Polylactic acid superfine fiber composite material capable of preventing accumulation and rolling and preparation method of polylactic acid superfine fiber composite material

Abstract

The invention belongs to the technical field of non-woven materials, discloses an anti-accumulation and anti-tumble polylactic acid superfine fiber composite material and a preparation method thereof, and aims to solve the technical problems of liquid accumulation and poor mechanical properties of non-woven materials. The preparation method comprises the following steps: (1) preparing a polylactic acid superfine fiber net with a highly oriented arrangement structure by taking a degradable polymer polylactic acid as a raw material and adopting a melt-blowing in-situ drafting technology; and (2) sequentially stacking the highly oriented polylactic acid superfine fiber net and the cotton woven fabric along the thickness direction, and carrying out composite molding by adopting a spunlace technology to obtain the polylactic acid superfine fiber composite material with the linear embedded structure. The PLA fibers and the cotton fibers on the lower layer are mutually entangled in the water jet direction to form an ordered coarse structure with the adjustable number of embedded fibers, the asymmetric liquid tumbling capacity and the mechanical strength of the PLA superfine fiber composite material are remarkably improved, and the PLA superfine fiber composite material has huge application potential in the field of personal protection equipment.

Description

Technical Field

[0001] The invention relates to the technical field of nonwoven materials, and in particular to a polylactic acid ultrafine fiber composite material. Background Art

[0002] Personal protective equipment (PPE), such as chemical protective clothing, medical protective clothing, and masks, plays a vital role in blocking the spread of pollutants and provides basic protection for the human body against harmful substances, including liquids, particulate matter, and viruses. Traditional PPE mainly relies on petroleum-based microfiber fabrics, such as polypropylene (PP), polyethylene (PE), and polyester (PET). This is because the microfiber structure has dense pores and randomly arranged fibers, which can effectively resist liquid penetration. However, petroleum-based microfiber fabrics are not degradable in the natural environment. Therefore, there is an urgent need to develop degradable microfiber fabrics for functional PPE. Polylactic acid (PLA) has attracted widespread attention in the application of degradable PPE due to its excellent biodegradability. However, pure PLA fiber materials show strong adhesion to liquids, which brings significant defects in practical applications—namely, the accumulation of liquid pollutants, leading to secondary pollution. In addition, the limited mechanical strength of pure PLA fiber materials makes it unsuitable for use alone in PPE that requires comfort and durability. Therefore, there is an urgent need to develop PLA fiber materials with enhanced liquid sliding properties and high mechanical strength for use in high-performance PPE.

[0003] At present, the research focus is on improving the waterproof performance of PLA microfiber fabrics, thereby achieving comprehensive performance improvement, including organic or inorganic hybridization and layered structure design. Yu et al. incorporated hydrophobic polydimethylsiloxane (PDMS) into PLA spinning solution through electrospinning technology and developed a polydimethylsiloxane / polylactic acid fiber material with a water contact angle of 155.1°. Li et al. combined PLA with polypropylene (PP) and silicon dioxide (SiO 2 ) were physically blended to prepare a microfiber material with high water resistance and excellent self-cleaning properties. Hou et al. used polyvinyl butyral to prepare a multi-layer dense PLA microfiber fabric, which significantly improved its water resistance. These studies have shown that the physical blending of low surface energy inorganic or organic materials and structural regulation through multi-layer design have a significant effect on liquid barrier properties. However, these methods face challenges such as low production efficiency, complex preparation process and unstable structure in actual large-scale applications, and are often limited to laboratory research. Summary of the invention

[0004] In view of the above technical problems, the present invention proposes a polylactic acid ultrafine fiber composite material that prevents accumulation and rolls off and a preparation method thereof. The polylactic acid ultrafine fiber composite material of the present invention presents a linear embedded structure, and an ordered rough structure with an adjustable number of embedded fibers is formed by entanglement of PLA fibers with the lower cotton fibers along the direction of the water jet, thereby significantly improving the asymmetric liquid rolling ability and mechanical strength of the PLA ultrafine fiber composite material.

[0005] To achieve the above object, the technical solution of the present invention is implemented as follows:

[0006] The preparation method of the anti-agglomeration and easy-to-roll polylactic acid ultrafine fiber composite material comprises the following steps:

[0007] (1) Silicon dioxide (SiO 2 ) was added to the paraffin (PW) melt and mixed, and PW@SiO was obtained after cooling. 2 blends;

[0008] (2) PW@SiO prepared in step (1) 2 The blend is mixed with polylactic acid, and a highly oriented PLA ultrafine fiber web is prepared by melt-blowing, web-forming and secondary drawing;

[0009] (3) The highly oriented PLA ultrafine fiber web obtained in step (2) is stacked with the cotton woven fabric in the thickness direction, and a PLA ultrafine fiber composite material, i.e., a linear embedded polylactic acid ultrafine fiber composite material, is obtained by a hydroentanglement reinforcement process.

[0010] The particle size of silicon dioxide in the above step (1) is 1-3 μm and the density is 2.2 g / cm 3 .

[0011] In the above step (2), PLA, PW@SiO 2 The mass ratio of polylactic acid, paraffin wax and silicon dioxide in the blend is (94-96.4):3:(0.6-3).

[0012] The process parameters of meltblowing in the above step (2) are: the temperature of zone 1 of the screw extruder is 170-190°C, the temperature of zone 2 is 200-220°C, the temperature of zone 3 is 220-240°C, the die head temperature is 220-240°C, the hot air temperature is 240-260°C, the hot air pressure is 33-41 kPa, and the receiving distance of the receiving mesh curtain in the meltblowing experimental equipment is 15-20 cm.

[0013] The drafting ratio of the secondary drafting in the above step (2) is 1.5-3.0.

[0014] During the water stab reinforcement process in step (3), the water stab energy is 1410.9-4703.2 kJ / m 2 .

[0015] The surface density of the cotton woven fabric in the above step (3) is 60g / m 2 .

[0016] The linear embedded polylactic acid ultrafine fiber composite material is prepared by the above-mentioned preparation method.

[0017] Furthermore, the modal pore size of the linear embedded polylactic acid ultrafine fiber protective material is 19-48 μm, the porosity is 47-79%, the water contact angle is 139-164°; the breaking strength is 298.3-391.5N, and the bursting strength is from 259.7 to 379.4N.

[0018] The above-mentioned anti-accumulation and easy-to-roll-off polylactic acid ultrafine fiber composite material is used in the field of packaging materials or medical protection.

