SVOC-free acrylate emulsion for building interior wall coating, preparation method therefor, and use thereof

Abstract

Disclosed in the present invention are an SVOC-free acrylate emulsion for a building interior wall coating, a preparation method therefor, and a use thereof. Raw materials for forming the acrylate emulsion comprise, in parts by weight, the following components: 20-40 parts of an acrylate monomer, 5-20 parts of an ethylene monomer, 0.2-2 parts of a carboxyl-containing monomer, 0.5-2.5 parts of a functional monomer, 50-65 parts of deionized water, and an auxiliary agent comprising 1-3 parts of an emulsifier, 0.1-3 parts of an initiator, 0.1-3 parts of an antifreeze agent, 0.1-2 parts of a pH stabilizer, and 0.05-1 parts of a post-treatment agent. By adding the acrylate emulsion in a small amount as one of raw materials of a building interior wall coating, a building interior wall coating having an excellent film-forming effect can be obtained without adding a film-forming additive, a coating layer film formed from the building interior wall coating is SVOC-free and exhibits the properties such as high scrub resistance at room temperature and low temperatures, high adhesion, and good resistance to thick-coating cracking.

Description

A zero-SVOC acrylic emulsion for interior wall coatings, its preparation method and application Technical Field

[0001] This invention relates to the field of architectural coatings. More specifically, it relates to a zero-SVOC acrylic emulsion for interior wall coatings, its preparation method, and its application. Background Technology

[0002] With social development and increased environmental awareness, there is growing concern about volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) in coatings. VOCs and SVOCs pose potential hazards to the environment and human health; therefore, reducing the emission of these harmful substances has become a crucial task for the coatings industry. While traditional acrylic emulsion coatings offer good film performance, they often contain a certain amount of VOCs and SVOCs, such as solvents, plasticizers, and other additives. These components are gradually released into the air during the drying and curing process. To reduce these emissions, various low-VOC and zero-VOC coating products have been developed. Among them, water-based acrylic emulsions are widely used in interior wall coatings due to their low VOC content. However, some low-VOC coatings currently on the market still contain small amounts of SVOCs, limiting their application in demanding fields such as hospitals, schools, and residences where indoor air quality requirements are higher. Therefore, developing a completely SVOC-free acrylic emulsion for interior wall coatings has become a current research hotspot.

[0003] EU Decision (EU) 2015 / 886 defines SVOCs as volatile organic compounds with a boiling point between 250°C and 370°C at 101.3 kPa standard atmospheric pressure and a retention time on a nonpolar chromatographic column between n-tetradecane (252°C) and n-dodecane (369°C) (inclusive of n-tetradecane and n-dodecane). Semi-volatile organic compounds (SVOCs) mainly include dioxins, polycyclic aromatic hydrocarbons, pyridines, quinolines, nitrobenzenes, phthalates, anilines, and phenols. These organic compounds exist primarily in the ambient air in either gaseous or aerosol form.

[0004] Currently, the film-forming aids used in interior wall coatings, such as alcohol ester twelve (C-12) and alcohol ester sixteen (C-16), fall within this range. From the composition of conventional interior wall coatings, VOCs and SVOCs in the coatings partly originate from residual monomers in the acrylic emulsion, neutralizing agents used in the emulsion and coating, antifreeze agents (such as ethylene glycol and propylene glycol), solvents in additives, and film-forming aids. Among these, film-forming aids are key agents that prevent cracking and ensure effective film formation during the film-forming process of interior wall coatings. To develop SVOC-free interior wall coatings, the amount of film-forming aids used must be almost zero or completely eliminated. However, using small amounts or no film-forming aids in traditional interior wall coatings results in poor film formation, consequently reducing scrub resistance and adhesion. This is a major challenge in developing zero-SVOC interior wall coatings. Based on the above description, achieving zero SVOC in interior wall coatings requires that the acrylic emulsion itself possess a certain film-forming aid function. Currently, there are no relevant patent documents describing the synthesis scheme of water-based acrylic emulsions for zero SVOC interior wall coatings, and there are no related acrylic emulsion products on the market that meet such requirements.

[0005] Some existing reports disclose pure acrylic emulsions for children's paints. These emulsions are zero VOC, require no antifreeze or film-forming aids, and exhibit good scrub resistance and freeze-thaw stability. This existing technology specifically emphasizes the use of zero-VOC emulsions in relatively environmentally friendly children's paints, but it cannot guarantee that the paint will be zero-VOC (additives with higher boiling points that aid film formation cannot be added), and the emulsion does not address scrub resistance at room temperature and low temperatures, or resistance to thick-coat cracking. Summary of the Invention

