Method for spraying powder on surface of thermosetting non-metal composite material workpiece

Abstract

The invention relates to a method for performing powder spraying on the surface of a thermosetting non-metal composite material workpiece. The method comprises the following steps: S1, pretreating a substrate; s2, screening is carried out; s3, polishing is conducted; s4, preliminary drying and exhausting; s5, pasting a conductive adhesive tape; s6, preheating before substrate spraying; s7, spraying conductive powder; s8, performing high-temperature curing on the conductive powder; s9, spraying color powder; s10, performing high-temperature curing on the color powder; s11, transparent powder is sprayed; s12, drying is conducted; s13, inspection is carried out; and S14, warehousing and storing. According to the method for spraying the powder on the surface of the thermoset non-metal composite material workpiece, the final yield of recollecting and using the powder can reach 95%, the tail gas treatment cost is reduced, the labor cost is reduced, and finally the overall cost is reduced to 60% of that of paint spraying.

Description

Technical Field

[0001] This invention relates to the technical field of spraying methods, and in particular to a method for applying powder coating to the surface of thermosetting non-metallic composite workpieces. Background Technology

[0002] The surface color spraying of existing thermosetting non-metallic composite parts mainly adopts the method of paint spraying. Because the paint itself releases solvent VOCs, toxic additives are added to increase the paint adhesion. During the spraying process, the paint itself evaporates, and the adhesion problem causes the paint to fall off, resulting in waste due to repeated repainting. Once the paint sprayed on the workpiece falls to the ground, it can only be scrapped and cannot be reused, making the paint utilization rate only 30%-70%. The wastewater and exhaust gas generated during the spraying process need to be treated. Summary of the Invention

[0003] The technical problem to be solved by this invention is as follows: In order to solve the problems existing in the background technology, this invention provides a method for powder coating on the surface of thermosetting non-metallic composite workpieces. Because the material is a colored powder, there are no VOCs caused by volatilization. Because of its different film-forming method, there is no need to add traditional toxic additives to increase adhesion. Also, because of the different film-forming method, no touch-up painting is required after the coating is completed. Because the powder can be recycled through a circulation system to collect and reuse the powder that falls on the ground, the final utilization rate can reach 95%. Moreover, this powder coating technology does not produce exhaust gas emissions due to volatilization during the coating process, reducing exhaust gas treatment costs. By improving the utilization rate of the material itself and optimizing the material process, labor costs are reduced, and the overall cost is reduced to 60% of that of paint coating.

[0004] The technical solution adopted by this invention to solve its technical problem is: a method for powder coating on the surface of a thermosetting non-metallic composite material workpiece, comprising the following steps: S1, substrate pretreatment; S2, screening; S3, grinding; S4, preliminary drying and venting; S5, applying conductive tape; S6, preheating the substrate before coating; S7, spraying conductive powder; S8, high-temperature curing of conductive powder; S9, spraying colored powder; S10, high-temperature curing of colored powder; S11, spraying transparent powder; S12, drying; S13, inspection; S14, warehousing.

[0005] Further specifying, in the above technical solution, the S4 preliminary drying and exhaust involves placing the workpiece on the hanger into the drying chamber, setting the oven temperature to 150℃-190℃, and continuously baking for 180 minutes.

[0006] Further specifying, in the above technical solution, the preheating before S6 substrate spraying is as follows: the workpiece on the hanger is placed in a drying room, which requires the spray booth to be made of metal and grounded, and the workpiece is suspended in the air with the hook on the spray booth, with the lowest point of the workpiece being more than 20 centimeters off the ground.

[0007] Further specifying, in the above technical solution, the S7 conductive powder spraying: the conductive powder is sprayed, the spraying tool needs to be 20-30cm away from the workpiece, the spray gun is moved at a uniform speed to ensure that the conductive powder evenly covers the entire surface of the workpiece, and the spraying thickness is controlled at 60-80μm.

[0008] Further specifying, in the above technical solution, the S11 transparent powder coating: the transparent powder is uniformly sprayed using electrostatic spraying, and the coating thickness is controlled at 60-100μm.

[0009] To further specify, in the above technical solution, the S10 color powder is cured at high temperature by pushing the workpiece on the hanger into the drying room, where the temperature is 110°C for preheating.

