JP2871248B2 - Amino resin aqueous dispersion and curable aqueous paint using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous dispersion of a substantially water-insoluble amino resin and to a thermosetting aqueous coating composition containing the amino resin aqueous dispersion.

[0002]

2. Description of the Related Art Heretofore, amino resins such as melamine resins and guanamine resins have been suitably used as thermosetting components in resin compositions such as paints. Such an amino resin is usually dissolved in an organic solvent together with an alkyd resin, an acrylic resin, an epoxy resin or the like, and is used as a solvent-type paint or the like. The amino resin used as the thermosetting component is selected from melamine-based, benzoguanamine-based, and acetoguanamine-based resins in view of the physical properties of the cured product to be obtained, and is used by appropriately modifying them. On the other hand, in recent years, from the viewpoint of occupational safety and health or global environmental conservation, there has been an increasing movement to replace solvents used for paints and the like with water which has little influence on the environment and low danger such as ignition. Many types of water-based compounds such as polyester resins, acrylic resins, and epoxy resins can be seen as resins for water-based paints. In such an environment, it is natural that amino resins used as thermosetting components are required to be arbitrarily usable in water-based paints. In general, amino resins are modified with methylol by condensing with formaldehyde and hydrophilizing by introducing a hydroxyl group into the molecule. However, in general, when the number of methylol groups is too large, the water resistance of the cured coating film is deteriorated, and the amount of deformaldehyde accompanying the curing reaction is increased, which often causes a problem in workability. Further, if the hydrophilicity of the amino resin is not sufficient, the compatibility with other resins may be inferior, and the uniformity of the coating solution or the stability over time may be reduced. In such a case, the resulting cured product often cannot be expected to have uniformity, which causes problems such as devitrification and reduced durability of the coating.

[0003] Therefore, in many cases, a measure is taken to improve the compatibility with other resins and the stability with time by subjecting the methylolated amino resin to alkyl ether modification with a lower alcohol and reducing the degree of condensation. . However, in general, lower alkyl etherified compounds still have lower thermal stability than higher alkyl etherified compounds, and cause a problem in storage stability when used in paints and the like. In general, amino resins imparted with hydrophilicity by alkyl etherification with lower alcohols can be made more hydrophilic than higher alkyl etherified compounds, but are sufficiently sufficient for use in water-based paints and the like. In some cases, it is hard to say that it is water-soluble. Therefore, when such an alkyl etherified amino resin is used for a water-based paint or the like, the type or amount used in the resin composition that can be used is considerably limited, and the physical properties of the obtained cured product are also limited. Subject to considerable restrictions. Further, in order to ensure an appropriate number of amino resin components, a hydrophilic solvent such as alcohol must be added.

In order to overcome these restrictions, it is considered effective to stably disperse the amino resin in water and use it in the form of a so-called emulsion. Usually, when a hydrophobic substance is dispersed and emulsified in water, a low molecular weight surfactant is generally used as an emulsifier, and an emulsion having an appropriate particle size and good stability can be obtained.
However, since the surfactant used for emulsification dispersion is only adsorbed on the surface of the dispersed phase, sufficient water resistance of the cured product cannot be obtained. In such a case, the water resistance of the cured product can be improved by dispersing the amino resin using a polymer emulsifier such as an acrylic resin, and such a method is disclosed in JP-B-63-63586. ing. That is, a vinyl monomer having a carboxyl group in the molecule, such as acrylic acid or methacrylic acid, is copolymerized with another vinyl monomer in an amino resin solution, the epoxy resin is dissolved and neutralized, and water is added. To obtain an aqueous dispersion. In general, when an aqueous dispersion is obtained using a polymer emulsifier, the polymer emulsifier is chemically bonded to the surface of the dispersoid to take action of further improving the water resistance of the obtained cured product. In the above-described method, condensation between a carboxyl group in an acrylic resin and an amino resin is used as a means for forming a chemical bond between the polymer emulsifier and the surface of the dispersoid. In order for this reaction to proceed effectively, a large amount of carboxyl groups must be present in the acrylic resin, and the cured product obtained has poor water resistance. In addition, since the rate of the reaction between the carboxyl group and the amino resin varies depending on the reaction conditions, it is difficult to control the acid value of the acrylic resin which is a polymer emulsifier. Generally, since the acid value of a polymer emulsifier greatly affects the dispersion state and stability of a dispersion, strict control of the resin acid value is necessary to obtain a stable aqueous dispersion.
It is indispensable.

