Biodegradable non-woven fabric and preparation method thereof

Abstract

The present application relates to the field of non-woven fabric technology, and specifically discloses a biodegradable non-woven fabric and its preparation method. The non-woven fabric is mainly made of the following raw materials in parts by weight: 100 parts of polypropylene, 1-2 parts of biodegradable masterbatch, 6-8 parts of modified chitosan, 3-5 parts of maleic anhydride grafted polypropylene, and 1-2 parts of antioxidant; the modified chitosan is obtained by treating chitosan with sodium hydroxide, 1-chlorododecane, and 4-(2-chloroethane acylamino) ethyl benzoate. The biodegradable non-woven fabric has the advantages of high breaking strength and good degradability, expands the scope of application, can solve the environmental pollution problem caused by the difficulty of degradation of traditional polypropylene non-woven fabrics, and meets market demand.

Description

Technical Field

[0001] The present application relates to the technical field of non-woven fabrics, and more specifically, to a biodegradable non-woven fabric and a preparation method thereof. Background Art

[0002] As an important material, non-woven fabrics have been widely used in the fields of medical care, industry, agriculture, etc. In recent years, with the increasing attention paid to environmental issues, more and more researchers have begun to focus on biodegradable materials to reduce the impact on the environment. Traditional non-woven fabrics are made from polypropylene or polyethylene. Although they have the advantage of low cost, they are difficult to degrade after long-term use, which places a heavy burden on the environment. Based on this, the development of a biodegradable non-woven fabric has become a new topic to meet market demand and expand industry applications. Summary of the Invention

[0003] In order to improve the degradability of non-woven fabrics, the present application provides a biodegradable non-woven fabric and a preparation method thereof.

[0004] In a first aspect, the present application provides a biodegradable non-woven fabric, which adopts the following technical solution:

[0005] A biodegradable non-woven fabric is mainly made of the following raw materials in parts by weight: 100 parts of polypropylene, 1-2 parts of biodegradable masterbatch, 6-8 parts of modified chitosan, 3-5 parts of maleic anhydride grafted polypropylene, and 1-2 parts of an antioxidant; the modified chitosan is obtained by treating chitosan with sodium hydroxide, 1-chlorododecane, and ethyl 4-(2-chloroethane acylamino)benzoate.

[0006] The biodegradable non-woven fabric of the present application, through the mutual cooperation between the raw materials, has a longitudinal breaking strength of >74N, a transverse breaking strength of >60N, and a 180-day degradation rate of >90%. It shows the advantages of high breaking strength and good degradability, meets market demand, and can solve the environmental pollution problem caused by the difficulty of degradation of traditional polypropylene non-woven fabrics.

[0007] The non-woven fabric is made of polypropylene as the main raw material. On this basis, maleic anhydride grafted polypropylene is added to the raw material to increase the compatibility between the raw materials. Biodegradable masterbatch and modified chitosan are added to the raw material, and the mutual coordination therebetween is utilized to improve the degradation rate and enhance the degradability without affecting the breaking strength of the non-woven fabric, so that the non-woven fabric shows better mechanical properties. Further, 1-chlorododecane and 4-(2-chloroethane acylamino) ethyl benzoate are used to treat chitosan, and active groups such as dodecyl, ester group, and amide group are introduced on the surface of chitosan to increase the compatibility of the modified chitosan and the bonding force and integrity between the raw materials. Without affecting the degradation rate of the non-woven fabric, the breaking strength of the non-woven fabric is significantly increased, so that the non-woven fabric shows better mechanical properties.

[0008] Optionally, the modified chitosan is prepared by the following method:

[0009] S1. Mix water, isopropyl ketone, chitosan, sodium hydroxide, and tetramethylammonium hydroxide at a temperature of 40-60° C., and stir for 1-3 hours to obtain a chitosan alkaline solution;

[0010] S2. Add 1-chlorododecane and ethyl 4-(2-chloroethaneylamino)benzoate to the chitosan alkaline solution at a temperature of 60-80° C., keep the temperature for 7-9 hours, cool to room temperature, adjust the pH to 6.5-7.5, add acetone for precipitation, filter, wash, and dry to obtain modified chitosan.

[0011] Optionally, the weight ratio of the chitosan, sodium hydroxide, 1-chlorododecane and ethyl 4-(2-chloroethaneylamino)benzoate is 10:(9-11):(4-6):(4-6).

