JP2002146281A - Water-based one-pack coating agent and coating method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-based one-pack coating agent which excels in storage stability, is safe in consideration of the environment, exhibits adhesion to a base material in a short period of time, and has good external appearance of films, and to provide a coating method having excellent workability. SOLUTION: The water-based one-pack coating agent comprises a one-pack thermosetting resin emulsion which is obtained by dispersing an organic polyisocyanate in water to effect the reaction between the isocyanate and the water until any free isocyanate group substantially ceases to be present and substantially has no free isocyanate group. The coating method comprises coating this coating agent on a base material at <100 deg.C and then thermosetting the resulting film at 100-300 deg.C. Further, the above organic polyisocyanate is preferably a self-emulsifiable polyisocyanate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aqueous one-pack coating agent and a coating method using the same.

[0002]

2. Description of the Related Art Coating agents containing a large amount of organic solvents have adverse effects on human health, safety and health problems such as explosion and fire,
In addition, it has pollution problems such as air pollution. Therefore, in order to improve these problems, aqueous systems have been actively developed in recent years. On the other hand, urethane-based coating agents
Shows good adhesion to various substrates. Therefore, a conventional aqueous urethane-based coating agent is a two-pack type consisting of (a) a main agent having an active hydrogen group and a polyisocyanate curing agent, and (b) a main agent having an active hydrogen group, in which a blocked isocyanate is previously blended. One-pack type,
(C) One-pack type composed of a resin having an isocyanate group.

[0003] The type (a) is disclosed in
No. 1016 discloses a water-based coating agent using a specific water-based acrylic resin as a main component and a water-dispersible polyisocyanate composition as a curing agent. (B) As the type, Japanese Patent Application Laid-Open No. 8-4891
No. 3 discloses an aqueous coating agent in which a specific hydrophobic polymer is dispersed in water with a surfactant as a main agent, and an aqueous coating agent using a blocked isocyanate as a curing agent. (C) As the type, Japanese Patent Laid-Open No. 7-48
No. 429, which discloses a coating agent using a self-emulsifiable polyisocyanate dispersed in water.

[0004] However, the coating agent of the type (a) must be blended with the base resin and the curing agent immediately before use. Further, after blending the main agent and the curing agent, it must be used up immediately and it is very difficult to store the blended once. In the case of the type (b), there is a problem that the blocking agent that has not been dissociated during curing gradually dissociates, such as a decrease in adhesion. The (c) type has a problem due to carbon dioxide gas generated at the time of reaction between water and an isocyanate group (damage of a container during storage, poor state of a film), and the like.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to an aqueous one-part composition which has excellent storage stability, is safe in consideration of the environment, exhibits adhesion to a substrate in a short time, and has a good film appearance. An object of the present invention is to provide a coating agent and a coating method excellent in workability.

As a result of intensive studies, the present inventors have found that an aqueous one-part coating agent using a specific aqueous dispersion solves the above-mentioned problems, and have completed the present invention.

That is, the present invention is obtained by dispersing an organic polyisocyanate in water and reacting isocyanate groups with water until substantially no free isocyanate groups are present, and is substantially free of free isocyanate groups. An aqueous one-pack coating agent comprising a one-pack thermosetting resin emulsion.

[0008] The present invention is also an aqueous one-pack coating agent, wherein the organic polyisocyanate is a self-emulsifying polyisocyanate.

Further, the present invention provides a method for applying the aqueous one-pack coating agent to a substrate at a temperature lower than 100 ° C.
This is a coating method of thermosetting at 00 ° C.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The aqueous one-pack coating agent of the present invention is obtained by dispersing an organic polyisocyanate in water and reacting isocyanate groups with water until substantially no free isocyanate groups are present, and substantially free isocyanate groups are obtained. It is characterized by containing a one-component thermosetting resin emulsion that does not have it. The term "one-component thermosetting" means that the composition is cured by heating alone without using a curing agent or a crosslinking agent. Further, “curing” means that when a film is formed, it becomes a film having at least solvent resistance.

