Environment-friendly water-based finish paint for metal coiled materials and preparation method thereof

Abstract

The invention provides an environment-friendly water-based finish paint for a metal coiled material and a preparation method thereof, and the environment-friendly water-based finish paint for the metal coiled material comprises the following components in parts by weight: 30-40 parts of water-based polyester resin; 8 to 10 parts of a thickening agent; 1 to 3 parts of DMEA; 5 to 8 parts of amino resin; 3 to 6 parts of BCS; 3 to 6 parts of epoxy phosphate ester; 0.5 to 1 part of a silane coupling agent; 0.5 to 1.0 part of an acid catalyst; 0.1 to 0.2 part of a leveling agent; 0.1 to 0.5 part of a defoaming agent A; 30 to 40 parts of color paste; and the balance of water. The environment-friendly water-based finishing paint for the metal coiled material, provided by the invention, adopts the water-based polyester resin and the titanium dioxide as main raw materials, is low in cost, economical and practical, is water-based paint, and is ultralow in VOC (Volatile Organic Compounds), small in environmental pollution, environment-friendly and excellent in performance. The surface of the metal coiled material applying the environment-friendly water-based finishing paint for the metal coiled material is smooth and free of shrinkage cavities or recesses; the T-bend can reach 0T, the flexibility is good, the butanone resistance is good, the impact resistance is good, the adhesive force is good, and the scratch resistance is good.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to an environmentally friendly water-based topcoat for metal coils and a preparation method thereof. Background Art

[0002] Coil coatings include steel coil coatings and aluminum coil coatings. They are made by coating the surface of steel plates and aluminum plates with a roller coating method, and then made into pre-coated coils. They have the advantages of beautiful appearance, bright colors, high strength, convenient processing and molding, and can also reduce costs and pollution, so they are widely used. Coil coatings are composed of base materials, cross-linking agents, pigments, fillers, additives and volatile components. According to their uses, they can be divided into primers, back paints and topcoats. Generally, aluminum only needs a single coating, while galvanized steel and cold-rolled steel require primers and topcoats.

[0003] At present, solvent-based coil coatings still dominate coil coatings. However, solvent-based coil coatings contain a large amount of organic solvents, and their volatilization causes environmental pollution. In order to solve this problem, water-based coil coatings came into being. However, the technical defects of existing water-based coil topcoats are mainly:

[0004] 1. Shrinkage: the coating will shrink and expose the bottom, forming small circular depressions in the paint film;

[0005] 2. After the coating is cured, there will be uneven lines and marks on the surface of the paint film;

[0006] 3. Poor flexibility;

[0007] 4. Poor butanone resistance;

[0008] 5. The paint film has poor impact resistance and insufficient adhesion;

[0009] 6. The paint film has poor scratch resistance;

[0010] 7. Products with excellent performance have higher usage costs. Summary of the invention

[0011] The object of the present invention is to provide an environmentally friendly water-based topcoat for metal coils and a preparation method thereof, which can at least solve one of the above problems.

[0012] According to one aspect of the present invention, there is provided an environmentally friendly water-based topcoat for metal coils, comprising the following components in parts by weight:

[0013] Water-based polyester resin, 30-40 parts;

[0014] Thickener, 8-10 parts;

[0015] DMEA, 1-3 parts;

[0016] Amino resin, 5-8 parts;

[0017] BCS, 3-6 copies;

[0018] Epoxy phosphate: 3-6 parts;

[0019] Silane coupling agent: 0.5-1 part;

[0020] Acid catalyst: 0.5-1.0 part;

[0021] Leveling agent: 0.1-0.2 parts;

[0022] Defoamer A: 0.1-0.5 parts

[0023] Color paste: 30-40 parts;

[0024] The balance is water.

[0025] In some embodiments, the water-based polyester resin is 35.0 parts, the thickener is 8.2 parts, the DMEA is 1.80 parts, the amino resin is 6.56 parts, the BCS is 5.0 parts, the epoxy phosphate is 3.0 parts, the silane coupling agent is 0.50 parts, the acid catalyst is 0.50 parts, the leveling agent is 0.10 parts, the defoamer A is 0.20 parts, and the color paste is 35.0 parts.

