Solvent-free anti-doodling cover agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of coatings, in particular to a solvent-free anti-doodling cover agent as well as a preparation method and application thereof. The solvent-free anti-doodling finishing agent is prepared from the following raw materials in percentage by mass: 80 to 95 weight percent of solvent-free methyl phenyl silicone resin, 1 to 5 weight percent of a curing agent, 3 to 8 weight percent of an adhesion enhancer, 0.5 to 3 weight percent of an anti-doodling auxiliary agent and 0 to 6 weight percent of an optional delustering agent. The core is that the adhesion enhancer is an enhanced silane coupling agent and is prepared by carrying out molecular-level chemical bonding on a titanium compound, the silane coupling agent and a self-made antifouling agent. The finishing agent disclosed by the invention has the advantages of high adhesive force, excellent stain resistance, adjustable glossiness and the like, and is suitable for base material protection of various scenes such as building outer walls, household crystal plating and artistic coatings.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a solvent-free anti-graffiti finisher and its preparation method and application. BACKGROUND

[0002] As the final protective layer of the coating system, the finish directly determines the durability, decoration and anti-graffiti of the coating. The traditional water-based finish has poor wear resistance and almost zero anti-graffiti, and ordinary pencils and wax pencils cannot be wiped clean. Although the solvent-based finish has acceptable performance, it contains a large amount of volatile organic compounds (VOC), which is harmful to the environment and human health. With the increasingly stringent environmental regulations, the development of solvent-free high-performance finish has become an urgent need in the industry. However, the simple removal of solvents will lead to increased viscosity and poor stability of the system, and higher challenges to the adhesion to the substrate and long-term anti-graffiti performance.

[0003] Most existing solvent-free finishes use silicone resin as the matrix to achieve anti-graffiti function by its low surface energy, but have inherent limitations: on the one hand, the adhesion of silicone resin to inorganic substrates (such as stone and metal) is generally weak, and needs to rely on silane coupling agents for improvement; on the other hand, the traditional physical blending of silane coupling agents has single function and only plays the role of adhesion bridge, cannot participate in the crosslinking of the system, and has no inhibitory effect on the migration and loss of small molecule anti-graffiti additives, leading to rapid decay of anti-graffiti performance. In addition, a single formula cannot meet the diversified decoration needs of high gloss and matte finish.

[0004] Although some research has tried to add titanate catalyst or composite silane to improve performance, it is still at the stage of physical blending, and there is a lack of molecular-level synergy between components, which is prone to phase separation or function offset. How to solve the key problems of adhesion, long-term anti-graffiti and gloss control simultaneously without introducing solvents is still a technical bottleneck that needs to be broken through in the field. Therefore, it is of great significance to develop a solvent-free finish that has both environmental protection and comprehensive performance to promote the upgrading of the industry. SUMMARY

[0005] In view of the above problems in the prior art, the present application provides a solvent-free anti-graffiti finisher and its preparation method and application.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0007] A solvent-free anti-graffiti finisher, which is composed of the following raw materials in mass percentage:

[0008] 80wt%-95wt% of solvent-free methylphenyl silicone resin,

[0009] 1wt%-5wt% of curing agent,

[0010] adhesion enhancer 3wt%-8wt%,

[0011] anti-graffiti aid 0.5wt%-3wt%,

[0012] and optionally matting agent 0wt%-6wt%.

[0013] Preferably, when the finish is gloss, it contains no matting agent; when the finish is matte, it contains 3wt%-6wt% of matting agent.

[0014] Preferably, the curing agent is selected from one or more of titanate, isocyanate, amino resin;

[0015] The adhesion enhancer is an enhanced silane coupling agent; the anti-graffiti aid is selected from one or more of hydroxyl silicone oil, amino silicone oil, hydrogen-containing silicone oil; the matting agent is hydrophobic fumed silica.

[0016] The present application directly adds ordinary silane coupling agent, which can improve the adhesion to a certain extent, but it has multiple inherent defects. First, its function is single, only as a physical bonding bridge, cannot actively participate in and optimize the crosslinking network of the system, the adhesion improvement is not large. Secondly, in terms of anti-graffiti, it itself does not have anti-graffiti function, and cannot improve the problems of easy migration and easy precipitation of small molecule anti-graffiti aid, and even may exacerbate the loss of the aid due to compatibility problems, leading to rapid decay of anti-graffiti performance.

