JPH04198361A - Low-temperature curable composition - Google Patents

Abstract

PURPOSE:To obtain a composition, curable at low temperatures in a short time and suitable as coatings for metals, plastics, concretes, ceramics, etc., by blending a polyurethane resin-based emulsion with a water-soluble amino resin and a catalyst. CONSTITUTION:A low-temperature curable composition is obtained by blending (A) a polyurethane resin-based emulsion in which carboxyl groups of a urethane polymer prepared by reacting (A1) an aliphatic and/or an alicyclic polyisocyanates (e.g. hexamethylene diisocyanate) with (A2) a polymer polyol (e.g. polyethylene glycol), (A3) an alpha,alpha-dimethylolmonocarboxylic acid and, as necessary, (A4) a chain extender and/or (A5) a polymerization terminator are neutralized with a primary and/or a secondary monoamines with (B) a water-soluble amino resin (e.g. ether type melamine resin) and (C) a catalyst (e.g. p- toluenesulfonic acid) at (50/50)-(95/5) weight ratio of the components (A)/(B) and (1/250)-(1/40) weight ratio of the components (C)/(B).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyurethane resin emulsion type low temperature curable composition. More specifically, the present invention relates to a low-temperature curable composition comprising a polyurethane resin emulsion, a water-soluble amino resin, and a catalyst.

[Prior Art] Conventionally, low-temperature curable compositions consisting of a polyurethane resin emulsion, a water-soluble amino resin, and a catalyst have been prepared by introducing an anionic functional group (particularly a carboxyl group) into the urethane molecule as a polyurethane resin emulsion component. ,
Compositions using emulsions produced by reaction with tertiary amines and self-emulsification are known.

(For example, Japanese Patent Publications Nos. 53-15874 and 52-3438) [Problems to be Solved by the Invention] However, the above composition has the problem that it is difficult to cure at low temperatures, and furthermore, it takes a long time to cure even at high temperatures. There was a problem.

[Means for Solving the Problems] The present inventors have devoted themselves to solving these problems, and as a result, they have arrived at the present invention. That is, the present invention comprises a polyurethane resin emulsion (A) and a water-soluble amino resin (
B) and a catalyst (C), in which (A) is an aliphatic and/or alicyclic polyisocyanate (a), a polymer polyol (b), and α,α-tumethylol monocarboxylic acid (c)
and, if necessary, a chain extender (d) and/or a polymerization terminator (e).
) is a low-temperature curable composition characterized by being an aqueous dispersion of a polyurethane resin neutralized with

In the present invention, the aliphatic and/or alicyclic polyisocyanate (a) is an aliphatic diisocyanate having 2 to 12 carbon atoms, such as hexamethylene diisocyanate (HDI), 2,2.4-)limethylhexane diisocyanate, Lysine diisocyanate, etc.; carbon number 4-18
Alicyclic diisocyanates, such as 1,4-cyclohexane diisocyanate (CDIL) isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MD I ), methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4 ,4'-diisocyanate,l,3
-Diisocyanatomethylcyclohexane (hydrogenated XDI)
etc.; aliphatic diisocyanates having an aromatic ring, such as quinrylene diisocyanate (XD I), tetramethylxylylene diisocyanate (TMID I), etc.;
Modified products of these diincyanates (carposiimide,
(uretidione, uretimine, biuret and/or isocyanurate modified product); and mixtures of two or more thereof. Among these, the preferred one is HD
I, IPDI, hydrogenated MDI and TMXD I.

When an aromatic polyisocyanate is used as (a), baking is not preferable because the coating film tends to yellow during curing, and the coating film is also susceptible to discoloration due to the influence of ultraviolet rays.

