JP2005194375A - Preparation method of polyurethane emulsion for aqueous one-component coating agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a preparation method of a polyurethane emulsion for an aqueous one-component coating agent, which is excellent in shelf stability and workability at application, is environmentally safe and yields a coating film excellent in appearance, water resistance and solvent resistance. <P>SOLUTION: In the preparation method of the polyurethane emulsion for the aqueous one-component coating agent, an organic diisocyanate (a1), a polymer polyol (a2) having a number average molecular weight of ≥250 and <1,000 and a carboxy group-containing low-molecular glycol (a3) are reacted to prepare a carboxy group-containing isocyanate group-terminated urethane prepolymer (A), the prepolymer (A) is mixed with a hydrophobic polyisocyanate (B), carboxy groups in the system is neutralized with a neutralizer (C), and the mixture is emulsified in water. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a polyurethane emulsion for aqueous one-component coating. More specifically, the present invention relates to a method for producing a polyurethane emulsion for an aqueous one-component coating agent that is safe in consideration of the environment, and has excellent productivity, storage stability, coating appearance, water resistance, solvent resistance, and the like. .

  A coating agent containing a large amount of organic solvent has adverse effects on the human body, safety and health problems such as explosion and fire, and pollution problems such as air pollution. In order to improve these problems, aqueous system development has been actively conducted in recent years. On the other hand, urethane-based coating agents exhibit good adhesion to various substrates. Therefore, there is an increasing demand for aqueous urethane coating agents.

  In Patent Document 1, a urethane prepolymer having a carboxyl group and an isocyanate group, which becomes water-dispersible by neutralizing the carboxyl group with a basic compound, and a non-water-emulsifiable polyisocyanate are mixed, and this is mixed with water. Shows an aqueous polyurethane resin emulsified and chain-extended.

JP-A-7-188371

  However, the water-based urethane resin described in Patent Document 1 does not disclose the molecular weight of the polymer polyol or the neutralization time in the production process, and it has been found that the film physical properties are insufficient.

  According to the present invention, it is possible to provide an aqueous one-component coating agent that is safe in consideration of the environment and excellent in productivity, storage stability, water resistance and solvent resistance of a coating film, and the like.

  An object of the present invention is to provide an aqueous one-component coating agent that is safe in consideration of the environment and is excellent in productivity, storage stability, water resistance and solvent resistance of a coating film, and the like.

  The present invention has been studied to solve the above-mentioned problems, and a polyurethane emulsion obtained by emulsifying a specific polyisocyanate in water and performing a chain extension reaction is suitable for an aqueous one-component coating agent. As a result, the present invention has been completed.

  That is, this invention is shown by following (1)-(4).

(1) A carboxyl group-containing isocyanate group-terminated urethane prepolymer by reacting an organic diisocyanate (a1), a polymer polyol (a2) having a number average molecular weight of 250 or more and less than 1,000, and a carboxyl group-containing low molecular glycol (a3). (A) is manufactured, and this and hydrophobic polyisocyanate (B) are mixed, Then, after neutralizing the carboxyl group in a system with a neutralizing agent (C), the said mixture is emulsified in water. A process for producing a polyurethane emulsion for an aqueous one-component coating agent.

(2) The production method of (1) above, wherein the organic diisocyanate (a1) is an aliphatic diisocyanate and / or an alicyclic diisocyanate.

(3) The production method of the above (1) to (2), wherein the polymer polyol (a2) has a carbonate skeleton or a phthalate skeleton.

(4) The hydrophobic polyisocyanate (B) is an isocyanurate-modified product or an isocyanurate-modified composite product of an aliphatic diisocyanate and / or an alicyclic diisocyanate (1) to (1) to (3) Production method.

The present invention will be described in further detail.
The carboxyl group-containing isocyanate group-terminated urethane prepolymer (A) constituting the present invention is obtained by reacting an organic diisocyanate (a1), a polymer polyol (a2), and a carboxyl group-containing low molecular glycol (a3). is there.

  The carboxylate content in (A) is preferably from 0.3 to 2.5 mmol / g, particularly preferably from 0.5 to 2 mmol / g. When the carboxylate content is too low, it is difficult to obtain the target polyurethane emulsion. When it is too much, it may contribute to an increase in viscosity during emulsification and a decrease in durability of the coating.

  The organic diisocyanate (a1) used in the present invention is 2,4-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-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate Aromatic isocyanates such as socyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, aromatic polyisocyanates such as polyphenylene polymethylene polyisocyanate, crude tolylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocyanate And alicyclic diisocyanates such as lysine diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and tetramethylxylene diisocyanate. These allophanate-modified products, urea-modified products, biuret-modified products, uretdione-modified products, and isocyanurate-modified products may be used in combination.

