A spraying method for assembling a scratch-resistant and moisture-resistant coating for kitchen and bathroom

Abstract

The application discloses a spraying method of an assembled kitchen and bathroom scratch-resistant and moisture-resistant coating, and relates to the technical field of surface protective coating of assembled buildings. The application comprises the following steps: step S1, performing pretreatment on the surface of an assembled kitchen and bathroom substrate to be sprayed, wherein the pretreatment at least comprises polishing treatment to roughen the surface of the substrate; and step S2, applying a primer on the pretreated substrate surface, wherein the primer is an adhesion-promoting primer. According to the application, the polishing roughening treatment and the adhesion-promoting primer containing a silane coupling agent are synergistically used, so that micro mechanical locking and chemical bonding are simultaneously formed between a polyurea coating and an organic polymer substrate, the interfacial bonding strength can reach more than 60 MPa, the application is superior to a traditional spraying process, and the problems of coating blistering, cracking and peeling are solved; the polyurea coating has comprehensive properties of high strength, high elasticity, wear resistance, chemical medium resistance, impact resistance and water and moisture resistance, and the surface is dense after solidification, and the pencil hardness can reach more than 4H.

Description

Technical Field

[0001] This invention relates to the field of surface protective coating technology for prefabricated buildings, and specifically to a spraying method for a scratch-resistant and moisture-proof coating for prefabricated kitchens and bathrooms. Background Technology

[0002] Prefabricated kitchens and bathrooms refer to kitchen and bathroom spaces where various functional modules (such as wall panels, floor panels, and connectors) are prefabricated in a factory and then transported to the construction site for rapid assembly. Compared with traditional on-site wet construction, prefabricated kitchens and bathrooms have significant advantages such as faster construction speed, controllable quality, and environmental protection and energy saving, and have been widely used in the fields of residential industrialization and prefabricated buildings in recent years.

[0003] Currently, the wall panels and base panels of prefabricated kitchens and bathrooms mostly use organic polymer substrates (such as PVC, PE, PP and other plastics or composite materials). Their surfaces need to have excellent scratch resistance, moisture and water resistance, and corrosion resistance to cope with the high humidity, frequent cleaning, and potential chemical detergent corrosion that occur in kitchens and bathrooms over a long period of time. Therefore, a protective coating is usually sprayed onto the substrate surface.

[0004] However, existing spraying methods for prefabricated kitchen and bathroom surface coatings have the following main shortcomings: Organic polymer substrates are low surface energy materials, resulting in poor adhesion to conventional coatings. Current spraying processes often involve simple cleaning followed by direct spraying without effective roughening or chemical coupling treatment of the substrate surface. This leads to insufficient bonding strength between the coating and the substrate, making the coating prone to blistering, cracking, and even large-area peeling during use. Some technologies focus solely on waterproofing, neglecting scratch and impact resistance; others, while using abrasion-resistant coatings, struggle to address moisture and chemical corrosion resistance. A single coating cannot simultaneously meet the diverse performance requirements of kitchens and bathrooms, while multi-layer composite coatings suffer from poor interlayer compatibility and complex application. Furthermore, traditional spraying processes involve slow curing, consuming significant production space and time, impacting factory efficiency. The curing process is also sensitive to environmental temperature and humidity; in humid environments, the coating is prone to pinholes and whitening defects, leading to unstable coating quality and a high scrap rate.

[0005] Therefore, a spraying method for prefabricated kitchen and bathroom scratch-resistant and moisture-proof coatings is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a method for spraying a prefabricated kitchen and bathroom scratch-resistant and moisture-proof coating in order to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention specifically adopts the following technical solution: A method for spraying a scratch-resistant and moisture-proof coating for prefabricated kitchens and bathrooms includes the following steps: Step S1: Perform pretreatment on the surface of the prefabricated kitchen and bathroom substrate to be sprayed. The pretreatment includes at least sanding to roughen the surface of the substrate. Step S2: Apply a primer to the pretreated substrate surface, wherein the primer is an adhesion-promoting primer; Step S3: Apply a two-component spray polyurea coating to the substrate surface with a primer. The A and B components of the two-component polyurea coating are preheated and then mixed and atomized for spraying to form a polyurea coating. The spraying is done in a multi-layer spraying method. Step S4: Curing the polyurea coating.

