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US 6,183,856 B2Granted
Opaque polymeric films and processes for making same
AssigneeMobil Oil Corporation
InventorMoris Amon
Life of this patent
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AssigneeMobil Oil Corporation
InventorMoris Amon
Estimating the term…
A process for making an opaque, oriented polymeric film structure and the resultant film structures. The process comprises preparing a melt containing a crystallizable polymeric matrix material at a temperature of at least above the melting point of the polymeric matrix material and thereafter forming the melt into a sheet containing molten polymeric matrix material. The sheet containing molten material is then cooled to form a sheet containing amorphous polymeric matrix material and crystallites of the polymeric matrix material. The sheet while containing the amorphous polymeric matrix material is then formed into a film by stretching the sheet in at least one direction so as to form voids adjacent to at least some of the crystallites and thereby impart opacity to the film. Film structures made by the above process have a plurality of voids, at least some of the voids not containing a void-initiating particle and at least some of the voids being interconnected with an adjacent void in the polymeric matrix material, the number of voids being sufficient to impart a significant degree of opacity in the film structure.
An opaque, oriented polymeric film structure comprising a film consisting essentially of a thermoplastic polymeric matrix material, which film has a first surface and a second surface, the film having a plurality of voids, at least some of the voids not containing a void-initiating particle and at least some of the voids being interconnected with an adjacent void in the polymeric matrix material, the number of voids not containing a void-initiating particle being sufficient to impart a significant degree of opacity in the film structure, wherein said film is made by a process comprising melting and extruding said thermoplastic polymeric matrix material into a sheet, cooling said sheet to form an amorphous polymeric matrix material in which crystallization is initiated but not completed, and orienting the cooled sheet in at least one direction.
An opaque film structure made by a process comprising preparing a melt consisting essentially of a crystallizable polymeric matrix material at a temperature of at least above the melting point of the polymeric matrix material, forming the melt into a sheet consisting essentially of molten polymeric matrix material, cooling the sheet to form amorphous polymeric matrix material and crystallites of the polymeric matrix material, and forming the sheet into a film by stretching the sheet in at least one direction so as to form voids adjacent to at least some of the crystallites and thereby impart opacity to the film.
An opaque, oriented polymeric film structure comprising a film consisting of a thermoplastic polymeric matrix material which has a first surface and a second surface, the film having a plurality of voids but being free of void-initiating particles, and at least some of the voids being interconnected with an adjacent void in the polymeric matrix material.
Dependencies are inferred from the claim text.