A photochromic microcapsule, a photochromic fiber and a method for preparing the same.

Abstract

This invention discloses a photochromic microcapsule, a photochromic fiber, and a method for preparing the same, belonging to the field of new materials technology. Using polycarbonate as the microcapsule wall material, photochromic dyes and anti-aging additives are encapsulated within the microcapsules. By optimizing the microcapsule composition, the processing resistance of the organic photochromic dyes is improved. This method differs from existing technologies for preparing photochromic fibers, which suffer from poor heat resistance, poor fatigue resistance, poor abrasion resistance, poor air permeability, and complex processes. The process is simple and easy to promote.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, specifically relating to a photochromic microcapsule, a photochromic fiber, and a method for preparing the same. Background Technology

[0002] Photochromic materials undergo reversible photochemical reactions when exposed to light of different intensities and wavelengths, making them widely used in various fields such as information storage, decoration and protection, imaging detection, and anti-counterfeiting. Among these applications, the color changes that accompany the photochemical reaction process lend novelty and dynamism to products, making them particularly popular with fashion designers.

[0003] Polyester fiber is the most widely used and consumed fiber material in the textile and apparel industry. It has high strength and elastic recovery ability, low price, and excellent mechanical properties, abrasion resistance, solvent resistance, and acid and alkali resistance, making it an ideal fabric carrier.

[0004] Most existing photochromic materials used in polyester fibers are organic spirocyclic color-changing dyes and their microcapsules. These materials have high photosensitivity and fast response speed, resulting in poor robustness. External stimuli such as light, heat, acid, oxygen, and mechanical force can all damage the dye molecular structure, causing it to lose its ability to undergo photoreversible reactions. The conventional PBT polyester spinning processing temperature is above 260℃, exceeding the tolerance range of spirocyclic dyes and also exceeding the tolerance temperature of conventional microcapsules. Furthermore, the strong shearing of the melt by the screw can severely tear the structure of the microcapsules, exposing the photochromic molecules to the harsh processing environment and causing the color-changing performance to fail.

[0005] Furthermore, since spirocyclic dyes are also a type of thermochromic material, during conventional polyester carrier processing, some spirocyclic molecules will open their rings to form a colored state. The phenolic anions in the colored state have poor oxygen resistance and are easily affected by the terminal carboxyl groups of the polyester at high temperatures and are further oxidized, thus losing their color-changing ability. At the same time, the deteriorated products are mostly brownish-yellow in color, which not only affects the color-changing performance but also contaminates the base color of the yarn. In addition, due to the high crystallinity of PBT and PET polyesters and the large number of hard chain segments, the activity space of the spiropyran cyanine ring-opening change is greatly limited, so the color-changing performance of the material cannot be fully expressed.

[0006] Currently, most conventional polyester color-changing fibers are produced using a coating printing process. Color-changing fabrics made by this method have a stiff feel, poor breathability, and weak adhesion between the color-changing layer and the polyester, making the fabric not resistant to washing and prone to peeling off during use. Under this method, the color-changing material only exists on the outermost layer of the polyester fabric, resulting in serious coating aging problems and poor color-changing performance durability.

[0007] Existing technologies have also attempted to address the aforementioned issues through various means. For example, using modified polyester with low melting point and low carboxyl content to prepare color-changing masterbatch with photochromic dyes, followed by core-sheath composite melt spinning, can significantly reduce processing temperature and decrease dye performance degradation. However, modified polyester is expensive, complex to synthesize, has poor mechanical properties and durability, and the core-sheath composite spinning process is complex. Therefore, this type of polyester yarn is usually only used for anti-counterfeiting / colorful logos, limiting its application.

[0008] For example, using inorganic color-changing units such as WO3 to construct conventional polyester color-changing fibers results in poor compatibility with polymers, requiring grafting processing, which increases the complexity and cost of the process. Furthermore, the grafting raw materials are often highly toxic. In addition, the color-changing properties of inorganic materials mostly originate from charge migration between lattice defects, making batch-to-batch quality control difficult. The colors are also limited to a single shade, far fewer than organic color-changing dyes, significantly restricting design possibilities. Moreover, WO3 requires hydrothermal synthesis, resulting in low space-time yield, unstable batch-to-batch quality, high energy consumption, and high wastewater treatment volume, which is not conducive to large-scale promotion. Summary of the Invention

[0009] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0010] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a photochromic microcapsule.

[0011] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including,

[0012] The microcapsules are obtained by emulsifying a composite oil phase and a composite aqueous phase at a volume ratio of 1:4 to 20, followed by heating and evaporation.

[0013] The composite oil phase is obtained by dissolving the core layer material and the wall layer material in an oily solvent and then mixing them; the composite aqueous phase solution is obtained by dissolving a phase stabilizer and a dispersant in water.

[0014] The core material is composed of photochromic dyes, thermal stabilizers, light stabilizers and ultraviolet absorbers, the wall material is polycarbonate, and the mass ratio of the core material to the wall material is 1:4~24.

[0015] As a preferred embodiment of the photochromic microcapsule of the present invention, the core layer material comprises, by mass parts, 50-90 parts of photochromic dye, 10-40 parts of heat stabilizer, 0-10 parts of light stabilizer and 0-10 parts of ultraviolet absorber.

