Environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion and preparation method thereof

Abstract

The present invention proposes an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic emulsion and a preparation method, which belongs to the technical field of polymer material synthesis, and is used to solve the technical problems of low hardness and poor hiding power of water-based acrylic resin emulsion after film formation. The present invention includes the following raw materials by weight: 40-54.5 parts of soft monomers, 64-77 parts of hard monomers, 5-6 parts of acrylic epoxy monomers, 26-29.5 parts of acrylic carboxyl monomers, 1.5-2 parts of acetoacetoxyethyl methacrylate, 1-2 parts of proteins, 1.2-1.8 parts of initiators, 0.1-0.3 parts of catalysts, 1.4-2 parts of emulsifiers, 0.5-1 parts of pH buffers, 130-160 parts of deionized water, and 5-6.5 parts of neutralizers. The preparation process of the present invention is relatively simple, and the prepared acrylic resin emulsion has high solid and low viscosity, uniform particle size distribution, and the coating prepared therefrom has strong hiding power and high gloss.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material synthesis, and in particular relates to an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion and a preparation method thereof. Background Art

[0002] Traditional solvent-based coatings are volatile organic solvents and generally produce a large amount of odorous and toxic gases, which cause pollution and harm to the environment and human body. Therefore, governments, coatings industry and related industries have formulated VOCs emission regulations, which has also greatly accelerated the development of water-based coating products, especially environmentally friendly coating products. The main film-forming substances in coatings are alkyd resins, polyurethane resins and acrylic resins. Currently, acrylic emulsion resins are used in large quantities. Acrylic resins are mainly copolymerized with vinyl (meth) acrylic monomers. They have excellent weather resistance and aging resistance, and are highly designable. They are widely used in many fields.

[0003] However, the acrylic emulsions currently on the market still have the defects of insufficient solid content and viscosity, hot stickiness and cold brittleness, poor water resistance and hiding power after emulsion film formation, weak mechanical properties (hardness, adhesion) and so on, which are difficult to meet the application of special industries, especially in the high-end construction industry. In order to overcome the above shortcomings, domestic and foreign researchers usually use methods such as grafting, blending, copolymerization and cross-linking for modification. Patent Publication No. CN102649835A discloses a hybrid silicon acrylic ester emulsion and a preparation method thereof. The emulsion has a good appearance, but the water resistance of the resin coating is relatively poor, and severe water whitening and blistering occur after soaking in water for one day. Patent Publication No. CN109651550A discloses a fatty acid-modified acrylic emulsion and a preparation method thereof. The drying speed of the emulsion coating is relatively fast, but the emulsion solid content is low, and the gloss, hardness and other properties of the coating are also relatively poor. Therefore, among the above modification methods, although there are significant improvements in the use of functional monomer copolymerization or grafting to modify acrylic emulsion resin, toxic gases will be generated during the modification process or when the resin is used, which will endanger human health to a certain extent. In addition, the modified resin still has the problem of poor hiding power and is difficult to meet the needs of the high-end construction industry. Summary of the invention

[0004] In view of the technical problems of low hardness and poor hiding power of water-based acrylic resin emulsion after film formation, the present invention proposes an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion and a preparation method. The resin emulsion has good appearance, high solid content and low viscosity, uniform particle size distribution, smooth and refreshing surface after varnish film formation, glossiness of more than 100%, and the hardness and adhesion of the coating film reach 2H and 0 levels respectively.

[0005] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A method for preparing an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion, the steps of which are as follows:

[0007] (1) Deionized water, emulsifier and pH buffer were added to a 500 mL four-necked flask in sequence, heated to 40-55° C. in a water bath, and continuously stirred mechanically at a speed of 150-200 r / min;

[0008] (2) 0.69-0.75 times of soft monomer, 0.15-0.17 times of hard monomer and acrylic epoxy monomer are added to a 150 mL flask, and mixed evenly to obtain a core resin pre-emulsion A; a catalyst, 0.15-0.16 times of soft monomer, 0.44-0.47 times of hard monomer, 0.94-0.97 times of acrylic carboxyl monomer and ethyl acetoacetate methacrylate are added to a 150 mL flask, and mixed evenly to obtain a base resin pre-emulsion B; 0.10-0.15 times of soft monomer, 0.37-0.39 times of hard monomer, 0.03-0.05 times of acrylic carboxyl monomer, 0.25 times of initiator and protein are added to a 150 mL flask, and mixed evenly to obtain a shell resin pre-emulsion C;

[0009] (3) 1 / 7-1 / 5 of the mixed solution of pre-emulsion A is uniformly added to a 500 mL four-necked flask, and after uniform stirring for 3-8 minutes, 1 / 40-3 / 40 of the initiator is added, and after keeping the temperature for 15-25 minutes, 1 / 5-2 / 5 of the initiator is added, and then the remaining mixed solution of pre-emulsion A is uniformly added dropwise for 45-50 minutes, and then the temperature is kept for 20-40 minutes;

[0010] (4) After the insulation is completed, 1 / 7-1 / 5 of the mixed solution of pre-emulsion B is added, and after stirring at a uniform speed for 3-8 minutes, 3 / 40-5 / 40 of the initiator is added. After the insulation reaction is carried out for 20-30 minutes, 1 / 5-2 / 5 of the initiator is added, and then the remaining mixed solution of pre-emulsion B is added dropwise at a very slow rate, and the addition time is maintained at 100-120 minutes. After the addition is completed, the insulation reaction is carried out for 20-40 minutes;

[0011] (5) Finally, slowly add the mixed solution of pre-emulsion C dropwise for 65-75 min, and keep the temperature for reaction for 1.5-2.5 h after the addition is completed;

[0012] (6) When the temperature reaches 40° C., a neutralizing agent is added and stirred evenly, and the pH is adjusted to 8.5-9 to obtain an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion.

[0013] Preferably, the step (3) is as follows: 1 / 6 of the mixed solution of pre-emulsion A is uniformly added to a 500 mL four-necked flask, 1 / 20 of the initiator is added after uniform stirring for 5 minutes, 3 / 10 of the initiator is added after heat preservation for 20 minutes, and then the remaining mixed solution of pre-emulsion A is dripped at a uniform speed, the dripping is completed for 45-50 minutes, and the heat preservation is continued for 30 minutes.

[0014] Preferably, in step (4), after the insulation is completed, 1 / 6 of the mixed solution of pre-emulsion B is added, and after uniform stirring for 5 minutes, 2 / 20 of the initiator is added, and after the insulation reaction is carried out for 25 minutes, 3 / 10 of the initiator is added, and then the remaining mixed solution of pre-emulsion B is added dropwise at a very slow rate, and the dropping time is maintained at 100-120 minutes. After the addition is completed, the insulation reaction is carried out for 30 minutes.

[0015] The mass ratio of the soft monomer to the hard monomer in the core resin pre-emulsion is (2.8-3.0):1, wherein the hard monomer is methyl methacrylate; the mass ratio of the acrylic epoxy monomer in the core resin pre-emulsion to the acrylic carboxyl monomer in the base resin pre-emulsion is 1:(4.5-5);

[0016] The protein is any one of soy protein isolate and β-gelatin;

[0017] The initiator is a combination of ammonium persulfate and n-dodecyl mercaptan or potassium persulfate and n-dodecyl mercaptan, wherein the mass ratio of ammonium persulfate or potassium persulfate to n-dodecyl mercaptan is (8-9):1;

[0018] The hard monomers of the base resin and the shell resin are a combination of methyl methacrylate and styrene, and the mass ratios of methyl methacrylate to styrene are (2-2.2):1 and (3-3.2):1 respectively;

[0019] The soft monomer is lauryl methacrylate; the acrylic epoxy monomer is any one of glycidyl methacrylate or glycidyl acrylate; and the acrylic carboxyl monomer is any one of methacrylic acid or acrylic acid.

