Antioxidant waterborne epoxy resin as well as preparation method and application thereof

Abstract

The invention discloses antioxidant waterborne epoxy resin as well as a preparation method and application thereof. The antioxidant waterborne epoxy resin is prepared from the following raw materials in parts by weight: 20-40 parts of deionized water, 40-60 parts of epoxy resin, 4-10 parts of a diluent, 5-10 parts of a reactive emulsifier, 1-3 parts of a wetting agent, 1-3 parts of an anti-yellowing agent, 0.5-1 part of an antioxidant, 0.5-1 part of a defoaming agent, 0.5-1 part of a pH value regulator, 0.3-1 part of an antibacterial agent, 0.2-1 part of a thickening agent and 5-15 parts of waterborne color ink. The anti-yellowing agent comprises aryl sulfonic acid and straight-chain alkanolamide. The anti-yellowing agent can remove residual phenol free radicals in epoxy resin, so that the anti-oxidation and anti-yellowing effects of phenol are achieved, and stable color and performance are kept; epoxy resin is emulsified by the reactive emulsifier, and a water-in-oil state in a system is converted into an oil-in-water state, so that no residual groups exist on the surface of the waterborne epoxy resin, and the possibility of oxidation yellowing is reduced.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, and particularly relates to an antioxidant waterborne epoxy resin, a preparation method thereof, and an application thereof. Background Art

[0002] Waterborne epoxy resins are widely used in fields such as coatings, adhesives, and composite materials. However, due to the presence of a bisphenol A structure in epoxy resins, they are easily interfered by external factors such as high temperature, and are prone to oxidation to form carbonyl groups, resulting in yellowing groups. Especially if they are exposed to sunlight for a long time, the phenomenon of oxidation and yellowing will be accelerated, which is extremely unsightly. Many epoxy resin system products with strict color requirements also put forward higher requirements for their antioxidant and yellowing resistance performance.

[0003] During the use of epoxy resins, they will be affected by various environmental factors, which may accelerate the oxidation process of epoxy resins. Usually, in order to increase the antioxidant property of plastic products, antioxidants are often added to the synthesis system. During the synthesis of epoxy resins, 2,6-di-tert-butyl-p-cresol (BHT) is often added as a phenolic antioxidant, which mainly plays an antioxidant role by capturing free radicals. To a certain extent, it can delay the oxidation process of epoxy resins. However, due to its limitations, as well as the interaction with other additives in epoxy resins and the influence of external factors, the epoxy resin still undergoes oxidation and yellowing; moreover, if there is still some residual BHT in the epoxy resin, when the epoxy resin forms a film, the free phenol will react with nitrogen oxides in the air to cause yellowing.

[0004] In order to completely solve the problem of yellowing of epoxy resins, existing patent technologies such as the invention patent with the publication number of CN104449283B propose an anti-aging coating, which mentions designing a two-component anti-aging coating in an oil-based system. However, the preparation process requires a vacuum condition, the process is relatively complex, and the two components need to be mixed during use to be cured, which is not convenient. Moreover, the oil-based system is not conducive to environmental protection and human health.

[0005] Alternatively, referring to a corrosion-resistant and anti-aging coating described in the patent document with the patent publication number CN115521701B, it pre-treats porous silica with a silane coupling agent and graphene oxide with glycerol triglycidyl ether; after reacting the pre-treated silica and pre-treated graphene oxide, it reacts with ethylenediamine and 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl chloride in sequence to obtain modified silica; it reacts isophorone diisocyanate and dimethylolbutyric acid to obtain a prepolymer, and reacts the prepolymer, polyethylene glycol and epoxy resin to obtain modified epoxy resin; triethylamine, pure water, modified silica and ethylenediamine are added to the modified epoxy resin in sequence and mixed and stirred to prepare a corrosion-resistant and anti-aging coating. A large number of pre-treatment steps are required, and the process requirements are strict, resulting in a relatively high cost.

[0006] In summary, there is an urgent need for a waterborne epoxy resin that can not only resist oxidation and discoloration at high temperatures but also has an environmentally friendly and simple process to expand its application scope. Summary of the Invention

[0007] The main object of the present invention is to provide an antioxidant waterborne epoxy resin, its preparation method and application, aiming to solve the technical problem that existing waterborne epoxy resins are prone to oxidation and discoloration.