[0006] At least based on the above problems, the purpose of this invention is to provide a zero-SVOC acrylic emulsion for interior wall coatings, its preparation method, and its application. This acrylic emulsion is a zero-SVOC emulsion. By adding a small amount of this acrylic emulsion as one of the raw materials to an interior wall coating, an interior wall coating with excellent film-forming effect can be obtained without adding film-forming aids. Furthermore, the coating formed by this interior wall coating satisfies zero SVOC, as well as high scrub resistance at room temperature and low temperature, high adhesion, and good resistance to thick-film cracking.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] On one hand, the present invention provides a zero-SVOC acrylic emulsion for interior wall coatings, wherein the raw materials forming the acrylic emulsion, by weight, contain the following components:

[0009] 20-40 parts acrylate monomers, 5-20 parts ethylene monomers, 0.2-2 parts carboxyl-containing monomers, 0.5-2.5 parts functional monomers, 50-65 parts deionized water, and

[0010] The additives include 1-3 parts emulsifier, 0.1-3 parts initiator, 0.1-3 parts antifreeze, 0.1-2 parts pH stabilizer and 0.05-1 part post-treatment agent.

[0011] Further, the acrylate monomer is composed of acrylate monomer A and acrylate monomer B in a mass ratio of 1:(4-8); wherein,

[0012] Acrylate monomer A is selected from one or more of methyl methacrylate, tert-butyl methacrylate, hexadecyl methacrylate, octadecyl methacrylate, isobutyl methacrylate and isobornyl methacrylate;

[0013] Acrylate monomer B is selected from one or more of (meth)acrylate n-butyl acrylate, (meth)acrylate sec-butyl acrylate, (meth)acrylate isooctyl acrylate, (meth)acrylate diethylaminoethyl acrylate, isobutyl acrylate and methyl acrylate.

[0014] Furthermore, the acrylate monomer is composed of acrylate monomer A, n-butyl acrylate and isooctyl acrylate in a mass ratio of 1:(2-4):(1-4).

[0015] Furthermore, the ethylene monomer is selected from at least one of styrene, vinyl acetate, dichloroethylene, acrylonitrile, (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and divinylbenzene.

[0016] Furthermore, the ethylene monomer is composed of the following components 1) and 2):

[0017] 1) Styrene and / or vinyl acetate; and

[0018] 2) One or more of acrylamide, N,N-dimethyl (meth)acrylamide and N-hydroxymethyl (meth)acrylamide.

[0019] Furthermore, the ethylene monomer is obtained by compounding component 1) and component 2) in a mass ratio of (10-25):1.

[0020] Furthermore, the functional monomer is selected from one or more of 3-(methacryloyloxy)propyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxysilane), ethylidene methacrylate, glycidyl methacrylate, ethylene glycol acetoacetate methacrylate, m-phenylenediamine, butanediol diacrylate, allyl methacrylate, and olefinic phosphate functional monomers.

[0021] Furthermore, the functional monomer is obtained by compounding an olefinic phosphate functional monomer, ethylidene methacrylate, and ethylene glycol acetoacetate in a mass ratio of 1:(1-2):(5-10).

[0022] Furthermore, the emulsifier is composed of anionic emulsifier and nonionic emulsifier in a mass ratio of (1-5):1.

[0023] Furthermore, the anionic emulsifier is selected from one or more of allyloxyisomeric alcohol ether sulfate ammonium salt, fatty alcohol ether sulfate sodium salt, sodium dodecyl sulfate, and sodium dodecyl diphenyl ether disulfonate.

[0024] Furthermore, the nonionic emulsifier is selected from one or more of alkyl polyoxyethylene ether emulsifiers, tallow fatty alcohol polyoxyethylene ethers, and fatty alcohol polyoxyethylene ethers.

[0025] Furthermore, the carboxyl-containing monomer is selected from at least one of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid.

[0026] Furthermore, the pH stabilizer is selected from one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, and potassium carbonate.

[0027] Furthermore, the post-treatment agent is composed of an oxidant and a reducing agent in a mass ratio of 1:(1-2).

[0028] Furthermore, the oxidant is selected from tert-butyl hydrogen peroxide and / or hydrogen peroxide.

[0029] Furthermore, the reducing agent is selected from one or more of sodium isoascorbate, sodium bisulfite, sodium metabisulfite, Bruggolite FF6M, and Bruggolite TP1646.

[0030] In a second aspect, the present invention provides a method for preparing the acrylate emulsion as described in the first aspect above, the method comprising the following steps:

[0031] Mix 5-8 wt% of emulsifier with a portion of deionized water in a reaction vessel, and heat to 80-90°C under a nitrogen atmosphere to obtain the first solution;

[0032] The remaining emulsifier, acrylate monomers, ethylene monomers, carboxyl-containing monomers, functional monomers, and a portion of deionized water are mixed evenly to obtain a pre-emulsion.

