Composition

Abstract

The present invention relates to a composition formed from a hot melt adhesive having a color forming compound mixed therein. The present invention further relates to a substrate or multi-layer substrate structure having the composition thereon or therein onto which the composition has been applied, and a method of forming a color and / or image on and / or within a substrate or multi-layer substrate structure using the composition.

Description

[Technical field]

[0001] The present invention relates to compositions for use in forming color and / or images on and / or within substrates or multi-layer substrate structures. The present invention further relates to substrates or multi-layer substrate structures having the compositions applied thereon and / or incorporated therein, as well as methods of forming color or images on and / or within such substrates or multi-layer substrate structures. [Background technology]

[0002] The use of laser-responsive compositions containing color-forming compounds to generate human and / or machine-readable images and variable information is known. After applying such laser-responsive compositions to a substrate, image(s) can be formed upon application of a suitable stimulus to the laser-responsive composition. The stimulus, such as radiation, affects the color-forming compound, causing it to display a color or color change in the area of ​​the composition where the stimulus is applied so that an image is formed.

[0003] In an unrelated technical field, hot melt adhesives are used to provide effective bonding of surfaces of the same or different substrates. Hot melt adhesives usually exist in solid form at room temperature, for example as sticks, blocks, beads, pellets, balls, rods, granules or powders. These hot melt adhesives are thermoplastic materials that are commonly utilized in devices such as thermal adhesive guns and thermal adhesive applicators. When used, the heating element of the device heats the hot melt adhesive above room temperature and melts it, i.e., liquefies it by heat, so that it can be transferred and applied, as needed, from the device to the surface of the substrate(s) to be bonded. These substrate surfaces are then brought into contact while the hot melt adhesive is fully melted and tacky, and as the hot melt adhesive cools to room temperature, it successfully bonds the substrate surfaces to each other. Thus, hot melt adhesives are well known as materials suitable for adhesion and bonding of substrate surfaces. Summary of the Invention

[0004] According to a first aspect of the present invention, there is provided a composition formed from a hot melt adhesive having a colour forming compound admixed therein, wherein the colour forming compound is selected from a leuco dye, and an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, and when the colour forming compound is a leuco dye: (a) the leuco dye is selected from 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-xanthene]-3-one and 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[5isobenzofuran-1(3H),9'-[9H]xanthene]-3-one; (b) the hot melt adhesive further has a thermal acid generator admixed therein, the thermal acid generator being selected from 1,1,1-tris(4-hydroxyphenyl)ethane (THPE), tri-n-butylammonium-4,4'-dioxo-4H,4'H-2,2'-spirobi[benzo[d][1,3,2]dioxaborinine]-2-uido, N,N-dibutylbutan-1-aminium bis[2-(hydroxy-kO)benzoate(2-)-kO]borate(1-), 4-hydroxy-4'-isopropoxydiphenylsulfone, (2,4-dihydroxyphenyl)phenylmethanone, 3-(3-tosylureido)phenyl-4-methylbenzenesulfonate, 3,4,5-trihydroxybenzoic acid propyl, and 4,4'-methanediyldiphenol; (c) the melting temperature of the hot melt adhesive is lower than the melting temperatures of both the leuco dye and the thermal acid generator; When the color-forming compound is an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, the melting temperature of the hot melt adhesive is lower than the decomposition temperature of the oxyanion of the polyvalent metal or an oxyacid or hydrate thereof.

[0005] According to a second aspect of the present invention, there is provided a composition formed from a hot melt adhesive having admixed therein a colour forming compound and an infrared absorbing compound, wherein the colour forming compound is selected from a leuco dye, or an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof; When the color forming compound is a leuco dye, the hot melt adhesive further has a thermal acid generator mixed therein, the melting temperature of the hot melt adhesive being lower than the melting temperatures of both the leuco dye and the thermal acid generator; When the color-forming compound is an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, the melting temperature of the hot melt adhesive is lower than the decomposition temperature of the oxyanion of the polyvalent metal or an oxyacid or hydrate thereof.

[0006] According to a third aspect of the present invention, there is provided a composition formed from a hot melt adhesive having a color forming compound mixed therein, wherein the color forming compound is selected from ammonium octamolybdate and the following leuco dyes: 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-xanthene]-3-one, and 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[5isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, and when the color forming compound is a leuco dye, the hot melt adhesive further has a thermal acid generator 1,1,1-tris(4-hydroxyphenyl)ethane mixed therein.

[0007] According to a fourth aspect of the invention, there is provided a substrate comprising a composition according to the first, second or third aspect of the invention, having the composition applied thereon.

[0008] According to a fifth aspect of the present invention there is provided a multi-layer substrate structure comprising a composition according to the first, second or third aspects of the present invention, having the composition applied thereon and / or incorporated therein.

[0009] According to a sixth aspect of the present invention there is provided a method of forming a composition according to the first, second or third aspect of the present invention, the method comprising the steps of heating the hot melt adhesive to a temperature equal to or higher than the melting temperature of the hot melt adhesive but lower than the melting or decomposition temperature of the colour forming compound and, if present, the melting temperature of the thermal acid generator or the infrared absorbing compound, so that the hot melt adhesive melts, and mixing the colour forming compound and optionally the thermal acid generator and the infrared absorbing compound in the molten hot melt adhesive so that they are distributed throughout the molten hot melt adhesive.

[0010] According to a seventh aspect of the present invention, there is provided a method of forming a substrate comprising a composition according to the first, second or third aspect of the present invention, onto which the composition has been applied, the method comprising the steps of heating the composition to a temperature equal to or above the melting temperature of the hot melt adhesive but below the melting or decomposition temperature of the colour forming compound and, if present, the melting temperature of the thermal acid generator or infrared absorbing compound, such that the hot melt adhesive melts; once the hot melt adhesive is melted, applying the composition to the substrate; and allowing the composition to cool and solidify on the substrate.

[0011] According to an eighth aspect of the present invention, there is provided a method of forming a multi-layer substrate structure comprising a composition according to the first, second or third aspect of the present invention, onto which said composition has been applied, the method comprising the steps of heating the composition to a temperature equal to or above the melting temperature of the hot melt adhesive but below the melting or decomposition temperature of the colour forming compound and, if present, the melting temperature of the thermal acid generator or infrared absorbing compound, such that the hot melt adhesive melts; once the hot melt adhesive is melted, applying the composition to a substrate; and allowing the composition to cool and solidify.

[0012] According to a ninth aspect of the present invention, there is provided a method of forming a multi-layer substrate structure having a composition according to the first, second or third aspects of the present invention, the composition being incorporated therein, the method comprising the steps of heating the composition to a temperature equal to or above the melting temperature of the hot melt adhesive but below the melting or decomposition temperature of the colour forming compound and, if present, the melting temperature of the thermal acid generator or infrared absorbing compound, such that the hot melt adhesive melts; once the hot melt adhesive is melted, applying the composition to a substrate; and contacting the substrate with another substrate with the composition located therebetween, such that the substrates are bonded together by the composition to form a multi-layer substrate structure.

[0013] According to a tenth aspect of the present invention there is provided a method of forming a colour and / or image on a substrate comprising a composition according to the first, second or third aspect of the present invention onto which the composition has been applied, the method comprising the step of applying radiation to the composition as appropriate so as to form a colour and / or image on the substrate.

[0014] According to an eleventh aspect of the present invention there is provided a method of forming colour and / or an image on and / or in a multi-layer substrate structure comprising a composition according to the first, second or third aspect of the present invention, onto which said composition has been applied and / or within which said composition has been incorporated, the method comprising the step of applying radiation to the composition as appropriate so as to form colour and / or an image on and / or in the multi-layer substrate structure.

[0015] According to a twelfth aspect of the present invention there is provided the use of a composition according to the first, second or third aspect of the present invention in the formation of a colour and / or image.

[0016] According to a thirteenth aspect of the present invention there is provided the use of a composition according to the first, second or third aspect of the present invention in the formation of a colour and / or image on a substrate having said composition, said substrate having said composition applied thereon.

[0017] According to a fourteenth aspect of the present invention there is provided the use of a composition according to the first, second or third aspect of the present invention in the formation of a colour and / or image on and / or within a multi-layer substrate structure having said composition, said multi-layer substrate structure onto which the composition has been applied and / or within which the composition has been incorporated. [Brief description of the drawings]

[0018] [Figure 1] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Diagram 2] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Diagram 3] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 4] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Diagram 5] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 6] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 7] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 8] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 9] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 10]1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 11] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 12] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 13] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 14] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 15] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 16] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 17] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 18] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 19] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 20] 1 illustrates color and image formation of compositions according to the first, second and third aspects of the invention, and on a substrate according to the fourth aspect of the invention. [Figure 21] 1 shows a comparative composition not according to the invention: Color and / or images cannot be formed upon subsequent application of radiation when using such a composition. [Figure 22] 1 shows a comparative composition not according to the invention: Color and / or images cannot be formed upon subsequent application of radiation when using such a composition. [Figure 23] 1 shows a comparative composition not according to the invention: Color and / or images cannot be formed upon subsequent application of radiation when using such a composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] It has been surprisingly and advantageously discovered that hot melt adhesives can be advantageously utilized for other purposes in addition to adhering and bonding substrate surfaces. The inventors have advantageously determined that hot melt adhesives can be utilized to transfer color forming compounds to a substrate or multi-layer substrate structure to provide the substrate or multi-layer substrate structure with the ability to display color and / or images. The present invention has particular application in the packaging and printing industry, particularly for forming variable information images on the exterior of a package. The present invention exhibits numerous benefits and advantages over known printing and packaging techniques, as discussed in more detail below.

[0020] Surprisingly and advantageously, it has been found that color-forming compounds can be incorporated into hot melt adhesives to form compositions that can be applied to substrates or multi-layer substrate structures or used to form multi-layer substrate structures, and subsequently exposed to radiation, preferably from a laser light source(s), to form color and / or images on and / or within the substrate or multi-layer substrate structure. Non-coloring, meaning that color and / or image formation cannot occur with subsequent application of radiation, occurs during the fabrication of the composition or during application of the composition to the substrate and / or multi-layer substrate structure, prior to a particular application of radiation. The composition can advantageously be applied to either the outer surface of the substrate or multi-layer substrate structure to facilitate the formation of color and / or image thereon, and / or can be used to bond two substrates of a multi-layer substrate structure to each other and facilitate the formation of color and / or image therein.

[0021] In forming the composition according to the invention, the hot melt adhesive requires heating from room temperature so that it melts for effective mixing, fabrication of the color forming compound and its incorporation to occur inside. Furthermore, the hot melt adhesive of the composition according to the invention requires heating to melt and allow the composition to be applied to a substrate(s) or multi-layer substrate structure(s) and / or to be used to form a multi-layer substrate structure(s). For this purpose, heating of the composition to a temperature above room temperature is required.

[0022] Therefore, it is certainly surprising that, for the composition of the present invention, during this heating of the composition above room temperature so that it melts, i.e. during the fabrication, processing, and application of the composition to the substrate(s) or multi-layer substrate structure, and / or during its use in forming a multi-layer substrate structure, the color-forming compound mixed into the hot melt adhesive is not affected by the temperature increase, and the desired color and / or image formation on and / or in the substrate or multi-layer substrate structure can be initiated with a specific and controlled application of radiation, preferably using a laser source, following the application of the composition to the substrate or multi-layer substrate structure, and / or after its use in forming a multi-layer substrate structure. Thus, advantageously, a controlled generation of a human and / or machine readable image, in particular a human and / or machine readable variable information image, is achieved. This is particularly surprising, since color-forming compounds are usually heat sensitive. In particular, color-forming compounds such as leuco dyes usually have low heat sensitivity. Therefore, it is surprising to the inventors that color-forming compounds, including leuco dyes, which require heating during fabrication, processing, and application, can be utilized in the composition of the present invention.

[0023] Surprisingly and advantageously, it has been found that the properties of the compositions of the present invention allow them to be applied directly to a substrate(s) or multi-layer substrate structure(s) and / or used to form a multi-layer substrate structure(s) without the need for dilution. Many printing processes for laser-responsive color-forming compositions, such as those that require low-viscosity liquid formulations, involve dilution of the composition before application to a substrate(s). This can negatively affect the active solids concentration of the color-forming compound(s) and therefore the optical density of the color and / or image formed upon exposure to radiation. However, for the compositions of the present invention, the concentration of the color-forming compound in the composition does not change and remains sufficiently high without dilution, so that high optical density colors and / or images can be achieved.

[0024] Still further, many printing processes for known laser-reactive color-forming compositions utilize printing machines, which can generate a significant amount of waste, i.e., unused composition. Furthermore, known processes used to apply laser-reactive color-forming compositions can usually only apply layers of the composition to a substrate at low coating weights. If a significant number of layers of the composition are not applied, insufficient color-forming compounds will be transferred to the substrate, resulting in poor, low-quality color and / or image formation with low optical density. The composition of the present invention eliminates these problems and provides an easier, more reliable method to effectively form color and / or image on a substrate.

[0025] Furthermore, it has been surprisingly and advantageously found that the composition of the present invention can exhibit improved color and image stability over time, even when present on the outer surface of a substrate or multi-layer substrate structure and exposed to environmental conditions. The hot melt adhesive of the composition is hydrophobic and insoluble in water, so moisture is excluded from it. This allows the composition of the present invention to exhibit increased environmental resistance to factors such as high humidity or wet conditions at room temperature, and to maintain high optical density color and / or image over time. This is particularly advantageous when the composition serves as a label and is exposed on the outside of a substrate or multi-layer substrate structure, such as a packaging substrate.

[0026] It has further surprisingly and advantageously been found that applying the composition of the present invention directly onto and / or into a substrate or multi-layer substrate structure allows for the formation of an integrated label in a packaged product. The label may be exposed on the outer surface of the substrate or multi-layer substrate structure and / or incorporated into the multi-layer substrate structure so that it is exposed. The addition of variable information to the product not only provides an attractive appearance to the packaged product, but it is also desirable for tracking, tagging, and tracing the product. The integrated label and the variable information it displays cannot be intentionally or accidentally removed from the product (which would be detrimental to the product's identification, since the information attributed to the product by the label would be lost). Thus, there is an added security benefit by integrating the label into the packaging.

[0027] Even more surprisingly and advantageously, it has been found that the compositions of the present invention exhibit improved environmental and sustainability credentials. In such cases, the hot melt adhesive of the compositions of the present invention may be formed from recyclable, biodegradable and / or compostable materials. When the compositions of the present invention, including such recyclable, biodegradable and / or compostable materials, are applied directly onto or into similarly recyclable, biodegradable and / or compostable substrates and / or multi-layer substrate structures, it allows the formation of a substrate that can be recycled, biodegraded or composted as a whole. Thus, when the hot melt adhesive is formed from biodegradable and / or compostable materials, such as bioplastic materials, and the substrate or multi-layer substrate structure to which the composition is applied and / or incorporated within is also similarly biodegradable and / or compostable, e.g. cardboard, paperboard or bioplastic materials, the compositions of the present invention exhibit special environmental and sustainability advantages. In such cases, the entire product with the label displaying the integrated variable information is biodegradable and / or compostable.

[0028] As used herein, the term "room temperature" refers to a temperature between 10 and 35°C, typically between 18 and 28°C. Room temperature is encompassed by the broader definition of "ambient conditions" and refers to the normal range of conditions in the surrounding environment to which the composition is exposed, i.e., the range of temperature, pressure and atmospheric conditions to which the composition is exposed during use, storage and otherwise. This includes sunlight, including X-ray, ultraviolet (UV) and infrared (IR) electromagnetic radiation. Typically, ambient conditions include a temperature between 10 and 35°C, a pressure between 20 and 100 kPa, and the environment is typically an oxygen-containing atmosphere.

[0029] According to a first aspect of the present invention, there is provided a composition formed from a hot melt adhesive having a colour forming compound admixed therein, wherein the colour forming compound is selected from a leuco dye, and an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, and when the colour forming compound is a leuco dye: (a) the leuco dye is selected from 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-xanthene]-3-one and 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[5isobenzofuran-1(3H),9'-[9H]xanthene]-3-one; (b) the hot melt adhesive further has a thermal acid generator admixed therein, said thermal acid generator being selected from 1,1,1-tris(4-hydroxyphenyl)ethane (THPE), tri-n-butylammonium-4,4'-dioxo-4H,4'H-2,2'-spirobi[benzo[d][1,3,2]dioxaborinine]-2-uido, N,N-dibutylbutan-1-aminium bis[2-(hydroxy-kO)benzoato(2-)-kO]borate(1-), 4-hydroxy-4'-isopropoxydiphenylsulfone, (2,4-dihydroxyphenyl)phenylmethanone, 3-(3-tosylureido)phenyl-4-methylbenzenesulfonate, 3,4,5-trihydroxybenzoic acid propyl, and 4,4'-methanediyldiphenol; (c) the melting temperature of the hot melt adhesive is lower than the melting temperatures of both the leuco dye and the thermal acid generator; When the color-forming compound is an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, the melting temperature of the hot melt adhesive is lower than the decomposition temperature of the oxyanion of the polyvalent metal or an oxyacid or hydrate thereof.

[0030] According to a second aspect of the present invention there is provided a composition formed from a hot melt adhesive having admixed therein a colour forming compound and an infrared absorbing compound, wherein the colour forming compound is selected from a leuco dye or an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof; When the color forming compound is a leuco dye, the hot melt adhesive further has a thermal acid generator mixed therein, the melting temperature of the hot melt adhesive being lower than the melting temperatures of both the leuco dye and the thermal acid generator; When the color-forming compound is an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, the melting temperature of the hot melt adhesive is lower than the decomposition temperature of the oxyanion of the polyvalent metal or an oxyacid or hydrate thereof.

[0031] According to a third aspect of the present invention, there is provided a composition formed from a hot melt adhesive having a color forming compound mixed therein, wherein the color forming compound is selected from ammonium octamolybdate and the following leuco dyes: 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-xanthene]-3-one, and 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[5isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, and when the color forming compound is a leuco dye, the hot melt adhesive further has a thermal acid generator 1,1,1-tris(4-hydroxyphenyl)ethane mixed therein.

