Coating with optical permeability and preparation method thereof

Abstract

The invention provides a coating with optical permeability and a preparation method thereof. The coating with optical permeability is prepared from the following raw materials in parts by mass: 25 parts of water-based acrylate copolymer emulsion, 25 to 35 parts of water, 0.8 to 1.5 parts of transparent functional particles, 16 to 20 parts of functional modified inorganic filler, 5.5 to 7.5 parts of boric acid ester-silanol-hydroxyl three-function cross-linked gel precursor solution, 0.2 to 0.5 part of thickening agent, 0.2 to 0.4 part of defoaming agent, 0.5 to 1 part of dispersing agent and 0.1 to 0.3 part of preservative. 0.2 to 0.5 part of an organic amine alcohol compound; the transparent functional particles comprise at least one of glass sand and cross-linked polymethyl methacrylate microspheres; the functional modified inorganic filler comprises at least one of amino silane modified snowflake white quartz sand and amino silane modified calcined sand white marble. The coating with optical permeability is suitable for the field of indoor and outdoor decoration.

Description

Technical Field

[0001] This application relates to the field of stone-like paint coating technology, specifically to an optically transparent coating and its preparation method. Background Technology

[0002] As faux stone paint coatings with crystal clarity, three-dimensional texture and luxurious luster gain market favor, the market demand for faux stone paint coatings that can form a coating with the visual effect of natural platinum crystal luxury stone is growing.

[0003] Existing stone-like paints mostly use inorganic mineral fillers and traditional emulsion composite systems. Although they can simulate natural stone in terms of color and texture, they still have the following shortcomings in terms of optical transparency, crystal appearance, and gloss: Low light transmittance: In traditional stone-like paint coatings, the filler particle size is large and the refractive index is mismatched, which causes strong scattering of light in the coating and low light transmittance, making it difficult to present the transparent feel of platinum crystal luxury stone. High haze: Although some imitation stone paint coatings have a certain degree of transparency, the uneven internal structure or filler agglomeration leads to visual blurring and a lack of clarity and layering. Low gloss: Existing stone-like paint coatings suffer from a combination of factors, such as large filler particle size, uneven filler distribution, mismatch between the refractive index of the matrix emulsion and the filler, high surface roughness, and poor filler dispersion. This results in enhanced light scattering and uneven interface reflection after the coating is formed, making it difficult to achieve the synergistic effect of specular reflection and diffuse reflection that natural platinum crystal luxury stone possesses. Therefore, there is an urgent need to develop a coating with high light transmittance, low haze, and high gloss, which can effectively simulate the texture of high-end natural platinum crystal luxury stone and meet the application requirements of interior and exterior decoration. Summary of the Invention

[0004] This invention provides an optically transparent coating and its preparation method.

[0005] In a first aspect, this application provides an optically transparent coating, comprising, by weight parts, the following raw materials: The composition includes: 25 parts waterborne acrylate copolymer emulsion, 25-35 parts water, 0.8-1.5 parts transparent functional particles, 16-20 parts functional modified inorganic filler, 5.5-7.5 parts borate ester-silicone-hydroxyl trifunctional crosslinking gel precursor, 0.2-0.5 parts thickener, 0.2-0.4 parts defoamer, 0.5-1 part dispersant, 0.1-0.3 parts preservative, and 0.2-0.5 parts organic amine alcohols. The transparent functional particles include at least one of glass sand and cross-linked polymethyl methacrylate microspheres; the functional modified inorganic fillers include at least one of aminosilane modified snowflake white quartz sand and aminosilane modified calcined white marble.

[0006] Through the above embodiments, transparent functional particles and functional modified inorganic fillers are introduced into the film-forming matrix of the waterborne acrylate copolymer emulsion, and the gaps between the transparent functional particles and functional modified inorganic fillers are filled with borate ester-silanol-hydroxyl trifunctional crosslinking gel precursor liquid, which helps the final coating of the optically transparent coating to have optical characteristics of high light transmittance, low haze and high gloss. The glass sand and cross-linked polymethyl methacrylate microspheres in the transparent functional particles have similar refractive indices to the film-forming matrix, which can reduce Mie scattering and decrease absorption in the visible light region, thereby improving light transmittance and reducing haze. The two particles have round morphology and low surface roughness, which can make them more uniform in the coating, enhance the specular reflection of the coating, improve gloss and reduce haze. Aminosilane-modified snowflake white quartz sand and aminosilane-modified calcined white marble sand among functional modified inorganic fillers improve their wettability and stable dispersion in the water-based acrylic copolymer emulsion film-forming matrix by using amino functional groups on the surface, reducing the agglomeration and refractive index unevenness of functional modified inorganic fillers, thereby broadening the angle range of specular reflection suppression and improving gloss. The borate-silanol-hydroxyl trifunctional crosslinking gel precursor liquid forms multi-point hydrogen bond coordination with the amino groups of functional modified inorganic fillers and the carboxyl and hydroxyl groups in the waterborne acrylate copolymer emulsion film-forming matrix through its borate, silanol, and hydroxyl groups. This effectively fills the micro-gaps inside the coating, improves interfacial compatibility, and reduces the scattering intensity of light propagating in the coating due to possible voids, thereby increasing the overall light transmittance and reducing haze of the coating. At the same time, the interfacial densification and leveling improvement effects of the hydrogen bond network make the coating surface smoother and improve gloss. In summary, this application achieves the matching and construction of the refractive index of the filler and the film-forming matrix, as well as the effective filling of micro gaps, by synergistically introducing transparent functional particles, functional modified inorganic fillers, and borate ester-silanol-hydroxyl trifunctional crosslinking gel precursor liquid into the waterborne acrylate copolymer emulsion film-forming matrix. This significantly improves the light transmittance of the coating, reduces haze, and enhances gloss in terms of optical performance.

