JP2010229224A - Water-based polyurethane dispersion and water-based paint using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous polyurethane dispersion which, in various applications of an aqueous polyurethane resin such as an aqueous coating and aqueous adhesive, especially, can preferably be used in fields requiring excellent solvent resistance. <P>SOLUTION: This aqueous polyurethane dispersion which satisfies all specific requirements is produced by reacting: an organic polyisocyanate (A) containing specific allophanate-modified polyisocyanate; high molecular weight polyol (B); low molecular weight glycol (C) containing a carboxyl group; a neutralizing agent (D); and chain extender (E). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an aqueous polyurethane dispersion excellent in water solubility and re-dissolution property of a dry film and insoluble in an organic solvent such as MEK, and an aqueous coating material using the same.

Aqueous polyurethane dispersions are excellent in adhesion to substrates, abrasion resistance, impact resistance, solvent resistance, etc., so paper, plastics, films, metals as paints, inks, adhesives and various coating agents It is widely used for textile products and the like, and various methods for producing the same have been studied. For example, acetone, methyl ethyl ketone, N-methyl pyrrolidone, aromatic organic solvent, etc. are used alone or mixed with a urethane resin solution in a mixed solvent, and then subjected to water dispersion and solvent removal process to obtain an aqueous solution such as emulsion, colloidal dispersion, aqueous solution, etc. Polyurethane resins have been developed.

Allophanate-modified polyisocyanates generally have low viscosity compared to other urethane-modified polyisocyanates and isocyanurate-modified polyisocyanates, and various side chain groups are introduced into the isocyanate skeleton depending on the choice of the modifier. be able to. For example, if a polyoxyethylene group is introduced, a hydrophilic polyisocyanate can be obtained. If a hydrocarbon group having a large number of carbon atoms is introduced, a poor solvent-soluble polyisocyanate can be obtained.

Patent Document 1 discloses an aqueous polyurethane emulsion in which an allophanate-modified polyisocyanate having a polyoxyethylene group introduced into a side chain is used as an isocyanate component of a polyurethane resin. However, in Patent Document 1, an organic diisocyanate (asymmetric diisocyanate) having two isocyanate groups having different reactivities such as 2,4-tolylene diisocyanate and isophorone diisocyanate is used as a raw material for allophanate-modified polyisocyanate. Since general asymmetric organic diisocyanates usually have a ring structure (a kind of ladder structure), the flexibility of the molecular skeleton is low and the viscosity tends to be high.

Patent Document 2 proposes a method that does not use an organic solvent when producing an aqueous polyurethane resin dispersion. However, in the production method of Patent Document 2, since the viscosity of the isocyanate group-terminated prepolymer is very high, water dispersion does not proceed unless a homomixer, homogenizer, or microfluidizer having a strong shearing force is used. In many cases, it is necessary to modify the manufacturing equipment.

  On the other hand, a dry film obtained by using an aqueous polyurethane dispersion is required to have excellent water solubility and re-solubility and properties that are insoluble in organic solvents such as MEK.

JP-A-1-104612 Japanese Patent Laid-Open No. 10-265539

  In view of the background as described above, the present invention provides an aqueous polyurethane dispersion that has excellent water-solubility and re-solubility, and that is insoluble in organic solvents such as MEK. The purpose is to obtain.

  Another object of the present invention is to obtain an aqueous paint using an aqueous polyurethane dispersion having the above-mentioned characteristics.

  As a result of intensive studies to solve the above series of problems, the present inventors have found that the above series of problems can be solved by using an aqueous polyurethane dispersion satisfying specific requirements. It came to complete.

  That is, this invention is shown by the following (1)-(5).

