Polyacrylate dispersion, preparation method thereof and water-based paint

Abstract

The invention is applicable to the technical field of materials, and provides a polyacrylate dispersion, a preparation method and a water-based paint.The preparation method comprises the steps that a low-boiling-point solvent, an acrylate monomer and an initiator are added into high-pressure equipment for a reaction, and polyacrylate resin is obtained; under the condition of 50-75 DEG C, slowly pumping a neutralizer into the polyacrylate resin through a high-pressure pump to neutralize the polyacrylate resin for 30-50 minutes, and adding water to disperse the polyacrylate resin, so as to obtain the product. The neutralizer is obtained by compounding ammonia water and organic amine according to the mass ratio of 1: (0-6). Polyacrylate resin is preliminarily obtained through high-pressure equipment, a low-boiling-point solvent and an acrylate monomer, and the polyacrylate resin is neutralized through a composite neutralizer of ammonia water and organic amine to obtain the polyacrylate dispersion containing a large number of rigid rings and active hydroxyl groups. After being prepared into paint, the paint is matched with a water-based isocyanate curing agent, so that the paint has remarkable quick-drying performance and high-gloss and high-fullness characteristics, and the industrial production efficiency is greatly improved while the application scene of quick surface drying is met.

Description

Technical Field

[0001] The present application belongs to the field of material technology, and in particular relates to a polyacrylate dispersion and a preparation method thereof, and a water-based coating. Background Art

[0002] At present, water-based acrylic secondary dispersions are widely used in various industrial fields, including water-based wood coatings, engineering machinery equipment coatings, industrial equipment parts coatings, and vehicle shell coatings. Acrylic resins have high gloss, good fullness, good hardness, and excellent weather resistance. In particular, hydroxyl acrylate resins with functional groups can react with isocyanate curing agents to form water-based two-component polyurethane coatings, and their paint films have more excellent comprehensive properties. However, conventional acrylic dispersion resins are synthesized at normal pressure and high temperature, and require a large amount of high-boiling point co-solvents. Due to the slow evaporation of the solvent, the surface drying and actual drying speed of the paint film are slow, which seriously affects the efficiency of industrial construction; acrylic emulsions usually have a faster surface drying speed due to their large molecular weight and the absence of co-solvents, but they also have the disadvantages of poor fullness and low gloss of the paint film. Therefore, acrylic emulsions are usually used in the field of water-based wood paints that do not require high gloss and fullness, as well as some low-end water-based industrial paints.

[0003] However, in actual production, the market urgently needs a resin that meets the requirements of high gloss and fullness while also having fast surface drying and solid drying. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a method for preparing a polyacrylate dispersion, aiming to solve the technical problems of the existing water-based acrylic dispersions, such as slow surface drying, slow actual drying and low hardness.

[0005] The embodiment of the present application is implemented as follows: a method for preparing a polyacrylate dispersion comprises:

[0006] A low boiling point solvent, an acrylic acid ester monomer and an initiator are added into a high pressure device to carry out a polymerization reaction to obtain a polyacrylate resin;

[0007] At a temperature of 50-75° C., slowly pumping a neutralizing agent into the high-pressure device through a high-pressure pump to neutralize the polyacrylate resin for 30-50 minutes, adding water for dispersion to obtain a polyacrylate dispersion;

[0008] The neutralizing agent is prepared by mixing ammonia water and organic amine in a mass ratio of 1:(0-6); the mass fraction of the ammonia water is 25-28%.

[0009] Preferably, the acrylic acid ester monomers include the following monomers in percentage by mass:

[0010] 20-60% of monomer a1 with Tg>30°C and containing unsaturated double bonds, 10-40% of macrocyclic acrylic acid monomer a2, 0.5-5% of carboxyl-containing acrylic acid monomer a3 and 5-30% of hydroxyl-containing acrylic acid monomer a4.

[0011] Another object of an embodiment of the present application is a polyacrylate dispersion, which is prepared by the above-mentioned method for preparing a polyacrylate dispersion.

[0012] Another object of an embodiment of the present application is a water-based coating, which includes the above-mentioned polyacrylate dispersion.

[0013] The embodiment of the present application provides a method for preparing a polyacrylate dispersion, which uses high-pressure equipment, a low-boiling point, high-volatility solvent as a base, and after adding high-hardness acrylic ester monomers, a polyacrylate resin is initially obtained, and then neutralized with a composite neutralizer of ammonia water and organic amine to prepare an aqueous hydroxyl polyacrylic acid dispersion containing a large number of rigid rings and active hydroxyl groups. After being prepared into a paint, it is matched with a water-based isocyanate curing agent (or amino resin) to have significant quick-drying performance and high gloss and high fullness characteristics, which meets the application scenarios of fast surface drying while greatly improving the industrial production efficiency, and is particularly suitable for water-based inks, large workpiece construction in northern winter and other fields. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the present application more clear, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0015] The present application provides a method for preparing a polyacrylate dispersion, comprising:

[0016] A low boiling point solvent, an acrylic acid ester monomer and an initiator are added into a high pressure device to carry out a polymerization reaction to obtain a polyacrylate resin;

[0017] At a temperature of 50-75° C., the neutralizing agent is slowly pumped into the high-pressure equipment through a high-pressure pump to neutralize the polyacrylate resin for 30-50 minutes, and water is added for dispersion to obtain a polyacrylate dispersion.

