Thermal-dye-transfer media for labels comprising poly(lactic acid) and method of making the same
AssigneeEastman Kodak Company
InventorsThomas M. Laney, Kenneth W. Best, Jr.
Life of this patent
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Abstract
Thermal-dye-transfer labels, and pre-label media from which they are made, comprising an extruded pragmatic polymer film comprising a microvoided layer, a continuous phase of which comprises a polylactic-acid-based material wherein the microvoids are formed by employing relatively smaller size void initiators, including, for example, various inorganic particles such as titanium dioxide. A method of making sheets for such media is also disclosed involving an extrusion process. High-quality pressure-sensitive labels for application to packages are obtainable by the present invention.
Claims51
A pre-label receiver sheet comprising in order
- (a) a pre-label sheet comprising:
- (i) a polymeric image-receiving layer;
- (ii) a polymer film, either a multi-layer or single layer film, comprising a microvoided layer, in a continuous phase, a polylactic-acid-based material, the microvoided layer having microvoids that provide a void volume of at least 25 percent by volume, wherein at least about half of the microvoids are formed from void initiating particles not more than 1.2 micrometer in average diameter;
- (b) a pressure-sensitive adhesive layer;
- and
- (c) a carrier sheet such that the pressure-sensitive adhesive layer is releasably covered with the carrier sheet in peelable adhesion.
A process for making a pre-label sheet comprising a pre-label sheet and a carrier sheet, which pre-label sheet comprises, in order, a polymeric image-receiving layer, a polymer film, and a bottom pressure-sensitive adhesive layer, which process comprises the following steps:
- (a) providing a pragmatic pre-label sheet by the following steps:
- (i) blending void-initiating particles not more than 1.2 micrometers in average diameter into a first melt comprising a polylactic-acid-based material;
- (ii) coextruding or extruding the first melt to form a cast single-layer or multi-layer film comprising at least one layer made from the first melt;
- (iii) stretching the cast film biaxially to reduce its thickness and to form microvoids around the particles, thereby obtaining an oriented stretched film;
- (iv) optionally applying an intermediate sheet, comprising one or more layers, to a back surface of the oriented stretched film;
- (v) applying a pressure-sensitive adhesive layer, or a laminate comprising a pressure-sensitive adhesive layer, to at least a portion of the back surface of the oriented stretched film, on a side opposite the image-receiving layer, to form a pre-label receiver sheet or, when an intermediate sheet is present, to at least a portion of a back surface of the intermediate sheet;
- and
- (vi) applying an image-receiving layer to the pragmatic polymer film either by coextruding the image-receiving layer with the pragmatic polymer film or by solvent coating the image-receiving layer on the pragmatic polymer film;
- and
- (b) providing the pre-label sheet with a carrier sheet such that the adhesive layer of the pre-label sheet is releasably covered with the carrier sheet in peelable adhesion.
A process for making a pre-label receiver sheet comprising a pre-label sheet and a carrier sheet, which pre-label sheet comprises, in order, a polymeric image-receiving layer, a pragmatic polymer film, and an adhesive layer, which process comprises the following steps:
- (a) providing a pre-label sheet by the following steps:
- (i) blending void-initiating particles not more than 1.2 micrometers in average diameter into a first melt comprising a polylactic-acid-based material;
- (ii) co-extruding a second melt for a polymeric image-receiving layer with one or more other melts for forming a single-layer or multiple-layer polymer film, wherein the one or more other melts includes a first melt for forming a microvoidable layer, thereby forming a co-extruded cast composite film comprising at least the image-receiving layer and the microvoidable layer;
- (iii) stretching in at least one direction the cast composite film to reduce the thickness of the layers in the composite film and to produce an oriented stretched film, wherein the image-receiving layer is less than 15 micrometers thick;
- (iv) optionally applying an intermediate sheet, comprising one or more layers, to a back surface of the oriented stretched film;
- and
- (v) applying a pressure-sensitive adhesive layer, or a laminate comprising a pressure-sensitive adhesive layer, to at least a portion of the back surface of the oriented stretched film, on a side opposite the image-receiving layer, or when an intermediate sheet is present, to at least a portion of a back surface of the intermediate sheet;
- and
- (b) providing the pre-label sheet with a carrier sheet such that the adhesive layer of the pre-label sheet is releasably covered with the carrier sheet in peelable adhesion.
Dependencies are inferred from the claim text.