A round-cornered rock plate with a color-corrected layer and a processing method thereof

Abstract

The present application relates to the technical field of rock plate, in particular to a kind of round corner rock plate with color layer and processing method thereof.The processing method includes the following steps: cutting and grading polishing to the edge corner of rock plate, forming in order bottom coating, color layer and UV curing transparent wear-resistant cover surface coating in round corner part;Cover surface coating contains the silicon dioxide coated cerium-zirconium composite oxide modified by γ-ureidopropyl triethoxysilane and acryloyloxypropyl trimethoxysilane.Complex.The round corner part obtained after UV curing, wet grinding and polishing is coordinated with the color and luster of rock plate body, and has good wear resistance, weather resistance and color stability.The present application adopts cold processing combined with multilayer color correction, avoids discoloration caused by hot bending, and is suitable for round corner processing of rock plate countertop and decorative plate.

Description

Technical Field

[0001] This invention relates to the field of sintered stone technology, specifically to a rounded corner sintered stone slab with a color-correcting layer and its processing method. Background Technology

[0002] Sintered stone slabs are characterized by their large size, high hardness, wear resistance, and rich decorative effects, and are widely used in furniture countertops, wall surfaces, cabinets, and architectural decoration. To avoid sharp edges and improve the product's appearance, the edges of sintered stone slabs are usually rounded. Existing rounded structures in sintered stone slabs are mainly formed through high-temperature hot bending, mold pressing, or mechanical cutting. The hot bending process requires softening the sintered stone at high temperatures before bonding it to the mold, resulting in complex equipment and mold structures. Furthermore, uneven heating, differences in thermal expansion between the slab and the glaze, and cooling stress can lead to color changes, curvature deviations, or surface defects. While mechanical cutting avoids overall high-temperature treatment, it exposes a substrate with a different color and gloss than the sintered stone's decorative surface. Therefore, the issues of color matching, wear resistance, and long-term weather resistance of the rounded cut surfaces still need to be addressed.

[0003] Chinese invention patent application CN114646218A discloses a hot bending furnace for slab rock and a method for hot bending slab rock. It employs a first heating device to heat the entire furnace cavity, and a movable second heating device to locally heat the portion of the slab rock to be bent. Rapid cooling with blowing air further bonds the slab rock to the mold. The disclosed process requires heating the furnace cavity to 1000-1100℃, with local heating temperatures reaching 1200-1300℃. While this patent improves the bonding between the hot-bent slab rock and the mold, it still relies on a high-temperature furnace, local heating devices, and a cooling system, resulting in a high process cycle and equipment requirements. Furthermore, under high-temperature heat treatment conditions, strict control of the slab rock's color and surface quality is still necessary.

[0004] Chinese invention patent application CN117445201A discloses a hot-working mold and method for cylindrical arc-shaped slabs. It utilizes a cylindrical support structure, positioning plate, arc track, and pressing rollers to position and press the softened slab, forming a cylindrical arc-shaped structure of 180°-360°. This patent primarily addresses the positioning and forming problems of large-arc cylindrical slabs; however, the mold structure and pressing mechanism are relatively complex, mainly suitable for hot bending of integral cylindrical arcs, and difficult to directly meet the low-cost processing needs of small-range rounded corners on the outer contour of tabletop slabs. Furthermore, it does not address the issue of color and gloss restoration between the rounded corners and the slab body after mechanical cutting.

[0005] Chinese invention patent application CN102408827A discloses a water-based UV-curable transparent primer and its preparation method. The primer is prepared using water-based UV resin, water-based UV abrasion-resistant resin, reactive diluent, talc, glass powder, fumed silica, and photoinitiator. It can be applied by spraying or roller coating and is used to improve the hardness, water resistance, and scratch resistance of the coating film. This patent mainly targets transparent primers for wood products and does not address the multi-layer color-correcting structure of rounded corner cut surfaces of slabs, nor does it solve the problems of agglomeration, light scattering, and long-term color difference changes in the color-correcting layer that may occur after inorganic functional particles are added to the transparent topcoat.

[0006] Therefore, existing technologies cannot simultaneously achieve low-temperature forming, color restoration, gloss coordination, transparent wear-resistant protection, and long-term weather resistance stability during the rounded corner processing of sintered stone slabs. Therefore, it is necessary to provide a rounded corner sintered stone slab with a color-correcting layer and its processing method. Summary of the Invention

[0007] To address the shortcomings of the existing technology, the present invention provides a rounded corner rock slab with a color-correcting layer and its processing method.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0009] A method for processing rounded corner slabs with a color-correcting layer includes the following steps:

[0010] (1) The intersection area of ​​the adjacent two sides of the rock slab body is cut and processed to form a rounded corner on the outer contour of the rock slab body. The rounded corner has an arc-shaped cutting surface extending along the thickness direction of the rock slab.

[0011] (2) Grind and polish the rounded corner to make the surface roughness Ra of the rounded corner 0.5-0.7μm;

[0012] (3) Clean the surface of the rounded corners;

[0013] (4) Apply a base coat and a colorant layer sequentially to the rounded corner surface;

[0014] A UV-curable transparent abrasion-resistant topcoat is coated on the surface of the pigment layer. The UV-curable transparent abrasion-resistant topcoat contains modified composite particles, which are cerium-zirconium composite oxides with silica surface modified by a silane coupling agent. The silane coupling agent is γ-ureopropyltriethoxysilane and / or acryloyloxypropyltrimethoxysilane. The UV-curable transparent abrasion-resistant topcoat also contains a UV absorber.

