WO2020072150A1

WO2020072150A1 - Heat transfer printing

Info

Publication number: WO2020072150A1
Application number: PCT/US2019/048821
Authority: WO
Inventors: Inna Tzomik; Dima Libster; Katty NOORANY
Original assignee: Hewlett Packard Development Co LP
Current assignee: Hewlett Packard Development Co LP
Priority date: 2018-10-03
Filing date: 2019-08-29
Publication date: 2020-04-09
Anticipated expiration: 2021-04-03
Also published as: EP3774370A4; US20210245538A1; CN112118964A; US11442393B2; EP3774370B1; US20210240123A1; EP3774370A1; WO2020072054A1

Abstract

Described herein is process for heat transfer printing, the process comprising: liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; and contacting the printed film with a target substrate under conditions such that the printed film adheres to the target substrate. Also described herein is a process for printing a heat transferable printed image and a heat transferable printed image.

Description

Heat Transfer Printing

Heat transfer printing (also known as thermal transfer printing) is the process of transferring images from one substrate to another by the application of heat. The image may first be applied to a first substrate, for example, a polymeric film, this image is then brought into contact with a target substrate, for example, a metallic film, glass or fabric, and heated. The target substrate and the first substrate may then be separated, leaving the image (in reverse) on the target substrate.

Brief Description of the Figures

Figures 1A, 1 B and 1 C show, schematically, an example of a process for heat transfer printing as disclosed herein.

Figure 2 shows dynamic mechanical analysis for the thermoplastic resin of a liquid electrostatic ink composition.

Figure 3 shows dynamic mechanical analysis for polyether-based polyurethane film A (Example 1).

Figure 4 shows dynamic mechanical analysis for polyether-based polyurethane film C (Reference Example 2).

Figure 5 shows ATR-FTIR spectra of thermoplastic polyurethane films A (LB-GH-154, Example 1), B (N-85, Reference Example 1) and C (C-1 , Reference Example 2) in the range of 1600 cm ¹ to 1900 cm ¹.

Detailed Description

Before the heat transfer printing and related aspects are disclosed and described, it is to be understood that this disclosure is not limited to the particular process steps and materials disclosed herein because such process steps and materials may vary somewhat. It is also to be understood that the terminology used herein is used for the purpose of describing particular examples only. The terms are not intended to be limiting because the scope of the present disclosure is intended to be limited by the appended claims and equivalents thereof.

It is noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

As used herein,“liquid carrier”, "carrier liquid," "carrier," or "carrier vehicle" refers to the fluid in which the polymers, particles, colorant, charge directors and other additives can be dispersed to form a liquid electrostatic composition or electrophotographic composition. Such carrier liquids and vehicle components are known in the art. Typical carrier liquids can include a mixture of a variety of different agents, such as surfactants, co-solvents, viscosity modifiers, and/or other possible ingredients.

As used herein, "electrostatic ink composition" generally refers to an ink composition that is typically suitable for use in an electrostatic printing process, sometimes termed an electrophotographic printing process. The electrostatic ink composition, when printing, may include chargeable particles of the resin and, if present, the pigment dispersed in a liquid carrier, which may be as described herein. An electrostatic ink composition for forming an image layer may contain a colorant. A colorant may be a species that imparts a colour to the ink, e.g. a colour selected from a cyan, magenta, yellow and black.

As used herein, "copolymer" refers to a polymer that is polymerized from at least two monomers.

A certain monomer may be described herein as constituting a certain weight percentage of a polymer. This indicates that the repeating units formed from the said monomer in the polymer constitute said weight percentage of the polymer.

Softening temperatures/softening points referred to herein may be measured according to standard techniques. For example, the softening point/temperature may be as measured by dynamic mechanical analysis according to ASTM E1953 at a temperature ramp of 3°C/min and a constant frequency of 1 Hz, or the Vicat softening point/temperature as measured according to ASTM D152, or the Ring and Ball softening point/temperature as determined according to ASTM E28-99.

If a standard test is mentioned herein, unless otherwise stated, the version of the test to be referred to is the most recent at the time of filing this patent application.

As used herein,“electrostatic printing” or "electrophotographic printing" generally refers to the process that provides an image that is transferred from a photo imaging substrate either directly, or indirectly via an intermediate transfer member, to a print substrate. As such, the image is not substantially absorbed into the photo imaging substrate on which it is applied. Additionally, "electrophotographic printers" or “electrostatic printers” generally refer to those printers capable of performing electrophotographic printing or electrostatic printing, as described above. "Liquid electrophotographic printing" is a specific type of electrophotographic printing where a liquid composition is employed in the electrophotographic process rather than a powder toner. An electrostatic printing process may involve subjecting the electrostatic composition to an electric field, e.g. an electric field having a field gradient of 1000 V/cm or more, or in some examples 1500 V/cm or more.

As used herein, the term "about" is used to provide flexibility to a numerical range endpoint by providing that a given value may be "a little above" or "a little below" the endpoint. The degree of flexibility of this term can be dictated by the particular variable and would be within the knowledge of those skilled in the art to determine based on experience and the associated description herein.

As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary.

Concentrations, amounts, and other numerical data may be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. As an illustration, a numerical range of "about 1 wt.% to about 5 wt.%" should be interpreted to include not only the explicitly recited values of about 1 wt.% to about 5 wt.%, but also include individual values and subranges within the indicated range. Thus, included in this numerical range are individual values such as 2, 3.5, and 4 and sub-ranges such as from 1-3, from 2-4, and from 3-5, etc. This same principle applies to ranges reciting only one numerical value. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described.

Unless otherwise stated, any feature described herein can be combined with any aspect or any other feature described herein.

In an aspect, there is provided a process for heat transfer printing. The process for heat transfer printing may comprise:

liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; and contacting the printed film with a target substrate under conditions such that the printed film adheres to the target substrate.

The process for heat transfer printing may comprise:

liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; and contacting the printed film with a target substrate under conditions such that the printed film adheres to the target substrate;

wherein the lower limit of the melting range of the polyether-based thermoplastic polyurethane film is in the range of 70°C to 90°C.

The process for heat transfer printing may comprise:

liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; and contacting the printed film with a target substrate under conditions such that the printed film adheres to the target substrate; wherein the softening point of the polyether-based thermoplastic polyurethane film is in the range of 70°C to 80°C.

In another aspect, there is provided a process for printing a heat transferable image. The process for printing a heat transferable image may comprise:

liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film.

The process for printing a heat transferable image may comprise:

liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film;

The process for printing a heat transferable image may comprise:

wherein the softening point of the polyether-based thermoplastic polyurethane film is in the range of 70°C to 80°C.

In a further aspect, there is provided a heat transferable printed image. The heat transferable printed image may comprise:

a polyether-based thermoplastic polyurethane film; and

a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film.

The heat transferable printed image may comprise:

a polyether-based thermoplastic polyurethane film;

a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film;

The heat transferable printed image may comprise:

a polyether-based thermoplastic polyurethane film; a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film; and

There is also described herein a heat transfer printed substrate. The heat transfer printed substrate may comprise:

a target substrate, for example, a fabric;

a printed film disposed on the target substrate, the printed film comprising a liquid electrostatically printed ink disposed on a polyether-based thermoplastic polyurethane film.

The heat transfer printed substrate may comprise:

a target substrate, for example, a fabric;

a printed film disposed on the target substrate, the printed film comprising a liquid electrostatically printed ink disposed on a polyether-based thermoplastic polyurethane film;

The heat transfer printed substrate may comprise:

a target substrate, for example, a fabric;

There is also described herein a process for heat transfer printing comprising:

wherein the polyether-based thermoplastic polyurethane film comprises a copolymer of: a polyisocyanate;

a polyether polyol;

and a chain extender, wherein the chain extender comprises a diamine, an aminoalcohol or a mixture thereof.

There is also described herein a process for printing a heat transferable image comprising:

wherein the polyether-based thermoplastic polyurethane film comprises a copolymer of:

a polyisocyanate;

a polyether polyol; and

a chain extender, wherein the chain extender comprises a diamine, an aminoalcohol or a mixture thereof.

There is also described herein a heat transferable printed image comprising:

a polyether-based thermoplastic polyurethane film; and

a polyisocyanate;

a polyether polyol; and

There is also described herein, a heat transfer printed substrate comprising:

a target substrate, for example, a fabric;

a polyisocyanate; a polyether polyol; and

Heat transfer printing is used in a variety of products, for example, the production of printed fabrics. It is therefore desirable to produce such printed products in as few steps as possible. Moreover, ink compositions must adhere well to the fabric and remain adhered to the fabric even after several washing and drying cycles. Examples of the methods and products described herein have been found to avoid or at least mitigate at least one of these difficulties. It has been found that example thermoplastic polyurethane films can be printed directly on and used in heat transfer printing to adhere printed images to target substrates, such as fabric. The electrostatic ink compositions adhere well to the target substrates and remain adhered even after several washing and drying cycles.

Figure 1A, 1 B and 1 C show, schematically, an example of a process for heat transfer printing, as disclosed herein. Figure 1A shows a heat transferable printed image comprising a polyether-based thermoplastic polyurethane film 1 ; and a liquid electrostatically printed ink 2 disposed on the polyether-based thermoplastic polyurethane film 1 to form a printed film 8. In some examples, a support layer 4 is disposed on the opposing side of the polyether-based thermoplastic polyurethane film 1 to the liquid electrostatically printed ink 2. In some examples, a protective layer 3 is contacted with the liquid electrostatically printed ink 2.

In Figure 1 B (left), the target substrate 5 has been brought into contact with the liquid electrostatically printed ink 2 disposed on the polyether-based thermoplastic film 1 and, after conditions such that printed film 8 adheres to the target substrate have been applied, heat transfer printed substrate 10 is formed. If present, the support layer 4 may remain during heat transfer printing but the protective layer 3, if present, is removed before heat transfer printing. In Figure 1 B (right), the target substrate 5 has been brought into contact with the polyether-based thermoplastic polyurethane film 1 film and, after conditions such that printed film 8 adheres to the target substrate have been applied, heat transfer printed substrate 10 is formed. If present, the protective layer 3 may remain during heat transfer printing but the support layer 4, if present, is removed before heat transfer printing. Figure 1 C shows, schematically, the two possible heat transfer printed substrates 10, that is, a heat transfer printed substrate 10 in which the liquid electrostatically printed ink 2 contacts the target substrate 5 (left) and a heat transfer printed substrate 10 in which the polyether-based thermoplastic polyurethane film 1 contacts the target substrate (right).

Heat transfer printing

The process for heat transfer printing may comprise liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; and contacting the printed film with a target substrate under conditions such that the printed film adheres to the target substrate. In some examples, the lower limit of the melting range of the polyether-based polyurethane film may be in the range of 70°C to 90°C. In some examples, the softening point of the polyether- based thermoplastic polyurethane film may be in the range of 70°C to 80°C. In some examples, the polyether-based thermoplastic polyurethane film may comprise a copolymer of a polyisocyanate; a polyether polyol; and a chain extender, wherein the chain extender comprises a diamine, an aminoalcohol or a mixture thereof.

The melting range of a polymer is determined by using dynamic mechanical analysis (measured according to ASTM E1953 at a temperature ramp of 3°C/min and a constant frequency of 1 Hz).

The melting of the polymer may be seen in dynamic mechanical analysis by a sharp increase in tan d. In some examples, the lower limit of the melting range of the polymer may be the temperature at which the gradient of the graph of tan d against temperature increases. In some examples, the upper limit of the melting range of the polymer may be the temperature at which tan d is about 1. In some examples, the upper limit of the melting range is within the range specified for the lower limit of the melting range. In some examples, the upper limit of the melting range is above the range specified for the lower limit of the melting range.

The softening point of a polymer is the temperature at which the polymer transitions from being stiff to being soft. This transition can be determined by measuring the tan d using dynamic mechanical analysis (measured according to ASTM E1953 at a temperature ramp of 3°C/min and a constant frequency of 1 Hz) and may be the temperature at which tan d rises above 0.1 and above which a sharp rise in tan d occurs.

In some examples, the softening point may be the Vicat softening point measured under ASTM D1525. In some examples, the polyether-based thermoplastic polyurethane film may melt (for example, begin to melt) too quickly to measure the Vicat softening point, in which case, the melting (for example, the lower limit of the melting range) of the polyether-based thermoplastic polyurethane film occurs at a temperature within the range given for the Vicat softening point.

In some examples, the process for heat transfer printing comprises: liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; and contacting the printed film with a target substrate under conditions such that the printed film adheres to the target substrate, wherein the lower limit of the melting range of the polyether-based thermoplastic polyurethane film is in the range of 70°C to 90°C.

In some examples, the process for heat transfer printing comprises: liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; and contacting the printed film with a target substrate under conditions such that the printed film adheres to the target substrate; wherein the softening point of the polyether-based thermoplastic polyurethane film is in the range of 70°C to 80°C.

In some examples, the process for heat transfer printing comprises: liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; and contacting the printed film with a target substrate under conditions such that the printed film adheres to the target substrate; wherein the polyether-based thermoplastic polyurethane film comprises a copolymer of a polyisocyanate; a polyether polyol; and a chain extender, wherein the chain extender comprises a diamine, an aminoalcohol or a mixture thereof. In some examples, the process for heat transfer printing comprises: liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; and contacting the printed film with a target substrate under conditions such that the printed film adheres to the target substrate; wherein the lower limit of the melting range of the polyether-based thermoplastic polyurethane film is in the range of 70°C to 90°C; and wherein the polyether-based thermoplastic polyurethane film comprises a copolymer of a polyisocyanate; a polyether polyol; and a chain extender, wherein the chain extender comprises a diamine, an aminoalcohol or a mixture thereof.

In some examples, the process for heat transfer printing comprises: liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; and contacting the printed film with a target substrate under conditions such that the printed film adheres to the target substrate; wherein the softening point of the polyether-based thermoplastic polyurethane film is in the range of 70°C to 80°C; and wherein the polyether-based thermoplastic polyurethane film comprises a copolymer of a polyisocyanate; a polyether polyol; and a chain extender, wherein the chain extender comprises a diamine, an aminoalcohol or a mixture thereof.

In some examples, contacting the printed film with the target substrate comprises contacting the polyether-based thermoplastic polyurethane film with the target substrate. In some examples, contacting the printed film with the target substrate comprises contacting the liquid electrostatically printed ink with the target substrate.

In some examples, the process for heat transfer printing comprises liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; and contacting the polyether- based thermoplastic polyurethane film of the printed film with a target substrate under conditions such that the printed film adheres to the target substrate.

