Anti-adhesion anti-after-tack water-based metallic paint and preparation method thereof

Abstract

The invention relates to anti-adhesion and anti-after-tack water-based metallic paint and a preparation method thereof. The water-based metallic paint comprises the following raw materials: (a) water-based acrylate polymer emulsion; (b) titanium dioxide; (c) silica powder; (d) cobalt naphthenate; (e) trimethylolpropane diallyl ether; (f) methyl ethyl ketone peroxide; (g) a dispersant; (h) a defoaming agent; (i) a filler. The aqueous metallic paint of the present invention can exhibit high pigment loading and good anti-blocking (anti-bonding) properties and anti-after-tack properties, and thus substrates having a paint film formed from the aqueous metallic paint composition exhibit a good masking effect and can be stacked together within a very short time after the metallic paint composition is applied and cured.

Description

Technical Field

[0001] The present invention relates to the field of coatings, in particular to an anti-adhesion and anti-re-adhesion water-based metallic paint and a preparation method thereof. Background Art

[0002] When steel is exposed to air, it will form a rust layer on the surface due to the attack of water vapor and oxygen, which will affect the service life of the steel. There is a considerable amount of time between the steel mill and the user, so steel will more or less rust.

[0003] Water-based metallic paint has a shimmering effect due to the presence of aluminum powder, copper powder, pearlescent pigments, etc. It is widely used in the coating of metal surfaces such as building exterior walls, steel structures, and concrete facilities, creating a metallic decorative effect. However, existing water-based metallic paint coatings are prone to adhesion after being heated. During the proofing stage, when the sample coating is completely dried and protected during storage and transportation, the coatings adhere together when stacked face to face or back to back, causing partial or complete damage to the coating and making it impossible to accurately confirm the sample effect. During the large-scale application stage, water-based metallic paint coatings are prone to re-adhesion after being heated in high-temperature seasons, causing dirt absorption and difficulty in cleaning. The coating gloss is reduced, and the decorative effect is reduced, which restricts the further promotion and application of water-based metallic paint. Summary of the Invention

[0004] The present invention aims to overcome the aforementioned shortcomings of the prior art by providing a water-based metallic paint that is anti-adhesive and anti-re-adhesive, and a method for preparing the same. The water-based metallic paint of the present invention prevents coating damage caused by adhesion, and even when applied over large areas, exhibits no re-adhesion after exposure to high temperatures, without significant gloss loss, effectively maintaining the metallic decorative effect of the coating.

[0005] The present invention solves the above technical problems through the following technical solutions:

[0006] The present invention provides a water-based metallic paint with anti-adhesion and anti-re-adhesion properties, the raw materials of which include:

[0007] (a) Water-based acrylic polymer emulsion; (b) titanium dioxide; (c) silica powder; (d) cobalt naphthenate; (e) trimethylolpropane diallyl ether; (f) methyl ethyl ketone peroxide; (g) dispersant; (h) defoaming agent; (i) filler;

[0008] Wherein, the water-based acrylic polymer emulsion is obtained by the following preparation method:

[0009] (1) mixing deionized water, an emulsifier, methacrylic acid, n-butyl acrylate, styrene, and trimethylolpropane diallyl ether to obtain a core layer pre-emulsion;

[0010] (2) mixing deionized water, an emulsifier, methyl methacrylate, n-butyl acrylate, methacrylic acid, and trimethylolpropane diallyl ether to obtain a shell pre-emulsion;

[0011] (3) adding ammonia water, core layer pre-emulsion and initiator to a mixture of deionized water and emulsifier in sequence, and heating the mixture to react; then adding shell layer pre-emulsion and initiator, and keeping the mixture warm to react;

[0012] (4) adding tert-butyl hydroperoxide and sodium formaldehyde sulfoxylate in sequence and carrying out sufficient reaction; adjusting the pH value of the emulsion to a weak alkaline state to obtain a water-based acrylic polymer emulsion;

[0013] The ratio of the sum of the mass of the titanium dioxide and the silicon powder to the mass of the polymer in the water-based acrylic polymer emulsion is 6.0-7.0.

[0014] Preferably, the mass fraction of the polymer in the water-based acrylic ester polymer emulsion is 40-50%.

