A waterborne one-component epoxy emulsion and a preparation method thereof

Abstract

The application discloses a kind of water-based single-component epoxy emulsion and preparation method thereof.The single-component water-based epoxy emulsion includes epoxy resin modified by ethoxy segment and sulfonate group, and can be emulsified into single-component water-based epoxy.The pH stability of the single-component water-based epoxy is better than that of ion-type epoxy emulsion with neutralized and salified acrylic acid, and the mechanical stability of the emulsion is better due to the introduction of ethoxy segment.The introduction of styrene monomer and / or acrylate monomer can improve the brittle characteristics of the epoxy resin, and the high hardness of the epoxy resin can be considered, so that single-component water-based epoxy coating with good impact resistance and high hardness can be obtained.By introducing imidazole group and a certain amount of dicyandiamide, good coordination with metal zinc ions of antirust pigment in anticorrosive paint can be achieved, and the single-component water-based epoxy coating with anticorrosive performance and self-repairing performance can be obtained.

Description

Technical Field

[0001] This invention belongs to the field of coatings and adhesives, and relates to a water-based dispersible single-component epoxy emulsion and its preparation method. This invention also relates to the application of this water-based epoxy emulsion in the field of rust prevention. Background Technology

[0002] Epoxy resin coatings are widely used in metal corrosion protection due to their excellent anti-corrosion properties. However, oil-based epoxy resin coatings require a large amount of solvent during application. In recent years, due to increased emphasis on health and environmental protection, epoxy coatings have gradually shifted towards high-solids and water-based coatings. Water-based epoxy coatings offer numerous advantages, such as low VOC content, less odor, safer use, water-washable properties, and increasingly mature processing technology, meeting environmental protection and energy-saving requirements, thus rapidly becoming an important development direction for modern coatings. Currently, water-based epoxy coatings are mainly two-component and are used in high-performance container primers, primers and intermediate coats for engineering machinery and rail transportation, architectural coatings, equipment primers, industrial plant floor coatings, transportation vehicle primers, automotive repair primers, and industrial repair primers. However, the application process for two-component coatings is relatively complex. To obtain the required coating performance, suitable epoxy resins and curing agents need to be used in combination. Therefore, in the field of light and medium-light corrosion protection, there is a trend towards using single-component water-based epoxy coatings.

[0003] One-component waterborne epoxy resins can incorporate latent curing agents, meaning they remain stable during storage and are released and cured under specific light / heat conditions during use. However, one-component waterborne epoxy resins with latent curing agents exhibit poor stability, making them unsuitable for practical applications.

[0004] CN103087607B describes a chemical grafting process on macromolecular epoxy resin, followed by the introduction of acrylic acid and neutralization to form a salt, resulting in an ionic, single-component, waterborne epoxy emulsion. However, this system exhibits poor adaptability to pH changes and exhibits poor metal corrosion resistance. Without the addition of curing agents such as amino resins and blocked isocyanates, it cannot meet the salt spray resistance requirements in the field of medium and light-duty corrosion protection.

[0005] Meanwhile, during use, the microstructure of coatings changes due to external environmental influences, generating microcracks that affect coating performance. To improve coating performance, researchers employ self-healing technology to reduce microcrack formation. Based on whether external repair agents are needed during the self-healing process of polymer materials, self-healing materials are divided into two main categories: exogenous self-healing materials and intrinsic self-healing materials. Exogenous self-healing materials include microcapsule-type or microvascular-type materials. Intrinsic self-healing materials, based on dynamically reversible covalent and non-covalent bonds, can be further divided into self-healing materials based on Diels-Alder reactions, disulfide bond reactions, hydrogen bonding, π-π stacking interactions, metal coordination interactions, host-guest interactions, etc.

[0006] CN109280143A utilizes the double bond modification of olefin polymer elastomers by grafting ligand groups such as pyridine and imidazole onto them, enabling cross-linking with metal ions through metal coordination bonds to prepare a self-healing elastomer. CN111925495A synthesizes a polyurethane or polyurea containing ligand groups such as pyridine and imidazole; after adding a certain amount of metal salt, a heat-resistant coating with self-healing properties can be obtained through metal coordination bonds. CN112979921A synthesizes a corrosion-inhibiting epoxy resin containing bisphenol fluorene; its bipyridine structure can rapidly coordinate with ferrous ions, exhibiting certain in-situ repair and corrosion shielding properties.

