Water-based coating composition

Abstract

To provide an aqueous coating composition having excellent stain resistance and elastic suitability.SOLUTION: There is provided an aqueous coating composition which comprises: a core / shell emulsion (A) in which the core is a polymer having a glass transition temperature of 5 to 60°C and the shell is a polymer having a glass transition temperature of 50 to 100°C in which ΔTg (the glass transition temperature of the shell-the glass transition temperature of the core) is 30 to 60°C; and at least one crosslinking agent (B) selected from a hydrazide compound, a glycidyl group-containing compound, a carbodiimide compound, an oxazoline compound and an isocyanate compound.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Conventionally, paints have been applied to outdoor substrates typified by buildings for the purpose of decoration or protection. Generally, due to long-term exposure outdoors, the coating film surface is likely to be soiled by dust, iron powder, rain (acid rain), sunlight, etc., and the appearance of the coating film deteriorates.

[0003] As one direction of the market in the field of architectural paints regarding such problems, there is a market need for paints having stain prevention characteristics due to dripping rain, so-called low-pollution paints.

[0004] On the other hand, in recent years, there has been a conversion to water-based in the paint field. Generally, water-based paints tend to have inferior performance such as finish and water resistance compared to solvent-based paints due to hydrophilic groups, emulsifiers, etc. However, with the recent market needs, the development of water-based paints that have good finish and water resistance and further form a coating film that exhibits high functions such as stain resistance is desired.

[0005] As methods for imparting stain resistance to a coating film, a method of making the coating film water-repellent and a method of making it hydrophilic are known, and a paint designer can select either method according to the type and properties of the object to be coated and the stain components that can adhere to it.

[0006] For example, Patent Document 1 discloses an aqueous paint composition containing a water-soluble acrylic resin containing a tertiary amino group and a carbonyl group, a carbonyl group-containing acrylic emulsion, and a hydrazide compound.

[0007] According to such an aqueous paint composition, a coating film excellent in stain resistance can be formed. Moreover, since the water-soluble acrylic resin containing a tertiary amino group and a carbonyl group reacts with the hydrazide compound which is a curing agent and the acrylic emulsion containing a carbonyl group as a binder component, the stain resistance can be maintained for a long period of time. However, it cannot be denied that the water resistance and weather resistance of the coating film formed under normal temperature drying conditions are insufficient.

[0008] In addition, the coating film applied to the outdoor base material is required to have appropriate flexibility (hereinafter may be referred to as "elastic adaptability" in this specification) so as to follow the cracks on the base material surface.

[0009] For example, in Patent Document 2, after applying a substrate conditioner (I) containing a copolymer aqueous dispersion (A) having a glass transition temperature of the copolymer of -20°C or lower to the surface to be coated, on the coating surface, a copolymer aqueous dispersion (B) having a glass transition temperature of the copolymer of -60 to 0°C and a copolymer aqueous dispersion (C) having a glass transition temperature of the copolymer of 15 to 50°C are contained in a solid content mass ratio of (B) / (C) ratio of 20 / 80 to 80 / 20. A coating finishing method characterized by applying a topcoat paint (II) is disclosed.

[0010] However, such a coating finishing method is limited to the case where a substrate conditioner containing a copolymer aqueous dispersion having a low glass transition temperature is used. Also, although it is good when the substrate surface is smoothly adjusted, it is not sufficient when the substrate surface is adjusted to an uneven shape such as a wavy shape. It has not met the current requirements for a topcoat paint that can be applied to various types and shapes of substrate conditioners and substrate surfaces, that is, a topcoat paint excellent in elastic adaptability.

Patent Document 1

Patent Document 2

Disclosure of the Invention

Problems to be Solved by the Invention

[0011] An object of the present invention is to provide an aqueous paint having both low pollution property and elastic suitability.

Means for Solving the Problems

[0012] To achieve the above object, the present invention includes the subject matters described in the following items. Item 1. The core is a polymer having a glass transition temperature of 5 to 60 ° C, The shell is a polymer having a glass transition temperature of 50 to 100 ° C, A core / shell emulsion (A) in which ΔTg (glass transition temperature of the shell - glass transition temperature of the core) is 30 to 60 ° C, and An aqueous paint composition characterized by containing at least one crosslinking agent (B) selected from hydrazide compounds, glycidyl group-containing compounds, carbodiimide compounds, oxazoline compounds and isocyanate compounds. Item 2. The aqueous paint composition according to Item 1 above, wherein the mass ratio of the core polymer to the shell polymer in the core / shell emulsion (A) is in the range of 50 / 50 to 90 / 10 in the ratio of the former / latter. Item 3. The solid content of the core / shell emulsion (A) is 30 to 99.5 parts by mass based on 100 parts by mass of the solid content of the aqueous paint composition, the aqueous paint composition according to Item 1 or 2 above. Item 4. The aqueous paint composition according to any one of Items 1 to 3 above, further containing 20 to 200 parts by mass of titanium oxide pigment (C) based on 100 parts by mass of the solid content of the aqueous paint composition. Item 5. The aqueous paint composition according to any one of Items 1 to 4 above, further containing 3 to 15 parts by mass of an organic solvent (D) having a boiling point of 200 ° C or higher based on 100 parts by mass of the solid content in the aqueous paint composition. Item 6. ​A cured coating film with a thickness of 70 μm was formed on a glass plate with a thickness of 3.0 mm, and the Martens hardness measured at a temperature of 23°C and a load of 5 mN / 25 s using an ultra-micro hardness tester on the coating film surface when cured for 1 week in an atmosphere of 23°C and 50% humidity is 2.0 to 40.0 N / mm 2 The aqueous coating composition according to any one of the above items 1 to 5, which can form a coating film having the above properties. Item 7. A coating film forming method comprising the step of coating an object to be coated with the aqueous coating composition according to any one of the above items 1 to 6. Item 8. A coated article on which a cured coating film formed from the aqueous coating composition according to any one of the above items 1 to 6 is formed.