[0015] (5) The UV-curable transparent wear-resistant topcoat is subjected to UV curing treatment to cure the UV-curable transparent wear-resistant topcoat to form a topcoat coating.

[0016] This invention first uses mechanical cutting to create rounded corners on the outer contour of a slab, followed by graded grinding and polishing with sandpaper of different grits to gradually reduce cutting marks and control the surface roughness of the rounded corners within a suitable range. Subsequently, an epoxy resin base coating, a water-based acrylic color-correcting layer, and a UV-cured transparent wear-resistant topcoat are sequentially applied to the rounded corners. The base coating covers the micropores and uneven areas of the cut surface, the color layer compensates for color differences between the cut surface and the decorative surface of the slab, and the transparent topcoat seals and protects the color layer. After the topcoat has cured, wet grinding and polishing are performed to harmonize the gloss of the rounded corner area with the slab itself, thus solving the problem of inconsistency in color, gloss, and surface texture between the rounded corners and the slab body after mechanical cutting.

[0017] Preferably, the cutting process is performed using a diamond grinding wheel with a rotation speed of 3000-5000 rpm, and the feed speed of the rock slab body is 8-15 mm / s; the grinding and polishing process includes coarse grinding with 600-1000 grit sandpaper, fine grinding with 1000-1500 grit sandpaper, and polishing with 1800-2400 grit sandpaper in sequence.

[0018] Preferably, the base coating is formed by curing an epoxy resin system, and its dry film thickness is 5-15 μm; the colorant layer is formed by color-correcting paint, and its dry film thickness is 3-10 μm; the topcoat coating has a dry film thickness of 10-25 μm.

[0019] This invention employs a cerium-zirconium composite oxide coated with silica. The outer silica layer reduces direct contact and agglomeration between the cerium-zirconium composite oxides and provides condensable surface groups for subsequent silane modification. γ-ureidopropyltriethoxysilane and acryloyloxypropyltrimethoxysilane, after hydrolysis, condense with the silica coating layer, resulting in composite particles possessing both urea structures and polymerizable acryloyl groups on their surface. The urea structure enhances the interfacial compatibility between the composite particles and polyurethane acrylate, while the acryloyl groups participate in the free radical cross-linking and curing of the topcoat under the action of a photoinitiator. This fixes the inorganic composite particles within a UV-curable network, thereby reducing particle agglomeration and interfacial defects, and improving the transparency and abrasion resistance of the topcoat.

[0020] The modified cerium-zirconium composite particles in the topcoat can weaken the transmission of ultraviolet light into the coating interior and improve the coating's resistance to friction and wear through the inorganic reinforcement structure; UV-1164 further absorbs ultraviolet light that enters the topcoat interior, and the two work together to slow down the photoaging of polyurethane acrylate and the fading of the pigment layer. Therefore, this invention uses mechanical cutting and graded grinding to form rounded corners, and sequentially applies a base coating, a pigment layer, and a transparent wear-resistant topcoat coating to the rounded corners, so that the color and gloss of the rounded corner area are coordinated with the color of the slab body, while improving the wear resistance and weather resistance of the color-correcting layer and avoiding color changes caused by traditional hot bending processing.

[0021] Preferably, the method for preparing the modified composite particles includes the following steps:

[0022] S1. Cerium salt and zirconium salt are co-precipitated and calcined to obtain cerium-zirconium composite oxide;

[0023] S2. A silica coating layer is formed on the surface of the cerium-zirconium composite oxide to obtain a silica-coated cerium-zirconium composite oxide.

[0024] S3. The surface of the silica-coated cerium-zirconium composite oxide is modified using a silane coupling agent to obtain the modified composite particles.

[0025] Furthermore, the preparation method of the modified composite particles includes the following steps:

[0026] S1. Add 10-15 parts by weight of cerium nitrate hexahydrate and 2-5 parts by weight of zirconium oxychloride octahydrate to 80-120 parts by weight of water, and stir at 300-500 rpm at room temperature until completely dissolved to obtain a cerium-zirconium mixed salt solution; heat the cerium-zirconium mixed salt solution to 50-70℃, and add 8%-15% ammonia water by mass dropwise under stirring at 400-600 rpm to adjust the pH of the mixture to 9.0-10.0, and stir the reaction at 50-70℃ and 400-600 rpm for 1.5-3 hours, and then let it stand for 6-12 hours; filter and wash until neutral; dry the washed precipitate at 80-120℃ for 6-12 hours, and then heat it to 400-500℃ at a heating rate of 1-3℃ / min, keep it at the temperature for calcination for 1.5-3 hours, cool and grind to obtain cerium-zirconium composite oxide;

[0027] S2. Weigh 8-12 parts by weight of cerium-zirconium composite oxide and add it to a mixture of 140-180 parts by weight of anhydrous ethanol and 30-50 parts by weight of water. Disperse the mixture by ultrasonication for 20-40 minutes, and then add 3-5 parts by weight of ammonia water with a mass fraction of 20%-30%. Mix 2-5 parts by weight of tetraethyl orthosilicate with 15-25 parts by weight of anhydrous ethanol and add it dropwise to the above dispersion over 20-40 minutes. After the addition is complete, continue stirring the reaction at 30-40℃ and 400-600 rpm for 3-6 hours. Centrifuge, wash, and dry to obtain silica-coated cerium-zirconium composite oxide.