[0032] Hot melt adhesives are known in the art. A hot melt adhesive is a thermoplastic adhesive material that is solid at room temperature, but upon application of heat, it transitions from a solid state to a molten state and is capable of flowing. It returns to a solid state when cooled to room temperature. The term "melt" in reference to a hot melt adhesive means that the hot melt adhesive is capable of flowing. It may be viscous, but it is capable of flowing. To melt, the hot melt adhesive is heated above its melting temperature. The melting temperature of a hot melt adhesive is the temperature at which the hot melt adhesive melts and is capable of flowing. It is the temperature at which the hot melt adhesive transitions from a solid state to a viscous, flowing state. This is sometimes known in the art as the softening temperature. It is understood that this melting temperature is the effective minimum processing temperature of the hot melt adhesive. In the context of the present invention, those skilled in the art will recognize that there is a melting temperature range within which a hot melt adhesive will typically melt and therefore be capable of flowing. This can occur, for example, when the hot melt adhesive comprises multiple thermoplastic polymers, copolymers, oligomers, as discussed below. A hot melt adhesive thus melts above its melting temperature, but is solid at room temperature. When melted, a hot melt adhesive is tacky. When melted, it can therefore act as an adhesive or be easily applied to a substrate(s). When melted, a hot melt adhesive can be tacky, but when cooled and solid at room temperature, it is non-tacky (commonly known in the industry as a non-pressure sensitive hot melt adhesive), or it is tacky when melted and remains tacky when cooled and solid at room temperature (commonly known in the industry as a pressure sensitive hot melt adhesive).

[0033] Hot melt adhesives and their components are well known in the art. For example, "Sustainable Raw Materials in Hot Melt Adhesives: A Review; Vineeth et al.; Open Journal of Polymer Chemistry; Vol. 10, No. 3; August 2020" and "Basic Study of Evaluation of Thermoplastic Polymers as Hot-Melt Adhesives for Mixed-Substrate Joining; Open Journal of Polymer Chemistry; Col. 6, No. 8; August 2016" discuss hot melt adhesives.

[0034] In the context of the present invention, it is understood that the hot melt adhesive serves as a vehicle for the transfer of color forming compounds onto and / or into a substrate or multi-layer substrate structure upon which color and / or images may be formed.

[0035] The hot melt adhesive of the composition of the first, second or third aspect of the present invention comprises a thermoplastic polymer, copolymer, oligomer or mixture thereof as a base material. Usually, the hot melt adhesive further comprises a tackifier or resin. Usually, the hot melt adhesive also further comprises one or more additive components as described below. Preferably, the hot melt adhesive further comprises a tackifier or resin. Preferably, the hot melt adhesive further comprises one or more additive components.

[0036] The thermoplastic polymer, copolymer, oligomer or mixture thereof of the hot melt adhesive may be selected from, but is not limited to, the following: poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymer; poly(ethylene acrylate) copolymer; acrylic resin; polyvinyl butyral; polyolefins, such as polybutene, including low density (LDPE), medium density (MDPE) and high density (HDPE) polyethylene, polyethylene, and polypropylene; polyamides, such as ethylenediamine and hexamethylenediamine; nylon; polyesters, including poly(lactic acid) (PLA), polyethylene terephthalate (PET), polyhydroxyalkanoates (PHAs), and poly(glycolic acid) (PGA); polyurethanes; acrylics and styrene acrylate copolymers; styrene-isoprene-styrene block tri- and copolymers; polystyrene (PS); polycaprolactone; polycarbonate; fluoropolymers; elastomers; silicone rubber and polypyrrole, or combinations thereof.

[0037] The thermoplastic polymer, copolymer or oligomer may be a petroleum-based thermoplastic polymer, copolymer or oligomer, or a bioplastic thermoplastic polymer, copolymer or oligomer. Preferably, the thermoplastic polymer, copolymer or oligomer is a bioplastic thermoplastic polymer, copolymer or oligomer. Bioplastic thermoplastic polymers, copolymers or oligomers encompassed herein include, but are not limited to: poly(lactic acid) (PLA), polyhydroxyalkanoates (PHA) and poly(glycolic acid) (PGA), and poly(ethylene-vinyl acetate) or ethylene-vinyl acetate (EVA) copolymers when formed from ethanol derived from sugarcane and / or other natural sources, and polyethylene when formed from sugarcane and / or other natural sources. With respect to thermoplastic polymers, copolymers, oligomers or mixtures thereof, for the poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymers and polyethylene materials listed herein, both bioplastic and petroleum-based plastic forms are encompassed.

[0038] As used herein, the prefix "petroleum-based plastic" refers to any material derived from a petrochemical origin(s). Such materials are typically recyclable. Thus, they are typically made from either virgin or recovered materials, or a combination thereof.

[0039] As used herein, the prefix "bioplastic" refers to any material derived from natural and sustainable sources. Such materials are typically recyclable, biodegradable and / or compostable, especially biodegradable and / or compostable. Thus, they are typically made from either virgin or recovered materials, or a combination thereof.

[0040] Preferably, the thermoplastic polymer, copolymer, oligomer or mixtures thereof are recyclable, biodegradable and / or compostable.

[0041] Preferably, the thermoplastic polymer, copolymer, oligomer or mixture thereof is selected from polyethylene terephthalate (PET), polyhydroxyalkanoate (PHA), poly(glycolic acid) (PGA), poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymer, low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), and poly(lactic acid) (PLA). More preferably, the thermoplastic polymer, copolymer, oligomer or mixture thereof is selected from polyhydroxyalkanoate (PHA), poly(glycolic acid) (PGA), poly(ethylene-vinyl acetate) or ethylene-vinyl acetate (EVA) copolymer, and low density polyethylene (LDPE). More preferably, the thermoplastic polymer, copolymer, oligomer or mixture thereof is selected from polyhydroxyalkanoate (PHA), poly(glycolic acid) (PGA), and poly(ethylene-vinyl acetate) or ethylene-vinyl acetate (EVA) copolymer. Most preferably, the thermoplastic polymer, copolymer or oligomer is poly(ethylene-vinyl acetate) or ethylene-vinyl acetate (EVA) copolymer.

[0042] The thermoplastic polymer, copolymer, oligomer or mixture thereof may be present in the hot melt adhesive in any suitable amount. Preferably, the thermoplastic polymer, copolymer, oligomer or mixture thereof is present in an amount of 20-90%, such as 30-80% or 40-75% of the hot melt adhesive.

[0043] The thermoplastic polymer, copolymer, oligomer or mixture thereof may be present in the composition of the first, second or third aspect of the invention in any suitable amount. Preferably the thermoplastic polymer, copolymer, oligomer or mixture thereof is present in an amount of from 10 to 90%, such as from 20 to 70% or even from 25 to 60% of the composition.

[0044] The hot melt adhesive of the composition of the first, second or third aspect of the present invention may further comprise a tackifier or resin. Preferably, the hot melt adhesive of the composition of the first, second or third aspect of the present invention comprises a tackifier or resin. It is understood that more than one tackifier or resin may be present.

[0045] The tackifier or resin may contain acid, hydroxyl or ester functional groups. Preferably, the tackifier or resin contains acid or ester functional groups. If the tackifier or resin contains acid functional groups, the tackifier or resin preferably has an acid number of 5 to 250, for example 5 to 200.

[0046] Suitable tackifiers or resins include, but are not limited to, resins including natural resins such as copal, dammar, mastic and sandarac; petroleum resins; rosins and their derivatives such as rosin, rosin acids, rosin esters and rosin resins--gum rosin, wood rosin or tall oil rosin; hydrogenated rosins such as Foral AX and Foral AX-E rosins from Eastman Chemical Companies; dimerized rosin resins; modified rosin resins; terpenes and modified terpenes; aliphatic, cycloaliphatic and aromatic resins such as C5 aliphatic resins, C9 aromatic resins and C5 / C9 aromatic / aliphatic resins; hydrogenated hydrocarbon resins; terpene phenolic resins; polybutenes and polyisobutenes; and combinations thereof. Commercially available examples of tackifiers or resins include "Piccotac 1020-E Hydrocarbon Resin", "Piccotac 1095-N Hydrocarbon Resin", "Piccotac 9095 Hydrocarbon resin", and "Piccotac 8095 Hydrocarbon resin" available from Eastman Chemical Companies. Preferably, the tackifier or resin is selected from rosin and its derivatives, hydrogenated rosin, dimerized rosin resin, and modified rosin resin.

[0047] The tackifier or resin may be present in any suitable amount in the hot melt adhesive of the composition of the first, second or third aspect of the present invention. Preferably, the tackifier or resin, if present, is present in an amount of from 1 to 90% of the hot melt adhesive, such as from 2 to 80%, or from 5 to 70%, or from 10 to 60%.

[0048] The tackifier or resin may be present in the composition of the first, second or third aspect of the invention in any suitable amount. Preferably the tackifier or resin, if present, is present in an amount of from 10 to 90%, from 15 to 80%, from 20 to 70%, preferably from 25 to 60% of the composition.

[0049] The hot melt adhesive of the composition of the first, second or third aspect of the present invention may further comprise one or more additive components. Preferably, the hot melt adhesive comprises one or more additive components. Suitable additive components are well known to those skilled in the art. These additive components are usually present to manage the rheological properties, such as the viscosity of the hot melt adhesive, and thereby the composition. Examples of suitable additive components include, but are not limited to: waxes, such as fatty acid amide waxes, oxidized fischer-tropsch waxes or waxes derived from both Fischer-Tropsch and Zigler-Natta processes, water-soluble waxes, polyalkylene waxes, mineral waxes such as paraffin and microcrystalline waxes, polyethylene waxes, polyethylene glycol waxes (Carbowax from DOW Chemical Inc.), oxidized polyethylene waxes, N,N'-ethylene bisstearamide (Lonza Inc.bisstearamides such as Acrawaz from Eastman Chemical Corporation, natural and synthetic waxes such as beeswax, soy wax, carnauba, ozokerite and ceresin, and silicone waxes; slip agents; lubricants; inhibitors; antioxidants; stabilizers such as Irganox 1010; UV stabilizers and UV absorbers such as the Tinuvin series including Tinuvin 770, 928 326, 1130, (384-2) and 123, and combinations thereof (BASF); adhesion promoters; plasticizers such as glyceryl tribenzoate, alkyl benzoates and benzoic acid esters (e.g. Benzoflex from Eastman Chemical Corporation). 9-88), glycols such as diethylene glycol, C12-15 alkyl benzoates, C2-C22 alkyl benzoates, alkyl citrates, phthalates, phthalate esters, paraffin oil, and polyisobutylene;light or energy absorbers;surfactants;wetting agents, such as esters such as polyhydroxystearic acid, polyglyceryl-4 isostearate, hexyl laurate, isopropyl myristate, propylene carbonate, isononyl isononanoate, glyceryl behenate / eicosadiate, trihydroxystearin, Cl2-15 alkyl benzoates, C2-C22 alkyl benzoates (where the alkyl groups are linear or branched or mixtures thereof), triethoxycaprylylsilane, castor oil;drying accelerators;colorants such as pigments;flame retardants;antistatic agents;fillers;colorants;viscosity modifiers;fluorescent agents;optical brighteners;oxidizing or reducing agents;stabilizers;Tinuvin 292; rheology modifiers such as thickeners or deviscosifiers; matting agents; active clays; anti-settling agents; anti-sagging agents; dispersants; surface modification additives; slip agents; leveling agents; fillers; humectants; adhesion promoters; acid or base scavengers; retarders; defoamers; surfactants; antifoaming agents; biocides; preservatives; antioxidants such as BHT, phosphites and phosphates; antimicrobial agents; antiviral agents; antibacterial agents; antifungal agents; mildewcides; bactericides; disinfectants; and combinations thereof. Typically, hot melt adhesives further comprise one or more additive components selected from waxes, plasticizers, antioxidants, UV stabilizers and fillers or combinations thereof. .

[0050] The one or more additive components may be present in the hot melt adhesive of the composition of the first, second or third aspect of the present invention in any suitable amount. Preferably, if present, the one or more additive components are present in an amount of 0.1 to 35%, such as 0.1 to 30%, or 0.1 to 25% or 0.1 to 20% of the hot melt adhesive.

[0051] The one or more additive components may be present in the composition of the first, second or third aspect of the invention in any suitable amount. Preferably, the one or more additive components, if present, are present in an amount of from 0.1 to 35%, such as from 0.1 to 30%, or even from 0.1 to 25%, such as from 0.1 to 20%, of the composition.

[0052] Those skilled in the art will recognize that hot melt adhesives may be purchased commercially or formulated from suitable starting materials. Hot melt adhesives and their components are well known in the art. Those skilled in the art can easily identify the appropriate hot melt adhesive or required components, such as thermoplastic polymers, oligomers, copolymers or mixtures thereof, tackifiers or resins, and one or more additive components, depending on the desired properties of the hot melt adhesive in question. Furthermore, it is understood that hot melt adhesives and hot melt adhesive materials known in the art, such as those utilized in glue guns and thermal glue applicators, are suitable for use in the present invention. Such materials are known by those skilled in the art.

[0053] Commercially available thermoplastic polymers, copolymers, oligomers or mixtures thereof suitable for hot melt adhesives include, but are not limited to, poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymers available from ExxonMobil under the trade name "Escorene™ Ultra"; Rowak under the trade name "Rowalit® 300"; and Evatane as "SK Functional Polymers"; Versalis SpA Greenflex HN70 from Distrupol; polypropylene from Borealis under the trade name "RE 420"; and low density polyethylene available from Rowak under the trade name "Rowalit® H" and from Lyondell Basell under the trade name "Lupolen 1800S". Regarding bio-based hot melt adhesives, commercially available thermoplastic polymers, copolymers, oligomers or mixtures thereof include, but are not limited to, polylactic acid (PLA) known as Ingeo™ Biopolymer 3251D from Nature Works (Minnetonka, MN, USA).

[0054] Commercially available hot melt adhesives suitable for use in the compositions of the first, second and third aspects of the invention include, but are not limited to, hot melt adhesives such as those available from Henkel (Technomelt, Technomelt Cool, Technomelt Supra, Technomlet Supra Pro, Technomelt Pur, Technomelt PA, Technomelt DA, Easymelt and EasyFlow), Caswell Adhesives (Premiermelt or Casmelt products), Loctite, Bostik (Kizen, Kizen Force, Kizen ice, Kizen heat, Supergrip, Close TLH 4280E and TLH 2901E, Protect and Seal TLH 4492E, TLH 2299E, Send TLH 4280E, TLH 4119E, Track TLH 4000E, Show TLH 2211ELO, TLH 2299E, Hang TLH 2281E and TLH2211ELO, and TEF272), DuPont (ELVAX 40W, 150W, 210W, 220W, 240W, 250, 260, 265, 350, 360, 410, 420, 450, 460, 470, 550, 560, 660, 670, 750, 770, 4260, 4310, 4320, and 4355), Repsol (Primeva EVA's P1550M, P18150, P18500, P20020, P2430, P2735, P2870, P28025, P28150, P28400, P28045, P28800, P2850M, P2836M, P33015, P33025, P33045, P33400, P40055 (containing 15-40% VA) and Ebantix EBA's E1715, E1770, E20020, E27150, E33150 EBA (Ethylene Butyl Acrylate) (tackifier - used with rosin resins, polyterpene resins, cycloaliphatic resins), Technology Supplied Ltd ("Proflex 970 Hot Melt Glue Stick"), Tian Tian Adhesive Factory(``Hot melt gluestick"), Toolstream Ltd ("Hot melt Glue Stick", 698462, 652076, 349348, 100024), FPC Corporation ("Hot Melt Glue", 501, 601, 701, 702, 707, 708, 7011, 724) and 3M (Hot Melt Adhesive 3764, 3747, 3748, 3731, 3738, 3796, 3792, 3762, 3779 and 3789).

[0055] The hot melt adhesive of the composition according to the first, second or third aspect of the present invention may have any suitable melt flow index (MFI). The hot melt adhesive may have a melt flow index of 1 to 1000 g / 10 min, for example 3 to 900 g / 10 min or 10 to 900 g / 10 min. It will be appreciated by those skilled in the art that the melt flow index defines the flowability of the hot melt adhesive when melted above its melting temperature.

[0056] Methods for measuring the melt flow index (MFI) of hot melt adhesives are well known to those skilled in the art, and the values ​​may be measured according to ISO standard 1133-1 or ASTM D1238. It is understood by those skilled in the art that the term melt flow index may be used interchangeably with melt flow rate (MFR) or melt index (MI). Melt flow index is a measure of the flow rate of a thermoplastic material, such as a hot melt adhesive. It is defined as the mass (grams) of a thermoplastic material that flows through a capillary of a particular diameter and length in 10 minutes due to an applied pressure. In the context of the present invention, melt flow index is measured as a value that indicates the relative flow rate of hot melt adhesives and how they behave when heated to a temperature above room temperature where they can melt and flow. The melt flow index of a hot melt adhesive may be approximately inversely proportional to the molecular weight of the thermoplastic polymer, copolymer, oligomer, or mixture thereof of the hot melt adhesive. Melt flow index can be measured at different temperatures, different loads and different times, however, MFI is generally measured at temperatures of 190°C and / or 230°C, 2.16kg or 5kg weight for 10 minutes. For example, a standard test uses MFI equipment such as an Extruson Plastometer, 190°C, and 2.16kg weight for 10 minutes. The applied load provides the shear stress of the equipment.

[0057] The thermoplastic polymers, copolymers, oligomers or mixtures thereof of the hot melt adhesives may have any suitable molecular weight. Molecular weight can usually be indirectly estimated using MFI measurements, and those skilled in the art will recognize that a higher MFI generally corresponds to a lower molecular weight and vice versa.

