Acid and alkali resistant UV curing coating and preparation method thereof

Abstract

The invention relates to the technical field of coatings, and discloses an acid and alkali resistant UV curing coating and a preparation method thereof. The prepared UV curing coating is prepared from the following raw materials in parts by weight: 40 to 60 parts of acrylic resin, 3 to 8 parts of pentaerythritol tetraacrylate, 3 to 7 parts of silicon dioxide, 3 to 5 parts of a photoinitiator, 6 to 12 parts of a composite reinforcing agent, 0.2 to 0.6 part of a flatting agent, 1 to 2 parts of a dispersing agent, 0.5 to 1.5 parts of a de-foaming agent and 15 to 25 parts of water. A coating film obtained after the coating is subjected to ultraviolet curing has excellent acid and alkali resistance, salt spray resistance and adhesive force and can be widely applied to the surface of a metal base material, and the metal base material is protected against corrosion of corrosive media such as acid, alkali and salt.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to an acid and alkali resistant UV-curable coating and its preparation method. Background Technology

[0002] In recent years, ultraviolet (UV) curing technology has been widely used in industrial protection, automotive, electronics, and metal packaging due to its significant advantages such as high efficiency, energy saving, and environmental friendliness. Acrylic resin, as the main resin in UV-curable coatings, produces cured films with good mechanical properties and optical transparency. However, traditional acrylic-based UV-curable coatings still have inherent defects in crosslinking density, compactness, and chemical stability, resulting in insufficient resistance to chemical corrosion, especially strong acids, strong alkalis, and salt spray. This greatly limits their application in harsh environments (such as the inner walls of chemical equipment, metal components in coastal areas, and electronic component packaging).

[0003] Currently, traditional methods for improving the corrosion resistance of UV-cured coatings mainly include: (1) synthesizing novel multifunctional monomers or oligomers to increase crosslinking density; and (2) introducing inorganic nanofillers (such as SiO2, TiO2, clay, etc.) to enhance the physical barrier effect. However, these methods have obvious limitations. Conventional inorganic nanofillers have poor compatibility with organic resin matrices, are prone to agglomeration, causing internal defects in the coating, and are difficult to disperse uniformly in the UV curing system, affecting the transparency and mechanical properties of the coating. Although silane coupling agents are usually used to modify the surface of fillers, the improvement effect is limited, the interfacial bonding is still not ideal, and the interface is easily damaged in long-term corrosive environments. Therefore, developing a novel composite reinforcing material that can significantly improve the acid and alkali resistance and salt spray resistance of UV-cured coatings has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an acid and alkali resistant UV-curable coating and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] An acid and alkali resistant UV-curable coating comprises the following raw materials in parts by weight: 40-60 parts acrylic resin, 3-8 parts pentaerythritol tetraacrylate, 3-7 parts silica, 3-5 parts photoinitiator, 6-12 parts composite reinforcing agent, 0.2-0.6 parts leveling agent, 1-2 parts dispersant, 0.5-1.5 parts defoamer, and 15-25 parts water;

[0007] Furthermore, the photoinitiator is one of 2-hydroxy-2-methylphenylpropanone, 1-hydroxycyclohexylphenyl methyl ketone, and photoinitiator TPO;

[0008] Furthermore, the leveling agent is BYK-310 leveling agent;

[0009] Furthermore, the dispersant is a BYK-2013 type dispersant;

[0010] Furthermore, the defoamer is BYK-024 defoamer;

[0011] The composite reinforcing agent is prepared by the following steps:

[0012] Step A1: Mix cashew phenol and glyoxylic acid in a mixture of water and ethanol, stir until homogeneous, heat to 100°C, introduce nitrogen gas, and simultaneously add cyclohexane and p-toluenesulfonic acid. Maintain the temperature and reflux for 1-2 hours. Stop introducing nitrogen gas and continue the reaction under vacuum for 2 hours. Purify and dry to obtain terminal aldehyde cashew phenol.

