JP6349180B2 - Room temperature curable aqueous coating composition - Google Patents

Description

  The present invention relates to a room temperature curable aqueous coating composition, and more particularly to a room temperature curable aqueous coating composition with improved secondary adhesion.

  In the past, solvent-based paints have been mainly used for painting buildings and outdoor buildings. Since solvent-based paints have problems such as hygiene and pollution due to solvent volatilization during film formation, the shift from solvent-based paints to water-based paints has been conspicuous in recent years. In outdoor applications, when a coating film deteriorates, a paint is often directly coated thereon, and adhesion to various surfaces is an important performance.

  Japanese Patent Application Laid-Open No. 4-249487 (Patent Document 1) discloses an aqueous normally dry cross-linking type resin composition for curing an acrylic polymer emulsion using diacetone acrylamide or diacetone methacrylamide with a dihydrazide curing agent. ing. This kind of room-temperature curable paint must be improved in storage stability so that it does not progress during storage because it crosslinks at room temperature. However, if storage stability is too good, the crosslinkability is insufficient and the film performance is poor. Is lacking. The composition of Patent Document 1 provides an excellent coating film with good storage stability. However, although the paint of Patent Document 1 mentions water-resistant swelling on the base coating film, this is an appearance evaluation after 24 hours of immersion. With regard to the adhesion of the paint, it was found that when a more severe water resistance adhesion test was performed, coating film swelling occurred and the adhesion of the coating film (that is, secondary adhesion) was not sufficient. Thus, when the coating film is exposed to a harsh environment, it is difficult to achieve both storage stability and water resistance only by controlling the crosslinkability of the coating film.

Japanese Patent Laid-Open No. 4-249487

  The present invention provides a room temperature curable aqueous coating composition having improved adhesion to a base coating film, particularly secondary adhesion.

As a result of intensive studies to solve the above-mentioned problems, the present inventor has adjusted the water permeability of the coating film to an appropriate range, so that the coating film does not swell even when a severe water resistance test is performed. As a result, the present invention has been completed.
That is, the present invention
(A) diacetone (meth) acrylamide, and (b) an unsaturated monomer copolymerizable with the component (a),
An aqueous emulsion (A) obtained by emulsion polymerization of a monomer mixture in which the amount of component (a) is 4 to 40% by mass with respect to the total monomer mass in the presence of a chain transfer agent,
Hydrazine and / or hydrazide derivative (B), and aqueous urethane polymer (C),
A room temperature curable water-based coating composition comprising:
The content of the hydrazine and / or hydrazide derivative (B) is such that the hydrazine and / or hydrazide derivative (B) is used with respect to 1 equivalent of diacetone (meth) acrylamide (a) used for the polymerization of the aqueous emulsion (A). Is an amount such that the equivalent of the hydrazino group possessed by
A room temperature curable aqueous coating composition,
I will provide a.

で表されるジヒドラジド化合物である。 The hydrazide derivative preferably has the chemical formula:

It is a dihydrazide compound represented by these.

  In the present invention, the amount of the chain transfer agent is 100 / 0.1 to 100 / 3.0 in a ratio of the mass of the monomer mixture (total of component (a) and component (b)) / chain transfer agent. Within the range is preferred.

  Moreover, in this invention, the compounding quantity of the said water-based urethane polymer (C) is ratio of 1 / 100-50 / 100 by the ratio of the non-volatile matter mass of the water-based urethane polymer (C) / non-volatile matter mass of the water-based emulsion (A). It is preferable to be within the range.

  In the present invention, the chain transfer agent is lauryl mercaptan, n-butyl mercaptan, t-butyl mercaptan, dodecyl mercaptan, octyl mercaptan, thioglycolic acid-2-ethylhexyl, 2-methyl-5-t-butyl. It is preferably one or more selected from the group consisting of thiophenol, carbon tetrabromide, and α-methylstyrene dimer.

  The room temperature curable aqueous coating composition obtained by the present invention exhibits very excellent adhesion, particularly secondary adhesion, to the base coating film. In the present invention, by emulsion polymerization of a monomer mixture containing (a) diacetone (meth) acrylamide and (b) an unsaturated monomer copolymerizable with the component (a) in the presence of a chain transfer agent, The water permeability of the obtained coating film was adjusted to an appropriate range, whereby coating film swelling could be prevented, adhesion was greatly improved, and secondary adhesion was improved.

  “Secondary adhesion” in the present invention means adhesion when a water-based paint is applied on a base coating film and then submerged for several days, and then a peel test is performed. The detailed method of secondary adhesion is described in the examples. The base coating film may be a sealer such as rust preventive or a deteriorated old coating film, and may be either a water-based paint or a solvent-type paint.

Ingredient (A)
In this invention, (a) diacetone (meth) acrylamide and (b) the unsaturated monomer which can be copolymerized with the said component (a) are contained, and the quantity of a component (a) is 4 with respect to monomer total mass. An aqueous emulsion (A) obtained by emulsion polymerization of a monomer mixture of ˜40 mass% in the presence of a chain transfer agent is formed.

  In this specification, the notation of diacetone (meth) acrylamide means either diacetone acrylamide or diacetone methacrylamide, or a combination thereof. These are commercially available from Nippon Kasei Corporation.

