JPS5825384B2 - Water-dispersed thermosetting coating composition - Google Patents

Description

[Detailed description of the invention] - The present invention relates to a water-dispersed thermosetting coating composition.

More specifically, the present invention relates to a water-dispersed thermosetting coating composition that has excellent storage stability and forms a coating film that has excellent temporary rust prevention, corrosion resistance, cold/heat cycle resistance, chemical resistance, and weather resistance.

BACKGROUND ART In recent years, efforts have been made to make paints and coatings pollution-free and resource-saving, and powder coatings and water-based coatings are increasingly being used as coatings suitable for this purpose.

However, such powder coatings require special coating equipment, are not as easy to apply as conventional solvent-based coatings, and have excellent coating film smoothness and a difficult-to-image finished appearance.
There were problems in use, such as difficulty in coating thin films with a thickness of 0μ or less.

Furthermore, among water-based paints, water-soluble paints have a low solid content concentration during painting, so it is difficult to apply a thick film at once. The problem was that a high degree of durability could not be obtained.

On the other hand, emulsion paints have had the problem of poor water resistance, chemical resistance, etc. of the paint film because they use a large amount of surfactant.

As a method to solve these problems, a slurry paint (water-dispersed paint) has been proposed in which resin powder is suspended in water and applied like a water-based paint.

In general, acrylic resins, polyester resins, epoxy resins, alkyd resins, etc. are known as resins used in such slurry paints, but they are especially important for stability during storage, smoothness of the coating film, and finish. Acrylic resin and polyester resin are said to be preferable from the viewpoint of appearance.

In addition, epoxy resin or the like may be used in combination to further enhance anti-corrosion properties.

However, if an epoxy resin is used in combination, the weather resistance will be impaired, so it is not preferable to use it as a component of the top coat resin.

By the way, when melamine resin is used as a cross-linking agent, it has a drawback in terms of painting workability because it sometimes causes foaming (flanks) when it is painted in a thick film. I needed to.

Additionally, since slurry paints generally use water,
When painted directly onto iron plates such as mild steel plates, similar to conventional water-based paints, there is a problem in that phenomena such as temporary rusting that cannot be seen with solvent-based paints occur.

However, in order to suppress this phenomenon, temporary rust preventive agents and the like are often used in the same way as water-based paints, but the use of these agents is not preferable because it has an adverse effect on storage stability.

The present invention aims to solve these problems.

In other words, it has excellent storage stability, is easy to use during work, and does not have any defects such as cracking or cracking, and has excellent gloss, smoothness, temporary rust prevention, corrosion resistance, cold/heat cycle resistance, chemical resistance, weather resistance, etc. An object of the present invention is to provide a water-dispersible thermosetting coating composition with excellent coating performance.

That is, the present invention comprises (A) (j) unsaturated polyester resin...
...2-30 weight coefficient weight<rr)<a) N-alcoxine methylated monomer of α, β-monoethylenically unsaturated carboxylic acid amide, (b) phosphate group-containing α, β-monoethylene Sexually unsaturated monomers and (
) → Monomer mixture consisting of α,β-monoethylenically unsaturated monomers other than the above (a) and (b)……98
Fine powder thermosetting resin particles consisting of a polyester-modified vinyl resin having a hydroxyl value of 10 to 120 obtained by weight raft polymerization with a weight ratio of 0 to 70, and (B) a blocked isocyanate compound. The polyester-modified vinyl resin used in the present invention is unsaturated. It is obtained by graft polymerizing a polyester resin (A(i)) with a mixture of α,β-monoethylenically unsaturated monomers (CA)(i+)), and the flexibility of the polyester resin It is characterized by providing vinyl resin with excellent properties such as properties, pigment dispersibility, and coating film appearance.

Therefore, it is necessary to use α,β-unsaturated dicarboxylic acid as a raw material for the unsaturated polyester resin used in the present invention, and this component is present in the unsaturated polyester resin.
It is preferable to carry out the reaction in a proportion of 10% by weight, preferably 3 to 7% by weight.

In the above range, if the amount of this component is less than the weight limit, the amount will not be sufficient for the α,β-monoethylenically unsaturated monomer when producing the polyester-modified vinyl resin, and therefore the polyester modification will not be completed. The resulting product is an unsaturated polyester resin and α.

The composition is blended with a polymer of β-monoethylenically unsaturated monomer, and the coating film may become white.

Further, due to the difference in reactivity between the crosslinkable reactive group and the blocked isocyanate compound, coating film performance, particularly adhesion, tends to deteriorate, which is not preferable.

On the other hand, if the content of this component is 10% by weight or more, gelation occurs during the reaction with the α,β-monoethylenically unsaturated monomer, which is not preferable.

Specific examples of the α,β-unsaturated dicarboxylic acid component include:
Examples include fumaric acid, maleic acid (anhydride), itaconic acid, glucuronic acid, citraconic acid (anhydride), and one kind or a mixture of two or more of these may be used.

In the synthesis of the unsaturated polyester resin used in the present invention, the carboxylic acid component other than the above acid is preferably 29 to
Let it react with a weight of 69 weight.

Specific examples of the components include phthalic anhydride, isophthalic acid, trimellitic acid (anhydride), pyromellitic acid (anhydride), tetrahydrophthalic acid (anhydride), hexahydrophthalic acid (anhydride), and methyltetrahydro (anhydrous). phthalic acid,
Examples include methylhexahydrophthalic anhydride, hymic anhydride, succinic acid (anhydride), adipic acid, sebacic acid, benzoic acid, para-tert-butylbenzoic acid, etc., and these can be used singly or as a mixture of two or more. 3
In the synthesis of the unsaturated polyester resin used in the present invention, the polyhydric alcohol component is preferably reacted in an amount of 30 to 70% by weight.

Specific examples of the components include ethylene glycol, diethylene glycol, phlopylene gellicol, neopentyl glycol, dipropylene glycol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, butanediol, bentanediol, hexane. Diol, 1,4-
Examples include cyclohexane dimetatool, (hydrogenated) bisphenol A, and the like.

