Epoxy resin-based microcapsule with self-repairing function and preparation method thereof

Abstract

The invention discloses an epoxy resin-based microcapsule with a self-repairing function and a preparation method thereof.The preparation method comprises the steps that epoxy resin is dispersed in an organic solvent, an aqueous solution of polyvinyl alcohol is slowly added, and a first mixture is obtained; the first mixture is mechanically stirred for 30-120 min at the temperature of 20-50 DEG C, and stable oil-in-water emulsion is formed; heating the oil-in-water emulsion to 50 DEG C, and dropwise adding polyether amine to obtain a first solution; mechanical stirring is continued for 30-120 min at the temperature of 30-80 DEG C, and then the capsule wall is completely cured through heat insulation; and repeatedly cleaning and filtering the first solution with deionized water, and then drying to obtain the epoxy resin-based microcapsule. The epoxy resin, the polyether amine and other curing agents are used as the wall materials, high strength and toughness are achieved, the core material can be effectively protected against external influences, the compatibility between the microcapsule shell and the epoxy resin coating matrix is very prominent, and no obvious interface exists.

Description

Technical Field

[0001] The present application belongs to the field of microcapsule technology, and specifically relates to an epoxy resin-based microcapsule with self-repairing function and a preparation method thereof. Background Art

[0002] As an organic coating, epoxy resin cured products have excellent physical barrier properties and excellent adhesion to metals, and are widely used to protect metal substrates. Epoxy resin coatings, which are often used as anti-corrosion paints, will produce microcracks and damage under the action of external forces, temperature and humidity, and chemical erosion, and will gradually lose their protective function. If self-healing epoxy resin coatings are used, their service life can be extended, and microcapsule self-healing technology is currently a hot research topic.

[0003] Microcapsule technology is an important means to achieve self-repairing function. By encapsulating the repair agent inside the microcapsule, when the material is damaged, the microcapsule ruptures and releases the repair agent for repair. However, the preparation method and performance of existing self-repairing microcapsules still have shortcomings, such as poor compatibility with the substrate, insufficient wall material strength, and poor core material release control.

[0004] Patent CN104419298B reports a dual-cured UV roller primer, the main resin component of which is a mixture of epoxy resin and UV resin. The surface of the microencapsulated phenolic amine modified curing agent used is coated with a polymer shell, which plays a role in preventing the phenolic amine modified curing agent from reacting with bisphenol F epoxy resin before the shell is destroyed. When the paint film encounters external force extrusion during the coating process, the microcapsule shell is broken, and the phenolic amine modified curing agent plays a role, causing the bisphenol F epoxy resin to quickly cure into a film.

[0005] Patent CN103881465B provides a method for preparing self-repairing microcapsules for water-based fluorocarbon coatings. The main component of the resin is a mixture of epoxy resin and fluorocarbon resin. Polyurea formaldehyde resin-coated epoxy resin and fluorocarbon resin microcapsules are prepared by an in-situ polymerization two-step method. When microcracks occur in the coating, the microcapsules are destroyed and the capsule core flows out to automatically repair the coating.

[0006] Patent CN111205745B provides a method for preparing a self-repairing anti-corrosion coating, which adopts a method of adding corrosion inhibitor microcapsules, wherein the corrosion inhibitor is the capsule core and the copolymer is the capsule core carrier. The interface performance between the microcapsule wall and the coating resin matrix directly determines whether the microcapsule breaks when the microcracks propagate inside the material, so the selection of the capsule wall is very critical. At the same time, when the material of the capsule wall is different from that of the coating, the mechanical properties of the coating will also be affected.

[0007] However, the current microcapsule self-repairing methods generally have the problem of poor compatibility between microcapsules and polymer matrices, which leads to reduced mechanical properties of the matrix or coating. Therefore, the present invention proposes a method for preparing self-repairing microcapsules to solve this problem. Summary of the invention

[0008] The present application provides an epoxy resin-based microcapsule with self-repairing function and a preparation method thereof, so as to solve the technical problem that the current microcapsule self-repairing method generally has poor compatibility between the microcapsule and the polymer matrix, resulting in reduced mechanical properties of the matrix or coating.

[0009] In order to solve the above technical problems, a technical solution adopted in the present application is: a method for preparing epoxy resin-based microcapsules with self-repairing function, comprising:

[0010] S1. dispersing an epoxy resin in an organic solvent and slowly adding an aqueous solution of polyvinyl alcohol to obtain a first mixture; mechanically stirring the first mixture at 20-50° C. for 30 to 120 min to form a stable oil-in-water emulsion;

[0011] S2. The temperature of the oil-in-water emulsion is heated to 50 ° C and polyetheramine is added dropwise to obtain a first solution; mechanical stirring is continued at 30 to 80 ° C for 30 to 120 min, and then the capsule wall is completely cured by heat insulation;

[0012] S3. The first solution is repeatedly washed and filtered with deionized water, and then dried to obtain epoxy resin-based microcapsules.

