Application of a silicone resin in surface treatment of metal workpieces

Abstract

The present invention relates to the technical field of C23C22 / 00, and specifically to an application of an organosilicon resin in the surface treatment of a metal workpiece. An application of an organosilicon resin in the surface treatment of a metal workpiece comprises the following steps: S1. adding an organosilicon resin to water for mixing and stirring to obtain a mixture a; S2. adding an epoxy-modified organosilicon resin to the mixture a for stirring to obtain a treatment agent a; S3. adding the treatment agent a to water to prepare a treatment liquid; S4. immersing the metal workpiece in the treatment liquid for surface treatment; S5. spraying powder coating onto the surface of the metal workpiece. By using the organosilicon resin provided by the present invention in the surface treatment of a metal workpiece, the bonding performance between the surface of the metal workpiece and the powder coating is improved, and the metal workpiece has strong leveling properties, and there is no problem of leaving marks or white circles.

Description

Technical Field

[0001] The invention relates to the technical field of C23C22 / 00, and in particular to application of an organic silicon resin in surface treatment of a metal workpiece. Background Art

[0002] The Chinese patent application number CN201510769552.3 discloses a metal surface treatment agent with a silane coupling agent as the main component and a preparation method thereof. An amino-containing silane coupling agent and an epoxy-containing silane coupling agent are used to solve the problem that the treatment agent does not produce wastewater and waste residue containing heavy metals, and an organic-inorganic coating is formed on the surface of the metal material. However, the problem of improving the marks and white circles on the surface of the metal workpiece is not mentioned and solved. Therefore, providing a method that can improve the bonding performance between the surface of the metal workpiece and the powder coating, and has strong leveling properties, and does not leave marks or white circles is the main technical problem that needs to be solved at present. Summary of the invention

[0003] In order to solve the above problems, the present invention provides an application of an organosilicon resin in the surface treatment of a metal workpiece, comprising the following steps:

[0004] S1. Adding a silicone resin to water and mixing and stirring to obtain a mixture a;

[0005] S2. The epoxy-modified silicone resin is added to the mixture a and stirred to obtain a treating agent a;

[0006] S3. Add the treatment agent a to the water to prepare the treatment solution;

[0007] S4. Immersing the metal workpiece into the treatment liquid for surface treatment;

[0008] S5. Spray powder coating onto the surface of the metal workpiece.

[0009] Preferably, the number average molecular weight of the silicone resin is 1000-20000.

[0010] Preferably, the number average molecular weight of the silicone resin is 3000-15000.

[0011] Preferably, the silicone resin is a water-based silicone resin.

[0012] Preferably, the weight ratio of the silicone resin to water in S1 is 1:(15-25).

[0013] In order to improve the white ring produced by the treatment liquid on the surface of the metal workpiece and improve the bonding performance of the powder coating and the metal workpiece, the applicant found in the experiment that adding silicone resin to the treatment liquid instead of the single molecule silane in the prior art can solve the problem of white rings on the surface of the metal workpiece when the number average molecular weight of the silicone resin is 1000-20000, especially when the number average molecular weight of the silicone resin is 3000-15000, and can further improve the bonding performance of the powder coating and the metal workpiece. The possible reason is that the number average molecular weight of the single molecule silane is small, and when the metal oxide layer interacts with the metal workpiece surface, it is equivalent to forming a small amount of claw-type connection, but the number of its action points is small and its adhesion is poor. When the metal workpiece is taken out of the treatment liquid, single-molecule silane is likely to remain at the bottom of the metal workpiece, and white circles will appear after drying. After spraying powder coating, the powder coating cannot be evenly sprayed on the surface of the metal workpiece. However, after adding silicone resin, the silicone resin has a large number average molecular weight and has more silanol groups. When interacting with the metal oxide layer on the surface of the metal workpiece, it is equivalent to forming a large number of claw-type connections. The number of action points is large and it is easy to adhere to the surface of the metal workpiece. When the metal workpiece is taken out of the treatment liquid, it is not easy to remain at the bottom of the metal workpiece, and there will be no white circle problem when drying. In addition, when the powder coating is sprayed on the surface of the metal workpiece, it can adhere to the surface of the metal workpiece evenly.

[0014] Preferably, the number average molecular weight of the epoxy-modified silicone resin is 1,000-10,000.

[0015] Preferably, the number average molecular weight of the epoxy-modified silicone resin is 3000-9000.

[0016] Preferably, the concentration of the treating agent a in the treating solution is 2-5%.

[0017] Preferably, the weight ratio of the epoxy-modified silicone resin to the silicone resin is 1:(1.5-3).