(1) A polyurethane resin obtained by reacting an organic polyisocyanate (A), a polymer polyol (B), a carboxyl group-containing low molecular glycol (C), a neutralizer (D), and a chain extender (E) in water. In the aqueous polyurethane dispersion obtained by emulsifying, the organic polyisocyanate (A) contains an alkoxy poly (oxyalkylene) glycol (A1-1) containing 50 mol% or more of oxyethylene groups in the repeating unit and hexamethylene diisocyanate (A1). -2) contains the allophanate-modified polyisocyanate (A1), the molar ratio of the organic polyisocyanate (A) to the polymer polyol (B) is (A) / (B) = 3 to 20, and the resin. The acid value based on the carboxylic acid group is 50-100 mg KOH / g, and the chain extender (E) is An aqueous polyurethane dispersion, which is a mixture of a reamine compound and water.
(2) The aqueous polyurethane dispersion according to (1), wherein the polyamine compound in the chain extender (E) is diethylenetriamine and / or triethylenetetramine.
(3) The aqueous polyurethane dispersion according to either (1) or (2), wherein the gel fraction using methyl ethyl ketone in the solid content in the aqueous polyurethane dispersion is 80% or more.
(4) Organic polyisocyanate (A) is an allophanate modified from alkoxy poly (oxyalkylene) glycol (A1-1) and hexamethylene diisocyanate (A1-2) containing 50 mol% or more of oxyethylene groups in the repeating unit. The aqueous polyurethane dispersion according to any one of (1) to (3), which is an organic polyisocyanate mixture comprising a polyisocyanate (A1) and an alicyclic diisocyanate (A2).
(5) A water-based paint using the water-based polyurethane dispersion according to any one of (1) to (4).

  According to the present invention, it is possible to obtain an aqueous polyurethane dispersion excellent in water solubility and re-dissolvability in the obtained dry film and having characteristics that are insoluble in organic solvents such as MEK.

  Further, according to the present invention, it is also possible to obtain an aqueous paint using an aqueous polyurethane dispersion having the above-described characteristics.

  The present invention will be described in further detail.

<Organic polyisocyanate (A)>
The organic polyisocyanate (A) constituting the aqueous polyurethane dispersion of the present invention comprises an alkoxypoly (oxyalkylene) glycol (A1-1) containing 50 mol% or more of oxyethylene groups in the repeating unit and hexamethylene diisocyanate (A1- The allophanate-modified polyisocyanate (A1) obtained from 2) is contained. The allophanate-modified polyisocyanate (A1) substantially contains no isocyanurate group in the molecule. When the isocyanurate group is substantially contained, the viscosity of the organic polyisocyanate (A) increases, and it is necessary to reduce the viscosity such as dilution with an organic solvent during the production of the aqueous polyurethane dispersion.

  In the present invention, on the premise that the allophanate-modified polyisocyanate (A1) is contained, the organic polyisocyanate (A) is used in combination with an organic polyisocyanate other than the allophanate-modified polyisocyanate (A1). it can.

  Examples of organic polyisocyanates other than the allophanate-modified polyisocyanate (A1) include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, Aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, diphenyldimethylmethane diisocyanate, dibenzyl diisocyanate, naphthylene diisocyanate, phenylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, tetramethylene diisocyanate, HDI Except those corresponding to isocyanate (A1)), lysine diisocyanate, 2-methylpen 1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate, 2,2,4-trimethylhexahylene-1,6-diisocyanate, 2,4,4-trimethylhexahylene-1,6 -Aliphatic diisocyanates such as diisocyanates, isophorone diisocyanate, cyclohexyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated trimethylxylylene diisocyanate and the like. These organic diisocyanates can be used alone or in a mixture. Furthermore, modified products such as these adduct-modified products, carbodiimide-modified products, allophanate-modified products (excluding those described above), burette-modified products, uretdione-modified products, uretoimine-modified products, and isocyanurate-modified products can also be used.

  In the present invention, it is preferable to use the alicyclic diisocyanate as the organic polyisocyanate used in combination with the allophanate-modified polyisocyanate (A1). Among them, isophorone diisocyanate (hereinafter abbreviated as “IPDI”) is selected. And preferably used.

<Allophanate-modified polyisocyanate (A1)>
The allophanate-modified polyisocyanate (A1) used in the present invention comprises an alkoxypoly (oxyalkylene) glycol (A1-1) and HDI containing 50 mol% or more (preferably 70 mol% or more) of oxyethylene groups in the repeating unit. Obtained from (A1-2). Here, when the number of oxyethylene groups in the repeating unit in the alkoxypoly (oxyalkylene) glycol is less than 50 mol%, the water-dispersing ability of the resulting aqueous polyurethane dispersion (uniform dispersion stability in the aqueous polyurethane dispersion) is poor. It will be enough. In addition, when an organic diisocyanate other than HDI such as toluene diisocyanate (hereinafter abbreviated as “TDI”) or isophorone diisocyanate (hereinafter abbreviated as “IPDI”) is used, it has a ring structure (a kind of ladder structure). Therefore, the flexibility of the molecular skeleton is low, and the viscosity in the aqueous polyurethane dispersion tends to be high. For this reason, since an organic solvent is needed when manufacturing such an allophanate modified polyisocyanate, it is not preferable in this invention.

