Mildew-proof and stain-resistant thermochromic multicolor paint and preparation method thereof

Abstract

The invention discloses a mould-proof and anti-pollution thermochromic multicolor coating and a preparation method thereof, and belongs to the technical field of functional building coatings. The coating comprises a thermochromic base material, a granulation liquid and a continuous phase. The core is that the thermochromic base material contains thermochromic powder and modified expanded vermiculite, and the continuous phase contains photocatalytic nano titanium dioxide coated with silicon dioxide on the surface. Through component and structural design, a photocatalytic self-cleaning mildew-proof function and a low-cost heat storage enhanced thermochromic function are integrated into a water-in-water multicolor coating system. The photocatalytic component is mainly distributed in a continuous phase, the heat storage component is concentrated in the color point, and the photocatalytic component and the heat storage component are spatially separated and have a synergistic effect. The final coating has the capabilities of decomposing organic pollutants and inhibiting mold growth under illumination, meanwhile, the color-changing thermal response speed of color points is remarkably increased, compared with a traditional temperature-sensing color-changing colorful coating, the color-changing response time is shortened by 30% or above, and the overall raw material cost is lower.

Description

Technical Field

[0001] This invention belongs to the field of architectural coatings technology, specifically relating to a thermochromic multicolor coating with anti-mildew and anti-fouling properties and its preparation method. Background Technology

[0002] Interior wall coatings are developing towards functionality, personalization, and health. Among them, thermochromic coatings can change color in response to changes in ambient temperature, providing a dynamic and interactive decorative experience for interior spaces and meeting the market's personalized demands. However, the current development of this technology field faces significant functional limitations and application bottlenecks, specifically in the following two aspects: The first category of existing technologies focuses on achieving basic thermochromic decorative effects. This type of technology typically adds thermochromic microcapsule powder to the colored particles of water-based multicolor coatings. While its decorative effect is novel, this technology has a fundamental flaw: its formulation is entirely centered around the single aesthetic function of "color change," failing to endow the coating with any inherent, active hygiene protection properties. In practical applications, especially in high-humidity or easily polluted environments such as kitchens, bathrooms, and basements, the surface of such coatings easily absorbs grease, dust, and other stains, and its porous film structure provides a breeding ground for mold spores. Experiments show that under standard anti-mold testing conditions of 28°C and 90% relative humidity, the surface mold coverage of such ordinary thermochromic coatings can exceed 50% in just 28 days, and its stain resistance is far lower than that of coatings with self-cleaning functions. This makes its aesthetic appeal unsustainable and may cause indoor hygiene problems, severely limiting its application in more functional settings.

[0003] The second category of existing technologies (such as the solution represented by CN116694169B) focuses on improving the sensitivity of color-changing performance. This technology introduces a "color-changing enhancer" composed of expensive materials such as zirconium carbide and expandable graphite, utilizing its efficient photothermal conversion and heat conduction capabilities to significantly shorten the coating's color-changing response time. However, this solution has two prominent drawbacks: First, the high cost of its core functional materials (such as zirconium carbide) makes the final product expensive, making it unsuitable for markets requiring large-scale, economical coatings, such as interior wall decoration. Second, this technology also does not address the coating's anti-mildew and anti-fouling properties. More importantly, its technical approach involves designing a single, homogeneous continuous phase coating, completely lacking the "colored particle" decorative texture and multi-layered visual effects unique to water-based multicolor coatings, thus failing to meet the market's demand for "multicolor" and "three-dimensional" decorative effects.

[0004] In summary, existing technologies present a "fragmented" state: technologies with excellent colorful decorative effects and temperature-sensitive color-changing functions (the first type) lack necessary hygiene protection performance and rapid temperature response; while technologies that focus on improving color-changing performance (the second type) sacrifice decorative diversity and cost controllability, and also neglect anti-mildew and anti-fouling functions. Summary of the Invention

[0005] The purpose of this invention is to provide a simple and reasonably designed thermochromic multicolor coating with anti-mildew and anti-fouling properties in order to solve the above problems.

