JPH11100425A - Water-based blocked polyisocyanate composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-based blocked polyisocyanate composition that gives coating layers excellent in weather resistance and cold curing properties, and a water-based coating composition containing the same. SOLUTION: This blocked polyisocyanate composition is derived from a precursor polyisocyanate composition having an average number of isocyanate groups of 4.5-20, a viscosity of 5,000-100,000 mPa. s at 25 deg.C, an isocyanate concentration of 2-20 wt.%, a diisocyanate cyclic trimer concentration of <=10 wt.%, an allophanate bonds/(allophanate bonds + urethane bonds) concentration of >=10 wt.%, and contains both a thermally dissociating blocked isocyanate group and a nonionic hydrophilic group in one molecule and has the following properties: (a) it is free from ionic group in its molecule, (b) the molar ratio of the polyether chain units/the isocyanate groups = 2/98-40/60, (c) the average functional group number of the blocked isocyanate = 3.5-18, (d) its number-average molecular weight = 1,000-10,000 and (e) the latent isocyanate concentration = 2-19 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an aqueous block polyisocyanate composition using a polyisocyanate composition obtained from an aliphatic or alicyclic diisocyanate, and an aqueous coating composition using the same.

[0002]

2. Description of the Related Art In recent years, water-based paints have attracted attention from the viewpoints of global environment, safety, hygiene and the like. It has come to be used for industrial products such as for cans and coil coatings from architectural exteriors. Further, there have been many proposals regarding one-part paints for automobiles, which require high quality such as weather resistance, chemical resistance, impact resistance, etc., as disclosed in JP-A-56-157358.
JP, JP-A-63-175079, JP-A-63-175079
A water-based paint is disclosed in, for example, JP-A-193968.
Many of the curing agents used here are alkyl etherified melamines.

Further, a coating film obtained from an isocyanate-crosslinked urethane-based coating material has extremely excellent abrasion resistance, chemical resistance, and stain resistance. By using a non-yellowing polyisocyanate using diisocyanate as a raw material, the weather resistance is further improved, and the demand is increasing. Accordingly, development of isocyanate-crosslinkable aqueous urethane-based paints has been actively conducted. When one-pack properties such as line paints are required, the isocyanate groups of the polyisocyanate are usually blocked with a heat-dissociable blocking agent and used as a blocked polyisocyanate.

As a technique for making a blocked polyisocyanate aqueous, for example, JP-A-52-59657 uses a surfactant to make a blocked polyisocyanate aqueous. JP-A-56-151753 discloses that polyethylene oxide containing a higher fatty acid having 7 to 26 carbon atoms is used, and the isocyanate group of polyisocyanate is blocked with sodium bisulfite to make block polyisocyanate aqueous. I have to.

Japanese Patent Application Laid-Open No. Sho 61 discloses a technique in which a specific polyoxyethylene, which is a hydrophilic group, is reacted with a polyisocyanate to prevent elution of a hydrophilic component, and is made aqueous using a high-speed stirring group.
No. 31,422. Japanese Patent Application Laid-Open No. 62-151419 discloses a technique for making a block of a polyisocyanate having a heat-resistant isocyanurate structure aqueous.
And JP-A-2-3465.

JP-A-62-151419 discloses that a polyoxyethylene group is added to a part of a polyisocyanate, and that a water-soluble polymer compound such as polyethylene glycol, a copolymer of ethylene oxide and propylene oxide is mixed. doing. JP-A-2-3465 discloses that
Hydroxycarboxylic acid imparts hydrophilicity.

