JPS6145669B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aqueous coating composition that is curable at room temperature and has improved water and solvent resistance. In recent years, there has been a desire for paints that use water as a medium to replace solvent-based paints from the standpoint of hygiene, fire risk, air pollution, economic efficiency, etc. However, no practical water-based paints that cure at room temperature have yet appeared. Water-soluble resins that have been published so far include dry oil-modified alkyd or polybutadiene types containing carboxyl groups, but these require an excess of carboxyl groups to achieve water solubility. As a result, the water resistance of the paint film after drying is poor, causing problems in outdoor painting. The present invention relates to a water-based coating composition that eliminates the drawbacks of conventional water-based resin paints and is intended to provide a coating film comparable in performance to that obtained from conventional oil-based paints at room temperature. That is, the present invention provides (A) a compound having in one molecule an air-drying unsaturated double bond and a functional group capable of reacting with a carboxyl group; and (b) an ethylenically unsaturated polybasic carboxylic acid. or its anhydride in a proportion such that at least one carboxyl group remains.
70 parts by weight, and (B) 99.5 parts of a vinyl monomer whose main component is an acrylic monomer that can be copolymerized with the above component A.
The present invention provides an aqueous coating composition obtained by emulsion copolymerization of ~30 parts by weight in an aqueous medium. Component (A) in this aqueous coating composition has multiple functions as an air-curable copolymerizable emulsifier with unsaturated double bonds, so the copolymer in which this component is copolymerized is self-emulsifying. It is an ideal resin that is flexible and air curable. Component (a) that constitutes component (A) refers to a functional group that can react with an air-drying unsaturated double bond and a carboxyl group such as a hydroxyl group, an amino group, an epoxy group, an isocyanate group, or an anhydride group thereof. The following compounds are compounds containing a group in one molecule. (Those with air-drying unsaturated double bonds are simply referred to as unsaturated hereinafter.) (a) Unsaturated fatty acid diglycerides, unsaturated fatty acid hydroxyalkyl esters (b) Reaction products between unsaturated fatty acids and amino alcohols hydroxyalkyl unsaturated fatty acid amides (c), which are monoamides of unsaturated fatty acids with one amino group remaining, polyamides such as diamides (d), reaction products of unsaturated fatty acids and polyepoxides with one epoxy group remaining; Glycidyl unsaturated monocarboxylic acid ester, 3-chloro-2-hydroxypropyl unsaturated monocarboxylic acid ester produced from unsaturated monocarboxylic acid and epichlorohydrin (e) Unsaturated fatty acid with one remaining isocyanate group and di- or tri- Reaction products of isocyanates (f) Unsaturated primary alcohols (g) Reaction products of unsaturated fatty acids and ethyleneimine or propyleneimine These air-drying unsaturated fatty acids include drying oil fatty acids, sorbic acid, and allyl alcohol. There are semi-phthalic acid esters, etc. In addition, unsaturated primary alcohols include ethylene oxide adducts, propylene oxide adducts of allyl alcohol,
Unsaturated aliphatic alcohols such as glycerin allyl ether and oleyl alcohol. The unsaturated fatty acid hydroxyalkyl ester (a) is a compound mainly having a hydroxyl group at the end, and is a compound synthesized by adding an unsaturated fatty acid and ethylene oxide or propylene oxide. The hydroxyalkyl unsaturated fatty acid amide in (b) is an unsaturated fatty acid amide with a hydroxyl group at the end synthesized from an amino alcohol such as monoethanolamine or hydroxypropylamine and an unsaturated fatty acid; The polyamide, such as unsaturated fatty acid monoamide, which remains is a compound represented by the following formula. (R: Air-drying unsaturated aliphatic group) (d) Reaction products of unsaturated fatty acids with one remaining epoxy group and polyepoxides include ethylene glycol, diethylene glycol, propylene glycol, glycerin, bisphenol A, etc. It is a compound obtained by leaving one epoxy group of diepoxide or triepoxide obtained from a dihydric or trihydric alcohol and epichlorohydrin and reacting the other epoxy group with an unsaturated fatty acid. Next, (e), the reaction product of an unsaturated fatty acid with one remaining isocyanate group and a di- or triisocyanate is hexamethylene diisocyanate, diphenylmethane diisocyanate, or tolylene diisocyanate, and the reaction product of these with trimethylolpropane. It is a compound obtained by reacting a trifunctional triisocyanate, etc., with an unsaturated fatty acid such that one isocyanate group of these polyisocyanates remains. In addition, the ethylenically unsaturated polybasic carboxylic acids of component (b) include maleic acid, fumaric acid, itaconic acid, and their acid anhydrides, allylmaleic acid, citraconic acid, glutaconic acid, mesaconic acid, and 3-butene. 1.2.3-Tricarboxylic acids, etc. One or more selected from the above components (a) and one or more components (b) are reacted in a proportion such that one or two carboxyl groups of component (b) remain. The resulting product is neutralized with a basic substance to form a basic salt and to make it water-soluble. Suitable basic substances include sodium hydroxide, potassium hydroxide, lithium hydroxide, aqueous ammonia, mono, di, trimethylamine, mono, di, triethylamine, mono, di, tripropylamine, mono, di, triethanolamine, etc. It is. The present invention uses these components (A) as a new copolymerizable emulsifier with air-drying properties by copolymerizing them with vinyl monomers mainly composed of other acrylic monomers. Sexually and chemically,