[0058] The melting temperature of a hot melt adhesive may be 50-200°C, or 50-160°C, including 70-150°C. The melting temperature of a hot melt adhesive is the temperature at which the hot melt adhesive melts and can flow. It is the temperature at which the hot melt adhesive transitions from a solid state to a viscous flowable state. This may sometimes be known in the art as the softening temperature. It is understood that this melting temperature is effectively the minimum processing temperature of the hot melt adhesive. As discussed above, the melting temperature of a hot melt adhesive can span a melting temperature range. In the context of this invention, both endpoints of any melting temperature range are encompassed by the stated value for the melting temperature of the hot melt adhesive.

[0059] Suitable methods for measuring the melting temperature of hot melt adhesives are well known to those skilled in the art. The melting temperature can be measured by differential scanning calorimetry (DSC) using a melting point measuring device with a thermometer, or by the known "ring and ball" melting temperature measuring method. This may be according to ISO 4625-1:2020. In the "ring and ball" method, a layer of hot melt adhesive is placed in a steel ring and cooled. A ball that barely passes through the ring is placed on the hot melt adhesive layer. The whole system is placed in an oil bath and heated. The melting temperature is determined as the temperature at which the ball falls through the hot melt adhesive layer and touches the bottom of the oil bath. Preferably, the melting point of the hot melt adhesive is measured by DSC. This may be according to ISO 11357-1:2016.

[0060] DSC is a technique well known to those skilled in the art and is a thermal analysis technique in which the difference in the amount of heat energy required to change the temperature of a hot melt adhesive sample and a reference is measured as a function of temperature. The aim is for both the hot melt adhesive sample and the reference to maintain the same temperature so that DSC can determine the endothermic transition, i.e. the melting temperature, when the hot melt adhesive melts and becomes able to flow. The underlying principle of DSC is that if the hot melt adhesive sample undergoes a physical transformation, more heat energy will be required to keep both isothermal in order for the sample to flow compared to the reference. By measuring the difference in heat flow between the sample and the reference, DSC can determine the amount of heat absorbed during the endothermic transition.

[0061] It is understood that when melted, the hot melt adhesive, and thus the composition of the first, second or third aspect of the invention, is tacky. The "tack" of the hot melt adhesive, and thus the composition, may be measured according to ASTM 3121 ("Rolling Ball Tack").

[0062] When the thermoplastic polymer, copolymer, oligomer or mixture thereof of the hot melt adhesive is poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymer, it will be recognized by those skilled in the art that the ratio of vinyl acetate to ethylene in the copolymer may vary. For example, poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymer may contain 1-60% vinyl acetate, such as 10-40%, or even 15-33% vinyl acetate. Poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymer may contain 25% or more vinyl acetate. Poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymer may contain 24% or less vinyl acetate.

[0063] Those skilled in the art will recognize that changing the ratio of vinyl acetate and ethylene monomers in the backbone of poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymer structures can affect properties such as the binding of the composition to the substrate, and therefore the type of substrate to which the composition can be applied. For example, when poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymers contain a high content of vinyl acetate (25% or more), the composition is preferably applied to substrates with lower surface energy, such as polymeric films, which require a "stickier" composition. On the other hand, when poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymers contain a lower content of vinyl acetate (24% or less), the composition is preferably applied to substrates with higher surface energy, including porous or semi-porous substrates, such as paper-based substrates, including paper, card, cardboard, and carton board, which require a less "sticky" composition.

[0064] Preferably, the hot melt adhesive comprises 20 to 80%, for example 30 to 70%, of the composition of the present invention.

[0065] The color-forming compound is mixed into the hot melt adhesive of the composition, thereby distributing, dispersing, suspending or incorporating it homogeneously throughout the hot melt adhesive to form the composition of the first, second or third aspect of the present invention. The color-forming compound is introduced into the hot melt adhesive in solid particulate form. By "color-forming compound" is meant any suitable compound that forms color upon exposure to radiation. By "color" is meant the colors, shades, shades and hues of the visible light color spectrum, i.e., red, orange, yellow, blue, green and violet, as well as black, brown, green-blue, purple, pink, cyan, magenta, white and mixtures of all thereof. It is understood that all primary, secondary, tertiary, quaternary and quinary colors are included, i.e., the color formed by the color-forming compound may be a primary, secondary, tertiary, quaternary or quinary color. In the context of the present invention, terms may also be used to describe different shades of each of the colors of the visible light color spectrum in addition to black, brown, green-blue, purple, pink, cyan, white and magenta. In the context of the present invention, when the composition has a color, it is understood that the color formed upon application of radiation to the composition of the present invention is different from or has a stronger density than the color that the composition of the present invention may have upon formulation, storage, or application to or incorporation into a substrate or multi-layer substrate structure prior to application of radiation thereto. The color formed upon application of radiation to the composition of the present invention is different from or has a stronger density than the color that those portions(s) of the composition may have without radiation being applied to them. In the context of the present invention, when the composition has a color prior to application of radiation, following application of the composition of the present invention to a substrate or multi-layer substrate structure, or following its use in forming a multi-layer substrate structure, the color-forming compound forms a contrasting color upon controlled exposure of a particular region of the composition, and thus the color-forming compound, to radiation from a laser light source(s). By "contrasting color" it is meant that the color formed by the color-forming compound of the composition is separate and easily distinguishable from the background of the composition, i.e., the portion(s) of the composition that is not exposed to radiation, as well as any substrate that is visible through the portion(s) of the composition that is not exposed to radiation.The effective degree of color formation will depend on the density of the color formed compared to the surrounding areas of the composition that have not been exposed to radiation, as well as any substrate visible through the unexposed composition.

[0066] The color-forming compound is an image-forming compound that is particularly suitable for forming an image that displays variable information. By "image-forming compound" is meant that following application of the composition of the present invention to a substrate or multilayer substrate structure, or following its use in forming a multilayer substrate structure, the color-forming compound forms a color and a distinguishable contrasting image on and / or within the substrate or multilayer substrate structure upon controlled exposure of the composition, and thus the color-forming compound, to radiation in specific areas. The image is human and / or machine readable. By "contrasting image" is meant that the image formed by the color-forming compound of the composition is separate and easily distinguishable from the background of the composition, i.e., the portion(s) of the composition that are not exposed to radiation, as well as any substrate visible through the portion(s) of the composition that are not exposed to radiation. The degree of effective formation of the color or image depends on the density of the color or image formed compared to the surrounding areas of the composition that are not exposed to radiation, as well as any substrate visible through the unexposed composition. In the context of the present invention, it is understood that if the composition has a color prior to the application of radiation, the color of the image formed upon application of radiation to the composition of the present invention will be different from, or of greater density than, the color that the composition of the present invention may have upon formulation, storage, or application to or incorporation into a substrate or multilayer substrate structure prior to the application of radiation thereto. The color of the image formed upon application of radiation to the composition of the present invention will be different from, or of greater density than, the color that those portions or portions of the composition to which radiation is not applied may have, thereby forming a contrasting image.

[0067] The composition before the application of radiation, and therefore the background of the composition, may have any color. Alternatively, the composition before the application of radiation, and therefore the background of the composition, may be colorless.

[0068] The composition prior to the application of radiation, and therefore the background of the composition, may be transparent or opaque.

[0069] In the context of the present invention, it is understood that the color-forming compound preferably does not form a color until a specific controlled application of radiation to the composition. In some cases, the color-forming compound may display some color ("background") before the application of radiation to the composition. This may be as a result of the temperature reached during processing, fabrication, or application of the composition to a substrate or multi-layer substrate structure. However, even in this case, the desired color and / or image of the present invention may still be formed by subsequent application of radiation to the composition, since the application of radiation causes the color-forming compound to display a color of stronger density than the "background" color formed, so that an effective contrasting color and / or image is still formed. Preferably, the color-forming compound does not display a color in the portion(s) of the composition to which radiation is not applied, prior to the application of radiation to the composition. Preferably, the color-forming compound displays a color only in the portion(s) of the composition to which radiation is applied, i.e., the portion(s) of the composition exposed to radiation.

[0070] It is understood that the color-forming compounds are selected based on the color(s) that the compound can achieve and the desired color(s) of the image that is formed.

[0071] The color forming compound may be selected from an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, and a leuco dye. It is understood that more than one color forming compound may be present in the composition. Preferably, the color forming compound is an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof.

[0072] Polyvalent metal oxyanions The color forming compound may be an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof. The hydrate may be of an oxyanion of a polyvalent metal or a corresponding oxyacid of a polyvalent metal. The oxyanion of a polyvalent metal or an oxyacid of a polyvalent metal may also be anhydrous. The oxyanion of a polyvalent metal or an oxyacid or hydrate thereof may be any suitable oxyanion of a polyvalent metal present in combination with a cationic counterpart (anionic component). The use of oxyanions of polyvalent metals in compositions is disclosed in U.S. Pat. No. 7,485,403, the contents of which are incorporated herein by reference. The anionic component may be an inorganic metal oxyanion compound, such as molybdate, including di-, tri-, hexa-, hepta-, octa- and deca-molybdate, tungstate, chromate, or similar transition metal compounds of mixed oxidation states and similar transition metal compounds of mixed inorganic metal oxyanions. Preferably, the accompanying cationic component is an alkali metal, such as sodium, or an alkaline earth metal, or ammonium. One example of a preferred hydrate of an oxyanion of a polyvalent metal is sodium molybdate dihydrate. Another example of a preferred hydrate of an oxyanion of a polyvalent metal or its oxyacid is ammonium paratungstate. Preferred oxyanions of polyvalent metals are ammonium salts of inorganic metal oxyanion compounds. Ammonium salts of the oxyanion of molybdenum are particularly preferred as the oxyanion of the polyvalent metal. A particularly preferred oxyanion of a polyvalent metal is ammonium octamolybdate (NH4)4Mo8O 26 or "AOM," a commercially available molybdenum composition having the CAS number 12411-64-2.

[0073] Preferably, the polyvalent metal oxyanion or oxyacid or hydrate thereof is a polyvalent metal oxyanion or hydrate of a polyvalent metal oxyanion. More preferably, the polyvalent metal oxyanion or oxyacid or hydrate thereof is sodium molybdate dihydrate or an ammonium salt of a polyvalent metal oxyanion, such as an ammonium salt of a molybdenum oxyanion. More preferably, the polyvalent metal oxyanion or oxyacid or hydrate thereof is sodium molybdate dihydrate or ammonium octamolybdate (AOM). More preferably, the polyvalent metal oxyanion or oxyacid or hydrate thereof is ammonium octamolybdate (AOM).

[0074] In the context of the present invention, when the oxyanion of a polyvalent metal or its oxyacid or hydrate is an ammonium salt of the oxyanion of a polyvalent metal, for example, an ammonium salt of the oxyanion of molybdenum, such as ammonium octamolybdate (AOM), the colors and / or images formed when the oxyanion of a polyvalent metal or its oxyacid or hydrate is utilized as a color forming compound are typically black in color or shade and include a gray scale depending on the density of the black color formed by the radiation. The colors and / or images are effective and visible to humans and / or machines. In such cases, besides being visually distinguishable, the effective formation of the color or image may be indicated by a measurement of the absolute optical density (ODB) black value. This measures the density of the black color of the image. In the context of the ODB value, the higher the value, the darker the black color formed. The ΔODB value (absolute ODB value - background ODB) may also be measured to indicate the effective formation of the color or image. The "background ODB" is a measure of the composition of the substrate, i.e., the portion(s) of the composition that is not exposed to radiation, as well as the background of any substrate visible through it. Thus, the ΔODB value is a measure of the difference in optical density between the image and the non-imaged portion(s) of the composition. For the present invention, a ΔODB value of 0.5 or more, preferably 0.7 or more, such as 0.8 or more, and most preferably 1.0 or more is desirable. Such values ​​indicate the formation of high contrast images by the compositions of the present invention upon exposure to radiation. It quantifies the optical density on a black scale from low to high values, and ODB measurements can be made using a standard instrument densitometer and an X-Rite eXact or SpectroEye spectrophotometer.

[0075] In the context of the present invention, when the polyvalent metal oxyanion or its oxyacid or hydrate is sodium molybdate dihydrate, the colors and / or images formed when the polyvalent metal oxyanion or its oxyacid or hydrate is utilized as a color-forming compound are typically lighter in color or shade. The colors and / or images are human and / or machine visible. Without being bound by theory, the inventors believe that when sodium molybdate dihydrate is utilized, upon application of radiation, preferably from a laser light source(s), the sodium molybdate dihydrate dehydrates (thermally decomposes) to a dehydrated form. Without being bound by theory, the inventors believe that the degassing or outgassing of water vapor ("bubbles") from the sodium molybdate dihydrate creates microscopic depressions or bubbles, resulting in a change in refractive index, such that the composition displays a white color following application of radiation.

[0076] For sodium molybdate dihydrate, the effective formation of a color and / or image, other than being visually distinguishable by humans and / or machines, may be indicated by a measurement of opacity value. This may be used as a measure of color and / or image density. As used herein, opacity is a measure of the impenetrability of a composition to light, in this case visible light. Opacity is expressed as a percentage from transparent (0%) to opaque (100%). The percentage is a measure of the amount of light that does not pass through the composition, i.e., at 0% opacity, the composition is completely transparent since 0% of the light does not pass through the composition, and at 100% opacity, the composition is completely opaque since 100% of the light does not pass through the composition. In the context of the present invention, the opacity values ​​of both the area of ​​the composition to which radiation has been applied (image) and the area of ​​the composition to which radiation has not been applied (background) can be measured to indicate the effective formation of a distinguishable human and / or machine readable image. In the context of the present invention, it will be recognized by those skilled in the art that the opacity of the image is greater than the opacity of the background, resulting in the formation of a distinguishable human and / or machine readable image. The greater the difference in opacity value between the image and the background, the clearer and more distinguishable the image is.

[0077] When the oxyanion of a polyvalent metal or its oxyacid or hydrate is sodium molybdate dihydrate, the background of the composition, i.e. the portion(s) of the composition to which radiation is not applied, may have an opacity of 20% or less, such as 15% or less, preferably 10% or less, or even 5% or less. Furthermore, the area of ​​the composition to which radiation is applied, and the image formed thereon, may have an opacity of 40% or more, such as 45% or more, preferably 50% or more, or even 60% or more, such as 70% or more. It is understood that the higher the opacity value of the image, the clearer and more distinguishable the image formed is. Thus, a high opacity value indicates effective image formation.

[0078] In the context of the present invention, the opacity measurement is performed using the opacity function of the Techkon SpectroDens spectrophotometer according to ASTM standard ASTM D589-97, where the imaged (image) and non-imaged (background) areas of the composition of the substrate or multi-layer substrate structure are measured against black and white standards, respectively. First, the opacity function of the Techkon SpectroDens spectrophotometer is selected, then the opacity of the composition of the substrate is measured against a black Leneta chart, then the opacity of the composition of the substrate or multi-layer substrate structure is measured against a white background, such as a minimum of 50 sheets of white paper, and the resulting opacity measurement is displayed by the Techkon SpectroDens spectrometer.

[0079] The oxyanion of the polyvalent metal or its oxyacid or hydrate is introduced and present in the composition in the form of solid fine particles. The oxyanion of the polyvalent metal or its oxyacid or hydrate has a D of 0.1 to 20 μm, for example 0.5 to 15 μm, or 0.5 to 10 μm, preferably 1 to 3 μm. 50 It may contain particles having a particle size distribution.

[0080] As used herein, the term "D 50"Particle size distribution" refers to the median particle size of particles of the polyvalent metal oxyanion or its oxyacid or hydrate, i.e., the particle size of exactly 50% of the particle population by number.

[0081] It is recognized by those skilled in the art that the particle size distribution measurement is performed prior to the incorporation of the oxyanion of the polyvalent metal or its hydrate or oxyacid into the hot melt adhesive during the formation of the composition. The particle size distribution measurement defined herein is measured by a conventional Malvern Mastersizer® 3000 particle size analyzer from Malvern Instruments according to ISO 13320:2009.

[0082] The particles of the polyvalent metal oxyanions of the present invention are 2 / kg or more, for example 1200m 2 / kg or more, or 1500m 2 / kg or more, preferably 2000m 2 / kg or more, for example 2500m 2 / kg or more, for example 3000m 2 / kg or more, or 3700m 2 / kg, more preferably 4000m 2 / kg or more.

[0083] Surface area is measured using a Malvern Mastersizer according to ISO standard 13320:2009, which calculates surface area from particle size distribution data.

[0084] The polyvalent metal oxyanion or its oxyacid or hydrate may have a decomposition temperature of 80-700°C, or 80-500°C, such as 100-500°C, for example 150-400°C, or even 200-300°C. The decomposition temperature is the temperature at which the polyvalent metal oxyanion or its oxyacid or hydrate forms color. The decomposition temperature of the polyvalent metal oxyanion or its oxyacid or hydrate is the temperature at which the compound chemically decomposes. In some literature, this may also be known as the melting temperature. For sodium molybdate dihydrate, this is considered to be the temperature at which water evaporates from it.

[0085] The decomposition temperature of ammonium octamolybdate (AOM) is 275°C. The decomposition temperature of sodium molybdate dihydrate is 100°C.

[0086] The decomposition temperature of the oxyanion of the polyvalent metal or its oxyacid or hydrate may be measured using differential scanning calorimetry (DSC) or thermogravimetric analysis (TGA). Preferably, the decomposition temperature is measured using DSC, a technique well known to those skilled in the art.

[0087] DSC is a technique well known to those skilled in the art and is a thermoanalytical technique in which the difference in the amount of heat energy required to change the temperature of a polyvalent metal oxyanion sample and a reference is measured as a function of temperature. The aim is for both the polyvalent metal oxyanion sample and the reference to be maintained at the same temperature so that DSC can determine the endothermic transition, or decomposition temperature, at which the polyvalent metal oxyanion decomposes and becomes fluid. The underlying principle of DSC is that if the polyvalent metal oxyanion sample undergoes a physical transformation, more heat energy will be required to keep both isothermal in order for the sample to flow compared to the reference. By measuring the difference in heat flow between the sample and the reference, DSC can determine the amount of heat absorbed during the endothermic transition.

