CN107567392B - Conductive thermal imaging receiving layer with receiver overcoat - Google Patents

Abstract

The present invention relates to a conductive thermal image receiver element having an aqueous coatable dye-receiving layer and an aqueous coatable receiver overcoat layer. The receiver overcoat layer comprises a conductive polymeric material and two or more dispersants. The dye-receiving layer comprises a water-dispersible release agent, a crosslinking agent, and a polymeric binder matrix consisting essentially of a water-dispersible polyester and a water-dispersible acrylic polymer. The invention also relates to methods for making such thermal image receiver elements and methods of using the elements to provide dye images by thermal transfer from donor elements.

Description

Conductive thermal imaging receiving layer with receiver overcoat

Cross Reference to Related Applications

This application claims the benefit of U.S. provisional application No. 62/155,906 filed on 5/1/2015.

Background

The present invention relates to conductive thermal image receiver elements for thermal printing. In recent years, thermal transfer systems have been developed to obtain printed images from pictures that have been produced from cameras or scanning devices. According to one method of obtaining such printing, the electronic picture is first subjected to color separation by means of color filters. The corresponding color separated image is then converted into an electrical signal. These signals are then transmitted to a thermal printer. To obtain a print image, a blue, magenta, or yellow dye donor element is placed face-to-face to the thermal image receiver element. Both are then inserted between the thermal print head and the platen roller. A line thermal print head is used to heat from the back of the dye donor sheet. The thermal print head has a plurality of heating elements and heats in sequence in response to one of a blue, magenta, or yellow signal. The process is then repeated for the other colors. A color hardcopy is thus obtained, which corresponds to the initial picture viewed on the display screen.

Various approaches have been proposed to provide thermal dye receiving layers. Solvent coating of dye image-receiving layer formulations is a common approach. However, the use of solvents to coat these formulations presents a number of problems, including expense, environmental and waste issues, and hazardous manufacturing processes. Special precautions are required to address these problems. Another approach involves hot melt extrusion of the dye image-receiving layer formulation onto a support. Multiple layers may be coextruded in the preparation of the thermal image receiver element. Such methods are extremely efficient in making suitable thermal image receiver elements, but they limit the types of materials that can be incorporated into the dye image-receiving layer due to the high temperatures used in the extrusion process. Yet another approach is to use an aqueous coating formulation to prepare the dye image-receiving layer. Such formulations typically include a water-soluble or water-dispersible polymer as the adhesive matrix.

While aqueous coating methods and formulations are desirable for the reasons mentioned, aqueous coated dye image-receiving layers can present problems in typical customer printing environments where high speed printing requires smooth separation of the dye donor element from the thermal image receiver element without adhesion between the contacting surfaces of the two elements. Printing such images in higher humidity environments can be particularly troublesome because of the tendency to stick to the aqueous-coated dye image receptor layer. In addition, such thermal image receiver elements are often deficient in providing sufficient dye density in the thermally formed image. The aqueous coating layer may also crack when contacted with water. The industry has actively dealt with these problems with a number of proposed solutions described in the literature.

Despite all known approaches to the various problems associated with the use of aqueous coated dye image-receiving layer formulations, there remains a need to improve the resistance of such formulations (and the dried layers obtained therefrom) to relative humidity variability so that the resulting images are consistent and exhibit sufficient density, regardless of the relative humidity in the thermal dye transfer element being stored or used.

Disclosure of Invention

The present invention relates to a conductive thermal image receiver element having a water-based coatable dye-receiving layer comprising a release agent, a cross-linking agent, a water-dispersible acrylic polymer, a water-dispersible polyester, and a water-dispersible conductive polymeric material. The present invention further relates to a conductive thermal image receiver element having a water-based coatable dye-receiving layer comprising a release agent, a crosslinking agent, a water-dispersible acrylic polymer, a water-dispersible polyester, and a receiver overcoat layer comprising a water-dispersible conductive polymeric material. Additionally, a surfactant may be added to the receiver overcoat layer, or an excess of surfactant may be added in the manufacture of the water-dispersible acrylic polymer. The invention also relates to methods for making such thermal image receiver elements and methods of using the elements to provide dye images by thermal transfer from donor elements.

For example, the conductive thermal image receiver element may include a support and have on at least one side of the support: an electrically conductive layer comprising an outermost layer, wherein the outermost layer is an aqueous coatable dye-receiving layer having a thickness in the range of 0.1 μm to 5 μm, and wherein the aqueous dye-receiving layer comprises a water-dispersible release agent, a crosslinking agent, and a polymeric binder matrix consisting essentially of: (1) a water-dispersible acrylic polymer comprising chemically reacted or chemically non-reacted hydroxyl, phosphonate, sulfonate, carboxyl, or carboxylate groups; (2) having a T of 30 ℃ or less than 30 DEG C_gThe water-dispersible polyester of (a), wherein the water-dispersible acrylic polymer is present in an amount of at least 55% by weight of the total aqueous coatable dye-receiving layer weight and is present in a dry ratio to the water-dispersible polyester of at least 1: 1; and (3) a water-dispersible conductive polymer material.

The water dispersible conductive polymeric material may be present in the aqueous dye-receiving layer in an amount in the range of 0.75 wt% to 2.0 wt%, or in an amount in the range of 1.0 wt% to 1.25 wt%, or in an amount in the range of 0.75 wt% to 1.5 wt%.

The conductive thermal image receiver element can additionally have any one or more of the following features. The water-dispersible acrylic polymer may contain chemically reacted or chemically non-reacted carboxyl or carboxylate groups and may be crosslinked via hydroxyl or carboxyl groups to give amino ester, urethane, amide or urea groups. The water-dispersible acrylic polymer may further comprise repeating units derived from: (a) one or more ethylenically unsaturated polymerizable acrylates or methacrylates comprising an acyclic alkyl, cycloalkyl or aryl ester group having at least 4 carbon atoms, (b) one or more carboxyl-or sulfonic acid group-containing ethylenically unsaturated polymerizable acrylates or methacrylates, and (c) optionally styrene or styrene derivatives, wherein (a) the recurring units represent at least 20 mol% and up to and including 99 mol% of the total recurring units, and (b) the recurring units represent at least 1 mol% and up to and including 10 mol%. Typically, the water-dispersible acrylic polymer is present in an amount of at least 55 weight percent and up to and including 90 weight percent of the total aqueous coatable dye-receiving layer weight. Alternatively, the water-dispersible acrylic polymer may be present in an amount of at least 60% and up to and including 90% by weight of the total dry image receiving layer weight. The weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in the polymeric binder matrix is from 1:1 up to and including 20:1, or more specifically 4:1 up to and including 15: 1.

The water-dispersible polyester has a T of at least-10 ℃ and up to and including 30 ℃_gAnd the dye image-receiving layer itself has a T of at least 35 ℃ and up to and including 70 ℃_g. The outermost layer of the thermal image receiver element has a dry thickness ranging from 0.8 μm to 2.0 μm, or 1.2 to 1.4 μm, or 0.1 μm to 5 μm.

Typically, the support is a polymeric film or a resin coated cellulose paper base, a microvoided polymeric film or wherein the support comprises a cellulose paper base or a synthetic paper base. The conductive thermal image receiver element of the present invention may be a single-sided or duplex thermal image receiver. Duplex thermal image receiver elements typically comprise the same or different aqueous coatable dye-receiving layers on two opposing sides of a support. The aqueous coatable dye-receiving layer may be disposed directly on one or both opposing sides of the support. Alternatively, the conductive thermal image receiver elements of the present invention may comprise one or more intermediate layers between the support and the aqueous coatable dye-receiving layer on one or both opposing sides of the support.

Referring now to the water-dispersible release agent included in the aqueous dye-receiving layer, suitable release agents are selected from the group consisting of: a water-dispersible fluorine-based surfactant, a silicone-based surfactant, a modified silicone oil, a polysiloxane, a modified polysiloxane, and a crosslinked amino-modified polydimethylsiloxane. More specifically, the water-dispersible release agent can be a polysilicone modified with amino side chains or terminal groups and is present in an amount of at least 1 to 3 weight percent based on the total dry image receiving layer weight. Alternatively, the water-dispersible release agent can be a water-dispersible polyalkylene oxide-modified dimethylsiloxane graft copolymer having at least one alkylene oxide pendant chain having greater than 45 alkoxide units. Typically, the water-dispersible release agent is present in an amount of at least 1.0 wt% to and including 5 wt% based on the total dry image receiving layer weight.

Referring now to the crosslinking agent contained in the aqueous dye-receiving layer, such crosslinking agent may be a carbodiimide or aziridine derivative compound. Generally, the crosslinking agent is an individual compound or mixture of compounds selected from the group consisting of: melamine formaldehyde resins, glycoluril formaldehyde resins, polycarboxylic acids and anhydrides, polyamines, epihalohydrins, diepoxides, dialdehydes, diols, carboxylic acid halides, ketenes, aziridines, carbodiimides, and isocyanates.

In another aspect of the present invention, the conductive thermal image receiver element may comprise a support and have on one or both opposing sides of the support: has a T of at least 35 ℃ and up to and including 60 ℃_gThe dry image receiving layer of (a), the dry image receiving layer being an outermost layer of the thermal image receiver element, having a dry thickness of at least 1 μ ι η and up to and including 3 μ ι η, and comprising a water-dispersible release agent, a cross-linking agent, a water-dispersible conductive polymeric material, and a polymeric binder matrix consisting essentially of: (1) a water-dispersible acrylic polymer comprising chemically reacted or chemically non-reacted carboxyl or formate groups, wherein the water-dispersible acrylic polymer comprises repeating units derived from: (a) one or more ethylenically unsaturated polymerizable acrylates or methacrylates comprising an alkyl acrylate, cycloalkyl ester, or aryl ester group having at least 4 carbon atoms, (b) one or more carboxyl-containing or carboxylate-containing ethylenically unsaturated polymerizable acrylates or methacrylates, and (c) optionally styrene or a styrene derivative, wherein (a) the recurring units represent at least 20 mol% and up to and including 99 mol% of the total recurring units, and (b) the recurring units represent at least 1 mol% and up to and including 10 mol%, and (2) a T having a temperature of at least 0 ℃ and up to and including 20 ℃, (b) a polymer having a molecular weight of at least 0 ℃ and up to and including 20 ℃, (c) a polymer having a molecular weight of at least one or more monomers_gA water-dispersible film-forming polyester having water-dispersible groups, wherein the water-dispersible acrylic polymer is receptive to the total dry imageIs present in an amount of at least 60 wt% and up to and including 90 wt% of the weight of the layer, and is present in the polymer binder matrix at a dry ratio to the water dispersible polyester of at least 4:1 and up to and including 20: 1.

Another variation of the invention provides a thermal image receiver element comprising a support and having on at least one side of the support: a dry image receiving layer as an outermost layer of the thermal image receiver element, the dry image receiving layer having a T of at least 25 ℃ and up to and including 70 ℃_gAt least 0.5 μm and up to and including a dry thickness of 5 μm, the dry image-receiving layer comprising a water-dispersible release agent, a cross-linking agent, a water-dispersible conductive polymeric material, and a polymeric binder matrix consisting essentially of: (1) one or more water-dispersible acrylic polymers derived from one or more ethylenically unsaturated polymerizable monomers; and (2) has a T of 30 ℃ or less than 30 ℃_gWherein the one or more water-dispersible acrylic polymers are present in an amount of at least 55 weight% and up to and including 90 weight%, based on the total dry image receiving layer weight; one or more water-dispersible acrylic polymers are present in the polymer binder matrix at a dry ratio to the water-dispersible polyester of at least 1:1 up to and including 20: 1; and the water-dispersible release agent is present in an amount of at least 0.5 wt% and up to and including 10 wt%, based on the total weight of the dried image receiving layer.

Also disclosed are imaging assemblies comprising a thermal image receiver element according to any of the specifications described herein, wherein the thermal image receiver element is placed in thermal association with a thermal donor element.

Another aspect of the present invention is a method of making a conductive thermal image receiver element described herein. The method comprises the following steps: (A) applying an aqueous image-receiving layer formulation to one or both opposing sides of a support, the aqueous image-receiving layer formulation comprising a water-dispersible release agent, a cross-linking agent, a water-dispersible conductive polymeric material, and a polymer binder composition consisting essentially of: (1) containing chemically reactive or chemically non-reactive hydroxy, phosphinesA water-dispersible acrylic polymer of an acid group, a phosphonate group, a sulfonic acid group, a sulfonate group, a carboxyl group, or a carboxylate group, and (2) a polymer having a T of 30 ℃ or less than 30 ℃_gWherein the water-dispersible acrylic polymer is present in an amount of at least 55% by weight of the total dry image receiving layer weight obtained and is present in the polymeric binder matrix at a dry ratio to the water-dispersible polyester of at least 1:1 to and including 20: 1; and (B) drying the aqueous image-receiving layer formulation to form a dried image-receiving layer on one or both opposing sides of the support. According to the method, the aqueous image receiving layer formulation may additionally be heat treated at a temperature of at least 70 ℃. The method may further comprise the step of applying the aqueous image receiving layer formulation to a support and drying it to give a dried image receiving layer in a predetermined pattern.

The related method for printing comprises the following steps: image-wise transferring the transparent polymeric film, the one or more dye images, or both the transparent polymeric film and the one or more dye images from the thermal donor element to the image-receiving layer of any of the dry conductive thermal image receiving elements described herein.

In a variation of the invention, the conductive thermal image receiving element may comprise a support and have on at least one side of the support: an electrically conductive layer comprising an outermost layer, wherein the outermost layer is an aqueous coatable dye-receiving layer having a thickness in the range of 1.0 μ ι η to 1.2 μ ι η and wherein the aqueous dye-receiving layer comprises a water-dispersible release agent, a crosslinker, and a polymeric binder matrix consisting essentially of: (1) a water-dispersible acrylic polymer comprising chemically reacted or chemically non-reacted hydroxyl, phosphonate, sulfonate, carboxyl, or carboxylate groups; (2) having a T of 30 ℃ or less than 30 DEG C_gThe water-dispersible polyester of (1); wherein the water-dispersible acrylic polymer is present in an amount of at least 55 wt% of the total aqueous coatable dye-receiving layer weight and is present in a dry ratio to the water-dispersible polyester of at least 1: 1; and (3) a receiver overcoat layer comprising a water-dispersible conductive polymeric material.

