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In order to choose a self-adhesive label
most suited to your application needs, the selection of
the best label depends on each element which composes the
face material,the adhesive and the backing silicon paper.
Face Stocks
Paper remains the most widely used face
material ,though in recent times filmic stocks have gained
a substantial market share.The most predominantly used varieties
of paper are the uncoated matt,the one side or two side
coated semigloss also known as the chromo art paper and
the cast gloss also known as mirror coat paper. With customer
needs getting to be more specific,it is necessary to use
more modified varieties of paper.
General requirements of the paper include
the surface and mechanical characteristics.
Surface Property
Surface characteristics can be modified
by coating, calendaring metalising, laminating, etc. For non-contact
printing like inkjet a relatively porous surface would be
needed and for other printing processes pigment coated and/or
calendared surface may be required.
Mechanical Property
The strength of the paper is important
(high for faster conversion and waste matrix removal requirements
and low for security labels to achieve tamper
evidence)
Bulk of the papers are in the 70-85 GSM
bracket. However, the labels printers use from films of 15
microns to boards of 300 GSM. An ideal paper would have 6
%. humidity.
Varnishing and lamination also improve
the mechanical strength of the paper.
Synthetic face materials are finding extensive usage, given
the requirement of the no label look & the better aesthetics
exhibited by the film labels. Consider a shampoo bottle
and the harsh environments it has to encounter in its lifespan.
The heat, steam, cold & sometimes dry conditions. Added
to that is the continuous squeezing of the bottle. The paper
alone will not do the job, it will not stretch along with the bottle & return back to its shape, so you will end
up having wrinkled labels, so the surface tension has to
be higher than 40 dynes per cm.
Adhesives
The scenario is fast changing in India. The General
purpose permanent acrylic emulsion adhesive is not enough
these days to service all the segments in labels. With surfaces
becoming diverse & the usage of labels becoming complex,
the selection of adhesive is of prime importance & needs
the continued partnership between the label printer and
the label user. Consideration of the substrates, the conditions
of application, the converting process, the storage &
usage conditions is imperative before deciding on the adhesive.
Release Liner
This is the most performing part of the labelstock. Unfortunately
it lands up in the dustbin as soon as the labels are dispensed
& starts its journey as a part of the final product.
The types of substrates being used to produce release liners
are Glassine, which is popular, super Kraft, Platinum, Synthetic
liners like BOPP, PET, LDPE etc.
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