[0010] Further specifying the technical solution above, S13, inspection: In the inspection room, the appearance must not have discoloration, uneven spraying, mixed colors, runs, peeling, cracks, missing paint, exposed substrate, indentations, fisheyes, or pinhole defects; impurities, particles, oil spots, and pinholes: Area A of the paint film is allowed to have: same-color particles (impurities) with a diameter d < 0.5mm, and pinholes (oil spots) are not allowed; no more than 3 particles are allowed within 400mm, and same-color particles with a diameter > 0.5mm and particles of any size with different colors (impurities) are not allowed; dense particles within 400×400mm of the paint film surface are not allowed: Area A < Φ0.5×3; single particle: Area A ≤ 0.5mm. Adhesion 2mm ≤ Grade 1; film thickness: ≥ 50um.

[0011] Further specifying, in the above technical solution, the S1 substrate pretreatment includes the following steps: S11, loading; S22, degreasing; S33, first water wash; S44, second water wash; S55, second water wash; S66, fresh pure water wash; S77, blowing dry; S88, drying.

[0012] The beneficial effects of this invention are as follows: The method for powder coating on the surface of thermosetting non-metallic composite workpieces proposed in this invention does not involve the addition of traditional toxic additives to increase adhesion because the material is a colored powder and there are no VOCs caused by volatilization. Also, because of the different film-forming method, no touch-up painting is required after the coating is completed. The powder can be recycled through a circulation system to collect and reuse the powder that falls on the ground, with a final utilization rate of up to 95%. Furthermore, this powder coating technology does not produce exhaust gas emissions due to volatilization during the coating process, reducing exhaust gas treatment costs. By improving the utilization rate of the material itself and optimizing the material process, labor costs are reduced, ultimately reducing the overall cost to 60% of that of paint spraying. Attached Figure Description

[0013] 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. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the process structure of the present invention. Detailed Implementation

[0015] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0016] See Figure 1 This is a method for powder coating on the surface of thermosetting non-metallic composite materials, comprising the following steps: S1, substrate pretreatment; S2, screening; S3, grinding; S4, preliminary drying and venting; S5, applying conductive tape; S6, preheating the substrate before coating; S7, spraying conductive powder; S8, high-temperature curing of conductive powder; S9, spraying colored powder; S10, high-temperature curing of colored powder; S11, spraying transparent powder; S12, drying; S13, inspection; S14, warehousing.

[0017] The process includes: S4 Preliminary Drying and Exhausting: Place the workpiece on the hanger into the drying chamber, set the oven temperature to 150℃-190℃, and bake for 180 minutes. S6 Preheating Before Substrate Spraying: Place the workpiece on the hanger in the drying chamber (the chamber must be made of metal and grounded), with the workpiece suspended above the ground at least 20 cm above the ground. S7 Spraying Conductive Powder: Spray conductive powder, maintaining a 20-30 cm distance between the spraying tool and the workpiece. Move the spray gun at a uniform speed to ensure even coverage of the entire workpiece surface, with a spray thickness of 60-80 μm. S11 Spraying Transparent Powder: Apply transparent powder evenly using electrostatic spraying, with a spray thickness of 60-100 μm. S10 High-Temperature Curing of Colored Powder: Push the workpiece on the hanger into the drying chamber, preheating it to 110℃. S13. Inspection: In the inspection room, the following defects are not permitted in terms of appearance: discoloration, uneven spraying, discoloration, runs, peeling, cracks, missing paint, exposed substrate, indentations, fisheyes, and pinholes. Impurities, particles, oil spots, and pinholes: In area A of the paint film, the following are permitted: particles of the same color (impurities) with a diameter d < 0.5 mm; pinholes (oil spots) are not permitted; no more than 3 particles are permitted within 400 mm; particles of the same color with a diameter > 0.5 mm and particles of any different color (impurities) of any size are not permitted. Dense particles within 400×400 mm of the paint film surface are not permitted: Area A < Φ0.5×3; Single particle: Area A ≤ 0.5 mm. Adhesion: 2 mm ≤ Grade 1; Film thickness: ≥ 50 μm. S1 Substrate Pretreatment: Includes the following steps: S11, Loading the workpiece; S22, Degreasing; S33, First wash; S44, Second wash; S55, Second wash; S66, Fresh pure water wash; S77, Blow-dry; S88, Dry.