[0011] The isocyanate content of the organic polyisocyanate used in the present invention is preferably 1 to 30% by mass, particularly preferably 1 to 25% by mass. Further, the viscosity at 25 ° C. is preferably 5,000 mPa · s or less, particularly preferably 4,500 mPa · s or less. The average number of functional groups is preferably from 2 to 5, particularly preferably from 2 to 4.

The organic polyisocyanate is obtained by reacting an isocyanate compound, an isocyanate compound with an active hydrogen group-containing compound such as water, a polycarboxylic acid, a polyol, a polyamine, or an aminoalcohol to form urea, urethanate, or amidate. Isocyanate group-containing modified product, or dimerization of an isocyanate group simultaneously with, before, or after the reaction (uretdione bond,
Isocyanate group-containing modified products obtained by performing carbodiimide bond formation), trimerization (formation of isocyanurate bond), high polymerization (formation of uretonimine bond, etc.), and the like. Tolylene diisocyanate, 2,6-tolylene diisocyanate, xylene-
1,4-diisocyanate, xylene-1,3-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate,
4,4'-diphenyl ether diisocyanate, 2-
Nitrodiphenyl-4,4'-diisocyanate, 2,
2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-
Diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-
Aromatic diisocyanates such as phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, polyphenylenepolymethylene polyisocyanate, crude tolylene diisocyanate, etc. Aromatic polyisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, aliphatic diisocyanate such as hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethyl xylene diisocyanate, etc. An alicyclic diisocyanate, Let modified compounds, uretdione modified product, a carbodiimide modified product, an isocyanurate modified product,
Modified polyisocyanates such as uretonimine modified products and mixed modified products thereof are exemplified.

An isocyanate group-terminated prepolymer obtained by reacting the above-mentioned polyisocyanate with an active hydrogen group-containing compound. This prepolymer is further modified by biuret modification, uretdione modification, carbodiimide modification, isocyanurate modification, uretonimine modification, or a mixture thereof. The polyisocyanate obtained by the above can also be suitably used.

Examples of the active hydrogen group-containing compound include water, low molecular weight polyols having a (number average) molecular weight of 62 to less than 500, low molecular weight polyamines, low molecular weight amino alcohols, and high molecular weight compounds having a number average molecular weight of 500 to 10,000. And molecular polyols. These active hydrogen group-containing compounds can be used alone or in combination of two or more.

Examples of the low molecular polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5 -Pentanediol, 1,6-hexanediol, 2-methyl-1,
5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, decamethylene glycol, diethylene glycol, dipropylene glycol, 2,2-diethyl- 1,3-propanediol, 2
-N-butyl-2-ethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-n-
Hexadecane-1,2-ethylene glycol, 2-n-
Eicosan-1,2-ethylene glycol, 2-n-octacosan-1,2-ethylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, 3-hydroxy-2,2-dimethylpropyl- 3-hydroxy-2,2-dimethylpropionate, dimer acid diol, bisphenol A, hydrogenated bisphenol A, ethylene oxide or propylene oxide adduct of bisphenol A, ethylene oxide or propylene oxide adduct of hydrogenated bisphenol A, tri Low molecular weight polyols having no ionic group, such as methylolpropane, glycerin, hexanetriol, quadrol, pentaerythritol, sorbitol, 2,2-dimethylolpropionic acid, 2,
-COOH-containing low-molecular-weight polyols such as 2-dimethylolbutanoic acid; salts of -COOH-containing low-molecular-weight polyols with ammonia, organic amines, alkali metals, alkaline earth metals, and the like; 2-sulfo-1,3-propane Diol, 2
Low-molecular-weight polyols containing a sulfonic acid group such as -sulfo-1,4-butanediol, and salts of the low-molecular-weight polyols containing a sulfonic acid group with ammonia, organic amines, alkali metals, alkaline earth metals, and the like.

As the low molecular weight polyamine, ethylenediamine, hexamethylenediamine, isophoronediamine,
Mensendiamine, 4,4′-diphenylmethanediamine, 4,4′-diaminodiphenylsulfone, metaxylenediamine, piperazine and the like.