[0017] The addition of enhanced silane coupling agent can effectively overcome the defects of the above-mentioned ordinary silane coupling agent. In terms of adhesion, the enhanced silane coupling agent couples titanium compounds and silane through the reaction between substances. It is not only a bonding bridge, but also can catalyze the crosslinking reaction between itself and the substrate, and itself and the resin in situ, forming a solid transition layer with higher crosslinking density at the interface, realizing the leap from direct physical coating to chemical welding, and thus obtaining adhesion strength and durability far exceeding ordinary silane; In terms of anti-graffiti durability, the key lies in the chemical integration of anti-graffiti components into the molecular chain through covalent bond, and the fixation of anti-graffiti components in the network through chemical bond, avoiding the problem of failure of physical blending small molecules due to rapid migration and precipitation. It can slowly release and continuously supplement the surface anti-graffiti layer with the action of the environment, even if the surface is worn, the internal can still continuously act, thus realizing long-acting anti-graffiti ability; In terms of gloss control, its larger molecular structure and excellent compatibility improve the stability of the system, more importantly, its built-in titanium catalyst can promote the formation of a more uniform and stable crosslinking structure of the whole system. This structure can effectively lock the matting agent particles, prevent them from flocculating or settling, and ensure the uniformity and stability of the gloss of matte products, realizing precise control of the final appearance.

[0018] Preferably, the adhesion enhancer is an enhanced silane coupling agent, which is prepared by a method comprising the following steps: mixing and reacting a titanium compound, a silane coupling agent, an antifouling agent and an organic solvent, and removing the organic solvent after the reaction to obtain the enhanced silane coupling agent.

[0019] Preferably, the titanium compound is titanium diamino tetrachloride; the antifouling agent is prepared by reacting an alcohol amine compound with an acrylate compound in an alcohol solvent.

[0020] Preferably, the silane coupling agent is selected from at least one of silane coupling agents containing amino and carboxyl groups.

[0021] Further, the silane coupling agent is at least one or two of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, N-[β-(N,N-diacetate aminoethyl)-γ-(N-acetate amino propyl) trimethoxysilane, acrylamide propyl trimethoxysilane, allyl triethoxysilane; further, the silane coupling agent is 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, N-[β-(N,N-diacetate aminoethyl)-γ-(N-acetate amino propyl) trimethoxysilane is compounded in a mass ratio of 1: (1-3).

[0022] The reaction mechanism of the enhanced silane coupling agent is as follows: the titanium (IV) center coordinates with the hydroxyl group and the amido oxygen atom in the antifouling agent molecule to form a chelate ring, the titanium (IV) center coordinates and / or ionically bonds with the carboxyl group in the carboxyl-containing silane coupling agent (such as N-[β-(N,N-diacetate aminoethyl)-γ-(N-acetate amino propyl) trimethoxysilane), and under the reaction conditions, a titanium-oxygen bond may be partially formed, the titanium (IV) center coordinates with the amino group in the amino-containing silane coupling agent (such as 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane); at the same time, the titanium (IV) center strongly coordinates and / or ionically bonds with the carboxyl group on the carboxylated silane coupling agent; if the silane coupling agent used contains an amino group or other electron-donating functional groups, it can also coordinate with the titanium center to form a multi-nuclear hybrid structure centered on titanium, thereby significantly improving the stability and durability of the coating.

[0023] Preferably, the preparation method of the enhanced silane coupling agent is as follows: comprising the following steps: under an inert atmosphere, 6-12 parts by weight of titanium compound, 12-20 parts by weight of silane coupling agent, 3-8 parts by weight of antifouling agent and 200-400 parts by weight of organic solvent are uniformly mixed, stirred and reacted at 60-80℃ for 2-6h, and then the organic solvent is removed by reduced pressure distillation to obtain the enhanced silane coupling agent.

