A high-temperature stable interior wall coating with zero SVOC emissions and its preparation method

Abstract

This invention relates to a zero-SVOC emission, high-temperature stable interior wall coating and its preparation method, belonging to the field of architectural coatings technology. The coating is composed of a specific core-shell structured styrene-acrylic emulsion, a combination of flake silicate fillers (mica powder and low-temperature calcined kaolin), titanium dioxide, 700-mesh calcium carbonate, water, and additives in a specific ratio, and contains no film-forming aids. The shell layer of the core-shell emulsion has a glass transition temperature of 0–10°C, a crosslinking density of 0.5%–1.5%, and contains hydrophobic functional monomers. This invention solves the contradiction between the easy drying of the coating film on the barrel wall during high-temperature storage and the need to add film-forming aids during low-temperature construction through a triple synergy of "core-shell crosslinking + hydrophobic modification + flake barrier". After 30 days of heat storage at 50°C, the coating film on the barrel wall remains moist without a film layer; it forms a normal film at 5°C; VOC < 2g / L; SVOC < 0.1g / L; fast surface drying; and excellent overall performance, meeting the latest environmental standards for coatings.

Description

Technical Field

[0001] This invention relates to the field of architectural coatings technology, specifically to a high-temperature stable interior wall coating with zero SVOC emissions and its preparation method. Background Technology

[0002] Water-based interior wall coatings have been widely used in the building decoration field due to their advantages such as environmental friendliness and ease of application. However, in actual use and storage, two technical contradictions have long existed that are difficult to reconcile: First, the problem of "drying and sticking" during high-temperature storage in summer: During the hot summer months, paint is exposed to high temperatures (35-50°C) for extended periods in warehouses or during transportation. The shaking of paint buckets during handling causes paint to adhere to the inner wall of the lid and the upper vapor space of the bucket. In these areas, the paint quickly dries and peels due to continuous moisture evaporation. When users open the lid and stir, this dried film mixes into the paint, resulting in particles and pitting on the coating surface, severely affecting the coating effect. This problem is common in both iron and plastic drum packaging.

[0003] Second, the issue of "dependence on film-forming aids" during low-temperature construction in winter: Traditional acrylic emulsions typically have a high minimum film-forming temperature (MFFT) (20–30°C). When applying at low temperatures (5–10°C), a certain amount of film-forming aids (such as Texanol, DPnB, benzyl alcohol, etc.) needs to be added to lower the MFFT and achieve normal film formation. However, most of these film-forming aids fall into the VOC or SVOC category, which not only increases the VOC / SVOC content of the coating but also leads to prolonged surface drying time and decreased early water resistance.

[0004] The existing technologies for solving the above problems have obvious flaws: (1) The water retention is improved by adding a large amount of high-boiling-point solvents (ethylene glycol, propylene glycol, etc.) to delay the skin formation, but these substances are mostly VOCs or SVOCs and will significantly prolong the surface drying time.

[0005] (2) There have been reports on the use of core-shell emulsions to reduce the amount of film-forming aids. However, the shell of existing core-shell emulsions is mostly a soft shell with extremely low Tg (<-10℃), which is easy to soften and stick in high temperature environment. The coating on the wall quickly melts into a skin and has poor high temperature anti-skinning performance.

[0006] (3) There are also reports on the technology of using crosslinking monomers to improve the heat resistance of emulsions, but excessive crosslinking will lead to a significant increase in the minimum film-forming temperature, making it impossible to achieve low-temperature zero SVOC film formation. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention aims to provide a high-temperature stable interior wall coating with zero SVOC emissions and its preparation method. This invention resolves the contradiction between the tendency of building coatings to dry and clump on the barrel wall during high-temperature storage and the need to add film-forming aids during low-temperature construction, which leads to excessive SVOC levels. This invention exhibits excellent anti-drying performance during high-temperature storage and can form a normal film without the need for film-forming aids during low-temperature (≥5℃) construction.

