A degradable polylactic acid two-component spunbond nonwoven material and its preparation method and application

Abstract

The present invention discloses a degradable polylactic acid bicomponent spunbond nonwoven material and its preparation method, relating to the technical field of nonwoven materials. The present invention uses spinning-grade polylactic acid chips as the core layer raw material, and a low-melting-point blended pellet obtained by mixing low-melting-point PLA chips, modified polyethylene, polylactic acid-ethylene copolymer, and a compatibilizer as the skin layer raw material to produce a nonwoven fabric with a skin-core structure. The polyethylene is modified using carboxymethyl starch and dopamine. The polylactic acid bicomponent spunbond nonwoven material produced by the present invention has good tensile properties, air permeability, and heat sealing strength.

Description

Technical Field

[0001] The present invention relates to the technical field of non-woven fabric materials, and in particular to a degradable polylactic acid two-component spunbonded non-woven material and a preparation method and application thereof. Background Art

[0002] Polylactic acid (PLA) is a biodegradable, environmentally friendly aliphatic polyester polymer material. It is polymerized from lactic acid produced by the fermentation of crops. After being discarded, it can be degraded into carbon dioxide and water by the actions of microorganisms, acids, alkalis, etc. It has good mechanical and physical properties and is suitable for injection molding, spinning, film drawing, etc. It is widely used in medical care, health, agriculture, textile and clothing industry, automotive decoration and other fields.

[0003] Currently, PLA spunbond nonwovens mostly use single-component PLA as raw material, which has low requirements for the control of production equipment and process parameters, and the product's thermal bonding performance is poor. In addition, due to the brittle performance and low heat resistance of polylactic acid materials, the mechanical properties of polylactic acid nonwovens prepared by the spunbond method are difficult to meet the requirements of some application fields. Many inventions have solved this problem by modifying the polylactic acid molecules or spinning them together with other polymer materials.

[0004] In the prior art, CN105133082A discloses a low-melting-point sheath-core polylactic acid composite fiber and a preparation method thereof. The sheath of the composite fiber is low-melting-point polylactic acid, and the core is spinning-grade polylactic acid. The polylactic acid composite fiber obtained using the sheath-core structure has good bulkiness and high elastic recovery rate, and can be used for thermal bonding to form non-woven fabrics. However, the low-melting-point polylactic acid used therein has a high relative viscosity and poor spinnability, and the tensile strength of the non-woven fabric obtained using the composite fiber is not high. CN101362853B discloses a low-cost fully biodegradable polylactic acid sheet and a preparation method thereof. The polylactic acid sheet is prepared from a high molecular weight polylactic acid resin, a low molecular weight polylactic acid resin, and processing aids (thermal stability, lubricant, plasticizer, and hydrolysis resistance agent). The obtained polylactic acid sheet has good durability and good secondary moldability. While the addition of these additives can improve the formability of polylactic acid materials, the resulting polylactic acid is only suitable for sheet processing and cannot be processed at the spinning level. CN113308803B discloses a method for preparing a fully biodegradable nonwoven fabric using a spunbond process. The method comprises the following steps: mixing a caprolactone-lactic acid random copolymer with polylactic acid to obtain a copolymer-modified PLA; then blending the copolymer-modified PLA, PHBV, silica, a compatibilizer, and a chain extender to obtain a blend, and then spunbonding the resulting nonwoven fabric. The process is complex and difficult to mass-produce.

[0005] Therefore, by modifying polylactic acid to prepare a spunbond nonwoven material, the spunbond nonwoven material can be made degradable and have good tensile properties, air permeability and heat sealing strength. Summary of the Invention

[0006] In response to the shortcomings of the prior art, the present invention provides a degradable polylactic acid bicomponent spunbond nonwoven material and a method for preparing the same. The present invention modifies polyethylene using dopamine and carboxymethyl cellulose to produce a modified polyethylene. The modified polyethylene is then mixed with low-melting-point PLA chips and a polylactic acid-ethylene copolymer to produce a low-melting-point blended pellet. The low-melting-point blended pellet is then spunbonded using the low-melting-point blended pellet as the sheath material and spinning-grade polylactic acid chips as the core material to produce a polylactic acid bicomponent spunbond nonwoven material. The resulting polylactic acid bicomponent spunbond nonwoven material is degradable and exhibits excellent tensile properties, air permeability, and heat-seal strength.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The first aspect of the present invention provides a method for preparing a degradable polylactic acid two-component spunbond nonwoven material:

[0009] (1) polyethylene, carboxymethyl starch, sodium trimetaphosphate and water are mixed, reacted once and dried to obtain a reaction product; the reaction product, dopamine and potassium dihydrogen phosphate-disodium hydrogen phosphate solution are then mixed, and reacted twice to obtain modified polyethylene;

[0010] (2) mixing low-melting-point PLA chips, modified polyethylene, polylactic acid-ethylene copolymer, and a compatibilizer, and heating and melting the mixture to obtain low-melting-point blended pellets;

[0011] (3) Low melting point blended pellets are used as the raw material for the skin layer and spinning-grade polylactic acid chips are used as the raw material for the core layer. The polylactic acid two-component spunbond nonwoven material is prepared by the spunbond method.

[0012] Preferably, in step (1), the mass ratio of the carboxymethyl starch, polyethylene, sodium trimetaphosphate and water is (3-5): (15-20): (0.05-0.25): 300; the addition amount ratio of dopamine, potassium dihydrogen phosphate-disodium hydrogen phosphate solution and the reaction product is (0.2-0.8) g: 1 L: (0.2-0.8) g.

[0013] Preferably, in step (1), the primary reaction temperature is 80-90° C., the reaction time is 15-25 min, and the secondary reaction time is 20-25 h.

[0014] Preferably, in step (1), the drying temperature is 90-100° C. and the drying time is 30 min.

[0015] Preferably, in step (2), the mass ratio of low-melting-point PLA chips, modified polyethylene, polylactic acid-ethylene copolymer, and compatibilizer is (70-85): (5-10): (2-5): (0.005-0.1).

[0016] Preferably, in step (2), the compatibilizer is one or more of polyolefin grafted maleic anhydride, glycidyl methacrylate, 4,4'-methylenebis(phenyl isocyanate), and PLA-based compatibilizer masterbatch.

[0017] Preferably, in step (2), the heating and melting temperature is 170-230°C.

[0018] Preferably, in step (2), the density of the low melting point PLA slice is 1.2-1.3 g / cm 3 , melting point is 145-155℃, melt index at 190℃ is 3-12g / 10min, and glass transition temperature is 56-60℃.

[0019] Preferably, in step (3), the density of the spinning-grade polylactic acid chips is 1.2-1.3 g / cm 3 , melting point is 170-180℃, melt index at 190℃ is 9-15g / 10min, and glass transition temperature is 56-60℃.

[0020] Preferably, in step (3), the specific operation of preparing the polylactic acid two-component spunbond nonwoven material by the spunbond method is as follows: low-melting-point blended pellets are used as the skin layer raw material, and spinning-grade polylactic acid chips are used as the core layer raw material. After drying, they are melt-extruded, metered, cooled, and stretched to obtain filaments. The filaments are thermally bonded, pre-shaped, and thermally reinforced to obtain the polylactic acid two-component spunbond nonwoven material.

[0021] More preferably, the drying temperature is 65-75° C. and the drying time is 10-15 h, so as to control the moisture content of the skin layer raw material and the core layer raw material to be ≤30 ppm.

[0022] More preferably, the melt extrusion temperature of the dried low-melting-point blended pellets is 170-230°C, and the melt extrusion temperature of the dried spinning-grade polylactic acid chips is 190-250°C.

[0023] More preferably, the mass ratio of the skin layer raw material to the core layer raw material is (2-8): (2-8).

[0024] More preferably, side blowing is used for cooling, and the temperature of the side blowing air flow is 15-35° C. and the wind pressure is 220-280 Pa.

[0025] More preferably, the stretching air pressure is 0.15-0.30 MPa.

[0026] More preferably, the specific operation of thermal bonding is: the filaments obtained by drawing are passed through a pre-roller, a roller and heat-set to obtain the polylactic acid two-component spunbond nonwoven material.