However, when a crosslinked coating film is formed using these water-based blocked polyisocyanates, high-temperature baking is necessary, and there has been a limitation on the use of such materials as plastics having no heat resistance. Moreover, high-temperature baking requires large energy costs.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a water-based blocked polyisocyanate composition having excellent weather resistance and low-temperature curability, and a coating composition containing the same.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have reached the present invention. That is, the present invention is as follows. [1] A heat-dissociable blocked isocyanate group and a nonionic hydrophilic group are combined in one molecule, and (a) no ionic group is contained in the molecule; (b) polyether chain unit / isocyanate group = 2 / 98- 40/60 (mol / mol), (c)
3.5 to 1 average number of blocked isocyanate functional groups
8, (d) a number average molecular weight of 1,000 to 10,000,
(E) A water-based blocked polyisocyanate composition satisfying a latent isocyanate concentration of 2 to 19% by weight, and a precursor of the blocked polyisocyanate composition is a polyisocyanate composition A shown in the following (1). A water-based blocked polyisocyanate composition which can be dissolved or dispersed in water.

(1) Precursor polyisocyanate composition A
Is obtained by reacting at least one kind of aliphatic and / or alicyclic diisocyanate with a polyhydric alcohol, and has an average number of isocyanate group functional groups of 4.5 to 20, and a viscosity at 25 ° C of 5,000 to 100,000 m.
Pa · s, the isocyanate concentration is 2 to 20% by weight, the diisocyanate cyclic trimer concentration is 10% or less, and the allophanate bond / (allophanate bond + urethane bond) concentration is 10% or more. Substantially free of diisocyanates and solvents).

[2] The aqueous blocked polyisocyanate composition according to the above [1], wherein the polyhydric alcohol is a tri- to di-valent polyester and / or polyether. [3] An aqueous coating composition comprising a water-affinity polyol having a resin hydroxyl value of 10 to 200 mgKOH / g and the aqueous blocked polyisocyanate composition described in 1 or 2 above.

In the above, "substantially free of diisocyanate and solvent" refers to a state in which diisocyanate and solvent have been removed by using an industrial separation apparatus. They are less than 1% by weight. Hereinafter, the present invention will be described in detail. The diisocyanates used in the present invention are aliphatic and cycloaliphatic diisocyanates. As the aliphatic diisocyanate, one having 4 to 30 carbon atoms is preferable, and as the alicyclic diisocyanate, one having 8 to 30 carbon atoms is preferable.
Tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, lysine diisocyanate,
Examples thereof include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), 1,3-bis (isocyanatomethyl) -cyclohexane, and 4,4′-dicyclohexylmethane diisocyanate. Among them, 1,6-hexamethylene diisocyanate (hereinafter, referred to as HMDI) and isophorone diisocyanate (hereinafter, referred to as IPDI) are preferable from the viewpoint of weather resistance and industrial availability, and they can be used alone or in combination. May be.

[0013] The polyhydric alcohol used in the present invention is preferably a trihydric or higher alcohol, particularly preferably a trihydric to 20-valent, more preferably a trihydric to 10-hydric. Examples of the low molecular weight polyhydric alcohol include trimethylolpropane, glycerin, and pentaerythritol.

Examples of the high molecular weight polyhydric alcohol include aliphatic hydrocarbon polyols, polyether polyols, polyester polyols, epoxy resins, fluorine polyols and acrylic polyols. Specific examples of the aliphatic hydrocarbon polyols, for example,
Examples thereof include polybutadiene having a hydroxyl group at the terminal and a hydrogenated product thereof. Examples of the polyether polyols include, for example, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, a polyhydric alcohol such as sorbitol alone or a mixture thereof, and ethylene oxide, an alkylene oxide such as propylene oxide alone or a mixture thereof is added. And polyether polyols obtained by adding an alkylene oxide alone or a mixture to polyfunctional compounds such as ethylenediamine and ethanolamines, and polymerizing acrylamide and the like using these polyethers as a medium. And so-called polymer polyols, polytetramethylene glycols, and the like.

Examples of polyester polyols include succinic acid, adipic acid, sebacic acid, dimer acid,
Maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid and other dicarboxylic acids selected from the group of carboxylic acids alone or in combination with ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, glycerin, etc. Polyester polyol resins obtained by a condensation reaction with a polyhydric alcohol selected from the group alone or with a mixture, and, for example, polycaprolactone obtained by ring-opening polymerization of ε-caprolactone using a polyhydric alcohol And the like.

