JP2008231188A - One-pack type aqueous coating agent, its manufacturing method and coated material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one-pack type coating agent which excels in adhesion to a plastic base material and a topcoat and metallic pigment dispersibility and excels in water resistance and moisture resistance as well, its manufacturing method, and a coated material. <P>SOLUTION: The one-pack type coating agent is obtained by dispersing resin particles containing a terminal hydrazine structure-containing aqueous polyurethane (A) and a carbonyl group-containing vinyl polymer (B) into an aqueous medium, and the above aqueous polyurethane (A) is obtained by reacting a diisocyanate (a1) with a diol (a2) containing a polycarbonate diol (a21) and a carboxyl group-containing diol (a22) to obtain a polyurethane prepolymer (a) and thereafter performing neutralization of the polyurethane prepolymer (a) with a basic substance, chain extension with a hydrazine compound, and mixing with water, and the above diol (a2) contains 70-99 wt.% polycarbonate diol (a21). Its manufacturing method and the coated product are disclosed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a one-part aqueous coating agent, a method for producing the same, and a coated product. More specifically, the present invention relates to performance required as a coating composition for a cellular phone casing and an automobile parts casing, The present invention relates to a one-pack type aqueous coating agent capable of forming a film excellent in adhesion to top coating, (warm) water resistance, moisture resistance, and metal pigment (aluminum) dispersibility.

  Conventionally, the solvent type has been the mainstream coating agent used in these applications, but recently, in order to reduce the amount of solvent used in accordance with various laws and regulations including VOC, acrylic emulsion, urethane dispersion, etc. Attempts have been made to replace such aqueous resins. Among them, radicals containing a carbonyl group-containing radically polymerizable unsaturated monomer in the presence of a terminal hydrazine structure-containing aqueous polyurethane obtained by neutralizing a polyurethane prepolymer with a basic substance and chain extension with a hydrazine compound. An aqueous coating composition obtained by radical polymerization of a polymerizable unsaturated monomer is known as an aqueous coating composition having performances of an acrylic resin and a urethane resin (for example, Patent Document 1 and Patent Document). 2).

  These aqueous coating compositions described in Patent Document 1 and Patent Document 2 are excellent in adhesion to various plastic substrates and various top coat films, metallic pigment dispersibility, etc., but have sufficient moisture resistance and water resistance. There is a problem that is not.

JP-A-1-301762 JP 9-316394 A

  The object of the present invention is to provide excellent adhesion to various plastic substrates, adhesion to various top coats including UV curable resins, and dispersibility of metallic pigments such as aluminum pigments, and also water resistance and moisture resistance. It is to provide a one-pack type coating agent excellent in properties, a production method thereof, and a coated product.

  As a result of intensive investigations to solve the above problems, the present inventors have neutralized a polyurethane prepolymer obtained by using a diol containing 70 to 99% by weight of a polycarbonate diol with a basic substance and a chain with a hydrazine compound. One-part aqueous coating in which resin particles containing terminal hydrazine structure-containing aqueous polyurethane (A) and carbonyl group-containing vinyl polymer (B) obtained by mixing elongation and water are dispersed in an aqueous medium The agent is a one-part coating with excellent adhesion to plastic substrates, adhesion to various topcoats including UV curable resins, and excellent dispersibility of metallic pigments, as well as excellent water resistance and moisture resistance. For example, it is suitable for applications such as a one-part aqueous coating agent for plastic base coats, and this one-part type The functional coating agent includes diisocyanates (a1) and diols (a2) containing polycarbonate diol (a21) and carboxyl group-containing diol (a22) in a range in which the content of polycarbonate diol (a21) is 70 to 99% by weight. ) To obtain a polyurethane prepolymer (a), and then a terminal obtained by neutralizing the obtained polyurethane prepolymer (a) with a basic substance, chain extension with a hydrazine compound, and mixing with water. Easy by radical polymerization of vinyl monomers (b) containing carbonyl group-containing vinyl monomers (b1) in the presence of hydrazine structure-containing aqueous polyurethane (A) and emulsifier (C). And the one-part aqueous coating agent is applied to a plastic substrate and cured. It was found that the coated product is a coated product having a cured coating film excellent in adhesion to articles, adhesion to the top coat, and dispersibility of the metallic pigment, and also excellent in water resistance and moisture resistance. The invention has been completed.

