A protective treatment method for the paint spraying of copper mesh regions on composite surfaces

Abstract

The application provides a protective treatment method for a copper mesh region of a composite material surface, comprising the following steps: S1. After curing and demolding of a composite material substrate, roughening treatment is performed on the surface of the substrate, and the surface is cleaned; S2. A bottom adhesive film is bonded to the copper mesh bonding region of the substrate, and room temperature compaction is performed to tightly bond the bottom adhesive film to the substrate; S3. A metal copper mesh is laid on the surface of the bottom adhesive film, and room temperature compaction is performed to tightly bond the copper mesh to the bottom adhesive film; S4. A surface adhesive film is laid on the surface of the metal copper mesh, and room temperature compaction is performed to tightly bond the surface adhesive film to the copper mesh; S5. The substrate, the bottom adhesive film, the copper mesh and the surface adhesive film are co-cured, and a rough structure meeting the paint adhesion requirement is formed on the surface of the surface adhesive film after curing; and S6. The surface adhesive film is polished, surface nubs and wrinkle defects are removed, and the surface is cleaned, and the metal copper mesh does not need to be polished.

Description

Technical Field

[0001] This application belongs to the field of composite material surface treatment technology, and in particular relates to a protective treatment method for spraying paint on the copper mesh area of ​​a composite material surface. Background Technology

[0002] Composite materials are widely used in aerospace, electronics, and automotive manufacturing due to their lightweight, high strength, and corrosion resistance. However, in some applications, composite material surfaces need to be bonded or integrated with copper mesh to achieve specific functions such as electromagnetic shielding and conductive paths.

[0003] After the copper mesh is bonded, the entire surface of the composite material needs to be painted. In existing technologies, to ensure the adhesion between the paint film and the copper mesh and the surface of the composite material, the surface of the copper mesh usually needs to be roughened by grinding. However, the copper mesh itself is thin and fragile, and physical damage such as wire breakage and deformation can easily occur during grinding, reducing its conductivity and service life. Moreover, after the copper mesh is damaged, conductive adhesive is required to fill the gaps and an electromagnetic repair coating is applied to restore its electrical conductivity. This process is not only cumbersome and difficult to operate, but also leads to low production efficiency and increases the material costs of conductive adhesive and electromagnetic repair coating, seriously affecting the production schedule and manufacturing cost control. Summary of the Invention

[0004] Purpose of the invention: The present invention aims to solve the following problems existing in the prior art: the grinding and roughening process damages the surface of the metal copper mesh, affecting its functionality; additional conductive adhesive or electromagnetic repair coating is required for repair, which increases cost and complexity; the process efficiency is low and it is difficult to meet the needs of large-scale production.

[0005] This application provides a protective treatment method for spraying paint on the copper mesh area of ​​a composite material surface, the method comprising: Step S1. After the composite material substrate has cured and been demolded, its surface is roughened by grinding and cleaned. Step S2. Adhere the bottom adhesive film to the copper mesh bonding area of ​​the substrate and press it at room temperature to ensure that the bottom adhesive film adheres tightly to the substrate. Step S3. Lay a layer of copper mesh on the surface of the bottom adhesive film and press it at room temperature to ensure that the copper mesh adheres tightly to the bottom adhesive film; Step S4. Lay a layer of surface adhesive film on the surface of the copper mesh and press it at room temperature to ensure that the surface adhesive film adheres tightly to the copper mesh; Step S5. The substrate, the bottom adhesive film, the copper mesh and the top adhesive film are cured together, and the surface of the cured top adhesive film forms a rough structure that meets the requirements of paint adhesion. Step S6. Polish the surface adhesive film to smooth it, remove surface nodules and wrinkles, and clean it thoroughly. There is no need to polish the metal copper mesh.

[0006] Preferably, in step S1, 120#~240# sandpaper is used for sanding, anhydrous ethanol or a special cleaning agent for composite materials is used for cleaning, and the drying time is not less than 15 minutes. After drying, there is no oil or dust residue on the surface of the substrate.

[0007] Preferably, in step S2, the bottom adhesive film is an epoxy resin film with a thickness of 0.05mm to 0.1mm.

[0008] Preferably, in step S3, the thickness of the copper mesh is 0.05mm to 0.2mm.

