CN113088018B - Polytetrafluoroethylene breathable film and preparation method and application thereof - Google Patents
Polytetrafluoroethylene breathable film and preparation method and application thereof Download PDFInfo
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- CN113088018B CN113088018B CN202110399951.0A CN202110399951A CN113088018B CN 113088018 B CN113088018 B CN 113088018B CN 202110399951 A CN202110399951 A CN 202110399951A CN 113088018 B CN113088018 B CN 113088018B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/24—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by surface fusion and bonding of particles to form voids, e.g. sintering
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/0061—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof characterized by the use of several polymeric components
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
- C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
- C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C08J2327/18—Homopolymers or copolymers of tetrafluoroethylene
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2427/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
- C08J2427/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
- C08J2427/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C08J2427/18—Homopolymers or copolymers of tetrafluoroethylene
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention provides a polytetrafluoroethylene breathable film which comprises the following raw materials in parts by weight: 20-100 parts of polytetrafluoroethylene sintering material and 10-40 parts of second polytetrafluoroethylene resin; the preparation raw materials of the polytetrafluoroethylene sintering material comprise a composition of a first polytetrafluoroethylene resin and a filler, and D of the polytetrafluoroethylene sintering material 50 The grain diameter is 50-150 mu m. The polytetrafluoroethylene breathable film is prepared by mixing a polytetrafluoroethylene sintering material with a specific particle size and PTFE resin and then carrying out die pressing, sintering and turning processes, pore-forming agents and solvents are not needed, the process is simple, the operation is easy, and the environmental friendliness is good; the polytetrafluoroethylene breathable film has a porous structure with uniform distribution and controllable size and porosity in a microscopic view, has excellent air permeability, water resistance and mechanical strength, and fully meets the application requirements of the polytetrafluoroethylene breathable film in an explosion-proof valve.
Description
Technical Field
The invention belongs to the technical field of polymer materials, and particularly relates to a polytetrafluoroethylene breathable film as well as a preparation method and application thereof.
Background
The explosion-proof valve is one of important explosion-proof devices of the power battery, has the main functions of maintaining the balance of air pressure inside and outside the battery pack, preventing liquid oil stain and dust from entering a battery pack shell, and releasing pressure in time when the battery is out of control due to heat, and the safety performance of the power battery is obviously improved due to the arrangement of the explosion-proof valve. The explosion-proof valve generally comprises a body, a pressure relief opening, a puncture structure, an explosion-proof valve film and other structures, wherein the explosion-proof valve film is a core component of the whole product and has the functions of quickly ventilating, balancing internal and external pressure differences, blocking dust and oil stains and participating in explosion-proof pressure relief. In addition to the above functions, the thin film of the explosion-proof valve needs to have the properties of chemical reagent resistance, high and low temperature resistance, ultraviolet ray resistance and the like so as to further improve the use reliability of the explosion-proof valve in a harsh environment.
The explosion-proof valve film can be roughly classified into a gas-permeable type explosion-proof film and a non-gas-permeable type explosion-proof film, the gas-permeable type explosion-proof film is mostly a Polytetrafluoroethylene (PTFE) microporous film, and the non-gas-permeable type explosion-proof film includes a PE film, a PET film, a PP film, and the like. In the current mainstream explosion-proof valve products, the PTFE microporous film with better air permeability is applied more widely, so the development and performance optimization of the PTFE microporous film are important components in the research of the explosion-proof valve.
CN111864152A discloses a breathable explosion-proof membrane for an explosion-proof valve of a power battery, wherein the explosion-proof membrane is a porous waterproof breathable polytetrafluoroethylene membrane, and is prepared by uniformly mixing polytetrafluoroethylene suspension resin and a pore-forming agent, performing mould pressing to form a blank, sintering, cooling, turning and rolling. The structure of the explosion-proof membrane obtained by the method is that the surfaces of micron-sized polytetrafluoroethylene suspension resin microspheres are fused and mutually connected and stacked to form a microporous membrane with a plurality of air permeable pore canals, and the air permeability is adjusted by controlling the aperture size and the porosity of the explosion-proof membrane, so that the purpose of balancing the internal pressure and the external pressure of the battery pack is achieved. The explosion-proof membrane has a porous structure with the aperture range of 0.3-20 mu m, but the porous structure is formed by thermal decomposition of a pore-foaming agent, the uniformity of pore position distribution is poor, the mechanical strength of the membrane is poor, and the use stability is influenced.
CN106832695A discloses a PTFE film for an explosion-proof valve and a preparation method thereof, wherein the PTFE film comprises the following components in parts by weight: 50-65 parts of PTFE resin, 5-20 parts of calcium oxide, 2-10 parts of dry ice, 5-15 parts of polyurethane and 10-20 parts of polyphenyl ester; the preparation method of the PTFE film comprises the following steps: the method comprises the following steps of raw material pretreatment, weighing and material preparation, stirring and mixing, drying treatment, melting treatment, cooling treatment, cutting treatment and film forming treatment. The PTFE film for the explosion-proof valve has good stability, but also has a large promotion space in the aspects of air permeability, water pressure resistance and mechanical strength.
US5417743 discloses a porous PTFE film which is prepared by taking PTFE dispersed resin and fibers as raw materials through a stretching process, has a microstructure of fiber/node, and has a gas permeation function through pores among the fibers in the film. However, the porous membrane has a complex preparation process, the pore size, pore size distribution, pore size and porosity of the PTFE membrane are difficult to control, and the dimensional stability is poor.
Therefore, it is an urgent problem in the art to develop a thin film material having excellent air permeability, mechanical properties and water resistance to meet the application requirements of the explosion-proof valve for a battery.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a polytetrafluoroethylene breathable film and a preparation method and application thereof, wherein the polytetrafluoroethylene breathable film is prepared from a polytetrafluoroethylene sintering material containing fillers and Polytetrafluoroethylene (PTFE) resin, and the polytetrafluoroethylene sintering material with a specific particle size and the PTFE resin are cooperated with each other, so that the polytetrafluoroethylene breathable film is endowed with a pore size structure with uniform distribution and controllable size and porosity, has excellent air permeability, has outstanding water resistance and proper mechanical strength, and fully meets the application requirements of the polytetrafluoroethylene breathable film in an explosion-proof valve.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a polytetrafluoroethylene breathable film, which comprises the following raw materials in parts by weight: 20-100 parts of polytetrafluoroethylene sintering material and 10-40 parts of second polytetrafluoroethylene resin; the raw materials for preparing the polytetrafluoroethylene sintered material comprise a composition of a first polytetrafluoroethylene resin and a filler, and D of the polytetrafluoroethylene sintered material 50 The particle diameter (median diameter) is 50 to 150 μm.
