UV printing ink curing principle
Uv printer USES uv special ink. Unlike regular ink, uv ink usually solidifies in a very short time after printing, presenting solid state. Uv ink is divided into several stages from liquid to solid. This paper will briefly explain this.
1. What is the principle of uv curing?
Uv curing is to point to in under the irradiation of ultraviolet light, light initiator absorbs ultraviolet radiation energy divided into free radicals and react. In a very short period of time curing reticulate polymer. Therefore, uv coatings, inks and adhesives are converted from liquid to solid in seconds, forming a hardening film.
The uv curing process can be divided into the following five stages.
(1) Photoinitiator absorbs uv light and becomes the photoinitiator of excited state.
(2) The excited photoinitiator is unstable and is easily decomposed to form free radicals.
(3) The interaction of unsaturated groups in free radicals and prepolymers can result in addition, crosslinking, or polymerization reactions, forming free radical intermediates.
(4) Free radical intermediates can be rereacted by chain growth, and get a long chain or a network of polymer free radical intermediates.
(5) Long chain or reticular polymer free radical intermediates produce chain termination reactions, and the original liquid components are converted into solid polymers.
2. What are the influencing factors of uv curing?
The main factors affecting uv curing reaction are: uv curing equipment of the emission spectrum and the radiation intensity of uv lamp, uv printing ink, paint, or in the light of the initiator of the absorption spectrum and its formula.
In the uv curing reaction, the most important thing is to determine whether the emission spectrum of uv lamp tube in uv curing equipment matches the absorption spectrum of uv ink, paint or adhesives. If the two do not match, then the photoinitiator cannot be stimulated and the uv curing reaction cannot be completed successfully. If the two do not match perfectly, it is easy to cause the uv curing reaction not completely; If the two match, the curing effect is directly related to the radiation intensity of uv light source. In addition to the matching problem of the spectrum, in the curing reaction of uv curing equipment, selection of uv ink, coating and adhesive also should give attention to both surface and deep solidifying effect, to meet the requirements of different applications.