Examples of the low molecular weight amino alcohol include monoalkanolamines such as monoethanolamine, monopropanolamine, diethanolamine and dipropanolamine, and dialkanolamines.

Examples of the high molecular polyol include polyester polyol, polyamide ester polyol, polycarbonate polyol, polyether polyol, polyether ester polyol, polyolefin polyol, plant and animal polyol, and the like.

The polyester polyols include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, curtaconic acid, azelaic acid, sebacic acid, succinic acid, Adipic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α,
Polycarboxylic acids having no cationic group such as β-diethylsuccinic acid, maleic acid, fumaric acid, trimellitic acid, and pyromellitic acid; sulfonic acid group-containing polycarboxylic acids such as 5-sulfo-isophthalic acid; Reaction of at least one kind of salts of acid group-containing polycarboxylic acid with ammonia, organic amine, alkali metal, alkaline earth metal, etc., their acid anhydrides, acid halides, dialkyl esters, etc., and the aforementioned low molecular polyols And the like obtained by the above method. Further, ε-caprolactone, alkyl-substituted ε-
Caprolactone, δ-valerolactone, alkyl-substituted δ
And lactone-based polyester polyols obtained by ring-opening polymerization of cyclic ester (so-called lactone) monomers such as valerolactone. Further, polyamide ester polyols obtained by using low molecular weight polyamines such as hexamethylene diamine, isophorone diamine, monoethanolamine or low molecular weight amino alcohols instead of a part of the low molecular weight polyols may be mentioned.

Examples of the polycarbonate polyol include those obtained by a dealcoholation reaction or a dephenolization reaction of at least one of the above-mentioned low molecular polyols with ethylene carbonate, diethyl carbonate and diphenyl carbonate.

As the polyether polyol, the above-mentioned low molecular polyol, low molecular polyamine or low molecular amino alcohol is used as an initiator to open a ring or a mixture of alkyl ether oxides such as ethylene oxide and propylene oxide and cyclic ethers such as tetrahydrofuran. Examples thereof include those obtained by polymerization.

Examples of the polyetherester polyol include a copolyol obtained from the above-mentioned polyether polyol and the above-mentioned dicarboxylic acid and the like. Also,
Those obtained by the reaction of the above-mentioned polyester or polycarbonate with an alkylene oxide or a cyclic ether are exemplified.

Examples of the polyolefin polyol include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, hydrogenated polyisoprene, and chlorinated products thereof.

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

If the number-average molecular weight is 500 or more and one molecule has an average of at least one active hydrogen group in one molecule, an epoxy resin may be used in addition to the dimer acid polyol and the hydrogenated dimer acid polyol. , Polyamide resin,
Active hydrogen group-containing resins such as polyester resin, acrylic resin, rosin resin, urea resin, melamine resin, phenol resin, coumarone resin, and polyvinyl alcohol can also be used.

The temperature in the reaction between the isocyanate group and the active hydrogen group is preferably from 0 to 100 ° C., more preferably from 20 to 100 ° C.
80 ° C. is preferred. Further, the molar ratio of the isocyanate group to the active hydrogen group at this time is preferably isocyanate group / active hydrogen group = 1.1 / 1 to 2/1.

The reaction apparatus at this time may be any apparatus as long as the above reaction can be achieved, and examples thereof include a mixing and kneading apparatus such as a reaction vessel equipped with a stirrer, a kneader, and a single-screw or multi-screw extrusion reactor. In order to accelerate the reaction, a metal catalyst such as dibutyltin dilaurate or a tertiary amine catalyst such as triethylamine which is commonly used in the production of polyurethane or polyurea may be used as a catalyst.

In the present invention, a preferable organic polyisocyanate is an isocyanurate / urethane-modified polyisocyanate from the viewpoint of adhesion and durability of the coating. A polyisocyanate having no self-emulsifying property can be used because a one-part thermosetting resin emulsion can be produced by using a surfactant at the time of dispersing in water and reacting isocyanate groups with water. . In this case, the amount of the surfactant is 1 to 2 with respect to the non-self-emulsifying polyisocyanate.
The amount which becomes 0 mass% is preferable. In addition, "self-emulsifying property" means that it has a property of dispersing in water by itself without using a surfactant or an emulsifier.