  Preferred organic diisocyanates in the present invention are preferably aliphatic diisocyanates and alicyclic diisocyanates, particularly hexamethylene diisocyanate and isophorone diisocyanate in view of the strength and weather resistance of the film.

  The polymer polyol (a2) used in the present invention is a polyester polyol, polyesteramide polyol, polyether polyol, polyether / ester polyol, polycarbonate having a number average molecular weight of 250 or more and less than 1,000, preferably 300 or more and 800 or less. There are polyols, polyolefin polyols, etc., and these polymer polyols may be used alone or in combination.

  Polyester polyols and polyester amide polyols include polycarboxylic acid derivatives such as polycarboxylic acids, acid esters, acid anhydrides, acid halides, low molecular polyols having a molecular weight of less than 500 (number average), low molecular polyamines, and low molecular amino alcohols. It is obtained by the reaction with.

  Examples of the polycarboxylic acid include succinic acid, adipic acid, sebacic acid, azelaic acid, terephthalic acid, isophthalic acid, orthophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, and dimer acid.

  (Number average) Low molecular polyols having a molecular weight of less than 250 include ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,2-butanediol, 1,3-butanediol, and 1,4-butane. Diol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, 3,3-di Methylol heptane, diethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 2-ethyl-1,3-propanediol, 2-normalpropyl-1,3-propanediol, 2-isopropyl-1,3 -Propanediol, 2-normalbutyl-1,3-propanediol, -Isobutyl-1,3-propanediol, 2-tertiarybutyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol 2-ethyl-2-normalpropyl-1,3-propanediol, 2-ethyl-2-normalbutyl-1,3-propanediol, 2-ethyl-3-ethyl-1,4-butanediol, 2- Methyl-3-ethyl-1,4-butanediol, 2,3-diethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2,3,4-triethyl-1,5 -Pentanediol, trimethylolpropane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, pentaerythritol, bisphenol A Alkylene oxide adducts, and the like.

  Examples of the low molecular weight polyamine having a (number average) molecular weight of less than 250 include ethylenediamine, hexamethylenediamine, xylylenediamine, isophoronediamine, and diethylenetriamine.

  Examples of the low molecular amino alcohol having a (number average) molecular weight of less than 250 include monoethanolamine, diethanolamine, and monopropanolamine. Also suitable are polyester polyols such as lactone polyester polyols obtained by ring-opening polymerization of cyclic ester (lactone) monomers such as ε-caprolactone, alkyl-substituted ε-caprolactone, δ-valerolactone, and alkyl-substituted δ-valerolactone. Can be used.

  Examples of the polyether polyol include polyethylene glycol, polypropylene ether polyol, and polytetramethylene ether polyol.

  Examples of polyether ester polyols include polyester polyols produced from the above polyether polyols and the above polycarboxylic acid derivatives.

  The polycarbonate polyol is generally obtained by a deethanol condensation reaction of a low molecular polyol and diethyl carbonate, a dephenol condensation reaction of a low molecular polyol and diphenyl carbonate, or a deethylene glycol condensation reaction of a low molecular polyol and ethylene carbonate. As a low molecular polyol used here, the low molecular polyol used for obtaining the above-mentioned polyester polyol is mentioned.

  Specific examples of the polyolefin polyol include a hydroxyl group-terminated polybutadiene, a hydrogenated product thereof, and a hydroxyl group-containing chlorinated polyolefin.

  In consideration of various durability and adhesion of the film made of the polyurethane emulsion obtained in the present invention, the polymer polyol (a2) preferably has a carbonate skeleton or a phthalate skeleton.

  Examples of the carboxyl group-containing low molecular weight glycol (a3) used in the present invention include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, and the like. Is mentioned.

  Hydrophobic polyisocyanate (B) used in the present invention does not have water solubility or dispersibility (emulsification) properties, in addition to non-modified polyisocyanates such as polyphenylene polymethylene polyisocyanate and crude tolylene diisocyanate, Examples of the above-mentioned urethane-modified products of urea, urea-modified products, allophanate-modified products, biuret-modified products, uretdione-modified products, isocyanurate-modified products, and composite modified products thereof. In addition, when using a modifier, this modifier does not have a polar group. When (B) is a hydrophilic polyisocyanate, the water resistance of the coating becomes insufficient.

