A kind of corrosion-resistant environmentally friendly coating and preparation method thereof

Abstract

The invention discloses a corrosion-resistant environmentally friendly coating, belongs to the technical field of environmentally friendly coatings, and comprises an A component and a B component. The A component comprises the following raw materials in parts by weight: 45-55 parts of water-based epoxy resin and 35-50 parts of deionized water; the B component comprises the following raw materials in parts by weight: 20-35 parts of a curing agent; the curing agent structure contains a diamino structure, can be used for curing the epoxy resin, and also contains a carbon-carbon double bond, can undergo carbon-carbon double bond addition with graphene grafted with KH570, and is grafted on the surface of the graphene; the introduction of graphene can, through the functional characteristics of a unique two-dimensional layered structure of the graphene, on the one hand, give the epoxy resin excellent corrosion resistance, and on the other hand, improve the combination of the graphene and the epoxy resin; and the fluorine element is introduced into the structure of the modifier, and when participating in the curing of the epoxy resin, can give the coating excellent hydrophobicity, and improve the self-cleaning performance of the coating.

Description

Technical Field

[0001] The present invention relates to the technical field of environmentally friendly coatings, and in particular to a corrosion-resistant environmentally friendly coating and a preparation method thereof. Background Art

[0002] Compared with organic solvent-based paints, water-based paints use water as a dispersion medium and diluent, which reduces the emission of volatile organic solvents (VOC), reduces resource and energy consumption, and is convenient for transportation and storage. With the increase of people's environmental awareness, the relevant environmental regulations on the production and use of chemical products are becoming more and more stringent, so water-based environmentally friendly paints have become the mainstream direction of the development of the modern coatings industry.

[0003] Waterborne epoxy coatings account for about 12% of the global anti-corrosion coatings market. They use water as a dispersion medium, thus avoiding the disadvantages of using organic solvents, such as flammability, harmfulness, and high cost. Compared with solvent-based epoxy coatings, waterborne epoxy coatings have obvious advantages: lower levels of volatile organic compounds, less odor, lower flammability, and easier to clean up with water. The reduction in volatile organic coating emissions reduces its potential harm to the environment and human health, while meeting the emission regulations specified by legislation. In addition, the ability to cure at room temperature and in humid spaces and having a higher cross-linking density are significant advantages of waterborne epoxy anti-corrosion coatings.

[0004] Epoxy resin-based anti-corrosion coatings are the most widely used anti-corrosion coatings. Fillers need to be added to epoxy resin coatings to improve their anti-corrosion properties, and curing agents also need to be added to epoxy resin coatings to solidify them into films. Common fillers are inert and only serve to improve the anti-corrosion properties of the coating, but cannot achieve the curing of the coating. Currently, graphene modification treatment with simple process and low cost is the future development direction, but the commonly used modification methods are complicated to operate, such as: strong acid process and complex processing equipment are required, and there are disadvantages such as high processing cost and time-consuming.

[0005] Graphene nano-flakes can be stacked and distributed in the coating to form a "maze effect", extending the penetration path of the corrosive medium in the coating, thereby improving the coating's anti-corrosion ability. The basic structure of graphene is a two-dimensional crystal composed of carbon atoms with only one atomic thickness. Graphene is the thinnest, strongest, and most conductive and thermally conductive new nanomaterial discovered so far, but there are no active points on the surface of graphene that can react, making it difficult to modify it. Graphene oxide has active points such as hydroxyl, carboxyl, and epoxy groups. Commercially available graphene oxide is divided into single-layer graphene, double-layer graphene, and multi-layer graphene; but the molecular structures of graphene oxide and epoxy resin are very different, and the interface compatibility between them is poor. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a corrosion-resistant and environmentally friendly coating and a preparation method thereof.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A corrosion-resistant and environmentally friendly coating, comprising component A and component B, wherein component A comprises the following raw materials in parts by weight: 45-55 parts of water-based epoxy resin, and 35-50 parts of deionized water;

[0009] The B component includes the following raw materials in parts by weight: 20-35 parts of curing agent;

