Metal surface oil and film removing process

Abstract

The invention discloses a metal surface oil and film removing process. The metal surface oil and film removing process comprises the following steps that S1, spraying oil removing treatment is conducted on a metal base material; s2, the oil-removed metal base material is directly subjected to spraying film forming treatment; in the step S1, an oil removing agent is adopted for spraying, and in the step S2, organic silicon resin is adopted for spraying; the degreasing agent in the step S1 comprises a water-soluble organic solvent compounded surfactant, and the water-soluble organic solvent is one or more of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, ethanol and dipropylene glycol monomethyl ether. In the step S1, a water-soluble organic solvent is compounded with a surfactant to carry out oil removal treatment on a metal base material, most of oil stains on the metal surface can be efficiently removed, in the step S2, organic silicon resin is adopted to carry out spraying film forming, an oil film layer can permeate to form a film on the metal surface, and therefore after spraying oil removal, water washing is not needed, and the oil stain removal efficiency is improved. The film forming procedure can be directly carried out, so that the time of the whole procedure is greatly shortened, and the processing efficiency is improved.

Description

Technical Field

[0001] This invention relates to a metal surface treatment process, and more particularly to a metal surface degreasing and coating process. Background Technology

[0002] Currently, three main processes are still in use in the pretreatment of metal substrates for white goods: phosphating, ceramic coating, and silane coating. Under increasingly stringent environmental requirements, all three processes have environmentally unfriendly aspects. Specifically, phosphating produces products containing large amounts of acid and heavy metal ions; the production process also releases large amounts of volatile nitrogen oxides and phosphating slag, which is very harmful to the environment and human health. Ceramic coating still contains a certain amount of acid and metal ions. Silane coating has relatively weak overall performance, poor resistance to neutral salt spray, and watermarks at water accumulation points.

[0003] Meanwhile, all three processes mentioned above require degreasing, washing, and coating steps, meaning that washing is necessary during these steps. A significant amount of time is spent on washing during production. For example, application number 201611183180.7 discloses an environmentally friendly novel ceramic coating agent and its preparation method, which involves degreasing the metal surface, washing it, applying the ceramic coating, and then washing it again, thus increasing the production cycle. Furthermore, the continuous and overflowing water during washing in these three processes leads to constant wastewater discharge during production, resulting in high production costs and significant pressure on enterprises. Summary of the Invention

[0004] The purpose of this invention is to provide a metal surface degreasing and coating process that can solve at least one of the above problems.

[0005] According to one aspect of the present invention, a metal surface degreasing and coating process is provided, comprising the following steps: S1. Spray degreasing treatment on metal substrates; S2. The degreased metal substrate is directly subjected to spray film formation treatment. In step S1, an oil remover is used for spraying, and in step S2, an organosilicon resin is used for spraying.

[0006] In some embodiments, the degreasing agent in step S1 includes a water-soluble organic solvent compounded with a surfactant, wherein the water-soluble organic solvent is one or more of ethylene glycol monobutyl ether, diethylene glycol butyl ether, ethanol, and dipropylene glycol methyl ether.

[0007] In some embodiments, the surfactant is a fatty alcohol polyoxyethylene ether.

[0008] In some implementations, the spraying degreasing time in step S1 is greater than 5 minutes, and the spraying film-forming time in step S2 is greater than 30 seconds.

[0009] In some embodiments, the spraying pressure in steps S1 and S2 is 0.1~0.15MPa, and the spraying temperature is greater than or equal to 20°C.

[0010] In some embodiments, step S1 is performed in an oil removal tank and step S2 is performed in a film forming tank, both of which are connected to an external circulating decontamination device.

[0011] In some implementations, there are multiple degreasing tanks in step S1.

[0012] The beneficial effects of this invention are: 1. In step S1, water-soluble organic solvents are used to degrease the metal substrate with a surfactant. This can efficiently remove most of the oil stains from the metal surface, so that the minimal residue will not negatively affect the performance of the film formed later. Therefore, after spraying to remove oil, there is no need to wash with water, and the film can be directly entered into the film forming process, which greatly shortens the time of the entire process and improves the processing efficiency. 2. In step S2, silicone resin is used for spraying to form a film. Since silicone resin has oleophilic functional groups, it has a strong ability to penetrate and penetrate the oil film. It can help the resin pass through the residual oil film layer and directly contact the metal substrate itself. It forms a certain number and density of related hydrogen bonds with the hydroxyl groups contained in the metal substrate. This allows the hydroxyl groups to dehydrate and form bonds during the subsequent high-temperature baking stage, ultimately forming a resin film layer, which provides a strong adhesive layer for the subsequent outer coating. 3. By controlling the spraying time in S1, the oil removal effect can be guaranteed; by controlling the spraying time and temperature, the oil removal efficiency can be guaranteed; by controlling the spraying pressure, the oil removal efficiency can be guaranteed. 4. Both the degreasing tank and the film-forming tank are connected to an external circulating decontamination device, which can treat oil stains and other contaminants, greatly reducing pollution to the external environment and achieving environmental protection. Detailed Implementation

[0014] The present invention will now be described in further detail.

[0015] The metal surface degreasing and coating process of the present invention includes the following steps: S1. Spray degreasing treatment on metal substrates; S2. The degreased metal substrate is directly subjected to spray film formation treatment. In step S1, an oil remover is used for spraying, and in step S2, an organosilicon resin is used for spraying.

