Troubleshooting and influencing factors in hot stamping

The bronzing suitability refers to the selection of anodized aluminum models and the matching of bronzing speed, temperature, pressure and other factors. In the case of equipment and other hardware fixed, correctly grasping the suitability of bronzing is the most important means to improve the quality of bronzing.
1. The hot stamping is not on or the hot stamping is not true

This is related to many factors such as the surface characteristics of the printed parts, the properties of anodized aluminum, the hot stamping temperature and pressure.

1. Too much powder on the surface of the printed part or the surface contains additives such as debonding agent and bright paste, which will hinder the adsorption of anodized aluminum and paper.

Solution: Depowder the surface or solve it in the printing process.

2. Improper selection of anodized aluminum directly affects the bronzing fastness. What type of anodized aluminum should be selected according to the size of the hot stamping area and the characteristics of the material to be hot stamped.

3. Failure to correctly grasp the bronzing equipment and the matching between the bronzing time and the bronzing temperature affects the fastness of bronzing and the clarity of the graphic outline.

Due to the difference of equipment and materials to be stamped, stamping time and stamping temperature are different.

For example, the high-speed circular press is fast, and the embossing line is in contact, and the hot stamping temperature will be higher than the circular or flat press.

In general, the hot stamping temperature for round pressing is 190℃～220℃, round pressing is about 130℃～150℃, and flat pressing is about 100℃～120℃.

Of course, the hot stamping time, hot stamping temperature and production efficiency are still largely restricted by the transfer performance of the anodized aluminum.

 

2. Reverse pull

Reverse drawing means that the anodized aluminum pulls the printing ink or varnish away after hot stamping.

The main reason is that the ink on the surface of the printed product is not dry or the UV on the surface of the printed product is not properly processed, which causes the ink and UV oil on the surface of the printed product to not be firmly bonded to the paper surface.

Solution: bronzing after the printed product is dry. In addition, anodized aluminum with low separation force and excellent heat transfer can be selected.

 

3. Discoloration of the anodized aluminum after paste and hot stamping

Paste plates are mainly caused by poor production of hot stamping plates, loosely installed anodized aluminum, or incorrectly moving the anodized aluminum foil.

The discoloration of the anodized aluminum after hot stamping is mainly caused by the high temperature of the hot stamping.

In addition, the wrinkling of anodized aluminum can also easily cause uneven hot stamping and discoloration, which can be solved by appropriately lowering the temperature.

For the round flattening model, a fan can be installed at the foil feeding place to keep the foil stretched, and avoid the anodized aluminum touching the hot stamping plate and scorching before hot stamping.

 

4. The process arrangement is improper, which destroys the surface glossiness of the anodized aluminum, and the outline of the graphics and text is blurred

For hot stamping that needs to be coated, people often worry that the gold foil is easy to wipe off and first hot stamping and then laminating, which can easily cause:

①Film (especially matt film) will damage the surface gloss of the anodized aluminum, it is not suitable to use water-soluble glue to cover the film, otherwise it will cause the surface of the anodized aluminum to become black, and it is very easy to cause the gold powder to stick to the edge of the graphic and cause the phenomenon of virtuality.

②It is dented due to pressure after hot stamping, and the glue is not easy to penetrate the surface of the anodized aluminum, which will easily cause the OPP to separate from the paper at the hot stamping and affect the product quality.

The correct process is to film and then bronzing, choose anodized aluminum that matches OPP. In short, there are many factors that affect the quality of bronzing. To make high-quality bronzing plates and to correctly grasp the suitability of bronzing is the key to improving bronzing quality.