High-strength high-haze transparent functional polylactic acid monofilament and preparation method thereof

Abstract

The invention discloses a high-strength high-haze transparent functional polylactic acid monofilament and a preparation method thereof, and belongs to the field of high polymer material processing. The preparation method comprises the following steps: melting, blending and granulating a high-molecular-weight polymer and inorganic nanoparticles to obtain functional master batch slices; carrying out melt blending granulation on the functional master batch slices and polylactic acid to obtain polylactic acid functional slices; and finally, carrying out melt spinning by taking the polylactic acid functional slice as a raw material to obtain the high-strength high-haze transparent functional polylactic acid monofilament. By introducing a high molecular weight polymer dispersion carrier and constructing a double-dispersion structure, inorganic nanoparticles do not need to be modified, efficient and uniform dispersion of the inorganic nanoparticles in PLA is realized, meanwhile, a spinning processing external field is regulated and controlled, so that the size of a dispersion phase is smaller than the wavelength of visible light, and unification of high strength, high light transmittance and high haze of the PLA monofilament is realized.

Description

Technical Field

[0001] The invention relates to a high-strength, high-fog, transparent functional polylactic acid monofilament and a preparation method thereof, and belongs to the field of polymer material processing. Background Art

[0002] Polylactic acid (PLA) is a renewable, biodegradable thermoplastic polymer that can replace petroleum-based polymers as fiber raw materials, addressing resource shortages, environmental pollution, and carbon emissions associated with the development of synthetic fibers. Currently, PLA fiber has been industrialized and is widely used in clothing, hygiene products, packaging, and other fields. High-strength, high-diameter monofilaments are a specialized fiber type, primarily used in industrial applications. However, high-strength, high-haze, transparent PLA monofilaments and their functionalized products are relatively rare, and there are no high-strength, high-haze, transparent functional PLA monofilaments. These products can be used in areas such as automotive interiors. Their high transparency enhances the connection between interior and exterior, while their high haze reduces glare and dizziness caused by strong external light. Furthermore, high haze and transparency further enhance the functionality of the PLA monofilaments. For example, high transparency increases light penetration into the monofilament, fully utilizing the photothermal nanoparticles within the monofilament. High haze also promotes forward scattering of light, further enhancing the nanoparticles' effectiveness and improving photothermal efficiency. With the rapid development of new energy vehicles, these products hold promising market prospects. However, the development of this product faces the following difficulties: (1) Polylactic acid is a semi-crystalline polymer. High strength requires high crystallinity, but high crystallinity makes it difficult to achieve high transparency; (2) Nanoparticles have a large specific surface area and are prone to agglomeration. They are particularly difficult to disperse in high molecular weight spinning-grade thermoplastic polymers. The agglomeration of inorganic nanoparticles will lead to a decrease in the spinnability and mechanical properties of polylactic acid, and make it difficult to achieve transparency.

[0003] At present, a lot of research has been conducted both domestically and internationally on the dispersion of inorganic nanoparticles in fiber-grade thermoplastic polymers. Three methods, namely surface chemical modification, in-situ polymerization and low molecular weight polymer dispersant, have been industrially used for the dispersion of nanoparticles in melt spinning. The surface chemical modification method is to graft small molecules or oligomers onto the surface of inorganic nanoparticles to inhibit agglomeration, increase the interaction between nanoparticles and polymers, and achieve the dispersion of nanoparticles in polymers. However, this method requires organic solvents and purification, and the process is long. In addition, if the purification is not sufficient, modifiers will remain in the nanoparticles, resulting in a decrease in the mechanical properties of the fiber. The in-situ polymerization method is a method of introducing nanoparticles during the synthesis of polymers to achieve nanoparticle dispersion. This method is an effective method for achieving nanoparticle dispersion in the spinning industry, but its use scenarios are limited and it is not suitable for systems of slices and nanoparticle hybrids. The low-molecular-weight polymer dispersant method introduces a low-molecular-weight polymer dispersant into the polymer matrix / nanoparticle blend system to achieve uniform dispersion of the nanoparticles. In this method, the dispersant has a low melting point and viscosity, melts before the resin matrix during the melt blending and granulation process, and has good fluidity, allowing it to flow into the gaps between powders or agglomerates, wetting and coating the surface of the powder particles, breaking up the agglomeration between the powder particles. If the dispersant and the resin matrix have similar polarity, the two will have good compatibility, and the dispersant will carry the encapsulated powder particles and evenly disperse them in the matrix, preventing further agglomeration. This method is currently the most commonly used in the chemical fiber industry, but the introduction of low-molecular-weight dispersants can reduce the spinnability and mechanical properties of the material. Summary of the Invention

[0004] [Technical Issues]

[0005] Polylactic acid is a semi-crystalline polymer. High strength requires high crystallinity, but high crystallinity makes it difficult to achieve high transparency.

