JP2000226537A - Water-based coating material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-based coating material composition excellent in anti-corrosive properties, water resistance and pot life. SOLUTION: This composition contains (I) an epoxy resin emulsion prepared by dispersing (B) an epoxy resin having an epoxy equivalent within the range of 100-1,000 in water with (A) a modified epoxy resin obtained by reacting (a) a polyethylene glycol having 400-20,000 number-average molecular weight with (b) a bisphenol type epoxy resin, (c) a compound having one active hydrogen in one molecule and (d) a compound having >=2 active isocyanate groups in one molecule as a dispersion stabilizing resin and (II) a carbon dioxide- containing amine curing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to corrosion resistance, water resistance,
The present invention relates to an aqueous coating composition having excellent pot life.

[0002]

2. Description of the Related Art In recent years, there has been a shift from organic solvent-based paints to water-based paints in various paint fields in order to protect the environment and improve working environments, and is being applied to steel structures such as bridges and ships. Various studies have been made also on anticorrosion paints.

As the paint, for example, a two-pack type water-based paint comprising an epoxy resin emulsion base and an amine curing agent has been proposed. However, the conventional paint has a short pot life, and has corrosion resistance, water resistance and curing properties. It was not satisfactory in terms of sex.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that an aqueous coating composition containing a specific epoxy resin emulsion and a carbon dioxide-containing amine curing agent has a pot life. The present inventors have found that a coating film which is long and excellent in corrosion resistance, water resistance, and curability can be formed, and reached the present invention.

That is, the present invention relates to (I) a number average molecular weight of 4
100 to 20,000 polyethylene glycol (a)
A bisphenol-type epoxy resin (b), a compound (c) having one active hydrogen in one molecule, and a compound (c) having one active hydrogen in one molecule.
Compound (d) having at least two active isocyanate groups
An epoxy resin emulsion obtained by dispersing an epoxy resin (B) having an epoxy equivalent in the range of 100 to 1,000 in water using the modified epoxy resin (A) obtained by the reaction of (A) as a dispersion-stable resin, and (II) curing an amine containing carbon dioxide. The present invention provides an aqueous coating composition characterized by containing an agent.

[0006]

DETAILED DESCRIPTION OF THE INVENTION Polyethylene glycol (a) having a number average molecular weight of 400 to 20,000 used in the modified epoxy resin (A) has the following formula: HO (C ₂ H ₄ O) _n H (n = 13 to 714). When the number average molecular weight is less than 400, the hydrophilicity is inferior and the water dispersibility of the resin (A) decreases, while when it exceeds 20,000, the crystallinity of the resin (A) increases, which is not preferable.

The bisphenol-type epoxy resin (b) used in the modified epoxy resin (A) has at least two epoxy groups in one molecule, and particularly includes a bisphenol compound and epihalohydrin. For example, diglycidyl ether of bisphenol obtained by a condensation reaction with epichlorohydrin is preferable from the viewpoint of flexibility and corrosion resistance.

The bisphenol compounds include, for example, bis (4-hydroxyphenyl) -2,2-propane, bis (4-hydroxyphenyl) -1,1-ethane, bis (4-hydroxyphenyl) methane, 4,4 '
-Dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylsulfone, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-
3-t-butylphenyl) -2,2-propane and the like.

In particular, as the bisphenol type epoxy resin (b), bisphenol A type epoxy resin, bisphenol F type epoxy resin and the like can be suitably used. The bisphenol-type epoxy resin (b) has an epoxy equivalent of about 150 to 5000, preferably about 160 to 1.
000 is desirable.

