A core-shell acetate emulsion for interior walls and its preparation method

Abstract

This invention belongs to the field of polymer material synthesis technology, specifically relating to a core-shell vinyl acetate emulsion for interior walls and its preparation method. Addressing the problems of insufficient scrub resistance and low efficiency in introducing functional monomers in existing vinyl acetate emulsions, the following solution is provided: A pre-emulsion A is obtained by emulsifying deionized water, a composite emulsifier, and a pH buffer with a core-layer mixed monomer mixture. The core-layer mixed monomer mixture includes vinyl acetate, vinyl tert-carbonate, C1-C4 alkyl esters of (meth)acrylate, a carboxylic acid functional monomer containing double bonds, diacetone acrylamide, and organosilicon-modified monomers. After seed emulsion preparation and core-layer polymerization, a shell-layer monomer mixture B (containing phosphate-based adhesion-promoting monomers, hydroxyalkyl esters, and vinyl acetate) is introduced for shell-layer polymerization. Post-treatment yields the emulsion. The emulsion possesses a hard core-functionalized soft shell structure, and the resulting interior wall coating can withstand over 8000 scrub cycles, far exceeding the national standard for superior products. Furthermore, the emulsion exhibits excellent storage stability.

Description

Technical Field

[0001] This invention relates to the field of polymer material synthesis technology, specifically to a core-shell acetate emulsion for interior walls and its preparation method. Background Technology

[0002] Water-based vinyl acetate emulsions are widely used in interior wall coatings due to their excellent water resistance, alkali resistance, anti-tack properties, and high cost-effectiveness. Traditional vinyl acetate emulsions are typically prepared using vinyl acetate (VAc) and vinyl tert-carbonate (VeoVa10, etc.) as the main comonomers through emulsion polymerization.

[0003] However, with the increasing demands on the performance of interior wall coatings, especially the increasing requirements for scrub resistance (the national standard GB / T 9756-2018 requires a scrub resistance of more than 6000 times for superior products), stain resistance and storage stability, traditional acetic acid emulsions have the following shortcomings: (1) Scrub resistance needs to be improved. The scrub resistance of conventional acetic acid emulsions is usually between 2000 and 5000 times, which is difficult to stably meet the requirements for superior products; (2) The efficiency of introducing functional monomers is low. The functional monomers introduced to improve adhesion and crosslinking density decrease in activity in the later stage of polymerization, resulting in uneven distribution in the polymer chain and difficulty in fully exerting their performance; (3) It is difficult to balance the rigidity and flexibility of the paint film. While pursuing a lower minimum film-forming temperature (MFFT), conventional emulsions result in insufficient paint film strength, which affects scrub resistance.

[0004] Therefore, developing an acetate emulsion with higher scrub resistance, good film flexibility, and excellent storage stability is of great significance for promoting the development of high-performance environmentally friendly interior wall coatings. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing a core-shell acetate emulsion for interior walls. This method, through innovative monomer combination, emulsion system design, and core-shell polymerization process control, prepares an acetate emulsion with a core-shell structure, high crosslinking density, and a gradient distribution of functional monomers.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The first aspect of this invention discloses a method for preparing a core-shell acetate emulsion for interior walls, comprising the following steps:

[0008] (1) Preparation of pre-emulsion A: Deionized water, composite emulsifier and pH buffer are mixed evenly, and core layer mixed monomer is added under stirring. The mixture is emulsified evenly to obtain pre-emulsion A. The core layer mixed monomer is composed of the following monomers in parts by weight: 50-70 parts of vinyl acetate, 25-40 parts of ethylene tert-carbonate, 3-10 parts of (meth)acrylate C1-C4 alkyl ester, 1-3 parts of carboxylic acid functional monomer containing double bond, 0.5-2 parts of diacetone acrylamide and 0.5-2 parts of organosilicon modified monomer.

[0009] (2) Preparation of seed emulsion: Add 25%-45% of deionized water, 0-40% of composite emulsifier and pH buffer to the reaction vessel, heat to 75-80℃, add 10-20% of initiator solution, keep warm for 10 minutes, then add 10-15% of pre-emulsion A and 20-30% of initiator solution to the reaction vessel simultaneously over 1-1.5 hours, keep warm for 30 minutes to obtain seed emulsion;

[0010] (3) Core layer polymerization: The remaining pre-emulsion A and the initiator solution are simultaneously added dropwise to the seed emulsion at 78-82℃, and the addition is completed within 2.5-3.5 hours. The mixture is kept warm for 30 minutes.