[0027] Further preferably, during the pre-setting process, the temperature is 35-90°C; during the heat consolidation process, the temperature is 95-155°C, and the line pressure is 40-95N / mm; during the heat setting process, the temperature is 120-145°C, and the opening of the circulating air is 30% to 60%.

[0028] More preferably, the filaments obtained by drawing are sheath-core bicomponent fibers, and the shapes of the fibers are circular, trilobal, triangular, quadrilateral or other polygonal shapes.

[0029] More preferably, the diameter of the filament is 8-30 μm.

[0030] Preferably, the surface density of the polylactic acid bicomponent spunbonded nonwoven material is 15-150 g / m 2 .

[0031] The second aspect of the present invention provides a degradable polylactic acid bicomponent spunbond nonwoven material.

[0032] The third aspect of the present invention provides the use of a degradable polylactic acid two-component spunbond nonwoven material in the preparation of filtration products and food packaging products.

[0033] Beneficial effects of the present invention:

[0034] The present invention uses spinning-grade polylactic acid chips as core layer raw materials, and uses low-melting-point PLA chips, modified polyethylene chips, and polylactic acid-ethylene copolymer as skin layer raw materials. The polyethylene chips modified with dopamine and carboxymethyl starch play a better softening and bonding role, thereby increasing the strength and heat sealing strength of the non-woven material, while the polylactic acid-ethylene copolymer improves the compatibility between the modified polyethylene and polylactic acid in the skin layer components. At the same time, when the two-component fibers are consolidated into a web by hot air, the skin layer melts while the core layer does not melt, thereby maintaining the fluffiness of the fiber web, thereby increasing the air permeability of the non-woven fabric, so that the final non-woven fabric with a skin-core structure has good tensile properties, air permeability and heat sealing strength.

[0035] The low-melting-point blended pellets produced by the present invention have a lower melting point than spinning-grade polylactic acid. When used as the low-melting-point component of the cortex, they can better soften and bond, thereby enhancing the tensile and heat-sealing properties of the polylactic acid nonwoven material. The polylactic acid-ethylene copolymer used as a fluxing agent can be localized in the cross-section between the components, thereby reducing the repulsive forces between the components in the low-melting-point blended pellets and improving the compatibility between the modified polyethylene and the low-melting-point PLA slices, thereby enhancing the stability of the low-melting-point blended pellets during the spinning process.

[0036] Specific embodiment

[0037] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0038] PLA nonwovens are mostly made from single-component PLA, but the mechanical properties of nonwovens made from single-component PLA are poor. Therefore, existing technologies often use two-component PLA to produce nonwoven materials. PLA nonwovens made from spinning-grade PLA and low-melting-point PLA, using a sheath-core structure, are also often made. However, due to the high viscosity and poor spinnability of low-melting-point nonwovens, the resulting PLA nonwovens have low tensile properties.

[0039] Based on this, the present invention provides a two-component polylactic acid non-woven fabric, which has a skin-core structure. The skin layer is made of a mixture of low-melting-point PLA chips, modified polyethylene, polylactic acid-ethylene copolymer, and a compatibilizer, while the core layer is made of spinning-grade polylactic acid chips. Adding modified polyethylene to the low-melting-point PLA chips can enhance the strength and heat-sealing properties of the resulting non-woven fabric, while the polylactic acid-ethylene copolymer provides compatibility between the low-melting-point polylactic acid and the modified polyethylene, thereby enhancing the tensile strength and heat-sealing properties of the resulting non-woven fabric. At the same time, when the two-component polylactic acid fibers are consolidated into a web by hot air, the skin layer melts while the core layer does not, maintaining the fluffiness of the web and thereby increasing the air permeability and breathability of the non-woven fabric.