[0008] To achieve the above object, in the first aspect of the present invention, an antioxidant waterborne epoxy resin is proposed, which is composed of the following raw materials in parts by weight: 20-40 parts of deionized water, 40-60 parts of epoxy resin, 4-10 parts of diluent, 5-10 parts of reactive emulsifier, 1-3 parts of wetting agent, 1-3 parts of anti-yellowing agent, 0.5-1 part of antioxidant, 0.5-1 part of defoaming agent, 0.5-1 part of pH regulator, 0.3-1 part of antibacterial agent, 0.2-1 part of thickener, 5-15 parts of water-based ink; wherein, the anti-yellowing agent includes aryl sulfonic acid and linear alkanolamide.

[0009] Further, the reactive emulsifier is one or more of phosphate ester surfactants, sulfate ester salts surfactants or polyether surfactants.

[0010] Further, the wetting agent is polysiloxane.

[0011] Further, the antioxidant is at least one of benzotriazole and acetylphenylhydrazine.

[0012] Further, the diluent is at least one of propylene glycol butyl ether, ethylene glycol butyl ether, polyethylene glycol 200 and propylene glycol ethylene glycol.

[0013] Further, the defoaming agent is silicone or mineral oil, the pH regulator is dimethylethanolamine; the antibacterial agent is isothiazolinone, and the thickener is non-ionic polyurethane.

[0014] On the other hand, the present invention provides a method for preparing an antioxidant waterborne epoxy resin for preparing the antioxidant waterborne epoxy resin, comprising the following steps:

[0015] S1: Modification stage: Add the epoxy resin, diluent, reactive emulsifier, wetting agent, anti-yellowing agent, antioxidant, and defoamer into the reaction kettle, and start stirring at a preset temperature and a preset stirring speed for 1-2 h to obtain a modified resin dispersion;

[0016] S2: Emulsification stage: Add the deionized water to the cooled modified resin dispersion, and start stirring and emulsifying for 1-2 h at the same time;

[0017] S3: Post-treatment stage: Add the pH regulator, antibacterial agent, and thickener, adjust the pH and viscosity, and then add the water-based color ink and stir evenly to obtain the antioxidant waterborne epoxy resin.

[0018] Further, in S1, the preset temperature is 75 °C and the preset stirring speed is 300 rpm.

[0019] Further, in S3, the pH is 7.5-8.5 and the viscosity is 1000-1500 mPa·s.

[0020] The present invention also provides the application of the above antioxidant waterborne epoxy resin in topcoats.

[0021] Beneficial effects:

[0022] An antioxidant waterborne epoxy resin, a preparation method and an application thereof according to the present invention. The antioxidant waterborne epoxy resin introduces an anti-yellowing agent prepared by compounding arylsulfonic acid and linear alkanolamide. This anti-yellowing agent belongs to a hindered phenol type anti-phenol yellowing agent, which can scavenge the residual phenolic free radicals in the epoxy resin, thereby achieving the effect of blocking phenolic antioxidant and anti-yellowing, and maintaining stable color and performance; and the antioxidant can effectively absorb ultraviolet rays and prevent the oxidation of the epoxy resin material by oxygen and other oxides to a certain extent; in the present invention, the epoxy resin in the water-based system is emulsified by a reactive emulsifier, converting the original water-in-oil state in the system into a water-in-oil state, with complete reaction, so that there are no residual groups on the surface of the waterborne epoxy resin, further reducing the possibility of oxidation and yellowing. The antioxidant waterborne epoxy resin of the present invention is a single-component system with water as the solvent, has simple preparation process requirements and low cost, and the content of organic compounds in the prepared product is limited, which is beneficial to environmental protection and human health. Description of the drawings

[0023] Figure 1 It is a state picture of the white topcoat of the antioxidant waterborne epoxy resin prepared in Examples 1-3 of the present invention after being maintained at 130 °C for 4 h;

[0024] Figure 2 Pictures of the states of the samples prepared in Comparative Examples 1 to 6 of the present invention after being maintained at 130 °C for 4 h.