[0007] In some embodiments, the cross-linked polymethyl methacrylate microspheres include the following preparation steps: M1: Methyl methacrylate, dispersant, and initiator are dissolved in a low alcohol aqueous solution to homopolymerize methyl methacrylate free radicals into monodisperse polymethyl methacrylate seed microspheres, thus obtaining a dispersion polymerization reaction system; M2: Mix the dispersion polymerization reaction system and the crosslinking agent to allow the crosslinking agent to polymerize and form a crosslinked network structure with the polymethyl methacrylate seed microspheres to obtain crosslinked polymethyl methacrylate microspheres; The dispersant is polyvinylpyrrolidone; the lower alcohol includes at least one of ethanol and isopropanol; the initiator includes at least one of azobisisobutyronitrile and benzoyl peroxide; and the crosslinking agent includes at least one of ethylene glycol dimethacrylate and trimethylolpropane triacrylate.

[0008] Through the above implementation method, cross-linked polymethyl methacrylate microspheres are prepared in situ using a two-stage dispersion polymerization method. Step M1 constructs monodisperse polymethyl methacrylate seed microspheres, which can effectively avoid enhanced Mie scattering and local refractive index fluctuations caused by particle size mismatch. Furthermore, due to the high refractive index matching between the microspheres and the aqueous acrylate copolymer emulsion film-forming matrix, low-loss direct light transmission and uniform forward scattering are achieved in the visible light region. Step M2 introduces a cross-linking agent to construct a dense three-dimensional cross-linked network on the polymethyl methacrylate seed microspheres. Through a controllable programmed reaction, the defects of aggregation and irregular agglomeration that are prone to occur in traditional polymerization are avoided.

[0009] Furthermore, the cross-linked polymethyl methacrylate microspheres include the following preparation steps: M1: Dissolve 100 parts of methyl methacrylate, 10-15 parts of dispersant, and 1.8-3.2 parts of initiator in 1000-2500 parts of a 30%-70% (v / v) aqueous solution of lower alcohol, and stir at 100-150 rpm for 1-3 hours at 65-75°C to obtain a dispersion polymerization reaction system. M2: Mix the dispersion polymerization reaction system with 0.5-3 parts of crosslinking agent, and stir at 65-75℃ at a rate of 100-150 rpm for 8-10 hours to obtain crosslinked polymethyl methacrylate microspheres.

[0010] Through the above implementation methods, step M1 can effectively control the critical chain length and nucleation rate of methyl methacrylate in a low-alcohol aqueous solution, thereby reducing the particle size distribution range of the monodisperse polymethyl methacrylate seed microspheres. The lower stirring rate and initiator ratio ensure the rheological stability and nucleation consistency of the reaction system. In step M2, by controlling the amount of crosslinking agent and the reaction time, a denser and more uniform three-dimensional crosslinked network is formed inside the monodisperse polymethyl methacrylate seed microspheres, thereby improving the stability of the obtained crosslinked polymethyl methacrylate microspheres.

[0011] In some embodiments, the borate ester-silanol-hydroxyl trifunctional crosslinked gel precursor solution includes the following preparation steps: A functional polymer thickener, borax, and silanol compounds are mixed with water. Boric acid generated from the hydrolysis of borax undergoes borate esterification with the hydroxyl groups of the functional polymer thickener, and the silanol groups of the silanol compounds condense with the hydroxyl groups on the borax or the functional polymer thickener to obtain a borate ester-silanol-hydroxyl trifunctional crosslinked gel precursor solution. The functional polymer thickener includes at least one of polyvinyl alcohol, guar gum, hydroxypropyl methylcellulose, and hydroxyethyl cellulose; the silanol compound includes at least one of propyltrimethoxysilane and ethyltrimethoxysilane.

[0012] Through the above implementation methods, the functional polymer thickener provides abundant hydroxyl sites, which can complex and crosslink with the boric acid groups in the borax hydrolysis products, and at the same time participate in the condensation reaction of silanol compounds, forming a crosslinking network with Si-O-Si and BOC bonds as the main components, which has certain reversibility and flexible adjustment capabilities, reducing the occurrence of phase separation or pore defects, thereby forming a more transparent and dense polymer skeleton. The borate ester-silanol-hydroxyl trifunctional crosslinking gel precursor liquid exhibits a certain degree of reversibility, while the siloxane bonds provide high stability. The combination of these two properties gives the coating both the mechanical strength resulting from high crosslinking density and a certain degree of flexibility. It can construct a relatively transparent and dense polymer framework in optically transparent coatings, improving film density and mechanical strength. Furthermore, its polymer framework can effectively encapsulate and disperse functional inorganic fillers, inhibiting aggregation and sedimentation, and enhancing the storage stability and application uniformity of optically transparent coatings. The siloxane structure endows the borate ester-silanol-hydroxyl trifunctional crosslinking gel precursor liquid with excellent heat resistance and moisture resistance, while the reversible nature of the borate ester bonds endows the coating with a certain degree of self-healing ability.

