JPH0726196A - Water-borne resin composition for coating of high storability - Google Patents

Abstract

PURPOSE:To obtain water-borne resin composition for coating which is used as a printing ink, coating, sealant, adhesive, surface-treating agent or the like because it gives coated and cured product of excellent properties and shows high storage stability. CONSTITUTION:In the presence of a water-soluble resin (a) prepared by neutralizing a resin containing aldo or keto groups and carboxyl groups with ammonia or an organic amine, an ethylenically unsaturated compound (b) is subjected to emulsion polymerization to prepare (A) a resin emulsion containing aldo or keto groups and carboxyl groups. The resin emulsion (A) is combined with (B) a hydrazine derivative having 2 or more hydrazine residues to give the objective water-borne resin composition for coating.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention has excellent storage stability when used as a coating for substrates such as plastic film, metal, paper and glass, that is, as a printing ink, paint, sealant, adhesive, surface treatment agent and the like. The present invention relates to an aqueous resin composition for coating.

[0002]

2. Description of the Related Art As a curable aqueous resin composition for coating, an aqueous dispersion containing a hydrazine derivative and a carbonyl group-containing copolymer such as an aldo group or a keto group is known. These aqueous dispersions have attracted attention because they form a film at a relatively low temperature and have good adhesion to the adherend. For example, Japanese Patent Application Laid-Open No. 54-110248 discloses an aqueous dispersion of a carbonyl group-containing copolymer containing a hydrazine derivative, a composition using a carbonyl group-containing copolymer, an organic hydrazine derivative, and a heavy metal ion. Is described.

An aqueous dispersion composition of carbonyl group-containing copolymer particles is disclosed in Japanese Patent Laid-Open No. 57-3850. The core portion is emulsion-polymerized, and then the shell portion is emulsion-polymerized. A resin having a multi-layer structure is used. JPA
In the aqueous dispersion composition of a carbonyl group-containing copolymer disclosed in JP 57-3857 A, emulsion-polymerized resins having different glass transition temperatures (Tg) are mixed and used. Kohei
JP-A-4-249587 and JP-A-4-372674 disclose, as a resin composition for an aqueous dry-crosslinkable coating composition, a crosslinkable carbonyl group-containing emulsion particle synthesized using a nonionic or anionic activator and a dihydrazide compound. A system consisting of is disclosed.

However, the aqueous dispersions of these resins are all emulsions obtained in the presence of a surfactant. Resins of this type are easy to handle because a resin dispersion with a relatively low viscosity can be obtained even if the molecular weight is increased.
High film formability. However, on the other hand, there are problems that the dispersion stability is poor, the physical properties of the coating film are adversely affected due to the large amount of surfactant, and the coating and printability are insufficient.

[0005]

As a result of intensive studies to solve the above problems, the present inventors have found that an aqueous solution obtained by neutralizing a resin containing an aldo group or keto group and a carboxyl group with ammonia or an organic amine. Of a resin emulsion containing an aldo group or keto group and a carboxyl group obtained by emulsion polymerization of an ethylenically unsaturated compound in the presence of a water-soluble resin, storage stability after coating with a hydrazine derivative in a specific ratio, coating The present invention has been completed by finding out that it has excellent properties in suitability and coating properties after drying.

[0006]

Means for Solving the Problems That is, the present invention is a water-soluble resin obtained by neutralizing a resin containing an aldo group or keto group and a carboxyl group with ammonia or an organic amine.
Resin emulsion (A) containing an aldo group or keto group and a carboxyl group obtained by emulsion polymerization of ethylenically unsaturated compound (b) in the presence of (a), and hydrazine having two or more hydrazine residues Derivative (B) and hydrazine residue 0.1 ~ 5 to 1 equivalent of the aldo group or keto group
Provided is an aqueous resin composition for coating, which is contained in a ratio so as to be equivalent.

