Weather-resistant water-based epoxy resin paint and method for preparing the same

Abstract

The application discloses a weather-resistant water-based epoxy resin paint and a preparation method thereof, and the paint comprises a complex system solvent of a light stabilizer containing a hindered amine light stabilizer and an ultraviolet absorber, and the stability of the light stabilizer in the paint is improved. The hindered amine light stabilizer provides a modified bis-2,2,6,6-tetramethylpiperidyl octanedioate, and the weather resistance of the bis-2,2,6,6-tetramethylpiperidyl octanedioate is more excellent, normal octane used in synthesis can be recycled after distillation, production cost is low, and pollution is avoided. Therefore, the water-based epoxy resin paint maintains original physical properties, meanwhile, a color difference value and a light loss rate are reduced, and weather resistance is greatly improved.

Description

Technical Field

[0001] This application belongs to the field of epoxy coating technology, specifically relating to a weather-resistant waterborne epoxy resin coating and its preparation method. Background Technology

[0002] Epoxy resins are polymers with excellent mechanical properties, high stability, and good adhesion, and are therefore widely used in the coatings industry. However, epoxy resin coatings commonly suffer from problems such as yellowing, loss of gloss, and decreased mechanical strength due to photoaging. This is because the epoxy chains in epoxy resins are easily broken under ultraviolet radiation, ultimately leading to damage to the substrate.

[0003] Adding light stabilizers to coatings is one of the simplest and most effective methods. Light stabilizers are mainly classified into four categories based on their mechanisms of action: hindered amine light stabilizers, UV absorbers, light shielding agents, and quenchers. Among these, hindered amine light stabilizers exhibit superior weather resistance compared to other types and have good compatibility with resins, making them the most widely used in coatings. CN105504920A discloses an acrylic resin coating with added Tinuvin 292, which improves the coating's resistance to light aging and provides good heat reflection. However, with increasing demands for material performance, single light stabilizers are no longer sufficient to meet current needs, and more and more research is focusing on synergistic light stabilizer formulations. CN101845263B discloses a UV-curable weather-resistant coating that, in addition to common coating components, includes a compounded light stabilizer consisting of salicylic acid-based light stabilizers, hindered amine-based light stabilizers, and benzotriazole-based light stabilizers. This approach maintains the basic properties of the coating while overcoming the existing problem of poor weather resistance. However, the salicylic acid light stabilizers have disadvantages such as low melting point, easy volatility, and easy discoloration under strong light, which have a certain impact on the performance of the compound system. Summary of the Invention

[0004] This application provides a weather-resistant waterborne epoxy resin coating and its preparation method to solve the above-mentioned technical problems.

[0005] To solve the above-mentioned technical problems, one technical solution adopted in this application is: a weather-resistant waterborne epoxy resin coating, which, by weight, is composed of the following components: 1 part of a compound solvent containing a hindered amine light stabilizer and a UV absorber, 1-10 parts of an organic solvent, and 20-200 parts of a waterborne epoxy resin emulsion.

[0006] Furthermore, the hindered amine light stabilizer is one of bis-2,2,6,6-tetramethylpiperidinol sebacate and modified bis-2,2,6,6-tetramethylpiperidinol sebacate.

[0007] Furthermore, the ultraviolet absorber is one of 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2-[2-hydroxy-5-tert-octylphenyl]benzotriazole.

[0008] Furthermore, the mass ratio of hindered amine light stabilizer to ultraviolet absorber is 1:2 to 2:1.

[0009] Furthermore, the organic solvent is one of ethanol, acetone, toluene, xylene, and ethylene glycol monobutyl ether.

[0010] Furthermore, the mass ratio of each component in the waterborne epoxy resin emulsion is as follows: 20% epoxy amine resin, 3% auxiliary resin, 11% blocked isocyanate curing agent, 2% organic solvent, 1% surfactant, 1.5% leveling agent, 0.5% organic acid, 0.5% dispersant, 0.5% anti-settling agent, and 60% deionized water.

[0011] Furthermore, the dispersant is one of the following as its main components: nonionic wetting and dispersing agent, controlled free radical type superdispersant, and polymeric superdispersant.