[0018] See Figure 1The thermosetting non-metallic composite material workpiece to be sprayed is hung on the fixture in step one and then pushed into the degreasing tank in step two for degreasing. The temperature of the degreasing tank should be controlled not to exceed 120℃. The workpiece is immersed for 10-15 minutes, and the conductivity is >100us / cm to remove grease from the surface of the parts. After that, the parts are removed from the degreasing tank in step two and pushed into the cleaning tank in step three for the first cleaning. The cleaning solution should have a pH of 5-9 and a conductivity <330us / cm. After cleaning, the parts are removed and pushed into the cleaning tank in step four. The cleaning solution should have a pH of 6-9 and a conductivity <55us / cm. After cleaning, the parts are removed and pushed into the pure water tank in step five. The pure water should have a pH of 6-9 and a conductivity <20us / cm. After cleaning, the parts are removed and pushed into the pure water tank in step six. The pure water should have a pH of 5-8 and a conductivity < Clean the surface with a water flow rate of 10 μS / cm and a flow rate of 600-1800 LH. After cleaning, remove the product from the pure water tank and proceed to step seven, where a fan with a frequency of 30-40 Hz is used to dry the surface. After drying, push the product into the drying room in step eight. The drying room requires a drying temperature of 75-90 degrees Celsius for 40 minutes. Then, send the product to the inspection room in step nine for visual inspection. After inspection, send the parts with good surface quality to the drying room in step eleven. For qualified parts with only minor scratches and small area defects, use 400-grit sandpaper to gently sand along the texture of the substrate. Apply even pressure during sanding to avoid scratching the substrate and ensure that the surface of the workpiece is flat and smooth. After grinding, use dry compressed air to blow along the surface of the workpiece to thoroughly remove the dust generated during grinding, preventing dust residue from affecting the spraying effect. After that, send it to the drying room in step eleven. Set the oven temperature to 150℃-190℃ and bake for 180 minutes to remove internal gases and residual small volatile molecules from the workpiece, preventing defects such as bubbles, pinholes, and shrinkage cavities. At the same time, clean the special hanger for the workpiece in step twelve, exposing the surface metal substrate. Then, attach the special conductive tape from step thirteen to the exposed metal surface of the hanger. Hang the workpiece processed in step eleven onto the special hanger processed in step twelve. Following the requirements of step fifteen, attach the conductive tape from step twelve to the back of the workpiece. After that, send the hanger and workpiece into the spray booth in step sixteen. The spray booth should be made of metal and grounded. The workpiece should be suspended with the hook on the spray booth, with the bottom end at least 20 cm off the ground. Then, spray conductive powder. During spraying, the spraying tool should be kept 20-30 cm away from the workpiece. Maintain a constant distance and speed when moving the spray gun to ensure that the conductive powder evenly covers the entire surface of the workpiece. Control the coating thickness to 40-80μm, avoiding any missed areas or drips. Traditional spraying techniques require the addition of water curtains or other equipment in the spray booth to absorb irritating gases during the spraying process and protect the health of personnel.The new thermosetting non-metallic material spraying technology eliminates the need for water curtains and other equipment, reducing energy consumption and spraying costs. Traditional spraying requires leveling, followed by sanding with 600-grit sandpaper. The newly proposed non-metallic color part spraying technology eliminates this step. After spraying, the workpiece is placed in the drying chamber (step seventeen) at a set temperature of 160℃-180℃ for 20 minutes to melt and solidify the surface powder. Following the requirements of step eighteen, the workpiece is preheated to 100℃. The workpiece is then placed on a hanger in the drying chamber, which must be made of metal and grounded. The workpiece is suspended, with its lowest point at least 20 cm off the ground. Conductive powder is then sprayed. During spraying, the spraying equipment must maintain a distance of 20-30 cm from the workpiece and move at a uniform speed. The spray gun ensures that the conductive powder evenly covers the entire surface of the workpiece, with the coating thickness controlled at 60-80μm. Traditional spraying techniques require the addition of water curtains or other equipment in the spray booth to absorb irritating gases during the spraying process and protect the health of personnel. The new thermosetting non-metallic material spraying technology does not require water curtains or other equipment, reducing energy consumption and spraying costs. Furthermore, traditional spraying requires leveling after completion, followed by sanding with 600-grit sandpaper to achieve a smooth finish. The newly proposed non-metallic color part spraying technology eliminates this step. After spraying, the workpiece is transferred to the drying oven in step 20 and baked at a constant temperature of 160℃ for 20 minutes. This allows the conductive primer layer cured in step 17 to undergo an electrical reaction, forming a uniform and dense color paint layer. The color deviation Δ of the color paint layer is then measured. For E≤1.5, traditional spraying technology requires the addition of water curtains or other equipment in the spray booth to absorb irritating gases during the spraying process and protect the health of personnel. The new thermosetting non-metallic material spraying technology eliminates the need for water curtains, reducing energy consumption and spraying costs. Furthermore, traditional spraying requires leveling and subsequent sanding with 600-grit sandpaper after leveling; the newly proposed non-metallic color part spraying technology eliminates this step. After testing, the workpiece is placed in the drying chamber in step twenty-one, requiring preheating at 110 degrees Celsius. After preheating, the workpiece is re-hung in the spray booth in step twenty-two, where a transparent powder is evenly sprayed using electrostatic spraying, with the spray thickness controlled at 60-100 μm. Traditional spraying technology requires water curtains or other equipment in the spray booth to absorb irritating gases during the spraying process. To prevent harm to personnel and ensure their health, the new thermosetting non-metallic material spraying technology eliminates the need for water curtains and other equipment, reducing energy consumption and spraying costs. Traditional spraying requires leveling, followed by sanding with 600-grit sandpaper. The newly proposed non-metallic color part spraying technology eliminates this step. After spraying, the material is placed in the drying room in step twenty-three and baked at a constant temperature of 160℃ for 20 minutes to melt and solidify the transparent powder into a transparent clear varnish layer. It is then removed and transferred to the inspection room in step twenty-four. Visually, defects such as discoloration, uneven spraying, discoloration, runs, peeling, cracks, missing paint, exposed substrate, indentations, fisheyes, and pinholes are not permitted. Impurities, particles, oil spots, and pinholes are also acceptable. In area A of the paint film, the diameter of same-color particles (impurities) d < 0.5mm is permitted.Pinholes (oil spots) are not allowed; no more than 3 are allowed within 400mm. No particles of the same color with a diameter >0.5mm or any size of discolored particles (impurities) are allowed. Dense particles within 400×400mm of the paint film surface are not allowed: Area A < Φ0.5×3; Single particle: Area A ≤ 0.5mm. Adhesion: 2mm ≤ Grade 1; Film thickness: ≥50um. After meeting the requirements, it is placed on the special equipment in step twenty-five and transported to the warehouse for storage. Traditional spraying technology requires the treatment of hazardous waste generated during the spraying process, such as wastewater, after spraying. However, the newly proposed thermosetting non-metallic material spraying technology does not generate hazardous waste as in traditional spraying technology, thus reducing costs.