[0088] The polyvalent metal oxyanion or oxyacid or hydrate thereof may be present in the composition according to the invention in any suitable amount, preferably the polyvalent metal oxyanion or oxyacid or hydrate thereof is present in an amount of from 5 to 80% of the composition, for example from 10 to 70%, from 20 to 60% or from 25 to 55%.

[0089] Leuco Dyes The color-forming compound may be a leuco dye. Leuco dyes are well known to those skilled in the art as compounds capable of forming color. Examples of suitable leuco dyes are included in WO 2015 / 015200 and WO 2013 / 068729, the contents of which are incorporated herein by reference. Suitable leuco dyes include, but are not limited to, any commercially available or chemically synthesized leuco dyes, including, but not limited to, commercially available thermochromic and halochromic leuco dyes. Examples of suitable leuco dyes include, but are not limited to, spirooxazines, naphthopyrans, phthalides, fluorans, triarylmethanes, benzoxazines, quinazolines, spiropyrans, quinones, tetrazolium salts, thiazines, phenazines and oxazines, some of which are disclosed in WO 2006 / 108745, the contents of which are incorporated herein by reference.

[0090] The leuco dye may be selected from: 3-di-n-butylamino-6-methyl-7-phenylaminofluoran (ODB-2:Wincon-2); 3-(N-ethyl-Np-tolylamino)-6-methyl-7-anilinofluoran or 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[5-isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (CAS No. 59129-79-2) (ETAC); 6-(dimethylamino)-3,3-bis[4-(dimethylamino)phenyl]phthalide (Blue I2R - Crystal Violet Lactone); and 3,3'-bis(1-n-octyl-2-methylindol-3-yl)phthalide (Red I6B).

[0091] Suitable suppliers of leuco dyes include, but are not limited to, Yamada Chemical Company Limited (Yamada), Chameleon Speciality Chemicals Limited, and Connect Chemicals.

[0092] Suitable leuco dyes from Yamada include, but are not limited to, Green 300 (Fluoran); spiro[11H-[1]benzopyrano[2,3-g]quinolone-11,1'(3'H)-isobenzofuran]-3'-one, 1-ethyl-8-[ethyl(4-methylphenyl)amino]-1,2-dihydro-2,2,4-trimethyl (H-1046, Fluoran) (CAS No. 140895-67-6); CVL (Phthalide); BLUE 203 (Pyridine Blue); BLUE 220 (Pyridine Blue); BLMB (Phenothiazine); Red 500 (Fluoran); Red 520 (Fluoran); Red 550 (Fluoran); S-205 (Fluoran); Black 305 (Fluoran); Black 400 (Fluoran); Black 100 (Fluoran); and NIR Black 78 (Divinylphthalide).

[0093] The leuco dye may further be selected from the following: 2-anilino-3-diethylamino-6-methylethyl fluoran (chameleon black 1), 2-anilino-6-dibutylamino-3-methylethyl fluoran (chameleon black 2), 6-(dimethylamino)-3,3-bis[4-(dimethylamino)phenyl]phthalide (chameleon blue 3), 4,4'-[(9-butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline] (chameleon blue 4), 3,3'-bis(1-n-octyl-2-methylindol-3-yl)phthalide (chameleon red 5), 6'-(diethylamino)-3-oxo-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-2'-carboxylic acid ethyl ester (chameleon orange 6). , 7-[4-(diethylamino)-2-ethoxyphenyl]-7-(2-methyl-1-octyl-1H-indol-3-yl)furo[3,4-b]pyridin-5(7H)-one (Chameleon Blue 8), 2'-(dibenzylamino)-6'-(diethylamino)fluoran (Chameleon Green 9), N,N-dimethyl-4-[2-[2-(octyloxy)phenyl]-6-phenyl-4- pyridinyl]-benzenamine (Chameleon Yellow 10), 6'-(diethylamino)-2'-[(dimethylphenyl)amino]-3'-methylspiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (Chameleon Black 15), 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-xanthene]-3-one (CAS No. 89331-94-2) (ODB-2 / Wincon-2), 6'-(diethylamino)-3'-methyl-2'-(phenylamino)spiro[2-benzofuran-3,9'-xanthene]-1-one (ODB-1 / Wincon-1) (CAS No. 29512-49-0), 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[5-isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (CAS No. 59129-79-2), 6-(dimethylamino)-3,3-bis-[4-(dimethylamino)phenyl]phthalide (Blue 3-CVL, CAS No.1522-42-7), 4,4'-[(9-butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline] (Blue-4, CAS No. 67707-04-4), 3,3'-bis(1-n-octyl-2-methylindol-3-yl)phthalide (Red-5, CAS No. 50292-95-0), 6'-(diethylamino)-3-oxo-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-2'-carboxylic acid ethyl ester (Orange-6, CAS No. 154306-60-2), 7-[4-(diethylamino)-2-ethoxyphenyl]-7-(2-methyl-1-octyl-1H-indol-3-yl)furo[3,4-b]pyridin-5(7H)-one (Blue-8, CAS No. 87563-89-1), 2'-(dibenzylamino)-6'-(diethylamino)fluoran (Green-9, CAS No. 34372-72-0), N,N-dimethyl-4-[2-[2-(octyloxy)phenyl]-6-phenyl-4-pyridinyl]-benzenamine (Yellow-10, CAS No. 144190-25-0), 6'-(diethylamino)-2'-[(dimethylphenyl)amino]-3'-methylspiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (Black-15, CAS No.36431-22-8), 2-anilino-3-diethylamino-6-methylethyl fluoran, 2-anilino-6-dibutylamino-3-methylethyl fluoran, 6-(dimethylamino)-3,3-bis[4-(dimethylamino)phenyl]phthalide, 4,4'-[(9-butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline], 3,3'-bis(1-n-octyl-2-methylindol-3-yl)phthalide, 6'-(diethylamino)-3-oxo-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-2'-carboxylic acid ethyl ester, 7-[4-(diethylamino) -2-ethoxyphenyl]-7-(2-methyl-1-octyl-1H-indol-3-yl)furo[3,4-b]pyridin-5(7H)-one, 2'-(dibenzylamino)-6'-(diethylamino)fluoran, N,N-dimethyl-4-[2-[2-(octyloxy)phenyl]-6-phenyl-4-pyridinyl]-benzenamine, and 6'-(diethylamino)-2'-[(dimethylphenyl)amino]-3'-methylspiro[isobenzofuran-1(3H),9'-[9H]xanthen]-3-one, 4,4'-[(9-butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline] (CAS No. 67707-04-4), 6'-(diethylamino)-3-oxospiro[isobenzofuran-1(3H),9'-(9H)xanthene]-2'carboxylic acid ethyl ester (CAS No. 154306-60-2), and 2'-(dibenzylamino)-6'-(diethylamino)fluoran (CAS No. 34372-72-0).

[0094] Preferably, the leuco dye is selected from 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-xanthene]-3-one (ODB-2, CAS No. 89331-94-2), 6'-(diethylamino)-3'-methyl-2'-(phenylamino)spiro[2-benzofuran-3,9'-xanthene]-1-one (CAS No. 29512-49-0), and 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[5 isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (ETAC) (CAS No. 59129-79-2). Preferably, the leuco dye is 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-xanthene]-3-one (ODB-2, CAS No. 89331-94-2) or 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[5-isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (ETAC) (CAS No. 59129-79-2).

[0095] The leuco dye may have a melting temperature of 80-220°C, for example 100-220°C, or even 160-210°C. In the context of a leuco dye, this is the temperature at which the leuco dye forms color. As discussed below, the leuco dye forms color when the accompanying thermal acid generator is also in the same liquid state (discussed in more detail below). In the context of a leuco dye, the melting temperature refers to the temperature at which the leuco dye transitions from a solid particulate form (solid state) to a liquid state (i.e., melt).

[0096] The melting temperature of the leuco dye may be measured using a melting point measuring device using a thermometer or differential scanning calorimetry (DSC). Preferably, the melting temperature is measured using DSC, a technique well known to those skilled in the art.

[0097] DSC is a technique well known to those skilled in the art and is a thermal analysis technique in which the difference in the amount of heat energy required to change the temperature of a leuco dye sample and a reference is measured as a function of temperature. The aim is for both the leuco dye sample and the reference to maintain the same temperature so that DSC can determine the endothermic transition at which the leuco dye melts, i.e. the melting temperature. The underlying principle of DSC is that if the leuco dye sample undergoes a physical transformation, more heat energy will be required to keep both isothermal for the sample to flow compared to the reference. By measuring the difference in heat flow between the sample and the reference, DSC can determine the amount of heat absorbed during the endothermic transition.

[0098] The melting temperature of 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-xanthene]-3-one (ODB-2, CAS No. 89331-94-2) is 183°C. The melting temperature of 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[5-isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (ETAC) (CAS No. 59129-79-2) is 206°C.

[0099] In the context of the present invention, when a leuco dye is utilized as the color forming compound of the composition, the image formed may be any suitable color. For example, the image may be formed in a color selected from red, blue, green, orange, yellow and black or shades thereof. When the color is black or a shade thereof, this includes a gray scale depending on the density of the black color formed by the radiation. It is understood that the particular leuco dye is selected according to the color required for the image of the substrate.

[0100] When a leuco dye is utilized as the color forming compound of the composition, the effective formation of the color and / or image may be indicated by the measurement of the optical density value. The color and / or image is visible to humans and / or machines. For black formation, this is the absolute optical density black (ODB) value measured as discussed above for the oxyanion of a polyvalent metal or its oxyacid or hydrate. For red formation, the effective image formation is measured by the absolute optical density magenta (ODM) value, which measures the red density of the image. For blue formation, the effective image formation is measured by the absolute optical density cyan (ODC) value, which measures the blue density of the image. For yellow formation, this is measured by the absolute optical density yellow (ODY) value, which measures the yellow density of the image. In the context of ODM, ODC and ODY values, the higher the value, the more intense the red, blue or yellow color formed, respectively. ΔODB, ΔODM, ΔODC and ΔODY values ​​may also be measured to indicate effective formation of color or image in the same manner as detailed above for ΔODB of oxyanions of polyvalent metals or their oxyacids or hydrates. For the present invention, ΔODB, ΔODM, ΔODC or ΔODY values ​​of 0.5 or more, preferably 0.7 or more, such as 0.8 or more, and most preferably 1.0 or more are desired. Such values ​​indicate formation of high contrast images by the compositions of the present invention upon exposure to radiation. ODB, ODM, ODC and ODY values ​​can be measured using a standard instrument densitometer and an X-Rite eXact or SpectroEye spectrophotometer.

[0101] With respect to the composition according to the first, second or third aspect of the present invention, when the color forming compound is a leuco dye, the leuco dye is accompanied in the composition by a thermal acid generator (TAG). Thus, in such a case, the hot melt adhesive of the composition of the present invention, when the color forming compound is a leuco dye, further has a thermal acid generator mixed therein and thus distributed throughout.

[0102] It is recognized by those skilled in the art that the thermal acid generator and the leuco dye interact and react with each other to achieve color formation. Without being bound by theory, the inventors believe that color formation is facilitated when the leuco dye and the thermal acid generator are melted from a solid particulate form (solid state) into the same liquid state. In the context of the present invention, without being bound by theory, the inventors believe that such interaction of the thermal acid generator with the leuco dye occurs upon application of radiation to the composition when both the leuco dye and the thermal acid generator are in the same liquid state.

[0103] Suitable thermal acid generators include any suitable commercially available or chemically synthesized thermal acid generator. Suitable thermal acid generators include, but are not limited to, 4-hydroxyphenyl-4'-isopropoxyphenyl sulfone (Chameleon Developer-1); N-(p-toluenesulfonyl)-N'-(3-(p-toluenesulfonyloxy)phenyl)urea (Pergafast 201); thermal acid generators based on 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) and amine salts of borobenzilate and tri-n-butylammonium borodisalicylate, such as tri-n-butylammonium-4,4'-dioxo-4H,4'H-2,2'-spirobi[benzo[d][1,3,2]dioxaborinine]-2-uido or N,N-dibutylbutan-1-aminium bis[2-(hydroxykO)benzoato(2-)-kO]borate(1-), as well as 4-hydroxy-4'-isopropoxydiphenylsulfone, (2,4-dihydroxyphenyl)phenylmethanone, 3-(3-tosylureido)phenyl-4-methylbenzenesulfonate, 3,4,5-trihydroxybenzoic acid propyl and 4,4'-methanediyldiphenol.

[0104] Preferably, the thermal acid generator is selected from 1,1,1-tris(4-hydroxyphenyl)ethane (THPE), tri-n-butylammonium-4,4'-dioxo-4H,4'H-2,2'-spirobi[benzo[d][1,3,2]dioxaborinine]-2-uido, N,N-dibutylbutan-1-aminium bis[2-(hydroxy-kO)benzoato(2-)-kO]borate(1-), 4-hydroxy-4'-isopropoxydiphenylsulfone, (2,4-dihydroxyphenyl)phenylmethanone, 3-(3-tosylureido)phenyl-4-methylbenzenesulfonate, 3,4,5-trihydroxybenzoic acid propyl, and 4,4'-methanediyldiphenol. More preferably, the thermal acid generator is selected from 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) and N,N-dibutylbutan-1-aminium bis[2-(hydroxy-kO)benzoato(2-)-kO]borate(1-). More preferably, the thermal acid generator is 1,1,1-tris(4-hydroxyphenyl)ethane (THPE).

[0105] The thermal acid generator may have a melting temperature of 100-270° C., for example, 110-250° C. In the context of thermal acid generators, the melting temperature is the temperature at which the thermal acid generator transitions from a solid particulate form (solid state) to a liquid state (i.e., melt). As discussed in more detail herein, this is the temperature at which the thermal acid generator has the ability to enable the leuco dye to form color when the accompanying leuco dye is also in the same liquid state.

[0106] The melting temperature of the thermal acid generator may be measured using a melting point apparatus equipped with a thermometer, or by differential scanning calorimetry (DSC). Preferably, the melting temperature is measured using DSC, a technique well known to those skilled in the art.

[0107] DSC is a technique well known to those skilled in the art and is a thermal analysis technique in which the difference in the amount of heat energy required to change the temperature of a thermal acid generator sample and a reference is measured as a function of temperature. The aim is for both the thermal acid generator sample and the reference to maintain the same temperature so that DSC can determine the endothermic transition at which the thermal acid generator melts, i.e., the melting temperature. The underlying principle of DSC is that if the thermal acid generator sample undergoes a physical transformation, more heat energy will be required to keep both isothermal for the sample to flow compared to the reference. By measuring the difference in heat flow between the sample and the reference, DSC can determine the amount of heat absorbed during the endothermic transition.

[0108] The melting temperature of 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) is 244-248°C. The melting temperature of N,N-dibutylbutan-1-aminium bis[2-(hydroxykO)benzoato(2-)-kO]borate(1-) is 139°C.

[0109] It is understood that the thermal acid generator is also introduced into the hot melt adhesive in solid particulate form during formation of the composition.

[0110] The leuco dye may be present in the composition according to the first, second or third aspect of the invention in any suitable amount. Preferably the leuco dye is present in an amount of from 5 to 80% of the composition, for example from 10 to 40%.

[0111] When the colour-forming compound is a leuco dye, the thermal acid generator may be present in any suitable amount in the composition according to the first, second or third aspect of the invention. Preferably, when the colour-forming compound of the composition according to the first, second or third aspect of the invention is a leuco dye, the thermal acid generator may be present in an amount of from 10 to 80%, for example from 15 to 50%, of the composition.

[0112] It will be appreciated by those skilled in the art that during the formulation of the composition according to the first, second or third aspect of the invention, i.e. during the incorporation of the color-forming compound into the hot melt adhesive, or during the application of the composition to a substrate or multi-layer substrate structure and / or during its use in forming a multi-layer substrate structure, the hot melt adhesive is required to melt so that it can flow. This is achieved by heating the hot melt adhesive, and thus the composition, to above, and preferably above, the melting temperature of the hot melt adhesive. As discussed above, it will be appreciated by those skilled in the art that this can encompass a melting temperature range. In order to be able to form color and / or images in the composition by application of radiation after these formulation or application steps, it will be appreciated by those skilled in the art that the melting or decomposition temperature of the color-forming compound, including the melting temperature of the thermal acid generator, if present, will not be reached. Therefore, in order to be able to form color and / or images in the composition by application of radiation after these formulation or application steps, during heating in either the formulation or application steps, a suitable selection of the hot melt adhesive and the color-forming compound is required. Such a selection will depend on the relationship of the melting temperature of the hot melt adhesive and the melting or decomposition temperature of the color forming compound (including the melting temperature of the thermal acid generator, if present).

[0113] With respect to the composition according to the first, second or third aspect of the present invention, the melting temperature of the hot melt adhesive is lower than the temperature at which the color forming compound forms color, i.e. the melting temperature of the hot melt adhesive is lower than the melting or decomposition temperature of the selected color forming compound and, if present, the melting temperature of the thermal acid generator.

[0114] When a polyvalent metal oxyanion or its oxyacid or hydrate is utilized as a color forming compound of the composition according to the invention, the decomposition temperature of the polyvalent metal oxyanion or its oxyacid or hydrate is higher than the melting temperature of the hot melt adhesive. Thus, the hot melt adhesive or composition may be heated to a temperature equal to or higher than, and preferably higher than, the melting temperature of the hot melt adhesive so that the hot melt adhesive melts and becomes suitable for application to a substrate, a multi-layer substrate structure or a substrate of a multi-layer structure. However, this temperature is lower than the decomposition temperature of the polyvalent metal oxyanion or its oxyacid or hydrate. Thus, color and / or image formation can be subsequently controlled and achieved by applying radiation to the composition when required.