[0033] The initiator was mixed with the remaining deionized water to obtain an initiator solution;

[0034] At a temperature of 80-95℃, 1-10 wt% of pre-emulsion and 10-60 wt% of initiator solution are added to the reactor containing the first solution. After mixing and reacting for 10-20 minutes, the remaining pre-emulsion and initiator solution are added dropwise. The total time for adding the remaining pre-emulsion is controlled within 120-180 minutes, and the addition of the remaining initiator solution is ensured to be completed 10-20 minutes later than the addition of the remaining pre-emulsion.

[0035] At a temperature of 50-70℃, a post-treatment agent is added to the system obtained after the above reaction. After keeping it at this temperature, the temperature is lowered to 15-45℃, an antifreeze agent is added, and then a pH stabilizer is added to adjust the pH to 7-9. The mixture is then filtered to obtain the acrylate emulsion.

[0036] Thirdly, the present invention provides a zero SVOC interior wall coating for building, characterized in that the raw materials forming the coating include the acrylic emulsion as described in the first aspect above.

[0037] Furthermore, the raw materials used to form the coating do not contain film-forming aids; and / or

[0038] The raw materials forming the coating, based on 100 parts by weight, contain 15-40 parts or 15-20 parts of the acrylic emulsion.

[0039] Fourthly, the present invention provides the application of the acrylic emulsion as described in the first aspect above in interior wall coatings for buildings.

[0040] The beneficial effects of this invention are as follows:

[0041] The acrylic emulsion provided by this invention, through the design of the raw material formulation and the selection of the preferred preparation process, enables the resulting interior wall coating to achieve zero SVOC without any film-forming aids, while also exhibiting excellent film-forming properties at both room temperature and low temperature. The addition amount of this acrylic emulsion in interior wall coatings can be high or low (e.g., only 15-20 wt%), effectively solving the current problem that interior wall coatings require the addition of more than 30 wt% acrylic emulsion to meet performance requirements such as high scrub resistance and resistance to thick-coat cracking.

[0042] In the preparation process of the acrylic emulsion provided in this invention, a single-phase structure is used instead of a complex core-shell structure. Furthermore, the seed nucleation process, monomer ratio, and emulsifier are optimized to ensure good polymerization stability of the emulsion. The latex paint (i.e., the interior wall coating for building) formulated with a smaller amount of this acrylic emulsion can withstand 6 cycles of low-temperature stability, exhibiting excellent freeze-thaw stability, as well as room temperature, low temperature scrub resistance, and film-forming properties. Detailed Implementation

[0043] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0044] Interior wall coatings are generally used in various interior wall applications, including those using loose putty and standard putty. Typically, for corners or areas obscured by equipment (such as appliances) where even spraying is difficult, multiple coats are applied manually. However, after multiple coats (i.e., thick coats), the resulting coating is prone to cracking due to increased thickness. Furthermore, it is difficult for typical interior wall coatings to prevent cracking even with thick coats at both low temperatures (5℃) and room temperatures (25℃).

[0045] Furthermore, in order to provide environmentally friendly interior wall coatings that meet the requirements of zero SVOC and still possess excellent freeze-thaw resistance, excellent scrub resistance at room temperature and low temperature, freeze-thaw stability, high adhesion, and resistance to cracking of thick coatings (e.g., 280-400 μm) without the presence of film-forming aids, one specific embodiment of the present invention provides a zero SVOC acrylic emulsion for interior wall coatings, wherein the raw materials forming the acrylic emulsion, by weight, contain the following components:

[0046] 20-40 parts acrylate monomers, 5-20 parts ethylene monomers, 0.2-2 parts carboxyl-containing monomers, 0.5-2.5 parts functional monomers, 50-65 parts deionized water, and

[0047] The additives include 1-3 parts emulsifier, 0.1-3 parts initiator, 0.1-3 parts antifreeze, 0.1-2 parts pH stabilizer and 0.05-1 part post-treatment agent.

[0048] In some preferred embodiments, the acrylate monomer is composed of acrylate monomer A and acrylate monomer B in a mass ratio of 1:(4-8); wherein,

[0049] Acrylate monomer A is selected from one or more of methyl methacrylate, tert-butyl methacrylate, hexadecyl methacrylate, octadecyl methacrylate, isobutyl methacrylate and isobornyl methacrylate;

[0050] Acrylate monomer B is selected from one or more of (meth)acrylate n-butyl acrylate, (meth)acrylate sec-butyl acrylate, (meth)acrylate isooctyl acrylate, (meth)acrylate diethylaminoethyl acrylate, isobutyl acrylate and methyl acrylate.

[0051] In the raw materials, acrylate monomer A provides the emulsion with good scrub resistance, and acrylate monomer B provides the emulsion with good resistance to thick-coat cracking. When the two are blended in a certain mass ratio, the resulting coating, when applied to interior wall coatings, exhibits suitable hardness and brittleness, and improved resistance to thick-coat cracking, while achieving zero SVOC.