  The unsaturated monomer (b) copolymerizable with the diacetone (meth) acrylamide (a) is not particularly limited as long as it is a copolymerizable monomer. For example, a hydroxyl group-containing unsaturated monomer, an acid group-containing unsaturated monomer, Examples include acrylic ester monomers and other unsaturated monomers.

  Examples of the hydroxyl group-containing unsaturated monomer include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, Plaxel FM-1 (ε-caprolactone-modified hydroxyethyl methacrylate manufactured by Daicel Chemical Industries), polyethylene glycol Mention may be made of alcohols such as monoacrylate or monomethacrylate, polypropylene glycol monoacrylate or monomethacrylate.

  Examples of the acidic group-containing unsaturated monomer include carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid and maleic acid.

  Examples of the acrylic ester monomers include esters of acrylic acid or methacrylic acid such as methyl, ethyl, propyl, butyl, hexyl, ethylhexyl, cyclohexyl, and lauryl.

  Examples of the other unsaturated monomers include unsaturated hydrocarbons such as styrene, α-methylstyrene, vinylnaphthalene, butadiene, and isoprene; nitriles such as acrylonitrile and methacrylonitrile; acrylamide, methacrylamide, and N-methylolacrylamide. Amides such as N, N-dimethylacrylamide; polyoxyalkylene derivatives such as polyethylene glycol methyl ether acrylate or methacrylate; divinylbenzene, allyl methacrylate, ethylene glycol di (meth) acrylate, glycerin tri (meth) acrylate, hexanediol di 1 carbon-carbon unsaturated bond such as (meth) acrylate, butanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, etc. Having two or more in the child; and the like.

  Arbitrary appropriate emulsifiers and initiators can be used as the emulsifier and initiator used in emulsion polymerization of unsaturated monomers.

  The diacetone (meth) acrylamide (a) is used at 4 to 40% by mass based on the total monomer mass. This amount is preferably 4.5 to 18.0% by weight. In the present invention, by using diacetone (meth) acrylamide (a) in the above mass range, the water permeability of the coating film is secured and the secondary adhesion is improved. When the amount of diacetone (meth) acrylamide (a) is less than 4% by mass, the water permeability of the coating film is lowered even when a chain transfer agent is used, so that the secondary adhesion is lowered. When the amount of diacetone (meth) acrylamide (a) is more than 40% by mass, the water permeability becomes too high, the water absorption amount of the top coating itself is high, and the strength of the coating film itself is impaired, resulting in poor secondary adhesion. . When the coating film is immersed in water, water-soluble components are eluted from the coating film and accumulate at the interface between the deteriorated coating film and the coating film coated thereon. When the concentration of the water-soluble component increases, water is pushed from the surface of the coating film to the interface by osmotic pressure, and when the water pressure at the coating film interface exceeds a certain level, the adhesive force is overcome and the coating film bulge is generated. When the water permeability of the coating film increases, the water pressure at the coating film interface does not increase, and thus no swelling of the coating film occurs. However, when the water permeability is too high, the strength of the coating film is impaired as described above.

  Since the unsaturated monomer (b) copolymerizable with the component (a) is everything except the component (a) in the monomer mixture, both (both component (a) and component (b)) In addition, it may be 100% by mass.

  In the present invention, the monomer mixture (component (a) and component (b) above) is emulsion-polymerized in the presence of a chain transfer agent. Specifically, the chain transfer agent is an alkyl mercaptan such as lauryl mercaptan, n-butyl mercaptan, t-butyl mercaptan, dodecyl mercaptan, octyl mercaptan; thioglycolate-2-ethylhexyl, 2-methyl-5-t -Butylthiophenol, carbon tetrabromide, α-methylstyrene dimer and the like can be mentioned.

  The mass ratio of the monomer mixture (the sum of the components (a) and (b)) and the chain transfer agent is 100 within a range that does not impair the effects of the present invention by the ratio of the mass of the monomer mixture / the mass of the chain transfer agent. Any value other than / 0 can be taken, and it is preferably 100 / 0.1 to 100 / 3.0. When the ratio of the mass of the monomer mixture / the mass of the chain transfer agent is within the above range, the water resistance and secondary adhesion of the coating film are improved.

  An aqueous emulsion (A) is obtained by the emulsion polymerization. Any appropriate volume average particle diameter can be adopted as the volume average particle diameter of the resin particles in the aqueous emulsion as long as the effects of the present invention are not impaired. Preferably it is 0.01-10 micrometers, More preferably, it is 0.05-1 micrometer. The volume average particle diameter of the resin particles can be measured by a laser light scattering method or the like.

  Moreover, it is desirable to adjust the pH of the aqueous emulsion (A) in order to improve stability. The pH after the adjustment is preferably 6 to 10, and more preferably 7 to 9. The pH adjustment of the aqueous emulsion (A) is preferably performed using a basic compound. Examples of basic compounds used for pH adjustment include ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, etalamine, diethanolamine, triethanolamine, dimethylethanolamine, and other amines, and water. Examples thereof include alkali metal hydroxides such as potassium oxide and sodium hydroxide.

