Spunlaced non-woven fabric for biodegradable wet tissue and preparation method of spunlaced non-woven fabric

Abstract

The invention provides a biodegradable wet tissue spunlaced non-woven fabric and a preparation method thereof, and the biodegradable wet tissue spunlaced non-woven fabric comprises the following raw materials in parts by weight: 40-50 parts of wood pulp cellulose, 20-30 parts of modified polylactic acid fiber with the length of 12-15 mm and the fineness of 1-2 dtex, 1-2.5 parts of alginate fiber with the length of 30-40 mm and the fineness of 1.5-2 dtex, and 15-20 parts of lyocell fiber with the length of 7-10 mm and the fineness of 1-2 dtex. The preparation method of the modified polylactic acid fiber comprises the following steps: carrying out ester exchange reaction on alkyl aminobenzoate and polylactic acid with the number-average molecular weight of 50,000-80,000 to obtain modified polylactic acid, reacting the modified polylactic acid with 2, 3-epoxypropyl trimethyl ammonium chloride to obtain quaternized polylactic acid, blending the quaternized polylactic acid and polylactic acid with the number-average molecular weight of 100,000-150,000, and carrying out melt spinning. Due to the introduction of the modified polylactic acid fiber side group, the crystallinity of polylactic acid is reduced, and the flexibility of the polylactic acid fiber and the softness of the spunlaced non-woven fabric are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-woven fabrics, and particularly relates to a spunlace non-woven fabric for biodegradable wet wipes and a preparation method thereof. Background Art

[0002] With the continuous improvement of people's living standards and the enhancement of health awareness, wet wipes, as a convenient and hygienic cleaning product, are increasingly widely used in daily life, covering multiple fields such as personal care, household cleaning, and healthcare. Spunlace non-woven fabrics have become an essential raw material for preparing wet wipes due to their good softness, water absorbency, strength, and hand feel.

[0003] Traditional spunlace non-woven fabrics for wet wipes mostly use non-biodegradable synthetic fibers such as polyester fibers and polypropylene fibers as raw materials. Although these materials perform well in terms of performance, they are difficult to degrade in the natural environment and remain for a long time after being discarded, causing serious "white pollution" to ecological environments such as soil and water bodies. With the continuous awakening of global environmental awareness and the increasingly strict environmental protection regulations, it is urgent to develop biodegradable spunlace non-woven fabrics for wet wipes.

[0004] A bacteriostatic and water-absorbent functional wet wipe disclosed in Patent CN108286125B is formed by hydroentangling and reinforcing multiple fiber webs including a carded fiber web, a modified hot-melt fiber web, a hot-rolled fiber web layer, and a water-absorbent fiber web. To reduce the environmental burden, its carded fiber web and water-absorbent fiber web are mostly prepared from degradable materials. However, the entanglement effect between the fiber webs of each layer is poor, resulting in insufficient strength of the wet wipe, easy breakage during use, and negative impacts on its bacteriostatic and water-absorbent properties. Patent CN112760810B discloses a biodegradable wet wipe production process, wet wipes, and a packaging film for the wet wipes. The raw materials include chitosan fibers, bamboo pulp fibers, etc. The mixed carding, cross-laying, and hydroentangling and drying technologies are adopted. The base fabric prepared not only overcomes the strength problem existing in the above patents but also saves the use of bacteriostatic agents and preservatives because the non-woven fabric itself has bacteriostatic functions. However, the softness of this biodegradable wet wipe still needs to be improved because the molecular chain of polylactic acid has high regularity and crystallinity, which makes it have a certain rigidity and is difficult to bend and deform easily like wood pulp fibers when subjected to external forces. During the hydroentangling process, wood pulp fibers will orderly aggregate and arrange around the rigid polylactic acid staple fibers to form a compact structure. Although this structure is beneficial to improving the strength of the non-woven fabric to a certain extent, it will reduce the softness of the non-woven fabric: it feels "hard" and "prickly" when touched, its texture is harder, and it is not soft and smooth enough, affecting the user experience.