[0018] In order to improve the bare mold rust prevention ability of metal workpieces, the applicant unexpectedly discovered in experiments that when epoxy-modified silicone resin and silicone resin are used in combination, and the weight ratio of epoxy-modified silicone resin to silicone resin is 1: (1.5-3), the number average molecular weight of silicone resin is 1000-20000, and the number average molecular weight of epoxy-modified silicone resin is 1000-10000, the bare film rust prevention ability of metal workpieces can be enhanced. The possible reason is that the modified silicone resin and silicone resin can better act on the surface of the metal workpiece, and can form a layer of effective film on the surface of the workpiece to block the water vapor or oxygen in the environment from oxidizing and corroding the metal surface, and when the powder coating is sprayed on the surface of the metal workpiece, it can evenly adhere to the surface of the metal workpiece to form a strong bonding force.

[0019] Preferably, the electrical conductivity of the water is less than 400 us / cm.

[0020] Preferably, the pH value of the treatment liquid is 7-9.

[0021] Preferably, in S4, the metal workpiece is placed vertically after surface treatment and then dried.

[0022] Preferably, the metal workpiece is made of an alloy material such as iron, aluminum, or zinc.

[0023] Preferably, the powder coating spraying thickness in S5 is 10-80 um.

[0024] Beneficial Effects

[0025] 1. In the present application, the surface of the metal workpiece is treated with an organic silicone resin, thereby improving the bonding performance between the sprayed powder coating and the metal workpiece.

[0026] 2. The application of the organic silicone resin provided by the present invention in the surface treatment of metal workpieces improves the bonding performance between the surface of the metal workpiece and the powder coating, and has strong leveling properties without the problems of leaving marks or white circles.

[0027] 3. In the present application, the epoxy-modified silicone resin and the silicone resin are used together to enhance the bare mold rust resistance of the metal workpiece.

[0028] 4. In this application, no amine rust inhibitor or resin is added, the COD value is low, and the problem of bacteria growth and odor in the treatment liquid in a static state is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a state diagram of the metal workpiece surface in Example 1.

[0030] Figure 2 This is a state diagram of the metal workpiece surface in Example 4. DETAILED DESCRIPTION

[0031] Example 1

[0032] An application of an organosilicon resin in the surface treatment of a metal workpiece comprises the following steps:

[0033] S1. Adding a silicone resin to water and mixing and stirring to obtain a mixture a;

[0034] S2. The epoxy-modified silicone resin is added to the mixture a and stirred to obtain a treating agent a;

[0035] S3. Add the treatment agent a to the water to prepare the treatment solution;

[0036] S4. Immersing the metal workpiece into the treatment liquid for surface treatment;

[0037] S5. Spray powder coating onto the surface of the metal workpiece.

[0038] The number average molecular weight of the silicone resin is 7000.

[0039] The organic silicone resin is a water-based organic silicone resin.

[0040] The water-based silicone resin was purchased from Shanghai Wenjing Chemical Technology Co., Ltd.

[0041] The organic silicone resin is a water-based organic silicone resin.

[0042] The number average molecular weight of the epoxy-modified silicone resin is 6500.

[0043] The epoxy-modified silicone resin was purchased from Shanghai Wenjing Chemical Technology Co., Ltd.

[0044] The concentration of the treatment agent a in the treatment solution is 2.5%.

[0045] The weight ratio of the epoxy-modified silicone resin to the silicone resin is 1:2.5.

[0046] The weight ratio of the silicone resin to water in S1 is 1:20.

[0047] The electrical conductivity of the water is 40 us / cm.

[0048] The pH value of the treatment solution was adjusted to 8.5.

[0049] In S4, the metal workpiece is placed vertically after surface treatment and then dried.

[0050] The material of the metal workpiece is aluminum alloy.

[0051] The powder coating spraying thickness in S5 is 50 um.

[0052] Example 2

[0053] An application of an organosilicon resin in the surface treatment of a metal workpiece comprises the following steps:

[0054] S1. Adding a silicone resin to water and mixing and stirring to obtain a mixture a;

[0055] S2. The epoxy-modified silicone resin is added to the mixture a and stirred to obtain a treating agent a;

[0056] S3. Add the treatment agent a to the water to prepare the treatment solution;

[0057] S4. Immersing the metal workpiece into the treatment liquid for surface treatment;

[0058] S5. Spray powder coating onto the surface of the metal workpiece.

[0059] The number average molecular weight of the organic silicone resin is 5000.

[0060] The organic silicone resin is a water-based organic silicone resin.

[0061] The water-based silicone resin was purchased from Shanghai Wenjing Chemical Technology Co., Ltd.

[0062] The organic silicone resin is a water-based organic silicone resin.

[0063] The number average molecular weight of the epoxy-modified silicone resin is 4,000.

[0064] The epoxy-modified silicone resin was purchased from Shanghai Wenjing Chemical Technology Co., Ltd.

[0065] The concentration of the treatment agent a in the treatment solution is 2.5%.

[0066] The weight ratio of the epoxy-modified silicone resin to the silicone resin is 1:2.

[0067] The weight ratio of the silicone resin to water in S1 is 1:20.

[0068] The electrical conductivity of the water is 40 us / cm.

[0069] The pH value of the treatment solution was adjusted to 8.5.

[0070] In S4, the metal workpiece is placed vertically after surface treatment and then dried.

