JPH11349892A - Aqueous coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aq. coating compsn. excellent in quickly drying properties and storage stability by incorporating a copolymer obtd. from a water-soluble carbonylated unsatd. monomer, a carboxylated unsatd. monomer, a specific free-radial-polymerizable compd., and other free-radical-polymerizable monomers in a specified ratio, a specified amt. of a polyvalent metal, and a hydrazide compd. into the same and by imparting a specified pH to the same. SOLUTION: A copolymer obtd. by the emulsion polymn. of 100 wt.% unsatd. monomer component contg. 0.5-20 wt.% water soluble carbonylated unsatd. monomer 0.5-5 wt.% carboxylated unsatd. monomer, 0.1-10 wt.% compd. represented by formula I and/or formula II having a free-radical-polymerizable double bond in the molecule, and 65-98 wt.% other free-radical-polymerizable unsatd. monomers, a polyvalent metal in an amt. of 0.05-0.5 mol based on carbonyl and carboxy groups in the copolymer, and a hydrazide compd. in an equivalent ratio to CO groups in the copolymer of 0.1-1.5 are incorporated, and a pH of 7-10 is imparted. In the formulas, R1 and R2 are each OCH3 or OC2 H5 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous coating composition, and more particularly, to a coating composition, a synthetic resin, a metal, a glass,
Good stability and fast drying which can be used for various substrates such as ceramics, gypsum, paper, wood, leather, light weight concrete, mortar, calcium silicate board, slates, and gypsum boards It is an aqueous coating composition, and forms a good coating film such as water resistance, alkali resistance, weather resistance, stain resistance, adhesion, and chemical resistance.

[0002]

2. Description of the Related Art Conventionally, organic solvent-based paints have been demanded to be changed to water-based paints in terms of resource saving, energy saving, low pollution, and safety and health. Among water-based resins used for water-based coatings, water-based emulsion resins using surfactants have a high molecular weight and are used in all fields to form excellent coating films even at a relatively low temperature. However, since the solvent is water, ordinary water-based paints have much slower drying properties than solvent-based paints. In the field of paint for building exterior walls, there is a strong demand for water-saving and labor-saving and shortening the construction period. Further, outflow of paint due to pollution or rainfall due to poor drying properties after painting has been regarded as a problem.

[0003] In order to solve these problems, as a method of accelerating the drying property, a method of adding a low-boiling organic solvent, a method of adding a cationic compound or a metal blocked with a volatile base to a resin containing an anionic functional group, or the like. A method of accelerating the drying property by ionic bonding by volatilization of a volatile base and a method of accelerating the drying property by oxidative crosslinking by modifying a resin with a drying oil and adding a metal dryer or the like are also known.

However, these methods have the following problems. The addition of a low-boiling organic solvent is not preferred because the amount of the organic solvent in the coating increases. In addition, the introduction of ionic bonds has a problem in alkali resistance when applied to an alkaline substrate used for building materials and the like. Furthermore, at present, the introduction of oxidative cross-linking has not yet reached the level of quick drying.

[0005]

[Problems to be solved by the invention]

Accordingly, the present invention provides an aqueous solution having an extremely fast drying property while maintaining excellent coating film properties even when applied to an alkaline substrate used for building materials without adding a low boiling point organic solvent. It is an object to provide a coating composition. Here, the extremely fast drying property refers to a degree to which the paint does not flow out upon contact with water after being dried for 30 minutes at a temperature of 5 ° C. and a humidity of 65% after coating.
It is another object of the present invention to provide an aqueous coating composition having excellent coating film properties such as stain resistance, substrate adhesion, warm feeling characteristics, and strength.

[0007]

The first invention comprises a water-soluble unsaturated monomer having a carbonyl group (A), a carboxyl group-containing unsaturated monomer (B), and radically polymerizable in the molecule. The weight ratio of the compound (C) represented by the general formula (1) having an unsaturated double bond and the other radically polymerizable unsaturated monomer (D) is (A) 0.5 to 20% ,
(B) 0.5 to 5%, (C) 0.1 to 10%, (D) 6
A copolymer (E) obtained by emulsion polymerization of a radical polymerizable unsaturated monomer of 5 to 98%, and a carbonyl group and a carboxyl group contained in the obtained emulsion copolymer (E) With respect to 0.05 to 0.5 mol of a polyvalent metal,
An aqueous coating composition comprising a hydrazide compound having an equivalent ratio of 0.1 to 1.5 with respect to a carbonyl group, and further having a pH of 7 to 10.