Advantages of the Invention

[0013] According to the aqueous coating composition of the present invention, a coating film having low contamination and appropriate elasticity can be formed.

Modes for Carrying Out the Invention

[0014] Hereinafter, the aqueous coating composition of the present invention will be described in more detail.

[0015] The aqueous coating composition of the present invention contains a core / shell emulsion (A) in which the core is a polymer having a glass transition temperature of 5 to 60°C and the shell is a polymer having a glass transition temperature of 50 to 100°C, and ΔTg (glass transition temperature of the shell - glass transition temperature of the core) is 30 to 60°C, and at least one crosslinking agent (B) selected from hydrazide compounds, glycidyl group-containing compounds, carbodiimide compounds, oxazoline compounds and isocyanate compounds.

[0016] Core / Shell Emulsion (A) The core / shell emulsion (A) used in the present invention, from the viewpoint of the low contamination and elastic suitability of the resulting coating film, has a core made of a polymer having a glass transition temperature of 5 to 60°C, preferably 10 to 50°C, more preferably 10 to 40°C, and a shell made of a polymer having a glass transition temperature of 50 to 100°C, preferably 60 to 90°C, more preferably 65 to 85°C, and ΔTg (glass transition temperature of the shell - glass transition temperature of the core) is 30 to 60°C, preferably 35 to 60°C, more preferably 40 to 60°C.

[0017] A core / shell emulsion is multi-layered structured particles composed of a central layer and an outer shell layer. It is also possible to form another layer between the two layers.

[0018] The core / shell emulsion is synthesized by a seed emulsion polymerization method or a multi-stage emulsion polymerization method. For example, in the case of two-layer structured particles, first, a first-stage polymerizable unsaturated monomer (a mixture of one or more kinds) that forms a resin having a glass transition temperature of 5 to 60°C is subjected to emulsion polymerization to prepare seed particles, and then in the presence of the seeds, a second-stage polymerizable unsaturated monomer (a mixture of one or more kinds) that forms a resin having a glass transition temperature of 50 to 100°C is supplied and subjected to emulsion polymerization, whereby a core / shell emulsion is obtained. In the case of particles composed of three or more layers, in the middle of the above first-stage and second-stage processes, a process of supplying a polymerizable unsaturated monomer (a mixture of one or more kinds) that forms another resin layer and subjecting it to emulsion polymerization is added.

[0019] In addition, in this specification, when the absolute temperature of the glass transition temperature Tg (°C) of each copolymer is defined as Tg”, it can be calculated as follows. 1 / Tg” = W1′ / T1 + W2′ / T2 ··· + Wn′ / Tn (In the formula, W1′, W2′ ··· Wn′ are the weight fractions of each monomer with respect to the total monomers used in the production of the copolymer, and T1, T2, ··· Tn represent the glass transition temperatures (absolute temperatures) of the homopolymers of each monomer.).

[0020] From the viewpoints of low fouling property and elastic suitability of the resulting coating film, the mass ratio of the polymer of the core to the polymer of the shell is preferably in the range of 50 / 50 to 90 / 10, more preferably 50 / 50 to 80 / 20, and still more preferably 50 / 50 to 70 / 30, in terms of the ratio of the former to the latter.

[0021] From the viewpoints of low fouling property and elastic suitability of the resulting coating film, the particle diameter of the core / shell emulsion is in the range of 100 to 1000 nm, preferably 100 to 500 nm, and more preferably 100 to 300 nm. Outside this range, the elastic suitability is poor, which is not desirable.

[0022] In this specification, the particle diameter of the core-shell emulsion is the value measured at 20 °C after dilution with deionized water using a submicron particle size distribution measuring device "COULTER N4 type" (manufactured by Beckman Coulter, Inc.).

[0023] Specific examples of the above-mentioned polymerizable unsaturated monomers include, for example, aromatic monovinyl compounds such as styrene, ethylvinylbenzene, α-methylstyrene, fluorostyrene; vinyl cyanide compounds such as acrylonitrile, methacrylonitrile; acrylate monomers such as methyl acrylate, ethyl acrylate, n,i,tert-butyl acrylate, 2-ethylhexyl acrylate, β-acryloyloxyethyl hydrogen phthalate, 2-hydroxyethyl acrylate, diacetone acrylamide, 2-acryloyloxy-2-hydroxyethyl phthalic acid, 2-hydroxy-3-phenoxypropyl acrylate, glycidyl acrylate, N,N-dimethylaminoethyl acrylate; methacrylate monomers such as methyl methacrylate, ethyl methacrylate, n,i,tert-butyl methacrylate, 2-ethylhexyl methacrylate, methoxydiethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, 2-methacryloyloxy-2-hydroxypropyl phthalate, 2-hydroxyethyl methacrylate, diacetone methacrylamide, cyclohexyl methacrylate, glycidyl methacrylate, N,N-dimethylaminoethyl acrylate; carboxylic group-containing unsaturated monomers such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, and their anhydrides; sulfonic acid group or sulfuric acid ester group-containing unsaturated monomers such as sulfoethyl (meth)acrylate, 2-acrylamido-2-methylpropanesulfonic acid, sodium methacryloyloxysulfonate; amide monomers such as acrylamide, methacrylamide, N,N-dimethylacrylamide; silicone-modified monomers; polyoxyalkylene macromonomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate; polyvinyl compounds such as divinylbenzene, 1,6-hexanediol diacrylate, etc.

