Biodegradable packaging film bag for medical fabric and preparation method of biodegradable packaging film bag

Abstract

The invention relates to the technical field of biodegradable high polymer materials, in particular to a biodegradable packaging film bag for medical fabric and a preparation method of the biodegradable packaging film bag. The problem that the biodegradation characteristic and the mechanical property of a traditional packaging film bag cannot be considered at the same time is solved. The preparation method comprises the following steps: acetylating corn starch, and further grafting and modifying by combining oleoyl chloride to obtain a modified starch matrix; carrying out sulfuric acid hydrolysis and amination treatment on the nanocrystal cellulose to obtain aminated nanocrystal cellulose; the preparation method comprises the following steps: blending chitosan with an acetic acid solution, epsilon-caprolactone and a catalyst, and carrying out ultrasonic treatment to obtain a synergistic antibacterial compatibilizer; and the biodegradable packaging film bag for the medical fabric is finally obtained by carrying out melt ultrasonic treatment on the three components at the same time and combining synchronous two-way stretching, blow molding, corona and heat setting treatment, rolling and heat sealing.

Description

Technical Field

[0001] The present invention relates to the technical field of biodegradable polymer materials, and particularly to a biodegradable packaging film bag for medical fabrics and a preparation method thereof. Background Art

[0002] The environmental problems caused by traditional plastic packaging in the medical industry have been increasingly concerned. Traditional packaging film bags mostly use petroleum-based plastics (such as polyethylene, polypropylene, polyvinyl chloride, and polyethylene terephthalate, etc.), which do not degrade easily, resulting in a large amount of landfill and microplastic pollution, which has raised concerns about their long-term environmental impact. For example, reports have pointed out that the degradation of thin films or soft plastic bags may take 10 - 20 years, while harder plastics require 500 - 1000 years. To address this challenge, the concept of biodegradable packaging has emerged, aiming to reduce the environmental impact of packaging film bags through natural decomposition. Market forecasts show that the global biodegradable medical packaging market is growing significantly, which reflects the increasing demand for environmentally friendly alternatives.

[0003] For medical fabric packaging, biodegradability (decomposing within a reasonable time without producing harmful residues) and mechanical properties (strength, puncture resistance, and sealing performance) are both crucial requirements. However, there are inherent challenges in achieving a balance between the two. Generally, materials with good biodegradability tend to have weak mechanical properties, and vice versa. Medical fabric packaging has strict requirements for specific mechanical properties. For example, sufficient tensile strength is required to withstand the stress during handling and transportation, sufficient puncture resistance is required to protect the fabric from damage by sharp medical devices, and reliable sealing performance is required to maintain the sterility of the internal fabric. Research has shown that the basic chemical and structural characteristics that promote biodegradation tend to weaken the strength and durability of materials. Therefore, developing materials that can meet the strict mechanical property requirements of medical packaging and can be effectively biodegradable after use is the main challenge in this field currently.

[0004] Therefore, a biodegradable packaging film bag for medical fabrics and a preparation method thereof are proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a biodegradable packaging film bag for medical fabrics and a preparation method thereof. The modified starch matrix is obtained by acetylating corn starch and further graft-modifying it with oleoyl chloride; the aminated nanocrystalline cellulose is obtained by sulfuric acid hydrolysis and amination treatment of nanocrystalline cellulose; the synergistic antibacterial compatibilizer is obtained by blending chitosan with acetic acid solution, ε-caprolactone, and a catalyst and ultrasonic treatment; the three are simultaneously subjected to melt ultrasonic treatment, combined with synchronous biaxial stretching, blow molding, corona treatment, and heat setting treatment, and then wound and heat-sealed to obtain the final biodegradable packaging film bag for medical fabrics.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] On the one hand, the present invention provides a preparation method of a biodegradable packaging film bag for medical fabrics. The preparation method of the packaging film bag is as follows:

[0008] Add a sodium hydroxide solution and acetic anhydride to the starch emulsion, and then add a hydrochloric acid solution to adjust the pH value to obtain acetic starch;

[0009] Graft-modify the acetic starch with oleoyl chloride to obtain modified starch;

[0010] Prepare a nanocrystalline cellulose aqueous dispersion by the H2SO4 hydrolysis method;

[0011] Perform surface amination treatment on the nanocrystalline cellulose aqueous dispersion to obtain aminated nanocrystalline cellulose;

[0012] Dissolve chitosan with a molecular weight of 0.5 - 1.0 kDa in acetic acid solution, add ε-caprolactone and a catalyst and mix to obtain a blend;

[0013] Ultrasonically disperse, precipitate, centrifuge and wash the blend to neutrality, and dry to obtain a synergistic antibacterial compatibilizer;

[0014] Melt-ultrasonic the modified starch, aminated nanocrystalline cellulose and synergistic antibacterial compatibilizer to obtain a melt tube blank;

[0015] Simultaneously biaxially stretch and blow-mold the melt tube blank to obtain a packaging film;

[0016] Corona, heat-set and heat-seal the packaging film to obtain a packaging film bag.

[0017] Preferably, the preparation method of the modified starch is as follows: Add 120 - 130 parts of acetic starch and anhydrous dimethyl sulfoxide to a reaction flask, stir at 90 °C for 3 h under nitrogen protection; add anhydrous pyridine, and dropwise add 40 - 45 parts of oleoyl chloride at a rate of 0.5 - 0.8 parts / min through a constant pressure dropping funnel; react for 6 h under nitrogen protection to obtain a mixture; pour the mixture into anhydrous ethanol, filter, wash with water and dry to obtain the modified starch.

[0018] Preferably, the preparation method of the acetic starch is as follows: Disperse dry corn starch in distilled water to form a starch emulsion; add a 3 - 5 wt% sodium hydroxide solution while stirring, and maintain the pH value of the system at 8.5 - 9.0; stir and dropwise add acetic anhydride at 30 - 35 °C, and simultaneously dropwise add the sodium hydroxide solution, and maintain the pH value of the reaction system at 8.5 - 9.0; neutralize the pH value of the system to 7.0 with a 1 M hydrochloric acid solution, filter, wash and dry to obtain the acetic starch.

[0019] Preferably, the preparation method of the aminated nanocrystalline cellulose is as follows: Add 5 wt% of the nanocrystalline cellulose aqueous dispersion and disperse it in anhydrous ethanol to obtain a mixed dispersion; Add 0.5 - 1.0 parts of (3-aminopropyl)triethoxysilane to the mixed dispersion, stir at room temperature for 1.0 h, and stir and react at 75 °C for 4 h to obtain a reaction mixture; Centrifuge the reaction mixture for 15 - 20 min, wash and disperse the precipitate; Dry to obtain the aminated nanocrystalline cellulose.

