A hot air preparation method for high-permeability and high-strength polylactic acid composite non-woven fabric

Abstract

The present invention discloses a hot air preparation method for a highly breathable and high-strength polylactic acid composite non-woven fabric, which belongs to the technical field of polylactic acid material preparation. The method comprises: stirring and dissolving polylactic acid in dimethylformamide, adding potassium persulfate and sodium bisulfite; adding ethyl acrylate and butyl acrylate, and adding thioglycolic acid for reaction; adding trimethylolpropane triacrylate, adding triethylamine, and continuing the reaction; separating to obtain grafted polylactic acid; dissolving the grafted polylactic acid in acetone, adding tetraethylammonium bromide for dissolution, slowly adding a dilute sulfuric acid solution dropwise, and reacting; cooling and separating to obtain modified polylactic acid; mixing the modified polylactic acid, polycaprolactone, and an auxiliary agent, melt-spinning into fibers, weaving, laying a net, and needle-punching; and hot air combing. The present invention adopts a specific modification reagent and method to prepare modified polylactic acid fibers, and adopts the modified polylactic acid fibers in combination with specific hot air non-woven fabric preparation steps and parameters to prepare highly breathable and high-strength polylactic acid composite non-woven fabrics.

Description

Technical Field

[0001] The invention belongs to the technical field of polylactic acid material preparation, and particularly relates to a hot air preparation method for a high-permeability and high-strength polylactic acid composite non-woven fabric. Background Art

[0002] With growing environmental awareness, the application of biodegradable materials in various fields has become increasingly important. Polylactic acid (PLA), a biodegradable material extracted from renewable plant resources, is an ideal alternative to traditional plastics due to its environmental friendliness, biocompatibility, and processability. In the textile industry, nonwoven fabrics made from PLA fibers have attracted considerable attention due to their unique properties.

[0003] The hot-air method for producing polylactic acid composite nonwovens primarily utilizes carded polylactic acid fibers with a specific structure to form a web. This web is then reinforced through hot-air setting, resulting in an environmentally friendly nonwoven fabric. The advantages of this method lie in its environmentally friendly production process, biodegradability, and excellent physical properties. Hot-air setting not only enhances the strength of the nonwoven fabric but also maintains its excellent air permeability and moisture absorption, enabling it to excel in a variety of applications.

[0004] However, some PLA nonwovens currently on the market still suffer from technical drawbacks, particularly in achieving a balance between breathability and strength. Traditional nonwoven fabric production processes can result in uneven fiber distribution, which in turn affects the fabric's breathability. Furthermore, excessive heat-pressing to improve strength can also reduce the fabric's breathability, potentially causing discomfort to users during use.

[0005] Polylactic acid composite nonwovens, through their unique fiber structure and hot-air setting technology, promise to address this issue. The specific fiber arrangement and the temperature and pressure control during the hot-air setting process are key factors influencing the nonwoven's breathability and strength. Precise control of these parameters can achieve a balance between breathability and strength, resulting in environmentally friendly, high-performance nonwovens.

[0006] With consumers' increasing demands for environmental protection and health, the market for polylactic acid composite nonwovens is promising. Not only are they widely used in healthcare, personal care, and other fields, they are also expected to replace traditional non-degradable nonwovens, contributing to the green development of the textile industry. Furthermore, with further research and optimization of preparation technologies, the performance of polylactic acid composite nonwovens will be further enhanced to meet more diverse market demands.

[0007] As an environmentally friendly and high-performance nonwoven production technology, the hot air method for preparing polylactic acid composite nonwovens offers significant advantages and broad development prospects. Although some technical challenges remain, these are expected to be overcome through continued research and development and innovation, promoting the wider application of polylactic acid nonwovens in various fields. Summary of the Invention

[0008] To solve the above problems, the present invention mainly optimizes from the perspective of fiber modification and provides a hot air preparation method for high-permeability and high-strength polylactic acid composite non-woven fabric. The specific scheme is as follows:

[0009] A hot air preparation method for a high-permeability and high-strength polylactic acid composite non-woven fabric comprises the following steps:

[0010] S1. Dissolve polylactic acid in dimethylformamide with stirring, and add potassium persulfate and sodium bisulfite and mix well;

[0011] S2. Maintaining the reaction temperature and continuing stirring, under nitrogen protection, slowly add ethyl acrylate and butyl acrylate at the same time, gradually add thioglycolic acid, and continue the reaction;

[0012] S3, after adding trimethylolpropane triacrylate, add triethylamine and continue the reaction;

[0013] S4, after the reaction is completed, the grafted polylactic acid is separated;

[0014] S5, dissolving the obtained grafted polylactic acid in acetone with stirring, adding tetraethylammonium bromide to dissolve, slowly adding dilute sulfuric acid solution dropwise, heating and stirring to react;

[0015] S6. After the reaction is completed, cooling and separation are performed to obtain modified polylactic acid;

[0016] S7, taking the obtained modified polylactic acid, polycaprolactone, and additives and mixing them to obtain a spinning material;

[0017] S8, adding the obtained spinning material into a screw extruder to melt, spinning, winding, drawing, and drying to obtain fibers;

[0018] S9, laying the obtained fibers through a swinging yarn, and subjecting the obtained fiber web to a hot air treatment to shape it into a cloth, thereby obtaining a polylactic acid composite non-woven fabric.