[0025] Figure 3 Pictures of the chemical resistance tests of the samples prepared in Comparative Examples 1 to 3 and 6 of the present invention.

[0026] The realization, functional features, and advantages of the object of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed Embodiments

[0027] In the following embodiments of the present invention, the experimental methods without specific conditions noted are generally carried out under conventional conditions or according to the conditions recommended by the manufacturer. All common chemical reagents used in the embodiments are commercially available products.

[0028] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0029] The terms "comprising" and "having" and any variations thereof in the present invention are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps is not limited to the listed steps or modules, but optionally further includes steps not listed, or optionally further includes other steps inherent to these processes, methods, products, or devices.

[0030] To make the object, technical solution, and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the specific embodiments. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessarily confusing the concept of the present invention.

[0031] The following embodiments further describe the present invention, but the embodiments are not intended to limit the protection scope of the present invention.

[0032] An embodiment of the present invention provides an antioxidant waterborne epoxy resin, which is composed of the following raw materials in parts by weight: 20 - 40 parts of deionized water, 40 - 60 parts of epoxy resin, 4 - 10 parts of diluent, 5 - 10 parts of reactive emulsifier, 1 - 3 parts of wetting agent, 1 - 3 parts of anti-yellowing agent, 0.5 - 1 part of antioxidant, 0.5 - 1 part of defoaming agent, 0.5 - 1 part of pH regulator, 0.3 - 1 part of antibacterial agent, 0.2 - 1 part of thickener, and 5 - 15 parts of waterborne ink; wherein, the anti-yellowing agent includes arylsulfonic acid and linear alkanolamide.

[0033] In the above embodiments, the antioxidant waterborne epoxy resin is formulated with a yellowing inhibitor by introducing aryl sulfonic acid and linear alkanolamide. This yellowing inhibitor belongs to the hindered phenol type of anti-phenol yellowing agent, which can scavenge the residual phenolic free radicals in the epoxy resin, thereby achieving the effect of blocking phenol antioxidant and preventing yellowing, and maintaining stable color and properties. Moreover, the antioxidant can effectively absorb ultraviolet light and, to a certain extent, prevent the oxidation of the epoxy resin material by oxygen and other oxides. In the present invention, the epoxy resin in the waterborne system is emulsified by a reactive emulsifier, converting the original oil-in-water state in the system into a water-in-oil state. The reaction is complete, leaving no residual groups on the surface of the waterborne epoxy resin, further reducing the possibility of oxidation and yellowing.

[0034] The general structural formula of aryl sulfonic acid is Ar-SO3H, where Ar represents an aryl group. The aryl group can be a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group. Aryl sulfonic acid is acidic and can adjust the pH of the environment in the system. Maintaining a suitable acidic environment helps to inhibit chemical reactions that may cause yellowing. Moreover, the sulfonic acid group (-SO3H) in aryl sulfonic acid has a certain reactivity and can chemically combine or react with the chromophore group, thereby delaying the generation of yellowing structures.

[0035] Linear alkanolamide is a product formed by the reaction of a linear alkanol with a compound related to the amide group. Linear alkanolamide can capture free radicals and inhibit the progress of the oxidation chain reaction, converting free radicals into relatively stable products. The linear structure gives the molecule better linearity and extensibility, making it easier to interpenetrate and entangle with polymer segments, thus exhibiting better synergistic properties. Preferably, the yellowing inhibitor is formulated by compounding aryl sulfonic acid and linear alkanolamide. When compounded with aryl sulfonic acid, it can interact to form a physical barrier, reducing the damage of external factors to the internal structure and further maintaining the color stability.

[0036] In one embodiment, the reactive emulsifier is one or more of a phosphate ester type surfactant, a sulfate ester salt type surfactant, or a polyether type surfactant. A reactive emulsifier is a surfactant with a free radical polymerization functional group and is used as an emulsifier in emulsion polymerization. The phosphate ester type surfactant contains a phosphorus component, and the synthesized emulsion system has a rust prevention function. This phosphate ester type surfactant is preferably a mixture of monoester and diester. The diester contains two reactive groups, has stronger reactivity, and has a stronger emulsifying ability for the oil phase. The polyether type surfactant used in this embodiment is preferably a polyether epoxy emulsifier, which contains both a polyether alcohol hydrophilic structure and an epoxy hydrophobic structure and has a multi-branched macromolecular structure. When participating in epoxy curing, it can avoid the emulsifier from being free. When preparing an epoxy emulsion by inversion, it has the advantages of simple emulsification process, good emulsion stability, and excellent epoxy paint film performance.