[0040] The preparation method of the polylactic acid-ethylene copolymer used in the present invention is based on the journal "Synthesis and Characterization of Novel Polyethylene-g-Polylactic Acid Graft Copolymer" (Cai Hao et al., Chemical Industry and Engineering, 1004-9533 (2022) 04-0022-08). The specific preparation steps are as follows:

[0041] (1) After mixing triisobutylaluminum and undecenol to obtain a mixed solution, toluene, ethylene, hexene and a zirconium catalyst are added to the mixed solution in sequence, and a reaction is carried out at 30° C. for 10 minutes to obtain an intermediate product;

[0042] (2) The intermediate product, the recrystallized L-lactide and MTBD (7-methyl hexacyclic bicyclic guanidine) were subjected to a secondary reaction at 50°C for 4 hours to obtain a reaction product. The reaction product was poured into ethanol and filtered. The filtered precipitate was washed with ethanol three times and dried at 70°C to obtain a polylactic acid-ethylene copolymer.

[0043] Wherein, in step (1), the molar ratio of triisobutylaluminum, undecenol and zirconium catalyst is 1:1:1:3×10 -6 In step (2), the ratio of the amount of the intermediate product, L-lactide and MTBD is 2:3:2×10 -4 .

[0044] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below with reference to specific embodiments.

[0045] The test materials used in the examples of the present invention are all conventional test materials in the field and can be purchased through commercial channels. Among them, potassium dihydrogen phosphate-disodium hydrogen phosphate solution was purchased from Yisejiu (Jiangsu Lianyungang) Biotechnology Co., Ltd.

[0046] Example 1: Preparation of degradable polylactic acid bicomponent spunbond nonwoven material

[0047] (1) Carboxymethyl starch, polyethylene, sodium trimetaphosphate and water were mixed in a mass ratio of 3:15:0.05:300, and the mixture was reacted at 80°C for 15 minutes, and then dried at 90°C for 30 minutes to obtain a reaction product; dopamine, potassium dihydrogen phosphate-disodium hydrogen phosphate solution and the reaction product were then mixed in an addition ratio of 0.2g:1L:0.2g, and the mixture was reacted for 20 hours to obtain a modified polyethylene;

[0048] (2) mixing low-melting-point PLA chips, modified polyethylene, polylactic acid-ethylene copolymer, and PLA-based compatibilizer masterbatch in a mass ratio of 85:10:4.93:0.07, heating and melting at 170-230° C., and extruding to granulate to obtain low-melting-point blended pellets;

[0049] (3) The low melting point blended pellets are used as the raw material for the skin layer and the spinning grade polylactic acid chips are used as the raw material for the core layer. The skin layer raw material and the core layer raw material are dried at 70°C for 12 hours, so that the moisture content of the skin layer raw material and the core layer raw material is ≤30ppm; the dried skin layer raw material is melt-extruded into a metering pump at 170-230°C through a screw extruder, and the dried core layer raw material is melt-extruded at 190-250°C, and the die head temperature is controlled at 228-236°C. The skin layer raw material and the core layer raw material are controlled. The mass ratio of the materials is 50:50. Side cold air cooling is carried out under a side-blown cooling airflow temperature of 25°C and a wind pressure of 250Pa. The filaments are drawn at a drawing pressure of 0.22MPa to obtain a sheath-core type two-component filament. The filaments are then pre-formed at a temperature of 70°C, heat-reinforced at a temperature of 125°C and a linear pressure of 65N / mm, and finally heat-set at 135°C and a circulating air opening of 45% to obtain a degradable polylactic acid two-component spunbond non-woven material.

[0050] Example 2: Preparation of degradable polylactic acid bicomponent spunbond nonwoven material

[0051] (1) Carboxymethyl starch, polyethylene, sodium trimetaphosphate and water were mixed in a mass ratio of 3:15:0.05:300, and the mixture was reacted at 80°C for 15 minutes, and then dried at 90°C for 30 minutes to obtain a reaction product; dopamine, potassium dihydrogen phosphate-disodium hydrogen phosphate solution and the reaction product were then mixed in an addition ratio of 0.2g:1L:0.2g, and the mixture was reacted for 20 hours to obtain a modified polyethylene;

[0052] (2) mixing low-melting-point PLA chips, modified polyethylene, polylactic acid-ethylene copolymer, and PLA-based compatibilizer masterbatch in a mass ratio of 85:10:4.93:0.07, heating and melting at 170-230° C., and extruding to granulate to obtain low-melting-point blended pellets;