[0013] Further, in step A1, the ratio of cashew phenol, glyoxylic acid, water, ethanol, cyclohexane and p-toluenesulfonic acid is 0.01-0.03 mol: 0.01-0.03 mol: 80 mL: 20 mL: 10 mL: 0.004-0.012 g;

[0014] Step A2: Under nitrogen atmosphere, 1-(2-aminoethyl)-2-imidazolinone and terminal aldehyde cashew phenol are mixed and stirred evenly in toluene, heated to 110°C and stirred under reflux for 4.5-5.5 h, allowed to stand at room temperature, benzene is added and allowed to stand for 10 min, filtered, filter cake is collected and washed, and vacuum dried to obtain imidazolinone-cashew phenol.

[0015] Further, in step A2, the ratio of 1-(2-aminoethyl)-2-imidazolinone, terminal aldehyde cashew phenol, toluene, and benzene is 0.01-0.03 mol: 0.01-0.03 mol: 100 mL: 100 mL;

[0016] Step A3: Under nitrogen conditions, mix and stir imidazolinone-cashew phenol, triethylamine and N,N-dimethylformamide evenly, add 3-chloropropyltrimethoxysilane and stir thoroughly, then heat to 85℃ and reflux for 3-4 hours. The mixture is then rotary evaporated, purified, rotary evaporated a second time and dried to obtain the organic modifier.

[0017] Further, in step A3, the ratio of imidazolinone-cainol, triethylamine, N,N-dimethylformamide, and 3-chloropropyltrimethoxysilane is 0.01-0.02 mol: 0.011-0.022 mol: 50 mL: 0.011-0.022 mol;

[0018] Step A4: Stir ZIF-67 in a mixture of water and ethanol until homogeneous, add organic modifier, heat to 35℃ and stir for 12-16 hours, wash and dry to obtain composite reinforcing agent;

[0019] Further, in step A4, the mass ratio of ZIF-67, water, ethanol and organic modifier is 0.5:10:20:1-3.

[0020] A method for preparing an acid and alkali resistant UV-curable coating includes the following steps:

[0021] Weigh the raw materials according to the weight proportions, mix the acrylic resin, dispersant and water evenly, then add silica, pentaerythritol tetraacrylate, composite reinforcing agent, leveling agent and defoamer and mix evenly. Finally, add the photoinitiator and mix thoroughly to obtain an acid and alkali resistant UV curing coating.

[0022] The beneficial effects of this invention are:

[0023] The UV-curable coating prepared by this invention is made of acrylic resin as the main matrix resin, and with the addition of photoinitiator, silica, pentaerythritol tetraacrylate, composite reinforcing agent, leveling agent, dispersant, defoamer and water. The coating film obtained after UV curing has excellent acid and alkali resistance, salt spray resistance and excellent adhesion. It can be widely used on the surface of metal substrates to protect the metal substrates from corrosion by corrosive media such as acids, alkalis and salts.

[0024] The composite reinforcing agent introduced into the UV-curable coating of this invention is prepared by grafting an organic modifier onto the surface of ZIF-67. This greatly improves the compatibility between ZIF-67 and the acrylic resin matrix, prevents nanoparticle aggregation, and achieves uniform dispersion. The uniformly dispersed ZIF-67 forms a tortuous path in the coating, which greatly extends the H... + and OH - The pathway of ion diffusion into the substrate improves the coating's acid and alkali resistance, and the modification by the organic modifier enhances the stability of ZIF-67 in acidic solutions. The imino (-NH-) and imidazolinone groups on the organic modifier are basic and can actively capture small amounts of H⁺ that have penetrated in, causing protonation and thus consuming corrosive ions, delaying their erosion of the resin and substrate. For alkaline erosion, the carbon-carbon double bond structure contained in the organic modifier (the side chain of cashew phenol contains at least one carbon-carbon double bond) can participate in the coating curing process, enhancing the crosslinking density of the coating, so that the stable crosslinking network itself provides good resistance.