[0052] In some preferred examples, the acrylate monomer A and acrylate monomer B are in a mass ratio of 1:(5-8). In this case, the coating obtained after application of an interior wall coating containing only a small amount (15-20 wt%) of the acrylate emulsion exhibits superior freeze-thaw stability, scrub resistance at room temperature (e.g., 25°C) and low temperature (5°C and below), adhesion, and resistance to thick-coat cracking. In some specific examples, the mass ratio of acrylate monomer A to acrylate monomer B includes, but is not limited to, 1:(5-7), 1:(5-6), 1:(5.2-6), 1:(5.4-6), etc. Under these conditions, the aforementioned effects are even better.

[0053] In some preferred examples, the acrylate monomer is composed of acrylate monomer A, n-butyl acrylate, and isooctyl acrylate in a mass ratio of 1:(2-4):(1-4). The resulting emulsion, when added in a small amount to interior wall coatings, produces a thick-coated layer with excellent freeze-thaw stability, scrub resistance at room temperature and low temperatures, adhesion, and resistance to thick-coating cracking.

[0054] In some more specific examples, the acrylate monomers are a mixture of methacrylate, n-butyl acrylate, and isooctyl acrylate in a mass ratio of 1:(2.5-4):(1.5-3.5). In this case, the aforementioned effects are even better.

[0055] In some examples, the content of acrylate monomers in the raw material, by weight, includes, but is not limited to, 25-40 parts, 28-40 parts, 30-40 parts, etc.

[0056] In some examples, the ethylene monomer is selected from at least one of styrene, vinyl acetate, dichloroethylene, acrylonitrile, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and divinylbenzene.

[0057] In some preferred embodiments, the ethylene monomer comprises the following components 1) and 2):

[0058] 1) Styrene and / or vinyl acetate; and

[0059] 2) One or more of acrylamide, N,N-dimethyl (meth)acrylamide and N-hydroxymethyl (meth)acrylamide.

[0060] In the ethylene monomer, components 1) and 2) are used together, wherein component 1) can provide better scrub resistance and component 2) can increase the stability during emulsion polymerization.

[0061] In some examples, the ethylene monomer is obtained by compounding component 1) and component 2) in a mass ratio of (10-25):1. More preferably, the mass ratio is (10-20):1. Under these conditions, the coating film exhibits better crack resistance at both room temperature and low temperature.

[0062] In some more preferred examples, the ethylene monomer is a mixture of styrene and acrylamide in a mass ratio of (10-25):1, preferably (10-20):1.

[0063] In some examples, the content of ethylene monomers in the raw material, by weight, includes, but is not limited to, 5-15 parts, 5-12 parts, etc.

[0064] In some examples, the functional monomer is selected from one or more of 3-(methacryloyloxy)propyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxysilane), ethylidene methacrylate, glycidyl methacrylate, ethylene glycol acetoacetate methacrylate, m-phenylenediamine, butanediol diacrylate, allyl methacrylate, and olefinic phosphate functional monomers.

[0065] For example, the olefinic phosphate functional monomers include, but are not limited to, one or more selected from Solvay's SIPOMER PAM100, SIPOMER PAM200 and SIPOMER PAM 4000.

[0066] In some examples, the functional monomer is obtained by compounding an olefinic phosphate functional monomer, ethylidene methacrylate, and ethylene glycol acetoacetate in a mass ratio of 1:(1-2):(5-10). The use of functional monomers compounded under these conditions imparts superior scrub resistance to the coating film at both room temperature and low temperature.

[0067] In some preferred examples, the functional monomer is obtained by compounding an olefinic phosphate functional monomer, ethylidene methacrylate, and ethylene glycol acetoacetate in a mass ratio of 1:2:9.

[0068] In some specific examples, the amount of functional monomers added to the raw materials, by weight, includes but is not limited to 1-2.5 parts, 1.5-2.5 parts, 2-2.5 parts, etc.

[0069] In some examples, the carboxyl-containing monomer is selected from at least one of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid. The carboxyl-containing monomer is a hydrophilic monomer, which can improve the stability of the emulsion during polymerization.

[0070] In some preferred embodiments, the carboxyl-containing monomer is itaconic acid. Under these conditions, the scrub resistance of the coating at room temperature and low temperature can be further improved.

[0071] In some specific examples, the amount of the carboxyl-containing monomer added to the raw material, by weight, includes but is not limited to 0.5-2 parts, 0.5-1 parts, etc.

[0072] In some examples, the emulsifier consists of anionic and nonionic emulsifiers in a mass ratio of (1-5):1. Preferably, the emulsifier consists of anionic and nonionic emulsifiers in a mass ratio of (3-5):1, more preferably (3.5-5):1. Anionic emulsifiers provide better emulsification, while nonionic emulsifiers can provide a hydration layer, increasing the stability of metal ions.

