Wor(l)d
is shrinking!
We all know what shrink is! In simplest terms shrink
film is a polymer material which when
heat is applied shrinks tightly over what ever it is covering.
We see it every where on cartons, boxes, crates,
bottles, tin cans, directly on food products, industrial goods, pallets etc.
Where else? Might be wrap boats,
building or even space ships!
Shrink is
available in different forms:- · Wrap
- · Sleeves
- · Bands
- · Bags
The simple logic behind shrink films is that the
films are stretched when they are warm to orient the molecules from their
initial random pattern. Cooling the film sets the film's characteristics until
it is reheated: this causes it to shrink back toward its initial dimensions.
A shrink film can be made to shrink in one
direction (unidirectional or mono-directional) or in both directions
(bidirectional). Shrink can be mono layer or co extruded, to increase the
barrier properties.
The most common equipment for shrink wrapping or
sleeving is a hand held heat gun, just like a hair dryer. Shrink tunnels are
extensively used in semi automated and fully automated lines for shrink
wrapping and sleeving.
Shrink films are mainly Polyolefin’s, PVC, PS.
They are available in different thicknesses ranging from 10 to 75 microns
worldwide. For industrial shrink wrapping like boats , marine etc shrink films
upto 300 microns are used. In India the range is from 12 to 100 microns.
Shrink films are
available in unprinted and printed forms. The over wraps are generally
unprinted and sleeves and bands are printed. The printing can done by roto
gravure or flexo printing up to 10 colors.