In the present invention, a self-emulsifying polyisocyanate which does not require a surfactant is preferred. This is because the surfactant may bleed from the coating, which may result in poor appearance or reduced coating strength.

Further, a particularly preferred organic polyisocyanate is an isocyanurate / urethane-modified polyisocyanate modified with a compound having a hydrophilic polar group and an active hydrogen group (hydrophilic modifier) in view of adhesion and durability of the coating. It is a self-emulsifying polyisocyanate obtained by the reaction.

The hydrophilic polar group in the hydrophilic modifier may be any of a cationic hydrophilic polar group, an anionic hydrophilic polar group, and a nonionic hydrophilic polar group. Considering the properties and the like, a nonionic hydrophilic polar group is preferred. A particularly preferred modifier is obtained by ring-opening addition of an alkylene oxide using a monool having 1 to 10 carbon atoms as an initiator, contains 50% by mass or more of oxyethylene groups, and has a number average molecular weight of 200 to 10%. 2,000, which is a polyether monol.

In the self-emulsifying polyisocyanate, the content of the nonionic modifier is 0.1 to 10% by mass.
Is preferable, and 0.5 to 8% by mass is particularly preferable. This is because when the amount of the nonionic modifier is too large, the mechanical strength and durability of the coating tend to be insufficient. If the amount is too small, the resulting polyisocyanate tends to be less likely to self-emulsify.

The self-emulsifiable polyisocyanate can be reacted with a hydrophobic and monofunctional active hydrogen group-containing compound in consideration of the adhesion of the film. Examples of the active hydrogen group-containing compound include methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, t-butanol, pentanol, hexanol, heptanol, octanol, 2-ethylhexanol, benzyl alcohol, Low molecular weight monools such as cyclohexanol and alkylene glycol monoalkyl ether; low molecular weight primary monoamines such as ethylamine, butylamine and aniline; low molecular weight secondary monoamines such as diethylamine, dibutylamine and methylaniline; active hydrogen group-containing C6 or more carbon atoms such as polyester, active hydrogen group-containing polyether having less than 50 mol% of ethylene oxide units, active hydrogen group-containing polycarbonate, active hydrogen group-containing polyolefin, ricinoleic acid, etc. Include hydroxy higher fatty acid or its esters and the like.

In the present invention, a preferable organic polyisocyanate is an isocyanurate-urethane-modified polyisocyanate (urethanization and isocyanate) obtained from hexamethylene diisocyanate and a low molecular weight polyol in consideration of the weather resistance, heat resistance, adhesion and the like of the film. Nuration may be simultaneous or sequential), and a number-average molecular weight of 300 to 2,000 obtained using a monool having 1 to 5 carbon atoms as an initiator.
It is a self-emulsifying polyisocyanate obtained by reacting 0 (particularly preferably 350 to 800) alkoxy polyethylene glycol.

Next, a specific process for producing a coating agent will be described. First, water and an organic polyisocyanate are charged into a reactor equipped with a stirrer, and the mixture is stirred and emulsified and dispersed. It is important that the reactor is not sealed. If a closed reactor is used, the internal pressure increases due to the generated carbon dioxide gas, and the reactor itself may be damaged. When the organic polyisocyanate used is non-self-emulsifying, it is emulsified and dispersed in water using a surfactant. From the middle of the dispersion, the reaction between the isocyanate group and water gradually progresses. At this time, it is important that stirring is not stopped. This is because, when the stirring is stopped, the particles are aggregated, so that a uniform dispersion is not obtained. The average particle size of the particles in the dispersion is the stirring speed, the amount and type of hydrophilic polar group introduced when using a self-emulsifying polyisocyanate, and the surfactant when using a non-self-emulsifying polyisocyanate. It can be controlled by the introduction amount and type. Note that the stirring speed is preferably 200 times or more per minute. The end of the reaction is where the isocyanate groups no longer remain. The reaction temperature at this time is preferably from 0 to 100 ° C, particularly preferably from 10 to 80 ° C. Further, the solid content in the reaction system is preferably set to 10 to 90% by mass, particularly preferably 20 to 80% by mass.