[0024] The reaction mechanism of the antifouling agent: The amino group in diethanolamine undergoes a Michael addition reaction with butyl acrylate. The secondary amino group in the diethanolamine molecule acts as a nucleophilic center, launching a nucleophilic attack on the β-carbon atom in the acryloyl group of butyl acrylate, which is activated by the conjugation effect, resulting in a Michael addition reaction and ultimately forming a CN bond. The antifouling agent molecule in this invention also contains polydentate coordinating groups such as hydroxyl and amide groups, which can coordinate or covalently bond with titanium compounds and carboxyl / amino silanes, participating in the crosslinking network of reinforced silane coupling agents and silicone resins. This avoids the easy migration and loss of ordinary small molecule additives, and continuously exerts antifouling effects inside the paint film and at the interface. At the same time, these chemically fixed antifouling groups selectively accumulate on the coating surface during film formation, synergistically reducing surface energy with organosilicon resins and silicone oil-based antigraffiti additives, making it difficult for water and stains to wet and adhere, and easy to clean, thus achieving long-lasting antigraffiti effect.

[0025] Preferably, the antifouling agent is prepared by the following method: 6-10 parts by weight of diethanolamine, 8-16 parts by weight of butyl acrylate and 100-180 parts by weight of anhydrous ethanol are mixed evenly, stirred and reacted at 50-70°C for 1-5 hours, and then the ethanol is removed by vacuum distillation to obtain the antifouling agent.

[0026] The preparation method of the solvent-free anti-graffiti topcoat includes the following steps: mixing the solvent-free methylphenyl silicone resin, curing agent, adhesion enhancer, anti-graffiti additive and optional matting agent in the specified mass percentages, and stirring at high speed until uniform to obtain the topcoat.

[0027] A method for anti-graffiti treatment of a substrate includes the steps of applying the solvent-free anti-graffiti topcoat agent described above to the surface of the substrate and allowing it to cure.

[0028] The roles of each substance in this invention:

[0029] Solvent-free methylphenyl silicone resin: As the matrix resin of the system, it forms the skeleton and continuous phase of the paint film. Its role is to provide excellent weather resistance, low surface energy for anti-graffiti properties, and ensure environmental safety. The organosilicon backbone endows the coating with extremely strong UV resistance, high and low temperature resistance, and is not prone to yellowing or chalking, with a lifespan far exceeding that of ordinary organic resins. Simultaneously, its inherent low surface energy produces excellent hydrophobic effects, making it difficult for water and water-borne contaminants to adhere. Methyl groups provide hydrophobicity and flexibility, while phenyl groups enhance heat resistance, hardness, and compatibility with other components. Furthermore, the solvent-free nature essentially eliminates VOC emissions, meeting environmental protection requirements and ensuring construction safety.

[0030] Hardener: The crosslinking engine of the system, its core role is to chemically react with the active groups of silicone resin, transforming the liquid coating into a robust solid film. This crosslinking process is crucial, significantly improving the final properties of the film, including hardness, abrasion resistance, chemical resistance, and anti-blocking properties. Without a hardener, the coating will not achieve sufficient mechanical strength and service durability.

[0031] Adhesion enhancers: acting as molecular bridges between the coating and the substrate, their core function is to solve the key problem of insufficient adhesion of high-performance silicone coatings on inorganic substrates. Ordinary silane coupling agents achieve this function through their amphiphilic structure: the hydrolyzable group at one end forms a strong Si-O-Si covalent bond with the substrate; the organic functional group at the other end chemically bonds or physically entangles with the resin system.

[0032] Anti-graffiti additives are functional modifiers for the paint film surface. Their core function is to migrate to the coating surface, forming a dynamic, extremely low surface energy protective layer, thereby enhancing and maintaining the anti-graffiti performance of the system. Different types of silicone oils have their own characteristics: hydroxyl silicone oils improve the feel and contribute hydrophobicity; amino silicone oils, due to their polarity, can be oriented, providing more durable hydrophobic and oleophobic properties; hydrogen-containing silicone oils can crosslink under the action of a catalyst, forming a stronger and more durable anti-graffiti layer. Their compatibility with silicone resins, but not complete compatibility, ensures that they can migrate slowly and continuously to the surface. Even if the surface layer fails due to wear or aging, the internal additives can be replenished in time, thus overcoming the defects of small molecule additives being easily lost and having a short anti-graffiti lifespan.