[0025] The hydrophobic long chains of cashew phenol side chains in organic modifiers form a strong hydrophobic layer, greatly hindering the penetration of water and oxygen. Without water, the electrochemical corrosion circuit cannot form. -They cannot penetrate to the surface of the metal substrate; while imidazolinone and imino are also excellent adsorption corrosion inhibitors. The lone pair electrons in their molecules can be strongly chemically adsorbed on the surface of the metal substrate (such as iron) to form a dense monomolecular protective film. This film occupies the active sites for corrosion reaction and repels Cl⁻ and H₂O from approaching, thereby improving the adhesion of the coating to the substrate surface and the salt spray resistance. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The ZIF-67 used in this embodiment was prepared by the following steps: 0.08 mol of cobalt nitrate hexahydrate and 0.32 mol of 2-methylimidazole were dissolved in 50 mL of methanol respectively. The two solutions were then mixed and stirred thoroughly with magnetic stirring for 30 min. Subsequently, the mixed solution was allowed to stand at room temperature for 24 h. The supernatant was poured off, and the resulting precipitate was washed three times by centrifugation with methanol and dried in an oven at 60 °C. The prepared ZIF-67 was then collected.

[0028] In this embodiment, cashew phenol was purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd., and the side chain of cashew phenol contains at least one carbon-carbon double bond.

[0029] Example 1: The composite reinforcing agent was prepared by the following steps:

[0030] Step A1: Mix 0.01 mol cashew nut powder and 0.01 mol glyoxylic acid in a mixture of 80 mL water and 20 mL ethanol, stir until homogeneous, heat to 100 °C, introduce nitrogen gas, and simultaneously add 10 mL cyclohexane and 0.004 g p-toluenesulfonic acid. Maintain the temperature and reflux for 1 h, stop introducing nitrogen gas and continue the reaction under vacuum for 2 h, purify and dry to obtain terminal aldehyde cashew nut powder;

[0031] Step A2: Under nitrogen atmosphere, 0.01 mol of 1-(2-aminoethyl)-2-imidazolinone and 0.01 mol of terminal aldehyde cashew phenol were mixed and stirred in 100 mL of toluene until homogeneous. The mixture was heated to 110 °C and stirred under reflux for 4.5 h. After standing to room temperature, 100 mL of benzene was added and allowed to stand for 10 min. The mixture was then filtered, the filter cake was collected and washed, and dried under vacuum to obtain imidazolinone-cashew phenol.

[0032] Step A3: Under nitrogen atmosphere, mix 0.01 mol imidazolinone-cashew phenol, 0.011 mol triethylamine and 50 mL N,N-dimethylformamide and stir until homogeneous. Add 0.011 mol 3-chloropropyltrimethoxysilane and stir thoroughly. Heat to 85°C and reflux for 3 hours. Then, evaporate by rotary evaporation, purify, evaporate by rotary evaporation again, and dry to obtain the organic modifier.

[0033] Step A4: Stir 0.5g ZIF-67 in a mixture of 10g water and 20g ethanol until homogeneous, add 1g organic modifier, heat to 35℃ and stir for 14h, wash and dry to obtain the composite reinforcing agent.

[0034] Example 2: The composite reinforcing agent was prepared by the following steps:

[0035] Step A1: Mix 0.02 mol cashew nut powder and 0.02 mol glyoxylic acid in a mixture of 80 mL water and 20 mL ethanol, stir until homogeneous, heat to 100 °C, introduce nitrogen gas, and simultaneously add 10 mL cyclohexane and 0.008 g p-toluenesulfonic acid. Maintain the temperature and reflux for 1.5 h, stop introducing nitrogen gas and continue the reaction under vacuum for 2 h, purify and dry to obtain terminal aldehyde cashew nut powder;

[0036] Step A2: Under nitrogen atmosphere, 0.02 mol of 1-(2-aminoethyl)-2-imidazolinone and 0.02 mol of terminal aldehyde cashew phenol were mixed and stirred in 100 mL of toluene until homogeneous. The mixture was heated to 110 °C and stirred under reflux for 5 h. After standing to room temperature, 100 mL of benzene was added and the mixture was allowed to stand for 10 min. The mixture was then filtered, the filter cake was collected and washed, and dried under vacuum to obtain imidazolinone-cashew phenol.