[0016] As a preferred embodiment of the photochromic microcapsule of the present invention, wherein the photochromic dye is an organic photochromic dye, including one of spiropyran, spiroxazine, benzopyran, and naphthopyran;

[0017] The heat stabilizer is a composition of hindered phenolic antioxidants and phosphite antioxidants, including two or more of antioxidants 80, 168, 330, 626, 636, 686, 1010, 1790, XH-245, and THP-EPQ.

[0018] The light stabilizer includes one or more of light stabilizer 770 and light stabilizer 944;

[0019] The ultraviolet absorber includes one or more of ultraviolet absorber 326, ultraviolet absorber 329, ultraviolet absorber 360, ultraviolet absorber 460, and ultraviolet absorber 1577.

[0020] As a preferred embodiment of the photochromic microcapsules of the present invention, the oily solvent includes one or more of methyl acetate, ethyl acetate, diethyl ether, dichloromethane, chloroform, and carbon tetrachloride.

[0021] As a preferred embodiment of the photochromic microcapsule of the present invention, wherein: by mass percentage, the content of phase stabilizer in the composite aqueous phase is 0.5~2%, and the content of dispersant is 0.05~0.5%; wherein, the phase stabilizer is polyvinyl alcohol, and the dispersant includes one or more of polyoxyethylene sorbitan fatty acid ester, sorbitan fatty acid ester, sodium carboxymethyl cellulose, and hydroxyethyl cellulose.

[0022] Another object of the present invention is to provide a method for preparing photochromic microcapsules, comprising,

[0023] The core material and the wall material are dissolved in an oily solvent to obtain a core solution and a wall solution, respectively. The core solution and the wall solution are mixed at high speed to obtain a composite oil phase solution.

[0024] A phase stabilizer and a dispersant are dissolved in water and mixed to obtain a composite aqueous solution;

[0025] The composite aqueous solution and the composite oil solution are first mixed at a volume ratio of 1:1 and placed in an emulsifier and emulsified at a speed of 10,000~15,000 rpm for 3~5 minutes to obtain a pre-emulsion.

[0026] Continue adding the composite aqueous solution to the pre-emulsion until the volume ratio of the composite oil phase to the composite aqueous phase in the emulsion is 1:4~20. Emulsify for 3~5 minutes, then add sodium hydroxide to adjust the pH to 7.0~8.0 to obtain the precursor emulsion.

[0027] The precursor emulsion is stirred and heated at a speed of 500~2000 rpm and a temperature of 20~80℃. The mixture is heated and evaporated until the organic solvent escapes to obtain a dispersion. The dispersion is then separated and dried to obtain photochromic microcapsules.

[0028] Another object of the present invention is to provide a photochromic fiber, comprising, by weight parts, the following components:

[0029] 0-20 parts of the photochromic capsule as described in any one of claims 1-5, 0-2 parts of toughening agent, 0-1 part of transesterification inhibitor, 0-0.2 parts of wetting and dispersing agent, 0-0.5 parts of anti-aging agent, and 76.3-100 parts of conventional polyester.

[0030] In a preferred embodiment of the photochromic fiber described in this invention, the toughening agent is a styrene-ethylene-butene-styrene block copolymer.

[0031] The transesterification inhibitor includes one or more of sodium hexametaphosphate, sodium dihydrogen phosphate, and disodium hydrogen phosphate.

[0032] The wetting and dispersing agent includes one or more of stearic acid soap and ethylene bis-stearamide;

[0033] The anti-aging agent includes any two combinations of antioxidant 80, antioxidant 168, antioxidant 330, antioxidant 626, antioxidant 636, antioxidant 686, antioxidant 1010, antioxidant 1790, antioxidant XH-245, and antioxidant THP-EPQ.

[0034] The conventional polyester includes one or more of polyethylene terephthalate and polybutylene terephthalate, wherein polyethylene terephthalate has a melting point ≥240℃ and an intrinsic viscosity of 0.6~0.7 dL / g, and polybutylene terephthalate has a melting point ≥220℃ and an intrinsic viscosity of 0.95~1.05 dL / g.

[0035] Another object of the present invention is to provide a method for preparing photochromic fibers, comprising,

[0036] Photochromic capsules, toughening agents, transesterification inhibitors, wetting and dispersing agents, anti-aging agents, and conventional polyester are mixed evenly in a high-speed mixer and then melt-spun to obtain photochromic fibers.

[0037] As a preferred embodiment of the method for preparing the photochromic fiber described in this invention, wherein:

[0038] The high-speed mixing temperature is 50~110℃, and the high-speed mixing time is 180s~300s; the temperature of each zone of the melt spinning is 260~295℃.

[0039] Beneficial effects of this invention:

[0040] (1) The photochromic microcapsules of the present invention can encapsulate photochromic dyes, light and heat stabilizing agents in the microcapsules. When the microcapsules are damaged during the processing, they can provide protection in a more timely manner. The wall material selected for the microcapsules has high compatibility with polyester materials, has a high upper limit for addition, and has little impact on mechanical properties. Therefore, microcapsules with high wall material content can be used to better protect photochromic dyes.