In the present invention, a resin prepared by using as a protective colloid a water-soluble resin obtained by neutralizing a resin containing an aldo group or keto group and a carboxyl group instead of a surfactant with ammonia or an organic amine. The aldo group or keto group contained in the emulsion (A) reacts with the hydrazine residue after forming a film by removing water, and forms an excellent coating film.

A resin containing an aldo group or keto group and a carboxyl group is a resin such as styrene or methylstyrene, together with a carboxyl group-containing ethylenically unsaturated monomer and an aldo group or keto group-containing ethylenically unsaturated monomer. Styrenes, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, propyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, (meth) acrylic Carbon number of methoxyethyl acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, methoxyethoxyethyl (meth) acrylate, ethoxyethoxyethyl (meth) acrylate, butoxyethoxyethyl (meth) acrylate 1-18 aliphatic monohydric alcohol, 3-30 carbon atoms ethylene glycol Copolymerization of one or more monomers such as ester of chol monoalkyl ether or diethylene glycol monoalkyl ether having 3 to 30 carbon atoms with (meth) acrylic acid, vinyl acetate, maleic acid ester, acrylonitrile, etc. can get.

Examples of the unsaturated monomer containing a carboxyl group include polymerizable unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid and their anhydrides, which are aldo groups or keto groups. Group-containing unsaturated monomers include acrolein and diacetone (meth)
Acrylamide, formyl styrene, vinyl methyl ketone, vinyl ethyl ketone, vinyl isobutyl ketone,
(Meth) acryloxymethylpropanal, diacetone (meth) acrylate, acetonyl (meth) acrylate, and N-methylol (meth) acrylamide, N-
Examples include N-substituted (meth) acrylic monomers such as butoxymethyl (meth) acrylamide.

The composition of the monomer is such that the amount of the unsaturated monomer containing an aldo group or keto group is 1 to 50% by weight, more preferably 1 to 30% by weight, based on the total amount of the monomer. The acid value of is preferably selected in the range of 70 to 350. When the amount of the unsaturated monomer containing an aldo group or keto group is less than 1% by weight, the cross-linking density of the obtained aqueous resin composition for coating tends to be small and the solvent resistance and water resistance of the coating after drying tend to be slightly inferior. %, The storage stability of the obtained coating aqueous resin composition tends to be slightly low. When the acid value is less than 70, the resin obtained by the following neutralization operation has poor water solubility and the performance as a protective colloid is poor. Further, when the acid value exceeds 350, the water-soluble resin obtained by neutralizing the resin has good performance as a protective colloid, but in the presence of this, a resin emulsion obtained by emulsion polymerization of an ethylenically unsaturated compound The physical properties of the coating film deteriorate. The molecular weight of the water-soluble resin is preferably 3000 to 60,000.

The above-mentioned resin containing an aldo group or keto group and a carboxyl group can be produced by a polymerization method such as bulk polymerization, solution polymerization, emulsion polymerization and suspension polymerization which are well known in the art. For example, in the case of the solution polymerization method, it can be easily produced by polymerizing a predetermined amount of the constituent monomers in the presence of an appropriate organic solvent. As the polymerization initiator, a catalyst such as benzoyl peroxide or azobisisobutyronitrile can be used. If necessary, mercaptans and the like can be added to the reaction system, and the degree of polymerization can be adjusted accordingly.

The resin containing an aldo group or keto group and a carboxyl group obtained as described above has ammonia or triethylamine, trimethylamine, dimethylaminoethanol, monoethanolamine or the like in the reaction system after completion of the polymerization reaction. The desired water-soluble resin (a) can be obtained by adding amines and neutralizing. The addition amount of ammonia or the like is preferably in a range such that the carboxyl group neutralization ratio in the resin is about 70 to 120%. If the neutralization rate is too low, the ability of the resulting water-soluble resin as a protective colloid decreases, which is not preferable.

