JPS58193193A - How to repair deteriorated printing film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for repairing deteriorated printed coatings printed on plastic containers.

Plastic containers currently used in many areas, such as those used for transporting and storing beer, carbonated drinks, milk bottles, etc., are made of polyolefin resins such as polyethylene or polypropylene. In the market, they are collected and used repeatedly. The lifespan of these plastic containers is 2
, it is expected that it will last more than 0 years.

Further, these plastic containers are usually printed with the company name, product name, etc. of each manufacturer, and epoxy or urethane silk screen ink is used for printing.

Plasti, which is used repeatedly over a long period of time,
Containers are often stored outdoors, and as the surface is exposed to sunlight and wind and rain, the printed coating deteriorates significantly. In particular, printed coatings printed using epoxy resin inks that have been used for more than 1,000 years are susceptible to chalking. In other words, the current situation is that the appearance is impaired due to reduced gloss, fading, and powdering of the printed film, and at the same time, the powdered printed film contaminates the clothing of the handler, reducing the product value.

Conventionally, the method of repairing such chalking was to paint the surface of the plastic container and form a transparent film on both the container base surface and the printed coating surface, but the main material of plastic containers Polyolefin resins such as polyethylene or polyglopylene have extremely poor adhesion, and therefore have the disadvantage that the coating coated thereon is easily peeled off.

In view of the above-mentioned drawbacks, the present inventors have conducted various studies on methods of selectively forming a film only on the printed film surface without forming a film on the polyolefin resin base surface, which is difficult to adhere to. The surface tension of the resin is 31 dyne/cm for polyethylene and 23 dyne/cm for polypropylene, while the surface tension of the epoxy resin used in printing ink is 50 dyne/cm.
The present invention was achieved by paying attention to the relatively large size of 7 cm 2 and by applying the principle that a liquid having a surface tension greater than that of a solid is difficult to wet the surface of the solid. That is, the present invention is characterized in that the step (A) of coating or dipping the partially printed polyolefin resin container surface with a water-based paint is sequentially applied to the unprinted surface to make it water-repellent. This is a method for repairing deteriorated printed coatings.

The water-based paint of the present invention is prepared by adding 1% to water or a water-containing solvent.
A water-dispersible resin dispersed in a range of ~40% by weight,
Or a water-soluble resin dissolved in the range of 1 to 20% by weight, which can be diluted with water and has a concentration of 40 dyne.
/crn or more.

As the water-dispersible resin, for example, acrylic resin,
Examples include vinyl acetate resin, urethane resin, epoxy resin, and polyester resin.

Examples of water-soluble resins include acrylic resins, polyester resins, and epoxy resins.

Even if water-dispersible or water-soluble hardening agents, such as melamine resins, urea resins, and epoxy resins are added to the above-mentioned water-dispersible resins and water-bathable resins, or those that are partially crosslinked with these hardening agents and rented. good.

Organic solvents used in water-containing solvents include alcohol solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and butyl alcohol, and ether solvents such as cellosolve, butyl cellosolve, and calpitol.

Additives such as antifoaming agents and antifungal agents used in ordinary water-based paints can be used in the water-based paint of the present invention as long as the surface tension of the paint can be maintained.

The present invention utilizes the fact that the surface tension of the water-based paint is higher than that of the base surface of a plastic container to selectively paint only the surface of the printed film. However, the difference is extremely small compared to that of the base surface of the plastic container, so the wet state of the water-based paint on the printed coating surface is maintained sufficiently.

In the present invention, specific methods for coating the container surface with the water-based paint include a method using a through-coating machine, a flow coating method, a roll coating method, a coating method using a spatula, etc. Alternatively, the sides of the container including the printed surface or the entire container may be immersed in the water-based paint.

7. In order to remove the water-repellent water-based paint from the surface of the printed container in the present invention, it is easy to maintain the application surface vertically, and the water-repellent water-based paint can be removed without deforming the plastic container when it falls. Alternatively, hot air may be blown onto the printed surface.

According to the present invention, the faded and chalked printing film of the reglastic container is covered with a transparent film to restore the original color tone and gloss of the printing, and the plastic container can be used continuously without fading due to friction. It becomes possible.

Examples of the present invention will be described below. The amounts (parts) described in each example represent parts by weight.

Example 1 Water-dispersed epoxy resin 10 parts Butyl cellosolve 2 parts Water 88 parts Water-dispersed epoxy resin was Aloron 5 manufactured by Nippon Shokubai Kagaku #, and a coating material was prepared according to the above mixing ratio. A plastic container made of resin, mainly made of polyethylene, whose printed film has deteriorated and is chalked, is immersed in this paint solution until the printed surface is submerged in the paint solution, then pulled out, and the entire plastic container is air-filled. I blew it to remove excess paint and let it dry at room temperature.

The gloss of the printed coating surface of the plastic container thus repaired was measured as a specular reflectance at 60° C. and found to be 30.5. The reflectance of the surface of the unrepaired printed film measured in the same manner was 11.3. The color tone of the repaired printed film was also improved compared to before repair, and no color fading due to friction was observed.

Example 2 Water-soluble acrylic resin 5 parts Isopropyl alcohol 2 Water 93 The water-soluble acrylic resin was Alloron 55 manufactured by Nippon Shokubai Kagaku ■.
Using 7N, the paint was adjusted to have the above blending ratio. In this paint solution, apply the above paint solution only to the printed side of a plastic container made of resin mainly made of polyethylene, whose printed film has deteriorated and is chalked, using the 70-coat method. The painted surface was air-blown to remove excess paint and then dried at room temperature.

The surface gloss of the printed coating on the plastic container thus repaired was measured as a 600 specular reflectance and found to be 39.3. The reflectance of the surface of the unrepaired printed film measured in the same manner was 11.0. The color tone of the repaired printed film was also improved compared to before repair, and no color fading due to friction was observed.

Patent applicant: Toyo Ink Manufacturing Co., Ltd.

Claims (1)

[Claims] (1) Step of coating or dipping the partially printed polyolefin resin container surface with a water-based paint (8) Removing the water-repellent water-based paint from the unprinted surface. A method of repairing a deteriorated printing film.