A polymer breathable film material and its preparation method

Abstract

The present invention discloses a polymer breathable film material and a preparation method thereof, comprising the following components in parts by weight: 2.6 - 3.1 parts of ε-caprolactone, 27 - 30 parts of L-lactide, and 0.6 - 0.9 parts of metal-polyphenol network-coated fiber crystals. It is proposed to improve the gas permeability of the polylactic acid material by preparing a star initiator from ε-caprolactone, and at the same time use microcrystalline cellulose to prepare metal-polyphenol network-coated fiber crystals as a reinforcing agent, thereby achieving improvements in mechanical properties and antibacterial properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and specifically refers to a polymer breathable film material and a preparation method thereof. Background Art

[0002] At present, most of the film materials used for packaging are non-biodegradable or petroleum-based plastics, such as polyvinylidene chloride, polystyrene, and polyvinyl chloride. With the development of society, the pressure on the environment caused by the widespread application of petroleum-based polymers in the packaging of various products is increasing day by day, and problems such as global warming and white pollution have also followed; with the rapid development of polymer materials and the continuous improvement of consumer demands, it is urgent to develop environmentally friendly degradable packaging materials to replace traditional petroleum-based plastics. Polylactic acid, starch, methyl cellulose, chitosan, soy protein, gelatin, and polyhydroxyalkanoates are environmentally friendly biomaterials. Among them, polylactic acid is a transparent, crystalline, and compostable synthetic polymer with excellent properties such as high mechanical strength, strong thermoplasticity, and good heat resistance. It has been widely used in packaging fields such as shopping bags, fruit boxes, yogurt, and disposable beverage cups. Its raw materials can be produced by fermenting agricultural products or by-products such as corn, wheat, and rice, and can be completely decomposed by microorganisms in nature. Therefore, as a completely biodegradable and renewable environmental protection material, it has received wide attention.

[0003] The current existing technologies mainly have the following problems: Currently, the gas permeability, mechanical properties, and antibacterial properties of polymer films are not good. Summary of the Invention

[0004] In view of the above situation, to overcome the defects of the prior art, the present invention provides a polymer breathable film material and a preparation method thereof. To solve the problem of poor gas permeability of polymer films, the present invention proposes to prepare a star initiator through ε-caprolactone to improve the gas permeability of polylactic acid materials, and at the same time use microcrystalline cellulose to prepare metal-polyphenol network-coated fiber crystals as reinforcing agents to further improve the mechanical properties and antibacterial properties.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: The present invention proposes a polymer breathable film material, and the polymer breathable film material comprises the following components in parts by weight: 2.6 - 3.1 parts of ε-caprolactone, 27 - 30 parts of L-lactide, and 0.6 - 0.9 parts of metal-polyphenol network-coated fiber crystals.

[0006] Preferably, the preparation method of the metal-polyphenol network-coated fiber crystals comprises the following steps:

[0007] (1) Add microcrystalline cellulose to 65 wt% sulfuric acid solution at an addition amount of 0.09 - 0.11 g / mL, stir in a water bath, then add 5 times the volume of distilled water to stop acid hydrolysis, centrifuge to obtain the precipitate, and prepare it into a 0.1 wt% suspension with deionized water, dialyze with deionized water until the pH is neutral, and rotary evaporate at 50 °C to obtain a 0.4 wt% nanocrystalline cellulose suspension;

[0008] (2) Mix 3-aminopropyltriethoxysilane and 80 wt% ethanol evenly to obtain a modifier, then mix the 0.4 wt% nanocrystalline cellulose suspension obtained in step (1) with the modifier evenly, stir magnetically at 50 rpm for 2 h, adjust the pH to 3 with acetic acid, centrifuge to obtain the precipitate, wash with 95 wt% ethanol, and dry to obtain modified nanocrystalline cellulose;

[0009] After 3-aminopropyltriethoxysilane hydrolyzes and dehydrates and condenses, it forms hydrogen bonds with the hydroxyl groups on the surface or dehydrates and condenses to form ether bonds;

[0010] (3) Prepare the modified nanocrystalline cellulose obtained in step (2) into a 0.1 wt% modified nanocrystalline cellulose suspension, add zinc chloride, mix evenly, then add procyanidin with twice the molar amount of zinc chloride to obtain a mixed solution, then add a 3-morpholinopropanesulfonic acid buffer solution with the same volume as the mixed solution and a pH of 8, shake and react at 800 rpm for 1 - 1.5 h, centrifuge at 11000 rpm for 10 min to obtain the precipitate, filter, and wash with deionized water to obtain metal-polyphenol network-coated fiber crystals.

