Manufacturing process of novel high-corrosion-resistance PI-PTFE (Polyimide-Polytetrafluoroethylene) composite microporous breathable material

Abstract

The invention discloses a manufacturing process of a novel high-corrosion-resistance PI-PTFE (Polyimide-Polytetrafluoroethylene) composite microporous breathable material. The manufacturing process comprises the following steps: mixing PI powder, Na2CO3 powder, SrCO3 powder and Mg (OH) 2 powder in a solvent; high-strength PI mixed powder is obtained after high-temperature sintering; the preparation method comprises the following steps: mixing PI mixed powder with a solvent to form slurry, coating a glass substrate with the slurry, and drying, pressing and heating to form PI films with different pore diameters or porosities; and finally, the composite film with high corrosion resistance is formed by gluing, hot melting welding or laser welding with the PTFE film. The PI powder, the Na2CO3 powder, the SrCO3 powder and the Mg (OH) 2 powder are sintered to prepare the PI film, and then the PTFE film is subjected to gluing, hot melting welding or laser welding to form the composite film, so that the low bonding property caused by blending is avoided, the high strength, high corrosion resistance and high air permeability in the use process are ensured, and the applicability is relatively high.

Description

Technical Field

[0001] The invention belongs to the technical field of PTFE membranes, and in particular relates to a manufacturing process of a novel highly corrosion-resistant PI-PTFE composite microporous breathable material. Background Art

[0002] Polyimide (PI) is a new type of high temperature resistant thermoplastic and solid engineering plastic. It can maintain high physical and mechanical properties in a wide temperature range of -270-400℃, and has excellent electrical insulation, wear resistance, high temperature radiation resistance and physical and mechanical properties; polytetrafluoroethylene (PTFE) has a wide frequency range and high and low temperature use range, excellent chemical stability, high electrical insulation, outstanding surface non-stickiness, good lubrication and atmospheric aging resistance. The two new materials are widely used in high-tech fields such as aviation, aerospace, electrical appliances, machinery, chemicals, microelectronics, instruments, petrochemicals, and measurement.

[0003] Therefore, from the viewpoint of composite material design, PTFE is compounded with PI, and the dimensional thermal stability of PI is utilized, and it is used as a continuous phase matrix, and PTFE is used as a filler to modify it, so that the water absorption rate can be reduced while reducing the dielectric constant, and a composite material with high thermal stability, low water absorption rate and low dielectric constant is obtained, so as to be suitable for the needs of dielectric substrates and electronic packaging. However, PI and PTFE belong to thermosetting and thermoplastic polymers, respectively, and their preparation process paths are completely different. In the past, PTFE / PI composite materials used as friction materials were prepared by mixing thermoplastic commercially available PI resin with PTFE suspension resin in a blender and then hot pressing. The combination of the two is poor, and the final formed film material is not high in strength, corrosion resistance or air permeability, so further improvement is needed. Summary of the invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a new manufacturing process of a highly corrosion-resistant PI-PTFE composite microporous breathable material, which is used to avoid the problem of poor corrosion resistance and air permeability of previous PI-PTFE composite membranes.

[0005] In order to solve the above technical problems, the present invention discloses a novel manufacturing process of a highly corrosion-resistant PI-PTFE composite microporous breathable material, comprising: Step a. Mix PI powder, Na2CO3 powder, SrCO3 powder and Mg(OH)2 powder in a solvent; Step b. placing the mixed powder in a hot press for pressing to obtain a green body, and heating and drying the green body in a vacuum reactor to remove moisture; Step c. placing the molded part in a high-temperature kiln for sintering, and obtaining a high-strength PI mixed powder after cooling; Step d. mixing the PI mixed powder with a solvent to form a slurry, coating the slurry on a glass substrate, and drying, pressing, and heating to form a PI film with different pore sizes or porosities; Step e. Weighing 20% ​​wt of kerosene and polytetrafluoroethylene fine powder, preparing a PTFE membrane with a pore size of 0.1µm-0.2µm and a porosity of ≥85% by blending, compacting, extrusion, calendering, degreasing, uniaxial stretching, biaxial stretching and curing steps; Step f. The PTFE membrane is bonded, hot-melt welded or laser welded to the surface of the PI membrane to form a highly corrosion-resistant composite membrane.