[0006] The present invention achieves the above objectives through the following technical solutions: The first aspect of the present invention provides a thermochromic multicolor coating with anti-mildew and anti-fouling properties, which is prepared from the following components in parts by weight: 50-60 parts of thermochromic base material, 20-30 parts of granulation liquid, and 10-20 parts of continuous phase. The thermochromic base material comprises the following raw materials in parts by weight: 50-60 parts deionized water, 0.3-0.7 parts dispersant, 0.8-1.3 parts cellulose, 1-3 parts thermochromic powder, 25-35 parts emulsion, 4-8 parts 10% protective colloid solution, and 2-5 parts modified expanded vermiculite. The continuous phase comprises the following raw materials in parts by weight: 10-15 parts deionized water, 75-85 parts emulsion, and 0.5-2.0 parts photocatalytic nanomaterials coated with silica.

[0007] As a further optimization of the present invention, the photocatalytic nanomaterial with silica coating is silica-coated nano-titanium dioxide, with an anatase nano-titanium dioxide core and an amorphous silica coating layer with a coating layer thickness of 2-5 nanometers.

[0008] As a further optimization of the present invention, the particle size of the nano-titanium dioxide coated with silica is 10-30 nanometers.

[0009] As a further optimization of the present invention, the modified expanded vermiculite is expanded vermiculite surface-treated with silane coupling agent KH-550, with a particle size of 5-20 micrometers and a bulk density of 100-200 kg / m³. 3 .

[0010] As a further optimization of the present invention, the emulsion in the thermochromic base material is a pure acrylic emulsion or a styrene-acrylic emulsion; the emulsion in the continuous phase is a mixture of silicone-acrylic emulsion and pure acrylic emulsion, wherein the silicone-acrylic emulsion accounts for 70%-80% of the total mass of the continuous phase emulsion.

[0011] As a further optimization of the present invention, in the thermochromic base material, the mass ratio of the modified expanded vermiculite to the thermochromic powder is (1.5-2.5):1.

[0012] As a further optimization of the present invention, the continuous phase further includes 0.2-0.5 parts of defoamer, 2.5-4.0 parts of film-forming aid, and 0.3-0.6 parts of thickener.

[0013] As a further optimization of the present invention, the granulation solution comprises the following raw materials in parts by weight: 91-95 parts of deionized water, 4-8 parts of protective colloid, and 0.1-0.2 parts of crosslinking anti-settling agent.

[0014] A second aspect of this invention provides a method for preparing a thermochromic multicolor coating with anti-mildew and anti-fouling properties, characterized by comprising the following steps: Step S1. Preparation of thermochromic base material: Mix deionized water, dispersant, cellulose, thermochromic powder, modified expanded vermiculite, emulsion and 10% protective colloid solution, and stir until uniform to obtain thermochromic base material; Step S2. Preparation of granulation solution: Mix deionized water, protective colloid and crosslinking anti-settling agent, stir to dissolve, and obtain granulation solution; Step S3. Preparation of continuous phase: Deionized water, photocatalytic nanomaterials coated with silica, and emulsion are mixed and stirred to disperse evenly to obtain a continuous phase; Step S4. Granulation and mixing: Under stirring conditions with a shear rate of 800-1200 rpm, the thermochromic base material is slowly added to the granulation liquid to form colored particles; then the continuous phase is added to the mixture containing the colored particles, and the viscosity is adjusted to obtain the thermochromic multicolor coating with anti-mildew and anti-fouling properties.

[0015] As a further optimization of the present invention, in step S3, the photocatalytic nanomaterials coated with silica are first pre-dispersed with a portion of deionized water to form a slurry, and then mixed with the remaining deionized water and emulsion.