The resin emulsion (A) containing an aldo group or keto group and a carboxyl group is prepared by mixing the ethylenically unsaturated compound (b) with 100 parts by weight of the water-soluble resin (a) obtained as described above. 20-1000 parts by weight, preferably 50-600
It is obtained by emulsion polymerization of parts by weight. When the ethylenically unsaturated compound (b) is used in an amount less than 20 parts by weight, the content of the water-soluble resin (a) component becomes large, resulting in poor film-forming properties and physical properties of the coating. On the other hand, 1000
When it is used in an amount exceeding the amount by weight, the obtained resin emulsion causes agglomeration and thickening, resulting in poor storage stability. In addition, thixotropy becomes large, and the smoothness of the coating is poor.

The ethylenically unsaturated compound (b) is selected in consideration of hardness, heat resistance, adhesiveness, film-forming property and the like of the obtained coating aqueous composition. Specific examples include (meth) acrylic acid ester having 1 to 22 carbon atoms of an alkyl group, (meth) acrylic acid ester having a hydroxyl group and an amino group, (meth)
Acrylic amide, (meth) acrylonitrile, styrene, (meth) acrylic acid, maleated monoester, etc., acrolein, diacetone (meth) acrylamide, formyl styrene, vinyl methyl ketone, vinyl ethyl ketone, vinyl isobutyl ketone, (meth) Acryloxymethylpropanal, diacetone (meth) acrylate, acetonyl (meth) acrylate and N-
Examples thereof include aldo group- or keto group-containing ethylenically unsaturated compounds such as N-substituted (meth) acrylic monomers such as methylol (meth) acrylamide and N-butoxymethyl (meth) acrylamide.

These compounds may be used alone or in combination of two or more. Examples of the initiator for emulsion polymerization of the ethylenically unsaturated compound (b) include persulfate catalysts such as ammonium persulfate and potassium persulfate, and redox catalysts obtained by combining these with an acidic sulfite. Further, a molecular weight modifier or a surfactant may be added to the emulsion polymerization reaction system of the present invention, if necessary.

The hydrazine derivative (B) having two or more hydrazine residues is a compound having two or more functional groups represented by the following general formula.

[Chemical 1]

Examples of the hydrazine derivative (B) include fatty acid dihydrazides such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, carbonic acid polyhydrazide, aliphatic and alicyclic. Group, aromatic bissemicarbazide, aromatic dicarboxylic acid dihydrazide,
Examples thereof include polyhydrazide of polyacrylic acid, trihydrazide, dihydrazide of aromatic hydrocarbon, hydrazine-pyridine derivative and dihydrazide of unsaturated dicarboxylic acid such as maleic acid dihydrazide and fumaric acid dihydrazide.

The hydrazine derivative (B) having two or more hydrazine residues has 0.1 to 5 equivalents, preferably 0.2 to 5 equivalents of hydrazine residues to 1 equivalent of the aldo group or keto group.
Use in a ratio that provides 3 equivalents. Hydrazine residue
If it is less than 0.1 equivalent, the cross-linking density of the resulting coating aqueous resin composition will be low, and the solvent resistance and water resistance of the coating after drying will be poor. On the other hand, when it exceeds 5 equivalents, the storage stability of the obtained coating aqueous resin composition becomes low.

The aqueous resin composition for coating of the present invention has the above
In addition to (A) and (B), organic or inorganic pigments such as phthalocyanine blue, phthalocyanine green, titanium oxide and carbon black, dyes, calcium carbonate, precipitating barium sulfate, clay and other extender pigments, fine Thixotropic agents such as powdered silica, colloidal silica, sols such as alumina sol, polyvinylpyrrolidone, polyvinylalicol, shellac, water-soluble polyester resin, water-soluble or water-dispersible polyurethane resin or polyamide resin, etc. Resin, emulsifier, defoamer,
A leveling agent, a tackifying resin, a water-soluble or hydrophilic solvent such as ethanol or carbitol, an antiseptic agent, an antifungal agent, etc. are mixed and dispersed, mixed or kneaded by a known disperser, mixer or kneader. To be done.

