Degradable photochromic fabric and preparation method thereof

Abstract

The application discloses a degradable photochromic fabric and a preparation method thereof. The fabric comprises a fabric substrate containing degradable organic components, a photochromic functional layer arranged on the surface of the fabric substrate, an interface reinforcing layer between the fabric substrate and the photochromic functional layer, and a light-transmitting protective layer outside the photochromic functional layer. The photochromic functional layer comprises photochromic microcapsules and a degradable film-forming adhesive. The core material of the photochromic microcapsules is a reversible photochromic compound, and the wall material is a degradable polymer or a natural polymer material. The interface reinforcing layer and the degradable film-forming adhesive synergistically improve the bonding strength of the functional layer and the substrate. The obtained fabric has good degradability, reversible photochromic performance, washing and wear resistance, and wearing comfort, and can be applied to the fields of clothes, bags, curtains, tents, children's products, ultraviolet early warning products, environment self-adaptive camouflage materials and intelligent interactive textiles.

Description

Technical Field

[0001] This invention belongs to the field of functional textile materials technology, and relates to a functional fabric that combines environmentally friendly degradation properties with reversible photochromic properties, specifically a biodegradable photochromic fabric and its preparation method. Background Technology

[0002] With the rapid development of smart textiles, green textiles, and functional apparel, photochromic fabrics with reversible color-changing capabilities have shown broad application prospects in clothing, decoration, ultraviolet warning, camouflage protection, and interactive displays. Currently, most mainstream photochromic fabrics are based on petroleum-based textile substrates, introducing photochromic components through surface coating, printing, or blending spinning to achieve light-responsive color changes. CN104452350A uses photochromic compounds combined with melamine resin and sorbitol to create dyes, which are then applied to the fabric surface via a printing and dyeing process to form a microencapsulated color-changing layer, improving the adhesion of the color-changing components. CN105970625A uses photochromic masterbatch combined with a polyethylene substrate, coated onto the fiber surface to produce color-changing spun yarns and fabrics, improving colorfastness and thermal stability. CN202242217U coats a base fabric with a photochromic coating containing microencapsulated photosensitive powder, achieving reversible color changes while maintaining wearing comfort.

[0003] Despite breakthroughs in color-changing effects and process implementation, existing technologies still have significant shortcomings: the fabric substrates are mostly petroleum-based fibers such as polyester, nylon, and polypropylene, which are difficult to degrade naturally after use, resulting in insufficient eco-friendliness; the photochromic functional layer is mostly attached by simple coating, padding, or printing, with limited adhesion, and is prone to peeling off and failure after friction, washing, and repeated bending; traditional high-proportion resin coatings easily clog fabric pores, leading to a stiff feel and reduced breathability; the color-changing components are easily affected by oxygen, moisture, heat, and excessive ultraviolet radiation, resulting in a short reversible cycle life; and the finishing systems mostly use recalcitrant resins and non-environmentally friendly auxiliaries, making it difficult to simultaneously meet the requirements of green manufacturing and end-product biodegradability.

[0004] Furthermore, simply replacing the petroleum-based substrate in conventional photochromic fabrics with a biodegradable substrate often fails to yield products with stable performance. On one hand, biodegradable fibers such as polylactic acid, polyhydroxyalkanoates, and cellulose differ from traditional petroleum-based fibers in surface polarity, crystalline structure, hydrothermal stability, and process tolerance. Conventional high-temperature curing or strong resin finishing conditions can easily lead to a hardened feel, decreased mechanical properties, or impaired degradation performance of the substrate. On the other hand, while conventional non-degradable adhesives or simple surface coatings can achieve short-term color-changing effects, poor interfacial compatibility between the functional layer and the biodegradable substrate results in microcapsule migration, coating cracking, and functional attenuation under washing, friction, and repeated bending conditions, while also weakening the overall biodegradability of the material. Therefore, achieving high bonding strength between the functional layer and the substrate, stable cyclic color-changing, and softness and breathability while ensuring the biodegradability of the substrate is a core technical challenge that urgently needs to be addressed in this field.

[0005] Therefore, developing a biodegradable photochromic fabric that is based on biodegradable fibers, has stable color-changing properties, is washable and abrasion-resistant, comfortable and breathable, and conforms to the concept of green environmental protection has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a biodegradable photochromic fabric and its preparation method. By sequentially constructing an interface reinforcement layer, a photochromic functional layer, and a light-transmitting protective layer on the surface of the biodegradable fabric substrate, the invention solves the technical problem in the prior art that it is still difficult to balance the bonding strength of the functional layer, the stability of cyclic color change, comfort, and overall environmental friendliness by simply replacing the biodegradable substrate.

