Anionic epoxy emulsifier, preparation method thereof and epoxy resin aqueous dispersion

Abstract

The invention provides an anionic epoxy emulsifier, a preparation method thereof and an epoxy resin aqueous dispersion, the anionic epoxy emulsifier contains at least one epoxy group from epoxy resin and at least one sulfonate group from carboxyl sulfonate. The anionic epoxy emulsifier provided by the invention is excellent in emulsifying property, is used for an epoxy resin aqueous dispersion, can maintain the stability of the epoxy resin aqueous dispersion under the condition of a small dosage, and has good corrosion resistance after the epoxy resin aqueous dispersion is cured.

Description

Technical Field

[0001] The invention relates to the field of waterborne epoxy coatings, and in particular to an anionic epoxy emulsifier and a preparation method thereof, and an epoxy resin aqueous dispersion. Background Art

[0002] Epoxy resin has excellent adhesion, corrosion resistance, electrical insulation and physical mechanical properties, and is widely used in various aspects from daily life to high-tech fields. Traditional epoxy resin coatings are generally solvent-based, and most of the organic volatiles in them are flammable, explosive and toxic substances, which are directly discharged into the atmosphere, endangering human health and the ecological environment.

[0003] Water-based epoxy emulsion (epoxy resin aqueous dispersion) generally refers to an emulsion or aqueous dispersion formed by epoxy resin dispersed in water in the form of particles, droplets or colloids. Compared with using organic solvents to dissolve epoxy resin, water-based epoxy emulsions that use water as a solvent to dissolve epoxy resin are more environmentally friendly, easier to clean, and safer to store, transport and use.

[0004] It is known that water-based epoxy emulsions are prepared using traditional non-ionic emulsifiers, mixers, ball mills and other equipment through phase inversion, mechanical grinding and other methods. However, since traditional non-ionic emulsifiers have low emulsification properties, the amount of emulsifier used in the emulsion is large, resulting in an unstable emulsion system, easy aggregation and precipitation of latex particles, and a short storage time. Summary of the invention

[0005] The invention provides an anionic epoxy emulsifier, which has excellent emulsification property and can be used for epoxy resin water dispersion to maintain its stability at a relatively low dosage.

[0006] The present invention also provides a method for preparing anionic epoxy emulsifier, which can prepare the anionic epoxy emulsifier and has a simple process flow.

[0007] The present invention also provides an epoxy resin aqueous dispersion. Since the epoxy resin aqueous dispersion includes the anionic epoxy emulsifier, it has the advantages of good stability and long storage time.

[0008] In a first aspect, the present invention provides an anionic epoxy emulsifier comprising at least one epoxy group derived from an epoxy resin and at least one sulfonate group derived from a carboxysulfonate.

[0009] Furthermore, the molar ratio of the epoxy group of the epoxy resin to the carboxyl group of the carboxyl sulfonic acid is at least 2:1; preferably 2.5-4:1.

[0010] Furthermore, the epoxy resin contains at least two epoxy groups in its molecular structure. Preferably, the epoxy value of the epoxy resin is not greater than 0.6, and more preferably not greater than 0.55.

[0011] In a second aspect, the present invention provides a method for preparing the above-mentioned anionic epoxy emulsifier, comprising the following steps:

[0012] A mixture containing epoxy resin, carboxyl sulfonate and a catalyst is subjected to a ring-opening reaction to obtain the anionic epoxy emulsifier.

[0013] Furthermore, the viscosity of the mixed material is 200-10000cp.

[0014] Furthermore, the reaction temperature of the ring-opening reaction is 100°C-150°C; preferably 120°C-140°C.

[0015] In a third aspect, the present invention provides an epoxy resin aqueous dispersion, comprising water, and the anionic epoxy emulsifier described in the first aspect or the anionic epoxy emulsifier prepared by the preparation method described in the second aspect.

[0016] Further, it also includes at least one nonionic active emulsifier;

[0017] Preferably, the molecular structure of the nonionic active emulsifier contains at least 10 ethoxy segments and at least 1 epoxy group;

[0018] More preferably, in the nonionic active emulsifier, the content of ethoxy segments is 40wt%-95wt%, preferably 60wt%-85wt%.

[0019] Preferably, the nonionic reactive emulsifier accounts for 3wt%-20wt% of the solid mass in the epoxy resin aqueous dispersion, preferably 8wt%-12wt%.

[0020] Furthermore, the total mass of the sulfonate groups of the anionic epoxy emulsifier accounts for 0.1 wt%-1 wt%, preferably 0.2 wt%-0.5 wt%, of the solid mass in the epoxy resin aqueous dispersion.

[0021] The anionic epoxy emulsifier provided by the present invention has good emulsification performance and can be used for epoxy resin aqueous dispersion to maintain its stability at a relatively low dosage.

