A metal medium UV printing method

Abstract

The application relates to the technical field of UV printing, in particular to a metal medium UV printing method which adopts a ceramizing agent, electrostatic powder spraying and acrylic ester ultraviolet ink to perform coating treatment on a metal medium, wherein the powder raw material of the electrostatic powder spraying is a modified thermosetting resin modified by an amino silane coupling agent, after the modified thermosetting resin is sprayed onto a ceramizing layer, the amino silane coupling agent and the silane coupling agent in the ceramizing layer will produce a coupling reaction, the binding force of the ceramizing layer and the electrostatic powder spraying layer is improved, the photoinitiator in the acrylic ester ultraviolet ink can strengthen the coupling reaction between the amino silane coupling agent and the acrylic ester resin, the binding force of the acrylic ester ultraviolet ink layer and the classic powder spraying layer is improved, and the adhesion of the coating on the surface of the metal medium is significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of UV printing, in particular to a metal medium UV printing method. BACKGROUND

[0002] The coating of metal surface is a widely used corrosion protection method, and the metal surface usually needs to be treated before coating, the purpose of which is to establish a non-metallic coating protective layer on the surface of the protected metal medium, so as to improve the adhesion between the metal medium and the coating film, thereby improving the protection of the coating on the metal. The traditional pretreatment process is phosphating process, but the phosphating process has the problems of poor production continuity, complex process, use of large amount of strong acid and strong base, and large pollution emission. Therefore, in order to solve the above problems, the skilled in the art discloses a phosphating alternative technology, such as zirconium and silane, among which the zirconium treatment agent can form a ceramic conversion film on the surface of the substrate, the rust prevention and coating adhesion are much higher than that of iron phosphating, and it can be combined with processes such as powder spraying, electrophoresis and paint spraying, and has the characteristics of environmental protection, energy saving, simple operation and low cost. At present, the zirconium treatment agent also has high requirements for workpiece material and water quality, and there is a problem of rusting for some cold rolled plates.

[0003] In view of the above problems of the zirconium treatment agent, the prior art CN111040485A discloses an environmentally friendly metal surface treatment agent and a use method, which is phosphorus-free, chromium-free, environmentally friendly, non-toxic and harmless, can form a chemical film on the metal surface, and has excellent rust prevention performance and long-term corrosion inhibition performance. However, the present application found that when the above metal surface treatment agent is used, the coupling agent and the electrostatic powder spraying and the acrylate ultraviolet ink are used together, the coupling agent has the problem of poor adhesion of the electrostatic powder spraying layer and the acrylate ultraviolet ink layer, and the coating peeling problem easily occurs. SUMMARY

[0004] The present application provides a metal medium UV printing method to solve the problem of poor adhesion between the electrostatic powder spraying layer and the acrylate ultraviolet ink layer formed by the metal coating treatment in the prior art. The method uses a coupling agent, electrostatic powder spraying and acrylate ultraviolet ink to coat the metal medium. The powder raw material of the electrostatic powder spraying is a modified thermosetting resin modified by an amino silane coupling agent. After the modified thermosetting resin is sprayed onto the coupling layer, the amino silane coupling agent and the silane coupling agent in the coupling layer will produce a coupling reaction, which improves the adhesion between the coupling layer and the electrostatic powder spraying layer. The photoinitiator in the acrylate ultraviolet ink can strengthen the coupling reaction between the amino silane coupling agent and the acrylate resin, which improves the adhesion between the acrylate ultraviolet ink layer and the electrostatic powder spraying layer, and significantly improves the adhesion of the coating on the metal medium surface.

[0005] The specific technical scheme of the present application is as follows:

[0006] A metal medium UV printing method, comprising the following steps: pretreating the surface of a metal medium to form a pretreated metal, cleaning the pretreated metal using a cleaning agent to form a metal medium negative, placing the metal medium negative in a UV printing device and using an acrylate UV ink for UV printing, the pretreatment comprising electrostatic powder spraying, the powder raw material of the electrostatic powder spraying being 70-80 parts of resin powder, 5-10 parts of curing agent, 3-6 parts of dispersing agent, and 5-10 parts of pigment; the resin powder being a modified thermosetting resin, and the modified thermosetting resin being made of an amino silane coupling agent modified thermosetting epoxy resin.