The aqueous resin composition for coating of the present invention is a gravure printing machine, a flexographic printing machine, a roll coater, a spray coater, a spin coater, a brush, a roller coater, a roll coater, a reverse coater, a knife coater, depending on the purpose. By means such as plastic, paper, metal,
It is printed or applied as a printing ink, paint, sealant, adhesive, surface treatment agent, etc. on a substrate such as wood, glass, concrete, slate, non-woven fabric, leather, synthetic leather, etc., and is heated or dried at room temperature. To be done.

[0021]

EXAMPLES The present invention will now be described in more detail by way of examples. In the examples, "part" means "part by weight" and "%" means "% by weight". [Production Examples 1 to 4] Isopropyl alcohol 300 in a reaction vessel equipped with a stirrer, a thermometer, a dropping device and a reflux condenser.
Then, 200 parts of the monomer mixture having the composition shown in Table 1 and 6 parts of azobisisobutyronitrile were added dropwise over 2 hours, and the mixture was reacted at 83 ° C. for 4 hours. Next, the entire amount of isopropyl alcohol was distilled off under reduced pressure, 600 parts of ammonia water containing an equivalent amount of ammonia to the carboxyl group in the reaction product was added, and an aqueous resin solution containing an aldo group or keto group (solid content 25%) ( a) to (d) were obtained. Table 1
The acid value shown in is the value before neutralizing the resin containing aldo group or keto group with ammonia.

[0022]

[Table 1]

[Production Example 5] 400 parts of the resin aqueous solution (a) was charged in the same reactor as in Production Examples 1 to 4 and heated to 80 ° C. to prepare 25 parts of methyl methacrylate and 25 parts of ethyl hexyl acrylate.
Part and 0.1 part of ammonium persulfate dissolved in 1.9 parts of purified water, 2.0 parts of an aqueous solution is added dropwise over 30 minutes, and then 90 parts.
The mixture was reacted at ℃ for 1 hour, and purified water was added to adjust the solid content to 28%. A keto group-containing resin emulsion (e) having a viscosity of 2400 cps. At 25 ° C was obtained.

[Production Example 6] 400 parts of the resin aqueous solution (b) and 80 parts of purified water were charged in the same reactor as in Production Examples 1 to 4, and
Heated to ℃, 100 parts of methyl methacrylate, methacrylic acid
An aqueous solution obtained by dissolving 0.5 part, 99.5 parts of n-butyl acrylate and 1.0 part of ammonium persulfate in 9.0 parts of purified water.
Parts over 120 minutes, then react at 90 ° C for 1 hour,
Purified water was added to adjust the solid content to 42%. An aldo group-containing resin emulsion (f) having a viscosity of 310 cps. At 25 ° C was obtained.

[Production Example 7] 400 parts of the resin aqueous solution (c) and 400 parts of purified water were charged in the same reactor as in Production Examples 1 to 4.
An aqueous solution obtained by heating to 80 ° C and dissolving 400 parts of n-butyl methacrylate, 200 parts of 2-ethylhexyl acrylate, 3 parts of 2-ethylhexyl thioglycolate as a molecular weight modifier and 1.0 part of ammonium persulfate in 9.0 parts of purified water. The mixture was added dropwise over 150 minutes and then reacted at 90 ° C for 1 hour, and purified water was added to adjust the solid content to 46%. A keto group-containing resin emulsion (g) having a viscosity of 180 cps. At 25 ° C was obtained.

