Water-based acrylate emulsion with core-shell structure for overlay as well as preparation method and application of water-based acrylate emulsion

Abstract

The invention discloses a water-based acrylate emulsion with a core-shell structure for a cover surface as well as a preparation method and application of the water-based acrylate emulsion, and belongs to the technical field of building coatings. The emulsion is prepared from the following raw materials in parts by weight: 10 to 30 parts of butyl acrylate, 0 to 10 parts of styrene, 50 to 75 parts of methyl methacrylate, 0.1 to 0.5 part of sodium bicarbonate, 0.5 to 2 parts of hydroxyl monomer, 1 to 3 parts of carboxyl monomer, 0.1 to 0.5 part of initiator, 0.5 to 2 parts of emulsifier, 0.2 to 0.8 part of sulfydryl monomer, 1 to 5 parts of crosslinking monomer, 0.5 to 2 parts of organosilicon monomer, 1 to 2 parts of ammonia water and 130 to 150 parts of deionized water. Wherein the emulsion has a reverse core-shell structure, a core layer is a hard core, a shell layer is a soft shell, the emulsion does not contain a coalescing agent, and the minimum film forming temperature is lower than 20 DEG C. Through a unique reverse core-shell structure design and a formula without a coalescing agent, low film-forming temperature and low semi-volatile organic compound content are realized while excellent stain resistance and water resistance are ensured, strict environmental protection standards are met, and the high-performance building finish-coat paint is suitable for high-performance building finish-coat paint.

Description

Technical Field

[0001] This invention belongs to the field of architectural coatings technology, specifically relating to a core-shell structured waterborne acrylic emulsion for topcoats, its preparation method, and its application. Background Technology

[0002] With increasingly stringent environmental regulations and growing public awareness of environmental protection, water-based coatings are gradually replacing traditional solvent-based coatings and becoming the mainstream in the market. As the outermost protective coating of a building, architectural topcoat needs to possess excellent weather resistance, stain resistance, water resistance, and decorative properties. Architectural topcoat emulsions need to have high hardness to ensure the topcoat meets stain resistance standards, but such polymerized emulsions often have high minimum film-forming temperatures, requiring the addition of large amounts of film-forming aids to lower the minimum film-forming temperature. Currently, most architectural topcoat emulsions on the market lower their minimum film-forming temperature by pre-adding some film-forming aids. However, the upcoming new national standard (GB 30981.1-2025) explicitly limits the semi-volatile organic compounds (SVOCs) in coatings, and the main source of SVOCs in emulsions is film-forming aids. Existing architectural topcoat emulsions cannot meet the requirements of the new standard.

[0003] In addition, existing water-based coatings have some shortcomings in performance under low-temperature conditions, such as decreased flexibility and adhesion, high glass transition temperature, and slow film formation speed at room temperature, making it difficult to meet the needs of rapid construction. These problems seriously restrict the application and promotion of water-based coatings in the field of architectural topcoats.

[0004] Currently, the most effective method is to reduce the amount of semi-volatile organic compounds in the emulsion by using core-shell polymerization technology, with little or no film-forming aids added to the polymerization formulation, in order to meet the requirements of the new standards. However, no waterborne acrylic emulsion has yet been developed that can meet the stringent requirements of architectural topcoats for stain resistance, water whitening resistance, and low water permeability, while also achieving a balance between low film-forming temperature and high hardness. This new type of emulsion not only needs to possess excellent physicochemical properties but also good environmental friendliness and economy to adapt to increasingly stringent environmental regulations and market competition. Summary of the Invention

[0005] To overcome the problems existing in the prior art, the present invention provides an aqueous acrylic emulsion with a core-shell structure for the coating, its preparation method and application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In one aspect, the present invention provides a water-based acrylic emulsion with a core-shell structure for a mask, which is prepared from the following raw materials in parts by weight:

[0008] 10-30 parts butyl acrylate, 0-10 parts styrene, 50-75 parts methyl methacrylate, 0.1-0.5 parts sodium bicarbonate, 0.5-2 parts hydroxyl monomer, 1-3 parts carboxyl monomer, 0.1-0.5 parts initiator, 0.5-2 parts emulsifier, 0.2-0.8 parts mercapto monomer, 1-5 parts crosslinking monomer, 0.5-2 parts organosilicon monomer, 1-2 parts ammonia, and 130-150 parts deionized water;

[0009] The emulsion has a reverse core-shell structure, with a hard core and a soft shell. The emulsion does not contain film-forming aids and has a minimum film-forming temperature of less than 20°C.

[0010] As a further embodiment of the present invention: the hydroxy monomer is at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl acrylate;

[0011] And / or, the carboxyl monomer is at least one of acrylic acid, methacrylic acid, and itaconic acid;

[0012] And / or, the initiator is at least one of ammonium persulfate, sodium persulfate, and potassium persulfate;

[0013] And / or, the emulsifier is at least one of sodium dodecyl sulfate, ammonium lauryl ether sulfate, sodium dodecylbenzene sulfonate, and allyl-containing alkyl alcohol ether sulfate;

[0014] And / or, the thiol monomer is at least one of n-dodecyl mercaptoethanol, mercaptoethanol, and isooctyl mercaptoacrylate;

[0015] And / or, the crosslinking monomer is at least one of glycidyl methacrylate, ethylene glycol dimethacrylate, allyl methacrylate, 2-acryloylamino-2-methylpropanesulfonic acid, diacetone acrylamide, and adipate dihydrazide.

