JPH0711185A - Water-based coating composition - Google Patents

Abstract

PURPOSE:To obtain a coating material which does not suffer from problems arising from the use of an organic solvent and can give a coating film excellent in scratch and wear resistances and surface smoothness. CONSTITUTION:This coating composition contains 0.5-10.0wt.%, based on the total weight of the water-based varnish resin, polyethylene oxide. This composition can form a coating film improved in wear and scratch resistances without detriment to the other film properties. The dispersion stability of the wax in the water-based coating material is also very good. This composition has many industrial excellent effects such as improved resistance to scratching and damaging during producing and transporting drink cans, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a varnish resin having a total weight of 0.
The present invention relates to an aqueous coating composition containing 5 to 10% by weight of polyethylene oxide and having particularly excellent effects on abrasion resistance, scratch resistance, and surface lubricity of a coated object.

[0002]

2. Description of the Related Art Conventionally, the outer surface of beverage cans, food cans, caps, crown stoppers and the like has been coated with a coating film for the purpose of protecting its material and imparting color, luster and aesthetics. Furthermore, the coating film is required to have resistance to damage such as beverage cans and abrasion during transportation. In addition, slipperiness during line movement is also required when manufacturing beverage cans and the like. Therefore, these requirements are met by adding a wax silicone or the like to the paint to lower the dynamic friction coefficient of the object to be coated. Usually, in order to reduce the dynamic friction coefficient of the coating film, it is used by adding it to the coating material such as beeswax, spermaceti wax, beef tallow, carnauba wax, lanolin wax, and other animal or vegetable lubricants, or synthetic wax such as polyethylene wax. Alternatively, organopolysiloxane or the like is used.

Further, in Japanese Patent Publication No. 60-17463, polyethylene resin powder or oxidized polyethylene resin powder or a mixture thereof is contained in the varnish in an amount of 5 to 15% by weight based on the total amount of the varnish resin. A crown cap characterized by being coated is disclosed. However, the above-mentioned amount of polyethylene oxide causes cloudiness on the surface of the article to be coated and impairs the aesthetics of a beverage can or the like. The above-mentioned paints are mainly composed of an organic solvent as a solvent, and various aqueous paints have been studied due to recent environmental problems.

[0004]

SUMMARY OF THE INVENTION The present invention solves the drawbacks of paints for coating the surface of beverage cans and the like. In other words, it is an object of the present invention to provide a coating material which does not have the problems associated with organic solvents and whose coating film has excellent scratch resistance, abrasion resistance and surface lubricity. The present invention reduces the dynamic friction coefficient of the surface of a beverage can, which is the article to be coated, by adding an oxidized polyethylene resin powder or an emulsion of oxidized polyethylene to the water-based coating, and the surface smoothness and scratch resistance. It was completed based on the finding that the abrasion resistance is remarkably improved, and is characterized in that the coating contains an oxidized polyethylene resin powder or an emulsion of oxidized polyethylene.

[0005]

The first invention is an aqueous coating composition containing oxidized polyethylene in an amount of 0.5 to 10% by weight based on the total weight of the varnish resin. The second invention is the aqueous coating composition of the first invention, wherein the oxidized polyethylene is an emulsion. Oxidized polyethylene has a particle size of 5 to 20 μ, a molecular weight of 1000 to 4000, and a melting point of 10.
Those having 0 to 120 ° C. are preferable. The content of polyethylene oxide added to the paint is preferably 10% by weight or less, and more preferably 0.5 to 10% by weight based on the weight of the resin. If this content is less than 0.5% by weight, a sufficient reduction in the dynamic friction coefficient cannot be expected, and if it exceeds 10% by weight, the surface of the dried coating film becomes cloudy and the appearance of the article to be coated is significantly impaired. Not preferable.

[0006] In some cases, it is difficult to uniformly disperse the oxidized polyethylene in the water-based paint as it is in the form of powder. Therefore, the water-based paint can be prepared by adding an emulsion of the oxidized polyethylene to water or a mixture of water and a solvent in advance. It stabilizes in and makes it difficult to separate or aggregate. As the base resin, conventionally known acrylic resin, benzoguanamine resin, melamine resin, polyester resin, phenol resin, vinyl resin,
Epoxy resin, alkyd resin, etc. can be widely used.

