UV energy curing inks, coatings and varnishes provide the printer with many advantages and benefits over so called conventional products. These conventional products may be solvent or aqueous types in the case of flexo and gravure or oxidizing types in the case of litho or letterpress or a variety of types in the case of screen printing.
UV energy curing products benefits:
- No solvent emissions, zero VOC, no fire hazard, and no hazardous solvents
- Designated “Best Available Control Technology” by EPA
- 100% solids applied = an ability to achieve greater densities
- Exceptional color strength/consistency
- High transparency
- Superior gloss & retention
- Minimal dot gain and color bleed = exceptional image sharpness
- No consistency change due to solvent evaporation or Ph influence
- Inks maintain consistency throughout a press run
- UV inks, coatings and varnishes do not dry or plug anilox cells
- No need to clean up between press runs
- No need to clean up over a weekend shutdown
- Reduced down time, waste and clean-up
- Instant curing, increased productivity, inline processing, and just-in-time delivery
- Excellent abrasion, chemical, and product resistance
- Low odor
- Adhesion to a wide range of materials
- Energy savings
- No set-off
- Eliminates offset spray powder
- Faster make-readies
- Range of special effects coatings
UV inks, coatings and varnishes are in use currently in virtually every printing process including sheetfed, and web offset, flexo, gravure, letterpress, screen, and inkjet. Offset inks are run routinely dry trapping, but also may be run wet trapping. Dry wrapping is accomplished using inter-station curing after each print unit. Wet trapping can be done with two or more inks using a trailing UV curing unit or units.
UV top coatings & varnishes may be effectively applied over inks to provide stellar gloss, or unique other finishes either in-line or off-line.
UV top coatings can provide a high gloss level that is second to none, and are therefore the choice when high gloss coupled with protection is desired.
Foil stamping, as we know, is a decorative product technology that is broadly used to enhance the appearance of graphic arts products. A broad range of rich brilliant reflective, consumer attracting, effects can be obtained. These include bright gold’s, and silvers, satins, mattes, metallized, and opaque colors, tints, pearls, and holographics. Extremely successful applications may be found on a vast variety of consumer products, including, greeting cards, book covers, labels, annual reports, clothing, and cosmetic, liquor, and cereal packaging, etc.
Hot foil stamping application methods involve the use of an engraved die, and a heated press to transfer foil from a thin carrier.
Stamping foil construction consists of:
- Clear Polyester Film (PET) carrier
- Release coat
- Color coat
- Adhesive coat
An alternate and newer “Cold foil transfer” process is growing in use due to its ability to improve productivity. This process aimed at supporting in-line processing involves the use of an adhesive print station to selectively water base adhesive coat a substrate. The adhesive is applied in registration with printing, and is dried prior to being brought into contact with a web of foil under pressure to affect foil transfer. Nip roll pressure effectively bonds the decorative foil to the substrate.
Generally, it is conceded that it is better to UV top coat over foil stamping as opposed to stamping onto a UV coated surface. This position is taken because it eliminates the question of obtaining adhesion to a UV coating. Foil suppliers of necessity must supply a range of adhesives on their foil products in order to obtain adequate adhesion to a range of different substrates. However, in any case the key to foil stamping success is the dyne level of the surface to which one is foil stamping. A substrate dyne level of 38 dyne/cm or higher is required in order to achieve acceptable foil stamping transfer, and adhesion.
UV high gloss coatings are also available that are specifically formulated to provide a cured film dyne level of 38 dyne/cm or higher. This makes them capable of accepting designated hot stamping foils. These specific foils are those that receive a foil supplier application of select adhesives so that adequate adhesion to "stampable” UV and aqueous coatings may be expected.
It is well to not forget that the success of a hot foil stamping application/adhesion process remains very much dependent on correct stamping temperature, pressure, and dwell time, even if the substrate dyne level is 38 dyne/cm or even higher.
Hot foil stamping over UV energy cured inks is common, but one must be aware of the fact that success is dependent on the inks being adequately cured, as well as having the proper dyne level.
UV inks are also a good choice when contemplating the over printing of stamped foil decoration. The big factor is that the instant curing of UV inks eliminates the drying time factor of oxidizing conventional inks. The instant UV in-line curing of UV inks further eliminates the possibility of waste product due to smearing or set-off, while improving over all productivity.
LOOK TO CORK! Our business at Cork Industries is the development and formulation of aqueous, energy curing Ultraviolet (UV), and Electron Beam (EB) specialty coatings, and adhesives. Cork thrives on its ability to formulate novel, useful specialty products that offer the graphic arts industry printer/coater a competitive advantage.