White Papers

August 1, 2015

Blow-up Ratio

Blow-up ratio or BUR is a term unique to the blown film industry. It is a number that refers to the mathematical ratio of the diameter of a blown film bubble (at its largest point) to the diameter of the extrusion die it comes out of. The higher the BUR, the larger the bubble diameter is in relation to the die.

June 1, 2015

Dialing in the right seal temperature

Trying a new film. How can you speed the process of finding the correct sealing temperature? Unfortunately, there are many variables involved in sealing a film. Some of those are the film or laminate’s thickness, dwell time, pressure, heat transfer and even the type of sealing mechanism being used as well as the configuration (or pattern) of any sealing devices.

June 1, 2015

Changes in film properties over time

What film properties degrade over time and under what conditions should customers store film? The changes that will occur with age are continued slip bloom and a masking of the corona treatment, discoloration, loss of physical properties and blocking or stretching of film. As a result, we typically recommend that customers use PE films in six months or less and honor age-related film failures for that time period only. We also recommend storage in a controlled environment.

June 1, 2015

Coefficient of friction (COF) changes after converting

Examines why the COF of polyethylene film might be different after converting. COF is a measurement of resistance caused by the friction between two moving surfaces. COF is primarily measured as film-to-film and is often referred to as slip.

June 1, 2015

Impact of film thickness on COF

Examines how the thickness of a film, or the gauge, changes the COF value: Slip is added to the polymer and dispersed uniformly throughout the melt. The majority of the slip then migrates to the surfaces and reduces the COF.

June 1, 2015

Troubleshooting sealing properties

If you have questions about the adhesive systems that you are using and how they might affect the seal performance of your polyethylene film, contact your vendor and be as specific as possible. The more information they have about your concerns and experiences, the easier it will be for them to help you. This may help you formulate where to start.