[0026] In some embodiments, the color paste is 70% titanium white paste.

[0027] In some embodiments, the color paste includes the following components in parts by weight:

[0028] BCS, 3-6 copies;

[0029] Defoaming agent B, 0.1-0.5 parts;

[0030] Dispersant, 1 to 3 parts;

[0031] Titanium dioxide, 70 parts;

[0032] DMEA, 0.1-0.5 parts;

[0033] The balance is water.

[0034] In some embodiments, BCS is 5 parts, defoamer B is 0.20 parts, dispersant is 2.10 parts, titanium dioxide is 70 parts, and DMEA is 0.20 parts.

[0035] In some embodiments, the water is deionized water.

[0036] According to one aspect of the present invention, there is also provided a method for preparing an environmentally friendly water-based topcoat for a metal coil, characterized in that it comprises at least the following steps:

[0037] S1. Prepare color paste: put water, BCS, defoamer B, dispersant, titanium dioxide and DMEA into a stirring device in order, adjust the speed of the stirring device to 1000r / min, stir for 30min, and then grind to a fineness of less than or equal to 15μm to obtain a color paste for standby use;

[0038] S2, paint preparation: put water-based polyester resin, thickener, DMEA, amino resin, BCS, epoxy phosphate, silane coupling agent, acid catalyst, leveling agent, defoamer A and the color paste prepared in step S1 into a stirring device in order, stir evenly, adjust the viscosity to 2# Iwata cup 60s with water, and obtain an environmentally friendly water-based topcoat for metal coils.

[0039] In some embodiments, in step S2, the viscosity can also be adjusted to 2# Iwata cup 40s with water to obtain an environmentally friendly water-based topcoat for metal coils that can be used for direct construction.

[0040] In some embodiments, in step S2, water-based polyester resin, thickener, DMEA, amino resin, BCS, and epoxy phosphate are first added to a stirring device, the speed of the stirring device is controlled at 1500 r / min, and the stirring time is controlled to be more than 15 min. Then, the speed of the stirring device is controlled at 500 r / min, and a silane coupling agent, an acid catalyst, a leveling agent, a defoaming agent A, and the color paste prepared in step S1 are added to the stirring device in sequence while stirring, and the stirring time is controlled to be more than 25 min.

[0041] Beneficial effects of the present invention:

[0042] The present invention provides an environmentally friendly water-based topcoat for metal coils, which uses water-based polyester resin and titanium dioxide as main raw materials, has low cost and is economical;

[0043] This environmentally friendly water-based topcoat for metal coils is a water-based paint with ultra-low VOC, low environmental pollution and environmental protection;

[0044] After testing, the environmentally friendly water-based topcoat used for the metal coil has a smooth surface without shrinkage cavities or depressions; the T-bend can reach 0T and has good flexibility; the butanone resistance can reach up to 120 times without loss of gloss or discoloration, and the butanone resistance performance is good; the paint film has good impact resistance; the adhesion can reach level 0, and the adhesion is good; the paint film has good scratch resistance; more importantly, the raw material cost is low, so that the product of the present invention has low use cost but excellent performance. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below.

[0046] The environmentally friendly water-based topcoat for metal coils of the present invention comprises the following components in parts by weight:

[0047] Water-based polyester resin, 30-40 parts;

[0048] Thickener, 8-10 parts;

[0049] DMEA, 1-3 parts;

[0050] Amino resin, 5-8 parts;

[0051] BCS, 3-6 copies;

[0052] Epoxy phosphate: 3-6 parts;

[0053] Silane coupling agent: 0.5-1 part;

[0054] Acid catalyst: 0.5-1.0 part;

[0055] Leveling agent: 0.1-0.2 parts;

[0056] Defoamer A: 0.1-0.5 parts

[0057] Color paste: 30-40 parts;

[0058] The balance is water.

[0059] Preferably, the water-based polyester resin is 35.0 parts, the thickener is 8.2 parts, the DMEA is 1.80 parts, the amino resin is 6.56 parts, the BCS is 5.0 parts, the epoxy phosphate is 3.0 parts, the silane coupling agent is 0.50 parts, the acid catalyst is 0.50 parts, the leveling agent is 0.10 parts, the defoamer A is 0.20 parts, and the color paste is 35.0 parts.

