A waterborne abrasion-resistant epoxy coating and a method for preparing the same

Abstract

The application relates to the field of coatings, and particularly discloses a water-based wear-resistant epoxy coating and a preparation method thereof, which comprises the following raw materials: a water-based epoxy resin, a water-based curing agent, a dispersing agent, a defoaming agent, a leveling agent, water and a core-shell filler, wherein the core-shell filler takes nanometer silicon dioxide as a core material, and a polydopamine shell layer is generated in situ from dopamine hydrochloride in an alkaline buffer solution; the preparation method comprises the following steps: mixing the water-based epoxy resin, the dispersing agent and part of the water, and dispersing to form a base; then, the core-shell filler is added, stirring is carried out, the defoaming agent and the leveling agent and the remaining water are added, and stirring is carried out; after cooling, the water-based curing agent is added, stirring and standing are carried out, and the water-based wear-resistant epoxy coating is prepared. The application has the characteristics that the prepared water-based epoxy coating has better wear resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of paint, more particularly, it relates to a water-based wear-resistant epoxy paint and a preparation method thereof. BACKGROUND

[0002] Epoxy paint is widely used in industrial corrosion protection, floor, mechanical protection and other fields due to its excellent adhesion, chemical resistance and mechanical strength. However, traditional solvent-based epoxy paint has the problem of poor environmental protection. Solvent-based epoxy resin contains a large amount of organic solvent, and the emission of volatile organic compounds (VOC) is high.

[0003] Water-based epoxy paint uses water as the dispersion medium, and the VOC content can be reduced to 50 g / L, becoming the environmental protection alternative direction. However, the wear resistance, hardness and corrosion resistance of water-based epoxy paint are still significantly lower than those of solvent-based products. The main reasons are as follows: the molecular weight of water-based epoxy resin is low, and the crosslinking density after film formation is insufficient, resulting in poor compactness of the coating, which is easily scratched by hard particles, and the wear resistance is only 30-50% of that of solvent-based paint; secondly, traditional wear-resistant fillers such as silicon dioxide are easy to agglomerate in water-based system due to the difference in surface polarity, forming stress concentration points and reducing the performance of the paint.

[0004] With the rapid development of emerging industries such as intelligent manufacturing, transportation and new energy, the market demand for environmentally friendly high-wear-resistant paint has increased rapidly, so it is urgent to further develop water-based epoxy paint to improve its wear resistance. SUMMARY

[0005] In order to obtain a water-based epoxy paint with better wear resistance, the present application provides a water-based wear-resistant epoxy paint and a preparation method thereof.

[0006] In the first aspect, the present application provides a water-based wear-resistant epoxy paint, which adopts the following technical scheme:

[0007] A water-based wear-resistant epoxy paint, comprising the following raw materials by weight:

[0008] 40-60 parts of water-based epoxy resin, 10-20 parts of water-based curing agent, 0.5-2 parts of dispersant, 0.2-1 part of defoaming agent, 0.3-1.2 parts of leveling agent, 25-30 parts of water and 5-15 parts of core-shell filler, wherein the core-shell filler uses nanosilica as the core material, and a polydopamine shell layer is generated in situ in an alkaline buffer solution by dopamine hydrochloride.

[0009] By adopting the technical scheme, the water-based epoxy resin in the application is used as a base resin, and is crosslinked with a water-based curing agent to form a three-dimensional network polymer, and the crosslinked structure makes the coating film have high strength and hardness, and provides a basis for the wear resistance of the coating. On this basis, the core-shell filler is added in the application, and the addition of the nano filler can fill the micro defects in the coating film and increase the density. In particular, the nano silicon dioxide has extremely high hardness, and the nano size effect is dispersed in the coating film to fill the voids and defects in the coating film and improve the density, thereby enhancing the hardness and wear resistance of the coating film.