[0006] Nanoparticles have a large specific surface area and are prone to agglomeration, making them particularly difficult to disperse in high molecular weight spinning-grade thermoplastic polymers. The agglomeration of inorganic nanoparticles can lead to reduced spinnability and mechanical properties of polylactic acid, as well as difficulty in achieving transparency.

[0007] Existing industrial methods for dispersing nanoparticles in polymers all have certain defects; surface chemical modification methods require the use of organic solvents and need to be purified; in situ polymerization methods are not universally applicable; and low molecular weight polymer dispersant methods can cause a decrease in the material's spinnability and mechanical properties.

[0008] [Technical solution]

[0009] To address the above-mentioned issues, the present invention provides a high-strength, high-haze, transparent functional polylactic acid monofilament and a method for preparing the same. Specifically, a high molecular weight polymer is used as a dispersion carrier, melt-blended and granulated with inorganic nanoparticles to produce a functional masterbatch. The functional masterbatch is then melt-blended and granulated with polylactic acid to create a bidisperse structure, yielding polylactic acid functional chips. Finally, the polylactic acid functional chips are melt-spun to produce polylactic acid monofilament. The polylactic acid monofilament produced by this invention exhibits high strength, high haze, and high transparency.

[0010] A first object of the present invention is to provide a method for preparing high-strength, high-fog, transparent functional polylactic acid monofilament, comprising the following steps:

[0011] (1) Primary granulation:

[0012] The high molecular weight polymer and inorganic nanoparticles are melt-blended and granulated to obtain functional masterbatch chips;

[0013] Wherein, the high molecular weight polymer dispersion carrier is one of polypropylene, polyethylene, polyvinylidene fluoride, polytrimethylene terephthalate, polybutylene terephthalate, poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), polybutylene terephthalate-adipate, polybutylene succinate, nylon 12, nylon 11, polycaprolactam, nylon 1010, nylon 1212, and nylon 612;

[0014] (2) Secondary granulation:

[0015] The functional masterbatch slices are melt-blended and granulated with polylactic acid to obtain polylactic acid functional slices;

[0016] (3) Preparation of monofilament:

[0017] The polylactic acid functional chips are used as raw materials for melt spinning to obtain high-strength, high-fog and transparent functional polylactic acid monofilaments.

[0018] In one embodiment of the present invention, the mass ratio of polylactic acid, high molecular weight polymer, and inorganic nanoparticles is 80-95:5-20:0.1-5.

[0019] In one embodiment of the present invention, the particle size of the inorganic nanoparticles in step (1) is 1 to 300 nm, and the aggregate size of the inorganic nanoparticles is less than 700 nm. When the aggregate size of the inorganic nanoparticles is greater than 700 nm, the transparency requirement cannot be met.

[0020] In one embodiment of the present invention, the steps (1) and (2) are premixed for 3 to 15 minutes before granulation, the granulation temperature is 130 to 280° C., the rotation speed is 50 to 500 rpm, the vacuum drying temperature is 65 to 120° C., and the time is 8 to 48 hours.

[0021] In one embodiment of the present invention, the weight average molecular weight of the polylactic acid in step (2) is 1.0×10 5 ~6.0×10 6 ; The content of D-LA structural units in polylactic acid is 0% to 10 mol%.

[0022] In one embodiment of the present invention, in step (2), the inorganic nanoparticles are dispersed in a high molecular weight polymer dispersion carrier, and the dispersion carrier is dispersed in a polylactic acid matrix to construct a double dispersion structure, thereby achieving efficient and uniform dispersion of the inorganic nanoparticles in the polymer matrix.

[0023] In one embodiment of the present invention, the melt spinning in step (3) is melt horizontal spinning, comprising melt extrusion - water bath cooling - hot steam stretching - hot air stretching - heat setting;

[0024] Among them, the spinning temperature is 150-255°C, the first roller winding speed is 1-50m / min, the water bath temperature is 10-75°C; the hot steam drawing temperature is 75-95°C, and the drawing ratio is 2-6.5; the second hot air drawing temperature is 100-125°C, and the drawing ratio is 1.0-1.5; the heat setting temperature is 100-135°C.

