Method for preparing degradable polylactic acid nonwoven fabric by hot rolling

Abstract

The application discloses a kind of degradable polylactic acid non-woven fabric hot rolling preparation methods, belong to polylactic acid material preparation technical field, method includes the following steps: preparation required polylactic acid;The obtained polylactic acid is blended with nanocellulose granulation drying to obtain spinning material;The obtained spinning material is added into screw extruder and melts, after drawing, drying, the fiber obtained after spinning winding;The obtained fiber is cut into short fiber, and the short fiber is laid after web and is shaped into cloth by hot rolling, namely the degradable polylactic acid non-woven fabric.The application prepares polylactic acid by specific reagent and method, and adds specific modified reagent in melt spinning, and finally successfully improves the degradable performance of polylactic acid non-woven fabric.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polylactic acid non-woven fabric preparation, and particularly relates to a hot rolling preparation method of degradable polylactic acid non-woven fabric. BACKGROUND

[0002] In today's growing focus on environmental protection and sustainable development, the research and application of degradable materials are particularly important. Among them, polylactic acid (PLA) as a biodegradable polymer material, because it can be made from renewable plant resources and has good biodegradability, has received widespread attention in the field of non-woven fabric preparation. The degradable polylactic acid non-woven fabric hot rolling preparation technology, in short, is a technology that polylactic acid fibers are consolidated into non-woven fabric through hot rolling process. This technology usually includes key steps such as fiber preparation, mixing, melt spinning and hot rolling. In this process, the uniformity of the fibers, the temperature and pressure control of the melt spinning, and the temperature and time of the hot rolling, etc. all have important influence on the performance of the final product. The advantages of this technology are outstanding: first, polylactic acid as a biodegradable material can be completely degraded by microorganisms in nature after use, finally generating carbon dioxide and water, which does not pollute the environment, which is very beneficial to environmental protection; second, polylactic acid non-woven fabric has good physical properties and mechanical strength, which can meet the needs of various application scenarios; finally, with the increasing preference of consumers for environmentally friendly products, polylactic acid non-woven fabric is expected to play an important role in the future market. Looking forward to the prospect of this technology, we can foresee that in the fields of packaging, medical health, agricultural mulch film, etc., degradable polylactic acid non-woven fabric will have a broad application space. Especially in the context of promoting environmental awareness worldwide, the demand for this material will continue to grow.

[0003] However, the existing degradable polylactic acid non-woven fabric preparation technology also has some defects, especially in terms of degradability: degradation rate problem: although polylactic acid has biodegradability, its degradation rate is affected by environmental conditions and material processing methods. In some cases, the degradation rate of polylactic acid may be slow, which may affect its effectiveness in practical applications. Microplastic problem during degradation: during the degradation process, polylactic acid non-woven fabric may produce microplastic particles. These tiny plastic particles may pose a potential threat to the ecological environment, especially they may enter the food chain and have unknown effects on living organisms. Cost problem: although the environmental advantages of polylactic acid are obvious, its production cost is relatively high, which limits the application of polylactic acid non-woven fabric in some fields.

[0004] In order to solve the above problems, researchers are constantly exploring new processes and additives to improve the degradability of polylactic acid non-woven fabric, reduce costs, and promote its application in more fields. In general, although the degradable polylactic acid non-woven fabric hot rolling preparation technology still needs to be improved, its development potential in the field of environmentally friendly materials cannot be underestimated. SUMMARY

[0005] To solve the above problems, the present application mainly optimizes from the aspects of formula and material modification, and provides a hot rolling preparation method of degradable polylactic acid non-woven fabric.

[0006] The hot rolling preparation method of degradable polylactic acid non-woven fabric comprises the following steps:

[0007] S1, preparing polylactic acid required;

[0008] S2, blending and granulating the polylactic acid obtained in step S1 with nanocellulose, and drying to obtain spinning material;

[0009] S3, melting the obtained spinning material in a screw extruder, and after spinning and winding, drawing and drying to obtain fibers;

[0010] S4, cutting the obtained fibers into short fibers, and after webbing, hot rolling and setting to form a fabric, a degradable polylactic acid non-woven fabric is obtained.

[0011] Preferably, the mass ratio of nanocellulose to modified polylactic acid in step S2 is (1-3):100.