[0060] Preferably, the color paste is 70% titanium dioxide paste.

[0061] Preferably, the color paste comprises the following components in parts by weight:

[0062] BCS, 3-6 copies;

[0063] Defoaming agent B, 0.1-0.5 parts;

[0064] Dispersant, 1 to 3 parts;

[0065] Titanium dioxide, 70 parts;

[0066] DMEA, 0.1-0.5 parts;

[0067] The balance is water.

[0068] Preferably, BCS is 5 parts, defoamer B is 0.20 parts, dispersant is 2.10 parts, titanium dioxide is 70 parts, and DMEA is 0.20 parts.

[0069] Preferably, the water is deionized water.

[0070] The water-based polyester resin was a commercially available product purchased from Xuzhou Xuanchen Environmental Protection Technology Co., Ltd.

[0071] Thickener is made from German Mingling Chemical PUR-603 thickener;

[0072] DMEA is N, N-dimethylethanolamine, and the manufacturer is Nanjing Qunce Chemical Co., Ltd.;

[0073] The amino resin is purchased from Taiwan Chang Chun Chemical (Chang Chun Group) MR-625 amino resin, which is a methyl etherified amino resin. In the present invention, it is compounded with epoxy phosphate to improve the butanone resistance of the topcoat;

[0074] BCS is ethylene glycol monobutyl ether, which can dissolve polyester resin, amino resin, etc. as a solvent;

[0075] Epoxy phosphate was purchased from Changxing Chemical's 4901-B-72 epoxy phosphate, which is a functional additive mainly used to improve the adhesion, chemical resistance and mechanical properties of materials such as coatings and adhesives. The epoxy phosphate of the present invention is used as an adhesion promoter to enhance the bonding between the coating and the metal substrate; MR-625 amino resin is used as a cross-linking agent to improve the solvent resistance and hardness of the paint film through high cross-linking density. The two can synergistically significantly improve the durability of the coating in a corrosive environment.

[0076] The silane coupling agent used is Momentive's MP-200 silane coupling agent, which is an adhesion promoter specially designed for water-based systems. It is mainly used to enhance the adhesion between water-based polyester resins, water-based amino resins and metal substrates. The silane coupling agent can improve adhesion, and when combined with MR-625 amino resin, it can increase the crosslinking density, enhance solvent resistance and hardness, and when combined with epoxy phosphate, it has a dual effect of strengthening the adhesion of metal substrates.

[0077] The acid catalyst used is NACURE-2500 produced by King Industries of the United States, which is a closed acid catalyst whose main component is p-toluenesulfonic acid (p-TSA). It is used in combination with water-based polyester resin to accelerate the cross-linking reaction and improve the hardness, gloss and chemical resistance of the coating.

[0078] The leveling agent used is BYK-333 produced by BYK of Germany, which is a high-performance silicone leveling agent used to improve surface leveling, wettability and anti-cratering performance. It can improve surface flatness, wettability and smoothness, and solve problems such as craters and orange peel.

[0079] Both defoamer A and defoamer B can be BYK-024 defoamer produced by BYK of Germany.

[0080] The dispersant used is Tego Dispers 750W produced by Germany's Tego, which is a high-performance water-based wetting dispersant. It is mainly used to improve the dispersion stability and coloring effect of pigments in coatings, inks and other systems, and has an outstanding stabilizing effect on titanium dioxide.

[0081] The titanium dioxide used is Longbai / Longmang R-996 titanium dioxide.

[0082] The present invention provides an environmentally friendly water-based topcoat for metal coils, which uses water-based polyester resin and titanium dioxide as main raw materials, has low cost and is economical;

[0083] This environmentally friendly water-based topcoat for metal coils is a water-based paint with ultra-low VOC, low environmental pollution and environmental protection;

[0084] After testing, the environmentally friendly water-based topcoat used for the metal coil has a smooth surface without shrinkage cavities or depressions; the T-bend can reach 0T and has good flexibility; the butanone resistance can reach up to 120 times without loss of gloss or discoloration, and the butanone resistance performance is good; the paint film has good impact resistance; the adhesion can reach level 0, and the adhesion is good; the paint film has good scratch resistance; more importantly, the raw material cost is low, so that the product of the present invention has low use cost but excellent performance.

