JP2014227501A - Aqueous urethane-modified (meth)acrylic resin dispersion and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method capable of stably manufacturing an aqueous urethane-modified (meth)acrylic resin dispersion and yielding an aqueous urethane-modified (meth)acrylic resin dispersion having a favorable liquid stability.SOLUTION: A polyol (a) and an acid anhydride (b) are reacted within a monomer composition (A) including a (meth)acrylic monomer for generating a carboxyl group-containing polyol (B) and for obtaining a liquid mixture (I) including the monomer composition (A) and polyol (B). The polyol (B), a polyisocyanate (c), and a compound (d) including glycidyl groups and polymerizable unsaturated groups are reacted within the liquid mixture (I) for generating an urethane prepolymer (C2) including carboxyl groups and polymerizable unsaturated groups and for obtaining a liquid mixture (II) including the monomer composition (A) and urethane prepolymer (C2). After the liquid mixture (II) has been emulsified by adding thereto a neutralizer and water and then polymerized, an aqueous urethane-modified (meth)acrylic resin dispersion is obtained.

Description

  The present invention relates to an aqueous urethane-modified (meth) acrylic resin dispersion and a method for producing the same.

Conventionally, (meth) acrylic resins and urethane resins have been used as aqueous resins for coating agents, paints, and inks.
(Meth) acrylic resin is excellent in weather resistance, gloss, alkali resistance, etc., but it is difficult to achieve both hardness and softness when formed into a coating film, such as flex resistance, impact resistance, wear resistance, etc. Was insufficient. On the other hand, the urethane resin is excellent in mechanical properties, adhesion, abrasion resistance, flexibility and the like, but has poor weather resistance, alkali resistance, heat resistance and the like, and is expensive.

In Patent Document 1, for urethane resins, organic diisocyanate compounds, high molecular weight diol compounds, alkene diols, and the like are used for the purpose of improving laminate strength, water resistance, hot water resistance, etc. when used as a resin binder for aqueous laminate adhesives. A method for producing a urethane resin having a molecular weight of 4,000 to 200,000 by reacting a chain extender and a reaction terminator and having at least one hydrazine residue and a radical polymerizable double bond in the molecule. It is disclosed.
However, as long as it is a urethane resin, the improvement effect by the method described in Patent Document 1 is limited.

In order to compensate for the disadvantages of both resins, a method of combining a (meth) acrylic resin and a urethane resin has been proposed.
For example, Patent Document 2 discloses that in a (meth) acrylic monomer having no active hydrogen, a polyisocyanate, a compound containing two or more functional groups selected from a hydroxyl group and an amino group, and having an acidic functional group, an acidic A urethane prepolymer having a polymerizable unsaturated group and an acidic functional group is produced by reacting a polyol having no functional group with a compound having a glycidyl group and a polymerizable unsaturated group in the molecule. After mixing, diluting with water and emulsifying, the urethane prepolymer is subjected to a chain extension reaction and a radical polymerization reaction of the (meth) acrylic monomer and the urethane prepolymer, whereby an acrylic resin and a urethane resin are obtained. A method for producing an aqueous urethane-modified (meth) acrylic resin dispersion in which is bonded is disclosed.

Japanese Unexamined Patent Publication No. 7-196664 JP2011-173955 A

According to the method described in Patent Document 2, an aqueous urethane-modified (meth) acrylic resin dispersion excellent in liquid stability such as alcohol shock resistance, durability against freeze-thaw cycles, and thermal stability is obtained. Yes.
However, according to the study of the present inventor, the method described in Patent Document 2 still has room for improvement in liquid stability. There is also room for improvement in manufacturing stability. For example, in the method described in Patent Document 2, it is difficult for a compound having an acidic functional group or the like to be dissolved in a (meth) acrylic monomer, and as the urethanization reaction proceeds, generation of precipitates occurs, and the urethane prepolymer is produced. Stability is likely to decrease.

  The present invention has been made in view of the above circumstances, and can stably produce an aqueous urethane-modified (meth) acrylic resin dispersion, and the liquid stability of the resulting aqueous urethane-modified (meth) acrylic resin dispersion is also good. An object of the present invention is to provide a simple production method and an aqueous urethane-modified (meth) acrylic resin dispersion obtained by the production method.

The first aspect of the present invention is a method for producing an aqueous urethane-modified (meth) acrylic resin dispersion, comprising the following step 1, step 2 and step 3.
Step 1: In the monomer composition (A) containing a (meth) acrylic monomer, the polyol (a) and the acid anhydride (b) are reacted to produce a polyol (B) having a carboxy group, The process of obtaining the liquid mixture (I) containing the said monomer composition (A) and the said polyol (B).
Step 2: In the mixed liquid (I) obtained in Step 1, the polyol (B), the polyisocyanate (c), and the compound (d) having a glycidyl group and a polymerizable unsaturated group are reacted. The process which produces | generates the urethane prepolymer (C2) which has a carboxy group and a polymerizable unsaturated group, and obtains the liquid mixture (II) containing the said monomer composition (A) and the said urethane prepolymer (C2).
Step 3: A step of adding a neutralizing agent and water to the mixed liquid (II) obtained in Step 2 to emulsify, and then performing a polymerization reaction to obtain an aqueous urethane-modified (meth) acrylic resin dispersion.

The second aspect of the present invention is a method for producing an aqueous urethane-modified (meth) acrylic resin dispersion, comprising the following step 1, step 4 and step 5.
Step 1: In the monomer composition (A) containing a (meth) acrylic monomer, the polyol (a) and the acid anhydride (b) are reacted to produce a polyol (B) having a carboxy group, The process of obtaining the liquid mixture (I) containing the said monomer composition (A) and the said polyol (B).
Step 4: In the mixed liquid (I) obtained in Step 1, the polyol (B) and the polyisocyanate (c) are reacted to produce a urethane prepolymer (C4) having a carboxy group, The process of obtaining liquid mixture (IV) containing a monomer composition (A) and the said urethane prepolymer (C4).
Step 5: The mixture (IV) obtained in Step 4 is emulsified by adding a neutralizing agent and water, and then the compound (d) having a glycidyl group and a polymerizable unsaturated group and the urethane prepolymer (C4). ) And a polymerization reaction to obtain an aqueous urethane-modified (meth) acrylic resin dispersion.

  The third aspect of the present invention is an aqueous urethane-modified (meth) acrylic resin dispersion obtained by the production method of the first aspect or the second aspect.

  According to the present invention, a water-based urethane-modified (meth) acrylic resin dispersion can be stably produced, and the resulting water-based urethane-modified (meth) acrylic resin dispersion has good liquid stability and is obtained by the production method. An aqueous urethane-modified (meth) acrylic resin dispersion can be provided.

Hereinafter, the present invention will be described in detail.
In this specification, (meth) acrylate indicates both acrylate and methacrylate, and (meth) acrylic acid indicates both acrylic acid and methacrylic acid.

[Production Method of First Aspect]
The production method of the first aspect of the present invention (hereinafter also referred to as production method (1)) includes the following step 1, step 2 and step 3.
Step 1: In the monomer composition (A) containing the (meth) acrylic monomer, the polyol (a) (hereinafter referred to as “component (a)”) and the acid anhydride (b) (hereinafter referred to as “(b ) Component ”) to produce a polyol (B) having a carboxy group to obtain a mixed liquid (I) containing the monomer composition (A) and the polyol (B).
Step 2: In the mixed liquid (I) obtained in Step 1, the polyol (B), polyisocyanate (c) (hereinafter referred to as “component (c)”), glycidyl group and polymerizable unsaturated And reacting with a group-containing compound (d) (hereinafter referred to as “component (d)”) to produce a urethane prepolymer (C2) having a carboxy group and a polymerizable unsaturated group, and the monomer composition (A And a liquid mixture (II) containing the urethane prepolymer (C2).
Step 3: The mixture (II) obtained in Step 2 was added with a neutralizing agent and water to emulsify, and then subjected to a polymerization reaction to form an aqueous urethane-modified (meth) acrylic resin dispersion (hereinafter simply referred to as “aqueous”). Step of obtaining a resin dispersion ”.

In the production method (1), in the monomer composition (A) containing a (meth) acrylic monomer, first, a polyol (B) having a carboxy group is produced, and then a carboxy group and a polymerizable unsaturated group are produced. A urethane prepolymer (C2) is produced, and then a neutralizing agent and water are added to neutralize and emulsify carboxy groups, and then a polymerization reaction is performed. As a result, the monomer constituting the monomer composition (A) and the urethane prepolymer (C2) are polymerized to obtain an aqueous resin dispersion in which the urethane-modified (meth) acrylic resin in which the acrylic resin and the urethane resin are bonded is dispersed in water. It is done.
Hereinafter, the monomer composition (A) and the components (a) to (d) and the steps 1 to 3 will be described in detail.

<Monomer composition (A)>
The monomer composition (A) contains a (meth) acrylic monomer.
The (meth) acrylic monomer is a compound having a (meth) acryloyl group (CH ₂ ═C (R) —C (═O) —, where R represents a hydrogen atom or a methyl group). The (meth) acrylic monomer may have one (meth) acryloyl group or two or more.

