A matte varnish and a method for preparing the same

Abstract

The application provides a matte varnish and a preparation method thereof. The matte varnish comprises the following raw materials in parts by mass: 50 parts of water-based acrylic resin, 5-15 parts of modified matting agent, 0.05-0.2 parts of defoaming agent, 1-2 parts of film-forming aid, 0.2-1 parts of thickening agent, 0.1-0.2 parts of pH regulator and 40-60 parts of water. The modified matting agent comprises an inorganic matrix and an organic / silicone composite layer coated on the surface of the inorganic matrix. The inorganic matrix comprises talcum powder and barium sulfate. The organic / silicone composite layer comprises a sodium lignosulfonate layer and a silicone structure formed by solidification of water glass. The matte varnish prepared by the multi-stage rough structure design of the modified matting agent has excellent matte performance and can be widely applied to painting scenes with high requirements for matte effect.

Description

Technical Field

[0001] This application relates to the field of coating technology, specifically to a matte varnish and its preparation method. Background Technology

[0002] Matte varnishes are a type of transparent or semi-transparent coating material that reduces the specular reflection intensity of the coating surface, giving the coated object a low-gloss or non-reflective appearance. They are widely used in architectural decoration, stone protection, furniture coating, floor protection, and industrial product surface treatment. Compared to high-gloss or semi-gloss varnishes, matte varnishes effectively reduce visual interference caused by strong reflections, resulting in a more natural and softer visual effect on the substrate surface. They are particularly suitable for applications requiring high visual comfort, surface texture, and decorative harmony, and their application demand in the high-end decorative and functional coating fields has been continuously increasing in recent years.

[0003] Currently, matte varnishes often employ the method of introducing inorganic matting agents into the film-forming resin system. By creating a certain degree of microscopic roughness on or within the coating film, incident light is scattered multiple times, thereby reducing the specular reflection intensity of the coating film. Common matting methods mainly rely on single-scale particulate fillers, and their matting effect is limited to some extent by particle size, dispersion state, and compatibility with the resin matrix.

[0004] In practical applications, conventional inorganic matting agents, when added at low levels, struggle to form a sufficiently dense and continuous scattering structure, resulting in a limited reduction in coating gloss. Conversely, increasing the amount of matting agent to achieve even lower gloss often leads to problems such as reduced film transparency, whitening, increased haze, and a rougher surface feel. It can also negatively impact application leveling and film integrity. Conventional inorganic matting agents have poor compatibility with resin matrices, easily detaching or structurally damaging after abrasion, potentially leading to insufficient abrasion resistance, a decrease in matte finish (gloss recovery), and poor matte stability. This issue is particularly pronounced in high-frequency contact and abrasion-prone applications such as furniture, flooring, and instrument housings.

[0005] Therefore, there is an urgent need for a matte clear varnish technology that can achieve a stable low-gloss effect of water-based clear varnishes while ensuring matte stability by improving abrasion resistance and mitigating matte failure caused by wear. Summary of the Invention

[0006] This application provides a matte varnish and its preparation method.

[0007] In a first aspect, this application provides a matte varnish comprising the following raw materials in parts by weight:

[0008] The mixture comprises 50 parts of waterborne acrylic resin, 5-15 parts of modified matting agent, 0.05-0.2 parts of defoamer, 1-2 parts of film-forming aid, 0.2-1 parts of thickener, 0.1-0.2 parts of pH adjuster, and 40-60 parts of water. The modified matting agent comprises an inorganic matrix and an organic / siloxane composite layer coated on the surface of the inorganic matrix. The inorganic matrix comprises talc and barium sulfate. The organic / siloxane composite layer comprises a sodium lignosulfonate layer and a silicon-oxygen structure formed by curing water glass.

[0009] According to this application, by introducing a modified matting agent with a multi-level rough surface structure into the varnish system through the above-mentioned formulation design, it is helpful to achieve an excellent matte effect.

[0010] Specifically, the modified matting agent uses talc and barium sulfate as an inorganic particulate matrix. The talc has a lamellar structure, which facilitates the creation of surface undulations at the micrometer scale, disrupting the specular reflection conditions of the coating surface. The barium sulfate has a fine-grained or near-spherical particle structure, possessing relatively stable particle morphology and dispersion characteristics, contributing to a relatively uniform distribution in the coating. The combined effect of the particle size and the refractive index difference between the talc and barium sulfate and the resin system enhances the scattering of incident light. This composite of two inorganic materials, acting as a matting framework, forms a basic rough structure in the coating, providing an effective carrier for light scattering. Simultaneously, the stacked structure of the lamellar talc and the filling effect of the high-hardness barium sulfate may prevent the overall morphology of the matting interface from collapsing rapidly, helping to delay the passivation of the matting structure during wear, inhibiting the destruction of the rough structure, and providing a fundamental guarantee for matte stability.