[0006] According to one embodiment of the present invention, the weight proportion of the PI powder is 80-100 parts, the weight proportion of the Na2CO3 powder is 8-12 parts, the weight proportion of the SrCO3 powder is 4-6 parts, and the weight proportion of the Mg(OH)2 powder is 3-5 parts.

[0007] According to one embodiment of the present invention, the solvent is selected from one of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), phenol / formaldehyde solution, chloroform and acetone.

[0008] According to one embodiment of the present invention, the temperature in the above step c is first slowly increased to 280°C, kept warm for 2 hours, then increased to 310°C, kept warm for 2 hours, then increased to 320°C, kept warm for 4-8 hours, and finally cooled with the furnace.

[0009] According to one embodiment of the present invention, the thickness of the PI film is greater than the thickness of the PTFE film.

[0010] Compared with the prior art, the present invention can achieve the following technical effects: The PI membrane is prepared by sintering PI powder, Na2CO3 powder, SrCO3 powder, and Mg(OH)2 powder, and then the PTFE membrane is glued, hot-melt welded or laser welded to form a composite membrane. This avoids the low bonding caused by blending, ensures high strength, high corrosion resistance, and high air permeability during use, and has strong applicability.

[0011] Of course, any product implementing the present invention does not necessarily need to achieve all of the above-mentioned technical effects at the same time. DETAILED DESCRIPTION

[0012] The following embodiments are used to explain the implementation methods of the present invention in detail, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0013] The present invention discloses a novel manufacturing process of a highly corrosion-resistant PI-PTFE composite microporous breathable material, comprising: Step a. Place PI powder, Na2CO3 powder, SrCO3 powder and Mg(OH)2 powder in a solvent for mixing; wherein Na2CO3 powder, SrCO3 powder and Mg(OH)2 powder can improve strength and promote blending.

[0014] Step b. placing the mixed powder in a hot press for pressing to obtain a green body, and heating and drying the green body in a vacuum reactor to remove moisture; Step c. placing the molded part in a high-temperature kiln for sintering, and obtaining a high-strength PI mixed powder after cooling; Step d. mixing the PI mixed powder with a solvent to form a slurry, coating the slurry on a glass substrate, and drying, pressing, and heating to form a PI film with different pore sizes or porosities; Step e. Weighing 20% ​​wt of kerosene and polytetrafluoroethylene fine powder, preparing a PTFE membrane with a pore size of 0.1µm-0.2µm and a porosity of ≥85% by blending, compacting, extrusion, calendering, degreasing, uniaxial stretching, biaxial stretching and curing steps; Step f. The PTFE membrane is bonded, hot-melt welded or laser welded to the surface of the PI membrane to form a highly corrosion-resistant composite membrane.

[0015] Preferably, the weight proportion of PI powder is 80-100 parts, the weight proportion of Na2CO3 powder is 8-12 parts, the weight proportion of SrCO3 powder is 4-6 parts, and the weight proportion of Mg(OH)2 powder is 3-5 parts.

[0016] The solvent is selected from one of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), phenol / formaldehyde solution, chloroform and acetone. Example 1