[0115] With regard to the composition of the third aspect of the present invention, when the color forming compound is ammonium molybdate (AOM) or a defined leuco dye, it is understood that the decomposition or melting temperature of these color forming compounds is higher than the melting temperature of the hot melt adhesive, as detailed herein, from 50 to 200°C, or from 50 or 160°C, including from 70 to 150°C.

[0116] When a leuco dye is utilized as a color-forming compound of the composition according to the first, second or third aspect of the present invention with a thermal acid generator, the melting temperature of both the leuco dye and the thermal acid generator is higher than the melting temperature of the hot melt adhesive of the composition. This is to ensure that both the leuco dye and the thermal acid generator remain in solid particulate form when the melting temperature of the hot melt adhesive is reached. This is to avoid color formation caused by the interaction between the leuco dye and the thermal acid generator, which would interfere with the formation of color and / or image upon subsequent application of radiation. Without being bound by theory, color formation is facilitated when the leuco dye and the thermal acid generator are melted from a solid particulate form (solid state) to the same liquid state, i.e., when one or both of the melting temperatures of the leuco dye and the thermal acid generator are reached, and the leuco dye and the thermal acid generator can intimately interact and react in the same liquid phase. Thus, the hot melt adhesive or composition may be heated to a temperature at or above, and preferably above, the melting temperature of the hot melt adhesive, such that the hot melt adhesive becomes melted and suitable for application to a substrate, multi-layer substrate structure, or substrate of a multi-layer structure. Color and / or image formation can then be controlled and achieved by application of radiation to the composition, if required.

[0117] It is therefore understood that the hot melt adhesive, color forming compound, and thermal acid generator, if present, are selected according to their respective melting or decomposition temperatures and the relationship therebetween, as appropriate. Color formation which would interfere with the formation of color and / or images upon subsequent application of radiation is thus avoided during the fabrication, processing and application of the compositions of the present invention to substrates, multilayer substrate structures, or in the formation of laminated substrate structures, prior to the application of controlled radiation which facilitates the formation of the desired color or image.

[0118] Furthermore, it will be appreciated by those skilled in the art that when a composition according to the first, second or third aspects of the present invention comprises more than one color-forming compound, both of the color-forming compounds must conform to the relationships set forth above.

[0119] It will be appreciated by those skilled in the art that the ranges of melting or decomposition temperatures of the color-forming compounds and the melting temperatures of the thermal acid generators detailed herein overlap with those of the hot-melt adhesives detailed herein, but that the hot-melt adhesives, color-forming compounds, and, if present, the thermal acid generators of the compositions of the present invention are selected to maintain the relationships set forth above.

[0120] It will be appreciated by those skilled in the art that the present invention encompasses compositions in which the hot melt adhesive melts during fabrication, processing and application, as well as compositions in which the hot melt adhesive is in a solid state (when cooled to room temperature) during storage or after application of the composition to a substrate or multi-layer substrate structure.

[0121] The hot melt adhesive of the composition according to the first or third aspect of the present invention may further have an infrared absorbing compound mixed therein. Preferably, the hot melt adhesive of the composition according to the first or third aspect of the present invention has an infrared absorbing compound mixed therein.

[0122] The hot melt adhesive of the composition according to the second aspect of the present invention further has an infrared absorbing compound mixed therein.

[0123] With respect to the color-forming compound, the infrared absorbing compound is distributed, dispersed, suspended, or incorporated homogeneously throughout the hot melt adhesive of the composition. There may be multiple infrared absorbing compounds. It is understood that an infrared absorbing compound is typically included when infrared (IR) radiation, including near infrared (NIR) radiation, is to be utilized for color and / or image formation. The infrared absorbing compound is capable of enhancing the absorption of IR radiation and thus enhancing the color and / or image formed. Examples of suitable infrared absorbing compounds include, but are not limited to, inorganic copper salts such as copper(II) hydroxyl phosphate (CHP); organic NIR dyes and pigments such as N,N,N',N'-tetrakis(4-dibutylaminophenyl)-p-benzoquinone bis(iminium hexafluoro-antimonate); reduced indium tin oxide, reduced zinc oxide, reduced tungsten oxide, compounds of the formula MxWyOz, where M is H, He, an alkali metal, an alkaline earth metal, a rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, at least one element selected from the group consisting of Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi and I, W is tungsten and O is oxygen, satisfying 0.001≦x / y≦1; and 2.2≦z / y≦3.0; non-stoichiometric reduced or doped inorganic compounds such as reduced doped tungsten oxide, reduced antimony tin oxide, or doped metal oxides such as aluminum doped zinc oxide (AZO) and fluorine doped tin oxide (FTO); conductive polymers such as polystyrene sulfonate (PEDOT); and combinations thereof.

[0124] Preferably, the infrared absorbing compound is an inorganic copper salt, such as copper(II) hydroxylphosphate (CHP); reduced indium tin oxide, reduced zinc oxide, reduced tungsten oxide, a compound of the formula MxWyOz, where M is at least one element selected from the group consisting of H, He, an alkali metal, an alkaline earth metal, a rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I, W is tungsten, and O is oxygen, and satisfying 0.001≦x / y≦1; and 2.2≦z / y≦3.0. In one embodiment, the inorganic compound is selected from the group consisting of non-stoichiometric reduced or doped inorganic compounds, such as reduced and doped tungsten oxides, including inorganic compounds of the formula:

[0125] When present, the infrared absorbing compound may be present in any suitable amount in a composition according to the invention. Preferably, the infrared absorbing compound comprises from 0.1 to 33% of the composition, for example from 0.5 to 30% of the composition.

[0126] The infrared absorbing compound is introduced into the composition in solid particulate form. When present in the composition, the infrared absorbing compound is in solid particulate form.

[0127] It will be appreciated by those skilled in the art that when an infrared absorbing compound is present, the radiation used to produce color or images in the composition is preferably IR radiation.

[0128] The composition of the present invention does not contain solvents or water. No water or solvents are present in either the hot melt adhesive or the composition of the present invention.

[0129] The compositions of the present invention are radiation-responsive compositions, laser-responsive compositions, i.e., capable of forming colors and / or images upon application of radiation to the composition, preferably from a laser source(s).

[0130] The composition according to the present invention may be applied to any suitable substrate, it being understood that the contents of the composition may vary depending on the substrate to which the composition is applied.

[0131] Thus, according to a fourth aspect of the invention, there is provided a substrate comprising a composition according to the first, second or third aspect of the invention, having the composition applied thereon.

[0132] With respect to the fourth aspect of the invention, the composition may have any of the features described as preferred or optional in relation to any other aspect of the invention.

[0133] Examples of suitable substrates to which the composition may be applied include, but are not limited to, polymers and recycled polymeric materials, such as polyhydroxyalkanoates (PHAs), poly(glycolic acid) (PGA), polyethylene terephthalate (PET), poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymers, polyethylene (PE), low density polyethylene (LDPE), high density polyethylene (HDPE), polystyrene (PS), polypropylene (PP), oriented polypropylene (OPP), biaxially oriented polypropylene (BOPP), Cast polypropylene (CPP), polyamides (PA) such as nylon, polyvinyl chloride (PVC), or combinations thereof; cellulose; glass; plastics; metals and metal foils, such as tinplate; textiles; paper-based substrates including paper, cards, cartons, paperboard, carton board, corrugated paper, corrugated card, corrugated carton, corrugated paperboard, cardboard, corrugated carton board, folding carton, and equivalent recycled analogs, or combinations thereof; ceramics; foodstuffs and pharmaceuticals; or combinations thereof, such as polymer-coated or polymer-impregnated paper. Suitable substrates include multi-layer substrates formed from the materials and substrates listed above. Polymers and recycled polymer materials may be in the form of polymer foil or film substrates.

[0134] Preferably, the substrate to which the composition is applied is a recyclable, biodegradable and / or compostable substrate.

[0135] The substrate according to the fourth aspect of the invention may be bonded to an additional substrate using, for example, a hot melt adhesive, such that the composition at the substrate is tacky at room temperature. The additional substrate may be as detailed above for the substrate according to the fourth aspect of the invention. A multi-layer substrate structure may be formed in this way.

[0136] In the context of the present invention, when the thermoplastic polymer, copolymer, oligomer or mixture thereof of the hot melt adhesive is a bioplastic thermoplastic polymer, copolymer, oligomer or mixture thereof, the substrate to which the composition is applied is preferably formed from a bioplastic material. Similarly, when the thermoplastic polymer, copolymer, oligomer or mixture thereof of the hot melt adhesive is a petroleum-based plastic polymer, copolymer, oligomer or mixture thereof, the substrate to which the composition is applied is preferably formed from a petroleum-based plastic material. Bioplastic materials encompassed herein include, but are not limited to: poly(lactic acid) (PLA), polyhydroxyalkanoate (PHA) and poly(glycolic acid) (PGA), as well as poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymer when formed from ethanol derived from sugar cane and / or other natural sources, and polyethylene when formed from sugar cane and / or other natural sources. For the poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymer and polyethylene materials listed herein for substrates, both bioplastic and petroleum-based plastic forms are encompassed.

[0137] The substrate to which the composition is applied may have a thickness of from 12 μm to 5 mm, for example from 12 μm to 500 μm. In particular, when the substrate is a paper-based substrate, the paper-based substrate may have a weight per unit area (gsm) of from 50 to 500 gsm, for example from 60 to 250 gsm, including from 80 to 200 gsm.

[0138] It is understood that the substrate may have a single layer or multiple layers of the composition according to the invention applied thereto. Preferably, only a single layer of the composition is required. This is advantageous over multiple layers of the composition that are necessary to achieve effective color and / or image formation in conventional printing processes.

[0139] The compositions according to the invention are preferably applied directly to the substrate.

[0140] With respect to a substrate according to the present invention, the composition may be applied to all, substantially all or a portion of the surface area of ​​that surface.

[0141] Preferably, the composition is applied to the outer surface of the substrate so that it is exposed, ie, there is no layer, such as a protective layer or other layer, overlying the composition.

[0142] When substrates are utilized in forming the products discussed below, the composition may be present on any surface thereof, internal or external.

[0143] It is understood that the fourth aspect of the present invention includes a substrate having a composition, to which the composition has been applied, where the composition is freshly applied and molten, i.e., before cooling to room temperature. The fourth aspect of the present invention also includes a substrate having a composition, to which the composition has been applied, where the composition is solid at room temperature. The composition may be tacky or non-tacky at room temperature.

[0144] It is understood that for substrates according to the present invention, prior to the application of radiation, the color-forming compounds of the composition applied to the substrate preferably do not display color.

[0145] According to a fifth aspect of the present invention there is provided a multi-layer substrate structure comprising a composition according to the first, second or third aspects of the present invention, having the composition applied thereon and / or incorporated therein.

[0146] With respect to the fifth aspect of the invention, the composition may have any of the features described as preferred or optional with respect to any other aspect of the invention.

[0147] A multi-layer substrate structure may be formed from at least two substrates bonded together with a composition. For such a multi-layer substrate structure, the composition may be utilized to bond the substrates together such that it is between the at least two substrates and is incorporated within the multi-layer substrate structure. Alternatively, the multi-layer substrate structure may be formed from at least two substrates and have the composition according to the present invention applied to their surfaces. The multi-layer structure may further comprise a substrate bonded to the at least two substrates discussed above, it being understood that said further substrate(s) is bonded with the same adhesive, or usually another adhesive, that does not include a color-forming compound mixed therein. Other adhesives are well known to those skilled in the art.

[0148] With respect to the fifth aspect of the invention, each of the substrates of the multi-layer substrate structure may be formed from one of the substrates described above with respect to the third aspect of the invention.

[0149] Typically, the multi-layer substrate structure according to the fifth aspect of the invention is formed from at least two substrates (formed from substrates as described above with respect to the fourth aspect of the invention), with the at least two substrates having the composition according to the invention sandwiched therebetween. It is therefore understood that the composition is utilized to bond the two substrates together. In such cases, it is understood that the composition should still be visible, e.g., typically at least one of the substrates, e.g., polymeric film, is transparent or translucent, so that any color and / or image formed is visible and human and / or machine readable.

[0150] In forming the multi-layer substrate structure of the present invention, the composition is applied to the multi-layer substrate structure or It is understood that the coating may be applied to one of at least two substrates, either a single layer or multiple layers, preferably a single layer, prior to bonding to the other to form a multi-layer substrate structure.

[0151] In forming a multi-layer substrate structure according to the present invention, it is understood that the composition may be applied to all, substantially all or a portion of the surface area of ​​the multi-layer substrate structure, or to a substrate that is to be bonded to another, to form the multi-layer substrate structure.

[0152] Preferably, when the composition is applied to a multi-layer substrate structure, the composition is applied to the outer surface of the multi-layer substrate structure such that it is exposed, i.e., there is no layer, such as a protective layer or other layer, overlying the composition.

[0153] A fifth aspect of the invention is a multi-layer substrate structure having a composition, to which the composition has been applied, where it is understood to include the substrate when the composition has just been applied, molten, i.e., before it has cooled to room temperature. The fifth aspect of the invention also includes a multi-layer substrate structure having a composition, to which the composition has been applied, where the composition has cooled to room temperature and is solid. The composition may be tacky or non-tacky.

[0154] The compositions according to the first, second or third aspects of the invention, the substrates to which the compositions are applied, or the multi-layer substrate structures to which the compositions are applied and / or incorporated may be suitable for end use as labels (adhesive or wraparound) and / or in high turnover consumer goods; packaging such as disposable packaging including food and hot or cold beverage containers; hygiene and personal care product packaging such as shampoo bottles; cosmetic packaging; decorative metalware; blister pack packaging; laminated pouches; medical and diagnostic devices and associated packaging.

[0155] The compositions, substrates and multi-layer substrate structures according to the present invention may find particular use in the packaging industry. The substrate or multi-layer substrate structure may typically be an article such as a packaging product including, but not limited to, paper-based and container boxes, including cardboard and cartonboard boxes, paper-based tubes, including cardboard tubes, plastic bottles, paper-based bottles, plastic lids, glass bottles, aluminum cans and lids, steel cans and lids, wrap-around labels, stretch sleeves, shrink sleeves, and self-adhesive labels.

[0156] According to a sixth aspect of the present invention there is provided a method of forming a composition according to the first, second or third aspect of the present invention, the method comprising the steps of heating the hot melt adhesive to a temperature equal to or above the melting temperature of the hot melt adhesive but below the melting or decomposition temperature of the colour forming compound and, if present, the melting temperature of the thermal acid generator, such that the hot melt adhesive melts, and mixing the colour forming compound and optionally the thermal acid generator and the infrared absorbing compound in the molten hot melt adhesive such that it is distributed throughout the molten hot melt adhesive.

[0157] With respect to the sixth aspect of the invention, the composition may have any of the features described as preferred or optional in relation to any other aspect of the invention.

[0158] For the formation of the composition, the hot melt adhesive is heated above its melting temperature so that it melts (said melting temperature of the hot melt adhesive is lower than the melting or decomposition temperature of the color-forming compound and, if applicable, the melting temperature of the thermal acid generator), and the color-forming compound is brought into contact with the molten hot melt adhesive, introduced thereto and mixed therewith. Alternatively, the hot melt adhesive and the color-forming compound are brought into contact and heated above the melting temperature of the hot melt adhesive (said melting temperature of the hot melt adhesive is lower than the melting or decomposition temperature of the color-forming compound and, if applicable, the melting temperature of the thermal acid generator), and then the color-forming compound is mixed into the molten hot melt adhesive. Furthermore, if the color-forming compound is a leuco dye and the composition further comprises a thermal acid generator, and / or if an infrared absorbing compound is present, it is understood that the thermal acid generator and / or the infrared absorbing compound are either introduced into the hot melt adhesive together with the color-forming compound in a molten state, or are brought into contact with the hot melt adhesive and the color-forming compound before heating. Furthermore, if the color-forming compound is a leuco dye, the leuco dye and the thermal acid generator may be separately brought into contact with a portion of the hot melt adhesive, which are then combined and heated above the melting temperature of the hot melt adhesive (said melting temperature of the hot melt adhesive is lower than the melting temperature of both the leuco dye and the thermal acid generator), and the leuco dye and the thermal acid generator present are mixed into the hot melt adhesive in this molten state. This also applies if an infrared absorbing compound is utilized in the composition.

[0159] It is understood that the color-forming compound, and, if present, the thermal acid generator or infrared absorbing compound, are introduced into the composition in solid particulate form.

[0160] In the method of forming the composition of the first, second or third aspect of the invention, the hot melt adhesive is heated to above its melting temperature so that the hot melt adhesive melts and becomes flowable. The melting temperature of the hot melt adhesive is as discussed above for the compositions of the first, second and third aspects of the invention. Preferably, the hot melt adhesive is heated to 50 to 200°C, or 50 to 160°C, for example 70 to 150°C.

[0161] As discussed above, the melting or decomposition temperature of the color-forming compound and, if applicable, the melting temperature of the thermal acid generator are not reached during formation of the composition according to the first, second or third aspect of the invention. The melting or decomposition temperature of the color-forming compound and, if applicable, the melting temperature of the thermal acid generator are as described above for the composition according to the first, second or third aspect of the invention.

[0162] Heating of the hot melt adhesive during the formation of the composition of the present invention may be accomplished by any means. Suitable heating equipment includes hot melt guns and applicators, extrusion and molding equipment, injection, blow molding, calendaring, rotational molding, thermoforming and hot melt coating machines. Fabrication of the composition can be accomplished using standard thermoplastic processing machinery, such as equipment used for extrusion, blending, mixing, grinding and molding, including injection and blow molding, as well as other conventional equipment of different sizes and specifications can be used for calendaring, rotational molding, thermoforming, hot melt coating. This can include processing using liquid or solid masterbatches, and processing in solid forms such as sticks, blocks, chunks, rods, spheres, beads, pellets, granules and powders.

