1. Bronzing method
According to the processing method of the self-adhesive label, the hot stamping method is divided into single sheet hot stamping and roll paper hot stamping. Sheet paper hot stamping is the same as the traditional hot stamping process, which is processed on a dedicated hot stamping machine. Roll paper bronzing is done on the label linkage, which is the most widely used processing method. There are several ways to bronze roll materials:
A. Flat pressing and hot stamping on the labeling machine
Regardless of whether the letterpress label printing machine is a flat flattening or a round flattening type device, since the roll paper is fed intermittently, the hot stamping is all flat flattened. Under normal circumstances, the bronzing station is an independent unit, and some models share a unit for bronzing and die-cutting, which are used separately.
B. Multi-station flat pressing and hot stamping
Some models have a two-station bronzing unit. One unit is close to the printing plate to perform horizontal bronzing, and the other unit is an independent unit to perform vertical bronzing. This model can carry out two-color hot stamping at the same time.
C. Flat pressing and hot stamping on the processing machine
The processing machine is specially designed for processing printed roll labels and labels that do not need to be printed. Hot stamping is a function of the processing machine, and the hot stamping device on the processing machine generally adopts a flat pressing method.
D. Round press round hot stamping on the rotary machine
The hot stamping plate used for round pressing and round hot stamping is in the shape of a roller. Round press round hot stamping is suitable for use on continuous paper-feeding roll labeling machines, but it has certain requirements for paper conveying speed, that is to say, it has an impact on printing speed. However, compared with flat bronzing, the efficiency is greatly improved.
E. Cold bronzing on the rotary machine
This is a new hot stamping process. The heated metal printing plate is no longer used, but the method of printing adhesive is used to transfer the metal foil to achieve hot stamping. The process flow is: UV pressure-sensitive adhesive is printed on the position where the printed product needs to be bronzed, the adhesive is dried by a UV drying device, and then a special metal foil is combined with the pressure-sensitive adhesive, and then the metal foil is peeled off. The part of the foil that needs to be transferred is transferred to the surface of the printed matter to achieve cold hot stamping. The cold stamping process has low cost, saves energy, and has high production efficiency. It can use existing equipment components without adding additional devices. It is a promising new process.
2. First bronzing and then bronzing
Self-adhesive hot stamping is divided into first hot stamping and post hot stamping. First hot stamping refers to the first hot stamping on the labeling machine, and then printing; the second hot stamping refers to printing first and then hot stamping at the end. The key to hot stamping and hot stamping is the drying of the ink. There are two situations in the relationship between the bronzing pattern and the printing pattern: side by side and overprint. Due to the different inks used, label printing should adopt two processes: first bronzing and post bronzing.
A. First bronzing process
When the label machine with intermittent paper hot stamping components installed in the front uses ordinary ink to print labels, the first hot stamping process is adopted. Since the ink used is oxidative polymerization drying type, it takes a certain time for the ink layer to completely dry after printing, so hot stamping The pattern must avoid ink. The best way to avoid the ink is to pre-stamp the web material before printing.
The use of the first bronzing process requires that the printing pattern and the bronzing pattern are separated (side by side), because the surface of the anodized aluminum is smooth, not inked, and cannot be printed. Hot stamping can prevent the ink from smearing and ensure the quality of label printing.
B. Post bronzing process
The post bronzing process is applied to the labeling machine where the bronzing parts are installed on the back door, and UV ink is used for printing. The web material is first printed, and the ink is instantaneously dried by a UV drying device, and then the material surface after the ink is dried or the ink surface is bronzed. Since the ink has been dried, the bronzing pattern and the printing pattern can be side by side or superimposed, and the ink smear phenomenon will not occur.
Of the two bronzing methods, post bronzing is the ideal method, which also brings convenience to label pattern design and expands the application range of bronzing patterns. However, due to the limitations of equipment functions, the cost of label printing is relatively high. The first bronzing process is suitable for the processing of small labels with simple patterns, with low cost, and a wide application range. It is a commonly used method in small and medium-sized printing plants.