In some examples, the process for heat transfer printing comprises liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; and contacting the liquid electrostatically printed ink of the printed film with a target substrate under conditions such that the printed film adheres to the target substrate.

In some examples, the polyether-based thermoplastic polyurethane film comprises a support layer. In some examples, the support layer is removed before the printed film is contacted with the target substrate. In some examples, the support layer is removed after the printed film is contacted with the target substrate. In some examples, the support layer is removed from the printed film and the polyether-based polyurethane film is contacted with the target substrate. In some examples, the liquid electrostatically printed ink is contacted with the target substrate and the support layer is removed after the printed film is contacted with the target substrate.

In some examples, the process for heat transfer printing comprises liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; contacting a protective layer with the liquid electrostatically printed ink of the printed film; and contacting the printed film with a target substrate under conditions such that the printed film adheres to the target substrate. In some examples, the protective layer is removed after the printed film has adhered to the target substrate. In some examples, the protective layer is removed before the printed film has adhered to the target substrate. In some examples, the polyether-based thermoplastic polyurethane film of the printed film is contacted with the target substrate under conditions such that the printed film adheres to the target substrate and the protective layer is removed after the printed film has adhered to the target substrate.

In some examples, the printed film adheres to the target substrate when the layer in contact with the target substrate softens. In some examples, the printed film adheres to the target substrate when the layer in contact with the target substrate melts. In some examples, the printed film adheres to the target substrate when the layer in contact with the target substrate is heated at or above the lower limit of the melting range of the layer. In some examples, the layer in contact with the target substrate may be the polyether-based thermoplastic polyurethane film. In some examples, the layer in contact with the target substrate may be the liquid electrostatically printed ink. In some examples, the conditions required to adhere the printed film to the target substrate may involve the application of heat. In some examples, the conditions required to adhere the printed film to the target substrate may involve the application of pressure. In some examples, the conditions required to adhere the printed film to the target substrate may involve heat and pressure.

In some examples, the polyether-based thermoplastic polyurethane film adheres to the target substrate when the polyether-based thermoplastic polyurethane film is softened. In some examples, the polyether-based thermoplastic polyurethane film adheres to the target substrate when the polyether-based thermoplastic polyurethane film is melted. In some examples, the polyether-based thermoplastic polyurethane film adheres to the target substrate when the polyether-based thermoplastic polyurethane film is heated at or above the lower limit of the melting range of the polyether-based thermoplastic polyurethane film.

In some examples, the liquid electrostatically printed ink adheres to the target substrate when the liquid electrostatically printed ink, for example, the resin therein, is softened. In some examples, the liquid electrostatically printed ink adheres to the target substrate when the liquid electrostatically printed ink, for example, the resin therein, is melted. In some examples, the liquid electrostatically printed ink adheres to the target substrate when the liquid electrostatically printed ink, for example, the resin therein, is heated at or above the lower limit of the melting range of the liquid electrostatically printed ink, for example, the resin therein.

In some examples, contacting the printed film with the target substrate under conditions such that the printed film adheres to the target substrate comprises softening the polyether-based thermoplastic polyurethane film. In some examples, contacting the printed film with the target substrate under conditions such that the printed film adheres to the target substrate comprises softening the liquid electrostatically printed ink. In some examples, contacting the printed film with the target substrate under conditions such that the printed film adherers to the target substrate comprises softening the polyether-based thermoplastic polyurethane film and softening the liquid electrostatically printed ink. In some examples, contacting the printed film with the target substrate under conditions such that the printed film adheres to the target substrate comprises melting (e.g., partially melting) the polyether-based thermoplastic polyurethane film (e.g., heating to above the lower limit of the melting range of the polyether-based thermoplastic polyurethane film). In some examples, contacting the printed film with the target substrate under conditions such that the printed film adheres to the target substrate comprises melting (e.g., partially melting) the liquid electrostatically printed ink (e.g., heating to above the lower limit of the melting range of the liquid electrostatically printed ink). In some examples, contacting the printed film with the target substrate under conditions such that the printed film adheres to the target substrate comprises softening the polyether-based thermoplastic polyurethane film and melting (e.g., partially melting) the liquid electrostatically printed ink (e.g., heating to above the lower limit of the melting range of the liquid electrostatically printed ink). In some examples, contacting the printed film with the target substrate under conditions such that the printed film adheres to the target substrate comprises melting (e.g., partially melting) the polyether-based thermoplastic polyurethane film (e.g., heating to above the lower limit of the melting range of the polyether-based thermoplastic polyurethane film) and softening the liquid electrostatically printed ink. In some examples, contacting the printed film with the target substrate under conditions such that the printed film adheres to the target substrate comprises melting (e.g., partially melting) the polyether-based thermoplastic polyurethane film (e.g., heating to above the lower limit of the melting range of the polyether-based thermoplastic polyurethane film) and melting (e.g., partially melting) the liquid electrostatically printed ink (e.g., heating to above the lower limit of the melting range of the liquid electrostatically printed ink). In some examples, partially melting indicates heating to a temperature that is at or above the lower limit of the melting range but below the upper limit of the melting range.

In some examples, softening the liquid electrostatically printed ink comprises softening the resin or resins of the liquid electrostatically printed ink. In some examples, melting the liquid electrostatically printed ink comprises melting the resin or resins of the liquid electrostatically printed ink.

In some examples, the softening or melting is achieved by the application of heat. In some examples, the softening or melting is achieved by the application of heat and pressure. In some examples, contacting the printed film with the target substrate under conditions such that the printed film adheres to the target substrate may be carried out at a suitable temperature to allow the polyether-based thermoplastic polyurethane film to soften or become molten (or at least partially molten) during the contacting of the printed film with the target substrate. In some examples, contacting the printed film with the target substrate under conditions such that the printed film adheres to the target substrate may be carried out at a suitable temperature to allow the liquid electrostatically printed ink to soften or become molten (or at least partially molten) during the contacting of the printed film with the target substrate. In some examples, contacting the printed film with the target substrate under conditions such that the printed film adheres to the target substrate may be carried out at a suitable temperature to allow the polyether-based thermoplastic polyurethane film and the liquid electrostatically printed ink to soften or become molten (or at least partially molten) during the contacting of the printed film with the target substrate. The suitable temperature may be a raised temperature, for example, of 30°C or above, in some examples, 40°C or above, 50°C or above, 60°C or above, 70°C or above, 80°C or above, 85°C or above, 90°C or above, 100°C or above, 1 10°C or above, 120°C or above, 130°C or above, 140°C or above, 150°C or above, 160°C or above, 180°C or above, 190°C or above, 200°C or above, 210°C or above, 220°C or above, 230°C or above, 240°C or above or 250°C or above. The suitable temperature may be from 30°C to 300°C, in some examples 30°C to 250°C, in some examples 30°C to 240°C, in some examples 40°C to 230°C, in some example, 50°C to 220°C, in some examples, 60°C to 210°C. The suitable temperature may be from 100°C to 250°C, in some examples from 1 10°C to 220°C, in some examples from 120°C to 210°C, in some examples from 130°C to 200°C, in some examples from 140°C to 300°C, in some examples, 150°C to 200°C. In some examples, at least partially molten indicates that heating has occurred to a temperature that is at or above the lower limit of the melting range but below the upper limit of the melting range.

The suitable temperature may be a temperature within or above the melting range of the layer in contact with the target substrate when the printed film is heated. The suitable temperature may be a temperature at or above the lower limit of the melting range of the layer in contact with the target substrate when the printed film is heated. The suitable temperature may be a temperature at or above the softening point of the layer in contact with the target substrate when the printed film is heated. The suitable temperature may be within or above the melting range of the polyether-based thermoplastic polyurethane film. The suitable temperature may be at or above the lower limit of the melting range of the polyether-based thermoplastic polyurethane. The suitable temperature may be a temperature at or above the softening point of the polyether-based thermoplastic polyurethane film. The suitable temperature may be a temperature within or above the melting range of the liquid electrostatically printed ink (e.g., within or above the melting range of the resins of the liquid electrostatically printed ink). The suitable temperature may be a temperature at or above the lower limit of the melting range of the liquid electrostatically printed ink (e.g., at or above the lower limit of the melting range of the resins of the liquid electrostatically printed ink). The suitable temperature may be a temperature at or above the softening point of the liquid electrostatically printed ink (e.g., at or above the softening point of the resins of the liquid electrostatically printed ink).

In some examples, the printed film may adhere to the target substrate while the layer in contact with the target substrate is softened. In some examples, the liquid electrostatically printed ink may contact the target substrate. In some examples, the polyether-based thermoplastic polyurethane film may contact the target substrate.

In some examples, the conditions such that the printed film adheres to the target substrate comprise heating for 5 mins or less, for example, 1 min or less, 55 s or less, 50 s or less, 45 s or less, 40 s or less, 35 s or less, 30 s or less, 25 s or less, 20 s or less. In some examples, the conditions such that the printed film adheres to the target substrate comprise heating for 1 s or more, for example, 5 s or more, 10 s or more, 15 s or more, 20 s or more, 25 s or more, 30 s or more. In some examples, the conditions such that the printed film adheres to the target substrate comprise heating for from 1 s to 5 mins, for example, 5 s to 1 min, 10 s to 50 s, 15 s to 45 s, 20 s to 30 s.

In some examples, contacting the printed film with a target substrate under conditions such that the printed film adheres to the target substrate may involve pressing the printed film and the target substrate between two members, at least one of which, in some examples, both of which is/are heated, for example, to a temperature mentioned above. In some examples, the two members may be heated to the same temperature, for example, a temperature mentioned above. In some examples, the two members may be heated to different temperatures. In some examples, the two members may be heated to a temperature of 100°C to 300°C, for example, 1 10°C to 250°C, 120°C to 240°C, 130°C to 230°C, 140°C to 220°C, 150°C to 210°C, 150°C to 200°C. In some examples, the two members may be rollers and may be part of a heat transfer printing apparatus or a lamination apparatus. If the two members are rollers, the speed of passing the printed film and the target substrate through the rollers may be any suitable speed to allow the polyether-based thermoplastic polyurethane film to soften, at least partially melt, or melt. If the two members are rollers, the speed of passing the printed film and the target substrate through the rollers may be any suitable speed to allow the liquid electrostatically printed ink to soften, at least partially melt, or melt. If the two members are rollers, the speed of passing the printed film and the target substrate through the rollers may be any suitable speed to allow the polyether-based thermoplastic polyurethane film and the liquid electrostatically printed ink to soften, at least partially melt, or melt. If the two members are rollers, the speed of passing the printed film and the target substrate through the rollers may be any suitable speed to allow the printed film to adhere to the target substrate. If the two members are rollers, the speed of passing the printed film and the target substrate through the rollers may be any suitable speed to allow the liquid electrostatically printed ink to adhere to the target substrate. If the two members are rollers, the speed of passing the printed film and the target substrate through the rollers may be any suitable speed to allow the polyether-based thermoplastic polyurethane film to adhere to the target substrate. The speed may be at least 0.1 m/min, in some examples at least 0.5 m/min, in some examples at least 1 m/min. The speed may be at least 10 m/min or less, in some examples 5 m/min or less, in some examples 4 m/min or less, in some examples 3 m/min or less, in some examples, 2 m/min or less. The speed may be of from 0.1 m/min to 10 m/min, in some examples from 0.5 m/min to 5 m/min, in some examples 0.5 m/min to 4 m/min, in some examples 1 m/min to 3 m/min, in some examples, 0.1 m/min to 1 m/min. The speed may be determined depending on the temperature of the rollers, with a higher temperature leading to faster adhesion of the printed film to the target substrate, allowing for a higher speed, since the contact time can be less.

Pressure may be applied during the contacting of the printed film with the target substrate. The pressure may be a pressure of at least from 1 bar (100 kPa), in some examples at least 2 bar, in some examples from 1 bar to 20 bar, in some examples 2 bar to 10 bar, in some examples 2 bar to 5 bar, in some examples 5 bar to 10 bar. The contacting under a raised temperature and, in some examples, under pressure, may be carried out for a suitable time period to effect adhesion, and the suitable time period may be at least 0.1 seconds, in some examples at least 0.2 seconds, in some examples at least 0.5 seconds, in some examples at least 0.8 seconds, in some examples at least 1 second, in some examples at least 1.2 seconds, in some examples at least 1.5 seconds, in some examples at least 1.8 seconds, in some examples at least 2 seconds. The suitable time period may be from 0.1 seconds to 100 seconds, in some examples, 0.1 seconds to 90 seconds, in some examples, 0.2 seconds to 80 seconds, in some examples, 0.5 seconds to 70 seconds, in some examples, 0.8 seconds to 60 seconds, in some examples, 1 second to 50 seconds, in some examples, 1.2 seconds to 40 seconds, in some examples, 1.5 seconds to 30 seconds, in some examples, 1.8 seconds to 20 seconds, in some examples, 2 seconds to 10 seconds, in some examples 0.5 seconds to 5 seconds. In some examples, the suitable time period may be 5 mins or less, for example, 1 min or less, 55 s or less, 50 s or less, 45 s or less, 40 s or less, 35 s or less, 30 s or less, 25 s or less, 20 s or less. In some examples, the suitable time period may be 1 s or more, for example, 5 s or more, 10 s or more, 15 s or more, 20 s or more, 25 s or more, 30 s or more. In some examples, the suitable time period may be from 1 s to 5 mins, for example, 5 s to 1 min, 10 s to 50 s, 15 s to 45 s, 20 s to 30 s.

In some examples, there is provided a process for printing a heat transferable image. The process may comprise: liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film.

In some examples, the process for printing a heat transferable image may comprise liquid electrostatically printing a liquid electrostatic ink composition on a polyether- based thermoplastic polyurethane film to form a printed film; and contacting a protective layer with the liquid electrostatically printed ink.

In some examples, the process for printing a heat transferable image may comprise liquid electrostatically printing a liquid electrostatic ink composition on a polyether- based thermoplastic polyurethane film to form a printed film; contacting a protective layer with the liquid electrostatically printed ink and removing the protective layer from the liquid electrostatically printed ink.

In some examples, the process for heat transfer printing may comprise liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film to form a printed film; contacting a protective layer with the liquid electrostatically printed ink; removing the protective layer from the liquid electrostatically printed ink; and contacting the liquid electrostatically printed ink with a target substrate under conditions such that the liquid electrostatically printed ink adheres to the target substrate.

In some examples, the process for heat transfer printing may comprise liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film disposed on a support layer to form a printed film; contacting the liquid electrostatically printed composition with a target substrate under conditions such that the liquid electrostatically printed ink adheres to the target substrate; and removing the support layer from the polyether-based thermoplastic polyurethane film.