[0009] Preferably, in step S4, the surface adhesive film is a modified epoxy resin film or a modified polyurethane film with a thickness of 0.05 mm to 0.1 mm.

[0010] Preferably, in step S6, the polishing is done with 240#~400# sandpaper, the coating material is polyurethane, epoxy resin, or silicone, the coating thickness is 0.05mm~0.07mm, and the curing period is 80℃×2h.

[0011] Preferably, step S5 includes: Curing: The bonded composite material parts are fed into the curing equipment and cured according to the preset curing parameters, so that the composite material, the bottom adhesive film, the copper mesh and the surface adhesive film form an integrated and stable structure. After curing, the rough structure on the surface of the adhesive film forms the roughened interface required for painting, and at the same time, the adhesive film forms a dense protective layer to wrap the copper mesh.

[0012] Preferably, step S6 includes: Spray painting: Spray paint the area of ​​the metal copper mesh coated with adhesive film; since the microstructure of the adhesive film surface significantly improves the adhesion between the paint layer and the copper mesh, only the surface of the adhesive film needs to be polished smooth, and no additional polishing is required on the surface of the copper mesh.

[0013] The beneficial technical effects of this application are as follows: (1) Protect the surface of the metal copper mesh and avoid damage from grinding, thereby increasing the material utilization rate to over 98%; (2) The roughening effect is achieved through the microstructure of the adhesive film surface, which improves the adhesion and uniformity of the spray painting process; (3) The process is simplified, and the cost of materials such as conductive adhesive and electromagnetic repair coating is eliminated, resulting in a 40% to 60% reduction in overall cost; (4) The process is simple, efficient and low cost. It is suitable for composite material surfaces of various shapes and sizes. Only the adhesive film bonding and curing process needs to be added. No additional special equipment is required, and the production efficiency is increased by more than 30%. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a process flow diagram provided in the embodiments of this application; Figure 2 This is a structural schematic diagram provided in an embodiment of this application. Detailed Implementation

[0016] The following describes the embodiments and appendices. Figure 1 -Appendix Figure 2 The present invention will be described in further detail, but the embodiments of the present invention are not limited thereto.

[0017] The purpose of this invention is to address the problems in the prior art where grinding and roughening the copper mesh area on the surface of composite materials before painting easily damages the copper mesh, resulting in high repair costs and low efficiency. This invention provides a protective treatment method that can achieve a roughening effect without grinding and simultaneously protect the copper mesh, simplifying the process, reducing costs, and improving production efficiency.

[0018] This invention provides a protective treatment method for spraying paint on the copper mesh area of ​​a composite material surface, characterized by comprising the following steps: (1) Surface preparation: After the composite material part is demolded, use 120# sandpaper to sand the skin surface of the metal copper mesh bonding area to remove the resin gloss, but do not damage the fibers. Then use a vacuum cleaner to remove the dust, and then use clean medical gauze dipped in industrial acetone to wipe the bonding surface until there is no dust or dirt, and let it dry for no less than 10 minutes.

[0019] (2) Bonding of the bottom layer adhesive film: Select a bottom layer adhesive film that has good compatibility with both the composite material substrate and the copper mesh, flatten it and bond it to the copper mesh area to be bonded on the surface of the substrate that has been polished. Ensure that the adhesive film and the substrate are free of bubbles and curling edges by room temperature compaction, and form a tight bond to form a bottom layer protection and bonding transition layer.

[0020] (3) Metal copper mesh bonding: The metal copper mesh is laid on the surface of the bottom adhesive film. The boundary of the copper mesh is required to be consistent with the boundary of the bottom adhesive film. The copper mesh is pressed at room temperature to ensure tight bonding with the bottom adhesive film and the substrate.

[0021] (4) Surface adhesive film bonding: A protective adhesive film is uniformly bonded to the surface of the copper mesh. This adhesive film has good conductivity and corrosion resistance, and its surface has a micro-rough structure. During the bonding process, ensure that the adhesive film is completely adhered to the surface of the copper mesh, and that the adhesive film completely covers the surface of the copper mesh. The adhesive film is compacted at room temperature to ensure that it is completely adhered to the copper mesh without bubbles, curling edges, or wrinkles.