[0007] The present application provides a metal medium UV printing method, which uses a ceramization agent, electrostatic powder spraying and acrylate UV ink for coating treatment of the metal medium. The method can significantly improve the adhesion of the electrostatic powder spraying layer to the ceramization layer and the acrylate UV ink layer, and significantly improve the adhesion of the coating on the surface of the metal medium. It is found in actual operation that the adhesion between the ceramization layer, the electrostatic powder spraying layer and the acrylate UV ink layer is poor and peeling easily occurs. After analysis, it is found that the ceramization agent of the present application uses the environmentally friendly metal surface treatment agent disclosed in CN111040485A. The ceramization agent can form a ceramic film layer on the metal surface, so that the metal surface can form a chemical film layer that can receive a non-metal coating. In addition, the silane coupling agent contained in the ceramization agent can couple with the electrostatic powder spraying layer, thereby improving the adhesion of the electrostatic powder spraying layer to the ceramization layer.

[0008] In addition, it is found that the powder raw material of the current electrostatic spraying powder mainly comprises thermosetting resin, curing agent, dispersing agent and pigment. The thermosetting resin usually uses thermosetting epoxy resin. Although epoxy resin has strong adhesion, the compatibility of epoxy resin with acrylate is poor, which leads to poor adhesion of the acrylate UV ink to the electrostatic spraying powder layer, and the acrylate UV ink layer is extremely easy to peel off from the electrostatic spraying powder layer.

[0009] Therefore, the application proposes to use silane coupling agent to strengthen the binding force between the electrostatic spraying powder layer and the acrylate UV ink, in addition, since the electrostatic spraying powder is a solid powder, and the silane coupling agent mainly exists in liquid form, the application selects to use the silane coupling agent to modify the epoxy resin to make modified epoxy resin, and then the modified epoxy resin is made into powder for electrostatic powder spraying, the epoxy resin modified by the silane coupling agent can further couple with the silane coupling agent in the ceram layer, so as to further improve the binding force between the ceram layer and the electrostatic powder layer, and the silane coupling agent in the electrostatic powder layer can also couple with the acrylate UV ink layer, so as to significantly improve the binding force between the acrylate UV ink layer and the electrostatic powder spraying layer; the application also selects the silane coupling agent, and the application finds that when the amino silane coupling agent is used, the toughness of the electrostatic powder spraying layer and the acrylate UV ink layer is significantly improved, and the electrostatic powder spraying layer and the acrylate UV ink layer can still not fall off after impact, and the impact resistance of the electrostatic powder spraying layer and the acrylate UV ink layer is significantly improved.

[0010] Preferably, the electrostatic powder spraying conditions are as follows: electrostatic spraying gun pressure 0.15-0.25 MPa, voltage 110-135 kV, current 50-70 uA, curing temperature 160-200 DEG C, and curing time 15-25 min.

[0011] Preferably, the amino silane coupling agent is one or more of KH-550, H792 and KH602.

[0012] Preferably, the mass ratio of the amino silane coupling agent and the thermosetting epoxy resin is 0.5-5:99.5-95.

[0013] Preferably, the pretreatment further comprises rust removal, oil removal and ceramization.

[0014] Preferably, the ceramization is performed by using a ceramization agent, and the ceramization agent is metasilicate pentahydrate, polyvinyl alcohol, zirconium oxide, potassium zirconium fluoride, sodium nitrite, nonylphenol polyoxyethylene ether, silane coupling agent, wetting agent, film-forming aid, ethanol and water.

[0015] Preferably, the ceramization conditions are as follows: soaking for 1-3 min and drying at 100-120 DEG C.

[0016] Preferably, the acrylate UV ink comprises acrylate, photoinitiator and pigment.

[0017] Preferably, the acrylate is alkyl acrylate and 1,6-hexanediol diacrylate.

[0018] As a preference, the photoinitiator is 1,6-hexanediol diacrylate, 2,4,6-trimethylbenzoyl, 2-hydroxy-4-hydroxyethyl-2-methylpropiophenone and 2-methyl-1-(4-methylthiophenyl)-2-morpholin-1-propanone.