The thickness of the receiver overcoat layer is from 0.1 μm to 0.62 μm, from 0.10 μm to 0.8 μm, or 0.29 μmTo the range of 0.62 μm. Further, the water-dispersible conductive polymeric material can be present in the receiver overcoat layer in an amount greater than or equal to 1.0 wt%, or in a range from 1.0 wt% to 3.0 wt%, or from 1.2 wt% to 3.0 wt% of the total dry weight of the receiver overcoat layer. In other words, the water dispersible conductive polymeric material may be greater than 10.76mg/cm³Is present in the receiver overcoat layer.

Another aspect of the present invention is a method of making a conductive thermal image receiver element described herein. The method may comprise the steps of: (A) applying an aqueous coatable dye-receiving layer formulation to one or both opposing sides of a support, the aqueous coatable dye-receiving layer formulation comprising a water-dispersible release agent, a crosslinking agent, and a polymeric binder composition consisting essentially of: (1) a water-dispersible acrylic polymer comprising chemically reacted or chemically non-reacted hydroxyl, phosphonate, sulfonate, carboxyl, or carboxylate groups, and (2) a polymer having a T of 30 ℃ or less than 30 ℃_gThe water-dispersible polyester of (1); wherein the water-dispersible acrylic polymer is present in an amount of at least 55% by weight of the total resulting dry image receiving layer weight and is present in the polymeric binder matrix at a dry ratio to the water-dispersible polyester of at least 1:1 to and including 9.2:1, or at least 4:1 to and including 20: 1; (C) drying the aqueous image receiving layer formulation to form a dried image receiving layer on one or both opposing sides of the support; (D) applying a receiver overcoat layer comprising an electrically conductive polymeric material onto at least one side of a support coated with an aqueous coatable dye-receiving layer, (E) drying the aqueous image-receiving layer formulation to form a dried image-receiving layer on one or both opposing sides of the support.

According to such methods, the aqueous coatable dye-receiving layer formulation is heat treated at a temperature of at least 70 ℃. In addition, an aqueous coatable dye-receiving layer formulation is coated onto a support and dried to give a dry image-receiving layer in a predetermined pattern. The same aqueous coatable dye-receiving layer formulation may be applied to both opposing sides of the support.

The invention features a conductive polymeric material included in an outermost layer of a thermal image receiver element. The present invention provides a water dispersible conductive polymeric material comprising poly (3, 4-ethylenedioxythiophene) -poly (styrenesulfonate). Alternatively, the water-dispersible conductive polymeric material can consist essentially of poly (3, 4-ethylenedioxythiophene) -poly (styrenesulfonate) and a polar solvent.

It is another feature of the present invention to include additional surfactants and/or dispersants in the receiver overcoat layer. That is, the present invention provides a conductive thermal image receiver element comprising an aqueous coatable dye-receiving layer and a receiver overcoat layer, wherein the receiver overcoat layer comprises a water-dispersible conductive polymeric material and a surfactant. Typically, the surfactant is present in the receiver overcoat layer in an amount of about 2.5 wt%, or in an amount ranging from 1 to 5 wt%. In addition to, or in place of, the surfactant, one or more dispersants may also be included in the receiver overcoat layer. Suitable dispersants are: a random copolymer comprising benzyl methacrylate and methacrylic acid, a random terpolymer of benzyl methacrylate, stearyl methacrylate, and methacrylic acid, and an acrylic block copolymer or terpolymer. In certain variations of the invention, the surfactant is present in the receiver overcoat layer at about 1 to 4 weight percent, or more specifically about 2 weight percent. One or more dispersants may also be present in the receiver overcoat layer with or without a surfactant. The one or more dispersants are present in the receiver overcoat layer at about 0.5 to 6 wt% (with respect to the total of all dispersants included in the receiver overcoat layer), or more specifically, about 1 wt% to 3 wt%, based on the total dry weight of the receiver overcoat layer.

According to the present invention, the conductive thermal image receiver element may alternatively include a support and have on at least one side of the support: an electrically conductive layer comprising an outermost layer, wherein the outermost layer is an aqueous coatable dye-receiving layer having a thickness ranging from 0.1 μ ι η to 5 μ ι η, and wherein the aqueous dye-receiving layer comprises a water-dispersible release agent, a crosslinker, and a polymeric binder matrix consisting essentially of: (1) containing chemically reactive or chemically non-reactive hydroxyl groups,A water-dispersible acrylic polymer of phosphonic, sulfonic, carboxylic, or carboxylic ester groups, wherein the water-dispersible acrylic polymer comprises more than 1% excess surfactant used to prepare the acrylic polymer; (2) having a T of 30 ℃ or less than 30 DEG C_gThe water-dispersible polyester of (a), wherein the water-dispersible acrylic polymer is present in an amount of at least 55% by weight of the total aqueous coatable dye-receiving layer weight and is present in a dry ratio to the water-dispersible polyester of at least 1: 1; and (3) a water-dispersible conductive polymer material.

In one variation, the conductive thermal image receiver element may include a support and have on at least one side of the support: an electrically conductive layer comprising an outermost layer, wherein the outermost layer is an aqueous coatable dye-receiving layer having a thickness ranging from 0.1 μ ι η to 5 μ ι η, and wherein the aqueous dye-receiving layer comprises a water-dispersible release agent, a crosslinker, and a polymeric binder matrix consisting essentially of: (1) a water-dispersible acrylic polymer comprising chemically reacted or chemically non-reacted hydroxyl, phosphonate, sulfonate, carboxyl, or carboxylate groups, wherein the water-dispersible acrylic polymer comprises more than 1% excess surfactant used to prepare the acrylic polymer; (2) having a T of 30 ℃ or less than 30 DEG C_gThe water-dispersible polyester of (a), wherein the water-dispersible acrylic polymer is present in an amount of at least 55% by weight of the total aqueous coatable dye-receiving layer weight and is present in a dry ratio to the water-dispersible polyester of at least 1: 1; and (3) a receiver overcoat layer comprising a water-dispersible conductive polymeric material. The excess surfactant may be present in an amount of about 1% to 5% by weight.

It is another feature of the present invention to include one or more defoaming agents in the dye-receiving layer of the thermal image receiver element. For example, embodiments provide a conductive thermal image receiver element having a dye-receiving layer as described throughout this disclosure, wherein the dye-receiving layer comprises a surfactant and an antifoaming agent. The defoaming agent may be selected from the group consisting of: air products (Air)) Dinol 607 and YingchuangThe Degafumace (TEGO FOAMEX)800, the Yingchu Degafumace 805, the Yingchu Degafumace 825, and the MitigoSiervite (SILWET) L-7200, Siervite L-7210 of Meiji, Siervite L-7220 of Meiji, Siervite L-7607 of Meiji, and Dow Corning (Dow)) Dow Corning 6 additive, Dow Corning 62 additive, Xiameter (XIAME ETER) AFE-1430, Sirtech's Siltech's Sirte C-4830, Airas of air products (AIRASE)5300, Airas of air products 5500, and Airas of air products 5700. Generally, the defoamer is present in an amount of 0.01 to 0.32 wt% based on the total dry weight of the dye-receiving layer.

In other words, the dye-receiving layer comprising the anti-foaming agent is derived from an aqueous polymer emulsion. Such aqueous polymer emulsions yield a foam height of less than or equal to 3.5cm above the initial liquid level after mixing the aqueous polymer emulsion at 2000rpm for two minutes. More specifically, the aqueous polymer emulsion produced a foam height of 0cm above the initial liquid level after mixing the aqueous polymer emulsion at 2000rpm for two minutes and waiting for another minute.

The invention will be described in more detail with particular reference to certain embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Drawings

Fig. 1A and 1B provide schematic overview diagrams of two different thermal image receiving elements. Fig. 1A illustrates an embodiment in which the aqueous coatable dye-receiving layer ("DRL") (layer (1)) having a conductive polymeric material is the outermost (or top) layer. Fig. 1B illustrates an embodiment in which the aqueous receiver overcoat ("ROC") (layer (1a)) is the outermost (or top) layer and is on top of the aqueous coatable DRL (layer (1B)).

Fig. 2 provides results of a study of a thermal image receiver element comprising a single layer of an aqueous coatable dye-receiving layer (similar to the one shown in fig. 1A), wherein the DRL comprises a polymeric binder matrix consisting essentially of a water-dispersible acrylic polymer, a water-dispersible polyester, and a water-dispersible conductive polymeric material.

Fig. 3 provides results of a study of a thermal image receiver element comprising a bi-layer aqueous coatable dye-receiving layer (similar to the one shown in fig. 1B), wherein the bi-layer DRL comprises a polymeric binder matrix consisting essentially of a water-dispersible acrylic polymer, a water-dispersible polyester, and a receiver overcoat layer subsequently comprising a water-dispersible conductive polymeric material.

Fig. 4 provides a table showing the results of various experiments in which surfactants were added to the receiver overcoat layer of the bilayer DRL. When no surfactant is added, there is an undesirable amount of misregistration. However, when additional surfactant is added at about 2.5 wt%, the number of misregistrations is reduced to none, or an acceptable minimum number.

Fig. 5 provides a table showing the results of various experiments in which the surfactant was added in a 1% excess relative to that typically used to make acrylic polymers. When no excess surfactant is added, undesirable misregistration occurs. However, when the surfactant is added at about 2% by weight (or 1% excess) or more, misregistration error is reduced to an acceptable level.

Figure 6 provides a table showing the results of employing an antifoaming agent in various dispersions of aqueous DRL formulations. As can be seen, the addition of a defoamer to the aqueous dispersion can significantly reduce the foam height.

Figure 7 provides a table showing various defoamers tested in dispersions of aqueous DRL formulations and the effect such defoamers have on the actual foam height above the aqueous system after mixing.

Fig. 8 provides a table detailing the results of filterability tests for various dispersions of aqueous ROC formulations.

Detailed Description

Unless otherwise indicated, when the singular forms "a", "an" and "the" are used herein to define the various components of the compositions, formulations and layers described herein, it is intended to include one or more of the components (i.e., including the plural referents).

The use of numerical values in the various ranges specified herein is considered approximate, as if the minimum and maximum values within the ranges were all preceded by the word "about," unless expressly specified otherwise. In this way, minor variables above and below the range can be used to achieve substantially the same results as values within the range. In addition, the disclosure of these ranges is intended as a continuous range including every value between the minimum and maximum values.

Unless otherwise indicated, the terms "thermal image receiver element" and "receiver element" are used interchangeably to refer to features of the invention.

The term "duplex" is used to refer to embodiments of the invention in which each of the opposite sides of a substrate (defined below) has a dry image-receiving layer (defined below) and thus each side is capable of forming a thermal image (transparent polymeric film or dye image), although it is not necessary in the methods of the invention that the thermal images be formed on both sides of the substrate at all times. "Duplex" elements may also be referred to as "double-sided" elements.

The glass transition temperature (T) can be determined using Differential Scanning Calorimetry (DSC) and known procedures such as monitoring different power inputs for sample compositions_g) And are referenced as they are all heated at a constant rate and maintained at the same temperature. The differential power input can be plotted as a function of temperature and the temperature at which the curve steeply varies in latitude is generally specified as T for the sample polymer or dry image receiving layer composition_g。

Unless otherwise indicated, the% solids or weight% is stated with reference to the total dry weight of the particular composition or the particular composition of the particular layer.

The term "thermal donor element" is used to refer to various thermal donor elements (defined below) that can be used to thermally transfer dyes, inks, clear films, or metals, and do not necessarily transfer only dyes or inks.

The term "thermal bonding" is used to refer to two different elements that are placed in a relationship that allows for thermal transfer of a dye, metal, or thinner polymer film. This relationship generally requires intimate physical contact of the two elements as they are heated.

The term "aqueous coating" is used to refer to a layer that is coated or coated with an aqueous coating formulation.

The term "aqueous coatable" is used to refer to a layer that is coated or coated in an aqueous coating formulation but can then be dried to become a dried layer.

Unless otherwise indicated, the terms "polymer" and "resin" mean the same thing. Unless otherwise indicated, the term "acrylic polymer" is meant to encompass homopolymers having the same repeating units along the organic backbone as well as copolymers having two or more different repeating units along the backbone.

The term "ethylenically unsaturated polymerizable monomer" refers to an organic compound having one or more ethylenically unsaturated polymerizable groups (e.g., vinyl groups) that can be polymerized to provide an organic backbone of carbon atoms and optionally a variety of side chains attached to the organic backbone. The polymerization product of a specific ethylenically unsaturated polymerizable monomer within the organic backbone is referred to as a "repeat unit". The multiple repeating units in the water-dispersible acrylic polymers used in the practice of the present invention are distributed in a random fashion along the backbone of a given polymer, and although blocks of common repeating units may be found they are not intentionally formed along the organic backbone.

The terms "water-dispersible" and "water-dispersible" when used to describe any of the acrylic polymers, polyesters, release agents, or any other component mentioned herein, mean that these materials are generally dispersed in an aqueous medium during their manufacture or coating onto a support. The term generally refers to the concept of supplying and using a particular material in the form of an aqueous dispersion. Components described as "water dispersible" may not be soluble in an aqueous medium and may not readily settle within an aqueous medium. These terms do not mean that the components are redispersible in aqueous media when coated and dried. Conversely, when a "water-dispersible" component is dried on a support, it generally remains unchanged upon contact with water or an aqueous solution.

The term "antistatic agent" means a water dispersible conductive polymeric material (as described in more detail below).

Thermal image receiver element

Embodiments of the thermal image receiver elements disclosed herein include an outermost image-receiving layer on one or both (opposing) sides of a support (described below). In the single layer DRL embodiment (fig. 1A), the DRL is the outermost layer so that transfer of dye, transparent film or metal can occur. In the embodiment shown in FIG. 1B, the outermost layer is a double layer DRL/ROC combination. The ROC is on top of the DRL. In the two-layer embodiment, both the ROC and the DRL accept transfer of a dye, a transparent film, or a metal donor material. In single layer as well as bilayer embodiments, one or more additional layers (described below) may be located between the dye image-receiving layer and the support. Furthermore, in both monolayer and bilayer embodiments, the DRL and ROC layers are formed as an aqueous dispersion coated on one or both sides of the support. The components of such aqueous dispersions for the DRL and ROC layers are described below.

Aqueous coatable dye-receiving layer

The dry image receiving layer (also referred to herein as an aqueous coatable dye receiving layer or sometimes as an image receiving layer or, more simply, as a DRL) is the outermost layer in a single layer thermal image receiver element embodiment and the second outermost layer in a dual layer thermal image receiver element embodiment (in which the ROC is on top of the DRL). DRLs typically have a T of at least 25 ℃ and up to and including 70 ℃, or typically at least 35 ℃ and up to and including 70 ℃, or at least 35 ℃ and up to and including 60 ℃_g. Preferably, T_gIs 30 ℃ or less than 30 ℃. Drying image-receiving layer T_gMeasured as described above by evaluating a dried image receiving layer formulation containing a polymeric binder matrix comprising one or more of the following components using a Differential Scanning Calorimeter (DSC): (1) water-dispersible acrylic polymer, (2) water-dispersible polyesterAnd (3) a water-dispersible conductive polymer material.