[Production Example 8] 400 parts of the resin aqueous solution (c) and 80 parts of purified water were charged in the same reactor as in Production Examples 1 to 4, and
Aqueous solution obtained by dissolving 20 parts of diacetone acrylamide, 80 parts of methyl methacrylate, 60 parts of n-butyl acrylate, 40 parts of 2-ethylhexyl acrylate, and 1.0 part of ammonium persulfate in 9.0 parts of purified water by heating to ℃. Part was added dropwise for 120 minutes, then reacted at 90 ° C for 1 hour, and purified water was added to adjust the solid content to 44%. Viscosity at 25 ℃ 250cp
A resin emulsion (h) of s. was obtained.

[Production Example 9] A reactor similar to that of Production Examples 1 to 4 was charged with 400 parts of the resin aqueous solution (d) and 80 parts of purified water,
Heated to ℃, 100 parts of methyl methacrylate, methacrylic acid
0.5 part, butyl acrylate 99.5 parts, and ammonium persulfate 1.0 part were dissolved in 9.0 parts of purified water, 10 parts of an aqueous solution was added dropwise over 120 minutes, and then the mixture was reacted at 90 ° C for 1 hour. The minute was adjusted to 42%. A resin emulsion (i) having a viscosity of 1200 cps. At 25 ° C was obtained.

[Examples 1 to 4 and Comparative Examples 1 to 3] Table 2
The composition shown in 1 was mixed to prepare an aqueous resin composition for coating. The obtained coating aqueous resin composition was applied onto an aluminum foil with a wire bar. Table 2 shows the results of evaluation of the appearance state, cellophane adhesiveness, alcohol resistance, alkali resistance and heat resistance of the obtained dry coating film. Table 2 shows the evaluation results of the viscosity stability of the coating aqueous resin composition when stored at 40 ° C for 7 days. The evaluation method and the display of the results are as follows.

[0029]

[Table 2] In the table, RIONOL BLUE FG-7330 is phthalocyanine blue manufactured by Toyo Ink Mfg. Co., Ltd., and Surfynol PC is an antifoaming agent manufactured by Air Products.

Appearance: Visual evaluation. ○: Good, ×: Poor Cellophane adhesiveness ... The degree of peeling with cellophane tape manufactured by Nichiban was visually evaluated. Alcohol resistance: The surface of the coating film was rubbed with absorbent cotton containing 70% ethanol aqueous solution, and the state of the coating film was visually evaluated. Alkali resistance: An aqueous sodium hydroxide solution having a pH of 12.5 was spotted on the coating film for 10 minutes, and the degree of peeling of the coating film was visually evaluated.

Heat resistance: 180 layers of coating and aluminum foil
After pressurizing (2 kg / cm ² ) at ℃ for 0.5 seconds, the aluminum foil was peeled off and the degree of peeling of the coating film was evaluated visually. ⊚: No peeling is observed. ◯: Peeling is slightly observed. Δ: A part of the coating film is peeled off. X: Most of the coating film is peeled off. Storage viscosity stability: ○: viscosity increase of 10% or less, △: viscosity increase of 50% or less, ×: viscosity increase of 100% or less, XX: gelation.

[0032]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain an aqueous resin composition for coating which has excellent physical properties of a cured coating and good storage viscosity stability.

Claims (3)

[Claims] 1. Emulsion polymerization of an ethylenically unsaturated compound (b) in the presence of a water-soluble resin (a) obtained by neutralizing a resin containing an aldo group or keto group and a carboxyl group with ammonia or an organic amine. A resin emulsion (A) containing an aldo group or keto group and a carboxyl group obtained by
Hydrazine derivative having two or more hydrazine residues (B)
An aqueous resin composition for coating, which comprises and in a ratio of 0.1 to 5 equivalents of hydrazine residue with respect to 1 equivalent of an aldo group or keto group. 2. The aqueous resin composition for coating according to claim 1, wherein the resin containing an aldo group or keto group and a carboxyl group has an acid value of 70 to 350. 3. The aqueous resin composition for coating according to claim 1, wherein the ethylenically unsaturated compound (b) is 20 to 1000 parts by weight with respect to 100 parts by weight of the water-soluble resin (a). object.