[0012] By adopting the above technical solution, chitosan is first alkalized with sodium hydroxide to convert the -OH groups on the chitosan surface into -ONa, and then the chlorine groups in 1-chlorododecane and 4-(2-chloroethane acylamino) ethyl benzoate are substituted to achieve grafting. The chitosan modification method of the present application not only facilitates the preparation of modified chitosan, but also limits the addition amounts of sodium hydroxide, 1-chlorododecane, and 4-(2-chloroethane acylamino) ethyl benzoate to ensure the grafting amount, and also ensures the stability and use effect of the modified chitosan.

[0013] Optionally, the weight ratio of the chitosan, water, isopropyl ketone, tetramethylammonium hydroxide and acetone is 10:(15-25):(70-90):(1-3):(80-120).

[0014] By employing the above technical solution, the addition amounts of water, isopropyl ketone, and tetramethylammonium hydroxide were optimized to ensure thorough mixing of chitosan, sodium hydroxide, 1-chlorododecane, and ethyl 4-(2-chloroethaneylamino)benzoate, facilitating the reaction. The addition amount of acetone was also optimized to ensure sufficient precipitation of the modified chitosan, ensuring the stability of the modified chitosan preparation.

[0015] Optionally, the deacetylation degree of the chitosan is 85-95%.

[0016] By adopting the above technical solution, the deacetylation degree of chitosan is optimized, which facilitates the selection of chitosan, while also ensuring the solubility and physical properties of chitosan, and facilitating the modification of chitosan. In multiple embodiments, the deacetylation degree of chitosan is 90%. It can also be set to 85%, 88%, 83%, or 95% as needed, but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0017] Optionally, the average molecular weight of the chitosan is 50,000-150,000. In multiple embodiments, the average molecular weight of the chitosan is 50,000. The average molecular weight can also be set to 70,000, 100,000, 130,000, or 150,000 as needed, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0018] Optionally, in step S2, a hydrochloric acid aqueous solution is used to adjust the pH value to 6.5-7.5, and the mass concentration of the hydrochloric acid aqueous solution is 5-10%.

[0019] By adopting the above technical solution, the pH value is adjusted by using hydrochloric acid aqueous solution, which is simple and convenient. The mass concentration of the hydrochloric acid aqueous solution is also limited, which is convenient for the preparation and use of the hydrochloric acid aqueous solution.

[0020] Optionally, the polypropylene has a melt index of 30-40 g / 10 min at 230° C. and 2.16 kg.

[0021] By adopting the above technical solution, the melt index of polypropylene is limited, ensuring a stable source of polypropylene and the quality and stability of the nonwoven fabric. In various embodiments, the melt index of polypropylene at 230°C and 2.16 kg is 35 g / 10 min. The melt index can also be set to 30 g / 10 min, 33 g / 10 min, 38 g / 10 min, or 40 g / 10 min as needed, but is not limited to the listed values. Other values ​​not listed within this range are also applicable.

[0022] Optionally, the maleic anhydride grafted polypropylene has a melt index of 100-150 g / 10 min at 230° C. and 2.16 kg.

[0023] By adopting the above technical solution, the melt index of maleic anhydride grafted polypropylene is limited, ensuring sufficient mixing of the raw materials, increasing the compatibility of the raw materials, facilitating the processing of the non-woven fabric, and improving the mechanical properties of the non-woven fabric. In various embodiments, the melt index of the maleic anhydride grafted polypropylene at 230°C and 2.16 kg is 120 g / 10 min. The melt index can also be set to 100 g / 10 min, 110 g / 10 min, 130 g / 10 min, 140 g / 10 min, or 150 g / 10 min as needed, but is not limited to the listed values. Other values ​​not listed within this range are also applicable.

[0024] Optionally, the antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant 264, and antioxidant 626.

[0025] By adopting the above technical solution, antioxidants are optimized, which facilitates the selection of antioxidants.

