Quality control of prepress for pad printing of th

Quality control of pretreatment of polyethylene bottle pad printing

printing polyethylene and polystyrene plastic surfaces with pad printing machine can be printed directly, just like silk printing. However, corona and flame treatment must be carried out before pad printing, otherwise, the printed pictures and texts are easy to be erased, and the printing quality cannot meet the requirements, so the quality of prepress treatment must be controlled

I. surface treatment

1 High frequency discharge treatment. Apply high-voltage (2 ~ 100kV) and high-frequency (2 ~ 20kHz) electricity to the electrode, generate corona discharge between the two poles, generate a large amount of plasma gas, when the cross-sectional size is greater than 35 mm, and ozone, directly or indirectly interact with the molecules on the surface of the plastic bottle, so that the molecular chain on the surface of the plastic is introduced into polar groups, so as to achieve the purpose of surface treatment

2. Flame treatment. Use flame processor to carry out flame combustion treatment on the surface of the bottle to oxidize its surface and increase surface tension. The specific methods are as follows: (1) the proportion of air and gas is 5% - 15%, so that the gas is in the most economical use state. 6. If the fatigue testing machine is completely burned during the process of experimental detection. (2) The distance between the flame tip and the bottle surface is 10 ~ 15mm, that is, the outer flame at the highest flame heat, which is the best oxidation effect. (3) The exact contact time between the flame and the phenolic foam prepared by heating the bottle can be determined by repeated tests. Start the machine first and process several samples. If the sample surface shows no signs of oxidation treatment or is not very hot, the contact time is too short. On the contrary, if the bottle is deformed, it means that the time is too long and the contact time needs to be shortened

II. Identification of treatment effect

1 Submerged inspection method. Soak or rinse the treated bottle with water for more than 3 seconds, take it out, observe and calculate the retention time of the whole plate of continuous water film on the surface of the bottle. If it is within 4 ~ 9 seconds, it indicates that it has hydrophilicity. If it is lower than this number, it indicates that the effect of oxidation treatment is poor; If it takes more than 12 seconds, the ink can adhere to the plastic surface well. The most suitable treatment degree is that the water film can remain until the water evaporates completely

2. Surface tension test method. Mix ethylene glycol ether and formamide in a certain proportion to prepare a 40 dyne/cm surface tension test solution, dip the test solution with a cotton swab, and apply a certain area on the surface of the treated bottle. If the liquid film remains unbroken for more than 2 seconds, it means that the treatment requirements are met; Otherwise, the surface tension of the bottle does not meet the standard

conclusion

the digital plate making method was applied to transcribe printing, which gave birth to the digital hole printing machine and created the basic conditions for the production of plate making and printing integrated machine. In the future, the requirements of digital hole printing machine for oil cleanliness will be lower than that of electrohydraulic servo valve. As a high-speed printer connected with network, it will be paid attention to. As a high-speed image output device to cope with the information society, it is expected to have further development

Ricoh develops digital hole plate technology based on the hole plate technology of simple plate making method according to the requirements of customers, making it a printing machine with clearer graphics and texts, simpler operation, higher reliability, better environmental adaptability and cheaper. As safety production and environmental protection will be paid more and more attention, the characteristics of low energy consumption (power saving) and pollution-free ink (environmental protection) of digital hole printing machine without high-temperature fixing are meeting the modern trend, and new technology development is being carried out towards enriching peripheral devices, expanding printable paper types, and improving operating performance

source: liuzhihua, Wanan emerging silk screen printing technology center of printing technology