JP2007002035A - Water-based resin composition, method for producing the same, and method for forming cured coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based resin composition capable of forming a cured coating film excellent in film properties by irradiation with an ultraviolet radiation and/or electron beams. <P>SOLUTION: The water-based resin composition is one prepared by dispersing resin particles in an aqueous medium, wherein the resin particles are ones which are obtained by dispersing an NCO-terminated prepolymer obtained by reacting an isocyanate with a long-chain polyol and a dimethylol fatty acid and neutralizing the product and subjecting the neutralized product to a chain extension reaction with a polyalkylenepolyamine and in which the content (C1) of the -COOH groups and/or -COO<SP>-</SP>groups derived from the dimethylol fatty acid is not less than 0.40 mmol/g, the content (C2) of structures derived from the imino groups of the polyalkylenepolyamine is not less than 0.02 mmol/g, and the ratio (C1)/(C2) between the contents (C1) and (C2) is 1 to 20. The method for forming the cured coating film comprises curing a coating film formed from the water-based resin composition by irradiation with an ultraviolet radiation and/or electron beams. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an aqueous resin composition and a method for producing the same, and a method for forming a cured coating film. More specifically, the present invention relates to an aqueous urethane resin composition that is cured by irradiation with ultraviolet rays and / or electron beams, and a method for producing the same. The present invention relates to a method for forming a cured coating film with such an aqueous resin composition.

In the field of paints and coatings, water-based resin compositions are used from the viewpoint of improving the working environment. Conventionally, what is described in the following patent documents 1 and 2 is known as a one-pack type water-based polyurethane resin composition.
The water-based polyurethane resin composition comprises an isocyanate group-terminated prepolymer obtained by reacting an isocyanate, a long-chain polyol, and a hydrophilic group-containing monomer in water after neutralization, and dispersed particles (prepolymer). It can be prepared by reacting with an extender such as polyamine.

  On the other hand, an acrylic polymerizable resin (radical polymerization type photocurable resin) is frequently used as a resin component constituting the ultraviolet curable resin composition.

However, cured coatings made from conventionally known aqueous polyurethane resin compositions, including those described in the following patent documents, are not fully satisfactory in coating properties such as solvent resistance and water resistance.
JP 2004-196836 A JP 2004-189877 A

An object of the present invention is to provide a urethane resin-based aqueous resin composition capable of forming a cured coating film having excellent coating film properties such as solvent resistance and water resistance by irradiation with ultraviolet rays and / or electron beams. It is to provide.
Another object of the present invention is to provide a method for suitably producing such an aqueous resin composition.
Still another object of the present invention is to provide a method capable of forming a cured coating film comprising a urethane resin having excellent coating film properties such as solvent resistance and water resistance.

The aqueous resin composition of the present invention is an aqueous resin composition in which resin particles are dispersed in an aqueous medium and cured by ultraviolet rays and / or electron beams. The resin particles include isocyanate, a long-chain polyol, and dimethylol. Resin particles synthesized by dispersing an isocyanate group-terminated prepolymer obtained by reacting with a fatty acid and then neutralizing in an aqueous medium, and by subjecting it to an extended reaction with a polyalkylene polyamine, the dimethylol fatty acid The content ratio (C1) of the carboxyl group (—COOH) and / or carboxylate group (—COO ⁻ ) derived from is 0.40 mmol / g or more, and is derived from the imino group (—NH—) of the polyalkylene polyamine. The content ratio (C2) of the structure (-N =) is 0.02 mmol / g or more, and the ratio of the content ratios Wherein the C1) / (C2) is a resin particle is 1 to 20.

  The production method of the present invention is a method for producing the aqueous resin composition of the present invention, wherein the isocyanate, the long-chain polyol, and the dimethylol fatty acid are reacted in a solvent or in the absence of a solvent and then neutralized, A step of obtaining an isocyanate group-terminated prepolymer; a step of dispersing the isocyanate group-terminated prepolymer in an aqueous medium and an extension reaction with a polyalkylene polyamine; the isocyanate, the long-chain polyol, the dimethylol fatty acid, and The ratio (c1) of the amount (mmol) of the dimethylol fatty acid used to the total amount (mass) of the polyalkylene polyamine used is 0.40 mmol / g or more; the isocyanate, the long-chain polyol, the dimethylol Of fatty acids and said polyalkylene polyamines The ratio (c2) of the imino group contained in the polyalkylenepolyamine used relative to the total dose (mass) is 0.02 mmol / g or more; the ratio (c1) / (c2) of the ratio is 1 to 20 It is characterized by being.