[0016] The beneficial effects of this invention are as follows: This invention successfully integrates photocatalytic self-cleaning and mildew-proof functions with temperature-sensitive color-changing functions into a single coating, breaking through the limitation of traditional coatings having only one function, and is especially suitable for places with dual requirements for hygiene and decoration. Introducing low-cost modified expanded vermiculite as a heat storage enhancer into thermochromic base material, its porous structure can quickly respond to changes in ambient temperature and efficiently transfer heat to thermochromic powder, thus shortening the color change response time of the coating by more than 30% compared with similar thermochromic coatings without heat storage materials. Attached Figure Description

[0017] Figure 1This is a schematic flowchart of the preparation method of the thermochromic multicolor coating with anti-mildew and anti-fouling properties according to the present invention. Detailed Implementation

[0018] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0019] Example 1: Preparation of a thermochromic multicolor coating with anti-mildew and anti-fouling properties: Step 1: Raw material preparation: Thermochromic base material raw materials: Deionized water: 55 parts; Dispersant (sodium polyacrylate, such as Tego Dispers 730W): 0.5 parts; Hydroxyethyl cellulose (Ashland 250HBR): 1.0 part; Thermochromic powder (blue, color-changing temperature 31℃, Guangzhou Shengse Technology): 2.0 parts; Pure acrylic emulsion (50% solids content, such as BASF Acronal S760): 30 parts; 10% protective adhesive solution (prepared using UNQ910 protective adhesive): 6 parts; Modified expanded vermiculite: 3.0 parts (Preparation method: Soak 100-mesh expanded vermiculite in an ethanol solution of 2wt% silane coupling agent KH-550 for 1 hour, filter, and dry at 80℃ to obtain surface hydrophobically modified expanded vermiculite with a particle size of about 10-15μm).

[0020] Granulation liquid raw materials: Deionized water: 94 parts; Protective adhesive (UNQ910): 5 parts; Crosslinking anti-settling agent (UNQ636): 0.15 parts; Continuous phase feedstock: Deionized water: 12 parts; Nano-titanium dioxide with silica coating (P25 core, SiO2 coating layer thickness of about 3nm, particle size of about 25nm): 1.0 part; Silicone-acrylic emulsion (48% solids content, such as Polyacrylamide GS-668): 60 parts (75% based on a total continuous phase emulsion volume of 80 parts); Pure acrylic emulsion (reactive type, 50% solids): 20 parts (accounting for 25%); Defoamer (mineral oil-based, such as BYK-024): 0.3 parts; Film-forming aid (dodecyl alcohol ester, such as Texanol): 3.0 parts; Alkali-swellable thickener (such as TT-935): 0.4 parts; Step 2: Preparation of thermochromic base material: In a stirred tank, 55 parts deionized water, 0.5 parts dispersant, and 1.0 part hydroxyethyl cellulose were added sequentially, and the mixture was stirred at 600 rpm for 10 minutes to ensure the cellulose was fully dissolved and dispersed. Then, 2.0 parts thermochromic powder and 3.0 parts modified expanded vermiculite were added, and the stirring speed was increased to 1200 rpm, dispersing for 15 minutes to ensure the powder was fully wetted and dispersed. Subsequently, the stirring speed was adjusted to 400 rpm, and 30 parts pure acrylic emulsion and 6 parts 10% protective colloid solution were slowly added, stirring for 10 minutes until the system was homogeneous. Finally, the pH was adjusted to 8.0-8.5 with ammonia water to obtain the blue thermochromic base material.

[0021] Step 3: Preparation of granulation solution: In another container, add 94 parts of deionized water and start stirring (300 rpm). Slowly sprinkle in 5 parts of UNQ910 protective colloid powder. After adding all the powder, increase the stirring speed to 800 rpm and stir for 30 minutes until the protective colloid is completely dissolved and the solution is clear. Then add 0.15 parts of UNQ636 crosslinking anti-settling agent and continue stirring for 10 minutes to obtain the granulation solution.