[0020] The catalyst is tetrabutylammonium bromide; the emulsifier is any one or a combination of two or more of sodium vinyl sulfonate, acrylate monopolyethylene glycol ester, and terminal acrylate-based waterborne polyurethane.

[0021] The pH buffer is one or a combination of sodium bicarbonate or ammonium bicarbonate; the neutralizer is one or a combination of triethylamine and NN dimethylethanolamine.

[0022] The latex particles in the environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion include a core resin layer, a base resin layer and a shell resin layer from the inside to the outside, and the particle size of the latex particles is 170-200nm; the mass ratio of the core resin layer, the base resin layer and the shell resin layer is (1.4-1.5): (1.7-2.1): 1.

[0023] The environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion has high solid and low viscosity and uniform particle size distribution. After the varnish is formed into a film, the surface is smooth and refreshing, and the glossiness is more than 100%. The hardness and adhesion of the coating film reach 2H and 0 levels respectively. Its water resistance, salt spray resistance and hiding power are greatly improved compared with other acrylic emulsions, and can be used in high-end architectural coatings.

[0024] Beneficial effects of the present invention:

[0025] (1) The present invention uses a chemical method to organically combine a soft core resin, a base resin and a hard shell resin, utilizes particle design to orderly copolymerize vinyl (meth) acrylic monomers, and finally dissolves the base resin through neutralization with amine to form a hollow structure, thereby synthesizing a three-layer hollow acrylic resin emulsion. In the preparation process, by limiting the ratio between the core, base and shell resins and monomers, and adopting a pre-swelling method and an intermittent feeding method, firstly, the stability of the polymerization between the monomers is ensured, and the composition of the copolymer is well controlled; secondly, mutual penetration grafting occurs between the core, base and shell resins, which greatly improves the compatibility of the core, base and shell resins, effectively solves the stability of the acrylic emulsion and increases other comprehensive properties.

[0026] (2) The present invention introduces a hollow structure of alkaline resin by designing the molecular structure. The formation of the three-layer hollow resin structure causes the incident light source to undergo multiple refractions and scatterings, giving the coating film excellent hiding power. The products prepared with the hollow resin can be used for high-end architectural coatings and can also give the coating thermal insulation and other properties. Based on the cross-linking reaction mechanism of ketocarbonyl and amino groups, the functional monomer acetoacetoxyethyl methacrylate (AAEM) is first copolymerized to the main chain of acrylic resin, and then the natural substance protein macromolecule (containing a large number of amino groups on the molecular chain) is used as a cross-linking agent to cross-link with AAEM at room temperature as the amine gradually evaporates, forming a three-dimensional cross-linked network structure ( Figure 2 ), greatly improving the hardness of the resin coating. At the same time, the protein material is an environmentally friendly and non-toxic material, and also gives the characteristics of natural protein (such as smooth and comfortable coating, increased impact resistance); in addition, after the coating is self-crosslinked at room temperature, its glass transition temperature (Tg) is increased, but at the same time, the low-temperature film-forming property of the three-layer hollow acrylic emulsion is ensured, effectively solving the problem of hot stickiness and cold brittleness of ordinary acrylic emulsion.

[0027] (3) The present invention uses n-dodecyl mercaptan and ammonium (potassium) persulfate as an initiator and limits their ratio, which can significantly reduce the polymerization temperature of the reaction (compared with other acrylic resin emulsion polymerizations), greatly saving energy consumption and costs; and the preparation process of the present invention is simple, and no film-forming aid is added during the introduction of natural material protein in the synthesis process and the film-forming process, thereby reducing the amount of VOCs used, being green and environmentally friendly, and having broad market application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is a diagram of the structure of environmentally friendly room temperature self-crosslinking three-layer hollow resin emulsion particles.

[0030] Figure 2 This is a diagram showing the crosslinking reaction mechanism of an environmentally friendly, room temperature self-crosslinking three-layer hollow resin emulsion system.

[0031] Figure 3 The particle size distribution diagram of the environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion prepared in Example 1.

[0032] Figure 4 The particle size distribution diagram of the environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion prepared in Example 2.

[0033] Figure 5 The particle size distribution diagram of the environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion prepared in Example 4. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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.

[0035] Example 1

[0036] An environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion, calculated by mass parts as follows:

[0037] Soft monomer: lauryl methacrylate, 40 parts;

[0038] Hard monomers: methyl methacrylate and styrene, accounting for 48 parts and 16 parts respectively;

[0039] Acrylic epoxy monomer: glycidyl methacrylate, 5 parts;

[0040] Acrylic acid carboxyl monomer: methacrylic acid, 26 parts;

[0041] Ethyl acetoacetate methacrylate: 1.5 parts;

[0042] Protein: soy protein isolate, 1 portion;

[0043] Initiator: ammonium persulfate and n-dodecyl mercaptan, 1.2 parts;

[0044] Catalyst: tetrabutylammonium bromide, 0.1 part;

[0045] pH buffer: sodium bicarbonate, 0.5 parts;

[0046] Emulsifier: sodium vinyl sulfonate, 1.4 parts;

[0047] Deionized water: 130 parts;

[0048] Neutralizing agent: triethylamine, 5 parts.

[0049] The preparation process is:

[0050] (1) Deionized water, emulsifier and pH buffer were added to a 500 mL four-necked flask in sequence, heated to 45 °C in a water bath, and continuously stirred at a speed of 150 r / min;

[0051] (2) 10 parts of methyl methacrylate, 30 parts of lauryl methacrylate and 5 parts of glycidyl methacrylate were added to a 150 mL flask and mixed to obtain a core resin pre-emulsion A; tetrabutylammonium bromide, 6 parts of lauryl methacrylate, 20 parts of methyl methacrylate, 10 parts of styrene, 25 parts of methacrylic acid and 1.5 parts of ethyl acetoacetate methacrylate were added to a 150 mL flask and mixed to obtain a base resin pre-emulsion B; 4 parts of lauryl methacrylate, 18 parts of methyl methacrylate, 6 parts of styrene, 1 part of methacrylic acid, 0.27 parts of ammonium persulfate, 0.03 parts of n-dodecyl mercaptan and 1 part of soy protein isolate were added to a 150 mL flask and mixed to obtain a shell resin pre-emulsion C;

[0052] (3) 1 / 6 of the mixed solution of the core resin pre-emulsion A was uniformly added to a 500 mL four-necked flask, and after uniform stirring for 5 min, 0.054 parts of ammonium persulfate and 0.006 parts of n-dodecyl mercaptan were added. After keeping the temperature for 25 min, 0.324 parts of ammonium persulfate and 0.036 parts of n-dodecyl mercaptan were added, and then the remaining mixed solution of the pre-emulsion A was uniformly added dropwise for 45 min, and the temperature was kept for another 30 min;

[0053] (4) After the insulation is completed, 1 / 6 of the mixed solution of pre-emulsion B is added, and after uniform stirring for 5 minutes, 0.108 parts of ammonium persulfate and 0.012 parts of n-dodecyl mercaptan are added. After the insulation reaction for 25 minutes, 0.324 parts of ammonium persulfate and 0.036 parts of n-dodecyl mercaptan are added, and then the remaining mixed solution of pre-emulsion B is added dropwise at a very slow rate, and the addition time is maintained at 120 minutes. After the addition is completed, the insulation reaction is carried out for 30 minutes;

[0054] (5) Finally, slowly add the mixed solution of pre-emulsion C dropwise for 75 min, and keep the temperature for reaction for 2 h after the addition is completed;

[0055] (6) When the temperature reaches 40° C., triethylamine is added and stirred evenly, and the pH is adjusted to 8.5 to obtain an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion, the structure of which is as follows: Figure 1 shown.

