JPH1112410A - Production of aqueous dispersion composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition which forms coating films excellent in corrosion resistance by mixing an aqueous dispersion containing an ionomer resin with an epoxy-containing compound under heating at a specified temperature. SOLUTION: This composition is obtained by mixing an aqueous dispersion containing 100 pts.wt. ionomer resin with 0.1-100 pts.wt. epoxy-containing compound and optionally a water-soluble amino resin, a curing agent, organic and inorganic thickeners, a surfactant, a rust preventive, etc., under heating at 100-200 deg.C. The ionomer resin is one prepared by neutralizing 20-100% of the side chain carboxyl groups of a copolymer having a main skeleton being an ethylene/unsaturated carboxylic acid copolymer comprising 95-60 pts.wt. ethylene and 5-40 pts.wt. 3-8C unsaturated carboxylic acid (e.g. acrylic acid) with mono or divalent metal cations such as K, Na, Mg or Zn ions. The epoxy-containing compound used is diglycidyl adipate or sorbitan polyglycidyl ether having an epoxy equivalent of 80-2,500 g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aqueous dispersion composition, and more particularly, to an aqueous dispersion composition for forming a coating film having excellent corrosion resistance and good adhesion to a topcoat paint as a metal coating composition. It relates to a method by which a body composition can be obtained.

[0002]

2. Description of the Related Art Ionomer resins, which are composed of a polymer main chain composed mainly of hydrocarbons and are partially neutralized products obtained by neutralizing a part of the carboxyl group in the side chain with a metal cation, have been used in various types of resins. It is well known to have good adhesion to substrates, especially metals. Further, since the coating film made of this ionomer resin is excellent in water resistance, it is also known to use this ionomer resin as a rust preventive for a metal substrate. Furthermore, since ionomer resins can be easily dispersed in water, they are known to be used as aqueous dispersions. Therefore, it is necessary to use an aqueous dispersion containing an ionomer resin as a rust-preventive paint and apply it to a base material such as a metal, for example, a steel sheet to form a rust-proof layer made of the ionomer resin, thereby producing a rust-proof steel sheet. I have been.

[0003] In recent years, with the diversification of uses and higher grades of rust-preventive steel sheets, rust-preventive steel sheets which have been conventionally used only by applying a rust-preventive agent to a base material have been used for coloring. In addition, a coating film made of a curable resin such as a paint is often formed.

[0004]

However, the rust-preventive layer made of an ionomer resin has poor adhesion to a film made of a curable resin such as a paint, so that a paint or the like is overcoated on the ionomer resin film. However, a coating film having good adhesion could not be formed.

Further, in order to increase the efficiency of the production line, it has been required to form a rust-preventive layer at a low temperature in a short time. However, when the formation of the rust-preventive layer is insufficient, the rust-preventive layer may be peeled off by the alkali treatment performed before the top coating, and the composition can form the rust-preventive layer by low-temperature and short-time heating. Things were requested.

Accordingly, an object of the present invention is to provide a method capable of obtaining an aqueous dispersion composition which forms a coating film having excellent corrosion resistance and good adhesion to a topcoat by heating at a low temperature for a short time. To provide.

[0007]

In order to solve the above-mentioned problems, the present invention provides an aqueous solution comprising a step of heating and mixing an aqueous dispersion containing an ionomer resin and an epoxy group-containing compound at 100 to 200 ° C. Disclosed is a method for producing a dispersion composition.

Hereinafter, the method for producing the aqueous dispersion composition of the present invention (hereinafter, referred to as “method of the present invention”) will be described in detail.

The ionomer resin, which is the main component of the aqueous dispersion used in the method of the present invention, mainly comprises a polymer main chain composed of hydrocarbons, has a carboxyl group in a side chain, and has at least one of the carboxyl groups. One part is a polymer neutralized with a metal cation. As a specific example of the ionomer resin, an ionomer resin comprising an ethylene-unsaturated carboxylic acid copolymer, which is a partially neutralized product in which at least a part of the carboxyl group contained therein is neutralized with a divalent metal cation (A-1) can be mentioned.