[0041] (2) The alkaline environment in the process of preparing photochromic microcapsules and the presence of transesterification inhibitors in the yarn inhibit the degradation of the performance of photochromic dyes by the terminal carboxyl groups in conventional polyester. At the same time, the transesterification inhibitors reduce the crosslinking between the wall material and the polyester, and reduce the tearing of the microcapsules by the screw during spinning. As a result, the photochromic dyes are in a static thermal process during processing, thus protecting their photochromic properties.

[0042] (3) The invention optimizes the composition of microcapsules and photochromic yarns, and uses a mature microcapsule process to obtain high-performance conventional polyester photochromic fibers through melt spinning. This is different from the shortcomings of existing technologies in the preparation of photochromic fibers, such as poor color-changing performance, poor heat resistance, poor fatigue resistance, poor friction resistance, poor air permeability, and complex processes. The process is simple and easy to promote. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0044] Figure 1 The NMR spectrum of the optically variable dye synthesized in Example 1 of this invention is shown.

[0045] Figure 2 This is a thermogravimetric analysis diagram of the photochromic dye in Example 1 of the present invention.

[0046] Figure 3 This is a thermogravimetric analysis diagram of the photochromic microcapsule in Example 1 of the present invention.

[0047] Figure 4 This is a comparison image of the DTY yarn before and after color change obtained in Example 7 of the present invention.

[0048] Figure 5 This is a comparison image of the DTY yarn before and after color change obtained in Example 8 of the present invention.

[0049] Figure 6 This is a comparison image of the DTY yarn before and after color change obtained in Example 9 of the present invention. Detailed Implementation

[0050] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0051] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0052] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0053] Unless otherwise specified, all raw materials used in this invention are commercially available in the field.

[0054] Example 1

[0055] Reference Figures 1-3 This embodiment provides a method for preparing photochromic microcapsules using N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyr as an organic photochromic dye, specifically as follows:

[0056] 1) Preparation of the photochromic dye N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran (CAS No. 16111-07-2), the reaction formula is shown in Formula A:

[0057] (Formula A);

[0058] 25 mL of 2,3,3-trimethyl-3H-indole (Shanghai Maclean Biochemical Technology Co., Ltd.), 14 mL of 2-bromoethanol (Shanghai Maclean Biochemical Technology Co., Ltd.), and 15 mL of methanol were added to a 100 mL flask and stirred under reflux for 12 h. The mixture was then cooled to 4 °C, filtered, washed with cold methanol, and dried to obtain a pink intermediate 1-(2-hydroxyethyl)-2,3,3-trimethyl-3H-indole-1-bromonium, with a yield of 88%.

[0059] Take 10 g of the intermediate product, 9 g of 5-nitrosalicylic acid, and 100 mL of ethanol. Reflux under a nitrogen atmosphere for 1.5 hours, freeze to 4°C, filter, wash with cold ethanol, and dry to obtain the purple photochromic dye N-hydroxyethyl-3,3-dimethyl-6-nitroindolinespiropyran, with a yield of 61%.

[0060] The NMR spectrum of the product is as follows Figure 1 As shown, its characterization data is 1 H NMR (300 MHz, CDCl3) δ 8.03-7.99(m,2H), 7.21-7.16(m,1H), 7.11-7.08(m,1H), 6.92-6.87(m,1H), 6.77(d, J=8.4Hz,1H), 6.74(d, J=7.8Hz, 1H), 5. 88(d, J=10.5Hz, 1H), 3.83-3.68(m,2H), 3.50-3.28(m,2H), 1.28(s,3H), 1.19(s,3H).

[0061] 2) Preparation of photochromic microcapsules:

[0062] Mix 5g of photochromic dye N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran, 2g of antioxidant 1010 (RIANOX® 1010), 2g of antioxidant 626 (RIANOX® 626), 0.7g of light stabilizer 770 (Tinuvin® 770), 0.3g of UV absorber 326 (Tinuvin® 326), and 50mL of ethyl acetate to form a core layer solution.

[0063] 40g of polycarbonate (Lupoy® 1302HP-07) was dissolved in 400mL of chloroform to form a wall layer solution;

[0064] After mixing the wall layer solution and the core layer solution, stir at 500 rpm for 5 minutes until the mixture is homogeneous and transparent to obtain a composite oil phase solution;

[0065] 60g of polyvinyl alcohol (Changchun Chemical BP-17) and 12g of sodium carboxymethyl cellulose were dissolved in 6L of water and stirred until completely dissolved to obtain a composite aqueous solution.

[0066] The composite aqueous solution and the composite oil solution were first mixed at a volume ratio of 1:1 and emulsified in an emulsifier at 12000 rpm for 3 min to obtain a pre-emulsion.

[0067] Continue adding the remaining composite aqueous phase solution in two batches, repeating the emulsification process for each batch, until NaOH is added to adjust the pH to 8 to obtain the microcapsule precursor emulsion;

[0068] The precursor emulsion was heated to 65°C and maintained at a stirring rate of 500 rpm for 12 hours. The mixture was evaporated until the volume of the reaction liquid did not decrease significantly (organic solvent escaped) to obtain a dispersion. After centrifugation and drying, the dispersion yielded 10% pink photochromic microcapsules for conventional polyester fibers. The color changed from light pink to blue under light.