[0028] S3. Add 0.8-1.5 parts by weight of the modifier to a mixture of 15-25 parts by weight of anhydrous ethanol and 1-3 parts by weight of water. Adjust the pH of the mixture to 4.0-5.0 using glacial acetic acid. Stir and hydrolyze at 20-30℃ for 20-40 minutes to obtain a composite modified solution. Weigh 8-12 parts by weight of silica-coated cerium-zirconium composite oxide and add it to 80-120 parts by weight of anhydrous ethanol. Disperse ultrasonically for 15-30 minutes. Under stirring at 400-600 rpm, add the composite modified solution dropwise to the resulting dispersion over 15-30 minutes. Stir and react in the dark at 50-70℃ and 300-500 rpm for 3-6 hours. After the reaction is complete, cool to room temperature, centrifuge, wash, dry, pulverize, and pass through a 150-250 mesh sieve to obtain the composite modified silica-coated cerium-zirconium composite oxide.

[0029] The modifier consists of 0.4-0.8 parts by weight of γ-ureidopropyltriethoxysilane and 0.2-0.6 parts by weight of acryloyloxypropyltrimethoxysilane.

[0030] Preferably, the silane coupling agent comprises a mixture of γ-ureidopropyltriethoxysilane and acryloyloxypropyltrimethoxysilane.

[0031] Preferably, the UV-curable transparent wear-resistant topcoat coating comprises the following raw materials in parts by weight: 15-25 parts of isoborneol acrylate, 8-18 parts of 1,6-hexanediol diacrylate, 55-70 parts of aliphatic polyurethane acrylate, 2-8 parts of the modified composite particles, 0.5-1.5 parts of ultraviolet absorber, 0.3-1.0 parts of non-aqueous polymeric dispersant, 1-3 parts of photoinitiator, and 0.1-0.8 parts of leveling agent; wherein the non-aqueous polymeric dispersant is a polyester-modified polyamine polymeric dispersant.

[0032] Preferably, the non-aqueous polymeric dispersant is BASF 4310 dispersant, with an effective ingredient content of not less than 95% and a water content of not more than 0.5%.

[0033] The non-aqueous polymeric dispersant interacts with the surface of the modified composite particles through the adsorption groups in the polyamine structure, and improves the compatibility of the modified composite particles with acrylate monomers and aliphatic polyurethane acrylates through polyester segments, thereby reducing the aggregation of composite particles in the non-aqueous UV curing system.

[0034] Preferably, the color-correcting coating comprises the following raw materials in parts by weight: 20-30 parts of a mixed colorant composed of rutile titanium dioxide, calcium carbonate and iron oxide yellow, 65-80 parts of water-based acrylic resin, 1-2 parts of water-based polymeric dispersant and 0.2-1 parts of defoamer.

[0035] Preferably, the aqueous polymeric dispersant includes one or more of sodium polyacrylate, ammonium polyacrylate, styrene-maleic anhydride copolymer ammonium salt, polyvinylpyrrolidone, and polyether-modified polycarboxylate ammonium salt, with ammonium polyacrylate being preferred; the defoamer includes one or more of polydimethylsiloxane emulsion, polyether-modified polysiloxane, polypropylene glycol, 2,4,7,9-tetramethyl-5-decyn-4,7-diol, and mineral oil-based defoamers, with polyether-modified polysiloxane being preferred.

[0036] Preferably, the UV curing treatment is performed using ultraviolet light with a wavelength of 365nm, an irradiation energy of 1500-2500mJ / cm², a curing time of 30-60s, and a surface temperature of 65-75℃ for the rounded corners during the curing process.

[0037] Preferably, after the surface coating is UV cured, the slab body is cooled to room temperature, and then the surface coating is wet-polished using a 2000-5000 mesh water grinding pad. Subsequently, it is polished using a water-based diamond polishing slurry containing synthetic diamond microparticles with a particle size of 0.5-2μm, so that the 60° gloss difference between the color-corrected area and the adjacent slab body surface is no greater than 5GU.

[0038] Preferably, the aqueous diamond polishing slurry comprises the following raw materials in parts by weight: 1-5 parts synthetic diamond micropowder, 3-8 parts polyol, 0.1-0.5 parts aqueous dispersant, 0.1-0.5 parts nonionic surfactant, and 86-95 parts deionized water; the synthetic diamond micropowder has a particle size D50 of 0.5-2 μm, the polyol is one or more of glycerol, ethylene glycol, or propylene glycol, and the aqueous dispersant is sodium polyacrylate.

[0039] A rounded-corner rock slab with a color-correcting layer is prepared using the aforementioned processing method.

[0040] The beneficial effects of this invention are:

[0041] 1. This invention employs a cold-working method of mechanical cutting and graded grinding to form rounded corners on the edges of the slab. This eliminates the need to heat the slab to its softening temperature for hot bending, thus avoiding surface color changes, glaze defects, and thermal stress cracking caused by high-temperature processing. It also reduces reliance on high-temperature furnaces and specialized hot-bending molds. By controlling the cutting, grinding, and polishing parameters, a lower surface roughness can be achieved in the rounded corners, providing a stable surface foundation for the subsequent uniform application of the color-correcting layer.

[0042] 2. This invention sequentially applies a base coating, a colorant layer, and a transparent, wear-resistant topcoat coating to the rounded corners. The base coating covers and smooths the micropores formed after cutting; the colorant layer compensates for the color difference between the rounded corner cutting surface and the decorative surface of the slab; and the transparent topcoat protects the colorant layer without significantly affecting its color. After the topcoat has cured, wet grinding and polishing can adjust the surface gloss of the color-corrected area, creating a harmonious transition in color and gloss between the rounded corner area and the slab itself.