[0005]

DISCLOSURE OF THE INVENTION The present invention has the disadvantages of conventional aqueous amino resins, for example, 1) the hydrophilicity is not sufficient. Insufficient hydrophilicity, poor compatibility with other aqueous resin components, etc. or limited number of parts to solve it, or forced to add an organic solvent to improve compatibility I do. 2) The physical properties of the cured product are limited. Since it is an amino resin modified with a high degree of methylolation or modified with a lower alkyl ether, it has high condensability, and when it is used as a thermosetting component, the flexibility of the cured product is often poor. 3) A large amount of volatile formaldehyde. As described above, the reactivity is high, that is, the formation of formaldehyde by condensation of methylol groups is remarkable. As a result of intensive research to obtain an amino resin that can be suitably used as a thermosetting component in a water-based paint or the like, a novel amino resin aqueous dispersion having excellent properties and an aqueous solution using the same The paint was found and the present invention was completed.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an aqueous amino resin dispersion which can be suitably used as a thermosetting component in aqueous paints and inks, that is, in the presence of a substantially water-insoluble amino resin. Essential compounds include a compound having a carboxyl group and an ethylenic α, β-unsaturated double bond in the molecule, and a compound having a functional group capable of reacting with the amino resin and a ethylenic α, β-unsaturated double bond in the molecule. As an aqueous dispersion of an amino resin obtained by radical polymerization with another compound having an ethylenic α, β-unsaturated double bond in the molecule, neutralizing at least partially with a basic substance, and then converting to an aqueous solution. A compound having an amino group and an ethylenic α, β-unsaturated double bond in the molecule in the presence of a solid and a substantially water-insoluble amino resin; Radical polymerization is carried out with a compound having a reactive functional group and an ethylenic α, β-unsaturated double bond as an essential component, together with a compound having an ethylenic α, β-unsaturated double bond in the other molecule. The present invention relates to an aqueous amino resin dispersion obtained by at least partially neutralizing with a substance and then making it aqueous. Further, the present invention is characterized in that the resin solid content contains at least 5% by weight of the aqueous amino resin dispersion as an essential component, and is excellent in compatibility with other aqueous resins and has a high degree of curing. The present invention relates to a curable water-based paint that gives physical properties.

The aqueous amino resin dispersion of the present invention is different from the hydrophilic amino resin conventionally used for water-based paints, that is, the amino resin having a hydrophilic functional group in a molecule thereof. There is no need to leave hydrophilic groups in the molecular structure. Further, since it is an aqueous dispersion, the amino resin used can be used without being restricted by the solubility in water. That is, the type of amino resin can be appropriately selected and used in view of desired properties such as hardness and workability of the cured product. In addition, this amino resin aqueous dispersion is made of acrylic resin, epoxy resin, alkyd resin,
When used in water-based paints in combination with resins such as polyester resins, amino resin dispersions and other resins form submicron-order fine "sea-island structures" in cured coatings. It is expected. That such structures make a significant contribution to the mechanical properties is demonstrated by today's polymer alloy technology. In addition, the amino resin aqueous dispersion may be heated in the manufacturing process, and the oligomer or the oligomer resulting from the condensation of the amino resins, the amino resin and the hydroxyl group-containing acrylic monomer or acrylamide derivative, or the copolymerization thereof may be used. Condensation with the polymer is promoted, and the deformaldehyde reaction proceeds at this stage. Therefore, the amount of deformaldehyde after adaptation to various uses is reduced, which contributes to improvement of the working environment and the like.

Hereinafter, the present invention will be described in detail. The amino resin dispersion of the present invention is obtained by dispersing a substantially water-insoluble amino resin in water stably using the emulsifying ability of a hydrophilic acrylic resin. Therefore, hydrophilicity is not required for the amino resin used in the present invention. In fact, it is a well-known fact that making a highly hydrophilic dispersoid a stable aqueous dispersion is not as easy as dispersing a more hydrophobic dispersoid stably in water. The amino resin used in the present invention can be used irrespective of the presence or absence of hydrophilicity. However, those which can be mixed with water at an arbitrary ratio cannot be used. When such a dispersion is used, a dispersion cannot be obtained, and the dispersion becomes an aqueous solution, so that the above-mentioned excellent properties of the present amino resin dispersion cannot be exhibited.

