Bottom-surface integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy and preparation method thereof

Abstract

The invention belongs to the technical field of coatings, and particularly relates to a bottom-surface integrated high-temperature paint for a vehicle-mounted magnesium-aluminum alloy and a preparation method of the bottom-surface integrated high-temperature paint. The bottom surface integrated high-temperature paint for the vehicle-mounted magnesium aluminum alloy is prepared from the following raw materials in percentage by mass: 10 to 20 percent of polyester resin, 3 to 6 percent of epoxy resin, 25 to 35 percent of epoxy modified acrylic resin, 4 to 7 percent of completely mixed etherified benzoyl melamine formaldehyde resin, 1 to 3 percent of polyester modified acid ester additive, 0.3 to 0.8 percent of acrylate flatting agent, 4 to 10 percent of solvent, 8 to 12 percent of filler and 20 to 25 percent of black paste. The bottom-surface integrated high-temperature paint has excellent interlayer adhesion to a magnesium-aluminum alloy base material, can ensure tight combination of a paint film and the base material, can effectively fill micropores and defects on the surface of the base material, and enhances the durability of a coating; the paint is high in spraying efficiency and has excellent recoatability, and an obtained paint film has excellent chemical resistance and appearance effect.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to a bottom-surface integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy and a preparation method thereof. Background Art

[0002] At present, the surface coatings used for automotive magnesium alloy materials on the market usually adopt a two-layer paint system of primer + topcoat, in which the main function of the primer is to provide interlayer adhesion between the magnesium-aluminum alloy material and the topcoat, and to fill and cover the surface voids of the magnesium-aluminum alloy substrate; however, the topcoat is far inferior to the primer in terms of adhesion and filling to the substrate, which leads to uneven performance of the overall coating; at the same time, if the primer is used as a topcoat, the chemical resistance, weather resistance and mechanical resistance of the primer often cannot meet the strict standards of the automotive industry, especially in extreme environments such as high temperature and high humidity, the primer is prone to peeling, fading and other problems. In addition, the traditional two-layer paint system has many inconveniences during the construction process. Spraying primer and topcoat needs to be carried out separately, which not only increases the complexity of the operation, but also easily leads to mixing errors and reduces the spraying efficiency. At the same time, the use of a two-layer paint system increases the emission of organic solvents, which not only increases costs, but also creates an additional burden on the environment.

[0003] Therefore, it is necessary to develop an integrated high-temperature paint for the bottom surface of automotive magnesium-aluminum alloy. During the spraying process, the integrated high-temperature paint can save the need to spray a layer of primer and a layer of paint. It can not only solve the shortcomings of the traditional two-layer paint system, but also provide better performance and higher construction efficiency, and can effectively respond to market demand. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a bottom-integrated high-temperature paint for automotive magnesium-aluminum alloy, which has excellent interlayer adhesion to the magnesium-aluminum alloy substrate, can ensure the close bonding between the paint film and the substrate, and can effectively fill the micropores and defects on the surface of the substrate to enhance the durability of the coating; it has high spraying efficiency and excellent recoatability, and the obtained paint film has excellent chemical resistance and appearance effect.

[0005] The technical solution adopted by the present invention to solve the above problems is as follows:

[0006] A high-temperature paint for the bottom surface of a vehicle-mounted magnesium-aluminum alloy comprises the following raw materials in percentage by mass: 10-20% polyester resin, 3-6% epoxy resin, 25-35% epoxy-modified acrylic resin, 4-7% fully mixed etherified benzoguanamine formaldehyde resin, 1-3% polyester-modified acid ester auxiliary agent, 0.3-0.8% acrylic ester leveling agent, 4-10% solvent, 8-12% filler and 20-25% black paste.

[0007] Preferably, the polyester resin is KN8320-70. The selected polyester resin has excellent interlayer adhesion and good chemical resistance.

[0008] Preferably, the epoxy resin is 901-75. The selected epoxy resin can improve the adhesion to the substrate and improve the salt spray resistance.

[0009] Preferably, the epoxy-modified acrylic resin is ZJ-103. The selected epoxy-modified acrylic resin has the advantages of good corrosion resistance, good salt spray resistance, good chemical resistance, etc., and also has excellent interlayer adhesion.

[0010] Preferably, the completely mixed etherified benzoguanamine formaldehyde resin is 1123. The selected fully mixed etherified benzoguanamine formaldehyde resin can give the paint layer excellent adhesion.

[0011] Preferably, the polyester modified acid ester additive is Z2063. The selected polyester modified acid ester additive helps to improve salt spray resistance and water resistance.

[0012] Preferably, the acrylic leveling agent is BYK358.

[0013] Preferably, the solvent comprises butyl acetate and isobutyl alcohol in a mass ratio of (2-5):(2-5).

