JP7531880B2 - Aqueous matte coating composition - Google Patents

Description

The present invention relates to an aqueous matte coating agent that, when applied to a target surface, forms a matte coating film to coat and protect the surface.

Floor polishes and coatings are used to protect hard surfaces such as floors and walls made of various materials such as wood, synthetic resin, concrete, and marble, while maintaining their beauty. Floor polishes and coatings generally dry to form a coating film when applied to a target surface, and protect the surface. Among them, water-based floor polishes and coatings are popular due to their ease of use and excellent durability. For example, Patent Document 1 discloses a floor polish composition that is an emulsion polymer of an ethylenically unsaturated compound in an aqueous dispersion state and contains a zinc compound. Patent Document 2 discloses a floor coating composition that contains an aqueous dispersion of a specific acrylic polymer having a carboxyl group, an aqueous dispersion of a urethane polymer having a carboxyl group, and polycarbodiimide as a curing agent.

On the other hand, with the trend towards higher quality in recent years, there is a trend towards a preference for matte hard surfaces such as floors and walls, and for floor polishes and coatings used to protect such surfaces, there is a demand for products that form a matte coating rather than the high-gloss coatings that have traditionally been mainstream.

Conventionally, to form a matte coating film, a matte agent such as a non-water-dispersible organic polymer fine particle powder or fine silica powder was added, which created unevenness on the coating film surface and diffused visible light to create a matte finish. However, in this case, the coating film does not form a flat surface, which can result in an undesirable appearance and feel, as well as problems such as the coating being easily soiled.

In order to solve these problems, Patent Document 3 discloses a matte paint emulsion consisting of an emulsion of polymer particles containing a monomer derived from styrene, an emulsion of polymer particles containing a monomer derived from vinyl acetate, and a urethane resin emulsion. In this matte paint emulsion, several types of emulsions with poor compatibility are mixed together, causing phase separation during coating film formation, thereby forming an opaque, non-glossy coating film. However, the coating film formed in this way is relatively soft due to the vinyl acetate and has poor durability, and in some cases cannot be used for applications such as floors.

Patent No. 3942044 Patent No. 6592469 Patent No. 2968077

The present invention aims to provide a water-based floor polish or coating agent that is capable of forming a matte coating film that is durable and has a smooth surface.

As a result of intensive research aimed at solving the above problems, the inventors have found that an aqueous coating agent comprising an aqueous polymer having a weight-average molecular weight of 15,000 or more and an emulsion of an optional polymer can form a matte coating film with a flat, non-rough surface while retaining the durability required for a floor polish or coating agent.

The present invention is based on these findings and includes the following inventions.
[1] (A) an aqueous polymer having a weight average molecular weight of 15,000 or more;
(B) an emulsion of a polymer;
An aqueous coating agent which forms a coating film having a 60 degree specular gloss value reduced by 10 or more compared to a coating film formed using only (B).
[2] The aqueous coating agent according to [1], wherein the aqueous polymer (A) comprises one or more selected from the group consisting of polyvinyl alcohol, polyacrylates, cellulose and its derivatives, polysaccharides and its derivatives, and silica-based aggregates.
[3] The aqueous coating agent according to [1] or [2], wherein the polymer (B) comprises one or both of an acrylic polymer and a urethane polymer.
[4] The aqueous coating agent according to [3], wherein the polymer (B) is an acrylic polymer having a glass transition temperature of less than 70° C.
[5] The aqueous coating agent according to any one of [1] to [4], having a viscosity of 50 mPa·S (25° C.) or less.
[6] A method for matt-coating a target surface, comprising applying the aqueous coating agent according to any one of [1] to [5] in an undiluted form or diluted form to the target surface.

The present invention provides an aqueous coating agent capable of forming a durable matte coating film with a smooth, non-rough surface.

In the present invention, (A) "aqueous polymer" refers to a polymer that is water-soluble or uniformly dispersible in water, and examples of such polymers include those that are generally used as gelling agents, thickening agents, viscosifying agents, rheology control agents, thickening stabilizers, thickening agents, etc. Examples of such aqueous polymers include (but are not limited to) polyvinyl alcohol, polyacrylates, cellulose and its derivatives, polysaccharides and its derivatives, silica-based aggregates, etc.