[0011] (4) Shell polymerization: The shell monomer mixture B is added dropwise to the core polymerization product over 0.5-1 hour. The shell monomer mixture B comprises, by weight, 2-5 parts of (meth)acrylate hydroxyalkyl ester, 0.5-1.5 parts of (meth)acrylate adhesion promoter monomer with phosphate ester groups directly bonded to the 2-3 carbon hydroxyl side chains, and 4-10 parts of vinyl acetate.

[0012] (5) Post-treatment: Heat to 85-88℃ and keep warm for 1 hour, cool down to below 60℃ and add redox post-elimination agent, adjust pH to 7.5-8.5, filter and discharge to obtain the core shell acetic acid tert-emulsion for interior walls.

[0013] Optionally, in step (1), the composite emulsifier is a mixture of anionic emulsifier and nonionic emulsifier in a mass ratio of 1.5:1 to 2.5:1, and the total amount used accounts for 1.5%-3.0% of the total mass of the core-layer mixed monomers; the anionic emulsifier is selected from one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate or sodium allyloxyhydroxypropyl sulfonate; the nonionic emulsifier is selected from one or more of alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether or isomeric tridecyl alcohol polyoxyethylene ether.

[0014] Optionally, in step (1), the (meth)acrylic acid C1-C4 alkyl ester is methyl methacrylate; the organosilicon-modified monomer in step (1) is one of vinyltrimethoxysilane or γ-(methacryloyloxy)propyltrimethoxysilane; the carboxylic acid functional monomer containing double bonds in step (1) is one or more of acrylic acid, methacrylic acid or itaconic acid.

[0015] Optionally, the molecular weight of the (meth)acrylate adhesion promoter monomer in step (4) whose phosphate group is directly bonded to the 2-3 carbon hydroxyl side chain is ≤400, is one or more of hydroxyethyl methacrylate phosphate monoester, hydroxyethyl methacrylate phosphate dieester, or hydroxypropyl methacrylate phosphate.

[0016] Optionally, the hydroxyalkyl methacrylate mentioned in step (4) is one or both of hydroxyethyl acrylate or hydroxypropyl methacrylate.

[0017] Optionally, the initiator is an aqueous solution of ammonium persulfate or potassium persulfate, and its total amount accounts for 0.4%-1.0% of the total mass of the monomer.

[0018] A second aspect of this invention discloses a core-shell acetate emulsion for interior walls, the emulsion having a core-shell structure:

[0019] The core layer is copolymerized from the following monomers in parts by weight: 50-70 parts vinyl acetate, 25-40 parts ethylene tert-carbonate, 3-10 parts C1-C4 alkyl methacrylate, 1-3 parts carboxylic acid functional monomers containing double bonds, 0.5-2 parts diacetone acrylamide, and 0.5-2 parts organosilicon modified monomers.

[0020] The shell is copolymerized from the following monomers in parts by weight: 2-5 parts of hydroxyalkyl methacrylate, 0.5-1.5 parts of methacrylate adhesion promoter monomers with phosphate groups directly bonded to the 2-3 carbon hydroxyl side chains, and 4-10 parts of vinyl acetate.

[0021] In the core layer, diacetone acrylamide is bonded to the polymer chain in the form of amide groups, which is used to undergo a ketone-hydrazide crosslinking reaction with adipic acid dihydrazide.

[0022] Optionally, the emulsion has a solid content of 48%-52%, a pH of 7.5-8.5, and a latex particle size of 80-200 nm.

[0023] A third aspect of this invention discloses an interior wall latex paint, comprising, by weight:

[0024] 200-350 parts of the core-shell acetic acid tert-emulsion for interior walls as described in the second aspect of this invention;

[0025] 150-250 parts of rutile titanium dioxide;

[0026] 150-300 parts of filler;

[0027] 5-10 parts of dispersant;

[0028] 8-15 parts of film-forming aid;

[0029] Thickener 2-5 parts;

[0030] 1-8 parts of adipic acid dihydrazide;

[0031] Add an appropriate amount of deionized water to 1000 parts;

[0032] The molar ratio of the adipic acid dihydrazide to the diacetone acrylamide in the acetic acid emulsion is 0.8:1 to 1.2:1.

[0033] Optionally, the filler is one or two of heavy calcium carbonate and calcined kaolin.

