UV-coated steel plate having good corrosion resistance and processability, and manufacturing method therefor

Abstract

Disclosed in the present invention is a UV-coated steel plate having good corrosion resistance and processability. The UV-coated steel plate comprises a coated steel plate, and at least one surface of the coated steel plate is provided with a UV coating. The UV coating contains the following active ingredients: 40-55 parts by weight of a composite resin A, wherein the composite resin A comprises an aliphatic polyurethane acrylate oligomer A1 containing 15-25 wt% of an acrylate monomer having an unsaturated double bond, and an amine-modified epoxy diacrylate oligomer A2 containing 25-35 wt% of an acrylate monomer having an unsaturated double bond; 5-12 parts by weight of an organosilicon compound B; 12-22 parts by weight of a monofunctional alkenyl unsaturated polymerizable monomer C; 4-13 parts by weight of an acrylic phosphate compound D; 0.5-3 parts by weight of an acrylic titanium salt or zirconium salt compound E; and 6-10 parts by weight of a UV photoinitiator F. Further disclosed in the present invention are a manufacturing method for the UV-coated steel plate having good corrosion resistance and processability, and a UV coating for a coated steel plate.

Description

A UV-coated steel sheet with good corrosion resistance and processing properties and its manufacturing method Technical Field

[0001] This invention relates to a steel sheet with a surface coating, and more particularly to a UV-coated steel sheet with a surface coating. Background Technology

[0002] Coated steel sheet, also known as pre-coated steel sheet, is a type of steel sheet made by coating one or more layers of organic coating on the surface of a metal substrate (zinc-aluminum-magnesium sheet, aluminum-zinc plate, hot-dip galvanized sheet, cold-rolled sheet) and then curing it.

[0003] The traditional production process for coated steel sheets involves using thermosetting to dry water-based or solvent-based coatings applied to the steel sheet surface into a film. While this traditional thermosetting process is highly mature and produces stable quality, it also has limitations. For example, the production efficiency of coated steel sheets is restricted by the thermosetting speed, and the thermosetting equipment requires a large floor space. These factors limit the production efficiency of traditional coated steel sheets. Furthermore, thermosetting has high energy and operating costs, and the evaporation of solvents leads to VOC (volatile organic compound) problems, impacting the surrounding environment and resulting in high carbon emissions.

[0004] UV curing technology uses an electrically excited light source to generate ultraviolet light. The medium- and short-wavelength (300-800nm) ultraviolet light irradiates the UV coating, exciting the photoinitiator (PI) in the coating to produce free radicals or cations. This triggers a reaction of the active groups, thus curing the coating into a film. Compared to traditional thermal curing, UV curing is fast, environmentally friendly, energy-saving, and low-carbon. UV-cured coatings do not require further processing, have lower requirements for formability, and operate in relatively gentle environments.

[0005] However, coated steel sheets must also undergo subsequent processing steps such as rolling and stamping, and their service environment is mostly outdoors with harsh conditions. This requires the UV coating to have excellent metal adhesion and formability. In addition, the outdoor service environment also requires the UV coating to have good wet adhesion and corrosion resistance. Summary of the Invention

[0006] One of the objectives of this invention is to provide a UV-coated steel sheet with good corrosion resistance and processing performance. This UV-coated steel sheet has excellent dry and wet adhesion performance, resistance to under-film corrosion, and processing performance.

[0007] To achieve the above objectives, the present invention provides a UV-coated steel sheet with good corrosion resistance and processability, comprising a coated steel sheet, wherein at least one surface of the coated steel sheet has a UV coating, and the UV coating contains the following effective components:

[0008] Composite resin A: 40-55 parts by weight; the composite resin A includes an aliphatic polyurethane acrylate oligomer A1 containing 15-25 wt% acrylate monomers with unsaturated double bonds, and an amine-modified epoxy diacrylate oligomer A2 containing 25-35 wt% acrylate monomers with unsaturated double bonds.

[0009] Organosilicon compound B: 5-12 parts by weight;

[0010] Monofunctional alkenyl unsaturated polymerizable monomer C: 12-22 parts by weight;

[0011] Acrylic phosphate compound D: 4-13 parts by weight;

[0012] Acrylic-based titanium or zirconium salt compounds E: 0.5-3 parts by weight;

[0013] UV photoinitiator F: 6-10 parts by weight.

[0014] In this invention, "Aliphatic polyurethane acrylate oligomer A1 containing 15-25 wt% acrylate monomers with unsaturated double bonds", "Aliphatic polyurethane acrylate oligomer A1 containing acrylate monomers with unsaturated double bonds", "Aliphatic polyurethane acrylate oligomer A1" and "A1" refer to a mixture of acrylate monomers and aliphatic polyurethane acrylate oligomers.