  That is, the present invention is a one-pack type aqueous coating agent in which resin particles containing a terminal hydrazine structure-containing aqueous polyurethane (A) and a carbonyl group-containing vinyl polymer (B) are dispersed in an aqueous medium, The terminal hydrazine structure-containing aqueous polyurethane (A) is reacted with a diisocyanate (a1), a diol (a2) containing a polycarbonate diol (a21) and a carboxyl group-containing diol (a22) to react with a polyurethane prepolymer (a). Is obtained, and is obtained by subjecting the obtained polyurethane prepolymer (a) to neutralization with a basic substance, chain extension with a hydrazine compound and mixing with water, and the diols (a2). ) Contains 70 to 99% by weight of polycarbonate diol (a21). There is provided a one-aqueous coating agent to.

  The present invention also relates to diisocyanates (a1) and diols containing polycarbonate diol (a21) and carboxyl group-containing diol (a22) in a range where the content of polycarbonate diol (a21) is 70 to 99% by weight ( It is obtained by reacting a2) to obtain a polyurethane prepolymer (a) and then neutralizing the obtained polyurethane prepolymer (a) with a basic substance, chain extension with a hydrazine compound, and mixing with water. Radical polymerization of vinyl monomers (b) containing carbonyl group-containing vinyl monomers (b1) in the presence of terminal hydrazine structure-containing aqueous polyurethane (A), emulsifier (C) and water. The present invention provides a method for producing a one-part aqueous coating agent.

  Furthermore, the present invention provides a coated article obtained by applying a one-component aqueous coating agent to a plastic substrate and curing it.

  According to the present invention, a one-part aqueous coating agent having excellent adhesion to a plastic substrate, adhesion to various top coats including an ultraviolet curable resin, metallic pigment dispersibility, water resistance, and moisture resistance; Can provide paint.

  The terminal hydrazine structure-containing aqueous polyurethane (A) used in the present invention is obtained by reacting a diisocyanate (a1) with a diol (a2) containing a polycarbonate diol (a21) and a carboxyl group-containing diol (a22). After obtaining the polymer (a), an aqueous polyurethane obtained by neutralizing the obtained polyurethane prepolymer (a) with a basic substance, chain extension with a hydrazine compound and mixing with water, and It is an aqueous polyurethane obtained by using 70 to 99% by weight of the polycarbonate diol (a21) as the diol (a2). Especially, it is excellent in water resistance and moisture resistance, and also in dispersion stability in water. Since an excellent one-component aqueous coating agent is obtained, the diols (a ) Aqueous polyurethane obtained by using what polycarbonate diol (a21) containing 80 to 97 wt% is preferred as.

  Examples of the diisocyanates (a1) include aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates. Examples of these are 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4- Diphenylmethane diisocyanate, phenylene diisocyanate, xylylene diisocyanate, tetramethylene diisocyanate, lysine diisocyanate, 1,4-cyclohexylene diisocyanate, 4,4-dicyclohexylmethane diisocyanate, 3,3-dimethyl-4,4-biphenylene diisocyanate 3,3-dimethoxy-4,4-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,6-tetrahydronaphthalene diisocyanate, isophorone dii Cyanate and the like.

  Examples of the polycarbonate diol (a21) contained as an essential component in the diol (a2) include diols such as 1,4-butanediol, 1,6-hexanediol, and diethylene glycol, methyl carbonate, Examples include dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate, compounds obtained by reaction with phosgene, and the like, and those having a weight average molecular weight of 500 to 5,000 are usually used. Among these polycarbonate diols (a21), since a one-part aqueous coating agent having excellent resistance to hot water adhesion and moisture resistance can be obtained, a compound obtained by reaction of diols with methyl carbonate and / or ethyl carbonate is obtained. preferable. Moreover, since the synthesis | combination of a polyurethane prepolymer is easy, it is preferable that it is 800-2,500 as a weight average molecular weight of polycarbonate diol (a21).

  The polycarbonate diol (a21) is a component necessary for making the one-component aqueous coating agent of the present invention exhibit water resistance and moisture resistance, and the amount used thereof is the polycarbonate diol (a21 in the diol (a2)). ) Content of 70 to 99% by weight, and preferably 80 to 97% by weight. When the content of the polycarbonate diol (a21) in the diol (a2) of the polycarbonate diol (a21) is less than 70% by weight, the water resistance and the moisture resistance are lowered. When exceeding, since the usage-amount of carboxyl group-containing diol (a22) decreases and it becomes difficult to obtain the terminal hydrazine structure containing aqueous polyurethane (A) which is excellent in the dispersion stability with respect to water, neither is preferable.

