Cathode electrodeposition coating with antibacterial property and preparation method thereof

Abstract

The invention discloses a cathode electrodeposition coating with antibacterial property, the coating is prepared from antibacterial emulsion and color paste according to a weight ratio of 5: 1, and the antibacterial emulsion comprises a curing agent of parachloroxylenol modified epoxy resin and parachloroxylenol modified isocyanate. The bath solution obtained by matching the antibacterial emulsion with the HLS universal color paste is good in antibacterial property after circulation, the product storage stability is excellent, the long-acting antibacterial property of the coating is improved, meanwhile, the excellent mechanical property and chemical medium resistance are kept, and the application of the electrophoretic coating in a poor environment scene is met.

Description

Technical Field

[0001] The invention relates to the technical field of electrophoretic coating, and in particular to a cathode electrodeposition coating with antibacterial properties and a preparation method thereof. Background Art

[0002] After decades of development, cathodic electrophoretic coating has obvious process advantages: 1. High degree of automation, can be used for assembly line operation; 2. Strong controllability, film thickness can be effectively controlled; 3. Good penetration, improve the coating of inner cavity and gap, improve anti-corrosion performance; 4. High coating utilization rate; 5. Low pollution and high safety. These advantages have been widely used in the automotive industry and other metal coating fields such as building materials, hardware, home appliances, furniture, etc. The environment in which the electrophoretic tank liquid operates is more suitable for the growth of microorganisms, which is easy to cause bacteria to grow in the running pipelines, pumps and valves, causing damage to the electrophoretic tank liquid and resulting in abnormal paint film.

[0003] As market demand increases, antibacterial surface treatment technology has gradually entered the public's field of vision. However, due to process limitations and other issues, in order to achieve antibacterial effects on the coating film, the previous electrophoretic process generally contained heavy metals such as lead and tin in the paint liquid. Later, due to environmental protection requirements, most electrophoretic paints do not contain these heavy metals. The current common method is to add fungicides, but there will be application problems such as difficult to control the quality of the coating film, easy to yellow and discolor, the yield rate cannot be guaranteed, and the antibacterial effect is not ideal.

[0004] Therefore, it is urgent to develop cathodic electrodeposition coatings with antibacterial properties to solve problems such as bath compatibility, durability of antibacterial effects, and overall performance of the coating. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art. The main body of the antibacterial emulsion resin is modified by introducing chloroxylenol to modify the small molecule epoxy resin, thereby improving the hardness of the main chain structure and increasing the antibacterial property of the resin. At the same time, an isocyanate curing agent modified by chloroxylenol is used to improve the overall synergistic antibacterial effect of the emulsion, and the emulsion does not contain heavy metals and is environmentally friendly.

[0006] Electrodeposition coatings are generally two-component. The bath liquid obtained by using antibacterial emulsion and HLS universal colorant has good antibacterial properties after circulation. The product has excellent storage stability, which improves the long-term antibacterial properties of the coating. At the same time, it maintains excellent mechanical properties and resistance to chemical media, meeting the application requirements of electrophoretic coatings in adverse environmental scenarios.

[0007] On the one hand, the present invention provides a cathode electrodeposition coating with antibacterial properties, wherein the coating is prepared from an antibacterial emulsion and a color paste in a weight ratio of 5:1, and the antibacterial emulsion includes a curing agent of a chloroxylenol-modified epoxy resin and a chloroxylenol-modified isocyanate.

[0008] In certain embodiments, the chloroxylenol-modified epoxy resin consists of the following components in parts by weight:

[0009]

[0010] In certain embodiments, the chloroxylenol-modified epoxy resin is prepared by the following preparation method:

[0011] Bisphenol A epoxy resin with an epoxy equivalent of 188, chloroxylenol, bisphenol A, bisphenol A polyoxyethylene ether, triphenylphosphine, and methyl isobutyl ketone are added into a four-necked flask, stirred for 10 minutes under nitrogen, heated to 140° C. and stirred for 1.5 hours. After reaching the specified epoxy equivalent, the temperature is lowered and propylene glycol monobutyl ether is added, and the temperature is further lowered to 100° C., diethanolamine is added, and the temperature is maintained at 120° C. for 2 hours, and the temperature is lowered to below 80° C. to obtain the chloroxylenol-modified epoxy resin.