[0019] The beneficial effects produced by the present invention are:

[0020] (1) The present invention designs and develops a polylactic acid ultrafine fiber composite material that is anti-accumulation and easy to roll off, presenting a linear embedded structure. It is composed of highly oriented PLA ultrafine fiber material and cotton woven cloth. Under the action of high-pressure water jet, PLA fibers are entangled with the lower cotton fibers along the direction of the water jet to form an ordered rough structure with adjustable fiber embedding amount, which gives the PLA ultrafine fiber composite material excellent liquid rolling ability. Specifically, through process adjustment, the number of linearly embedded PLA fibers is 1485, the porosity is 49.3%, and the modal pore size is 19.5μm. In addition, the PLA ultrafine fiber composite material exhibits excellent asymmetric liquid easy rolling ability, the minimum distilled water rolling angle reaches 12°, and the difference in longitudinal and lateral rolling angles can reach up to 26°.

[0021] (2) Through the inorganic-organic small molecule composite technology, on the one hand, the problem of poor crystallization performance of PLA was improved, and on the other hand, low surface energy modification of PLA was achieved, giving the material excellent liquid shielding ability, among which the water contact angle can be as high as 164°, and the synthetic blood contact angle is also maintained above 130°.

[0022] (3) Compared with traditional PP meltblown fiber materials, PLA ultrafine fiber composites showed enhanced mechanical properties, with the bursting strength increased from 259.7N to 379.4N and the longitudinal breaking strength increased to 325.9N, achieving a strength increase of about 10.1 times, demonstrating the robustness of PLA ultrafine fiber composites in practical PPE applications. At the same time, as the water injection energy increased from 1410.9kJ / m 2 Increased to 4703.2 kJ / m 2The sample showed excellent waterproof and breathable performance. The hydrostatic pressure resistance value increased from 2398Pa to 4379Pa. The air permeability and water vapor decreased to a certain extent, but still remained at 78.9mm / s and 4802.6g / (m 2 ·24h).

[0023] (4) The present invention proposes a linear embedded PLA ultrafine fiber composite material with easy liquid rolling off characteristics and excellent mechanical strength, which has great application potential in the field of personal protective equipment. In addition, its preparation method is simple and can be mass-produced, providing a promising environmentally friendly solution for improving the liquid management ability in personal protective materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 Schematic diagram of the process principle of anti-accumulation and anti-rolling polylactic acid ultrafine fiber composite material: (a) meltblowing process; (b) hydroentanglement process; (c) schematic diagram of linear embedding structure; (d) actual sample picture.

[0026] Figure 2 Linear embedded morphology of PLA ultrafine fiber composites: Surface and cross-sectional scanning electron microscope (SEM) images of samples prepared at different spunlacing energies: (a, d) 1410.9 kJ / m 2 ,(b,e)2105.9kJ / m 2 ,(c,f)4703.2kJ / m 2 ; (g) Orientation angle distribution curve of the sample prepared under a hot air pressure of 41 kPa; The number of PLA fibers embedded in the sample: (h) different water spunlace energy, (i) different hot air pressure.

[0027] Figure 3 Structural characteristic parameters of PLA ultrafine fiber composite materials: fiber diameter distribution curve (a. different hydroentanglement energy, d. different hot air pressure); pore size distribution curve (b. different hydroentanglement energy, e. different hot air pressure); thickness-porosity change curve (c. different hydroentanglement energy, f. different hot air pressure).

[0028] Figure 4Figure 2 shows the liquid penetration resistance of PLA ultrafine fiber composites: (a) actual pictures of different liquids; contact angles of different types of liquids on samples prepared under different hot air pressures: (b) liquid droplet contact angle (LCA) in the longitudinal direction (MD), (c) liquid droplet contact angle (LCA) in the transverse direction (CD); contact angles of different types of liquids on samples treated under different hydroentanglement energies: (d) liquid droplet contact angle (LCA) in the longitudinal direction (MD), (e) liquid droplet contact angle (LCA) in the transverse direction (CD); images of different liquid contact angles: (f) longitudinal direction (MD), (g) transverse direction (CD); (h) infrared spectrum image of the sample; hydrostatic pressure resistance curves: (i) different hot air pressures, (j) different hydroentanglement energies.

[0029] Figure 5 Liquid rolling characteristics of PLA microfiber composites: contact angle change curve of the sample: (a) longitudinal (MD), (b) transverse (CD), and photos of the rolling process (c1) longitudinal (MD), (c2) transverse (CD); (d) tilt angle of different volumes of distilled water; tilt angle of different types of liquids on the sample surface under different hot air pressures: (e) longitudinal (MD), (f) transverse (CD); tilt angle of different types of liquids on the sample surface under different water entanglement energies: (g) longitudinal (MD), (h) transverse (CD); dyeing water spray test image (i1), photos of the PLA side after the test (i2) and cotton fiber side (i3).

[0030] Figure 6 Mechanical properties of PLA ultrafine fiber composites: force-displacement curves (a-longitudinal MD, b-transverse CD) and bursting curves (c) of samples prepared under different spunlacement energies; (d) force-displacement curves of different types of nonwoven materials; spunlacement energy is 2105.9 kJ / m 2 The tensile fracture process of the sample in the longitudinal direction MD (e) and transverse direction CD (f).

[0031] Figure 7 Breathable and comfortable performance of PLA microfiber composites: air permeability and water vapor permeability curves of samples prepared under different hot air pressures (a) and hydroentanglement energies (b); photos of the water evaporation experiment process (d) and height-time change curves (c); softness curves of samples under different hot air pressures (e) and hydroentanglement energies (f).

[0032] Figure 8Actual rolling application of PLA microfiber composite samples: (a) Photo of 30 μL distilled water rolling on the sample surface; (b) sludge self-cleaning test of the sample, (c) synthetic blood self-cleaning test; (d) practical application in medical packaging materials and liquid rolling demonstration; (e) water spraying demonstration of PLA microfiber composite samples and cotton protective lab coats. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in 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 creative work are within the scope of protection of the present invention.

[0034] Experimental Materials

[0035] Polylactic acid: Grade 6252D, white granules, melt flow index 21.3g / 10min (210℃), density 1.24g / cm 3 , (NatureWorks, USA). Paraffin wax: brand 58#, white granules, melting point 58°C, (Zhengzhou Jiajie Chemical Products Co., Ltd., China). Silicon dioxide: white powder, particle size 1-3 μm, density 2.2 g / cm 3 , (Jinan Zhiding Co., Ltd., China). Cotton woven fabric: thickness 450mm, weight 60g / m 2 (Hebei Yongsheng Cotton Mill, China).