[0020] Preferably, the preparation method of the nanocrystalline cellulose aqueous dispersion is as follows: Immerse cotton fibers in a sodium hydroxide solution at 80 °C for 2 h, wash with water until neutral to obtain pretreated cellulose; Add a 63 - 68 wt% H2SO4 solution and the pretreated cellulose to a reaction flask, stir and react at 45 - 50 °C for 60 - 90 min; Add distilled water to quench the reaction; Centrifuge at a rotation speed of 8000 - 10000 rpm; Repeat centrifugation 3 times, and purify by dialysis (select a cellulose membrane with a molecular weight cut-off of 12 - 14 kDa for the dialysis bag, the dialysis time is 48 h, and replace the distilled water every 8 h) until the pH value of the dialysis solution is between 6.5 - 7.0 to obtain a nanocrystalline cellulose suspension; Concentrate and retain the precipitate, and add distilled water to prepare a 5 wt% nanocrystalline cellulose aqueous dispersion.

[0021] Preferably, the preparation method of the synergistic antibacterial compatibilizer is as follows: Dissolve chitosan with a molecular weight of 0.5 - 1.0 kDa in a 1 - 3 wt% acetic acid solution, stir until completely dissolved; Add ε-caprolactone and 0.016 - 0.020 parts of stannous octoate catalyst and react under nitrogen protection for 4 - 8 h to obtain a blend; Keep the blend at an ultrasonic frequency of 20 - 40 kHz for 3 min; Precipitate, centrifuge and wash until neutral, and dry to obtain the synergistic antibacterial compatibilizer; The molar ratio of chitosan to ε-caprolactone is 1.0:1.0 - 1.5.

[0022] Preferably, the preparation method of the packaging film bag is as follows: Corona-treat the packaging film in a nitrogen atmosphere at a power of 120 - 150 W for 5 s; Then, perform heat setting treatment at 80 - 100 °C for 10 min and wind up with a tension of 50 - 100 N to obtain a packaging film with a thickness of 90 - 115 μm; Heat-seal at a pressure of 0.6 MPa and a temperature of 180 °C for 3 - 6 s to obtain the packaging film bag.

[0023] Preferably, the preparation method of the packaging film is as follows: Cool the melt tube blank to 55 °C, perform synchronous biaxial stretching at a stretching speed of 10 - 15 m / min, the longitudinal stretching ratio is 2.5 times, and the transverse stretching ratio is 3.5 times; Subsequently, blow up under a blow molding pressure of 0.8 - 1.2 MPa to obtain the packaging film.

[0024] Preferably, the preparation method of the melt tube is as follows: 100 parts of modified starch, 5-10 parts of amino-modified nanocrystalline cellulose and 10-15 parts of synergistic antibacterial bulking agent are fed into a twin-screw extruder with an ultrasonic generator; the melt section temperature is 160-180°C and the ultrasonic frequency is 25-30kHz to react to obtain a melt tube.

[0025] Another aspect of the present invention provides a biodegradable packaging film bag for medical fabrics. The raw materials for preparing the biodegradable packaging film bag include modified starch, amino-modified nanocrystalline cellulose and a synergistic antibacterial bulking agent. The biodegradable packaging film bag is prepared by any of the above preparation methods.

[0026] Unless otherwise specified, all “parts” mentioned in the present invention are “parts by mass”; and all “part ratios” mentioned in the present invention are “part ratios by mass”.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. By adjusting parameters such as the alkali concentration, pH, and temperature of the acetylation reaction, as well as the relative amount and addition rate of oleoyl chloride in the oleylation reaction, the chemical structure of the modified starch was optimized and regulated. The introduction of acetyl groups replaced some of the hydroxyl groups in corn starch. Their steric hindrance and relatively weak polarity significantly disrupted the hydrogen bond network of corn starch, thereby reducing the regularity of the starch chains, lowering its crystallinity and gelatinization temperature, and improving the solubility and dispersion of acetic acid starch in dimethyl sulfoxide. The long and flexible oleoyl side chains further disrupted the regular arrangement and residual hydrogen bonds between the acetic acid starch molecular chains. The resulting long-chain fatty acid ester bonds were highly sensitive to esterases and easily hydrolyzed and cut by esterases secreted by microorganisms in a composting environment. At the same time, they complemented the enzymatic hydrolysis of the glycosidic bonds in the modified starch backbone, accelerating the breakage and disintegration of the packaging film bags in multiple ways, thereby improving their biodegradability.

[0029] 2. By precisely controlling the conditions of sulfuric acid hydrolysis, nanocrystalline cellulose with high crystallinity and suitable aspect ratio is obtained, and through effective purification (centrifugation and dialysis), it is ensured that its surface carries sulfate groups, thereby achieving stable dispersion in the aqueous system, laying the foundation for subsequent uniform surface modification; (3-aminopropyl) triethoxysilane is then used to chemically functionalize the surface of the nanocrystalline cellulose, introducing amino active sites through covalent bonds, and strict centrifugation purification steps are used to remove impurities that interfere with interfacial binding; finally, the amino groups on the surface of the aminated nanocrystalline cellulose are used to form strong hydrogen bond interactions with the modified starch matrix and the synergistic antibacterial compatibilizer, thereby enhancing the overall tear resistance of the packaging film bag.

[0030] 3. By controlling the molecular weight of chitosan, the molar ratio of chitosan to ε-caprolactone, and the dosage of stannous octoate catalyst in combination with ultrasonic action, the chitosan backbone endows the synergistic compatibilizing antibacterial agent with antibacterial and biodegradable properties, and the polycaprolactone graft chain endows it with compatibility with the hydrophobic microdomains in the matrix. Finally, a synergistic antibacterial compatibilizer with a clear amphiphilic structure and the ability to effectively reduce the interfacial tension is prepared. Through the synergistic effect of component ratio optimization and melt ultrasonic treatment, the uniform dispersion and anchoring mechanism of amino-functionalized nanocrystalline cellulose in the modified starch matrix are realized, forming a melt tube blank with high interfacial strength and low defect density, further improving the biodegradable and mechanical properties of the packaging film bag.