[0025] The second object of the present invention is to provide high-strength, high-fog, transparent functional polylactic acid monofilament prepared by the method of the present invention.

[0026] In one embodiment of the present invention, the high-strength and high-haze transparent functional polylactic acid monofilament has a strength of ≥2.5 cN / dtex, a light transmittance of ≥80%, and a haze of ≥70%.

[0027] In one embodiment of the present invention, the high molecular weight polymer dispersion carrier in the high-strength, high-fog, transparent functional polylactic acid monofilament exists in the form of microfibers in the monofilament, and the diameter thereof does not exceed 700 nm.

[0028] The third object of the present invention is to provide a high-strength, high-haze, transparent functional polylactic acid yarn, which is prepared from the high-strength, high-haze, transparent functional polylactic acid monofilament described in the present invention.

[0029] The fourth object of the present invention is to provide a high-strength, high-fog, transparent functional polylactic acid fabric, which is prepared from the high-strength, high-fog, transparent functional polylactic acid monofilament described in the present invention.

[0030] A fifth object of the present invention is to provide an automobile interior, which uses the high-strength, high-fog, transparent functional polylactic acid monofilament described in the present invention.

[0031] The sixth object of the present invention is to use the high-strength, high-haze, transparent functional polylactic acid monofilament, high-strength, high-haze, transparent functional polylactic acid yarn, and high-strength, high-haze, transparent functional polylactic acid fabric described in the present invention in the field of functional materials.

[0032] In one embodiment of the present invention, the field of functional materials includes clothing, hygiene, packaging and other fields.

[0033] In one embodiment of the present invention, the functional material includes automotive interior trim and the like.

[0034] A seventh object of the present invention is to provide a method for improving the strength, haze, and transparency of polylactic acid monofilaments, comprising the following steps:

[0035] (1) Primary granulation:

[0036] The high molecular weight polymer and inorganic nanoparticles are melt-blended and granulated to obtain functional masterbatch chips;

[0037] Wherein, the high molecular weight polymer dispersion carrier is one of polypropylene, polyethylene, polyvinylidene fluoride, polytrimethylene terephthalate, polybutylene terephthalate, poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), polybutylene terephthalate-adipate, polybutylene succinate, nylon 12, nylon 11, polycaprolactam, nylon 1010, nylon 1212, and nylon 612;

[0038] (2) Secondary granulation:

[0039] The functional masterbatch slices are melt-blended and granulated with polylactic acid to obtain polylactic acid functional slices;

[0040] (3) Preparation of monofilament:

[0041] The polylactic acid functional chips are used as raw materials for melt spinning to obtain high-strength, high-fog and transparent functional polylactic acid monofilaments.

[0042] [Beneficial Effects]

[0043] (1) The high-strength, high-fog, transparent functional polylactic acid monofilament prepared by the present invention is mainly composed of renewable and biodegradable thermoplastic polylactic acid, and is produced by melt spinning, which has the characteristics of being green, environmentally friendly and low-carbon.

[0044] (2) The present invention proposes a new method for constructing a double-dispersed structure to achieve efficient dispersion of inorganic nanoparticles in polylactic acid. Using a high molecular weight polymer as a dispersion carrier, the inorganic nanoparticles are dispersed in the dispersion carrier, and the high molecular weight polymer dispersion carrier is dispersed in the polylactic acid matrix polymer. This double-dispersed structure is constructed so that the size of the dispersed phase of the high molecular weight polymer dispersion carrier is significantly smaller than the diameter of the spinneret, ensuring smooth spinning. Furthermore, since the dispersion carrier is a high molecular weight polymer, the mechanical properties of the final monofilament will not be reduced.

[0045] (3) The present invention achieves the unity of high strength, high haze and high transparency of the monofilament by constructing a double-dispersed structure and regulating the external field of the spinning process.

