How can we remove curling in coating PP/LDPE film on PP substrate?

Response to Blog Query on Curl

There are several actions that can be taken to reduce curl:

• Increase the relative humidity in the drying zone when the coating is in the falling rate zone. This will reduce shrinkage stress from the drying coating, which is causing the curl.

• Increase the relative humidity in space between the end of the dryer and the rewind.

• Plasticize the coating to reduce drying stresses.

• Use a coating on the backside of the substrate. This will counter act the stresses casing curl from the active side of the substrate.

• Consider thicker and higher modulus substrate.

• An increase in web tension can “pull out” some of the curl. However, depending on the physical properties of the substrate, the tension might distort the substrate,