Double-sided tapes are increasingly being used for application in very small devices like smartphones. As these products are becoming increasingly thinner – the most recent smartphones have a thickness of just 7.3 mm (0.3”) – reliable adhesive solutions are required for the accurate positioning of all parts within the case of such high-tech devices. For such applications, very thin films are used which are coated with an adhesive layer and subsequently laminated onto a release liner.
A new spreading approach
For such critical applications, the German company Dreckshage, a manufacturer of linear guidance systems and technical rollers offers a completely new kind of spreader roller.
EcoStretchRoll has been designed and tested by the inventor of the brush spreader roller. The aim of this new development was to improve the performance of spreading devices.
This roller can also be used for thicker substrates up to 150 micron. The EcoStretchRoll is designed for a wide range of adhesive layer thicknesses, web tensions and running speeds of the coating and winding systems and is suitable for substrates such as films, non-wovens, textiles and paper.
Precise spreading ustilising rubber rings
However, compared with other spreader roller systems, the most important innovation is the patent pending precision rubber rings consisting of many individual spreader elements. They allow excellent spreading characteristics even at low wrap angles and without any roller drive or adjustments to the roller.
The special EcoStretch rings are mounted from the centre outwards on the roller. Depending on the roller diameter, each EcoStretch ring consists of 30, 36 or 40 stretch elements that work independently of each other. A single element only weighs 0.5 grams and is therefore very sensitive to any impression pressure of the substrate. Due to the special shaping of the spreading elements, a controlled inclined movement is created in the direction of the roller edge.
A current application
An actual example of an application is where a four micron, biaxia stretched film was coated. With the previous spreader rollers the wrinkling of such thin film substrates could not be completely prevented.
However after switching to the EcoStretchRoll-ST spreader roller from German manufacturer Dreckshage, such problems were eliminated because this spreader roller effectively prevents wrinkling.