General formula (1)

[0009]

Embedded image

The second invention is a reactive emulsifier having a radically polymerizable unsaturated double bond in the molecule thereof when the radically polymerizable unsaturated monomer is subjected to emulsion polymerization. The aqueous coating composition according to the first invention, wherein the reactive emulsifier is 0.1 to 10 parts by weight based on 100 parts by weight of the monomer. The third invention is claim 1
Or a cured product using the aqueous coating composition according to 2.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below, but the present invention is not limited to the following description.

The first feature of the present invention is to use a water-soluble unsaturated monomer containing a carbonyl group. This is achieved by emulsion polymerization using a water-soluble unsaturated monomer containing a carbonyl group. A copolymer containing a large amount of a carbonyl group-containing unsaturated monomer can be present on the particle surface. Thus, when water evaporates after coating, the hydrazide compound dissolved in water can be easily crosslinked on the coating film surface, and the paint can be prevented from flowing out upon contact with water. Conversely, when an oil-soluble unsaturated monomer containing a carbonyl group is used, a large amount of the copolymer containing a large amount of the unsaturated monomer containing a carbonyl group is present in the particles, and the cross-linking reaction on the surface of the coating film is slowed to dry. Sex tends to be slow.

The second feature is that a polyvalent metal is added to an emulsion copolymer containing a carbonyl group-containing unsaturated monomer and a carboxyl group-containing unsaturated monomer. Conventionally, there was a problem in alkali resistance due to ionic bond in the case of metal cross-linking using only carboxyl groups, but using a carbonyl group overcomes alkali resistance and finds a coating composition with extremely fast drying properties. I was able to. It is presumed that this is because the carbonyl group and the polyvalent metal form a chelate by a coordination bond. Furthermore, in the case of using only a carboxyl group, if a large amount of carboxyl groups are introduced in order to enhance the drying property, there is a problem that the viscosity is significantly increased upon neutralization. Even in such a case, a carbonyl group can enhance the drying property without any problem.

A third feature is that the general formula (1)
By using the compound represented by the formula, a crosslinked structure can be introduced into the inside of the particles, and the physical properties of the coating film, for example, stain resistance, substrate adhesion, warm feeling characteristics, strength, etc. are improved, and the drying property is improved. As for, the improvement of performance considered to be caused by the good water separation due to the siloxane structure and the hardening of the particles was observed. As described above, by using the three crosslinking systems in combination, it is possible to obtain an aqueous coating composition having excellent drying properties and excellent coating film properties.

The water-soluble carbonyl group-containing unsaturated monomer used in the present invention includes diacetone acrylamide,
It can be selected from one or more of diacetone methacrylamide, acrolein, N-vinylformamide, N-vinylacetamide and the like.

The water-soluble unsaturated monomer having a carbonyl group is used in an amount of 0.5 to 2 per 100 parts of the radically polymerizable unsaturated monomer.
It is desirably 0% by weight. When the amount of the water-soluble unsaturated monomer having a carbonyl group is less than 0.5%, the effect of drying property of the obtained water-based coating composition is hardly observed.
On the other hand, when it is more than 20%, the polymerization stability and the storage stability are deteriorated, and at the same time, the water resistance tends to be inferior due to the increase of the hydrophilic functional groups.

The carboxyl group-containing unsaturated monomer used in the present invention includes polymerizable unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid and anhydrides thereof. Can be selected from one or more.

The content of the unsaturated monomer containing a carboxyl group is desirably 0.5 to 5% by weight based on 100 parts of the radically polymerizable unsaturated monomer. When the content of the carboxyl group-containing unsaturated monomer is less than 0.5%, the mechanical stability and the stability over time of the obtained water-based coating composition are reduced, and the effect of drying property is small. On the other hand, if it is more than 5%, the viscosity at the time of neutralization increases, and the water resistance of the coating film deteriorates.

The compound represented by the general formula (1) having a radically polymerizable unsaturated double bond in the molecule used in the present invention has a hydrolyzable reactive group. Examples that can be used include γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, and the like. One kind or a mixture of two or more kinds can be used.

The compound represented by the general formula (1) is desirably used in an amount of 0.1 to 10% by weight based on 100 parts of a radically polymerizable unsaturated monomer. Preferably, 0.5 to 5% by weight is used. At 0.1% by weight or less, no improvement in the physical properties of the coating film is observed, and no improvement in the drying property is observed. On the other hand, if it is 10% by weight or more, the stability during polymerization is poor,
Also, even if the polymerization can be performed, cracks and the like occur in the coating film.