[0036] Example 1

[0037] The preparation method of the anti-agglomeration and easy-to-roll polylactic acid ultrafine fiber composite material of this embodiment comprises the following steps:

[0038] (1) Melt-blown in-situ drawing preparation of highly oriented PLA ultrafine fiber materials

[0039] First, PLA slices were dried in a vacuum oven at 80 °C for 8 h; then PW slices were softened and melted in a water bath at 90 °C to form a PW melt, and SiO 2 The powder was mixed evenly with a high-speed stirrer to obtain PW@SiO 2 Blended melt (PW and SiO 2 The mass ratio of the blended melt was 5:3), and the blended melt was cooled to room temperature and mixed with PLA slices (PW@SiO 2 The ratio of PLA chips was 4.8:95.2) and then fed into the melt-blown experimental system, and softened and melted by the screw extruder to form PLA / PW@SiO 2The melt is blended and quantitatively delivered to the meltblowing die head, and then thinned into fibers under the heat and pressure of the hot air flow and deposited on the receiving mesh curtain to form a PLA ultrafine fiber web with different fiber fineness. Finally, the fiber web is secondary stretched under the winding tension to cause the fibers to rearrange in the longitudinal direction to form a highly oriented PLA ultrafine fiber material with a stretch ratio of 3.0. The preparation process is as follows Figure 1 a and the main meltblowing process parameters are shown in Table 1.

[0040] Table 1 Main process parameters of meltblowing

[0041]

[0042] (2) Preparation of linear embedded PLA microfiber composites by hydroentanglement

[0043] The highly oriented PLA microfiber material and the cotton woven fabric were stacked in sequence along the thickness direction, and the stacked fiber webs were hydroentangled using a hydroentanglement system (SC-600, Changzhou Xinrenli Textile Equipment Co., Ltd.). Figure 1 As shown in Figure 2b. Under the dual effects of the impact force and shear force of the high-pressure water jet, the fibers are displaced and rearranged along the direction of the water jet, forming a more orderly longitudinal arrangement structure. Subsequently, some PLA fibers move downward and entangle with the cotton fibers in the lower layer, causing the PLA fibers to gradually embed into the cotton fiber layer, forming a linear embedded structure ( Figure 1 c), and the anti-agglomeration and easy-to-roll-off polylactic acid ultrafine fiber composite material is obtained. Figure 1 As shown in d, the prepared linear embedded structure of PLA ultrafine fiber composite material appears white on a macro scale, demonstrating its potential for large-scale production. 2 .

[0044] In order to explore the influence of hot air pressure on the performance of composite materials, a series of hot air pressures (33kpa, 35kpa, 37kpa, 39kpa, 41kpa) were set for performance investigation.

[0045] Example 2

[0046] The preparation method of the anti-agglomeration and easy-to-roll polylactic acid ultrafine fiber composite material of this embodiment comprises the following steps:

[0047] (1) Melt-blown in-situ drawing preparation of highly oriented PLA ultrafine fiber materials

[0048] First, PLA slices were dried in a vacuum oven at 80 °C for 8 h; then PW slices were softened and melted in a water bath at 90 °C to form a PW melt, and SiO 2 The powder was mixed evenly with a high-speed stirrer to obtain PW@SiO 2Blended melt (PW and SiO 2 The mass ratio of the blended melt was 5:3), and the blended melt was cooled to room temperature and mixed with PLA slices (PW@SiO 2 The ratio of PLA chips was 4.8:95.2) and then fed into the melt-blown experimental system, and softened and melted by the screw extruder to form PLA / PW@SiO 2 The melt is blended and quantitatively delivered to the meltblowing die head, and then thinned into fibers under the heat and pressure of the hot air flow and deposited on the receiving mesh curtain to form a PLA ultrafine fiber web with different fiber fineness. Finally, the fiber web is secondary drawn under the winding tension to cause the fibers to be rearranged in the longitudinal direction to form a highly oriented PLA ultrafine fiber material with a draw ratio of 3.0. The main meltblowing process parameters are shown in Table 2.

[0049] Table 2 Main process parameters of meltblowing

[0050]

[0051]

[0052] (2) Preparation of linear embedded PLA microfiber composites by hydroentanglement

[0053] The highly oriented PLA ultrafine fiber material and cotton woven fabric were stacked in sequence along the thickness direction, and the stacked fiber webs were hydroentangled using a hydroentanglement system (SC-600, Changzhou Xinrenli Textile Equipment Co., Ltd.). Under the dual effects of the impact force and shear force of the high-pressure water jet, the fibers were displaced and rearranged along the direction of the water jet to form a more orderly longitudinal arrangement structure. Subsequently, some PLA fibers moved downward and entangled with the lower cotton fibers, causing the PLA fibers to gradually embed into the cotton fiber layer to form a linear embedded structure, thus obtaining an anti-agglomeration and anti-rolling polylactic acid ultrafine fiber composite material. In order to explore the effect of water needle energy on the performance of the composite material, a series of water needle energies (1410.9 kJ / m 2 、1699.3kJ / m 2 、2105.9kJ / m 2 、2821.9kJ / m 2 、4703.2kJ / m 2 ) to explore performance.

[0054] Example 3

[0055] The preparation method of the anti-agglomeration and easy-to-roll polylactic acid ultrafine fiber composite material of this embodiment comprises the following steps:

[0056] (1) Melt-blown in-situ drawing preparation of highly oriented PLA ultrafine fiber materials

[0057] First, PLA slices were dried in a vacuum oven at 80 °C for 8 h; then PW slices were softened and melted in a water bath at 90 °C to form a PW melt, and SiO 2 The powder was mixed evenly with a high-speed stirrer to obtain PW@SiO 2 Blended melt (PW and SiO 2 The mass ratio of PW@SiO 2 The ratio of PLA chips was 4.2:95.8) and then fed into the melt-blown experimental system, and softened and melted by the screw extruder to form PLA / PW@SiO 2 The blended melt is quantitatively delivered to the meltblowing die head, and then thinned into fibers under the heat and pressure of the hot air flow and deposited on the receiving mesh curtain to form a PLA ultrafine fiber web with different fiber fineness. Finally, the secondary drawing of the fiber web under the winding tension causes the fibers to be rearranged in the longitudinal direction to form a highly oriented PLA ultrafine fiber material with a drawing ratio of 3.0. The main meltblowing process parameters are shown in Table 3.

[0058] Table 3 Main process parameters of meltblowing

[0059]

[0060]

[0061] (2) Preparation of linear embedded PLA microfiber composites by hydroentanglement

[0062] The highly oriented PLA ultrafine fiber material and cotton woven fabric are stacked in sequence along the thickness direction, and the stacked fiber webs are hydroentangled using a hydroentanglement system (SC-600, Changzhou Xinrenli Textile Equipment Co., Ltd.). Under the dual effects of the impact force and shear force of the high-pressure water jet, the fibers are displaced and rearranged along the direction of the water jet to form a more orderly longitudinal arrangement structure. Subsequently, some PLA fibers move downward and entangle with the lower cotton fibers, causing the PLA fibers to gradually embed into the cotton fiber layer to form a linear embedded structure, thus obtaining an anti-agglomeration and anti-rolling polylactic acid ultrafine fiber composite material. Among them, the water needle energy is 2105.9kJ / m 2 .