Examples of the epoxy resin include novolak type, β-methyl epichloro type, cyclic oxirane type, glycidyl ether type, glycol ether type, epoxy type of aliphatic unsaturated compound, epoxidized fatty acid ester type, and polyvalent carboxylic acid. Ester type, aminoglycidyl type,
Epoxy resins such as halogenated type and resorcinol type are exemplified.

Examples of the acrylic polyol include acrylates having active hydrogen such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxybutyl acrylate, and glycerol monoacrylates. Monoester or methacrylic acid monoester, trimethylolpropane acrylic acid monoester or methacrylic acid monoester alone or in mixture with methyl acrylate, ethyl acrylate, isopropyl acrylate, acrylic acid-n
Acrylates such as -butyl, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxypropyl methacrylate, methacrylic acid- Methacrylates having active hydrogen such as 4-hydroxybutyl, or methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, etc. And a mixture selected from the group consisting of methacrylic acid esters as an essential component, and unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid, acrylamide, N-methylolacrylamide, and diacetone acrylic acid. Unsaturated amides, such as amides and glycidyl methacrylate, styrene, vinyl toluene,
An acrylic polyol resin obtained by polymerizing in the presence or absence of a single or a mixture selected from the group of other polymerizable monomers such as vinyl acetate, acrylonitrile, and dibutyl fumarate is exemplified.

Preferred among these polyols are the above-mentioned polyester polyols and polyether polyols, particularly preferred are polycaprolactone-based polyester polyols and polypropylene-based polyether polyols, and more preferred are those having a number average molecular weight of 200 to 5
000. These can be used alone or
More than one kind may be used in combination.

When the diisocyanate is reacted with the polyhydric alcohol, the equivalent ratio of the isocyanate group of the diisocyanate to the hydroxyl group of the polyhydric alcohol is preferably 2/1 to 30/1. When the ratio is less than 2/1, the viscosity of the reaction solution after the reaction becomes high, and the equipment investment in the case of industrial production increases. When it exceeds 30/1, the productivity tends to decrease.
Preferably it is 5/1 to 20/1. Diisocyanate and polyhydric alcohol may be simultaneously charged in the reactor,
Only the diisocyanate may be charged first, and after reaching the predetermined temperature, the polyhydric alcohol may be added at once or in portions.

The diisocyanate is reacted with a polyhydric alcohol to convert at least a part of the formed urethane bond into an allophanate bond. In the reaction, a solvent may be used. In that case, it is preferable to use a solvent inert to the isocyanate group. Reaction temperature is 60
To 200 ° C, preferably 130 to 180 ° C. If the temperature is lower than 60 ° C., the reaction rate is low, and an increase in the average number of isocyanate group functional groups, which is presumed to be caused by the allophanation reaction, hardly occurs. If it exceeds 200 ° C., undesired side reactions such as coloring of the obtained polyisocyanate composition tend to occur.

The reaction time varies depending on the reaction temperature.
8 hours, preferably 2 to 6 hours. During the reaction,
A catalyst can also be used. As the catalyst, those having basicity are generally preferable. (A) For example, quaternary amine compounds such as tetraalkylammonium hydroxide and organic weak acid salts such as acetic acid and capric acid; Octylamine, 1,4-diazabicyclo (2,2,2) octane, 1,8-diazabicyclo (5,4,0) undecene-7, 1,5-diazabicyclo (4,3,0) nonene-5 and the like A catalyst which promotes the allophanation reaction of a tertiary amine compound, (c) a metal salt of an organic metal such as zinc, tin, lead, iron or the like such as a metal salt of acetylacetone such as zinc is effective.

The catalyst concentration is usually selected from the range of 10 ppm to 1.0% based on all isocyanate compounds charged to the reactor. Part of the urethane bond formed by the reaction between the diisocyanate and the polyhydric alcohol is converted to an allophanate bond, and the resulting polyisocyanate composition A has an allophanate bond. Conversion of urethane bonds to allophanate bonds is 10% or more, preferably 20% or more.
% Or more. If the value is less than 10%, the increase in the average number of isocyanate functional groups hardly proceeds, and the viscosity of the polyisocyanate composition may be too high.