The ethylene-unsaturated carboxylic acid copolymer constituting the main skeleton of the ionomer resin (A-1) may be a random copolymer or a graft copolymer of unsaturated carboxylic acid onto polyethylene. . Particularly, from the viewpoint of transparency, an ethylene-unsaturated carboxylic acid random copolymer is preferable. Further, the ethylene-unsaturated carboxylic acid copolymer may contain only one kind of unsaturated carboxylic acid or may contain two or more kinds of unsaturated carboxylic acids.

The unsaturated carboxylic acid which is a component of the ethylene-unsaturated carboxylic acid copolymer includes an unsaturated carboxylic acid having 3 to 8 carbon atoms. 3-8 carbon atoms
Specific examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, isocrotonic acid, citraconic acid, allyl succinic acid, mesaconic acid, glutaconic acid, nadic acid, methylnadic acid , Tetrahydrophthalic acid, methylhexahydrophthalic acid, and the like. Among these, acrylic acid and methacrylic acid are particularly preferred.

The ethylene-unsaturated carboxylic acid copolymer constituting the main skeleton of the ionomer resin (A-1) may contain a third component in addition to ethylene and the unsaturated carboxylic acid. Examples of the third component include unsaturated carboxylic esters such as methyl (meth) acrylate, ethyl (meth) acrylate and isobutyl (meth) acrylate, and vinyl esters such as vinyl acetate.

The content of ethylene and unsaturated carboxylic acid in the ethylene-unsaturated carboxylic acid copolymer is usually from 5 to 40 parts by weight of unsaturated carboxylic acid to 95 to 60 parts by weight of ethylene. , Preferably 8 to 25 unsaturated carboxylic acids based on 92 to 75 parts by weight of ethylene.
It is the ratio of parts by weight. When the ethylene-unsaturated carboxylic acid copolymer contains a third component, the third component is preferably present in an amount of 40% by weight or less.

In the ionomer resin, examples of the metal cation that neutralizes at least a part of the carboxyl group in the side chain of the ethylene-unsaturated carboxylic acid include a metal cation having 1 to 3 valences. Among these, a monovalent metal cation is preferable in that an ionomer resin having good emulsifying properties can be obtained. Examples of the metal cation include a monovalent metal ion such as Na, K, and Li, and a divalent metal ion such as Mg, Zn, Cu, Ca, and Ba. Among these, Na,
K, Li, Mg and Zn are preferred.

In the ionomer resin (A-1), the ratio of the carboxyl group neutralized with the divalent metal cation to all the carboxyl groups in the side chain of the ethylene-unsaturated carboxylic acid copolymer, that is, The degree of neutralization is usually about 20 to 100%, and preferably 30 to 80%, in that a rust preventive paint that forms a coating film having excellent corrosion resistance and coating film strength can be obtained. Further, the ionomer resin has an MFR (190 ° C.) according to ASTM D1238.
Is preferably 0.05 to 100 g / 10 min, and particularly preferably 1 to 50 g / 10 min.

The production of the ionomer resin includes, for example,
Ethylene and unsaturated carboxylic acid, and optionally a third
A method in which the components are copolymerized by a high-pressure radical polymerization method, and the carboxyl group of the obtained ethylene-unsaturated carboxylic acid copolymer is neutralized with the compound having a metal cation. The polymerization can be performed according to a method such as a method of neutralizing a carboxyl group of the obtained copolymer with the compound having a metal cation. Further, in this production, a predetermined component may be supplied to an extruder and melted and kneaded to cause a reaction.
Alternatively, it may be performed in an appropriate organic solvent.

Examples of the compound having a metal cation include KOH, NaOH, LiOH, K ₂ C
O ₃ , ZnO, Zn (OH) ₂ , MgO, Mg (OH)
₂ , CuO, Ca (OH) ₂ , Ba (OH) _{2 and the} like.

In the method of the present invention, the aqueous dispersion of the ionomer resin can be easily prepared. Usually, the ionomer resin having a solid content of 1 to 60% by weight with respect to water is mixed with the aqueous dispersion. It can be prepared by a method in which a metal cation is added, and the mixture is heated and melted at a temperature of 100 to 270 ° C. and dispersed.