Other radically polymerizable unsaturated monomers used in the present invention include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, Acrylates such as isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, dodecyl acrylate, methyl methacrylate, propyl methacrylate, n-butyl methacrylate, Isobutyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-methacrylic acid
-Octyl, methacrylates such as decyl methacrylate, dodecyl methacrylate, styrene, vinyl toluene, 2-methylstyrene, t-butylstyrene, styrene-based monomers such as chlorostyrene, hydroxyethyl acrylate, hydroxypropyl acrylate, Hydroxy group-containing monomers such as hydroxyethyl methacrylate, hydroxypropyl methacrylate, N-methylol acrylamide, N-butoxymethyl acrylamide, N-methylol methacrylamide, N-substituted acryl such as N-butoxymethyl methacrylamide, methacrylic monomers, It can be selected from one or more of epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, and one or more such as acrylonitrile.

The other radically polymerizable unsaturated monomer is 65 to 65 parts per 100 parts of the radically polymerizable unsaturated monomer.
It is desirable that the total amount of the unsaturated monomer having a carbonyl group, the unsaturated monomer having a carboxyl group and the compound represented by the general formula (1) is 2 to 35% by weight. That means the same thing. If the total of the carbonyl group-containing unsaturated monomer, the carboxyl group-containing unsaturated monomer and the compound represented by the general formula (1) is less than 2%, the effect is insufficient to say that the drying property is extremely fast, and 35%. If the amount is larger than the above, the stability with the lapse of time tends to deteriorate, and the water resistance tends to decrease.

The aqueous coating composition of the present invention contains a polyvalent metal as a first crosslinking agent. As an addition method, the polyvalent metal salt is dissolved in water before the addition. More preferably, a basic substance is added to the aqueous solution of a polyvalent metal salt to be added as a metal complex. It is also preferable that the pH of the resin solution before the addition of the polyvalent metal is increased in advance.

The polyvalent metals include copper, silver, lithium, beryllium, zinc, aluminum, cobalt, nickel,
Lead, calcium, strontium, barium, titanium,
Vanadium, chromium, manganese, iron, tin, zirconium, molybdenum, magnesium and the like can be used. Also,
These metals can be used in the form of oxides, hydroxides, carbonates, chlorides and the like that can be dissolved in water or basic water.

The amount of the polyvalent metal to be added is from 0.05 to carbonyl groups and carboxyl groups contained in the emulsion copolymer.
Add 0.5 mole of metal. If the amount is less than 0.05 mol, the effect of the drying property does not appear significantly. On the other hand, when the amount is 0.5 mol or more, the stability of the coating material is deteriorated and the water resistance of the coating film is also deteriorated.

Further, a hydrazide compound containing two or more hydrazide groups in the molecule is blended as a second crosslinking agent. As for the method of addition, a water-soluble substance may be added as it is or after dilution with water. Oil-soluble ones are not so preferred in view of the form of the present invention, but when used, it is better to emulsify with a surfactant and add as necessary.

Examples of the hydrazide compound include aliphatic hydrazides such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, and polyhydrazide carbonate, aliphatic, alicyclic, and the like. Aromatic bissemicarbazide, aromatic dicarboxylic acid dihydrazide,
Examples include polyhydrazide of polyacrylic acid, dihydrazide of aromatic hydrocarbon, hydrazine-pyridine derivative, and dihydrazide of unsaturated dicarboxylic acid such as maleic dihydrazide.

The hydrazide compound containing two or more hydrazide groups in the molecule is preferably blended at a ratio of 0.1 to 1.5 equivalents to 1 equivalent of the carbonyl group. When the hydrazide group is less than 0.1 equivalent, the effect of drying property of the aqueous coating composition is poor. On the other hand, if it is more than 1.5 equivalents, the water resistance of the resulting coating film tends to be poor.

The pH of the aqueous coating composition is desirably 7 to 10. When the pH is lower than 7, the storage stability of the resin is deteriorated, and aggregates are generated. On the other hand, when the pH exceeds 10, the amount of the base used for neutralization increases and it takes time to volatilize, and as a result, extremely fast drying property cannot be obtained.

When neutralizing, neutralize with ammonia or an alkylamine such as trimethylamine, triethylamine or butylamine, an alcoholamine such as 2-dimethylaminoethanol, diethanolamine, triethanolamine or aminomethylpropanol, or a base such as morpholine. be able to. However, a highly volatile base is highly effective for drying, and ammonia is the most preferred base.

