Cold stamping technology refers to the method of transferring hot stamping foil to the printing material using UV adhesive. The cold stamping process can be divided into two types: dry film cold stamping and wet film cold stamping.
The dry lamination cold stamping process is to cure the coated UV adhesive before hot stamping. Ten years ago, when the cold stamping technology was first introduced, the
It is the dry lamination cold stamping process, the main process steps are as follows.
(1) Print cationic UV adhesive on the web printing material.
(2) Curing the UV adhesive.
(3) Use the pressure roller to make the cold stamping foil and the printing material together.
(4) Peel off the excess hot stamping foil from the printing material, leaving only the required hot stamping text on the part coated with adhesive. It is worth noting that when using the dry film cold stamping process, the curing of the UV adhesive should be carried out quickly, but it cannot be cured completely. It must be guaranteed that it still has a certain viscosity after curing, so that it can be very compatible with hot stamping foil It sticks together well. The wet lamination cold stamping process is to apply UV adhesive and then hot stamping and then curing the UV adhesive. The main process steps are as follows.
(1) Print free radical UV adhesive on the web printing material.
(2) Composite cold stamping foil on the printing material.
(3) Curing the free radical UV adhesive, because the adhesive is now sandwiched between the cold stamping foil and the printing material, UV light must pass through the hot stamping foil to reach the adhesive layer.
(4) Peel the hot stamping foil from the printing material, and form hot stamping graphics on the printing material. It should be noted that: first, the wet-laminated cold stamping process uses free radical UV adhesives to replace traditional cationic UV adhesives; second, the initial adhesive strength of UV adhesives is stronger, and can no longer be cured after curing It is sticky; third, the aluminum layer of the hot stamping foil should have a certain transparency, to ensure that UV light can pass through and initiate the curing reaction of the UV adhesive. The wet lamination cold stamping process can be used for hot stamping metal foil or holographic foil on the printing machine, and its application range is becoming wider and wider. At present, many narrow-width carton and label flexo printing machines already have this kind of online cold stamping capability.
1. Advantages and disadvantages of cold stamping technology
The outstanding advantages of cold stamping technology mainly include the following aspects.
(1) No special hot stamping equipment is required, and the price of these equipments is usually relatively expensive.
(2) There is no need to make metal hot stamping plates, and ordinary flexible plates can be used. Not only the plate making speed is fast, the cycle is short, but also the production cost of hot stamping plates can be reduced.
(3) Hot stamping speed is fast, up to 450fpm.
(4) No heating device is required, and energy can be saved.
(5) A piece of photosensitive resin plate can be used to complete the hot stamping of the mesh tone image and the solid color block, that is, the mesh tone image and the solid color block to be hot stamped can be made on the same hot stamping plate. Of course, just as the mesh tone and the solid color block are printed on the same printing plate, the hot stamping effect and quality of both may have a certain loss.
(6) The application range of hot stamping base material is wide, and it can also be used on heat sensitive materials, plastic films, and in-mold labels. However, cold stamping technology also has certain shortcomings, mainly including the following two points.
(1) Graphics and text for cold stamping usually need to be covered or glazed for secondary processing and protection, which increases the cost and complexity of stamping.
(2) The coated high-viscosity adhesive has poor leveling and is not smooth, causing diffuse reflection on the surface of the cold stamping foil, affecting the color and gloss of the hot stamping graphics and text, thereby reducing the appearance of the product.
Mr. J. Michael Rivera, Deputy General Manager of Sales of AMAGICHologrphics, said that 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 flexo printers, including: Less initial investment in equipment, lower platemaking cost, faster stamping speed, can be completed online on the printing machine, and can be used on materials that are not suitable for the hot stamping process (such as films without base, PET and plastic bags, etc.) Hot stamping, etc.
On film and non-absorbent paper materials, cold hot stamping technology can achieve the best hot stamping effect. On the contrary, when performing cold hot stamping on porous materials with strong permeability, the effect is not too ideal. However, Mr. Rivera pointed out that some AMAGIC customers hot stamped on Raflatac Raflasilk matt PSA materials, and the feedback results are also quite good. Some customers can also get a better cold stamping effect by priming and gluing on matt paper materials.
At present, cold stamping technology has become a strong competitor of hot stamping technology, and cold stamping technology is expanding from the narrow-width flexographic printing field to other printing processes, such as wide-format flexographic printing, relief printing, web offset printing and single Sheet offset printing, etc. For example, at Drupa2004, the Roland700 sheet-fed offset press equipped with the new PrindorInLine cold stamping device from Manroland was exhibited.
Cold stamping technology provides new opportunities for printing companies. The biggest advantage is that there is little investment, or no investment at all. Another outstanding advantage is the high cost performance, which is also the biggest selling point of cold stamping technology. As a person in the industry said: "For customers, cold stamping technology has a high cost performance, can help customers increase the added value of products, and is very economical." In addition, because cold stamping technology does not need to make expensive hot stamping plates, Therefore, it is very suitable for the production of short-label and low-quality labels and proofing. However, compared with hot stamping technology, cold stamping technology still has certain defects in quality and needs to be further improved. Therefore, cold stamping technology is not very suitable for the processing of high-quality packaging and label products. By the way, it should be mentioned here that although gold and silver ink printing can also achieve a metallic luster decoration effect similar to hot stamping, and gold and silver ink printing technology has made great progress in recent years, but it still cannot be achieved. The strong visual impact of hot stamping or cold stamping technology.
HAIPENGDA Plastic Toys Co., Ltd. , http://www.hpdtoys.com