  The method for forming a cured coating film of the present invention is characterized by irradiating a coating film formed of the aqueous resin composition of the present invention with ultraviolet rays and / or electron beams.

(1) By irradiating the coating film made of the aqueous resin composition of the present invention with ultraviolet rays and / or electron beams, a cured coating film having excellent coating film properties such as solvent resistance and water resistance can be formed. .
(2) The coating film made of the aqueous resin composition of the present invention is cured by irradiation with ultraviolet rays and / or electron beams, and the coating film properties such as solvent resistance and water resistance are improved.
The curability of the coating film by irradiation with ultraviolet rays and / or electron beams is due to the specific urethane resin constituting the aqueous resin composition, and a polymerizable photocurable resin such as an acrylic polymerizable resin is used. Even when it is not contained in the aqueous resin composition, it is expressed (cured).
(3) According to the method for forming a cured coating film of the present invention, the coating film is cured by irradiation with ultraviolet rays and / or electron beams, and a cured coating film having excellent coating film properties such as solvent resistance and water resistance is obtained. Can be formed.

<Aqueous resin composition>
The composition of the present invention is a one-pack type aqueous resin composition in which resin particles are dispersed in an aqueous medium.

<Resin particles>
The resin particles constituting the composition of the present invention are prepared by dispersing an isocyanate group-terminated prepolymer obtained by reacting an isocyanate, a long-chain polyol, and a dimethylol fatty acid and then neutralizing it in an aqueous medium. It is a urethane resin particle synthesized by an extension reaction with an alkylene polyamine.

<Isocyanate>
As the “isocyanate” used for obtaining the resin particles, aliphatic isocyanate and alicyclic isocyanate are preferable.
As "aliphatic isocyanate", tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate, 2,2,4-trimethylhexamethylene Examples include -1,6-diisocyanate and 2,4,4-trimethylhexamethylene-1,6-diisocyanate.

  Examples of the “alicyclic isocyanate” include isophorone diisocyanate, cyclohexyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated trimethylxylylene diisocyanate, and the like.

  Furthermore, urethane-modified products, carbodiimide-modified products, allophanate-modified products, burette-modified products, uretdione-modified products, uretoimine-modified products, and isocyanurate-modified products of these isocyanates can also be used.

<Long chain polyol>
The “long-chain polyol” used to obtain the resin particles is not particularly limited, and is a polyether polyol, polyester polyol, polycarbonate polyol, polyolefin polyol, animal and plant polyol, polymer polyol, halogen-containing polyol, phosphorus-containing A polyol, a phenol base polyol, etc. can be mentioned. Of these, polycarbonate polyol is preferable because a resin excellent in abrasion resistance, hydrolysis resistance, weather resistance, and the like can be obtained.

“Polyether polyol” is a compound having two or more active hydrogens such as poly (oxyethylene) polyol, poly (oxypropylene) polyol, poly (oxytetramethylene) polyol, etc. It can be produced by adding a cyclic ether.
Examples of the “compound having two or more active hydrogens” used for the production of the polyether polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2,2-dimethyl-1,3- Propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, trimethylene glycol, triethylene glycol, tetramethylene glycol, hexa Short-chain diols such as methylene glycol, decamethylene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol and bisphenol A; short-chain triols such as glycerin, hexanetriol and trimethylolpropane; pentaerythritol ( Short chain tetraols such as tramethylol methane) and tetramethylol cyclohexane; 2,2,6,6-tetrakis (hydroxylmethyl) cyclohexanol, sorbitol (glucitol), mannitol, dulcitol (galactitol), sucrose, etc. 5-8 Polyols having one OH group; low molecular weight polyamines such as diethylenetriamine, ethylenediamine, propylenediamine, metaphenylenediamine, tolylenediamine, xylylenediamine, diphenylmethanediamine, and aniline; low such as monoethanolamine, diethanolamine, and triethanolamine A molecular amino alcohol etc. can be mentioned, These can be used individually or in combination of 2 or more types.
Examples of the “cyclic ether” to be added include alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, and tetramethylene oxide.