The aqueous coatable dye-receiving layer has a dry thickness of at least 0.1 μm and up to and including 5 μm, and typically at least 0.5 μm and up to and including 3 μm. In certain embodiments, the aqueous coatable dye-receiving layer has a dry thickness of 1.2 μm to 1.5 μm, while in other embodiments, the DRL has a dry thickness of 0.7 μm to 1 μm. This dry thickness is an average value measured in at least 10 places in a suitable electron scanning micrograph or other suitable means and it is possible that there may be some places in the layer that exceed the mentioned average dry thickness.

The aqueous coatable dye-receiving layer comprises a polymeric binder matrix consisting essentially of: (1) a water-dispersible acrylic polymer and (2) a water-dispersible polyester. In single layer DRL embodiments, a water-dispersible conductive polymeric material (also referred to herein as a conductive polymer or antistatic agent) can additionally be included in the DRL.

Polymer adhesive matrix component- (1) Water-dispersible acrylic Polymer

With respect to one or more water-dispersible acrylic polymers in the polymeric binder matrix of the aqueous DRL, each comprises chemically reacted or chemically non-reacted hydroxyl, phosphonate, sulfonic, sulfonate, carboxyl, or carboxylate groups, and specifically, chemically reacted or chemically non-reacted carboxyl or carboxylate groups. The term water-dispersible acrylic polymer includes styrene acrylic copolymers. For example, the water-dispersible acrylic polymer may be crosslinked by hydroxyl or carboxyl groups (typically after the image-receiving layer formulation has been applied to the support) to provide amine ester, urethane, amide, or urea groups. Mixtures of these water-dispersible acrylic polymers having the same or different reactive groups can be used if desired.

May be selected from the group consisting of_gCrosslinkable, resistance to discoloration of transfer printed materials, and heat transferability) of one or more ethylenically unsaturated polymerizable monomers. In general, suitable water-dispersibilityThe acrylic polymer comprises repeat units derived primarily (greater than 50 mol%) from one or more ethylenically unsaturated polymerizable monomers that provide the desired characteristics. The remainder of the repeating units may be derived from different ethylenically unsaturated polymerizable monomers.

For example, the water-dispersible acrylic polymer comprises repeating units derived from a combination of: (a) one or more ethylenically unsaturated polymerizable acrylates or methacrylates comprising acyclic alkyl ester, cycloalkyl ester, or aryl ester groups; (b) one or more carboxyl-or sulfonic acid group-containing ethylenically unsaturated polymerizable acrylates or methacrylates, and (c) optionally styrene or a styrene derivative.

The acyclic alkyl, cycloalkyl or aryl ester group may be substituted or unsubstituted, and it may have up to and including 14 carbon atoms. The acyclic alkyl ester group comprises straight and branched, substituted or unsubstituted alkyl groups, including aryl-substituted alkyl groups and aryloxy-substituted alkyl groups, and may have at least 1 carbon atom and up to and including 22 carbon atoms. The cycloalkyl ester group typically has at least 5 carbon atoms and up to and including 10 carbon atoms in the ring, and can be a substituted or substituted cyclic ester group including an alkyl-substituted cyclic ester ring. Suitable aryl ester groups include phenyl and naphthyl ester groups, which may be substituted or unsubstituted with one or more groups on the aromatic ring.

(a) Representative examples of ethylenically unsaturated polymerizable acrylates or methacrylates include (but are not limited to): n-butyl acrylate, n-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, benzyl acrylate, benzyl methacrylate, phenoxyethyl 2-acrylate, stearyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl methacrylate, chloroethyl 2-acrylate, benzyl 2-propyl acrylate, n-butyl 2-bromoacrylate, phenoxyacrylate, and phenoxymethacrylate. Particularly useful (a) ethylenically unsaturated polymerizable acrylates and methacrylates include benzyl acrylate, benzyl methacrylate, t-butyl acrylate, and phenoxyethyl 2-acrylate.

Representative (b) hydroxyl-, phosphonic-, carboxyl-or sulfonic-group-containing ethylenically unsaturated polymerizable acrylates and methacrylates include, but are not limited to: acrylic acid, sodium salt, methacrylic acid, potassium salt, 2-acrylamido-2-methylpropanesulfonic acid, sodium salt, sulfoethyl 2-methacrylate, sodium salt, sulfopropyl 3-methacrylate, sodium salt, and the like. Acrylic and methacrylic acid or salts thereof are particularly useful such that the water-dispersible acrylic polymer contains chemically reacted or chemically non-reacted carboxyl or carboxylate groups.

(c) Ethylenically unsaturated polymerizable monomers include (but are not limited to): styrene, alpha-methylstyrene, 4-acetoxystyrene, 2-bromostyrene, alpha-bromostyrene, 2, 4-dimethylstyrene, 4-ethoxystyrene, 3-trifluoromethylstyrene, 4-vinylbenzoic acid, vinylbenzyl chloride, vinylbenzyl acetate and vinyltoluene. Styrene is particularly suitable.

In these water-dispersible acrylic polymers, (a) recurring units generally represent at least 20 mol% and up to and including 99 mol% of the total recurring units, or more typically at least 30 mol% and up to and including 98 mol% of the total recurring units in the polymer.

(b) The recurring units generally represent at least 1 mol% and up to and including 10 mol%, and typically at least 2 mol% and up to and including 5 mol%, of the total recurring units in the polymer.

In some embodiments, it is desirable to have a relatively low amount of pendant acid groups in the water-dispersible acrylic polymer such that the repeating units derived from (a) repeating units comprise at least 1 mol% and up to and including 3 mol% based on the total repeating units in the polymer.

When the (c) ethylenically polymerizable monomers are used to prepare the water-dispersible acrylic polymer, the repeating units derived from those monomers are generally present in an amount of at least 30 mol% and up to and including 80 mol%, or typically at least 50 mol% and up to and including 70 mol%, of the total repeating units in the polymer.

The water-dispersible acrylic polymers used in the practice of the present invention can makePrepared using readily available reactants and known addition polymerization conditions and free radical initiators. The preparation of some representative copolymers for use in the present invention is provided below and in tables I and II. For example, some suitable water-dispersible acrylic polymers are available from rattan canes (Fujikura) (japan), DSM, and Eastman Kodak Company. Generally, the water-dispersible acrylic polymer is provided in the form of an aqueous dispersion. Suitable water-dispersible acrylic polymers also typically have a number average molecular weight (M) of at least 5,000 and up to and including 1,000,000 as measured using size exclusion chromatography_n). Suitable water-dispersible acrylic polymers include, but are not limited to, NeoCryl^TM A-6092、NeoCryl^TM XK-22-、NeoCryl^TM6092 and NeoCryl^TM 6015、AVANSE MV-100、AVANSE 200、RHOPLEX^TMAcrylic acid product series, such as Phoplex 585, HG-706, VSR-50, Z-Clean 1500, Lubrizol Carboset and Carbotac acrylic acid product series,ENCOR all acrylic emulsions and SNAP acrylic polymers such as SNAP 720 and 728, and the like. In certain embodiments, a mixture of polymers is used (see below). Sometimes, the water-dispersible acrylic polymer is referred to herein as an "acrylic latex" or an "acrylic polymer latex".

In some embodiments, the thermal image receiver element comprises a water-dispersible acrylic polymer comprising repeat units derived from: (a) one or more ethylenically unsaturated polymerizable acrylates or methacrylates comprising acyclic alkyl, cycloalkyl, or aryl ester groups having at least 4 carbon atoms, (b) one or more carboxyl-or sulfonic acid group-containing ethylenically unsaturated polymerizable acrylates or methacrylates, and (c) optionally styrene or a styrene derivative, and wherein (a) the recurring units constitute at least 10 mol% and up to and including 99 mol% of the total recurring units, and (b) the recurring units constitute at least 1 mol% and up to and including 10 mol%.

For example, the water-dispersible acrylic polymer in the dry image-receiving layer can be crosslinked through hydroxyl or carboxyl groups using a suitable crosslinking agent (described below) to provide amino ester, urethane, amide, or urea groups.

The one or more water-dispersible acrylic polymers are present in an amount of at least 55 wt%, and typically at least 60 wt% and up to and including 80 wt% or 90 wt%, based on the total dry image receiving layer weight.

Polymer adhesive matrix component- (2) Water-dispersible polyester

Each of the one or more water-dispersible polyesters present in the polymeric binder matrix has a T of 30 ℃ or less_gOr typically at least-10 ℃ and up to and including 30 ℃, or even at least 0 ℃ and up to and including 20 ℃ T_g. Preferably, the water-dispersible polyester has a T of 30 ℃ or less_g. Generally, water-dispersible polyesters are film-forming polymers that provide a substantially uniform film when dry-like coated. Such polyesters may contain some water-dispersing groups (e.g., sulfonic acid groups, sulfonate groups, carboxyl groups, or carboxylate groups) to enhance water dispersibility. Mixtures of these water-dispersible polyesters may be used together. Suitable water-dispersible polyesters can be prepared by reaction with suitable diols using known diacids. In many embodiments, the diol is an aliphatic diol and the diacid is an aromatic diacid, such as phthalate, isophthalate, and terephthalate, in suitable molar ratios. The mixture of diacids can be reacted with the mixture of diols. Either or both of the diacid or diol may contain suitable sulfonic or carboxylic groups to improve water dispersibility. Commercial sources of suitable water-dispersible polyesters are described in the examples below. Two suitable water dispersible polyesters are copolyesters of isophthalate and diethylene glycol and copolymers formed from isophthalate and terephthalate esters and mixtures of ethylene glycol and neopentyl glycol. Exemplary polyesters are those available fromIs/are as followsMD-1480. Other water-dispersible copolyesters are also available fromIs/are as followsMD-1400, MD-1335, MD-1930, MD-1985, and the like, and Istman AQ 1350, AQ 1395, AQ 2350, Eastek 1400, and the like, available from Istman.

Suitable water dispersible polyesters for use in the present invention may be, for example, ToyoSome commercial sources of (japan) and eastman chemical company, and can also be readily prepared using known starting materials and condensation polymerization conditions.

Additionally, one or more water-dispersible acrylic polymers are present in the polymer binder matrix at a dry ratio to water-dispersible polyester of at least 1:1, or typically at least 1:1 up to and including 6:1, or more likely at least 1.5:1 up to and including 4: 1. Preferably, the one or more water-dispersible acrylic polymers are present in the polymeric binder matrix at a dry ratio to the water-dispersible polyester of at least 1:1 up to and including 9.2: 1. In certain embodiments, the one or more water-dispersible acrylic polymers are present in the polymeric binder matrix at a dry ratio to the water-dispersible polyester of at least 1:1, or at least 4:1 and up to and including 20:1, or at least 1:1 up to and including 20:1, or at least 4:1 up to and including 15: 1.

Aqueous coatable receiver overcoat

The receiver overcoat layer is the outermost layer in the two-layer thermal image receiver element embodiment. This layer is not present in the single layer DRL embodiment. The aqueous coatable receiver overcoat layer has a dry thickness of at least 0.1 μm and up to and including 5.0 μm, and typically at least 0.2 μm and up to and including 1.0 μm. In certain embodiments, the aqueous coatable receiver overcoat has a dry thickness of 0.2 μm to 0.4 μm, while in other embodiments, the ROC has a dry thickness of 0.4 μm to 0.7 μm, or about 0.62 μm. According to the bilayer DRL/ROC example (FIG. 1B), the combined thickness of the aqueous coatable ROC and the aqueous coatable DRL is about 0.8 μm to 2.0 μm, or more specifically 1.0 μm to 1.2 μm.

The aqueous coatable receiver overcoat formulation comprises a polymeric adhesive matrix composition consisting essentially of: (1) a water-dispersible acrylic polymer and (2) a water-dispersible polyester described in all the same respects with reference to DRL. Thus, the foregoing discussion of the polymer binder matrix component with respect to ROC is incorporated herein by reference. The ROC further comprises a water-dispersible conductive polymeric material component (described below), as well as additional surfactants and optional adjuncts, such as surfactants for emulsification of the water-dispersible acrylic polymer, one or more release agents, one or more crosslinking agents, and any other adjunct described herein. The weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 6:1, or typically at least 1.5:1 to and including 5: 1. Preferably, the weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 9.2: 1. In certain embodiments, the one or more water-dispersible acrylic polymers are present in the polymeric binder matrix at a dry ratio to water-dispersible polyester of at least 1:1, or typically at least 4:1 and up to and including 20:1, or more likely at least 1:1 and up to and including 20:1, or even at least 4:1 and up to and including 15: 1.

Water-dispersible conductive polymeric materials

In a single layer DRL embodiment, a water dispersible conductive polymeric material is present in the DRL. In the dual layer ROC/DRL embodiment, the water dispersible conductive polymeric material is added only to the ROC. Exemplary water dispersible conductive polymeric materials include thiophenes such as poly (3, 4-ethylenedioxythiophene) -poly (styrenesulfonate), known as PEDOT or PEDT.P andp is a commercially available PEDOT solution which is a 1.3% aqueous solution of the conjugated polymer PEDOT: PSS. PSS stands for poly (styrene sulfonate).

The PEDOT: PSS conjugate is mixed with an alcohol (such as diethylene glycol) or any other polar solvent, which enhances the conductivity of the conjugated PEDOT: PSS polymer. PSS is a conjugated polymer that carries a positive charge and is still optically transparent. The multilayer conductive thermal image receiver elements of the present invention provide excellent electrical conductivity to enable efficient and effective dissipation of electrostatic charges typically generated during media transport and image formation processes. This static charge accumulation causes undesirable print defects such as white dropout and cockling on the actual printed image. The present invention eliminates static charge buildup, resulting in better print quality and improved stacking and processing of print images.

Another benefit of the present invention is that it can be used with all printers and thus can be considered a universal printer media that can be used with many types of printers, including thermal printers.

