JPH08311394A - Aqueous polyester resin varnish composition - Google Patents

Abstract

PURPOSE: To obtain the subject composition by dissolving a polyester resin comprising an aromatic polyfunctional carboxylic acid, an aliphatic acid, an end hydroxyl group-containing polyalkanedienediol, etc., in an aqueous medium containing a base, excellent in coating workability, dispersion stability and coating film performance. CONSTITUTION: This varnish composition is obtained by dissolving a polyester resin comprising the whole reactive components to form a polyester chain, based on the total amount, composed of (A) 10-60wt.% of an aromatic polyfunctional carboxylic acid, (B) 0-30wt.% of a >=6C aliphatic acid or oils and fats containing it, (C) 1-30wt.% of an end hydroxyl group-containing polyalkanedienediol or a hydrogenated polyalkanedienediol having 5-50 average degree of polymerization alone or its mixture and (D) the rest of a reactive component except the components A, B and C, having 10-100 acid value, 30-200 hydroxyl number, <=1 water tolerance and 10,000-200, 000 weight-average molecular weight in an aqueous medium containing a base in which a divalent and a polyvalent basic metal hydroxides amount to 5-20% neutralization equivalent and which is in an amount to neutralize >=50% of the total of carboxyl groups.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION The present invention relates to an aqueous polyester resin varnish for producing an aqueous coating in combination with a crosslinking agent such as a melamine resin.

In recent years, there has been an increasing interest in the use of water-based paints from the viewpoint of environmental protection, resource saving and energy saving.
When a polyester resin containing an alkyd resin is used as a vehicle resin for an aqueous paint, a carboxyl group of the resin is neutralized with a base to be water-soluble, and then dissolved or dispersed in an aqueous medium to prepare an aqueous varnish. However, it is known that the viscosity of this aqueous varnish increases in proportion to the neutralization rate of the resin, and if the neutralization rate is kept low in order to keep the viscosity of the varnish low, the dispersion stability of the varnish becomes unsatisfactory. Further, even in the case of an aqueous varnish, as in the case of the solvent varnish, the viscosity increases in proportion to the molecular weight of the resin, particularly the weight average molecular weight. In order to increase the resin solid content, the molecular weight of the resin itself must be decreased. However, in this case, satisfactory coating performance cannot be obtained. In the aqueous paint prepared from the aqueous polyester resin varnish in this way,
It was very difficult to simultaneously satisfy the coating workability, dispersion stability and coating film performance of the paint.

Aqueous paints using ordinary water-based resin varnishes follow Newton's viscosity law, so if the non-volatile content of the paint is increased to a high viscosity that does not cause sagging at the time of application, the paint viscosity by spraying etc. will also be high. Therefore, there is a problem that atomization cannot be sufficiently performed. In contrast,
For non-Newtonian fluids, where the apparent viscosity decreases with increasing shear rate, the apparent viscosity is low enough for atomization in the high shear rate region, such as during spraying, and low shear rate, such as during coating. In the area, it becomes high enough to prevent sagging. Casson proposed that the viscous behavior of paints fit well with the equation:

[0004]

[Equation 1]

Here, η ∞ = residual viscosity (viscosity when the shear rate D is infinite) S ₀ = yield value (shear stress when extrapolating the shear rate to zero) The higher the yield value, the more sagging. It is known that it is less likely to occur and that the lower the residual viscosity is, the easier it is to atomize. Therefore, the viscosity is measured at each shear rate, η ^1/2 and D ^1/2 are plotted, and the residual viscosity and yield value are calculated according to the above formula. Can be asked. The residual viscosity and yield value thus obtained can be considered as an index of the atomization property and sag property of the coating material.

DISCLOSURE OF THE INVENTION In the present invention , based on the total amount of all reaction components forming a polyester chain, (a) aromatic polycarboxylic acid 10
To 60% by weight, (b) fatty acid having 6 or more carbon atoms or fats and oils containing it, 0 to 30% by weight, (c) average degree of polymerization 5 to 50
Hydroxyl group-terminated polyalkadiene diol alone,
Hydrogenated polyalkadiene diol alone or 1 to 30% by weight of a mixture thereof, (d) the balance is the above (a), (b),
It comprises a reaction component other than (c), has an acid value of 10 to 100, a hydroxyl value of 30 to 200, a water tolerance of 1 or less, a weight average molecular weight of 10,000 to 200,000, and is dissolved in an aqueous medium containing a base or Provided is a dispersed aqueous polyester resin varnish composition. The improvements according to the invention are:
The aqueous medium in which the resin is dissolved or dispersed contains an amount of a base that neutralizes at least 50% of the total carboxyl groups of the resin, and 5 to 20% of the neutralization equivalent of the base is a divalent or higher valent basic metal hydroxide. Things occupy.