[0007]

EXAMPLES Next, the present invention will be described in more detail by way of examples. In the examples, "part" means "part by weight" and "%" means "% by weight". Production Example 1 Production of Aqueous Acrylic Resin Solution A1 Butyl Cellosolve 100 was placed in a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, a dropping tank, and a nitrogen gas blowing tube.
While maintaining the temperature at 105 ° C with stirring while introducing nitrogen gas, from the dropping tank, 30% of styrene, 30% of ethyl acrylate, 30% of butyl acrylate, 10% of 2 hydroxyethyl acrylate, 10% of methyl methacrylate, and acrylic. A solution prepared by dissolving 5 parts of benzoyl peroxide in 100 parts of a 10% acid mixture is added dropwise over 3 hours. Then, the reaction was carried out for 1 hour while maintaining the temperature at 105 ° C., 0.5 part of benzoyl peroxide was added, and the reaction was further continued for 1 hour to complete the reaction. Butyl cellosolve was distilled off under reduced pressure at 100 ° C. until the nonvolatile content became 83%, then 14.6 parts of diethanolamine and water were added, and a transparent and viscous water-based acrylic resin having a solid content of 50% and residual butyl cellosolve of 10% was added. A solution (A1) was obtained.

Production Example 2 Aqueous polyester resin solution A2
In a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, a dropping tank and a nitrogen gas blowing tube, phthalic anhydride 12.0
Parts, adipic acid 47.5 parts, ethylene glycol 25.
4 parts were charged and heated to 210 ° C. Cooling was started when the oxidation became 5 or less, 93 parts of ethylene glycol monobutyl ether was added at 170 ° C., and after cooling,
A transparent viscous polyester resin solution (A2) having a solid content of 50% and a hydroxyl value of 45 was obtained. Example 1 Acrylic amino-based paint Aqueous acrylic resin solution A1 ... 80 parts Benzoguanamine resin ... 20 parts were mixed, and oxidized polyethylene wax Mitsui High Wax 4052E (Mitsui Petrochemical Co., Ltd., trade name ) Was added to 10 parts with respect to 100 parts of the resin solid content.
Further, a coating material was prepared by adjusting with water and butyl cellosolve so that the solid content was 30% and the solvent amount was 15%. to this,
An aqueous paint was obtained by adding 0.3% of p-toluenesulfonic acid amine salt and 0.3% of a leveling agent. Example 2 Acrylic amino paint The amount of the oxidized polyethylene wax of Example 1 added was 10
An acrylamino-based paint having the same components as in Example 1 was prepared except that the amount was changed to 0 part to 5 parts.

Example 3 Acrylic amino-based paint An emulsion of the oxidized polyethylene wax of Example 1; trade name Hoechst Wax VN-S244
D solid content 10% (Hoechst Japan) ...
An acrylamino-based coating material having the same components as in Example 1 was prepared except that the content of the thermosetting coating material was set to 10 parts per 100 parts. Example 4 Polyester amino-based paint Aqueous polyester resin solution A2: 80 parts Benzoguanamine resin: 20 parts were mixed and oxidized polyethylene wax Mitsui High Wax 4052E (trade name, manufactured by Mitsui Petrochemical Co., Ltd.) ) Was added so as to be 10 parts with respect to 100 parts of the resin solid content. Furthermore, solid content 30% with water and butyl cellosolve, solvent amount 1
The paint was prepared by adjusting it to be 5%. And p
-Toluenesulfonic acid amine salt 0.3% and a leveling agent 0.3% were added to obtain an aqueous paint.

Example 5 Polyester Amino-based Paint An emulsion of the oxidized polyethylene wax of Example 4; trade name Hoechst Wax VN-S244D
(Manufactured by Hoechst Japan Co., Ltd.) ... An acrylamino-based paint having the same components as in Example 4 was prepared except that the amount of the thermosetting paint was 10 parts per 100 parts of the solid content. Comparative Example 1 Acrylic amino-based paint The addition amount of the oxidized polyethylene wax of Example 1 was 10
An acrylamino-based paint having the same components as in Example 1 was prepared except that 0.2 part was used for 0 part.