[0010] The curing agent is prepared by the following steps:

[0011] Step S1, adding 2,2′-diallylbisphenol A to dichloromethane, adding 2-chloro-5-nitrotrifluorotoluene and potassium carbonate, stirring at a uniform speed and heating to 85-100° C., keeping the temperature under reflux for 10 hours to obtain intermediate 1, wherein the amount ratio of 2,2′-diallylbisphenol A, 2-chloro-5-nitrotrifluorotoluene and potassium carbonate is controlled to be 0.1-0.2 mol: 0.2-0.5 mol: 15-16.2 g;

[0012] In step S1, the phenolic hydroxyl group on 2,2′-diallyl bisphenol A first reacts with potassium carbonate to form a potassium phenolate structure, and then undergoes a substitution reaction with 2-chloro-5-nitrotrifluorotoluene containing a chlorinated structure to generate an intermediate 1 containing nitro groups at both ends;

[0013] Step S2, adding a tetrahydrofuran solution of the intermediate 1 and a concentrated hydrochloric acid solution of stannous chloride into a round-bottom flask, reflux for reaction for 8 hours under a nitrogen atmosphere, and after the reaction, dripping a 12% sodium hydroxide solution to adjust the pH until the system pH is 12, extracting and rotary evaporating to obtain a modifier, and controlling the molar ratio of the intermediate 1 to the stannous chloride to be 1:3-5;

[0014] In step S2, stannous chloride is used as a reducing agent to reduce the nitro group on the intermediate 1 to an amino group to obtain a modifier. The modifier structure contains a diamino structure and can be used for curing epoxy resin. The modifier also contains a carbon-carbon double bond and can undergo carbon-carbon double bond addition with graphene grafted with KH570 and grafted on the surface of graphene. The introduction of graphene can give the epoxy resin excellent corrosion resistance through the functional characteristics of the unique two-dimensional layered structure of graphene, and on the other hand, improve the bonding between graphene and epoxy resin. In addition, fluorine element is introduced into the structure of the modifier, and when it participates in the curing of epoxy resin, it can give the coating excellent hydrophobicity and improve the self-cleaning performance of the coating.

[0015] Step S3, adding the prepared modifier and grafted graphene oxide into dichloromethane, adding benzoyl peroxide, raising the temperature to 75-85° C., keeping the temperature for reaction for 2-4 hours, preparing a curing agent, and controlling the weight ratio of the grafted graphene oxide to the modifier to be 1:5-10.

[0016] Furthermore, the tetrahydrofuran solution of the intermediate 1 in step S2 is prepared by mixing the intermediate 1 and tetrahydrofuran in a weight ratio of 1:10-15.

[0017] Furthermore, the concentrated hydrochloric acid solution of stannous chloride in step S2 is prepared by mixing stannous chloride and concentrated hydrochloric acid in a weight ratio of 1:3-5.

[0018] A method for preparing a corrosion-resistant and environmentally friendly coating comprises the following steps:

[0019] The component B is added to the component A and cured to obtain a corrosion-resistant and environmentally friendly coating.

[0020] Beneficial effects of the present invention:

[0021] The invention prepares a corrosion-resistant and environmentally friendly coating, which takes a water-based epoxy resin as a matrix, does not use an organic solvent, meets the requirements of environmental protection, and synthesizes a curing agent. The curing agent is prepared by copolymerizing a modifier with graphene oxide grafted with KH570. The modifier contains a diamino structure in its structure, which can be used for curing the epoxy resin, and also contains a carbon-carbon double bond, which can undergo carbon-carbon double bond addition with graphene grafted with KH570, and is grafted on the surface of the graphene. The introduced graphene can, through the functional characteristics of the unique two-dimensional layered structure of the graphene, on the one hand give the epoxy resin excellent corrosion resistance, and on the other hand improve the bonding between the graphene and the epoxy resin, and the fluorine element is introduced into the structure of the modifier, which can give the coating excellent hydrophobicity when participating in the curing of the epoxy resin, and improve the self-cleaning performance of the coating. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example 1

