Anaerobic biodegradable masterbatch for hygiene material cast film, cast film and preparation method thereof

Abstract

This invention discloses an anaerobic biodegradable masterbatch for cast film of sanitary materials, characterized in that its main components, by mass percentage, include: 0.5-3% cypermethrin, 3-6% copper sulfate, 0.1-0.5% metal inorganic salt coating agent, 1-4% ammonium molybdate, 5-10% PLA, 5-10% nano starch, 1-5% carbamide, 7-12% fumed silica, and the balance being a biodegradable resin carrier. The preparation method includes dispersion treatment, centering treatment, structuring treatment, carrier implantation, and plasticizing granulation. The invention also discloses an anaerobic biodegradable cast film for sanitary materials, comprising the following components by mass percentage: 83.4%-97.13% PE-based cast film substrate for sanitary materials, 1-5% PE wax, 1-7.5% degradation masterbatch, 0.15-0.3% dispersant, 0.02-0.2% antioxidant, 0.2-0.6% white oil, 0.5-3% PE grafted maleic anhydride, and 0.2-2% stabilizer. The manufacturing method includes: material preparation, calcium carbonate pretreatment, melting, filtration, and casting. This invention achieves complete anaerobic biodegradation of PE cast leak-proof and breathable films, and also has antibacterial properties during normal use, making it suitable as a breathable film and base film for disposable sanitary materials.

Description

Technical Field

[0001] This invention relates to cast film for sanitary products such as sanitary napkins, diapers, and panty liners, specifically a waterproof and breathable membrane material that can be biodegraded under anaerobic conditions. Background Technology

[0002] Currently, PE cast film is widely used in disposable hygiene products, mainly including breathable films and leak-proof bottom films for sanitary napkins, baby diapers, and sanitary pads used by patients, serving the functions of breathability and leak prevention, respectively. PE cast film is a flat-extruded film produced from raw materials such as polyethylene (LDPE, LLDPE, HDPE) and masterbatch through melt casting and rapid cooling. It is a controllable stretching and controllable orientation flat-extruded film with advantages such as good breathability, low moisture permeability, transparency, softness, and uniform thickness. Among them, common PE permeable cast film differs from leak-proof films with a PE content of over 90% in that it adds about 50% calcium carbonate to polyethylene resin to form the cast film substrate. Through casting and stretching processes, when the polyethylene resin, as a thermoplastic material, is stretched under certain conditions, interfacial delamination occurs between the polymer and calcium carbonate particles, forming interconnected, meandering pores or channels around the calcium carbonate particles, giving the film its breathability.

[0003] Because PE degrades very slowly under natural conditions, and disposable hygiene materials are used only once and then discarded, cast films used in hygiene materials have become a source of white pollution. To accelerate the degradation of polyethylene cast films, the common practice is to add biodegradable natural polymers such as starch and cellulose to the polyethylene material. For example, CN115838507A discloses a high-strength biodegradable polyethylene cast film and its preparation method, whose main components are matrix resin, calcium carbonate, starch, plasticizers, and modifying agents. However, this type of degradable plastic, achieved by adding natural degradable materials such as starch and cellulose, essentially only degrades the starch and cellulose molecules; the PE molecules do not degrade (strictly speaking, the degradation is extremely slow). Therefore, this type of plastic is now called disintegration. The disintegrated PE plastic exists in the environment in the form of microparticles, known as microplastics. Existing research is gradually recognizing that microplastics can enter organisms and cause unpredictable micro-harm, and researchers have obtained increasing evidence linking various diseases to microplastics.

[0004] Based on research conducted in collaboration with several domestic research institutions, the applicant has developed a fully biodegradable anaerobic material and filed a Chinese patent application (No. 2023117421187) entitled "An Anaerobic Degradable Composite Yeast Agent, Production Method, and Anaerobic Biodegradable Plastic." This composite yeast agent, when added at 1-5% to synthetic resin substrates such as PE and PP, enables significant degradation of PE and PP under anaerobic conditions, and only partial degradation of the added biodegradable material under aerobic conditions, while the PE and PP substrates largely retain their original properties, thus maintaining their long-term applicability. Based on this achievement, and considering the specific performance requirements of the melt for cast film casting, the applicant further improved the original invention according to the characteristics of PE permeable cast films used in sanitary materials, thus arriving at this invention. Summary of the Invention

[0005] To address the issue that existing PE permeable cast films cannot achieve complete biodegradation, especially under anaerobic conditions, the present invention aims to provide an anaerobic biodegradable masterbatch, a sanitary material cast film using this masterbatch, and a method for preparing the same. This invention achieves complete biodegradation of PE and PP polymers under anaerobic conditions while also exhibiting antibacterial effects and maintaining long-lasting performance.