[0063] Example 4

[0064] The preparation method of the anti-agglomeration and easy-to-roll polylactic acid ultrafine fiber composite material of this embodiment comprises the following steps:

[0065] (1) Melt-blown in-situ drawing preparation of highly oriented PLA ultrafine fiber materials

[0066] First, PLA slices were dried in a vacuum oven at 80 °C for 8 h; then PW slices were softened and melted in a water bath at 90 °C to form a PW melt, and SiO 2 The powder was mixed evenly with a high-speed stirrer to obtain PW@SiO 2 Blended melt (PW and SiO 2 The mass ratio of PW@SiO 2 The ratio of PLA chips was 3.6:96.4) and then fed into the melt-blown experimental system, and softened and melted by the screw extruder to form PLA / PW@SiO 2 The melt is blended and quantitatively delivered to the meltblowing die head, and then thinned into fibers under the heat and pressure of the hot air flow and deposited on the receiving mesh curtain to form a PLA ultrafine fiber web with different fiber fineness. Finally, the secondary drawing of the fiber web under the winding tension causes the fibers to be rearranged in the longitudinal direction to form a highly oriented PLA ultrafine fiber material with a drawing ratio of 1.5. The main meltblowing process parameters are shown in Table 4.

[0067] Table 4 Main process parameters of meltblowing

[0068]

[0069] (2) Preparation of linear embedded PLA microfiber composites by hydroentanglement

[0070] The highly oriented PLA ultrafine fiber material and cotton woven fabric are stacked in sequence along the thickness direction, and the stacked fiber webs are hydroentangled using a hydroentanglement system (SC-600, Changzhou Xinrenli Textile Equipment Co., Ltd.). Under the dual effects of the impact force and shear force of the high-pressure water jet, the fibers are displaced and rearranged along the direction of the water jet to form a more orderly longitudinal arrangement structure. Subsequently, some PLA fibers move downward and entangle with the lower cotton fibers, causing the PLA fibers to gradually embed into the cotton fiber layer to form a linear embedded structure, thus obtaining an anti-agglomeration and anti-rolling polylactic acid ultrafine fiber composite material. Among them, the water needle energy is 2105.9kJ / m 2 .

[0071] Example 5

[0072] The preparation method of the anti-agglomeration and easy-to-roll polylactic acid ultrafine fiber composite material of this embodiment comprises the following steps:

[0073] (1) Melt-blown in-situ drawing preparation of highly oriented PLA ultrafine fiber materials

[0074] First, PLA slices were dried in a vacuum oven at 80 °C for 8 h; then PW slices were softened and melted in a water bath at 90 °C to form a PW melt, and SiO 2The powder was mixed evenly with a high-speed stirrer to obtain PW@SiO 2 Blended melt (PW and SiO 2 The mass ratio of PW@SiO 2 The ratio of PLA chips was 5.4:94.6) and then fed into the melt-blown experimental system, and softened and melted by the screw extruder to form PLA / PW@SiO 2 The melt is blended and quantitatively delivered to the meltblowing die head, and then thinned into fibers under the heat and pressure of the hot air flow and deposited on the receiving mesh curtain to form a PLA ultrafine fiber web with different fiber fineness. Finally, the fiber web is secondary drawn under the winding tension to cause the fibers to be rearranged in the longitudinal direction to form a highly oriented PLA ultrafine fiber material with a draw ratio of 3. The main meltblowing process parameters are shown in Table 5.

[0075] Table 5 Main process parameters of meltblowing

[0076]

[0077] (2) Preparation of linear embedded PLA microfiber composites by hydroentanglement

[0078] The highly oriented PLA ultrafine fiber material and cotton woven fabric are stacked in sequence along the thickness direction, and the stacked fiber webs are hydroentangled using a hydroentanglement system (SC-600, Changzhou Xinrenli Textile Equipment Co., Ltd.). Under the dual effects of the impact force and shear force of the high-pressure water jet, the fibers are displaced and rearranged along the direction of the water jet to form a more orderly longitudinal arrangement structure. Subsequently, some PLA fibers move downward and entangle with the lower cotton fibers, causing the PLA fibers to gradually embed into the cotton fiber layer to form a linear embedded structure, thus obtaining an anti-agglomeration and anti-rolling polylactic acid ultrafine fiber composite material. Among them, the water needle energy is 2105.9kJ / m 2 .

[0079] Example 6

[0080] The preparation method of the anti-agglomeration and easy-to-roll polylactic acid ultrafine fiber composite material of this embodiment comprises the following steps:

[0081] (1) Melt-blown in-situ drawing preparation of highly oriented PLA ultrafine fiber materials

[0082] First, PLA slices were dried in a vacuum oven at 80 °C for 8 h; then PW slices were softened and melted in a water bath at 90 °C to form a PW melt, and SiO 2 The powder was mixed evenly with a high-speed stirrer to obtain PW@SiO 2 Blended melt (PW and SiO 2The mass ratio of PW@SiO 2 The ratio of PLA chips was 6:94) and then fed into the melt-blown experimental system, and softened and melted by the screw extruder to form PLA / PW@SiO 2 The melts are blended and quantitatively delivered to the melt-blowing die head, and then thinned into fibers under the heat and pressure of the hot air flow and deposited on the receiving mesh curtain to form a PLA ultrafine fiber web with different fiber finenesses. Finally, the fiber web is secondary drawn under the winding tension to cause the fibers to be rearranged in the longitudinal direction to form a highly oriented PLA ultrafine fiber material with a drawing ratio of 3. The main melt-blowing process parameters are the same as those in Example 5.

[0083] (2) Preparation of linear embedded PLA microfiber composites by hydroentanglement

[0084] The highly oriented PLA ultrafine fiber material and cotton woven fabric are stacked in sequence along the thickness direction, and the stacked fiber webs are hydroentangled using a hydroentanglement system (SC-600, Changzhou Xinrenli Textile Equipment Co., Ltd.). Under the dual effects of the impact force and shear force of the high-pressure water jet, the fibers are displaced and rearranged along the direction of the water jet to form a more orderly longitudinal arrangement structure. Subsequently, some PLA fibers move downward and entangle with the lower cotton fibers, causing the PLA fibers to gradually embed into the cotton fiber layer to form a linear embedded structure, thus obtaining an anti-agglomeration and anti-rolling polylactic acid ultrafine fiber composite material. Among them, the water needle energy is 2105.9kJ / m 2 .

