Solving adhesion problems is of great importance in several sectors, such as automotive, steel industry, packaging, consumer goods production, electronics and construction materials.
Adhesion problems might be caused by different factors. Among the most frequent we might find insufficient or incomplete cleaning procedures, a lack of protection from oils, grease and detaching agents, deposit of molecules present in the air of the production plant which are caused by other processes and, finally, properties inherent to the treated surfaces.
How to improve adhesion
In order for any material to adhere to a surface, the following factors need to be taken into account:
- composition and properties of the adhesive material and of its surface (if the two possess vastly different properties, adhesion becomes very difficult)
- adhesion value we want to obtain (the highest possible value in most cases, while at times any value below the highest is acceptable)
- surface tension, surface free energy, disperse components and polar components.
Liquids can modify their shape, whereas solids cannot, but they can behave differently when they get into contact with liquids. For instance, when we pour oil on a Teflon (polytetrafluoroethylene) non-stick pan, oil rapidly spreads across the pan’s surface because these two materials interact in a positive way; water, on the other hand, does not adhere well to the pan’s surface and forms little droplets (as Teflon does not interact well with water).
Surface tension and surface free energy are marked by two values:
- disperse particles, which are attracted by other disperse particles (their bond is quite weak)
- polar particles, which are attracted by other polar particles ( their bond is about 10 times stronger compared to disperse particles).
We can determine a low adhesion value by taking the following points into account:
- adhesion value, meaning the strength needed to peel an adhesive off a surface
- interface tension, meaning how well a chemical bond faces the test of time while also conveying that particles might have a hard time forming a bond because they cannot find a corresponding element.
In case of perfect compatibility between the liquid and the surface’s composition, no particle is left out of a bond, resulting in a high adhesion value and a low interface tension value.
On the contrary, when the interface tension value is quite high, many different particles have a hard time forming a bond, due to the different levels of polarity between surface material and coating, thus preventing a bond from standing the test of time.
In order to solve this problem and increase a surface’s polarity, we employ Plasma and Corona treatment.
Ferrarini & Benelli helps companies solving their adhesion problem
Corona and Plasma treatment’s effectiveness depends on the characteristics of the surface undergoing treatment:
- polyester responds well when undergoing surface treatment, immediately showing an increase in the surface tension level
- polyethylene does not respond as well, but increasing its surface tension level is still achievable
- polypropylene does not respond well at all and it shows an increase in its surface tension level only when undergoing treatment at a high level
Over the course of many years, Ferrarini & Benelli has made available their skills to solve adhesion problems of companies producing and dealing printing machines, flexible packaging, plastic films destined to food industry and more, labelling systems, special adhesives to protect cars and industrial tools, which integrate medical and optical devices as well as photographic products.
Ferrarini & Benelli has helped companies to increase their surface tension value, reduce surface contamination as well as adhesion problems and choose the safest, most inexpensive, eco-friendly and technically efficient treatment to best treat plastics and metals.