Electrochemical Aluminum Hot Stamping Common Faults and Solutions (I)

1, induction shedding

Phenomenon: Under the influence of the temperature of the stamping plate, the aluminum layer of the non-hot stamping part is also detached from the film base. Cause paste version, character, stains and so on.

Cause: The exfoliative layer of anodized aluminum is poorly adapted. If printing plate pressure, temperature and time can be, the imprinting effect is also ideal, but the non-hot stamping part is always excessively exfoliated, especially the hot stamping pattern of the larger type of wide-width pattern, not only the pattern surrounding stains, ring The larger non-printed parts inside also fall off, which is caused by the poor shedding of anodized aluminum.

Plate temperature is too high. When the temperature exceeds the normal temperature and the pressing time is longer, not only the hot stamping part of the adhesive layer is over-dissolved, but also the non-hot stamping part of the printing sheet around the printing plate is baked. At this time, although this part is not under pressure, its sticky material can also contact the printing material, so that the aluminum film is irregularly adhered to the printing material.

The cushion is soft and the plate pressure is too heavy. The cushion is soft and inflexible, and the pressure of the printing plate is very heavy. When the printing plate is imprinted, the cushion material has a large shrinkage and deformation, forming a pit at the embossing, and when the printing is continued, the printing plate is positive. Contact with the aluminum film, the side of the plate is also in contact with the aluminum film, causing the aluminum layer around the pattern on the substrate.

2, shedding is not complete

Phenomenon: refers to the hot stamping of aluminum, the aluminum layer did not fall off from the entire base, but in the color layer of the substrate, there are some small white spots or flower markings.

Cause: Electrochemical aluminum's own ills. Electroformed aluminum film has shortcomings and flower markings. On the aluminum layer, there may be on the adhesive layer, it will cause such problems.

The bottom layer is the improper addition of the ink, and it is a hard block of plastic. In the printing of large area patterns, in order to prevent dirt, add anti-adhesive powder in the ink, these things are both coarse and light, will be suspended in the surface of the ink layer; plastic surface or within the granular powder, hot stamping of aluminum , will stick out, there are blank spots.
The temperature of the hot stamping plate is not enough. The area of ​​the printing pattern is large, and the speed is faster. When the temperature is insufficient, the adhesive layer on the aluminum foil cannot be fully melted. In some places, aluminum ink and paper cannot be completely removed.

Improper process operation. The pressure, temperature, and stamping time of the hot stamping process should be controlled at the optimum point and must be coordinated. If one factor is improperly adjusted, an accident will occur.

There is also the improper tightness of the galvanized steel. It is too loose, and there are stencils, stencils, and stains; too tight, and there will be incomplete shedding. After imprinting, the printing plate and the aluminum film are detached from each other too quickly and can cause malfunctions.

3, color layer is not strong

Phenomenon: Electro-aluminum foil is not firmly bonded after being stamped on the object to be printed. Some products look from the outside after hot stamping, the effect of the hot stamping layer is good, but after friction or collision, the aluminum layer will be partially off.
Cause: Paper is too absorbent. When the paper is hot stamped on paper, the fibrous structure of the paper is too loose, the absorption is very strong, and the adhesive cannot be firmly felted up.

When the ink layer is on the bottom layer, improper auxiliary materials such as petrolatum and wax agent are added to the ink to cause the ink layer to be incompletely dried. When the surface is hot stamped with electro-aluminum foil, the ink cannot be printed on it, or it is barely hot stamped. The layer is loose and falls off.

4, not hot stamping

Phenomenon: Anodized aluminum is not ideally transferred to the object to be printed, ie, the adhesive on the aluminum film does not adhere well to the printed material.

Reason: The adaptability of the aluminum is not good. For different materials to be printed, suitable aluminum should be used. The adhesiveness on the aluminum foil is low and thin, and the surface of the printed material is too dry to be hot stamped.

The paper is more alkaline and too dry, so that the properties of the two do not match. The adhesive cannot sufficiently moisten the paper and thus cannot achieve the desired felting.

The ink layer of the pad crystallizes. When blending, transparent ink etc. is rushed in and a large amount of drying oil is added. After drying, a smooth mirror-like ink layer is formed. Therefore, it cannot be fully compatible with the aluminum foil layer and the hot stamping is not possible. .
The substrate ink layer is too thick. In the superimposed ink layer, especially the pattern which is both flat and bright, the electro-aluminum is stamped, and the hot stamping is not easy to occur. At this point, the ink tightly blocks the paper's voids and forms a thick, dry ink layer.

The comprehensive treatment of the above four hot stamping faults is:

First, remedies are made from the printed materials. Regardless of whether the bottom ink layer is too thick, the surface is crystallized, dried or dried, regardless of the characteristics of the paper, etc., all belong to the fault of the printed object (printed material). Therefore, the remedy method is to use a printing plate (printing plate or bronzing plate) to add a layer of wetting agent, that is, using transparent oil or other binder material as the main body, and then add some substances that are easy to seep or can relieve the effect. Is able to wet the surface of the substrate, in order to facilitate the aluminum foil hot stamping; cover a layer of bright oil. Improper ink layer on the bottom of the pad, or poor suitability of the base paper, can cover many of the above-mentioned problems by merely printing a layer of bright oil formulated with polymer rosin, especially when hot stamping on the edges.

The second is to remedy the problem of anodized aluminum. In other words, the replacement of the aluminum, replaced with suitable for their own use of the nature of the stamping of aluminum. Electro-aluminum species, in essence, is different in the properties of the adhesive layer, different adhesive layers used on the aluminum, and multiple choices. The product performance of each manufacturer is not exactly the same. In addition to the manufacturer's marking of what is suitable for hot stamping on the product, it should be decided after consultation with the manufacturer and trial.

Third, to remedy the process operation. Control the pressure of the printing plate in the hot stamping process, the hot stamping temperature and the stamping time are the core of the hot stamping technology.

In the case of printing a pattern of a large area, if a failure occurs due to falling off, the imprinting speed is appropriately slowed, and the problem may be reduced or completely eliminated.

The surface temperature of the hot stamp must be compatible with the adhesiveness of the aluminum foil and the characteristics of the substrate. The temperature is mainly melt adhesive layer, the high temperature is prone to paste paste, 瞎 character, stains and other defects off the edge; the temperature is low, will cause incomplete fall off, the color layer is not fixed and other problems. Timely and appropriate temperature adjustment is a good way to troubleshoot.

Plate pressure is an important condition for stamping anodized aluminum, and it is also a major factor in ensuring quality. The pressure is too heavy, it is prone to falsing characters, inducing detachment, and other problems. If the pressure is insufficient, it will cause detachment and incompleteness, and failure of the color layer.

In the stamping of electro-aluminum, the cause of the failure is many-sided. Identifying the cause, prescribing the right medicine, and remediating "prevention-based" remedies are only negative methods. Only the selection of electric aluminum, the strengthening of process control, and prevention are the proactive measures.

(to be continued)