As described above, by using a divalent or higher valent basic metal hydroxide such as calcium hydroxide, magnesium hydroxide or barium hydroxide as a part of the neutralizing base, the varnish and the coating material containing the varnish can be obtained. It has a low viscosity in the high shear rate region such as spray coating, but has a high viscosity in the low shear rate region such as coating, and exhibits a shear rate-dependent pseudoplastic viscosity. This makes it possible to simultaneously satisfy the coating workability of the coating material, the dispersion stability, and the coating film performance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As is well known, polyester resins are produced by condensing polyhydric carboxylic acids and polyhydric alcohols as essential ingredients. Other reaction components can include minor proportions of monocarboxylic acids, hydroxycarboxylic acids, lactones, etc., and alkyd resins include drying oils or semi-drying oils and their fatty acids.

The polyester resin of the present invention has a content of 10 to 60%, preferably 2%, based on the total weight of all reaction components.
It must contain 0 to 50%, especially 30 to 40% of aromatic polycarboxylic acids. Examples thereof are phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic anhydride, tetrabromophthalic anhydride, tetrachlorophthalic anhydride, pyromellitic dianhydride, but isophthalic acid, terephthalic acid, trimellitic anhydride are preferred. . If too much is used, the viscosity of the resin will increase during water solubilization or dispersion.

As the remaining acid component, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, 1,4- and 1,3-cyclohexanedicarboxylic acid, maleic anhydride, succinic anhydride, adipic acid, sebacic acid, azelaic acid, etc. There is. As mentioned previously, small proportions of hydroxycarboxylic acids such as 4-hydroxybenzoic acid, hydroxypivalic acid, 12-hydroxystearic acid and the like, and monocarboxylic acids such as benzoic acid, t-butylbenzoic acid and the like may also be included.

The polyester resin of the present invention contains, as a polyhydric alcohol component, 1 to 30%, preferably 2 to 20%, and especially 3 to 15% of a hydroxyl group-terminated polyalkadiene diol alone, based on the total amount of all reaction components. It must contain hydrogenates alone or in mixtures. These diols are derived from conjugated alkadiene oligomers or polymers with a degree of polymerization of 5 to 50. The molecular weight is 1,
It is preferably in the range of 000 to 4,000, particularly 1,500 to 3,000. 1,4-polyisoprene diol, 1,4- and 1,2-polybutadiene diol, hydrogenated products thereof are preferred. As a commercial product, Epol (hydrogenated polyisoprene diol, molecular weight 186
0, average degree of polymerization 26, Idemitsu Petrochemical Co., Ltd., PIP
(Polyisoprene diol, molecular weight 2,200, average degree of polymerization 34, manufactured by Idemitsu Petrochemical Co., Ltd.), Polytail HA
(Hydrogenated polybutadiene diol, molecular weight 2,200,
Average degree of polymerization 39, Mitsubishi Kasei Co., Ltd., Polytail H
(Hydrogenated polybutadiene diol, molecular weight 2,350,
Average degree of polymerization 42, manufactured by Mitsubishi Kasei Co., Ltd., R-45H
T (polybutadiene diol, molecular weight 2,270, average degree of polymerization 42, manufactured by Idemitsu Petrochemical Co., Ltd.) and the like. The use of these diols as part of the polyhydric alcohol component results in high molecular weight polyester resins that give relatively low viscosities at high degrees of neutralization. However, if it is used too much, a satisfactory coating hardness cannot be obtained.

As the remaining polyhydric alcohol component, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and 2,2- Diethyl-1,3-propanediol, neopentyl glycol, 1,9-nonanediol, 1,4-cyclohexanedimethanol, hydroxypivalic acid neopentyl glycol ester, 2-butyl-2-ethyl-1,3
-Propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethylpentanediol, hydrogenated bisphenol A and other diols, and trimethylolpropane, trimethylolethane, glycerin, pentaerythritol and other three There are polyols with a valency or higher.