“Polyester polyol” can be produced by reacting a compound having two or more hydroxyl groups (polyhydric alcohol) with a compound having two or more carboxyl groups (polybasic acid) by a known method. it can.
Examples of the “compound having two or more hydroxyl groups” used for the production of the polyester polyol include the short-chain diol and the short-chain triol. These may be used alone or in combination of two or more. Can do.
Examples of the “compound having two or more carboxyl groups” used for the production of polyester polyol include adipic acid, malonic acid, succinic acid, tartaric acid, pimelic acid, sebacic acid, oxalic acid, phthalic acid, terephthalic acid, and isophthalic acid. Phthalic anhydride, azelaic acid, trimellitic acid, curtaconic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α, β-diethylsuccinic acid, hemimellitic acid, 1, 4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 4,4′-diphenylmethanedicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid 4,4′-diphenylisopropylidenedicarboxylic acid, 1,2-diphenoxy Examples thereof include tan-4 ′, 4 ″ -dicarboxylic acid, anthracene dicarboxylic acid, 2,5-pyridinedicarboxylic acid, diphenyl ketone dicarboxylic acid, and the like, and these can be used alone or in combination of two or more. .
Moreover, you may use the lactone-type polyester polyol obtained by ring-opening polymerization of lactone ((epsilon) -caprolactone, methyl valerolactone, etc.).

  Examples of the “polycarbonate polyol” include those obtained by dealcoholization reaction or dephenol reaction of the short chain diol and / or short chain triol and a low molecular carbonate (for example, ethylene carbonate, diethyl carbonate, diphenyl carbonate). it can.

  Examples of the “polyolefin polyol” include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, hydrogenated polyisoprene and the like.

  Examples of “animal and plant-based polyols” include castor oil-based polyols and silk fibroin.

  Examples of the “polymer polyol” include a polymer polyol obtained by reacting a polyether polyol and an ethylenically unsaturated monomer (for example, butadiene, acrylonitrile, styrene, etc.) in the presence of a radical polymerization catalyst.

  Examples of the “halogen-containing polyol” include those obtained by ring-opening polymerization of epichlorohydrin and trichlorobutylene oxide, those obtained by adding alkylene oxide to a brominated polyhydric alcohol, and the like. Can do.

  Examples of the “phosphorus-containing polyol” include those obtained by addition polymerization of alkylene oxide to phosphoric acid, phosphorous acid, organic phosphoric acid, and the like, and those obtained by adding alkylene oxide to polyhydroxypropylphosphine oxide.

  “Phenol-based polyol” includes a novolak resin obtained from phenol and formalin, a polyol obtained by reacting an alkylene oxide with a resole resin, and Mannich obtained by reacting a phenol with an alkanolamine and formalin with an alkylene oxide. A base polyol etc. can be mentioned.

The average molecular weight of the long-chain polyol is usually 500 or more, preferably 1,000 to 4,000.
The average number of functional groups of the long-chain polyol is preferably 1.5 to 3.0, and more preferably 1.7 to 2.5.
The hydroxyl value of the long-chain polyol is preferably 20 to 165 mgKOH / g, more preferably 23 to 140 mgKOH / g.

<Dimethylol fatty acid>
The “dimethylol fatty acid” used to obtain the resin particles imparts hydrophilicity to the isocyanate group-terminated prepolymer (and thus resin particles) obtained by the reaction with isocyanate, and the resin composition finally obtained is water-based. It is a hydrophilic group-containing monomer for making it. In addition, by using dimethylol fatty acid at a specific ratio described later, the coating film properties such as solvent resistance and water resistance in the formed cured coating film (coating film after irradiation with ultraviolet rays and / or electron beams) are improved. Can be made.

  Examples of the dimethylol fatty acid include dimethylol alkanoic acids such as dimethylol propionic acid (DMPA), dimethylol butanoic acid (DMBA), dimethylol pentanoic acid, and dimethylol nonanoic acid.

<Urethaneization reaction / neutralization treatment>
In order to obtain the aqueous resin composition (resin particles dispersed in an aqueous medium) of the present invention, first, the above-mentioned isocyanate, long-chain polyol, and dimethylol fatty acid are urethanated in a solvent or without solvent. After neutralizing, neutralize.

