 Magnetic container cover |
| In accordance with the present invention, a flexible cover is provided for a container that is not ... |
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| Ring and closure for cans |
| The easily opened containers representing the state of the art today as outlined above exhibit, ... |
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| Reclosable container |
| OF THE PREFERRED EMBODIMENT A conventional packaging carton for products such as cereal and the ... |
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| Box top lid |
| OF THE PREFERRED EMBODIMENTS Turning now descriptively to the drawings, in which like reference ... |
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| Freshness-preserving container |
| It is an object of the present invention to provide a package of the type described above which ... |
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| Moisture-proof resealable pouch and container |
| OF PREFERRED EMBODIMENTS The pouches, closures and associated containers of the present invention ... |
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| Moisture-proof resealable pouch and container |
| OF PREFERRED EMBODIMENTS The pouches, closures and associated containers of the present invention ... |
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| Microbiological assembly comprising resealable closure means |
| The present invention provides a microbiological assembly which is covered with a resealable cover ... |
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| Single-piece paper cup sip adaptor |
| Referring to FIGS. 1 5 wherein the showings are for purposes of illustrating one embodiment of the ... |
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| Iron oxide pigments |
| We claim: 1. A pigment comprising a non platelet-shaped silica, zirconium dioxide and/or titanium ... |
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Tear resistant multilayer films and articles incorporating such films
| Details |
Inventors: Bland, Ralph H.; Jonza, James M.; Smith, James D.; Allen, Richard C.; Bradley, Jeffrey F.; Smith, Kenneth B.; Stambaugh, Bruce D.;
Assignee: Minnesota Mining and Manufacturing Company (St. Paul, MN)
Primary Examiner: Cannon; James C.
Assistant Examiner:
Attorney, Agent or Firm: Griswold; Gary L., Kirn; Walter N., Skolnick; Steven E.
A tear resistant film comprises more than five layers situated one on the other in a parallel array. The layers are individually selected from a stiff polyester or copolyester, a ductile polymeric material, and optionally, an intermediate material. The stiff polyester or copolyester is oriented in at least one direction. Tear resistance may be measured in a Graves area test and reflects the ability of the film to absorb energy. The films of the invention are useful in many articles including security control laminates for glazing members. |
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DETAILED DESCRIPTION In general, this invention relates to a tear resistant film comprising more than five layers situated one on the other in a parallel array.
The layers occur essentially randomly in the array and are individually selected from a stiff polyester or copolyester and a ductile polymeric material.
Preferably, the stiff polyester or copolyester layers are oriented in at least one direction and, more preferably, are biaxially oriented.
By "tear resistant" it is broadly meant that a film according to the invention demonstrates a Graves area in one direction of the film which exceeds the Graves area in the same direction for a single layer film comprising only the stiff polyester/copolyester of the multilayer film, the single layer film being processed in the same manner as and to substantially the same thickness as the multilayer film.
Preferably, multilayer films according to the invention demonstrate a Graves area in one direction of the film equal to at least about 40+0.
4(x) kpsi % wherein x is the nominal thickness of the film in microns.
More specifically, Graves area is obtained by mathematically integrating the area beneath the curve in a graphical plot of the stress (as measured in kpsi) experienced by the film versus the strain (as measured in Graves elongation which is defined more fully below) that the film undergoes during a test in which a film sample specifically shaped for the Graves area test is clamped between opposed jaws that are moved apart at a constant rate to concentrate the tearing stresses in a small area.
Thus, Graves area is a combined measure of the film's tensile modulus (i.
e.
, the film's stiffness and dimensional stability) and the ability of the film to resist advancing a tear.
Consequently, Graves area may be regarded as a measure of the total energy required to cause the film to fail; that is, the ability of the film to absorb energy.
Moreover, preferred multilayer films desirably exhibit a Graves elongation at break (defined below) of at least 20%, more preferably at least 40% during the Graves area test
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Manufacturing Materials 