In the case of alkyd resins, up to 30%, preferably up to 25%, especially 10 to 10% of the total weight of all reaction components.
It must contain 20% of fatty acids having 6 or more carbon atoms or fats and oils containing them. Examples of these fats and oils components are castor oil, linseed oil, dehydrated castor oil, tung oil, safflower oil, soybean oil, tall oil, coconut oil, palm kernel oil and their fatty acids. Palm oil and palm kernel oil are preferred.

As a reaction component other than the above, Cardura E
There are monoepoxide compounds such as (trade name: manufactured by Ciel Kagaku) and lactones. Lactones form ring-opening additions to the polyester chains of polyhydric carboxylic acids and polyhydric alcohols to themselves form polyester chains. Examples thereof include β-propiolactone, dimethylpropiolactone, butyrolactone, γ-valerolactone, ε-caprolactone, γ-caprolactone, γ-caprylolactone, crotlactone, δ-valerolactone, and δ-caprolactone. However, ε-caprolactone is preferred. Its amount is 3 to 30%, preferably 5 to 20%, in particular 7 to 15% of the total weight of all reaction components.

For the synthesis of polyester, the above reaction components are used in a conventional manner in a nitrogen stream at, for example, 150 to 250 ° C. and 4-1.
It can be performed by heating for 0 hours and condensation. In that case, as the catalyst, known catalysts such as dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, and tetraisopropyl titanate can be used. The reaction components may be added all at once, or may be added in several batches.

The molar ratio of the reaction components and the reaction conditions are such that the polyester resin obtained has an acid value of 10 to 100, preferably 20 to 50, and a hydroxyl value of 30 to 200, preferably 5.
0-150, weight average molecular weight 10,000-200,
It should be adjusted to reach 000, preferably 25,000 to 160,000.

The polyester resin of the present invention contains 0.5% of the total amount of carboxyl groups contained in the resin, that is, 0.5% with respect to the total amount of carboxyl groups.
Dissolved or dispersed in an aqueous medium containing .about.1.2 equivalents, preferably 0.7 to 1.0 equivalents of base.

According to the invention, the neutralization equivalent of the base is 5 to 2
0% is occupied by a basic metal hydroxide having a valence of 2 or more. Examples are hydroxides of calcium, magnesium, barium, strontium, tin, zinc, aluminum and the like. Calcium hydroxide, magnesium hydroxide and barium hydroxide are preferred. If the amount is too small, pseudoplastic viscosity does not develop, and if too large, it does not dissolve in the aqueous medium.

Other bases which make up the remaining 80 to 95% of the neutralization equivalent include inorganic bases such as alkali metal hydroxides and aqueous ammonia, and methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine. , Isopropylamine, diisopropylamine, diethylenetriamine, triethylenetetramine, monoethanolamine, diethanolamine, 2-amino-2-methylpropanol, morpholine, N-methylmorpholine, N-ethylmorpholine, piperazine, dimethylethanolamine, diethylethanolamine, There are amines such as dimethyldodecylamine. Triethylamine, dimethylethanolamine and diethylethanolamine are preferred. Excessive base is not preferable because it accelerates the hydrolysis of the resin during storage.

The aqueous medium is usually ion-exchanged water, but it may optionally contain a small amount of a water-miscible organic medium. Examples thereof include diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monomethyl ether, methanol, ethanol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, t-butyl alcohol. , Dimethylformamide, N
-Methylpyrrolidone and the like.

The aqueous solution or dispersion of the resin can be combined with a blocked polyisocyanate compound or an aminoplast resin, which is typically a melamine resin, as a curing agent to prepare a thermosetting aqueous coating composition. These hardeners are well known in the paint art and will not require further explanation.

The invention is illustrated by the following examples. "%" In the examples is based on weight.