Ingredient (B)
The aqueous coating composition of the present invention contains hydrazine and / or a hydrazide derivative (B). In the present specification, the “hydrazino group” means both a hydrazino group and a hydrazide group. The hydrazine and / or hydrazide derivative (B) acts as a curing agent. For example, the acetyl group derived from the component (a) contained in the aqueous emulsion (A) reacts with the hydrazino group of the hydrazine and / or hydrazide derivative (B) to cause crosslinking and cure.

で表されるジヒドラジド化合物であるのが好ましい。式中、ｎは０〜８であり、好ましくは１〜６であり、より好ましくは２〜４であり、さらに好ましくは４である。ｎが９以上の場合、親水性が低下し、水に溶解することが困難となる。 The hydrazide derivative has the following chemical formula:

It is preferable that it is a dihydrazide compound represented by these. In formula, n is 0-8, Preferably it is 1-6, More preferably, it is 2-4, More preferably, it is 4. When n is 9 or more, the hydrophilicity is lowered and it is difficult to dissolve in water.

  As the component (B), a dihydrazide compound represented by the above chemical formula is more preferably used, and a dihydrazide compound represented by the above chemical formula and n is more preferably 2-4.

The amount of hydrazine and / or hydrazide derivative (B) contained in the aqueous coating composition of the present invention is the same as that of diacetone (meth) acrylamide (a) used in the polymerization of the aqueous emulsion (A) contained in the aqueous coating composition. ) The amount of the hydrazino group that the hydrazine and / or hydrazide derivative (B) has is equivalent to 2 equivalents or less with respect to 1 equivalent.
For example, when the component (B) contains hydrazine, the amount of hydrazine used is 2 equivalents or less with respect to 1 equivalent of diacetone (meth) acrylamide (a).
For example, when the component (B) contains the dihydrazide compound, the equivalent of the hydrazino group (hydrazide group) of the dihydrazide compound is 2 equivalents or less with respect to 1 equivalent of diacetone (meth) acrylamide (a). It is used in an amount, that is, an amount such that the dihydrazide compound is 1 equivalent or less.
The content of the hydrazine and / or hydrazide derivative (B) is such that the hydrazino group is 1.2 equivalents or less with respect to 1 equivalent of diacetone (meth) acrylamide (a) used in the polymerization of the aqueous emulsion (A). It is more preferable that the amount of hydrazino group is 0.05 to 1 equivalent. Here, “below” means a concept that does not include 0, and includes a minute amount.
When the content of the hydrazine and / or hydrazide derivative (B) is more than 2.0 equivalents as the equivalent of the hydrazino group, no improvement in performance is observed with the content, and the initial low-temperature water resistance decreases. . When the content of the hydrazine and / or hydrazide derivative (B) is 0.05 to 1 equivalent as the equivalent of the hydrazino group, the low-temperature initial water resistance is extremely good. If the hydrazine and / or hydrazide derivative (B) is not contained, the water-resistant swelling and secondary adhesion of the coating film are lowered.

Ingredient (C)
The water-based coating composition of the present invention contains a water-based urethane polymer (C). This aqueous urethane polymer (C) promotes the film formation of the component (A) by the cohesive force of the urethane group, and improves the strength of the coating film.

  The aqueous urethane polymer (C) in the present invention comprises a polyol compound (C-1), a compound (C-2) having an active hydrogen group and a hydrophilic group in the molecule, an organic polyisocyanate (C-3), and if necessary. It is a polymer prepared using a chain extender and a polymerization terminator, and is obtained by dissolving or dispersing it in water.

  The polyol compound (C-1) is not particularly limited as long as it contains two or more hydroxyl groups. For example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, Polyhydric alcohols such as trimethylolpropane and glycerin, polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol; dicarboxylic acids such as adipic acid, sebacic acid, itaconic acid, maleic anhydride, phthalic acid, and isophthalic acid Polyester polyols obtained from acids and glycols such as ethylene glycol, triethylene glycol, propylene glycol, butylene glycol, tripropylene glycol, neopentyl glycol; polycaprolactone poly Lumpur; polybutadiene polyols; polycarbonate polyols; polythioether polyols; and the like. The said polyol compound may be used independently or may be used together 2 or more types.

  The compound (C-2) having an active hydrogen group and a hydrophilic group in the molecule includes an active hydrogen and an anion group {an anion group or an anion-forming group (which reacts with a base to form an anion group. In this case, Is converted into an anionic group by neutralizing with a base before, during or after the urethanization reaction)} (for example, Japanese Patent Publication No. 42-24192 and Japanese Patent Publication No. 55-41607) Those described in the specification of the gazette, specific examples include α, α-dimethylolpropionic acid, α, α-dimethylolbutyric acid, and the like, and compounds known as compounds having an active hydrogen and a cationic group in the molecule (for example, JP-B-43) And those known as compounds having an active hydrogen and a nonionic hydrophilic group in the molecule (for example, JP-B-4) Those described in -41718 discloses, specifically, polyethylene glycol, alkyl alcohol alkylene oxide adduct) and the like.