[0013] Furthermore, the epoxy resin is a liquid bisphenol A epoxy resin with an average molecular weight between 300 and 500.

[0014] Furthermore, the organic solvent is one or a mixture of aromatic hydrocarbons, alcohol ethers, ketones, and chlorinated hydrocarbons.

[0015] Furthermore, the concentration of the organic solvent is in the range of 20 to 90 wt %.

[0016] Furthermore, the concentration of the aqueous solution of polyvinyl alcohol is 1 to 10 wt %.

[0017] Furthermore, the molar ratio of the epoxy resin to the polyetheramine is 5:1 to 2:1.

[0018] Furthermore, the amine value of the polyetheramine is 200 to 500 mgKOH / g.

[0019] Another technical solution adopted in the present application is: an epoxy resin-based microcapsule with self-repairing function, including a capsule wall and a core material, the core material is a liquid epoxy resin, and the capsule wall is a mixture of polyetheramine and solid epoxy resin.

[0020] Another technical solution adopted in the present application is: a self-repairing coating, comprising epoxy resin and epoxy resin-based microcapsules prepared by the above preparation method.

[0021] Furthermore, the content of the epoxy resin-based microcapsules is 5 to 20 wt % of the epoxy resin.

[0022] The beneficial effects of the present application are as follows: the present application utilizes curing agents such as epoxy resin and polyetheramine as wall materials, which have high strength and toughness, can effectively protect the core material from external influences, and the compatibility between the microcapsule shell and the epoxy resin coating matrix is ​​very outstanding, and there is no obvious interface; at the same time, liquid epoxy resin is used as the core material, which can quickly solidify after the microcapsule is ruptured, fill the damaged area, form a new protective layer, and show good self-healing ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a surface diagram of a plate after the comparative sample in Example 1 of the present application was subjected to a neutral salt spray test for 200 hours;

[0024] Figure 2 This is a surface diagram of a plate after the comparative sample in Example 1 of the present application was subjected to a neutral salt spray test for 360 hours;

[0025] Figure 3 This is a surface diagram of the plate of Sample 1 in Example 1 of the present application after being subjected to a neutral salt spray test for 200 hours;

[0026] Figure 4 This is a surface diagram of the plate of Sample 1 in Example 1 of the present application after being subjected to a neutral salt spray test for 360 hours. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific embodiments.

[0028] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.

[0029] The present application provides a method for preparing epoxy resin-based microcapsules with self-repairing function, comprising:

[0030] S1. dispersing an epoxy resin in an organic solvent and slowly adding an aqueous solution of polyvinyl alcohol to obtain a first mixture; mechanically stirring the first mixture at 20-50° C. for 30 to 120 min to form a stable oil-in-water emulsion;

[0031] S2. The temperature of the oil-in-water emulsion is heated to 50 ° C and polyetheramine is added dropwise to obtain a first solution; mechanical stirring is continued at 30 to 80 ° C for 30 to 120 min, and then the capsule wall is completely cured by heat insulation;

[0032] S3. The first solution is repeatedly washed and filtered with deionized water, and then dried to obtain epoxy resin-based microcapsules.

[0033] The epoxy resin is a liquid bisphenol A epoxy resin with an average molecular weight between 300 and 500. The organic solvent is selected from one or a mixture of aromatic hydrocarbons, alcohol ethers, ketones, and chlorinated hydrocarbons. The concentration range of the organic solvent is 20 to 90 wt%. The concentration of the aqueous solution of polyvinyl alcohol is 1 to 10 wt%. The molar ratio of the epoxy resin to the polyetheramine is 5:1 to 2:1. The polyetheramine is a commercially available product with an amine value of 200 to 500 mgKOH / g and trifunctional or difunctional groups. For example, D230, D400, T403, etc.

[0034] The present application also provides an epoxy resin-based microcapsule with self-repairing function, comprising a capsule wall and a core material, wherein the core material is a liquid epoxy resin, and the capsule wall is a mixture of polyetheramine and solid epoxy resin.

[0035] The present application further provides a self-repairing coating, comprising epoxy resin and epoxy resin-based microcapsules prepared by the above preparation method. The content of the epoxy resin-based microcapsules is 5-20wt% of the epoxy resin.

