Light-absorbing and heat-emitting polylactic acid fiber as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of textile fibers, and relates to a light-absorbing and heat-emitting polylactic acid fiber and a preparation method and application thereof. The preparation method of the polylactic acid fiber comprises the following steps: firstly, preparing the polylactic acid-based skin-core composite fiber, and then drying the polylactic acid-based skin-core composite fiber after the polylactic acid-based skin-core composite fiber sequentially passes through a weak acid bath, a weak alkali bath and a clear water bath to obtain the light-absorbing and heat-generating polylactic acid fiber. A skin layer component of the polylactic acid-based skin-core composite fiber is polylactic acid microporous master batch, and the polylactic acid microporous master batch is prepared from boron nitride, calcium carbonate, a dispersing agent and first polylactic acid with specific content; the core layer component of the polylactic acid-based sheath-core composite fiber comprises a light-absorbing heating material; and the pH value and temperature of the weak acid bath are strictly controlled. According to the application, the polylactic acid fiber is made into the light-absorbing and heat-emitting polylactic acid fabric. The light absorption and heating effect of the polylactic acid fiber is not attenuated due to friction / washing, the light absorption and heating efficiency is high, the somatosensory temperature rise effect is good, the dyeing performance is excellent, the fabric made of the polylactic acid fiber is suitable for the field of close-fitting warm-keeping textiles, and the application prospect is wide.

Description

Technical Field

[0001] This invention belongs to the field of textile fiber technology, and relates to a light-absorbing and heat-generating polylactic acid fiber, its preparation method and application. Background Technology

[0002] Polylactic acid fiber (PLA fiber) is a biodegradable fiber made from renewable plant resources (such as corn, sugarcane, cassava and other starch-containing crops) through fermentation, polymerization and spinning. It has both environmental protection properties and good wearability, and its application in the textile field, especially in underwear, has become increasingly widespread in recent years.

[0003] Light-absorbing and heat-generating fibers are a new type of textile fiber with energy conversion capabilities. They can actively absorb light energy and convert it into heat energy to achieve warmth. They can also be combined with heat-storing structures or reflect human body heat radiation to further enhance the warmth retention effect. Unlike traditional insulating fibers that only block heat loss, their core advantage lies in highly efficient heat absorption and insulation, allowing for lightweight design. Compared to traditional insulating materials, they are thinner, less bulky, and more comfortable to wear. However, currently available light-absorbing and heat-generating fibers have many shortcomings.

[0004] Patent application CN116988185A discloses a method for preparing light-absorbing and heat-generating polylactic acid (PLA) fibers, using tungsten bronze and / or antimony tin oxide as light-absorbing and heat-generating materials, resulting in fibers with a lighter color. This patent uses PLA and water-soluble polyesters of varying molecular weights as the fiber-forming polymer system. By controlling the fiber morphology and structure and water-soluble treatment, it prepares PLA fibers with grooved surfaces and rich in high-molecular-weight water-soluble polyesters, improving the fiber's photothermal conversion effect and dyeing properties. However, the increased surface area due to the grooves on the fiber surface makes it easy for the nanoscale light-absorbing material to be lost due to friction / washing, leading to a decrease in heat-generating performance.

[0005] Patent application CN116262990A discloses a light-absorbing and heat-generating warm polyester fiber and its preparation method. The fiber sheath is made of aerogel polyester, and the core layer includes light-absorbing and heat-generating polyester masterbatch and polyester. The sheath has an irregular structure and there is a hollow area between it and the core layer, which increases the hollowness of the fiber and improves the heat retention performance. It can avoid the problem of light-absorbing and heat-generating material loss due to friction / washing. However, it will reduce the light radiation energy reaching the core layer to a certain extent, limiting the improvement of the heating effect. Moreover, the aerogel layer of the sheath has a good heat transfer insulation effect, so the heat converted from light absorption inside the core layer cannot be effectively transferred to the human body, resulting in a decrease in the heating effect.

[0006] Patent application CN120608341A discloses a method for preparing a light-storing and heat-retaining polyester fiber. This fiber employs a core-sheath structure, with the core layer incorporating nanomaterials with broad infrared absorption rates, thus solving the problem of easy detachment of nanomaterials during friction / washing. The sheath layer uses PMDA and PBO-modified PET, improving the light absorption capacity of the sheath PET and avoiding the problem of reduced light radiation energy due to the core-sheath structure. However, the aromatic rings introduced by PMDA and PBO make the PET molecular chains more regular, promoting crystallization in some cases (especially since PBO itself is a highly crystalline polymer). This leads to a reduction in amorphous regions within the fiber, which are the "accommodation space" for dye molecules. Reducing this space directly decreases the dye uptake rate. Simultaneously, the π-π stacking effect between conjugated planes makes the PET molecular chains more tightly bound, increasing the resistance to dye molecule diffusion into the fiber and reducing the dyeing rate and saturation dye uptake.

[0007] Therefore, the preparation of a light-absorbing and heat-generating fiber with high light absorption and heat generation efficiency, good perceived temperature rise, light absorption and heat generation effect that does not decrease due to friction / washing, and good dyeing performance has important practical significance and application prospects.

[0008] Patent application CN110359129A discloses a method for preparing a multi-microporous core-sheath structure bicomponent composite fiber. This method forms a multi-microporous structure in the fiber sheath, improving the hydrophilicity and skin-friendliness of the bicomponent fiber through surface capillary effect. Simultaneously, the multi-micropore structure facilitates gas-liquid exchange between the core layer and the external environment, maximizing the practical effect of adding masterbatch to the core layer. However, if this existing technology is used to prepare a core-sheath composite fiber with a microporous sheath and a light-absorbing and heat-generating material in the core layer, it is difficult to achieve the characteristics of "high light-absorbing and heat-generating efficiency, good perceived temperature rise, light-absorbing and heat-generating effect not diminished by friction / washing, and good dyeing performance."

[0009] Because these existing technologies often use substances that decompose to produce gas when heated, soluble substances, and volatile substances with boiling points of 100-250℃ to create pores, they all suffer from uneven pore formation. Using sodium bicarbonate, ammonium chloride, and ammonium carbonate to generate gas for pore creation upon heating is problematic because these substances are temperature-sensitive and require precise temperature control (if the decomposition temperature of ammonium carbonate is too low, it is prone to premature decomposition during the mixing stage; if the decomposition temperature of ammonium chloride is too high, it may lead to thermal degradation of the fiber raw materials), making it extremely difficult to control the uniformity of pore formation. Using soluble substances such as glycerol, polyethylene glycol, and polyvinyl alcohol to dissolve in warm water for pore creation results in poor pore uniformity. Glycerol is a liquid, while polyethylene glycol and polyvinyl alcohol are solid particles that are prone to agglomeration, making it difficult to disperse evenly when mixed with fiber raw materials. After elution, irregular pores with a mixture of macropores and micropores are easily formed. Using volatile substances with boiling points between 100-250℃ for pore creation results in fluctuating evaporation rates. Even small temperature changes (such as ±10℃) can significantly alter the vapor pressure of these substances, leading to uneven evaporation rates and the problem of "no pores in early evaporation areas and collapsed pores in late evaporation areas." Furthermore, alcohols and alcohol ethers are mostly liquids, which easily penetrate or agglomerate when blended with fiber raw materials. When heated and volatilized, the substances may migrate to the fiber surface (rather than volatilizing in place), resulting in sparse internal pores, concentrated surface pores, and large differences in pore size. Poor pore uniformity directly affects light transmission and dye penetration, thereby affecting the light absorption and heat generation efficiency and dyeing performance of the final fabric.