[0015] In this invention, "amine-modified epoxy diacrylate oligomer A2 containing 25-35 wt% acrylate monomers with unsaturated double bonds", "amine-modified epoxy diacrylate oligomer A2 with unsaturated double bonds", "amine-modified epoxy diacrylate oligomer A2" and "A2" refer to a mixture of acrylate monomers and amine-modified epoxy diacrylate oligomers.

[0016] Among them, aliphatic polyurethane acrylate oligomer A1 containing 15-25 wt% acrylate monomers with unsaturated double bonds means that aliphatic polyurethane acrylate oligomer A1 (i.e., aliphatic polyurethane acrylate oligomer + acrylate monomer) contains 15-25 wt% acrylate monomers by mass; similarly, amine-modified epoxy diacrylate oligomer A2 containing 25-35 wt% acrylate monomers with unsaturated double bonds means that amine-modified epoxy diacrylate oligomer A2 (i.e., amine-modified epoxy diacrylate oligomer + acrylate monomer) contains 25-35 wt% acrylate monomers by mass.

[0017] In this invention, the flexibility of the UV coating, its dry and wet adhesion to the metal substrate, and its adhesion to the topcoat are all inseparable from composite resin A. The polyurethane segments in aliphatic polyurethane acrylate oligomer A1, containing unsaturated double bonds in acrylate monomers, provide good coating flexibility. The amine-modified epoxy diacrylate oligomer A2, also containing unsaturated double bonds in acrylate monomers, provides the coating's adhesion to the metal substrate and its adhesion to the topcoat. In this invention, the inventors control the weight percentage of composite resin A to 40-55 parts because: when the weight percentage of composite resin A is less than 40 parts, the coating's flexibility and adhesion to the metal substrate decrease; when the weight percentage of composite resin A is greater than 55 parts, the coating's adhesion to the subsequent topcoat and its wet adhesion to the metal substrate decrease.

[0018] In some specific embodiments, the aliphatic polyurethane acrylate oligomer A1 with unsaturated double bonds can have the following properties: a viscosity of 10,000-20,000 mPa·s at 25°C, a molecular weight of 1,500-4,500, a functionality of 2, and a density of 1.1-1.3 g / m³. 2 The glass transition temperature (Tg) is 30-50℃.

[0019] In some specific embodiments, the amine-modified epoxy diacrylate oligomer A2 with unsaturated double bonds of acrylate monomers can have the following properties: a viscosity of 400-1300 mPa·s at 25°C, a functionality of 2, and a density of 1.1-1.3 g / m³. 2 Its glass transition temperature (Tg) is 65-85℃, and its acid value is 3-5 mg KOH / g.

[0020] In some embodiments, organosilicon compound B contains vinyl groups. In this invention, organosilicon compound B contains vinyl groups that can bond with composite resin A under UV light, which can further improve the wet adhesion performance and resistance to underfilm corrosion between the UV coating and the metal substrate. Furthermore, organosilicon compound B forms silanol groups under the action of moisture. These silanol groups can undergo a condensation reaction with the Me-OH groups (Me represents metal) on the surface of the metal substrate to form Si-O-Me covalent bonds, preventing the continued spread of corrosive media under the film, thereby improving the wet adhesion performance between the UV coating and the metal substrate interface. In addition, organosilicon compound B can also improve the adhesion between the UV coating and the topcoat (solvent-based or radiation-cured topcoat). In this invention, the inventors controlled the weight percentage of organosilicon compound B between 5 and 12 because: when the weight percentage of organosilicon compound B is less than 5 parts, it is impossible to guarantee that the coated steel plate has good wet adhesion and resistance to underfilm corrosion; when the weight percentage of organosilicon compound B is greater than 12 parts, it will reduce the surface energy of the coating, leading to pinhole problems in the subsequent topcoat coating and affecting the adhesion between the UV coating and the topcoat coating.

[0021] In this invention, the monofunctional alkenyl unsaturated polymerizable monomer C is an acrylic monomer with a high glass transition temperature (Tg). The monofunctional alkenyl unsaturated polymerizable monomer C can participate in the reaction during UV curing. Its monofunctionality and high glass transition temperature ensure a low curing shrinkage rate of the coating, without affecting the adhesion between the UV coating and the metal substrate. In this invention, the inventors control the weight percentage of the monofunctional alkenyl unsaturated polymerizable monomer C between 12 and 22 parts because: when the weight percentage of the monofunctional alkenyl unsaturated polymerizable monomer C is less than 12 parts, the coating has a low degree of curing, resulting in reduced dry and wet adhesion; when the weight percentage of the monofunctional alkenyl unsaturated polymerizable monomer C is greater than 22 parts, the curing shrinkage rate of the coating increases, affecting the dry adhesion performance between the coating and the metal substrate.

[0022] In this invention, acrylate phosphate compound D acts as an adhesion promoter. acrylate phosphate compound D can also perform micro-phosphating modification on the metal surface, improving the dry and wet adhesion of the UV coating to the metal substrate. In this invention, the inventors control the weight percentage of acrylate phosphate compound D to 4-13 parts because: when the weight percentage of acrylate phosphate compound D is less than 4 parts, it affects the dry and wet adhesion of the coating to the metal substrate; when the weight percentage of acrylate phosphate compound D is greater than 13 parts, it affects the adhesion performance of the coating to the topcoat coating.