  Here, as the reaction solvent, acetone, ethyl acetate, butyl acetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 1-methoxypropyl-2-acetate, 2-butanone, 4-methyl-2-pentanone, Examples include cyclohexanone, propylene glycol diacetate, diethylene glycol methyl ether, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, N-methylpyrrolidone, and N-methylcaprolactam, and these may be used alone or in admixture of two or more. be able to.

  The reaction conditions (temperature / time) are, for example, 40 to 90 ° C. and 2 to 5 hours. Thereby, the isocyanate group terminal prepolymer containing a carboxyl group is obtained. The NCO content of the obtained prepolymer is preferably 1 to 20% by mass.

  Examples of the neutralizing agent used for the neutralization treatment include tertiary amines such as triethylamine (TEA), trimethylamine, triisopropylamine, tributylamine, triethanolamine, triisopropanolamine, N-methyldiethanolamine, N -Phenyldiethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine) and the like.

  Examples of the neutralization treatment method include a method of adding a neutralizing agent to the system after completion of the urethanization reaction. Thereby, at least a part of the isocyanate group-terminated prepolymer “containing a carboxyl group” becomes an isocyanate group-terminated prepolymer “containing a carboxylate (carboxylate group)”.

<Dispersion / extension reaction>
Next, the isocyanate group-terminated prepolymer obtained as described above is dispersed in an aqueous medium and subjected to an extension reaction with a polyalkylene polyamine. Thereby, the aqueous resin composition (resin particles dispersed in an aqueous medium) of the present invention is obtained.
In order to obtain an aqueous resin composition, the prepolymer may be dispersed in an aqueous medium and then the extension reaction may be performed, or the dispersion treatment and the extension reaction may be performed simultaneously.

The “polyalkylene polyamine” used in the reaction with the isocyanate group-terminated prepolymer (extension reaction) has the formula: NH ₂ — (R—NH) _n —H (wherein R is an alkylene group, and n is 2 or more) And has at least one imino group (—NH—) in the molecule.
By using this polyalkylene polyamine in a specific ratio described later, the coating film properties such as solvent resistance and water resistance in the formed cured coating film (coating film after irradiation with ultraviolet rays and / or electron beams) are improved. Can be made.

  Examples of such polyalkylene polyamines include diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), and pentaethylenehexamine (PEHA).

  The reaction conditions (temperature and time) for the extension reaction are, for example, 30 to 60 ° C. and 0.5 to 2 hours.

<Production conditions of aqueous resin composition>
In the aqueous resin composition of the present invention, an isocyanate, a long-chain polyol, and a dimethylol fatty acid are subjected to a urethanization reaction, followed by neutralization to obtain an isocyanate group-terminated prepolymer, and the prepolymer is dispersed in an aqueous medium. At the same time, it is produced by an extension reaction with a polyalkylene polyamine.

  In the present invention, the ratio of the amount of dimethylol fatty acid used (number of millimoles) to the total of the amount of use (mass) of isocyanate, long chain polyol, dimethylol fatty acid and polyalkylene polyamine (hereinafter referred to as “solid content mass”) ( c1) is 0.40 mmol / g or more, preferably 0.40 to 0.70 mmol / g, more preferably 0.45 to 0.55 mmol / g.

By making the ratio (c1) of the amount of dimethylol fatty acid used relative to the solid mass to 0.40 mmol / g or more, a carboxyl group (—COOH) and / or a carboxylato group (—COO ⁻ ) derived from the dimethylol fatty acid. Resin particles having a content ratio (C1) of 0.40 mmol / g or more can be obtained.

  When the ratio (c1) of the amount of dimethylol fatty acid used relative to the mass of the solid content is less than 0.40 mmol / g, the content ratio (C1) of carboxyl groups and / or carboxylato groups in the obtained resin particles is 0.00. Depending on the water-based resin composition in which such resin particles are dispersed at less than 40 mmol / g, the effect of improving coating film properties cannot be exhibited (see Comparative Examples 1 and 4 described later).

  In the present invention, the ratio (c2) of the imino group contained in the used polyalkylene polyamine to the solid mass is 0.02 mmol / g or more, preferably 0.02 to 1.00 mmol / g, more preferably Is 0.05 to 0.40 mmol / g.

