The ultimate test determining if the corona treating system is operating is if the end product is acceptable. The accepted methods to determine the level of energy on the substrate are Dyne Test, Contact Angle and Tape Test. The most common of these test methods employs an indicator solution, known as dyne solution, applied to the surface of the treated substrate.
Dyne level testing can be subjective. It is not uncommon for individual interpretations to vary beyond the typical accuracy range of +/- 2 dyne. To minimize interpretation error, Dyne level testing should be performed in accordance the testing methods described by the American Society of Testing and Materials (ASTM D2578-04a). Dyne solution is a mixture of Ethyl Cellosolve and Formamide. The percent concentration of the two chemicals determines the wetting tension, or energy of the solution. The solution usually will contain a dye to allow better visibility when applied to the substrate. Dyne solution is considered a hazardous material, requiring appropriate handling and disposal requirements. The Material Safety Data Sheets are available upon request and are shipped with each order.
The Dyne-Pen Method
This method provides a fast and easy check of the treat level of a substrate using dyne test marker pens. Dyne Pens are pulled across the entire web in a straight line. The pens should have the dyne levels listed on them. As the pen is drawn across the web the operator looks to see that the solid line does not breakup for two seconds. Pens are designed to indicate surface treatment levels on polymer based substrates and establish that the material is correctly treated prior to application.
Although not as accurate as other methods because of possible contamination of the tip by multiple uses, advantages are that it is a quick check, shows the operator which side is treated, and checks for back-treat. Dyne pens have a six month expiration period and must be dated upon first use and the tip sealed immediately after use.
Contact Enercon at 262-255-6070 to order your set of EnerDyne™ pens.
Cotton Swab Applicator Method
Dyne solutions of various concentrations are placed on the substrate until a solution is found that wets out properly. The tip of the applicator swab is immersed in the test solution from a calibrated dyne-level solution container. The solution is spread lightly over approximately one square inch of the test material. If the wetting solution stays intact for two seconds the treat level is at least as high as the dyne level of that solution. Repeat the procedure until a solution is used that will bead up on the surface of the material being tested. The film treat level would be identified as the last solution level that remains wetted out on the surface. A clean cotton applicator must be used for each dyne solution to avoid contamination of the solutions that may distort the results.
This method has been a standard for years but is still somewhat subjective and inconsistent because of the variables involved in the specific applicator swab used and the application of the fluid to the substrate. This procedure should be done in a lab environment because of the risk of spilling the contents of the bottles or leaving the used swabs lying around that could lead to skin contact.
The Draw-Down Test Method
This is the most accurate of the dyne surface-energy measurement tests. A substrate sample, usually measuring 8 1/2 x 11 inches, is clamped to a clipboard. At the top, a single drop of three different level dyne solutions, which bracket the desired treatment level, are placed horizontally from each other. A wire wrapped metering rod is then placed just above the droplets and pulled down. When a film of liquid breaks within the two second period the tester knows that the treat level of the film is below what is written on the dyne solution bottle.
This test tends to be more accurate because the metering rod lays the solutions down at the same relative thickness. The rod must be thoroughly cleaned after each use.