These may be used alone or in combination with a mixture of two or more thereof, and if necessary, a glycidyl ester of tertiary synthetic saturated fatty acid (manufactured by Cardulor E Nigel Chemical Co., Ltd., trade name).

In addition, animal and vegetable oils, their fatty acids, petroleum resins, rosin, phenol resins, epoxy resins, etc. can also be used as modified raw materials for unsaturated polyester resins, if necessary.

The unsaturated polyester resin in the present invention is produced by a single-stage reaction or a multi-stage reaction by a known method, and the reaction method is not limited.

Further, a polymerization solvent described below can be used as a diluent if necessary.

The acid value of the unsaturated polyester resin of the present invention is 50 or less (
Resin solid content: 2 or less (all indications of acid value in the present invention are the same), hydroxyl value 50 to 250 (resin solid content: hereinafter all indications of hydroxyl value in the present invention are the same), molecular weight is weight average molecular weight 2 ,000 to 120,000 is preferred.

The weight average molecular weight is a value measured by gel permeation chromatography (Model A301, manufactured by Toyo Soda Co., Ltd.).

(Hereinafter, the weight average molecular weight in the present invention was measured in the same manner.

) In the present invention, if the acid value of the unsaturated polyester resin is 50 or more, the alkali resistance etc. in the final coating performance after graft polymerization of the α,β-monoethylenically unsaturated monomer mixture will decrease. do.

In addition, if the hydroxyl value is lower than 50, the crosslinkability between the polyester-modified vinyl resin obtained by graft polymerization of the α,β-monoethylenically uncelled monomer mixture and the block isocyanate compound described below tends to be insufficient, and If it is higher than 250, it is not preferable because the water resistance of the resulting coating film tends to decrease due to an increase in the number of polar groups.

In addition, if the weight average molecular weight is lower than 2,000, the properties of the polyester resin cannot be fully exhibited;
If it exceeds 0,000, the molecular weight of the polyester resin is too high, and when modified with a mixture of α,β-monoethylenically unbonded monomers, the viscosity becomes too high, which impairs workability, which is not preferable. .

In the present invention, the polyester-modified vinyl resin has at least α added to the unsaturated polyester resin.

Contains an N-alkoxymethylated monomer of β-monoethylenically unsaturated carboxylic acid amide and a phosphate group-containing α,β-monoethylenically unsaturated monomer, and contains other monomers, such as those described below. Usual α, β-monoethylenically unsaturated carboxylic acids, hydroxyalkyl esters of said carboxylic acids, alkyl esters of acrylic acid or methacrylic acid, etc.
A monomer mixture with β-monoethylenically unsaturated monomer,
It is obtained by graft polymerization.

The polyester-modified vinyl resin in the present invention must contain a hydroxyl group in the molecule in order to undergo a self-crosslinking reaction, including a crosslinking reaction with a block isocyanate compound.

Therefore, when the hydroxyl value of the unsaturated polyester resin is low, α
, hydroxyalkyl esters of β-monoethylenically unsaturated carboxylic acids are preferably used.

The hydroxyalkyl ester monomer is preferably an α,β-monoethylenically unsaturated monomer mixture [component (A) (ii) above] so that the hydroxyl value of the polyester-modified vinyl resin is 10 to 120. It is used within the range of 1 to 15 weight units, particularly preferably 3 to 12 weight units.

If the monomer is used in an amount exceeding 155% by weight within the above range, the polyester-modified vinyl resin will have a high viscosity, and the crosslinking density after the thermosetting reaction with the blocked isocyanate compound will become too high, making it difficult to coat. This is not preferable because it tends to reduce the flexibility, water resistance, etc. of the membrane.

Specific examples of the monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 3-hydroxypropyl (meth)acrylate.
-Hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (
meth)acrylate, neopentyl glycol mono(meth)acrylate, 3-butoxy-2-hydroxypropyl(meth)acrylate, 2-hydroxy-1-phenylethyl(meth)acrylate, polypropylene glycol mono(meth)acrylate, glycerin mono(meth)acrylate There are meth)acrylates, etc., and these may be used alone or as a mixture of two or more.

In addition, in the present invention, the N-alkoxymethylated monomer component of the α,β-monoethylenically unsaturated carboxylic acid amide used for graft polymerization with the unsaturated polyester resin is α,β-monoethylenic. Necessary for crosslinking reaction of unsaturated carboxylic acid with hydroxyalkyl ester component and polyester resin component.

It is preferable to carry out the graft polymerization reaction of this component in the α,β-monoethylenically unsaturated monomer mixture in an amount of 3 to 15 weight units, preferably 5 to 10 weight units.

When the content of this component is 3% by weight or less, the crosslinking reaction of the polyester-modified vinyl resin becomes insufficient, and the solvent resistance of the coating film decreases.

Moreover, if it exceeds 155% by weight, gelation occurs during the graft polymerization reaction, which is not preferable.

Specific examples of this component include N-methoxymethyl (meth)
Acrylamide, N-ethoxymethyl (meth)acrylamide, N-n-propoxymethyl (meth)acrylamide, N-impropoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide,
N-5ec-butoxymethyl (meth)acrylamide,
N-1-butoxymethyl(meth)acrylamide, N-
α, β such as isobutoxymethyl (meth)acrylamide
- N-alkoxymethylated products of monoethylenically unsaturated carboxylic acid amides; or N-methylolated products thereof, and the like, and these may be used alone or as a mixture of two or more kinds.

Furthermore, in the present invention, as a kind of α,β-monoethylenically unsaturated monomer mixture constituting the polyester-modified vinyl resin of the present invention, a phosphate group-containing α,β-monoethylenically unsaturated monomer is used. Use the body as an essential ingredient.