[0034] The present invention has the following beneficial effects:

[0035] (1) Significantly improved scrub resistance: Through the “hard core-functionalized soft shell” structural design, the core layer provides rigid support, and the shell layer introduces functional groups such as hydroxyl and phosphate groups to enhance adhesion and cross-linking potential. Combined with the later ketone-hydrazine cross-linking system, the paint film is dense and tough, and the number of scrub resistance can reach more than 8,000 times, far exceeding the requirements of the national standard GB / T 9756-2018 for superior products (6,000 times).

[0036] (2) Balanced and excellent performance: The introduction of organosilicon modified monomers improves the hydrophobicity and stain resistance of the coating film without significantly increasing MFFT, ensuring good low-temperature construction film formation; the gradient core-shell polymerization process makes the functional monomer distribution more reasonable, taking into account both hardness and flexibility.

[0037] (3) Good storage stability: The optimized composite emulsion system and polymerization process make the latex particles uniform in size and narrow in distribution, and the emulsion has excellent mechanical stability, chemical stability and freeze-thaw stability.

[0038] (4) Environmental protection and high cost performance: The main monomer is VAC with low price, which effectively controls the cost of raw materials while ensuring high performance; the system does not contain formaldehyde-releasing additives, which meets the requirements of green environmental protection. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments. In the following embodiments, the amounts of each raw material are by weight; the emulsions obtained in each embodiment are formulated into interior wall latex paints according to the same basic formula (pigment volume concentration of PVC is about 45%), and performance tests are conducted according to national standards such as GB / T 9756-2018. However, the scope of protection of the present invention is not limited to the following embodiments.

[0040] Example 1 (E1)

[0041] The raw material composition of a core-shell acetate emulsion for interior walls is shown in Table 1 (core layer) and Table 2 (shell layer), and its specific preparation steps are as follows:

[0042] Table 1. Composition of Core Layer Pre-emulsion A in Example 1

[0043] Components Dosage (parts by weight) Vinyl acetate (VAc) 60 Ethylene tert-carbonate (VeoVa 10) 30 Methyl methacrylate (MMA) 6 Acrylic acid (AA) 1.5 Diacetone Acrylamide (DAAM) 1.2 Vinyltrimethoxysilane (VTMS) 0.8 Sodium allyl hydroxypropyl sulfonate (COPS-1, anionic) 1.5 Isomeric tridecyl alcohol polyoxyethylene ether (nonionic) 0.8 Sodium bicarbonate (pH buffer) 0.3

[0044] Table 2 Composition of Shell Monomer Mixture B in Example 1

[0045] Components Dosage (parts by weight) Hydroxyethyl acrylate (HEA) 3 Sipomer PAM-200 (Phosphate functional monomer) 1 Vinyl acetate (VAc) 6

[0046] The composition of the bottom liquid of the reaction vessel is as follows: 50 parts deionized water, 0.5 parts sodium allyl hydroxypropyl sulfonate (COPS-1), 0.2 parts nonionic emulsifier, 0.2 parts sodium bicarbonate; 1 part ammonium persulfate (APS) (added in three stages: initial, seed, and core layers); post-treatment raw materials such as film-forming aids are described in step 5.

[0047] Step 1, Pre-emulsification: Add 80 parts of deionized water, 1.5 parts of COPS-1, 0.8 parts of nonionic emulsifier, and 0.3 parts of sodium bicarbonate to a pre-emulsification vessel. After stirring evenly, slowly add all the core layer pre-emulsification monomers and stir at high speed for 30 minutes to obtain a uniform and stable pre-emulsion A.

[0048] Step 2, Seed Preparation: Add 50 parts water, base emulsifier, and buffer to the reactor and heat to 78°C. Add an initial initiator solution containing 0.2 parts APS (dissolved in 10 parts water) and maintain the temperature for 10 minutes. Then, simultaneously add 15% of the total amount of pre-emulsion A and 0.3 parts APS solution (dissolved in 30 parts water), completing the addition over 1 hour, and maintain the temperature for 30 minutes.

[0049] Step 3, Core layer polymerization: The remaining 85% of pre-emulsion A and the remaining 0.5 parts of APS aqueous solution are simultaneously and uniformly added to the seed emulsion over 3 hours, with the temperature controlled at 80±2℃ and kept warm for 30 minutes.

