Degreasing agent suitable for zinc-aluminum-magnesium coated steel plate and application of degreasing agent

Abstract

The invention discloses a degreasing agent suitable for a zinc-aluminum-magnesium coated steel plate and application of the degreasing agent, and belongs to the technical field of metal surface pretreatment. The degreasing agent is a composition of a component A and a component B, wherein the component A comprises carbonate, hydroxide, chelate, silicate, phosphate, a masking agent and the like or an aqueous solution of a mixture of the carbonate, the hydroxide, the chelate, the silicate, the phosphate, the masking agent and the like; and the component B comprises a nonionic surfactant, a defoaming agent, a solubilizer, an emulsifier and the balance of pure water. The degreasing agent provided by the invention can be used for cleaning and removing oil dirt on the surface of a zinc-aluminum-magnesium plated steel plate material, has good compatibility with pollutants on the surfaces of other metal materials (such as cold-roll steel plates, galvanized steel plates and aluminum alloy plates) which are possibly subjected to collinear treatment, and is very suitable for being applied to the field of coating pretreatment of automobiles, parts and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface pretreatment, and in particular relates to a degreasing agent suitable for zinc-aluminum-magnesium coated steel plates and an application thereof. Background Art

[0002] Zinc-aluminum-magnesium coated steel plate is a new type of alloy coating material. Compared with ordinary galvanized coating, its composition and characteristics are as follows:

[0003] 1. Composition: The coating is primarily composed of three metallic elements: zinc, aluminum, and magnesium, and often contains small amounts of other elements such as silicon and copper. Different proportions give the material different performance characteristics.

[0004] 2. Features:

[0005] ① Corrosion resistance: Compared with traditional galvanized materials, zinc-aluminum-magnesium has better corrosion resistance. This is because the addition of aluminum and magnesium forms a denser and more stable protective film on the surface of the material, which can effectively block the intrusion of external oxygen, moisture and corrosive substances. For example, in marine climates or environments with severe industrial pollution, the service life of zinc-aluminum-magnesium materials is significantly longer than that of ordinary galvanized materials.

[0006] ② Self-repair ability: When the protective film on the surface of the material is locally damaged, the surrounding aluminum and magnesium elements will quickly migrate to the damaged area and re-form the protective film, thereby maintaining the corrosion resistance of the material;

[0007] ③Good processing performance: Zinc-aluminum-magnesium coated steel sheets have good processing performance and can be processed and formed through stamping, bending, welding and other processes. For example, in automobile body manufacturing, zinc-aluminum-magnesium sheets can be easily processed into various complex shapes to meet the needs of automobile design;

[0008] ④ High strength: Zinc-aluminum-magnesium coated steel sheets have higher strength than traditional automotive steel. This allows thinner sheets to be used when designing car bodies and structural parts, thereby reducing the weight of the entire vehicle and improving fuel economy. For example, a car body made of zinc-aluminum-magnesium sheets can reduce weight by 10%-20% compared to a traditional steel body, effectively reducing the car's energy consumption without compromising safety. At the same time, the high strength characteristics also enable the car to better absorb energy in the event of a collision, protecting the safety of passengers. The strength of zinc-aluminum-magnesium alloy is comparable to that of high-strength steel, and even performs better in some aspects, such as impact resistance, which can better withstand the impact force of a collision.

[0009] Based on the above characteristics, in recent years, zinc-aluminum-magnesium coated steel plate materials have been increasingly widely used in construction, photovoltaic new energy, automobile manufacturing and other fields. Major steel mills at home and abroad have also invested a lot of R&D and fixed asset costs in the development and production of related materials.

[0010] However, correspondingly, no new material is perfect. In the early stage of introduction into the industrial chain, it requires a period of improvement and running-in with downstream companies. In the actual application of zinc-aluminum-magnesium coated steel plates, there is still room for technical improvement in welding defects, surface degreasing and cleaning, and filiform corrosion after painting. The degreasing agent for zinc-aluminum-magnesium coated steel plates invented in this patent is precisely aimed at the defects of this material in surface degreasing and cleaning ( Figure 1 : The body zinc-aluminum-magnesium coating outer plate is in poor oil removal condition after degreasing; Figure 2 : A solution proposed to solve the problem of poor degreasing of the zinc-aluminum-magnesium coating on the car body (after electrophoresis).