[0019] As a preference, the cleaning agent is a solvent, a surfactant, a chelating agent and a pH regulator.

[0020] Compared with the prior art, the application has the following technical effects:

[0021] The method adopts a ceramifying agent, electrostatic powder spraying and acrylic ester ultraviolet ink for coating treatment of the metal medium, wherein the powder raw material of the electrostatic powder spraying is a modified thermosetting resin modified by an amino silane coupling agent, after the modified thermosetting resin is sprayed onto the ceramifying layer, the amino silane coupling agent and the silane coupling agent in the ceramifying layer will produce a coupling reaction, improving the bonding force between the ceramifying layer and the electrostatic powder spraying layer, the photoinitiator in the acrylic ester ultraviolet ink can strengthen the coupling reaction between the amino silane coupling agent and the acrylic ester resin, improving the bonding force between the acrylic ester ultraviolet ink layer and the electrostatic powder spraying layer, and significantly improving the adhesion of the coating on the surface of the metal medium. DETAILED DESCRIPTION

[0022] The application will be further described below in combination with examples.

[0023] Example 1

[0024] A metal medium UV printing method, the metal medium is a cast iron plate, comprising the following steps:

[0025] Step one: using a rust remover to perform rust removal treatment on the surface of the cast iron plate, after the rust removal treatment is completed, using 240 mesh sandpaper to polish the surface of the cast iron plate, so that the metal surface becomes smooth, then using 0.5 mm sand particles to perform sand blasting treatment for 30 s, and using 1 mm sand particles to perform sand blasting treatment for 10 s, the included angle of the sand blasting direction is 90 °;

[0026] Step two: immersing the cast iron plate in a degreasing agent (16 g / L of phosphoric acid and 6 g / L of emulsifier OP-10) to perform degreasing treatment, after the degreasing treatment, using water to rinse the cast iron plate, and rinsing for 5 min;

[0027] Step three: immerse the cast iron plate in a ceramization agent (components: sodium silicate 6%, chitosan 5%, urotropin azo 0.1%, OP-10 emulsifier 0.08%, catechol 0.05%, PM-WET100 silane coupling agent 0.02%, dodecanol ester 0.02%, ethanol 6%, water balance, pH value 7) for 3 min, and then dry the cast iron plate in an environment at 110°C to synthesize a ceramization layer on the surface of the cast iron plate. The thickness of the ceramization layer is 80 nm. The cast iron plate is cleaned, blown dry, and baked using water;

[0028] Step four: use an electrostatic spray gun to electrostatically powder spray the cast iron plate to form an electrostatic powder spray layer on the ceramization layer. Connect a high-voltage negative electrode to the metal spray ring and anode needle of the electrostatic spray gun head, and connect the ground to the cast iron plate to form a positive electrode, so as to form a strong electrostatic field between the spray gun and the workpiece. Compressed air carries the powder from the powder supply cylinder to the spray ring and anode needle of the spray gun through the powder pipe. The powder carries a negative charge and is sprayed onto the surface of the positively charged cast iron plate. The pressure of the electrostatic spray gun is 0.2 MPa, the voltage is 120 kV, and the current is 60 uA. Then, the sprayed cast iron plate is sent into a curing oven for curing at 170°C for 20 min.

[0029] The raw material for electrostatic powder spraying is 75 parts of resin powder (modified thermosetting resin), 10 parts of curing agent (trisglycidyl isocyanurate), 5 parts of dispersing agent (sodium tripolyphosphate), and 10 parts of pigment;

[0030] The modified thermosetting powder is made by mixing and crushing amino silane coupling agent KH-550 and thermosetting epoxy resin at a mass ratio of 2:98;

[0031] Step five: wipe the surface of the cast iron plate with a cleaning agent, and then place the cast iron plate in a UV printing device and use acrylic ester UV ink to perform UV printing to form a coated metal. The acrylic ester UV ink includes 40 parts of acrylic alkyl ester, 40 parts of 1,6-hexanediol diacrylate, 5 parts of 1,6-hexanediol diacrylate, 5 parts of 2,4,6-trimethylbenzoyl, 5 parts of 2-hydroxy-4-hydroxyethyl-2-methylbenzophenone, and 5 parts of 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone.