[0017] Step a. Mix PI powder, Na2CO3 powder, SrCO3 powder and Mg(OH)2 powder in a solvent, wherein the PI powder is 80 parts by weight, the Na2CO3 powder is 8 parts by weight, the SrCO3 powder is 4 parts by weight and the Mg(OH)2 powder is 3 parts by weight; Step b. placing the mixed powder in a hot press for pressing to obtain a green body, and heating and drying the green body in a vacuum reactor to remove moisture; Step c. placing the molded part in a high-temperature kiln for sintering, and obtaining a high-strength PI mixed powder after cooling; Step d. mixing the PI mixed powder with a solvent to form a slurry, coating the slurry on a glass substrate, and drying, pressing, and heating to form a PI film with different pore sizes or porosities; Step e. Weighing 20% ​​wt of kerosene and polytetrafluoroethylene fine powder, preparing a PTFE membrane with a pore size of 0.1µm-0.2µm and a porosity of ≥85% by blending, compacting, extrusion, calendering, degreasing, uniaxial stretching, biaxial stretching and curing steps; Step f. The PTFE membrane is bonded, hot-melt welded or laser welded to the surface of the PI membrane to form a highly corrosion-resistant composite membrane. Example 2

[0018] Step a. Mix PI powder, Na2CO3 powder, SrCO3 powder and Mg(OH)2 powder in a solvent, wherein the PI powder is 100 parts by weight, the Na2CO3 powder is 12 parts by weight, the SrCO3 powder is 6 parts by weight and the Mg(OH)2 powder is 5 parts by weight; Step b. placing the mixed powder in a hot press for pressing to obtain a green body, and heating and drying the green body in a vacuum reactor to remove moisture; Step c. placing the molded part in a high-temperature kiln for sintering, and obtaining a high-strength PI mixed powder after cooling; Step d. mixing the PI mixed powder with a solvent to form a slurry, coating the slurry on a glass substrate, and drying, pressing, and heating to form a PI film with different pore sizes or porosities; Step e. Weighing 20% ​​wt of kerosene and polytetrafluoroethylene fine powder, preparing a PTFE membrane with a pore size of 0.1µm-0.2µm and a porosity of ≥85% by blending, compacting, extrusion, calendering, degreasing, uniaxial stretching, biaxial stretching and curing steps; Step f. The PTFE membrane is bonded, hot-melt welded or laser welded to the surface of the PI membrane to form a highly corrosion-resistant composite membrane. Example 3

[0019] Step a. Mix PI powder, Na2CO3 powder, SrCO3 powder and Mg(OH)2 powder in a solvent, wherein the PI powder is 90 parts by weight, the Na2CO3 powder is 10 parts by weight, the SrCO3 powder is 5 parts by weight and the Mg(OH)2 powder is 4 parts by weight; Step b. placing the mixed powder in a hot press for pressing to obtain a green body, and heating and drying the green body in a vacuum reactor to remove moisture; Step c. placing the molded part in a high-temperature kiln for sintering, and obtaining a high-strength PI mixed powder after cooling; Step d. mixing the PI mixed powder with a solvent to form a slurry, coating the slurry on a glass substrate, and drying, pressing, and heating to form a PI film with different pore sizes or porosities; Step e. Weighing 20% ​​wt of kerosene and polytetrafluoroethylene fine powder, preparing a PTFE membrane with a pore size of 0.1µm-0.2µm and a porosity of ≥85% by blending, compacting, extrusion, calendering, degreasing, uniaxial stretching, biaxial stretching and curing steps; Step f. The PTFE membrane is bonded, hot-melt welded or laser welded to the surface of the PI membrane to form a highly corrosion-resistant composite membrane. Example 4

[0020] Step a. mixing PI powder in a solvent, wherein the weight of PI powder is 90 parts; Step b. placing the mixed powder in a hot press for pressing to obtain a green body, and heating and drying the green body in a vacuum reactor to remove moisture; Step c. placing the molded part in a high-temperature kiln for sintering, and obtaining a high-strength PI mixed powder after cooling; Step d. mixing the PI mixed powder with a solvent to form a slurry, coating the slurry on a glass substrate, and drying, pressing, and heating to form a PI film with different pore sizes or porosities; Step e. Weighing 20% ​​wt of kerosene and polytetrafluoroethylene fine powder, preparing a PTFE membrane with a pore size of 0.1µm-0.2µm and a porosity of ≥85% by blending, compacting, extrusion, calendering, degreasing, uniaxial stretching, biaxial stretching and curing steps; Step f. The PTFE membrane is bonded, hot-melt welded or laser welded to the surface of the PI membrane to form a highly corrosion-resistant composite membrane.

