Alkali-resistant animal husbandry color-coated plate and manufacturing method thereof

Abstract

The present invention belongs to the technical field of color-coated steel sheets, and specifically relates to an alkali-resistant livestock color-coated sheet and a manufacturing method thereof. The color-coated sheet comprises a color-coated substrate, a passivation layer, a front coating, and a back coating. The coating of the color-coated substrate is a hot-dip galvanized aluminum-magnesium coating containing 30-79% Al, 0.1-5% Si, 1.2-2.0% Mg, and the remainder being Zn and unavoidable impurities; the coating weight is 60-250g / m 2 The passivation layer is a chromate passivation layer with a single-side weight of 15-35 mg / m 2 The primer resin contains 10-15% epoxy resin E-03, 30-35% epoxy resin E-20, and 20-25% blocked isocyanate; the topcoat resin contains 30-35% polyester resin, 25-30% high methyl etherified imino resin, and 0.8-2.0% methyl etherified benzoguanamine resin. This invention improves the alkali resistance and C4 corrosion resistance of livestock color-coated panels.

Description

Technical Field

[0001] The invention belongs to the technical field of color-coated steel plates, and in particular relates to an alkali-resistant animal husbandry color-coated plate and a manufacturing method thereof. Background Art

[0002] Livestock-specific coated steel plate is a new type of color-coated steel plate, primarily used in modern farms, feed processing plants, slaughterhouses, and other fields. Due to the unique application environment of livestock farms, livestock-specific coated steel plate must possess excellent corrosion and chemical resistance. For example, in cattle farms, excrement such as cow dung is generally alkaline, and sodium hydroxide-based alkaline disinfectants are often used for environmental disinfection. As a result, the cattle-raising environment is typically highly oxidizing and corrosive. This requires that livestock-specific color-coated steel plate be able to effectively resist these corrosive factors during long-term use, ensuring that the surface coating does not blister, peel, or rust, thereby ensuring the safety and stability of the building panels in livestock farms.

[0003] Currently, the traditional livestock industry primarily uses standard architectural color-coated steel sheets, but their performance indicators fail to meet the actual needs of the livestock industry. In terms of corrosion resistance, the best SST cross-sectional corrosion propagation distance for existing architectural color-coated steel sheets after 250 hours is 3.5mm, and after 500 hours, the SST cross-sectional corrosion propagation distance is over 12mm, far below the requirements for livestock color-coated steel sheets: a corrosion propagation distance of ≤2mm after 250 hours and ≤3mm after 500 hours. In terms of chemical resistance, such as sodium hydroxide resistance, the coating on standard architectural color-coated steel sheets typically begins to blister or flake after 48 hours, while the chemical resistance required for livestock color-coated steel sheets is greater than 300 hours, resulting in a significant performance gap. These issues seriously impact the service life of livestock pens and the stability of breeding facilities. Therefore, to meet the development needs of modern livestock farming, it is crucial to research and develop specialized color-coated steel sheets that possess both excellent corrosion resistance and superior chemical resistance. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides an alkali-resistant animal husbandry color-coated plate and a manufacturing method thereof for the alkaline environment of cattle breeding sites, so as to meet the requirements of use in the alkaline environment of cattle breeding.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0006] The present invention provides an alkali-resistant animal husbandry color-coated steel plate, comprising a color-coated substrate, a passivation layer, a front coating, and a back coating. The front coating is composed of a primer combined with a topcoat layer, and the back coating is composed of a single primer layer or a primer layer combined with a topcoat layer. The invention is characterized in that the coating of the color-coated substrate is a hot-dip aluminum-zinc-magnesium coating, which, in terms of mass percentage, comprises 30%-79% Al, 0.1%-5% Si, 1.2%-2.0% Mg, and the remainder being Zn and unavoidable impurities; the coating weighs 60 g / m 2 -250g / m 2 ;

[0007] The passivation layer is a chromate passivation layer with a single-side weight of 15 mg / m 2 -35 mg / m 2 ;

[0008] The primer of the front coating or back coating includes a primer resin, a diluent, and a pigment and filler. The primer resin includes epoxy resin E-03, epoxy resin E-20, and blocked isocyanate. In terms of mass percentage, the epoxy resin E-03 is 10%-15%, the epoxy resin E-20 is 30%-35%, the blocked isocyanate is 20%-25%, and the rest is the diluent and pigment and filler.

