Water-based coating composition

Abstract

Embodiments of the present invention relate to aqueous coating compositions, such as paints or other architectural coatings. In one aspect, the aqueous coating composition comprises a binder and a film-forming aid according to Formula 1: X-O-(AO) m H (Formula 1) (wherein X is an alkyl group having 4 to 8 carbon atoms, AO is propylene oxide, or a mixture of ethylene oxide and propylene oxide in a block or random order, and m is from 1 to 10).

Description

Technical Field

[0001] The present invention relates to an aqueous coating composition.

Background Art

[0002] Introduction The continuous pursuit of high-performance coatings, such as paints and other architectural coatings, that are low in volatile organic compounds (VOCs) and have low odor has driven the development of new coating formulations. Among the various components in aqueous architectural coatings, coalescing agents, cosolvents, and freeze-thaw (F-T) agents are often considered to be the three main VOC contributors, based on the amounts used and their boiling points. Commonly used coalescing agents (e.g., ester alcohols), cosolvents (e.g., glycols and glycol ethers), and F-T agents (e.g., propylene glycol) are often considered to be VOC contributors in aqueous architectural coating formulations. Coalescing agents are important for providing good film formation in aqueous coating formulations.

[0003] However, it is a challenge to identify a coalescing agent that meets the low VOC target for aqueous coating formulations while providing properties that are the same as or comparable to those of coating formulations made with conventional high-VOC coalescing agents such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and glycol ethers. An important property of a coalescing agent is to form a homogeneous film and lower the temperature at which it is formed, but the coalescing agent should also not impair other coating properties such as hardness development, scrub resistance, and dirt removal. There is also a need to find new low-VOC coalescing agents that function well in a wider variety of resins such as acrylic, vinyl-acrylic, and styrene-acrylic emulsions.

[0004] It is desirable to have a novel aqueous coating composition having a low VOC content and / or improved coating performance characteristics. For example, it is also desirable to have a novel low VOC content film-forming aid that functions well in various resins such as acrylic, vinyl acrylic, and / or styrene acrylic emulsions.

Summary of the Invention

[0005] In some embodiments, the present invention provides an aqueous coating composition having a low VOC content and / or improved coating performance characteristics. Examples of such coating performance characteristics include, in some embodiments, a decrease in the minimum film formation temperature, scrub resistance, and coating stability.

[0006] In one aspect, the present invention provides an aqueous coating composition such as a paint, comprising a binder and a film-forming aid according to Formula 1: X-O-(AO) m H (Formula 1) (wherein X is an alkyl group having 4 to 8 carbon atoms, AO is propylene oxide, or a mixture of ethylene oxide and propylene oxide in a block or random order, and m is from 1 to 10).

[0007] These and other embodiments are described in more detail in the "Detailed Description of the Invention".

Detailed Description of the Invention

[0008] As used herein, "a", "an", "the", "at least one", and "one or more" are used interchangeably. "Comprise", "include", and their variants do not have a limiting meaning when these terms appear in the specification and claims. Thus, for example, an aqueous composition containing "a" hydrophobic polymer particle can be interpreted to mean that the composition contains "one or more" hydrophobic polymer particles.

[0009] Also, in this specification, the recitation of a numerical range by endpoints includes all numbers encompassed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). For the purposes of the present invention, it should be understood that, consistent with what those skilled in the art would understand, a numerical range is intended to include and support all sub-ranges that could possibly be included within that range. For example, a range of 1 to 100 is intended to convey 1.01 to 100, 1 to 99.99, 1.01 to 99.99, 40 to 60, 1 to 55, etc.

[0010] Some embodiments of the present invention relate to aqueous coating compositions, such as paints or other coatings. In some embodiments, the aqueous coating composition comprises a binder and a film-forming aid according to Formula 1: X-O-(AO) m H (Formula 1) (wherein X is an alkyl group having 4 to 8 carbon atoms, AO is propylene oxide, or a mixture of ethylene oxide and propylene oxide in a block or random order, and m is from 1 to 10). In some embodiments, X is n-butyl. In some embodiments, X is 2-ethylhexyl. In some embodiments, m is from 3 to 7. In some embodiments, m is 5. In some embodiments, the film-forming aid comprises 20 weight percent or less of ethylene oxide based on the weight of the film-forming aid.