Production Example 1 155 parts by weight of coconut oil and 2 parts of trimethylolpropane were placed in a reaction vessel having a heating device, a stirrer, a nitrogen introducing pipe and a fractionating tower.
After charging 48 parts by weight and 1.7 parts by weight of dibutyltin oxide, heating was started under dry nitrogen to melt the raw material,
The temperature was gradually raised to 210 ° C., transesterification was performed, and the mixture was cooled. Next, 267 parts by weight of isophthalic acid and 59 parts of adipic acid
Parts by weight, neopentyl glycol 33 parts by weight, epol (hydrogenated polyisoprene diol, molecular weight = 1860,
Average repetition number n = 26, manufactured by Idemitsu Petrochemical Co., Ltd.) 41
By adding parts by weight, the temperature was gradually raised to 220 ° C. to carry out a dehydration esterification reaction. After dehydration esterification to a resin acid value of 10 and cooling to 150 ° C., adding 40 parts by weight of trimellitic anhydride, reacting to a resin acid value of 40, cooling to 140 ° C., and further adding 77 parts of ε-caprolactone. For 1 hour to complete the reaction. 75 parts by weight of Solvesso # 150 (aromatic hydrocarbon solvent, manufactured by Esso Chemical Co., Ltd.) and 75 parts by weight of butyl cellosolve were added to the obtained polyester resin to obtain a polyester resin varnish I having a resin solid content of 83%. The obtained polyester resin has a hydroxyl value of 137, an acid value of 37, a number average molecular weight of 2850 (in terms of polystyrene),
The water tolerance was 0.8.

Production Examples 2 to 4, 6 to 7 Polyester resins II to IV and VI and VII were obtained in the same manner as in Production Example 1 based on the formulations shown in Table 1. The properties of the obtained polyester resin are shown in Table 1.

[0025]

[Table 1]

1) Epol: hydrogenated polyisoprene diol, molecular weight = 1860, average number of repetitions n = 26, manufactured by Idemitsu Petrochemical Co., Ltd. 2) PIP: polyisoprene diol, molecular weight = 240
0, average number of repetitions n = 34, manufactured by Idemitsu Petrochemical Co., Ltd. 3) Polytail HA: hydrogenated polybutadiene diol,
Molecular weight = 2200, average number of repetitions n = 39, manufactured by Mitsubishi Kasei Co., Ltd. 4) R-45HT: polybutadiene diol, molecular weight =
2270, average number of repetitions n = 42, manufactured by Idemitsu Petrochemical Co., Ltd. 5) Solvesso # 150: aromatic hydrocarbon solvent, manufactured by Esso Chemical Co., Ltd. 6) Average molecular weight: polystyrene conversion by GPC 7) Nonvolatile matter: 150 ° C. Residue after heating for 1 hour at 8) Water Tolerance: 100 g of polyester varnish in a beaker (0.5 g) was dissolved in 10 ml of tetrahydrofuran (commercially available reagent), and ion-exchanged water was added dropwise to the product by using a burette. The water tolerance is defined as the amount (ml) of ion-exchanged water added dropwise when the mixed solution becomes cloudy.

Production Example 5 100 parts by weight of the polyester resin I obtained in Production Example 1, 5.5 parts by weight of Cymel 253 (a melamine resin manufactured by Mitsui Cytec Co., Ltd.) and 3.8 parts by weight of n-butanol were added.
Condensation was performed at 0 ° C. for 1 hour to obtain a polyester resin V having a resin solid content of 80%. The resulting polyester resin V had a hydroxyl value of 129, an acid value of 35, a number average molecular weight of 3310 (in terms of polystyrene), and a water tolerance of 0.85.

Example 1 a. Polyester Resin I 100 Obtained in Production Example 1
0.41 parts by weight of calcium hydroxide and 3.90 parts by weight of dimethylethanolamine were added to and mixed with 192.1 parts by weight of ion-exchanged water to obtain an aqueous polyester resin varnish A having a nonvolatile content of 28%. . The obtained aqueous polyester resin varnish A was treated with No. The 4-Ford cup was diluted with ion exchange until the viscosity reached 60 seconds, and the viscosity was measured with an E-type viscometer. As a result, the yield value was 18 dyne / cm ² .

B. The obtained aqueous polyester resin varnish A and melamine resin (Cymel 212, Mitsui Cytec Co., Ltd.) were mixed so that the solid content weight ratio was 70/30, and p-toluenesulfonic acid as a catalyst was added to the mixture.
5% by weight was added, and the mixture was applied onto a tin plate and baked at 140 ° C. for 30 minutes. The cured coating film obtained was strong and smooth.

Example 2 a. To 1100 parts by weight of the polyester resin obtained in Production Example 1, 0.41 parts by weight of calcium hydroxide and 4.42 parts by weight of triethylamine were added and mixed, and 191.6 parts by weight of ion-exchanged water was added to give a nonvolatile content of 28%. An aqueous polyester resin varnish B was obtained. The obtained aqueous polyester resin varnish B was treated with No. The Ford cup was diluted with ion-exchanged water until the viscosity reached 60 seconds, and the viscosity was measured with an E-type viscometer. The yield value was 18 dy.
It was ne / cm ² .