[0026] Optionally, the antioxidants include antioxidant 1010 and antioxidant 1076, and the weight ratio of antioxidant 1010 to antioxidant 1076 is (1-3):(1-3). In various embodiments, the weight ratio of antioxidant 1010 to antioxidant 1076 is 1:1. The weight ratio can also be set to 1:2, 1:3, 2:1, 2:3, 3:1, or 3:2 as needed, but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0027] In a second aspect, the present application provides a method for preparing the biodegradable non-woven fabric, which adopts the following technical solution:

[0028] A method for preparing the biodegradable non-woven fabric comprises the following steps:

[0029] T1. Mixing polypropylene, biodegradable masterbatch, modified chitosan, maleic anhydride grafted polypropylene, and antioxidant to obtain a mixture;

[0030] T2. Heat and melt the mixture, extrude, spin, draw, and lay a web to obtain a non-woven fabric.

[0031] By adopting the above technical solution, the preparation of non-woven fabrics is facilitated.

[0032] Optionally, in step T2, the melting temperature is 250-270° C. In various embodiments, the melting temperature is 265° C., and the melting temperature may be set to 250° C., 255° C., 260° C., or 270° C. as needed, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] Optionally, in step T2, the spinning temperature is 240-260° C. In various embodiments, the melting temperature is 250° C., and the spinning temperature can be set to 240° C., 245° C., 255° C., or 260° C. as needed, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0034] Optionally, in step T2, the stretching temperature is 250-270° C. In many embodiments, the melting temperature is 260° C., and the stretching temperature can also be set to 250° C., 255° C., 265° C., or 270° C. as needed, but is not limited to the listed values. Other values ​​not listed in the numerical range are also applicable.

[0035] Optional, non-woven fabric weight is 20-30g / m 2 In various embodiments, the nonwoven fabric has a grammage of 25 g / m 2 The non-woven fabric weight can also be set to 20g / m2 as needed. 2 , 23g / m 2 , 28g / m 2 , 30g / m 2 , but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] In summary, this application has at least the following beneficial effects:

[0037] 1. The biodegradable non-woven fabric of the present application has the advantages of high breaking strength and good degradability through the mutual cooperation between the raw materials. The longitudinal breaking strength of the non-woven fabric is greater than 74N, the transverse breaking strength is greater than 60N, and the 180-day degradation rate is greater than 90%. It expands the scope of application and can solve the environmental pollution problem caused by the difficulty of degradation of traditional polypropylene non-woven fabrics.

[0038] 2. In the preparation method of modified chitosan of the present application, chitosan is first alkalized with sodium hydroxide, and then 1-chlorododecane and 4-(2-chloroethane acylamino) ethyl benzoate are grafted using chlorine groups, and active groups such as dodecyl groups, ester groups, and amide groups are introduced on the surface of chitosan to increase the compatibility of the modified chitosan and the binding force between the modified chitosan and the raw materials. On the basis of not affecting the degradation rate of the non-woven fabric, the breaking strength of the non-woven fabric is significantly increased, so that the non-woven fabric exhibits better mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a visual observation picture of the non-woven fabric in Example 1 of the present application before degradation.

[0040] Figure 2This is a visual observation picture of the degradation of the non-woven fabric in Example 1 of the present application for 180 days. DETAILED DESCRIPTION

[0041] To make this application easier to understand, the following examples will be used to further illustrate this application. These examples are for illustrative purposes only and are not intended to limit the scope of application of this application. Unless otherwise specified, the raw materials or components used in this application can be obtained through commercial channels or conventional methods.

[0042] Preparation Example

[0043] Preparation Example 1

[0044] A modified chitosan is prepared by the following method:

[0045] S1. Add 80 kg of isopropyl tone to 20 kg of water at 50°C and stir for 3 minutes. Then add 10 kg of chitosan, 10 kg of sodium hydroxide, and 2 kg of tetramethylammonium hydroxide and stir for 2 hours to obtain a chitosan alkaline solution.

[0046] The deacetylation degree of chitosan is 90% and the average molecular weight is 50,000.

[0047] S2. Add 5 kg of 1-chlorododecane and 5 kg of ethyl 4-(2-chloroethaneylamino)benzoate to the alkaline chitosan solution obtained in step S1 at 70°C. Keep the solution warm for 8 hours, then cool to 23°C. Adjust the pH to 7 with an 8% aqueous hydrochloric acid solution. Then, add 100 kg of acetone for precipitation. Filter the solution and wash it three times with 50 kg of acetone each time. Dry the solution to obtain modified chitosan.