[0005] Therefore, it is necessary to develop a non-woven fabric for biodegradable wet wipes that can meet both the strength requirements and softness requirements of consumers. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a spunlace nonwoven fabric for biodegradable wet wipes and a preparation method thereof. The raw materials of the spunlace nonwoven fabric include a modified polylactic acid fiber prepared by blending and melt spinning a quaternized polylactic acid with a quaternary ammonium salt side group in the molecular structure and polylactic acid. The introduction of the side group can disrupt the regularity and ordered arrangement of the polylactic acid molecular chain, weaken the intermolecular force between the molecular chains, reduce the crystallinity, improve the flexibility of the polylactic acid fiber, and improve the softness of the spunlace nonwoven fabric; the seaweed fiber synergistically modifies the polylactic acid fiber to improve the strength of the spunlace nonwoven fabric. At the same time, the seaweed fiber and the modified polylactic acid fiber in the raw materials act synergistically to further enhance the mechanical strength of the spunlace nonwoven fabric, enabling it to have good mechanical properties while maintaining excellent softness.

[0007] To achieve the above object, the following technical solutions are adopted:

[0008] A spunlace nonwoven fabric for biodegradable wet wipes, comprising the following raw materials in parts by weight: 40-50 parts of wood pulp fiber, 20-30 parts of modified polylactic acid fiber, 1-2.5 parts of seaweed fiber, and 15-20 parts of lyocell fiber;

[0009] The preparation steps of the modified polylactic acid fiber include:

[0010] 1) Carrying out an ester exchange reaction between an alkyl ester of aminobenzoic acid and polylactic acid with a number average molecular weight of 50,000-80,000 to obtain modified polylactic acid;

[0011] 2) Reacting the modified polylactic acid with 2,3-epoxypropyltrimethylammonium chloride to obtain quaternized polylactic acid;

[0012] 3) Blending the quaternized polylactic acid with polylactic acid having a number average molecular weight of 100,000-150,000 and melt spinning.

[0013] Quaternary ammonium salt side groups are introduced into the polymer molecular chain of the modified polylactic acid fiber. Since the quaternary ammonium salt side group carries a positive charge, the electrostatic repulsion between the molecular chains will hinder the ordered arrangement of the molecular chains and reduce the crystallinity. In addition, the steric hindrance effect of the quaternary ammonium salt side group will also limit the local movement of the polymer chain and interfere with the regular folding of the chain segments during the crystallization process, also reducing the crystallinity. Although the reduction of crystallinity helps to improve the softness of the spunlace nonwoven fabric, it will also have an adverse effect on its mechanical properties. The polylactic acid fiber in the spunlace nonwoven fabric contributes greatly to the mechanical properties. To make up for the loss of strength after modification, an appropriate amount of seaweed fiber needs to be added to the raw materials to ensure that the overall strength of the spunlace nonwoven fabric is not affected.

[0014] Seaweed fiber is a fiber made by spinning alginate, which is more flexible and deformable than polylactic acid fiber. An appropriate amount of seaweed fiber forms entanglements and overlaps with modified polylactic acid fiber during the hydroentangling process. Under the synergistic effect of seaweed fiber and modified polylactic acid fiber, the modified polylactic acid fiber can play its role in improving the softness of the hydroentangled nonwoven fabric without affecting the overall strength of the hydroentangled nonwoven fabric.

[0015] The mass ratio of the alkyl ester of aminobenzoic acid to polylactic acid with a number average molecular weight of 50,000 - 80,000 is 3 - 5:100; the mass ratio of 2,3-epoxypropyltrimethylammonium chloride to modified polylactic acid is 5 - 8:100; the mass ratio of quaternized polylactic acid to polylactic acid with a number average molecular weight of 100,000 - 150,000 is 10 - 15:100.

[0016] The alkyl ester of aminobenzoic acid is selected from one or a combination of two or more of dimethyl 2-aminoterephthalate, diethyl 2-aminoterephthalate, dimethyl 5-aminoisophthalate, diethyl 5-aminoisophthalate, dimethyl 4-aminoisophthalate, diethyl 4-aminoisophthalate, dimethyl 3-amino-phthalate, diethyl 3-amino-phthalate, and dimethyl 2-aminophthalate.

[0017] The modified polylactic acid fiber has a length of 12 - 15 mm and a fineness of 1 - 2 dtex; the seaweed fiber has a length of 30 - 40 mm and a fineness of 1.5 - 2 dtex; the Lyocell fiber has a length of 7 - 10 mm and a fineness of 1 - 2 dtex.