[0014] Preferably, the filler is ultrafine barium sulfate. The selected filler is conducive to improving the filling property of the substrate.

[0015] Preferably, the preparation method of the bottom integrated high-temperature paint for automotive magnesium-aluminum alloy comprises the following steps: adding polyester resin, epoxy-modified acrylic resin, completely mixed etherified benzoguanamine formaldehyde resin, epoxy resin, polyester-modified acid ester additive, acrylic ester leveling agent, solvent, and filler in sequence according to the formula mass percentage, stirring evenly at a speed of 200 r / min, and then adding black slurry and stirring at a speed of 800 r / min for 30 minutes.

[0016] Preferably, the black paste comprises the following raw materials in percentage by mass: 25-35% propylene glycol methyl ether acetate, 5-10% pigment dispersant, 20-40% polyester resin, 0.5-3% dispersing anti-settling agent, 10-15% carbon black powder, and 8-18% ultrafine zinc phosphate.

[0017] Preferably, the pigment dispersant is BYK-163.

[0018] Preferably, the polyester resin is KN8320-70.

[0019] Preferably, the dispersing and anti-settling agent is Dispers 9283.

[0020] Preferably, the carbon black powder is 6# carbon powder.

[0021] In addition, the selected ultrafine zinc phosphate helps to improve salt spray resistance.

[0022] Preferably, the preparation method of the black slurry comprises the following steps: adding propylene glycol methyl ether acetate, pigment dispersant, and polyester resin in sequence according to the mass percentage of the formula, and stirring at a speed of 300 r / min for 10 minutes; then adding a dispersing anti-settling agent, carbon black powder, and ultrafine zinc phosphate in sequence, and stirring at a speed of 600 r / min for 30 minutes; then transferring to a sand mill to grind the black slurry to a fineness of 10 μm.

[0023] The present invention also provides a method for using the bottom-integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy, comprising: evenly mixing the bottom-integrated high-temperature paint and a diluent in a weight ratio of 10:5-7, controlling the viscosity at 12-14 seconds (Yantian 2# cup), spraying it on a magnesium-aluminum alloy substrate, and then baking and curing to obtain a paint film.

[0024] Preferably, the diluent comprises the following components in percentage by mass: 25% to 35% butyl acetate, 8% to 12% ethyl acetate, 20% to 30% methyl isobutyl ketone, 8% to 12% isobutyl alcohol, and 20% to 30% propylene glycol methyl ether acetate.

[0025] More preferably, the diluent comprises the following components in percentage by mass: 30% butyl acetate, 10% ethyl acetate, 25% methyl isobutyl ketone, 10% isobutyl alcohol, and 25% propylene glycol methyl ether acetate.

[0026] Preferably, the baking conditions are: 150° C., 30 to 40 minutes.

[0027] Preferably, the paint film has a thickness of 25 to 75 μm.

[0028] The present invention has the following beneficial effects:

[0029] The present invention has developed a bottom-to-top integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloys through in-depth analysis of the performance requirements and construction requirements of vehicle-mounted magnesium-aluminum alloys, combined with the characteristics of existing raw materials on the market, and after repeated experiments and formula optimization. Compared with the traditional two-layer paint system, the bottom-to-top integrated high-temperature paint of the present invention does not require separate spraying of primer and topcoat, which simplifies the construction process and improves the spraying efficiency; in the preparation process, the present invention uses low-VOC (volatile organic compound) solvents to reduce the emission of organic solvents and meet environmental protection requirements.

[0030] The present invention selects epoxy resin, epoxy-modified acrylic resin, polyester resin and amino resin as the main resins of the paint, wherein the introduction of epoxy resin gives the paint film good adhesion and chemical properties; the epoxy-modified acrylic resin improves the chemical properties, drying speed and hardness of the paint film, while optimizing the pigment arrangement, making the paint film surface more uniform and beautiful; the addition of amino resin enhances the adhesion, flexibility and water boiling resistance of the paint film, while greatly improving the mechanical properties of the paint film, effectively resisting external impact and wear.

[0031] The bottom-surface integrated high-temperature paint of the present invention has excellent interlayer adhesion to the magnesium-aluminum alloy substrate, can ensure the close bonding between the paint film and the substrate, and can effectively fill the micropores and defects on the surface of the substrate to enhance the durability of the coating; it has high spraying efficiency and excellent recoatability, and the obtained paint film has excellent chemical resistance and appearance effect, and is suitable for vehicle-mounted parts made of magnesium-aluminum alloy. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and technical advantages to be solved by the present invention clearer, the following will be described in detail with reference to specific examples, but the protection scope of the present invention is not limited to the following specific embodiments, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, and are not limitations of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0033] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0034] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0035] The amounts of the components of the bottom-to-bottom integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy in Examples 1-3 are shown in Table 1 below.