[0010] In summary, although existing technologies provide various ideas and methods for preparing light-absorbing and heat-generating fibers, it is still difficult to simultaneously meet the comprehensive requirements of "high light-absorbing and heat-generating efficiency, good perceived temperature rise, light-absorbing and heat-generating effect not diminished by friction / washing, and good dyeing performance" when realizing sheath-core composite fibers with microporous structure in the sheath and light-absorbing and heat-generating material in the core. Summary of the Invention

[0011] The purpose of this invention is to solve the problems existing in the prior art and to provide a method for preparing light-absorbing and heat-generating polylactic acid fiber and its fabric, as well as its application.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] A method for preparing light-absorbing and heat-generating polylactic acid fiber involves first preparing polylactic acid-based sheath-core composite fiber, then sequentially passing the polylactic acid-based sheath-core composite fiber through a weak acid bath, a weak alkali bath, and a water bath before drying to obtain light-absorbing and heat-generating polylactic acid fiber.

[0014] The sheath component of the polylactic acid-based core-sheath composite fiber is polylactic acid microporous masterbatch, which, by weight, consists of 5-10 parts boron nitride, 5-15 parts calcium carbonate, 0-3 parts dispersant, and 72-90 parts primary polylactic acid.

[0015] The core layer component of polylactic acid-based sheath-core composite fiber includes light-absorbing and heat-generating materials;

[0016] The pH value of the weak acid bath should not be lower than 5.5, and the temperature should not be higher than 50°C.

[0017] The light-absorbing and heat-generating effect of the polylactic acid fiber of the present invention will not be reduced by friction / washing because the light-absorbing and heat-generating material is designed into the core layer of the fiber, avoiding direct contact between it and the outside world.

[0018] The light-absorbing and heat-generating polylactic acid (PLA) fiber of this invention exhibits high light-absorbing and heat-generating efficiency, good perceived temperature rise, and excellent dyeing properties. This is because, during the preparation process, the PLA-based sheath-core composite fiber contains a large amount of calcium carbonate and boron nitride in its sheath layer. Both of these substances are stable at PLA spinning temperatures and do not affect spinnability like substances that can decompose to produce gas, soluble substances, or volatile substances with boiling points between 100-250℃. During pore formation, calcium carbonate is dissolved in a weak acid bath. Setting the pH value of the weak acid bath to be no lower than 5.5 and the temperature to be no higher than 50℃ slows down the dissolution rate of calcium carbonate, which helps improve the uniformity of pore formation. In addition, boron nitride has a thermal conductivity effect, which can evenly transfer the heat from the weak acid bath. The uniform thermal effect further improves the uniformity of pore formation. Improving the uniformity of pore formation can enhance the light absorption and heat generation efficiency and dyeing performance of fibers. This is because: uniform micropores form "ordered light scattering channels" on the fiber surface. After light enters the pores, it undergoes multiple reflections between the pore walls, similar to "light traps," prolonging the residence time of light inside the fiber and significantly increasing the fiber's absorption probability of visible light and near-infrared rays. In particular, near-infrared rays account for more than 50% of the energy of sunlight and are the key source of fiber heat generation. The dyeing performance of fibers depends on whether dye molecules can efficiently and uniformly enter the fiber interior and be stably fixed. The uniform surface pore structure provides "ordered channels" for this process. It forms "consistent density and suitable size" adsorption sites on the fiber surface. Each pore has a similar adsorption capacity for dye, ensuring that the dye is evenly distributed on the fiber surface and avoiding problems such as color spots and white spots from the source. It also forms "continuous and interconnected" diffusion channels, guiding dye molecules to gradually diffuse from the fiber surface to the interior, prolonging the contact time between dye and fiber molecules, increasing the probability of covalent bonds, hydrogen bonds, and other binding between the two, and anchoring dye molecules to prevent dye escape caused by large pores. Ultimately, this improves the fiber dyeing rate and dyeing uniformity. In addition, boron nitride can transfer the heat generated by the light-absorbing and heat-generating material in the core layer to the human skin, further enhancing the perceived temperature rise.

[0019] This invention requires strict control of the proportions of boron nitride and calcium carbonate in the sheath component of polylactic acid-based core-sheath composite fibers. If the boron nitride content is too high, it will lead to severe boron nitride agglomeration. These agglomerated boron nitride particles will become "stress concentration points" during fiber spinning, causing fiber breakage, increased fuzz, and damage to the fiber's mechanical properties. Simultaneously, the agglomerated boron nitride particles will crowd out the dispersion space of calcium carbonate, resulting in uneven calcium carbonate distribution. Furthermore, large-sized boron nitride agglomerates may block the pores formed after calcium carbonate dissolution, causing a decrease in pore density. More seriously, the thermal conductivity of the boron nitride agglomeration region will be abnormally high, causing heat from the core layer to preferentially dissipate rapidly through the agglomerated region rather than being uniformly transferred to the fiber surface, thus reducing the overall light absorption and heat generation efficiency. If the boron nitride content is too low, the calcium carbonate on the fiber surface will not dissolve completely, resulting in a disordered pore structure. On the one hand, the disordered pore structure will lead to a decrease in light capture efficiency; on the other hand, insufficient boron nitride content will worsen the overall thermal conductivity of the skin layer, and the heat generated by the light-absorbing and heat-generating material in the core layer cannot be evenly transferred to the fiber surface, making it difficult to achieve a good perceived temperature rise. If the calcium carbonate content is too high, it will cause the pore structure to become uncontrolled and the fiber performance to collapse. After pore formation, the pore density will be too high and the pore volume will be too large. Adjacent pores will easily connect to form "through-pore macropores." The skin structure will become fragile due to excessive perforation, and the mechanical properties of the fiber will drop sharply. At the same time, it will increase the difficulty of dissolving in the weak acid bath, requiring a longer etching time or an increased acid concentration. Otherwise, the residual calcium carbonate will block the pores, leading to a decrease in dye uptake and an increase in dyeing unevenness. If the calcium carbonate content is too low, the surface fiber pore density will be insufficient and the light-trapping ability will be lacking. After pore formation, the pore density will be low and the pore volume will be small. There will be few channels on the fiber surface that can be used for "light traps". The light will escape after only a single reflection on the surface, and the near-infrared absorption efficiency will be greatly reduced. At the same time, low pore density means that there are few dye adsorption sites. The dye cannot fully adhere to the fiber surface, resulting in light and uneven color of the dyed finished product.

[0020] As a preferred technical solution:

[0021] In the above-described method for preparing light-absorbing and heat-generating polylactic acid fiber, the average sheet diameter of boron nitride is 1-2 μm and the average thickness is 1-10 nm; the average particle size of calcium carbonate is 70-90 nm; and the dispersant is one or more of ethylene bis-stearamide, ethylene-acrylic acid copolymer, and zinc salt ionomer of ethylene-acrylic acid copolymer.

[0022] As described above, the method for preparing light-absorbing and heat-generating polylactic acid fiber involves mixing the various components evenly in a high-speed mixer (500-1000 rpm, 5-20 min), and then granulating the mixture by melt extrusion (170-210℃) in a twin-screw extruder.

[0023] The method for preparing a light-absorbing and heat-generating polylactic acid fiber as described above, wherein, by weight, the core layer component of the polylactic acid-based sheath-core composite fiber consists of 90-99 parts of second polylactic acid and 1-10 parts of polylactic acid light-absorbing and heat-generating masterbatch;

[0024] By weight, polylactic acid light-absorbing and heat-generating masterbatch consists of 5-20 parts of light-absorbing and heat-generating material and 80-95 parts of third polylactic acid.