[0037] In one embodiment, the wetting agent is polysiloxane. The siloxane chain in the molecular structure of polysiloxane has a low surface energy, which can quickly cover and spread on the surface of epoxy resin, reduce its surface tension, and improve the wetting ability of the liquid.

[0038] In one embodiment, the antioxidant is at least one of benzotriazole and acetylphenylhydrazine. Benzotriazole can absorb ultraviolet light, protect epoxy resin from being damaged by ultraviolet light, improve weather resistance, and benzotriazole can form complexes with metals, having good corrosion inhibition effects on metals such as copper, silver, and zinc, with good anti-corrosion effects; acetylphenylhydrazine can react with free radicals generated during the oxidation process, reducing the oxidation of epoxy resin by free radicals.

[0039] In one embodiment, the diluent is at least one of propylene glycol monobutyl ether, ethylene glycol monobutyl ether, polyethylene glycol 200, and propylene glycol ethylene glycol. The diluent has good solubility and a moderate evaporation rate, and can provide good construction performance during use.

[0040] In one embodiment, the defoaming agent is silicone or mineral oil, the pH regulator is dimethylethanolamine; the antibacterial agent is isothiazolinone, and the thickener is non-ionic polyurethane.

[0041] On the other hand, the present invention provides a preparation method of antioxidant waterborne epoxy resin for the antioxidant waterborne epoxy resin described in any one of the above embodiments, including the following steps:

[0042] S1: Modification stage: Add the epoxy resin, diluent, reactive emulsifier, wetting agent, anti-yellowing agent, antioxidant, and defoaming agent to the reaction kettle, and start stirring at a preset temperature and a preset stirring speed for 1 - 2 h to obtain a modified resin dispersion;

[0043] S2: Emulsification stage: Add the deionized water to the cooled modified resin dispersion, and start stirring and emulsifying for 1 - 2 h at the same time;

[0044] S3: Post-treatment stage: Add the pH regulator, antibacterial agent, and thickener, adjust the pH and viscosity, and then add water-based color ink, and stir evenly to obtain the antioxidant waterborne epoxy resin.

[0045] In this embodiment, first, at room temperature, the liquid epoxy resin, diluent, reactive emulsifier, wetting agent, anti-yellowing agent, antioxidant, and defoaming agent are mixed in the reaction kettle, and stirring is started and heating is carried out to uniformly mix the materials to obtain a modified epoxy resin dispersion.

[0046] In this embodiment, water is circulated around the modified epoxy resin dispersion for cooling until the temperature drops to 30 °C. Then, deionized water is slowly added while stirring, and the state of the epoxy resin dispersion is observed. Under the action of high-speed shearing, the whole system changes from water-in-oil to oil-in-water, forming a uniform and stable water-dilutable system. After the phase inversion of the resin dispersion, emulsification is maintained for 1-2 h.

[0047] In this embodiment, in the post-treatment stage, for the waterborne epoxy resin that is originally transparent, a pH regulator, an antibacterial agent, and a thickener are added to adjust the viscosity and pH value. Then, a waterborne color ink corresponding to the color of the topcoat to be prepared is added for color adjustment. For example, waterborne titanium white ink can be used to obtain an antioxidant waterborne epoxy resin white topcoat.

[0048] In the above embodiment, the preset temperature in S1 is 75 °C, and the preset stirring speed is 300 rpm.

[0049] In the above embodiment, the pH in S3 is 7.5-8.5, and the viscosity is 1000-1500 mPa·s. Within the range of 7.5-8.5 for the pH value, the epoxy resin system is relatively stable, and the chemical bonds in its internal structure are not easily hydrolyzed or undergo other chemical reactions in an environment close to neutral. The antioxidant waterborne epoxy resin with a viscosity within 1000-1500 mPa·s is more convenient for construction, has better leveling property, and is more beautiful after curing and forming.