[0012] Preferably, the nanocellulose has a fiber diameter of 3-25 nm and a fiber length of 50-500 nm.

[0013] Preferably, the melting in step S3 has a melting temperature of 160-200°C, a spinning temperature of 210-240°C, and a winding speed of 800-1500 m / min; the drawing has a temperature of 50-80°C and a multiple of 3.1-4.5 times.

[0014] Preferably, the short fiber length in step S4 is 1-50 mm; and the hot rolling has a temperature of 100-150°C.

[0015] Preferably, the preparation of polylactic acid required in step S1 can prepare modified polylactic acid: dissolving the modifiers glutamic acid and chitosan in acidic water, adding polylactic acid, adjusting pH, heating and reacting, washing with water after the reaction is completed, and drying to obtain modified polylactic acid.

[0016] Preferably, the mass ratio of glutamic acid to polylactic acid in step S1 is (1-3):100.

[0017] Preferably, the mass ratio of chitosan to polylactic acid in step S1 is (5-9):100.

[0018] Preferably, the acidic water in step S1 has a pH of 5.5-6.0; and the pH is adjusted to 5.5-6.0.

[0019] Preferably, the heating reaction in step S1, stirring the reaction, the reaction temperature is 50-60℃, the reaction time is 4-6h.

[0020] Advantages

[0021] The present application modifies polylactic acid by specific reagents and methods, and adds specific modified reagents in melt spinning, and finally successfully improves the degradable performance of polylactic acid non-woven fabric. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. All other embodiments obtained by those skilled in the art without creative labor on the basis of the embodiments in the present application belong to the protection scope of the present application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to one skilled in the art. In addition, any method and material similar or equivalent to those described can be used in the present application. The preferred implementation methods and materials described herein are only used for demonstration, but cannot limit the content of the present application.

[0024] The experimental methods in the following examples are all conventional methods unless otherwise specified. The experimental materials used in the following examples are all purchased from commercial channels unless otherwise specified. Specifically as follows:

[0025] Polylactic acid particles: NatureWorks 4032D PLA, molecular weight 150,000g / mol;

[0026] Nanocellulose: Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., fiber diameter: 15-25nm (nanoscale), fiber length: 200-300nm;

[0027] Chitosan (CAS 9012-76-4, 99%): Jiangsu Duoyang Biological Engineering Technology Co., Ltd.;

[0028] L-glutamic acid: manufacturer: Xi'an Tianmao Chemical Co., Ltd., high purity GR.

[0029] Example 1: A heat-rolling preparation method of a degradable polylactic acid non-woven fabric:

[0030] S1, the modifier glutamic acid, chitosan is dissolved in acidic water, poly lactic acid is added, the pH is adjusted, and then heated to react, washed with water after the reaction is completed, and dried to obtain modified polylactic acid;

[0031] S2, the modified polylactic acid obtained in step S1 is blended with nanocellulose to obtain a spinning material after granulation and drying;

[0032] S3, the obtained spinning material is added into a screw extruder for melting, and a fiber is obtained after spinning, drawing, and drying;

[0033] S4, the obtained fiber is cut into short fibers, and a degradable polylactic acid non-woven fabric is obtained after webbing and heat setting.

[0034] The mass ratio of glutamic acid to polylactic acid in step S1 is 1:100.

[0035] The mass ratio of chitosan to polylactic acid in step S1 is 5:100.

[0036] The pH of the acidic water in step S1 is 5.5; and the pH is adjusted to 5.5.

[0037] The reaction temperature of the heating reaction in step S1 is 50°C, and the reaction time is 4h.

[0038] The mass ratio of nanocellulose to modified polylactic acid in step S2 is 1:100.

[0039] The melting temperature in step S3 is 160°C; the spinning temperature is 210°C; the drawing temperature is 50°C, and the multiple is 3.1 times; and the winding speed is 800m / min.

[0040] The length of the short fiber in step S4 is 20mm; and the heat setting temperature in step S4 is 100°C.