[0016] And / or, the organosilicon monomer is at least one of vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0017] In a second aspect, the present invention provides a method for preparing the above-mentioned core-shell structured aqueous acrylic emulsion, comprising the following steps:

[0018] (1) Mix 30-40% emulsifier, 15-25% deionized water, 70-100% carboxyl monomer, 100% hydroxy monomer, 80-100% butyl acrylate, 15-30% methyl methacrylate, and 0-50% crosslinking monomer, and disperse at high speed to obtain core layer pre-emulsion;

[0019] (2) Add 40-60% deionized water, 20-30% emulsifier, 100% sodium bicarbonate and 5-100% crosslinking monomer to the reactor and heat to 75-85℃;

[0020] (3) Dissolve the initiator in 5-15% deionized water to obtain an initiator solution;

[0021] (4) Add 40-60% initiator solution to the reaction vessel, and simultaneously add the core layer pre-emulsion and 10-20% initiator solution dropwise for 60-90 min, and keep warm for 30 min;

[0022] (5) Mix 30-40% emulsifier, 15-25% deionized water, 0-30% carboxyl monomer, 0-20% butyl acrylate, 100% styrene, 70-85% methyl methacrylate and mercapto monomer, and disperse at high speed to obtain shell pre-emulsion;

[0023] (6) After the reaction vessel is kept warm, add the shell pre-emulsion and 20-40% initiator solution dropwise for 150-180 min.

[0024] (7) When the shell pre-emulsion is added dropwise to the remaining 0-40%, add 0-80% crosslinking monomer or 0-100% organosilicon monomer, and keep warm for 60-90 minutes after the addition is complete;

[0025] (8) Cool down to below 45°C and add ammonia to adjust the pH to 7-9;

[0026] (9) Filter and discharge.

[0027] As a further aspect of the present invention: in step (1), the dispersion time is 30 min;

[0028] And / or, in step (5), the dispersion time is 15 min.

[0029] As a further embodiment of the present invention: after adjusting the pH value in step (8), the method further includes adding 0-100% organosilicon monomer and 0-25% crosslinking monomer and then stirring.

[0030] In a third aspect, the present invention provides the application of the above-described waterborne acrylic emulsion with a core-shell structure for topcoat, or the waterborne acrylic emulsion with a core-shell structure for topcoat prepared by the above-described method for topcoat, in architectural topcoat paints.

[0031] The beneficial effects of this invention are as follows:

[0032] (1) This invention designs an aqueous acrylic emulsion with a reverse core-shell structure. During polymerization, the strong hydrophobicity of the hard-shell monomer (styrene / methyl methacrylate) and the strong hydrophilicity of the soft-core monomer are used to drive the hydrophobic monomer to migrate into the particle under thermodynamic conditions, thus forming a unique core-shell structure. This structure achieves an optimized combination of performance: the high glass transition temperature (Tg) of the hard core endows the coating with excellent rigidity, stain resistance, and water-blocking properties; the low Tg soft shell of the exterior ensures that the emulsion has good film-forming properties and film continuity at low temperatures. Compared with the traditional "hard core-soft shell" structure, the reverse design makes the hard phase the main load-bearer, while the soft phase mainly plays a bonding role, achieving a "combination of rigidity and flexibility". At the same time, by introducing organosilicon monomers and crosslinking monomers, the network integrity of the coating is further enhanced, significantly improving its water resistance and stain resistance.

[0033] (2) This invention employs a film-forming agent-free formulation design. By precisely controlling the monomer composition and segmented polymerization process, it achieves a minimum film-forming temperature below 20°C while effectively controlling the content of semi-volatile organic compounds (SVOCs) in the emulsion, thus meeting the requirements of the latest environmental protection standards such as GB 30981.1-2025. This emulsion can form a film rapidly at room temperature, which not only meets the needs of rapid construction but also overcomes the technical bottleneck of slow film-forming speed and poor film-forming properties of traditional water-based coatings at low temperatures.

[0034] (3) Through the synergistic effect of the above-mentioned structural design and preparation process, this invention significantly improves the flexibility and adhesion of the coating under low-temperature conditions while maintaining high hardness and excellent stain resistance, thus solving the problem of performance degradation that easily occurs in existing water-based topcoats in low-temperature environments. This technology achieves a good balance between low film-forming temperature and high hardness, and combines excellent environmental friendliness, construction adaptability, and comprehensive coating performance, providing an effective way to develop a new generation of high-performance environmentally friendly architectural topcoats. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples, but these should not be construed as limiting the present patent. Unless otherwise specified, the experimental methods or testing methods described in the following embodiments are conventional methods; the reagents and materials, unless otherwise specified, are obtained from conventional commercial sources or prepared using conventional methods.

[0036] Example 1

[0037] A core-shell structured waterborne acrylic emulsion for a mask comprises the following raw materials: 27 parts butyl acrylate, 8 parts styrene, 65 parts methyl methacrylate, 0.2 parts sodium bicarbonate, 1 part hydroxyethyl acrylate, 2.5 parts methacrylic acid, 0.36 parts ammonium persulfate, 1.8 parts sodium dodecylbenzenesulfonate, 0.4 parts n-dodecyl mercaptan, 1 part 2-acrylamido-2-methylpropanesulfonic acid, 1.2 parts vinyltrimethoxysilane, 1.2 parts ammonia, and 141 parts deionized water.

[0038] A method for preparing an aqueous acrylic emulsion with a core-shell structure for a mask surface includes the following steps:

[0039] (1) Place 0.7 parts sodium dodecylbenzenesulfonate, 22 parts deionized water, 2 parts methacrylic acid, 1 part hydroxyethyl acrylate, 27 parts butyl acrylate, and 16.8 parts methyl methacrylate in an emulsification tank and disperse at high speed for 30 minutes to prepare as the first stage core layer pre-emulsion.