[0073] In some examples, the anionic emulsifier is selected from one or more of allyloxyisomeric alcohol ether sulfates (e.g., Adico's Reasoap SR-1025), sodium fatty alcohol ether sulfates (e.g., BASF's Disponil FES27, Disponil FES 32, Disponil FES 993IS), sodium dodecyl sulfate (e.g., BASF's Disponil SLS103), and sodium dodecyl diphenyl ether disulfonate (e.g., Dow's DOW FAX2A1).

[0074] In some preferred examples, the anionic emulsifier is selected from one or more of allyloxyisomeric alcohol ether sulfates (e.g., Idicco's Reasoap SR-1025), fatty alcohol ether sulfates (e.g., BASF's Disponil FES 32, Disponil FES 993IS), and sodium dodecyl diphenyl ether disulfonate (e.g., Dow's DOW FAX2A1). By preferably combining specific anionic emulsifiers with nonionic emulsifiers, the coating film is endowed with superior room temperature and low temperature scrub resistance and resistance to thick coating cracking.

[0075] In some examples, the nonionic emulsifier is selected from one or more of alkyl polyoxyethylene ether emulsifiers (e.g., Clariant's Emulsogen LCN 118), tallow fatty alcohol polyoxyethylene ethers (e.g., BASF's Lutensol AT80), and fatty alcohol polyoxyethylene ethers (e.g., BASF's Lutensol TO 89).

[0076] In some examples, the pH stabilizer is selected from one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, and potassium carbonate.

[0077] In some examples, the post-treatment agent consists of an oxidant and a reducing agent in a mass ratio of 1:(1-2). The combination of oxidant and reducing agent generates free radicals during the preparation of the acrylate emulsion. These free radicals can react with residual monomers in the system, thereby improving the conversion rate.

[0078] In some examples, the oxidant is selected from tert-butyl hydrogen peroxide and / or hydrogen peroxide.

[0079] In some examples, the reducing agent is selected from one or more of sodium isoascorbate, sodium bisulfite, sodium metabisulfite, Bruggolite FF6M, and Bruggolite TP1646.

[0080] In some examples, the initiator is selected from sodium persulfate.

[0081] In some examples, the antifreeze includes, but is not limited to, those selected from Solvay. Examples of antifreeze agents include FT-100, Ashland's Stodex FT-68, and Stodex FT-88. The presence of antifreeze agents can prevent the prepared acrylate emulsion from crystallizing at low temperatures, thus improving the freeze-thaw cycle stability of the emulsion.

[0082] In some examples, the total weight of the raw materials forming the acrylate emulsion is 100 parts.

[0083] According to another specific embodiment of the present invention, a method for preparing the acrylate emulsion as described above is provided, the method comprising the following steps:

[0084] Mix 5-8 wt% of emulsifier with a portion of deionized water in a reaction vessel, and heat to 80-90°C under a nitrogen atmosphere to obtain the first solution;

[0085] The remaining emulsifier, acrylate monomers, ethylene monomers, carboxyl-containing monomers, functional monomers, and a portion of deionized water are mixed evenly to obtain a pre-emulsion.

[0086] The initiator was mixed with the remaining deionized water to obtain an initiator solution;

[0087] At a temperature of 80-95℃, 1-10 wt% of pre-emulsion and 10-60 wt% of initiator solution are added to the reactor containing the first solution. After mixing and reacting for 10-20 minutes, the remaining pre-emulsion and initiator solution are added dropwise. The total time for adding the remaining pre-emulsion is controlled within 120-180 minutes, and the addition of the remaining initiator solution is ensured to be completed 10-20 minutes later than the addition of the remaining pre-emulsion.

[0088] At a temperature of 50-70℃, a post-treatment agent is added to the system obtained after the above reaction. After keeping it at this temperature, the temperature is lowered to 15-45℃, an antifreeze agent is added, and then a pH stabilizer is added to adjust the pH to 7-9. The mixture is then filtered to obtain the acrylate emulsion.

[0089] In the above preparation method, the method of first adding a specific amount of pre-emulsion and initiator solution to a reaction vessel containing the first solution, mixing and reacting for 10-20 minutes, and then adding the subsequent solution dropwise can effectively control the particle size of the obtained acrylic emulsion, ensure the stability of the product, and thus give the thick coating of the building interior wall paint excellent anti-cracking effect at room temperature and low temperature.

[0090] In some examples, the heat preservation time is 0.5-1 hour.

[0091] According to another specific embodiment of the present invention, a zero SVOC interior wall coating for building is provided, wherein the raw materials for forming the coating include an acrylic emulsion as described above.

[0092] In some examples, the raw materials used to form the coating do not contain film-forming aids.

[0093] In some examples, the raw materials forming the coating contain 15-40 parts or 15-20 parts of the acrylate emulsion, per 100 parts by weight.