The raw materials for preparing the polytetrafluoroethylene breathable film comprise a polytetrafluoroethylene sintering material and second polytetrafluoroethylene resin; the polytetrafluoroethylene sintering material with the specific particle size has a hard particle structure, the second polytetrafluoroethylene resin particles are soft in texture and easy to compress, and the two particles are mutually cooperated, so that the raw materials are more easily and fully contacted and fused in the die pressing and sintering processes, a large gap structure among the particles is eliminated, a film with a porous structure which is uniform in distribution on the microcosmic and controllable in pore size and porosity is formed, and the polytetrafluoroethylene breathable film is endowed with excellent air permeability and mechanical properties. Meanwhile, the polytetrafluoroethylene sintered material is formed by pre-sintering the first polytetrafluoroethylene resin and the filler, the filler is uniformly dispersed in the polymer matrix and is cooperated with the PTFE polymer, and the mechanical strength, the water resistance, the air permeability and other functionalities of the polytetrafluoroethylene breathable film are further improved.
According to the invention, through the design and synergistic compounding of the polytetrafluoroethylene sintering material and the polytetrafluoroethylene resin, the polytetrafluoroethylene breathable film has excellent air permeability, water resistance and mechanical strength, is low in thermal shrinkage rate and good in dimensional stability, and is particularly suitable for an explosion-proof film of an explosion-proof valve of a battery pack. The polytetrafluoroethylene breathable film does not need to additionally use a pore-forming agent, the pore diameter structure of the film is uniformly distributed, the porosity and the pore diameter range are controllable, and the preparation method is simple and environment-friendly and has wide industrial application prospect.
In the present invention, the amount of the polytetrafluoroethylene sintering material is 20 to 100 parts, for example, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts or 95 parts, and specific values therebetween are not exhaustive, and for brevity, the specific values included in the range are not exhaustive.
The second polytetrafluoroethylene resin is 10-40 parts, for example, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, 32 parts, 35 parts or 38 parts, and the specific values therebetween are not exhaustive, and for brevity and clarity, the invention is not intended to be limited to the specific values included in the ranges.
D of the polytetrafluoroethylene sintering material 50 The particle size may be, for example, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, or,95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm or 145 μm, and specific values therebetween, are not intended to be exhaustive of the invention and for the sake of brevity, the invention is not intended to be limited to the specific values encompassed by the scope disclosed.
In the present invention, D is the amount of the polytetrafluoroethylene sintering material 50 The grain diameter is 50-150 μm, which can make the polytetrafluoroethylene ventilated membrane obtain good balance among air permeability, water resistance and mechanical property. If the particle size of the polytetrafluoroethylene sintering material is too small, the microscopic pore diameter of the polytetrafluoroethylene breathable film is small, the porosity is low, and the air permeability is poor; if the particle size of the polytetrafluoroethylene sintering material is too large, the porosity of the breathable film is increased, the pore size is large, the air permeability is improved, but the water resistance and the mechanical strength are reduced.
Preferably, in the raw material for preparing the polytetrafluoroethylene sintered material, the mass ratio of the first polytetrafluoroethylene resin to the filler is 1 (0.01-0.8), and may be, for example, 1.
Preferably, the filler is an organic filler.
Preferably, the organic filler is a meltable fluoropolymer filler.
Preferably, the meltable fluoropolymer filler is selected from any one or a combination of at least two of polyvinylidene fluoride (PVDF) filler, fluorinated ethylene propylene copolymer (FEP) filler, or soluble Polytetrafluoroethylene (PFA) filler.
As a preferred technical scheme of the invention, the filler is a meltable fluorine-containing polymer filler, which is not only beneficial to improving the mechanical strength and the air permeability of the polytetrafluoroethylene breathable film, but also can obviously improve the microporous structure and the water resistance of the film, and further optimization of the comprehensive performance of the polytetrafluoroethylene breathable film is realized.
Preferably, the powder density of the first polytetrafluoroethylene resin is 350-450 g/L, for example, 355g/L, 360g/L, 365g/L, 370g/L, 375g/L, 380g/L, 385g/L, 390g/L, 395g/L, 400g/L, 405g/L, 410g/L, 415g/L, 420g/L, 425g/L, 430g/L, 435g/L, 440g/L or 445g/L, and the specific values therebetween are limited to space and for the sake of brevity, and the invention does not exhaust the specific values included in the range.
Preferably, the first melting point of the first polytetrafluoroethylene resin is 340 to 350 ℃ (e.g., 341 ℃, 342 ℃, 343 ℃, 344 ℃, 345 ℃, 346 ℃, 347 ℃, 348 ℃, 349 ℃ or the like), and the second melting point is 320 to 330 ℃ (e.g., 321 ℃, 322 ℃, 323 ℃, 324 ℃, 325 ℃, 326 ℃, 327 ℃, 328 ℃, 329 ℃ or the like).
In the present invention, the first melting point of the polytetrafluoroethylene resin means the position of the melting peak on the DSC (differential scanning calorimetry) primary temperature rise curve; the second melting point means the position of the melting peak on the DSC second temperature rise curve. The same description is referred to below, all having the same meaning.
The first melting point of the first polytetrafluoroethylene resin is 340-350 ℃, and the second melting point is 320-330 ℃; namely, only one melting peak at 340-350 ℃ is positioned on the DSC first temperature rising curve of the first polytetrafluoroethylene resin, and only one melting peak at 320-330 ℃ is positioned on the second temperature rising curve.
Preferably, the polytetrafluoroethylene sintering material is a polytetrafluoroethylene complete sintering material and/or a polytetrafluoroethylene semi-sintering material.
The DSC (differential scanning calorimetry) one-time heating curve of the polytetrafluoroethylene fully-sintered material has only one melting peak and is positioned at 320-330 ℃; the DSC primary heating curve of the polytetrafluoroethylene semi-sintered material has two melting peaks which are respectively positioned at 320-330 ℃ and 340-350 ℃.
Preferably, the polytetrafluoroethylene sintering material is prepared by adopting a method comprising the following steps: and uniformly mixing the first polytetrafluoroethylene resin and the filler, sintering, and crushing a sintered product to obtain the polytetrafluoroethylene sintered material.
Preferably, the sintering temperature is 340-380 ℃, for example 342 ℃, 345 ℃, 348 ℃, 350 ℃, 352 ℃, 355 ℃, 358 ℃,360 ℃, 362 ℃, 365 ℃, 368 ℃,370 ℃, 372 ℃, 375 ℃ or 378 ℃, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive of the specific values included in the range.