[0040] (2) Place 83 parts of deionized water, 0.4 parts of sodium dodecylbenzenesulfonate, 0.2 parts of sodium bicarbonate, and 1 part of 2-acrylamido-2-methylpropanesulfonic acid in a reaction vessel equipped with a thermometer, condenser and stirrer, and stir to raise the temperature to 80°C.

[0041] (3) Dissolve 0.36 parts of ammonium persulfate in 12 parts of deionized water by stirring, and use it as an initiator solution for later use;

[0042] (4) When the temperature of the reactor is stable at 80℃, take out 7 portions of the initiator solution prepared in step (3) and add them to the reactor. Then start to add the first stage pre-emulsion prepared in step (1) and 1.8 portions of the initiator solution prepared in step (3). The adding time is controlled at 80 min. After adding, keep warm for 30 min. The keeping temperature is 80℃.

[0043] (5) Place 0.7 parts sodium dodecylbenzenesulfonate, 24 parts deionized water, 0.5 parts methacrylic acid, 8 parts styrene, 48.2 parts methyl methacrylate and 0.4 parts n-dodecyl mercaptan in an emulsification tank and disperse at high speed for 15 minutes to prepare as the second stage shell pre-emulsion.

[0044] (6) After the reaction vessel is kept warm, start adding the second-stage pre-emulsion prepared in step (5) and the remaining 3.56 parts of initiator solution in step (3), and control the adding time to 180 min;

[0045] (7) When the pre-emulsion added in step (6) is 30% remaining, add 1.2 parts of vinyltrimethoxysilane into the emulsion tank and drop it into the reaction vessel. After the addition is complete, keep the temperature at 80°C for 90 minutes.

[0046] (8) After the heat preservation in step (7) is completed, cool down to 45°C and add 1.2 parts of ammonia water to adjust the pH value;

[0047] (9) Filter the material to obtain the water-based acrylic emulsion for the core-shell structure cover.

[0048] Example 2

[0049] A core-shell structured waterborne acrylic emulsion for a mask comprises the following raw materials: 28 parts butyl acrylate, 10 parts styrene, 62 parts methyl methacrylate, 0.2 parts sodium bicarbonate, 0.8 parts hydroxyethyl methacrylate, 2.2 parts methacrylic acid, 0.38 parts ammonium persulfate, 1.8 parts lauryl ether ammonium sulfate, 0.3 parts isooctyl mercaptoacrylate, 0.4 parts 2-acrylamido-2-methylpropanesulfonic acid, 1.6 parts glycidyl methacrylate, 1.1 parts ammonia, 0.5 parts γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 141 parts deionized water.

[0050] A method for preparing an aqueous acrylic emulsion with a core-shell structure for a mask surface includes the following steps:

[0051] (1) Place 0.7 parts of ammonium lauryl ether sulfate, 22 parts of deionized water, 2.2 parts of methacrylic acid, 0.8 parts of hydroxyethyl methacrylate, 28 parts of butyl acrylate and 16 parts of methyl methacrylate in an emulsification tank and disperse at high speed for 30 minutes to prepare as the first stage core layer pre-emulsion.

[0052] (2) Place 83 parts of deionized water, 0.4 parts of lauryl ether ammonium sulfate, 0.2 parts of sodium bicarbonate and 0.4 parts of 2-acrylamido-2-methylpropanesulfonic acid in a reaction vessel equipped with a thermometer, condenser and stirrer, and stir to raise the temperature to 80°C.

[0053] (3) Dissolve 0.38 parts of ammonium persulfate in 12 parts of deionized water and use it as an initiator solution.

[0054] (4) When the temperature of the reactor is stable at 80℃, take out 7 portions of the initiator solution prepared in step (3) and add them to the reactor. Then start to add the first stage pre-emulsion prepared in step (1) and 1.8 portions of the initiator solution prepared in step (3). The adding time is controlled at 80 min. After adding, keep warm for 30 min. The keeping temperature is 80℃.

[0055] (5) Place 0.7 parts of ammonium lauryl ether sulfate, 24 parts of deionized water, 10 parts of styrene, 46 parts of methyl methacrylate and 0.3 parts of isooctyl mercaptoacrylate in an emulsification tank and disperse at high speed for 15 minutes to prepare as the second stage shell pre-emulsion.

[0056] (6) After the reaction vessel is kept warm, start adding the second-stage pre-emulsion prepared in step (5) and the remaining 3.56 parts of initiator solution in step (3), and control the adding time to 180 min;

[0057] (7) After the pre-emulsion added in step (6) is finished, add 1.6 parts of glycidyl methacrylate into the emulsion tank and drop it into the reaction vessel. After the addition is finished, keep it warm for 90 minutes at a temperature of 80°C.

[0058] (8) After the heat preservation in step (7) is completed, cool down to 45°C and add 1.1 parts of ammonia water to adjust the pH value;

[0059] (9) Add 0.5 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and stir for 15 min. Filter the mixture to obtain the water-based acrylic emulsion for the core-shell structure cover.

[0060] Example 3

[0061] A core-shell structured waterborne acrylic emulsion for a mask comprises the following raw materials: 28 parts butyl acrylate, 8 parts styrene, 64 parts methyl methacrylate, 0.2 parts sodium bicarbonate, 0.8 parts hydroxyethyl acrylate, 2.4 parts methacrylic acid, 0.28 parts ammonium persulfate, 1.8 parts lauryl ether ammonium sulfate, 0.5 parts isooctyl mercaptoacrylate, 0.4 parts 2-acrylamido-2-methylpropanesulfonic acid, 1.6 parts glycidyl methacrylate, 1.2 parts ammonia, 0.5 parts γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 141 parts deionized water.