In the present invention, the isocyanate group content of the allophanate-modified polyisocyanate (A1) is preferably in the range of 5 to 15% by mass, and particularly preferably in the range of 8 to 13% by mass. The viscosity of the allophanate-modified polyisocyanate (A1) at 25 ° C. is preferably 1,000 mPa · s or less, and particularly preferably in the range of 100 to 800 mPa · s. When the isocyanate group content is less than 5% by mass or when the viscosity exceeds 1,000 mPa · s, the viscosity of the intermediate reactant during the reaction becomes high, and a large load is imposed on the production apparatus (of the production apparatus). Failure may occur). Moreover, when isocyanate group content exceeds 15 mass%, or when viscosity is too low, for example, less than 800 mPa * s, there is a possibility that the degree of allophanate modification in allophanate-modified polyisocyanate (A1) is insufficient. In many cases, the dispersibility of the resulting polyurethane dispersion (uniform dispersion stability in the aqueous polyurethane dispersion) tends to be insufficient.

The method for producing the allophanate-modified polyisocyanate (A1) is as follows. An excess amount of HDI (alkoxy poly (oxyalkylene) glycol / HDI = 1/5 to 1/20 (molar ratio) is preferred) is added to the alkoxy poly (oxyalkylene) glycol, and a urethanization reaction is performed. Next, an allophanatization catalyst such as a metal salt of a carboxylic acid is charged and an allophanatization reaction is performed. A reaction terminator such as phosphoric acid is charged to stop the allophanatization reaction, and unreacted HDI is removed by thin film distillation or the like to obtain the desired allophanate-modified polyisocyanate.

Preferred allophanatization catalysts are zirconium carboxylate, zirconyl carboxylate, and tin (divalent) carboxylate. Other allophanatization catalysts have a high degree of side reaction such as isocyanurate reaction and a low content of the desired allophanate-modified polyisocyanate. The polyisocyanate obtained by such a method has a large average number of functional groups, and gelation tends to occur during the production of a polyurethane resin. Specific products of the allophanate catalyst include Nikka Octix Zircon (manufactured by Nippon Chemical Industry Co., Ltd.).

When an allophanate-modified polyisocyanate is produced using the above-mentioned zirconium-based catalyst using an organic diisocyanate that is widely distributed in markets other than HDI, the allophanate-forming polyisocyanate is insufficient. It is difficult to obtain.

The alkoxypoly (oxyalkylene) glycol (A1-1) used for the allophanate-modified polyisocyanate (A1) is generally a compound having one hydroxyl group having 1 to 10 carbon atoms and 50 mol of ethylene oxide. % Or more of alkylene oxide is contained by ring-opening addition.

Here, examples of the initiator include saturated aliphatic alcohol compounds such as methanol, ethanol, propanol (including various isomers), butanol (including various isomers), pentanol (including various isomers), and allyl alcohol. Unsaturated fatty alcohol compounds such as phenol, phenolic compounds such as phenol, and araliphatic alcohols such as benzyl alcohol. In the present invention, an aliphatic alcohol having 5 or less carbon atoms is preferable, and a saturated aliphatic alcohol having 2 or less carbon atoms is particularly preferable in order to enhance the effect of imparting hydrophilicity. Further, the ethylene oxide content of the alkylene oxide is more preferably 70 mol% or more in consideration of the water dispersibility in the obtained polyurethane dispersion (uniform dispersion stability in the aqueous polyurethane dispersion).

The number average molecular weight of the alkoxy poly (oxyalkylene) glycol (A1-1) is preferably in the range of 200 to 2,000, particularly preferably in the range of 300 to 1,000. When the number average molecular weight of the alkoxy poly (oxyalkylene) glycol (A1-1) is less than 200, the effect of imparting hydrophilicity in the allophanate-modified polyisocyanate (A1) is small, and the water-dispersibility of the aqueous polyurethane dispersion using the same Insufficient. Further, when the number average molecular weight exceeds 2,000, the viscosity of the obtained allophanate-modified polyisocyanate (A1) is increased or solidified due to crystallization of the polyoxyethylene chain, and it is water-free without using a solvent It becomes difficult to produce a polyurethane dispersion.