[0011] The mechanism that leads to the degreasing and cleaning defects of zinc-aluminum-magnesium coated steel sheets is as follows:

[0012] 1. By analyzing the surface SEM images of zinc-aluminum-magnesium coated steel sheets and the energy spectrum data of the corresponding areas, it can be seen that the surface of the zinc-aluminum-magnesium coating is divided into a relatively flat zinc-rich phase area ( Figure 3 middle a), and the fingerprint-shaped Mg-Al-Zn-rich region ( Figure 3 (b) The fingerprint groove structure of the magnesium-aluminum-zinc-rich area will cause the specific surface area of the material to increase sharply, resulting in an increase in the material's physical adsorption capacity for oil products, thereby increasing the difficulty of cleaning and removing the oil products from the material surface; while the surface of traditional galvanized steel sheets only has a relatively flat zinc-rich phase area.

[0013] 2. The magnesium and aluminum elements on the surface of zinc-aluminum-magnesium coated steel plates are very active and exist in the form of oxides on the surface of the material ( Figure 4 : SEM image of the cross section of zinc-aluminum-magnesium coated steel plate), thereby increasing the polarity and adsorption of the material surface, and increasing the van der Waals force between the polar components in conventional oils (anti-rust oil, rolling oil) and the molecules of the plate surface material, making it more difficult to be cleaned and removed. Summary of the Invention

[0014] In response to the above-mentioned problems of oil removal and cleaning defects of zinc-aluminum-magnesium coated steel plates, the present invention provides a degreasing agent suitable for zinc-aluminum-magnesium coated steel plates and its application. By introducing ingredients such as alkali-sensitive material masking agents and unique small molecule non-ionic emulsifiers, the above problems can be greatly improved.

[0015] The technical solution adopted by the present invention is as follows: a degreasing agent suitable for zinc-aluminum-magnesium coated steel plates, wherein the degreasing agent is a two-component composition of A and B.

[0016] Preferably, the above-mentioned degreasing agent suitable for zinc-aluminum-magnesium coated steel plates, component A includes: carbonates, hydroxides, chelates, silicates, phosphates, masking agents, etc., or aqueous solutions of the above mixtures; component B includes: non-ionic surfactants, defoaming agents, solubilizers, emulsifiers, and the balance is pure water.

[0017] Preferably, the above-mentioned degreasing agent suitable for zinc-aluminum-magnesium coated steel plates comprises, by mass percentage:

[0018] Component A: 20-40% carbonate, 5-20% hydroxide, 1-10% chelate, 10-20% silicate, 5-10% phosphate, 1-5% masking agent, or an aqueous solution of a mixture thereof;

[0019] Component B: 20-30% nonionic surfactant, 10-20% defoaming agent, 1-5% solubilizer, 1-5% emulsifier, and the balance is pure water.

[0020] More preferably, the above-mentioned degreasing agent suitable for zinc-aluminum-magnesium coated steel plates, the carbonate in the A agent component is at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate; the hydroxide is at least one of sodium hydroxide and potassium hydroxide; the chelate is at least one of sodium gluconate, EDTA-4Na, EDTA-2Na, and sodium citrate; the silicate is at least one of sodium metasilicate, sodium orthosilicate, and potassium silicate; the phosphate is at least one of disodium hydrogen phosphate, sodium dihydrogen phosphate, trisodium phosphate, sodium pyrophosphate, and potassium pyrophosphate; the masking agent is at least one of sodium tartrate, ammonium fluoride, and silicone ketone. The nonionic surfactant in the B agent component is at least one of coconut alkyl quaternary amine ethoxylate, C9-13 alcohol ethoxylate, 2-propyl heptanol ethoxylate, and fatty alcohol alkoxylate; the defoaming agent is at least one of fatty alcohol polyoxyethylene polyoxypropylene ether, a three-dimensional silicone and polyether polyol technical mixture, and a polyether polyol nested product; the solubilizer is at least one of diethylene glycol butyl ether, C6 alkyl glucoside, and Tween 80; and the emulsifier is at least one of C10 alcohol ethoxylate, sodium polyacrylate, and polyoxyethylene hydrogenated castor oil.

