Microencapsulated thermochromic floor

Abstract

The invention relates to a microencapsulated thermochromic material. The microencapsulated thermochromic material comprises an inner core and a shell coating the inner core, the shell is prepared from melamine formaldehyde resin and anti-ultraviolet composite particles according to the volume ratio of (70 to 60) to (30 to 40); the inner core is a mixture of an electron transfer type organic compound and an inorganic phase change reinforcing agent, and the inorganic phase change reinforcing agent is composed of TiO2 loaded with 5-15 wt% of AgI nanoparticles; the anti-ultraviolet composite particles are formed by grafting silane coupling agent modified nano zinc oxide and a benzotriazole ultraviolet absorbent. The invention further relates to a color-changing floor prepared from the microencapsulated thermochromic material, and the color-changing floor is good in weather resistance and high in heat stability and temperature sensitivity.

Description

Technical Field

[0001] This invention relates to a microencapsulated thermochromic flooring. Background Technology

[0002] Color-changing flooring is a smart building material that achieves surface color changes through materials science. Its color-changing mechanism primarily relies on external environmental stimuli (such as temperature, light, or viewing angle) to trigger a physical or chemical response within the material. Depending on the stimulus source, it can be categorized into thermochromic (temperature response), photochromic (light response), and viewing angle-dependent color-changing (observation angle response). Color-changing flooring has been applied in numerous fields, including home furnishings, construction, and security.

[0003] Currently, color-changing flooring technology is limited by inherent material defects, such as poor weather resistance, which makes it prone to fading or failure under long-term ultraviolet radiation; weak thermal stability, which is not conducive to high-temperature processing; and low temperature sensitivity. Summary of the Invention

[0004] The purpose of this invention is to provide a microencapsulated thermochromic flooring with good weather resistance, high thermal stability, and high temperature sensitivity.

[0005] The present invention adopts the following technical solution: A microencapsulated thermochromic material includes a core and a shell encapsulating the core; the shell is composed of melamine-formaldehyde resin and UV-resistant composite particles in a volume ratio of 70-60:30-40; the core is a mixture of an electron-transfer type organic compound and an inorganic phase change enhancer, wherein the inorganic phase change enhancer is composed of TiO2 nanoparticles loaded with 5-15 wt% AgI; the UV-resistant composite particles are formed by grafting silane coupling agent-modified nano-zinc oxide with benzotriazole UV absorbers.

[0006] Furthermore, the core comprises 0.5-1.5 parts by weight of fluorane dye, 1.0-2.0 parts by weight of bisphenol A, 2.0-4.0 parts by weight of alcohol solvent, and 0.6-0.9 parts by weight of TiO2-loaded nanoparticles containing 5-15 wt% AgI.

[0007] Furthermore, the fluorane dyes include crystal violet lactone, 2-phenylamino-3-methyl-6-diethylaminofluorane, and fluorane black dye.

[0008] Furthermore, the alcohol solvent includes 1-tetradecyl alcohol and myristol.

[0009] Furthermore, the UV-resistant composite particles comprise 1-3 parts by weight of nano zinc oxide, 2-2.5 parts by weight of benzotriazole UV absorber, and 1-2 parts by weight of silane coupling agent.

[0010] Furthermore, the UV-resistant composite particles are prepared by the following method: i) Disperse nano-zinc oxide in an ethanol / water mixture and sonicate it; ii) Add silane coupling agent, adjust pH to 8.8~9.2, and stir at 70℃ for 3 hours to obtain modified zinc oxide; iii) The modified zinc oxide obtained in step ii) by centrifugation is washed three times with ethanol; iv) Add the modified zinc oxide and benzotriazole UV absorber treated in step iii) to toluene and then to the reaction vessel, and heat to 80°C under nitrogen protection; v) Add the initiator dropwise, react for 4 hours, and then cool to room temperature; vi) Filter and dry to obtain UV-resistant composite particles.