<Polymer polyol (B)>
As the polymer polyol used in the present invention, polyester polyol, polyether polyol, polycarbonate polyol, or the like is used, and a normal one as a raw material of the polyurethane resin is used and is not particularly defined.

The polymer polyol used in the present invention has a number average molecular weight of 800 to 6,000 (more preferably a number average molecular weight of 800 to 2,500, and particularly preferably a more stable dispersibility of an aqueous polyurethane dispersion, In addition, those having a number average molecular weight of 1,000 to 2,000 are preferable from the viewpoint that productivity can be reliably obtained. Typically, polypropylene ethylene polyol (PPG), polytetramethylene ether glycol (PTG) And the like.

  More specifically, polyester polyols include phthalic acid, isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, succinic acid, malonic acid, adipic acid, 1,4-cyclohexyl dicarboxylic acid, maleic acid, fumaric acid, and other two types. Basic acid and the like, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, glycerin, trimethylolpropane, pentaerythritol, etc. From the polyols Polyester polyols obtained by the polycondensation reaction are employed. Further, cyclic esters such as ε-caprolactone, polyester amide polyols in which a part of the diol is changed to amines such as hexamethylene diamine and isophorone diamine can be used.

  Polyether polyols include the above diols, polyols, or these and amines such as ethylenediamine, propylenediamine, toluenediamine, metaphenylenediamine, diphenylmethanediamine, alkylene oxides such as ethylene oxide and propylene oxide, and methylglycidyl. A polyether polyol obtained by addition polymerization of an ether, an alkyl such as phenyl glycidyl ether or an aryl glycidyl ether, a cyclic ether such as tetrahydrofuran is used.

  As the polycarbonate polyol, a polycarbonate polyol obtained by a reaction of the diols or polyols with ethylene carbonate, diethyl carbonate, diphenyl carbonate or the like is used.

  In the aqueous polyurethane dispersion of the present invention, the molar ratio of the organic polyisocyanate (A) to the polymer polyol (B) is in the range of (A) / (B) = 3-20. Used as follows.

<Carboxyl group-containing low molecular weight glycol (C)>
As the carboxyl group-containing low molecular glycol (C) used in the present invention, a fatty acid having two terminal hydroxyl groups is preferably used. This fatty acid has two terminal hydroxyl groups as active hydrogen groups. For example, the active hydrogen groups at both ends react with isocyanate groups and are incorporated into the main chain of the prepolymer, and the free carboxyl groups are hydrophilic, so It works to increase dispersibility. Examples of the fatty acid compound having an active hydrogen group include dimethylolpropionic acid and dimethylolbutanoic acid having two terminal hydroxyl groups.

<Neutralizing agent (D)>
The neutralizing agent (D) used in the present invention neutralizes the carboxyl group of the carboxyl group-containing low molecular glycol incorporated in the urethane prepolymer main chain, and gives the effect of further improving the water dispersibility of the polyurethane resin. . Examples of the neutralizing agent (D) include ammonia, ethylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, triethanolamine, N-methyldiethanolamine, N-phenyldiethanolamine, monoethanolamine, dimethylethanolamine, diethyl Organic amines such as ethanolamine, morpholine, N-methylmorpholine, 2-amino-2-ethyl-1-propanol, alkali metals such as lithium, potassium and sodium, inorganic hydroxides such as sodium hydroxide and potassium hydroxide, etc. Can be mentioned.

<Chain extender (E)>
As the chain extender (D) used in the present invention, a polyamine compound having 3 or more active hydrogens is used. Examples of the compound having 3 or more active hydrogens include ethylenediamine (EDA), diethanolamine, diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine, and pentaethylenehexamine.

  In the present invention, it is preferable to select and use diethylenetriamine (DETA) and / or triethylenetetramine (TETA) as the chain extender (E).

  In the present invention, the chain extender (E) is used by mixing with water.

<Optional component>
The aqueous polyurethane dispersion in the present invention comprises the specific organic diisocyanate (A), the polymer polyol (B), the carboxyl group-containing low molecular glycol (C), the neutralizer (D), and the chain extender (E). If necessary, a viscosity reducing agent having an effect of promoting dispersion in water (solubility in water of 0.1 to 40% by mass and flash point of 50 ° C. or more) can be added. . Specific examples of the viscosity reducing agent include dipropylene glycol dimethyl ether (trade name: dimethylpropylene diglycol (abbreviation: DMM, solubility in water: 37.0 mass%, flash point: 65 ° C.), diethylene glycol dibutyl ether (commercial product). Name: Dibutyldiglycol, Abbreviation: DBDG, Solubility in water: 0.3 mass%, Flash point: 122 ° C., N-methylpyrrolidone (abbreviation: NMP, Solubility in water: (optional) mass%, flash point) : 91 ° C).

