Reasons and solutions affecting the transparency of protective tape for aluminium

Improper selection of adhesive

If the adhesive is darker in color or has insufficient fluidity, the leveling performance could be better and be fully spread on the laminated protective tape for aluminum. Generally, the higher the solid content of the leading adhesive, the better the fluidity is conducive to spreading on the film. 75% of the glue is better than 50% of the transparent effect, and 50% is better than 40% or 35% of the glue. Laminating with 50% and 40% adhesives is challenging for protective tape for aluminium with high transparency requirements.

Problems in the process

Firstly, the temperature of the baking channel of the laminator is too high; the drying is too fast, the solvent of the surface layer of the glue is volatile (evaporation), the glue surface crusts too early, then when the heat penetrates the interior of the glue layer, the solvent below the glue film will be vaporized, when the gas rushes through the surface of the glue film to form a volcano like a crater, a circle of rings, which makes the glue layer is not transparent enough. Secondly, if the compliant pressure roller or scraper has defects, a particular point of pressure is not solid, and the formation of space will also cause the film after the compliance is not transparent.

Here to join the working environment of the air in the dust is too much; after gluing the hot air sucked in the drying channel, there is also dust sticking to the surface of the adhesive layer or composite when sandwiched between the two layers of base film, a lot of dust caused by opacity or poor transparency.

The solution is a closed laminating machine on the part of the glue, drying channel air inlet with a high mesh number of filters, blocking the dust sucked in (that is, clear drying channel hot air in the dust).

In addition, there is no spreading roller, or the spreading roller is not clean; it will make the film after the composite is not translucent enough, or the composite on the amount of glue is not enough, uneven glue blanks, a folder with tiny bubbles, resulting in spots or opaque.

The solution is to check and adjust the amount of glue so that it is enough and evenly coated, resulting in what is commonly known as "hemp face film."

Other Problems

It should be noted that the temperature of the laminating hot drum is not high enough, the hot melt part of the adhesive is not melted, the temperature of the cooling roller is too high, and it is not possible to cool it suddenly, all of which can lead to the film's poor transparency.

Solution: the temperature of the hot drum should not be lower than 70 degrees; the hot melt part of the gel will start to melt only when the temperature reaches 65 degrees; after melting, not only will the transparency be improved, but also the composite firmness will be increased. Cooling rollers should be cooled by cooling water or chilled water circulation; the faster the cooling speed, the better the transparency, the better the flatness of the composite film, and the better the firmness.