[0019] Preferably, in S8, the melting temperature is 180-200°C, the spinning temperature is 190-230°C, the winding speed is 800-1000 m / min, the drawing temperature is 70-90°C, and the draw ratio is 2.2-3.5 times.

[0020] Preferably, the tow spacing of the swing wire in S8 is 5-8 mm, the tow tension is 1.5-2.5 cN; the laying speed of the web is 20-50 m / min, the laying angle is 50-80°, excluding 60°, and the number of laying layers is 5-10 layers.

[0021] Preferably, in S9, the hot air temperature is 100-130° C., the hot air speed is 4-8 m / s, and the hot air combing time is 30-50 s.

[0022] Preferably, the stirring and dissolving in S1 is carried out at 70-75°C.

[0023] Preferably, the concentration of polylactic acid in dimethylformamide in S1 is 0.3-0.5 g / mL.

[0024] Preferably, the mass ratio of polylactic acid, potassium persulfate and sodium bisulfite in S1 is (10-15):(0.04-0.08):(0.03-0.06).

[0025] Preferably, the reaction temperature in S2 is maintained at 80-85°C.

[0026] Preferably, in S2, the ratio of ethyl acrylate to polylactic acid is 0.15-0.3 mL of ethyl acrylate per 1 g of polylactic acid; and the ratio of butyl acrylate to polylactic acid is 0.05-0.1 mL of butyl acrylate per 1 g of polylactic acid.

[0027] Preferably, the mass ratio of thioglycolic acid to polylactic acid in S2 is (0.0015-0.0025):1.

[0028] Preferably, the usage ratio of trimethylolpropane triacrylate to polylactic acid in S3 is 0.02-0.04 mL of trimethylolpropane triacrylate per 1 g of polylactic acid; and the usage mass ratio of triethylamine to polylactic acid is (0.0025-0.004):1.

[0029] Preferably, the amount of acetone in S5 is 5-10 times the mass of the grafted polylactic acid.

[0030] Preferably, the mass ratio of tetraethylammonium bromide to grafted polylactic acid in S5 is (0.01-0.05):1.

[0031] Preferably, the concentration of the dilute sulfuric acid solution in S5 is 0.5-1.5 mol / L; and the amount used is 15-25 vol% of the volume of acetone.

[0032] Preferably, the heating and stirring reaction in S5 is carried out at a temperature of 50-70° C. and for 3-7 hours.

[0033] Preferably, the amount of polycaprolactone in S7 is 10-12 wt % of the modified polylactic acid.

[0034] Preferably, the auxiliary agent in S7 includes 2-5 wt% of phthalate in the modified polylactic acid and 0.1-0.5 wt% of calcium stearate in the modified polylactic acid.

[0035] Beneficial effects

[0036] The invention adopts a specific modifying agent and method to prepare modified polylactic acid fiber, and adopts the modified polylactic acid fiber in combination with specific hot air non-woven fabric preparation steps and parameters to prepare a high-permeability and high-strength polylactic acid composite non-woven fabric. DETAILED DESCRIPTION

[0037] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods and materials similar or equivalent to those described herein can be applied to the present invention. The preferred embodiments and materials described herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0039] Unless otherwise specified, the experimental methods in the following examples are all conventional methods, and the experimental materials used in the following examples are all purchased from commercial channels unless otherwise specified.

[0040] Polylactic acid particles: NatureWorks 4032D PLA, molecular weight 150,000 g / mol;

[0041] Dimethylformamide: N,N-dimethylformamide, Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 68-12-2;

[0042] Potassium persulfate: Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0043] Sodium bisulfite: Beekman Biotechnology, CAS No. 7757-83-7;

[0044] Ethyl acrylate: Nanjing Chemical Reagent Co., Ltd., 98%;

[0045] Butyl acrylate: Xilong Science, 1 mol / L;

[0046] Thioglycolic acid: ammonium thioglycolate, Jiangsu Xinsu New Materials Co., Ltd.;

[0047] Trimethylolpropane triacrylate: Shandong West Asia Chemical Co., Ltd., 85%;

[0048] Triethylamine: Hubei Weishi Chemical Reagent Co., Ltd.

