Recent Posts
- ANTEC Conference
- Not too technical
- Extrapolation, Comparison and Use of Polymer Melt Viscosity Data using curve fit data
- Melt disturbance onset from increasing line speed
- Viscosity driver of coextrusion melt disturbance
- Coextruding films without defects
- PVC-PET shrinkage and shrink labels
- The impact of polymer density on substrates
- FDA approval of a film
- Curl of coextruded films
Recent Comments
- rakatin on Substrate surface quality
- Eldridge Mount on Temperature profile on a chill roll
- Jimmy on Temperature profile on a chill roll
- Eldridge Mount on Reply to Jimmy's question
- juan on Dimensional stability considerations
Most Commented On
- Matte surfaces (4)
- Differences in film properties and manufacturing methods used to produce them (2)
- Dimensional stability considerations (2)
- Reply to Jimmy's question (2)
- Temperature profile on a chill roll (2)
Archives
Blog
Using matte surfaces
December 25, 2007
I had an interesting comment about problems experienced when printing of a matte-surface PET with a gravure printing system. I have reproduced the question and answer in another posting, but it has prompted me to expand on the use of matte surfaces. My original posting implies the use of the matte surface for appearance, i.e. making the film look flat or paper like. This is easily seen in the market (next trip to the store) where various chip bags have a distinct, flat paper-like appearance next to the glossy chip packaging. But there are other, technical uses for a matte surface which make use of the roughness of the surface.
First, matte surfaces are wonderful to wind. The matte surface roughness acts as an air-entrapping, film-spacing, winding control so that the film-to-film spacing is very uniform wrap-to-wrap which gives a good build to the roll. This is especially true if the matte-surface roughness is larger than the air layer which would have been wound into the roll with the tension in the film. Therefore, the matte surface acts like antiblock particles which are added to films to improve winding. This is an important thing to me, as I have a concept I use in film formulations which I call “formulating for winding.” Formulating for winding helps in improving the roll to roll, slit or mill roll, roll density uniformity, a concept I will discuss in future postings.
Aside from the improvement in winding, the matte surface decreases the layer-to-layer film surface contact in wound rolls, and this will greatly diminish the blocking tendency of a film when wound. This can be important for differential film surfaces where smooth surfaces would block together when wound, destroying the film on unwinding. This antiblocking behavior of the matte surface is used in some two-side treated films where the matte surface, while treated, does not give destructive blocking because of the diminished layer-to-layer contact from the rougher matte surface to the smooth treated surface.
Perhaps the most technical application and use of a matte-film surface is in wound-film capacitors. In this product, the rough, matte-film surfaces are used to both increase the surface area of the film surface but more importantly, to hold the dielectric oil coated on the metallized film before winding into the capacitor. In this case the matte surface also aids in controlling the film-to-film spacing in the capacitor.
Posted by Eldridge M. Mount on December 25, 2007 | Comments (0)