[0006] To achieve the first objective of this invention, the anaerobic biodegradable masterbatch for cast films of sanitary materials of this invention comprises, by weight percentage: Cypermethrin 0.5-3% Copper sulfate 3-6% Metal inorganic salt coating agent 0.1-0.5% Ammonium molybdate 1-4% PLA 5-10% Nano starch 5-10% Carboamide 1-5% Fumed silica 7-12% Remaining amount of biodegradable resin carrier.

[0007] The nano starch can be nano corn starch or mung bean starch, preferably mung bean starch that has been modified by soaking in a weak acid or weak alkaline sodium chloride solution and then drying.

[0008] The biodegradable resin carrier is one or more of PBAT, PHA, PLA, and PHB.

[0009] The metal inorganic salt coating agent can be polytetrafluoroethylene and / or phthalate to modify the surface of the metal inorganic salt, thereby preventing the agglomeration of copper sulfate during granulation and film-making processes.

[0010] The present invention also provides a method for preparing the above-mentioned degradation masterbatch, comprising the following steps: (1) Dispersion treatment: PLA is ground to nanoscale, nano starch is added and mixed, and then titanate and anhydrous ethanol are added and ground; copper sulfate is mixed with metal inorganic salt coating agent and surface modified coating treatment is performed on copper sulfate. (2) Centralization treatment: Mix the carbamide with the material that has been dispersed in step (1), then add white oil, then add fumed silica and mix well, and perform centralization protection; (3) Structural treatment: Cypermethrin, copper sulfate and ammonium molybdate are ground into nano-sized powders, and then some resin base powder is added and ground evenly to form a structural framework material. (4) Carrier implantation: Add resin carrier with a particle size of less than 10 micrometers and plastic additives such as stabilizer and compatibilizer to the materials of the central treatment in step (2) and the structuring treatment in step (3), and mix evenly; (5) Plasticizing and granulating: The mixed particles from step (4) are extruded and granulated.

[0011] Preferably, in step (1), the PLA is ground at a low temperature of -10 to -5°C. The low temperature helps to weaken the van der Waals forces between PLA molecules, increasing its brittleness and making it easier to grind.

[0012] Preferably, in step (2), the carbonamide is first dehumidified by drying air at 12-15°C, and then mixed with the material dispersed in step (1) in a dry environment at 20-22°C to avoid the carbonamide from absorbing moisture, dissolving, and decomposing.

[0013] The present invention also provides an anaerobic biodegradable sanitary material cast film, comprising the following components in weight percentage: PE-based cast film substrate for sanitary materials: 83.4%-97.13% PE wax 1-5% The degradation masterbatch of claim 1 is 1-7.5%. Dispersant 0.15-0.3% Antioxidant 0.02-0.2% White oil 0.2-0.6% PE grafted with maleic anhydride 0.5-3% Stabilizer 0.2-2%.

[0014] Furthermore, the PE-based cast film substrate used in the sanitary materials serves as the main component and basic material of the cast film, and the composition differs for breathable films and leak-proof films. For breathable films, the PE-based cast film substrate is preferably formed by using LLDPE3518, HDPE2911, and nano-calcium carbonate together to form the breathable cast film substrate. The mass percentage of each component in the cast film is as follows: LLDPE3518 22-32%, HDPE2911 15-20%, and nano-calcium carbonate 50-55%. For the leak-proof film, the PE-based cast film substrate is preferably composed of LDPE7042, LDPE2426, HDPE2911, LLDPE3518CB, PPT30S, and color masterbatch. The mass percentage of each component in the cast film is as follows: LDPE7042 28-35%, LDPE2426 20-25%, HDPE2911 15-18%, LLDPE3581CB 10-15%, PPT30S 5-8%, and color masterbatch 5-6%.

[0015] Preferably, the dispersant is a combination of Kao dispersant and erucamide, wherein the percentage of each component in the cast film is 0.075-0.15% for Kao and 0.075-0.15% for erucamide. This invention utilizes the low melting point of erucamide, the high melting point of Kao dispersant EBS, and the liquid nature of white oil to allow it to function effectively in different sections of the screw extruder under different material melting states. It also works in conjunction with white oil to reduce the frictional resistance between the degradation masterbatch and PP / PE, thereby preventing the decomposition of carbamide and ammonium molybdate in the degradation masterbatch and improving the overall flowability of the material.