The water-dispersible conductive polymeric material may be present in the DRL (single layer embodiment) or ROC (double layer embodiment) in an amount ranging from 0.5 to 3.0 mass%, or more specifically, from 1.0 to 2.0 mass% or from 1.5 to 2.5 mass%, based on the dry mass of the respective layer to which the conductive polymer is added. As previously mentioned, in certain embodiments, water-dispersible conductive polymeric materials are added to the dye-receiving layer, while in other embodiments, such materials are added to the receiver overcoat layer. For example, referring to fig. 1B, a conductive polymeric material may be added to the ROC layer and not to the DRL layer. In practice, the ROC and DRL layers shown in fig. 1B are coated almost simultaneously. Thus, the material in the ROC is immersed in the DRL, including the conductive polymeric material. Specifically, referring to the bilayer embodiment (fig. 1B), the water-dispersible conductive polymeric material may be present in the receiver overcoat layer in an amount equal to or greater than 1 dry mass%, or alternatively, in an amount equal to or greater than 1.4 dry mass%. In certain other embodiments, the conductive polymeric material may also be present in the receiver overcoat layer in an amount in the range of 1.2% to 3%, or in the range of 1% to 3%. In other embodimentsWherein the water-dispersible conductive polymeric material is present at greater than or equal to 10.76mg/cm³Is present in the ROC.

Fig. 2 provides an exemplary polymeric adhesive matrix composition in which a water-dispersible conductive polymeric material is present within an aqueous coatable dye-receiving layer for a single layer DRL embodiment-i.e., none of the samples in fig. 2 have a ROC layer. C1-C6 represent control samples, while E1-E2 represent examples according to the invention. For comparative examples C1-C4, the conductive polymeric material was added to the sublayer and not to the DRL. While all four samples did not exhibit buckling and wrinkling, all samples except C1 suffered from image bleeding. Image bleeding was measured after one week under variable conditions: 35 ℃/50% relative humidity; 40 ℃/50% relative humidity; and 50 deg.C/50% relative humidity. Control sample C1 did not suffer from buckling/wrinkling or image bleeding. However, to achieve such results, the thickness of the DRL needs to be significantly increased. Control examples C5 and C6 did not include any conductive polymeric material in the DRL and both test samples produced undesirable buckling and wrinkling. For inventive examples E1 and E2, conductive polymeric material was added to the DRL as opposed to being added to the sublayer. Neither E1 nor E2 exhibited buckling, wrinkling, and image bleeding. However, the DRL thickness remains at 1.4 μm and requires a significantly smaller amount of conductive material. Thus, by adding a conductive polymeric material to the DRL, the inventors are able to avoid unwanted buckling, wrinkling, and image bleeding without having to sacrifice the thinness of the DRL and without having to add large amounts of conductive material. The surface resistance ("SER") of each sample was also tested. During printing, it is advantageous to maintain a low surface resistivity to dissipate static electricity. As can be seen in fig. 2, the addition of conductive polymeric material to the DRL helps achieve this desired result.

Fig. 3 provides an exemplary polymeric binder matrix composition in which a water-dispersible conductive polymeric material has been added to a receiver overcoat layer, which is placed over an aqueous coatable dye-receiving layer (for a dual layer ROC/DRL structure). C8-C13 represent control samples, while E3-E9 represent examples according to the invention. As with the samples tested in fig. 2, the samples detailed in fig. 3 were observed for surface resistance, buckling/wrinkling effects, and effects on image quality. For all samples (C8-C13 and E3-E9), a conductive polymeric material was added to the ROC. As can be seen in samples C8-C13 in fig. 3, buckling, wrinkling and susceptibility to spotting are observed when the conductive material is added in an amount of 1.2% or less than 1.2% by dry mass. By increasing the amount of conductive polymeric material in the ROC to greater than 1.2%, the desired results-i.e., no buckling, no wrinkling, and no susceptibility to white bleed or spotting-are achieved.

The polymeric binder matrix forms the primary structure of the dye-receiving layer and the receiver overcoat layer and is substantially free of other polymers other than (1) the water-dispersible acrylic polymer and (2) the water-dispersible polyester and (3) the water-dispersible conductive polymeric material described above. However, minor amounts (typically, less than 10% by weight of the total dry weight of the corresponding layer) of one or more other polymers or components can be added to the aqueous ROC and DRL dispersion to achieve other desired results. For example, such additional components may include conductive polymeric materials (previously described), as well as cross-linkers, release agents, additional surfactants, and dispersants (discussed more fully below).

Other component-Water-dispersible Release agent

In some embodiments, the aqueous coatable dye-receiving layer and/or receiver overcoat layer comprises one or more water-dispersible release agents that can reduce stiction that occurs between the thermal donor element and the thermal image receiver element of the present invention during thermal imaging. These compounds are generally not water soluble, but are water dispersible such that they are uniformly dispersed within the aqueous image receiving layer formulation (described above). The release agent may also help provide a uniform film in the dried image receiving layer during formulation and drying. These compounds may be polymeric or non-polymeric, but are generally polymeric. Such compounds are generally not redispersible when coated and dried in an aqueous coatable dye-receiving layer.

Suitable water-dispersible release agents include (but are not limited to): water dispersible fluorine-based surfactant, silicone-based surfactant, modified silicone oil (e.g., epoxy-modified, carboxyl-modified, amino-modified, alcohol-modified, fluorine-modified, alkylaryl-alkyl-modified, and related applications)Other modifications known in the art) and polysiloxanes. Suitable modified polysiloxanes include, but are not limited to, water dispersible polyalkylene oxide modified dimethylsiloxane graft copolymers having at least one alkylene oxide pendant chain having greater than 45 alkoxide units, as described in U.S. Pat. No. 5,356,859 (Lumu et al), incorporated herein by reference. Other suitable release agents include those available under the trade nameCrosslinked amino-modified polydimethylsiloxane supplied as an emulsion from stewartia. Some suitable articles of commerce of this type are described in the examples below.

Suitable amounts of one or more water-dispersible release agents in the dry image-receiving layer are generally at least 0.5% and up to and including 10% by weight, or typically at least 1% and up to and including 5% by weight, based on the total weight of the dry image-receiving layer. The amount of water-dispersible release agent refers to the amount of compound, not the amount of formulation or emulsion in which the compound can be supplied.

The aqueous coatable dye-receiving layer and receiver overcoat layer may also include residual crosslinking agents. Most of the crosslinkers used in the image-receiving layer formulations react during the preparation of the thermal image receiver elements, but some may remain in the aqueous coatable dye-receiving layer. Suitable crosslinking agents are described below.

Other Components-crosslinking Agents

Suitable crosslinkers that may be included in the aqueous image-receiving layer formulation and or the aqueous coatable receiver overcoat layer are selected to react with specific reactive groups on the water-dispersible acrylic polymer incorporated in the polymeric binder matrix. For example, in the case of reactive carboxyl and carboxylate groups, suitable crosslinkers are carbodiimides and aziridines.

One or more crosslinkers may be present in either or both of the aqueous image-receiving layer formulation or the aqueous receiver overcoat layer formulation in an amount substantially 1:1 molar ratio or less with the reactive groups in the water-dispersible acrylic polymer in the formulation. In general, suitable crosslinking agents include (but are not limited to): organic compounds such as melamine formaldehyde resins, glycoluril formaldehyde resins, polycarboxylic acids and anhydrides, polyamines, epichlorohydrin, diepoxides, dialdehydes, diols, carboxylic acid halides, ketenes, aziridines, carbodiimides, isocyanates and mixtures thereof.

The aqueous coatable ROC and the aqueous coatable DRL each can contain any one of the further following additional additions: plasticizers, defoamers, coating aids, charge control agents, thickeners or viscosity modifiers, antiblocking agents, UV absorbers, coalescing aids, matte beads (e.g., organic matte particles), antioxidants, stabilizers, and fillers as are known in the art for aqueous coating formulations. These optional additives may be provided in known amounts, including any amount ranging from 3% to 10% by weight of the total dry layer.

Additional and excess surfactant to DRL and ROC

The receiver overcoat layer comprises a polymeric binder matrix consisting essentially of: (1) a water-dispersible acrylic polymer and (2) a water-dispersible polyester, and (3) a water-dispersible conductive polymeric material. The ROC layer may further comprise one or more release agents, one or more crosslinking agents, one or more defoaming agents, and one or more surfactants or emulsifiers. In certain preferred embodiments, an amount of surfactant is added to the aqueous ROC dispersion. That is, the surfactant is added to the ROC dispersion after the acrylic polymer has been formed, in addition to the amount of surfactant used as an emulsifier in the manufacture or suspension of the acrylic polymer. Such added surfactants are therefore sometimes referred to herein as "additional surfactants". Those skilled in the art are aware of the fact that surfactants/emulsifiers are required to make acrylic polymers with water-dispersible properties.

In certain other embodiments, instead of adding "additional surfactant" after the water dispersible acrylic polymer is made, "excess surfactant" is added while the acrylic polymer is made. This excess surfactant is an additional amount of surfactant beyond that required to actually make the acrylic polymer and is added when the acrylic polymer is actually made. In general, 1% of surfactant is required to make the acrylic polymer. Thus, an "excess surfactant" is an amount of surfactant used to make the acrylic polymer that exceeds 1%. For example, fig. 5 provides a sample with "excess surfactant" (1% excess) added to the acrylic polymer composition and no "additional surfactant" added to the ROC layer. It is shown that the addition of surfactant in an amount of 2-4 wt% (1-3% excess surfactant) in formulating the acrylic polymer latex achieves acceptable results. Referring to fig. 5, different types of acrylic polymers were tested by adding excess surfactant during the formulation of such acrylic polymers. The tested acrylic polymers were formulated with specific monomers in varying weight ratios. The ratios are listed in fig. 5 as group (c)/group (a)/group (b), wherein the group (c) monomer is styrene or a styrene derivative, the group (a) monomer is an ethylenically unsaturated polymerizable acrylate or methacrylate containing an acyclic alkyl, cycloalkyl, or aryl ester group having at least 4 carbon atoms, and the group (b) monomer is a carboxyl-or sulfonic acid-containing ethylenically unsaturated polymerizable acrylate or methacrylate. All samples consisted of equal amounts of the same components, except for the acrylic polymer composition and the amount of excess surfactant added.

However, the inventors determined that acrylic polymers were made much better with the "normal" or conventionally required amount of surfactant, and then adding "additional surfactant" to the ROC. This provides better results (less misregistration and allows the use of less surfactant). Referring to fig. 4, when "extra" surfactant is added to the ROC and not in the manufacture of the water dispersible acrylic polymer as "excess surfactant" addition, only about 2.5 wt% surfactant is needed to achieve the desired alignment accuracy. FIG. 4 shows that for samples C1-C9, no additional surfactant was added to the ROC. For all those samples, misregistration occurred and the print quality was less than ideal. For samples E1-E7, the different types of additional surfactants were added in an amount of 2.5 mass% based on the total dry image receiving layer weight. For each of examples E1-E7, misregistration was reduced, or eliminated altogether, and print quality was acceptable.

Suitable surfactants are anionic or nonionic surfactants. Suitable anionic surfactants include, but are not limited to, the following:a-246 (sodium C14-C16 sulfonate),CO-436 (12-16% ethanol with 40% solids); dafakes (DOWFAX)2a1 (alkyl diphenyl oxide disulfonate), SDBS (sodium dodecyl benzene sulfonate) and ADS (sodium dodecyl sulfate). Suitable nonionic surfactants include, but are not limited to, the following: olin (Olin) -10G^TM(P-isononylphenoxypoly (glycidol)) or Sellwitt L-7230 (a copolymer of silicone, ethylene oxide and propylene oxide). The amount of "excess" or "additional" surfactant added to the formulation ranges from 1 wt% to 5 wt%, or from 2 wt% to 5 wt%, or from 3 wt% to 4 wt%. In certain embodiments, the additional surfactant is added to the formulation at about 2.5 wt%, or 1 wt% to 3 wt%, or 2 wt% to 2.5 wt%, or 2 wt% to 3 wt%.

By adding a surfactant to the ROC, the inventors were able to reduce the number of misalignments. Since misregistration appears to occur more often at the end of the donor strip spool, the present inventors determined visual alignment and alignment accuracy by testing and analyzing the last portion of the print image of the donor spool (e.g., the last 50 pages when the donor spool will typically print about 250 print images). As will be appreciated by those skilled in the art, when misregistration is present, the print quality is reduced because the lines, edges, or boundaries are blurred and unclear. In addition, misregistration results in improper coloration of the edges or borders due to the improper overlap of the various colors of the donor element transferred to the receiver element. For example, when the desired color is green, the blue and yellow dyes are transferred to the receiver element in superposition. When there is misregistration, the printed edge or border may appear yellow or blue rather than green, because there is no perfect overlap of blue and yellow dyes to achieve green.

Other Components-antifoam

For aqueous dispersion systems loaded with surfactants in the form of emulsifiers, surfactants, dispersants, etc., foaming tends to occur during the preparation of the dispersion and during any subsequent coating application process. Foaming occurs particularly when the dispersion (as previously discussed) is subjected to a high shear process. The high shear process comprises high speed stirring at about 1000rpm or more and high speed coating application at about 150mpm or more. During the high shear process, an undesirable amount of foam is generated, which often causes coating defects, undesirable compositional fluctuations and messy flooding, and other undesirable effects. In addition, excessive foaming requires frequent replacement of the filter of the applicator. To address these issues, it is advantageous to incorporate appropriate amounts of one or more defoamers into the aqueous dispersion for the ROC and DRL layers. The inventors have found that the addition of certain anti-foaming agents in certain amounts is effective in suppressing and controlling the foaming activity of aqueous DRL dispersions subjected to high shear processes. The defoamers described herein are generally water dispersible, with varying degrees of hydrophilicity/hydrophobicity balance. In addition, they typically (if not always) incorporate organic (e.g., amides, waxes, liquid hydrocarbons, etc.) and/or inorganic particles (e.g., fumed silica, colloidal silica, etc.) that also have varying degrees of hydrophilicity/hydrophilicity balance. Suitable defoamers include compounds having a high silicone content, such as structured siloxane defoamers, polyorganosiloxanes, resinous siloxane compounds, and polyether siloxane copolymers. Suitable anti-foaming agents include, but are not limited to, the commercially available anti-foaming agents listed in figure 7.

Figure 7 is a table showing how various concentrations of different types of antifoam affect the foam height above the initial liquid level after an aqueous dispersion has been subjected to a high shear process. The sample dispersions were each subjected to high speed mixing at 2000rpm for two minutes. Foam height measurements were taken immediately after the end of the mixing process ("0 minute after 2 minutes mixing"), one minute after the end of the mixing process, and two minutes after the end of the mixing process. As shown in fig. 7, control dispersion sample C1 included no defoamer, and as expected, the foam height above the initial liquid level was one of the highest levels observed for any sample. In addition, the foam remained at a level of about 5.1cm above the initial level after a two minute wait time after the end of the high shear stirring process. Each of the dispersion samples F1-F17 included varying amounts of defoamer, but none of those dispersion samples effectively reduced the foam content after the high shear stirring process. On the other hand, dispersion samples E10-E30 demonstrated more efficacy in reducing the foam content after the high shear stirring process. The results in fig. 7 demonstrate that certain types of defoamers are effective in reducing the foam content after the high shear process, while other types of defoamers are not effective in reducing the foam content. Each of the DRL dispersion samples listed in figure 7 contains all of the same components-i.e., water-dispersible acrylic polymer, water-dispersible polyester, release agent, cross-linking agent, and surfactant, except for the type of defoamer, the defoamer diluent used, and the amount of defoamer used.

