Polymer emulsion, preparation method therefor, and use thereof

Abstract

The present invention provides a polymer emulsion, which is prepared by emulsion polymerization of polymerizable monomers in the presence of an emulsifier, the polymerizable monomers comprising at least 20 wt.% of an itaconic acid diester monomer, and the emulsifier comprising a sulfosuccinate emulsifier. Further provided are a preparation method for and a use of the polymer emulsion. Also provided are a coating prepared from the polymer emulsion. In the polymer emulsion provided in the present invention, by using a specific type of emulsifier, the proportion of the itaconic acid ester monomer in the polymerizable monomers can be greatly increased, thereby improving the proportion of bio-based materials and reducing the pressure on resources and the environment. The polymer emulsion provided in the present invention has excellent performance, good economic efficiency, is green and environmentally friendly, and has a simple preparation process that is easy to operate and control, and is therefore very suitable for large-scale production and use.

Description

A polymer emulsion, its preparation method and uses Technical Field

[0001] This invention relates to the field of polymers, specifically to a polymer emulsion, and also to a method for preparing the polymer emulsion and its uses. Background Technology

[0002] Bio-based materials are materials manufactured using renewable resources (including the contents and residues of crops, trees, and other plants and animals) through biological, chemical, and physical methods. They are characterized by being green, environmentally friendly, using renewable raw materials, and being biodegradable. Furthermore, the production of bio-based materials does not require the use of non-renewable resources such as petroleum, reducing dependence on these resources and thus lessening environmental pressure.

[0003] In the coatings industry, there is growing interest in using renewable resources to create environmentally friendly products and methods. Itaconic acid and its ester derivatives have attracted significant attention in the preparation of bio-based emulsions due to their potential for 100% bio-based origin. However, the polymerization of itaconic esters has remained a challenge, especially in emulsion polymerization. When the proportion of itaconic ester monomers is high, they are difficult to emulsify and exhibit poor polymerization conversion, leading to difficult or unstable emulsion preparation. A common approach is to add large amounts of carboxyl-containing monomers, such as methacrylic acid, to improve the conversion rate and stability of itaconic esters.

[0004] Patent US2009 / 0286947 studied the conversion rate of itaconic acid and its esters. By increasing the proportion of carboxylic acid functional groups, a higher conversion rate can be obtained, but the increase of carboxylic acid functional groups will significantly limit the use of the composition. Patent US 3321431 uses more than 10% of water-soluble organic solvent to enhance the polymerization ability of itaconic acid esters, but in conventional emulsion polymerization, more than 10% of organic solvent is itself an unstable factor. Patent CN 102656201A increases the proportion of itaconic acid esters by preparing specific oligomers containing itaconic acid esters and then carrying out emulsion polymerization of the remaining monomers on this basis, but this can only be applied to specific systems and is not universal.

[0005] Summary of the Invention

[0006] To overcome the shortcomings of the prior art, one object of the present invention is to provide a polymer emulsion based on a large amount of itaconic acid ester monomers, with a high proportion of bio-based materials. The resulting emulsion has good stability and can achieve excellent coating performance when used in coatings.

[0007] Another object of the present invention is to provide a method for preparing the polymer emulsion and its uses.

[0008] Another object of the present invention is to provide a coating.

[0009] A first aspect of the present invention provides a polymer emulsion prepared by emulsion polymerization of polymeric monomers in the presence of an emulsifier, wherein the polymeric monomers comprise:

[0010] (a) 20 to 70 parts by weight of itaconic acid diester monomer;

[0011] (b) 0.5 to 5 parts by weight of a crosslinkable monomer containing at least two vinyl functional groups;

[0012] (c) 0.5 to 5 parts by weight of a vinyl unsaturated monomer containing at least one carboxylic acid functional group;

[0013] (d) 25 to 75 parts by weight of a vinyl unsaturated monomer different from (a), (b) and (c); wherein the itaconic acid diester monomer accounts for at least 20 wt.% of the total weight of the polymeric monomer; and the emulsifier includes a sulfosuccinate emulsifier.

[0014] The inventors of this invention have discovered that sulfosuccinate emulsifiers have excellent affinity for itaconic acid ester monomers. Compared to other types of emulsifiers, these emulsifiers facilitate pre-emulsification, increasing the proportion of itaconic acid ester monomers in the polymer monomers to over 20%, thereby increasing the proportion of bio-based materials in the polymer emulsion, and the resulting emulsion also exhibits good stability. Furthermore, the inventors have found that adding a certain amount of crosslinkable monomers containing at least two vinyl functional groups to the polymer monomers can compensate for the performance deficiencies caused by carboxylic acid functional groups, such as chemical resistance.