[0050] Step 4, shell polymerization: Add shell monomer mixture B (3 parts HEA, 1 part PAM-200, 6 parts VAc, premixed evenly) dropwise over 1 hour.

[0051] Step 5, Post-treatment: Heat to 86℃ and hold for 1 hour. Cool to 55℃, add 0.2 parts tert-butyl hydroperoxide and 0.1 parts ascorbic acid for post-elimination. Cool to 40℃, adjust pH to 8.0 with ammonia water, filter through a 200-mesh sieve to obtain tert-butyl acetate emulsion E1 with a solid content of approximately 50±1%.

[0052] Example 2 (E2)

[0053] The raw material composition of a core-shell acetate emulsion for interior walls is shown in Table 3 (core layer) and Table 4 (shell layer), and its specific preparation steps are as follows:

[0054] Table 3 Composition of Core Layer Pre-emulsion A in Example 2

[0055] Components Dosage (parts by weight) Vinyl acetate (VAc) 68 Ethylene tert-carbonate (VeoVa 10) 22 Methyl methacrylate (MMA) 8 Acrylic acid (AA) 1.0 Diacetone Acrylamide (DAAM) 1.0 Vinyltrimethoxysilane (VTMS) 0.5 Sodium allyl hydroxypropyl sulfonate (COPS-1, anionic) 1.8 Alkylphenol polyoxyethylene ether (OP-10, nonionic) 0.9 Sodium bicarbonate (pH buffer) 0.4

[0056] Table 4. Composition of Shell Monomer Mixture B in Example 2

[0057] Components Dosage (parts by weight) Hydroxyethyl acrylate (HEA) 2.0 Sipomer PAM-100 (Phosphate functional monomer) 0.8 Vinyl acetate (VAc) 6.0

[0058] Step 1, Pre-emulsification: Add 80 parts of deionized water, 1.8 parts of COPS-1, 0.9 parts of nonionic emulsifier, and 0.4 parts of sodium bicarbonate to a pre-emulsification vessel. After stirring evenly, slowly add all the core layer pre-emulsification monomers and stir at high speed for 30 minutes to obtain a uniform and stable pre-emulsion A.

[0059] Step 2, Seed and Core Polymerization: Add 40 parts of water to the reactor and heat to 78°C. Add an initial initiator solution containing 0.1 parts of APS, and after holding at this temperature for 10 minutes, simultaneously add 15% preemulsion A and an initiator solution containing 0.15 parts of APS dropwise over 1 hour, and hold at this temperature for 30 minutes to form seeds. Subsequently, add the remaining 85% preemulsion A and the remaining 0.4 parts of APS solution dropwise simultaneously over 3 hours, maintaining the temperature at 79±1°C and holding for 30 minutes.

[0060] Step 3, shell polymerization: Add shell monomer mixture B (premixed evenly) dropwise over 40 minutes.

[0061] Step 4, Post-treatment: Heat to 85℃ and hold for 1 hour, then cool to 55℃. Add 0.15 parts of tert-butyl hydrogen peroxide and 0.08 parts of sodium formaldehyde sulfoxylate for post-elimination. Cool to 40℃, adjust pH to 8.2 with ammonia, and filter through a 200-mesh filter to obtain emulsion E2 with a solid content of approximately 50±1%.

[0062] Example 3 (E3)

[0063] The raw material composition of a core-shell acetate emulsion for interior walls is shown in Table 5 (core layer) and Table 6 (shell layer), and its specific preparation steps are as follows:

[0064] Table 5 Composition of Core Layer Pre-emulsion A in Example 3

[0065] Components Dosage (parts by weight) Vinyl acetate (VAc) 55 Ethylene tert-carbonate (VeoVa 10) 30 Methyl methacrylate (MMA) 12 Methacrylic acid (MAA) 1.5 Diacetone Acrylamide (DAAM) 1.8 Vinyltrimethoxysilane (VTMS) 1.0 Sodium dodecyl sulfate (SDS, anionic) 1.2 Isomeric tridecyl alcohol polyoxyethylene ether (EO-9, nonionic) 0.6 Sodium bicarbonate (pH buffer) 0.3

[0066] Table 6 Composition of Shell Monomer Mixture B in Example 3

[0067] Components Dosage (parts by weight) Hydroxypropyl methacrylate (HPMA) 4.0 Sipomer PAM-200 (Phosphate functional monomer) 1.2 Vinyl acetate (VAc) 4.0

[0068] Step 1, Pre-emulsification: Add 60 parts of deionized water, 1.2 parts of sodium dodecyl sulfate (SDS), 0.6 parts of isotridecyl alcohol polyoxyethylene ether (EO-9), and 0.3 parts of sodium bicarbonate to a pre-emulsification kettle. After stirring evenly, slowly add all the core layer pre-emulsification monomers and stir at high speed for 30 minutes to obtain a uniform and stable pre-emulsion A.