[0011] Furthermore, the organic / silicon-oxygen composite layer comprises a sodium lignosulfonate layer and a silicon-oxygen structure formed by water glass curing. Sodium lignosulfonate is anchored to the surface of the inorganic matting matrix through multi-point adsorption. The adsorption configuration of its molecular chains on the particle surface exhibits a certain degree of randomness and inhomogeneity, promoting the formation of a flexible, non-smooth organic interface on the particle surface. This further refines the surface roughness based on the macroscopically rough structure of the inorganic matrix and provides a non-uniform interface template for the subsequent deposition of silicon-oxygen structures, thus limiting the aggregation of silicon-oxygen structures on the particle surface to a certain extent. Water glass cures under the regulation of this organic interface, and the resulting amorphous hydrated silicon-oxygen structures tend to be distributed on the particle surface in a discontinuous, micro-protrusion form. The silicon-oxygen structures and the sodium lignosulfonate layer are spatially interwoven, forming... On the one hand, the organic / silicon-oxygen synergistic interface introduces a multi-level rough structure composed of organic interface refinement and silicon-oxygen micro-protrusions on the basis of the macroscopic rough structure provided by the inorganic matrix. This allows incident light to be continuously scattered, refracted, and reflected multiple times at different scales, thereby enhancing light dissipation efficiency and helping to achieve a low-gloss effect. On the other hand, during friction or wear, the flexible buffering effect provided by the sodium lignosulfonate layer may reduce the shedding of silicon-oxygen micro-protrusions, while the certain hardness support provided by the silicon-oxygen structure helps to inhibit the rapid wear of the secondary rough structure. The synergistic effect of the two effectively delays the passivation process of the matte microstructure, thereby improving the wear resistance stability of the matte effect.

[0012] In summary, this application constructs an integrated modified matting agent by combining talc, barium sulfate, and an organic / siloxane composite coating layer. The inorganic matrix provides a relatively stable adhesion substrate and macroscopic scattering framework for the coating layer, ensuring the overall integrity of the matting structure. The coating layer refines the roughness of the inorganic matrix surface, increases scattering sites, and helps to slow down the decay of the matte effect during use. It is suitable for water-based clear varnish applications with high requirements for appearance and texture.

[0013] In some embodiments, the raw materials further include melamine-modified urea-formaldehyde resin, wherein the mass ratio of the waterborne acrylic resin to the melamine-modified urea-formaldehyde resin is 1:0.04~0.06.

[0014] In some of the above embodiments, by introducing melamine-modified urea-formaldehyde resin into the waterborne acrylic varnish system, a limited degree of interaction can occur between the resin and the waterborne acrylic resin during film formation, forming local microscale structural units. Compared to unmodified urea-formaldehyde resin, the introduction of the melamine structure allows the urea-formaldehyde resin to participate in the coating structure construction in a discontinuous and non-uniform form during film formation, thereby introducing local structural differences into the coating surface. The introduced structural inhomogeneity weakens the specular reflection conditions of the coating surface through multi-scale structural coupling and, together with the modified matting agent, constructs a synergistic matting system: talc in the modified matting agent may undergo oriented stacking during film formation, and its plate-like structure constructs a macroscopic undulating morphology on the coating surface, causing primary scattering of incident light with disrupted directionality. This provides the preconditions for further adjustment of light by the subsequent fine-scale structure. Barium sulfate particles and silicon-oxygen structures are more easily distributed in local areas between macroscopic undulations, forming a fine-scale concave-convex structure, which helps to cause the light after primary scattering to undergo rescattering and refraction at local interfaces, reducing the possibility of light reconverging to form specular reflection. The aforementioned macroscopic and microscopic structures may exhibit a nested distribution in space, promoting the continuous occurrence of scattering processes at different scales. Furthermore, melamine-modified urea-formaldehyde resin and waterborne acrylic acid... Resins may interact at local interfaces. The micro-crosslinked structure formed by melamine-modified urea-formaldehyde resin during film formation continues to distribute among the aforementioned multi-scale rough structures, thereby further introducing discontinuities in refractive index and interface orientation on the basis of the original geometric rough structure. It may also slightly anchor barium sulfate particles and silicon oxide micro-protrusions through polar interactions, reducing their tendency to redistribute or aggregate. This helps to prevent the nested distribution of fine-scale concave-convex structures and macroscopic undulations from being disrupted. Furthermore, by restricting the redistribution and flow of resin segments near the scattering interface, the micro-crosslinked structure maintains the scattering conditions originally composed of geometric roughness and refractive index discontinuities, thereby mitigating the tendency of the coating surface to regain specular reflection characteristics during film formation or use. From the perspective of optical interface control, this enhances the suppression effect of the multi-level scattering structure on residual specular reflection light. When the mass ratio of waterborne acrylic resin to melamine-modified urea-formaldehyde resin is in the range of 1:0.04~0.06, the resulting microscale structural units are more likely to participate in the construction of the matting interface in a moderately distributed manner, so that they can cooperate with the multiscale structure formed by the modified matting agent. This enhances the light scattering effect while reducing the impact of structural scale imbalance on matte stability, which is conducive to obtaining a good low-gloss matte effect.