[0022] Furthermore, the anionic epoxy emulsifier prepared by the preparation method provided by the present invention does not contain a structure that can catalyze the epoxy ring-opening reaction, such as a tertiary amine or a group that makes the emulsion exhibit alkalinity or acidity. Therefore, the anionic epoxy emulsifier and the epoxy resin aqueous dispersion containing the anionic epoxy emulsifier have excellent stability. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific implementation methods listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0024] In view of the problems that the current epoxy emulsifier has low emulsification and large dosage, resulting in instability of the epoxy resin aqueous dispersion system and short storage time, the present invention finds that a hydrophilic group can be introduced into the anionic epoxy emulsifier, and its hydrophilicity is used to improve the water solubility and emulsification performance of the anionic epoxy emulsifier, which helps to form a relatively stable epoxy resin aqueous dispersion in the aqueous phase. However, the inventors further found that the introduced hydrophilic group will produce groups that make the emulsion exhibit alkalinity or acidity after reacting with the epoxy resin. These groups will further catalyze the epoxy ring-opening reaction, making it difficult for the epoxy resin aqueous dispersion to maintain its stability for a long time. Therefore, the present invention envisions solving the above problems by changing the composition of the emulsifier and inhibiting the ring opening:

[0025] In a first aspect, the present invention provides an anionic epoxy emulsifier comprising at least one epoxy group derived from an epoxy resin and at least one sulfonate group derived from a carboxysulfonate.

[0026] The present invention introduces carboxyl sulfonate and epoxy group of epoxy resin into anionic epoxy emulsifier to generate carboxylate structure, which will not further catalyze epoxy ring-opening reaction, and the structure usually has good water resistance and chemical stability. Therefore, the presence of carboxylate can improve the long-term stable dispersion of ionic epoxy emulsifier; in addition, since sulfonate group is a strong hydrophilic group, it can improve the water solubility and emulsification performance of ionic epoxy emulsifier, which is helpful to form a more stable epoxy resin aqueous dispersion in the water phase.

[0027] In the present invention, the carboxyl sulfonate has a molecular structure of the following general formula (I), wherein R is a substituted or unsubstituted organic carbon chain, the organic carbon chain can be a straight carbon chain, a cyclic carbon chain or an aromatic group, and M is preferably a monovalent metal ion such as sodium and potassium.

[0028] Formula (I).

[0029] In one embodiment, the carboxyl sulfonate is prepared by neutralizing carboxyl sulfonic acid with an alkali, and the degree of neutralization is preferably 90% to 98%.

[0030] In one embodiment, the molar ratio of the epoxy groups of the epoxy resin to the carboxyl groups of the carboxyl sulfonate is at least 2:1; preferably 2.5-4:1.

[0031] The present invention controls the molar ratio of the total amount of epoxy groups provided by the epoxy resin to the total amount of carboxyl groups of the carboxyl sulfonate in the reaction system of the ionic reactive emulsifier, so that the reaction product contains the anionic epoxy emulsifier of the present invention having at least one epoxy group derived from the epoxy resin and at least one sulfonate group derived from the carboxyl sulfonate in the molecule.

[0032] Since the epoxy value affects the stability of the anionic epoxy emulsion when preparing the anionic epoxy emulsion, a resin with a high epoxy value may be more likely to form a stable emulsion, however, an excessively high epoxy value may increase the viscosity of the emulsion, affecting its fluidity and processing properties. Therefore, in some embodiments, the epoxy resin contains at least two epoxy groups in its molecular structure, and preferably, the epoxy value of the epoxy resin is not greater than 0.6, and more preferably not greater than 0.55.

[0033] It can be understood that the above-mentioned epoxy resin molecules contain at least two epoxy groups. These epoxy resins can be saturated or unsaturated aliphatic, cycloaliphatic, aromatic or heterocyclic epoxy resins, etc. Furthermore, the epoxy resin molecules also contain hydroxyl groups and / or other substituents that do not cause interfering side reactions under mixing and reaction conditions, such as: alkyl or aromatic substituents, ether groups, etc.

[0034] In one embodiment, the epoxy resin is a polyglycidyl ether. More specifically, the polyglycidyl ether epoxy resin can be a glycidyl ether of a polyphenol or a glycidyl ether of a polyol or a polyglycidyl ester of a polycarboxylic acid, wherein the glycidyl ether of a polyphenol includes but is not limited to: resorcinol, hydroquinone, 2,2-bis(4′-hydroxyphenyl)propane (bisphenol A), an isomer mixture of 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 the chlorination and bromination products of the aforementioned compounds; the glycidyl ethers of polyols are not limited to: ethylene glycol-1,2-diglycidyl ether, propylene glycol-1,2-diglycidyl ether, propylene glycol-1,3-diglycidyl ether, butanediol diglycidyl ether, pentanediol diglycidyl ether, neopentyl glycol diglycidyl ether, hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether , high-carbon polyoxyalkylene glycol diglycidyl ether (such as high-carbon polyoxyethylene glycol diglycidyl ether and polyoxypropylene glycol diglycidyl ether, mixed polyoxyethylene-propylene glycol diglycidyl ether), polyoxybutylene glycol diglycidyl ether, glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, polyglycidyl ether of sorbitol, alkoxylated polyols such as glycerol, trimethylolpropane, polyglycidyl ether of pentaerythritol, cyclohexanedimethanol, diglycidyl ether of bis(4-hydroxycyclohexyl)methane and 2,2-bis(4-hydroxycyclohexyl)propane, polyglycidyl ether of castor oil or triglycidyl tri(2-hydroxyethyl)isocyanurate, etc.