As the amino resin used in the present invention, the condensation of an amino compound such as urea, melamine, benzoguanamine, acetoguanamine, spiroguanamine and an aldehyde such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, acrolein, etc. And / or their alkyl etherified compounds can be mentioned as examples. These can be used without particular limitation unless they are mixed with water at an arbitrary ratio. The method for denaturing urea, melamine, and guanamine is not particularly limited, and can be performed by a commonly used method. That is, by adding an appropriate amount of aldehydes at an appropriate reaction temperature under an acidic or alkaline reaction atmosphere and condensing with an amino resin,
An alkylolated amino resin can be obtained. The amount of the aldehyde to be added should be appropriately adjusted depending on the desired degree of alkylation of the alkylolated amino resin.
The appropriate alkylolation degree of the alkylolated modified amino resin that can be used in the present invention cannot be unconditionally determined depending on the type of the amino compound used, but the aldehyde of 0.1 equivalent or more per equivalent of active hydrogen contained in the amino compound is used. It may be preferable to react the compounds. If the alkylolation modification rate is too low, the thermosetting property characteristic of the amino resin may not be exhibited, which is not preferable. The amino resin modified with alkylolation can be converted into an alkyl etherified amino resin by further condensing with an alcohol. This modification can also be performed by a commonly used method. The alkyl etherification modification rate of the alkyl etherified amino resin that can be used in the present invention varies depending on the type of the amino compound used and the type of the alkyl etherifying agent, that is, the type of the alcohol, and cannot be determined unconditionally. Any material can be used without particular limitation as long as it does not mix with any ratio.

The above-mentioned amino resins and modified products thereof can be used alone or as a mixture of two or more. These amino resins are blended in an amount of 30 to 95% by weight based on the solid content of the obtained amino resin aqueous dispersion.
If the amount of the amino resin is less than 30% by weight, the ratio of the thermosetting component, that is, the amino resin in the obtained aqueous amino resin dispersion is reduced, which is not preferable in view of the gist of the present invention. Further, if the blending ratio of the amino resin is too low, the increase in viscosity derived from the acrylic resin as a polymer emulsifier described later becomes large, which is not preferable because it may hinder the properties of the obtained amino resin aqueous dispersion. . On the other hand, when the mixing ratio of the amino resin is more than 95% by weight, the ratio of the polymer emulsifier to the dispersoid becomes too low, so that it is difficult to obtain a stable amino resin aqueous dispersion.

The aqueous amino resin dispersion of the present invention comprises a radical polymerizable monomer having a carboxyl group or an amino group and a radical polymerizable monomer having a functional group capable of reacting with the amino resin. It is obtained by converting the radically polymerizable monomer into a resin by radical polymerization using a monomer as an essential component, neutralizing at least partially with an appropriate counter ion, and converting the monomer into an aqueous solution. The above-mentioned carboxyl group- or amino group-containing radical polymerizable monomer is used as an essential component in order to give an acrylic resin to be a polymer emulsifier to have an emulsifying ability in obtaining the amino resin aqueous dispersion of the present invention. The carboxyl group or amino group-containing radical polymerizable monomer,
0.1 to 21 in the solid content of the obtained amino resin aqueous dispersion
It is blended so as to be a weight%. If the amount is less than 0.1% by weight, sufficient emulsifying ability is not exhibited in the resinized acrylic resin, and a stable amino resin aqueous dispersion cannot be obtained. On the other hand, if the blending amount is more than 21% by weight, the ionicity of the acrylic polymer emulsifier to be produced becomes unnecessarily high, and the viscosity of the resulting amino resin aqueous dispersion may be too high, which is not preferable. Further, a thermosetting paint containing such an amino resin aqueous dispersion as a thermosetting component may be inferior in water resistance, transparency and the like, which is not preferable.

Examples of the carboxyl group-containing radically polymerizable monomer that can be used in the present invention include acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid, and fumaric acid. However, the present invention is not limited to this. These carboxyl group-containing radical polymerizable monomers can be used alone or as a mixture of two or more. Further, as the amino group-containing radical polymerizable monomer used in the present invention,
N, N-dimethylethylaminomethacrylate, N, N
-Diethylaminoethyl methacrylate and the like can be mentioned as examples, but are not limited thereto. These amino group-containing radically polymerizable monomers can be used as one kind or as a mixture of two or more kinds. In the present invention, a carboxyl group-containing radical polymerizable monomer and an amino group-containing radical polymerizable monomer cannot be used together. When the carboxyl group-containing radical polymerizable monomer is used as an essential component, the resulting amino resin aqueous dispersion becomes an anionic dispersion, and when the amino group-containing radical polymerizable monomer is used as an essential component, Becomes a cationic dispersion. Which radical polymerizable monomer is used as an essential component can be selected depending on the properties of the resin to be imparted with thermosetting properties using the present amino resin aqueous dispersion. That is, when the resin to be given thermosetting properties is an anionic aqueous resin, the former can be used, and when the resin is a cationic aqueous resin, the latter can be used.

