Composite films are always wrinkled. Is the "real murderer" a material or a craft?

[China Packaging News] Many soft package factories have encountered such a phenomenon: the composite product has horizontal wrinkles, especially at the two ends of the reel. After investigation, it was found that most of the wrinkles were caused by the flatness of one substrate and the formation of " tunnels " by the protrusions of the other substrate . The reason is not the material, but also the craft.

Possible problems with materials:

1. The initial adhesive strength of the adhesive is insufficient;

2. The surface tension of the substrate is insufficient.

Possible problems in the process:

1. Two kinds of base film unwinding tension are not suitable, one is too big and the other is too small;

Example: When BOPP / AL is compounded, if the BOPP tension is too large, the heating in the drying tunnel is elongated, but the AL tension cannot be large, and the elongation rate is small. After the compounding, the BOPP cooling and shrinking causes the aluminum foil to protrude, and then one by one " tunnel " appears horizontally .

2. Insufficient and uneven amount of glue, causing poor adhesion and causing " wrinkles " in local areas ;

3. The winding tension is too small, the winding is not tight, and there is slack after compounding, which provides the possibility of shrinking the substrate to be shrunk.

4. The temperature of the oven is too low and it is not ventilated, the residual solvent is too much, the adhesive is not dried enough, etc., which provides the possibility that the two base films are displaced relative to each other.

The editor reminds you that once the wrinkles of the composite film appear in your factory, you must check the materials and processes one by one according to the above points, find the " real murder " that causes the problem , and formulate a plan for targeted Adjust to avoid the same problem here.