The polyisocyanate composition A thus obtained has a diisocyanate cyclic trimer concentration of 10% or less. The concentration in this case is the ratio of the peak area of the diisocyanate cyclic trimer to the total peak area as measured by gel permeation chromatography. If the concentration of the diisocyanate cyclic trimer exceeds 10%, the number of isocyanate functional groups hardly increases, and when the diisocyanate cyclic trimer is imparted with hydrophilicity described later, the physical properties of the coating film may be reduced. That is, a component having a low number of isocyanate functional groups, such as a diisocyanate cyclic trimer, further decreases the number of isocyanate functional groups by imparting hydrophilicity, and as a result, crosslinkability decreases.

The yield is generally about 20% to 70% by weight. Remove unreacted diisocyanate and solvent,
The precursor polyisocyanate composition A having an allophanate bond used in the present invention is obtained. The average number of isocyanate functional groups in the polyisocyanate composition is the number of isocyanate functional groups that one molecule of polyisocyanate has statistically, and can be calculated from the number average molecular weight of the polyisocyanate composition and the isocyanate concentration by the following formula.

[0025]

(Equation 1)

The polyisocyanate composition A used in the present invention has an average isocyanate group functionality of 4.5 to 20. If the number of functional groups is less than 4.5, a good coating film cannot be obtained. When the number of functional groups exceeds 20, the mechanical properties of the coating film are inferior. Preferably it is 6-15. 25 of the polyisocyanate composition A thus obtained
The viscosity at ℃ is 5,000-100,000 mPa
S, isocyanate concentration of 2 to 20% by weight.

A compound having active hydrogen and an ethylene oxide unit is added to the obtained polyisocyanate composition A. This compound includes methanol, ethanol,
It is obtained by adding ethylene oxide to a monoalcohol such as butanol. The ethylene oxide content in the obtained compound is preferably at least 50% by weight, and the number average molecular weight is preferably from 200 to 1,000. This compound may include propylene oxide.

The addition amount of the compound having active hydrogen and ethylene oxide units to the polyisocyanate composition A (polyether chain units / isocyanate groups (mol / mol)) is 2 to 40% of the total isocyanate groups of the polyisocyanate composition. , Preferably 2 to 30%. 2%
If the amount is less than 40%, the water dispersibility of the polyisocyanate composition will decrease. The reaction between the compound and the polyisocyanate composition A can be performed using a solvent. The solvent used in this case is preferably inert to the isocyanate.

[0029] The reaction temperature is 40 to 150 ° C, preferably 60 to 120 ° C. If necessary, a basic compound such as a tin compound such as dibutyltin dilaurate may be used as the reaction catalyst. Polyisocyanate composition A in which the compound is not added to the obtained polyisocyanate composition A
Can also be mixed. In this case, the ratio of the compound added to all the isocyanates is preferably 2 to 40%.

The blocking agent is reacted with the isocyanate group of the polyisocyanate composition thus obtained to obtain a heat-dissociable blocked isocyanate group. Examples of the blocking agent used in the present invention include phenol-based, active methylene, mercaptan-based, acid amide-based, acid imide-based, imidazole-based, urea-based, oxime-based, amine-based, and imide-based compounds. Alternatively, they may be used as a mixture. Examples of more specific blocking agents are shown below.

1) Phenols: phenol, cresol, ethylphenol, butylphenol, etc. 2) Active methylene system; malonic acid diester (dimethyl malonate, diethyl malonate, di-n-butyl malonate, di-2-ethylhexyl malonate, methyl n-butyl malonate, ethyl n-butyl malonate, methyl malonate sec)
-Butyl, ethyl malonate sec-butyl, methyl malonate t-butyl, ethyl malonate t-butyl, methyl malonate diethyl, malonate dibenzyl, malonate diphenyl, malonate benzylmethyl, malonate ethylphenyl, malonate t -Butylphenyl, isopropylidene malonate), acetoacetate (methyl acetoacetate,
Ethyl acetoacetate, n-propyl acetoacetate, isopropyl acetoacetate, n-butyl acetoacetate, t-acetoacetate
-Butyl, benzyl acetoacetate, phenyl acetoacetate)
Acetylacetone and the like.