The compound (c) having one active hydrogen in one molecule is used for blocking an isocyanate group in the modified epoxy resin (A). Examples of the compound (c) include monohydric alcohols such as methanol, ethanol and diethylene glycol monobutyl ether; monovalent carboxylic acids such as acetic acid and propionic acid; and monovalent thiols such as ethyl mercaptan. A secondary amine such as diethylamine; a ketone to a primary amino group of an amine compound containing one secondary amino group or a hydroxyl group and one or more primary amino groups such as diethylenetriamine and monoethanolamine; Compounds modified to aldimine, ketimine, oxazoline or imidazoline by reacting with aldehyde or carboxylic acid at a temperature of, for example, 100 to 230 ° C .; oximes such as methyl ethyl ketoxime; phenol, nonylphenol-
And phenols such as phenol. These active hydrogen group-containing compounds (c) generally have a molecular weight of about 30 to 2,000, preferably about 30 to 200.

As the compound (d) having two or more isocyanate groups in one molecule, a conventionally known aliphatic compound,
Alicyclic or aromatic polyisocyanate compounds can be used. For example, hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated 4,4'-diphenylmethane Examples thereof include diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and biuret compounds and isocyanurate compounds thereof. These can be used alone or in combination of two or more.

It is generally appropriate that the reaction ratio of each of the components (a) to (d) be within the following range. The equivalent ratio of the hydroxyl group of (a) to the isocyanate group of (d) is 1 /
1.2 to 1/10, preferably 1 / 1.5 to 1/5, more preferably 1 / 1.5 to 1/3, equivalent of the hydroxyl group of (c) and the isocyanate group of (d). The ratio is 1/2 to 1 /
100, preferably 1/3 to 1/50, more preferably 1/3 to 1/20, of the total amount of the hydroxyl groups of (a), (b) and (c) and the isocyanate group of (d) The equivalence ratio is
1 / 1.5 or less, preferably 1 / 0.1 to 1 / 1.5,
More preferably, the ratio is set to 1 / 0.1 to 1 / 1.1.

The production of the modified epoxy resin (A) is based on mixing the components (a) to (d) and reacting them until substantially no unreacted isocyanate groups are present.

The epoxy resin (B) is an epoxy resin having an epoxy equivalent in the range of 100 to 1,000,
Examples of the epoxy resin (B) include catechol, resorcinol, hydroquinone, bis (hydroxyphenyl) alkane, phenol and novolak of alkylphenol, phenol and alkylphenol.
Diglycidyl ethers of polyvalent phenols such as novolak of dioxnaphthalene, naphthalene and alialkylnaphthalene, resole of naphthalene and alialkylnaphthalene, novolak of phenol and naphthalene, cresol and resol of naphthalene -Ter; triglycidyl ether ester of hydroxybenzoic acid; diglycidyl ester of isophthalic acid, terephthalic acid, dicarboxyalkane, polymerized fatty acid, etc .; glycidylated compound of benzylamine, alkylbenzylamine; triglycidylated compound of aminophenol; Tetraglycidylated diamines;
Glycidylated compounds such as phenol and aniline, cresol and aniline, cresol and alkylaniline;
Dihydroxycyclohexane, bis (hydroxycyclohexyl) methane, bis (hydroxycyclohexyl)
Propane, bis (hydroxycyclohexyl) butane,
Multivalent alcohols such as ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, polyethylene glycol, and polypropylene glycol
Diglycidyl ether; trimethylolpropane;
Polyvalent alcohols such as glycerin and pentaerythritol
Polyglycidyl ether; terminal isocyanate compound which is a reaction product of polyoxyalkylene glycol and diisocyanate with bisphenol A or bisphenol-
And a reaction product with F-diglycidyl ether.

The epoxy resin emulsion (I) used in the present invention is obtained by using the modified epoxy resin (A) as a dispersion-stable resin and dispersing the epoxy resin (B) in water. The use ratio at the time of dispersion is suitably (A) / (B) in the range of 50/50 to 80/20 in terms of solid weight, and can be obtained by adding water to both and mixing and stirring.