[0011] Furthermore, the microencapsulated thermochromic material is prepared by the following method: (1) Obtaining UV-resistant composite particles; (2) Preparation of kernel emulsion: i) Fluorane dyes, bisphenol A, alcohol solvent, and TiO2-loaded AgI nanoparticles are melt-mixed at 60-65°C; ii) Add surfactant, homogenize and emulsify to form an O / W emulsion; iii) Control the emulsion particle size to 4.5~5.5μm; (3) In-situ polymerization and coating i) Mix melamine-formaldehyde prepolymer with deionized water and adjust the pH to 4.3-4.7; ii) Add the UV-resistant composite particles slowly in 5 batches, with a 2-minute interval between each batch, and stir at 40~45℃ for 30 minutes; iii) Add the core emulsion dropwise, maintaining the temperature at 45~50℃; iv) Increase the temperature to 60~65℃ at a rate of 1℃ / min and maintain the temperature for 2 hours; v) Adjust the pH to 9.0 to terminate the reaction, and cool to 25°C; to obtain the microencapsulated thermochromic material; (4) Post-processing i) Separate the microcapsules by vacuum filtration and wash with deionized water until neutral; ii) Dry under vacuum at 40℃ for 12 hours, and collect 4~6μm particles by sieving.

[0012] A color-changing flooring comprising the aforementioned microencapsulated thermochromic material.

[0013] Furthermore, the color-changing floor includes a substrate and a microencapsulated thermochromic material dispersed in the substrate.

[0014] Furthermore, in the color-changing flooring, the substrate includes PVC plasticizer, polyurethane prepolymer, or modified rubber.

[0015] An application of the aforementioned color-changing floor in the visualization of basketball hotspot areas or in interactive art installations in gyms.

[0016] The beneficial effects of this invention are as follows: This invention adopts a strawberry-type composite microcapsule structure, and uses covalent bonds to fix the anti-ultraviolet composite particles in the melamine-formaldehyde resin shell to form a double ultraviolet barrier. After 1000 hours of QUV accelerated aging, the color change retention rate is >85%, which effectively solves the problem of photodecomposition of organic dyes.

[0017] This invention introduces AgI / TiO2 inorganic phase change enhancer, which reduces the thermochromic response error to within ±0.5℃, significantly improving the accuracy of hotspot display on sports fields.

[0018] This invention employs three different preparation processes tailored to different flooring materials, effectively expanding the applicability of microencapsulated thermochromic materials.

[0019] This solution focuses on precise response, long-lasting weather resistance, wide applicability to various processes, and economic and environmental benefits, breaking through the technical bottlenecks of existing color-changing flooring and providing reliable solutions for scenarios such as sports venues and smart homes. Detailed Implementation

[0020] The technical solution of the present invention will be described in detail below using specific embodiments.

[0021] Example 1: PVC-based basketball court flooring (color change at 45℃) 1. Preparation of microencapsulated thermochromic materials (a) Synthesis of UV-resistant composite particles i) Disperse 2 kg of nano zinc oxide in 60 kg of ethanol / water mixture (volume ratio 3:1) and sonicate for 30 minutes (power 300W). ii) Add 1.5 kg of KH-570 silane coupling agent, adjust the pH to 9.0, and stir at 70°C for 3 hours to obtain modified zinc oxide; iii) The modified zinc oxide obtained in step ii) was centrifuged (8000 rpm, 10 minutes) and washed three times with ethanol; iv) Add the modified zinc oxide treated in step iii) and 2.2 kg of UV-329 to toluene and then to the reaction vessel, and heat to 80°C under nitrogen protection; v) Add AIBN initiator (0.2 kg azobisisobutyronitrile, dissolved in 5 ml toluene), react for 4 hours, and then cool to room temperature; vi) Filter and dry to obtain ZnO / UV-329 anti-ultraviolet composite particles (grafting rate ≥92%).