In some examples, the process for heat transfer printing may comprise liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film disposed on a support layer to form a printed film; removing the support layer; and contacting the polyether-based thermoplastic polyurethane film with a target substrate under conditions such that the polyether- based thermoplastic polyurethane film adheres to the target substrate.

In some examples, the process for heat transfer printing may comprise liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film disposed on a support layer to form a printed film; contacting a protective layer with the liquid electrostatically printed ink; removing the support layer; contacting the polyether-based thermoplastic polyurethane film with a target substrate under conditions such that the polyether-based thermoplastic polyurethane film adheres to the target substrate; and removing the protective layer. In some examples, the process for heat transfer printing may comprise liquid electrostatically printing a liquid electrostatic ink composition on a polyether-based thermoplastic polyurethane film disposed on a support layer to form a printed film; removing the support layer; contacting a protective layer with the liquid electrostatically printed ink; contacting the polyether-based thermoplastic polyurethane film with a target substrate under conditions such that the polyether-based thermoplastic polyurethane film adheres to the target substrate; and removing the protective layer.

Liquid electrostatic printing

Liquid electrostatically printing a liquid electrostatic ink composition on a polyether- based thermoplastic polyurethane film may comprise forming a latent electrostatic image on a surface; contacting the surface with the liquid electrostatic ink composition, such that at least some of the liquid electrostatic ink composition adheres to the surface to form a developed toner image on the surface, and transferring the toner image to a print substrate (i.e., the polyether-based thermoplastic polyurethane film), in some examples, via an intermediate transfer member, to form a printed film. During printing, the liquid electrostatic ink composition may comprise particles, which may be termed toner particles, the particles comprising a thermoplastic resin, and in some examples, a colourant, a charge adjuvant and/or a charge director.

The printed film comprises a liquid electrostatically printed ink disposed on a polyether- based thermoplastic polyurethane film. Once printed, the liquid electrostatic ink composition is referred to herein as a liquid electrostatically printed ink.

The surface on which the latent electrostatic image is formed may be on a rotating member, for example, in the form of a cylinder. The surface on which the latent electrostatic image is formed may form part of a photo imaging plate (PIP). The contacting may involve passing the liquid electrostatic ink composition between a stationary electrode and a rotating member, which may be a member having the surface having a latent image thereon or a member in contact with the surface having a latent electrostatic image thereon. A voltage is applied between the stationary electrode and the rotating member, such that the particles adhere to the surface of the rotating member. This may involve subjecting the liquid electrostatic ink composition to an electric field having a gradient of 50-400 V/pm, or more, in some examples, 600-900 V/pm or more.

The intermediate transfer member may be a rotating flexible member, which is, in some examples, heated, for example, to a temperature of from 80°C to 160°C, in some examples, 90°C to 130°C, in some examples, from 100°C to 1 10°C.

Heat transferable printed image

In some examples, there is provided a heat transferable printed image comprising a polyether-based thermoplastic polyurethane film; and a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film. In some examples, the lower limit of the melting range of the polyether-based thermoplastic polyurethane film is in the range of 70°C to 90°C. In some examples, the softening point of the polyether-based thermoplastic polyurethane film is in the range of 70°C to 80°C. In some examples, the polyether-based thermoplastic polyurethane film comprises a copolymer of a polyisocyanate; a polyether polyol; and a chain extender, wherein the chain extender comprises a diamine, an aminoalcohol or a mixture thereof.

In some examples, the heat transferable printed image may be referred to herein as a printed film. The printed film comprises a liquid electrostatically printed ink disposed on a polyether-based thermoplastic polyurethane film. Once printed, the liquid electrostatic ink composition is referred to herein as a liquid electrostatically printed ink.

In some examples, there is provided a heat transferable printed image comprising a polyether-based thermoplastic polyurethane film; and a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film; wherein the lower limit of the melting range of the polyether-based thermoplastic polyurethane film is in the range of 70°C to 90°C.

In some examples, there is provided a heat transferable printed image comprising a polyether-based thermoplastic polyurethane film; and a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film; wherein the softening point of the polyether-based thermoplastic polyurethane is in the range of 70°C to 80°C. In some examples, there is provided a heat transferable printed image comprising a polyether-based thermoplastic polyurethane film; a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film; wherein the polyether-based thermoplastic polyurethane comprises a copolymer of a polyisocyanate; a polyether polyol; and a chain extender, wherein the chain extender comprises a diamine, an aminoalcohol or a mixture thereof.

In some examples, the heat transferable printed image further comprises a support layer. In some examples, the support layer is disposed on the opposing side of the polyether-based thermoplastic polyurethane film from the liquid electrostatically printed ink. In some examples, the heat transferable printed image comprises a support layer; a polyether-based thermoplastic polyurethane film disposed on the support layer; and a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film.

In some examples, the heat transferable printed image further comprises a protective layer. In some examples, the protective layer is in contact with the opposing side of the liquid electrostatically printed ink from the polyether-based thermoplastic polyurethane film. In some examples, the heat transferable printed image comprises a polyether- based thermoplastic polyurethane film; a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film; and a protective layer in contact with the liquid electrostatically printed ink. In some examples, the heat transferable printed image comprises a support layer; a polyether-based thermoplastic polyurethane film disposed on the support layer; a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film; and a protective layer in contact with the liquid electrostatically printed ink.

In some examples, the heat transferable printed image is formed by the process for printing a heat transferable image.

In some examples, the heat transferable printed image is used in the process for heat transfer printing. In some examples, the process for heat transfer printing comprises contacting the heat transferable printed image with a target substrate under conditions such that the printed film (i.e., the heat transferable printed image) adheres to the target substrate. The conditions used may be the same as those described above.

In some examples, the process for heat transfer printing comprises removing, if present, a support layer from a heat transferable printed image; contacting the polyether-based thermoplastic polyurethane film of the heat transferable printed image with a target substrate under conditions such that the printed film adheres to the target substrate; and removing, if present, a protective layer from the liquid electrostatically printed ink. The conditions used may be the same as those described above.

In some examples, the process for heat transfer printing comprises removing, if present, a protective layer from the heat transferable printed image; contacting the liquid electrostatically printed ink of the heat transferable printed image with a target substrate under conditions such that the printed film adheres to the target substrate; and removing, if present, a support layer from the heat transferable printed image. The conditions used may be the same as those described above.

In some examples, the heat transferable printed image consists of a polyether-based thermoplastic polyurethane film; and a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film. In some examples, the heat transferable printed image consists of a support layer; a polyether-based thermoplastic polyurethane film disposed on the support layer; and a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film. In some examples, the heat transferable printed image consists of a polyether-based thermoplastic polyurethane film; a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film; and a protective layer in contact with the liquid electrostatically printed ink. In some examples, the heat transferable printed image consists of a support layer; a polyether-based thermoplastic polyurethane film disposed on the support layer; a liquid electrostatically printed ink disposed on the polyether-based thermoplastic polyurethane film; and a protective layer in contact with the liquid electrostatically printed ink.

In some examples, the polyether-based thermoplastic polyurethane film consists of a monolayer polyether-based thermoplastic polyurethane film. Heat transfer printed substrate

In some examples, there is provided a heat transfer printed substrate comprising a target substrate; and a printed film disposed on the target substrate, the printed film comprising a liquid electrostatically printed ink disposed on a polyether-based thermoplastic polyurethane film.

In some examples, there is provided a heat transfer printed substrate comprising a target substrate; a liquid electrostatically printed ink disposed on the target substrate; and a polyether-based thermoplastic polyurethane film disposed on the liquid electrostatically printed ink.

In some examples, there is provided a heat transfer printed substrate comprising a target substrate; a polyether-based thermoplastic polyurethane film disposed on the target substrate; and a liquid electrostatically printed ink disposed on the polyether- based thermoplastic polyurethane film.

In some examples, the target substrate comprises a fabric.

Polyether-based thermoplastic polyurethane

In some examples, the lower limit of the melting range of the polyether-based thermoplastic polyurethane film may be in the range of 70°C to 90°C, for example, 71 °C to 90°C, 72°C to 89°C, 73°C to 88°C, 74°C to 87°C, 75°C to 86°C, 76°C to 85°C, 77°C to 84°C, 78°C to 83°C, 79°C to 82°C, or 80°C to 81 °C.

In some examples, the polyether-based thermoplastic polyurethane film may have a softening point in the range of 70°C to 90°C, for example, 71 °C to 89°C, 72°C to 88°C, 73°C to 87°C, 74°C to 86°C, 75°C to 85°C, 76°C to 84°C, 75°C to 83°C, 80°C to 82°C, 71 °C to 81 °C.

In some examples, the melting range of the polyether-based thermoplastic polyurethane film may be similar to the melting range of the resins of the liquid electrostatic ink composition. In some examples, the lower limit of the melting range of the polyether-based thermoplastic polyurethane film may be similar to the lower limit of the melting range of the resins of the liquid electrostatic ink composition. In some examples, the melting range of the polyether-based thermoplastic polyurethane film may be within 30°C of the melting range of the resins of the liquid electrostatic ink composition. In some examples, the lower limit of the melting range of the polyether- based thermoplastic polyurethane film may be within 30°C of the lower limit of the melting range of the resins of the liquid electrostatic ink composition. In some examples, the melting range (e.g., the lower limit of the melting range) of the polyether- based thermoplastic polyurethane film may be no more than 30°C higher than the melting range (e.g., the lower limit of the melting range) of the resins of the liquid electrostatic ink composition, for example, no more than 25°C higher, no more than 20°C higher, no more than 15°C higher, no more than 10°C higher than the melting range of the liquid electrostatic ink composition. In some examples, the melting range (e.g., the lower limit of the melting range) of the polyether-based thermoplastic polyurethane may be equal to or higher than the melting range (e.g., the lower limit of the melting range) of the liquid electrostatic ink composition. In some examples, the melting range (e.g., the lower limit of the melting range) of the polyether-based thermoplastic polyurethane may be no more than 10°C lower than the melting range (e.g., the lower limit of the melting range) of the resins of the liquid electrostatic ink composition, for example, no more than 5°C lower, no more than 4°C lower, no more than 3°C lower, no more than 2°C lower, no more than 1 °C lower than the melting range (e.g., the lower limit of the melting range) of the resins of the liquid electrostatic ink composition. The melting range (e.g., the lower limit of the melting range) of the resins of the liquid electrostatic ink composition may be the melting range (e.g., the lower limit of the melting range) of a mixture of resins.

In some examples, the softening point of the polyether-based thermoplastic polyurethane film may be within 30°C of the softening point of the resins of the liquid electrostatic ink composition. In some examples, the softening point of the polyether- based thermoplastic polyurethane film may be no more than 30°C higher than the softening point of the resins of the liquid electrostatic ink composition, for example, no more than 25°C higher, no more than 20°C higher, no more than 15°C higher, no more than 10°C higher than the softening point of the resins of the liquid electrostatic ink composition. In some examples, the softening point of the polyether-based thermoplastic polyurethane may be equal to or higher than the softening point of the liquid electrostatic ink composition. In some examples, the softening point of the polyether-based thermoplastic polyurethane may be no more than 5°C lower than the softening point of the resins of the liquid electrostatic ink composition, for example, no more than 4°C lower, no more than 3°C lower, no more than 2°C lower, no more than 1 °C lower than the softening point of the resins of the liquid electrostatic ink composition. The softening point of the resins of the liquid electrostatic ink composition may be the softening point of a mixture of resins.

The polyether-based thermoplastic polyurethane film may have a thickness of 35 pm or more, 40 pm or more, 45 pm or more, 50 pm or more, for example, 60 pm or more, 70 pm or more, 80 pm or more, 90 pm or more, 100 pm or more, 1 10 pm or more, 120 pm or more, 130 pm or more, 140 pm or more, 150 pm or more, 160 pm or more, 170 pm or more, 180 pm or more, 190 pm or more, 200 pm or more, 210 pm or more, 220 pm or more, 230 pm or more, 240 pm or more, 250 pm or more, 260 pm or more, 270 pm or more, 280 pm or more, 290 pm or more, 300 pm or more. The polyether-based thermoplastic polyurethane film may have a thickness of 300 pm or less, for example, 290 pm or less, 280 pm or less, 270 pm or less, 260 pm or less, 250 pm or less, 240 pm or less, 230 pm or less, 220 pm or less, 210 pm or less, 200 pm or less, 190 pm or less, 180 pm or less, 170 pm or less, 160 pm or less, 150 pm or less, 140 pm or less, 130 pm or less, 120 pm or less, 1 10 pm or less, 100 pm or less, 90 pm or less, 80 pm or less, 70 pm or less, 60 pm or less, 50 pm or less, 45 pm or less, 40 pm or less, 35 pm or less. The polyether-based thermoplastic polyurethane film may have a thickness of 35 pm to 300 pm, for example, 40 pm to 290 pm, 45 pm to 280 pm, 50 pm to 270 pm, 60 pm to 260 pm, 70 pm to 250 pm, 80 pm to 240 pm, 90 pm to 230 pm, 100 pm to 220 pm, 50 pm to 210 pm, 60 pm to 200 pm, 70 pm to 190 pm, 80 pm to 180 pm, 90 pm to 100 pm, 100 pm to 160 pm, 50 pm to 150 pm, 60 pm to 140 pm, 70 pm to 130 pm, 80 pm to 120 pm, 90 pm to 1 10 pm, 50 pm to 100 pm. In some examples, the polyether-based thermoplastic polyurethane film may have a thickness of about 100 pm.

In some examples, the polyether-based thermoplastic polyurethane film may comprise one or more layers of material. In some examples, the polyether-based thermoplastic polyurethane film may comprise one layer of material, that is, be a monolayer film. If the polyether-based thermoplastic polyurethane film comprises more than one layer of material, the lower limit of the melting range or the softening point described herein is the lower limit of the melting range or the softening point of the layer onto which the liquid electrostatic ink composition is printed.

In some examples, the lower limit of the melting range of the polyether-based thermoplastic polyurethane may be 90°C or less, for example, 89°C or less, 88°C or less, 87°C or less, 86°C or less, 85°C or less, 84°C or less, 83°C or less, 82°C or less, 81 °C or less, 80°C or less, 79°C or less, 78°C or less, 77°C or less, 76°C or less, 75°C or less, 74°C or less, 73°C or less, 72°C or less, 71 °C or less, 70°C or less. In some examples, the lower limit of the melting range of the polyether-based thermoplastic polyurethane film may be 70°C or more, 71 °C or more, 72°C or more, 73°C or more 74°C or more, 75°C or more, 76°C or more, 77°C or more, 78°C or more, 79°C or more, 80°C or more, 81 °C or more, 82°C or more, 83°C or more, 84°C or more, 85°C or more, 86°C or more, 87°C or more, 88°C or more, 89°C or more, 90°C or more. In some examples, the lower limit of the melting range of the polyether-based thermoplastic polyurethane film may be 70°C to 90°C, 71 °C to 89°C, 72°C to 88°C, 73°C to 87°C, 74°C to 86°C, 75°C to 85°C, 76°C to 84°C, 77°C to 83°C, 78°C to 82°C, 79°C to 81 °C, 70°C to 80°C. In some examples, the melting range is measured by dynamic mechanical analysis according to ASTM E1953 at a temperature ramp of 3°C/min and a constant frequency of 1 Hz. In some examples, the lower limit of the melting range is higher than the softening point.