[0062] A method for preparing an aqueous acrylic emulsion with a core-shell structure for a mask surface includes the following steps:

[0063] (1) Place 0.7 parts of ammonium lauryl ether sulfate, 22 parts of deionized water, 2.4 parts of methacrylic acid, 0.8 parts of hydroxyethyl acrylate, 28 parts of butyl acrylate, and 16 parts of methyl methacrylate in an emulsification tank and disperse at high speed for 30 minutes to prepare as the first stage core layer pre-emulsion.

[0064] (2) Place 83 parts of deionized water, 0.4 parts of lauryl ether ammonium sulfate, 0.2 parts of sodium bicarbonate and 0.4 parts of 2-acrylamido-2-methylpropanesulfonic acid in a reaction vessel equipped with a thermometer, condenser and stirrer, and stir to raise the temperature to 82°C.

[0065] (3) Dissolve 0.28 parts of ammonium persulfate in 12 parts of deionized water by stirring, and use it as an initiator solution for later use;

[0066] (4) When the temperature of the reactor is stable at 82℃, take out 7 portions of the initiator solution prepared in step (3) and add them to the reactor. Then start to add the first stage pre-emulsion prepared in step (1) and 1.8 portions of the initiator solution prepared in step (3). The adding time is controlled at 80 min. After adding, keep warm for 30 min. The keeping temperature is 82℃.

[0067] (5) Place 0.7 parts of ammonium lauryl ether sulfate, 24 parts of deionized water, 8 parts of styrene, 48 parts of methyl methacrylate and 0.5 parts of isooctyl mercaptoacrylate in an emulsification tank and disperse at high speed for 15 minutes to prepare as the second stage shell pre-emulsion.

[0068] (6) After the reaction vessel is kept warm, start adding the second-stage pre-emulsion prepared in step (5) and the remaining 3.56 parts of initiator solution in step (3), and control the adding time to 180 min;

[0069] (7) After the pre-emulsion added in step (6) is finished, add 1.6 parts of glycidyl methacrylate into the emulsion tank and drop it into the reaction vessel. After the addition is finished, keep it warm for 90 minutes at a temperature of 82°C.

[0070] (8) After the heat preservation in step (7) is completed, cool down to 45°C and add 1.2 parts of ammonia water to adjust the pH value;

[0071] (9) Add 0.5 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and stir for 15 min. Filter the mixture to obtain the water-based acrylic emulsion for the core-shell structure cover.

[0072] Example 4

[0073] A core-shell structured waterborne acrylic emulsion for a mask comprises the following raw materials: 28 parts butyl acrylate, 8 parts styrene, 64 parts methyl methacrylate, 0.2 parts sodium bicarbonate, 0.8 parts hydroxyethyl acrylate, 2.2 parts acrylic acid, 0.28 parts potassium persulfate, 1.8 parts sodium dodecylbenzenesulfonate, 0.4 parts n-dodecyl mercaptan, 0.4 parts 2-acrylamido-2-methylpropanesulfonic acid, 1 part glycidyl methacrylate, 2 parts diacetone acrylamide, 1 part adipic acid dihydrazide, 1.7 parts ammonia, 0.5 parts γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 141 parts deionized water.

[0074] A method for preparing an aqueous acrylic emulsion with a core-shell structure for a mask surface includes the following steps:

[0075] (1) Place 0.7 parts sodium dodecylbenzenesulfonate, 22 parts deionized water, 2.2 parts acrylic acid, 0.8 parts hydroxyethyl acrylate, 28 parts butyl acrylate, 16 parts methyl methacrylate, and 2 parts diacetone acrylamide in an emulsification tank and disperse at high speed for 30 minutes to prepare as the first stage core layer pre-emulsion.

[0076] (2) Place 83 parts of deionized water, 0.4 parts of sodium dodecylbenzenesulfonate, 0.2 parts of sodium bicarbonate and 0.4 parts of 2-acrylamido-2-methylpropanesulfonic acid in a reaction vessel equipped with a thermometer, condenser and stirrer, and stir to raise the temperature to 82°C.

[0077] (3) Dissolve 0.28 parts of potassium persulfate in 12 parts of deionized water by stirring, and use it as an initiator solution for later use;

[0078] (4) When the temperature of the reactor is stable at 82℃, take out 7 portions of the initiator solution prepared in step (3) and add them to the reactor. Then start to add the first stage pre-emulsion prepared in step (1) and 1.8 portions of the initiator solution prepared in step (3). The adding time is controlled at 80 min. After adding, keep warm for 30 min. The keeping temperature is 82℃.

[0079] (5) Place 0.7 parts sodium dodecylbenzenesulfonate, 24 parts deionized water, 8 parts styrene, 48 parts methyl methacrylate and 0.4 parts n-dodecyl mercaptan in an emulsification tank and disperse at high speed for 15 minutes to prepare as the second stage shell pre-emulsion.

[0080] (6) After the reaction vessel is kept warm, start adding the second-stage pre-emulsion prepared in step (5) and the remaining 3.56 parts of initiator solution in step (3), and control the adding time to 180 min;

[0081] (7) After the pre-emulsion added in step (6) is finished, add 1 part of glycidyl methacrylate into the emulsion tank and drop it into the reaction vessel. After the addition is finished, keep it warm for 90 minutes at a temperature of 82°C.

[0082] (8) After the heat preservation in step (7) is completed, cool down to 45°C, add 1.7 parts of ammonia water to adjust the pH value, add 1 part of adipic acid dihydrazide and stir for 15 minutes;

[0083] (9) Add 0.5 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and stir for 15 min. Filter the mixture to obtain the water-based acrylic emulsion for the core-shell structure cover.