[0024] In the present invention, from the viewpoints of low contamination and elastic suitability of the resulting coating film, etc., it is preferable that the acid value of the shell polymer falls within the range of 4 to 80 mgKOH / g, preferably 5 to 60 mgKOH / g. Outside this range, the elastic suitability is inferior, which is not desirable.

[0025] Further, as at least a part of the polymerizable unsaturated monomer constituting the core-shell emulsion, particularly the polymerizable unsaturated monomer constituting the shell polymer, it is advantageous in terms of the elastic suitability and low contamination of the resulting coating film to use at least one crosslinkable polymerizable unsaturated monomer selected from the above diacetone acrylamide, diacetone methacrylamide, carboxylic acid group-containing unsaturated monomer, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methacrylate.

[0026] From the viewpoints of low contamination and elastic suitability of the resulting coating film, etc., the amount of the crosslinkable polymerizable unsaturated monomer used is preferably in the range of 0.1 to 20 parts by mass, particularly 0.2 to 10 parts by mass, based on 100 parts by mass of the polymerizable unsaturated monomer constituting the core-shell emulsion.

[0027] The above emulsion polymerization is usually carried out in the presence of water and an emulsifier. As the emulsifier, a known anionic surfactant, nonionic surfactant, cationic surfactant, reactive emulsifier, and mixtures thereof can be used without particular limitation as long as they do not contain volatile organic compounds.

[0028] Examples of anionic surfactants include various fatty acid salts, higher alcohol sulfates, alkylbenzene sulfonates, polyoxyethylene alkyl phenyl ether sulfates, polycarboxylic acid type polymer surfactants, and the like. Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, sorbitan fatty acid esters, polyoxyethylene-polyoxypropylene block copolymers, and the like. Examples of cationic surfactants include alkylamine salts, quaternary ammonium salts, and the like. A reactive emulsifier is a surfactant having a polymerizable group in the molecule, and specific examples include "ADEKA LIA SOAP SE-10N" (manufactured by Asahi Denka Co., Ltd., trade name), "AQUALON HS-10" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name), and the like.

[0029] The amount of these emulsifiers used is suitably in the range of 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the total amount of monomers used.

[0030] In the above emulsion polymerization, from the viewpoint of enhancing the stability of the particles, an emulsifier may be added subsequently as needed. As the emulsifier to be added subsequently, sorbitan-based nonionic surfactants are preferred.

[0031] In order to polymerize the polymerizable unsaturated monomer in the above emulsion polymerization, a polymerization initiator is usually added. As the polymerization initiator, any conventionally known one can be used without particular limitation as long as it does not generate volatile organic compounds and is not itself a volatile organic compound. Specific examples include water-soluble inorganic peroxides such as hydrogen peroxide; persulfates such as potassium persulfate and ammonium persulfate. These can be used alone or in combination of two or more. The amount used is desirably 0.1 to 2% by weight based on the amount of the polymerizable unsaturated monomer used. In addition, a peroxide-based polymerization initiator may be used in combination with a metal ion or a reducing agent as a polymerization initiator to carry out redox polymerization.

[0032] In the above emulsion polymerization, if necessary, a chain transfer agent such as mercaptans; a buffer such as sodium bicarbonate may be used. However, it is desirable not to use those that generate volatile organic compounds or those that themselves fall under volatile organic compounds.

[0033] In the aqueous coating composition of the present invention, the solid content of the core / shell emulsion (A) is preferably in the range of 30 to 99.5 parts by mass, more preferably 40 to 90 parts by mass, and still more preferably 50 to 80 parts by mass, based on 100 parts by mass of the solid content of the aqueous coating composition, from the viewpoints of low stainability and elastic suitability of the resulting coating film.

[0034] Crosslinking Agent (B) The crosslinking agent (B) in the aqueous coating composition of the present invention is at least one selected from hydrazide compounds, glycidyl group-containing compounds, carbodiimide compounds, oxazoline compounds, and isocyanate compounds. Among them, from the viewpoints of low stainability and elastic suitability of the resulting coating film, as the crosslinking agent (B), hydrazide compounds, oxazoline compounds, and isocyanate compounds are more preferable. Also, since one-component paints are easier to handle than two-component paints, from the viewpoint of making the aqueous coating composition of the present invention a one-component type, as the crosslinking agent (B), hydrazide compounds, carbodiimide compounds, and oxazoline compounds are more preferable.