[0022] (b) Core emulsion preparation i) Melt-mix 1.0 kg of crystal violet lactone, 1.5 kg of bisphenol A, 3.5 kg of 1-tetradecyl alcohol (Tm=45℃) and 0.8 kg of AgI / TiO2 (AgI loading 10wt%, particle size 180~220nm) at 65℃; ii) Add 2% SDS aqueous solution and homogenize and emulsify at high speed (15000 rpm, 5 minutes) to form an O / W emulsion; iii) Control the emulsion particle size: 4.5~5.5μm (monitored by Malvern particle size analyzer).

[0023] (c) In-situ polymerization coating i) Mix 100 kg of melamine-formaldehyde prepolymer (40% solid content) with 50 kg of deionized water and adjust the pH to 4.5; ii) Add 73 kg of UV-resistant composite particles slowly in 5 batches (2 minutes apart) and stir at 40°C for 30 minutes; iii) Slowly add the core emulsion (dropping rate 2 ml / min) while maintaining the temperature at 45°C; iv) Increase the temperature to 65°C at a rate of 1°C / min and maintain the temperature for 2 hours; v) Adjust the pH to 9.0 with 10% NaOH solution to terminate the reaction, and cool to 25°C.

[0024] (d) Post-processing i) Separate the microcapsules by vacuum filtration and wash with deionized water until neutral; ii) Dry under vacuum at 40℃ for 12 hours, and collect 4~6μm particles by sieving.

[0025] 2. Preparation method of PVC-based basketball court flooring 100 kg of PVC resin, 40 kg of DOP plasticizer, and 20 kg of calcium carbonate were mixed at 120°C for 10 minutes. The mixed material was then transferred to a two-roll mill with a 2 mm gap between the rolls. The material was cooled to 75°C using cooling water. 5 kg of microencapsulated thermochromic material was then evenly sprinkled in, and the mixture was passed through thin passes at 0.5 mm, 1 mm, and 2 mm thicknesses twice. Finally, the mixture was calendered at 105°C to obtain a 2 mm thick PVC color-changing floor.

[0026] Example 2: Polyurethane-coated flooring (color change at 31°C) 1. Preparation of microencapsulated thermochromic materials (a) Synthesis of UV-resistant composite particles i) Disperse 2 kg of nano zinc oxide in 60 kg of ethanol / water mixture (volume ratio 3:1) and sonicate for 30 minutes (power 300W). ii) Add 1.5 kg of KH-570 silane coupling agent, adjust the pH to 9.0, and stir at 70°C for 3 hours to obtain modified zinc oxide; iii) The modified zinc oxide obtained in step ii) was centrifuged (8000 rpm, 10 minutes) and washed three times with ethanol; iv) Add the modified zinc oxide treated in step iii) and 2.2 kg of UV-329 to toluene and then to the reaction vessel, and heat to 80°C under nitrogen protection; v) Add AIBN initiator (0.2 kg azobisisobutyronitrile, dissolved in 5 ml toluene), react for 4 hours, and then cool to room temperature; vi) Filter and dry to obtain ZnO / UV-329 anti-ultraviolet composite particles (grafting rate ≥92%).

[0027] (b) Core emulsion preparation i) 0.8 kg of 2-phenylamino-3-methyl-6-diethylaminofluorane, 1.2 kg of bisphenol A, 3.0 kg of myristol (Tm=31℃) and 0.6 kg of AgI / TiO2 (AgI loading 8wt%, particle size 170~190nm) are melt-mixed at 60℃; ii) Add 3% Tween-80 aqueous solution and homogenize and emulsify at high speed (17000 rpm, 8 minutes) to form an O / W emulsion; iii) Control the emulsion particle size: 3.6~4.0μm (monitored by Malvern particle size analyzer).