[0024] A corrosion-resistant and environmentally friendly coating, comprising a component A and a component B, wherein the component A comprises the following raw materials in parts by weight: 45 parts of waterborne epoxy resin and 35 parts of deionized water;

[0025] The B component includes the following raw materials in parts by weight: 20 parts of curing agent;

[0026] The curing agent is prepared by the following steps:

[0027] Step S1, adding 2,2′-diallylbisphenol A to dichloromethane, adding 2-chloro-5-nitrotrifluorotoluene and potassium carbonate, stirring at a uniform speed and heating to 85° C., keeping the temperature under reflux for 10 hours to obtain intermediate 1, wherein the amount ratio of 2,2′-diallylbisphenol A, 2-chloro-5-nitrotrifluorotoluene and potassium carbonate is controlled to be 0.1 mol: 0.2 mol: 15 g;

[0028] Step S2, adding a tetrahydrofuran solution of the intermediate 1 and a concentrated hydrochloric acid solution of stannous chloride into a round-bottom flask, reflux for reaction for 8 hours under a nitrogen atmosphere, and after the reaction, dripping a 12% sodium hydroxide solution to adjust the pH until the system pH is 12, extracting and rotary evaporating to obtain a modifier, and controlling the molar ratio of the intermediate 1 to the stannous chloride to be 1:3;

[0029] Step S3, adding the prepared modifier and grafted graphene oxide into dichloromethane, adding benzoyl peroxide, raising the temperature to 75° C., keeping the temperature for 2 seconds to obtain a curing agent, and controlling the weight ratio of the grafted graphene oxide to the modifier to be 1:5.

[0030] The tetrahydrofuran solution of the intermediate 1 in step S2 is prepared by mixing the intermediate 1 and tetrahydrofuran in a weight ratio of 1:10.

[0031] The concentrated hydrochloric acid solution of stannous chloride in step S2 is prepared by mixing stannous chloride and concentrated hydrochloric acid in a weight ratio of 1:3.

[0032] Example 2

[0033] A corrosion-resistant and environmentally friendly coating, comprising a component A and a component B, wherein the component A comprises the following raw materials in parts by weight: 48 parts of water-based epoxy resin and 40 parts of deionized water;

[0034] The B component includes the following raw materials in parts by weight: 25 parts of curing agent;

[0035] The curing agent is prepared by the following steps:

[0036] Step S1, adding 2,2′-diallylbisphenol A to dichloromethane, adding 2-chloro-5-nitrotrifluorotoluene and potassium carbonate, stirring at a uniform speed and heating to 85-100° C., keeping the temperature under reflux for 10 hours to obtain intermediate 1, wherein the amount ratio of 2,2′-diallylbisphenol A, 2-chloro-5-nitrotrifluorotoluene and potassium carbonate is controlled to be 0.1 mol: 0.3 mol: 15.5 g;

[0037] Step S2, adding a tetrahydrofuran solution of the intermediate 1 and a concentrated hydrochloric acid solution of stannous chloride into a round-bottom flask, reflux for reaction for 8 hours under a nitrogen atmosphere, and after the reaction, dripping a 12% sodium hydroxide solution to adjust the pH until the system pH is 12, extracting and rotary evaporating to obtain a modifier, and controlling the molar ratio of the intermediate 1 to the stannous chloride to be 1:3;

[0038] Step S3, adding the prepared modifier and grafted graphene oxide into dichloromethane, adding benzoyl peroxide, raising the temperature to 80° C., keeping the temperature for 2 seconds to obtain a curing agent, and controlling the weight ratio of the grafted graphene oxide to the modifier to be 1:6.

[0039] The tetrahydrofuran solution of the intermediate 1 in step S2 is prepared by mixing the intermediate 1 and tetrahydrofuran in a weight ratio of 1:12.

[0040] The concentrated hydrochloric acid solution of stannous chloride in step S2 is prepared by mixing stannous chloride and concentrated hydrochloric acid in a weight ratio of 1:4.