[0018] The neutralizing agent is prepared by mixing ammonia water (25-28% mass fraction of commercially available ammonia water) and organic amine in a mass ratio of 1:(0-6); preferably, the neutralizing agent is prepared by mixing ammonia water and organic amine in a mass ratio of 1:(1-2).

[0019] Optionally, the neutralizing agent can be industrial ammonia (mass fraction 25-28%) or a mixture of ammonia and other organic amines. The organic amine used here can be N,N-dimethylethanolamine, triethanolamine, triethylamine, N-methyldiethanolamine, diethanolamine, diethylethanolamine, N,N-diethylhydroxylamine, etc.

[0020] It is worth noting that the polyacrylate resin dispersion is synthesized in a high-pressure device such as an autoclave, the entire monomer addition is done under the high-pressure device, and the neutralization reaction is also completed in the high-pressure device; the resin after neutralization is further dispersed by adding water in the high-pressure device. The part involving adding ammonia water must be pumped into the reactor by a high-pressure pump, and the autoclave must withstand a pressure of at least 3MPa.

[0021] Optionally, the neutralizing agent used can be added all at once or in batches; when added all at once, it needs to be added slowly by a high-pressure pump under high-pressure equipment; when added in batches, an organic amine such as N,N-dimethylethanolamine can be added first for pre-neutralization for a few minutes, and then industrial ammonia water can be slowly pumped into the reactor by a high-pressure pump; during the neutralizing agent addition process, the reaction temperature should be controlled at 50-75°C, preferably at 65°C; when adding N,N-dimethylethanolamine, it can be added at normal pressure or in a closed state, but the addition of ammonia water alone or the addition of ammonia water and N,N-dimethylethanolamine in combination must be slowly pumped into the autoclave by a high-pressure pump, and the autoclave needs to withstand a pressure of more than 1.5MPa, preferably more than 3MPa.

[0022] Wherein, the acrylic acid ester monomers include the following monomers in percentage by mass:

[0023] 20-60% of a hard acrylic monomer a1 having a high Tg (Tg>30°C) and containing an unsaturated double bond, 10-40% of a macrocyclic acrylic monomer a2, 0.5-5% of a carboxyl-containing acrylic monomer a3 and 5-30% of a hydroxyl-containing acrylic monomer a4.

[0024] Optionally, the hard acrylic monomer a1 can be methyl methacrylate, styrene, acrylonitrile, butyl methacrylate, tert-butyl methacrylate, etc.; the macrocyclic acrylic monomer a2 can be cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tetrahydrofuran (meth)acrylate, 2-phenoxyethyl (meth)acrylate, trimethylolpropane formal acrylate, etc.; the carboxyl-containing acrylic monomer a3 can be (meth)acrylic acid, itaconic acid, sulfonic styrene, etc., preferably acrylic acid; the hydroxyl-containing acrylic monomer a4 can be hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and its isomers, hydroxybutyl (meth)acrylate and its isomers, polyethylene glycol (meth)acrylate, etc., preferably hydroxyethyl methacrylate.

[0025] In addition, some functional monomers or additives can be used in the synthesis process of polyacrylate resin to adjust the molecular weight, including but not limited to cross-linking monomers, chain transfer agents, initiators, etc. The initiator can be one or more of benzoic acid peroxide, tert-butyl perbenzoate, di-tert-butyl peroxide, di-tert-amyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-amyl peroxy-2-ethylhexanoate, and di-tert-amyl peroxide.

[0026] The synthetic formula contains 4-12% (calculated by the mass of the water dispersion after dispersion, and the mass of the water dispersion is calculated unless otherwise specified) of a low boiling point solvent. The low boiling point solvent is a solvent with a boiling point lower than 130°C and / or a relative volatility greater than 0.2 and strong dissolving power.

[0027] Optionally, the low boiling point solvent can be one or more of ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, ethanol, n-propanol, isopropanol, butanol, isobutanol, cyclohexanone, propylene glycol, ethylene glycol methyl ether, and propylene glycol methyl ether, preferably low boiling point lipids, alcohols, and alcohol ethers, and more preferably ethyl acetate, butyl acetate, and isopropanol.

[0028] Alternatively, a typical synthesis process of polyacrylate dispersion can be as follows: 4-12% low boiling point organic solvent is used as the base in an autoclave, and nitrogen is passed to replace the air in the autoclave, and then the autoclave is sealed. Stirring is started, and after the reaction temperature is raised to 140-150°C, acrylic acid ester monomers are added dropwise in steps, the first part of the monomer is added dropwise for 3-5 hours, and the temperature is kept for 0.5-1 hour after the dropwise addition, and then the second part of the monomer is added dropwise for 2-2.5 hours, and a small amount of initiator is added after the second part of the monomer is added dropwise, and a small amount of initiator is continued to be added after the temperature is kept for 0.5-1 hour, and then the temperature is cooled to about 50-80°C, and a neutralizer is pumped in for neutralization, and then the neutralization and stirring are continued for half an hour and the temperature is cooled, and then hot water is slowly pumped in for dispersion, and then the temperature is cooled to about 30°C for discharge and washing the autoclave.