[0053] (3) The low melting point blended pellets are used as the raw material for the skin layer and the spinning grade polylactic acid chips are used as the raw material for the core layer. The skin layer raw material and the core layer raw material are dried at 70°C for 12 hours to make the moisture content of the skin layer raw material and the core layer raw material ≤30ppm; the dried skin layer raw material is melt-extruded into a metering pump at 170-230°C through a screw extruder, and the dried core layer raw material is melt-extruded at 190-250°C, and the die head temperature is controlled at 228-236°C to control the moisture content of the skin layer raw material and the core layer raw material. The mass ratio is 30:70, and side cold air cooling is carried out under a side-blown cooling air flow temperature of 25°C and a wind pressure of 250Pa. The filaments are stretched at a stretching air pressure of 0.22MPa to obtain a sheath-core type two-component filament. The filaments are then pre-formed at a temperature of 60°C, heat-reinforced at a temperature of 145 / 145°C and a linear pressure of 95N / mm, and finally heat-set at 137°C and a circulating air opening of 35% to obtain a degradable polylactic acid two-component spunbond non-woven material.

[0054] Example 3: Preparation of degradable polylactic acid bicomponent spunbond nonwoven material

[0055] (1) Carboxymethyl starch, polyethylene, sodium trimetaphosphate and water were mixed in a mass ratio of 3:15:0.05:300, and the mixture was reacted at 80°C for 15 minutes, and then dried at 90°C for 30 minutes to obtain a reaction product; dopamine, potassium dihydrogen phosphate-disodium hydrogen phosphate solution and the reaction product were then mixed in an addition ratio of 0.2g:1L:0.2g, and the mixture was reacted for 20 hours to obtain a modified polyethylene;

[0056] (2) mixing low-melting-point PLA chips, modified polyethylene, polylactic acid-ethylene copolymer, and PLA-based compatibilizer masterbatch in a mass ratio of 85:10:4.93:0.07, heating and melting at 170-230° C., and extruding to granulate to obtain low-melting-point blended pellets;

[0057] (3) The low melting point blended pellets are used as the raw material for the skin layer and the spinning grade polylactic acid chips are used as the raw material for the core layer. The skin layer raw material and the core layer raw material are dried at 70°C for 12 hours to make the moisture content of the skin layer raw material and the core layer raw material ≤300ppm; the dried skin layer raw material is melt-extruded into a metering pump at 170-230°C, and the dried core layer raw material is melt-extruded into a metering pump at 190-250°C, and the mass ratio of the skin layer raw material to the core layer raw material is controlled to be The filaments were pre-formed at 45°C and heat-strengthened at 110°C and a linear pressure of 45 N / mm. Finally, the filaments were heat-set at 125°C and a circulating air pressure of 30% to obtain a biodegradable polylactic acid two-component spunbond nonwoven material.

[0058] Comparative Example 1:

[0059] The difference between this comparative example and Example 1 is that only the low-melting-point blended pellets prepared in step (2) of Example 1 are used as raw materials to prepare the polylactic acid single-component spunbond nonwoven material. The specific preparation method is as follows:

[0060] The raw materials were dried at 70° C. for 12 hours to make the moisture content of the raw materials ≤30 ppm; the dried raw materials were melt-extruded into a metering pump through a screw extruder at 170-230° C., the die head temperature was controlled at 228-236° C., and side cooling was performed under a side-blown cooling airflow temperature of 25° C. and an air pressure of 250 Pa. The filaments were drawn at a drawing air pressure of 0.22 MPa to obtain filaments, and then the filaments were pre-shaped at a temperature of 70° C., heat-consolidated at a temperature of 125° C. and a linear pressure of 65 N / mm, and finally heat-set at 135° C. and a circulating air opening of 45% to obtain a polylactic acid single-component spunbond nonwoven material.