[0008] Furthermore, the pretreatment also includes cleaning and drying. The cleaning uses organic solvents to remove oil and impurities from the substrate surface, and the drying reduces the moisture content of the substrate surface to less than 5%.

[0009] Furthermore, the polishing process reduces the surface roughness Ra of the substrate to 3.2 μm to 6.3 μm, and after polishing, high-pressure air is used to blow away surface dust.

[0010] Furthermore, the primer is an epoxy primer or a polyurethane primer, and the primer contains 1% to 5% silane coupling agent by weight of the total primer.

[0011] Furthermore, the primer is sprayed to a thickness of 20μm to 50μm. After the primer is applied, it is left to dry at room temperature for 30min to 120min, or baked at 40℃ to 60℃ for 10min to 30min, so that the primer reaches a surface dry state.

[0012] Furthermore, in step S3, component A is preheated to 65°C to 75°C, component B is preheated to 70°C to 80°C, and the spraying pressure is 2000 psi to 3500 psi.

[0013] Furthermore, the multi-layer spraying is carried out in 2 to 3 coats, with each coat having a thickness of 0.5 mm to 1.5 mm and a total design thickness of 1.5 mm to 4.0 mm.

[0014] Furthermore, in step S3, the spraying environment temperature is 10℃~35℃ and the relative humidity is less than 85%; in step S4, the curing method is to cure at room temperature for more than 24 hours.

[0015] Furthermore, the substrate is an organic polymer substrate wall panel and / or base plate of a prefabricated kitchen and bathroom; the prefabricated kitchen and bathroom includes multiple vertically arranged wall panels, base plates and pins, with matching mounting grooves and fixing holes for mounting pins on the side walls of adjacent wall panels, and grooves for mounting wall panels provided around the base plate.

[0016] Furthermore, in step S3, for the inner surface of the wall panel, the total thickness of the polyurea coating is 2.0mm to 4.0mm; for the outer back surface of the wall panel, the total thickness of the polyurea coating is 0.5mm to 1.5mm; or for the grooved part of the base plate and the pin fixing hole part of the wall panel, before spraying the polyurea coating, a layer of polyurea coating is first applied to the groove surface and the inner wall of the hole as a base layer, and then the whole coating is sprayed.

[0017] The beneficial effects of this invention are as follows: By using a roughening process and enhancing adhesion with a silane coupling agent, the primer is enhanced, enabling the polyurea coating to simultaneously form microscopic mechanical interlocking and chemical bonding with the organic polymer substrate. The interfacial bonding strength reaches over 60 MPa, superior to traditional spraying processes, thus solving problems such as blistering, cracking, and peeling. The polyurea coating possesses comprehensive properties including high strength, high elasticity, wear resistance, chemical resistance, impact resistance, and waterproofing. After curing, the surface is dense, with a pencil hardness exceeding 4H, simultaneously meeting the multiple performance requirements of protective layers in kitchen and bathroom spaces. The coating is 100% solid. With low content and no solvent evaporation, it can be fully cured in 24 hours at room temperature and is not sensitive to humidity, curing normally even in humid environments. This avoids coating whitening and pinhole defects, shortens the production cycle, and improves quality stability. Different coating thicknesses and base coat sealing processes are set according to the differentiated protection requirements of the inner side of the wall panel, the outer back side, and the grooved and pin fixing holes of the base plate. This optimizes material usage and reduces costs while ensuring overall protection. Polyurea coatings do not contain organic solvents and have no VOC emissions during construction, meeting green environmental protection requirements. Attached Figure Description