Comparative Example 2 Acrylic amino-based paint The amount of the oxidized polyethylene wax of Example 1 was 10
An acrylamino-based coating material having the same components as in Example 1 was prepared except that the content was changed to 0 part to 15 parts. Comparative Example 3 Acrylic Amino-based Paint Instead of the oxidized polyethylene wax of Example 1, melting point 80-84 ° C. Nocarnauba wax; trade name Purified Carnauba Wax NO. 1 (manufactured by Noda Wax) ...
.. An acrylamino-based paint having the same components as in Example 1 was prepared, except that the amount of the thermosetting paint was 10 parts per 100 parts of the solid content.

Comparative Example 4 Acrylic amino-based paint A microcrystalline wax having a melting point of 88 ° C. in place of the oxidized polyethylene wax of Example 1; trade name X-
1005 (manufactured by Gifu Shellac Seisakusho Co., Ltd.) ... An acrylamino-based paint having the same components as in Example 1 was prepared except that the thermosetting paint solid content was changed to 10 parts per 100 parts. Comparative Example 5 Acrylic Amino Paint Acrylic amino paint of the same components as in Example 1 was prepared except that the oxidized polyethylene wax of Example 1 was not added. The thickness of these paints was reduced to 0.
It was applied to a 23 nm electroplated tin plate and baked at 180 ° C. for 10 minutes to cure. The film thickness was 4 to 5 μm.

Table 1 shows the stability and coating film physical properties of the coating materials prepared in Examples and Comparative Examples. Each test method shown in Table 1 is as follows. Paint test ○ Paint stability test After the paint was stored at room temperature for 2 months, the state of separation and aggregation of wax in the paint was observed. ○ Physical property test of coating film A surface-treated aluminum plate having a plate thickness of 0.26 mm is coated with a roll coat to a coating film thickness of 5 µm after drying, and the gas oven is used at an atmospheric temperature of 180 ° C for 10 minutes. A baking panel was created. The scratch resistance was evaluated by preparing a 60 mm cap formed by molding a coated plate so that the coated surface was the outer surface of the cap. ○ Sliding property test It was evaluated by a dynamic friction coefficient by a three-point support method at a load of 1 kg and a pulling speed of 1.5 cm / sec. ○ Scratch resistance test Stainless steel mold is installed on the circumferential surface and height is 2
200φ × 40 with 0m / m scratch plate attached
The cap was attached to the hopper ring tester using a hopper ring tester equipped with a 0 l cage. First, the above-mentioned cap is put into a hopper ring machine and stirred for 30 minutes. Next, this was taken out, and the extent of scratches on the cap surface was visually determined. -Abrasion resistance test The coated plate as described above was evaluated using the Gakushin type fastness test.

A coated plate cut into a size of 10 cm × 10 cm was mounted on a test stand, and a reciprocating motion of 5 cm was repeated, and a 1.5 cm × 1.5 cm wear plate was applied to the coated surface.
The abrasion resistance was evaluated by the number of times that the coating film was pressed and abraded with a load of 0 g to be destroyed by abrasion and the underlayer was exposed. ○ Surface condition of coating film The cloudy cloudiness on the coating film surface of the coated plate was visually observed.

[0015]

[Table 1]

[0016]

As described above, the aqueous coating composition of the present invention has improved abrasion resistance and scratch resistance without impairing other physical properties of the coating film. Also, the dispersion stability of the wax in the water-based paint was very good. As a result, many excellent effects in industry such as improvement in resistance to damage and breakage during manufacturing and transportation of beverage cans are brought about.

Claims (2)

[Claims] 1. A water-based coating composition comprising oxidized polyethylene in an amount of 0.5 to 10.0% by weight based on the total weight of the aqueous varnish resin. 2. The aqueous coating composition according to claim 1, wherein the oxidized polyethylene is an aqueous emulsion.