In order to obtain the amino resin aqueous dispersion of the present invention, in addition to the above-mentioned carboxyl group or amino group-containing radically polymerizable monomer, a functional group capable of reacting with the amino resin in the molecule is required as an essential component. It is necessary to use a radical polymerizable monomer having the same. The above-described radical polymerizable monomer having a functional group capable of reacting with the amino resin is obtained by chemically bonding an amino resin as a dispersoid in the amino resin dispersion of the present invention and an acrylic resin as a polymer emulsifier. Which are indispensable for obtaining a stable amino resin aqueous dispersion. That is, the acrylic polymer emulsifier is bonded to the surface of the generated amino resin fine particles by the covalent bond formed by condensation of the functional group in the monomer and the amino resin, and the acrylic polymer emulsifier acts stably and effectively. It is blended in order to make it. Examples of the functional group capable of reacting with the amino resin include a hydroxyl group, an imino group, an N-methylol group, an N-alkyl etherified methylol group, and the like. It is not preferable to use a carboxyl group or an amino group for chemically bonding the amino resin and the acrylic polymer emulsifier, since it becomes difficult to control the properties of the dispersion to be obtained as described above. The above-mentioned radical polymerizable monomer having a functional group capable of reacting with the amino resin in the molecule is used in an amount of 0.15 to 21% by weight based on the solid content of the obtained amino resin aqueous dispersion. When the amount is less than 0.15% by weight, the above-mentioned stabilization and efficiency of the emulsification are not sufficiently performed, and it may be difficult to obtain a stable aqueous amino resin dispersion. Also,
If the compounding amount is more than 21% by weight, the bond between the amino resin and the polymer emulsifier becomes unnecessarily large, so that the viscosity of the system becomes too high at the time of the reaction, which hinders the operation and causes gelation. Sometimes it is not appropriate.

The radical polymerizable monomer having a functional group capable of reacting with an amino resin in the molecule which can be used in the present invention includes 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, Hydroxyl-containing radically polymerizable monomers such as 2-hydroxypropyl methacrylate,
Acrylamide, N-methylolacrylamide, N-
Methylol methacrylamide, N-methoxymethylacrylamide, N-ethoxymethylacrylamide, N-
An acrylamide derivative such as butoxymethylacrylamide can be exemplified, but not limited thereto. These monomers can be used alone or as a mixture of two or more.

The compound having an ethylenic α, β-unsaturated double bond in the molecule used in the present invention includes a carboxyl group or an amino group and an ethylenic α, β-unsaturated group in the molecule. Any compound can be used without particular limitation as long as it does not correspond to a compound having a saturated double bond or a compound having a functional group capable of reacting with an amino resin in the molecule and an ethylenic α, β-unsaturated double bond. Examples of such monomers include vinyl monomers such as styrene, vinyl toluene, methyl styrene, and vinyl acetate, methyl acrylate, ethyl acrylate, butyl acrylate, isopropyl acrylate, and the like.
Examples include (meth) acrylic monomers such as 2-ethylhexyl acrylate, 2-methoxyethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and glycidyl methacrylate. It is not limited. These monomers should be appropriately selected and used alone or as a mixture of a plurality of kinds in terms of physical properties of a cured product to be obtained.

The radically polymerizable monomers described above include:
In the presence of 30 to 95% by weight of the solid content of the amino resin, radical polymerization is carried out by a usual method to form a resin. That is, in the presence of a peroxide-based radical polymerization initiator, an azo-based radical polymerization initiator, or the like, radicals are generated by adding a reducing agent, heating, or the like, and the resinification reaction proceeds. The polymerization conditions are not particularly limited, but usually the polymerization temperature is 50 to 120.
C., the polymerization initiator is 0.1% based on the radical polymerizable monomers.
It is performed by adding about 1 to 10% by weight. In the polymerization, the radical polymerizable monomers may be previously mixed with the amino resin, or may be added dropwise to the amino resin little by little. The time required for resinification of the radical polymerizable monomer depends on the reaction time, but is usually about 1 to 8 hours. Further, in the resinification reaction, an organic solvent can be used in combination for adjusting the viscosity, controlling the reaction, and the like. If the organic solvent in the obtained amino resin aqueous dispersion is in an amount that does not hinder practical use, it can be used as it is without removal. When a resinification reaction is performed as an organic solvent solution, an amino resin aqueous dispersion can be obtained after removing the organic solvent as necessary. The method of removing the organic solvent used is not particularly limited, but the solvent is usually removed by heating. Moreover, you may carry out under reduced pressure as needed. At this time, the organic solvent may be removed as an azeotropic mixture by adding water. Therefore, in such a case, it is more preferable to use an organic solvent which is easier to remove the organic solvent, that is, an organic solvent having a relatively low boiling point. In the case where the organic solvent is removed, it is preferable that the solvent is removed after the neutralization described below.