[0028] (c) In-situ polymerization coating i) Mix 100 kg of melamine-formaldehyde prepolymer (40% solid content) with 50 kg of deionized water and adjust the pH to 4.5; ii) Add 60 kg of UV-resistant composite particles slowly in 5 batches (2 minutes apart), and stir at 45°C for 30 minutes; iii) Slowly add the core emulsion (dropping rate 1.5 ml / min) while maintaining the temperature at 50°C; iv) Increase the temperature to 60°C at a rate of 1°C / min and maintain the temperature for 3 hours; v) Adjust the pH to 9.0 with 10% NaOH solution to terminate the reaction, and cool to 25°C.

[0029] (d) Post-processing i) Separate the microcapsules by vacuum filtration and wash with deionized water until neutral; ii) Dry under vacuum at 40℃ for 12 hours, and collect 4~6μm particles by sieving.

[0030] 2. Preparation of coating slurry Mix 100 kg of HDI polyurethane prepolymer (NCO%=8.2), 15 kg of microencapsulated thermochromic material, 5 kg of nano-alumina (30 nm), 25 kg of ethylene glycol ethyl ether acetate, and 0.2 kg of organic bismuth catalyst evenly.

[0031] 3. Preparation of polyurethane surface-coated flooring (a) Pretreatment of the substrate: Sanding of 8mm thick polyurethane elastic substrate (200 mesh). (b) Spray the coating paste onto the pretreated substrate, with a wet film thickness of 210~230μm; (c) Let stand in a constant humidity environment at 25℃ for 15 minutes; (d) Step curing: 1 hour at 40℃; 2 hours at 60℃; 1 hour at 80℃. The polyurethane surface-coated flooring is then obtained.

[0032] Example 3: SBS / EPDM rubber flooring (color development at 45℃ friction hotspot) 1. Preparation of microencapsulated thermochromic materials (a) Synthesis of UV-resistant composite particles i) Disperse 2 kg of nano zinc oxide in 60 kg of ethanol / water mixture (volume ratio 3:1) and sonicate for 30 minutes (power 300W). ii) Add 1.5 kg of KH-570 silane coupling agent, adjust the pH to 9.0, and stir at 70°C for 3 hours to obtain modified zinc oxide; iii) The modified zinc oxide obtained in step ii) was centrifuged (8000 rpm, 10 minutes) and washed three times with ethanol; iv) Add the modified zinc oxide treated in step iii) and 2.2 kg of UV-329 to toluene and then to the reaction vessel, and heat to 80°C under nitrogen protection; v) Add AIBN initiator (0.2 kg azobisisobutyronitrile, dissolved in 5 ml toluene), react for 4 hours, and then cool to room temperature; vi) Filter and dry to obtain ZnO / UV-329 anti-ultraviolet composite particles (grafting rate ≥92%).

[0033] (b) Core emulsion preparation i) 1.2 kg of fluorane black dye (CI Solvent Black 27), 1.8 kg of bisphenol A, 3.5 kg of 1-undecyl alcohol (Tm=45℃), and 0.9 kg of AgI / TiO2 (AgI loading 12wt%, particle size 200~240nm) are melt-mixed at 60℃; ii) Add 3% Tween-80 aqueous solution and homogenize and emulsify at high speed (17000 rpm, 6 minutes) to form an O / W emulsion; iii) Control the emulsion particle size: 3.6~4.0μm (monitored by Malvern particle size analyzer).

[0034] (c) In-situ polymerization coating i) Mix 100 kg of melamine-formaldehyde prepolymer (40% solid content) with 50 kg of deionized water and adjust the pH to 4.2; ii) Add 47 kg of UV-resistant composite particles slowly in 5 batches (2 minutes apart) and stir at 40°C for 30 minutes; iii) Slowly add the core emulsion (dropping rate 1.8 ml / min) while maintaining the temperature at 50°C; iv) Increase the temperature to 60°C at a rate of 1°C / min and maintain the temperature for 3 hours; v) Adjust the pH to 9.0 with 10% NaOH solution to terminate the reaction, and cool to 25°C.