3) Mercaptans: butyl mercaptan, dodecyl mercaptan and the like. 4) Acid amides; acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam and the like. 5) acid imides; succinimide, maleic imide and the like. 6) Imidazoles; imidazole, 2-methylimidazole and the like.

7) Urea type: urea, thiourea, ethylene urea and the like. 8) Oxime type: formaldoxime, acetoaldoxime, acetoxime, methyl ethyl ketoxime, cyclohexanone oxime and the like. 9) Amine; diphenylamine, aniline, carbazole and the like. 10) Imines: ethyleneimine, polyethyleneimine and the like.

11) Bisulfite: sodium bisulfite and the like. 12) Pyrazoles; pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole and the like. 13) Triazole type; 1,2,4-triazole and the like. Of these, active methylene, oxime and acid amides are preferred, and more preferred are acetoxime, methyl ethyl ketoxime, malonic diester and acetoacetate, and in particular, one or more malonic diesters and one acetoacetate It is preferable to use the above in combination. The combination ratio is a malonic acid diester / molar ratio.
Acetoacetate ester is preferably 5/1 to 1/5, and when the value exceeds 5/1, crystallization of the blocked polyisocyanate may occur. Yellowing may occur.

The reaction between the polyisocyanate composition and the blocking agent can be performed with or without the presence of a solvent. When a solvent is used, it is preferable to use a solvent inert to isocyanate groups. During the blocking reaction,
As the catalyst, the above-mentioned reaction catalyst of diisocyanate and polyol can be used. When the used catalyst may adversely affect the properties of the paint, it is preferable to neutralize the catalyst with an acidic compound or the like. Examples of the acidic compound in this case include inorganic acids such as hydrochloric acid, phosphorous acid, and phosphoric acid, and sulfonic acids such as methanesulfonic acid, p-toluenesulfonic acid, p-toluenesulfonic acid methyl ester, and p-toluenesulfonic acid ethyl ester. Or a derivative thereof, ethyl phosphate, diethyl phosphate, isopropyl phosphate, diisopropyl phosphate, butyl phosphate, dibutyl phosphate, 2-ethylhexyl phosphate, di (2-ethylhexyl) phosphate, isodecyl phosphate, diisodecyl phosphate, oleyl acid phosphate, tetracosyl acid phosphate, There are ethylene glycol acid phosphate, butyl pyrophosphate, butyl phosphite and the like, and two or more of these may be used in combination.

The blocking reaction is generally carried out at -20 to 150.
C., preferably from 0 to 100.degree. If the temperature exceeds 100 ° C, a side reaction may occur,
On the other hand, if the temperature is too low, the reaction rate becomes low, which is disadvantageous. As described above, the concentration of the isocyanate group reacted with the blocking agent is referred to as a latent isocyanate concentration, and the number of isocyanate functional groups statistically reacted with the blocking agent in one molecule is referred to as the average number of blocked isocyanate functional groups.

The reaction between the isocyanate group and the blocking agent, and the reaction between the isocyanate group and the ethylene oxide adduct,
Either one can be prioritized, or they can be performed simultaneously. The water-based blocked polyisocyanate composition of the present invention thus obtained has the following characteristics. (A) No ionic group is contained in the molecule. (B) polyether chain unit / isocyanate group = 2/9
8 to 40/60 (mol / mol). (C) The average number of blocked isocyanate functional groups is 3.5 to
18. (D) The number average molecular weight is 1,000 to 10,000. (E) The latent isocyanate concentration is 2 to 19% by weight.

Further, an anionic, cationic, nonionic or amphoteric surfactant can be added according to the purpose. Specific examples of the surfactant include, for example, carboxylic acids, sulfonic acids, sulfates, phosphates, anionics such as sodium and potassium of polymerizable polymers, quaternary ammonium salts, cationics such as polyethyleneamine derivatives, Nonionic surfactants such as ethers, esters, ester ethers, and nitrogen-containing surfactants, and zwitterionic surfactants such as carboxybetaine, aminocarboxylic acid, sulfobetaine, aminosulfate, and imidazoline can be used.