The epoxy group-containing compound used in the method of the present invention includes, for example, glycidyl esters obtained by reacting carboxylic acid with 2,3-epoxypropanol and the like, and epichlorohydrin and monovalent or polyvalent metal. Glycidyl ethers obtained by reaction with an alkoxide can be exemplified.

Examples of carboxylic acids for obtaining glycidyl esters include saturated monocarboxylic acids such as acetic acid, propionic acid, butyric acid and valeric acid; saturated dicarboxylic acids such as malonic acid, succinic acid, glutaric acid and adipic acid; Aromatic carboxylic acids such as benzoic acid and phthalic acid, unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, isocrotonic acid, citraconic acid, allyl succinic acid, mesaconic acid, glutacon And unsaturated dicarboxylic acids such as acid, nadic acid, methylnadic acid, tetrahydrophthalic acid and methylhexahydrophthalic acid. These carboxylic acids may be used alone or in combination of two or more kinds in the glycidyl esters.

Specific examples of the glycidyl esters used as the epoxy group-containing compound include diglycidyl adipate, diglycidyl phthalate, and diglycidyl terephthalate.

The monovalent or polyvalent metal alkoxide for obtaining glycidyl ethers used as the epoxy group-containing compound is a compound obtained by reacting a monovalent or polyvalent alcohol with a metal. Examples of the monohydric alcohol include methanol, ethanol,
Examples thereof include propanol, butanol, hexanol, and phenol, and examples of the polyhydric alcohol include polyhydric alcohols such as ethylene glycol, resorcin, glycerin, and bisphenol A. Examples of the metal include an alkali metal such as lithium, sodium, magnesium, and calcium or an alkaline earth metal.

Specific examples of the monovalent or polyvalent metal alkoxide include sodium alkoxide. One or a combination of two or more of these metal alkoxides may be contained in the glycidyl ether.

Specific examples of the glycidyl ether used as the epoxy group-containing compound include sorbitol polyglycidyl ether, sorbitan polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, and glycerol polyglycidyl. Ether, trimethylpropane polyglycidyl ether, neopentyl glycol glycidyl ether, ethylene glycol glycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 2,2-bis- (4'-glycidyloxyphenyl) Propane and the like can be mentioned.

In the method of the present invention, the above-mentioned glycidyl esters and glycidyl ethers may be used alone or in combination of two or more as the epoxy group-containing compound.

The epoxy group-containing compound is, for example,
An aromatic epoxy compound represented by a bisphenol A type epoxy compound and a carboxyl group-containing acrylic resin,
A reaction product with an aromatic polyol resin or the like, or a modified epoxy compound may be used.

Further, in the method of the present invention, the epoxy group-containing compound is preferably one which forms a water-soluble or dispersion-forming compound, since the preparation of the aqueous dispersion is easy, and particularly, the compound having a water-soluble ratio of 25% or more. Are preferred. In the present invention, the water solubility refers to the ratio of the amount of the epoxy group-containing compound actually dissolved in water when the epoxy group-containing compound is mixed with water at 25 ° C. That is, a certain temperature T
When the epoxy group-containing compound Xg is dissolved in water at a temperature of Y, when the insoluble portion of the epoxy group-containing compound Yg remains, the water solubility of the epoxy group-containing compound at the temperature T is [(XY) /
X] × 100 (%).

The epoxy group-containing compound preferably has a viscosity at 25 ° C. of 1 to 30,000 mPa · s, particularly preferably 5 to 20,000 mPa · s.

The epoxy group-containing compound used in the method of the present invention preferably has an epoxy equivalent of 80 to 2500 g, particularly preferably 120 to 2000 g. In the present invention, the epoxy equivalent refers to an epoxy group 1
It means the number of grams of epoxy group-containing compound per gram equivalent. For example, when an epoxy group-containing compound having a molecular weight of 100 has one epoxy group in one molecule, the epoxy equivalent of the epoxy group-containing compound is 100. When the epoxy group-containing compound having a molecular weight of 100 has two epoxy groups in one molecule, the epoxy equivalent of the epoxy group-containing compound is 50.