[0031] 4. Adopt a process that combines synchronous biaxial stretching with appropriate blow molding pressure to induce regular biaxial orientation of polymer molecular chains, forming a packaging film with high mechanical strength and toughness; corona treat the packaging film under a nitrogen atmosphere to effectively excite the plasma to chemically modify the surface of the packaging film, introducing polar groups and significantly increasing its surface energy; then perform heat setting treatment to relax the stretched and oriented molecular chain segments, releasing most of the internal stress. This process prompts the molecular chains to adjust to a more stable arrangement state microscopically while maintaining the macroscopic orientation, undergoing secondary crystallization and improving the crystal region structure; a packaging film bag with high surface energy, low internal stress, and high dimensional stability is obtained, providing a reliability guarantee for the application of the packaging film bag to medical textiles. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a test effect diagram of the biodegradable and mechanical properties of Examples 13 - 18 and Comparative Examples 11 - 17 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying 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 creative efforts shall fall within the protection scope of the present invention.

[0034] Please refer to Figure 1 , the present invention provides a biodegradable packaging film bag for medical textiles and its preparation method, and the technical solutions are as follows:

[0035] Example 1

[0036] Take 100 parts of corn starch and dry it to a constant weight in an oven at 100 °C; in a reaction flask equipped with a stirrer, thermometer and pH meter, disperse 100 parts of the dried corn starch in 400 parts of distilled water to form a uniform starch emulsion; at room temperature, while stirring, add a 3 wt% sodium hydroxide solution to adjust and maintain the pH value of the system at 8.5; stir and dropwise add 75 parts of acetic anhydride at 35 °C, and the dropping time is 1 h; monitor the pH value of the reaction system during the dropping of acetic anhydride, and simultaneously dropwise add sodium hydroxide solution to keep the pH value of the reaction system at 8.5; after the dropping is completed, stir and react for 2 h, use 1 M hydrochloric acid solution to neutralize the pH value of the system to 7.0, filter, wash and dry to obtain acetylated starch.

[0037] Add 130 parts of acetylated starch and 800 parts of anhydrous dimethyl sulfoxide to a dry reaction flask equipped with a stirrer, thermometer, condenser and nitrogen protection device. Under nitrogen protection, heat to 90 °C and continuously stir for 3 h; add 25 parts of anhydrous pyridine, and dropwise add 41 parts of oleoyl chloride at a rate of 0.6 parts / min through a constant pressure dropping funnel; after the dropping is completed, react for 6 h under nitrogen protection to obtain a mixture; stop heating, cool to room temperature, and pour the mixture into 8000 parts of anhydrous ethanol at a rotation speed of 800 rpm, filter, wash with water and dry to obtain modified starch.

[0038] Take 10 parts of cotton fibers and soak them in a 2 wt% sodium hydroxide solution at 80 °C for 2 h, wash with water until neutral to obtain pretreated cellulose; add 100 parts of a 63 wt% H2SO4 solution to the reaction flask, add 10 parts of pretreated cellulose, and stir and react at 45 °C for 90 min; after the reaction is completed, add distilled water to quench the reaction; centrifuge at 8000 rpm for 10 min; repeat centrifugation 3 times, and dialyze and purify (select a cellulose membrane with a molecular weight cut-off of 12 - 14 kDa for the dialysis bag, the dialysis time is 48 h, and replace the distilled water every 8 h) until the pH of the dialysis solution is stable at 7.0 to obtain a nanocrystalline cellulose suspension; concentrate and retain the precipitate, and add distilled water to prepare a 5 wt% aqueous dispersion of nanocrystalline cellulose.

[0039] Add 200 parts of a 5 wt% aqueous dispersion of nanocrystalline cellulose and 800 parts of anhydrous ethanol (95 wt%) to the reaction flask, stir and mix to obtain a mixed dispersion; add 0.8 parts of (3-aminopropyl)triethoxysilane to the mixed dispersion, stir at room temperature for 0.8 h and then heat to 75 °C, stir and react for 4 h to obtain a reaction mixture; centrifuge the reaction mixture at 10000 rpm for 15 min, remove the supernatant, wash and disperse the precipitate; repeat the centrifugation-washing-dispersion process 5 times and then dry to obtain amino-functionalized nanocrystalline cellulose.

[0040] Dissolve 10 parts of chitosan with a molecular weight of 0.5 kDa in 40 parts of acetic acid solution with a concentration of 3 wt%, and stir until completely dissolved; add ε-caprolactone and 0.020 parts of stannous octoate catalyst, mix evenly, and react at 100 °C under nitrogen protection for 6 h to obtain a blend; keep the blend under ultrasonic conditions with a frequency of 30 kHz for 3 min; precipitate, centrifuge and wash until neutral, and dry to obtain a synergistic antibacterial compatibilizer; the molar ratio of chitosan to ε-caprolactone is 1.0:1.0.

[0041] Feed 100 parts of modified starch, 7 parts of amino-functionalized nanocrystalline cellulose and 10 parts of synergistic antibacterial compatibilizer into a twin-screw extruder equipped with an ultrasonic generating device, and the screw speed is 200 rpm; the temperature of the feeding section is 140 °C, and the temperature of the melting section is 160 °C; react under ultrasonic conditions with a frequency of 30 kHz, a power of 1.2 kW, and an ultrasonic temperature of 180 °C for 3 min to obtain a melt tube blank.

[0042] Cool the melt tube blank to 55 °C, and perform synchronous biaxial stretching at a stretching speed of 10 m / min, with a longitudinal stretching ratio of 2.5 times and a transverse stretching ratio of 3.5 times; then, blow up for 5 s under a blow molding pressure of 1.2 MPa to obtain a packaging film.

[0043] Corona treat the packaging film for 5 s in a nitrogen atmosphere with a power of 120 W; then perform heat setting treatment at 100 °C for 10 min and wind up with a tension of 80 N to obtain a packaging film with a thickness of 110 μm; heat seal for 6 s at a pressure of 0.6 MPa and a temperature of 180 °C to obtain a packaging film bag.

[0044] Example 2 - 6

[0045] Refer to the preparation method and parameter conditions of Example 1, and the specific differences are shown in Table 1.

[0046] Comparative Example 1

[0047] Refer to the preparation method and parameter conditions of Example 6, except that acetic acid starch is replaced with ordinary corn starch.

[0048] Comparative Example 2

[0049] Refer to the preparation method and parameter conditions of Example 6, except that in the process of preparing modified starch, instead of using a constant-pressure dropping funnel to drop oleoyl chloride, all oleoyl chloride is directly added.

[0050] Comparative Example 3

[0051] Refer to the preparation method and parameter conditions of Example 6, except that in the process of preparing acetic acid starch, 0.3 wt% sodium hydroxide solution is added to the starch emulsion.