[0007] In anti-corrosion coatings, rust-inhibiting fillers containing metal ions are commonly found. Based on this, single-component waterborne epoxy can utilize metal coordination to achieve self-healing technology, synthesizing a single-component waterborne epoxy coating with self-healing properties and excellent anti-corrosion performance. Currently, most self-healing materials utilizing metal coordination require the addition of metal ions that are not originally needed, which may affect the overall performance of the material in practical use. Summary of the Invention

[0008] The purpose of this invention is to provide a water-based one-component epoxy emulsion. This water-based one-component epoxy emulsion contains modified epoxy resins with ethoxy groups and sulfonate groups. After grafting modification to introduce styrene monomers and / or acrylate monomers, imidazole containing amine groups and dicyandiamide are added. Following the reaction, water is added to disperse the mixture into a one-component epoxy resin aqueous dispersion. This one-component water-based epoxy emulsion exhibits good stability and, in water-based anti-corrosion coatings, can coordinate with metal ions derived from rust-inhibiting pigments and fillers, demonstrating self-healing properties. However, due to the influence of the system and structure, a single imidazole structure cannot provide sufficient self-healing properties for the coating system. Dicyandiamide needs to be added to promote the coordination between metal ions and imidazole, thereby improving the resin system's self-healing properties and enhancing the anti-corrosion performance of the one-component water-based epoxy emulsion. This results in excellent salt spray resistance for the one-component water-based epoxy emulsion.

[0009] To achieve one aspect of the above-mentioned objectives, the present invention provides the following technical solution:

[0010] An aqueous one-component epoxy emulsion comprising the following components: water, anionic and nonionic modified epoxy resin, styrene monomer and / or acrylate monomer, free radical polymerization initiator, amine-containing imidazole and dicyandiamide, and optionally a solvent.

[0011] As a preferred embodiment, the aqueous single-component epoxy emulsion of the present invention comprises the following components: by mass parts:

[0012]

[0013] As another preferred embodiment, the aqueous one-component epoxy emulsion of the present invention comprises the following components: by mass parts:

[0014]

[0015] The anionic and nonionic modified epoxy resin molecules of the present invention contain ethoxy segments and at least one sulfonate group.

[0016] In one embodiment, the anionic and nonionic modified epoxy resin is obtained by reacting an amine containing a primary amine group with epoxy resin A, wherein the molar ratio of the primary amine group to the epoxy group is 1:6-2:5, preferably 1:5-1:3, and the reaction temperature is 100-120°C.

[0017] The epoxy resin A of this invention comprises the following components:

[0018] Epoxy resin B containing at least two epoxy groups and having an epoxy value of 0.03-0.55;

[0019] Epoxy resin C containing at least one epoxy group and an EO segment;

[0020] Epoxy resin D, obtained by reacting epoxy resin B with aminosulfonate, contains at least one epoxy group.

[0021] The epoxy resin B described in this invention can be saturated or unsaturated, and can be aliphatic, cycloaliphatic, aromatic, or heterocyclic epoxy resin, and may also contain hydroxyl groups. They may also contain other substituents that do not cause interfering side reactions under mixing and reaction conditions, such as alkyl or aryl substituents, ether groups, etc. Preferably, the epoxy resin B can be a polyglycidyl ether or a polyglycidyl ester.

[0022] As a preferred embodiment, the epoxy resin B of the present invention can be a glycidyl ether of a polyphenol or a polyol, wherein the polyphenol is, for example, a mixture of isomers of resorcinol, hydroquinone, 2,2-bis(4′-hydroxyphenyl)propane (bisphenol A), dihydroxydiphenylmethane (bisphenol F), 4,4'-dihydroxydiphenylcyclohexane, 4,4'-dihydroxy-3,3'-dimethyldiphenylpropane, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxybenzophenone, bis(4'-hydroxyphenyl)-1,1-ethane, bis(4'-hydroxyphenyl)-1,1-isobutane, bis(4'-hydroxy-tert-butylphenyl)-2,2-propane, bis(2-hydroxynaphthyl)-methane, 1,5-dihydroxynaphthalene, tris(4-hydroxyphenyl)-methane, bis(4-hydroxyphenyl)ethyl ether, bis(4-hydroxyphenyl) sulfone, and chlorination and bromination products of the aforementioned compounds. The epoxy resin B can also be a polyhydroxy alcohol polyglycidyl ether, such as ethylene glycol-1,2-diglycidyl ether, propylene glycol-1,2-diglycidyl ether, propylene glycol-1,3-diglycidyl ether, butylene glycol diglycidyl ether, pentylene glycol diglycidyl ether, neopentylene glycol diglycidyl ether, hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, high-carbon polyoxyalkylene glycol diglycidyl ether (e.g., high-carbon polyoxyethylene glycol diglycidyl ether and polyoxypropylene glycol diglycidyl ether). Oil ethers, mixed polyoxyethylene-propylene glycol diglycidyl ethers), polyoxybutene glycol diglycidyl ethers, polyglycidyl ethers of glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, and sorbitol, polyglycidyl ethers of alkoxylated polyols such as glycerol, trimethylolpropane, and pentaerythritol, diglycidyl ethers of cyclohexanediol, bis(4-hydroxycyclohexyl)methane, and 2,2-bis(4-hydroxycyclohexyl)propane, and polyglycidyl ethers of castor oil or triglycidyl tri(2-hydroxyethyl) isocyanurate. In addition, the epoxy resin B can also be a polyglycidyl ester of a polycarboxylic acid, which is prepared by reacting epichlorohydrin or similar epoxy compounds with aliphatic, cycloaliphatic or aromatic polycarboxylic acids, such as oxalic acid, succinic acid, adipic acid, glutaric acid, phthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, 2,6-naphthalenedicarboxylic acid and high carbon dicarboxylic acid diglycidyl esters, as dimer or trimer of linolenic acid.