The organic polyisocyanate (C-3) is not particularly limited as long as it has two or more isocyanate groups in the molecule. For example, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2 , 2,4-trimethylhexamethylene diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, dicyclohexylmethane-4,4′-diisocyanate, methylcyclohexyl-2,4-diisocyanate, methylcyclohexyl-2,6 -Diisocyanate, xylylene diisocyanate, 1,3-bis (isocyanate) methylcyclohexane, tetramethylxylylene diisocyanate, transcyclohexane-1,4-diisocyanate, lysine diisocyanate Aliphatic diisocyanates such as anate, 2,4-toluylene diisocyanate, 2,6-toluylene diisocyanate, diphenylmethane-4,4′-diisocyanate, 1,5′-naphthene diisocyanate, tolidine diisocyanate, diphenylmethylmethane diisocyanate, tetra Aromatic diisocyanates such as alkyldiphenylmethane diisocyanate, 4,4′-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, lysine ester triisocyanate, triphenylmethane triisocyanate, 1,6,11-undecane triisocyanate, 1,8 -Diisocyanate-4,4-isocyanate methyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, etc. Triisocyanates, and the like. Moreover, it may be used as a dimer or trimer (isocyanurate bond) of these polyisocyanate compounds, or may be used as a biuret by reacting with an amine. Further, polyisocyanates having urethane bonds obtained by reacting these polyisocyanate compounds with polyols can also be used.
It is more preferable to use an aliphatic diisocyanate as the organic polyisocyanate (C-3). By preparing the water-based urethane polymer (C) using an aliphatic diisocyanate, the water permeability of the resulting coating film can be adjusted to an appropriate range, and good low temperature initial water resistance can be obtained. There is.

  The chain extender that may be added as necessary when preparing the aqueous urethane polymer (C) is not particularly limited as long as it contains two or more active hydrogen groups, and examples thereof include low molecular polyols, polyamines, and water. It is done.

  Examples of the low molecular polyol include ethylene glycol, propylene glycol, 1,4-butanediol, 3-methylpentanediol, 2-ethyl-1,3-hexanediol, and trimethylolpropane.

  Examples of the polyamine include ethylenediamine, hexamethylenediamine, diethylenetriamine, hydrazine, xylylenediamine, and isophoronediamine.

  Moreover, as a polymerization terminator, the compound which has one active hydrogen in a molecule | numerator, or a monoisocyanate compound is mentioned.

  Examples of the compound having one active hydrogen in the molecule include monoalcohol (eg, alkyl alcohols such as methanol, butanol and octanol, alkyl alcohol alkylene oxide adducts), or monoamines (eg, butylamine, dibutylamine, etc.) Of the alkylamine).

  Examples of the monoisocyanate compound include methyl isocyanate, ethyl isocyanate, propyl isocyanate, butyl isocyanate, lauryl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, and tolylene isocyanate.

  The reaction method for producing the water-based urethane polymer (C) is a one-shot method in which each component is reacted at once or a multistage method in which each component is reacted stepwise {part of an active hydrogen-containing compound (for example, a polymer polyol) and Any method of producing an NCO-terminated prepolymer by reacting isocyanate and then reacting the remainder of the active hydrogen-containing compound may be used. The synthesis reaction of the aqueous urethane polymer (C) is usually performed at 40 to 140 ° C, preferably 60 to 120 ° C. In order to accelerate the reaction, a tin-based catalyst such as dibutyltin laurate or tin octylate used in a normal urethanization reaction or an amine-based catalyst such as triethylenediamine may be used. The above reaction may be carried out in an organic solvent inert to isocyanate (for example, acetone, toluene, dimethylformamide, etc.), and the solvent may be added during or after the reaction.

  The aqueous urethane polymer (C) in the present invention is a known method (in the case of an anion-forming group, a method of neutralizing with a base to form an anion group, and in the case of a cation-forming group, a quaternizing agent is used to form a cation group. A water-based urethane polymer is obtained by treating with a method of forming or a method of neutralizing with an acid to form a cationic group and then dissolving in water.

  The step of dissolving in water is not particularly limited, and may be after the reaction or in the middle of the multistage method. For example, when dissolving in water at the stage of the NCO-terminated prepolymer, the aqueous urethane polymer (C) is obtained by dissolving in water while chain-extending with water and / or polyamine.

  When an inert organic solvent is used for the isocyanate, the solvent may be removed after dissolving in water.

  The amount of the water-based urethane polymer (C) is a mass ratio of the non-volatile content of the water-based urethane polymer (C) / non-volatile content of the aqueous emulsion (A), and may be any value other than 0/100 as long as the effects of the present invention are not impaired. The value can be taken, and is preferably 1/100 to 50/100. When the mass ratio of the non-volatile content of the water-based urethane polymer (C) to the non-volatile content of the aqueous emulsion (A) is in the above range, the water resistance and secondary adhesion of the coating film are improved.

Other Components The aqueous coating composition in the present invention may contain other components as required in addition to the components (A) to (C). Other components include, for example, pigments, design materials (sand, dredged sand, colored sand, beads, colored chips, mineral chips, glass chips, wooden chips, colored beads, etc.), other aqueous resins, film-forming aids, surface conditioners , Antiseptics, fungicides, antifoaming agents, light stabilizers, ultraviolet absorbers, antioxidants, pH adjusters and the like.