Similarly, fig. 6 is a table showing how various concentrations of different types of antifoam affect the foam height above the initial level of several aqueous DRL dispersions. All dispersion samples E1-E12 and C13-C14 were aqueous DRL dispersions comprising the same crosslinker, release agent, water-dispersible polyester, and water-dispersible acrylic polymer. For each of the dispersant samples listed in fig. 6, the weight ratio of water-dispersible acrylic polymer to water-dispersible polyester present is approximately 9:1, and the water-dispersible acrylic polymer comprises about 3 wt% of the group (b) monomer-carboxyl-or sulfonic acid-group-containing ethylenically unsaturated polymerizable acrylate or methacrylate. Two control dispersion samples (C13 and C14) did not include an antifoaming agent. As expected, the foam heights of the two control samples were much higher than those of the exemplary samples (E1-E12) which all included some types of anti-foaming agents. Samples E7-E12 each showed extremely desirable results because the foam was completely reduced for only two minutes after mixing. As shown in fig. 6 and 7, it is advantageous to add the defoamer to the DRL in an amount equal to or greater than 0.04 wt%, or in a range of 0.04 to 0.32 wt%, or in an amount in a range of 0.16 to 0.32 wt%.

Several of the aqueous DRL dispersion embodiments of fig. 6 also included at least one surfactant and/or dispersant (except for control example C13, which did not include any surfactant or dispersant). Dispersants (Dispersing agents), also known as Dispersing agents, are generally materials that strongly absorb onto the pigment particles. To provide optimum performance, the pigment particles must function independently of each other and therefore must remain well dispersed throughout manufacture, storage, application, and film formation. To achieve these advantageous properties, certain embodiments of the present invention have a DRL comprising one or more surfactants and one or more dispersants. One or more surfactants may be present in an amount of up to approximately 10 wt%, or more specifically, 1 to 6 wt%, based on the total dry weight of the DRL. Similarly, one or more dispersants may be present in an amount up to approximately 10 wt%, or more specifically, 1 to 3 wt%, based on the total dry weight of the DRL.

As shown in FIG. 6, all dispersion samples except E10 and C13 included the surfactant Olin-10G^TM. In addition, FIG. 6 illustrates certain Olympic-10G-containing polymers^TMAnd aqueous DRL examples of one or more dispersants. Suitable dispersants are described below with reference to FIG. 8, and FS-30, which is commercially available from a variety of raw material suppliers, such as BASFOf FS-30 and DuPont (DUPONT)FS-30)。

ROC filterability

In certain embodiments, as previously described, dispersants or surfactants are used in the ROC and DRL to enhance dispersion stability. Inclusion of one or more surfactants and one or more dispersants in the ROC also improves filterability. It will be appreciated that variations of the thermal receiver element of the present invention may contain only one or more surfactants, only one or more dispersants, or a combination thereof in the ROC. Undesirable accumulation of dispersed particles and coagulation of ROC dispersions can be observed in the coater during or after the high speed, high shear coating process. The presence of build-up in the form of deposits and agglomerates requires frequent cleaning of the coating mechanism and filter replacement during the coating application process. Failure to monitor such accumulation and maintain a clean mechanism can thus affect coating quality. The present inventors have found that dispersion stability can be significantly enhanced by incorporating a suitable type and amount of dispersant, with improved filterability. The dispersant protects the latex and dispersed particles (or discontinuous phase particles) in the ROC dispersion from coagulation, flocculation, coagulation and coalescence under high shear and high stress conditions.

The dispersants used in the present invention are typically random or block copolymers or terpolymers. It may be ionic or non-ionic and has a weight average molecular weight in the range of from 5000 to 100,000. In the case where the dispersant is a random or block copolymer, the copolymer is generally composed of two types of monomer components: a hydrophilic monomer component and a hydrophobic and/or lipophilic monomer component-such as aliphatic, aromatic, alicyclic, aromatic heterocyclic, alicyclic heterocyclic, polycyclic compounds, and the like. In the case where the dispersant is a random or block terpolymer, it is also composed of two types of monomer components: at least one (but not more than two) hydrophilic monomeric component and at least one (but not more than two) hydrophobic and/or lipophilic monomeric component-such as aliphatic, aromatic, alicyclic, aromatic heterocyclic, alicyclic heterocyclic, polycyclic compounds and silicone-and/or fluorine-containing aliphatic, aromatic, alicyclic, aromatic heterocyclic, alicyclic heterocyclic, polycyclic compounds, and the like.

The above-mentioned characteristics of the dispersant can be exemplified as follows: for example, random copolymers of benzyl methacrylate and methacrylic acid (e.g., BE-23), random terpolymers of benzyl methacrylate, stearyl methacrylate and methacrylic acid (e.g., BOE), and acrylic block copolymers or terpolymers (e.g., available from BASF)PX 4701 andultra PX 4585). In addition, other suitable polymeric dispersants include E-SPERSE 100 and E-SPERSE 700 from Esox Chemicals (Ethox Chemicals), available from Air products (Air)) Is/are as followsSeries of aqueous dispersants from LuborunIs/are as followsAqueous hyperdispersant series, and Zephrym from Povida grass (CRODA)^TMA family of aqueous dispersants.

Filterability tests were performed and the results are detailed in fig. 8. Fig. 8 shows filterability of various ROC dispersions based on the filtrate quality test ("FQT") method, quantified by the weight of plugging ("WTP") measurement. To perform the FQT process, a sample of the solution was run through the test filter at constant pressure. The filtrate was collected and weighed until the aqueous solution flow stopped. The total weight of filtrate collected when the solution flow was stopped was recorded as WTP (results in grams in fig. 8). The higher the WTP, the better the filterability. The dispersion samples in fig. 8 were tested for filterability using a 32mm diameter, 1.2 micron membrane filter. Quantitative FQT results measured by WTP are detailed in the second to last columns of fig. 8. Based on internal testing, the inventors determined that certain quantitative results produced less acceptable results. The inventors therefore created a qualitative scale by which to grade and evaluate the various ROC dispersions tested. Qualitative assessments of ROC dispersions are provided in the last column of fig. 8. Quantitative-qualitative conversion was as follows:

FQT/WTP(gm)	filterability grading
		N<5	Unacceptable to slightly acceptable
5<N<20	Slightly acceptable to acceptable
		20<N<70	Can be accepted to very good
N>70	Very good to excellent

Still referring to fig. 8, the components of each sample of dispersion are detailed by the data listed in the columns numbered 1 through 10. Water was a component of all the ROC dispersions tested, as shown in column 1. In column 2, "L-3% E" means that a water-dispersible acrylic polymer is added to the dispersion. "L-3% E" means that the acrylic latex ("L") contains 3% of the type (b) carboxyl-or sulfonic acid group-containing ethylenically unsaturated polymerizable acrylate or methacrylate monomers previously discussed. In column 3, "XL-1" represents a crosslinking agent added to the dispersion. In column 4, "P" represents PEDOT, a water dispersible conductive polymeric material, added to the dispersion. In column 5, "S" represents a release agent added to the dispersion, i.e., a commercially available release agentIn column 6, "V" denotes addition to the dispersionMD-1480, a film-forming water-dispersible polyester. Columns 7 and 8 show the different solvents added to the dispersion samples. "IBA" represents the solvent isobutanol, and "DEG" represents diethylene glycol. Columns 9 and 10 illustrate the combination of surfactant and dispersant present in the ROC dispersion. Olin-10G previously discussed^TMAre generally used as surfactants, and BE-23, BOE,PX 4701, E-SPERSE 100, and E-SPERSE 700 (all discussed previously) are used as dispersants. FIG. 8 illustrates that the ROC dispersion may contain zero, one, or two dispersants. The dispersant may be included in the ROC in an amount ranging from 0.5% up to and including 10% by weight, or more specifically, 1% to 4% by weight, based on the total dry weight of the ROC layer. When drying aqueous coatable ROC and DRL formulations, it is understood that the solvent evaporates and does not account for any dry weight in either layer.

Microvoided flexible layer

Dye receiver elements for thermal dye transfer generally include a support (transparent or reflective) pressed on one or both sides thereof, a dye image-receiving layer, and optionally additional layers, such as a flexible or buffer layer between the support and the dye-receiving layer. Fig. 1A and 1B show an aqueous DRL layer on top of a microvoided flexible layer. In other embodiments (not shown), the dye-receiving layer may be coated directly on one or both opposing sides of the support. Alternatively, as seen in fig. 1A and 1B, the aqueous DRL can be coated on top of an additional layer (e.g., a flexible layer) that resides on one or both opposing sides of the support. The flexible layer provides thermal insulation to conserve heat generated by the thermal head at the printing surface, and also provides intimate contact between the donor strip and the receiver sheet, which is critical to uniform print quality. Various methods have been proposed to provide such flexible layers. Fig. 1A and 1B illustrate a similar microvoided flexible layer included between the outermost layer and the support. One skilled in the art will appreciate that the microvoided flexible layer may include one or more layers, such as a skin layer and a film layer. The microvoided flexible layer shown in fig. 1A and 1B is understood to be any type of flexible layer known in the art.

Support piece

The thermal image receiver element includes one or more layers as described above disposed on a suitable support. As mentioned above, these layers may be placed on one or both sides of the support. From the outermost surface to the support, the thermal image receiver element comprises an aqueous coatable dye-receiving layer and optionally one or more intermediate layers. However, in many embodiments, the aqueous coatable dye-receiving layer is disposed directly on one or both sides of the support. Particularly suitable supports comprise a polymeric film or a raw paper base comprising cellulosic fibres or a synthetic paper base comprising synthetic polymeric fibres or a resin coated cellulosic paper base. Other substrate supports such as fabrics and polymeric films may be used. The support may be constructed of any material typically used in thermal imaging applications so long as the layer formulations described herein may be suitably applied thereto.

The resin used on either or both sides of the paper substrate is a thermoplastic such as a polyolefin, e.g., polyethylene, polypropylene, copolymers of these resins, or blends of these resins, in a suitable dry thickness that can be adjusted to provide the desired curl characteristics. The surface roughness of such a resin layer can be adjusted to provide desired transport characteristics in a thermal imaging printer.

The support may be transparent or opaque, reflective or non-reflective. Opaque supports include plain paper, coated paper, resin-coated paper such as polyolefin-coated paper, synthetic paper, low density foam core based support and low density foam core based paper, photographic paper support, melt-extrusion-coated paper, and polyolefin-laminated paper.

The paper includes a wide range of papers, from high end papers such as photographic paper to low end papers such as newsprint. In one embodiment, use may be made of a material as described in U.S. Pat. Nos. 5,288,690 (Warner et al) and 5,250,496 (Warner et al)Paper (eastman kodak), all of which are incorporated herein by reference. The paper may be made on a standard continuous fourdrinier wire machine or other modern paper forming machine. Any pulp known in the art to provide paper may be used. Bleached hardwood chemical kraft pulp is suitable because it provides brightness, a smooth starting surface, and good formation while maintaining strength. Papers suitable for use in the present invention typically have a thickness of at least 50 μm and up to and including 230 μm and typically at least 100 μm and up to and including 190 μm, since the total imaging element thickness is then within the customer's desired range and so as to be processed in the original instrument. It may be "smooth" so as not to interfere with the viewing of the image. Chemical additives that impart hydrophobicity (sizing), wet strength, and dry strength can be used as desired. Such as TiO₂Talc, mica, BaSO₄And CaCO₃The inorganic filler material of the clay can be used to enhance optical properties and reduce cost as desired. Dyes, biocides, and processing chemicals may also be used as desired. The paper may also be subjected to smoothing operations such as dry or wet calendering and coating by an in-line or off-line paper coater.

A particularly suitable support is a paper base coated with resin on either side. The biaxial substrate support comprises a paper base and a biaxial polyolefin sheet, typically polypropylene, laminated to one or both sides of the paper base. Commercially available oriented and non-oriented polymer films such as opaque biaxially oriented polypropylene or polyester may also be used. Such supports may contain pigments, air voids, or foam voids to enhance their opacity. The support may also comprise a microporous material, such as PPG Industries, Inc. of Pittsburgh, Pennsylvania under the trade name PPG Industries, IncMaterials comprising polyethylene polymers are sold in the form of,synthetic paper (DuPont Corp.) impregnatedPaper, e.g.Andmembranes (Mobil Chemical Co.), and other composite membranes listed in U.S. Pat. No. 5,244,861, which is incorporated herein by reference. Suitable composite sheets are disclosed, for example, in U.S. patents 4,377,616 (Ashcraft et al), 4,758,462 (Park et al) and 4,632,869 (Park et al), the disclosures of which are incorporated by reference.

The support may be voided, meaning voids formed by added solid and liquid materials or "voids" containing gas. The void initiating particles held in the final packaging film core should be at least 0.1 μm and up to and including 10 μm in diameter and generally circular in shape to create voids of the desired shape and size. Microvoided polymeric films are particularly useful in some embodiments. For example, some commercial articles having these characteristics that can be used as supports are 350K18 and KTS-107 (HSI from south korea) available from ExxonMobil.

When described as having at least one layer, the biaxially oriented sheet may also be provided with additional layers that may be used to modify the properties of the biaxially oriented sheet. Such layers may contain coloring, antistatic or conductive materials or slip agents to produce flakes with unique characteristics. Biaxially oriented sheets may be formed from a surface layer, referred to herein as a skin layer, which will provide improved adhesion or orientation to the support and photographic element. Biaxially oriented extrusion can be carried out using up to 10 layers as necessary to achieve some particular desired properties. Biaxially oriented sheets may be made with layers of the same polymeric material, or they may be made with layers of different polymeric compositions.

Suitable transparent supports may be comprised of glass, cellulose derivatives such as cellulose esters, cellulose triacetate, cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate, polyesters such as poly (ethylene terephthalate), poly (ethylene naphthalate), poly-cyclohexanedimethylene-1, 4-terephthalate, poly (butylene terephthalate) and copolymers thereof, polyimides, polyamides, polycarbonates, polystyrenes, polyolefins such as polyethylene or polypropylene, polysulfones, polyacrylates, polyetherimides, and mixtures thereof. The term "transparent" as used herein means the ability to transmit visible radiation without significant deviation or absorption.