[0085] Implementation effect example

[0086] The anti-agglomeration and anti-rolling polylactic acid ultrafine fiber composite material prepared in Example 1-2 was used to explore the effect of water needle energy on the performance of the composite material during hot air pressure and water spunlace reinforcement. The characteristic indicators of the composite material were tested by the following method, and the specific test methods and results are as follows:

[0087] (1) Morphology and structure test

[0088] The JSM-IT 200 scanning electron microscope (JEOL, Japan) was used to observe the surface and cross-sectional morphology of the samples and take electron microscope pictures. The fiber orientation angle and diameter of the electron microscope pictures were analyzed using the OrientationJ plugin (ImageJ, National Institutes of Health) and Smile View Map software (JEOL, Japan). Before the test, the samples were gold-plated using an SBC-12 ion sputtering instrument (Beijing Haifuda Technology Co., Ltd.).

[0089] The arrangement structure of the fiber material is crucial to its liquid rolling properties. Scanning electron microscope (SEM) image ( Figure 2 a-2f) show the cross-section and surface of the PLA microfiber composite with linear embedded structure. Figure 2 a-2c shows that the water injection energy is 1410.9 kJ / m 2 、2105.9kJ / m 2 and 4703.2 kJ / m 2 The cross-sectional structure of the sample shows that the upper PLA fiber and the lower cotton fiber are tightly inlaid through the hydroentanglement process. Figure 2 a and Figure 2 c It was also found that with the increase of water needle energy, the entanglement between PLA fiber and cotton fiber became tighter. Comparing the surface structure of the samples ( Figure 2 d-2g) It was found that under the action of the high-pressure water jet, some of the highly oriented PLA ultrafine fiber materials with an orientation angle distribution range of -30° to 30° and a frequency of 58.4% moved downward and entangled with the cotton fibers to form an air groove structure arranged along the direction of the water jet. As the energy of the water jet increases, the number of PLA fibers moving downward gradually increases, and the linear embedded structure formed is significantly enhanced. Based on the Cassie theory, it can be seen that the air grooves formed by this linear embedded structure form an air cushion structure between the liquid and the sample surface, which effectively reduces the contact area of ​​the liquid and reduces its adhesion, thereby improving the waterproof ability of the sample and providing more transmission channels for the liquid to roll off the sample surface. At the same time, by analyzing the roughness of the electron microscope image of the sample surface and calculating the number of PLA fibers embedded in the cotton fiber layer, the relationship curve between the embedding degree and the water jet energy and hot air pressure is obtained. The results are shown in the figure. Figure 2 As shown in h-2i. As the water needle energy increases from 1410.9kJ / m 2 Increased to 4703.2 kJ / m 2 , the number of embedded PLA fibers increased from 532 to 1485. In addition, the fiber fineness structure with obvious differences brought by different hot air pressures also has a certain impact on the linear embedding structure. As the hot air pressure increases to 41kPa, the number of embedded fibers increases from 512 to 1215. This is because when the fiber diameter decreases, the number of fibers per unit area gradually increases, and the impact of high-energy water jets will drive more PLA fibers to move downward, thereby forming a denser linear entanglement between the two layers of fibers.

[0090] (2) Characteristic performance test

[0091] The disc sampler was used to obtain an area of ​​100 cm 2 The samples were weighed using a JA1003 electronic balance (Shanghai Bowen Instrument Co., Ltd.).

[0092] Thickness: The thickness of the sample was tested at five random locations using a fabric thickness meter (32CHF1030, Shengtaixin Electronic Technology Co., Ltd., Deqing, China).

[0093] Pore ​​size: The pore size distribution was tested by the bubble point method using a PSM 165H pore size analyzer (Topas, Germany). The test sample was a circle with a diameter of 2 cm, the test liquid was Topar, the surface tension was 16.0 mN / m, and the air pressure was 4 bar.

[0094] Porosity: Calculated using the mass density method using formula (1).

[0095] n=(1-m / pδ) (1)

[0096] Where n-porosity, %; p-density, g / m 3 ; m-mass per unit area, g / m 2 ;δ-thickness, m.

[0097] from Figure 3 a-3f show that the linear embedded structure prepared by meltblowing-hydroentanglement composite process has a significant effect on the fiber diameter and pore size of PLA ultrafine fiber composite samples. 2 When the water injection energy increases to 4703.2 kJ / m 2 When the modal pore size is reduced to 19.5μm, the thickness and porosity are reduced to 0.82mm and 49.3%, respectively. This is because the enhanced impact of high-energy water jets will cause the displacement of PLA fibers to increase, the entanglement between the two layers of fibers to increase, and the pore structure between the fibers to decrease. In addition, Figure 3 d-3f shows the influence of linear embedded structure on hot air pressure samples. As the hot air pressure of the sample increases from 33 kPa to 41 kPa, the average fiber diameter decreases from 3.9 μm to 1.3 μm, and the modal pore size and porosity decrease from 47.5 μm and 78.3% to 21.2 μm and 47.5%, respectively.

[0098] (3) Contact angle, rolling angle test and water dipping test

[0099] The water contact angle and rolling angle of the samples were tested using an SDC-350 liquid contact angle meter (Dongguan Shengding Precision Instrument Co., Ltd.). The water contact angle and rolling angle test liquids were distilled water, synthetic blood, and coffee. The water contact angle test liquid volume was 3 μL, and the rolling angle test liquid volume was 10 μL, 20 μL, 30 μL, 40 μL, and 50 μL.

[0100] The YM-13 fabric surface water stain tester (Laizhou Yuanmao Instrument Co., Ltd.) was used to test the water stain level of the sample. The test liquid was 100 mL of distilled water dyed with reactive brilliant blue.

[0101] Figure 4 a shows the optical photograph of artificial sweat, synthetic blood, milk, distilled water and coffee on the sample surface at a hot air pressure of 41 kPa. The different types of liquids are all spherical and do not penetrate the interior of the sample. Subsequently, the vertical and horizontal static contact angles of 3 μL distilled water, synthetic blood and coffee on the sample surface were further tested. The results are shown in Figure 4 As shown in b-4g, it can be seen from the figure that the longitudinal and transverse liquid contact angles of different PLA ultrafine fiber composite samples are all higher than 130°, indicating that the samples have excellent resistance to liquid penetration. Figure 4 b-4c shows that with the increase of hot air pressure of PLA microfiber material, the longitudinal and transverse liquid contact angles of PLA microfiber composite material samples both show an increasing trend. Specifically, when the hot air pressure is 33kPa, the longitudinal contact angles of distilled water, synthetic blood and coffee of the sample are 138.9°, 132.1° and 135°, respectively. As the hot air pressure increases to 41kPa, the longitudinal contact angles of the liquid increase to 154.4°, 153.2° and 153.4°, respectively, increasing by 11.2%, 16.0% and 13.6%, respectively. Correspondingly, the transverse contact angles of distilled water, synthetic blood and coffee increase from 140.1°, 133.7° and 140.0° to 163.7°, 159.4° and 161.0°, respectively, increasing by 16.8%, 19.2% and 15.0%, respectively. This phenomenon is mainly because as the hot air pressure increases, the fiber fineness gradually decreases, and the PLA fiber and cotton fiber are more tightly entangled, which reduces the porosity and has efficient liquid shielding ability.

