Composite waterproof and breathable film and preparation method thereof

Abstract

The application discloses a composite waterproof and breathable film and a preparation method thereof, and comprises the following steps: step S1, placing a heavy ion irradiation film into an etching machine to perform etching; step S2, taking a base layer, and attaching the heavy ion irradiation film subjected to etching in step S1 on the base layer; step S3, dissolving and mixing waterproof coating materials to obtain a mixed gel, then using a coating machine to coat the mixed gel on the heavy ion irradiation film, performing wet film forming, and peeling off the base layer after drying to obtain the composite waterproof and breathable film; and step S4, pasting a non-woven fabric as a support layer on the composite waterproof and breathable film obtained in step S3. The application has the advantages of uniform pores, good waterproof and breathable properties and the like.

Description

Technical Field

[0001] This invention belongs to the field of waterproof and breathable membrane technology, specifically relating to a composite waterproof and breathable membrane and its preparation method. Background Technology

[0002] Waterproof and breathable membranes are common consumer products used in daily life, such as packaging bags, diapers, bandages, and protective clothing. Most existing waterproof and breathable membranes are created by stretching to form pores. For example, inorganic calcium carbonate is used as a pore-forming agent, mixed with a waterproof polymer, and then stretched laterally, longitudinally, or bidirectionally through a twin-screw extruder. The locations of the pore-forming agent are treated as defect points, forming a porous structure after stretching, achieving breathability. Alternatively, a waterproof coating material is adhered to a structure such as a heavy ion irradiated membrane, and then perforated to form a waterproof and breathable membrane. Both of these methods result in uneven pore size, leading to less than ideal waterproof and breathable performance. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides a composite waterproof and breathable membrane with better waterproof and breathable performance and its preparation method.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] The preparation method of the composite waterproof and breathable membrane includes the following steps:

[0006] Step S1: Place the heavy ion irradiated film into an etching machine for etching;

[0007] Step S2: Take the substrate layer and attach the heavy ion irradiation film etched in step S1 onto the substrate layer;

[0008] Step S3: Dissolve and mix the waterproof coating material to obtain a mixed gel, then use a coating machine to coat the mixed gel onto the heavy ion irradiation membrane, form a film by wet method, and peel off the base layer after drying to obtain a composite waterproof and breathable membrane.

[0009] Step S4: Use non-woven fabric as a support layer and attach it to the composite waterproof and breathable membrane obtained in step S3.

[0010] In a preferred embodiment of the present invention, in step S1, the heavy ion irradiation film material used is any one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), and polyethersulfone (PES).

[0011] In a preferred embodiment of the present invention, in step S1, the thickness of the etched heavy ion irradiation film is 3–20 μm.

[0012] In a preferred embodiment of the present invention, in step S1, when the heavy ion irradiated film is placed in an etching machine for solution etching, the etching machine speed is 1.0 m / s, the etching solution is an 8 mol / L sodium hydroxide solution, and the etching temperature is 80°C.

[0013] In a preferred embodiment of the present invention, in step S1, after the heavy ion irradiation film is etched, a plurality of vent holes are formed, and the diameter of the vent holes is 0.1 to 10 μm.

[0014] In a preferred embodiment of the present invention, in step S2, the base layer is any one of a release film, a micro-adhesive film, or a carrier film.

[0015] In a preferred embodiment of the present invention, in step S3, the waterproof coating material is one or more of polyvinylidene fluoride (PVDF), nylon-66 (PA66), and polyethersulfone (PES).

[0016] In a preferred embodiment of the present invention, in step S3, the temperature of the coating box in the coating machine is 75°C to 105°C.

[0017] In a preferred embodiment of the present invention, in step S3, after coating the mixed gel onto the heavy ion irradiation membrane, the coated heavy ion irradiation membrane is immersed in water for 3 minutes to solidify the mixed gel.

[0018] By adopting the above technical solution, the present invention has the following beneficial effects:

[0019] In this invention, the heavy ion irradiated membrane is first etched in an etching machine to form pores. Then, a mixed gel, which is made by mixing a waterproof coating material with a polymer solution, is applied to the heavy ion irradiated membrane. The mixed gel can naturally penetrate into the pores formed by etching, thereby uniformly distributing and forming smaller pores, thus achieving higher waterproof performance and eliminating functional defects caused by uneven pores, resulting in better waterproof and breathable properties.