  Next, the carboxyl group-containing diol (a22) is not particularly limited, and any of various carboxyl group-containing diols can be used. Among them, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2 , Dimethylol monocarboxylic acids such as 2-dimethylol valeric acid are preferred. These carboxyl group-containing glycols (a22) may be reacted directly with diisocyanates in combination with the polycarbonate diol (a21), or may be reacted with diisocyanates in combination with other diols (a23). You may use for. The content ratio of the carboxyl group-containing diol (a22) in the diols (a2) is an aqueous polyurethane containing a terminal hydrazine structure having an average particle diameter of 20 to 200 nm, which is excellent in dispersion stability in water, hot water adhesion, and water resistance (A ) Is obtained, the acid value of the polyurethane prepolymer (a) is preferably in the range of 10 to 40 mgKOH / g, and more preferably in the range of 15 to 30 mgKOH / g.

  Examples of other diols (a23) other than these essential diols include low molecular weight glycols, polyether glycols, polyester glycols, etc., and these may be used alone or in combination with polyether glycols or polyesters. Low molecular weight glycols may be used in combination with glycols.

  Here, as the low molecular weight glycols, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, octanediol, Examples include tricyclodecane dimethylol, hydrogenated bisphenol A, and cyclohexanedimethanol. Two or more of these may be mixed. Of these, glycols having 4 or less carbon atoms are particularly preferred.

  Examples of polyether glycols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like.

  Polyester glycols may be those obtained by reacting a glycol component and a dicarboxylic acid component, and can be easily produced by various methods. For example, polyester glycols can be obtained by esterification reaction of low molecular weight glycols or high molecular weight glycols with dicarboxylic acid, or transesterification reaction of low molecular weight glycols or high molecular weight glycols with lower alkyl ester of dicarboxylic acid. Can be manufactured.

  The dicarboxylic acid or the lower alkyl ester of the dicarboxylic acid used here is not particularly limited, and examples thereof include isophthalic acid, terephthalic acid, succinic acid, adipic acid, malonic acid, sebacic acid, and azelaic acid. Furthermore, lower alkyl esters of these dicarboxylic acids are also included. These dicarboxylic acids are used alone or in combination. In the present invention, when an unsaturated dicarboxylic acid is used as the dicarboxylic acid, the terminal hydrazine structure-containing aqueous polyurethane (A) and the carbonyl group-containing vinyl polymer (B) are polymerized when the carbonyl group-containing vinyl polymer (B) is polymerized. This is preferable because the vinyl polymer (B) is copolymerized and the functional connection between the two becomes stronger. Examples of the unsaturated dicarboxylic acid that can be used at this time include itaconic acid, maleic acid, and fumaric acid. Of these, itaconic acid is preferred from the viewpoint of excellent radical polymerizability.

  Examples of the reaction for producing the polyurethane prepolymer (a) from the above components include dioxane, acetone, methyl ethyl ketone, N-methylpyrrolidone, tetrahydrofuran and the like, which are inert to isocyanate groups and have a high affinity for water. Among these, it is desirable to carry out under a temperature condition of 20 to 120 ° C, preferably 30 to 100 ° C.

  The urethane prepolymer (a) thus obtained is then subjected to neutralization with a basic substance, chain extension with a hydrazine-based compound, and mixing with water, and thereby the terminal hydrazine structure-containing aqueous polyurethane (A) and can do. The organic solvent used for the reaction may be removed by various methods as necessary. The order of neutralization with the basic substance of the urethane prepolymer (a), chain extension with the hydrazine-based compound and mixing with water, except for the case where neutralization with the basic substance is performed after mixing with water. Although not limited, for example, (1) a method of neutralizing a urethane prepolymer (a) with a basic substance, mixing with water, and then chain-extending with a hydrazine compound, (2) urethane prepolymer ( a) a method in which neutralization with a basic substance in a) and mixing with water are simultaneously performed, followed by chain extension with a hydrazine compound; (3) neutralization with a basic substance in the urethane prepolymer (a) and a hydrazine compound; (4) A chain pre-extension of the urethane prepolymer (a) with a hydrazine compound, followed by neutralization with a basic substance, (5) A method in which the urethane prepolymer (a) is chain-extended with a hydrazine-based compound and then neutralized with a basic substance and mixed with water at the same time. Since the terminal hydrazine structure-containing aqueous polyurethane (A) can be easily produced, the methods (1), (2) and (3) are preferable, and the methods (2) and (3) are more preferable. In the method (2), a method in which the urethane prepolymer (a) and an aqueous solution of a basic substance are mixed, and then an aqueous solution of a hydrazine compound is mixed to extend the chain, and in the method (3), A method of simultaneously mixing the urethane prepolymer (a), an aqueous solution of a basic substance and an aqueous solution of a hydrazine-based compound is preferable.