[0010] The dopamine hydrochloride generates a polydopamine shell layer in situ in the alkaline buffer, and the polydopamine has good adhesion and reactivity. The surface amino groups of the polydopamine can react with the epoxy groups in the epoxy resin to form a crosslinked network structure. In addition, the polydopamine molecule also contains a catechol group, which can form a covalent bond with the active groups in the epoxy resin or the curing agent. Thus, the interfacial bonding force between the polydopamine and the epoxy resin is further enhanced, the nano filler is more uniformly dispersed in the coating, and the agglomeration of the nano particles is reduced. This helps the nano filler to be embedded in the epoxy resin matrix to improve the density and further improve the wear resistance.

[0011] Optionally, the core-shell filler is prepared by the following method:

[0012] 1) Dissolve the tris-hydroxymethyl aminomethane in water, and adjust the pH value to 8.5 with hydrochloric acid to prepare a Tris buffer solution;

[0013] 2) Disperse the nano silicon dioxide in the Tris buffer solution, ultrasonic treat for 10-20 min, then add dopamine hydrochloride, stir, and react for 8-10 h. After centrifugation, wash with water, and dry to obtain the core-shell filler.

[0014] By adopting the technical scheme, the dopamine is oxidized and self-polymerized on the surface of the nano silicon dioxide to form a polydopamine coating layer in an alkaline environment. The amino groups and catechol active groups or molecules of the polydopamine can form chemical bonds between the epoxy resin and the nano silicon dioxide to improve the interfacial bonding. At the same time, the polydopamine shell layer improves the dispersibility of the nano silicon dioxide in the epoxy resin matrix through steric hindrance and charge repulsion, reduces agglomeration, and improves the wear resistance.

[0015] Optionally, in step 1) of the preparation of the core-shell filler, the molar concentration of the tris-hydroxymethyl aminomethane in the Tris buffer solution is 10-15 mmol / L.

[0016] In step 2), the addition amount of the nano silicon dioxide in the Tris buffer solution is 1-3 g / 100 mL, and the mass ratio of the dopamine hydrochloride to the nano silicon dioxide is 1: (3-5).

[0017] By adopting the technical scheme, the core-shell filler prepared by the above-mentioned adding amount control has better wear resistance when used in paint.

[0018] Optionally, in the preparation of the core-shell filler, in step 2), after the nanosilica is dispersed in the Tris buffer solution and ultrasonic treatment, N-β-aminoethyl-γ-aminopropyl trimethoxysilane is first added, and after stirring for 40-60 min, 3-glycidyl ether propyl trimethoxysilane is continuously added, and after stirring for 20-30 min, dopamine hydrochloride is added.

[0019] By adopting the technical scheme, the N-β-aminoethyl-γ-aminopropyl trimethoxysilane and 3-glycidyl ether propyl trimethoxysilane (GPTMS) double silane system are added before the dopamine hydrochloride is added in the present application, the N-β-aminoethyl-γ-aminopropyl trimethoxysilane containing an amino group is first added, the amino group thereof reacts with the surface hydroxyl group of the nanosilica to form a silicon-oxygen skeleton, and the amino group is exposed to guide the directional deposition of dopamine, and then the 3-glycidyl ether propyl trimethoxysilane containing an epoxy group is added, which is embedded in the intermediate layer to provide an epoxy group compatible with the epoxy resin, and a gradient transition interface is formed.

[0020] The methoxyl group of the 3-glycidyl ether propyl trimethoxysilane is hydrolyzed to form a silicon hydroxyl group, which can form a chemical bond with the nanosilica, and the nanosilica is modified to introduce an epoxy group on the surface of the nanosilica, which has a similar structure to the epoxy resin group, has better compatibility with the epoxy resin, and the ortho-benzene diol group in the polydopamine can also form a cross-linked structure with the epoxy group of the GPTMS and form a cross-linking with the epoxy resin matrix, thereby enhancing the density of the coating system and further improving the wear resistance.

[0021] Optionally, the adding amount of the N-β-aminoethyl-γ-aminopropyl trimethoxysilane is 12-15 wt% of the nanosilica, and the adding amount of the 3-glycidyl ether propyl trimethoxysilane is 5-8 wt% of the nanosilica.

[0022] Optionally, in the preparation of the core-shell filler, in step 2), the dopamine hydrochloride is added at the same time as the addition of the glycidyl methacrylate, and the adding amount of the glycidyl methacrylate is 5-10 wt% of the nanosilica.