[0012] In certain embodiments, the chloroxylenol-modified isocyanate curing agent consists of the following components in parts by weight:

[0013]

[0014] In certain embodiments, the chloroxylenol-modified isocyanate curing agent is prepared by the following preparation method:

[0015] Add methyl isobutyl ketone and MDI into a four-necked flask, pass nitrogen, heat up to 50°C, slowly add trimethylolpropane, maintain 50°C for 1 hour after addition, then maintain the temperature and slowly add chloroxylenol, maintain 50°C for 1 hour after addition, dropwise add a mixed solvent of ethylene glycol butyl ether and diethylene glycol butyl ether after the addition, heat up to 70°C for 2 hours, test NCO<1.5, cool to below 45°C and discharge to obtain the chloroxylenol modified isocyanate curing agent.

[0016] In certain embodiments, the coating comprises the following components: a chloroxylenol-modified epoxy resin, a chloroxylenol-modified isocyanate curing agent, an acidic neutralizing agent, and deionized water.

[0017] In certain embodiments, the acidic neutralizing agent is acetic acid, lactic acid, or a mixture of the two in any ratio.

[0018] On the other hand, the present invention provides a method for preparing a cathode electrodeposition coating having antibacterial properties, comprising the following steps:

[0019] Add chloroxylenol-modified epoxy resin and chloroxylenol-modified isocyanate curing agent into a reaction container and stir at 55-65°C for 1 hour to mix evenly. Add an acidic neutralizer and stir at 50-55°C for 1 hour. Then add deionized water into the reaction container at once and stir at high speed for 2 hours. After adding water, the temperature of the reaction container is controlled below 45°C.

[0020] Specifically, the chloroxylenol-modified epoxy resin is prepared by the following preparation method:

[0021] Bisphenol A epoxy resin with an epoxy equivalent of 188, chloroxylenol, bisphenol A, bisphenol A polyoxyethylene ether, triphenylphosphine, and methyl isobutyl ketone are added into a four-necked flask, stirred for 10 minutes under nitrogen, heated to 140° C. and stirred for 1.5 hours. After reaching the specified epoxy equivalent, the temperature is lowered and propylene glycol monobutyl ether is added, and the temperature is further lowered to 100° C., diethanolamine is added, and the temperature is maintained at 120° C. for 2 hours, and the temperature is lowered to below 80° C. to obtain the chloroxylenol-modified epoxy resin.

[0022] The chloroxylenol-modified isocyanate curing agent is prepared by the following preparation method:

[0023] Add methyl isobutyl ketone and MDI into a four-necked flask, pass nitrogen, heat up to 50°C, slowly add trimethylolpropane, maintain 50°C for 1 hour after addition, then maintain the temperature and slowly add chloroxylenol, maintain 50°C for 1 hour after addition, dropwise add a mixed solvent of ethylene glycol butyl ether and diethylene glycol butyl ether after the addition, heat up to 70°C for 2 hours, test NCO<1.5, cool to below 45°C and discharge to obtain the chloroxylenol modified isocyanate curing agent.

[0024] Beneficial effects: The present invention provides a cathode electrodeposition coating with antibacterial properties and a preparation method thereof. Chloroxylenol can penetrate the cell wall and cell membrane of microorganisms, and then react with the protein of bacteria or viruses, causing them to denature and inactivate. Chloroxylenol has a killing effect on most Gram-positive and Gram-negative bacteria, as well as fungi and molds, and has good broad-spectrum antibacterial properties. The resin body is modified by chain extension of small molecule epoxy resin by introducing chloroxylenol, which improves the hardness of the main chain structure and increases the antibacterial property of the resin. At the same time, the isocyanate curing agent modified by chloroxylenol is quoted, and the overall synergistic antibacterial effect of the emulsion is improved by adjusting the modification ratio and using the two in combination. Electrodeposition coatings are generally two-component. The tank liquid obtained by using an antibacterial emulsion and HLS universal color paste has good antibacterial properties after circulation, and the product has excellent storage stability, which improves the long-term antibacterial property of the coating, while maintaining excellent mechanical properties and chemical medium resistance, meeting the application of electrophoretic coatings in adverse environmental scenarios. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below through embodiments.