  Examples of (meth) acrylic monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, and 2-ethylhexyl. (Meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, lauryl (meth) acrylate, (meth) acrylate having an alkyl group having 12 to 13 carbon atoms, tridecyl (meth) acrylate, stearyl (meth) acrylate, Methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) methacrylate, methoxy ester (Meth) acrylic acid alkyl esters such as xylethyl (meth) acrylate, ethoxyethoxyethyl ((meth) acrylate, propoxyethoxyethyl (meth) acrylate, butoxyethoxyethyl (meth) acrylate); (meth) acrylamide, N-butoxymethyl ( (Meth) acrylic monomers having amide groups such as (meth) acrylamide, N-methylacrylamide, N, N-dimethylacrylamide, N-isopropyl (meth) acrylamide; N, N-dimethylaminoethyl (meth) acrylate, (Meth) acrylic acid ester having a tertiary amino group such as N, N-diethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl methacrylate; cyclopentyl (meth) acrylate, cyclohexyl (medium ) Alicyclic (meth) acrylic esters such as acrylate and isobornyl (meth) acrylate; Aromatic (meth) acrylic monomers such as benzyl methacrylate and phenyl methacrylate; γ-methacryloyloxypropyltrimethoxysilane and the like Silicon-containing acrylic monomers; fluorinated acrylic monomers such as octafluoropentyl (meth) acrylate and perfluorocyclohexyl (meth) acrylate; (meth) acrylic monomers having blocked isocyanate groups; 2 -(Meth) acrylic acid ester having a hydroxyl group such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate; (meth) acrylic having a carboxy group such as (meth) acrylic acid Monomers; etc. And the like. A (meth) acrylic monomer having two (meth) acryloyl groups (for example, polyethylene glycol di (meth) acrylate) may be used.

The (meth) acrylic monomer in the monomer composition (A) may be one type or two or more types.
When using the resulting aqueous resin dispersion in coating agents, paints, inks, etc., in terms of the balance of paintability to the object to be coated, adhesion of the formed film to the object to be coated, and film properties The monomer composition (A) preferably contains two or more (meth) acrylic monomers.

Among the above, the (meth) acrylic monomer is preferably a (meth) acrylic monomer having no active hydrogen in the molecule (hereinafter also referred to as “component (e)”).
Active hydrogen means highly reactive hydrogen bonded to an atom having a large electronegativity such as oxygen or nitrogen. For example, hydrogen contained in a carboxy group, a hydroxyl group, a methylol group, a silanol group, a primary amino group, a secondary amino group, etc. is an active hydrogen.
As the component (e), among the above (meth) acrylic monomers, (meth) acrylic acid alkyl esters and (meth) acrylic acid esters having a tertiary amino group are preferable.
Examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl ( More preferred are (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, lauryl (meth) acrylate, (meth) acrylate having 12 or 13 carbon atoms, tridecyl methacrylate, stearyl (meth) acrylate, and the like.
Examples of (meth) acrylic acid ester having a tertiary amino group include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and the like. Is more preferable.

The monomer composition (A) may be composed of a (meth) acrylic monomer or may further contain a vinyl monomer other than the (meth) acrylic monomer.
A vinyl monomer is a compound having a polymerizable double bond. One or two or more polymerizable double bonds may be included in the vinyl monomer.
Examples of vinyl monomers other than (meth) acrylic monomers include, for example, nitrogen-containing unsaturated monomers such as N-vinylpyrrolidone, N-vinylimidazole and N-vinylcarbazole; styrene such as styrene and α-methylstyrene Examples thereof include silicon-based unsaturated monomers such as vinyltriethoxysilane; unsaturated monomers having a carboxy group such as itaconic acid and crotonic acid. Moreover, you may use the unsaturated monomer (for example, divinylbenzene etc.) which has two polymerizable double bonds as vinylic monomers other than a (meth) acrylic-type monomer.

  The content of the (meth) acrylic monomer in the monomer composition (A) is preferably 60 to 100% by mass with respect to the total amount (100% by mass) of all monomers constituting the monomer composition (A). -100 mass% is more preferable. When the content of the (meth) acrylic monomer in the monomer composition (A) is not less than the lower limit (60% by mass) of the above range, the components (a) to (c) described later are well dissolved and urethanized. Reaction can be performed stably and it is easy to make a urethane prepolymer high molecular weight. When the urethane prepolymer has a high molecular weight, the solvent resistance and water resistance of the coating film formed from the resulting aqueous resin dispersion are improved.

The monomer composition (A) is also referred to as a monomer having active hydrogen in the molecule (hereinafter referred to as “component (f)”) as a (meth) acrylic monomer or a vinyl monomer other than the (meth) acrylic monomer. ) May be included.
However, the ratio of the (e) component and the (f) component in the monomer composition (A) is a mass ratio, and preferably within the range of (e) component: (f) component = 60: 40 to 100: 0. (E) component: (f) component = more preferably within the range of 80:20 to 100: 0. When the ratio of the component (e) is not less than the lower limit of the above range (component (e): component (f) = 60: 40), the urethanization reaction proceeds efficiently, and the urethane prepolymer has a high molecular weight. easy. When the urethane prepolymer has a high molecular weight, the solvent resistance and water resistance of the coating film formed from the resulting aqueous resin dispersion are improved.

  As the monomer constituting the monomer composition (A), it is desirable to select a monomer that dissolves the components (a) to (c) described later well. Any monomer that dissolves as the post-reaction progresses may be used.

<(A) component>
The component (a) is a polyol. A polyol is a compound having two or more hydroxyl groups in the molecule.
Examples of the component (a) include a low molecular weight polyol having a molecular weight of 50 to 500 and a high molecular weight polyol having a molecular weight of 500 to 5000.
Examples of the low molecular weight polyol include divalent alcohols such as ethylene glycol, diethylene glycol, trimethylene glycol, triethylene glycol, propylene glycol, butylene glycol, hexamethylene glycol, and neopentyl glycol.

Examples of the high molecular weight polyol include polyether polyol, polyester polyol, acrylic polyol, and epoxy polyol.
Examples of the polyether polyol include polyethylene glycol, polyoxypropylene glycol, poly (ethylene / propylene) glycol, and polytetramethylene glycol.
Examples of the polyester polyol include polyester composed of a polycondensate of a diol and a dibasic acid. Examples of the diol include ethylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and 3-methyl 1,5-pentanediol. Examples of the dibasic acid include adipic acid, azelaic acid, sebacic acid, isophthalic acid, terephthalic acid and the like. In addition to the above-described polyester, for example, lactone ring-opening polymer polyols such as polycaprolactone and poly β-methyl-δ-valerolactone, polycarbonate diol, and the like may be used.
Examples of the acrylic polyol include a copolymer of a monomer having a hydroxyl group. Examples of the hydroxyl group-containing monomer include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl acrylate, dihydroxy acrylate and the like.
Examples of the epoxy polyol include an amine-modified epoxy resin.
Further, in addition to the above-described polyol, for example, polybutadiene diol, castor oil, or the like may be used.

These (a) components can be used individually by 1 type or in mixture of 2 or more types.
In order to balance the adhesion to the object to be coated, the paintability, or the physical properties of the coating film, it is preferable to use a mixture of two or more different chemical structures as the component (a).
In addition, when two or more types of component (a) are used in combination, the adhesiveness to the object to be coated, paintability, or physical properties of the coating film can be balanced by appropriately selecting the molecular weight of each component (a). be able to.

In the present invention, from the viewpoint of addition reactivity with the component (b) and high molecular weight of the urethane prepolymer, the component (a) is a dihydric alcohol and a polyol having three or more hydroxyl groups in the molecule. It is preferable to include.
As the dihydric alcohol, high molecular weight polyether diol, polyester diol, polycarbonate diol and the like are preferable.
The polyol having three or more hydroxyl groups in the molecule is preferably a trivalent or higher alcohol.

Examples of trihydric or higher alcohols include trimethylolpropane, trimethylolethane, trimethylolbenzene, hexanetriol, pentanetriol, heptanetriol, octanetriol, nonanetriol, decanetriol, benzenetriol, ethylene oxide / Trivalent alcohols such as propylene oxide adducts, glycerin and polyglycerin; tetravalent alcohols such as pentaerythritol, ditrimethylolpropane, diglycerin and pentaerythritol ethylene oxide / propylene oxide adducts; pentavalent alcohols such as xylitol Hexavalent such as dipentaerythritol, sorbitol, mannitol, ethylene oxide / propylene oxide adduct of sorbitol, etc. Such as alcohol and the like.
Here, “ethylene oxide / propylene oxide adduct” means a product in which only one of ethylene oxide or propylene oxide is added, or a product in which both are added.

Examples of trihydric or higher alcohols include trimethylolpropane or its ethylene oxide / propylene oxide adduct, pentaerythritol ethylene oxide / propylene oxide adduct, and sorbitol ethylene oxide from the viewpoint of solubility in the monomer composition (A). / Propylene oxide adduct is preferred.
Further, from the viewpoint of addition reactivity with the component (b), a low molecular weight alcohol having a molecular weight of 50 to 500 is preferable, and trimethylolpropane is particularly preferable.

<(B) component>
The component (b) is an acid anhydride.
Examples of the component (b) include succinic anhydride, octyl succinic anhydride, octenyl succinic anhydride, dodecyl succinic anhydride, dodecenyl succinic anhydride, tetradecyl succinic anhydride, tetradecenyl succinic anhydride, octadecyl succinic anhydride, octadecenyl anhydride Aliphatic acid anhydrides such as succinic acid, polyadipic acid anhydride, polyazeline acid anhydride, polysebacic acid anhydride, poly (ethyloctadecanedioic acid) anhydride, poly (phenylhexadecanedioic acid) anhydride; tetrahydrophthalic anhydride Hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, 3,6-endomethylenetetrahydrophthalic anhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene 1,2-dicarboxylic anhydride Aliphatic acid anhydrides such as: phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bis (anhydrotrimellitate), glycerol tristrimellitic anhydride, glycerin And aromatic acid anhydrides such as bisahydrohydrotrimellitate monoacetate; halogen acid anhydrides such as tetrabromophthalic anhydride; and the like.

These (b) components can be used individually by 1 type or in mixture of 2 or more types.
As the component (b), succinic anhydride, methylhexahydrophthalic anhydride, and glycerin bisanhydro trimellitate monoacetate are preferable from the viewpoint of solubility in the monomer composition (A). In view of reactivity, succinic anhydride is particularly preferable.