[0022] Step 4: Preparation of the continuous phase: First, 1.0 part of nano-titanium dioxide with a silica coating was mixed with 5 parts of deionized water (from a total of 12 parts) and pre-dispersed at 1500 rpm for 10 minutes using a high-speed disperser to prepare a homogeneous slurry. In a stirred tank, the remaining 7 parts of deionized water, 0.3 parts of defoamer, and 3.0 parts of film-forming aid were added and stirred at 500 rpm for 5 minutes. Then, while stirring, the above nano-titanium dioxide slurry, 60 parts of silicone-acrylic emulsion, and 20 parts of pure acrylic emulsion were added sequentially and stirred for 15 minutes to ensure uniform mixing. Finally, 0.4 parts of alkali-swellable thickener were slowly added, and a small amount of water was added as needed to adjust the system viscosity to a Forte 4 cup viscosity of 90-100 seconds, resulting in a continuous phase.

[0023] Step 5: Granulation and final coating preparation: Transfer the granulation solution obtained in step three to a granulation vessel, start stirring and control the shear rate at 1000 rpm. Slowly add all the thermochromic base material obtained in step two to the granulation solution at a constant rate using a peristaltic pump, controlling the feeding time to 15-20 minutes. After feeding is complete, continue shearing at 1000 rpm for 5 minutes to form a suspension of uniformly sized blue colored particles.

[0024] While maintaining stirring (this can be reduced to 300-400 rpm), slowly add the entire continuous phase obtained in step four to the suspension containing the colored particles. After the addition is complete, continue stirring for 10 minutes to ensure the system is thoroughly mixed. The final product is a blue-toned, thermochromic multicolor coating with anti-mildew and anti-fouling properties.

[0025] Effect verification and comparison: To verify the effectiveness of this invention, the following tests were conducted: Color-change response time test: The coating prepared in this embodiment and a comparative coating (the only difference in formulation from this embodiment is that 3.0 parts of modified expanded vermiculite are not added to the thermochromic base material, otherwise they are exactly the same) were sprayed onto asbestos boards and dried to form films. The samples were rapidly moved from a 25°C environment to a 40°C constant temperature platform, and the process of the colored dots changing from the initial color to the high-temperature set color was recorded using a high-definition camera. The time required for the color to reach 90% stable change was determined using image analysis software. Test results: The color-change response time of the coating in this embodiment was 28 seconds, while that of the comparative coating was 42 seconds. The color-change response time of this embodiment was shortened by approximately 33%.

[0026] Anti-mold performance test (refer to GB / T 1741-2007): Samples coated with the paint of this embodiment and samples coated with ordinary commercially available thermochromic multicolor paint (without photocatalytic components) were placed in a mold test chamber, inoculated with a mixed spore suspension of Aspergillus niger, etc., and cultured for 28 days at a temperature of 28±1℃ and a relative humidity of >90%. The mold growth on the sample surface was observed. Results: The mold growth coverage area on the surface of the ordinary paint sample exceeded 50%, grade 3 (severe mold growth). In contrast, the sample surface of this embodiment only had sporadic mold spots at the edges, with a coverage area of ​​less than 5%, grade 0 (almost sterile).

[0027] Stain resistance (self-cleaning) test: Methylene blue solution was uniformly coated on the surfaces of two samples to simulate organic pollutants, and they were placed outdoors under natural sunlight (sunny weather, UV index > 5). The color fading was observed after 24 hours. Results: The blue residue on the surface of the sample with ordinary paint was obvious; the blue residue on the sample in this embodiment was almost completely removed, demonstrating a significant photocatalytic ability to decompose organic matter.

[0028] Cost estimation: The cost of the main functional materials in this embodiment is compared with that in the embodiment of CN116694169B in the prior art. The cost of the modified expanded vermiculite and coated nano-TiO2 added in this embodiment is much lower than that of materials such as zirconium carbide, expandable graphite, and carbon fiber in the prior art. It is estimated that, while achieving the functions of anti-mildew and anti-fouling and rapid color change, the raw material cost of this invention can be reduced by about 35-45% compared with the solution in the prior art.

[0029] Examples 2-3: Examples 2 and 3 follow the preparation method of Example 1, only adjusting the amount of key components; the specific proportions are shown in Table 1. The resulting products also possess the functions of rapid temperature-sensitive color change and mildew and stain resistance.