[0023] The epoxy resin C of the present invention can be prepared by one of the following methods: In one embodiment, a polyetheramine is mixed with epoxy resin B, and the epoxy resin C is obtained by a ring-opening reaction between the amino group of the polyetheramine and the epoxy group of the epoxy resin B. The reaction conditions for the ring-opening reaction can be: reacting at 40-140°C, preferably 80-120°C for 1-5 hours, preferably 1-3 hours.

[0024] In another embodiment, a polyether containing at least five ethoxy segments is esterified with an acid anhydride to obtain intermediate product C-1, which is then reacted with epoxy resin B in a ring-opening reaction to obtain epoxy resin C.

[0025] The structural formula of the polyetheramine used in the preparation of epoxy resin C according to the present invention is shown below:

[0026]

[0027] Wherein, R represents an alkyl group with 1-12 carbon atoms, such as hydrogen atom, methyl, or ethyl. R2 represents a hydrogen atom or methyl, and the number average molecular weight of the polyetheramine is 300-3000, preferably 500-2000.

[0028] The structural formula of the polyether used to prepare epoxy resin C according to the present invention is shown below:

[0029]

[0030] Wherein, R represents an alkyl group with 1-12 carbon atoms, such as hydrogen atom, methyl, or ethyl. R1 represents a hydrogen atom or methyl, and the number average molecular weight of the polyether is 300-10000, preferably 500-6000.

[0031] The anhydride used in the preparation of epoxy resin C according to the present invention is an anhydride of a polycarboxylic acid having 2-4 carboxyl groups in its molecule. Preferably, it is an anhydride obtained by intramolecular dehydration of a polycarboxylic acid having 2-3 carboxyl groups. Examples include conventionally known anhydrides such as those derived from aromatic polycarboxylic acids or cyclic aliphatic polycarboxylic acids, but anhydrides derived from aromatic polycarboxylic acids are preferred. Examples of aromatic polycarboxylic acid anhydrides include hexahydrophthalic anhydride, trimellitic anhydride, pyromellitic tetracarboxylic anhydride, and benzophenone-3,3',4,4'-tetracarboxylic anhydride, with hexahydrophthalic anhydride and trimellitic anhydride being preferred. Examples of cyclic aliphatic polycarboxylic acid anhydrides include hydrogenated trimellitic anhydride and hydrogenated pyromellitic tetracarboxylic anhydride.

[0032] In the method for preparing epoxy resin C according to the present invention, the molar ratio of the total amount of anhydride groups (-COOCO-) of the anhydride to the total amount of hydroxyl groups of the polyether is 1-1.2, preferably 1-1.1. The reaction temperature of the esterification reaction can be 40-140℃, preferably 80-140℃; the reaction time can be 1-5 hours, preferably 3-5 hours.

[0033] In one embodiment of the method for preparing epoxy resin C according to the present invention, intermediate product C-1 undergoes a ring-opening reaction with the epoxy groups of epoxy resin B to obtain C. The ring-opening reaction is carried out at 40-140°C for 1-5 hours under the action of a catalyst. The molar ratio of the total amount of epoxy groups provided by epoxy resin B to the total amount of carboxyl groups contained in intermediate product C-1 is at least 1:1, preferably at 80-140°C for 3-5 hours under the action of a catalyst, and the molar ratio of the total amount of epoxy groups provided by epoxy resin B to the total amount of carboxyl groups contained in intermediate product C-1 is 2:1-4:1. The catalyst for the ring-opening reaction is well known in the art, and is, for example, one or more of triethylamine, tetrabutylammonium bromide, triphenylphosphine, triphenylphosphine, and boron trifluoride diethyl ether. Its amount can be more than 0.04 wt% of the total solids in the reaction system, preferably 0.1 wt%-2 wt%.

[0034] In one embodiment, epoxy resin B reacts with aminosulfonate to obtain epoxy resin D containing at least one epoxy group. Those skilled in the art will understand that by controlling the molar ratio of the total amount of epoxy groups provided by epoxy resin B to the total amount of active hydrogen contained in the amino group of the aminosulfonate, epoxy resin D can contain at least one epoxy group. For example, the molar ratio can be greater than 1:1, such as 1.2:1 or 1.5:1 or higher (i.e., when the reaction is complete, some epoxy groups are still present in the reaction system due to excess). Preferably, the molar ratio of the total amount of epoxy groups provided by epoxy resin B to the total amount of active hydrogen contained in the amino group of the aminosulfonate is 2:1-4:1.