[0016] The preferred antioxidant is a combination of antioxidant 1010 and antioxidant 626. Antioxidant 1010 is a hindered phenolic antioxidant with a melting point of 110-125℃, and antioxidant 626 is a phosphite antioxidant with a melting point of 170-180℃.

[0017] The stabilizer is one or more of tert-dodecyl mercaptan, mercaptoethanol, mercaptoacetic acid, AMSD, Kristalex 5140 and Kristalex 3100. The present invention adjusts the uniformity of the molecular weight distribution of the material by adding stabilizers, reduces the viscosity of the material in the molten state, and facilitates casting and film formation.

[0018] This invention also provides a method for preparing an anaerobic biodegradable permeable gas-cast membrane, comprising the following steps: (1) Material preparation: Prepare all materials according to the above-mentioned components and their mass percentage requirements; (2) Pretreatment of calcium carbonate: For breathable membranes, calcium carbonate should be mixed with metal inorganic salt coating agent for surface modification first, and then dispersant and white oil should be added for pretreatment. (3) Melting: Add the degradation masterbatch and other raw materials to the screw extruder, control the temperature at 135-220℃, so that the raw materials are mixed evenly and melted into a melt; (4) Filtration: The melt is filtered using a multi-stage filter with a mesh size distribution of 30-230. (5) Casting film: The filtered melt is cast, cooled and stretched into a permeable cast film through a molding die.

[0019] For breathable membranes, since polyethylene is a non-polar polymer and calcium carbonate has a highly polar surface, the two have poor compatibility. Furthermore, calcium carbonate is prone to agglomeration and is used in large quantities, requiring a very high degree of dispersion. It must be uniformly dispersed without agglomeration, otherwise it will lead to large-pore leakage and blockage of the extruder filter screen. In this invention, in addition to adding a dispersant, a metal inorganic salt coating agent is first added for surface modification to inhibit the agglomeration of calcium carbonate in the resin during processing. The metal inorganic salt coating agent in step (2) can be polytetrafluoroethylene and / or phthalate.

[0020] Preferably, the filtration adopts a single-stage filtration, and the mesh sizes of the three-stage filter screens are 30 / 230 / 30 respectively.

[0021] The present invention has the following beneficial effects: The anaerobic biodegradable permeable cast film of the present invention uses degradation masterbatch as the anaerobic biodegradable material. Not only can the degradation masterbatch dispersed in the cast film undergo complete biodegradation under anaerobic conditions, but the specific anaerobic degradation environment created by the degradation masterbatch also induces the biodegradation of the cast film (PE, etc.), achieving complete biodegradation of the anaerobic biodegradable permeable cast film and solving the problem of the hazards caused by microplastics formed by the disintegration of traditional degradable PE cast films. Furthermore, the anaerobic biodegradable permeable cast film of the present invention also has antibacterial properties during normal use, making it suitable as a breathable membrane or base film for disposable hygiene materials. Detailed Implementation

[0022] To facilitate a full understanding of the present invention, the present invention will be further described below with reference to examples, but these specific embodiments are not intended to limit the scope of protection of the present invention.

[0023] I. Anaerobic Degradation Masterbatch and its Preparation In the following embodiments, the anaerobic degradation masterbatch used includes degradation masterbatch 1, degradation masterbatch 2 and degradation masterbatch 3, which are described below.

[0024] 1. Degradation Masterbatch 1 The components of the degradation masterbatch 1, by weight percentage, are: cypermethrin 2%, copper sulfate 4%, ammonium molybdate 3%, PLA 8%, nano mung bean starch 8%, carbamide 3.6%, fumed silica 10%, polytetrafluoroethylene 0.3%, titanate 1%, anhydrous ethanol 1%, compatibilizer 1%, filler 1%, and the balance is PBAT.