[0050] The present invention also provides an application of the antioxidant waterborne epoxy resin according to any one of the above embodiments in a topcoat.

[0051] Specific embodiments are as follows:

[0052] In the following embodiments, all raw materials used in the experiments are commercially available. For the specific purchasing manufacturers, please refer to Table 1.

[0053] Table 1. Raw material purchasing manufacturers

[0054]

[0055] Example 1

[0056] (1) Formulation: Epoxy resin (E-44 35 wt%, E-51 10 wt%), diluent (propylene glycol butyl ether) 5 wt%, reactive emulsifier (phosphate ester surfactant 6 wt%, sulfate ester surfactant 2 wt%), wetting agent (polysiloxane) 1 wt%, anti-yellowing agent 2.5 wt%, antioxidant (benzotriazole) 0.5 wt%, defoaming agent (mineral oil) 0.5 wt%, pH regulator (dimethyl ethanolamine) 0.5 wt%, antibacterial agent (isothiazolinone) 0.3 wt%, thickener (non-ionic polyurethane) 0.5 wt%, deionized water 36.2 wt%.

[0057] (2) Preparation steps:

[0058] S1: Modification stage: Add epoxy resin, diluent, reactive emulsifier, wetting agent, anti-yellowing agent, antioxidant, and defoamer into the reaction kettle according to the above formula amounts. Stir the mixture at a speed of 300 rpm at room temperature for 20 minutes, then heat it up to 70°C and maintain a constant temperature and speed. After 1 h, a modified resin dispersion is obtained.

[0059] S2: Emulsification stage: Cool the modified dispersion to 30°C with cooling water and maintain it. Increase the speed to 800 rpm, add all the deionized water required by the formula. When adding water, increase the rate gradually from 2 mL / min to 30 mL / min until all the required water consumption is added. After the resin dispersion is phase-inverted, reduce the speed to 500 rpm. The total emulsification phase inversion stabilization time is 1 h.

[0060] S3: Post-treatment stage: Add the pH regulator in the formula amount to adjust the pH value of the product within the range of 7.5 - 8.5. Then add the antibacterial agent and thickener to adjust the viscosity of the product to 1000 - 1500 mPa·s. Add water-based titanium white ink at a speed of 300 rpm and stir for 30 minutes. After sampling and testing that the fineness is qualified, filter and discharge to obtain an antioxidant water-based epoxy resin white topcoat.

[0061] Example 2

[0062] (1) Formula: Epoxy resin (E-44 25 wt%, E-51 20 wt%), diluent (ethylene glycol monobutyl ether) 5 wt%, reactive emulsifier (phosphate ester surfactant 5 wt%, sulfate ester surfactant 4 wt%), wetting agent (polysiloxane) 1 wt%, anti-yellowing agent 1.5 wt%, antioxidant (benzotriazole) 0.5 wt%, defoamer (mineral oil) 0.5 wt%, pH regulator (dimethyl ethanolamine) 0.5 wt%, antibacterial agent (isothiazolinone) 0.3 wt%, thickener (non-ionic polyurethane) 0.5 wt%, deionized water 36.2 wt%.

[0063] (2) The preparation method is the same as that of Example 1.

[0064] Example 3

[0065] (1) Formulation: Epoxy resin (E-44 35wt%, E-51 10wt%), diluent (propylene glycol butyl ether) 5wt%, reactive emulsifier (phosphate surfactant 5wt%, polyether surfactant 2.5wt%), wetting agent (polysiloxane) 1wt%, anti-yellowing agent 3wt%, antioxidant (acetylphenylhydrazine) 0.5wt%, defoamer (silicone) 0.5wt%, pH regulator (dimethyl ethanolamine) 0.5wt%, antibacterial agent (isothiazolinone) 0.3wt%, thickener (nonionic polyurethane) 0.5wt%, deionized water 36.2wt%.

[0066] (2) The preparation method is the same as that of Example 1.

[0067] Comparative Example 1

[0068] The difference between this comparative example and Example 1 is only that: the anti-yellowing agent in the formulation is adjusted to 0.5wt%, and the other components and preparation method are the same as those of Example 1.