[0043] 3. This invention involves depositing a silica coating layer on the surface of a cerium-zirconium composite oxide and modifying the composite surface using γ-ureidopropyltriethoxysilane and acryloyloxypropyltrimethoxysilane. The silica coating layer improves the surface condition and dispersion uniformity of the cerium-zirconium composite oxide; ureidosilane enhances the interfacial compatibility between the modified composite particles and polyurethane acrylate; and acryloyloxysilane participates in crosslinking during UV curing, stabilizing the modified composite particles within the cured network, thereby reducing particle aggregation and shedding, and improving the transparency and abrasion resistance of the topcoat.

[0044] 4. This invention uses modified silica-coated cerium-zirconium composite oxide in combination with UV-1164, which can provide multiple protections against ultraviolet light, slow down the yellowing of the topcoat resin and the fading of the colorant layer, reduce the color difference and gloss change between the color-corrected area and the rock slab body after long-term light exposure, and make the resulting rounded corner rock slab have better weather resistance, wear resistance and long-term appearance stability. Detailed Implementation

[0045] 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.

[0046] The raw materials described in this application are partially described; all other raw materials not described are commercially available.

[0047] E-51 epoxy resin was purchased from Henan Hangcai Technology Co., Ltd., brand name: E-51.

[0048] The polyamide curing agent was purchased from Shandong Shenglilong Chemical Technology Co., Ltd., with an amine value of 80-220 mgKOH / g and a model number of 650.

[0049] The water-based acrylic resin was purchased from Jining Tangyi Chemical Co., Ltd., model number: J-676.

[0050] The water-based ammonium polyacrylate was purchased from Foshan Zhaojing Environmental Protection Technology Co., Ltd., model: Solewend AN33.

[0051] The polyether-modified polysiloxane was purchased from Jining Tangyi Chemical Co., Ltd., model number: JP-M031.

[0052] The aliphatic polyurethane acrylate was purchased from Shanghai Zhenlishi Network Technology Co., Ltd., item number: EBECRYL242.

[0053] The polyether-modified siloxane leveling agent was purchased from Guangdong San Ding Jia New Material Technology Co., Ltd., model number: 3007.

[0054] The diamond micron powder was purchased from Forsmann Technology (Beijing) Co., Ltd., item number: 0602110.

[0055] The fatty alcohol polyoxyethylene ether was purchased from Nantong Lianli New Materials Co., Ltd., model: MOA-3.

[0056] Sodium polyacrylate was purchased from Wuhan Jiyesheng Chemical Co., Ltd., code: JYS14715.

[0057] The UV absorber UV-1164 was purchased from Guangzhou Shanghe Chemical Technology Co., Ltd., model number: UV-1164.

[0058] The BASF 4310 dispersant was purchased from Shanghai Jingyan Chemical Co., Ltd., model: BASF EFKA PX4310.

[0059] Example 1

[0060] A method for processing rounded corner slabs with a color-correcting layer includes the following steps:

[0061] (1) Rounding: Select a beige quartz slab with dimensions of 1200mm×600mm×12mm as the slab body. The 60° gloss of the slab body surface is 60GU. Fix the slab body horizontally on a CNC slab grinding machine. Use a diamond grinding wheel with a diameter of 150mm and a grit of 80 mesh to cut the intersection area of ​​the adjacent two sides of the slab body to form a rounded corner with a radius of 2cm on the outer contour of the slab body. The rotation speed of the diamond grinding wheel is set to 4000rpm, the feed speed of the slab body is set to 10mm / s, and water cooling is used to cool the slab body during the cutting process. The cooling water flow rate is 2L / min.

[0062] (2) Grinding and polishing: In the first stage, use 800-grit silicon carbide sandpaper to dry grind the rounded corners for 3 minutes to remove obvious tool marks formed by cutting.

[0063] In the second stage, the rounded corners are wet-ground using 1200-grit alumina sandpaper. Water is used as a lubricant during the wet-ground process, and the grinding time is 5 minutes.

[0064] In the third stage, the rounded corners were wet-polished using 2000-grit zirconia sandpaper for 8 minutes. After polishing, the surface of the rounded corners was rinsed with clean water and then compressed air was used to blow away any remaining moisture and debris. After polishing, the surface roughness Ra of the arc-shaped cutting surface of the rounded corners was 0.6 ± 0.1 μm.

[0065] (3) Cleaning of rounded corner surfaces: Wipe the rounded corner surfaces with anhydrous ethanol, then dry the rock slab at 60°C for 10 minutes, and then cool it to room temperature.

[0066] (4) Preparation and application of the base coat: E-51 epoxy resin and polyamide curing agent are mixed at a mass ratio of 100:50 and stirred at 500 rpm for 5 min to obtain a transparent base coat; the transparent base coat is uniformly applied to the rounded corner surface by roller coating, and the thickness of the base coat after curing is controlled to be 8 μm; after coating, the rock slab is placed at 60℃ for 60 min to cure, and then cooled to room temperature;

[0067] (5) Preparation and coating of colorant layer: The colorant is evenly sprayed onto the surface of the base coating. The spraying pressure is 0.4MPa, the spraying distance is 20cm, and the dry film thickness is controlled to be 5μm. After spraying, it is allowed to stand and level for 2min, and then placed at 60℃ to dry for 15min.

