Blended yarn with photochromic performance and preparation method thereof

Abstract

The invention belongs to the technical field of textile materials, and particularly relates to blended yarn with photochromic performance and a preparation method of the blended yarn. Common yarns are generally stable in mechanical property, such as good strength and wear resistance, while the photochromic fibers prepared by the method have unique optical response characteristics. After the photochromic fiber and the photochromic fiber are twisted, the common yarn can solve the problem of low mechanical strength of the photochromic fiber, and the overall durability of the yarn is enhanced; and the photochromic fibers endow the common yarn with a function of generating color response to illumination change, so that the combination of functionality and practicability is realized, and the application range of the yarn is expanded. The novel photochromic yarn meets the requirements of different fields for multifunctional materials, and opens up a new market space. In the fields of safety protection, stage performance, artistic creation and the like, the sales channel and the application field of yarn products are widened.

Description

Technical Field

[0001] The present invention belongs to the technical field of textile materials, and particularly relates to a blended yarn with photochromic properties and a preparation method thereof. Background Art

[0002] Traditional yarns have a single function and cannot change color with the change of light. Existing photochromic materials are mostly used in coatings or films, and are less applied in the textile field. Moreover, there are problems such as non-persistent color change effect and poor wash resistance. Photochromic materials can undergo reversible color changes under light, and are widely used in fields such as textiles, coatings, and cosmetics. In recent years, with the development of intelligent textiles, photochromic blended yarns have become a research hotspot. Photochromic blended yarns combine the advantages of photochromic fibers and ordinary fibers, having both the color-changing function and maintaining good mechanical properties and comfort. By adjusting the blending ratio and process, the color-changing effect and durability of the yarn can be optimized.

[0003] At present, people's awareness of environmental protection is constantly increasing, and biodegradable polymer materials made from renewable resources have received more and more attention. Polyhydroxyalkanoates (PHA) are storage substances of intracellular energy and carbon sources synthesized by various bacteria under unbalanced nutritional conditions. Their raw material sources are very rich, getting rid of the dependence on non-renewable fossil raw materials. They are a class of biobased polymers with excellent biodegradability and biocompatibility, and are considered to be future green polymers together with polylactic acid (PLA) and polybutylene succinate. After more than a decade of development, PHA has been studied for many applications in fields such as biology, medicine, plastics, and packaging, but the research in the textile field is relatively less, and the spun fibers are relatively brittle. Conventional PHA has a low nucleation density and slow crystal growth, making it difficult to form fibers. Preparing PHA blend fibers by blending modification is a cost-effective and relatively direct method.

[0004] Currently, the related research on PHA derivatives with photochromic properties has not been utilized. To expand the application of PHA fibers, a novel yarn is obtained by twisting the fibers prepared by blending PHA, PLA, and photochromic microcapsules with ordinary yarns, improving the durability and practicality of the yarn. In addition, by blending a yarn with a constant color and a photochromic yarn, on the one hand, the stable and unchanging color of the constant-color yarn itself is utilized, and on the other hand, the property that the photochromic fiber is sensitive to light and can change color is utilized. At the same time, by changing the proportional relationship of the two components, many possibilities of color combinations can be obtained. For example, a yarn with green is used as the base color material, and the number of strands of the fiber with photochromic properties (changing from white to yellow or green) is changed and blended with it. The colors of the fibers are combined through the color mixing principle, and a series of color-changing yarns in the yellow-green color system can be obtained, providing the possibility of invisibility in backgrounds such as deserts, meadows, and forests.

[0005] The invention of the CN116288799A patent belongs to the field of regenerated seaweed functional fiber composites and relates to a preparation method of photochromic seaweed fibers and yarns, which includes the following steps: 1) Prepare tungsten trioxide nanoparticles in different ways and configure them into a mixture with water according to the mass ratio; 2) Add glycerol and a dispersant to the mixture in step 1) and mix and stir to obtain a clear solution; 3) Mix and stir the sodium alginate aqueous solution with the clear solution obtained in step 2), and then perform defoaming treatment to obtain a spinning solution; 4) Extrude the spinning solution in step 3), solidify it into filaments through a coagulation bath in sequence and shape it through a stretching bath, wash and dry the shaped fibers obtained to obtain the photochromic seaweed fibers. 5) Obtain yarns from the photochromic seaweed fibers in step 4) by using a spinning process. This method not only retains the original advantages of seaweed fibers and tungsten trioxide, but also has a simple preparation process and low cost, and can be applied to the textile field. Although glycerol and a dispersant are added during the preparation process, the tungsten trioxide nanoparticles may still be unevenly dispersed in the system, resulting in inconsistent photochromic properties of the final fibers and yarns. For example, the color change is obvious in some areas, while it is not obvious or the color change speed is slow in some areas. Although tungsten trioxide, as a photochromic inorganic material, has good thermal stability and fatigue resistance, in practical applications, when the photochromic seaweed fibers and yarns are exposed to environmental factors such as light, temperature, and humidity for a long time, the combination of tungsten trioxide and sodium alginate may gradually weaken, resulting in a gradual decline in photochromic properties, such as a decrease in color change sensitivity and a shortening of the color change duration.

