Curing Process

There are a number of control variables in the curing process. These include time-intensity profiles, spectral ranges, the positioning of the piece being cured to the delivery method of the UV light. All variables are related to the characteristics of the piece being cured and the adhesive.

UV light curing adhesives employ a photoinitiator (PI) to trigger the hardening of the adhesive. When sufficient light of the correct wavelength range is absorbed by the PI, it will begin the curing reaction.

When the reaction is complete, the cross linking process has transformed the liquid adhesive into a solid plastic. The physical properties of the finished plastic are critical to the manufacturing process

How UV Curing Works

Materials that require UV light for curing provide a cure-on-demand capability. Most materials require compounds to harden via temperature or a mixture to be used within a certain time frame to achieve the desired results. There is no mixing requirement for UV-cured materials, nor is there any requirement to dispense the material within a certain time frame resulting in the elimination of mixing processes, manufacturing processes and manufacturing time.

In its most basic form, UV curing involves a photo-chemical reaction which converts a liquid or semi-liquid compound to a hard plastic-like polymer. The heart of this reaction is a special compound, known as a "photoinitiator", which absorbs light and then uses the absorbed light energy to initiate and propagate the curing reaction. Unlike conventional drying processes which use heat to evaporate water or solvents from a material, UV curing involves a total conversion of liquid material to a solid state. This lack of solvents makes UV curing an attractive alternative in cases where solvent emissions must be reduced. The hard plastic-like cured polymer usually has superior physical properties (such as abrasion-resistance, gloss, and chemical resistance). These properties are used effectively in many printing and industrial applications. The UV curing process is very fast, usually completed in fractions of a second. This means reduced space requirements and an increase in production. Associated secondary drying operations are eliminated with UV curing and in many cases, quality of the end product can be greatly improved. Both the light source and the UV curable material are normally designed for each specific application.