  Examples of the basic substance used as the neutralizing agent include trimethylamine, triethylamine, tri-n-propylamine, tributylamine, potassium hydroxide, ammonia and the like. These can be used as an aqueous solution as necessary, as described above.

  Although it does not specifically limit as a hydrazine type compound used as a chain extender, For example, a hydrazine, ethylene-1, 2- dihydrazine, propylene- 1, 3- dihydrazine, butylene- 1, 4- dihydrazine Etc. These can be used as an aqueous solution as necessary, as described above.

  Moreover, as a chain extender which can be used by this invention, not only a hydrazine type compound but the other chain extender generally used as a chain extender of urethane prepolymer can also be used together partially.

Examples of such other chain extenders include, but are not limited to, polyols such as ethylene glycol and propylene glycol; ethylenediamine, propylenediamine, hexamethylenediamine, tolylenediamine, xylylenediamine, diphenyldiamine, diaminocyclohexyl Examples thereof include aliphatic diamines such as methane, piperazine, 2-methylpiperazine, and isophoronediamine, alicyclic diamines, and aromatic diamines. When such other chain extenders are used in combination, urethane prepolymer (a) It is a requirement of the invention that when the chain is extended, the chemical structure of —NHNH ₂ is retained at the end of the polymer molecule. By maintaining this chemical structure, it can be functionally linked to the carbonyl group in the carbonyl group-containing vinyl polymer (B).

  Next, the carbonyl group-containing vinyl polymer (B) contained in the dispersed resin particles together with the terminal hydrazine structure-containing aqueous polyurethane (A) is a carbonyl group in the vinyl polymer (B) at the time of film formation. Reacts with the hydrazine structure in the aqueous polyurethane (A) to form a cross-linked structure, thereby making it possible to develop good strength and solvent resistance of the cured product.

  The carbonyl group-containing vinyl copolymer (B) may be a polymer obtained from vinyl monomers (b) containing a carbonyl group-containing vinyl monomer (b1), and may contain a carbonyl group. Even if it is a homopolymer of a vinyl monomer (b1), it may be a copolymer of a carbonyl group-containing vinyl monomer (b1) and another vinyl monomer (b2). Since the content rate of a carbonyl group can be adjusted, it is preferable that it is a copolymer of a carbonyl group-containing vinyl monomer (b1) and another vinyl monomer (b2).

  As the content of the carbonyl group-containing vinyl monomer (b1) in the vinyl monomers (b), a one-component aqueous coating agent that exhibits an appropriate crosslinking density and good film-forming properties is obtained. Therefore, it is preferably 0.5 to 5.0% by weight, and since a one-part aqueous coating agent that exhibits good water resistance and solvent resistance is obtained, 1.0 to 3.0% by weight is obtained. % Is more preferable.

  The method for producing such a carbonyl group-containing vinyl polymer (B) is not particularly limited, but in the presence of the terminal hydrazine structure-containing aqueous polyurethane (A), preferably in the presence of the emulsifier (C). And a method of polymerizing the vinyl monomers (b) containing the carbonyl group-containing vinyl monomer (b1) is preferable. According to this method, it becomes easy to form composite particles in which the terminal hydrazine structure-containing aqueous polyurethane (A) and the carbonyl group-containing vinyl polymer (B) are present in the same dispersed particles.

  The carbonyl group-containing vinyl monomer (b1) used here is a monomer containing a keto group, and does not include a compound having only an ester bond or a carboxyl group. Examples of the carbonyl group-containing vinyl monomer (b1) corresponding to this include acrolein, diacetone acrylamide, vinyl methyl ketone, diacetone acrylate, acetonitrile acrylate and the like.

  Other vinyl monomers (b2) include, for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, nonyl methacrylate, lauryl methacrylate, stearyl methacrylate, and the like. Methacrylic acid esters; acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate; esters such as maleic acid, fumaric acid, itaconic acid Aromatic vinyl compounds such as styrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, chloromethylstyrene and vinyltoluene; heterocyclic vinyl compounds such as vinylpyrrolidone; acrylonitrile, methacrylonite Unsaturated nitriles such as conjugated diolefins such as butadiene and isoprene; divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, allyl methacrylate, diallyl phthalate, trimethylolpropane triacrylate, glyceryl diallyl ether , Polyfunctional vinyl monomers such as polyethylene glycol dimethacrylate and polyethylene glycol diacrylate; vinyl esters such as vinyl acetate and vinyl propionate; and vinylidene halide compounds such as vinyl chloride, vinylidene chloride and vinylidene fluoride It is done.