[0015] In some embodiments, the modified matting agent is prepared by the following steps:

[0016] S1: Disperse talc, barium sulfate, and sodium lignosulfonate in water, so that sodium lignosulfonate undergoes physical adsorption and interfacial interaction with the surface of inorganic particles to form a lignin layer coated on the surface of the inorganic matrix, thus obtaining a lignin-coated matting agent.

[0017] S2: The lignin-coated matting agent and water glass are dispersed in an ethanol-water solution, so that the water glass forms a silicon-oxygen structure and is deposited in situ on the surface of the lignin-coated layer to obtain the modified matting agent.

[0018] In some of the above embodiments, talc and barium sulfate are coated with decolorized sodium lignin sulfonate, and water glass is deposited on the surface of the lignin coating layer through hydrolysis and condensation reaction to form a silicon-oxygen structure. The resulting integrated matting agent achieves multi-level regulation of the surface structure, introduces a multi-scale rough structure that is conducive to light scattering, and helps to improve the matte performance of the varnish coating.

[0019] In some embodiments, the decolorized sodium lignin sulfonate described in step S1 is prepared by the following steps:

[0020] Sodium lignosulfonate and hydrogen peroxide were dispersed in water for decolorization treatment. Disodium ethylenediaminetetraacetate was added to cause the metal ion impurities in lignin to complex with the disodium ethylenediaminetetraacetate, thus obtaining decolorized sodium lignosulfonate.

[0021] In some of the above embodiments, untreated sodium lignosulfonate is typically brownish-red, and its direct introduction can easily lead to yellowing or graying of the coating film, which is not conducive to obtaining a uniform, low-gloss coating film. Therefore, before using sodium lignosulfonate as an inorganic matting agent coating component, this application performs a decolorization treatment. This is achieved by using hydrogen peroxide for decolorization, combined with the complexing effect of disodium ethylenediaminetetraacetate on metal ion impurities, thereby reducing the color depth of sodium lignosulfonate and improving its appearance suitability in varnish systems. After the above decolorization treatment, sodium lignosulfonate still maintains good interfacial interaction capabilities in aqueous systems, and can form a relatively continuous and stable coating layer on the surface of the inorganic matting substrate.

[0022] In some embodiments, the decolorized sodium lignin sulfonate described in step S1 is prepared by the following steps:

[0023] Disperse 10 parts of sodium lignosulfonate and 1-10 parts of 3wt%-10wt% hydrogen peroxide in 10-50 parts of water, adjust the pH to 8-9, react at 40-60℃ for 10-60 min, add 0.1-0.3 parts of disodium ethylenediaminetetraacetate, react for 10-60 min to obtain decolorized sodium lignosulfonate.

[0024] In some of the above embodiments, a method for preparing decolorized sodium lignin sulfonate is specifically described. Through the above decolorization treatment, the decolorized sodium lignin sulfonate obtained can meet the color requirements of varnish while still participating in the construction of multi-level matting structure as an organic coating component on the surface of inorganic matting agent, thus taking into account both appearance performance and matting efficiency.

[0025] In some embodiments, fumed silica is also added in step S1, wherein the mass ratio of the decolorized sodium lignosulfonate to fumed silica is 1:0.2~0.35.

[0026] In some of the above embodiments, the fumed silica added in step S1 can act together with the decolorizing sodium lignin sulfonate on the surface of talc and barium sulfate particles. The fumed silica exists in the form of dispersed nanoparticles, and the surface silanol groups can interact with the hydroxyl groups in the decolorizing sodium lignin sulfonate molecules through hydrogen bonding, causing the fumed silica to distribute within the lignin adsorption layer. This fumed silica can serve as a nanoscale structural perturbation unit, potentially regulating the spatial configuration of the lignin adsorption layer. This helps to improve the microscopic roughness of the matting particle surface, complementing the macroscopic undulations of talc and the fine-scale irregularities of barium sulfate, thus perfecting the multi-level rough structure, enhancing the scattering ability of incident light, and serving as a local structure-inducing site during subsequent water glass hydrolysis and silicon-oxygen structure formation, which is beneficial for the in-situ generation of silicon-oxygen structures on the surface of the matting particles. Meanwhile, nanoscale fumed silica can be distributed between the inorganic matrix formed by the modified matting agent and its outer organic coating structure, providing local support within the matting structure. This helps reduce the probability of concentrated damage or local collapse of the coating layer at microscopic protrusions, allowing the surface roughness structure constructed by the matting filler to be better preserved. Furthermore, the introduction of fumed silica particles does not significantly change the macroscopic undulation morphology of the coating surface, but may stabilize the existing multi-scale matting structure. Under friction conditions, it may, to some extent, slow down the tendency of the surface micro-protrusion structure to be polished or flattened, thus helping to maintain the effectiveness of the scattering structure on the coating surface and reducing the probability of gloss recovery. When the mass ratio of decolorizing sodium lignosulfonate to fumed silica is controlled within the range of 1:0.2~0.35, it helps to obtain a more stable matte clear varnish coating.

