HK1118765B - Energy activated printing process - Google Patents

Description

Energy activated printing process

Technical Field

The present invention relates generally to printing methods, and more particularly to methods of printing images using reactive printing inks.

Background

Known imaging printing methods and processes for substrates other than paper lack print strength and durability due to fibrillation problems. Images can "fade" due to laundering and abrasion in everyday use, especially when the substrate is a fabric or textile material. Fibrillation is the term used by the textile industry to describe small lint of fibers that breaks away from the fabric material and remains on the surface of the fabric or fabric, which results in a significant reduction in color intensity. Fibrillation is present in the knitted, woven or non-woven textile when natural fibres, such as cellulose or modified cellulose fibres, are used at least as part of the textile fabric.

Pigments or dyes used in many printing processes are opaque or mixtures of opaque binder materials. They provide good opacity, but do not have a high level of image or color vividness. This problem is even more pronounced when cotton or similar natural fiber materials are used in textile substrates due to the opacity of these materials. Thus, there remains a need for digital printing processes that provide permanent fixation of images on fibrous natural or synthetic substrates, and provide good color fastness, vividness and brightness, permanence and satisfactory "hand".

The use of computer technology allows for substantially instantaneous printing of images. For example, a camera or scanner on a computer may be used to capture color images. Images generated or stored on a computer can be printed on command regardless of batch size. The image may be printed from the computer onto the substrate by any suitable printing device capable of printing in multiple colors, including mechanical thermal printers, inkjet printers, and electrophotographic or electrostatic printers.

Disclosure of Invention

The present invention relates to printing. More particularly, the present invention relates to reactive inks and methods of producing images on substrates using reactive and energy activated inks. An image is printed on a substrate without reacting the reactive agent in the ink. The reagents are then allowed to react to fix the image to the substrate substantially permanently and securely. The ink may or may not contain a colorant. The sublimation or similar heat-activated dyes may be printed with the reactive ink by means of an additional printing step, printing the colorant in the form of an image, or in a separate printing step. The sublimating or similarly heat-activated dye is activated and has an affinity for the polymer present on the substrate.

Detailed Description

In a preferred embodiment of the present invention, a toner or ink is prepared that comprises components selected from each of two sets of reactive materials. The ink or toner may further comprise one or more colorants, carriers, or printing additives.

The first reactive species may be an electrophilic crosslinking agent capable of crosslinking the nucleophilic compound. Preferred crosslinking agents are isocyanates, diisocyanates including 4, 4 '-methylene diphenyl diisocyanate (MDI), 2, 4-, 2, 6-Toluene Diisocyanate (TDI), 1, 5-naphthalene diisocyanate (ND I), 1, 6-Hexamethylene Diisocyanate (HDI), 4' dicyclohexylmethane diisocyanate (H)₁₂MDI), 3-isocyanatomethyl-3, 5, 5-trimethylcyclohexyl isocyanate or isophorone diisocyanate (IPDI), p-phenylene diisocyanate, cyclohexyl diisocyanate, 2, 4-trimethyl-1, 6-hexamethylene diisocyanate (TMDI), 3 '-tolidene-4, 4' -diisocyanate, 3 '-dimethyl-diphenylmethane-4, 4' -diisocyanate, isothiocyanates, carbodiimides and polycarbodiimides, triazines and ammoniaAminotriazines, such as methoxymethylmelamine crosslinker, aziridines and polyfunctional aziridines, polyacrylamides, acetoacetoxy-functional polymeric crosslinkers, melamine resins such as tris (methoxy) methylmelamine (TMMM), Hexamethoxymethylmelamine (HMMM) or other modified melamine resins such as acrylated melamine, benzoguanamine, urea crosslinking resins, reactive silanes or reverse-protected silanes (RPS), cyclic polycarboxylic acids or anhydrides, carbonates such as alkylene carbonates, including ethylene, propylene, butylene, glycerol, hydroxyethyl and hydroxypropyl carbonates, or epoxy resins for the reaction obtainable by certain starting processes, such as blocked polyisocyanates, internally blocked (sometimes referred to as non-blocking agent) isocyanates or polyisocyanates, or encapsulated polyisocyanates, which can be initiated by the application of heat. Other ingredients, such as colorants, dispersants, binders, surfactants, and other additives may also be used as the nucleophilic/electrophilic reactive compound for immobilization.

