Expanded polytetrafluoroethylene-based film type fog absorbent diaphragm and preparation method thereof

Abstract

The invention discloses an expanded polytetrafluoroethylene-based film type fog absorbent diaphragm and a preparation method thereof, a support skeleton layer of the diaphragm is an expanded polytetrafluoroethylene film with a microporous structure, fog absorbent slurry forms a fog absorption functional layer on the surface of the expanded polytetrafluoroethylene film, and the fog absorbent slurry is embedded into the microporous structure to form active filling; during preparation, the solvent, the coupling agent and the fog absorbing agent powder are added into the organic binder resin, and the organic binder resin is coated into an expanded polytetrafluoroethylene film by adopting a high-precision surface controllable coating composite technology to prepare the diaphragm. Through the mode, the expanded polytetrafluoroethylene-based film type fog absorbent membrane prepared by adopting a high-precision surface controllable coating composite technology has high moisture absorption rate and lasting reversible characteristics, the desorption reversible starting condition is not harsh, the desorption rate is high, and the adsorption and desorption cycle durability is excellent; the material has the advantages of excellent flexibility, excellent mechanical properties, excellent weather resistance and excellent temperature resistance, and is suitable for the narrow space field.

Description

Technical Field

[0001] The invention relates to the technical field of desiccants, and in particular to an expanded polytetrafluoroethylene-based film-type fog absorber membrane and a preparation method thereof. Background Art

[0002] At present, the general traditional fog absorber is a powdered inorganic substance with micro-nano particle size, usually including zeolite, molecular sieve, calcium oxide, calcium chloride, magnesium oxide, magnesium chloride, sodium chloride, aluminum hydroxide and silicon dioxide. In normal operation, the moisture absorption mechanism of the fog absorber includes chemical reaction adsorption and nanoporous physical adsorption, which are specifically divided into: zeolite, molecular sieve and mesoporous materials are adsorbed by physical adsorption; alkaline earth metal oxides and water react to form hydroxides to achieve chemical adsorption; in addition, some salts with hygroscopic properties can also be used to absorb moisture. Powdered inorganic fog absorbers with micro-nano particle size have excellent moisture absorption capacity due to their excellent specific surface area, but in actual production and application cases, powdered fog absorbers will bring cumbersome operation and cleanliness problems. Powder leakage and overflow will occur during the canning process and use, affecting the appearance quality of the product and the cleanliness level of the service environment. In practical applications, powdered inorganic fog absorbers must be packaged with appropriate containers and sealing materials such as soft packaging before they can be used. In some specific narrow space application areas, they are difficult to use due to the limited volume of the corresponding external packaging containers.

[0003] In addition, most powdered inorganic fog absorbers are irreversible and cannot be recycled multiple times. When reaching the saturated equilibrium state, they cannot be desorbed, or the desorption conditions are too harsh and the reversible starting conditions cannot be reached, resulting in a high humidity in the service environment, affecting the service life of the entire device. Summary of the invention

[0004] The main technical problem solved by the present invention is to provide an expanded polytetrafluoroethylene-based thin film type fog absorber membrane and a preparation method thereof, which can achieve long-term effectiveness of moisture absorption and desorption capabilities and achieve multiple absorption and desorption cycles, thereby effectively controlling the humidity of the service environment for a long time.

[0005] In order to solve the above technical problems, a technical solution adopted by the present invention is: to provide an expanded polytetrafluoroethylene-based thin film type fog absorbent membrane, comprising: a supporting skeleton layer, a functional layer and an active filler, the functional layer is composited on at least one side surface of the supporting skeleton layer, and the active filler is embedded in the supporting skeleton layer; the supporting skeleton layer is an expanded polytetrafluoroethylene membrane with a microporous structure, the fog absorbent slurry forms a fog absorbing functional layer on at least one side surface of the expanded polytetrafluoroethylene membrane, and the fog absorbent slurry is embedded in the microporous structure to form the active filler.