[0008] The first objective of this invention is: A high-temperature stable interior wall coating with zero SVOC emissions is provided, comprising the following raw material components in parts by weight: The composition consists of 35-55 parts of core-shell structured styrene-acrylic emulsion, 5-15 parts of flake silicate filler, 15-25 parts of titanium dioxide, 5-15 parts of 700-mesh heavy calcium carbonate, 8-25 parts of water, and 0.5-3.5 parts of additives. The latex particles of the core-shell structured styrene-acrylic emulsion include a core layer and a shell layer covering the core layer; The core layer is a hard core composed of linear polymer chain monomers, with a glass transition temperature of 30–50°C. The linear polymer chain monomers include styrene, methyl methacrylate, butyl acrylate and methacrylic acid, and the core layer does not contain crosslinking monomers and hydrophobic functional monomers; The shell is a soft shell with a cross-linked network structure, a glass transition temperature of 0 to 10°C, a cross-linking density of 0.5% to 1.5%, and the constituent monomers of the shell include cross-linked monomers and hydrophobic functional monomers. The mass ratio of the core layer to the shell layer is 1:1 to 1.5; The sheet-like silicate filler assembly includes mica powder with a diameter-to-thickness ratio ≥ 50 and low-temperature calcined kaolin at a calcination temperature of 700–800℃. The additives include dispersants, wetting agents, defoamers, thickeners, pH adjusters, and preservatives; Furthermore, the coating does not contain any film-forming aids.

[0009] The zero-SVOC emission high-temperature stable interior wall coating of this invention is further optimized as follows: The mica powder is sericite, and its addition amount is 3 to 8 parts, with an aspect ratio ≥80, preferably ≥100; The amount of the low-temperature calcined kaolin added is 3 to 8 parts; preferably, the whiteness is ≥90% and the average particle size is ≤2μm, so as to further improve the barrier performance and coating whiteness. The mass ratio of the mica powder to the low-temperature calcined kaolin is 1:0.5 to 2.

[0010] The zero-SVOC emission high-temperature stable interior wall coating of this invention is further optimized as follows: The hydrophobic functional monomer is selected from one or a combination of organosilicon monomers, fluorine-containing monomers, or long-chain alkyl monomers.

[0011] The zero-SVOC emission high-temperature stable interior wall coating of this invention is further optimized as follows: The hydrophobic functional monomer is selected from one or a combination of vinyl-terminated polydimethylsiloxane, vinyldimethylsiloxane, dodecyl fluoroheptyl methacrylate, octadecyl methacrylate, octafluoropentyl acrylate, hexafluorobutyl acrylate, trifluoroethyl methacrylate, hexafluoroisopropyl methacrylate, hexafluorobutyl methacrylate, dodecyl acrylate, and vinyltrimethoxysilane.

[0012] The zero-SVOC emission high-temperature stable interior wall coating of this invention is further optimized as follows: The hydrophobic functional monomer is a vinyl-terminated polydimethylsiloxane with an average molecular weight of 1000-5000, and the amount added is 0.5%-5% of the total mass of the shell monomer.

[0013] The zero-SVOC emission high-temperature stable interior wall coating of this invention is further optimized as follows: The crosslinking density of the shell layer is 0.5% to 1.5%; The crosslinking monomer in the shell is divinylbenzene or ethylene glycol dimethacrylate, and the amount added is 0.5% to 1.5% of the total mass of the shell monomers.

[0014] The zero-SVOC emission high-temperature stable interior wall coating of this invention is further optimized as follows: The pH adjuster is butyl diethanolamine.

[0015] The zero-SVOC emission high-temperature stable interior wall coating of this invention is further optimized as follows: The thickener is selected from one or a combination of hydrophobically modified alkali-swellable thickeners, associative polyurethane thickeners, and cellulose thickeners.

[0016] The zero-SVOC emission high-temperature stable interior wall coating of this invention is further optimized as follows: The preparation method of the core-shell structured styrene-acrylic emulsion includes the following steps: s1. Seed emulsion preparation: Water, emulsifier (sodium dodecyl sulfate) and buffer (sodium bicarbonate) are added to the reaction vessel, the temperature is raised to 75-80℃, a portion of the core layer monomer (accounting for 5%-15% of the total weight of monomer) and the first part of initiator (10% of the total amount of initiator) are added and the reaction is carried out for 20-40 minutes to form a seed emulsion; s2. Core layer polymerization: At 75-85°C, the remaining core layer monomer and the second part of initiator (40% of the total initiator amount) are added dropwise to the seed emulsion to carry out the polymerization reaction (dropwise addition for 1.5-2.5 hours, followed by heat preservation for 0.5-1 hour). s3. Shell polymerization: Cool the reaction system to 70-75°C, and add shell monomers including crosslinking monomers (such as ethylene glycol dimethacrylate) and hydrophobic functional monomers, as well as a third initiator (50% of the total initiator amount) dropwise to carry out the polymerization reaction (dropwise addition for 3-4 hours, keeping the dropping rate lower than the polymerization rate of the monomers under the reaction conditions to ensure that there is no significant accumulation of free monomers in the reaction system). s4. Post-processing: Keep warm for 1-2 hours, cool down, adjust pH to 7.5-8.5, filter, and obtain the core-shell structured styrene-acrylic emulsion; in: The first, second, and third portions all contain water-soluble persulfate initiators (such as potassium persulfate or ammonium persulfate). In step s2, the core polymerization temperature is 5 to 10°C higher than the shell polymerization temperature in step s3.

