Label stock quality control takes a giant leap forward

In this era of ever-increasing online shopping, packages do not find their destinations without labels. Every one of them carries one on the outside but contains several return labels, too. Producers of self-adhesive label stock are busy responding to the growing demand and supplying their products faster and in smaller series. This consequently means a significant increase in the number of grade changes on their laminating machines.

 “To stay efficient you have to be able to produce the   needed grade according to its specifications as soon as   possible. Quality control plays an integral role in ensuring   desired quality, lowering costs and reducing waste,”   says Mikko Talonen, Business Manager, Converting   Solutions, Valmet.

 Valmet has more than 50 years’ experience from   thousands of quality control system deliveries for pulp,   paper, board and tissue production. The Valmet IQ Self-Adhesive Laminating Concept is based on this extensive know-how and represents the most comprehensive quality control system on the market for laminating machines.

“We are now utilizing our automation, measurement and quality control know-how on laminating machines. Since they are more compact and feature different process stages than on paper machines, we have modified our existing products as well as developed new techniques especially for laminated label stock production,” Talonen continues.

The Valmet IQ Self Adhesive Laminating Concept includes Valmet IQ measurements, scanners, profilers, quality controls as well as process and quality vision solutions – all designed to boost quality of label stock.

Water level and curl control without steam

"Compared with other solutions on the market, our moisturizing concept is unique. With today’s fast laminating machines that run over 1,000 m/min, you usually need several steamboxes and conventional moisturizers since their capacities are not very high. Valmet has developed a solution with which all this equipment can be replaced by IQ Moisturizer. It enables you to control both the water level and curl without steam,” Talonen explains.

Whereas older-generation equipment is able to increase the moisture level by less than 1%, IQ Moisturizer can increase it by up to 3%. Additionally, it is possible to control both MD and CD moisture with the Valmet IQ measurements and scanners. Another highlight is closed loop control that ensures unprecedented moisture and curl control accuracy – a totally new feature with moisturizers.

According to Talonen, online closed loop control and multipredictive (MPC) controls are a must on high speed laminating machines to ensure runnability and quality.

And there is the financial side, too. By investing in one IQ Moisturizer, you do not have to invest in steamboxes and an expensive steam approach system. “This amounts to high savings not only in investment costs but also in operating costs. One of our customers recently reported savings of 200,000 euros in annual steam costs,” Talonen adds.

More accurate measurement saves silicone costs

A major role in the Valmet IQ Self-Adhesive Laminating Concept is played by IQ Direct Silicone and IQ Adhesive Measurement and IQ Converting Scanner that ensure accurate sheet quality measurements on silicone coated release liners.
“Another factor that makes this quality solution stand out is our patented technology to measure silicone by using middle infrared (MIR) spectroscopy. Measuring the –CH bonds, present in all silicone and adhesive types, makes it possible to accurately and independently measure silicone without any disturbance of the clay in base paper unlike XRF (x-ray fluorescence) based instruments,” remarks Markku Mäntylä, Research Manager at Valmet. “And as we all know, silicone is expensive, so measurement accuracy is of utmost importance to stabilize release force and lower silicone costs.”

The direct adhesive measurement is able to measure all types of adhesives (solvent, emulsion and hot-melt). It is now possible to control CD variation of adhesive, too.

“According to our customers, the absolutely best feature in the quality control solution is its measurement accuracy. While you earlier had to test paper samples in the laboratory to find out the amount of silicone or adhesive, you can now get accurate quality information online,” Mäntylä continues.

Markku Mäntylä, Research Manager, Valmet

WIS and WMS detect defects and identify root causes

The third important element in this comprehensive quality management concept is Valmet IQ Process and Quality Vision. Consisting of IQ Web Inspection System (WIS) and IQ Web Monitoring System (WMS), it detects quality defects and identifies their root causes.

WIS is a tool to inspect adhesive and silicone defects, laminate and unwinding. It provides new information to reduce the origins of web defects and thus to optimize production quality and efficiency. WMS with its cameras monitors unwinding and coating stations and detects possible adhesive void and streak defects as well as process issues.

”Combining a camera-based system with a quality measurement system makes it possible to combine data from both these sources. This makes troubleshooting and finding root causes easier,” Mikko Talonen concludes.