[0006] In a preferred embodiment of the present invention, the expanded polytetrafluoroethylene membrane is a single-stretch membrane or a double-stretch membrane with a thickness of 5 to 300 μm and a pore size range of 0.1 to 30 μm.

[0007] In a preferred embodiment of the present invention, the film thickness is 50 to 300 μm, and the unit area weight is ≤ 200 g / m 2 .

[0008] In order to solve the above technical problems, another technical solution adopted by the present invention is: to provide a method for preparing an expanded polytetrafluoroethylene-based thin film type fog absorbent membrane, comprising the following steps: 1) Add the solvent, coupling agent and desiccant powder to the organic binder resin in proportion, mix and disperse them evenly to obtain desiccant slurry, and then further grind the desiccant slurry and collect it for later use; 2) applying the desiccant slurry in step 1) to an expanded polytetrafluoroethylene film by using a high-precision surface controllable coating composite technology, and forming a film by high-temperature drying and curing; 3) The film in step 2) is cut and precisely die-cut to obtain an expanded polytetrafluoroethylene-based thin film type fog absorbent membrane.

[0009] In a preferred embodiment of the present invention, the coupling agent is one or more of γ-glycidyloxypropyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, vinyltriethoxysilane, anilinemethyltriethoxysilane, titanate coupling agent, zirconate coupling agent, phosphorus-containing coupling agent and boron-containing coupling agent.

[0010] In a preferred embodiment of the present invention, the active aerosol absorbent powder includes one or more of zeolite, molecular sieve, calcium oxide, calcium chloride, magnesium oxide, magnesium chloride, sodium chloride, aluminum hydroxide and silicon dioxide, wherein the mass ratio of magnesium oxide and magnesium chloride added is 25 wt% to 70 wt%.

[0011] In a preferred embodiment of the present invention, the organic binder resin includes one or more of polyacrylate resin, polyurethane resin, epoxy resin, silicone-modified acrylic resin and mercapto silicone low polymer resin.

[0012] In a preferred embodiment of the present invention, the grinding times are 2-4 times, each grinding time is 10 min, and the viscosity is controlled to be ≤1500 mPa·s.

[0013] In a preferred embodiment of the present invention, the temperature for high-temperature drying and curing to form a film is 100°C ± 50°C.

[0014] In a preferred embodiment of the present invention, the weight proportions of the solvent, coupling agent, desiccant powder and organic binder resin are: 100 parts of organic binder resin; 2.5-25 parts of coupling agent; 120-200 parts of desiccant powder; and 100-250 parts of solvent.

[0015] The beneficial effects of the present invention are as follows: the present invention adopts high-precision surface controllable coating composite technology to prepare an expanded polytetrafluoroethylene-based thin film type fog absorber membrane with high moisture absorption rate and long-lasting reversible characteristics. Under the conditions of 40°C and 90%RH, the moisture absorption rate of the membrane can reach more than 140% of its own weight, and it has an excellent high moisture absorption rate; in the moisture absorption saturated state, the membrane can be placed in a 35°C environment to achieve desorption, and the desorption rate reaches more than 130%, and the reversible start-up conditions for membrane desorption are not harsh, and the desorption rate is high, and it has excellent adsorption and desorption cycle durability; it has excellent flexibility and mechanical properties, tensile strength ≥3MPa, and elongation at break ≥45%; it has excellent weather resistance and temperature resistance, and the use temperature is -60°C ~ 120°C; in addition, due to the advantages of thin thickness, small size and light weight per unit area, the present invention is suitable for moisture-proof and anti-fog treatment in narrow space fields, such as electronic equipment, precision instruments, etc., which expands its application scenarios and scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which: Figure 1 It is a structural schematic diagram of a preferred embodiment of the expanded polytetrafluoroethylene-based thin film type fog absorbent diaphragm of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0020] In the description of the present invention, it should be noted that the terms "front", "rear", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed when in use, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0021] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In the present invention, unless otherwise clearly specified and limited, a first feature being above or below a second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. Moreover, a first feature being above, above, and above a second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being below, below, and below a second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0023] See also Figure 1 , the embodiment of the present invention includes: Embodiment 1:

[0024] An expanded polytetrafluoroethylene-based thin film type fog absorber membrane comprises: a supporting skeleton layer 2, a functional layer 1 and an active filler, wherein the functional layer 1 is composited on at least one side surface of the supporting skeleton layer 2. In the present invention, the functional layer 1 is composited on both the upper and lower sides of the supporting skeleton layer 2, and the active filler is embedded in the supporting skeleton layer 2.

[0025] In the present invention, the supporting skeleton layer 2 is an expanded polytetrafluoroethylene membrane with a microporous structure, and the demisting agent slurry forms a demisting functional layer 1 on the upper and lower surfaces of the expanded polytetrafluoroethylene membrane. The demisting agent slurry is embedded in the microporous structure to form active filling.

[0026] Among them, the expanded polytetrafluoroethylene membrane is a single-drawn membrane or a double-drawn membrane with a thickness of 5 to 300 μm. The pore size of the expanded polytetrafluoroethylene film ranges from 0.1 to 30 μm. There are hundreds of millions of irregularly shaped, staggered and crossed three-dimensional microporous air-permeable gaps per square centimeter. The material has a large number of interpenetrating microporous gaps, which have certain air permeability and moisture permeability.

[0027] The film thickness is 50 ~ 300 μm, and the unit area weight is ≤200 g / m 2 . It has excellent flexibility and mechanical properties, with tensile strength ≥3 MPa and elongation at break ≥45%; it has excellent weather resistance and temperature resistance, and the operating temperature is -60℃ ~120℃; due to its thin thickness, small size and light weight per unit area, it is suitable for moisture-proof and anti-fog treatment in small spaces, such as electronic equipment and precision instruments, which expands its application scenarios and scope of application.

[0028] The method for preparing the expanded polytetrafluoroethylene-based thin film type fog absorbent membrane of the present invention comprises the following steps: 150 parts of solvent, 10 parts of coupling agent and 140 parts of desiccant powder were added to 100 parts of organic binder resin according to the mass fraction, mixed and dispersed evenly, and desiccant slurry was obtained. The desiccant slurry was further ground, ground twice, and each grinding time was 10 min to prepare desiccant slurry, and the viscosity was measured to be 1300 mPa·s. The desiccant slurry was coated on expanded polytetrafluoroethylene film by high-precision surface controllable coating composite technology, dried and cured at 120°C to form a film, and then the film was cut and precisely die-cut to obtain an expanded polytetrafluoroethylene-based film-type desiccant membrane with a thickness of 160 μm and a unit area weight of 150 g / m 2 . Embodiment 2:

[0029] An expanded polytetrafluoroethylene-based thin film type fog absorber membrane comprises: a supporting skeleton layer 2, a functional layer 1 and an active filler, wherein the functional layer 1 is composited on at least one side surface of the supporting skeleton layer 2. In the present invention, the functional layer 1 is composited on both the upper and lower sides of the supporting skeleton layer 2, and the active filler is embedded in the supporting skeleton layer 2.

[0030] In the present invention, the supporting skeleton layer 2 is an expanded polytetrafluoroethylene membrane with a microporous structure, and the demisting agent slurry forms a demisting functional layer 1 on the upper and lower surfaces of the expanded polytetrafluoroethylene membrane. The demisting agent slurry is embedded in the microporous structure to form active filling.

[0031] Among them, the expanded polytetrafluoroethylene membrane is a single-drawn membrane or a double-drawn membrane with a thickness of 5 to 300 μm. The pore size of the expanded polytetrafluoroethylene film ranges from 0.1 to 30 μm. There are hundreds of millions of irregularly shaped, staggered and crossed three-dimensional microporous air-permeable gaps per square centimeter. The material has a large number of interpenetrating microporous gaps, which have certain air permeability and moisture permeability.