[0007] The technical concept of this invention lies in: introducing active sites on the surface of a biodegradable substrate using an interface reinforcement layer, which can undergo hydrogen bonding, electrostatic adsorption, and / or cross-linking with the adhesive and microcapsule wall material; using a biodegradable film-forming adhesive to form a continuous flexible film layer at a lower curing temperature, stably fixing the photochromic microcapsules to the substrate surface; and using a light-transmitting protective layer to inhibit the damage to the functional layer caused by oxygen, moisture, and external friction. The interface reinforcement layer, biodegradable film-forming adhesive, and light-transmitting protective layer work together to not only maintain the biodegradable properties of the material system but also improve the adhesion strength between the functional layer and the substrate, washability, abrasion resistance, and reversible color-changing cycle stability without significantly sacrificing the fabric's breathability and softness.

[0008] The method for preparing the biodegradable photochromic fabric of the present invention includes the following: Among them, the effective component types and application methods of the interface reinforcement layer, the ratio of photochromic microcapsules to biodegradable film-forming binders, the drying / fixation temperature window, and the amount of light-transmitting protective layer are key control parameters that balance bonding strength, color-changing efficiency, comfort, and degradation performance.

[0009] (1) Substrate preparation: The fabric substrate is prepared by weaving, knitting or non-woven processes using one or more of polylactic acid fiber, polyhydroxy fatty acid ester fiber, polycaprolactone fiber, polybutylene succinate fiber, cellulose fiber, lyocell fiber, viscose fiber, cotton fiber, hemp fiber, silk fibroin fiber and chitosan fiber. The biodegradable organic components in the fabric account for more than 70% of the total organic components by mass, preferably more than 80%, and more preferably more than 85%.

[0010] (2) Substrate pretreatment: The obtained fabric substrate is subjected to one or more of the following pretreatments: impurity removal, plasma treatment, alkali treatment, enzyme treatment or sizing modification, to improve the surface activity of the substrate and the adhesion of the coating.

[0011] (3) Construction of interface reinforcement layer: The pretreated fabric substrate is immersed in the interface treatment liquid, and after immersion and drying, an interface reinforcement layer is formed on the surface of the substrate; the effective components in the interface treatment liquid include one or more of tannic acid, chitosan, sodium alginate and citric acid, so as to improve the bonding strength between the fabric substrate and the photochromic functional layer.

[0012] (4) Preparation of biodegradable photochromic finishing solution: Based on solid content, 15-50 parts of photochromic microcapsules, 5-30 parts of biodegradable film-forming binder, and 0.1-8 parts of interface conditioning and dispersing agent are mixed, with water and / or biodegradable organic solvent as the balance, for a total of 100 parts. The mixture is stirred and dispersed evenly to obtain the biodegradable photochromic finishing solution. The core material of the photochromic microcapsules includes one or more reversible photochromic compounds selected from spiropyrans, spiroxazines, naphthopyrans, diarylethylenes, and azobenzenes; the wall material includes one or more biodegradable polymers or natural polymers selected from gelatin, chitosan, alginate, cellulose derivatives, polylactic acid, polycaprolactone, and starch derivatives; the biodegradable organic solvent can be selected from one or more of ethyl lactate, ethyl acetate, and dimethyl carbonate.

[0013] (5) Functional layer finishing: The photochromic finishing liquid is applied to the surface of the fabric substrate by means of padding, scraping, spraying, printing or layer-by-layer self-assembly, and then dried at 50~90℃ and fixed at 80~130℃ for 1~8min to form a photochromic functional layer; the temperature and time window is used to balance the integrity of film formation, the maintenance of microcapsule activity and the stability of biodegradable substrate.

[0014] (6) Construction of protective layer: A light-transmitting protective layer composed of polylactic acid, polycaprolactone, chitosan, cellulose derivatives or their composites is applied to the outside of the photochromic functional layer, and the amount of the protective layer is controlled to be 0.5~10 g / m. 2After being cured at a low temperature of 50~80℃ for 1~10 minutes, a biodegradable photochromic fabric is obtained; the amount of adhesion is controlled to achieve a balance between light transmittance, abrasion resistance and fabric hand feel.

[0015] The present invention has at least the following beneficial effects: (1) This invention does not achieve environmental friendliness simply by replacing the substrate with a biodegradable material. Instead, it improves the interfacial compatibility and adhesion between the functional layer and the biodegradable substrate by working together with the interface enhancement layer and the biodegradable film-forming adhesive, thereby solving the problem of easy detachment of the photochromic layer on the biodegradable substrate.

