Waterborne epoxy coating as well as preparation method and application thereof

Abstract

The invention relates to a waterborne epoxy coating as well as a preparation method and application thereof. The waterborne epoxy coating comprises the following raw material components in parts by weight: 50-60 parts of waterborne epoxy resin, 0.1-1 part of a wetting leveling agent, 1-5 parts of a coalescing agent, 0.1-2 parts of a thickening agent, 30-40 parts of deionized water, 1-5 parts of matting powder and 20-30 parts of a compound curing agent. Compared with the prior art, the waterborne epoxy coating provided by the invention has the characteristics of good adhesive force on a carbon fiber rail transit locomotive, good water resistance and salt mist resistance and the like; the baking temperature is low (60-80 DEG C), the environment is protected, and the construction is convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a waterborne epoxy coating and a preparation method and application thereof. Background Art

[0002] With the rapid development of the rail transit industry and the introduction of new concepts such as energy conservation and environmental protection, lightweighting has become a hot topic in the field of modern rail transit design and manufacturing.

[0003] The application of carbon fiber composite materials in the field of rail transportation is mainly due to their excellent properties, including high specific strength and specific modulus, which means that they can provide higher strength than traditional metal materials at the same weight while maintaining a lower weight. The use of this material helps to significantly reduce the energy consumption of trains, improve operating efficiency, and reduce the impact on the environment.

[0004] Carbon fiber composite materials are light in weight, high in strength, long in life, and easy to design, process and modify. They are often used in the manufacture of train structural parts and are an important method to achieve lightweight bodywork.

[0005] At this point, there is a need for adaptive coatings on this type of carbon fiber rail transit head. There are already some coatings for carbon fiber rail transit heads on the market, but the feedback is general, and basically there are the following major problems: (1) Appearance problems: Existing coatings may not provide ideal appearance effects, such as color uniformity, gloss and coating flatness, which may affect the overall visual appeal of rail transit. (2) Adhesion problems: The bonding strength between the carbon fiber surface and the coating may be insufficient, causing the coating to easily peel off or bubble, affecting the durability and safety of the structure. (3) Environmental resistance: Especially in railway operations, trains will be exposed to various harsh environments, such as moisture and salt spray. Current coatings show performance degradation after about 300 hours of water and salt spray resistance testing, which may lead to corrosion and structural damage after long-term use.

[0006] In summary, there is still room for improvement in the application of coating technology in carbon fiber composite rail transit locomotives. The research and development of more efficient, durable and environmentally friendly coating solutions is the direction of the industry's continuous attention and efforts. Summary of the invention

[0007] The purpose of the present invention is to provide a water-based epoxy coating and its preparation method and application in order to solve the problems of poor adhesion, poor water and salt spray resistance, and inconvenient construction of the coating on the carbon fiber rail transit head in the prior art. The water-based epoxy coating provided by the present invention has the characteristics of good adhesion, good water and salt spray resistance on the carbon fiber rail transit head; as well as low baking temperature (60-80°C), environmental protection, and convenient construction.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] A water-based epoxy coating comprises the following raw material components in parts by weight:

[0010]

[0011] As a preferred technical solution, the waterborne epoxy coating is composed of the following raw material components in parts by weight:

[0012]

[0013] Furthermore, the solid content of the waterborne epoxy resin is 50-60%.

[0014] As a preferred technical solution, the water-based epoxy resin is Huntsman's ARALDITE PZ 3961-1CI, which is a "Type 1" solid epoxy resin emulsion with good comprehensive properties. The coating made based on this emulsion has a fast drying time, good adhesion, flexibility and corrosion resistance, and has significant performance in water resistance and salt spray resistance compared with other epoxy resins.

[0015] Furthermore, the wetting and leveling agent is an organic silicon surfactant.

[0016] As a preferred technical solution, the wetting and leveling agent is BYK-346 from BYK, which is a polyether-modified polydimethylsiloxane solution used for water-based coatings. It significantly reduces surface tension and has good substrate wetting without foam stabilization. It does not increase surface slip and does not impair recoatability.

[0017] Furthermore, the film-forming aid consists of ethylene glycol butyl ether and dipropylene glycol butyl ether, and the weight ratio of ethylene glycol butyl ether to dipropylene glycol butyl ether is 1:1.