In the present invention, a monohydric alcohol compound is preferably contained in order to improve storage stability.
Examples of the monohydric alcohol compound include aliphatic, alicyclic,
There are aromatic and the like, and aliphatic is preferable. 1-20 carbon atoms
Are preferred, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, se
c-butanol, tert-butanol, 2-methyl-
1-propanol, n-amyl alcohol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-2-butanol And saturated alcohols such as 2,2, -dimethyl-1-propanol and ether alcohols such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol and 3,6-dioxa-1-heptanol. The amount added is 0.2 to 10 based on the heat dissociable blocked isocyanate group.
Double molar amounts are preferred.

The low-temperature curable water-based blocked polyisocyanate composition thus prepared is mixed with a water-philic polyol to form a main component of the water-based coating composition. As the water-affinity polyol used in the present invention, it is generally possible to use any water-soluble polyol as long as it is used for water-based coatings.
It may be an amphoteric ion type or a non-ionic type. Alkyd, polyester, epoxy,
There are fluorine type and acrylic type. The polyol has a resin hydroxyl value of 10 to 200 mgKOH / g and is dissolved or dispersed in a dispersion medium containing water as a main component. When the resin hydroxyl value is less than 10 mgKOH / g, the density of urethane crosslinks due to the reaction with the isocyanate component decreases, and the physical properties of the present invention cannot be achieved. When the resin hydroxyl value exceeds 200 mgKOH / g, Conversely, the crosslinking density increases, and the mechanical properties of the coating film decrease, which is not preferable.

The soluble polyol preferably has a number average molecular weight of 2,000 to 100,000. For example, JP-A-63-295680, JP-A-63-1750
No. 59, JP-A-62-216671, JP-A-2-191692, and the like disclose the manufacturing method. The dispersion type polyol is a latex containing a hydroxyl group, and its production method is disclosed in, for example, JP-A-56-157358.

The fluorine polyol which is a fluorine-containing copolymer having a hydroxyl group is disclosed in JP-A-57-3410.
7, JP-A-61-231044, and JP-A-Hei-3
JP-A-37-252 discloses a manufacturing method thereof. In the aqueous coating composition of the present invention, the equivalent ratio of the thermally dissociated blocked isocyanate group to the hydroxyl group of the water-affinity polyol is usually set to 10: 1 to 1:10.

As the curing agent, a curing agent other than the blocked polyisocyanate, for example, a melamine-based curing agent can be used in combination. Representative examples of the melamine-based curing agent include hexamethoxymethylolmelamine, methyl-butyletherified melamine, and the like. Also, if necessary, an antioxidant, an ultraviolet absorber, a pigment, a metal powder pigment such as aluminum, a crosslinking accelerator such as an organic metal compound such as dibutyltin dilaurate, a leveling agent, a rheology control agent, and a solvent are added. Is also good.

Usually, an aqueous coating composition is obtained by mixing a water-affinity polyol, a curing agent, additives and the like, adding a medium containing water as a main component, and adjusting the coating viscosity according to the coating method. . The water-based paint adjusted in this way is applied to metals, plastics, inorganic materials, and the like by a method such as spray coating, roll coating, shower coating, or dip coating, and is also useful as a chipping-resistant coating, a precoat metal coating, and the like.

The low-temperature curable aqueous block polyisocyanate composition of the present invention may be used in addition to paints, inks, adhesives,
Inorganic materials such as fibers, films, ceramics, paper, wood,
It is also useful as a modifier such as a resin, a surface treatment agent, and a binder.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. Parts and% are based on weight. The evaluation was performed as follows. (Measurement of number average molecular weight) The number average molecular weight was measured by gel permeation chromatography (hereinafter referred to as G
(Referred to as PC) is the number average molecular weight based on polystyrene measured. Equipment: Tosoh Corporation HLC-802A Carrier: tetrahydrofuran Detection method: differential refractometer (concentration of diisocyanate cyclic trimer) Expressed as the peak area% of the molecular weight (for example, 504 in the case of HMDI) corresponding to the diisocyanate cyclic trimer obtained by the GPC measurement. .