[0025] The preparation method is as follows: (1) Dispersed treatment 1) Grind PLA particles to nanoscale at -10 to -5℃; modify mung bean starch by soaking it in sodium chloride (2-5%wt) at pH 6.5 for 3-5 days and then dry it; add the modified and dried mung bean starch to the nano PLA powder, and then mix and grind it for 5 minutes to obtain a nano-mixed material; mix copper sulfate and polytetrafluoroethylene at 70-100℃ using a high-speed mixer (800-1200rpm) for 30-60 minutes to perform surface modification and coating treatment on the copper sulfate. 2) Add titanate with a particle size of less than 5 micrometers to the above nano-mixed material and stir and disperse it evenly in a high-speed mixer; 3) Add anhydrous ethanol and grind at high speed at a low temperature of -10 to -5℃ three times, 3 minutes each time, with a time interval of 1 hour, to carry out the pretreatment chemical reaction and form a dispersible treatment material.

[0026] (2) Centralized processing 1) Dehumidify the carbamide with dry air at a temperature of 12-15℃ for 2 hours; 2) Mix the dehumidified carbamide with the dispersible material in a dry environment at 20-22°C at low speed (below 200 rpm) for 25-30 minutes; then add a small amount of white oil and mix for 5 minutes. 3) Add fumed silica and mix clockwise at medium speed (400-600 rpm) for 10 minutes at 18-20℃ for center protection.

[0027] (3) Structural processing Accelerator protection treatment: Cypermethrin, coated copper sulfate, and ammonium molybdate are ground into nano-sized powders, and then 30% of resin-based PBAT powder is added and ground evenly to form the material structure. (4) Carrier implantation: Add the materials from the centralization treatment in step (2) and the structuring treatment in step (3) to the remaining amount of PBAT resin carrier and plastic additives with a particle size of less than 10 micrometers, and mix them evenly; (5) Plasticizing and granulating: The mixed particles from step (4) are extruded and granulated; (6) Stabilization treatment: The particles produced in step (5) are mixed with tert-dodecyl mercaptan to obtain anaerobic biodegradable masterbatch.

[0028] 2. Degradation Masterbatch 2 The components of the degradation masterbatch 2, by weight percentage, are: 0.6% cypermethrin, 6% copper sulfate, 1.2% ammonium molybdate, 10% PLA, 5.2% nano mung bean starch, 1.2% carbamide, 12% fumed silica, 1% titanate, 1% anhydrous ethanol, 1% compatibilizer, 1% filler, and the balance is PBAT.

[0029] The production method is the same as that for degradation masterbatch 1.

[0030] 3. Degradation masterbatch 3 The components of the degradation masterbatch 3, by weight percentage, are: cypermethrin 3%, copper sulfate 3%, ammonium molybdate 4%, PLA 5%, nano mung bean starch 9.8%, carbamide 5%, fumed silica 7%, titanate 1%, anhydrous ethanol 1%, compatibilizer 1%, filler 1%, and the balance is PLA.

[0031] The production method is the same as that of degradation masterbatch 1. In steps (3) and (4), the resin is basically replaced with PLA instead of PBAT.

[0032] II. Breathable / Leak-proof Cast Film for Anaerobic Biodegradable Sanitary Materials In the following embodiments, the main resin brands used are: PE3518 is an ExxonMobil product.

[0033] PE2911 is a Sinopec product. LDPE7042 is a product of Sinopec.

[0034] LDPE2426 is a product of Sinopec.

[0035] PPT30S Zhongyuan Petrochemical PE wax, made in South Korea, softening point 113±5℃, viscosity (CPS@140℃) 30+10.

[0036] Nano-calcium carbonate, with a particle size of 60-300nm.

[0037] 1. Examples 1-6: Permeable Cast Film for Sanitary Materials The components and component contents of the anaerobic biodegradable sanitary material permeable cast film in Examples 1-6 are shown in Table 1.

[0038] Table 1. Composition and mass percentage of components in Examples 1-6 The preparation methods of the permeable cast film as a sanitary material in Examples 1-6 above are as follows: (1) Material preparation: Prepare all materials according to the above-mentioned components and their mass percentage requirements; (2) Pretreatment of calcium carbonate: First, mix calcium carbonate and polytetraoxide at 70-100℃ using a high-speed mixer at a speed of 800-1200rpm for 30-60min. Then, add dispersant and white oil and mix at a medium speed of 400-600rpm for 2-3min for pretreatment. (3) Melting: Add the degraded masterbatch, pretreated calcium carbonate and other raw materials to the screw extruder, control the temperature at 135-220℃, so that the raw materials are mixed evenly and melted into a melt; (4) Filtration: The melt is filtered using a three-stage filter with a mesh size distribution of 30 / 230 / 30. (5) Casting film: The filtered melt is cast, cooled and stretched into a permeable cast film through a molding die.