The thickness of the support used in the thermal image receiver element can be at least 50 μm and up to and including 500 μm or typically at least 75 μm and up to and including 350 μm. Antioxidants, brighteners, antistatic or conductive agents, plasticizers, and other known additives may be incorporated into the support, if desired.

Suitable antistatic agents in substrates such as raw stock include, but are not limited to, metal particles, metal oxides, inorganic oxides, metal antimonates, inorganic non-oxides, and electronically conductive polymers, examples of which are described in U.S. patent application 2011/0091667 (referenced above) incorporated herein by reference. Particularly suitable antistatic agents are inorganic or organic electrolytes. Such as sodium chloride, potassium chloride and calcium chloride, as well as alkali and alkaline earth metal salts (or electrolytes) of electrolytes containing polyacids are suitable. For example, alkali metal salts include salts of lithium, sodium or potassium polyacids, such as polyacrylic acid, poly (methacrylic acid), maleic acid, itaconic acid, crotonic acid, poly (sulfonic acid), or mixed polymers of these compounds. Alternatively, the proto-support may contain a variety of clays, such as montmorillonite clay, which include exchangeable ions that impart electrical conductivity to the proto-support. Polymeric alkylene oxides, such as those described in U.S. Pat. Nos. 4,542,095 (Steklenski et al) and 5,683,862 (Mazona et al) in combination with alkali metal salts are suitable for use as electrolytes.

The antistatic agent may be present in the support (e.g., a cellulose proto-based support) in an amount of up to 0.5 wt%, or typically at least 0.01 wt% and up to and including 0.4 wt%, based on total support dry weight.

In another embodiment, the substrate support comprises a synthetic paper that is generally cellulose free having a polymer core adhered to at least one flange layer. The polymeric core comprises a homopolymer, such as a polyolefin, polystyrene, polyester, polyvinyl chloride or other typical thermoplastic polymers, copolymers thereof or blends thereof, or other polymeric systems, such as polyurethanes and polyisocyanurates. These materials have been expanded by creating void space stretching or by using blowing agents to form two phases (a solid polymer matrix and a gas phase). Other solid materials may be present in the form of fillers of organic (polymeric, fibrous) or inorganic (glass, ceramic, metal) origin.

In yet another embodiment, the support comprises a synthetic paper that may be cellulose free having a foamed polymer core or a foamed polymer core adhered to at least one flange layer. The polymers described for the polymer core may also be used in the manufacture of the foamed polymer core layer by several mechanical, chemical or physical means as known in the art.

In many embodiments, polyolefins such as polyethylene and polypropylene, blends thereof, and copolymers thereof are used as the matrix polymer in the foamed polymer core along with chemical blowing agents such as sodium bicarbonate and mixtures thereof with citric acid, organic acid salts, azodicarbonamide, azodiisobutyronitrile, diazoaminobenzene, 4 '-oxybis (benzenesulfonylhydrazide) (OBSH), N' -dinitrosopentamethyl-tetramine (DNPA), sodium borohydride, and other blowing agents well known in the art. Suitable chemical blowing agents would be sodium bicarbonate/citric acid mixtures, azodicarbonamide; but other blowing agents may be used. These blowing agents may be used with auxiliary blowing agents, nucleating agents, and crosslinking agents.

When the thermal image receiver element comprises an aqueous coatable dye-receiving layer on only one side of the support, it may be useful to coat the "back" (non-imaged) of the support with a slip layer or anti-curl layer using a suitable polymer, such as polymers like acrylates or methacrylates, vinyl resins like copolymers derived from vinyl chloride and vinyl acetate, poly (vinyl alcohol-co-vinyl butyral), polyvinyl acetate, cellulose acetate, or ethyl cellulose. The back slip layer may also comprise one or more suitable antistatic or conductivity preventing agents known in the art. Such a sliding layer may also include a lubricant, such as an oil, or a semi-crystalline organic solid, such as beeswax, poly (vinyl stearyl), a perfluorinated alkyl ester polyether, polycaprolactone, silicone oil, or any combination thereof, as described in U.S. patent 5,866,506 (Tutt et al), which is incorporated herein by reference. Suitable anti-curl layers may comprise one or more polyolefins, such as a blend of polyethylene and polypropylene.

Method for manufacturing image receiver element

(A)Preparation of an image-receiving layer having an aqueous coatable dye-receiving layer as the outermost layer (without aqueous Dispersion) Single layer DRL of sexually conductive polymeric material

The image-receiving layer is prepared by applying an image-receiving layer formulation that receives an aqueous coatable dye to at least one side of the support, and in some embodiments, the same or different aqueous coatable dye-receiving layer formulation may be applied to opposite sides of the support to result in a duplex thermal image-receiving element.

The coated aqueous coatable dye-receiving layer formulation comprises a polymeric binder composition consisting essentially of: the (1) and (2) polymer components and any optional addenda described above, such as surfactants used as emulsifiers for making the water-dispersible acrylic polymer, one or more release agents, one or more crosslinking agents, and any other addenda described herein. The weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 6:1, or typically at least 1.5:1 to and including 5: 1. Preferably, the weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 9.2: 1. In certain embodiments, the one or more water-dispersible acrylic polymers are present in the polymeric binder matrix at a dry ratio to water-dispersible polyester of at least 1:1, or typically at least 4:1 and up to and including 20:1, or more likely at least 1:1 and up to and including 20:1, or even at least 4:1 and up to and including 15: 1. These formulations may be applied to the support using any suitable technique, including coating under appropriate equipment and conditions, including (but not limited to) hopper coating, curtain coating, rod coating, gravure coating, roll coating, dip coating, and spray coating. The support material is as described above, but prior to application of the aqueous coatable dye-receiving layer formulation, the support may be treated using any suitable technique to improve adhesion, such as acid etching, flame treatment, corona discharge treatment, or glow discharge treatment, or it may be treated with a suitable base coat.

(B)Preparation of image-receiving layer having conductive Polymer in aqueous coatable dye-receiving layer as outermost layer (Single layer DRL with Water dispersible conductive polymeric Material)

The conductive image-receiving layer is prepared by applying an aqueous coatable dye-receiving layer formulation comprising a conductive polymer to at least one side of the support, and in some embodiments, the same or different aqueous coatable dye-receiving layer formulation may be applied to the opposite side of the support to give a duplex thermal image-receiving element.

The coated aqueous coatable dye-receiving layer formulation comprises a polymeric binder composition consisting essentially of: the water-dispersible acrylic polymer of the present invention may be prepared by (1) a water-dispersible acrylic polymer, (2) a water-dispersible polyester, and (3) a water-dispersible conductive polymeric material component, as described above, and any optional addenda, such as one or more surfactants or dispersants that act as emulsifiers for the water-dispersible acrylic polymer, one or more release agents, one or more crosslinking agents, and any other addenda described above. The weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 6:1, or typically at least 1.5:1 to and including 5: 1. Preferably, the weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 9.2: 1. In certain embodiments, the one or more water-dispersible acrylic polymers are present in the polymeric binder matrix at a dry ratio to water-dispersible polyester of at least 1:1, or typically at least 4:1 and up to and including 20:1, or more likely at least 1:1 and up to and including 20:1, or even at least 4:1 and up to and including 15: 1. The amount of (3) the water-dispersible conductive polymeric material in the formulation ranges from > 0.75% to 2% or 1.0% to 1.25%. These formulations can be coated onto a support using any suitable technique, including coating under appropriate equipment and conditions, including (but not limited to) hopper coating, curtain coating, rod coating, gravure coating, roll coating, dip coating, and spray coating. The support material is as described above, but prior to application of the aqueous coatable dye-receiving layer formulation, the support may be treated using any suitable technique to improve adhesion, such as acid etching, flame treatment, corona discharge treatment, or glow discharge treatment, or it may be treated with a suitable base coat.

(C)Preparation of image receiving layer with conductive Polymer in aqueous coatable overcoat (Water in ROC layer) Double layer of dispersed conductive polymeric materials DRL (ROC/DRL)

The image-receiving layer is composed of two layers, an aqueous coatable dye-receiving layer and an aqueous coatable overcoat layer comprising a conductive polymer.

The image layer is prepared by first applying an image-receiving layer formulation that receives an aqueous coatable dye to at least one side of the support, and in some embodiments, the same or different aqueous coatable dye-receiving layer formulation may be applied to the opposite side of the support to result in a duplex thermal image-receiving element.

The coated aqueous coatable dye-receiving layer formulation comprises a polymeric binder composition consisting essentially of: the above-described (1) water-dispersible acrylic polymer and (2) water-dispersible polyester component, and any optional additives, such as one or more surfactants or dispersants that act as emulsifiers for making the water-dispersible acrylic polymer, one or more release agents, one or more crosslinking agents, and any other additives described herein. The weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 6:1, or typically at least 1.5:1 to and including 5: 1. Preferably, the weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 9.2: 1. In certain embodiments, the one or more water-dispersible acrylic polymers are present in the polymeric binder matrix at a dry ratio to water-dispersible polyester of at least 1:1, or typically at least 4:1 and up to and including 20:1, or more likely at least 1:1 and up to and including 20:1, or even at least 4:1 and up to and including 15: 1.

These formulations can be coated onto a support using any suitable technique including coating under the appropriate equipment and conditions, including but not limited to hopper coating, curtain coating, rod coating, gravure coating, roll coating, dip coating, and spray coating. The support material is described herein, but prior to application of the aqueous coatable dye-receiving layer formulation, the support may be treated using any suitable technique such as acid etching, flame treatment, corona discharge treatment, or glow discharge treatment to improve adhesion or it may be treated with a suitable base coat.

Next, an overcoat layer is prepared by applying an image-receiving layer formulation comprising an overcoated conductive polymer that receives an aqueous coatable dye to the dye-receiving layer at least on one side of the support coated with the aqueous coatable dye-receiving layer, and in some embodiments, the same or a different aqueous coatable dye-receiving layer formulation comprising a conductive polymer can be applied to the opposite side of the support coated with the aqueous coatable dye-receiving layer to yield a duplex thermal image-receiving element.

The coated aqueous coatable overcoat formulation comprises a polymeric binder composition consisting essentially of: the above-described (1) water-dispersible acrylic polymer, (2) water-dispersible polyester, and (3) water-dispersible conductive polymeric material component, and any optional addenda, such as one or more surfactant or dispersant (described herein), one or more release agent, one or more crosslinking agent (described herein), and any other addenda described herein, used as emulsifiers for making the water-dispersible acrylic polymer. The weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 6:1, or typically at least 1.5:1 to and including 5: 1. Preferably, the weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 9.2: 1. In certain embodiments, the one or more water-dispersible acrylic polymers are present in the polymeric binder matrix at a dry ratio to water-dispersible polyester of at least 1:1, or typically at least 4:1 and up to and including 20:1, or more likely at least 1:1 and up to and including 20:1, or even at least 4:1 and up to and including 15: 1. The amount of water-dispersible conductive polymeric material in the formulation ranges from >1.2 wt% to 3 wt%, >1 wt% to 3 wt%, or >1 wt%, >1.4 wt%. These formulations can be coated onto a support using any suitable technique including coating under the appropriate equipment and conditions, including but not limited to hopper coating, curtain coating, rod coating, gravure coating, roll coating, dip coating, and spray coating. The support material is described above, but prior to application of the aqueous coatable dye-receiving layer formulation, the support may be treated using any suitable technique such as acid etching, flame treatment, corona discharge treatment, or glow discharge treatment to improve adhesion or it may be treated with a suitable base coat.

(D)Preparation of image-receiving layer with additional surfactant and conductive polymer in overcoat (in ROC layer) Dual layer DRL (ROC/DRL) with additional surfactant and water dispersible conductive polymeric material

The image-receiving layer comprises two layers, an aqueous coatable dye-receiving layer and an aqueous coatable overcoat layer comprising additional surfactant and a conductive polymer.

The image layer is prepared by first applying an image-receiving layer formulation that receives an aqueous coatable dye to at least one side of the support, and in some embodiments, the same or different aqueous coatable dye-receiving layer formulation may be applied to the opposite side of the support to result in a duplex thermal image-receiving element.

The coated aqueous coatable dye-receiving layer formulation comprises a polymeric binder composition consisting essentially of: the above-described (1) water-dispersible acrylic polymer and (2) water-dispersible polyester component, and any optional addenda, such as a surfactant that acts as an emulsifier for making the water-dispersible acrylic polymer, one or more release agents, one or more crosslinking agents, and any other addenda described herein. The weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 6:1, or typically at least 1.5:1 to and including 5: 1. Preferably, the weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 9.2: 1.

In certain embodiments, the one or more water-dispersible acrylic polymers are present in the polymeric binder matrix at a dry ratio to water-dispersible polyester of at least 1:1, or typically at least 4:1 and up to and including 20:1, and more likely at least 1:1 and up to and including 20:1, or even at least 4:1 and up to and including 15: 1.

These formulations can be coated onto a support using any suitable technique including coating under the appropriate equipment and conditions, including but not limited to hopper coating, curtain coating, rod coating, gravure coating, roll coating, dip coating, and spray coating. The support material is described above, but prior to application of the aqueous coatable dye-receiving layer formulation, the support may be treated using any suitable technique such as acid etching, flame treatment, corona discharge treatment, or glow discharge treatment to improve adhesion or it may be treated with a suitable base coat.

Next, an overcoat layer is prepared by applying an image-receiving layer formulation comprising an additional surfactant and a conductive polymer that receives an aqueous coatable dye to the aqueous coatable dye-receiving layer described herein (or as described in (a)) at least on one side of the support coated with the aqueous coatable dye-receiving layer, and in some embodiments, the same or different aqueous coatable dye-receiving layer formulation comprising an additional surfactant and a conductive polymer can be applied to the opposite side of the support coated with the aqueous coatable dye-receiving layer to give a duplex thermal image-receiving element.

The coated aqueous coatable overcoat formulation comprises a polymeric binder composition consisting essentially of: as described herein, (1) a water-dispersible acrylic polymer, (2) a water-dispersible polyester, and (3) a water-dispersible conductive polymeric material component and additional surfactant, and optional adjuncts, such as a surfactant used in the emulsification of a water-dispersible acrylic polymer, one or more release agents, one or more crosslinking agents, and any other adjunct described herein. The weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 6:1, or typically at least 1.5:1 to and including 5: 1. Preferably, the weight ratio of water-dispersible acrylic polymer to water-dispersible polyester in such formulations is at least 1:1 to and including 9.2: 1. In certain embodiments, the one or more water-dispersible acrylic polymers are present in the polymeric binder matrix at a dry ratio to water-dispersible polyester of at least 1:1, or typically at least 4:1 and up to and including 20:1, or more likely at least 1:1 and up to and including 20:1, or even at least 4:1 and up to and including 15: 1.