[0163] It will be appreciated by those skilled in the art that once the composition is formed, when the hot melt adhesive is melted, the composition can be applied directly to a substrate or multi-layer substrate structure, or used to form the multi-layer substrate structures discussed above. The composition is then cooled to room temperature and solidifies on the substrate or multi-layer substrate structure, or the hot melt adhesive cools and transitions to a solid state during the formation of the multi-layer substrate structure.

[0164] Alternatively, once the composition is formed, it can be allowed to cool to room temperature and solidify so that the hot melt adhesive returns to a solid state. The composition is then in a generally solid state. The composition can then be stored or transported in the solid state, and if necessary, reheated to the melting temperature of the hot melt adhesive (selected to be lower than the melting or decomposition temperature of the color-forming compound and, if applicable, the melting temperature of the thermal acid generator) in order for the hot melt adhesive to melt and for the composition to be applied to a substrate or multi-layer substrate structure, or used to form a multi-layer substrate structure.

[0165] According to a seventh aspect of the present invention, there is provided a method of forming a substrate comprising a composition according to the first, second or third aspect of the present invention, onto which the composition has been applied, the method comprising the steps of heating the composition to a temperature equal to or higher than the melting temperature of the hot melt adhesive but below the melting temperature of the colour forming compound and, if present, the melting or decomposition temperature of the thermal acid generator or infrared absorbing compound, such that the hot melt adhesive melts; once the hot melt adhesive is melted, applying the composition to the substrate; and allowing the composition to cool and solidify on the substrate.

[0166] According to an eighth aspect of the present invention, there is provided a method of forming a multi-layer substrate structure comprising a composition according to the first, second or third aspect of the present invention, onto which the composition has been applied, the method comprising the steps of heating the composition to a temperature equal to or above the melting temperature of the hot melt adhesive but below the melting or decomposition temperature of the colour forming compound and, if present, the melting temperature of the thermal acid generator or infrared absorbing compound, such that the hot melt adhesive melts; once the hot melt adhesive is melted, applying the composition to a substrate; and allowing the composition to cool and solidify.

[0167] According to a ninth aspect of the present invention, there is provided a method of forming a multi-layer substrate structure having a composition according to the first, second or third aspects of the present invention, the composition being incorporated therein, the method comprising the steps of heating the composition to a temperature above the melting temperature of the hot melt adhesive but below the melting or decomposition temperature of the colour forming compound and, if present, the melting or decomposition temperature of the thermal acid generator or infrared absorbing compound, such that the hot melt adhesive melts; once the hot melt adhesive is melted, applying the composition to a substrate; and contacting the substrate with another substrate with the composition located therebetween, such that the substrates are bonded together by the composition to form a multi-layer substrate structure.

[0168] For the seventh to ninth aspects of the invention, the composition, substrate or multi-layer substrate structure may have any of the features described as preferred or optional in relation to any other aspect of the invention.

[0169] It is understood that the composition is formed in accordance with the method of the fifth aspect of the invention described herein.

[0170] As discussed above, the composition may be applied to the outer surface of a substrate or multi-layer substrate structure, or to all, substantially all, or a portion of the surface area of ​​one of the substrates of the multi-layer substrate structure being formed.

[0171] As discussed above, the composition may be applied to the substrate or multi-layer substrate structure, or to the substrate of a multi-layer substrate structure during its formation using any suitable application method. Suitable application methods include, but are not limited to, hot melt guns and applicators, extrusion, injection molding, and molding equipment and coaters.

[0172] As discussed above, the composition may be applied to the substrate or multilayer substrate structure, or to the substrate of the forming multilayer substrate structure, as a single layer or multiple layers, i.e., one or multiple times. Preferably, the composition is applied to the substrate or multilayer substrate structure as a single layer.

[0173] With regard to the method of forming a substrate or multi-layer substrate structure of the present invention having a composition of the present invention thereon, it is understood that the composition, when melted, is applied to the substrate or multi-layer substrate structure and allowed to cool to room temperature and solidify. After application to the substrate or multi-layer substrate structure, the hot melt adhesive of the composition is transitioned to a solid state by allowing the composition to cool to room temperature and solidify. It is understood that if the hot melt adhesive used is non-tacky at room temperature, this cooling will result in the composition solidifying and becoming resistant to spalling during any subsequent handling, storage or use of the substrate or multi-layer substrate structure.

[0174] Typically, the time it takes for the composition to cool and solidify will depend on the amount of composition applied, i.e., the coat weight, but typically this will be from 0.1 to 100 seconds, for example 1 to 10 seconds, at room temperature.

[0175] The composition may be applied to a substrate or multi-layer substrate structure, or substrate of a multi-layer substrate structure, at any suitable coat weight depending on the substrate to which the composition is applied and the application method. It will be appreciated by those skilled in the art that the coat weight of the composition on the substrate will affect the intensity of the color formed by the color-forming compound. Preferably, the composition is applied to a coat weight of 0.1 to 1000 gsm (grams per square meter), for example, 0.1 to 500 gsm, or 0.1 to 250 gsm, most preferably 0.1 to 150 gsm. This coat weight is per individual layer of the composition applied to the substrate or multi-layer substrate structure, or substrate of a multi-layer substrate structure.

[0176] Coat weight of the composition may be measured by any suitable method. Suitable measuring methods are well known to those skilled in the art. Preferably, coat weight is measured by weighing the same area of ​​the substrate with and without the composition applied thereto, and comparing the two weights.

[0177] It will be appreciated by those skilled in the art that when the hot melt adhesive melts, the composition must be heated to a temperature above the melting temperature of the hot melt adhesive (but below the melting or decomposition temperature of the color-forming compound and, if present, the melting temperature of the thermal acid generator) in order to allow application of the composition to a substrate, a multi-layer substrate structure, or a substrate of a multi-layer substrate structure. This may be immediately after the formation of the composition while the hot melt adhesive is melted, or after storage of the composition where the composition is heated to a temperature above the melting temperature of the hot melt adhesive (but below the melting or decomposition temperature of the color-forming compound and, if present, the melting temperature of the thermal acid generator) so that the hot melt adhesive melts for application to the substrate. Suitable methods for heating the composition are well known to those skilled in the art and include typical industrial thermoplastic processing and application equipment, such as those used for extrusion, molding, injection, blow molding, calendaring, rotational molding, thermoforming, hot melt coating, glue guns and thermal glue applicators. It is understood that color and / or image formation may be facilitated by subsequent application of radiation because the composition is not heated to the melting or decomposition temperature of the color forming compound and, if present, the melting temperature of the thermal acid generator.

[0178] It is understood that for the methods of the seventh and eighth aspects of the present invention, after application to the substrate or multi-layer substrate structure, preferably the color-forming compound does not display color.

[0179] It is understood that for the method of the ninth aspect of the present invention, when the composition is melted, the substrates may be joined together and then cooled, so that the composition bonds the substrates together. Alternatively, if the hot melt adhesive, and thus the composition, is tacky at room temperature, the substrates may be joined once the composition has cooled and become solid but tacky at room temperature. Typically, the substrate, or at least one substrate, such as a polymeric film, of the multi-layer substrate structure is transparent or translucent, and upon application of radiation, any color and / or image formed is visible and human and / or machine readable. It is understood that the multi-layer structure may further comprise a substrate that bonds to at least two substrates discussed above, said further substrate being bonded by the same adhesive or by another adhesive that typically does not include a color-forming compound. Other adhesives are well known to those skilled in the art.

[0180] With respect to the method of the ninth aspect of the present invention, it is understood that the color-forming compounds preferably do not display color after incorporation into the multi-layer substrate structure.

[0181] For the substrates and methods of forming the substrates and multi-layer substrate structures of the present invention having the compositions of the present invention and onto which the compositions have been applied, or the methods of forming the substrates and multi-layer substrate structures of the present invention having the compositions of the present invention and into which the compositions have been incorporated, the melting temperature of the hot melt adhesive, and the melting or decomposition temperature of the color forming compound, and, if present, the thermal acid generator, of the composition are as described above for the present invention.

[0182] The compositions of the present invention allow for the formation of colors or images upon specific application of radiation.

[0183] According to a tenth aspect of the present invention there is provided a method of forming a colour and / or image on a substrate comprising a composition according to the first, second or third aspect of the present invention applied thereon, wherein the method optionally comprises the step of applying radiation to the composition to form a colour and / or image in the substrate.

[0184] According to an eleventh aspect of the present invention there is provided a method of forming colour and / or an image on and / or in a multi-layer substrate structure comprising a composition according to the first, second or third aspect of the present invention, onto which the composition has been applied and / or within which the composition has been incorporated, the method comprising the step of applying radiation to the composition as appropriate so as to form colour and / or an image on and / or in the multi-layer substrate structure.

[0185] Radiation can be applied to the composition at localized locations of the composition to selectively form colors and / or images. A human and / or machine readable image is formed. In the context of the present invention, it is understood that a color or image is formed because application of radiation to the composition reaches the melting or decomposition temperature of the color forming compound and, if applicable, the melting temperature of the thermal acid generator.

[0186] As discussed above, in the context of the present invention, it is understood that the color or image color formed upon application of radiation to the composition of the present invention is different from the color that the composition of the present invention may have prior to application of radiation upon formulation, storage, or application to and / or incorporation within a substrate or multi-layer substrate structure. The color and / or image color formed upon application of radiation to the composition is different from or has a stronger density than the color that those portion(s) of the composition to which radiation is not applied may have. The color-forming compound preferably displays color only in the portion(s) of the composition to which radiation is applied.

[0187] It will be appreciated by those skilled in the art that the radiation selected is that necessary to cause the color-forming compound to form a distinguishable color.

[0188] With respect to a multi-layer substrate structure having a composition therein, "applied to the composition" refers to the application of radiation to an area of ​​the multi-layer substrate structure in which the composition is disposed, thus effecting application of radiation to the composition.

[0189] For the tenth and eleventh aspects of the invention, the composition, substrate or multi-layer substrate structure may have any of the features described as preferred or optional in relation to any other aspect of the invention.

[0190] The term "image" incorporates, but is not limited to, marks such as logos, words or strings, graphics, figures, photographs, symbols, codes such as linear barcodes, two-dimensional Datamatrix, QR codes, Digimarc codes and strings, such as those based on alphanumeric characters and symbols. In the context of the present invention, it is recognized that it is the manipulation of a composition that includes a color-forming compound as an image-forming compound that facilitates the formation of an image. The formed image is human and / or machine readable and can be used for the purposes of coding and marking, tagging, tracking, tracing, and later-stage customization or personalization. The formed image is typically an image used to display variable information. The density of the image is measured by the ODB, ODY, ODM or ODC values, and the ΔODB, ΔODY, ΔODM or ΔODC values ​​described above.

[0191] In the context of the present invention, radiation is applied to the composition after it has cooled and solidified at room temperature, typically the composition being applied to a substrate or applied onto and / or incorporated within a multi-layer substrate structure.

[0192] "Radiation" and like terms used herein refer to energy in the form of waves or particles, particularly electromagnetic waves such as ultraviolet (UV), visible and infrared (IR), including near infrared (NIR), particle radiation such as alpha (α), beta (β), neutrons and plasma. The wavelength ranges in different regions of the electromagnetic spectrum are known to those of skill in the art.

[0193] It will be appreciated by those skilled in the art that the radiation applied to the composition will depend on the color forming compounds mixed therein. The radiation may be selected from ultraviolet (UV) radiation having a wavelength of 10-400 nm, visible light having a wavelength of 400-700 nm, infrared (IR) radiation having a wavelength of 700 nm to 1 mm, including near infrared (NIR) radiation having a wavelength of 700-1600 nm.

[0194] Preferably, the radiation is selected from infrared (IR) radiation having a wavelength of 9000 to 12000 nm (applied using a CO2 laser), infrared radiation having a wavelength of 700 nm to 1 mm, and near infrared (NIR) radiation having a wavelength of 700 to 1600 nm. More preferably, the radiation is selected from infrared (IR) radiation having a wavelength of 9000 to 12000 nm (applied using a CO2 laser), for example 9300, 9600, 10200 or 10600 nm (applied using a CO2 laser), or even 10600 nm (applied using a CO2 laser).

[0195] Radiation may be applied to the composition by any suitable means. Suitable means include laser excitation by application of radiation to the composition by a laser light source(s). Those skilled in the art will recognize that preferably, radiation is applied to the composition from a laser light source(s). Radiation can be applied to the composition at localized locations to selectively facilitate the formation of color and therefore image formation at these localized locations in the composition. These localized locations may overlap with each other. Those skilled in the art will also understand that radiation is applied to the composition for the appropriate amount of time necessary to facilitate the formation of an image. Typically, the time required to deliver sufficient radiation will depend on the means used to apply radiation and the method of application. For example, in one embodiment, radiation may be applied to the composition for less than 120 seconds, or less than 60 seconds, such as less than 20 seconds, or even less than 10 or 5 seconds.

[0196] When applied using a laser source(s), the radiation dose applied will depend on the time the radiation is applied, the power (wattage) of the means used to apply the radiation, and therefore the fluence (amount of energy delivered per unit area) delivered by the laser source(s), e.g., J / cm 2 It is understood that the fluence can be controlled by changing the amount of energy delivered per unit area. It will be understood by those skilled in the art that this can affect the density of the image formed. For example, if a laser light source(s) is used to apply the radiation, the fluence (amount of energy delivered per unit area) can affect the density of the image formed. In the context of the present invention, the fluence depends on the power (wattage) of the means used to apply the radiation, and the time that the radiation is applied to a particular local location of the substrate, which may be controlled by the scanning speed of the laser or the speed at which the stage is moved. These two variables can be changed to change the fluence. If the fluence is low (e.g., lower power and / or shorter exposure time), the image formed will have a lower optical density, and if the fluence is high (e.g., higher power and / or longer exposure time), the image formed will have a higher optical density and will be of higher contrast to the background of the composition. In the context of the present invention, fluence values ​​range from 0.01 to 50 J / cm 2 , e.g., 0.1 to 25 J / cm 2 , and 0.5 to 10 J / cm 2 may be in the range.

[0197] Preferably, radiation is applied to the composition at a localized location of the composition to form a desired image. Essentially, upon application of radiation, color is formed in the areas of the composition on the substrate to which the radiation is applied. The color forming compounds react to form color. A human and / or machine readable image is thus produced. It is the color forming compounds that function as the "image forming compounds" of the composition that enable the formation of the image.

[0198] According to a twelfth aspect of the present invention there is provided the use of a composition according to the first, second or third aspect of the present invention in the formation of a colour and / or image.

[0199] According to a thirteenth aspect of the present invention there is provided the use of a composition according to the first, second or third aspect of the present invention in the formation of a colour and / or image on a substrate having said composition, said substrate having said composition applied thereon.

[0200] According to a fourteenth aspect of the present invention there is provided the use of a composition according to the first, second or third aspect of the present invention in the formation of a colour and / or image on and / or within a multi-layer substrate structure having said composition, said multi-layer substrate structure onto which the composition has been applied and / or within which the composition has been incorporated.

[0201] For the twelfth to fourteenth aspects of the invention, the composition, substrate or multi-layer substrate structure may have any of the features described as preferred or optional in relation to any other aspect of the invention.

[0202] All of the features contained herein may be combined with any of the above aspects in any combination.

[0203] All references to "%" refer to the weight percent of the component in terms of the total composition or hot melt adhesive where specified.

[0204] For a better understanding of the present invention, and in order to show how embodiments thereof work, reference is now made to the following experimental data by way of example. EXAMPLES

[0205] [Example 1] 0.8 grams of an oxyanion of a polyvalent metal (ammonium octamolybdate (AOM)) and 0.8 grams of hot melt adhesive (obtained from 7mm hot melt adhesive glue sticks from HobbyCraft (product code: 6217411000)) were heated to 140°C (higher than the melting temperature of the hot melt adhesive but lower than the decomposition temperature of the AOM) in an aluminum foil tray using a hot plate. The hot melt adhesive melted, thereby mixing in the AOM. The composition was allowed to cool to room temperature and solidify. No color formation was observed due to the AOM. A Videojet VJ-3320 (10.6 μm) CO2 laser was used to apply IR radiation to one or more portions of the composition. As a result, the AOM formed color and a black image was formed, as shown in Figure 1.

[0206] [Example 2] 0.8 grams of an oxyanion of a polyvalent metal (ammonium octamolybdate (AOM)), 0.4 grams of an infrared or near infrared absorber (copper(II) hydroxyl phosphate (CHP)) and 1.2 grams of hot melt adhesive (obtained from 7mm hot melt adhesive glue sticks from HobbyCraft (product code: 6217411000)) were heated to 140°C (higher than the melting temperature of the hot melt adhesive but lower than the decomposition temperature of the AOM) in an aluminum foil tray using a hot plate. The hot melt adhesive melted and the AOM was mixed therewith. The composition was allowed to cool to room temperature and solidify. As shown in Figure 2A, no color formation was observed due to the AOM. A DataLase FL20 (1070 nm) NIR laser was used to apply NIR radiation to a portion(s) of the composition, which resulted in the AOM forming color and a black image being formed, as shown in Figure 2B. The optical density was changed by varying the fluence provided by the laser.

[0207] [Example 3] 0.5 grams of thermal acid generator (THPE), 0.25 grams of leuco dye (ETAC) and 0.75 grams of hot melt adhesive (obtained from 7mm hot melt adhesive glue sticks from HobbyCraft (product code: 6217411000)) were heated to 140°C (higher than the melting temperature of the hot melt adhesive but lower than the melting temperature of both the leuco dye and the thermal acid generator) in an aluminum foil tray using a hot plate. The hot melt adhesive melted and the leuco dye and the thermal acid generator were thereby mixed. The composition was allowed to cool to room temperature and solidify. No color formation was observed due to the leuco dye. A Videojet VJ-3320 CO2 laser was used to apply IR radiation to one or more portions of the composition, resulting in the leuco dye forming color and a black image being formed, as shown in Figure 3. The optical density was changed by varying the fluence provided by the laser.