In the present invention, the carbon dioxide-containing amine curing agent (II) is obtained by bringing carbon dioxide into contact with polyamines. The form of the carbon dioxide may be any of gas, liquid and solid. By carbonating the amino group in the polyamine, the reaction with the epoxy group is blocked, and the pot life can be extended. After the film is formed, carbon dioxide is volatilized and hardened immediately.

Examples of the polyamines include aliphatic polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, dimethylaminopropylamine and diethylaminopropylamine; isophoronediamine, 1,4-diaminocyclohexane, bis- (amino Alicyclic polyamines such as methyl) cyclohexane and N-aminoethylpiperazine; aromatic polyamines such as meta-xylylenediamine and phenalcamine; Mannich products of these polyamines;
Modified polyamines such as epoxy adducts and polyamidoamines are exemplified. Polyamidoamine is particularly preferable because it is difficult to crystallize in an aqueous solvent when carbonated.

The amount of carbon dioxide used for the polyamines is 1 to 30 carbon dioxide based on the weight of the polyamine.
%, Preferably 2 to 10% by weight. If the amount is less than 1% by weight, sufficient corrosion resistance, water resistance and pot life cannot be obtained, while if it exceeds 30% by weight,
The crystallization of the polyamine is remarkable, and it is not preferable because it cannot be sufficiently mixed with the epoxy resin base material and a uniform coating film cannot be obtained.

If necessary, the carbon dioxide-containing amine curing agent (II) may be used in combination with carbon dioxide-free polyamines as exemplified above.

In preparing the composition of the present invention, the use ratio of the epoxy resin emulsion (I) and the amine curing agent (II) is such that the molar ratio of active hydrogen in the amine to the epoxy group in the epoxy resin is 0.2. ~ 1.5, preferably 0.4 ~
It is selected to be within the range of 1.0. If the molar ratio is less than 0.2, the curing is insufficient, and the corrosion resistance and water resistance are poor. On the other hand, if the molar ratio exceeds 1.5, unreacted amine remains in the coating film even after the curing and lowers the water resistance. Is not preferred.

The composition of the present invention further comprises, as a flash-last inhibitor when applied on an iron surface (especially on a rust-remaining surface), at least one selected from water-soluble metal nitrites, phytates and ethylenediaminetetraacetate. One type can be contained. These are all water-soluble salts, and each anion present as an electrolyte reacts with iron ions adsorbed or eluted on the iron surface, forming a water-insoluble complex film and preventing further iron oxidation. Specific examples thereof include, for example, sodium nitrite, sodium phytate, potassium phytate, sodium ethylenediaminetetraacetate, potassium ethylenediaminetetraacetate, calcium nitrite, strontium nitrite, barium nitrite and the like.

It is preferable that the flash last inhibitor is added to the coating liquid in an amount of 0.02 to 2% by weight, preferably 0.05 to 1% by weight. If the amount is less than 0.02% by weight, flash rust cannot be suppressed, and spot rust occurs immediately after coating, resulting in a poor appearance of the coating film. Is significantly reduced.

The composition of the present invention may further comprise, if necessary,
Pigments such as coloring pigments, extender pigments, and rust-preventive pigments which are usually used in the field of coatings; curing catalysts, surfactants, defoamers,
Paint additives such as a pigment dispersant, an antisettling agent, a thickener, an organic solvent, a film forming aid, and a coating surface adjuster;
Other aqueous resins can be blended.

The composition of the present invention obtained as described above is a two-pack paint comprising a paint base containing an epoxy resin emulsion (I) and an amine curing agent (II). Things. As a coating method, conventionally known methods such as spray coating, roller coating, and brush coating can be adopted.

[0025]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. “Parts” and “%” are “parts by weight” respectively.
And "% by weight".