[0069] This embodiment uses a model spiropyran photochromic dye, which is a spirocyclic photochromic dye with a relatively simple structure and contains hydroxyl groups that can be post-modified. Figure 2 , Figure 3 The figures shown are thermogravimetric analysis (TGA) diagrams of the photochromic dye and microcapsules used in this embodiment. It can be seen that the overall static thermal stability increases by approximately 30 degrees Celsius after being made into microcapsule material. This indicates that the photochromic microcapsules prepared by this invention can encapsulate the photochromic dye, light and heat stabilizing agents within the microcapsule, providing more timely protection when the microcapsules are damaged during processing.

[0070] Example 2

[0071] This embodiment provides a method for preparing photochromic microcapsules using commercially available (colorless to yellow) photochromic dyes as the core material, specifically as follows:

[0072] 12g of photochromic dye (Narcissus Yellow, raw powder of sunlight-changing material, Tianjin Fuxin Sunshine Technology Co., Ltd.), 3.5g of antioxidant 1790 (RIANOX® 1790), 4g of antioxidant 168 (RIANOX® 168), and 0.5g of light stabilizer 944 (RIASORB®UV-944) were mixed evenly in 100ml of ethyl acetate to form the core layer solution.

[0073] 80g of polycarbonate (Lupoy® 1302HP-07) was dissolved in 800mL of dichloromethane to form a wall layer solution;

[0074] After mixing the wall layer solution and the core layer solution, stir at 500 rpm for 5 minutes until the mixture is homogeneous and transparent to obtain a composite oil phase solution;

[0075] 75g polyvinyl alcohol (Changchun Chemical BP-17) and 5g Span 60 were dissolved in 5L of water and stirred until completely dissolved to obtain a composite aqueous solution.

[0076] The composite aqueous solution and the composite oil solution were first mixed at a volume ratio of 1:1 and emulsified in an emulsifier at 12000 rpm for 3 min to obtain a pre-emulsion.

[0077] Continue adding the remaining composite aqueous phase solution in two batches, repeating the emulsification process for each batch, until NaOH is added to adjust the pH to 8 to obtain the microcapsule precursor emulsion;

[0078] The precursor emulsion was heated to 50°C and maintained at a stirring rate of 300 rpm for 12 hours. After evaporation until the volume of the reaction liquid did not decrease significantly (organic solvent escaped), a dispersion was obtained. The dispersion was centrifuged and dried to obtain white photochromic microcapsules for conventional polyester fibers with a content of 12%. The color changed from white to yellow under light.

[0079] Example 3

[0080] This embodiment provides a method for preparing photochromic microcapsules using commercially available (colorless to red) photochromic dyes as the core material, specifically as follows:

[0081] 5g of photochromic dye (carmine, sunlight-changing material raw powder, Tianjin Fuxin Sunshine Technology Co., Ltd.), 2g of antioxidant 330 (RIANOX® 330), 2g of antioxidant 686 (RIANOX® 686), 0.7g of light stabilizer 770 (Tinuvin® 770), and 0.3g of UV absorber 329 (Tinuvin® 329) were mixed evenly in 200ml of ethyl acetate to form the core layer solution.

[0082] 40g of polycarbonate (Lupoy® 1302HP-07) was dissolved in 400mL of dichloromethane to form a wall layer solution;

[0083] After mixing the wall layer solution and the core layer solution, stir at 500 rpm for 5 minutes until the mixture is homogeneous and transparent to obtain a composite oil phase solution;

[0084] 90g of polyvinyl alcohol (Changchun Chemical BP-17) and 6g of Tween 20 were dissolved in 6L of water and stirred until completely dissolved to obtain a composite aqueous solution.

[0085] The composite aqueous solution and the composite oil solution were first mixed at a volume ratio of 1:1 and emulsified in an emulsifier at 12000 rpm for 3 min to obtain a pre-emulsion.

[0086] Continue adding the remaining composite aqueous phase solution in two batches, repeating the emulsification process for each batch, until NaOH is added to adjust the pH to 8 to obtain the microcapsule precursor emulsion;

[0087] The precursor emulsion was heated to 50°C and maintained at a stirring rate of 300 rpm for 12 hours. After evaporation until the volume of the reaction liquid did not decrease significantly (organic solvent escaped), a dispersion was obtained. The dispersion was centrifuged and dried to obtain 10% white photochromic microcapsules for conventional polyester fibers. The color changed from white to red under light.

[0088] Example 4

[0089] This embodiment provides a method for preparing photochromic microcapsules using commercially available (colorless to green) photochromic dyes as the core material, specifically as follows:

[0090] 8g of photochromic dye (Ink Green, raw powder of sunlight-changing material, Tianjin Fuxin Sunshine Technology Co., Ltd.), 1g of antioxidant XH-245 (Irganox® 245), and 1g of antioxidant 686 (RIANOX® 686) were mixed evenly in 200ml of ethyl acetate to form the core layer solution.

[0091] 40g of polycarbonate (Lupoy® 1302HP-07) was dissolved in 400mL of chloroform to form a wall layer solution;

[0092] After mixing the wall layer solution and the core layer solution, stir at 500 rpm for 5 minutes until the mixture is homogeneous and transparent to obtain a composite oil phase solution;

[0093] 80g of polyvinyl alcohol (Changchun Chemical BP-17) and 8g of Tween 40 were dissolved in 8L of water and stirred until completely dissolved to obtain a composite aqueous solution.