[0032] Example 2:

[0033] A metal medium UV printing method, the metal medium is a cast iron plate, comprising the following steps:

[0034] Step one: use the rust remover to treat the surface of the cast iron plate, after the rust treatment, use 240 grit sandpaper to polish the surface of the cast iron plate, so that the metal surface becomes smooth, then use 0.5 mm sand particles to spray sand for 30 s, and use 1 mm sand particles to spray sand for 10 s, the angle of the spraying direction is 90 °;

[0035] Step two: soak the cast iron plate in the oil removal agent (16 g / L of phosphoric acid and 6 g / L of emulsifier OP-10) for oil removal treatment, then rinse the cast iron plate with water for 5 min after the oil removal treatment;

[0036] Step three: soak the cast iron plate in the vitrification agent (components are sodium silicate 6%, chitosan 5%, urotropinazole 0.1%, OP-10 emulsifier 0.08%, catechol 0.05%, PM-WET100 silane coupling agent 0.02%, dodecanol ester 0.02%, ethanol 6%, water balance, pH value 7) for 3 min, then dry it at 100 ℃ to form a vitrification layer on the surface of the cast iron plate, the thickness of the vitrification layer is 80 nm, then clean, blow dry and bake the cast iron plate with water;

[0037] Step four: use the electrostatic spray gun to electrostatically powder spray the cast iron plate to form an electrostatic powder spray layer on the vitrification layer, connect the high-voltage negative electrode to the metal spray ring and the positive needle on the head of the electrostatic spray gun, connect the ground to the cast iron plate to form a positive electrode, so as to form a strong electrostatic field between the spray gun and the workpiece, the compressed air carries the powder from the powder supply cylinder to the spray ring and the needle of the spray gun through the powder pipe, the powder carries negative charge and is sprayed on the surface of the positively charged cast iron plate, the pressure of the electrostatic spray gun is 0.15 MPa, the voltage is 110 kV, and the current is 50 uA, then put the sprayed cast iron plate into the curing oven to cure at 160 ℃ for 25 min;

[0038] The raw material of the electrostatic powder spraying is 75 parts of resin powder (modified thermosetting resin), 10 parts of curing agent (isocyanuric acid triglycidyl ester), 5 parts of dispersing agent (sodium tripolyphosphate) and 10 parts of pigment;

[0039] The modified thermosetting powder is made by mixing and crushing the amino silane coupling agent KH-550 and the thermosetting epoxy resin in a mass ratio of 0.5:99.5;

[0040] Step five: wipe the surface of the cast iron plate with a cleaning agent, and after drying, place the cast iron plate in a UV printing device and use acrylate UV ink to print a coated metal, the acrylate UV ink includes 40 parts of alkyl acrylate, 40 parts of 1,6-hexanediol diacrylate, 5 parts of 1,6-hexanediol diacrylate, 5 parts of 2,4,6-trimethylbenzoyl, 5 parts of 2-hydroxy-4-hydroxyethyl-2-methylbenzophenone, and 5 parts of 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone.

[0041] Example 3:

[0042] A metal medium UV printing method, the metal medium is a cast iron plate, comprising the following steps:

[0043] Step one: use a rust remover to treat the surface of the cast iron plate, after the rust removal treatment, use 240 grit sandpaper to polish the surface of the cast iron plate to make the metal surface smooth, then use 0.5 mm sand particles to sandblast for 30 s, and then use 1 mm sand particles to sandblast for 10 s, the included angle of the sandblasting direction is 90 °;

[0044] Step two: soak the cast iron plate in a degreasing agent (16 g / L of phosphoric acid and 6 g / L of emulsifier OP-10) for degreasing treatment, and then rinse the cast iron plate with water for 5 min after the degreasing treatment;