The one-part thermosetting resin emulsion thus obtained has an average particle diameter of preferably 10 to 1,000 nm, particularly preferably 20 to 500 nm. If the average particle size is too small, an emulsion may not be formed and the viscosity may increase. If the average particle size is too large, the particles may settle with time. The average particle size in the present invention is a value obtained by analyzing a value measured by a dynamic light scattering method by a cumulant method.

In the present invention, the above-mentioned emulsion and another resin-based emulsion can be blended and used. For example, polyurethane emulsion, acrylic emulsion, polyester emulsion, polyolefin emulsion, vinyl acetate emulsion, polyvinyl chloride emulsion, ethylene-vinyl acetate emulsion, vinylidene chloride emulsion, latex and the like.

[0038] Additives and auxiliaries can be added to the obtained emulsion, if necessary. As additives and auxiliaries, pigments, dyes, viscosity modifiers, leveling agents, anti-gelling agents, light stabilizers, antioxidants, ultraviolet absorbers, heat resistance improvers, inorganic and organic fillers, plasticizers, Lubricants, antistatic agents, reinforcing materials, catalysts, thixotropic agents, surfactants,
Emulsifiers and the like are mentioned.

The aqueous one-pack coating agent thus obtained has substantially no free isocyanate groups. When substantially free isocyanate groups are present, the resulting coating may have "bloated", "foam",
"Peeling" or the like occurs, and the appearance is likely to be poor. In addition, since carbon dioxide is generated by the reaction between the isocyanate group and water during storage, the internal pressure of the container increases, and the container is easily damaged.

Next, a specific coating procedure will be described. The temperature at which the coating agent is applied to the substrate is preferably less than 100 ° C., preferably room temperature, in order to prevent dripping and rapid evaporation of water. The coating amount of the coating agent is 1 to 100 g / m ² , preferably ^{2 to} 80 g in terms of solid content of 100% by mass.
g / m ² . As a coating method, a known method such as a brush, a bar coater, a doctor blade, a reverse roll, a gravure roll, a spinner coat, and an extruder is used.

The substrate in the coating method of the present invention is required to have heat resistance since it is heated after the application of the coating agent. The optimal substrate for the coating method of the present invention is a metal-based substrate.

After the coating agent is applied, 100 to 3
The composition is cured by heating at 00 ° C, preferably at 120 to 280 ° C. The heating time is preferably from 30 seconds to 120 minutes, particularly preferably from 5 to 60 minutes. Since the present invention can obtain a film excellent in physical properties in a short time,
Heating times that are too long not only wastes energy, but also imparts unnecessary heat history to the coating. In addition,
Before heat curing, it is preferable to evaporate water at a temperature of less than 100 ° C., preferably 80 ° C. or less for 5 to 60 minutes.

In the present invention, the curing mechanism of the aqueous one-part coating agent is unknown, but for example, between the amino group and the urethane group, between the amino group and the urea group, between the urea groups, between the urethane groups, between the urethane groups and the urea group. Is considered to have been cured by the exchange reaction of

In the coating method of the present invention, since the aqueous one-part coating agent containing the one-part thermosetting resin emulsion having substantially no isocyanate group is used alone, it is compared with the two-part type aqueous coating agent. Thus, there is an advantage that workability is good.

[0045]

The present invention will be described in detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. In addition,
In the following examples, "%" means% by mass, unless otherwise specified.