[0094] The composite aqueous solution and the composite oil solution were first mixed at a volume ratio of 1:1 and emulsified in an emulsifier at 12000 rpm for 3 min to obtain a pre-emulsion.

[0095] Continue adding the remaining composite aqueous phase solution in two batches, repeating the emulsification process for each batch, until NaOH is added to adjust the pH to 8 to obtain the microcapsule precursor emulsion;

[0096] The microcapsule precursor emulsion was heated to 65°C and maintained at a stirring rate of 1000 rpm for more than 12 hours. After evaporation until the volume of the reaction liquid did not decrease significantly (organic solvent escaped), a dispersion was obtained. After centrifugation and drying, a 16% light green photochromic microcapsule for conventional polyester fibers was obtained. The color changed from light green to dark green under light.

[0097] The particle size distribution of the microcapsules obtained before centrifugation and drying in Examples 1-4 was tested using an MS3000 particle size analyzer. The results are shown in Table 1.

[0098] Table 1. Composition and particle size distribution of different microcapsules

[0099]

[0100] As can be seen from Table 1, the particle size of the microcapsules prepared by the method of the present invention is not much different from that of traditional microcapsules, and is smaller than the diameter of common spinning fineness specifications of single filaments, indicating that it has high spinnability.

[0101] Example 5

[0102] This embodiment provides a method for preparing color-changing fibers using photochromic microcapsules from Example 1 as raw materials, specifically as follows:

[0103] 93.4 parts of polybutylene terephthalate powder (Yizheng Chemical Fiber GX112), 5 parts of photochromic microcapsules prepared in Example 1, 1 part of styrene-ethylene-butene-styrene block copolymer (TSR SEBS 6151), 0.3 parts of sodium hexametaphosphate, 0.1 parts of ethylene bis-stearamide, 0.1 parts of antioxidant 1010, and 0.1 parts of antioxidant 626 were mixed in a high-speed mixer at 60°C for 180s to obtain a spinning material.

[0104] The above materials were placed in a single-screw melt spinning machine, with spinning temperatures of 260℃, 265℃, 270℃, 270℃, 270℃, 270℃, 270℃, and 270℃ in each zone. The melt was extruded through the spinneret, cooled by air, oiled, and wound. The spinning specification was 150d / 48f, and the winding speed was 2800r / min, yielding POY yarn.

[0105] The obtained POY yarn was false-twisted to obtain white to blue photochromic polyester (PBT) DTY fiber, with a false twisting D / Y ratio of 1.68.

[0106] Example 6

[0107] The difference between this embodiment and Example 5 is that the polybutylene terephthalate powder (Yizheng Chemical Fiber GX112) is replaced with polyethylene terephthalate powder (Yizheng Chemical Fiber FC510), and the spinning temperatures of each zone are adjusted to 280℃, 285℃, 290℃, 290℃, 290℃, 290℃, and 290℃ respectively. The rest of the preparation process is the same as in Example 5, and the color-changing fiber of this embodiment is obtained.

[0108] Example 7

[0109] This embodiment provides a method for preparing color-changing fibers using photochromic microcapsules from Example 2 as raw materials, specifically as follows:

[0110] 94.2 parts of polybutylene terephthalate powder (Yizheng Chemical Fiber GX112), 5 parts of photochromic microcapsules from Example 2, 1 part of styrene-ethylene-butene-styrene block copolymer (TSR SEBS 6151), 0.3 parts of sodium hexametaphosphate, 0.1 parts of ethylene bis-stearamide, 0.1 parts of antioxidant 1010, and 0.1 parts of antioxidant 626 were mixed in a high-speed mixer at 60°C for 180 seconds to obtain a spinning material.

[0111] The above materials were placed in a single-screw melt spinning machine, with spinning temperatures of 280℃, 285℃, 290℃, 290℃, 290℃, 290℃, and 290℃ in each zone. The melt was extruded through the spinneret, cooled by air, oiled, and wound. The spinning specification was 150d / 48f, and the winding speed was 2800r / min, yielding POY yarn.

[0112] The obtained POY yarn was false-twisted to produce white-to-yellow photochromic polyester (PBT) DTY fiber. The D / Y ratio of the false twister was 1.68. The comparison images of the fiber before and after color change are shown below. Figure 4 As shown (colorless to yellow).

[0113] Example 8

[0114] This embodiment provides a method for preparing color-changing fibers using photochromic microcapsules from Example 3 as raw materials, specifically as follows:

[0115] 93.4 parts of polyethylene terephthalate powder (Yizheng Chemical Fiber FC510), 5 parts of photochromic microcapsules from Example 3, 1 part of styrene-ethylene-butene-styrene block copolymer (TSR SEBS 6151), 0.3 parts of sodium hexametaphosphate, 0.1 parts of ethylene bis-stearamide, 0.1 parts of antioxidant 1010, and 0.1 parts of antioxidant 626 were mixed in a high-speed mixer at 60°C for at least 180 seconds to obtain a spinning material.