[0023] By adopting the technical scheme, when the glycidyl methacrylate is added, the dopamine self-polymerizes to form a polydopamine shell layer under alkaline conditions, meanwhile, the glycidyl methacrylate acts as a comonomer, forms a covalent bond with the hydroxyl groups on the surface of the nanosilica through the epoxy groups, and reacts with active groups in the water-based epoxy resin, thereby enhancing the interfacial bonding between the filler and the epoxy resin matrix, and the introduction of the epoxy groups can also increase the crosslinking density of the shell layer and improve the wear resistance.

[0024] Optionally, during the preparation of the core-shell filler, the core-shell filler prepared in step 2) is added after modification treatment, and the modification treatment operation is as follows:

[0025] The mercaptoacetic acid is dissolved in a Tris buffer solution with a molar concentration of 50 mM and a pH of 8.5 to prepare a mercaptoacetic acid solution, and the concentration of the mercaptoacetic acid in the Tris buffer solution is 10-20 mg / mL.

[0026] Then, the prepared core-shell filler is dispersed in the mercaptoacetic acid solution, the mass ratio of the core-shell filler to the mercaptoacetic acid solution is 1: (2-3), and stirring is performed at room temperature for 2-3 h. After the reaction is completed, centrifugal washing is performed to prepare a post-treatment core-shell filler.

[0027] By adopting the technical scheme, although a large number of catechol structures and primary amine groups on the polydopamine can participate in the curing of the epoxy resin, the crosslinking reaction is limited due to the large steric hindrance. Therefore, in the present application, after the nanosilica surface is polymerized to form a polydopamine shell layer, the quinone group on the polydopamine shell layer is reacted with mercaptoacetic acid containing a mercapto group to introduce a carboxyl group. The carboxyl group can form controllable crosslinking with the epoxy resin or the curing agent, further improve the crosslinking density and the chemical bonding between the filler and the resin matrix, and improve the wear resistance.

[0028] Optionally, the curing agent is selected from amine curing agents, the dispersant is selected from polyethylene glycol polyol dispersants, the defoaming agent is selected from silicone defoaming agents, and the leveling agent is selected from modified silicone leveling agents.

[0029] In a second aspect, the present application provides a preparation method of a water-based wear-resistant epoxy coating, which adopts the following technical scheme:

[0030] A preparation method of a water-based wear-resistant epoxy coating, comprising the following steps:

[0031] The water-based epoxy resin, the dispersant, and 1 / 3-2 / 3 of the water are mixed, and are dispersed at a rotation speed of 1000-1200 r / min for 10-15 min to form a base material;

[0032] Then, the core-shell filler is added to the base material, and the defoaming agent, the leveling agent, and the remaining water are added after continuous stirring for 20-30 min, and stirring is performed for 20-30 min.

[0033] After cooling to 20-25℃, add water-based curing agent, stir at 300-500r / min for 15-20min, then stand for 5-15min, to prepare water-based wear-resistant epoxy coating.

[0034] By adopting the technical scheme, the method is simple and convenient, and easy to operate.

[0035] In summary, the present application has the following beneficial effects:

[0036] 1. In the present application, core-shell fillers are added. The addition of nano fillers can fill the micro defects in the coating film, increase the density, thereby enhancing the hardness and wear resistance of the coating film. On this basis, polydopamine shell is generated in situ in the alkaline buffer solution. Polydopamine has good adhesion and reactivity. The surface amino group can react with the epoxy group in the epoxy resin to form a crosslinked network structure. Moreover, the polydopamine molecule also contains a catechol group, which can form a covalent bond with the active groups in the epoxy resin or curing agent. This further enhances the interfacial bonding force between polydopamine and epoxy resin, making the dispersion of nano fillers more uniform in the coating, and also reducing the agglomeration of nano particles. This helps the nano fillers to be embedded in the epoxy resin matrix, improves the density, and further improves the wear resistance.