[0018] Specifically, the modified polylactic acid fiber is prepared by a method including the following steps:

[0019] 1) Dissolve polylactic acid with a number average molecular weight of 50,000 - 80,000 in an organic solvent, add the alkyl ester of aminobenzoic acid and a catalyst, and heat to the reflux state for reaction to obtain modified polylactic acid;

[0020] 2) Dissolve the modified polylactic acid in an organic solvent, add 2,3-epoxypropyltrimethylammonium chloride and mix evenly, and heat for reaction to obtain quaternized polylactic acid;

[0021] 3) Blend the quaternized polylactic acid and polylactic acid with a number average molecular weight of 100,000 - 150,000, and melt-spin to obtain the modified polylactic acid fiber.

[0022] In step 1), the organic solvent is selected from one or a combination of two or more of acetonitrile, chloroform, and 1,1,2-trichloroethane, preferably 1,1,2-trichloroethane. The catalyst is selected from one or a combination of two or more of tetrabutyl titanate, p-toluenesulfonic acid, and sodium formate. The dosage of the catalyst is 1-3 wt% of the sum of the masses of polylactic acid with a number-average molecular weight of 50,000-80,000 and alkyl p-aminobenzoate. The reaction time is 10-18 h. After the reaction, purification treatment is also included: adding an alkali solution, liquid separation, and vacuum distillation of the organic phase. The concentration of the alkali solution is 15-20 wt%, and the alkali solution is selected from one or a combination of two of sodium hydroxide solution and potassium hydroxide solution. The liquid separation is to remove the water layer. The vacuum distillation is to remove the solvent.

[0023] In step 2), the organic solvent is selected from one or a combination of two or more of acetonitrile, chloroform, and 1,1,2-trichloroethane, preferably acetonitrile. The temperature is raised to 60-80 °C, the reaction time is 3-8 h, and after the reaction, the solvent is removed by vacuum distillation.

[0024] In step 3), a circular spinneret hole is used for melt spinning. The process parameters of melt spinning are as follows: the spinning temperature is 225-255 °C, the winding speed is 1700-1800 m / min; the drawing temperature is 65-80 °C, and the drawing ratio is 2.8-3.2 times; the heat setting temperature is 100-120 °C, and the heat setting time is 1-3 minutes; the speed of the crimper is 2-2.5 m / s, the main pressure of the crimper wheel is 0.25-0.35 MPa, the back pressure of the crimper wheel is 0.06-0.1 MPa, the crimper temperature is 60-90 °C, and the number of crimps is 5-25; the cut length is 7-10 mm.

[0025] The wood pulp fiber has a length of 1-4 mm and a width of 40-55 μm, and is selected from one or a combination of two or more of softwood pulp fibers and hardwood pulp fibers.

[0026] The present invention also provides a method for preparing the hydroentangled nonwoven fabric for biodegradable wet wipes, comprising the following steps:

[0027] The wood pulp fiber, modified polylactic acid fiber, lyocell fiber, and seaweed fiber are respectively opened, mixed, carded, cross-laid, hydroentangled, dried, crimped, sterilized, and slit to obtain the hydroentangled nonwoven fabric for biodegradable wet wipes.

[0028] The hydroentanglement is carried out in a drum-type hydroentangling machine, and the drum-type hydroentangling machine includes 4-6 passes of hydroentanglement, the hydroentanglement pressure is 20-80 bar, and the diameter of the water needle holes of the hydroentangling heads is 0.1-0.3 mm.

[0029] The drying is carried out in a vacuum drying oven at 100-120 °C for 2-5 h.

[0030] The sterilization is carried out by ultraviolet irradiation.

[0031] The basis weight of the spunlace nonwoven fabric for the biodegradable wet wipes is 50 - 80 g / m 2 .

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] In the raw materials of the spunlace nonwoven fabric of the present invention, there is a modified polylactic acid fiber prepared by blending and melt spinning a quaternized polylactic acid containing a quaternary ammonium salt side group in the molecular structure with polylactic acid. The introduction of the side group can destroy the regularity and ordered arrangement of the polylactic acid molecular chain, weaken the intermolecular force, reduce the crystallinity, improve the flexibility of the polylactic acid fiber, and improve the softness of the spunlace nonwoven fabric.