[0048] Preparation Example 2

[0049] A modified chitosan is prepared by the following method:

[0050] S1. Add 90 kg of isopropyl tone to 15 kg of water at 50°C and stir for 3 minutes. Then add 10 kg of chitosan, 9 kg of sodium hydroxide, and 3 kg of tetramethylammonium hydroxide and stir for 1 hour to obtain a chitosan alkaline solution.

[0051] The deacetylation degree of chitosan is 90% and the average molecular weight is 50,000.

[0052] S2. At 70°C, add 4 kg of 1-chlorododecane and 6 kg of ethyl 4-(2-chloroethaneylamino)benzoate to the alkaline chitosan solution obtained in step S1. Keep the solution warm for 9 hours, then cool to 23°C. Adjust the pH to 6.5 with a 10% aqueous hydrochloric acid solution. Then, add 120 kg of acetone for precipitation. Filter the solution and wash it three times with 50 kg of acetone each time. Then, dry the solution to obtain modified chitosan.

[0053] Preparation Example 3

[0054] A modified chitosan is prepared by the following method:

[0055] S1. Add 70 kg of isopropyl tone to 25 kg of water at 50°C and stir for 3 minutes. Then add 10 kg of chitosan, 11 kg of sodium hydroxide, and 1 kg of tetramethylammonium hydroxide and stir for 3 hours to obtain a chitosan alkaline solution.

[0056] The deacetylation degree of chitosan is 90% and the average molecular weight is 50,000.

[0057] S2. At 70°C, add 6 kg of 1-chlorododecane and 4 kg of ethyl 4-(2-chloroethaneylamino)benzoate to the alkaline chitosan solution obtained in step S1. Keep the solution warm for 7 hours, then cool to 23°C. Adjust the pH to 7.5 with a 5% aqueous hydrochloric acid solution. Then, add 80 kg of acetone for precipitation. Filter the solution and wash it three times with 50 kg of acetone each time. Dry the solution to obtain modified chitosan.

[0058] Example

[0059] Table 1 Amount of each raw material used in non-woven fabrics (unit: kg)

[0060] Example Example 1 Example 2 Example 3 Polypropylene 100 100 100 Biodegradable masterbatch 1.5 1 2 Modified chitosan 7 8 6 Maleic anhydride grafted polypropylene 4 5 3 antioxidants 1.5 1 2

[0061] Example 1

[0062] A biodegradable non-woven fabric, the raw materials and raw material ratios of which are shown in Table 1.

[0063] Among them, the melt index of polypropylene at 230°C and 2.16kg is 35g / 10min; the biodegradable masterbatch is biodegradable masterbatch JT-201, and is selected from Guangdong Limei New Material Technology Co., Ltd.; the melt index of maleic anhydride grafted polypropylene at 230°C and 2.16kg is 120g / 10min; the antioxidants are antioxidant 1010 and antioxidant 1076, and the weight ratio of antioxidant 1010 to antioxidant 1076 is 1:1; the modified chitosan is prepared by the method of Preparation Example 1.

[0064] A method for preparing a biodegradable non-woven fabric comprises the following steps:

[0065] T1. Add biodegradable masterbatch, modified chitosan, maleic anhydride grafted polypropylene, and antioxidant into polypropylene, and stir for 3 minutes to obtain a mixture.

[0066] T2. The mixed material is fed into a screw extruder, heated and melted at a temperature of 265° C., extruded, spun at a temperature of 250° C., stretched at a temperature of 260° C., and laid to obtain a non-woven fabric.

[0067] The speed of the screw extruder is 80r / min; the weight of the non-woven fabric is 25g / m 2 .

[0068] Example 2

[0069] A biodegradable non-woven fabric is different from Example 1 in that the raw material ratio of the non-woven fabric is different, and the raw material ratio is shown in Table 1.

[0070] Example 3

[0071] A biodegradable non-woven fabric is different from Example 1 in that the raw material ratio of the non-woven fabric is different, and the raw material ratio is shown in Table 1.

[0072] Example 4

[0073] A biodegradable non-woven fabric is provided, which differs from Example 1 in that the modified chitosan in the raw materials of the non-woven fabric has a different source, and the modified chitosan is prepared by the method of Preparation Example 2.

[0074] Example 5

[0075] A biodegradable non-woven fabric is different from Example 1 in that the modified chitosan in the raw materials of the non-woven fabric has a different source, and the modified chitosan is prepared by the method of Preparation Example 3.

