Shrink wrap

Shrink wrap

:"Shrinkwrapped" redirects here. For the album, see Shrinkwrapped (album)."

Shrink wrap, also shrinkwrap or shrink film, is a material made up of polymer plastic film. When heat is applied to this material it shrinks tightly over whatever it is covering.

Shrink wrap is commonly used as an overwrap on many types of packaging: CDs, DVDs, cartons, books, beverage cans, large appliances, pallet loads, etc. It can be the primary covering for some foods such as cheese and meats. It is also used to cover boats after manufacture and for winter storage.
Heat-shrink tubing is used to seal electric wiring.

Shrink bands are applied over parts of packages for tamper resistance or labels. It can also combine two packages or parts.

Composition

The most commonly used shrink wrap is polyolefin. It is available in a variety of thicknesses, clarities, strengths and shrink ratios. The two primary films are either crosslinked, or non crosslinked. Other shrink films include PVC and several other compositions. Coextrusions and laminations are available for specific mechanical and barrier properties for shrink wrapping food.

Current trends are to improve film properties which may lead to reduced caliper (source reduction) and to improve process efficiency (cost and energy savings).

Manufacture

A shrink film can be made to shrink in one direction (unidirectional or mono-directional) or in both directions (bidirectional).

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.

Equipment

Shrink wrap equipment for packaging purposes, is primarily available in two formats.

The first type of shrink wrap machine, used for low to mid-volume packaging, is known as an I-bar sealer. This type of sealer uses one long bar to make single cuts along PVC or polyolefin film. Once the film is cut around a product using the I-bar, the film is typically shrunk using a heat gun, although a heat tunnel can be used.

The second type of shrink wrap machine is used for medium to high-volume packaging. It is known as an L-bar sealer. This is due to the L-shaped design of the cutting bar. The bar only requires one pass to cut film around a product. L-bar sealers can be used in conjunction with a heat gun or heat tunnel to finish shrinking the film around a product.

The wire element used in both types of machines, to cut the film, is often a heated wire or an impulse wire. Heated wires use heat to cut the shrink film. Impulse wires use pulses of electricity to cut the film and generally produce less odor and smoke.

Use

Shrink wrap is applied over or around the intended item, often by automated equipment. It is then sent through a heat tunnel or oven for shrinking. Heat guns are also used for large items.

Shrink wrap can be supplied in several forms. Flat rollstock can be wrapped around a product but centerfolded film is by far the most popular, supplied on a roll the plastic is folded in half: product is placed in the center portion, the remaining three edges are sealed to form a bag, and the package then heated which causes the bag to shrink and conform to the product placed in the bag.Less popular are the pre-formed Shrink bags plastic bags with one end open: the product is placed in the bag, sealed, and sent for heat shrinking.

Shrink wrap can be used to wrap buildings. It is far superior to blue tarps for wrapping roofs after hurricanes, earthquakes, tornadoes and other disasters. Shrink wrap can be used for environmental containments to facilitate safe removal of asbestos, lead and other hazards.

External links

* Flexible Packaging Association [http://www.flexpack.org/]

ee also

*Packaging
*Stretch wrap
*Shrink wrap contract, legal term
*Shrink Rap (disambiguation)

References

* Brody, A. L., and Marsh, K, S., "Encyclopedia of Packaging Technology", John Wiley & Sons, 1997, ISBN: 0-471-06397-5


Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • shrink-wrap — ˈshrink wrap noun [uncountable] tight plastic wrapping for goods: • The plastic shrink wrap prevents tampering. shrink wrap verb [transitive] : • The free gift is shrink wrapped and glued to the magazine page. * * * Ⅰ. shrink wrap UK US noun [U]… …   Financial and business terms

  • shrink-wrap — shrink wrap, shrinkwrap shrink wrap (shr[i^][ng]k r[a^]p), v. t. [imp. & p. p. {shrink wrapped} or {shrink wrapped} (shr[i^][ng]k r[a^]pt); p. pr. & vb. n. {shrink wrapping} or {shrink wrapping}.] to wrap and seal (an object for sale) in a… …   The Collaborative International Dictionary of English

  • shrink-wrap — shrink wrap, shrinkwrap shrink wrap, n. a type of plastic film, usually transparent, that shrinks upon application of heat, and may be used to form a wrapping around objects that fits tightly and closely follows the contours of the wrapped… …   The Collaborative International Dictionary of English

  • shrink-wrap — shrink′ wrap v. wrapped, wrap•ping, n. 1) cvb to wrap and seal in a clear, flexible plastic sheet that when exposed to heat shrinks tightly around the thing it covers 2) cvb the plastic film used to shrink wrap something • Etymology: 1965–70 …   From formal English to slang

  • shrink-wrap — [shriŋk′rap΄] vt. shrink wrapped, shrink wrapping to wrap (a commodity) in a tough, transparent plastic material which is then shrunk by heating to form a sealed, tightfitting package n. a wrapping of such material …   English World dictionary

  • shrink wrap — shrink wrap, a protective plastic cover made by shrink wrapping …   Useful english dictionary

  • shrink-wrap — noun the clinging transparent plastic film that is used to shrinkwrap something • Hypernyms: ↑film, ↑plastic film * * * ˈ ̷ ̷ ¦ ̷ ̷ transitive verb : to wrap (as a book or meat) in tough clear plastic film that is then shrunk (as by heating) to… …   Useful english dictionary

  • shrink-wrap — /shringk rap /, v., shrink wrapped, shrink wrapping, n. v.t. 1. to wrap and seal (a book, a food product, etc.) in a flexible film of plastic that, when exposed to a heating process, shrinks to the contour of the merchandise. n. 2. the plastic… …   Universalium

  • shrink wrap — noun clinging transparent plastic film used to enclose an article as packaging. verb (shrink wrap) enclose in shrink wrap …   English new terms dictionary

  • shrink-wrap — 1. noun a) A plastic film that is used to protect an item and which during application contracts so it tightly enclose it. b) The wrapping around an item that has been shrink wrapped. 2. verb To apply shrink wrap to an item. We spent all day… …   Wiktionary

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”