[0084] Example 5

[0085] A core-shell structured waterborne acrylic emulsion for a mask comprises the following raw materials: 28 parts butyl acrylate, 8 parts styrene, 64 parts methyl methacrylate, 0.2 parts sodium bicarbonate, 0.8 parts hydroxyethyl methacrylate, 2.4 parts methacrylic acid, 0.28 parts potassium persulfate, 1.8 parts allyl alkyl alcohol ether sulfate, 0.5 parts isooctyl mercaptoacrylate, 0.4 parts 2-acrylamido-2-methylpropanesulfonic acid, 1.5 parts glycidyl methacrylate, 1.2 parts ammonia, 0.5 parts γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 141 parts deionized water.

[0086] A method for preparing an aqueous acrylic emulsion with a core-shell structure for a mask surface includes the following steps:

[0087] (1) Place 0.7 parts of allyl alkyl alcohol ether sulfate, 22 parts of deionized water, 2.4 parts of methacrylic acid, 0.8 parts of hydroxyethyl methacrylate, 28 parts of butyl acrylate and 16 parts of methyl methacrylate in an emulsification tank and disperse at high speed for 30 min to prepare as the first stage core layer pre-emulsion.

[0088] (2) Place 83 parts of deionized water, 0.4 parts of allyl alkyl alcohol ether sulfate, 0.2 parts of sodium bicarbonate, and 0.4 parts of 2-acrylamido-2-methylpropanesulfonic acid in a reaction vessel equipped with a thermometer, condenser and stirrer, and stir to raise the temperature to 82°C.

[0089] (3) Dissolve 0.28 parts of potassium persulfate in 12 parts of deionized water by stirring, and use it as an initiator solution for later use;

[0090] (4) When the temperature of the reactor is stable at 82℃, take out 7 portions of the initiator solution prepared in step (3) and add them to the reactor. Then start to add the first stage pre-emulsion prepared in step (1) and 1.8 portions of the initiator solution prepared in step (3). The adding time is controlled at 80 min. After adding, keep warm for 30 min. The keeping temperature is 82℃.

[0091] (5) Place 0.7 parts of allyl alkyl alcohol ether sulfate, 24 parts of deionized water, 8 parts of styrene, 48 parts of methyl methacrylate and 0.5 parts of isooctyl mercaptoacrylate in an emulsification tank and disperse at high speed for 15 min to prepare as the second stage shell pre-emulsion.

[0092] (6) After the reaction vessel is kept warm, start adding the second-stage pre-emulsion prepared in step (5) and the remaining 3.56 parts of initiator solution in step (3), and control the adding time to 180 min;

[0093] (7) After the pre-emulsion added in step (6) is finished, add 1.5 parts of glycidyl methacrylate into the emulsion tank and drop it into the reaction vessel. After the addition is finished, keep it warm for 90 minutes at a temperature of 82°C.

[0094] (8) After the heat preservation in step (7) is completed, cool down to 45°C and add 1.2 parts of ammonia water to adjust the pH value;

[0095] (9) Add 0.5 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and stir for 15 min. Filter the mixture to obtain the water-based acrylic emulsion for the core-shell structure cover.

[0096] Example 6

[0097] A core-shell structured waterborne acrylic emulsion for a mask comprises the following raw materials: 28 parts butyl acrylate, 10 parts styrene, 62 parts methyl methacrylate, 0.2 parts sodium bicarbonate, 0.8 parts hydroxyethyl acrylate, 2.4 parts methacrylic acid, 0.28 parts ammonium persulfate, 1.8 parts ammonium lauryl ether sulfate, 0.5 parts isooctyl mercaptoacrylate, 0.4 parts 2-acrylamido-2-methylpropanesulfonic acid, 1.5 parts glycidyl methacrylate, 1.1 parts ammonia, 0.5 parts γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 141 parts deionized water.

[0098] A method for preparing an aqueous acrylic emulsion with a core-shell structure for a mask surface includes the following steps:

[0099] (1) Place 0.7 parts of ammonium lauryl ether sulfate, 22 parts of deionized water, 2.2 parts of methacrylic acid, 0.8 parts of hydroxyethyl acrylate, 26 parts of butyl acrylate, and 15 parts of methyl methacrylate in an emulsification tank and disperse at high speed for 30 minutes to prepare as the first stage core layer pre-emulsion.

[0100] (2) Place 83 parts of deionized water, 0.4 parts of lauryl ether ammonium sulfate, 0.2 parts of sodium bicarbonate and 0.4 parts of 2-acrylamido-2-methylpropanesulfonic acid in a reaction vessel equipped with a thermometer, condenser and stirrer, and stir to raise the temperature to 82°C.

[0101] (3) Dissolve 0.28 parts of potassium persulfate in 12 parts of deionized water by stirring, and use it as an initiator solution for later use;

[0102] (4) When the temperature of the reactor is stable at 82℃, take out 7 portions of the initiator solution prepared in step (3) and add them to the reactor. Then start to add the first stage pre-emulsion prepared in step (1) and 1.8 portions of the initiator solution prepared in step (3). The adding time is controlled at 80 min. After adding, keep warm for 30 min. The keeping temperature is 82℃.

[0103] (5) Place 0.7 parts of ammonium lauryl ether sulfate, 24 parts of deionized water, 0.2 parts of methacrylic acid, 2 parts of butyl acrylate, 10 parts of styrene, 47 parts of methyl methacrylate and 0.5 parts of isooctyl mercaptoacrylate in an emulsification tank and disperse at high speed for 15 minutes to prepare as the second stage shell pre-emulsion.