[0069] Step 2, Seed and Core Layer Polymerization: Add 40 parts of water to the reactor and heat to 80℃. Add an initial initiator solution containing 0.075 parts of KPS (dissolved in 10 parts of water), maintain the temperature for 10 minutes, and then simultaneously add 12% preemulsion A and an initiator solution containing 0.15 parts of KPS (dissolved in 10 parts of water). Seed preparation is completed in 1 hour. Subsequently, the remaining preemulsion A and the remaining 0.525 parts of KPS (dissolved in 25 parts of water) are added simultaneously over 3.5 hours, with the temperature strictly controlled at 81±1℃ and maintained for 30 minutes.

[0070] Step 3, shell polymerization: After heat preservation for 40 minutes, uniformly add shell monomer mixture B over 50 minutes.

[0071] Step 4, Post-treatment: Heat to 87℃ and hold for 1.2 hours (ensuring monomer conversion rate is greater than 99.5%). After cooling, use oxidation-reduction to eliminate the impurities. Adjust the pH to 8.5 with 2-amino-2-methyl-1-propanol (AMP-95) and filter to obtain emulsion E3.

[0072] Comparative Example 1 (CE1)

[0073] Referring to Example 1, no core-shell structure was constructed, and diacetone acrylamide (DAAM) and vinyltrimethoxysilane (VTMS) were contained. The mixed monomers were: 65 parts VAc, 28 parts VeoVa 10, 5 parts MMA, and 1.2 parts acrylic acid. All pre-emulsions were added dropwise simultaneously over 3.5 hours at a temperature of 80±2°C, then heated to 85°C and held for 1.5 hours. The mixture was then cooled, the residue was eliminated, the pH was adjusted, and the mixture was filtered to obtain emulsion CE1.

[0074] Comparative Example 2 (CE2)

[0075] Except for the absence of diacetone acrylamide (DAAM) in the preparation of preemulsion A, the monomer composition, emulsifier, and polymerization process steps were exactly the same as in Example 1, yielding emulsion CE2. Adipate dihydrazide (ADH) was not added when formulating the coating.

[0076] Comparative Example 3 (CE3)

[0077] Except for the absence of vinyltrimethoxysilane (VTMS) in the preparation of preemulsion A, the composition and process were exactly the same as in Example 1, resulting in emulsion CE3.

[0078] Comparative Example 4 (CE4)

[0079] The composite emulsifier (COPS-1 + isotridecyl alcohol polyoxyethylene ether) in Example 1 was completely replaced with an equal mass of isotridecyl alcohol polyoxyethylene ether (single nonionic emulsifier), with the total amount ratio remaining unchanged. The polymerization process was the same as in Example 1, and emulsion CE4 was obtained.

[0080] Effect Example

[0081] In the post-processing stage, the pH value of the emulsions in each embodiment was adjusted to the target range: E1 was adjusted to 8.0, E2 to 8.2, and E3 to 8.5.

[0082] The bulk properties of the emulsions prepared in the above embodiments were measured, and the results are shown in Table 7.

[0083] Table 7 Comparison of emulsion performance between each example and the comparative example

[0084] Testing items E1 E2 E3 CE1 CE2 CE3 CE4 Test standards / methods Solid content (%) 50.3 49.8 50.6 50.1 50.2 50.0 50.4 GB / T20623-2025 Particle size 145 152 138 168 150 146 235 Dynamic light scattering method PDI 0.056 0.062 0.048 0.085 0.065 0.06 0.142 Dynamic light scattering method Viscosity 385 312 428 295 345 378 685 Rotational viscometer, 3# 30r Core layer Tg (°C) 28.6 24.1 33.2 - 28.2 28.4 27.9 Shell Tg (°C) 5.2 3.8 8.5 - 5 5.1 4.9 Overall Tg (°C) 22.1 18.5 26.3 21.5 21 21.8 20.5 Calcium ion stability pass pass pass pass pass pass De-milk formation, flocculation GB / T20623-2025 Mechanical stability pass pass pass pass pass pass There is a lot of gel GB / T20623-2025 freeze-thaw stability pass pass pass pass pass pass Slight stratification GB / T9268-2008

[0085] The emulsion solids content of each embodiment was approximately 50±1%, which meets the requirements for industrial applications, and the batch-to-batch consistency was good.