[0041] Example 2: a heat setting preparation method of a degradable polylactic acid non-woven fabric:

[0042] S1, a modifier glutamic acid and chitosan are dissolved in acidic water, polylactic acid is added, the pH is adjusted, and a heating reaction is performed, and then water washing and drying are performed to obtain modified polylactic acid;

[0043] S2, the modified polylactic acid obtained in step S1 is blended with nanocellulose to obtain a spinning material after granulation and drying;

[0044] S3, the obtained spinning material is added into a screw extruder for melting, and a fiber is obtained after spinning, drawing, and drying;

[0045] S4, the obtained fiber is cut into short fibers, and a degradable polylactic acid non-woven fabric is obtained after webbing and heat setting.

[0046] The mass ratio of glutamic acid to polylactic acid in step S1 is 3:100.

[0047] The mass ratio of the chitosan to the polylactic acid in step S1 is 9:100.

[0048] The acidic water in step S1 has a pH of 5.5; and the pH is adjusted to 5.5.

[0049] The heating reaction in step S1 is a stirring reaction, the reaction temperature is 50℃, and the reaction time is 4h.

[0050] The mass ratio of the nanocellulose to the modified polylactic acid in step S2 is 1:100.

[0051] The melting in step S3 is at a temperature of 160℃; the spinning temperature is 210℃; the drawing temperature is 50℃, the multiple is 3.1 times; and the winding speed is 800m / min.

[0052] The short fiber length in step S4 is 20mm; and the hot rolling in step S4 is at a temperature of 100℃.

[0053] Example 3: A hot rolling preparation method of a degradable polylactic acid non-woven fabric:

[0054] S1, dissolving a modifier glutamic acid and chitosan in acidic water, adding polylactic acid, adjusting pH, heating reaction, washing with water after the reaction is completed, and drying to obtain modified polylactic acid;

[0055] S2, blending, granulating, and drying the modified polylactic acid obtained in step S1 with nanocellulose to obtain a spinning material;

[0056] S3, melting the obtained spinning material in a screw extruder, drawing and drying after spinning and winding to obtain a fiber;

[0057] S4, cutting the obtained fiber into short fibers, laying the short fibers, and hot rolling and setting the short fibers to form a fabric, thereby obtaining a degradable polylactic acid non-woven fabric.

[0058] The mass ratio of the glutamic acid to the polylactic acid in step S1 is 2:100.

[0059] The mass ratio of the chitosan to the polylactic acid in step S1 is 7:100.

[0060] The acidic water in step S1 has a pH of 5.5; and the pH is adjusted to 5.5.

[0061] The heating reaction in step S1 is a stirring reaction, the reaction temperature is 50℃, and the reaction time is 4h.

[0062] The mass ratio of the nanocellulose to the modified polylactic acid in step S2 is 1:100.

[0063] The melting temperature is 160 DEG C; the spinning temperature is 210 DEG C; the drawing temperature is 50 DEG C, the multiple is 3.1 times; and the winding speed is 800 m / min.

[0064] The length of the short fiber is 20 mm; and the hot rolling temperature is 100 DEG C.

[0065] Embodiment 4: A hot rolling preparation method of a degradable polylactic acid non-woven fabric:

[0066] S1, dissolving the modifiers glutamic acid and chitosan in acidic water, adding polylactic acid, adjusting pH, heating and reacting, washing with water after the reaction is completed, and drying to obtain modified polylactic acid;

[0067] S2, blending, granulating and drying the modified polylactic acid obtained in step S1 with nanocellulose to obtain a spinning material;

[0068] S3, melting the obtained spinning material in a screw extruder, drawing and drying after spinning and winding to obtain a fiber;

[0069] S4, cutting the obtained fiber into short fibers, laying the short fibers, and hot rolling and setting the short fibers to form a fabric, thereby obtaining a degradable polylactic acid non-woven fabric.

[0070] The mass ratio of glutamic acid to polylactic acid in step S1 is 2:100.

[0071] The mass ratio of chitosan to polylactic acid in step S1 is 7:100.

[0072] The acidic water in step S1 has a pH of 5.5; and the pH is adjusted to 5.5.

[0073] The heating and reaction in step S1 is stirring and reaction, the reaction temperature is 50 DEG C, and the reaction time is 4 h.

[0074] The mass ratio of nanocellulose to modified polylactic acid in step S2 is 3:100.

[0075] The melting temperature is 160 DEG C; the spinning temperature is 210 DEG C; the drawing temperature is 50 DEG C, the multiple is 3.1 times; and the winding speed is 800 m / min.