(Measurement of Allophanate Bond Concentration) Using FT-NMR “FX90Q” from JEOL, using acetone-d6 as a solvent, the result of H-NMR measurement showed that allophanate bond / (allophanate bond + urethane bond). The values obtained were indicated by ◎ for 0.9 or more, ○ for less than 0.9 and 0.1 or more, and x for less than 0.1.

(Measurement of Viscosity) The viscosity was measured at 25 ° C. using an Emira type rotational viscometer. (Gel fraction) The value of the weight of the undissolved portion when the cured coating film was immersed in acetone at 20 ° C. for 24 hours with respect to the weight before immersion was calculated.

(Evaluation of Water Dispersibility of Block Polyisocyanate Composition) The block polyisocyanate composition and pure water were mixed at a weight ratio of 2:10, and the state of the solution thereafter was visually observed. "Good" when the mixture is homogeneous and free of sediment
Was evaluated.

[0050]

[Production Example 1] (Production of polyisocyanate composition) Stirrer, thermometer,
The atmosphere in the four-necked flask equipped with a reflux condenser, a nitrogen blowing tube, and a dropping funnel was set to a nitrogen atmosphere, and HMDI was set to 600.
Part, polyether polyol which is a tetrahydric alcohol (trade name “ADEKA NEW POLYOL WR-474” by Asahi Denka)
169 parts were charged, and the temperature in the reactor was maintained at 120 ° C. for 5 hours with stirring. The reaction solution temperature was lowered, and unreacted HMDI was removed using a thin film evaporator.

The molecular weight of the reaction product was measured by GPC, the concentration of allophanate bond was measured by H-NMR, and the concentration of isocyanate was measured by titration to confirm that the polyisocyanate composition of the present invention was formed. did.
The viscosity at 25 ° C. of the obtained polyisocyanate composition was 20,000 mPa · s, and the isocyanate concentration was 1
3.2%, number average molecular weight is 1,690, isocyanate average number of functional groups is 5.3, diisocyanate cyclic 3
The monomer concentration was 1.7%. The allophanate bond concentration of the polyisocyanate composition was ○.

[0052]

Production Examples 2 to 5 and Reference Production Examples 1 and 2 Using the same apparatus as in Production Example 1, the reaction was carried out under the reaction conditions shown in Table 1, and unreacted HMDI was removed in the same manner as in Production Example 1. . Table 2 shows the physical properties of the polyisocyanate composition.

[0053]

Reference Production Example 3 The same apparatus as in Production Example 1 was charged with 600 parts of HMDI and 11 parts of 1,3-butanediol, and the temperature inside the reactor was kept at 80 ° C. for 2 hours under a nitrogen atmosphere.
Thereafter, the temperature in the reactor was maintained at 60 ° C., tetramethylammonium capryate was added as an isocyanuration reaction catalyst, and when the yield reached 28%, phosphoric acid was added to stop the reaction. After filtering the reaction solution, unreacted HMDI was removed using a thin film evaporator. Table 2 shows the physical properties of the obtained polyisocyanate composition.

[0054]

Example 1 (Production of Aqueous Blocked Polyisocyanate Composition) A four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen blowing tube, and a dropping funnel was set to a nitrogen atmosphere, and obtained in Production Example 1. 100 parts of the obtained polyisocyanate composition, 19 parts of methoxypolyethylene glycol having a molecular weight of 600 (trade name "UNIOX M600" of NOF Corporation) (reacts with 10% of all isocyanate groups of polyisocyanate), and propylene glycol monomethyl ether acetate 47 as a solvent And maintained at 80 ° C. for 7 hours. The temperature in the reactor was lowered to 50 ° C., and 26 parts of methyl ethyl ketoxime was added dropwise, and it was confirmed that the characteristic absorption of the isocyanate group in the infrared spectrum had disappeared.