  Furthermore, for the purpose of imparting functionality to the carbonyl group-containing vinyl polymer (B), a vinyl monomer having a functional group other than the carbonyl group can be used in combination as the other vinyl monomer (b2).

  Examples of the vinyl monomer having a functional group other than a carbonyl group include amide monomers such as acrylamide, methacrylamide, and n-methylol methacrylamide as polarity imparting or crosslinkability imparting groups with an epoxy group or the like; Examples thereof include amino group-containing monomers such as dimethylaminoethyl acrylate and diethylaminoethyl acrylate, and monomers having a crosslinkability with a carboxyl group include hydroxy groups such as β-hydroxyethyl acrylate and β-hydroxyethyl methacrylate. Glycidyl group-containing monomer such as glycidyl acrylate and glycidyl methacrylate; acrylic acid, methacrylic acid, itaconic acid, maleic acid or half ester thereof; fumaric acid or half ester thereof, itaconic acid or half thereof Ester; Crotonic acid And carboxyl compounds such as p-vinylbenzoic acid. Further, as monomers having crosslinkability between silyl groups, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ- Examples thereof include silane compounds such as methacryloxypropyltrimethoxysilane.

  In the present invention, when the vinyl monomers (b) containing the carbonyl group-containing vinyl monomer (b1) are polymerized in the presence of the terminal hydrazine structure-containing aqueous polyurethane (A), the terminal hydrazine is used. Since the structure-containing aqueous polyurethane (A) can serve as a reaction site for the vinyl monomers (b), the emulsifier (C) is not always necessary, but it is preferable to carry out emulsion polymerization in the presence of the emulsifier (C). . As the usage-amount of an emulsifier (C), it is the range of 0.01-10 weight part normally with respect to 100 weight part of vinyl-type monomers (b), Preferably it is the range of 0.5-5.0. It is.

  As the emulsifier (C), various types can be used. For example, anionic emulsifiers such as sodium dodecylbenzene sulfate, sodium dodecylbenzenesulfonate, alkylaryl polyether sulfate; polyoxyethylene lauryl ether, Nonionic emulsifiers such as polyoxyethylene nonylphenyl ether and polyoxyethylene-polyoxypropylene block copolymers; cationic emulsifiers such as cetyltrimethylammonium bromide and laurylpyridinium chloride; and other reactive emulsifiers as appropriate Can be used.

  Moreover, it is also possible to use a water-soluble oligomer as a dispersing agent in the combined system with the emulsifier (C) instead of the above-mentioned emulsifier (C). Furthermore, it is also effective to use a water-soluble polymer substance such as polyvinyl alcohol or hydroxyethyl cellulose in combination with the emulsifier (C), or to add to the emulsion after polymerization.

  In the case of polymerization of vinyl monomers (b) containing a carbonyl group-containing vinyl monomer (b1), any of those used in usual emulsion polymerization can be used as the radical polymerization initiator. .

  Examples of these include potassium persulfate, ammonium persulfate, azobisisobutyronitrile, and their hydrochlorides, and organic peroxides such as cumene hydroperoxide and tert-butyl hydroperoxide are also required. Can be used according to. Furthermore, a redox initiator using a combination of these persulfates or peroxides with metal ions such as iron ions and reducing agents such as sodium sulfooxylate formaldehyde, sodium pyrosulfite, and L-ascorbic acid may be used. it can.

  Although the temperature at the time of emulsion polymerization is not specifically limited, The range currently performed by well-known emulsion polymerization may be sufficient, for example, the range of 30-90 degreeC is mentioned. The emulsion polymerization is carried out under normal pressure or under pressure when a gaseous vinyl monomer is used.

  The aqueous dispersion resin particles thus obtained may be resin particles containing the terminal hydrazine structure-containing aqueous polyurethane (A) and the carbonyl group-containing vinyl polymer (B). For example, the terminal hydrazine structure-containing aqueous polyurethane It may have a so-called core-shell structure having (A) as a shell and a carbonyl group-containing vinyl polymer (B) as a core, or a terminal hydrazine structure-containing aqueous polyurethane (A) and a carbonyl group. It may be one in which the vinyl polymer (B) is uniformly compatibilized, or one in which the abundance ratio of both polymers is different from the center of the resin particle to the surface so as to have a concentration gradient.

  The one-pack type aqueous coating agent of the present invention is an aqueous dispersion of resin particles containing the above-described carbonyl group-containing vinyl polymer (B) and terminal hydrazine structure-containing aqueous polyurethane (A).