[0049] Tetraethylammonium bromide: Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0050] Polycaprolactone: Shanghai Puzhen Biotechnology Co., Ltd.;

[0051] Phthalate: dimethyl phthalate, Hubei Chengfeng Chemical Co., Ltd.;

[0052] Calcium stearate: Guangzhou Hewei Pharmaceutical Technology Co., Ltd.

[0053] Example 1: A hot air preparation method for a high-permeability and high-strength polylactic acid composite non-woven fabric:

[0054] S1. Dissolve polylactic acid in dimethylformamide with stirring, and add potassium persulfate and sodium bisulfite and mix well;

[0055] S2. Maintaining the reaction temperature and continuing stirring, under nitrogen protection, slowly add ethyl acrylate and butyl acrylate at the same time, gradually add thioglycolic acid, and continue the reaction;

[0056] S3, after adding trimethylolpropane triacrylate, add triethylamine and continue the reaction;

[0057] S4, after the reaction is completed, the grafted polylactic acid is separated;

[0058] S5, dissolving the obtained grafted polylactic acid in acetone with stirring, adding tetraethylammonium bromide to dissolve, slowly adding dilute sulfuric acid solution dropwise, heating and stirring to react;

[0059] S6. After the reaction is completed, cooling and separation are performed to obtain modified polylactic acid;

[0060] S7, taking the obtained modified polylactic acid, polycaprolactone, and additives and mixing them to obtain a spinning material;

[0061] S8, adding the obtained spinning material into a screw extruder to melt, spinning, winding, drawing, and drying to obtain fibers;

[0062] S9, laying the obtained fibers through a swinging yarn, and subjecting the obtained fiber web to a hot air treatment to shape it into a cloth, thereby obtaining a polylactic acid composite non-woven fabric.

[0063] In S8, the melting temperature is 180°C, the spinning temperature is 190°C, the winding speed is 800 m / min, the drawing temperature is 70°C, and the multiple is 2.2 times.

[0064] The tow spacing of the swing wire in S8 is 5 mm, and the tow tension is 1.5 cN; the laying speed of the web is 20 m / min, the laying angle is 50°, and the number of laying layers is 5.

[0065] In S9, the hot air temperature is 100°C, the hot air speed is 4m / s, and the hot air combing time is 30s.

[0066] The stirring and dissolution in S1 is carried out at 70°C.

[0067] The concentration of polylactic acid in dimethylformamide in S1 was 0.3 g / mL.

[0068] The mass ratio of polylactic acid, potassium persulfate and sodium bisulfite in S1 is 10:0.08:0.06.

[0069] The reaction temperature was maintained at 80°C in S2.

[0070] In S2, the ratio of ethyl acrylate to polylactic acid is 0.15 mL of ethyl acrylate per 1 g of polylactic acid; the ratio of butyl acrylate to polylactic acid is 0.05 mL of butyl acrylate per 1 g of polylactic acid.

[0071] The mass ratio of thioglycolic acid to polylactic acid in S2 is 0.0015:1.

[0072] The usage ratio of trimethylolpropane triacrylate to polylactic acid in S3 is 0.02 mL of trimethylolpropane triacrylate per 1 g of polylactic acid; the usage mass ratio of triethylamine to polylactic acid is 0.0025:1.

[0073] The amount of acetone in S5 is 10 times the mass of the grafted polylactic acid.

[0074] The mass ratio of tetraethylammonium bromide to grafted polylactic acid in S5 is 0.01:1.

[0075] The concentration of the dilute sulfuric acid solution in S5 is 0.5 mol / L; the amount used is 15 vol% of the volume of acetone.

[0076] The heating and stirring reaction in S5 is carried out at a temperature of 50° C. for 3 hours.

[0077] The amount of polycaprolactone in S7 is 10 wt % of the modified polylactic acid.

[0078] The auxiliary agents in S7 include 2 wt% of phthalate modified polylactic acid and 0.2 wt% of calcium stearate modified polylactic acid.