[0035] Specific examples of the hydrazide compound include, for example, dihydrazides of saturated aliphatic carboxylic acids having 2 to 18 carbon atoms such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, and sebacic acid dihydrazide; dihydrazides of monoolefinically unsaturated dicarboxylic acids such as maleic acid dihydrazide, fumaric acid dihydrazide, and itaconic acid dihydrazide; dihydrazides of phthalic acid, terephthalic acid, or isophthalic acid; dihydrazide, trihydrazide, or tetrahydrazide of pyromellitic acid; nitrilotriacetic acid trihydrazide, citric acid trihydrazide, 1,2,4-benzenetrihydrazide; ethylenediaminetetraacetic acid tetrahydrazide, 1,4,5,8-naphthalene tetracarboxylic acid tetrahydrazide; polyhydrazides obtained by reacting a low polymer having a carboxylic acid lower alkyl ester group with hydrazine or hydrazine hydrate (hydrazine hydrate), and the like. These can be used alone or in combination of two or more. Among them, from the viewpoints of low contamination and elastic suitability of the obtained coating film, adipic acid dihydrazide, succinic acid dihydrazide, and sebacic acid dihydrazide are preferable as the hydrazide compound.

[0036] Specific examples of the glycidyl group-containing compound include, for example, glycidyl ether compounds such as diglycidyl ether, 2-glycidylphenyl glycidyl ether, and 2,6-diglycidylphenyl glycidyl ether; epoxy resins having a glycidyl ether group or a glycidyl ester group such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, cresol novolak type epoxy resin, and phenol novolak type epoxy resin; glycidyl group-containing polymerizable unsaturated monomers such as glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, and allyl glycidyl ether, and (co)polymers thereof with other polymerizable unsaturated monomers as required. These can be used alone or in combination of two or more.

[0037] A carbodiimide compound is a compound obtained, for example, by causing isocyanate groups of a polyisocyanate compound to undergo a decarboxylation reaction with each other. The carbodiimide compound is preferably water-soluble or water-dispersible, and is not particularly limited, but is preferably a compound having a carbodiimide equivalent in the range of 100 to 800, more preferably 200 to 600. Examples of corresponding commercially available products include "Carbodilite V-02", "Carbodilite V-02-L2", "Carbodilite V-04", "Carbodilite E-01", "Carbodilite E-02" (all are product names manufactured by Nisshinbo Co., Ltd.). These can be used alone or in combination of two or more.

[0038] Specific examples of the oxazoline compound include, for example, low molecular weight poly(1,3-oxazoline) compounds such as 2,2'-p-phenylene-bis-(1,3-oxazoline), 2,2'-tetramethylene-bis-(1,3-oxazoline), 2,2'-octamethylene-bis-(2-oxazoline); furthermore, homopolymers of 1,3-oxazoline group-containing vinyl monomers such as 2-isopropenyl-1,3-oxazoline or vinyl polymers containing 1,3-oxazoline groups obtained by copolymerizing these with various vinyl monomers copolymerizable therewith can be mentioned. It is preferably a water-soluble or water-dispersible compound, and is not particularly limited, but is preferably a compound having an oxazoline group equivalent in the range of 100 to 800, more preferably 200 to 600. Commercially available products of such polyoxazoline compounds include "Epocros K-1000", "Epocros K-1020E", "Epocros K-1030E", "Epocros K-2010E", "Epocros K-2020E", "Epocros K-2030E", "Epocros WS-500", "Epocros WS-700" manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd. These can be used alone or in combination of two or more.

[0039] Specific examples of the isocyanate compound include, for example, aliphatic polyisocyanate, alicyclic polyisocyanate, araliphatic polyisocyanate, aromatic polyisocyanate, and derivatives of these polyisocyanates. These can be used alone or in combination of two or more.

[0040] In the aqueous coating composition of the present invention, the solid content of the crosslinking agent (B) is preferably in the range of 0.1 to 1.0 parts by mass, more preferably 0.2 to 0.9 parts by mass, and even more preferably 0.3 to 0.8 parts by mass, based on 100 parts by mass of the solid content of the aqueous coating composition, from the viewpoints of low stainability and elastic suitability of the obtained coating film.

[0041] Titanium Oxide Pigment (C) From the viewpoint of substrate hiding property, the aqueous coating composition of the present invention may further contain titanium oxide pigment (C) in addition to the above components (A) and (B).

[0042] The titanium oxide pigment (C) is a white pigment and can impart white color to the formed coating film. The titanium oxide pigment (C) may have any crystal form of rutile type or anatase type, but the rutile type is preferred from the viewpoint of excellent weather resistance and substrate color hiding property of the formed coating film. Further, the surface of the titanium oxide pigment (C) may be coated with inorganic oxides such as aluminum oxide, zirconium oxide, silicon dioxide; organic compounds such as amines and alcohols.

[0043] When the aqueous coating composition of the present invention contains the titanium oxide pigment (C), the content of the titanium oxide pigment (C) is preferably in the range of 20 to 200 parts by mass, more preferably 40 to 160 parts by mass, and even more preferably 50 to 120 parts by mass, based on 100 parts by mass of the solid content of the resin contained in the aqueous coating composition, from the viewpoint of excellent low stainability and elastic suitability of the obtained coating film. In this specification, unless otherwise specified, the above core / shell emulsion (A) and crosslinking agent (B) are assumed to be included in the above resin.

[0044] Organic Solvent with Boiling Point of 200 °C or Higher (D) From the viewpoint of elastic suitability, the aqueous coating composition of the present invention may further contain an organic solvent (D) having a boiling point of 200°C or higher, preferably in the range of 210 to 300°C, more preferably in the range of 220 to 290°C, in addition to the components (A) and (B).

