Polymer emulsion, preparation method therefor, and use method thereof in preparation of high-build polymer cement coating

Abstract

Disclosed in the present invention are a polymer emulsion, a preparation method therefor, and a use method thereof in the preparation of a high-build polymer cement coating. The polymer emulsion is prepared from the following raw materials: monomers, an emulsifier, an initiator and an auxiliary agent, wherein the monomers comprise styrene, butyl acrylate, isooctyl acrylate and a functional monomer, the functional monomer comprising acrylamide, methacrylic acid and 2-carboxyethyl acrylate, and the auxiliary agent comprises a retarder and a dispersant. For thick coating films formed by high-build polymer cement coatings prepared from the polymer emulsion of the present invention, the cracking problem during high-build coating of coatings is overcome, and a good open time is achieved.

Description

A polymer emulsion, its preparation method, and its application in the preparation of thick-film polymer cementitious coatings.

[0001] This application claims priority to Chinese patent application 2025100905882, filed on January 21, 2025. The entire contents of the aforementioned Chinese patent application are incorporated herein by reference. Technical Field

[0002] This invention belongs to the field of cement coating technology, specifically relating to a polymer emulsion, its preparation method, and its application in the preparation of thick-film polymer cement coatings. Background Technology

[0003] Polymer cement coatings are mainly composed of cement and other powders. They are mixed with liquid components and applied using a thin-coat, multi-brush technique. Applying a thick layer at once can easily cause cracking. Therefore, multiple applications are required to achieve a certain thickness, significantly increasing construction costs. The open time of polymer cement coatings refers to the time interval from coating preparation to the point where the coating maintains stable application and mechanical properties. Due to the intense hydration reaction of cement, the introduction of polymer emulsions slows down cement hydration. In actual construction, excessively high coating viscosity and a short open time can severely affect the construction progress and, after film formation, affect the film's density and adhesion to the substrate.

[0004] In the prior art, Swiss company Asada disclosed in patent document CN116438266A an open-time additive composition comprising at least two different imidazole-containing ketones. The performance of the open-time additive was characterized by testing the wet-edge to open-time ratio, open time, and touch-drying time by changing the substituents to oleate groups. Hunan Fuxiang Coatings & Chemicals Technology Co., Ltd. disclosed in patent document CN102627898B a waterborne coating with a long open time and its preparation method. This method involves first preparing an isocyanate polyurethane prepolymer, adding it to an acrylate polymer, and then supplementing it with powder to obtain a waterborne coating with low VOC content and a long open and wet-edge time, which is particularly helpful for surface leveling and film formation. However, the above two methods require complex and expensive additive synthesis steps. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a polymer emulsion, a preparation method thereof, and its application in the preparation of thick-film polymer cement coatings.

[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 polymer emulsion, which is prepared from raw materials comprising: monomers, emulsifiers, initiators, and additives;

[0008] The monomers include styrene, butyl acrylate, isooctyl acrylate, and functional monomers, wherein the functional monomers include acrylamide, methacrylic acid, and β-acryloyloxypropionic acid;

[0009] The additives include retarders and dispersants.

[0010] In some embodiments, the functional monomer accounts for 2 to 3% of the total weight of the monomer;

[0011] In some embodiments, the weight ratio of acrylamide, methacrylic acid, and β-acryloyloxypropionic acid in the functional monomer is 1:0.07-0.2:0.07-0.2;

[0012] In some embodiments, the weight ratio of styrene, butyl acrylate, and isooctyl acrylate in the monomer is 13-15:34-35:3.5-4;

[0013] In some embodiments, the emulsifier accounts for 0.39% to 0.62% of the total weight of the polymer emulsion, including anionic and nonionic emulsifiers in a mass ratio of 0.9 to 3:1.

[0014] In some embodiments, the initiator accounts for 0.5% to 1% of the total weight of the monomer;

[0015] In some embodiments, the retarder accounts for 0.2% to 0.5% of the total weight of the polymer emulsion;

[0016] In some embodiments, the dispersant accounts for 0.2% to 0.5% of the total weight of the polymer emulsion.