[0079] Example 2: A hot air preparation method for a high-permeability and high-strength polylactic acid composite non-woven fabric:

[0080] S1. Dissolve polylactic acid in dimethylformamide with stirring, and add potassium persulfate and sodium bisulfite and mix well;

[0081] S2. Maintaining the reaction temperature and continuing stirring, under nitrogen protection, slowly add ethyl acrylate and butyl acrylate at the same time, gradually add thioglycolic acid, and continue the reaction;

[0082] S3, after adding trimethylolpropane triacrylate, add triethylamine and continue the reaction;

[0083] S4, after the reaction is completed, the grafted polylactic acid is separated;

[0084] S5, dissolving the obtained grafted polylactic acid in acetone with stirring, adding tetraethylammonium bromide to dissolve, slowly adding dilute sulfuric acid solution dropwise, heating and stirring to react;

[0085] S6. After the reaction is completed, cooling and separation are performed to obtain modified polylactic acid;

[0086] S7, taking the obtained modified polylactic acid, polycaprolactone, and additives and mixing them to obtain a spinning material;

[0087] S8, adding the obtained spinning material into a screw extruder to melt, spinning, winding, drawing, and drying to obtain fibers;

[0088] S9, laying the obtained fibers through a swinging yarn, and subjecting the obtained fiber web to a hot air treatment to shape it into a cloth, thereby obtaining a polylactic acid composite non-woven fabric.

[0089] In S8, the melting temperature is 180°C, the spinning temperature is 190°C, the winding speed is 800 m / min, the drawing temperature is 70°C, and the multiple is 2.2 times.

[0090] The tow spacing of the swing wire in S8 is 5 mm, and the tow tension is 1.5 cN; the laying speed of the web is 20 m / min, the laying angle is 50°, and the number of laying layers is 5.

[0091] In S9, the hot air temperature is 100°C, the hot air speed is 4m / s, and the hot air combing time is 30s.

[0092] The stirring and dissolving in S1 is carried out at 75°C.

[0093] The concentration of polylactic acid in dimethylformamide in S1 was 0.5 g / mL.

[0094] The mass ratio of polylactic acid, potassium persulfate and sodium bisulfite in S1 is 15:0.04:0.03.

[0095] The reaction temperature was maintained at 85°C in S2.

[0096] In S2, the ratio of ethyl acrylate to polylactic acid is 0.3 mL of ethyl acrylate per 1 g of polylactic acid; the ratio of butyl acrylate to polylactic acid is 0.1 mL of butyl acrylate per 1 g of polylactic acid.

[0097] The mass ratio of thioglycolic acid to polylactic acid in S2 is 0.0025:1.

[0098] The usage ratio of trimethylolpropane triacrylate to polylactic acid in S3 is 0.04 mL of trimethylolpropane triacrylate per 1 g of polylactic acid; the usage mass ratio of triethylamine to polylactic acid is 0.004:1.

[0099] The amount of acetone in S5 is 10 times the mass of the grafted polylactic acid.

[0100] The mass ratio of tetraethylammonium bromide to grafted polylactic acid in S5 is 0.05:1.

[0101] The concentration of the dilute sulfuric acid solution in S5 is 0.5 mol / L; the amount used is 15 vol% of the volume of acetone.

[0102] The heating and stirring reaction in S5 is carried out at a temperature of 70° C. for 7 hours.

[0103] The amount of polycaprolactone in S7 is 10 wt % of the modified polylactic acid.

[0104] The auxiliary agents in S7 include 2 wt% of phthalate modified polylactic acid and 0.2 wt% of calcium stearate modified polylactic acid.

[0105] Example 3: A hot air preparation method for a high-permeability and high-strength polylactic acid composite non-woven fabric:

[0106] S1. Dissolve polylactic acid in dimethylformamide with stirring, and add potassium persulfate and sodium bisulfite and mix well;

[0107] S2. Maintaining the reaction temperature and continuing stirring, under nitrogen protection, slowly add ethyl acrylate and butyl acrylate at the same time, gradually add thioglycolic acid, and continue the reaction;

[0108] S3, after adding trimethylolpropane triacrylate, add triethylamine and continue the reaction;

[0109] S4, after the reaction is completed, the grafted polylactic acid is separated;

[0110] S5, dissolving the obtained grafted polylactic acid in acetone with stirring, adding tetraethylammonium bromide to dissolve, slowly adding dilute sulfuric acid solution dropwise, heating and stirring to react;

[0111] S6. After the reaction is completed, cooling and separation are performed to obtain modified polylactic acid;

[0112] S7, taking the obtained modified polylactic acid, polycaprolactone, and additives and mixing them to obtain a spinning material;

[0113] S8, adding the obtained spinning material into a screw extruder to melt, spinning, winding, drawing, and drying to obtain fibers;

[0114] S9, laying the obtained fibers through a swinging yarn, and subjecting the obtained fiber web to a hot air treatment to shape it into a cloth, thereby obtaining a polylactic acid composite non-woven fabric.

[0115] In S8, the melting temperature is 180°C, the spinning temperature is 190°C, the winding speed is 800 m / min, the drawing temperature is 70°C, and the multiple is 2.2 times.