[0104] (6) After the reaction vessel is kept warm, start adding the second-stage pre-emulsion prepared in step (5) and the remaining 3.56 parts of initiator solution in step (3), and control the adding time to 180 min;

[0105] (7) After the pre-emulsion added in step (6) is finished, add 1.5 parts of glycidyl methacrylate into the emulsion tank and drop it into the reaction vessel. After the addition is finished, keep it warm for 90 minutes at a temperature of 82°C.

[0106] (8) After the heat preservation in step (7) is completed, cool down to 45°C and add 1.1 parts of ammonia water to adjust the pH value;

[0107] (9) Add 0.5 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and stir for 15 min. Filter the mixture to obtain the water-based acrylic emulsion for the core-shell structure cover.

[0108] Example 7

[0109] A core-shell structured waterborne acrylic emulsion for a mask comprises the following raw materials: 28 parts butyl acrylate, 72 parts methyl methacrylate, 0.2 parts sodium bicarbonate, 0.8 parts hydroxyethyl acrylate, 2.4 parts acrylic acid, 0.28 parts potassium persulfate, 1.8 parts ammonium lauryl ether sulfate, 0.5 parts isooctyl mercaptoacrylate, 0.4 parts 2-acrylamido-2-methylpropanesulfonic acid, 1.6 parts glycidyl methacrylate, 1.9 parts ammonia, 0.6 parts γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 141 parts deionized water.

[0110] A method for preparing an aqueous acrylic emulsion with a core-shell structure for a mask surface includes the following steps:

[0111] (1) Place 0.7 parts sodium dodecyl sulfate, 22 parts deionized water, 2.4 parts acrylic acid, 0.8 parts hydroxyethyl acrylate, 28 parts butyl acrylate, and 16 parts methyl methacrylate in an emulsification tank and disperse at high speed for 30 minutes to prepare as the first stage core layer pre-emulsion.

[0112] (2) Place 83 parts of deionized water, 0.4 parts of lauryl ether ammonium sulfate, 0.2 parts of sodium bicarbonate and 0.4 parts of 2-acrylamido-2-methylpropanesulfonic acid in a reaction vessel equipped with a thermometer, condenser and stirrer, and stir to raise the temperature to 82°C.

[0113] (3) Dissolve 0.28 parts of ammonium persulfate in 12 parts of deionized water by stirring, and use it as an initiator solution for later use;

[0114] (4) When the temperature of the reactor is stable at 82℃, take out 7 portions of the initiator solution prepared in step (3) and add them to the reactor. Then start to add the first stage pre-emulsion prepared in step (1) and 1.8 portions of the initiator solution prepared in step (3). The adding time is controlled at 80 min. After adding, keep warm for 30 min. The keeping temperature is 82℃.

[0115] (5) Place 0.7 parts of ammonium lauryl ether sulfate, 24 parts of deionized water, 56 parts of methyl methacrylate and 0.5 parts of isooctyl mercaptoacrylate in an emulsification tank and disperse at high speed for 15 minutes to prepare as the second stage shell pre-emulsion.

[0116] (6) After the reaction vessel is kept warm, start adding the second-stage pre-emulsion prepared in step (5) and the remaining 3.56 parts of initiator solution in step (3), and control the adding time to 180 min;

[0117] (7) After the pre-emulsion added in step (6) is finished, add 1.6 parts of glycidyl methacrylate into the emulsion tank and drop it into the reaction vessel. After the addition is finished, keep it warm for 90 minutes at a temperature of 82°C.

[0118] (8) After the heat preservation in step (7) is completed, cool down to 45°C and add 1.9 parts of ammonia water to adjust the pH value;

[0119] (9) Add 0.6 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and stir for 15 min. Filter the mixture to obtain the water-based acrylic emulsion for the core-shell structure cover.

[0120] The present invention also provides the following comparative examples.

[0121] Comparative Example 1

[0122] The only difference from Example 3 is that:

[0123] 1. Step (1) Place 0.7 parts of ammonium lauryl ether sulfate, 24 parts of deionized water, 8 parts of styrene, 48 parts of methyl methacrylate and 0.5 parts of isooctyl mercaptoacrylate in an emulsification tank and disperse at high speed for 30 minutes to prepare as the first stage core layer pre-emulsion.

[0124] 2. In step (5), 0.7 parts of ammonium lauryl ether sulfate, 22 parts of deionized water, 2.4 parts of methacrylic acid, 0.8 parts of hydroxyethyl acrylate, 28 parts of butyl acrylate, and 16 parts of methyl methacrylate are placed in an emulsification tank and dispersed at high speed for 15 minutes to prepare as the second-stage shell pre-emulsion.

[0125] Comparative Example 2

[0126] The only difference from Example 1 is that:

[0127] 1. Step (1) Place 0.7 parts sodium dodecylbenzenesulfonate, 24 parts deionized water, 0.5 parts methacrylic acid, 8 parts styrene, 48.2 parts methyl methacrylate, and 0.4 parts n-dodecyl mercaptan in an emulsification tank and disperse at high speed for 30 minutes to prepare as the first stage core layer pre-emulsion.

[0128] 2. Step (5): 0.7 parts sodium dodecylbenzenesulfonate, 22 parts deionized water, 2 parts methacrylic acid, 1 part hydroxyethyl acrylate, 27 parts butyl acrylate, and 16.8 parts methyl methacrylate are placed in an emulsification tank and dispersed at high speed for 15 minutes to prepare as the second-stage shell pre-emulsion.

[0129] Comparative Example 3

[0130] The only difference from Example 5 is:

[0131] 1. Step (1) Place 0.7 parts of allyl alkyl alcohol ether sulfate, 24 parts of deionized water, 8 parts of styrene, 48 parts of methyl methacrylate and 0.5 parts of isooctyl mercaptoacrylate in an emulsification tank and disperse at high speed for 30 minutes to prepare as the first stage core layer pre-emulsion.