[0006] To solve the problem of photochromic stability, photochromic microcapsules are used as the color-changing material. The photochromic microcapsules encapsulate active ingredients such as photochromic dyes inside, isolating them from the external environment, which can prevent the dyes from being directly exposed to the air, reduce the contact with oxygen, moisture, etc., and lower the occurrence probability of reactions such as oxidation and hydrolysis, thereby improving the stability of the photochromic material under different environmental conditions and ensuring that the color-changing properties of the fibers and yarns are not easily affected during long-term use and storage. Moreover, PHA and PLA have good compatibility with the photochromic microcapsules. They can be evenly mixed with the microcapsules to form a stable structure in the fibers and yarns, enabling the photochromic microcapsules to be evenly dispersed in the matrix and avoiding the agglomeration or phase separation of the microcapsules, thereby ensuring the uniformity and stability of the photochromic properties. Summary of the Invention

[0007] Due to the poor thermal stability of PHA materials, with the melting point and decomposition temperature being close, the processing temperature window is narrow, the melting point is low, the cooling rate is slow, and the phenomenon of filament merging is prone to occur. Therefore, if the melt spinning method is used for spinning, the process is difficult and the temperature control requirements are strict. As a type of wet spinning, the microfluidic spinning method can achieve the spinning process at room temperature without considering the melting point of the material, facilitating the adjustment of various parameters in spinning. Moreover, the microfluidic spinning method can obtain continuous PHA / PLA fibers. By adding photochromic microcapsules to the spinning solution, since the microcapsules will not be damaged by the spinning solution and will not affect the continuity of spinning, PHA / PLA fibers with photochromic functions can also be prepared.

[0008] Existing photochromic blended yarns have insufficient mechanical properties. In actual use, problems such as breakage, pilling, etc. are prone to occur, and they cannot meet some application scenarios with high requirements for yarn strength and wear resistance. In this patent, the mechanical properties of photochromic fibers have been improved, and their strength can meet normal daily use. After blending with ordinary yarns, the design and manufacture of fabrics can be completed.

[0009] There may be differences in the mechanical properties such as strength, elongation, elasticity, etc. between photochromic PHA / PLA fibers and ordinary yarns. Therefore, it is necessary to improve the mechanical properties of the fibers to enhance their durability and better meet the actual needs.

[0010] There are a large number of color options for ordinary yarns. Therefore, it is necessary to increase the various color effects of photochromic fibers to make the color effects of photochromic blended yarns have countless possibilities.

[0011] To solve the above existing technical problems, the present application provides the following technical solutions:

[0012] The present invention provides a method for preparing a blended yarn with photochromic properties, including the following steps:

[0013] S11: Mix organic solvent A containing polyhydroxyalkanoate (PHA) and organic solvent B containing polylactic acid (PLA) to obtain a PHA / PLA spinning solution;

[0014] S12: Add one or more photochromic microcapsules prepared from different photochromic solutions to the PHA / PLA spinning solution and mix to obtain a spinning solution; the photochromic microcapsules are obtained by heating and reacting an aqueous solution containing a melamine formaldehyde resin prepolymer, an O / W emulsion, and a dispersant under acidic conditions; the melamine formaldehyde resin prepolymer is obtained by reacting melamine and formaldehyde under high temperature and alkaline conditions, and the O / W emulsion is obtained by reacting a photochromic solution and an aqueous solution containing sodium dodecyl sulfate;

[0015] S13: Perform microfluidic spinning on the above to obtain photochromic PHA / PLA fibers;

[0016] S14: Parallelly arrange the photochromic PHA / PLA fibers and the colored yarns, then ply and twist them to obtain the blended yarn with photochromic properties.