[0046] (4) The present invention uses a special forming process for high-strength and large-diameter monofilaments. After melt extrusion, the polylactic acid functional slices are rapidly cooled in a water bath to inhibit the rapid crystallization of the polylactic acid, so that the polylactic acid monofilaments are in an amorphous state for subsequent high-magnification drawing. Then, at a temperature slightly higher than the glass transition temperature of the polylactic acid, they are subjected to high-magnification drawing by hot steam to improve the orientation of the polylactic acid and form small crystal nuclei to avoid the formation of large-sized crystals. After hot air drawing, the orientation and crystallinity of the polylactic acid monofilaments are further improved. Finally, heat setting is performed to increase the thickness, crystallinity and dimensional stability of the lamellae to produce high-strength and transparent polylactic acid monofilaments. At the same time, the polylactic acid monofilaments contain a dispersed phase formed by a high-molecular-weight polymer dispersion carrier and inorganic nanoparticles. During the high-magnification drawing process, the high-molecular-weight polymer dispersion carrier is microfibrillated. Furthermore, due to the interaction between the inorganic nanoparticles and the polymer dispersion carrier, the inorganic nanoparticles are further dispersed during the microfibrillation of the high molecular weight polymer dispersion carrier, resulting in the size of the high molecular weight polymer dispersion carrier microfibers, inorganic nanoparticles, and their aggregates not exceeding the wavelength of visible light, resulting in high transparency of the functionalized polylactic acid monofilament. Furthermore, due to the forward scattering effect of the high molecular weight polymer dispersion carrier and the inorganic nanoparticles, the functionalized polylactic acid monofilament has a high haze.

[0047] (5) The high-strength, high-fog, transparent functional polylactic acid monofilament prepared by the present invention not only has high strength, high haze and high transparency, but also can further increase the function of the monofilament due to its high haze and high transparency. DETAILED DESCRIPTION

[0048] The following describes preferred embodiments of the present invention. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0049] Test method:

[0050] 1. Diameter test method:

[0051] The diameter of the monofilaments was measured using a scanning electron microscope.

[0052] 2. Tensile mechanical properties test method:

[0053] The tensile mechanical properties of the fiber were tested in accordance with the national standard "GB / T 14344-2022 Test method for tensile properties of chemical fiber filaments".

[0054] 3. Transmittance and haze test methods:

[0055] The monofilaments were arranged closely in parallel to form a single monofilament layer of 5 cm × 5 cm. The transmittance and haze of light of a specific wavelength were measured in accordance with the national standard "GB / T 2410-2008 Transparent Plastics Light Transmittance and Haze".

[0056] Example 1

[0057] A method for preparing high-strength, high-fog, transparent functional polylactic acid monofilament comprises the following steps:

[0058] (1) Primary granulation:

[0059] Nylon 11 (PA11) and titanium dioxide (TiO2) nanoparticles with a particle size of 30 nm were placed in a high-speed mixer and premixed for 5 minutes. The mixture was then melt-blended and granulated in a twin-screw blender at a granulation temperature of 200°C and a screw speed of 450 rpm to obtain PA11 / TiO2 functional masterbatch chips. The obtained functional masterbatch chips were vacuum-dried at 100°C for 24 hours and set aside.

[0060] (2) Secondary granulation:

[0061] The weight average molecular weight is 2.2×10 5 , polylactic acid (PLA) with a D-LA content of 0.25 mol% and PA11 / TiO2 functional masterbatch chips were placed in a high-speed mixer for premixing for 5 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 200° C. and a screw speed of 450 rpm to obtain PLA / PA11 / TiO2 polylactic acid functional chips; the obtained polylactic acid functional chips were vacuum-dried at 100° C. for 24 hours and set aside;

[0062] (3) Preparation of monofilament:

[0063] PLA / PA11 / TiO2 polylactic acid functional chips are used as raw materials, and PLA / PA11 / TiO2 polylactic acid monofilaments are produced through melt horizontal spinning, melt extrusion, water bath cooling, hot steam stretching, hot air stretching, and heat setting.

[0064] Among them, the mass ratio of PLA, PA11, and TiO2 is 90:10:1;

[0065] The spinning temperature is 245°C, the first roller winding speed is 20m / min, and the water bath temperature is 70°C; the hot steam drawing temperature is 90°C, and the drawing ratio is 5.4; the second hot air drawing temperature is 120°C, the drawing ratio is 1.2, and the heat setting temperature is 120°C.

[0066] Comparative Example 1

[0067] Omit step (1) of Example 1;

[0068] TiO2 and PLA are directly melt-blended and granulated to obtain PLA / TiO2 chips. PLA / TiO2 chips are used as raw materials and melt-spinned horizontally, followed by melt extrusion, water bath cooling, hot steam stretching, hot air stretching, and heat setting to obtain PLA / TiO2 monofilaments.

[0069] Among them, the mass ratio of PLA and TiO2 is 100:1;

[0070] The spinning process parameters remained the same as in Example 1.