Phosphate group-containing α,β- in polyester modified vinyl resin
By introducing the monoethylenically unsaturated monomer, even when the coating composition of the present invention is applied directly onto an iron plate, it not only suppresses temporary rusting, but also improves the storage stability of the composition. It is possible to obtain a coating film that has even stronger adhesion to the metal surface and has significantly superior corrosion resistance and water resistance.

The phosphate group-containing α,β-monoethylenically unsaturated monomer is used in an amount of 0.01 to 1.0% by weight, preferably 0.03 to 0.7% by weight, in the monomer mixture. .

If the monomer is used in an amount less than 0.011% by weight, the temporary rust prevention effect, storage stability, and high corrosion resistance, which are the characteristics of the present invention, cannot be sufficiently exhibited; If it is used as a polymer, it is not preferable because it tends to gel during the polymerization reaction process.

In addition, sufficient effects can be obtained with 1.0% by weight or less, so
It is economically undesirable to use more than 1.0% by weight.

Specific examples of the monomer include acidophosphoxyethyl (meth)acrylate, acidophosphoxypropyl (
Primary phosphoric acid esters of acrylic acid or methacrylic acid containing a hydroxyl group such as meth)acrylate, 3-chloro-2-acidophosphoxypropyl methacrylate; bis(meth)acryloxyethyl phosphate;
It is one kind or a mixture of two or more kinds of acrylic alcohol acid phosphate, vinyl phosphate, mono[2-hydroxyethyl (meth)acrylate coacid phosphite, etc., and their salts and esters.

Such a monomer is prepared by reacting an α,β-monoethylenically unsaturated monomer having a hydroxyl group with phosphoric anhydride,
It is produced by hydrolyzing the product, but its geothermal phosphoric acid, metaphosphoric acid, phosphorus oxychloride, phosphorus trichloride,
It can also be produced using phosphorus pentachloride.

In the present invention, the hydroxyalkyl ester monomer of the α,β-monoethylenically unsaturated carboxylic acid, α,
Monomers other than the N-alkoxymethylated monomer of β-monoethylenically unsaturated carboxylic acid amide and the phosphate group-containing α,β-monoethylenically unsaturated monomer may be used in combination.

Such monomers are preferably used in an amount of 80% by weight or more in the monomer mixture.

Specific examples of the monomer include α,β-monoethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid: methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (
meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, 5ec-butyl(meth)acrylate, t-butyl(meth)acrylate, isobutyl(meth)acrylate, n-hexyl(
Alkyl ester acids of acrylic acid or methacrylic acid such as meth)acrylate, 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, lauryl(meth)acrylate, tridecyl(meth)acrylate, and stearyl(meth)acrylate; Others N,
N'-dimethylaminoethyl (meth)acrylate,
Dialkyl esters of fumaric acid such as glycidyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl methacrylate, benzyl methacrylate, di-butyl fumarate, styrene, vinyltoluene, α
- Monomers such as methylstyrene, (meth)acrylonitrile, and vinyl acetate can be mentioned.

Such monomers can be used singly or in an appropriate combination of two or more, depending on the purpose and use of the coating composition.

The polyester modified vinyl resin contains 2 to 30 weight percent of the unsaturated polyester resin and 70 to 70 weight percent of the monomer mixture.
It consists of a graft polymerization reaction product with a weight ratio of 98%.

The amount of modification of the unsaturated polyester resin is from 2 to 30 parts by weight, preferably from 3 to 20 parts by weight.

If the weight ratio is lower than 2, the excellent flexibility, pigment dispersibility, and coating film appearance of polyester resin cannot be fully demonstrated, and if the weight ratio is higher than 30, the hardness, which is a characteristic of vinyl resin, will not be fully demonstrated. The stain resistance etc. will be impaired.

The polyester-modified vinyl resin of the present invention is produced by conventional solution polymerization.

For example, a method in which the remaining monomer mixture and a polymerization initiator are dropped into a mixture of an unsaturated polyester resin, a part of the monomer mixture, and a polymerization solvent, and then polymerized, or a method in which the remaining monomer mixture and a polymerization initiator are polymerized,
There are methods of polymerizing by dropping an unsaturated polyester resin, a monomer mixture, and a polymerization initiator, and there are no particular restrictions on the solution polymerization method, but the polymerization conditions are set so that the nonvolatile content is 50% by weight or less. It is preferable to carry out the polymerization.

That is, if the polymerization is carried out at a weight ratio of 50 or more, the viscosity becomes high and gelation occurs, which is not preferable.

Generally, the polymerization temperature range is about 50 to 150°G, and the polymerization reaction time is about 4 to 12 hours, depending on the temperature.

Further, as the polymerization solvent used in the solution polymerization method, a water-soluble or water-miscible solvent is used.

For example, alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, propyl alcohol, ethylene glycol monomethyl ether,
Ethylene glycol derivatives such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate; diethylene glycol derivatives such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether; methyl acetate, ethyl acetate, butyl acetate, etc. Ketones such as methyl ethyl ketone and methyl isobutyl ketone are used.

These polymerization solvents may be used alone or in an appropriate combination of two or more.

In particular, it is preferable that the solubility in water is about 10 to 30% by weight at 20°C.

In addition, examples of the polymerization initiator used include benzoyl peroxide, t-butyl perbenzoate, t-
Examples include organic peroxides such as butyl hydroperoxide, rimene hydroperoxide, di-t-butyl peroxide, and t-butyl peroctoate, and ab compounds such as azobisisobutyronitrile and azodiisobutyronitrile. .

One or more of these polymerization initiators may be used in combination as appropriate.

The polymerization initiator is used in an amount of about 0.1 to 15% by weight of the non-volatile content during the production of the polyester-modified vinyl resin.

If necessary, chain transfer agents such as dodecyl mercaptan, 2-ethylhexyl thioglycolate, carbon tetrachloride, etc. may be used to adjust the molecular weight.

The chain transfer agent is preferably used in an amount of about 0 to 5 weight percent based on the nonvolatile content during production of the polyester-modified vinyl resin.

