Low-odor and high-corrosion-resistance hydrophilic finish paint for automobile coating as well as preparation method and application of low-odor and high-corrosion-resistance hydrophilic finish paint

Abstract

The invention discloses a low-odor and high-corrosion-resistance hydrophilic finish paint for automobile coating as well as a preparation method and application of the low-odor and high-corrosion-resistance hydrophilic finish paint. The hydrophilic finish paint is prepared from the following raw materials in parts by weight: 1 to 5 parts of film-forming resin, 1 to 5 parts of vanadyl sulfate, 0.1 to 1 part of ammonium zirconium carbonate, 0.1 to 1 part of an auxiliary agent and 88 to 97.8 parts of water. According to the hydrophilic finishing paint, by selecting the raw material components and utilizing the complexing ability of the novel resin to corrosion-resistant metal ions and the characteristic of low odor of the novel resin, the corrosion resistance of a coating is effectively improved, and the peculiar smell of the coating is reduced.

Description

Technical Field

[0001] The present invention relates to the field of topcoats for automobile air conditioners, and more specifically to a low-odor, highly corrosion-resistant hydrophilic topcoat for automobile painting, and a preparation method and application thereof. Background Art

[0002] As living standards improve, people's expectations for driving environments are becoming increasingly stringent. As a key component of automotive air conditioners, the performance of automotive evaporators is drawing increasing attention. In recent years, the issues of white powder spraying and odors in automotive air conditioners, which have been reported in the market, have gradually gained attention, and the relevant performance indicators have become increasingly stringent.

[0003] The problem of white powder spraying is primarily due to the evaporator's insufficient corrosion resistance, leading to electrochemical corrosion in the operating environment. This corrosion of the evaporator's aluminum substrate creates aluminum oxide / aluminum hydroxide powder that is blown out. The primary solution is to improve the evaporator's corrosion resistance, but currently available hydrophilic topcoats generally have weak corrosion resistance, requiring only environmentally polluting passivation treatments to achieve adequate corrosion resistance.

[0004] Regarding the odor problem, many odors are currently emitted by the evaporator's hydrophilic coating itself during the evaporation process. The main solution is to reduce the odor emitted by the coating itself along with the water. Currently, there is no complete solution to this problem in the industry. Summary of the Invention

[0005] Based on this, the present invention aims to provide a low-odor, highly corrosion-resistant hydrophilic topcoat for automotive coatings, as well as its preparation method and application. This hydrophilic topcoat, through the selection of raw material components, utilizes the novel resin's ability to complex corrosion-resistant metal ions and its inherent low-odor properties, effectively improving the coating's corrosion resistance and reducing its inherent odor.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In one aspect, the present invention provides a low-odor, highly corrosion-resistant hydrophilic topcoat for automotive coatings. The raw materials for forming the hydrophilic topcoat include the following components, in parts by weight: 1-5 parts of film-forming resin, 1-5 parts of vanadyl sulfate, 0.1-1 parts of ammonium zirconium carbonate, 0.1-1 parts of auxiliary agent and 88-97.8 parts of water.

[0007] Furthermore, the raw materials for forming the hydrophilic topcoat include the following components in parts by weight: 1-5 parts of film-forming resin, 1-3 parts of vanadyl sulfate, 0.1-0.5 parts of ammonium zirconium carbonate, 0.1-0.5 parts of auxiliary agent and 92-97.8 parts of water.

[0008] Furthermore, the film-forming resin is selected from ethylene-vinyl alcohol copolymer resin.

[0009] Furthermore, the auxiliary agent contains an antifungal and antibacterial agent.

[0010] Furthermore, the mildew and antibacterial agent is selected from one or more of isothiazolinone, carbendazim and nanosilver.

[0011] In another aspect, the present invention provides a method for preparing the hydrophilic topcoat as described in the first aspect, comprising the following steps: Add vanadyl sulfate to the water under stirring. After the vanadyl sulfate is completely dissolved and the solution is visually clear, continue stirring for 3-5 minutes. While stirring, continue to add the film-forming resin. After the film-forming resin is completely dissolved and the solution is visually uniform without precipitation, continue stirring for 3-5 minutes. While stirring, continue to add ammonium zirconium carbonate. After the ammonium zirconium carbonate is completely dissolved and the solution is visually uniform without precipitation, continue stirring for 3-5 minutes; While stirring, continue adding the additives. After all the additives are dissolved and the solution is visually uniform without precipitation, continue stirring for 3-5 minutes to obtain the hydrophilic topcoat.