[0035] In one embodiment, the aminosulfonate is prepared by neutralizing aminosulfonic acid with a base. To substantially eliminate free base, the degree of neutralization is typically no more than 99%, preferably 90%–98%, such as 95%. The reaction of epoxy resin B with the aminosulfonate requires mixing water with the aminosulfonate. The mass ratio of aminosulfonate to water is not less than 1:20, preferably not less than 1:10, and more preferably not less than 1:5, for example, by introducing water in the form of an aqueous solution containing 20–50 wt% aminosulfonate. After mixing the aminosulfonate with water, it is reacted with epoxy resin B at a temperature of 50–150°C, such as 70, 80, 90, 110, 120, 130, or 140°C, optionally in the presence of a solvent used to reduce the viscosity of the reaction system, to obtain epoxy resin D. Preferably, the reaction temperature is 80–130°C, more preferably 90–100°C. In this invention, "optional" means that it may or may not be present. Solvents that can be used to reduce the viscosity of the reaction system are commonly used and well known in the art. For example, the solvent may be propylene glycol methyl ether, ethylene glycol butyl ether, dipropylene glycol dimethyl ether, acetone, butanone, or butanol.

[0036] The method for preparing the waterborne single-component epoxy emulsion of the present invention includes the following steps: according to the proportion, anionic and nonionic modified epoxy resin and solvent are added to a reactor, heated to 100-120°C, and when the system becomes a homogeneous liquid, a mixture of styrene monomer and / or acrylate monomer and free radical polymerization initiator is added dropwise over 3-8 hours. Then the temperature is lowered to 60-90°C, and imidazole containing amine groups and dicyandiamide are added. The reaction is carried out for 1-3 hours, and water is added at 30-80°C for high-speed dispersion to form a waterborne single-component epoxy emulsion.

[0037] As a preferred approach, anionic and nonionic modified epoxy resin and solvent are added to a reactor and heated to 105-120°C until the system becomes a homogeneous liquid. A mixture of styrene monomer and / or acrylate monomer and free radical polymerization initiator is then added dropwise over 4-6 hours. The temperature is then lowered to 70-90°C, and imidazole and dicyandiamide containing amine groups are added. The reaction is carried out for 1-2 hours, and water is added at 30-60°C for high-speed dispersion to form an aqueous single-component epoxy emulsion.

[0038] The styrene monomer and / or acrylate monomer are one or more of styrene, methyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and isobornyl methacrylate.

[0039] The free radical polymerization initiator is one or more of BPO, TBPO, and AIBN.

[0040] The solvent is one or more of propylene glycol methyl ether, ethylene glycol butyl ether, n-butanol, isopropanol, dipropylene glycol dimethyl ether, acetone, and butanone.

[0041] The amino-containing imidazole is one or more of 2-(4-methyl-1H-imidazol-5-yl)ethylamine, 1-(4-aminobenzyl)-1H-imidazol, 1-methyl-5-aminomethylimidazol, 1-(3-aminopropyl)imidazol, and 2-imidazol-1-ethylamine.

[0042] Those skilled in the art will understand that other additives are usually added to the emulsion, such as thickeners (e.g., U905, U300, etc., added at 0-5 wt% of the total emulsion mass; defoamers such as foamstar2410, 902w, BYK-024, -033, -028, A1001, etc., added at 0-1 wt% of the dispersion), and other commonly used additives. The addition of these additives is well known in the art and will not be described in detail here.

[0043] The beneficial effects of this invention are as follows:

[0044] (1) The single-component aqueous epoxy emulsion of the present invention contains epoxy resin modified with ethoxy segments and sulfonate groups, which can be emulsified into a single-component aqueous epoxy. Compared with ionic epoxy emulsions that introduce acrylic acid to neutralize and form salts, it has better pH stability. At the same time, the introduction of ethoxy segments makes the emulsion more mechanically stable.

[0045] (2) By introducing styrene monomers and / or acrylate monomers to modify epoxy resin, the rigid and brittle properties can be improved, while also taking into account the high hardness of epoxy, thus obtaining a single-component waterborne epoxy coating with good impact resistance and high hardness.

[0046] (3) By introducing olefin monomers to modify epoxy resin, the weather resistance of epoxy can be improved, and a single-component waterborne epoxy coating with good weather resistance and corrosion resistance can be obtained. The single-component waterborne epoxy emulsion of the present invention has the characteristics of good stability, high hardness, and excellent corrosion resistance and weather resistance, and can be applied in the fields of coatings and adhesives.

[0047] (4) By introducing imidazole groups and combining them with a certain amount of dicyandiamide, a good coordination reaction can occur with the zinc ions in the anti-rust pigments and fillers of the anti-corrosion paint, resulting in self-healing properties. This allows for the creation of a single-component waterborne epoxy coating that combines anti-corrosion and self-healing properties. It should be noted that in this resin system, neither imidazole groups nor dicyandiamide alone can achieve a good coordination reaction with zinc ions, thus failing to achieve good self-healing properties. Without any theoretical limitations, the cyano group, carbon-nitrogen double bond, and the tertiary amine structure after the reaction on dicyandiamide form a highly electronegative electron-rich cloud structure, which can promote the coordination reaction between the imidazole ring and zinc ions, enabling this single-component waterborne epoxy system to obtain better self-healing properties. Detailed Implementation

[0048] The present invention will be further described in detail below through embodiments, but it should not be construed as limiting the scope of the invention to the following examples. Various substitutions or modifications made based on ordinary technical knowledge and conventional methods in the art without departing from the above-described methodological spirit of the invention should be included within the scope of the invention.