[Production of Self-Emulsifying Polyisocyanate] Production Example 1 Capacity with Stirrer, Thermometer, Nitrogen Seal Tube, Cooler:
After the inside of a 500 ml reactor was replaced with nitrogen, 300 g of hexamethylene diisocyanate (HDI) and 2.4 g of 1,3-butanediol (1,3-BD) were charged, and urethanation was performed at 80 ° C. for 2 hours with stirring. Reacted. When the isocyanate content of the reaction solution was measured, it was 48.8%
Met. Next, as a catalyst, potassium caprate 0.0
6 g and 0.3 g of phenol as a co-catalyst were added.
Was carried out for 4.5 hours. 0.042 g of phosphoric acid was added to this reaction solution as a terminator,
After stirring for 1 hour at room temperature, free HDI was thin-film distilled (conditions: 120
C., 1.3 Pa). The obtained isocyanurate-urethane-modified polyisocyanate is a pale yellow transparent liquid, isocyanate content: 21.1%, viscosity at 25 ° C .: 2,200 mPa, free HDI content: 0.4%
FT-IR and ¹³ C-NMR confirmed the presence of isocyanate, isocyanurate and urethane groups. This polyisocyanate is designated as A-1. After the inside of another reactor similar to the above reactor was replaced with nitrogen, 100 g of polyisocyanate A-1 was used, and methoxypolyethylene glycol having a number average molecular weight of 400 (MPEG-400,
16 g of methoxy PEG # 400 (manufactured by Toho Chiba Chemical Co., Ltd.) was charged and reacted at 75 ° C. for 3 hours. Isocyanate content: 16.9%, viscosity at 25 ° C .: 2,410 mP
a, a pale yellow transparent liquid self-emulsifiable polyisocyanate (A) having an average number of functional groups: 3.5 was obtained.

Production Example 2 Capacity with stirrer, thermometer, nitrogen seal tube, cooler:
In a 1,000 ml reactor, 300 g HDI, 2-n
-Butyl-2-ethyl-1,3-propanediol (D
MH), 11.9 g of MPEG-400, and 4 g of ricinoleic acid methyl ester were added, the inside of the reactor was replaced with nitrogen, and a urethanization reaction was performed at 75 ° C. for 3 hours with stirring. The measured isocyanate content of this reaction solution was 43.2%. Next, an isocyanurate-forming reaction was performed at 60 ° C. for 4.5 hours using 0.06 g of potassium propionate, 0.3 g of phenol, and 0.072 g of phosphoric acid as a catalyst. To this reaction solution, 0.042 g of phosphoric acid was added as a terminator, and after stirring at the reaction temperature for 1 hour, free HDI was removed by thin-film distillation (conditions: 120 ° C., 1.3 Pa). The obtained self-emulsifiable polyisocyanate (B), which is an isocyanurate / urethane-modified polyisocyanate, has an isocyanate content of 20.9% and a temperature of 25 ° C.
Was a pale yellow transparent liquid having a viscosity of 650 mPa, a free HDI content of 0.4%, and an average functional group number of 2.9. FT-IR and ¹³ C-
NMR measurement confirmed the presence of isocyanate, isocyanurate and urethane groups.

Production Example 3 Capacity with Stirrer, Thermometer, Nitrogen Seal Tube, Cooler:
After the inside of a 500 ml reactor was replaced with nitrogen, 100 g of polyisocyanate A-1 was used, and polyoxyethylene nonyl phenyl ether phosphate (trade name: Newcol 565-PS, acid phosphate manufactured by Nippon Emulsifier) was used as a surfactant. )), And mixed at 75 ° C. for 1 hour to obtain an isocyanate content:
A pale yellow transparent self-emulsifiable polyisocyanate (C) having 14.3%, a viscosity of 2,820 mPa at 25 ° C, and an average number of functional groups: 3.5 was obtained.