[0012] Furthermore, the stirring rate is 300-400 rpm.

[0013] In yet another aspect, the present invention provides use of the hydrophilic topcoat as described in the first aspect in automobile painting.

[0014] Furthermore, in the application, the hydrophilic topcoat is used for coating automobile air conditioners.

[0015] Furthermore, the hydrophilic topcoat is applied on the surface of the automobile evaporator.

[0016] The beneficial effects of the present invention are as follows: The hydrophilic topcoat provided by the present invention is an aqueous emulsion of ethylene-vinyl alcohol copolymer containing vanadium and zirconium, which has little harm to the environment and reduces the environmental protection costs of enterprises. The hydrophilic topcoat has good storage stability and has greatly improved the corrosion resistance of automobile air-conditioning evaporators compared with corresponding products on the current market. The odor is significantly improved compared with current products in the industry. It has excellent corrosion resistance and odor resistance as a whole, and also has excellent drainage properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0018] Figure 1 Schematic diagram showing drainability test and evaporator volume.

[0019] Figure 2The figure shows the corrosion condition of the evaporator sprayed with the hydrophilic topcoat obtained in Example 1 after 480 hours of SST in a corrosion resistance experiment.

[0020] Figure 3 The figure shows the corrosion condition of the evaporator sprayed with the hydrophilic topcoat obtained in Comparative Example 1 after 480 hours of SST in a corrosion resistance experiment. DETAILED DESCRIPTION

[0021] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the following detailed description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0022] In response to current market concerns, one embodiment of the present invention provides a low-odor, highly corrosion-resistant hydrophilic topcoat for automotive coatings. This approach improves the white powder spray and odor issues often seen on automotive air conditioner evaporators, while maintaining the evaporator's excellent drainage properties. In this embodiment, the raw materials used to form the hydrophilic topcoat include the following components, measured in parts by weight: 1-5 parts of film-forming resin, 1-5 parts of vanadyl sulfate, 0.1-1 parts of ammonium zirconium carbonate, 0.1-1 parts of auxiliary agent and 88-97.8 parts of water.

[0023] In some preferred examples, the film-forming resin is selected from ethylene-vinyl alcohol copolymer resin.

[0024] In this embodiment, a hydrophilic topcoat formed by combining vanadyl sulfate, ammonium zirconium carbonate, and a film-forming resin in a specific ratio is applied to automotive air conditioner evaporators. The coated evaporators exhibit excellent corrosion resistance, significantly improved odor compared to existing products, and excellent water drainage. Specifically, the combination of vanadyl sulfate and ammonium zirconium carbonate significantly improves corrosion resistance compared to solutions using either vanadium or zirconium ions alone due to the complexation between vanadium and zirconium ions. However, this complexation prevents the two compounds from coexisting stably in the hydrophilic topcoat and easily forms a precipitate. In this embodiment, a specific film-forming resin is introduced to complex vanadium and zirconium ions so that they can be stably present in the product without precipitation. The product has good storage stability and is used in the coating film formation of automobile air-conditioning evaporators to ultimately form a highly corrosion-resistant coating. The resin commonly used in the current automotive hydrophilic topcoat market is usually polyvinyl alcohol, but acetic acid is used in its process. The coating formed on the evaporator has poor odor performance and is prone to produce a sour taste. The technical solution of this embodiment replaces the polyvinyl alcohol resin, thereby eliminating the source of the sour taste, and its performance in terms of the sour taste problem is significantly better than that of current products on the market.

[0025] In some specific examples, the raw materials for forming the hydrophilic topcoat include the following components in parts by weight: 1-5 parts of film-forming resin, 1-3 parts of vanadyl sulfate, 0.1-0.5 parts of ammonium zirconium carbonate, 0.1-0.5 parts of auxiliary agent and 92-97.8 parts of water.