[0017] In some embodiments, the anionic emulsifier is selected from one or two of alkyl diphenyl ether sulfonate, sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl polyoxyethylene ether sulfate, and ethoxylated alkyl sulfate.

[0018] Specifically, alkyl diphenyl ether sulfonates such as sodium dodecyl diphenyl ether disulfonate (CAS No. 28519-02-0) and ethoxylated alkyl sulfates such as sodium lauryl ether sulfate (CAS No. 9004-82-4).

[0019] In some embodiments, the nonionic emulsifier is selected from one or two of ethylene glycol monostearate, ethylene glycol distearate, diethylene glycol monostearate, diethylene glycol distearate, polyethylene glycol 400 monostearate, polyethylene glycol 400 distearate, and polyethylene glycol 6000 distearate.

[0020] In some embodiments, the initiator is a persulfate or azo initiator;

[0021] In some embodiments, the retarder is selected from at least one of hydroxy acids and their salts, sugary carbohydrates, inorganic salts, and lignin sulfonates.

[0022] Specifically, retarders include one or more of the following: hydroxy acids and their salts, such as tartaric acid, citric acid, gluconic acid and their salts, as well as salicylic acid; sugary carbohydrates, such as molasses, glucose, sucrose, etc.; inorganic salts, such as borates, phosphates, zinc salts, etc.; and lignin sulfonates, such as calcium lignosulfonate, sodium lignosulfonate, etc. Tartaric acid is preferred.

[0023] In some embodiments, the dispersant is an inorganic dispersant and / or an organic dispersant.

[0024] In this embodiment, the inorganic dispersant mainly achieves dispersion by altering and increasing the zeta potential of the colloidal particles to generate electrostatic repulsion. The organic dispersant, on the other hand, has less impact on the zeta potential of the colloidal particles and primarily achieves dispersion through steric stabilization.

[0025] In some embodiments, the initiator is sodium persulfate;

[0026] In some embodiments, the inorganic dispersant is selected from at least one of silicates and alkali metal phosphates;

[0027] Specifically, silicates, such as water glass; and alkali metal phosphates, such as sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate.

[0028] In some embodiments, the organic dispersant is selected from at least one of triethylhexylphosphate, sodium dodecyl sulfate, methylpentanol, sodium polyacrylate, cellulose derivatives, polyacrylamide, glucon, and fatty acid polyethylene glycol esters.

[0029] In some embodiments, the dispersant is an organic dispersant, preferably Polycarboxylate BLJ-5018F (ammonium polycarboxylate dispersant);

[0030] In some embodiments, the raw materials of the polymer emulsion further include an oxidant comprising 0.3% to 0.5% of the total weight of the monomers;

[0031] In some embodiments, the raw materials of the polymer emulsion further include a reducing agent comprising 0.2% to 0.4% of the total weight of the monomers;

[0032] In some embodiments, the raw materials of the polymer emulsion also include a neutralizing agent comprising 0.1% to 0.3% of the total weight of the polymer emulsion.

[0033] In some embodiments, the oxidant is selected from hydrogen peroxide, tert-butyl hydrogen peroxide, and cumene hydrogen peroxide, preferably tert-butyl hydrogen peroxide;

[0034] In some embodiments, the reducing agent is selected from one of isoascorbic acid, sodium formaldehyde sulfoxylate, sodium metabisulfite, sodium bisulfite, FF6M, L-ascorbic acid, and sodium ascorbate, preferably sodium bisulfite;

[0035] In some embodiments, the neutralizing agent is selected from sodium hydroxide, ammonia, triethylamine, dimethylethanolamine, and 2-amino-2-methylpropanol, preferably sodium hydroxide.