[0076] The length of the short fiber is 20 mm; and the hot rolling temperature is 100 DEG C.

[0077] Embodiment 5: A hot rolling preparation method of a degradable polylactic acid non-woven fabric:

[0078] S1, dissolving the modifiers glutamic acid and chitosan in acidic water, adding polylactic acid, adjusting pH, heating and reacting, washing with water after the reaction is completed, and drying to obtain modified polylactic acid;

[0079] S2, the modified polylactic acid obtained in step S1 is blended with nanocellulose to obtain a spinning material after granulation and drying;

[0080] S3, the obtained spinning material is added to a screw extruder for melting, and a fiber is obtained after spinning, drawing, and drying;

[0081] S4, the obtained fiber is cut into short fibers, and a degradable polylactic acid non-woven fabric is obtained by webbing and heat setting the short fibers.

[0082] The mass ratio of glutamic acid to polylactic acid in step S1 is 2:100.

[0083] The mass ratio of chitosan to polylactic acid in step S1 is 7:100.

[0084] The acid water in step S1 has a pH of 5.5; the pH is adjusted to 5.5.

[0085] The heating reaction in step S1 is stirred at a reaction temperature of 50°C for 4h.

[0086] The mass ratio of nanocellulose to modified polylactic acid in step S2 is 2:100.

[0087] The melting temperature in step S3 is 160°C; the spinning temperature is 210°C; the drawing temperature is 50°C, and the multiple is 3.1 times; the winding speed is 800m / min.

[0088] The length of the short fibers in step S4 is 20mm; the heat setting temperature in step S4 is 100°C.

[0089] Example 6: A heat setting method for preparing a degradable polylactic acid non-woven fabric:

[0090] S1, the modifier glutamic acid and chitosan are dissolved in acid water, polylactic acid is added, the pH is adjusted, and the reaction is heated, then washed with water and dried to obtain modified polylactic acid;

[0091] S2, the modified polylactic acid obtained in step S1 is blended with nanocellulose to obtain a spinning material after granulation and drying;

[0092] S3, the obtained spinning material is added to a screw extruder for melting, and a fiber is obtained after spinning, drawing, and drying;

[0093] S4, the obtained fiber is cut into short fibers, and a degradable polylactic acid non-woven fabric is obtained by webbing and heat setting the short fibers.

[0094] The mass ratio of glutamic acid to polylactic acid in step S1 is 2:100.

[0095] The mass ratio of the chitosan to the polylactic acid in step S1 is 7:100.

[0096] The acidic water in step S1 has a pH of 6.0; and the pH is adjusted to 6.0.

[0097] The heating reaction in step S1 is a stirring reaction, the reaction temperature is 60℃, and the reaction time is 6h.

[0098] The mass ratio of the nanocellulose to the modified polylactic acid in step S2 is 2:100.

[0099] The melting in step S3 is at a temperature of 200℃; the spinning temperature is 240℃; the drawing temperature is 50℃, the multiple is 3.1 times; and the winding speed is 1000m / min.

[0100] The short fiber length in step S4 is 20mm; and the hot rolling in step S4 is at a temperature of 150℃.

[0101] Example 7: A hot rolling preparation method of a degradable polylactic acid non-woven fabric:

[0102] S1, dissolving a modifier glutamic acid and chitosan in acidic water, adding polylactic acid, adjusting pH, heating reaction, washing with water after the reaction is completed, and drying to obtain modified polylactic acid;

[0103] S2, blending, granulating, and drying the modified polylactic acid obtained in step S1 with nanocellulose to obtain a spinning material;

[0104] S3, melting the obtained spinning material in a screw extruder, drawing and drying after spinning and winding to obtain a fiber;

[0105] S4, cutting the obtained fiber into short fibers, laying the short fibers, and hot rolling to form a fabric, thereby obtaining a degradable polylactic acid non-woven fabric.

[0106] The mass ratio of the glutamic acid to the polylactic acid in step S1 is 2:100.

[0107] The mass ratio of the chitosan to the polylactic acid in step S1 is 7:100.

[0108] The acidic water in step S1 has a pH of 6.0; and the pH is adjusted to 5.5.

[0109] The heating reaction in step S1 is a stirring reaction, the reaction temperature is 55℃, and the reaction time is 5h.