[0056] Example 2

[0057] An environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion, calculated by mass parts as follows:

[0058] Soft monomer: lauryl methacrylate, 54.5 parts;

[0059] Hard monomers: methyl methacrylate and styrene, accounting for 58.2 parts and 18.8 parts respectively;

[0060] Acrylic epoxy monomer: glycidyl methacrylate, 6 parts;

[0061] Acrylic acid carboxyl monomer: methacrylic acid, 29.5 parts;

[0062] Ethyl acetoacetate methacrylate: 2 parts;

[0063] Protein: soy protein isolate, 2 servings;

[0064] Initiator: potassium persulfate and n-dodecyl mercaptan, 1.8 parts;

[0065] Catalyst: tetrabutylammonium bromide, 0.3 parts;

[0066] pH buffer: ammonium bicarbonate, 1 part;

[0067] Emulsifier: acrylate-terminated waterborne polyurethane, 2 parts;

[0068] Deionized water: 160 parts;

[0069] Neutralizer: NN dimethylethanolamine, 6 parts.

[0070] The preparation process is:

[0071] (1) Deionized water, emulsifier and pH buffer were added to a 500 mL four-necked flask in sequence, heated to 53 °C in a water bath, and continuously stirred mechanically at a speed of 200 r / min;

[0072] (2) 13 parts of methyl methacrylate, 38 parts of lauryl methacrylate and 6 parts of glycidyl methacrylate were added to a 150 mL flask and mixed to obtain a core resin pre-emulsion A; tetrabutylammonium bromide, 8.5 parts of lauryl methacrylate, 22.7 parts of methyl methacrylate, 11.3 parts of styrene, 28 parts of methacrylic acid and 2 parts of acetoacetoxyethyl methacrylate were added to a 150 mL flask and mixed to obtain a base resin pre-emulsion B; 8 parts of lauryl methacrylate, 22.5 parts of methyl methacrylate, 7.5 parts of styrene, 1.5 parts of methacrylic acid, 0.405 parts of potassium persulfate, 0.045 parts of n-dodecyl mercaptan and 2 parts of soy protein isolate were added to a 150 mL flask and mixed to obtain a shell resin pre-emulsion C;

[0073] (3) 1 / 6 of the mixed solution of the core resin pre-emulsion A was uniformly added to a 500 mL four-necked flask, and after uniform stirring for 5 min, 0.081 parts of potassium persulfate and 0.009 parts of n-dodecyl mercaptan were added. After keeping the temperature for 25 min, 0.486 parts of potassium persulfate and 0.054 parts of n-dodecyl mercaptan were added, and then the remaining mixed solution of the pre-emulsion A was uniformly added dropwise for 50 min, and then kept for 30 min;

[0074] (4) After the insulation is completed, 1 / 6 of the mixed solution of pre-emulsion B is added, and after uniform stirring for 5 minutes, 0.162 parts of potassium persulfate and 0.018 parts of n-dodecyl mercaptan are added. After the insulation reaction for 25 minutes, 0.486 parts of potassium persulfate and 0.054 parts of n-dodecyl mercaptan are added, and then the remaining mixed solution of pre-emulsion B is added dropwise at a very slow rate, and the addition time is maintained at 100 minutes. After the addition is completed, the insulation reaction is carried out for 30 minutes;

[0075] (5) Finally, slowly add the mixed solution of pre-emulsion C dropwise for 70 min, and keep the temperature for reaction for 1.5 h after the addition is completed;

[0076] (6) When the temperature reaches 40° C., NN dimethylethanolamine is added and stirred evenly, and the pH is adjusted to 9 to obtain an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion.

[0077] Example 3

[0078] An environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion, calculated by mass parts as follows:

[0079] Soft monomer: lauryl methacrylate, 49 parts;

[0080] Hard monomers: methyl methacrylate and styrene, accounting for 54 parts and 17.5 parts respectively;

[0081] Acrylic epoxy monomer: glycidyl acrylate, 5.5 parts;

[0082] Acrylic acid carboxyl monomer: acrylic acid, 28.3 parts;

[0083] Ethyl acetoacetate methacrylate: 1.8 parts;

[0084] Protein: β-gelatin, 1.5 parts;

[0085] Initiator: potassium persulfate and n-dodecyl mercaptan, 1.5 parts;

[0086] Catalyst: tetrabutylammonium bromide, 0.18 parts;

[0087] pH buffer: ammonium bicarbonate, 0.8 parts;

[0088] Emulsifier: acrylate-terminated waterborne polyurethane, 1.8 parts;

[0089] Deionized water: 152 parts;

[0090] Neutralizing agent: triethylamine, NN dimethylethanolamine, accounting for 4 parts and 2.5 parts respectively.

[0091] The preparation process is:

[0092] (1) Deionized water, emulsifier and pH buffer were added to a 500 mL four-necked flask in sequence, heated to 55 °C in a water bath, and continuously stirred at a speed of 180 r / min;

[0093] (2) 12 parts of methyl methacrylate, 35 parts of lauryl methacrylate and 5.5 parts of glycidyl acrylate were added to a 150 mL flask and mixed to obtain a core resin pre-emulsion A; tetrabutylammonium bromide, 8 parts of lauryl methacrylate, 21 parts of methyl methacrylate, 10.5 parts of styrene, 27 parts of acrylic acid and 1.8 parts of acetoacetoxyethyl methacrylate were added to a 150 mL flask and mixed to obtain a base resin pre-emulsion B; 6 parts of lauryl methacrylate, 21 parts of methyl methacrylate, 7 parts of styrene, 1.3 parts of acrylic acid, 0.335 parts of potassium persulfate, 0.04 parts of n-dodecyl mercaptan and 1.5 parts of β-gelatin were added to a 150 mL flask and mixed to obtain a shell resin pre-emulsion C;

[0094] (3) 1 / 6 of the mixed solution of the core resin pre-emulsion A was uniformly added to a 500 mL four-necked flask, and after uniform stirring for 5 min, 0.067 parts of potassium persulfate and 0.008 parts of n-dodecyl mercaptan were added. After keeping the temperature for 25 min, 0.4 parts of potassium persulfate and 0.05 parts of n-dodecyl mercaptan were added, and then the remaining mixed solution of the pre-emulsion A was uniformly added dropwise for 48 min, and the temperature was kept for another 30 min;

[0095] (4) After the insulation is completed, 1 / 6 of the mixed solution of pre-emulsion B is added, and after uniform stirring for 5 minutes, 0.135 parts of potassium persulfate and 0.015 parts of n-dodecyl mercaptan are added. After the insulation reaction for 25 minutes, 0.4 parts of potassium persulfate and 0.05 parts of n-dodecyl mercaptan are added, and then the remaining mixed solution of pre-emulsion B is added dropwise at a very slow rate, and the addition time is maintained at 110 minutes. After the addition is completed, the insulation reaction is carried out for 30 minutes;

[0096] (5) Finally, slowly add the mixed solution of pre-emulsion C dropwise for 65 min, and keep the temperature for reaction for 2.5 h after the addition is completed;

[0097] (6) When the temperature reaches 40° C., triethylamine and NN dimethylethanolamine are added and stirred evenly, and the pH is adjusted to 8.7 to obtain an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion.

[0098] Example 4

[0099] An environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion, calculated by mass parts as follows:

[0100] Soft monomer: lauryl methacrylate, 46.5 parts;

[0101] Hard monomers: methyl methacrylate and styrene, accounting for 54.3 parts and 18 parts respectively;

[0102] Acrylic epoxy monomer: glycidyl acrylate, 5.6 parts;

[0103] Acrylic acid carboxyl monomer: methacrylic acid, 27.2 parts;

[0104] Ethyl acetoacetate methacrylate: 1.6 parts;

[0105] Protein: β-gelatin, 1.3 parts;

[0106] Initiator: ammonium persulfate and n-dodecyl mercaptan, 1.56 parts;

[0107] Catalyst: tetrabutylammonium bromide, 0.2 parts;

[0108] pH buffer: sodium bicarbonate, ammonium bicarbonate, 0.3 parts and 0.4 parts respectively;

[0109] Emulsifier: acrylate monopolyethylene glycol ester, 1.6 parts;

[0110] Deionized water: 150 parts;

[0111] Neutralizing agent: NN dimethylethanolamine, 6.2 parts.