[0025] The light-absorbing and heat-generating polylactic acid fiber prepared as described above uses at least one of carbon nanotubes, copper sulfide, cesium tungsten bronze, and hafnium carbide as the light-absorbing and heat-generating material; the intrinsic viscosity of the first polylactic acid, the second polylactic acid, and the third polylactic acid is 0.68-0.70 dL / g.

[0026] The above-described method for preparing light-absorbing and heat-generating polylactic acid fiber involves mixing the various components evenly in a high-speed mixer (500-1000 rpm, 5-20 min), followed by melt extrusion (170-210℃) and granulation in a twin-screw extruder.

[0027] In the above-described method for preparing light-absorbing and heat-generating polylactic acid fiber, the weight ratio of the sheath component to the core component of the polylactic acid-based sheath-core composite fiber is 20-40:60-80.

[0028] In the above-described method for preparing light-absorbing and heat-generating polylactic acid fiber, the outer edge of the sheath of the polylactic acid-based core-sheath composite fiber is "circular", "trifoliate", "cross" or "pentafoliate", and the inner edge is "circular".

[0029] In the above-described method for preparing light-absorbing and heat-generating polylactic acid fiber, the pH value of the weak acid bath is not higher than 6.5, the temperature is not lower than 30℃, and the polylactic acid-based sheath-core composite fiber is immersed in the weak acid bath for 10-30 seconds.

[0030] The pH value of the weak alkaline bath is 7.5-8.5, the temperature is 30-50℃, and the polylactic acid-based sheath-core composite fiber is soaked in the weak alkaline bath for 10-30 seconds.

[0031] The temperature of the water bath is 30-50℃, and the polylactic acid-based core-sheath composite fiber is soaked in a weak alkaline bath for 60-120 seconds.

[0032] In the above-described method for preparing light-absorbing and heat-generating polylactic acid fiber, the weak acid bath is an aqueous solution of a weak acid, such as acetic acid, citric acid, or formic acid; the weak alkali bath is an aqueous solution of a weak alkali, such as ammonia, sodium bicarbonate, or triethanolamine.

[0033] This invention also provides a light-absorbing and heat-generating polylactic acid fiber, which is prepared by the method described in any one of the preceding claims. The surface of the light-absorbing and heat-generating polylactic acid fiber is distributed with micropores, the distribution density of which is 80-120 micropores / 2μm×2μm, the pore size range of which is 60-200nm, and the pore size variation coefficient is 3%-8%. The distribution density refers to the number of independent micropores in a 2μm×2μm observation area on the surface of the light-absorbing and heat-generating polylactic acid fiber, and the pore size variation coefficient is the ratio of the standard deviation of the pore size to the average pore size. The specifications of the light-absorbing and heat-generating polylactic acid fiber are 50-150D / 32-48f, and the breaking strength is 3.0-3.2cN / tex.

[0034] The present invention also provides an application of light-absorbing and heat-generating polylactic acid fiber as described above, wherein the light-absorbing and heat-generating polylactic acid fiber is sequentially weft-knitted and heat-set to produce a light-absorbing and heat-generating polylactic acid fabric.

[0035] As a preferred technical solution:

[0036] The application of light-absorbing and heat-generating polylactic acid fiber as described above involves a heat-setting temperature of 110-125℃, a time of 30-50s, and an overfeed rate of 3%-8%. The light-absorbing and heat-generating polylactic acid fabric has a warp density of 34-38 rows / cm, a weft density of 27-30 rows / cm, a disperse dye uptake rate of 95%-99%, a dyeing uniformity of 4-5 grades, a maximum temperature rise of 10.8-15.4℃ and an average temperature rise of 5.6-9.8℃ before 200 rubs and 20 washes, and a maximum temperature rise of 10.5-15.0℃ and an average temperature rise of 5.2-9.6℃ after 200 rubs and 20 washes.

[0037] Beneficial effects:

[0038] (1) The present invention designs the light-absorbing and heat-generating material in the core layer of polylactic acid-based core-sheath composite fiber to avoid direct contact with the outside world, so that the light-absorbing and heat-generating effect of the light-absorbing and heat-generating polylactic acid fiber will not be reduced by friction / washing.

[0039] (2) By strictly controlling the weight ratio of boron nitride and calcium carbonate in the cortex components and combining it with weak acid bath conditions, the calcium carbonate is slowly dissolved, and the thermal conductivity of boron nitride enables uniform heat transfer in the weak acid bath, which significantly improves the uniformity of pore formation. The uniform microporous structure is conducive to the efficient transmission of light, ensuring that the core light-absorbing and heat-generating material fully absorbs light, thereby improving the light-absorbing and heat-generating efficiency.

[0040] (3) The boron nitride in the skin layer component of the present invention has excellent thermal conductivity, which can quickly and evenly transfer the heat converted from light energy absorbed by the core light-absorbing and heat-generating material to the human skin, thereby improving the perceived temperature rise effect.

[0041] (4) The uniform micropores formed by the cortex of the present invention increase the specific surface area of ​​the fiber, providing more penetration channels and accommodation space for dye molecules, while avoiding the obstruction of dyeing by the cortex structure, thereby improving the dyeing performance of light-absorbing and heat-generating polylactic acid fiber. Detailed Implementation

[0042] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0043] To ensure that the performance of the substances used in each embodiment and comparative example is fully disclosed, the manufacturer information of the substances is specified in this invention; in addition, products from other manufacturers that conform to the limitations of this invention are also applicable.

[0044] The following are the test methods for the relevant performance indicators in each embodiment and comparative example:

[0045] Intrinsic viscosity: Tested in accordance with GB / T 14190-2008 "Test Methods for Fiber Grade Polyester Chips (PET)".

[0046] Linear density: Tested in accordance with GB / T 14343-2008 "Test Method for Linear Density of Chemical Fiber Filaments".

[0047] Tensile strength: Tested in accordance with GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments".

[0048] Disperse dye uptake rate and dyeing uniformity: The dye uptake rate of polylactic acid fabrics was tested according to GB / T 23976.1-2009 "Determination of Dye Uptake Rate Curve and Method for Determination of Color Uptake Rate"; (The last part, "GB / T," appears to be an error and is left untranslated.) Standard 6508-2015, "Test Method for Dyeing Uniformity of Polyester Filament," tests the dyeing uniformity of fabrics. The overall process employs a disperse dye high-temperature, high-pressure dyeing method, using Disperse Blue 60. The specific process is as follows: First, pretreatment is performed by adding 0.5-1 g / L of detergent, specifically fatty alcohol polyoxyethylene ether (manufacturer: Jiangsu Feixiang Chemical Co., Ltd., product number AEO-9). The treatment temperature is controlled at 60-70℃, the treatment time is 15-20 minutes, and the system pH is maintained at 6-7. Next, the dyeing bath is prepared. The amount of disperse dye is adjusted according to the color depth: 0.1-1% owf for light colors and 3-5% owf for dark colors. Simultaneously, 1-2 g / L of dispersant, specifically sodium naphthalenesulfonic acid formaldehyde condensate (manufacturer: Jiangsu Feixiang Chemical Co., Ltd., product number NNO), is added. Finally, 0.5-1 g / L of leveling agent, specifically fatty amine polyoxyethylene ether (manufacturer: Jiangsu Feixiang Chemical Co., Ltd.), is also added. The company (product number AC-1810) uses an acetate-sodium acetate buffer solution (acetic acid to sodium acetate volume ratio of 1:1) as a pH adjuster to adjust the pH of the staining bath to 4.5-5.5. Next, the staining is performed by raising the temperature. The initial temperature is set at 40-50℃, and after staining, the temperature is raised to 110-120℃ at a rate of 1-2℃ / min. After the temperature is raised, it is held at this temperature for 30-45min. The system pressure is maintained at 0.1-0.2MPa during the staining process. Finally, the post-treatment is performed by cooling. After staining, the temperature is lowered to below 60℃ at a rate of 1-2℃ / min, and then reduction cleaning is performed. A reduction cleaning solution is prepared, which contains 0.5-1g / L sodium hydrosulfite (manufacturer: Jiangsu Feixiang Chemical Co., Ltd., product number FX-8801) and 0.5g / L sodium hydroxide. The cleaning temperature is 60℃ and the cleaning time is 10-15min. After reduction cleaning, the product is washed with water and dried in sequence. The drying temperature does not exceed 80℃.