[0021] More preferably, the above-mentioned degreasing agent suitable for zinc-aluminum-magnesium coated steel sheet, the siloxane ketone has the general structural formula shown as (I):

[0022]

[0023] Among them, n=1~5.

[0024] The invention discloses an application of a degreasing agent suitable for zinc-aluminum-magnesium coated steel plates in pre-degreasing and degreasing processes of metal surface treatment before coating.

[0025] Preferably, in the pre-degreasing and degreasing process, a degreasing agent is dissolved in industrial water to obtain a pre-degreasing and degreasing working solution; the content of the components in the pre-degreasing and degreasing working solution ranges, by mass percentage, as follows: 1.5-3.0% of component A and 1.0-2.0% of component B. The operating temperature range is 35-45°C.

[0026] The following is a method for removing oil from metal surfaces using a degreaser. A sample plate is cleaned using a degreaser suitable for zinc-aluminum-magnesium coated steel plates. The method includes the following steps:

[0027] 1) Prepare 2000mL of degreasing working solution according to the process requirements, test and adjust the process parameters according to the process requirements;

[0028] 2) Clean the sample with the adjusted degreasing working fluid (manual swing washing, 60 times per minute). The swing washing time is confirmed according to the process requirements, and then washed and dried.

[0029] The beneficial effects of the present invention are:

[0030] 1. By applying the degreasing agent of the present invention, the cleaning and oil removal efficiency of the surface of the zinc-aluminum-magnesium coated steel plate can be significantly improved, the defective rate during the use of the material can be reduced, and the related process costs can be reduced.

[0031] 2. The degreasing agent provided by the present invention can be prepared as a two-liquid component product. In practical applications, it can reduce the difficulty of adding materials and make it easier to disperse the pharmaceutical ingredients in the working fluid. It is particularly suitable for automatic feeding systems and can reduce labor costs in the production process.

[0032] 3. The degreasing agent provided by the present invention has good material compatibility and can cope with the situation where multiple plates and oil products are on the same line. In particular, it has great advantages in cleaning and degreasing the surface of zinc-aluminum-magnesium coated steel plates, which greatly promotes the application of zinc-aluminum-magnesium coated steel plate materials in automobile exterior panels and shortens the running-in time of this material in actual application scenarios and downstream processes.

[0033] 4. The degreasing agent provided by the present invention has less damage to alkali-sensitive materials (magnesium, aluminum alloy, etc.) due to its introduction of unique alkali-sensitive masking materials and small molecule non-ionic emulsifiers and other ingredients, which can improve the surface treatment quality of metal materials and reduce pre-treatment defects of coating.

[0034] 5. The degreasing agent provided by the present invention can enhance the anti-aging ability of the working fluid and prolong the use time due to its preferred solubilizer, chelating agent and emulsifier and other ingredients, thereby reducing the use cost of the agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The zinc-aluminum-magnesium coated outer panel of the vehicle body is in a poor state after degreasing.

[0036] Figure 2 The state of the zinc-aluminum-magnesium coated outer panel of the vehicle body after poor degreasing and electrophoresis.

[0037] Figure 3SEM images of the surface of the zinc-aluminum-magnesium coated steel plate and energy spectrum element analysis of the corresponding areas. a shows that the surface of the zinc-aluminum-magnesium coating is divided into a relatively flat zinc-rich phase area, and b shows a fingerprint-like magnesium-aluminum-zinc rich area.

[0038] Figure 4 SEM image of the cross-sectional structure of zinc-magnesium-aluminum coated steel plate.

[0039] Figure 5 The present invention relates to the state of the zinc-aluminum-magnesium coated outer panel of a vehicle body after the degreasing agent of the present invention is used. DETAILED DESCRIPTION

[0040] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0041] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0042] Example 1 A degreasing agent suitable for zinc-aluminum-magnesium coated steel sheets (1) A degreasing agent suitable for zinc-aluminum-magnesium coated steel plates

[0043] Preparation of degreasing agent:

[0044] Take 300g of potassium carbonate, 120g of potassium hydroxide, 50g of EDTA-2Na, 120g of sodium metasilicate, 50g of sodium pyrophosphate, and 20g of siloxane ketone, add pure water (conductivity ≤ 20μs / cm) to 1000g, and stir evenly to obtain degreasing component A;

[0045] Take 200g of C9-13 alcohol ethoxylate, 150g of fatty alcohol polyoxyethylene polyoxypropylene ether, 50g of C6 alkyl glycoside, and 50g of C10 alcohol ethoxylate, add pure water (conductivity ≤20μs / cm) to 1000g, and stir evenly to obtain a degreasing B component;

[0046] Siloxane ketone has the general structural formula shown as (I):

[0047]

[0048] Among them, n=1~5.