More specifically, the "polyvinyl alcohol" may be a partially saponified type, an intermediately saponified type, or a fully saponified type, and may also be variously modified polyvinyl alcohols such as carboxyl group modified, acetoacetyl group modified, silanol modified, or cation modified. The "polyacrylic acid salt" may be an alkali metal salt of polyacrylic acid (e.g., sodium salt, potassium salt, etc.), an ammonium salt, an amine salt, etc. (not limited to these). The "cellulose and its derivatives" may be methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, or salts or chemically modified products thereof (not limited to these). Examples of "polysaccharides and derivatives thereof" that can be used include, but are not limited to, guar gum, cajibu bean gum, tara gum, tamarind seed gum, gum arabic, gum tragacanth, karaya gum, alginic acid, carrageenan, xanthan gum, gellan gum, curdlan, peritin, chitin, chitosan, chitosamine, and salts or modified forms of sodium alginate, propylene glycol alginate, modified starch (e.g., sodium starch glycolate, sodium starch phosphate, etc.). "Silica-based aggregates" refer to hydrophilic fumed silica, and commercially available products such as AEROSIL (registered trademark) can be used.

In the present invention, a single water-based polymer may be used, or one or more types of water-based polymers may be used in combination.

In the present invention, the aqueous polymer used has a weight average molecular weight of more than 13,200, for example, 15,000 or more. If the weight average molecular weight of the aqueous polymer is less than 15,000, the film (hereinafter referred to as the "coating film") formed by drying the aqueous coating agent applied to the target surface may not be sufficiently matte. Preferably, in the present invention, the aqueous polymer has a weight average molecular weight of 74,000 or more, 77,000 or more, or 83,000 or more. The upper limit of the weight average molecular weight of the aqueous polymer is not particularly limited, but can be, for example, 100,000,000 or less, preferably 10,000,000 or less. The "weight average molecular weight" described in this specification can be determined by gel permeation chromatography (GPC) or viscosity measurement of an aqueous solution.

The aqueous coating agent of the present invention can contain an amount of aqueous polymer that can sufficiently mattify the coating film. If the amount of aqueous polymer added is too small, a sufficient matt effect may not be obtained, while if the amount added is too large, the storage stability and water resistance of the aqueous coating agent may decrease, and the viscosity may become too high, making it difficult to use, or causing unevenness or irregularities on the coating film surface, which are undesirable. For example, the aqueous coating agent of the present invention can contain an amount of aqueous polymer selected from the range of 0.01 to 2.0 mass%, preferably 0.03 to 1.0 mass%, and more preferably 0.1 to 0.7 mass%, purely based on 100 mass% of the emulsion of the polymer (B).

In the present invention, (B) "polymer emulsion" means an aqueous dispersion of a polymer. The polymer may be one that has been conventionally used as a base agent for floor polishes and floor coatings, and is not particularly limited, but examples thereof include acrylic polymers and urethane polymers. In addition, emulsions of polyester polymers, epoxy polymers, silicone polymers, fluorine polymers, etc. may also be used as (B) "polymer emulsion" of the present invention. One or a combination of a number of polymers selected from these may be used.

The "acrylic polymer" may be one that has been generally used as a base agent for floor polishes and floor coatings. In particular, the glass transition temperature (hereinafter referred to as "Tg") of the acrylic polymer is preferably less than 70°C, more preferably 5 to 65°C, and even more preferably 10 to 60°C. By using such a polymer, it is possible to impart durability to the coating film that is formed without adding an excessive amount of plasticizers or film-forming assistants for film formation. If the Tg of the acrylic polymer exceeds 70°C, the coating film may become hard and brittle, and may have poor followability when applied to a target surface (e.g., a floor surface). Furthermore, if the Tg is less than 5°C, blocking (stickiness) may occur in the coating film. The "Tg" of the acrylic polymer can be calculated using a conventionally known method (i.e., the Fox formula). Such an acrylic polymer can be obtained by copolymerizing at least one acrylic monomer having a carboxyl group and at least one acrylic monomer not having a carboxyl group in an appropriate combination. Alternatively, it is possible to combine a part of the acrylic monomer with other polymerizable unsaturated monomers. In addition, among the other polymerizable unsaturated monomers, a monomer having a carboxyl group may be used.