[0011] In some embodiments, the molecular weight (M w ) of the film-forming aid is from 200 to 500.

[0012] In some embodiments, the binder is an aqueous polymer dispersion comprising an acrylic polymer, a styrene-acrylic copolymer, a vinyl acetate-acrylic copolymer, an ethylene-vinyl acetate copolymer, or a mixture thereof. In some embodiments where the binder is such an aqueous polymer dispersion, the aqueous coating composition comprises 5 to 70 weight percent of the polymer dispersion based on the total weight of the aqueous coating composition. In some embodiments, the aqueous coating composition comprises 10 to 70 weight percent of the polymer dispersion based on the total weight of the aqueous coating composition. In some embodiments, the aqueous coating composition comprises 15 to 60 weight percent of the polymer dispersion based on the total weight of the aqueous coating composition.

[0013] In some embodiments, the aqueous coating composition comprises 1 to 20 weight percent of a film-forming aid according to Formula 1 based on the weight of the binder on a total solids basis. In some embodiments, the aqueous coating composition of the present invention comprises 1 to 10 weight percent of a film-forming aid according to Formula 1 based on the weight of the binder on a total solids basis.

[0014] In some embodiments, the film-forming aid has a VOC content of less than 15% as measured according to EPA Method 24.

[0015] Film-forming aid The aqueous coating composition has the formula 1: X-O-(AO) m H (Formula 1) (wherein X is an alkyl group having 4 to 8 carbon atoms, AO is propylene oxide, or a mixture of ethylene oxide and propylene oxide in a block or random order, and m is from 1 to 10). In some embodiments, X is n-butyl. In some embodiments, X is 2-ethylhexyl. In some embodiments, m is from 3 to 7. In some embodiments, m is 5. In some embodiments, the film-forming aid comprises 20 weight percent or less of ethylene oxide based on the weight of the film-forming aid.

[0016] A "film-forming aid" means a component that promotes film formation of an aqueous coating composition containing a binder, particularly a binder that is a dispersion of a polymer in an aqueous medium (aqueous polymer dispersion), such as a polymer prepared by an emulsion polymerization technique. An indicator of the promotion of film formation is that the minimum film forming temperature ("MFFT") of the composition containing the binder (aqueous polymer dispersion) is reduced to a measurable extent by the addition of the film-forming aid. In other words, the MFFT value is an indicator of how efficient the film-forming aid is for a given aqueous polymer dispersion, and it is desirable to achieve the lowest possible MFFT with the minimum amount of film-forming aid. The MFFT of the aqueous coating composition herein is measured using ASTM D 2354 and the 5 mil MFFT bar described in the Examples section.

[0017] In some embodiments, the molecular weight (M w ) of the film-forming aid is from 200 to 500.

[0018] A non-limiting example of a compound according to Formula 1 that can be used as a film-forming aid in the aqueous coating composition according to some embodiments of the present invention is pentapropylene glycol 2-ethylhexyl ether. Another non-limiting example of a compound according to Formula 1 that can be used as a film-forming aid in the aqueous coating composition according to some embodiments of the present invention is polyalkylene glycol monobutyl ether, which is Film-Forming Aid 2 of the present invention described in the Examples section below.

[0019] In some embodiments, the aqueous coating composition of the present invention contains 1 to 20% by weight of the film-forming aid according to Formula 1 based on the weight of the binder on a total solids basis. In some embodiments, the aqueous coating composition of the present invention contains 1 to 10% by weight of the film-forming aid according to Formula 1 based on the weight of the binder on a total solids basis.