[0016] Because silicone resin is used in step S2, its lipophilic functional groups can penetrate the oil film and act on the metal substrate during spraying. The lipophilic functional groups are mainly alkane groups, including methyl and butyl, which have excellent penetration ability through the oil film. Therefore, when the silicone resin is sprayed, it can penetrate the residual oil film layer, allowing its high-density silanol groups to directly contact the metal substrate itself and form a certain number and density of associated hydrogen bonds with the hydroxyl groups contained in the substrate. Therefore, after the metal substrate film is formed, during the subsequent high-temperature baking stage, the hydroxyl groups undergo a dehydration reaction to form bonds, ultimately forming a resin film layer, providing a strong adhesive layer for the subsequent adhesion of the outer coating.

[0017] This process can be easily operated by spraying during both degreasing and film formation.

[0018] The degreasing agent in step S1 includes a water-soluble organic solvent compounded with a surfactant. The water-soluble organic solvent is one or more of ethylene glycol monobutyl ether, diethylene glycol butyl ether, ethanol, and dipropylene glycol methyl ether.

[0019] The surfactant is a fatty alcohol polyoxyethylene ether. Therefore, by adding this surfactant to the degreasing agent, the entire degreasing agent has excellent oil emulsification and stripping properties, which can efficiently remove most of the oil stains on the surface of the workpiece, and its residue will not have a significant negative impact on the performance and appearance of the subsequently formed film.

[0020] In step S1, the spraying degreasing time is greater than 5 minutes, and in step S2, the spraying film-forming time is greater than 30 seconds. The spraying pressure in both steps S1 and S2 is 0.1~0.15 MPa, and the spraying temperature is greater than or equal to 20℃. Therefore, after step S1, sufficient degreasing time is ensured to effectively remove oil stains from the surface of the metal substrate without affecting the subsequent film-forming quality. Simultaneously, the temperature of 20℃ or higher during degreasing ensures the stability of the degreasing agent's performance and guarantees degreasing efficiency. Since the spraying time is no less than 30 seconds during film formation, it facilitates the formation of a resin film layer on the substrate surface by the silicone resin.

[0021] Therefore, the entire process can be carried out at room temperature without heating, which greatly reduces energy consumption and achieves energy-saving effect. During operation, the film is formed directly after degreasing without the need for water washing, which simplifies the process, greatly improves production efficiency, eliminates the wastewater discharge generated during the production cycle, reduces pollutant discharge, and lowers the company's production costs.

[0022] Step S1 is performed in the degreasing tank, and step S2 is performed in the film-forming tank. Both the degreasing tank and the film-forming tank are connected to an external circulating decontamination device. In actual use, the degreasing tank is connected to one external circulating decontamination device, and the film-forming tank is connected to one external circulating decontamination device. To ensure degreasing quality, two or three degreasing tanks are used to facilitate effective degreasing of the metal substrate surface. During use, a small amount of bactericide can be added to each tank, and ultraviolet sterilization can be used to inhibit the growth of microorganisms in the tank and ensure the stability and odorlessness of the tank solution during the cycle.

[0023] During the spraying process, the degreasing agent is returned to the degreasing tank, and the silicone resin is returned to the film-forming tank. To ensure the degreasing performance of the degreasing agent, the pH value of the solution in the degreasing tank is maintained between 8.5 and 10; to ensure the film-forming effect, the pH value of the solution in the film-forming tank is maintained between 7.5 and 9.5, thus ensuring the corresponding performance of each spraying solution.

[0024] The external circulating decontamination equipment mainly employs ultrasonic demulsification and ultrafiltration technologies. Both ultrasonic demulsification and ultrafiltration are existing technologies, and their specific working principles will not be elaborated here. Ultrasonic demulsification separates the emulsified surfactants and oils in the tank solution, forming floating oil sludge, which is then removed by skimming. Next, ultrafiltration separates particulate impurities, ensuring that the contaminants in the tank solution are kept at a suitable low level. This allows the tank solution to be recycled, ensuring that each tank's lifespan is maintained within a relatively long and acceptable period.

[0025] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A metal surface degreasing and coating process, characterized in that, Includes the following steps: S1. Spray degreasing treatment on metal substrates; S2. The degreased metal substrate is directly subjected to spray film formation treatment. In step S1, an oil remover is used for spraying, and in step S2, an organosilicon resin is used for spraying.

2. The metal surface degreasing and film formation process according to claim 1, characterized in that, The degreasing agent in step S1 includes a water-soluble organic solvent compounded with a surfactant, wherein the water-soluble organic solvent is one or more of ethylene glycol monobutyl ether, diethylene glycol butyl ether, ethanol, and dipropylene glycol methyl ether.

3. The metal surface degreasing and film formation process according to claim 1, characterized in that, The degreasing agent in step S1 includes a water-soluble organic solvent compounded with a surfactant, wherein the water-soluble organic solvent is one or more of ethylene glycol monobutyl ether, diethylene glycol butyl ether, ethanol, and dipropylene glycol methyl ether.

4. The metal surface degreasing and film formation process according to any one of claims 1 to 3, characterized in that, In step S1, the spraying time for oil removal is greater than 5 minutes, and in step S2, the spraying time for film formation is greater than 30 seconds.

5. The metal surface degreasing and film formation process according to claim 4, characterized in that, The spraying pressure in steps S1 and S2 is 0.1~0.15MPa, and the spraying temperature is greater than or equal to 20℃.

6. The metal surface degreasing and film formation process according to claim 5, characterized in that, Step S1 is performed in the degreasing tank, and step S2 is performed in the film-forming tank. Both the degreasing tank and the film-forming tank are connected to an external circulating decontamination device.

7. The metal surface degreasing and film formation process according to claim 6, characterized in that, In step S1, there are multiple degreasing tanks.