[0016] (2) The photochromic microcapsules and the light-transmitting protective layer together reduce the adverse effects of oxygen, moisture, friction and excessive ultraviolet radiation on the photochromic components, which is conducive to maintaining the reversibility and cycle stability of color change / recoloration.

[0017] (3) By controlling the ratio of microcapsules to biodegradable film-forming binder in the photochromic finishing liquid, as well as the drying and fixing temperature and the amount of protective layer attached, a stable functional layer can be formed without excessively clogging the fabric pores, taking into account softness, breathability and durability.

[0018] (4) The system of each layer of the present invention is preferably constructed using biodegradable or natural polymer materials, which is beneficial to improving the overall environmental friendliness and end-use adaptability of the materials, and is applicable to clothing, bags, tents, curtains, children's products, ultraviolet warning products and intelligent interactive textiles. Attached Figure Description

[0019] Figure 1 A schematic diagram of the structure of a biodegradable photochromic fabric; Figure 2 A schematic diagram of the preparation method for biodegradable photochromic fabric; Figure 3 A schematic diagram illustrating the color change of a biodegradable photochromic fabric before and after exposure to light. Figure 4 This diagram illustrates the performance retention of biodegradable photochromic fabrics after multiple washes / cycles of color change. Detailed Implementation

[0020] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. The purpose and effects of the present invention will become clearer. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0021] Example 1 A biodegradable photochromic fabric and its preparation method, comprising the following steps: A biodegradable photochromic fabric is composed of a polylactic acid lyocell blended knitted fabric substrate, an interface reinforcement layer, a photochromic functional layer, and a light-transmitting protective layer.

[0022] The fabric substrate is made of polylactic acid fiber and lyocell fiber in a mass ratio of 60:40, and knitted fabric is obtained through knitting process.

[0023] The interface reinforcement layer is prepared by the following process: the fabric substrate is immersed in a mixed aqueous solution of 1.0% tannic acid and 0.8% chitosan for 5 minutes, rolled with a roll-off rate of 70%, and dried at 70 degrees Celsius for 3 minutes to form the interface reinforcement layer.

[0024] The photochromic functional layer is prepared using the following process: Photochromic microcapsules use spiropyran-based photochromic compounds as the core material and gelatin-chitosan composite wall material as the wall material. Based on solid content, 30 parts of photochromic microcapsules, 12 parts of biodegradable polyester emulsion, and 1 part of dispersant, with deionized water as the balance, totaling 100 parts, are mixed evenly to prepare a photochromic finishing solution. The finishing solution is applied to the fabric surface by padding, with a padding rate of 75%. It is dried at 65°C for 4 minutes and fixed at 105°C for 3 minutes to form the photochromic functional layer.

[0025] The light-transmitting protective layer is prepared using the following process: a 1.5% (w / w) polycaprolactone dispersion is applied to the surface of the photochromic functional layer by a thin spraying method, with the adhesion amount controlled at 2 grams per square meter. The film is formed at 60 degrees Celsius to obtain a biodegradable photochromic fabric.

[0026] The fabric obtained in this embodiment can change from light color to dark purple under ultraviolet light irradiation, and can gradually return to its original color after the light is removed. The fabric has good softness and breathability.

[0027] Example 2 A biodegradable photochromic fabric, comprising a lyocell cotton woven fabric substrate and a photochromic functional layer.

[0028] The fabric substrate is made of lyocell fiber and cotton fiber through an interlacing process to produce a woven fabric.

[0029] In the photochromic functional layer, the photochromic microcapsules use naphthopyran compounds as the core material and alginate cellulose derivatives as the composite wall material; the binder adopts a polylactic acid emulsion and chitosan compound system.

[0030] A photochromic functional layer is applied to the substrate surface using a scraping coating process, and a transparent chitosan thin layer is set on the outer surface of the functional layer as a protective layer.

[0031] The resulting fabric exhibits a noticeable color change under sunlight, making it suitable for outdoor clothing and UV warning fabrics.

[0032] Example 3 A biodegradable photochromic fabric is composed of a nonwoven fabric substrate made of chitosan fiber and polyhydroxyalkanoate fiber composite and a locally patterned photochromic layer.

[0033] The fabric substrate is made from chitosan fiber and polyhydroxyalkanoate fiber, and is produced by nonwoven process to form a porous and highly flexible nonwoven fabric substrate.

[0034] The photochromic finishing solution uses spirooxazine-based photochromic microcapsules as its functional component, combined with a biodegradable film-forming binder and dispersant. Using a screen printing process, the photochromic finishing solution is printed onto the surface of a nonwoven fabric substrate according to a preset pattern. After drying and fixing, a locally patterned photochromic layer is formed.

[0035] The resulting fabric exhibits clear patterned color changes under light stimulation, with a sensitive response and obvious color changes, making it suitable for children's educational fabrics, decorative fabrics, and interactive display materials.