Preferably, the sintering time is 2 to 10 hours, for example, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, 9 hours or 9.5 hours, and specific values therebetween are not limited by space and for the sake of brevity, and the invention is not exhaustive list of specific values included in the range.
Preferably, the polytetrafluoroethylene sintering material is a polytetrafluoroethylene complete sintering material, the sintering temperature is 360-380 ℃ and does not include 360 ℃, and the time is 5-10 h.
Preferably, the polytetrafluoroethylene sintering material is a polytetrafluoroethylene semi-sintering material, the sintering temperature is 340-360 ℃, and the time is 2-4 h.
Preferably, the method of comminution comprises any one or a group of at least two of dry milling, water milling or gas milling.
Preferably, the step of sieving is further included after the crushing.
Preferably, D of the polytetrafluoroethylene frit 50 The grain diameter is 60-100 μm.
Preferably, D of the polytetrafluoroethylene frit 10 The particle size is 10 to 50 μm, and may be, for example, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, 28 μm, 30 μm, 32 μm, 35 μm, 38 μm, 40 μm, 42 μm, 45 μm or 48 μm, and more preferably 20 to 30 μm.
Preferably, D of the polytetrafluoroethylene frit 90 The particle diameter is 150 to 300. Mu.m, and may be, for example, 160. Mu.m, 180. Mu.m, 200. Mu.m, 210. Mu.m, 220. Mu.m, 230. Mu.m, 240. Mu.m, 250. Mu.m, 260. Mu.m, 270. Mu.m, 280. Mu.m, 290. Mu.m, etc., and more preferably 200 to 250. Mu.m.
As a preferred embodiment of the present invention, the poly (tetra) isD of vinyl fluoride sintering material 10 Particle size of 10-50 μm, D 90 Particle size of 150-300 μm, D 50 The particle diameter is 50 to 150. Mu.m, and more preferably 60 to 100. Mu.m. The particle size and the particle size distribution of the polytetrafluoroethylene sintering material can directly influence the air permeability and the water resistance of the polytetrafluoroethylene breathable film, the more the large-particle-size part is, the better the air permeability is, the lower the bubble point pressure is, and the lower the water pressure resistance is; the larger the small particle size, the poorer the air permeability, the higher the bubble point pressure, and the higher the water pressure resistance.
All particle size data involved in the invention are obtained by dry testing with a laser particle sizer.
Preferably, the powder density of the second polytetrafluoroethylene resin is 350-450 g/L, for example, 355g/L, 360g/L, 365g/L, 370g/L, 375g/L, 380g/L, 385g/L, 390g/L, 395g/L, 400g/L, 405g/L, 410g/L, 415g/L, 420g/L, 425g/L, 430g/L, 435g/L, 440g/L or 445g/L, and the specific values therebetween are limited to space and the specific values included in the range are not exhaustive for the sake of brevity.
Preferably, D of said second polytetrafluoroethylene resin 50 The particle size is 10-100 μm, and may be, for example, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm or 95 μm, and specific values therebetween, not to be limiting in space and for the sake of brevity, the invention is not intended to be exhaustive of the specific values encompassed by the scope.
Preferably, the second polytetrafluoroethylene resin has a first melting point of 340 to 350 ℃ (e.g., 341 ℃, 342 ℃, 343 ℃, 344 ℃, 345 ℃, 346 ℃, 347 ℃, 348 ℃, 349 ℃ or the like), and a second melting point of 320 to 330 ℃ (e.g., 321 ℃, 322 ℃, 323 ℃, 324 ℃, 325 ℃, 326 ℃, 327 ℃, 328 ℃, 329 ℃ or the like).
The first melting point of the second polytetrafluoroethylene resin is 340-350 ℃, and the second melting point is 320-330 ℃; namely, only one melting peak at 340-350 ℃ is positioned on the DSC first temperature rising curve of the second polytetrafluoroethylene resin, and only one melting peak at 320-330 ℃ is positioned on the second temperature rising curve.
Preferably, the mass ratio of the polytetrafluoroethylene sintered material to the second polytetrafluoroethylene resin is 1 (0.2 to 2.5), and may be, for example, 1.
In a preferred embodiment of the present invention, the sintered polytetrafluoroethylene material and the second polytetrafluoroethylene resin are cooperated with each other at the above-mentioned mass ratio, so that the polytetrafluoroethylene gas-permeable membrane can have a better balance among air permeability, water resistance and mechanical strength. If the amount of the polytetrafluoroethylene sintering material is too much, particles are not easy to fuse, so that the film has more pores and good air permeability, but has lower mechanical strength and poor water pressure resistance; if the amount of the second polytetrafluoroethylene resin is too large, the film has high mechanical strength, but the breathability is difficult to meet the application requirements.
Preferably, the mass of the filler is 5-20% based on 100% of the total mass of the polytetrafluoroethylene sintered material and the second polytetrafluoroethylene resin, for example, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18% or 19%, and specific values therebetween are not exhaustive, and for brevity and clarity, the invention is not exhaustive.
Preferably, the polytetrafluoroethylene breathable film has a thickness of 0.1 to 0.5mm, and may be, for example, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, 0.32mm, 0.35mm, 0.38mm, 0.4mm, 0.42mm, 0.45mm or 0.48mm, and specific values therebetween are not intended to be limited to space and for the sake of brevity, and the invention is not intended to be exhaustive of the specific values included in the range.
Preferably, the polytetrafluoroethylene gas permeable membrane is a porous membrane having a pore size of 0.5 to 6 μm, and may be, for example, 0.6 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, 5 μm, 5.2 μm, 5.5 μm, or 5.8 μm, and specific values therebetween are limited to space and for the sake of brevity, and the present invention is not exhaustive.
In a second aspect, the present invention provides a method for producing a polytetrafluoroethylene breathable film according to the first aspect, the method comprising: and uniformly mixing the polytetrafluoroethylene sintered material with a second polytetrafluoroethylene resin, and then sequentially carrying out die pressing, sintering and turning to obtain the polytetrafluoroethylene breathable film.
The polytetrafluoroethylene breathable film provided by the invention is prepared by uniformly mixing the raw materials and then carrying out processes of die pressing, sintering and turning, and the preparation method does not need to additionally add a pore-forming agent or use an organic solvent, is simple in process, easy to operate, free of a large amount of industrial three wastes, good in environmental friendliness and suitable for large-scale industrial production.
Preferably, the pressure of the molding is 8 to 30MPa, for example, 9MPa, 10MPa, 11MPa, 13MPa, 15MPa, 17MPa, 19MPa, 20MPa, 22MPa, 24MPa, 26MPa or 28MPa, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive and does not list the specific values included in the range, and more preferably 10 to 20MPa.