[0052] Comparative Example 4

[0053] Referring to the preparation method and parameter conditions of Example 6, the difference is that during the preparation of starch acetate, 20 wt% sodium hydroxide solution was added to the starch emulsion.

[0054] Comparative Example 5

[0055] Referring to the preparation method and parameter conditions of Example 6, the difference is that during the preparation of starch acetate, the step of neutralizing the pH value of the system to 7.0 with 1M hydrochloric acid solution was omitted, and the starch acetate was directly filtered, washed and dried.

[0056] Experimental Example 1 Biodegradability Test

[0057] Disintegration rate under composting conditions: Determined according to the standard of GB / T 19811-2005. The test sample was cut into a size of 10 cm × 10 cm, and the test sample was loaded into a compost reactor (initial moisture content was 50%). After 12 weeks of composting test, it was screened using a sieve with a pore size of 2.0 mm. The mass (dry weight) of the test sample filtered through the sieve was m1, and the mass (dry weight) of the test sample remaining on the sieve was m2. The calculation formula for the disintegration rate is: The specific test results are shown in Table 1.

[0058] Table 1 Biodegradability Test of Examples 1-6 and Comparative Examples 1-5

[0059]

[0060] As shown in the data of Table 1, the disintegration rates of Examples 1-6 were all higher than 95.0%, which were significantly better than those of Comparative Examples 1-5. This shows that acetylating corn starch to obtain starch acetate and then modifying the starch acetate to prepare modified starch as a raw material can endow the prepared packaging film bags with good biodegradability. In Comparative Example 1, ordinary corn starch was used to replace starch acetate. For the unacetylated corn starch, there are a large number of strong hydrogen bond interactions in its molecular chain, which restricts the activity of the hydroxyl groups on the starch molecules by the hydrogen bond network, resulting in a significant decrease in its solubility and dispersibility in dimethyl sulfoxide solvent. The packaging film bags prepared with such raw materials retaining a large amount of starch are not conducive to the erosion and enzymatic hydrolysis of microorganisms. In Comparative Example 2, all oleoyl chloride was added at once, resulting in an instantaneously too high local concentration in the reaction system, triggering a violent reaction, intensifying side reactions and premature degradation of raw materials, seriously damaging the uniformity of the material structure, and thus reducing the disintegration rate.

[0061] In Comparative Example 3, during the acetylation reaction for preparing starch acetate, the concentration of the sodium hydroxide solution added was too low, unable to provide sufficient catalytic activity and effectively neutralize the acetic acid generated in the reaction, inhibiting the acetylation reaction, resulting in incomplete acetylation of the modified starch, poor biodegradability, and a decrease in the disintegration rate of the packaging film bags under composting conditions. In Comparative Example 4, using a high-concentration sodium hydroxide solution would significantly hydrolyze the starch glycosidic bond, causing the starch molecular chain to break and the molecular weight to decrease sharply; the acetylation reaction occurred on the severely degraded starch fragments, and the structure of the resulting starch acetate was severely damaged. Even if oleoylation was carried out again, it was impossible to form a polymer material with good mechanical properties and expected biodegradable characteristics. In Comparative Example 5, not using 1M hydrochloric acid solution to neutralize the pH value of the system would cause a large amount of sodium hydroxide to remain in the starch acetate. During subsequent drying, storage, and high-temperature extrusion processes, it would continuously reduce the acetylation degree of the modified starch, resulting in the starch acetate and the modified starch approaching the unmodified degree. The internal hydrogen bond interaction of the prepared packaging film bag material was enhanced, the structure was dense, hindering the action of microorganisms and hydrolases, thereby reducing its disintegration rate under composting conditions.

[0062] In summary, by adjusting parameters such as the alkali concentration, pH, and temperature of the acetylation reaction, as well as the relative dosage and dropping rate of oleoyl chloride in the oleoylation reaction, the optimization and regulation of the chemical structure of the modified starch were achieved; the introduction of acetyl groups replaced some hydroxyl groups in corn starch, and its steric hindrance and relatively weak polarity significantly damaged the hydrogen bond network of corn starch, thereby reducing the regularity of the starch chain, its crystallinity and gelatinization temperature, and improving the dissolution and dispersion of starch acetate in dimethyl sulfoxide; the long and flexible oleoyl side chains further disrupted the regular arrangement and residual hydrogen bonds between the starch acetate molecular chains. The generated long-chain fatty acid ester bonds were highly sensitive to esterase and were easily hydrolyzed and cleaved by the esterase secreted by microorganisms in the composting environment; at the same time, it complemented the enzymatic hydrolysis of the main chain glycosidic bond of the modified starch, accelerating the breakage and disintegration of the packaging film bags through multiple pathways and improving its biodegradability.

[0063] Examples 7 - 12

[0064] Referring to the preparation method and parameter conditions of Example 6, the specific differences are shown in Table 2; in Table 2, the centrifugation time is the centrifugation time of the reaction mixture; the stirring temperature and reaction time are the stirring temperature and reaction time after adding nanocrystalline cellulose during the preparation of the nanocrystalline cellulose aqueous dispersion; the centrifugation speed is the centrifugation speed after quenching the reaction by adding distilled water.

[0065] Comparative Example 6

[0066] Referring to the preparation method and parameter conditions of Example 12, the difference is that (3-aminopropyl)triethoxysilane is not added during the preparation of amino-functionalized nanocrystalline cellulose.

[0067] Comparative Example 7

[0068] Referring to the preparation method and parameter conditions of Example 12, except that the reaction mixture is not centrifugally dispersed during the preparation of amino-functionalized nanocrystalline cellulose.

[0069] Comparative Example 8

[0070] Referring to the preparation method and parameter conditions of Example 12, except that cotton fibers are replaced by wheat straw fibers during the preparation of the nanocrystalline cellulose aqueous dispersion.

[0071] Comparative Example 9

[0072] Referring to the preparation method and parameter conditions of Example 12, except that a nanocrystalline cellulose suspension is prepared by an enzymatic hydrolysis method.

[0073] Comparative Example 10

[0074] Referring to the preparation method and parameter conditions of Example 12, except that after adding distilled water to quench the reaction during the preparation of the nanocrystalline cellulose aqueous dispersion, centrifugation is not performed, and the nanocrystalline cellulose suspension is directly obtained by dialysis purification.