[0023] In this invention, acrylic-based titanium or zirconium salt compounds E can act as interfacial corrosion inhibitors. The acrylic-based titanium or zirconium salt compounds E primarily enhance the resistance to under-film corrosion diffusion in UV coatings. This is because the acrylic groups can combine with acrylic resin to form a film during UV curing. When moisture in the air penetrates to the interface between the steel plate and the UV coating, the titanium or zirconium salt can undergo a passivation reaction with the metal substrate surface, forming a passivation layer that inhibits further corrosion diffusion by moisture or corrosive media. In this invention, the inventors control the weight percentage of acrylic-based titanium or zirconium salt compounds E to 0.5-3 parts because: when the weight percentage of acrylic-based titanium or zirconium salt compounds E is less than 0.5 parts, it does not provide interfacial corrosion inhibition; when the weight percentage of acrylic-based titanium or zirconium salt compounds E is greater than 3 parts, it affects the flexibility of the UV coating.

[0024] In this invention, UV photoinitiator F can initiate the resin polymerization reaction. UV photoinitiator F is primarily a free radical photoinitiator, which forms free radicals under UV light irradiation. These free radicals can initiate the polymerization reaction of acrylic double bonds in the coating to form a polymer, thereby achieving curing. In this invention, the inventors control the weight percentage of UV photoinitiator F to 6-10 parts because: when the weight percentage of UV photoinitiator F is less than 6 parts, the coating curing degree is low, the coating surface is sticky, affecting the subsequent application of the topcoat and the adhesion between the coating and the metal substrate; when the weight percentage of UV photoinitiator F is greater than 10 parts, the flexibility of the cured coating decreases.

[0025] Furthermore, in the UV-coated steel sheet of the present invention, the mass ratio of A1 to A2 is 1.5-4.5.

[0026] In this invention, the inventors control the mass ratio of A1 to A2 between 1.5 and 4.5 parts because: when the mass ratio of A1 to A2 is less than 1.5 parts, the flexibility of the coating will be insufficient; when the mass ratio of A1 to A2 is greater than 4.5 parts, the adhesion performance between the coating and the metal substrate and the topcoat coating will be relatively deteriorated.

[0027] Furthermore, in the UV-coated steel sheet of the present invention, the UV coating further contains at least one of the following effective components:

[0028] Rust-preventive pigment G: 1.5-4.5 parts by weight;

[0029] Opacifying pigment H: 6-10 parts by weight;

[0030] Additive I: 0.2-0.8 parts by weight; the additive includes at least one of dispersant, wetting agent, leveling agent, and anti-settling agent.

[0031] In this invention, the rust-preventive pigment G can prevent steel plates from rusting. When corrosive media (water, oxygen, etc.) penetrate through defects in the coating to the interface between the coating and the metal substrate, the metal atoms at the interface are oxidized, losing electrons to form metal ions, while oxygen gains electrons and is reduced to OH- ions, thus creating an alkaline environment at the cured coating / metal interface. Furthermore, the rust-preventive pigment G has a high specific surface area, enabling it to form silicate or silicate ions in the alkaline environment. These ions then react with the metal ions on the UV coating / metal interface to form a metal silicate salt protective layer, inhibiting further corrosion at the interface. In this invention, the inventors control the weight percentage of the rust-preventive pigment G between 1.5 and 4.5 because: when the weight percentage of the rust-preventive pigment G is less than 1.5 parts, the rust-preventive effect is not significant; when the weight percentage of the rust-preventive pigment G is greater than 4.5 parts, it affects the flexibility of the UV coating.

[0032] In some specific embodiments, the average particle size of the rust-preventive pigment G can be 4-5 μm, the pH can be 7.5-9, and the oil absorption value can be 210-260.

[0033] In this invention, the masking pigment H serves to cover the metal substrate, facilitating a good appearance after the topcoat is applied and cured. The inventors controlled the weight percentage of the masking pigment H to be between 6 and 10 parts because: when the weight percentage of the masking pigment H is less than 6 parts, the masking effect is not significant; when the weight percentage of the masking pigment H is greater than 10 parts, it affects the adhesion of the UV coating.

[0034] Furthermore, in the UV-coated steel sheet of the present invention, the acrylate monomer in the aliphatic polyurethane acrylate oligomer A1 with unsaturated double bonds includes at least one of the following: hydroxyethyl methacrylate, isobornyl acrylate, 3,3,5-trimethylcyclohexanol acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl ethoxyacrylate, cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, phenoxyethyl acrylate, and tripropylene glycol diacrylate.