The method of the present invention is a method for producing an aqueous dispersion composition containing an ionomer resin and an epoxy group-containing compound by heating and mixing an epoxy group-containing compound with an aqueous dispersion of an ionomer resin. Heat mixing may be carried out by dissolving the epoxy group-containing compound in the aqueous dispersion of the ionomer resin and heating, or by heating and mixing the aqueous dispersion of the ionomer resin and the aqueous solution or the aqueous dispersion of the epoxy group-containing compound. Is also good.

The temperature during heating and mixing is 100 to 200 ° C.
Preferably it is in the range of 100 to 160 ° C. At a temperature lower than 100 ° C., an aqueous dispersion composition that forms a coating film having sufficient alkali adhesion resistance cannot be obtained, and
If the temperature exceeds 200 ° C., the reaction is performed under a high pressure, which is not preferable in the production operation. The heating and mixing time is not particularly limited, and is usually preferably in the range of 0.5 to 8 hours, and particularly preferably in the range of 1 to 4 hours.

In the method of the present invention, the amounts of the ionomer resin and the epoxy group-containing compound are not particularly limited.
It is appropriately adjusted according to the coating method, the equipment used for coating, and the like. Usually, an amount that gives a total amount of the ionomer resin and the epoxy group-containing compound in the obtained aqueous dispersion composition of 5 to 50% by weight, preferably 10 to 40% by weight can be used.

Further, in the method of the present invention, the ratio of the ionomer resin to the epoxy group-containing compound is not particularly limited, and is appropriately determined according to the molecular weight and epoxy equivalent of the epoxy group-containing compound used. In particular, in terms of being able to obtain an aqueous dispersion composition capable of forming a rust-preventive layer having excellent adhesion with a topcoat paint, when applied to a metal substrate and having corrosion resistance, it is possible to obtain an ionomer resin based on 100 parts by weight. The proportion of the epoxy compound is preferably 0.1 to 100 parts by weight, more preferably 1 to 50 parts by weight.

In the method of the present invention, the aqueous dispersion composition may contain, if necessary, other components such as various resins and compounding agents in addition to the aqueous dispersion of the ionomer resin and the epoxy group-containing compound. You may mix | blend in the range which does not impair the objective of invention. Other components include a water-soluble amino resin,
Hardeners, organic thickeners, inorganic thickeners, surfactants, water-soluble polyvalent metal salts, other rust inhibitors, fungicides, ultraviolet absorbers, heat stabilizers, foaming agents, pigments, fillers, etc. Is mentioned.

The water-soluble amino resin is used for improving the strength of a coating film formed from the aqueous dispersion composition,
For example, a water-soluble melamine resin, hexamethoxy melamine, a methylolated benzoguanamine resin, a methylolated urea resin and the like can be mentioned. Examples of the curing agent include a phenol resin. Further, an organic thickener or an inorganic thickener is used to improve the stability of the aqueous dispersion composition and to adjust the viscosity, and as the organic thickener, for example, polyvinyl alcohol, Examples include polyvinylpyrrolidone, polyvinyl methyl ether, polyethylene oxide, polyacrylamide, polyacrylic acid, carboxymethylcellulose, methylcellulose, and hydroxyethylcellulose. As inorganic thickeners,
For example, silicon dioxide, activated clay, bentonite and the like can be mentioned.

The surfactant is used to improve the stability of the aqueous dispersion composition, and includes, for example, a nonionic surfactant and an anionic surfactant. The rust preventive is used for improving the rust preventive ability of the coating film formed from the aqueous dispersion composition, and examples thereof include water-soluble polyvalent metal salts such as strontium chromate. Further, as the pigment, for example, titanium white, red iron oxide, phthalocyanine, carbon black, permanent yellow and the like, as the filler, for example, calcium carbonate, magnesium carbonate, barium carbonate, talc, aluminum hydroxide, calcium sulfate, Examples include kaolin, mica, asbestos, mica, calcium silicate, and the like.