[0011] Preferably, in step (1), the water bath stirring temperature is 45 - 55 °C and the time is 1.5 - 2.5 h;

[0012] Preferably, in step (1), the centrifugation speed is 11000 - 12000 rpm and the time is 8 - 12 min.

[0013] Preferably, in step (2), the volume ratio of 3-aminopropyltriethoxysilane to 80 wt% ethanol is 1:0.5 - 0.6;

[0014] Preferably, in step (2), the volume ratio of the 0.4 wt% nanocrystalline cellulose suspension obtained in step (1) to the modifier is 1:0.3 - 0.4;

[0015] Preferably, in step (2), the centrifugation speed is 11000 - 12000 rpm and the time is 8 - 12 min.

[0016] Preferably, in step (3), the addition amount of zinc chloride is 0.12 - 0.14 mmol / L.

[0017] The present invention also provides a method for preparing a polymer breathable film material, which specifically includes the following steps:

[0018] S1. Add ε-caprolactone into a reactor, add glycerol and stannous octoate, heat and react under argon protection, cool to room temperature, wash with 95wt% ethanol, and dry to obtain a star initiator;

[0019] S2. Add L-lactide into a reactor, then add the star initiator obtained in S1 and stannous octoate, heat and react under argon protection, cool to room temperature, wash with 95wt% ethanol, and dry to obtain a copolymer;

[0020] S3. Dissolve the copolymer obtained in S2 in chloroform, then add metal-polyphenol network-coated fiber crystals, mix evenly, pour into a polystyrene dish, and dry under vacuum to obtain a polymer breathable film material.

[0021] Preferably, in S1, the mass ratio of ε-caprolactone, glycerol and stannous octoate is 30:0.6 - 0.8:1 - 1.2;

[0022] Preferably, in S1, the heating reaction temperature is 120 - 130°C and the time is 5 - 6h.

[0023] Preferably, in S2, the mass ratio of L-lactide, star initiator and stannous octoate is 20:2 - 2.2:0.1 - 0.12;

[0024] Preferably, in S2, the heating reaction temperature is 120 - 130°C and the time is 30 - 36h.

[0025] Preferably, in S3, the addition amount of the copolymer obtained in S2 in chloroform is 0.019 - 0.021 g / mL.

[0026] The beneficial effects achieved by the present invention are as follows: The present invention uses ε-caprolactone as a monomer, glycerol as a trifunctional initiator, and stannous octoate as a catalyst to synthesize a three-armed star polymer, namely a star initiator, in an argon atmosphere. Subsequently, using the three-armed star polymer as an initiator, L-lactide as a monomer, and stannous octoate as a catalyst, a copolymer is synthesized in an argon atmosphere, which promotes the formation of a microphase separation microstructure and establishes a microphase separation structure with a sea-island morphology as a gas permeation channel, improving the breathability of the film material; preparing nano microcrystalline cellulose with amino groups on the surface, namely modified nano microcrystalline cellulose, from microcrystalline cellulose and 3-aminopropyltriethoxysilane, which improves the surface metal ion adsorption ability, promotes the polymerization of procyanidins on the surface to form metal-polyphenol network-coated nano microcrystalline cellulose, obtaining metal-polyphenol network-coated fiber crystals. At the same time, using it as a reinforcing agent endows the material with good antibacterial properties while improving the mechanical properties of the film material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a result graph of the air permeability test for Examples 1 - 3 and Comparative Example 1 of the present invention;

[0028] Figure 2 It is a result graph of the mechanical property test for Examples 1 - 3 and Comparative Example 2 of the present invention;

[0029] Figure 3 It is a result graph of the antibacterial property test for Examples 1 - 3 and Comparative Examples 2 - 3 of the present invention.

[0030] The drawings are used to provide further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0032] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to the described content can be applied to the present invention. The preferred implementation methods and materials described herein are only for demonstration purposes, but cannot limit the content of this application.

[0033] The experimental methods in the following embodiments are all conventional methods unless otherwise specified; the test materials used in the following embodiments are all obtained from commercial channels unless otherwise specified.

[0034] Example 1

[0035] A polymer breathable film material comprises the following components in parts by weight: 2.6 parts of ε - caprolactone, 27 parts of L - lactide, and 0.6 part of metal - polyphenol network - coated fiber crystals.