As the polymer polyol (b), (1) polyether polyols, such as those obtained by polymerizing or copolymerizing alkylene oxides (ethylene oxide, propylene oxide, butylene oxide, etc.) and/or heterocyclic ethers (tetrahydrofuran, etc.); Specifically, polyethylene glycol, polypropylene glycol, polyethylene-polypropylene (block or random) glycol, polyethylene-tetramethylene glycol (block or random), polytetramethylene ether glycol, polyhexamethylene ether glycol, etc.
Polyester polyols, such as aliphatic dicarboxylic acids (
succinic acid, adipic acid, sepacic acid, glutaric acid, azelaic acid, etc.) and/or aromatic dicarboxylic acids (isophthalic acid, terephthalic acid, etc.) and low molecular weight glycols (ethylene glycol, propylene glycol, 1,4-furandiol, 1 .6- Beef Sandiol, 3-methyl-
1,5-bentanediol, neopentyl glycol,
1,4-dihydroxymethylcyclohexane, etc.), specifically polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, polyethylene/butylene adipate diol, -3-methylpentane adipate diol,
polybutylene isophthalate diol, etc.; ■ polylactone polyol, such as polycaprolactone diol or triol, poly-3-methylvalerolactone diol, etc.; ■ polycarbonate polyol, such as polyhexamethylene carbonate diol; ■ polyolefin polyol, such as polybutadiene glycol. , polyisoprene glycol or its hydride; and mixtures of two or more thereof.

Among these examples of (b), preferred are ■~■, mixtures of two or more of ■~■, and ■~■
It is a mixture of one or more of these and a polyether polyol. The molecular weight of the polymer polyol (b) is usually 500 to 50
00, preferably 1000-3000.

α,α-dimethylol monocarboxylic acid (C) is a component used to introduce an anionic hydrophilic group to stably disperse polyurethane resin in water. Examples include acetic acid, α,α-dimethylolpropionic acid, α,α-dimethylolbutyric acid, and preferred is α,α-dimethylolpropionic acid.

The equivalent ratio of aliphatic and/or alicyclic polyisocyanate (a) to polymer polyol (b) is usually 3.0.
-0.3, preferably 2.0 to 0.8. If this equivalent ratio exceeds 3.0 or is less than 0.3, a high molecular weight product cannot be obtained and the physical properties of the coating film deteriorate. The amount of α, α-methylol monocarboxylic acid (C) is determined by the amount of carboxyl group (
-COOH) in the urethane polymer obtained by reacting (a) to (e), 0.3 to 5% by weight, preferably 0.5 to 5% by weight
It is 3% by weight. If it is less than 0.3% by weight, it is difficult to obtain a stable emulsion, and if it exceeds 5% by weight, the hydrophilicity of the polymer increases, resulting in a high viscosity of the emulsion and a decrease in the water resistance of the coating film.

When producing component (A), a chain extender (d) may be used if necessary. Examples of the chain extender (d) include low molecular weight polyols and polyamines. Examples of low-molecular polyols include the glycols listed as raw materials for the polyester polyols and their low molar alkylene oxide adducts (molecular weight less than 500); low molar alkylene oxide adducts of bisphenol (molecular weight less than 500); trihydric alcohols, such as glycerin. , trimethylolethane, trimethylolpropane, etc., and their low molar alkylene oxide adducts (molecular weight less than 500); and mixtures of two or more thereof. Polyamines include aliphatic polyamines such as ethylenediamine, N
-Hydroxyethylethylenediamine, tetramethylenediamine, hexamethylenediamine, diethylenetriamine, etc.; Alicyclic polyamines, such as 4,4'-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, inphorondiamine, etc.; Aliphatic polyamines having an aromatic ring , such as xylylene diamine, tetramethylxylylene diamine, etc.: Aromatic polyamines, such as 4,4
'-diaminodiphenylmethane, tolylene diamine, bendecine, phenylene diamine, etc.; and mixtures of two or more thereof. When the chain extender (d) is used in combination, the amount is usually 0.3 to 3
0% by weight, preferably 0.5-20% by weight.

Furthermore, if necessary, as a polymerization terminator (e), low molecular weight monoalcohols (methanol, butanol, cyclohexanol, etc.), monovalent alkylamines (mono- and diethylamine, mono- and di-butylamine, etc.), alkanolamines (mono- and di-butylamine, etc.), and di-ethanolamine, etc.) may also be used.