[0037] 2. In the present application, N-β-aminoethyl-γ-aminopropyl trimethoxysilane and 3-glycidyl ether propyl trimethoxysilane (GPTMS) double silane system are added before the addition of dopamine hydrochloride. First, N-β-aminoethyl-γ-aminopropyl trimethoxysilane containing amino groups is added. The amino group reacts with the surface hydroxyl group of silicon dioxide to form a silicon-oxygen skeleton, and exposes the amino group for guiding the directional deposition of dopamine. Then, 3-glycidyl ether propyl trimethoxysilane containing epoxy groups is added. It is embedded in the intermediate layer and provides epoxy groups compatible with epoxy resin, forming a gradient transition interface. The compatibility with epoxy resin is better, further improving the wear resistance. DETAILED DESCRIPTION

[0038] The present application is further described in detail below in conjunction with the examples. It is particularly noted that: in the following examples, the specific conditions are not specified, and the conventional conditions or the conditions recommended by the manufacturer are used. In the following examples, the raw materials used can be obtained from ordinary market sources unless otherwise specified.

[0039] In the following examples, the water-based curing agent is selected from amine curing agent, and more specifically, AB-HGF-100 water-based epoxy curing agent from Zhejiang Anbang New Material Development Co., Ltd. is selected.

[0040] The water-based epoxy resin is selected from S-48 type product sold by Guangdong Shuntian New Material Co., Ltd.

[0041] The dispersant is selected from polyethylene glycol type polyol dispersant, and specifically selected from PEG-1000;

[0042] The defoaming agent is selected from organic silicon defoaming agent, and specifically selected from BYK1765 defoaming agent of Dongguan Caihua Plastic Technology Co., Ltd., which is used in the epoxy resin system.

[0043] The leveling agent is selected from modified organic silicon leveling agent, and specifically selected from organic silicon leveling agent of HY-307N of Shanghai Huiyan New Material Co., Ltd., and the main component is polyether modified polysiloxane.

[0044] The following preparation example is a preparation example of the core-shell filler

[0045] Preparation Example 1

[0046] A preparation method of a core-shell filler, comprising the following steps:

[0047] 1) After dissolving trimethylol aminomethane in water, adjust the pH value to 8.5 with hydrochloric acid to prepare Tris buffer, and the molar concentration of trimethylol aminomethane in the Tris buffer is 12 mmol / L;

[0048] 2) Disperse nano-silicon dioxide in the Tris buffer, the addition amount of nano-silicon dioxide in the Tris buffer is 2 g / 100 mL (that is, 2 g of nano-silicon dioxide is added to every 100 mL of Tris buffer), ultrasonic treatment for 15 min, then add 4-methoxy dopamine hydrochloride, and the mass ratio of 4-methoxy dopamine hydrochloride to nano-silicon dioxide is 1:4, stir, react for 9 h, centrifuge, wash with water, and dry to obtain the core-shell filler.

[0049] Preparation Example 2

[0050] A preparation method of a core-shell filler, comprising the following steps:

[0051] 1) After dissolving trimethylol aminomethane in water, adjust the pH value to 8.5 with hydrochloric acid to prepare Tris buffer, and the molar concentration of trimethylol aminomethane in the Tris buffer is 10 mmol / L;

[0052] 2) Disperse nano-silicon dioxide in the Tris buffer, the addition amount of nano-silicon dioxide in the Tris buffer is 1 g / 100 mL (that is, 1 g of nano-silicon dioxide is added to every 100 mL of Tris buffer), ultrasonic treatment for 10 min, then add 4-methoxy dopamine hydrochloride, and the mass ratio of 4-methoxy dopamine hydrochloride to nano-silicon dioxide is 1:3, stir, react for 8 h, centrifuge, wash with water, and dry to obtain the core-shell filler.

[0053] Preparation Example 3

[0054] A method for preparing a core-shell filler, comprising the following steps:

[0055] 1) Tris buffer solution was prepared by dissolving trimethylol aminomethane in water and adjusting the pH value to 8.5 with hydrochloric acid, wherein the molar concentration of trimethylol aminomethane in the Tris buffer solution was 15 mmol / L;

[0056] 2) Nano-silica was dispersed in the Tris buffer solution, and the addition amount of nano-silica in the Tris buffer solution was 3 g / 100 mL (i.e. 1-3 g of nano-silica was added to 100 mL of the Tris buffer solution), and then ultrasonic treatment was performed for 20 min, and then 4-methoxy dopamine hydrochloride was added, and the mass ratio of 4-methoxy dopamine hydrochloride to nano-silica was 1:5, and stirring was performed, and reaction was performed for 10 h, and then water washing was performed after centrifugation, and then drying was performed to obtain the core-shell filler.

