Current Status of Standards for Plastic Composite Film Bags for Food Packaging

What should I do if air bubbles appear in the finished product of the dry laminating machine? Aluminum-plastic vacuum bag

The finished products produced by dry laminating machines often have defects such as bubbles, wrinkles, and weak bonding. There are several ways to avoid air bubbles in the finished product with aluminum-plastic vacuum bags:

(1) Increase the depth of the adhesive or choose an adhesive with good wettability. Adhesives that are too thin or have poor wettability are easy to flow, making the substrate unevenly glued, and prone to vertical or horizontal flow lines. The part with a small amount of glue is likely to have bubbles. You can reduce the generation of bubbles by increasing the concentration of the adhesive or selecting an adhesive with good wettability.

Aluminum plastic vacuum bag

(2) Corona treatment of substrate

Some plastic film substrates have poor adhesion to adhesives. In order to improve the adhesion of such substrates and ensure coating quality, the surface tension of the substrate is required to reach about 42~56Mn/cm, which can be used before coating. Add a corona processor to corona treatment on the surface of the substrate to make the surface fluff to achieve the effect of enhancing the surface tension, so that the amount of glue on the surface of the substrate can be increased to avoid bubbles.

(3) Correct installation and adjustment of the squeegee. When coating, the amount of glue applied mainly depends on the depth of the anilox roll cell. The deeper the cell, the more glue is applied, and the shallower the cell, the less the amount of coating is correct. Adjusting the scraper can ensure that the amount of glue is evenly applied, thereby reducing or avoiding bubbles. In the actual operation process, it is advisable to adjust the pressure of the squeegee with a hammer method. The pressure of the squeegee is generally 200~400kpa. During coating, if the pressure of the squeegee on the anilox roller is too small, when impurities are mixed in , It is easy to top up the scraper to form a gap, making the coating uneven.

Aluminum plastic vacuum bag

(4) Suitable drying temperature

The drying temperature is appropriate, so that the adhesive on the surface of the substrate can be fully dried. Generally, the temperature of the dry bath is adjusted to 80~100℃. The temperature of some baths is too high. The surface of the adhesive has been skinned, and the part below the surface is still If it is not dry enough, it is difficult for the exhaust gas to escape, and foaming is easy to occur. On the contrary, if the temperature of the dry bath is too low, the adhesive cannot be dried. After a period of time of compounding, the finished product will also form bubbles due to the natural volatilization of the adhesive. During compounding, the temperature of the compound heating roller is increased to reduce the compound angle. Facilitate the discharge of air bubbles from the composite membrane.

(5) Adjust compound pressure and speed

If the composite pressure is not enough, it is easy to generate bubbles, and increasing the pressing temperature and composite pressure of the composite film can greatly reduce the bubbles. Since the contact between the two composite rollers is linear contact, reducing the operating speed of the equipment can increase the pressing time between the composite rollers, so that the bubbles can be fully discharged from the composite film, and it is also beneficial to reduce the bubbles.

In addition, to prevent dust from adhering to the composite surface of the film, it is necessary to clean the anilox roller and the film, clean the composite roller, and pay attention to environmental hygiene.What should I do if air bubbles appear in the finished product of the dry laminating machine? Aluminum-plastic vacuum bag

The finished products produced by dry laminating machines often have defects such as bubbles, wrinkles, and weak bonding. There are several ways to avoid air bubbles in the finished product with aluminum-plastic vacuum bags:

(1) Increase the depth of the adhesive or choose an adhesive with good wettability. Adhesives that are too thin or have poor wettability are easy to flow, making the substrate unevenly glued, and prone to vertical or horizontal flow lines. The part with a small amount of glue is likely to have bubbles. You can reduce the generation of bubbles by increasing the concentration of the adhesive or selecting an adhesive with good wettability.

Aluminum plastic vacuum bag

(2) Corona treatment of substrate

Some plastic film substrates have poor adhesion to adhesives. In order to improve the adhesion of such substrates and ensure coating quality, the surface tension of the substrate is required to reach about 42~56Mn/cm, which can be used before coating. Add a corona processor to corona treatment on the surface of the substrate to make the surface fluff to achieve the effect of enhancing the surface tension, so that the amount of glue on the surface of the substrate can be increased to avoid bubbles.

(3) Correct installation and adjustment of the squeegee. When coating, the amount of glue applied mainly depends on the depth of the anilox roll cell. The deeper the cell, the more glue is applied, and the shallower the cell, the less the amount of coating is correct. Adjusting the scraper can ensure that the amount of glue is evenly applied, thereby reducing or avoiding bubbles. In the actual operation process, it is advisable to adjust the pressure of the squeegee with a hammer method. The pressure of the squeegee is generally 200~400kpa. During coating, if the pressure of the squeegee on the anilox roller is too small, when impurities are mixed in , It is easy to top up the scraper to form a gap, making the coating uneven.

Aluminum plastic vacuum bag

(4) Suitable drying temperature

The drying temperature is appropriate, so that the adhesive on the surface of the substrate can be fully dried. Generally, the temperature of the dry bath is adjusted to 80~100℃. The temperature of some baths is too high. The surface of the adhesive has been skinned, and the part below the surface is still If it is not dry enough, it is difficult for the exhaust gas to escape, and foaming is easy to occur. On the contrary, if the temperature of the dry bath is too low, the adhesive cannot be dried. After a period of time of compounding, the finished product will also form bubbles due to the natural volatilization of the adhesive. During compounding, the temperature of the compound heating roller is increased to reduce the compound angle. Facilitate the discharge of air bubbles from the composite membrane.

(5) Adjust compound pressure and speed

If the composite pressure is not enough, it is easy to generate bubbles, and increasing the pressing temperature and composite pressure of the composite film can greatly reduce the bubbles. Since the contact between the two composite rollers is linear contact, reducing the operating speed of the equipment can increase the pressing time between the composite rollers, so that the bubbles can be fully discharged from the composite film, and it is also beneficial to reduce the bubbles.

In addition, to prevent dust from adhering to the composite surface of the film, it is necessary to clean the anilox roller and the film, clean the composite roller, and pay attention to environmental hygiene.