[0033] Matting agents are optical property modifiers in a system. They reduce surface gloss and achieve a matte or satin finish by creating microscopic roughness in the paint film to scatter light. This formulation uses hydrophobic fumed silica, which, after surface treatment, exhibits good compatibility with solvent-free silicone resin systems and can be uniformly dispersed to form a large number of micron / nanometer-scale scattering points. This not only meets the diverse aesthetic demands of the market but also greatly improves production efficiency and the versatility of the formulation.

[0034] This formulation system achieves its goals through the interaction of its components. The resin and curing agent crosslink to form a robust paint film framework, laying the foundation for weather resistance and mechanical properties. The enhanced silane coupling agent acts as a core bridge, chemically bonding the substrate and resin network at both ends, fundamentally solving adhesion problems. Simultaneously, its built-in anti-fouling and catalytic components work in synergy with the system. Anti-graffiti additives dynamically migrate to the surface, working synergistically with the resin's inherent low surface energy and the coupling agent's anti-fouling function. The matting agent precisely controls gloss without compromising system compatibility. The entire system achieves integrated synergy from interfacial adhesion, overcoming the problems of poor adhesion, short-lasting anti-graffiti performance, and limited functionality inherent in traditional products.

[0035] The beneficial effects of this invention are:

[0036] This invention provides a solvent-free anti-graffiti topcoat, its preparation method, and its application. By employing an enhanced silane coupling agent, a breakthrough improvement in coating performance is successfully achieved. This component chemically bonds titanium compounds, silane coupling agents, and antifouling agents into a single structure. The titanium center provides a powerful catalytic cross-linking function, significantly enhancing interfacial adhesion and forming a dense paint film network. The chemically bonded antifouling agent establishes a durable antifouling mechanism, effectively solving the technical problem of easy migration and loss of traditional physically blended antifouling agents. This molecular-level functional integration enables the product to maintain its solvent-free and environmentally friendly characteristics while achieving beneficial properties such as Grade 0 adhesion, stain resistance, and water resistance.

[0037] 2. The topcoat system of this invention exhibits excellent applicability and stability. By adjusting the amount of matting agent added, a series of products ranging from high gloss to matte can be flexibly prepared on the same technical platform to meet the decorative needs of different application scenarios. The titanium catalyst in the enhanced silane coupling agent effectively stabilizes the matting agent dispersion system, prevents particle flocculation and sedimentation, and ensures the uniformity and stability of the gloss of matte products. This invention successfully overcomes common industry problems such as insufficient adhesion, rapid decay of anti-graffiti performance, and limited functionality of traditional topcoats, providing a comprehensive and environmentally friendly protective solution with excellent performance for building exterior walls, home ceramic coatings, and artistic coatings. Detailed Implementation

[0038] The invention will now be described in further detail with reference to specific embodiments, but it should not be construed as limiting the scope of the invention to the following embodiments.

[0039] The raw materials described in this application are partially described; all other raw materials not described are commercially available.

[0040] The solvent-free methylphenyl silicone resin was purchased from Hubei Longsheng Sihai New Materials Co., Ltd., grade: SH-3047.

[0041] The hydrophobic fumed silica was purchased from Shanghai Zhenlishi Network Technology Co., Ltd., model number: TS620.

[0042] The hydroxyl silicone oil was purchased from Shandong Juneng Chemical Co., Ltd., model: JN-204.

[0043] Example 1

[0044] A solvent-free anti-graffiti topcoat, wherein when the topcoat is glossy, it is composed of the following raw materials in weight percentage: 92wt% solvent-free methylphenyl silicone resin, 2wt% curing agent, 5wt% adhesion enhancer, and 1wt% anti-graffiti additive.

[0045] The curing agent is tetrabutyl titanate.

[0046] The adhesion enhancer is a reinforced silane coupling agent.

[0047] The anti-graffiti additive is hydroxy silicone oil.