[0049] The sources of materials used in the following examples / comparative examples are shown in Table 1 below:

[0050] Table 1 Raw Materials and Sources

[0051] Substance Name form supplier CAS number N-Aminoethylethanesulfonic acid solid alading 34730-59-1 Sodium hydroxide solid TCI 1310-73-2 Polyethylene glycol 1000 liquid Han Nong 25322-68-3 Polyethylene glycol 6000 solid Dow 25322-68-3 Polyethylene glycol methyl ether 500 liquid Clariant 9004-74-4 Polyethylene glycol monomethyl ether 4500 solid Clariant 9004-74-4 Epoxy resin (E6 / E20 / E51) solid Baling Petrochemical 25068-38-6 Trimeric triglyceride solid TCI 552-30-7 Hexahydrophthalic anhydride solid TCI 85-42-7 Ethylene glycol butyl ether liquid Dow 111-76-2 octylamine liquid McLean 111-86-4 Triphenylphosphine solid Jianping, Xuzhou 603-35-0 styrene liquid Wanhua 100-42-5 Butyl acrylate liquid Wanhua 141-32-2 Benzoyl peroxide (BPO) solid Aladdin 94-36-0 1-(3-aminopropyl)imidazolium liquid McLean 5036-48-6 2-Imidazol-1-ethylamine liquid Aladdin 5739-10-6 Dicyandiamide solid Aladdin 461-58-5 acrylic acid liquid Wanhua Chemical 79-10-7 Dimethylethanolamine liquid Dow 108-01-0

[0052] The following test methods are used in various embodiments of the present invention:

[0053] (1) Stability testing of dispersion systems and prediction of their shelf life: GT / T 5208;

[0054] (2) Resistance to neutral salt spray: GB / T 1771;

[0055] (3) Impact resistance: GB / T 1732;

[0056] (4) Self-healing rate test: After the coating is formed, a sharp object is used to make a cross mark on the surface of the coating. The coating is then placed in an oven for 2 hours to allow it to self-heal. The changes in the coating before and after repair are observed through an optical microscope.

[0057] (5) Particle size test of dispersion: Dilute the dispersion system with water to a concentration of 170 ppm (mass content), and then test it with a Zetasizer Nano ZS particle size analyzer.

[0058] Unless otherwise specified, the contents mentioned in the following examples / comparative examples are mass contents.

[0059] Preparation of epoxy resin C:

[0060] Example c1: 1000g of melt-dehydrated polyethylene glycol 1000 was injected into a bottle, and the temperature inside the bottle was maintained at 80°C. Then, 338.8g of hexahydrophthalic anhydride was added to the reaction bottle, and the temperature was maintained at 80°C. The reaction was carried out for about 5 hours. After the acid value reached the theoretical value (determined by NaOH back titration, the same below), 836g of epoxy resin E51 was added. After stirring evenly, 2.2g of triphenylphosphine (TPP) catalyst was added, and the reaction was carried out at a constant temperature of 140°C for 3 hours. After the acid value reached the theoretical value, the product was discharged.

[0061] Example c2: 1000g of melt-dehydrated polyethylene glycol 6000 was injected into a bottle, and the temperature inside the bottle was maintained at 100°C. Then, 51.3g of hexahydrophthalic anhydride was added to the reaction bottle, the temperature was raised to 120°C, and the reaction was carried out for about 4 hours. After the acid value reached the theoretical value, 253.4g of epoxy resin E51 was added, and after stirring evenly, 13.0g of triphenylphosphine (TPP) catalyst was added. The reaction was carried out at a constant temperature of 100°C for 4 hours. After the acid value reached the theoretical value, the product was discharged.

[0062] Example c3: 1000g of melt-dehydrated polyethylene glycol monomethyl ether 500 was injected into a bottle, and the temperature inside the bottle was maintained at 80°C. Then, 384g of trimellitic anhydride was added to the reaction bottle, and the temperature was maintained at 80°C for about 5 hours. After the acid value reached the theoretical value, 1520g of epoxy resin E51 was added, and after stirring evenly, 58.1g of triphenylphosphine (TPP) catalyst was added. The reaction was carried out at a constant temperature of 80°C for 5 hours. After the acid value reached the theoretical value, the product was discharged.

[0063] Example c4: 1000g of melt-dehydrated polyethylene glycol monomethyl ether 4500 was injected into a bottle, and the temperature inside the bottle was maintained at 100°C. Then, 46.9g of trimellitic anhydride was added to the reaction bottle, the temperature was raised to 140°C, and the reaction was carried out for about 3 hours. After the acid value reached the theoretical value, 371.6g of epoxy resin E51 was added, and after stirring evenly, 14.2g of triphenylphosphine (TPP) catalyst was added. The reaction was carried out at a constant temperature of 100°C for 4 hours. After the acid value reached the theoretical value, the product was discharged.