[0018] Figure 1 This is a flowchart of the overall process of the present invention; Figure 2 This is a detailed flowchart of the substrate pretreatment process of the present invention; Figure 3 This is a schematic diagram illustrating the spraying principle of the polyurea scratch-resistant and moisture-proof coating of the present invention; Figure 4 This is a schematic cross-sectional view of the layered structure after the coating of the present invention is sprayed. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0022] In the description of the embodiments of the present invention, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0023] like Figures 1 to 4 As shown, a method for spraying a prefabricated kitchen and bathroom scratch-resistant and moisture-proof coating includes the following steps: Step S1: Perform pretreatment on the surface of the prefabricated kitchen and bathroom substrate to be sprayed. The pretreatment includes at least sanding to roughen the surface of the substrate. Step S2: Apply a primer to the pretreated substrate surface. The primer is an adhesion-promoting primer. Step S3: Apply a two-component spray polyurea coating to the substrate surface with a primer. The A and B components of the two-component polyurea coating are preheated separately, mixed, and atomized before being sprayed to form a polyurea coating. The spraying is done in multiple layers. Step S4: Curing the polyurea coating.

[0024] Pretreatment also includes cleaning and drying. Cleaning uses organic solvents to remove oil and impurities from the substrate surface, and drying makes the moisture content of the substrate surface less than 5%.

[0025] More specifically, organic solvent cleaning can effectively remove weak boundary layers such as mold release agents, oil stains, and dust from the surface of plastic substrates. Drying controls the moisture content to below 5%, preventing water vapor from escaping and forming bubbles during the subsequent curing process of the primer and polyurea coating 107. At the same time, the synergy between cleaning and drying increases the surface tension of the substrate, which is conducive to the primer fully wetting and penetrating the microstructure after sanding. This significantly improves the adhesion between the primer and the substrate, and avoids blistering of the coating due to the accumulation of interface moisture in a humid environment.

[0026] In some embodiments, the organic solvent may be any one or a combination of acetone, ethanol, and ethyl acetate.

[0027] The grinding process brings the surface roughness Ra of the substrate to 3.2μm to 6.3μm. After grinding, high-pressure air is used to blow away the surface dust, forming a roughened surface 110.

[0028] More specifically, the grinding process creates an anchoring structure of microscopic pits and protrusions on the substrate surface, with the roughness controlled within the range of 3.2μm to 6.3μm. This provides sufficient specific surface area for the primer to penetrate and form a mechanical interlock, while avoiding excessive roughness that could prevent the primer from fully wetting and creating interfacial porosity. High-pressure air purging removes the dust generated during grinding, preventing dust from forming a weak interfacial layer between the substrate and the primer, thus ensuring a continuous and dense adhesion interface between the primer layer and the substrate. This roughness range, combined with the high-pressure purging process, significantly improves the wettability and spreadability of the primer, laying the foundation for high-strength adhesion of the subsequent polyurea coating.

[0029] In some embodiments, the polishing process can be carried out by any of the following methods: sandpaper polishing, belt polishing, or sandblasting, such as mechanical polishing with 360-600 grit sandpaper.

[0030] The primer is an epoxy primer or a polyurethane primer, and the primer contains 1% to 5% silane coupling agent by weight of the total primer.

[0031] More specifically, epoxy or polyurethane primers possess excellent film-forming properties, mechanical properties, and resistance to chemical media, enabling the formation of a continuous primer layer. One end of the silane coupling agent can undergo a hydrolytic condensation reaction with the active groups on the substrate surface to form covalent bonds, while the other end can undergo a crosslinking reaction with the primer and polyurea coating, thereby forming a chemical bridge between the substrate and the polyurea coating. The synergistic effect of mechanical locking and chemical bonding significantly enhances the interfacial bonding strength between the polyurea coating and the organic polymer substrate, completely solving the industry problem of easy peeling of coatings on low surface energy substrates.

[0032] In some embodiments, the silane coupling agent may be any one or a combination of KH-550, KH-560, and KH-570, and its mass percentage may be configured to be 2% or 3%.