Preferably, the time for the molding is 5-50 min, for example, 8min, 10min, 12min, 15min, 18min, 20min, 22min, 25min, 28min, 30min, 32min, 35min, 38min, 40min, 42min, 45min or 48min, and the specific point values between the above point values are limited to space and for simplicity, the invention does not exhaust the specific point values included in the range, and more preferably 10-30 min.
Preferably, the sintering temperature is 300 to 400 ℃, and for example, may be 305 ℃, 310 ℃, 315 ℃, 320 ℃, 325 ℃, 330 ℃, 335 ℃,340 ℃, 345 ℃, 350 ℃, 355 ℃,360 ℃, 365 ℃,370 ℃, 375 ℃,380 ℃, 385 ℃, 390 ℃ or 395 ℃, and specific values therebetween, are limited to space and for the sake of brevity, and the present invention is not exhaustive enumeration of specific values included in the range.
Preferably, the sintering time is 8 to 20 hours, for example, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours, 12.5 hours, 13 hours, 13.5 hours, 14 hours, 14.5 hours, 15 hours, 15.5 hours, 16 hours, 16.5 hours, 17 hours, 17.5 hours, 18 hours, 18.5 hours, 19 hours or 19.5 hours, and the specific point values between the above point values are limited by space and for the sake of brevity, the invention is not exhaustive and the specific point values included in the range are not included in the invention.
Preferably, the specific method of sintering comprises: firstly, heating the reaction system to 300-335 ℃ (for example 305 ℃, 310 ℃, 315 ℃, 320 ℃, 325 ℃ or 330 ℃ and the like), and preserving heat for 2-4 h (for example 2.2h, 2.5h, 2.8h, 3h, 3.2h, 3.5h or 3.8h and the like); then heating to 350-400 deg.C (such as 355 deg.C, 360 deg.C, 365 deg.C, 370 deg.C, 375 deg.C, 380 deg.C, 385 deg.C, 390 deg.C or 395 deg.C), and keeping the temperature for 4-6 h (such as 4.2h, 4.5h, 4.8h, 5h, 5.2h, 5.5h or 5.8 h); cooling to 300-335 deg.C (such as 305 deg.C, 310 deg.C, 315 deg.C, 320 deg.C, 325 deg.C or 330 deg.C), and maintaining for 2-4 h (such as 2.2h, 2.5h, 2.8h, 3h, 3.2h, 3.5h or 3.8 h); and finally, cooling to room temperature to obtain a sintered product.
In a third aspect, the present invention provides a use of the polytetrafluoroethylene gas-permeable membrane according to the first aspect in a waterproof component, a gas-permeable component, a packaging material or a battery material.
Compared with the prior art, the invention has the following beneficial effects:
(1) The raw materials for preparing the polytetrafluoroethylene breathable film comprise a polytetrafluoroethylene sintering material containing a filler and a second polytetrafluoroethylene resin, and the polytetrafluoroethylene sintering material with a specific particle size and the PTFE resin are mutually cooperated, so that the polytetrafluoroethylene breathable film has a porous structure with uniform distribution and controllable size and porosity in a microscopic view, and has excellent air permeability, water resistance and mechanical strength.
(2) The polytetrafluoroethylene breathable film is prepared through the processes of die pressing, sintering and turning, no pore-forming agent is required to be additionally added, and the process is simple and easy to operate; and no organic solvent is needed, so that a large amount of industrial three wastes are not generated, the environmental protection property is good, and the method is suitable for large-scale industrial production.
(3) The invention ensures that the average pore diameter of the polytetrafluoroethylene breathable film is 0.8-3 mu m and the gas flux reaches 210-900 mL/min/cm through the design of the particle diameter of the polytetrafluoroethylene sintering material and the filler and the optimization of the proportion of the polytetrafluoroethylene sintering material and the PTFE resin 2 @7kPa, density of 1.0-1.7 g/cm 3 The water pressure resistance is more than or equal to 35kPa, can reach more than 50kPa, the thermal shrinkage rate is less than or equal to 2.0 percent, the tensile strength reaches 12.5-24 MPa, good balance among air permeability, water resistance and mechanical strength is obtained, the shrinkage rate is low, the scale temperature property is good, and the application requirement of the polytetrafluoroethylene breathable film in the battery pack explosion-proof valve can be fully met.
Detailed Description
The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Preparation example 1
A polytetrafluoroethylene sintering material, in particular to a polytetrafluoroethylene complete sintering material; the preparation raw materials comprise the following components in parts by weight: 80 parts of PTFE resin (Dajin M18, powder density of 400g/L, first melting point of 340.3 ℃, second melting point of 327.5 ℃) and 20 parts of soluble polytetrafluoroethylene filler (PFA filler, kodao chemical Teflon 345). The preparation method comprises the following steps:
uniformly mixing PTFE resin and PFA filler, sintering at 380 ℃ for 6 hours, crushing a sintered product by a dry grinding method, and screening to obtain a polytetrafluoroethylene completely sintered material; dry test with a laser particle sizer, D 10 Particle size 30 μm, D 90 Particle size 220 μm, D 50 The particle size was 70 μm.
Preparation example 2
A polytetrafluoroethylene sintering material, in particular to a polytetrafluoroethylene semi-sintering material; the preparation raw materials comprise the following components in parts by weight: 80 parts of PTFE resin (Dajin M18), 20 parts of PFA filler (Teflon 345). The preparation method comprises the following steps:
uniformly mixing PTFE resin and PFA filler, sintering at 340 ℃ for 4hCrushing and screening the sintered product by a dry grinding method to obtain a polytetrafluoroethylene semi-sintered material; dry test with a laser particle sizer, D 10 Particle size 20 μm, D 90 Particle size 200 μm, D 50 The particle size was 65 μm.
Preparation example 3
A polytetrafluoroethylene sintering material, in particular to a polytetrafluoroethylene complete sintering material; the preparation raw materials comprise the following components in parts by weight: 70 parts of PTFE resin (Dajin M18), 30 parts of PFA filler (Teflon 345). The preparation method comprises the following steps:
uniformly mixing PTFE resin and PFA filler, sintering at 370 ℃ for 8 hours, crushing the sintered product by a dry grinding method, and screening to obtain a polytetrafluoroethylene completely sintered material; dry test with a laser particle sizer, D 10 Particle size 20 μm, D 90 Particle size 250 μm, D 50 The particle size was 100. Mu.m.