  The pigment is not particularly limited, for example, an azo chelate pigment, an insoluble azo pigment, a condensed azo pigment, a monoazo pigment, a disazo pigment, a diketopyrrolopyrrole pigment, a benzimidazolone pigment, a phthalocyanine pigment, Indigo pigment, thioindigo pigment, perinone pigment, perylene pigment, dioxane pigment, quinacridone pigment, isoindolinone pigment, naphthol pigment, pyrazolone pigment, anthraquinone pigment, anthorapyrimidine pigment, metal complex Organic color pigments such as pigments: yellow lead, yellow iron oxide, chromium oxide, molybdate orange, bengara, titanium yellow, zinc white, carbon black, titanium dioxide, cobalt green, phthalocyanine green, ultramarine, cobalt blue, phthalocyanine blue, Cobalt bio Inorganic colored pigments such as iron; mica pigments (titanium dioxide-coated mica, colored mica, metal-plated mica); graphite pigments, alumina flake pigments, metal titanium flakes, stainless steel flakes, plate-like iron oxide, phthalocyanine flakes, metal-plated glass Flakes, other colored and colored flat pigments; extender pigments such as titanium oxide, calcium carbonate, barium sulfate, barium carbonate, magnesium silicate, clay, talc, silica, calcined kaolin, and the like.

  When the aqueous coating composition contains a pigment, the pigment mass concentration (PWC) with respect to the solid content of the aqueous coating composition is preferably in the range of 5 to 70% by mass. When the PWC is less than 5% by mass, the base concealing property is inferior, and when the PWC exceeds 70% by mass, the weather resistance may be lowered. The pigment mass concentration (PWC) is more preferably 20 to 45% by mass.

  It does not specifically limit as a preparation method of an aqueous coating composition, It can prepare by stirring each component mentioned above with a stirrer etc. When pigments or design materials are included in the aqueous coating composition, those having good dispersibility can be mixed with a stirrer, and as another method, a sand grind is added to a vehicle containing water, a surfactant or a dispersant. What was previously disperse | distributed using the mill etc. can also be added.

  The room temperature curable aqueous coating composition of the present invention is not particularly limited with respect to its coating method and drying conditions, and generally well-known ones can be applied thereto. In addition, the coating composition of the present invention can be used for various applications, and exhibits excellent performance particularly under normal temperature drying to forced drying conditions. Note that forced drying generally means heating at about 80 ° C., but may be heating up to about 150 ° C., for example.

  The coating object to which the aqueous coating composition of the present invention is applied is not particularly limited, and examples thereof include metal substrates such as iron and stainless steel and their surface treated products, cement substrates such as plaster, polyesters, and acrylics. Examples thereof include a plastic base material. In addition, various construction materials such as building materials and structures composed of these base materials, various coating materials for the automobile industry such as automobile bodies and parts, various coating materials in the industrial field such as electrical appliances and electronic parts. Can be mentioned. The aqueous coating composition of the present invention can also be applied at the time of refurbishing each of the above objects.

  Each of the above-mentioned surface refurbishing methods in the present invention can be performed without applying an undercoat before applying the aqueous coating composition. In addition, when stain | pollution | contamination and rust are especially severe, after apply | coating undercoat, the said water-based coating composition can be apply | coated. Examples of the object surface include an inner wall surface of a vehicle unit, an inner wall for general buildings such as a house and an office, an outer wall surface, and a ceiling portion. Moreover, as an iron surface, it is an internal and external iron surface for general buildings, such as an iron door of a condominium or a factory, a handrail, a playground equipment, a utility pole, etc.

  The present invention will be described in more detail based on examples. The present invention should not be construed as being limited to these examples. In the examples, parts and percentages are based on weight unless otherwise indicated.

Preparation of resin emulsion
Production Example 1
In a glass reaction vessel equipped with a dropping funnel, a reflux condenser, a stirrer, and a thermometer, 50.50 parts of deionized water and 1.50 parts of an emulsifier (Belex SS-H; manufactured by Kao Corporation) as a reactive emulsifier, The content temperature was 85 ° C. Among them, methacrylic acid 2.78, styrene 13.90 parts, 2-ethylhexyl acrylate 28.07 parts, butyl methacrylate 28.07 parts, methyl methacrylate 23.17 parts, diacetone acrylamide (hereinafter referred to as “DAAM”) And a pre-emulsion solution comprising 4.01 parts, 1.20 parts dodecyl mercaptan, 4.00 parts emulsifier (Belex SS-H; manufactured by Kao Corporation), and 51.40 parts deionized water, and polymerization. As an initiator, 10 parts of a 5.0% aqueous solution of ammonium persulfate was dropped from a dropping funnel at a constant rate over 2 hours to be reacted. The reaction temperature was maintained at 85 ° C. After the completion of dropping, the temperature was kept at the same temperature for 3 hours and then cooled to 30 ° C. and taken out to obtain a resin emulsion having a nonvolatile content of 49%.

Production Examples 2-14
Although it is the same as that of the said manufacture example 1, the monomer mixing | blending was changed as described in following Table 1, and the resin emulsion was obtained.