[0029] The embodiment of the present application also provides a polyacrylate dispersion, which is prepared by the above-mentioned method for preparing the polyacrylate dispersion.

[0030] Furthermore, the present application also provides a water-based coating, which includes the above-mentioned polyacrylate dispersion. For example, a wetting agent, a defoaming agent, a leveling agent, a pH regulator, a thickener, a color paste, etc. are added to the above-mentioned polyacrylate dispersion to prepare a water-based coating. Although the specific embodiment only describes one of the coating formulas, those skilled in the art can select the type of solvent in the formula according to actual needs, and the scope of the present application should not be limited by this.

[0031] The polyacrylate dispersion and its preparation method are described in detail with specific examples as follows. The experimental methods used in the following examples are conventional methods unless otherwise specified; the materials and reagents used are all commercially available unless otherwise specified.

[0032] Comparative Example 1: Preparation of polyacrylate dispersion

[0033] Add 45g of No. 100 solvent oil, 45g of propylene glycol butyl ether, and 2g of di-tert-amyl peroxide into a reaction bottle, stir and heat to 140-146°C, while introducing nitrogen to exhaust the air in the bottle, maintain the temperature within this range, and prepare to dropwise add acrylate monomers and initiators;

[0034] 50g of methyl methacrylate, 55g of styrene, 90g of n-butyl methacrylate, 104g of hydroxyethyl methacrylate, 66g of cyclohexyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed evenly and poured into a dropping funnel. The mixture was dripped after 4-5h and kept warm for half an hour. Then 30g of n-butyl methacrylate, 14g of acrylic acid, 30g of hydroxyethyl methacrylate, 16g of cyclohexyl methacrylate, 2g of di-tert-butyl peroxide and 0.25g of n-dodecyl mercaptan were mixed evenly, loaded into a dropping funnel and evenly dripped. The mixture was added after 2-2.5h. Then 1g of tert-amyl peroxide was added to the reactant, and the mixture was kept warm for 1h. Then 2g of tert-amyl peroxide was added and kept warm for 1.5h. The mixture was cooled to 65°C, DMEA was added and stirred for 30 minutes, and water was added to disperse the mixture. A total of 490g of water was added. Continue stirring and cooling for 1 hour. When the emulsion temperature reaches below 40°C, the target dispersion can be obtained by discharging the material.

[0035] Comparative Example 2: Preparation of polyacrylate dispersion

[0036] Add 45g of No. 100 solvent oil, 45g of propylene glycol butyl ether, and 2g of di-tert-amyl peroxide into the autoclave and start stirring. At the same time, introduce nitrogen to exhaust the air in the autoclave. Raise the temperature to 140-146°C and react at normal pressure. Prepare to add acrylic acid ester monomers and initiators dropwise.

[0037] 50g of methyl methacrylate, 55g of styrene, 90g of n-butyl methacrylate, 104g of hydroxyethyl methacrylate, 66g of cyclohexyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed and poured into a monomer tank, dripped through a high-pressure pump for 4-5h, and kept warm for half an hour; 30g of n-butyl methacrylate, 14g of acrylic acid, 30g of hydroxyethyl methacrylate, 16g of cyclohexyl methacrylate, 2g of di-tert-butyl peroxide and 0.25g of n-dodecyl mercaptan were mixed and poured into a monomer tank, dripped through a high-pressure pump for 2-2.5h, and then 1g of tert-amyl peroxide was added to the reactant, kept warm for 1h, and then 2g of tert-amyl peroxide was added and kept warm for 1.5h; then the temperature was lowered to 65°C, all valves of the autoclave except the feed port were closed to hold the pressure, and 5g of tert-amyl peroxide was slowly pumped into the reactant with a high-pressure pump. After adding the neutralizer, stir for 40 minutes while cooling down. Then pump in hot water for dispersion, adding 490g of water in total. Continue stirring and cooling down for 1h. When the emulsion temperature reaches below 40℃, the target dispersion can be obtained.

[0038] Comparative Example 3: Preparation of polyacrylate dispersion

[0039] Add 45g of No. 100 solvent oil, 45g of propylene glycol butyl ether, and 2g of di-tert-amyl peroxide into the autoclave and start stirring. At the same time, introduce nitrogen to exhaust the air in the autoclave. Raise the temperature to 140-146°C and react at normal pressure. Prepare to add acrylic acid ester monomers and initiators dropwise.

