JPH1095866A - Method for printing plastic molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for printing a plastic molding such as a tubular container having a surface made from a polyolefin, which comprises subjecting only the printing part of the molding to corona discharge treatment and by which it is made printable by an ink jet printing system and the blocking between the surfaces of containers can be prevented. SOLUTION: By way of example, a tubular plastic molding container prepared by forming a laminate sheet the external surface of which is made of a polyethylene resin layer is packed with viscous contents (e.g. butter) and its surface except the printing area is masked and subjected to corona discharge treatment at a treatment speed of 36-40dyn/cm. The treated container is transferred to a printing section to print a shelf life or the like on it, and then end-sealed to accomplish the packing work of an article. According to this process, ink jet printing is made possible even for polyolefin resin surfaces, and blocking between the contact surfaces which occurs if corona discharge treatment is applied to the entire surface can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for printing a plastic molded article, and more particularly to a method for printing on the surface of a plastic molded article having a polyolefin resin as an outermost layer.

[0002]

2. Description of the Related Art The surface of plastic molded articles such as plastic tubes and plastic bottles generally has high liquid repellency and has poor surface wettability with printing ink and the like. To solve this problem, for example,
Surface treatment methods such as corona discharge treatment and flame treatment have been performed, and some effects have been obtained.

[0003]

However, in a surface treatment method such as a corona discharge treatment or a flame treatment, when the surface treatment method is applied to the entire surface of a plastic molded body, the molded bodies overlap each other for a long time, and the contact state of the surface is reduced. When the contact surfaces continue for a relatively long time, the contact surfaces may adhere to each other, that is, a blocking phenomenon may occur. In that case,
When the adhered plastic molded body is peeled off, for example, the printed layer applied to the surface of the molded body is peeled off from the plastic surface and transferred to the molded body on the other side, and the printed layer is destroyed, and the surface of the molded body becomes dirty and rolled. In some cases, problems such as a decrease in commercial value may occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems relating to the surface treatment method for a plastic molded article. By performing corona discharge treatment only on a necessary portion, a contact state can be maintained for a long time. Another object of the present invention is to provide a method for printing a plastic molded article which does not cause a blocking phenomenon.

[0005]

Means for Solving the Problems A first invention of the present invention is:
A printing method for a plastic molded body, characterized in that a corona discharge treatment is applied to a printed portion on the outer surface of the plastic molded body, and the printed portion is printed by an ink jet method.

A second invention is the method for printing a plastic molded article according to the first invention, wherein an outer surface of the plastic molded article is a polyolefin resin.

[0007] As described above, according to the present invention, since the corona discharge treatment is partially applied to the outer surface of the plastic molded body, the blocking phenomenon does not occur even if the contact state between the plastic molded bodies continues.

[0008]

The present invention will be described in detail with reference to the following examples. <Example 1> First, a laminated material having an outer surface made of a polyethylene resin layer was cut into a predetermined size, rounded into a cylindrical shape, and a side seal 11 was produced to produce a body 10, and a synthetic resin neck was formed on the upper end of the body. A neck-shaped plastic molded body having an opening on one side was produced by heat-sealing a neck member 12 composed of a neck and a shoulder, and a cap 20 was attached to the neck to produce a plastic molded body 1 of the present example.

Then, the plastic molded body is set on a filling sealing machine with the side of the plastic molded body fitted with the cap down (inverted state), and a predetermined amount of viscous contents (from the opening in the first filling section). This time, butter) was filled.

In the next corona discharge section, the plastic molded body filled with butter is masked with a masking material around a band-shaped print portion 13 provided in parallel with the cut surface of the opening around the upper end on the opening side. Then, only the printing portion 13 was subjected to corona discharge treatment so that the treatment degree was 36 to 40 dyne / cm.

The plastic molded body having the printed portion subjected to the corona discharge treatment was moved to the next printing section, and a date such as the expiration date was printed on the above-mentioned printed portion by an ink jet method.

The printed plastic molded body was moved to the next sealing section, the upper end of the printed portion was sealed with an end seal 14, and a series of filling operations was completed.

<Comparative Example 1> A butter-filled plastic molded body was produced using the same material as in Example 1 under the same working conditions except that the printed portion was not subjected to corona discharge treatment. (The degree of surface treatment when the corona discharge treatment was not performed was 33 to 34 dyne / cm).

In order to evaluate the adhesion between the ink at the printing portion and the plastic surface of the two types of plastic molded articles thus produced, the same butter as the filler was adhered to the printing portion and rubbed. In the plastic molded article of Example 1, the ink adhered to the surface even after rubbing 50 times, and the ink was not removed. On the other hand, in the plastic molded article of Comparative Example 1, the ink was peeled off from the plastic surface after rubbing 2 to 3 times. It was impossible to identify the date.

[0015]

As described above, when the corona discharge treatment is applied only to the printed portion on the outer surface of the plastic molded body, printing can be performed by the ink jet method, and the blocking phenomenon does not occur.

[Brief description of the drawings]

FIG. 1 is an explanatory view in which a part of a plastic molded body used in the present invention is cut away.

[Explanation of symbols]

 1 Plastic molded body 10 Body part 11 Side seal 12 Neck member 13 Printed part 14 End seal 20 Cap

Claims (2)

[Claims] 1. A printing method for a plastic molded body, comprising: performing a corona discharge treatment on a printed portion on the outer surface of the plastic molded body; and printing the printed portion by an ink jet method. 2. The method according to claim 1, wherein the outer surface of the plastic molded body is a polyolefin resin.