[0021] The properties of the composites prepared in the above-mentioned embodiment are shown in the following table: Project Name Tensile strength / N Filter turbidity / NTU Pure water flux / LMH Implementation Case 1 73 0.163 2003 Implementation Case 2 75 0.173 2052 Implementation Case 3 91 0.246 2267 Implementation Case 4 65 0.152 1903 Moreover, after the salt spray test, it was found that the composite film in Example 3 had the strongest corrosion resistance. It can be seen that the composite film in Example 3 has the highest strength, the strongest corrosion resistance, and the best waterproof and breathable properties.

[0022] Preferably, the temperature in the above step c is first slowly increased to 280°C, kept warm for 2 hours, then increased to 310°C, kept warm for 2 hours, then increased to 320°C, kept warm for 4-8 hours, and finally cooled with the furnace.

[0023] In addition, the thickness of the PI film is greater than that of the PTFE film, which ensures the strength of the composite film.

[0024] In summary, the present invention prepares a PI membrane by sintering PI powder, Na2CO3 powder, SrCO3 powder, and Mg(OH)2 powder, and then glues, hot-melt welds, or laser welds a PTFE membrane to form a composite membrane, thereby avoiding low bonding caused by blending, ensuring high strength, high corrosion resistance, and high air permeability during use, and having strong applicability.

[0025] The above description shows and describes several preferred embodiments of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept described herein through the above teachings or the technology or knowledge of the relevant field. Changes and variations made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A new type of highly corrosion-resistant PI-PTFE composite microporous breathable material manufacturing process, characterized in that: include: Step a. Mix PI powder, Na2CO3 powder, SrCO3 powder and Mg(OH)2 powder in a solvent; Step b. placing the mixed powder in a hot press for pressing to obtain a green body, and heating and drying the green body in a vacuum reactor to remove moisture; Step c. placing the molded part in a high-temperature kiln for sintering, and obtaining a high-strength PI mixed powder after cooling; Step d. mixing the PI mixed powder with a solvent to form a slurry, coating the slurry on a glass substrate, and drying, pressing, and heating to form a PI film with different pore sizes or porosities; Step e. Weighing 20% ​​wt of kerosene and polytetrafluoroethylene fine powder, preparing a PTFE membrane with a pore size of 0.1µm-0.2µm and a porosity of ≥85% by blending, compacting, extrusion, calendering, degreasing, uniaxial stretching, biaxial stretching and curing steps; Step f. The PTFE membrane is bonded, hot-melt welded or laser welded to the surface of the PI membrane to form a highly corrosion-resistant composite membrane.

2. The manufacturing process of the novel highly corrosion-resistant PI-PTFE composite microporous breathable material according to claim 1 is characterized in that: The weight proportion of the PI powder is 80-100 parts, the weight proportion of the Na2CO3 powder is 8-12 parts, the weight proportion of the SrCO3 powder is 4-6 parts, and the weight proportion of the Mg(OH)2 powder is 3-5 parts.

3. The manufacturing process of the novel highly corrosion-resistant PI-PTFE composite microporous breathable material according to claim 1 is characterized in that: The solvent is selected from one of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), phenol / formaldehyde solution, chloroform and acetone.

4. The manufacturing process of the novel highly corrosion-resistant PI-PTFE composite microporous breathable material according to claim 1 is characterized in that: In the step c, the temperature is first slowly raised to 280° C., kept warm for 2 hours, then raised to 310° C., kept warm for 2 hours, then raised to 320° C., kept warm for 4-8 hours, and finally cooled with the furnace.

5. The manufacturing process of the novel highly corrosion-resistant PI-PTFE composite microporous breathable material according to claim 1 is characterized in that: The thickness of the PI film is greater than the thickness of the PTFE film.