[0037] Step A3: Under nitrogen atmosphere, mix 0.015 mol imidazolinone-cashew phenol, 0.016 mol triethylamine and 50 mL N,N-dimethylformamide and stir until homogeneous. Add 0.016 mol 3-chloropropyltrimethoxysilane and stir thoroughly. Heat to 85°C and reflux for 3.5 h. Then, rotary evaporate, purify, rotary evaporate again, and dry to obtain the organic modifier.

[0038] Step A4: Stir 0.5g ZIF-67 in a mixture of 10g water and 20g ethanol until homogeneous, add 2g organic modifier, heat to 35℃ and stir for 14h, wash and dry to obtain composite reinforcing agent.

[0039] Example 3: The composite reinforcing agent was prepared by the following steps:

[0040] Step A1: Mix 0.03 mol cashew nut powder and 0.03 mol glyoxylic acid in a mixture of 80 mL water and 20 mL ethanol, stir until homogeneous, heat to 100 °C, introduce nitrogen gas, and simultaneously add 10 mL cyclohexane and 0.012 g p-toluenesulfonic acid. Maintain the temperature and reflux for 2 hours. Stop introducing nitrogen gas and continue the reaction under vacuum for 2 hours. Purify and dry to obtain terminal aldehyde cashew nut powder.

[0041] Step A2: Under nitrogen atmosphere, 0.03 mol of 1-(2-aminoethyl)-2-imidazolinone and 0.03 mol of terminal aldehyde cashew phenol were mixed and stirred in 100 mL of toluene until homogeneous. The mixture was heated to 110 °C and stirred under reflux for 5.5 h. After standing to room temperature, 100 mL of benzene was added and allowed to stand for 10 min. The mixture was then filtered, the filter cake was collected and washed, and dried under vacuum to obtain imidazolinone-cashew phenol.

[0042] Step A3: Under nitrogen atmosphere, mix 0.02 mol imidazolinone-cashew phenol, 0.022 mol triethylamine and 50 mL N,N-dimethylformamide and stir until homogeneous. Add 0.022 mol 3-chloropropyltrimethoxysilane and stir thoroughly. Heat to 85°C and reflux for 4 hours. Then, evaporate by rotary evaporation, purify, evaporate by rotary evaporation again, and dry to obtain the organic modifier.

[0043] Step A4: Stir 0.5g ZIF-67 in a mixture of 10g water and 20g ethanol until homogeneous, add 3g organic modifier, heat to 35℃ and stir for 16h, wash and dry to obtain composite reinforcing agent.

[0044] Example 4: A method for preparing an acid and alkali resistant UV-curable coating includes the following steps:

[0045] 40 parts acrylic resin, 3 parts pentaerythritol tetraacrylate, 3 parts silica, 3 parts 2-hydroxy-2-methylphenylacetone, 6 parts of the composite reinforcing agent prepared in Example 1, 0.2 parts of BYK-310 leveling agent, 1 part of BYK-2013 dispersant, 0.5 parts of BYK-024 defoamer, and 15 parts of water.

[0046] Weigh the raw materials according to the weight parts, mix the acrylic resin, BYK-2013 dispersant and water evenly, then add silica, pentaerythritol tetraacrylate, the composite reinforcing agent prepared in Example 1, BYK-310 leveling agent and BYK-024 defoamer and mix evenly. Finally, add 2-hydroxy-2-methylphenylacetone and mix thoroughly to obtain an acid and alkali resistant UV curing coating.

[0047] Example 5: A method for preparing an acid and alkali resistant UV-curable coating includes the following steps:

[0048] 50 parts acrylic resin, 5 parts pentaerythritol tetraacrylate, 5 parts silica, 4 parts 1-hydroxycyclohexylphenyl ketone, 9 parts of the composite reinforcing agent prepared in Example 2, 0.4 parts of BYK-310 leveling agent, 1.5 parts of BYK-2013 dispersant, 1 part of BYK-024 defoamer, and 20 parts of water.