  In consideration of various durability and adhesion of the film made of the polyurethane emulsion obtained in the present invention, the hydrophobic polyisocyanate (B) is an isocyanurate modified product or isocyanurate of an aliphatic diisocyanate and / or an alicyclic diisocyanate. Complex modified products including modification (hereinafter collectively referred to as isocyanurate-modified non-yellowing polyisocyanate) are preferred. The aliphatic diisocyanate is preferably hexamethylene diisocyanate, and the alicyclic diisocyanate is preferably isophorone diisocyanate.

The isocyanurate-modified non-yellowing polyisocyanate will be further described in detail.
The method for producing the isocyanurate-modified non-yellowing polyisocyanate includes 1) adding an isocyanurate-forming catalyst to an aliphatic diisocyanate and / or an alicyclic diisocyanate, followed by an isocyanuration reaction, 2) removing the alicyclic diisocyanate, 2) urethanizing the aliphatic diisocyanate and / or alicyclic diisocyanate with the low molecular polyol used to obtain the polyester polyol, and then forming the isocyanurate An isocyanuration reaction is carried out by adding a catalyst, and then unreacted aliphatic diisocyanate and / or alicyclic diisocyanate is removed. 3) Some isocyanate groups of the polyisocyanate obtained in 1) or 2) above And monofunctional or polyfunctional without hydrophilic groups For further urethanization reaction and ability polyol, and the like.

  Examples of the isocyanuration catalyst used in the production methods 1) and 2) include tetraalkylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, tetraalkylammonium hydroxide, tetramethylammonium acetate, acetic acid Organic weak acid salts such as tetraethylammonium salt and tetrabutylammonium acetate, trialkylhydroxyalkylammonium hydroxide such as trimethylhydroxypropylammonium hydroxide, trimethylhydroxyethylammonium hydroxide, triethylhydroxypropylammonium hydroxide, triethylhydroxyethylammonium hydroxide Oxide, acetate Organic weak acid salts such as methylhydroxypropylammonium salt, trimethylhydroxyethylammonium acetate acetate, triethylhydroxypropylammonium acetate acetate, triethylhydroxyethylammonium acetate acetate, tertiary amines such as triethylamine and triethylenediamine, acetic acid, caproic acid, octylic acid, Examples thereof include metal salts of alkyl carboxylic acids such as myristic acid.

  The amount of catalyst added in the isocyanuration reaction is preferably 10 to 10,000 ppm with respect to the reaction system. The reaction rate is preferably 40% or less, and more preferably 35% or less. The isocyanurate reaction temperature is preferably 0 to 120 ° C, particularly preferably 20 to 100 ° C.

  Examples of the neutralizing agent (C) used in the present invention include ethylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, triethanolamine, triisopropanolamine, N-methyldiethanolamine, N-phenyldiethanolamine, monoethanolamine, N , N-dimethylethanolamine, N, N-diethylethanolamine, morpholine, N-methylmorpholine, organic amines such as 2-amino-2-ethyl-1-propanol, alkali metals such as lithium, potassium and sodium, water Examples include sodium oxide, inorganic alkalis of potassium hydroxide, ammonia and the like, but in order to improve the weather resistance and water resistance after drying, a highly volatile one that is easily dissociated by heat or a polyisocyanate curing agent and Amino alcohol is preferable to respond, especially ammonia, trimethylamine, triethylamine, N, N-dimethylaminoethanol amines are preferred.

A specific manufacturing process will be described.
First, the aforementioned organic diisocyanate (a1), polymer polyol (a2), and carboxyl group-containing low-molecular glycol (a3) are reacted under the condition of hydroxyl group <isocyanate group, and a carboxyl group-containing isocyanate group-terminated urethane prepolymer ( A) is manufactured. At this time, a known urethanization catalyst may be used. The reaction temperature is preferably 0 to 100 ° C, particularly preferably 20 to 90 ° C.

  At the time of producing the prepolymer, it is preferable to dilute to an arbitrary solid content with an organic solvent that is inert to the isocyanate group, in view of the stirring efficiency and the like. Examples of organic solvents include aromatic solvents such as toluene, xylene, swazole (aromatic hydrocarbon solvent manufactured by Cosmo Oil Co., Ltd.), Solvesso (aromatic hydrocarbon solvent manufactured by Exxon Chemical Co., Ltd.), Aliphatic hydrocarbon fillers such as hexane, alicyclic hydrocarbon solvents such as cyclohexane and isophorone, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ester systems such as ethyl acetate, butyl acetate and isobutyl acetate Solvents, glycol ether ester solvents such as ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol 3-methyl-3-methoxybutyl acetate, ethylene glycol ethyl-3-ethoxypropionate, ethyl Glycol dimethyl ether, diethylene glycol dibutyl ether, propylene glycol dibutyl ether, glycol ether solvents such as dipropylene glycol dimethyl ether, ether solvents such as tetrahydrofuran and dioxane, aprotic polar solvents such as N-methylpyrrolidone and hexamethylphosphoramide, etc. Is mentioned. The said solvent may contain 1 type (s) or 2 or more types.