Primary or secondary monoamines (f) used for neutralizing carboxyl groups include ammonia; lower alkylamines such as methylamine, ethylamine, isopropylamine, n-butylamine, dimethylamine, diethylamine, diisopropylamine, diisopropylamine, -n-butylamine, etc.; Alicyclic amines, such as cyclohexylamine; Heterocyclic amines, such as morpholine, pyridine, etc.; Alkanolamines, such as monoethanolamine, jetanolamine, monoisopropanolamine, diisopropanolamine , methylethanolamine, methylisopropatoolamine, 2-amino-2-methylpropatool, etc.; or a mixture of two or more thereof. Among these, preferred are alkanolamines. The amount of monoamine (f) used is usually 0.00 equivalent per 1.0 equivalent of carboxyl group. s ~ 1.5 equivalents 1. Preferably it is 0.7 to 1.3 equivalents. If the amount is less than 0.5 equivalents, the hydrolysis resistance is poor and the emulsion is unstable; (2) If the amount exceeds 5 equivalents, the problem of heat yellowing occurs during curing.

To illustrate the method for producing the polyurethane resin emulsion (A) of the present invention, the above (a L (b), (c), if necessary, (d) and/or (e) are combined in one step in the presence or absence of an organic solvent). A carboxyl group-containing polyurethane resin is formed by reacting by a shot method or a multi-stage method, and then mixed with water after or while being neutralized in (f) to form a dispersion, and if necessary, the organic solvent is distilled off. By doing this, (A) is obtained. (A) usually has an average particle diameter of 0.0
It is an aqueous dispersion of self-emulsifying polyurethane resin with a diameter of about 0.01 to 1.0 μm. The above polyurethane formation reaction is usually 2
The reaction is carried out at a temperature of 0 to 150°C, preferably 50 to 120°C (however, when an amine is reacted, it is usually carried out at a temperature of 80°C or lower, preferably 0 to 70°C). In order to accelerate the reaction, amine-based or tin-based catalysts used in ordinary urethanization reactions (specifically dioctin tin simalate, dibutyltin dilaurate, stannous octylate, dibutyltin oxide, bis(tri-n-butyl In addition, when using an organic solvent, it is particularly preferable to use one that is water-soluble and has a boiling point of about the same level or lower as water (specifically, methanol, propatool,
Acetone, methyl ethyl ketone, tetrahydrofuran,
dioxane, and mixtures of two or more of these).

Water-soluble amino resin CB) includes ether type melamine resin, methylated melamine resin, ethylated melamine resin,
Examples include butylated melamine resin, methylolated melamine resin, methylated benzoguanamine resin, ethylated benzoguanamine resin, methylated urea resin, and the like. Among these amino resins, preferred are ether type melamine resin, methylol type melamine resin, and methylated melamine resin.

As the catalyst (C), acidic catalysts such as aromatic carboxylic acids (hydroxybenzoic acid, etc.), aromatic sulfonic acids (P-
) luenesulfonic acid, etc.), phosphoric acid esters (alkyl phosphates, hydroxyphosphates, etc.), maleic acid esters (alkyl maleates, hydroxymaleates, etc.), and the like. Preferred among these acidic catalysts are P-toluenesulfonic acid, butyl phosphate, and hydroxyphosphate. The blending ratio for obtaining the low-temperature curable composition of the present invention is usually (A)/(B): 5, expressed as the weight ratio of the resin content of each component.
0150-9515, preferably (mu)/(B)=70
If component (B) exceeds 50, the coating film becomes brittle, and if it is less than 5, curing becomes insufficient. Moreover, the range of (C)/(B): 1/250 to 1/40 is preferable.

A formulation example of the low temperature curable composition of the present invention is as follows. (% represents weight %) Usually preferably (A) (resin content) 50-95% 70-80% (B) (
Resin content) 5-50% 20-30% (C) 0-2%
0-1% dilution water remaining amount The remaining amount coating film thickness is usually 10-200 μm. Also, the baking temperature is usually 10
0℃~180℃1 Preferably 120℃~150℃
It is. The baking time is usually 5730 minutes, preferably 8~
It is 20 minutes.

[Example] The present invention will be further explained with reference to Examples below, but the present invention is not limited thereto. In the Production Examples, Examples, and Comparative Examples, "part" indicates parts by weight, and "r%" indicates weight %.