[0036] In another aspect, the present invention provides a method for preparing a polymer emulsion, comprising at least:

[0037] (1) Preparation of pre-emulsion: Mix emulsifier, monomer and deionized water and stir for 30 min to obtain the pre-emulsion;

[0038] (2) Preparation of bottom material: Deionized water is added to the reactor to obtain the bottom material;

[0039] (3) Polymerization reaction: Initiator a is added to the material at the bottom of the reactor under stirring. After 3 to 10 minutes, the pre-emulsion is added dropwise. After 1 to 3 hours, initiator b is added dropwise. The pre-emulsion and initiator b are added dropwise at the same time. The dropwise temperature is controlled at 87 to 89°C. After the dropwise addition is completed, heat preservation treatment is performed.

[0040] (4) Post-treatment: Add oxidant and reducing agent to eliminate residual monomer, add neutralizing agent to adjust pH, add auxiliary agent to obtain the polymer emulsion.

[0041] In step (1), the mass ratio of the amount of deionized water to the total amount of monomers is 3 to 3.5:13;

[0042] In step (2), the mass ratio of the amount of deionized water to the total amount of monomers is 5-6:13;

[0043] In step (3), the ratio of the amount of initiator a to the amount of initiator b is 3:1 to 5:1;

[0044] In step (3), the heat preservation treatment time is 30 to 120 minutes;

[0045] In step (3), the temperature of the heat preservation treatment is 87-89℃;

[0046] In step (4), the oxidant is added in the form of an aqueous solution;

[0047] In step (4), the reducing agent is added in the form of an aqueous solution;

[0048] In step (4), the neutralizing agent is added in the form of an aqueous solution.

[0049] In a third aspect, the present invention also provides a method for applying a polymer emulsion in the preparation of a thick-film polymer cement coating, comprising: preparing the polymer emulsion into a liquid and mixing it with powder at a liquid-to-powder ratio of 1:1.8 to obtain the thick-film polymer cement coating.

[0050] The liquid component comprises: 90%–99% polymer emulsion, 1%–10% H2O, 0.1%–0.5% dispersant SN-Dispersant 5040, and 0.1%–0.4% defoamer SN-DEFOAMER NXZ;

[0051] The powder material includes: 30%–50% PO42.5 cement, 15%–25% 200-mesh quartz powder, 25%–35% 80–120-mesh quartz sand, and 10%–20% 400-mesh heavy calcium carbonate.

[0052] The reagents and raw materials used in this invention are all commercially available.

[0053] The positive and progressive effects of this invention are as follows:

[0054] 1. The thick-film polymer cement coating formulated with the polymer emulsion of this invention can achieve the required standard thickness in a single application. This invention also synthesizes the polymer emulsion using a special process by adjusting the dosage and ratio of emulsifier and functional monomers. Specifically, this invention adds a large amount of initiator at the initial stage of the reaction, which generates a large number of primary free radicals upon heating. A pre-emulsion is then added dropwise after 3-10 minutes, and the primary free radicals initiate monomer polymerization at different locations, generating latex particles. The polymer emulsion obtained by this process has low viscosity and coarse particle size, which helps to reduce the initial viscosity of the subsequent slurry. This method allows the two-component coating, which is combined with cement and other inorganic powders, to shorten the drying time difference between the surface and the interior during use, thereby solving the cracking problem.

[0055] 2. This invention can reduce the initial viscosity of the slurry and inhibit the increase of viscosity by adding readily available and inexpensive additives, which can extend the working time of workers and bring convenience in actual construction. Detailed Implementation

[0056] The present invention will now be described in detail with reference to embodiments, providing a clear and complete description of the technical solutions to facilitate understanding of the invention by those skilled in the art. The described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; and all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.

[0057] Example 1

[0058] Preparation of pre-emulsion: Add emulsifier (0.06 parts sodium lauryl ether sulfate, 0.216 parts sodium dodecyl diphenyl ether disulfonate, 0.1 parts polyethylene glycol 400 distearate) to 12 parts deionized water, stir for 10 min, then add 1.0 part acrylamide, 13.2 parts styrene, 34.17 parts butyl acrylate, 3.95 parts isooctyl acrylate, 0.07 parts methacrylic acid, and 0.07 parts β-acryloyloxypropionic acid in sequence, and stir at 200-300 rpm for 30 min.