  In the present invention, an aprotic polar solvent, a glycol ether ester solvent, or a glycol ether solvent that has a low vapor pressure and does not exhibit a flash point even when present in an emulsion is preferable. Good N-methylpyrrolidone and glycol ether solvents are preferred.

  After mixing hydrophobic polyisocyanate (B) with the obtained carboxyl group-containing isocyanate group-terminated urethane prepolymer (A), the carboxyl groups in the system are neutralized with a neutralizing agent (C). It is important to carry out neutralization before emulsification. When neutralization is performed simultaneously with emulsification or after emulsification, precipitates and suspended matters are likely to be generated.

  The mass blending ratio of (B) is preferably (A) / (B) = 100/10 to 100/100 with respect to (A), and particularly (A) / (B) = 100/20 to 100/100. preferable. When the amount of (B) is too small, the strength and durability of the coating tends to be insufficient. When (B) is too much, emulsification tends to be difficult.

  Next, the mixture is emulsified in water to perform a chain extension reaction. As a chain extender during the chain extension reaction, water, ethylenediamine, hexamethylenediamine, xylylenediamine, isophoronediamine, diethylenetriamine, N-aminoethyl-N-ethanolamine, etc. Molecular polyamines are mentioned.

  In the case of using a low molecular weight polyamine, the polyamine is dissolved in water in advance, and a mixture of the above-mentioned (A) and (B) is charged into this polyamine aqueous solution to carry out the emulsification and chain extension reaction. After the mixture of (A) and (B) is emulsified in water, an aqueous solution of polyamine in which polyamine is dissolved in water is charged to carry out a chain extension reaction.

  In the chain extension reaction, a decarbonation gas reaction occurs due to a reaction between an isocyanate group and water, so it is important not to seal the reaction system.

  The point at which no isocyanate groups remain is the end point of the reaction. The reaction temperature during chain extension is preferably 20 to 50 ° C.

  The average particle size of the polyurethane emulsion obtained by the present invention is preferably 500 nm or less, particularly preferably 300 nm or less. If the average particle size is too large, precipitates and suspended matter may be generated.

  The aqueous polyurethane emulsion obtained by the present invention can contain additives and auxiliaries commonly used in aqueous systems. Examples of the additives and auxiliaries include pigments, dyes, antiseptics, antifungal agents, antibacterial agents, thixotropic agents, antiblocking agents, dispersion stabilizers, viscosity modifiers, film forming aids, leveling agents, gels. Antioxidants, light stabilizers, antioxidants, ultraviolet absorbers, inorganic and organic fillers, plasticizers, lubricants, antistatic agents, reinforcing materials, catalysts and the like.

  The aqueous coating agent using the polyurethane emulsion obtained by the present invention will be described.

As a method of using the aqueous coating agent using the polyurethane emulsion obtained by the present invention, it is applied to a substrate, dried and heated to form a film. The temperature at which the substrate is applied is less than 80 ° C., preferably room temperature, in order to prevent sagging during application. The base material is preferably heat-resistant because it is heat-cured after application of the coating agent, and specifically, one having a heat distortion temperature of 80 ° C. or higher is preferable. Examples of such base materials include metal base materials such as iron, copper, aluminum, and stainless steel, heat-resistant plastics such as epoxy resins, phenol resins, polyamide resins, and polysulfone resins, ceramics, glass, concrete, and stone materials. . In the present invention, a metal base material is preferred. The coating amount of the coating agent is preferably 1 to 300 g / m ² , particularly 1 to 200 g / m ² in terms of solid content of 100% by mass.

  As a coating method, known methods such as doctor blade, reverse roll, gravure roll, spinner coat, extruder, spray coat, dip coat, flow coat, wire coat and the like are used.

  After apply | coating a coating agent to a base material, temperature is 80-300 degreeC, Preferably it heat-hardens at 100-280 degreeC. The heating time is preferably 10 seconds to 10 minutes, particularly preferably 20 seconds to 5 minutes. Since the present invention can develop the coating strength in a short time, an excessively long heating time not only wastes energy but also gives an unnecessary heat history to the coating agent layer.