[0116] The above materials were placed in a single-screw melt spinning machine, with spinning temperatures of 280℃, 285℃, 290℃, 290℃, 290℃, 290℃, and 290℃ in each zone. The melt was extruded through the spinneret, cooled by air, oiled, and wound. The spinning specification was 150d / 48f, and the winding speed was 2800r / min, yielding POY yarn.

[0117] The obtained POY yarn was false-twisted to produce white-to-red discoloration polyester (PET) DTY fibers. The D / Y ratio of the false twister was 1.68. The comparison images of the fibers before and after discoloration are shown below. Figure 5 As shown (from colorless to red).

[0118] Example 9

[0119] This embodiment provides a method for preparing color-changing fibers using photochromic microcapsules from Example 4 as raw materials, specifically as follows:

[0120] 95.3 parts of polyethylene terephthalate powder (Yizheng Chemical Fiber FC510), 3.1 parts of the light green to dark green microcapsules obtained in Example 3, 1 part of styrene-ethylene-butene-styrene block copolymer (TSR SEBS 6151), 0.3 parts of sodium hexametaphosphate, 0.1 parts of ethylene bis-stearamide, 0.1 parts of antioxidant 1010, and 0.1 parts of antioxidant 626 were mixed in a high-speed mixer at 60°C for at least 180 seconds to obtain a spinning material.

[0121] The above materials were placed in a single-screw melt spinning machine, with spinning temperatures of 280℃, 285℃, 290℃, 290℃, 290℃, 290℃, and 290℃ in each zone. The melt was extruded through the spinneret, cooled by air, oiled, and wound. The spinning specification was 150d / 48f, and the winding speed was 2800r / min, yielding POY yarn.

[0122] The obtained POY yarn was false-twisted to produce white-to-green discoloration polyester (PET) DTY fibers. The D / Y ratio of the false twister was 1.68. The comparison images of the fibers before and after the discoloration are shown below. Figure 5 As shown (colorless to green).

[0123] Comparative Example 1

[0124] The difference between this comparative example and Example 5 is that photochromic microcapsules are not prepared; instead, the raw material is directly spun into yarn. Specifically:

[0125] 93.4 parts of polybutylene terephthalate powder (Yizheng Chemical Fiber GX112), 0.5 parts of N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran, 4 parts of polycarbonate, 1 part of styrene-ethylene-butene-styrene block copolymer (TSR SEBS 6151), 0.3 parts of sodium hexametaphosphate, 0.1 parts of ethylene bis-stearamide, 0.3 parts of antioxidant 1010, 0.3 parts of antioxidant 626, 0.07 parts of light stabilizer 770, and 0.03 parts of UV absorber 326 were mixed in a high-speed mixer at 60°C for at least 180 seconds to obtain the spinning material.

[0126] The above materials were placed in a single-screw melt spinning machine with spinning temperatures of 260℃, 265℃, 270℃, 270℃, 270℃, 270℃, and 270℃ in each zone. The melt was extruded through the spinneret, cooled by air, oiled, and wound. The spinning specification was 150d / 48f, and the winding speed was 2800r / min, resulting in brownish-yellow POY yarn that does not have color-changing properties.

[0127] Comparative Example 2

[0128] The difference between this comparative example and Example 6 is that photochromic microcapsules are not prepared; the raw material is spun directly. Specifically:

[0129] 93.4 parts of polyethylene terephthalate powder (Yizheng Chemical Fiber FC510), 0.5 parts of N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran, 4 parts of polycarbonate, 1 part of styrene-ethylene-butene-styrene block copolymer (TSR SEBS 6151), 0.3 parts of sodium hexametaphosphate, 0.1 parts of ethylene bis-stearamide, 0.3 parts of antioxidant 1010, 0.3 parts of antioxidant 626, 0.07 parts of light stabilizer 770, and 0.03 parts of UV absorber 326 were mixed in a high-speed mixer at 60°C for at least 180 seconds to obtain the spinning material.

[0130] The above materials were placed in a single-screw melt spinning machine with spinning temperatures of 280℃, 285℃, 290℃, 290℃, 290℃, 290℃, and 290℃ in each zone. The melt was extruded through the spinneret, cooled by air, oiled, and wound. The spinning specification was 150d / 48f, and the winding speed was 2800r / min, resulting in brown POY yarn that does not have color-changing properties.

[0131] The DTY yarn samples spun in Examples 5-9 and Comparative Examples 1 and 2 were placed on an X-rite Ci7800 colorimeter for testing. After being exposed to sunlight for 1 minute until the color no longer changed significantly, the color was measured again. The color was rated according to the built-in color-changing chart of Datacolor. The results are shown in Table 2.

[0132] Table 2. Color change of different photochromic polyester DTY yarns after 1 minute in midday sunlight.