  By making the ratio (c2) of the imino group contained in the used polyalkylene polyamine to 0.02 mmol / g or more with respect to the solid mass, the structure derived from the imino group (—NH—) (—N =) Resin particles having a content ratio (C2) of 0.02 mmol / g or more can be obtained.

  When the ratio (c2) of the imino group contained in the used polyalkylene polyamine with respect to the solid mass is less than 0.02 mmol / g, the content ratio of the structure derived from the imino group in the obtained resin particles ( Depending on the aqueous resin composition in which C2) is less than 0.02 mmol / g and such resin particles are dispersed, the effect of improving the physical properties of the coating film cannot be exhibited (see Comparative Examples 2 to 4 described later). ).

  In the present invention, the ratio [(c1) / (c2)] of the proportion (c1) of the dimethylol fatty acid used and the proportion (c2) of the imino group contained in the used polyalkylene polyamine is 1 to 20, preferably 1 to 10, more preferably 1 to 8.

By setting the ratio [(c1) / (c2)] to 1 to 20, resin particles having the content ratio [[C1) / (C2)] of 1 to 20 can be obtained.
When this ratio [(c1) / (c2)] is out of the range, the ratio of content in the obtained resin particles [(C1) / (C2)] is also out of the range, and such resin particles are dispersed. Depending on the water-based resin composition formed, the effect of improving the physical properties of the coating film cannot be exhibited (see Comparative Examples 2 to 4 described later).

  Resin particles obtained by a production method satisfying all the production conditions [(c1) ≧ 0.40 mmol / g, (c2) ≧ 0.02 mmol / g, 1 ≦ (c1) / (c2) ≦ 20] Has a content ratio (C1) of carboxyl group and / or carboxylate group derived from dimethylol fatty acid of 0.40 mmol / g or more, and a content ratio (C2) of structure derived from imino group of polyalkylene polyamine is 0.02 The ratio (C1) / (C2) of the content ratio is 1 to 20 at the mmol / g or more.

And according to the water-based resin composition of the present invention in which such resin particles are dispersed, the coating film formed thereby is irradiated with ultraviolet rays and / or electron beams, so that solvent resistance, water resistance, etc. A cured coating film excellent in physical properties of the coating film can be formed.
Here, the curability of the coating film by irradiation with ultraviolet rays and / or electron beams is due to the specific urethane resin (urethane resin obtained by the above production conditions) constituting the aqueous resin composition, and (meta) It is expressed even when a polymerizable photocurable resin such as an acrylic polymerizable resin containing an acryloyl group is not contained in the aqueous resin composition.

In the aqueous resin composition of the present invention, the average particle size of the resin particles is preferably 20 to 500 nm, and more preferably 50 to 400 nm.
The solid content (concentration) of the aqueous resin composition of the present invention is preferably 20 to 50% by mass, more preferably 25 to 45% by mass.
The viscosity (25 ° C.) of the aqueous resin composition of the present invention is preferably 10 to 500 mPa · s, more preferably 20 to 350 mPa · s.

<Optional component>
The aqueous resin composition of the present invention includes, as optional components, a radical polymerization photocurable resin (such as an acrylic polymerizable resin), a radical polymerization photoinitiator, a cationic polymerization photocurable resin, and a cationic polymerization light. Initiator, film-forming aid, colorant, light stabilizer, antioxidant, thermal polymerization inhibitor, leveling agent, surfactant, storage stabilizer, plasticizer, lubricant, solvent, filler, anti-aging agent, wetting A property improving agent, a coating surface improving agent, a flame retardant and the like may be contained.

<Method for forming cured coating film>
In the forming method of the present invention, the coating film formed of the aqueous resin composition of the present invention is irradiated with ultraviolet rays and / or electron beams.
Specifically, the aqueous resin composition of the present invention is applied to a substrate, the coating film is dried to remove moisture, and then the coating film is irradiated with ultraviolet rays and / or electron beams.

Here, the substrate is not particularly limited, and examples thereof include metal, plastic, paper, wood, glass, ceramic, and mortar.
The application (coating) method is not particularly limited, and examples thereof include spraying, roll coating, curtain flow coating, brush coating, and dipping.
As drying conditions of a coating film, it is set as 2 hours-7 days at 0-80 degreeC, for example.

