As the professional flexible packing film manufacture ,we would like to introuce some package knowledege. Today let us talk about the factor to effect the transparency requirement of laminated film.
There is a high requirement to the transparency of laminated film in package products.But in the composite processing of plastic film, it has the situation that the laminated is insufficient transparency.
So, what affects the transparency of the laminated film?
Improper selection of adhesive:
If the adhesive itself has a dark color or insufficient fluidity, poor leveling performance, and cannot be fully spread on the composite substrate. The higher the solid content of the main adhesive, the better its fluidity, which is beneficial for spreading on the film. Overall, 75% adhesive has better transparency than 50% adhesive, and 50% adhesive is better than 40% or 35% adhesive. For films with high transparency requirements, it is difficult to achieve the requirements using 50% and 40% adhesive composites.
Processing:
Firstly,the drying temperature of composite machine is too high,which dry too fast result in the quick solvent and wave of liquid surface .The glue premature is easily get together and when the heating power go into the glue inside layer,the solvent under the film will be gasification.This kind of gas break the surface film like volcanic vents, and circles of the ring glue gas makes the glue layer is not transparent.
Secondly, if the press roller or scraper is broken and cause the air pressure point, will also result in the film opaque.
Thirdly,There are too much dust in the air in the working environment,The dust in the hot air are sucked in the drying process after the glue. They are stuck on the surface of the glue layer or in the center of two baseed film, these are also causeing the poor transparency of laminated film .
The solution is useing the high number of filter for the air drying inlet to block the dust absorption.
Finally, the unclean of the adhesive roller will make the laminated film not bright enough.At the same time, the insufficient glue with small bubbles will result in the air spots and opaque.
The solution is to make sure the amount of glue is enough and evenly coated.
Other questions:
The temperature of the composite hot roll is not so high enough ,which can’t melt the glue.The cooling roller temperature is too high and cause the failure to cool suddenly.All of these lead to the poor transparency of the film.
Solution: The temperature of the hot drum shall not be under 70 degrees. The hot melt part of the colloid begins to melt when the temperature reaches 65 degrees.Thus, the transparency and firmness of laminated film are improved.
The cooling roller should use cooling water or chilled water circulation cooling. The faster of the cooling speed, the better transparency we can get. Also,it is benefit to the flatness of the laminated film processing.
Hope all above technical knowledge is useful for you.
Post time: Jul-25-2023