[0032] The film thickness is 50 ~ 300 μm, and the unit area weight is ≤200 g / m 2 . It has excellent flexibility and mechanical properties, with tensile strength ≥3 MPa and elongation at break ≥45%; it has excellent weather resistance and temperature resistance, and the operating temperature is -60℃ ~120℃; due to its thin thickness, small size and light weight per unit area, it is suitable for moisture-proof and anti-fog treatment in small spaces, such as electronic equipment and precision instruments, which expands its application scenarios and scope of application.

[0033] The method for preparing the expanded polytetrafluoroethylene-based thin film type fog absorbent membrane of the present invention comprises the following steps: 150 parts of solvent, 10 parts of coupling agent and 140 parts of desiccant powder were added to 100 parts of organic binder resin according to the mass fraction, mixed and dispersed evenly, and desiccant slurry was obtained. The desiccant slurry was further ground for 4 times, each time for 10 minutes, to prepare desiccant slurry, and the viscosity was measured to be 1150 mPa·s. The desiccant slurry was coated on expanded polytetrafluoroethylene film by high-precision surface controllable coating composite technology, dried and cured at 120°C to form a film, and then the film was cut and precisely die-cut to obtain an expanded polytetrafluoroethylene-based film-type desiccant membrane with a thickness of 140 μm and a unit area weight of 135 g / m 2 . Embodiment 3:

[0034] An expanded polytetrafluoroethylene-based thin film type fog absorber membrane comprises: a supporting skeleton layer 2, a functional layer 1 and an active filler, wherein the functional layer 1 is composited on at least one side surface of the supporting skeleton layer 2. In the present invention, the functional layer 1 is composited on both the upper and lower sides of the supporting skeleton layer 2, and the active filler is embedded in the supporting skeleton layer 2.

[0035] In the present invention, the supporting skeleton layer 2 is an expanded polytetrafluoroethylene membrane with a microporous structure, and the demisting agent slurry forms a demisting functional layer 1 on the upper and lower surfaces of the expanded polytetrafluoroethylene membrane. The demisting agent slurry is embedded in the microporous structure to form active filling.

[0036] Among them, the expanded polytetrafluoroethylene membrane is a single-drawn membrane or a double-drawn membrane with a thickness of 5 to 300 μm. The pore size of the expanded polytetrafluoroethylene film ranges from 0.1 to 30 μm. There are hundreds of millions of irregularly shaped, staggered and crossed three-dimensional microporous air-permeable gaps per square centimeter. The material has a large number of interpenetrating microporous gaps, which have certain air permeability and moisture permeability.

[0037] The film thickness is 50 ~ 300 μm, and the unit area weight is ≤200 g / m 2 . It has excellent flexibility and mechanical properties, with tensile strength ≥3 MPa and elongation at break ≥45%; it has excellent weather resistance and temperature resistance, and the operating temperature is -60℃ ~120℃; due to its thin thickness, small size and light weight per unit area, it is suitable for moisture-proof and anti-fog treatment in small spaces, such as electronic equipment and precision instruments, which expands its application scenarios and scope of application.

[0038] The method for preparing the expanded polytetrafluoroethylene-based thin film type fog absorbent membrane of the present invention comprises the following steps: 110 parts of solvent, 15 parts of coupling agent and 150 parts of desiccant powder were added to 100 parts of organic binder resin according to mass fractions, mixed and dispersed evenly to obtain desiccant slurry, and then the desiccant slurry was further ground, ground twice, each grinding time was 10 min, to prepare desiccant slurry, and the viscosity was measured to be 1430 mPa·s. The desiccant slurry was coated on expanded polytetrafluoroethylene film by high-precision surface controllable coating composite technology, dried and cured at 120°C to form a film, and then the film was cut and precisely die-cut to obtain an expanded polytetrafluoroethylene-based film-type desiccant membrane with a thickness of 255 μm and a unit area weight of 192 g / m 2 . Embodiment 4:

[0039] An expanded polytetrafluoroethylene-based thin film type fog absorber membrane comprises: a supporting skeleton layer 2, a functional layer 1 and an active filler, wherein the functional layer 1 is composited on at least one side surface of the supporting skeleton layer 2. In the present invention, the functional layer 1 is composited on both the upper and lower sides of the supporting skeleton layer 2, and the active filler is embedded in the supporting skeleton layer 2.

[0040] In the present invention, the supporting skeleton layer 2 is an expanded polytetrafluoroethylene membrane with a microporous structure, and the demisting agent slurry forms a demisting functional layer 1 on the upper and lower surfaces of the expanded polytetrafluoroethylene membrane. The demisting agent slurry is embedded in the microporous structure to form active filling.

[0041] Among them, the expanded polytetrafluoroethylene membrane is a single-drawn membrane or a double-drawn membrane with a thickness of 5 to 300 μm. The pore size of the expanded polytetrafluoroethylene film ranges from 0.1 to 30 μm. There are hundreds of millions of irregularly shaped, staggered and crossed three-dimensional microporous air-permeable gaps per square centimeter. The material has a large number of interpenetrating microporous gaps, which have certain air permeability and moisture permeability.

[0042] The film thickness is 50 ~ 300 μm, and the unit area weight is ≤200 g / m 2 . It has excellent flexibility and mechanical properties, with tensile strength ≥3 MPa and elongation at break ≥45%; it has excellent weather resistance and temperature resistance, and the operating temperature is -60℃ ~120℃; due to its thin thickness, small size and light weight per unit area, it is suitable for moisture-proof and anti-fog treatment in small spaces, such as electronic equipment and precision instruments, which expands its application scenarios and scope of application.

[0043] The method for preparing the expanded polytetrafluoroethylene-based thin film type fog absorbent membrane of the present invention comprises the following steps: 110 parts of solvent, 15 parts of coupling agent and 150 parts of desiccant powder were added to 100 parts of organic binder resin according to the mass fraction, mixed and dispersed evenly, and desiccant slurry was obtained. The desiccant slurry was further ground for 4 times, each time for 10 min, to prepare desiccant slurry, and the viscosity was measured to be 1380 mPa·s. The desiccant slurry was coated on expanded polytetrafluoroethylene film by high-precision surface controllable coating composite technology, dried and cured at 120°C to form a film, and then the film was cut and precisely die-cut to obtain an expanded polytetrafluoroethylene-based film-type desiccant membrane with a thickness of 225 μm and a unit area weight of 180 g / m 2 . Embodiment 5:

[0044] An expanded polytetrafluoroethylene-based thin film type fog absorber membrane comprises: a supporting skeleton layer 2, a functional layer 1 and an active filler, wherein the functional layer 1 is composited on at least one side surface of the supporting skeleton layer 2. In the present invention, the functional layer 1 is composited on both the upper and lower sides of the supporting skeleton layer 2, and the active filler is embedded in the supporting skeleton layer 2.

[0045] In the present invention, the supporting skeleton layer 2 is an expanded polytetrafluoroethylene membrane with a microporous structure, and the demisting agent slurry forms a demisting functional layer 1 on the upper and lower surfaces of the expanded polytetrafluoroethylene membrane. The demisting agent slurry is embedded in the microporous structure to form active filling.

[0046] Among them, the expanded polytetrafluoroethylene membrane is a single-drawn membrane or a double-drawn membrane with a thickness of 5 to 300 μm. The pore size of the expanded polytetrafluoroethylene film ranges from 0.1 to 30 μm. There are hundreds of millions of irregularly shaped, staggered and crossed three-dimensional microporous air-permeable gaps per square centimeter. The material has a large number of interpenetrating microporous gaps, which have certain air permeability and moisture permeability.