Examples of "acrylic monomers having a carboxyl group" include acrylic acid, methacrylic acid, etc.

Examples of the "acrylic monomer having no carboxyl group" include acrylic acid esters and methacrylic acid esters such as methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, isopropyl methacrylate, isopropyl acrylate, n-butyl methacrylate, n-butyl acrylate, isobutyl methacrylate, isobutyl acrylate, octyl methacrylate, octyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, lauryl methacrylate, lauryl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, hydroxypolyoxyethylene methacrylate, hydroxypolyoxyethylene acrylate, hydroxypolyoxypropylene methacrylate, hydroxypolyoxypropylene acrylate, hydroxypolyoxybutylene methacrylate, hydroxypolyoxybutylene acrylate, vinyl methacrylate, vinyl acrylate, allyl methacrylate, and allyl acrylate. Other examples of "acrylic monomers without a carboxyl group" include acrylic monomers with an aliphatic ring structure such as cyclohexyl methacrylate, cyclohexyl acrylate, isobornyl methacrylate, and isobornyl acrylate, and acrylic monomers with an aromatic ring structure such as benzyl methacrylate and benzyl acrylate.

Examples of "other polymerizable unsaturated monomers" having a carboxyl group include crotonic acid, itaconic acid, fumaric acid, maleic acid, monomethyl itaconate, monomethyl fumarate, monobutyl fumarate, citraconic acid, maleic anhydride, etc. Other examples of "other polymerizable unsaturated monomers" that do not have a carboxyl group include dienes such as butadiene, chloroprene, and isoprene; vinyl esters such as vinyl acetate; vinyl chloride, vinylidene chloride, methacrylonitrile, acrylonitrile, and N-vinylpyrrolidone, styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 2-hydroxymethylstyrene, 4-ethylstyrene, 4-ethoxystyrene, 3,4-dimethylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chloro-3-methylstyrene, 4-t-butylstyrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene, 1-vinylnaphthalene, and divinylbenzene.

The "acrylic polymer" can be prepared by polymerizing the above-mentioned monomers by emulsion polymerization using an emulsifier and a polymerization initiator in accordance with a conventionally known method (e.g., Japanese Patent No. 6592469). The acrylic polymer has a weight average molecular weight of 100,000 or more, for example, 300,000 or more.

The acid value of the acrylic polymer is preferably 30 to 160, more preferably 50 to 150. If the acid value of the acrylic polymer is lower than the above range, the density of the carboxyl groups for crosslinking will be low, and the durability of the coating film may be impaired. On the other hand, if the acid value is higher than the above range, the water-based coating agent may have poor conformability when applied to a target surface (e.g., a floor surface). The "acid value" is measured by dissolving a sample in a titration solvent made of a mixture of xylene and dimethylformamide (1/1, volume ratio) and titrating it with a 0.1 mol/L potassium hydroxide-ethanol solution by potentiometric titration, with the inflection point on the titration curve being the end point (neutralization point). The acid value can then be calculated from the titration amount of the potassium hydroxide-ethanol solution up to the end point.

The "urethane-based polymer" may be one that has been commonly used as a base agent in floor polishes and floor coatings. Such a urethane-based polymer may be one obtained by reacting a polyol with a polyisocyanate in accordance with a conventionally known method (e.g., Japanese Patent No. 6592469). The weight-average molecular weight of the urethane-based polymer is preferably 3,000 to 200,000, and more preferably 3,000 to 100,000.

Examples of "polyols" include polyester polyols, polycarbonate polyols, polyether polyols, and alkylene oxide adducts of bisphenols, which may be used alone or in combination of two or more. Among these, polyols without aromatic rings are preferred because they are less likely to discolor during production or after the passage of time.

The polyester polyol is obtained by an esterification reaction between a polycarboxylic acid and a polyhydric alcohol. Among the polycarboxylic acids, examples of those that do not have an aromatic ring include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, maleic acid, pimelic acid, suberic acid, azelaic acid, itaconic acid, sebacic acid, chlorendic acid, 1,2,4-butane-tricarboxylic acid, decanedicarboxylic acid, cyclohexanedicarboxylic acid, dimer acid, and fumaric acid, or esters thereof. These polycarboxylic acids or esters thereof may be used alone or in combination of two or more.