[0049] The degreasing component A and the degreasing component B are mixed evenly to obtain a degreasing agent suitable for zinc-aluminum-magnesium coated steel plates.

[0050] (2) A method for determining the degree of oil removal by a degreasing agent on a metal surface

[0051] 1) Prepare 2000mL of degreasing working solution according to the process requirements, test and adjust the process parameters according to the process requirements;

[0052] 2) The sample is repeatedly wiped with solvent (anhydrous ethanol) until constant weight is recorded as W1;

[0053] 3) Apply the specified oil stain (NR-320) to the weighed specimen, hang it on a specimen rack and drain for 20 minutes. Scrape off the oil droplets accumulated on the bottom of the specimen, place it at room temperature for 24 hours, and then weigh it again, recording it as W2;

[0054] 4) Clean the sample with the adjusted degreasing working solution obtained in step 1) (manual swing washing, 60 times per minute). The swing washing time is determined according to the process requirements. After washing and drying, weigh it again and record it as W3;

[0055] 5) Calculation:

[0056] 6) Perform three parallel tests. The absolute value of the difference between the results each time should not be greater than 2%. The arithmetic mean of the valid measurement results is taken as the measurement result. If there are less than two valid values, the test should be repeated.

[0057] This embodiment uses zinc-magnesium-aluminum sheet, galvanized sheet and aluminum alloy sheet of a certain vehicle manufacturer as samples for explanation.

[0058] The results of the embodiment were compared using a control group. The degreasing agent of the present invention suitable for zinc-aluminum-magnesium coated steel plates was group 1#, and a common degreasing agent commonly used by representative automobile OEMs was selected as group 2#. Each group cleaned 150 pieces of zinc-magnesium-aluminum plates, galvanized plates, and aluminum alloy plates (sample size: 150*70*0.8mm) in 2 liters of working fluid, including the following steps:

[0059] 1. Prepare 2000mL of degreasing working solution according to the process requirements, test and adjust the process parameters according to the process requirements. The parameters of the two groups of degreasing working solutions are shown in Table 1:

[0060] Table 1

[0061]

[0062] Note: Free alkalinity measurement method: Use a pipette to accurately transfer 10 ml of the bath solution to a conical flask, add 2-3 drops of phenolphthalein indicator to the conical flask and shake well. At this time, the solution is pink. Use a burette to add 0.1 N sulfuric acid to the conical flask, shaking while adding until the solution turns from pink to colorless. The number of milliliters of 0.1 N sulfuric acid consumed at this time is the free alkalinity of the bath solution, in pt.

[0063] 2. The sample was repeatedly wiped with pure alcohol until constant weight was obtained, which was recorded as W1 (due to the large number of samples, 1 sample was taken from every 5 samples for data collection, and 30 data points were obtained for each plate and each experimental group, the same below);

[0064] 3. Apply the specified oil stain (NR-320) to the weighed sample, hang it on the test piece rack and drain for 20 minutes, scrape off the oil droplets accumulated on the bottom of the test piece, place it at room temperature for 24 hours, and then weigh it again, record it as W2;

[0065] 4. Wash the sample with the adjusted degreasing working fluid (manual swing washing, 60 times per minute). The swing washing time is determined according to the process requirements. After washing and drying, weigh it again and record it as W3.

[0066] 5. Calculation:

[0067] (3) Effect

[0068] The two sets of experimental data are organized as Table 2 and Table 3:

[0069] Table 2

[0070]

[0071]

[0072] Table 3

[0073]

[0074] Figure 5 The following is a photo showing the degreasing performance of a degreasing agent suitable for zinc-magnesium-aluminum coated steel sheets on zinc-magnesium-aluminum materials. As can be seen from the figure, there are no defects on the zinc-magnesium-aluminum coated steel sheets after degreasing.