[0057] Preparation Example 4

[0058] A method for preparing a core-shell filler, which was performed according to the method in Preparation Example 1, except that in step 2), after the nano-silica was dispersed in the Tris buffer solution and ultrasonic treatment was performed, N-β-aminoethyl-γ-aminopropyl trimethoxysilane (KH-792) was first added, stirring was performed for 50 min, then 3-glycidyl ether propyl trimethoxysilane (KH-560) was continuously added, stirring was continuously performed for 25 min, and then 4-methoxy dopamine hydrochloride was added.

[0059] The addition amount of N-β-aminoethyl-γ-aminopropyl trimethoxysilane was 13 wt% of the nano-silica, and the addition amount of 3-glycidyl ether propyl trimethoxysilane was 6 wt% of the nano-silica.

[0060] Preparation Example 5

[0061] A method for preparing a core-shell filler, which was performed according to the method in Preparation Example 1, except that in step 2), after the nano-silica was dispersed in the Tris buffer solution and ultrasonic treatment was performed, N-β-aminoethyl-γ-aminopropyl trimethoxysilane (KH-792) was first added, stirring was performed for 40 min, then 3-glycidyl ether propyl trimethoxysilane (KH-560) was continuously added, stirring was continuously performed for 20 min, and then 4-methoxy dopamine hydrochloride was added.

[0062] The addition amount of N-β-aminoethyl-γ-aminopropyl trimethoxysilane was 12 wt% of the nano-silica, and the addition amount of 3-glycidyl ether propyl trimethoxysilane was 5 wt% of the nano-silica.

[0063] Preparation Example 6

[0064] A preparation method of a core-shell filler, according to the method in Preparation Example 1, the difference is that in step 2), after ultrasonic treatment of dispersing nano-silica in Tris buffer solution, first add N-β-aminoethyl-γ-aminopropyl trimethoxysilane (KH-792), stir for 60 min, then continue to add 3-glycidyl ether propyl trimethoxysilane (KH-560), continue to stir for 30 min, then add 4-methoxy dopamine hydrochloride.

[0065] Among them, the addition amount of N-β-aminoethyl-γ-aminopropyl trimethoxysilane is 15wt% of nano-silica, and the addition amount of 3-glycidyl ether propyl trimethoxysilane is 8wt% of nano-silica.

[0066] Preparation Example 7

[0067] A preparation method of a core-shell filler, according to the method in Preparation Example 4, the difference is that in step 2), KH-792 and KH-560 are replaced by KH-550 in equal amounts.

[0068] Preparation Example 8

[0069] A preparation method of a core-shell filler, according to the method in Preparation Example 4, the difference is that in step 2), 4-methoxy dopamine hydrochloride is added at the same time, and glycidyl methacrylate is also added, and the addition amount of glycidyl methacrylate is 7wt% of nano-silica.

[0070] Preparation Example 9

[0071] A preparation method of a core-shell filler, according to the method in Preparation Example 4, the difference is that in step 2), 4-methoxy dopamine hydrochloride is added at the same time, and glycidyl methacrylate is also added, and the addition amount of glycidyl methacrylate is 5wt% of nano-silica.

[0072] Preparation Example 10

[0073] A preparation method of a core-shell filler, according to the method in Preparation Example 4, the difference is that in step 2), 4-methoxy dopamine hydrochloride is added at the same time, and glycidyl methacrylate is also added, and the addition amount of glycidyl methacrylate is 10wt% of nano-silica.