Production Example 1 Production of urethane resin emulsion (A-1) Polycaprolactone diol (molecular weight 2000) 88.
2 parts, poly-3-methylpentane adipate diol (
Molecular weight 2000) 88.2 parts, 1.4-butanediol 6.2 parts, trimethylolpropane 4.8 parts, α, α-
10.0 parts of dimethylolpropionic acid, IPDI 78.
6 parts and 120 parts of acetone were charged into a pressurized reaction vessel,
After reacting under pressure at 85° C. for 5 hours, 0 parts of 1,4-butanediol Ili and 150 parts of acetone were added, and the mixture was further reacted at the same temperature for 3 hours. Next, the reaction mixture was cooled to 40'C, neutralized by adding 8.8 parts of monoethanolamine, and mixed with 700 parts of ion-exchanged water. Then under reduced pressure for 70'
Acetone is distilled off at a temperature below C, solid content is 31.6%, viscosity is 2.
949 parts of urethane resin emulsion (A-1) at 50 cps/25°C and pH 3.4 was obtained.

Production Example 2 Production of urethane resin emulsion (A-2) Polycarbonate diol (molecular weight 2000) G9. l
Part i, poly-3-methylpentane adipate diol (
Molecular weight 2000) H, 6 parts, trimethylolpropane 2
．． 6 parts of ethylene oxide 2 mole adduct of bisphenol A (molecular weight 330), 37.7 parts, α,α-dimethylolpropionic acid, 8.8 parts, IPDI 92.0 parts, and acetone 120 parts were charged into a pressurized reaction vessel and heated to 85°. C for 5 hours, terminal NCO% = 2. [A prepolymer solution of i8 was obtained. Then, the mixture was cooled to 35° C., and a mixture consisting of 8.3 parts of hydroxyethylethylenediamine, 30 parts of Impropatol, and 120 parts of acetone was added, and the mixture was reacted for 1 hour.

Next, an ion exchanger containing 15.0 parts of jetanolamine
After mixing with 700 parts of water, the solvent was distilled off in the same manner as in Production Example 1, resulting in a solid content of 30.1% and a viscosity of 350 cps/25°C.
, pH 9.4 urethane resin emul') m 7 (
A-2) 997 parts were obtained.

Production Example 3 Production of urethane resin emulsion (A-3) Polyethylene isophthalate diol (molecular weight 2000
) [i[i, 1 part, neopentyl adipate diol (
Molecular weight: 2000) 6G, 1 part, 2.5 parts of trimethylolpropane, 38.8 parts of 2 mole adduct of bisphenol A with ethylene oxide, 8.2 parts of α,α-dimethylolpropionic acid, 102.0 parts of hydrogenated MD I and prepolymer solution from 7120 parts of acetate ([0% 2.72)
A mixture of 7.9 parts of N-hydroquinethylethylenediamine, 30 parts of Impropatol and 120 parts of acetone was added to the mixture, and the mixture was reacted for 1 hour at 30"C. After neutralization with 14.3 parts of jetanolamine, the ions were removed. It was mixed with 700 parts of exchanged water.The following procedure was repeated in the same manner as in Production Example 1 to obtain a solid content of 30.3%.
990 parts of a urethane resin emulsion (A-3) with a viscosity of 150 cps/25° C. and 1) H9.2 was obtained.

Production Example 4 Production of urethane resin emulsion (A-4) (comparison) Polycaprolactone diol (molecular weight 2000) 82.
9 parts, poly-3-methylpentane adipate diol (
Molecular weight 2000) 82.9 parts, 1.4-butanediol 3.6 parts, trimethylolpropane 4.8 parts, α, α-
13.3 parts of dimethylolpropionic acid, I P D I
91.9 parts and 120 parts of acetone were charged into a pressurized container and reacted at 85° C. for 6 hours to obtain a prepolymer with terminal NGO%=2.5%. Next, it was cooled to 30°C, and 9.0 parts of triethylamine (tertiary amine) and 1 part of acetone were added.
After adding a mixture of 20 parts and stirring for 0.5 hour,
Mix and emulsify 440 parts of ion-exchanged water, distill off acetone under reduced pressure at 40°C or below, add 3.0 parts of triethylamine, solid content 40.2%, viscosity 4200PS/25°C, p)
(s, s urethane resin emulsion (A-4) 72
Got 9 copies.