[0017] Preferably, the organic solvent A is chloroform, and the organic solvent B is dichloromethane.

[0018] Preferably, the volume ratio of the organic solvent A containing polyhydroxyalkanoate (PHA) to the organic solvent B containing polylactic acid (PLA) is 1:2.

[0019] Preferably, the organic solvent A containing polyhydroxyalkanoate (PHA) is obtained by adding polyhydroxyalkanoate to the organic solvent A, stirring at 60 °C for 6 h, and then standing for 30 min; the concentration of the solute is 2 wt%; the organic solvent B containing polylactic acid (PLA) is obtained by adding polylactic acid to the organic solvent B and stirring at room temperature for 6 h; the concentration of the solute is 10 - 16 wt%.

[0020] Specifically, 1) Weigh 1 g of PHA powder and 49 g of chloroform solution respectively to prepare a 2 wt% PHA / chloroform solution. Place the solution in an oil bath and heat it to 60 °C, and stir for 6 h until all the solute is dissolved, then stand for 30 min to defoam, and a uniform, transparent PHA solution with a certain viscosity can be obtained. 2) Weigh 6 g of PLA particles and place them in 44 g of dichloromethane solution respectively. Stir the solution with a magnetic stirrer at room temperature for 6 h to obtain a transparent and homogeneous PLA solution.

[0021] Preferably, in the step S12, the mixing method is to stir at room temperature for 3 h and then stand for 30 min to defoam.

[0022] Preferably, the dispersant is polyvinyl alcohol (PVA), and the concentration of PVA during the heating reaction is 0.2 wt%.

[0023] Preferably, the temperature of the heating reaction is 65 - 75 °C, and the time is 2 - 4 h.

[0024] Preferably, the temperature of the high-temperature reaction is 65 - 75 °C, and the time is 0.5 - 1.5 h.

[0025] Preferably, the temperature of the reaction between the photochromic solution and the aqueous solution containing sodium dodecyl sulfate (SDS) is 55 - 65 °C, and the time is 30 - 50 min.

[0026] Preferably, the photochromic solution is selected from a tetrachloroethylene solution of spirooxazine, a dichloromethane solution of naphthopyran, or a n-octane solution of spiropyran.

[0027] Preferably, in the step S13, the method of microfluidic spinning is as follows: sucking the spinning solution into a syringe, adjusting the propulsion speed by an injection pump, allowing the spinning solution to enter a coagulation bath of ethanol, fixing and forming the fibers, and then collecting and winding them by a drum-type collecting device, and naturally drying them.

[0028] Preferably, in the step S13, the spinning speed of the microfluidic spinning is 2 - 5 mL / min.

[0029] Specifically, 0.1 g of photochromic powder is weighed and added to 9.9 g of PHA / PLA spinning solution respectively, and stirred at room temperature for 3 h to fully disperse the microcapsules in the spinning solution, and then left standing for 30 min to defoam to obtain the spinning solution. The spinning solution is sucked into a syringe by the microfluidic spinning method, the propulsion speed is adjusted by an injection pump, the spinning speed is 2 - 5 mL / min, the spinning solution enters a coagulation bath of absolute ethanol, the fibers are fixed and formed, and then collected and wound by a drum-type collecting device, and the photochromic PHA / PLA fibers can be obtained after natural drying.

[0030] Preferably, in the step S14, the ratio of the parallel arrangement of the photochromic PHA / PLA fibers and the colored yarns is 2 - 3:1.

[0031] Preferably, in the step S14, the twisting speed is 500 - 2000 rpm.

[0032] In the present invention, the photochromic fibers with the best mechanical properties and optical properties prepared are arranged in parallel with ordinary yarns in a certain ratio (2 - 3 fibers and one ordinary yarn are used in the present invention), introduced into a drawframe, and preliminarily combined together. The drawframe speed and tension should be controlled well in this step to ensure that the tensions of the two kinds of yarns are uniform, and avoid uneven thickness of the yarns after twisting due to tension differences. The drawn yarns are introduced into a twisting device, and the twist and tension of the yarns should be continuously monitored during the twisting process to ensure stable twisting quality, and finally the yarns with photochromic effect are obtained.

[0033] The present invention also provides a blended yarn with photochromic properties prepared by the above preparation method.

[0034] The technical solution of the present invention has the following advantages compared with the prior art:

[0035] The relevant research on the yarns with photochromic properties has not been reported yet. Combining PHA fibers with photochromic materials can expand the application fields of PHA fibers.