[0116] The tow spacing of the swing wire in S8 is 5 mm, and the tow tension is 1.5 cN; the laying speed of the web is 20 m / min, the laying angle is 50°, and the number of laying layers is 5.

[0117] In S9, the hot air temperature is 100°C, the hot air speed is 4m / s, and the hot air combing time is 30s.

[0118] The stirring and dissolution in S1 is carried out at 70°C.

[0119] The concentration of polylactic acid in dimethylformamide in S1 was 0.4 g / mL.

[0120] The mass ratio of polylactic acid, potassium persulfate and sodium bisulfite in S1 is 10:0.04:0.03.

[0121] The reaction temperature was maintained at 80°C in S2.

[0122] In S2, the ratio of ethyl acrylate to polylactic acid is 0.2 mL of ethyl acrylate per 1 g of polylactic acid; the ratio of butyl acrylate to polylactic acid is 0.08 mL of butyl acrylate per 1 g of polylactic acid.

[0123] The mass ratio of thioglycolic acid to polylactic acid in S2 is 0.0020:1.

[0124] The usage ratio of trimethylolpropane triacrylate to polylactic acid in S3 is 0.03 mL of trimethylolpropane triacrylate per 1 g of polylactic acid; the usage mass ratio of triethylamine to polylactic acid is 0.0030:1.

[0125] The amount of acetone in S5 is 10 times the mass of the grafted polylactic acid.

[0126] The mass ratio of tetraethylammonium bromide to grafted polylactic acid in S5 is 0.03:1.

[0127] The concentration of the dilute sulfuric acid solution in S5 is 0.5 mol / L; the amount used is 15 vol% of the volume of acetone.

[0128] The heating and stirring reaction in S5 is carried out at a temperature of 70° C. for 3 hours.

[0129] The amount of polycaprolactone in S7 is 10 wt % of the modified polylactic acid.

[0130] The auxiliary agents in S7 include 2 wt% of phthalate modified polylactic acid and 0.2 wt% of calcium stearate modified polylactic acid.

[0131] Example 4: A hot air preparation method for a high-permeability and high-strength polylactic acid composite non-woven fabric:

[0132] S1. Dissolve polylactic acid in dimethylformamide with stirring, and add potassium persulfate and sodium bisulfite and mix well;

[0133] S2. Maintaining the reaction temperature and continuing stirring, under nitrogen protection, slowly add ethyl acrylate and butyl acrylate at the same time, gradually add thioglycolic acid, and continue the reaction;

[0134] S3, after adding trimethylolpropane triacrylate, add triethylamine and continue the reaction;

[0135] S4, after the reaction is completed, the grafted polylactic acid is separated;

[0136] S5, dissolving the obtained grafted polylactic acid in acetone with stirring, adding tetraethylammonium bromide to dissolve, slowly adding dilute sulfuric acid solution dropwise, heating and stirring to react;

[0137] S6. After the reaction is completed, cooling and separation are performed to obtain modified polylactic acid;

[0138] S7, taking the obtained modified polylactic acid, polycaprolactone, and additives and mixing them to obtain a spinning material;

[0139] S8, adding the obtained spinning material into a screw extruder to melt, spinning, winding, drawing, and drying to obtain fibers;

[0140] S9, laying the obtained fibers through a swinging yarn, and subjecting the obtained fiber web to a hot air treatment to shape it into a cloth, thereby obtaining a polylactic acid composite non-woven fabric.

[0141] In S8, the melting temperature is 180°C, the spinning temperature is 190°C, the winding speed is 800 m / min, the drawing temperature is 70°C, and the multiple is 2.2 times.

[0142] The tow spacing of the swing wire in S8 is 5 mm, and the tow tension is 1.5 cN; the laying speed of the web is 20 m / min, the laying angle is 50°, and the number of laying layers is 5.

[0143] In S9, the hot air temperature is 100°C, the hot air speed is 4m / s, and the hot air combing time is 30s.

[0144] The stirring and dissolution in S1 is carried out at 70°C.

[0145] The concentration of polylactic acid in dimethylformamide in S1 was 0.4 g / mL.

[0146] The mass ratio of polylactic acid, potassium persulfate and sodium bisulfite in S1 is 10:0.04:0.03.

[0147] The reaction temperature was maintained at 80°C in S2.

[0148] In S2, the ratio of ethyl acrylate to polylactic acid is 0.2 mL of ethyl acrylate per 1 g of polylactic acid; the ratio of butyl acrylate to polylactic acid is 0.08 mL of butyl acrylate per 1 g of polylactic acid.

[0149] The mass ratio of thioglycolic acid to polylactic acid in S2 is 0.0020:1.