  The ratio of the terminal hydrazine structure-containing aqueous polyurethane (A) to the carbonyl group-containing vinyl polymer (B) in the resin particles dispersed in the one-part aqueous coating agent of the present invention is determined depending on the plastic substrate and various top coat films. The one-part aqueous coating agent having excellent adhesion to the pigment, dispersibility of the metallic pigment, and the like is obtained, so that the solid content weight ratio (A / B) is preferably 10/90 to 90/10, and more preferably 20 / 80-40 / 60 is more preferable.

  The one-part aqueous coating agent of the present invention is used as a clear, or added with a pigment, as in the case of the production of a one-part aqueous coating agent using a conventional acrylic copolymer aqueous dispersion. Can be used as Pigments, fillers, aggregates, dispersants, wetting agents, thickeners and / or rheology control agents, antifoaming agents, plasticizers, film thickening aids, organic solvents, preservatives, pH adjusters, rust prevention Agents, antioxidants, ultraviolet absorbers and the like are selected and combined according to their respective purposes, and can be made into paints by ordinary methods.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited only to the following examples. In the following, parts and% are based on weight except for gloss retention.

Example 1
90 parts by mixing 500 parts of a polycarbonate diol (a polycarbonate diol having a weight average molecular weight of 2,000 obtained from diol and diethyl carbonate; the same applies hereinafter), 32 parts of 2,2-dimethylolpropionic acid and 147 parts of isophorone diisocyanate. The polyurethane prepolymer having an acid value of 25 mgKOH / g was obtained by raising the temperature to 0 ° C. and reacting at this temperature for 5 hours. While stirring this prepolymer at the same temperature, an aqueous amine solution prepared by dissolving 25 parts of triethylamine in 980 parts of ion-exchanged water was neutralized by pouring over 30 minutes, and after dispersion in water, 80% Chain extension was performed by adding 9 parts of a hydrazine aqueous solution. As a result, an aqueous polyurethane (A1) containing a terminal hydrazine structure having a nonvolatile content of 35% and an average particle size of 50 nm by the PAR-3 method was obtained.

  A four-necked flask was charged with 40 g of New Coal 707SF [anionic emulsifier manufactured by Nippon Emulsifier Co., Ltd., solid content 30%], 700 g of ion-exchanged water, and 857 g of aqueous polyurethane resin (A1). After raising the temperature to 80 ° C. in an air stream, 6.0 g of ammonium persulfate was added as a polymerization initiator.

  Next, 345 g of methyl methacrylate, 260 g of i-butyl methacrylate, 70 g of n-butyl acrylate, 15 g of methacrylic acid, 10 g of diacetone acrylamide, 40 g of New Coal 707SF, and 300 g of ion-exchanged water are mixed to prepare a monomer pre-emulsion. Then, this monomer pre-emulsion was dropped into the above four-necked flask over 3 hours. The reaction temperature at this time was kept at 80 ± 3 ° C. After the completion of the dropwise addition, the reaction was continued with stirring while maintaining the same temperature range for 2 hours, then cooled to room temperature (25 ° C.), 300 g of ion-exchanged water was added, and the pH was adjusted to 8 with 14% ammonia water. To a non-volatile content of 35.0%, a viscosity of 20 cps, and pH 8.5, a one-component aqueous coating agent (EM1).

  100 g of the obtained one-component aqueous coating agent (EM1), 16.3 g of butyl cellosolve, 14 g of 10% aqueous solution of Laponite RDS (a thickener manufactured by ROCKWOOD), 1.0 g of BYK-346 (a dispersant manufactured by Big Chemie) Surfynol 104BC (air products surface modifier) 1.0g mixture 2.0g, WJPU-75C (Toyo Aluminum Co., Ltd. aluminum pigment) 7.8g and butyl cellosolve 11.7g mixture 19.5g Thus, a metallic paint was prepared.

  The obtained metallic paint is applied to each of a polystyrene base material (PS base material), a polycarbonate base material (PC base material), and an ABS base material using a spray gun so as to have a dry film thickness of 15 μm. After drying with a dryer at 60 ° C. for 30 minutes, the sample was dried at room temperature (25 ° C.) for 3 days to obtain a test plate. Using the obtained test plate, adhesion, hot water adhesion, moisture resistance, FI value, and top coating adhesion were tested as follows. The results are shown in Table 1.