[0034] In the raw materials of the present invention, the seaweed fiber and the modified polylactic acid fiber act synergistically to further enhance the mechanical strength of the spunlace nonwoven fabric, so that it has good mechanical properties while maintaining excellent softness. Specific Embodiments

[0035] The present invention will be further described below in conjunction with specific embodiments, but it is not limited to the content in the specification. Unless otherwise specified, the "parts" mentioned in the embodiments of the present invention are all parts by weight. The reagents used are all commercially available reagents in this field.

[0036] Polylactic acids with number average molecular weights of 50,000, 80,000, and 150,000 are all purchased from Hubei Langbowan Biomedical Co., Ltd.

[0037] Hardwood pulp fibers are purchased from Hangzhou Xiangfu Wood Pulp Fiber Manufacturing Co., Ltd., with a length of 2.2 mm and a width of 42.1 μm.

[0038] Lyocell fibers are purchased from Baoding Swan New Fiber Manufacturing Co., Ltd., with a length of 10 mm and a fineness of 1.7 dtex.

[0039] Seaweed fibers with a length of 38 mm and a fineness of 2 dtex and a length of 30 mm and a fineness of 1.5 dtex are all purchased from Shaoxing Dan'ao Textiles Co., Ltd.

[0040] Example 1

[0041] 1) Dissolve 100 kg of polylactic acid with a number average molecular weight of 50,000 in 200 L of 1,1,2 - trichloroethane, add 5 kg of dimethyl 5 - aminoterephthalate and 3 kg of p - toluenesulfonic acid, heat up to the reflux state and react for 12 h, add 20 wt% sodium hydroxide solution with a volume of 1 / 2 of the reaction mixture obtained, separate the liquid, and distill the organic phase under reduced pressure to remove impurities to obtain modified polylactic acid;

[0042] 2) 100 kg of modified polylactic acid was dissolved in 200 L of acetonitrile, 8 kg of 2,3-epoxypropyltrimethylammonium chloride was added and mixed evenly, the temperature was raised to 80 °C and reacted for 5 h, and the solvent was removed by vacuum distillation to obtain quaternized polylactic acid;

[0043] 3) 15 kg of quaternized polylactic acid and 100 kg of polylactic acid with a number-average molecular weight of 150,000 were blended, and melt spinning was carried out in a single-screw spinning machine using circular spinneret holes to obtain modified polylactic acid fibers. The melt spinning process parameters were as follows: the spinneret temperature was set at 235 °C (spinning temperature), the winding speed was 1800 m / min; the drawing temperature was 80 °C, and the drawing ratio was 2.8 times; the heat setting temperature was 100 °C, and the heat setting time was 3 minutes; the speed of the crimper was 2.5 m / s, the main pressure of the crimper wheel was 0.25 MPa, the back pressure of the crimper wheel was 0.06 MPa, the crimper temperature was 60 °C, and the number of crimps was 12; the cut length was 15 mm.

[0044] 4) 50 kg of hardwood pulp fibers, 30 kg of modified polylactic acid fibers, 20 kg of Lyocell fibers, and 2.5 kg of seaweed fibers with a length of 38 mm and a fineness of 2 dtex were respectively opened, mixed, carded, cross-laid, and hydroentangled in a drum hydroentangling machine successively with hydroentangling pressures of 20 bar, 40 bar, 45 bar, 60 bar, 50 bar, and 45 bar (the diameter of the water needle hole was 0.12 mm), dried in a vacuum drying oven at 120 °C for 3 h, crimped, sterilized by ultraviolet irradiation, and slit to obtain a hydroentangled nonwoven fabric for biodegradable wet wipes with a basis weight of 50 g / m 2 of.

[0045] Example 2

[0046] The rest was the same as in Example 1, except that in step 4), the amount of modified polylactic acid fibers used was 20 kg.

[0047] Example 3

[0048] The rest was the same as in Example 1, except that in step 4), the amount of seaweed fibers used was 1 kg.