[0059] Preparation of materials at the bottom of the reactor: Add 22 parts of deionized water to the reactor and heat it to 87-89℃.

[0060] Polymerization reaction preparation: Add sodium persulfate initiator (0.21 parts sodium persulfate dissolved in 0.67 parts deionized water) to the reactor under stirring. After 5 minutes, start adding pre-emulsion dropwise. After 2 hours, add sodium persulfate initiator (0.07 parts sodium persulfate dissolved in 2.53 parts deionized water). The total dropwise addition time is 4 hours, and the temperature is maintained at 87-89℃.

[0061] Incubation stage: After the dripping is completed, keep warm at 87-89℃ for 90 minutes.

[0062] Residual monomer removal stage: Cool to 78°C and use 0.18 parts tert-butyl hydroperoxide (dissolved in 2 parts deionized water) and 0.12 parts sodium bisulfite (dissolved in 2 parts deionized water).

[0063] Subsequent additions: Cool to below 40℃, add 0.2 parts tartaric acid and 0.2 parts BLJ-5018F, then add 0.1 parts sodium hydroxide to neutralize the pH to 7-9, and adjust the solid content to 55% to obtain the polymer emulsion.

[0064] Pulp preparation: Prepare the liquid material according to the liquid material application formula in Table 1. Under stirring, slowly add the powder material at a liquid-to-powder ratio of 1:1.8 and stir at 800 rpm for 5 minutes to obtain the polymer cement coating.

[0065] Table 1 Polymer Cement Coating Formulation

[0066] Example 2

[0067] Preparation of pre-emulsion: Add emulsifier (0.1 part sodium lauryl ether sulfate, 0.22 part sodium dodecyl diphenyl ether disulfonate, 0.16 part polyethylene glycol 400 distearate) to 12 parts deionized water and stir for 10 min. Then add 1.0 part acrylamide, 13.2 parts styrene, 35.0 parts butyl acrylate, 3.95 parts isooctyl acrylate, 0.12 parts methacrylic acid, and 0.2 parts β-acryloyloxypropionic acid in sequence and stir at 200-300 rpm for 30 min.

[0068] Preparation of materials at the bottom of the reactor: Add 22 parts of deionized water to the reactor and heat it to 87-89℃.

[0069] Polymerization reaction preparation: Add sodium persulfate initiator (0.21 parts sodium persulfate dissolved in 0.67 parts deionized water) to the reactor under stirring. After 5 minutes, start adding pre-emulsion dropwise. After 2 hours, add sodium persulfate initiator (0.07 parts sodium persulfate dissolved in 2.53 parts deionized water). The total dropwise addition time is 4 hours, and the temperature is maintained at 87-89℃.

[0070] Incubation stage: After the dripping is completed, keep warm at 87-89℃ for 90 minutes.

[0071] Residual monomer removal stage: Cool to 78°C and use 0.25 parts tert-butyl hydroperoxide (dissolved in 2 parts deionized water) and 0.16 parts sodium bisulfite (dissolved in 2 parts deionized water).

[0072] Subsequent additions: Cool to below 40℃, add 0.2 parts tartaric acid and 0.2 parts BLJ-5018F, then add 0.15 parts sodium hydroxide to neutralize the pH to 7-9, and adjust the solid content to 55% to obtain the polymer emulsion.

[0073] Pulp preparation: Prepare the liquid material according to the liquid material application formula in Table 1. Under stirring, slowly add the powder material at a liquid-to-powder ratio of 1:1.8 and stir at 800 rpm for 5 minutes to obtain the polymer cement coating.