  The conventional one-pack type aqueous coating agent is not always satisfactory in film physical properties and is particularly unsatisfactory in durability. However, the aqueous one-component coating agent using the polyurethane emulsion of the present invention is a two-component type. The film properties are comparable to In addition, since one liquid has sufficient physical properties, there is an advantage that a step of liquid blending immediately before use is not required, and a coating physical property defect due to a blending error does not occur.

  The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited thereto. In Examples and Comparative Examples, “%” means “% by mass”.

[Production of isocyanurate-modified non-yellowing polyisocyanate]
Synthesis example 1
Capacity equipped with stirrer, thermometer, nitrogen seal tube, and condenser: A 500 ml reactor was charged with 300 g of hexamethylene diisocyanate (HDI) and 2.8 g of 1,3-butanediol (1,3-BD). After charging, the inside of the reactor was purged with nitrogen, heated to a reaction temperature of 80 ° C. with stirring, and reacted at the same temperature for 2 hours. When the isocyanate content of this reaction liquid was measured, it was 48.6%. Next, 0.06 g of potassium caprate as a catalyst and 0.3 g of phenol as a cocatalyst were added, and an isocyanuration reaction was performed at 60 ° C. for 6 hours. 0.042 g of phosphoric acid was added to this reaction solution as a terminator, and after stirring for 1 hour at the reaction temperature, free HDI was removed by thin film distillation under the conditions of 120 ° C. and 1.3 kPa, and isocyanurate-modified polyisocyanate NCO— 1 was obtained. NCO-1 had a pale yellow transparent liquid, an isocyanate content of 21.3%, a viscosity at 25 ° C. of 2,200 mPa · s, and a free HDI content of 0.3%.

Synthesis example 2
After charging 300 g of HDI in the same apparatus as in Synthesis Example 1, the inside of the reactor was purged with nitrogen. Next, 0.06 g of potassium caprate as a catalyst and 0.3 g of phenol as a cocatalyst were added, and an isocyanuration reaction was performed at 60 ° C. for 6 hours. 0.042 g of phosphoric acid was added to this reaction solution as a terminator, and after stirring for 1 hour at the reaction temperature, free HDI was removed by thin film distillation under the conditions of 120 ° C. and 1.3 kPa, and isocyanurate-modified polyisocyanate NCO— 3 was obtained. NCO-3 had a pale yellow transparent liquid, an isocyanate content of 25.1%, a viscosity at 25 ° C. of 1,200 mPa · s, and a free HDI content of 0.3%.

Synthesis example 3
The same apparatus as in Synthesis Example 1 was charged with 300 g of NCO-1 and 48 g of methoxypolyethylene glycol having a number average molecular weight of 400, the inside of the reactor was purged with nitrogen, and the mixture was heated to a reaction temperature of 80 ° C. while stirring. Reaction was performed at temperature for 2 hours to obtain isocyanurate-modified polyisocyanate NCO-2. NCO-2 had a pale yellow transparent liquid, an isocyanate content of 16.5%, a viscosity at 25 ° C. of 2,300 mPa · s, and a free HDI content of 0.3%.

[Production of polyurethane emulsion]
Example 1
Capacity equipped with stirrer, thermometer, nitrogen seal tube and condenser: 3,000 ml reactor, 121.7 g polyol-1, 36.0 g 2,2-dimethylolbutanoic acid (DMBA) 75 g of propylene glycol dimethyl ether (DMFDG) was charged and dissolved by heating at 90 ° C. for 10 minutes. After cooling to 60 ° C., 140.4 g of isophorone diisocyanate (IPDI) and 0.02 g of dioctyltin dilaurate (DOTDL) were charged and reacted at 80 ° C. for 2 hours to obtain a carboxyl group-containing isocyanate group-terminated prepolymer solution. The isocyanate content of this prepolymer solution was 3.3%. Next, 59.6 g of NCO-1 was added and mixed uniformly, then 24.6 g of triethylamine (TEA) was added to neutralize the carboxyl group, and then 556 g of water was added with stirring, emulsification and chain extension by water. The reaction was carried out at 30 ° C. for 12 hours. During the reaction, generation of carbon dioxide gas was confirmed. When the presence of isocyanate groups was no longer confirmed by FT-IR, an aqueous polyurethane emulsion PU-1 was obtained. The solid content of PU-1 was 35.2%, the average particle size was 52 nm, and the viscosity at 25 ° C. was 107 mPa · s.