(Adhesion test)
A 10 × 10 cut with 1 mm square was made on the coating film surface of each test plate, a peel test with a cellophane tape was performed, and the number of remaining eyes was evaluated according to the following evaluation criteria.
Evaluation criteria A: 100
○: 85-99
Δ: 65-84
X: 35-64
XX: 34 or less

(Hot water adhesion test)
After each test plate was immersed in warm water at 40 ° C. for 24 hours, taken out and dried at room temperature for 2 hours, a peel test using cellophane tape was performed in the same manner as the adhesion test, and the remaining number of eyes was evaluated according to the following evaluation criteria. .
Evaluation criteria A: 100
○: 85-99
Δ: 65-84
X: 35-64
XX: 34 or less

(Moisture resistance test)
A test plate made of an ABS substrate whose gloss (60 ° gloss) has been measured in advance is stored in a thermostatic chamber at 65 ° C. and 98% humidity for 7 days, then the test plate is taken out and the gloss (OO ° gloss) is measured again. Then, the gloss retention rate of the coating film was calculated, and the softened state of the coating film was evaluated by touch.

(FI value: flop index measurement)
The FI value of a test plate made of an ABS substrate was measured using a measuring instrument (MODEL MA68B) manufactured by X-RITE.

(Top coat adhesion test)
Two-component acrylic urethane resin [Acridic WXU-880 / Barnock DN-950: manufactured by Dainippon Ink & Chemicals, OH / NC0 = 1/1 (molar ratio)] and ultraviolet light on a test plate made of ABS base material A curable resin (Unidic 17-824-9: manufactured by Dainippon Ink & Chemicals, Inc.) was applied by spraying so that the dry film thickness was 10 μm. However, the ultraviolet curable resin was cured by irradiation with an energy intensity of 10 Mrad with an electron beam irradiation apparatus (manufactured by Eye Electron Beam Co., Ltd.). Next, 10 × 10 cuts with 1 mm square were made on each cured coating film surface with a cutter, a peel test with a cellophane tape was performed, and the number of remaining eyes was evaluated according to the following evaluation criteria.
Evaluation criteria A: 100
○: 85-99
Δ: 65-84
X: 35-64
XX: 34 or less

Example 2
A terminal hydrazine structure-containing aqueous polyurethane (A2) in the same manner as in Example 1 except that 435 parts of polycarbonate diol and 65 parts of polytetramethylene ether glycol (weight average molecular weight 2,000) were used instead of 500 parts of polycarbonate diol. Got. The obtained aqueous polyurethane (A2) had a non-volatile content of 35% and an average particle size by the PAR-3 method of 50 nm.

  A one-component aqueous coating agent (EM2) and a metallic paint using this one-component aqueous coating agent (EM2) were prepared in the same manner as in Example 1 except that the obtained aqueous polyurethane (A2) was used. Further, in the same manner as in Example 1, adhesion, hot water adhesion, moisture resistance, FI value, and top coating adhesion were tested. The results are shown in Table 1.

Example 3
A terminal hydrazine structure-containing aqueous polyurethane (A3) in the same manner as in Example 1 except that 385 parts of polycarbonate diol and 115 parts of polytetramethylene ether glycol (weight average molecular weight 2,000) were used instead of 500 parts of polycarbonate diol. Got. The obtained water-based polyurethane (A3) had a nonvolatile content of 35% and an average particle size by the PAR-3 method of 50 nm.

  A one-part aqueous coating agent (EM3) and a metallic paint using this one-part aqueous coating agent (EM3) were prepared in the same manner as in Example 1 except that the obtained aqueous polyurethane (A3) was used. Further, in the same manner as in Example 1, adhesion, hot water adhesion, moisture resistance, FI value, and top coating adhesion were tested. The results are shown in Table 1.

Comparative Example 1
Instead of 500 parts of polycarbonate diol, 32 parts of 2,2-dimethylolpropionic acid and 147 parts of isophorone diisocyanate, 500 parts of polytetramethylene ether glycol (weight average molecular weight 2,000), 36 parts of 2,2-dimethylolpropionic acid A terminal hydrazine structure-containing aqueous polyurethane (RA1) was obtained in the same manner as in Example 1 except that 18 parts of neopentyl glycol and 206 parts of isophorone diisocyanate were used. The obtained water-based polyurethane (RA1) had a nonvolatile content of 35% and an average particle size by the PAR-3 method of 50 nm.

  A one-part aqueous coating agent (REM1) and a metallic paint using this one-part aqueous coating agent (REM1) were prepared in the same manner as in Example 1 except that the obtained aqueous polyurethane (RA1) was used. Further, in the same manner as in Example 1, adhesion, hot water adhesion, moisture resistance, FI value, and top coating adhesion were tested. The results are shown in Table 1.