[0086] In the embodiments of this invention (E1-E3), the emulsion particle size was all within the range of 135-155 nm, and the PDI < 0.07, indicating that the latex particles were narrowly distributed and uniform in size. Comparative Example 4 (CE4), due to the use of a single nonionic emulsifier, showed a significantly increased particle size (235 nm) and a significantly higher PDI (0.142), confirming the crucial role of the composite emulsification system in controlling particle size distribution.

[0087] The emulsion viscosity in the examples was controlled within the range of 300-450 mPa·s, exhibiting good workability and leveling properties. Comparative Example 4 (CE4) showed an abnormally high viscosity (685 mPa·s) and poor stability, further confirming the necessity of the composite emulsion system.

[0088] The core and shell Tg were determined by differential scanning calorimetry (DSC) using a two-stage heating scan (heating rate 10 °C / min). Two independent glass transition steps, corresponding to the core and shell respectively, were clearly distinguishable from the DSC curves. The overall Tg was obtained as the weighted average of the two Tg peaks in the DSC curve, or as a single Tg value directly measured from the DSC curve (for homogeneous structures).

[0089] Comparative Example 1 (CE1) uses homogeneous polymerization, and its DSC curve only shows a broadened Tg peak (about 21.5℃), making it impossible to distinguish the core-shell structure.

[0090] The DSC curves of all embodiments (E1-E3) clearly show two independent glass transition steps:

[0091] The core layer has a Tg of 24-33℃ (E1-E3), providing the rigid framework required for the coating film.

[0092] The shell Tg is 3-9℃, which ensures good low-temperature film formation and flexibility.

[0093] This data strongly supports the construction of the "hard core-soft shell" structure of this invention, proving that the gradient distribution of the internal composition and properties of latex particles was successfully achieved through a stepwise polymerization process.

[0094] The above examples (E1-E3) and comparative examples (CE1-CE4) were formulated into interior wall latex paints using the same basic formula (as shown in Table 8), and comprehensive performance tests were conducted according to the corresponding national standards. The results are shown in Table 9. No ADH was added to CE1, CE3, and CE4; no ADH was added to CE2 because it does not contain DAAM; for E1-E3 (containing DAAM), an ADH aqueous solution (prepared as a 10% aqueous solution) was added during the paint mixing stage. The specific amounts used in each example were: 1.6 parts for E1, 1.3 parts for E2, and 2.4 parts for E3.

[0095] Table 8 Latex Paint Formulas

[0096] Components Raw material name weight Grinding stage 1 Deionized water 250 2 Hydroxyethyl cellulose (HEC25000) 3.5 3 Ammonia (28%) 1.5 4 Dispersant (sodium polyacrylate) 6 5 Wetting agent (alkyl polyoxyethylene ether) 1.5 6 Defoamers (mineral oils) 1.5 7 Rutile titanium dioxide (R996) 180 8 Calcined kaolin (1250 mesh) 80 9 Heavy calcium carbonate (800 mesh) 150 Paint mixing stage 10 lotion 280 11 Alcohol ester dodecyl 12 12 Defoamers (mineral oils) 1.5 13 Bactericide (BIT) 1.5 14 Antifungal agents (OIT type) 1 15 Thickeners (polyurethane type) 2.5 16 Thickeners (alkali-swellable type) 2.0 17 Adipic acid dihydrazide (ADH, 10% aqueous solution) E1 - 1.6 parts, E2 - 1.3 parts, E3 - 2.4 parts, CE1~CE4 - 0 parts total 1000 (including appropriate amount of water to 1000 servings)

[0097] Scrub resistance: Tested according to GB / T 9266-2009 "Determination of scrub resistance of architectural coatings", the number of times the coating is scrubbed repeatedly with a brush until it is damaged is used to characterize the resistance.

[0098] Comparison ratio: Tested according to GB / T9265-2024 "Synthetic Resin Emulsion Interior Wall Coatings".

[0099] Pencil hardness: Tested according to GB / T6739-2006 "Determination of paint film hardness by pencil method for paints and varnishes".