[0150] The usage ratio of trimethylolpropane triacrylate to polylactic acid in S3 is 0.03 mL of trimethylolpropane triacrylate per 1 g of polylactic acid; the usage mass ratio of triethylamine to polylactic acid is 0.0030:1.

[0151] The amount of acetone in S5 is 10 times the mass of the grafted polylactic acid.

[0152] The mass ratio of tetraethylammonium bromide to grafted polylactic acid in S5 is 0.03:1.

[0153] The concentration of the dilute sulfuric acid solution in S5 is 0.5 mol / L; the amount used is 15 vol% of the volume of acetone.

[0154] The heating and stirring reaction in S5 is carried out at a temperature of 70° C. for 3 hours.

[0155] The amount of polycaprolactone in S7 is 12 wt % of the modified polylactic acid.

[0156] The auxiliary agents in S7 include 2 wt% of phthalate modified polylactic acid and 0.2 wt% of calcium stearate modified polylactic acid.

[0157] Comparative Example 1: A hot air preparation method for a polylactic acid composite non-woven fabric (polylactic acid is not modified):

[0158] S1, taking polylactic acid, polycaprolactone, and an additive and mixing them to obtain a spinning material;

[0159] S2, adding the obtained spinning material into a screw extruder to melt, spinning, winding, drawing, and drying to obtain fibers;

[0160] S3, laying the obtained fibers through a swinging yarn, and subjecting the obtained fiber web to a hot air treatment to shape it into a cloth, thereby obtaining a polylactic acid composite non-woven fabric.

[0161] In S2, the melting temperature is 180°C, the spinning temperature is 190°C, the winding speed is 800 m / min, the drawing temperature is 70°C, and the multiple is 2.2 times.

[0162] The tow spacing of the swing wire in S2 is 5 mm, and the tow tension is 1.5 cN; the laying speed of the web is 20 m / min, the laying angle is 50°, and the number of laying layers is 5.

[0163] In S3, the hot air temperature is 100°C, the hot air speed is 4 m / s, and the hot air combing time is 30 s.

[0164] The amount of polycaprolactone in S1 is 12 wt % of the modified polylactic acid.

[0165] The auxiliary agents in S1 include phthalate containing 2 wt% of polylactic acid and calcium stearate containing 0.2 wt% of polylactic acid.

[0166] Comparative Example 2: A hot air preparation method for polylactic acid composite non-woven fabric (without adding polycaprolactone):

[0167] S1. Dissolve polylactic acid in dimethylformamide with stirring, and add potassium persulfate and sodium bisulfite and mix well;

[0168] S2. Maintaining the reaction temperature and continuing stirring, under nitrogen protection, slowly add ethyl acrylate and butyl acrylate at the same time, gradually add thioglycolic acid, and continue the reaction;

[0169] S3, after adding trimethylolpropane triacrylate, add triethylamine and continue the reaction;

[0170] S4, after the reaction is completed, the grafted polylactic acid is separated;

[0171] S5, dissolving the obtained grafted polylactic acid in acetone with stirring, adding tetraethylammonium bromide to dissolve, slowly adding dilute sulfuric acid solution dropwise, heating and stirring to react;

[0172] S6. After the reaction is completed, cooling and separation are performed to obtain modified polylactic acid;

[0173] S7, taking the obtained modified polylactic acid and an additive and mixing them to obtain a spinning material;

[0174] S8, adding the obtained spinning material into a screw extruder to melt, spinning, winding, drawing, and drying to obtain fibers;

[0175] S9, laying the obtained fibers through a swinging yarn, and subjecting the obtained fiber web to a hot air treatment to shape it into a cloth, thereby obtaining a polylactic acid composite non-woven fabric.

[0176] In S8, the melting temperature is 180°C, the spinning temperature is 190°C, the winding speed is 800 m / min, the drawing temperature is 70°C, and the multiple is 2.2 times.

[0177] The tow spacing of the swing wire in S8 is 5 mm, and the tow tension is 1.5 cN; the laying speed of the web is 20 m / min, the laying angle is 50°, and the number of laying layers is 5.

[0178] In S9, the hot air temperature is 100°C, the hot air speed is 4m / s, and the hot air combing time is 30s.

[0179] The stirring and dissolution in S1 is carried out at 70°C.

[0180] The concentration of polylactic acid in dimethylformamide in S1 was 0.4 g / mL.

[0181] The mass ratio of polylactic acid, potassium persulfate and sodium bisulfite in S1 is 10:0.04:0.03.

[0182] The reaction temperature was maintained at 80°C in S2.