[0027] In some embodiments, a silane coupling agent is also added in step S2. The silane coupling agent includes γ-aminopropyltriethoxysilane, and the mass ratio of the silane coupling agent to the lignin-coated matting agent is 0.05~0.2:10.

[0028] In some of the above embodiments, the introduction of silane coupling agents helps to regulate the interfacial state between the modified matting agent and the waterborne acrylic varnish system, enabling the matting component to participate in the construction of the coating surface structure in a relatively stable form during film formation. γ-aminopropyltriethoxysilane facilitates the formation of a relatively uniformly distributed multiphase structure of the matting component on the coating surface, reducing the interference of local enrichment or scale abrupt changes on the surface scattering structure, thereby helping to improve the uniformity of the matte effect and, to some extent, reducing the migration or peeling tendency of matting particles in the surface structure, thus improving the stability of the low-gloss state.

[0029] In some embodiments, the modified matting agent is prepared by the following steps:

[0030] S1: Disperse 1 part of decolorizing sodium lignosulfonate, 0.2~0.35 parts of fumed silica, 10~50 parts of talc, and 5~30 parts of barium sulfate in 10~100 parts of water, and react at 40~60℃ for 10~60 min to obtain a lignin-coated matting agent.

[0031] S2: Disperse 10 parts of lignin-coated matting agent, 0.2-0.8 parts of water glass, and 0.05-0.2 parts of γ-aminopropyltriethoxysilane in 10-50 parts of ethanol-water solution, adjust the pH to 8.5-9.5, and react at 40-60℃ for 10-60 min to obtain the modified matting agent.

[0032] In some of the above embodiments, the preparation method of the modified matting agent is specifically described. By controlling the amount and reaction conditions of decolorizing sodium lignosulfonate, fumed silica, talc, barium sulfate, water glass and γ-aminopropyltriethoxysilane, a multi-scale matting structure is formed. Under the synergistic effect of each component, the wear resistance of the matting agent is improved, and an excellent and stable matting effect can be achieved.

[0033] In some embodiments, the defoamer includes a mineral oil-based defoamer. Based on the above embodiments, mineral oil-based defoamers are suitable for water-based systems, have good compatibility with resins, and do not affect the transparency and matte uniformity of the varnish.

[0034] In some embodiments, the film-forming aid includes ester-based film-forming aids. Based on the above embodiments, ester-based film-forming aids exhibit good compatibility with waterborne acrylic resins, resulting in dense films with moderate evaporation rates.

[0035] In some embodiments, the thickener includes an acrylic thickener. Based on the above embodiments, acrylic thickeners have excellent compatibility with the same resin system and do not interfere with the dispersion of matting particles.

[0036] In some embodiments, the pH adjuster includes an organic amine pH adjuster. Based on the above embodiments, organic amine pH adjusters can gently stabilize aqueous emulsions without corroding the substrate.

[0037] In some embodiments, the talc powder has an average flake size of 1-10 μm, and the barium sulfate has an average particle size of 50-200 nm. Based on the above embodiments, this size combination is beneficial for constructing a rough structure that progresses from the micrometer scale to the nanometer scale in the coating, thereby enhancing the multi-scale light scattering effect.

[0038] In some embodiments, the average particle size of the fumed silica is 1-20 nm. Based on the above embodiments, this nanoscale size can introduce fine-scale structural perturbations at low addition levels, improving the overall roughness of the system, while avoiding the impact of excessively large particles on the transparency of the coating.

[0039] Secondly, this application provides a method for preparing a matte varnish, characterized in that it includes:

[0040] Provide the raw materials included in the matte varnish according to any embodiment of the first aspect;

[0041] The raw materials are blended to obtain a matte varnish.

[0042] According to this application, by using the raw materials of the matte varnish described in any embodiment of the first aspect and blending them under controlled rotation speed conditions, the water-based acrylic resin, modified matting agent, defoamer, film-forming aid, thickener, pH adjuster and water are uniformly dispersed during the mixing process, thereby fully exerting their matting effect during the film-forming process, and the matte varnish described in the first aspect can be prepared. Therefore, this preparation method also has the beneficial effects described in the first aspect, and the varnish obtained has low gloss matte properties.