[0018] As a preferred technical solution, the ethylene glycol butyl ether is a medium polar solvent with good solubility and volatility. It can help control the drying speed of the coating and prevent the coating from generating shrinkage holes or sagging during the drying process. At the same time, ethylene glycol butyl ether can also improve the gloss and adhesion of the paint film. Compared with ethylene glycol butyl ether, dipropylene glycol butyl ether has a slower volatilization rate, so it is mainly used as a film-forming aid in the coating, which can improve the leveling of the coating and extend the open time, so that the coating has enough time to form a uniform surface. Its use helps to improve the fullness and water resistance of the paint film. The combined use of the two substances can optimize the film-forming process of the coating. The rapid volatilization of ethylene glycol butyl ether can help the initial film formation, while the slower volatilization of dipropylene glycol butyl ether can ensure the integrity and quality of the film formation. This combination makes the coating have good rheology and workability during the drying process, while improving the performance of the final paint film.

[0019] Furthermore, the thickener is an associative polyurethane thickener.

[0020] As a preferred technical solution, the thickener is Borchi Gel 0620 from OMG, which is a non-ionic polyurethane rheology modifier free of tin, APEO and emulsifier, which can be applied in thick layers on vertical surfaces to effectively prevent sagging and will not cause yellowing or powdering of the cured film.

[0021] Furthermore, the matting powder is silicon dioxide with an organic surface treatment.

[0022] As a preferred technical solution, the matting agent is Tosoh's E-1011, which has a particularly fine particle size and can meet the stringent requirements of thin coating systems. It has a delicate feel and meets customers' increasingly high requirements for the feel of the paint film surface. It has excellent transparency and can be used as a matting agent for matting without losing the base color of the coating film. It has good dispersibility, and the surface is specially treated, so it has high stability in the system and does not produce hard precipitation.

[0023] Furthermore, the compound curing agent is prepared by mixing an amine curing agent with dipropylene glycol butyl ether.

[0024] As a preferred technical solution, the amine curing agent is Huntsman's Aradur 3986, which is specially used for the preparation of water-dilutable epoxy resin systems. This product does not contain volatile amines and solvents, and is specially developed for the preparation of anti-corrosion primers (used in conjunction with water-based epoxy resins) and other water-based coatings. Aradur 3986 epoxy curing agent has the characteristic of visible end of service life (monitored by viscosity increase), and can provide advantages such as fast curing, short surface drying time, and long operating time. It is suitable for modified and unmodified liquid epoxy resins, and is compounded with dipropylene glycol butyl ether. With the above selected The use of PZ 3961-1 epoxy resin can better improve the adhesion and water and salt spray resistance.

[0025] The present invention also provides a method for preparing a waterborne epoxy coating, the specific steps of which are as follows:

[0026] S1. Add a wetting and leveling agent, a film-forming aid, a thickener and deionized water to a water-based epoxy resin in sequence, stir well and add a matting powder as component A;

[0027] S2, mixing the amine curing agent and dipropylene glycol butyl ether to obtain a composite curing agent as component B;

[0028] S3, mixing components A and B to obtain a water-based epoxy coating.

[0029] Furthermore, in step S1, the stirring speed after adding the wetting and leveling agent, the film-forming aid and the thickener is 300-500 rpm, the stirring speed after adding the deionized water is 200-300 rpm, and the stirring speed after adding the matting powder is 500-700 rpm.

[0030] Furthermore, in step S1, the matting powder is added and stirred at high speed until the fineness is less than 20 microns to obtain component A.

[0031] Furthermore, in step S2, the weight ratio of the amine curing agent to dipropylene glycol butyl ether is (80-90): (10-20).

[0032] Furthermore, in step S3, the curing ratio of component A to component B is 100:23.5.

[0033] As a preferred technical solution, the setting of the curing ratio is usually based on the ratio requirements of the chemical reaction. In the present invention, component A is the main agent and component B is the curing agent. The function of the curing agent is to induce polymerization or cross-linking reaction of component A to form a network structure, thereby achieving the purpose of curing or hardening. The curing ratio of 100:23.5 has been strictly optimized experimentally to ensure complete reaction, fast curing speed and optimal material performance after curing. This ratio may involve reaction activity, viscosity control of the material, curing time and physical and chemical properties of the final product. In actual operation, it is usually necessary to accurately measure and mix components A and B to ensure that the expected curing effect is achieved.

[0034] In addition, the present invention also provides an application of a water-based epoxy coating, wherein the water-based epoxy coating is used for coating the surface of a carbon fiber rail transit vehicle head.

[0035] The working principle of the present invention is as follows:

[0036] The main component of waterborne epoxy coating is waterborne epoxy resin, which is made by mixing epoxy resin with waterborne curing agent or emulsifier, and can be dispersed or emulsified in water to reduce pollution to the environment and improve worker safety. The base resin of this coating provides good adhesion, chemical resistance and mechanical properties.