[0019] Existing thermosetting non-metallic paint spraying technologies suffer from the problem that the paint itself is a solution and therefore volatile, resulting in a large amount of paint mist and VOCs, which pollutes and endangers the health of operators. During the spraying process, the paint can only be sprayed using pressure spraying technology, which causes it to evaporate rapidly, generating a large amount of paint mist and VOCs. To protect the health of personnel, water curtains and masks are required to prevent the inhalation of harmful substances. However, the use of water curtain technology results in a large amount of paint mist and VOCs being adsorbed into the water, generating wastewater. In contrast, the thermosetting non-metallic paint spraying technology proposed in this application does not generate a large amount of paint mist due to evaporation because the material itself is a powder, and it will not cause pollution from VOCs that endanger the health of operators. The new thermosetting non-metallic paint spraying technology eliminates the need for operators to wear masks to prevent powder inhalation during spraying, ensuring their health. It also reduces pollution by eliminating wastewater and waste residue. Existing thermosetting non-metallic paint spraying technologies suffer from low utilization rates (30%-60%) due to paint evaporation, adhesion issues arising from varying spray locations, and the need for multiple coats for leveling. The newly proposed technology, however, utilizes a powdered spraying material, eliminating evaporation issues and significantly improving paint utilization. Negative pressure decoration can achieve the recycling of sprayed powder, thereby improving the utilization rate of materials. Due to its different molding method, it only needs to be sprayed once and does not require multiple spraying and touch-up. Ultimately, its utilization rate can reach more than 95%. Thermosetting non-metallic parts paint spraying technology has a complex process that requires multiple spraying and leveling treatments on the surface. Moreover, the paint utilization rate is low and exhaust gas treatment is required, which increases the cost of hazardous waste treatment. Due to its low paint utilization rate and high hazardous waste treatment costs, its spraying cost is high. However, the thermosetting non-metallic parts paint spraying technology of this application has achieved a cost reduction of 60% compared to paint spraying due to its own technical optimization.