[0048] The adhesion enhancer is a reinforced silane coupling agent, and the preparation method of the reinforced silane coupling agent is as follows:

[0049] Under nitrogen atmosphere, 9 parts by weight of diammonium tetrachloride, 15 parts by weight of silane coupling agent, 6 parts by weight of antifouling agent and 300 parts by weight of DMF are mixed evenly and added to a sealed stirred reactor. The mixture is stirred at 70°C and 400 rpm for 5 hours. DMF is removed by vacuum distillation to obtain the enhanced silane coupling agent.

[0050] The antifouling agent is prepared by the following method: 8 parts by weight of diethanolamine, 12 parts by weight of butyl acrylate and 120 parts by weight of anhydrous ethanol are mixed evenly and stirred at 60°C and 200 rpm for 2.5 h. The ethanol is removed by vacuum distillation to obtain the antifouling agent.

[0051] The silane coupling agent is a mixture of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and N-[β-(N,N-diacetyl)aminoethyl]-γ-(N-acetyl)aminopropyltrimethoxysilane in a mass ratio of 1:2.

[0052] The preparation method of the solvent-free anti-graffiti topcoat is as follows: Mix solvent-free methylphenyl silicone resin, curing agent, adhesion enhancer and anti-graffiti additive, and stir at 800 rpm for 30 min to obtain the solvent-free anti-graffiti topcoat.

[0053] Example 2

[0054] The method is basically the same as Example 1, except that the silane coupling agent used in the preparation method of the enhanced silane coupling agent is 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane.

[0055] Example 3

[0056] The method is basically the same as Example 1, except that the silane coupling agent in the preparation method of the enhanced silane coupling agent is N-[β-(N,N-diacetyl)aminoethyl]-γ-(N-acetyl)aminopropyltrimethoxysilane.

[0057] Example 4

[0058] The process is basically the same as in Example 1, except that when the topcoat is matte, a matting agent is added to the raw materials of the solvent-free anti-graffiti topcoat, which consists of the following raw materials by mass percentage: 88wt% solvent-free methylphenyl silicone resin, 2wt% curing agent, 5wt% adhesion enhancer, 1wt% anti-graffiti additive, and 4wt% matting agent.

[0059] The curing agent is the same as that used in Example 1.

[0060] The anti-graffiti additive is the same as in Example 1.

[0061] The matting agent is hydrophobic fumed silica.

[0062] The adhesion enhancer is the same as in Example 1.

[0063] Comparative Example 1

[0064] A solvent-free anti-graffiti topcoat, wherein when the topcoat is glossy, it is composed of the following raw materials in weight percentage: 92wt% solvent-free methylphenyl silicone resin, 2wt% curing agent, 5wt% adhesion enhancer, and 1wt% anti-graffiti additive.

[0065] The curing agent is tetrabutyl titanate.

[0066] The adhesion enhancer is a reinforced silane coupling agent.

[0067] The anti-graffiti additive is hydroxy silicone oil.

[0068] The adhesion enhancer is a reinforced silane coupling agent, and the preparation method of the reinforced silane coupling agent is as follows:

[0069] Under nitrogen atmosphere, 9 parts by weight of diammonium tetrachloride, 15 parts by weight of silane coupling agent, 6 parts by weight of antifouling agent and 300 parts by weight of DMF are mixed evenly and added to a sealed stirred reactor. The mixture is stirred at 70°C and 400 rpm for 5 hours. DMF is removed by vacuum distillation to obtain the enhanced silane coupling agent.

[0070] The antifouling agent is prepared by the following method: 8 parts by weight of diethanolamine, 12 parts by weight of butyl acrylate and 120 parts by weight of anhydrous ethanol are mixed evenly and stirred at 60°C and 200 rpm for 2.5 h. The ethanol is removed by vacuum distillation to obtain the antifouling agent.

[0071] The silane coupling agent is a mixture of octyltriethoxysilane and N-[β-(N,N-diacetyl)aminoethyl]-γ-(N-acetyl)aminopropyltrimethoxysilane in a mass ratio of 1:2.

[0072] The preparation method of the solvent-free anti-graffiti coating agent is the same as that in Example 1.

[0073] Comparative Example 2

[0074] The process is basically the same as in Example 1, except that the solvent-free anti-graffiti topcoat is composed of the following raw materials in glossy form: 92 wt% solvent-free methylphenyl silicone resin, 2 wt% curing agent, 5 wt% adhesion enhancer, and 1 wt% anti-graffiti additive.