[0064] Preparation of epoxy resin D:

[0065] Example d1: 1000g of epoxy resin E20 was dissolved in 300g of ethylene glycol butyl ether. At 90°C, 574.7g of sodium N-aminoethyl ethanesulfonate aqueous solution (N-aminoethyl ethanesulfonate reacts with sodium hydroxide aqueous solution to form a 20% aqueous solution with 90% neutralization) was added dropwise. After adding the solution for 30 minutes, the temperature was maintained and the reaction was carried out for 3 hours before the product was discharged.

[0066] Example d2: 1000g of epoxy resin E06 was dissolved in 300g of ethylene glycol butyl ether. At 95°C, 105.0g of sodium N-aminoethyl ethanesulfonate aqueous solution (N-aminoethyl ethanesulfonate reacts with sodium hydroxide aqueous solution to form a 50% aqueous solution with 98% neutralization) was added dropwise. After adding the solution for 30 minutes, the temperature was maintained and the reaction was carried out for 3 hours before the product was discharged.

[0067] Example d3: 1000g of epoxy resin E20 was dissolved in 300g of ethylene glycol butyl ether. At 100°C, 215.5g of sodium N-aminoethyl ethanesulfonate aqueous solution (N-aminoethyl ethanesulfonate reacts with sodium hydroxide aqueous solution to form a 40% aqueous solution with 95% neutralization) was added dropwise. After adding the solution for 30 minutes, the temperature was maintained and the reaction was carried out for 3 hours before the product was discharged.

[0068] Preparation of epoxy resins simultaneously modified by anions and nonions:

[0069] Example a1: 1000g of epoxy E20, 200g of epoxy obtained in Example c1, and 10g of epoxy obtained in Example d3 were mixed and dissolved in 500g of ethylene glycol butyl ether. 93g of octylamine was added dropwise to the system at 90°C over 30 minutes, and then the temperature was raised to 100°C and the reaction was carried out for 3 hours before the product was discharged.

[0070] Example a2: 1000g of epoxy E20, 300g of epoxy obtained in Example c3, and 10g of epoxy obtained in Example d1 were mixed and dissolved in 560g of ethylene glycol butyl ether. 76.9g of octylamine was added dropwise to the system at 90°C over 30 minutes, and then the temperature was raised to 110°C and the reaction was carried out for 3 hours before the product was discharged.

[0071] Example a3: 1000g of epoxy E06, 150g of epoxy obtained in Example c2, and 10g of epoxy obtained in Example d3 were mixed and dissolved in 300g of ethylene glycol butyl ether. 18.4g of octylamine was added dropwise to the system at 90°C over 30 minutes, and then the temperature was raised to 120°C and the reaction was carried out for 3 hours before the product was discharged.

[0072] Example a4: 1000g of epoxy E06, 200g of epoxy obtained in Example c4, and 10g of epoxy obtained in Example d2 were mixed and dissolved in 810g of ethylene glycol butyl ether. 20.5g of octylamine was added dropwise to the system at 90°C over 30 minutes, and then the temperature was raised to 120°C and the reaction was carried out for 3 hours before the product was discharged.

[0073] Preparation of aqueous one-component epoxy emulsion:

[0074] Example b1: 1803g of the modified epoxy resin obtained in Example a1 was injected into a reactor, and the temperature inside the reactor was maintained at 105°C. Then, a mixture of 6.21g BPO and 155.44g styrene was added dropwise to the reactor over 6 hours for reaction. The temperature was then lowered to 90°C, and 31.09g of 1-(3-aminopropyl)imidazole and 9.33g of dicyandiamide were added and reacted for 1 hour. The temperature was then lowered to 60°C, the dispersion plate was opened, and 1212.5g of water was added within 30 minutes to obtain an aqueous one-component epoxy emulsion.

[0075] Example b2: 1946.9g of the modified epoxy resin obtained in Example a2 was injected into a reactor, and the temperature inside the reactor was maintained at 105°C. Then, a mixture of 55.32g BPO, 442.53g styrene, and 276.58g butyl acrylate was added dropwise to the reactor over 5 hours for reaction. The temperature was then lowered to 80°C, and 27.66g of 1-(3-aminopropyl)imidazole and 5.53g of dicyandiamide were added. The reaction was carried out for 1.5 hours, and then the temperature was lowered to 40°C. The dispersion plate was opened, and 2765.8g of water was added within 30 minutes to obtain an aqueous one-component epoxy emulsion.

[0076] Example b3: 1478.4g of the modified epoxy resin obtained in Example a3 was injected into a reactor, and the temperature inside the reactor was maintained at 110°C. Then, a mixture of 117.44g BPO, 1174.4g styrene, and 587.2g butyl acrylate was added dropwise to the reactor over 5 hours for reaction. The temperature was then lowered to 70°C, and 17.62g of 1-(3-aminopropyl)imidazolium and 3.52g of dicyandiamide were added and reacted for 2 hours. The temperature was then lowered to 30°C, the dispersion plate was opened, and 2525.0g of water was added within 30 minutes to obtain an aqueous one-component epoxy emulsion.