[0074] Example 3

[0075] Preparation of pre-emulsion: Add emulsifier (0.06 parts sodium lauryl ether sulfate, 0.216 parts sodium dodecyl diphenyl ether disulfonate, 0.16 parts polyethylene glycol 400 distearate) to 12 parts deionized water, stir for 10 min, then add 1.0 part acrylamide, 15.0 parts styrene, 34.17 parts butyl acrylate, 3.95 parts isooctyl acrylate, 0.07 parts methacrylic acid, and 0.2 parts β-acryloyloxypropionic acid in sequence, and stir at 200-300 rpm for 30 min.

[0076] Preparation of materials at the bottom of the reactor: Add 22 parts of deionized water to the reactor and heat it to 87-89℃.

[0077] Polymerization reaction preparation: Add sodium persulfate initiator (0.28 parts sodium persulfate dissolved in 0.67 parts deionized water) to the reactor under stirring. After 5 minutes, start adding pre-emulsion dropwise. After 2 hours, add sodium persulfate initiator (0.07 parts sodium persulfate dissolved in 2.53 parts deionized water). The total dropwise addition time is 4 hours, and the temperature is maintained at 87-89℃.

[0078] Incubation stage: After the dripping is completed, keep warm at 87-89℃ for 90 minutes.

[0079] Residual monomer removal stage: Cool to 78°C and use 0.18 parts tert-butyl hydroperoxide (dissolved in 2 parts deionized water) and 0.12 parts sodium bisulfite (dissolved in 2 parts deionized water).

[0080] Subsequent additions: Cool to below 40℃, add 0.4 parts tartaric acid and 0.2 parts BLJ-5018F, then add 0.13 parts sodium hydroxide to neutralize the pH to 7-9, and adjust the solid content to 55% to obtain the polymer emulsion.

[0081] Pulp preparation: Prepare the liquid material according to the liquid material application formula in Table 1. Under stirring, slowly add the powder material at a liquid-to-powder ratio of 1:1.8 and stir at 800 rpm for 5 minutes to obtain the polymer cement coating.

[0082] Example 4

[0083] Preparation of pre-emulsion: Add emulsifier (0.06 parts sodium lauryl ether sulfate, 0.22 parts sodium dodecyl diphenyl ether disulfonate, 0.1 parts polyethylene glycol 400 distearate) to 12 parts deionized water and stir for 10 min. Then add 1.0 part acrylamide, 15.0 parts styrene, 34.17 parts butyl acrylate, 3.95 parts isooctyl acrylate, 0.12 parts methacrylic acid, and 0.07 parts β-acryloyloxypropionic acid in sequence and stir at 200-300 rpm for 30 min.

[0084] Preparation of materials at the bottom of the reactor: Add 22 parts of deionized water to the reactor and heat it to 87-89℃.

[0085] Polymerization reaction preparation: Add sodium persulfate initiator (0.35 parts sodium persulfate dissolved in 0.67 parts deionized water) to the reactor under stirring. After 5 minutes, start adding pre-emulsion dropwise. After 2 hours, add sodium persulfate initiator (0.07 parts sodium persulfate dissolved in 2.53 parts deionized water). The total dropwise addition time is 4 hours, and the temperature is maintained at 87-89℃.

[0086] Incubation stage: After the dripping is completed, keep warm at 87-89℃ for 90 minutes.

[0087] Residual monomer removal stage: Cool to 78°C and use 0.18 parts tert-butyl hydroperoxide (dissolved in 2 parts deionized water) and 0.12 parts sodium bisulfite (dissolved in 2 parts deionized water).

[0088] Subsequent additions: Cool to below 40℃, add 0.2 parts tartaric acid and 0.4 parts BLJ-5018F, then add 0.13 parts sodium hydroxide to neutralize the pH to 7-9, and adjust the solid content to 55% to obtain the polymer emulsion.

[0089] Pulp preparation: Prepare the liquid material according to the liquid material application formula in Table 1. Under stirring, slowly add the powder material at a liquid-to-powder ratio of 1:1.8 and stir at 800 rpm for 5 minutes to obtain the polymer cement coating.

[0090] The present invention also provides the following comparative examples.