[0045] Specific examples of the organic solvent having a boiling point of 200°C or higher include, for example, glycol ethers such as ethylene glycol mono i-propyl ether, ethylene glycol dibutyl ether, diethylene glycol mono n-butyl ether, diethylene glycol mono i-butyl ether, diethylene glycol mono n-propyl ether, diethylene glycol mono i-propyl ether, dipropylene glycol mono n-butyl ether, dipropylene glycol mono i-butyl ether, dipropylene glycol mono n-propyl ether, dipropylene glycol mono i-propyl ether, diethylene glycol dibutyl ether, dipropylene glycol monobutyl ether, and tripropylene glycol monobutyl ether; ester compounds such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethylpentane diol-1,3-diisobutyrate, 2,2,4-trimethyl-1,3-pentanediol mono 2-ethylhexanoate, and 2,2,4-trimethyl-1,3-pentanediol di 2-ethylhexanoate. These can be used alone or in combination of two or more.

[0046] Among them, from the viewpoints of low contamination property and elastic suitability of the obtained coating film, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and / or 2,2,4-trimethyl-1,3-pentanediol diisobutyrate are preferable.

[0047] When the aqueous coating composition of the present invention contains an organic solvent (D) having a boiling point of 200°C or higher, the content of the organic solvent (D) is preferably in the range of 3 to 15 parts by mass, more preferably 4 to 14 parts by mass, still more preferably 5 to 13 parts by mass, based on 100 parts by mass of the solid content of the aqueous coating composition.

[0048] Other Components The aqueous coating composition of the present invention can contain resins other than the above components (A) and (B) as necessary. Examples of such resins include emulsions other than component (A), water-soluble acrylic resins, polyester resins, epoxy resins, urethane resins, etc. These can be used alone or in combination of two or more.

[0049] Specific examples of the emulsion other than the above component (A) include acrylic emulsion, urethane emulsion, silicone emulsion, fluorine emulsion, silicone-modified acrylic emulsion, silicone-modified acrylic emulsion, urethane-modified acrylic emulsion, fluorine-modified acrylic emulsion, etc. These can be used alone or in combination of two or more.

[0050] When the aqueous coating composition of the present invention contains a resin other than the above components (A) and (B), its content is, as a solid content, in the range of 1.0 to 15.0 parts by mass, preferably 2.0 to 12.0 parts by mass, more preferably 3.0 to 9.0 parts by mass based on 100 parts by mass of the resin solid content. This is suitable from the viewpoints of low contamination and elastic suitability of the obtained coating film.

[0051] In addition, the aqueous coating composition of the present invention may further contain, as necessary, pigments other than the titanium oxide pigment (C), organic solvents other than the organic solvent (D) having a boiling point of 200°C or higher, pigment dispersants, surface modifiers, leveling agents, defoamers, surfactants, anti-settling agents, thickeners, fungicides, algaecides, preservatives, plasticizers, fillers, dispersants, ultraviolet absorbers, light stabilizers, etc. as appropriate.

[0052] Examples of the pigments other than the titanium oxide pigment (C) include coloring pigments, extender pigments, metal powders, etc. These can be used alone or in combination of two or more.

[0053] Examples of the coloring pigments include inorganic coloring pigments such as zinc white, iron oxide, and lead yellow, and organic coloring pigments such as phthalocyanine blue and benzidine yellow. Examples of the extender pigments include quartz powder, talc, aluminum oxide, calcium carbonate, precipitated barium sulfate, mica, and the like. Examples of the metal powders include stainless steel powder, zinc powder, aluminum powder, bronze powder, mica powder, and the like.

[0054] Particularly, extender pigments may be used as the pigments from the viewpoints of low pollution and good weather resistance.

[0055] When the aqueous coating composition of the present invention contains the above extender pigment, the content thereof is preferably in the range of 1 to 100 parts by mass, more preferably 5 to 90 parts by mass, and even more preferably 10 to 80 parts by mass, based on 100 parts by mass of the resin solid content, from the viewpoints of low pollution, weather resistance, and the like.

[0056] Waterborne Paint Composition The aqueous coating composition of the present invention may be a one-component composition or a two-component composition. In the case of a two-component composition, generally, a main agent containing component (A) and a curing agent containing component (B) are mixed immediately before coating and then used. When the aqueous coating composition of the present invention is a two-component composition, it may contain a curing catalyst to promote the reaction between the core / shell emulsion (A) and the crosslinking agent (B).

[0057] Coating Method The object to be coated with the aqueous coating composition of the present invention is not particularly limited, and examples include a metal material surface (e.g., iron plate surface, zinc-plated surface, stainless steel surface, aluminum surface, etc.) subjected to a base treatment as desired, a substrate having alkalinity (e.g., concrete, stone, mortar, slate, slate tile), etc., a ceramic substrate, plastic, wood, etc., and an old coating film surface on these substrate surfaces.

[0058] In addition, a sealer and / or a substrate conditioner may be applied to such an object to be coated. In particular, since the aqueous coating composition of the present invention is excellent in elastic fitness, the effects of the present invention can be more effectively exhibited when it is applied on the substrate conditioner.

[0059] The use of the coated object is not particularly limited, but it is suitable for the outer walls of buildings and structures. It is applicable.