[0102] In addition, different water injection energies also have a positive effect on the liquid shielding ability of the sample. Figure 4 d-4e shows the vertical and horizontal contact angles of distilled water, synthetic blood and coffee. 2 Increased to 4703.2 kJ / m 2 , the longitudinal contact angles of different liquids increased from 138.7°, 132.7° and 135.6° to 155.2°, 154.7° and 154.1°, respectively, and the transverse contact angles increased from 141.3°, 137.0° and 140.1° to 162.4°, 159.9° and 161.3°, respectively. The contact angles of different types of liquids also have certain differences, that is, the longitudinal and transverse contact angles of distilled water are always higher than those of the other two types of liquids: the water needle energy is 2821.9 kJ / m 2The longitudinal contact angles of the distilled water, synthetic blood and coffee of the samples were 151.7°, 148.9° and 150.2°, respectively, and the transverse contact angles were 155.7°, 151.5° and 153.7°, respectively. This phenomenon is because the surface tension values ​​of distilled water, synthetic blood and coffee used in the synthetic blood experiment were 72.8mN / m, 42mN / m and 52mN / m, respectively. Based on Young's equation gas-liquid-solid three-phase interface theory, high surface tension liquids will form a larger contact angle on the surface of hydrophobic fabrics, exhibiting better waterproof performance.

[0103] Figure 4 h shows the infrared spectrum experimental analysis results of PLA ultrafine fiber composite samples. Pure PLA ultrafine fiber material has an infrared spectrum of 1751.41 cm -1 、1184.48cm -1 and 1084.83cm -1 They are C=O stretching vibration peak, COC stretching vibration peak and CO stretching vibration peak. 2 The addition of PW and SiO 2 The modified blend polymer has more hydrophobic groups, and the hydrophobic properties of the PLA microfiber composites are enhanced.

[0104] Figure 5 a-5c shows the dynamic rolling process of 30 μL distilled water on the surface of PLA microfiber composite sample. Figure 5 a and 5c1 found that when the test bench was not tilted, the front and rear contact angles of 30 μL of distilled water dropped on the longitudinal surface of the PLA microfiber composite material were 138° and 139° respectively, indicating that the sample has high efficiency in resisting liquid penetration; as the sample tilt angle increases to 10°, the liquid gradually deforms into an irregular shape along the tilt direction, the front contact angle decreases to 131°, and the rear contact angle increases to 146°; as the tilt angle gradually increases, the front contact angle continues to decrease until the tilt angle increases to 27°, the front contact angle gradually decreases to 118°, and the rear contact angle increases to 157°, at which time the liquid rolls down the sample surface along the groove direction, and no liquid remains on its surface. This phenomenon may be because as the sample tilt angle increases, the gravity of the liquid gradually increases and causes an imbalance in the distribution of the liquid surface tension, and the liquid gradually overcomes the surface adhesion and rolls down along the linear embedding direction. At the same time, from Figure 5b and 5c2 found that when the liquid rolled down in the horizontal direction, as the tilt angle increased to 46°, the front contact angle decreased from 141° to 86°, while the rear contact angle increased from 140° to 169°, and the contact hysteresis angle decreased from 1° to -83°. Compared with the longitudinal contact hysteresis angle decreasing from -1° to -39°, the contact hysteresis of the liquid was stronger when it rolled down in the longitudinal direction, and the liquid easily rolled down in the longitudinal direction along the sample surface. This may be because the linear embedded structure formed an air cushion structure between the liquid and the sample surface. When the liquid rolled down in the horizontal direction, the air cushion structure gradually decreased, the contact area between the liquid and the sample surface increased, and the droplet surface adhesion increased, making it difficult to roll down.

[0105] Furthermore, the rolling characteristics of different liquid volumes and different types of liquids on the surface of PLA microfiber composites were investigated. Figure 5 As shown in d-5h. Figure 5 d shows the tilt angles of 10μL, 20μL, 30μL, 40μL and 50μL distilled water when rolling down the sample surface at a hot air pressure of 41kPa. When 10μL of liquid rolled down on the sample surface, the vertical and horizontal rolling angles were 46° and 88°, respectively. When the liquid volume continued to increase, the vertical and horizontal rolling angles showed a decreasing trend until the liquid volume increased to 50μL, and the vertical and horizontal rolling angles decreased to 12° and 37°, respectively. This shows that the increase in liquid volume has a positive effect on the rolling behavior of the liquid on the sample surface.

[0106] Figure 5 e-5f is the variation curve of the rolling angle of samples with different hot air pressures. It can be seen from the figure that the rolling angles of different types of liquids are negatively correlated with the hot air pressure, that is, as the hot air pressure increases to 41kPa, the longitudinal rolling angles of 50μL distilled water, synthetic blood and coffee decrease from 45°, 62° and 48° to 14°, 23° and 17°, respectively, and the transverse rolling angles decrease from 63°, 75° and 65° to 37°, 46° and 43°, respectively. The longitudinal rolling angles decrease by 68.9%, 62.9% and 64.6%, respectively, and the transverse rolling angles decrease by 41.27%, 38.67% and 33.85%, respectively. In addition, the liquid rolling angle of the PLA microfiber composite sample also shows a gradual decreasing trend with the increase of the water needle energy, such as Figure 5 As shown in g-5h, when the water injection energy is 1410.9 kJ / m 2 When the vertical rolling angles of 50 μL distilled water, synthetic blood and coffee were 41°, 58° and 46°, and the horizontal rolling angles were 65°, 78° and 67°, the water injection energy increased to 4703.2 kJ / m 2, the longitudinal rolling angles decreased to 13°, 19° and 16°, respectively, and the transverse rolling angles decreased to 38°, 45° and 42°, respectively. This result may be because the changes in fiber diameter and water needle energy increase the entanglement between the two layers of fibers, increase the linear embedded structure of the PLA ultrafine fiber composite material, and provide more transmission channels for the liquid to roll off.