Next, low-temperature curable compositions of the present invention of Examples 1 to 5 and curable compositions of Comparative Examples 1 to 4 were prepared using the following formulations.

Example 1 Polyurethane resin emulsion (A-1) Solid content 100 parts Size 3
03 Solid content 20 parts (manufactured by Mitsui Cyanamid) p-) Luenesulfonic acid 0.3 parts Water
4
2 parts Example 2 Polyurethane resin emulsion (A-1) Solid content 100 parts Size 3
03 Solid content 33 parts (manufactured by Mitsui Cyanamid) 1)-) Luenesulfonic acid 0.3 parts Water

63 parts Example 3 Polyurethane resin emulsion (A-1) Solid content 100 parts Size 3
03 Solid content 50 parts (manufactured by Mitsui Cyanamid) p-Toluenesulfonic acid 0.3 parts Water
10
4 parts Example 4 Polyurethane resin emulsion (A-2) Solid content 100 parts Size 3
03 Solid content 33 parts (manufactured by Mitsui Cyanamid) p-Toluenesulfonic acid 0.3 parts Water
69
Part Example 5 Polyurethane resin emulsion (A-3) Solid content 100 parts Size 3
03 Solid content 33 parts (manufactured by Mitsui Cyanamid) p-Toluenesulfonic acid 0.3 parts Water
6
9 parts Comparative Example 1 Polyurethane resin emulsion (A-4) Solid content 100 parts Size 3
03 Solid content 20 parts (manufactured by Mitsui Cyanamid) 1)-) Luenesulfonic acid 0.3 parts Water
12
5 parts Comparative Example 2 Polyurethane resin emulsion (A-4) Solid content 100 parts Size 3
03 Solid content 33 parts (manufactured by Mitsui Cyanamid) 1)-) Luenesulfonic acid 0.3 parts Water
15
3 parts Comparative Example 3 Polyurethane resin emulsion (A-4) Solid content 1 (10 parts Sasumel 303 Solid content 50 parts (manufactured by Mitsui Cyanamid) p-) Luenesulfonic acid 0.3 parts Water
188
Part Comparative Example 4 Polyurethane resin emulsion (A-4) Solid content 100 parts Size 3
03 Solid content 33 parts (manufactured by Mitsui Cyanamid) p-Toluenesulfonic acid 0.3 parts Water
153
Part: Applying the curable compositions of Examples 1 to 5 and Comparative Examples 1 to 4 above on a tin plate (JIS G3303),
130°C ± 3°C 20 minutes (Note: Comparative example 4 only 170°C ±
A painted tin plate was prepared by baking at 3°C for 20 minutes (coating film thickness approximately 20 μm). The coating film performance test results are shown in Table 1.

Table-1 ・Using a high-grade pencil with a pencil hardness of JIS 5600G,
Measured according to S5400.

・Water resistance After immersing in water for 200 hours, the whitening and blistering state of the paint film was visually judged. (No change in O 6 Partial whitening x Overall whitening and blistering) - Solvent-resistant acetone was spotted on the paint film and changes in the state of the paint film were determined.

(0 No change △ Slight swelling × Partial dissolution) [Effects of the invention] As shown in the Examples and Comparative Examples, the composition of the present invention can be cured in a short time at low temperatures (~130"C~) It is possible to increase the speed of painting work.On the other hand, conventional compositions tend to have a curing delay effect, resulting in the need for curing at high temperatures and for a long time.The above effects Therefore, by blending pigments and additives, the low-temperature curable composition of the present invention can be used in paints and coach inks for metals, plastics, concrete, ceramics, etc. that require particularly low-temperature and fast-curing properties. It is useful for many applications.

Claims (1)

[Claims] 1. Consisting of a polyurethane resin emulsion (A), a water-soluble amino resin (B), and a catalyst (C), where (A) is an aliphatic and/or alicyclic polyisocyanate (a); High molecular polyol (b), α,α-dimethylol monocarboxylic acid (c), and if necessary a chain extender (
d) and/or the polymerization terminator (e), the carboxyl group in the urethane polymer is primary and/or
Alternatively, a low-temperature curable composition characterized in that it is an aqueous dispersion of a polyurethane resin neutralized with a secondary monoamine (f).