Preparation example 4
A polytetrafluoroethylene sintering material, in particular to a polytetrafluoroethylene semi-sintering material; the preparation raw materials comprise the following components in parts by weight: 90 parts of PTFE resin (Dajin M18), 10 parts of PFA filler (Teflon 345). The preparation method comprises the following steps:
uniformly mixing PTFE resin and PFA filler, sintering at 360 ℃ for 2.5 hours, crushing a sintered product by a dry grinding method, and screening to obtain a polytetrafluoroethylene semi-sintered material; dry test with a laser particle sizer, D 10 Particle size 30 μm, D 90 Particle size 220 μm, D 50 The particle size was 80 μm.
Preparation example 5
A polytetrafluoroethylene sintering material, in particular to a polytetrafluoroethylene complete sintering material; the preparation raw materials comprise the following components in parts by weight: 80 parts of PTFE resin (Dajin M18), 20 parts of silica. The preparation method comprises the following steps:
uniformly mixing PTFE resin and silicon dioxide, sintering for 6h at 380 ℃, crushing a sintered product by a dry grinding method, and screening to obtain a completely sintered polytetrafluoroethylene material; dry test with a laser particle sizer, D 10 Particle size 30 μm, D 90 Particle size of 220μm，D 50 The particle size was 70 μm.
Preparation example 6
A polytetrafluoroethylene sintering material, in particular to a polytetrafluoroethylene complete sintering material; the preparation raw materials comprise the following components in parts by weight: 95 parts of PTFE resin (Dajin M18), 5 parts of PFA filler (Teflon 345). The preparation method comprises the following steps:
uniformly mixing PTFE resin and PFA filler, sintering at 380 ℃ for 6 hours, crushing a sintered product by a dry grinding method, and screening to obtain a polytetrafluoroethylene completely sintered material; dry test with a laser particle sizer, D 10 Particle size 30 μm, D 90 Particle size 220 μm, D 50 The particle size was 70 μm.
Preparation example 7
A polytetrafluoroethylene sintering material, in particular to a polytetrafluoroethylene complete sintering material; the preparation raw materials comprise the following components in parts by weight: 68 parts of PTFE resin (Dajin M18), 32 parts of PFA filler (Teflon 345). The preparation method comprises the following steps:
uniformly mixing PTFE resin and PFA filler, sintering at 380 ℃ for 6 hours, crushing a sintered product by a dry grinding method, and screening to obtain a polytetrafluoroethylene completely sintered material; dry test with a laser particle sizer, D 10 Particle size 30 μm, D 90 Particle size 220 μm, D 50 The particle size was 70 μm.
Comparative preparation example 1
A polytetrafluoroethylene sintering material, in particular to a polytetrafluoroethylene complete sintering material, the preparation method comprises the following steps:
sintering PTFE resin (Dajin M18) for 6h at 380 ℃, crushing a sintered product by a dry grinding method, and screening to obtain a polytetrafluoroethylene completely sintered material; dry test with a laser particle sizer, D 10 Particle size 30 μm, D 90 Particle size 220 μm, D 50 The particle size was 70 μm.
Comparative preparation example 2
A polytetrafluoroethylene sintering material, in particular to a polytetrafluoroethylene complete sintering material; the preparation raw materials and the sintering method were the same as those in preparation example 1 except for short dry-milling time, and D thereof 10 Having a particle diameter of80μm，D 90 Particle size 300 μm, D 50 The particle size was 180. Mu.m.
Comparative preparation example 3
A polytetrafluoroethylene sintering material, in particular to a polytetrafluoroethylene complete sintering material; the preparation raw material and the sintering method were the same as those of preparation example 1 except that the dry-grinding time was long, and D was 10 Particle size 10 μm, D 90 Particle size 100 μm, D 50 The particle size was 40 μm.
Example 1
A polytetrafluoroethylene breathable film comprises the following components in parts by weight: 100 parts of a polytetrafluoroethylene frit (preparation example 1), 30 parts of a PTFE resin (gold M18); the preparation method comprises the following steps:
(1) Uniformly mixing a polytetrafluoroethylene sintering material and PTFE resin, adding the mixture into a mold, and molding for 30min under the pressure of 20MPa to obtain a blank;
(2) Sintering the blank obtained in the step (1), firstly heating to 320 ℃, and preserving heat for 3 hours; then heating to 380 ℃, and preserving heat for 5 hours; then cooling to 320 ℃, and preserving heat for 3 hours; finally, cooling to room temperature to obtain a sintered product;
(3) Turning the sintered product obtained in the step (2) to obtain a polytetrafluoroethylene breathable film with the thickness of 0.22mm and the width of 150 mm.
Example 2
A polytetrafluoroethylene breathable film comprises the following components in parts by weight: 100 parts of a polytetrafluoroethylene frit (preparation example 2), 20 parts of a PTFE resin (gold M18); the preparation method comprises the following steps:
(1) Uniformly mixing a polytetrafluoroethylene sintered material with PTFE resin, adding the mixture into a mold, and pressing the mixture for 40min under the pressure of 20MPa to obtain a blank;
(2) Sintering the blank obtained in the step (1), firstly heating to 300 ℃, and preserving heat for 4 hours; then heating to 350 ℃, and preserving heat for 6 hours; then cooling to 300 ℃, and preserving heat for 4 hours; finally, cooling to room temperature to obtain a sintered product;
(3) Turning the sintered product obtained in the step (2) to obtain a polytetrafluoroethylene breathable film with the thickness of 0.22mm and the width of 150 mm.
Example 3
A polytetrafluoroethylene breathable film comprises the following components in parts by weight: 80 parts of a polytetrafluoroethylene frit (preparation example 3), 40 parts of a PTFE resin (Dajin M18); the preparation method comprises the following steps:
(1) Uniformly mixing a polytetrafluoroethylene sintering material and PTFE resin, adding the mixture into a mold, and performing compression molding for 20min under the pressure of 10MPa to obtain a blank;
(2) Sintering the blank obtained in the step (1), firstly heating to 330 ℃, and keeping the temperature for 2.5 hours; then heating to 390 ℃, and preserving heat for 4 hours; then cooling to 335 ℃, and preserving heat for 2h; finally, cooling to room temperature to obtain a sintered product;
(3) Turning the sintered product obtained in the step (2) to obtain the polytetrafluoroethylene breathable film with the thickness of 0.22mm and the width of 150 mm.
Example 4
A polytetrafluoroethylene breathable film having a thickness of 0.22mm and a width of 150mm; the preparation raw materials comprise the following components in parts by weight: 100 parts of a polytetrafluoroethylene frit (preparation example 4), 20 parts of a PTFE resin (gold M18); the preparation method was the same as that in example 1.