[0075] Experimental Example 2 Mechanical Property Test

[0076] Five parallel specimens with dimensions of 76 mm × 63 mm are cut, and the thickness of the specimens is 110 μm; a 20 mm ± 0.1 mm incision is precisely cut along the length direction in the middle of the specimens, and a tear strength test is performed using a tear tester; the tear strength calculation formula is: The results are averaged; the specific test results are shown in Table 2.

[0077] Table 2 Mechanical Property Tests of Examples 7 - 12 and Comparative Examples 6 - 10

[0078]

[0079] As shown in the data in Table 2, the tear strengths of Examples 7-12 are all greater than 110 mN / mm, significantly superior to those of Comparative Examples 6-10. This indicates that in Examples 7-12, a nanocrystalline cellulose aqueous dispersion with stable properties is obtained by the sulfuric acid hydrolysis method, and then (3-aminopropyl)triethoxysilane is used to conduct surface chemical functionalization on the nanocrystalline cellulose. The hydrogen bond interaction between the generated amino-functionalized nanocrystalline cellulose, the modified starch matrix, and the synergistic antibacterial compatibilizer significantly improves the overall mechanical properties (tear strength) of the packaging film bag. When adding (3-aminopropyl)triethoxysilane during the preparation of amino-functionalized nanocrystalline cellulose, the triethoxysilyl group in its structure undergoes hydrolysis in the ethanol system to generate reactive silanol groups. On the one hand, these silanol groups undergo dehydration condensation reactions with the hydroxyl groups on the surface of the nanocrystalline cellulose to form stable Si-O-C covalent bonds. On the other hand, self-condensation also occurs between the silanol groups to form a Si-O-Si network structure, which is further anchored on the surface of the nanocrystalline cellulose, enhancing the binding ability between the amino-functionalized nanocrystalline cellulose and the matrix interface, thereby improving the overall tear strength of the packaging film bag. In Comparative Example 6, without adding (3-aminopropyl)triethoxysilane, the mainly exposed groups on the surface of the non-amino-functionalized nanocrystalline cellulose are hydroxyl groups. The hydrogen bond interaction formed by these hydroxyl groups and the groups in the modified starch matrix is much lower than that between the amino-functionalized nanocrystalline cellulose and the matrix, resulting in a decrease in the overall tear strength of the generated packaging film bag.

[0080] In Comparative Example 7, during the preparation of amino-functionalized nanocrystalline cellulose, the reaction mixture is not centrifugally dispersed, resulting in unremoved free (3-aminopropyl)triethoxysilane or its self-condensed reactive groups existing in the matrix in a non-bonded state. These impurities form independent and non-combined phases in the matrix, generating defective microstructures during subsequent processing, and thus leading to a decrease in the tear strength of the packaging film bag. In Comparative Example 8, during the preparation of the nanocrystalline cellulose aqueous dispersion, cotton fibers are replaced with wheat straw fibers. Since wheat straw fibers contain a large amount of hemicellulose and lignin, and the cellulose content only accounts for 30% of its total amount, this results in a large amount of impurities still remaining in the nanocrystalline cellulose after preliminary alkali treatment, and the effective cellulose content is low, severely reducing the yield and purity of the nanocrystalline cellulose. The lower amino-functionalization efficiency and surface impurities lead to a weakening of the interfacial binding force between it and the modified starch matrix, significantly reducing the stress transfer efficiency of the packaging film bag, and its tear strength drops significantly.

[0081] In Comparative Example 9, nanocrystalline cellulose suspension was prepared by an enzymatic hydrolysis method. The enzymatically hydrolyzed nanocrystalline cellulose lacking surface charge had poor dispersibility in ethanol and was prone to agglomeration. Even when (3-aminopropyl)triethoxysilane was added subsequently, the reaction mainly occurred on the outer surface of the agglomerates, and the internal nanocrystalline cellulose could not effectively contact the reactants, resulting in low amidation efficiency and uneven distribution. Instead of enhancing the overall binding, these agglomerates became stress concentration points inside the material and were easily broken under external forces, causing a sharp decrease in the tear strength of the packaging film bag. In Comparative Example 10, during the preparation of the nanocrystalline cellulose aqueous dispersion, after adding distilled water to quench the reaction, centrifugation was not carried out, and the nanocrystalline cellulose suspension was directly obtained by dialysis purification; this meant that the dialysis process needed to handle a system with a large volume and high impurity concentration, greatly prolonging the purification time, increasing the operation complexity, and having low purification efficiency; the finally obtained nanocrystalline cellulose aqueous dispersion contained more impurities, which in turn affected the interfacial enhancement effect of the generated amidated nanocrystalline cellulose.

[0082] In summary, by precisely controlling the sulfuric acid hydrolysis conditions, nanocrystalline cellulose with high crystallinity and appropriate aspect ratio was obtained, and through effective purification (centrifugation, dialysis), it was ensured that its surface carried sulfate groups, so as to obtain stable dispersion in an aqueous system, laying a foundation for subsequent uniform surface modification; then (3-aminopropyl)triethoxysilane was used to carry out surface chemical functionalization of the nanocrystalline cellulose, introducing amino active sites through covalent bonds, and removing impurities interfering with interfacial binding through strict centrifugation purification steps; finally, strong hydrogen bond interactions were formed between the amino groups on the surface of the amidated nanocrystalline cellulose and the modified starch matrix and the synergistic antibacterial compatibilizer, enhancing the overall tear resistance of the packaging film bag.

[0083] Examples 13 - 18

[0084] Referring to the preparation method and parameter conditions of Example 12, the specific differences are shown in Table 3; in Table 3, chitosan refers to chitosan; ε-caprolactone refers to ε-caprolactone; the reaction time and ultrasonic frequency one are the reaction time and ultrasonic frequency of the blend; M 壳聚糖 :M ε-己内酯 represents the molar ratio of chitosan to ε-caprolactone; the ultrasonic frequency two is the ultrasonic frequency during the preparation of the melt tube blank.

[0085] Comparative Example 11

[0086] Referring to the preparation method and parameter conditions of Example 15, the difference is that the molecular weight of chitosan during the preparation of the synergistic antibacterial compatibilizer is 0.1 kDa.

[0087] Comparative Example 12

[0088] Referring to the preparation method and parameter conditions of Example 15, except that the molecular weight of chitosan is 5.0 kDa during the preparation of the synergistic antibacterial compatibilizer.

[0089] Comparative Example 13

[0090] Referring to the preparation method and parameter conditions of Example 15, except that the molar ratio of chitosan to ε-caprolactone is 1.0:0.5 during the preparation of the synergistic antibacterial compatibilizer.