[0107] The spray test is also a key indicator for measuring the ability of liquid to roll off the surface of ultra-fine fiber materials. Figure 5 i shows a schematic diagram of spraying 100 mL of distilled water dyed with 1% reactive brilliant blue on the sample surface with a hot air pressure of 41 kPa. Figure 5 It can be clearly seen in Figure 1 that when the sample is fixed on a 45° tilting table, the dyed liquid does not wet the sample surface and is very easy to roll down along the sample surface. At the same time, by observing the surface of the sample after spraying, it is found that only a small amount of liquid remains in the PLA ultrafine fiber layer and no large-area wetting of the liquid is found on both sides of the sample. The water wetting levels of different samples are shown in Table 2. It can be seen that with the increase of hot air pressure, the water wetting level of the sample gradually decreases from level 4-5 to level 2, the surface wetting area gradually decreases, and the residual liquid volume also gradually decreases. At the same time, the water wetting level of the sample also decreases accordingly with the increase of the water needle energy, that is, the water needle energy increases to 4703.2kJ / m 2 , the water wetting level decreased from level 4 to level 2, indicating that the PLA microfiber composite material sample is suitable for application scenarios that require protection from liquid wetting.

[0108] Table 6. Water repellency rating of PLA microfiber composite samples

[0109]

[0110] (4) Hydrostatic pressure test

[0111] The samples were tested for hydrostatic pressure resistance using a YG826G fully automatic hydrostatic pressure tester (Ningbo Textile Co., Ltd.) with a timed pressurization method. The pressurization rate was 10,000 Pa / min, and 5 samples were selected for each group to be tested and the average value was taken.

[0112] Figure 4 i-4j shows the hydrostatic pressure resistance test of PLA microfiber composite samples. When the hot air pressure is 33kPa, 35kPa, 39kPa and 41kPa, the hydrostatic pressure resistance values ​​are 2379Pa, 2799Pa, 3897Pa and 4415Pa respectively. When the water needle energy is 1410.9kJ / m 2 、1699.3kJ / m 2 、2105.9kJ / m 2 、2821.9kJ / m 2 and 4703.2 kJ / m 2, and the hydrostatic pressure resistance values ​​are 2398Pa, 2716Pa, 3156Pa, 3885Pa and 4379Pa respectively. This shows that with the enhancement of the linear embedded structure, the PLA microfiber material exhibits efficient liquid shielding ability, which is crucial for the application of PLA microfiber protective materials in environments requiring liquid shielding.

[0113] (5) Mechanical properties test

[0114] Tensile fracture properties: The longitudinal and transverse tensile properties of the samples were tested using a nonwoven material constant temperature mechanical properties analyzer (HD026S-100, Nantong Hongda Experimental Instrument Co., Ltd.). Test conditions: The longitudinal and transverse dimensions of the samples were 5×20 cm and 5×10 cm, respectively, the tensile rate was 100 mm / min, and the longitudinal and transverse test gauges were 100 mm and 50 mm, respectively.

[0115] Bursting performance: A fabric strength tester (YG026MD-250, Dayong Textile Instrument Co., Ltd.) was used to test the bursting strength of samples with a surface density of 100g.

[0116] Excellent mechanical properties are crucial for the use of ultra-fine fiber materials in the field of protection. Figure 6 a-6c shows the force-displacement curve and bursting strength curve of the PLA ultrafine fiber composite sample during tensile fracture. 2 Increased to 4703.2 kJ / m 2 , the longitudinal and transverse breaking strength increased from 325.9N and 298.3N to 391.5N and 360.7N, respectively. At the same time, the longitudinal and transverse breaking elongations increased from 20.9% and 16.2% to 23.2% and 18.4%, respectively, and the bursting strength increased from 259.7N to 379.4N. This is because the cotton woven fabric itself has excellent mechanical properties due to its regular fiber web arrangement. With the increase of the impact of the high-pressure water jet, the linear entanglement structure of the PLA microfiber and the cotton fiber becomes tighter, the friction between the fibers increases, and the mechanical properties of the PLA microfiber composite sample are enhanced. These results show that the linear embedding structure between the fibers directly affects the mechanical properties of the sample, especially in applications that resist external forces. Figure 6 e and 6f show that the water needle energy is 2105.9 kJ / m 2The influence of the embedded structure of PLA ultrafine fiber composite samples under different tensile conditions. When the sample is stretched along the MD direction, the directional PLA fibers rely on their own bonding force to resist the external load. As the external load increases, the embedded part of the PLA fiber and the cotton fiber becomes the main force to resist the external force. When the embedded structure between the two layers of fibers cannot resist the load, the entire fiber mesh structure is destroyed. Along the CD direction, the linearly arranged fibers are rearranged along the direction of the external force. As the load increases, the two layers of fibers are stretched to the maximum length and then broken. The external force borne by the broken fiber is further transmitted to the adjacent fibers, eventually leading to the destruction of the entire fiber mesh.

[0117] Comparison 80g / m 2 PLA ultrafine fiber composite material sample, 60g / m 2 PLA / PW@SiO 2 Microfiber material and 65g / m 2 The mechanical properties of PP meltblown fiber materials were found to be Figure 6 d), the longitudinal breaking strength of PLA ultrafine fiber composite material sample reached 430.4N, which is much higher than 52.9N of PLA ultrafine fiber material and 42.6N of melt-blown nonwoven material, about 8.2 times and 10.1 times in the longitudinal direction. This result shows that PLA ultrafine fiber composite material meets the high strength performance requirements in the fields of outdoor protection, personal protection and medical protection, and has broad application potential in the field of ultrafine fiber protective materials.

[0118] (6) Transparency test

[0119] Water vapor transmission rate: The water vapor transmission rate of the sample was tested using a W3 cup method water vapor transmission rate tester (Jinan Languang Electromechanical Technology Co., Ltd.) Test conditions: The test temperature was 38°C and the test humidity was 75%.

[0120] Air permeability: The test area is 100cm using the YG416E-Ⅲ fully automatic air permeability meter (Ningbo Textile Instrument Factory). 2 Air permeability of the sample. Test conditions: The pressure difference between the upper and lower surfaces of the material is 100Pa.