[0035] Furthermore, in the UV-coated steel sheet of the present invention, the aliphatic polyurethane acrylate oligomer A1 with unsaturated double bonds has the following structural characteristics: it is a block copolymer whose main chain is composed of alternating polyether or polyester soft segments and urethane hard segments composed of isocyanate and chain extender, and the ends have photopolymerizable active groups (e.g., acrylate, methacrylate).

[0036] Furthermore, in the UV-coated steel sheet of the present invention, the acrylate monomer in the amine-modified epoxy diacrylate oligomer A2 with unsaturated double bonds includes at least one of the following: hydroxyethyl methacrylate, isobornyl acrylate, 3,3,5-trimethylcyclohexanol acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl ethoxyacrylate, cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, phenoxyethyl acrylate, and tripropylene glycol diacrylate.

[0037] Furthermore, in the UV-coated steel sheet of the present invention, the amine-modified epoxy diacrylate oligomer A2 containing unsaturated double bonds has the following structural characteristics: it is a polymer formed by introducing photopolymerizable acrylate groups into bisphenol A type epoxy resin through ring-opening with acrylic acid, and then introducing flexible ether amine side chains through secondary amine modification. Its main chain inherits from the bisphenol A type epoxy resin, its end groups are photopolymerizable acrylate groups, and its side groups consist of hydroxyl groups and ether amines. Furthermore, in the UV-coated steel sheet of the present invention, the organosilicon compound B includes at least one of the following: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, methylvinyldimethoxysilane, triethoxysilane propyl methacrylate, and vinyltris(2-methoxyethoxy)silane.

[0038] Furthermore, in the UV-coated steel sheet of the present invention, the monofunctional alkenyl unsaturated polymerizable monomer C includes at least one of the following: hydroxyethyl methacrylate, isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl ethoxyacrylate, cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, phenoxyethyl acrylate, and tripropylene glycol diacrylate.

[0039] Furthermore, in the UV-coated steel sheet of the present invention, the acrylate phosphate compound D includes at least one of the following: di(hydroxyethyl) phosphate, di(methacryloyloxyethyl) hydrogen phosphate, ethylene glycol methacrylate phosphate, and 2-hydroxyethyl methacrylate phosphate.

[0040] Furthermore, in the UV-coated steel sheet of the present invention, the acrylic-based titanium salt or zirconium salt compound E includes at least one of the following: zirconium acrylate, tetramethacrylic acid zirconium, and triisopropoxide titanium methacrylate.

[0041] Furthermore, in the UV-coated steel sheet of the present invention, the UV photoinitiator F includes at least one of the following: benzoin dimethyl ether, methyl benzoylformate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-(trimethylbenzoyl)di(p-tolyl)phosphine oxide, and 2-isopropylthioxanthraphenone.

[0042] Furthermore, in the UV-coated steel sheet of the present invention, the anti-rust pigment G comprises ion-exchange alkaline silica powder.

[0043] Furthermore, in the UV-coated steel sheet of the present invention, the masking pigment H includes, but is not limited to, titanium dioxide.

[0044] Furthermore, in the UV-coated steel sheet of the present invention, the thickness of the UV coating is 3-30 μm.

[0045] Furthermore, in the UV-coated steel sheet of the present invention, the coating of the coated steel sheet is a hot-dip galvanized layer, an electro-galvanized layer, a hot-dip aluminum-zinc layer, or a hot-dip zinc-aluminum-magnesium layer.

[0046] Another object of the present invention is to provide a UV coating for coated steel sheets. By applying the coating to the surface of the galvanized steel sheet, a UV coating can be obtained. The UV-coated steel sheet has excellent dry and wet adhesion properties, resistance to underfilm erosion, and processability.

[0047] To achieve the above objectives, the present invention provides a UV coating for coated steel sheets, the solids of which contain the following active ingredients:

[0048] Composite resin A: 40-55 parts by weight; the composite resin A includes an aliphatic polyurethane acrylate oligomer A1 containing 15-25 wt% acrylate monomers with unsaturated double bonds, and an amine-modified epoxy diacrylate oligomer A2 containing 25-35 wt% acrylate monomers with unsaturated double bonds.

[0049] Organosilicon compound B: 5-12 parts by weight;

[0050] Monofunctional alkenyl unsaturated polymerizable monomer C: 12-22 parts by weight;

[0051] Acrylic phosphate compound D: 4-13 parts by weight;

[0052] Acrylic-based titanium or zirconium salt compounds E: 0.5-3 parts by weight;

[0053] UV photoinitiator F: 6-10 parts by weight.

[0054] Furthermore, the UV coating of the present invention is solvent-free.

[0055] Furthermore, in the UV coating described in this invention, the mass ratio of A1 to A2 is 1.5-4.5.

[0056] Furthermore, in the UV coating of the present invention, the UV coating also contains at least one of the following active ingredients:

[0057] Rust-preventive pigment G: 1.5-4.5 parts by weight;

[0058] Opacifying pigment H: 6-10 parts by weight;

[0059] Additive I: 0.2-0.8 parts by weight; the additive includes at least one of dispersant, wetting agent, leveling agent, and anti-settling agent.