[0075] The data in Tables 2 and 3 show that the degreasing agent suitable for zinc-magnesium-aluminum coated steel plates has better temporal stability in the degreasing performance for zinc-magnesium-aluminum materials, as well as better degreasing performance for other materials (ordinary galvanized plates, aluminum plates, etc.), than conventional degreasing agents; especially for zinc-magnesium-aluminum materials, the degreasing agent of the present invention has obvious advantages and can greatly promote the application of zinc-magnesium-aluminum materials in the field of pre-treatment of coatings.

Claims

1. A degreasing agent suitable for zinc-aluminum-magnesium coated steel plates, characterized in that: The degreasing agent is a two-component composition of A and B. Component A includes: carbonates, hydroxides, chelates, silicates, phosphates, masking agents, etc., or aqueous solutions of the above mixtures; component B includes: non-ionic surfactants, defoamers, solubilizers, emulsifiers, and the balance is pure water.

2. A degreasing agent suitable for zinc-aluminum-magnesium coated steel sheets according to claim 1, characterized in that: Included by mass percentage: Component A: 20-40% carbonate, 5-20% hydroxide, 1-10% chelate, 10-20% silicate, 5-10% phosphate, 1-5% masking agent, or an aqueous solution of a mixture thereof; Component B: 20-30% nonionic surfactant, 10-20% defoaming agent, 1-5% solubilizer, 1-5% emulsifier, and the balance is pure water.

3. A degreasing agent suitable for zinc-aluminum-magnesium coated steel sheets according to claim 1 or 2, characterized in that: The carbonate in component A is at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate; the hydroxide is at least one of sodium hydroxide and potassium hydroxide; the chelate is at least one of sodium gluconate, EDTA-4Na, EDTA-2Na, and sodium citrate; the silicate is at least one of sodium metasilicate, sodium orthosilicate, and potassium silicate; the phosphate is at least one of disodium hydrogen phosphate, sodium dihydrogen phosphate, trisodium phosphate, sodium pyrophosphate, and potassium pyrophosphate; and the masking agent is at least one of sodium tartrate, ammonium fluoride, and silicone ketone.

4. The degreasing agent suitable for zinc-aluminum-magnesium coated steel sheets according to claim 3, characterized in that: The siloxane ketone has the general structural formula shown in (I): Among them, n=1~5.

5. A degreasing agent suitable for zinc-aluminum-magnesium coated steel sheets according to claim 1 or 2, characterized in that: The nonionic surfactant in component B is at least one of coconut alkyl quaternary amine ethoxylate, C9-13 alcohol ethoxylate, 2-propyl heptanol ethoxylate, and fatty alcohol alkoxylate; the defoamer is at least one of fatty alcohol polyoxyethylene polyoxypropylene ether, a three-dimensional silicone and polyether polyol technical mixture, and a polyether polyol nested product; the solubilizer is at least one of diethylene glycol butyl ether, C6 alkyl glucoside, and Tween 80; and the emulsifier is at least one of C10 alcohol ethoxylate, sodium polyacrylate, and polyoxyethylene hydrogenated castor oil.

6. Use of the degreasing agent for zinc-aluminum-magnesium coated steel sheets according to claim 1 or 2 in the pre-degreasing and degreasing processes of metal surface treatment before coating.

7. The use according to claim 6, characterized in that In the pre-degreasing and degreasing process, the degreasing agent according to claim 1 is dissolved in industrial water to obtain a pre-degreasing and degreasing working solution; the content range of each component in the pre-degreasing and degreasing working solution is as follows: component A is 1.5-3.0%, component B is 1.0-2.0%, and the operating temperature range is 35-45°C.

8. The use according to claim 6, characterized in that The method for cleaning a sample plate using the degreasing agent suitable for zinc-aluminum-magnesium coated steel plate according to claim 1 or 2 comprises the following steps: 1) Prepare 2000mL of degreasing working solution according to the process requirements, test and adjust the process parameters according to the process requirements; 2) Clean the sample with the adjusted degreasing working fluid, wash it manually at 60 times per minute. The washing time is determined according to the process requirements, and then wash and dry it.

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