The hydroxyl value of the polyester-modified vinyl resin of the present invention is 1
The acid value is in the range of 0 to 1201, preferably 20 to 8o, and the acid value is preferably in the range of 3 to 40, preferably 5 to 25.

When the acid value is less than 3, thermosetting properties are insufficient, resulting in poor coating film hardness, water resistance, corrosion resistance, durability, etc. On the other hand, when the acid value is greater than 40, coating film performance and storage stability are also reduced. .

Moreover, when the hydroxyl value is 10 or less, the crosslinking density decreases and the solvent resistance decreases.

On the other hand, if it is larger than 120, the flexibility and water resistance will decrease.

The weight average molecular weight of the polyester modified vinyl resin of the present invention is 20,000 to 200,000, preferably 30.00.
It is preferably within the range of 0 to 150,000.

In the above range, if the weight average molecular weight is less than 20,000, the coating performance will be insufficient, while if the weight average molecular weight is more than 200,000, the smoothness of the coating will be impaired.
Undesirable.

Since the polyester-modified vinyl resin of the present invention is highly reactive, it tends to increase in viscosity at high temperatures such as in summer.

In such cases, in order to further improve storage stability, the acid groups introduced into the polyester-modified vinyl resin can be neutralized with a basic compound to make the polyester-modified vinyl resin even more stable. .

Examples of the basic compound include inorganic alkalis such as sulfur hydroxide and potassium hydroxide; ammonia, momethylamine, dimethylamine, trimethylamine, triethylamine, monoethylamine, mono-n-propylamine, dimethyl-n-propylamine. Water-soluble amines such as monoethanolamine, jetanolamine, triethanolamine, N-methylethanolamine, N-
Examples include one or a mixture of two or more water-soluble oxyamines such as aminoethylethanolamine, N-methylgetanolamine, monoisopropanolamine, diisopropanolamine, tripropropanolamine, and hydroxylamine.

When neutralizing with such a compound, it includes neutralizing some or all of the acid groups in the polyester-modified vinyl resin, and furthermore, the stability of the polyester-modified vinyl resin composition is Alternatively, it can be added in an excessive amount in consideration of coating film performance and the like.

Next, the blocked isocyanate compound (B) used in the present invention is a blocked isocyanate compound having two or more incyanate groups in one molecule, and all of the isocyanate groups are masked with a blocking agent. It is a compound.

The blocked isocyanate compound is necessary for the crosslinking reaction with the polyester-modified vinyl resin, and is characterized by providing the excellent weather resistance and chemical resistance that urethane resins have.

The blocked isocyanate compound is a polyisocyanate compound having two or more incyanate groups in one molecule, such as ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocyanate, m-phenylene diisocyanate, p- Phenylene diisocyanate, 2.4-tolylene diisocyanate, 2.6-tolylene diisocyanate, ■
, 5-naflethylene diisocyanate, 4.4', 4
″-triphenylmethane triisocyanate, 4.4′
-diphenylmethane-diisocyanate, 3,3'-dimethyl-4,4'-diphenylene-diisocyanate,
m-xylylene diisocyanate, p-xylylene-
Excess of polyisocyanates such as diisocyanate, isophorone diisocyanate, lysine isocyanate and said isocyanate compounds, such as ethylene glycol, propylene glycol, 1,3-phthylene gelicol, neopentyl glycol, 2,2,4-trimethyl 1
, 3-bentanediol, hexamethylene glycol,
Difunctional or higher functional polyisocyanates obtained by addition reaction with low-molecular polyols such as cyclohexane dimetatool, trimethylolpropane, hexanetriol, glycerin, and pentaerythritol, polyisocyanates with biuret structures, polyisocyanates with allophanate bonds, etc. This is an isocyanate compound blocked with a blocking agent.

The blocking agents include phenols such as phenol and cresol, alcohols such as methanol, benzyl alcohol, and ethylene glycol monoethyl ether, active methylenes such as methyl acetoacetate and dimethyl malonate, and acid amides such as acetanilide and acetamide. Other imide-based, amine-based, imidazole-based, urea-based, carbamate-based, imine-based, oxime-based, mercapkun-based,
There are sulfite-based, lactam-based, etc.

The crosslinking reaction in the composition of the present invention is carried out by the hydroxyl group in the polyester-modified vinyl resin, the N-alkoxymethyl group in the polyester-modified vinyl resin, and the isocyanate group of the blocked isocyanate compound.

The usage ratio of polyester modified vinyl resin and block isocyanate compound is (hydroxyl group in polyester modified vinyl resin)/(isocyanate group in block isocyanate compound) -110.1 to 1/1.2 (equivalent ratio)
The range is such that

The equivalent ratio is approximately the following weight ratio.

That is, the solid content weight ratio of the polyester modified vinyl resin and the blocked isocyanate compound is approximately 40,760 to
The ratio is 99.570.5.

However, in the present invention, the N-alkoxymethyl group in the polyester-modified vinyl resin performs a self-crosslinking reaction, but also reacts with a hydroxyl group. Isocyanate group in the compound) -170,2~
It is preferable to use it within a range of 110.8 (equivalent ratio).

If the amount of the blocked isocyanate compound used is significantly small, the effects of improving the chemical resistance, weather resistance, etc. of the coating film, which are the characteristics of the present invention, will be poor.

On the other hand, if it becomes significantly larger, coating film performance such as water resistance will deteriorate due to unreacted incyanate groups.

The softening temperature of the mixed resin particles of polyester-modified vinyl resin and blocked isocyanate compound used in the present invention is preferably 30 to 100°C.

More preferably, the softening temperature is between 40 and 80°C.
If it is lower than 100°C, the storage stability of the paint tends to decrease, and if it is higher than 100°C, the smoothness of the coating film will be insufficient, which is not preferable.