[0060] Furthermore, in the UV coating of the present invention, the acrylate monomer in the aliphatic polyurethane acrylate oligomer A1 with unsaturated double bonds includes at least one of the following: hydroxyethyl methacrylate, isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl ethoxyacrylate, cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, phenoxyethyl acrylate, and tripropylene glycol diacrylate.

[0061] Furthermore, in the UV coating of the present invention, the acrylate monomer in the amine-modified epoxy diacrylate oligomer A2 with unsaturated double bonds includes at least one of the following: hydroxyethyl methacrylate, isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl ethoxyacrylate, cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, phenoxyethyl acrylate, and tripropylene glycol diacrylate.

[0062] Furthermore, in the UV coating of the present invention, the organosilicon compound B includes at least one of the following: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, methylvinyldimethoxysilane, triethoxysilane propyl methacrylate, and vinyltri(2-methoxyethoxy)silane.

[0063] Furthermore, in the UV coating of the present invention, the monofunctional alkenyl unsaturated polymerizable monomer C includes at least one of the following: hydroxyethyl methacrylate, isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl ethoxyacrylate, cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, phenoxyethyl acrylate, and tripropylene glycol diacrylate.

[0064] Furthermore, in the UV coating of the present invention, the acrylate phosphate compound D includes at least one of the following: di(hydroxyethyl) phosphate, di(methacryloyloxyethyl) hydrogen phosphate, ethylene glycol methacrylate phosphate, and 2-hydroxyethyl methacrylate phosphate.

[0065] Furthermore, in the UV coating of the present invention, the acrylic-based titanium salt or zirconium salt compound E includes at least one of the following: zirconium acrylate, tetramethacrylic acid zirconium, and triisopropoxide titanium methacrylate.

[0066] Furthermore, in the UV coating of the present invention, the UV photoinitiator F includes at least one of the following: benzoin dimethyl ether, methyl benzoylformate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-(trimethylbenzoyl)di(p-tolyl)phosphine oxide, and 2-isopropylthioxanthraphenone.

[0067] Furthermore, in the UV coating of the present invention, the anti-rust pigment G comprises ion-exchange alkaline silica powder.

[0068] Furthermore, in the UV coating of the present invention, the masking pigment H includes, but is not limited to, titanium dioxide.

[0069] Another object of the present invention is to provide a method for manufacturing a UV-coated steel sheet with good corrosion resistance and processability, which can obtain a UV-coated steel sheet with good corrosion resistance and processability.

[0070] To achieve the above objectives, the present invention provides a method for manufacturing a UV-coated steel sheet with good corrosion resistance and processability, comprising the following steps:

[0071] The aforementioned UV coating is applied to the surface of the coated steel sheet;

[0072] UV curing is performed, with the UV curing irradiation energy controlled at 200-5000 mJ / cm². 2 To form the UV coating on the surface of the coated steel sheet.

[0073] Compared with existing technologies, the UV-coated steel sheet with good corrosion resistance and processing performance and its manufacturing method described in this invention have the following advantages and beneficial effects:

[0074] The UV-coated steel sheet with good corrosion resistance and processing performance described in this invention has excellent dry and wet adhesion performance and resistance to under-film corrosion, which can meet the requirements of subsequent processing and forming. It can be used alone in the service environment, and its good adhesion with the topcoat also makes it suitable as the initial coating for double-coated color steel sheets, providing it with good overall corrosion resistance. Detailed Implementation

[0075] The following will further explain and illustrate the UV-coated steel sheet with good corrosion resistance and processing performance and its manufacturing method according to the present invention with reference to specific embodiments. However, such explanation and illustration do not constitute an undue limitation on the technical solution of the present invention.

[0076] Examples 1-10 and Comparative Examples 1-11

[0077] The UV-coated steel sheets with good corrosion resistance and processing properties in Examples 1-10 and the UV-coated steel sheets in Comparative Examples 1-11 of this invention were all prepared using the following steps:

[0078] (1) Apply UV coating to the surface of the coated steel plate;

[0079] (2) Perform UV curing, controlling the UV curing irradiation energy to be 200-5000 mJ / cm. 2 (The irradiation energies used in the various embodiments and comparative examples are shown in Tables 1-3) to form a UV coating on the surface of the coated steel sheet.

[0080] In Examples 1-10 and Comparative Examples 1-11, the UV curing process parameters were as follows: the UV light source was a medium-pressure mercury lamp, the irradiation wavelength was between 200-1000 nm, the UV coating was cured under a nitrogen atmosphere, and the oxygen content during UV curing was less than 500 ppm.

[0081] It should be noted that this invention focuses on the excellent performance of the UV coating formed by UV curing of the designed coil steel coating, and there are no special limitations on the metal substrate. Those skilled in the art can select a suitable metal substrate according to specific needs in practical applications.