[0040] 50g of methyl methacrylate, 55g of styrene, 156g of n-butyl methacrylate, 104g of hydroxyethyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed and poured into a monomer tank, dripped through a high-pressure pump for 4-5h, and kept warm for half an hour; then 46g of n-butyl methacrylate, 14g of acrylic acid, 30g of hydroxyethyl methacrylate, 2g of di-tert-butyl peroxide and 0.25g of n-dodecyl mercaptan were mixed and poured into a monomer tank, dripped evenly through a high-pressure pump for 2-2.5h, then 1g of tert-amyl peroxide was added to the reactant, kept warm for 1h, and then 2g of tert-amyl peroxide was added and kept warm for 1.5h, then the temperature was lowered to 65°C, all valves of the autoclave except the feed port were closed to hold the pressure, and 5g of tert-amyl peroxide was slowly pumped into the reactant with a high-pressure pump. After adding the neutralizer, stir for 40 minutes while cooling down. Then pump in hot water for dispersion, adding 490g of water in total. Continue stirring and cooling down for 1h. When the emulsion temperature reaches below 40℃, the target dispersion can be obtained.

[0041] Comparative Example 4: Preparation of polyacrylate dispersion

[0042] Add 45g of butyl acetate, 45g of isopropanol, and 2g of di-tert-amyl peroxide into the autoclave and start stirring. At the same time, introduce nitrogen to exhaust the air in the bottle, seal the autoclave and hold the pressure. Raise the temperature to 140-146°C, maintain this temperature range, and prepare to dropwise add the acrylic ester monomer and initiator.

[0043] 50g of methyl methacrylate, 55g of styrene, 90g of n-butyl methacrylate, 104g of hydroxyethyl methacrylate, 66g of cyclohexyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed evenly and poured into a monomer tank, and dripped through a high-pressure pump for 4-5h, and kept warm for half an hour; then 30g of n-butyl methacrylate, 14g of acrylic acid, 30g of hydroxyethyl methacrylate, 16g of cyclohexyl methacrylate, 2g of di-tert-butyl peroxide and 0.25g of n-dodecyl mercaptan were mixed evenly and dripped evenly through a high-pressure pump for 2-2.5h, and then 1g of tert-amyl peroxide was added to the reactant, and kept warm for 1h, and then 2g of tert-amyl peroxide was added and kept warm for 1.5h, and the temperature was lowered to 95°C, and 5g of tert-amyl peroxide was slowly pumped into the reactant with a high-pressure pump. A mixture of DMEA and 3.1g industrial ammonia water. The pressure in the kettle increases rapidly when the composite neutralizer is added. For safety reasons, the neutralizer addition time is extended to 15 minutes. After that, the kettle is stirred for 30 minutes while cooling down. When the pressure in the kettle no longer changes, hot water is pumped in for dispersion. A total of 490g of water is added. Stirring and cooling down for 1h. When the emulsion temperature reaches below 40°C, the target dispersion resin can be discharged. In view of the fact that the pressure increases sharply when the composite neutralizer is added at high temperature, it is not recommended to add amine at this high temperature for safety reasons.

[0044] Example 1: Preparation of polyacrylate dispersion

[0045] Add 45g of butyl acetate, 45g of isopropanol, and 2g of di-tert-amyl peroxide into the autoclave and start stirring. At the same time, introduce nitrogen to exhaust the air in the bottle, seal the autoclave and hold the pressure. Raise the temperature to 140-146°C, maintain this temperature range, and prepare to dropwise add the acrylic ester monomer and initiator.

[0046] 50g of methyl methacrylate, 55g of styrene, 90g of n-butyl methacrylate, 104g of hydroxyethyl methacrylate, 66g of cyclohexyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed evenly and poured into a monomer tank, and dripped through a high-pressure pump for 4-5h, and kept warm for half an hour; then 30g of n-butyl methacrylate, 14g of acrylic acid, 30g of hydroxyethyl methacrylate, 16g of cyclohexyl methacrylate, 2g of di-tert-butyl peroxide and 0.25g of n-dodecyl mercaptan were mixed evenly and dripped evenly with a high-pressure pump for 2-2.5h, and then 1g of tert-amyl peroxide was added to the reactant, and kept warm for 1h, and then 2g of tert-amyl peroxide was added and kept warm for 1.5h, and the temperature was lowered to 65°C, and 5g of tert-amyl peroxide was slowly pumped into the reactant with a high-pressure pump. After adding the neutralizer, stir for 40 minutes while cooling down. When the pressure in the kettle no longer changes, pump in hot water for dispersion, adding a total of 490g of water. Continue stirring and cooling for 1 hour. When the emulsion temperature reaches below 40°C, the target dispersion can be obtained.

[0047] Example 2: Preparation of polyacrylate dispersion

[0048] Add 45g of butyl acetate, 45g of isopropanol, and 2g of di-tert-amyl peroxide into the autoclave and start stirring. At the same time, introduce nitrogen to exhaust the air in the bottle, seal the autoclave and hold the pressure. Raise the temperature to 140-146°C, maintain this temperature range, and prepare to dropwise add the acrylic ester monomer and initiator.