In addition, in the present invention, known acid catalysts and dissociation catalysts for promoting the crosslinking reaction between the polyester-modified vinyl resin and the blocked isocyanate compound, as well as epoxy resins, cellulose resins, amino resins, polyester resins, etc., may be used as necessary. It is also possible to use one or more types of coating film-forming resins in combination.

Next, the method for producing the water-dispersed thermosetting coating composition of the present invention will be explained.

As the manufacturing method, the usual mechanical pulverization method used in the manufacturing of conventional powder paints and slurry paints can also be applied.

However, when the softening point is low, the adhesiveness of the resin particles is too high and it becomes difficult to powderize them.

The water-dispersed thermosetting coating composition of the present invention can be advantageously produced, for example, by a special method as described below.

First, a mixed resin composition of a predetermined amount of the polyester-modified vinyl resin and, if necessary, a basic compound and a blocked isocyanate compound that neutralize some or all of the dispersing groups in the polyester-modified vinyl resin; (as appropriate, the curing catalyst, dissociation catalyst, other coating film-forming resin, etc. are dissolved in the water-soluble solvent or water-miscible solvent) to form a resin solution,
Further, if necessary, a pigment is added and kneaded and dispersed to obtain a pigment dispersion.

The solvent used in this case is the same as the polymerization solvent used in the solution polymerization method.

The amount used is such that the nonvolatile content of the resin solution or pigment dispersion is in the range of 30 to 80% by weight.

Then, this resin solution or pigment dispersion is emulsified into fine particles in water in an amount that dissolves all of the hexagonal solvent or water-miscible solvent contained therein.

The amount of water used at this time is at least 6 times the amount (weight) of the resin solution or pigment dispersion, taking into account the filtration process after emulsification. An IK of about 4 or less is preferred.

The resin solution or pigment dispersion can be emulsified by dropping, pouring, or spraying the solution or dispersion into water under vigorous stirring, or by mixing water and the solution or dispersion using a line mixer. However, at this time, the temperature of the mixed liquid increases due to stirring, and in order to prevent the resin particles from coalescing or becoming integrated due to the softening of the resin, the mixed liquid is cooled to a temperature of 30°C. It is preferable to keep it below.

The stirring or mixing using a line mixer is carried out until the solvent in the emulsion particles is transferred to water and resin particles are formed.

In this way, the solvent in the emulsion fine particles is extracted into water, and resin particles are obtained.

The resin particles are separated from the water-solvent mixture by filtration or centrifugation, and if necessary, water washing and separation are repeated a necessary number of times to obtain resin particles in the form of a slurry or a water-containing cake.

In this way, preferably an average particle size of about 1 to 200
Resin particles between μ are obtained.

Furthermore, after adding a surfactant and/or thickener and water to this slurry-like or water-containing cake-like resin particles,
The resin particles are finely pulverized using a dispersing machine normally used for manufacturing paints, such as a sand mill, a ball mill, a disperser, a Sassmeyer mill, and a Sentry mill, so that the average particle diameter is approximately 1 to 1.
Adjust between 50μ.

The thus obtained resin particles of the present invention contain a polyester-modified vinyl resin and a blocked isocyanate compound in one particle.

That is, each particle necessarily contains groups that react with each other when heated, that is, a hydroxyl group, an N-alkoxymethyl group, and an isocyanate group.

Therefore, when the composition of the present invention is heated, a coating film having excellent performance can be obtained through crosslinking in the resin particles and crosslinking reaction between the resin particles.

The water-dispersed thermosetting coating composition of the present invention preferably contains the resin particles dispersed in the form of fine particles having an average particle diameter of 1 to 50 μm.

If the average particle diameter is smaller than 1 μm, the cohesiveness of the particles increases, and properties similar to those of water-soluble paints, such as easy foaming during film formation by heating, are undesirable.

On the other hand, if it is larger than 50μ, the resin particles tend to precipitate and aggregate during storage, making it impossible to obtain a smooth coating surface, which is not preferable.

In particular, resin particles having an average particle diameter of 5 to 30 μm are suitable for the present invention because they provide excellent storage stability and provide a smooth coating film without foaming.

The composition of the present invention may also contain, if necessary, a curing catalyst, a dissociation catalyst, organic and inorganic coloring and extender pigments commonly used in paints, a temporary rust preventive agent, a flow aid, an antifoaming agent, an anti-settling agent, Additives such as fungicides and preservatives, other water-soluble resins, and film-forming resins such as hydrosils and emulsion resins can be included.

As mentioned above, since the softening temperature of the resin particles is preferably 30 to 100°C, components such as pigments that do not melt at the heating film forming temperature of the paint should be added to the resin particles in an amount of 50% by weight or less. is preferred.

As the surfactant used in the present invention, known surfactants such as nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants can be used. For example, sorbicun fatty acid ester, polyoxyethylene sorbicun fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alcohol ether, chrycerin fatty acid ester, propylene glycol fatty acid ester, polyoxyethylene castor oil derivative, polyoxy Ethylene alkyl phenyl ether, alkyl phosphate ester, polyoxyethylene phosphate ester; anionic surfactants include alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, alkyl sulfosuccinate, N
-Acyl sarcosine salt; As the cationic surfactant, quaternary ammonium salts, pyridinium salts, etc. can be used.

From the viewpoint of dispersion stability of resin particles and coating film performance, nonionic surfactants are preferred, and those having an HLB of 8 to 18 are particularly preferred.

Further, as the above-mentioned thickener used in place of or in combination with these surfactants, those conventionally used in water-based resin paints can be used.

These include, for example, cellulose water-soluble resins such as methyl cellulose, ethyl cellulose, and hydroxyethyl cellulose; polyvinyl alcohol; polyethylene water-soluble resins such as polyethylene glycol ether and polyethylene oxide; methyl vinyl ether maleic anhydride copolymer, and ethylene maleic anhydride. Copolymers, maleic anhydride copolymers such as styrene maleic anhydride copolymers, water-soluble resins, ammonium, amine salts and sodium salts of nialic acid polymers, bentonite, polyvinylpyrrolidone, alginates, polyacrylamide and parts thereof Examples include hydrolysates, naturally occurring water-soluble products such as casein and gelatin, and resins.