[0110] The mass ratio of the nanocellulose to the modified polylactic acid in step S2 is 2:100.

[0111] The melting temperature is 180 DEG C; the spinning temperature is 220 DEG C; the drawing temperature is 50 DEG C, the multiple is 3.1 times; and the winding speed is 900 m / min.

[0112] The short fiber length in step S4 is 20 mm; and the hot rolling temperature in step S4 is 130 DEG C.

[0113] Comparative Example 1: A hot rolling preparation method of a degradable polylactic acid non-woven fabric (without adding glutamic acid modification):

[0114] S1, dissolving a modifier chitosan in acidic water, adding polylactic acid, adjusting pH, heating and reacting, washing with water after the reaction is completed, and drying to obtain modified polylactic acid;

[0115] S2, taking the modified polylactic acid obtained in step S1 and blending, granulating, and drying nano-cellulose to obtain a spinning material;

[0116] S3, melting the obtained spinning material in a screw extruder, drawing, drying after spinning and winding to obtain a fiber;

[0117] S4, cutting the obtained fiber into short fibers, laying the short fibers into a web, and hot rolling and setting to form a fabric, thereby obtaining a degradable polylactic acid non-woven fabric.

[0118] The mass ratio of chitosan to polylactic acid in step S1 is 7:100.

[0119] The acidic water in step S1 has a pH of 6.0; and the pH is adjusted to 5.5.

[0120] The heating reaction in step S1 is stirring reaction, the reaction temperature is 55 DEG C, and the reaction time is 5 h.

[0121] The mass ratio of nano-cellulose to modified polylactic acid in step S2 is 2:100.

[0122] The melting temperature is 180 DEG C; the spinning temperature is 220 DEG C; the drawing temperature is 50 DEG C, the multiple is 3.1 times; and the winding speed is 900 m / min.

[0123] The short fiber length in step S4 is 20 mm; and the hot rolling temperature in step S4 is 130 DEG C.

[0124] Comparative Example 2: A hot rolling preparation method of a degradable polylactic acid non-woven fabric (without adding chitosan modification):

[0125] S1, dissolving a modifier glutamic acid in acidic water, adding polylactic acid, adjusting pH, heating and reacting, washing with water after the reaction is completed, and drying to obtain modified polylactic acid;

[0126] S2, the modified polylactic acid obtained in step S1 is blended with nanocellulose to obtain a spinning material after granulation and drying;

[0127] S3, the obtained spinning material is added into a screw extruder for melting, and a fiber is obtained after spinning, drawing, drying, and winding;

[0128] S4, the obtained fiber is cut into short fibers, and a degradable polylactic acid non-woven fabric is obtained after webbing and hot rolling.

[0129] The mass ratio of glutamic acid to polylactic acid in step S1 is 2:100.

[0130] The pH of the acidic water in step S1 is 6.0; and the pH is adjusted to 5.5.

[0131] The reaction temperature of the heating reaction in step S1 is 55°C, and the reaction time is 5h.

[0132] The mass ratio of nanocellulose to modified polylactic acid in step S2 is 2:100.

[0133] The melting temperature in step S3 is 180°C; the spinning temperature is 220°C; the drawing temperature is 50°C, and the multiple is 3.1 times; and the winding speed is 900m / min.

[0134] The length of the short fibers in step S4 is 20mm; and the hot rolling temperature in step S4 is 130°C.

[0135] Comparative Example 3: A hot rolling preparation method of a degradable polylactic acid non-woven fabric (without adding nanocellulose modification):

[0136] S1, the modifier glutamic acid and chitosan are dissolved in acidic water, polylactic acid is added, the pH is adjusted, and then heated to react, washed with water after the reaction is completed, and dried to obtain modified polylactic acid;

[0137] S2, the obtained polylactic acid is added into a screw extruder for melting, and a fiber is obtained after spinning, drawing, drying, and winding;

[0138] S3, the obtained fiber is cut into short fibers, and a degradable polylactic acid non-woven fabric is obtained after webbing and hot rolling.

[0139] The mass ratio of glutamic acid to polylactic acid in step S1 is 2:100.

[0140] The mass ratio of chitosan to polylactic acid in step S1 is 7:100.

[0141] The pH of the acidic water in step S1 is 6.0; and the pH is adjusted to 5.5.