[0020] In some embodiments, the aqueous coating composition of the present invention can further include one or more other film-forming aids in addition to the film-forming aid according to Formula 1. In some embodiments, the additional film-forming aid may be a film-forming aid according to Formula 1 having a structure different from that of the first film-forming aid according to Formula 1. In some embodiments, the additional film-forming aid has a VOC content that is the same as or lower than that of the film-forming aid according to Formula 1.

[0021] The film-forming aid according to Formula 1 can be obtained by a conventional method by reacting an alkylene oxide such as propylene oxide or a combination of ethylene oxide and propylene oxide with an initiator in the presence of a catalyst for the ring-opening polymerization of alkylene oxides. The polymerization can be bulk polymerization or solution polymerization. Examples of suitable initiators include n-butanol, 2-ethylhexanol, isobutanol, tert-butanol, hexanol, 2-octanol, glycol, or mixtures thereof. The catalyst useful for the polymerization of alkylene oxides can be either anionic or cationic, and examples include potassium hydroxide, boron trifluoride, or a double cyanide complex (DMC) catalyst such as zinc hexacyanocobaltate. The alkylene oxide is typically supplied to a reactor containing the dry initiator and catalyst at a temperature varying from 50 °C to 140 °C. When the pressure in the reactor returns to approximately the same pressure as before the supply of the alkylene oxide, the polymerization is usually considered complete. The product is neutralized with an acid such as acetic acid or phosphoric acid, or a base such as sodium hydroxide (in the case of an acid catalyst such as boron trifluoride) to avoid catalytic oxidation.

[0022] Binder In addition to the film-forming aid of Formula 1, the aqueous coating composition of the present invention further comprises a binder. The binder may be part of an aqueous polymer dispersion containing a polymer, oligomer, prepolymer, or a combination thereof in an aqueous medium. In some embodiments, the aqueous polymer dispersion forms a film upon evaporation of water and can be reactive or non-reactive depending on the desired formulation. "Aqueous medium" as used herein means a medium containing at least 40% by weight of water based on the weight of the medium. The polymer, oligomer, prepolymer, or combination in the aqueous polymer dispersion is often referred to as the binder. The choice of binder is not particularly critical, and the binder can be selected from all types of binders known in the art, including, for example, acrylic polymers, styrene-acrylic copolymers, vinyl acetate-acrylic copolymers, ethylene-vinyl acetate copolymers, or mixtures thereof, as well as hybrids of these and other chemicals. In some embodiments, the binder is a binder suitable for use in interior wall paints. In some embodiments, the binder is a binder suitable for use in exterior paints. In some embodiments, the binder is a binder suitable for use in waterproof paints including one-component waterproof paints and / or two-component paints.

[0023] The average particle size of the polymer particles in the dispersion is not particularly critical and is advantageously from 40 nm to 1000 nm, preferably from 50 nm to 600 nm. The particle size herein is measured by a Zetasizer Nano ZS from Malvern Panalytical Ltd.

[0024] Aqueous coating composition In some embodiments, the aqueous coating composition of the present invention comprises (a) a binder and (d) a film-forming aid according to Formula 1 above. In some embodiments, the aqueous coating composition of the present invention comprises (a) a binder, (b) optionally, a pigment, (c) water, (d) a film-forming aid according to Formula 1 above. In some embodiments, the aqueous coating composition of the present invention comprises (a) a binder, (b) optionally, a pigment, (c) water, (d) a film-forming aid according to Formula 1 above, (e) one or more nonionic surfactants. In some embodiments, the aqueous coating composition of the present invention comprises (a) a binder, (b) optionally, a pigment, (c) water, (d) a film-forming aid according to Formula 1 above, (e) one or more nonionic surfactants, (f) one or more of a thickener, a dispersant, and a filler.

[0025] Various embodiments of the aqueous coating composition of the present invention can be used in applications such as, for example, wall paints, floor coatings, ceiling paints, exterior paints, and window frame coatings.