[0112] The preparation process is:

[0113] (1) Deionized water, emulsifier and pH buffer were added to a 500 mL four-necked flask in sequence, heated to 52 °C in a water bath, and continuously stirred mechanically at a speed of 200 r / min;

[0114] (2) 11.5 parts of methyl methacrylate, 33.5 parts of lauryl methacrylate and 5.6 parts of glycidyl acrylate were added to a 150 mL flask and mixed to obtain a core resin pre-emulsion A; tetrabutylammonium bromide, 7.5 parts of lauryl methacrylate, 22.4 parts of methyl methacrylate, 11.2 parts of styrene, 26 parts of methacrylic acid and 1.6 parts of ethyl acetoacetate methacrylate were added to a 150 mL flask and mixed to obtain a base resin pre-emulsion B; 5.5 parts of lauryl methacrylate, 20.4 parts of methyl methacrylate, 6.8 parts of styrene, 1.2 parts of methacrylic acid, 0.35 parts of ammonium persulfate, 0.04 parts of n-dodecyl mercaptan and 1.3 parts of β-gelatin were added to a 150 mL flask and mixed to obtain a shell resin pre-emulsion C;

[0115] (3) 1 / 6 of the mixed solution of the core resin pre-emulsion A was uniformly added to a 500 mL four-necked flask, and after uniform stirring for 5 min, 0.07 parts of ammonium persulfate and 0.008 parts of n-dodecyl mercaptan were added. After keeping the temperature for 25 min, 0.42 parts of ammonium persulfate and 0.048 parts of n-dodecyl mercaptan were added, and then the remaining mixed solution of the pre-emulsion A was uniformly added dropwise for 45 min, and the temperature was kept for another 30 min;

[0116] (4) After the insulation is completed, 1 / 6 of the mixed solution of pre-emulsion B is added, and after uniform stirring for 5 minutes, 0.14 parts of ammonium persulfate and 0.016 parts of n-dodecyl mercaptan are added. After the insulation reaction for 25 minutes, 0.42 parts of ammonium persulfate and 0.048 parts of n-dodecyl mercaptan are added, and then the remaining mixed solution of pre-emulsion B is added dropwise at a very slow rate, and the addition time is maintained at 100 minutes. After the addition is completed, the insulation reaction is carried out for 30 minutes;

[0117] (5) Finally, slowly add the mixed solution of pre-emulsion C dropwise for 65 min, and keep the temperature for reaction for 2 h after the addition is completed;

[0118] (6) When the temperature reaches 40° C., NN dimethylethanolamine is added and stirred evenly, and the pH is adjusted to 8.8 to obtain an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion.

[0119] Example 5

[0120] An environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion, calculated by mass parts as follows:

[0121] Soft monomer: lauryl methacrylate, 48 parts;

[0122] Hard monomers: methyl methacrylate and styrene, accounting for 56 parts and 18.5 parts respectively;

[0123] Acrylic epoxy monomer: glycidyl methacrylate, 5.8 parts;

[0124] Acrylic acid carboxyl monomer: methacrylic acid, 29 parts;

[0125] Ethyl acetoacetate methacrylate: 1.7 parts;

[0126] Protein: soy protein isolate, 1 portion;

[0127] Initiator: potassium persulfate and n-dodecyl mercaptan, 1.6 parts;

[0128] Catalyst: tetrabutylammonium bromide, 0.3 parts;

[0129] pH buffer: ammonium bicarbonate, 0.8 parts;

[0130] Emulsifier: sodium vinyl sulfonate, acrylate-terminated waterborne polyurethane, 0.8 parts and 0.8 parts respectively;

[0131] Deionized water: 155 parts;

[0132] Neutralizing agent: triethylamine, 6.5 parts.

[0133] The preparation process is:

[0134] (1) Deionized water, emulsifier and pH buffer were added to a 500 mL four-necked flask in sequence, heated to 48 °C in a water bath, and continuously stirred at 200 r / min;

[0135] (2) 12 parts of methyl methacrylate, 34.5 parts of lauryl methacrylate and 5.8 parts of glycidyl methacrylate were added to a 150 mL flask and mixed to obtain a core resin pre-emulsion A; tetrabutylammonium bromide, 7 parts of lauryl methacrylate, 23 parts of methyl methacrylate, 11.5 parts of styrene, 27.2 parts of methacrylic acid and 1.7 parts of acetoacetoxyethyl methacrylate were added to a 150 mL flask and mixed to obtain a base resin pre-emulsion B; 6.5 parts of lauryl methacrylate, 21 parts of methyl methacrylate, 7 parts of styrene, 1.8 parts of methacrylic acid, 0.36 parts of potassium persulfate, 0.04 parts of n-dodecyl mercaptan and 1 part of soy protein isolate were added to a 150 mL flask and mixed to obtain a shell resin pre-emulsion C;

[0136] (3) 1 / 6 of the mixed solution of the core resin pre-emulsion A was uniformly added to a 500 mL four-necked flask, and after uniform stirring for 5 min, 0.072 parts of potassium persulfate and 0.008 parts of n-dodecyl mercaptan were added. After keeping the temperature for 25 min, 0.43 parts of potassium persulfate and 0.05 parts of n-dodecyl mercaptan were added, and then the remaining mixed solution of the pre-emulsion A was uniformly added dropwise for 45 min, and the temperature was kept for another 30 min;

[0137] (4) After the insulation is completed, 1 / 6 of the mixed solution of pre-emulsion B is added, and after uniform stirring for 5 minutes, 0.144 parts of potassium persulfate and 0.016 parts of n-dodecyl mercaptan are added. After the insulation reaction is continued for 25 minutes, 0.42 parts of potassium persulfate and 0.05 parts of n-dodecyl mercaptan are added, and then the remaining mixed solution of pre-emulsion B is added dropwise at a very slow rate, and the addition time is maintained at 100 minutes. After the addition is completed, the insulation reaction is continued for 30 minutes;

[0138] (5) Finally, slowly add the mixed solution of pre-emulsion C dropwise for 65 min, and keep the temperature for reaction for 1.5 h after the addition is completed;

[0139] (6) When the temperature reaches 40° C., triethylamine is added and stirred evenly, and the pH is adjusted to 8.5 to obtain an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion.

[0140] Comparative Example 1

[0141] An environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion, calculated by mass parts as follows:

[0142] Soft monomer: lauryl methacrylate, 20 parts;

[0143] Hard monomers: methyl methacrylate and styrene, accounting for 68 parts and 16 parts respectively;

[0144] Acrylic epoxy monomer: glycidyl methacrylate, 5 parts;

[0145] Acrylic acid carboxyl monomer: methacrylic acid, 26 parts;

[0146] Ethyl acetoacetate methacrylate: 1.5 parts;

[0147] Protein: soy protein isolate, 1 portion;

[0148] Initiator: ammonium persulfate and n-dodecyl mercaptan, 1.2 parts;

[0149] pH buffer: sodium bicarbonate, 0.5 parts;

[0150] Catalyst: tetrabutylammonium bromide, 0.1 part;

[0151] Emulsifier: sodium vinyl sulfonate, 1.4 parts;

[0152] Deionized water: 130 parts;

[0153] Neutralizing agent: triethylamine, 4 parts.

