Improper selection of adhesive:

       If the adhesive itself is darker in colour or has insufficient fluidity, the levelling performance is poor and cannot be fully spread on the laminated base film. Generally the higher the solid content of the main adhesive the better the fluidity, which is conducive to spreading on the film. Overall, 75% of the glue is better than 50% of the transparent effect, 50% of the glue is better than 40% or 35% of the glue. For conforming films with high transparency requirements, laminating with 50% and 40% adhesive is difficult to meet the requirements.

Problems in the process:

       First of all, the composite machine baking channel temperature is too high, drying too fast all right glue surface solvent rapid volatility (evaporation), glue premature surface crust, and then when the heat penetrates into the interior of the glue layer, the solvent below the film will be gasification, when the gas rushes through the surface of the skin film to form a volcano like vents, a ring of rings, but also to make the glue layer is not transparent enough. Secondly, if the compliant pressure roller or scraper has defects, a certain point of pressure is not solid, the formation of the gap, will also result in compliance with the film is not transparent.

 Here to join the working environment of the air in the dust is too much, on the glue after the baking channel sucked in the hot air there is also dust, sticking to the surface of the adhesive layer or composite clamped in the middle of the two layers of base film, a lot of dust caused by opaque or poor transparency. The solution is: 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 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 with blank space, folder with small air bubbles, resulting in spots or opaque. The solution is: 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 composite heat drum is not enough, the hot melt part of the glue is not melted, the temperature of the cooling roller is too high, can not be cooled suddenly can cause poor transparency in line with the film.

     Solution: the temperature of the hot drum shall not be lower than 70 degrees, the hot melt part of the gel body when the temperature reaches 65 degrees before it starts to melt, after melting, not only improve the transparency, but also increase the composite firmness. Cooling rollers should use cooling water or chilled water circulation cooling, the faster the cooling speed, the better the transparency, the better the flatness of the composite film, the better the firmness.