<(C) component>
(C) A component is polyisocyanate. Polyisocyanate is a compound having two or more isocyanate groups in the molecule.
Examples of the component (c) include aliphatic polyisocyanates, aromatic polyisocyanates, alicyclic polyisocyanates and derivatives thereof. Specifically, xylylene diisocyanate, polyphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, isophorone diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, naphthalene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, dicyclohexylmethane diisocyanate And diisocyanates such as these and polymers thereof.
Further, as the component (c), for example, a condensate of a polyisocyanate compound such as the above 4,4′-diphenylmethane diisocyanate and a compound having an allophanate bond, an isocyanurate bond, a carbodiimide bond, or the like may be used.

These (c) components can be used individually by 1 type or in mixture of 2 or more types.
As component (c), as will be described in detail later, the reactivity between isocyanate groups and water when the urethane prepolymer produced in the monomer composition (A) is dispersed in water, and the resulting aqueous resin dispersion From the viewpoint of weather resistance, aliphatic polyisocyanates and alicyclic polyisocyanates are preferred. Further, from the viewpoint of compatibility with the monomer composition (A), alicyclic polyisocyanates are preferable, and isophorone diisocyanate is particularly preferable.

<(D) component>
The component (d) is a compound having a glycidyl group and a polymerizable unsaturated group.
Examples of the component (d) include glycidyl (meth) acrylate, glycidyloxyethyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, allyl glycidyl ether, and the like.
These (d) components can be used individually by 1 type or in mixture of 2 or more types.
As the component (d), glycidyl (meth) acrylate is preferable from the viewpoint of addition reactivity with the carboxy group in the urethane prepolymer or the carboxy group in the polyol (B).

<< Process 1 >>
In step 1, the component (a) and the component (b) are reacted (addition reaction) in the monomer composition (A). Thereby, the polyol (B) which has a carboxy group produces | generates, and the liquid mixture (I) containing a monomer composition (A) and a polyol (B) is obtained.

In step 1, the component (a) and the component (b) are mixed such that the molar ratio of the hydroxyl group in the component (a) to the acid anhydride group in the component (b) is hydroxyl group: acid anhydride group = 4: 1. It is preferable to mix and react so as to be in the range of ˜2: 1. The molar ratio is more preferably in the range of hydroxyl group: acid anhydride group = 3.5: 1 to 2.5: 1.
When the (a) component and the (b) component are reacted within the range of hydroxyl group: acid anhydride group = 4: 1 to 2: 1, the subsequent production of the urethane prepolymer (step 2) and the subsequent aqueous resin The production of the dispersion (Step 3) can be performed stably.
In addition, when a polyol having a small number of hydroxyl groups in the molecule is formed as the polyol (B) during the addition reaction, the polyol acts as a terminal blocking agent for the urethanization reaction, and the urethane prepolymer can be easily reduced in molecular weight. On the other hand, when the polyol (B) having a large number of hydroxyl groups in the molecule is produced, the polyol acts as a crosslinking reaction point of the urethanization reaction (reaction with the component (c) in step 2), High viscosity and gelation are likely to occur, and the production stability is likely to decrease.
When the component (a) is reacted so that the compounding ratio of the hydroxyl group is not less than the lower limit of the above range (hydroxyl group: acid anhydride group = 2: 1), the generation of the polyol (B) acting as a terminal blocking agent is suppressed. It is easy to increase the molecular weight of the urethane prepolymer. On the other hand, when the component (a) is reacted so that the compounding ratio of the hydroxyl group is not more than the upper limit of the above range (hydroxyl group: acid anhydride group = 2: 1), a polyol (B) that acts as a crosslinking reaction point is generated. Can be suppressed, and the urethanization reaction can be performed stably.

  In Step 1, the reaction between the component (a) and the component (b) is usually preferably carried out under conditions of a reaction temperature (temperature in the reaction system) of 50 to 100 ° C. and a reaction time of 1 to 10 hours. If the addition reaction is carried out under the conditions within this range, the polyol (B) can be produced efficiently and the unreacted component (b) can be reduced. When the amount of the unreacted component (b) decreases, it is easy to improve the solvent resistance and water resistance of the coating film formed from the aqueous resin dispersion obtained. Further, it is easy to produce a urethane prepolymer having an acid value as set, and the subsequent emulsification and polymerization reaction in Step 3 can be performed stably.

The reaction between the component (a) and the component (b) proceeds even if there is no catalyst in the reaction system, but can be more easily proceeded if a catalyst is used.
Examples of the catalyst include sodium hydroxide, potassium hydroxide, ammonia, triethylamine, dimethylbenzylamine, dimethylethanolamine, zirconium octoate, zinc naphthenate and the like.

<< Process 2 >>
In step 2, polyol (B), component (c), and component (d) are reacted in the mixed liquid (I) obtained in step 1. Thereby, the urethane prepolymer (C2) which has a carboxy group derived from the polyol (B) and a polymerizable unsaturated group derived from the component (d) is generated.
Step 2 is performed continuously after Step 1, and the reaction proceeds in the monomer composition (A). Therefore, the mixture (II) containing the monomer composition (A) and the urethane prepolymer (C2) is obtained by the above reaction.

In Step 2, the acid value of the urethane prepolymer (C2) obtained from the component (c) and the component (d) with respect to the polyol (B) is in the range of 35 to 150 mgKOH / g in terms of solid content. It is preferable to mix and react. The acid value of the urethane prepolymer (C2) is more preferably in the range of 60 to 125 mgKOH / g.
When the acid value of the urethane prepolymer (C2) is within the above range, the production of the urethane prepolymer (C2) and the subsequent production of the aqueous resin dispersion can be performed more stably.
When the acid value (C2) of the urethane prepolymer is not less than the lower limit (35 mgKOH / g) of the above range, the dispersion stability of the monomer composition (A) at the time of emulsification in Step 3 is improved. The occurrence of cullet during radical polymerization reaction is suppressed, and the production stability is improved. On the other hand, when the acid value of the urethane prepolymer (C2) is not more than the upper limit (150 mgKOH / g) of the above range, the solvent resistance and water resistance of the coating film formed from the obtained aqueous resin dispersion are improved.
The acid value of the urethane prepolymer (C2) is a theoretical value (theoretical acid value) determined by the formula (iii) described later.

Reaction of a polyol (B), (c) component, and (d) component can be performed by the following method (2-1) or (2-2), for example.
Method (2-1): In the mixed liquid (I), the reaction between the polyol (B) and the component (c) (urethanization reaction) is performed, and then the reaction between the reaction product and the component (d) ( (Addition reaction).
Method (2-2): Reaction (addition reaction) between polyol (B) and component (d) in mixture (I) and then reaction between the reaction product and component (c) (urethane) The method of performing a chemical reaction.
Among these, from the point that the liquid stability of the aqueous resin dispersion obtained is improved and the water resistance and solvent resistance of the coating film obtained from the aqueous resin dispersion are improved, the method (2-1) is preferable.

In the urethanization reaction of the method (2-1), the polyol (B) and the component (c) are mixed such that the molar ratio of the hydroxyl group in the polyol (B) to the isocyanate group in the component (c) is hydroxyl group: isocyanate group. = It is preferable to mix | blend and react so that it may become in the range of 0.5: 1-2: 1. The molar ratio is more preferably in the range of hydroxyl group: isocyanate group = 1: 1 to 2: 1.
Hydroxyl group: When the polyol (B) and the component (c) are reacted so that the isocyanate group is within the above range, a urethane prepolymer having an isocyanate group at the terminal can be easily produced. Such a urethane prepolymer is likely to have a high molecular weight in a chain extension reaction that is optionally performed in Step 3 described later.

  The urethanization reaction is usually preferably performed under the conditions of a reaction temperature (temperature in the reaction system) of 50 to 100 ° C. and a reaction time of 1 to 10 hours. If the urethanization reaction is performed under the conditions within this range, the reaction between the polyol (B) and the component (c) can be performed efficiently, and the unreacted polyol (B) and the component (c) can be reduced. . When unreacted polyol (B) and (c) component reduce, there exists a tendency for the solvent resistance and water resistance of the coating film formed from the aqueous resin dispersion obtained to improve.

  In the urethanization reaction, a polymerization inhibitor such as p-methoxyphenol is added to the monomer composition (A) in the presence of air in order to prevent the monomer composition (A) from being polymerized by heat during the reaction. You may keep it.

In the urethanization reaction, when the progress of the reaction is slow, the catalyst may be added in an amount of about 0.1 to 1.0 part by mass with respect to 100 parts by mass of the urethane prepolymer.
Examples of the catalyst include organotin compounds such as dibutyltin dilaurate, dibutyltin dioctoate, stannous octoate; and tertiary amine compounds such as triethylamine and triethylenediamine.

  In general, the addition reaction in the method (2-1) is preferably performed under the conditions of a reaction temperature (temperature in the reaction system) of 50 to 100 ° C. and a reaction time of 1 to 10 hours. If the addition reaction is carried out under the conditions within this range, a large amount of polymerizable unsaturated groups can be introduced into the urethane prepolymer (C2). Therefore, the amount of bonds between the urethane resin and the acrylic resin increases, and the aqueous resin dispersion It is easy to improve the liquid stability.

  The addition reaction and urethanization reaction in the method (2-2) can be carried out in the same manner as the addition reaction and urethanization reaction in the method (2-1), respectively.