  Further, in the aqueous polyurethane dispersion in the present invention, a metal catalyst such as dibutyltin dilaurate or zinc naphthenate, or triethylenediamine, if necessary, for the purpose of accelerating the reaction in forming a polyurethane resin. A resin catalyst (urethanization catalyst) as a curing catalyst (polymerization catalyst) for urethane reaction, such as an amine catalyst such as N-methylmorpholine, can be used in combination.

  Furthermore, for the purpose of enhancing the desired physical properties of the aqueous polyurethane dispersion of the present invention and adding various physical properties, various additives include flame retardants, plasticizers, antioxidants, ultraviolet absorbers, fillers, Internal release agents, reinforcing materials, matting agents, conductivity imparting agents, charge control agents, antistatic agents, lubricants, and other processing aids can be used.

<Aqueous polyurethane dispersion>
As described above, the aqueous polyurethane dispersion of the present invention comprises an organic polyisocyanate (A), a polymer polyol (B), a carboxyl group-containing low molecular glycol (C), a neutralizer (D), and a chain extender (E). Is an aqueous polyurethane dispersion obtained by emulsifying a polyurethane resin obtained by reacting in water, and the organic polyisocyanate (A) is an alkoxy poly (oxyalkylene) glycol containing 50 mol% or more of oxyethylene groups in the repeating unit. It is an organic polyisocyanate (A) containing an allophanate-modified polyisocyanate (A1) obtained from (A1-1) and hexamethylene diisocyanate (A1-2), and is composed of the organic polyisocyanate (A) and the polymer polyol (B). The molar ratio is (A) / (B) = 3-20, and the carboxyl in the resin An acid value of 50~100mgKOH / g based on the group and in which chain extender (E) is characterized in that it is a mixture of water polyamine compound. The acid value is measured by, for example, a method disclosed in Japanese Industrial Standard JIS K5400.

<Method for producing aqueous polyurethane dispersion>
Next, a method for producing the aqueous polyurethane dispersion of the present invention will be described. The series of specific organic polyisocyanate (A), polymer polyol (B), and carboxyl group-containing low molecular glycol (C) are reacted. Under the present circumstances, you may interpose the viscosity reducing agent which has the effect which promotes the dispersion | distribution to the water mentioned as said arbitrary component, and a urethanization catalyst in a reaction system. Next, the carboxyl group is neutralized with a neutralizing agent (D) to obtain an isocyanate group-terminated prepolymer having a carboxylic acid amine salt and having improved water dispersibility. After the isocyanate group-terminated prepolymer is dispersed in water and emulsified, the aqueous polyurethane dispersion of the present invention is obtained by performing a chain extension reaction with the chain extender (E).

  In this case, the step of emulsifying by dispersing the isocyanate group-terminated prepolymer in water is a system in which water is pre-charged rather than adding and dispersing water in the system in which the isocyanate group-terminated prepolymer is preliminarily charged. It is preferable to add and disperse an isocyanate group-terminated prepolymer therein to emulsify.

<Water-based paint>
By using the aqueous polyurethane dispersion of the present invention, a dry film obtained (that is, a coating film or a film obtained by the aqueous polyurethane dispersion of the present invention) is excellent in water solubility and re-solubility, and is not limited to MEK or the like. It becomes possible to have characteristics that are insoluble in organic solvents.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is limited to these and is not interpreted. In the examples and comparative examples, “parts” and “%” indicate “parts by mass” and “mass%”, respectively, unless otherwise specified.