[0049] Example 4

[0050] The rest was the same as in Example 1, except that in step 3), the amount of quaternized polylactic acid used was 10 kg.

[0051] Example 5

[0052] The rest was the same as in Example 1, except that in step 2), the amount of 2,3-epoxypropyltrimethylammonium chloride used was 5 kg.

[0053] Example 6

[0054] The rest is the same as in Example 1, except that in step 1), the amount of dimethyl 5-aminoterephthalate used is 3 kg.

[0055] Example 7

[0056] The rest is the same as in Example 1, except that in step 1), dimethyl 2-aminoterephthalate of equal mass is used to replace dimethyl 5-aminoterephthalate.

[0057] Example 8

[0058] The rest is the same as in Example 1, except that in step 4), the seaweed fiber has a specification of 30 mm in length and 1.5 dtex in fineness.

[0059] Example 9

[0060] 1) Dissolve 100 kg of polylactic acid with a number-average molecular weight of 50,000 in 200 L of 1,1,2-trichloroethane, add 3 kg of dimethyl 5-aminoterephthalate and 3 kg of p-toluenesulfonic acid, heat up to the reflux state and react for 12 h, add 20 wt% sodium hydroxide solution with a volume of 1 / 2 of the reaction mixture, separate the liquid, and distill the organic phase under reduced pressure to remove impurities to obtain modified polylactic acid;

[0061] 2) Dissolve 100 kg of modified polylactic acid in 200 L of acetonitrile, add 5 kg of 2,3-epoxypropyltrimethylammonium chloride and mix well, heat up to 80 °C and react for 5 h, and distill off the solvent under reduced pressure to obtain quaternized polylactic acid;

[0062] 3) Blend 15 kg of quaternized polylactic acid and 100 kg of polylactic acid with a number-average molecular weight of 150,000, and carry out melt spinning in a single-screw spinning machine using circular spinneret holes to obtain modified polylactic acid fibers. The melt spinning process parameters are as follows: the spinneret temperature is set at 235 °C (spinning temperature), the winding speed is 1800 m / min; the drawing temperature is 80 °C, and the drawing ratio is 2.8 times; the heat setting temperature is 100 °C, and the heat setting time is 3 minutes; the speed of the crimper is 2.5 m / s, the main pressure of the crimper wheel is 0.25 MPa, the back pressure of the crimper wheel is 0.06 MPa, the crimper temperature is 60 °C, and the number of crimps is 12; the cutting length is 12 mm.

[0063] 4) Open, mix, card, cross-lay, and water-jet reinforce in a drum-type hydroentangling machine with water-jet pressures of 20 bar, 40 bar, 45 bar, 60 bar, 50 bar, and 45 bar in sequence (the diameter of the water-jet holes is 0.12 mm) for 40 kg of hardwood pulp fibers, 20 kg of modified polylactic acid fibers, 30 kg of lyocell fibers, and 1 kg of seaweed fibers with a length of 30 mm and a fineness of 1.5 dtex, dry in a vacuum drying oven at 120 °C for 3 h, crimp, sterilize by ultraviolet irradiation, and slit to obtain a basis weight of 50 g / m2 Hydroentangled nonwoven fabric for biodegradable wet wipes.

[0064] Comparative Example 1

[0065] 1) 100 kg of polylactic acid with a number-average molecular weight of 150,000 was blended and melt-spun into polylactic acid fibers in a single-screw spinning machine using circular spinneret holes. The melt-spinning process parameters were as follows: the spinneret temperature was set at 235 °C (spinning temperature), the winding speed was 1800 m / min; the drawing temperature was 80 °C, and the drawing ratio was 2.8 times; the heat-setting temperature was 100 °C, and the heat-setting time was 3 minutes; the crimper speed was 2.5 m / s, the main pressure of the crimper wheel was 0.25 MPa, the back pressure of the crimper wheel was 0.06 MPa, the crimper temperature was 60 °C, and the number of crimps was 12; the cut length was 15 mm.