[0049] Weigh the raw materials according to the weight parts, mix the acrylic resin, BYK-2013 dispersant and water evenly, then add silica, pentaerythritol tetraacrylate, the composite reinforcing agent prepared in Example 2, BYK-310 leveling agent and BYK-024 defoamer and mix evenly. Finally, add 1-hydroxycyclohexylphenyl ketone and mix thoroughly to obtain an acid and alkali resistant UV curing coating.

[0050] Example 6: A method for preparing an acid and alkali resistant UV-curable coating includes the following steps:

[0051] 60 parts acrylic resin, 8 parts pentaerythritol tetraacrylate, 7 parts silica, 5 parts photoinitiator TPO, 12 parts composite reinforcing agent prepared in Example 3, 0.6 parts BYK-310 leveling agent, 2 parts BYK-2013 dispersant, 1.5 parts BYK-024 defoamer, and 25 parts water.

[0052] Weigh the raw materials according to the weight parts, mix the acrylic resin, BYK-2013 dispersant and water evenly, then add silica, pentaerythritol tetraacrylate, the composite reinforcing agent prepared in Example 3, BYK-310 leveling agent and BYK-024 defoamer and mix evenly. Finally, add the photoinitiator TPO and mix thoroughly to obtain the acid and alkali resistant UV curing coating.

[0053] Comparative Example 1: This comparative example is a UV-curable coating. The difference between this example and Example 6 is that the composite reinforcing agent prepared in Example 3 was not added. All other aspects are the same.

[0054] Comparative Example 2: This comparative example is a UV-curable coating. The difference between this example and Example 6 is that ZIF-67 is used instead of the composite reinforcing agent prepared in Example 3. All other aspects are the same.

[0055] Comparative Example 3: This comparative example is a UV-curable coating. The difference between this example and Example 6 is that the organic modifier prepared in Example 3 is used instead of the composite reinforcing agent prepared in Example 3. All other aspects are the same.

[0056] The UV-curable coatings prepared in Examples 4-6 and Comparative Examples 1-3 were subjected to performance tests:

[0057] Salt spray resistance test: The salt spray resistance of the coating film was tested according to GB / T 1771-2007 "Determination of resistance to neutral salt spray of paints and varnishes";

[0058] Acid and alkali resistance tests: The acid and alkali resistance of the coating film were tested according to GB / T 9274-1988 "Determination of resistance to liquid media for paints and varnishes";

[0059] Adhesion test: The adhesion of the coating film was tested according to GB / T 9286-1998 "Cross-cut test of paint and varnish film";

[0060] The test results are shown in Table 1:

[0061] Table 1: Performance Test Results

[0062]

[0063] As can be seen from Table 1, the UV-curable coating prepared by this invention not only has excellent acid and alkali resistance, but also excellent salt spray resistance and adhesion. When applied to the surface of metal substrates, it can effectively protect the metal substrates from corrosion.

[0064] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the inventive concept, they should all fall within the protection scope of the present invention.

Claims

1. An acid and alkali resistant UV-curable coating, characterized in that, The raw materials include the following parts by weight: 40-60 parts acrylic resin, 3-8 parts pentaerythritol tetraacrylate, 3-7 parts silica, 3-5 parts photoinitiator, 6-12 parts composite reinforcing agent, 0.2-0.6 parts leveling agent, 1-2 parts dispersant, 0.5-1.5 parts defoamer, and 15-25 parts water; The composite reinforcing agent is prepared by stirring an organic modifier and ZIF-67 at 35°C for 12-16 hours. The organic modifier is prepared by refluxing imidazolinone-cashew phenol and 3-chloropropyltrimethoxysilane at 85°C under nitrogen for 3-4 hours. The imidazolinone-cashew phenol is prepared by refluxing 1-(2-aminoethyl)-2-imidazolinone and terminal aldehyde cashew phenol at 110°C for 4.5-5.5 hours. The imidazolinone-cashew phenol is prepared by refluxing cashew phenol and glyoxylic acid at 100°C under nitrogen for 1-2 hours, then stopping the nitrogen flow and continuing the reaction under vacuum for 2 hours.