[0094] In other words, this acrylic emulsion can be added at both low concentrations (15-20 wt%) and high concentrations (25-40 wt%) in interior wall coatings for building applications. When added at low concentrations, the resulting coating, without the presence of film-forming aids, not only achieves zero SVOC, but also exhibits excellent room temperature and low temperature crack resistance, scrub resistance, and freeze-thaw stability in thick-coated layers.

[0095] According to another specific embodiment of the present invention, the application of the acrylic emulsion as described above in interior wall coatings for buildings is provided.

[0096] The technical solution of the present invention will be described below with reference to some specific embodiments:

[0097] Example 1

[0098] An acrylic emulsion for interior wall coatings is prepared from raw materials in the parts by weight shown in Table 1 below.

[0099] Table 1

[0100] The specific steps for preparing the acrylate emulsion according to the above formula include:

[0101] Add deionized water (25 parts), anionic emulsifier (0.1 parts), and nonionic emulsifier (0.05 parts) together to the reactor, purge with nitrogen, and heat to 85°C;

[0102] The pre-emulsion was prepared by stirring 17 parts of deionized water, the remaining anionic emulsifier, the remaining nonionic emulsifier, acrylate monomers, ethylene monomers, carboxyl-containing monomers, and functional monomers until they were evenly dispersed.

[0103] Mix the initiator with the remaining deionized water to obtain an initiator solution;

[0104] At 85°C, 10 wt% of pre-emulsion and 20 wt% of initiator solution were added to the aforementioned reactor and mixed for 15 minutes. Then, the remaining pre-emulsion and initiator solution were added dropwise. The total time for adding the pre-emulsion was controlled within 160 minutes, and the initiator solution was added 15 minutes later than the pre-emulsion. After the reaction was completed, the mixture was kept at the temperature for 30 minutes.

[0105] At 70°C, an oxidant and a reducing agent are added dropwise to the system, kept at this temperature for half an hour, then cooled to 30°C. The tailings antifreeze agent is added, and the pH is adjusted to 7.0-9.0 by neutralization with sodium hydroxide solution. The acrylate emulsion is then obtained by filtration.

[0106] Example 2

[0107] An acrylic emulsion for interior wall coatings is prepared from raw materials comprising the parts by weight shown in Table 2 below.

[0108] Table 2

[0109] The preparation method of the acrylic emulsion for interior wall coatings described above is the same as in Example 1.

[0110] Example 3

[0111] An acrylic emulsion for interior wall coatings is prepared from raw materials in the parts by weight shown in Table 3 below.

[0112] Table 3

[0113] The preparation method of the acrylic emulsion for interior wall coatings described above is the same as in Example 1.

[0114] Example 4

[0115] An acrylic emulsion for interior wall coatings is prepared from raw materials in the parts by weight shown in Table 4 below.

[0116] Table 4

[0117] The preparation method of the acrylic emulsion for interior wall coatings described above is the same as in Example 1.

[0118] Example 5

[0119] An acrylic emulsion for interior wall coatings is prepared from raw materials in the parts by weight shown in Table 5 below.

[0120] Table 5

[0121] The preparation method of the acrylic emulsion for interior wall coatings described above is the same as in Example 1.

[0122] Comparative Example 1

[0123] An acrylic emulsion for interior wall coatings is prepared from raw materials in the parts by weight shown in Table 6 below.

[0124] Table 6

[0125] The preparation method of the acrylic emulsion for interior wall coatings described above is the same as in Example 1.

[0126] Comparative Example 2

[0127] An acrylic emulsion for interior wall coatings is prepared from raw materials in the parts by weight shown in Table 7 below.

[0128] Table 7

[0129] The preparation method of the acrylic emulsion for interior wall coatings described above is the same as in Example 1.

[0130] Comparative Example 3

[0131] An acrylic emulsion for interior wall coatings is prepared from raw materials in the parts by weight shown in Table 8 below.

[0132] Table 8

[0133] The preparation method of the acrylic emulsion for interior wall coatings described above is the same as in Example 1.

[0134] Comparative Example 4

[0135] An acrylic emulsion for interior wall coatings is prepared from raw materials in the parts by weight shown in Table 9 below.

[0136] Table 9

[0137] Comparative Example 5

[0138] An acrylic emulsion for interior wall coatings is prepared from raw materials in the parts by weight shown in Table 10 below.

[0139] Table 10

[0140] Comparative Example 6

[0141] An acrylic emulsion for interior wall coatings uses the same raw material formulation as in Example 1; the difference between the emulsion preparation method and Example 1 lies in the method of adding the pre-emulsion and initiator solution to the reaction vessel. Specifically, the difference is as follows:

[0142] At 85°C, 15 wt% of pre-emulsion and 5 wt% of initiator solution were added to the aforementioned reactor and mixed for 15 minutes. Then, the remaining pre-emulsion and initiator solution were added dropwise. The total time for adding the pre-emulsion was controlled within 140 minutes, and the initiator solution was added 15 minutes later than the pre-emulsion. After the reaction was completed, the mixture was kept at the temperature for 30 minutes.