The polyol is preferably a polyol having a hydrophilic group. Examples of the hydrophilic group include an anionic group, a cationic group, and a nonionic group. A polyol having at least a carboxyl group as a hydrophilic group is preferably used. Examples of polyols having a carboxyl group as a hydrophilic group include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and 2,2-dimethylolvaleric acid. Among these, 2,2-dimethylolpropionic acid is preferred. In addition, polyester polyols having a carboxyl group obtained by reacting the above-mentioned polyol having a carboxyl group with a polyvalent carboxylic acid can also be used.

Examples of "polyisocyanates" include aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate; cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate; and these may be used alone or in combination of two or more.

"Polyester polymers" are polymers obtained by reacting polycarboxylic acids with polyalcohols, and examples thereof include polyethylene terephthalate, polylactic acid, and commercially available products such as "Elitel KT-8803" (manufactured by UNITIKA), "Pesresin A-645GH" (manufactured by Takamatsu Oil Co., Ltd.), and "Vylonal MD-2000" (manufactured by Toyobo Co., Ltd.), but are not limited to these.

An "epoxy polymer" is a polymer of a compound containing two or more epoxy groups in the molecule, and examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, diglycidyl ether of bisphenol A/F, N,N-diglycidylaniline, polyglycol diglycidyl ether, and the commercially available "ADEKA Resin EM Series" (manufactured by ADEKA Corporation), but are not limited to these.

"Silicon-based polymers" are polymers that have a siloxane bond consisting of silicon and oxygen as a backbone, with organic groups, mainly consisting of methyl groups, bonded to the silicon. They also include polymers with reactive alkoxysilane groups introduced into the side chains. For example, a commercially available product is "ATW-008S" (manufactured by Taisei Fine Chemical Co., Ltd.), but is not limited to these.

"Fluorine-based polymers" are polymers obtained by polymerizing olefins that contain fluorine. Examples of fluorine-based polymers include polytetrafluoroethylene, perfluoroalkoxyalkanes, ethylene-tetrafluoroethylene copolymers, perfluoroethylene-propene copolymers, polyvinylidene fluoride, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymers, and commercially available products such as "Lumiflon FE-4500" (manufactured by AGC Inc.), but are not limited to these.

The polymer emulsion of the present invention can contain the polymer in an amount of 10 to 90% by weight, preferably 20 to 70% by weight, in terms of solids concentration.

The aqueous coating agent of the present invention may further contain a curing agent (also called a "crosslinking agent"), if necessary.

The curing agent reacts with the above-mentioned polymer to form a complex three-dimensional crosslinked structure, which contributes to the formation of the coating film. Any curing agent capable of crosslinking the above-mentioned polymer may be used, for example, polycarbodiimide, polyisocyanate, polyvalent metal compound, etc. Examples of polycarbodiimide that can be used include aromatic polycarbodiimides such as poly(4,4'-diphenylmethanecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(diisopropylphenylcarbodiimide), and poly(triisopropylphenylcarbodiimide); alicyclic polycarbodiimides such as poly(dicyclohexylmethanecarbodiimide), and aliphatic polycarbodiimides such as poly(diisopropylcarbodiimide). Examples of polyisocyanates include aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, xylylene diisocyanate, and tetramethyl xylylene diisocyanate; cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate. These may be used alone or in combination of two or more. The polyvalent metal compound is a compound containing a divalent or higher metal, specifically, a polyvalent metal such as beryllium, magnesium, calcium, strontium, iron, cobalt, nickel, zinc, manganese, copper, cadmium, lead, bismuth, barium, antimony, and zirconium. For example, zinc oxide, calcium oxide, calcium hydroxide, aluminum hydroxide, zinc ammonia carbonate, calcium ethylenediamine carbonate-ammonia, zinc acetate ammonia, zinc acrylate ammonia, zinc malate ammonia, and calcium alanine ammonia can be used.

The aqueous coating agent of the present invention may contain a hardener in an amount of 0.5 to 25% by weight based on 100% by weight of the above-mentioned polymer.

The polymer emulsion of the present invention may further contain a plasticizer, an alkali-soluble resin, a slip control agent, a film-forming aid, and a wettability improver, as necessary.

