The Seven Gatekeepers You Must Pass to Achieve Good Adhesion
Did you know that there are seven gate keepers you must pass in order to achieve good adhesion when bonding to plastics?
The Dyne Technology experts have gained this knowledge through over 40 years practical experience solving the problems of adhesion within a multitude of industries throughout the UK and Ireland. Although some of these properties may seem straight forward, they are often overlooked.
To achieve good adhesion, your surface must be…
A prerequisite for good adhesion is that you start off with a clean surface; the most commonly found surface contaminants are found in the form of organic materials. These organic contaminants on the material’s surface prevent your paint, adhesive or ink from making the all-important intimate contact with the substrate to allow adhesion to take place. The CleanoSpector is a surface cleanliness testing instrument for measuring oil, grease and cleaning fluid contamination on metal surfaces, supplied by Dyne Testing.
Having a dry surface requires little discussion, but it is recommended to keep the substrate free from moisture, unless of course using a cyanoacrylate when bonding.
3. Dust Free
Dust can interfere with the adhesive’s ability to make the level of intimate contact with the substrate to allow good adhesion to take place. These dry dust particles are often firmly held to the surface of the material by static electricity, and it is important to remove these dust particles to increase your chances of achieving good adhesion. Removing the static charge should allow easy removal of the dry dust particles.
Contrary to common belief choosing a material that is smooth dramatically improves your chances of improving good adhesion. Why? The rougher a surface, the fewer sites of adhesion there are for the adhesive to bond to. The smoother the surface the more intimate the molecular contact will be between the material surface and the adhesive, ink or coating. In short, having a smooth surface greatly improves the chances of good wetting.
A surface that is non-porous will generally allow the ink, adhesive or coating to wet the surface of the substrate more effectively.
6. Wettability (High surface energy)
Having a high surface energy or good wettability is vital for achieving good adhesion. Put simply wettability is the ability for a liquid to wet a solid. Good wetting allows good spreading of the adhesive, ink or coating.
Testing the wettability of your material is simple using Dyne Test Fluids or Dyne Test Pens. Pens and test fluids come in a series of pre-determined Dyne levels. After applying the test fluids to your material’s surface see if the test ink pulls back or shrinks into droplets, if it does then your material has a lower surface energy value than the test ink applied, if it spreads, it is equal to or more than the value tested.
The most important is saved until last! Having good levels of polarity (one of the components that make up Surface Energy), is arguably one of the most important gatekeepers to achieving good adhesion.
Many materials used throughout UK manufacturing and UK engineering, such as Polypropylene, PE. PEEK, etc., have very low levels of polarity. To measure the polar component of the surface energy an optical Tensiometer (pictured right) can be used. Why do we measure the polar component of surface energy? Low levels of polarity will drastica
lly reduce the chemical affinity when attempting adhesion.
Unlock the door to good adhesion with Dyne Technology
Discover the Plasma Treating key to unlock good adhesion and pass these gatekeepers. Plasma Treating, which is also referred to as Plasma Surface Activation is a highly effective, long lasting method of increasing the surface energy of most materials including plastics, metals, ceramics, glass, wood etc.
If you’d like to find out more, get in touch with the UK and Ireland’s Number One Plasma Treatment Supplier, Dyne Technology. You can speak to one of our technical experts by calling +44(0) 153 411 460 or emailing us at firstname.lastname@example.org.