The printing of PET is very different from the printing and processing technology of paper materials. In processing, attention must be paid to five issues such as material properties, surface pretreatment, and printing methods. Because PET material occupies an important position in variable information printing, it belongs to film printing, which is very different from paper materials in printing processing technology. The following are some key points of PET film printing summarized by Xiaobian, let's take a look.
Material properties
PET film is a plastic film material with medium and low surface energy. It needs surface pretreatment before printing to improve the surface removal energy or wetting ability. Otherwise, the ink and ribbon have poor firmness and are easy to fall off.
Basic methods of surface pretreatment.
a. Corona treatment. The surface energy of the material is increased by means of high voltage discharge. There are two methods of pre-processing at the time of making the material by the supplier and in-line processing on the press. The surface tension of the treated film is required to be above 38dyn. It should be noted. No matter how much current corona is used for some PET materials, the surface tension value cannot be increased, so there are not many manufacturers who use the corona method for surface treatment.
b. Surface coating. The surface of the material is pre-coated with an affinity ink coating, such as corona-free PET film surface treatment agent and PET film surface treatment agent, to improve its wetting ability to ink and increase the firmness of ink. This processing method is the most ideal, most common and most stable method for PET materials.
printing method
a. Printing lamination method. Use Xitong offset printing to draw ink, die-cut with matt PET or BOPP film immediately after printing, and there is no problem of ink drying. This type of processing does not require any surface properties of the material, and the matte surface of PET or BOPP can be printed with ribbons. This method is a commonly used method. However, the cost is high, and the label bending phenomenon is prone to occur after the large label is laminated.
b. Printing varnishing method. Inline printing and UV varnishing on a web labelling machine using UV inks. The glazing process can use the whole glazing or partial glazing to reserve the printing part. This method is also a method commonly used by customers.
c. UV printing method. Printed with UV ink. No lamination or glazing is required, and the printing area is reserved.
d. Printing drying method. Using special oxidative polymerization type quick-drying special ink, after printing, it is dried by hot air drying tunnel, and finally rewound.
e. Natural in drying method. This type of label is usually used for manual labeling, so the processing method adopts the method of roll printing and then cutting. After printing, the labels should be put on the shelf after being cut to dry naturally. Similarly, the ink used is a special oxidative polymerization type fast-drying special ink.
quality assurance
a. The surface of the material must be pretreated and meet the standard.
b. Use the matching special ink, varnish and ribbon, which should be tested in advance.
c. Control the thickness of the ink layer and dry it thoroughly. Pay attention to the overprinted part of the ink to prevent the lower layer of the ink from drying out.
Die cutting
a. Use a die-cutting blade with a small angle, a 42-degree angle is recommended.
b. Use hard die-cutting blade of alloy material.
c. Maintain the sharpness of the blade.
d. Be careful not to use the die-cutting knife that has cut through the paper to die-cut the film material again.
e. Use hard pads, pay attention to flatness, otherwise die-cutting quality problems will easily occur.
The above are some points of PET film printing, I hope to help you, if you need high-quality PET film, you can contact us at any time!
