Sand blasting coating for camera shell and preparation process of sand blasting coating

Abstract

The invention relates to the technical field of metal corrosion prevention, in particular to a sand blasting coating for a camera shell and a preparation process of the sand blasting coating. A preparation technology of a sand blasting coating for a camera shell comprises the following steps that a pretreated camera shell die casting is subjected to sand blasting treatment through an abrasive material, the camera shell die casting is soaked in phosphoric acid treatment liquid to be treated, a layer of organic coating is sprayed to the surface after the camera shell die casting is taken out, and a protective coating is formed; and finally, the sand blasting coating is formed through water vapor and curing treatment. According to the invention, sand blasting treatment and phosphoric acid treatment are combined, tiny pits and bulges formed by sand blasting increase the surface roughness and enhance the mechanical occlusal force, and an aluminum phosphate conversion film generated by phosphoric acid treatment fills surface micropores and cracks to form a large number of hydroxyl groups and other active sites which can react with functional groups in the organic coating, so that the organic coating has a good anti-corrosion effect. Covalent bonds or hydrogen bonds are formed, and the adhesive force between the organic coating and a base material is improved, so that the problems of surface defects and surface tension change are solved.

Description

Technical Field

[0001] The invention relates to the technical field of metal anticorrosion, and in particular to a sandblasting coating for a camera housing and a preparation process thereof. Background Art

[0002] The main function of the camera housing is to protect the precision optical and electronic components inside and prevent them from being damaged by the external environment. The housing is often formed by aluminum alloy die-casting. In addition, it is also responsible for fixing the lens and other components, ensuring the stability of image capture, and providing good electromagnetic shielding. For the selection of camera housings, alloy die-castings are widely used due to their high strength, good thermal conductivity and electromagnetic compatibility, and are especially suitable for applications that require durability and impact resistance. Compared with plastics, alloy die-castings are stronger, but they also face the risk of rust and corrosion, especially in humid environments. Therefore, in order to extend its service life and maintain the appearance quality, it is usually necessary to perform surface treatment, such as spray coating.

[0003] For aluminum alloy die-castings, the rust on the surface of the substrate is loose and porous, which will lead to a decrease in the adhesion of the coating. Continuous internal corrosion will cause the coating bubbles to fall off. At the same time, during the die-casting process, the residual gas in the mold cavity may cause bubble groups to appear on the surface of the casting, resulting in poor anti-corrosion effect. Therefore, surface treatment is generally used, such as sandblasting, which can remove rust, roughen the surface, and improve the adhesion of the coating. It is suitable for the surface treatment of alloy die-castings for camera housings.

[0004] However, in the process of organic coating film formation, it will undergo physical and chemical changes such as high-temperature melting, cross-linking, condensation or rapid volatilization of solvents. As the coating thickness increases, the shrinkage stress generated in the later stage of film formation will also increase. When this stress exceeds the surface tension of the metal, it is more likely to cause coating shrinkage, blistering and other problems, especially in the micropores or cracks on the surface of the substrate. The traditional degreasing, pickling and phosphating processes after sandblasting can remove surface oil and oxide film, but cannot completely solve the problems of surface defects and changes in surface tension. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a sandblasting coating for a camera housing and a preparation process thereof.

[0006] A process for preparing a sandblasting coating for a camera housing comprises the following steps:

[0007] (1) Pretreatment: Use pure water or mild detergent to clean the camera housing die-casting, remove surface oil and dust, and dry it naturally or with compressed air;

[0008] (2) Sand blasting: sand blasting the pre-treated camera housing die casting using abrasive to form a uniform rough surface;

[0009] (3) Phosphoric acid treatment: The camera housing die casting after sandblasting is immersed in phosphoric acid treatment solution for 30-40 seconds, taken out and left for 30 seconds, and then washed and dried;

[0010] (4) Spray coating: spray a layer of organic coating on the surface of the camera housing die casting treated with phosphoric acid to form a protective coating;

[0011] (5) Steam treatment: The camera housing die casting is treated at 80-90° C. for 10-15 minutes to form a sandblasting coating on the surface of the camera housing.

[0012] Among them, the abrasive used in the sandblasting treatment is aluminum oxide or glass beads; the concentration ratio of phosphoric acid to additives in the phosphoric acid treatment solution is 1-3:5, and the phosphoric acid concentration is 10ml / L; the organic coating is a UV curing coating or a powder coating, and the protective coating is completely hardened by UV irradiation or thermal curing.

[0013] Furthermore, in the sandblasting treatment, the sandblasting pressure is 0.3 to 0.6 MPa, the blasting distance is 80 to 150 mm, the blasting angle is 70° to 90°, and the target surface roughness Ra value is ≤10 μm.