[0142] The heating reaction in step S1 is stirred, the reaction temperature is 55°C, and the reaction time is 5h.

[0143] The melting in step S2 is at a temperature of 180°C; the spinning temperature is 220°C; the drawing temperature is 50°C, the multiple is 3.1 times; and the winding speed is 900m / min.

[0144] The short fiber length in step S3 is 20mm; and the hot rolling in step S4 is at a temperature of 130°C.

[0145] Comparative Example 4: A hot rolling preparation method of a degradable polylactic acid non-woven fabric (only adding glutamic acid modification):

[0146] S1, dissolving the modifier glutamic acid in acidic water, adding polylactic acid, adjusting pH, and then heating reaction, washing with water after the reaction is completed, and drying to obtain modified polylactic acid;

[0147] S2, melting the obtained polylactic acid in a screw extruder, drawing and drying after spinning and winding to obtain fibers;

[0148] S3, cutting the obtained fibers into short fibers, laying the short fibers into a web, and then hot rolling to form a fabric, thereby obtaining a degradable polylactic acid non-woven fabric.

[0149] The mass ratio of glutamic acid to polylactic acid in step S1 is 2:100.

[0150] The acidic water in step S1 has a pH of 6.0; and the pH is adjusted to 5.5.

[0151] The heating reaction in step S1 is stirred, the reaction temperature is 55°C, and the reaction time is 5h.

[0152] The melting in step S2 is at a temperature of 180°C; the spinning temperature is 220°C; the drawing temperature is 50°C, the multiple is 3.1 times; and the winding speed is 900m / min.

[0153] The short fiber length in step S3 is 20mm; and the hot rolling in step S4 is at a temperature of 130°C.

[0154] Comparative Example 5: A hot rolling preparation method of a degradable polylactic acid non-woven fabric (only adding chitosan modification):

[0155] S1, dissolving the modifier chitosan in acidic water, adding polylactic acid, adjusting pH, and then heating reaction, washing with water after the reaction is completed, and drying to obtain modified polylactic acid;

[0156] S2, melting the obtained polylactic acid in a screw extruder, drawing and drying after spinning and winding to obtain fibers;

[0157] S3, cut the obtained fiber into short fibers, lay the short fibers after webbing, and heat roll to form a cloth, to obtain a degradable polylactic acid non-woven fabric.

[0158] The mass ratio of chitosan to polylactic acid in step S1 is 7:100.

[0159] The acidic water in step S1 has a pH of 6.0; and the pH is adjusted to 5.5.

[0160] The heating reaction in step S1 is a stirring reaction, the reaction temperature is 55°C, and the reaction time is 5h.

[0161] The melting in step S2 has a melting temperature of 180°C; the spinning temperature is 220°C; the drawing temperature is 50°C, the multiple is 3.1 times; and the winding speed is 900m / min.

[0162] The short fiber length in step S3 is 20mm; and the heat rolling in step S4 has a temperature of 130°C.

[0163] Comparative Example 6: A heat rolling preparation method of a degradable polylactic acid non-woven fabric (only adding nano-cellulose modification, step S1 is a parallel control):

[0164] S1, adding polylactic acid in acidic water, adjusting the pH, heating reaction, washing with water after the reaction is completed, and drying to obtain polylactic acid;

[0165] S2, taking the polylactic acid obtained in step S1 and blending with nano-cellulose to granulate and dry to obtain a spinning material;

[0166] S3, melting the obtained spinning material in a screw extruder, spinning and winding, drawing, and drying to obtain a fiber;

[0167] S4, cutting the obtained fiber into short fibers, laying the short fibers after webbing, and heat rolling to form a cloth, to obtain a degradable polylactic acid non-woven fabric.

[0168] The acidic water in step S1 has a pH of 6.0; and the pH is adjusted to 5.5.

[0169] The heating reaction in step S1 is a stirring reaction, the reaction temperature is 55°C, and the reaction time is 5h.

[0170] The mass ratio of nano-cellulose to polylactic acid in step S2 is 2:100.

[0171] The melting in step S3 has a melting temperature of 180°C; the spinning temperature is 220°C; the drawing temperature is 50°C, the multiple is 3.1 times; and the winding speed is 900m / min.

[0172] The length of the short fiber in step S4 is 20 mm; the temperature of the hot rolling in step S4 is 130 °C.