[0143] With all other conditions remaining unchanged, an acrylic emulsion for interior wall coatings was obtained.

[0144] Comparative Example 7

[0145] An acrylic emulsion for interior wall coatings is prepared from raw materials in the parts by weight shown in Table 11 below.

[0146] Table 11

[0147] The preparation method of the acrylic emulsion for interior wall coatings described above is the same as in Example 1.

[0148] Comparative Example 8

[0149] An acrylic emulsion for interior wall coatings is prepared from raw materials in the parts by weight shown in Table 12 below.

[0150] Table 12

[0151] The preparation method of the acrylic emulsion for interior wall coatings described above is the same as in Example 1.

[0152] The above embodiments were formulated into coatings according to the following processes and formulations for performance evaluation.

[0153] Application of acrylic emulsions in interior wall coatings:

[0154] Application methods include:

[0155] The acrylic emulsions prepared in the various embodiments and comparative examples were used in interior wall coatings. Except for the aforementioned emulsion, all raw material components forming the coating were selected from conventional interior wall coating preparation components, which will not be elaborated here. Specifically, the raw materials forming the coating consisted of 18 parts of the aforementioned acrylic emulsion, 80 parts of the slurry, and 2 parts of deionized water. Generally, an acrylic emulsion content of 30 parts or more in interior wall coatings is required to achieve good scrub resistance and low-temperature thick-coating crack resistance. In this invention, a unique acrylic emulsion raw material formulation is creatively employed, giving the interior wall coating a zero SVOC effect, excellent scrub resistance, and good film-forming properties at both room temperature and low temperature. Preferably, the emulsion polymerization method further improves the low-temperature film-forming performance of the resin in the emulsion, allowing the performance of a conventional interior wall coating with approximately 30 parts acrylic emulsion content to be achieved even when the acrylic emulsion content in the coating is reduced to 15-20 parts.

[0156] The testing methods shall be carried out in accordance with the following standards:

[0157] Scrub resistance: As per GB / T 9756-2020, 5.5.11;

[0158] Freeze-thaw stability: Comply with 5.5.6 of GB / T 9756-2020;

[0159] Cracking of thick coatings at room temperature and low temperature: Follow the Nippon Paint product thick coating cracking simulation test method, and the main operations are as follows:

[0160] 1) Prepare two A4 general-purpose putty boards and two A4 loose putty boards;

[0161] 2) After performing simple dust removal treatment on each putty board, place it on an analytical balance;

[0162] 3) Use a damp wool brush to apply 40g of the interior wall paint evenly to each putty board (for superior grade products, use ≥40g of paint; for first grade and below, use ≥30g of paint. This test adopts the test method for superior grade products).

[0163] 4) Place one A4 general-purpose putty board and one A4 loose putty board coated with interior wall paint from step 3) into an environment of 25°C to form a film. Place another A4 general-purpose putty board and another A4 loose putty board coated with interior wall paint from step 3) into an environment of 5°C to form a film. Observe the cracking of the paint film after 24 hours. The dry film thickness is about 380μm.

[0164] 5) Evaluation method: All putty boards placed at 25℃ and 5℃ are considered to have passed if there are no obvious cracks on the paint film surface.

[0165] The performance test results of the interior wall coatings obtained using the acrylic emulsions of each embodiment and comparative example are shown in Table 13 below:

[0166] Table 13

[0167] This technical solution also focuses on the effect of the amount of acrylic emulsion added on the final coating performance. The results are shown in Table 14 below:

[0168] Table 14

[0169] As shown in Table 14, coatings with low resin content still meet the requirements of excellent scrub resistance, excellent freeze-thaw stability, and excellent resistance to thick coating cracking.

[0170] The semi-volatile organic compound (SVOC, g / L) content of the acrylic emulsions and the prepared interior wall coatings in each embodiment was tested. The test method was performed according to Appendix 11.4 of GB / T 23896.2-2023. The test results are shown in Table 15 below.

[0171] Table 15

[0172] Note: The acrylic emulsion used in the interior wall coating of this invention does not contain any low-boiling-point substances (such as film-forming aids, propylene glycol, etc.).

[0173] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A zero-SVOC acrylic emulsion for interior wall coatings, characterized in that, The raw materials forming the acrylate emulsion, by weight, contain the following components: 20-40 parts acrylate monomers, 5-20 parts ethylene monomers, 0.2-2 parts carboxyl-containing monomers, 0.5-2.5 parts functional monomers, 50-65 parts deionized water, and The additives include 1-3 parts emulsifier, 0.1-3 parts initiator, 0.1-3 parts antifreeze, 0.1-2 parts pH stabilizer and 0.05-1 part post-treatment agent.

