good biocompatibility. PTFE microporous membranes exhibit excellent chemical stability, resisting corrosion from strong acids, strong alkalis, and organic solvents. Simultaneously, their extremely low surface energy demonstrates excellent hydrophobicity and antifouling properties. Furthermore, PTFE materials maintain stable physicochemical properties over a wide temperature range of -200℃ to 260℃, giving them a significant advantage in harsh environments. However, pure PTFE membranes have obvious limitations in practical applications: firstly, their mechanical properties are poor, exhibiting low tensile strength and elongation at break, making it difficult to meet the requirements of high-strength applications; secondly, PTFE materials have poor processing performance, and traditional preparation processes are complex, resulting in high production costs. Summary of the Invention

[0003] In view of this, the technical problem to be solved by the present invention is to provide a sintered PTFE composite microporous breathable membrane and its preparation method. By introducing a variety of materials and optimizing the process, a PTFE composite membrane with uniform microporous structure, high air permeability, excellent mechanical properties and chemical corrosion resistance is prepared, avoiding the problems of poor mechanical properties, complicated preparation process and high cost.

[0004] To address the aforementioned technical problems, this invention discloses a sintered PTFE composite microporous breathable membrane, comprising the following raw materials in parts by weight: 70-90 parts PTFE resin, 20-30 parts Ni-B-Si, 10-15 parts kerosene, 5-20 parts thermoplastic elastomer, 3-10 parts nanofiller, 0.2-0.6 parts initiator, 0.5-2 parts dispersant, and 0.1-0.5 parts antioxidant.

[0005] According to one embodiment of the present invention, the thermoplastic elastomer is polyurethane.

[0006] According to one embodiment of the present invention, the above-mentioned nanofiller is nano-silica.

[0007] According to one embodiment of the present invention, the method for preparing the above-mentioned sintered PTFE composite microporous breathable membrane is as follows: Step (1): Raw material mixing. First, PTFE resin, thermoplastic elastomer, nanofiller and initiator are cross-linked. Then, the reactants are mixed with dispersant and antioxidant and dispersed by high-speed mixer or ball mill to obtain a uniform mixture. Step (2): Pre-forming, the mixture is pre-pressed into sheet or strip blanks by calendering or extrusion, sandblasting the surface of the sheet or strip blanks, mixing Ni-B-Si and kerosene in a 2:1 ratio, and then spraying the mixture onto the surface of the sheet or strip blanks and letting it stand for a period of time. Step (3): Stretching to form holes, stretching the billet in both the longitudinal and transverse directions, stretching temperature is 100-150℃, stretching ratio is 3-8 times, forming a microporous structure; Step (4): Sintering and shaping. The stretched membrane is sintered at 300-380℃ for 10-30 minutes to stabilize the microporous structure and improve the mechanical properties of the membrane. Step (5): Surface treatment, plasma treatment or coating of functional coating on the film surface to improve its surface properties or give it antibacterial and oleophobic functions.

[0008] According to one embodiment of the present invention, the stretching temperature for the above-mentioned stretching to form a hole is 100-150°C, and the stretching ratio is 3-8 times.

[0009] According to one embodiment of the present invention, the sintering temperature is 300-380°C and the time is 10-30 minutes.

[0010] Compared with the prior art, the present invention can achieve the following technical effects: 1) This invention significantly improves the mechanical properties and micropore uniformity of PTFE membranes by introducing thermoplastic elastomers and nanofillers.

[0011] 2) The biaxial stretching and sintering process ensures the stability of the membrane's microporous structure and its air permeability.

[0012] 3) The product has excellent chemical corrosion resistance and high temperature resistance, making it suitable for harsh environments.

[0013] 4) The preparation process is simple and low-cost, making it suitable for large-scale production.

[0014] Of course, any product implementing this invention does not necessarily need to achieve all of the technical effects described above at the same time. Detailed Implementation

[0015] The following will describe the implementation of the present invention in detail with reference to the embodiments, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0016] A sintered PTFE composite microporous breathable membrane and its preparation method, comprising the following raw materials in parts by weight: 70-90 parts PTFE resin, 20-30 parts Ni-B-Si powder, 10-15 parts kerosene, 5-20 parts thermoplastic elastomer, 3-10 parts nanofiller, 0.2-0.6 parts initiator, 0.5-2 parts dispersant, and 0.1-0.5 parts antioxidant.

[0017] In detail, the thermoplastic elastomer is polyurethane, and the nanofiller is nano-silica.

[0018] Therefore, three sets of examples with different proportions were carried out according to the above method.

[0019] Example 1: Step (1): Raw material mixing. First, 70 parts by weight of thermoplastic elastomer, 3 parts by weight of nanofiller and 0.2 parts by weight of initiator are cross-linked. Then, the reactants are mixed with 0.5 parts by weight of dispersant and 0.1 parts by weight of antioxidant. The mixture is dispersed by a high-speed mixer or ball mill to obtain a uniform mixture. Step (2): Pre-forming. The mixture is pre-pressed into sheet or strip blanks by a calender or extruder. The surface of the sheet or strip blank is sandblasted. 20 parts by weight of Ni-B-Si and 10 parts by weight of kerosene are mixed evenly in proportion. Then, the mixture is... Spray on the surface of sheet or strip blanks and let stand for a period of time; Step (3): Stretch to form holes, stretch the blank in both longitudinal and transverse directions, stretch at 100-150℃, stretch ratio of 3-8 times, to form a microporous structure; Step (4): Sintering and shaping, sinter the stretched film at 300-380℃ for 10-30 minutes to stabilize the microporous structure and improve the mechanical properties of the film; Step (5): Surface treatment, plasma treatment or coating of functional coating on the film surface to improve its surface properties or give it antibacterial and oleophobic functions.