The object of the present invention is to obtain an aqueous resin dispersion with excellent mechanical stability. The amount of component (A) used is
A suitable amount is 0.5 to 70 parts by weight, preferably 3 to 20 parts by weight per 100 parts by weight. If the amount is less than 0.5 parts by weight, the effect on the stability of the resin dispersion will not be sufficient, and if it is more than 70 parts by weight, the properties of the resin will change significantly, which is not preferable. In the present invention, the acrylic monomer of component (B) includes (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and hydroxyethyl (meth)acrylate. , hydroxypropyl (meth)acrylate, (meth)acrylamide, and the like. Other styrene, α-methylstyrene, (meth)
A small amount of a vinyl monomer such as acrylonitrile, vinyl chloride, vinylidene chloride, or vinyl acetate may also be used in combination. In the emulsion polymerization of the present invention, ordinary water-soluble peroxide catalysts such as potassium persulfate, ammonium persulfate, or hydrogen peroxide are used, and it is also effective to use acidic sodium sulfite or acidic ammonium sulfite as a reducing agent. The polymerization can be completed with good yield in the range of 40°C to 85°C. The concentration of resin dispersion is 25
% to 70%, preferably 40% to 60% is optimal. The resin dispersion of the present invention is sufficiently stable with or without a small amount of emulsifier, and there is no problem in workability under normal coating conditions. Emulsions made with emulsifiers tend to foam. When using, use a regular dryer, such as cobalt salts, zirconium salts, lead salts such as octylic acid and naphthenic acid,
A manganese salt or the like is dissolved in a solvent such as butylcellosolvel and added. The amount of dryer used is preferably about 20.1 to 3% based on the resin content. The resin dispersion of the present invention has a low viscosity and can be highly concentrated,
The coating film, which is crosslinked at room temperature, exhibits water resistance, solvent resistance, and chemical resistance, and has excellent hardness and adhesion. A wide range of objects can be coated, including metal and wood. When used, common film-forming aids such as butyl cellosolve, texanol, etc. can be used in combination, and titanium white and other extender pigments can be widely used. Examples will be shown below, where parts represent parts by weight. Example 1 Separately from a 10% aqueous solution of 20 parts of maleic acid half ester of dehydrated castor oil fatty acid diglyceride neutralized with potassium hydroxide, a mixed monomer of 40 parts of methyl methacrylate, 40 parts of butyl acrylate, and 2 parts of acrylic acid was prepared, First, 50 parts of ion-exchanged water was charged into a 500 ml four-necked kolben equipped with a reflux condenser, thermometer, dropping funnel, and stirring rod, and then 0.5 part of ammonium persulfate was charged, and when the internal temperature rose to 78°C, While stirring, the monomer and a 10% aqueous solution of potassium hydroxide neutralized maleic acid half ester of dehydrated castor oil fatty acid diglyceride are simultaneously added dropwise. During this time, the internal temperature is maintained between 78 and 82 degrees Celsius. After dropping for 3 hours, the internal temperature was maintained at 85°C for 1 hour to complete the reaction. Emulsified dispersion with resin concentration of 30% is 332
Part was obtained. The polymerization yield was 98.5%. Next, aqueous ammonia was added to neutralize the resulting emulsified dispersion until the pH reached 8.0. 20% to the emulsion
butyl cellosolve solution of cobalt naphthenate
The film was coated on a glass plate with 1.5% added and left at room temperature for 48 hours. When the film was tested for troll resistance, ethyl acetate resistance, and acetone resistance, it swelled slightly but did not dissolve. On the other hand, the film dried without adding a dryer dissolved after 48 hours. Example 2 Instead of the maleic acid half ester of dehydrated castor oil fatty acid diglyceride in Example 1, itaconic acid half was prepared from hydroxyethyl linseed oil fatty acid amide obtained by the reaction of linseed oil fatty acid and monoethanolamine and itaconic anhydride. The emulsion polymer obtained by polymerizing in the same manner as in Example 1 except that 20 parts of ester was used was a highly stable emulsion of fine particles. The coating film curability of the emulsion showed excellent solvent resistance similar to the coating film obtained in Example 1. Example 3 Aminoethyl dehydrated castor oil fatty acid amide was produced from dehydrated castor oil fatty acid and ethylenediamine,
Next, a 10% aqueous solution of 25 parts of maleic acid half amide obtained by the reaction of this fatty acid amide and maleic anhydride neutralized with potassium hydroxide, 35 parts of methyl methacrylate, and 40 parts of butyl acrylate were mixed in Example 1.
