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CN-122011737-A - Waterproof breathable TPU film and preparation method thereof

CN122011737ACN 122011737 ACN122011737 ACN 122011737ACN-122011737-A

Abstract

The invention relates to the technical field of synthetic materials, in particular to a waterproof breathable TPU film and a preparation method thereof. The waterproof breathable TPU film comprises, by mass, 100-120 parts of TPU, 1-2 parts of sodium bicarbonate, 1.2-2 parts of citric acid monohydrate, 1-2 parts of polyvinylpyrrolidone K, 0.3-0.8 part of zinc stearate, 1-2 parts of nanocellulose, 3-5 parts of a cross-linking agent and 10-15 parts of a pore-foaming agent. The preparation method comprises the steps of S1 mixing, S2 extruding, water-cooling and granulating to obtain master batches, S3 preparing a film with the thickness of 20-30 mu m, S4 preparing a dissolved film, S5 treating a tannic acid ethanol solution, and drying to obtain the waterproof breathable TPU film. The film prepared by the invention has excellent waterproof and breathable properties, excellent mechanical properties and durability, and the preparation method has simple and efficient process, is suitable for large-scale production and is environment-friendly.

Inventors

  • HUANG TIANGUI
  • HU ZHULIN

Assignees

  • 广州佳实顺新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20260326

Claims (10)

  1. 1. The waterproof breathable TPU film is characterized by comprising, by mass, 100-120 parts of TPU, 1-2 parts of sodium bicarbonate, 1.2-2 parts of citric acid monohydrate, 30-2 parts of polyvinylpyrrolidone K, 0.3-0.8 part of zinc stearate, 1-2 parts of nanocellulose, 3-5 parts of a cross-linking agent and 10-15 parts of a pore-foaming agent.
  2. 2. The waterproof breathable TPU film according to claim 1, wherein the pore-forming agent is composed of 10-12 parts of sodium chloride and 3-5 parts of PEG-10000.
  3. 3. The waterproof breathable TPU film according to claim 1, wherein said crosslinking agent consists of 2-3 parts of urea, 1-2 parts of boric acid and 0.2-0.5 parts of monoammonium phosphate.
  4. 4. The waterproof breathable TPU film of claim 1, wherein said TPU is polyether 58887a.
  5. 5. The waterproof breathable TPU film according to claim 1, further comprising 1-2 parts of nanoscale gallic acid-zinc coordination compound, wherein the preparation method comprises the steps of dissolving gallic acid and zinc chloride in ethanol according to a molar ratio of 2:1, reacting for 1h, adding water to separate out precipitate, filtering, washing and drying to obtain the nanoscale gallic acid-zinc coordination compound.
  6. 6. The waterproof breathable TPU film according to claim 2, wherein the sodium chloride particle size is 10-20 μm.
  7. 7. The waterproof breathable TPU film according to claim 1, wherein the foaming process in the TPU film is a synergistic gradient foaming by sodium bicarbonate-citric acid monohydrate-polyvinylpyrrolidone K30, wherein polyvinylpyrrolidone migrates towards the skin layer during processing, carrying part of the foaming agent, forming a gradient distribution of small pore size of the skin layer and large pore size of the inner layer.
  8. 8. A method for preparing the waterproof breathable TPU film according to any one of claims 1 to 7, comprising the steps of: S1, adding all the components into a high-speed mixer according to a proportion, mixing for 8 minutes, and then vacuum drying to obtain a mixture; S2, adding the mixture obtained in the step S1 into a homodromous double-screw extruder, heating up in a gradient way at the temperature of 170-220 ℃, stirring, melting, extruding, water-cooling and granulating to obtain master batches; S3, adding the master batch obtained in the step S2 into a single-screw film blowing machine, setting the temperature of a charging barrel to be 180 ℃, and setting the temperature of a die head to be 180 ℃ to obtain a film with the thickness of 20-30 mu m; S4, immersing the film prepared in the step S3 into water at 40-60 ℃ to dissolve sodium chloride, and then immersing into warm water at 30-50 ℃ to dissolve PEG-10000 to obtain a dissolved film; s5, immersing the dissolved film prepared in the step S4 into a tannic acid ethanol solution with the concentration of 1-3 g/L for 0.5-2 min, and drying to obtain the waterproof breathable TPU film.
  9. 9. The method for preparing the waterproof and breathable TPU film according to claim 8, wherein the waterproof and breathable TPU film prepared in the step S5 is prepared by treating the waterproof and breathable TPU film with triethoxy-1H, 2H-tridecafluoro-N-octyl silane for 20-40 min and drying the waterproof and breathable TPU film.
  10. 10. The method for producing a waterproof and breathable TPU film according to claim 8, wherein the dissolved film produced in step S4 is transferred to a high pressure reactor, heated to 40 ℃, carbon dioxide is injected to 100bar, kept for 4 hours to allow carbon dioxide to fully permeate, then depressurized at a rate of 0.5MPa/S, further perforated, and then subjected to the treatment process of step S5.