[0077] Example b4: 2040.5g of the modified epoxy resin obtained in Example a4 was injected into a reactor, and the reactor temperature was maintained at 120°C. Then, a mixture of 81.77g BPO and 531.48g butyl acrylate was added dropwise to the reactor over 4 hours for reaction. The temperature was then lowered to 80°C, and 8.18g of 1-(3-aminopropyl)imidazolium and 2.04g of dicyandiamide were added and reacted for 1 hour. The temperature was then lowered to 40°C, the dispersion plate was opened, and 1430.9g of water was added within 30 minutes to obtain an aqueous one-component epoxy emulsion.

[0078] Example b5: 1946.9g of the modified epoxy resin obtained in Example a2 was injected into a reactor, and the temperature inside the reactor was maintained at 105°C. Then, a mixture of 55.32g BPO, 442.53g styrene, and 276.58g butyl acrylate was added dropwise to the reactor over 5 hours for reaction. The temperature was then lowered to 80°C, and 27.66g of 2-imidazole-1-ethylamine and 5.53g of dicyandiamide were added. The reaction was carried out for 1.5 hours, and then the temperature was lowered to 40°C. The dispersion plate was opened, and 2765.8g of water was added within 30 minutes to obtain an aqueous one-component epoxy emulsion.

[0079] Comparative Example b6: 1946.9g of the modified epoxy resin obtained in Example a2 was injected into a reactor, and the temperature inside the reactor was maintained at 105°C. Then, a mixture of 55.32g BPO, 442.53g styrene, and 276.58g butyl acrylate was added dropwise to the reactor over 5 hours for reaction. The temperature was then lowered to 80°C, and 27.66g of 1-(3-aminopropyl)imidazole was added and reacted for 1.5 hours. The temperature was then lowered to 40°C, the dispersion plate was opened, and 2765.8g of water was added within 30 minutes to obtain an aqueous one-component epoxy emulsion.

[0080] Comparative Example b7: 1946.9g of the modified epoxy resin obtained in Example a2 was injected into a reactor, and the reactor temperature was maintained at 105°C. Then, a mixture of 55.32g BPO, 442.53g styrene, and 276.58g butyl acrylate was added dropwise to the reactor over 5 hours for reaction. The temperature was then lowered to 80°C, and 5.53g of dicyandiamide was added and reacted for 1.5 hours. The temperature was then lowered to 40°C, the dispersion plate was opened, and 2765.8g of water was added within 30 minutes to obtain an aqueous one-component epoxy emulsion.

[0081] Comparative Example b8: 1946.9g of the modified epoxy resin obtained in Example a2 was injected into a reactor, and the temperature inside the reactor was maintained at 105°C. Then, a mixture of 55.32g BPO, 442.53g styrene, and 276.58g butyl acrylate was added dropwise to the reactor over 5 hours for reaction. The temperature was then lowered to 40°C, the dispersion plate was opened, and 2765.8g of water was added within 30 minutes to obtain an aqueous one-component epoxy emulsion.

[0082] Comparative Example b9: 1386.9g of epoxy resin E20 and 560g of ethylene glycol butyl ether were mixed and injected into a flask. The temperature inside the flask was maintained at 105℃. 55.32g of BPO, 55.48g of acrylic acid, 277.38g of butyl acrylate, and 388.33g of styrene were mixed and slowly added dropwise into the flask. After reacting at a constant temperature for 4 hours, 68.58g of dimethylethanolamine was added. After reacting at 50℃ for 1 hour, the mixture was transferred to a dispersion cup. The dispersion plate was opened, and 2765.8g of deionized water was added within 30 minutes to obtain an aqueous one-component epoxy emulsion.

[0083] Comparative Example b10: 1946.9g of the modified epoxy resin obtained in Example a2 was injected into the reactor, the temperature inside the reactor was maintained at 40°C, the dispersion plate was opened, and 1390.6g of water was added within 30 minutes to obtain an aqueous single-component epoxy emulsion.

[0084] The formulation of water-based epoxy anti-rust paint is shown in Table 2:

[0085] Table 2 Formulation of water-based epoxy anti-rust paint

[0086] composition supplier mass fraction wt% <![CDATA[H2O]]> 10.0 Dispersant BYK190 BYK Chemical 2.0 pH adjuster AMP-95 Angus 0.2 Defoamer BYK024 BYK Chemical 0.3 Titanium Dioxide R902 DuPont 6.0 Barium sulfate Jiande Chemical 10.0 Zinc phosphate Tri-crystal 8.0 Wollastonite Jiangxi Aote 14.0 Carbon Black FW200 Evonik 0.5 Waterborne one-component epoxy emulsion Examples and Comparative Examples b1-b9 48.0 wetting agent BYK 346 BYK Chemical 0.3 Anti-flash rust agent FA 179 Hemings 0.2 Thickener U905 Wanhua Chemical 0.5 total 100.0

[0087] The water-based epoxy anti-rust paint prepared according to Table 2 was applied to a sanded carbon steel plate with a dry film thickness of 70-80 μm. After leveling at room temperature for 10-15 minutes, it was baked at 80℃ for 30 minutes and cured at 25℃ for 7 days to obtain a cured epoxy film. The neutral salt spray resistance was determined according to GB / T 1771 standard. Within the specified test time (300 h), a score of 5 was defined as follows: no rust or blistering on the blank areas of the plate, and rust and blistering at the scratched areas with a blistering width spread of less than 2 mm. A score of 4 was defined as follows: no rust on the blank areas, slight blistering, and rust and blistering at the scratched areas with a blistering width spread of less than 2 mm. A score of 3 was defined as follows: rust on the blank areas, blistering, and rust and blistering at the scratched areas with a blistering width spread of less than 2 mm. The test results are shown in Table 3.