[0154] The preparation process is:

[0155] (1) Deionized water, emulsifier and pH buffer were added to a 500 mL four-necked flask in sequence, heated to 45 °C in a water bath, and continuously stirred at a speed of 150 r / min;

[0156] (2) 30 parts of methyl methacrylate, 10 parts of lauryl methacrylate and 5 parts of glycidyl methacrylate were added to a 150 mL flask and mixed to obtain a core resin pre-emulsion A; tetrabutylammonium bromide, 6 parts of lauryl methacrylate, 20 parts of methyl methacrylate, 10 parts of styrene, 25 parts of methacrylic acid and 1.5 parts of ethyl acetoacetate methacrylate were added to a 150 mL flask and mixed to obtain a base resin pre-emulsion B; 4 parts of lauryl methacrylate, 18 parts of methyl methacrylate, 6 parts of styrene, 1 part of methacrylic acid, 0.27 parts of ammonium persulfate, 0.03 parts of n-dodecyl mercaptan and 1 part of soy protein isolate were added to a 150 mL flask and mixed to obtain a shell resin pre-emulsion C;

[0157] (3) 1 / 6 of the mixed solution of the core resin pre-emulsion A was uniformly added to a 500 mL four-necked flask, and after uniform stirring for 5 min, 0.054 parts of ammonium persulfate and 0.006 parts of n-dodecyl mercaptan were added. After keeping the temperature for 25 min, 0.324 parts of ammonium persulfate and 0.036 parts of n-dodecyl mercaptan were added, and then the remaining mixed solution of the pre-emulsion A was uniformly added dropwise for 45 min, and the temperature was kept for another 30 min;

[0158] (4) After the insulation is completed, 1 / 6 of the mixed solution of pre-emulsion B is added, and after uniform stirring for 5 minutes, 0.108 parts of ammonium persulfate and 0.012 parts of n-dodecyl mercaptan are added. After the insulation reaction for 25 minutes, 0.324 parts of ammonium persulfate and 0.036 parts of n-dodecyl mercaptan are added, and then the remaining mixed solution of pre-emulsion B is added dropwise at a very slow rate, and the addition time is maintained at 120 minutes. After the addition is completed, the insulation reaction is carried out for 30 minutes;

[0159] (5) Finally, slowly add the mixed solution of pre-emulsion C dropwise for 75 min, and keep the temperature for reaction for 2 h after the addition is completed;

[0160] (6) When the temperature reaches 40° C., triethylamine is added and stirred evenly, and the pH is adjusted to 8.5 to obtain an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion.

[0161] Comparative Example 2

[0162] A three-layer hollow acrylic resin emulsion, calculated by mass parts as follows:

[0163] Soft monomer: lauryl methacrylate, 54.5 parts;

[0164] Hard monomers: methyl methacrylate and styrene, accounting for 58.2 parts and 18.8 parts respectively;

[0165] Acrylic epoxy monomer: glycidyl methacrylate, 6 parts;

[0166] Acrylic acid carboxyl monomer: methacrylic acid, 29.5 parts;

[0167] Ethyl acetoacetate methacrylate: 2 parts;

[0168] Initiator: potassium persulfate and n-dodecyl mercaptan, 1.8 parts;

[0169] Catalyst: tetrabutylammonium bromide, 0.15 parts;

[0170] pH buffer: ammonium bicarbonate, 1 part;

[0171] Emulsifier: acrylate-terminated waterborne polyurethane, 2 parts;

[0172] Deionized water: 160 parts;

[0173] Neutralizer: NN dimethylethanolamine, 6 parts.

[0174] The preparation process is:

[0175] (1) Deionized water, emulsifier and pH buffer were added to a 500 mL four-necked flask in sequence, heated to 53 °C in a water bath, and continuously stirred mechanically at a speed of 200 r / min;

[0176] (2) 13 parts of methyl methacrylate, 38 parts of lauryl methacrylate and 6 parts of glycidyl methacrylate were added to a 150 mL flask and mixed to obtain a core resin pre-emulsion A; tetrabutylammonium bromide, 8.5 parts of lauryl methacrylate, 22.7 parts of methyl methacrylate, 11.3 parts of styrene, 28 parts of methacrylic acid and 2 parts of acetoacetoxyethyl methacrylate were added to a 150 mL flask and mixed to obtain a base resin pre-emulsion B; 8 parts of lauryl methacrylate, 22.5 parts of methyl methacrylate, 7.5 parts of styrene, 1.5 parts of methacrylic acid, 0.405 parts of potassium persulfate and 0.045 parts of n-dodecyl mercaptan were added to a 150 mL flask and mixed to obtain a shell resin pre-emulsion C;

[0177] (3) 1 / 6 of the mixed solution of the core resin pre-emulsion A was uniformly added to a 500 mL four-necked flask, and after uniform stirring for 5 min, 0.081 parts of potassium persulfate and 0.009 parts of n-dodecyl mercaptan were added. After keeping the temperature for 25 min, 0.486 parts of potassium persulfate and 0.054 parts of n-dodecyl mercaptan were added, and then the remaining mixed solution of the pre-emulsion A was uniformly added dropwise for 50 min, and then kept for 30 min;

[0178] (4) After the insulation is completed, 1 / 6 of the mixed solution of pre-emulsion B is added, and after uniform stirring for 5 minutes, 0.162 parts of potassium persulfate and 0.018 parts of n-dodecyl mercaptan are added. After the insulation reaction for 25 minutes, 0.486 parts of potassium persulfate and 0.054 parts of n-dodecyl mercaptan are added, and then the remaining mixed solution of pre-emulsion B is added dropwise at a very slow rate, and the addition time is maintained at 100 minutes. After the addition is completed, the insulation reaction is carried out for 30 minutes;

[0179] (5) Finally, slowly add the mixed solution of pre-emulsion C dropwise for 70 min, and keep the temperature for reaction for 1.5 h after the addition is completed;

[0180] (6) When the temperature reaches 40° C., NN dimethylethanolamine is added and stirred evenly, and the pH is adjusted to 9 to obtain a three-layer hollow acrylic resin emulsion.

[0181] Comparative Example 3

[0182] An acrylic resin emulsion, calculated by weight parts as follows:

[0183] Soft monomer: lauryl methacrylate, 39 parts;

[0184] Hard monomers: methyl methacrylate and styrene, accounting for 32 parts and 7 parts respectively;

[0185] Acrylic epoxy monomer: glycidyl acrylate, 5.5 parts;

[0186] Acrylic acid carboxyl monomer: acrylic acid, 8.3 parts;

[0187] Protein: β-gelatin, 1.5 parts;

[0188] Initiator: potassium persulfate and n-dodecyl mercaptan, 0.9 parts;

[0189] pH buffer: ammonium bicarbonate, 0.5 parts;

[0190] Emulsifier: acrylate-terminated waterborne polyurethane, 1.2 parts;

[0191] Deionized water: 91 parts;

[0192] Neutralizing agent: triethylamine, NN dimethylethanolamine, accounting for 2 parts and 1.6 parts respectively.