[0036] Physically combining PHA with other biodegradable polymer materials to produce complementary advantages is an important step in the development of PHA fibers. PLA is a non-toxic and harmless biodegradable material. Mixing PLA with PHA can improve the mechanical properties of PHA fibers, increasing their strength and elongation at break. The spun fibers and yarns have excellent biocompatibility and biodegradability.

[0037] Ordinary yarns usually have stable mechanical properties, such as good strength and wear resistance, while the photochromic fibers prepared in this invention have unique optical response characteristics. After they are twisted together, the ordinary yarns can make up for the problem of low mechanical strength of the photochromic fibers, enhancing the overall durability of the yarns; the photochromic fibers endow the ordinary yarns with the function of color response to light changes, achieving the combination of functionality and practicality and expanding the application scope of the yarns.

[0038] This new type of photochromic yarn meets the needs of different fields for multifunctional materials, opening up new market space. For example, in the field of safety protection, using its photochromic properties to make warning signs or clothing can more prominently warn of dangers under different lighting conditions; in the fields of stage performances, artistic creations, etc., it can also play a role with its unique color-changing effects, thus broadening the sales channels and application fields of yarn products. Description of the Drawings

[0039] Figure 1 Figure for comparison before illumination of the photochromic yarn prepared by mixing ordinary yarn with PCM1 and PCM2 in Example 1;

[0040] Figure 2 Figure for comparison after illumination of the photochromic yarn prepared by mixing ordinary yarn with PCM1 and PCM2 in Example 1;

[0041] Figure 3 Figure for comparison before illumination of the photochromic yarn prepared by mixing ordinary yarn with PCM2 in Example 5;

[0042] Figure 4 Figure for comparison after illumination of the photochromic yarn prepared by mixing ordinary yarn with PCM2 in Example 5. Detailed Description of the Invention

[0043] The following further illustrates the present invention in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the cited embodiments do not limit the present invention.

[0044] The preparation methods of the three-primary-color photochromic microcapsules used in each embodiment are as follows:

[0045] (1) Synthesis of melamine formaldehyde resin prepolymer

[0046] Add 7 g of melamine powder, 12 mL of 37 wt% formaldehyde solution and 24 mL of deionized water into a three-necked flask equipped with a condensing reflux device, and mix and stir. Adjust the pH value of the reaction system to 8 - 9 (using 2 wt% NaOH solution), and at the same time heat it in an oil bath to raise the temperature to 70 °C, and react for 1 h (500 rpm). After the melamine is completely dissolved, a clear and transparent melamine formaldehyde resin prepolymer solution can be obtained.

[0047] (2) Preparation of O / W emulsion

[0048] Measure 10 mL of a 0.75 wt% photochromic solution as the oil phase (spirooxazine dissolved in tetrachloroethylene / naphthopyran dissolved in dichloromethane / spiropyran dissolved in n-octane), and slowly pour it into a round-bottom flask containing a certain volume (15 mL) and concentration of sodium dodecyl sulfate (SDS) solution, and stir with a mechanical stirrer for a certain time (1000 rpm, 40 min, 60 °C) to obtain a stable O / W emulsion.

[0049] Spirooxazine dissolved in tetrachloroethylene / naphthopyran dissolved in dichloromethane / spiropyran dissolved in n-octane are three core materials, corresponding to PCM1 (blue), PCM2 (yellow), and PCM3 (red) respectively.

[0050] (3) Encapsulation reaction

[0051] Drop the melamine formaldehyde resin prepolymer solution prepared in the first step into the O / W emulsion prepared in the second step. And add a 0.2 wt% concentration of dispersant polyvinyl alcohol (PVA) solution. Adjust the pH value of the reaction system to about 6.0, and stir at a certain speed at room temperature for 30 min. Then, adjust the pH value of the reaction system to about 5.0, and at the same time heat it in an oil bath to raise the temperature to 70 °C, and react for 3 h. After the reaction is completed, ultrasonically disperse the sample in absolute ethanol, centrifuge with a high-speed centrifuge, wash 3 times, and heat and dry (60 °C, 6 h) to obtain photochromic microcapsules.

[0052] Example 1

[0053] Use a 2 wt% PHA / chloroform solution as part of the spinning solution. Weigh 1 g of PHA powder and 49 g of chloroform solution respectively to prepare a 2 wt% PHA / chloroform solution. Place the solution in an oil bath and heat it to 60 °C, and stir for 6 h until all the solute is dissolved and let it stand for 30 min to defoam, then a uniform, transparent and viscous PHA solution can be obtained.