[0049] Maximum and average temperature rise before and after 200 rubbing cycles and 20 washing cycles: The fabric was rubbed 200 times according to ISO 105-X12-2016 "Textiles - Tests for color fastness - Part X12: Color fastness to rubbing" and washed 20 times according to ISO 105-C06-2010 "Textiles - Tests for color fastness - Part C06: Color fastness to domestic and commercial washing". The maximum and average temperature rise of the fabric were tested before and after rubbing and washing according to GB / T 18319-2019 "Textiles - Tests for light and heat storage properties".

[0050] Example 1

[0051] A method for preparing a light-absorbing and heat-generating polylactic acid fabric, the specific steps of which are as follows:

[0052] (1) Preparation of materials;

[0053] Boron nitride: average flake diameter is 1 μm, average thickness is 1 nm;

[0054] Calcium carbonate: average particle size is 80 nm;

[0055] Dispersant: Ethylene bis-stearamide;

[0056] First polylactic acid, second polylactic acid and third polylactic acid: The manufacturer is Anhui Fengyuan Futailai Polylactic Acid Co., Ltd., the grade is FY601, and the intrinsic viscosity is 0.68 dL / g;

[0057] Light-absorbing and heat-generating material: cesium tungsten bronze, manufactured by Xuancheng Jingrui New Materials Co., Ltd., product number JR-CW30;

[0058] Weak acid bath: Citric acid aqueous solution, pH 6, temperature 30℃;

[0059] Weak alkaline bath: sodium bicarbonate aqueous solution, pH 8, temperature 30℃;

[0060] Water bath: temperature 30℃;

[0061] (2) Preparation of polylactic acid-based sheath-core composite fiber;

[0062] The sheath component of the polylactic acid (PLA)-based core-sheath composite fiber is PLA microporous masterbatch. By weight, the PLA microporous masterbatch consists of 10 parts boron nitride, 10 parts calcium carbonate, 1 part dispersant, and 79 parts primary PLA. The PLA microporous masterbatch is obtained by uniformly mixing the components in a high-speed mixer (800 rpm, 10 min), followed by melt extrusion in a twin-screw extruder (screw zone 1 temperature: 190℃, screw zone 2 temperature: 210℃, screw zone 3 temperature: 210℃, screw zone 4 temperature: 210℃, screw zone 5 temperature: 200℃, screw zone 6 temperature: 200℃, screw zone 7 temperature: 190℃, screw zone 8 temperature: 170℃, screw zone 9 temperature: 170℃, screw zone 10 temperature: 190℃, screw zone 11 temperature: 200℃, screw zone 12 temperature: 210℃).

[0063] By weight, the core layer component of the polylactic acid (PLA)-based sheath-core composite fiber consists of 95 parts of second PLA and 5 parts of PLA light-absorbing and heat-generating masterbatch; by weight, the PLA light-absorbing and heat-generating masterbatch consists of 20 parts of light-absorbing and heat-generating material and 80 parts of third PLA; the PLA light-absorbing and heat-generating masterbatch is produced by uniformly mixing all components in a high-speed mixer (500 rpm, 5 min), followed by melt extrusion in a twin-screw extruder (screw zone 1). Granulation was performed at the following temperatures: screw zone 1: 190℃, screw zone 2: 210℃, screw zone 3: 210℃, screw zone 4: 210℃, screw zone 5: 200℃, screw zone 6: 200℃, screw zone 7: 190℃, screw zone 8: 170℃, screw zone 9: 170℃, screw zone 10: 190℃, screw zone 11: 200℃, screw zone 12: 210℃.

[0064] The weight ratio of the sheath component to the core component in the polylactic acid-based sheath-core composite fiber is 20:80; both the outer and inner edges of the sheath of the polylactic acid-based sheath-core composite fiber are "round" shaped.

[0065] (3) Preparation of light-absorbing and heat-generating polylactic acid fibers;

[0066] Polylactic acid-based core-sheath composite fibers are sequentially passed through a weak acid bath, a weak alkali bath, and a water bath, and then dried to obtain light-absorbing and heat-generating polylactic acid fibers. The polylactic acid-based core-sheath composite fibers are immersed in the weak acid bath for 20 seconds, in the weak alkali bath for 20 seconds, and in the water bath for 100 seconds.

[0067] The obtained light-absorbing and heat-generating polylactic acid (PLA) fiber has micropores distributed on its surface. The micropore density is 89 pores / 2μm×2μm, the micropore diameter ranges from 140 to 200 nm, and the micropore diameter variation coefficient is 8%. The distribution density refers to the number of independent micropores in a 2μm×2μm observation area on the surface of the light-absorbing and heat-generating PLA fiber. The micropore diameter variation coefficient is the ratio of the standard deviation of the micropore diameter to the average micropore diameter. The light-absorbing and heat-generating PLA fiber has a specification of 50D / 32f and a breaking strength of 3.0 cN / tex.

[0068] (4) Preparation of light-absorbing and heat-generating polylactic acid fabric;

[0069] The light-absorbing and heat-generating polylactic acid fibers are sequentially weft-knitted and heat-set to obtain the light-absorbing and heat-generating polylactic acid fabric; the heat-setting temperature is 125℃, the time is 30s, and the overfeed rate is 3%.

[0070] The final light-absorbing and heat-generating polylactic acid fabric has a warp density of 34 rows / cm and a weft density of 27 rows / cm. The disperse dye uptake rate is 95%, the dyeing uniformity is grade 4, the maximum temperature rise before 200 rubs and 20 washes is 14.9℃ and the average temperature rise is 9.6℃, and the maximum temperature rise after 200 rubs and 20 washes is 14.7℃ and the average temperature rise is 9.4℃.