[0041] Example 3

[0042] A corrosion-resistant and environmentally friendly coating, comprising component A and component B, wherein component A comprises the following raw materials in parts by weight: 52 parts of waterborne epoxy resin and 45 parts of deionized water;

[0043] The B component includes the following raw materials in parts by weight: 32 parts of curing agent;

[0044] The curing agent is prepared by the following steps:

[0045] Step S1, adding 2,2′-diallylbisphenol A to dichloromethane, adding 2-chloro-5-nitrotrifluorotoluene and potassium carbonate, stirring at a uniform speed and heating to 85-100° C., keeping the temperature under reflux for 10 hours to obtain intermediate 1, wherein the amount ratio of 2,2′-diallylbisphenol A, 2-chloro-5-nitrotrifluorotoluene and potassium carbonate is controlled to be 0.2 mol: 0.4 mol: 16 g;

[0046] Step S2, adding a tetrahydrofuran solution of the intermediate 1 and a concentrated hydrochloric acid solution of stannous chloride into a round-bottom flask, reflux for reaction for 8 hours under a nitrogen atmosphere, and after the reaction, dripping a 12% sodium hydroxide solution to adjust the pH until the system pH is 12, extracting and rotary evaporating to obtain a modifier, and controlling the molar ratio of the intermediate 1 to the stannous chloride to be 1:5;

[0047] Step S3, adding the prepared modifier and grafted graphene oxide into dichloromethane, adding benzoyl peroxide, raising the temperature to 85° C., keeping the temperature for 4 seconds to obtain a curing agent, and controlling the weight ratio of the grafted graphene oxide to the modifier to be 1:10.

[0048] The tetrahydrofuran solution of the intermediate 1 in step S2 is prepared by mixing the intermediate 1 and tetrahydrofuran in a weight ratio of 1:15.

[0049] The concentrated hydrochloric acid solution of stannous chloride in step S2 is prepared by mixing stannous chloride and concentrated hydrochloric acid in a weight ratio of 1:5.

[0050] Example 4

[0051] A corrosion-resistant and environmentally friendly coating, comprising component A and component B, wherein component A comprises the following raw materials in parts by weight: 55 parts of waterborne epoxy resin, 50 parts of deionized water;

[0052] The B component includes the following raw materials in parts by weight: 35 parts of curing agent;

[0053] The curing agent is prepared by the following steps:

[0054] Step S1, adding 2,2′-diallylbisphenol A to dichloromethane, adding 2-chloro-5-nitrotrifluorotoluene and potassium carbonate, stirring at a uniform speed and heating to 100° C., keeping the temperature under reflux for 10 hours, to obtain intermediate 1, wherein the amount ratio of 2,2′-diallylbisphenol A, 2-chloro-5-nitrotrifluorotoluene and potassium carbonate is controlled to be 0.2 mol: 0.5 mol: 16.2 g;

[0055] Step S2, adding a tetrahydrofuran solution of the intermediate 1 and a concentrated hydrochloric acid solution of stannous chloride into a round-bottom flask, reflux for reaction for 8 hours under a nitrogen atmosphere, and after the reaction, dripping a 12% sodium hydroxide solution to adjust the pH until the system pH is 12, extracting and rotary evaporating to obtain a modifier, and controlling the molar ratio of the intermediate 1 to the stannous chloride to be 1:5;

[0056] Step S3, adding the prepared modifier and grafted graphene oxide into dichloromethane, adding benzoyl peroxide, raising the temperature to 85° C., keeping the temperature for reaction for 2-4 hours, preparing a curing agent, and controlling the weight ratio of the grafted graphene oxide to the modifier to be 1:10.

[0057] The tetrahydrofuran solution of the intermediate 1 in step S2 is prepared by mixing the intermediate 1 and tetrahydrofuran in a weight ratio of 1:15.

[0058] The concentrated hydrochloric acid solution of stannous chloride in step S2 is prepared by mixing stannous chloride and concentrated hydrochloric acid in a weight ratio of 1:5.