[0047] The film thickness is 50 ~ 300 μm, and the unit area weight is ≤200 g / m 2 . It has excellent flexibility and mechanical properties, with tensile strength ≥3 MPa and elongation at break ≥45%; it has excellent weather resistance and temperature resistance, and the operating temperature is -60℃ ~120℃; due to its thin thickness, small size and light weight per unit area, it is suitable for moisture-proof and anti-fog treatment in small spaces, such as electronic equipment and precision instruments, which expands its application scenarios and scope of application.

[0048] The method for preparing the expanded polytetrafluoroethylene-based thin film type fog absorbent membrane of the present invention comprises the following steps: 190 parts of solvent, 10 parts of coupling agent and 130 parts of desiccant powder were added to 100 parts of organic binder resin according to the mass fraction, mixed and dispersed evenly, and desiccant slurry was obtained. The desiccant slurry was further ground for 4 times, each time for 10 minutes, to prepare desiccant slurry, and the viscosity was measured to be 900 mPa·s. The desiccant slurry was coated on the expanded polytetrafluoroethylene film by high-precision surface controllable coating composite technology, and then dried and cured at 120°C to form a film. Then, the film was cut and precisely die-cut to obtain an expanded polytetrafluoroethylene-based film-type desiccant membrane with a thickness of 110 μm and a unit area weight of 100 g / m 2 .

[0049] In the above embodiments 1-5, the coupling agent is one or more of γ-glycidyloxypropyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, vinyltriethoxysilane, anilinemethyltriethoxysilane, titanate coupling agent, zirconate coupling agent, phosphorus-containing coupling agent and boron-containing coupling agent, and more preferably γ-(methacryloyloxy)propyltrimethoxysilane.

[0050] The active aerosol absorbent powder includes one or more of zeolite, molecular sieve, calcium oxide, calcium chloride, magnesium oxide, magnesium chloride, sodium chloride, aluminum hydroxide and silicon dioxide, among which magnesium oxide and magnesium chloride are preferred, and the added mass ratio is 25 wt% to 70wt%.

[0051] The organic binder resin includes one or more of polyacrylate resin, polyurethane resin, epoxy resin, silicone-modified acrylic resin and mercapto silicone low polymer resin.

[0052] The expanded polytetrafluoroethylene-based thin film type fog absorber membrane prepared by the above preparation method replaces the traditional fog absorber powder, overcomes the filling difficulty, powder overflow and powder leakage problems of the traditional powdered fog absorber, and can be used in fields with high cleanliness requirements.

[0053] The performance of the expanded polytetrafluoroethylene-based thin film fog absorber membrane prepared in Examples 1-5 above was tested, as shown in Table 1 for details.

[0054] Table 1 Performance of expanded polytetrafluoroethylene film-type fog absorbent membrane sample Grinding times (times) Viscosity (mPa·s) Thickness (μm) <![CDATA[Grammage per unit area (g / m 2 )]]> Moisture absorption rate (%) Desorption rate (%) Example 1 2 1300 160 150 157.0 149.5 Example 2 4 1150 140 135 152.5 141.0 Example 3 2 1430 255 192 170.5 163.5 Example 4 4 1380 225 180 165.8 153.5 Example 5 4 900 110 100 142.0 135.8 It can be seen that the expanded polytetrafluoroethylene-based thin film type fog absorbent diaphragm with high moisture absorption rate and long-lasting reversible characteristics is prepared by high-precision surface controllable coating composite technology. Under the conditions of 40°C and 90%RH, the moisture absorption rate of the diaphragm can reach more than 140% of its own weight, and it has excellent high moisture absorption rate; in the moisture saturated state, the diaphragm can be placed in a 35°C environment to achieve desorption, and the desorption rate reaches more than 130%. The reversible starting conditions for diaphragm desorption are not harsh, the desorption rate is high, and it has excellent adsorption and desorption cycle durability, so that the humidity of the service environment can be effectively controlled for a long time.