[0071] Comparative Example 2

[0072] The temperature of the second hot air drawing in step (3) of Example 1 was changed to 130° C., and the other conditions remained the same as in Example 1 to prepare a monofilament.

[0073] Comparative Example 3

[0074] The second hot air drawing ratio in step (3) of Example 1 was changed to 1.6 times, and the other conditions were kept the same as in Example 1 to prepare a monofilament.

[0075] Comparative Example 4

[0076] The PLA in step (2) of Example 1 was changed to a PLA with a weight average molecular weight of 5.3×10 4 , PLA with a D-LA content of 0.25 mol%, and other procedures were consistent with those in Example 1 to prepare monofilaments.

[0077] Comparative Example 5

[0078] The PA11 in step (1) of Example 1 was adjusted to polyvinyl acetate (PVAc), and the other parts were kept consistent with Example 1 to prepare a monofilament.

[0079] Comparative Example 6

[0080] The mass ratio of PLA, PA11 and TiO2 in Example 1 was adjusted to 97:3:1; other parameters were kept consistent with Example 1 to prepare a monofilament.

[0081] The monofilaments obtained in Example 1 and Comparative Examples 1 to 6 were subjected to performance tests and the test results are as follows:

[0082] Table 1 Test results

[0083]

[0084] As can be seen from Table 1: without introducing PA11 as a polymer carrier, PLA and TiO2 were directly melt-blended to prepare PLA / TiO2 chips, and PLA / TiO2 chips were used as raw materials to spin monofilaments. The spinning continuity was poor, the strength of the monofilaments was low, and the transmittance and haze were low. This was because TiO2 was not well dispersed in PLA; when the temperature of the second hot air drawing was too high, 130°C, although the PLA / PA11 / TiO2 monofilaments had good spinnability and good mechanical properties, their transparency and haze were low; when the second hot air drawing ratio was too high, 1.6 times, although the PLA / PA11 / TiO2 monofilaments had good spinnability and good mechanical properties, their transparency and haze were low; The filament has good spinnability and good mechanical properties, but its transparency and haze are low; when PLA with a lower molecular weight is selected, the spinnability of PLA / PA11 / TiO2 blend chips is poor, and large-diameter PLA / PA11 / TiO2 monofilaments cannot be produced; when PA11, which is incompatible with PLA, is replaced with PVAc, which is compatible with PLA, the dispersibility of TiO2 in PLA / PVAc / TiO2 decreases, the strength of the monofilament decreases, the spinnability decreases, and the transparency and haze also decrease; when the PA11 content is reduced, it is difficult for PA11 to encapsulate TiO2, the dispersibility of TiO2 decreases, the spinnability of the monofilament decreases, and the transparency and haze also decrease.

[0085] Example 2

[0086] A method for preparing high-strength, high-fog, transparent functional polylactic acid monofilament comprises the following steps:

[0087] (1) Primary granulation:

[0088] Polypropylene (PP) and zinc oxide (ZnO) nanoparticles with a particle size of 20 nm were pre-mixed in a high-speed mixer for 5 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 195°C and a screw speed of 400 rpm to obtain PP / ZnO functional masterbatch chips;

[0089] (2) Secondary granulation:

[0090] The weight average molecular weight is 2.0×10 5 PLA with a D-LA content of 4.0 mol% and PP / ZnO functional masterbatch chips were placed in a high-speed mixer for premixing for 5 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 200° C. and a screw speed of 400 rpm to obtain PLA / PP / ZnO polylactic acid functional chips; the obtained polylactic acid functional chips were vacuum-dried at 100° C. for 24 hours and set aside;

[0091] (3) Preparation of monofilament:

[0092] PLA / PP / ZnO polylactic acid functional chips are used as raw materials, and PLA / PP / ZnO polylactic acid monofilaments are produced through melt horizontal spinning, melt extrusion, water bath cooling, hot steam stretching, hot air stretching, and heat setting.

[0093] Among them, the mass ratio of PLA, PP, and ZnO is 95:5:0.5;

[0094] The spinning temperature is 245°C, the first roller winding speed is 20m / min, and the water bath temperature is 70°C; the hot steam drawing temperature is 90°C, and the drawing ratio is 6.0; the second hot air drawing temperature is 120°C, the drawing ratio is 1.2, and the heat setting temperature is 120°C.