[0045] Step three: soak the cast iron plate in a vitrification agent (components are sodium silicate 6%, chitosan 5%, urotropin azo 0.1%, OP-10 emulsifier 0.08%, catechol 0.05%, PM-WET100 silane coupling agent 0.02%, dodecanol ester 0.02%, ethanol 6%, water balance, pH value 7) for 3 min, and then dry the cast iron plate in an environment of 100-120 °C to synthesize a vitrification layer on the surface of the cast iron plate, the thickness of the vitrification layer is 80 nm, and then clean, blow dry and dry the cast iron plate with water;

[0046] Step four: use an electrostatic spray gun to electrostatically powder spray the cast iron plate to form an electrostatic powder spray layer on the vitrification layer, connect a high-voltage negative electrode to the metal spray ring and the electrode needle of the electrostatic spray gun head, and connect the ground of the cast iron plate to form a positive electrode, so as to form a strong electrostatic field between the spray gun and the workpiece, the compressed air carries the powder from the powder supply cylinder to the spray ring and the electrode needle of the spray gun through the powder pipe, the powder carries a negative charge and is sprayed on the surface of the positively charged cast iron plate, the pressure of the electrostatic spray gun is 0.25 MPa, the voltage is 135 kV, and the current is 70 uA, and then the sprayed cast iron plate is sent into a curing oven for curing at 200 °C for 15 min;

[0047] The raw material of electrostatic powder spraying is 80 parts of resin powder (modified thermosetting resin), 5 parts of curing agent (triglycidyl isocyanurate), 5 parts of dispersing agent (sodium tripolyphosphate) and 10 parts of pigment;

[0048] The modified thermosetting powder is prepared by mixing and crushing the amino silane coupling agent KH-550 and the thermosetting epoxy resin in a mass ratio of 5:95;

[0049] Step five: wipe the surface of the cast iron plate with a cleaning agent, and after drying, place the cast iron plate in a UV printing device and use acrylate UV ink to perform UV printing to form a coated metal, the acrylate UV ink comprising 40 parts of alkyl acrylate, 40 parts of 1,6-hexanediol diacrylate, 5 parts of 1,6-hexanediol diacrylate, 5 parts of 2,4,6-trimethylbenzoyl, 5 parts of 2-hydroxy-4-hydroxyethyl-2-methylbenzophenone and 5 parts of 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone.

[0050] Example 4:

[0051] A metal medium UV printing method, the metal medium being a cast iron plate, comprising the following steps:

[0052] Step one: use a rust remover to perform rust removal treatment on the surface of the aluminum plate, and after the rust removal treatment is completed, use 240 grit sandpaper to polish the surface of the aluminum plate to make the metal surface smooth, then use 0.5 mm sand particles to perform sandblasting treatment for 30 s, and then use 1 mm sand particles to perform sandblasting treatment for 10 s, the included angle of the sandblasting direction being 90 °;

[0053] Step two: immerse the aluminum plate in a degreasing agent (16 g / L of phosphoric acid and 6 g / L of emulsifier OP-10) to perform degreasing treatment, and after the degreasing treatment, use water to rinse the cast iron plate for 5 min;

[0054] Step three: immerse the aluminum plate in a ceramization agent (components being sodium silicate 6%, chitosan 5%, urotropinazole 0.1%, OP-10 emulsifier 0.08%, catechol 0.05%, PM-WET100 silane coupling agent 0.02%, dodecanol ester 0.02%, ethanol 6%, water balance, pH value 7) for 3 min, and after the immersion is completed, dry the aluminum plate in an environment of 100-120 °C to synthesize a ceramization layer on the surface of the aluminum plate, the thickness of the ceramization layer being 80 nm, and then use water to clean, blow dry and bake dry the aluminum plate;

[0055] Step four: using an electrostatic spray gun to electrostatically powder spray the aluminum plate on the ceram layer to form an electrostatic powder spray layer, connecting a high-voltage negative electrode to the metal spray ring and the electrode needle of the electrostatic spray gun head, and connecting the ground to the aluminum plate to form a positive electrode, so as to form a strong electrostatic field between the spray gun and the workpiece. Compressed air carries the powder from the powder supply cylinder to the spray ring and the electrode needle of the spray gun through the powder pipe. The powder carries a negative charge and is sprayed onto the surface of the positive cast iron plate. The electrostatic spray gun pressure is 0.15-0.25 MPa, the voltage is 110-135 kV, and the current is 50-70 uA. Then the sprayed aluminum plate is sent into a curing oven for curing at 160-200 ℃ for 15-25 min;