[0035] For example, polyglycidyl esters of polycarboxylic acids can be prepared by the reaction of 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-naphthalene dicarboxylic acid and diglycidyl esters of higher dicarboxylic acids, dimerized or trimerized linolenic acid).

[0036] In a second aspect, the present invention provides a method for preparing the above-mentioned anionic epoxy emulsifier, comprising the following steps:

[0037] A mixture containing epoxy resin, carboxyl sulfonate and a catalyst is subjected to a ring-opening reaction to obtain the anionic epoxy emulsifier.

[0038] The anionic epoxy emulsifier prepared by the preparation method provided by the present invention does not contain a structure that can catalyze the epoxy ring-opening reaction, such as a tertiary amine or a group that makes the emulsion exhibit alkalinity or acidity, thereby significantly improving the stability of the anionic epoxy emulsifier and the prepared epoxy resin aqueous dispersion.

[0039] The preparation method of the above-mentioned mixed material is not particularly limited in the present invention, and the technicians can prepare the mixed material according to the actual situation. In some embodiments, the epoxy resin, carboxyl sulfonate and catalyst are added to a mixing container at the same time, and then a solvent that can dissolve the carboxyl sulfonate is added, and the mixed material is obtained by mixing; in other embodiments, the carboxyl sulfonate is first dissolved in water, and then the epoxy resin and the catalyst are added, and the mixed material is obtained by mixing. Furthermore, in order to ensure that the carboxyl sulfonate is completely dissolved in water, thereby ensuring the smooth progress of the ring-opening reaction, in a specific embodiment, the mass ratio of the water to the first reaction raw material is not less than 1:20, preferably not less than 1:10, and more preferably not less than 1:5.

[0040] In order to further ensure the uniformity of the reaction and thus improve the emulsification of the anionic epoxy emulsifier, in one embodiment, the viscosity of the mixture is 200-10000 cp.

[0041] It is understood that the viscosity of the mixed material can be achieved by adding a solvent. The solvent is a liquid organic substance commonly used in the art that can be adjusted to reduce the viscosity of the reaction system, for example, propylene glycol methyl ether, ethylene glycol butyl ether, dipropylene glycol dimethyl ether, acetone, butanone or butanol.

[0042] The catalyst for the above-mentioned ring-opening reaction is a catalyst well known in the art, for example, one or more of triphenylphosphine, triphenylphosphine, and boron trifluoride etherate, and its amount can be more than 0.04wt% of the total solid content in the reaction system, preferably 0.05wt%-1wt%, such as 0.1wt%, 0.2wt%, 0.5wt% or 0.8wt%, etc.

[0043] In order to increase the reaction rate, the ring-opening reaction may be carried out at a certain temperature. In one embodiment, the reaction temperature of the ring-opening reaction is 100°C-150°C; preferably 120°C-140°C.

[0044] The reaction time of the ring-opening reaction can be adjusted according to the total amount of the added materials. For example, in one embodiment, the reaction time of the ring-opening reaction is 2-5 h, more preferably 3-4 h.

[0045] In a third aspect, the present invention provides an epoxy resin aqueous dispersion, comprising water, and the anionic epoxy emulsifier described in the first aspect or the anionic epoxy emulsifier prepared by the preparation method described in the second aspect.

[0046] In one embodiment, at least one nonionic active emulsifier is also included. The above embodiment can provide stronger emulsification ability by using nonionic and ionic emulsifiers together. The nonionic emulsifier acts through hydrogen bonds and van der Waals forces, while the ionic emulsifier stabilizes the epoxy resin aqueous dispersion through electrostatic interaction. The combination of the two can more effectively reduce the interfacial tension and form a more stable epoxy resin aqueous dispersion.

[0047] In one embodiment, the molecular structure of the nonionic reactive emulsifier contains at least 10 ethoxy segments and at least 1 epoxy group.

[0048] The ethoxy (-CH2CH2O-) segment is hydrophilic and can improve the water solubility of the emulsifier, which enables the emulsifier to be better dispersed in the aqueous phase, thereby stabilizing the oil-water emulsion; and the above-mentioned embodiment stipulates that the segment containing at least 10 ethoxy units in the non-ionic active emulsifier can provide sufficient hydrophilicity, making it suitable for the use of non-ionic active emulsifiers in applications requiring high water solubility; and the epoxy group is a reactive site that can react with other chemical substances (such as curing agents or cross-linking agents). Due to the presence of the epoxy group, the non-ionic active emulsifier can react with other components during the emulsification process to form a more stable network structure.

[0049] In nonionic reactive emulsifiers, a high content of ethoxy segments helps to form a stable emulsion, while in corrosion-resistant coatings or adhesives, a balanced amount of ethoxy segments is required to obtain optimal durability. Therefore, in one embodiment, the content of ethoxy segments in the nonionic reactive emulsifier is 40wt%-95wt%, preferably 60wt%-85wt%.