[0068] (6) Coating of the topcoat: The UV-cured transparent wear-resistant topcoat is uniformly coated on the surface of the colorant layer by spraying, and the UV-cured transparent wear-resistant topcoat covers the junction of the rounded corner and the surface of the rock slab. The spraying pressure is 0.15MPa, the spraying distance is 15cm, and the dry film thickness of the topcoat after curing is controlled to be 15μm. After spraying, it is allowed to stand at room temperature for 3min to level.

[0069] (7) UV curing: The slab body coated with the topcoat is placed in a UV curing machine and irradiated with ultraviolet light with a wavelength of 365nm and an irradiation energy of 2000mJ / cm². The curing time is 45s. During the curing process, the surface temperature of the rounded corners is controlled at 70±5℃. After UV curing, the slab body is removed from the UV curing machine and allowed to cool naturally to room temperature. The topcoat is wet-polished for 60s using a 3000-mesh water grinding pad at a speed of 800rpm, a pressure of 10N, and a continuous water supply. Then, the topcoat is polished for 90s using a soft wool polishing pad and the water-based diamond polishing liquid at a speed of 1000rpm and a pressure of 8N until the 60° gloss of the color-corrected area is 60±2GU, and the difference in 60° gloss between the color-corrected area and the surface of the adjacent slab body is no more than 5GU. After polishing, the slab body is cleaned with deionized water and then dried with compressed air to obtain a rounded corner slab with a color-corrected layer.

[0070] The color-correcting coating in step (5) is prepared as follows: rutile titanium dioxide, calcium carbonate and iron oxide yellow are weighed according to a mass ratio of 85:12:3, and the three are mixed evenly to obtain a beige pigment; 25 parts by weight of the beige pigment, 73 parts by weight of waterborne acrylic resin with a solid content of 45%, 1.5 parts by weight of waterborne ammonium polyacrylate and 0.5 parts by weight of polyether-modified polysiloxane are mixed and dispersed at 1000 rpm for 15 min to obtain the color-correcting coating.

[0071] The preparation method of the UV-cured transparent wear-resistant topcoat coating in step (6) is as follows: 18 parts by weight of isoborneol acrylate, 12 parts by weight of 1,6-hexanediol diacrylate, and 0.7 parts by weight of BASF 4310 dispersant are mixed and stirred at 500 rpm for 5 min. Under stirring conditions, 4 parts by weight of modified silica-coated cerium-zirconium composite oxide are added and dispersed at 1500 rpm for 20 min. Then, the mixture is ground with zirconia beads to ensure that the dispersed particle size D90 of the composite particles is not greater than 120 nm, thus obtaining the composite particles. The pre-dispersion solution was prepared by adding 62 parts by weight of aliphatic polyurethane acrylate and 1 part by weight of UV absorber UV-1164. The mixture was stirred at 800 rpm for 15 min, and then 2 parts by weight of ethyl 2,4,6-trimethylbenzoylphenylphosphonate and 0.3 parts by weight of polyether-modified siloxane leveling agent were added in the dark. The mixture was stirred at 500 rpm for 10 min. The resulting mixture was then degassed under vacuum at -0.08 MPa for 5 min and filtered through a 200-mesh filter to obtain a UV-curable transparent wear-resistant topcoat.

[0072] The preparation method of the modified silica-coated cerium-zirconium composite oxide is as follows:

[0073] S1. Add 12 parts by weight of cerium nitrate hexahydrate and 3 parts by weight of zirconium oxychloride octahydrate to 100 parts by weight of water, and stir at 400 rpm at room temperature until completely dissolved to obtain a cerium-zirconium mixed salt solution; heat the cerium-zirconium mixed salt solution to 60°C, and add 10% ammonia water dropwise under stirring at 500 rpm to adjust the pH of the mixture to 9.5, stir at 60°C and 500 rpm for 2 hours, and then let it stand for aging for 8 hours; filter and wash until neutral; dry the washed precipitate at 100°C for 8 hours, and then heat it to 450°C at a heating rate of 2°C / min, keep it at the temperature for 2 hours, cool it and grind it to obtain cerium-zirconium composite oxide;

[0074] S2. Weigh 10 parts by weight of cerium-zirconium composite oxide and add it to a mixture of 160 parts by weight of anhydrous ethanol and 40 parts by weight of water. Disperse the mixture by ultrasonication for 30 min, and then add 4 parts by weight of ammonia water with a mass fraction of 25%. Mix 3 parts by weight of tetraethyl orthosilicate with 20 parts by weight of anhydrous ethanol and add it dropwise to the above dispersion over 30 min. After the addition is complete, continue stirring the reaction at 35°C and 500 rpm for 4 h. Centrifuge, wash, and dry to obtain silica-coated cerium-zirconium composite oxide.

[0075] S3. Add 1 part by weight of the modifier to a mixture of 20 parts by weight of anhydrous ethanol and 2 parts by weight of water. Adjust the pH of the mixture to 4.5 using glacial acetic acid. Stir and hydrolyze at 25°C for 30 min to obtain a composite modified solution. Weigh 10 parts by weight of silica-coated cerium-zirconium composite oxide and add it to 100 parts by weight of anhydrous ethanol. Disperse ultrasonically for 20 min. Under stirring at 500 rpm, add the composite modified solution dropwise to the resulting dispersion over 20 min. Stir and react in the dark at 60°C and 400 rpm for 4 h. After the reaction is complete, cool to room temperature, centrifuge, wash, dry, pulverize and pass through a 200-mesh sieve to obtain the composite modified silica-coated cerium-zirconium composite oxide.

[0076] The modifier consists of 0.6 parts by weight of γ-ureidopropyltriethoxysilane and 0.4 parts by weight of acryloyloxypropyltrimethoxysilane.