[0121] Excellent permeability and soft and comfortable properties are also key factors in the widespread application of PLA microfiber protective materials. Figure 7a-7b shows the regular curves of the air permeability and water vapor permeability of the ultrafine fiber composite material sample with the change of hot air pressure and water spunlace energy. It can be seen from the figure that the air permeability and water vapor permeability of the sample show a gradually decreasing trend with the increase of hot air pressure and water spunlace energy, that is, when the hot air pressure is 33kPa, 35kPa, 39kPa and 41kPa respectively, the air permeability is 134.0mm / s, 113.2mm / s, 88.5mm / s and 78.9mm / s respectively, and the water vapor permeability is 6288.9g / (m 2 ·24h)、5794.1g / (m 2 ·24h)、5284.8g / (m 2 ·24h) and 4802.6g / (m 2 ·24h). When the water injection energy is from 1410.9kJ / m 2 Increased to 4703.2 kJ / m 2 The air permeability and water vapor of PLA ultrafine fiber composite samples increased from 125.8 mm / s to 5862.4 g / (m 2 ·24h) is reduced to 75.5mm / s and 4802.6g / (m 2 ·24h). This is because when the hot air pressure and water needle energy increase, the two layers of fiber embedding increase, the fibers are arranged more closely, resulting in a reduction in the transmission channels of air and water vapor. However, this result still meets the requirements of "GB 19082-2009 Technical Requirements for Disposable Medical Protective Clothing" and "FZ / T73026-2013 Knitted Sportswear" that the water vapor permeability of medical protective clothing and outdoor protective clothing should not be less than 2500g / m 2 24h and 5000g / m 2 ·24h requirement. Figure 7 c-7d shows the water vapor permeability of PLA microfiber composite samples. 100cm 2 The circular sample was covered on a beaker filled with 100℃ distilled water and heated at a constant temperature of 100℃ using a heating table. As the heating time increased to 200min, the water level in the beaker decreased from 6.79cm to 5.41cm, indicating that the sample had good air permeability. Figure 7 e-7f shows the softness scores of samples with different hot air pressures and water injection energies. It can be seen that with the continuous increase of hot air pressure, the softness score of the PLA microfiber composite material sample gradually increases. When the hot air pressure increases to 41kPa, the softness score reaches the maximum, which is 79.7 points. Correspondingly, the water injection energy increases from 1410.9kJ / m 2 Increased to 4703.2 kJ / m 2The sample softness score increased from 68.4 points to 78.1 points. The excellent softness also gives PLA microfiber composites broad application prospects in personal protection fields such as packaging materials, protective clothing and protective masks.

[0122] Application Examples

[0123] Figure 8 The rolling ability of PLA microfiber composite samples in different practical applications is demonstrated. Figure 8 a shows that 30 μL of distilled water has a water injection energy of 4703.2 kJ / m 2 The rolling solid image of the sample surface shows that the liquid rolls off the sample surface in only 1.5 seconds and no liquid residue is found, indicating that the sample has excellent liquid rolling ability. Figure 8 b-8c simulates the self-cleaning effect of samples on pollutants such as sludge and blood. Figure 8 b is a schematic diagram of the process of self-cleaning sludge of the sample with hot air pressure of 39kPa. When the sludge contaminates the surface of the sample, the liquid water carrying the pollutants can quickly roll off the surface of the sample, effectively removing the sludge, and the surface of the sample remains clean. At the same time, after the blood contaminates the surface of the sample, it can also be rinsed and removed with distilled water. Observing the surface of the sample after cleaning with distilled water, it can be found that the blood has not penetrated the surface and there is no residue. Figure 8 d shows the simulated application of PLA ultrafine fiber composite materials in medical packaging materials. The excellent flexibility of the sample enables it to be folded into any shape and fit tightly with objects. In addition, no residue remains when the dyed distilled water rolls off the surface of the sample, indicating that it has great application potential in the field of medical protective materials. Figure 8 e shows the water splashing experiment of PLA microfiber composite samples and traditional cotton protective lab coats. When a large amount of water was splashed on the samples and cotton lab coats, compared with the cotton protective lab coats that were wetted over a large area, the liquid water did not penetrate the surface of the PLA microfiber composite sample, only a small amount of liquid remained, and most of the liquid water rolled down along the surface of the sample. These results show that the PLA microfiber composite sample has the ability to easily roll off liquid, which provides significant advantages for its application as a protective material in complex environments.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an anti-agglomeration and easy-to-roll polylactic acid ultrafine fiber composite material, characterized in that: Here are the steps: (1) Adding silicon dioxide into the paraffin melt for melting and blending, and obtaining the PW@SiO2 blend after cooling; (2) mixing the PW@SiO2 blend obtained in step (1) with dried polylactic acid, and preparing a highly oriented PLA ultrafine fiber web by melt-blowing, web-forming and secondary drawing; (3) The highly oriented PLA ultrafine fiber web obtained in step (2) is stacked with the cotton woven fabric in the thickness direction, and a linear embedded polylactic acid ultrafine fiber composite material is obtained by a hydroentanglement reinforcement process.

2. The method for preparing the anti-agglomeration and easy-to-roll-off polylactic acid ultrafine fiber composite material according to claim 1, characterized in that: The particle size of the silicon dioxide in step (1) is 1-3 μm and the density is 2.2 g / cm 3 .

3. The method for preparing the anti-agglomeration and easy-to-roll-off polylactic acid ultrafine fiber composite material according to claim 2, characterized in that: In the step (2), the mass ratio of polylactic acid, paraffin wax and silicon dioxide is (94-96.4):3:(0.6-3).

4. The method for preparing the anti-agglomeration and easy-to-roll-off polylactic acid ultrafine fiber composite material according to claim 3, characterized in that: The process parameters of melt blowing in step (2) are as follows: the temperature of zone 1 of the screw extruder is 170-190°C, the temperature of zone 2 is 200-220°C, the temperature of zone 3 is 220-240°C, the die head temperature is 220-240°C, the hot air temperature is 240-260°C, the hot air pressure is 33-41 kPa, and the receiving distance of the receiving mesh curtain in the melt blowing experimental equipment is 15-20 cm.

5. The method for preparing the anti-agglomeration and easy-to-roll-off polylactic acid ultrafine fiber composite material according to claim 4, characterized in that: The drafting ratio of the secondary drafting in the step (2) is 1.5-3.

0.

6. The method for preparing the anti-agglomeration and easy-to-roll-off polylactic acid ultrafine fiber composite material according to claim 5, characterized in that: During the water stab reinforcement process in step (3), the water stab energy is 1410.9-4703.2 kJ / m 2 ; The surface density of cotton woven fabric is 60 g / m 2 .

7. A polylactic acid ultrafine fiber composite material that prevents accumulation and rolls off, prepared by the preparation method described in any one of claims 1 to 6.

8. The anti-agglomeration and easy-to-roll-off polylactic acid ultrafine fiber composite material according to claim 7, characterized in that: The linear embedded polylactic acid ultrafine fiber composite material has a modal pore size of 19-48 μm, a porosity of 47-79%, and a water contact angle of 139-164°.

9. The anti-accumulation and easy-to-roll-off polylactic acid ultrafine fiber composite material according to claim 8, characterized in that: The linear embedded polylactic acid ultrafine fiber protective material has a breaking strength of 298.3-391.5 N and a bursting strength of 259.7-379.4 N.

10. Application of the anti-agglomeration and anti-rolling polylactic acid ultrafine fiber composite material according to claim 7 in the field of packaging materials or medical protection.

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