[0013] Furthermore, the borate ester-silanol-hydroxyl trifunctional crosslinked gel precursor solution includes the following preparation steps: Mix 8 parts of functional polymer thickener, 1-2 parts of borax, 0.5-2 parts of silanol compound with 65-70 parts of water, and stir at 300-600 rpm for 30-60 min at 40-60℃ to obtain borate ester-silanol-hydroxyl trifunctional crosslinked gel precursor solution.

[0014] Through the above embodiments, a synergistic pre-crosslinking reaction of functional polymer thickeners, borax, and silanol compounds can be achieved under appropriate conditions to obtain a relatively uniform and fluid borate ester-silanol-hydroxyl trifunctional crosslinked gel precursor. During the reaction, the functional polymer thickener provides abundant hydroxyl sites, which undergo complexation and crosslinking with the borate groups generated by the hydrolysis of borax to form a reversible borate ester bond network. At the same time, the silanol compounds are stably hydrolyzed and condensed in water to form siloxane bonds, which can further enhance the compactness and hydrothermal stability of the obtained borate ester-silanol-hydroxyl trifunctional crosslinked gel precursor network.

[0015] In some embodiments, the aminosilane-modified snowflake white quartz sand includes the following preparation steps: Snowflake white quartz sand, aminosilane coupling agent, and hydrochloric acid solution are dispersed in an ethanol aqueous solution. The silanol groups generated by the hydrolysis of the silane coupling agent undergo a condensation reaction with the hydroxyl groups formed on the surface of the snowflake white quartz sand under acidic conditions to obtain aminosilane modified snowflake white quartz sand. The aminosilane coupling agent includes at least one of γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0016] Through the above embodiments, the aminosilane coupling agent undergoes hydrolysis and condensation under acidic conditions to form stable Si-O-Si bonds on the surface of snowflake white quartz sand and introduces amino functional groups, enabling it to undergo hydrogen bonding or ionic association with polar groups such as carboxyl and hydroxyl groups in the film-forming matrix, thereby improving wettability and dispersion stability; making its distribution in the coating more uniform, enhancing specular reflection, and improving gloss.

[0017] Furthermore, the aminosilane-modified snowflake white quartz sand comprises the following preparation steps: 100 parts of snowflake white quartz sand, 2-4 parts of silane coupling agent, and 150 parts of 0.02-0.05 mol / L hydrochloric acid solution are dispersed in 400 parts of 30%-50% ethanol aqueous solution. The mixture is stirred at 400-500 rpm for 3-5 hours at 30-40℃ to obtain aminosilane modified snowflake white quartz sand.

[0018] Through the above implementation methods, the modified layer can be made of moderate thickness and more uniformly distributed, avoiding local over-polymerization or surface defects, and making the interfacial compatibility and dispersion stability of aminosilane modified snowflake white quartz sand and waterborne acrylate copolymer emulsion matrix better.

[0019] In some embodiments, the aminosilane-modified calcined white marble includes the following preparation steps: Calcined sand white marble, silane coupling agent, and hydrochloric acid solution are dispersed in an ethanol aqueous solution. The silanol groups generated by the hydrolysis of the silane coupling agent undergo a condensation reaction with the hydroxyl groups formed on the surface of the calcined sand white marble under acidic conditions to obtain aminosilane modified calcined sand white marble. The aminosilane coupling agent includes at least one of γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0020] Through the above embodiments, the silane coupling agent undergoes hydrolysis in an ethanol aqueous solution under acidic conditions to generate a reactive silanol intermediate, which then undergoes a condensation reaction with the hydroxyl groups formed on the surface of calcined white marble under acidic conditions to form a dense and uniform silane-modified layer. The residual silanol sites on the surface of the aminosilane-modified calcined white marble and the introduction of functional groups such as amino or methacryloyl groups can enable appropriate hydrogen bonding coordination between the silanol in the aqueous acrylate copolymer emulsion and the borosilicate-silanol-hydroxyl trifunctional crosslinking gel precursor liquid, ensuring a more uniform distribution in the optically transparent coating and improving the overall light transmittance and optical uniformity of the coating.

[0021] Furthermore, the aminosilane-modified calcined white marble includes the following preparation steps: 100 parts of calcined white marble, 2-4 parts of silane coupling agent, and 150 parts of 0.02-0.05 mol / L hydrochloric acid solution were dispersed in 400 parts of 30%-50% ethanol aqueous solution. The mixture was stirred at 400-500 rpm for 3-5 hours at 30-40℃ to obtain aminosilane-modified calcined white marble.

[0022] Through the above implementation methods, controlling the volume fraction of ethanol and acidic conditions ensures the complete hydrolysis of the silane coupling agent to generate a reactive silanol intermediate, while also inhibiting its self-condensation tendency and improving the directional condensation efficiency with the hydroxyl groups on the surface of calcined white marble. Controlling the reaction temperature provides suitable activation energy for the hydrolysis and condensation reactions, while avoiding degradation or side reactions of the coupling agent caused by high temperatures. Controlling the stirring rate and reaction time promotes the formation of a relatively dense and continuous aminosilane-modified coating layer on the surface of calcined white marble.

[0023] In some embodiments, the transparent functional particles comprise glass sand and cross-linked polymethyl methacrylate microspheres; wherein the mass ratio of the glass sand to the cross-linked polymethyl methacrylate microspheres is 65:(30-40).