Production Example 1 of Water-Based Epoxy Resin Paint Base Material In a glass four-necked flask equipped with a thermometer, a stirrer, and a condenser, polyethylene glycol having a number average molecular weight of 4,000 was added.
600 g (0.15 mol) of propylene glycol 13.5 g (0.15 mol) of propylene glycol and "Epicoat 828" (manufactured by Yuka Shell Epoxy Co., Ltd., bisphenol A type epoxy resin, epoxy equivalent 190) ) 380g
(1 mol) was added, and the mixture was stirred and mixed at 100 ° C. to obtain a uniform mixture. Then, 52.2 g (0.3 mol) of tolylene diisocyanate was added, and the mixture was reacted for 2 hours. ,
The reaction was continued for another 4 hours. Then, it was confirmed that the isocyanate value was 0.5 or less.
One obtained by adding 117 g of lumonomethyl ether and diluting the mixture was designated as a dispersion-stable resin (A-1).

To 35 parts of this dispersion-stable resin (A-1), 65 parts of "Epocoat 828" was added, and 100 parts of water was added while stirring with a stirrer to give an epoxy resin emulsion (I) having a solid content of 50%. -1) was obtained. Its epoxy equivalent was 497.

This epoxy resin emulsion (I-1)
47 parts, "TR-92" (titanium white, Tioxide UK Lim
13 parts, “Talc No. 1” (Talc, manufactured by Takehara Chemical Industry Co., Ltd.) 22.85 parts, “Nopco Santo K” (pigment dispersant, manufactured by San Nopco), 1 part, “SN Deformer-31”
3 "(antifoaming agent, manufactured by San Nopco), 0.1 part of" Suraoff S "(preservative, manufactured by Takeda Pharmaceutical Co., Ltd.) and 0.05 part of water, and stirred and mixed with a stirrer to homogenize. After that,
The particles were dispersed to a particle size of 40 μm (distribution diagram) using a paint shaker to obtain a water-based epoxy resin paint base material.

Preparation Example 2 In Preparation Example 1, instead of 600 g of polyethylene glycol having a number average molecular weight of 4,000, a number average molecular weight of 1
1,500 g of polyethylene glycol of 000
(A-2) was obtained in the same manner as in Production Example 1 except that (0.15 mol) was used. This dispersion stable resin (A
-2) 65 parts of "Epocoat 828" was added to 35 parts, and 100 parts of water was added while stirring with a stirrer to obtain an epoxy resin emulsion (I-2) having a solid content of 50%.
This had an epoxy equivalent of 532.

This epoxy resin emulsion (I-2)
47 copies, "TR-92" 13 copies, "Kure-special name W"
(Cray, manufactured by Takehara Chemical Industry Co., Ltd.) 22.85 parts, “Nopco Santo K” 1 part, “SN Deformer-313” 0.1
Parts, "Slaoff S" 0.05 parts and water 16 parts,
Stir and mix with a stirrer to make uniform, then paint
The particles were dispersed to a particle size of 40 μm (distribution diagram) using a car to obtain a water-based epoxy resin paint base material.

Production Example 3 In Production Example 1, 52.2 tolylene diisocyanate was used.
66.7 g of isophorone diisocyanate instead of g
(S-3) A dispersion-stable resin (A-3) was obtained in the same manner as in Production Example 1 except that (0.3 mol) was used. This dispersion stable resin (A-
3) 65 parts of "Epocoat 828" was added to 35 parts, and 100 parts of water was added while stirring with a stirrer to give a solid content of 5 parts.
A 0% epoxy resin emulsion (I-3) was obtained. Its epoxy equivalent was 498.

This epoxy resin emulsion (I-3)
In 47 parts, 13 parts of "TR-92", 22.85 parts of "LW350" (calcium carbonate, manufactured by Yabashi Kogyo), 1 part of "Nopcosanto K", 0.1 part of "SN deformer-313" 0.1
Parts, "Slaoff S" 0.05 parts and water 16 parts,
Stir and mix with a stirrer to make uniform, then paint
The particles were dispersed to a particle size of 40 μm (distribution diagram) using a car to obtain a water-based epoxy resin paint base material.