[0132] 2. Step (5): Place 0.7 parts of allyl alkyl alcohol ether sulfate, 22 parts of deionized water, 2.4 parts of methacrylic acid, 0.8 parts of hydroxyethyl methacrylate, 28 parts of butyl acrylate, and 16 parts of methyl methacrylate in an emulsification tank and disperse at high speed for 15 minutes to prepare as the second stage shell pre-emulsion.

[0133] Comparative Example 4

[0134] The difference from Example 1 is that 1.2 parts of vinyltrimethoxysilane in step (7) are directly added to the first stage core layer pre-emulsion in step (1).

[0135] Comparative Example 5

[0136] The difference from Example 3 is only that 1.6 parts of glycidyl methacrylate in step (7) are directly added to the shell pre-emulsion in the second stage of step (5).

[0137] Comparative Example 6

[0138] The difference from Example 3 is only that steps (1) and (5) are combined with the emulsifying monomer using the same monomer and conventional polymerization process (non-core-shell polymerization).

[0139] Specifically, the raw materials include: 28 parts butyl acrylate, 8 parts styrene, 64 parts methyl methacrylate, 0.2 parts sodium bicarbonate, 0.8 parts hydroxyethyl acrylate, 2.4 parts methacrylic acid, 0.28 parts ammonium persulfate, 1.8 parts ammonium lauryl ether sulfate, 0.5 parts isooctyl mercaptoacrylate, 0.4 parts 2-acrylamido-2-methylpropanesulfonic acid, 1.6 parts glycidyl methacrylate, 1.2 parts ammonia, 0.5 parts γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 141 parts deionized water.

[0140] The preparation method includes the following steps:

[0141] (1) Place 1.4 parts of ammonium lauryl ether sulfate, 46 parts of deionized water, 2.4 parts of methacrylic acid, 0.8 parts of hydroxyethyl acrylate, 28 parts of butyl acrylate, 64 parts of methyl methacrylate, 8 parts of styrene, and 0.5 parts of isooctyl mercaptoacrylate in an emulsification tank and disperse at high speed for 30 minutes to prepare a pre-emulsion for later use.

[0142] (2) Place 83 parts of deionized water, 0.4 parts of lauryl ether ammonium sulfate, 0.2 parts of sodium bicarbonate and 0.4 parts of 2-acrylamido-2-methylpropanesulfonic acid in a reaction vessel equipped with a thermometer, condenser and stirrer, and stir to raise the temperature to 82°C.

[0143] (3) Dissolve 0.28 parts of ammonium persulfate in 12 parts of deionized water by stirring, and use it as an initiator solution for later use;

[0144] (4) When the temperature of the reactor is stable at 82℃, take out 7 portions of the initiator solution prepared in step (3) and add them to the reactor. Then start to add the pre-emulsion prepared in step (1) and the remaining initiator solution prepared in step (3). The addition time is controlled to be completed in 210 minutes, and the reaction temperature is 82℃.

[0145] (5) After the pre-emulsion added in step (4) is finished, add 1.6 parts of glycidyl methacrylate into the emulsion tank and drop it into the reaction vessel. After the addition is finished, keep it warm for 60 minutes at a temperature of 82°C.

[0146] (6) After the heat preservation in step (5) is completed, cool down to 45°C and add 1.2 parts of ammonia water to adjust the pH value;

[0147] (7) Add 0.5 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and stir for 15 min, then filter and discharge.

[0148] Comparative Example 7

[0149] Shanghai Baolijia Company produces the traditional face mask emulsion BLJ-9306.

[0150] Example 1

[0151] The emulsions of Examples 1-7 and Comparative Examples 1-7 were tested using the following methods:

[0152] I. Solid content: Tested according to the test method for non-volatile substances in GB / T 20623-2006 standard for emulsions for architectural coatings.

[0153] II. pH value: The pH value was tested according to the test method in GB / T 20623-2006 Standard for Emulsions for Architectural Coatings.

[0154] III. Particle size: Tested using a Malvern laser particle size analyzer.

[0155] IV. MFFT: Performed in accordance with GB / T9267-2008.

[0156] The properties of the emulsions prepared in Examples 1-7 and Comparative Examples 1-7 were measured, and the results are shown in Table 1.

[0157] Table 1

[0158]

[0159]

[0160] Example 2

[0161] The emulsions obtained in Examples 1-7 and Comparative Examples 1-7 were used to prepare water-based topcoat varnishes for testing. The varnish formulations are shown in Table 2 below:

[0162] Table 2. Water-based Topcoat Varnish Formulation

[0163] raw material mass percentage / % lotion 50 Film-forming aids 2.5～5 antifreeze 0.4 Thickener 0.5 bactericide 0.1 water Supplement the remaining amount

[0164] Test method: The test shall be conducted in accordance with GB / T 9780-2013 Test Method for Stain Resistance of Architectural Coatings, with two rapid cycles in an oven (the lower the rate of decrease in reflectance, the better the stain resistance).

[0165] Water resistance and water whitening resistance: Spray a layer of multicolor paint on a 150mm×70mm×(4~6)mm asbestos-free cement board (Biaogeda). After the surface is dry, cure it in a 50℃ oven for 3 days. Then brush on the above topcoat. After the surface is dry, cure it in a 50℃ oven for 24 hours. Then immerse it in water for 24 hours and observe its bubbling and discoloration.