[0017] The second objective of this invention is: A method for preparing the aforementioned zero-SVOC emission high-temperature stable interior wall coating is provided, comprising the following steps: S1. Disperse water, thickener, and pH adjuster at 300-500 rpm for 2-3 minutes. Then add dispersant, wetting agent, and part of the defoamer (e.g., half the total amount of defoamer) and disperse at 300-500 rpm for 2-3 minutes. Add titanium dioxide, mica powder, low-temperature calcined kaolin, and 700-mesh heavy calcium carbonate at 600-700 rpm and disperse at high speed until the fineness is ≤50μm to obtain pigment and filler slurry. S2. Add the core-shell structured styrene-acrylic emulsion, the remaining defoamer, and the preservative to the pigment and filler slurry obtained in step S1 at a speed of 600-700 rpm, and mix evenly; S3. Add a hydrophobic modified polyether thickener to adjust the coating viscosity to 98-102 KU, and prepare the high-temperature stable building interior wall coating with zero SVOC emission.

[0018] The preparation method of the zero SVOC emission high-temperature stable interior wall coating of the present invention is further optimized as follows: The high-speed dispersion in step S1 is performed at a rotation speed of 1400-1600 rpm for 14-16 minutes.

[0019] The performance of the zero SVOC emission high-temperature stable interior wall coating of this invention meets the following requirements: a. After being stored at a constant temperature of 50℃ for 30 days, the coating adhering to the vapor phase zone of the inner wall of the barrel showed no visible cracks or powdering and remained moist. b. After drying for 24 hours at 5℃±2℃, wind speed 1m / s, and relative humidity 50%±5%, the coating film is continuous and without cracks; c. Surface drying time ≤ 45 minutes; d. Volatile organic compound content < 2 g / L, semi-volatile organic compound content < 0.1 g / L; e. Washability > 10,000 cycles, contrast ratio ≥ 0.95.

[0020] Compared with the prior art, the present invention has the following technical features and technical effects: (I) A triple synergistic mechanism achieves excellent high-temperature anti-wall adhesion and anti-drying performance: This invention solves the problem of high-temperature wall adhesion and drying through a triple synergistic mechanism of "core-shell crosslinking + hydrophobic modification + sheet-like barrier". (1) Crosslinking network mechanism: The moderately crosslinked network of the shell (crosslinking density 0.5% to 1.5%) restricts the thermal motion of polymer chains at high temperatures, keeping the latex particles in a quasi-solid state and preventing the wet film adhering to the barrel wall from softening and fusing into a skin. Experiments show that the anti-skinning effect decreases significantly when the crosslinking density is below 0.5%, and affects low-temperature film formation when it is above 1.5%. 0.5% to 1.5% is a verified critical selection range.

[0021] (2) Hydrophobic modification mechanism: The introduction of hydrophobic functional monomers (such as vinyl-terminated polydimethylsiloxane, Vi-PDMS) significantly reduces the surface energy of the coating (from about 40 mN / m to ≤25 mN / m), causing the wall-mounted droplets to shrink into spherical shapes, significantly reducing the amount of coating and the contact area with air. Contact angle tests show that the contact angle of the modified coating with the plastic bucket wall increases (from 70-80° to 95-105°).

[0022] (3) Sheet-like barrier mechanism: Mica powder (diameter-to-thickness ratio ≥50) and low-temperature calcined kaolin form a parallel physical barrier layer on the wet film surface, like a "tile" covering, effectively blocking oxygen penetration and delaying moisture evaporation and oxidative drying.

[0023] The synergistic effect of the above three mechanisms ensures that the coating of this invention remains moist on the lid and barrel wall after being stored at 50°C for 30 days, with no visible dried film. It can be applied directly after opening the can without filtration, while commercially available ordinary coatings will show serious film formation under the same conditions.