[0035] (d) Surface treatment i) Separate the microcapsules by vacuum filtration and spray them with a 0.5wt% fluorosilane ethanol solution; ii) Curing with hot air at 110℃ for 30 minutes.

[0036] (e) Post-processing i) Wash with deionized water until neutral; ii) Vacuum dry at 40℃ for 12h, then sieve (2500 mesh) to obtain 5~7μm particles.

[0037] 2. Preparation of SBS / EPDM Rubber Flooring 70 kg of SBS (YH-791) and 30 kg of EPDM (4045) were added to 12 kg of naphthenic oil and mixed at 60°C for 3 minutes. 15 kg of carbon black (N550) and 3 kg of zinc oxide were added and mixed at 80°C for 8 minutes. The rubber compound was then cooled to 58°C, and 6 kg of microcapsules and 2.5 kg of DCP vulcanizing agent were added in 6 batches (45 seconds apart). Vulcanization was carried out at 135°C and 12 MPa for 10 minutes. After demolding, the mixture was cold-pressed for shaping.

[0038] Comparative Example 1 1. Preparation of microencapsulated thermochromic materials (a) Preparation of kernel emulsion i) Melt-mix 1.0 kg of crystal violet lactone, 1.5 kg of bisphenol A, 3.5 kg of 1-tetradecyl alcohol (Tm=45℃) and 0.8 kg of AgI / TiO2 (AgI loading 10wt%, particle size 180~220nm) at 65℃; ii) Add 2% SDS aqueous solution and homogenize and emulsify at high speed (15000 rpm, 5 minutes) to form an O / W emulsion; iii) Control the emulsion particle size: 4.5~5.5μm (monitored by Malvern particle size analyzer).

[0039] (b) In-situ polymerization coating i) Mix 100 kg of melamine-formaldehyde prepolymer (40% solid content) with 50 kg of deionized water and adjust the pH to 4.5; ii) Slowly add the core emulsion (dropping rate 2 ml / min) while maintaining the temperature at 45°C; iii) Increase the temperature to 65°C at a rate of 1°C / min and maintain the temperature for 2 hours; iv) Adjust the pH to 9.0 with 10% NaOH solution to terminate the reaction, and cool to 25°C.

[0040] (d) Post-processing i) Separate the microcapsules by vacuum filtration and wash with deionized water until neutral; ii) Dry under vacuum at 40℃ for 12 hours, and collect 4~6μm particles by sieving.

[0041] 2. Preparation method of PVC-based basketball court flooring 100 kg of PVC resin, 40 kg of DOP plasticizer, and 20 kg of calcium carbonate were mixed at 120°C for 10 minutes. The mixed material was then transferred to a two-roll mill with a 2 mm gap between the rolls. The material was cooled to 75°C using cooling water. 5 kg of microencapsulated thermochromic material was then evenly sprinkled in, and the mixture was passed through thin passes at 0.5 mm, 1 mm, and 2 mm thicknesses twice. Finally, the mixture was calendered at 105°C to obtain a 2 mm thick PVC color-changing floor.

[0042] Comparative Example 2 1. Preparation of microencapsulated thermochromic materials Same as Example 3.

[0043] 2. Preparation of SBS / EPDM Rubber Flooring 70 kg of SBS (YH-791) and 30 kg of EPDM (4045) were added to 12 kg of naphthenic oil and mixed at 60°C for 3 minutes. 15 kg of carbon black (N550) and 3 kg of zinc oxide were added and mixed at 150°C for 8 minutes. The rubber compound was then cooled to 58°C, and 6 kg of microcapsules and 2.5 kg of DCP vulcanizing agent were added in 6 batches (45 seconds apart). Vulcanization was carried out at 160°C and 12 MPa for 10 minutes. After demolding, the mixture was cold-pressed for shaping.