[0050] Nonionic active emulsifiers usually stabilize emulsions through hydrogen bonds and van der Waals forces, and are not charged, so they show good stability under different pH conditions; while ionic emulsifiers stabilize emulsions through electrostatic interactions, have charges (mainly provided by sulfonates), and show good stability within a specific pH range. By adjusting the proportion of the two in the epoxy resin aqueous dispersion, the interfacial tension and particle stability of the emulsion can be optimized. In one embodiment, the nonionic active emulsifier accounts for 3wt%-20wt% of the solid mass in the epoxy resin aqueous dispersion, preferably 8wt%-12wt%.

[0051] Among them, the sulfonate group is a strong hydrophilic group, and an increase in its content usually improves the water solubility and emulsification properties of the epoxy emulsion. This helps to form a more stable epoxy resin aqueous dispersion in the water phase, but the sulfonate group accounts for too high a solid mass in the epoxy resin aqueous dispersion, which may cause the epoxy resin aqueous dispersion to be too hydrophilic after curing, which is not conducive to the corrosion resistance of the paint film. Therefore, in order to balance the dispersibility, stability and corrosion resistance of the epoxy resin aqueous dispersion after curing, in some embodiments, the total mass of the sulfonic acid group and the sulfonate group of the anionic epoxy emulsifier accounts for 0.1wt%-1wt% of the solid mass in the epoxy resin aqueous dispersion, preferably 0.2wt%-0.5wt%.

[0052] It is understood that the solid mass in the epoxy resin aqueous dispersion refers to the solid content of the epoxy resin aqueous dispersion, that is, the sum of the masses of the components other than the liquid. In one embodiment, the nonionic epoxy reactive emulsifier is prepared by the following method: a polyether-anhydride product having at least one carboxyl group in the molecule and an epoxy resin having two or more epoxy groups in the molecule are mixed, and the carboxyl group of the polyether-anhydride product is subjected to a ring-opening reaction with the epoxy group of the epoxy resin to obtain the nonionic reactive emulsifier.

[0053] The nonionic epoxy reactive emulsifier molecule contains at least one epoxy group from an epoxy resin. The molar ratio of the total amount of epoxy groups provided by the epoxy resin in the reaction system to the total amount of carboxyl groups contained in the polyether-anhydride product is at least 1:1, such as 2:1, 5:1, 10:1 or higher. The epoxy resin can be one or more of the epoxy resins mentioned above.

[0054] In one embodiment, the reaction conditions of the above ring-opening reaction can be: reacting at 40-140° C., preferably 120-140° C., for 1-5 h, preferably 1-3 h, under the action of a catalyst.

[0055] The catalyst for the above-mentioned ring-opening reaction is well known in the art, for example, one or more of triphenylphosphine, triphenylphosphine, and boron trifluoride etherate, and the amount thereof can be more than 0.04wt% of the total solid content in the reaction system, preferably 0.05wt%-1wt%, such as 0.1wt%, 0.2wt%, 0.5wt% or 0.8wt%; the above-mentioned polyether-anhydride product is obtained by esterifying the polyether with the anhydride of a polycarboxylic acid having 2-4 carboxyl groups in the molecule.

[0056] Exemplarily, the initiator used to prepare the above polyether can be: saturated monohydric alcohols, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, isomeric amyl alcohols, hexanols, octanols, nonyl alcohols, n-decanols, n-dodecyl alcohols, n-tetradecanols, n-hexadecanols, cyclohexanols, hydroxymethylcyclohexane and 3-ethyl-3-hydroxymethyloxetane; unsaturated alcohols, for example, allyl alcohol, 1,1-dimethyl-allyl alcohol, alcohol or oleyl alcohol; aromatic alcohols, such as phenol, isomeric cresols or methoxyphenols, etc.; aromatic aliphatic alcohols, such as benzyl alcohol, anisyl alcohol or cinnamyl alcohol; secondary monoamines, such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, di-n-butylamine, diisobutylamine, bis(2-ethylhexyl)amine, N-methyl- and N-ethyl-cyclohexylamine or dicyclohexylamine, etc.; heterocyclic secondary amines, such as morpholine, pyrrolidine, piperidineethylpyrazole, etc. Preferred initiators are saturated monohydric alcohols having up to 4 carbon atoms, with methanol being particularly preferred as initiator.

[0057] The polymerization units used to prepare the above-mentioned polyether can be one or both of propylene oxide and ethylene oxide, wherein the amount of ethylene oxide used is at least 50 mol%, preferably at least 80 mol%, based on the total molar amount of the polymerization units; the number average molecular weight of the prepared polyether can be 300-8000, preferably 500-6000, and the number of ethoxy units can be 10-300, preferably 10-150.