[0015] In the preparation method of the water-based acrylic polymer emulsion, the pH value of the emulsion is preferably adjusted by adding ammonia water in step (4). In step (4), the pH value of the weak alkalinity is preferably 7.1-7.5. In step (4), the time for full reaction is preferably 60-90 minutes. In step (3), the temperature of the temperature-raising reaction is preferably 65-75°C, and the reaction time is preferably 30-60 minutes; the time for the heat-insulating reaction is preferably 60-90 minutes. In step (4), the time for full reaction is preferably 90-120 minutes. The emulsifier is preferably at least one of allyloxy fatty alcohol oxyethylene ether sulfate, dodecylbenzene sulfonate, alkylphenol polyoxyethylene ether sulfate, and nonylphenol ethoxylate. The initiator is preferably ammonium persulfate, sodium persulfate, or potassium persulfate. The filler is preferably aluminum powder, copper powder, or pearlescent pigment.

[0016] A second aspect of the present invention provides a method for preparing an anti-blocking and anti-re-adhesive water-based metallic paint, which comprises the following steps: mixing various raw materials to obtain the water-based metallic paint.

[0017] In this specification, the term "water-based" means that water is used as a solvent, diluent or dispersion medium in the topcoat composition. Water-based coatings include water-soluble coatings, water-dilutable coatings and water-dispersible coatings, etc. The anti-blocking water-based topcoat composition may not contain volatile organic solvents, or it may contain a small amount of volatile organic solvents or cosolvents to improve the overall performance of the coating. For example, the water-based acrylate polymer emulsion according to the present invention can be adjusted to contain a small amount (e.g., 0 to 5 wt%) or even no volatile organic solvents (i.e., VOCs). In this case, the water-based metallic paint of the present invention will hardly release harmful gases (e.g., formaldehyde) and therefore will not affect the health of consumers or industrial workers. In other words, it is an environmentally friendly "green" product.

[0018] As used herein, the term "anti-blocking" means that paint films formed from the metallic paint composition do not readily adhere to one another, or that two contacting paint films can be easily separated. Consequently, substrates (e.g., panels or frames) coated with the anti-blocking water-based metallic paint can be stacked together very quickly after application and curing of the topcoat composition, thereby shortening processing time during production.

[0019] As used herein, the term "water-based acrylate polymer" refers to a water-based polymer produced by emulsion (co)polymerization of specific acrylic monomers, either alone or optionally with one or more comonomers. Water-based acrylate polymers are important film-forming materials and determine key properties of coating films, such as anti-blocking properties and the ability to support specific pigments.

[0020] The present invention adopts a water-based acrylic polymer emulsion prepared by a specific method, and then combines it with a high amount of titanium dioxide and silicon powder to construct a relatively rough coating surface, greatly reducing the contact area between the coatings, which is beneficial to improving the anti-adhesion performance of the coating.

[0021] Compared with the prior art, the present invention has the following advantages: the water-based metallic paint of the present invention can exhibit a high pigment loading and good anti-blocking (anti-adhesion) and anti-re-sticking properties, so that substrates having a paint film formed from the water-based metallic paint composition exhibit good hiding effects and can be stacked together within a very short time after the metallic paint composition is applied and cured. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to specific embodiments.

[0023] Example 1

[0024] Prepare the emulsion: add deionized water and emulsifier (allyloxy fatty alcohol oxyethylene ether sulfate) into a flask and stir evenly, then add styrene, n-butyl acrylate, trimethylolpropane diallyl ether, and methacrylic acid in turn and stir for 30 minutes to obtain a core layer pre-emulsion. Let it stand for 20 minutes without stratification and then use it.

[0025] Deionized water and an emulsifier (allyloxy fatty alcohol oxyethylene ether sulfate) were added into a flask and stirred evenly, and then methyl methacrylate, n-butyl acrylate, methacrylic acid, and trimethylolpropane diallyl ether were added in sequence and stirred to obtain a shell pre-emulsion.

[0026] Deionized water and an emulsifier (allyloxy fatty alcohol oxyethylene ether sulfate) were added to a four-necked flask equipped with a condenser coil and a stirring device. The temperature was raised to 70°C with stirring. Ammonia water, the core layer pre-emulsion, and an initiator (ammonium persulfate) were then added in sequence. The reaction was continued at 70°C for 30 minutes. The shell layer pre-emulsion and initiator (ammonium persulfate) were then slowly added and the reaction was maintained at this temperature for 60 minutes.