[0193] The preparation process is:

[0194] (1) Deionized water, emulsifier and pH buffer were added to a 500 mL four-necked flask in sequence, heated to 55 °C in a water bath, and continuously stirred at a speed of 180 r / min;

[0195] (2) 12 parts of methyl methacrylate, 35 parts of lauryl methacrylate and 5.5 parts of glycidyl acrylate were added to a 150 mL flask and mixed to obtain a core resin pre-emulsion A; 6 parts of lauryl methacrylate, 21 parts of methyl methacrylate, 7 parts of styrene, 1.3 parts of acrylic acid, 0.335 parts of potassium persulfate, 0.04 parts of n-dodecyl mercaptan and 1.5 parts of β-gelatin were added to a 150 mL flask and mixed to obtain a shell resin pre-emulsion C;

[0196] (3) 1 / 6 of the mixed solution of the core resin pre-emulsion A was uniformly added to a 500 mL four-necked flask, and after uniform stirring for 5 min, 0.067 parts of potassium persulfate and 0.008 parts of n-dodecyl mercaptan were added. After keeping the temperature for 25 min, 0.4 parts of potassium persulfate and 0.05 parts of n-dodecyl mercaptan were added, and then the remaining mixed solution of the pre-emulsion A was uniformly added dropwise for 48 min, and the temperature was kept for another 30 min;

[0197] (4) Finally, slowly add the mixed solution of pre-emulsion C dropwise for 65 min, and keep the temperature for reaction for 2.5 h after the addition is completed;

[0198] (5) When the temperature reaches 40°C, add triethylamine and NN dimethylethanolamine and stir evenly, and adjust the pH to 8.7 to obtain an acrylic resin emulsion.

[0199] Comparative Example 4

[0200] An environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion, calculated by mass parts as follows:

[0201] Soft monomer: lauryl methacrylate, 46.5 parts;

[0202] Hard monomers: methyl methacrylate and styrene, accounting for 54.3 parts and 18 parts respectively;

[0203] Acrylic epoxy monomer: glycidyl acrylate, 5.6 parts;

[0204] Acrylic acid carboxyl monomer: methacrylic acid, 27.2 parts;

[0205] Ethyl acetoacetate methacrylate: 1.6 parts;

[0206] Protein: β-gelatin, 1.3 parts;

[0207] Initiator: ammonium persulfate, 1.56 parts;

[0208] pH buffer: sodium bicarbonate, ammonium bicarbonate, 0.3 parts and 0.4 parts respectively;

[0209] Catalyst: tetrabutylammonium bromide, 0.2 parts;

[0210] Emulsifier: acrylate monopolyethylene glycol ester, 1.6 parts;

[0211] Deionized water: 150 parts;

[0212] Neutralizing agent: NN dimethylethanolamine, 6.2 parts.

[0213] The preparation process is:

[0214] (1) Deionized water, emulsifier and pH buffer were added to a 500 mL four-necked flask in sequence, heated to 78 °C in a water bath, and continuously stirred mechanically at a speed of 200 r / min;

[0215] (2) 11.5 parts of methyl methacrylate, 33.5 parts of lauryl methacrylate and 5.6 parts of glycidyl acrylate were added to a 150 mL flask and mixed to obtain a core resin pre-emulsion A; tetrabutylammonium bromide, 7.5 parts of lauryl methacrylate, 22.4 parts of methyl methacrylate, 11.2 parts of styrene, 26 parts of methacrylic acid and 1.6 parts of ethyl acetoacetate methacrylate were added to a 150 mL flask and mixed to obtain a base resin pre-emulsion B; 5.5 parts of lauryl methacrylate, 20.4 parts of methyl methacrylate, 6.8 parts of styrene, 1.2 parts of methacrylic acid, 0.39 parts of ammonium persulfate and 1.3 parts of β-gelatin were added to a 150 mL flask and mixed to obtain a shell resin pre-emulsion C;

[0216] (3) 1 / 6 of the mixed solution of the core resin pre-emulsion A was uniformly added to a 500 mL four-necked flask, and after uniform stirring for 5 minutes, 0.078 parts of ammonium persulfate was added. After keeping the temperature for 25 minutes, 0.468 parts of ammonium persulfate was added, and then the remaining mixed solution of the pre-emulsion A was uniformly added dropwise for 45 minutes, and then kept for 30 minutes;

[0217] (4) After the insulation is completed, 1 / 6 of the mixed solution of pre-emulsion B is added, and after stirring at a uniform speed for 5 minutes, 0.312 parts of ammonium persulfate are added. After the insulation reaction for 25 minutes, 0.468 parts of ammonium persulfate are added, and then the remaining mixed solution of pre-emulsion B is added dropwise at a very slow rate. The addition time is maintained at 100 minutes. After the addition is completed, the insulation reaction is continued for 30 minutes;

[0218] (5) Finally, slowly add the mixed solution of pre-emulsion C dropwise for 65 min, and keep the temperature for reaction for 2 h after the addition is completed;

[0219] (6) When the temperature reaches 40° C., NN dimethylethanolamine is added and stirred evenly, and the pH is adjusted to 8.8 to obtain an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion.

[0220] Comparative Example 5

[0221] An environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion, calculated by mass parts as follows:

[0222] Soft monomer: lauryl methacrylate, 48 parts;

[0223] Hard monomers: methyl methacrylate and styrene, accounting for 56 parts and 18.5 parts respectively;

[0224] Acrylic epoxy monomer: glycidyl methacrylate, 5.8 parts;

[0225] Acrylic acid carboxyl monomer: methacrylic acid, 29 parts;

[0226] Ethyl acetoacetate methacrylate: 1.7 parts;

[0227] Protein: soy protein isolate, 1 portion;

[0228] Initiator: potassium persulfate and n-dodecyl mercaptan, 1.6 parts;

[0229] pH buffer: ammonium bicarbonate, 0.8 parts;

[0230] Catalyst: tetrabutylammonium bromide, 0.3 parts;

[0231] Emulsifier: sodium lauryl sulfate, 1.6 parts;

[0232] Deionized water: 155 parts;

[0233] Neutralizing agent: triethylamine, 6.5 parts.

[0234] The preparation process is:

[0235] (1) Deionized water, emulsifier and pH buffer were added to a 500 mL four-necked flask in sequence, heated to 48 °C in a water bath, and continuously stirred at 200 r / min;

[0236] (2) 12 parts of methyl methacrylate, 34.5 parts of lauryl methacrylate and 5.8 parts of glycidyl methacrylate were added to a 150 mL flask and mixed to obtain a core resin pre-emulsion A; tetrabutylammonium bromide, 7 parts of lauryl methacrylate, 23 parts of methyl methacrylate, 11.5 parts of styrene, 27.2 parts of methacrylic acid and 1.7 parts of acetoacetoxyethyl methacrylate were added to a 150 mL flask and mixed to obtain a base resin pre-emulsion B; 6.5 parts of lauryl methacrylate, 21 parts of methyl methacrylate, 7 parts of styrene, 1.8 parts of methacrylic acid, 0.36 parts of potassium persulfate, 0.04 parts of n-dodecyl mercaptan and 1 part of soy protein isolate were added to a 150 mL flask and mixed to obtain a shell resin pre-emulsion C;

[0237] (3) 1 / 6 of the mixed solution of the core resin pre-emulsion A was uniformly added to a 500 mL four-necked flask, and after uniform stirring for 5 min, 0.072 parts of potassium persulfate and 0.008 parts of n-dodecyl mercaptan were added. After keeping the temperature for 25 min, 0.43 parts of potassium persulfate and 0.05 parts of n-dodecyl mercaptan were added, and then the remaining mixed solution of the pre-emulsion A was uniformly added dropwise for 45 min, and the temperature was kept for another 30 min;

[0238] (4) After the insulation is completed, 1 / 6 of the mixed solution of pre-emulsion B is added, and after uniform stirring for 5 minutes, 0.144 parts of potassium persulfate and 0.016 parts of n-dodecyl mercaptan are added. After the insulation reaction is continued for 25 minutes, 0.42 parts of potassium persulfate and 0.05 parts of n-dodecyl mercaptan are added, and then the remaining mixed solution of pre-emulsion B is added dropwise at a very slow rate, and the addition time is maintained at 100 minutes. After the addition is completed, the insulation reaction is continued for 30 minutes;

[0239] (5) Finally, slowly add the mixed solution of pre-emulsion C dropwise for 65 min, and keep the temperature for reaction for 1.5 h after the addition is completed;

[0240] (6) When the temperature reaches 40° C., triethylamine is added and stirred evenly, and the pH is adjusted to 8.5 to obtain an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion.