[0024] Through the above implementation methods, transparent functional particles are compounded at a mass ratio of glass sand to cross-linked polymethyl methacrylate microspheres of 65:(30-40), achieving a synergistic effect on high light transmittance, low haze, and high gloss of the coating. Glass sand, as a dense inorganic phase, has a refractive index similar to that of the aqueous acrylic copolymer emulsion film-forming matrix. Its rounded morphology and low surface roughness together construct stable direct light transmission channels and enhance specular reflection components, thus improving the coating's gloss. The cross-linked polymethyl methacrylate microspheres are relatively uniformly cross-linked organic transparent microspheres. Their narrow particle size distribution and surface hydroxyl groups enable them to form relatively uniform, low-intensity flexible scattering within the coating. The center establishes multi-point hydrogen bond associations with the film-forming matrix and the borate-silanol-hydroxyl trifunctional crosslinked gel precursor, effectively inhibiting aggregation and local refractive index unevenness, reducing haze and maintaining high transmittance. The above ratio achieves a triple coupling of "direct light transmission - flexible scattering - interface densification". Glass sand provides the advantages of a hard optical framework and surface leveling, while crosslinked polymethyl methacrylate microspheres compensate for multi-angle transmission and interface homogenization effects. The two form a synergistic closed loop of refractive index matching and scattering intensity regulation at the optical path and interface level, avoiding the performance bias of a single particle system, and ultimately achieving a comprehensive improvement in transmittance, haze and gloss.

[0025] In some embodiments, the functional modified inorganic filler includes aminosilane-modified snowflake white quartz sand and aminosilane-modified calcined white marble sand; wherein the mass ratio of the aminosilane-modified snowflake white quartz sand and the aminosilane-modified calcined white marble sand is 80:(15-25).

[0026] Through the above implementation method, the functional modified inorganic filler is a compound of aminosilane-modified snowflake white quartz sand and aminosilane-modified calcined white marble sand at a mass ratio of 80:(15-25), which shows a synergistic gain on the optical performance of the coating. The core snowflake white quartz sand of aminosilane-modified snowflake white quartz sand is mainly composed of SiO2; the core calcined white marble sand of aminosilane-modified white marble sand is mainly composed of CaCO3. When the two are compounded in a specific ratio, the high light transmittance and low scattering characteristics of SiO2 and the gloss enhancement effect of CaCO3 complement each other. The aminosilane-modified snowflake white quartz sand dominates the light transmittance and optical uniformity of the coating, while the aminosilane-modified calcined white marble sand provides additional gains in terms of surface reflection and leveling. The two form a synergistic effect in terms of refractive index transition and interface densification layer, which avoids the performance bias that may occur in a single filler system and achieves a comprehensive improvement in light transmittance, haze and gloss.

[0027] In some embodiments, the aqueous acrylate copolymer emulsion is Acronal® S 790; the thickener includes at least one of polyvinyl alcohol, hydroxypropyl methylcellulose, and hydroxyethyl cellulose; the defoamer includes at least one of polyether-modified trisiloxane, polyoxypropylene ethylene glycerol ether, and silicone oil; the dispersant includes at least one of sodium polyacrylate, lauryl ether-4 phosphate, and dihydroxyethyl tallow amine; the preservative includes at least one of sodium benzoate and phenoxyethanol; and the organic amine alcohol compound includes at least one of triethanolamine, 2-amino-2-methyl-1-propanol, and N-methyldiethanolamine.

[0028] Through the above embodiments, Acronal® S 790 waterborne acrylic copolymer emulsion, as a styrene-acrylate copolymer dispersion, exhibits excellent pigment binding strength and filler compatibility. As an optically transparent coating, it forms a dense and mechanically strong transparent skeleton structure after film formation. This transparent skeleton structure demonstrates outstanding alkali resistance and water resistance, ensuring the stability and durability of the coating during long-term use. The dispersant reduces the agglomeration tendency of transparent functional particles and functionally modified inorganic fillers. The defoamer rapidly breaks down microbubbles during the film formation process of the optically transparent coating, inhibiting the formation of residual bubbles. Light scattering interference; thickeners help the components in optically transparent coatings to be evenly distributed and densely film-forming in their coating, reducing interface roughness and microscopic scattering paths, thereby suppressing haze; organic amine alcohols can adjust the pH of optically transparent coatings to a stable range and suppress phase separation; the surface tension regulation effect of defoamers can improve the surface smoothness of the coating formed by optically transparent coatings; and preservatives ensure that the optically transparent coatings are not disturbed by microorganisms during the film formation process, avoiding surface defects caused by biological contamination.

[0029] Secondly, this application provides a method for preparing an optically transparent coating, comprising the following preparation steps: Provide raw materials for the optically transparent coating according to any embodiment of the first aspect; The raw materials are mixed to obtain an optically transparent coating.

[0030] Through the above implementation methods, the scientific selection and proportioning of raw materials ensure that each functional raw material can play a full role in subsequent steps, laying the foundation for the preparation of optically transparent coatings; the desired optically transparent coating is obtained by mixing the raw materials.