When the resinification reaction is completed, the reactant composed of the amino resin and the acrylic resin becomes a uniform and transparent liquid or solution. This is considered to consist of a partial condensate of an amino resin and an acrylic resin. The amino resin aqueous dispersion of the present invention has a carboxyl group or an amino group in the amino resin-acrylic resin partial condensate, which is emulsified by converting the carboxyl group or amino group into a salt with a basic substance or an acidic substance, and then adding water. It is obtained by emulsification and dispersion. In the present invention, the basic substance to be neutralized with a carboxyl group to form a salt can be used without any particular limitation, but it is preferable to use a basic substance that can be easily volatilized in view of the water resistance of the cured product and the like. More preferred. Examples of the preferably used basic substance include, but are not limited to, ammonia, ethylamine, diethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, dimethylaminoethanol, cyclohexylamine and the like. Further, in the present invention, an acidic substance to be neutralized to form a salt by neutralizing an amino group can be used without any particular limitation, but it is more preferable to use an acidic substance that can be easily volatilized in view of the water resistance of the cured product. preferable. Examples of the acidic substance preferably used include, but are not limited to, formic acid and acetic acid. Although the degree of neutralization of the amino resin-acrylic resin partial condensate is not particularly limited, it is usually more preferable to carry out neutralization of 80 mol% or more. The amino resin-acrylic resin partial condensate neutralized product thus obtained is emulsified by adding water and stirring to obtain an amino resin aqueous dispersion. The amount of water to be added is not particularly limited as long as the amino resin-acrylic resin partial condensate neutralized product can be dispersed in an oil-in-water type, but in view of the desired solid content of the amino resin aqueous dispersion. It can be appropriately selected. In order to obtain a practical amino resin aqueous dispersion, a solid content of 1
It is desirable to add an amount of water so as to be 0 to 60% by weight.

Further, the curable aqueous coating composition of the present invention contains the solid content of the amino resin aqueous dispersion of the present invention in the resin solid content of 5%.
It can be obtained by incorporating at least% by weight. If the solid content of the amino resin aqueous dispersion in the solid content of the curable aqueous coating composition is less than 5% by weight, sufficient thermosetting properties cannot be imparted to the aqueous coating composition, and the water resistance of the obtained cured product, etc. Is not preferred because Although the aqueous amino resin dispersion of the present invention can be used as a curable aqueous coating even by using the aqueous amino resin dispersion alone, other aqueous resin components can be contained if necessary. The resin component that can be added is not particularly limited as long as it does not destroy the dispersion structure of the amino resin aqueous dispersion, and examples thereof include aqueous acrylic resins, aqueous epoxy resins, aqueous polyester resins, and aqueous urethane resins. Can be added. These resins can be added as a water-soluble resin or an aqueous dispersion. Usually, these resins are partially water-soluble or water-dispersed by imparting partial ionicity in the molecule, but for use in the present curable water-based paint, the amino resin contained as an essential component in the paint is used. It is necessary to use in consideration of the ionicity of the aqueous dispersion. That is, when a cationic aqueous resin is added to an aqueous anionic amino resin dispersion, an aqueous resin having the same polarity as that of the amino resin aqueous dispersion is used, since aggregation / sedimentation or gelation may occur. Is preferred. Also,
The curable water-based paint may contain, as necessary, dyes and pigments for coloring and the like, and various additives for improving the properties of the cured product, such as fillers, leveling agents, defoamers, curing agents, flame retardants, It may contain a thickener, a water-soluble organic solvent, a lubricity-imparting agent, and the like. The curable water-based paint of the present invention comprises a metal,
It can be used as a base material for wood, glass, concrete, building materials, etc., at a temperature of 120 to 250 ° C. for 30 seconds to 1
Baking can be performed for about 0 minutes.