[0082] Furthermore, it should be noted that the effective components contained in the UV coating of the present invention are the same as those in the UV paint, therefore the two will not be described separately.

[0083] It is understood that the effective components contained in the UV coating of the present invention refer to the coating components before UV curing.

[0084] Tables 1-1 and 1-2 list the UV coatings of the UV-coated steel sheets of Examples 1-10 and Comparative Examples 1-11, as well as the types and contents of active ingredients in the UV coatings used.

[0085] Table 1-1.

[0086] Table 1-2. Note: In Table 1, A1-1 is hydroxyethyl methacrylate, A1-2 is isobornyl acrylate, A1-3 is 3,3,5-trimethylcyclohexanol acrylate, A1-4 is 3,3,5-trimethylcyclohexyl methacrylate, A1-5 is dicyclopentenyl ethoxyacrylate, A1-6 is cyclotrimethylolpropane methyl acetal acrylate, A1-7 is lauryl acrylate, A1-8 is phenoxyethyl acrylate, and A1-9 is tripropylene glycol diacrylate.

[0087] The aliphatic polyurethane acrylate oligomer in A1 of Table 1 was purchased from ZX Resins (China) Co., Ltd., and its brand name is [Brand Name Missing]. 8807 has the following properties: viscosity of 10000-20000 mPa·s at 25℃, molecular weight of 1500-4500, functionality of 2, and density of 1.1-1.3 g / m³. 2 The glass transition temperature (Tg) is 30-50℃.

[0088] In Table 1, A2-1 is hydroxyethyl methacrylate, A2-2 is isobornyl acrylate, A2-3 is 3,3,5-trimethylcyclohexanol acrylate, A2-4 is 3,3,5-trimethylcyclohexyl methacrylate, A2-5 is dicyclopentenyl ethoxyacrylate, A2-6 is cyclotrimethylolpropane methyl acetal acrylate, A2-7 is lauryl acrylate, A2-8 is phenoxyethyl acrylate, and A2-9 is tripropylene glycol diacrylate.

[0089] The amine-modified epoxy diacrylate oligomer in Table 1 (A2) was purchased from Changxing Special Materials (Suzhou) Co., Ltd., under the brand name ETERCURE 6235. Its properties meet the following requirements: viscosity of 400-1300 mPa·s at 25℃, functionality of 2, and density of 1.1-1.3 g / m³. 2 Its glass transition temperature (Tg) is 65-85℃, and its acid value is 3-5 mg KOH / g.

[0090] In Table 1, B1 is vinyltrimethoxysilane, B2 is vinyltriethoxysilane, B3 is vinyltriacetoxysilane, B4 is methylvinyldimethoxysilane, B5 is triethoxysilane propyl methacrylate, and B6 is vinyltri(2-methoxyethoxy)silane.

[0091] In Table 1, C1 is hydroxyethyl methacrylate, C2 is isobornyl acrylate, C3 is 3,3,5-trimethylcyclohexanol acrylate, C4 is 3,3,5-trimethylcyclohexyl methacrylate, C5 is dicyclopentenyl ethoxyacrylate, C6 is cyclotrimethylolpropane methyl acetal acrylate, C7 is lauryl acrylate, C8 is phenoxyethyl acrylate, and C9 is tripropylene glycol diacrylate.

[0092] In Table 1, D1 is di(hydroxyethyl) phosphate, D2 is di(methacryloyloxyethyl) hydrogen phosphate, D3 is ethylene glycol methacrylate phosphate, and D4 is 2-hydroxyethyl methacrylate phosphate.

[0093] In Table 1, E1 represents zirconium acrylate, E2 represents tetramethacrylic acid zirconium, and E3 represents triisopropoxide titanium methacrylate.

[0094] In Table 1, F1 is benzoin dimethyl ether, F2 is methyl benzoylformate, F3 is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, F4 is 1-hydroxy-cyclohexyl-phenyl ketone, F5 is 2,4,6-(trimethylbenzoyl)di(p-tolyl)phosphine oxide, and F6 is 2-isopropylthioxanthraphenone.

[0095] In Table 1, G1 is ion-exchange type alkaline silica powder.

[0096] In Table 1, I1 is the dispersant (purchased from BYK Chemicals, brand name DISPERBYK-2013), and I2 is the wetting agent (purchased from Evonik, brand name...). I3 is a leveling agent (purchased from BYK Chemicals, brand name BYK 333), and I4 is an anti-settling agent (purchased from Degussa, brand name R972). Furthermore, other dispersants, wetting agents, leveling agents, and anti-settling agents known to those skilled in the art are also feasible and are within the scope of this invention.

[0097] In Table 1, the A1 / A2 mass ratio of 0 in Comparative Example 10 means that the effective component of the UV coating contains 41 parts by mass of A2 and no A1.