[0024] (II) Moderate crosslinking achieves low-temperature zero SVOC film formation and excellent environmental friendliness: Unlike traditional methods that rely on excessive crosslinking to prevent film formation, this invention precisely controls the crosslinking density of the shell layer within a "moderate" range of 0.5% to 1.5%. This ensures that the capillary pressure during the coating drying process is sufficient to overcome crosslinking resistance, driving the polymer chains in the shell layer to permeate and fuse with each other. This allows for complete film formation at temperatures above 5°C without the need for any film-forming aids. The resulting coating exhibits a VOC content of <2 g / L and an SVOC content of <0.1 g / L, fully meeting the requirements of GB / T 9755-2024 and GB 30981.1-2025 standards for superior-grade interior wall paints, achieving zero SVOC emissions.

[0025] (iii) Fast surface drying speed and good construction performance: Because it completely eliminates high-boiling-point film-forming aids, the surface drying time of the coating of this invention is ≤45 minutes (23℃, 50%RH), which is far superior to the comparative sample with added film-forming aids, thus avoiding the traditional defect of sacrificing drying speed for water retention and anti-skinning.

[0026] (iv) Excellent overall performance: The coating of this invention has a washability of >10,000 cycles and a contrast ratio of ≥0.95, and can be widely used in interior wall decoration of buildings. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and comparative experiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Unless otherwise specified, the reagents, equipment, and methods used in this invention are conventional reagents, equipment, and general methods in this technical field.

[0028] Example 1: Preparation of core-shell structured styrene-acrylic emulsion This embodiment prepares a core-shell structured styrene-acrylic emulsion for the coating described above, comprising the following preparation steps: s1. Seed emulsion preparation: Add 200g of deionized water, 0.75g of emulsifier (sodium dodecyl sulfate), and 0.3g of buffer (sodium bicarbonate) to a 1000ml four-necked flask. Start stirring (300rpm) and heat to 78℃. After the system is evenly dissolved, add 10% (10g) of the core layer monomer mixture (styrene, methyl methacrylate, butyl acrylate) as seed monomer, and add the first initiator solution (containing 0.1g of potassium persulfate dissolved in 5g of deionized water). React for 30 minutes. The system shows a distinct blue opalescence, indicating that the seed emulsion has formed. s2. Core layer polymerization: Maintain the temperature at 80±2℃, and add the remaining core layer monomer (36g) and the second part of the initiator solution (containing 0.4g of potassium persulfate dissolved in 20g of deionized water) dropwise to the seed emulsion; control the dropping rate so that the monomer is added completely within 2 hours; after the dropping is completed, continue to keep warm at 80℃ for 1 hour to allow the core layer monomer to fully polymerize; s3. Shell polymerization: The reaction system is cooled to 73°C, and the shell monomer mixture and the third initiator solution are added dropwise. The shell monomer mixture includes: 52g of methyl methacrylate, 45g of butyl acrylate, 1.0g of crosslinking monomer ethylene glycol dimethacrylate, and 2.0g of hydrophobic functional monomer terminal vinyl polydimethylsiloxane (Vi-PDMS, Mn=2000); The third initiator solution contains 0.5g of potassium persulfate (dissolved in 25g of deionized water); Control the dropping rate to ensure that the monomer is added within 3.5 hours, and keep the dropping rate of the reaction system lower than the polymerization rate of the monomer under the reaction conditions to ensure that there is no significant accumulation of free monomer in the reaction system (free monomer concentration in the system < 0.5%). After the addition is complete, keep warm at 73℃ for 1.5 hours; S4. Post-treatment: Cool the reaction system to below 40°C, adjust the pH of the emulsion to 8.0-8.5 with an appropriate amount of butyl diethanolamine; finally filter with a 200-mesh filter cloth to obtain a core-shell structured styrene-acrylic emulsion with a solid content of about 40%.

[0029] Tests showed that the glass transition temperature (Tg) of the emulsion shell was approximately 5°C. Calculations indicated that the shell crosslinking density was approximately 1.0% (based on the crosslinking monomers as a percentage of the total shell monomer mass).

[0030] Example 2: Preparation of Zero SVOC Emission High-Temperature Stable Interior Wall Coating This embodiment prepares a high-temperature stable building interior wall coating with zero SVOC emissions. The specific raw material composition is shown in Table 1.