The reactive emulsifier of the present invention has one or more radically polymerizable unsaturated groups in the molecule, and is, for example, a sulfosuccinate ester (a commercially available product such as Latemul S-120 manufactured by Kao Corporation, S-180P, S
-180A, Sanyo Kasei Co., Ltd. Eleminor JS-2
And alkylphenol ethers (commercially available, for example, Aqualon HS-1 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
0, RN-20, etc.). At the time of emulsion polymerization, one or more of these may be mixed. When the amount of the reactive emulsifier used is small and the emulsification is insufficient, a non-reactive emulsifier can be used in combination, if necessary. As the non-reactive emulsifier, an anionic or nonionic emulsifier used in ordinary emulsion polymerization can be used.

The reactive emulsifier is used in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 7 parts by weight, per 100 parts by weight of the unsaturated monomer.
Use parts by weight. If the amount is less than 0.1 part by weight, the emulsion has poor stability at the time of polymerization and aggregation is likely to occur. When the amount is more than 10 parts by weight, the particle size becomes small, but since a large amount of emulsifier is used, the water resistance of the coating film is deteriorated as an adverse effect.

As the initiator used in the emulsion polymerization, an inorganic peroxide polymerization initiator such as ammonium peroxide and sodium peroxide and a water-soluble azo initiator are used. These initiators can be used alone, or may be used in a redox type in combination with a reducing agent such as sodium ersorbate.

During the emulsion polymerization, transition metal ions such as copper ions such as cupric sulfate and cupric chloride and iron ions such as ferric sulfate and ferric chloride are ^added to the polymerization system in an amount of 10 ⁻⁷ to 10 ⁻⁷ . It can be added in the range of 10 ^-5 mol / l.

Further, sodium acetate, sodium citrate, sodium bicarbonate and the like are used as buffers, polyvinyl alcohol and water-soluble cellulose derivatives are used as protective colloids, and mercaptans such as stearyl mercaptan and t-dodecyl mercaptan are used as chain transfer agents. Can be used.

The aqueous coating composition of the present invention comprises a colorant such as a pigment or a dye, a filler, a thixotropic agent such as finely divided silica, colloidal silica, alumina sol,
Polyvinylpyrrolidone, polyvinyl alcohol, water-soluble polyester resin, water-soluble or water-dispersible polyurethane resin, emulsifier, defoamer, leveling agent, slip agent, tackifier, preservative, fungicide, film-forming aid An organic solvent or the like is blended as needed.

The aqueous coating composition of the present invention can be used mainly as a paint for building exterior walls, but can be used as a printing ink, a coating agent, a paint, an adhesive, a paper material, a fiber material, etc. , Plastic, metal, glass, ceramics, wood, concrete, slate, non-woven fabric, leather,
It can be applied to a base material such as synthetic leather and dried at room temperature or a low temperature of 120 ° C. or lower.

[0038]

The present invention will be described below with reference to examples. In the examples, “parts” and “%” indicate “parts by weight” and “% by weight”, respectively.

Production Example 1 A reaction vessel equipped with a thermometer, a dropping funnel, a reflux condenser, and purged with nitrogen gas was charged with the amount of ion-exchanged water shown in Table 1 in a reactor. The dropping amounts in Table 1 are mixed in advance to prepare a pre-emulsion. After the internal temperature was raised to 80 ° C., dropping was started. While maintaining the internal temperature at 80 ° C., the pre-emulsion was added dropwise over 3 hours, and further reacted at that temperature for 2 hours. After cooling, solid content 51.5%, viscosity 3700 cps,
An aqueous resin dispersion having a pH of 2.4 was obtained.

[0040]

[Table 1]

Production Examples 2 to 9 The compositions shown in Table 2 were polymerized in the same manner as in Production Example 1 to obtain respective aqueous resin dispersions.

[0042]

[Table 2]

Examples 1 to 15

Further, paints shown in Tables 3 and 4 were prepared using the obtained aqueous resin dispersions of Production Examples 1 to 9, and the physical properties of the coating films were evaluated. The coating is made according to the following formulation. The evaluation of the physical properties of the coating film is also shown below. Tables 3 and 4 also show the physical property results of the samples obtained in each test.