1000-15000 are preferable and, as for the number average molecular weight of a urethane prepolymer (C2), 2000-10000 are more preferable. When the number average molecular weight of the urethane prepolymer (C2) is 1000 or more, it is easy to improve the solvent resistance and water resistance of the coating film obtained from the aqueous resin dispersion. On the other hand, when the number average molecular weight of the urethane prepolymer (C2) is 15000 or less, the urethanization reaction during the production of the urethane prepolymer (C2) can be performed stably.
The number average molecular weight of the urethane prepolymer (C2) is a value in terms of polystyrene measured by gel permeation chromatography (GPC). GPC can be performed using a commercially available GPC device (for example, manufactured by Tosoh Corporation).
The number average molecular weight of the urethane prepolymer (C2) can be adjusted by changing the molar ratio of the hydroxyl group to the isocyanate group in the urethanization reaction performed by the method (2-1) or the method (2-2).

In the mixed liquid (II), the mass ratio of the urethane prepolymer (C2) to the monomer composition (A) is within the range of urethane prepolymer (C2): monomer composition (A) = 20: 80 to 90:10. The urethane prepolymer (C2): monomer composition (A) is more preferably within the range of 30:70 to 70:30.
If each component is blended so that the mass ratio of the urethane prepolymer (C2) and the monomer composition (A) is within the above range, Step 2 and Step 3 can be performed stably, and the resulting aqueous resin dispersion The liquid stability is good. Moreover, the solvent resistance and water resistance of the coating film formed from the aqueous resin dispersion are also good.
In addition, the monomer composition at the time of the emulsification process in the process 3 that the ratio of a urethane prepolymer (C2) is more than the lower limit (Urethane prepolymer (C2): monomer composition (A) = 20: 80) of the said range. The dispersion stability of the product (A) is improved, so that the occurrence of cullet during the radical polymerization reaction is suppressed, and the production stability is improved. On the other hand, if the ratio of the urethane prepolymer (C2) is not more than the upper limit of the above range (urethane prepolymer (C2): monomer composition (A) = 90: 10), the system during the urethanization reaction in step 2 The inside viscosity does not become too high, and the urethanization reaction can be performed stably. Moreover, also in the following process 3, the viscosity increase by neutralization is suppressed and the emulsification process can be performed stably.

<< Process 3 >>
In step 3, first, a neutralizer and water are added to the mixed liquid (II) obtained in step 2 to emulsify (neutralization / emulsification step). Thereby, while the carboxy group of urethane prepolymer (C2) in liquid mixture (II) is neutralized, the dispersion liquid which liquid mixture (II) disperse | distributed in water is obtained.
After the neutralization / emulsification step, a polymerization reaction is performed. As a result, the monomer and the urethane prepolymer (C2) constituting the monomer composition (A) undergo radical polymerization in the dispersion, and the urethane-modified (meth) acrylic resin in which the acrylic resin and the urethane resin are bonded is dispersed in water. An aqueous resin dispersion is obtained.
If necessary, a chain extension reaction of the neutralized urethane prepolymer (C2) may be performed after the neutralization / emulsification step, before the polymerization reaction, or simultaneously with the polymerization reaction.

(Neutralization / emulsification process)
The neutralization / emulsification step is, for example, a method in which a solution obtained by mixing a neutralizing agent and water is gradually added dropwise to the mixed solution (II) and emulsified, and the neutralizing agent is added to the mixed solution (II). It is possible to carry out by a method such as adding only water to neutralize, and then adding water to emulsify.
From the viewpoint of suppressing the heat of neutralization and further facilitating emulsification, a method of gradually adding and emulsifying a mixed solution (II) in which a neutralizer and water are mixed is preferable.

As the neutralizing agent, basic substances such as organic amines and inorganic bases can be used.
Examples of organic amines include methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, ethanolamine, propanolamine, diethanolamine, N-methyldiethanolamine, dimethylamine, diethylamine, triethylamine, N, N-dimethylethanolamine. 2-dimethylamino-2-methyl-1-propanol, 2-amino-2-methyl-1-propanol, morpholine and the like.
Examples of inorganic bases include lithium, potassium, sodium, sodium hydroxide, potassium hydroxide, and ammonia.
These neutralizing agents can be used singly or in combination of two or more.
Among these, organic amines and ammonia are preferable, and triethylamine and N, N-dimethylethanolamine are particularly preferable because they have volatility after being formed into a coating film.

  The addition amount of the neutralizing agent is preferably about 0.8 to 1.2 equivalents (80 to 120% in terms of neutralization rate) with respect to 1 equivalent of the carboxy group in the urethane prepolymer (C2). When the neutralization rate is 0.8 equivalents or more, the dispersion stability of the monomer composition (A) at the time of emulsification is improved, and therefore the occurrence of cullet at the time of radical polymerization reaction is suppressed, and the production stability is improved. . On the other hand, when the neutralization rate is 1.2 equivalents or less, the viscosity of the reaction system decreases and emulsification becomes easy. Moreover, since the quantity of the neutralizing agent which remains in the aqueous resin dispersion obtained becomes small, the solvent resistance and water resistance of the coating film formed are easy to improve.

If the urethane prepolymer (C2) has a high viscosity or the urethane prepolymer (C2) has a low acid value, it is difficult to emulsify only by adding a neutralizing agent. It can also be used in combination with a Japanese-style medicine.
As the emulsifier, it is preferable to use a reactive emulsifier described later in consideration of the water resistance and weather resistance of the dried coating film.

(Chain extension reaction)
The chain extension reaction of the neutralized urethane prepolymer (C2) can be carried out using water present in the reaction system (the dispersion obtained in the neutralization / emulsification step) as it is as a chain extender.
The chain extension reaction may be performed using a chain extender other than water. As the chain extender other than water, polyamines are preferable in that the urethane resin can be made higher in molecular weight. When polyamines are used, a urea bond is formed in the urethane resin, a polyurethane-urea resin is obtained, and the molecular weight of the urethane resin portion can be increased. In particular, since trifunctional or higher polyamines also act as a crosslinking agent, the solvent resistance of the coating film is further improved.
Examples of polyamines include aliphatic, alicyclic, aromatic diamines, and triamines such as ethylenediamine, propylenediamine, hexamethylenediamine, triethylenetetramine, isophoronediamine, piperazine, and diphenyldiamine.
A monoamine may be used in combination with the polyamines. When a monoamine is used in combination, the chain extension reaction is stopped, so the molecular weight of the urethane resin can be easily adjusted.

The reaction temperature and reaction time for carrying out the chain extension reaction can be appropriately set in consideration of the type of chain extender used or the reactivity between the chain extender and the isocyanate group.
When water is used as a chain extender, the chain extension reaction is preferably performed at a reaction temperature (temperature in the reaction system) of 70 ° C. or higher. When the reaction temperature is 70 ° C. or higher, the chain extension reaction via water tends to proceed.
The chain extension reaction using water as a chain extender can be performed simultaneously with radical polymerization with the monomer composition (A) described later.

When a chain extender other than water is used, in order to suppress the reaction between the isocyanate group in the urethane prepolymer (C2) and water, before the step of emulsifying these urethane prepolymers (C2), or At the same time, it is preferable to lower the temperature in the reaction system to 70 ° C. or lower (more preferably 50 ° C. or lower) and then add a chain extender to carry out a chain extension reaction. By lowering the temperature in the reaction system to 70 ° C. or lower, the reaction between water and isocyanate groups can be suppressed, the reaction with a chain extender other than water is efficiently advanced, and the urethane prepolymer (C2) is increased in molecular weight. It becomes possible.
In particular, when a chain extension reaction is carried out using polyamines as chain extenders, the temperature in the reaction system is 20 to 70 ° C. (more preferably 20 to 50 ° C.) because the reactivity between the polyamine and the isocyanate group is high. ) Is preferable.
When using a polyamine that dissolves in water, the chain extension reaction can be carried out by mixing the polyamine with an appropriate amount of water and gradually introducing the solution while dripping the solution into the reaction system. It is preferable from the viewpoint of gelation suppression.

(Polymerization reaction)
The polymerization reaction is usually preferably performed at a temperature of 40 to 100 ° C.
In carrying out the polymerization reaction, a polymerization initiator is usually used. The polymerization initiator may be water-soluble or oil-soluble.
Examples of the polymerization initiator include azo compounds such as azobisisobutyronitrile and azobisisobutylvaleronitrile; benzoyl peroxide, isobutyryl peroxide, octanoyl peroxide, cumylperoxyoctate, t-butylperoxy- Organic peroxides such as 2-ethylhexanoate, t-butylperoxyacetate, lauryl peroxide, di-t-butylperoxide, di-2-ethylhexylperoxydine carbonate; potassium persulfate, ammonium persulfate, peroxysulfate And inorganic peroxide compounds such as hydrogen oxide.
An organic peroxide or an inorganic peroxide compound can also be used as a redox initiator in combination with a reducing agent. For example, a redox initiator is preferable when the polymerization reaction is performed at a relatively low temperature of 70 ° C. or lower (for example, when a chain extension reaction using water as a chain extender is performed simultaneously) or when the polymerization rate is to be accelerated. Examples of the reducing agent used in this case include L-ascorbic acid, L-sorbic acid, sodium metabisulfite, ferric sulfate, ferric chloride, Rongalite and the like.
These polymerization initiators can be used singly or in combination of two or more.
The polymerization initiator is preferably used within a range of 0.05 to 5.00 parts by mass with respect to 100 parts by mass of the monomer composition (A).

When an oil-soluble polymerization initiator is used as the polymerization initiator, it is dissolved in the liquid mixture (II) containing the urethane prepolymer (C2) and the monomer composition (A) before adding water in Step 2. It is preferable to keep it.
When a water-soluble polymerization initiator is used as the polymerization initiator, after adding water to the mixture (II) containing the urethane prepolymer (C2) and the monomer composition (A), that is, after the neutralization / emulsification step It is preferable to add a polymerization initiator to the obtained dispersion (after the chain extension reaction when the chain extension reaction is performed using a chain extender other than water).
Addition of the polymerization initiator is a method of adding the whole amount of the polymerization initiator at once, a method of dropping the whole amount of the polymerization initiator over time, first adding a part of the polymerization initiator and adding the rest later. Any method may be used.