The second reactive species may be nucleophilic compounds capable of crosslinking by active hydrogen-containing groups, such as amines or diamines, amide groups, dicyandiamide compounds, imines and polyethyleneimine, amine polyethers, polyvinyl alcohol (PVA), carboxylic acids, hydroxyl-containing, such as diols, triols, polyols, including polyester polyols, acrylate polyols, Styrene Allyl Alcohol (SAA) copolymer polyols, polyfunctional polyols, such as epoxide polyether polyols (novrypol 200 from Brian-Jones, United Kingdom), silicone polymers, including Polydimethylsiloxane (PDMS), hydroxyl-terminated polymers, copolymers such as hydroxyl-terminated polybutadiene, thiols, urethanes, or urea groups or functional groups that can be converted to active hydrogen-containing functional groups, such as carboxylic acid derivatives, for example, acid anhydride groups. In addition, final substrates containing active hydrogen, such as hydroxyl (cotton, rayon, and jute), amino (silk, nylon), or thiol (wool), may fully or partially accomplish this bonding process and provide bonding sites for the final image. The resulting inks are useful in printing processes on natural fabric substrates, or substrates comprising natural and synthetic materials, including textiles, fabrics, or fibrous materials, wherein the reactive species are present within the substrate, or on the surface of the substrate.

One or more coreactants may be used. The co-reactant may act as a nucleophilic compound capable of cross-linking through active hydrogen-containing groups, and may help to achieve lower chemical reaction energy requirements or heat requirements, and may shorten the time for a desired cross-linking and binding reaction of the ink or toner and/or the desired cross-linking and binding reaction between the ink or toner and the substrate. For example, the polyether co-reactant may help reduce the energy cut-off deblocking or blocking agent and lower the crosslinking temperature of the alcohol-capped aromatic polyisocyanate, and the aliphatic diamine co-reactant may help crosslink the phenol-capped aromatic polyisocyanate. Carbamates and secondary carbamates aid in the crosslinking of melamine resins, such as melamine-formaldehyde resins.

The ratio of the two reactive species may be present in stoichiometric balance of the reactive components. For example, depending on the functionality of the substrate, the ratio of equivalents of isocyanate groups to equivalents of active hydrogen-containing functional groups may be from 0.1: 1 to 100: 1, and may be 2: 1.

In another embodiment, the toner or ink may be comprised of a crosslinking compound or a compound containing functional groups that react with active hydrogen, while the substrate comprises an active hydrogen containing compound. For example, the toner or ink may contain isocyanate groups and the final substrate contains active hydrogen, such as cellulose. As an extension of this concept, the toner or ink may contain an active hydrogen-containing compound, while the substrate contains a compound having a functional group that reacts with active hydrogen. Such an ink-substrate combination is particularly helpful in creating a 3-dimensional cross-linked structure between the ink and the substrate in which small fibrous lint can participate in cross-linking, and in reducing or eliminating fibrillation.

In another embodiment, the two reactive groups may be present in separate toners or inks to avoid premature or undesirable activation or crosslinking reactions or sticking. For example, one ink jet print head can print an ink in which the component has a functional group that reacts with active hydrogen, while another print head can print an active hydrogen-containing component. To obtain highly cohesive images with reduced print defects while also producing image integrity and permanence, at least one of the two reactive components may be present in each colorant-containing ink, as well as in the colorless ink.

A camera or scanner may be used to capture the image. The image is provided to a computer. The computer directs a digital printer, which may be an ink jet printer or an electrographic device, such as a laser printer or a photocopier, to print the image. Other devices for forming images may be used, including images generated by software. Graphics software may be designed using available computers, or still photography may be used. The design may be photographic, graphic art, or simply a letter or word. The use of cyan, yellow, and magenta toner compositions allows printers to print full color or multi-color designs. An optional black toner may be used. Additionally, dot color may be used to increase the color gamut.

The image is printed directly on the final substrate or on an intermediate substrate, followed by transfer. The substrate may be composed of a material that can be printed thereon by an ink jet device, such as a continuous ink jet, a drop on demand device such as a thermal or bubble jet printer, a mechanical or electromechanical digital printing or coating device, or a piezoelectric ink jet printer.

In direct printing, the ink or toner can be printed directly onto the substrate without the need to sufficiently activate the reactive components (reagents) at the time of printing. Inks of the aqueous, anhydrous or sol-gel type may be used. When aqueous or alcohol-containing inks are used, the available reactive functional groups, such as hydroxyl groups, are increased by the printed ink via a swelling process. Better reactivity is obtained and improved image fastness is obtained after crosslinking and/or curing. This is particularly beneficial for substrates such as cotton, silk, wool, jute, where the participation of the microfibers in the crosslinking reaction at the surface of the substrate may significantly affect the image quality of the print. Different types of inks may also be used. For example, a water-based reactive ink without colorant may be printed to swell and debubble the fibrous material of the substrate, followed by printing a sol-gel type ink containing colorant to achieve both defect-free printing and superior brilliance of color after fixation or activation of the ink.

In another embodiment, a crosslinking agent such as polycarbodiimide may be stable in an anhydrous vehicle and may be printed without the need for other active hydrogen components to be present in the ink. The printing is performed by one print head to obtain activation and cross-linking before or after printing of the other inks printed by the other print heads. Many suitable functional groups are very reactive at ambient temperature and will initiate curing and crosslinking upon contact. This configuration allows the reactive ink components to be separated and printed without initiating a curing or crosslinking reaction.