[0015] In the polymer emulsion provided by the present invention, the itaconic acid diester monomer accounts for at least 20 wt.% of the total weight of the polymer monomers, for example, at least 25 wt.%, at least 30 wt.%, at least 35 wt.%, at least 40 wt.%, at least 45 wt.%, at least 50 wt.%, at least 55 wt.%, at least 60 wt.%, at least 65 wt.%, at least 70 wt.%, etc., and may even be higher.

[0016] In the polymer emulsion provided by this invention, the sulfosuccinate emulsifier can be any type commonly found in the art, and can be the corresponding sodium salt, potassium salt, or ammonium salt. In some preferred embodiments, the sulfosuccinate emulsifier can be further classified as a sodium sulfosuccinate emulsifier, including but not limited to one or more of sodium monoalkyl sulfosuccinate, sodium dialkyl sulfosuccinate, sodium ethoxylated alcohol monoalkyl sulfosuccinate, sodium ethoxylated alcohol dialkyl sulfosuccinate, and sodium alkylamide sulfosuccinate, wherein the alkyl group can be a C4-C18 straight-chain or branched alkyl group, and the number of ethoxy units contained can be 2-8. In some preferred embodiments, the sulfosuccinate emulsifier may be one or more of sodium dialkyl sulfosuccinate (wherein the alkyl group may be a C4-C6 straight-chain or branched alkyl group), sodium ethoxylated alcohol monoalkyl sulfosuccinate (wherein the alkyl group may be a C12-C14 straight-chain or branched alkyl group, and the number of ethoxy units may be 4-6), and sodium alkylamide sulfosuccinate (wherein the alkyl group may be a C16-C18 straight-chain or branched alkyl group). In some most preferred embodiments, the sulfosuccinate emulsifier may be one or more of the emulsifiers with the brand names AY-65, DES-30, and 18-P.

[0017] In the polymer emulsion provided by the present invention, in addition to sulfosuccinate emulsifiers, the emulsifier may also include other types of emulsifiers commonly used in the art, such as dodecyl sulfate emulsifiers (e.g., sodium dodecyl sulfate), dodecyl sulfonate emulsifiers (e.g., sodium dodecyl sulfonate), dodecylbenzene sulfonate emulsifiers (e.g., sodium dodecylbenzene sulfonate), fatty alcohol polyoxyethylene ether sulfate emulsifiers (e.g., sodium dodecyl polyoxyethylene ether (2-20) sulfate), fatty alcohol polyoxyethylene ether sulfonate emulsifiers (e.g., sodium dodecyl polyoxyethylene ether (2-20) sulfonate), and fatty alcohol polyoxyethylene ether phosphate emulsifiers (e.g., sodium dodecyl polyoxyethylene ether (3-10) phosphate).

[0018] In the polymer emulsion provided by the present invention, the emulsifier may include a first emulsifier and a second emulsifier. The first emulsifier is used to form a pre-emulsion with the polymer monomer, and the second emulsifier is used to be added to the bottom of the polymerization reactor. The first emulsifier may contain sulfosuccinate emulsifiers, or the first emulsifier may be only sulfosuccinate emulsifiers. The second emulsifier may contain sulfosuccinate emulsifiers and other types of emulsifiers, or it may be only other types of emulsifiers.

[0019] In the polymer emulsion provided by the present invention, the amount of the emulsifier can be 0.5 to 5 parts by weight, for example, about 0.5 parts by weight, about 1 part by weight, about 1.5 parts by weight, about 2 parts by weight, about 2.5 parts by weight, about 3 parts by weight, about 3.5 parts by weight, about 4 parts by weight, about 4.5 parts by weight, about 5 parts by weight, or any weight range. In some preferred embodiments, based on the total weight of the emulsifier, the sulfosuccinate emulsifier can be 10 to 100 wt.%, for example, about 10 wt.%, about 20 wt.%, about 30 wt.%, about 40 wt.%, about 50 wt.%, about 60 wt.%, about 70 wt.%, about 80 wt.%, about 90 wt.%, about 100 wt.%, or any weight percentage range. In some more preferred embodiments, based on the total weight of the emulsifier, the sulfosuccinate emulsifier can be 40 to 80 wt.%.