[0036] The preparation method of the metal - polyphenol network - coated fiber crystals comprises the following steps:

[0037] (1) Add microcrystalline cellulose to a 65 wt% sulfuric acid solution at an addition amount of 0.09 g / mL, stir in a water bath at 45 °C for 1.5 h, then add 5 times the volume of distilled water to stop the acid hydrolysis. Centrifuge at 11000 rpm for 8 min to obtain the precipitate, and prepare it into a 0.1 wt% suspension with deionized water. Dialyze with deionized water until the pH is neutral, and rotary evaporate at 50 °C to obtain a nano-crystalline cellulose suspension with a concentration of 0.4 wt%.

[0038] (2) Mix 3-aminopropyltriethoxysilane and 80 wt% ethanol in a volume ratio of 1:0.5 to obtain a modifier. Then mix the 0.4 wt% nano-crystalline cellulose suspension obtained in step (1) with the modifier in a volume ratio of 1:0.3, stir magnetically at 50 rpm for 2 h, adjust the pH to 3 with acetic acid, centrifuge at 11000 rpm for 8 min to obtain the precipitate, wash with 95 wt% ethanol, and dry to obtain modified nano-crystalline cellulose.

[0039] (3) Prepare the modified nano-crystalline cellulose obtained in step (2) into a 0.1 wt% modified nano-crystalline cellulose suspension, add zinc chloride at an addition amount of 0.12 mmol / L, mix evenly, then add procyanidin with twice the molar amount of zinc chloride to obtain a mixture. Subsequently, add a 3-morpholinopropanesulfonic acid buffer solution with a pH of 8 equal to the volume of the mixture, shake and react at 800 rpm for 1 h, centrifuge at 11000 rpm for 10 min to obtain the precipitate, filter, and wash with deionized water to obtain metal-polyphenol network-coated fiber crystals.

[0040] The present invention also provides a preparation method of a polymer breathable film material, which specifically includes the following steps:

[0041] S1. Add ε-caprolactone to a reactor, add glycerol and stannous octoate. The mass ratio of ε-caprolactone, glycerol and stannous octoate is 30:0.6:1. Heat and react at 120 °C for 5 h under argon protection, cool to room temperature, wash with 95 wt% ethanol, and dry to obtain a star initiator.

[0042] S2. Add L-lactide to a reactor, then add the star initiator obtained in S1 and stannous octoate. The mass ratio of L-lactide, star initiator and stannous octoate is 20:2:0.1. Heat and react at 120 °C for 30 h under argon protection, cool to room temperature, wash with 95 wt% ethanol, and dry to obtain a copolymer.

[0043] S3. Dissolve the copolymer obtained in S2 in chloroform at an addition amount of 0.019 g / mL, then add metal-polyphenol network-coated fiber crystals, mix evenly, pour into a polystyrene plate, and dry in vacuum to obtain a polymer breathable film material.

[0044] Example 2

[0045] A polymeric breathable thin film material comprises the following components in parts by weight: 3.1 parts of ε-caprolactone, 30 parts of L-lactide, and 0.9 part of metal-polyphenol network-coated fiber crystals.

[0046] A preparation method of metal-polyphenol network-coated fiber crystals comprises the following steps:

[0047] (1) Microcrystalline cellulose is added to a 65 wt% sulfuric acid solution at an addition amount of 0.11 g / mL, stirred in a water bath at 55 °C for 2.5 h, then 5 times the volume of distilled water is added to stop acid hydrolysis, centrifuged at 12000 rpm for 12 min to obtain a precipitate, and formulated into a 0.1 wt% suspension with deionized water, dialyzed with deionized water until the pH is neutral, and rotary evaporated at 50 °C to obtain a 0.4 wt% nano-microcrystalline cellulose suspension;

[0048] (2) 3-aminopropyltriethoxysilane and 80 wt% ethanol are mixed uniformly at a volume ratio of 1:0.6 to obtain a modifier, then the 0.4 wt% nano-microcrystalline cellulose suspension obtained in step (1) is mixed uniformly with the modifier at a volume ratio of 1:0.4, magnetically stirred at 50 rpm for 2 h, adjusted to pH 3 with acetic acid, centrifuged at 12000 rpm for 12 min to obtain a precipitate, washed with 95 wt% ethanol, and dried to obtain modified nano-microcrystalline cellulose;

[0049] (3) The modified nano-microcrystalline cellulose obtained in step (2) is formulated into a 0.1 wt% modified nano-microcrystalline cellulose suspension, zinc chloride is added at an addition amount of 0.14 mmol / L, after mixing uniformly, procyanidin with twice the molar amount of zinc chloride is added to obtain a mixed solution, then a 3-morpholinopropanesulfonic acid buffer solution with a pH of 8 equal to the volume of the mixed solution is added, shaken and reacted at 800 rpm for 1.5 h, centrifuged at 11000 rpm for 10 min to obtain a precipitate, filtered, and washed with deionized water to obtain metal-polyphenol network-coated fiber crystals.