[0012] Furthermore, the anti-settling agent is one of the following: inorganic salt anti-settling agent, organic anti-settling agent, and surfactant anti-settling agent.

[0013] One technical solution adopted in this application is: a method for preparing a weather-resistant waterborne epoxy resin coating, comprising the following steps:

[0014] A first solution is obtained by dissolving a light stabilizer compound containing a hindered amine light stabilizer and a UV absorber in an organic solvent.

[0015] The first solution is added to the aqueous epoxy resin emulsion, and then deionized water is added to prepare the bath solution;

[0016] The bath solution was heated to 32°C and electroplated onto an iron plate at a voltage of 180V for 60 seconds. The plate was then baked at 180°C for 20 minutes to obtain a transparent paint film and a weather-resistant waterborne epoxy resin coating.

[0017] A method for preparing modified sebacic acid bis-2,2,6,6-tetramethylpiperidinol ester includes the following steps: dissolving 5g of sebacic acid bis-2,2,6,6-tetramethylpiperidinol ester and 0.5g of molybdenum trioxide in 20.7g of n-octane, heating to 125℃, slowly adding 9.21g of 70% tert-butyl hydroperoxide, reacting for 12h, filtering, and distilling under reduced pressure at 55℃ to obtain modified sebacic acid bis-2,2,6,6-tetramethylpiperidinol ester.

[0018] The beneficial effects of this application are as follows: The design of this application includes a light stabilizer compound system, comprising a hindered amine light stabilizer and a UV absorber, which improves the stability of the light stabilizer in the coating. The hindered amine light stabilizer provides a modified 770, which exhibits superior weather resistance compared to Tinuvin 770 (bis-2,2,6,6-tetramethylpiperidinol sebacate). The n-octane used in the synthesis can be distilled and recycled, resulting in low production costs and no pollution. Therefore, the waterborne epoxy resin coating of this application maintains its original physical properties while reducing its color difference and gloss loss rate, and significantly improving its weather resistance. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments.

[0020] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0021] This application provides a weather-resistant waterborne epoxy resin coating, which, by weight, comprises the following components: 1 part of a compound solvent containing a hindered amine light stabilizer and a UV absorber, 1-10 parts of an organic solvent, and 20-200 parts of a waterborne epoxy resin emulsion. The mass ratio of the hindered amine light stabilizer to the UV absorber is 1:2 to 2:1.

[0022] This application provides a method for preparing the above-mentioned weather-resistant waterborne epoxy resin coating, including the following steps:

[0023] S1. Dissolve a light stabilizer compound containing a hindered amine light stabilizer and a UV absorber in an organic solvent to obtain a first solution.

[0024] In this embodiment, the hindered amine light stabilizer is one of bis-2,2,6,6-tetramethylpiperidinol sebacate (Tinuvin 770) and modified bis-2,2,6,6-tetramethylpiperidinol sebacate (modified 770). The ultraviolet absorber is one of 2-hydroxy-4-n-octyloxybenzophenone (UV531), 2-hydroxy-4-methoxybenzophenone (UV-9), and 2-[2-hydroxy-5-tert-octylphenyl]benzotriazole (UV329). The organic solvent is one of ethanol, acetone, toluene, xylene, and ethylene glycol monobutyl ether.

[0025] S2. Add the first solution to the aqueous epoxy resin emulsion, and then add deionized water to prepare the bath solution.

[0026] S3. Heat the bath to 32°C and electroplate it onto the iron plate at a voltage of 180V for 60 seconds. Then bake it at 180°C for 20 minutes to prepare a transparent paint film and obtain a weather-resistant waterborne epoxy resin coating.

[0027] In this embodiment, the mass ratio of the components of the aqueous epoxy resin emulsion is as follows: 20% epoxy amine resin, 3% auxiliary resin, 11% blocked isocyanate curing agent, 2% organic solvent, 1% surfactant, 1.5% leveling agent, 0.5% organic acid, 0.5% dispersant, 0.5% anti-settling agent, and 60% deionized water. The dispersant is one of the following: a nonionic wetting and dispersing agent, a controlled free radical hyperdispersant, or a polymeric hyperdispersant. The anti-settling agent is one of the following: an inorganic salt anti-settling agent, an organic anti-settling agent, or a surfactant anti-settling agent.