[0095] Example 3

[0096] A method for preparing high-strength, high-fog, transparent functional polylactic acid monofilament comprises the following steps:

[0097] (1) Primary granulation:

[0098] Poly(trimethylene terephthalate) (PTT) and copper oxide (CuO) were pre-mixed in a high-speed mixer for 8 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 240° C. and a screw speed of 420 rpm to obtain PTT / CuO functional masterbatch chips. The obtained functional masterbatch chips were vacuum-dried at 110° C. for 24 hours and set aside.

[0099] (2) Secondary granulation:

[0100] The weight average molecular weight is 2.0×10 5 PLA with a D-LA content of 4.0 mol% and PTT / CuO functional masterbatch chips were placed in a high-speed mixer for premixing for 5 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 235° C. and a screw speed of 420 rpm to obtain PLA / PTT / CuO polylactic acid functional chips; the obtained polylactic acid functional chips were vacuum-dried at 100° C. for 24 hours and set aside;

[0101] (3) Preparation of high-strength, high-fog, transparent functional polylactic acid monofilaments:

[0102] PLA / PTT / CuO polylactic acid functional chips are used as raw materials, and PLA / PTT / CuO polylactic acid monofilaments are produced through melt horizontal spinning, melt extrusion, water bath cooling, hot steam stretching, hot air stretching, and heat setting.

[0103] Among them, the mass ratio of PLA, PTT, and CuO is 90:10:0.8;

[0104] The spinning temperature is 245°C, the first roller winding speed is 20m / min, and the water bath temperature is 70°C; the hot steam drawing temperature is 90°C, and the drawing ratio is 5.4; the second hot air drawing temperature is 120°C, and the drawing ratio is 1.2; the heat setting temperature is 120°C.

[0105] Example 4

[0106] A method for preparing high-strength, high-fog, transparent functional polylactic acid monofilament comprises the following steps:

[0107] (1) Primary granulation:

[0108] Poly(3-hydroxybutyrate) (PHB) and silver (Ag) powder with a particle size of 50 nm were placed in a high-speed mixer and premixed for 5 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 185° C. and a screw speed of 400 rpm to obtain PHB / Ag functional masterbatch chips; the obtained functional masterbatch chips were vacuum-dried at 80° C. for 48 hours and set aside;

[0109] (2) Secondary granulation:

[0110] The weight average molecular weight is 2.0×10 5 PLA with a D-LA content of 4.0 mol% and PHB / Ag functional masterbatch chips were placed in a high-speed mixer for premixing for 5 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 195° C. and a screw speed of 400 rpm to obtain PLA / PHB / Ag polylactic acid functional chips; the obtained polylactic acid functional chips were vacuum-dried at 90° C. for 24 hours and set aside;

[0111] (3) Preparation of high-strength, high-fog, transparent functional polylactic acid monofilaments:

[0112] PLA / PHB / Ag polylactic acid functional chips are used as raw materials, and PLA / PHB / Ag polylactic acid monofilaments are produced through melt horizontal spinning, melt extrusion, water bath cooling, hot steam stretching, hot air stretching, and heat setting.

[0113] Among them, the mass ratio of PLA, PHB, and Ag is 90:10:0.5;

[0114] The spinning temperature is 245°C, the first roller winding speed is 20m / min, and the water bath temperature is 60°C; the hot steam drawing temperature is 90°C, and the drawing ratio is 5.4; the second hot air drawing temperature is 120°C, and the drawing ratio is 1.2; the heat setting temperature is 120°C.

[0115] Example 5

[0116] A method for preparing high-strength, high-fog, transparent functional polylactic acid monofilament comprises the following steps:

[0117] (1) Primary granulation:

[0118] Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) having a 3-hydroxyhexanoate structural unit content of 12 mol% and ferric oxide (Fe2O3) nanoparticles having a particle size of 30 nm were placed in a high-speed mixer for premixing for 5 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 185° C. and a screw speed of 450 rpm to obtain PHBHHx / Fe2O3 functional masterbatch chips; the obtained functional masterbatch chips were vacuum-dried at 80° C. for 48 hours and set aside;

[0119] (2) Secondary granulation:

[0120] The weight average molecular weight is 2.0×10 5 PLA with a D-LA content of 4.0 mol% and PHBHHx / Fe2O3 functional masterbatch chips were placed in a high-speed mixer for premixing for 5 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 195° C. and a screw speed of 400 rpm to obtain PLA / PHBHHx / Fe2O3 polylactic acid functional chips; the obtained polylactic acid functional chips were vacuum-dried at 90° C. for 24 hours and set aside;

[0121] (3) Preparation of high-strength, high-fog, transparent functional polylactic acid monofilaments:

[0122] PLA / PHBHHx / Fe2O3 polylactic acid functional chips were used as raw materials and the PLA / PHBHHx / Fe2O3 polylactic acid monofilaments were prepared through melt horizontal spinning, melt extrusion, water bath cooling, hot steam stretching, hot air stretching and heat setting.