[0054] It is necessary to prepare a PLA / dichloromethane solution with a mass concentration of 10 wt%. Weigh 5 g of PLA particles and place them in 45 g of dichloromethane solution respectively. Stir the solution at room temperature with a magnetic stirrer for 6 h to obtain a transparent and homogeneous PLA solution. Mix the prepared PHA and PLA solutions in a volume ratio of 1:2 to obtain a homogeneous PHA / PLA solution.

[0055] Weigh 0.05 g of blue photochromic microcapsules (PCM1) and 0.05 g of yellow photochromic microcapsules (PCM2), pour them into the PHA / PLA solution, put in a rotor of appropriate size, and label the sample name on the bottle body and the bottle cap. Place it on a magnetic stirrer, adjust the rotation speed to 400 r / min, stir for 4 h, then remove it from the magnetic stirrer and let it stand at room temperature for 30 min to obtain a spinning solution that can spin green color-changing fibers.

[0056] Add the spinning solution prepared in the previous step into a 10 mL syringe, adopt a microfluidic spinning speed of 3 mL / min, and the spinning solution enters the coagulation bath of anhydrous ethanol. The solvent in the spinning solution exchanges with the non-solvent in the coagulation bath, making the fibers solidify and take shape. Then, it is collected and wound by a drum-type collecting device, and can be obtained photochromic PHA / PLA fibers after natural drying.

[0057] Place the photochromic fibers and ordinary colored yarns on the unwinding rack or creel respectively, and control the parallel arrangement of multiple fibers through yarn guides and tensioners. The tension of the photochromic fibers is 0.2 cN / dtex, and the tension of the ordinary colored yarn is 0.3 cN / dtex. Set the twist range to 1200 twists / meter, and synchronously transport them to the twisting zone through yarn rollers. Twist the photochromic fibers (2 pieces) and the ordinary colored yarn at 1000 rpm. Check whether the plied yarn after doubling is uniform to avoid uneven tightness or entanglement.

[0058] Example 2

[0059] Use a 2 wt% PHA / chloroform solution as part of the spinning solution. Weigh 1 g of PHA powder and 49 g of chloroform solution respectively to prepare a 2 wt% PHA / chloroform solution. Place the solution in an oil bath and heat it to 60 °C, and stir for 6 h until all the solute is dissolved and let it stand for 30 min to defoam, then a uniform, transparent and viscous PHA solution can be obtained.

[0060] It is necessary to prepare a PLA / dichloromethane solution with a mass concentration of 12 wt%. Weigh 6 g of PLA particles and place them in 44 g of dichloromethane solution respectively. Stir the solution at room temperature for 6 h with a magnetic stirrer to obtain a transparent and homogeneous PLA solution. Mix the prepared PHA and PLA solutions in a volume ratio of 1:2 to obtain a homogeneous PHA / PLA solution.

[0061] Weigh 0.05 g of blue photochromic microcapsules (PCM1) and 0.05 g of yellow photochromic microcapsules (PCM2) and pour them into the PHA / PLA solution. Place a rotor of appropriate size and label the sample name on the bottle body and the bottle cap. Put it on a magnetic stirrer, adjust the rotation speed to 400 r / min, stir for 4 h, then remove it from the magnetic stirrer and let it stand at room temperature for 30 min to obtain a spinning solution that can spin green color-changing fibers.

[0062] Add the spinning solution prepared in the previous step into a 10 mL syringe. The microfluidic spinning speed used is 3 mL / min. The spinning solution enters the coagulation bath of absolute ethanol. The solvent in the spinning solution exchanges with the non-solvent in the coagulation bath, causing the fibers to solidify and take shape. Then, it is collected and wound by a drum-type collecting device and naturally dried to obtain photochromic PHA / PLA fibers.

[0063] Place the photochromic fibers and ordinary colored yarns on a unwinding rack or a creel respectively, and control the parallel arrangement of multiple fibers through a yarn guide hook and a tensioner. The tension of the photochromic fibers is 0.2 cN / dtex, and the tension of the ordinary colored yarn is 0.3 cN / dtex. Set the twist range to 1200 twists per meter and synchronously transport them to the twisting zone through a yarn guide roller. Twist the photochromic fibers (2 pieces) and the ordinary colored yarn at 1000 rpm. Check whether the plied yarn after doubling is uniform to avoid uneven tightness or entanglement.