[0031] Table 1. Raw material composition (parts by weight) for Example 2

[0032] The zero-SVOC emission high-temperature stable interior wall coating includes the following preparation steps: S1. Disperse water, cellulose thickener, and butyl diethanolamine (pH adjuster) at 300-500 rpm for 2-3 min. Add dispersant, wetting agent, and half of the defoamer (1 / 2 of the total amount of defoamer) and disperse at 300-500 rpm for 2-3 min. Add titanium dioxide, mica powder, low-temperature calcined kaolin, and 700 mesh heavy calcium carbonate at 600-700 rpm. Disperse at 1450-1550 rpm for 14-16 min until the fineness is ≤50 μm to obtain pigment and filler slurry. S2. Add the core-shell structured styrene-acrylic emulsion, the remaining defoamer, and the preservative to the pigment and filler slurry obtained in step S1 at a speed of 600-700 rpm, and mix evenly; S3. Add hydrophobic modified polyether thickener to adjust the coating viscosity to 98-102 KU.

[0033] Comparative Example 1 (Ordinary Interior Wall Paint) The only difference between this comparative example and Example 2 is that: The emulsion used is a common commercially available single-layer styrene-acrylic emulsion (Tg=15℃, no cross-linking structure, no hydrophobic modification).

[0034] To enable film formation at a low temperature of 5°C, an additional 2% (by weight of the total coating mass) of film-forming aid (Texanol) was added. All other raw materials, dosages, and preparation steps were identical to those in Example 2.

[0035] Performance testing and results analysis: The coatings obtained in Example 2 and Comparative Example 1 were subjected to performance tests, and the test results are shown in Table 2.

[0036] Table 2. Coating performance test results

[0037] Results analysis: As shown in Table 2, the coating prepared in Example 2 of this invention, without the addition of any film-forming aids, successfully achieved a perfect balance between high-temperature storage anti-skinning (no skinning for 30 days at 50℃) and normal film formation during low-temperature construction (continuous film formation at 5℃). Furthermore, it exhibits extremely low VOC and SVOC content, rapid surface drying, and excellent overall physical properties, comprehensively exceeding the requirements of the national standard for superior-grade products. In contrast, Comparative Example 1, using ordinary emulsion, could not form a film at low temperatures without the addition of film-forming aids; adding film-forming aids to meet low-temperature construction requirements resulted in severely excessive SVOC levels, prominent skinning problems during high-temperature storage, and a significantly prolonged surface drying time.

[0038] Comparative Example 2 The main difference between Comparative Example 2 and Example 2 is that Comparative Example 2 uses a core-shell emulsion with a shell crosslinking density of 0.3% (reducing ethylene glycol dimethacrylate to 0.3g), while the rest is the same as in Example 1.

[0039] Test results: After 30 days of heat storage at 50℃, slight crusting appeared on the barrel wall, which does not meet the requirements.

[0040] Comparative Example 3 The main difference between Comparative Example 3 and Example 2 is that Comparative Example 3 uses a core-shell emulsion with a shell crosslinking density of 1.8% (by increasing ethylene glycol dimethacrylate to 1.8g), while the rest is the same as in Example 1.

[0041] Test results: The surface drying time of the paint film at 5℃ exceeded 2 hours, and film formation was not possible.

[0042] This verifies that the crosslinking density of 0.5% to 1.5% selected in this invention is the key range for achieving the balance between "anti-skinning + low-temperature film formation".

[0043] The above test results and comparisons fully demonstrate that the present invention, through the overall technical solution of "a core-shell emulsion with a specific structure + a combination of sheet-like fillers + zero film-forming aids", has produced unexpected synergistic technical effects.

[0044] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-temperature stable interior wall coating with zero SVOC emissions, characterized in that: The raw material components include the following parts by weight: The composition consists of 35-55 parts of core-shell structured styrene-acrylic emulsion, 5-15 parts of flake silicate filler, 15-25 parts of titanium dioxide, 5-15 parts of 700-mesh heavy calcium carbonate, 8-25 parts of water, and 0.5-3.5 parts of additives. The latex particles of the core-shell structured styrene-acrylic emulsion include a core layer and a shell layer covering the core layer; The core layer is a hard core composed of linear polymer chain monomers, with a glass transition temperature of 30–50°C. The linear polymer chain monomers include styrene, methyl methacrylate, butyl acrylate, and methacrylic acid; The shell is a soft shell with a cross-linked network structure, a glass transition temperature of 0 to 10°C, a cross-linking density of 0.5% to 1.5%, and the constituent monomers of the shell include cross-linked monomers and hydrophobic functional monomers. The mass ratio of the core layer to the shell layer is 1:1 to 1.5; The sheet-like silicate filler assembly includes mica powder with a diameter-to-thickness ratio ≥ 50 and low-temperature calcined kaolin at a calcination temperature of 700–800℃. The additives include dispersants, wetting agents, defoamers, thickeners, pH adjusters, and preservatives.