Comparative Example 2
Terminal hydrazine structure-containing aqueous polyurethane (RA2) in the same manner as in Example 1 except that 350 parts of polycarbonate diol and 150 parts of polytetramethylene ether glycol (weight average molecular weight 2,000) were used instead of 500 parts of polycarbonate diol. Got. The obtained water-based polyurethane (RA2) had a nonvolatile content of 35% and an average particle size by the PAR-3 method of 50 nm.

  A one-part aqueous coating agent (REM2) and a metallic paint using this one-part aqueous coating agent (REM2) were prepared in the same manner as in Example 1 except that the obtained aqueous polyurethane (RA2) was used. Further, in the same manner as in Example 1, adhesion, hot water adhesion, moisture resistance, FI value, and top coating adhesion were tested. The results are shown in Table 1.

(Test results)
As can be seen from Table 1, the one-part aqueous coating agent of the present invention is more adhesive than the one-part aqueous coating agent of Comparative Examples 1 and 2 that do not satisfy the requirements of the invention, It has excellent adhesion to various topcoats including UV curable resins and dispersibility of metallic pigments, and also has water resistance and moisture resistance.

Claims (11)

A one-part aqueous coating agent in which resin particles containing a terminal hydrazine structure-containing aqueous polyurethane (A) and a carbonyl group-containing vinyl polymer (B) are dispersed in an aqueous medium, the terminal hydrazine structure-containing aqueous After the polyurethane (A) is reacted with a diisocyanate (a1), a diol (a2) containing a polycarbonate diol (a21) and a carboxyl group-containing diol (a22) to obtain a polyurethane prepolymer (a), The polyurethane prepolymer (a) is an aqueous polyurethane obtained by neutralization with a basic substance, chain extension with a hydrazine compound and mixing with water, and the diol (a2) is a polycarbonate diol (a21 ) In an amount of 70 to 99% by weight. Coating agent. The one-component aqueous coating agent according to claim 1, wherein the diol (a2) contains 80 to 97% by weight of the polycarbonate diol (a21). The one-pack type aqueous coating agent according to claim 1 or 2, wherein the polycarbonate diol (a21) is a compound obtained by a reaction of diols with methyl carbonate and / or ethyl carbonate. The one-pack type aqueous coating agent according to claim 1 or 2, wherein the polycarbonate diol (a21) is a polycarbonate diol having a weight average molecular weight of 800 to 2,500. The solid content weight ratio (A / B) of the terminal hydrazine structure-containing aqueous polyurethane (A) and the carbonyl group-containing vinyl polymer (B) is 10/90 to 90/10, and the carbonyl group-containing vinyl system The one-pack type aqueous coating agent according to claim 1 or 2, wherein the polymer (B) is a vinyl polymer containing 0.5 to 5% by weight of a component derived from a carbonyl group-containing vinyl monomer (b1). Diisocyanates (a1) and a diol (a2) containing a polycarbonate diol (a21) and a carboxyl group-containing diol (a22) are reacted in a range where the content of the polycarbonate diol (a21) is 70 to 99% by weight. After the polyurethane prepolymer (a) is obtained, the terminal hydrazine structure-containing aqueous solution obtained by neutralizing the obtained polyurethane prepolymer (a) with a basic substance, chain extension with a hydrazine compound derivative, and mixing with water. One-pack type characterized by radical polymerization of vinyl monomer (b) containing carbonyl group-containing vinyl monomer (b1) in the presence of polyurethane (A) and emulsifier (C) A method for producing an aqueous coating agent. The method for producing a one-component aqueous coating agent according to claim 6, wherein the diol (a2) contains 80 to 97% by weight of the polycarbonate diol (a21). The method for producing a one-component aqueous coating agent according to claim 6 or 7, wherein the polycarbonate diol (a21) is a compound obtained by a reaction of diols with methyl carbonate and / or ethyl carbonate. The method for producing a one-component aqueous coating agent according to claim 6 or 7, wherein the polycarbonate diol (a21) is a polycarbonate diol having a weight average molecular weight of 800 to 2,500. The weight ratio (A / b) of the solid content of the terminal hydrazine structure-containing aqueous polyurethane (A) and the vinyl monomers (b) is 10/90 to 90/10, and the vinyl monomers The method for producing a one-component aqueous coating agent according to claim 6 or 7, wherein the content of the carbonyl group-containing vinyl monomer (b1) in the class (b) is 0.5 to 5% by weight. A coated product obtained by applying the one-component aqueous coating agent according to any one of claims 1 to 5 to a plastic substrate and curing it.