[0036] Example 1

[0037] 1. Preparation of Microcapsules

[0038] Epoxy resin E51 was dispersed in dichloromethane (concentration of 50wt%), and an aqueous solution of polyvinyl alcohol was slowly added, wherein the concentration of the aqueous solution of polyvinyl alcohol was 4wt%. The mixture was mechanically stirred at 40°C for 60min to form a stable oil-in-water emulsion. The temperature was then heated to 50°C, and polyetheramine D400 (E51:D400 molar ratio of 2.5:1) was added dropwise to the emulsion. Mechanical stirring was continued at 70°C for 60min, and then the capsule wall was completely cured by heat insulation. Finally, the reaction solution was repeatedly washed and filtered with deionized water, and then dried at 40°C to obtain microcapsules.

[0039] 2. Preparation of self-healing coatings

[0040] Sample 1: 15 parts of the prepared microcapsules, 100 parts of water-based epoxy resin emulsion (Huangshan Banghe Synthetic Materials Co., Ltd., BANCO 2060H), 40 parts of curing agent (Huangshan Banghe Synthetic Materials Co., Ltd., BANCO 905), 10 parts of wetting agent (EGOTWIN410), and 10 parts of dispersant (EGO755W) were fully mixed and stirred evenly, and then applied on the surface of Q235 carbon steel. After application, it was dried in an oven at 40°C for 100 hours.

[0041] Comparative sample: No microcapsules were added, and other processes were the same as sample 1.

[0042] According to the ASTM B117 salt spray test standard, a neutral salt spray test was performed on sample 1 and the control sample to further verify the self-healing performance of the coating. Figure 1-4 As shown. Among them, Figure 1 and 2 These are photos of the control samples subjected to the neutral salt spray test for 200h and 360h; Figure 3 and 4 These are photos of sample 1 undergoing a neutral salt spray test for 200 hours and 360 hours.

[0043] Depend on Figure 1-4 It can be seen that after spraying sample 1 and the control sample on the same plate for 200-360 hours, the coating of sample 1 injected with microcapsules effectively prevented corrosion expansion, indicating that the microcapsules can realize the self-repairing ability of the coating.

[0044] The present application provides a novel method for preparing epoxy resin-based microcapsules with self-repairing function, which uses epoxy resin and curing agent as wall materials, liquid epoxy resin as core material, and obtains self-repairing microcapsules with excellent performance through a specific preparation process. The microcapsules have the advantages of high wall material strength, outstanding compatibility with epoxy resin coating bottom layer, stable interface performance, good self-repairing effect, etc.

[0045] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing epoxy resin-based microcapsules with self-repairing function, characterized in that: The following steps are involved: S1. dispersing an epoxy resin in an organic solvent and slowly adding an aqueous solution of polyvinyl alcohol to obtain a first mixture; mechanically stirring the first mixture at 20-50° C. for 30 to 120 min to form a stable oil-in-water emulsion; S2. The temperature of the oil-in-water emulsion is heated to 50°C and polyetheramine is added dropwise to obtain a first solution; mechanical stirring is continued at 30 to 80°C for 30 to 120 min, and then the capsule wall is completely cured by heat insulation; S3. The first solution is repeatedly washed and filtered with deionized water, and then dried to obtain the epoxy resin-based microcapsules.

2. The method according to claim 1, characterized in that The epoxy resin is a liquid bisphenol A epoxy resin with an average molecular weight between 300 and 500.

3. The method according to claim 1, characterized in that The organic solvent is one or a mixture of aromatic hydrocarbons, alcohol ethers, ketones and chlorinated hydrocarbons.

4. The method according to claim 1, characterized in that: The concentration of the organic solvent is in the range of 20 to 90 wt %.

5. The method according to claim 1, characterized in that The concentration of the polyvinyl alcohol aqueous solution is 1-10 wt %.

6. The method according to claim 1, characterized in that The molar ratio of the epoxy resin to the polyetheramine is 5:1 to 2:

1.

7. The method according to claim 1, characterized in that The amine value of the polyetheramine is 200 to 500 mgKOH / g.

8. An epoxy resin-based microcapsule with self-repairing function, characterized in that: The invention comprises a capsule wall and a core material, wherein the core material is liquid epoxy resin, and the capsule wall is a mixture of polyetheramine and solid epoxy resin.

9. A self-repairing coating, characterized in that: The invention comprises epoxy resin and epoxy resin-based microcapsules prepared by the preparation method according to claims 1 to 7. 10 . The self-repairing coating according to claim 9 , wherein the content of the epoxy resin-based microcapsules is 5 to 20 wt % of the epoxy resin.

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