[0098] It should be noted that the rust-preventive pigment G in the embodiments of the present invention is an ion-exchange type alkaline silica powder with an average particle size of 4 μm, a pH of 8, and an oil absorption value of 230. However, other ion-exchange type alkaline silica powders with an average particle size between 4-5 μm, a pH of 7.5-9, and an oil absorption value of 210-260 are also feasible for the present invention. In addition, other pigments that can achieve rust prevention function, known to those skilled in the art, are also feasible and are within the scope of protection of the present invention.

[0099] It should be noted that the masking pigment H in the embodiments of the present invention is titanium dioxide, but other pigments that can achieve the masking function known to those skilled in the art are also feasible.

[0100] Furthermore, it should be noted that although A1, A2, B, C, D, E, F, and I in the above embodiments all use a single substance, it is also feasible to use multiple substances that meet the requirements in combination in other embodiments.

[0101] Table 1-3 lists the coating types, coating thicknesses, and UV curing process parameters for the UV-coated steel sheets of Examples 1-10 and Comparative Examples 1-11.

[0102] Table 1-3.

[0103] Accordingly, to verify the beneficial effects of the UV coating formed after UV curing as designed in this invention, samples of the UV-coated steel plates prepared in Examples 1-10 and Comparative Examples 1-11 were taken, cut into standard-sized samples, and subjected to the following tests to obtain test data for evaluating various properties. The evaluation results are listed in Table 4. The specific test items and test methods are shown in Table 2 below.

[0104] Table 2 lists the test methods and evaluation criteria for the coated steel plates in Examples 1-10 and Comparative Examples 1-11 of this invention.

[0105] Table 2.

[0106] Accordingly, to further verify the adhesion performance and overall corrosion resistance of the UV coating and topcoat coating formed after UV curing as designed in this invention, the coated steel plates in Examples 1-10 and Comparative Examples 1-11 were coated and cured with topcoat to prepare double-coated steel plates. The topcoat type was a conventional solvent-based polyester coating for coiled steel (purchased from Shanghai Huayi Fine Chemical Co., Ltd., grade CH310WB301), with a film thickness of 15 μm. The curing process parameters were: PMT 232℃ and curing time 30 s. The following tests were then conducted to obtain experimental data for evaluating various properties, and the evaluation results are listed in Table 4. Specific test items and methods are shown in Table 3 below.

[0107] Table 3 lists the test methods and evaluation criteria for the double-coated (UV coating + topcoat coating) steel plates in Examples 1-10 and Comparative Examples 1-11 of this invention.

[0108] Table 3.

[0109] Table 4 lists the performance evaluation results of Examples 1-10 and Comparative Examples 1-11 of the present invention.

[0110] Table 4.

[0111] As can be seen from Table 4 above, the UV-coated steel sheets in Examples 1-10 prepared by the manufacturing method described in this invention have excellent dry and wet adhesion properties and resistance to under-film corrosion. Furthermore, the double-coated steel sheets after being coated with a cured topcoat exhibit good adhesion and overall corrosion resistance.

[0112] It should be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A UV-coated steel sheet with good corrosion resistance and processability, comprising a coated steel sheet, characterized in that, At least one surface of the coated steel sheet has a UV coating, the UV coating containing the following active ingredients: Composite resin A: 40-55 parts by weight; the composite resin A includes an aliphatic polyurethane acrylate oligomer A1 containing 15-25 wt% acrylate monomers with unsaturated double bonds, and an amine-modified epoxy diacrylate oligomer A2 containing 25-35 wt% acrylate monomers with unsaturated double bonds. Organosilicon compound B: 5-12 parts by weight; Monofunctional alkenyl unsaturated polymerizable monomer C: 12-22 parts by weight; Acrylic phosphate compound D: 4-13 parts by weight; Acrylic-based titanium or zirconium salt compounds E: 0.5-3 parts by weight; UV photoinitiator F: 6-10 parts by weight.

2. The UV-coated steel sheet as described in claim 1, characterized in that, The mass ratio of A1 to A2 is 1.5-4.

5.

3. The UV-coated steel sheet as described in claim 1, characterized in that, The UV coating also contains at least one of the following active ingredients: Rust-preventive pigment G: 1.5-4.5 parts by weight; Opacifying pigment H: 6-10 parts by weight; Additive I: 0.2-0.8 parts by weight; the additive includes at least one of dispersant, wetting agent, leveling agent, and anti-settling agent.