[0020] In the polymer emulsion provided by this invention, the itaconic acid diester monomer can be selected from one or more of dimethyl itaconic acid, diethyl itaconic acid, dibutyl itaconic acid, and dioctyl itaconic acid. The amount of the itaconic acid diester monomer can be about 20 parts by weight, about 30 parts by weight, about 40 parts by weight, about 50 parts by weight, about 60 parts by weight, about 70 parts by weight, or any range of parts by weight. In some preferred embodiments, the itaconic acid diester monomer can be of bio-based origin.

[0021] In the polymer emulsion provided by this invention, the crosslinkable monomer containing at least two vinyl functional groups may be selected from one or more of allyl methacrylate, diallyl phthalate, ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane trimethacrylate, divinylbenzene, trimethylolpropane diallyl ether, and pentaerythritol triallyl ether. In some preferred embodiments, the crosslinkable monomer containing at least two vinyl functional groups may be selected from one or both of diallyl phthalate and ethylene glycol dimethacrylate. The amount of the crosslinkable monomer containing at least two vinyl functional groups can be about 0.5 parts by weight, about 1 part by weight, about 1.5 parts by weight, about 2 parts by weight, about 2.5 parts by weight, about 3 parts by weight, about 3.5 parts by weight, about 4 parts by weight, about 4.5 parts by weight, about 5 parts by weight, or any range of parts by weight.

[0022] In the polymer emulsion provided by this invention, the vinyl unsaturated monomer containing at least one carboxylic acid functional group can be selected from one or more of (meth)acrylic acid, itaconic acid, fumaric acid, and aconitic acid. In some preferred embodiments, the vinyl unsaturated monomer containing at least one carboxylic acid functional group can be selected from one or two of acrylic acid and methacrylic acid. The amount of the vinyl unsaturated monomer containing at least one carboxylic acid functional group can be about 0.5 parts by weight, about 1 part by weight, about 1.5 parts by weight, about 2 parts by weight, about 2.5 parts by weight, about 3 parts by weight, about 3.5 parts by weight, about 4 parts by weight, about 4.5 parts by weight, about 5 parts by weight, or any range of parts by weight.

[0023] In the polymer emulsion provided by this invention, the vinyl unsaturated monomers, which are different from (a), (b), and (c), may be selected from one or more of methyl methacrylate, ethyl methacrylate, butyl methacrylate, isooctyl methacrylate, and styrene. In some preferred embodiments, the vinyl unsaturated monomers, which are different from (a), (b), and (c), may be selected from one or two of methyl methacrylate and butyl acrylate. The amount of the vinyl unsaturated monomers, which are different from (a), (b), and (c), may be about 25 parts by weight, about 30 parts by weight, about 35 parts by weight, about 40 parts by weight, about 45 parts by weight, about 50 parts by weight, about 55 parts by weight, about 60 parts by weight, about 65 parts by weight, about 70 parts by weight, about 75 parts by weight, or any range of parts by weight.

[0024] A second aspect of the present invention provides a method for preparing the polymer emulsion according to any one of the foregoing technical solutions, the method comprising the following steps:

[0025] S1: Take 40-80 wt.% of the total weight of the emulsifier and the polymeric monomer, and dissolve them in water to prepare a pre-emulsion;

[0026] S2: Dissolve the remaining emulsifier in water, add the initiator at 75–95°C, and dropwise add the pre-emulsion to initiate emulsion polymerization; and

[0027] S3: After the emulsion polymerization is completed, an eliminator and a neutralizer are added in sequence, the solid content is adjusted and filtered to obtain the polymer emulsion.

[0028] In some preferred embodiments, the initiator may be selected from one or more of ammonium persulfate, potassium persulfate, and sodium persulfate. The amount of the initiator may be 0.1 to 1 part by weight, for example, about 0.1 part by weight, about 0.2 part by weight, about 0.3 part by weight, about 0.4 part by weight, about 0.5 part by weight, about 0.6 part by weight, about 0.7 part by weight, about 0.8 part by weight, about 0.9 part by weight, about 1 part by weight, or any range of parts by weight. In some more preferred embodiments, the initiator may be used in the form of an aqueous solution, for example, prepared as an aqueous solution with a concentration of 5 to 15 wt.%.

[0029] In some preferred embodiments, the post-elimination agent can be a redox system, wherein the oxidant can be tert-butyl hydroperoxide, and the reductant can be isoascorbic acid, and the amount of each can be 0.1 to 0.5 parts by weight, for example, about 0.1 parts by weight, about 0.2 parts by weight, about 0.3 parts by weight, about 0.4 parts by weight, about 0.5 parts by weight, or any range of parts by weight. In some more preferred embodiments, the oxidant and the reductant can each be used in the form of an aqueous solution, for example, each prepared as an aqueous solution with a concentration of 5 to 15 wt.%.