[0033] The primer should be sprayed to a thickness of 20μm to 50μm. After application, allow it to dry at room temperature for 30 to 120 minutes, or bake it at 40℃ to 60℃ for 10 to 30 minutes until it is surface dry.

[0034] More specifically, a thickness of 20μm to 50μm ensures that the primer layer uniformly covers the substrate surface and forms a continuous and complete transition layer. If the thickness is too thin, it will be difficult to completely cover the microscopic peaks and valleys of the roughened surface; if the thickness is too thick, internal stress will easily be generated and drying will be incomplete. By controlling the surface drying state, the silane coupling agent can be fully hydrolyzed and condensed to form a Si-O-Si cross-linked network, while avoiding solvent residue and over-curing. This maintains appropriate reactivity on the primer layer surface, thereby forming a strong chemical bond with the subsequent polyurea coating. This synergistic control of primer thickness and drying conditions provides a stable and highly active adhesion base for the polyurea coating, which is a key step in achieving high interfacial bonding strength. More specifically, the primer spraying thickness can be configured as 35μm, with static drying at room temperature for 60 minutes, or baking and drying at 50℃ for 20 minutes.

[0035] In step S3, component A is preheated to 65°C to 75°C, component B is preheated to 70°C to 80°C, and the spraying pressure is 2000 psi to 3500 psi.

[0036] More specifically, after preheating, component A in component A storage tank 201 and component B in component B storage tank are mixed and atomized by a mixing spray gun and sprayed onto the substrate surface to form a polyurea coating. Preheating reduces the viscosity of the two-component materials, allowing component A and component B to mix more evenly in the mixing spray gun, resulting in a more complete reaction and avoiding incomplete curing in some areas due to uneven mixing. The spraying pressure is controlled between 2000 psi and 3500 psi, ensuring that the coating droplets are fine and uniform in size and flow fully on the substrate surface with sufficient impact velocity, expelling interfacial gases and forming a dense coating free of pinholes and bubbles. Furthermore, since the polyurea reaction is insensitive to humidity, it can cure normally even in humid environments, overcoming the problems of whitening and pinhole defects that traditional coatings produce in humid environments. In some embodiments, the preheating temperature of component A can be configured to 70°C, the preheating temperature of component B can be configured to 75°C, and the spraying pressure can be configured to 2800 psi.

[0037] Multi-layer spraying involves 2 to 3 coats, with each coat having a thickness of 0.5 mm to 1.5 mm and a total design thickness of 1.5 mm to 4.0 mm.

[0038] More specifically, multi-coating ensures that each layer of polyurea coating has a moderate thickness, avoiding sagging, pinholes, and stress cracking that can occur with a single thick coat. Adjacent layers of the polyurea coating undergo a self-adhesive reaction to form chemical bonds, resulting in tight interlayer bonding. Simultaneously, interlayer gases can be fully expelled, ultimately forming a uniform, defect-free thick protective film. A total thickness of 1.5mm to 4.0mm meets the stringent requirements of kitchens and bathrooms for scratch resistance, impact resistance, and moisture resistance, while avoiding excessive increases in material costs and component weight. This multi-layer spraying method, combined with the range of thicknesses in a single coat, ensures rapid application while achieving excellent overall coating performance.

[0039] In some embodiments, multi-layer spraying can be configured to be sprayed in two coats, with a single coat thickness of 1.0 mm and a total thickness of 2.0 mm; or sprayed in three coats, with a single coat thickness of 0.8 mm and a total thickness of 2.4 mm.

[0040] The ambient temperature for spraying in step S3 is 10℃~35℃, and the relative humidity is below 85%; in step S4, the curing method is to let it stand at room temperature for more than 24 hours.