[0026] Example 1

[0027] Resin Example 1 Preparation of chloroxylenol-modified epoxy resin

[0028] The modified resin formula is as follows: 80 parts of bisphenol A epoxy resin, 4 parts of chloroxylenol, 30 parts of bisphenol A, 20 parts of bisphenol A polyoxyethylene ether, 0.05 parts of triphenylphosphine, 10 parts of methyl isobutyl ketone, 18 parts of propylene glycol monobutyl ether, and 10 parts of diethanolamine.

[0029] In a flask equipped with a stirrer, a condenser and a dropping funnel, add bisphenol A epoxy resin with an epoxy equivalent of 188, chloroxylenol, bisphenol A, bisphenol A polyoxyethylene ether, triphenylphosphine and methyl isobutyl ketone, stir for 10 minutes under nitrogen, heat to 140° C. and stir for 1.5 hours, and after reaching the specified epoxy equivalent (1100±100), cool down and add propylene glycol monobutyl ether, and continue to cool down to 100° C., add diethanolamine, maintain 120° C. for 2 hours, and cool down to below 80° C. to obtain the chloroxylenol-modified epoxy resin;

[0030] Resin Comparative Example 1 Preparation of General Epoxy Resin

[0031] The universal resin formula is as follows: 80 parts of bisphenol A epoxy resin, 33 parts of bisphenol A, 20 parts of bisphenol A polyoxyethylene ether, 0.05 parts of triphenylphosphine, 10 parts of methyl isobutyl ketone, 18 parts of propylene glycol monobutyl ether, and 10 parts of diethanolamine.

[0032] In a flask equipped with a stirrer, a condenser and a dropping funnel, add bisphenol A epoxy resin with an epoxy equivalent of 188, bisphenol A, bisphenol A polyoxyethylene ether, triphenylphosphine and methyl isobutyl ketone, stir under nitrogen for 10 minutes, heat to 140° C. and stir for 1.5 hours, and after reaching the specified epoxy equivalent (1100±100), cool down and add propylene glycol monobutyl ether, and continue to cool down to 100° C., add diethanolamine, maintain 120° C. for 2 hours, and cool down to below 80° C. to obtain the universal epoxy resin;

[0033] Curing Agent Example 1 Preparation of Chlorodimethylphenol Modified Isocyanate Curing Agent

[0034] The formula of chloroxylenol modified isocyanate curing agent is: 30 parts of methyl isobutyl ketone, 98 parts of MDI, 4.5 parts of trimethylolpropane, 8 parts of chloroxylenol, 60 parts of ethylene glycol butyl ether, and 35 parts of diethylene glycol butyl ether.

[0035] Add methyl isobutyl ketone and MDI into a four-necked flask, pass nitrogen, heat up to 50°C, slowly add trimethylolpropane, maintain 50°C for 1 hour after addition, then maintain the temperature and slowly add chloroxylenol, maintain 50°C for 1 hour after addition, dropwise add a mixed solvent of ethylene glycol butyl ether and diethylene glycol butyl ether after the addition, heat up to 70°C for 2 hours, test NCO<1.5, cool to below 45°C and discharge to obtain the chloroxylenol modified isocyanate curing agent.

[0036] Curing agent comparative example 1 preparation of universal isocyanate curing agent

[0037] The formula of universal isocyanate curing agent is: 30 parts of methyl isobutyl ketone, 98 parts of MDI, 4.5 parts of trimethylolpropane, 69 parts of ethylene glycol butyl ether, and 35 parts of diethylene glycol butyl ether.