<Synthesis of allophanate-modified polyisocyanate>
Production Example 1:
863 g of “HDI (corresponding to (A1-2) of the present invention)” and “methoxypolyethylene glycol (number average molecular weight = 400) in a 1 L reactor equipped with a stirrer, a thermometer, a cooler and a nitrogen gas introduction tube. : Equivalent to (A1-1) of the present invention) ”and 0.2 g of“ zirconium 2-ethylhexanoate ”were charged and reacted at 90 ° C. for 2 hours in a nitrogen atmosphere. Next, 0.1 g of phosphoric acid ester “JP-508 (manufactured by Johoku Chemical Co., Ltd.)” was charged, and a stop reaction was performed at 50 ° C. for 1 hour. The isocyanate group content in the reaction product after the termination reaction was 40.2%. This reaction product was subjected to thin film distillation at 130 ° C. × 0.04 kPa to obtain an allophanate-modified polyisocyanate isocyanate “ALP-1” corresponding to (A1) of the present invention. The isocyanate content of “ALP-1” was 11.4%, the viscosity at 25 ° C. was 140 mPa · s, and the content of free diisocyanate (ie, “HDI”) was 0.1%. Further, when “ALP-1” was analyzed by FT-IR and ¹³ C-NMR, urethane groups and isocyanurate groups were hardly confirmed, and the presence of allophanate groups was confirmed.

<Synthesis of aqueous polyurethane dispersion>
Example 1:
Capacity with stirrer, thermometer, nitrogen seal tube and condenser: In a 3 L reactor, 200 g of “Polyol-1” (molar ratio = 1.0 equivalent) and 94 g of “DMPA” (molar ratio = 7. 0 equivalent), and mixed uniformly at 100 ° C. Thereafter, 176.4 g (molar ratio = 4.8 equivalent) of "ALP-1" obtained in Production Example 1 and 106.6 g (molar ratio = 4.8 equivalent) of "IPDI" were charged, respectively. Next, 0.05 g of “DOTDL” was charged, and stirred and reacted at 80 ° C. for 3 hours. Next, 95.2 g (corresponding to a molar ratio = 5.6) of “KOH” was charged to neutralize the carboxyl group to obtain an isocyanate group-terminated prepolymer. Thereafter, 1650 g of water was charged and emulsified. When emulsified, a chain extension reaction was carried out by adding amine water premixed with 46.8 g of water and 8.2 g of “DETA” (corresponding to a molar ratio = 0.8). When the presence of isocyanate groups was no longer confirmed by FT-IR, the reaction was terminated and cooled to 25 ° C., then 92.5 g of “MEK” was charged, and an aqueous polyurethane dispersion (corresponding to the aqueous polyurethane dispersion of the present invention) Got. Table 1 shows various performances of the aqueous polyurethane dispersion.
The “molar ratio” in the description is a molar ratio with respect to the polymer polyol (B), and other than the “solid content”, it is a mixed solution of 85% water and 15% MEK (both are The same in the following examples and comparative examples).

Examples 2-6, Comparative Examples 1-5:
According to the composition (molar ratio) shown in Table 1 and Table 2, each aqueous polyurethane dispersion was obtained based on the same method as in Example 1. Tables 1 and 2 show various performances and the like of each of these aqueous polyurethane dispersions.

The details of each abbreviation in Example 1, Table 1, and Table 2 are as follows.
“IPDI” (corresponding to (A2) of the present invention): Isophorone diisocyanate.
“Polyol-1” (corresponding to (B) of the present invention): Polypropylene glycol (average functional group number = 2, number average molecular weight = 2,000).
"DMPA" (corresponding to (C) of the present invention): 2,2-dimethylolpropionic acid.
"DOTDL": Dioctyltin dilaurate.
“KOH” (corresponding to (D) of the present invention): potassium hydroxide (33% aqueous solution).
"DETA" (corresponding to (E) of the present invention): diethylenetriamine.
“TETA” (corresponding to (E) of the present invention): triethylenetetramine.
"EDA" (corresponding to (E) of the present invention): ethylenediamine.
"MEK": methyl ethyl ketone.

<Evaluation of physical properties of coating film using aqueous polyurethane dispersion>
For each aqueous polyurethane dispersion obtained in the series of Examples and Comparative Examples, the aqueous polyurethane dispersion was cast on a plate glass and dried at 25 ° C. for 5 days to create a dry film having a thickness of 20 μm, The physical properties described below were measured. A series of results are also shown in Table 1 and Table 2 (“-” in Table 2 means “not measurable”).
<Tensile properties>
Tensile test (25 ° C .: 100% modulus, strength at break, elongation):
Tensile speed = 200 mm / min. A sample was prepared by punching with a No. 4 dumbbell of JIS K6301 (1995).
Tensile property measuring device: Tensilon UTA-500 manufactured by Orientec Co., Ltd.