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 1 is only that: the anti-yellowing agent in the formulation is adjusted to 3.5wt%, and the other components and preparation method are the same as those of Example 1.

[0071] Comparative Example 3

[0072] The difference between this comparative example and Example 1 is only that: S1: The preset temperature in the modification stage is 50°C, and the other components and preparation method are the same as those of Example 1.

[0073] Comparative Example 4

[0074] The difference between this comparative example and Example 1 is only that: S1: The modification time in the modification stage is 2h, and the other components and preparation method are the same as those of Example 1.

[0075] Comparative Example 5

[0076] (1) Formulation: Epoxy resin (E-44 35wt%, E-51 10wt%), diluent (propylene glycol butyl ether) 5wt%, reactive emulsifier (phosphate surfactant 6wt%, sulfate surfactant 2wt%), wetting agent (polysiloxane) 1wt%, antioxidant (benzotriazole) 3.0wt%, defoamer (mineral oil) 0.5wt%, pH regulator (dimethyl ethanolamine) 0.5wt%, antibacterial agent (isothiazolinone) 0.3wt%, thickener (nonionic polyurethane) 0.5wt%, deionized water 36.2wt%.

[0077] (2) The difference between this comparative example and Example 1 is only that: no anti-yellowing agent is added, and the anti-yellowing agent is replaced by an antioxidant, and other components and preparation methods are the same as those in Example 1.

[0078] Comparative Example 6

[0079] (1) Formula: Epoxy resin (E-44 35wt%, E-51 10wt%), diluent (propylene glycol butyl ether) 5wt%, wetting agent (polysiloxane) 1wt%, anti-yellowing agent 2.5wt%, antioxidant (benzotriazole) 0.5wt%, defoaming agent (mineral oil) 0.5wt%, pH regulator (dimethyl ethanolamine) 0.5wt%, antibacterial agent (isothiazolinone) 0.3wt%, thickener (non-ionic polyurethane) 0.5wt%, deionized water 44.2wt%.

[0080] (2) Preparation steps:

[0081] S1: Modification stage: Add epoxy resin, diluent, wetting agent, anti-yellowing agent, antioxidant, and defoaming agent to the reaction kettle according to the above formula amount, stir the mixture at a speed of 300 rpm at room temperature for 20 minutes, then heat up to 70°C and maintain a constant temperature and speed. After 1 h, a modified resin dispersion is obtained.

[0082] S2: Emulsification stage: Cool the modified dispersion to 30°C with cooling water and maintain it, increase the speed to 800 rpm, add all the deionized water required in the formula, and gradually increase the water addition rate from 2 mL / min to 30 mL / min until all the required water consumption is added. Then reduce the speed to 500 rpm, and the whole emulsification inversion stabilization time is 1 h.

[0083] S3: Post-treatment stage: Add the pH regulator in the formula amount, adjust the pH value of the product within the range of 7.5 - 8.5, then add the antibacterial agent and thickener, adjust the viscosity of the product to 1000 - 1500 mPa·s, add water-based titanium white ink at a speed of 300 rpm, stir for 30 minutes, filter and discharge to obtain the sample.

[0084] The difference between this comparative example and Example 1 is only that: no reactive emulsifier is added, and it is replaced by a common non-reactive emulsifier OP-10, and other components and preparation methods are the same as those in Example 1.

[0085] For the antioxidant waterborne epoxy resin white topcoats prepared in the above Examples 1 - 3 and the samples prepared in Comparative Examples 1 - 6, add Huntsman curing agent 38-1 and cure at room temperature for 72 h before testing. The testing is carried out according to the following steps:

[0086] High-temperature resistance test: 1. Spray the film with a spray gun to make the film thickness within the range of 25 - 30 μm; 2. Dry and cure at room temperature for 7 days; 3. Dry bake at 135 °C for 4 h; 4. Compare the discoloration situation.

[0087] Chemical resistance test: Detect according to GB / T 9265 - 2009.

[0088] Adhesion test: Detect according to GB / T 9286 - 1998.

[0089] Impact resistance test: Detect according to GB / T 1732 - 2020.