[0009] The topcoat of the front coating or the back coating includes a topcoat resin, a diluent and pigments and fillers. The topcoat resin includes a polyester resin, a high-methylated imino resin and a methylated benzoguanamine resin. In terms of mass percentage, the polyester resin is 30%-35%, the high-methylated imino resin is 25%-30%, the methylated benzoguanamine resin is 0.8%-2.0%, and the balance is the diluent and pigments and fillers.

[0010] In the above technical solution, further, the coating weight is 100 g / m 2 -150g / m 2 .

[0011] In the above technical solution, further, the components of the chromate passivation layer include Na2CrO4 and water-based silicone resin.

[0012] In the above technical solution, further, the preparation process of the alkali-resistant animal husbandry color coated steel plate includes: pre-treatment of the color-coated substrate, passivation, primer and topcoat coating and baking;

[0013] In the primer and topcoat coating process, the particle size of the pigment and filler of the primer is 1 μm-1.5 μm; the particle size of the pigment and filler of the topcoat is 1 μm-2 μm.

[0014] In the above technical solution, further, the thickness of the primer film is 5μm-6μm, the thickness of the topcoat film is 18μm-25μm; the viscosity of the primer is 50s-70s, and the viscosity of the topcoat is 60s-80s.

[0015] In the above technical solution, further, in the passivation process, a water-based chromic acid liquid compound is coated on the surface of the color-coated substrate, the drying temperature is 170°C-190°C, and the temperature is cooled to below 40°C.

[0016] In the above technical solution, further, in the baking process, the baking temperature is 216°C-232°C.

[0017] The present invention also provides the use of the alkali-resistant animal husbandry color-coated steel plate as a building panel material for cattle farms.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention adopts a high-aluminum-zinc-magnesium coating substrate and a specific magnesium content range, so that the color-coated plate forms a dense protective film (white rust) composed of aluminum zinc hydroxide, alkaline aluminum zinc chloride and magnesium hydroxide during the corrosion process, gradually covering the exposed incision metal, separating the external corrosive medium from the exposed metal substrate, thereby preventing further corrosion of the exposed incision; and on this basis, by selecting an epoxy modified primer and a high-density polyester topcoat, the corrosion resistance and chemical resistance of the color-coated plate coating are significantly improved; the above-mentioned two are tightly combined through a passivation layer of a specific thickness (weight), thereby maximizing the alkali resistance and C4 corrosion environment of the livestock color-coated plate.

[0020] The color-coated plate of the present invention meets the requirement of ≤3mm in SST corrosion spreading distance after 500 hours, and has no blistering or falling off after 400 hours under alkaline conditions such as 10% NaOH and no change or blistering after 400 hours under 10% sodium hypochlorite. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to specific examples, but the present invention is not limited thereto in any way.

[0022] The preparation process of the color-coated steel plate in the following embodiment includes the following steps:

[0023] (1) Pretreatment: Hot-dip galvanized aluminum-magnesium steel sheet is used as the substrate, wherein Al70%, Si3.5%, Mg1.0%-2.0%, and the rest are Zn and inevitable impurities. The strip is fed through the uncoiler and sent to the pretreatment section through the tensioner. The surface of the strip is pretreated to improve the adhesion of the plate surface. The surface pretreatment is degreasing and cleaning;

[0024] (2) Passivation: After pretreatment, the strip enters the chemical coating machine, where a layer of water-based chromate passivation solution (containing Na2CrO4 and water-based silicone resin, the passivation solution is purchased directly from commercial sources) is coated on the surface of the strip. After exiting the chemical coating machine, the strip enters the drying furnace for drying at 180°C, and the strip is cooled to below 40°C.

[0025] (3) Paint coating: After passivation, the strip is primed on the front side. The grinding particle size of the pigment filler of the primer is controlled at 1.5 microns, and the paint film thickness is 6 microns. The grinding particle size of the pigment filler of the front side topcoat is controlled at 2 microns, and the paint film thickness is 20 microns. The back side is coated with epoxy primer, and the paint film thickness is 6 microns. The second coating is consistent with the front side topcoat. The diluent used in the primer or topcoat can be a conventional diluent such as methylbenzene or isophorone to control the viscosity of the primer to 60s and the viscosity of the topcoat to 70s.