[0091] Comparative Example 14

[0092] Referring to the preparation method and parameter conditions of Example 15, except that the molar ratio of chitosan to ε-caprolactone is 0.5:1.0 during the preparation of the synergistic antibacterial compatibilizer.

[0093] Comparative Example 15

[0094] Referring to the preparation method and parameter conditions of Example 15, except that stannous octoate catalyst is not added during the preparation of the synergistic antibacterial compatibilizer.

[0095] Comparative Example 16

[0096] Referring to the preparation method and parameter conditions of Example 15, except that amino-functionalized nanocrystalline cellulose is not added during the preparation of the melt tube blank.

[0097] Comparative Example 17

[0098] Referring to the preparation method and parameter conditions of Example 15, except that ultrasound is not performed during the melting of the melt tube blank.

[0099] Experimental Example 3 Testing of Biodegradability and Mechanical (Barrier) Properties

[0100] Final biodegradation rate under composting conditions: Measured according to the ISO 14855-1-2012 standard. The test specimens were cut into 10 cm × 10 cm sizes and incubated at a constant temperature for 3 months under controlled composting (simulating the high-temperature stage of composting: temperature 58 ± 2 °C, humidity 50%, sufficient oxygen), and a blank control group was set up; the CO2 concentration in the air passing through each reaction bottle of the test specimens and the blank control group was measured every 3 days, and the cumulative CO2 release was calculated; the formula for calculating the final biodegradation rate is:

[0101]

[0102] Barrier property: The test specimens were sterilized with ethylene oxide according to the ISO 11135 standard, and the water vapor permeability of the test specimens before sterilization and after sterilization was measured using a water vapor transmission rate tester; the formula for calculating the retention rate of water vapor permeability is: The specific test results are shown in Table 4 andFigure 1 as shown

[0103] Table 3 Preparation parameters of Examples 13 - 18 and Comparative Examples 11 - 17

[0104]

[0105] Table 4 Tests on biodegradation performance and mechanical (barrier) properties of Examples 13 - 18 and Comparative Examples 11 - 17

[0106] Number Final biodegradation rate / % Retention rate of water vapor permeability / % Example 13 94.3 91.2 Example 14 94.1 90.9 Example 15 95.8 92.3 Example 16 95.2 91.9 Example 17 94.9 91.6 Example 18 95.6 92.1 Comparative Example 11 85.7 79.8 Comparative Example 12 83.2 75.6 Comparative Example 13 79.8 72.3 Comparative Example 14 73.2 68.4 Comparative Example 15 65.6 57.6 Comparative Example 16 78.3 69.7 Comparative Example 17 87.5 85.3

[0107] As shown in Table 4 and Figure 1 the data, the final biodegradation rates of Examples 13 - 18 are all greater than 94.0%, and the retention rates of water vapor permeability are all greater than 90.5%. The biodegradation performance and mechanical properties are significantly better than those of Comparative Examples 11 - 17. This shows that by finely regulating the preparation parameters and methods of the synergistic antibacterial compatibilizer, the melt preform formed through the synergistic effect of component ratio optimization and melt ultrasonic treatment in Examples 13 - 18 effectively improves the biodegradation performance and mechanical properties of the packaging film bags. In Comparative Example 11, the molecular weight of chitosan is too low, resulting in a significant shortening of its chain length. When grafting ε - caprolactone to form a polycaprolactone (chitosan - g - polycaprolactone) compatibilizer, the too - short main chain of chitosan limits its effective entanglement and dispersion ability in the modified starch matrix. At the same time, the provided amino active sites are reduced, and the steric hindrance effect is weakened, unable to effectively bridge the interfaces between the modified starch and the polycaprolactone graft chain and the aminated nanocrystalline cellulose, resulting in a decrease in both the compatibilization effect and antibacterial activity of the synergistic antibacterial compatibilizer, and uneven dispersion of each component in the melt preform. Eventually, the structure of the packaging film bag is uneven, with a large number of micro - defects, resulting in an increase in the initial water vapor permeability and a significant decrease in the structural stability after sterilization and the retention rate of water vapor permeability. This phase - separated structure hinders the uniform and complete degradation of the whole substrate by microorganisms, leading to a decrease in the final biodegradation rate. In Comparative Example 12, the molecular weight of chitosan is too high, resulting in difficulties in mass transfer and heat transfer during the grafting reaction, weakening the ultrasonic effect, and low and uneven production of the synergistic antibacterial compatibilizer. In the melt blending stage, the viscosity of the synergistic antibacterial compatibilizer increases, and its fluidity is poor. It is difficult for the synergistic antibacterial compatibilizer in the melt preform to effectively migrate to the phase interface to play its antibacterial compatibilization role, ultimately resulting in a decline in the biodegradation performance and mechanical properties of the packaging film bag.

[0108] In Comparative Example 13, the molar ratio of chitosan to ε-caprolactone was 1.0:0.5; the amount of ε-caprolactone was insufficient, meaning that the number of polycaprolactone segments grafted onto each chitosan molecule was insufficient, resulting in too small a proportion of the hydrophobic part of the formed synergistic antibacterial compatibilizer to form an effective interaction with the hydrophobic microdomains in the modified starch matrix, and the compatibilization effect deteriorated; during the subsequent formation of the melt tube blank, the interfacial binding force was weak, and the final generated packaging film bag had poor compatibility and increased interfacial defects, resulting in easy penetration of water vapor, and poor interfacial stability after sterilization, and a decrease in the retention rate of the water vapor permeability; at the same time, the discontinuous phase structure would hinder the degradation of microorganisms, leading to a decrease in the final biodegradation rate. In Comparative Example 14, the molar ratio of chitosan to ε-caprolactone was 0.5:1.0; the amount of chitosan was relatively insufficient, resulting in a decrease in the total amount of the formed synergistic antibacterial compatibilizer, and there were not enough synergistic compatibilizing antibacterial agent molecules migrating to the interface to reduce the interfacial tension and improve the compatibility; at the same time, the excessive ε-caprolactone agglomerated under the action of the catalyst, further reducing the final biodegradation rate and the retention rate of the water vapor permeability of the synergistic compatibilizing antibacterial agent. Stannous octoate is an efficient catalyst for the ring-opening polymerization of ε-caprolactone. In Comparative Example 15, no stannous octoate catalyst was added, directly resulting in the generated synergistic antibacterial compatibilizer not having the synergistic effect of antibacterial and compatibilization; what was added to the melt tube blank was a simple mixture of chitosan and ε-caprolactone, which volatilized, degraded, and polymerized during the melting stage, and the generated melt tube blank had serious phase separation, ultimately resulting in a serious decrease in the final biodegradation rate and the retention rate of the water vapor permeability of the packaging film bag.