[0066] 2) 50 kg of broadleaf wood pulp fibers, 30 kg of polylactic acid fibers, 20 kg of lyocell fibers, and 2.5 kg of seaweed fibers with a length of 38 mm and a fineness of 2 dtex were respectively opened, mixed, carded, cross-laid, and hydroentangled in a drum hydroentangling machine successively with hydroentangling pressures of 20 bar, 40 bar, 45 bar, 60 bar, 50 bar, and 45 bar (the diameter of the water-jet holes was 0.12 mm), dried in a vacuum drying oven at 120 °C for 3 h, crimped, sterilized by ultraviolet irradiation, and slit to obtain a hydroentangled nonwoven fabric for biodegradable wet wipes with a basis weight of 50 g / m 2 Hydroentangled nonwoven fabric for biodegradable wet wipes.

[0067] Comparative Example 2

[0068] The rest was the same as in Example 1, except that in step 4), the amount of seaweed fibers was 0.5 kg.

[0069] Comparative Example 3

[0070] The rest was the same as in Example 1, except that in step 4), the amount of seaweed fibers was 3 kg.

[0071] Comparative Example 4

[0072] The rest was the same as in Example 1, except that in step 2), 1,2-epoxybutane of equal mass was used to replace 2,3-epoxypropyltrimethylammonium chloride.

[0073] The hydroentangled nonwoven fabrics prepared in the above examples and comparative examples were subjected to the following performance tests:

[0074] Tensile strength: Referring to the standard GB / T 24218.3-2010 "Textiles - Test methods for nonwovens - Part 3: Determination of breaking force and elongation at break", the transverse tensile strength of the composite material in the wet state was tested using a YG028-500 type tensile tester. The specimen size was 50mm * 500mm, the clamping distance was 200mm, and the tensile speed was 100mm / min.

[0075] Antibacterial property: Referring to the standard GB / T 15979-2024 "Hygienic requirements for disposable sanitary products", the bactericidal rate of the spunlace nonwoven fabric of the present invention was tested. The action time was 5 min, Escherichia coli was used as the test strain, and the bactericidal rate was evaluated according to the following standards: Grade A bactericidal rate ≥ 95%; Grade B 95% > bactericidal rate ≥ 90%; Grade C bactericidal rate < 90%.

[0076] Bending length: The test was carried out referring to the standard GB / T 18318.1-2009 "Textiles - Determination of bending properties". The bending length refers to the length of a rectangular fabric specimen with one end held and the other end suspended when it bends to 7.1° under its own weight. The smaller the bending length, the easier it is to bend and deform under its own weight, which means it is softer.

[0077] Table 1 Performance test results

[0078] Project Transverse fracture strength N Antibacterial grade level Transverse bending length cm Example 1 13.6 A 0.7 Example 2 14.2 B 1.2 Example 3 12.7 B 1.0 Example 4 13.9 B 0.8 Example 5 13.8 B 0.8 Example 6 13.8 B 1.0 Example 7 13.6 A 0.7 Example 8 13.1 A 0.7 Example 9 12.7 B 1.5 Comparative example 1 12.5 C 1.9 Comparative example 2 12.8 C 2.5 Comparative example 3 14.9 A 3.2 Comparative example 4 12.0 C 2.1

[0079] It can be seen from the performance test results in Table 1 that the nonwoven fabric prepared by the present invention has excellent antibacterial properties and can obtain excellent softness without affecting the overall strength.

[0080] The above detailed description is a specific description of one feasible embodiment of the present invention. This embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification without departing from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A spunlace nonwoven fabric for biodegradable wet wipes, characterized in that, It comprises the following raw materials in parts by weight: 40-50 parts of wood pulp fiber, 20-30 parts of modified polylactic acid fiber, 1-2.5 parts of seaweed fiber, and 15-20 parts of Lyocell fiber; The preparation steps of the modified polylactic acid fiber include: 1) Transesterification reaction is carried out between alkyl p-aminobenzoate and polylactic acid with a number average molecular weight of 50,000-80,000 to obtain modified polylactic acid; 2) The modified polylactic acid reacts with 2,3-epoxypropyltrimethylammonium chloride to obtain quaternized polylactic acid; 3) The quaternized polylactic acid is blended with polylactic acid with a number average molecular weight of 100,000-150,000 and melt-spun.