[0014] Furthermore, the mass ratio of the emulsifier, the thickener and the corrosion inhibitor in the additive of the phosphoric acid treatment liquid is 5:2:1, the emulsifier is polyoxyethylene ether, the thickener is hydroxyethyl cellulose, and the corrosion inhibitor is benzotriazole.

[0015] Furthermore, the protective coating is sprayed using electrostatic spraying or high-pressure airless spraying technology, and the coating thickness is controlled to be 50 to 100 μm.

[0016] Furthermore, the water vapor treatment also includes a final curing treatment. For UV-curing coatings, the surface of the camera housing die-casting is cured by UV lamp irradiation; for powder coatings, the camera housing die-casting is moved to an oven for heating and curing at 120-150°C for 15 to 30 minutes.

[0017] Furthermore, the UV curing coating adopts UV curing polyurethane acrylate coating, and the specific components include by mass percentage: 60% polyurethane acrylate resin, 5% photoinitiator, 20% pigment, 10% filler, and 5% additive.

[0018] Furthermore, the powder coating adopts thermosetting polyester resin coating, and the specific components include by mass percentage: 50% polyester resin, 10% curing agent, 20% pigment, 15% filler, and 5% additive.

[0019] Furthermore, the powder coating adopts epoxy resin coating, and the specific components by mass percentage include: 40% bisphenol A epoxy resin, 5% siloxane compound, 10% polyurethane dispersion, 8% curing agent, 20% pigment, 7% filler, and 4% additive.

[0020] Furthermore, the camera housing die-casting is made of aluminum alloy and zinc alloy that are heated and melted into liquid metal, and then the liquid metal is made into a die-casting part using a die-casting mold, and the die-casting part is machined through turning, milling, drilling, and CNC processes.

[0021] A sandblasting coating for a camera housing is prepared by the preparation process of the sandblasting coating for a camera housing.

[0022] The beneficial effects achieved by the present invention are as follows: 1. The present invention combines sandblasting and phosphoric acid treatment to improve the adhesion between the organic coating and the aluminum alloy substrate, ensuring that the coating is not easy to peel off or bubble. The tiny pits and protrusions formed by sandblasting increase the surface roughness, provide more "anchor points" for subsequent coatings, and enhance the mechanical bite force. The aluminum phosphate conversion film generated by phosphoric acid treatment fills the surface micropores and cracks, and changes the surface chemical properties to form a large number of hydroxyl groups and other active sites. These sites can react with the functional groups in the organic coating to form covalent bonds or hydrogen bonds, further enhancing the adhesion, thereby solving the problems of surface defects and changing surface tension.

[0023] 2. After the phosphoric acid treatment, the conversion film formed in the present invention acts as an inorganic barrier, which can effectively block the intrusion of moisture, oxygen and other corrosive media, improve the corrosion resistance of the coating, and the formation of the conversion film can stabilize the interface between the substrate and the coating, reducing the stress concentration and peeling risk caused by environmental changes.

[0024] 3. The present invention provides suitable humidity and temperature conditions through water vapor treatment, promotes the further formation of aluminum phosphate conversion film, enhances its integrity and stability, accelerates the initial curing of the paint coating, reduces the energy consumption and time of subsequent high-temperature curing, and the lower surface tension helps the paint to spread more evenly on the substrate, reduces defects such as shrinkage cavities and blistering, and improves the appearance quality and durability of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a schematic flow chart of a process for preparing a sandblasting coating for a camera housing. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments.

[0027] It should be understood that the following examples are only for illustrative purposes and explanation of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope of protection intended by the present invention.

[0028] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art.

[0029] Embodiment 1: A process for preparing a sandblasting coating for a camera housing, such as Figure 1 As shown, the following steps are included:

[0030] (1) Pretreatment: Use a mild detergent to clean the aluminum alloy camera housing die-casting, remove surface oil and dust, and blow dry with compressed air;

[0031] (2) Sand blasting: The pre-treated camera housing die casting was sand blasted using aluminum oxide abrasive. The sand blasting pressure was 0.4 MPa, the blasting distance was 100 mm, the blasting angle was 85°, and the target surface roughness Ra value was ≤8 μm.

[0032] (3) Phosphoric acid treatment: The camera housing die casting after sandblasting was immersed in a phosphoric acid treatment solution for 35 seconds. The concentration ratio of phosphoric acid to additives in the phosphoric acid treatment solution was 1:5, the phosphoric acid concentration was 10 ml / L, and the mass ratio of polyoxyethylene ether emulsifier, hydroxyethyl cellulose thickener and benzotriazole corrosion inhibitor in the additive was 5:2:1. After treatment, the die casting was taken out and left for 30 seconds, and then washed with water and dried.