B. Obtained aqueous polyester resin varnish B and methyl ethyl ketone oxime blocked hexamethylene diisocyanate (nurate type, solid content 80%)
1 wt% of dibutyltin dilaurylate was added as a catalyst to a mixture of 70% and 30% by weight of solid content, and the mixture was coated on a tin plate and baked at 150 ° C. for 30 minutes. The cured coating film obtained was strong and smooth.

Examples 3-8 a. Polyester resins I to V obtained in Production Examples 1 to 5
In the same manner as in Example 1 based on Table 2, aqueous polyester resin varnishes C to H were obtained. The properties of the resulting aqueous polyester resin varnish are shown in Table 2.

B. A curability test was conducted on these obtained aqueous polyester resin varnishes C to H based on Table 3 in the same manner as in Example 1. The results are shown in Table 3.

Comparative Example 1 An aqueous polyester resin I was obtained in the same manner as in Example 1 except that the polyester resin I obtained in Production Example 1 was used according to Table 2.
The viscosity of the obtained aqueous polyester resin varnish I was measured in the same manner as in Example 1 and no yield value was obtained.

Comparative Examples 2 to 4 Water solubilization was carried out in the same manner as in Example 1 based on Table 2, but a stable aqueous dispersion was not obtained.

Comparative Example 5 a. An aqueous polyester resin varnish M was obtained in the same manner as in Example 1 based on Table 2. The viscosity of the obtained aqueous polyester resin varnish M was measured in the same manner as in Example 1, and the yield value was 19 dyne / cm ² .

B. A curability test was conducted on the obtained aqueous polyester resin varnish M in the same manner as in Example 1 based on the formulations shown in Table 3, but it did not show sufficient curability.

[0038]

[Table 2]

[0039]

[Table 3]

1) Ratio of basic compound to total amount of carboxyl groups of polyester resin. 2) Mol% of metal hydroxide in the basic compound. 3) Yield value: E-type viscometer, 0.5 rpm to 1
As a result of viscosity measurement up to 00 rpm, Casson plot was performed to obtain a yield value.

[0041]

[Table 4]

[0042]

[Table 5]

1) Cymel 212: Melamine resin manufactured by Mitsui Cytec Co., Ltd. 2) Blocked isocyanate: methyl ethyl ketone oxime-blocked hexamethylene diisocyanate (nurate type, solid content 80%) 3) Pencil hardness: JIS K-5400 compliant 4) Solvent resistance: coated with xylene-impregnated gauze The film surface was rubbed 10 times back and forth, and the state of the coating film at that time was observed.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshitaka Okude 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka Japan Paint Co., Ltd.

Claims (6)

[Claims] 1. All reaction components forming a polyester chain are
Based on the total amount thereof, (a) 10 to 60% by weight of an aromatic polycarboxylic acid, (b) a fatty acid having 6 or more carbon atoms or a fat or oil containing 0 to 0
30% by weight, (c) 1 to 30% by weight of a hydroxyl group-terminated polyalkadiene diol having an average degree of polymerization of 5 to 50, hydrogenated polyalkadiene diol alone or a mixture thereof, (d) the balance is (a), ( b), a reaction component other than (c), an acid value of 10 to 100, a hydroxyl value of 30 to 200, a water tolerance of 1 or less, and a weight average molecular weight of 10,000 to 20.
50,000 polyester resins containing 5-20% of the neutralization equivalents of a divalent or higher basic metal hydroxide and an amount of base that neutralizes at least 50% of the total carboxyl groups of the resin. An aqueous polyester resin varnish composition which is dissolved or dispersed in an aqueous medium. 2. The component (c) has a number average molecular weight of 1,00.
0 to 4,000 polyisoprene diol, polybutadiene diol or hydrogenated products thereof.
Composition. 3. The composition according to claim 1, which comprises, as the component (d), a cyclic lactone which accounts for 3 to 30% by weight of the total amount of all reaction components ring-opened and added to the polyester chain. 4. The composition according to claim 3, wherein the cyclic lactone is ε-caprolactone. 5. The composition according to claim 1, wherein the divalent or higher valent basic metal hydroxide is calcium hydroxide, magnesium hydroxide or barium hydroxide. 6. A thermosetting aqueous coating composition comprising the aqueous polyester resin varnish composition according to claim 1 and a blocked polyisocyanate compound or a melamine resin.