The aqueous dispersion composition obtained by the method of the present invention can be applied on a substrate, dried and cured to form a coating film having corrosion resistance. The application of the aqueous dispersion composition can be performed by any method such as spraying, curtain, flow coater, roll coater, brush coating, and dipping. After applying the aqueous dispersion composition, the composition may be naturally dried, but is preferably baked. The baking temperature is from 60 to 250 ° C and from 1 to 12
By heating for 0 seconds, a coating film having good corrosion resistance can be formed.

The aqueous dispersion composition obtained by the method of the present invention can form a coating film having excellent corrosion resistance when applied to any substrate, and the substrate is not particularly limited. In particular, examples of a substrate to which the aqueous dispersion composition is applied include a steel sheet such as an untreated steel sheet, a zinc-nickel steel sheet, a tin plate, a zinc iron sheet, and a non-chromate steel sheet.

The coating applied on the coating formed by the aqueous dispersion composition obtained by the method of the present invention is not particularly limited, and examples thereof include melamine alkyd resins and urethane coatings. .

[0040]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, evaluation or measurement of coating film adhesion, alkali adhesion resistance, and corrosion resistance (corrosion rate by salt spray test) of the aqueous dispersion compositions obtained in the following Examples and Comparative Examples were performed by the following methods. So did.

Evaluation method (Preparation of coated steel sheet sample) An aqueous dispersion composition of an ionomer resin was applied to a 0.8 mm thick coated type chromate galvanized steel sheet using a bar coater so that the dry film thickness became 3 μm. Coating, 150 ° C (plate reaching temperature 80 ° C), 10
Baking was performed under the condition of seconds to prepare a coated steel sheet sample for an alkali adhesion resistance evaluation test. Then, to this coated steel sheet sample,
Using a bar coater, a melamine alkyd paint (manufactured by Kansai Paint; Amirac) was dried at a dry film thickness of 35 to 40 μm.
m, baked at 130 ° C. for 20 minutes and cured to obtain a sample for a coating adhesion test of a top coat.

(Coating Film Adhesion) According to the cross-cutting test method described in JIS K 5400, a test piece was prepared by adding a cross-cut to the above-prepared sample for the adhesion test of the overcoat coating film. Then, after the adhesive tape (Nichiban Co., Ltd., trade name cellotape) is stuck on the grid of the test piece, the adhesive tape is immediately pulled in the direction of 90 ° to be peeled, and is not peeled in the grid 100. Count the number of grids,
The value of (number of grids not peeled) / 100 was used as an index for evaluation of coating film adhesion.

(Alkali Resistance to Alkali Resistance) A sample for the evaluation test for the resistance to alkali adhesion was prepared using 2% of pH 10 or more.
Immediately after immersion in sodium silicate water at 60 ° C for 2 minutes,
After washing with water for 0 second and drying with nitrogen gas, the above-mentioned coating film adhesion was evaluated.

(Corrosion Resistance Test-Rust Rate by Salt Spray Test)
At an ambient temperature of 35 ° C., a 5% aqueous solution of NaCl was sprayed on a sample for an alkali adhesion resistance evaluation test, and the white rust generation rate after 240 hours was measured.

(Synthesis Example 1) An ethylene-methacrylic acid copolymer resin (MF) was placed in a 1.5-liter pressure autoclave.
R (190 ° C.): 60 g / 10 min, methacrylic acid content: 20 wt%), 275 g, water 725 g and sodium hydroxide 12.8 g were added.
After stirring for an hour, an aqueous dispersion was obtained. The obtained aqueous dispersion had a solid content of 27.3%, a viscosity of 155 mPa · s,
H9.8.

Example 1 An aqueous dispersion of the ionomer resin obtained in Synthesis Example 1 was mixed with an epoxy group-containing compound (Nagase Chemicals; Denacast EM-101: bisphenol type epoxy emulsion) at a solid content ratio of 10: 1. The resulting mixture was heated and stirred at 130 ° C. for 2 hours to produce an aqueous dispersion composition. The obtained aqueous dispersion composition had a solid content of 26.9%, a viscosity of 50 mPa · s, and a pH of 10. The aqueous dispersion composition was subjected to evaluation of coating film adhesion, alkali adhesion resistance, and corrosion resistance (rust generation rate by salt spray test). Table 1 shows the results.