[0061] Comparative Example 2:

[0062] The difference between this comparative example and Example 1 is that only spinning-grade polylactic acid chips are used as raw materials to prepare the polylactic acid single-component spunbond nonwoven material. The specific preparation method is as follows:

[0063] The raw materials were dried at 70° C. for 12 hours to make the moisture content of the raw materials ≤30 ppm; the dried raw materials were melt-extruded at 190-250° C., the die temperature was controlled at 228-236° C., and side cooling was performed under a side-blown cooling airflow temperature of 25° C. and an air pressure of 250 Pa. The filaments were drawn at a drawing air pressure of 0.22 MPa to obtain filaments, and then the filaments were pre-shaped at a temperature of 70° C., heat-consolidated at a temperature of 125° C. and a linear pressure of 65 N / mm, and finally heat-set at 135° C. and a circulating air opening of 45% to obtain a polylactic acid single-component spunbond nonwoven material.

[0064] Comparative Example 3:

[0065] The difference between this comparative example and Example 1 is that low melting point polylactic acid chips are used as the raw material for the skin layer and spinning grade polylactic acid chips are used as the raw material for the core layer. The specific preparation method is the same as step (3) of Example 1.

[0066] Comparative Example 4:

[0067] This comparative example differs from Example 1 in that carboxymethyl starch-modified polyethylene, low-melting-point polylactic acid chips, polylactic acid-ethylene copolymer, and compatibilizer masterbatch are used as raw materials to prepare low-melting-point blended pellets as the skin layer material, and spinning-grade PLA chips as the core layer material. The specific preparation method is the same as step (3) of Example 1.

[0068] Comparative Example 5:

[0069] This comparative example differs from Example 1 in that dopamine-modified polyethylene, low-melting-point polylactic acid chips, polylactic acid-ethylene copolymer, and compatibilizer masterbatch are used as raw materials to prepare low-melting-point blended pellets as the skin layer material, and spinning-grade PLA chips as the core layer material. The specific preparation method is the same as step (3) of Example 1.

[0070] The preparation method of carboxymethyl starch modified polyethylene is as follows:

[0071] Dopamine, potassium dihydrogen phosphate-disodium hydrogen phosphate solution and polyethylene were mixed in an addition ratio of 0.2 g:1 L:0.2 g, and a secondary reaction was carried out for 20 hours to modify the polyethylene with dopamine.

[0072] Test Example 1:

[0073] The spunbond nonwoven materials prepared in Examples 1-3 and Comparative Examples 1-5 were tested for grammage, thickness, tensile strength and elongation, air permeability and heat sealing strength. The results are shown in Table 1. Specifically:

[0074] The gram weight is in accordance with GB / T 24218.1-2009 “Textiles - Test methods for nonwovens - Part 1: Determination of mass per unit area”, and the sampling area is 10 cm × 10 cm;

[0075] The thickness is in accordance with GB / T 24218.2-2009 "Textiles - Nonwovens - Test Methods - Part 2: Determination of Thickness", where the presser foot area is 2000mm 2 , the pressing weight is 150cN;

[0076] The tensile strength and elongation were measured in accordance with GB / T 24218.2-2009 “Textiles—Nonwoven Fabrics—Test Methods—Part 3: Determination of Breaking Strength and Elongation (Strip Method)”, with a clamping distance of 100 mm and a tensile speed of 200 mm / min.

[0077] The air permeability is in accordance with GB / T 24218.2-2009 "Textiles - Nonwovens - Test Methods - Part 15: Determination of Air Permeability", the pressure difference is 200 Pa, and the area of the test sample is 20 cm 2 .

[0078] Heat seal strength refers to the force required to peel off the heat seal material per unit width at the heat seal layer. The method used in the test is the flat plate heat seal in the ordinary heat press sealing method. The data is the heat seal strength after the heat seal has cooled and stabilized.

[0079] The spunbond nonwoven materials prepared in Examples 1-3 and Comparative Examples 1-3 were tested for grammage, thickness, tensile strength and elongation, air permeability and heat sealing strength. The results are shown in Table 1.