Example 5
A polytetrafluoroethylene breathable film having a thickness of 0.22mm and a width of 150mm; the preparation raw materials comprise the following components in parts by weight: 100 parts of a polytetrafluoroethylene frit (preparation example 5), 30 parts of a PTFE resin (gold M18); the preparation method was the same as that in example 1.
Example 6
A polytetrafluoroethylene ventilated membrane, the thickness is 0.22mm, the width is 150mm; the preparation raw materials comprise the following components in parts by weight: 100 parts of a polytetrafluoroethylene frit (preparation example 1), 12 parts of a PTFE resin (gold M18); the preparation method was the same as that in example 1.
Example 7
A polytetrafluoroethylene ventilated membrane, the thickness is 0.22mm, the width is 150mm; the preparation raw materials comprise the following components in parts by weight: 60 parts of a polytetrafluoroethylene frit (preparation example 1), 40 parts of a PTFE resin (gold M18); the preparation method was the same as that in example 1.
Example 8
A polytetrafluoroethylene ventilated membrane, the thickness is 0.22mm, the width is 150mm; the preparation raw materials comprise the following components in parts by weight: 100 parts of a polytetrafluoroethylene frit (preparation example 6), 30 parts of a PTFE resin (gold M18); the preparation method was the same as that in example 1.
Example 9
A polytetrafluoroethylene breathable film having a thickness of 0.22mm and a width of 150mm; the preparation raw materials comprise the following components in parts by weight: 100 parts of a polytetrafluoroethylene frit (preparation example 7), 30 parts of a PTFE resin (gold M18); the preparation method was the same as that in example 1.
Comparative example 1
A polytetrafluoroethylene ventilated membrane, the thickness is 0.22mm, the width is 150mm; the preparation raw materials comprise the following components in parts by weight: 100 parts of a polytetrafluoroethylene frit (comparative preparation example 1), 30 parts of a PTFE resin (Large gold M18); the preparation method was the same as that in example 1.
Comparative example 2
A polytetrafluoroethylene ventilated membrane, the thickness is 0.22mm, the width is 150mm; the preparation raw materials comprise the following components in parts by weight: 100 parts of a polytetrafluoroethylene frit (comparative preparation example 2), 30 parts of a PTFE resin (Dajin M18); the preparation method was the same as that in example 1.
Comparative example 3
A polytetrafluoroethylene ventilated membrane, the thickness is 0.22mm, the width is 150mm; the preparation raw materials comprise the following components in parts by weight: 100 parts of a polytetrafluoroethylene frit (comparative preparation example 3), 30 parts of a PTFE resin (Large gold M18); the preparation method was the same as that in example 1.
Comparative example 4
A polytetrafluoroethylene breathable film comprises the following components in parts by weight: 80 parts of a polytetrafluoroethylene frit (comparative preparation example 1), 30 parts of a PTFE resin (Dajin M18), 20 parts of a PFA filler (Teflon 345); the preparation method comprises the following steps:
(1) Uniformly mixing a polytetrafluoroethylene sintering material, PTFE resin and PFA filler, adding the mixture into a mold, and molding for 30min under the pressure of 20MPa to obtain a blank;
(2) Sintering the blank obtained in the step (1), firstly heating to 320 ℃, and preserving heat for 3 hours; then heating to 380 ℃, and preserving the heat for 5 hours; then cooling to 320 ℃, and preserving heat for 3 hours; finally, cooling to room temperature to obtain a sintered product;
(3) Turning the sintered product obtained in the step (2) to obtain a polytetrafluoroethylene breathable film with the thickness of 0.22mm and the width of 150 mm.
Comparative example 5
A polytetrafluoroethylene breathable film comprises the following components in parts by weight: 110 parts of PTFE resin (Dajin M18), 20 parts of PFA filler (Teflon 345); the preparation method comprises the following steps:
(1) Uniformly mixing PTFE resin and PFA filler, adding the mixture into a mold, and molding for 30min under the pressure of 20MPa to obtain a blank;
(2) Sintering the blank obtained in the step (1), firstly heating to 320 ℃, and preserving heat for 3 hours; then heating to 380 ℃, and preserving the heat for 5 hours; then cooling to 320 ℃, and preserving heat for 3 hours; finally, cooling to room temperature to obtain a sintered product;
(3) Turning the sintered product obtained in the step (2) to obtain a polytetrafluoroethylene breathable film with the thickness of 0.22mm and the width of 150 mm.
Comparative example 6
A polytetrafluoroethylene breathable film comprises the following components in parts by weight: 100 parts of a polytetrafluoroethylene frit (preparation example 1), 30 parts of a polytetrafluoroethylene frit (comparative preparation example 1); the preparation method comprises the following steps:
(1) Uniformly mixing 2 polytetrafluoroethylene sintering materials, adding the mixture into a mold, and molding for 30min under the pressure of 20MPa to obtain a blank;
(2) Sintering the blank obtained in the step (1), firstly heating to 320 ℃, and preserving heat for 3 hours; then heating to 380 ℃, and preserving heat for 5 hours; then cooling to 320 ℃, and preserving heat for 3 hours; finally, cooling to room temperature to obtain a sintered product;
(3) Turning the sintered product obtained in the step (2) to obtain a polytetrafluoroethylene breathable film with the thickness of 0.22mm and the width of 150 mm.
The performance test of the polytetrafluoroethylene breathable films provided in examples 1 to 9 and comparative examples 1 to 6 was carried out by the following specific method:
(1) Pore diameter
The test was carried out according to the method described in standard GB/T32361-2015, in μm: soaking a sample to be detected by using low surface tension liquid to ensure that all pores are filled with wetting liquid; the sample was mounted on a jig, vented, and the gas pressure was increased stepwise. As the gas pressure increases, the surface tension of the liquid is overcome until the liquid is drained from the pores, and the relationship between the gas pressure and the gas flow rate during this process is recorded, referred to as the "wet" curve; after all the liquid is discharged, recording the relation between the gas pressure and the gas flow, and calling a dry curve; the average pore diameter is calculated by a dry curve and a wet curve.
(2) Air flux
The test was performed according to the test standard QCT 979-2014: and installing the cut sample to be tested in a clamping device, installing the clamping device in a closed metal tank, wherein one end of the metal tank is connected with an air tightness tester, and the other end of the metal tank is connected with a gas collecting device by using a gas pipe. The gas was collected using a drainage method to test the volume V and the time T required to collect the gas was recorded. The gas flux of the film was calculated as follows: k = V/(a · T); wherein K represents the average ventilation flow, mL/min/cm 2 (ii) a V represents the volume of gas collected, mL; a represents an effective area, cm 2 (ii) a T represents the gas collection time, min.