[0037] The function of wetting and leveling agent is to help the solid particles in the coating (such as pigments and fillers) to be better dispersed in the liquid, reduce surface tension, make the coating surface smooth, prevent the appearance of shrinkage cavities and orange peel patterns, and improve the coating effect.

[0038] Film-forming additives play a key role in the drying process of coatings. They can promote the film-forming process of resins, help the coating transform from liquid to solid film, and improve the integrity and physical properties of the coating.

[0039] Thickeners are used to adjust the viscosity of the coating so that it has suitable rheology during construction, is easy to apply, and forms a coating of suitable thickness and hardness after drying.

[0040] Deionized water is a solvent in coatings, used to dilute water-based resins and other ingredients to ensure that the coating can be evenly applied while reducing the impact of minerals in the water on coating performance.

[0041] The function of matting powder is to reduce the gloss of the coating and provide a matte effect. It scatters light and reduces reflection by changing the roughness of the coating surface.

[0042] Compound curing agents are ingredients that react with waterborne epoxy resins. They cross-link with the resin as the paint dries to form a hard, durable paint film, which determines the cure speed and ultimate performance of the coating.

[0043] The present invention provides that the raw material components work synergistically, jointly determining the performance characteristics of the waterborne epoxy coating, such as adhesion, corrosion resistance, drying speed, hardness and glossiness, etc., and is suitable for the protection and decoration of various industrial and architectural surfaces.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] 1. The present invention selects suitable resin wetting and leveling agents, film-forming aids, amine curing agents, etc., and the synergistic proportions lay the foundation for the subsequent preparation of a matching paint film with excellent adhesion and good water and salt spray resistance.

[0046] 2. Compared with the prior art, the present invention has the characteristics of good adhesion on carbon fiber, good water resistance and salt spray resistance, as well as low baking temperature (60-80°C), environmental protection, and convenient construction. DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0048] In the following examples, unless otherwise specified, raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0049] In the following, some embodiments of the present invention are described in detail in conjunction with specific embodiments. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0050] Example 1

[0051] This embodiment provides a water-based epoxy coating, including component A and component B, wherein the curing ratio of component A to component B is 100:23.5;

[0052] The A component is composed of the following raw material components in weight percentage:

[0053] Waterborne epoxy resin ARALDITE PZ 3961-1CI 58.27%,

[0054]

[0055] The B component is composed of the following raw material components in weight percentage:

[0056] Amine curing agent Aradur 3986 83%,

[0057] Dipropylene glycol butyl ether 17%.

[0058] In addition, this embodiment also provides a method for preparing a water-based epoxy coating, and the specific steps are as follows:

[0059] (1) Weigh the waterborne epoxy resin ARALDITE PZ 3961-1CI and put it into a tank;

[0060] (2) Weigh the wetting and leveling agent BYK-346 and put it into the tank while stirring. Stir at medium speed for 10 minutes.

[0061] (3) Weigh ethylene glycol butyl ether and dipropylene glycol butyl ether and put them into the tank in sequence while stirring, and stir at medium speed for 10 minutes;

[0062] (4) Weigh the thickener Borchi Gel 0620 and add it into the tank while stirring, and stir at medium speed for 30 minutes;

[0063] (5) Weigh deionized water and add it into the tank while stirring. Stir at low speed for 10 minutes.

[0064] (6) After weighing, add matting powder E-1011 into the tank while stirring, and stir at high speed for 30 minutes until the fineness reaches less than 20 microns, which is used as component A;

[0065] (7) mixing an amine curing agent and dipropylene glycol butyl ether to obtain a composite curing agent as component B;

[0066] (8) Components A and B are mixed to obtain a water-based epoxy coating.

[0067] In this embodiment, the low-speed stirring is 200-300 rpm, the medium-speed stirring is 300-500 rpm, and the high-speed stirring is 500-700 rpm.

[0068] In addition, this embodiment also provides an application of a water-based epoxy coating, wherein the water-based epoxy coating is applied to the surface of the carbon fiber rail transit vehicle head to form a paint film.

[0069] Performance Testing

[0070] The test results of the paint film properties prepared in this example are shown in Table 1 below.

[0071] Table 1 Test results of paint film properties prepared in Example 1

[0072]

[0073]

[0074] As shown in Table 1, the waterborne epoxy coating in Example 1 has good adhesion on the carbon fiber and good water and salt spray resistance.

[0075] Comparative Example 1:

[0076] This comparative example provides a water-based epoxy coating, comprising component A and component B, wherein the curing ratio of component A to component B is 100:23.5;

[0077] The A component is composed of the following raw material components in weight percentage:

[0078]

[0079] The B component is composed of the following raw material components in weight percentage:

[0080] Amine curing agent Aradur 3986 83%,

[0081] Dipropylene glycol butyl ether 17%.