[0080] Table 1

[0081] Group Weight thickness tensile strength Elongation Breathability Heat sealing strength Example 1 20 0.12 51 / 42 30 / 41 5683 12.6 Example 2 20 0.11 54 / 40 29 / 34 4663 9.6 Example 3 20 0.13 38 / 36 33 / 43 6032 4.6 Comparative Example 1 20 0.09 29 / 12 31 / 37 3900 8.4 Comparative Example 2 20 0.13 58 / 43 28 / 31 4100 3.1 Comparative Example 3 20 0.12 49 / 37 29 / 37 4400 9.1 Comparative Example 4 20 0.12 28 / 13 33 / 36 3760 8.9 Comparative Example 5 20 0.11 34 / 30 31 / 34 3916 8.2

[0082] As can be seen from Table 1, compared with the examples, the air permeability and heat sealing strength of the single-component nonwoven materials prepared in Comparative Examples 1-2 are poor. This shows that the air permeability and heat sealing performance of the bicomponent nonwoven materials are significantly improved compared to the single-component nonwoven materials. However, the bicomponent nonwoven material prepared in Comparative Example 3 uses only PLA slices. Compared with the examples, its tensile properties, air permeability, and heat sealing performance are all poor. This shows that adding modified polyethylene and polylactic acid-ethylene copolymer to the skin layer raw material can improve the tensile properties, air permeability, and heat sealing performance of the nonwoven materials. Compared with the examples, the tensile properties, air permeability, and heat sealing strength of Comparative Examples 4 and 5 are poor. This shows that modifying polyethylene with dopamine and carboxymethyl starch and using the modified polyethylene as the skin layer raw material can improve the tensile properties, air permeability, and heat sealing performance of the bicomponent nonwoven materials.

[0083] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the present application.

Claims

1. A method for preparing a polylactic acid two-component spunbond nonwoven material, characterized in that: The following steps are involved: (1) polyethylene, carboxymethyl starch, sodium trimetaphosphate and water are mixed, reacted once and dried to obtain a reaction product; the reaction product, dopamine and potassium dihydrogen phosphate-disodium hydrogen phosphate solution are then mixed, reacted twice to obtain modified polyethylene; (2) mixing low-melting-point PLA chips, modified polyethylene, polylactic acid-ethylene copolymer, and a compatibilizer, and heating and melting the mixture to obtain low-melting-point blended pellets; (3) Low melting point blended pellets are used as the raw material for the skin layer and spinning-grade polylactic acid chips are used as the raw material for the core layer. The polylactic acid two-component spunbond nonwoven material is prepared by the spunbond method.

2. The method for preparing the polylactic acid bicomponent spunbonded nonwoven material according to claim 1, wherein: In step (1), the mass ratio of carboxymethyl starch, polyethylene, sodium trimetaphosphate and water is (3-5): (15-20): (0.05-0.25): 300; the added amount ratio of dopamine, potassium dihydrogen phosphate-disodium hydrogen phosphate solution and reaction product is (0.2-0.8) g: 1 L: (0.2-0.8) g.

3. The method for preparing the polylactic acid bicomponent spunbonded nonwoven material according to claim 1, wherein: In step (1), the primary reaction temperature is 80-90° C., the reaction time is 15-25 min, and the secondary reaction time is 20-25 h.

4. The method for preparing the polylactic acid bicomponent spunbonded nonwoven material according to claim 1, wherein: In step (2), the mass ratio of low-melting-point PLA chips, modified polyethylene, polylactic acid-ethylene copolymer, and compatibilizer is (70-85): (5-10): (2-5): (0.005-0.1).

5. The method for preparing the polylactic acid bicomponent spunbonded nonwoven material according to claim 1, wherein: In step (2), the compatibilizer is one or more of polyolefin grafted maleic anhydride, glycidyl methacrylate, 4,4'-methylenebis(phenyl isocyanate), and PLA-based compatibilizer masterbatch.

6. The method for preparing the polylactic acid bicomponent spunbonded nonwoven material according to claim 1, wherein: In step (2), the heating and melting temperature is 170-230°C.

7. The method for preparing the polylactic acid bicomponent spunbonded nonwoven material according to claim 1, wherein: In step (3), the mass ratio of the skin layer raw material to the core layer raw material is (2-8): (2-8).

8. The polylactic acid bicomponent spunbonded nonwoven material prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the polylactic acid two-component spunbonded nonwoven material according to claim 8 in the preparation of filtration products and food packaging products.