Comparative Example 1 An aqueous dispersion composition was produced in the same manner as in Example 1 except that the aqueous dispersion of the ionomer resin and the epoxy group-containing compound were mixed at room temperature for 2 hours. The obtained aqueous dispersion composition has a solid content of 2
The product had a viscosity of 8.4%, a viscosity of 150 mPa · s and a pH of 9.7. This aqueous dispersion composition is used for coating adhesion, alkali adhesion resistance and corrosion resistance (rust generation rate by salt spray test).
For evaluation. Table 1 shows the results.

Example 2 An aqueous dispersion was prepared in the same manner as in Example 1 except that a 30% aqueous solution of phenol (EO) ₅ glycidyl ether (Nagase Kasei; Denacol EX-145) was used as the epoxy group-containing compound. A composition was prepared. The obtained aqueous dispersion composition has a solid content of 2
7.3%, a viscosity of 103 mPa · s, and a pH of 9.8. This aqueous dispersion composition is used for coating adhesion, alkali adhesion resistance and corrosion resistance (rust generation rate by salt spray test).
For evaluation. Table 1 shows the results.

Comparative Example 2 An aqueous dispersion composition was produced in the same manner as in Example 2, except that the aqueous dispersion of the ionomer resin and the epoxy group-containing compound were mixed at room temperature for 2 hours. The resulting aqueous dispersion composition had a solids concentration of 27.4.
%, A viscosity of 120 mPa · s and a pH of 9.8. The aqueous dispersion composition was subjected to evaluation of coating film adhesion, alkali adhesion resistance, and corrosion resistance (rust generation rate by salt spray test). Table 1 shows the results.

Example 3 An aqueous dispersion composition was prepared in the same manner as in Example 1 except that a 30% aqueous solution of polyethylene glycol diglycidyl ether (Nagase Chemicals, Denacol EX-861) was used as the epoxy group-containing compound. Manufactured. The obtained aqueous dispersion composition has a solid content of 2
It had a viscosity of 7.4%, a viscosity of 165 mPa · s and a pH of 9.7. This aqueous dispersion composition is used for coating adhesion, alkali adhesion resistance and corrosion resistance (rust generation rate by salt spray test).
For evaluation. Table 1 shows the results.

Comparative Example 3 An aqueous dispersion composition was produced in the same manner as in Example 3, except that the aqueous dispersion of the ionomer resin and the epoxy group-containing compound were mixed at room temperature for 2 hours. The obtained aqueous dispersion composition had a solid content of 27.3.
%, A viscosity of 180 mPa · s and a pH of 9.7. The aqueous dispersion composition was subjected to evaluation of coating film adhesion, alkali adhesion resistance, and corrosion resistance (rust generation rate by salt spray test). Table 1 shows the results.

Comparative Example 4 The aqueous dispersion composition produced in Comparative Example 1 was applied to a 0.8 mm thick coating type chromate galvanized steel sheet using a bar coater.
℃ (plate reaching temperature 130 ℃), baking under the conditions of 10 seconds to form a coating film, to prepare a coated steel sheet sample for evaluation of alkali adhesion resistance, this is the coating film adhesion, alkali adhesion resistance and corrosion resistance (Rust rate by salt spray test). Table 1 shows the results.

[0053]

[0054]

According to the method of the present invention, a coating film having excellent corrosion resistance and good adhesion to a substrate and an overcoat is formed even under a low-temperature, short-time heating film-forming condition. The resulting aqueous dispersion composition can be obtained. Therefore, the aqueous dispersion composition obtained by the method of the present invention is particularly useful as a rust preventive paint for metal substrates.

Claims (2)

[Claims] 1. A method for producing an aqueous dispersion composition comprising a step of heating and mixing an aqueous dispersion containing an ionomer resin and an epoxy group-containing compound at 100 to 200 ° C. 2. The aqueous dispersion composition according to claim 1, wherein the mixing ratio of the ionomer resin and the epoxy group-containing compound is 0.1 to 100 parts by weight of the epoxy group-containing compound per 100 parts by weight of the ionomer resin. Production method.