[0020] The composite waterproof and breathable membrane of the present invention has the following advantages:

[0021] The composite waterproof and breathable membrane of this invention is formed by chemical etching of a heavy ion irradiated membrane to create breathable pores with a diameter of 0.1-10 μm and a thickness of 3-20 μm. After being combined with a waterproof coating material such as PVDF, the mixed gel can naturally infiltrate the etched pores under gravity and be evenly distributed in the gaps (breathable pores created by chemical etching), forming even smaller micron-level breathable pores on the surface of the irradiated membrane to achieve high waterproofness. This eliminates the functional defects caused by uneven pore size in the waterproof and breathable membrane. The composite method of this invention involves coating the mixed gel made from PVDF waterproof coating material onto the etched irradiated membrane surface using a coating machine. This results in good uniformity of pore distribution, convenient processing, and the performance of the waterproof coating can be quickly adjusted by adjusting the process parameters of the coating machine.

[0022] In summary, the present invention has the advantages of producing a composite waterproof and breathable membrane with uniform pores and good waterproof and breathable properties. Attached Figure Description

[0023] Figure 1 This is a flowchart of the preparation method of the composite waterproof and breathable membrane of the present invention;

[0024] Figure 2 These are charts showing the test results of the composite waterproof and breathable membranes produced after specific implementation of Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0026] The components of the embodiments of the invention described and shown in the accompanying drawings can typically be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0027] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0030] Example 1

[0031] In this embodiment, a method for preparing a composite waterproof and breathable membrane is proposed. The prepared composite waterproof and breathable membrane has uniform waterproof and breathable pores and better waterproof and breathable properties.

[0032] like Figure 1 As shown, in one embodiment of the present invention, the method for preparing the composite waterproof and breathable membrane of the present invention includes the following steps:

[0033] Step S1: The heavy ion irradiated film is placed in an etching machine for etching. The heavy ion irradiated film material is any one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), and polyethersulfone (PES). The thickness of the etched heavy ion irradiated film is 3-20 μm. After etching, the heavy ion irradiated film forms several vent holes with a diameter of 0.1-10 μm. Specifically, when the heavy ion irradiated film is placed in the etching machine for solution etching, the etching machine speed is 1.0 m / s, the etching solution is an 8 mol / L sodium hydroxide solution, and the etching temperature is 80℃.

[0034] Step S2: Take the substrate layer and attach the heavy ion irradiation film etched in step S1 onto the substrate layer. The substrate layer is any one of release film, micro-adhesive film, or carrier film.

[0035] Step S3: Dissolve and mix the waterproof coating material to obtain a mixed gel. Specifically, take the waterproof coating material and polymer solution, then mix the waterproof coating material and polymer solution to obtain a mixed gel. Then, use a coating machine to coat the mixed gel onto the heavy ion irradiation membrane, wet-form the film, dry it, and peel off the base layer to obtain a composite waterproof and breathable membrane. The waterproof coating material is one or more of polyvinylidene fluoride (PVDF), nylon-66 (PA66), and polyethersulfone (PES). Specifically, the coating chamber temperature in the coating machine is 75℃~105℃. In step S3, after coating the mixed gel onto the heavy ion irradiation membrane, immerse the coated heavy ion irradiation membrane in water for 3 minutes to solidify the mixed gel. In this invention, the specific materials of the heavy ion irradiation membrane and the waterproof coating material can be the same or different. After obtaining the composite waterproof and breathable membrane, double-sided adhesive rings can be attached to its side for easy adhesion.

[0036] Step S4: Use non-woven fabric as a support layer and attach it to the composite waterproof and breathable membrane obtained in step S3.

[0037] The present invention also discloses a composite waterproof and breathable membrane, which is prepared according to the above-described method for preparing a composite waterproof and breathable membrane.

[0038] In this embodiment, more detailed and specific data are used for processing and preparation. Specifically, the PET film irradiated with heavy ions is placed on an etching machine for etching. The etching process parameters are as follows: the concentration of sodium hydroxide is 8 mol / L, the temperature of sodium hydroxide is 80℃, and the etching machine speed is 1.0 m / s. After etching, the etched PET film is placed on a coating machine and coated with a pre-mixed PVDF material gel. The coating process parameters are as follows: the oven temperature of the coating machine is 75~105℃, and the coating thickness is 27~30μm. After coating, the film is immersed in water at 15℃ for 3 minutes.