[0208] [Example 4] Formulation 1 0.5 grams of thermal acid generator (N,N-dibutylbutan-1-aminium bis[2-(hydroxy-kO)benzoate(2-)-kO]borate(1-)) and 1.0 grams of hot melt adhesive (obtained from 7 mm hot melt adhesive glue sticks from HobbyCraft (product code: 6217411000)) were heated to 140° C. in an aluminum foil tray using a hot plate. The hot melt adhesive melted, thereby mixing the thermal acid generator. As shown in FIG. 4A, no color formation was displayed.

[0209] Formulation 2 0.5 grams of leuco dye (ETAC) and 1.0 grams of hot melt adhesive (obtained from 7 mm hot melt adhesive glue sticks from HobbyCraft (product code: 6217411000)) were heated to 140° C. in an aluminum foil tray using a hot plate. The hot melt adhesive melted, thereby mixing the leuco dye. No color formation was observed, as shown in FIG. 4B.

[0210] 0.1 grams of Formulation 1 and 0.1 grams of Formulation 2 were heated in an aluminum foil tray using a hot plate to 125° C. (above the melting temperature of the hot melt adhesive but below the melting temperature of both the leuco dye and the thermal acid generator). The hot melt adhesive melted, thereby mixing the leuco dye and the thermal acid generator. The composition was allowed to cool to room temperature and solidify. No color formation was observed due to the leuco dye. A Videojet VJ-3320 CO2 laser was used to apply IR radiation to one or more portions of the composition, resulting in the leuco dye forming color and a black image, as shown in FIG. 4C. The optical density was varied by varying the fluence provided by the laser.

[0211] [Example 5] Formulation 3 0.5 grams of leuco dye (ODB-2:Wincon-2) and 1.0 grams of hot melt adhesive (obtained from 7 mm hot melt adhesive glue sticks from HobbyCraft (product code: 6217411000)) were heated to 140° C. in an aluminum foil tray using a hot plate. The hot melt adhesive melted, thereby mixing the leuco dye. As shown in FIG. 5A, no color formation was observed.

[0212] 0.1 grams of Formulation 1 and 0.1 grams of Formulation 3 were heated in an aluminum foil tray using a hot plate to 125° C. (above the melting temperature of the hot melt adhesive but below the melting temperature of both the leuco dye and the thermal acid generator). The hot melt adhesive melted, thereby mixing the leuco dye and the thermal acid generator. The composition was allowed to cool to room temperature and solidify. No color formation was observed due to the leuco dye. A Videojet VJ-3320 CO2 laser was used to apply IR radiation to a portion(s) of the composition, which resulted in the leuco dye forming color and a black image being formed, as shown in FIG. 5B. The optical density was varied by varying the fluence provided by the laser.

[0213] [Example 6] Formulation 4 0.5 grams of thermal acid generator (THPE) and 1.0 grams of hot melt adhesive (obtained from 7 mm hot melt adhesive glue sticks from HobbyCraft (product code: 6217411000)) were heated to 140° C. in an aluminum foil tray using a hot plate. The hot melt adhesive melted, thereby mixing in the thermal acid generator. No color formation was observed, as shown in FIG. 6A.

[0214] 0.1 grams of Formulation 4 and 0.1 grams of Formulation 2 were heated in an aluminum foil tray using a hot plate to 140° C. (above the melting temperature of the hot melt adhesive but below the melting temperature of both the leuco dye and the thermal acid generator). The hot melt adhesive melted, thereby mixing the leuco dye and the thermal acid generator. The composition was allowed to cool to room temperature and solidify. No color formation was observed due to the leuco dye. A Videojet VJ-3320 CO2 laser was used to apply IR radiation to a portion(s) of the composition, resulting in the leuco dye forming color and a black image, as shown in FIG. 6B. The optical density was varied by varying the fluence provided by the laser.

[0215] [Example 7] 0.1 grams of Formulation 4 and 0.1 grams of Formulation 3 were heated in an aluminum foil tray using a hot plate to 140° C. (above the melting temperature of the hot melt adhesive but below the melting temperature of both the leuco dye and the thermal acid generator). The hot melt adhesive melted, thereby mixing the leuco dye and the thermal acid generator. The composition was allowed to cool to room temperature and solidify. No color formation was observed by the leuco dye. A Videojet VJ-3320 CO2 laser was used to apply IR radiation to a portion(s) of the composition, resulting in the leuco dye forming color and a black image, as shown in FIG. 7. The optical density was varied by varying the fluence provided by the laser.

[0216] [Example 8] 4.0 grams of an oxyanion of a polyvalent metal (ammonium octamolybdate (AOM)) and 4.0 grams of hot melt adhesive (obtained from a 7 mm hot melt adhesive glue stick from HobbyCraft (product code: 6217411000)) were heated in a dish using a hot plate to 140° C. (higher than the melting temperature of the hot melt adhesive but lower than the decomposition temperature of the AOM). The hot melt adhesive melted, thereby mixing in the AOM. As shown in FIG. 8A, no color formation was displayed by the AOM.

[0217] The composition was applied to a brown box liner using a "bird bar" applicator with a gap size of 25 μm while the hot melt adhesive, and therefore the composition, was melted. The composition was allowed to cool to room temperature on the substrate and solidify. As shown in FIG. 8B, no color formation was displayed by the AOM. A Videojet VJ-3320 CO2 laser was used to apply IR radiation to one or more portions of the composition, resulting in the AOM forming color and producing a black image, as shown in FIG. 8C. The optical density was changed by varying the fluence provided by the laser.

[0218] [Example 9] 2.5 grams of thermal acid generator (THPE), 1.5 grams of leuco dye (ETAC) and 4.0 grams of hot melt adhesive (obtained from a 7 mm hot melt adhesive glue stick from HobbyCraft (product code: 6217411000)) were heated in a dish using a hot plate to 140° C. (higher than the melting temperature of the hot melt adhesive but lower than the melting temperature of both the leuco dye and the thermal acid generator). The hot melt adhesive melted, thereby mixing the leuco dye and the thermal acid generator. No color formation was observed by the leuco dye.

[0219] The composition was applied to white carton board using a "Bird Film" applicator with a gap size of 25 μm while the hot melt adhesive, and therefore the composition, was molten. The composition was allowed to cool to room temperature on the substrate and solidify. No color formation was observed due to the leuco dye. A Videojet VJ-3320 CO2 laser was used to apply IR radiation to one or more portions of the composition, resulting in the leuco dye forming color and a black image being produced, as shown in Figure 9. The optical density was varied by varying the fluence provided by the laser.

[0220] [Example 10] 2.5 grams of thermal acid generator (N,N-dibutylbutan-1-aminium bis[2-(hydroxy-kO)benzoato(2-)-kO]borate(1-), 1.5 grams of leuco dye (ETAC) and 5 grams of hot melt adhesive (obtained from 7mm hot melt adhesive glue sticks from HobbyCraft (product code: 6217411000)) were heated in a dish using a hot plate to 125°C (higher than the melting temperature of the hot melt adhesive but lower than the melting temperature of both the leuco dye and the thermal acid generator). The hot melt adhesive melted, thereby mixing the leuco dye and the thermal acid generator. No color formation was observed by the leuco dye.

[0221] The composition was applied to a brown box liner using a "Bird Film" applicator with a gap size of 25 μm while the hot melt adhesive, and therefore the composition, was melted. The composition was allowed to cool to room temperature on the substrate and solidify. No color formation was observed due to the leuco dye. A Videojet VJ-3320 CO2 laser was used to apply IR radiation to one or more portions of the composition, resulting in the leuco dye forming color and a black image being produced, as shown in Figure 10. The optical density was varied by varying the fluence provided by the laser.

[0222] [Example 11] 2.5 grams of thermal acid generator (THPE), 1.5 grams of leuco dye (ETAC) and 4.0 grams of hot melt adhesive (obtained from a 7 mm hot melt adhesive glue stick from HobbyCraft (product code: 6217411000)) were heated in a dish using a hot plate to 140° C. (higher than the melting temperature of the hot melt adhesive but lower than the melting temperature of both the leuco dye or the thermal acid generator). The hot melt adhesive melted, thereby mixing the leuco dye and the thermal acid generator. No color formation was observed by the leuco dye.

[0223] The composition was applied to a 96 μm PET (polyethylene terephthalate) transparent film from HiFi Films using a "Bird Film" applicator with a gap size of 25 μm while the hot melt adhesive, and therefore the composition, was melted. The composition was allowed to cool to room temperature on the substrate and solidify. No color formation was observed due to the leuco dye. A Videojet VJ-3320 CO2 laser was used to apply IR radiation to one or more portions of the composition, which resulted in the leuco dye forming color and a black image being formed, as shown in FIG. 11.

[0224] [Example 12] 2.5 grams of thermal acid generator (N,N-dibutylbutan-1-aminium bis[2-(hydroxy-kO)benzoato(2-)-kO]borate(1-)), 1.5 grams of leuco dye (ETAC) and 5 grams of hot melt adhesive (obtained from 7mm hot melt adhesive glue sticks from HobbyCraft (product code: 6217411000)) were heated in a dish using a hot plate to 125°C (higher than the melting temperature of the hot melt adhesive but lower than the melting temperature of both the leuco dye and the thermal acid generator). The hot melt adhesive melted, thereby mixing the leuco dye and the thermal acid generator. No color formation by the leuco dye was observed.

[0225] The composition was applied to a 96 μm PET (polyethylene terephthalate) transparent film from HiFi Films using a "Bird Film" applicator with a gap size of 25 μm while the hot melt adhesive, and therefore the composition, was melted. The composition was allowed to cool to room temperature on the substrate and solidify. No color formation was observed due to the leuco dye. A Videojet VJ-3320 CO2 laser was used to apply IR radiation to one or more portions of the composition, which resulted in the leuco dye forming color and a black image being formed, as shown in FIG. 12.

[0226] [Example 13] Oxyanions of polyvalent metals or their oxyacids or hydrates (ammonium paratungstate (NH4)) dried in an oven for 16 hours at 100°C and ground in a mortar and pestle 10 (H2W 12 O 42 0.5 grams of .4H2O and 1.0 grams of hot melt adhesive (obtained from a 7 mm hot melt adhesive glue stick from HobbyCraft (product code: 6217411000)) were heated in an aluminum foil tray using a hot plate to 140°C (higher than the melting temperature of the hot melt adhesive but lower than the decomposition temperature of the anhydrous ammonium salt of the oxyanion of a polyvalent metal). The hot melt adhesive melted, thereby mixing with the anhydrous ammonium salt of the oxyanion of a polyvalent metal. The composition was allowed to cool to room temperature and solidify. As shown in Figure 13A, no color formation was observed due to the anhydrous ammonium salt of the oxyanion of a polyvalent metal. A Videojet VJ-3320 (10.6 μm) CO2 laser was used to apply IR radiation to a portion(s) of the composition, which resulted in the anhydrous ammonium salt of the oxyanion of a polyvalent metal forming color and forming a black image as shown in Figure 13B. The optical density was varied by varying the fluence provided by the laser.

[0227] [Example 14] 20% by weight of a polyvalent metal oxyanion or its oxyacid or hydrate (ammonium octamolybdate (AOM)) and 80% by weight of a hot melt adhesive (obtained from Caswell Adhesives) were heated to a temperature above the melting temperature of the hot melt adhesive but below the decomposition temperature of the AOM. The hot melt adhesive melted, thereby mixing in the AOM. No color formation due to the AOM was observed.

[0228] The composition was applied to a paper-based release liner while the hot melt adhesive, and therefore the composition, was molten. The composition was allowed to cool to room temperature on the substrate and solidify. No color formation was observed by the AOM. A Videojet VJ-3320 CO2 laser (10.6 μm) was used to apply IR radiation to one or more portions of the composition, which resulted in the AOM forming color and forming a black image as shown in Figures 14 to 17.

[0229] [Example 15] 3.5 grams of a polyvalent metal oxyanion or its oxyacid or hydrate (ammonium octamolybdate (AOM)) and 6.5 grams of a hot melt adhesive (Formulation 5) were heated to 150° C. (above the melting temperature of the hot melt adhesive but below the decomposition temperature of the AOM). The hot melt adhesive melted, thereby mixing in the AOM. No color formation was observed due to the AOM.

[0230] Formulation 5

[0231] [Table 1]

[0232] The compositions were applied separately to a paper-based release liner, a 96 μm PET (polyethylene terephthalate) clear film from HiFi Film, and cardboard while the hot melt adhesive, and therefore the composition, was melted. The compositions were allowed to cool to room temperature on the substrate and solidify. No color formation was observed with the AOM. A Videojet VJ-3320 CO2 laser with a 190 mm lens (10.6 μm) was used to apply IR radiation to one or more portions of the composition, resulting in the AOM forming color and forming a black image, as shown in Figures 18 to 20.

[0233] Comparative Example [Comparative Example 1] Formulation 6 0.5 grams of thermal acid generator 4-hydroxyphenyl-4'-isopropoxyphenyl sulfone (Chameleon Developer-1) and 1.0 grams of hot melt adhesive (obtained from a 7 mm hot melt adhesive glue stick from HobbyCraft) were heated to 140°C in an aluminum foil tray using a hot plate. The hot melt adhesive melted, thereby mixing the thermal acid generator. No color formation was observed, as shown in Figure 21A.

[0234] 0.1 grams of Formulation 5 and 0.1 grams of Formulation 2 were heated in an aluminum foil tray using a hot plate to 140° C. (higher than the melting temperature of the hot melt adhesive and higher than the melting temperature of one or both of the leuco dye and the thermal acid generator). The hot melt adhesive melted, thereby mixing the leuco dye and the thermal acid generator. The leuco dye formed a black color as shown in FIG. 21B. Thus, subsequent application of radiation to form an image was not possible.

[0235] [Comparative Example 2] 0.1 grams of Formulation 5 and 0.1 grams of Formulation 3 were heated in an aluminum foil tray using a hot plate to 125° C. (higher than the melting temperature of the hot melt adhesive and higher than the melting temperature of either or both of the leuco dye and the thermal acid generator). The hot melt adhesive melted and the leuco dye and the thermal acid generator were thereby mixed. The leuco dye formed a black color as shown in FIG. 22. Thus, subsequent application of radiation to form an image was not possible.

[0236] [Comparative Example 3] 0.75 grams of thermal acid generator 4-hydroxyphenyl-4'-isopropoxyphenylsulfone (Chameleon Developer-1), 0.75 grams of leuco dye 3-di-n-butylamino-6-methyl-7-phenylaminofluoran (ODB-2:Wincon-2) and 1.5 grams of hot melt adhesive (obtained from a 7 mm hot melt adhesive glue stick from HobbyCraft) were heated in an aluminum foil tray using a hot plate to 125°C (higher than the melting temperature of the hot melt adhesive and higher than the melting temperature of either or both of the leuco dye and the thermal acid generator). The hot melt adhesive melted, thereby mixing the leuco dye and the thermal acid generator. As shown in Figure 23, the leuco dye formed a black color. Thus, subsequent application of radiation to form an image was not possible.

Claims

1. 1. A composition formed from a hot melt adhesive having a color forming compound mixed therein, said color forming compound being selected from a leuco dye and an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, wherein when said color forming compound is a leuco dye: (a) the leuco dye is selected from 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-xanthene]-3-one and 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[5-isobenzofuran-1(3H),9'-[9H]xanthene]-3-one; (b) the hot melt adhesive further has a thermal acid generator mixed therein, the thermal acid generator being selected from 1,1,1-tris(4-hydroxyphenyl)ethane (THPE), tri-n-butylammonium-4,4'-dioxo-4H,4'H-2,2'-spirobi[benzo[d][1,3,2]dioxaborinine]-2-uido, N,N-dibutylbutan-1-aminium bis[2-(hydroxy-kO)benzoato(2-)-kO]borate(1-), 4-hydroxy-4'-isopropoxydiphenylsulfone, (2,4-dihydroxyphenyl)phenylmethanone, 3-(3-tosylureido)phenyl-4-methylbenzenesulfonate, 3,4,5-trihydroxybenzoate propyl, and 4,4'-methanediyldiphenol; (c) the melting temperature of the hot melt adhesive is lower than the melting temperatures of both the leuco dye and the thermal acid generator; A composition, wherein when the color forming compound is an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, the melting temperature of the hot melt adhesive is lower than the decomposition temperature of the oxyanion of the polyvalent metal or an oxyacid or hydrate thereof.

2. A composition formed from a hot melt adhesive having a color forming compound and an infrared absorbing compound mixed therein, the color forming compound being selected from a leuco dye, or an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof; When the color forming compound is a leuco dye, the hot melt adhesive further has a thermal acid generator mixed therein, the melting temperature of the hot melt adhesive being lower than the melting temperatures of both the leuco dye and the thermal acid generator; A composition, wherein when the color forming compound is an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, the melting temperature of the hot melt adhesive is lower than the decomposition temperature of the oxyanion of the polyvalent metal or an oxyacid or hydrate thereof.

3. 2. The composition of claim 1, wherein the color forming compound is selected from ammonium octamolybdate and the following leuco dyes: 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-xanthene]-3-one, and 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[5-isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, and when the color forming compound is a leuco dye, the hot melt adhesive further has a thermal acid generator 1,1,1-tris(4-hydroxyphenyl)ethane mixed therein.