[0123] Among them, the mass ratio of PLA, PHBHHx, and Fe2O3 is 95:5:0.3;

[0124] The spinning temperature is 245°C, the first roller winding speed is 20m / min, and the water bath temperature is 70°C; the hot steam drawing temperature is 90°C, and the drawing ratio is 5.4; the second hot air drawing temperature is 100°C, and the drawing ratio is 1.2; the heat setting temperature is 120°C.

[0125] Example 6

[0126] A method for preparing high-strength, high-fog, transparent functional polylactic acid monofilament comprises the following steps:

[0127] (1) Primary granulation:

[0128] Polybutylene succinate (PBT) and cuprous oxide (Cu2O) were pre-mixed in a high-speed mixer for 5 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 240°C and a screw speed of 450 rpm to obtain PBT / Cu2O functional masterbatch chips; the obtained functional masterbatch chips were vacuum-dried at 100°C for 24 hours and set aside;

[0129] (2) Secondary granulation:

[0130] The weight average molecular weight is 2.2×10 5 PLA with a D-LA content of 0.25 mol% and PBT / Cu2O functional masterbatch chips were placed in a high-speed mixer for premixing for 5 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 235° C. and a screw speed of 450 rpm to obtain PLA / PBT / Cu2O polylactic acid functional chips; the obtained polylactic acid functional chips were vacuum-dried at 100° C. for 24 hours and set aside;

[0131] (3) Preparation of high-strength, high-fog, transparent functional polylactic acid monofilaments:

[0132] PLA / PBT / Cu2O polylactic acid functional chips were used as raw materials, and PLA / PBT / Cu2O polylactic acid monofilaments were prepared through melt horizontal spinning, melt extrusion, water bath cooling, hot steam stretching, hot air stretching, and heat setting.

[0133] Among them, the mass ratio of PLA, PBT, and Cu2O is 90:10:0.5;

[0134] The spinning temperature is 255°C, the first roller winding speed is 20m / min, the water bath temperature is 70°C; the hot steam drawing temperature is 90°C, and the drawing ratio is 5.4; the second hot air drawing temperature is 120°C, and the drawing ratio is 1.2; the heat setting temperature is 120°C.

[0135] Example 7

[0136] A method for preparing high-strength, high-fog, transparent functional polylactic acid monofilament comprises the following steps:

[0137] (1) Primary granulation:

[0138] Polycaprolactam (PA6) and TiO2 nanoparticles with a particle size of 30 nm were premixed in a high-speed mixer for 5 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 245°C and a screw speed of 450 rpm to obtain PA6 / TiO2 functional masterbatch chips; the obtained functional masterbatch chips were vacuum-dried at 100°C for 24 hours and set aside;

[0139] (2) Secondary granulation:

[0140] The weight average molecular weight is 2.2×10 5 PLA with a D-LA content of 0.25 mol% and PA6 / TiO2 functional masterbatch chips were placed in a high-speed mixer for premixing for 5 minutes, and then melt-blended and granulated in a twin-screw blender at a granulation temperature of 240°C and a screw speed of 450 rpm to obtain PLA / PA6 / TiO2 polylactic acid functional chips; the obtained polylactic acid functional chips were vacuum-dried at 100°C for 24 hours and set aside;

[0141] (3) Preparation of monofilament:

[0142] PLA / PA6 / TiO2 polylactic acid functional chips are used as raw materials, through melt horizontal spinning, melt extrusion - water bath cooling - hot steam stretching - hot air stretching - heat setting and other processes to produce PLA / PA6 / TiO2 polylactic acid monofilaments.

[0143] Among them, the mass ratio of PLA, PA6, and TiO2 is 90:10:0.5;

[0144] The spinning temperature is 245°C, the first roller winding speed is 20m / min, and the water bath temperature is 70°C; the hot steam drawing temperature is 90°C, and the drawing ratio is 5.4; the second hot air drawing temperature is 100°C, and the drawing ratio is 1.2; the heat setting temperature is 120°C.