[0049] 50g of methyl methacrylate, 55g of styrene, 156g of n-butyl methacrylate, 104g of hydroxyethyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed and poured into a monomer tank, and dripped through a high-pressure pump for 4-5h, and kept warm for half an hour; then 46g of n-butyl methacrylate, 14g of acrylic acid, 30g of hydroxyethyl methacrylate, 2g of di-tert-butyl peroxide and 0.25g of n-dodecyl mercaptan were mixed and dripped evenly through a high-pressure pump for 2-2.5h, and then 1g of tert-amyl peroxide was added to the reactant, and kept warm for 1h, and then 2g of tert-amyl peroxide was added and kept warm for 1.5h, and the temperature was lowered to 65°C, and a mixture of 5g of DMEA and 3.1g of industrial ammonia water was slowly pumped into the reactant with a high-pressure pump, and the neutralizer was added and stirred for 40 minutes while cooling; when the pressure in the kettle no longer changed, hot water was pumped in for dispersion, and a total of 490g of water was added. Continue stirring and cooling for 1 hour. When the emulsion temperature reaches below 40°C, the target dispersion resin can be obtained by discharging the emulsion.

[0050] Example 3: Preparation of polyacrylate dispersion

[0051] Add 45g of butyl acetate, 45g of isopropanol, and 2g of di-tert-amyl peroxide into the autoclave and start stirring. At the same time, introduce nitrogen to exhaust the air in the bottle, seal the autoclave and hold the pressure. Raise the temperature to 140-146°C, maintain this temperature range, and prepare to dropwise add the acrylic ester monomer and initiator.

[0052] 50g of methyl methacrylate, 55g of styrene, 90g of n-butyl methacrylate, 104g of hydroxyethyl methacrylate, 66g of cyclohexyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed evenly and poured into a monomer tank. The mixture was dripped through a high-pressure pump for 4-5h and kept warm for half an hour. Then 30g of n-butyl methacrylate, 14g of acrylic acid, 30g of hydroxyethyl methacrylate, 16g of cyclohexyl methacrylate, 2g of di-tert-butyl peroxide and 0.25g of n-dodecyl mercaptan were mixed evenly and dripped evenly through a high-pressure pump for 2-2.5h. Then 1g of tert-amyl peroxide was added to the reactant and kept warm for 1h. Then 2g of tert-amyl peroxide was added and kept warm for 1.5h. The temperature was lowered to 65°C and 18g of tert-amyl peroxide was slowly pumped into the reactant through a high-pressure pump. After adding DMEA and neutralizer, stir for 40 minutes while cooling down. When the pressure in the kettle no longer changes, pump in hot water for dispersion, and add 490g of water in total. Continue stirring and cooling for 1h. When the emulsion temperature reaches below 40℃, the target dispersion can be obtained.

[0053] Example 4: Preparation of polyacrylate dispersion

[0054] Add 45g of butyl acetate, 45g of isopropanol, and 2g of di-tert-amyl peroxide into the autoclave and start stirring. At the same time, introduce nitrogen to exhaust the air in the bottle, seal the autoclave and hold the pressure. Raise the temperature to 140-146°C, maintain this temperature range, and prepare to dropwise add the acrylic ester monomer and initiator.

[0055] 50g of methyl methacrylate, 55g of styrene, 90g of n-butyl methacrylate, 104g of hydroxyethyl methacrylate, 66g of cyclohexyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed evenly and poured into a monomer tank, and dripped through a high-pressure pump for 4-5h, and kept warm for half an hour; then 30g of n-butyl methacrylate, 14g of acrylic acid, 30g of hydroxyethyl methacrylate, 16g of cyclohexyl methacrylate, 2g of di-tert-butyl peroxide and 0.25g of n-dodecyl mercaptan were mixed evenly and dripped evenly with a high-pressure pump for 2-2.5h, and then 1g of tert-amyl peroxide was added to the reactant, and kept warm for 1h, and then 2g of tert-amyl peroxide was added and kept warm for 1.5h, and the temperature was lowered to 65°C, the valve was opened to make the reactor at normal pressure, and 5g of tert-amyl peroxide was slowly pumped into the reactant with a pump. Mixture of DMEA and 3g saturated ammonia water, stir for 30 minutes while cooling after adding neutralizer; pump in water for dispersion, add 490g of water in total. Continue stirring and cooling for 1h, and when the emulsion temperature reaches below 40℃, discharge the material to obtain the target dispersion.

[0056] Example 5: Preparation of polyacrylate dispersion

[0057] Add 45g of butyl acetate, 45g of isopropanol, and 2g of di-tert-amyl peroxide into the autoclave and start stirring. At the same time, introduce nitrogen to exhaust the air in the bottle, seal the autoclave and hold the pressure. Raise the temperature to 140-146°C, maintain this temperature range, and prepare to dropwise add the acrylic ester monomer and initiator.