Production Example 4 In Production Example 1, the blending amount of the dispersion stable resin (A-1) and "Epocoat 828" was
An epoxy resin emulsion (I-4) having a solid content of 50% was obtained in the same manner as in Production Example 1 except that 0 parts and 80 parts of "Epocoat 828" were used. The epoxy equivalent of this is 43
Nine.

This epoxy resin emulsion (I-4)
47 parts, 10 parts of "Todakara-520R" (Vengara, manufactured by Toda Kogyo Co., Ltd.), 22.85 parts of "Talc 1", 1 part of "Nopco Santo K", 0.1 parts of "SN deformer-313"
Parts, "Slaoff S" 0.05 parts and water 16 parts,
Stir and mix with a stirrer to make uniform, then paint
The particles were dispersed to a particle size of 40 μm (distribution diagram) using a car to obtain a water-based epoxy resin paint base material.

Comparative Production Example 1 "VEP-238" was used as an epoxy resin emulsion.
5 "(manufactured by Hoechst Co., Ltd., epoxy resin emulsion, epoxy equivalent: 911).
92 ”13 parts,“ Talc No. 1 ”22.85 parts,“ Nopcosanto K ”1 part,“ SN Deformer-313 ”0.1
Parts, "Slaoff S" 0.05 parts and water 16 parts,
Stir and mix with a stirrer to make uniform, then paint
The particles were dispersed to a particle size of 40 μm (distribution diagram) using a car to obtain a water-based epoxy resin paint base material.

Comparative Production Example 2 To 70 parts of "Epicoat 828", 30 parts of "Nonipol 100" (manufactured by Sanyo Kasei Co., Ltd., polyoxyethylene phenyl ether) and 100 parts of water were added as emulsifiers. A resin emulsion was prepared. Its epoxy equivalent was 543.

In 47 parts of the epoxy resin emulsion,
"TR-92" 13 parts, "Talc 1" 22.85 parts,
"Nopco Santo K" 1 copy, "SN Deformer-313"
0.1 parts, 0.05 parts of "Sluroff S" and 16 parts of water were added, and the mixture was stirred and mixed with a stirrer to make uniform, and then dispersed with a paint shaker to a particle size of 40 μm (distribution diagram).
An aqueous epoxy resin paint base was obtained.

Preparation of Carbon Dioxide-Containing Amine Curing Agent “Ancamide 365” (modified polyamidoamine containing 3 to 4% carbon dioxide, manufactured by Air Products, active hydrogen equivalent 240) was used as a curing agent (II-1). Further, 1,000 g of the “ankamide 365” was added to a thermometer, a stirrer,
Charged into a glass four-necked flask equipped with a cooling tube,
Carbon dioxide gas was blown into the liquid while stirring at ℃. When the weight increases by 5%, stop blowing carbon dioxide gas.
A curing agent (II-2) containing 8 to 9% of carbon dioxide was used.

Further, "Ankamide 260A" (polyamide amine, manufactured by Air Products, active hydrogen equivalent 12
0) was replaced with a curing agent (II-3), "Ditoclar 1301"
S "(epoxy adduct of meta-xylene diamine, manufactured by Daito Sangyo Co., Ltd., active hydrogen equivalent: 96) was used as a curing agent (II-4).

Preparation of Water-based Coating Compositions Examples 1 to 10 and Comparative Examples 1 to 9 The main components and the curing agent of the water-based epoxy resin coating obtained in each of the above-mentioned production examples, and a flash-last inhibitor in the proportions shown in Table 1 By mixing, each aqueous coating composition was obtained. The flash last inhibitors used are: a: sodium nitrite, b: sodium phytate, c: sodium ethylenediaminetetraacetate.

Next, each composition was subjected to the following performance tests. Table 1 shows the test results.