[0026] (4) Baking: The baking plate temperature is controlled at 232°C. The strip steel after being taken out of the oven enters the water quenching tank for cooling and then is dried. Finally, the strip steel passes through the inspection table and the exit shear, and is cut into the required coil weight to obtain the alkali-resistant color plate specially used for animal husbandry.

[0027] The polyester resin used in the following examples is 385 saturated polyester resin. Epoxy resin E-03, epoxy resin E-20, blocked isocyanate, high-methylated imino resin, methylated phenylguanamine resin, and 385 saturated polyester resin are all commercially available. The following examples all utilize the above-described preparation process to produce color-coated steel sheets with varying coating magnesium content, coating weights, passivation layer weights per side, and ratios of primer resin to topcoat resin, and their performance is tested.

[0028] Example 1

[0029] The coating has a magnesium content of 1.2% and a weight of 120g / m 2 ; Passivation layer single side weight 15mg / m 2 The mass percentages of primer resins E-03, E-20 and blocked isocyanate are 15%, 35% and 20% respectively; the mass percentages of topcoat resin polyester resin plus high methyl etherified imino resin and methyl etherified benzoguanamine resin are 30%, 25% and 1.0% respectively.

[0030] Example 2

[0031] The coating has a magnesium content of 1.5% and a weight of 120g / m 2 ; Passivation layer single side weight 25mg / m 2The mass percentages of primer resins E-03, E-20 and blocked isocyanate are 12%, 35% and 20% respectively; the mass percentages of topcoat resin polyester resin plus high methyl etherified imino resin and methyl etherified benzoguanamine resin are 33%, 25% and 1.2% respectively.

[0032] Example 3

[0033] The coating has a magnesium content of 2.0% and a weight of 150g / m 2 ; Passivation layer single side weight 15mg / m 2 The mass percentages of primer resins E-03, E-20 and blocked isocyanate are 10%, 30% and 23% respectively; the mass percentages of topcoat resin polyester resin plus high methyl etherified imino resin and methyl etherified benzoguanamine resin are 35%, 25% and 0.8% respectively.

[0034] Example 4

[0035] The coating has a magnesium content of 1.8% and a weight of 150g / m 2 ; Passivation layer single side weight 30mg / m 2 The mass percentages of primer resins E-03, E-20 and blocked isocyanate are 13%, 30% and 20% respectively; the mass percentages of topcoat resin polyester resin plus high methyl etherified imino resin and methyl etherified benzoguanamine resin are 30%, 30% and 2.0% respectively.

[0036] Example 5

[0037] The coating has a magnesium content of 1.6% and a weight of 150g / m 2 ; Passivation layer single side weight 30mg / m 2 The mass percentages of primer resins E-03, E-20 and blocked isocyanate are 15%, 30% and 25% respectively; the mass percentages of topcoat resin polyester resin plus high methyl etherified imino resin and methyl etherified benzoguanamine resin are 35%, 25% and 1.8% respectively.

[0038] Comparative Example 1

[0039] The coating has a magnesium content of 2.4% and a weight of 150g / m 2 ; Passivation film weight 30mg / m 2 The mass percentages of primer resins E-03, E-20 and blocked isocyanate are 15%, 30% and 25% respectively; the mass percentages of topcoat resin polyester resin plus high methyl etherified imino resin and methyl etherified benzoguanamine resin are 35%, 25% and 1.8% respectively.

[0040] Comparative Example 2

[0041] The coating has a magnesium content of 1.0% and a weight of 150g / m 2 ; Passivation film weight 12mg / m 2 The mass percentages of primer resins E-03, E-20 and blocked isocyanate are 15%, 30% and 20% respectively; the mass percentages of topcoat resin polyester resin plus high methyl etherified imino resin and methyl etherified benzoguanamine resin are 35%, 25% and 1.8% respectively.

[0042] Comparative Example 3

[0043] The coating has a magnesium content of 1.6% and a weight of 150g / m 2 ; Passivation film weight 12mg / m 2 The mass percentages of primer resins E-03, E-20 and blocked isocyanate are 15%, 30% and 20% respectively; the mass percentages of topcoat resin polyester resin plus high methyl etherified imino resin and methyl etherified benzoguanamine resin are 35%, 25% and 1.8% respectively.

[0044] Comparative Example 4

[0045] The coating has a magnesium content of 1.0% and a weight of 150g / m 2 ; Passivation film weight 30mg / m 2 The mass percentages of primer resins E-03, E-20 and blocked isocyanate are 15%, 30% and 20% respectively; the mass percentages of topcoat resin polyester resin plus high methyl etherified imino resin and methyl etherified benzoguanamine resin are 35%, 25% and 1.8% respectively.