[0058] 50g of methyl methacrylate, 55g of styrene, 90g of n-butyl methacrylate, 104g of hydroxyethyl methacrylate, 66g of cyclohexyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed evenly and poured into a monomer tank. The mixture was dripped through a high-pressure pump for 4-5h and kept warm for half an hour. Then 30g of n-butyl methacrylate, 14g of acrylic acid, 30g of hydroxyethyl methacrylate, 16g of cyclohexyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were added. 2g of butyl peroxide and 0.25g of n-dodecyl mercaptan are mixed evenly and added evenly with a high-pressure pump. It takes 2-2.5 hours to add. Then, 1g of tert-amyl peroxide is added to the reactant, and the temperature is kept for 1 hour. Then, 2g of tert-amyl peroxide is added and the temperature is kept for 1.5 hours. The temperature is lowered to 65°C. 10.5g of ammonia water is slowly pumped into the reactant with a high-pressure pump. After the neutralizer is added, the temperature is lowered and stirred for 40 minutes. When the pressure in the kettle no longer changes, hot water is pumped in for dispersion, and a total of 480g of water is added. Stirring and cooling are continued for 1 hour. When the emulsion temperature reaches below 40°C, the target dispersion resin can be obtained.

[0059] Example 6: Preparation of polyacrylate dispersion

[0060] Add 45g of butyl acetate, 45g of isopropanol, and 2g of di-tert-amyl peroxide into the autoclave and start stirring. At the same time, introduce nitrogen to exhaust the air in the bottle, seal the autoclave and hold the pressure. Raise the temperature to 140-146°C, maintain this temperature range, and prepare to dropwise add the acrylic ester monomer and initiator.

[0061] 50g of methyl methacrylate, 55g of styrene, 90g of n-butyl methacrylate, 104g of hydroxyethyl methacrylate, 66g of cyclohexyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed evenly and poured into a monomer tank, and dripped through a high-pressure pump for 4-5h, and kept warm for half an hour; then 30g of n-butyl methacrylate, 14g of acrylic acid, 30g of hydroxyethyl methacrylate, 16g of cyclohexyl methacrylate, 2g of di-tert-butyl peroxide and 0.25g of n-dodecyl mercaptan were mixed evenly and dripped evenly through a high-pressure pump for 2-2.5h, and then 1g of tert-amyl peroxide was added to the reactant, and kept warm for 1h, and then 2g of tert-amyl peroxide was added and kept warm for 1.5h, and the temperature was lowered to 65°C, and 2g of tert-amyl peroxide was slowly pumped into the reactant with a high-pressure pump. After adding the neutralizer, stir for 40 minutes while cooling down. When the pressure in the kettle no longer changes, pump in hot water for dispersion, and add a total of 490g of water. Continue stirring and cooling for 1 hour. When the emulsion temperature reaches below 40°C, the target dispersion resin can be obtained.

[0062] Example 7: Preparation of polyacrylate dispersion

[0063] Add 45g of butyl acetate, 45g of isopropanol, and 2g of di-tert-amyl peroxide into the autoclave and start stirring. At the same time, introduce nitrogen to exhaust the air in the bottle, seal the autoclave and hold the pressure. Raise the temperature to 140-146°C, maintain this temperature range, and prepare to dropwise add the acrylic ester monomer and initiator.

[0064] 50g of methyl methacrylate, 55g of styrene, 90g of n-butyl methacrylate, 104g of hydroxyethyl methacrylate, 66g of cyclohexyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed evenly and poured into a monomer tank. The mixture was dripped through a high-pressure pump for 4-5h and kept warm for half an hour. Then 14g of acrylic acid, 30g of hydroxyethyl methacrylate, 16g of cyclohexyl methacrylate, 2g of di-tert-butyl peroxide, 0.25g of dodecanethiol was mixed evenly and added evenly with a high-pressure pump. It took 2-2.5 hours to add. Then, 1g of tert-amyl peroxide was added to the reactant, and the mixture was kept warm for 1 hour. Then, 2g of tert-amyl peroxide was added and the mixture was kept warm for 1.5 hours. The temperature was lowered to 65°C. A complex of 5g of triethanolamine and 5g of ammonia water was slowly pumped into the reactant with a high-pressure pump. After the neutralizer was added, the mixture was stirred for 40 minutes while the temperature was lowered. When the pressure in the kettle no longer changed, hot water was pumped in for dispersion, and a total of 490g of water was added. Stirring and cooling continued for 1 hour. When the emulsion temperature reached below 40°C, the target dispersion resin was obtained.

[0065] Example 8: Preparation of polyacrylate dispersion

[0066] Add 45g of butyl acetate, 45g of propylene glycol methyl ether, and 2g of di-tert-amyl peroxide into the autoclave and start stirring, while introducing nitrogen to exhaust the air in the bottle, and seal the autoclave to hold the pressure. Raise the temperature to 140-146°C, maintain this temperature range, and prepare to dropwise add the acrylic ester monomer and initiator.