滴下終了後３０分より、３０分間０．７部の過硫酸アンモニウムを７部の脱イオン水に溶かした溶液を滴下し、さらに２時間８０℃に保ってエマルションＡを得た。 Production Example 15
An aqueous emulsion A of Production Example 1 described in paragraph [0012] of Patent Document 1 (JP-A-4-49587) was prepared.
242 parts of deionized water and 2.4 parts of Newcol 707SF (Daiichi Kogyo Seiyaku Co., Ltd., solid content: 30%) 2.4 parts were added to a 2 liter four-necked flask, and kept at 80 ° C. after purging with nitrogen. Immediately before the pre-emulsion having the following composition was dropped, 0.7 part of ammonium persulfate was added, and the pre-emulsion was dropped over 3 hours.

From 30 minutes after the completion of the dropping, a solution prepared by dissolving 0.7 parts of ammonium persulfate in 7 parts of deionized water was added dropwise for 30 minutes, and the emulsion was further maintained at 80 ° C. for 2 hours to obtain an emulsion A.

Manufacture of aqueous urethane polymer
Production example A
In a closed reaction vessel equipped with a thermometer and a stirrer, 162.0 parts of polyethylene adipatediol (number average molecular weight 2000), 47.6 parts of dimethylolpropionic acid, 13.8 parts of n-butanol, 176. of isophorone diisocyanate (IPDI). After charging 0 parts and 400.0 parts of acetone and replacing the reaction system with nitrogen gas, the reaction was carried out with stirring at 80 ° C. for 7 hours to obtain an acetone solution of an NCO-terminated urethane prepolymer having an NCO% content of 2.68%. It was. The obtained acetone solution was cooled to 30 ° C., and 35.9 parts of triethylamine was added. Next, 895.0 parts of water was added to the acetone solution, and acetone was removed under reduced pressure at 50 to 60 ° C. to obtain 1300.0 parts of an aqueous urethane polymer having a solid content of 30.0%.

Production example B
In a sealed reaction vessel equipped with a thermometer and a stirrer, 246.7 parts of polypropylene glycol (number average molecular weight 2000, PP-2000, manufactured by Sanyo Chemical Industries), 15.1 parts of 1,4-butanediol, dimethylolpropionic acid 17.9 parts, 123.0 parts of IPDI, and 400 parts of acetone were charged, the reaction system was replaced with nitrogen gas, and the reaction was carried out for 7 hours at 80 ° C. with stirring to react with an NCO-terminated urethane prepolymer having an NCO% content of 1.67%. A polymer was obtained. The obtained acetone solution was cooled to 30 ° C. and 13.5 parts of triethylamine was added. Next, 692.0 parts of water was added to the acetone solution, and acetone was removed at 50 to 60 ° C. under reduced pressure to obtain 1000.0 parts of an aqueous urethane polymer having a solid content of 30.0%.

Production Example C
In a closed reaction vessel equipped with a thermometer and a stirrer, 246.7 parts of polycaprolactone diol (number average molecular weight 2000), 7.4 parts of 1,4-butanediol, 5.1 parts of trimethylolpropane, dimethylolpropionic acid 17.9 parts, 123.0 parts of IPDI, and 400 parts of acetone were charged, the reaction system was replaced with nitrogen gas, and the reaction was carried out for 7 hours at 80 ° C. with stirring to react with an NCO-terminated urethane prepolymer having an NCO% content of 1.67%. A polymer was obtained. The obtained acetone solution was cooled to 30 ° C. and 13.5 parts of triethylamine was added. Next, 685.0 parts of water was added to the acetone solution, and acetone was removed under reduced pressure at 50 to 60 ° C. to obtain 970.0 parts of an aqueous urethane polymer having a solid content of 30.0%.

Production Example D
A closed reaction vessel equipped with a thermometer and a stirrer was charged with 240 parts of polyethylene glycol (PEG) 6000 (molecular weight 6000) and 99 parts of an ethylene oxide (EO) 20 mol adduct of 2-octyl-1-dodecanol under reduced pressure. (10 mmHg or less) at 90 to 100 ° C. for 3 hours to make the water content of the system 0.03%. Next, the mixture was cooled to 80 ° C., 14.8 parts of hexamethylene diisocyanate (HMDI) was added, and the mixture was reacted at 80 to 90 ° C. for 2 hours under a nitrogen stream to confirm that the isocyanate content was 0%. Next, 825 parts of water was added and uniformly mixed and then cooled to obtain 1150.0 parts of an aqueous urethane polymer having a solid content of 30.0%.

Example 1
Titanium consisting of 3 parts DISPER BKY190 (commercially available from Big Chemie) as a pigment dispersant, 20 parts titanium oxide (trade name: TIPAQUE titanium CR-95, produced by Ishihara Sangyo Co., Ltd.) as a pigment for white paint, and 4 parts deionized water To the white dispersion paste, 52 parts of the resin emulsion (nonvolatile content (NV) 49%) obtained in Production Example 1 and 17 parts of the aqueous urethane polymer (nonvolatile content 30%) obtained in Production Example A were increased. 3.1 parts of Toxsolvent (a petroleum-based mixed solvent manufactured by Shoei Chemical Co., Ltd.) as an auxiliary agent, 0.05 parts of Biocut AF-40 (manufactured by Nippon Soda Co., Ltd.) as an antiseptic, and 0. 03 parts, 0.1 part of 25% aqueous ammonia as a pH adjuster, 2 parts of Primal ASE-60 (Rohm and Haas) as a thickener, 3 parts of a phosphate dihydrazide 7.5% aqueous solution to obtain an aqueous coating composition of BYK-024 (manufactured by BYK Chemie) as a defoaming agent were mixed 0.2 parts.