Thermoplastic polyurethanes are a class of polyurethanes comprising linear segmented block co-polymers, which may have hard and soft segments. Thermoplastic polyurethane polymers may be formed by the reaction of three components: polyisocyanates, polyols, and so-called chain extenders. In a polyether-based thermoplastic polyurethane, the polyol comprises or consists of a polyether polyol. In some examples, the so-called chain extender may comprise a diamine, an aminoalcohol, a diol or a combination thereof. In some examples, the chain extender comprises a diamine and/or an aminoalcohol.

In some examples, the polyether-based thermoplastic polyurethane comprises a copolymer of a polyisocyanate, a polyether polyol; and a chain extender, wherein the chain extender comprises a diamine, an aminoalcohol or a mixture thereof. In some examples, the polyisocyanate may be a diisocyanate, a triisocyanate, a tetraisocyanate or a polymeric isocyanate. In some examples, the polyisocyanate may be a diisocyanate or a polymeric isocyanate. In some examples, the polyisocyanate may be a diisocyanate.

In some examples, the polyisocyanate may be a diisocyanate selected form from (i) aromatic diisocyanates, such as methylene[bis(phenyl isocyanate)] (MDI) (e.g., 4,4'- methylene[bis(phenyl isocyanate)], 2,4'-methylene[bis(phenyl isocyanate)], or 2,2'- methylene[bis(phenyl isocyanate)]), xylylene diisocyanate (XDI) (e.g., m-xylylene diisocyanate), tetra methyl xylylene diisocyanate (e.g., 1 ,3-bis(1-isocyanato-1-methylethyl)- benzene), phenylene diisocyanate (e.g., 1 ,3-phenylene diisocyanate, or 1 ,4-phenylene diisocyanate), naphthalene diisocyanate (e.g., 1 ,5-naphthalene diisocyanate), dimethyl biphenyl diisocyanate (TODI) (e.g., 3,3'-dimethyl-4,4'-biphenylene diisocyanate), and toluene diisocyanate (TDI) (e.g., 2,4-toluene diisocyanate or 2,6-toluene diisocyanate; (ii) aliphatic diisocyanates, such as isophorone diisocyanate (IPDI), cyclohexyl diisocyanate (CHDI) (e.g., 1 ,4-cyclohexyl diisocyanate), decane diisocyanate (e.g., decane- 1 , 10-diisocyanate), dodecane diisocyanate (e.g., dodecane-1 , 12-diisocyanate) hexa- methylene diisocyanate (HDI), cyclohexyl diisocyanate (e.g., 1 ,4-cyclohexyl diisocyanate), bis(isocyanatomethyl)cyclohexane (CHMDI) (e.g., 1 ,3-bis(isocyanatomethyl)- cyclohexane, or 1 ,4-bis(isocyanatomethyl)cyclohexane)), dicyclohexylmethane diisocyanate (HMDI) (e.g., dicyclohexylmethane-4,4'-diisocyanate), hydrogenated diphenyl- methane diisocyanate, and hydrogenated tolylene diisocyanate.

In some examples, the polyisocyanate may be a polymeric isocyanate. In some examples, the polymeric isocyanate may be polymeric diphenylmethane isocyanate (pMDI) or polymeric hydrogenated diphenylmethane isocyanate. In some examples, the polymeric isocyanate may be polymeric diphenylmethane diisocyanate (pMDI).

In some examples, the polyol, which comprises or consists of a polyether polyol, may be a long-chain polyol, wherein a long-chain polyol has a molecular weight of from at least 500 Daltons. In some examples, the polyol is a polyether polyol. In some examples, the polyether polyol has a molecular weight of at least 500 Daltons. In some examples, the polyether polyol comprises a molecule containing multiple hydroxyl functional groups. In some examples, the polyether polyol comprises a polymeric molecule containing multiple hydroxyl functional groups. In some examples, the polyether polyol comprises at least two hydroxyl functional groups. In some examples, the polyether polyol comprise two hydroxyl functional groups, that is, the polyether polyol is a polyether diol.

In some examples, the polyether polyol comprises a hydroxyl-terminated polyether, that is, a polyether diol in which the hydroxyl groups are terminal groups. In some examples, the polyether polyol comprises a hydroxyl-substituted polyether, that is, a polyether with hydroxyl substituents along the polyether chain.

In some examples, the polyether polyol is a polymer of an alkylene glycol. In some examples, the polyether polyol may comprise a polymer of diethylene glycol, dipropylene glycol, 1 ,4-butane diol, 1 ,6-hexanediol, 1 ,3-butanediol, 1 ,5-pentanediol, 1 ,4-cyclohexanedimethanol, neopentyl glycol, 1 ,9-nonanediol, 1 ,12-dodecanediol and the like. In some examples, the polyether polyol may comprise a polyethylene glycol) diol, poly(oxypropylene) diol or a poly(oxytetramethylene) diol. In some examples, the polyether polyol may be a polyglycerol or a polysaccharide. In some examples, the polysaccharide may be a polysucrose or polysorbitol.

In some examples, the so-called chain extender comprise a diamine, an aminoalcohol, a diol, or a mixture thereof. In some examples, the diol chain extender may be a short chain diol having a molecular weight of 400 Daltons or less. In some examples, the chain extender may comprise a diamine, an aminoalcohol or a mixture thereof.

Suitable chain extenders include aliphatic diamines, cycloaliphatic diamines, aromatic diamines, aliphatic aminoalcohols, cycloaliphatic aminoalcohols, aromatic aminoalcohols, aliphatic diols, cycloaliphatic diols and aromatic diols. In some examples, the chain extender may be aliphatic diamines, cycloaliphatic diamines, aromatic diamines, aliphatic aminoalcohols, cycloaliphatic aminoalcohols or aromatic aminoalcohols, In some examples, the chain extender may be aliphatic diamines or aliphatic aminoalcohols.

In some examples, the chain extender may comprise a diamine, an aminoalcohol and/or a diol. In some examples, the chain extender may comprise a diamine and an aminoalcohol. In some examples, the chain extender may be selected from diamines and aminoalcohols. In some examples, the chain extender may be a diamine. In some examples, the chain extender may be a diamine, an aminoalcohol or a diol and may have from 2 to about 20 carbon atoms. In some examples, the chain extender may be a diamine having 2 to about 20 carbon atoms. In some examples, the chain extender may be an aminoalcohol having 2 to about 20 carbon atoms. In some examples, the chain extender may be a diol having 2 to about 20 carbon atoms.

Suitable chain extenders include glycols and can be aliphatic, aromatic or combinations thereof. In some cases, the chain extenders are glycols having from 2 to about 20 carbon atoms. In some examples, the glycol chain extenders are lower aliphatic or short-chain glycols having from about 4 to about 12 carbon atoms and include, for example, diethylene glycol, dipropylene glycol, 1 ,4-butane diol, 1 ,6-hexanediol, 1 ,3- butanediol, 1 ,5-pentanediol, 1 ,4-cyclohexanedimethanol, neopentyl glycol, 1 ,9- nonanediol, 1 ,12-dodecanediol and the like. In some embodiments, the chain extender is comprised solely of 1 ,6-hexanediol.

In some examples, the chain extender may comprise an aromatic glycol. In some examples, the aromatic glycol may be benzene glycol or xylene glycol. Xylene glycol may be a mixture of 1 ,4-di(hydroxymethyl)benzene and 1 ,2-di(hydroxymethyl)benzene. The benzene glycol may be hydroquinone bis(betahydroxyethyl)ether (HQEE), 1 ,3- di(2-hydroxyethyl)benzene, 1 ,2-di(2-hydroxyethoxy)benzene, or combinations thereof.

In some examples, the chain extender may be selected from aliphatic diamines having 2 to 20 carbon atoms, cycloaliphatic diamines having 3 to 20 carbon atoms, or aromatic diamines having 5 to 20 carbon atoms. In some examples, the chain extender may be selected from aliphatic diamines having 2 to 20 carbon atoms, for example, 2 to 12 carbon atoms. In some examples, the chain extender may be ethanediamine, propanediamine, butanediamine, pentyldiamine, or hexyldiamine.

In some examples, the chain extender may be selected from aliphatic aminoalohols having 2 to 20 carbon atoms, cycloaliphatic aminoalcohols having 3 to 20 carbon atoms or aromatic aminoalcohols having 5 to 20 carbon atoms. In some examples, the chain extender may be selected from aliphatic aminoalcohols having 2 to 20 carbon atoms, for example, 2 to 12 carbon atoms. In some examples, the chain extender may be aminoethanol, aminopropanol, aminobutanol, aminopentanol, aminohexanol. In some examples, the ratio of polyether polyol molecules to chain extender molecules may be from 10:1 to 1 : 1 , for example, from 5:1 to 1 :1 or 1 : 1.

In some examples, the polyether-based thermoplastic polyurethane comprises urethane groups and urea groups. In some examples, urea groups form at least 40% of the total amount of urethane and urea groups in the polyurethane, for example, at least 45% of the total amount of urethane and urea groups in the polyurethane, for example, at least 50% of the total amount of urethane and urea groups. An FTIR spectrum of a polyurethane shows a peak for the C=0 stretching of urea groups at approximately 1700 cm ¹ and a peak for the C=0 stretching of urethane groups at approximately 1730 cm ¹.

In some examples, the surface of the polyether-based thermoplastic polyurethane film comprises urethane groups and urea groups. In some examples, the surface of the polyether-based thermoplastic polyurethane film comprises more urethane groups than urea groups. In some examples, ATR-FTIR spectroscopy of the surface of the polyether-based thermoplastic polyurethane film results in a peak for C=0 stretching of urea groups with an intensity of 0.3 a.u. or more and a peak for C=0 stretching of urethane groups with an intensity of 0.3 a.u. or more. In some examples, ATR-FTIR spectroscopy of the surface of the polyether-based thermoplastic polyurethane film results in a peak for C=0 stretching of urea groups of 0.4 a.u. or more and a peak for C=0 stretching of urethane groups with an intensity of 0.4 a.u. or more. In some examples, ATR-FTIR spectroscopy of the surface of the polyether-based thermoplastic polyurethane film results in a peak for C=0 stretching of urea groups of 0.5 a.u. or more and a peak for C=0 stretching of urethane groups with an intensity of 0.5 a.u. or more. In some examples, ATR-FTIR spectroscopy of the surface of the polyether- based thermoplastic polyurethane film results in a peak for C=0 stretching of urea groups of 0.6 a.u. or more and a peak for C=0 stretching of urethane groups with an intensity of 0.6 a.u. or more. In some examples, ATR-FTIR spectroscopy of the surface of the polyether-based thermoplastic polyurethane film results in the peak for C=0 stretching of urethane groups having a higher intensity than the peak for C=0 stretching of urea groups. Support layer

In some examples, a support layer is disposed on the polyether-based thermoplastic polyurethane film. The support layer is detachable from the polyether-based thermoplastic polyurethane film. In some examples, the support layer provides structural support to the polyether-based thermoplastic polyurethane film. In some examples, the support layer may be any substrate capable of providing structural support to the polyether-based thermoplastic polyurethane film.

In some examples, the support layer may stop the polyether-based thermoplastic polyurethane film adhering to the liquid electrostatic printer during liquid electrostatic printing. In some examples, the support layer may be any substrate capable of stopping the polyether-based thermoplastic polyurethane film adhering to the liquid electrostatic printer.

In some examples, the support layer may provide structural support to the printed film. In some examples, the support layer may protect the polyether-based thermoplastic polyurethane film of the printed film, that is, the heat transferable printed image.

In some examples, the support layer may stop the polyether-based thermoplastic polyurethane film adhering to the heating element during adhesion of the printed film to the target substrate. In some examples, the support layer may be any substrate capable of stopping the polyether-based thermoplastic polyurethane film adhering to the heating element during adhesion of the printed film to the target substrate.

In some examples, the support layer may be paper or a polymeric film. In some examples, the polymeric film may be polyethylene terephthalate. In some examples, the support layer may be paper. In some examples, the support layer may be any type of paper, for example, coated paper, uncoated paper or surface modified paper. In some examples, the support layer may be a silicon release liner or silicon paper. In some examples, the support layer may be kitchen baking paper. In some examples, the support layer may be coated paper, for example, silicon coated paper or Teflon™ coated paper. In some examples, the coated paper comprises a paper material coated with a polymeric material. In some examples, the coated paper comprises a paper material with an inorganic material bound to the surface of the paper by a polymeric material. In some examples, the support layer may be any type of paper that can be peeled from the polyether-based thermoplastic polyurethane film.

Protective layer

In some examples, a protective layer may be contacted with the liquid electrostatically printed ink. The protective layer may or may not be adhered to the liquid electrostatically printed ink. The protective layer is detachable from the liquid electrostatically printed ink.

The protective layer may stop the liquid electrostatically printed ink adhering to the heating element during adhesion of the printed film to the target substrate. In some examples, the protective layer may be any substrate capable of stopping the liquid electrostatically printed ink adhering to the heating element during adhesion of the printed film to the target substrate.

In some examples, the protective layer may be paper or a polymeric film. In some examples, the polymeric film may be polyethylene terephthalate. In some examples, the paper may be coated paper, uncoated paper or surface modified paper. In some examples, the paper may be silicon release liners or silicon paper. In some examples, the paper may be standard kitchen baking paper. In some examples, the protective layer may be coated paper, for example, silicon coated paper or Teflon™ coated paper. In some examples, the coated paper comprises a paper material coated with a polymeric material. In some examples, the coated paper comprises a paper material with an inorganic material bound to the surface of the paper by a polymeric material. In some examples, the support layer may be any type of paper that can be peeled from the liquid electrostatically printed ink.