(3) Water pressure resistance
The test was performed according to the test standard QCT 979-2014: installing the cut sample to be tested in a clamping device, and adding a water column with the height of 10mm into a clamp; connecting one end of the clamping device with an air tightness tester; testing the pressure of water drop exudation within 1min under the stable air pressure; the initial pressure of the test is 30kPa, and each test is increased by 1kPa if no water seeps out until water seeps out; 5 samples were tested, and the minimum pressure without water penetration was taken as the test result.
(4) Density of
Instead of the density of the sintered product (cylindrical billet obtained in step (2) of the production method), the mass of the sintered product was weighed, the volume of the sintered product (calculated from the billet inner diameter, outer diameter and height) was measured, and the density was obtained by dividing the mass by the volume.
(5) Shrinkage rate
Cutting the sample to be measured into sample pieces with length of about 10cm and width of 1cm, and measuring the accurate length L by a ruler 0 (ii) a Placing in a 200 ℃ oven for 10min, taking out, cooling to room temperature, and measuring the length L of the film by using a ruler; shrinkage factor = (L-L) 0 )/L 0 ×100％。
(6) Tensile strength
The test was carried out according to the method described in the standard ASTM D461-87.
The test data are shown in table 1:
TABLE 1
In table 1, n.d. represents no detection; a representing the maximum range of out of the instrument.
As is clear from the property data in Table 1, in the polytetrafluoroethylene permeable films provided in examples 1 to 7 of the present invention, the polytetrafluoroethylene permeable film has a porous structure with a uniform distribution and controllable size and porosity, an average pore diameter of 0.8 to 3 μm and a density of 1.0 to 1.7g/cm, due to the mutual cooperation between the filler-containing polytetrafluoroethylene frit and the second polytetrafluoroethylene resin 3 The gas flux reaches 210-900 mL/min/cm 2 The flexible heat-shrinkable film has the following characteristics of @7kPa, water pressure resistance of 35-67 kPa, heat shrinkage rate of not more than 2.0%, tensile strength of 12.5-24 MPa, excellent air permeability, water resistance and mechanical strength, low shrinkage rate, good scale temperature property, and capability of fully meeting the application requirements of the polytetrafluoroethylene breathable film in the explosion-proof valve of a battery pack. Simultaneously, the filler in the polytetrafluoroethylene sintering material is screened and the grain size is controlled, and the polytetrafluoroethylene is sinteredThe performance of the polytetrafluoroethylene gas-permeable membrane can be further optimized by the design of the proportion of the caking materials to the polytetrafluoroethylene resin; if the filler is inorganic filler silica (example 5), the water pressure resistance of the polytetrafluoroethylene breathable film is affected. The polytetrafluoroethylene sintering material and the second polytetrafluoroethylene resin are mutually cooperated according to a specific mass ratio, so that the comprehensive performance of the polytetrafluoroethylene breathable film can be more balanced. If the amount of the polytetrafluoroethylene sintering material is too much (example 6), the film has many pores, large pore diameter and good air permeability, but the water pressure resistance is poor; if the amount of the second polytetrafluoroethylene resin is too large (example 7), the breathability of the film is affected. In addition, the mass percentage of the filler in the polytetrafluoroethylene breathable film directly affects the film performance, and if the mass percentage of the FPA filler is more than 20 percent (example 9), the breathability of the film is reduced; if the filler content is less than 5% by mass (example 8), the heat shrinkage of the polytetrafluoroethylene permeable film increases, the dimensional stability decreases, and the water pressure resistance decreases.
In the present invention, D 50 The mutual cooperation of the polytetrafluoroethylene sintering material with the grain diameter of 50-150 mu m and the polytetrafluoroethylene resin ensures that the film has a proper pore-size structure and excellent air permeability; if the preparation raw materials are all polytetrafluoroethylene sintering materials (comparative example 6), the water resistance and the mechanical strength of the film are poor; if the starting material was a combination of PTFE resin and filler without pre-sintering (comparative example 5), the film had little gas permeability. Moreover, the too high grain diameter of the polytetrafluoroethylene sintering material (comparative example 2) can cause the pore diameter of the film to be too large, the water resistance is poor, and the too small grain diameter (comparative example 3) can cause the pore diameter of the film to be small, and the air permeability is difficult to meet the requirement of pressure relief. According to the invention, the filler is added into the polytetrafluoroethylene sintering material to further improve the air permeability, water resistance and mechanical strength of the film, and if the filler is not added into the system (comparative example 1), the comprehensive performance of the film is obviously reduced; if the filler is not subjected to the pre-sintering step (comparative example 4), the filler and the PTFE polymer are difficult to be fully blended and cooperated, the film appearance has obvious non-uniform phenomenon, and the performance of the polytetrafluoroethylene breathable film cannot meet the application requirement.
The applicant states that the present invention is illustrated by the above examples of the polytetrafluoroethylene breathable film of the invention and the preparation method and application thereof, but the present invention is not limited to the above examples, i.e. it does not mean that the present invention must be implemented by the above examples. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (30)
1. The polytetrafluoroethylene breathable film is characterized by comprising the following raw materials in parts by weight: 20-100 parts of polytetrafluoroethylene sintering material and 10-40 parts of second polytetrafluoroethylene resin; the mass ratio of the polytetrafluoroethylene sintering material to the second polytetrafluoroethylene resin is 1 (0.2-0.6);
the raw materials for preparing the polytetrafluoroethylene sintered material comprise a composition of a first polytetrafluoroethylene resin and a filler, and D of the polytetrafluoroethylene sintered material 50 The grain diameter is 50-150 mu m; the filler is a meltable fluoropolymer filler which is a soluble polytetrafluoroethylene filler;
the mass of the filler is 5-20% by taking the total mass of the polytetrafluoroethylene sintered material and the second polytetrafluoroethylene resin as 100%; in the raw materials for preparing the polytetrafluoroethylene sintered material, the mass ratio of the first polytetrafluoroethylene resin to the filler is 1 (0.01-0.8), and the polytetrafluoroethylene sintered material is prepared by adopting the following method, wherein the method comprises the following steps: and uniformly mixing the first polytetrafluoroethylene resin and the filler, sintering, and then crushing a sintered product to obtain the polytetrafluoroethylene sintered material.
2. The polytetrafluoroethylene permeable film according to claim 1, wherein a mass ratio of the first polytetrafluoroethylene resin to the filler in the raw materials for preparing the polytetrafluoroethylene sintered material is 1 (0.05-0.5).