In the polymerization reaction, a chain transfer agent may be used for the purpose of adjusting the molecular weight.
As the chain transfer agent, for example, known chain transfer agents such as octyl mercaptan, lauryl mercaptan, 2-mercaptoethanol, tert-dodecyl mercaptan, and thioglycolic acid can be used.

In the polymerization reaction, when the emulsifying power of the urethane prepolymer (C2) is low, aggregates and cullet may be generated during the polymerization, and the production stability may be lowered.
Therefore, the polymerization reaction is preferably performed in the presence of an emulsifier. Thereby, generation | occurrence | production of the aggregate and cullet can be reduced.
As the emulsifier, a reactive emulsifier is preferable from the viewpoint of water resistance and weather resistance of the dried coating film.
As the reactive emulsifier, for example, a reactive emulsifier having an allyl group in the molecule as a reaction site can be used. Specifically, “ADEKA rear soap SR-10”, “ER-10”, “ER-30”, etc., manufactured by ADEKA Corporation are listed.
In addition, as the reactive emulsifier, an anionic reactive emulsifier having an alkenyl group or the like as a reaction site can also be used. Specific examples include “Latemul PD-104” manufactured by Kao Corporation.
The amount of the reactive emulsifier used is the polymerization stability during the production of the urethane prepolymer (C2) in terms of the water resistance and weather resistance of the coating film, and when the reactive emulsifier is used in the neutralization / emulsification step of Step 2. Therefore, the amount is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the monomer composition (A).

3-50 mass% is preferable and, as for the solid content concentration (resin solid content) of the aqueous resin dispersion immediately after finishing polymerization reaction, 20-50 mass% is more preferable. When the solid content concentration is 3% by mass or more, when the reaction solution is used as it is as an aqueous resin dispersion for forming a dry coating film, a film thickness effective for improving coating film properties can be obtained. On the other hand, when the solid content concentration is 50% by mass or less, the radical polymerization of the monomer composition (A) can be stably performed, and the viscosity of the obtained aqueous resin dispersion easily falls within the preferable range described below. Workability is improved.
The solid content concentration (resin solid content) of the aqueous resin dispersion can be obtained by the formula (i) described in Examples below.

The viscosity (25 ° C.) of the aqueous resin dispersion immediately after finishing the polymerization reaction is preferably 5 to 1000 mPa · s, more preferably 5 to 100 mPa · s. Within the above range, when the aqueous resin dispersion is used for coating, it can be used in a state of high solid content without being diluted more than necessary, and a film thickness effective in improving physical properties can be obtained.
The viscosity of the aqueous resin dispersion is determined by the measurement method described in the examples below.

6-10 are preferable and, as for the value of pH (25 degreeC) of the aqueous resin dispersion immediately after finishing a polymerization reaction, 7-9 are more preferable. When it is at least the lower limit (pH 6) of the above range, the storage stability of the aqueous resin dispersion is improved, and when it is not more than the upper limit (pH 10), the viscosity of the aqueous resin dispersion is lowered and it is easy to handle.
The pH of the aqueous resin dispersion is determined by the measurement method described in the examples below.

[Production Method of Second Aspect]
The production method of the second aspect of the present invention (hereinafter also referred to as production method (2)) includes the following step 1, step 4 and step 5.
Step 1: In the monomer composition (A) containing the (meth) acrylic monomer, the polyol (a) (component (a)) is reacted with the acid anhydride (b) (component (b)). The process of producing the polyol (B) which has a carboxy group, and obtaining the liquid mixture (I) containing the said monomer composition (A) and the said polyol (B).
Process 4: In the liquid mixture (I) obtained at the process 1, the said polyol (B) and polyisocyanate (c) ((c) component) are made to react, and the urethane prepolymer (C4 which has a carboxy group) ) To obtain a mixed liquid (IV) containing the monomer composition (A) and the urethane prepolymer (C4).
Step 5: The mixture (IV) obtained in Step 4 is emulsified by adding a neutralizing agent and water, and then the compound (d) (component (d)) having a glycidyl group and a polymerizable unsaturated group is used. A step of performing a reaction with the urethane prepolymer (C4) and a polymerization reaction to obtain an aqueous urethane-modified (meth) acrylic resin dispersion (aqueous resin dispersion).

In the production method (2), a polyol (B) having a carboxy group is first produced in a monomer composition (A) containing a (meth) acrylic monomer, and then a urethane prepolymer (C4 having a carboxy group). Then, neutralization and emulsification of the carboxy group are performed by adding a neutralizing agent and water, and then the reaction between the component (d) and the urethane prepolymer (C4) and the polymerization reaction are performed. (D) By the reaction with a urethane prepolymer (C4), the urethane prepolymer which has a carboxy group and a polymerizable unsaturated group produces | generates similarly to the said urethane prepolymer (C2). By the polymerization reaction, the monomer and the urethane prepolymer (having a carboxy group and a polymerizable unsaturated group) constituting the monomer composition (A) are polymerized, and the urethane-modified (meth) acryl is bonded to the acrylic resin and the urethane resin. An aqueous resin dispersion in which the resin is dispersed in water is obtained.
The production method (2) is the same as the production method (1) except that the component (d) is not reacted in the step 2, but is reacted after the neutralization / emulsification step in the step 3.
The description of the monomer composition (A) and the components (a) to (d) and the step 1 in the production method (2) is the same as in the production method (1) described above.
Hereinafter, Steps 4 to 5 will be described in detail.

<< Process 4 >>
In step 4, the polyol (B) and the component (c) are reacted in the mixed liquid (I) obtained in step 1. Thereby, the urethane prepolymer (C4) which has a carboxy group derived from a polyol (B) produces | generates.
Step 4 is carried out continuously after step 1, and the reaction proceeds in the monomer composition (A). Therefore, a mixed liquid (IV) containing the monomer composition (A) and the urethane prepolymer (C4) is obtained by the above reaction.
The reaction (urethanization reaction) between the polyol (B) and the component (c) in step 4 can be performed in the same manner as the urethanization reaction in step 2 described above.
The preferred acid value and number average molecular weight of the urethane prepolymer (C4) are the same as those of the urethane prepolymer (C2).

In the mixed liquid (IV), the mass ratio of the urethane prepolymer (C4) to the monomer composition (A) is within the range of urethane prepolymer (C4): monomer composition (A) = 20: 80 to 90:10. The urethane prepolymer (C4): monomer composition (A) is more preferably within the range of 30:70 to 70:30.
If each component is blended so that the mass ratio of the urethane prepolymer (C4) and the monomer composition (A) is within the above range, Step 4 and Step 5 can be performed stably, and the resulting aqueous resin dispersion The liquid stability is good. Moreover, the solvent resistance and water resistance of the coating film formed from the aqueous resin dispersion are also good.
In addition, the monomer composition at the time of the emulsification process in the process 5 that the ratio of a urethane prepolymer (C4) is more than the lower limit (urethane prepolymer (C4): monomer composition (A) = 20: 80) of the said range. The dispersion stability of the product (A) is improved, so that the occurrence of cullet during the radical polymerization reaction is suppressed, and the production stability is improved. On the other hand, if the ratio of the urethane prepolymer (C4) is not more than the upper limit of the above range (urethane prepolymer (C4): monomer composition (A) = 90: 10), the system during the urethanization reaction in step 4 The inside viscosity does not become too high, and the urethanization reaction can be performed stably. Moreover, also in the following process 5, the viscosity increase by neutralization is suppressed and the emulsification process can be performed stably.

<< Process 5 >>
In step 5, first, a neutralizing agent and water are added to the mixed liquid (IV) obtained in step 4 to emulsify (neutralization / emulsification step). Thereby, while the carboxy group of urethane prepolymer (C4) in liquid mixture (IV) is neutralized, the dispersion liquid which liquid mixture (IV) disperse | distributed in water is obtained.
After the neutralization / emulsification step, a reaction (addition reaction) and a polymerization reaction (addition / polymerization step) between the component (d) and the urethane prepolymer (C4) are performed. Thereby, in the dispersion liquid, a urethane prepolymer having a carboxy group and a polymerizable unsaturated group derived from the component (d) is generated, and the monomer constituting the monomer composition (A) and the urethane prepolymer (carboxy) Group having a polymerizable group and a polymerizable unsaturated group) is radically polymerized to obtain an aqueous resin dispersion in which a urethane-modified (meth) acrylic resin in which an acrylic resin and a urethane resin are bonded is dispersed in water.
If necessary, a chain extension reaction of the neutralized urethane prepolymer (C4) may be performed after the neutralization / emulsification step and before the addition / polymerization step.

The neutralization / emulsification step can be performed in the same manner as the neutralization / emulsification step in step 3.
The chain extension reaction can be performed in the same manner as the chain extension reaction in Step 3.
The addition reaction and polymerization reaction in the addition / polymerization step can be carried out in the same manner as the addition reaction in step 2 and the polymerization reaction in step 3, respectively. For example, when using an oil-soluble polymerization initiator as a polymerization initiator for the polymerization reaction, a liquid mixture containing the urethane prepolymer (C4) and the monomer composition (A) in advance before adding water in the neutralization / emulsification step. It is preferable to dissolve in (IV). When a water-soluble polymerization initiator is used as the polymerization initiator, after adding water to the mixed liquid (IV) containing the urethane prepolymer (C4) and the monomer composition (A), that is, after the neutralization / emulsification step It is preferable to add a polymerization initiator to the obtained dispersion (after the chain extension reaction when the chain extension reaction is performed using a chain extender other than water).
The addition reaction and the polymerization reaction may be performed simultaneously, or the polymerization reaction may be performed after the addition reaction. As a method of performing the addition reaction and the polymerization reaction simultaneously, for example, before the neutralization / emulsification step, the component (d) is added to the liquid mixture (IV) in advance, and after the neutralization / emulsion step, A method of setting to a predetermined reaction temperature (a temperature at which an addition reaction and a polymerization reaction proceed, for example, 50 to 100 ° C.) is exemplified.