[0039] 2. Cast film for leak-proof bottom film of sanitary materials (Examples 7-10) The components and component contents of the anaerobic biodegradable leak-proof bottom film of Examples 7-10 within the scope of protection of this invention are shown in Table 2. Table 2. Component composition and mass percentage of Examples 7-10 The preparation method of the leak-proof cast film of the above Examples 7-10 as sanitary materials is as follows: (1) Material preparation: Prepare all materials according to the above-mentioned components and their mass percentage requirements; (2) Melting: Add the degradation masterbatch and other raw materials to the screw extruder, control the temperature at 135-220℃, so that the raw materials are mixed evenly and melted into a melt; (3) Filtration: The melt is filtered using a three-stage filter with a mesh size distribution of 30 / 230 / 30. (4) Casting film: The filtered melt is cast, cooled and stretched into a permeable cast film through a molding die.

[0040] 2. Comparative Example 1 Comparative Example 1 uses corn starch instead of the degradation masterbatch in Example 1.

[0041] III. Degradation Experiment 1. Anaerobic degradation detection According to the standard GB / T 33797-2017, "Determination of the Final Anaerobic Biodegradability of Plastics under High Solids Composting Conditions by Analytical Determination of Released Biogases," the degradation rates of the degradable plastic films in Examples 1-10 and Comparative Example 1 were tested. This method is used to determine the anaerobic decomposition rate, specifically by measuring the carbon content in the test material and the percentage of carbon dioxide and methane converted after degradation as the degradation rate. The test results are shown in Table 3 below. Table 3 Anaerobic degradation rate (%) of different materials As shown in Table 3, among the breathable membrane examples 1-6, Example 1 is the preferred example, exhibiting better degradation performance than Examples 2-6. Furthermore, Example 1's degradation performance is also superior to Examples 2 and 3, indicating that degradation masterbatch 1 has better degradation performance than degradation masterbatch 2 and 3. The degradation performance of Example 6 is lower than that of Examples 1-5, proving that the combination of dispersant and antioxidant used in Examples 1-5 is superior to the single dispersant and antioxidant used in Example 6. Similarly, as shown in Table 3, among the leak-proof membrane examples 7-10, Example 7 is the best example, indicating that adjusting the component content affects the degradation performance. Comparing Comparative Example 1 with Example 1, which uses corn starch instead of the degradation masterbatch, the degradation performance of Comparative Example 1 is much slower than that of Example 1, demonstrating that the degradation masterbatch of the present invention significantly promotes anaerobic degradation.

[0042] 2. Aerobic degradation detection The anaerobic degradable plastic film from Example 1 was tested for degradation rate under aerobic conditions according to GB / T 19277.1-2011 "Determination of the final aerobic biodegradability of materials under controlled composting conditions by measuring the amount of carbon dioxide released". The results showed that the degradation rate after 90 days was [missing information]. 1.17 The percentage is significantly lower than the anaerobic degradation rate, proving that under aerobic conditions, only PBAT and PLA, which are inherently biodegradable materials, may have degraded, while HDPE remained undegraded. This effect is beneficial for maintaining the durability of the degradable plastic's properties under normal use (aerobic environment).

[0043] 3. Antibacterial performance test According to GB15979-2002 "Hygienic Standard for Disposable Sanitary Products", disposable sanitary products are required to have antibacterial properties, especially against Escherichia coli and Staphylococcus aureus. Antibacterial tests were conducted on Examples 1 and 3 and Comparative Example 1 of the present invention, and the antibacterial rate results are shown in Table 4.

[0044] Table 4 Results of antibacterial test As can be seen from Table 4, the degradation masterbatch of this application also has antibacterial effects against Escherichia coli and Staphylococcus aureus, making it suitable for use in sanitary materials.

[0045] It will be understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An anaerobic biodegradable masterbatch for cast film of sanitary materials, characterized in that... Its main components, by mass percentage, include: Cypermethrin 0.5-3% Copper sulfate 3-6% Metal inorganic salt coating agent 0.1-0.5% Ammonium molybdate 1-4% PLA 5-10% Nano starch 5-10% Carboamide 1-5% Fumed silica 7-12% Remaining amount of biodegradable resin carrier.

2. The degradation masterbatch as described in claim 1, characterized in that: The nano starch is nano corn starch or mung bean starch.