[0027] Then, tert-butyl hydroperoxide and sodium formaldehyde sulfoxylate were added sequentially and allowed to react for 90 minutes. The emulsion was cooled to 40°C and the pH was adjusted to a weakly alkaline pH of 7.1 by adding ammonia. Deionized water was then added to adjust the solids content to obtain a water-based acrylic polymer emulsion. The mass fraction of the polymer in the emulsion was 50%.

[0028] 50 g of the above-mentioned water-based acrylic polymer emulsion, 20 g of titanium dioxide, 130 g of silica powder, 1 g of cobalt cyclohexane, 3 g of trimethylolpropane diallyl ether, 1 g of methyl ethyl ketone peroxide, 0.5 g of dispersant, 0.5 g of defoamer, and 14 g of pearlescent pigment were mixed to obtain a water-based metallic paint.

[0029] Example 2

[0030] Prepare the emulsion: add deionized water and emulsifier (dodecylbenzenesulfonate) into a flask and stir evenly, then add styrene, n-butyl acrylate, trimethylolpropane diallyl ether, and methacrylic acid in sequence and stir for 30 minutes to obtain a core layer pre-emulsion, let it stand for 20 minutes without stratification and then set aside.

[0031] Deionized water and an emulsifier (dodecylbenzenesulfonate) were added into a flask and stirred evenly, and then methyl methacrylate, n-butyl acrylate, methacrylic acid, and trimethylolpropane diallyl ether were added in sequence and stirred to obtain a shell pre-emulsion.

[0032] Deionized water and an emulsifier (dodecylbenzenesulfonate) were added to a four-necked flask equipped with a condenser coil and a stirring device. The temperature was raised to 70°C with stirring. Ammonia water, the core layer pre-emulsion, and an initiator (sodium persulfate) were then added in sequence. The reaction was continued at 70°C for 30 minutes. The shell layer pre-emulsion and initiator (sodium persulfate) were then slowly added and the reaction was maintained at this temperature for 60 minutes.

[0033] Then, tert-butyl hydroperoxide and sodium formaldehyde sulfoxylate were added sequentially and allowed to react for 90 minutes. The emulsion was cooled to 40°C and the pH was adjusted to a weakly alkaline pH of 7.3 by adding ammonia. Deionized water was then added to adjust the solids content to obtain a water-based acrylic polymer emulsion. The mass fraction of the polymer in the emulsion was 40%.

[0034] Mix 50 g of the above-mentioned water-based acrylic polymer emulsion, 20 g of titanium dioxide, 120 g of silica powder, 1 g of cobalt cyclohexane, 5 g of trimethylolpropane diallyl ether, 1 g of methyl ethyl ketone peroxide, 0.5 g of dispersant, 0.5 g of defoamer, 5 g of copper powder, and 5 g of pearlescent pigment to obtain a water-based metallic paint.

[0035] Comparative Example 1

[0036] A water-based metallic paint was prepared by mixing 50 g of a commercially available water-based acrylic polymer emulsion (ROSF-911, purchased from Guangzhou Rosf New Material Technology Co., Ltd., which is copolymerized with styrene and acrylic acid ester, with a polymer mass fraction of 50%), 20 g of titanium dioxide, 100 g of silica powder, 1 g of cobalt naphthenate, 3 g of trimethylolpropane diallyl ether, 1 g of methyl ethyl ketone peroxide, 0.5 g of a dispersant, 0.5 g of a defoamer, 5 g of copper powder, and 5 g of a pearlescent pigment.

[0037] Technical effect testing

[0038] Anti-adhesion test: 3 groups of test pieces (10 pieces in each group) were made of pine wood, PVC and aluminum respectively, and the size of the test pieces was 1m×0.1m×0.02m. The metallic paint composition prepared as above was sprayed on both sides of each test piece to form a film with a wet film thickness of 150 microns. Subsequently, the coated test pieces were subjected to 20 minutes of rapid drying and then to a final drying for 12 hours. Next, drying time pieces made of the same material were stacked one by one and a 10kg weight was added on top of them. After 72 hours, the weight was removed and the test pieces were visually observed to evaluate their surface adhesion. The test parameters and results are listed in the table below.