[0091] Comparative Example 1

[0092] The only differences from Example 1 are: 1. In the preparation of the pre-emulsion, 0.07 parts of methacrylic acid and 0.07 parts of β-acryloyloxypropionic acid are replaced with 0.14 parts of acrylic acid; 2. In the post-addition step, the weight of sodium hydroxide is 0.2 parts.

[0093] Comparative Example 2

[0094] The only differences from Example 2 are: 1. In the preparation of the pre-emulsion, the weight of butyl acrylate is 34.17 parts; 2. In the post-addition step, BLJ-5018F is not added, and the weight of sodium hydroxide is 0.12 parts.

[0095] Comparative Example 3

[0096] The only differences from Example 3 are: 1. In the preparation of the pre-emulsion, the weight parts of polyethylene glycol 400 distearate are 0.3 parts and the weight parts of butyl acrylate are 35.0 parts; 2. In the post-addition step, tartaric acid and BLJ-5018F are not added, and the weight parts of sodium hydroxide are 0.1 parts.

[0097] Comparative Example 4

[0098] The only differences from Example 4 are: 1. No methacrylic acid was added in the preparation of the pre-emulsion step; 2. In the post-addition step, the weight of BLJ-5018F was 0.2 parts.

[0099] Comparative Example 5

[0100] The only differences from Example 4 are: 1. β-Acryloyloxypropionic acid was not added in the preparation of the pre-emulsion step; 2. 2 parts of the emulsion and 0.35 parts of sodium persulfate were added to the reactor in the polymerization step.

[0101] Comparative Example 6

[0102] The product is a commercially available product, model number 7366, manufactured by BADF.

[0103] Product performance testing

[0104] The polymer cement coatings prepared in Examples 1-4 and Comparative Examples 1-6 were tested according to the following standards or methods:

[0105] I. Tensile Strength and Elongation at Break Tests: The polymer cement coatings prepared in the examples and comparative examples were poured into molds specified in the GB / T 16777-2008 standard document and applied in two coats. The subsequent coat should be applied after the previous coat has fully dried, with an interval of 12–24 hours between coats, to achieve a coating thickness of 1.5 ± 0.2 mm. After smoothing the surface of the final coat, the samples were allowed to stand at 23 ± 2℃ and (50 ± 10)% relative humidity for 96 hours. Then, the samples were demolded, reversed, and treated in a drying oven at 40 ± 2℃ for 48 hours. After removal, they were placed in a desiccator to cool to room temperature. The samples were cut into specimens using a CP-25A slicer from Shanghai Dengjie Machinery Equipment, with the specimen shape being the type I dumbbell shape specified in the GB / T 528-1998 standard document. The tensile strength and elongation at break of the specimens were tested using an LD23.104 microcomputer-controlled electronic universal testing machine from Shanghai Lisheng Scientific Instruments.

[0106] II. Slurry Viscosity Test: Based on the simplicity of open time testing methods, this invention uses the change in coating viscosity over a certain time interval to reflect whether the open time has improved. This invention chooses the change in coating viscosity before and after 30 minutes to reflect the quality of the open time. Generally speaking, the smaller the change in coating viscosity within 30 minutes, the longer the open time. The specific method is as follows: Under a constant temperature and humidity environment (temperature 25℃, humidity 50%), the initial viscosity (4# 30r) of the above-prepared coating is tested using a Brookfield viscometer. After 30 minutes, the dried skin on the surface is removed, and the coating viscosity (4# 30r) is tested again.

[0107] III. Coating Test: Apply 2mm and 4mm coatings to the calcium silicate board and observe the cracking after the coating dries.

[0108] The products prepared in Examples 1-4 and Comparative Examples 1-6 were subjected to performance testing, and the results are shown in Table 2.

[0109] Table 2 Performance Test Results

[0110] As shown in Table 2, a comparison of Example 1 with Comparative Examples 1 and 4 reveals that methacrylic acid and β-acryloyloxypropionic acid synergistically alter the surface properties of the polymer emulsion, resulting in carboxyl groups on the surface of the polymer latex particles. This enhances their adsorption capacity on the cement particle surface, leading to calcium ion accumulation through complexation, reducing internal stress in the cement coating, and thus inhibiting cracking. In contrast, coatings made solely using acrylic monomers exhibited cracking even with thick application.