[0074] Example 1

[0075] A preparation method of a water-based wear-resistant epoxy coating, comprising the following steps:

[0076] Mix 50 kg of waterborne epoxy resin, 1 kg of dispersant and 20 kg of water at a rotational speed of 1100 r / min for 12 min to form a base;

[0077] Then add 10 kg of the core-shell filler prepared in Preparation Example 1 to the base, continue stirring for 25 min, and then add 0.5 kg of defoaming agent, 0.6 kg of leveling agent and 8 kg of water, and stir for 20-30 min;

[0078] After cooling to 20℃, add 15 kg of waterborne curing agent, stir at 400 r / min for 20 min, and then stand for 10 min to prepare a waterborne wear-resistant epoxy coating.

[0079] Example 2

[0080] A method for preparing a waterborne wear-resistant epoxy coating, comprising the following steps:

[0081] Mix 40 kg of waterborne epoxy resin, 0.5 kg of dispersant and 8.5 kg of water at a rotational speed of 1000 r / min for 10 min to form a base;

[0082] Then add 5 kg of the core-shell filler prepared in Preparation Example 2 to the base, continue stirring for 20 min, and then add 0.2 kg of defoaming agent, 0.3 kg of leveling agent and 11.5 kg of water, and stir for 20 min;

[0083] After cooling to 20℃, add 10 kg of waterborne curing agent, stir at 300 r / min for 15 min, and then stand for 5 min to prepare a waterborne wear-resistant epoxy coating.

[0084] Example 3

[0085] A method for preparing a waterborne wear-resistant epoxy coating, comprising the following steps:

[0086] Mix 60 kg of waterborne epoxy resin, 2 kg of dispersant and 20 kg of water at a rotational speed of 1200 r / min for 15 min to form a base;

[0087] Then add 15 kg of the core-shell filler prepared in Preparation Example 3 to the base, continue stirring for 30 min, and then add 1 kg of defoaming agent, 1.2 kg of leveling agent and 10 kg of water, and stir for 30 min;

[0088] After cooling to 25℃, add 20 kg of waterborne curing agent, stir at 500 r / min for 20 min, and then stand for 15 min to prepare a waterborne wear-resistant epoxy coating.

[0089] Examples 4-10

[0090] A preparation method of a waterborne wear-resistant epoxy coating was carried out according to the method in Example 1, except that the core-shell filler was replaced by the core-shell filler prepared in Preparation Example 4-10.

[0091] Example 11

[0092] A preparation method of a waterborne wear-resistant epoxy coating was carried out according to the method in Example 4, except that the core-shell filler was added after modification, and the modification was carried out according to the following steps:

[0093] Tris buffer solution with a molar concentration of 50 mM (the molar concentration of Tris in Tris is 50 mmol / L) and a pH of 8 was prepared by dissolving Tris in water and adjusting the pH to 8.5 with hydrochloric acid;

[0094] Then, a mercaptoacetic acid solution was prepared by dissolving mercaptoacetic acid in Tris buffer solution with a molar concentration of 50 mM and a pH of 8.5, and the concentration of mercaptoacetic acid in the Tris buffer solution was 15 mg / mL;

[0095] Then, the core-shell filler prepared in Preparation Example 4 was dispersed in the mercaptoacetic acid solution, and the mass ratio of the core-shell filler to the mercaptoacetic acid solution was 1:2.5. After stirring at room temperature for 2.5 h, the reaction was completed, and the treated core-shell filler was obtained by centrifugal washing. Then, the treated core-shell filler was added to the base material.

[0096] Example 12

[0097] A preparation method of a waterborne wear-resistant epoxy coating was carried out according to the method in Example 4, except that the core-shell filler was added after modification, and the modification was carried out according to the following steps:

[0098] Tris buffer solution with a molar concentration of 50 mM (the molar concentration of Tris in Tris is 50 mmol / L) and a pH of 8 was prepared by dissolving Tris in water and adjusting the pH to 8.5 with hydrochloric acid;

[0099] Then, a mercaptoacetic acid solution was prepared by dissolving mercaptoacetic acid in Tris buffer solution with a molar concentration of 50 mM and a pH of 8.5, and the concentration of mercaptoacetic acid in the Tris buffer solution was 10 mg / mL;

[0100] Then, the core-shell filler prepared in Preparation Example 4 was dispersed in the mercaptoacetic acid solution, and the mass ratio of the core-shell filler to the mercaptoacetic acid solution was 1:2. After stirring at room temperature for 2 h, the reaction was completed, and the treated core-shell filler was obtained by centrifugal washing. Then, the treated core-shell filler was added to the base material.