[0145] The obtained monofilament was subjected to performance testing, and the test results are as follows:

[0146] Table 2 Test results

[0147] example Diameter (mm) Strength (cN / dtex) Elongation at break (%) Light transmittance (%) Haze (%) Spinnability Example 1 0.208 3.3 40.8 85 86 Good spinnability Example 2 0.198 3.2 38.2 84.5 85.3 Good spinnability Example 3 0.207 3.1 38.6 83.8 84.3 Good spinnability Example 4 0.196 2.7 40.2 83.6 84.2 Good spinnability Example 5 0.198 2.9 39.6 84.1 83.6 Good spinnability Example 6 0.210 3.2 37.3 81.3 86.3 Good spinnability Example 7 0.208 3.6 32.9 84.8 85.2 Good spinnability

[0148] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing high-strength, high-fog, transparent functional polylactic acid monofilament, characterized in that: The steps include: (1) Primary granulation: The high molecular weight polymer and inorganic nanoparticles are melt-blended and granulated to obtain functional masterbatch chips; Wherein, the high molecular weight polymer dispersion carrier is one of polypropylene, polyethylene, polyvinylidene fluoride, polytrimethylene terephthalate, polybutylene terephthalate, poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), polybutylene terephthalate-adipate, polybutylene succinate, nylon 12, nylon 11, polycaprolactam, nylon 1010, nylon 1212, and nylon 612; (2) Secondary granulation: The functional masterbatch slices are melt-blended and granulated with polylactic acid to obtain polylactic acid functional slices; (3) Preparation of monofilament: The polylactic acid functional chips are used as raw materials for melt spinning to obtain high-strength, high-fog and transparent functional polylactic acid monofilaments.

2. The method according to claim 1, characterized in that The mass ratio of polylactic acid, high molecular weight polymer and inorganic nanoparticles is 80-95:5-20:0.1-5; the weight average molecular weight of polylactic acid in step (2) is 1.0×10 5 ~6.0×10 6 ; The content of D-LA structural units in polylactic acid is 0% to 10 mol%.

3. The method according to claim 1, characterized in that The melt spinning in step (3) is a melt horizontal spinning, comprising melt extrusion - water bath cooling - hot steam stretching - hot air stretching - heat setting; Among them, the spinning temperature is 150-255°C, the first roller winding speed is 1-50m / min, the water bath temperature is 10-75°C; the hot steam drawing temperature is 75-95°C, and the drawing ratio is 2-6.5; the second hot air drawing temperature is 100-125°C, and the drawing ratio is 1.0-1.5; the heat setting temperature is 100-135°C.

4. The high-strength, high-fog, transparent functional polylactic acid monofilament prepared by the method according to any one of claims 1 to 3.

5. The high-strength, high-haze, transparent functional polylactic acid monofilament according to claim 4, characterized in that: The high molecular weight polymer dispersion carrier in the high-strength, high-fog, transparent functional polylactic acid monofilament exists in the form of microfibers with a diameter of no more than 700 nm.

6. A high-strength, high-fog, transparent functional polylactic acid yarn, characterized in that: It is prepared from the high-strength, high-fog, transparent functional polylactic acid monofilament described in claim 4.

7. A high-strength, high-fog, transparent functional polylactic acid fabric, characterized in that: It is prepared from the high-strength, high-fog, transparent functional polylactic acid monofilament described in claim 4.

8. An automobile interior, characterized in that: The high-strength, high-fog, transparent functional polylactic acid monofilament according to claim 4 is used for preparation.

9. Use of the high-strength, high-haze, transparent functional polylactic acid monofilament according to claim 4, the high-strength, high-haze, transparent functional polylactic acid yarn according to claim 6, and the high-strength, high-haze, transparent functional polylactic acid fabric according to claim 7 in the field of functional materials.

10. A method for improving the strength, haze and transparency of polylactic acid monofilaments, characterized in that: The steps include: (1) Primary granulation: The high molecular weight polymer and inorganic nanoparticles are melt-blended and granulated to obtain functional masterbatch chips; Wherein, the high molecular weight polymer dispersion carrier is one of polypropylene, polyethylene, polyvinylidene fluoride, polytrimethylene terephthalate, polybutylene terephthalate, poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), polybutylene terephthalate-adipate, polybutylene succinate, nylon 12, nylon 11, polycaprolactam, nylon 1010, nylon 1212, and nylon 612; (2) Secondary granulation: The functional masterbatch slices are melt-blended and granulated with polylactic acid to obtain polylactic acid functional slices; (3) Preparation of monofilament: The polylactic acid functional chips are used as raw materials for melt spinning to obtain high-strength, high-fog and transparent functional polylactic acid monofilaments.

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