[0030] In some preferred embodiments, the neutralizing agent may be selected from one or more of ammonia, ethanolamine, and N,N-dimethylethanolamine. The amount of neutralizing agent used may be sufficient to adjust the pH of the polymerization system to near neutral or weakly alkaline, for example, to a pH of 7-9.

[0031] In some preferred embodiments, in step S1, the amount of water used to form the preemulsion can be 20 to 50 parts by weight (e.g., 30 to 40 parts by weight), and the temperature can be 0 to 20°C (e.g., 10 to 15°C).

[0032] In some preferred embodiments, in step S1, the emulsifier used to prepare the preemulsion includes a sulfosuccinate emulsifier, or it may be entirely a sulfosuccinate emulsifier.

[0033] In some preferred embodiments, in step S2, the amount of water used to dissolve the remaining emulsifier can be 80 to 100 parts by weight (e.g., 80 to 90 parts by weight).

[0034] In some preferred embodiments, in step S2, the pre-emulsion can be added dropwise over 2 to 6 hours (e.g., 2 to 4 hours), and after the addition is completed, the solution is kept warm for another 0.5 to 2 hours (e.g., 0.5 to 1 hour).

[0035] In some preferred embodiments, in step S2, the temperature during the addition of the preemulsifier and emulsion polymerization can be 80–90°C (e.g., 80–85°C).

[0036] In some preferred embodiments, in step S3, after the emulsion polymerization is completed, the temperature is lowered to 65-75°C, a post-elimination agent is added and the temperature is maintained for 0.5-2 hours (for example, 0.5-1 hour), then the temperature is lowered to below 45°C, a neutralizing agent is added to adjust the pH value to 7-9, the solid content is adjusted and filtered to obtain the polymer emulsion.

[0037] In some preferred embodiments, in step S3, the solid content of the polymer emulsion can be adjusted to 30-50 wt.%.

[0038] A third aspect of the present invention provides the use of the polymer emulsion described in any of the foregoing technical solutions for the preparation of coatings.

[0039] In some preferred embodiments, the coating may be a water-based coating. In some more preferred embodiments, the coating may be a wood coating.

[0040] A fourth aspect of the present invention provides a coating made from a polymer emulsion as described in any of the foregoing technical solutions.

[0041] In addition to polymer emulsions, the coatings described in this invention may also include any other commonly used components permitted in the art, including but not limited to neutralizers, film-forming aids, wetting agents, defoamers, thickeners, etc. Those skilled in the art can specifically select and adjust the components and their dosages based on conventional technical means in the art. The formulation process of the coating is also a commonly used process in the art and can be formulated by those skilled in the art using conventional methods.

[0042] In some preferred embodiments, the coating may be a water-based coating. In some more preferred embodiments, the coating may be a wood coating.

[0043] The technical solution provided by this invention has the following advantages:

[0044] (1) In the polymer emulsion provided by the present invention, by using a specific succinate emulsifier, the proportion of itaconic acid ester monomers in the polymer monomers can be significantly increased, thereby increasing the proportion of bio-based materials in the polymer emulsion and reducing the pressure on resources and the environment.

[0045] (2) The polymer emulsion provided by the present invention has good stability, and the coatings prepared therefrom also have excellent storage stability.

[0046] (3) The polymer emulsion provided by the present invention forms a crosslinking system by adding crosslinkable monomers containing at least two vinyl functional groups, which can significantly improve the coating's durability when used in coatings.

[0047] In summary, the polymer emulsion provided by this invention has excellent performance, good economic efficiency, is environmentally friendly, and has a simple preparation process that is easy to operate and control, making it very suitable for large-scale production and application. Detailed Implementation

[0048] The technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0049] The raw materials used in the embodiments and comparative examples of the present invention are shown in Table 1. Unless otherwise specified, other raw materials are commercially available products.

[0050] Unless otherwise specified, all percentages used in the embodiments and comparative examples of this invention are mass percentages.

[0051] Table 1. Abbreviations, chemical names, and manufacturers of each raw material.