[0056] The raw material for electrostatic powder spraying is 70-80 parts of resin powder (modified thermosetting resin), 5-10 parts of curing agent (isocyanuric acid triglycidyl ester), 3-6 parts of dispersing agent (sodium tripolyphosphate), and 5-10 parts of pigment;

[0057] The modified thermosetting powder is made by mixing and solidifying an amino silane coupling agent H792 and a thermosetting epoxy resin in a mass ratio of 3:97, and then crushing them;

[0058] Step five: using a cleaning agent to wipe the surface of the cast iron plate, and then placing the aluminum plate in a UV printing device and using an acrylate UV ink to perform UV printing to form a coated metal. The acrylate UV ink includes 40 parts of an acrylic alkyl ester, 40 parts of 1,6-hexanediol diacrylate, 5 parts of 1,6-hexanediol diacrylate, 5 parts of 2,4,6-trimethylbenzoyl, 5 parts of 2-hydroxy-4-hydroxyethyl-2-methylbenzophenone, and 5 parts of 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone.

[0059] Example 5:

[0060] A metal medium UV printing method, the metal medium being a cast iron plate, comprising the following steps:

[0061] Step one: using a rust remover to perform rust removal treatment on the surface of the cold-rolled plate. After the rust removal treatment is completed, using 240-grit sandpaper to polish the surface of the cold-rolled plate to make the metal surface smooth. Then using 0.5 mm sand particles to perform sandblasting treatment for 30 s, and using 1 mm sand particles to perform sandblasting treatment for 10 s. The included angle of the sandblasting direction is 90 °;

[0062] Step two: immersing the cold-rolled plate in a degreasing agent (16 g / L of phosphoric acid and 6 g / L of emulsifier OP-10) to perform degreasing treatment. After the degreasing treatment, using water to rinse the cold-rolled plate for 5 min;

[0063] Step three: soak the cold-rolled plate in the ceramization agent (components are sodium silicate 6%, chitosan 5%, urotropin azo 0.1%, OP-10 emulsifier 0.08%, catechol 0.05%, PM-WET100 silane coupling agent 0.02%, dodecanol ester 0.02%, ethanol 6%, and water in balance, pH value 7) for 3 min, and then dry it in an environment of 100-120°C to form a ceramization layer on the surface of the cold-rolled plate, with a thickness of 80 nm; wash, blow dry and bake the cold-rolled plate with water;

[0064] Step four: use an electrostatic spray gun to electrostatically powder spray the cold-rolled plate to form an electrostatic powder spraying layer on the ceramization layer, connect a high-voltage negative electrode to the metal spray ring and anode needle of the head of the electrostatic spray gun, and connect the ground to the cold-rolled plate to form a positive electrode, so as to form a strong electrostatic field between the spray gun and the workpiece; compressed air carries the powder from the powder supply cylinder to the spray ring and anode needle of the spray gun through the powder pipe, and the powder carries a negative charge and is sprayed on the surface of the cold-rolled plate with a positive charge; the pressure of the electrostatic spray gun is 0.15-0.25 MPa, the voltage is 110-135 kV, and the current is 50-70 uA; then put the sprayed cast iron plate into a curing oven for curing at 160-200°C for 15-25 min;

[0065] The raw material for electrostatic powder spraying is 70-80 parts of resin powder (modified thermosetting resin), 5-10 parts of curing agent (isocyanuric acid triglycidyl ester), 3-6 parts of dispersing agent (sodium tripolyphosphate), and 5-10 parts of pigment;

[0066] The modified thermosetting powder is made by mixing and solidifying 2 parts of amino silane coupling agent KH602 and 98 parts of thermosetting epoxy resin in a mass ratio;

[0067] Step five: wipe the surface of the cold-rolled plate with a cleaning agent, and then place it in a UV printing device and use acrylate UV ink to perform UV printing to form a coated metal; the acrylate UV ink includes 40 parts of acrylate alkyl ester, 40 parts of 1,6-hexanediol diacrylate, 5 parts of 1,6-hexanediol diacrylate, 5 parts of 2,4,6-trimethylbenzoyl, 5 parts of 2-hydroxy-4-hydroxyethyl-2-methylbenzophenone, and 5 parts of 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone.