[0019]

EXAMPLES The present invention will be described below in more detail with reference to examples, but these examples do not limit the present invention in any way. In the following examples and comparative examples, “parts” means parts by weight unless otherwise specified. Example 1 A reaction vessel equipped with a stirrer was charged with 3000 parts of n-butanol, 3000 parts of benzoguanamine, and 3600 parts of a formaldehyde 40% n-butanol solution (formit NB manufactured by Koei Chemical Co., Ltd.).
H was adjusted to 6 and the reaction was carried out at 100 ° C. for about 1 hour. Thereafter, 50 parts of xylene was added, and azeotropic dehydration was performed for about 3 hours to remove water. After maintaining the temperature of the reaction solution at 80 ° C. and replacing the inside of the reaction vessel with nitrogen, 400 parts of styrene, 170 parts of butyl acrylate, 80 parts of acrylic acid, 150 parts of 2-hydroxyethyl methacrylate and azobisisobutyronitrile were added through a dropping tube. 30 parts of the mixture were added dropwise in about 2 hours.
After the completion of the dropwise addition, 10 parts of azobisisobutyronitrile were added three times every two hours, and the reaction was continued at the same temperature for another two hours. A mixture of 100 parts of N, N-dimethylaminoethanol and 100 parts of ion-exchanged water was gradually added and stirred so as to be uniform, and 6000 parts of ion-exchanged water was gradually added while sufficiently stirring. Thereafter, the liquid temperature was raised to 93 ° C., and 1500 parts of n-butanol were distilled off to obtain a milky white amino resin aqueous dispersion (a) having a nonvolatile content of about 60% by weight. When the particle diameter was measured by a laser scattering method, the average particle diameter was about 150.
nm. When this was stored at 50 ° C. for about one month, neither separation nor aggregate was observed.

Example 2 3400 parts of a butyl etherified benzoguanamine resin (Cymel 1128 70% n-butanol solution manufactured by Mitsui Cyanamid Co., Ltd.) was placed in a reaction vessel equipped with a stirrer, the temperature was raised to about 80 ° C., and the inside of the reaction vessel was cooled. After purging with nitrogen, 184 parts of styrene, 428 parts of ethyl acrylate, 153 parts of 2-ethylhexyl acrylate, 20 parts of N-methoxymethylacrylamide were added through a dropping tube.
A mixture of 4 parts, 51 parts of methacrylic acid and 31 parts of t-butyl peroxide was added dropwise in about 2 hours. One hour after the completion of the dropwise addition, 10 parts of t-butyl peroxide was added, and the reaction was further continued for 1 hour, and a mixture of 90 parts of triethanolamine and 90 parts of ion-exchanged water was gradually added. Further, 5000 parts of ion-exchanged water was gradually dropped while sufficiently stirring, and the temperature of the solution was raised to 93 ° C. to make 100 parts of n-butanol.
Zero parts were distilled off, and the mixture was diluted with ion-exchanged water so as to have a non-volatile content of about 40% to obtain a milky white amino resin aqueous dispersion (b). When the particle size was measured by a laser scattering method, the average particle size was about 200 nm. When this was stored at 50 ° C. for about one month, neither separation nor aggregate was observed.

Example 3 A reaction vessel equipped with a stirrer was charged with 2250 parts of butyl etherified melamine (Cymel 1156 manufactured by Mitsui Cyanamid Co.) and heated to 80 ° C. to replace the inside of the reaction vessel with nitrogen. From a dropping tube, 255 parts of methyl methacrylate, 75 parts of butyl methacrylate, 150 parts of butyl acrylate, 120 parts of N-methoxymethylacrylamide, and 150 parts of dimethylaminoethyl methacrylate
Parts and 45 parts of t-butyl peroxide in about 2 parts.
Dropped in time. After completion of the dropwise addition, 4.5 parts of t-butyl peroxide was added twice every one hour, and the reaction was continued for another hour, and the liquid temperature was lowered to 50 ° C. A mixture of 57 parts of acetic acid and 57 parts of ion-exchanged water was gradually added thereto, and 3000 parts of ion-exchanged water was gradually added dropwise with sufficient stirring to obtain a milky white aqueous amino resin dispersion having a nonvolatile content of about 50% ( c) was obtained. When the particle size was measured by a laser scattering method, the average particle size was about 185 nm. When this was stored at 50 ° C. for about one month, separation,
No aggregates were observed.

Example 4 1440 parts of butyl etherified melamine (Cymel 1156 manufactured by Mitsui Cyanamid Co., Ltd.) was placed in a reaction vessel equipped with a stirrer, heated to 80 ° C., and the inside of the reaction vessel was purged with nitrogen. 432 parts of butyl acrylate, 216 parts of 2-ethylhexyl acrylate from the dropping tube,
A mixture of 259 parts of N-methoxymethylacrylamide, 389 parts of dimethylaminoethyl methacrylate and 130 parts of t-butyl peroxide was added dropwise in about 2 hours.
Every hour after the completion of dropping, t-butyl peroxide 2
6 parts were added twice, and the reaction was further continued for 1 hour.
Reduced to 0 ° C. A mixture of 57 parts of acetic acid and 57 parts of ion-exchanged water is gradually added thereto, and 2400 parts of ion-exchanged water is gradually added dropwise with sufficient stirring to obtain an aqueous dispersion of an amino resin having a milky white viscous nonvolatile content of about 60%. A body (d) was obtained. When the particle size was measured by the laser scattering method,
The average particle size was about 160 nm. When this was stored at 50 ° C. for about one month, neither separation nor aggregate was observed.