[0060] The aqueous coating composition of the present invention can be applied by known means such as spray coating, roller coating, brush coating, flow coating, etc.

[0061] The solid content during coating of the aqueous coating composition of the present invention can be set to 10 to 60%, preferably 15 to 55%.

[0062] The coating amount of the aqueous coating composition of the present invention can be appropriately adjusted according to the use, and is not particularly limited, but generally, it is in the range of 30 to 400 g / m 2 and 50 to 250 g / m 2 is appropriate.

[0063] The aqueous coating composition of the present invention can be easily crosslinked even under normal temperature drying conditions, but forced drying or heat drying may be performed if necessary.

[0064] Cured Coating Film Formed by Curing the Waterborne Paint Composition The cured coating film formed by curing the aqueous coating composition of the present invention is excellent in both stain resistance and elastic fitness, and has the following properties. The aqueous coating composition of the present invention was applied on a glass plate with a thickness of 3.0 mm to form a cured coating film with a film thickness of 70 μm, and the martens hardness measured by an ultra-micro hardness tester at a temperature of 23°C and a load of 5 mN / 25 s on the surface of the coating film when cured for 1 week in an atmosphere of 23°C and 50% humidity is 2.0 to 40.0 N / mm 2 preferably 2.5 to 30.0 N / mm 2 more preferably 3.0 to 20.0 N / mm 2 and a coating film with such properties can be formed.

[0065] In addition, the tensile elastic modulus of the cured coating film obtained by curing the aqueous coating composition of the present invention is 50 to 600 N / mm 2 , preferably 70 to 500 N / mm 2 , more preferably 90 to 400 N / mm 2 , which is preferable. The tensile elastic modulus was measured by applying an emulsion sample onto a degreased iron plate using a 250 μm applicator, drying at 20°C for 7 days, and then peeling off the coating film using mercury. The peeled coating film was measured by EZ Test manufactured by Shimadzu Corporation.

Examples

[0066] Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, the present invention is not limited only to these Examples. Note that both "parts" and "%" are based on mass.

[0067] Preparation of Core / Shell Emulsion Production Example 1 A condenser, a thermometer, and a dropping funnel were attached to a 2-liter four-necked flask. 350 parts of deionized water and 10 parts of Newcol 707SF (Note 1) were charged. After replacing the internal air with nitrogen, the internal temperature was raised to 80°C while stirring. Next, 3% of a pre-emulsion obtained by emulsifying the components having the following composition and 80 parts of a 2.5% aqueous ammonium persulfate solution were added into the reaction vessel and held at 80°C for 20 minutes. Deionized water 550 parts Styrene 170 parts Methyl methacrylate 660 parts n-Butyl acrylate 270 parts 2-Hydroxyethyl acrylate 270 parts 2-Hydroxyethyl methacrylate 20 parts Acrylic acid 10 parts Newcol 707SF (Note 1) 50 parts Thereafter, the remaining pre-emulsion was continuously added dropwise into the reaction vessel over 4 hours. After completion of the dropwise addition, it was stirred at 80 °C for 1 hour, and then 50 parts of deionized water was added all at once. Next, in a separate container, the components of the following composition and 80 parts of a 2.5% aqueous ammonium persulfate solution were stirred and emulsified, and it was continuously added dropwise into the reactor over 1 hour. 500 parts of deionized water 150 parts of styrene 320 parts of methyl methacrylate 30 parts of n-butyl acrylate 30 parts of 2-hydroxyethyl acrylate 20 parts of 2-hydroxyethyl methacrylate 10 parts of acrylic acid 40 parts of diacetone acrylamide 80 parts of Newcol 707SF (Note 1) After completion of the dropwise addition, aging was carried out for 2 hours after completion of the dropwise addition. Thereafter, it was cooled to 30 °C, and adjusted to a solid content of 47% and a pH of 8.5 using aqueous ammonia and deionized water to obtain a core / shell emulsion (A-1) composed of two-layer structured particles with an internally crosslinked layer. The obtained core / shell emulsion (A-1) had an average particle diameter of 160 nm. (Note 1) Newcol 707SF: Trade name, manufactured by Nippon Emulsifier Co., Ltd., an anionic surfactant having a polyoxyethylene chain, non-volatile content 30% Production Examples 2 to 9 In Production Example 1, core / shell emulsions (A-2) to (A-9) were obtained by the same operations as in Production Example 1 except that the blending composition in Table 1 was used.

[0068]