[0071] Example 2

[0072] A method for preparing a light-absorbing and heat-generating polylactic acid fabric, the specific steps of which are as follows:

[0073] (1) Preparation of materials;

[0074] Boron nitride: average flake diameter is 1.5 μm, average thickness is 9 nm;

[0075] Calcium carbonate: average particle size is 70 nm;

[0076] Dispersant: Ethylene-acrylic acid copolymer, manufactured by Honeywell International, model AC®580;

[0077] First polylactic acid, second polylactic acid and third polylactic acid: manufactured by NatureWorks LLC, grade 6201D, intrinsic viscosity 0.70 dL / g;

[0078] Light-absorbing and heat-generating material: copper sulfide, manufactured by Zhejiang Yamei Nanotechnology Co., Ltd., item number AM-CuS-506-1;

[0079] Weak acid bath: Citric acid aqueous solution, pH 5.5, temperature 40℃;

[0080] Weak alkaline bath: sodium bicarbonate aqueous solution, pH 8.5, temperature 40℃;

[0081] Water bath: temperature 50℃;

[0082] (2) Preparation of polylactic acid-based sheath-core composite fiber;

[0083] The sheath component of the polylactic acid (PLA)-based core-sheath composite fiber is PLA microporous masterbatch. By weight, the PLA microporous masterbatch consists of 10 parts boron nitride, 15 parts calcium carbonate, 3 parts dispersant, and 72 parts primary PLA. The PLA microporous masterbatch is obtained by uniformly mixing the components in a high-speed mixer (1000 rpm, 20 min), followed by melt extrusion in a twin-screw extruder (screw zone 1 temperature: 190℃, screw zone 2 temperature: 210℃, screw zone 3 temperature: 210℃, screw zone 4 temperature: 210℃, screw zone 5 temperature: 200℃, screw zone 6 temperature: 200℃, screw zone 7 temperature: 190℃, screw zone 8 temperature: 170℃, screw zone 9 temperature: 170℃, screw zone 10 temperature: 190℃, screw zone 11 temperature: 200℃, screw zone 12 temperature: 210℃) granulation.

[0084] By weight, the core layer component of the polylactic acid (PLA)-based core-sheath composite fiber consists of 99 parts of second PLA and 1 part of PLA light-absorbing and heat-generating masterbatch; by weight, the PLA light-absorbing and heat-generating masterbatch consists of 5 parts of light-absorbing and heat-generating material and 95 parts of third PLA; the PLA light-absorbing and heat-generating masterbatch is produced by uniformly mixing all components in a high-speed mixer (700 rpm, 10 min), followed by melt extrusion in a twin-screw extruder (screw zone one). Granulation was performed at the following temperatures: screw zone 1: 190℃, screw zone 2: 210℃, screw zone 3: 210℃, screw zone 4: 210℃, screw zone 5: 200℃, screw zone 6: 200℃, screw zone 7: 190℃, screw zone 8: 170℃, screw zone 9: 170℃, screw zone 10: 190℃, screw zone 11: 200℃, screw zone 12: 210℃.

[0085] The weight ratio of the sheath component to the core component in polylactic acid-based sheath-core composite fiber is 30:70; the outer edge of the sheath of the polylactic acid-based sheath-core composite fiber is "cross" shaped, and the inner edge is "round" shaped;

[0086] (3) Preparation of light-absorbing and heat-generating polylactic acid fibers;

[0087] Polylactic acid-based core-sheath composite fibers are sequentially passed through a weak acid bath, a weak alkali bath, and a water bath, and then dried to obtain light-absorbing and heat-generating polylactic acid fibers. The polylactic acid-based core-sheath composite fibers are immersed in the weak acid bath for 30 seconds, in the weak alkali bath for 30 seconds, and in the water bath for 60 seconds.

[0088] The obtained light-absorbing and heat-generating polylactic acid (PLA) fiber has micropores distributed on its surface. The micropore density is 114 micropores / 2μm×2μm, the micropore size ranges from 90 to 140 nm, and the micropore size variation coefficient is 7%. The distribution density refers to the number of independent micropores in a 2μm×2μm observation area on the surface of the light-absorbing and heat-generating PLA fiber. The micropore size variation coefficient is the ratio of the standard deviation of the micropore size to the average micropore size. The light-absorbing and heat-generating PLA fiber has a specification of 75D / 36f and a breaking strength of 3.1 cN / tex.

[0089] (4) Preparation of light-absorbing and heat-generating polylactic acid fabric;

[0090] The light-absorbing and heat-generating polylactic acid fibers are sequentially weft-knitted and heat-set to obtain the light-absorbing and heat-generating polylactic acid fabric; the heat-setting temperature is 110℃, the time is 40s, and the overfeed rate is 5%.

[0091] The final light-absorbing and heat-generating polylactic acid fabric has a longitudinal density of 35 rows / cm and a transverse density of 28 rows / cm. The disperse dye uptake rate is 96%, the dyeing uniformity is grade 5, the maximum temperature rise before 200 rubs and 20 washes is 10.8℃ and the average temperature rise is 5.6℃, and the maximum temperature rise after 200 rubs and 20 washes is 10.5℃ and the average temperature rise is 5.2℃.

[0092] Example 3

[0093] A method for preparing a light-absorbing and heat-generating polylactic acid fabric, the specific steps of which are as follows:

[0094] (1) Preparation of materials;

[0095] Boron nitride: average flake diameter is 1 μm, average thickness is 5 nm;

[0096] Calcium carbonate: average particle size is 90 nm;

[0097] Dispersant: Zinc salt ionomer of ethylene-acrylic acid copolymer, manufactured by Honeywell International, model AClyn®295A;

[0098] First polylactic acid, second polylactic acid and third polylactic acid: manufactured by Zhejiang Hisun Biomaterials Co., Ltd., brand name REVODE190, intrinsic viscosity 0.69 dL / g;

[0099] Light-absorbing and heat-generating material: carbon nanotubes, manufactured by Shanghai Dazhan Times Nano Technology Co., Ltd., product number GC-21;

[0100] Weak acid bath: formic acid aqueous solution, pH 5.8, temperature 50℃;

[0101] Weak alkaline bath: triethanolamine aqueous solution, pH 8.2, temperature 50℃;

[0102] Water bath: temperature 30℃;

[0103] (2) Preparation of polylactic acid-based sheath-core composite fiber;

[0104] The sheath component of the polylactic acid (PLA)-based core-sheath composite fiber is PLA microporous masterbatch. By weight, the PLA microporous masterbatch consists of 8 parts boron nitride, 5 parts calcium carbonate, 1.5 parts dispersant, and 85.5 parts primary PLA. The PLA microporous masterbatch is obtained by uniformly mixing the components in a high-speed mixer (500 rpm, 5 min), followed by melt extrusion in a twin-screw extruder (screw zone 1 temperature: 190℃, screw zone 2 temperature: 210℃, screw zone 3 temperature: 210℃, screw zone 4 temperature: 210℃, screw zone 5 temperature: 200℃, screw zone 6 temperature: 200℃, screw zone 7 temperature: 190℃, screw zone 8 temperature: 170℃, screw zone 9 temperature: 170℃, screw zone 10 temperature: 190℃, screw zone 11 temperature: 200℃, screw zone 12 temperature: 210℃) granulation.

[0105] By weight, the core layer component of the polylactic acid (PLA)-based sheath-core composite fiber consists of 90 parts of second PLA and 10 parts of PLA light-absorbing and heat-generating masterbatch; by weight, the PLA light-absorbing and heat-generating masterbatch consists of 15 parts of light-absorbing and heat-generating material and 85 parts of third PLA; the PLA light-absorbing and heat-generating masterbatch is produced by uniformly mixing all components in a high-speed mixer (800 rpm, 10 min), followed by melt extrusion in a twin-screw extruder (screw one...). Granulation was performed using the following temperature zones: Zone 1: 190℃, Zone 2: 210℃, Zone 3: 210℃, Zone 4: 210℃, Zone 5: 200℃, Zone 6: 200℃, Zone 7: 190℃, Zone 8: 170℃, Zone 9: 170℃, Zone 10: 190℃, Zone 11: 200℃, Zone 12: 210℃.