[0026] The aqueous coating composition of the present invention can be prepared by techniques well known in the coating industry. For example, the preparation of the aqueous coating composition includes a grinding step. In the grinding step, a number of components of the aqueous coating composition, such as pigments, and other materials that may not be homogenized under low shear mixing and are selected to reduce the particle size, can be combined with water (e.g., via a mill under high shear conditions) for grinding and / or dispersing. In particular, other components such as defoamers and / or wetting agents can be utilized in the grinding step.

[0027] The grinding step can provide that the resulting particles have an average particle size of 0.1 μm to 100 μm. All individual values and subranges from 0.1 μm to 100 μm are included. For example, the resulting particles can have an average particle size from a lower limit of 0.1, 0.5, or 1.0 μm to an upper limit of 100, 75, or 50 μm.

[0028] Following the grinding stage, a let-down stage can be carried out. The composition obtained from the grinding stage (e.g., a number of ground and / or dispersed aqueous coating composition components) can be combined with the film-forming aid according to Formula 1 and the remaining components utilized to form the aqueous coating composition.

[0029] In addition to the aqueous polymer dispersion (including the binder), the film-forming aid according to Formula 1, and optional pigments, the aqueous coating composition can include, for example, conventional coating adjuvants such as wetting agents, extenders, emulsifiers, plasticizers, curing agents, buffers, neutralizing agents, rheology modifiers, surfactants, humectants, biocides, defoamers, UV absorbers, optical brighteners, light and / or heat stabilizers, biocides, chelating agents, dispersants, colorants, waxes, and water repellents.

[0030] In some embodiments, the aqueous coating composition disclosed herein may include a wetting agent, which may also be referred to as a surfactant and / or a dispersant. As used herein, "wetting agent" refers to a chemical additive that can reduce surface tension and / or improve the separation of the particles of the aqueous coating composition disclosed herein. Examples of wetting agents include, but are not limited to, alcohol ethoxylate wetting agents, polycarboxylate wetting agents, anionic wetting agents, zwitterionic wetting agents, nonionic wetting agents, and combinations thereof. Specific examples of wetting agents that may be used in some embodiments include, among others, sodium bis(tridecyl)sulfosuccinate, sodium di(2-ethylhexyl)sulfosuccinate, sodium dihexylsulfosuccinate, sodium dicyclohexylsulfosuccinate, sodium diamylsulfosuccinate, sodium diisobutylsulfosuccinate, disodium isodecylsulfosuccinate, disodium ethoxylated alcohol half ester of sulfosuccinic acid, disodium N-octylsulfosuccinamate, and sulfated ethoxylated nonylphenol. Examples of commercially available wetting agents include, among others, for example, ECOSURF™ EH-9 and TERGITOL™ NP-10 available from The Dow Chemical Company, SURFYNOL 104 available from Evonik, and BYK-346 and BYK-349 polyether-modified siloxanes both available from BYK.

[0031] The aqueous coating composition may include from 0.01 to 10 weight percent of a wetting agent, based on the total weight of the aqueous coating composition. All individual values and subranges from 0.01 to 10 weight percent are included. For example, the aqueous coating composition may include from a lower limit of 0.01, 0.1, 0.2, 1.0, or 2.0 weight percent to an upper limit of 10, 8, 7, 5, 4, or 3 weight percent of a wetting agent, based on the total weight of the aqueous coating composition.

[0032] The pigments can be selected from a wide range of materials known to those skilled in the art of coatings, including, for example, organic and inorganic coloring pigments. Examples of suitable pigments and extenders include titanium dioxide such as anatase-type and rutile-type titanium dioxide; zinc oxide; antimony oxide; iron oxide; magnesium silicate; calcium carbonate; aluminosilicate; silica; various clays such as kaolin and exfoliated clay; and lead oxide. It is also contemplated that the aqueous coating composition may contain opaque polymer particles such as, for example, ROPAQUE™ Opaque Polymers (available from The Dow Chemical Company). Also contemplated are encapsulated or partially encapsulated opacifying pigment particles; polymers or polymer emulsions adsorbed or bonded to the surface of pigments such as titanium dioxide, for example, EVOQUE™ polymers (available from The Dow Chemical Company); and hollow pigments containing one or more voids.