Examples of plasticizers that can be used include citric acid esters such as acetyl tributyl citrate, phosphate esters such as tributoxyethyl phosphate, aliphatic dibasic acid esters such as dibutyl adipate, isobutyl ester derivatives of pentanediol, and chlorinated paraffin.

Examples of alkali-soluble resins that can be used include diisobutylene-maleic anhydride copolymer, rosin-modified maleic acid, styrene-maleic acid copolymer, (meth)acrylic acid ester-(meth)acrylic acid polymer, styrene-(meth)acrylic acid copolymer, and shellac.

Examples of slip control agents that can be used include vegetable waxes such as candelilla wax, carnauba wax, rice wax, wood wax, and jojoba oil; animal waxes such as beeswax, lanolin, and whale wax; mineral waxes such as montan wax, ozokerite, and ceresin; petroleum waxes such as paraffin wax, microcrystalline wax, and petrolatum; synthetic hydrocarbon waxes such as Fischer-Tropsch wax; synthetic waxes such as (oxidized) polyethylene wax and (oxidized) polypropylene wax; and emulsions thereof.

Examples of film-forming aids that can be used include alcohols such as ethanol, polyhydric alcohols such as ethylene glycol, glycol ethers such as diethylene glycol monomethyl ether and diethylene glycol monoethyl ether, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB), and Texanol.

As wettability enhancers, fluorosurfactants, silicon-based surfactants, anionic surfactants, fatty acid esters, fatty acid alkanolamides, nonionic surfactants, and amphoteric surfactants can be used.

The polymer emulsion of the present invention may further contain other ingredients, such as a pH adjuster such as ammonia, a preservative, an antifoaming agent, an antibacterial agent, a fragrance, a dye, colloidal silica, a fluorescent brightener, and an ultraviolet absorber, as necessary.

The aqueous coating agent of the present invention can be obtained by mixing the aqueous polymer and polymer emulsion described above, and the other components described above. When mixing, the order of adding and mixing each component is not particularly limited, and all components may be added and mixed at the same time, or each component may be added and mixed individually or in any combination in multiple batches.

The aqueous coating agent of the present invention preferably has a viscosity at 25°C of 50 mPa·S or less, more preferably 20 mPa·S or less, and even more preferably 12 mPa·S or less. If the viscosity of the aqueous coating agent at 25°C exceeds 50 mPa·S, the application feel and spread of the agent on the target surface may be poor, which may result in a failure to obtain a smooth coated surface or a decrease in work efficiency. The viscosity of the aqueous coating agent of the present invention can be adjusted to a desired value by increasing or decreasing the amount of the aqueous polymer blended. The viscosity of the aqueous coating agent can be measured by the method described in detail in the Examples.

The aqueous coating agent of the present invention can form a matte coating film by applying it to a target surface and drying it. In the present invention, "matte" means that the 60-degree specular gloss value of the coating film formed is 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, or 90 or more lower than that of a coating film formed only with an emulsion of the polymer (B) without containing the aqueous polymer (A). In general, when the 60-degree specular gloss is 50 or less, it can be judged that there is no gloss or that the gloss is suppressed. For example, when the 60-degree specular gloss is about 50, it is also called "5-part gloss" or "semi-matte", and in particular, when it is 10 or less, it is called "matte" or "full matte". On the other hand, when the gloss is high, it is called "glossy" or "full gloss". The matte coating film in the aqueous coating agent of the present invention can be matted by increasing or decreasing the amount of the aqueous polymer without significantly decreasing the basic coating film performance, thereby achieving the desired low gloss. The 60-degree specular gloss of the coating film formed by the aqueous coating agent can be measured by the method detailed in the Examples.

The aqueous coating agent of the present invention can be applied to hard surfaces such as floors and walls made of various materials, including vinyl, plastic, stone, cement, and wood.

The aqueous coating agent of the present invention can be applied to the target surface by conventional methods such as spray application, roller application, brush application, paint brush application, and mop application. In this application process, the aqueous coating agent of the present invention can be used as is or diluted with an appropriate solvent such as water or a water-miscible solvent. Other application conditions such as temperature and humidity can be adjusted appropriately using a dryer, fan, air conditioner, etc.