[0022] (4) Curing: The bonded composite material parts are fed into the curing equipment and cured according to the preset curing parameters, so that the composite material-bottom adhesive film-copper mesh-top adhesive film form an integrated and stable structure. After curing, the rough structure on the surface of the adhesive film forms the roughened interface required for painting, and at the same time, the adhesive film forms a dense protective layer to wrap the copper mesh.

[0023] (5) Spray painting: Spray paint the area of ​​the metal copper mesh coated with adhesive film. Since the microstructure of the adhesive film surface can significantly improve the adhesion between the paint layer and the copper mesh, it is only necessary to polish the surface of the adhesive film to a smooth finish, and no additional polishing is required on the surface of the copper mesh.

[0024] The surface adhesive film combines physical protection and surface roughening into one, replacing the traditional sanding and roughening process. It provides a protective layer for sanding before painting without requiring additional roughening of the copper mesh, thus solving the problem of traditional sanding inevitably damaging the copper mesh.

[0025] By integrating multiple collaborative processes such as adhesive film bonding, copper mesh laying, curing, and surface roughening, the traditional solutions eliminate the need for copper mesh grinding, conductive adhesive repair, and electromagnetic repair coating repair, significantly shortening the production cycle and improving process efficiency.

[0026] The adhesive film bonding process is simple and compatible with existing production processes.

[0027] Technological innovation: Breaking through the traditional process of "first gluing the copper mesh and then polishing the whole thing", we proposed an integrated approach that replaces polishing with adhesive film, achieving the simultaneous completion of copper mesh protection and surface roughening for the first time, and resolving the contradiction in the traditional process that "roughening will inevitably damage the copper mesh".

[0028] Material and Function Integration Innovation: The surface film integrates both protective and roughening functions, meeting the paint adhesion requirements without additional sanding.

[0029] Innovative structural design: The "bottom layer adhesive film + copper mesh + surface adhesive film" structure not only achieves full protection of the copper mesh, but also forms an integrated structure through synergistic curing, avoiding the risk of interlayer delamination, while improving the overall mechanical performance stability and surface consistency of the part.

[0030] Process simplification and innovation: The process flow is greatly simplified, eliminating many steps in the traditional solution, such as copper mesh grinding and roughening, damage detection, conductive adhesive repair, and electromagnetic repair coating spraying. The number of steps is reduced by more than 50%, significantly improving production efficiency.

[0031] This application protects the surface of the copper mesh from grinding damage, increasing material utilization to over 98%. It achieves a roughening effect through the microstructure of the adhesive film surface, improving the adhesion and uniformity of the paint spraying process. It simplifies the process flow, eliminating the need for conductive adhesives and electromagnetic repair coatings, resulting in a 40%–60% reduction in overall cost. The process is simple, efficient, and low-cost, suitable for composite material surfaces of various shapes and sizes. Only the adhesive film bonding and curing steps are required, without the need for additional specialized equipment, increasing production efficiency by over 30%.

[0032] An implementation example is taken of a frequency-selective radome of a certain aircraft model. The method of this invention is used for processing, and the specific implementation steps are as follows: Step 1: Surface Preparation After the frequency-selective composite has cured and been demolded, use 120# sandpaper to sand the skin surface of the metal copper mesh bonding area to remove the resin gloss, but without damaging the fibers. Then use a vacuum cleaner to remove dust, and then use clean medical gauze dipped in industrial acetone to wipe the bonding surface until it is free of dust and dirt, and let it air dry for no less than 30 minutes.

[0033] Step 2: Bonding the bottom adhesive film Select a 0.1mm thick epoxy resin base film and lay it on the copper mesh bonding area on the composite surface. After the film is laid, lay a perforated release film and coated cloth on the film surface, then cover it with a breathable felt cover of appropriate size, and seal the vacuum bag with vacuum bag film and sealing strip. Connect the vacuum system and compact it at room temperature for no less than 30 minutes under a vacuum degree of not less than 0.080MPa. After compaction, the film and the substrate are tightly bonded and flat, without bubbles, curling edges, etc.

[0034] Step 3: Copper Mesh Installation Select a copper mesh with a width of 600mm and a thickness of 0.1mm. Lay the copper mesh on the surface of the underlying adhesive film, ensuring that the laying boundary of the copper mesh is consistent with the laying boundary of the underlying adhesive film. Ensure that the copper mesh is tightly bonded to the underlying adhesive film and substrate by room temperature compaction, and ensure that there are no curling edges, bulges or other defects in the copper mesh.