Production Example 4 Capacity with stirrer, thermometer, nitrogen sealed tube, cooler:
After replacing the inside of the 500 ml reactor with nitrogen, HDI was
0 g and 2.3 g of DMH, and stirred at 70 ° C.
For 3 hours. When the isocyanate content of the reaction solution at this time was measured, it was 49.1%. Next, 0.3 g of tributylphosphine was added as a catalyst, and uretdionation and isocyanuration were carried out at the same temperature for 8 hours. After adding 0.33 g of methyl paratoluenesulfonate to the reaction solution to stop the reaction, free HDI was removed by thin-film distillation (conditions: 120 ° C., 1.3 Pa). The obtained isocyanurate / uretdione / urethane-modified polyisocyanate A-2 has an isocyanate content of 22.3%, a viscosity at 25 ° C. of 100 mPa, and a free H content.
It was a pale yellow transparent liquid having a DI content of 0.4% and an average number of functional groups of 2.3. When the self-emulsifiable polyisocyanate (B) was measured by FT-IR and ¹³ C-NMR,
The presence of an isocyanate group, an isocyanurate group, a uretdione group, and a urethane group was confirmed. After the inside of another reactor similar to the above-mentioned reactor was replaced with nitrogen, 70 g of polyisocyanate A-2 and isophorone diisocyanate (I
30 g of isocyanurate-modified polyisocyanate (PDI) (trade name: Vestnut T-1890, NCO content: 17.0%, manufactured by Huls), MPEG-400
, And reacted at 75 ° C. for 3 hours. Isocyanate content: 16.4%, viscosity at 25 ° C .: 810 mP
a, a pale yellow transparent liquid self-emulsifiable polyisocyanate (D) having an average number of functional groups: 2.4 was obtained.

[Production of one-part thermosetting resin emulsion,
Storage stability] Example 1 Capacity with stirrer, thermometer, gas release valve, cooler:
A 2,000 ml reactor was charged with 300 g of self-emulsifying polyisocyanate (A) and 700 g of ion-exchanged water, and rapidly stirred at 2,000 rpm for 30 seconds to obtain an aqueous dispersion of polyisocyanate. Thereafter, the stirring speed was reduced, and the reaction was carried out at room temperature until the absorption peak of the isocyanate group of FT-IR was not confirmed, thereby obtaining a one-part thermosetting resin emulsion EM-1. The average particle size of EM-1 was 160 nm. When EM-1 was stored in a closed container in a cool dark place for 3 months, no change in appearance was observed.

Example 2 Capacity with stirrer, thermometer, gas release valve, cooler:
A 2,000 ml reactor was charged with 200 g of self-emulsifying polyisocyanate (B) and 800 g of ion-exchanged water, and rapidly stirred at 2,000 rpm for 30 seconds to obtain an aqueous dispersion of polyisocyanate. Thereafter, the stirring speed was reduced and the reaction was carried out at room temperature until the absorption peak of the isocyanate group of FT-IR was not confirmed, thereby obtaining a one-part thermosetting resin emulsion EM-2. The average particle size of EM-1 was 150 nm. When EM-2 was stored in a closed container in a cool dark place for 3 months, no change in appearance was observed.

Example 3 Capacity with stirrer, thermometer, gas release valve, cooler:
A 2,000 ml reactor was charged with 100 g of self-emulsifying polyisocyanate (C) and 900 g of ion-exchanged water, and rapidly stirred at 2,000 rpm for 30 seconds to obtain an aqueous dispersion of polyisocyanate. Thereafter, the stirring speed was reduced and the reaction was carried out at room temperature until the absorption peak of the isocyanate group of FT-IR was not confirmed, thereby obtaining a one-part thermosetting resin emulsion EM-3. The average particle size of EM-3 was 120 nm. When EM-3 was stored in a closed container in a cool dark place for 3 months, no change in appearance was observed.

Example 4 Capacity with stirrer, thermometer, gas release valve, cooler:
A 2,000 ml reactor was charged with 200 g of self-emulsifying polyisocyanate (D) and 800 g of ion-exchanged water, and rapidly stirred at 2,000 rpm for 30 seconds to obtain an aqueous dispersion of polyisocyanate. Thereafter, the stirring speed was reduced and the reaction was carried out at room temperature until the absorption peak of the isocyanate group of FT-IR was not confirmed, thereby obtaining a one-part thermosetting resin emulsion EM-4. EM-4 had an average particle size of 220 nm. When EM-4 was stored in a closed container in a cool dark place for 3 months, no change in appearance was observed.

Example 5 Capacity with stirrer, thermometer, gas release valve, cooler:
In a 2,000 ml reactor, 800 g of an aqueous acrylic emulsion (solid content: 50%, viscosity at 25 ° C: 300 mPa, trade name: WA-1015ND, manufactured by Asia Industries),
500 g of EM-4 was charged and mixed at room temperature for 1 hour to obtain a one-part thermosetting resin emulsion EM-5. EM-5
Was stored in a closed container in a cool dark place for 3 months, and no change in appearance was observed.