[0111] The results from Examples 1, 3, and Comparative Example 2 show that tartaric acid, a flocculant, can reduce the initial viscosity of the slurry, and the more it is added, the more significant the reduction effect. However, for coatings with a high liquid-to-powder ratio, it cannot suppress the rapid increase in slurry viscosity in the later stages. Therefore, this invention can significantly suppress the increase in slurry viscosity and extend the open time by adding dispersant BLJ-5018F. Comparative Example 3 shows that the simultaneous lack of both flocculant tartaric acid and dispersant BLJ-5018F resulted in a high initial viscosity and the largest increase in viscosity, leading to the worst open time. However, the dosage of both must be controlled within a certain range; excessive amounts will reduce the adhesion between the coating and the substrate. This may cause the coating to peel, detach, or blister easily, thus affecting the durability and quality of the coating. Furthermore, excessive dispersant may damage the stability of the coating, causing phase separation, coagulation, or precipitation. This may cause the coating to lose its uniformity, making it difficult to coat or use normally.

[0112] Based on the results of Examples 4, 5, and 6, it is evident that Comparative Example 5, employing other polymerization processes, negatively impacted both the open time and thick-coat crack resistance. In contrast, the polymerization process of this invention improved the thick-coat crack resistance and reduced the viscosity rise. While this invention is similar to commercially available product 7366 in terms of thick-coat crack resistance, its viscosity rise is significantly lower than that of product 7366 in improving open time. Therefore, this application demonstrates a significantly superior effect in improving open time compared to commercially available product 7366 emulsion.

[0113] 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.

[0114] 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 polymer emulsion, characterized in that, The polymer emulsion is prepared from the following raw materials: monomer, emulsifier, initiator and additives; The monomers include styrene, butyl acrylate, isooctyl acrylate, and functional monomers, wherein the functional monomers include acrylamide, methacrylic acid, and β-acryloyloxypropionic acid; The additives include retarders and dispersants.

2. The polymer emulsion according to claim 1, characterized in that, The functional monomer accounts for 2-3% of the total weight of the monomer; And / or, the weight ratio of acrylamide, methacrylic acid and β-acryloyloxypropionic acid in the functional monomer is 1:0.07-0.2:0.07-0.2; And / or, the weight ratio of styrene, butyl acrylate, and isooctyl acrylate in the monomer is 13-15:34-35:3.5-4; And / or, the emulsifier accounts for 0.39% to 0.62% of the total weight of the polymer emulsion, including anionic emulsifiers and nonionic emulsifiers in a mass ratio of 0.9 to 3:1; And / or, the initiator accounts for 0.5% to 1% of the total weight of the monomer; And / or, the retarder accounts for 0.2% to 0.5% of the total weight of the polymer emulsion; And / or, the dispersant accounts for 0.2% to 0.5% of the total weight of the polymer emulsion.

3. The polymer emulsion according to claim 2, characterized in that, The anionic emulsifier is selected from one or two of alkyl diphenyl ether sulfonate, sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl polyoxyethylene ether sulfate, and ethoxylated alkyl sulfate. And / or, the nonionic emulsifier is selected from one or two of ethylene glycol monostearate, ethylene glycol distearate, diethylene glycol monostearate, diethylene glycol distearate, polyethylene glycol 400 monostearate, polyethylene glycol 400 distearate, and polyethylene glycol 6000 distearate. And / or, the initiator is a persulfate or azo initiator; And / or, the retarder is selected from at least one of hydroxy acids and their salts, sugar-containing carbohydrates, inorganic salts, and lignin sulfonates, preferably tartaric acid; And / or, the dispersant is an inorganic dispersant and / or an organic dispersant.