The aqueous coating agent of the present invention applied to the target surface typically dries at 5 to 35°C, more preferably 15 to 30°C, to form a coating film that coats and protects the target surface. In the process of forming the coating film, either a blowing means or a heating means, or both, can be used as appropriate to promote evaporation of water. This makes it easier to adjust the time for coating film formation, but the heating means is only for the purpose of evaporating water, and heating is not a necessary component for coating film formation.

The coating film of the aqueous coating agent of the present invention obtained in this manner is, as described above, non-glossy or has a matte finish with reduced gloss.

The aqueous coating agent of the present invention will be described in detail below with reference to examples and comparative examples. Note that the present invention is not limited to these.

I. Materials 1. Water-based polymer Polyvinyl alcohol (PVA)
(1) JP18: Nippon Vinyl Acetate & Poval Co., Ltd., partially saponified PVA (saponification degree 87.0-89.0 mol%), polymerization degree 1,700 (weight average molecular weight 83,400), used as a 10% aqueous solution.
(2) JF17L: Japan Vinyl Acetate & Poval Co., Ltd., fully saponified PVA (saponification degree 98.0-99.0 mol%), polymerization degree 1,700 (weight average molecular weight 74,800), used as a 10% aqueous solution.
(3) JC33: Japan Vinyl Acetate & Poval Co., Ltd., fully saponified PVA (saponification degree 99.0 mol % or more), polymerization degree 3,300 (weight average molecular weight 145,200), used as a 10% aqueous solution.
(4) JC40: Japan Vinyl Acetate & Poval Co., Ltd., fully saponified PVA (saponification degree 99.0-99.5 mol%), polymerization degree 4,000 (weight average molecular weight 176,000), used as a 5% aqueous solution.
(5) JP45: Nippon Vinyl Acetate & Poval Co., Ltd., partially saponified PVA (saponification degree 86.5-89.5 mol%), polymerization degree 4,500 (weight average molecular weight 220,700), used as a 5% aqueous solution.
(6) JC25: Japan Vinyl Acetate & Poval Co., Ltd., fully saponified PVA (saponification degree 99.0 mol% or more), polymerization degree 2,500 (weight average molecular weight 110,000), used as a 10% aqueous solution.
・Polyacrylic acid polymer (PAA)
(7) Ammonium polyacrylate: A-30: Toagosei Co., Ltd., weight average molecular weight 100,000, used as a 30% aqueous solution.
Hydroxypropyl methylcellulose (HPMC)
(8) Celny L: Nippon Soda Co., Ltd., weight average molecular weight 140,000, used as a 5% aqueous solution.

2. Comparative Polymers a) Low molecular weight aqueous polymer JF03: Japan Vinyl Acetate & Poval Co., Ltd., fully saponified PVA (saponification degree 98.0-99.0 mol%), polymerization degree 300 (weight average molecular weight 13,200), used as a 5% aqueous solution.
a) Non-water-dispersible organic polymer fine particle powder: Polymethyl methacrylate (PMMA)
Tuftic AR750SQ: Nippon Exlan Kogyo Co., Ltd., organic spherical fine particles having an average particle size of 18 μm, added in the form of powder.
Tuftic AR750SSQ: Nippon Exlan Kogyo Co., Ltd., organic spherical fine particles having an average particle size of 8 μm, added in the form of powder.

3. Polymer Emulsions As emulsions containing polymers, emulsions A to E were used with the compositions shown in Table 1 below, which are based on the conventionally known standard floor polishes (e.g., Japanese Patent No. 6592469, Japanese Patent No. 3942044, etc.). The amount of each component in the table is shown in mass%, and the numbers in parentheses next to the raw material names indicate the solids concentration (%). The amount of each component in the table is shown in its actual form.

The raw materials used in the table are as follows:

II. Test Method and Results Aqueous coating agents of Examples 1 to 43 and Comparative Examples 1 to 9 were prepared with the compositions shown in Tables 3-1 to 3-5 below, and their viscosity, 60-degree specular gloss, appearance, and water resistance were evaluated. The results are shown in Tables 3-1 to 3-5. The amount (mass) of each component in the tables indicates the mass of the (B) emulsion as 100 mass%, to which the (A) aqueous polymer was added at a specified ratio. The amount of the (A) aqueous polymer is shown as a pure content.