Example 5 400 parts of an acrylic resin aqueous dispersion (Sanpearl PS-2, 39% non-volatile content, manufactured by Sanyo Chemical Co., Ltd.), 400 parts, hydroxyethyl cellulose were added to 600 parts of the amino resin aqueous dispersion (a) prepared in Example 1. 10
Parts and 2 parts of phosphoric acid were added and mixed well to obtain a curable aqueous resin composition (A).

Example 6 350 parts of the aqueous amino resin dispersion (b) prepared in Example 2 was mixed with 350 parts of an aqueous acrylic resin dispersion (Tokuril BCX-10 manufactured by Toyo Ink Mfg. Co., Ltd.).
07 nonvolatile content 40%) 210 parts, epoxy resin aqueous dispersion (Toato Kasei Co., Ltd. Aquato 3520 nonvolatile content 55%) 100 parts, titanium oxide 120 parts and phosphoric acid 1.
5 parts were added and sufficiently stirred and dispersed to obtain a curable aqueous resin composition (B).

Example 7 500 parts of the aqueous amino resin dispersion (c) prepared in Example 3 was mixed with an aqueous acrylic resin dispersion (Tokuril BCX-81 manufactured by Toyo Ink Mfg. Co., Ltd.).
93 non-volatile components 40%), 300 parts of an epoxy resin aqueous dispersion (Aquato 3520 manufactured by Toto Kasei Co., Ltd.) and 2 parts of sodium p-toluenesulfonate were added.
The mixture was sufficiently mixed to obtain a curable aqueous resin composition (C).

Comparative Example 1 A reaction vessel equipped with a stirrer was charged with 3400 parts of a butyl etherified benzoguanamine resin (70% n-butanol solution of Cymel 1128 manufactured by Mitsui Cyanamid Co., Ltd.), and the temperature was raised to about 80 ° C. After purging with nitrogen, a mixture of 208 parts of styrene, 508 parts of ethyl acrylate, 153 parts of 2-ethylhexyl acrylate, 151 parts of methacrylic acid and 31 parts of t-butyl peroxide was dropped from the dropping tube in about 2 hours. One hour after the completion of the dropwise addition, 10 parts of t-butyl peroxide was added, and the reaction was further continued for 1 hour, and a mixture of 90 parts of triethanolamine and 90 parts of ion-exchanged water was gradually added. Further, while sufficiently stirring, deionized water 5000
The liquid temperature was raised to 93 ° C., 1000 parts of n-butanol was distilled off, and the mixture was diluted with ion-exchanged water so as to have a nonvolatile content of about 40%. A resin aqueous dispersion (e) was obtained. When the particle size was measured by a laser scattering method, the average particle size was about 1200 n.
m. When this was allowed to stand at room temperature for about 2 days, it was separated into two layers.

Comparative Example 2 In a reaction vessel equipped with a stirrer, 2250 parts of butyl etherified melamine (Cymel 1156 manufactured by Mitsui Cyanamid Co., Ltd.) was placed, heated to 80 ° C., and the inside of the reaction vessel was purged with nitrogen. From a dropping tube, a mixture of 335 parts of methyl methacrylate, 100 parts of butyl methacrylate, 195 parts of butyl acrylate, 120 parts of N-methoxymethylacrylamide and 45 parts of t-butyl peroxide was dropped in about 2 hours. T- every other hour after completion of dropping
4.5 parts of butyl peroxide were added twice and one more part was added.
The reaction was continued for an hour, and the liquid temperature was lowered to 50 ° C. A mixture of 57 parts of acetic acid and 57 parts of ion-exchanged water is gradually added thereto,
Further, 3000 parts of ion-exchanged water was gradually dropped while sufficiently stirring, but it could not be emulsified and separated.