Liquid electrostatic ink composition

The liquid electrostatic ink composition may comprise a thermoplastic resin. In some examples, the liquid electrostatic ink composition may comprise a thermoplastic resin and a colorant. In some examples, the liquid electrostatic ink composition may further comprise a charge adjuvant and/or a charge director. Liquid Carrier

In some examples, when printing, the liquid electrostatic ink composition comprises a liquid carrier. Generally, the liquid carrier can act as a dispersing medium for the other components in the liquid electrostatic ink composition. For example, the liquid carrier can comprise or be a hydrocarbon, silicone oil, vegetable oil, etc. The liquid carrier can include, but is not limited to, an insulating, non-polar, non-aqueous liquid that can be used as a medium for toner particles. The liquid carrier can include compounds that have a resistivity in excess of about 10⁹ ohm cm. The liquid carrier may have a dielectric constant below about 5, in some examples below about 3. The liquid carrier can include, but is not limited to, hydrocarbons. The hydrocarbon can include, but is not limited to, an aliphatic hydrocarbon, an isomerized aliphatic hydrocarbon, branched chain aliphatic hydrocarbons, aromatic hydrocarbons, and combinations thereof. Examples of the liquid carriers include, but are not limited to, aliphatic hydrocarbons, isoparaffinic compounds, paraffinic compounds, dearomatized hydrocarbon compounds, and the like. In particular, the liquid carriers can include, but are not limited to, Isopar-G™, Isopar-H™, Isopar-L™, Isopar-M™, Isopar-K™, Isopar-V™, Norpar 12™, Norpar 13™, Norpar 15™, Exxol D40™, Exxol D80™, Exxol D100™, Exxol D130™, and Exxol D140™ (each sold by EXXON CORPORATION); Teclen N-16™, Teclen N-20™, Teclen N-22™, Nisseki Naphthesol L™, Nisseki Naphthesol M™, Nisseki Naphthesol H™, #0 Solvent L™, #0 Solvent M™, #0 Solvent H™, Nisseki Isosol 300™, Nisseki Isosol 400™, AF-4™, AF-5™, AF-6™ and AF-7™ (each sold by NIPPON OIL CORPORATION); IP Solvent 1620™ and IP Solvent 2028™ (each sold by IDEMITSU PETROCHEMICAL CO., LTD.); Amsco OMS™ and Amsco 460™ (each sold by AMERICAN MINERAL SPIRITS CORP.); and Electron, Positron, New II, Purogen HF (100% synthetic terpenes) (sold by ECOLINK™).

Before electrostatic printing, the liquid carrier can constitute about 20% to 99.5% by weight of the liquid electrostatic ink composition, in some examples 50% to 99.5% by weight of the liquid electrostatic ink composition. Before printing, the liquid carrier may constitute about 40% to 90% by weight of the liquid electrostatic ink composition. Before printing, the liquid carrier may constitute about 60% to 80% by weight of the liquid electrostatic ink composition. Before printing, the liquid carrier may constitute about 90% to 99.5% by weight of the liquid electrostatic ink composition, in some examples 95% to 99% by weight of the liquid electrostatic ink composition. The liquid electrostatic ink composition, once electrostatically printed on the polyether- based thermoplastic polyurethane film (i.e., the liquid electrostatically printed ink), may be substantially free from liquid carrier. In an electrostatic printing process and/or afterwards, the liquid carrier may be removed, for example, by an electrophoresis processes during printing and/or evaporation, such that substantially just solids are transferred to the polyether-based thermoplastic polyurethane. Substantially free from liquid carrier may indicate that liquid electrostatically printed ink contains less than 5 wt.% liquid carrier, in some examples, less than 2 wt.% liquid carrier, in some examples less than 1 wt.% liquid carrier, in some examples less than 0.5 wt.% liquid carrier. In some examples, liquid electrostatically printed ink is free from liquid carrier.

Thermoplastic Resin

In some examples, the liquid electrostatic ink composition comprises a thermoplastic resin. In some examples, the liquid electrostatic ink composition comprises chargeable particles (i.e. having or capable of developing a charge, for example, in an electromagnetic field) including the thermoplastic resin, in some examples, including the thermoplastic resin and the colorant.

The thermoplastic resin may be any thermoplastic resin that is able to swell in a carrier liquid, for example a non-polar carrier liquid, as described herein. By swelling, it is meant that the resin is capable of increasing in size as a result of accumulation of the carrier liquid, e.g. non-polar carrier liquid. The swellable thermoplastic resin is also able to emit the carrier liquid when phase separation is initiated (e.g., when the swollen resin is exposed to heat at a temperature ranging from about 50°C to about 80°C). Examples of the swellable resin include ethylene acrylic acid copolymers and/or ethylene methacrylic acid copolymers. Both ethylene acrylic acid copolymers and ethylene methacrylic acid copolymers are commercially available under the tradename NUCREL® from E. I. du Pont de Nemours and Company, Wilmington, DE. The swelling of these types of resins may be due, at least in part, to the molecular structure similarity between the ethylene-based resin(s) and the non-polar carrier liquid. It is to be understood that any other homopolymer or copolymer that is capable of swelling in a non-polar carrier liquid and is also capable of releasing the non-polar carrier liquid when exposed to suitable heat conditions may also be used. The thermoplastic resin may comprise a copolymer of an alkylene monomer and a monomer selected from acrylic acid and methacrylic acid. The thermoplastic resin may be referred to as a thermoplastic polymer. In some examples, the polymer may comprise one or more of ethylene or propylene acrylic acid co-polymers; ethylene or propylene methacrylic acid co-polymers; ethylene vinyl acetate co-polymers; co polymers of ethylene or propylene (e.g. 80 wt.% to 99.9 wt.%), and alkyl (e.g. C1 to C5) ester of methacrylic or acrylic acid (e.g. 0.1 wt.% to 20 wt.%); co-polymers of ethylene (e.g. 80 wt.% to 99.8 wt.%), acrylic or methacrylic acid (e.g. 0.1 wt.% to 20 wt.%) and alkyl (e.g. C1 to C5) ester of methacrylic or acrylic acid (e.g. 0.1 wt.% to 20 wt.%); co polymers of ethylene or propylene (e.g. 70 wt.% to 99.9 wt.%) and maleic anhydride (e.g. 0.1 wt.% to 30 wt.%); polyethylene; polystyrene; isotactic polypropylene (crystalline); co-polymers of ethylene ethylene ethyl acrylate; polyesters; polyvinyl toluene; polyamides; styrene/butadiene co-polymers; epoxy resins; acrylic resins (e.g. co-polymer of acrylic or methacrylic acid and at least one alkyl ester of acrylic or methacrylic acid wherein alkyl may have from 1 to about 20 carbon atoms, such as methyl methacrylate (e.g. 50% to 90%)/methacrylic acid (e.g. 0 wt.% to 20 wt.%)/ethylhexylacrylate (e.g. 10 wt.% to 50 wt.%)); ethylene-acrylate terpolymers: ethylene-acrylic esters-maleic anhydride (MAH) or glycidyl methacrylate (GMA) terpolymers; ethylene-acrylic acid ionomers and combinations thereof.

The thermoplastic resin may comprise a polymer having acidic side groups. Examples of the polymer having acidic side groups will now be described. The polymer having acidic side groups may have an acidity of 50 mg KOH/g or more, in some examples an acidity of 60 mg KOH/g or more, in some examples an acidity of 70 mg KOH/g or more, in some examples an acidity of 80 mg KOH/g or more, in some examples an acidity of 90 mg KOH/g or more, in some examples an acidity of 100 mg KOH/g or more, in some examples an acidity of 105 mg KOH/g or more, in some examples 1 10 mg KOH/g or more, in some examples 1 15 mg KOH/g or more. The polymer having acidic side groups may have an acidity of 200 mg KOH/g or less, in some examples 190 mg or less, in some examples 180 mg or less, in some examples 130 mg KOH/g or less, in some examples 120 mg KOH/g or less. Acidity of a polymer, as measured in mg KOH/g can be measured using standard procedures known in the art, for example using the procedure described in ASTM D1386. The thermoplastic resin may comprise a polymer having acidic side groups, that has a melt flow rate of less than about 70 g/10 minutes, in some examples about 60 g/10 minutes or less, in some examples about 50 g/10 minutes or less, in some examples about 40 g/10 minutes or less, in some examples 30 g/10 minutes or less, in some examples 20 g/10 minutes or less, in some examples 10 g/10 minutes or less. In some examples, all polymers having acidic side groups and/or ester groups in the particles each individually have a melt flow rate of less than 90 g/10 minutes, 80 g/10 minutes or less, in some examples 70 g/10 minutes or less, in some examples 70 g/10 minutes or less, in some examples 60 g/10 minutes or less.

The polymer having acidic side groups can have a melt flow rate of about 10 g/10 minutes to about 120 g/10 minutes, in some examples about 10 g/10 minutes to about 70 g/10 minutes, in some examples about 10 g/10 minutes to 40 g/10 minutes, in some examples 20 g/10 minutes to 30 g/10 minutes. The polymer having acidic side groups can have a melt flow rate of, in some examples, about 50 g/10 minutes to about 120 g/10 minutes, in some examples 60 g/10 minutes to about 100 g/10 minutes. The melt flow rate can be measured using standard procedures known in the art, for example as described in ASTM D1238.

The acidic side groups may be in free acid form or may be in the form of an anion and associated with one or more counterions, typically metal counterions, e.g. a metal selected from the alkali metals, such as lithium, sodium and potassium, alkali earth metals, such as magnesium or calcium, and transition metals, such as zinc. The polymer having acidic side groups can be selected from resins such as co-polymers of ethylene and an ethylenically unsaturated acid of either acrylic acid or methacrylic acid; and ionomers thereof, such as methacrylic acid and ethylene-acrylic or methacrylic acid co-polymers which are at least partially neutralized with metal ions (e.g. Zn, Na, Li) such as SURLYN® ionomers. The polymer comprising acidic side groups can be a copolymer of ethylene and an ethylenically unsaturated acid of either acrylic or methacrylic acid, where the ethylenically unsaturated acid of either acrylic or methacrylic acid constitutes from 5 wt.% to about 25 wt.% of the co-polymer, in some examples from 10 wt.% to about 20 wt.% of the co-polymer.

The thermoplastic resin may comprise two different polymers having acidic side groups. The two polymers having acidic side groups may have different acidities, which may fall within the ranges mentioned above. The resin may comprise a first polymer having acidic side groups that has an acidity of from 10 mg KOH/g to 1 10 mg KOH/g, in some examples 20 mg KOH/g to 1 10 mg KOH/g, in some examples 30 mg KOH/g to 1 10 mg KOH/g, in some examples 50 mg KOH/g to 1 10 mg KOH/g, and a second polymer having acidic side groups that has an acidity of 1 10 mg KOH/g to 130 mg KOH/g.

The thermoplastic resin may comprise two different polymers having acidic side groups: a first polymer having acidic side groups that has a melt flow rate of about 10 g/10 minutes to about 50 g/10 minutes and an acidity of from 10 mg KOH/g to 1 10 mg KOH/g, in some examples 20 mg KOH/g to 110 mg KOH/g, in some examples 30 mg KOH/g to 1 10 mg KOH/g, in some examples 50 mg KOH/g to 1 10 mg KOH/g, and a second polymer having acidic side groups that has a melt flow rate of about 50 g/10 minutes to about 120 g/10 minutes and an acidity of 1 10 mg KOH/g to 130 mg KOH/g. The first and second polymers may be absent of ester groups.

The ratio of the first polymer having acidic side groups to the second polymer having acidic side groups can be from about 10:1 to about 2:1. The ratio can be from about 6:1 to about 3:1 , in some examples about 4:1.

The thermoplastic resin may comprise a polymer having a melt viscosity of 15000 poise or less, in some examples a melt viscosity of 10000 poise or less, in some examples 1000 poise or less, in some examples 100 poise or less, in some examples 50 poise or less, in some examples 10 poise or less; said polymer may be a polymer having acidic side groups as described herein. The thermoplastic resin may comprise a first polymer having a melt viscosity of 15000 poise or more, in some examples 20000 poise or more, in some examples 50000 poise or more, in some examples 70000 poise or more; and in some examples, the thermoplastic resin may comprise a second polymer having a melt viscosity less than the first polymer, in some examples a melt viscosity of 15000 poise or less, in some examples a melt viscosity of 10000 poise or less, in some examples 1000 poise or less, in some examples 100 poise or less, in some examples 50 poise or less, in some examples 10 poise or less. The thermoplastic resin may comprise a first polymer having a melt viscosity of more than 60000 poise, in some examples from 60000 poise to 100000 poise, in some examples from 65000 poise to 85000 poise; a second polymer having a melt viscosity of from 15000 poise to 40000 poise, in some examples 20000 poise to 30000 poise, and a third polymer having a melt viscosity of 15000 poise or less, in some examples a melt viscosity of 10000 poise or less, in some examples 1000 poise or less, in some examples 100 poise or less, in some examples 50 poise or less, in some examples 10 poise or less; an example of the first polymer is Nucrel® 960 (from DuPont), an example of the second polymer is Nucrel® 699 (from DuPont), and an example of the third polymer is AC®-5120 or AC®-5180 (from Honeywell). The first, second and third polymers may be polymers having acidic side groups as described herein. The melt viscosity can be measured using a rheometer, e.g. a commercially available AR-2000 Rheometer from Thermal Analysis Instruments, using the geometry of: 25mm steel plate-standard steel parallel plate, and finding the plate over plate rheometry isotherm at 120°C, 0.01 Hz shear rate.

If the thermoplastic resin comprises a single type of polymer, the polymer (excluding any other components of the electrophotographic adhesive composition) may have a melt viscosity of 6000 poise or more, in some examples a melt viscosity of 8000 poise or more, in some examples a melt viscosity of 10000 poise or more, in some examples a melt viscosity of 12000 poise or more. If the thermoplastic resin comprises a plurality of polymers all the polymers of the resin may together form a mixture (excluding any other components of the electrophotographic adhesive composition) that has a melt viscosity of 6000 poise or more, in some examples a melt viscosity of 8000 poise or more, in some examples a melt viscosity of 10000 poise or more, in some examples a melt viscosity of 12000 poise or more. Melt viscosity can be measured using standard techniques. The melt viscosity can be measured using a rheometer, e.g. a commercially available AR-2000 Rheometer from Thermal Analysis Instruments, using the geometry of: 25mm steel plate-standard steel parallel plate, and finding the plate over plate rheometry isotherm at 120°C, 0.01 Hz shear rate.