[0026] Based on the above conditions, the obtained hydrophilic topcoat has good storage stability, and after being used for coating the automobile air-conditioning evaporator, the corrosion resistance, odor improvement and drainage effect are significantly improved.

[0027] In some preferred examples, the raw materials for forming the hydrophilic topcoat include the following components based on 100 parts by weight: 1-5 parts of film-forming resin, 1-2 parts of vanadyl sulfate, 0.1-0.2 parts of ammonium zirconium carbonate, 0.1-0.5 parts of auxiliary agent and the balance of water.

[0028] In some preferred examples, the auxiliary agent includes an antifungal and antibacterial agent. Suitable antifungal and antibacterial agents include, but are not limited to, one or more selected from the group consisting of isothiazolinone, carbendazim, and nanosilver.

[0029] In this embodiment, other additives may be added according to actual needs, which will not be described in detail here. It should be noted that, based on the above formula, the addition of other additives shall not affect the effect of the present invention.

[0030] In this embodiment, the solid content of the hydrophilic topcoat is preferably 2-6.5%.

[0031] In some preferred examples, the total weight of the raw materials forming the hydrophilic topcoat is 100 parts.

[0032] According to another embodiment of the present invention, a method for preparing the low-odor, highly corrosion-resistant hydrophilic topcoat for automotive coatings as described above is provided, the preparation method comprising the following steps: Add vanadyl sulfate to the water under stirring. After the vanadyl sulfate is completely dissolved and the solution is visually clear, continue stirring for 3-5 minutes. While stirring, continue to add the film-forming resin. After the film-forming resin is completely dissolved and the solution is visually uniform without precipitation, continue stirring for 3-5 minutes. While stirring, continue to add ammonium zirconium carbonate. After the ammonium zirconium carbonate is completely dissolved and the solution is visually uniform without precipitation, continue stirring for 3-5 minutes; While stirring, continue adding the additives. After all the additives are dissolved and the solution is visually uniform without precipitation, continue stirring for 3-5 minutes to obtain the hydrophilic topcoat.

[0033] In some specific examples, the stirring rate is 300-400 rpm.

[0034] By using the above preparation method and controlling the adding sequence and conditions, the hydrophilic topcoat with good workability can be prepared.

[0035] According to another specific embodiment of the present invention, there is provided a use of the low-odor and highly corrosion-resistant hydrophilic topcoat for automobile painting as described above in automobile painting.

[0036] In a specific example, in the application, the hydrophilic topcoat is used for coating automobile air conditioners.

[0037] In some more specific examples, the hydrophilic topcoat is applied to the surface of an automobile evaporator, which effectively solves the problems of white powder spraying and odor in existing automobile air conditioners, while also ensuring excellent drainage performance of the automobile air conditioner.

[0038] In some preferred examples, the application includes the following steps: The automobile evaporator is completely immersed in the hydrophilic topcoat, taken out, dried to form a film, and cooled to room temperature to form a coating film on the surface of the automobile evaporator.

[0039] Exemplarily, the solid content of the hydrophilic topcoat is 2-6.5%.

[0040] Exemplarily, the drying temperature is such that the surface temperature of the evaporator reaches 150-170° C. (preferably 160° C.) and the drying time is 10-20 minutes (preferably 10 minutes).

[0041] For example, the dry film thickness of the formed coating is 0.5-1.5 g / m 2 .

[0042] The technical solution of the present invention is described below with reference to some specific embodiments: Example 1 A low-odor, highly corrosion-resistant hydrophilic topcoat for automotive coatings has a raw material formula as shown in Table 1 below.

[0043] The production method of the hydrophilic topcoat for automobile coating comprises the following steps: (1) Add water to the pull cylinder, start the disperser, adjust the speed from slow to fast, and control the speed at 350 rpm; (2) Add vanadyl sulfate while stirring. After the vanadyl sulfate is completely dissolved and the solution becomes clear and transparent, continue stirring for 4 minutes. (3) Add ethylene-vinyl alcohol copolymer resin while stirring, and continue stirring for 4 minutes after the ethylene-vinyl alcohol copolymer resin is completely dissolved and the solution is visually clear and transparent; (4) Add ammonium zirconium carbonate while stirring, and continue stirring for 4 minutes after the ammonium zirconium carbonate is completely dissolved and the solution becomes clear and transparent. (5) Add isothiazolinone, an antifungal and antibacterial agent, under stirring. After the antifungal and antibacterial agent is completely dissolved and the solution is visually clear and transparent, continue stirring for 4 minutes to obtain the hydrophilic topcoat.