[0031] Furthermore, the method for preparing an optically transparent coating includes the following preparation steps: S1: Providing raw materials for the optically transparent coating according to any embodiment of the first aspect; S2: At 20-30℃, mix water, thickener, defoamer, dispersant, preservative and organic amine alcohol compound, and stir at 300-500 rpm for 20-30 min to obtain the basic aqueous phase; S3: Under conditions of 40-50℃, the basic aqueous phase and the functional modified inorganic filler are mixed and stirred at a rate of 800-1000 rpm for 30-40 minutes to obtain a functional modified inorganic filler dispersion slurry. S4: Under conditions of 30-35℃, the functional modified inorganic filler dispersion slurry, transparent functional particles, and borate ester-silanol-hydroxyl trifunctional crosslinking gel precursor liquid are mixed and stirred at a rate of 400-600 rpm for 20-30 min to obtain an optically transparent coating precursor composite slurry. S5: Under conditions of 20-30℃, the optically transparent coating precursor composite slurry and water-based acrylic copolymer emulsion are mixed and stirred at a rate of 200-300 rpm for 15-20 min, degassed at -0.08 MPa to -0.06 MPa for 10-15 min, and then cured for 16-24 h to obtain an optically transparent coating.

[0032] Through the above implementation methods, the basic aqueous phase system obtained in step S2 effectively regulates the pH value and interfacial tension of the system through the synergistic effect of the dispersant and organic amine alcohol compounds, which can improve the wettability and dispersion stability of subsequent functional modified inorganic fillers and inhibit the agglomeration of any component; the thickener can provide necessary rheological support, stabilize the optical path, and control the haze; the defoamer can quickly break up the microbubbles generated in the optically transparent coating and prevent the bubbles from remaining in the system and forming optical defects. In step S3, the functional modified inorganic filler is uniformly dispersed in the base aqueous phase through a high-shear dispersion process, avoiding the optical shielding effect caused by local accumulation. Because the surface of the functional modified inorganic filler is dense and smooth, and has high interfacial affinity, combined with excellent dispersion stability, it can reduce interfacial roughness, suppress stray light generation, and reduce haze. The aminosilane modified coating layer on the surface of the functional modified inorganic filler can give it good orientation and interfacial wettability, which helps it to achieve orderly arrangement and form a continuous and dense coating structure during the film formation process of the final optically transparent coating. In step S4, the borate-silanol-hydroxyl trifunctional crosslinking gel precursor can fill the microscopic gaps between the functional modified inorganic fillers introduced in step S3, improving the linear transmission capability of light and thus enhancing the overall transmittance. The transparent functional particles have a relatively regular spherical structure, which, combined with the dispersion performance of the borate-silanol-hydroxyl trifunctional crosslinking gel precursor, can synergistically inhibit particle aggregation, improve the optical uniformity of the coating, and reduce haze. At the same time, the borate-silanol-hydroxyl trifunctional crosslinking gel precursor can enhance the compactness and surface continuity of the coating during the film formation process, reduce the formation of microscopic defects, and the transparent functional particles are distributed in the coating as flexible scattering centers, giving it a soft glossy texture, suppressing specular reflection, and improving transmittance. In step S5, the optically transparent coating precursor composite slurry from step S4 is mixed with the waterborne acrylic copolymer emulsion in a set ratio, and the system is uniformly fused under suitable stirring conditions. Subsequently, vacuum degassing and curing treatments are performed to construct a film-forming precursor system with excellent optical properties. The waterborne acrylic copolymer emulsion, as the film-forming matrix, has good optical transparency, flexibility, and good film-forming characteristics. The vacuum degassing process can efficiently remove residual microbubbles and gas inclusions in the mixed system, avoiding the formation of local optical scattering points after film formation and reducing haze. The curing stage promotes molecular rearrangement and interfacial synergistic crosslinking of the components in the system, thereby improving the gloss of the coating.

[0033] Thirdly, this application provides an optically transparent coating prepared according to the method described in the first aspect or the method described in the second aspect, which is suitable for the field of interior and exterior decoration, especially for the surface treatment of imitation stone furniture and the decoration of villa communities, hotels, schools, hospitals, office buildings, existing buildings, and garden landscape structures.

[0034] Compared with the prior art, the beneficial effects of this application are at least as follows: This application constructs an integrated optically transparent structure by introducing transparent functional particles, functionally modified inorganic fillers, and a borate-silanol-hydroxyl trifunctional crosslinked gel precursor into an aqueous acrylate copolymer emulsion film-forming matrix. The transparent functional particles, with their spherical morphology and refractive index approximating the film-forming matrix, provide low-loss direct light transmission, stabilizing the light path and reducing Mie scattering intensity. The functionally modified inorganic fillers, through an aminosilane layer, impart high wettability and stable dispersion to the matrix, preventing agglomeration and mitigating strong light scattering and local optical density fluctuations. Furthermore, the borate-silanol-hydroxyl trifunctional crosslinked gel precursor effectively fills the microscopic gaps within the coating, simultaneously improving surface density and leveling to enhance light transmittance without introducing fogging defects. These multi-scale, cross-interface synergistic mechanisms are coupled in a closed loop within the same film-forming system, ultimately achieving a unified low scattering, high transmission, and controlled reflection of light in the coating. This results in a coating with high transmittance, low haze, and high gloss, while maintaining excellent dispersion stability and film consistency during storage and application. Detailed Implementation

[0035] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0036] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] In this specification, unless otherwise specified, "parts" refers to "parts by weight".

[0039] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0040] The waterborne acrylic copolymer emulsion used is Acronal® S 790 from BASF (China) Co., Ltd. Glass sand, average particle size 5μm; Polyvinylpyrrolidone, number average molecular weight 58,000; Polyvinyl alcohol, number average molecular weight 60,000; Guar gum, number average molecular weight 150,000; Hydroxyethyl cellulose, number average molecular weight 120,000; Snowflake white quartz sand, with an average particle size of 20μm; Calcined white marble with an average particle size of 20μm; Polyether-modified trisiloxane, CAS No.: 67674-67-3, number average molecular weight 2000; Polyoxypropylene ethylene oxide glycerol ether, number average molecular weight 1000; Silicone oil, number average molecular weight 2000; Sodium polyacrylate, number average molecular weight 5000; Lauryl alcohol polyether-4 phosphate, number average molecular weight 800; Dihydroxyethyl tallow amine, number average molecular weight 400; Soybean oil, CAS: 8001-22-7, is industrially refined soybean oil selected from Jingzhou Yinjie Chemical Co., Ltd.