2. The high-temperature stable interior wall coating with zero SVOC emissions according to claim 1, characterized in that: The mica powder is sericite, and its addition amount is 3 to 8 parts with an aspect ratio ≥ 80. The amount of the low-temperature calcined kaolin added is 3 to 8 parts, and optionally: whiteness ≥90%, average particle size ≤2μm; The mass ratio of the mica powder to the low-temperature calcined kaolin is 1:0.5 to 2.

3. The high-temperature stable interior wall coating with zero SVOC emissions according to claim 1, characterized in that: The hydrophobic functional monomer is selected from one or a combination of organosilicon monomers, fluorine-containing monomers, or long-chain alkyl monomers.

4. The high-temperature stable interior wall coating with zero SVOC emissions according to claim 3, characterized in that: The hydrophobic functional monomer is selected from one or a combination of vinyl-terminated polydimethylsiloxane, vinyldimethylsiloxane, dodecyl fluoroheptyl methacrylate, octadecyl methacrylate, octafluoropentyl acrylate, hexafluorobutyl acrylate, trifluoroethyl methacrylate, hexafluoroisopropyl methacrylate, hexafluorobutyl methacrylate, dodecyl acrylate, and vinyltrimethoxysilane.

5. The high-temperature stable interior wall coating with zero SVOC emissions according to claim 4, characterized in that: The hydrophobic functional monomer is vinyl-terminated polydimethylsiloxane with an average molecular weight of 1000-5000, and the amount added is 0.5%-5% of the total mass of the shell monomer.

6. The high-temperature stable interior wall coating with zero SVOC emissions according to claim 1, characterized in that: The crosslinking density of the shell layer is 0.5% to 1.5%; The crosslinking monomer in the shell is divinylbenzene or ethylene glycol dimethacrylate, and the amount added is 0.5% to 1.5% of the total mass of the shell monomers.

7. The high-temperature stable interior wall coating with zero SVOC emissions according to claim 1, characterized in that: The pH adjuster is butyl diethanolamine.

8. The zero-SVOC emission high-temperature stable interior wall coating according to claim 1, characterized in that: The preparation method of the core-shell structured styrene-acrylic emulsion includes the following steps: s1. Seed emulsion preparation: Water, emulsifier and buffer are added to the reaction vessel, the temperature is raised to 75-80℃, a portion of the core layer monomer and the first initiator are added and reacted for 20-40 minutes to form a seed emulsion; s2. Core layer polymerization: At 75-85°C, the remaining core layer monomer and the second part of the initiator are added dropwise to the seed emulsion to carry out the polymerization reaction; s3. Shell polymerization: Cool the reaction system to 70-75°C, add shell monomers including crosslinking monomers and hydrophobic functional monomers and a third initiator dropwise to carry out the polymerization reaction; s4. Post-processing: Keep warm for 1-2 hours, cool down, adjust pH to 7.5-8.5, filter, and obtain the core-shell structured styrene-acrylic emulsion; in: The first, second, and third portions all contained water-soluble persulfate initiators. In step s2, the core polymerization temperature is 5 to 10°C higher than the shell polymerization temperature in step s3.

9. A method for preparing a high-temperature stable interior wall coating with zero SVOC emissions as described in any one of claims 1 to 8, characterized in that: Includes the following steps: S1. Disperse water, thickener, and pH adjuster at 300-500 rpm for 2-3 minutes, then add dispersant, wetting agent, and part of defoamer and disperse at 300-500 rpm for 2-3 minutes to mix; add titanium dioxide, mica powder, low-temperature calcined kaolin, and 700-mesh heavy calcium carbonate at 600-700 rpm and disperse at high speed until the fineness is ≤50μm to obtain pigment and filler slurry; S2. Add the core-shell structured styrene-acrylic emulsion, the remaining defoamer, and the preservative to the pigment and filler slurry obtained in step S1 at a speed of 600-700 rpm, and mix evenly; S3. Add a hydrophobic modified polyether thickener to adjust the coating viscosity to 98-102 KU, and prepare the high-temperature stable building interior wall coating with zero SVOC emission.

10. The method for preparing a high-temperature stable interior wall coating with zero SVOC emissions according to claim 9, characterized in that: The high-speed dispersion in step S1 is performed at a rotation speed of 1400-1600 rpm for 14-16 minutes.

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