[0038] Add methyl isobutyl ketone and MDI into a four-necked flask, pass nitrogen, heat up to 50°C, slowly add trimethylolpropane, maintain 50°C for 1 hour after adding, dropwise add a mixed solvent of ethylene glycol butyl ether and diethylene glycol butyl ether, heat up to 70°C for 2 hours after adding, test NCO<1.5, cool to below 45°C and discharge to obtain the universal isocyanate curing agent.

[0039] Preparation of antibacterial electrodeposition emulsion

[0040] Emulsion Example 1

[0041] Furthermore, the emulsion formula is: 36 parts of chloroxylenol-modified epoxy resin, 10 parts of chloroxylenol-modified isocyanate curing agent, 0.6 parts of acetic acid, and 61 parts of deionized water.

[0042] Add chlorodimethylol modified epoxy resin and chlorodimethylol isocyanate curing agent into a reaction container and stir at 55-65°C for 1 hour to mix evenly, add neutralizer, stir at 50-55°C for 1 hour, then add deionized water into the reaction container at once and stir at high speed for 2 hours. After adding water, the temperature of the reaction container is controlled below 45°C.

[0043] Emulsion Example 2

[0044] Furthermore, the emulsion formula is: 36 parts of chloroxylenol-modified epoxy resin, 10 parts of universal isocyanate curing agent, 0.6 parts of acetic acid, and 61 parts of deionized water.

[0045] Add chloroxylenol-modified epoxy resin and universal isocyanate curing agent into a reaction container and stir at 55-65°C for 1 hour to mix evenly, add neutralizer, stir at 50-55°C for 1 hour, then add deionized water into the reaction container at once and stir at high speed for 2 hours. After adding water, the temperature of the reaction container is controlled below 45°C.

[0046] Emulsion Example 3

[0047] Furthermore, the emulsion formula is: 36 parts of general epoxy resin, 10 parts of chloroxylenol-modified isocyanate curing agent, 0.6 parts of acetic acid, and 61 parts of deionized water.

[0048] Add universal epoxy resin and chloroxylenol modified isocyanate curing agent into a reaction container and stir at 55-65°C for 1 hour to mix evenly, add neutralizer, stir at 50-55°C for 1 hour, then add deionized water into the reaction container at once and stir at high speed for 2 hours. After adding water, control the temperature of the reaction container below 45°C.

[0049] Emulsion Example 4

[0050] Furthermore, the emulsion formula is: 36 parts of general epoxy resin, 10 parts of general isocyanate curing agent, 0.6 parts of acetic acid, and 61 parts of deionized water.

[0051] Add universal epoxy resin and universal isocyanate curing agent into a reaction container and stir at 55-65°C for 1 hour to mix evenly. Add neutralizer and stir at 50-55°C for 1 hour. Then add deionized water into the reaction container at once and stir at high speed for 2 hours. After adding water, the temperature of the reaction container is controlled below 45°C.

[0052] Emulsion Example 5

[0053] To the emulsion prepared in Emulsion Example 4, 0.5% chloroxylenol was added and stirred evenly.

[0054] Emulsion Example 6

[0055] The emulsion prepared in Emulsion Example 4 was added with 0.5% of the Kathon fungicide and stirred evenly.

[0056] The emulsions prepared from the above emulsion examples 1-6 were matched with HLS universal color paste at a ratio of 5:1 to prepare an electrophoresis tank liquid with a solid content of 12%, aged in the electrophoresis tank for 24 hours, and prepared with a sample plate (cold-rolled plate as the base material, the film thickness was controlled between 20-25um) under the conditions of electrophoresis voltage 150V, tank temperature 30°C, and electrophoresis time 60s, and the curing temperature was 180°C / 20min. The emulsions prepared from Examples 1-6 were subjected to stable heat storage, and a small amount of precipitation was uniformly produced at the bottom of Examples 5 and 6, indicating that the added bactericide had a certain negative impact on the stability of the emulsion. In addition, the hardness of the paint film of the emulsion prepared by using the epoxy resin modified with para-chlorodimethylphenol was improved to a certain extent compared with the scheme without para-chlorodimethylphenol modification, which was helpful for the application in the general industrial processing market.