[0041] Preparation Example 1 Preparation of cross-linked polymethyl methacrylate microspheres: M1: Dissolve 100 parts of methyl methacrylate, 15 parts of polyvinylpyrrolidone, and 2 parts of azobisisobutyronitrile in 1500 parts of 60% ethanol aqueous solution and stir at 120 rpm for 1.5 h at 70 °C to obtain a dispersion polymerization reaction system. M2: The dispersion polymerization reaction system and 1.8 parts of ethylene glycol dimethacrylate were stirred at 70°C and 120 rpm for 8.5 h. After centrifugation at 4000 rpm for 15 min, the supernatant was discarded. The precipitate was washed three times with isopropanol (2 times the centrifugation precipitate volume) and then washed twice with water (1 times the centrifugation precipitate volume). After vacuum drying at 50°C for 24 h, cross-linked polymethyl methacrylate microspheres with an average particle size of 5 μm were obtained by air-jet classification.

[0042] Preparation Example 2 Preparation of borate ester-silanol-hydroxyl trifunctional crosslinking gel precursor solution: Eight parts of guar gum, 1.5 parts of borax, 0.8 parts of propyltrimethoxysilane and 67.7 parts of water were mixed and stirred at 600 rpm for 30 min at 50 °C to obtain a borate ester-silanol-hydroxyl trifunctional crosslinked gel precursor solution.

[0043] Preparation Example 3 Preparation of aminosilane-modified snowflake white quartz sand: 100 parts of snowflake white quartz sand, 3 parts of γ-aminopropyltriethoxysilane, and 150 parts of 0.03 mol / L hydrochloric acid solution were dispersed in 400 parts of 35% (v / v) ethanol aqueous solution. The mixture was stirred at 400 rpm for 4 h at 30 °C. After vacuum filtration, the mixture was washed twice with ethanol (twice the volume of the filter cake) and three times with water (twice the volume of the filter cake). The mixture was then vacuum dried at 55 °C for 8 h. After air classification, aminosilane-modified snowflake white quartz sand with an average particle size of 20 μm was obtained.

[0044] Preparation Example 4 Preparation of aminosilane-modified calcined white marble: 100 parts of calcined white marble, 3 parts of γ-aminopropyltriethoxysilane, and 150 parts of 0.03 mol / L hydrochloric acid solution were dispersed in 400 parts of 35% (v / v) ethanol aqueous solution. The mixture was stirred at 400 rpm for 4 h at 30 °C. After vacuum filtration, the mixture was washed twice with ethanol (twice the volume of the filter cake) and three times with water (one times the volume of the filter cake). The mixture was then vacuum dried at 55 °C for 8 h. After air separation, aminosilane-modified calcined white marble with an average particle size of 20 μm was obtained.

[0045] Example 1 A method for preparing an optically transparent coating: S1: 32 parts water; transparent functional particles: 0.78 parts glass sand, 0.42 parts cross-linked polymethyl methacrylate microspheres from Preparation Example 1; functional modified inorganic fillers: 14.4 parts aminosilane-modified snowflake white quartz sand from Preparation Example 3, 3.6 parts aminosilane-modified calcined sand marble from Preparation Example 4; 6.5 parts borate ester-silanol-hydroxyl trifunctional cross-linked gel precursor liquid from Preparation Example 2; thickener: 0.24 parts polyvinyl alcohol, 0.16 parts hydroxypropyl methylcellulose; defoamer: 0.24 parts polyether-modified trisiloxane, 0.02 parts silicone oil; dispersant: 0.6 parts sodium polyacrylate; preservative: 0.14 parts phenoxyethanol, 0.06 parts sodium benzoate; organic amine alcohols: 0.4 parts 2-amino-2-methyl-1-propanol; 25 parts aqueous acrylate copolymer emulsion; S2: At 25°C, water, thickener, defoamer, dispersant, preservative, and 2-amino-2-methyl-1-propanol are mixed and stirred at 450 rpm for 25 min to obtain the basic aqueous phase. S3: At 45℃, the basic aqueous phase, aminosilane-modified snowflake white quartz sand, and aminosilane-modified calcined white marble sand are mixed and stirred at 1000 rpm for 30 min to obtain a functional inorganic filler dispersion slurry. S4: Under the condition of 35°C, the functional inorganic filler dispersion slurry, cross-linked polymethyl methacrylate microspheres, glass sand, and borate ester-silanol-hydroxyl trifunctional cross-linked gel precursor liquid are mixed and stirred at a rate of 550 rpm for 25 min to obtain an optically transparent coating precursor composite slurry. S5: At 25°C, the optically transparent coating precursor composite slurry and water-based acrylic copolymer emulsion are mixed, stirred at 300 rpm for 15 min, degassed at -0.08 MPa for 10 min, and then cured for 18 h to obtain an optically transparent coating.

[0046] Example 2 For the preparation of an optically transparent coating: The formulation is largely the same as Example 1, except that glass sand is replaced with an equal mass of cross-linked polymethyl methacrylate microspheres.