[0035] Step 4: Surface adhesive film bonding Select a 0.1mm thick epoxy resin surface film and apply it to the surface of the copper mesh. The film should be completely adhered to the surface of the copper mesh and completely cover the surface of the copper mesh. Compact the film at room temperature to ensure that the film is completely adhered to the copper mesh without bubbles, curling edges, or wrinkles.

[0036] Step 5, Curing Lay a clean layer of coated cloth over the copper mesh area, leaving a 20mm-25mm margin at the edges, and secure it with pressure-sensitive adhesive tape. Then, lay a non-porous release film on the surface. The coated cloth and release film should be laid flat and wrinkle-free, with an overlap of 10mm-15mm allowed at the seams. The release film should extend at least 30mm beyond the edge of the adhesive film. Next, lay a layer of breathable felt and seal the vacuum bag film with adhesive strips. Place it in an oven, connect it to the vacuum system, and cure it according to the preset curing parameters. Step 6: Spray painting Sand the copper mesh area smooth with 180# or finer sandpaper. Use an all-purpose cloth dampened with acetone or ethyl acetate to remove any debris and impurities from the sanding process that could affect the coating, ensuring the surface of the composite material is clean. Prepare and mature the epoxy polyamide varnish according to the mixing requirements, then pour it into the spray gun. Adjust the spraying parameters and spray the copper mesh surface. After spraying, cure at room temperature or in an oven only.

[0037] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A method for protective treatment of copper mesh areas on the surface of a composite material by spraying paint, characterized in that, The method includes: Step S1. After the composite material substrate has cured and been demolded, its surface is roughened by grinding and cleaned. Step S2. Adhere the bottom adhesive film to the copper mesh bonding area of ​​the substrate and press it at room temperature to ensure that the bottom adhesive film adheres tightly to the substrate. Step S3. Lay a layer of copper mesh on the surface of the bottom adhesive film and press it at room temperature to ensure that the copper mesh adheres tightly to the bottom adhesive film; Step S4. Lay a layer of surface adhesive film on the surface of the copper mesh and press it at room temperature to ensure that the surface adhesive film adheres tightly to the copper mesh; Step S5. The substrate, the bottom adhesive film, the copper mesh and the top adhesive film are cured together, and the surface of the cured top adhesive film forms a rough structure that meets the requirements of paint adhesion. Step S6. Polish the surface adhesive film to smooth it, remove surface nodules and wrinkles, and clean it thoroughly. There is no need to polish the metal copper mesh.

2. The method according to claim 1, characterized in that, In step S1, sanding is done with 120#~240# sandpaper, cleaning is done with anhydrous ethanol or a special cleaning agent for composite materials, and the drying time is no less than 15 minutes. After drying, there is no oil or dust residue on the surface of the substrate.

3. The method according to claim 1, characterized in that, In step S2, the bottom layer adhesive film is an epoxy resin film with a thickness of 0.05mm to 0.1mm.

4. The method according to claim 1, characterized in that, In step S3, the thickness of the copper mesh is 0.05mm~0.2mm.

5. The method according to claim 1, characterized in that, In step S4, the surface adhesive film is a modified epoxy resin film or a modified polyurethane film with a thickness of 0.05mm to 0.1mm.

6. The method according to claim 1, characterized in that, In step S6, the polishing is done using 240#~400# sandpaper, the coating material is polyurethane, epoxy resin, or silicone, the coating thickness is 0.05mm~0.07mm, and the curing period is 80℃×2h.

7. The method according to claim 1, characterized in that, Step S5 includes: Curing: The bonded composite material parts are fed into the curing equipment and cured according to the preset curing parameters, so that the composite material, the bottom adhesive film, the copper mesh and the surface adhesive film form an integrated and stable structure. After curing, the rough structure on the surface of the adhesive film forms the roughened interface required for painting, and at the same time, the adhesive film forms a dense protective layer to wrap the copper mesh.

8. The method according to claim 1, characterized in that, Step S6 includes: Spray painting: Spray paint the area of ​​the metal copper mesh coated with adhesive film; since the microstructure of the adhesive film surface significantly improves the adhesion between the paint layer and the copper mesh, only the surface of the adhesive film needs to be polished smooth, and no additional polishing is required on the surface of the copper mesh.

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