Nipson Varypress 200, Бумажное руководство

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3-
2
Paper guide
VARYPRESS 200
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3.1.3. Front face characteristics
Recommended paper weight: 80g/m
2
.
Bekk smoothness: More than 20 seconds.
Opacity: More than 85%.
Moisture content: From 3 to 6,5%.
Surface resistivity: From 1010 to 1013 ohms at 100V.
Stiffness: From 0.10 to 0.20 mN x m
Label separation: No separation of label from backing is allowed under the following
conditions:
a) temperature 30ºC, bending radius 25mm, bending angle 135º, time duration 30s;
b) temperature 55ºC, bending radius 35mm, bending angle 90º, time duration 30s.
3.2 LABEL-SPECIFIC FINISHING REQUIREMENTS
When the sheet stiffness is significantly reduced between label rows due to precutting or trimming,
both sheet handling and image quality are affected; the discontinuity in stiffness leads to false folds
in the stacker and to disruption of the image (puffing) at the leading edge of each label.
The following parameters affect this discontinuity:
Trimming
Advantages
Trimming around labels allows continuous verification of label cut quality;
Trimming around tractor holes and fold perforations avoids adhesive in these areas;
Trimming around fold perforations makes stacking easier.
Disadvantages
Trimming around labels creates the stiffness discontinuity described above.
Recommendations
It is advisable to leave a 2 mm trimmed area at each side of the fold perforations and to trim tractor
strips, the labels remaining joined.
If labels must be trimmed, attention must be paid to the following parameters:
- Label layout: the distance between horizontal rows of labels should be minimized (3mm
maximum) .
- Difference in stiffness between label and backing: stiffness of label + backing must not be
significantly greater than that of the backing sheet alone.