Table 1

[0069] Production Example 10 A condenser, a thermometer, and a dropping funnel were attached to a 2-liter four-necked flask. 350 parts of deionized water and 10 parts of Adeka Ryso Soap SR-1025 (Note 2) were charged. After replacing the internal air with nitrogen, the internal temperature was raised to 80 °C while stirring. Next, 3% of a pre-emulsion obtained by emulsifying the components of the following composition and 80 parts of an 80 parts of 2.5% aqueous ammonium persulfate solution were added into the reaction vessel and maintained at 80 °C for 20 minutes. 350 parts of deionized water 450 parts of methyl methacrylate 40 parts of n-butyl methacrylate 230 parts of 2-hydroxyethyl acrylate 40 parts of 2-hydroxyethyl methacrylate 10 parts of acrylic acid 10 parts of diacetoneacrylamide 20 parts of vinyltriethoxysilane 80 parts of Adeka Ryso Soap SR-1025 (Note 2) Thereafter, the remaining pre-emulsion was continuously added dropwise into the reaction vessel over 2 hours. After completion of the dropping, the mixture was stirred at 80 °C for 1 hour, and then 60 parts of deionized water were added all at once. Next, in a separate container, the components of the following composition and 80 parts of a 2.5% aqueous ammonium persulfate solution were stirred and emulsified, and this was continuously added dropwise into the reactor over 1 hour. 300 parts of deionized water 200 parts of methyl methacrylate 40 parts of n-butyl methacrylate 50 parts of 2-hydroxyethyl acrylate 10 parts of 2-hydroxyethyl methacrylate 10 parts of acrylic acid 10 parts of diacetoneacrylamide 20 parts of vinyltriethoxysilane 50 parts of Adeka Ryso Soap SR-1025 (Note 2) After the dropping was completed, aging was carried out for 2 hours after the dropping was completed. Then, it was cooled to 30 °C, and ammonia water and deionized water were used to adjust the solid content to 48% and the pH to 8.8, and a core / shell emulsion (CS-1) composed of two-layer structure particles having an alkoxysilyl group was obtained. The obtained core / shell emulsion (CS-1) had an average particle diameter of 150 nm. Further, the glass transition temperature of the core was 0 °C, and the glass transition temperature of the shell was 55 °C. (Note 2) Adeka Resop SR-1025: Trade name, manufactured by ADEKA, non-nonylphenol-based reactive emulsifier, non-volatile content 25% Adjustment of Waterborne Paint Composition Example 1 Into a stirring and mixing container, 55 parts (solid content) of core / shell emulsion (A-1), 0.5 part (solid content) of adipic acid hydrazide, 40 parts (solid content) of "Ti-Pure R-706" (trade name, manufactured by Chemours, titanium oxide pigment), 3 parts (solid content) of core / shell emulsion (CS-1), 7 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 5.5 parts of 2,2,4-trimethylpentanediol-1,3-diisobutyrate and 0.5 part of monoethylene glycol were added and stirred and mixed to obtain an aqueous paint composition (1).

[0070] Examples 2 to 14, Comparative Examples 1 to 5 In Example 1, each paint composition was obtained by the same operation as in Example 1 except that the compounding composition in Table 2 was used.

[0071] The numerical values in Table 2 describe the amount of liquid for the solvent and the solid content for the others.

[0072] In addition, each component in Table 2 is as follows. "Carbodilite E-05" Trade name, manufactured by Nisshinbo Chemical Co., Ltd., polyvalent carbodiimide, NCN equivalent: 310, "Takenate WD-730" Trade name, manufactured by Mitsui Chemicals, water-dispersible polyisocyanate

[0073]

Table 2

[0074]

Table 3

[0075] Adjustment of Object to be Coated Coated object 1 On a "slate board" (trade name, manufactured by Partec Co., Ltd., slate test panel), "Eco Cation Sealer" (trade name, manufactured by Kansai Paint Co., Ltd., architectural acrylic silicone resin-based sealer paint) was applied using a brush so that the coating amount was 100 g / m 2 and the coating film was formed by drying at room temperature for 24 hours. Next, "Ares Elastic Holder Waterproof Type" (trade name, manufactured by Kansai Paint Co., Ltd., synthetic resin emulsion-based multi-layer finishing paint) was applied using a porous roller so that the coating amount was 1,000 g / m 2 and the shape was painted in a wavy pattern, and then dried at room temperature for 24 hours to obtain Coated object 1.

[0076] Coated object 2 On a "slate board" (trade name, manufactured by Partec Co., Ltd., slate test panel), "Eco Cation Sealer" (trade name, manufactured by Kansai Paint Co., Ltd., architectural acrylic silicone resin-based sealer paint) was applied using a brush so that the coating amount was 100 g / m 2 and the coating film was formed by drying at room temperature for 24 hours. Next, "Ares Rubber Tile New Rough" (trade name, manufactured by Kansai Paint Co., Ltd., synthetic resin emulsion-based multi-layer paint) was applied using a lysing gun so that the coating amount was 800 g / m 2 and the shape was painted in an uneven pattern, and after drying at room temperature for 24 hours, the same paint was applied using a tile gun so that the coating amount was 1,000 g / m 2 and dried at room temperature for 24 hours to obtain Coated object 2.

[0077] Coated object 3 On the "A1050P" (trade name, manufactured by Partec Co., aluminum panel), apply "Super Virus II" (trade name, manufactured by Kansai Paint Co., terpene-soluble modified epoxy resin-based primer for construction) using a brush so that the coating amount is 140 g / m 2 and form a coating film by drying at room temperature for 24 hours to obtain the object to be coated 3.

[0078] Coating Film Evaluation For each test panel obtained as described above, evaluate the performance of the coating film and show the results in Table 1.

[0079] Tensile modulus of elasticity Apply each aqueous coating composition obtained in the above example onto a polypropylene plate using a 250 μm applicator, and after drying for 7 days in an atmosphere of 23°C and 50% humidity, peel off the coating film. The peeled coating film was measured by EZ Test manufactured by Shimadzu Corporation.

[0080] Martens hardness Apply each aqueous coating composition obtained in the above example onto a glass plate using a 250 μm applicator, and dry for 7 days in an atmosphere of 23°C and 50% humidity to obtain a test panel. It was measured using PICODENTOR HM500 (trade name; manufactured by Fisher Instruments). At that time, the load was set to 5 mN / 25 s, a diamond cone was used as the needle, and the measurement was made at a face angle of 136°.

