Cold stamping technology refers to the use of UV adhesive to transfer the stamping foil to the printing material. The cold stamping process can be further divided into dry film cold stamping and wet film cold stamping.
The dry film-covering cold stamping process is to cure the applied UV adhesive before the stamping. Ten years ago, when the cold stamping technology was just introduced, the dry film-covering cold stamping process was used. The main process steps are as follows.
(1) Print cationic UV adhesive on roll printing material.
(2) Curing UV adhesives.
(3) The pressure roller is used to compound the cold foil with the substrate.
(4) Remove the excess hot stamping foil from the substrate and leave only the desired hot stamping image on the adhesive-coated area.
It is worth noting that the use of dry film cold stamping process, the UV adhesive curing should be fast, but can not be completely cured, to ensure that it still has a certain viscosity after curing, so that it can be very hot stamping foil Bonding together well.
The wet film-covering cold stamping process is after the UV adhesive is applied, the first stamping and then the UV adhesive curing, the main process steps are as follows.
(1) Print free radical UV adhesive on web printing material.
(2) Composite cold stamping foil on printing materials.
(3) Curing the radical-type UV adhesive, since the adhesive is sandwiched between the cold-stamped foil and the substrate, the UV light must pass through the foil to reach the adhesive layer.
(4) The hot stamp foil is peeled off from the printing material, and a stamping graphic is formed on the printing material.
It should be noted that: First, the wet film-covering cold stamping process replaces the traditional cationic UV adhesive with a free radical UV adhesive; second, the UV adhesive has a strong initial adhesive force and cannot be cured after curing. Adhesive; Third, the aluminum foil of the stamping foil should have a certain light transmission, so as to ensure that the UV light can pass through and trigger the UV adhesive curing reaction.
The wet film-covering cold stamping process can connect hot stamping metal foils or holographic foils on a printing press, and its application range is also becoming wider and wider. At present, many narrow-width paper boxes and label flexographic printing presses already have such cold hot stamping capability.
1. The advantages and disadvantages of cold stamping technology
The outstanding advantages of cold stamping technology mainly include the following aspects.
(1) There is no need for special stamping equipment, and the prices of these equipment are usually relatively expensive.
(2) It is not necessary to produce metal hot stamping plates, and ordinary flexographic plates can be used. Not only the plate making speed is high, but also the cycle time is short, and the production cost of hot stamping plates can also be reduced.
(3) Fast hot stamping up to 450fpm.
(4) No need for heating devices and energy savings.
(5) The use of a photosensitive resin plate can be used to simultaneously finish the registration of the halftoning image and the on-the-spot color hot stamping. That is, the halftone image and the solid color block to be hot stamped can be formed on the same hot stamping plate. Of course, just like the reconciliation of the real-world color block system to the same printing plate, both the hot stamping effect and the quality may have a certain loss.
(6) The hot stamping substrate has a wide range of applications. Hot stamping can also be performed on heat-sensitive materials, plastic films, and in-mold labels.
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