1, the main reason
(1) The different types of composite substrates, their physical properties are also very different (such as air permeability), the formation of composite film bubbles also has a great relationship. If the two substrate permeability are relatively poor, composite between them, easy to produce bubbles, such as PVDC and BOPA composite. This is due to the two composite substrate air permeability are relatively poor, adhesive in the composite unit gluing system is inevitably mixed with a small amount of air.
(2) In order to make the composite substrate has a certain surface tension, to the surface properties of the substrate to carry out a certain treatment, such as corona treatment, etc., in order to improve the composite substrate surface wettability and improve the roughness, but the roughness exceeds a certain limit, but also difficult to be filled by viscous adhesive. Thus, large and small bubbles are formed between these tiny engaging surfaces.
(3) The viscosity of the adhesive is also an important reason for bubbles. Two-component adhesive use of higher temperatures, mixing and storage time is shorter, the main agent and curing agent ratio is greater, the viscosity of the adhesive is greater, the more unfavorable to the formation of bubbles, and vice versa, the more likely to form bubbles. The same size bubbles, low viscosity adhesive can be eliminated, while the high viscosity adhesive may not work, this is because the high viscosity adhesive molecular weight, poor leveling.

2、Processing methods
(1) Insufficient glue, uneven coating caused by bubbles, in fact, no glue produced by the blank spot, by increasing the appropriate amount of glue can be eliminated. Insufficient glue is a relative concept, the factors that determine the amount of glue in addition to the peel strength, coating the leveling is an important factor. Comprehensive conditions are good, the amount of glue can be appropriately reduced. This appears to be more obvious on the aluminum and white printing film composite.
(2) too much humidity caused by bubbles. The reason is that the adhesive NCO components and water vapor reaction of carbon dioxide gas, too late to precipitate the film and accumulated in the film between the film, can not volatilize through the film to form bubbles. This phenomenon through the production of appropriate control of environmental humidity to solve. General relative humidity below 70%.
(3) Due to insufficient ripening temperature, failed to eliminate air bubbles, should be appropriate to increase the ripening temperature. Cooking room temperature is not higher than 50 ℃, not less than 35 ℃. Composite film a machine without bubbles is relatively rare, and ripening can eliminate small bubbles, because the two-component polyurethane adhesive has not yet cured, the higher the temperature, the greater the mobility, the “second leveling” to a certain extent can be eliminated bubbles.
(4) Ink solvent drying is not sufficient to produce bubbles, is the printing film solvent residue. Generally appear in the ink overprint rate of high part of the overprint rate of low part of the bubble is rare. Production should ensure complete drying before composite. Can also deal with the printing film or reduce the composite speed solution.
(5) equipment process, such as the composite part or the adhesive coating part of the rollers have damage or foreign objects, should replace the steel roller and remove foreign objects.
(6) production process. Mainly includes composite pressure, winding tension, coating temperature and composite temperature. If the composite pressure is too low, should be appropriate to increase the roller pressure. Composite speed is too fast, you can properly reduce the composite speed, or increase the temperature of the nip roller to increase the fluidity of the adhesive. Bubbles caused by dust impurities on the surface of the film should improve the environmental hygiene of the production plant.

Bubble phenomenon
1, the main reason
(1) The different types of composite substrates, their physical properties are also very different (such as air permeability), the formation of composite film bubbles also has a great relationship. If the two substrate permeability are relatively poor, composite between them, easy to produce bubbles, such as composite between PVDC and BOPA. This is due to the two composite substrate air permeability are relatively poor, adhesive in the composite unit gluing system is inevitably mixed with a small amount of air.
(2) In order to make the composite substrate has a certain surface tension, to the surface properties of the substrate to carry out a certain treatment, such as corona treatment, etc., in order to improve the composite substrate surface wettability and improve the roughness, but the roughness exceeds a certain limit, but also difficult to be filled by viscous adhesive. Thus, large and small bubbles are formed between these tiny engaging surfaces.
(3) The viscosity of the adhesive is also an important reason for bubbles. Two-component adhesive use of higher temperatures, mixing and storage time is shorter, the main agent and curing agent ratio is greater, the viscosity of the adhesive is greater, the more unfavorable to the formation of bubbles, and vice versa, the more likely to form bubbles. The same size bubbles, low viscosity adhesive can be eliminated, while the high viscosity adhesive may not work, this is because the high viscosity adhesive molecular weight, poor leveling.

2、Processing methods
(1) Insufficient glue, uneven coating caused by bubbles, in fact, no glue produced by the blank spot, by increasing the appropriate amount of glue can be eliminated. Insufficient glue is a relative concept, the factors that determine the amount of glue in addition to the peel strength, coating the leveling is an important factor. Comprehensive conditions are good, the amount of glue can be appropriately reduced. This appears to be more obvious on the aluminum and white printing film composite.
(2) too much humidity caused by bubbles. The reason is that the adhesive NCO components and water vapor reaction of carbon dioxide gas, too late to precipitate the film and accumulated in the film between the film, can not volatilize through the film to form bubbles. This phenomenon through the production of appropriate control of environmental humidity to solve. General relative humidity below 70%.
(3) Due to insufficient ripening temperature, failed to eliminate air bubbles, should be appropriate to increase the ripening temperature. Cooking room temperature is not higher than 50 ℃, not less than 35 ℃. Composite film a machine without bubbles is relatively rare, and ripening can eliminate small bubbles, because the two-component polyurethane adhesive has not yet cured, the higher the temperature, the greater the mobility, the “second leveling” to a certain extent can be eliminated bubbles.
(4) Ink solvent drying is not sufficient to produce bubbles, is the printing film solvent residue. Generally appear in the ink overprint rate of high part of the overprint rate of low part of the bubble is rare. Production should ensure complete drying before composite. Can also deal with the printing film or reduce the composite speed solution.
(5) equipment process, such as the composite part or the adhesive coating part of the rollers have damage or foreign objects, should replace the steel roller and remove foreign objects.
(6) production process. Mainly includes composite pressure, winding tension, coating temperature and composite temperature. If the composite pressure is too low, should be appropriate to increase the roller pressure. Composite speed is too fast, you can properly reduce the composite speed, or increase the temperature of the nip roller to increase the fluidity of the adhesive. Bubbles caused by dust impurities on the surface of the film should improve the environmental hygiene of the production plant.