[0043] Compared with the prior art, the beneficial effects of this application are at least as follows:

[0044] This application constructs a sodium lignosulfonate / silica composite coating layer on the surface of an inorganic matrix of talc and barium sulfate. This allows the inorganic matrix and coating layer to form a synergistic matting structure system within the coating film, creating a multi-level surface scattering structure. The inorganic framework composed of talc and barium sulfate provides a micron-level undulating structure on the coating surface, which helps to disrupt the specular reflection conditions of the coating surface, causing primary scattering of incident light. The sodium lignosulfonate layer in the coating layer can regulate the optical interface state of the matting filler surface, resulting in a more macroscopically continuous scattering interface distribution of the inorganic matrix within the coating film. This reduces the possibility of forming localized strong reflection points. The silica structure introduces finer-scale roughness features onto the inorganic framework surface, further deflecting and scattering the light after primary scattering. The superposition of scattering interfaces at different scales reduces the probability of directional reflection of incident light, thereby weakening the specular reflection intensity of the coating film and achieving a low-gloss matte appearance. Detailed Implementation

[0045] 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.

[0046] 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.

[0047] 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.

[0048] In this specification, unless otherwise specified, "parts" refers to "parts by weight".

[0049] 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.

[0050] Water-based acrylic resin: Model: Neocryl A-1188;

[0051] Melamine-modified urea-formaldehyde resin: free formaldehyde ≤0.3%, melamine content 10wt%;

[0052] Sodium lignosulfonate: CAS number 8061-51-6, weight average molecular weight approximately 8000;

[0053] Barium sulfate: average particle size approximately 100 nm;

[0054] Talc: average flake diameter approximately 5μm, silicon content approximately 60wt%;

[0055] Fumed silica: average particle size approximately 10 nm;

[0056] Water glass: Sodium water glass, Baumé degree approximately 40, molar ratio of SiO2 to Na2O approximately 3.2;

[0057] Defoamer: NOPCO SN1340;

[0058] Film-forming aid: dodecyl alcohol ester, CAS number 25265-77-4;

[0059] pH adjuster: 2-amino-2-methyl-1-propanol, CAS number 124-68-5;

[0060] Thickener: ACRYSOL DR-50;

[0061] γ-aminopropyltriethoxysilane: CAS number 919-30-2.

[0062] Preparation Example 1

[0063] Preparation of decolorized sodium lignin sulfonate:

[0064] Disperse 10 parts of sodium lignosulfonate in 30 parts of water and stir for 10 min. Add 8 parts of 7.5% hydrogen peroxide and adjust the pH to 8.5 with 0.5 wt% ammonia. React at 50℃ for 60 min. Add 0.2 parts of disodium ethylenediaminetetraacetate and react at 50℃ for 30 min. Filter and adjust the pH of the filtrate to 3.5 with 1 mol / L hydrochloric acid aqueous solution. Stir for 10 min, filter, wash, and vacuum dry to obtain decolorized sodium lignosulfonate.

[0065] Preparation Example 2

[0066] Preparation of modified matting agents:

[0067] S1: Disperse 1 part of decolorizing sodium lignin sulfonate in 50 parts of deionized water and stir for 10 min. Add 0.3 parts of fumed silica under stirring and stir for 15 min. Add 30 parts of talc and 10 parts of barium sulfate in three portions under stirring, stirring for 5 min after each addition. After all the materials are added, stir for 15 min and react at 50℃ for 30 min. Filter, wash with deionized water, and dry at 60℃ to obtain lignin-coated matting agent.

[0068] S2: Disperse 10 parts of lignin-coated matting agent in 50 parts of ethanol-water solution (40 parts of deionized water and 10 parts of anhydrous ethanol), add 0.6 parts of water glass, stir for 5 min, and continue to slowly add 0.1 parts of γ-aminopropyltriethoxysilane under stirring, continue stirring for 10 min, adjust the pH value to 9 with 0.5 wt% ammonia water, react at 50℃ for 30 min, filter, wash with deionized water, and vacuum dry at 70℃ to obtain modified matting agent A.

[0069] Preparation Example 3

[0070] Preparation of modified matting agents:

[0071] The preparation method is largely the same as in Example 2, except that fumed silica was not added in step S1. Specifically, the difference is as follows:

[0072] S1: Disperse 1 part of decolorizing sodium lignin sulfonate in 50 parts of deionized water and stir for 10 min. Under stirring conditions, add 30 parts of talc powder and 10 parts of barium sulfate in three portions, and continue stirring for 5 min after each addition. After all the materials are added, stir for 15 min and react at 50℃ for 30 min. Filter, wash with deionized water, and dry at 60℃ to obtain lignin-coated matting agent.

[0073] The process is the same as step S2, yielding modified matting agent B.

[0074] Preparation Example 4

[0075] Preparation of modified matting agents:

[0076] The preparation method is largely the same as in Example 2, except for the change in the mass of fumed silica added in step S1. Specifically, the difference lies in:

[0077] S1: Disperse 1 part of decolorizing sodium lignin sulfonate in 50 parts of deionized water and stir for 10 min. Add 0.1 part of fumed silica under stirring and stir for 15 min. Add 30 parts of talc and 10 parts of barium sulfate in three portions under stirring, and continue stirring for 5 min after each addition. After all the materials are added, stir for 15 min and react at 50℃ for 30 min. Filter, wash with deionized water, and dry at 60℃ to obtain lignin-coated matting agent.