[0076] Comparative Example

[0077] Comparative Example 1

[0078] A biodegradable non-woven fabric is provided, which differs from Example 1 in that an equal amount of polypropylene is used to replace the biodegradable masterbatch and modified chitosan in the raw materials of the non-woven fabric.

[0079] Comparative Example 2

[0080] A biodegradable non-woven fabric is different from Example 1 in that an equal amount of biodegradable masterbatch is used to replace modified chitosan in the raw materials of the non-woven fabric.

[0081] Comparative Example 3

[0082] A biodegradable non-woven fabric is different from Example 1 in that an equal amount of modified chitosan is used to replace the biodegradable masterbatch in the raw materials of the non-woven fabric.

[0083] Comparative Example 4

[0084] A biodegradable non-woven fabric is different from Example 1 in that an equal amount of chitosan is used to replace modified chitosan in the raw materials of the non-woven fabric.

[0085] Comparative Example 5

[0086] A biodegradable non-woven fabric is different from Example 1 in that, in the raw material of the non-woven fabric and in the preparation method of the modified chitosan, an equal amount of 1-chlorododecane is used to replace 4-(2-chloroethane acylamino) ethyl benzoate.

[0087] Comparative Example 6

[0088] A biodegradable non-woven fabric is different from Example 1 in that, in the raw materials of the non-woven fabric and in the preparation method of the modified chitosan, an equal amount of ethyl 4-(2-chloroethaneylamino)benzoate is used to replace 1-chlorododecane.

[0089] Performance testing

[0090] (1) The nonwoven fabrics obtained in Examples 1-5 and Comparative Examples 1-6 were taken as samples respectively. The breaking strength of the samples was tested according to GB / T 24218.3-2010 “Test methods for textiles, nonwoven fabrics—Part 3: Determination of breaking strength and elongation at break (strip method)”. The test results are shown in Table 2.

[0091] (2) The nonwoven fabrics obtained in Examples 1-5 and Comparative Examples 1-6 were respectively taken as samples, and the samples were composted and buried for 180 days in accordance with GBT 19277.1-2011 "Determination of the ultimate aerobic biodegradability of materials under controlled composting conditions by measuring the released carbon dioxide - Part 1: General method", and the degradation rates were calculated. The test results are shown in Table 2.

[0092] At the same time, positive control group and negative control group were prepared. The positive control group used TLC grade cellulose, and the negative control group used polyethylene.

[0093] At the same time, the non-woven fabric of Example 1 was visually observed before and after degradation and photographed. Figure 1 , Example 1 Non-woven fabric degradation 180 days visual observation picture see Figure 2 .

[0094] Degradation rate / (%) = (net weight of silicon dioxide produced (mg) × 100%) / (weight of sample (g) × ThCO2 (sample) (mgCO2 / g sample)); where ThCO2 is the maximum theoretical amount of carbon dioxide produced by complete oxidation of the compound.

[0095] ThCO2 / (mgCO2 / g)=TOC×(44 / 12); where 44 and 12 are the molecular mass of carbon dioxide and the atomic mass of carbon, respectively.

[0096] Table 2 Test results

[0097]

[0098]

[0099] As can be seen from Table 2, the nonwoven fabric of this application exhibits high breaking strength, with a longitudinal breaking strength of 74.1-76.3N and a transverse breaking strength of 60.6-62.5N, demonstrating superior mechanical properties. It also exhibits a high degradation rate, with a 180-day degradation rate of 90.5-93.6%, demonstrating excellent degradability. The nonwoven fabric of this application, through the interaction of its raw materials, has the advantages of high breaking strength and good degradability, meeting market demand.

[0100] Combine Figure 1 、 Figure 2 ,from Figure 1 It can be seen that the structure of the non-woven fabric is intact before degradation. Figure 2 It can be seen that there is less residue after 180 days of degradation of the non-woven fabric, and the 180-day degradation rate of the non-woven fabric reaches 93.6%.

[0101] Comparing Example 1 with Comparative Examples 1-3, the non-woven fabric of Comparative Example 1 contained neither biodegradable masterbatch nor modified chitosan; the non-woven fabric of Comparative Example 2 contained biodegradable masterbatch; the non-woven fabric of Comparative Example 3 contained modified chitosan; and the non-woven fabric of Example 1 contained both biodegradable masterbatch and modified chitosan. This indicates that the simultaneous addition of biodegradable masterbatch and modified chitosan to the raw materials of the non-woven fabric has little effect on the breaking strength of the non-woven fabric. However, the synergistic effect between the two can significantly increase the degradation rate, resulting in the non-woven fabric exhibiting superior degradability.