[0044] Table 1

[0045] Example 2 A low-odor, highly corrosion-resistant hydrophilic topcoat for automotive coatings, the raw material formula of which is shown in Table 1 above.

[0046] The production method of the hydrophilic topcoat for automobile painting is the same as that in Example 1.

[0047] Example 3 A low-odor, highly corrosion-resistant hydrophilic topcoat for automotive coatings, the raw material formula of which is shown in Table 1 above.

[0048] The production method of the hydrophilic topcoat for automobile painting is the same as that in Example 1.

[0049] Example 4 A low-odor, highly corrosion-resistant hydrophilic topcoat for automotive coatings, the raw material formula of which is shown in Table 1 above.

[0050] The production method of the hydrophilic topcoat for automobile painting is the same as that in Example 1.

[0051] Example 5 A low-odor, highly corrosion-resistant hydrophilic topcoat for automotive coatings, the raw material formula of which is shown in Table 1 above.

[0052] The production method of the hydrophilic topcoat for automobile painting is the same as that in Example 1.

[0053] Comparative Example 1 A commercially available hydrophilic topcoat for automobile evaporators was used: SURFALCOAT 1500-1.

[0054] Comparative Example 2 A low-odor, highly corrosion-resistant hydrophilic topcoat for automotive coatings, the raw material formula of which is shown in Table 1 above.

[0055] The production method of the hydrophilic topcoat for automobile painting is the same as that in Example 1.

[0056] Comparative Example 3 A low-odor, highly corrosion-resistant hydrophilic topcoat for automotive coatings, the raw material formula of which is shown in Table 1 above.

[0057] The production method of the hydrophilic topcoat for automobile painting is the same as that in Example 1.

[0058] The resulting topcoat product precipitates and cannot be used for subsequent coating applications.

[0059] Application of the above hydrophilic topcoat: Specifically, the hydrophilic topcoat is used for coating automobile air conditioners, comprising the following steps: Immerse the brazed automobile evaporator in the hydrophilic topcoat and spray or immerse for more than 30 seconds (make sure the inner and outer surfaces of the evaporator are completely exposed to the hydrophilic topcoat). Then take out the evaporator and dry the residual hydrophilic topcoat on the evaporator by blowing or centrifugation (make sure the final dry film weight reaches 0.5-1.5g / m 2 ), after drying (the evaporator surface temperature reaches 160℃ and maintains for 10 minutes) to form a film, and then cooled to room temperature, the treatment is completed.

[0060] During use, the hydrophilic topcoat of each embodiment does not need to overflow, so no waste liquid is generated, and the hydrophilic topcoat can be replenished into the treatment tank.

[0061] The performance test items and conditions of the above paint film are as follows: 1. Smell: Test method and conditions: During the actual operation of the air conditioner, directly smell the odor of the blown air.

[0062] The judgment criteria are shown in Table 2 below. The average score of the odor smelled by 10 odor tasters in the paint industry is taken.

[0063] Table 2

[0064] 2. Corrosion resistance: Corrosion resistance was tested using a 720-hour neutral salt spray test. Specifically, according to ASTM 8117, using a 5wt% sodium chloride solution at 35±2°C for 720 hours, the evaporator was removed from the salt spray chamber and immersed in 50-60°C distilled or deionized water for 10 minutes. The sample was then removed and dried in an 80°C oven for 2 hours, cooled to room temperature, and dropped from a height of 1 meter onto a clean steel table lined with white paper. The white powder removed from the evaporator was collected and weighed (mg). The ratio was calculated based on the expanded area of ​​the evaporator fins (denoted as S1): mg / S1.

