Cold Foiling growth and productivity improvements have come rapidly. Foiling is known for its ability to add eye-catching visual effects to all aspects of printing creating brand differentiation. Foiling has proven to be effective in attracting and persuading shoppers to choose one product over another.
First developed in the 1990’s for the rotary narrow web printing industry, cold foiling evolved from hot foil stamping. The objective was to deliver a fast, in-line, cost-effective option to hot foil stamping. Now mature, the technology has been adapted by most printing processes including flexo, sheet, and web-fed offset, and digital.
Foiling, achieved by cold foiling or hot stamping, is a decorative metallic technique used to enhance graphics. A broad range of eye-popping rich, brilliant, metallic/color, consumer attractive effects can be produced.
Cold foiling is the process of using a UV curable adhesive to transfer easy release metallic foils to a variety of substrates. Cold foil has a similar structure to hot foil consisting of layers of material differing, with a release coating reacting to shear instead of heat. The adhesive coating is formulated to have an affinity for a UV adhesive printed onto a substrate.
COLD FOIL CONSTRUCTION
- Polyester film carrier
- Release coating
- Color coating
- Adhesive affinity coating
There are two forms of cold foil printing:
- Wet lamination (UV cure-through foil)
- Dry lamination (conventional UV tack)
WET LAMINATION PROCESS
In this process, a specially formulated UV curable adhesive is printed onto a web substrate using a standard in-expensive photopolymer plate. Next, a cold foil film web is nip laminated onto the wet adhesive. The UV adhesive is then cured through the metalized foil, creating a foiled image. This is followed by the spent carrier film being stripped away and rewound with the cold foil image remaining on the substrate. Critically, the metalized cold foil layer must allow UV curing energy to pass through it to cure the UV adhesive creating a bond. Cold foil, after application, is a very thin two microns thick.
DRY LAMINATION PROCESS
Similar to the wet lamination process, a specially formulated UV curable adhesive is printed onto a web substrate using a standard photopolymer plate. The UV adhesive is then cured leaving the adhesive in a “tacky” state. The cold foil film web is then laminated to the tacky adhesive using a high-pressure nip. This action effectively transfers the metalized foil onto the adhesive coated substrates image. The remaining spent carrier film is then stripped away and rewound leaving a cold foil image on the substrate.
The chemistry key to the cold foil process differs from that of hot foil stamping, in that it is dependent on a peel-off technique and not heat. Therefore, heat-sensitive substrates, such as flexible packaging films, plastic laminate tubing, shrink sleeves, and other thermally sensitive stocks can be accommodated.
Cold foiling excels in handling large coverage areas, fine lines, gradients, halftones, overprinting and top coating, with the ability to offer multi-colored creative effects.
Hot stamping, in contrast, uses heat and pressure to activate release and adhesive coatings in order to laminate an image to a substrate. This limits its use to non-heat sensitive substrates. The process uses an expensive engraved brass die, unique to a job, and a heated press. It is a slow process, used mostly off-line over preprinted graphics and is limited to text, and bold mirror-like images.
Cold foiling needs smooth surface substrates in order to produce the best image results with films, coated papers and boards all in high-volume use. Generally, all films (PE, PP, PET, PVC), perform ideally since they are non-porous and do not allow absorption of the UV adhesive.
Many OEM press manufacturers now make available cold foil units, either as a fully integrated unit or as an optional add on unit. The cold foiling market demand is now being met by new presses set-up to apply cold foiling and old presses being retrofit. Cold foiling uses inexpensive, quickly made printing plates.
COLD FOIL FEATURES:
- Foiling with HOLOGRAMS
- Fast runs speeds
- Short or long print runs
- Anti-counterfeiting security
- Quick turn-around
- Excellent registration
- Fast setup
- In-line and in-house
- Works with a wide range of substrates
After printing cold foil is generally over coated with UV decorative-protective coatings offering a range of finishes from high gloss to matte.
Cork UV coatings for Holographic Cold Foil Wet Lamination are:
- Corkure-2075HG-25MET transfer adhesive
- Corkure-1137HG-21VSMET top coat (no OB)
Cork continues to advance its cost-effective, environmentally responsible GREEN coating technology utilizing sustainable renewable (bio) resource materials content.