[0067] 50g of methyl methacrylate, 55g of styrene, 90g of n-butyl methacrylate, 104g of hydroxyethyl methacrylate, 66g of cyclohexyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed evenly and poured into a monomer tank, and dripped through a high-pressure pump for 4-5h, and kept warm for half an hour; 14g of acrylic acid, 30g of hydroxyethyl methacrylate, 16g of cyclohexyl methacrylate, 2g of di-tert-butyl peroxide and 0.25g of n-dodecyl mercaptan were mixed evenly and dripped evenly through a high-pressure pump for 2-2.5h, and then 1g of tert-amyl peroxide was added to the reactant, and kept warm for 1h, and then 2g of tert-amyl peroxide was added and kept warm for 1.5h, and the temperature was lowered to 65°C, and 5g of tert-amyl peroxide was slowly pumped into the reactant with a high-pressure pump. The mixture of DMEA and 3.1g ammonia water is stirred for 40 minutes while cooling after adding the neutralizer; when the pressure in the kettle no longer changes, hot water is pumped in for dispersion, and a total of 490g of water is added. Stirring and cooling are continued for 1h, and when the emulsion temperature reaches below 40°C, the target dispersion can be obtained.

[0068] Example 9: Preparation of polyacrylate dispersion

[0069] Add 45g of butyl acetate, 45g of isopropanol, and 2g of di-tert-amyl peroxide into the autoclave and start stirring. At the same time, introduce nitrogen to exhaust the air in the bottle, seal the autoclave and hold the pressure. Raise the temperature to 140-146°C, maintain this temperature range, and prepare to dropwise add the acrylic ester monomer and initiator.

[0070] 68g of methyl methacrylate, 61g of styrene, 132g of isobornyl methacrylate, 104g of hydroxyethyl methacrylate, 66g of cyclohexyl methacrylate, 7.3g of di-tert-butyl peroxide and 1g of n-dodecyl mercaptan were mixed evenly and poured into a monomer tank. The mixture was dripped through a high-pressure pump for 4-5h and kept warm for half an hour. Then 10g of acrylic acid, 30g of hydroxyethyl methacrylate, 34g of n-butyl methacrylate, 16g of isobornyl methacrylate and di-tert-butyl peroxide were added. 2g of peroxide and 0.25g of n-dodecyl mercaptan are mixed evenly and added evenly with a high-pressure pump. It takes 2-2.5 hours to add. Then, 1g of tert-amyl peroxide is added to the reactant, and the temperature is kept for 1 hour. Then, 2g of tert-amyl peroxide is added and the temperature is kept for 1.5 hours. The temperature is lowered to 60°C. A complex of 4g of DMEA and 4g of ammonia water is slowly pumped into the reactant with a high-pressure pump. After the neutralizer is added, the temperature is lowered while stirring for 40 minutes. When the pressure in the kettle no longer changes, hot water is pumped in for dispersion, and a total of 490g of water is added. Stirring and cooling are continued for 1 hour. When the emulsion temperature reaches below 40°C, the target dispersion can be obtained.

[0071] Example 10: Preparation of polyacrylate dispersion

[0072] Add 45g of butyl acetate, 45g of propylene glycol methyl ether, and 2g of di-tert-amyl peroxide into the autoclave and start stirring, while introducing nitrogen to exhaust the air in the bottle, and seal the autoclave to hold the pressure. Raise the temperature to 140-146°C, maintain this temperature range, and prepare to dropwise add the acrylic ester monomer and initiator.

[0073] 34 g of methyl methacrylate, 65 g of styrene, 94 g of hydroxyethyl methacrylate, 100 g of isobornyl methacrylate, 72 g of tert-butyl methacrylate, 7.3 g of di-tert-butyl peroxide, and 1 g of n-dodecyl mercaptan were mixed evenly and poured into a monomer tank. The mixture was dripped through a high-pressure pump for 4-5 hours and kept warm for half an hour. Then 18 g of acrylic acid, 20 g of hydroxyethyl methacrylate, 25 g of isobornyl methacrylate, 27 g of tert-butyl methacrylate, and 1 g of di-tert-butyl peroxide were added. 2g of DMEA and 0.25g of n-dodecyl mercaptan are mixed evenly and added evenly with a high-pressure pump. It takes 2-2.5 hours to add. Then, 1g of tert-amyl peroxide is added to the reactant, and the temperature is kept for 1 hour. Then, 2g of tert-amyl peroxide is added and the temperature is kept for 1.5 hours. The temperature is lowered to 55°C. A complex of 1.5g of DMEA and 9g of ammonia water is slowly pumped into the reactant with a high-pressure pump. After the neutralizer is added, the temperature is lowered while stirring for 40 minutes. When the pressure in the kettle no longer changes, hot water is pumped in for dispersion, and a total of 490g of water is added. Stirring and cooling are continued for 1 hour. When the emulsion temperature reaches below 40°C, the target dispersion can be obtained.