The amount of water dispersible conductive polymeric material is as discussed above. The amount of additional surfactant added to the formulation is as discussed above.

These formulations can be coated onto a support using any suitable technique including coating with appropriate equipment and conditions, including but not limited to hopper coating, curtain coating, rod coating, gravure coating, roll coating, dip coating, and spray coating. The support material is described above, but prior to application of the aqueous coatable dye-receiving layer formulation, the support may be treated using any suitable technique such as acid etching, flame treatment, corona discharge treatment, or glow discharge treatment to improve adhesion or it may be treated with a suitable base coat.

After the formulation is coated as described in (a) to (D) above, it is dried under suitable conditions at a temperature of at least 20 ℃ and up to and including 100 ℃, and typically at least 60 ℃. If desired, drying may be carried out in an oven or drying chamber, in particular in a manufacturing plant or production line. Drying facilitates crosslinking of the aqueous image-receiving layer formulation, particularly through reactive groups in the water-dispersible acrylic polymer using a suitable crosslinking agent. Crosslinking can improve adhesion of the aqueous coatable dye-receiving layer to the support or any proximate layer disposed beneath the aqueous coatable dye-receiving layer.

If desired, after the aqueous coatable dye-receiving layer formulation is dried, it may be additionally heat treated to enhance crosslinking of at least some of the water-dispersible acrylic polymer, and this heat treatment may be carried out in any suitable manner, with suitable equipment such as an oven, for a period of time required to continuously remove at least 95% of the water in the aqueous coatable dye-receiving layer formulation at a temperature of at least 70 ℃.

While the aqueous coatable dye-receiving layer formulation is generally applied to the support in a uniform manner to cover most or the entire support surface, it is sometimes applied to the support and dried in a manner to form a predetermined pattern of the aqueous coatable dye-receiving layer.

While the aqueous coatable dye-receiving layer formulation may be applied directly onto either or both sides of the support, in some embodiments, one or more intermediate layer formulations may be applied directly onto one or both sides of the support to result in one or more intermediate layers as described above. Once the one or more intermediate layer formulations are applied and dried to form the one or more intermediate layers, the aqueous coatable dye-receiving layer formulation is then applied to the one or more intermediate layers on one or both sides of the support. For example, the intermediate layer may be coated with a suitable formulation to provide buffering, thermal insulation, antistatic properties, or other desired properties to enhance manufacturability, element stability, thermal image transfer, and image stability.

The interlayer formulation is also typically applied in the form of an aqueous composition in which the various polymeric components and any fillers, surfactants, antistatic agents, and other desired components are dispersed or dissolved in water or water/alcohol solvents. As mentioned above, the interlayer formulation may be applied using any suitable technique.

Thermal donor element

Thermal donor elements can be used with the thermal image receiver elements of the present invention to provide thermal transfer of dyes, transparent polymeric films, or metallic effects. Such thermal donor elements generally comprise a support having thereon a layer containing an ink or dye (sometimes referred to as a thermal dye donor layer), a layer of thermally transferable polymeric film or metal particles or sheets.

Any ink or dye may be used in the thermal donor element, provided that it can be transferred to the dry image receiving layer of the thermal image receiver element by heating. Thermal donor elements are described, for example, in U.S. patents 4,916,112 (Henzel et al), 4,927,803 (Bailey et al), and 5,023,228 (Henzel), which are incorporated herein by reference. In a printed thermal dye transfer method, a thermal donor element comprising a poly (ethylene terephthalate) support coated with sequential repeating regions (e.g., patches) of blue, magenta, or yellow inks or dyes may be used, and the ink or dye transfer steps may be performed sequentially for each color to obtain a multi-color ink or dye transfer image on either or both sides of the thermal image receiver element. The support may comprise black ink to facilitate marking of logos or text.

The thermal donor element can also include a clear protective layer ("delamination") that can be thermally transferred to the thermal image receiver element throughout the transfer dye image or in an unstained portion of the thermal image receiver element. When the process is performed using only a single color, a single color ink or dye transfer image can be subsequently obtained.

The thermal donor element conventionally comprises a support having thereon a layer containing a dye. Any dye may be used in the dye-containing layer provided that it can be transferred to the dried image-receiving layer by a heating operation.

Thermal donor elements can include single color regions (patches) or multiple colored regions (patches) containing dyes suitable for thermal printing. As used herein, a "dye" may be one or more dyes, pigments, colorants, or combinations thereof, and may optionally be in a binder or carrier as known to practitioners in the art. For example, the dye layer may include a magenta dye combination and further include a yellow dye donor segment including at least one bis-pyrazolone-methine dye and at least one other pyrazolone-methine dye and a blue dye donor segment including at least one indoaniline blue dye. The dyes may be selected in consideration of the hue, light fastness and solubility of the dyes in the dye-containing layer binder and the aqueous coatable dye-receiving layer binder.

Other examples of suitable dyes can be found in U.S. patent 4,541,830 (horiba et al); 4,698,651 (Moore et al); 4,695,287 (Evans et al); 4,701,439 (Evan et al); 4,757,046 (Bayer et al); 4,743,582 (Evan et al); 4,769,360 (Evan et al); 4,753,922 (Bayer et al); 4,910,187 (Zongteng (Sato et al)); 5,026,677 (Vanmalele); 5,101,035 (Bach et al); 5,142,089 (Vanmell); 5,374,601 (Longotan (Takiguchi) et al); 5,476,943( village (Komamura) et al); 5,532,202 (Yoshida); 5,635,440 (estuary (Eguchi) et al); 5,804,531 (Evan et al); 6,265,345 (Jitian et al); and 7,501,382 (Foster et al) and U.S. patent application publications 2003/0181331 (Foster et al) and 2008/0254383 (vice island (Soejima et al), the disclosures of which are hereby incorporated by reference.

Dyes may be employed alone or in combination to obtain a monochromatic dye donor layer or a black dye donor layer. An amount of dye can be used in the donor transfer element to provide 0.05g/m in the final dye image upon transfer²To and including 1g/m²。

The dye and optional addenda are generally incorporated into a suitable binder in the dye-containing layer. Such binders are well known in the art and may include cellulosic polymers, different types of polyvinyl acetate, polyvinyl butyral, styrene containing polyol resins, combinations thereof and the like, as described, for example, in U.S. patent 6,692,879 (Suzuki et al), 8,105,978 (Yoshizawa et al), and 8,114,813 (gize et al), 8,129,309 (Yokozawa et al), and U.S. patent application publications 2005/0227023 (quarki et al) and 2009/0252903 (presque (Teramae et al), all of which are incorporated herein by reference.

The dye-containing layer may also include a variety of additives such as surfactants, antioxidants, UV absorbers, or non-transferable colorants in amounts known in the art. For example, suitable antioxidants or light stabilizers are described, for example, in U.S. patent 4,855,281 (bayer) and U.S. patent application publications 2010/0218887 and 2011/0067804 (both frieland), which are incorporated herein by reference. The hindered amine derived nitroxide radicals described in the frieland publication are particularly useful as light stabilizers for use in transferring dye layers and thermal transfer dye images in protective overcoats applied over the transfer dye image.

A polymeric film ("laminate") can be thermally transferred from a donor transfer element onto a thermal image receiver element. Compositions of such polymeric films are known in the art as described, for example, in U.S. patent 6,031,556 (tatter et al) and 6,369,844 (newmann et al), which are incorporated herein by reference. The two frieland publications described above provide a description of protective polymeric films, their compositions and uses.

In some embodiments, the thermal donor element comprises a layer of a metal or metal salt that can be thermally transferred to the thermal image receiver element. Such metals can provide a metallic effect, highlight or base coat for subsequent transfer of the dye image. Suitable metals that can be transferred include, but are not limited to, gold, copper, silver, aluminum, and other metals as described below. Such thermal donor elements are described, for example, in U.S. Pat. Nos. 5,312,683 (Zhou et al) and 6,703,088 (forest (Hayashi et al), both incorporated herein by reference.

As described in, for example, the frieland publication mentioned above, the back side of the thermal donor element can include a "slip" or "glide" layer.

Imaging assembly and thermal imaging

Thermal image receiver elements may be used in combination or "thermal bonding" with one or more thermal donor elements in the assemblies of the present invention to provide thermal transfer or images (e.g., dyes, metals, or clear films) on one or more sides using thermal transfer means. Multiple thermal transfer means to the same side, opposite side, or both sides of the thermal image receiver element can provide a multi-color image, polymeric film, or metallic image on one or both sides of the substrate of the thermal image receiver element. As mentioned above, the metal layer or pattern may be formed on one or both sides of the substrate. In addition, a protective polymeric film (topcoat) may also be applied to one or both sides of the substrate, for example to cover a multi-color image on one or both sides of the substrate with a protective topcoat or "laminate".

Thermal transfer generally comprises imagewise heating a thermal donor element and a thermal image receiver element of the invention and transferring a dye, metal or clear film image onto the thermal image receiver element as described above to form a dye, metal or polymeric film image. Thus, in some embodiments, both the dye image and the polymeric film are image-wise transferred from one or more thermal donor elements onto the aqueous coatable dye-receiving layer of the thermal image receiver element.

A thermal dye donor element comprising a poly (ethylene terephthalate) support coated with sequentially repeating regions of blue, magenta, and yellow dyes (optionally black dyes or pigments) may be employed, and the dye transfer steps performed sequentially for each color to obtain a three-color (or four-color) dye transfer image on either or both sides of the support of the thermal image receiver element. Thermal transfer of the polymeric film may also be accomplished in the same or different processes to provide a protective overcoat on either or both sides of the support. As mentioned above, the thermal donor element can also be used to transfer metal onto either or both sides of the thermal image transfer element.

Thermal printheads that can be used to transfer inks, dyes, metals, or polymeric films from a thermal donor element to a thermal image receiver element are commercially available. For example, a Fujitsu (Fujitsu) thermal head (FTP-040MCS001), a TDK thermal head F415HH7-1089, or a Rohm (Rohm) thermal head KE 2008-F3 may be employed. Alternatively, other known energy sources for transfer may be used, such as a laser, as described, for example, in GB publication 2,083,726A, which is incorporated herein by reference.

An imaging assembly generally comprises (a) a thermal donor element and (b) a thermal image receiver element of the present invention in superposed relationship with the thermal donor element such that the dye-containing layer, polymeric film, or metal of the thermal donor element is thermally bonded or in intimate contact with the aqueous coatable dye-receiving layer. Imaging can be performed using known procedures using such assemblies.

When three color images are obtained, the imaging assembly can be formed on three different occasions during the application of heat by a thermal print head or laser. After the first dye is transferred from the first thermal donor element, the element can be peeled. A second thermal donor element (or another region of the same thermal donor element with a different dye region) can then be aligned with the aqueous coatable dye-receiving layer and the process repeated. Three or more color images may be obtained in the same manner. A metal layer (or pattern) or a clear laminate protective film can be obtained in the same manner.

The imaging method may be performed using a single head printing apparatus or a dual head printing apparatus, where either head may be used for one or both sides of the imaging support. In a printing operation, a capstan roller can be used to transport the bidirectional thermal image receiver element of the present invention before, during, or after the formation of an image. In some cases, the bidirectional thermal image receiver element is placed within a carousel that is used to position either side of the bidirectional thermal image receiver element in relation to the print head used for imaging. In this way, a clear film, metal pattern or layer can be transferred to either or both sides along with multiple transfer color images.

The bidirectional thermal image receiver elements of the present invention may also receive consistent or pattern-by-pattern transfer of metals, including but not limited to aluminum, copper, silver, gold, titanium, nickel, iron, chromium, or zinc, to either or both sides of the substrate. Such a metallized "layer" may be located throughout a single or multi-color image or the metallized layer may be the only "image". Metal-containing particles can also be transferred. The metal or metal-containing particles can be transferred in the presence or absence of a polymeric binder. For example, the transferable heat can soften the metal sheet in the adhesive as described, for example, in U.S. patent 5,312,683 (referenced above). Transfer of aluminum powder is described in us patent 6,703,088 (mentioned above). If desired, multiple metals can be thermally transferred to achieve unique metallic effects. For example, one metal may be transferred to form a uniform metal layer and a second metal transferred to provide a desired pattern on the uniform metal layer. The transferred metal or metal-containing particles can be provided in a strip or ribbon of such material in the thermal donor element.

The following examples are provided to illustrate the practice of the invention and are not intended to be limiting in any way.

Copolymers for producing water-dispersible acrylic polymers

Various copolymers were prepared to facilitate evaluation of thermal image receiver elements, and these copolymers were prepared using the following procedures and components. An emulsion of ethylenically unsaturated polymerizable monomers was prepared using the following composition:

monomer emulsion：

Monomer (Table I) 400g

395g of water

A-246L surfactant

(Suwill Rhodia) (Solvay Rhodia) 5g

Reactor contents:

195g of water

5g of A-246L surfactant

45％KOH 1.54g

“ACVA” 2g

The polymerization procedure was carried out as follows:

1) mixing water withA-246L of surfactant was added to the reactor and the mixture was heated to 75 ℃.

2) Emulsions were prepared using ethylenically unsaturated polymerizable monomers having the initial mol% of each monomer as set forth in table I below.

3) Azobiscyanovaleric acid (ACVA) free radical initiator and 45 wt% potassium hydroxide were added to the reactor.

4) The monomer emulsion was metered into the reactor for 6 hours.

5) The reaction mixture was maintained at 75 ℃ for an additional 3 hours, and then the reaction mixture was cooled to 25 ℃.

6) The reaction mixture was adjusted using 1N KOH to obtain the desired pH.

Table I: monomer ratio for producing water-dispersible acrylic polymer in mol%

Table II below describes the chemical properties of a water-dispersible acrylic polymer (in emulsion form) prepared using the ethylenically unsaturated polymerizable monomers shown in table I.

TABLE II

Examples of the invention

Forming thermal image receiver elements

The use is designed to provide a composition having a viscosity of 2.2g/m²Aqueous image-receiving layer formulations of dry coverage dye image-receiving layers all control examples and inventive examples I1 to I58 were prepared. For invention examples I59-I73, the aqueous image-receiving layer formulation was designed to provide a toner having a density of 1.1g/m²Dry coverage of the image receiving layer. Furthermore, all aqueous image receiving layer formulations were designed to have approximately 10% solids, which would include all of the solid components shown for each formulation in table III below.