[0057] The paint film / original paint test data are shown in the following table:

[0058]

[0059]

[0060] The emulsions prepared from the emulsion examples 1-6 are mixed with HLS universal color paste at a ratio of 5:1 to prepare an electrophoresis tank solution with a solid content of 12%. The same amount of mold and bacterial strains are added to each tank, and the electrophoresis tank solution is matured and tracked according to the tank parameters to test the MEQ value and pollution level of the tank solution. Reference for microbial content detection: Total colony count determination GB4789.2-2016. Detection conditions: bacteria, temperature 37°C, humidity greater than 90%; mold, temperature 28°C, humidity greater than 90%. Pollution level:

[0061] Level 0: Bacteria <10 (not detected), mold <10 (not detected)

[0062] Level 1+: 10< bacterial colonies <10 3 , 10<mold<10 2

[0063] Level 2++: 10 3 < Bacterial colonies <10 5 , 10 2 <Mold<10 3

[0064] Level 3+++: 10 5 < Bacterial colonies <10 7 , 10 3 <Mold<10 4

[0065] Level 4++++: 10 7 <Bacterial colonies, 10 4 <Mold

[0066] The comparison of bath liquid MEQ value and pollution level test is as follows

[0067]

[0068] Cathodic electrodeposition coating in electrophoresis production line is a special water-based coating, which is composed of organic resin, organic solvent, pigment filler, neutralizer, water and other substances. During use, the pH value and temperature of the bath liquid are maintained within a certain range. Water, organic matter, suitable pH value and temperature, these conditions provide a good basis for the growth of bacteria. Bacteria can reproduce in large quantities in the bath liquid by using these conditions, consume a large amount of organic matter in the reproduction process, destroy the organic composition in the bath liquid, make the composition of the bath liquid constantly change, demulsify, stratify, settle, reduce stability, and deteriorate film-forming properties. When the bacterial content is not high, these damages to the bath liquid are not obvious, but with the continuous reproduction of bacteria, the damage to the bath liquid is becoming more and more serious, among which the decrease in the MEQ value of the bath liquid is one of the more significant indicator changes. It can also be seen from the above table that the chemical modification scheme has a more significant long-term antibacterial property for the bath liquid, which is conducive to maintaining the cyclic antibacterial stability of the bath liquid. By modifying the resin and curing agent at the same time, it plays a synergistic antibacterial role and improves the stability of the overall application.

[0069] The present invention provides a cathode electrodeposition coating with antibacterial properties and a preparation method thereof. Chloroxylenol can penetrate the cell wall and cell membrane of microorganisms, and then react with the protein of bacteria or viruses, causing them to denature and inactivate. Chloroxylenol has a killing effect on most Gram-positive and Gram-negative bacteria, as well as fungi and molds, and has good broad-spectrum antibacterial properties. The resin body is modified by introducing chloroxylenol to extend the chain of small molecule epoxy resin, thereby improving the hardness of the main chain structure and increasing the antibacterial property of the resin. At the same time, the isocyanate curing agent modified by chloroxylenol is quoted, and the overall synergistic antibacterial effect of the emulsion is improved by adjusting the modification ratio and using the two in combination. Electrodeposition coatings are generally two-component. The tank liquid obtained by using an antibacterial emulsion with an HLS universal color paste has good antibacterial properties after circulation, and the product has excellent storage stability, which improves the long-term antibacterial property of the coating, while maintaining excellent mechanical properties and chemical medium resistance, meeting the application of electrophoretic coatings in scenes with poor environments.

[0070] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent substitutions or changes according to the technical solutions and novel concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A cathode electrodeposition coating having antibacterial properties, characterized in that: The coating is prepared from an antibacterial emulsion and a color paste in a weight ratio of 5:1, and the antibacterial emulsion includes a curing agent of a chloroxylenol-modified epoxy resin and a chloroxylenol-modified isocyanate.