<Evaluation of gel fraction using MEK in solid content in aqueous polyurethane dispersion>
For each of the aqueous polyurethane dispersions obtained in the series of Examples and Comparative Examples, the aqueous polyurethane dispersion was cast on a sheet glass and dried at 25 ° C. for 5 days, as in the above-described evaluation of the physical properties of the coating film. A dry film having a film thickness (a film comprising a solid content in an aqueous polyurethane dispersion) was prepared. About 1.5 g of this film was cut, and each was put in a cylindrical filter paper weighed in advance and weighed. This was immersed in MEK, boiled for 5 hours at the boiling point of MEK (80 ° C.), and then rinsed with MEK steam for 1 hour. After rinsing, the gel fraction was determined by drying and weighing. A series of results are shown in Table 1 and Table 2 together.

<Evaluation as a two-component water-based paint using a water-based polyurethane dispersion>
Examples 7-12:
Each of the aqueous polyurethane dispersions obtained in Examples 1 to 6 was used as a main agent, and self-emulsifying polyisocyanate (“Aquanate (registered trademark) 200” manufactured by Nippon Polyurethane Industry) was used together with a curing agent. Evaluation as a two-component water-based paint was carried out by the following method. In addition, the compounding ratio was made into main ingredient / hardening agent = 100/50 (mass ratio) in conversion of solid content. The evaluation results are shown in Table 3.

<Coating and curing conditions>
Base material: Aluminum plate (50 mm × 25 mm × 0.5 mm).
The coated surface is degreased with absorbent cotton soaked with MEK.
Application amount: 50 g / m2
Application temperature: 20 ° C.
Curing conditions: room temperature × 10 minutes + 50 ° C. × 24 hours + room temperature × 24 hours.
<Performance test>
Adhesion: Measured according to JIS K5400, cross-cut tape method.
Rubbing test: Absorbed cotton wool soaked with xylene 100 times and observed changes in the appearance of the film.
Flex resistance: Measured according to JIS K5400.
The diameter of the mandrel is 2mm.

As a result of a series of performance tests, each of the evaluations (Examples 7 to 12) as a two-component water-based paint using each of the aqueous polyurethane dispersions obtained in Examples 1 to 6 described above is as follows. Met.
<Adhesion>
“◯”: The film remaining rate is 80% or more.
<Rubbing test>
“◯”: Scratches etc. are hardly confirmed on the coating.
<Flexibility>
“◯”: No cracks or peelings are observed in the film.

The water-based polyurethane dispersion obtained by the present invention is particularly excellent in solvent resistance in various water-based polyurethane resin applications such as water-based paints and water-based adhesives, particularly in solids (and thus films) obtained by the water-based polyurethane dispersion. Can be suitably used in the field where is desired.

Claims (5)

A polyurethane resin obtained by reacting an organic polyisocyanate (A), a polymer polyol (B), a carboxyl group-containing low molecular glycol (C), a neutralizer (D), and a chain extender (E) is emulsified in water. In the aqueous polyurethane dispersion obtained,
An allophanate-modified polyisocyanate obtained from an organic polyisocyanate (A) obtained from an alkoxy poly (oxyalkylene) glycol (A1-1) and hexamethylene diisocyanate (A1-2) containing 50 mol% or more of oxyethylene groups in the repeating unit ( A1)
The molar ratio of the organic polyisocyanate (A) and the polymer polyol (B) is (A) / (B) = 3-20,
The acid value based on the carboxylic acid group in the resin is 50-100 mg KOH / g, and
An aqueous polyurethane dispersion, wherein the chain extender (E) is a mixture of a polyamine compound and water.   The aqueous polyurethane dispersion according to claim 1, wherein the polyamine compound in the chain extender (E) is diethylenetriamine and / or triethylenetetramine.   The aqueous polyurethane dispersion according to claim 1 or 2, wherein the gel fraction using methyl ethyl ketone in the solid content in the aqueous polyurethane dispersion is 80% or more.   An allophanate-modified polyisocyanate obtained from an organic polyisocyanate (A) obtained from an alkoxy poly (oxyalkylene) glycol (A1-1) and hexamethylene diisocyanate (A1-2) containing 50 mol% or more of oxyethylene groups in the repeating unit ( The aqueous polyurethane dispersion according to any one of claims 1 to 3, which is an organic polyisocyanate mixture comprising A1) and an alicyclic diisocyanate (A2). The water-based coating material using the water-based polyurethane dispersion in any one of Claims 1-4.