The above-mentioned surfactant and/or thickener is added in an amount of 0.01 to 5.0 parts by weight based on the fine powder resin particles.

If the amount added is less than 0.011 parts by weight, storage stability and painting workability will deteriorate, and if the amount added is less than 5.0 parts by weight, the smoothness and water resistance of the coating will deteriorate. It becomes unsuitable for invention.

Among the above-mentioned thickeners, amine salts of carboxyl group-containing acrylic copolymers are particularly preferred (in the present invention) because they make the coating film insoluble in water during heated coating due to elimination of the amine and do not reduce the water resistance of the coating film. be.

The total mixing ratio of water and fine powder resin particles in the coating composition of the present invention is preferably 90-30/10-70.

When the composition has fewer resin particles than the above mixing ratio, the solid content concentration of the paint is low and the viscosity is low, so the thickness of the normal coating film at one time, for example, 20 to 8
When applied to a thickness of 0μ, phenomena such as sagging occur in the coating film, and to avoid this, it is necessary to recoat several times, leading to problems in coating workability.

On the other hand, if the amount of resin particles is greater than the above mixing ratio, it will be difficult to make the paint uniform by stirring, kneading, etc. during paint production, and the viscosity characteristics will not be suitable for various painting methods such as spray painting and electrostatic painting. Since it comes off, painting workability tends to be poor and practicality tends to decrease, which is not preferable.

The water-dispersed thermosetting coating composition of the present invention can be applied by various known methods such as brush coating, dip coating, spray coating, electrostatic coating, curtain flow coating, shower coating, and roll coating. It can be used.

The conditions for heat curing after coating the coating composition vary depending on the content of crosslinkable functional groups in the composition, film thickness, etc.
A cured coating can be formed by heat treatment for 0 to 40 minutes.

The cured coating film thus obtained suppresses temporary rusting on the steel plate, and has excellent adhesion to metal surfaces, corrosion resistance, and water resistance.

In addition, polyester resin has excellent flexibility, pigment dispersibility, and coating appearance, vinyl copolymer resin has excellent hardness and stain resistance, and urethane resin has excellent weather resistance and chemical resistance. In addition, it has excellent coating performance with no bubbling that occurs during high-temperature baking.

The present invention will be explained below with reference to Examples.

Note that "part" or "part" means "part by weight" or "part by weight".

[Method for producing unsaturated polyester resin solution] (1) Unsaturated polyester resin/161 (hereinafter abbreviated as PE-1) Isophthalic acid is added to a reaction vessel equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas introduction tube. 32.6 parts, adipic acid 18.
7 parts, fufuric acid 3.0 parts, neopentyl glycol 2
9.0 parts of Trimethylolp0/Kun were charged, and reacted in a nitrogen gas atmosphere at 225°C for about 8 hours to obtain an acid value of 15.1, a hydroxyl value of 155, and a weight average molecular weight of 6. 700 resin was obtained.

This was diluted with ethyl ketone to a nonvolatile content of 60% to give PE-1.

(2) Unsaturated polyester resin/16.2 (hereinafter PE-
(abbreviated as 2) In a reaction vessel similar to that in which PE-1 was synthesized, 32.3 parts of isophthalic acid, 15.1 parts of adipic acid, and 3 parts of fumaric acid were added.
．． 0 parts, 22.9 parts of neopentyl glycol, 17.4 parts of trimethylolpropane, and 9.3 parts of Cardular E (trade name manufactured by Shell Chemical Co., Ltd.) were reacted at 225° C. for about 8 hours under a nitrogen gas atmosphere. A resin having an acid value of 16.2, a hydroxyl value of 166, and a weight average molecular weight of 4,200 was obtained.

This was diluted with methyl ethyl ketone by 60 parts of the non-volatile content to give PE-2.

(3) Unsaturated polyester resin/16.3 (hereinafter PE-
(abbreviated as 3) in the same manner except that 32.6 parts of ortho-phthalic anhydride was used instead of 32.6 parts of isophthalic acid in PE-1,
Reacted at 225°C for about 6 hours in a nitrogen gas atmosphere to obtain an acid value of 45, a hydroxyl value of 158, and a weight average molecular weight of 2450.
of resin was obtained.

This was diluted with methyl ethyl ketone to a non-volatile content of more than 60% to give PE-3.

[Method for producing polyester modified vinyl resin solution] (1)
1125 parts of methyl ethyl ketone was placed in a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, and a cooling tube, and after raising the temperature to 80°C, the following monomer, polyester resin, and initiator mixture was added dropwise over 3 hours. .

200 parts of methyl methacrylate, 40 parts of styrene, 175 parts of ethyl acrylate, 32.5 parts of 2-hydroxyethyl methacrylate, 5 parts of acrylic acid, 0.25 parts of acidophosphoxyethyl methacrylate, 30 parts of N-n-butoxymethylacrylamide, 30 parts of the polyester resin (PE-1) and 6 parts of azobisisobutyronitrile.

After finishing dropping, add 1 part of azobisisobutyronitrile,
After raising the reaction temperature to 87°C, the reaction was carried out for 4 hours, resulting in an acid value of 8.0, a hydroxyl value of 44, a weight average molecular weight of 90,
500 and a nonvolatile content of 29.9%.

The softening temperature of the resin was about 68-70°C.

This was named PE-PV-1.

(2) Put 1125 parts of methyl ethyl ketone into a reaction vessel similar to that in which PE-PV-1 was synthesized, and adjust the temperature to 80.
After raising the temperature to °C, the following monomer, polyester resin and initiator mixture was added dropwise over a period of 3 hours.

195 parts of methyl methacrylate, 40 parts of styrene, 2-
15 parts of ethylhexyl acrylate, 160 parts of 2-ethylhexyl methacrylate, 35 parts of 2-hydroxyethyl methacrylate, 5 parts of acrylic acid, acidophosphoxyethylmethacrylate.