2. The antibacterial cathode electrodeposition coating according to claim 1, characterized in that: The chloroxylenol-modified epoxy resin is composed of the following components in parts by weight:

3. The antibacterial cathode electrodeposition coating according to claim 2, characterized in that: The chloroxylenol-modified epoxy resin is prepared by the following preparation method: Bisphenol A epoxy resin with an epoxy equivalent of 188, chloroxylenol, bisphenol A, bisphenol A polyoxyethylene ether, triphenylphosphine, and methyl isobutyl ketone are added into a four-necked flask, stirred for 10 minutes under nitrogen, heated to 140° C. and stirred for 1.5 hours. After reaching the specified epoxy equivalent, the temperature is lowered and propylene glycol monobutyl ether is added, and the temperature is further lowered to 100° C., diethanolamine is added, and the temperature is maintained at 120° C. for 2 hours, and the temperature is lowered to below 80° C. to obtain the chloroxylenol-modified epoxy resin.

4. The antibacterial cathode electrodeposition coating according to claim 1, characterized in that: The chloroxylenol-modified isocyanate curing agent is composed of the following components in parts by weight:

5. The antibacterial cathode electrodeposition coating according to claim 4, characterized in that: The chloroxylenol-modified isocyanate curing agent is prepared by the following preparation method: Add methyl isobutyl ketone and MDI into a four-necked flask, pass nitrogen, heat up to 50°C, slowly add trimethylolpropane, maintain 50°C for 1 hour after addition, then maintain the temperature and slowly add chloroxylenol, maintain 50°C for 1 hour after addition, dropwise add a mixed solvent of ethylene glycol butyl ether and diethylene glycol butyl ether after the addition, heat up to 70°C for 2 hours, test NCO<1.5, cool to below 45°C and discharge to obtain the chloroxylenol modified isocyanate curing agent.

6. The antibacterial cathode electrodeposition coating according to claim 1, characterized in that: The coating comprises the following components: p-chloroxylenol modified epoxy resin, p-chloroxylenol modified isocyanate curing agent, acid neutralizing agent and deionized water.

7. The antibacterial cathode electrodeposition coating according to claim 6, characterized in that: The acidic neutralizer is acetic acid, lactic acid or a mixture of the two in any proportion.

8. A method for preparing the cathodic electrodeposition coating having antibacterial properties according to any one of claims 1 to 7, characterized in that: The following steps are involved: Add chloroxylenol-modified epoxy resin and chloroxylenol-modified isocyanate curing agent into a reaction container and stir at 55-65°C for 1 hour to mix evenly. Add an acidic neutralizer and stir at 50-55°C for 1 hour. Then add deionized water into the reaction container at once and stir at high speed for 2 hours. After adding water, the temperature of the reaction container is controlled below 45°C.

9. The method for preparing the antibacterial cathode electrodeposition coating according to claim 6, characterized in that: The chloroxylenol-modified epoxy resin is prepared by the following preparation method: Bisphenol A epoxy resin with an epoxy equivalent of 188, chloroxylenol, bisphenol A, bisphenol A polyoxyethylene ether, triphenylphosphine, and methyl isobutyl ketone are added into a four-necked flask, stirred for 10 minutes under nitrogen, heated to 140° C. and stirred for 1.5 hours. After reaching the specified epoxy equivalent, the temperature is lowered and propylene glycol monobutyl ether is added, and the temperature is further lowered to 100° C., diethanolamine is added, and the temperature is maintained at 120° C. for 2 hours, and the temperature is lowered to below 80° C. to obtain the chloroxylenol-modified epoxy resin.

10. The method for preparing the antibacterial cathode electrodeposition coating according to claim 6, characterized in that: The chloroxylenol-modified isocyanate curing agent is prepared by the following preparation method: Add methyl isobutyl ketone and MDI into a four-necked flask, pass nitrogen, heat up to 50°C, slowly add trimethylolpropane, maintain 50°C for 1 hour after addition, then maintain the temperature and slowly add chloroxylenol, maintain 50°C for 1 hour after addition, dropwise add a mixed solvent of ethylene glycol butyl ether and diethylene glycol butyl ether after the addition, heat up to 70°C for 2 hours, test NCO<1.5, cool to below 45°C and discharge to obtain the chloroxylenol modified isocyanate curing agent.

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