[0078] The process is the same as step S2, yielding modified matting agent C.

[0079] Preparation Example 5

[0080] Preparation of modified matting agents:

[0081] The preparation method is largely the same as in Example 2, except for the change in the mass of fumed silica added in step S1. Specifically, the difference lies in:

[0082] S1: Disperse 1 part of decolorizing sodium lignin sulfonate in 50 parts of deionized water and stir for 10 min. Add 0.5 parts of fumed silica under stirring and stir for 15 min. Add 30 parts of talc and 10 parts of barium sulfate in three portions under stirring, stirring for 5 min after each addition. After all the materials are added, stir for 15 min and react at 50℃ for 30 min. Filter, wash with deionized water, and dry at 60℃ to obtain lignin-coated matting agent.

[0083] The process is the same as step S2, yielding the modified matting agent D.

[0084] Preparation Example 6

[0085] Preparation of modified matting agents:

[0086] The preparation method is largely the same as in Example 2, except that γ-aminopropyltriethoxysilane was not added in step S2. Specifically, the difference is as follows:

[0087] S2: Disperse 10 parts of lignin-coated matting agent in 50 parts of ethanol-water solution (40 parts of deionized water and 10 parts of anhydrous ethanol), add 0.6 parts of water glass, stir for 15 min, adjust the pH value to 9 with 0.5 wt% ammonia water, react at 50℃ for 30 min, filter, wash with deionized water, and vacuum dry at 70℃ to obtain modified matting agent E.

[0088] Comparative Preparation Example 1

[0089] Preparation of modified matting agents:

[0090] S1: Disperse 1 part of decolorizing sodium lignin sulfonate in 50 parts of deionized water and stir for 10 min. Under stirring conditions, add 30 parts of talc powder and 10 parts of barium sulfate in three portions, stirring for 5 min after each addition. After all the materials are added, stir for 15 min and react at 50℃ for 30 min. Filter, wash with deionized water, and dry at 60℃ to obtain lignin-coated matting agent, which is used as modified matting agent F.

[0091] Comparative Preparation Example 2

[0092] Preparation of modified matting agents:

[0093] S1: Disperse 7.5 parts talc powder and 2.5 parts barium sulfate in 50 parts ethanol-water solution (40 parts deionized water and 10 parts anhydrous ethanol), add 0.6 parts water glass, stir for 15 min, adjust the pH value to 9 with 0.5 wt% ammonia water, react at 50℃ for 30 min, filter, wash with deionized water, and vacuum dry at 70℃ to obtain modified matting agent G.

[0094] Example 1

[0095] Preparation of matte varnish:

[0096] Add 50 parts of waterborne acrylic resin and 2.5 parts of melamine-modified urea-formaldehyde resin to a dispersion vessel and start stirring (300 r / min). Mix 10 parts of modified matting agent A with 10 parts of water and pre-disperse for 5 min (800 r / min) using a high-speed disperser. Add the mixture to the dispersion vessel and mix with the waterborne acrylic resin. Continue stirring for 5 min (300 r / min). Add 0.05 parts of defoamer and 1.8 parts of film-forming aid sequentially and stir for 10 min (350 r / min). Mix 0.4 parts of thickener with 10 parts of water, pre-disperse for 5 min (300 r / min), and add the mixture to the dispersion vessel. Continue adding 0.15 parts of pH adjuster and 30 parts of water sequentially and stir for 5 min (450 r / min). Continue adding 0.1 parts of defoamer sequentially and stir for 20 min (300 r / min). Take a sample and test the viscosity, which is 65~70 KU, to obtain a matte varnish.

[0097] Example 2

[0098] Preparation of matte varnish:

[0099] It is largely the same as Example 1, except that modified matting agent A is replaced with modified matting agent B.

[0100] Example 3

[0101] Preparation of matte varnish:

[0102] It is largely the same as Example 1, except that modified matting agent A is replaced with modified matting agent C.

[0103] Example 4

[0104] Preparation of matte varnish:

[0105] It is largely the same as Example 1, except that modified matting agent A is replaced with modified matting agent D.

[0106] Example 5

[0107] Preparation of matte varnish:

[0108] It is largely the same as Example 1, except that modified matting agent A is replaced with modified matting agent E.

[0109] Comparative Example 1

[0110] Preparation of matte varnish:

[0111] It is largely the same as Example 1, except that modified matting agent A is replaced with modified matting agent F.

[0112] Comparative Example 2

[0113] Preparation of matte varnish:

[0114] It is largely the same as Example 1, except that modified matting agent A is replaced with modified matting agent G.

[0115] Comparative Example 3

[0116] Preparation of matte varnish:

[0117] Similar to Example 1, except that 10 parts of modified matting agent A were replaced with 9 parts of talc and 3 parts of barium sulfate.