[0044] Example of effect The flooring products prepared in Examples 1-3 and Comparative Examples 1-2 were tested. Temperature response was tested according to ISO 7724, weather resistance according to ASTM G154, and mechanical properties according to ISO 37. The results are shown in Table 1.

[0045] Table 1 Performance Test Comparison Results .

Claims

1. A microencapsulated thermochromic material, characterized in that, It includes a core and a shell covering the core; the shell is composed of melamine-formaldehyde resin and anti-UV composite particles in a volume ratio of 70~60:30~40; the core is a mixture of electron transfer type organic compound and inorganic phase change enhancer, the inorganic phase change enhancer is composed of TiO2 nanoparticles loaded with 5~15wt% AgI; the anti-UV composite particles are formed by grafting silane coupling agent modified nano zinc oxide with benzotriazole UV absorbers.

2. The microencapsulated thermochromic material according to claim 1, characterized in that, The core comprises 0.5-1.5 parts by weight of fluorane dye, 1.0-2.0 parts by weight of bisphenol A, 2.0-4.0 parts by weight of alcohol solvent, and 0.6-0.9 parts by weight of TiO2-loaded nanoparticles containing 5-15 wt% AgI.

3. The microencapsulated thermochromic material according to claim 2, characterized in that, The UV-resistant composite particles comprise 1-3 parts by weight of nano zinc oxide, 2-2.5 parts by weight of benzotriazole UV absorber, and 1-2 parts by weight of silane coupling agent.

4. The microencapsulated thermochromic material according to claim 3, characterized in that, The UV-resistant composite particles are prepared by the following method: i) Disperse nano-zinc oxide in an ethanol / water mixture and treat with ultrasound; ii) Add silane coupling agent, adjust pH to 8.8~9.2, and stir at 70℃ for 3 hours to obtain modified zinc oxide; iii) The modified zinc oxide obtained in step ii) by centrifugation is washed three times with ethanol; iv) Add the modified zinc oxide and benzotriazole UV absorber treated in step iii) to toluene and then to the reaction vessel, and heat to 80°C under nitrogen protection; v) Add the initiator dropwise, react for 4 hours, and then cool to room temperature; vi) Filter and dry to obtain UV-resistant composite particles.

5. The microencapsulated thermochromic material according to claim 4, characterized in that, It is prepared by the following method: (1) Obtaining UV-resistant composite particles; (2) Preparation of kernel emulsion: i) Fluorane dyes, bisphenol A, alcohol solvent, and TiO2-loaded AgI nanoparticles are melt-mixed at 60-65°C; ii) Add surfactant, homogenize and emulsify to form an O / W emulsion; iii) Control the emulsion particle size to 4.5~5.5μm; (3) In-situ polymerization and coating i) Mix melamine-formaldehyde prepolymer with deionized water and adjust the pH to 4.3-4.7; ii) Add the UV-resistant composite particles slowly in 5 batches, with a 2-minute interval between each batch, and stir at 40~45℃ for 30 minutes; iii) Add the core emulsion dropwise, maintaining the temperature at 45~50℃; iv) Increase the temperature to 60~65℃ at a rate of 1℃ / min and maintain the temperature for 2 hours; v) Adjust the pH to 9.0 to terminate the reaction, and cool to 25°C; to obtain the microencapsulated thermochromic material; (4) Post-processing i) Separate the microcapsules by vacuum filtration and wash with deionized water until neutral; ii) Dry under vacuum at 40℃ for 12 hours, and collect 4~6μm particles by sieving.

6. A color-changing floor, characterized in that, It includes the microencapsulated thermochromic material as described in any one of claims 1 to 5.

7. The color-changing flooring according to claim 6, characterized in that, It includes a substrate and microencapsulated thermochromic materials dispersed in the substrate.

8. The color-changing flooring according to claim 7, characterized in that, The substrate includes PVC plasticizer, polyurethane prepolymer, or modified rubber.

9. The application of a color-changing floor as described in claims 6-8 in a basketball hotspot visualization or a gym interactive art installation.