[0058] Exemplarily, the acid anhydride is an anhydride of a polycarboxylic acid having 2-4 carboxyl groups in the molecule, preferably an anhydride obtained by intramolecular dehydration of a polycarboxylic acid having 2-3 carboxyl groups, for example, anhydrides from aromatic polycarboxylic acids or cyclic aliphatic polycarboxylic acids, etc., preferably anhydrides from aromatic polycarboxylic acids. As anhydrides of aromatic polycarboxylic acids, for example, hexahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone-3,3',4,4'-tetracarboxylic anhydride, etc. can be listed, among which hexahydrophthalic anhydride and trimellitic anhydride are preferred. In addition, as anhydrides of cyclic aliphatic polycarboxylic acids, for example, hydrogenated trimellitic anhydride, hydrogenated pyromellitic anhydride, etc. can be listed.

[0059] When the esterification reaction is carried out, the ratio of the total amount of the anhydride groups (-COOCO-) of the acid anhydride to the total amount of the hydroxyl groups of the polyether is 1 to 1.2, and more preferably 1.0 to 1.1. When the ratio of the total amount of the anhydride groups (-COOCO-) of the acid anhydride to the total amount of the hydroxyl groups of the polyether is less than 1, hydroxyl groups will remain in the water-dispersible epoxy resin. In addition, the reaction temperature of the esterification reaction can be 40 to 140°C, preferably 80 to 130°C;

[0060] The reaction time of the esterification reaction can be 1-5 hours, preferably 1-3 hours. In the esterification reaction, a catalyst and / or solvent known in the art can also be used as needed.

[0061] Those skilled in the art understand that, in addition to emulsifiers, epoxy resins and water, other additives are usually added to the dispersion, such as epoxy reactive diluents (added in an amount of 0-20% of the dispersion), for example, C8-C14 glycidyl ether compositions, phenyl glycidyl ether, butyl glycidyl ether; solvents (added in an amount of 0-20 wt % of the dispersion), for example, propylene glycol methyl ether (PMOP), ethylene glycol butyl ether, dipropylene glycol dimethyl ether, acetone, butanone, butanol, etc.; thickeners (added in an amount of 0-5 wt % of the dispersion), for example, U905, U300, etc.; defoamers (added in an amount of 0-1 wt % of the dispersion), for example, foamstar 2410, 902w, BYK-024, -033, -028, A1001, etc., and other commonly used additives.

[0062] In one embodiment, the epoxy resin dispersion is prepared as follows: the nonionic epoxy reactive emulsifier, the ionic epoxy reactive emulsifier and optionally other auxiliary agents are added to the epoxy resin in a desired ratio, and water is added to disperse them to form an epoxy resin aqueous dispersion.

[0063] In order to further understand the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. 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.

[0064] Unless otherwise specified, the reagents involved in the embodiments of the present invention are all commercially available products and can be purchased through commercial channels.

[0065] <Source of reaction raw materials>

[0066] Some of the raw materials and information used in the following experiments are shown in Table 1.

[0067] Table 1:

[0068]

[0069] <Test Method>

[0070] The pendulum hardness refers to GB / T 1730 "Paint film hardness determination method pendulum damping test";

[0071] Adhesion refers to GB / T 9286 "Scratch test for paint and varnish films";

[0072] Water resistance refers to GB / T 1733 "Determination of water resistance of paint films";

[0073] Salt spray resistance refers to GB / T 1765 "Paint film preparation method for determining resistance to moisture and heat, salt spray and weathering (artificial acceleration)";

[0074] 30-day thermal storage stability test: The sample to be tested is placed in a 50°C constant temperature oven to test whether stratification occurs for 30 days;

[0075] Test of average particle size: Dynamic light scattering (DLS) was used to measure the particle size and particle size distribution of the waterborne polyurethane dispersion to be tested. In the test, the Zetasizer Nano ZS90 particle size analyzer of Malvern was used to measure the particle size and particle size distribution of the emulsion. The test temperature was 25°C, the laser angle was 90°, and the test laser wavelength was 633nm.

[0076] <Preparation of anionic epoxy emulsifier>

[0077] Example 1a:

[0078] Provided is an anionic epoxy emulsifier, comprising at least one epoxy group from an epoxy resin and at least one sulfonate group from a first reaction raw material; the molar ratio of the epoxy group of the epoxy resin to the carboxyl group in the first reaction raw material is 2.5:1;

[0079] The preparation method thereof comprises the following steps:

[0080] 1200g of epoxy resin E20 and 100g of propylene glycol methyl ether were injected into the kettle, and stirring was started. The temperature in the reactor was raised to 100°C. After the epoxy resin was dissolved, 112g of a 20wt% sodium 3-carboxybenzenesulfonate aqueous solution and 0.4g of a triphenylphosphine catalyst were added into the reactor. The viscosity of the mixed system was 10000cp. The temperature in the reactor was maintained at 100°C and the reaction was carried out for 5h. The acid value was sampled and tested until it reached the theoretical value (determined by NaOH back titration, the same below). The product was anionic epoxy emulsifier a1.