[0106] The weight ratio of the sheath component to the core component in polylactic acid-based sheath-core composite fiber is 35:65; the outer edge of the sheath of the polylactic acid-based sheath-core composite fiber is "trefoil" shaped, and the inner edge is "circle" shaped.

[0107] (3) Preparation of light-absorbing and heat-generating polylactic acid fibers;

[0108] Polylactic acid-based core-sheath composite fibers are sequentially passed through a weak acid bath, a weak alkali bath, and a water bath, and then dried to obtain light-absorbing and heat-generating polylactic acid fibers. The polylactic acid-based core-sheath composite fibers are immersed in the weak acid bath for 10 seconds, in the weak alkali bath for 10 seconds, and in the water bath for 120 seconds.

[0109] The obtained light-absorbing and heat-generating polylactic acid (PLA) fiber has micropores distributed on its surface. The micropore density is 80 micropores / 2μm×2μm, the micropore size ranges from 160 to 180 nm, and the micropore size variation coefficient is 3%. The distribution density refers to the number of independent micropores in a 2μm×2μm observation area on the surface of the light-absorbing and heat-generating PLA fiber. The micropore size variation coefficient is the ratio of the standard deviation of the micropore size to the average micropore size. The specifications of the light-absorbing and heat-generating PLA fiber are 75D / 48f, and the tensile strength is 3.14 cN / tex.

[0110] (4) Preparation of light-absorbing and heat-generating polylactic acid fabric;

[0111] The light-absorbing and heat-generating polylactic acid fiber is sequentially weft-knitted and heat-set to obtain the light-absorbing and heat-generating polylactic acid fabric; the heat-setting temperature is 117℃, the time is 50s, and the overfeed rate is 6%.

[0112] The final light-absorbing and heat-generating polylactic acid fabric has a warp density of 36 rows / cm and a weft density of 28 rows / cm. The disperse dye uptake rate is 99%, the dyeing uniformity is grade 4.5, the maximum temperature rise before 200 rubs and 20 washes is 15.4℃ and the average temperature rise is 9.8℃, and the maximum temperature rise after 200 rubs and 20 washes is 15.0℃ and the average temperature rise is 9.6℃.

[0113] Example 4

[0114] A method for preparing a light-absorbing and heat-generating polylactic acid fabric, the specific steps of which are as follows:

[0115] (1) Preparation of materials;

[0116] Boron nitride: average flake diameter is 2 μm, average thickness is 3 nm;

[0117] Calcium carbonate: average particle size is 76 nm;

[0118] Dispersant: A mixture of ethylene bis-stearamide and ethylene acrylic acid copolymer (manufacturer: Honeywell International, model AC®580) in a mass ratio of 1:1;

[0119] First polylactic acid, second polylactic acid and third polylactic acid: The manufacturer is Anhui Fengyuan Futailai Polylactic Acid Co., Ltd., the grade is FY601, and the intrinsic viscosity is 0.68 dL / g;

[0120] Light-absorbing and heat-generating material: Hafnium carbide, manufactured by Zhejiang Yamei Nanotechnology Co., Ltd., product number AM-HfC-001-1;

[0121] Weak acid bath: acetic acid aqueous solution, pH 6.5, temperature 35℃;

[0122] Weak alkaline bath: sodium bicarbonate aqueous solution, pH 7.5, temperature 35℃;

[0123] Water bath: temperature 40℃;

[0124] (2) Preparation of polylactic acid-based sheath-core composite fiber;

[0125] The sheath component of the polylactic acid (PLA)-based core-sheath composite fiber is PLA microporous masterbatch. By weight, the PLA microporous masterbatch consists of 10 parts boron nitride, 8 parts calcium carbonate, 1 part dispersant, and 81 parts primary PLA. The PLA microporous masterbatch is obtained by uniformly mixing the components in a high-speed mixer (500 rpm, 10 min), followed by melt extrusion in a twin-screw extruder (screw zone 1 temperature: 190℃, screw zone 2 temperature: 210℃, screw zone 3 temperature: 210℃, screw zone 4 temperature: 210℃, screw zone 5 temperature: 200℃, screw zone 6 temperature: 200℃, screw zone 7 temperature: 190℃, screw zone 8 temperature: 170℃, screw zone 9 temperature: 170℃, screw zone 10 temperature: 190℃, screw zone 11 temperature: 200℃, screw zone 12 temperature: 210℃) granulation.

[0126] By weight, the core layer component of the polylactic acid (PLA)-based sheath-core composite fiber consists of 94 parts of second PLA and 6 parts of PLA light-absorbing and heat-generating masterbatch; by weight, the PLA light-absorbing and heat-generating masterbatch consists of 13 parts of light-absorbing and heat-generating material and 87 parts of third PLA. The PLA light-absorbing and heat-generating masterbatch is produced by uniformly mixing all components in a high-speed mixer (500 rpm, 20 min) and then melt-extruding it in a twin-screw extruder (screw zone 1). Granulation was performed at the following temperatures: screw zone 1: 190℃, screw zone 2: 210℃, screw zone 3: 210℃, screw zone 4: 210℃, screw zone 5: 200℃, screw zone 6: 200℃, screw zone 7: 190℃, screw zone 8: 170℃, screw zone 9: 170℃, screw zone 10: 190℃, screw zone 11: 200℃, screw zone 12: 210℃.

[0127] The weight ratio of the sheath component to the core component in polylactic acid-based sheath-core composite fiber is 40:60; the outer edge of the sheath of the polylactic acid-based sheath-core composite fiber is "five-leaf" shaped, and the inner edge is "round" shaped;

[0128] (3) Preparation of light-absorbing and heat-generating polylactic acid fibers;

[0129] Polylactic acid-based core-sheath composite fibers are sequentially passed through a weak acid bath, a weak alkali bath, and a water bath, and then dried to obtain light-absorbing and heat-generating polylactic acid fibers. The polylactic acid-based core-sheath composite fibers are immersed in the weak acid bath for 20 seconds, in the weak alkali bath for 20 seconds, and in the water bath for 90 seconds.

[0130] The obtained light-absorbing and heat-generating polylactic acid (PLA) fiber has micropores distributed on its surface. The micropore density is 100 micropores / 2μm×2μm, the micropore diameter ranges from 110 to 150 nm, and the micropore diameter variation coefficient is 6%. The distribution density refers to the number of independent micropores in a 2μm×2μm observation area on the surface of the light-absorbing and heat-generating PLA fiber. The micropore diameter variation coefficient is the ratio of the standard deviation of the micropore diameter to the average micropore diameter. The specifications of the light-absorbing and heat-generating PLA fiber are 100D / 36f, and the tensile strength is 3.05 cN / tex.

[0131] (4) Preparation of light-absorbing and heat-generating polylactic acid fabric;

[0132] The light-absorbing and heat-generating polylactic acid fibers are sequentially weft-knitted and heat-set to obtain the light-absorbing and heat-generating polylactic acid fabric; the heat-setting temperature is 118℃, the time is 40s, and the overfeed rate is 4%.

[0133] The final light-absorbing and heat-generating polylactic acid fabric has a warp density of 37 rows / cm and a weft density of 29 rows / cm. The disperse dye uptake rate is 97%, the dyeing uniformity is grade 4, the maximum temperature rise before 200 rubs and 20 washes is 14.0℃ and the average temperature rise is 8.6℃, and the maximum temperature rise after 200 rubs and 20 washes is 13.7℃ and the average temperature rise is 9.4℃.

