Post-treatment after the screen printing

Post-treatment after the screen printing process
The main purpose for treating components after the printing process is to reduce the curing time. Post-treatment, or curing, is usually used in applications where the components will undergo additional processing within a relatively short time. Post treatment increases the rate of polymerization of many polymers including polypropylene, polyethylene and poly vinyl chloride.

Folowing are the post-treatment techniques generally used in the printing industries

Oven curing
Generally oven curing is used to cure printing inks/paints on substrate like metals, glass and some plastics. For plastics, oven curing helps in polymerization. Polymerization is a process of formation of complex polymer chains from monomers.

Polymerization occurs in polymers like polyethylene, polypropylene and poly vinyl chloride etc. Oven curing imparts high strength bonds between monomers and also encourages it to grow in high temperature environments.

Hot air gun treatment
Hot air gun is used to post-treat of material by blowing a hot air stream of approximately high temperature for 2-3 seconds as per requirements, just after the printing.

Infrared dryer
Infrared dryer consists of IR lamps and air blades. The IR radiation is electromagnetic wave that lies above the visible range in the spectrum. IR dryer has high end infrared radiators as heating source and have various advantages over other dryer such as high efficiency, low response time, uniform heating tendency, low energy consumption, green technology and have very compact design.

The air blades are used to distribute the heat uniformly on the substrate for quick curing of inks. The lamps power can be optimized as per the requirement on specific substrate.

U.V dryer
The UV dryer uses UV lamps as heat energy source. The UV radiation lies in the visible range of spectrum in the wavelengths of 200 to 480 nm. UV energy has tendency to cure inks/paints/coatings in very short span of time i.e. within fraction of a second.

The main components of UV dryer include: UV lamps, reflectors, lamp housings, a cooling system and electronic control system. UV dryer is generally used in rotary screen-printing or where very fast drying system is required.

Selection of the best-suited Pre/Post-treatment method will depend upon the chemical composition of the inks/paints/coatings, surface dyne level and other factors.