Performance Test (1) Corrosion Protection: The composition obtained above was applied on a polished steel plate with a doctor blade so as to have a dry film thickness of 40 to 50 μm, and was applied at 20 ° C. and 65% RH. Each test coated plate was prepared by drying in an atmosphere for 7 days. The test coated plate was cross-cut with a knife on the coated surface and subjected to a salt spray test according to JIS-Z-2371 for 336 hours. The occurrence of rust and blisters was visually observed (（: no abnormality, ○: rust Some swelling occurs,
X: Rust and blisters are remarkably generated).

(2) Water resistance: A test coated plate prepared in the same manner as in the above (1) was immersed in deionized water for 30 days.
The state of the coated surface was observed immediately after and two hours after the removal (◎: no abnormality, ○: wrinkles and blisters were partially observed immediately after the removal, but no gloss change or clouding was observed two hours after the removal. X: Wrinkles and blisters are remarkably observed immediately after the removal, and gloss and fogging are significantly observed after 2 hours).

(3) Pot life: 20% of the composition obtained above was used.
After storage at 8 ° C. for 8 hours, the composition was applied on a polished steel plate with a doctor blade to a dry film thickness of 40 to 50 μm, and dried at 20 ° C. and an atmosphere of 65% RH for 24 hours. Was visually observed (o: no abnormality, x: poor).

(4) Curability: The composition obtained above was coated on a polished steel plate by a doctor so as to have a dry film thickness of 40 to 50 μm.
The composition was applied with a blade, and the curability was evaluated from the degree of drying in an atmosphere of 20 ° C. and 65% RH (◎: cured and dried in 12 hours, ：: cured and dried in 16 hours, Δ: semi-cured in 16 hours,
×: Touch dry in 16 hours).

(5) Suppression of flash blast: As a test plate, a plate obtained by exposing a sand blast plate in a seaside area for 6 months and generating rust on the entire surface was used as a Keren grade St2.

The composition obtained above was applied to this test plate with a doctor blade so as to have a dry film thickness of 40 to 50 μm, and was applied after drying at 20 ° C. and an atmosphere of 65% RH for an hour. AS the flash rust area generated on the surface
Evaluation was performed according to TM D610-68 (A: 10 to 9).
Points, ：: 8-7 points, Δ: 6-5 points, ×: 4-1 points).

[0048]

According to the present invention, a two-pack aqueous coating composition having a longer pot life than before can be obtained, and a coating film having good adhesion, water resistance and corrosion resistance can be formed. Further, by combining a specific water-soluble rust inhibitor, it is possible to significantly suppress flash blast on the iron surface (especially on the rust remaining surface).

[0049]

[Table 1]

Continued on the front page (72) Inventor Kenichi Tomita 4-171-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa F-term in Kansai Paint Co., Ltd. 4J036 AA01 AB01 AB02 AB03 AC01 AC02 AC05 AD08 AD15 AD21 AF05 AF06 AF08 AG07 CA02 CB20 CC01 CD12 DC02 DC06 DC09 DC10 FA04 FA14 JA01 KA04 4J038 DB002 DB421 DB481 GA07 HA336 JB04 JB08 KA03 MA08 MA10 MA14 NA03 NA04

Claims (2)

[Claims] (I) a number average molecular weight of 400 to 20,000
0, a polyethylene glycol (a), a bisphenol-type epoxy resin (b), a compound (c) having one active hydrogen in one molecule, and two or more active isocyanates in one molecule An epoxy resin emulsion obtained by dispersing an epoxy resin (B) having an epoxy equivalent in the range of 100 to 1,000 in water with the modified epoxy resin (A) obtained by the reaction of the compound (d) having a group as a dispersion-stable resin, and II) An aqueous coating composition comprising a carbon dioxide-containing amine curing agent. 2. The aqueous coating composition according to claim 1, which contains at least one selected from the group consisting of water-soluble metal nitrites, phytates, and ethylenediaminetetraacetates as a flash-last inhibitor.