[0050] The present invention also provides a preparation method of a polymeric breathable thin film material, which specifically comprises the following steps:

[0051] S1. ε-Caprolactone is added to a reactor, glycerol and stannous octanoate are added, and the mass ratio of ε-caprolactone, glycerol and stannous octanoate is 30:0.8:1.2. React at 130 °C for 6 h under argon protection, cool to room temperature, wash with 95 wt% ethanol, and dry to obtain a star initiator;

[0052] S2. L-Lactide is added to the reactor, then the star initiator obtained in S1 and stannous octanoate are added, and the mass ratio of L-lactide, star initiator and stannous octanoate is 20:2.2:0.12. React at 130 °C for 36 h under argon protection, cool to room temperature, wash with 95 wt% ethanol, and dry to obtain a copolymer;

[0053] S3. Dissolve the copolymer obtained in S2 in chloroform at an addition amount of 0.021 g / mL, then add the metal-polyphenol network-coated fiber crystals, mix evenly and pour into a polystyrene dish, and dry under vacuum to obtain the polymer breathable film material.

[0054] Example 3

[0055] A polymer breathable film material comprises the following components in parts by weight: 3 parts of ε-caprolactone, 29 parts of L-lactide, and 0.8 part of metal-polyphenol network-coated fiber crystals.

[0056] The preparation method of the metal-polyphenol network-coated fiber crystals comprises the following steps:

[0057] (1) Add microcrystalline cellulose to 65 wt% sulfuric acid solution at an addition amount of 0.1 g / mL, stir in a water bath at 50 °C for 2 h, then add 5 times the volume of distilled water to stop acid hydrolysis, centrifuge at 11500 rpm for 10 min to collect the precipitate, and prepare it into a 0.1 wt% suspension with deionized water, dialyze with deionized water until the pH is neutral, and rotary evaporate at 50 °C to obtain a 0.4 wt% nano-microcrystalline cellulose suspension;

[0058] (2) Mix 3-aminopropyltriethoxysilane and 80 wt% ethanol evenly at a volume ratio of 1:0.55 to obtain a modifier, then mix the 0.4 wt% nano-microcrystalline cellulose suspension obtained in step (1) with the modifier evenly at a volume ratio of 1:0.35, stir magnetically at 50 rpm for 2 h, adjust the pH to 3 with acetic acid, centrifuge at 11500 rpm for 10 min to collect the precipitate, wash with 95 wt% ethanol, and dry to obtain modified nano-microcrystalline cellulose;

[0059] (3) Prepare the modified nano-microcrystalline cellulose obtained in step (2) into a 0.1 wt% modified nano-microcrystalline cellulose suspension, add zinc chloride at an addition amount of 0.13 mmol / L, mix evenly, then add procyanidins in twice the molar amount of zinc chloride to obtain a mixed solution, then add a 3-morpholinopropanesulfonic acid buffer solution with the same volume as the mixed solution and a pH of 8, shake and react at 800 rpm for 1.2 h, centrifuge at 11000 rpm for 10 min to collect the precipitate, filter, and wash with deionized water to obtain the metal-polyphenol network-coated fiber crystals.

[0060] The present invention also provides a preparation method of a polymer breathable film material, which specifically comprises the following steps:

[0061] S1. Add ε-caprolactone to a reactor, add glycerol and stannous octoate, the mass ratio of ε-caprolactone, glycerol and stannous octoate is 30:0.7:1.1, heat and react at 125 °C for 5.5 h under argon protection, cool to room temperature, wash with 95 wt% ethanol and dry to obtain a star initiator;

[0062] S2. Add L-lactide into the reactor, and then add the star initiator obtained in S1 and stannous octoate. The mass ratio of L-lactide, star initiator and stannous octoate is 20:2.1:0.11. Heat and react at 125 °C for 33 h under argon protection, cool to room temperature, wash with 95 wt% ethanol, and dry to obtain the copolymer;

[0063] S3. Dissolve the copolymer obtained in S2 in chloroform at an addition amount of 0.02 g / mL, then add the metal-polyphenol network-coated fiber crystals, mix evenly and pour into a polystyrene dish, and dry under vacuum to obtain the polymer breathable film material.