[0075] The adhesion enhancer is not a chemically bonded reinforcing silane coupling agent, but rather a physical mixture of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and N-[β-(N,N-diacetyl)aminoethyl]-γ-(N-acetyl)aminopropyltrimethoxysilane in a mass ratio of 1:2, which is then used directly as an adhesion enhancer.

[0076] The curing agent is the same as that used in Example 1.

[0077] The anti-graffiti additive is the same as in Example 1.

[0078] The preparation method of the solvent-free anti-graffiti coating agent is the same as that in Example 1.

[0079] Comparative Example 3

[0080] The method is basically the same as in Example 1, except that the titanium compound diammonium tetrachloride in the preparation method of the enhanced silane coupling agent is replaced with titanium dichlorodicenocene.

[0081] Comparative Example 4

[0082] It is basically the same as Example 1, except that the adhesion enhancer is a reinforced silane coupling agent.

[0083] The preparation method of the enhanced silane coupling agent is as follows:

[0084] Under nitrogen atmosphere, 9 parts by weight of diammonium tetrachloride, 15 parts by weight of silane coupling agent and 300 parts by weight of DMF were mixed evenly and added to a sealed stirred reactor. The mixture was stirred and reacted at 70°C and 400 rpm for 5 hours. DMF was removed by vacuum distillation to obtain the enhanced silane coupling agent.

[0085] The silane coupling agent is a mixture of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and N-[β-(N,N-diacetyl)aminoethyl]-γ-(N-acetyl)aminopropyltrimethoxysilane in a mass ratio of 1:2.

[0086] Comparative Example 5

[0087] The process is basically the same as in Example 1, except that the antifouling agent is prepared by the following method: 8 parts by weight of 2-amino-2-methyl-1-propanol, 12 parts by weight of butyl acrylate and 120 parts by weight of anhydrous ethanol are mixed evenly and stirred at 60°C and 200 rpm for 2.5 h. The ethanol is removed by vacuum distillation to obtain the antifouling agent.

[0088] Test Example 1

[0089] Performance index determination: Referring to the industry standard HG / T 5065-2016 "Topcoat Varnish for Architectural Coatings", the solvent-free anti-graffiti topcoat prepared in the above examples and comparative examples were tested. The stain resistance was tested using black marker, colored pen and cement paste as the staining medium to evaluate the residual rate after cleaning. Each set of data can be tested 4 times and the average value is taken. The results are shown in Table 1.

[0090] Table 1 Performance Index Measurement Results

[0091] The results above show that the solvent-free anti-graffiti topcoat prepared by this invention has good gloss, stain resistance, water resistance, and adhesion. Specifically, as shown in Examples 1-3, Example 1 uses a combination of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and N-[β-(N,N-diacetyl)aminoethyl]-γ-(N-acetyl)aminopropyltrimethoxysilane as a coupling agent. The technical effect is significantly better than that of Examples 2 and 3 using any one of these coupling agents. This is because the bisaminosilane, through coordination bonds, and the carboxylic acid silane, through covalent / ionic bonds, firmly fix the silane molecules around the titanium center through two different chemical forces, forming an exceptionally stable structure. Therefore, the adhesion, water resistance, and durability are all superior to those using a single silane. Furthermore, as can be seen from Examples 1 and 1 Comparative Example, Example 1 uses a highly active amino / carboxylsilane, which can form strong coordination and covalent bonds with the titanium center to create a more stable hybrid interface layer. In contrast, Comparative Example 1 uses an inert octylsilane, whose alkyl chains cannot chemically interact with the titanium center, resulting in the failure of the interface bridging function. This not only causes a sharp drop in adhesion but also damages the overall cross-linking network, leading to a decline in stain resistance / graffiti resistance and water resistance. When Comparative Example 2 uses a physically mixed silane, the components are independent of each other and cannot construct a stable hybrid structure centered on titanium. It lacks both interfacial catalytic cross-linking function and, due to the easy loss of anti-graffiti additives, cannot achieve a durable stain resistance / graffiti effect, resulting in a comprehensive decline in overall performance. Comparative Example 3 uses titanium dichlorodicyclopentadiene, whose stable cyclopentadiene structure and chloride ions make it difficult to react with the silane in this system as expected, failing to form an effective molecular bridging structure, resulting in the failure of the interface strengthening function and a significant decrease in performance. In particular, Comparative Example 4, lacking a chemically bonded antifouling agent and relying solely on physically blended additives, experiences rapid migration and loss, leading to a sharp decline in stain resistance / graffiti resistance. Comparative Example 5 uses 2-amino-2-methyl-1-propanol, which has high steric hindrance and few coordination sites, resulting in poor chelation stability with titanium, leading to a decrease in the slow-release efficiency of the antifouling agent and a significant reduction in stain resistance. Furthermore, a comparison between Examples 1 and 4 shows that adhesion and stain resistance are reduced, while water resistance remains excellent. By introducing 4 wt% of a hydrophobic fumed silica matting agent, the 60° gloss level can be significantly reduced, achieving an adjustable appearance from high gloss to matte. However, the comparative examples did not simultaneously achieve both the above-mentioned performance and gloss control.

