JPS5857475A - Water paint composition and production thereof - Google Patents

Abstract

PURPOSE:To provide a water paint compsn. having an excellent storage stability, etc., by dispersing fine powder of a carboxyl group-contg. resin in an aq. resin varnish obtd. by dispersing an aq. resin in an aq. medium by using a basic compd. CONSTITUTION:A basic compd. such as sodium hydroxide or ammonia is added to an aq. resin contg. carboxyl groups, such as a polyester or an acrylic synthetic resin. The mixture is dissolved or dispersed in an aq. medium to prepare an aq. resin varnish. Fine powder of a carboxyl group-contg. resin and, if necessary, a basic compd. are mixed with the above varnish. The mixture is heated at 35-95 deg.C with stirring to effect dispersion and to produce an aq. paint compsn. in which the neutralization ratio is 30-120% and the weight ratio (on a solid basis) of the carboxyl group-contg. resin to the aq. resin is 2:98-98:2. The resulting paint does not suffer deterioration such as thickening, gelling, etc. over a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-based coating composition and a method for making the same. More specifically, the present invention relates to the provision of a powder separation type water-based coating composition with excellent storage stability.

Powder-dispersed paints, which are made by dispersing powdered resin in a varnish in which the water-based resin is dissolved or dispersed in an aqueous medium, have a good balance between the flowability of the water-based resin varnish and the thick film properties of the powdered resin. This is a paint that overcomes the general drawback of water-based paints, such as poor sagging, and maintains the high level of pinhole property of powder resin, and has good workability. by the way,
Dispersion of powdered resin in an aqueous medium or aqueous resin varnish in the production of powder-dispersed paints has the disadvantage of requiring a very long time when using normal dispersion methods, and also It also has the disadvantage of poor stability. Especially when using a base-neutralized water-based resin varnish,
The resulting paint is sensitive to temperature changes (°
do.

The present inventors have conducted intensive research to solve the above-mentioned problems with the prior art, especially the stability of powder-dispersed water-based paints using base-neutralized water-based resin varnishes. If fine resin powder is used under specific dispersion operating conditions, a stable paint can be obtained in which the powder can be easily dispersed and the dispersion does not exhibit deterioration over time such as thickening or gelation even at considerably high temperatures. I found out that it is possible.

That is, the gist of the present invention is to provide a fine resin powder (I) having a carboxyl group, a basic compound ([), an aqueous resin (DI), and, if necessary, a compound that mutually reacts with the above (I) and/or (2). (TV), and the above (TI) is (I
) and (Iff) to the carboxyl group of 0,3 to
By containing it in an amount of 1.2 equivalents, the above (I) is dispersed in the aqueous medium and the above (III) is not dissolved.
' and dispersed, -1 solid content weight ratio of (I): (Iff) is 2:98 ~
There is an aqueous coating composition characterized by a ratio of 98:2, and a method for producing the same.

Carboxyl group-containing resin-powder used in the present invention (
Examples of the type of resin I) include polyester resin and acrylic resin. The particle size of these particles affects the stability of the paint over time, workability, and appearance of the paint film, so
The thickness may be 60μ, preferably 5 to 25μ. The acid value of the resin related to the amount of carboxyl groups is 15 to 300. Preferably it is 30 to 100. If the acid value is too low, the paint will not undergo the tertiary photocuring reaction, and if it is too high, free carboxyl groups will remain even if the resin is neutralized, and even if a coating film is formed, its water resistance will be affected. is inferior.

The basic compound (n) used in the present invention may be an inorganic or organic compound as long as it can neutralize the carboxyl group of the resin fine powder (I), such as lithium hydroxide, hydroxide Potassium, sodium hydroxide, ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, diethylenetriamine, triethylenetetramine, monoethanolamine, jetanolamine, triethanolamine, monoisopropylamine Paturamine, diisopropaturamine, dimethylethanolamine, diethylethanolamine, 2-amino-2-methylpropatur, 2-dimethylamino-2-methylpropatur, morpholine, n-methylmorpholine, n-ethylmorpholine , piperazine. Among these, organic basic compounds with a boiling point of 40 to 180°C are preferred. If the boiling point is too low, the compound will volatilize during the neutralization of the carboxyl groups of the fine resin powder (I), making it difficult to achieve the intended purpose. If the boiling point is too high, the compound will remain in the coating film and retard its curing, making it impossible to obtain good coating performance. Examples of such preferred compounds include diethylamine, triethylamine, dimethylethanolamine, diethylethanolamine, 2-amino-2-methylpropanol, morpholine, and n-methylmorpholine. In addition, it is also an amine compound having a hydroxyl group.
This is preferable because the fine resin powder (I) can be further easily dispersed.