[0241] Test Case

[0242] First, the particle sizes of the environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsions prepared in Examples 1, 2 and 4 were measured. Figure 3-5 As shown. Figure 3 It can be seen that the average particle size of the environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion prepared in Example 1 is 175nm; Figure 4 It can be seen that the average particle size of the environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion prepared in Example 2 is 189nm; Figure 5 It can be seen that the average particle size of the environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion prepared in Example 4 is 192nm; in order to further study the environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion prepared by the present invention, the present invention also tests the emulsions and coating properties of Examples 1 to 5 and Comparative Examples 1 to 5 accordingly, and the test method is as follows:

[0243] 1. Emulsion stability test

[0244] (1) Mechanical stability test: First, filter the emulsion with a 100-mesh screen, then vigorously stir it at 5000 rpm for 10 minutes in a power agitator, and then filter it with a 100-mesh screen. If no gel appears, the emulsion has good mechanical properties and passes the test. If gel appears, dry the filtered gel in an oven at 105°C to constant weight and weigh it. The more dry coagulants there are, the worse the mechanical stability.

[0245] (2) Freezing stability test: Place 50 mL of the emulsion sample into a cylindrical plastic container or glass container of about 100 mL, taking care not to mix in bubbles. Cover the container with a lid and seal it. Place it in a -20±2°C low-temperature oven. Take it out after 18 hours and place it in a 25±2°C constant temperature oven for 6 hours. Repeat this process five times. Open the container and stir it with a glass rod. Observe the sample for any abnormalities such as lumps or gels. Use a glass rod to spread the sample on a glass plate into a uniform thin layer and observe for the presence of flocs. If there are no flocs, the sample passes the test.

[0246] (3) Storage stability test: The prepared emulsion sample was placed in a 50°C oven and kept at a constant temperature for 2 weeks. The sample was taken out and placed at room temperature for observation. If no stratification, gelation, etc. was observed, the sample passed the test.

[0247] (4) Dilution stability test: dilute and mix the emulsion sample in the ratio of emulsion: water = 1:10, and place it for 48 hours. If no demulsification or stratification occurs, the test is passed.

[0248] 2. Coating performance test

[0249] (1) Test of coating surface drying time: The emulsion prepared in the example was evenly applied on a polytetrafluoroethylene plate, dried at a constant temperature of 25° C., and the coating surface drying time was tested according to the method of GB1728-79.

[0250] (2) Coating hardness test: The hardness of the emulsion coating prepared in the example was tested according to the method of GB / T6739-2006.

[0251] (3) Impact resistance test of coating film: The impact resistance of the emulsion coating film prepared in the example was tested according to the method of GB / T1732-1993.

[0252] (4) Coating adhesion test: The adhesion of the emulsion coating prepared in the examples was tested according to the method of GB / T9286-1998.

[0253] (5) Film gloss test: According to GB / T9754-2007 standard, the gloss of the emulsion film in the example was tested using the 60-degree specular gloss measurement method.

[0254] (6) Water resistance test of coating film: GB / T1733-1993 standard was used to test the water resistance of the emulsion coating film in the example. If the coating film did not bubble or fall off within 96 hours and slight discoloration was allowed, it was considered to have passed the test.

[0255] Among them, the difference between comparative example 1 and embodiment 1 is that the core resin of comparative example 1 has more hard monomers and less soft monomers, and other components remain unchanged; the difference between comparative example 2 and embodiment 2 is that no protein is added to the shell resin of comparative example 2, and other components remain unchanged; the difference between comparative example 3 and embodiment 3 is that there is no alkali resin in comparative example 3, and other components remain unchanged; the difference between comparative example 4 and embodiment 4 is that the initiator added in comparative example 4 does not contain dodecyl mercaptan, and other components remain unchanged; the difference between comparative example 5 and embodiment 5 is that the emulsifier in comparative example 5 is sodium dodecyl sulfate, and other components remain unchanged. The above test results are shown in Table 1.

[0256] Table 1

[0257]

[0258]

[0259] In order to further examine the hiding power of the three-layer hollow acrylic resin emulsion of the present invention as the main film-forming material in the coating, Example 3 and Comparative Example 3 and the commercially available emulsion ALBERDINGK@AC 2043 were ground by mixed vibration at high speed according to the method in Formula Table 2, and the coating films were dried and tested for hiding power. The test results are shown in Table 3.

[0260] Testing method: Take an appropriate amount of ground coating and place it on one end of a standard black and white cardboard, use an automatic coating machine to quickly coat it, place it under a certain temperature until the surface is dry, use a spectrophotometer to measure the reflectivity of the blackboard and whiteboard, and use the contrast ratio to reflect the hiding power of the coating. The calculation is as follows:

[0261] Contrast ratio = (blackboard reflectivity / whiteboard reflectivity) × 100%. The larger the contrast ratio, the better the covering power of the paint, which means the better the covering power of the acrylic resin emulsion.

[0262] Table 2 Experimental formula using mixed vibration high-speed grinding

[0263] raw material wt / % Acrylic Emulsion 63 Titanium dioxide 35 BYK-025 water-based defoamer 0.5 BYK-341 water-based substrate wetting agent 0.8 BYK-154 aqueous dispersant 1.3

[0264] Table 3 Hiding power test results

[0265] raw material Hiding power / % Example 3 90 Comparative Example 3 73 Commercially available 70

[0266] Table 3 shows the paint films prepared using Example 3, Comparative Example 3 and the common commercially available emulsion ALBERDINGK@AC 2043 as the main film-forming substances and the formula in Table 2. From the test results of the hiding power experiment, it can be seen that the paint film with the resin emulsion prepared by the patent application as the main film-forming substance has a hiding power of 90%, which is much higher than that of the paint film with Comparative Example 3 and the commercially available emulsion ALBERDINGK@AC 2043 as the main film-forming substance.

[0267] The experimental data tested in Table 1 were analyzed as follows: The patent of this application uses a chemical method to organically combine the soft core resin, the base resin and the hard shell resin. During the preparation process, by limiting the ratio between the core, base and shell resins and monomers, and adopting the pre-swelling method and intermittent feeding method, an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion is synthesized. The solid content is as high as about 52%, the emulsion viscosity is 65KU, the coating surface drying time is 25min-28min, the hardness and impact resistance are as high as 2H and 55kg.cm respectively, and the gloss of the coating is about 110°, which effectively solves the technical problems of high solid and low viscosity of the emulsion, high hardness and high flexibility of the coating, poor surface gloss and water resistance. 1) From Example 1 and Comparative Example 1, the core resin of Comparative Example 1 has a large amount of hard monomers and a small amount of soft monomers, and the other components remain unchanged. Although the hardness of the prepared resin is high / 3H, the impact resistance of the coating is much lower than that of the coating of Comparative Example 1 (40kg.cm<55kg.cm), which shows that the problem of high hardness and high flexibility of the coating can be effectively solved by limiting the ratio of soft and hard monomers in the present application. 2) From Example 2 and Comparative Example 2, no protein is added to the shell resin of Comparative Example 2, and the other components remain unchanged. The hardness of the coating after drying is only HB, which is significantly lower than the hardness / 2H of the coating of Example 2. The adhesion of the coating and the smoothness of the surface are also reduced, which shows that the protein in the present application can be used as a cross-linking agent, and cross-links with AAEM at room temperature as the amine volatilizes, thereby improving the hardness and other mechanical properties of the coating and giving the coating some protein characteristics. 3) From Example 3 and Comparative Example 3, there is no alkali resin in Comparative Example 3, and other components remain unchanged. The hardness and adhesion of the resin coating are H and 2 respectively, and the water resistance is also poor, indicating that the alkali resin is very important for improving the comprehensive performance of the resin. In addition, from the experimental results of the hiding power tested in Table 3, the hiding power of the coating prepared by the resin emulsion of Comparative Example 3 as the main film-forming material is only 73%, which is much lower than the hiding power of the coating prepared by the resin emulsion of Example 3 as the main film-forming material, indicating that the hollow alkali resin can refract and reflect light, effectively reducing the incidence of light and improving the hiding power of the coating on the substrate. 4) From Example 4 and Comparative Example 4, the initiator added in Comparative Example 4 does not contain dodecyl mercaptan, and other components remain unchanged. The performance of the resin emulsion and the coating has not changed, but the temperature of the synthetic resin emulsion is relatively high, indicating that the addition of dodecyl mercaptan can reduce the reaction energy of the system and save costs.5) From the perspective of implementation 5 and comparative example 5, the emulsifier in comparative example 5 is sodium dodecyl sulfate, and the mechanical stability, freezing stability, storage stability and water resistance of the resin emulsion have not passed. This is because ordinary emulsifiers are prone to demulsification in certain environments and migrate during the drying process of the coating, thereby reducing the water resistance of the coating. The emulsifier used in the present invention can react with the vinyl monomer and connect to the main chain of the molecule without demulsification. Therefore, it has good stability and water resistance.