[0100] Water resistance: Tested according to GB / T9265-2024 "Synthetic Resin Emulsion Interior Wall Coatings", characterized by whether the paint film has lost its gloss, changed color, blistered, wrinkled, peeled off, rusted, etc.

[0101] Alkali resistance: Tested according to GB / T9265-2009 "Determination of alkali resistance of architectural coatings", the coating film is immersed in saturated Ca(OH)2 solution and characterized by no abnormal phenomena such as blistering, softening, or peeling within a specified time.

[0102] Stain resistance: Apply the same thickness of soy sauce to the paint film test panel, leave it for 2 hours, and then wipe it off. Rate it according to four levels: very easy to clean / easy to clean / relatively difficult to clean / difficult to clean.

[0103] Storage stability: Tested in accordance with GB / T6753.3-1986 "Test Method for Storage Stability of Coatings".

[0104] Table 9 Comparison of coating film performance between each embodiment and the comparative example

[0105] Testing items E1 E2 E3 CE1 CE2 CE3 CE4 Test standards / methods Washing resistance 12450 8760 15820 4230 6480 10520 9020* GB / T9266-2009 Contrast ratio 0.96 0.95 0.96 0.93 0.94 0.96 0.95 GB / T9265-2024 (White) Pencil hardness HB B H 2B B HB HB GB / T6739-2006 Water resistance No abnormalities No abnormalities No abnormalities Noticeable bubbling Slight bubbling No abnormalities No abnormalities GB / T9265-2024 (96H) Alkali resistance No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities GB / T9265-2009 (24H) Stain resistance Very easy to clean Easy to clean Very easy to clean Difficult to clean Easy to clean Difficult to clean Easy to clean Apply soy sauce and wipe off after 2 hours. Storage stability good good good good Slightly thickened good Severe thickening GB / T6753.3-1986 (50℃, 30 days)

[0106] Note: Due to its poor stability, CE4 emulsion underwent flocculation during the paint-making process. Although it was strongly dispersed before application, the uniformity of the paint film was damaged. The measured scrub resistance data fluctuated greatly, and the appearance of the paint film was poor. This data is for reference only. As shown in Table 9, the interior wall latex paints prepared with the core-shell acetate emulsions for interior walls in Examples E1-E3 of this invention all achieved a scrub resistance of over 8000 cycles, with E1 reaching 12450 cycles and E3 reaching 15820 cycles. These results far exceed the requirements of the national standard GB / T 9756-2018 for superior grade products (greater than 6000 cycles) and the test results of comparative examples CE1-CE4. At the same time, they also showed excellent performance in terms of adhesion, storage stability, and other comprehensive properties, fully verifying the synergistic effect of the core-shell polymerization process and functional monomer system of this invention.

[0107] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A process for the preparation of a core-shell vinyl acetate tertiary emulsion for interior walls, characterized by, Includes the following steps: (1) Preparation of pre-emulsion A: Mix deionized water, composite emulsifier and pH buffer evenly, add core layer mixed monomer under stirring, emulsify evenly to obtain pre-emulsion A; The core layer mixed monomer is composed of the following monomers in parts by weight: 50-70 parts of vinyl acetate, 25-40 parts of vinyl tert-carbonate, 3-10 parts of (meth)acrylate C1-C4 alkyl ester, 1-3 parts of carboxylic acid functional monomer containing double bonds, 0.5-2 parts of diacetone acrylamide, and 0.5-2 parts of organosilicon modified monomer. (2) Preparation of seed emulsion: Add 25%-45% of deionized water, 0-40% of composite emulsifier and pH buffer to the reaction vessel, heat to 75-80℃, add 10-20% of initiator solution, keep warm for 10 minutes, then add 10-15% of pre-emulsion A and 20-30% of initiator solution to the reaction vessel simultaneously over 1-1.5 hours, keep warm for 30 minutes to obtain seed emulsion; (3) Core layer polymerization: The remaining pre-emulsion A and the initiator solution are simultaneously added dropwise to the seed emulsion at 78-82℃, and the addition is completed within 2.5-3.5 hours. The mixture is kept warm for 30 minutes. (4) Shell polymerization: The shell monomer mixture B is added dropwise to the core polymerization product over 0.5-1 hour. The shell monomer mixture B comprises, by weight, 2-5 parts of (meth)acrylate hydroxyalkyl ester, 0.5-1.5 parts of (meth)acrylate adhesion promoter monomer with phosphate ester groups directly bonded to the 2-3 carbon hydroxyl side chains, and 4-10 parts of vinyl acetate. (5) Post-treatment: Heat to 85-88℃ and keep warm for 1 hour, cool down to below 60℃ and add redox post-elimination agent, adjust pH to 7.5-8.5, filter and discharge to obtain the core shell acetic acid tert-emulsion for interior walls.