[0085] The present invention also discloses a method for preparing the environmentally friendly water-based topcoat for metal coils, which at least comprises the following steps:

[0086] S1. Prepare color paste: put water, BCS, defoamer B, dispersant, titanium dioxide and DMEA into a stirring device in order, adjust the speed of the stirring device to 1000r / min, stir for 30min, and then grind to a fineness of less than or equal to 15μm to obtain a color paste for standby use;

[0087] S2, paint preparation: put water-based polyester resin, thickener, DMEA, amino resin, BCS, epoxy phosphate, silane coupling agent, acid catalyst, leveling agent, defoamer A and the color paste prepared in step S1 into a stirring device in order, stir evenly, adjust the viscosity to 2# Iwata cup 60s with water, and obtain an environmentally friendly water-based topcoat for metal coils, which is set aside.

[0088] Specifically, in step S2, first put water-based polyester resin, thickener, DMEA, amino resin, BCS, and epoxy phosphate into a stirring device, control the speed of the stirring device at 1500 r / min, and control the stirring time to more than 15 min. Then, control the speed of the stirring device at 500 r / min, and add silane coupling agent, acid catalyst, leveling agent, defoaming agent A, and the color paste prepared in step S1 into the stirring device in sequence while stirring, and control the stirring time to more than 25 min.

[0089] In addition, if it is prepared and used immediately, in step S2, the viscosity is directly adjusted to 2# Iwata cup with water for 40 seconds and then the application can be carried out directly.

[0090] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0091] Example 1

[0092] This embodiment provides an environmentally friendly water-based topcoat for metal coils. The specific components and proportions of the environmentally friendly water-based topcoat for metal coils are shown in Table 1 below:

[0093] Table 1: Proportion table of environmentally friendly water-based topcoat for metal coils of Example 1

[0094] Components Weight Waterborne polyester resin 35 Thickener 8.2 DMEA 1.8 Amino resin 6.56 BCS 5 Epoxy Phosphate 3 Silane coupling agent 0.5 Acid Catalyst 0.5 Leveling agent 0.1 Defoamer A 0.2 Color paste 35 Deionized water 4.14

[0095] The specific components and proportions of the color paste in the environmentally friendly water-based topcoat for metal coils are shown in Table 2 below:

[0096] Table 2: Proportion table of the color paste of Example 1

[0097] Components Weight BCS 5 Dispersants 2.1 Defoamer B 0.2 Titanium dioxide 70 DMEA 0.2 Deionized water 22.5

[0098] According to the ratio table in Table 1-2 above, the environmentally friendly water-based topcoat for metal coil is prepared by the following preparation method, which specifically includes the following steps:

[0099] S1. Prepare color paste: put 22.5 parts of deionized water, 5 parts of BCS, 0.2 parts of defoamer B, 2.1 parts of dispersant, 70 parts of titanium dioxide, and 0.2 parts of DMEA into a stirring device in order, adjust the speed of the stirring device to 1000r / min, stir for 30 minutes, and then grind to a fineness of less than or equal to 15μm to obtain a color paste for standby use;

[0100] S2, paint preparation: first, 35 parts of water-based polyester resin, 8.2 parts of thickener, 1.8 parts of DMEA, 6.56 parts of amino resin, 5 parts of BCS, and 3 parts of epoxy phosphate are sequentially added into a stirring device, the speed of the stirring device is controlled at 1500 r / min, and the stirring time is controlled at more than 15 min, and then the speed of the stirring device is controlled at 500 r / min, 0.5 parts of silane coupling agent, 0.5 parts of acid catalyst, 0.1 parts of leveling agent, 0.2 parts of defoamer A and 35 parts of the color paste prepared in step S1 are sequentially added into the stirring device while stirring, the stirring time is controlled at more than 25 min, and after stirring evenly, the viscosity is adjusted to 2# Iwata cup 60s with water to obtain an environmentally friendly water-based topcoat for metal coils.