Example 2
A reactor similar to that of Example 1 was charged with 98.2 g of polyol-1, 29.1 g of DMBA, and 75 g of NMP, and heated and dissolved at 90 ° C. for 10 minutes. After cooling to 60 ° C., 113.4 g of IPDI was charged and reacted at 80 ° C. for 3 hours to obtain a carboxyl group-containing isocyanate group-terminated prepolymer solution. The isocyanate content of this prepolymer solution was 3.1%. Next, 120.3 g of NCO-1 was added and mixed uniformly, and then 19.8 g of TEA was added to neutralize the carboxyl group, and then 563 g of water was added while stirring to carry out emulsification and chain extension reaction with water by 30. This was carried out at ° C for 12 hours. During the reaction, generation of carbon dioxide gas was confirmed. When the presence of isocyanate groups was no longer confirmed by FT-IR, an aqueous polyurethane emulsion PU-2 was obtained. The solid content of PU-2 was 35.1%, the average particle size was 68 nm, and the viscosity at 25 ° C. was 50 mPa · s.

Example 9
A reactor similar to that of Example 1 was charged with 95.6 g of polyol-1, 35.4 g of DMBA, and 75 g of DMFDG, and dissolved by heating at 90 ° C. for 10 minutes. After cooling to 60 ° C., 118.9 g of IPDI and 0.02 g of DOTDL were charged and reacted at 80 ° C. for 2 hours to obtain a carboxyl group-containing isocyanate group-terminated prepolymer solution. The isocyanate content of this prepolymer solution was 2.7%. Next, after 50.0 g of NCO-1 was charged and mixed uniformly, 24.1 g of TEA was charged to neutralize the carboxyl group, and then 579 g of water was added and emulsified with stirring. Thereafter, an amine aqueous solution in which 4.0 g of ethylenediamine (EDA) and 0.4 g of monoethanolamine (MEA) were dissolved in 25 g of water in advance, and chain extension reaction was performed at 30 ° C. for 12 hours. During the reaction, generation of carbon dioxide gas was confirmed. When the presence of isocyanate groups was no longer confirmed by FT-IR, an aqueous polyurethane emulsion PU-9 was obtained. The solid content of PU-9 was 35.1%, the average particle size was 18 nm, and the viscosity at 25 ° C. was 125 mPa · s.

Examples 3, 5, and 7
Using the raw materials shown in Tables 1 and 2, aqueous polyurethane emulsions PU-3, 5 and 7 were obtained in the same manner as in Example 1.

Examples 4 and 6
Using the raw materials shown in Table 1, aqueous polyurethane emulsions PU-4 and 6 were obtained in the same manner as in Example 2.

Comparative Example 1
In the same reactor as in Example 1, 114.4 g of polyol-1 and 75 g of DMFDG were charged and dissolved by heating at 90 ° C. for 10 minutes. After cooling to 60 ° C., 66.1 g of IPDI was charged and reacted at 80 ° C. for 2 hours to obtain an isocyanate group-terminated prepolymer solution. The isocyanate content of this prepolymer solution was 2.3%. Next, 180.5 g of NCO-2 was charged and mixed uniformly, 583 g of water was charged while stirring, and chain extension reaction with emulsification and water was carried out at 30 ° C. for 12 hours. During the reaction, generation of carbon dioxide gas was confirmed. When the presence of isocyanate groups was no longer confirmed by FT-IR, an aqueous polyurethane emulsion PU-10 was obtained. Since precipitation was confirmed for PU-10, the subsequent evaluation was not performed.

Comparative Example 2
In the same reactor as in Example 1, 144.7 g of polyol-1, 42.8 g of DMBA, and 75 g of DMFDG were charged and dissolved by heating at 90 ° C. for 10 minutes. After cooling to 60 ° C., 167.0 g of IPDI and 0.02 g of DOTDL were charged and reacted at 80 ° C. for 2 hours to obtain a carboxyl group-containing isocyanate group-terminated prepolymer solution. The isocyanate content of this prepolymer solution was 3.4%. Next, after 29.2 g of TEA was charged to neutralize the carboxyl group, 548 g of water was charged while stirring, and chain extension reaction with emulsification and water was performed at 30 ° C. for 12 hours. During the reaction, generation of carbon dioxide gas was confirmed. When the presence of isocyanate groups was no longer confirmed by FT-IR, an aqueous polyurethane emulsion PU-11 was obtained. The solid content of PU-11 was 35.2%, the average particle size was 35 nm, and the viscosity at 25 ° C. was 154 mPa · s.