[0041] More specifically, the wide range of temperature and relative humidity control in the spraying application environment fully utilizes the humidity-insensitive nature of polyurea coatings, allowing the coating to cure normally even in humid environments. This avoids defects such as whitening and pinholes that occur with traditional coatings in high humidity. The polyurea coating can be fully cured by standing at room temperature for more than 24 hours, eliminating the need for additional heating and baking equipment. This significantly shortens the production cycle and reduces energy consumption, while also reducing quality instability caused by fluctuations in ambient temperature and humidity, thus improving production efficiency and product qualification rate.

[0042] In some embodiments, the ambient temperature for spraying can be configured to 25°C, the relative humidity can be configured to 60%, and the curing time can be configured to 24h to 48h.

[0043] The substrate is an organic polymer substrate wall panel and / or base plate for prefabricated kitchens and bathrooms; the prefabricated kitchen and bathroom includes multiple vertically arranged wall panels, base plates and pins, with matching mounting grooves and fixing holes for mounting pins on the side walls of adjacent wall panels, and grooves for mounting wall panels provided around the base plate.

[0044] More specifically, the wall panels are connected to each other by inserting pins into fixing holes. The lower end of the wall panel is embedded in the grooves around the base plate, forming a stable prefabricated kitchen and bathroom structure. The mounting grooves, fixing holes, and other grooves are key points for water leakage and stress concentration. By spraying a polyurea coating onto the entire prefabricated structure, a continuous and seamless waterproof and moisture-proof layer can be formed on the surface of the wall panels and base plate, as well as at each connection node. This effectively prevents moisture from seeping into the substrate from the assembly gaps, improving the overall sealing reliability and service life of the prefabricated kitchen and bathroom.

[0045] In some embodiments, the organic polymer substrate for the wall panels and base panels may be any one of PVC foam board, PE board, PP board or corresponding fiber-reinforced composite material board.

[0046] In step S3, for the inner surface of the wall panel, the total thickness of the polyurea coating is 2.0mm to 4.0mm; for the outer back surface of the wall panel, the total thickness of the polyurea coating is 0.5mm to 1.5mm; or for the grooved part of the base plate and the pin fixing hole part of the wall panel, before spraying the polyurea coating, a layer of polyurea coating is first applied to the groove surface and the inner wall of the hole as a base layer, and then the whole coating is sprayed.

[0047] More specifically, the inner surface of the wall panel is subjected to long-term washing, friction, and chemical detergent erosion. A thicker polyurea coating of 2.0mm to 4.0mm provides excellent scratch resistance, impact resistance, and moisture resistance. The outer back of the wall panel mainly serves a protective function, and a thinner polyurea coating of 0.5mm to 1.5mm is sufficient, thus saving material and reducing costs. For easily leaking nodes such as grooved areas of the base plate and pin fixing holes of the wall panel, since paint droplets cannot fully cover the groove walls and inner walls of the holes during spraying, applying a primer first can improve the coating coverage and sealing of these corners and vertical surfaces. When the overall spraying is carried out, the primer and the subsequent polyurea coating 107 form an integrated structure through chemical self-adhesion, ensuring the waterproof reliability of key nodes.

[0048] In summary: First, the surface of the prefabricated kitchen and bathroom substrate to be sprayed is cleaned and dried to remove oil and impurities, and the moisture content is controlled below 5%. Then, the substrate surface is sanded to achieve a surface roughness Ra of 3.2μm–6.3μm, and high-pressure air is used to remove loose dust. Next, an epoxy or polyurethane adhesion-promoting primer with 1%–5% silane coupling agent is applied to the roughened surface. The primer thickness is 20μm–50μm, and after drying... After the surface is dry, a primer layer is formed. Then, the A and B components of the two-component polyurea coating are preheated to 65℃~75℃ and 70℃~80℃ respectively, and mixed and atomized by a mixing spray gun at a spray pressure of 2000psi~3500psi. The coating is applied to the primer layer in 2 to 3 coats, with each coat being 0.5mm~1.5mm thick, forming a polyurea coating with a total thickness of 1.5mm~4.0mm. Finally, the coating is allowed to cure at room temperature for more than 24 hours to complete the construction.