[0101] Example 2

[0102] This embodiment provides another environmentally friendly water-based topcoat for metal coils. The specific components and proportions of the environmentally friendly water-based topcoat for metal coils are shown in Table 3 below:

[0103] Table 3: Proportion table of environmentally friendly water-based topcoat for metal coils of Example 2

[0104] Components Weight Waterborne polyester resin 35 Thickener 8.2 DMEA 1.8 Amino resin 6.6 BCS 5 Epoxy Phosphate 3 Silane coupling agent 0.5 Acid Catalyst 0.5 Leveling agent 0.1 Defoamer A 0.2 Color paste 35 Deionized water 4.1

[0105] The specific components and proportions of the color paste in the environmentally friendly water-based topcoat for metal coils are shown in Table 4 below:

[0106] Table 4: Proportion table of the color paste of Example 2

[0107] Components Weight BCS 5 Dispersants 2.1 Defoamer B 0.2 Titanium dioxide 70 DMEA 0.2 Deionized water 22.5

[0108] According to the ratio tables in Table 3 and Table 4, the environmentally friendly water-based topcoat for metal coils of this embodiment is prepared by the same preparation method as that of Example 1.

[0109] Example 3

[0110] This embodiment provides another environmentally friendly water-based topcoat for metal coils. The specific components and proportions of the environmentally friendly water-based topcoat for metal coils are shown in Table 5 below:

[0111] Table 5: Proportion table of environmentally friendly water-based topcoat for metal coils of Example 3

[0112] Components Weight Waterborne polyester resin 35 Thickener 8.2 DMEA 1.8 Amino resin 6 BCS 5 Epoxy Phosphate 3 Silane coupling agent 0.5 Acid Catalyst 0.5 Leveling agent 0.1 Defoamer A 0.2 Color paste 35 Deionized water 4.7

[0113] The specific components and proportions of the color paste in the environmentally friendly water-based topcoat for metal coils are shown in Table 6 below:

[0114] Table 6: Proportion table of the color paste of Example 3

[0115] Components Weight BCS 5 Dispersants 1.1 Defoamer B 0.2 Titanium dioxide 70 DMEA 0.2 Deionized water 21.5

[0116] According to the ratio tables in Table 5 and Table 6, the environmentally friendly water-based topcoat for metal coils of this embodiment is prepared by the same preparation method as that of Example 1.

[0117] Example 4

[0118] This embodiment provides another environmentally friendly water-based topcoat for metal coils. The specific components and proportions of the environmentally friendly water-based topcoat for metal coils are shown in Table 7 below:

[0119] Table 7: Proportion table of environmentally friendly water-based topcoat for metal coils of Example 4

[0120] Components Weight Waterborne polyester resin 35 Thickener 8 DMEA 1.5 Amino resin 6.6 BCS 5 Epoxy Phosphate 3 Silane coupling agent 0.5 Acid Catalyst 0.5 Leveling agent 0.1 Defoamer A 0.2 Color paste 35 Deionized water 4.6

[0121] The specific components and proportions of the color paste in the environmentally friendly water-based topcoat for metal coils are shown in Table 8 below:

[0122] Table 8: Proportion table of the color paste of Example 4

[0123] Components Weight BCS 5 Dispersants 1.5 Defoamer B 0.2 Titanium dioxide 70 DMEA 0.2 Deionized water 23.1

[0124] According to the ratio tables in Table 7 and Table 8, the environmentally friendly water-based topcoat for metal coils of this embodiment is prepared by the same preparation method as that of Example 1.

[0125] Example 5

[0126] The environmentally friendly water-based topcoat for metal coils prepared in the above-mentioned embodiments 1-4 is coated on the test substrate according to the above-mentioned application method, baked at 250°C for 90s, with a plate temperature of 220°C, and then subjected to a performance test. The substrate material is aluminum or carbon steel. The performance of the environmentally friendly water-based topcoat for metal coils prepared in the above-mentioned embodiments 1-4 is tested using the known national standard method. Specifically, the test items include hardness, salt spray resistance, boiling water resistance, water resistance, weather resistance, butanone resistance, etc. The performance test results of the environmentally friendly water-based topcoat for metal coils obtained in the embodiments 1-4 are shown in Table 9 below:

[0127] Table 9: Performance test table of environmentally friendly water-based topcoats for metal coils of Examples 1-4

[0128]

[0129] According to the data in Table 9, the environmentally friendly water-based topcoat for metal coils of the present invention not only has the characteristics of low cost and environmental protection, but also has excellent properties such as water resistance, weather resistance, impact resistance, adhesion, and butanone resistance. The T-bend can also achieve 0T without cracks, and is very suitable for the surface treatment of metal coils.