[0028] This application provides a method for preparing the above-mentioned modified sebacic acid bis-2,2,6,6-tetramethylpiperidinol ester (modified 770), comprising the following steps:

[0029] 5g of bis-2,2,6,6-tetramethylpiperidinol sebacate and 0.5g of molybdenum trioxide were dissolved in 20.7g of n-octane, heated to 125℃, and 9.21g of 70% tert-butyl hydroperoxide was slowly added dropwise. After reacting for 12h, the mixture was filtered and distilled under reduced pressure at 55℃ to obtain modified 770.

[0030] Example 1

[0031] The compound system containing 3g of modified 770 and 3g of UV531 was dissolved in 15g of ethylene glycol monobutyl ether and added to 300g of waterborne epoxy resin emulsion. The bath solution was heated to 32℃ and electroplated onto an iron plate at 180V for 60s. The plate was then baked at 180℃ for 20min to obtain sample 1.

[0032] Example 2

[0033] The compound system containing 2g of modified 770 and 4g of UV-9 was dissolved in 6g of toluene and added to 300g of waterborne epoxy resin emulsion. The bath solution was heated to 32℃ and electroplated onto an iron plate at 180V for 60s. The plate was then baked at 180℃ for 20min to obtain sample 2.

[0034] Example 3

[0035] The compound system containing 4g of modified 770 and 2g of UV329 was dissolved in 30g of ethanol and added to 300g of water-based epoxy resin emulsion. The bath solution was heated to 32℃ and electroplated onto an iron plate at 180V for 60s. The plate was then baked at 180℃ for 20min to obtain sample 3.

[0036] Example 4

[0037] The compound system containing 2g Tinuvin 770 and 4g UV531 was dissolved in 6g xylene and added to 300g of waterborne epoxy resin emulsion. The bath solution was heated to 32℃ and electroplated onto an iron plate at 180V for 60s. The plate was then baked at 180℃ for 20min to obtain sample 4.

[0038] Example 5

[0039] The compound system containing 3g Tinuvin 770 and 3g UV-9 was dissolved in 30g ethylene glycol monobutyl ether and added to 300g waterborne epoxy resin emulsion. The bath solution was heated to 32℃ and electroplated onto an iron plate at 180V for 60s. The plate was then baked at 180℃ for 20min to obtain sample 5.

[0040] Example 6

[0041] The compound system containing 3g Tinuvin 770 and 3g UV329 was dissolved in 15g ethanol and added to 300g waterborne epoxy resin emulsion. The bath solution was heated to 32℃ and electroplated onto an iron plate at 180V for 60s. The plate was then baked at 180℃ for 20min to obtain sample 6.

[0042] Comparative Example 1

[0043] 300g of waterborne epoxy resin emulsion was stirred with 500g of deionized water at room temperature for 24h, heated to 32℃, electroplated onto an iron plate at 180℃ for 60s, and baked at 180℃ for 20min to obtain sample 7.

[0044] This application provides a sedimentation resistance test: add emulsion and deionized water to a disposable transparent cup in a certain mass ratio, stir well, cover and let stand for 24 hours, and then observe whether there is sedimentation in the cup and whether there are hard lumps in the sedimentation.

[0045] The samples in the examples were tested for coating hardness according to the national standard GB / T6739-1996 "Coating Hardness - Pencil Hardness Test Method".

[0046] Adhesion test: The adhesion of the paint film was tested using the cross-cut adhesion test according to GB / T9286-1998 "Cross-cut test for paint and varnish films". Color difference value and gloss loss test: The aging rating method for paint and varnish coatings was performed according to GB / T1766.

[0047] Table 1 Comparison of anti-settling properties and stratification tests between each embodiment and the comparative example.