[0081] Example 2a:

[0082] Provided is an anionic epoxy emulsifier, comprising at least one epoxy group from an epoxy resin and at least one sulfonate group from a first reaction raw material; the molar ratio of the epoxy group of the epoxy resin to the carboxyl group in the first reaction raw material is 2:1;

[0083] The preparation method thereof comprises the following steps:

[0084] 137g of epoxy resin E44 and 100g of propylene glycol methyl ether were injected into the kettle, stirring was started, and the temperature in the reactor was raised to 100°C. After the epoxy resin was dissolved, 487g of 15wt% sodium 3-carboxybenzenesulfonate aqueous solution and 0.5g of triphenylphosphine catalyst were added into the reactor. The viscosity of the mixed system was 200cp. The temperature in the reactor was maintained at 120°C. The reaction was continued for 3h. The sample was taken for testing and the acid value reached the theoretical value before the material was discharged. The product was anionic epoxy emulsifier a2.

[0085] Example 3a:

[0086] Provided is an anionic epoxy emulsifier, comprising at least one epoxy group from an epoxy resin and at least one sulfonate group from a first reaction raw material; the molar ratio of the epoxy group of the epoxy resin to the carboxyl group in the first reaction raw material is 3:1;

[0087] The preparation method thereof comprises the following steps:

[0088] 220g of epoxy resin E20 and 100g of propylene glycol methyl ether were injected into the kettle, stirring was started, and the temperature in the reactor was raised to 100°C. After the epoxy resin was dissolved, 158g of 5-sulfosalicylic acid aqueous solution with a solid content of 20wt% and 0.5g of tetrabutylammonium bromide catalyst were added into the reactor. The viscosity of the mixed system was 3000cp. The temperature in the reactor was raised to 150°C, and the reaction was continued for 2h. The sample was taken for testing and the acid value reached the theoretical value before the material was discharged. The product was anionic epoxy emulsifier a3.

[0089] Comparative Example 1a':

[0090] Provided is an anionic epoxy emulsifier, comprising at least one epoxy group from an epoxy resin and at least one sulfonate group from a first reaction raw material; the molar ratio of the epoxy group of the epoxy resin to the carboxyl group in the first reaction raw material is 2.5:1;

[0091] The preparation method thereof comprises the following steps:

[0092] 120g of epoxy resin E20 and 100g of propylene glycol methyl ether were injected into the kettle, stirring was started, and the temperature in the reactor was raised to 100°C. After the epoxy resin was dissolved, 121g of sodium cyclohexylaminopropane sulfonate with a solid content of 20wt% was added. water The solution and 0.5g triphenylphosphine catalyst were added into the reactor, the temperature in the reactor was maintained at 100℃, the reaction was continued for 3h, and the sample was taken for testing. When the acid value reached the theoretical value (determined by NaOH back titration, the same below), the product was discharged. The product was anionic epoxy emulsifier a1'.

[0093] <Preparation of nonionic epoxy reactive emulsifier>

[0094] Embodiment 1b:

[0095] Provided is a non-anionic epoxy emulsifier, and a preparation method thereof, comprising the following steps:

[0096] 1000 g of polyethylene glycol (molecular weight 6000) after melt dehydration was injected into the kettle, and the temperature in the kettle was maintained at 80°C. Then 53 g of hexahydrophthalic anhydride was added into the reactor, and the temperature was raised to 100°C. The reaction was carried out for about 3 hours. After the acid value reached the theoretical value (determined by NaOH back titration, the same below), 210 g of epoxy resin E20 was injected, and after stirring evenly, 2.5 g of triphenylphosphine (TPP) catalyst was added. The reaction was carried out at a constant temperature of 140°C for 3 hours. The product was anionic epoxy emulsifier b1, in which the content of ethoxy units bonded to the polyether chain in the product was 80 wt%.

[0097] Example 2b:

[0098] Provided is a non-anionic epoxy emulsifier, and a preparation method thereof, comprising the following steps:

[0099] 1000 g of polyethylene glycol monomethyl ether (molecular weight 3000) after melt dehydration was injected into the kettle, and the temperature in the kettle was maintained at 80°C. Then 64 g of trimellitic anhydride was added into the reactor, and the temperature was raised to 120°C. The reaction was carried out for about 2 hours. After sampling and testing the acid value to reach the theoretical value (determined by NaOH back titration, the same below), 400 g of epoxy resin E44 was injected, and after stirring evenly, 2 g of triphenylphosphine (TPP) catalyst was added. The reaction was carried out at a constant temperature of 120°C for 3 hours. The acid value was tested and the material was discharged after reaching the theoretical value. The product is anionic epoxy emulsifier b2, in which the content of ethoxy units bonded to the polyether chain in the product is 70%.

[0100] <Preparation of Epoxy Resin Dispersion>

[0101] Example C1:

[0102] Provided is an epoxy resin aqueous dispersion, comprising an anionic epoxy emulsifier a1 and a non-anionic epoxy emulsifier b1, wherein the total mass of sulfonic acid groups and sulfonate groups of the anionic epoxy emulsifier accounts for 0.2wt% of the solid mass in the epoxy resin aqueous dispersion, and the non-ionic reactive emulsifier accounts for 10wt% of the solid mass in the epoxy resin aqueous dispersion.