3. The polytetrafluoroethylene breathable film according to claim 1, wherein the powder density of the first polytetrafluoroethylene resin is 350 to 450g/L.
4. The polytetrafluoroethylene breathable film according to claim 1, wherein the first melting point of the first polytetrafluoroethylene resin is 340 to 350 ℃ and the second melting point is 320 to 330 ℃.
5. The polytetrafluoroethylene breathable film according to claim 1, wherein the sintered polytetrafluoroethylene material is a fully sintered polytetrafluoroethylene material and/or a semi-sintered polytetrafluoroethylene material.
6. The polytetrafluoroethylene breathable film according to claim 1, wherein the sintering temperature is in the range of 340-380 ℃.
7. The polytetrafluoroethylene breathable film according to claim 1, wherein the sintering time is 2 to 10 hours.
8. The polytetrafluoroethylene breathable film according to claim 1, wherein the polytetrafluoroethylene sintering material is a polytetrafluoroethylene fully-sintered material, the sintering temperature is 360-380 ℃ and does not include 360 ℃, and the sintering time is 5-10 h.
9. The polytetrafluoroethylene breathable film according to claim 1, wherein the polytetrafluoroethylene sintering material is a polytetrafluoroethylene semi-sintering material, and the sintering temperature is 340-360 ℃ and the sintering time is 2-4 h.
10. The polytetrafluoroethylene breathable film of claim 1, wherein the comminuting comprises any one or a combination of at least two of dry milling, water milling, or air milling.
11. The polytetrafluoroethylene vented membrane of claim 1, further comprising a sieving step after said comminuting.
12. The polytetrafluoroethylene breathable film according to claim 1, wherein D of the polytetrafluoroethylene frit is 50 The grain diameter is 60-100 μm.
13. The polytetrafluoroethylene breathable film according to claim 1, wherein D of the polytetrafluoroethylene frit is 10 The grain diameter is 10-50 μm.
14. The polytetrafluoroethylene breather membrane of claim 13, wherein D of the polytetrafluoroethylene frit is 10 The grain diameter is 20-30 μm.
15. The polytetrafluoroethylene breathable film according to claim 1, wherein D of the polytetrafluoroethylene frit is 90 The grain diameter is 150-300 mu m.
16. The polytetrafluoroethylene breather membrane of claim 15, wherein D of the polytetrafluoroethylene frit is 90 The grain diameter is 200-250 μm.
17. The polytetrafluoroethylene breathable film according to claim 1, wherein the powder density of the second polytetrafluoroethylene resin is 350 to 450g/L.
18. The polytetrafluoroethylene breathable film of claim 1, wherein D of said second polytetrafluoroethylene resin is 50 The grain diameter is 10-100 μm.
19. A polytetrafluoroethylene breathable film according to claim 1 wherein said second polytetrafluoroethylene resin has a first melting point of 340-350 ℃ and a second melting point of 320-330 ℃.
20. The polytetrafluoroethylene breathable film according to claim 1, wherein the polytetrafluoroethylene breathable film has a thickness of 0.1 to 0.5mm.
21. The polytetrafluoroethylene gas-permeable membrane according to claim 1, wherein the polytetrafluoroethylene gas-permeable membrane is a porous membrane having a pore diameter of 0.5 to 6 μm.
22. A process for the preparation of a polytetrafluoroethylene breathable film according to any of claims 1 to 21, comprising: and uniformly mixing the polytetrafluoroethylene sintered material with a second polytetrafluoroethylene resin, and then sequentially carrying out die pressing, sintering and turning to obtain the polytetrafluoroethylene breathable film.
23. The production method according to claim 22, wherein the pressure of the molding is 8 to 30MPa.
24. The production method according to claim 23, wherein the pressure of the molding is 10 to 20MPa.
25. The method of claim 22, wherein the molding time is 5 to 50min.
26. The method of claim 25, wherein the molding time is 10 to 30min.
27. The method of claim 22, wherein the sintering temperature is 300 to 400 ℃.
28. The method of claim 22, wherein the sintering time is 8 to 20 hours.
29. The method for preparing the ceramic material according to claim 22, wherein the sintering comprises the following specific steps: firstly, heating a reaction system to 300-335 ℃, and preserving heat for 2-4 h; then heating to 350-400 ℃, and preserving the heat for 4-6 h; then cooling to 300-335 ℃, and preserving heat for 2-4 h; and finally, cooling to room temperature to obtain a sintered product.
30. Use of a polytetrafluoroethylene permeable membrane according to any one of claims 1 to 21 in a waterproof component, a gas permeable component, a packaging material or a battery material.
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| GB9007304D0 (en) * | 1990-03-31 | 1990-05-30 | Gore W L & Ass Uk | Filter element |
| US5677031A (en) * | 1990-03-31 | 1997-10-14 | W. L. Gore & Associates, Inc. | Porous PTFE structures |
| US5217666A (en) * | 1991-05-29 | 1993-06-08 | Daikin Industries Ltd. | Process for producing porous polytetrafluoroethylene film |
| GB9202360D0 (en) * | 1992-02-04 | 1992-03-18 | Gore W L & Ass Uk | Ostomy filter |
| GB9606819D0 (en) * | 1996-03-30 | 1996-06-05 | Gore W L & Ass Uk | Granular-type polytetrafluoroethylene dispersions and fused articles prepared therefrom (Case B) |
| GB9606818D0 (en) * | 1996-03-30 | 1996-06-05 | Gore W L & Ass Uk | Granular-type modified polytetrafluoroethlyene dispersions and fused articles prepared therefrom (Case A) |
| GB9626399D0 (en) * | 1996-12-19 | 1997-02-05 | Gore W L & Ass Uk | High strength porous composite |
| GB2337991A (en) * | 1998-06-04 | 1999-12-08 | Gore & Ass | Fine powder type PTFE material |
| US20050238872A1 (en) * | 2004-04-23 | 2005-10-27 | Kennedy Michael E | Fluoropolymer barrier material |
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2021
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Address after: 518105 No.501, workshop 2, Jiada Industrial Park, west side of Honghu East Road, Yanchuan community, Yanluo street, Bao'an District, Shenzhen City, Guangdong Province Patentee after: Shenzhen Fuchengwei Technology Co.,Ltd. Patentee after: Contemporary Amperex Technology Co.,Ltd. Address before: 518105 No.501, workshop 2, Jiada Industrial Park, west side of Honghu East Road, Yanchuan community, Yanluo street, Bao'an District, Shenzhen City, Guangdong Province Patentee before: SHENZHEN FUTUREWAY TECHNOLOGY Co.,Ltd. Patentee before: Contemporary Amperex Technology Co.,Ltd. |
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