[0033] Titanium dioxide is a typical pigment used to achieve hiding in architectural paints.

[0034] The amount of pigment and extender in the aqueous coating composition varies from 0 to 85 pigment volume concentration (PVC), thereby encompassing coatings otherwise described in the art, for example, as transparent coatings, stains, flat coatings, satin coatings, semi-gloss coatings, gloss coatings, primers, textured coatings. The aqueous coating compositions herein explicitly include architectural, maintenance, and industrial coatings, caulking materials, sealants, and adhesives. The pigment volume concentration is calculated by the following formula: PVC (%) = (volume of pigment(s) + volume of extender(s) × 100) / (total dry volume of the paint).

[0035] The solid content of the aqueous coating composition may be from 10% to 70% by volume. The viscosity of the aqueous coating composition can be 50 KU to 200 KU when measured according to ASTM D562. In some embodiments, the viscosity of the aqueous coating composition can be 80 KU to 120 KU when measured according to ASTM D562. As is known to those skilled in the art, the viscosities suitable for different coating methods vary considerably.

[0036] The aqueous coating compositions disclosed herein can be utilized to form coatings. These coatings can be used in a number of different coating applications, particularly industrial coating applications, architectural coating applications, automotive coating applications, outdoor furniture coating applications, and the like.

[0037] In use, various embodiments of the aqueous coating composition of the present invention can typically be applied to substrates such as, for example, wood, metal, plastic, marine and civil engineering substrates, pre-painted or primed surfaces, weathered surfaces, and cementitious substrates such as, for example, concrete, plaster, and mortar.

[0038] Drying of the aqueous coating composition to provide a coating can proceed under ambient conditions such as, for example, 5°C to 35°C, or the coating can be dried at elevated temperatures such as, for example, above 35°C to 80°C.

[0039] Some embodiments of the present invention are described in detail in the following examples.

Examples

[0040] The following examples are presented to illustrate the present invention and should not be construed as limiting the scope of the present invention. All parts and percentages are by weight unless otherwise indicated.

[0041] Film-forming aid In the following examples, different film-forming aids are used. Two of the film-forming aids (film-forming aids 1 and 2 of the present invention) are film-forming aids according to Formula 1 and represent film-forming aids that can be used in embodiments of the aqueous coating composition of the present invention. Film-forming aids 1 and 2 of the present invention are prepared from the following formulations:

[0042]

Table 1

[0043]

Table 2

[0044] The film-forming aids of the present invention are obtained by reacting an alkylene oxide (specified above) with an initiator in the presence of a catalyst for the ring-opening polymerization of the alkylene oxide. The polymerization is carried out in a 2-liter reactor. For film-forming aid 1 of the present invention, the initiator is 2-ethylhexanol, and for film-forming aid 2 of the present invention, the initiator is n-butanol. The catalyst used for the polymerization is potassium hydroxide. The alkylene oxide is supplied to a reactor containing the drying initiator (2-ethylhexanol or n-butanol) and the catalyst at a temperature of 120°C. The polymerization is considered complete when the pressure in the reactor returns to approximately the same pressure as before the supply of the alkylene oxide. These products are neutralized with an acid such as acetic acid or phosphoric acid to avoid catalytic oxidation. Each of the film-forming aids of the present invention is a film-forming aid according to Formula I: X-O-(AO) m H (Formula 1) as the film-forming aid. Regarding the film-forming aid 1 ("IC-1") of the present invention, X is 2-ethylhexanol, AO is propylene oxide, and m has an average value of 5. The film-forming aid 1 of the present invention is pentapropylene glycol 2-ethylhexyl ether. Regarding the film-forming aid 2 ("IC-2") of the present invention, X is n-butanol, AO is a mixture of ethylene oxide and propylene oxide in a random order, and m has an average value of 6. The film-forming aid 2 of the present invention is polyalkylene glycol monobutyl ether.