  In the formation method of the present invention, it is effective to irradiate light in the ultraviolet region, particularly 200 to 300 nm. Examples of the light source for irradiating with ultraviolet rays include a mercury lamp and a metal halide lamp.

<Example 1>
In accordance with the formulation shown in Table 1 below, 220 g of polyol A, 147 g of isocyanate X, 28 g (209 mmol) of dimethylolpropionic acid, 153 g of acetone, and 100 ppm of dioctyltin dilaurate (DOTDL) are charged in a reaction vessel, and the mixture is 4 at 50 ° C. The urethanization reaction was performed over time to obtain an isocyanate group-terminated prepolymer containing a carboxyl group.
Subsequently, neutralization treatment was performed by adding 17 g of a neutralizing agent (TEA) to this system (prepolymer solution), and 80% by mass of the isocyanate group-terminated prepolymer containing a carboxyl group was converted to a carboxylate (carboxylate). Group) containing isocyanate group-terminated prepolymer.

Next, an aqueous solution of an extender consisting of 747 g of water (dispersion medium) and 16 g (155 mmol) of diethylenetriamine was added to the acetone solution of the isocyanate group-terminated prepolymer subjected to neutralization treatment for 2 minutes while stirring (200 rpm). The prepolymer was emulsified and dispersed at 30 to 40 ° C. for 1 hour, and a chain extension reaction was performed. Thereafter, acetone is evaporated and removed under reduced pressure conditions of 40 to 60 ° C. and 10 to 20 kPa to disperse the resin particles in water. The resin composition having a solid content of 35% (the aqueous resin composition of the present invention). Got.
The obtained aqueous resin composition had a viscosity (25 ° C.) of 300 mPa · s, an average particle size of the resin particles of 122 nm, and a pH of 7.8.

In this example, the use ratio (c1) of dimethylolpropionic acid to the total solid mass (411 g) is 0.51 (= 209/411) mmol / g.
Moreover, the ratio (c2) of the imino group contained in the diethylenetriamine with respect to the total solid mass is 0.38 (= 155/411) mmol / g.
The value of the ratio [(c1) / (c2)] is 1.3.

<Examples 2-3>
In accordance with the formulation shown in Table 1 below, polyol, isocyanate X, dimethylolpropionic acid, acetone, and DOTDL are charged into a reaction vessel, and a urethanization reaction is carried out in the same manner as in Example 1 to contain a carboxyl group. An isocyanate group-terminated prepolymer was obtained, and neutralized by adding a neutralizing agent (TEA).
Next, an aqueous solution of an extender containing diethylenetriamine is added to an acetone solution of an isocyanate group-terminated prepolymer that has been subjected to neutralization treatment, and the prepolymer is emulsified and dispersed in the same manner as in Example 1 and a chain extension reaction is performed. Thereafter, acetone was removed by evaporation to obtain a resin composition in which resin particles are dispersed in water (the aqueous resin composition of the present invention). About each of the obtained water-based resin composition, the ratio (c2) of the imino group contained in the used diethylenetriamine with respect to the total mass of dimethylolpropionic acid with respect to the total mass of the solid content (c1), the ratio of the two Table 1 shows the values of [(c1) / (c2)], the viscosity of the resin composition (25 ° C.), the average particle diameter of the resin particles (dispersed particles), and the pH.

<Example 4>
According to the formulation shown in Table 1 below, polyol C433 g, isocyanate Y 386 g, dimethylol butanoic acid 63 g (426 mmol), film forming aid 150 g, and DOTDL 100 ppm were charged in a reaction vessel, and the same as in Example 1. A urethanization reaction was performed to obtain an isocyanate group-terminated prepolymer containing a carboxyl group, and 43 g of a neutralizing agent (TEA) was added thereto for neutralization treatment.
Next, an aqueous solution of an extender composed of 1907 g of water (dispersion medium) and 18 g (175 mmol) of diethylenetriamine was added to the neutralized isocyanate group-terminated prepolymer. By emulsifying and dispersing the polymer and performing a chain extension reaction, a resin composition (water-based resin composition of the present invention) having a solid content of 30% obtained by dispersing resin particles in water was obtained.
The obtained aqueous resin composition had a viscosity (25 ° C.) of 30 mPa · s, an average particle size of the resin particles of 25 nm, and a pH of 8.5.
In this example, the use ratio (c1) of dimethylolbutanoic acid to the total solid mass (900 g) is 0.47 (= 426/900) mmol / g.
Moreover, the ratio (c2) of the imino group contained in the diethylenetriamine with respect to the total solid mass is 0.19 (= 175/900) mmol / g.
The ratio [(c1) / (c2)] is 2.5.