This basic compound (TI) is the above-mentioned resin fine powder (■)
It may be used in an amount of 0.3 to 1.2 equivalents, preferably 0.5 to 1.0 equivalents, based on the total number of carboxyl groups in the aqueous resin (III) and the carboxyl groups in the water-based resin (III) described below. As a result, the above-mentioned (I) high dispersibility in an aqueous medium can be obtained, and a coating material with good stability can be obtained. In addition, if the amount of the compound (Ir) used is too small, the absolute amount of the compound (TI) to neutralize the carboxyl group of the above (I) will be insufficient, resulting in a decrease in the particle size of the above (I). If it is not too small, it will easily cause layer separation after dispersion, and on the other hand, if it is excessive, the above (
The particles of I) are solubilized in the aqueous medium, rendering the use of fine resin powder meaningless, and also causing the problem of significant foaming during coating film formation.

The aqueous resin (Iff) used in the present invention can be dissolved or dispersed in an aqueous medium by neutralizing the carboxyl group contained therein using a basic compound (If) as described above according to a conventional method. Any material that forms a stable aqueous resin varnish may be used, and examples thereof include alkyd, polyester, maleated polyalkadiene, epoxy, acrylic, and urethane.

Specifically, in the case of alkyd type and polyester type, a reaction between a polybasic acid and a polyhydric alcohol may be used.

In the case of maleated oils, carboxyl groups may be introduced by treating a drying oil (eg, linseed oil, castor oil, soybean oil, tung oil) with maleic anhydride to form an aqueous resin.

In the maleated polyalkadiene system, for example, polybutadiene (e.g., 1,2-polybutadiene, 1,4-polybutadiene, 1,2- and 1,4-copolymerized polybutadiene), polyisoprene, or polycyclopentadiene. For example, the double bond/QH (unsaturated carboxylic acid (e.g. maleic anhydride, hymic anhydride, fumaric acid, itaconic acid) is added to it, and a carboxyl group is introduced by Ruco and Ban, resulting in an aqueous resin. Good. For epoxy resins, various epoxy resins typified by the reaction of bisphenol A and epichlorohydrin (in addition, various compounds having other epoxy groups can be used. It can be used as it is, or it can be made water-soluble or water-dispersible by introducing an acidic group into part or all of the oxirane group.In the case of acrylics, α,β-unsaturated carboxylic acids (e.g. nialic acid) , methacrylic acid, cinnamic acid, crotonic acid, fumaric acid, citraconic acid, maleic anhydride) and acrylic acid esters (e.g. methyl esters, ethyl esters, flobyl esters, butyl esters, hexyl esters, lauryl esters) and/or methacrylates. Whether it is a base-neutralized water-based resin obtained by polymerizing acid esters (e.g. methyl ester, ethyl ester, floyl ester, butyl ester, hexyl ester, lauryl ester) or other polymerizable monomers as necessary. For urethane types, diisocyanate compounds (e.g. hexamethylene diisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, 4,4'-methylene bis(cyclohexyl isocyanate), inphorone diisocyanate) ) is a base-neutralized aqueous resin having a skeleton structure.

In the aqueous resins mentioned above, it is preferable to use a basic compound (OI) having a boiling point of 180° C. or less for neutralization of carboxyl groups.

In the paint of the present invention, the solid content weight ratio of the fine resin powder (■) to the aqueous resin (TIT) is 2298 to 98:
2, preferably in a ratio of 2298 to 60:40. If the amount of the former (I) is too small, the coating workability will be poor, while if it is too much, the flow properties of the coating film will be poor. Preferably, when the ratio of the latter (Tff) is 40 or more, the coating workability of the paint and the appearance and gloss of the coating film will be good.

The coating material of the present invention may contain a compound (1v) that reacts with the fine resin powder (T) and/or the aqueous resin (Iff), if necessary. Examples of darkening compounds (IV) include epoxy resins, melamine resins, polyvalent metal salts (e.g. cobalt naphthenate, lead naphthenate, zinc naphthenate), triglycidyl isocyanurate) (
TGIC) and dicyandiamide. The compounding amount of the compound may be such that the solid content weight ratio (I):(rV) is 100:0 to 20:80. By incorporating such a compound, the three-dimensional crosslinking reaction progresses and even higher coating film performance is achieved.