[0103] The preparation method thereof comprises the following steps:

[0104] 400 g of epoxy resin E51, 40 g of propylene glycol methyl ether, 25 g of anionic epoxy emulsifier a1, and 46 g of nonionic epoxy reactive emulsifier b1 were added into a dispersion kettle, and the mixture was stirred to form a uniform and stable resin component; the temperature in the kettle was raised to 50°C, and 378 g of deionized water was gradually dripped into the above resin component through a peristaltic pump, and the dripping time lasted for 30 min. After the water was dripped, the system was cooled to 35°C and the material was discharged. The obtained epoxy resin aqueous dispersion was C1, with a solid content of 50 wt %, and an average particle size of the solid particles of 350 nm.

[0105] Example C2:

[0106] Provided is an epoxy resin aqueous dispersion, comprising an anionic epoxy emulsifier a2 and a non-anionic epoxy emulsifier b1, wherein the total mass of sulfonic acid groups and sulfonate groups of the anionic epoxy emulsifier accounts for 0.1wt% of the solid mass in the epoxy resin aqueous dispersion, and the non-ionic reactive emulsifier accounts for 12wt% of the solid mass in the epoxy resin aqueous dispersion.

[0107] The preparation method thereof comprises the following steps:

[0108] Add 400g of epoxy resin E20, 63g of propylene glycol methyl ether, 20g of anionic epoxy emulsifier a2, and 60g of nonionic epoxy active emulsifier b1 into a dispersion kettle, stir and mix to form a uniform and stable resin component; the temperature in the kettle is raised to 55°C, and 420g of deionized water is gradually dripped into the above resin component through a peristaltic pump. The dripping time lasts for 30min. After the water is dripped, the system is cooled to 35°C and the material is discharged. The obtained epoxy resin aqueous dispersion is C2, with a solid content of 53wt% and an average particle size of the solid particles of 500nm.

[0109] Example C3:

[0110] Provided is an epoxy resin aqueous dispersion, comprising an anionic epoxy emulsifier a3 and a non-anionic epoxy emulsifier b1, wherein the total mass of sulfonic acid groups and sulfonate groups of the anionic epoxy emulsifier accounts for 1wt% of the solid mass in the epoxy resin aqueous dispersion, and the non-ionic reactive emulsifier accounts for 9wt% of the solid mass in the epoxy resin aqueous dispersion.

[0111] The preparation method thereof comprises the following steps:

[0112] Add 400g of epoxy resin E44, 50g of propylene glycol methyl ether, 150g of anionic epoxy emulsifier a3, and 50g of nonionic epoxy active emulsifier b1 into a dispersion kettle, stir and mix to form a uniform and stable resin component; the temperature in the kettle is raised to 45°C, and 400g of deionized water is gradually dripped into the above resin component through a peristaltic pump, and the dripping time lasts for 30min. After the water dripping is completed, the system is cooled to 35°C and discharged. The obtained epoxy resin aqueous dispersion is C3, with a solid content of 50wt% and an average particle size of solid particles of 320nm.

[0113] Example C4:

[0114] Provided is an epoxy resin aqueous dispersion, comprising an anionic epoxy emulsifier a1 and a non-anionic epoxy emulsifier b2, wherein the total mass of sulfonic acid groups and sulfonate groups of the anionic epoxy emulsifier accounts for 0.4wt% of the solid mass in the epoxy resin aqueous dispersion, and the non-ionic reactive emulsifier accounts for 8wt% of the solid mass in the epoxy resin aqueous dispersion.

[0115] The preparation method thereof comprises the following steps:

[0116] 400 g of epoxy resin E20, 100 g of propylene glycol methyl ether, 80 g of anionic epoxy emulsifier a1, and 38 g of nonionic epoxy active emulsifier b2 were added into a dispersion kettle, and the mixture was stirred to form a uniform and stable resin component; the temperature in the kettle was raised to 45°C, and 478 g of deionized water was gradually dripped into the above resin component through a peristaltic pump, and the dripping time lasted for 30 min. After the water was dripped, the system was cooled to 35°C and the material was discharged. The obtained epoxy resin aqueous dispersion was C3, with a solid content of 50 wt %, and an average particle size of the solid particles of 420 nm.

[0117] Comparative Example C1':

[0118] Provided is an epoxy resin aqueous dispersion, comprising a non-anionic epoxy emulsifier b1.

[0119] The preparation method thereof comprises the following steps:

[0120] Add 400g of epoxy resin E51, 40g of propylene glycol methyl ether and 46g of nonionic epoxy active emulsifier b1 into a dispersion kettle, stir and mix to form a uniform and stable resin component; the temperature in the kettle is raised to 50°C, and 378g of deionized water is gradually dripped into the above resin component through a peristaltic pump. The dripping time lasts for 30min. After the water dripping is completed, the system is cooled to 35°C and discharged. The obtained epoxy resin aqueous dispersion is C1', with a solid content of 55wt% and an average particle size of the solid particles of 650nm.

[0121] Comparative Example C2':

[0122] Provided is an epoxy resin aqueous dispersion, comprising an anionic epoxy emulsifier a1' and a non-anionic epoxy emulsifier b1.