[0077] The diamond polishing solution in step (7) UV curing consists of 3 parts by weight of diamond micro powder, 5 parts by weight of glycerol, 0.2 parts by weight of sodium polyacrylate, 0.2 parts by weight of fatty alcohol polyoxyethylene ether, and 91.6 parts by weight of deionized water. During preparation, sodium polyacrylate and fatty alcohol polyoxyethylene ether are first added to deionized water and stirred at 500 rpm for 5 min. Then, glycerol and artificial diamond micro powder are added and dispersed at 1000 rpm for 15 min to obtain the aqueous diamond polishing solution.

[0078] Example 2

[0079] The method is basically the same as in Example 1, except that the amount of modified silica-coated cerium-zirconium composite oxide in the UV-cured transparent wear-resistant coating is adjusted from 4 parts by weight to 2 parts by weight, and the amount of aliphatic polyurethane acrylate is adjusted from 62 parts by weight to 64 parts by weight. The other raw materials and preparation methods are the same as in Example 1.

[0080] Example 3

[0081] The method is basically the same as in Example 1, except that the amount of modified silica-coated cerium-zirconium composite oxide in the UV-cured transparent wear-resistant coating is adjusted from 4 parts by weight to 6 parts by weight, and the amount of aliphatic polyurethane acrylate is adjusted from 62 parts by weight to 60 parts by weight. The other raw materials and preparation methods are the same as in Example 1.

[0082] Example 4

[0083] The preparation method is basically the same as that in Example 1, except that the modifier in the preparation method of the modified silica-coated cerium-zirconium composite oxide is 1 part by weight of γ-ureidopropyltriethoxysilane, and the other raw materials and preparation methods are the same as those in Example 1.

[0084] Example 5

[0085] The preparation method is basically the same as that in Example 1, except that the modifier in the preparation method of the modified silica-coated cerium-zirconium composite oxide is 1 part by weight of acryloyloxypropyltrimethoxysilane, and the other raw materials and preparation methods are the same as those in Example 1.

[0086] Comparative Example 1

[0087] The method is basically the same as in Example 1, except that: no modified silica-coated cerium-zirconium composite oxide is added to the UV-cured transparent wear-resistant topcoat, and the amount of aliphatic polyurethane acrylate is adjusted from 62 parts by weight to 66 parts by weight. The other raw materials and preparation methods are the same as in Example 1.

[0088] Comparative Example 2

[0089] The process is basically the same as in Example 1, except that the S2 silica coating step is omitted in the preparation of the modified composite particles. Instead, the cerium-zirconium composite oxide obtained in S1 is directly modified on the surface using the method described in S3, with 0.6 parts by weight of γ-ureidopropyltriethoxysilane and 0.4 parts by weight of acryloyloxypropyltrimethoxysilane to obtain the modified cerium-zirconium composite oxide. In the topcoat, 4 parts by weight of the modified cerium-zirconium composite oxide are used to replace the modified silica coating of the cerium-zirconium composite oxide in Example 1. The remaining raw materials and preparation methods are the same as in Example 1.

[0090] Comparative Example 3

[0091] The process is basically the same as in Example 1, except that in the preparation of the modified composite particles, in S3, 0.6 parts by weight of γ-ureidopropyltriethoxysilane and 0.4 parts by weight of acryloyloxypropyltrimethoxysilane are not used. Instead, 1 part by weight of KH-570 is used to modify the surface of the silica-coated cerium-zirconium composite oxide. The remaining raw materials and preparation methods are the same as in Example 1.

[0092] Comparative Example 4

[0093] The method is basically the same as that in Example 1, except that the UV-cured transparent wear-resistant topcoat does not contain UV absorber UV-1164, the amount of aliphatic polyurethane acrylate is adjusted from 62 parts by weight to 63 parts by weight, and the other raw materials and preparation methods are the same as those in Example 1.

[0094] Test Example 1

[0095] Initial color consistency test of the color-corrected area: Five rounded corner rock slabs with color-corrected layers prepared in Examples 1-5 and Comparative Examples 1-4 were taken respectively and placed in an environment with a temperature of 23±2℃ and a relative humidity of 50±5% for 7 days before testing.

[0096] According to GB / T 3978-2008 "Standard Illuminating Bodies and Geometric Conditions" and GB / T 3979-2008 "Methods for Measuring the Color of Objects", an integrating sphere spectrophotometer was used for testing; d / 8 measurement geometry, specular reflection light exclusion mode, 10° standard observer, and a small aperture spectrophotometer with a measurement aperture of no more than 4 mm were used, and a curved surface positioning fixture was set to make the instrument's measurement axis coincide with the normal of the curved surface at the measurement point.

[0097] Under D65 and F11 standard illuminators, measurements were taken of the color-corrected area at the rounded corners and the adjacent uncorrected surface of the rock slab. Value. Five measurement points were evenly selected on the color-corrected area and the adjacent rock slab surface of each sample, the average value was taken, and the color difference ΔE00 between the two areas was calculated according to the CIEDE2000 color difference formula in GB / T 7921-2008 "Uniform Color Space and Color Difference Formula".

[0098] Table 1 Initial Color Consistency Test Results

[0099] Test Example 2

[0100] Color and gloss stability test after artificial climate aging: Take 5 samples each from Examples 1-5 and Comparative Examples 1-4 and conduct xenon arc lamp artificial climate aging test according to GB / T 1865-2009 "Artificial climate aging and artificial radiation exposure of paints and varnishes with filtered xenon arc radiation".