The thermoplastic resin may comprise two different polymers having acidic side groups that are selected from co-polymers of ethylene and an ethylenically unsaturated acid of either acrylic acid or methacrylic acid; or ionomers thereof, such as methacrylic acid and ethylene-acrylic or methacrylic acid co-polymers which are at least partially neutralized with metal ions (e.g. Zn, Na, Li) such as SURLYN® ionomers. The resin may comprise (i) a first polymer that is a co-polymer of ethylene and an ethylenically unsaturated acid of either acrylic acid and methacrylic acid, wherein the ethylenically unsaturated acid of either acrylic or methacrylic acid constitutes from 8 wt.% to about 16 wt.% of the co-polymer, in some examples 10 wt.% to 16 wt.% of the co-polymer; and (ii) a second polymer that is a co-polymer of ethylene and an ethylenically unsaturated acid of either acrylic acid and methacrylic acid, wherein the ethylenically unsaturated acid of either acrylic or methacrylic acid constitutes from 12 wt.% to about 30 wt.% of the co-polymer, in some examples from 14 wt.% to about 20 wt.% of the co polymer, in some examples from 16 wt.% to about 20 wt.% of the co-polymer in some examples from 17 wt.% to 19 wt.% of the co-polymer.

The thermoplastic resin may comprise a polymer having acidic side groups, as described above (which may be free of ester side groups), and a polymer having ester side groups. The polymer having ester side groups may be a thermoplastic polymer. The polymer having ester side groups may further comprise acidic side groups. The polymer having ester side groups may be a co-polymer of a monomer having ester side groups and a monomer having acidic side groups. The polymer may be a co-polymer of a monomer having ester side groups, a monomer having acidic side groups, and a monomer absent of any acidic and ester side groups. The monomer having ester side groups may be a monomer selected from esterified acrylic acid or esterified methacrylic acid. The monomer having acidic side groups may be a monomer selected from acrylic or methacrylic acid. The monomer absent of any acidic and ester side groups may be an alkylene monomer, including, but not limited to, ethylene or propylene. The esterified acrylic acid or esterified methacrylic acid may, respectively, be an alkyl ester of acrylic acid or an alkyl ester of methacrylic acid. The alkyl group in the alkyl ester of acrylic or methacrylic acid may be an alkyl group having 1 to 30 carbons, in some examples 1 to 20 carbons, in some examples 1 to 10 carbons; in some examples selected from methyl, ethyl, iso-propyl, n-propyl, t-butyl, iso-butyl, n-butyl and pentyl.

The polymer having ester side groups may be a co-polymer of a first monomer having ester side groups, a second monomer having acidic side groups and a third monomer which is an alkylene monomer absent of any acidic and ester side groups. The polymer having ester side groups may be a co-polymer of (i) a first monomer having ester side groups selected from esterified acrylic acid or esterified methacrylic acid, in some examples an alkyl ester of acrylic or methacrylic acid, (ii) a second monomer having acidic side groups selected from acrylic or methacrylic acid and (iii) a third monomer which is an alkylene monomer selected from ethylene and propylene. The first monomer may constitute 1 % to 50% by weight of the co-polymer, in some examples 5% to 40% by weight, in some examples 5% to 20% by weight of the co-polymer, in some examples 5% to 15% by weight of the co-polymer. The second monomer may constitute 1% to 50% by weight of the co-polymer, in some examples 5% to 40% by weight of the co-polymer, in some examples 5% to 20% by weight of the co-polymer, in some examples 5% to 15% by weight of the co-polymer. In some examples, the first monomer can constitute 5% to 40% by weight of the co-polymer and the second monomer can constitute 5% to 40% by weight of the co-polymer, with the third monomer constituting the remaining weight of the co-polymer. In some examples, the first monomer constitutes 5% to 15% by weight of the co-polymer and the second monomer constitutes 5% to 15% by weight of the co-polymer, with the third monomer constituting the remaining weight of the co-polymer. In some examples, the first monomer constitutes 8% to 12% by weight of the co-polymer and the second monomer constitutes 8% to 12% by weight of the co-polymer, with the third monomer constituting the remaining weight of the co-polymer. In some examples, the first monomer constitutes about 10% by weight of the co-polymer and the second monomer constitutes about 10% by weight of the co-polymer, and with the third monomer constituting the remaining weight of the co-polymer. The polymer may be selected from the Bynel® class of monomer, including Bynel® 2022 and Bynel® 2002, which are available from DuPont®.

The polymer having ester side groups may constitute 1 % or more by weight of the total amount of the thermoplastic resin, e.g. thermoplastic resin polymers, in the liquid electrostatic ink composition and/or the liquid electrostatically printed ink on the polyether-based thermoplastic polyurethane film or the target substrate, e.g. the total amount of the polymer or polymers having acidic side groups and polymer having ester side groups. The polymer having ester side groups may constitute 5% or more by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in some examples 8% or more by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in some examples 10% or more by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in some examples 15% or more by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in some examples 20% or more by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in some examples 25% or more by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in some examples 30% or more by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in some examples 35% or more by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in the liquid electrostatic ink composition and/or the liquid electrostatically printed ink on the polyether-based thermoplastic polyurethane film or the target substrate. The polymer having ester side groups may constitute from 5% to 50% by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in the liquid electrostatic ink composition and/or the liquid electrostatically printed ink on the polyether-based thermoplastic polyurethane film or the target substrate, in some examples 10% to 40% by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in the liquid electrostatic ink composition and/or the liquid electrostatically printed ink on the polyether-based thermoplastic polyurethane film or the target substrate, in some examples 5% to 30% by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in the liquid electrostatic ink composition and/or the liquid electrostatically printed ink on the polyether-based thermoplastic polyurethane film or the target substrate, in some examples 5% to 15% by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in the liquid electrostatic ink composition and/or the liquid electrostatically printed ink on the polyether-based thermoplastic polyurethane film or the target substrate, in some examples 15% to 30% by weight of the total amount of the resin polymers, e.g. thermoplastic resin polymers, in liquid electrostatic ink composition and/or the liquid electrostatically printed ink on the polyether-based thermoplastic polyurethane film or the target substrate.

The polymer having ester side groups may have an acidity of 50 mg KOH/g or more, in some examples an acidity of 60 mg KOH/g or more, in some examples an acidity of 70 mg KOH/g or more, in some examples an acidity of 80 mg KOH/g or more. The polymer having ester side groups may have an acidity of 100 mg KOH/g or less, in some examples 90 mg KOH/g or less. The polymer having ester side groups may have an acidity of 60 mg KOH/g to 90 mg KOH/g, in some examples 70 mg KOH/g to 80 mg KOH/g.

The polymer having ester side groups may have a melt flow rate of about 10 g/10 minutes to about 120 g/10 minutes, in some examples about 10 g/10 minutes to about 50 g/10 minutes, in some examples about 20 g/10 minutes to about 40 g/10 minutes, in some examples about 25 g/10 minutes to about 35 g/10 minutes. The polymer, polymers, co-polymer or co-polymers of the resin can in some examples be selected from the Nucrel® family of toners (e.g. Nucrel 403™, Nucrel 407™, Nucrel 609HS™, Nucrel 908HS™, Nucrel 1202HC™, Nucrel 30707™, Nucrel 1214™, Nucrel 903™, Nucrel 3990™, Nucrel 910™, Nucrel 925™, Nucrel 699™, Nucrel 599™, Nucrel 960™, Nucrel RX 76™, Nucrel 2806™, Bynell 2002™, Bynell 2014™, Bynell 2020™ and Bynell 2022™, (sold by E. I. du PONT™)), the AC® family of toners (e.g. AC- 5120™, AC-5180™, AC-540™, AC-580™ (sold by Honeywell™)), the Aclyn™ family of toners (e.g. Aclyn 201™, Aclyn 246™, Aclyn 285™, and Aclyn 295™), and the Lotader™ family of toners (e.g. Lotader 2210™, Lotader, 3430™, and Lotader 8200™ (sold by Arkema™)).

The thermoplastic resin of the liquid electrostatic ink composition or the liquid electrostatically printed ink may be softened to allow transfer of the printed film to a target substrate.

In some examples, the thermoplastic resin may have a softening point (e.g. as measured by dynamic mechanical analysis according to ASTM E1953 at a temperature ramp of 3°C/min and a constant frequency of 1 Hz, a Vicat softening point as measured according to ASTM D1525 or the Ring and Ball softening point as determined according to ASTM E28-99) of about 30°C or greater, for example about 40°C or greater, about 50°C or greater, or about 60°C or greater.

In some examples, the thermoplastic resin may have a softening point (e.g. as measured by dynamic mechanical analysis according to ASTM E1953 at a temperature ramp of 3°C/min and a constant frequency of 1 Hz, a Vicat softening point as measured according to ASTM D1525 or the Ring and Ball softening point as determined according to ASTM E28-99) of up to about 150°C, for example up to about 130°C, up to about 120°C, up to about 1 10°C, or up to about 100°C.

In some examples, the thermoplastic resin may have a softening point (e.g. as measured by dynamic mechanical analysis according to ASTM E1953 at a temperature ramp of 3°C/min and a constant frequency of 1 Hz, a Vicat softening point as measured according to ASTM D1525 or the Ring and Ball softening point as determined according to ASTM E28-99) in the range of about 60°C to about 150°C, for example about 60°C to about 1 10°C.

Charge Director and Charge Adjuvant

In some examples, the liquid electrostatic ink composition further comprises either a charge director or a charge adjuvant or both.

In some examples, the liquid electrostatic ink composition includes a charge director. The charge director may be added to a liquid electrostatic ink composition in order to impart and/or maintain sufficient electrostatic charge on the particles of the composition. In some examples, the charge director may comprise ionic compounds, particularly metal salts of fatty acids, metal salts of sulfo-succinates, metal salts of oxyphosphates, metal salts of alkyl-benzenesulfonic acid, metal salts of aromatic carboxylic acids or sulfonic acids, as well as zwitterionic and non-ionic compounds, such as polyoxyethylated alkylamines, lecithin, polyvinylpyrrolidone, organic acid esters of polyvalent alcohols, etc. The charge director can be selected from, but is not limited to, oil-soluble petroleum sulfonates (e.g. neutral Calcium Petronate™, neutral Barium Petronate™, and basic Barium Petronate™), polybutylene succinimides (e.g. OLOA™ 1200 and Amoco 575), and glyceride salts (e.g. sodium salts of phosphated mono- and diglycerides with unsaturated and saturated acid substituents), sulfonic acid salts including, but not limited to, barium, sodium, calcium, and aluminum salts of sulfonic acid. The sulfonic acids may include, but are not limited to, alkyl sulfonic acids, aryl sulfonic acids, and sulfonic acids of alkyl succinates. The charge director can impart a negative charge or a positive charge on the resin-containing particles of a liquid electrostatic ink composition.

The charge director may be added in order to impart and/or maintain sufficient electrostatic charge on particles of the liquid electrostatic ink composition, which may be particles comprising the thermoplastic resin and/or the thermoplastic resin and a colorant.

In some examples, the liquid electrostatic ink composition comprises a charge director comprising a simple salt. The ions constructing the simple salts are all hydrophilic. The simple salt may include a cation selected from the group consisting of Mg, Ca, Ba, NH₄, tert-butyl ammonium, Li⁺, and Al³⁺, or from any sub-group thereof. The simple salt may include an anion selected from the group consisting of S0₄ ² , PO³ , NO³ , HP0₄ ² , C0₃ ² , acetate, trifluoroacetate (TFA), Cl , BF₄ , F , CI0₄ , and Ti0₃ ⁴ or from any sub-group thereof. The simple salt may be selected from CaC0₃, Ba₂Ti0₃, AI₂(S0₄), AI(N0₃)₃, Ca₃(P0₄)₂, BaS0₄, BaHP0₄, Ba₂(P0₄)₃, CaS0₄, (NH₄)₂C0₃, (NH₄)₂S0₄, NH₄OAc, tert- butyl ammonium bromide, NH₄N0₃, LiTFA, AI₂(S0₄)₃, LiCI0₄ and LiBF₄, or any subgroup thereof.

In some examples, the liquid electrostatic ink composition comprises a charge director comprising a sulfosuccinate salt of the general formula MA_n, wherein M is a metal, n is the valence of M, and A is an ion of the general formula (I): [R¹-0-C(0)CH₂CH(S0₃ )- C(0)-0-R²], wherein each of R¹ and R² is an alkyl group. In some examples each of R¹ and R² is an aliphatic alkyl group. In some examples, each of R¹ and R² independently is a C6-25 alkyl. In some examples, said aliphatic alkyl group is linear. In some examples, said aliphatic alkyl group is branched. In some examples, said aliphatic alkyl group includes a linear chain of more than 6 carbon atoms. In some examples, R¹ and R² are the same. In some examples, at least one of R¹ and R² is C₁₃H₂₇. In some examples, M is Na, K, Cs, Ca, or Ba.

In some examples, the charge director comprises at least one micelle forming salt and nanoparticles of a simple salt as described above. The simple salts are salts that do not form micelles by themselves, although they may form a core for micelles with a micelle forming salt. The sulfosuccinate salt of the general formula MA_n is an example of a micelle forming salt. The charge director may be substantially free of an acid of the general formula HA, where A is as described above. The charge director may include micelles of said sulfosuccinate salt enclosing at least some of the nanoparticles of the simple salt. The charge director may include at least some nanoparticles of the simple salt having a size of 200 nm or less, and/or in some examples 2 nm or more.

In some examples, the charge director constitutes about 0.001 % to 20%, in some examples 0.01 % to 20% by weight, in some examples 0.01 to 10% by weight, in some examples 0.01 % to 1 % by weight of the solids of a liquid electrostatic ink composition. In some examples, the charge director constitutes about 0.01 % to 0.5% by weight of the solids of the liquid electrostatic ink composition, in some examples 0.05% to 0.5% by weight of the solids of a liquid electrostatic ink composition, in some examples 0.1 % to 2% by weight of the solids of the liquid electrostatic ink composition, in some examples 0.2% to 1.5% by weight of the solids of the liquid electrostatic ink composition, in some examples 0.1 % to 1 % by weight of the solids of the liquid electrostatic ink composition, in some examples 0.1 % to 0.3% by weight of the solids of the liquid electrostatic ink composition.

In some examples, the charge director is present in an amount of from 3 mg/g to 20 mg/g, in some examples from 3 mg/g to 15 mg/g, in some examples from 10 mg/g to 15 mg/g, in some examples from 5 mg/g to 10 mg/g (where mg/g indicates mg per gram of solids of the liquid electrostatic ink composition).