[0068] Comparative Example 1

[0069] Compared with Example 1, the powder for electrostatic powder spraying in Comparative Example 1 uses a thermosetting epoxy resin instead of a modified thermosetting resin, including the following steps:

[0070] Step one: use rust remover to remove rust on the surface of cast iron plate, after rust removal, use 240 grit sandpaper to polish the surface of cast iron plate, so that the metal surface becomes smooth, then use 0.5 mm sand to spray sand treatment for 30 s, then use 1 mm sand to spray sand treatment for 10 s, the angle of spray sand direction is 90 °;

[0071] Step two: soak the cast iron plate in oil removal agent (16 g / L of phosphoric acid and 6 g / L of emulsifier OP-10) for oil removal treatment, then rinse the cast iron plate with water for 5 min after oil removal treatment;

[0072] Step three: soak the cast iron plate in ceramic agent (components are sodium silicate 6%, chitosan 5%, urotropin azo 0.1%, OP-10 emulsifier 0.08%, catechol 0.05%, PM-WET100 silane coupling agent 0.02%, dodecanol ester 0.02%, ethanol 6%, water balance, pH value 7) for 3 min, then dry it at 110 ℃ to form a ceramic layer on the surface of the cast iron plate, the thickness of the ceramic layer is 80 nm, then clean, blow dry and bake the cast iron plate with water;

[0073] Step four: use electrostatic spray gun to electrostatically spray powder on the cast iron plate to form an electrostatic powder coating layer on the ceramic layer, connect the high-voltage negative electrode to the metal spray ring and the positive needle of the electrostatic spray gun head, connect the ground to the cast iron plate to form a positive electrode, so as to form a strong electrostatic field between the spray gun and the workpiece, the compressed air carries the powder from the powder supply cylinder to the spray ring and the needle of the spray gun through the powder pipe, the powder carries negative charge and is sprayed on the surface of the positively charged cast iron plate, the pressure of the electrostatic spray gun is 0.2 MPa, the voltage is 120 kV, and the current is 60 uA, then put the sprayed cast iron plate into the curing oven to cure at 170 ℃ for 20 min;

[0074] The raw material of the electrostatic powder spraying is 75 parts of resin powder (thermosetting epoxy resin), 10 parts of curing agent (isocyanuric acid triglycidyl ester), 5 parts of dispersing agent (sodium tripolyphosphate) and 10 parts of pigment;

[0075] Step five: use cleaner to wipe the surface of the cast iron plate, then put the cast iron plate into the UV printing device and use acrylate UV ink to print the cast iron plate to form a coated metal, the acrylate UV ink includes 40 parts of acrylic alkyl ester, 40 parts of 1,6-hexanediol diacrylate, 5 parts of 1,6-hexanediol diacrylate, 5 parts of 2,4,6-trimethylbenzoyl, 5 parts of 2-hydroxy-4-hydroxyethyl-2-methylbenzophenone and 5 parts of 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone.

[0076] Comparative example 2:

[0077] Compared with Example 1, the thermosetting epoxy resin in Comparative Example 2 was modified by trimethoxysilane, and other conditions were the same as those in Example 1.

[0078] Test Example:

[0079] The adhesion and impact resistance of the coated metal prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were tested; the adhesion test included a first adhesion test and a second adhesion test,

[0080] The first adhesion test procedure was as follows: cutting was performed on the coated metal by a cutting machine until the metal material was reached, and then 100 square grids with a side length of 1 mm were formed, and then the coated metal was peeled off by a glass tape, and the adhesion was evaluated by counting the number of the coated metal remaining after peeling.

[0081] The second adhesion test procedure was as follows: the coated metal was immersed in boiling water for two hours, and then the first adhesion test was performed again.

[0082] The impact resistance was tested according to GB / T 11548, and a falling weight impact tester was used, a 5 kg falling weight was freely dropped from a certain height to impact the coated metal, and the energy required to cause 50% damage was recorded to calculate the impact resistance.