[0033] (4) Spray coating: spray a layer of UV curing polyurethane acrylate coating on the surface of the camera housing die casting treated with phosphoric acid, wherein the coating comprises 60% polyurethane acrylate resin, 5% photoinitiator, 20% pigment, 10% filler, and 5% additive by weight, and electrostatic spraying is used to form a protective coating with a thickness of 70 μm;

[0034] (5) Steam treatment: The camera housing die casting is treated at 85°C for 12 minutes and finally cured using a UV lamp to form a sandblasting coating.

[0035] Embodiment 2: A process for preparing a sandblasting coating for a camera housing, such as Figure 1 As shown, the following steps are included:

[0036] (1) Pretreatment: Use pure water to clean the aluminum alloy camera housing die-casting, remove surface oil and dust, and blow dry with compressed air;

[0037] (2) Sand blasting: Use glass bead abrasive to sand blast the pre-treated camera housing die casting. The sand blasting pressure is 0.5 MPa, the blasting distance is 120 mm, the blasting angle is 90°, and the target surface roughness Ra value is ≤10 μm.

[0038] (3) Phosphoric acid treatment: The camera housing die casting after sandblasting was immersed in a phosphoric acid treatment solution for 40 seconds. The concentration ratio of phosphoric acid to additives in the phosphoric acid treatment solution was 2:5, the phosphoric acid concentration was 10 ml / L, and the mass ratio of polyoxyethylene ether emulsifier, hydroxyethyl cellulose thickener and benzotriazole corrosion inhibitor in the additive was 5:2:1. After treatment, the die casting was taken out and left for 30 seconds, and then washed with water and dried.

[0039] (4) Spray coating: spray a layer of thermosetting polyester resin powder coating on the surface of the camera housing die-casting treated with phosphoric acid, wherein the coating composition comprises 50% polyester resin, 10% curing agent, 20% pigment, 15% filler, and 5% additive by weight, and high-pressure airless spraying is used to form a protective coating with a thickness of 80 μm;

[0040] (5) Steam treatment: The camera housing die casting is treated at 80°C for 15 minutes, and finally the camera housing die casting is moved to an oven for heating and curing, and cured at 130°C for 20 minutes to form a sandblasting coating.

[0041] Embodiment 3: A process for preparing a sandblasting coating for a camera housing, such as Figure 1 As shown, the following steps are included:

[0042] (1) Pretreatment: Use a mild detergent to clean the aluminum alloy camera housing die-casting, remove surface oil and dust, and dry it naturally;

[0043] (2) Sand blasting: The pre-treated camera housing die casting was sand blasted using aluminum oxide abrasive. The sand blasting pressure was 0.3 MPa, the blasting distance was 80 mm, the blasting angle was 70°, and the target surface roughness Ra value was ≤6 μm.

[0044] (3) Phosphoric acid treatment: The camera housing die casting after sandblasting was immersed in a phosphoric acid treatment solution for 30 seconds. The concentration ratio of phosphoric acid to additive in the phosphoric acid treatment solution was 1:5, the phosphoric acid concentration was 10 ml / L, and the mass ratio of polyoxyethylene ether emulsifier, hydroxyethyl cellulose thickener and benzotriazole corrosion inhibitor in the additive was 5:2:1. After treatment, the die casting was taken out and left for 30 seconds, and then washed with water and dried.

[0045] (4) Spray coating: spray a layer of UV curing polyurethane acrylate coating on the surface of the camera housing die casting treated with phosphoric acid, wherein the coating comprises 60% polyurethane acrylate resin, 5% photoinitiator, 20% pigment, 10% filler, and 5% additive by weight, and electrostatic spraying is used to form a protective coating with a thickness of 50 μm;

[0046] (5) Steam treatment: The camera housing die casting is treated at 90°C for 10 minutes and finally cured using a UV lamp to form a sandblasting coating.

[0047] Comparative Example 1: Compared with Example 1, this comparative example does not undergo phosphoric acid treatment and water vapor treatment.

[0048] Comparative Example 2: Compared with Example 1, this comparative example does not undergo steam treatment.

[0049] Performance test: Adhesion, corrosion resistance and impact resistance of the sandblasting coating of the camera housing of Examples 1-3 and Comparative Examples 1-2 were tested;

[0050] 1. Adhesion test: According to GB / T 9286-1998 "Cross-cut test for paint and varnish film", use a cross-cutting tool to cut a square grid with a spacing of 1 mm on the surface of the sample. The cutting depth should penetrate the substrate. Stick a transparent pressure-sensitive tape (3M No. 600) that meets the standard on the grid and press lightly with your fingers to ensure full contact. Quickly tear off the tape in the vertical direction at a tearing speed of about 30 cm per second. Rating according to the standard based on the state of the residual paint film.