4. The polymer emulsion according to claim 3, characterized in that, The initiator is sodium persulfate; And / or, the inorganic dispersant is selected from at least one of silicates and alkali metal phosphates; And / or, the organic dispersant is selected from at least one of triethylhexylphosphate, sodium dodecyl sulfate, methylpentanol, sodium polyacrylate, cellulose derivatives, polyacrylamide, glucon, and fatty acid polyethylene glycol esters.

5. The polymer emulsion according to claim 3, characterized in that, The dispersant is an organic dispersant, preferably Baolijia BLJ-5018F; And / or, the raw materials of the polymer emulsion further include an oxidant comprising 0.3% to 0.5% of the total weight of the monomers; And / or, the raw materials of the polymer emulsion further include a reducing agent accounting for 0.2% to 0.4% of the total weight of the monomers; And / or, the raw materials of the polymer emulsion also include a neutralizing agent comprising 0.1% to 0.3% of the total weight of the polymer emulsion.

6. The polymer emulsion according to claim 5, characterized in that, The oxidant is selected from hydrogen peroxide, tert-butyl hydrogen peroxide, and cumene hydrogen peroxide, preferably tert-butyl hydrogen peroxide; And / or, the reducing agent is selected from one of isoascorbic acid, sodium formaldehyde sulfoxylate, sodium metabisulfite, sodium bisulfite, FF6M, L-ascorbic acid, and sodium ascorbate, preferably sodium bisulfite; And / or, the neutralizing agent is selected from sodium hydroxide, ammonia, triethylamine, dimethylethanolamine, and 2-amino-2-methylpropanol, preferably sodium hydroxide.

7. A method for preparing a polymer emulsion as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Preparation of pre-emulsion: Mix emulsifier, monomer and deionized water and stir for 30 min to obtain the pre-emulsion; (2) Preparation of bottom material: Deionized water is added to the reactor to obtain the bottom material; (3) Polymerization reaction: Initiator a is added to the material at the bottom of the reactor under stirring. After 3 to 10 minutes, the pre-emulsion is added dropwise. After 1 to 3 hours, initiator b is added dropwise. The pre-emulsion and initiator b are added dropwise at the same time. The dropwise temperature is controlled at 87 to 89°C. After the dropwise addition is completed, heat preservation treatment is performed. (4) Post-treatment: Add oxidant and reducing agent to eliminate residual monomer, add neutralizing agent to adjust pH, add auxiliary agent to obtain the polymer emulsion.

8. The method for preparing the polymer emulsion according to claim 7, characterized in that, The preparation method satisfies at least one of the following conditions: In step (1), the mass ratio of the amount of deionized water to the total amount of monomers is 3 to 3.5:13; In step (2), the mass ratio of the amount of deionized water to the total amount of monomers is 5-6:13; In step (3), the ratio of the amount of initiator a to the amount of initiator b is 3:1 to 5:1; In step (3), the heat preservation treatment time is 30 to 120 minutes; In step (3), the temperature of the heat preservation treatment is 87-89℃; In step (4), the oxidant is added in the form of an aqueous solution; In step (4), the reducing agent is added in the form of an aqueous solution; In step (4), the neutralizing agent is added in the form of an aqueous solution.

9. A method for applying the polymer emulsion as described in claims 1-6 in the preparation of thick-film polymer cement coatings, characterized in that, include: The polymer emulsion is prepared into a liquid and then mixed with the powder at a liquid-to-powder ratio of 1:1.8 to obtain the thick-coat polymer cement coating.

10. The method for applying the polymer emulsion according to claim 9 in the preparation of thick-film polymer cement coatings, characterized in that, The liquid component comprises: 90%–99% polymer emulsion, 1%–10% H2O, 0.1%–0.5% dispersant SN-Dispersant 5040, and 0.1%–0.4% defoamer SN-DEFOAMER NXZ; And / or, the powder comprises: 30%–50% PO42.5 cement, 15%–25% 200-mesh quartz powder, 25%–35% 80–120-mesh quartz sand, and 10%–20% 400-mesh heavy calcium carbonate.

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