With the continuous improvement of the national economy, With the rapid development of the printing and packaging industry, people are increasingly demanding high-grade, exquisite, environmentally friendly and personalized. In the post-press processing of packaging products, the hot stamping process has been used by people because of its unique surface finishing effect. favorite.
There are three main functions of bronzing. One is the surface decoration. The image after bronzing shows a strong metallic luster. The color is dazzling and never fades, especially the hot gold and silver. It is decorated with the palatial, exquisite and elegant decoration. Enhance the artistry of the printed products, and play a prominent propaganda effect, and its brightness is much higher than that of the printing gold and the printing silver, so that the products have high-grade texture and enjoy the beauty, greatly increasing the added value of the products; The product has high anti-counterfeiting performance, adopts holographic positioning hot stamping trademark logo, anti-counterfeiting and brand name protection; thirdly, because the bronzing layer has excellent physical and chemical properties, it has a good protection effect on the characters on the printed products.
However, the current bronzing technology still has limitations: the preparation of the hot stamping plate leads to a long hot stamping process, a large number of processes, and high pollution, and it is impossible to realize a large area, a hot stamping, and a ready-to-print. Therefore, the bronzing technology can not be applied to the surface decoration of the publicity carrier commonly used in the advertising industry such as large-format posters, personalized calendars, and roll-ups.
Hot stamping technology review
The most common bronzing processes include hot stamping and cold stamping.
1. The main material of traditional hot stamping hot stamping is electro-aluminum (also known as gold-silver foil or bronzing film). It is based on polyester film, coated with alcohol-soluble dyed resin layer, vacuum-sprayed with metal aluminum, and then coated. It is made of an adhesive layer, which is composed of a base film layer, an alcohol-soluble dyed resin layer (which can be further divided into a separation layer, a dye layer), an aluminum layer and an adhesive layer.
The hot stamping process includes: plate loading → padding → hot pressing → stripping → discharging. The process is mainly to use the principle of hot pressure transfer. Under the action of pressure, the anodized aluminum is in contact with the hot stamping plate and the substrate. The hot stamping plate has a certain heat due to the heating of the electric heating plate, and the electrocalized aluminum is heated to melt the hot melt dyeing resin layer and the adhesive, and the dyeing resin is dyed. The viscosity of the layer is reduced, and the viscosity of the special thermal adhesive is increased after melting. The aluminum layer and the base film are peeled off and transferred to the substrate. With the elimination of the pressure, the adhesive rapidly cools and solidifies, and the hot stamping layer Firmly attached.
Disadvantages of hot stamping technology: hot stamping plate making process is complex, time-consuming, energy-consuming, high-pollution, while the traditional blanching operation is poor.
2. The traditional aluminum foil used in cold bronzing is a kind of special anodized aluminum. The back side is not coated with glue. The adhesive is directly applied to the substrate where the substrate needs to be decorated during printing. When transferred, the electrochemical aluminum is in contact with the adhesive. Electrolyzed aluminum is also attached to the surface of the print under the action of the adhesive.
The cold stamping process includes: plate loading → sizing → cold pressing → stripping → discharging. The process is mainly based on the principle of cold press peeling. Printing UV ink, printing a special adhesive--UV curing adhesive on the surface where the ink surface needs to be bronzing; then removing the moisture of the adhesive to a certain extent through a UV curing device to form a high-viscosity, very thin pressure-sensitive adhesive; Then, the hot stamping is performed, and under the action of a pair of metal rollers, the aluminum foil is brought into contact with the adhesive and pressed into one body. Since the bonding force between the adhesive and the aluminum foil is large, when the waste is discharged, the portion where the aluminum foil contacts the adhesive remains on the surface of the printed matter, and is integrated with the printed matter, and the other portions of the aluminum foil are discharged like the conventional hot stamping.
Disadvantages of cold stamping technology: when applying adhesive on the surface of printed matter, For offset printing , a printing plate must be prepared; if a printing adhesive is used, a special UV flatbed printer must be used.
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