[0134] Example 5

[0135] A method for preparing a light-absorbing and heat-generating polylactic acid fabric, the specific steps of which are as follows:

[0136] (1) Preparation of materials;

[0137] Boron nitride: average flake diameter is 1.5 μm, average thickness is 10 nm;

[0138] Calcium carbonate: average particle size is 83 nm;

[0139] Dispersant: A mixture of zinc salt ionomer of ethylene bis-stearamide and ethylene acrylic acid copolymer (manufacturer: Honeywell International, model AClyn® 295A) in a mass ratio of 1:1;

[0140] First polylactic acid, second polylactic acid and third polylactic acid: The manufacturer is Anhui Fengyuan Futailai Polylactic Acid Co., Ltd., the grade is FY601, and the intrinsic viscosity is 0.68 dL / g;

[0141] Light-absorbing and heat-generating material: cesium tungsten bronze, manufactured by Xuancheng Jingrui New Materials Co., Ltd., product number JR-CW30;

[0142] Weak acid bath: formic acid aqueous solution, pH 6.3, temperature 40℃;

[0143] Weak alkaline bath: triethanolamine aqueous solution, pH 7.7, temperature 40℃;

[0144] Water bath: temperature 35℃;

[0145] (2) Preparation of polylactic acid-based sheath-core composite fiber;

[0146] The sheath component of the polylactic acid (PLA)-based core-sheath composite fiber is PLA microporous masterbatch. By weight, the PLA microporous masterbatch consists of 5 parts boron nitride, 5 parts calcium carbonate, and 90 parts polylactic acid (PLA). The PLA microporous masterbatch is obtained by uniformly mixing the components in a high-speed mixer (700 rpm, 20 min), followed by melt extrusion in a twin-screw extruder (screw zone 1 temperature: 190℃, screw zone 2 temperature: 210℃, screw zone 3 temperature: 210℃, screw zone 4 temperature: 210℃, screw zone 5 temperature: 200℃, screw zone 6 temperature: 200℃, screw zone 7 temperature: 190℃, screw zone 8 temperature: 170℃, screw zone 9 temperature: 170℃, screw zone 10 temperature: 190℃, screw zone 11 temperature: 200℃, screw zone 12 temperature: 210℃) granulation.

[0147] By weight, the core layer component of the polylactic acid (PLA)-based sheath-core composite fiber consists of 97 parts of second PLA and 3 parts of PLA light-absorbing and heat-generating masterbatch; by weight, the PLA light-absorbing and heat-generating masterbatch consists of 7 parts of light-absorbing and heat-generating material and 93 parts of third PLA. The PLA light-absorbing and heat-generating masterbatch is produced by uniformly mixing all components in a high-speed mixer (1000 rpm, 20 min), followed by melt extrusion in a twin-screw extruder (screw zone 1). Granulation was performed at the following temperatures: screw zone 1: 190℃, screw zone 2: 210℃, screw zone 3: 210℃, screw zone 4: 210℃, screw zone 5: 200℃, screw zone 6: 200℃, screw zone 7: 190℃, screw zone 8: 170℃, screw zone 9: 170℃, screw zone 10: 190℃, screw zone 11: 200℃, screw zone 12: 210℃.

[0148] The weight ratio of the sheath component to the core component in polylactic acid-based sheath-core composite fiber is 25:75; both the outer and inner edges of the sheath of the polylactic acid-based sheath-core composite fiber are "round".

[0149] (3) Preparation of light-absorbing and heat-generating polylactic acid fibers;

[0150] Polylactic acid-based core-sheath composite fibers are sequentially passed through a weak acid bath, a weak alkali bath, and a water bath, and then dried to obtain light-absorbing and heat-generating polylactic acid fibers. The polylactic acid-based core-sheath composite fibers are immersed in the weak acid bath for 10 seconds, in the weak alkali bath for 10 seconds, and in the water bath for 100 seconds.

[0151] The obtained light-absorbing and heat-generating polylactic acid (PLA) fiber has micropores distributed on its surface. The micropore density is 120 micropores / 2μm×2μm, the micropore diameter ranges from 60 to 90 nm, and the micropore diameter variation coefficient is 4%. The distribution density refers to the number of independent micropores in a 2μm×2μm observation area on the surface of the light-absorbing and heat-generating PLA fiber. The micropore diameter variation coefficient is the ratio of the standard deviation of the micropore diameter to the average micropore diameter. The specifications of the light-absorbing and heat-generating PLA fiber are 150D / 48f, and the tensile strength is 3.2 cN / tex.

[0152] (4) Preparation of light-absorbing and heat-generating polylactic acid fabric;

[0153] The light-absorbing and heat-generating polylactic acid fiber is sequentially weft-knitted and heat-set to obtain the light-absorbing and heat-generating polylactic acid fabric; the heat-setting temperature is 120℃, the time is 35s, and the overfeed rate is 8%.

[0154] The final light-absorbing and heat-generating polylactic acid fabric has a warp density of 38 rows / cm and a weft density of 30 rows / cm. The disperse dye uptake rate is 95%, the dyeing uniformity is grade 4, the maximum temperature rise before 200 rubs and 20 washes is 13.1℃ and the average temperature rise is 7.7℃, and the maximum temperature rise after 200 rubs and 20 washes is 12.8℃ and the average temperature rise is 7.4℃.

[0155] Comparative Example 1

[0156] A method for preparing polylactic acid fabric differs from Example 2 only in that: the pH value of the weak acid bath is 5; in the product of step (3), the distribution density of micropores is 125 / 2μm×2μm, the pore size range of micropores is 98-165nm, and the pore size variation coefficient of micropores is 16%; the tensile strength of the product of step (3) is 2.98cN / tex.

[0157] The final polylactic acid fabric had a disperse dye uptake rate of 93%, a dyeing uniformity of 3.5, a maximum temperature rise of 8.4℃ and an average temperature rise of 3.7℃ before 200 rubs and 20 washes, and a maximum temperature rise of 8.0℃ and an average temperature rise of 3.1℃ after 200 rubs and 20 washes.

[0158] Compared with Comparative Example 1 and Example 2, the micropore size variation coefficient of the light-absorbing and heat-generating polylactic acid fiber was significantly increased, the breaking strength was significantly reduced, and the disperse dye uptake rate, dyeing uniformity, and maximum and average temperature rise before and after rubbing and washing of the fabric were significantly reduced. This is because the pH value of the weak acid bath in Comparative Example 1 was too low, which accelerated the dissolution rate of calcium carbonate, resulting in a significant decrease in pore uniformity. This not only damaged the structural integrity of the fiber, but also prevented the formation of "ordered light scattering channels" and uniform dye penetration channels on the fiber surface, thereby affecting the mechanical properties, light-absorbing and heat-generating efficiency, and dyeing performance of the fiber.

[0159] Comparative Example 2

[0160] A method for preparing polylactic acid fabric differs from Example 3 only in that: the temperature of the weak acid bath is 60°C; in the product of step (3), the distribution density of micropores is 92 / 2μm×2μm, the pore size range of micropores is 165-198nm, and the pore size variation coefficient of micropores is 14%; the tensile strength of the product of step (3) is 2.94cN / tex.

[0161] The final polylactic acid fabric had a disperse dye uptake rate of 91%, a dyeing uniformity of 3.5, a maximum temperature rise of 13.5℃ and an average temperature rise of 8.0℃ before 200 rubs and 20 washes, and a maximum temperature rise of 13.0℃ and an average temperature rise of 7.4℃ after 200 rubs and 20 washes.