[0102] Comparing Example 1 with Comparative Examples 4-6, chitosan was added to the non-woven fabric of Comparative Example 4; chitosan modified with sodium hydroxide and 1-chlorododecane was added to the non-woven fabric of Comparative Example 5; chitosan modified with sodium hydroxide and ethyl 4-(2-chloroethane acylamino)benzoate was added to the non-woven fabric of Comparative Example 6; and chitosan modified with sodium hydroxide, 1-chlorododecane, and ethyl 4-(2-chloroethane acylamino)benzoate was added to the non-woven fabric of Example 1. It can be seen that the modification of chitosan has little effect on the degradation rate of the non-woven fabric. However, the simultaneous grafting of chitosan with 1-chlorododecane and ethyl 4-(2-chloroethane acylamino)benzoate, and the interaction between the two, can improve the compatibility of chitosan with the raw materials, increase the breaking strength of the non-woven fabric, and enable the non-woven fabric to exhibit better mechanical properties.

[0103] It should be noted that the embodiments described above are only used to explain the present application and do not constitute any limitation to the present application. The present application has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present application may be modified as specified within the scope of the claims of the present application, and the invention may be revised without departing from the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and embodiments, it does not mean that the present application is limited to the specific examples disclosed therein. On the contrary, the present application can be extended to all other methods and applications with the same function.

Claims

1. A biodegradable nonwoven fabric, characterized by: The invention is mainly made of the following raw materials in parts by weight: 100 parts of polypropylene, 1-2 parts of biodegradable masterbatch, 6-8 parts of modified chitosan, 3-5 parts of maleic anhydride grafted polypropylene, and 1-2 parts of antioxidant; the modified chitosan is obtained by treating chitosan with sodium hydroxide, 1-chlorododecane, and ethyl 4-(2-chloroethane acylamino)benzoate; The modified chitosan is prepared by the following method: S1. Mix water, isopropyl ketone, chitosan, sodium hydroxide, and tetramethylammonium hydroxide at a temperature of 40-60° C., and stir for 1-3 hours to obtain a chitosan alkaline solution; S2. Add 1-chlorododecane and ethyl 4-(2-chloroethaneylamino)benzoate to the chitosan alkaline solution at a temperature of 60-80° C., keep the temperature for 7-9 hours, cool to room temperature, adjust the pH to 6.5-7.5, add acetone for precipitation, filter, wash, and dry to obtain modified chitosan; The weight ratio of the chitosan, sodium hydroxide, 1-chlorododecane, and ethyl 4-(2-chloroethaneylamino)benzoate is 10:(9-11):(4-6):(4-6); the weight ratio of the chitosan, water, isopropyl ketone, tetramethylammonium hydroxide, and acetone is 10:(15-25):(70-90):(1-3):(80-120).

2. The biodegradable nonwoven fabric according to claim 1, wherein: The deacetylation degree of the chitosan is 85-95%.

3. The biodegradable nonwoven fabric according to claim 1, wherein: In step S2, the pH value is adjusted to 6.5-7.5 using a hydrochloric acid aqueous solution, and the mass concentration of the hydrochloric acid aqueous solution is 5-10%.

4. The biodegradable nonwoven fabric according to claim 1, wherein: The polypropylene has a melt index of 30-40 g / 10 min at 230° C. and 2.16 kg.

5. The biodegradable nonwoven fabric according to claim 1, wherein: The maleic anhydride grafted polypropylene has a melt index of 100-150 g / 10 min at 230° C. and 2.16 kg.

6. The biodegradable nonwoven fabric according to claim 1, wherein: The antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant 264, and antioxidant 626.

7. A method for preparing the biodegradable nonwoven fabric according to any one of claims 1 to 6, characterized in that: The steps include: T1. Mixing polypropylene, biodegradable masterbatch, modified chitosan, maleic anhydride grafted polypropylene, and antioxidant to obtain a mixture; T2. Heat and melt the mixture, extrude, spin, draw, and lay a web to obtain a non-woven fabric.

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