[0130] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. An environmentally friendly water-based topcoat for metal coils, characterized in that: The composition comprises the following components in parts by weight: Water-based polyester resin, 30-40 parts; Thickener, 8-10 parts; DMEA, 1-3 parts; Amino resin, 5-8 parts; BCS, 3-6 copies; Epoxy phosphate: 3-6 parts; Silane coupling agent: 0.5-1 part; Acid catalyst: 0.5-1.0 part; Leveling agent: 0.1-0.2 parts; Defoamer A: 0.1-0.5 parts Color paste: 30-40 parts; The balance is water.

2. The environmentally friendly water-based topcoat for metal coil according to claim 1, characterized in that: The water-based polyester resin is 35.0 parts, the thickener is 8.2 parts, the DMEA is 1.80 parts, the amino resin is 6.56 parts, the BCS is 5.0 parts, the epoxy phosphate is 3.0 parts, the silane coupling agent is 0.50 parts, the acid catalyst is 0.50 parts, the leveling agent is 0.10 parts, the defoamer A is 0.20 parts, and the color paste is 35.0 parts.

3. The environmentally friendly water-based topcoat for metal coil according to claim 1, characterized in that: The color paste is 70% titanium dioxide paste.

4. The environmentally friendly water-based topcoat for metal coil according to claim 3, characterized in that: The color paste includes the following components by weight: BCS, 3-6 copies; Defoaming agent B, 0.1-0.5 parts; Dispersant, 1 to 3 parts; Titanium dioxide, 70 parts; DMEA, 0.1-0.5 parts; The balance is water.

5. The environmentally friendly water-based topcoat for metal coil according to claim 4, characterized in that: The BCS is 5 parts, the defoamer B is 0.20 parts, the dispersant is 2.10 parts, the titanium dioxide is 70 parts, and the DMEA is 0.20 parts.

6. The environmentally friendly water-based topcoat for metal coil according to claim 1 or 4, characterized in that: The water is deionized water.

7. A method for preparing an environmentally friendly water-based topcoat for metal coils, characterized in that: At least the following steps are included: S1. Prepare color paste: put water, BCS, defoamer B, dispersant, titanium dioxide and DMEA into a stirring device in order, adjust the speed of the stirring device to 1000r / min, stir for 30min, and then grind to a fineness of less than or equal to 15μm to obtain a color paste for standby use; S2, paint preparation: put water-based polyester resin, thickener, DMEA, amino resin, BCS, epoxy phosphate, silane coupling agent, acid catalyst, leveling agent, defoamer A and the color paste prepared in step S1 into a stirring device in order, stir evenly, adjust the viscosity to 2# Iwata cup 60s with water, and obtain an environmentally friendly water-based topcoat for metal coils.

8. The method for preparing an environmentally friendly water-based topcoat for metal coil according to claim 7, characterized in that: In step S2, the viscosity can also be adjusted to 2# Iwata cup 40s with water to obtain an environmentally friendly water-based topcoat for metal coils that can be used for direct construction.

9. The method for preparing an environmentally friendly water-based topcoat for metal coil according to claim 7, characterized in that: In step S2, water-based polyester resin, thickener, DMEA, amino resin, BCS, and epoxy phosphate are first added to a stirring device, the speed of the stirring device is controlled at 1500 r / min, and the stirring time is controlled to be more than 15 min. Then, the speed of the stirring device is controlled at 500 r / min, and a silane coupling agent, an acid catalyst, a leveling agent, a defoaming agent A, and the color paste prepared in step S1 are added to the stirring device in sequence while stirring, and the stirring time is controlled to be more than 25 min.

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