An aqueous blocked polyisocyanate composition solution having a resin solid content of 75% by weight was obtained. When the aqueous dispersibility of the obtained aqueous block polyisocyanate composition was evaluated, it was good.

[0056]

Examples 2 to 7 (Production of aqueous block polyisocyanate composition) Table 3
The procedure was performed in the same manner as in Example 1 except for the above. Table 3 shows the results.

[0057]

Comparative Examples 1-3 Using the polyisocyanate composition obtained in Reference Production Example 1, the procedure was carried out in the same manner as in Example 1 except for the conditions shown in Table 4. Table 4 shows the results.

[0058]

Production Example 6 (Production of water-affinity polyol) 100 parts of isopropyl alcohol was charged into a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel, and the temperature was raised to 80 ° C. 22 parts of styrene, 22 parts of methyl methacrylate, 21 parts of n-butyl acrylate, 24 parts of 2-hydroxyethyl methacrylate, 11 parts of acrylic acid, and 3 parts of azobis (isobutyronitrile) were charged into a dropping funnel, and then 3.5. It was dropped into the flask over time.

After the dropwise addition, the mixture was kept for 2 hours to give a resin hydroxyl value of 1
A water-affinity polyol having an acid value of 86 mgKOH / g and an acid value of resin of 86 mgKOH / g was obtained.

[0060]

Examples 8 to 14 (Aqueous coating composition) A water-affinity polyol obtained in Production Example 6 neutralized with dimethylethanolamine, and an aqueous block polyisocyanate composition obtained in Examples 1 to 7 With an isocyanate group / hydroxyl group equivalent ratio of 1 /
1 was mixed. Further, water was added, and the paint viscosity was changed to Ford Cup No. 4 was adjusted to 30 seconds. This paint is applied to an applicator, and 130 and 10
Cured at 0 ° C. for 30 minutes. Table 5 shows the coating film baking conditions and the evaluation results.

[0061]

Comparative Examples 4 to 6 The same procedures as in Example 6 were carried out except that the aqueous block polyisocyanates obtained in Comparative Examples 1 to 3 were used. Table 6 shows the results.

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

[Table 3]

[0065]

[Table 4]

[0066]

[Table 5]

[0067]

[Table 6]

[0068]

The aqueous coating composition using the water-based blocked polyisocyanate composition of the present invention is an aqueous one-pack type thermosetting coating composition having excellent curability and weatherability.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09D 5/00 C09D 5/00 A 175/04 175/04

Claims (3)

[Claims] 1. A thermodissociable blocked isocyanate group and a nonionic hydrophilic group are combined in one molecule, (a) no ionic group in the molecule, and (b) polyether chain unit / isocyanate group = 2 / 9
8 to 40/60 (mol / mol), (c) the average number of blocked isocyanate group functional groups is 3.5
An aqueous block polyisocyanate composition that satisfies (d) a number average molecular weight of 1,000 to 10,000, and (e) a latent isocyanate concentration of 2 to 19% by weight. An aqueous block polyisocyanate composition which can be dissolved or dispersed in water, wherein the precursor of the product is a polyisocyanate composition A shown in the following (1). (1) A precursor polyisocyanate composition A is obtained by reacting at least one kind of aliphatic and / or alicyclic diisocyanate with a polyhydric alcohol, and has an average number of isocyanate group functional groups of 4.5 to 20, 25 ° C. At 5,000-100,000m
Pa · s, the isocyanate concentration is 2 to 20% by weight, the diisocyanate cyclic trimer concentration is 10% or less, and the allophanate bond / (allophanate bond + urethane bond) concentration is 10% or more. Substantially free of diisocyanates and solvents). 2. The aqueous blocked polyisocyanate composition according to claim 1, wherein the polyhydric alcohol is a tri- to tri-valent polyester and / or polyether. 3. A resin hydroxyl value of 10 to 200 mg KOH.
/ G of a water-affinity polyol and the aqueous blocked polyisocyanate composition according to claim 1 or 2.