[0064] Example 3

[0065] Use a 2 wt% PHA / chloroform solution as part of the spinning solution. Weigh 1 g of PHA powder and 49 g of chloroform solution respectively to prepare a 2 wt% PHA / chloroform solution. Place the solution in an oil bath and heat it to 60 °C, and stir for 6 h until all the solute is dissolved and let it stand for 30 min to defoam, then a uniform, transparent and viscous PHA solution can be obtained.

[0066] It is necessary to prepare a PLA / dichloromethane solution with a mass concentration of 14 wt%. Weigh 7 g of PLA particles and place them in 43 g of dichloromethane solution respectively. Stir the solution at room temperature with a magnetic stirrer for 6 h to obtain a transparent and homogeneous PLA solution. Mix the prepared PHA and PLA solutions in a volume ratio of 1:2 to obtain a homogeneous PHA / PLA solution.

[0067] Weigh 0.05 g of blue photochromic microcapsules (PCM1) and 0.05 g of yellow photochromic microcapsules (PCM2), pour them into the PHA / PLA solution, put in a rotor of appropriate size, and label the sample name on the bottle body and the bottle cap. Place it on a magnetic stirrer, adjust the rotation speed to 400 r / min, stir for 4 h, then remove it from the magnetic stirrer and let it stand at room temperature for 30 min to obtain a spinning solution that can spin green color-changing fibers.

[0068] Add the spinning solution prepared in the previous step into a 10 mL syringe, and adopt a microfluidic spinning speed of 3 mL / min. The spinning solution enters the coagulation bath of anhydrous ethanol, and an exchange occurs between the solvent in the spinning solution and the non-solvent in the coagulation bath, causing the fibers to solidify and take shape. Then, it is collected and wound by a drum-type collecting device, and can be obtained photochromic PHA / PLA fibers after natural drying.

[0069] Place the photochromic fibers and ordinary colored yarns on a unwinding rack or a creel respectively, and control the parallel arrangement of multiple fibers through a yarn guide hook and a tensioner. The tension of the photochromic fibers is 0.2 cN / dtex, and the tension of the ordinary colored yarns is 0.3 cN / dtex. Set the twist range to 1200 twists / meter, and synchronously transport them to the twisting zone through a yarn guide roller. Twist the photochromic fibers (2 pieces) and the ordinary colored yarns at 1000 rpm. Check whether the plied yarn after doubling is uniform to avoid uneven tightness or entanglement.

[0070] Example 4

[0071] Use a 2 wt% PHA / chloroform solution as part of the spinning solution. Weigh 1 g of PHA powder and 49 g of chloroform solution respectively to prepare a PHA / chloroform solution with a concentration of 2 wt%. Place the solution in an oil bath and heat it to 60 °C, and stir for 6 h until all the solute is dissolved and let it stand for 30 min to defoam, then a uniform, transparent and viscous PHA solution can be obtained.

[0072] It is necessary to prepare a PLA / dichloromethane solution with a mass concentration of 16 wt%. Weigh 8 g of PLA particles and place them in 42 g of dichloromethane solution respectively. Stir the solution at room temperature with a magnetic stirrer for 6 h to obtain a transparent and homogeneous PLA solution. Mix the prepared PHA and PLA solutions in a volume ratio of 1:2 to obtain a homogeneous PHA / PLA solution.

[0073] Weigh 0.05 g of blue photochromic microcapsules (PCM1) and 0.05 g of yellow photochromic microcapsules (PCM2), pour them into the PHA / PLA solution, put in a rotor of appropriate size, and label the sample name on the bottle body and the bottle cap. Place it on a magnetic stirrer, adjust the rotation speed to 400 r / min, stir for 4 h, then remove it from the magnetic stirrer and let it stand at room temperature for 30 min to obtain a spinning solution that can spin green color-changing fibers.

[0074] Add the spinning solution prepared in the previous step into a 10 mL syringe. The microfluidic spinning speed used is 3 mL / min. The spinning solution enters the coagulation bath of absolute ethanol. The solvent in the spinning solution exchanges with the non-solvent in the coagulation bath, causing the fibers to solidify and take shape. Then it is collected and wound by a drum-type collecting device and naturally dried to obtain photochromic PHA / PLA fibers.