[0101] A xenon arc aging test chamber with a sunlight filter was used, and the test conditions were as follows: irradiance at 340 nm was 0.51 W / (m²·nm), black panel temperature was 63±3℃, and relative humidity was 50±5%; a cycle consisted of continuous light irradiation for 102 min followed by light irradiation and water spraying for 18 min, with a cumulative aging time of 500 h. The rounded corner color-corrected area and the adjacent surface of the rock slab were all placed within the effective irradiation area.

[0102] After aging, the samples were placed in an environment with a temperature of 23±2℃ and a relative humidity of 50±5% for 24 hours. Following the method in Test Example 1, the color difference ΔE00 between the rounded corner color-corrected area and the surface of the adjacent rock slab was measured under D65 and F11 illuminators, respectively.

[0103] According to GB / T 9754-2025 "Determination of 20°, 60° and 85° gloss of paints and varnishes", the 60° gloss of the color-corrected area was measured before and after aging.

[0104] Gloss retention rate is calculated according to the following formula: R G =G1 / G0×100%

[0105] In the formula, R G Gloss retention rate, %

[0106] G0 represents the 60° gloss level of the sample before aging, GU; G1

[0107] The gloss level (GU) at 60° after aging is given. The test results are shown in Table 2.

[0108] Table 2. Color difference ΔE00 between the aging-repaired area and the main body of the slab under D65 illumination.

[0109] Test Example 3

[0110] Abrasion resistance test of the topcoat: Due to the arc-shaped structure of the rounded corners, it is inconvenient to directly install them on the abrasion tester. Flat accompanying test panels were prepared using the same batch of sintered stone as in each embodiment and comparative example. The decorative layer on the surface of the accompanying test panels was removed to expose the sintered stone substrate, and then the exposed substrate surface was polished to Ra 0.6±0.1μm. Subsequently, the corresponding formulations, thicknesses, and curing conditions of the primer coating, pigment layer, and topcoat coating for each group were followed, and 5 accompanying test panels were prepared for each group.

[0111] 1. Abrasion resistance

[0112] The test was conducted according to GB / T 1768-2006, "Determination of Abrasion Resistance of Paints and Varnishes - Rotary Rubber Grinding Wheel Method". The test panels were placed at 23±2℃ and 50±5% relative humidity for 7 days, cleaned, and their initial mass was measured. CS-10 rubber grinding wheels were used, with a load of 500g applied to each wheel. The turntable speed was 60±2 rpm, and the abrasion was measured over 1000 revolutions. After the test, abrasion debris was removed from the surface of the test panels using a soft brush and compressed air. The panels were then placed in the same environment for 2 hours and weighed again.

[0113] The wear resistance mass loss is calculated according to the following formula: W=m0-m1

[0114] In the formula, W represents the mass loss after 1000 revolutions of wear, in mg; m0 represents the mass of the test plate before the test, in mg; and m1 represents the mass of the test plate after the test, in mg. The smaller the mass loss, the better the wear resistance of the topcoat.

[0115] Table 3. Test results of abrasion resistance of the topcoat

[0116] As shown in the table above, the amount of modified silica-coated cerium-zirconium composite oxide added simultaneously affects the transparency, weather resistance, and abrasion resistance of the topcoat. In Example 2, reducing the amount of modified composite particles resulted in weaker opacity and light scattering of the colorant layer in the topcoat, leading to better initial color consistency. However, its shielding effect against ultraviolet light and its inorganic reinforcing effect on the topcoat were correspondingly weakened, resulting in decreased color stability, gloss retention, and abrasion resistance after artificial weathering. In Example 3, increasing the amount of modified composite particles further improved the abrasion resistance of the topcoat, but the increased inorganic particle content increased light scattering and the possibility of particle agglomeration, leading to a slight increase in initial color difference. Example 1, using a moderate amount of modified composite particles, effectively balanced color consistency, weather resistance, and abrasion resistance. Example 4 used only γ-ureidopropyltriethoxysilane for surface modification. This modifier can improve the polar compatibility and interfacial bonding between inorganic composite particles and organic resins, but it cannot directly participate in the UV crosslinking of the acrylate system. Therefore, the resulting topcoat coating has lower abrasion resistance and long-term weathering stability than Example 1. Example 5 uses only acryloyloxypropyltrimethoxysilane for surface modification. Its acryloyl group can participate in the UV curing reaction, which is beneficial to improving the fixation degree of inorganic particles in the cured network and the abrasion resistance of the topcoat coating. However, it lacks the urea group structure to improve the interfacial compatibility between inorganic particles and polyurethane acrylate. Therefore, the particle dispersion stability and the overall color difference stability after aging are still lower than those of Example 1.

