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Valley Roller Flexible Packaging


Flexible Packaging

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Cast Film Applications

In cast film processes the elastomeric pressure roller holds the hot extrudate up against the hard coated roller. The objective is to create a specified gauge and surface quality finish from the hard coat and elastomeric covering surfaces as it passes through the nip.

Elastomeric coverings for cast film applications must exhibit a uniform surface, free from all blemishes. The surface finish of the roller is critical since it will create the finish on one side of the substrate. Heat resistance and release properties are also of utmost importance for elastomeric coverings since temperatures in excess of 300° F are most typically involved.

The selection of the elastomeric covering is based upon the following application variables:

  • Heat

  • Pressure

  • Speed

  • Extrudate Tack

  • Film Type

  • Film Mil Thickness

The operating temperature in cast applications has a dramatic impact on the selection process since each elastomeric covering has its own inherent temperature limitation. In applications above (300° F) Silicone roll coverings are typically the material of choice. This can be problematic for many roll manufactures since the industry as a whole has struggled with bonding Silicone coverings for use in elevated temperatures and pressure. Valley Roller has developed a unique family of coverings for cast film applications that can withstand all of the relevant application parameters including pressure and elevated temperatures.

Valley Roller is pleased to offer our novel coverings to the cast film market. Each covering is designed for specific positions within the cast film operation. We believe these coverings offer the reliability and durability necessary to help our customers make better films from the cast process. Please review the chart on the last page for a listing of our product line.

Corona Treater Rolls

Poly films, foil, and other substrates must be treated to accept printing inks or lamination to certain substrates. The most common treatment is a high voltage corona discharge that is applied to the film as it passes over a special roller (Corona Treater). Roll covering materials used on Corona Treaters include Epoxy, Ceramic, Silicone, Hypalon® and EPDM. Valley Roller can assist with proper cover selection. The roll core size is critical to proper cover selection.

Roll coverings must have excellent dielectric strength, ozone resistance, heat and abrasion resistance in order to withstand the Corona Treater environment. They also must be blemish-free or the high voltage applied at the Corona Treating stations will burn through the covering at the point of contamination.

Valley Roller offers several coverings that have been specifically designed for Corona Treater applications. These coverings have been very successful in their own right, but consideration for the operating environment is essential to select the most suitable covering.

The first covering material is based on a Hypalon® elastomer that has been specifically tailored for this application. This covering has outstanding dielectric strength, which enables it to insulate the high voltage encountered at the Corona Treater stations. It withstands temperatures up to 300 degrees Fahrenheit continuous, and has outstanding cut resistance. These properties combine to make it an outstanding Corona Treater roller covering.

The second covering is a Silicone elastomer specifically tailored for this application. This compound has superior dielectric strength when compared to Hypalon® coverings, that enables the cover to insulate the highest voltages encountered at the Corona Treater stations. The cover can withstand temperatures up to 500 degrees Fahrenheit continuous, and has fair cut resistance when compared to our Hypalon® covering. Silicone does provide improved release for films with high cling factors thus reducing the frequency of wrap-ups. Silicone is more thermally conductive than other polymers so the covering thickness can be increased by .040 -.060 for added roll life. This enables end users to re-grind rollers and further enhance the roll life. These properties combine to make silicone an outstanding Corona Treater roller covering when higher dielectric constants are required.

For other types of coatings for Corona Treater rolls, please contact your Valley Roller representative for assistance.

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WISCONSIN
N257 Stoney Brook Road, Appleton, WI 54915-9444
Phone: (920) 733-1991 | Fax: (920) 733-3722

TEXAS
101 Sentry Drive, Mansfield, TX 76063
Phone: (817) 453-8950 | Fax: (817) 453-1501