Comparative Example 3 In a reaction vessel equipped with a stirrer,
Butyl etherified melamine (Mitsui Cyanamid)
1200 parts of Cymel 1156) was added and heated to 80 ° C., and the inside of the reaction vessel was purged with nitrogen. From a dropping tube, a mixture of 400 parts of methyl methacrylate, 200 parts of butyl methacrylate, 300 parts of butyl acrylate, 150 parts of 2-hydroxyethyl methacrylate, 750 parts of methacrylic acid and 54 parts of t-butyl peroxide was dropped in about 2 hours.
One hour after the completion of the dropping, t-butyl peroxide 5
The mixture was added twice, and the reaction was continued for another 1 hour.

[Comparative Example 4] Acrylic resin aqueous dispersion (SANSPEARL PS-2 manufactured by Sanyo Kasei Co., Ltd.) 315 was added to 30 parts of the aqueous amino resin dispersion (b) prepared in Example 2.
Parts, 255 parts of an epoxy resin aqueous dispersion (Aquatoto 3520 manufactured by Toto Kasei Co., Ltd.), 120 parts of titanium oxide and 1.5 parts of phosphoric acid, and sufficiently stirred and dispersed to obtain an aqueous resin composition (D). .

[Comparative Example 5] A benzoguanamine derivative resin (Cymel 1125 manufactured by Mitsui Cyanamid Co., Ltd.) was added to 30 parts of the amino resin aqueous dispersion (b) prepared in Example 2.
-80) 235 parts, aqueous acrylic resin dispersion (SANSPEARL PS-2, manufactured by Sanyo Chemicals) 200 parts, aqueous epoxy resin dispersion (Aquatoto 3520, manufactured by Toto Kasei) 2
20 parts and 8 parts of phosphoric acid were added, and the mixture was sufficiently stirred and dispersed to obtain an aqueous resin composition (E).

The aqueous resin compositions obtained in Examples 5 to 7 and Comparative Examples 4 and 5 were applied to a galvanized steel sheet using a bar coater so that the dry coating thickness became 10 μm.
Heat treatment was performed at 00 ° C. for 10 minutes. Table 1 summarizes the physical property evaluation results of the test pieces thus obtained and the storage stability of the aqueous resin composition. In the impact resistance test, after a DuPont impact test was performed, a Gobang cellophane tape peeling test was performed, and among 100 squares of 1 × 1 mm, the number of squares remaining without peeling was indicated. The water resistance test was performed in boiling water for 3 hours.
Immerse for 0 minutes, conduct a Gobang-scotch tape peeling test, 1 ×
The number of squares remaining without peeling out of 100 squares of 1 mm was indicated.

[0032]

[Table 1]

[0033]

According to the present invention, an amino resin widely used as a thermosetting component can be used in an aqueous system with a wide degree of freedom. Further, according to the present invention, it is possible to impart water resistance of hardness and mechanical properties to the cured product.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09D 155/00 C09D 155/00 (72) Inventor Tadashi Nakamura 2-3-1 Kyobashi, Chuo-ku, Tokyo Toyo Ink Manufacturing Co., Ltd. Examiner Yumiko Isshiki (56) References JP-A-5-132647 (JP, A) JP-B-48-20789 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 51 / 08 C08F 283/00 C08F 299/02 C08L 55/00 C09D 151/08 C09D 155/00

Claims (4)

(57) [Claims] 1. A substantially water-insoluble amino resin 56.9.
0.1 to 21 % by weight of a compound having a carboxyl group and an ethylenic α, β-unsaturated double bond in the molecule in the presence of ８９89.6% by weight, a functional group capable of reacting with an amino resin in the molecule, and 0.15 to 21% by weight of a compound having an ethylenic α, β-unsaturated double bond as an essential component, and at least one kind of a compound having an ethylenic α, β-unsaturated double bond in another molecule Together with radical polymerization and at least partially neutralized by a basic substance,
Aqueous amino resin dispersion obtained by making aqueous. 2. A substantially water-insoluble amino resin 30-9.
0.1 to 21% by weight of a compound having an amino group and an ethylenic α, β-unsaturated double bond in the molecule in the presence of 5% by weight, a functional group capable of reacting with the amino resin and an ethylenic α in the molecule Compound having β, unsaturated double bond 0.1
Radical polymerization of 5 to 21% by weight as an essential component together with at least one or more other compounds having an ethylenic α, β-unsaturated double bond in the molecule, and after at least partially neutralizing with an acidic substance , An aqueous amino resin dispersion obtained by aqueous conversion. 3. A curable aqueous coating composition comprising, as an essential component, at least 5% by weight of the solid content of the amino resin aqueous dispersion according to claim 1 in the resin solid content. 4. A curable aqueous coating composition comprising, as an essential component, at least 5% by weight of the solid content of the amino resin aqueous dispersion according to claim 2 in the resin solid content.