Comparative Example 3
In the same reactor as in Example 1, 186.4 g of polyol-4, 13.8 g of DMBA, and 100 g of DMFDG were charged and dissolved by heating at 90 ° C. for 10 minutes. After cooling to 60 ° C., 53.8 g of IPDI and 0.02 g of DOTDL were charged and reacted at 80 ° C. for 2 hours to obtain a carboxyl group-containing isocyanate group-terminated prepolymer solution. The isocyanate content of this prepolymer solution was 1.3%. Next, 50.8 g of NCO-1 was added and mixed uniformly, and then 9.4 g of TEA was added to neutralize the carboxyl group, and then 594 g of water was added in advance with stirring, followed by emulsification and chain extension reaction with water. This was carried out at 30 ° C. for 12 hours. During the reaction, generation of carbon dioxide gas was confirmed. When the presence of isocyanate groups was no longer confirmed by FT-IR, an aqueous polyurethane emulsion PU-12 was obtained. The solid content of PU-12 was 29.9%, the average particle size was 72 nm, and the viscosity at 25 ° C. was 154 mPa · s.

Comparative Example 4
A reactor similar to that of Example 1 was charged with 121.7 g of polyol-1, 36.0 g of DMBA, and 75 g of DMFDG, and heated and dissolved at 90 ° C. for 10 minutes. After cooling to 60 ° C., 140.4 g of IPDI and 0.02 g of DOTDL were charged and reacted at 80 ° C. for 2 hours to obtain a carboxyl group-containing isocyanate group-terminated prepolymer solution. The isocyanate content of this prepolymer solution was 3.3%. Next, 59.6 g of NCO-1 was charged and mixed uniformly, and then an aqueous amine solution in which 24.6 g of TEA was dissolved was added to 555 g of water. Went for hours. During the reaction, generation of carbon dioxide gas was confirmed. When the presence of isocyanate groups was no longer confirmed by FT-IR, an aqueous polyurethane emulsion PU-13 was obtained. Since precipitation was confirmed for PU-13, the subsequent evaluation was not performed.

Comparative Example 5
In a reactor similar to Example 1, 100 g of DMFDG and 368.8 g of NCO-2 were charged and mixed uniformly, then 563 g of water was charged with stirring, and the chain extension reaction with emulsification and water was carried out at 30 ° C. for 12 Went for hours. During the reaction, generation of carbon dioxide gas was confirmed. When the presence of isocyanate groups was no longer confirmed by FT-IR, an aqueous polyurethane emulsion PU-14 was obtained. The solid content of PU-14 was 35.1%, the average particle size was 200 nm, and the viscosity at 25 ° C. was 10 mPa · s.

Comparative Example 6
In the same reactor as in Example 1, 67.2 g of polyol-5, 45.0 g of DMBA, and 100 g of DMFDG were charged and dissolved by heating at 90 ° C. for 10 minutes. After cooling to 60 ° C., 193.9 g of IPDI and 0.02 g of DOTDL were charged and reacted at 80 ° C. for 2 hours to obtain a carboxyl group-containing isocyanate group-terminated prepolymer solution. The isocyanate content of this prepolymer solution was 4.2%. Next, 61.2 g of NCO-1 was added and mixed uniformly, and then 33.9 g of TEA was added to neutralize the carboxyl group, and then 506 g of water was added in advance while stirring, followed by emulsification and chain extension reaction with water. This was carried out at 30 ° C. for 12 hours. During the reaction, generation of carbon dioxide gas was confirmed. When the presence of isocyanate groups was no longer confirmed by FT-IR, an aqueous polyurethane emulsion PU-15 was obtained. The solid content of PU-15 was 35.1%, the average particle size was 829 nm, and the viscosity at 25 ° C. was 239 mPa · s.

Example 2
A reactor similar to that of Example 1 was charged with 121.3 g of polyol-1, 35.9 g of DMBA, and 75 g of DMFDG, and heated and dissolved at 90 ° C. for 10 minutes. After cooling to 60 ° C., 140.1 g of IPDI and 0.02 g of DOTDL were charged and reacted at 80 ° C. for 3 hours to obtain a carboxyl group-containing isocyanate group-terminated prepolymer solution. The isocyanate content of this prepolymer solution was 3.3%. Next, 59.5 g of NCO-3 was added and mixed uniformly, and then 24.5 g of TEA was added to neutralize the carboxyl group, and then 563 g of water was added with stirring, followed by emulsification and chain extension reaction with water by 30. This was carried out at ° C for 12 hours. During the reaction, generation of carbon dioxide gas was confirmed. When the presence of isocyanate groups was no longer confirmed by FT-IR, an aqueous polyurethane emulsion PU-15 was obtained. The solid content of PU-15 was 35.1%, the average particle size was 46 nm, and the viscosity at 25 ° C. was 139 mPa · s.

