VICAT is the temperature at which plastic begins to soften. Productivity and card performance can be greatly affected by the VICAT of core film. Our card overlay and card core sheet is produced to meet the requires.
Printing presses often limit the thickness of film that can be processed.
When print presses have limitations of 400 microns thickness or less, split core construction will be used to produce finished card product. This means printing the front and back of the card on two separate opaque white sheets. The sheets are typically 12 to 13.5 mils each and are solidified during a subsequent lamination process that normally includes the application of a clear overlay film (1.6 to 3 mils) on each side to protect the printed graphics. The critical VICAT temperature for split core cards is that of the two core sheets, because the plastic must soften all the way to the center of each sheet or approximately 15 mils. The VICAT of the overlay is less critical.
Lamination is often a bottleneck work center in the card manufacturing process.
In order to maximize productivity in a split core card construction environment, it is best to choose a core material that has a sufficiently low VICAT temperature so that the core materials will soften and bond together more quickly. Typically, a high ratio copolymer formulation film is preferred. Such a film requires the least amount of lamination processing time, as well as minimizing discoloration or card flowing that may appear in the card once bonded. On the negative side, copolymer films are higher priced than blended or homopolymer films due to higher raw material cost.
In a solid core construction, the front and back graphics are printed on the same sheet. Typically, solid core film construction uses 24 to 26.5 mil opaque white center with the graphics on each side being protected by 1.6 to 3.0 mil overlay film. Since the only bonding required is between the overlay and core/ink surface, which is typically no deeper than 3 mils on either side of the card, the critical VICAT is that of the overlay which must bond to the solid core material. Therefore, a higher VICAT core material can be used. Typically, this core material is a full homopolymer film. Homopolymer material is the most cost effective film to use in card construction and will allow for a quick lamination cycle to enhance productivity in a solid core construction environment.
Low VICAT blended copolymer materials are basically a hybrid between the two extremes of the high ratio copolymer film and a full homopolymer film. The film supplier is attempting to supply the desirable characteristics of a high ratio copolymer film without having the customer absorb the full cost of such a film. The price point is usually between copolymer and homopolymer.