[0183] In S2, the ratio of ethyl acrylate to polylactic acid is 0.2 mL of ethyl acrylate per 1 g of polylactic acid; the ratio of butyl acrylate to polylactic acid is 0.08 mL of butyl acrylate per 1 g of polylactic acid.

[0184] The mass ratio of thioglycolic acid to polylactic acid in S2 is 0.0020:1.

[0185] The usage ratio of trimethylolpropane triacrylate to polylactic acid in S3 is 0.03 mL of trimethylolpropane triacrylate per 1 g of polylactic acid; the usage mass ratio of triethylamine to polylactic acid is 0.0030:1.

[0186] The amount of acetone in S5 is 10 times the mass of the grafted polylactic acid.

[0187] The mass ratio of tetraethylammonium bromide to grafted polylactic acid in S5 is 0.03:1.

[0188] The concentration of the dilute sulfuric acid solution in S5 is 0.5 mol / L; the amount used is 15 vol% of the volume of acetone.

[0189] The heating and stirring reaction in S5 is carried out at a temperature of 70° C. for 3 hours.

[0190] The auxiliary agents in S7 include 2 wt% of phthalate modified polylactic acid and 0.2 wt% of calcium stearate modified polylactic acid.

[0191] Comparative Example 3: A hot air preparation method for a polylactic acid composite non-woven fabric (polylactic acid is not modified and polycaprolactone is not added):

[0192] S1, taking polylactic acid and an additive and mixing them to obtain a spinning material;

[0193] S2, adding the obtained spinning material into a screw extruder to melt, spinning, winding, drawing, and drying to obtain fibers;

[0194] S3, laying the obtained fibers through a swinging yarn, and subjecting the obtained fiber web to a hot air treatment to shape it into a cloth, thereby obtaining a polylactic acid composite non-woven fabric.

[0195] In S2, the melting temperature is 180°C, the spinning temperature is 190°C, the winding speed is 800 m / min, the drawing temperature is 70°C, and the multiple is 2.2 times.

[0196] The tow spacing of the swing wire in S2 is 5 mm, and the tow tension is 1.5 cN; the laying speed of the web is 20 m / min, the laying angle is 50°, and the number of laying layers is 5.

[0197] In S3, the hot air temperature is 100°C, the hot air speed is 4 m / s, and the hot air combing time is 30 s.

[0198] The auxiliary agents in S1 include phthalate containing 2 wt% of polylactic acid and calcium stearate containing 0.2 wt% of polylactic acid.

[0199] Performance testing:

[0200] Air Permeability Test: Standard: GB / T 5453-1977 "Determination of Air Permeability of Textile Fabrics"; Test Procedure: Randomly cut 10 specimens with a diameter of 50 mm from the nonwoven fabric sample. Clamp one specimen into the air permeability tester, ensuring that the specimen is flat, not deformed, and that both sides of the specimen are properly sealed. Set the pressure differential across the specimen to 100 Pa and adjust the pressure control valve to achieve this pressure difference. When the pressure differential stabilizes at the set value, the instrument automatically displays the gas flow rate permeating the specimen at that time. Calculate the average value for all 10 specimens.

[0201] Strength Test: Standard: Refer to GB / T 24218.3-2010 "Textiles—Nonwovens—Test Methods—Part 3: Determination of Breaking Force and Elongation." Test Procedure: Cut a specimen of specified size from the nonwoven fabric, typically a rectangular shape. Using a tensile testing machine, secure the specimen between the clamps, ensuring it is flat and tension-free. Stretch the specimen at a constant rate until it breaks. Record the maximum force and elongation at break.

[0202] The samples obtained in all the above embodiments and comparative examples were subjected to the above tests, and the results are shown in Table 1.

[0203] Table 1 Product permeability and strength test parameters

[0204] sample <![CDATA[Air permeability m 3 / m 2 ·s]]> Breaking strength N Elongation at break % Example 1 321.5 3818 45.3 Example 2 326.1 3832 48.1 Example 3 324.8 3813 47.6 Example 4 319.6 3857 45.9 Comparative Example 1 322.8 969 19.0 Comparative Example 2 326.3 2781 34.2 Comparative Example 3 317.9 981 19.6

[0205] It can be seen from the experimental data that when the steps of swinging, laying, needling, hot air combing, etc. are the same, the air permeability of the obtained non-woven fabric is almost the same, which meets the use requirements. On this basis, the modified polylactic acid provided by the present invention can greatly improve the breaking strength and elongation of the prepared non-woven fabric. In addition, the polycaprolactone added in step seven is usually used to adjust the elasticity of the fiber in our past research and development. Past data show that the addition of polycaprolactone usually does not have a significant effect on the strength of polylactic acid fiber and the strength of non-woven fabric. When the amount of polycaprolactone added exceeds 25wt% of polylactic acid, the strength of the fiber or non-woven fabric usually decreases significantly. In the present application, it is obvious that there is a certain interaction between the addition of polycaprolactone and the modified polylactic acid provided by the present invention, resulting in a synergistic effect that significantly improves the strength of the final product.

