Advantages and Disadvantages of Cold Stamping Technology

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At present, hot stamping has become an important method for surface finishing of metallic effects, and it is an effective way to enhance the visual effects of labels, paper boxes, and trademarks, and has been widely used. Hot stamping methods mainly include hot stamping and cold stamping, both of which have their own advantages and disadvantages. In practical applications, the appropriate stamping method is selected according to the specific conditions, especially when weighing the cost and quality. note.

Cold Stamping Technology

Cold stamping technology refers to the use of UV adhesive to transfer the stamping foil to the printing material. The cold stamping process is 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) Peel off the excess hot stamping foil from the substrate and leave the desired hot stamping image on the adhesive-coated area.

When using a dry film cold stamping process, curing of the UV adhesive should be rapid, but it must not be completely cured. To ensure that there is still a certain viscosity after curing, it can bond well with the hot stamp foil.

The wet film-covering cold stamping process is a process in which after the UV adhesive is applied, the UV adhesive is cured after stamping. 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 initial adhesive strength of the UV adhesive is stronger, and will not be cured after curing. Viscosity; Third, the aluminum layer of the stamping foil should have a certain light transmission, to ensure that the UV light can penetrate 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. Advantages and disadvantages of cold stamping technology

(1) There is no need for special stamping equipment. These equipments are expensive.
(2) It is not necessary to make metal hot stamping plates, ordinary flexible plates can be used, the plate making speed is fast, the cycle is short, and the production cost of hot stamping plates is reduced.
(3) Fast hot stamping up to 450fpm.
(4) Energy saving is achieved without heating the device.
(5) The use of a photosensitive resin plate can be used to simultaneously perform the hot stamping of the halftoning image and the solid patch, and the halftone image and the field patch to be hot stamped are formed on the same hot stamping plate. Just as the color patch system on the ground is printed on the same plate, the hot stamping effect and quality of the two may be lost.
(6) Hot stamping substrate has a wide range of applications in thermal materials. Plastic films and in-mold labels can also be stamped.


However, cold stamping technology also has certain deficiencies, mainly including the following two points.

(1) Cold stamping graphics require secondary filming or glazing for secondary processing, increasing the stamping cost and process complexity.
(2) The coated high-viscosity adhesive has poor leveling and is not smooth, which causes diffuse reflection on the surface of the cold stamping foil, which affects the color and gloss of the hot stamping graphic and reduces the appearance of the product.

Although the cold stamping process cannot achieve the high precision and high definition of the hot stamping process, the cold stamping technology can bring many advantages to the flexographic printer, the initial investment of the equipment is less, the plate making cost is lower, and the hot stamping speed is faster , It can be done online on the printing machine. It can be used for hot stamping on materials that are not suitable for hot stamping process (such as film without base film, PET and plastic bags, etc.).

On cold-laminated and non-absorbent paper materials, cold-stamping technology can achieve the best hot-stamping effect. On the contrary, cold-hot-stamping on porous materials with strong permeability is less effective. In addition, some customers can obtain better cold stamping results by applying primers and gluing on matt paper materials.

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