[0101] Example 13

[0102] A preparation method of a waterborne wear-resistant epoxy coating was carried out according to the method in Example 4, except that the core-shell filler was added after modification, and the modification was specifically as follows:

[0103] Tris buffer solution with a molar concentration of 50 mM (the molar concentration of Tris in Tris is 50 mmol / L) and a pH of 8 was prepared by dissolving Tris in water and adjusting the pH to 8.5 with hydrochloric acid;

[0104] Then, mercaptoacetic acid solution was prepared by dissolving mercaptoacetic acid in Tris buffer solution with a molar concentration of 50 mM and a pH of 8.5, and the concentration of mercaptoacetic acid in the Tris buffer solution was 20 mg / mL;

[0105] Then, the core-shell filler prepared in Preparation Example 4 was dispersed in the mercaptoacetic acid solution, and the mass ratio of the core-shell filler to the mercaptoacetic acid solution was 1:3. After stirring at room temperature for 3 h, the post-treatment core-shell filler was prepared by centrifugation and washing. Then, the prepared post-treatment core-shell filler was added to the base material.

[0106] Comparative Example 1

[0107] A preparation method of a waterborne wear-resistant epoxy coating was carried out according to the method in Example 1, except that the core-shell filler was replaced by an equal amount of nano-silica.

[0108] Comparative Example 2

[0109] A preparation method of a waterborne wear-resistant epoxy coating was carried out according to the method in Example 1, except that the core-shell filler was replaced by an equal amount of nano-silica, and silane coupling agent KH-550 was added at the same time as the nano-silica, and the amount of KH-550 added was 10 wt% of the nano-silica.

[0110] Performance detection

[0111] The epoxy coatings prepared in the above examples and comparative examples were coated on cold-rolled steel sheets to prepare film test according to the method in GB / T 1768-2006, the dry film thickness was 30 μm, and the Taber wear test was carried out by using CS-10 grinding wheel under a load of 1000 g for 1000 revolutions, and the mass loss was counted. The results are shown in Table 1 below.

[0112] Table 1:

[0113]

[0114] Referring to the test results in Table 1 above, the epoxy coating prepared in the present application has excellent wear resistance, with wear mass < 50 mg. In combination with the test results in Examples 1-3, the use of nano-silica hardness and nano-filling in the core-shell filler increases the density, the cross-linked network is formed between the polydopamine layer and the epoxy group, the nano-filler aggregation is reduced, the dispersion is improved, and the cross-linked density is increased. Ultimately, the core-shell combination reduces aggregation through chemical bonding and steric hindrance effect, enhances the density of the coating film, and significantly improves the wear resistance. In combination with the tests of Example 1 and Examples 4-6, after the dispersion of nano-silica in Tris buffer, first, N-β-aminoethyl-γ-aminopropyl trimethoxysilane is used for the directional guidance of dopamine polymerization, and 3-glycidyl ether propyl trimethoxysilane is embedded in the shell to form a gradient transition interface, which enhances the compatibility with the epoxy resin and further improves the wear resistance. In combination with the test results of Example 7, when only ordinary amino silane coupling agent is added, the wear resistance is obviously insufficient compared with Example 4. The gradient interface in Examples 4-6 is more helpful to the compatibility of the epoxy resin matrix and improves the wear resistance.

[0115] In combination with the test results of Example 1 and Examples 8-10, when dopamine hydrochloride is added at the same time, the wear resistance is further improved when glycidyl methacrylate is added. The introduction of epoxy monomers further improves the compatibility in the epoxy resin matrix. In combination with the test results of Examples 11-13, after the core-shell filler is post-treated, the introduction of carboxyl groups can form additional cross-linking points to further improve the wear resistance. In combination with the test results of Comparative Example 1 and Comparative Example 2, when nano-silica is directly added, its dispersion is poor and the interface combination with the resin matrix leads to poor wear resistance. In Comparative Example 2, nano-silica and silane coupling agent are added at the same time, which improves the wear resistance compared with Comparative Example 1, but is still much weaker than Example 1.