[0123] The preparation method thereof comprises the following steps:

[0124] Add 400g of epoxy resin E51, 40g of propylene glycol methyl ether, 25g of anionic epoxy emulsifier a1', and 46g of nonionic epoxy active emulsifier b1 into the dispersion kettle, stir and mix to form a uniform and stable resin component; the temperature in the kettle rises to 50°C, and 378g of deionized water is gradually dripped into the above resin component through a peristaltic pump, and the dripping time lasts for 30 minutes. After the water is dripped, the system is cooled to 35°C and the material is discharged. The obtained epoxy resin aqueous dispersion is C2', with a solid content of 55wt% and an average particle size of solid particles of 360nm.

[0125] Application Examples

[0126] The epoxy resin aqueous dispersions obtained in each embodiment and comparative example were mixed with water-based epoxy curing agent 8530 to prepare a series of paint films, wherein component A and component B were also required to prepare each paint film, and the formulas of component A and component B are shown in Tables 2 and 3 below;

[0127] The preparation of the paint film specifically includes the following steps:

[0128] 1) The epoxy resin aqueous dispersion obtained in each example and comparative example and the water-based epoxy curing agent 8530 were used to prepare a main paint (component A) and a curing agent (component B) according to the formulas in Table 2 and Table 3 respectively;

[0129] 2) The main paint (component A) obtained in Table 2 and the curing agent (component B) obtained in Table 3 were mixed in a mass ratio of 10:1, stirred for 15 minutes, and then the mixed material in step 1) and a small amount of deionized water were added to adjust the viscosity to the construction viscosity to prepare a mixed paint solution.

[0130] 3) Prepare the plates with the mixed paint liquids according to the industry operating standards (flash dry and leveling for 10 minutes, and bake at 80℃ for 30 minutes) to obtain the paint film. After the paint film is left to stand and cure for 7 days under the standard conditions of 23±2℃ and humidity 50±5%, various tests can be carried out according to the above test methods.

[0131] Among them, the resistance data is the test results after tracking for 20 days; the adhesion test results are graded from 0 to 5, with grade 0 being the best and grade 5 being the worst; the water resistance test results are graded from 0 to 5, with grade 5 being the best and grade 0 being the worst; the salt spray resistance test results are graded from 0 to 5, with grade 5 being the best and grade 0 being the worst. The performance test results are shown in Table 4 below:

[0132] Table 2: Formulation of component A

[0133]

[0134] Table 3: Formulation of component B

[0135]

[0136] Table 4 Test results of thermal stability of epoxy resin aqueous dispersion and paint film performance

[0137]

[0138] It can be seen from Table 4 that, compared with the comparative example, the epoxy resin aqueous dispersion of the embodiment has better thermal stability, and when used for the paint film, the durability is better.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An anionic epoxy emulsifier, characterized in that Contains at least one epoxy group derived from an epoxy resin and at least one sulfonate group derived from a carboxysulfonate.

2. The anionic epoxy emulsifier according to claim 1, characterized in that The molar ratio of the epoxy groups of the epoxy resin to the carboxyl groups in the carboxyl sulfonate is at least 2:1; preferably 2.5-4:

1.

3. The anionic epoxy emulsifier according to claim 1 or 2, characterized in that The epoxy resin contains at least two epoxy groups in its molecular structure. Preferably, the epoxy value of the epoxy resin is not greater than 0.6, more preferably not greater than 0.

55.

4. A method for preparing an anionic epoxy emulsifier according to any one of claims 1 to 3, characterized in that: The following steps are involved: A mixture containing epoxy resin, carboxyl sulfonate and a catalyst is subjected to a ring-opening reaction to obtain the anionic epoxy emulsifier.

5. The preparation method according to claim 4, characterized in that: The viscosity of the mixed material is 200-10000cp.

6. The preparation method according to claim 4 or 5, characterized in that: The reaction temperature of the ring-opening reaction is 100°C-150°C; preferably 120°C-140°C.

7. An epoxy resin aqueous dispersion, characterized in that: The invention comprises water and the anionic epoxy emulsifier described in any one of claims 1 to 3 or the anionic epoxy emulsifier prepared by the preparation method described in any one of claims 4 to 6.

8. The epoxy resin aqueous dispersion according to claim 7, characterized in that: Also includes at least one nonionic active emulsifier; Preferably, the molecular structure of the nonionic active emulsifier contains at least 10 ethoxy segments and at least 1 epoxy group; More preferably, in the nonionic active emulsifier, the content of ethoxy segments is 40wt%-95wt%, preferably 60wt%-85wt%.

9. The epoxy resin aqueous dispersion according to claim 8, characterized in that: The nonionic reactive emulsifier accounts for 3wt%-20wt% of the solid mass in the epoxy resin aqueous dispersion, preferably 8wt%-12wt%.

10. The epoxy resin aqueous dispersion according to claim 9, characterized in that: The total mass of the sulfonate groups of the anionic epoxy emulsifier accounts for 0.1 wt % to 1 wt % of the solid mass in the epoxy resin aqueous dispersion, and preferably 0.2 wt % to 0.5 wt %.

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