We hear concerns from customers in terms of gluing on top of OPV. We have heard about skiving as something converters do to make the gluebond stronger.
Questions for you:
- Do you have a sense of how common skiving is – do lots of converters do this or is a niche application?
- Which machinery does the skiving? Is it part of the dye cutter or is it different machinery?
Folding Carton: There is a device called a Skiver, that actually mounts on a Folder/Gluer typically just prior to the Glue application area. Its purpose is, as you suggest, to remove a very thin portion (.001-.003) of the top surface from the substrate to allow a more uniform adhesive bond. The Overprint Varnish may indeed be one of the items that could be removed, if it was not able to be patterned away from the glue flap in the Print process. There are several OEM Folder/Gluer manufacturers that will outfit their equipment from the factory with such a device. It is most common in the manufacture of poly lined inside or outside Folding Cartons, which would then require the Poly Coating or Laminate to be removed to allow proper glue adhesion. A skiver is also available as an after market add on device to facilitate use on many makes and models of equipment. This device can probably be found in about 20-25% of all Folding Carton Plants across North America, since we as a country are very heavily focused on barrier Food Packaging.
Corrugated plants also have the use of these abrasion wheels to remove coatings and surface materials. With new regulations coming down from OSHA on limiting the amount of “dust” in the work environment this is not likely to be a viable solution in the future.
Flexo printing plates are designed to print coatings, inks, and varnish in exactly the designated areas and not flood coat the substrate.
3 thoughts on “Gluing on Top of OPV”
Bobst sells an add-on called PlasmaTreat that shoots a high concentration of plasma (energized electrons separated from atoms). This burnishes the surface and makes it possible to glue even flood varnished panels quite successfully.
There is also a device called a Plasm Treater that performs the same function as a skiver or brush, but because it is only creating a surface capable of sustaining glue and not removing any product, it is a much cleaner operation. This device is suitable for plastics as well as coated paperboard substrates. I believe this product is sold by Bobst in the US and can be installed on virtually any folder-gluer.
Whenever there is a barrier coating material on or in the glue tab area, being certain that the adhesive being used will have an ability to bond strongly to the barrier material. Most adhesives designed for bonding open fiber stocks will fail readily on the coatings that are available in the contemporary market place. There are glue s that are fit for use in these applications, but none of them are “one size fits all” type products. Adhesive manufacturers have labratories that can help you avoid costly errors, if they are asked.