[0268] In summary, the environmentally friendly room temperature self-crosslinking three-layer hollow acrylic emulsion prepared by the patent application can effectively solve the technical problems of low hardness and poor hiding power of water-based acrylic resin emulsion after film formation. The emulsion has high solid and low viscosity, uniform particle size distribution, and the coating prepared with it has strong hiding power and high gloss.

[0269] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion, It is characterized in that The following steps are included (1) Mixing soft monomers, hard monomers and acrylic epoxy monomers uniformly to obtain a core resin pre-emulsion; mixing catalysts, soft monomers, hard monomers, acrylic carboxyl monomers and acetoacetoxyethyl methacrylate uniformly to obtain a base resin pre-emulsion; mixing soft monomers, hard monomers, acrylic carboxyl monomers, initiators and proteins uniformly to obtain a shell resin pre-emulsion; and mixing deionized water, an emulsifier and a pH buffer uniformly to obtain an emulsifier solution; (2) adding the core resin pre-emulsion and the initiator into the emulsifier solution by intermittent feeding; (3) adding the alkaline resin pre-emulsion and the initiator to the solution of step (2) by intermittent feeding; (4) adding the shell resin pre-emulsion to the solution of step (3) to react, and adding a neutralizing agent after the reaction is completed to obtain an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion; The mass parts of the raw materials of each component in the preparation method are: 40-54.5 parts of soft monomer, 64-77 parts of hard monomer, 5-6 parts of acrylic epoxy monomer, 26-29.5 parts of acrylic carboxyl monomer, 1.5-2 parts of acetoacetoxyethyl methacrylate, 1-2 parts of protein, 1.2-1.8 parts of initiator, 0.1-0.3 parts of catalyst, 1.4-2 parts of emulsifier, 0.5-1 parts of pH buffer, 130-160 parts of deionized water, and 5-6.5 parts of neutralizer; The emulsifier is any one or a combination of two or more of sodium vinyl sulfonate, monopolyethylene glycol acrylate, and terminal acrylate-based waterborne polyurethane.

2. The method for preparing the environment-friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion according to claim 1, It is characterized in that The preparation method of each solution in step (1) is: Core resin pre-emulsion: 0.69-0.75 times of soft monomer, 0.15-0.17 times of hard monomer and acrylic epoxy monomer are uniformly mixed to obtain core resin pre-emulsion; Alkaline resin pre-emulsion: the catalyst, 0.15-0.16 times of soft monomer, 0.44-0.47 times of hard monomer, 0.94-0.97 times of acrylic acid carboxyl monomer and acetoacetoxyethyl methacrylate are uniformly mixed to obtain the alkaline resin pre-emulsion; Shell resin pre-emulsion: 0.10-0.15 times of soft monomer, 0.37-0.39 times of hard monomer, 0.03-0.05 times of acrylic acid carboxyl monomer, 0.25 times of initiator and protein are mixed evenly to obtain shell resin pre-emulsion; Emulsifier solution: heat deionized water, emulsifier and pH buffer to 40-55°C and stir to dissolve to obtain an emulsifier solution; the above-mentioned "times" are calculated based on the proportion of the corresponding monomers in the raw materials.

3. The method for preparing the environment-friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion according to claim 2, It is characterized in that The intermittent feeding step in step (2) is as follows: add 1 / 7-1 / 5 of the core resin pre-emulsion to the emulsifier solution, stir at a constant speed for 3-8 minutes, then add 1 / 40-3 / 40 of the initiator, keep the mixture warm for 15-25 minutes, then add 1 / 5-2 / 5 of the initiator, then dropwise add the remaining core resin pre-emulsion at a constant speed for 45-50 minutes, and keep the mixture warm for 20-40 minutes after the addition is completed.

4. The method for preparing the environment-friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion according to claim 2, It is characterized in that The step of intermittent feeding in step (3) is as follows: add 1 / 7-1 / 5 of the alkaline resin pre-emulsion to the solution of step (2), stir at a constant speed for 3-8 minutes, then add 3 / 40-5 / 40 of the initiator, keep the mixture warm for 20-30 minutes, then add 1 / 5-2 / 5 of the initiator, then dropwise add the remaining alkaline resin pre-emulsion, the dropwise addition time is 100-120 minutes, and after the dropwise addition is completed, keep the mixture warm for 20-40 minutes.

5. The method for preparing the environment-friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion according to claim 2, It is characterized in that The specific steps of step (4) are: adding the shell resin pre-emulsion to the solution of step (3) for 65-75 minutes, and keeping the reaction warm for 1.5-2.5 hours after the addition is completed; then adding a neutralizing agent at a temperature below 40°C and stirring evenly, adjusting the pH to 8.5-9, and obtaining an environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion.

6. The method for preparing the environment-friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion according to claim 5, It is characterized in that The protein is soy protein isolate or β - gelatin; the initiator is a combination of ammonium persulfate or potassium persulfate and n-dodecyl mercaptan, wherein the mass ratio of ammonium persulfate or potassium persulfate to n-dodecyl mercaptan is (8-9):

1.

7. The method for preparing the environment-friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion according to claim 6, It is characterized in that The hard monomer in the core resin pre-emulsion is methyl methacrylate; the hard monomer in the base resin pre-emulsion and the shell resin pre-emulsion consists of methyl methacrylate and styrene, the mass ratio of methyl methacrylate to styrene in the base resin pre-emulsion is (2-2.2):1, and the mass ratio of methyl methacrylate to styrene in the shell resin pre-emulsion is (3-3.2):

1.

8. The method for preparing the environment-friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion according to claim 7, It is characterized in that The soft monomer is lauryl methacrylate; the acrylic epoxy monomer is any one of glycidyl methacrylate or glycidyl acrylate; the acrylic carboxyl monomer is any one of methacrylic acid or acrylic acid; the catalyst is tetrabutylammonium bromide; the pH buffer is one or a combination of sodium bicarbonate or ammonium bicarbonate; and the neutralizer is one or a combination of triethylamine and NN dimethylethanolamine.

9. An environmentally friendly room temperature self-crosslinking three-layer hollow acrylic resin emulsion prepared according to the method according to any one of claims 1 to 8, Features: The latex particles in the three-layer hollow acrylic resin emulsion include a core resin layer, a base resin layer and a shell resin layer from the inside to the outside, and the particle size of the latex particles is 170-200 nm; the mass ratio of the core resin layer, the base resin layer and the shell resin layer is (1.4-1.5): (1.7-2.1): 1.

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