  The evaluation test shown below was done using the obtained water-based coating composition. The composition of the coating composition and the evaluation test results are shown in the following table.

Creating a base coat
Base coat production example 1
Using a polished steel plate as the base material, a weak solvent two-component paint (Hypon Fine Primer II, manufactured by Nippon Paint Co., Ltd.) is applied to the dry film thickness of 50 μm by air spray, and dried for one day. Production Example 1 was obtained.

Low-temperature initial water resistance test On the above-mentioned base coating film, the aqueous paint prepared above was applied with a brush in an environment of 5 ° C so that the coating amount was 120 g / m ^2, and dried at 5 ° C for 3 hours. . The prepared coating film was immersed in water at 5 ° C. for 16 hours, and immediately after pulling up, the appearance of the coating film was visually evaluated in accordance with JIS K5600-8-2, and the density and size of the generated coating film swelling. The evaluation was described with grades 0 to 5 and 1 to 5, respectively. Tables 3 and 4 list in density / size form. Each grade 2 or less was judged good and 3-5 was judged bad. When the density was 0, there was no swelling of the coating film, so the size was represented by “−”.

Density 0: No coating film swelling occurs.
1: The area of the part of the coating film swelling relative to the test coating film is judged to be less than 1%.
2: The area of the part of the coating film swelling relative to the test coating film is determined to be 1% or more and less than 3%.
3: The area of the coating film swelling portion relative to the test coating film is determined to be 3% or more and less than 7%.
4: The area of the coating film swelling portion relative to the test coating film is determined to be 7% or more and less than 30%.
5: It is judged that the area of the part of the coating film swelling with respect to a test coating film exceeds 30%.

Size 1: The diameter of the coating film swelling is less than 0.5 mm.
2: A coating film swelling having a diameter of 0.5 mm or more and less than 1 mm exists.
3: A coating film swelling having a diameter of 1 mm or more and less than 2 mm exists.
4: A coating film swelling having a diameter of 2 mm or more and less than 3 mm exists.
5: A coating film swelling having a diameter of 3 mm or more exists.

Undercoat film production examples 2 to 7
A polished steel plate was used as a base material, and a weak solvent two-component paint (Hypon Fine Primer II manufactured by Nippon Paint Co., Ltd.) was applied as a rust preventive paint by air spraying to a dry film thickness of 50 μm and dried for one day. Next, various paints shown in Table 2 were applied by brushing to a dry film thickness of 60 μm to obtain base coating film production examples 2 to 7, respectively.

Undercoat film production examples 8 to 13
Undercoating film production examples 8 to 13 (after coating each of the undercoating film production examples 2 to 7), the articles to be coated were deteriorated for 3,000 hours by accelerated weather resistance (xenon arc lamp method) according to JIS K5600-7-7. (Old paint film) was obtained.

Water-resistant swelling test The surface of each of the above-mentioned undercoats was wiped from the surface, and the water-based paint prepared above was brush-coated to a dry film thickness of 60 μm. After painting, it was cured for 7 days in a constant temperature and humidity room at 23 ° C. and a humidity of 50%. Thereafter, a submersion test was started under the same environment. It was lifted from the water 7 days after the immersion. Immediately after the pulling up, the appearance of the coating film was visually evaluated in accordance with JIS K5600-8-2, and the density and size of the generated coating film swelling were evaluated with grades 0 to 5 and 1 to 5, respectively. . Tables 3 and 4 list in density / size form. Each grade 2 or less was judged good and 3-5 was judged bad. When the density was 0, there was no swelling of the coating film, so the size was represented by “−”. In addition, the density grade (0-5) and magnitude | size grade (1-5) of the generated coating film swelling are the same as the above.

Secondary adhesion test A grid tape peeling test (secondary adhesion test) was carried out 5 minutes after the determination of the water-resistant swelling test. Hold the cutting blade of the cutter knife (NT cutter S type, A type, or equivalent) at 30 degrees on the coated plate that has been subjected to the water-proof blister test, and provide parallel lines at intervals of 2 mm to reach the substrate. Eleven lines were drawn, and 11 parallel lines with an interval of 2 mm perpendicular to the parallel lines were drawn to form 100 grids on the coating film. After the adhesive tape (industrial cellophane tape manufactured by Nichiban Co., Ltd.) is uniformly crimped with fingertips on this grid so that no air bubbles remain, hold the edge of the adhesive tape and make an angle of 60 degrees with the coating surface. The tape was peeled off from the coated surface, and the presence or absence of peeling of 100 grids was visually evaluated according to the following criteria.

0: The edges of the grid cut are completely smooth, and no peeling is confirmed.
1: Although peeling is confirmed at the intersection of the grid cut, the area of the peeling portion is less than 5% of the entire coating film.
2: The area of the peeled portion is 5% or more and less than 15% with respect to the entire coating film.
3: The area of the peeled portion is 15% or more and less than 35% with respect to the entire coating film.
4: The area of the peeled portion is 35% or more and less than 65% with respect to the entire coating film.
5: The area of the peeled portion is 65% or more with respect to the entire coating film.