[0071] The material of the metal workpiece is aluminum alloy.

[0072] The powder coating spraying thickness in S5 is 50 um.

[0073] Example 3

[0074] An application of an organosilicon resin in the surface treatment of a metal workpiece comprises the following steps:

[0075] S1. Adding a silicone resin to water and mixing and stirring to obtain a mixture a;

[0076] S2. The epoxy-modified silicone resin is added to the mixture a and stirred to obtain a treating agent a;

[0077] S3. Add the treatment agent a to the water to prepare the treatment solution;

[0078] S4. Immersing the metal workpiece into the treatment liquid for surface treatment;

[0079] S5. Spray powder coating onto the surface of the metal workpiece.

[0080] The number average molecular weight of the organic silicone resin is 9,000.

[0081] The organic silicone resin is a water-based organic silicone resin.

[0082] The water-based silicone resin was purchased from Shanghai Wenjing Chemical Technology Co., Ltd.

[0083] The organic silicone resin is a water-based organic silicone resin.

[0084] The number average molecular weight of the epoxy-modified silicone resin is 9,000.

[0085] The epoxy-modified silicone resin was purchased from Shanghai Wenjing Chemical Technology Co., Ltd.

[0086] The concentration of the treatment agent a in the treatment solution is 2.5%.

[0087] The weight ratio of the epoxy-modified silicone resin to the silicone resin is 1:3.

[0088] The weight ratio of the silicone resin to water in S1 is 1:20.

[0089] The electrical conductivity of the water is 40 us / cm.

[0090] The pH value of the treatment solution was adjusted to 8.5.

[0091] In S4, the metal workpiece is placed vertically after surface treatment and then dried.

[0092] The material of the metal workpiece is aluminum alloy.

[0093] The powder coating spraying thickness in S5 is 50 um.

[0094] Example 4

[0095] The difference between Example 4 and Example 1 is that γ-aminopropyltriethoxysilane is used to replace the silicone resin in S1, and tri(2-hydroxyethyl)amine is used to replace the epoxy silicone resin in S2.

[0096] Performance Testing

[0097] 1. Appearance test:

[0098] 40 metal workpieces were processed according to the application steps provided in Examples 1-4, with 10 metal workpieces processed in each example. After the metal workpieces were surface treated, they were placed vertically and dried to see if there were any marks or white circles. The observation results were recorded. The results are shown in Table 1.

[0099] 2. Salt spray resistance test:

[0100] After the metal workpiece is treated and scratched according to the application steps provided in Examples 1-4, the metal workpiece is subjected to a salt spray test using the GB / T1771-91 salt spray resistance test method. The test time is 300 hours. After the test, the state of powder falling off at the scratches on the surface of the workpiece is observed. The state diagram of the metal workpiece surface in Example 1 is shown in FIG. Figure 1 , the state diagram of the metal workpiece surface in Example 4 is shown in Figure 2 .

[0101] Table 1

[0102] Example Apparent state Example 1 No marks, no white circles Example 2 No marks, no white circles Example 3 No marks, no white circles Example 4 There are marks and white circles

[0103] It can be seen from the data in Table 1 that in Example 4, γ-aminopropyl triethoxysilane is used in S1 to replace the silicone resin, and tris(2-hydroxyethyl)amine is used in S2 to replace the epoxy silicone resin. After the surface treatment of the metal workpiece, there will be marks and white circles, and through Figure 1 and Figure 2 It can be seen that after the metal workpiece in Example 4 is subjected to the salt spray resistance test, the width of the powder coating falling off the workpiece is greater than the falling area in Example 1, which also shows that the bonding force between the powder coating in Example 4 and the surface of the metal workpiece is worse than that in Example 1.

Claims

1. An application of an organosilicon resin in the surface treatment of a metal workpiece, characterized in that: The following steps are involved: S1. Adding a silicone resin to water and mixing and stirring to obtain a mixture a; S2. The epoxy-modified silicone resin is added to the mixture a and stirred to obtain a treating agent a; S3. Add the treatment agent a to the water to prepare the treatment solution; S4. Immersing the metal workpiece into the treatment liquid for surface treatment; S5. Spraying powder coating onto the surface of the metal workpiece; The number average molecular weight of the silicone resin is 1000-20000; The organic silicone resin is a water-based organic silicone resin; The number average molecular weight of the epoxy-modified silicone resin is 3000-9000; The weight ratio of the epoxy-modified silicone resin to the silicone resin is 1:(1.5-3); The concentration of the treating agent a in the treating solution is 2-5%.

2. The use of the organic silicone resin in the surface treatment of metal workpieces according to claim 1, characterized in that: The number average molecular weight of the silicone resin is 3000-15000.

3. The use of the organic silicone resin in the surface treatment of metal workpieces according to claim 1, characterized in that: The electrical conductivity of the water is less than 400 us / cm.

4. The use of the organic silicone resin in the surface treatment of metal workpieces according to claim 1, characterized in that: The pH value of the treatment liquid is 7-9.

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