[0088] Table 3 Performance Tests of Waterborne Epoxy Anti-rust Paint

[0089]

[0090] As can be seen from the above performance, the single-component waterborne epoxy emulsion obtained by introducing imidazole groups and dicyandiamide has good stability, and the paint film obtained by combining zinc ions with anti-rust pigments and fillers has good salt spray resistance and good self-healing properties.

Claims

1. An aqueous one-component epoxy emulsion comprising the following components: water, anionic and nonionic modified epoxy resin, styrene monomer and / or acrylate monomer, free radical polymerization initiator, amine-containing imidazole and dicyandiamide, and optionally a solvent; wherein the anionic and nonionic modified epoxy resin molecule contains an ethoxy segment and at least one sulfonate group.

2. The aqueous single-component epoxy emulsion according to claim 1, comprising the following components: by mass parts: 30-60 parts water 15-55 parts of anionic and nonionic modified epoxy resin. 5-40 parts of styrene monomer and / or acrylate monomer, 0.2-3 parts of free radical polymerization initiator, 0.1-2 parts of an amino-containing imidazole. Dicyandiamide 0.02-0.5 parts, Solvent: 0-20 parts.

3. The aqueous one-component epoxy emulsion according to claim 1, comprising the following components: by mass parts: 35-50 parts water 20-45 parts of anionic and nonionic modified epoxy resin. 5-30 parts of styrene monomer and / or acrylate monomer, 0.5-2 parts of free radical polymerization initiator, 0.2-1 part of an amino-containing imidazole. Dicyandiamide 0.05-0.3 parts, Solvent 5-20 parts.

4. The aqueous single-component epoxy emulsion according to claim 1, characterized in that, The anionic and nonionic modified epoxy resin is obtained by reacting an amine containing a primary amine group with epoxy resin A, wherein the molar ratio of the primary amine group to the epoxy group is 1:6-2:5, and the reaction temperature is 100-120℃.

5. The aqueous single-component epoxy emulsion according to claim 4, characterized in that, The molar ratio of the primary amine group to the epoxy group is 1:5 to 1:

3.

6. The aqueous single-component epoxy emulsion according to claim 4, characterized in that, The epoxy resin A comprises the following components: Epoxy resin B containing at least two epoxy groups and having an epoxy value of 0.03-0.55; Epoxy resin C containing at least one epoxy group and an EO segment; Epoxy resin D, obtained by reacting epoxy resin B with aminosulfonate, contains at least one epoxy group.

7. The aqueous one-component epoxy emulsion according to claim 6, characterized in that, The preparation method of the epoxy resin C includes the following steps: esterifying a polyether containing at least 5 ethoxy segments with an acid anhydride to obtain intermediate product C-1, and then reacting it with epoxy resin B in a ring-opening reaction to obtain the epoxy resin C; the structural formula of the polyether is as follows: ; Wherein, R represents H or an alkyl group with 1-12 carbon atoms, R1 represents a hydrogen atom or a methyl group, and the number average molecular weight of the polyether is 300-10000.

8. The aqueous single-component epoxy emulsion according to claim 7, characterized in that, R represents H, methyl, or ethyl, and the number average molecular weight of polyether is 500-6000.

9. The aqueous single-component epoxy emulsion according to claim 6, characterized in that, In the epoxy resin D, the molar ratio of the total amount of epoxy groups provided by the epoxy resin B to the total amount of active hydrogen contained in the amino group of the aminosulfonate is 2:1-4:

1.

10. The aqueous one-component epoxy emulsion according to claim 1, characterized in that, The styrene monomer and / or acrylate monomer are one or more of styrene, methyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and isobornyl methacrylate.

11. The aqueous one-component epoxy emulsion according to claim 1, characterized in that, The amino-containing imidazole is one or more of 2-(4-methyl-1H-imidazol-5-yl)ethylamine, 1-(4-aminobenzyl)-1H-imidazol, 1-methyl-5-aminomethylimidazol, 1-(3-aminopropyl)imidazol, and 2-imidazol-1-ethylamine.

12. A method for preparing the aqueous one-component epoxy emulsion according to any one of claims 1-11, comprising the following steps: According to the proportion, add anionic and nonionic modified epoxy resin and solvent to the reactor, heat to 100-120℃, and wait for the system to become a homogeneous liquid. Add a mixture of styrene monomer and / or acrylate monomer and free radical polymerization initiator dropwise over 3-8 hours. Then cool down to 60-90℃, add imidazole and dicyandiamide containing amine groups, react for 1-3 hours, and then add water at 30-80℃ to disperse at high speed into an aqueous single-component epoxy emulsion.

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