The solid content concentration (resin solid content) of the aqueous resin dispersion immediately after the completion of the polymerization reaction is preferably 3 to 50% by mass, and more preferably 20 to 50% by mass, as in the production method (1).
The viscosity (25 ° C.) of the aqueous resin dispersion immediately after finishing the polymerization reaction is preferably 5 to 1000 mPa · s, more preferably 5 to 100 mPa · s, as in the production method (1).
The value of pH (25 ° C.) of the aqueous resin dispersion immediately after finishing the polymerization reaction is preferably 6 to 10, more preferably 7 to 9, as in the production method (1).

[Function and effect]
According to the production method (1) or (2), the aqueous resin dispersion can be produced stably.
For example, when producing a urethane prepolymer, the generation of precipitates accompanying the progress of the urethanization reaction (step 2 or 4) with a (meth) acrylic monomer can be suppressed. Further, it is possible to suppress the increase in viscosity or gelation of the dispersion obtained in the subsequent emulsification step (step 3 or 5) and the generation of aggregates. Therefore, these steps can be continued stably.
Further, according to the production method (1) or (2), an aqueous resin dispersion having good liquid stability such as alcohol shock resistance, durability against freeze-thaw cycles, and thermal stability can be obtained.
Furthermore, according to the production method (1) or (2), an aqueous resin dispersion capable of forming a coating film having good solvent resistance and water resistance can be obtained.

[Aqueous urethane-modified (meth) acrylic resin dispersion]
The aqueous urethane-modified (meth) acrylic resin dispersion (aqueous resin dispersion) according to the third aspect of the present invention is obtained by the production method (1) or (2).
As a method for producing the aqueous resin dispersion of this embodiment, production method (1) is preferred because the addition reaction of component (d) proceeds efficiently and more excellent liquid stability can be obtained.

The aqueous resin dispersion of this embodiment can be used as a coating agent, paint, ink or the like as it is or with additives added as necessary.
As an additive, it can select suitably from well-known additives according to a use.
In addition, when using an aqueous resin dispersion as a coating agent, a coating material, ink, etc., although it does not specifically limit about the resin solid content of a urethane-modified (meth) acrylic resin, Usually, it is 3-50 mass%. When the resin solid content is too high, water or an organic solvent may be blended in the aqueous resin dispersion so as to obtain a desired value, and may be used after dilution.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.
In this example, “part” means “part by mass” unless otherwise specified.
Various measurement methods and evaluation methods are as follows.

<Measurement of physical properties of urethane prepolymer>
(Measurement of number average molecular weight)
The monomer composition (A) mixture of urethane prepolymer was measured by gel permeation chromatography (produced by Tosoh Corporation, converted to polystyrene), the peak that appeared on the highest molecular weight side was regarded as the urethane prepolymer, and the number average molecular weight Asked.

<Measurement of physical properties of aqueous urethane-modified (meth) acrylic resin dispersion>
(Measurement of resin solids)
The mass of the aqueous resin dispersion obtained in advance was measured. Next, the dispersion was dried at a temperature within the range of 105 ± 5 ° C. for 2 hours, the mass of the dried residue was measured, and the resin solid content was determined by the following formula (i).
Resin solid content (mass%) = mass of dry residue (g) / mass of dispersion before drying (g) × 100 (i)

(Measurement of viscosity)
The aqueous resin dispersion is allowed to stand at a temperature within a range of 25 ± 1 ° C. for 2 hours, and then is aqueous using a B-type viscometer (“TV-22 viscometer spindle type” manufactured by Toki Sangyo Co., Ltd.). The viscosity (unit: mPa · s) of the resin dispersion was measured.

(Measurement of pH)
After leaving the aqueous resin dispersion at a temperature in the range of 25 ± 1 ° C. for 2 hours, the pH of the aqueous resin dispersion is adjusted using a pH meter (“G series HM-30G” manufactured by Toa DKK Corporation). It was measured.

<Evaluation of manufacturing stability>
Based on the following evaluation criteria, the production stability of each step up to the production of the aqueous resin dispersion was evaluated.
(Urethanization reaction step: Step 1, 2 or Step 1, 4)
In Step 1, Step 2 and Step 4, the state of the solution in the reaction system (solubility of raw materials, generation of precipitates, etc.) from the start of raw material supply until the end of the predetermined reaction time is visually observed, and the following evaluation is performed. The production stability was evaluated based on the criteria.
{Evaluation criteria}
5: The reaction solution remains transparent until the end of the urethanization reaction, and no precipitate is generated, and the production stability is good.
4: Although the reaction solution becomes slightly turbid due to the progress of the urethanization reaction, no precipitate is generated, and there is no problem in the stability of production.
3: Due to the progress of the urethanization reaction, the reaction solution becomes cloudy, and a small amount of precipitates are generated, resulting in a slight decrease in production stability.
2: The reaction solution becomes cloudy due to the progress of the urethanization reaction, and a large amount of precipitates are generated, resulting in a decrease in production stability.
1: During the urethanization reaction, the raw materials are not completely dissolved, or a large amount of precipitates are generated, and the reaction cannot be continued.

(Emulsification step: Step 3 or Step 5)
In the step of adding the neutralizing agent and water to the mixture containing the urethane prepolymer and the monomer composition (A) to emulsify the urethane prepolymer, the dispersion in the reaction system after adding all of the neutralizing agent and water. The conditions (viscosity, generation of aggregates, resin adhesion to the inner wall of the reactor and stirring blades, etc.) were visually observed, and the production stability was evaluated based on the following evaluation criteria.
{Evaluation criteria}
5: The viscosity of the dispersion is low, there is no generation of aggregates and no resin adheres to the reactor, and the production stability is good.
4: Although the viscosity of the dispersion becomes slightly high, there is no problem in the stability of production because there is no generation of aggregates and adhesion of the resin to the reactor.
3: The viscosity of the dispersion becomes slightly high, and further, the generation of aggregates and a small amount of resin adhesion to the reactor occur, resulting in a slight decrease in production stability.
2: Viscosity of the dispersion becomes slightly high, and further generation of agglomerates and adhesion of resin to the reactor occur, resulting in a decrease in production stability.
1: Continued emulsification becomes impossible because the viscosity of the dispersion becomes extremely high or gels, or large aggregates are generated and stirring becomes impossible.

(Radical polymerization step: Step 3 or Step 5)
In the radical polymerization reaction of the urethane prepolymer and the monomer composition (A), the state of the liquid in the reaction system (viscosity, adhesion of cullet to the inner wall of the reactor and stirring blades, etc.) is visually observed, and cullet is further treated as follows. Was measured, and the stability of production was evaluated based on the following evaluation criteria.
The occurrence rate of cullet is determined by filtering the dispersion using a 150 mesh nylon candy after production, collecting the aggregate, and then drying the collected aggregate at a temperature within the range of 105 ± 5 ° C. for 2 hours. The mass of the remainder was measured, and the occurrence rate was determined by the following formula (ii).
Rate of occurrence of cullet (% by mass) = mass of dry residue (g) / mass of charged monomer (g) × 100 (ii)

{Evaluation criteria}
5: The occurrence rate of cullet is less than 0.2% by mass. Almost no cullet adheres to the reactor and the stirring blade, and the production stability is good.
4: The occurrence rate of cullet is not less than 0.2% by mass and less than 0.5% by mass, and there is almost no adhesion of cullet to the reactor and the stirring blade, and there is no problem in the stability of production.
3: The occurrence rate of cullet is 0.5% by mass or more and less than 1% by mass, and a small amount of cullet adheres to the reactor and the stirring blade, so that the production stability is slightly lowered.
2: The occurrence rate of cullet is 1% by mass or more and less than 3% by mass, and a large amount of cullet adheres to the reactor and the stirring blade, resulting in a decrease in production stability.
1: The occurrence rate of cullet is 3% by mass or more, and a large amount of cullet adheres to the reactor and the stirring blade, resulting in extremely poor production stability.

<Liquid stability test>
(Evaluation of alcohol shock resistance)
Aqueous resin dispersion / isopropyl alcohol = 1/1 (mass ratio) or aqueous resin dispersion / methanol = 1/1 (mass ratio), and each is stirred to prepare an alcohol blend of aqueous resin dispersion did.
Subsequently, after leaving the obtained alcohol compounding liquid still at 25 degreeC for 2 hours, the viscosity of the alcohol compounding liquid was measured using the B-type viscometer. And the increase rate of the viscosity after alcohol mixing with respect to the viscosity of the aqueous resin dispersion before alcohol mixing was calculated | required. Further, the presence or absence of aggregates was visually observed. From these results, alcohol shock resistance was evaluated based on the following evaluation criteria.
{Evaluation criteria}
5: Viscosity increase rate is less than 50%, and aggregates are not generated.
4: The rate of increase in viscosity is 50% or more and less than 200%, and aggregates are not generated.
3: The viscosity increase rate is 200% or more and less than 500%, and aggregates are not generated.
2: The viscosity increase rate is 500% or more, and aggregates are not generated.
1: Gelled. Alternatively, a large amount of aggregate was generated.