[0059] Comparative Example 1

[0060] Compared with Example 4, this comparative example uses ethylenediamine as a curing agent.

[0061] Comparative Example 2

[0062] Compared with Example 4, this comparative example uses the modifier synthesized in Example 4 as the curing agent, and the rest is the same as Example 4.

[0063] The curing agent of component B prepared in Example 1-4 and Comparative Example 1-2 was blended with component A, and then coated on a tinplate with a coating thickness of 75 μm. The sample was sealed with paraffin wax to obtain a sample. The water resistance was tested according to the standard of GB / T1733-1993, and the sample was immersed in water for 240 hours. The alkali resistance was tested according to the standard of GB / T9265-2009, and the sample was immersed in a calcium hydroxide solution for 240 hours. The test results are shown in Table 1 below.

[0064] Table 1

[0065]

[0066] It can be seen from Table 1 above that the coatings prepared in the embodiment of the present invention and the comparative example 2 have no gloss loss, discoloration, blistering, wrinkling and falling off after being soaked in water for 240 hours, while the coating prepared in the comparative example 1 has gloss loss and discoloration, no blistering, wrinkling and falling off after being soaked in water for 240 hours, indicating that the curing agent prepared by the present invention gives the coating excellent water resistance; and the coating prepared in the embodiment of the present invention has no gloss loss, discoloration, blistering, wrinkling and falling off after being soaked in calcium hydroxide solution for 240 hours, while the coating prepared in the comparative example has gloss loss and discoloration, no blistering, wrinkling and falling off after being soaked in calcium hydroxide solution for 240 hours, indicating that graphene gives the coating

[0067] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A corrosion-resistant and environmentally friendly coating, characterized in that: The method comprises component A and component B, wherein component A comprises the following raw materials in parts by weight: 45-55 parts of waterborne epoxy resin and 35-50 parts of deionized water; The B component includes the following raw materials in parts by weight: 20-35 parts of curing agent; The curing agent is prepared by the following steps: Step S1, adding 2,2'-diallylbisphenol A to dichloromethane, adding 2-chloro-5-nitrotrifluorotoluene and potassium carbonate, stirring at a uniform speed and heating to 85-100° C., keeping the temperature under reflux for 10 hours, to obtain intermediate 1; Step S2, adding a tetrahydrofuran solution of the intermediate 1 and a concentrated hydrochloric acid solution of stannous chloride into a round-bottom flask, reflux for reaction for 8 hours under a nitrogen atmosphere, and after the reaction, dripping a 12% sodium hydroxide solution to adjust the pH until the system pH is 12, extracting and rotary evaporating to obtain a modifier; Step S3, adding the prepared modifier and grafted graphene oxide into dichloromethane, adding benzoyl peroxide, raising the temperature to 75-85° C., keeping the temperature for reaction for 2-4, to prepare a curing agent; In step S1, the dosage ratio of 2,2'-diallylbisphenol A, 2-chloro-5-nitrotrifluorotoluene and potassium carbonate is controlled to be 0.1-0.2 mol: 0.2-0.5 mol: 15-16.2 g; In step S2, the molar ratio of intermediate 1 to stannous chloride is controlled to be 1:3-5; The tetrahydrofuran solution of intermediate 1 in step S2 is prepared by mixing intermediate 1 and tetrahydrofuran in a weight ratio of 1:10-15; The concentrated hydrochloric acid solution of stannous chloride in step S2 is prepared by mixing stannous chloride and concentrated hydrochloric acid in a weight ratio of 1:3-5; In step S3, the weight ratio of the grafted graphene oxide to the modifier is controlled to be 1:5-10; The grafted graphene oxide is prepared by reacting the hydrolyzed silane coupling agent KH570 with the graphene oxide prepared by Hummer's.

2. The method for preparing a corrosion-resistant and environmentally friendly coating according to claim 1, characterized in that: The steps include: The component B is added to the component A and cured to obtain a corrosion-resistant and environmentally friendly coating.

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