[0109] Aminated nanocrystalline cellulose, as a nanofiller, mainly functions to enhance the mechanical properties of the matrix and improve the barrier properties; its high specific surface area and surface amino functional groups can form hydrogen bond and other interactions with the modified starch and the synergistic antibacterial compatibilizer, thus constructing a complete cross-linked network; while in Comparative Example 16, no aminated nanocrystalline cellulose was added, and due to the lack of the physical barrier formed by the aminated nanocrystalline cellulose, the water vapor permeability would increase significantly, the overall structural strength would decrease, the barrier properties would be lost, and although the packaging film bag disintegrated in the degradation environment, the efficiency was low. In Comparative Example 17, no ultrasonic treatment was carried out during the melting process of the melt tube blank. Without the ultrasonic action and relying only on the mechanical shearing action of the twin-screw extruder, the nanofillers in the melt tube blank could not be completely and effectively dispersed, and the overall mixing effect would become worse, and the biodegradation performance and mechanical properties of the finally generated packaging film bag would also decrease.

[0110] In summary, by controlling the molecular weight of chitosan, the molar ratio of chitosan to ε-caprolactone, and the dosage of stannous octoate catalyst in combination with ultrasonic action, the chitosan skeleton endows the synergistic compatibilizing antibacterial agent with antibacterial and biodegradable properties, and the polycaprolactone graft chain endows it with compatibility with the hydrophobic microdomains in the matrix. Finally, a synergistic antibacterial compatibilizer with a clear amphiphilic structure and capable of effectively reducing the interfacial tension is prepared. Through the synergistic effect of component ratio optimization and melt ultrasonic treatment, the uniform dispersion and anchoring mechanism of amino-functionalized nanocrystalline cellulose in the modified starch matrix are realized, forming a melt billet with high interfacial strength and low defect density, further improving the biodegradable and mechanical properties of the packaging film bag.

[0111] Examples 19 - 24

[0112] Referring to the preparation method and parameter conditions of Example 15, the specific differences are shown in Table 5.

[0113] Comparative Example 18

[0114] Referring to the preparation method and parameter conditions of Example 24, the difference is that the corona power is 60W.

[0115] Comparative Example 19

[0116] Referring to the preparation method and parameter conditions of Example 24, the difference is that the corona power is 300W.

[0117] Comparative Example 20

[0118] Referring to the preparation method and parameter conditions of Example 24, the difference is that no heat setting treatment is carried out during the preparation of the packaging film bag.

[0119] Comparative Example 21

[0120] Referring to the preparation method and parameter conditions of Example 24, the difference is that the blow molding pressure is 0.1MPa during the preparation of the packaging film.

[0121] Comparative Example 22

[0122] Referring to the preparation method and parameter conditions of Example 24, the difference is that the blow molding pressure is 5.0MPa during the preparation of the packaging film.

[0123] Experimental Example 4 Mechanical Property Test

[0124] Heat Sealing Property Test: Cut a 120mm×15mm specimen; clamp the specimen in the upper and lower fixtures of the tensile testing machine to ensure that the specimen is vertical, set the test speed to 200mm / min; start the tensile testing machine and record the maximum tensile force F (unit: N, Newton) when the heat-sealed part breaks. The specimen width is denoted as W (15mm), and the heat sealing strength calculation formula is: The specific test results are shown in Table 5.

[0125] Table 5 Mechanical properties test of Examples 19-24 and Comparative Examples 18-22

[0126]

[0127] As shown in Table 4, the heat seal strengths of Examples 19-24 were all greater than 1.65 N / mm, and the mechanical properties of Examples 19-24 were significantly higher than those of Comparative Examples 18-22. This indicates that the packaging film bags prepared in Examples 19-24 exhibited excellent heat seal and mechanical properties through the interaction between the processes. The purpose of corona treatment is to oxidize the packaging film surface through the plasma generated by high-voltage discharge, introducing oxygen-containing polar groups, thereby increasing the polarity and surface energy of the packaging film surface. In Comparative Example 18, the corona power was 60 W, which was insufficient to produce a sufficient number and density of polar groups on the packaging film surface, resulting in an insufficient increase in the packaging film surface energy. During heat sealing, the intermolecular attraction between the two interfaces was weak, ultimately manifesting as a decrease in the heat seal strength of the packaging film bag. In Comparative Example 19, the corona power was 300 W. Excessive energy input would cause the polymer main chain in the packaging film to break, producing low-molecular-weight oxidized substances. This prevented the packaging film from forming a continuous, uniform, and strong packaging film bag even under heat sealing conditions, resulting in a decrease in its heat seal strength.

[0128] Comparative Example 20, without heat setting, retains its high internal stress and orientation after stretching. During heat sealing, it exhibits a strong tendency to deorient and shrink, severely interfering with the effective diffusion, penetration, and entanglement of molecular chains at the interface and hindering the formation of a stable, strong interface layer. Consequently, the heat seal strength of the packaging film without heat setting is significantly lower than that of the packaging film with heat setting. The blow molding pressure in Comparative Example 21 is too low, failing to provide sufficient driving force for full and uniform expansion of the tube blank. This results in insufficient stretch orientation of the melt tube blank, resulting in uneven thickness and insufficient strength of the resulting packaging film. The substrate near the seal is susceptible to damage when subjected to external forces, manifesting as low heat seal strength. The excessively high blow molding pressure in Comparative Example 22 causes the melt tube blank to experience excessive stress during inflation, resulting in microscopic defects and cracks before rapid cooling and setting. Even if an interfacial bond is formed during heat sealing, these inherent structural weaknesses act as stress concentration points when subjected to force, leading to premature seal failure.

[0129] In summary, by adopting the process of combining synchronous biaxial stretching with appropriate blow molding pressure, the polymer molecular chains are induced to produce regular biaxial orientation, forming a packaging film with high mechanical strength and toughness. The packaging film is corona treated under a nitrogen atmosphere, effectively exciting the plasma to chemically modify the surface of the packaging film and introducing polar groups, significantly increasing its surface energy. Subsequently, heat setting treatment is carried out, enabling the stretched and oriented molecular chain segments to relax and releasing most of the internal stress. This process prompts the molecular chains to adjust to a more stable arrangement state microscopically while maintaining the macroscopic orientation, undergoing secondary crystallization and improving the crystal region structure. A packaging film bag with high surface energy, low internal stress and high dimensional stability is obtained, providing a reliability guarantee for the application of the packaging film bag in medical textiles.

