The fourth innovative application of hot stamping process

The so-called hot embossed pattern registration is the first process of embossing the aluminum pattern on the surface of the paper and printing the pattern on it. The problem of misalignment between the printed pattern and the hot stamping position often occurs during the implementation of the process. Analyze from the following aspects.

1. Control of paper stretchability

Paper stretching is the most frequent and difficult to control factor in the printing process. In the printing process, it is impossible to completely eliminate the paper expansion and contraction, but it is possible to control the stretching value within a relatively stable range. How to control the retractability of the paper is the basis for implementing the hot stamping pattern registration process.

Newly-introduced papers are generally quite poor in their stability. There are several reasons for this.

(1) The interior of the paper is still in a relatively unstable state (such as how much water content), and it must be allowed to stand for a while before it reaches a stable state.

(2) Changes in ambient temperature and humidity during transportation can also cause changes in the dimensional stability of the paper.

Therefore, for newly-entered paper, the material should be stored in the printing shop for 2 to 3 weeks after the material is opened, so that it can be stretched and deformed to a stable state in the production environment. Then it is wrapped in a shrink film and opened again when it is used.

2. Control of hot stamping process

Pattern positioning and hot stamping is the key to this technology. It is necessary to adopt scientific process plans and statistical principles to complete this process and eliminate as many problems as possible in the bud. Hot stamping can be controlled using the following solutions.

(1) Film positioning method. In the hot stamping process, the film is used for hot stamping, ie, the position of the hot pattern is checked using the film to ensure that the position of the pattern in the paper is correct. In the course of adopting this method, it is necessary to press out the gauge line at the middle edge of the paper, so as to facilitate the stability inspection and post-processing inspection of the hot stamp line.

(2) Outline positioning method. The outline of the pattern to be hot stamped (its size can be slightly improved) is printed with a printing device first with a light-colored outline and then hot stamped against the printed outline. This method is conducive to the machine personnel to detect whether the hot stamping position is accurate.

(3) It is necessary to pay special attention to the fact that during the hot stamping process, it is absolutely necessary to ensure the consistency of the hot stamping two rules (front gauge and side gauge), otherwise the consequences could be disastrous.

3. Control of the printing process

If the above two aspects are all controlled, then the printing process can be done according to "regulations". If there is a problem in the control process, you can use the following measures to remedy.

(1) For paper products that are not handled properly, a humidity control method can be used to record the humidity conditioning time and environmental status of the paper in the form of a table, record the process in detail, and record the humidity treatment process after a successful small batch test. And products for analysis. Then formulate a standardized humidity treatment process plan, implement the process plan, and finally complete the printing process.

(2) If the two rules are not stable in the hot stamping process, then the method of drawing by the line can be used to carry out the division printing (if the hot stamping rules are too chaotic, then the batch of products will be scrapped).

From the above analysis, it can be seen that if the problem is left to be solved in the printing process, it will be in a passive state, so it should be prevented and resolved as soon as possible.

At present, although the hot stamping process is very mature, some unexpected problems still arise in many new application fields. These problems require the printing process researchers to seriously summarize the problems and make unremitting efforts to make the hot stamping more perfect.

Source: "Printing Technology"