[0133]

[0134] As shown in Table 2, the color difference values ​​of the conventional polyester yarns constructed in Examples 5 and 7-9 before and after color change are all >25, indicating significant color changes. The response rate fully meets the requirements for conventional textile use. However, the model dye used in Example 5 has a low static thermal stability temperature and an initial decomposition temperature of 215°C. After being encapsulated in microcapsules, the initial decomposition temperature is approximately 248°C. Therefore, when using a PET carrier with a higher spinning temperature, the performance of the yarn sample will further decline. In other words, the color-changing effect of Example 6 is significantly inferior to that of Example 5. Furthermore, in Comparative Examples 1-2, it can be seen that direct spinning under the same composition results in significant degradation of the photochromic dye, with the yarn sample turning significantly yellow and dark. This further illustrates that by optimizing the composition of the microcapsule wall material and simultaneously encapsulating the auxiliaries within the microcapsules, this method can effectively protect the photochromic dye and reduce the degradation of photochromic dyes with poor thermal stability during polyester spinning.

[0135] The DTY yarn samples spun in Examples 5-9 and Comparative Examples 1 and 2 were placed on a single yarn strength tester for testing. The fiber strength results are shown in Table 3.

[0136] Table 3 Mechanical properties of different photochromic polyester DTY yarns

[0137]

[0138] As can be seen from the data in Table 3, the main component of the optically variable fiber prepared by the method of the present invention is still conventional polyester. Since polycarbonate has high compatibility with conventional polyester and its proportion in the fiber is not high, it has little impact on the mechanical strength of the material. Therefore, the mechanical properties of the optically variable yarn prepared by this method are comparable to those of conventional polyester yarn, which fully meets the requirements of the subsequent weaving process. The strength of the same composition in Comparative Examples 1-2 further illustrates the rationality of the selection of microcapsule wall material in this method.

[0139] Example 10

[0140] The difference between this embodiment and embodiment 7 is that the content of photochromic dye in the photochromic microcapsules is adjusted to 5%, the amount of microcapsules added during spinning is 12 parts, and the amount of PET (polybutylene terephthalate powder) added is reduced accordingly, so as to obtain the photochromic microcapsules and photochromic fibers of this embodiment.

[0141] Example 11

[0142] The difference between this embodiment and embodiment 7 is that the amount of Span 60 added during the preparation of the photochromic capsules is adjusted to 30g, while the other process parameters are the same as in embodiment 7, resulting in the photochromic microcapsules and photochromic fibers of this embodiment.

[0143] Comparative Example 4

[0144] The difference between this comparative example and Example 7 is that no heat stabilizer was added during the preparation of the photochromic capsules, and the corresponding amount of heat stabilizer was added during spinning. All other process parameters were the same as in Example 7, and photochromic microcapsules and photochromic fibers of this example were obtained respectively.

[0145] Comparative Example 5

[0146] The difference between this comparative example and Example 7 is that no dispersing agent is added during the preparation of the photochromic capsules. All other process parameters are the same as in Example 7, resulting in the photochromic microcapsules and photochromic fibers of this example.

[0147] Comparative Example 6

[0148] The difference between this comparative example and Example 7 is that no phase stabilizer is added during the preparation of the photochromic capsules. All other process parameters are the same as in Example 7, resulting in the photochromic microcapsules and photochromic fibers of this example.

[0149] Comparative Example 7

[0150] The difference between this comparative example and Example 7 is that NaOH was not added to adjust the pH of the solution during the preparation of the photochromic capsules. All other process parameters were the same as in Example 7, resulting in the photochromic microcapsules and photochromic fibers of this example.

[0151] The particle size distribution, fiber color change, and mechanical properties of the photochromic microcapsules prepared in Examples 10 and 11 and Comparative Examples 4 to 7 were determined according to the aforementioned method and compared with those in Example 7. The results are shown in Table 4.

[0152] Table 4

[0153]

[0154] As can be seen from Table 4, in the microcapsule preparation process of the present invention, when the heat stabilizer is changed to be added during spinning, the filament sample is darker before the color change. If the dispersant and phase stabilizer are not added, the microcapsule particle size is too large, the component pressure rises severely, the slurry drips severely, and spinning is impossible. In contrast, the spinning condition of Comparative Example 7, which did not add NaOH to provide alkaline conditions, was poor and there was slurry dripping.

[0155] The photochromic microcapsules prepared in this invention encapsulate photochromic dyes and light and heat stabilizing agents within the microcapsules, providing more timely protection when the microcapsules are damaged during processing. The wall material selected for the microcapsules has high compatibility with polyester materials, exhibiting a high upper limit for addition without significantly reducing mechanical properties. Therefore, microcapsules with high wall material content can be used to better protect the photochromic dyes. The alkaline preparation conditions and the presence of transesterification inhibitors in the yarn inhibit the performance degradation of photochromic dyes by the terminal carboxyl groups in conventional polyester. Simultaneously, the spinnability of the microcapsules is ensured to a certain extent. The transesterification inhibitors reduce cross-linking between the wall material and polyester, reducing the tearing of the microcapsules by the screw during spinning, thus keeping the photochromic dye in a static thermal state during processing, thereby protecting its photochromic properties.

[0156] In summary, this invention optimizes the composition of microcapsules and photochromic yarns, and uses a mature microcapsule process to obtain high-performance conventional polyester photochromic fibers through melt spinning. This is different from the shortcomings of existing technologies in preparing photochromic fibers, such as poor color-changing performance, poor heat resistance, poor fatigue resistance, poor abrasion resistance, poor air permeability, and complex processes. The process is simple and easy to promote.