[0173] Comparative Example 7: A hot rolling method for preparing a degradable polylactic acid non-woven fabric (only adding nano-cellulose modification, step S1 is not performed):

[0174] S1, blending and granulating polylactic acid and nano-cellulose to obtain a spinning material after drying;

[0175] S2, melting the obtained spinning material in a screw extruder, and after spinning, winding, drawing, and drying, a fiber is obtained;

[0176] S3, cutting the obtained fiber into short fibers, and after webbing the short fibers, hot rolling is performed to form a fabric, thereby obtaining a degradable polylactic acid non-woven fabric.

[0177] The mass ratio of nano-cellulose to polylactic acid in step S1 is 2:100.

[0178] The melting temperature in step S2 is 180 °C; the spinning temperature is 220 °C; the drawing temperature is 50 °C, and the multiple is 3.1 times; the winding speed is 900 m / min.

[0179] The length of the short fiber in step S3 is 20 mm; the temperature of the hot rolling in step S4 is 130 °C.

[0180] Comparative Example 8: A hot rolling method for preparing a degradable polylactic acid non-woven fabric (without modifying the raw materials, and optimizing the material mixing):

[0181] S1, blending and granulating polylactic acid, glutamic acid, chitosan, and nano-cellulose to obtain a spinning material after drying;

[0182] S2, melting the obtained spinning material in a screw extruder, and after spinning, winding, drawing, and drying, a fiber is obtained;

[0183] S3, cutting the obtained fiber into short fibers, and after webbing the short fibers, hot rolling is performed to form a fabric, thereby obtaining a degradable polylactic acid non-woven fabric.

[0184] The mass ratio of glutamic acid to polylactic acid in step S1 is 2:100.

[0185] The mass ratio of chitosan to polylactic acid in step S1 is 7:100.

[0186] The mass ratio of nano-cellulose to polylactic acid in step S1 is 2:100.

[0187] The melting temperature in step S2 is 180 °C; the spinning temperature is 220 °C; the drawing temperature is 50 °C, and the multiple is 3.1 times; the winding speed is 900 m / min.

[0188] The length of the short fiber in step S3 is 20 mm; and the temperature of the hot rolling in step S4 is 130°C.

[0189] Blank control 1: a hot rolling preparation method of a degradable polylactic acid non-woven fabric (without any modification, step S1 is used as a control):

[0190] S1, adding polylactic acid into acidic water, adjusting pH, heating reaction, washing with water after the reaction is completed, and drying to obtain polylactic acid;

[0191] S2, melting the obtained polylactic acid in a screw extruder, drawing, drying after spinning and winding to obtain a fiber;

[0192] S3, cutting the obtained fiber into short fibers, laying the short fibers, and hot rolling to shape the fabric, thereby obtaining a degradable polylactic acid non-woven fabric.

[0193] The pH of the acidic water in step S1 is 6.0; and the pH is adjusted to 5.5.

[0194] The heating reaction in step S1 is stirring reaction, the reaction temperature is 55°C, and the reaction time is 5 h.

[0195] The melting temperature in step S2 is 180°C; the spinning temperature is 220°C; the drawing temperature is 50°C, the multiple is 3.1 times; and the winding speed is 900 m / min.

[0196] The length of the short fiber in step S3 is 20 mm; and the temperature of the hot rolling in step S4 is 130°C.

[0197] Blank control 2: a hot rolling preparation method of a degradable polylactic acid non-woven fabric (without any modification, step S1 is not operated):

[0198] S1, melting polylactic acid in a screw extruder, drawing, drying after spinning and winding to obtain a fiber;

[0199] S2, cutting the obtained fiber into short fibers, laying the short fibers, and hot rolling to shape the fabric, thereby obtaining a degradable polylactic acid non-woven fabric.

[0200] The melting temperature in step S1 is 180°C; the spinning temperature is 220°C; the drawing temperature is 50°C, the multiple is 3.1 times; and the winding speed is 900 m / min.

[0201] The length of the short fiber in step S3 is 20 mm; and the temperature of the hot rolling in step S4 is 130°C.