[0045] For comparison, the comparative examples use conventional film-forming aids. Comparative film-forming aid A ("CC-A") is UCAR (trademark) Filmer IBT, which is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate commercially available from The Dow Chemical Company. Comparative film-forming aid B ("CC-B") is bis-dipropylene glycol n-butyl ether adipate. Comparative film-forming aid C ("CC-C") is triethylene glycol bis(2-ethylhexanoate). Comparative film-forming aid D ("CC-D") is polyalkylene glycol 2-ethylhexyl ether.

[0046] The characteristics of the film-forming aids are shown in Table 3 below:

[0047]

Table 3

[0048] Binder The binders used in the examples are RHOPLEX AC-630LOX ("Binder A"), an aqueous polymer dispersion (50 wt% solids; MFFT = 17 °C) containing an acrylic polymer commercially available from The Dow Chemical Company, and ROVACE (trademark) NUEVA 4838 ("Binder B"), an aqueous polymer dispersion (50 wt% solids; MFFT = 13 °C) containing a vinyl acrylic polymer commercially available from The Dow Chemical Company.

[0049] Binder - film - forming aid formulation As shown in Table 4, various formulations of film - forming aids and binders are prepared with film - forming aid fillings of 4 wt%, 6 wt%, 8 wt%, and 10 wt% based on the weight of the binder on a total solids basis:

[0050] [Table 4]

[0051] The minimum film - forming temperature (MFFT) of the above binder - film - forming aid blend and the volatile organic compound (VOC) content of the film - forming aid are measured using the test methods described at the end of the Examples chapter. The MFFT is the temperature at which the polymer forms a homogeneous and transparent film without cracking. The results are shown in Tables 5 and 6:

[0052] [Table 5]

[0053] [Table 6]

[0054] Except for comparative film - forming aid A, film - forming aid 1 of the present invention shows better performance (lower MFFT) than comparative film - forming aids B - D. Comparative film - forming aid A has a lower MFFT than film - forming aid 1 of the present invention, but comparative film - forming aid A has a very high VOC content, so it is not very desirable as a film - forming aid. Film - forming aid 2 of the present invention also shows good MFFT reduction efficiency, mainly due to the acrylic binder (binder A).

[0055] Preparation of paint formulations To evaluate the performance of the film-forming aid of the present invention against comparative film-forming aids, a paint formulation (type of aqueous coating composition) is prepared. Two paint formulations (standard formulation and premium formulation) are used, and each film-forming aid is evaluated with each formulation. The aqueous coating composition (paint formulation) prepared using the film-forming aid of the present invention is referred to as the coating composition of the present invention, and the aqueous coating composition (paint formulation) prepared using the comparative film-forming aid is referred to as the comparative coating composition.

[0056] Each of the coating composition of the present invention and the comparative coating composition is prepared as follows.

[0057] Standard formulation Add water to a 10-liter plastic beaker, and then add the specified dispersants (potassium tripolyphosphate and TAMOL™ 1124), and the wetting agent (TRITON™ CF-10) while stirring at about 400 rpm with a dispersion plate. Add titanium dioxide, and then add the defoamer (Foamaster 111) in turn. Add the pigment extender in the following order: Omyacarb 1, Omyacarb 5, and Glomax LL. Add the biocide, and then add the solvent (ethylene glycol). Slowly add the thickener (Natrosol 250 HBR) to the above mixture, and stir the mixture for 2 minutes. Add water to complete the dispersion of the materials. Increase the dispersion speed to 2000 rpm while the viscosity gradually increases.

[0058] To ensure a homogeneous dispersion, continue to disperse this mixture for 30 minutes or more until no particles larger than 50 μm are observed.

[0059] Add ROPAQUE™ Ultra, a polymeric pigment, to the formulation, and then add water and the defoamer (Foamaster 111).