[0047] Example 3 For the preparation of an optically transparent coating: The formulation is largely the same as Example 1, except that the cross-linked polymethyl methacrylate microspheres are replaced with an equal mass of glass frit.

[0048] Example 4 For the preparation of an optically transparent coating: The formula is largely the same as Example 1, except that aminosilane-modified calcined white marble is replaced with an equal mass of aminosilane-modified snowflake white quartz sand.

[0049] Example 5 For the preparation of an optically transparent coating: The formula is largely the same as Example 1, except that aminosilane-modified calcined white marble is used instead of aminosilane-modified snowflake quartz sand in the same mass.

[0050] Comparative Example 1 The formulation is largely the same as Example 1, except that the borate-silanol-hydroxyl trifunctional crosslinking gel precursor solution was not added.

[0051] Comparative Example 2 The formula is largely the same as Example 1, except that the aminosilane-modified snowflake white quartz sand is replaced with snowflake white quartz sand.

[0052] Comparative Example 3 The formula is largely the same as Example 1, except that the aminosilane-modified calcined white marble is replaced with calcined white marble.

[0053] Comparative Example 4 The formulation is largely the same as Example 1, except that 6.5 parts of borate ester-silanol-hydroxyl trifunctional crosslinking gel precursor solution are replaced with its raw materials, namely 0.67 parts guar gum, 0.13 parts borax, 0.07 parts propyltrimethoxysilane and 5.63 parts water.

[0054] Test section Test sample preparation: 5g of optically transparent paint was placed on one end of a degreased glass plate, and the paint was applied by scraping at a speed of 100mm / s using a paint film applicator to form a smooth paint film. After drying at 110℃ for 40min, the plate was left to stand at 25℃ and 50% relative humidity for 24h to obtain the test sample. Transmittance and haze testing: Transmittance and haze were tested using a haze meter in accordance with the national standard GB / T 2410-2008.

[0055] Gloss test: Referring to the national standard GB / T 9754-2007, a gloss meter is used to test the gloss when the axis of the incident beam is at 20° and 60° to the normal of the test surface.

[0056] The test results are shown in Table 1: Table 1

[0057] As shown in Table 1, each embodiment is superior to the comparative example in terms of transmittance, haze and gloss. This may be because the borate ester-silanol-hydroxyl trifunctional crosslinking gel precursor liquid was not added in comparative example 1, so the micro gaps inside the coating could not be filled, the lack of synergistic scattering structure, the unstable distribution of optical interface inside the coating film, the reduced transmittance and gloss and the increased haze. Comparative Example 2 directly used unmodified snowflake white quartz sand, which had insufficient bonding force with the film-forming matrix of waterborne acrylic copolymer emulsion, resulting in agglomeration and Mie scattering, leading to reduced light transmittance and gloss, and increased haze. Comparative Example 3 uses unmodified calcined white marble, which has insufficient bonding force with the film-forming matrix of water-based acrylic copolymer emulsion, resulting in agglomeration and Mie scattering, leading to reduced light transmittance and gloss, and increased haze. Comparative Example 4 directly replaced the borate ester-silanol-hydroxyl trifunctional crosslinking gel precursor with borate ester-silanol-hydroxyl trifunctional crosslinking gel precursor. During the film formation process, a stable crosslinking network could not be formed, the micro gaps inside the coating could not be fully filled, and the refractive index transition layer was not fully constructed, resulting in reduced light transmittance and gloss, and increased haze.

[0058] As shown in Examples 1-3, the mass ratio of glass sand to cross-linked polymethyl methacrylate microspheres has a certain influence on the transmittance, haze, and gloss of the coating formed by the optically transparent coating. When the mass ratio of glass sand to cross-linked polymethyl methacrylate microspheres is 65:(30-40), the transmittance and gloss of the coating formed by the optically transparent coating are higher, and the haze is lower. This may be because cross-linked polymethyl methacrylate microspheres are more inclined to flexible scattering and interface homogenization effect, but the overall light path is biased towards scattering, while glass sand has the advantages of direct light transmission and specular reflection.

[0059] As shown in Examples 1, 4, and 5, the mass ratio of aminosilane-modified snowflake white quartz sand and aminosilane-modified calcined white marble has a certain influence on the light transmittance, haze, and gloss of the coating formed by the optically transparent paint. When the mass ratio of aminosilane-modified snowflake white quartz sand to aminosilane-modified calcined white marble is 80:(15-25), the light transmittance and gloss of the coating formed by the optically transparent paint are higher, and the haze is lower. This may be because aminosilane-modified snowflake white quartz sand is more inclined to maintain high light transmittance and optical uniformity, while aminosilane-modified calcined white marble is more inclined to improve gloss and have the advantage of surface leveling.

[0060] The optically transparent coating obtained in Preparation Example 1 was used to prepare test samples. Following the same UV aging treatment as GB / T 14522-2008 and the same damp heat treatment as GB / T 1740-2007, transmittance, haze, and gloss tests were performed. The results showed transmittance, haze, 20° gloss, and 60° gloss were 85.7%, 7.3%, 69 GU, and 80 GU, respectively. Adhesion was tested according to GB / T 9286-2021, and the adhesion grade was 0. Stain resistance was tested according to GB / T 9780-2013, and the stain resistance grade was also 0.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A coating with optical transparency, characterized in that, Includes the following quantities of raw materials: The composition includes: 25 parts waterborne acrylate copolymer emulsion, 25-35 parts water, 0.8-1.5 parts transparent functional particles, 16-20 parts functional modified inorganic filler, 5.5-7.5 parts borate ester-silicone-hydroxyl trifunctional crosslinking gel precursor, 0.2-0.5 parts thickener, 0.2-0.4 parts defoamer, 0.5-1 part dispersant, 0.1-0.3 parts preservative, and 0.2-0.5 parts organic amine alcohols. The transparent functional particles include at least one of glass sand and cross-linked polymethyl methacrylate microspheres; the functional modified inorganic fillers include at least one of aminosilane modified snowflake white quartz sand and aminosilane modified calcined white marble.