[0090] The test results are shown in Tables 2 - 3 below.

[0091] Table 2. Data of the examples

[0092]

[0093] Table 3. Data of the comparative examples

[0094]

[0095] From Tables 2 and 3, and Figures 1 to 3 it can be seen that after the antioxidant waterborne epoxy resin white topcoat prepared in Examples 1 - 3 is cured, even when placed at 130 °C for 4 h, it can maintain a stable color, and other necessary properties as a coating are also superior; in Comparative Example 1, due to the small amount of anti-yellowing agent added, the surface is still oxidized and yellowed after the high-temperature resistance test; in contrast, in Comparative Example 2 with a larger amount of anti-yellowing agent added, although there is no discoloration, there is slight peeling during the adhesion test; in Comparative Examples 3 and 4, the change in the modification temperature or modification time causes the reaction not to proceed fully, resulting in the phenomena of acid dripping and whitening and the appearance of microbubbles; in Comparative Example 5, using an antioxidant instead of the anti-yellowing agent of the present application shows a situation of not being resistant to high temperature and serious yellowing, proving that the phenolic free radicals with strong surface reaction activity of the sample are not completely removed; in Comparative Example 6, using a common emulsifier, it may be that there are still reactive groups remaining on the surface of the sample, resulting in a large number of bubbles after acid dripping, and both the chemical resistance and adhesion are poor.

[0096] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. An antioxidant waterborne epoxy resin, characterized in that, It is composed of the following raw materials in parts by weight: 20-40 parts of deionized water, 40-60 parts of epoxy resin, 4-10 parts of diluent, 5-10 parts of reactive emulsifier, 1-3 parts of wetting agent, 1-3 parts of anti-yellowing agent, 0.5-1 part of antioxidant, 0.5-1 part of defoamer, 0.5-1 part of pH regulator, 0.3-1 part of antibacterial agent, 0.2-1 part of thickener, and 5-15 parts of water-based color ink; wherein, the anti-yellowing agent includes aryl sulfonic acid and linear alkanolamide.

2. The antioxidant waterborne epoxy resin according to claim 1, characterized in that, The reactive emulsifier is one or more of phosphate ester surfactants, sulfate ester salts surfactants or polyether surfactants.

3. The antioxidant waterborne epoxy resin according to claim 1, characterized in that The wetting agent is polysiloxane.

4. The antioxidant waterborne epoxy resin according to claim 1, wherein The antioxidant is at least one of benzotriazole and acetylphenylhydrazine.

5. The antioxidant waterborne epoxy resin according to claim 1, wherein The diluent is at least one of propylene glycol monobutyl ether, ethylene glycol monobutyl ether, polyethylene glycol 200, and propylene glycol ethylene glycol.

6. The antioxidant waterborne epoxy resin according to claim 1, wherein The defoamer is silicone or mineral oil; the pH regulator is dimethylethanolamine; the antibacterial agent is isothiazolinone, and the thickener is non-ionic polyurethane.

7. A method for preparing the antioxidant waterborne epoxy resin according to any one of claims 1 to 6, characterized in that, It includes the following steps: S1: Modification stage: Add the epoxy resin, diluent, reactive emulsifier, wetting agent, anti-yellowing agent, antioxidant, and defoamer into the reaction kettle, start stirring at a preset temperature and a preset stirring speed, and obtain a modified resin dispersion after 1 h. S2: Emulsification stage: Add the deionized water to the cooled modified resin dispersion, and start stirring and emulsifying for 1-2 h at the same time. S3: Post-treatment stage: Add the pH regulator, antibacterial agent, and thickener, adjust the pH and viscosity, then add the water-based color ink, and stir evenly to obtain the antioxidant water-based epoxy resin.

8. The preparation method of the antioxidant waterborne epoxy resin according to claim 7, characterized in that, The preset temperature in S1 is 75 °C, and the preset stirring speed is 300 rpm.

9. The preparation method of the antioxidant waterborne epoxy resin according to claim 7, characterized in that, The pH in S3 is 7.5-8.5, and the viscosity is 1000-1500 mPa·s.

10. Application of the antioxidant water-based epoxy resin according to any one of claims 1-6 in topcoat.

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