The present invention relates to an aqueous coating composition using water (preferably deionized water) as a medium and a method for preparing the same, but if necessary, a small amount of a solvent (e.g., ethylene glyfur monomethyl ether, ethylene glycol) may be used. Recol monoethyl ether, ethylene glycol monobutyl ether, methanol, ethanol, isopropyl alcohol, n-butyl alcohol, 5et-butyl alcohol, [-butyl alcohol, dimethylformamide) may be used.

In the present invention, in addition to the above-mentioned components I, various pigments and additives (eg, modifiers, dispersants, surface conditioners) can be used as necessary.

These may be blended into the fine resin powder (I), the aqueous resin (III), or both.

The coating composition of the present invention can be produced by the following two methods.

(a) That is, a varnish of aqueous resin (III) is produced according to a conventional method using excess or a part of the basic compound (TI), and this varnish is mixed with fine resin powder (I) and, if necessary, the remaining base. A chemical compound (TI) may be mixed therein, and the mixture may be heated, stirred, and dispersed.

(bl On the other hand, fine resin powder (1), basic compound (II)
and an aqueous resin (stone) may be mixed into an aqueous medium at the same time and dispersed by heating and stirring.

Therefore, it is desirable to carry out the heating and stirring dispersion at a temperature of 35 to 95°C, and the neutralization rate (
The total amount) is preferably 30 to 120%, preferably 50 to 100%. If the above temperature is too low, the above (I
) is not small enough to cause layer separation after dispersion, and on the other hand, if the particle size is too high, thermal energy This is a disadvantage. If the above neutralization rate is too low, the particle size of the above (I) will not become small, resulting in layer separation after dispersion, while if the above neutralization rate is too high, the above (I) will
Since it is solubilized in an aqueous medium, the use of fine resin powder becomes meaningless, and also causes the problem of significant foaming during coating film formation.

According to this manufacturing method, it becomes possible to differentiate the coating composition with high non-volatility, increasing the sagging film thickness limit, and reducing foaming of the formed coating film, increasing the pin film thickness limit, improving painting workability. will improve. The latter method (b) has an advantage over the former method (a) in that the paint manufacturing process is shortened.

In addition, when producing a pigmented paint composition,
In the method (a) above, a pigment paste is prepared using a part of the aqueous resin (III) varnish according to a conventional method, and on the other hand, the remaining aqueous resin (TII) varnish is used according to the heating stirring dispersion method described above. Prepare a dispersion of fine resin powder (I),
The above paste may be mixed with this dispersion liquid according to a conventional method, or may be dispersed by heating and stirring as described above.Also, the aqueous resin (
1) A pigment paste may be prepared using the entire amount of varnish, and fine resin powder may be mixed therein according to the heating stirring dispersion method described above.

In addition, in the method (b) above, a pigment paste is prepared using a part of the aqueous resin (■[), and on the other hand, the aqueous resin (II
I), the basic compound (If), and the fine resin powder (I) may be used to prepare a dispersion according to the above-mentioned heating stirring dispersion method, and the above paste may be mixed into this dispersion according to a conventional method. In addition, pigments are also present at the same time (I), (TI), (I
It may also be prepared by subjecting it to heating, stirring and dispersion I together with [[].

On the right, the compound (rV) is a fine resin powder (I
) may be melted and mixed in advance during production, and water-based resin (
III) may be mixed in when preparing the paint.

According to the present invention having the above configuration, a water-based paint composition having excellent storage stability can be obtained.

This coating composition may be applied in a conventional manner.

For example, if necessary, it may be diluted with water to obtain an appropriate viscosity, and a conventional coating method such as air spray, airless spray, electrostatic coating, roll coating, brush coating, or dip coating may be employed.

Next, the present invention will be specifically explained with reference to Reference Examples, Examples, and Comparative Examples. Note that parts refer to parts by weight.

Reference Example 1 30 g of deionized water and 90 V of rutile-type titanium oxide pigment were added to 467 of the water-based resin varnish (1) shown in Table 1.
After preliminary mixing, the mixture was mixed and dispersed in a glass beads medium using a paint conditioner for 40 minutes at room temperature to prepare a paste. This paste is well dispersed with a particle size of less than 1Oμ, and a viscosity (St-7-) of 100ku/25°C.
, and the nonvolatile content was 68W%.

Reference Example 2 Pigment dispersion pastes 2) to (4) were obtained in the same manner as in Reference Example 1 using each aqueous resin varnish shown in Table 1 and having the formulation shown in Table 2.