[0202] Performance test: compost degradation rate: the degradation rate of the sample was evaluated according to the method for determining the released carbon dioxide in the method for determining the released carbon dioxide in GB / T 19277.1-2011 "Determination of ultimate aerobic biodegradation of materials under controlled composting conditions using the method for determining released carbon dioxide". Breaking strength: according to GB / T 3923.1-1997 standard.

[0203] The compost used in the experimental evaluation was prepared according to the above standard GB / T 19277.1-2011, and the same mass of the sample of the examples and the comparative examples was accurately weighed and mixed with the same fixed mass of the compost as the sample group; the sample containing only the compost was blank control group 3. The carbon dioxide absorption bottle was titrated at intervals, and the carbon dioxide release amount was calculated to calculate the biodegradation rate. The specific calculation method is: the amount of carbon dioxide collected in the sample group absorption bottle is titrated, converted into the corresponding carbon content W1, subtracted from the carbon content W2 calculated by the carbon dioxide released by the blank group, and divided by the total carbon content W0 in the sample to obtain the biodegradation rate. The calculation formula is as follows:

[0204]

[0205] After detection, the non-woven fabrics obtained in all the examples and the comparative examples had a longitudinal breaking strength greater than 96.7-159.2 N / 5 cm, and a transverse breaking strength greater than 99.1-172.6 N / 5 cm, and the mechanical parameters met the application requirements. The compost degradation rate data is shown in Table 1.

[0206] Table 1: Compost degradation rate test results of samples

[0207]

[0208] From the experimental data, it can be seen that the addition of nanocellulose in the mixing and melting step slightly improves the degradability of the non-woven fabric, and if the modifier chitosan and glutamic acid are added in the mixing and melting step, there is almost no contribution to the degradability. From the data, it can be seen that the two modifiers used to modify polylactic acid and the nanocellulose added in the mixing and melting step have a synergistic effect on the degradation performance of the polylactic acid non-woven fabric, and are indispensable and have a relatively fixed role, which shows that the intermolecular combination between polylactic acid and chitosan and glutamic acid in the modification step cannot be achieved by simple mixing or temperature, although the specific mechanism still needs further research, but the biodegradability of the polylactic acid non-woven fabric product provided by the present application has made it widely used in many aspects.

[0209] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary and that changes can be made in the embodiments without departing from the spirit and scope of the application, which is defined by the appended claims and their equivalents.

[0210] The above description of the application and its embodiments is not restrictive, and the shown is only one of the embodiments of the application, and the actual application is not limited thereto. In general, if a person skilled in the art is inspired by it, without departing from the purpose of the invention, without creative design, similar ways and embodiments of the technical solution should belong to the protection scope of the application.

Claims

1. A method for preparing biodegradable polylactic acid nonwoven fabric by hot rolling, characterized in that: Includes the following steps: S1. Preparation of the required polylactic acid: Dissolve the modifiers glutamic acid and chitosan in acidic water, add polylactic acid, adjust the pH, heat the reaction, wash with water and dry after the reaction is completed to obtain modified polylactic acid; the mass ratio of glutamic acid to polylactic acid is (1-3):100; the mass ratio of chitosan to polylactic acid is (5-9):100; the acidic water has a pH of 5.5-6.0; the pH is adjusted to 5.5-6.0; the reaction temperature is 50-60℃ and the reaction time is 4-6h. S2. Take the polylactic acid obtained in step S1, granulate it with nanocellulose, and dry it to obtain a spinning material. S3. The obtained spinning material is added to a screw extruder for melting, and after spinning, winding, stretching, and drying, fibers are obtained. S4. Cut the obtained fibers into short fibers, lay the short fibers into a web, and then heat-roll and shape them into fabric to obtain biodegradable polylactic acid nonwoven fabric. The mass ratio of nanocellulose to modified polylactic acid in step S2 is (1-3):100; the nanocellulose in step S2 is fibrous with a diameter of 3-25 nm and a length of 50-500 nm; the spinning temperature in step S3 is 210-240℃ and the winding speed is 800-1500 m / min; the drawing temperature in step S3 is 50-80℃ and the multiple is 3.1-4.5 times; the short fiber length in step S4 is 1-50 mm; the hot rolling temperature is 100-150℃.

2. The method for preparing biodegradable polylactic acid nonwoven fabric by hot rolling according to claim 1, characterized in that: The melting process described in step S3 is carried out at a temperature of 160-200℃.

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