[0039]

[0040] The results show that the water-based metallic paints of Examples 1 and 2 of the present invention exhibit good anti-blocking properties on wood, plastic, and metal substrates, allowing them to be stacked very quickly after production. In contrast, the metallic paint of Comparative Example 1 exhibited severe blocking, with the paint film completely tearing.

[0041] Hiding Power Test: Three groups of test specimens (10 each) were prepared using pine wood, PVC, and aluminum, respectively. The specimens measured 1 m x 0.1 m x 0.02 m. The metallic paint composition prepared above was knife-coated onto each specimen to a wet film thickness of 100 microns. The coated specimens were then dried at room temperature and 50% relative humidity for 12 hours. After drying, the coating's hiding power was tested according to GB / T 1726: Testing Method for Hiding Power of Coatings.

[0042] Pine wood hiding power PVC covering power Al substrate hiding power Example 1 93 92 93 Example 2 94 93 93

[0043] It can be seen from the above results that the metallic paint of the present invention can achieve a hiding power of more than 90%, thus showing excellent technical effects in practice.

[0044] It must be emphasized that the above detailed description is a specific description of a feasible embodiment of the present invention, but the embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the technical spirit of the present invention should be included in the patent scope of the present invention.

Claims

1. A water-based metallic paint with anti-adhesion and anti-re-adhesion properties, the raw materials of which include: (a) Water-based acrylic polymer emulsion; (b) titanium dioxide; (c) silica powder; (d) cobalt naphthenate; (e) trimethylolpropane diallyl ether; (f) methyl ethyl ketone peroxide; (g) dispersant; (h) defoaming agent; (i) filler; Wherein, the water-based acrylic polymer emulsion is obtained by the following preparation method: (1) mixing deionized water, an emulsifier, methacrylic acid, n-butyl acrylate, styrene, and trimethylolpropane diallyl ether to obtain a core layer pre-emulsion; (2) mixing deionized water, an emulsifier, methyl methacrylate, n-butyl acrylate, methacrylic acid, and trimethylolpropane diallyl ether to obtain a shell pre-emulsion; (3) adding ammonia water, core layer pre-emulsion and initiator to a mixture of deionized water and emulsifier in sequence, and heating the mixture to react; then adding shell layer pre-emulsion and initiator, and keeping the mixture warm to react; (4) adding tert-butyl hydroperoxide and sodium formaldehyde sulfoxylate in sequence and carrying out sufficient reaction; adjusting the pH value of the emulsion to a weak alkaline state to obtain a water-based acrylic polymer emulsion; The ratio of the sum of the mass of the titanium dioxide and the silicon powder to the mass of the polymer in the water-based acrylic polymer emulsion is 6.0-7.

0.

2. The water-based metallic paint according to claim 1, wherein the mass fraction of the polymer in the water-based acrylic ester polymer emulsion is 40-50%.

3. The water-based metallic paint as claimed in claim 1, wherein the pH value of the emulsion is adjusted in step (4) by dropwise addition of ammonia water.

4. The water-based metallic paint according to claim 1, wherein in step (4), the pH value of the weak alkalinity is preferably 7.1 to 7.

5.

5. The water-based metallic paint according to claim 1, wherein in step (3), the temperature of the temperature-raising reaction is 65-75°C, the reaction time is 30-60 minutes, and the heat-insulating reaction time is 60-90 minutes.

6. The water-based metallic paint according to claim 1, wherein in step (4), the time for sufficient reaction is 90 to 120 minutes.

7. The water-based metallic paint according to claim 1, wherein the emulsifier is preferably at least one of allyloxy fatty alcohol oxyethylene ether sulfate, dodecylbenzene sulfonate, alkylphenol polyoxyethylene ether sulfate, and nonylphenol ethoxylate.

8. The water-based metallic paint according to claim 1, wherein the initiator is ammonium persulfate, sodium persulfate or potassium persulfate; and the filler is aluminum powder, copper powder or pearlescent pigment.

9. The water-based metallic paint according to claim 1, wherein in step (4), the time for sufficient reaction is 60 to 90 minutes.

10. A method for preparing a water-based metallic paint according to any one of claims 1 to 9, comprising the following steps: The raw materials are mixed to obtain the water-based metallic paint.

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