[0020] Example 2 Step (1): Raw material mixing, firstly, 80 parts by weight of thermoplastic elastomer, 7 parts by weight of nanofiller and 0.4 parts by weight of initiator are crosslinked, the reactants are mixed with 1.25 parts by weight of dispersant and 0.3 parts by weight of antioxidant, and dispersed by high-speed mixer or ball mill to obtain a uniform mixture; Step (2): Preforming, the mixture is pre-pressed into sheet or strip blanks by calender or extruder, and sandblasted on the surface of the sheet or strip blanks, and 25 parts by weight of Ni-B-Si and 12 are added. Mix 5 parts by weight of kerosene evenly according to the ratio, and then spray the mixture onto the surface of sheet or strip blanks and let it stand for a period of time; Step (3): Stretch to form holes, stretch the blank in both longitudinal and transverse directions, stretching temperature is 100-150℃, stretching ratio is 3-8 times, to form a microporous structure; Step (4): Sintering and shaping, sinter the stretched film at 300-380℃ for 10-30 minutes to stabilize the microporous structure and improve the mechanical properties of the film; Step (5): Surface treatment, perform plasma treatment or coat functional coating on the film surface to improve its surface properties or give it antibacterial and oleophobic functions.

[0021] Example 3: Step (1): Raw material mixing. First, 90 parts by weight of thermoplastic elastomer, 10 parts by weight of nanofiller and 0.6 parts by weight of initiator are crosslinked. Then, the reactants are mixed with 2 parts by weight of dispersant and 0.5 parts by weight of antioxidant. The mixture is dispersed by a high-speed mixer or ball mill to obtain a uniform mixture. Step (2): Preforming. The mixture is pre-pressed into sheet or strip blanks by a calender or extruder. The surface of the sheet or strip blank is sandblasted. 30 parts by weight of Ni-B-Si and 15 parts by weight of... The weight parts of kerosene are mixed evenly according to the ratio, and then the mixture is sprayed onto the surface of the sheet or strip blank and left to stand for a period of time; Step (3): Stretching to form holes, stretching the blank in both the longitudinal and transverse directions, stretching temperature is 100-150℃, stretching ratio is 3-8 times, forming a microporous structure; Step (4): Sintering and shaping, sintering the stretched film at 300-380℃ for 10-30 minutes to stabilize the microporous structure and improve the mechanical properties of the film; Step (5): Surface treatment, plasma treatment or coating of functional coating on the surface of the film to improve its surface properties or give it antibacterial and oleophobic functions.

[0022] In summary, the sintered PTFE composite microporous breathable membrane prepared in Example 1 has a breathability of 7000 g / m²·24h, a micropore size of 0.3 μm, a tensile strength of 20 MPa, and an elongation at break of 80%; the sintered PTFE composite microporous breathable membrane prepared in Example 2 has a breathability of 9000 g / m²·24h, a micropore size of 0.3 μm, a tensile strength of 32 MPa, and an elongation at break of 155%; the sintered PTFE composite microporous breathable membrane prepared in Example 3 has a breathability of 8000 g / m²·24h, a micropore size of 0.3 μm, a tensile strength of 29 MPa, and an elongation at break of 130%. Therefore, Example 2 exhibits the best overall performance.

[0023] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A sintered PTFE composite microporous breathable material, characterized in that, The raw materials include the following parts by weight: 70-90 parts PTFE resin, 20-30 parts Ni-B-Si, 10-15 parts kerosene, 5-20 parts thermoplastic elastomer, 3-10 parts nanofiller, 0.2-0.6 parts initiator, 0.5-2 parts dispersant, and 0.1-0.5 parts antioxidant.

2. The sintered PTFE composite microporous breathable membrane according to claim 1, characterized in that, The thermoplastic elastomer is polyurethane.

3. The sintered PTFE composite microporous breathable membrane according to claim 1, characterized in that, The nanofiller is nano-silica.

4. The method for preparing the sintered PTFE composite microporous breathable membrane according to claim 1, characterized in that, Step (1): Raw material mixing. First, cross-link the PTFE resin, thermoplastic elastomer, nanofiller and initiator. Then, mix the reactants with dispersant and antioxidant and disperse them through a high-speed mixer or ball mill to obtain a uniform mixture. Step (2): Pre-forming, the mixture is pre-pressed into sheet or strip blanks by calendering or extrusion, sandblasting the surface of the sheet or strip blanks, mixing Ni-B-Si and kerosene in a 2:1 ratio, and then spraying the mixture onto the surface of the sheet or strip blanks and letting it stand for a period of time. Step (3): Stretching to form holes, stretching the billet in both the longitudinal and transverse directions, stretching temperature is 100-150℃, stretching ratio is 3-8 times, forming a microporous structure; Step (4): Sintering and shaping. The stretched membrane is sintered at 300-380℃ for 10-30 minutes to stabilize the microporous structure and improve the mechanical properties of the membrane. Step (5): Surface treatment, plasma treatment or coating of functional coating on the film surface to improve its surface properties or give it antibacterial and oleophobic functions.

5. The method for preparing the sintered PTFE composite microporous breathable membrane according to claim 4, characterized in that, The stretching temperature for forming holes is 100-150℃, and the stretching ratio is 3-8 times.

6. The method for preparing the sintered PTFE composite microporous breathable membrane according to claim 4, characterized in that, The sintering temperature is 300-380℃, and the time is 10-30 minutes.