[0046] Comparative Example 5

[0047] The coating has a magnesium content of 1.6% and a weight of 150g / m 2 ; Passivation film weight 30mg / m 2 The mass percentages of primer resins E-03, E-20 and blocked isocyanate are 15%, 30% and 20% respectively; the mass percentages of topcoat resin polyester resin plus high methyl etherified imino resin and methyl etherified benzoguanamine resin are 35%, 35% and 2.2% respectively.

[0048] The performance of the above examples and comparative examples are shown in Table 1.

[0049] Table 1

[0050]

[0051] The color-coated sheet prepared using Example 5 exhibited the best impact, T-bend, salt spray corrosion resistance, and chemical resistance. However, the increased magnesium content in the coating in Comparative Example 1 did not significantly improve corrosion resistance, while the reduced magnesium content and passivation layer weight in Comparative Example 2 significantly impacted the corrosion resistance of the color-coated sheet. In Comparative Example 5, the coating's toughness decreased, resulting in cracks and paint peeling during bending, resulting in poor overall performance.

[0052] Anyone skilled in the art will be able to utilize the above-disclosed technical content to make many possible changes and modifications to the technical solution of the present invention, or to modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention that do not depart from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. An alkali-resistant color-coated plate for animal husbandry, comprising a color-coated substrate, a passivation layer, a front coating, and a back coating, wherein the front coating is composed of a primer combined with a topcoat layer, and the back coating is a single primer layer or a primer layer combined with a topcoat layer, characterized in that: The coating of the color-coated substrate is a hot-dip aluminum-zinc-magnesium coating, which, by mass percentage, comprises 30%-79% Al, 0.1%-5% Si, 1.6%-2.0% Mg, and the remainder is Zn and unavoidable impurities; the coating weight is 60 g / m 2 -250g / m 2 ; The passivation layer is a chromate passivation layer with a single-side weight of 15 mg / m 2 -35 mg / m 2 ; The primer of the front coating or back coating includes a primer resin, a diluent, and a pigment and filler. The primer resin includes epoxy resin E-03, epoxy resin E-20, and blocked isocyanate. In terms of mass percentage, the epoxy resin E-03 comprises 10%-15%, the epoxy resin E-20 comprises 30%-35%, the blocked isocyanate comprises 20%-25%, and the rest comprises diluent and pigment and filler. The topcoat of the front coating or the back coating includes a topcoat resin, a diluent and pigments and fillers. The topcoat resin includes a polyester resin, a high-methylated imino resin and a methylated benzoguanamine resin. In terms of mass percentage, the polyester resin is 30%-35%, the high-methylated imino resin is 25%-30%, the methylated benzoguanamine resin is 0.8%-1.8%, and the balance is the diluent and pigments and fillers.

2. The alkali-resistant animal husbandry color-coated plate according to claim 1, characterized in that: The components of the chromate passivation layer include Na2CrO4 and water-based silicone resin.

3. The alkali-resistant animal husbandry color-coated plate according to claim 1, characterized in that: The preparation process of the alkali-resistant animal husbandry color-coated plate includes: pre-treatment of the color-coated substrate, passivation, primer and topcoat coating, and baking; In the primer and topcoat coating process, the particle size of the pigment and filler of the primer is 1 μm-1.5 μm; the particle size of the pigment and filler of the topcoat is 1 μm-2 μm.

4. The alkali-resistant animal husbandry color-coated plate according to claim 3, characterized in that: The thickness of the primer film is 5 μm-6 μm, and the thickness of the topcoat film is 18 μm-25 μm; The viscosity of the primer is 50 s-70 s, and the viscosity of the topcoat is 60 s-80 s.

5. The alkali-resistant animal husbandry color-coated plate according to claim 3, characterized in that: In the passivation process, a water-based chromate passivation solution is coated on the surface of the color-coated substrate, dried at a temperature of 170° C. to 190° C., and cooled to below 40° C.

6. The alkali-resistant animal husbandry color-coated plate according to claim 3, characterized in that: In the baking process, the baking temperature is 216°C-232°C.

7. Use of the alkali-resistant animal husbandry color-coated plate according to any one of claims 1 to 6 as a building panel material for cattle farms.

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