Devices for stretching polymer films
Assignee3M Innovative Properties Company
InventorsWilliam W. Merrill, Jeffery N. Jackson, Andrew T. Ruff, Desiree L. Thompson, John A. Wheatley, Jeffrey D. Amundson, Curtis A. Harvey
Life of this patent
Estimating the term…
Abstract
Stretched polymeric films can be used in a variety of applications, including optical applications. The stretching conditions and shape of the stretching tracks in a stretching apparatus can determine or influence film properties. Methods and stretching apparatuses can include adjustable or zone-defined stretching regions.
Claims20
An apparatus for stretching a film, the apparatus comprising:
- a plurality of gripping elements to hold opposing ends of a film;
- opposing tracks along which the plurality of gripping elements travel, the opposing tracks defining a primary stretching region in which the tracks generally diverge to stretch a film held by the gripping elements, wherein each of the opposing tracks in the primary stretching region comprises at least one continuous rail extending the length of the track through the primary stretching region;
- and
- at least one track shape controller coupled to at least one of the continuous rails within the primary stretching region, wherein the track shape controller is capable of applying a force to the continuous rail to modify a shape of the track in the primary stretching region, the track comprising a generally curvilinear segment and a generally linear segment within the primary stretching region.
An apparatus for stretching a film, the apparatus comprising:
- a plurality of gripping elements to hold opposing ends of a film;
- and
- opposing tracks along which the plurality of gripping elements travel, the opposing tracks defining a primary stretching region in which the tracks generally diverge to stretch a film held by the gripping elements, wherein each of the opposing tracks in the primary stretching region is formed between at least two continuous rails extending the length of the track through the primary stretching region, the track comprising a generally curvilinear segment within the primary stretching region.
An apparatus for stretching a film, the apparatus comprising:
- a plurality of gripping elements to hold opposing ends of a film;
- opposing tracks along which the plurality of gripping elements travel, the opposing tracks defining a primary stretching region in which the tracks generally diverge to stretch a film held by the gripping elements, wherein each of the opposing tracks in the primary stretching region comprises at least one continuous rail extending the length of the track through the primary stretching region;
- and
- three or more track shape controllers coupled to at least one of the continuous rails within the primary stretching region, wherein the track shape controllers are capable of applying force to the continuous rail to modify a shape of the track in the primary stretching region, the track comprising a generally curvilinear segment within the primary stretching region.
Dependencies are inferred from the claim text.