Surface Treatment Processes
Corona and plasma surface treatment are the most effective methods for improving adhesion on materials resistant to media. These methods of electrical surface treatment are gentle yet powerful in improving the bond strength between substrates and paint, ink, adhesives and coatings.
Many materials have insufficient surface energy for printing and bonding applications. Polypropylene, polyethylene and other polymers are prime examples. These materials have many useful properties, which make them the materials of choice, however, their poor wettability creates severe limitations. That’s where 3DT’s plasma and corona treatment of plastics and other substrates save the day.
Bond strength between media and substrates relies on one specific property: surface energy or surface tension. Surface tension is measured in dyne/cm (mili N/m) and is the deciding factor on how well a liquid adheres to a surface. For a proper bond to exist between a media/liquid and a surface, the substrate’s surface tension must exceed the liquid’s surface tension energy by 2-10 dyne/cm. The higher the surface energy of the substrate in relation to the liquid, the better its ‘wettability’.
How Surface Energy is Measured
To measure the surface energy of a substrate before surface treatment or the effectiveness of corona surface treatment, a tensiometer is often used to determine the contact angle of a solution (typically water) on a substrate. Another quick, inexpensive tool are dyne pens and dyne solution which can assess dyne levels and surface wettability. As shown in the Petri dish image on the left. Learn much more about dyne ink and testing on the Dyne Test Solution tab to the left. 3DT sells these products. Learn more about dyne testing in our Blog article What is Dyne Level.
Also used to measure surface energy is the recently developed automated surface treatment analyzer. This instrument ensures quick, accurate quality control by calculating a substrate’s contact angle at the push of a button, without the risk of human error. The automated analyzer is an excellent tool for reliable, accurate surface treatment validation. Learn more about contact angle as a means of measuring wettability and surface energy on the next page The Corona Process.
Corona and plasma surface treatment are powerful methods for raising surface tension on materials that have poor adhesion. By understanding the science behind surface treatment, even challenging bonding problems can be successfully solved. Read more about the corona process, the plasma process, and the dyne levels needed for strong adhesion on various polymers below:
3DT manufactures a broad line of systems to overcome the bonding difficulties on plastics, rubber, glass, metal, and more. View an introduction to our product line designed for many common surface treatment applications here. All systems can be customized for your needs.
Are you wondering, “Do I need Corona or Plasma?” Give us a call or email us to discuss your application. Read our Blog article Corona vs Plasma here.
Check out this informative article about surface treatment methods and benefits.
Surface treatment: Technology spreading to meet quality demands
By Rob Neilley
Does it sound contradictory that suppliers of surface treatment technology say a technology is spreading steadily into new markets and applications, yet many manufacturing engineers don’t think of it at all? Suppliers say that’s the case. Though it can be an advantage when nothing sticks to a plastic product, it’s a big problem when something should.
Surface treatment, broadly defined, is the modification of a surface to achieve good adhesion between it and something applied or bonded to it. It is useful for plastics because they generally have inherently low surface energy. Adhesives, coatings, ink, labels and paint can’t find enough to hang onto. Treatment increases the surface’s energy and wettability, enabling it to form a strong bond with what is being applied.
See the full article here: Surface Treatment Technology – Plastics Machinery Magazine