[0051] 2. Corrosion resistance test: According to GB / T 10125-2012 "Artificial atmosphere corrosion test salt spray test", fix the sample in the salt spray test chamber, the sample is at an angle of 15°-30° to the vertical plane, use chemically pure sodium chloride to prepare a 5±1% salt solution, adjust the pH value to between 6.5-7.2, start the salt spray test chamber, maintain the temperature in the test chamber at 35±2℃, continue spraying for 168 hours, observe and record, after the test, take out the sample, clean and dry it, and evaluate the corrosion resistance of the coating.

[0052] 3. Impact resistance test: According to GB / T 1732-1993 "Determination of impact resistance of paint film", fix the sample on the workbench of the impact tester, adjust the height of the impact head, let it fall freely from the specified height and hit the surface of the sample, use a heavy hammer (1 kg) to fall freely from different heights and hit the surface of the sample, check whether the coating has cracks, peeling or other damage, and record the maximum impact energy.

[0053] The performance test results are shown in the table below.

[0054] Table 1 Test results of various properties of sandblasting coating for camera housing

[0055]

[0056]

[0057] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A process for preparing a sandblasting coating for a camera housing, characterized in that: The following steps are involved: (1) Pretreatment: Use pure water or mild detergent to clean the camera housing die-casting, remove surface oil and dust, and dry it naturally or with compressed air; (2) Sand blasting: sand blasting the pre-treated camera housing die casting using abrasive to form a uniform rough surface; (3) Phosphoric acid treatment: The camera housing die casting after sandblasting is immersed in phosphoric acid treatment solution for 30-40 seconds, taken out and left for 30 seconds, and then washed and dried; (4) Spray coating: spray a layer of organic coating on the surface of the camera housing die casting treated with phosphoric acid to form a protective coating; (5) Steam treatment: The camera housing die casting is treated at 80-90° C. for 10-15 minutes to form a sandblasting coating on the surface of the camera housing; Among them, the abrasive used in the sandblasting treatment is aluminum oxide or glass beads; the concentration ratio of phosphoric acid to additives in the phosphoric acid treatment solution is 1-3:5, and the phosphoric acid concentration is 10ml / L; the organic coating is a UV curing coating or a powder coating, and the protective coating is completely hardened by UV irradiation or thermal curing.

2. The process for preparing a sandblasting coating for a camera housing according to claim 1, characterized in that: In the sandblasting treatment, the sandblasting pressure is 0.3 to 0.6 MPa, the blasting distance is 80 to 150 mm, the blasting angle is 70° to 90°, and the target surface roughness Ra value is ≤10 μm.

3. The process for preparing a sandblasting coating for a camera housing according to claim 1, characterized in that: The mass ratio of the emulsifier, the thickener and the corrosion inhibitor in the additive of the phosphoric acid treatment liquid is 5:2:1, the emulsifier is polyoxyethylene ether, the thickener is hydroxyethyl cellulose, and the corrosion inhibitor is benzotriazole.

4. The process for preparing a sandblasting coating for a camera housing according to claim 1, characterized in that: The protective coating is sprayed by electrostatic spraying or high-pressure airless spraying technology, and the coating thickness is controlled to be 50 to 100 μm.

5. The process for preparing a sandblasting coating for a camera housing according to claim 1, characterized in that: The steam treatment also includes a final curing treatment. For UV curing coatings, the surface of the camera housing die casting is cured by UV lamp irradiation; for powder coatings, the camera housing die casting is moved to an oven for heating and curing at 120-150°C for 15 to 30 minutes.

6. The process for preparing a sandblasting coating for a camera housing according to claim 1, characterized in that: The UV curing coating adopts UV curing polyurethane acrylate coating, and the specific components include 60% polyurethane acrylate resin, 5% photoinitiator, 20% pigment, 10% filler and 5% auxiliary agent by mass percentage.

7. The process for preparing a sandblasting coating for a camera housing according to claim 1, characterized in that: The powder coating adopts thermosetting polyester resin coating, and the specific components include: 50% polyester resin, 10% curing agent, 20% pigment, 15% filler and 5% auxiliary agent by mass percentage.

8. The process for preparing a sandblasting coating for a camera housing according to claim 1, characterized in that: The powder coating adopts epoxy resin coating, and the specific components include by mass percentage: 40% bisphenol A epoxy resin, 5% siloxane compound, 10% polyurethane dispersion, 8% curing agent, 20% pigment, 7% filler and 4% auxiliary agent.

9. The process for preparing a sandblasting coating for a camera housing according to claim 1, characterized in that: The camera housing die-casting is made of aluminum alloy and zinc alloy that are heated and melted into liquid metal, and then the liquid metal is made into a die-casting part using a die-casting mold, and the die-casting part is machined through turning, milling, drilling, and CNC processes.

10. A sandblasting coating for a camera housing, characterized in that: Prepared according to the preparation process according to any one of claims 1 to 9.

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