Comparative Example 1 Capacity with Stirrer, Thermometer, Gas Release Valve, Cooler:
A 2,000 ml reactor was charged with 300 g of self-emulsifying polyisocyanate (A) and 700 g of ion-exchanged water, and rapidly stirred at 2,000 rpm for 30 seconds to obtain a polyisocyanate aqueous dispersion EM-6. E just after dispersion
When M-6 was placed in a closed container and stored in a cool, dark place, the container was damaged the next day, and the liquid inside spilled.

Comparative Example 2 The aqueous acrylic emulsion used in Example 5 was EM-7. When EM-7 was stored in a closed container in a cool dark place for 3 months, no change in appearance was observed.

Examples 6 to 15 and Comparative Examples 3 and 4 EM-1 to 7 immediately after production and E stored for 3 months in a cool dark place
Each of M-1 to M-5 was used as an aqueous one-pack coating agent and evaluated. The coating agent was applied to an aluminum plate, and a coating was obtained by two-stage curing. Immediately after curing, the coatings were tested for performance. The results are shown in Tables 1 and 2. In Comparative Example 1 (EM-6), the appearance of the coating was extremely poor (bubbles and peeling were over the entire coating and the film thickness was not uniform), so other evaluations were omitted.

[Coating and curing conditions] Base material: Aluminum plate (50 mm × 25 mm × 0.
5mm) Degreasing with absorbent cotton impregnated with methyl ethyl ketone on the coating agent application surface. Coating amount: 50 g / m ² Coating temperature: 20 ° C. Curing conditions: Coating drying conditions; 70 ° C. × 20 minutes Curing time: 30 minutes Curing temperature: See Tables 1 and 2 [Performance test] Coating appearance: Visual observation of the coating surface Evaluation. Rubbing test: A cotton wool impregnated with xylene was rubbed 100 times, and a change in the appearance of the film was observed. Flex resistance: Measured according to JIS K5400. The mandrel diameter is 2mm. Adhesion: Measured according to JIS K5400, cross cut tape method

[0059]

[Table 1]

[0060]

[Table 2]

[Evaluation Criteria] Appearance ：: No cracking or peeling is observed in the coating ×: Cracking or peeling is observed in the coating XX: Rubbing test ○: Significant cracking or peeling is observed in the coating Few scratches, etc. can be hardly confirmed. △: Some scratches, etc. can be confirmed on the coating. ×: Flaws, etc. can be considerably confirmed on the coating. Adhesion observed ○: Residual film ratio of 80% or more Δ: Residual film ratio of 50% or more and less than 80% ×: Residual film ratio of less than 50%

[0062]

As described above, according to the present invention, for the first time, it is possible to provide an aqueous one-pack coating agent capable of expressing adhesion in a short time and obtaining a good film, and a coating method excellent in workability. It became.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B05D 7/24 302 B05D 7/24 302T C09D 5/02 C09D 5/02 F term (Reference) 4D075 BB26Z BB93Z CA13 CA47 EA13 EA19 EB38 4J038 DG051 DG061 DG081 DG101 DG111 DG121 DG131 DG161 DG171 DG211 DG221 DG271 DG281 DG291 JB05 JC40 KA04 KA20 MA08 MA10 MA15 NA01 NA12 NA14 NA23 NA26 NA27 PA19 PC02

Claims (3)

[Claims] 1. A one-part heat dispersing agent obtained by dispersing an organic polyisocyanate in water and reacting isocyanate groups with water until substantially no free isocyanate groups are present, and substantially free of free isocyanate groups. An aqueous one-pack coating agent comprising a curable resin emulsion. 2. The aqueous one-part coating agent according to claim 1, wherein the organic polyisocyanate is a self-emulsifying polyisocyanate. 3. After applying the aqueous one-pack coating agent according to claim 1 or 2 to a substrate at a temperature lower than 100 ° C.,
A coating method characterized in that the coating is thermally cured at a temperature of about 300 ° C.