[0030]

[0031] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A thermochromic multicolor paint with mildew-resistant stain resistance and a preparation method, characterized in that, It is prepared from the following components by mass: thermosensitive color-changing base 50-60 parts, granulation liquid 20-30 parts, continuous phase 10-20 parts; The thermosensitive color-changing base comprises the following raw materials by weight: deionized water 50-60 parts, dispersant 0.3-0.7 parts, cellulose 0.8-1.3 parts, thermochromic powder 1-3 parts, emulsion 25-35 parts, 10% protective glue solution 4-8 parts, modified expanded vermiculite 2-5 parts; The continuous phase comprises the following raw materials by weight: deionized water 10-15 parts, emulsion 75-85 parts, photocatalytic nanomaterials coated with surface silica 0.5-2.0 parts.

2. The thermochromatic multichromatic paint with mildew resistant stain repellency according to claim 1, characterized in that: The photocatalytic nanomaterials coated with surface silica are nanometer titanium dioxide coated with surface silica, the core of the core-shell structure is anatase nanometer titanium dioxide, the shell is an amorphous silica coating layer, and the coating layer is 2-5 nanometers thick.

3. The thermochromatic multichromatic paint with mildew resistant stain repellency according to claim 1, characterized in that: The particle size of the nanometer titanium dioxide coated with surface silica is 10-30 nanometers.

4. The thermochromatic multichromatic paint with mildew resistant stain repellency according to claim 1, wherein: The modified expanded vermiculite is expanded vermiculite treated by silane coupling agent KH-550, with a particle size of 5-20 microns and a bulk density of 100-200 kg / m 3 .

5. The thermochromatic multichromatic paint with mildew resistant stain repellency according to claim 1, wherein: The emulsion in the thermosensitive color-changing base is a pure acrylic emulsion or a styrene-acrylic emulsion; the emulsion in the continuous phase is a mixture of a silicone-acrylic emulsion and a pure acrylic emulsion, wherein the silicone-acrylic emulsion accounts for 70%-80% of the total mass of the continuous phase emulsion.

6. The thermochromatic multichromatic paint with mildew resistant stain repellency according to claim 1, wherein: In the thermosensitive color-changing base, the mass ratio of the modified expanded vermiculite to the thermochromic powder is (1.5-2.5):

1.

7. The thermochromatic multichromatic paint with mildew resistant stain repellency according to claim 1, wherein: The continuous phase further comprises 0.2-0.5 parts of a defoaming agent, 2.5-4.0 parts of a film-forming aid, and 0.3-0.6 parts of a thickening agent.

8. The thermochromatic multichromatic paint with mildew resistant stain repellency according to claim 1, wherein: The granulation liquid comprises the following raw materials by weight: deionized water 91-95 parts, protective glue 4-8 parts, and cross-linking anti-settling agent 0.1-0.2 parts.

9. A process for the preparation of a thermochromic multicolour coating with mildew and stain resistance according to any one of claims 1 to 8, characterized in that, It comprises the following steps: Step S1. Preparing a thermosensitive color-changing base: mixing deionized water, dispersant, cellulose, thermochromic powder, modified expanded vermiculite, emulsion, and 10% protective glue solution, and stirring until uniform to obtain the thermosensitive color-changing base; Step S2. Preparing a granulation liquid: mixing deionized water, protective glue, and cross-linking anti-settling agent, and stirring to dissolve to obtain the granulation liquid; Step S3. Preparing a continuous phase: mixing deionized water, photocatalytic nanomaterials coated with surface silica, and emulsion, and stirring to disperse uniformly to obtain the continuous phase; Step S4. Granulation and mixing: slowly adding the thermosensitive color-changing base to the granulation liquid under stirring conditions with a shear rate of 800-1200 rpm to form colored particles; then adding the continuous phase to the mixture containing the colored particles, and adjusting the viscosity to obtain the thermosensitive color-changing multi-color coating with mildew resistance and stain resistance.

10. The method of claim 9, wherein, In step S3, the photocatalytic nanomaterials coated with surface silica are first pre-dispersed with part of the deionized water to form a slurry, and then mixed with the remaining deionized water and emulsion.

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