Emulsion polymerization was carried out according to the method of . A solvent-resistant film with little swelling was obtained from this emulsion. Example 4 10% of 25 parts of half ester obtained from 1 mole of dehydrated castor oil fatty acid glycidyl ester prepared from dehydrated castor oil fatty acid and epichlorohydrin and 1 mole of citraconic acid, neutralized with triethylamine.
An emulsion obtained by emulsion polymerization of an aqueous solution, 35 parts of methyl methacrylate, 40 parts of butyl acrylate, and 2 parts of acrylic acid according to the method of Example 1 has water resistance,
A film with excellent solvent resistance was obtained. Example 5 3-chloro- produced from sorbic acid and epichlorohydrin in place of the maleic acid half ester of dehydrated castor oil fatty acid diglyceride of Example 1
Emulsion polymerization was carried out in accordance with Example 1, except that 20 parts of pure ammonium salt of a half ester produced by the reaction of 2-hydroxypropyl sorbic acid ester and maleic anhydride was used in the form of a 10% aqueous solution.
A film with excellent solvent resistance was obtained from the emulsion thus obtained. Example 6 Instead of the neutralized half ester of Example 4, 1 mole of the reaction product of 1 mole of dehydrated castor oil fatty acid and 1 mole of hexamethylene diisocyanate and 3-
Emulsion copolymerization was carried out in accordance with Example 4 except for using 25 parts of a pure 10% aqueous solution of an ammonia-neutralized compound having two carboxyl groups prepared from 1 mole of butene-1.2.3-tricarboxylic acid. The emulsion added with a dryer forms a film with excellent water resistance, solvent resistance, and adhesion. Example 7 A 10% aqueous solution of an ammonium salt of maleic acid half-oleylamide obtained from maleic anhydride and oleylamine was prepared using 20 parts of pure content, 40 parts of methyl methacrylate, 40 parts of butyl acrylate, and 4 parts of hydroxyethyl methacrylate. Emulsion polymerization was carried out according to Example 1. As a result, a cold-curable emulsion with excellent mechanical stability was obtained. The test results of the solvent resistance and water resistance of the samples obtained from each of the above examples are displayed.

[Table] Each emulsion obtained in Examples 1 to 7 was applied to a glass plate at a concentration of 20 g/m ² -(Dry), and after being left at room temperature for 48 hours, the test solvent was applied to the dry film for 10 minutes and water was added. Spot the area for 24 hours and check the condition of the film.

Claims (1)

[Claims] 1 (A) (a) a compound containing in one molecule an air-drying unsaturated double bond and a functional group capable of reacting with a carboxyl group or its anhydride group; and (b) an ethylenically unsaturated polybase. 0.5 to 70 parts by weight of a basic salt of a reaction product obtained by reacting a polycarboxylic acid or its anhydride in such a proportion as to leave at least one carboxyl group, and (B) copolymerized with the above component A. A dryer is added to an aqueous dispersion of an acrylic resin obtained by emulsion polymerization of 99.5 to 30 parts by weight of a vinyl monomer whose main component is an acrylic monomer that can be used in an aqueous medium. A room temperature curable aqueous coating composition.