Description

Waterproof breathable TPU film and preparation method thereof Technical Field The invention relates to the technical field of synthetic materials, in particular to a waterproof breathable TPU film and a preparation method thereof. Background Thermoplastic Polyurethane (TPU) films are widely used in the fields of outdoor clothing, medical protection, electronic product packaging and the like due to their excellent elasticity, wear resistance, low temperature resistance and processability. The ideal TPU film has the waterproof and breathable functions, namely, can block the permeation of external liquid water, and simultaneously allows the water vapor molecules such as human sweat and the like to be discharged, so that the wearing comfort is maintained. The main ways of achieving breathability of TPU films in the prior art include 1) microporous breathable processes, which allow diffusion of water vapor but block liquid water by forming a large number of interconnected submicron-sized pores in the film. However, the microporous structure is liable to be blocked or disabled by stains and washing under the action of long-term use or water pressure, and the waterproof durability is poor. 2) The hydrophilic non-porous ventilation method relies on the adsorption-diffusion-desorption of water molecules by means of hydrophilic chain segments or added hydrophilic agents in the film body. Although the method has no pore blocking problem, the ventilation efficiency is generally lower, and hydrophilic components are easy to migrate and separate out under the high-temperature and high-humidity environment, so that the performance is attenuated. CN115537139B, in particular to a waterproof breathable TPU high-low temperature film and a preparation method thereof. The waterproof breathable TPU high-low temperature film comprises a breathable waterproof film layer, a TPU foaming film layer, a netlike hot melt adhesive layer and a release film layer which are sequentially arranged from top to bottom, wherein the TPU foaming film layer is provided with a plurality of air passing through holes which are arranged at intervals, and the air passing through holes penetrate through the upper surface and the lower surface of the TPU foaming film layer. The TPU foaming high-low temperature film has the advantages of simple structure, good air permeability and water resistance, good mechanical property, convenient use, strong practicability, simple and convenient preparation method, easy control, low production cost, stable product quality and contribution to industrial mass production. But has the defects of complex multilayer composite process, low production efficiency and higher cost, and the penetrating through air holes are easy to cause liquid water leakage and have poor waterproof durability. Therefore, developing a structural compact, nonporous, waterproof and breathable TPU film is a technical problem to be solved in the field. Disclosure of Invention The invention provides a waterproof breathable TPU film which comprises, by mass, 100-120 parts of TPU, 1-2 parts of sodium bicarbonate, 1.2-2 parts of citric acid monohydrate, 1-2 parts of polyvinylpyrrolidone K, 0.3-0.8 part of zinc stearate, 1-2 parts of nanocellulose, 3-5 parts of a cross-linking agent and 10-15 parts of a pore-foaming agent. Zinc stearate acts as a dispersant and heat stabilizer and is first decomposed during extrusion to form a microcellular heat barrier around polyvinylpyrrolidone K30. The sodium bicarbonate then decomposes and the citric acid begins to melt and react with the sodium bicarbonate, the difference in decomposition temperatures forming a time gradient. Polyvinylpyrrolidone K30 has partial compatibility in the molten TPU, migrates to the film surface in the shear flow field, carrying part of the sodium bicarbonate, forming a spatial gradient. The sodium bicarbonate is decomposed to generate carbon dioxide, the citric acid is decomposed to generate carbon dioxide and release crystal water, and the water vapor is rapidly expanded at high temperature to form double foaming power. The polyvinylpyrrolidone K30 not only serves as a dispersing medium of the foaming agent, but also has an amide group which plays a role of a bubble stabilizer in the foaming process, so that bubbles are prevented from being combined, and finally, gradient pore size distribution from the surface layer to the inner layer is formed. The nanocellulose forms a three-dimensional network structure in the film, plays a remarkable role in strengthening and toughening, can refine the microphase separation structure of the TPU, and prolongs the diffusion path tortuosity of water vapor molecules, so that hydrophilic groups on the surface of the nanocellulose participate in water molecule transmission while improving the mechanical properties, and cooperatively promote moisture permeability. Further, the pore-forming agent consists of 10-12 parts of sodium chloride and 3-5 parts of