[0052] Example 1: Preparation of Polymer Emulsion

[0053] The preparation process of polymer emulsions includes the following steps:

[0054] (1) Dissolve 18g of DES-30 (30% effective content) in 150g of water at 10℃, and then add 180g of DMI, 12g of AA, 10g of DAP, 200g of MMA and 98g of BA to the pre-emulsion tank in sequence and stir to form a pre-emulsion.

[0055] (2) Dissolve 2g of SDS in 450g of water, then add it to the reaction vessel and heat it until the temperature inside the reaction vessel stabilizes at 85℃;

[0056] (3) Add 30g of 10% APS aqueous solution to the reactor. After 5 minutes, start adding the pre-emulsion to the reactor. The addition is completed within 3 hours. After the addition is completed, maintain the reaction temperature for 1 hour.

[0057] (4) After the heat preservation is completed, the temperature inside the reactor is reduced to 70°C, and then 10g of t-BHP with a mass fraction of 10% and 10g of IAA with a mass fraction of 10% are added in sequence, and the temperature is maintained for 1 hour.

[0058] (5) After the second heat preservation is completed, the temperature is lowered to below 45℃, then DMEA is added to adjust the pH to 7-9, and the solid content of the emulsion is adjusted to 40±1%. After mixing evenly, the mixture is filtered through a 100-mesh filter and discharged.

[0059] Examples 2-7 and Comparative Examples 1-3

[0060] The emulsions in Examples 2-7 and Comparative Examples 1-3 were prepared using a method similar to that in Example 1, with the only difference being the amount of each raw material and the reaction temperature, as shown in Table 2.

[0061] In Comparative Examples 1-2, 5.4g of SDS or SDBS was used to prepare the pre-emulsion in step (1).

[0062] Table 2. Amounts of each raw material (in g) and reaction temperature in the examples and comparative examples.

[0063] The emulsions prepared in Examples 1-7 and Comparative Examples 1-3 were used to prepare varnishes according to the coating formulation table shown in Table 3. The performance of the emulsions was evaluated by the varnish coating.

[0064] Table 3 Varnish Formula Table Note: Raw materials without a specified manufacturer can be used interchangeably as long as they are of the same type.

[0065] According to the formula in Table 3, water, polymer emulsion, ammonia, dipropylene glycol methyl ether, diethylene glycol butyl ether, defoamer and thickener are added sequentially to the dispersion tank. Then, the mixture is stirred at 500 r / min for 10 min, and 4.9 g of water is added and stirred evenly to obtain the varnish.

[0066] Coating film performance evaluation

[0067] The varnishes prepared with the polymer emulsions prepared in Examples 1-7 and Comparative Examples 1-3 were evaluated for their film performance (reference standard: GB / T 3324-2017). The specific results are shown in Table 4.

[0068] Table 4 Evaluation Results of Coating Film Performance Note: A test result of 5 represents the best result, and a test result of 1 represents the worst result.

[0069] Compared to the emulsions in the examples, the emulsions in Comparative Examples 1-2, which did not use sulfosuccinate emulsifiers, showed more flocculents during discharge filtration. At the same time, the varnishes prepared using them also showed obvious precipitates after heat storage. This indicates that in the polymerization system containing a large amount of itaconic acid ester monomers, sulfosuccinate emulsifiers exhibit excellent emulsifying properties and also contribute to the improvement of paint film durability.

[0070] In addition, the results of the varnish film durability show that crosslinkable monomers significantly improve the durability of the film. As shown in Comparative Examples 1 and 2, although both produced a lot of precipitates, the durability of the film in Comparative Example 1 was significantly better than that in Comparative Example 2. As shown in Comparative Example 3, when using sulfosuccinate emulsifiers without adding crosslinkable monomers, the emulsification and stability were improved, but the durability of the film was not significantly improved.

[0071] Unless otherwise specified, the terms used in this invention have the meanings commonly understood by those skilled in the art.

[0072] The embodiments described in this invention are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Those skilled in the art can make various other substitutions, changes and improvements within the scope of this invention. Therefore, this invention is not limited to the above embodiments, but is only defined by the claims.

Claims

1. A polymer emulsion, prepared by emulsion polymerization of monomers in the presence of an emulsifier, characterized in that, The polymer monomers include: (a) 20 to 70 parts by weight of itaconic acid diester monomer; (b) 0.5 to 5 parts by weight of a crosslinkable monomer containing at least two vinyl functional groups; (c) 0.5 to 5 parts by weight of a vinyl unsaturated monomer containing at least one carboxylic acid functional group; (d) 25 to 75 parts by weight of vinyl unsaturated monomers different from (a), (b) and (c); The itaconic acid diester monomer accounts for at least 20 wt.% of the total weight of the polymer monomers; the emulsifier includes sulfosuccinate emulsifiers.

