Peeling white liner issue

Khuram asks,

We are experiencing a peel off issue with white 135gsm test liner. This issue is random and the top layer of white liner gets peeled off in the cross direction during conversion. (See the picture below for examples.) We have our own vertically integrated board mill which is providing this white test liner and as far as ply bond strength is concerned we have tested it different lots (using method TAPPI-569) and its average values are >250J/m2.

This issue can have several root causes.

One is that the ink is too tacky and it is pulling the white fibre from the brown base sheet.  It can also be that the ink is drying on the printing plate or otherwise not releasing properly from the plate.

Second is that there could be a poor bond between the white fibre top sheet and the brown base sheet.  This is usually caused by poor fibre developing during the pulping process.  It could also be an issue of poor water drainage in the board making segment.  There could be a contaminated water system, or there may not have been enough starch between the two layers to hold them together.

Sometimes closure tapes can be used in the box plant to predict the ply separation.

So there are a few things that you can look at. Let’s toss this out to our followers and see what they have experienced and information they can offer.

— Ralph

3 Responses to “Peeling white liner issue”

  1. Ian Chalmers Says:

    These are “rollup scuffs” not produced by the printing plates but by the look of it by the feed system. Poor interply bonding, high surface friction and high moisture are variables that lead to producing the rollups as the sheets are feed into the printer.
    You will get them just by feeding the sheets without any printing at all.

    • Khuram Ejaz Says:

      Thank you Ian Chalmers.
      Internal bond of White liner is >250J/m2, Roughness <500ml/min & moisture is about 6.5-8%. Let me know if these parameters are causing it. Also let me know how to avoid this issue
      Moreover, we are facing it at different facilities in different environmental conditions and this issue is very random.

  2. Ola Lindberg Says:

    As Ian write regarding moisture is crusial and also how is the scottbond?
    Concerning moisture what do you have in the stacks and what is the temperature ? i propose that you lower the heat and the amount of glue try to get around 50-60% in relative huimidity after the converting.
    Nextstep can be have less in the infeed etc make as litel stress on the board as possibel

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