A charge adjuvant may promote charging of the particles when a charge director is present in the liquid electrostatic ink composition during printing. The charge adjuvant can include, but is not limited to, barium petronate, calcium petronate, Co salts of naphthenic acid, Ca salts of naphthenic acid, Cu salts of naphthenic acid, Mn salts of naphthenic acid, Ni salts of naphthenic acid, Zn salts of naphthenic acid, Fe salts of naphthenic acid, Ba salts of stearic acid, Co salts of stearic acid, Pb salts of stearic acid, Zn salts of stearic acid, Al salts of stearic acid, Zn salts of stearic acid, Cu salts of stearic acid, Pb salts of stearic acid, Fe salts of stearic acid, metal carboxylates (e.g., Al tristearate, Al octanoate, Li heptanoate, Fe stearate, Fe distearate, Ba stearate, Cr stearate, Mg octanoate, Ca stearate, Fe naphthenate, Zn naphthenate, Mn heptanoate, Zn heptanoate, Ba octanoate, Al octanoate, Co octanoate, Mn octanoate, and Zn octanoate), Co lineolates, Mn lineolates, Pb lineolates, Zn lineolates, Ca oleates, Co oleates, Zn palmirate, Ca resinates, Co resinates, Mn resinates, Pb resinates, Zn resinates, AB diblock copolymers of 2-ethylhexyl methacrylate-co-methacrylic acid calcium and ammonium salts, copolymers of an alkyl acrylamidoglycolate alkyl ether (e.g., methyl acrylamidoglycolate methyl ether-co-vinyl acetate), and hydroxy bis(3,5- di-tert-butyl salicylic) aluminate monohydrate. In an example, the charge adjuvant is or includes aluminum di- or tristearate. The charge adjuvant may be present in an amount of about 0.1 % to 5% by weight, in some examples about 0.1 % to 1 % by weight, in some examples about 0.3% to 0.8% by weight of the solids of the liquid electrostatic ink composition, in some examples about 1 wt.% to 3 wt.% of the solids of the liquid electrostatic ink composition, in some examples about 1.5 wt.% to 2.5 wt.% of the solids of the liquid electrostatic ink composition. In some examples, the liquid electrostatic ink composition further includes, e.g. as a charge adjuvant, a salt of multivalent cation and a fatty acid anion. The salt of multivalent cation and a fatty acid anion can act as a charge adjuvant. The multivalent cation may, in some examples, be a divalent or a trivalent cation. In some examples, the multivalent cation is selected from Group 2, transition metals and Group 3 and Group 4 in the Periodic Table. In some examples, the multivalent cation includes a metal selected from Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al and Pb. In some examples, the multivalent cation is Al³⁺. The fatty acid anion may be selected from a saturated or unsaturated fatty acid anion. The fatty acid anion may be selected from a C₈ to C₂₆ fatty acid anion, in some examples a C₁₄ to C₂₂ fatty acid anion, in some examples a C₁₆ to C₂₀ fatty acid anion, in some examples a C₁₇, C₁₈ or C₁₉ fatty acid anion. In some examples, the fatty acid anion is selected from a caprylic acid anion, capric acid anion, lauric acid anion, myristic acid anion, palmitic acid anion, stearic acid anion, arachidic acid anion, behenic acid anion and cerotic acid anion.

The charge adjuvant, which may, for example, be or include a salt of multivalent cation and a fatty acid anion, may be present in an amount of 0.1 wt.% to 5 wt.% of the solids of the liquid electrostatic ink composition, in some examples in an amount of 0.1 wt.% to 2 wt.% of the solids of the liquid electrostatic ink composition, in some examples in an amount of 0.1 wt.% to 2 wt.% of the solids of the liquid electrostatic ink composition, in some examples in an amount of 0.3 wt.% to 1.5 wt.% of the solids of the liquid electrostatic ink composition, in some examples about 0.5 wt.% to 1.2 wt.% of the solids of the liquid electrostatic ink composition, in some examples about 0.8 wt.% to 1 wt.% of the solids of the liquid electrostatic ink composition, in some examples about 1 wt.% to 3 wt.% of the solids of the liquid electrostatic ink composition, in some examples about 1.5 wt.% to 2.5 wt.% of the solids of the liquid electrostatic ink composition.

Colorant

A liquid electrostatic ink composition may further comprise a colorant. A liquid electrostatically printed ink may further comprise a colorant. The colorant may be a dye or a pigment. The colorant can be any colorant compatible with the liquid carrier and useful for electrostatic printing. For example, the colorant may be present as pigment particles or may comprise a resin (in addition to the resins described herein) and a pigment. The resins and pigments can be any of those standardly used. In some examples, the colorant is selected from a cyan pigment, a magenta pigment, a yellow pigment and a black pigment. For example, pigments by Hoechst including Permanent Yellow DHG, Permanent Yellow GR, Permanent Yellow G, Permanent Yellow NCG-71 , Permanent Yellow GG, Hansa Yellow RA, Hansa Brilliant Yellow 5GX-02, Hansa Yellow X, NOVAPERM® YELLOW HR, NOVAPERM® YELLOW FGL, Hansa Brilliant Yellow 10GX, Permanent Yellow G3R-01 , HOSTAPERM® YELLOW H4G, HOSTAPERM® YELLOW H3G, HOSTAPERM® ORANGE GR, HOSTAPERM® SCARLET GO, Permanent Rubine F6B; pigments by Sun Chemical including L74-1357 Yellow, L75-1331 Yellow, L75-2337 Yellow; pigments by Heubach including DALAMAR® YELLOW YT-858-D; pigments by Ciba-Geigy including CROMOPHTHAL® YELLOW 3 G, CROMOPHTHAL® YELLOW GR, CROMOPHTHAL® YELLOW 8 G, IRGAZINE® YELLOW 5GT, IRGALITE® RUBINE 4BL, MONASTRAL® MAGENTA, MONASTRAL® SCARLET, MONASTRAL® VIOLET, MONASTRAL® RED, MONASTRAL® VIOLET; pigments by BASF including LUMOGEN® LIGHT YELLOW, PALIOGEN® ORANGE, HELIOGEN® BLUE L 690 IF, HELIOGEN® BLUE TBD 7010, HELIOGEN® BLUE K 7090, HELIOGEN® BLUE L 710 IF, HELIOGEN® BLUE L 6470, HELIOGEN® GREEN K 8683, HELIOGEN® GREEN L 9140; pigments by Mobay including QUINDO® MAGENTA, INDOFAST® BRILLIANT SCARLET, QUINDO® RED 6700, QUINDO® RED 6713, INDOFAST® VIOLET; pigments by Cabot including Maroon B STERLING® NS BLACK, STERLING® NSX 76, MOGUL® L; pigments by DuPont including TIPURE® R-101 ; and pigments by Paul Uhlich including UHLICH® BK 8200. In some examples, the pigment may be a white pigment. Where the pigment is a white pigment particle, the pigment particle may be selected from the group consisting of Ti0₂, calcium carbonate, zinc oxide, and mixtures thereof. In some examples, the white pigment particle may comprise an alumina-Ti0₂ pigment.

In some examples, the colorant or pigment particles may have a median particle size or d₅₀ of 20 pm or less, for example, 15 pm or less, for example, 10 pm or less, for example, 5 pm or less, for example, 4 pm or less, for example, 3 pm or less, for example, 2 pm or less, for example, 1 pm or less, for example, 0.9 pm or less, for example, 0.8 pm or less, for example, 0.7 pm or less, for example, 0.6 pm or less, for example, 0.5 pm or less. Unless otherwise stated, the particle size of the colorant or pigment particle and the resin coated pigment particle is determined by using laser diffraction on a Malvern Mastersizer 2000 according to the standard procedure as described in the operating manual.

The colorant or pigment particle may be present in a liquid electrostatic ink composition in an amount of from 10 wt.% to 80 wt.% of the total amount of resin and pigment, in some examples, 15 wt.% to 80 wt.%, in some examples, 15 wt.% to 60 wt.%, in some examples, 15 wt.% to 50 wt.%, in some examples, 15 wt.% to 40 wt.%, in some examples, 15 wt.% to 30 wt.% of the total amount of resin and colorant. In some examples, the colorant or pigment particle may be present in a liquid electrostatic ink composition in an amount of at least 50 wt.% of the total amount of resin and colorant or pigment, for example, at least 55 wt.% of the total amount of resin and colorant or pigment.

Other Additives

The liquid electrostatic ink composition may include an additive or a plurality of additives. The additive or plurality of additives may be added at any stage of the method. The additive or plurality of additives may be selected from a wax, a surfactant, biocides, organic solvents, viscosity modifiers, materials for pH adjustment, sequestering agents, preservatives, compatibility additives, emulsifiers and the like. The wax may be an incompatible wax. As used herein, "incompatible wax" may refer to a wax that is incompatible with the resin. Specifically, the wax phase separates from the resin phase upon the cooling of the resin fused mixture on a print substrate during and after the transfer of the liquid electrostatic ink composition to the polyether-based thermoplastic polyurethane, e.g. from an intermediate transfer member, which may be a heated blanket.

Target Substrate

The target substrate may be any suitable medium. The target substrate may be any suitable medium capable of having an image printed thereon. The target substrate may be any suitable medium capable of having an image printed thereon by heat transfer printing. The target substrate may include a material selected from an organic or inorganic material. The material may include a natural polymeric material, e.g. cellulose. The material may include a synthetic polymeric material, e.g. a polymer formed from alkylene monomers, including, but not limited to, polyethylene and polypropylene, and co-polymers such as styrene-polybutadiene. The polypropylene may, in some examples, be biaxially orientated polypropylene. The material may include a metal, which may be in sheet form. The metal may be selected from or made from, for instance, aluminium (Al), silver (Ag), tin (Sn), copper (Cu), mixtures thereof. The metal may be an elemental metal or a metal in alloy form. The material may comprise wood or glass and may be in sheet form. In an example, the target substrate includes a cellulosic paper. In an example, the cellulosic paper is coated with a polymeric material, e.g. a polymer formed from styrene-butadiene resin. In some examples, the cellulosic paper has an inorganic material bound to its surface (before printing with ink) with a polymeric material, wherein the inorganic material may be selected from, for example, kaolinite or calcium carbonate. The target substrate is, in some examples, a cellulosic print medium such as paper. The cellulosic print medium is, in some examples, a coated cellulosic print medium.

In some examples, the target substrate comprises a film or sheet of at least one of paper, metallic foil, and plastic. In some examples, the target substrate is transparent. In some examples, the target substrate comprises a metallized paper or a metallized plastic film. In some examples, the target substrate comprises an aluminium foil. In some examples the target substrate comprises a film of a plastic material, for example, polyethylene (PE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), polypropylene (PP), biaxially oriented polypropylene (BOPP). In some examples, the target substrate comprises a metallized paper in the form of a paper substrate coated on one surface with a layer of metal, for example aluminium. In some examples, the target substrate comprises a metallized plastic film in the form of a polymer substrate coated on one surface with a layer of metal, for example aluminium. In some examples, the target substrate comprises a metallized plastic film in the form of a metallized BOPP film, a metallized PET film, or a metallized polyethylene (PE) film.

In some examples, the target substrate comprises any suitable textile or fabric substrate. In some examples, the textile or fabric substrate may be a network of natural or synthetic fibres. The textile or fabric substrate may be woven or non-woven. The textile or fabric substrate may be formed of yarns, for example, spun threads or filaments, which may be natural or synthetic material or a combination thereof. The textile or fabric substrate may include substrates that have fibres that may be natural and/or synthetic. The target substrate may comprise any textile, fabric material, fabric clothing, or other fabric product onto which it is desired to apply printed matter.

The term“textile” includes, by way of example, cloth, fabric material, fabric clothing or other fabric products. The textile substrate may have warp and weft yarns. The terms “warp” and“weft” refer to weaving terms that have their ordinary meaning in the textile arts, that is, warp refers to lengthwise or longitudinal yarns on a loom whereas weft refers to crosswise or transverse yarns on a loom. The textile substrate may be woven, non-woven, knitted, tufted, crocheted, knotted, and/or have a pressed structure.

It is notable that the term “textile” or“fabric” substrate does not include materials commonly known as any kind of paper. Paper takes the form of sheets, rolls and other physical forms which are made of various plant fibres (like trees) or a mixture of plant fibres with synthetic fibres laid down on a fine screen from a suspension in water.

Furthermore, textile substrates include both textiles in filament form, in the form of fabric material, or even in the form of fabric that has been crafted into a finished article (such as clothing, blankets, tablecloths, napkins, bedding material, curtains, carpet, shoes). In some examples, the textile substrate has a woven, knitted, non-woven or tufted structure.

The textile substrate may be a woven fabric in which warp yarns and weft yarns are mutually positioned at an angle of about 90°. The woven fabric may include, but is not limited to, fabric with a plain weave structure, fabric with a twill weave structure in which the twill weave structure produces diagonal lines on a face of the fabric, or a satin weave. The textile substrate may be a knitted fabric with a loop structure including one or both of a warp-knit fabric and a weft-knit fabric. A weft-knit fabric refers to a knitted fabric in which the loops in the fabric structure that are formed from a separate yarn are mainly introduced in a longitudinal fabric direction. A warp-knit fabric refers to a knitted fabric in which the loops in the fabric structure that are formed from a separate yarn are mainly introduced in a transverse fabric direction. The textile substrate may also be a non-woven product, for example, a flexible fabric that includes a plurality of fibres or filaments that are one or both of bonded together and interlocked together by a chemical treatment process (e.g., a solvent treatment), a mechanical treatment process (e.g., embossing), a thermal treatment process, or a combination of two or more of these processes.

The textile substrate may include one or both of natural fibres and synthetic fibres. Natural fibres that may be used include, but are not limited to, wool, cotton, silk, linen, jute, flax or hemp. Additional fibres that may be used include, but are not limited to, rayon fibres, or thermoplastic aliphatic polymeric fibres derived from renewable resources, including but not limited to, corn starch, tapioca products, or sugarcanes. These additional fibres may be referred to as“natural” fibres. In some examples, the fibres used in the textile substrate include a combination of two or more from the above-listed natural fibres, a combination of any of the above-listed natural fibres with another natural fibre or with a synthetic fibre, or a mixture of two or more from the above-listed natural fibres, or a mixture of any thereof with another natural fibre or with a synthetic fibre.