[0166] Low-temperature film-forming properties: A film was formed on a glass plate using a 150-micron wire rod. The plate was then placed in a 5°C low-temperature and humidity chamber to dry and observe whether the paint film had formed.

[0167] The SVOC content test of water-based topcoat is conducted in accordance with the requirements of GB 30981.1-2025, which stipulates that the SVOC of water-based clear topcoat should be ≤180g / L.

[0168] The test results are shown in Table 3:

[0169] Table 3 Test Results of Water-Based Topcoat Varnish

[0170]

[0171] As shown in Table 3, among Examples 1-4, the emulsion in Example 3 achieved the best overall performance in terms of key indicators such as water resistance, stain resistance, and SVOC content. This invention, through a special formulation design, employs a combination of a hydrophobic hard shell and a hydrophilic soft core, resulting in a reverse encapsulation phenomenon in the formation of core-shell latex particles. Compared to the typical hard-core, soft-shell forward encapsulation structure, this exhibits significant advantages in terms of minimum film-forming temperature, stain resistance, and water resistance, achieving the goals of low film-forming temperature, low SVOC, and high performance for the topcoat emulsion.

[0172] Finally, it should be noted that in this invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0173] Although this disclosure has been described above through specific embodiments, it should be understood that those skilled in the art can devise various modifications, improvements, or equivalents to this disclosure within the spirit and scope of the appended solutions. Such modifications, improvements, or equivalents should also be considered to be included within the scope of protection claimed in this disclosure.

Claims

1. A water-based acrylate emulsion for overcoating having a core-shell structure, characterized by, Prepared from the following raw materials by weight: Butyl acrylate 10-30 parts, styrene 0-10 parts, methyl methacrylate 50-75 parts, sodium bicarbonate 0.1-0.5 parts, hydroxyl monomer 0.5-2 parts, carboxyl monomer 1-3 parts, initiator 0.1-0.5 parts, emulsifier 0.5-2 parts, mercapto monomer 0.2-0.8 parts, crosslinking monomer 1-5 parts, silicone monomer 0.5-2 parts, ammonia 1-2 parts, deionized water 130-150 parts; The emulsion has a reverse core-shell structure, the core layer is a hard core, the shell layer is a soft shell, and the emulsion does not contain a film-forming aid, and the minimum film-forming temperature is lower than 20℃.

2. The water-based acrylate emulsion for overcoating having a core-shell structure according to claim 1, characterized by, The hydroxyl monomer is at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl acrylate; And / or, the carboxyl monomer is at least one of acrylic acid, methacrylic acid, and itaconic acid; And / or, the initiator is at least one of ammonium persulfate, sodium persulfate, and potassium persulfate; And / or, the emulsifier is at least one of sodium dodecyl sulfate, ammonium lauryl ether sulfate, sodium dodecylbenzenesulfonate, and allyl-containing alkyl alcohol ether sulfate; And / or, the mercapto monomer is at least one of n-dodecanethiol, mercaptoethanol, and mercaptoisooctyl acrylate; And / or, the crosslinking monomer is at least one of glycidyl methacrylate, ethylene glycol dimethacrylate, allyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid, diacetone acrylamide, and adipic acid dihydrazide; And / or, the silicone monomer is at least one of vinyltrimethoxysilane, methacryloyloxypropyltrimethoxysilane, and gamma-(2,3-epoxypropoxy)propyltrimethoxysilane.

3. The method for preparing a water-based acrylate emulsion for overcoating having a core-shell structure according to claim 1 or 2, characterized in that, The method comprises the following steps: (1) Mix 30-40% emulsifier, 15-25% deionized water, 70-100% carboxyl monomer, 100% hydroxyl monomer, 80-100% butyl acrylate, 15-30% methyl methacrylate, and 0-50% crosslinking monomer, and high-speed disperse to obtain a core layer pre-emulsion; (2) Add 40-60% deionized water, 20-30% emulsifier, 100% sodium bicarbonate, and 5-100% crosslinking monomer to a reaction kettle, and heat to 75-85℃; (3) Dissolve the initiator in 5-15% deionized water to obtain an initiator solution; (4) Add 40-60% initiator solution to the reaction kettle, and drop the core layer pre-emulsion and 10-20% initiator solution at the same time, drop for 60-90 min, and keep warm for 30 min; (5) Mix 30-40% emulsifier, 15-25% deionized water, 0-30% carboxyl monomer, 0-20% butyl acrylate, 100% styrene, 70-85% methyl methacrylate, and mercapto monomer, and high-speed disperse to obtain a shell layer pre-emulsion; (6) After the reaction kettle is kept warm, drop the shell layer pre-emulsion and 20-40% initiator solution, and drop for 150-180 min; (7) When the shell pre-emulsified droplets are added to the remaining 0-40%, 0-80% cross-linking monomers or 0-100% silicone monomers are added, and after the addition is completed, the temperature is maintained for 60-90 min; (8) The temperature is lowered to below 45°C, and ammonia is added to adjust the pH to 7-9; (9) The filtrate is discharged.

4. The method for preparing a water-based acrylate emulsion for overcoating having a core-shell structure according to claim 3, characterized by, In step (1), the dispersion time is 30 min. And / or, in step (5), the dispersion time is 15 min.

5. The method for preparing a water-based acrylate emulsion for overcoating having a core-shell structure according to claim 3, characterized by, After adjusting the pH value in step (8), the operation of adding 0-100% silicone monomers and 0-25% cross-linking monomers and stirring is further included.

6. The use of the water-based acrylic emulsion with a core-shell structure according to claims 1-2 or the water-based acrylic emulsion with a core-shell structure prepared by the preparation method of the water-based acrylic emulsion with a core-shell structure according to claims 3-5 in architectural finish paint.

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