[0048]

[0049] As shown in Table 1, Examples 1-3, 5, and the comparative examples all exhibited good anti-precipitation and dispersibility. Example 4 showed slight precipitation due to the presence of the benzophenone-based light stabilizer UV531 in the compound system. Examples 1 and 6 showed slight stratification because UV329 in the compound system had low solubility in both water and ethanol, thus affecting the dispersibility of the compound system in the emulsion. The compound system used in this patent exhibited the same anti-precipitation and stratification properties as the original emulsion, maintaining the original performance of the emulsion.

[0050] Table 2 Comparison of pen hardness and adhesion tests between the various embodiments and the comparative examples.

[0051]

[0052] As can be seen from Table 2, the pencils in Examples 1-6 and the comparative example have the same hardness and adhesion, indicating that the addition of light stabilizer has no effect on the physical properties of the coating.

[0053] Table 3 Comparison of color difference and gloss test results between each embodiment and the comparative example.

[0054]

[0055]

[0056] As shown in Table 3, the color difference and gloss loss of the waterborne epoxy resin coatings in Examples 1-6, which have added light stabilizers, are significantly lower than those in the comparative examples, indicating that the light stabilizers greatly improve the weather resistance of the epoxy resin coatings. Furthermore, comparing Examples 1-6, it can be seen that Example 1 has the lowest color difference value (1.81) and gloss loss rate (6.17), meaning that Example 1 exhibits superior weather resistance.

[0057] In summary, this application presents a light stabilizer compound system comprising a hindered amine light stabilizer and a UV absorber, thereby improving the stability of the light stabilizer in the coating. The hindered amine light stabilizer provides a modified 770, exhibiting superior weather resistance compared to Tinuvin 770 (bis-2,2,6,6-tetramethylpiperidinol sebacate). The n-octane used in the synthesis can be distilled and recycled, resulting in low production costs and no pollution. Therefore, the waterborne epoxy resin coating of this application maintains its original physical properties while reducing color difference and gloss loss, significantly improving weather resistance.

[0058] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A weather-resistant waterborne epoxy resin coating, characterized in that, The product, by weight, comprises the following components: 1 part of a compound solvent containing a hindered amine light stabilizer and a UV absorber, 1-10 parts of an organic solvent, and 20-200 parts of an aqueous epoxy resin emulsion; the mass ratio of each component in the aqueous epoxy resin emulsion is: 20% epoxy amine resin, 3% auxiliary resin, 11% blocked isocyanate curing agent, 2% organic solvent, 1% surfactant, 1.5% leveling agent, 0.5% organic acid, 0.5% dispersant, 0.5% anti-settling agent, and 60% deionized water; wherein the hindered amine light stabilizer is a modified sebacic acid bis-2,2,6,6-tetramethylpiperidinol ester; the preparation method of the modified sebacic acid bis-2,2,6,6-tetramethylpiperidinol ester includes the following steps: dissolving 5 g of sebacic acid bis-2,2,6,6-tetramethylpiperidinol ester and 0.5 g of molybdenum trioxide in 20.7 g of water. In 1 g of n-octane, the temperature was raised to 125 °C, and 9.21 g of 70% tert-butyl hydrogen peroxide was slowly added dropwise. After reacting for 12 h, the mixture was filtered and distilled under reduced pressure at 55 °C to obtain the modified sebacic acid bis-2,2,6,6-tetramethylpiperidinol ester.

2. The weather-resistant waterborne epoxy resin coating according to claim 1, characterized in that, The ultraviolet absorber is one of 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2-[2-hydroxy-5-tert-octylphenyl]benzotriazole.

3. The weather-resistant waterborne epoxy resin coating according to claim 1, characterized in that, The mass ratio of the hindered amine light stabilizer to the ultraviolet absorber is 1:2 to 2:

1.

4. The weather-resistant waterborne epoxy resin coating according to claim 1, characterized in that, The organic solvent is one of ethanol, acetone, toluene, xylene, and ethylene glycol monobutyl ether.

5. The weather-resistant waterborne epoxy resin coating according to claim 1, characterized in that, The dispersant is one of the following: a nonionic wetting and dispersing agent and a polymeric superdispersant.

6. The weather-resistant waterborne epoxy resin coating according to claim 1, characterized in that, The anti-settling agent is one of the following: inorganic salt anti-settling agent, organic anti-settling agent, and surfactant anti-settling agent.

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