The decision was made to use polypropylene (PP) cups for the retail market. To address consumer desire for product visibility and easy access, a clear peelable lidding material was needed. To reinforce the quality image of the brand, it was important that the peel be smooth and consistent. The seal strength needed to be sufficient to provide consumer confidence that the seal integrity had not been breached yet not so strong as to create frustration. They did not want the consumer to need scissors to open the package. The lidding could not string or web when peeled, or leave an unattractive residue on the flange of the tray.
The institutional market was to be served through the use of large high-density polyethylene (HDPE) trays. To allow visual confirmation by the end user of the product in the tray, a clear lidding material was desired. The lidding was to be peelable to allow quick access to the product, yet needed to be strong enough to withstand the rigors of distribution and handling.
In order to compete with the national brands, the food manufacturer knew that cost was a significant issue. They recognized that manufacturing efficiencies would need to be very high with little spoilage or waste. A packaging solution that was cost-effective both in-the-door and out-the-door was required.
Of course, the materials used in the packaging needed to meet the Food and Drug Administration's indirect food additives regulations.
Rollprint Packaging Product's Legato™ lidding film proved to be an excellent solution. Legato consists of an oriented polyester extrusion coated with Allegro® M sealant. It will seal and peel to a variety of cup and tray structures including high-impact polystyrene (HIPS), polyvinyl chloride (PVC), polypropylene (PP) and high-density polyethylene (HDPE).
Because of its wide sealing window and low seal initiation temperature, Legato is a very forgiving material from a manufacturing standpoint. This ensured quick setup times and few machine adjustments, and was one of the primary keys to allowing the manufacturer to meet its waste and efficiency goals. The figure illustrates the seal strength of Legato as a function of sealing temperature.
Legato met this challenge. The sealant system used by Legato was designed to disperse contaminants into fine droplets or particles, providing a smooth peelable seal even under adverse conditions. The table shows the impact on seal strength when sealing through very heavy contamination.
Maintaining the appropriate lidding seal strength until the time of use was a concern for the manufacturer. During distribution and storage, the packaged product would be held refrigerated; in some cases, it was frozen. Experience had taught the manufacturer that many materials that perform well at room temperature do not hold up when subjected to sub-ambient conditions. The seals can weaken or even fail, and the lidding film can become brittle, tearing or breaking when stressed. Careful testing showed that the Legato maintained its excellent performance characteristics across the range of exposure temperatures.
As the manufacturer looked at ways to improve branding, they wanted the option of purchasing the lidding film preprinted with their logo or other brand identifiers. Legato is available surface- or reverse-printed with up to eight colors.
When it came time to qualify the material on the manufacturer's equipment, Rollprint was there to help establish operating windows, assist in any troubleshooting that was needed, provide testing support in their packaging laboratories, and, ultimately, assist with validating the manufacturing process.
The result was a packaging system that was robust, efficient and cost-effective. Waste and spoilage goals were exceeded by more that thirty percent, and the product was successfully launched on time and within budget.
For more information on films, contact Rollprint Packaging Products Inc. at (630) 628-1700 or visit http://www.rollprint.com .