[0039] Comparative Example 1

[0040] The comparative example used the same preparation method as Example 1, but the specific preparation values ​​differed. Specifically, the PET film was irradiated with heavy ions and etched on an etching machine. The etching process parameters were as follows: sodium hydroxide concentration of 8 mol / L, sodium hydroxide temperature of 80°C, and etching machine speed of 1 m / s. After etching, the etched PET film was placed on a coating machine and coated with a pre-prepared PVDF mixed gel. The coating process parameters were as follows: coating machine oven temperature of 75–105°C, coating thickness of 15–17 μm, and after coating, the film was immersed in 15°C water for 3 min.

[0041] like Figure 2As shown, the difference between this comparative example and Example 1 lies in the coating thickness. In Example 1, when the immersion conditions were room temperature and immersion in water at 15°C for 3 minutes, the air permeability was better when immersed in water at 15°C for 3 minutes. In Comparative Example 1, when the immersion conditions were the same, when the immersion conditions were room temperature and immersion in water at 15°C for 3 minutes, the air permeability was better when immersed in water at 15°C for 3 minutes.

[0042] Comparative Example 2

[0043] The comparative example used the same preparation method as Example 1, but the specific preparation values ​​differed. Specifically, the PET film was irradiated with heavy ions and etched on an etching machine. The etching process parameters were as follows: sodium hydroxide concentration of 8 mol / L, sodium hydroxide temperature of 80°C, and etching machine speed of 1 m / s. After etching, the etched PET film was placed on a coating machine and coated with a pre-prepared PVDF mixed gel. The coating process parameters were as follows: coating machine oven temperature of 75–105°C, coating thickness of 15–17 μm, and after coating, the film was immersed in 5°C water for 3 min.

[0044] After completing the preparation of the composite waterproof and breathable membranes in Example 1, Comparative Example 1, and Comparative Example 2, the prepared composite waterproof and breathable membranes were tested. The test results are compared in detail below. Figure 2 The tests include pore size measurement, air permeability measurement, waterproof performance testing, thickness testing, and audio performance testing. Pore size measurement involves placing the etched PET film sample under a microscope at 3000x magnification to measure its pore size. Air permeability measurement involves placing the coated composite waterproof and breathable membrane on a leak detector and testing its air permeability under 7KPA pressure. Waterproof performance testing involves placing the coated composite waterproof and breathable membrane on a leak detector, filling the test tube connected between the leak detector and the test fixture with water, and testing for leakage within a period of time at 500KPA. Thickness testing involves measuring the thickness of the coated composite waterproof and breathable membrane using a micrometer. Audio performance testing is conducted on an audio testing instrument, analyzing the membrane material based on the dB value of audio distortion.

[0045] Figure 2 The phrase "8 passed, 2 passed" refers to the fact that in the water pressure resistance test, 2 out of 8 test samples passed. Figure 2 The comparison shows that when the coating thickness is 15-17 μm and the coating is soaked in water at 5°C for 3 minutes, more of the composite waterproof and breathable membranes of the present invention pass the waterproof test by soaking in water at 5°C for 3 minutes compared to those that are soaked at room temperature. Therefore, the composite waterproof and breathable membranes of the present invention have superior waterproof and breathable properties.

[0046] Immersion precipitation phase separation is the most common method for preparing PVDF membranes. PVDF is a semi-crystalline polymer that can form a homogeneous solution with many high-boiling-point extreme solvents at room temperature. The polymer solution is then immersed in a non-solvent coagulation bath such as water, alcohol, or ketone. At this time, the solvent in the polymer solution diffuses into the non-solvent, while the non-solvent diffuses into the polymer, forming a kinetic diffusion process. As the diffusion continues, thermodynamic liquid-liquid phase separation occurs in the system, and PVDF membranes with different morphologies and structures are formed through phase transformation.