  Tables 1 and 2 show the charged amounts of raw materials and production results of Examples and Comparative Examples.

In Examples 1 to 8, Comparative Examples 1 to 7, and Tables 1 to 2, polyol-1:
Polycarbonate diol polyol-2 having a number average molecular weight of 500 obtained from 1,6-hexanediol and diethyl carbonate:
Polyesterdiol polyol-3 having a number average molecular weight of 500 obtained from ethylene glycol and a mixed dicarboxylic acid of terephthalic acid / isophthalic acid = 1/1 (molar ratio):
Polyester diol polyol-4 having a number average molecular weight of 500 obtained from a mixed dicarboxylic acid of ethylene glycol / neopentyl glycol = 1/1 (molar ratio) and terephthalic acid / isophthalic acid = 1/1 (molar ratio):
Polycarbonate diol polyol-5 having a number average molecular weight of 2,000 obtained from 1,6-hexanediol and diethyl carbonate:
Polycarbonate diol DMBA having a number average molecular weight of 200 obtained from 1,6-hexanediol and diethyl carbonate:
2,2-dimethylolbutanoic acid IPDI:
Isophorone diisocyanate DOTDL:
Dioctyltin dilaurate DMFDG:
Dipropylene glycol dimethyl ether NMP:
N-methylpyrrolidone TEA:
Triethylamine EDA:
Ethylenediamine MEA:
Monoethanolamine * Stability test The appearance after adding 30 g of water to 100 g of the obtained aqueous polyurethane emulsion was evaluated. “Good” if there is no change in appearance.

[Evaluation of aqueous one-component coating agent]
Application Example 1
PU-1 was applied to an aluminum plate so that the dry film thickness was 10 μm, allowed to stand at room temperature for 2 hours, then baked at 220 ° C. for 150 seconds to form a film, and an evaluation sample was obtained. . The following evaluation tests were performed using this evaluation sample. The results are shown in Table 3.
Pencil Hardness Test The pencil hardness test was performed in accordance with the handwriting method of the pencil scratch value test of JIS K5400.
Water Resistance Test The evaluation sample was immersed in warm water at 50 ° C. for 240 hours to evaluate the coating appearance.
Solvent resistance test Absorbent cotton was impregnated with methyl ethyl ketone, and the coating surface was rubbed 200 times to evaluate the coating appearance.

Application Examples 2-8, Application Comparative Examples 1-5
PU-2 to 8, 10, 11, 13, 14, and 15 were evaluated in the same manner as in Application Example 1. The results are shown in Tables 3 and 4. Note that PU-13 was not evaluated in the water resistance test because the coating whitened immediately after the evaluation sample was immersed.

All of the aqueous one-part coating agents using the aqueous polyurethane emulsions of the examples gave good results. On the other hand, in the comparative example, since PU-10 did not introduce a crosslinked structure, water resistance and solvent resistance were insufficient. PU-11 having a large number average molecular weight of the polyol in the prepolymer had a low film hardness. The self-emulsifying polyisocyanate-only PU-13 had insufficient water resistance. As a result of the water resistance test of PU-14, the coating whitened. This is probably because the (number average) molecular weight of the polyol used in the prepolymer is too small, and the concentration of urethane groups and urea groups in the coating becomes relatively large and these aggregate. Also in PU-15, some whitening of the coating was observed in the water resistance test results, although not as much as PU-14. This seems to be because water was drawn into the coating because hydrophilic polyisocyanate was used as the polyisocyanate.

Claims (4)

  An organic diisocyanate (a1), a polymer polyol (a2) having a number average molecular weight of 250 or more and less than 1,000, and a carboxyl group-containing low molecular glycol (a3) are reacted to form a carboxyl group-containing isocyanate group-terminated urethane prepolymer (A). And after mixing this and the hydrophobic polyisocyanate (B), the carboxyl group in the system is neutralized with a neutralizing agent (C), and then the mixture is emulsified in water. A method for producing a polyurethane emulsion for an aqueous one-component coating agent.   The method according to claim 1, wherein the organic diisocyanate (a1) is an aliphatic diisocyanate and / or an alicyclic diisocyanate.   The production method according to claim 1 or 2, wherein the polymer polyol (a2) has a carbonate skeleton or a phthalate skeleton. The hydrophobic polyisocyanate (B) is an isocyanurate-modified product of an aliphatic diisocyanate and / or an alicyclic diisocyanate or a complex-modified product containing an isocyanurate-modified product. 2. The production method according to item 1.