2. The polymer emulsion according to claim 1, characterized in that, The sulfosuccinate emulsifier is a sodium sulfosuccinate salt emulsifier, preferably one or more of sodium monoalkyl sulfosuccinate, sodium dialkyl sulfosuccinate, sodium ethoxylated alcohol monoalkyl sulfosuccinate, sodium ethoxylated alcohol dialkyl sulfosuccinate, and sodium alkylamide sulfosuccinate, wherein the alkyl group is a straight-chain or branched alkyl group of C4 to C18, and the number of ethoxy units is 2 to 8.

3. The polymer emulsion according to claim 1 or 2, characterized in that, The emulsifier also includes one or more of the following: dodecyl sulfate emulsifiers, dodecyl sulfonate emulsifiers, dodecylbenzene sulfonate emulsifiers, fatty alcohol polyoxyethylene ether sulfate emulsifiers, fatty alcohol polyoxyethylene ether sulfonate emulsifiers, and fatty alcohol polyoxyethylene ether phosphate emulsifiers; Preferably, the amount of the emulsifier is 0.5 to 5 parts by weight.

4. The polymer emulsion according to any one of claims 1-3, characterized in that, The itaconic acid diester monomer is selected from one or more of dimethyl itaconic acid, diethyl itaconic acid, dibutyl itaconic acid, and dioctyl itaconic acid. Preferably, the itaconic acid diester monomer is of bio-based origin.

5. The polymer emulsion according to any one of claims 1-4, characterized in that, The crosslinkable monomer containing at least two vinyl functional groups is selected from one or more of allyl methacrylate, diallyl phthalate, ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane trimethacrylate, divinylbenzene, trimethylolpropane diallyl ether, and pentaerythritol triallyl ether; preferably selected from one or two of diallyl phthalate and ethylene glycol dimethacrylate.

6. The polymer emulsion according to any one of claims 1-5, characterized in that, The vinyl unsaturated monomer containing at least one carboxylic acid functional group is selected from one or more of (meth)acrylic acid, itaconic acid, fumaric acid, and aconitic acid; preferably selected from one or two of acrylic acid and methacrylic acid.

7. The polymer emulsion according to any one of claims 1-6, characterized in that, The vinyl unsaturated monomers, which are different from those in (a), (b), and (c), are selected from one or more of methyl methacrylate, ethyl methacrylate, butyl methacrylate, isooctyl methacrylate, and styrene; preferably, they are selected from one or two of methyl methacrylate and butyl acrylate.

8. A method for preparing the polymer emulsion according to any one of claims 1-7, characterized in that, Includes the following steps: S1: Take 40-80 wt.% of the total weight of the emulsifier and the polymeric monomer, and dissolve them in water to prepare a pre-emulsion; S2: Dissolve the remaining emulsifier in water, add the initiator at 75–95°C, and dropwise add the pre-emulsion to initiate emulsion polymerization; and S3: After the emulsion polymerization is completed, add the post-elimination agent and neutralizing agent in sequence, adjust the solid content and filter to obtain the polymer emulsion; Preferably, the initiator is selected from one or more of ammonium persulfate, potassium persulfate, and sodium persulfate; the post-elimination agent is selected from a redox system, wherein the oxidant is tert-butyl hydroperoxide and the reducing agent is isoascorbic acid; the neutralizing agent is selected from one or more of ammonia, ethanolamine, and N,N-dimethylethanolamine. Preferably, in step S1, the emulsifier used to prepare the preemulsion includes the sulfosuccinate emulsifier; Preferably, in step S2, the pre-emulsion is added dropwise over 2 to 6 hours, and the temperature is maintained for another 0.5 to 2 hours after the addition is completed. Preferably, in step S3, after the emulsion polymerization is completed, the temperature is lowered to 65-75°C, a post-elimination agent is added and the temperature is maintained for 0.5-2 hours, then the temperature is lowered to below 45°C, a neutralizing agent is added to adjust the pH value to 7-9, the solid content is adjusted and filtered to obtain the polymer emulsion.

9. Use of the polymer emulsion according to any one of claims 1-7 in the preparation of coatings; Preferably, the coating is a water-based coating, and more preferably, a wood coating.

10. A coating prepared from the polymer emulsion according to any one of claims 1-7; Preferably, the coating is a water-based coating, and more preferably, a wood coating.

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