Minnesota Mining and Manufacturing Company

3M Innovative Properties Company

&num;m Innovative Properties Company

Ronald S Kapaun

Mark A Strobel

Christopher Stewart Lyons

Patrick J Hager

Joan M Strobel

Melvyn C Branch

Seth M Kirk

Embossed oriented thermoplastic films and a method of making same are described. The embossed oriented thermoplastic films have substantially the same mechanical properties as unembossed oriented thermoplastic films. The method includes providing an oriented thermoplastic film having first and second major surfaces, softening at least one of the first and second major surfaces to produce a softened surface, embossing the softened surface to produce an embossed oriented thermoplastic film, and cooling the embossed oriented thermoplastic film.

Method of making embossed oriented polymer films

Embossed oriented thermoplastic films and methods of making them are described. The embossed oriented thermoplastic films have substantially the same mechanical properties as unembossed oriented thermoplastic films. The depth of the embossments ranges from about 1 &mgr;m to about 200 &mgr;m. The methods include providing an oriented thermoplastic film having first and second major surfaces, softening at least one of the first and second major surfaces to produce a softened surface, embossing the softened surface to produce an embossed oriented thermoplastic film, and cooling the embossed oriented thermoplastic film.

Embossed oriented polymer films

The present invention provides a method of modifying the surface of a polymeric substrate, e.g., to improve the wettability of the polymer film surface and/or affix silicon-containing structures to the substrate surface, comprising exposing the substrate to a flame. The flame is supported by a fuel and oxidizer mixture that includes at least one silicon-containing compound that functions as a fuel and is in an effective amount for modifying the surface of the polymeric substrate. Also disclosed are substrates with surfaces that are modified by exposing the substrate to a flame that is supported by the process of the invention. Large increases in the ASTM wetting test, e.g., greater than 13 mJ/m.sup.2 over that reported with conventional flame-treating processes, have been observed in polymeric substrates treated according to this invention.

Flame-treating process

The present invention provides a method of modifying the surface of a polymeric substrate, e.g., to improve the wettability of the polymer film surface and/or alter the reactivity of the surface of the substrate by further oxidation, comprising exposing the substrate to a flame. The flame is supported by a fuel and oxidizer mixture that includes an effective amount, for modifying the polymeric substrate, of at least one oxygen-containing compound that functions as a fuel substitute. Oxygen comprises between about 10 and 50 atomic percent of the compound. Large increases in the ASTM wetting test over that reported with conventional flame-treating processes, have been observed in films treated according to this invention. In addition, significant increases in polymer film surface oxidation levels have been observed.

The present invention provides a method of modifying the surface of a polymeric substrate, e.g., to improve the wettability of the polymer film surface and/or alter the reactivity of the surface of the substrate by further oxidation or affixation of nitrogen, comprising exposing the substrate to a flame. The flame is supported by a fuel and oxidizer mixture that includes an effective amount, for modifying the polymeric substrate, of at least one compound that functions as a fuel or oxidizer substitute and is selected from an oxygen-containing compound, in which the oxygen comprises between about 10 and 50 atomic percent of the compound, a nitrogen-containing compound or an oxygen-nitrogen-containing compound. In a preferred embodiment, which affixes nitrogen or nitrogen-containing chemical groups onto the surface of the film, the flame is supported by a fuel and oxidizer mixture that includes ammonia, nitrous oxide, nitric oxide or a mixture thereof in an effective amount. Large increases in the ASTM wetting test, e.g., greater than 13 mJ/m.sup.2 over that reported with conventional flame-treating processes, have been observed in films treated according to this invention. In addition, significant increases in polymer film surface oxidation levels, e.g., as much as 55 percent, have been observed, as have significant amounts of nitrogen and nitrogen-containing chemical groups affixed to film surfaces.

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Woodbury, MN, United States of America

Ronald S Kapaun