[0117] Compared to Example 1, Comparative Example 1 did not include modified silica-coated cerium-zirconium composite oxide. Due to the reduced inorganic particle content in the topcoat, its initial transparency was better, and its impact on the color of the pigment layer was smaller; however, lacking the UV shielding and abrasion resistance enhancement provided by the inorganic composite particles, it was more prone to resin yellowing, gloss reduction, and pigment layer color drift after artificial weathering. Simultaneously, the abrasion resistance of the topcoat was significantly reduced. Comparative Example 2 omitted the silica coating step, and the cerium-zirconium composite oxide was directly modified with silane. Because the surface of the cerium-zirconium composite oxide lacked a continuous silica coating layer, the active sites available for silane hydrolysis and condensation on the surface were insufficient and their distribution uniformity was inadequate. This reduced the dispersion stability of particles in the organic topcoat, making it easy to form secondary agglomerates and generate strong light scattering, leading to increased initial color difference. At the same time, the lack of a silica coating layer made it difficult for the cerium-zirconium composite oxide to form a stable and uniform inorganic reinforcing structure in the topcoat layer, thus reducing abrasion resistance, color stability after aging, and gloss retention. Comparative Example 3 used conventional KH-570 to modify silica-coated cerium-zirconium composite oxide. While the unsaturated groups in KH-570 can participate in UV curing, it lacks the urea-based interface structure provided by γ-ureidopropyltriethoxysilane, limiting its improvement on the compatibility and interfacial bonding between inorganic particles and polyurethane acrylate. Comparative Example 4, without UV-1164, exhibited wear resistance similar to Example 1, indicating that UV-1164 is not the primary source of wear resistance. However, its color difference and gloss loss after artificial weathering significantly increased, suggesting that modified cerium-zirconium composite particles alone are insufficient to adequately suppress the long-term photoaging of the topcoat resin and colorant layer. The modified composite particles can shield ultraviolet light, while UV-1164 can absorb ultraviolet light penetrating the topcoat coating. The combined effect of these two components further reduces yellowing of the topcoat layer, fading of the colorant layer, and gloss degradation.

Claims

1. A method for processing rounded corner slabs with a color-correcting layer, characterized in that, Includes the following steps: (1) The intersection area of ​​the adjacent two sides of the rock slab body is cut and processed to form a rounded corner on the outer contour of the rock slab body. The rounded corner has an arc-shaped cutting surface extending along the thickness direction of the rock slab. (2) Grind and polish the rounded corner to make the surface roughness Ra of the rounded corner 0.5-0.7μm; (3) Clean the surface of the rounded corners; (4) Apply a base coat and a colorant layer sequentially to the rounded corner surface; A UV-curable transparent abrasion-resistant topcoat is coated on the surface of the pigment layer. The UV-curable transparent abrasion-resistant topcoat contains modified composite particles, which are cerium-zirconium composite oxides with silica surface modified by a silane coupling agent. The silane coupling agent is γ-ureopropyltriethoxysilane and / or acryloyloxypropyltrimethoxysilane. The UV-curable transparent abrasion-resistant topcoat also contains a UV absorber. (5) The UV-curable transparent wear-resistant topcoat is subjected to UV curing treatment to cure the UV-curable transparent wear-resistant topcoat to form a topcoat coating.

2. The processing method according to claim 1, characterized in that, The cutting process is performed using a diamond grinding wheel with a rotation speed of 3000-5000 rpm, and the feed speed of the rock slab body is 8-15 mm / s; the grinding and polishing process includes coarse grinding with 600-1000 grit sandpaper, fine grinding with 1000-1500 grit sandpaper, and polishing with 1800-2400 grit sandpaper in sequence.

3. The processing method according to claim 1, characterized in that, The base coating is formed by curing an epoxy resin system, and its dry film thickness is 5-15 μm; the colorant layer is formed by color-correcting paint, and its dry film thickness is 3-10 μm; the topcoat coating has a dry film thickness of 10-25 μm.

4. The processing method according to claim 1, characterized in that, The method for preparing the modified composite particles includes the following steps: S1. Cerium salt and zirconium salt are co-precipitated and calcined to obtain cerium-zirconium composite oxide; S2. A silica coating layer is formed on the surface of the cerium-zirconium composite oxide to obtain a silica-coated cerium-zirconium composite oxide. S3. The surface of the silica-coated cerium-zirconium composite oxide is modified using a silane coupling agent to obtain the modified composite particles.

5. The processing method according to claim 4, characterized in that, The silane coupling agent comprises a mixture of γ-ureidopropyltriethoxysilane and acryloyloxypropyltrimethoxysilane.

6. The processing method according to claim 1, characterized in that, The UV-curable transparent wear-resistant topcoat coating comprises the following raw materials in parts by weight: 15-25 parts of isoborneol acrylate, 8-18 parts of 1,6-hexanediol diacrylate, 55-70 parts of aliphatic polyurethane acrylate, 0.5-1.5 parts of UV absorber, 0.3-1.0 parts of non-aqueous polymeric dispersant, 2-8 parts of the modified composite particles, 1-3 parts of photoinitiator, and 0.1-0.8 parts of leveling agent; the non-aqueous polymeric dispersant is a polyester-modified polyamine polymeric dispersant.

7. The processing method according to claim 3, characterized in that, The color-correcting coating comprises the following raw materials in parts by weight: 20-30 parts of a mixed colorant composed of rutile titanium dioxide, calcium carbonate and iron oxide yellow, 65-80 parts of water-based acrylic resin, 1-2 parts of water-based polymeric dispersant and 0.2-1 parts of defoamer.

8. The processing method according to claim 1, characterized in that, The UV curing treatment is performed using ultraviolet light with a wavelength of 365nm, an irradiation energy of 1500-2500mJ / cm², a curing time of 30-60s, and a surface temperature of 65-75℃ for the rounded corners during the curing process.

9. The processing method according to claim 1, characterized in that, After the surface coating is UV cured, the slab body is cooled to room temperature, and then wet-polished with a 2000-5000 mesh water grinding pad. Subsequently, it is polished with a water-based diamond polishing slurry containing artificial diamond microparticles with a particle size of 0.5-2μm, so that the gloss difference between the color-corrected area and the surface of the adjacent slab body at 60° is no greater than 5GU.

10. A rounded-corner slab with a color-correcting layer, characterized in that, It is prepared by the processing method according to any one of claims 1-9.

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