[0116] In addition, the epoxy coating prepared in Examples 1-13 of the present application is subjected to 800h salt spray resistance test according to GB / T 1771-2007, and no rusting, peeling and other phenomena occur after 800h, and the salt spray resistance is excellent.

[0117] The specific embodiments are only an explanation of the present application, which is not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, but as long as the scope of the claims of the present application is within the scope of the patent law.

Claims

1. A water-based wear-resistant epoxy coating, characterized in that, Including the following parts by weight of raw materials: The mixture comprises 40-60 parts waterborne epoxy resin, 10-20 parts waterborne curing agent, 0.5-2 parts dispersant, 0.2-1 part defoamer, 0.3-1.2 parts leveling agent, 25-30 parts water, and 5-15 parts core-shell filler, wherein the core-shell filler is added after post-modification treatment. The post-modification treatment procedure is as follows: A mercaptoacetic acid solution was prepared by dissolving mercaptoacetic acid in a Tris buffer solution with a molar concentration of 50 mM and a pH of 8.

5. The concentration of mercaptoacetic acid in the Tris buffer solution was 10-20 mg / mL. The obtained core-shell packing material was then dispersed in a mercaptoacetic acid solution at a mass ratio of 1:(2-3). The mixture was stirred at room temperature for 2-3 hours. After the reaction was complete, the mixture was centrifuged and washed to obtain the post-treated core-shell packing material. The core-shell packing material was prepared by the following method: 1) Tris buffer solution was prepared by dissolving tris(hydroxymethyl)aminomethane in water and adjusting the pH to 8.5 with hydrochloric acid. 2) Disperse nano-silica in Tris buffer, sonicate for 10-20 min, then add dopamine hydrochloride, stir, react for 8-10 h, centrifuge, wash with water, and dry to obtain core-shell packing material; In step 2), after dispersing nano-silica in Tris buffer and sonicating it, N-β-aminoethyl-γ-aminopropyltrimethoxysilane is first added and stirred for 40-60 min. Then, 3-glycidoxypropyltrimethoxysilane is added and stirred for another 20-30 min before adding dopamine hydrochloride.

2. The water-based wear-resistant epoxy coating according to claim 1, characterized in that: In the preparation of the core-shell packing material, in step 1), the molar concentration of tris(hydroxymethyl)aminomethane in the Tris buffer is 10-15 mmol / L; In step 2), the amount of nano-silica added to Tris buffer is 1-3 g / 100 mL, and the mass ratio of dopamine hydrochloride to nano-silica is 1:(3-5).

3. The water-based wear-resistant epoxy coating according to claim 1, characterized in that: The amount of N-β-aminoethyl-γ-aminopropyltrimethoxysilane added is 12-15 wt% of nano-silica, and the amount of 3-glycidyl etheroxypropyltrimethoxysilane added is 5-8 wt% of nano-silica.

4. The water-based wear-resistant epoxy coating according to claim 1, characterized in that: During the preparation of the core-shell filler, in step 2), while adding dopamine hydrochloride, glycidyl methacrylate is also added, and the amount of glycidyl methacrylate added is 5-10 wt% of nano-silica.

5. The water-based wear-resistant epoxy coating according to claim 1, characterized in that: The water-based curing agent is an amine-based curing agent, the dispersant is a polyethylene glycol-type polyol dispersant, the defoamer is an organosilicon defoamer, and the leveling agent is a modified organosilicon leveling agent.

6. The method for preparing the waterborne wear-resistant epoxy coating as described in any one of claims 1-5, characterized in that: Includes the following steps: Mix waterborne epoxy resin, dispersant and 1 / 3-2 / 3 water, and disperse at a speed of 1000-1200 r / min for 10-15 min to form a base material; Then add the post-treatment core-shell filler to the base material, continue stirring for 20-30 minutes, then add the defoamer, leveling agent and the remaining water, and stir for 20-30 minutes. After cooling to 20-25℃, add water-based curing agent, stir at 300-500r / min for 15-20min, and then let stand for 5-15min to obtain water-based wear-resistant epoxy coating.

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