Synthetic fibres that may be used include polymeric fibres including, but not limited to, polyvinyl chloride (PVC) fibres, polyester (such as polyethylene terephthalate, or polybutylene terephthalate), polyamide, polyimide, polyacrylic, polypropylene, polyethylene, polyurethane, polystyrene, polyaramid (e.g., Kevlar®), polytetrafluoro- ethylene (e.g., Teflon®) (both trade marks of E. I. du Pont de Nemours and Company), fibreglass, polytrimethylene and polycarbonate. In some examples, the fibre used in the textile substrate includes a combination of two or more of the fibres, a combination of any of the fibres with another polymeric fibre or with a natural fibre, a mixture of two or more of the fibres, or a mixture of any of the fibres with another polymer fibre or with a natural fibre. In some examples, the synthetic fibre includes modified fibres. The term “modified fibres” refers to one or both of the polymeric fibre and the fabric as a whole having undergone a chemical or physical process such as, but not limited to, one or more of a copolymerisation with monomers or other polymers, a chemical grafting reaction to contact a chemical functional group with one or both the polymeric fibre and a surface of the fabric, a plasma treatment, a solvent treatment, for example, acid etching, and a biological treatment, for example, an enzyme treatment or antimicrobial treatment to prevent biological degradation. In some examples, the textile substrate is PVC-free. The term“PVC-free” means no polyvinyl chloride polymer or vinyl chloride monomer units are in the textile substrate. In some examples, the textile substrate is a synthetic polyester fibre or is formed from a synthetic polyester fibre. The textile substrate may contain both natural fibres and synthetic fibres. In some examples, the amount of synthetic fibres represents from about 20% to about 90% of the total amount of fibres. In some other examples, the amount of natural fibres represents from about 10% to about 80% of the total amount of fibres. In some examples, the textile substrate comprises natural fibres and synthetic fibres in a woven structure, the amount of natural fibres is about 10% of a total fibre amount and the amount of synthetic fibres is about 90% of the total fibre amount.

The textile substrate may further contain additives including, but not limited to, one or more of, for example, colorant (e.g., pigments, dyes, tints), antistatic agents, brightening agents, nucleating agents, antioxidants, UV stabilizers, fillers and lubricants. Alternatively, the textile substrate may be pre-treated in a solution containing the substances listed above before the target substrate, i.e., the textile substrate, is contacted with the printed film.

Examples of textiles include synthetic fabrics, such as polyethylene terephthalate (PET), nylon, and/or polyester. The synthetic fabric may be a woven or non-woven fabric. In one example, a PET substrate is coated, for example, on one (e.g., back or front) or both sides with a coating, such as nylon and/or polyester. An example of a two-side-coated PET fabric is Product code 7280N, available from Cole Fabrics Far East, which is a white dip-coated nylon/polyester blend taffeta with a slit edge.

In some examples, the target substrate comprises a fabric, for example a woven fabric, a knitted fabric or a non-woven fabric. A fabric may be a cloth made from yarn or fibres by weaving, knitting, felting or other techniques. In some examples, the target substrate comprises a fabric formed from yarns comprising material selected from polyester, polyamides, polyvinyl alcohols, lyocell, rayon, viscose, nylon, cotton, linen, flax, hemp, jute and wool, acetates, acrylic, elastane, silk or any combination thereof.

In some examples, the target substrate has a thickness of less than 100 pm, for example less than 90 pm, less than 80 pm, less than 70 pm, less than 60 pm, less than 50 pm, less than 40 pm, less than 30 pm, less than 20 pm, less than 15 pm. In some examples, the target substrate has a thickness of greater than 12 pm, for example greater than 15 pm, greater than 20 pm, greater than 30 pm, greater than 40 pm, greater than 50 pm, greater than 60 pm, greater than 70 pm, greater than 80 pm, greater than 90 pm.

In some examples, the target substrate is a textile or fabric substrate and has a thickness of 100 pm or more, for example, 1 10 pm or more, 120 pm or more, 130 pm or more, 140 pm or more, 150 pm or more, 160 pm or more, 170 pm or more, 180 pm or more, 190 pm or more, 200 pm or more.

In some examples, the target substrate is a textile or fabric substrate and has a thickness of 400 pm or less, for example, 390 pm or less, 380 pm or less, 370 pm or less, 360 pm or less, 350 pm or less, 340 pm or less, 330 pm or less, 320 pm or less, 300 pm or less.

In some examples, the target substrate is a textile or fabric substrate and has a thickness of 100 pm to 400 pm, for example, 1 10 pm to 390 pm, 120 pm to 380 pm, 130 pm to 370 pm, 140 pm to 360 pm, 150 pm to 350 pm, 160 pm to 340 pm, 170 pm to 330 pm, 180 pm to 320 pm, 190 pm to 310 pm, 200 pm to 300 pm.

EXAMPLES

The following illustrates examples of the materials, methods and related aspects described herein. Thus, these examples should not be considered to restrict the present disclosure, but are merely in place to teach how to make examples of compositions of the present disclosure. As such, a representative number of compositions and their method of manufacture are disclosed herein.

Liquid electrostatic ink composition

The liquid electrostatic ink composition used was Electroink™ 4.5 available from HP Indigo™. Electroink™ 4.5 comprises a 4:1 mixture of Nucrel™ 699 (a copolymer of ethylene and methacrylic acid, made with nominally 1 1 wt.% methacrylic acid, available from DuPont™) and A-C 5120™ (a copolymer of ethylene and acrylic acid with an acrylic acid content of 15 wt.% and an acid number of 1 12-130 KOH/g, available form Honeywell™). General process for printing a heat transferable image

Liquid electrostatic printing onto the polyether-based thermoplastic polyurethane was performed with an HP Indigo 6800 printing press. No primer and no corona treatment was used. This produced a heat transferable printed image (a.k.a. a printed film) comprising a paper support layer, a thermoplastic polyurethane film disposed on the paper support layer and a liquid electrostatically printed ink disposed on the thermoplastic polyurethane film.

Process 1 for heat transfer printing

The liquid electrostatically printed ink disposed on the thermoplastic polyurethane film was contacted with a fabric. Heat transfer printing was performed in a heat press at a temperature of 150°C to 200°C and a pressure of approximately 1 kg with a dwell time of 20 s to 30 s. The paper support layer was then removed. This produced a heat transfer printed fabric comprising fabric, a liquid electrostatically printed ink disposed on the fabric; and a thermoplastic polyurethane film disposed on the liquid electrostatically printed ink.

Process 2 for heat transfer printing

The paper support layer was removed from the printed film. The thermoplastic polyurethane film was contacted with a fabric. A protective layer (polyethylene terephthalate or backing paper) was contacted with the liquid electrostatically printed ink disposed on the thermoplastic polyurethane film. Heat transfer printing was performed in a heat press at a temperature of 150°C to 200°C with a dwell time of 20 s to 30 s. The protective layer was then removed. This produced a heat transfer printed fabric comprising a fabric, a thermoplastic polyurethane film disposed on the fabric; and a liquid electrostatically printed ink disposed on the thermoplastic polyurethane film.

Example 1

A polyether-based thermoplastic polyurethane film (film A, LB-GH-154) for which the lower limit of the melting range was 75°C (determined by dynamic mechanical analysis according to ASTM E1953 at a temperature ramp of 3°C/min and a constant frequency of 1 Hz) and having a thickness of approximately 100 pm was used. The polyether- based thermoplastic polyurethane film was disposed on a support layer comprising a paper liner.

Reference Example 1

A polyester-based thermoplastic polyurethane film (film B, available from Novotex under the name FKS8558) with a bilayer structure in which the individual layers have melting points of 85°C and 165°C and the bilayer film has a thickness of approximately 100 pm was used. The layer onto which the liquid electrostatic ink composition was printed is the lower melting point layer (which has a melting point of 85°C). The polyester-based thermoplastic polyurethane film is disposed on a support layer comprising a paper liner.

Reference Example 2

A polyether-based thermoplastic polyurethane film (film C, available from Covestro under the name Dureflex PT9500) with a softening point of 133°C (TMA onset) to 153°C (TMA endpoint) measured according to ASTM E2347-04 and a thickness of approximately 100 pm was used. The melting range of this film is 120°C to 150°C as measured by dynamic mechanical analysis according to ASTM E1953 at a temperature ramp of 3°C/min and a constant frequency of 1 Hz. The polyether-based thermoplastic polyurethane film is disposed on a support layer comprising a paper liner.

Results - Liquid electrostatic printing on TPU

Heat transferable printed images were successfully formed by printing on films A (Example 1) and B (Reference Example 1). When liquid electrostatically printing on film C (Reference Example 2), the liquid electrostatic ink composition did not transfer from the ITM blanket of the printing press onto the polyether-based thermoplastic polyurethane film. Printing results are shown in Table 1 below.

Without wishing to be bound by theory, it is believed that the adhesion of the liquid electrostatic ink composition to film C (Reference Example 2) is reduced because the thermoplastic polyurethane film has a melting point (e.g., the lower limit of the melting range) and associated softening point that is too much higher than those of the thermoplastic resins in the liquid electrostatic ink composition. In contrast, films A and B both have melting points (e.g., the lower limit of the melting range) and softening points that are comparable to those of the thermoplastic resins of the liquid electrostatic ink composition.

Temperature-dependent dynamic mechanical analysis (DMA) measurements were performed to characterize the viscoelasticity of films A (Example 1) and C (Reference Example 2). Results are shown in Figures 2 to 4 (Figure 2 - resin of the liquid electrostatic ink composition; Figure 3 - film A, Figure 4 - film C).

In a temperature range of 25°C to 75°C, the polyether-based thermoplastic polyurethane of film A (Example 1) was found to be more elastic than viscous (G'>G"), indicating that the stored energy in the structure prevails over the energy that was dissipated by viscous forces. In addition, the storage modulus progressively decreases with applied temperature, which is typical for a thermoplastic polymer. At temperatures above 75°C, this trend changed with a sharp increase in tan d recorded from 0.2 to 0.8 corresponding to melting (phase transition) of the polymer - reflected by the drastic increase in this parameter. A higher tan d is indicative of a soft material that has a higher elastic strain component, whereas a low value indicates one that is more elastic.

DMA of the resins of the liquid electrostatic ink composition show more elastic than viscous behaviour up to about 80°C (G'>G") and the tan d peak is at temperatures above 70°C. Above 80°C, the resins of the liquid electrostatic ink composition are in a freely flowing melted state. Thus, the thermomechanical properties of the liquid electrostatic ink resins and the polyether-based thermoplastic polyurethane of film A (Example 1) are similar. As a result, adhesion between and fusion of the ink resin and film A (Example 1) is strong.

In contrast, the DMA profile of film C (Reference Example 2) demonstrates that at all temperatures tested, the polyether-based thermoplastic polyurethane of film C was found to be more elastic than viscous (G'>G"). Only at temperatures above 120°C was a dramatic rise in tan d observed, indicating that softening of this film only occurs at very high temperatures (above 120°C). As a result, at the temperatures used in liquid electrophotographic printing (about 1 10°C), the polyether-based thermoplastic polyurethane of film C was not softened enough to adhere properly.

Results - Adhesion to fabric

No difference in adhesion to fabric was observed for processes 1 and 2.

The results are summarized in table 1. The fabric used for the results in table 1 was a 100% cotton stretched T-shirt. The same results were also observed for an 80% cotton, 20% polyester T-shirt.

Adhesion to the fabric was tested by hand. Good adhesion means that it was impossible to detach the printed thermoplastic polyurethane film from the fabric after the lamination.

Adhesion of the liquid electrostatic ink composition to the thermoplastic polyurethane film was tested with the peeling test procedure in ASTM F2252.

The washing tests were performed in a washing machine (Electrolux EWF1074EMW) by using a 60°C cotton washing cycle over 135 min at 800 rpm. The fabric was then dried in a tumble dryer (Indesit IDCA 735) on a 3 h drying cycle.

Table 1

The TPU film A (Example 1) has a low softening point (below 75°C, DMA graph is similar to resin of LEP ink) and shows a high intensity response from free urethane and urea groups (1700-1730cm ¹) in an ATR-FTIR spectrum (Figure 5; film A - LB-GH-154; film B - N-85; film C - C-1). As a result, film A (Example 1 binds strongly to the liquid electrostatic ink composition and to the fabric, and is resistant to washing processes.

The TPU film C (Reference Example 2) has a high softening temperature (above 120°C) and a low intensity response from free urethane and urea groups in an ATR

FTIR spectrum. As a result, this film cannot be liquid electrostatically printed.

The TPU film B (Reference Example 1) shows good printability and good adhesion of the ink to the fabric. However, the bonding is not strong enough and it has limited resistance to washing. Without wishing to be bound by theory, it is believed that the ester bonds in the polyester-based thermoplastic polyurethane film react with water during washing, causing damage to the printed fabric and removing the ink from the fabric. While the methods, printed substrates and related aspects have been described with reference to certain examples, those skilled in the art will appreciate that various modifications, changes, omissions, and substitutions can be made without departing from the spirit of the disclosure. It is intended, therefore, that the methods, printed labels and related aspects be limited by the scope of the following claims. Unless otherwise stated, the features of any dependent claim can be combined with the features of any of the other dependent claims, and any other independent claim.

Claims

1. A process for heat transfer printing, the process comprising:

wherein the lower limit of the melting range of the polyether-based thermoplastic polyurethane film is 70°C to 90°C.

2. The process for heat transfer printing according to claim 1 , wherein the softening point of the polyether-based thermoplastic polyurethane film is in the range of 70°C to 80°C.

3. The process for heat transfer printing according to claim 1 , wherein contacting the printed film with the target substrate comprises contacting the polyether- based thermoplastic polyurethane film with the target substrate.

4. The process for heat transfer printing according to claim 3, wherein the polyether- based thermoplastic polyurethane film comprises a support layer and the support layer is removed from the polyether-based thermoplastic polyurethane film before the printed film is contacted with the target substrate.

5. The process for heat transfer printing according to claim 3, wherein a protective layer is contacted with the liquid electrostatically printed ink before the printed film is contacted with the target substrate.

6. The process for heat transfer printing according to claim 1 , wherein contacting the printed film with the target substrate comprises contacting the liquid electrostatically printed ink with the target substrate.

7. The process for heat transfer printing according to claim 6, wherein the polyether- based thermoplastic film comprises a support layer and the support layer is removed from the polyether-based thermoplastic polyurethane film after the printed film is contacted with the target substrate.

8. The process for heat transfer printing according to claim 1 , wherein the target substrate is fabric.

9. The process for heat transfer printing according to claim 1 , wherein contacting the polyether-based thermoplastic polyurethane film with a target substrate occurs at a temperature of 100°C or more.

10. The process for heat transfer printing according to claim 9, wherein the temperature of 100°C or more is applied for 1 minute or less.

1 1. The process for heat transfer printing according to claim 1 , wherein the polyether- based thermoplastic polyurethane film comprises urethane groups and urea groups.

12. The process for heat transfer printing according to claim 1 , wherein the polyether- based thermoplastic polyurethane film comprises a copolymer of:

a polyisocyanate;

a polyether polyol; and

13. A process for printing a heat transferable image, the process comprising:

14. A heat transferable printed image comprising:

a polyether-based thermoplastic polyurethane film; and

15. The heat transferable printed image according to claim 14, wherein a support layer is disposed on the opposing side of the polyether-based thermoplastic polyurethane film from the liquid electrostatically printed ink.