<Comparative Examples 1-3>
In accordance with the formulation shown in Table 1 below, polyol, isocyanate X, dimethylolpropionic acid, acetone, and DOTDL are charged into a reaction vessel, and a urethanization reaction is carried out in the same manner as in Example 1 to contain a carboxyl group. An isocyanate group-terminated prepolymer was obtained, and neutralized by adding a neutralizing agent (TEA).
Next, an aqueous solution of an extender is added to an acetone solution of an isocyanate group-terminated prepolymer that has been subjected to neutralization treatment, and the prepolymer is emulsified and dispersed and subjected to a chain extension reaction in the same manner as in Example 1. Acetone was removed by evaporation to obtain a resin composition in which resin particles were dispersed in water (an aqueous resin composition for comparison).
About each of the obtained water-based resin composition, the ratio (c2) of the imino group contained in the used diethylenetriamine with respect to the total mass of dimethylolpropionic acid with respect to the total mass of the solid content (c1), the ratio of the two Table 1 shows the values of [(c1) / (c2)], the viscosity of the resin composition (25 ° C.), the average particle diameter of the resin particles (dispersed particles), and the pH.

<Comparative example 4>
In accordance with the formulation shown in Table 1 below, 370 g of polyol C, 129 g of isocyanate X, 27 g (182 mmol) of dimethylolbutanoic acid, 180 g of film forming aid, and 100 ppm of DOTDL were charged in a reaction vessel, and the same as in Example 1. A urethanization reaction was performed to obtain an isocyanate group-terminated prepolymer containing a carboxyl group, and a neutralizing treatment was performed by adding 18 g of a neutralizing agent (TEA) thereto.
Next, an aqueous solution of an extender composed of 1168 g of water (dispersion medium) and 13 g of ethylenediamine is added to the neutralized isocyanate group-terminated prepolymer, and the prepolymer is emulsified and dispersed in the same manner as in Example 1. And a chain extension reaction to obtain a resin composition in which resin particles are dispersed in water (an aqueous resin composition for comparison).
The obtained aqueous resin composition had a viscosity (25 ° C.) of 70 mPa · s, an average particle size of the resin particles of 60 nm, and a pH of 9.0.
In this comparative example, the use ratio (c1) of dimethylolbutanoic acid to the total solid mass (539 g) is 0.34 (= 182/539) mmol / g.

* 1) Polyol A: A polycarbonate polyol having a number average molecular weight of 1,000 obtained from 1,6-hexanediol (HG) and diethyl carbonate (DEC).
* 2) Polyol B: Polycarbonate polyol having a number average molecular weight of 2,000 obtained from 1,6-hexanediol (HG) and diethyl carbonate (DEC).
* 3) Polyol C: Polyester polyol having a number average molecular weight of 2,000 obtained from neopentyl glycol (NPG), ethylene glycol (EG), isophthalic acid (IPhA), and adipic acid (AA).
* 4) Polyol D: Polycarbonate polyol having a number average molecular weight of 1,500 obtained from 3-methyl-1,5-pentanediol (MPD) and diethyl carbonate (DEC).
* 5) Isocyanate X: Isophorone diisocyanate (IPDI)
* 6) Isocyanate Y: Modified isopropyl alcohol HDI allophanate.
* 7) DMPA: dimethylolpropionic acid (molecular weight = 134)
* 8) DMBA: dimethylolbutanoic acid (molecular weight = 148)
* 9) Film forming aid: Dipropylene glycol dimethyl ether * 10) Neutralizing agent (TEA): Triethylamine * 11) DETA: Diethylenetriamine [molecular weight = 103, containing one imino group (—NH—) in the molecule ]
* 12) EDA: Ethylenediamine * 13) IPDA: Isophoronediamine

<Formation of cured coating film>
Each of the aqueous resin compositions obtained in Examples 1 to 4 and Comparative Examples 1 to 4 was applied to the surface of an aluminum plate (base material) with a bar coater, dried at 80 ° C. for 5 minutes, and a film thickness of 20 to 40 μm. The coating film thus formed was irradiated with light from a mercury lamp. The light irradiation conditions are as follows.