[0020] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for applying powder coating to the surface of a thermosetting non-metallic composite workpiece, characterized in that: The process includes the following steps: S1, substrate pretreatment; S2, screening; S3, sanding; S4, initial drying and degassing; S5, applying conductive tape; S6, preheating the substrate before spraying; S7, spraying conductive powder; S8, high-temperature curing of conductive powder; S9, spraying color powder; S10, high-temperature curing of color powder; S11, spraying transparent powder; S12, drying; S13, inspection; S14, warehousing.

2. The method for applying powder coating to the surface of a thermosetting non-metallic composite workpiece according to claim 1, characterized in that: The S4 preliminary drying and exhaust process involves placing the workpiece on the hanger into the drying chamber, setting the oven temperature to 150℃-190℃, and baking for 180 minutes.

3. The method for applying powder coating to the surface of a thermosetting non-metallic composite workpiece according to claim 1, characterized in that: The preheating before spraying the S6 substrate involves placing the workpiece on the hanger in a drying room. The spray room must be made of metal and grounded. The workpiece is suspended in the air with the bottom end at least 20 centimeters off the ground.

4. The method for applying powder coating to the surface of a thermosetting non-metallic composite workpiece according to claim 1, characterized in that: The S7 conductive powder spraying process involves spraying conductive powder. During spraying, the spraying tool must be kept 20-30cm away from the workpiece, and the spray gun must be moved at a uniform speed to ensure that the conductive powder evenly covers the entire surface of the workpiece. The spraying thickness is controlled at 60-80μm.

5. The method for applying powder coating to the surface of a thermosetting non-metallic composite workpiece according to claim 1, characterized in that: The S11 transparent powder coating: The transparent powder is uniformly sprayed using electrostatic spraying, and the coating thickness is controlled between 60-100μm.

6. The method for applying powder coating to the surface of a thermosetting non-metallic composite workpiece according to claim 1, characterized in that: The S10 color powder is cured at high temperature: the workpiece on the hanger is pushed into the drying room, and the drying room is preheated at a temperature of 110°C.

7. The method for applying powder coating to the surface of a thermosetting non-metallic composite workpiece according to claim 1, characterized in that: S13 Inspection: In the inspection room, the following defects are not permitted in terms of appearance: discoloration, uneven spraying, discoloration, runs, peeling, cracks, missing paint, exposed substrate, indentations, fisheyes, and pinholes. Impurities, particles, oil spots, and pinholes: In area A of the paint film, the following are permitted: particles (impurities) of the same color with a diameter d < 0.5 mm; pinholes (oil spots) are not permitted; no more than 3 particles are permitted within 400 mm; particles of the same color with a diameter > 0.5 mm and particles of any different color (impurities) of any size are not permitted. Dense particles within 400×400 mm of the paint film surface are not permitted: Area A < Φ0.5×3; Single particle: Area A ≤ 0.5 mm. Adhesion: 2 mm ≤ Grade 1; Film thickness: ≥ 50 μm.

8. The method for applying powder coating to the surface of a thermosetting non-metallic composite workpiece according to claim 1, characterized in that: The S1 substrate pretreatment includes the following steps: S11, loading the workpiece; S22, degreasing; S33, first water wash; S44, second water wash; S55, second water wash; S66, fresh pure water wash; S77, blowing dry; S88, baking.

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