[0130] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a biodegradable packaging film bag for medical fabrics, characterized in that: The preparation method of the packaging film bag is as follows: Add a sodium hydroxide solution and acetic anhydride to the starch emulsion. After adjusting the pH value with a hydrochloric acid solution to obtain acetic starch, graft-modify the acetic starch with oleoyl chloride to obtain modified starch; Perform amination treatment on the nanocrystalline cellulose aqueous dispersion prepared by H2SO4 hydrolysis to obtain aminated nanocrystalline cellulose; Dissolve 0.5 - 1.0 kDa chitosan in an acetic acid solution, add ε-caprolactone and a catalyst, and after mixing, perform ultrasonic dispersion, precipitation, centrifugal washing until neutral, and dry to obtain a synergistic antibacterial compatibilizer; Melt and ultrasonically treat the modified starch, the aminated nanocrystalline cellulose, and the synergistic antibacterial compatibilizer to obtain a melt tube blank; After synchronously biaxially stretching and blow molding the melt tube blank into a film, perform corona treatment, heat setting, and heat sealing to obtain the packaging film bag.

2. The preparation method of a biodegradable packaging film bag for medical fabrics according to claim 1, wherein: The preparation method of the modified starch is as follows: Add 120 - 130 parts of the acetic starch and anhydrous dimethyl sulfoxide to a reaction flask, stir at 90 °C for 3 h under nitrogen protection; add anhydrous pyridine, and dropwise add 40 - 45 parts of the oleoyl chloride at a rate of 0.5 - 0.8 parts / min through a constant pressure dropping funnel; react for 6 h under nitrogen protection to obtain a mixture; pour the mixture into anhydrous ethanol, perform suction filtration, wash with water, and dry to obtain the modified starch.

3. The preparation method of a biodegradable packaging film bag for medical fabrics according to claim 1, characterized in that: The preparation method of the acetic starch is as follows: Disperse dry corn starch in distilled water to form a starch emulsion; add the sodium hydroxide solution with a concentration of 3 - 5 wt% while stirring, and maintain the pH value of the system at 8.5 - 9.0; stir and dropwise add the acetic anhydride at 30 - 35 °C, and simultaneously dropwise add the sodium hydroxide solution, and maintain the pH value of the reaction system at 8.5 - 9.0; neutralize the pH value of the system to 7.0 with 1 M hydrochloric acid solution, perform suction filtration, wash, and dry to obtain the acetic starch.

4. The preparation method of a biodegradable packaging film bag for medical fabrics according to claim 1, characterized in that: The preparation method of the aminated nanocrystalline cellulose is as follows: Add 5 wt% of the nanocrystalline cellulose aqueous dispersion to anhydrous ethanol to obtain a mixed dispersion; add 0.5 - 1.0 parts of (3-aminopropyl)triethoxysilane to the mixed dispersion, stir at room temperature for 1.0 h, and stir and react at 75 °C for 4 h to obtain a reaction mixture; centrifuge the reaction mixture for 15 - 20 min, wash and disperse the precipitate; dry to obtain the aminated nanocrystalline cellulose.

5. The preparation method of a biodegradable packaging film bag for medical fabrics according to claim 1, characterized in that: The preparation method of the nanocrystalline cellulose aqueous dispersion is as follows: Immerse cotton fibers in the sodium hydroxide solution at 80 °C for 2 h, wash with water until neutral to obtain pretreated cellulose; add a 63 - 68 wt% H2SO4 solution and the pretreated cellulose to a reaction flask, stir and react at 45 - 50 °C for 60 - 90 min; add distilled water to quench the reaction; centrifuge at a speed of 8000 - 10000 rpm; repeat centrifugation 3 times, and dialyze and purify until the pH value of the dialysate is between 6.5 - 7.0 to obtain a nanocrystalline cellulose suspension; concentrate and retain the precipitate, and add distilled water to prepare a 5 wt% nanocrystalline cellulose aqueous dispersion.

6. The preparation method of a biodegradable packaging film bag for medical fabrics according to claim 1, characterized in that: The preparation method of the synergistic antibacterial compatibilizer is as follows: dissolve the chitosan with a molecular weight of 0.5 - 1.0 kDa in the acetic acid solution with a concentration of 1 - 3 wt%, and stir until completely dissolved; add the ε-caprolactone and 0.016 - 0.020 parts of stannous octoate catalyst, and react for 4 - 8 h under nitrogen protection to obtain a blend; keep the blend under ultrasonic waves with a frequency of 20 - 40 kHz for 3 min; precipitate, centrifuge and wash until neutral, and dry to obtain the synergistic antibacterial compatibilizer; the molar ratio of the chitosan to the ε-caprolactone is 1.0:1.0 - 1.

5.

7. The preparation method of a biodegradable packaging film bag for medical fabrics according to claim 1, characterized in that: The preparation method of the packaging film bag is as follows: carry out the corona treatment on the packaging film under a nitrogen atmosphere with a power of 120 - 150 W; then carry out the heat setting treatment at 80 - 100 °C and wind up with a tension of 50 - 100 N to obtain the packaging film with a thickness of 90 - 115 μm; heat seal for 3 - 6 s to obtain the packaging film bag.

8. The preparation method of a biodegradable packaging film bag for medical fabrics according to claim 1, characterized in that: The preparation method of the packaging film is as follows: cool the melt tube blank, and carry out synchronous biaxial stretching at a stretching speed of 10 - 15 m / min; blow up under a blow molding pressure of 0.8 - 1.2 MPa to obtain the packaging film.

9. The preparation method of a biodegradable packaging film bag for medical fabrics according to claim 1, characterized in that: The preparation method of the melt tube blank is as follows: feed 100 parts of the modified starch, 5 - 10 parts of the aminated nanocrystalline cellulose and 10 - 15 parts of the synergistic antibacterial compatibilizer into a twin-screw extruder equipped with an ultrasonic generating device; react at a melting section temperature of 160 - 180 °C and an ultrasonic frequency of 25 - 30 kHz to obtain the melt tube blank.

10. A biodegradable packaging film bag for medical fabrics, characterized in that: The raw materials for preparing the biodegradable packaging film bag include modified starch, aminated nanocrystalline cellulose and a synergistic antibacterial compatibilizer; the biodegradable packaging film bag is prepared by the preparation method described in any one of claims 1 - 9.

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