Polystyrene films in use
Orientation process has licked most of the long-standing problems and brought sparkling, low-cost,
immediate acceptance in window cartons, envelopes and wraps
Logical use of new, high-clarity polystyrene film is in windows for bacon packages. At least seven packers are now using the material in this application because it combines low cost with dimensional stability and sturdy resistance to grease, salt and variations in temperature.
P
• olystyrene film. 20 years on the way, has at last made its entry into the packaging field. A dozen current applications of this crystal-clear film as a bag, wrap and window material demonstrate improved and controlled properties which, with the low cost inherent in this plastic, promise to make it a serious contender in certain areas.
The brittle nature of the early polystyrene film has been transformed by a process of controlled biaxial orientation.1 Today's commercial 1-mil film has the feel and handling qualities of cellophane neither too hard nor too soft. It has the sparkle and
xFor a technical report on this process and its effect, see "Polystyrene Film," p. 154, this issue.
clarity of acetate and the dimensional stability of polyester film. In cost it already challenges the lowest of all, polyethylene.
It has one serious drawback: It is not, at present, truly heat sealable. This was true of polyester film when it was introduced and the problem may be licked in the same way by the addition of a suitable coating although in this case the added cost may be more of a commercial handicap.
The new polystyrene film does not have the great tensile strength of polyester and saran films, but it falls in the good middle range of cellophane and acetate films and is superior to polyethylene. Its burst strength is excellent. It is rated "high" in gas