4. The UV-coated steel sheet as described in claim 1, characterized in that, The acrylate monomers in the aliphatic polyurethane acrylate oligomer A1 containing unsaturated double bonds include at least one of the following: hydroxyethyl methacrylate, isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl ethoxylate, cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, phenoxyethyl acrylate, and tripropylene glycol diacrylate. The acrylate monomers in the amine-modified epoxy diacrylate oligomer A2 containing unsaturated double bonds include at least one of the following: hydroxyethyl methacrylate, isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl ethoxylate, cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, phenoxyethyl acrylate, and tripropylene glycol diacrylate. The organosilicon compound B includes at least one of the following: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, methylvinyldimethoxysilane, triethoxysilane propyl methacrylate, and vinyltri(2-methoxyethoxy)silane. The monofunctional alkenyl unsaturated polymerizable monomer C includes at least one of the following: hydroxyethyl methacrylate, isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl ethoxylate, cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, phenoxyethyl acrylate, and tripropylene glycol diacrylate. The acrylate phosphate compound D includes at least one of the following: di(hydroxyethyl) phosphate, di(methacryloyloxyethyl) hydrogen phosphate, ethylene glycol methacrylate phosphate, and 2-hydroxyethyl methacrylate phosphate. The acrylate-based titanium or zirconium salt compound E includes at least one of the following: zirconium acrylate, tetramethacrylic acid zirconium, triisopropoxide titanium methacrylate; The UV photoinitiator F includes at least one of the following: benzoin dimethyl ether, methyl benzoylformate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-(trimethylbenzoyl)di(p-tolyl)phosphine oxide, and 2-isopropylthioxanthraphenone.

5. The UV-coated steel sheet as described in claim 3, characterized in that, The rust-preventive pigment G comprises ion-exchange alkaline silica powder.

6. The UV-coated steel sheet as described in claim 1, characterized in that, The thickness of the UV coating is 3-30 μm.

7. The UV-coated steel sheet as described in claim 1, characterized in that, The coating of the coated steel sheet is a hot-dip galvanized layer, an electro-galvanized layer, a hot-dip aluminum-zinc layer, or a hot-dip zinc-aluminum-magnesium layer.

8. A UV coating for coated steel sheets, characterized in that, Its solid components contain the following active ingredients: Composite resin A: 40-55 parts by weight; the composite resin A includes an aliphatic polyurethane acrylate oligomer A1 containing 15-25 wt% acrylate monomers with unsaturated double bonds, and an amine-modified epoxy diacrylate oligomer A2 containing 25-35 wt% acrylate monomers with unsaturated double bonds. Organosilicon compound B: 5-12 parts by weight; Monofunctional alkenyl unsaturated polymerizable monomer C: 12-22 parts by weight; Acrylic phosphate compound D: 4-13 parts by weight; Acrylic-based titanium or zirconium salt compounds E: 0.5-3 parts by weight; UV photoinitiator F: 6-10 parts by weight.

9. The UV coating as described in claim 8, characterized in that, The mass ratio of A1 to A2 is 1.5-4.

5.

10. The UV coating as described in claim 8, characterized in that, The UV coating also contains at least one of the following active ingredients: Rust-preventive pigment G: 1.5-4.5 parts by weight; Opacifying pigment H: 6-10 parts by weight; Additive I: 0.2-0.8 parts by weight; the additive includes at least one of dispersant, wetting agent, leveling agent, and anti-settling agent.

11. The UV coating as described in claim 8, characterized in that, The acrylate monomers in the aliphatic polyurethane acrylate oligomer A1 containing unsaturated double bonds include at least one of the following: hydroxyethyl methacrylate, isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl ethoxylate, cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, phenoxyethyl acrylate, and tripropylene glycol diacrylate. The acrylate monomers in the amine-modified epoxy diacrylate oligomer A2 containing unsaturated double bonds include at least one of the following: hydroxyethyl methacrylate, isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl ethoxylate, cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, phenoxyethyl acrylate, and tripropylene glycol diacrylate. The organosilicon compound B includes at least one of the following: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, methylvinyldimethoxysilane, triethoxysilane propyl methacrylate, and vinyltri(2-methoxyethoxy)silane. The monofunctional alkenyl unsaturated polymerizable monomer C includes at least one of the following: hydroxyethyl methacrylate, isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl ethoxylate, cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, phenoxyethyl acrylate, and tripropylene glycol diacrylate. The acrylate phosphate compound D includes at least one of the following: di(hydroxyethyl) phosphate, di(methacryloyloxyethyl) hydrogen phosphate, ethylene glycol methacrylate phosphate, and 2-hydroxyethyl methacrylate phosphate.

12. The UV coating as described in claim 8, characterized in that, The acrylate-based titanium or zirconium salt compound E includes at least one of the following: zirconium acrylate, tetramethacrylic acid zirconium, and triisopropoxide titanium methacrylate.

13. The UV coating as described in claim 8, characterized in that, The UV photoinitiator F includes at least one of the following: benzoin dimethyl ether, methyl benzoylformate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-(trimethylbenzoyl)di(p-tolyl)phosphine oxide, and 2-isopropylthioxanthraphenone.

14. The UV coating as described in claim 10, characterized in that, The rust-preventive pigment G comprises ion-exchange alkaline silica powder.

15. A method for manufacturing a UV-coated steel sheet with good corrosion resistance and processability, characterized in that, Including the following steps: The UV coating as described in any one of claims 8-14 is applied to the surface of the coated steel sheet; UV curing is performed, with the UV curing irradiation energy controlled at 200-5000 mJ / cm². 2 To form the UV coating on the surface of the coated steel sheet.

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