Matrix Removal: A detailed look at some of the technical elements of this important label converting process.

Author:Sahni, Harveer
 
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Waste matrix stripping or removal in the production of self-adhesive labels is a very important part of the label converting process. It is a function that leads to a web of labels that can be dispensed on automatic label dispensers in highspeed packaging lines. Even though it sounds like a simple process of stripping the ladder, the leftover waste after diecutting labels, it remains one of the more complex and problematic areas of label converting.

Matrix breaking or label lifting with the waste ladder represents a challenge, as it may slow down the machine or in some cases make it extremely difficult to remove it online. Converters may have to resort to removing the waste manually off-line, making the process unproductive and costly.

A host of parameters affect the process, and it is difficult to address the issue in a singular way. With so many variables that impact the waste removal process, it is difficult to predict a simple solution. The shape of a label, size of the label, release liner, facestock, adhesive, diecutting process, speed of converting, die blades or the design of the waste removal section could affect the correct and efficient removal at the optimum machine speed. Any of these elements can impact the final result and slow down the machine and the printing process. No one solution can apply to every potential problem.

The traditional waste rewinding system is gradually becoming unpopular due to the fact that tension is the key to efficient waste rewinding. The rewound waste matrix ladder roll has empty spaces from where labels have been diecut, and as the roll becomes bigger there is lots of irregular tension leading to breaks. As the market becomes extremely competitive with the rising prices of labelstocks, printers tend to reduce the gap between the labels to 2mm, making the process even more difficult.

RELEASE LINER

The most widely used base papers as release liners in self-adhesive label materials are glassine, super calendared Kraft and clay coated Kraft. These are uniform caliper, densified and non-porous papers that have adequate strength and accept a uniform coating of silicone, giving excellent release properties to become a proper backing for self-adhesive papers.

In recent years, the possibility of recycling and reducing the tonnage of waste generated has led to filmic liners being used as backing in labels. Release liners play a major role in diecutting, and in turn impact the waste removal process.The die blade has to cut through the...

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