Three main reasons for poor transparency of transparent vacuum bags.vacuum sealer bags for food

1、 Improper selection of adhesive:

(1) The adhesive itself has a deep color;

(2) The adhesive has insufficient fluidity and poor flattening ability, and cannot be fully spread on the substrate.

Generally speaking, the higher the solid content of the main agent, the better the fluidity, which is conducive to spreading on the film. Therefore, currently, 75% adhesive has better transparency than 50% adhesive in the market, with 50% better than 40%. For composite films with high transparency requirements, both 50% and 40% adhesive are difficult to meet.

2、 Process issues:

(1) The temperature at the entrance of the drying channel is too high or there is no temperature gradient, and the temperature at the entrance is too high and the drying is too fast, causing the solvent on the surface of the adhesive layer to evaporate quickly and form a crust. Then, when the heat penetrates into the interior of the adhesive layer, the solvent under the film vaporizes and breaks through the adhesive film to form a ring like a volcanic vent, which makes the adhesive layer opaque.

(2) There is a defect in the composite rubber roller or scraper, which cannot be pressed at a certain point, forming a gap and opaque.

(3) There is too much dust in the ambient air, and there is dust in the hot air blown into the drying duct after gluing. Sticking to the surface of the adhesive layer, sandwiched between two base films during lamination, there are many small spots that cause opacity. Solution: The air inlet can be cleaned with a high mesh filter screen to eliminate dust in the hot air.

(4) Insufficient amount of glue applied. If there is a blank area, there may be small air bubbles, which may cause a pattern or opacity. Please check the amount of glue applied to ensure it is sufficient and even.

(5) No spreading roller or unclean spreading roller.

3、 Reason for substrate:

The surface tension is not high, and the wetting ability of the adhesive is not enough. After drying, the adhesive film becomes uneven, bit by bit, commonly known as the "pockmarked face film".

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