[0118] Comparative Example 4

[0119] Preparation of matte varnish:

[0120] Add 52.5 parts of waterborne acrylic resin to a dispersion vessel and start stirring (300 rpm). Mix 10 parts of modified matting agent A with 10 parts of water and pre-disperse the mixture for 5 minutes (800 rpm) using a high-speed disperser. Add the mixture to the dispersion vessel and mix it with the waterborne acrylic resin. Continue stirring for 5 minutes (300 rpm). Add 0.05 parts of defoamer and 1.8 parts of film-forming aid in sequence and stir for 10 minutes (350 rpm). Mix 0.4 parts of thickener with 10 parts of water, pre-disperse the mixture for 5 minutes (300 rpm), and add it to the dispersion vessel. Continue adding 0.15 parts of pH adjuster and 30 parts of water in sequence and stir for 5 minutes (450 rpm). Continue adding 0.1 parts of defoamer in sequence and stir for 20 minutes (300 rpm). By finely adjusting the amount of water, the viscosity of the sample test is made to be 65~70 KU, thus obtaining a matte varnish.

[0121] Comparative Example 5

[0122] Preparation of matte varnish:

[0123] Add 45 parts of waterborne acrylic resin and 7.5 parts of melamine-modified urea-formaldehyde resin to a dispersion vessel and start stirring (300 r / min). Mix 10 parts of modified matting agent A with 10 parts of water and pre-disperse for 5 min using a high-speed disperser (800 r / min). Add the mixture to the dispersion vessel and mix with the waterborne acrylic resin. Continue stirring for 5 min (300 r / min). Add 0.05 parts of defoamer and 1.8 parts of film-forming aid sequentially and stir for 10 min (350 r / min). Mix 0.4 parts of thickener with 10 parts of water, pre-disperse for 5 min (300 r / min), and add the mixture to the dispersion vessel. Continue adding 0.15 parts of pH adjuster and 30 parts of water sequentially and stir for 5 min (450 r / min). Continue adding 0.1 parts of defoamer sequentially and stir for 20 min (300 r / min). By finely adjusting the water amount, take a sample and test the viscosity to obtain 65~70 KU, thus obtaining a matte varnish.

[0124] Test section

[0125] The matte varnishes prepared in the examples and comparative examples were subjected to performance tests.

[0126] Gloss test: 3 mL of paint was placed on one end of a degreased glass plate, and a paint film applicator was used to spread the paint at a speed of 100 mm / s to form a smooth paint film. After drying at 110℃ for 40 min, the plate was allowed to stand for 24 h at 25℃ and 50% relative humidity to obtain the test sample. Referring to the national standard GB / T9754-2007, a gloss meter was used to measure the gloss value when the axis of the incident beam made an 85° angle with the normal to the test surface.

[0127] Abrasion resistance test: 3 mL of paint was placed on one end of an asbestos-free fiber cement plate, and a paint film applicator was used to scrape the paint film at a speed of 100 mm / s to form a smooth paint film. After drying at 110℃ for 40 min, the plate was left to stand at 25℃ and 50% relative humidity for 24 h to obtain the test sample. Referring to the national standard GB / T1768-2006, the mass m1 of the test sample was weighed. After running the plate 500 times with a 1 kg load on a rubber grinding wheel, the loose abrasion debris was removed, and the mass m2 of the test sample was weighed again. The abrasion loss Δm = m1 - m2 was calculated.

[0128] The test results are shown in Table 1.

[0129] Table 1

[0130]

[0131] As shown in Table 1, the matte varnishes obtained in each embodiment have lower gloss and higher abrasion resistance compared to the comparative examples. This may be because the matting agent in Comparative Example 1 only introduces a sodium lignin sulfonate coating layer on the surface of inorganic particles, lacking the secondary-scale structural features provided by the silicon-oxygen structure. This limits the multi-level scattering of incident light, and the matting interface structure may be easily weakened during wear, resulting in higher gloss. In Comparative Example 2, only water glass modification is used, and the resulting silicon-oxygen structure may easily agglomerate, which is not conducive to forming a continuous scattering interface distribution on the coating surface. Furthermore, the lack of a lignin layer for toughness buffering makes the silicon-oxygen structure prone to detachment during wear. In Comparative Example 3, unmodified talc and barium sulfate are directly used as matting fillers, and their matting effect mainly relies on single-scale inorganic particles. The physical roughness effect formed on the coating surface lacks a multi-scale synergistic scattering system jointly constructed by the organic coating layer and the silicon-oxygen structure. During the wear process, the rough structure of the coating surface is easily weakened, resulting in limitations on the matting effect and its retention. In Comparative Example 4, the amount of waterborne acrylic resin was increased, but the micro-crosslinking structure formed by melamine-modified urea-formaldehyde resin was lacking, thus missing the role in controlling the scale distribution of the matting structure and the optical interface. The gloss was still relatively high. In Comparative Example 5, the amount of melamine-modified urea-formaldehyde resin was too high, which easily formed a micro-crosslinking aggregate structure with a large scale during the film formation process. This may interfere with the reasonable distribution and synergistic effect of the matting structure. The high local rigidity may also make the surface microstructure more prone to brittle failure or particle peeling during the wear process, which is not conducive to maintaining wear resistance.