[0074] The polyacrylic acid dispersions prepared in the above Examples 1-10 and Comparative Examples 1-4 were used for paint preparation. The specific formula was as follows: by mass percentage, 63% polyacrylate dispersion, 0.3% wetting defoamer AD-01, 2.5% diethylene glycol butyl ether DBG, 2.1% dipropylene glycol butyl ether DPNB, 1.6% deionized water, 0.5% wetting agent Tego-4100, 0.4% flash rust inhibitor FA-179, 29.4% titanium dioxide slurry with a mass fraction of 75%, and 0.2% thickener XS-71; wherein, the formulation of titanium dioxide slurry with a mass fraction of 75% was as follows: by mass percentage, 16.8% deionized water, 3% propylene glycol PG, 0.02% defoamer BYK024, 5% dispersant BYK190, 75% titanium dioxide R706, and 0.2% rheological additive WT-105A. In addition, Bayer XP2655 curing agent was diluted with PMA to 80% as curing agent component; the paint was prepared with a molar ratio of NCO:OH=1.6, and sprayed on tinplate, and the surface drying speed was observed in a room at 25°C and 32% humidity, and the pendulum hardness and gloss of the paint film were measured one, three, and seven days after the spraying. The test results are shown in Table 1 below.

[0075] Among them, the surface drying speed is measured by the cotton ball blowing method. Place a cotton ball on the coating film at intervals, and blow gently in the horizontal direction with your mouth 10-15cm away from the cotton ball. If it can be blown away and no cotton fibers are left on the film surface, the surface is considered to be dry. The actual drying speed is measured by the cotton ball pressing method: place a cotton ball on the surface of the water-based paint film, and then press a 200g weight on it. After 30 seconds, remove the weight and turn the sample plate over. If the cotton ball can fall freely and the fibers do not stick to the paint film, even if there are a few fibers, they can be gently flicked off, then the water-based paint film is considered to be dry. The self-drying hardness is measured by a pendulum hardness tester at a temperature of 28.5℃ and a humidity of 41%. The gloss is tested by a BYK gloss meter at an angle of 60 degrees.

[0076] Table 1

[0077]

[0078] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

[0079] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a polyacrylate dispersion, characterized in that: include: Adding a low boiling point solvent, an acrylic acid ester monomer and an initiator into a high pressure device to carry out a polymerization reaction to obtain a polyacrylate resin; At a temperature of 50-75° C., slowly pumping a neutralizing agent into the high-pressure device through a high-pressure pump to neutralize the polyacrylate resin for 30-50 minutes, adding water for dispersion to obtain a polyacrylate dispersion; The neutralizing agent is prepared by mixing ammonia water and organic amine in a mass ratio of 1:(0-6); the mass fraction of the ammonia water is 25-28%.

2. The method for preparing a polyacrylate dispersion according to claim 1, characterized in that: The neutralizing agent is prepared by compounding ammonia water and organic amine in a mass ratio of 1:(1-2).

3. The method for preparing a polyacrylate dispersion according to claim 1, characterized in that: The acrylic acid ester monomers include the following monomers in percentage by weight: 20-60% of monomer a1 with Tg>30°C and containing unsaturated double bonds, 10-40% of macrocyclic acrylic acid monomer a2, 0.5-5% of carboxyl-containing acrylic acid monomer a3 and 5-30% of hydroxyl-containing acrylic acid monomer a4.

4. The method for preparing a polyacrylate dispersion according to claim 3, characterized in that: The hard acrylic monomer a1 is one or more of methyl methacrylate, styrene, acrylonitrile, butyl methacrylate and tert-butyl methacrylate; The macrocyclic acrylic acid monomer a2 is one or more of cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, tetrahydrofuranyl acrylate, tetrahydrofuranyl methacrylate, 2-phenoxyethyl acrylate, 2-phenoxymethyl acrylate, and trimethylolpropane formal acrylate; The acrylic acid monomer a3 is one or more of acrylic acid, methacrylic acid, itaconic acid, and sulfonyl styrene; The acrylic monomer a4 is one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and its isomers, hydroxypropyl methacrylate and its isomers, hydroxybutyl acrylate and its isomers, hydroxybutyl methacrylate and its isomers, and polyethylene glycol methacrylate.

5. The method for preparing a polyacrylate dispersion according to claim 1, characterized in that: The low boiling point solvent is a solvent having a boiling point lower than 130° C. and / or a relative volatility greater than 0.

2.

6. The method for preparing a polyacrylate dispersion according to claim 1 or 5, characterized in that: The low boiling point solvent is one or more of ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, ethanol, n-propanol, isopropanol, butanol, isobutanol, cyclohexanone, propylene glycol, ethylene glycol methyl ether, and propylene glycol methyl ether; The initiator is one or more of benzoic acid peroxide, tert-butyl perbenzoate, di-tert-butyl peroxide, di-tert-amyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-amyl peroxy-2-ethylhexanoate, and di-tert-amyl peroxide.

7. The method for preparing a polyacrylate dispersion according to claim 1 or 2, characterized in that: The organic amine is one or more of N,N-dimethylethanolamine, triethanolamine, triethylamine, N-methyldiethanolamine, diethanolamine, diethylethanolamine, and N,N-diethylhydroxylamine.

8. The method for preparing a polyacrylate dispersion according to claim 1, characterized in that: The high-pressure equipment has a pressure resistance of at least 3 MPa.

9. A polyacrylate dispersion, characterized in that: The polyacrylate dispersion is prepared by the preparation method of the polyacrylate dispersion according to any one of claims 1 to 8.

10. A water-based paint, characterized in that: The water-based coating comprises the polyacrylate dispersion according to claim 9.

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