Table 1: DMEA Nidimethylethanolamine (boiling point 135°C) TEA: (Liethylamine (boiling point 90°C)) Example 1 4652 of water-based resin varnish (1) in Table 1 was dissolved in 30 g of deionized water. Gradually add 342 of resin fine powder (1) in Table 3 while heating and stirring, and after addition, add 15% at a temperature of 70°C.
The mixture was held for a minute and then stirred and dispersed. As a result, a highly stable dispersion liquid was obtained, and the neutralization rate (total vertical) of this liquid was 47%.

Add 16 of the pigment dispersion paste 1) of the above reference example to the above dispersion.
67 was added and stirred thoroughly, and further HMMM (crystalline hexamethoxymethylolmelamine) 209- was added and mixed to obtain a coating composition. This product had a non-volatile content of 64 W[%, a viscosity (St-7-) of 110 ku/25°C, and a solid content ratio of (fine resin powder)/(aqueous resin varnish) of 34/66.

Examples 2 to 11 and Comparative Examples 1 to 3 Various coating compositions shown in Table 4 were obtained in the same manner as in Example 1.

Table 3 Example 12 The coating compositions obtained in Examples 1 to 1O and Comparative Examples 1 to 3 were stored at 40° C. for 10 days to test their stability. The results are shown in Table 5. Furthermore, when the coating workability of the above coating composition on a matte steel plate was evaluated, the results shown in Table 5 were obtained.

In addition, the paint stability in the table is based on the patent applicant in Table 5, Nippon Paint Co., Ltd.'s representative patent attorney, Aoyama Aoyama, and one other person. City official letter (spontaneous) October 8, 1980, Commissioner of the Japan Patent Office1, Table of the case, Patent Application No. 156886, filed in 1982,2, Name of the invention: Water-based paint composition and its manufacturing method Representative: Masao Suzuki Name: Patent attorney (6214) Blue Mountain Roar (Baka 1)
name) 5. Date of amendment order: voluntary (submitted at the same time as the request for examination of the application) 6. Column 7 for detailed explanation of the invention in the specification subject to amendment 7. Contents of amendment .

(1) Page 5, lines 5-6 [Even if the resin is neutralized] was deleted.

(2) On page 6, line 10, insert ``Therefore, it is necessary to raise the curing temperature.'' after ``...cannot be obtained.''

(3) On page 14, line 2, "Fine resin powder..." was corrected to "If it is solid at room temperature, it is a fine resin powder..."

(4) Page 14, lines 3-4.

"For water-based resin (III)" has been corrected to "If it is liquid at room temperature."

(5) In Table 1 on page 15, in the neutralizing base column for water-based resin varnish (1), rTEAJ was corrected to rDMEAJ.

(6) End of page 16 Removed the word "crystalline".

(7) In Table 4 on page 18, "-[Varnish J" under "Coating compositions" has been corrected to read "Aqueous resin varnish."

that's all

Claims (1)

[Scope of Claims] (1) A fine resin powder having a carboxyl group (I), a basic compound (n), an aqueous resin (II) and, if necessary, mutually reacting with the above (1) and/or (III); 2 Compound (IV), and the above (II) is combined with (I) and (
Ilr) (7: 0.3 to total amount of carboxyl groups
It is contained in an amount of 1.2 equivalents. An aqueous coating composition characterized in that the weight ratio of 2 is 98 to 98:2. 2. The solid content ratio of (I) to (III) is 2:
3. The composition of item 1 above, wherein (IV) is an epoxy resin and/or a melamine resin. 4. The composition according to item 1 above, wherein the ruts in (n) are in a proportion of 0.5 to 1.0 equivalents based on the total amount of carboxyl groups in (I) and (Iff). 5. The solid content ratio of (1) and (IV) above is 100:
The composition of item 1 above, wherein the ratio is 0 to 20:80. 6. A varnish is obtained by dissolving or dispersing the aqueous resin (m) in an aqueous medium using all or part of the basic compound (II), and a fine resin powder (I) having a carphoxyl group is added to the varnish. ) and, if necessary, the remaining amount of the basic compound (Il,), and the temperature is 35 to 95°C.
Disperse with heating and stirring to achieve a neutralization rate of 30-120% and 7.
(I) : (N) solid content weight ratio 2:98-98
: System 2)) A method for producing an aqueous paint composition. 7. Fine resin powder (I) having a carboxyl group 1,
A basic compound (IT) and an aqueous resin (Iff) are mixed into an aqueous medium, and the mixture is heated and stirred at a temperature of 35 to 95°C to disperse it, so that the above (D) is dispersed in the aqueous medium and (I[) is dissolved or dispersed. and neutralization rate of 30-120% and (I
): (1ff) A method for producing an aqueous coating composition characterized by obtaining a system with a solid content ratio of 2:98 to 98:2.