Phenomenon analysis
Dry lamination process, that is, using gravure roller or reversing roller to evenly coat the adhesive dissolved in organic solvent on plastic film, cellophane or aluminum foil. After the solvent is evaporated, other materials to be bonded to the adhesive surface are bonded to form a dry adhesive. Generally, metal roller and rubber roller heated to 60 ~ 80 ℃ are used for lamination, and then cooling gold is used It belongs to roll back coiling compound. The characteristics of dry composite are: almost all materials can be compounded, the combination is free and the selection is wide. By selecting the type and coating amount of the adhesive, the composite film with heat resistance, cold resistance, oil resistance, chemical resistance, gas barrier and transparency can be obtained without oxidation odor, and excellent heat sealing composite film can be obtained. However, after dry compounding, the products are prone to wrinkle and poor adhesion, and the causes are complex, which perplex the composite manufacturers. Now the main reasons are as follows, for peer reference.
Empty wrinkle phenomenon
1. Earthworm like hollow wrinkles appear in the center or edge
reason:
(1) If the tension is not well controlled, the film will shrink after lamination, resulting in one layer of film sagging on the other layer of film, resulting in empty wrinkle phenomenon.
(2) The shape of the film itself is not good, there are wrinkles, relaxation, uneven thickness, wrinkling and other phenomena.
(3) The film surface treatment is not enough or uneven.
(4) The winding operation is wrong.
(5) The molecular weight and cohesion of the adhesive are small.
(6) The mixture of water and ethanol leads to slow curing.
(7) Adhesive coating too much, easy to slip.
(8) The residual solvent in the composite film is too much, which leads to slow curing.
(9) Due to excessive drying, the shrinkage of the film becomes larger, especially the adhesive reaction is too fast to obtain sufficient initial bonding force.
(10) The film is stretched before it enters the roll.

(11) The winding tension is too high.

resolvent:
(1) Master the best tension of various structural films. Because when the tensile film and non tensile film composite, it is easy to appear void wrinkle phenomenon.
(2) Avoid the use of film with poor shape. And avoid deformation of film due to moisture absorption.
(3) The surface treatment degree of the films was tested according to the controllable temperature index.
(4) Pay attention to the change of winding tension. If the tension is too small. If the tension is too high, the film is easy to break. When compounding, the winding tension should be adjusted according to the structure of the film. For stretched films, the tension should be adjusted lower; for non stretched films, the tension should be increased. After the composite film is cooled down, it can prevent the film from shrinking.
(5) Choose high molecular weight, high cohesion, fast curing adhesive.
(6) The ratio of adhesive should be correct, do not mix water and ethanol and other solvents.
(7) Reduce the amount of adhesive coating.
(8) The composite film should be fully insulated and aged.
(9) The best drying conditions were selected. Some films shrink easily at high temperatures. When drying this kind of film, it is necessary to reduce the drying temperature and increase the air volume.
(10) Reduce the sealing temperature and pressure.
(11) Reduce the winding force.
2. After compounding, there is a floating phenomenon of bubble aggregation
reason:
(1) Ink surface absorption of the adhesive, so that the adhesive coating is insufficient, bubble aggregation phenomenon.
(2) Because there are bubbles in the printing ink part of the composite film, and when the adhesive is not fully cured, the air bubbles are accumulated due to extrusion.
resolvent:
(1) Increase the adhesive of high solid differentiation and coating amount, choose good wettability ink and adhesive.
(2) After the adhesive is fully solidified, the composite film is cut to reduce the winding tension after slitting.
3. After compounding, the film appears the empty wrinkle phenomenon from the ink part to the non ink part
Cause: insufficient adhesive coating.
Solution: increase the amount of adhesive coating, choose the ink with good wettability.
Poor adhesion
After coating the adhesive, the bonding strength is not good
reason:
(1) The binder ratio is wrong, the mixing is not good, and the curing agent is not enough.
(2) The adhesive was mixed with solvents such as water and ethanol.
(3) A curing agent which reacts with water and deteriorates during storage is used.
(4) The curing agent reacts with the change of room temperature.
(5) Residual solvents in ink.
(6) The preservation temperature of the composite film is low and the curing is slow.
(7) Low aging temperature reduces heat resistance.
(8) Too much adhesive coating.
resolvent:
(1) The adhesive should be weighed according to the standard proportion, and the usage amount should be recorded to prevent the imbalance.
(2) The adhesive and diluting solvent should be sealed.
(3) Avoid the use of hardener which reacts with water and deteriorates.
(4) The curing agent should be sealed and stored.
(5) Detection of residual solvents in printing film.
(6) The composite film should be fully insulated and aged.
(7) To increase the curing temperature, choose the adhesive which can be cured quickly at low temperature.
(8) Reduce the amount of adhesive coating.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries.
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