[0064] Comparative Example 1

[0065] This comparative example provides a film material, which is different from Example 1 only in that the star initiator is not prepared in the components, and the other components and component contents are the same as those in Example 1.

[0066] Comparative Example 2

[0067] This comparative example provides a film material, which is different from Example 1 only in that the metal-polyphenol network-coated fiber crystals are not included in the components, and the other components and component contents are the same as those in Example 1.

[0068] Comparative Example 3

[0069] This comparative example provides a film material, which is different from Example 1 only in that 3-aminopropyltriethoxysilane is not included in the components, and the other components and component contents are the same as those in Example 1.

[0070] Experimental Example

[0071] 1. Air permeability test

[0072] Prepare the test samples of Examples 1-3 and Comparative Example 1 with a thickness of 0.8 mm, measure the air permeability of the samples with a differential pressure method gas permeation instrument, the test temperature is 20 °C, the area is Φ97 mm, and record the carbon dioxide permeability and oxygen permeability of the samples.

[0073] Figure 1 It is the result diagram of the air permeability test of Examples 1-3 and Comparative Example 1 of the present invention. As shown in the figure, the carbon dioxide permeabilities (cm 3 ·m·m −2 ·h −1 ·Pa −1 ) of Examples 1-3 and Comparative Example 1 are 8.9, 8.8, 8.9, and 6.3 respectively, and the oxygen permeabilities (cm 3 ·m·m −2 ·h −1 ·Pa −1)(They are) 1.3, 1.3, 1.3, and 0.9 respectively; the carbon dioxide permeability and oxygen permeability of Examples 1-3 are significantly higher than those of Comparative Example 1, indicating that the preparation and use of the star initiator improve the gas permeability of the thin film material.

[0074] 2. Mechanical property test

[0075] Specimens of Examples 1-3 and Comparative Example 2 were prepared into specimens with a length of 50 mm and a width of 10 mm, and a tensile test was carried out with an intelligent electronic tensile testing machine at a tensile speed of 6 mm / min, and the tensile strength and elongation at break of the samples were recorded.

[0076] Figure 2 This is the result graph of the mechanical property test of Examples 1-3 of the present invention and Comparative Example 2. As shown in the figure, the tensile strengths of Examples 1-3 and Comparative Example 1 are 37.4 MPa, 38.6 MPa, 36.5 MPa, and 28.3 MPa respectively, and the elongations at break are 286.6%, 287.1%, 283.9%, and 203.5% respectively; the tensile strength and elongation at break of Examples 1-3 are significantly higher than those of Comparative Example 2, indicating that the preparation and use of the metal-polyphenol network-coated fiber crystals improve the mechanical properties of the thin film material.

[0077] 3. Antibacterial property test

[0078] Take 1 mL each of Escherichia coli and Salmonella liquid with a concentration of 1.2×10 8 CFU / mL and inoculate them into 100 mL of liquid medium. 0.2 g of the materials obtained from Examples 1-3 and Comparative Examples 2-3 were added to the experimental groups respectively, and nothing was added to the control group. Under natural light, the mixture was cultured with constant shaking for 10 h, the total number of colonies was measured, and the antibacterial rate was calculated:

[0079] Antibacterial rate = (number of colonies in the control group - number of colonies in the experimental group) / number of colonies in the control group × 100%.

[0080] Figure 3 This is the result graph of the antibacterial property test of Examples 1-3 of the present invention and Comparative Examples 2-3. As shown in the figure, the antibacterial rates of Escherichia coli of Examples 1-3 and Comparative Example 1 are 99.6%, 99.8%, 99.3%, 2.3%, and 83.6% respectively, and the antibacterial rates of Salmonella are 99.9%, 99.8%, 99.6%, 1.9%, and 86.1% respectively; the antibacterial rates of Escherichia coli and Salmonella of Examples 1-3 are significantly higher than those of Comparative Examples 2-3, indicating that the preparation and use of the metal-polyphenol network-coated fiber crystals and the use of 3-aminopropyltriethoxysilane improve the antibacterial properties of the thin film material.

[0081] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention.

