Ink Handling

Conditions to avoid
Some of the chemicals which make up UV and EB inks are reactive and somewhat unstable. In order to make sure energy curable inks work the way they are supposed to, there are two categories of conditions and chemicals that should be avoided: 1) those which induce self curing and 2) those which inhibit normal curing.
 

1. Conditions which induce self curing:
   • Sunlight
   • Fluorescent light after long periods of exposure
   • Fire or flame
   • Extended storage at high temperature (over 95°F)
   • Particles of rust
   • Strong acids, bases or strong oxidizing materials
   • Metal containers
   • High shear pumps
2. Conditions which can prevent ink from normal curing:
   • Excessive oxygen
   • Foreign particles of dust
   • Too thick of an ink layer
   • Old or dirty lamps and dirty reflectors

Materials which are recommended

• Preferably black color, breathable types of polyethylene, polystyrene, polypropylene containers which are phenolic lined
• Stainless steel tools
• Low shear, diaphragm pumps

Altering Ink Viscosity
Energy curable ink is formulated to work well as it comes from the can. However, depending on the job, some alteration of viscosity with reactive diluents may be desirable. Since excessive dilution can slow down the curing rate, no more than 10 parts of thinner per 100 parts of ink should be used

Note: Heat build up in the press must be controlled to prevent viscosity breakdown. With viscosity breakdown, print performance will deteriorate as with conventional printing. Transfer and lay are the traits most affected by heat build-up.

Photoinitiator Addition
Some UV inks are formulated as a multi-part ink system. Instructions for use of these inks will be sent with the inks. These multi-part ink systems have been carefully formulated to give optimum cure speed when the photoinitiator is added at the prescribed rate. More or less photoinitiator can cause dramatic changes in the cure speed.

Mixing/Matching
UV or EB ink colors can be mixed and matched in the same way as conventional inks. Note, however, that UV and EB inks should never be mixed with each other or with conventional inks.

Disposal
As with conventional inks, UV and EB inks should not be poured in the sewage system or anywhere else that would allow it to seep into the water table. Some components of energy curable inks will decompose slowly and will, therefore, remain active in the environment. Inks can be disposed of in two ways:  

• Allow the inks to cure before discarding;
• Have the inks disposed of by a chemical incineration plant or approved chemical landfill.

Freezing
Although UV/EB inks can be frozen, freezing should be avoided whenever possible. If an ink is frozen, DO NOT thaw it with an immersible heater or a belt or band heater. Uneven heating of the ink will cause rapid self-polymerization.

The only way to thaw UV/EB ink is slowly! Either completely immerse the ink container in a warm water bath (under 95°F) for not less than 24 hours or let it sit at room temperature until the ink is completely thawed.

Shelf Life
Minimum UV/EB ink shelf life in a closed container is up to 6 months.

When left alone in a dark, closed container, UV ink will slowly react with itself. When this reaction first starts, a gel will begin forming in the bottom of the container.

Crushing gelled ink is not recommended. Once it has cured, it cannot be crushed and cured again.

The only way to extend the shelf life of an ink is to store it in a cool area in a non-metallic container and keep a good blanket of air in the storage container. Oxygen helps slow the self-curing reaction.