Flexible packaging lamination generates air bubbles, five kinds of situations a net!


Published on:

2017-04-21

In the lamination process, as long as the two layers of film are not completely laminated, there is a difference in transparency, and when the lamination is laminated, the water flow between the film layers is not flat, or the surface energy of the film is not reached, or the amount of glue coating is insufficient, etc., bubbles will follow. In this paper, we mainly elaborate on five kinds of bubbles generated by insufficient glue application, poor drying, blocking, thicker film from the laminating hot rollers with air, uneven laminating hot rollers and pressure rollers, etc., and detail the solutions.

Flexible packaging lamination generates air bubbles, five kinds of situations a net!

In the lamination process, as long as the two layers of film are not completely laminated, there is a difference in transparency, and when the lamination is laminated, the water flow between the film layers is not flat, or the surface energy of the film is not reached, or the amount of glue coating is insufficient, etc., bubbles will follow. In this paper, we mainly elaborate on five kinds of bubbles generated by insufficient glue application, poor drying, blocking, thicker film from the laminating hot rollers with air, uneven laminating hot rollers and pressure rollers, etc., and detail the solutions.

1、Insufficient amount of glue generated bubbles

The amount of glue is not enough is a relative concept, not printed composite film, the amount of glue on 1.8 ~ 2.2g/m2 is enough, printed composite film is better than 2.5-2.8g/m2, of course, we have to use with the structure and product use to determine.

Then, the amount of glue on the factors in addition to the peel strength has an impact on the leveling of its coating is an important factor, and the leveling of the glue coating in addition to the amount of glue on it has an impact on whether the use of uniform rubber rollers, substrates, surface tension of rubber, rubber viscosity will have an impact on it, the comprehensive conditions are good, the amount of glue on the appropriate lower. So we have to do a good job of the above composite conditions before the production of composite, to avoid the problem of bubbles.

2、Bubbles generated by poor drying

Transparent composite film performance is "foggy", poor transparency. Adjustment of drying capacity depends on the drying system of the equipment first, followed by the amount of glue, the greater the amount of glue on the higher the drying capacity requirements. According to the film width and the area of printing ink, also consider the design of the drying temperature gradient, remember the first oven temperature is high.

In actual production, sometimes the drying is very adequate, the amount of glue is also quite a lot, and just under the machine of the composite film or bubbles, in fact, just compounded products without a little bubble is unlikely, small bubbles can be eliminated after maturation, because the solvent-free but not fully cured polyurethane rubber has a certain degree of fluidity, the higher the temperature the greater the fluidity, the greater the molecular weight the smaller the fluidity, the essence of curing is the molecular weight constantly The process of increasing the molecular weight of the composite film in the curing room, the adhesive in the role of temperature slowly leveling, large bubbles shrink, small bubbles disappear, until the increase in the molecular weight of the adhesive to the adhesive can not flow until the generation of composite mesh structure, experienced operators can see how much the white spots can disappear.

If you are not sure, you can put the sample into the oven at 80℃ for 15min to check whether the bubbles are removed. The same size of bubbles can be eliminated by low viscosity adhesive, but not by high viscosity adhesive, because 50% of high viscosity adhesive has large molecular weight and poor leveling, which is why we promote the use of high solid and low viscosity adhesive, Dongchang AD603-75 series, which has high leveling, low viscosity and high transparency. The composite requirements.

3、Blocked version of the bubbles generated

The coating rollers have not been cleaned with a plate washing solution for a long time, resulting in blocked plates. There are two types of blocked plates: one is sudden, due to the poor solubility of the ink and the operation of the transfer rate declining. This type of blockage, such as failure to find the cause of timely exclusion, only by stopping the rubbing version can only be maintained for a while, immediately run out again.

Another kind of blockage is gradual, strictly speaking, can not be considered a failure, because each compound after the residual glue in the anilox rollers can not be completely clean, residual glue day after day in the bottom of the mesh deposited and cured, the amount of glue slowly become smaller, small bubbles are gradually generated, from less to more, from small to large, and finally because one day to do a particularly high product requirements or compound thicker film, small bubbles become unbreakable, when you want to use a special The problem is solved, but it is not a good production habit.

Because a lot of products between qualified and unqualified have been produced before, we advocate measuring the amount of sizing regularly and cleaning the rollers when the amount of sizing decreases to a predetermined value, which is recommended to be cleaned more than twice a week. It is best to use special cleaning solution for cleaning and pay attention to safety. It is best to implement after professional training.

4、Thicker films bring in air from the composite hot rollers and produce bubbles

Thicker film stiffness, if the pressure between the pressure roller and the hot roller is not enough, easy to bring into the air, the simplest solution is to increase the amount of coating.

5, compound heat roller and pressure roller is not flat to produce bubbles 

The uneven place brings in air and produces air bubbles, and these bubbles appear periodically. Another important but easily overlooked cause is the pressure roller bearing part of the two ends of the wear or a tiny bubble, resulting in not parallel with the hot roller, will also produce bubbles.