2. The optically transparent coating according to claim 1, characterized in that, The cross-linked polymethyl methacrylate microspheres are prepared by the following steps: M1: Methyl methacrylate, dispersant, and initiator are dissolved in a low alcohol aqueous solution to homopolymerize methyl methacrylate free radicals into monodisperse polymethyl methacrylate seed microspheres, thus obtaining a dispersion polymerization reaction system; M2: Mix the dispersion polymerization reaction system and the crosslinking agent to allow the crosslinking agent to polymerize and form a crosslinked network structure with the polymethyl methacrylate seed microspheres to obtain crosslinked polymethyl methacrylate microspheres; The dispersant is polyvinylpyrrolidone; the lower alcohol includes at least one of ethanol and isopropanol; the initiator includes at least one of azobisisobutyronitrile and benzoyl peroxide; and the crosslinking agent includes at least one of ethylene glycol dimethacrylate and trimethylolpropane triacrylate.

3. The optically transparent coating according to claim 1, characterized in that, The borate ester-silanol-hydroxyl trifunctional crosslinked gel precursor solution includes the following preparation steps: A functional polymer thickener, borax, and silanol compounds are mixed with water. Boric acid generated from the hydrolysis of borax undergoes borate esterification with the hydroxyl groups of the functional polymer thickener, and the silanol groups of the silanol compounds condense with the hydroxyl groups on the borax or the functional polymer thickener to obtain a borate ester-silanol-hydroxyl trifunctional crosslinked gel precursor solution. The functional polymer thickener includes at least one of polyvinyl alcohol, guar gum, hydroxypropyl methylcellulose, and hydroxyethyl cellulose; the silanol compound includes at least one of propyltrimethoxysilane and ethyltrimethoxysilane.

4. The optically transparent coating according to claim 3, characterized in that, The borate ester-silanol-hydroxyl trifunctional crosslinked gel precursor solution includes the following preparation steps: Mix 8 parts of functional polymer thickener, 1-2 parts of borax, 0.5-2 parts of silanol compound with 65-70 parts of water, and stir at 300-600 rpm for 30-60 min at 40-60℃ to obtain borate ester-silanol-hydroxyl trifunctional crosslinked gel precursor solution.

5. The optically transparent coating according to claim 1, characterized in that, The aminosilane-modified snowflake white quartz sand comprises the following preparation steps: Snowflake white quartz sand, aminosilane coupling agent, and hydrochloric acid solution are dispersed in an ethanol aqueous solution. The silanol groups generated by the hydrolysis of the silane coupling agent undergo a condensation reaction with the hydroxyl groups formed on the surface of the snowflake white quartz sand under acidic conditions to obtain aminosilane modified snowflake white quartz sand. The aminosilane coupling agent includes at least one of γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

6. The optically transparent coating according to claim 1, characterized in that, The preparation steps of the aminosilane-modified calcined white marble are as follows: Calcined sand white marble, silane coupling agent, and hydrochloric acid solution are dispersed in an ethanol aqueous solution. The silanol groups generated by the hydrolysis of the silane coupling agent undergo a condensation reaction with the hydroxyl groups formed on the surface of the calcined sand white marble under acidic conditions to obtain aminosilane modified calcined sand white marble. The aminosilane coupling agent includes at least one of γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

7. The optically transparent coating according to claim 1, characterized in that, The transparent functional particles comprise glass sand and cross-linked polymethyl methacrylate microspheres; wherein the mass ratio of the glass sand to the cross-linked polymethyl methacrylate microspheres is 65:(30-40).

8. The optically transparent coating according to claim 1, characterized in that, The functional modified inorganic filler includes aminosilane-modified snowflake white quartz sand and aminosilane-modified calcined white marble sand; wherein the mass ratio of aminosilane-modified snowflake white quartz sand and aminosilane-modified calcined white marble sand is 80:(15-25).

9. The optically transparent coating according to claim 1, characterized in that: 1) The aqueous acrylate copolymer emulsion is model Acronal® S 790; 2) The thickener includes at least one of polyvinyl alcohol, hydroxypropyl methylcellulose, and hydroxyethyl cellulose; 3) The defoamer includes at least one of polyether-modified trisiloxane, polyoxypropylene ethylene oxide glycerol ether, and silicone oil; 4) The dispersant includes at least one of sodium polyacrylate, lauryl ether-4 phosphate, and dihydroxyethyl tallow amine; 5) The preservative includes at least one of sodium benzoate and phenoxyethanol; 6) The organic amine alcohols include at least one of triethanolamine, 2-amino-2-methyl-1-propanol, and N-methyldiethanolamine.

10. A method for preparing a coating with optical transparency, characterized in that, The preparation steps include the following: Provide raw materials for the optically transparent coating according to any one of claims 1-9; The raw materials are mixed to obtain an optically transparent coating.

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