[0081] Elastic suitability Apply and evaluate under the conditions of the JIS-A6909 temperature and humidity cycling test for architectural topcoats. Coat each aqueous coating composition on the objects to be coated 1 and 2, and dry for 7 days in an atmosphere of 23°C and 50% humidity. Immerse each test specimen in tap water at 23 ± 2°C for 18 hours, then immediately cool it in a thermostat at -20 ± 2°C for 3 hours, and then immediately heat it in another thermostat at 50 ± 3°C for 3 hours. Repeat the operation with this 24-hour cycle 10 times, then leave it standing in the laboratory for 2 hours, and visually and using a magnifying glass evaluate the presence or absence of cracks, peeling, and swelling of the coating film. ◎: No cracks, peeling, or swelling are visible either visually or with a magnifying glass. ○: No cracks, peeling, or swelling can be seen visually, but any of cracks, peeling, or swelling can be seen with a magnifying glass. ×: Any of cracks, peeling, or swelling can be seen visually.

[0082] Stain resistance Each aqueous paint composition was applied to the object to be painted 3 so that the film thickness or coating amount was 100 g / m 2 and painted so that the painted surface was smooth. After drying for 24 hours in an atmosphere of 23°C and 50% humidity, a test piece was prepared. In Ota Ward, Tokyo, the test surface was fixed so as to face south and be at an angle of 30 degrees with respect to the horizontal plane, and the contamination state after exposure for 6 months was visually evaluated according to the following criteria. Also, the color difference ΔE before and after exposure was evaluated with a color difference meter "CR-400" (trade name, manufactured by Minolta Co., Ltd.). ◎: ΔL is less than 5 (the stain is hardly noticeable). ○: ΔL is 5 to 10 (the stain is slightly noticeable but at a practical level). ×: ΔL exceeds 10 (the stain is noticeable).

[0083] As described above, the embodiments and examples of the present invention have been specifically described. However, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible.

Claims

1. The core is a polymer having a glass transition temperature of 5 to 50°C, the shell is a polymer having a glass transition temperature of 50 to 90°C, a core / shell emulsion (A) in which ΔTg (glass transition temperature of the shell - glass transition temperature of the core) is 40 to 60°C, at least one crosslinking agent (B) selected from hydrazide compounds, glycidyl group-containing compounds, carbodiimide compounds, oxazoline compounds, and isocyanate compounds, and an organic solvent (D) having a boiling point of 200°C or higher is contained in an amount of 3 to 15 parts by mass based on 100 parts by mass of the solid content in the aqueous paint composition The polymerizable unsaturated monomer constituting the core contains 2-hydroxyethyl (meth)acrylate and (meth)acrylic acid, The polymerizable unsaturated monomer constituting the shell contains 2-hydroxyethyl (meth)acrylate, (meth)acrylic acid, and diacetone (meth)acrylamide, The organic solvent (D) having a boiling point of 200°C or higher contains 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate. Aqueous paint composition, characterized in that However The aqueous paint composition is a copolymer obtained by copolymerizing a monomer mixture containing a carbonyl group-containing polymerizable unsaturated monomer (a), a carboxyl group-containing polymerizable unsaturated monomer (b), and a hydrophilic polymerizable unsaturated monomer (c) other than monomer (a) and monomer (b) in the presence of a hydrophilic organic solvent. The total copolymerization ratio of the carboxyl group-containing polymerizable unsaturated monomer (b) and the hydrophilic polymerizable unsaturated monomer (c) is 30% by mass or more in all the polymerizable unsaturated monomers used for the production of the copolymer (I), and the copolymerization ratio of the carboxyl group-containing polymerizable unsaturated monomer (b) is within the range of 0.1 to 70% by mass. It does not contain a carbonyl group-containing copolymer (I)

2. The core / shell emulsion (A) is such that The aqueous paint composition according to claim 1, wherein the mass ratio of the core polymer to the shell polymer is in the range of 50 / 50 to 90 / 10 in the ratio of the former / latter.

3. The aqueous paint composition according to claim 1 or 2, wherein the solid content of the core / shell emulsion (A) is 30 to 99.5 parts by mass based on 100 parts by mass of the solid content of the aqueous paint composition.

4. The aqueous coating composition according to any one of claims 1 to 3, further containing 20 to 200 parts by mass of titanium oxide pigment (C) based on 100 parts by mass of the solid content of the resin contained in the aqueous coating composition.

5. The aqueous coating composition according to any one of claims 1 to 4, further containing a core / shell acrylic emulsion having an alkoxysilyl group other than component (A).

6. A cured coating film with a thickness of 70 μm is formed on a glass plate with a thickness of 3.0 mm, and the Martens hardness measured at a temperature of 23°C and a load of 5 mN / 25 s by an ultra-micro hardness tester on the coating film surface when cured for 1 week in an atmosphere of 23°C and 50% humidity is 2.0 to 40.0 N / mm ２ The aqueous coating composition according to any one of claims 1 to 5, which can form a coating film having such properties.

7. A coating film forming method comprising a step of coating an object to be coated with the aqueous coating composition according to any one of claims 1 to 6.

8. A coated article having a cured coating film formed by the aqueous coating composition according to any one of claims 1 to 6.

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