For the control C1 formulation, all solids were water dispersible polyesters that provided 100% solids in the resulting dye image-receiving layer: (MD-1480, provided as a 25% by weight dispersion in water, from). Control C1 image-receiving layer formulation was prepared by dispersing water dispersible polyester in water only with brief agitation, and similarly a control C2 image-receiving layer formulation was prepared having the same 98% solids of water dispersible polyester dispersion and a mold release agent: (E2150) 2% solids.

To prepare control formulations C3 to C31 and inventive formulations I1 to I29, the release agent (35 wt% dispersion) was diluted with about 258g of water and the acrylic polymer emulsion (see table II for% solids) was then added to this mixture with brief stirring. Control formulations C3-C31 were free of water dispersible polyester.

For each of the inventive formulations I1-I29, the resulting image-receiving layer comprises 30 weight percent of a water-dispersible polyester: (MD-1480, provided as a 25% by weight dispersion in water, from) 67% by weight of an acrylic polymer and 3% by weight of a mold release agent (B)E2150, provided as a 35% by weight dispersion in water from stati).

For each of the inventive formulations I30-I58, the resulting image-receiving layer comprises 30 weight percent of a water-dispersible polyester: (MD-1480, provided as a 25% by weight dispersion in water, from) 64% by weight of an acrylic polymer, 4% by weight of a crosslinking agent (carbodiimide XL-1, provided in the form of a 40% by weight dispersion in water from DSM) and 2% by weight of a mold release agent (release agent)E2150) In that respect To prepare the inventive formulations I30 to I58, the mold release agent (35% by weight dispersion) was diluted with about 243g of water and then about 42g of the polyester dispersion (25% by weight dispersion) was added to this mixture, followed by the addition of the acrylic polymer (see table II for% solids) and carbodiimide crosslinker XL-1 (40% by weight dispersion) with brief stirring.

For each of the inventive formulations I59-I73, the resulting image-receiving layer comprises 15 wt.% of a water-dispersible polyester (I)MD-1480, provided as a 25% by weight dispersion in water, from) 32% by weight of an acrylic polymer, 1% by weight of a crosslinking agent (carbodiimide XL-1, provided in the form of a 40% by weight dispersion in water from DSM) and 1% by weight of a mold release agent (release agent)E2150)。

Each dye image-receiving layer formulation was machine coated onto a substrate sample comprising a microvoided layer on the opposite side of a paper stock base (such as a KTS-107 laminate available from south Korean HSI) and dried to provide a resulting dried image-receiving layer with 2.2 (or 1.1) g/m²Dry coverage of. There is no intermediate layer between the support of any of the thermal image receiving elements and the dry image receiving layer.

For each of the inventive formulations I74 and I75, the resulting image-receiving layer comprised 9 and 6.8 weight percent, respectively, of a water-dispersible polyester: (A)MD-1480, provided as a 25% by weight dispersion in water, from) 80.8 and 81.2% by weight of acrylic polymer, 9 and 11% by weight of crosslinker (carbodiimide XL-1, provided in the form of a 40% by weight dispersion in water from DSM) and 1.2 and 1% by weight of mold release agent: (acrylic acid copolymer)E2150)。

Each dye image-receiving layer formulation was machine coated onto a substrate sample comprising a microvoided layer on the opposite side of a paper stock base (such as an Exxon Mobil sweet (Vulcan) laminate available from Exxon Mobil, USA) and dried to provide 1.32g/m for the resulting dried image-receiving layer²Dry coverage of. There is no intermediate layer between the support of any of the thermal image receiving elements and the dry image receiving layer.

Various properties of each of the control and inventive dye image-receiving layer formulations and the resulting thermal image receiver elements were evaluated in the following manner.

Quality of the coating

The coating quality was assessed visually (not magnified) and given one of three ratings. A "poor" visual rating means that the coated and dried image-receiving layer is not uniform because the coating lines are visible and the network (mottling) is extremely prominent. By "acceptable" visual grade is meant that some coating lines and webs are apparent but the dry image receiving layer quality is acceptable. By "good" visual assessment is meant that the dried image-receiving layer is extremely uniformly glossy and smooth, with no visibly noticeable streaks or networks of coating.

Donor-receiver adhesion

After "printing" or forming the thermal assembly of the donor element and thermal image receiver element, the donor-receiver adhesion quality was visually assessed (not magnified). The assessment of "poor" means that the dye donor layer in the donor element generally delaminates from the donor element support during thermal dye transfer (printing). The evaluation of "ok" means that the dye donor layer did not delaminate from the donor element support, but there was flutter noise in the printer and some flutter streaks in some of the resulting thermal transfer dye images. A "good" evaluation means that there are no apparent adhesion defects in the resulting thermal transfer dye image.

Gray scale transitions

A smooth gradual transition in optical density is critical for high quality high optical printing. Therefore, the measurement of the gray level transition in low optical density areas (as in the case of highlight printing) is evaluated visually (without magnification) by: measuring 18 incremental optical density levels from minimum density (D)_{Minimum size}Or energy level 18) to maximum density (D)_{Maximum of}>1.5 or energy level 1), and certain image loss or optical density discontinuities are observed at the maximum density level (level x), which can also be effectively accounted for in the sensitization curve (i.e., optical density versus energy level) and the associated sensitization data.

Evaluation of "not good" the evaluation of "not good" means that the obtained grade x and the grade 18 (or D)_{Minimum size}) Difference in optical density therebetween, i.e. Δ OD<0.015, or based on the sensitization curve, stage x and stage 18 (or D)_{Minimum size}) Least square slope between<0.002 (absolute). An evaluation of "ok" means that the obtained level x and level 18 (or D)_{Minimum size}) The difference in optical density (Δ OD) between is at least 0.010 to 0.058, or based on the sensitization curve, stage x and stage 18 (or D)_{Minimum size}) The least squares slope in between is at least 0.002 to 0.006 (absolute). A "good" assessment means that the obtained stage x and stage 18 (or D)_{Minimum size}) Difference in optical density therebetween, i.e. Δ OD>0.042, or based on the sensitization curve, stage x and stage 18 (or D)_{Minimum size}) Least square slope between>0.006 (absolute).

Neutral (neutral red, green or blue) D_{Maximum of}

Neutral color D as used in the practice of the present invention_{Maximum of}A target maximum optical density measure of neutral hue which is such thatObtained from imagewise thermal printing with a given set of dye donor elements, thermal image receiver elements, and thermal printing conditions. Because of the target neutral hue, D of neutral color_{Maximum of}Composed of a composite color of thermally transferred yellow, magenta, and cyan dyes from corresponding color dye donor element patches, the optical densities of the corresponding color dyes, i.e., D, can be obtained in the printed thermal image using a Grave Makeh white (Gretag Macbeth) spectral scanner_{Maximum of}(neutral Red) D_{Maximum of}(neutral color green) and D_{Maximum of}(neutral blue). Of the results shown in Table III below, the smaller absolute value is preferred because it displays image colors from D_{Maximum of}The shift in the target optical density is smaller and the color image is therefore closer to the target optical density.

The results of these evaluations are provided in table III below. It is apparent from these results that while the control formulation and thermal image receiver element provide some good quality, they do not always provide all of the desired characteristics. However, the inventive formulations and thermal image receiver elements provide the desired results with most, if not all, of the desired characteristics.

In particular, it is apparent that in the absence of film-forming polyester, the coating quality (as a result of the characteristics) and as listed below in table III such as donor-receiver adhesion, print uniformity, and dye transfer efficiency (such as D)_{Maximum of}) The overall printing (image) performance of (b) is generally degraded and less satisfactory as a higher quality color image. For example, when comparing controls C3-C5, invention I1-I3, and invention I30-32, the coating quality and donor-receiver adhesion performance of the controls were less good than the examples of the invention. When comparing control groups C8-23 and C-28, inventive examples I6-I18 and inventive examples I25-I50, all examples showed good donor-receiver adhesion properties, but D of the control group examples_{Maximum of}Value significantly higher than D of the inventive examples_{Maximum of}The worse the value.

When acrylic latex is not present (controls C1 and C2), the donor strip (element) does not separate easily during the thermal printing process, and it typically sticks tightly to the thermal image receiving element, causing serious print and print quality problems. Furthermore, the image-receiving layer of control group C1 tended to adhere to the opposite side of the thermal image receiver element, especially when it was in roll form or in a slice stack.

Comparison of control C1 (without release agent) with control C2 (with release agent) shows that the presence of a water-dispersible release agent in the image receiving layer formulation reduces the adhesion of the donor element to the thermal image receiver element during the thermal printing process.

When a crosslinker is present in the dye image receiving layer formulation, the donor-receiver adhesion problem (improved donor-receiver release characteristics) is reduced so that less release agent is required in the image receiving layer, which in turn helps promote improved adhesion between the clear laminate protective film and the image receiving layer, which is a desirable characteristic.

TABLE III

"NA" means that data is not available due to donor-receiver adhesion.

*Is/are as followsMD-1480。

Claims (20)

1. A conductive thermal image receiver element comprising a support and having on at least one side of the support:

an aqueous coatable receiver overcoat layer and an aqueous coatable dye-receiving layer,

wherein the aqueous coatable receiver overcoat layer comprises a conductive polymeric material, a first dispersant and a second dispersant,

wherein the first dispersant and the second dispersant are independently selected from the group consisting of: (a) a random copolymer; and (b) an acrylic block copolymer; and is

Wherein the aqueous coatable dye-receiving layer comprises a water-dispersible release agent, a crosslinking agent, and a polymeric binder matrix consisting essentially of:

(1) a water-dispersible acrylic polymer comprising chemically reacted or chemically non-reacted hydroxyl, phosphonate, sulfonate, carboxyl, or carboxylate groups; and

(2) having a T of 30 ℃ or less_gThe water-dispersible polyester of (1);

wherein the water-dispersible acrylic polymer is present in an amount of at least 55 wt% of the total weight of the aqueous coatable dye-receiving layer and is present in a dry ratio to the water-dispersible polyester of at least 1: 1.

2. The conductive thermal image receiver element of claim 1, wherein the acrylic block copolymer is an acrylic block terpolymer.

3. The conductive thermal image receiver element of claim 1 or 2, wherein (a) the random copolymer and (b) the acrylic block copolymer all comprise a hydrophilic component and a hydrophobic component.

4. The conductive thermal image receiver element of claim 3, wherein the hydrophobic component of each of (a) the random copolymer and (b) the acrylic block copolymer is independently selected from the group consisting of: aliphatic monomers, aromatic monomers, cycloaliphatic monomers, aromatic heterocycles, cycloaliphatic heterocycles, and polycyclic monomers.

5. The conductive thermal image receiver element of claim 3, wherein (a) the random copolymer and (b) the acrylic block copolymer all have a weight average molecular weight ranging from 5,000 to 100,000.

6. The conductive thermal image receiver element of claim 1, wherein the first dispersant is a random copolymer comprising benzyl methacrylate and methacrylic acid.

7. The conductive thermal image receiver element of claim 6, wherein the first dispersant is present in an amount ranging from 1% to 4% by weight, based on the total dry weight of the receiver overcoat layer.

8. The conductive thermal image receiver element of claim 6, wherein the second dispersant is an acrylic block copolymer.

9. The conductive thermal image receiver element of claim 8, wherein the second dispersant is present in an amount ranging from 1% to 4% by weight, based on the total dry weight of the receiver overcoat layer.

10. The conductive thermal image receiver element of claim 6, wherein the second dispersant is an acrylic block terpolymer.

11. The conductive thermal image receiver element of claim 10, wherein the second dispersant is present in an amount ranging from 1% to 4% by weight, based on the total dry weight of the receiver overcoat layer.

12. The conductive thermal image receiver element of claim 1, wherein the first dispersant and the second dispersant are cumulatively present in an amount ranging from 0.5 to 10 wt% based on the total dry weight of the receiver overcoat layer.

13. The conductive thermal image receiver element of claim 1, wherein the receiver overcoat layer further comprises at least one surfactant.

14. The conductive thermal image receiver element of claim 13, wherein the at least one surfactant comprises P-isononylphenoxy poly (glycidol).

15. The conductive thermal image receiver element of claim 1, wherein the conductive polymeric material is poly (3, 4-ethylenedioxythiophene) -poly (styrenesulfonate).

16. The conductive thermal image receiver element of claim 1, wherein the thickness of the receiver overcoat layer ranges from 0.1 μ ι η to 0.62 μ ι η.

17. The conductive thermal image receiver element of claim 1, wherein the first dispersant or the second dispersant is a random terpolymer of benzyl methacrylate, stearyl methacrylate, and methacrylic acid in an amount ranging from 1% to 4% by weight based on the total dry weight of the receiver overcoat layer.

18. A method of making the conductive thermal image receiver element of claim 1, comprising:

(A) applying an aqueous coatable dye-receiving layer formulation to one or both opposing sides of a support or another layer residing on one or both sides of the support, the aqueous coatable dye-receiving layer formulation comprising a water-dispersible release agent, a crosslinking agent, and a polymeric binder matrix consisting essentially of:

(1) a water-dispersible acrylic polymer comprising chemically reacted or chemically non-reacted hydroxyl, phosphonate, sulfonate, carboxyl or carboxylate groups, and

(2) having a T of 30 ℃ or less_gThe water-dispersible polyester of (1);

wherein the water-dispersible acrylic polymer is present in an amount of at least 55 wt% of the resulting total dry weight of the aqueous coatable dye-receiving layer formulation and is present in the polymeric binder matrix at a dry ratio to the water-dispersible polyester of 1:1 to 9.2:1, inclusive, or 4:1 to 20:1, inclusive;

(B) drying the aqueous coatable dye-receiving layer formulation to form an aqueous coatable dye-receiving layer on one or both opposing sides of the support;

(C) applying an aqueous coatable receiver overcoat formulation onto at least one side of a support coated with an aqueous coatable dye-receiving layer, the aqueous coatable receiver overcoat formulation comprising a first dispersant, a second dispersant, and an electrically conductive polymeric material, wherein the first dispersant and the second dispersant are independently selected from the group consisting of: (a) a random copolymer; and (b) an acrylic block copolymer; and

(D) drying the aqueous coatable receiver overcoat formulation to form an aqueous coatable receiver overcoat on one or both opposing sides of the support.

19. The method of claim 18, wherein the same aqueous coatable dye-receiving layer formulation and the same receiver overcoat layer are applied to two opposing sides of the support.

20. The method of claim 18, wherein the acrylic block copolymer is an acrylic block terpolymer.