Minnesota Mining and Manufacturing Company

3m Innovative Properties Company

Melvyn C Branch

Mark A Strobel

Christopher Stewart Lyons

Ronald S Kapaun

Michael J Ulsh

James Pezzuto

Domingo Medina

Disclosure is made of methods, systems, and apparatus for changing characteristics of noise of premixed flames supported on burners by heating burner passageways by an amount that attenuates combustion noises arising from premixed flames. Alternatively, attenuation occurs by controlling a temperature differential between a first point relative to a premixed flame and at least a second point in an uncombusted portion of a fuel/oxidizer mixture causing the flame

Attenuating combustion noise of premixed flames

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.

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 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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Boulder, CO, United States of America

Melvyn C Branch