[0082] The above describes the present invention and its embodiments. Such description is not restrictive. What is shown in the drawings is only one of the embodiments of the present invention, and the actual application is not limited thereto. In general, if those of ordinary skill in the art are inspired by it and, without departing from the gist of the present invention, design similar methods and embodiments to this technical solution without creative efforts, they should all fall within the protection scope of the present invention.

Claims

1. A polymer breathable film material, characterized in that: It comprises the following components in parts by weight: 2.6 - 3.1 parts of ε-caprolactone, 27 - 30 parts of L-lactide, and 0.6 - 0.9 part of metal-polyphenol network-coated fiber crystals; The preparation method of the metal-polyphenol network-coated fiber crystals comprises the following steps: (1) Add microcrystalline cellulose into 65 wt% sulfuric acid solution at an addition amount of 0.09 - 0.11 g / mL, stir in a water bath, then add 5 times the volume of distilled water to stop acidolysis, centrifuge to obtain the precipitate, and prepare it into a 0.1 wt% suspension with deionized water, dialyze with deionized water until the pH is neutral, and rotary evaporate at 50 °C to obtain a 0.4 wt% nano-microcrystalline cellulose suspension; (2) Mix 3-aminopropyltriethoxysilane and 80 wt% ethanol evenly to obtain a modifier, then mix the 0.4 wt% nano-microcrystalline cellulose suspension obtained in step (1) with the modifier evenly, stir magnetically at 50 rpm for 2 h, adjust the pH to 3 with acetic acid, centrifuge to obtain the precipitate, wash with 95 wt% ethanol, and dry to obtain modified nano-microcrystalline cellulose; (3) Prepare the modified nano-microcrystalline cellulose obtained in step (2) into a 0.1 wt% modified nano-microcrystalline cellulose suspension, add zinc chloride, mix evenly, then add procyanidin with twice the molar amount of zinc chloride to obtain a mixed solution, then add a 3-morpholinopropanesulfonic acid buffer solution with a pH of 8 and an equal volume to the mixed solution, oscillate and react at 800 rpm for 1 - 1.5 h, centrifuge at 11000 rpm for 10 min to obtain the precipitate, filter, and wash with deionized water to obtain metal-polyphenol network-coated fiber crystals; The preparation method of the high molecular breathable thin film material comprises the following steps: S1. Add ε-caprolactone into a reactor, add glycerol and stannous octoate, heat and react under argon protection, cool to room temperature, wash with 95 wt% ethanol, and dry to obtain a star initiator; S2. Add L-lactide into a reactor, then add the star initiator obtained in S1 and stannous octoate, heat and react under argon protection, cool to room temperature, wash with 95 wt% ethanol, and dry to obtain a copolymer; S3. Dissolve the copolymer obtained in S2 in chloroform, then add metal-polyphenol network-coated fiber crystals, mix evenly, pour into a polystyrene dish, and dry in vacuum to obtain a high molecular breathable thin film material.

2. The polymer breathable thin film material according to claim 1, wherein: In step (1), the water bath stirring temperature is 45 - 55 °C, and the time is 1.5 - 2.5 h; the centrifugation speed is 11000 - 12000 rpm, and the time is 8 - 12 min.

3. The polymer breathable film material according to claim 2, characterized in that: In step (2), the volume ratio of 3-aminopropyltriethoxysilane to 80 wt% ethanol is 1:0.5 - 0.6; the volume ratio of the 0.4 wt% nano-microcrystalline cellulose suspension obtained in step (1) to the modifier is 1:0.3 - 0.4; the centrifugation speed is 11000 - 12000 rpm, and the time is 8 - 12 min.

4. The polymer breathable film material according to claim 3, characterized in that: In step (3), the addition amount of zinc chloride is 0.12 - 0.14 mmol / L.

5. The polymer breathable film material according to claim 4, wherein: In S1, the mass ratio of ε-caprolactone, glycerol and stannous octoate is 30:0.6 - 0.8:1 - 1.2; the heating reaction temperature is 120 - 130 °C, and the time is 5 - 6 h.

6. The polymer breathable film material according to claim 5, wherein: In S2, the mass ratio of L-lactide, star initiator and stannous octoate is 20:2 - 2.2:0.1 - 0.12, the heating reaction temperature is 120 - 130 °C, and the time is 30 - 36 h.

7. The polymer breathable film material according to claim 6, characterized in that: In S3, the addition amount of the copolymer obtained in S2 in chloroform is 0.019 - 0.021 g / mL.

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