The test methods and evaluation criteria for each item are as follows:
[viscosity]
The viscosity of each aqueous coating agent at 25° C. was measured in accordance with JIS K-3920 (floor polish test method) using a single cylinder viscometer, spindle #1, with guard, 60 rpm, and 1 minute.
<Evaluation criteria>
The measured values were judged as follows:
◎: 12 mPa·S or less 〇: 20 mPa·S or less △: 50 mPa·S or less ×: Over 50 mPa·S

[water resistance]
Water resistance was evaluated according to JIS K-3920 (floor polish test method). That is, a specified composition vinyl floor tile (KT) was used as a test substrate, which was washed and dried. The test substrate was placed horizontally, and an aqueous coating agent was transferred to it in an amount of 10±2 mL/ ^m2 , and spread evenly with medical gauze. After the first application, the coating was dried for 30 minutes or more, and then a second application was applied, and a third application was applied in the same manner. The specimens were used after 24 hours had passed since application.

0.1 mL of water was dropped onto the center of the test piece, which was then covered with a Petri dish and left to stand for 1 hour. The Petri dish was then removed, and any water remaining on the test piece was absorbed with a soft cloth or the like. The test piece was then left to stand for 1 or 2 hours, and the state of whitening of the test piece was visually determined.
<Evaluation criteria>
◎: No whitening (high water resistance)
○: Slight whitening (slightly noticeable when visually observed from a distance of 30 cm)
△: Slight whitening (slightly noticeable when viewed from 2m away)
×: Whitening phenomenon occurred (no water resistance. Clearly visible when viewed from 2 m away)

[60 degree specular gloss]
The 60-degree specular gloss was evaluated in accordance with JIS K-3920 (Floor Polish Testing Method). That is, the gloss of the test piece was measured by measuring the reflectance when the incident angle and receiving angle were 60°, and expressed as a percentage with the gloss of the reference surface of the specular gloss taken as 100.
<Evaluation criteria>
◯: Decreased by 10 or more compared to the measured value obtained when only the same emulsion was included. ×: Decreased by less than 10 or no decrease compared to the measured value obtained when only the same emulsion was included.

[Coating film appearance]
The appearance of the test pieces was judged visually.
<Evaluation criteria>
◯: No roughness or unevenness is observed △: Unevenness in the paint streaks is observed ×: Roughness or unevenness is observed

As shown by the above results, it was confirmed that by adding an aqueous polymer to an emulsion containing a polymer, it is possible to matte the coating film without impairing the properties required for floor polish, such as viscosity and water resistance.

In addition, unlike the matte finish created by conventional matting agents such as finely powdered silica, no irregularities or unevenness were found on the coating surface (visually), and it was confirmed that a smooth surface could be formed without any roughness.

On the other hand, when non-water-dispersible organic polymer microparticle powder was added in an amount necessary to achieve a gloss level of 50 or less (Comparative Example 8, Comparative Example 9), a matte coating film was formed when applied, but the surface was uneven and felt rough, and a satisfactory smooth surface was not obtained.

It was also confirmed that even if the polymer was water-based, if the molecular weight was small (Comparative Example 5, Comparative Example 6), the matte effect of the coating film could not be obtained.

Claims (5)

(A) an aqueous polymer having a weight average molecular weight of 15,000 or more;
(B) an emulsion of a polymer;
The present invention is characterized in that a coating film having a 60 degree specular gloss value reduced by 10 or more compared to a coating film formed by only (B),
(A) An aqueous coating agent, wherein the aqueous polymer comprises one or more selected from the group consisting of polyvinyl alcohol, and polysaccharides and derivatives thereof. The aqueous coating agent according to claim 1, wherein the polymer (B) includes one or both of an acrylic polymer and a urethane polymer. The aqueous coating agent according to claim 2, wherein the polymer (B) is an acrylic polymer having a glass transition temperature of less than 70°C. The aqueous coating agent according to any one of claims 1 to 3, having a viscosity of 50 mPa·S (25°C) or less. A method for matt-coating a target surface, comprising applying the aqueous coating agent according to any one of claims 1 to 4, either undiluted or diluted, to the target surface.