(Light irradiation conditions)
UV test device: “UVC-02528S1AKJ01” (USHIO INC.)
・ Lamp: High-pressure mercury lamp with an emission length of 250 mm (without N ₂ and O ₃ filters)
・ Line speed: 300cm / min
・ Irradiation amount: 950P · mW / cm ² × 10 pass

<Evaluation of solvent resistance>
For each of the coating films formed on the surface of the aluminum plate as described above, a MEK rubbing test before and after light irradiation (rubbing the coating film with a cotton swab impregnated with MEK and measuring the number of times until the coating film is peeled off) is performed. By performing, the solvent resistance of the (cured) coating film and the effect of improving the solvent resistance by light irradiation (rank increase) were evaluated. The evaluation criteria are as follows. The results are shown in Table 2 below.

(Evaluation criteria)
“A”: Does not peel even 16 times or more.
“B”: peeled off 11 to 15 times.
“C”: peeled off 6 to 10 times.
“D”: peeled 2 to 5 times.
“E”: peeled once.

<Evaluation of water resistance>
For each of the coating films formed on the surface of the aluminum plate as described above, by performing the following test before and after light irradiation, the water resistance of the (cured) coating film and the water resistance improvement effect by light irradiation (rank) Increase).

(Test method)
A drop of purified water is dropped onto the coating film with a dropper, and a cover glass is placed on the coated film. After standing at room temperature (15-25 ° C.) or 50 ° C. for 2 hours, the appearance of the film is observed. Based on the criteria of the evaluation. The results are shown in Table 2 below.

(Evaluation criteria)
“A”: No change was observed even at 50 ° C.
“B”: Trace of whitening was observed at 50 ° C.
“C”: Whitening was observed at 50 ° C.
“D”: Whitening was observed at room temperature.
“E”: dissolved at room temperature.

The aqueous resin composition of the present invention can be used in all fields in which coating treatment is performed, such as paints, adhesives, printing inks, fiber restraints, and inorganic binders.

Claims (3)

In an aqueous resin composition in which resin particles are dispersed in an aqueous medium and cured by ultraviolet rays and / or electron beams,
The resin particles are obtained by dispersing an isocyanate group-terminated prepolymer obtained by reacting an isocyanate, a long-chain polyol, and a dimethylol fatty acid and then neutralizing it in an aqueous medium, and extending the reaction with a polyalkylene polyamine. Resin particles synthesized by
The content ratio (C1) of the carboxyl group and / or carboxylate group derived from the dimethylol fatty acid is 0.40 mmol / g or more,
The content (C2) of the structure (—N═) derived from the imino group (—NH—) of the polyalkylene polyamine is 0.02 mmol / g or more,
A water-based resin composition, wherein the content ratio (C1) / (C2) is a resin particle of 1 to 20. In the method of manufacturing the aqueous resin composition according to claim 1,
A step of obtaining an isocyanate group-terminated prepolymer by performing a neutralization treatment after reacting an isocyanate, a long-chain polyol, and a dimethylol fatty acid in a solvent or in the absence of a solvent;
A step of dispersing the isocyanate group-terminated prepolymer in an aqueous medium and an extension reaction with a polyalkylene polyamine,
The ratio (c1) of the amount of dimethylol fatty acid used (number of millimoles) to the total amount of the isocyanate, long-chain polyol, dimethylol fatty acid and polyalkylenepolyamine used (mass) is 0.40 mmol / g or more. Yes,
The imino group ratio (c2) contained in the polyalkylene polyamine used is 0.02 mmol / g or more with respect to the total amount (mass) of the isocyanate, the long-chain polyol, the dimethylol fatty acid and the polyalkylene polyamine. And
The method for producing an aqueous resin composition, wherein the ratio (c1) / (c2) is 1 to 20. A method for forming a cured coating film, comprising irradiating the coating film formed of the aqueous resin composition according to claim 1 with ultraviolet rays and / or electron beams.