2. A process for the preparation of a core-shell vinyl acetate tertiary emulsion for interior wall use according to claim 1, characterized in that, In step (1), the composite emulsifier is a mixture of anionic emulsifier and nonionic emulsifier in a mass ratio of 1.5:1 to 2.5:1, and the total amount used accounts for 1.5%-3.0% of the total mass of the core-layer mixed monomers; the anionic emulsifier is selected from one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate or sodium allyloxyhydroxypropyl sulfonate; the nonionic emulsifier is selected from one or more of alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether or isomeric tridecyl alcohol polyoxyethylene ether.

3. A process for the preparation of a core-shell vinyl acetate tertiary emulsion for interior wall use according to claim 1, characterized in that, In step (1), the (meth)acrylic acid C1-C4 alkyl ester is methyl methacrylate; the organosilicon modified monomer in step (1) is one of vinyltrimethoxysilane or γ-(methacryloyloxy)propyltrimethoxysilane; the carboxylic acid functional monomer containing double bonds in step (1) is one or more of acrylic acid, methacrylic acid or itaconic acid.

4. A process for the preparation of a core-shell vinyl acetate tertiary emulsion for interior wall use according to claim 1, characterized in that, The (meth)acrylate adhesion promoter monomer with a molecular weight ≤400, in step (4) having the phosphate group directly bonded to the 2-3 carbon hydroxyl side chain, is one or more of hydroxyethyl methacrylate phosphate monoester, hydroxyethyl methacrylate phosphate dieester, or hydroxypropyl methacrylate phosphate.

5. A process for the preparation of a core-shell vinyl acetate tertiary emulsion for interior wall use as claimed in claim 1, wherein, The hydroxyalkyl methacrylate mentioned in step (4) is one or both of hydroxyethyl acrylate or hydroxypropyl methacrylate.

6. The method for preparing a core-shell acetate emulsion for interior walls according to claim 1, characterized in that, The initiator is an aqueous solution of ammonium persulfate or potassium persulfate, and its total amount accounts for 0.4%-1.0% of the total mass of the monomer.

7. A core-shell acetic acid emulsion for interior walls, characterized in that, The emulsion has a core-shell structure: The core layer is copolymerized from the following monomers in parts by weight: 50-70 parts vinyl acetate, 25-40 parts ethylene tert-carbonate, 3-10 parts C1-C4 alkyl methacrylate, 1-3 parts carboxylic acid functional monomers containing double bonds, 0.5-2 parts diacetone acrylamide, and 0.5-2 parts organosilicon modified monomers. The shell is copolymerized from the following monomers in parts by weight: 2-5 parts of hydroxyalkyl methacrylate, 0.5-1.5 parts of methacrylate adhesion promoter monomers with phosphate groups directly bonded to the 2-3 carbon hydroxyl side chains, and 4-10 parts of vinyl acetate. In the core layer, diacetone acrylamide is bonded to the polymer chain in the form of amide groups, which is used to undergo a ketone-hydrazide crosslinking reaction with adipic acid dihydrazide.

8. The core-shell acetate emulsion for interior walls according to claim 7, characterized in that, The emulsion has a solid content of 48%-52%, a pH of 7.5-8.5, and a latex particle size of 80-200 nm.

9. An interior wall latex paint, characterized in that, Included in parts by weight: 200-350 parts of the acetic acid emulsion as described in claim 7 or 8; 150-250 parts of rutile titanium dioxide; 150-300 parts of filler; 5-10 parts of dispersant; 8-15 parts of film-forming aid; Thickener 2-5 parts; 2-8 parts of adipic acid dihydrazide; Add an appropriate amount of deionized water to 1000 parts; The molar ratio of the adipic acid dihydrazide to the diacetone acrylamide in the acetic acid emulsion is 0.8:1 to 1.2:

1.

10. The interior wall latex paint according to claim 9, characterized in that, The filler is one or two of heavy calcium carbonate and calcined kaolin.