0.15 parts of tafrylate, 35 parts of N-n-butoxymethylacrylamide, the above polyester resin (PE-2)
25 parts of azobisisobutyronitrile, 6 parts of azobisisobutyronitrile, and 1 part of azobisisobutyronitrile was added after the dropwise addition, and the reaction temperature was raised to 87°C.

After that, the reaction was carried out for 4 hours, and the acid value was 7.9, the hydroxyl value was 42, the weight average molecular weight was 108,500, and the nonvolatile content was 3.
A 0.0% resin solution was obtained.

The softening temperature of the resin was about 67-70°C.

This was named PE-PV-2.

(3) In polyester modified vinyl resin solution production (1), 182.5 parts of ethyl acrylate, N-n-
The same procedure was repeated except that 25 parts of butoxymethylacrylamide, 0.5 parts of acidophosphoxyethyl methacrylate, and 25 parts of the polyester resin (PE-3) were used instead of 30 parts of the polyester resin (PE-1). The reaction was carried out to obtain a resin solution having an acid value of 9.1, a hydroxyl value of 43, a weight average molecular weight of 120.500, and a nonvolatile content of 30.3%.

The softening temperature of the resin was about 68-70°C.

PE-PV-3 was obtained by adding 2 parts and 3 moles of triethylamine to the acid value of the resin solution to neutralize it.

[Solvent replacement method for blocked isocyanate compound] When a blocked isocyanate compound containing a hydrophobic solvent is used, the solvent in the emulsion fine particles is not extracted into water and remains in the resin particles in the process of forming resin particles. For,
This is not preferable because the resin particles coalesce or become integrated, which impairs stability.

Therefore, the blocked isocyanate compound was subjected to solvent substitution using the method described below and used in the present invention.

Takenate B-82ONSU (Kuraide Yakuhin Kogyo Co., Ltd. and local product name: Effective N CO4,3fO1 non-volatile content 60% (solvent Nis-Persol 1500/butyl acetate)) at 440°C
After vacuum drying for 2 days (non-volatile content: 92.61%), methyl ethyl ketone was added.
It was diluted to a non-volatile content of 60 parts to give NC0-A.

[Example 1] To 50 parts of resin solution (PE-PV-1), 12 parts of titanium dioxide and 0.5 parts of flow aid (trade name: Modaflow, manufactured by Monsanto) were added, and the mixture was milled with a sand mill to 10μ or less (grind gauge). After kneading and dispersing the mixture, 50 parts of the resin solution (PE-PV-1), 11.4 parts of the blocked isocyanate compound (NCO-A), and 0.5 part of dibutyltin dilaurate (dissociation catalyst) were added. The mixture was stirred and mixed to obtain a uniform pigment dispersion.

This was dropped into 2000 parts of water at a water temperature of 15° C. under high speed stirring to emulsify the pigment dispersion and extract the solvent into the water to form resin particles.

After that, the tear filtration and water washing were repeated, and the average particle size was approximately 15.
A resin particle water-containing cake with a water content of 0μ and a water content of about 50 was obtained.

Add 40 parts of nonionic surfactant to 100 parts of this water-containing cake.
% aqueous solution (trade name Emulgen 930, manufactured by Kao Atlas Co., Ltd., HLB 15.1), 0.5 parts of a 10% aqueous solution of an alkali salt thickener of an acrylic acid copolymer were added,
The resin particles were pulverized by dispersion and kneading in a sand mill to obtain a slurry-like paint having an average particle diameter of 17 μm and a pH of 7.8.

[Example 2] To 50 parts of resin solution (PE-PV-2), 11.5 parts of titanium dioxide and 0.5 parts of flow aid (trade name: Modaflow, manufactured by Monsanto) were added, and the mixture was milled with a sand mill to a size of 10μ or less. After kneading and dispersing, 50 parts of resin solution (PE-PV-2), blocked isocyanate compound (trade name: Kleran U-I610)
9: Bayer AG) methyl ethyl ketone solution (adjusted to non-volatile content of 50 weight) and 0.5 part of dibutyltin dilaurate (dissociation catalyst) were added and mixed with stirring to obtain a uniform pigment dispersion.

All of the following operations were carried out in the same manner as in Example 1 to obtain a slurry-like paint having resin particles with an average particle diameter of 16 μm and a pH of 7.6.

[Example 3] To 50 parts of resin solution (PE-PV-3), 12 parts of titanium dioxide and 0.5 parts of flow aid (trade name: Modaflow, manufactured by Monsanto) were added, and the mixture was kneaded with a ball mill to 10 μm or less. After dispersion, 50 parts of the resin solution (PE, -PV-3), 10.2 parts of the blocked isocyanate compound (Nco-A), and 0.5 parts of dibutyltin dilaurate (dissociation catalyst) were added and mixed with stirring to form a uniform A pigment dispersion was prepared.

This was sprayed into 3000 parts of water at a water temperature of 20°C under high speed stirring to emulsify the pigment dispersion and extract the solvent into the water to form resin particles.

After that, filtration and water washing were repeated, and the average particle size was 150 μm.
A resin particle water-containing cake with a water content of about 50% was obtained.

Add 40 parts of nonionic surfactant to 100 parts of this water-containing cake.
% aqueous solution (trade name Emulgen 910, manufactured by Kao Atlas Co., Ltd., HLB-122) and 4 parts of a thickener (a 5-module aqueous solution of hydroxyethyl cellulose) were added, and dispersed and kneaded in a ball mill to finely form resin particles. Grind to an average particle size of 16μ
A slurry paint having a pH of 7.5 was obtained.

[Comparative Example 1] Polyester modified vinyl resin solution used in Example 1 (
From the composition of PE-PV-1), the modified polyester resin (
PE-1), the monomer composition excluding acidophosphoxyethyl methacrylate and N-n-butoxymethylacrylamide, and the amount of methyl ethyl ketone as the polymerization solvent was changed to 335 parts. A similar reaction was carried out with an acid value of 8.6,
A resin solution with a hydroxyl value of 32 (weight average molecular weight io, 5oo) and a nonvolatile content of 60.3% was obtained.