[0036] Comparative scale and performance characterization description The following comparative examples were set up: Comparative Example 1, no interface reinforcement layer was set, and the other conditions were the same as in Example 1; Comparative Example 2, an interface reinforcement layer was set, but the biodegradable film-forming adhesive was replaced with a conventional non-degradable film-forming resin, and the other conditions were the same as in Example 1; Comparative Example 3, no light-transmitting protective layer was set, and the other conditions were the same as in Example 1.

[0037] Comparing the peel strength, ΔE retention rate after soaping, color change retention rate after cyclic cycles, and surface cracking, powdering, and detachment of each sample, it was found that Example 1 exhibited superior cyclic stability and durability compared to Comparative Examples 1-3, with a more robust functional layer. Comparative Example 1, due to insufficient interfacial active sites or weak film-forming fixation, showed a functional layer more prone to detachment under washing, friction, and bending conditions. While Comparative Example 2 achieved some initial adhesion, its overall environmental friendliness decreased, and its compatibility with the biodegradable substrate and microcapsule wall material was poor. Comparative Example 3 was more susceptible to color change degradation due to oxygen, moisture, and external friction. It can be seen that the interfacial reinforcement layer, biodegradable film-forming adhesive, and light-transmitting protective layer in this invention have a significant impact on the bonding strength, cyclic stability, and durability of the final biodegradable photochromic fabric.

[0038] It will be understood by those skilled in the art that the above descriptions are merely preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. All modifications and equivalent substitutions made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A method for preparing a degradable photochromic fabric, characterized in that, Includes the following: Use fabric substrates containing biodegradable organic components; The obtained fabric substrate is pretreated to improve the surface activity of the substrate and the adhesion to the coating; After the treated fabric substrate is immersed in the interface treatment solution, it is rolled and dried to form an interface reinforcement layer on the surface of the substrate. Preparation of a biodegradable photochromic finishing solution; The photochromic finishing liquid is applied to the surface of the obtained fabric substrate and then dried and cured to form a photochromic functional layer. A light-transmitting protective layer slurry is applied to the outside of the photochromic functional layer, and after film formation and curing, a biodegradable photochromic fabric is obtained.

2. The method for preparing the biodegradable photochromic fabric according to claim 1, characterized in that, The fabric substrate is made of one or more of the following: polylactic acid fiber, polyhydroxyalkanoate fiber, polycaprolactone fiber, polybutylene succinate fiber, cellulose fiber, lyocell fiber, viscose fiber, cotton fiber, linen fiber, fibroin fiber, and chitosan fiber, and is produced by weaving, knitting, or non-woven processes.

3. The method for preparing the biodegradable photochromic fabric according to claim 1, characterized in that, The biodegradable organic components in the fabric substrate account for more than 70% of the total organic components by mass.

4. The method for preparing the biodegradable photochromic fabric according to claim 1, characterized in that, The pretreatment is one or more of the following: impurity removal, plasma treatment, alkali treatment, enzyme treatment, or sizing modification.

5. The method for preparing the biodegradable photochromic fabric according to claim 1, characterized in that, The effective components in the interface treatment solution include one or more of tannic acid, chitosan, sodium alginate, and citric acid.

6. The method for preparing the biodegradable photochromic fabric according to claim 1, characterized in that, The biodegradable photochromic finishing solution contains, by solid content, 15-50 parts of photochromic microcapsules, 5-30 parts of biodegradable film-forming binder, 0.1-8 parts of interface conditioning and dispersing agent, with water and / or biodegradable organic solvent as the balance, for a total of 100 parts.

7. The method for preparing the biodegradable photochromic fabric according to claim 6, characterized in that, The core material of the photochromic microcapsule comprises one or more reversible photochromic compounds selected from spiropyrans, spiroxazines, naphthopyrans, diarylethylenes, and azobenzenes; the wall material comprises one or more biodegradable polymers or natural polymers selected from gelatin, chitosan, alginate, cellulose derivatives, polylactic acid, polycaprolactone, and starch derivatives.

8. The method for preparing the biodegradable photochromic fabric according to claim 1, characterized in that, The drying temperature is 50~90℃, and the curing temperature is 80~130℃ for 1~8 minutes.

9. The method for preparing the biodegradable photochromic fabric according to claim 1, characterized in that, The transparent protective layer paste is composed of one or more of polylactic acid, polycaprolactone, chitosan, and cellulose derivatives, and the protective layer adhesion amount is 0.5-10 g / m 2 .

10. A biodegradable photochromic fabric, characterized in that, It is prepared by the preparation method described in any one of claims 1-9.

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