(Evaluation of durability against freeze-thaw cycles)
The aqueous resin dispersion was completely frozen at 0 ° C. and then allowed to stand in hot water at 50 ° C. for 2 hours for dissolution. This operation was repeated 5 times to prepare a solution after the freeze-thaw cycle of the aqueous resin dispersion.
Next, after the obtained solution after freeze-thaw cycle was allowed to stand at 25 ° C. for 2 hours, the viscosity of the solution after freeze-thaw cycle was measured using a B-type viscometer. And the increase rate of the viscosity after a freeze thaw cycle with respect to the viscosity of the aqueous resin dispersion before a freeze thaw cycle was calculated | required. Further, the presence or absence of aggregates was visually observed. From these results, durability against freeze-thaw cycles was evaluated based on the following evaluation criteria.
{Evaluation criteria}
5: The rate of increase in viscosity is less than 10%, and aggregates are not generated.
4: The rate of increase in viscosity is 10% or more and less than 30%, and aggregates are not generated.
3: The viscosity increase rate is 30% or more and less than 50%, and aggregates are not generated.
2: The viscosity increase rate is 50% or more, and aggregates are not generated.
1: A large amount of gelation or aggregation occurred.

(Evaluation of thermal stability)
The aqueous resin dispersion was allowed to stand at 50 ° C. for 15 days. The aqueous resin dispersion after standing at 50 ° C. was allowed to stand at 25 ° C. for 2 hours, and then the viscosity of the aqueous resin dispersion was measured using a B-type viscometer. And the increase rate of the viscosity after 50 degreeC standing with respect to the viscosity of the aqueous resin dispersion before 50 degreeC standing was calculated | required. Further, the presence or absence of aggregates was visually observed. From these results, thermal stability was evaluated based on the following evaluation criteria.
{Evaluation criteria}
5: The rate of increase in viscosity is less than 10%, and aggregates are not generated.
4: The rate of increase in viscosity is 10% or more and less than 30%, and aggregates are not generated.
3: The viscosity increase rate is 30% or more and less than 50%, and aggregates are not generated.
2: The viscosity increase rate is 50% or more, and aggregates are not generated.
1: A large amount of gelation or aggregation occurred.

<Coating test>
(Evaluation of solvent resistance)
A clear coating was prepared by blending 15 parts of butyl cellosolve with 100 parts of the aqueous resin dispersion.
Then, a clear coating was applied to the treated PET sheet whose surface was wiped with methanol using a bar coater so that the dry film thickness was 20 μm, and dried at 70 ° C. for 40 minutes to obtain a coating film for evaluation.
After rubbing a gauze impregnated with any of toluene, methyl ethyl ketone, ethyl acetate, and isopropyl alcohol on the evaluation coating film 50 times, the appearance change of the coating film was observed visually, and the following evaluation criteria were satisfied. Based on this, the solvent resistance was evaluated.
{Evaluation criteria}
5: No cloudiness or whitening.
4: There is very little clouding or whitening, but there is no problem.
3: Cloudiness and whitening are recognized.
2: It is considerably whitened.
1: Scratch and whitening of the coating are severe.

(Evaluation of water resistance)
An evaluation coating film was obtained in the same manner as in the solvent resistance evaluation.
After rubbing the gauze soaked with deionized water 100 times with a load of 1 kg on the evaluation coating film, the appearance change of the coating film was visually observed, and the water resistance of the coating film was evaluated based on the following evaluation criteria. Evaluation was performed.
{Evaluation criteria}
5: No cloudiness or whitening.
4: There is very little clouding or whitening, but there is no problem.
3: Cloudiness and whitening are recognized.
2: It is considerably whitened.
1: Scratch and whitening of the coating are severe.

[Example 1]
An aqueous resin dispersion (P-1) was produced by the following procedure. The manufacturing method of this example is a method (hereinafter, also referred to as manufacturing method (1-1)) in which step 2 in manufacturing method (1) is performed by method (2-1).

(Step 1: Production of polyol (B))
In a four-necked flask equipped with a stirrer, a thermometer, and a condenser, 5.3 parts of (a) component trimethylolpropane, a number obtained from a high molecular weight polyol (3-methyl-1,5-pentanediol and sebacic acid) 15.4 parts of polyester diol having an average molecular weight of 1000. Hereinafter referred to as “polyester diol”), 5 parts of component (b) succinic anhydride, and 17.3 parts of methyl methacrylate of monomer composition (A). 17.3 parts of isobutyl methacrylate, 17.3 parts of ethyl acrylate, 6.85 parts of normal butyl acrylate, and 0.5 part of dimethylaminoethyl methacrylate were charged. The mixture was heated to 90 ° C. with stirring and held for 3 hours to carry out an addition reaction to obtain a monomer composition (A) solution of polyol (B).

(Step 2: Urethane reaction by method (2-1) and addition reaction of component (d))
Next, 14.3 parts of (c) component isophorone diisocyanate was added dropwise to the reactor over 30 minutes. After the addition, the temperature in the reactor was lowered from 90 ° C. to 80 ° C., and maintained at 80 ° C. for 3 hours. A urethanization reaction was performed to obtain a monomer composition (A) solution of a urethane prepolymer having a carboxy group.
Next, 0.75 part of glycidyl methacrylate as component (d) was added to the reactor, and the addition reaction was carried out at 80 ° C. for 2 hours to obtain a urethane prepolymer (C2) having a carboxy group and a polymerizable unsaturated group. A monomer composition (A) solution (mixed solution (II)) was obtained.

(Process 3: Neutralization / Emulsification process)
Next, the mixed liquid (II) is cooled until the internal temperature becomes 50 ° C. or less, and a solution (triethylamine aqueous solution) in which 5.2 parts of triethylamine and 174 parts of deionized water are mixed is dropped over 30 minutes. And emulsified.

(Step 3: radical polymerization reaction)
After the solution was uniformly emulsified, a solution in which 0.15 part of potassium persulfate was dissolved in 3 parts of deionized water (potassium persulfate aqueous solution) was added to the system, and the temperature was gradually raised. After confirming the exotherm, the temperature was controlled at 75 ° C. and held for 1 hour to perform radical polymerization and chain extension reaction with water. Thereafter, a solution (potassium persulfate aqueous solution) in which 0.15 part of potassium persulfate was dissolved in 3 parts of deionized water was further added, and radical polymerization was performed for 1.5 hours to obtain an aqueous resin dispersion (P-1). It was. The radical polymerization was terminated by setting the temperature of the reaction system to 40 ° C. or lower.

[Example 2] to [Example 13]
Aqueous resin dispersions (P-2 to P-13) were obtained by the same production method as in Example 1 except that the composition of the raw materials used was changed to the compositions shown in Tables 1 and 3.

[Example 14]
In step 2, first, the addition reaction between polyol (B) and component (d) was performed, and then the urethanization reaction was performed by adding polyisocyanate (c). Thus, an aqueous resin dispersion (P-14) was obtained.
The manufacturing method of this example is a method (hereinafter, also referred to as manufacturing method (1-2)) in which step 2 in manufacturing method (1) is performed by method (2-2).

[Example 15]
An aqueous resin dispersion (P-15) was produced by the following procedure. In this example, the manufacturing method (2) is adopted.

(Step 1: Production of polyol (B))
In a four-necked flask equipped with a stirrer, a thermometer, and a condenser, 5.3 parts of (a) component trimethylolpropane, 15.4 parts of polyester-based diol, (b) 5 parts of succinic anhydride, The monomer composition (A) was charged with 17.3 parts of methyl methacrylate, 17.3 parts of isobutyl methacrylate, 17.3 parts of ethyl acrylate, 6.85 parts of normal butyl acrylate, and 0.5 part of dimethylaminoethyl methacrylate. It is. The mixture was heated to 90 ° C. with stirring and held for 3 hours to carry out an addition reaction, whereby a monomer composition (A) solution of polyol (B) was obtained.

(Process 4: Urethane reaction)
Next, 14.3 parts of (c) component isophorone diisocyanate was added dropwise to the reactor over 30 minutes. After the addition, the temperature in the reactor was lowered from 90 ° C. to 80 ° C., and maintained at 80 ° C. for 3 hours. A urethanization reaction was performed to obtain a monomer composition (A) solution (mixed liquid (IV)) of a urethane prepolymer (C4) having a carboxy group.

(Step 5: Addition of component (d))
Next, 0.75 part of glycidyl methacrylate as component (d) was added to the reactor and mixed uniformly.

(Process 5: Neutralization / Emulsification process)
Next, the liquid mixture (IV) is cooled until the internal temperature becomes 50 ° C. or lower, and a solution (triethylamine aqueous solution) in which 5.2 parts of triethylamine and 174 parts of deionized water are mixed is dropped over 30 minutes. And emulsified.

(Step 5: addition reaction of component (d), radical polymerization reaction)
After the solution was uniformly emulsified, a solution in which 0.15 part of potassium persulfate was dissolved in 3 parts of deionized water (potassium persulfate aqueous solution) was added to the system, and the temperature was gradually raised. After confirming the exotherm, the temperature was controlled at 75 ° C. and held for 1 hour, and an addition reaction of component (d), radical polymerization, and chain extension reaction with water were performed. Thereafter, a solution (potassium persulfate aqueous solution) in which 0.15 part of potassium persulfate was dissolved in 3 parts of deionized water was further added, and radical polymerization was performed for 1.5 hours to obtain an aqueous resin dispersion (P-15). It was. The radical polymerization was terminated by setting the temperature of the reaction system to 40 ° C. or lower.

[Example 16], [Example 17], [Example 19] to [Example 25]
Aqueous resin dispersions (P-16, P-17, P-19 to P-25) were obtained by the same production method as in Example 1 except that the compositions shown in Tables 3 and 5 were changed.

[Example 18]
It changed into the composition shown in Table 3, and performed from the process 1 to the process 3 (neutralization / emulsification process) with the manufacturing method similar to [Example 1].