[0132] As can be seen from Examples 1-4, fumed silica has a certain influence on the performance of matte varnish. When the mass ratio of decolorized sodium lignosulfonate to fumed silica is 1:0.2-0.35, the matte varnish has better matteness and abrasion resistance.

[0133] As can be seen from Examples 1 and 5, γ-aminopropyltriethoxysilane has a certain influence on the performance of matte varnish. When a certain mass of γ-aminopropyltriethoxysilane is added, the matte varnish has better matteness and abrasion resistance.

[0134] 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 matte varnish, characterized in that, Includes the following quantities of raw materials: The ingredients are: 50 parts water-based acrylic resin, 5-15 parts modified matting agent, 0.05-0.2 parts defoamer, 1-2 parts film-forming aid, 0.2-1 part thickener, 0.1-0.2 parts pH adjuster, and 40-60 parts water. The modified matting agent is prepared through the following steps: S1: Disperse talc, barium sulfate, and decolorizing sodium lignin sulfonate in water, so that the decolorizing sodium lignin sulfonate undergoes physical adsorption and interfacial interaction with the surface of inorganic particles to form a sodium lignin sulfonate layer coated on the surface of the inorganic matrix, thus obtaining a matting agent coated with sodium lignin sulfonate. S2: Disperse the lignosulfonate-coated matting agent and water glass in an ethanol-water solution, so that the water glass forms a silicon-oxygen structure and is deposited in situ on the surface of the lignosulfonate coating layer to obtain the modified matting agent. The decolorized sodium lignin sulfonate is prepared by the following steps: Sodium lignosulfonate and hydrogen peroxide were dispersed in water for decolorization treatment. Disodium ethylenediaminetetraacetate was added to cause the metal ion impurities in sodium lignosulfonate to complex with disodium ethylenediaminetetraacetate, thus obtaining decolorized sodium lignosulfonate. The talc powder has an average flake size of 1~10μm, and the barium sulfate has an average particle size of 50~200nm; The raw materials also include melamine-modified urea-formaldehyde resin, wherein the mass ratio of the water-based acrylic resin to the melamine-modified urea-formaldehyde resin is 1:0.04~0.

06.

2. The matte varnish according to claim 1, characterized in that, The decolorized sodium lignin sulfonate described in step S1 is prepared through the following steps: Disperse 10 parts of sodium lignosulfonate and 1-10 parts of 3wt%-10wt% hydrogen peroxide in 10-50 parts of water, adjust the pH to 8-9, react at 40-60℃ for 10-60 min, add 0.1-0.3 parts of disodium ethylenediaminetetraacetate, and react at 40-60℃ for 10-60 min to obtain decolorized sodium lignosulfonate.

3. The matte varnish according to claim 1, characterized in that, In step S1, fumed silica is also added, wherein the mass ratio of the decolorized sodium lignosulfonate to fumed silica is 1:0.2~0.

35.

4. The matte varnish according to claim 3, characterized in that, In step S2, a silane coupling agent is also added, including γ-aminopropyltriethoxysilane, and the mass ratio of the silane coupling agent to the matting agent coated with sodium lignosulfonate is 0.05~0.2:

10.

5. The matte varnish according to claim 4, characterized in that, The modified matting agent is prepared through the following steps: S1: Disperse 1 part of decolorizing sodium lignosulfonate, 0.2~0.35 parts of fumed silica, 10~50 parts of talc powder, and 5~30 parts of barium sulfate in 10~100 parts of water, and react at 40~60℃ for 10~60 min to obtain a matting agent coated with sodium lignosulfonate. S2: Disperse 10 parts of sodium lignosulfonate-coated matting agent, 0.2-0.8 parts of water glass, and 0.05-0.2 parts of γ-aminopropyltriethoxysilane in 10-50 parts of ethanol-water solution, adjust the pH to 8.5-9.5, and react at 40-60℃ for 10-60 min to obtain the modified matting agent.

6. The matte varnish according to any one of claims 3 to 5, characterized in that, The matte varnish satisfies at least one of the following conditions: 1) The defoamer includes mineral oil-based defoamers; 2) The film-forming aids include ester-based film-forming aids; 3) The thickener includes acrylic thickeners; 4) The pH adjuster includes organic amine pH adjusters; 5) The average particle size of the fumed silica is 1~20nm.

7. A method for preparing matte varnish, characterized in that, include: Provide the raw materials included in the matte varnish according to any one of claims 1 to 6; The raw materials are blended to obtain a matte varnish.

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