To 24 parts of the resin solution, 12 parts of titanium dioxide and a flow aid (
Add 0.5 parts of Modaflow (trade name, manufactured by Monsanto) and 5 parts of methyl ethyl ketone, knead and disperse with a sand mill to a size of 10μ or less, and then add 24 parts of the resin solution and an average degree of condensation of 2.
5. 12 parts of a 60 ratio methyl ethyl ketone solution of a butylated methylolmelamine resin having a degree of etherification of 2.5 and a water-soluble component of 1 part or less, and 5 parts of methyl ethyl ketone were added and mixed with stirring to obtain a uniform pigment dispersion.

The following steps were carried out in the same manner as in Example 1, with an average particle size of 17 μm and p.
A slurry paint of H7,8 was obtained.

[Comparative Example 2] Polyester modified vinyl resin solution used in Example 2 (
From the composition of polyester resin (PE-PV-2)
2), acidophosphoxyethyl methacrylate and N
- The amount of methyl ethyl ketone, which is a polymerization solvent, in the monomer composition excluding n-butoxymethyl acrylamide is 335
The reaction was carried out in the same manner as in polyester-modified vinyl resin solution production (2) except that the reaction was carried out in the same manner as in (2) for producing a polyester-modified vinyl resin solution. I got it.

To this resin solution (24 parts), 12 parts of titanium dioxide, 0.5 parts of flow aid (trade name: Modaflow; manufactured by Monsando), and 4 parts of methyl ethyl ketone were added, and after kneading and dispersing in a ball mill to a size of 10 μm or less, the resin solution was further added. 27 parts and blocked isocyanate compound (trade name Fulleran U-I6109:
Bayer) methyl ethyl ketone solution (non-volatile content: 5
10.8 parts of dibutyltin dilaurate (adjusted to 0% by weight) and 0.5 parts of dibutyltin dilaurate (dissociation catalyst) were added and mixed with stirring to obtain a uniform pigment dispersion.

The following steps were carried out in the same manner as in Example 2, with an average particle size of 15 μm and p
A slurry paint of H7.7 was obtained.

[Comparative Example 3] Polyester modified vinyl resin solution used in Example 1 (
From the composition of PE-PV-1), the modified polyester resin (
The reaction was carried out in the same manner as in polyester-modified vinyl resin solution production (1) except for the monomer composition excluding PE-1) and acidophosphoxyethyl methacrylate, with an acid value of 7.8, a hydroxyl value of 30, and a weight average molecular weight of 18. ,300
A resin solution with a nonvolatile content of 29.2% was obtained.

To 50 parts of the resin solution, 9 parts of titanium dioxide, 0.5 parts of a flow aid (trade name: Modaflow; manufactured by Monsanto), and 0.5 parts of methyl ethyl ketone were added, and after kneading and dispersing in a ball mill to a size of 10 μm or less, the resin was added. 40 parts of the solution was added and stirred and mixed to obtain a uniform pigment dispersion.

The following steps were carried out in the same manner as in Example 1, with an average particle size of 17 μm and p.
A slurry paint of H7.6 was obtained.

The slurry paint prepared in each of the above Examples and Comparative Examples was spray-painted onto a polished mild steel plate, allowed to settle for 5 minutes, preheated at 90°C for 10 minutes, and dried by heating at each predetermined temperature to achieve a film thickness. A coating film of approximately 35 μm was formed.

Table 1 shows the heating drying conditions and physical property test results for the coating film.

From the above comparative test results table, it is clear that the coating film obtained from the coating composition of the present invention does not foam during heat drying and has good impact resistance, chemical resistance, weather resistance, gelation, hard precipitation, etc. Indicates the number of days that will occur.

The cold and heat cycle resistance was very good, and other physical and chemical properties were also as good as those of the comparative examples.

Claims (1)

[Claims] 1 (A) (+) Unsaturated polyester resin.
...2 to 30 weight coefficient (11) (a) N-alkoxymethylated monomer of α, β-monoethylenically unsaturated carboxylic acid amide, (b) phosphoric acid group-containing α, β- monoethylenically unsaturated amniotes, and (
c) A monomer mixture consisting of α,β-monoethylenically unsaturated monomers other than the above (a) and (0)……obtained by weight raft polymerization with a weight ratio of 98 to 70 , hydroxyl value 10-120
fine powder thermosetting resin particles consisting of a polyester-modified vinyl resin and (B) -i-lock isocyanate compound, a surfactant and/or thickener in a weight range of 0.01 to 5.0% relative to the particles; A water-dispersible thermosetting coating composition consisting of an agent and a required amount of water. 2 The mixing ratio of the component (5) and the component (B) is [
The ratio of the hydroxyl group in the component (5) to the isocyanate group in the component (B) is -170.1 to 1/1.2 (ratio in this column). The water-dispersible thermosetting coating composition described in 1. 3 The unsaturated polyester resin has at least 1 to 10
2. The water-dispersed thermosetting coating composition according to claim 1, which contains a β-unsaturated dicarboxylic acid as one of the constituent components. 4 α that graft-polymerizes with the unsaturated polyester resin
, β-monoethylenically unsaturated monomer mixture, (1) hydroxyalkyl ester of α,β-monoethylenically unsaturated carboxylic acid...1 to 15 weight coefficient 1) α,β- N-alkoxymethylated monomer of monoethylenically unsaturated carboxylic acid amide...3-15 weight coefficient ii) IJ acid group-containing α,β-monoethylenically unsaturated monomer... ...0.01 to 1.0 weight range (IV) α other than the above (1), (11) and songs)
, β-monoethylenically unsaturated monomer... 80% by weight or more of the water-dispersed thermosetting coating composition according to claim 1.