2. The acrylate emulsion according to claim 1, characterized in that, The acrylate monomer is composed of acrylate monomer A and acrylate monomer B in a mass ratio of 1:(4-8); wherein, Acrylate monomer A is selected from one or more of methyl methacrylate, tert-butyl methacrylate, hexadecyl methacrylate, octadecyl methacrylate, isobutyl methacrylate and isobornyl methacrylate; Acrylate monomer B is selected from one or more of (meth)acrylate n-butyl acrylate, (meth)acrylate sec-butyl acrylate, (meth)acrylate isooctyl acrylate, (meth)acrylate diethylaminoethyl acrylate, isobutyl acrylate and methyl acrylate; Preferably, the acrylate monomer is composed of acrylate monomer A, n-butyl acrylate and isooctyl acrylate in a mass ratio of 1:(2-4):(1-4).

3. The acrylate emulsion according to claim 1, characterized in that, The ethylene monomers are selected from at least one of styrene, vinyl acetate, dichloroethylene, acrylonitrile, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide and divinylbenzene; Preferably, the ethylene monomer is composed of the following components 1) and 2): 1) Styrene and / or vinyl acetate; and 2) One or more of acrylamide, N,N-dimethyl (meth)acrylamide and N-hydroxymethyl (meth)acrylamide; More preferably, the ethylene monomer is obtained by compounding component 1) and component 2) in a mass ratio of (10-25):

1.

4. The acrylate emulsion according to claim 1, characterized in that, The functional monomers are selected from one or more of the following: 3-(methacryloyloxy)propyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxysilane), ethylidene methacrylate, glycidyl methacrylate, ethylene glycol acetoacetate methacrylate, m-phenylenediamine, butanediol diacrylate, allyl methacrylate, and olefinic phosphate functional monomers. Preferably, the functional monomer is obtained by compounding an olefinic phosphate functional monomer, ethylidene methacrylate, and ethylene glycol acetoacetate in a mass ratio of 1:(1-2):(5-10).

5. The acrylate emulsion according to claim 1, characterized in that, The emulsifier is composed of anionic emulsifier and nonionic emulsifier in a mass ratio of (1-5):1; Preferably, the anionic emulsifier is selected from one or more of allyloxyisomeric alcohol ether sulfate ammonium salt, fatty alcohol ether sulfate sodium salt, sodium dodecyl sulfate, and sodium dodecyl diphenyl ether disulfonate; Preferably, the nonionic emulsifier is selected from one or more of alkyl polyoxyethylene ether emulsifiers, tallow fatty alcohol polyoxyethylene ethers, and fatty alcohol polyoxyethylene ethers.

6. The acrylate emulsion according to claim 1, characterized in that, The carboxyl-containing monomer is selected from at least one of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid; and / or The pH stabilizer is selected from one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, and potassium carbonate.

7. The acrylate emulsion according to claim 1, characterized in that, The post-treatment agent is composed of an oxidant and a reducing agent in a mass ratio of 1:(1-2); Preferably, the oxidant is selected from tert-butyl hydrogen peroxide and / or hydrogen peroxide; Preferably, the reducing agent is selected from one or more of sodium isoascorbate, sodium bisulfite, sodium metabisulfite, Bruggolite FF6M, and Bruggolite TP1646.

8. The method for preparing the acrylate emulsion according to any one of claims 1-7, characterized in that, The steps include the following: Mix 5-8 wt% emulsifier with a portion of deionized water in a reaction vessel, and heat to 80-90℃ under a nitrogen atmosphere to obtain the first solution; The remaining emulsifier, acrylate monomers, ethylene monomers, carboxyl-containing monomers, functional monomers, and a portion of deionized water are mixed evenly to obtain a pre-emulsion. The initiator was mixed with the remaining deionized water to obtain an initiator solution; At a temperature of 80-95℃, 1-10 wt% of pre-emulsion and 10-60 wt% of initiator solution are added to the reactor containing the first solution. After mixing and reacting for 10-20 minutes, the remaining pre-emulsion and initiator solution are added dropwise. The total time for adding the remaining pre-emulsion is controlled within 120-180 minutes, and the addition of the remaining initiator solution is ensured to be completed 10-20 minutes later than the addition of the remaining pre-emulsion. At a temperature of 50-70℃, a post-treatment agent is added to the system obtained after the above reaction. After keeping it at this temperature, the temperature is lowered to 15-45℃, an antifreeze agent is added, and then a pH stabilizer is added to adjust the pH to 7-9. The mixture is then filtered to obtain the acrylate emulsion.

9. A zero-SVOC interior wall coating for building applications, characterized in that, The raw materials used to form the coating include the acrylic emulsion as described in any one of claims 1-7; Preferably, the raw materials used to form the coating do not contain film-forming aids; Preferably, the raw materials forming the coating contain 15-40 parts or 15-20 parts of the acrylic emulsion, based on 100 parts by weight.

10. The use of the acrylic emulsion as described in any one of claims 1-7 in interior wall coatings for building applications.

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