[0075] Place the photochromic fibers and ordinary colored yarns on a creel or a bobbin rack respectively, and control the parallel arrangement of multiple fibers through a yarn guide hook and a tensioner. The tension of the photochromic fibers is 0.2 cN / dtex, and the tension of the ordinary colored yarns is 0.3 cN / dtex. Set the twist range to 1200 twists / meter and synchronously transport them to the twisting zone through a yarn guide roller. Twist the photochromic fibers (2 pieces) and the ordinary colored yarns at 1000 rpm. Check whether the plied yarn after doubling is uniform to avoid uneven tightness or entanglement.

[0076] Example 5

[0077] Use a 2 wt% PHA / chloroform solution as part of the spinning solution. Weigh 1 g of PHA powder and 49 g of chloroform solution respectively to prepare a 2 wt% PHA / chloroform solution. Place the solution in an oil bath and heat it to 60 °C, and stir for 6 h until all the solute is dissolved and let it stand for 30 min to defoam, then a uniform, transparent and viscous PHA solution can be obtained.

[0078] It is necessary to prepare a PLA / dichloromethane solution with a mass concentration of 14 wt%. Weigh 7 g of PLA particles and place them in 43 g of dichloromethane solution respectively. Stir the solution with a magnetic stirrer at room temperature for 6 h to obtain a transparent and homogeneous PLA solution. Mix the prepared PHA and PLA solutions in a volume ratio of 1:2 to obtain a homogeneous PHA / PLA solution.

[0079] Weigh 0.1 g of yellow photochromic microcapsules PCM2 and pour them into the above-mentioned PHA / PLA solution. Place a rotor of appropriate size and label the sample name on the bottle body and the bottle cap. Place it on a magnetic stirrer, adjust the rotation speed to 400 rpm, stir for 4 h, then remove it from the magnetic stirrer and let it stand at room temperature for 30 min to obtain a spinning solution that can spin green color-changing fibers.

[0080] Add the spinning solution prepared in the previous step into a 10 mL syringe. The microfluidic spinning speed used is 2 mL / min. The spinning solution enters the coagulation bath of anhydrous ethanol, and an exchange occurs between the solvent in the spinning solution and the non-solvent in the coagulation bath, causing the fibers to solidify and take shape. Then, it is collected and wound by a drum-type collecting device and naturally dried to obtain photochromic PHA / PLA fibers.

[0081] Place the photochromic fibers and ordinary colored yarns on a creel or a bobbin rack respectively, and control the parallel arrangement of multiple fibers through a yarn guide hook and a tensioner. The tension of the photochromic fibers is 0.1 cN / dtex, and the tension of the ordinary colored yarns is 0.2 cN / dtex. Set the twist range to 800 twists per meter and synchronously transport them to the twisting zone through a yarn guide roller. Twist the photochromic fibers (2 pieces) and the ordinary colored yarns at 500 rpm. Check whether the plied yarn after doubling is uniform to avoid uneven tightness or entanglement.

[0082] Example 6

[0083] Use a 2 wt% PHA / chloroform solution as part of the spinning solution. Weigh 1 g of PHA powder and 49 g of chloroform solution respectively to prepare a 2 wt% PHA / chloroform solution. Place the solution in an oil bath and heat it to 60 °C, and stir for 6 h until all the solute is dissolved and let it stand for 30 min to defoam, then a homogeneous, transparent and viscous PHA solution can be obtained.

[0084] It is necessary to prepare a PLA / dichloromethane solution with a mass concentration of 14 wt%. Weigh 7 g of PLA particles and place them in 43 g of dichloromethane solution respectively. Stir the solution with a magnetic stirrer at room temperature for 6 h to obtain a transparent and homogeneous PLA solution. Mix the prepared PHA and PLA solutions in a volume ratio of 1:2 to obtain a homogeneous PHA / PLA solution.

[0085] Weigh 0.1 g of the yellow photochromic microcapsule PCM2 and pour it into the above-mentioned PHA / PLA solution. Place a rotor of appropriate size and label the sample name on the bottle body and the bottle cap. Place it on a magnetic stirrer, adjust the rotation speed to 400 revolutions per minute, stir for 4 h, then remove it from the magnetic stirrer and let it stand at room temperature for 30 min to obtain a spinning solution that can spin out green color-changing fibers.