[0036] Table 1:

[0037]

[0038] Among them, the formula of the semi-finished black paste in the bottom integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy in Examples 1-3 is shown in Table 2 below.

[0039] Table 2:

[0040]

[0041] The preparation method of the black slurry in specific embodiments 1-3 includes the following steps: adding propylene glycol methyl ether acetate, pigment dispersant, and polyester resin in sequence according to the mass percentage of the formula, and stirring at a speed of 300 r / min for 10 minutes; then adding a dispersing anti-settling agent, carbon black powder, and ultrafine zinc phosphate in sequence, and stirring at a speed of 600 r / min for 30 minutes; then transferring to a sand mill to grind the black slurry to a fineness of 10 μm.

[0042] Specifically, the preparation method of the bottom integrated high-temperature paint for automotive magnesium-aluminum alloy in Examples 1-3 includes the following steps: adding polyester resin, epoxy-modified acrylic resin, fully mixed etherified benzoguanamine formaldehyde resin, epoxy resin, polyester-modified acid ester additive, acrylic ester leveling agent, solvent, and filler in sequence according to the mass percentage of the formula, stirring evenly at a speed of 200 r / min, and then adding black slurry and stirring at a speed of 800 r / min for 30 minutes.

[0043] Preparation of a diluent: 30 wt % of butyl acetate, 10 wt % of ethyl acetate, 25 wt % of methyl isobutyl ketone, 10 wt % of isobutyl alcohol, and 20 wt % of propylene glycol methyl ether acetate are uniformly mixed to obtain a diluent.

[0044] The automotive magnesium-aluminum alloy bottom integrated high-temperature paint and thinner are mixed in a weight ratio of 10:6, and the oil is opened. The viscosity is 13 seconds (Yantian 2# cup), and then it is sprayed on the automotive magnesium alloy substrate and dried. The baking conditions are 150℃*40 minutes.

[0045] In order to evaluate the technical effect of the present invention, the following performance tests were performed on the products of Examples 1-3:

[0046] 1. Construction application evaluation: Examples 1-3 are all suitable for construction, and the appearance of the paint film and the suitability of the drying conditions during construction.

[0047] 2. Appearance: The surface glossiness of the samples of Examples 1-3 is 3.5-4.5° (60° angle), with good leveling and fine flatness.

[0048] 3. Film thickness: The paint film thickness on the surface of the samples of Examples 1-3 is 25 to 75 microns.

[0049] 4. Scratch resistance: The sample was tested under a load of 10N and a test needle according to the Bosch standard (needle tip is 0.75 mm), using a 318 hardness pen (Erichsen) or a hardness pen with equivalent performance, and the scratch length was at least 50 mm. After the test, the surface of the sample of Examples 1-3 had no coating shedding or cracking, no scratches on the substrate, and no defects when touched.

[0050] 5. High temperature alternation: Take the samples of Examples 1-3 and perform 20 cycles of high and low temperature alternation tests under the following conditions.

[0051] High and low temperature alternating conditions: temperature 23℃*30% humidity for 40min; humidity 30%, temperature from 23℃ to -35℃, time 90min; -35*30% for 60min; humidity 80%, temperature rise to 50℃, time 80min; 50℃*80% for 120min; 30% humidity rise to 80℃, time 30min; 80℃ for 240 hours; 30% humidity cool to 23℃, time 60min. This is one cycle. After the test, the appearance of the samples of Examples 1-3 did not change significantly, and the surface paint film met the requirements of adhesion level 1 and scratch resistance.

[0052] 6. Condensation water test: Take samples of Examples 1-3 and test them according to the constant humidity condensation test method specified in standard ISO 6270-2, at a temperature of 40±3°C and a test time of 240 hours. After the experiment, leave them at room temperature for 30 minutes. There is no bubbling in Examples 1-3, and there is no obvious change in appearance. The surface paint film meets the requirements of adhesion level 1 and scratch resistance.

[0053] 7. Light aging resistance: The samples of Examples 1-3 were tested for 500 hours under the conditions of radiation intensity of 1.2 W / ㎡, black mark temperature of 100°C, and relative humidity of 50% RH; after the test, the samples of Examples 1-3 had no obvious color change, cracking or other undesirable phenomena, the gray card grade was ≥4, and the surface paint film met the requirements of adhesion level 1 and scratch resistance.

[0054] 8. Hydrolysis resistance: 90°C*96%RH*72 hours. After the test, the appearance of the samples of Examples 1-3 had no obvious change, the paint film had no bubbling, and met the adhesion level 1 and scratch resistance requirements.