A sealer (aqueous cation sealer, Nippon Paint Co., Ltd.) was applied to the slate plate of the water permeability test with a roller. On the next day of coating, the prepared aqueous coating composition was applied with a brush so that the dry film thickness was 60 μm. After painting, it was cured for 14 days in a constant temperature and humidity room at 23 ° C. and 50% temperature. Then, the water permeability test was started under the same environment. The water permeability test method and evaluation criteria were carried out in accordance with the water permeability test B method described in JIS A 6909. Specifically, a painted plate cured for 14 days is held horizontally, and a funnel with a caliber of 75 mm is placed upside down on the painted plate, and the periphery of the caliber is fastened to the test plate using a silicone sealing material. , Left for 48 hours. A 0.05 ml measuring pipette (capacity 5 ml) was connected to the top of the funnel foot using a rubber tube. Water at 23 ° C. was added so that the height of the water surface was 250 mm from the test plate and left for 24 hours. The difference between the scale of the water pipette immediately after the water was added and the scale of the water pipette pipette after standing for 24 hours was determined.

Examples 2-15, 18, Reference Examples 1-3 and Comparative Examples 1-8
A coating material was prepared in the same manner as in Example 1 except that the coating composition was changed as shown in Tables 3 and 4. Thereafter, in the same manner as in Example 1, a low temperature initial water resistance test, a water swell test, and a secondary adhesion test were performed. And a water permeability test was conducted. The results obtained are shown in Tables 3 and 4.

  As is clear from the above examples, the coating material according to claim 1 is excellent in low-temperature initial water resistance, water resistance, and secondary adhesion.

  Comparative Examples 1 and 2 are examples in which no chain transfer agent is used, water permeability is low, and depending on the base, water resistance and secondary adhesion are poor. Comparative Example 3 is an example in which the blending amount of DAAM is 4% by mass or less with respect to the total mass of the monomer, the water permeability is low, and both the water-resistant swelling and the secondary adhesion are rust-prevented (Ground Production Example 1). ) Except in the case of. Comparative Example 4 is an example in which the amount of DAAM is more than 40% by mass with respect to the total mass of the monomers, and the water permeability value is very high, and water resistance and secondary adhesion are still not good. Comparative Example 5 is an example that does not contain the hydrazine and / or hydrazide derivative (B) that is a crosslinking agent, and none of the low-temperature initial water resistance, water resistance, and secondary adhesion is good. Comparative Example 6 is an example not containing the water-based urethane polymer of component (C), and depending on the type of the base coating film, the water resistance and secondary adhesion are not good. Comparative Example 7 is a case where the aqueous emulsion A described in Patent Document 1 is used. This aqueous emulsion A is prepared without using a chain transfer agent. In this example, depending on the base, water resistance and secondary adhesion are poor. In Comparative Example 8, the content of the hydrazine and / or hydrazide derivative (B) is one hydrazine and / or hydrazide derivative with respect to 1 equivalent of diacetone (meth) acrylamide (a) used for the polymerization of the aqueous emulsion (A). This is an example in which the equivalent of the hydrazino group (B) is more than 2 equivalents, and the low-temperature initial water resistance is poor.

  The present invention provides a room temperature curable water-based coating composition having excellent adhesion to a base. The paint of the present invention is evaluated in terms of adhesion (secondary adhesion) with the base coat even when directly applied to the base coat or under high humidity conditions such as exposure to long-term rainfall. Adhesion) is maintained.

Claims (3)

(A) diacetone (meth) acrylamide, and (b) an unsaturated monomer copolymerizable with the component (a),
An aqueous emulsion (A) obtained by emulsion polymerization of a monomer mixture in which the amount of component (a) is 4 to 40% by mass with respect to the total monomer mass in the presence of a chain transfer agent,
Hydrazine and / or hydrazide derivative (B), and aqueous urethane polymer (C),
A room temperature curable water-based coating composition comprising:
The content of the hydrazine and / or hydrazide derivative (B) is hydrazine and / or hydrazide derivative (B) with respect to 1 equivalent of diacetone (meth) acrylamide (a) used for the polymerization of the aqueous emulsion (A). the amount der the equivalent of hydrazino group is less than 2 equivalents included in is,
The amount of the chain transfer agent is within the range of 100 / 0.1 to 100 / 3.0 in the ratio of the mass of the monomer mixture (the sum of the components (a) and (b)) / the mass of the chain transfer agent. And
The amount of the aqueous urethane polymer (C) is in the range of 1/100 to 50/100 in terms of the ratio of the nonvolatile content of the aqueous urethane polymer (C) / the nonvolatile content of the aqueous emulsion (A).
A room temperature curable aqueous coating composition. The hydrazide derivative has the following chemical formula:

The room temperature curable aqueous coating composition according to claim 1, which is a dihydrazide compound represented by the formula: The chain transfer agent is lauryl mercaptan, n-butyl mercaptan, t-butyl mercaptan, dodecyl mercaptan, octyl mercaptan, 2-ethylhexyl thioglycolate, 2-methyl-5-tert-butylthiophenol, tetrabromide The room-temperature-curable aqueous coating composition according to claim 1 or 2 , which is one or more selected from the group consisting of carbon and α-methylstyrene dimer.