[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A method for spraying a scratch-resistant and moisture-proof coating for prefabricated kitchens and bathrooms, characterized in that, Includes the following steps: Step S1: Perform pretreatment on the surface of the prefabricated kitchen and bathroom substrate to be sprayed. The pretreatment includes at least sanding to roughen the surface of the substrate. Step S2: Apply a primer to the pretreated substrate surface, wherein the primer is an adhesion-promoting primer; Step S3: Apply a two-component spray polyurea coating to the substrate surface with a primer. The A and B components of the two-component polyurea coating are preheated and then mixed and atomized for spraying to form a polyurea coating. The spraying is done in a multi-layer spraying method. Step S4: Curing the polyurea coating.

2. The method for spraying a prefabricated kitchen and bathroom scratch-resistant and moisture-proof coating according to claim 1, characterized in that, The pretreatment also includes cleaning and drying. The cleaning uses organic solvents to remove oil and impurities from the substrate surface, and the drying makes the moisture content of the substrate surface less than 5%.

3. The method for spraying a prefabricated kitchen and bathroom scratch-resistant and moisture-proof coating according to claim 2, characterized in that, The grinding process brings the surface roughness Ra of the substrate to 3.2μm to 6.3μm. After grinding, high-pressure air is used to blow away the surface dust.

4. The method for spraying a prefabricated kitchen and bathroom scratch-resistant and moisture-proof coating according to claim 1, characterized in that, The primer is an epoxy primer or a polyurethane primer, and the primer contains 1% to 5% silane coupling agent by weight of the total primer.

5. The method for spraying a prefabricated kitchen and bathroom scratch-resistant and moisture-proof coating according to claim 4, characterized in that, The primer is sprayed to a thickness of 20μm to 50μm. After the primer is applied, it is left to dry at room temperature for 30min to 120min, or baked at 40℃ to 60℃ for 10min to 30min to achieve a surface dry state.

6. The method for spraying a prefabricated kitchen and bathroom scratch-resistant and moisture-proof coating according to claim 1, characterized in that, In step S3, component A is preheated to 65°C to 75°C, component B is preheated to 70°C to 80°C, and the spraying pressure is 2000 psi to 3500 psi.

7. The method for spraying a prefabricated kitchen and bathroom scratch-resistant and moisture-proof coating according to claim 6, characterized in that, The multi-layer spraying is done in 2 to 3 coats, with each coat having a thickness of 0.5 mm to 1.5 mm and a total design thickness of 1.5 mm to 4.0 mm.

8. The method for spraying a prefabricated kitchen and bathroom scratch-resistant and moisture-proof coating according to claim 7, characterized in that, The spraying environment temperature in step S3 is 10℃~35℃, and the relative humidity is less than 85%; in step S4, the curing method is to let it stand at room temperature for more than 24 hours.

9. The method for spraying a prefabricated kitchen and bathroom scratch-resistant and moisture-proof coating according to claim 1, characterized in that, The substrate is an organic polymer substrate wall panel and / or base plate for prefabricated kitchens and bathrooms; the prefabricated kitchen and bathroom includes multiple vertically arranged wall panels, base plates and pins, with matching mounting grooves and fixing holes for mounting pins on the side walls of adjacent wall panels, and grooves for mounting wall panels provided around the base plate.

10. The method for spraying a prefabricated kitchen and bathroom scratch-resistant and moisture-proof coating according to claim 9, characterized in that, In step S3, the total thickness of the polyurea coating is 2.0mm to 4.0mm for the inner surface of the wall panel; the total thickness of the polyurea coating is 0.5mm to 1.5mm for the outer back surface of the wall panel; or for the grooved part of the base plate and the pin fixing hole part of the wall panel, before spraying the polyurea coating, a layer of polyurea coating is first applied to the groove surface and the inner wall of the hole as a base layer, and then the whole coating is sprayed.

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