[0065] 3. Drainage: Method: 1) Seal the external pipe of the evaporator with a water-proof cover to prevent water from entering the evaporator during the test and affecting the test results; Figure 1 In the water tank and equipment shown in a, place the evaporator at the angle (45°) required for actual use and measure the total weight of the evaporator and its hanging bracket in a dry state. 2) Fill the water tank with water and vibrate or stir to ensure that all outer surfaces of the evaporator are wetted. Then quickly lower the water tank. Do not touch or move the evaporator and suspension bracket during the drainage process. After 30 minutes, measure the weight of the evaporator and suspension bracket. 3) Test at least 6 evaporators; 4) Repeat the above test on the hanging bracket without the evaporator and measure its dry and wet weight as a benchmark; 5) Subtract the weight of water retained by the suspension bracket alone (difference between dry and wet states) from the total weight of water retained by the evaporator and suspension bracket (difference between dry and wet states) to obtain the weight of water retained by the evaporator; 6) Calculate the weight of retained water per unit volume of the evaporator. The volume of the evaporator is as follows: Figure 1 As shown in b (volume = effective length * effective width * effective height), it usually does not include the collecting pipe, external pipes, etc.

[0066] 4. Storage stability of hydrophilic topcoat: Store the hydrophilic topcoat at 5°C and 40°C for 3 months respectively, and observe the appearance of the hydrophilic topcoat to see if there are any abnormal conditions such as precipitation.

[0067] The above performance test results are shown in Table 3 below.

[0068] Table 3

[0069] In addition, in the corrosion resistance test, the corrosion conditions of the evaporators coated with the hydrophilic topcoat obtained in Example 1 and Comparative Example 1 after 480 hours of SST are as follows: Figure 2 and Figure 3 As shown in the figure, it can be seen that there is basically no corrosion in the evaporator fin area of ​​Example 1, and only at the manifold, where the brazing flux (affecting corrosion resistance) is less, white rust appears (such as Figure 2 As shown). In Comparative Example 1, the entire evaporator was severely corroded with white rust, and the corrosion rate reached 100% (as shown). Figure 3 shown).

[0070] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A low-odor, highly corrosion-resistant hydrophilic topcoat for automotive coating, characterized in that: The raw materials for forming the hydrophilic topcoat include the following components in parts by weight: 1-5 parts of film-forming resin, 1-5 parts of vanadyl sulfate, 0.1-1 parts of ammonium zirconium carbonate, 0.1-1 parts of auxiliary agent and 88-97.8 parts of water.

2. The hydrophilic topcoat according to claim 1, wherein The raw materials for forming the hydrophilic topcoat include the following components in parts by weight: 1-5 parts of film-forming resin, 1-3 parts of vanadyl sulfate, 0.1-0.5 parts of ammonium zirconium carbonate, 0.1-0.5 parts of auxiliary agent and 92-97.8 parts of water.

3. The hydrophilic topcoat according to claim 1 or 2, wherein The film-forming resin is selected from ethylene-vinyl alcohol copolymer resin.

4. The hydrophilic topcoat according to claim 1 or 2, wherein The auxiliary agent contains an antifungal and antibacterial agent.

5. The hydrophilic topcoat according to claim 4, wherein The mildew and antibacterial agent is selected from one or more of isothiazolinone, carbendazim and nano silver.

6. The method for preparing a hydrophilic topcoat according to any one of claims 1 to 5, wherein The steps include: Add vanadyl sulfate to the water under stirring. After the vanadyl sulfate is completely dissolved and the solution is visually clear, continue stirring for 3-5 minutes. Continue to add film-forming resin under stirring. After the film-forming resin is completely dissolved and the solution is visually uniform without precipitation, continue stirring for 3-5 minutes. While stirring, continue to add ammonium zirconium carbonate. After the ammonium zirconium carbonate is completely dissolved and the solution is visually uniform without precipitation, continue stirring for 3-5 minutes; While stirring, continue adding the additives. After all the additives are dissolved and the solution is visually uniform without precipitation, continue stirring for 3-5 minutes to obtain the hydrophilic topcoat.

7. The preparation method according to claim 6, characterized in that The stirring speed is 300-400 rpm.

8. Use of the hydrophilic topcoat as described in any one of claims 1 to 5 in the coating of automobiles.

9. The use according to claim 8, characterized in that In the application, the hydrophilic topcoat is used for coating automobile air conditioners.

10. The use according to claim 9, characterized in that The hydrophilic topcoat is applied on the surface of an automobile evaporator.

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