[0086] Add the spinning solution prepared in the previous step into a 10 mL syringe. The microfluidic spinning speed used is 5 mL / min. The spinning solution enters the coagulation bath of absolute ethanol. The solvent in the spinning solution exchanges with the non-solvent in the coagulation bath, causing the fibers to solidify and take shape. Then, it is collected and wound by a drum-type collection device and naturally dried to obtain photochromic PHA / PLA fibers.

[0087] Place the photochromic fibers and ordinary colored yarns on a unwinding rack or a creel respectively, and control the parallel arrangement of multiple strands of fibers through a yarn guide hook and a tensioner. The tension of the photochromic fibers is 0.3 cN / dtex, and the tension of the ordinary colored yarns is 0.5 cN / dtex. Set the twist range to 1600 twists per meter and synchronously transport them to the twisting zone through a yarn guide roller. Twist the photochromic fibers (2 pieces) and the ordinary colored yarns at 500 rpm. Check whether the plied yarn after doubling is uniform to avoid uneven tightness or winding phenomena.

[0088] Effect evaluation 1

[0089] Figure 1 Among them, it is white before color change. After twisting with a dark green ordinary yarn, the ordinary and color-changing fibers can be clearly distinguished. After illumination, it can be seen that the dark green yarn mixed with the color-changing fibers shows a yellow-green camouflage color, which is significantly different from the color of the ordinary fibers above.

[0090] Figure 2 Among them, it is white before color change. After twisting with a light yellow ordinary yarn and being illuminated, it can be seen that the light yellow yarn mixed with the color-changing fibers shows a yellow-brown camouflage color, which is significantly different from the color of the unilluminated fibers above.

[0091] Obviously, the above-mentioned embodiments are only examples clearly described and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for preparing a blended yarn having photochromic properties, characterized in that: The steps include: S11: mixing an organic solvent A containing polyhydroxyalkanoate and an organic solvent B containing polylactic acid to obtain a PHA / PLA spinning solution; S12: adding one or more photochromic microcapsules prepared from different photochromic solutions to the PHA / PLA spinning solution, and mixing to obtain a spinning solution; the photochromic microcapsules are obtained by heating an aqueous solution containing a melamine formaldehyde resin prepolymer, an O / W type emulsion and a dispersant under acidic conditions; the melamine formaldehyde resin prepolymer is obtained by reacting melamine and formaldehyde at high temperature under alkaline conditions, and the O / W type emulsion is obtained by reacting a photochromic solution and an aqueous solution containing sodium dodecyl sulfate; S13: performing microfluidic spinning to obtain photochromic PHA / PLA fibers; S14: Arranging the photochromic PHA / PLA fiber and the colored yarn in parallel, then doubling and twisting them to obtain the blended yarn with photochromic properties.

2. The preparation method according to claim 1, characterized in that The organic solvent A is chloroform, and the organic solvent B is dichloromethane.

3. The preparation method according to claim 1, characterized in that: The volume ratio of the organic solvent A containing polyhydroxyalkanoate to the organic solvent B containing polylactic acid is 1:

2.

4. The preparation method according to claim 1, characterized in that: The organic solvent A containing polyhydroxyalkanoate is obtained by adding polyhydroxyalkanoate to organic solvent A, stirring at 60° C. for 6 hours, and then standing for 30 minutes; the concentration of the solute is 2wt%; the organic solvent B containing polylactic acid is obtained by adding polylactic acid to organic solvent B, stirring at room temperature for 6 hours; the concentration of the solute is 10-16wt%.

5. The preparation method according to claim 1, characterized in that: The photochromic solution is selected from a tetrachloroethylene solution of spirooxazine, a dichloromethane solution of naphthopyran, or an n-octane solution of spiropyran.

6. The preparation method according to claim 1, characterized in that: In step S13, the microfluidic spinning method is: the spinning solution is sucked into a syringe, the propulsion speed is adjusted by a syringe pump, the spinning solution enters an ethanol coagulation bath, the fiber is fixed and formed, and then collected and wound by a drum-type collection device and dried naturally.

7. The preparation method according to claim 1, characterized in that: In the step S13, the spinning speed of microfluidic spinning is 2-5 mL / min.

8. The preparation method according to claim 1, characterized in that: In the step S14, the ratio of the photochromic PHA / PLA fibers and the colored yarns arranged in parallel is 2-3:

1.

9. The preparation method according to claim 1, characterized in that: In the step S14, the twisting speed is 500-2000 rpm.

10. A blended yarn with photochromic properties prepared by the preparation method according to any one of claims 1 to 9.

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