[0082] In addition, this comparative example also provides a method for preparing a water-based epoxy coating, and the specific steps are as follows:

[0083] (1) Weigh the waterborne epoxy resin ARALDITE PZ 3961-1CI and put it into a tank;

[0084] (2) Weigh the wetting and leveling agent BYK-346 and put it into the tank while stirring. Stir at medium speed for 10 minutes.

[0085] (3) Weigh dipropylene glycol butyl ether and add it into the tank in sequence while stirring, and stir at medium speed for 10 minutes;

[0086] (4) Weigh the thickener Borchi Gel 0620 and add it into the tank while stirring, and stir at medium speed for 30 minutes;

[0087] (5) Weigh deionized water and add it into the tank while stirring. Stir at low speed for 10 minutes.

[0088] (6) After weighing, add matting powder E-1011 into the tank while stirring, and stir at high speed for 30 minutes until the fineness reaches less than 20 microns, which is used as component A;

[0089] (7) mixing an amine curing agent and dipropylene glycol butyl ether to obtain a composite curing agent as component B;

[0090] (8) Components A and B are mixed to obtain a water-based epoxy coating.

[0091] In this comparative example, the low-speed stirring is 200-300 rpm, the medium-speed stirring is 300-500 rpm, and the high-speed stirring is 500-700 rpm.

[0092] In addition, this comparative example also provides an application of a water-based epoxy coating, wherein the water-based epoxy coating is applied to the surface of a carbon fiber rail transit vehicle head to form a paint film.

[0093] Performance Testing

[0094] The test results of the paint film properties prepared in this comparative example are shown in Table 2 below.

[0095] Table 2 Test results of paint film properties prepared in Comparative Example 1

[0096]

[0097] As shown in Table 2, compared with Example 1, the waterborne epoxy coating in Comparative Example 1 becomes rough in appearance and has poorer fineness; the film-forming aid dries slowly and the paint film sags; therefore, the film-forming aid composed of ethylene glycol butyl ether and dipropylene glycol butyl ether has better coating effect and paint film performance, and can improve the comprehensive performance and user-friendliness of the coating.

[0098] Comparative Example 2:

[0099] This comparative example provides a water-based epoxy coating, comprising component A and component B, wherein the curing ratio of component A to component B is 100:15;

[0100] The A component is composed of the following raw material components in weight percentage:

[0101]

[0102]

[0103] The B component is composed of the following raw material components in weight percentage:

[0104] Amine curing agent Aradur 3986 83%,

[0105] Dipropylene glycol butyl ether 17%.

[0106] In addition, this comparative example also provides a method for preparing a water-based epoxy coating, and the specific steps are as follows:

[0107] (1) Weigh the waterborne epoxy resin ARALDITE PZ 3961-1CI and put it into a tank;

[0108] (2) Weigh the wetting and leveling agent BYK-346 and put it into the tank while stirring. Stir at medium speed for 10 minutes.

[0109] (3) Weigh ethylene glycol butyl ether and dipropylene glycol butyl ether and put them into the tank in sequence while stirring, and stir at medium speed for 10 minutes;

[0110] (4) Weigh the thickener Borchi Gel 0620 and add it into the tank while stirring, and stir at medium speed for 30 minutes;

[0111] (5) Weigh deionized water and add it into the tank while stirring. Stir at low speed for 10 minutes.

[0112] (6) After weighing, add matting powder E-1011 into the tank while stirring, and stir at high speed for 30 minutes until the fineness reaches less than 20 microns, which is used as component A;

[0113] (7) mixing an amine curing agent and dipropylene glycol butyl ether to obtain a composite curing agent as component B;

[0114] (8) Components A and B are mixed to obtain a water-based epoxy coating.

[0115] In this comparative example, the low-speed stirring is 200-300 rpm, the medium-speed stirring is 300-500 rpm, and the high-speed stirring is 500-700 rpm.

[0116] In addition, this comparative example also provides an application of a water-based epoxy coating, wherein the water-based epoxy coating is applied to the surface of a carbon fiber rail transit vehicle head to form a paint film.

[0117] Performance Testing

[0118] The test results of the paint film properties prepared in this comparative example are shown in Table 3 below.

[0119] Table 3 Test results of paint film properties prepared in Comparative Example 2

[0120]

[0121]

[0122] As shown in Table 3, compared with Example 1, the adhesion, water resistance and salt spray resistance of the waterborne epoxy coating in Comparative Example 2 are all deteriorated; therefore, when the B component is too little, the curing may not be complete and the material performance is reduced.