Paint Formulation 1. 370 parts of aqueous resin dispersion 2. Primal ASE60 (Nippon Acrylic Co., Ltd. thickener) 4 parts 3. Butyl carbitol 30 parts 4. Sannopco SN-364 (antifoaming agent) 5 parts Ion exchange water 10 parts 6. Polyvalent metal aqueous solution 7. Adipic dihydrazide (crosslinking agent) 8.25% aqueous ammonia (for pH adjustment)

[0046]

[Table 3]

[0047]

[Table 4]

Evaluation of Aqueous Resin Dispersion and Coating Film (1) Polymerization Stability: The amount of resin adhered to the reaction vessel after the completion of the reaction and the amount of aggregates after filtration with a filter cloth were visually evaluated. The evaluation criteria are as follows. ◎: good. ：: This is a level having no practical problem. Δ: The level is slightly problematic. ×: Poor.

(2) Storage stability: The aqueous resin solution was placed in a closed glass container and stored at 40 ° C. for one month, and the rate of change in viscosity was measured. Further, the aggregate at the bottom of the glass container was visually evaluated. The evaluation criteria are as follows. A: Viscosity change rate ≤ ± 10%, no agglomerate observed. ：: Viscosity change rate ≦ ± 10%, and slight aggregation is observed. Δ: Viscosity change rate ± 10% to ± 30%, or some aggregates were observed. ×: Change in viscosity ≧ ± 30% or considerable sedimentation is observed.

(3) Water Whitening Resistance: The coating material prepared above was applied to a glass plate with an applicator and dried at room temperature for 7 days. The coating film obtained was immersed in warm water at 50 ° C. for 1 hour. The degree of whitening was visually evaluated. In addition, evaluation was performed by five-point evaluation. 5 points: No whitening. 1 point: Significant whitening is observed on the entire surface.

(4) Alkali resistance: The coating film prepared above was applied to a glass plate with an applicator and dried at room temperature for 7 days. The coating film obtained was immersed in a saturated aqueous solution of calcium hydroxide for 7 days. Changes were evaluated visually. 5 points: No change at all. 1 point: Significant peeling, whitening, swelling, etc. of the coating film are observed on the entire surface.

(5) Freeze-thaw test: The paint prepared above is applied on a slate plate with a brush in an amount of 400 g / m 2 and dried at room temperature for 7 days. This coated plate is placed in water at 20 ° C for 16
4 hours at -20 ° C in water, 4 hours at 50 ° C in water
The cycle was repeated 10 times, and the condition of the coating film was visually evaluated. In addition, evaluation was performed by five-point evaluation. 5 points: No change is observed. 3 points: Cracks and blisters are partially observed. 1 point: Cracks, blisters, and peeling of the coating film are observed throughout.

(6) Quick-drying property: The above-prepared coating material is applied on a glass plate with an applicator, and then dried at a temperature of 5 ° C. and a humidity of 65%. Water was contacted at intervals of 5 minutes, and the evaluation was made based on the time when the paint stopped flowing.

[0054]

According to the present invention, storage stability is good,
After the coating, the coating is dried for 30 minutes at a temperature of 5 ° C. and a humidity of 65%, so that an aqueous coating composition having an extremely fast drying property in which the coating does not flow out upon contact with water can be obtained. Furthermore, this water-based coating composition has more excellent water resistance,
A coating film having coating film properties such as alkali resistance, substrate adhesion, stain resistance, and film forming property can be formed, and is particularly useful as a paint for building exterior walls.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI C08F 230/08 C08F 230/08

Claims (3)

[Claims] (1) A water-soluble unsaturated monomer having a carbonyl group (A), a carboxyl group-containing unsaturated monomer (B), and a compound having a radical polymerizable unsaturated double bond in the molecule. The weight ratio of the compound (C) represented by 1) and the other radically polymerizable unsaturated monomer (D) is (A) 0.5 to 20%, and (B) 0.5 to 5%. ,
(C) a copolymer (E) obtained by emulsion polymerization of a radically polymerizable unsaturated monomer having 0.1 to 10% and (D) 65 to 98%, and the obtained emulsion copolymer The amount of the carbonyl group and the carboxyl group contained in (E) is 0.
A hydrazide compound having an equivalent ratio of 0.1 to 1.5 with respect to a carbonyl group, and an aqueous solution having a pH of 7 to 10 Paint composition. General formula (1) 2. An emulsifier used when emulsion-polymerizing a radical-polymerizable unsaturated monomer is a reactive emulsifier having a radical-polymerizable unsaturated double bond in a molecule, and the unsaturated monomer is used as an emulsifier. 0.1 to 10 parts by weight of reactive emulsifier
The aqueous coating composition according to claim 1, wherein the amount is part by weight. 3. A cured product using the aqueous coating composition according to claim 1.