[0157] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. Photochromic microcapsules, characterized in that: The microcapsules are obtained by emulsifying a composite oil phase and a composite aqueous phase at a volume ratio of 1:4 to 20, followed by heating and evaporation. The composite oil phase is obtained by dissolving the core layer material and the wall layer material in an oily solvent and then mixing them; the composite aqueous phase solution is obtained by dissolving a phase stabilizer and a dispersant in water. The core material is composed of photochromic dyes, thermal stabilizers, light stabilizers and ultraviolet absorbers, the wall material is polycarbonate, and the mass ratio of the core material to the wall material is 1:4~24.

2. The photochromic microcapsule of claim 1, wherein: The core material comprises, by weight, 50-90 parts of photochromic dye, 10-40 parts of heat stabilizer, 0-10 parts of light stabilizer and 0-10 parts of ultraviolet absorber.

3. The photochromic microcapsule of claim 2, wherein: The photochromic dye is an organic photochromic dye, including one of spiropyran, spiroxazine, benzopyran, and naphthopyran; The heat stabilizer is a composition of hindered phenolic antioxidants and phosphite antioxidants, including two or more of antioxidants 80, 168, 330, 626, 636, 686, 1010, 1790, XH-245, and THP-EPQ. The light stabilizer includes one or more of light stabilizer 770 and light stabilizer 944; The ultraviolet absorber includes one or more of ultraviolet absorber 326, ultraviolet absorber 329, ultraviolet absorber 360, ultraviolet absorber 460, and ultraviolet absorber 1577.

4. The photochromic microcapsule of claim 1, wherein: The oily solvent includes one or more of methyl acetate, ethyl acetate, diethyl ether, dichloromethane, chloroform, and carbon tetrachloride.

5. The photochromic microcapsule of claim 1, wherein: The composite aqueous phase contains 0.5-2% phase stabilizer and 0.05-0.5% dispersant by mass percentage; wherein the phase stabilizer is polyvinyl alcohol and the dispersant includes one or more of polyoxyethylene sorbitan fatty acid ester, sorbitan fatty acid ester, sodium carboxymethyl cellulose, and hydroxyethyl cellulose.

6. The method for preparing photochromic microcapsules according to any one of claims 1 to 5, characterized in that: include, The core material and the wall material are dissolved in an oily solvent to obtain a core solution and a wall solution, respectively. The core solution and the wall solution are mixed at high speed to obtain a composite oil phase solution. A phase stabilizer and a dispersant are dissolved in water and mixed to obtain a composite aqueous solution; The composite aqueous solution and the composite oil solution are first mixed at a volume ratio of 1:1 and placed in an emulsifier and emulsified at a speed of 10,000~15,000 rpm for 3~5 minutes to obtain a pre-emulsion. Continue adding the composite aqueous solution to the pre-emulsion until the volume ratio of the composite oil phase to the composite aqueous phase in the emulsion is 1:4~20. Emulsify for 3~5 minutes, then add sodium hydroxide to adjust the pH to 7.0~8.0 to obtain the precursor emulsion. The precursor emulsion is stirred and heated at a speed of 500~2000 rpm and a temperature of 20~80℃. The mixture is heated and evaporated until the organic solvent escapes to obtain a dispersion. The dispersion is then separated and dried to obtain photochromic microcapsules.

7. A photochromic fiber characterized by: By weight, including, 0~20 parts of the photochromic capsule according to any one of claims 1~5, wherein the photochromic capsule is not 0 parts, 0~2 parts of a toughening agent, 0~1 parts of an ester exchange inhibitor, 0~0.2 parts of a wet dispersing agent, 0~0.5 parts of an anti-aging agent, and 76.3~100 parts of a conventional polyester.

8. The photochromic fiber of claim 7, wherein: The toughening agent is a styrene-ethylene-butylene-styrene block copolymer, The ester exchange inhibitor includes one or more of sodium hexametaphosphate, sodium dihydrogen phosphate, and disodium hydrogen phosphate; The wet dispersing agent includes one or more of stearic acid soap and ethylene bis-stearamide; The anti-aging agent includes any two of a combination of antioxidant 80, antioxidant 168, antioxidant 330, antioxidant 626, antioxidant 636, antioxidant 686, antioxidant 1010, antioxidant 1790, antioxidant XH-245, and antioxidant THP-EPQ; The conventional polyester includes one or more of polyethylene terephthalate and polybutylene terephthalate, wherein the polyethylene terephthalate has a melting point ≥ 240℃ and an intrinsic viscosity of 0.6~0.7 dL / g, and the polybutylene terephthalate has a melting point ≥ 220℃ and an intrinsic viscosity of 0.95~1.05 dL / g.

9. The method for preparing a photochromic fiber according to claim 7 or 8, characterized in that: including, The photochromic capsule, the toughening agent, the ester exchange inhibitor, the wet dispersing agent, the anti-aging agent, and the conventional polyester are mixed uniformly by a high-speed mixer, and then melt-spun to obtain a photochromic fiber.

10. The method of claim 9, wherein the photochromic fiber is prepared by: The temperature of the high-speed mixing is 50~110℃, and the time of the high-speed mixing is 180s~300s; and the temperature of each zone of the melt spinning is 260~295℃.

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