Claims

1. A solvent-free type anti-graffiti overcoat characterized by comprising: consists of the following raw materials in percentage by mass: a solvent-free methylphenyl silicone resin 80wt%-95wt%, a curing agent 1wt%-5wt%, an adhesion enhancer 3wt%-8wt%, an anti-graffiti aid 0.5wt%-3wt%, and optionally a matting agent 0wt%-6wt%; the adhesion enhancer is an enhanced silane coupling agent; the enhanced silane coupling agent is prepared by mixing and reacting a titanium compound, a silane coupling agent, an anti-fouling agent and an organic solvent, and removing the organic solvent after the reaction.

2. The solvent-free anti-graffiti overcoat of claim 1, wherein, when the finish is a glossy type, it does not contain a matting agent; when the finish is a matte type, it contains 3wt%-6wt% of a matting agent.

3. The solvent-free anti-graffiti overcoat of claim 1, wherein, the curing agent is selected from one or more of titanate, isocyanate, amino resin; the anti-graffiti aid is selected from one or more of hydroxyl silicone oil, amino silicone oil, hydrogen-containing silicone oil; the matting agent is a hydrophobic fumed silica.

4. The solvent-free anti-graffiti overcoat of claim 1, wherein, the titanium compound is titanium diamine tetrachloride; the anti-fouling agent is prepared by reacting an alcohol amine compound with an acrylate compound in an alcohol solvent.

5. The solvent-free anti-graffiti overcoat of claim 1, wherein, the silane coupling agent is selected from at least one of silane coupling agents containing amino and carboxyl groups.

6. The solvent-free anti-graffiti overcoat of claim 1, wherein, the preparation method of the enhanced silane coupling agent is as follows: under an inert atmosphere, 6-12 parts by weight of a titanium compound, 12-20 parts by weight of a silane coupling agent, 3-8 parts by weight of an anti-fouling agent and 200-400 parts by weight of an organic solvent are mixed uniformly, stirred and reacted at 60-80℃ for 2-6h, and then the organic solvent is removed by reduced pressure distillation to obtain the enhanced silane coupling agent.

7. The solvent-free anti-graffiti overcoat of claim 6, wherein, the anti-fouling agent is prepared by the following method: 6-10 parts by weight of diethanolamine, 8-16 parts by weight of butyl acrylate and 100-180 parts by weight of anhydrous ethanol are mixed uniformly, stirred and reacted at 50-70℃ for 1-5h, and then ethanol is removed by reduced pressure distillation to obtain the anti-fouling agent.

8. The process for the preparation of a solvent-free anti-graffiti overcoat according to any one of claims 1 to 7, characterized in that, comprises the following steps: the solvent-free methylphenyl silicone resin, the curing agent, the adhesion enhancer, the anti-graffiti aid and the optional matting agent are mixed and stirred at high speed until uniform, to obtain the finish.

9. A method for anti-graffiti treatment of a substrate, characterized in that comprises the steps of coating the solvent-free anti-graffiti finish of any one of claims 1-7 on the surface of a substrate, and curing it.

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