[0162] Compared with Comparative Example 2 and Example 3, the micropore size variation coefficient of light-absorbing and heat-generating polylactic acid fiber was significantly increased and the breaking strength was significantly reduced. The disperse dye uptake rate, dyeing uniformity and temperature rise value of the fabric were significantly reduced. This is because the weak acid bath temperature in Comparative Example 2 was too high, which accelerated the dissolution of calcium carbonate, resulting in the loss of control of the pore-forming process. The micropore distribution was disordered and the pore size difference was large. This not only weakened the light-harvesting ability and dye adsorption and diffusion ability of the fiber, but also destroyed the cortex structure of the fiber, resulting in a significant decrease in the mechanical properties of the fiber and the core properties of the subsequent fabric.

[0163] Comparative Example 3

[0164] A method for preparing polylactic acid fabric differs from Example 1 only in that calcium carbonate is replaced with polyethylene glycol (manufacturer: Dow Chemical Company, model: PEG 8000); in the product of step (3), the distribution density of micropores is 126 / 2μm×2μm, the pore size range of micropores is 10-420nm, and the pore size variation coefficient of micropores is 35%; the tensile strength of the product of step (3) is 2.42cN / tex.

[0165] The final polylactic acid fabric had a disperse dye uptake rate of 83%, a dyeing uniformity of 2.5, a maximum temperature rise of 7.8℃ and an average temperature rise of 2.1℃ before 200 rubs and 20 washes, and a maximum temperature rise of 4.9℃ and an average temperature rise of 1.1℃ after 200 rubs and 20 washes.

[0166] Compared with Example 1, Comparative Example 3 showed a significantly larger coefficient of variation in micropore size and a substantial decrease in breaking strength in polylactic acid (PLA) fibers that absorbed light and generated heat. The dye uptake rate, dyeing uniformity, and temperature rise of the fabric were also significantly reduced. This is because Comparative Example 3 used polyethylene glycol instead of calcium carbonate for pore formation. As a soluble pore-forming agent, polyethylene glycol tends to agglomerate when blended with fiber raw materials, forming irregular pores with a mixture of macropores and micropores after washing, resulting in extremely poor pore uniformity. At the same time, polyethylene glycol pore formation cannot be optimized by utilizing the thermal conductivity of boron nitride, further exacerbating the disorder of the pore structure. This leads to severe damage to the light scattering channels and dye penetration channels on the fiber surface, destroying the integrity of the fiber structure, and ultimately causing a fundamental deterioration in light absorption and heat generation performance, dyeing performance, and mechanical properties.

Claims

1. A method for preparing light-absorbing and heat-generating polylactic acid fiber, characterized in that, First, polylactic acid-based sheath-core composite fiber is prepared. Then, the polylactic acid-based sheath-core composite fiber is passed through a weak acid bath, a weak alkali bath, and a water bath in sequence and then dried to obtain light-absorbing and heat-generating polylactic acid fiber. The sheath component of the polylactic acid-based core-sheath composite fiber is polylactic acid microporous masterbatch, which, by weight, consists of 5-10 parts boron nitride, 5-15 parts calcium carbonate, 0-3 parts dispersant, and 72-90 parts primary polylactic acid. The core layer component of polylactic acid-based sheath-core composite fiber includes light-absorbing and heat-generating materials; The pH value of the weak acid bath should not be lower than 5.5, and the temperature should not be higher than 50℃.

2. The method for preparing light-absorbing and heat-generating polylactic acid fiber according to claim 1, characterized in that, The average particle size of boron nitride is 1-2 μm and the average thickness is 1-10 nm; the average particle size of calcium carbonate is 70-90 nm.

3. The method for preparing light-absorbing and heat-generating polylactic acid fiber according to claim 1, characterized in that, By weight, the core layer component of polylactic acid-based sheath-core composite fiber consists of 90-99 parts of second polylactic acid and 1-10 parts of polylactic acid light-absorbing and heat-generating masterbatch; By weight, polylactic acid light-absorbing and heat-generating masterbatch consists of 5-20 parts of light-absorbing and heat-generating material and 80-95 parts of third polylactic acid.

4. The method for preparing light-absorbing and heat-generating polylactic acid fiber according to claim 3, characterized in that, The light-absorbing and heat-generating material is at least one of carbon nanotubes, copper sulfide, cesium tungsten bronze, and hafnium carbide; the intrinsic viscosity of the first polylactic acid, the second polylactic acid, and the third polylactic acid is 0.68-0.70 dL / g.

5. The method for preparing light-absorbing and heat-generating polylactic acid fiber according to claim 1, characterized in that, The weight ratio of the sheath component to the core component in polylactic acid-based sheath-core composite fibers is 20-40:60-80.

6. The method for preparing light-absorbing and heat-generating polylactic acid fiber according to claim 1, characterized in that, The outer edge of the sheath of polylactic acid-based core-sheath composite fiber is "circular", "trifoliate", "cross" or "pentafoliate", while the inner edge is "circular".

7. The method for preparing light-absorbing and heat-generating polylactic acid fiber according to claim 1, characterized in that, The pH value of the weak acid bath should not be higher than 6.5, the temperature should not be lower than 30℃, and the polylactic acid-based sheath-core composite fiber should be soaked in the weak acid bath for 10-30 seconds. The pH value of the weak alkaline bath is 7.5-8.5, the temperature is 30-50℃, and the polylactic acid-based sheath-core composite fiber is soaked in the weak alkaline bath for 10-30 seconds. The temperature of the water bath is 30-50℃, and the polylactic acid-based sheath-core composite fiber is soaked in a weak alkaline bath for 60-120 seconds. A weak acid bath is an aqueous solution of a weak acid, such as acetic acid, citric acid, or formic acid; a weak base bath is an aqueous solution of a weak base, such as ammonia, sodium bicarbonate, or triethanolamine.

8. A light-absorbing and heat-generating polylactic acid fiber, characterized in that, The light-absorbing and heat-generating polylactic acid (PLA) fiber is prepared by any one of claims 1-7. The surface of the PLA fiber is distributed with micropores, the micropore density is 80-120 pores / 2μm×2μm, the micropore diameter range is 60-200nm, and the micropore diameter variation coefficient is 3%-8%. The distribution density refers to the number of independent micropores within a 2μm×2μm observation area on the surface of the PLA fiber, and the pore diameter variation coefficient is the ratio of the standard deviation of the pore diameter to the average pore diameter. The PLA fiber has a specification of 50-150D / 32-48f and a breaking strength of 3.0-3.2cN / tex.

9. The application of a light-absorbing and heat-generating polylactic acid fiber as described in claim 8, characterized in that, The light-absorbing and heat-generating polylactic acid fibers are sequentially weft-knitted and heat-set to produce light-absorbing and heat-generating polylactic acid fabric.

10. The application of a light-absorbing and heat-generating polylactic acid fiber according to claim 9, characterized in that, The heat setting temperature is 110-125℃, the time is 30-50s, and the overfeed rate is 3%-8%. The light-absorbing and heat-generating polylactic acid fabric has a warp density of 34-38 rows / cm and a weft density of 27-30 rows / cm. The disperse dye uptake rate is 95%-99%, the dyeing uniformity is grade 4-5, the maximum temperature rise before 200 rubs and 20 washes is 10.8-15.4℃ and the average temperature rise is 5.6-9.8℃, and the maximum temperature rise after 200 rubs and 20 washes is 10.5-15.0℃ and the average temperature rise is 5.2-9.6℃.