[0060] Next, add the specified binder (ROVACE™ NUEVA 4838) to the mixture, followed by the addition of ammonia (28%) and water. Stir for 10 minutes at 1000 rpm using a small dispersion plate.

[0061] Next, while stirring for an additional 10 minutes, add the specified thickener and rheology modifier (ACRYSOL™ RM-5000, RM-725), biocide (Rozone 2000), and the remaining water to the mixture. Add the rheology modifier slowly to achieve a KU viscosity of 90.0 - 100.0 KU and a pH of 8.5 - 9.0 (adjusted with ammonia).

[0062] Finally, after fractionating into different parts, add the film-forming aid to the formulation.

[0063]

Table 7

[0064] Premium formulation Add water to a 10-liter plastic beaker, followed by the specified dispersant (TAMOL™ 2002), followed by the solvent (propylene glycol) and wetting agent (TRITON™ HW-1000) while stirring at approximately 400 rpm using a dispersion plate. Add titanium dioxide and then the defoamer (Foamaster 111) in order. Add the pigment extender in the following order: Omyacarb 5, Mistron Monomix, Glomax LL, and Celite 400. Add the biocides (Kathon LX 1.5% and Rozone 2000). Slowly add the thickener (Natrosol 250 HBR) to the above mixture and stir the mixture for 2 minutes. Add water to complete the dispersion of the materials, followed by the buffer solution (ammonia 28%). Increase the dispersion speed to 2000 rpm while the viscosity gradually increases.

[0065] To ensure a homogeneous dispersion, continue to disperse this mixture for 30 minutes or more until no particles larger than 50 μm are observed.

[0066] Add ROPAQUE™ Ultra, a polymeric pigment, to the formulation, followed by the addition of water and an antifoaming agent (Foamaster 111).

[0067] Next, add the specified binder (RHOPLEX™ AC-630LOX) to the mixture, followed by the addition of ammonia (28%). Stir for 10 minutes at 1000 rpm using a small dispersion plate.

[0068] Next, add the specified thickeners and rheology modifiers (ACRYSOL™ RM-5000, RM-725) to the mixture and stir for an additional 10 minutes. Add the rheology modifier slowly to achieve a KU viscosity of 90.0 - 100.0 KU and a pH of 8.5 - 9.0 (adjusted with ammonia).

[0069] Finally, after fractionating into different parts, add a film-forming aid to the formulation.

[0070]

Table 8

[0071] After preparing the standard formulation and the premium formulation, add the film-forming aids separately. Using each of the film-forming aids of the present invention and each of the comparative film-forming aids, prepare the standard formulation and the premium formulation. The film-forming aids are added in an amount that provides 10 weight percent of the film-forming aid based on the weight of the binder relative to the total solids. The standard formulation contained 0.9 weight percent of the film-forming aid based on the total coating weight. The premium formulation contained 1.6 weight percent of the film-forming aid based on the total coating weight.

[0072] The standard formulation and the premium formulation have the following properties:

[0073]

Table 9

[0074] The paint stability and scrub resistance of each formulation are measured. The paint stability is measured by the change in viscosity at medium shear rate (the "KU viscosity", Krebs units - KU) using a viscometer as further explained below, and the results are shown in Table 10. The scrub resistance is measured by the number of scrub cycles for removing the coating film in the presence of an abrasive paste as further explained below, and the results are shown in Table 11. The labels in the columns in Tables 10 and 11 refer to the film-forming aids used in the respective formulations.

[0075]

Table 10

[0076]

Table 11

[0077] Regarding paint stability, all formulations except those made using Comparative Film-Forming Aid D functioned well, and the ability to maintain the variation in KU below 10.0 units was demonstrated. This is important for paint formulators. If there is a large variation, the paint formulator may need to modify the formulation, for example, by adding more thickening agents to achieve the appropriate viscosity. As described above, the formulation made using Comparative Film-Forming Aid D had large variations, reaching 40 units in the premium formulation.

