In order to choose a self-adhesive label most suited for your application needs, the selection of the best label depends on each element which composes of face material, the adhesive and the backing silicon paper.
Paper remains the most widely used face material, though in recent times filmic stocks have gained substantial market share. The most predominantly used varieties of paper are the uncoated matt, the one side or two side coated semi-gloss 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 characteristics can be modified by coating, calendaring, metalizing, laminating, etc. For non-contact printing like inkjet a relatively porous surface would be needed and for the other printing processes pigment coated and/or calendared surface may be required.
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 are finding extensive usage, given the requirement of the no label look and 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 and 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 and 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
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 and the usage of labels becoming complex, the selection of adhesive is of prime importance and needs the continued partnership between the label printer and the label user. Consideration of the substrates, the condition of application, the converting process, the storage and usage conditions is imperative before deciding on the adhesive.
This is the most performing part of the label stock. Unfortunately it lands up in the dustbin as soon as the labels are dispensed and 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.