3. The degradation masterbatch as described in claim 2, characterized in that: The nano-mung bean starch is mung bean starch that has been modified by soaking in a weak acid or weak alkaline sodium chloride solution and then drying.

4. The degradation masterbatch as described in claim 2, characterized in that: The metal inorganic salt coating agent is polytetrafluoroethylene and / or phthalate.

5. The degradation masterbatch as described in any one of claims 1-3, characterized in that: The biodegradable resin carrier is one or more of PBAT, PHA, PLA, and PHB.

6. A method for preparing the degradation masterbatch according to claim 1, comprising the following steps: (1) Dispersion treatment: PLA is ground to nanoscale, nano starch is added and mixed, and then titanate and anhydrous ethanol are added for grinding treatment; copper sulfate is mixed with metal inorganic salt coating agent to perform surface modification coating treatment on copper sulfate. (2) Centralization treatment: Mix the carbamide with the material that has been dispersed in step (1), then add white oil, then add fumed silica and mix well, and perform centralization protection; (3) Structural treatment: Cypermethrin, coated copper sulfate and ammonium molybdate are ground into nano-sized powders, and then some resin base powder is added and ground evenly to form a structural framework material. (4) Carrier implantation: Add resin carrier and plastic additives with a particle size of less than 10 micrometers to the materials of the centralization treatment in step (2) and the structuring treatment in step (3), and mix evenly; (5) Plasticizing and granulating: The mixed particles from step (4) are extruded and granulated.

7. The preparation method according to claim 6, characterized in that: In step (1), the PLA is ground at a low temperature of -10 to -5℃.

8. The preparation method according to claim 6, characterized in that: In step (2), the carbonamide is first dehumidified by drying air at 12-15°C, and then mixed with the material dispersed in step (1) in a dry environment at 20-22°C.

9. A cast film for anaerobic biodegradable sanitary materials, characterized in that, It contains the following components in percentage by mass: PE-based cast film substrate for sanitary materials: 83.4%-97.13% PE wax 1-5% The degradation masterbatch of claim 1 contains 1-7.5%. Dispersant 0.15-0.3% Antioxidant 0.02-0.2% White oil 0.2-0.6% PE grafted with maleic anhydride 0.5-3% Stabilizer 0.2-2%.

10. The cast film as described in claim 9, characterized in that: The PE-based cast film substrate for sanitary materials is formed by using LLDPE3518, HDPE2911, and nano-calcium carbonate to form a PE-based permeable cast film substrate. The mass percentage of each component in the cast film is 22-32% for LLDPE3518, 15-20% for HDPE2911, and 50-55% for nano-calcium carbonate. Alternatively, the PE-based cast film substrate for sanitary materials is formed by using LDPE7042, LDPE2426, HDPE2911, LLDPE3518CB, PPT30S, and color masterbatch to form a leak-proof cast film substrate. The mass percentage of each component in the cast film is 28-35% for LDPE7042, 20-25% for LDPE2426, 15-18% for HDPE2911, 10-15% for LLDPE3518CB, 5-8% for PPT30S, and 5-6% for color masterbatch.

11. The cast film as described in claim 9, characterized in that: The dispersant is a combination of Kao EBS and erucamide, wherein the percentage of each component in the cast film is 0.075-0.15% for Kao EBS and 0.075-0.15% for erucamide.

12. The cast film as described in claim 9, characterized in that: The stabilizer is one or more of tert-dodecyl mercaptan, mercaptoethanol, mercaptoacetic acid, AMSD, Kristalex 5140, and Kristalex 3100.

13. A method for preparing a cast film for sanitary materials according to claim 9, characterized in that... The process includes the following: (1) Material preparation: Prepare all materials according to the above-mentioned components and their mass percentage requirements; (2) Pretreatment of calcium carbonate: For breathable membranes, calcium carbonate is first mixed with metal inorganic salt coating agent for surface modification, and then dispersant and white oil are added for pretreatment. (3) Melting: Add the degradation masterbatch and other raw materials to the screw extruder, control the temperature at 135-220℃, so that the raw materials are mixed evenly and melted into a melt; (4) Filtration: The melt is filtered using a multi-stage filter with a mesh size distribution of 30-230. (5) Casting film: The filtered melt is cast, cooled and stretched into a cast film through a molding die.

14. The method for preparing a permeable cast film as described in claim 13, wherein the metal inorganic salt coating agent in step (2) is polytetrafluoroethylene and / or phthalate.

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