[0055] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An expanded polytetrafluoroethylene-based film-type fog absorbent membrane, characterized in that: include: A support skeleton layer, a functional layer and an active filler, wherein the functional layer is composited on at least one side surface of the support skeleton layer, and the active filler is embedded in the support skeleton layer; The supporting skeleton layer is an expanded polytetrafluoroethylene membrane with a microporous structure, the defogging agent slurry forms a defogging functional layer on at least one side surface of the expanded polytetrafluoroethylene membrane, and the defogging agent slurry is embedded in the microporous structure to form active filling.

2. The expanded polytetrafluoroethylene-based thin film type fog absorbent membrane according to claim 1, characterized in that: The expanded polytetrafluoroethylene membrane is a single-stretch membrane or a double-stretch membrane with a thickness of 5 to 300 μm and a pore size range of 0.1 to 30 μm.

3. The expanded polytetrafluoroethylene-based thin film type fog absorbent membrane according to claim 1, characterized in that: The film thickness is 50 ~ 300 μm, and the unit area weight is ≤200 g / m 2 .

4. The method for preparing the expanded polytetrafluoroethylene-based thin film type fog absorbent membrane according to claim 1, characterized in that: The following steps are involved: 1) Add the solvent, coupling agent and desiccant powder to the organic binder resin in proportion, mix and disperse them evenly to obtain desiccant slurry, and then further grind the desiccant slurry and collect it for later use; 2) applying the desiccant slurry in step 1) to an expanded polytetrafluoroethylene film by using a high-precision surface controllable coating composite technology, and forming a film by high-temperature drying and curing; 3) The film in step 2) is cut and precisely die-cut to obtain an expanded polytetrafluoroethylene-based thin film type fog absorbent membrane.

5. The method for preparing the expanded polytetrafluoroethylene-based thin film type fog absorbent membrane according to claim 4, characterized in that: The coupling agent is one or more of γ-glycidyloxypropyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, vinyltriethoxysilane, anilinemethyltriethoxysilane, titanate coupling agent, zirconate coupling agent, phosphorus-containing coupling agent and boron-containing coupling agent.

6. The method for preparing the expanded polytetrafluoroethylene-based thin film type fog absorbent membrane according to claim 4, characterized in that: The active aerosol absorbent powder includes one or more of zeolite, molecular sieve, calcium oxide, calcium chloride, magnesium oxide, magnesium chloride, sodium chloride, aluminum hydroxide and silicon dioxide, wherein the mass ratio of magnesium oxide and magnesium chloride is 25 wt% to 70 wt%.

7. The method for preparing the expanded polytetrafluoroethylene-based thin film type fog absorbent membrane according to claim 4, characterized in that: The organic binder resin includes one or more of polyacrylate resin, polyurethane resin, epoxy resin, silicone-modified acrylic resin and mercapto silicone low polymer resin.

8. The method for preparing the expanded polytetrafluoroethylene-based thin film type fog absorbent membrane according to claim 4, characterized in that: The grinding times are 2-4 times, each grinding time is 10 min, and the viscosity is controlled to be ≤1500 mPa·s.

9. The method for preparing the expanded polytetrafluoroethylene-based thin film type fog absorbent membrane according to claim 4, characterized in that: The temperature for high temperature drying and curing to form a film is 100℃±50℃.

10. The method for preparing the expanded polytetrafluoroethylene-based thin film type fog absorbent membrane according to claim 4, characterized in that: The weight proportions of the solvent, coupling agent, desiccant powder and organic binder resin are respectively: 100 parts of organic binder resin; 2.5-25 parts of coupling agent; 120-200 parts of desiccant powder; and 100-250 parts of solvent.

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