[0078] Regarding scrub resistance, the formulations made using Film-Forming Aid 2 of the present invention had an increased number of cycles compared to the formulations made using Comparative Film-Forming Aid C, while the other formulations maintained similar performance. The formulations manufactured using Comparative Film-Forming Aid 4 had poor performance mainly in terms of a decrease in MFFT and paint stability because the viscosity decreased excessively after its addition.

[0079] Test method Minimum film formation temperature The MFFT is generally measured using ASTM D2354-10 (2018). To evaluate the ability of a film-forming aid to lower the MFFT of an emulsion, mixtures of the film-forming aid at different concentrations in a pure emulsion are prepared. A specified weight of the emulsion is added to a glass flask and mechanically stirred at 500 rpm. The desired weight of the film-forming aid is added and the system is stirred for 5 minutes. Keep the flask closed until the moment of film application.

[0080] To ensure the stability of the temperature gradient, turn on the power of the MFFT instrument and the thermostat at least 2 hours before starting the experiment.

[0081] Lift the lid of the apparatus and clean the steel plate with ethanol. Place the polyester sheet on the steel plate and fix it with one of its short sides. Place a 75-μm film applicator with three reservoirs on the same edge of the sheet fixed to the steel plate. Add approximately 2 mL of the sample to each reservoir of the applicator and immediately cast three films. Return the lid.

[0082] After the film is completely dry (at least 20 minutes of drying time), lift the lid and record the position of the thermocouple on the polyester sheet. Remove the sheet from the apparatus and place it under a bright light on a dark background. Visually evaluate the integrity of the film. Consider the position where the film is no longer continuous or where the film begins to show cracks or opacity as the MFFT point. Report the temperature of the thermocouple associated with that position. Test each mixture of the film-forming aid and the emulsion in triplicate. The reported result is the average of the individual values.

[0083] Scrub resistance The scrub resistance of the formulation is measured according to NBR 14940.

[0084] Paint stability (KU viscosity) The paint stability of each formulation is evaluated using the KU viscosity measured according to ASTM D562.

[0085] VOC content The VOC content of the film-forming aid is measured using EPA method 24.

Claims

1. A binder and a film-forming aid represented by Formula 1: X-O-(AO) ｍ H (Formula 1) (wherein X is an alkyl group having 4 to 8 carbon atoms, AO is a mixture of ethylene oxide and propylene oxide in a block or random order, and m is 1 to 10, or wherein X is an alkyl group having 8 carbon atoms, AO is propylene oxide, and m is 1 to 10), an aqueous coating composition.

2. The coating composition according to claim 1, wherein the film-forming aid contains 20% by weight or less of ethylene oxide based on the weight of the film-forming aid.

3. The molecular weight (M ｗ ) of the film-forming aid is 200 to 500, and the coating composition according to claim 1 or claim 2.

4. The coating composition according to any one of claims 1 to 3, wherein the binder is an aqueous polymer dispersion containing an acrylic polymer, a styrene-acrylic copolymer, a vinyl acetate-acrylic copolymer, an ethylene-vinyl acetate copolymer, or a mixture thereof.

5. The coating composition according to claim 4, wherein the aqueous coating composition contains 5 to 70% by weight of the polymer dispersion based on the total weight of the aqueous coating composition.

6. The coating composition according to any one of claims 1 to 5, wherein the aqueous coating composition contains 1 to 20% by weight of the film-forming aid based on the weight of the binder on a total solids basis.

7. The coating composition according to any one of claims 1 to 6, wherein the film-forming aid has a VOC content of less than 15% when measured according to EPA Method 24.

8. The coating composition according to any one of claims 1 to 7, wherein the film-forming aid is represented by Formula 1: X - O - (AO) ｍ H (Formula 1) (wherein X is an alkyl group having 4 to 8 carbon atoms, AO is a mixture of ethylene oxide and propylene oxide in a block or random order, and m is 1 to 10).

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