[0083] The test results are shown in Table 1.

[0084] Table 1 Test Results

[0085] Primary adhesion (pieces) Secondary adhesion (pieces) Impact resistance (J / m) Example 1 100 100 15.3 Example 2 100 99 15.1 Example 3 100 99 15.2 Example 4 100 100 16.7 Example 5 100 100 18.3 Comparative Example 1 88 73 10.3 Comparative Example 2 95 88 11.6

[0086] As shown in Table 1, the test results of the first adhesion of Examples 1 to 5 were 100, and the test results of the second adhesion were 99 to 100, which indicated that the coating layer on the surface of the coated metal prepared by the method provided by the present application had excellent adhesion.

[0087] In Comparative Example 1, a conventional epoxy resin was used, and the test results of the first adhesion of Comparative Example 1 were 88, and the test results of the second adhesion of Comparative Example 1 were 73, which indicated that the adhesion of the coating layer on the surface of the coated metal of Comparative Example 1 was significantly lower than that of Example 1; in Comparative Example 2, a conventional silane coupling agent was used to modify the thermosetting epoxy resin, and the test results of the first adhesion of Comparative Example 2 were 95, and the test results of the second adhesion of Comparative Example 2 were 88, which indicated that the adhesion of the coating layer on the surface of the coated metal of Comparative Example 2 was lower than that of Example 1, and the results indicated that the adhesion of the coating layer on the surface of the coated metal was significantly improved after the thermosetting epoxy resin was modified by the amino silane coupling agent used in the present application, and the effect of the amino silane coupling agent was more significant.

[0088] In addition, from the impact resistance performance results of Example 1, Comparative Example 1 and Comparative Example 2, it can be found that the use of the amino silane coupling agent can significantly improve the impact resistance performance of the coating layer on the coated metal surface, and the coated metal can still have excellent protection performance during the collision process.

[0089] The above is only the preferred embodiment of the present application, not any limitation on the present application, any simple modification, change and equivalent transformation of the above embodiment according to the technical essence of the present application still belong to the protection scope of the technical solution of the present application.

Claims

1. A metal medium UV printing method, characterized by, The method comprises the following steps: The surface of the metal medium is pretreated to form a pretreated metal, the pretreated metal is cleaned with a cleaning agent to form a metal medium negative plate, the metal medium negative plate is placed in a UV printing device and UV printing is performed using an acrylate UV ink, and the pretreatment comprises electrostatic powder spraying; The pretreatment comprises ceramization, the ceramization is performed using a ceramization agent, and the ceramization agent is metasilicate pentahydrate, polyvinyl alcohol, zirconium oxide, potassium zirconium fluoride, sodium nitrite, nonylphenol polyoxyethylene ether, silane coupling agent, wetting agent, film-forming aid, ethanol and water; The acrylate UV ink comprises acrylate, photoinitiator and pigment; the photoinitiator is 1,6-hexanediol diacrylate, 2,4,6-trimethylbenzoyl, 2-hydroxy-4-hydroxyethyl-2-methylbenzophenone and 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone; The powder raw material for the electrostatic powder spraying is 70-80 parts of resin powder, 5-10 parts of curing agent, 3-6 parts of dispersing agent and 5-10 parts of pigment; the resin powder is modified thermosetting resin, and the modified thermosetting resin is made of amino silane coupling agent modified thermosetting epoxy resin.

2. The method of claim 1, wherein, The conditions for the electrostatic powder spraying are 0.15-0.25 MPa of electrostatic spray gun pressure, 110-135 kV of voltage, 50-70 uA of current, 160-200 ℃ of curing temperature and 15-25 min of curing time.

3. The method of claim 1 wherein, The pretreatment further comprises rust removal and oil removal.

4. The method of claim 1 wherein, The soaking time of the ceramization is 1-3 minutes.

5. The method of claim 1 wherein, The drying temperature of the ceramization is 100-120 ℃.

6. The method of claim 5, wherein, The drying temperature of the ceramization is 110 ℃.

7. The method of claim 1 wherein, The acrylate is 10-50 parts of alkyl acrylate and 5-40 parts of 1,6-hexanediol diacrylate.