2. The spunlace nonwoven fabric for biodegradable wet wipes according to claim 1, characterized in that, The mass ratio of the alkyl p-aminobenzoate to the polylactic acid with a number average molecular weight of 50,000-80,000 is 3-5:100; the mass ratio of the 2,3-epoxypropyltrimethylammonium chloride to the modified polylactic acid is 5-8:100; the mass ratio of the quaternized polylactic acid to the polylactic acid with a number average molecular weight of 100,000-150,000 is 10-15:

100.

3. The hydroentangled nonwoven fabric for biodegradable wet wipes according to claim 1, characterized in that, The alkyl p-aminobenzoate is selected from one or a combination of two or more of dimethyl 2-aminoterephthalate, diethyl 2-aminoterephthalate, dimethyl 5-aminoisophthalate, diethyl 5-aminoisophthalate, dimethyl 4-aminoisophthalate, diethyl 4-aminoisophthalate, dimethyl 3-amino-phthalate, diethyl 3-amino-phthalate, and dimethyl 2-aminophthalate.

4. The hydroentangled nonwoven fabric for biodegradable wet wipes according to claim 1, characterized in that The modified polylactic acid fiber has a length of 12-15 mm and a fineness of 1-2 dtex; the seaweed fiber has a length of 30-40 mm and a fineness of 1.5-2 dtex; the Lyocell fiber has a length of 7-10 mm and a fineness of 1-2 dtex.

5. The hydroentangled nonwoven fabric for biodegradable wet wipes according to claim 1, wherein The modified polylactic acid fiber is prepared by a method including the following steps: 1) Dissolve polylactic acid with a number average molecular weight of 50,000-80,000 in an organic solvent, add alkyl p-aminobenzoate and a catalyst, and heat to the reflux state for reaction to obtain modified polylactic acid; 2) Dissolve the modified polylactic acid in an organic solvent, add 2,3-epoxypropyltrimethylammonium chloride and mix evenly, and heat for reaction to obtain quaternized polylactic acid; 3) Blend the quaternized polylactic acid with polylactic acid with a number average molecular weight of 100,000-150,000, and melt-spin to obtain the modified polylactic acid fiber.

6. The spunlace nonwoven fabric for biodegradable wet wipes according to claim 5, wherein, In step 1), the catalyst is selected from one or a combination of two or more of tetrabutyl titanate, p-toluenesulfonic acid, and sodium formate; the dosage of the catalyst is 1-3 wt% of the sum of the masses of the polylactic acid with a number average molecular weight of 50,000-80,000 and the alkyl p-aminobenzoate.

7. The hydroentangled nonwoven fabric for biodegradable wet wipes according to claim 5, characterized in that, In step 2), the organic solvent is selected from one or a combination of two or more of acetonitrile, chloroform, and 1,1,2-trichloroethane, preferably acetonitrile; the heating is to 60-80 °C, the reaction time is 3-8 h, and the solvent is removed by vacuum distillation after the reaction ends.

8. The spunlace nonwoven fabric for biodegradable wet wipes according to claim 1, wherein In step 3), the melt spinning process parameters are as follows: the spinning temperature is 225 - 255 °C, the winding speed is 1700 - 1800 m / min; the drawing temperature is 65 - 80 °C, and the drawing ratio is 2.8 - 3.2 times; the heat setting temperature is 100 - 120 °C, and the heat setting time is 1 - 3 minutes; the speed of the crimper is 2 - 2.5 m / s, the main pressure of the crimper wheel is 0.25 - 0.35 MPa, the back pressure of the crimper wheel is 0.06 - 0.1 MPa, the crimper temperature is 60 - 90 °C, the number of crimps is 5 - 25; the cut length is 7 - 10 mm.

9. The hydroentangled nonwoven fabric for biodegradable wet wipes according to claim 1, wherein The wood pulp fiber has a length of 1 - 4 mm and a width of 40 - 55 μm, and is selected from one or more combinations of softwood pulp fibers and hardwood pulp fibers.

10. The preparation method of the spunlace nonwoven fabric for biodegradable wet wipes according to any one of claims 1-9, characterized in that, It includes the following steps: Open, mix, card, cross-lay, hydroentangle, dry, crimp, sterilize, and slit the wood pulp fiber, modified polylactic acid fiber, lyocell fiber, and seaweed fiber respectively to obtain a hydroentangled nonwoven fabric for biodegradable wet wipes.