2. The acid and alkali resistant UV-curable coating according to claim 1, characterized in that, The photoinitiator is one of 2-hydroxy-2-methylphenylpropanone, 1-hydroxycyclohexylphenyl methyl ketone, and photoinitiator TPO.

3. The acid and alkali resistant UV-curable coating according to claim 1, characterized in that, The leveling agent is BYK-310 leveling agent, the dispersant is BYK-2013 dispersant, and the defoamer is BYK-024 defoamer.

4. The acid and alkali resistant UV-curable coating according to claim 1, characterized in that, The composite reinforcing agent is prepared by the following steps: Step A1: Mix cashew phenol and glyoxylic acid in a mixture of water and ethanol, stir until homogeneous, heat to 100°C, introduce nitrogen gas, and simultaneously add cyclohexane and p-toluenesulfonic acid. Maintain the temperature and reflux for 1-2 hours. Stop introducing nitrogen gas and continue the reaction under vacuum for 2 hours. Purify and dry to obtain terminal aldehyde cashew phenol. Step A2: Under nitrogen atmosphere, 1-(2-aminoethyl)-2-imidazolinone and terminal aldehyde cashew phenol are mixed and stirred evenly in toluene, heated to 110°C and stirred under reflux for 4.5-5.5 h, allowed to stand at room temperature, benzene is added and allowed to stand for 10 min, filtered, filter cake is collected and washed, and vacuum dried to obtain imidazolinone-cashew phenol. Step A3: Under nitrogen conditions, mix and stir imidazolinone-cashew phenol, triethylamine and N,N-dimethylformamide evenly, add 3-chloropropyltrimethoxysilane and stir thoroughly, then heat to 85℃ and reflux for 3-4 hours. The mixture is then rotary evaporated, purified, rotary evaporated a second time and dried to obtain the organic modifier. Step A4: Stir ZIF-67 in a mixture of water and ethanol until homogeneous, add organic modifier, heat to 35℃ and stir for 12-16 hours, wash and dry to obtain composite reinforcing agent.

5. The acid and alkali resistant UV-curable coating according to claim 4, characterized in that, In step A1, the ratio of cashew phenol, glyoxylic acid, water, ethanol, cyclohexane and p-toluenesulfonic acid is 0.01-0.03 mol: 0.01-0.03 mol: 80 mL: 20 mL: 10 mL: 0.004-0.012 g.

6. The acid and alkali resistant UV-curable coating according to claim 4, characterized in that, In step A2, the ratio of 1-(2-aminoethyl)-2-imidazolinone, terminal aldehyde cashew phenol, toluene, and benzene is 0.01-0.03 mol: 0.01-0.03 mol: 100 mL: 100 mL.

7. The acid and alkali resistant UV-curable coating according to claim 4, characterized in that, In step A3, the ratio of imidazolinone-cashew phenol, triethylamine, N,N-dimethylformamide and 3-chloropropyltrimethoxysilane is 0.01-0.02 mol: 0.011-0.022 mol: 50 mL: 0.011-0.022 mol.

8. The acid and alkali resistant UV-curable coating according to claim 4, characterized in that, In step A4, the mass ratio of ZIF-67, water, ethanol and organic modifier is 0.5:10:20:1-3.

9. A method for preparing an acid and alkali resistant UV-curable coating according to any one of claims 1-8, characterized in that, Includes the following steps: Weigh the raw materials according to the weight proportions, mix the acrylic resin, dispersant and water evenly, then add silica, pentaerythritol tetraacrylate, composite reinforcing agent, leveling agent and defoamer and mix evenly. Finally, add the photoinitiator and mix thoroughly to obtain an acid and alkali resistant UV curing coating.

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