(Step 3: Chain extension reaction)
After the solution was uniformly emulsified, a solution in which 1 part of ethylenediamine was dissolved in 1.5 parts of deionized water was added to the system, and the chain temperature was reacted for 30 minutes while controlling at an internal temperature of 50 ° C.

(Step 3: radical polymerization reaction)
Next, a solution (potassium persulfate aqueous solution) in which 0.15 part of potassium persulfate was dissolved in 1.5 parts of deionized water was added to the system, and the temperature was gradually raised. After confirming the exotherm, the temperature was controlled at 75 ° C. and held for 1 hour to perform radical polymerization. Thereafter, a solution (potassium persulfate aqueous solution) in which 0.15 part of potassium persulfate was dissolved in 3 parts of deionized water was further added, and radical polymerization was performed for 1.5 hours to obtain an aqueous resin dispersion (P-18). It was. The radical polymerization was terminated by setting the temperature of the reaction system to 40 ° C. or lower.

[Comparative Example 1]
(B) Instead of the component, dimethylolbutanoic acid was used, and the dispersion (P-26) was prepared in the same manner as in Example 1 except that the other raw materials were changed to the compositions shown in Table 7. Obtained.

[Comparative Example 2]
In place of the component (d), 1,4-butenediol was used, and other raw materials were changed to the compositions shown in Table 7, and the dispersion (P-27) was prepared by the same production method as in Example 1. Obtained.

Tables 1, 3, 5, and 7 show the names and compositions of the raw materials used in Examples 1 to 25 and Comparative Examples 1 and 2. In the table, “EO” represents ethylene oxide, and “PO” represents propylene oxide.
Moreover, the mass ratio of the urethane prepolymer and the monomer composition (A) in each example, the molar ratio of the hydroxyl group in the component (a) to the acid anhydride group in the component (b), the acid value of the urethane prepolymer ( Solid content conversion, unit: mgKOH / g), (d) molar ratio of glycidyl group in component to carboxy group in polyol (B), (c) isocyanate group and polyol (B) or (a) in component Tables 1, 3, 5, and 7 show the molar ratios with the hydroxyl groups in the components and the production methods (production methods (1-1), (1-2), or (2)) employed in each example.
In any example, the amount of triethylamine is 1 equivalent per 1 equivalent of carboxy groups in the urethane prepolymer.
The acid value of the urethane prepolymer is a theoretical value (theoretical acid value) determined by the following formula (iii).
Theoretical acid value of urethane prepolymer (mgKOH / g)
= ((B) Component charge amount (parts) / (b) component molecular weight) × (b) component acid anhydride group number × 56100 × (1 / mass ratio of urethane prepolymer) (iii)

Moreover, in each example, the measurement result of the number average molecular weight of the urethane prepolymer obtained in the step 2 or 4, and the measurement of the resin characteristic values (resin solid content, viscosity, pH) in the aqueous resin dispersion obtained in each example The results are shown in Tables 2, 4, 6, and 7.
Further, Tables 2, 4, 6, and 7 show the production stability evaluation of the aqueous resin dispersions in each example, the liquid stability test results of the obtained aqueous resin dispersions, and the coating film test results.

As is clear from the above results, Examples 1 to 25 have good production stability of the aqueous resin dispersion, and liquid stability (alcohol shock resistance, freeze-thaw cycle) of the obtained aqueous resin dispersion. Durability and heat stability). Moreover, the coating film formed from these aqueous resin dispersions had good solvent resistance and water resistance.
On the other hand, in Comparative Example 1 using dimethylolbutanoic acid instead of the component (b), a large amount of precipitates were generated during the urethanization reaction, and the production stability was extremely poor. Furthermore, in the subsequent emulsification step, aggregates were generated, making it impossible to continue the production.
In Comparative Example 2 in which 1,4-butenediol was used in place of the component (d) as a component for introducing a double bond group into the urethane prepolymer, the liquid stability of the obtained aqueous resin dispersion was extremely poor. It was. This is considered to be due to the following reason.
When an alkenediol such as 1,4-butenediol is used to introduce a polymerizable unsaturated group into the urethane prepolymer, a double bond is introduced into the main chain skeleton of the urethane prepolymer, ( The radical polymerization reactivity with the (meth) acrylic monomer is lowered. As a result, it is considered that the bonding amount between the urethane resin and the (meth) acrylic resin is reduced, and the liquid stability of the aqueous resin dispersion is lowered.

In Examples 1 to 25, when comparing Examples 1 to 5 in which the molar ratio of the hydroxyl group in the component (a) and the acid anhydride group in the component (b) was changed, hydroxyl group: acid anhydride group = 3 In Example 1, the stability of the urethanization reaction step, the liquid stability of the obtained aqueous resin dispersion, the solvent resistance and the water resistance of the coating film were the best.
When Example 1 is compared with Examples 6 to 9 in which the amount of the component (d) is changed with respect to Example 1, the liquid stability of the aqueous resin dispersion in Example 6 with the largest amount of glycidyl groups is shown. The property was the best.
When Example 1 is compared with Examples 10 and 11 in which the acid value of the urethane prepolymer was changed with respect to Example 1, in Example 11 in which the acid value of the urethane prepolymer was the lowest, Good solvent resistance and water resistance.
When Example 1 is compared with Examples 12 and 13 in which the mass ratio of the urethane prepolymer and the monomer composition (A) is changed with respect to Example 1, the ratio of the monomer composition (A) is the highest. In Example 13, the solvent resistance and water resistance of the coating film were the best.
When Example 1 was compared with Examples 14 and 15 in which the production method was changed with respect to Example 1, the production stability was good. The liquid stability of the aqueous resin dispersion and the solvent resistance and water resistance of the coating film were the best in Example 1 employing the production method (1-1).

When Example 1 is compared with Examples 16 and 17 in which the molar ratio of isocyanate groups and hydroxyl groups is changed with respect to Example 1, Examples 1 and 16 having a relatively high isocyanate group ratio are From the low Example 17, the solvent resistance and water resistance of the coating film were good.
Comparing Example 18 using ethylenediamine as a chain extender and Example 16 having substantially the same conditions except that ethylenediamine was not used, Example 18 is more solvent-resistant than the Example 16 than the solvent resistance of the coating film. Improved water resistance.
When Example 1 is compared with Examples 19 to 21 in which the high molecular weight polyol was not used as the component (a), the solvent resistance and water resistance of the coating film of Example 1 using the high molecular weight polyol were higher. It was good.
When Example 1 is compared with Examples 22 and 23 in which succinic anhydride was not used as the component (b), the stability of the aqueous resin dispersion was better in Example 1 using succinic anhydride. Met.
When Example 1 was compared with Examples 24 and 25 in which glycidyl methacrylate was not used as the component (d), Example 1 using glycidyl methacrylate had better liquid stability of the aqueous resin dispersion. It was.

  According to the present invention, a urethane prepolymer having a carboxy group can be stably produced in a monomer composition containing a (meth) acrylic monomer, followed by neutralization and emulsification, and finally radical polymerization. By performing, an aqueous urethane-modified (meth) acrylic resin dispersion containing no organic solvent can be produced. This dispersion has properties excellent in alcohol shock resistance, durability against freeze-thaw cycles, and heat stability, and the coating film obtained from this dispersion is excellent in solvent resistance and water resistance. . Therefore, it becomes industrially useful as a water-based resin for coating agents, paints, and inks.

Claims (4)

A method for producing an aqueous urethane-modified (meth) acrylic resin dispersion, comprising the following step 1, step 2 and step 3.
Step 1: In the monomer composition (A) containing a (meth) acrylic monomer, the polyol (a) and the acid anhydride (b) are reacted to produce a polyol (B) having a carboxy group, The process of obtaining the liquid mixture (I) containing the said monomer composition (A) and the said polyol (B).
Step 2: In the mixed liquid (I) obtained in Step 1, the polyol (B), the polyisocyanate (c), and the compound (d) having a glycidyl group and a polymerizable unsaturated group are reacted. The process which produces | generates the urethane prepolymer (C2) which has a carboxy group and a polymerizable unsaturated group, and obtains the liquid mixture (II) containing the said monomer composition (A) and the said urethane prepolymer (C2).
Step 3: A step of adding a neutralizing agent and water to the mixed liquid (II) obtained in Step 2 to emulsify, and then performing a polymerization reaction to obtain an aqueous urethane-modified (meth) acrylic resin dispersion. A method for producing an aqueous urethane-modified (meth) acrylic resin dispersion, comprising the following step 1, step 4 and step 5.
Step 1: In the monomer composition (A) containing a (meth) acrylic monomer, the polyol (a) and the acid anhydride (b) are reacted to produce a polyol (B) having a carboxy group, The process of obtaining the liquid mixture (I) containing the said monomer composition (A) and the said polyol (B).
Step 4: In the mixed liquid (I) obtained in Step 1, the polyol (B) and the polyisocyanate (c) are reacted to produce a urethane prepolymer (C4) having a carboxy group, The process of obtaining liquid mixture (IV) containing a monomer composition (A) and the said urethane prepolymer (C4).
Step 5: The mixture (IV) obtained in Step 4 is emulsified by adding a neutralizing agent and water, and then the compound (d) having a glycidyl group and a polymerizable unsaturated group and the urethane prepolymer (C4). ) And a polymerization reaction to obtain an aqueous urethane-modified (meth) acrylic resin dispersion.   The aqueous urethane-modified (meth) acrylic according to claim 1 or 2, wherein the acid anhydride (b) is selected from the group consisting of succinic anhydride, methylhexahydrophthalic anhydride, and glycerin bisanhydro trimellitate monoacetate. A method for producing a resin dispersion.   An aqueous urethane-modified (meth) acrylic resin dispersion obtained by the production method according to any one of claims 1 to 3.