[0206] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0207] The above description of the present invention and its embodiments is non-limiting and only illustrates one embodiment of the present invention. The actual application is not limited thereto. In short, if a person skilled in the art is inspired by the above description and, without departing from the purpose of the present invention, devises methods and embodiments similar to the technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A hot air preparation method for high-permeability and high-strength polylactic acid composite non-woven fabric, characterized by: The following steps are involved: S1. Dissolve polylactic acid in dimethylformamide with stirring, and add potassium persulfate and sodium bisulfite and mix well; S2. Maintaining the reaction temperature and continuing stirring, under nitrogen protection, slowly add ethyl acrylate and butyl acrylate at the same time, gradually add thioglycolic acid, and continue the reaction; S3, after adding trimethylolpropane triacrylate, add triethylamine and continue the reaction; S4, after the reaction is completed, the grafted polylactic acid is separated; S5, dissolving the obtained grafted polylactic acid in acetone with stirring, adding tetraethylammonium bromide to dissolve, slowly adding dilute sulfuric acid solution dropwise, heating and stirring to react; S6. After the reaction is completed, cooling and separation are performed to obtain modified polylactic acid; S7, taking the obtained modified polylactic acid, polycaprolactone, and additives and mixing them to obtain a spinning material; S8, adding the obtained spinning material into a screw extruder to melt, spinning, winding, drawing, and drying to obtain fibers; S9, laying the obtained fibers by swinging the fibers, and subjecting the obtained fiber web to hot air treatment to shape the fiber web into a cloth, thereby obtaining a polylactic acid composite non-woven fabric; The stirring and dissolving in S1 is carried out at 70-75°C; the concentration of polylactic acid in dimethylformamide in S1 is 0.3-0.5g / mL; the mass ratio of polylactic acid, potassium persulfate and sodium bisulfite in S1 is (10-15): (0.04-0.08): (0.03-0.06); the amount ratio of ethyl acrylate to polylactic acid in S2 is 0.15-0.3mL of ethyl acrylate per 1g of polylactic acid; the amount ratio of butyl acrylate to polylactic acid is 0.05-0.1mL of butyl acrylate per 1g of polylactic acid; the amount mass ratio of thioglycolic acid to polylactic acid in S2 is (0.0015-0.0025):1; the amount ratio of trimethylolpropane triacrylate to polylactic acid in S3 is 0.15-0.3mL of trimethylolpropane triacrylate per 1g of polylactic acid. 0.02-0.04mL of alkyl triacrylate; the mass ratio of triethylamine to polylactic acid is (0.0025-0.004):1; the amount of acetone in S5 is 5-10 times the mass of the grafted polylactic acid; the mass ratio of tetraethylammonium bromide to grafted polylactic acid in S5 is (0.01-0.05):1; the concentration of the dilute sulfuric acid solution in S5 is 0.5-1.5mol / L; the amount is 15-25vol% of the volume of acetone; the heating and stirring reaction in S5 is at a temperature of 50-70℃ and a time of 3-7 hours; the amount of polycaprolactone in S7 is 10-12wt% of the modified polylactic acid; the additives in S7 include phthalate in an amount of 2-5wt% of the modified polylactic acid and calcium stearate in an amount of 0.1-0.5wt% of the modified polylactic acid.

2. The hot air preparation method of high-permeability and high-strength polylactic acid composite non-woven fabric according to claim 1, characterized in that: In S8, the melting temperature is 180-200°C, the spinning temperature is 190-230°C, the winding speed is 800-1000m / min; the drawing temperature is 70-90°C, and the multiple is 2.2-3.5 times.

3. The hot air preparation method of high-permeability and high-strength polylactic acid composite non-woven fabric according to claim 1, characterized in that: The tow spacing of the swing wire in S9 is 5-8 mm, and the tow tension is 1.5-2.5 cN; the laying speed of the web is 20-50 m / min, the laying angle is 50-80°, excluding 60°, and the number of laying layers is 5-10 layers.

4. The hot air preparation method of high-permeability and high-strength polylactic acid composite non-woven fabric according to claim 1, characterized in that: In S9, the hot air temperature is 100-130℃ and the hot air speed is 4-8m / s.

5. The hot air preparation method of high-permeability and high-strength polylactic acid composite non-woven fabric according to claim 1, characterized in that: The reaction temperature is maintained at 80-85°C in S2.