[0123] Comparative Example 3:

[0124] This comparative example provides a water-based epoxy coating, comprising component A and component B, wherein the curing ratio of component A to component B is 100:23.5;

[0125] The A component is composed of the following raw material components in weight percentage:

[0126]

[0127] The B component is composed of the following raw material components in weight percentage:

[0128] Amine curing agent Aradur 3986 83%,

[0129] Dipropylene glycol butyl ether 17%.

[0130] In addition, this comparative example also provides a method for preparing a water-based epoxy coating, and the specific steps are as follows:

[0131] (1) Weigh the water-based epoxy resin EP137 and put it into the tank;

[0132] (2) Weigh the wetting and leveling agent BYK-346 and put it into the tank while stirring. Stir at medium speed for 10 minutes.

[0133] (3) Weighing dipropylene glycol butyl ether and ethylene glycol butyl ether, and sequentially adding them into a tank while stirring, and stirring at medium speed for 10 minutes;

[0134] (4) Weigh the thickener Borchi Gel 0620 and add it into the tank while stirring, and stir at medium speed for 30 minutes;

[0135] (5) Weigh deionized water and add it into the tank while stirring. Stir at low speed for 10 minutes.

[0136] (6) After weighing, add matting powder E-1011 into the tank while stirring, and stir at high speed for 30 minutes until the fineness reaches less than 20 microns, which is used as component A;

[0137] (7) mixing an amine curing agent and dipropylene glycol butyl ether to obtain a composite curing agent as component B;

[0138] (8) Components A and B are mixed to obtain a water-based epoxy coating.

[0139] In this comparative example, the low-speed stirring is 200-300 rpm, the medium-speed stirring is 300-500 rpm, and the high-speed stirring is 500-700 rpm.

[0140] In addition, this comparative example also provides an application of a water-based epoxy coating, wherein the water-based epoxy coating is applied to the surface of a carbon fiber rail transit vehicle head to form a paint film.

[0141] Performance Testing

[0142] The test results of the paint film properties prepared in this comparative example are shown in Table 4 below.

[0143] Table 4 Test results of paint film properties prepared in Comparative Example 3

[0144]

[0145] As shown in Table 4, compared with Example 1, the waterborne epoxy resin in Comparative Example 3 was replaced with EP137, and the water and salt spray resistance were significantly reduced; the film-forming aid dried quickly, the paint film had a poor appearance, and there were many particles.

[0146] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A water-based epoxy coating, characterized in that: The raw material components include the following parts by weight:

2. A waterborne epoxy coating according to claim 1, characterized in that: The solid content of the waterborne epoxy resin is 50-60%.

3. A waterborne epoxy coating according to claim 1, characterized in that: The wetting and leveling agent is an organic silicon surfactant.

4. A waterborne epoxy coating according to claim 1, characterized in that: The film-forming aid consists of ethylene glycol butyl ether and dipropylene glycol butyl ether, and the weight ratio of the ethylene glycol butyl ether to the dipropylene glycol butyl ether is 1:

1.

5. A waterborne epoxy coating according to claim 1, characterized in that: The thickener is an associative polyurethane thickener.

6. A waterborne epoxy coating according to claim 1, characterized in that: The matting powder is silicon dioxide with an organic surface treatment.

7. A waterborne epoxy coating according to claim 1, characterized in that: The compound curing agent is prepared by mixing and compounding an amine curing agent and dipropylene glycol butyl ether.

8. A method for preparing a waterborne epoxy coating as claimed in any one of claims 1 to 7, characterized in that: The specific steps are as follows: S1. Add a wetting and leveling agent, a film-forming aid, a thickener and deionized water to a water-based epoxy resin in sequence, stir well and add a matting powder as component A; S2, mixing the amine curing agent and dipropylene glycol butyl ether to obtain a composite curing agent as component B; S3, mixing components A and B to obtain a water-based epoxy coating.

9. The method for preparing a waterborne epoxy coating according to claim 8, characterized in that: In step S1, the stirring speed after adding the wetting and leveling agent, the film-forming aid, and the thickener is 300-500 rpm, the stirring speed after adding deionized water is 200-300 rpm, and the stirring speed after adding the matting powder is 500-700 rpm; In step S1, the matting powder is added and stirred at high speed until the fineness is less than 20 microns to obtain component A; In step S2, the weight ratio of the amine curing agent to dipropylene glycol butyl ether is (80-90): (10-20); In step S3, the curing ratio of component A to component B is 100:23.

5.

10. An application of a waterborne epoxy coating as claimed in any one of claims 1 to 7, characterized in that: The water-based epoxy coating is used for surface coating of carbon fiber rail transit vehicle heads.

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