[0055] 9. Wet and dry abrasion resistance: After fixing the test sample, conduct 100 friction tests, using a wet friction white cloth (105F09 model). The friction head diameter (16mm) test head; load 9N, 60 times / min, 100 times, the paint film gray level ≥ 4.

[0056] 10. Chemical resistance test: Use a pipette to drop 0.1 ml of 99.5% alcohol on the surface of the samples of Examples 1-3. After 10 minutes, observe the surface of the paint film. After the test, there is no obvious change in the paint film of the samples of Examples 1-3, and the gray level of the test cloth is ≥3.

[0057] 11. Hand cream and sunscreen resistance test: Hand cream and sunscreen set model: PM001, manufacturer: Dr.schroder Cosmetica Gmbh Co. (Gauze model: REF60003 (yarn number is 20), manufacturer: LEINA-WERKE Gmbh; Take the samples of Examples 1-3, cover the surface of the samples with a layer of special gauze, and evenly apply the special hand cream and sunscreen respectively, and keep the samples at 80°C for 24 hours. Take out and cool to room temperature, clean the oil stains on it, and there is no obvious change in the appearance of the samples of Examples 1-3 after the test, and the paint film meets the requirements of adhesion level 1 and scratch resistance.

[0058] 12. Prohibited substances: Meet ROSH 10 requirements.

[0059] 13. Salt spray resistance test: The samples of Examples 1-3 were tested in a salt spray chamber under the following test conditions: 45°C, neutral salt spray, 96 hours. After the test, the samples of Examples 1-3 had no red rust or white rust, and the coating had no blistering, peeling, cracking, etc., and the unilateral corrosion at the scratch was ≤2mm.

[0060] 14. Hardness: Use a 2H hardness of a Chinese pencil (UNI series) at an angle of 45° and a load of 1000g to draw three lines of 3-5 cm in different directions on the surface of the samples of Examples 1-3; after the test, there is no obvious scratch on the surface paint film of the samples of Examples 1-3.

[0061] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0062] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0063] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A bottom-integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy, characterized in that: The invention comprises the following raw materials in percentage by mass: 10-20% polyester resin, 3-6% epoxy resin, 25-35% epoxy modified acrylic resin, 4-7% completely mixed etherified benzoguanamine formaldehyde resin, 1-3% polyester modified acid ester auxiliary agent, 0.3-0.8% acrylic ester leveling agent, 4-10% solvent, 8-12% filler and 20-25% black pulp.

2. The bottom-surface integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy according to claim 1, characterized in that: The solvent comprises butyl acetate and isobutyl alcohol in a mass ratio of (2-5):(2-5).

3. The bottom-surface integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy according to claim 1, characterized in that: The epoxy modified acrylic resin is ZJ-103.

4. The bottom-surface integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy according to claim 1, characterized in that: The completely mixed etherified benzoguanamine formaldehyde resin is 1123.

5. The bottom-surface integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy according to claim 1, characterized in that: The polyester modified acid ester auxiliary agent is Z2063.

6. The bottom-surface integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy according to claim 1, characterized in that: The filler is ultrafine barium sulfate.

7. The bottom-surface integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy according to claim 1, characterized in that: The black paste comprises the following raw materials in percentage by mass: 25-35% propylene glycol methyl ether acetate, 5-10% pigment dispersant, 20-40% polyester resin, 0.5-3% dispersing anti-settling agent, 10-15% carbon black powder, and 8-18% superfine zinc phosphate.

8. The bottom-surface integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy according to claim 7, characterized in that: The preparation method of the black slurry comprises the following steps: adding propylene glycol methyl ether acetate, a pigment dispersant, and a polyester resin in order according to the mass percentage of the formula, and stirring at a speed of 300 r / min for 10 minutes; then adding a dispersing anti-settling agent, carbon black powder, and ultrafine zinc phosphate in order, and stirring at a speed of 600 r / min for 30 minutes; then transferring to a sand mill to grind the black slurry to a fineness of 10 μm.

9. The method for preparing the bottom-integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: adding polyester resin, epoxy modified acrylic resin, completely mixed etherified benzoguanamine formaldehyde resin, epoxy resin, polyester modified acid ester auxiliary agent, acrylic ester leveling agent, solvent and filler in sequence according to the mass percentage of the formula, stirring evenly at a speed of 200 r / min, then adding black slurry and stirring at a speed of 800 r / min for 30 minutes.

10. A method for using the bottom-integrated high-temperature paint for vehicle-mounted magnesium-aluminum alloy according to any one of claims 1 to 8, characterized in that: include: The bottom-surface integrated high-temperature paint and the thinner are evenly mixed in a weight ratio of 10:5-7, the viscosity is controlled at 12-14 seconds (Yantian 2# cup), and then sprayed on the magnesium-aluminum alloy substrate, and then baked and cured to obtain a paint film.

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