4. The hot melt adhesive may be made of poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymers; poly(ethylene acrylate) copolymers; acrylics; polyvinyl butyral; polyolefins such as polybutene, polyethylene and polypropylene, for example low density (LDPE) and high density (HDPE) polyethylene; polyamides such as ethylene diamine and hexamethylene diamine; nylon; polyesters including poly(lactic acid) (PLA), polyethylene terephthalate (PET), polyhydroxyalkanoates (PHA) and poly(glycolic acid) (PGA); polyurethanes; acrylics and styrene acrylate copolymers; styrene-isoprene-styrene block tri- and copolymers; polystyrene (PS); polycaprolactone; polycarbonate; fluoropolymers; elastomers;a thermoplastic polymer, copolymer, oligomer or mixture thereof selected from silicone rubber and polypyrrole, or a combination thereof, preferably the thermoplastic polymer, copolymer, oligomer or mixture thereof is selected from polyethylene terephthalate (PET), polyhydroxyalkanoate (PHA), poly(glycolic acid) (PGA), poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymer, low density polyethylene (LDPE), high density polyethylene, and poly(lactic acid) (PLA), preferably the thermoplastic polymer, copolymer, oligomer or mixture thereof is selected from polyhydroxyalkanoate (PHA), poly(glycolic acid) (PGA), poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymer, and low density polyethylene (LDPE); 4. The composition according to any one of claims 1 to 3, wherein the thermoplastic polymer, copolymer, oligomer or mixture thereof is selected from polyhydroxyalkanoates (PHAs), poly(glycolic acid) (PGA), and poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymers, more preferably the thermoplastic polymer, copolymer, oligomer is poly(ethylene-vinyl acetate) or ethylene-vinyl acetate copolymer, optionally the thermoplastic polymer, copolymer, oligomer or mixture thereof is a bioplastic or petroleum-based plastic thermoplastic polymer, copolymer, oligomer or mixture thereof, and / or the thermoplastic polymer, copolymer, oligomer or mixture thereof is recyclable, biodegradable and / or compostable.

5. 5. The composition according to any one of claims 1 to 4, wherein the hot melt adhesive has a melt flow index of 1 to 1000 g / 10 min, preferably 100 to 1,000 g / 10 min, more preferably 500 to 900 g / 10 min, and / or the hot melt adhesive has a melting point of 50 to 200°C, or 50 to 160°C, or 70 to 150°C.

6. When the color-forming compound is a leuco dye, the thermal acid generator is selected from 1,1,1-tris(4-hydroxyphenyl)ethane and N,N-dibutylbutan-1-aminium bis[2-(hydroxy-kO)benzoato(2-)-kO]borate(1-), preferably 1,1,1-tris(4-hydroxyphenyl)ethane; and / or when the color-forming compound is an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, the oxyanion of a polyvalent metal or an oxyacid or hydrate thereof is a polyvalent metal.

6. The composition according to claim 1, and claim 4 or 5 depending from claim 1, wherein the oxyanion is a hydrate of an oxyanion of a group of polyvalent metals or an oxyanion of a polyvalent metal, preferably sodium molybdate dihydrate, or an ammonium salt of an oxyanion of a polyvalent metal, preferably sodium molybdate dihydrate, or an ammonium salt of an oxyanion of molybdenum, preferably sodium molybdate dihydrate, or ammonium octamolybdate (AOM), more preferably ammonium octamolybdate (AOM).

7. 10. A composition according to claim 1 or 6, or claim 4 or 6 depending from claim 1, wherein the colour forming compound is an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, preferably an oxyanion of a polyvalent metal or a hydrate of an oxyanion of a polyvalent metal, preferably sodium molybdate dihydrate, or an ammonium salt of an oxyanion of a polyvalent metal, preferably sodium molybdate dihydrate, or an ammonium salt of an oxyanion of molybdenum, preferably sodium molybdate dihydrate, or ammonium octamolybdate (AOM), more preferably ammonium octamolybdate (AOM).

8. When the color-forming compound is a leuco dye, the leuco dye may be selected from the group consisting of 3-di-n-butylamino-6-methyl-7-phenylaminofluoran (ODB-2: Wincon-2); 3-(N-ethyl-N-p-tolylamino)-6-methyl-7-anilinofluoran or 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (ETAC); 6-(dimethylamino)-3,3-bis[4-(dimethylamino)phenyl]phthalide (Blue I2R- Crystal Violet Lactone); and 3,3'-bis(1-n-octyl-2-methylindol-3-yl)phthalide (Red I6B), 2-anilino-3-diethylamino-6-methylethylfluoran (Chameleon Black 1), 2-anilino-6-dibutylamino-3-methylfluoran (Chameleon Black 2), 6-(dimethylamino)-3,3-bis[4-(dimethylamino)phenyl]phthalide (Chameleon Blue 3), 4,4'-[(9-butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N- phenylaniline] (Chameleon Blue 4), 3,3'-bis(1-n-octyl-2-methylindol-3-yl)phthalide (Chameleon Red 5), 6'-(diethylamino)-3-oxo-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-2'-carboxylic acid ethyl ester (Chameleon Orange 6), 7-[4-(diethylamino)-2-ethoxyphenyl]-7-(2-methyl-1-octyl-1H-indol-3-yl)furo[3,4-b]pyridin-5(7H)-one (Chameleon Blue 8), 2'- (Dibenzylamino)-6'-(diethylamino)fluoran (Chameleon Green 9), N,N-dimethyl-4-[2-[2-(octyloxy)phenyl]-6-phenyl-4-pyridinyl]-benzenamine (Chameleon Yellow 10), 6'-(diethylamino)-2'-[(dimethylphenyl)amino]-3'-methylspiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (Chameleon Black 15), 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-Xanthene]-3-one (CAS No. 89331-94-2) (ODB-2 / Wincon-2), 6'-(diethylamino)-3'-methyl-2'-(phenylamino)spiro[2-benzofuran-3,9'-xanthene]-1-one (CAS No. 29512-49-0) (ODB-1 / Wincon-1), 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (CAS No. 59129-79-2), 6-(dimethylamino)-3,3-bis-[4-(dimethylamino)phenyl]phthalide (Blue 3-CVL, CAS No. 1522-42-7), 4,4'-[(9-butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline] (Blue-4, CAS No. 67707-04-4), 3,3'-bis(1-n-octyl-2-methylindol-3-yl)phthalide (Red-5, CAS No. 50292-95-0), 6'-(diethylamino)-3-oxo-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-2'-carboxylic acid ethyl ester (Orange-6, CAS No. No. 154306-60-2), 7-[4-(diethylamino)-2-ethoxyphenyl]-7-(2-methyl-1-octyl-1H-indol-3-yl)furo[3,4-b]pyridin-5(7H)-one (Blue-8, CAS No. 87563-89-1), 2'-(dibenzylamino)-6'-(diethylamino)fluoran (Green-9, CAS No. 34372-72-0), N,N-dimethyl-4-[2-[2-(octyloxy)phenyl]-6-phenyl-4-pyridinyl]-benzenamine (Yellow-10, CAS No. No. 144190-25-0), 6'-(diethylamino)-2'-[(dimethylphenyl)amino]-3'-methylspiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (Black-15, CAS No. 36431-22-8), 2-anilino-6-dibutylamino-3-methylfluoran, 6-(dimethylamino)-3,3-bis[4-(dimethylamino)phenyl]phthalide, 4,4'-[(9-butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline], 3,3'-bis(1-n-octyl-2-methylindol-3-yl)phthalide, 6'-(diethylamino)-3-oxo-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-2'-carboxylic acid ethyl ester, 7-[4-(diethylamino)-2-ethoxyphenyl]-7-(2-methyl-1-octyl-1H-indol-3-yl)furo[3,4-b]pyridine-5 (7H)-one, 2'-(dibenzylamino)-6'-(diethylamino)fluoran, N,N-dimethyl-4-[2-[2-(octyloxy)phenyl]-6-phenyl-4-pyridinyl]-benzenamine, and 6'-(diethylamino)-2'-[(dimethylphenyl)amino]-3'-methylspiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, 4,4'-[(9-butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline] (CAS No. 67707-04-4), 6'-(diethylamino)-3-oxospiro[isobenzofuran-1(3H),9'-(9H)xanthene]-2' carboxylic acid ethyl ester (CAS No. 154306-60-2), and 2'-(dibenzylamino)-6'-(diethylamino)fluoran (CAS No. 34372-72-0), and preferably said leuco dye is selected from 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-xanthene]-3-one, 6'-(diethylamino)-3'-methyl-2'-(phenylamino)spiro[2-benzofuran-3,9'-xanthene]-1-one and 2-anilino-6'-[ethyl( p-tolyl)amino]-3'-methylspiro[5-isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, preferably 2'-anilino-6'-(dibutylamino)-3'-methyl-3H-spiro[2-benzofuran-1,9'-xanthene]-3-one and 2-anilino-6'-[ethyl(p-tolyl)amino]-3'-methylspiro[5-isobenzofuran-1(3H),9'-[9H]xanthen]-3-one, and optionally said thermal acid generator is selected from 4-hydroxyphenyl-4'-isopropoxyphenylsulfone (Chameleon Developer-1); N-(p-toluenesulfonyl)-N'-(3-(p-toluenesulfonyloxy)phenyl)urea (Pergafast 201); thermal acid generators based on 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) and amine salts of borobenzilate and tri-n-butylammonium borodisalicylate, such as N,N-dibutylbutan-1-aminium bis[2-(hydroxy-kO)benzoato(2-)-kO]borate(1-), tri-n-butylammonium-4,4'-dioxo-4H,4'H-2,2'-spirobi[benzo[d][1,3,2]dioxabo linine]-2-uido, as well as 4-hydroxy-4'-isopropoxydiphenylsulfone, (2,4-dihydroxyphenyl)phenylmethanone, 3-(3-tosylureido)phenyl-4-methylbenzenesulfonate, 3,4,5-trihydroxybenzoic acid propyl and 4,4'-methanediyldiphenol, preferably N,N-dibutylbutan-1-aminium bis[2-(hydroxy-kO)benzoato(2-)-kO]borate(1-), 1,1,1-tris(4-hydroxyphenyl)ethane (THPE), tri-n-butylammonium-4,4'-dioxo-4H,4'H-2,2'-spirobi[benzo[d][1,3,2]dioxaborinine]-2-uido, 4-hydroxy-4'-isopropoxydiphenylsulfone, (2,4-dihydroxyphenyl)phenylmethanone, 3-(3-tosylureido)phenyl-4-methylbenzenesulfonate, or 3,4,5-trihydroxyammonium The composition according to claim 2, and claim 4 or 5 depending on claim 2, wherein the diphenyl ether is selected from propyl benzoate and 4,4'-methanediyldiphenol, more preferably N,N-dibutylbutane-1-aminium bis[2-(hydroxy-kO)benzoato(2-)-kO]borate(1-) and 1,1,1-tris(4-hydroxyphenyl)ethane (THPE), more preferably 1,1,1-tris(4-hydroxyphenyl)ethane (THPE).

9. 10. A composition according to claim 2 or 8, or claim 4 or 5 depending from claim 2, wherein when the colour forming compound is an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, the oxyanion of a polyvalent metal or an oxyacid or hydrate thereof is an oxyanion of a polyvalent metal or a hydrate of an oxyanion of a polyvalent metal, preferably sodium molybdate dihydrate, or an ammonium salt of an oxyanion of a polyvalent metal, preferably sodium molybdate dihydrate, or an ammonium salt of an oxyanion of molybdenum, preferably sodium molybdate dihydrate, or ammonium octamolybdate (AOM), more preferably ammonium octamolybdate (AOM).

10. 10. A composition according to claim 2, 8 or 9, or claim 4 or 5 dependent on claim 2, wherein the colour forming compound is an oxyanion of a polyvalent metal or an oxyacid or hydrate thereof, preferably an oxyanion of a polyvalent metal or a hydrate of an oxyanion of a polyvalent metal, preferably sodium molybdate dihydrate, or an ammonium salt of an oxyanion of a polyvalent metal, preferably sodium molybdate dihydrate, or an ammonium salt of an oxyanion of molybdenum, preferably sodium molybdate dihydrate or ammonium octamolybdate (AOM), more preferably ammonium octamolybdate (AOM).

11. 6. A composition according to claim 3, or claim 4 or 5 depending from claim 3, wherein the colour forming compound is ammonium octamolybdate (AOM).

12. 13. The composition of claims 1, 3, 6, 7, and 11, or claims 4 or 5 depending from claims 1 or 3, wherein the hot melt adhesive further has an infrared absorbing compound mixed therein.

13. The infrared absorber may be an inorganic copper salt such as copper(II) hydroxyl phosphate (CHP); an organic NIR dye and pigment such as N,N,N',N'-tetrakis(4-dibutylaminophenyl)-p-benzoquinone bis(iminium hexafluoro-antimonate); an organic NIR dye and pigment such as reduced indium tin oxide, reduced zinc oxide, reduced tungsten oxide, an inorganic copper salt such as copper(II) hydroxyl phosphate (CHP ... N,N,N',N'-tetrakis(4-dibutylaminophenyl)-p-benzoquinone bis(iminium hexafluoro-antimonate); an organic NIR dye and pigment such as reduced indium tin oxide, reduced zinc oxide, reduced tungsten oxide, an inorganic NIR dye and pigment such as copper(II) hydroxyl phosphate (CHP); At least one element selected from the group consisting of Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I, W is tungsten, and O is oxygen, satisfying 0.001≦x / y≦1; and 2.2≦z / y≦3.

0. [0023] The infrared absorbing compound is selected from inorganic copper salts such as copper(II) hydroxyl phosphate (CHP); reduced indium tin oxide, reduced zinc oxide, reduced tungsten oxide, non-stoichiometric reduced or doped inorganic compounds such as doped metal oxides such as aluminum doped zinc oxide (AZO) and fluorine doped tin oxide (FTO); conductive polymers such as polystyrene sulfonate (PEDOT); and combinations thereof, preferably the infrared absorbing compound is selected from inorganic copper salts such as copper(II) hydroxyl phosphate (CHP); reduced indium tin oxide, reduced zinc oxide, reduced tungsten oxide, 13. The composition of claim 2 or claim 12, wherein M is at least one element selected from the group consisting of H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi and I, W is tungsten, and O is oxygen, and wherein 0.001≦x / y≦1; and 2.2≦z / y≦3.

0.

14. A substrate comprising the composition of any one of claims 1 to 13, on which the composition is applied.

15. 14. A multi-layer substrate structure comprising the composition of any one of claims 1 to 13, on which the composition is applied and / or within which the composition is incorporated.

16. 16. The substrate or multi-layer substrate structure of claim 14 or 15, wherein the composition is on the exterior of the substrate or multi-layer substrate structure so as to be exposed, and / or the substrate or multi-layer substrate structure is a packaging product, preferably including paper-based and container boxes, including cardboard and cartonboard boxes, paper-based tubes, including cardboard tubes, plastic bottles, paper-based bottles, plastic lids, glass bottles, aluminum cans and lids, steel cans and lids, wrap-around labels, stretch sleeves, shrink sleeves, and self-adhesive labels.

17. 17. The substrate or multi-layer structure of any one of claims 14 to 16, wherein the hot melt adhesive of the composition is a bioplastic thermoplastic polymer, copolymer, oligomer or mixture thereof, and the substrate or multi-layer substrate structure is formed from a bioplastic material.

18. 14. A method of forming a composition according to any one of claims 1 to 13, comprising the steps of heating the hot melt adhesive to a temperature equal to or higher than the melting temperature of the hot melt adhesive, but lower than the melting or decomposition temperature of the colour forming compound and, if present, the melting temperature of the thermal acid generator or infrared absorbing compound, so that the hot melt adhesive melts, and mixing the colour forming compound and optionally the thermal acid generator and infrared absorbing compound in the molten hot melt adhesive so that they are distributed throughout the molten hot melt adhesive.

19. 14. A method of forming a substrate comprising the composition of any one of claims 1 to 13, onto which the composition has been applied, comprising the steps of: heating the composition to a temperature equal to or greater than the melting temperature of the hot melt adhesive, but below the melting or decomposition temperature of the color forming compound and, if present, the melting temperature of the thermal acid generator or infrared absorbing compound, such that the hot melt adhesive melts; once the hot melt adhesive is melted, applying the composition to the substrate; and allowing the composition to cool and solidify on the substrate.

20. 14. A method of forming a multi-layer substrate structure comprising the composition of any one of claims 1 to 13, onto which the composition has been applied, comprising the steps of: heating the composition to a temperature equal to or higher than the melting temperature of the hot melt adhesive, but lower than the melting or decomposition temperature of the color forming compound and, if present, the melting temperature of the thermal acid generator or infrared absorbing compound, such that the hot melt adhesive melts; once the hot melt adhesive is melted, applying the composition to the substrate; and allowing the composition to cool and solidify.

21. 14. A method of forming a multi-layer substrate structure comprising the composition of any one of claims 1 to 13, wherein said composition is incorporated therein, comprising the steps of: heating said composition to a temperature equal to or greater than the melting temperature of said hot melt adhesive, but less than the melting or decomposition temperature of said color forming compound, and, if present, the melting temperature of said thermal acid generator or infrared absorbing compound, such that said hot melt adhesive melts; once said hot melt adhesive has melted, applying said composition to said substrate; and contacting said substrate with another substrate with said composition located therebetween, such that said substrates are bonded together by said composition to form a multi-layer substrate structure.

22. 18. A method of forming a colour and / or an image on a substrate comprising a composition according to any one of claims 1 to 13, onto which said composition has been applied, or on a substrate according to claims 14, 16 or 17, comprising the step of applying radiation to said composition as appropriate so as to form a colour and / or an image on said substrate, preferably said radiation is applied from a laser source, more preferably said applied radiation is infrared (IR) radiation, and / or said colour forming compound does not display a colour before application of radiation but displays a colour after application of said radiation.

23. 17. A method of forming a color and / or image on and / or in a multi-layer substrate structure comprising the composition of any one of claims 1 to 13, on which the composition has been applied and / or incorporated therein, or on and / or in a multi-layer substrate structure of any one of claims 15 to 17, comprising the step of applying radiation to the composition as appropriate to form a color and / or image on and / or in the multi-layer substrate structure, preferably the radiation is applied from a laser source, more preferably the applied radiation is infrared (IR) radiation, and / or the color forming compound does not display a color prior to application of radiation, but displays a color after application of the radiation.

24. Use of a composition according to any one of claims 1 to 13 in the formation of a colour and / or image, preferably a substrate carrying said composition, onto which said composition has been applied.

25. 14. Use of a composition according to any one of claims 1 to 13 in the formation of colours and / or images on and / or within a multi-layer substrate structure having said composition, said composition being applied thereon and / or having said composition incorporated therein.

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