[0047] In the process of preparing PVDF membranes by immersion precipitation, the solvent, coagulation bath composition, coagulation bath temperature, and evaporation time have a significant impact on the membrane structure and performance. It is generally believed that the weaker the interaction between the polymer and the solvent, the faster the polymer precipitation rate. The polymer forms finger-like pores when polymerized with the solvent. Studies have found that dimethylamide as a solvent forms short finger-like pores and many dispersed spherical polymer aggregates. DMAc, tetramethylurea, and trimethyl phosphate as solvents form large voids. Methylpyrrolidone and methylene sulfoxide as solvents form wide and long finger-like pores. Hexamethylphosphonamide as a solvent forms short pores and dispersed voids. Triethyl phosphate as a solvent forms a honeycomb structure without voids.

[0048] A composite material is formed by combining a heavy ion irradiated membrane as a skeleton with PVDF and other materials as a waterproof coating. After chemical etching, the ion irradiated membrane forms breathable pores of 0.1–10 μm, and then a PVDF coating is applied on it to form a waterproof and breathable membrane composite material. This waterproof and breathable material with a heavy ion irradiated substrate as a skeleton structure solves the problems of poor stability and consistency of waterproof and breathable performance, and unstable quality of existing waterproof and breathable membrane materials produced by existing technologies with e-PTFE as the main material. The composite of the waterproof coating and the irradiated membrane material improves the problems of large membrane thickness and uneven pore size, and realizes the waterproof and breathable function of the membrane material.

[0049] In this invention, the micropore density is controllable and quantifiable. By controlling the intensity of the heavy ion beam emitted by the accelerator and the speed of the irradiated object, the micropore density can be controlled, reaching up to 8,000,000 per square centimeter. The micropore size is also controllable. The polymer membrane is bombarded by high-energy heavy ions, causing its long molecular chains to break. Then, an etching solution forms micropores at the breakage points. By controlling the concentration, temperature, and film flow rate of the etching solution, the pore size can be precisely achieved from the nanometer to the micrometer level. The micropores of this invention are regular cylindrical pores, which can meet the dustproof and waterproof requirements of various products. The air permeability value of this invention is stable. Currently, PTFE microporous stretched membranes on the market use uniaxial or biaxial stretching, resulting in significant deviations in air permeability values ​​in different areas, with deviations exceeding 20%. However, due to its unique pore-forming process and precise control of micropore density and pore size, the air permeability value of this invention is very stable in different areas, with a deviation value of less than 10%.

[0050] This embodiment does not impose any limitation on the shape, material, structure, etc. of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a composite waterproof and breathable membrane, characterized in that, Includes the following steps: Step S1: Place the heavy ion irradiated film into an etching machine for etching; Step S2: Take the substrate layer and attach the heavy ion irradiation film etched in step S1 onto the substrate layer; Step S3: Dissolve and mix the waterproof coating material to obtain a mixed gel, then use a coating machine to coat the mixed gel onto the heavy ion irradiation membrane, form a film by wet method, and peel off the base layer after drying to obtain a composite waterproof and breathable membrane. Step S4: Use non-woven fabric as a support layer and attach it to the composite waterproof and breathable membrane obtained in step S3; In step S1, the heavy ion irradiation film material used is any one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), and polyethersulfone (PES). In step S1, when the heavy ion irradiated film is placed in the etching machine for solution etching, the etching machine speed is 1.0 m / s, the etching solution is an 8 mol / L sodium hydroxide solution, and the etching temperature is 80°C. In step S1, after the heavy ion irradiation film is etched, a number of vent holes are formed, and the diameter of the vent holes is 0.1 to 10 μm. In step S3, the waterproof coating material is one or more of polyvinylidene fluoride (PVDF), nylon-66 (PA66), and polyethersulfone (PES); In step S3, after coating the mixed gel onto the heavy ion irradiation membrane, the coated heavy ion irradiation membrane is immersed in water at 5°C for 3 minutes to solidify the mixed gel.

2. The method for preparing the composite waterproof and breathable membrane according to claim 1, characterized in that: In step S1, the thickness of the etched heavy ion irradiated film is 3–20 μm.

3. The method for preparing the composite waterproof and breathable membrane according to claim 1, characterized in that: In step S2, the base layer is either a release film or a carrier film.

4. The method for preparing the composite waterproof and breathable membrane according to claim 1, characterized in that: In step S3, the temperature of the coating chamber in the coating machine is 75°C to 105°C.

5. A composite waterproof and breathable membrane, characterized in that: The composite waterproof and breathable membrane is prepared according to any one of claims 1 to 4.

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