Elastic film containing a renewable starch polymer
AssigneeKimberly-Clark Worldwide, Inc.
InventorsJames H. Wang, Bo Shi
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Abstract
A film that contains a thermoplastic composition having a substantial portion of a renewable, natural starch polymer, and yet is elastic and exhibits good strength properties, is provided. Although starch is normally chemically incompatible with most elastomeric polymers due to their different polarities, the present inventors have discovered that phase separation may be minimized by selectively controlling certain aspects of the film, such as the nature of the elastomeric polymer and the starch polymer, and other film components, the relative amount of the film components, and the process for making the film.
Claims27
An elastic film comprising a thermoplastic composition, wherein the thermoplastic composition comprises at least one starch polymer constituting from about 1 wt. % to about 30 wt. % of the polymer content of the film, at least one elastomeric polymer constituting from about 30 wt. % to about 95 wt. % of the polymer content of the film, wherein the elastomeric polymer includes a metallocene-catalyzed ethylene/α-olefin copolymer, a metallocene-catalyzed propylene/α-olefin copolymer, or a combination thereof having a density of from about 0.85 g/cm3 to about 0.89 g/cm3, a thermoplastic polyurethane synthesized from a polyol and an organic diisocyanate and having a melting point of from about 75° C. to about 250° C., or a combination thereof;
- and at least one plasticizer constituting from about 0.1 wt. % to about 30 wt. % of the film, wherein the weight ratio of elastomeric polymers to starch polymers in the film is from about 1 to about 10, the elastic film exhibiting an elongation in the machine direction and cross-machine direction of about 250% or more.
An absorbent article comprising an elastic film, wherein the elastic film comprises at least one starch polymer constituting from about 1 wt. % to about 30 wt. % of the polymer content of the film;
- at least one elastomeric polymer constituting from about 30 wt. % to about 95 wt. % of the polymer content of the film, wherein the elastomeric polymer includes a metallocene-catalyzed ethylene/α-olefin copolymer, a metallocene-catalyzed propylene/α-olefin copolymer, or a combination thereof having a density of from about 0.85 g/cm3 to about 0.89 g/cm3, a thermoplastic polyurethane synthesized from a polyol and an organic diisocyanate and having a melting point of from about 75° C. to about 250° C., or a combination thereof;
- and at least one plasticizer constituting from about 0.1 wt. % to about 30 wt. % of the film;
- wherein the weight ratio of elastomeric polymers to starch polymers in the film is from about 1 to about 10, the elastic film exhibiting an elongation in the machine direction and cross-machine direction of about 250% or more.
A method for forming an elastic film, the method comprising melt blending a composition comprising at least one starch polymer constituting from about 1 wt. % to about 30 wt. % of the polymer content of the film, at least one elastomeric polymer constituting from about 30 wt. % to about 95 wt. % of the polymer content of the film, wherein the elastomeric polymer includes a metallocene-catalyzed ethylene/α-olefin copolymer, a metallocene-catalyzed propylene/α-olefin copolymer, or a combination thereof having a density of from about a 0.85g/cm3 to about 0.89 g/cm3, a thermoplastic polyurethane synthesized from a polyol and an organic diisocyanate and having a melting point of from about 75° C. to about 250° C. or a combination thereof;
- and at least one plasticizer constituting from about 0.1 wt. % to about 30 wt. % of the film, wherein the weight ratio of elastomeric polymers to starch polymers in the film is from about 1 to about 10, the elastic film exhibiting an elongation in the machine direction and cross-machine direction of about 250% or more, the method further comprising extruding the composition onto a surface to form a film.
Dependencies are inferred from the claim text.