To further prevent premature or undesired reactions, the functional groups of the crosslinkable compounds or components may be protected by chemical capping agents or by physical barriers such as encapsulation. Such protective agents are preferably removed via initiation methods by application of energy or heat, but other initiation methods include, but are not limited to, radiation, chemical reactions, pressure, and/or combinations thereof. Various printer platforms may be mixed and used in the present invention, for example, a combination of an electrographic printing device and a piezoelectric inkjet printing device.

In transfer, once an image is printed onto an intermediate substrate, the image may be immediately and permanently transferred to a final substrate, or the image may be ultimately transferred from the intermediate substrate to the final substrate. The design can be transferred to a textile substrate, such as a shirt, or other substrate, such as metal, ceramic, wood, or plastic. A wide selection of preferred final substrates is possible, including, but not limited to, textiles, and especially natural, semi-synthetic, or synthetic materials. Examples of natural textile materials include wool, silk, hair and cellulosic materials, especially cotton, rayon, jute, hemp, flax and linen. Examples of synthetic and semi-synthetic materials include polyamides, polyesters, polyacrylonitriles and polyurethanes. The textile material may be a blend of natural and synthetic fibers. When transferring, release paper coated with a low surface energy material, for example, a silicone polymer or fluorocarbon resin, such as polytetrafluoroethylene, and/or a release agent, such as carboxymethyl cellulose, may be used. "peel force" describes the force required to remove a layer from a liner/base sheet and can be subjectively described as "easy" or "tight". The release force can be adjusted by the choice of the coating formulation and the characteristics of the resulting polymer, or by the coating weight. Optimally, the peel force is such that it is high enough ("tight") that the ink or toner sticks during and after the fusing step within the printer and any subsequent processing of the printed image, but not so high that the ink or toner does not significantly peel from the sheet during transfer to the final substrate ("easy peel").

One or more blocking or protecting agents may also be used to prevent premature or undesired reaction of the reactive components. The capping agent provides protection for the reactants and may be removed or blocked during the transfer or immobilization step of the process by the application of energy, which may be heat.

The ink or toner is fixed to the final substrate as follows: the protective agent on the reactive component is removed by application of energy, such as heat, hot steam, radiation, or pressure, or a combination of these, and the first and second reactive species are allowed to react with each other and/or with the active hydrogen-containing groups on the final substrate. The transfer step can be accomplished in this case, for example, by applying heat at 200 c while applying pressure for 20 seconds.

The choice of protective agent may depend on the printer device to be used. The blocking agent may have an unblocking (cut-off) temperature that is less than the printer operating temperature, and the selection of the blocking agent may depend not only on the printer operating temperature, but also on the duration of time (residence time) that the ink or toner is exposed to the operating temperature. Examples of electrophilic reactive components so protected include internally (also referred to as non-blocking agents) and externally blocked polyisocyanates. The internally blocked polyisocyanate was the product isophorone diisocyanate (IPDI) from Bayer, Crelan VP LS 2147. Common examples of external blocking agents include phenols and substituted phenols, alcohols and substituted alcohols, thiols, lactams, thiol amides (mercaptam), primary and secondary acid amides, imides, aromatic and aliphatic amines, active methylene compounds, oximes of aldehydes and ketones, and salts of sulfuric acid. An example of an externally blocked polyisocyanate is epsilon-caprolactam blocked vestigon EP B1400 from CreaNova.

In one embodiment, the ink comprises a colorant, a carrier, a humectant, a co-solvent, a surfactant or an emulsifier, and one or both of active hydrogen and a crosslinking reactive compound or ingredient. Additional active hydrogen-containing components and/or cross-linking agents may be stored in another ink reservoir for printing by a separate print head. In an alternative embodiment, all active hydrogen components, such as polyols, are included in the ink, while all cross-linking agents, such as polyisocyanates, are stored separately in another ink.

The colorant used in the ink may be a dye or a pigment, or a combination of these colorants. Suitable dyes include, but are not limited to, pigments, surface modified pigments from chemically grafted, self-dispersed pigments, chemically or physically encapsulated pigments, acid dyes, direct dyes, reactive dyes, basic dyes, solvent dyes, disperse dyes, reactive disperse dyes, sulfur dyes or vat dyes or combinations thereof. Colorants containing hydroxyl, amine, carboxylic acid, or other active hydrogen-containing functional groups that are capable of reacting with the electrophilic crosslinking agent without altering the desired color tone are preferred. More preferred are those containing at least one alkoxy or alkylamino group. Examples of such colorants include disperse red 55, solvent red 117, and disperse blue 3. Other examples are described, for example, in U.S. patent nos. 4749784 and 6159250. These colorants can be used alone or in combination with multiple colorants, which may or may not be the same type, and the remaining toner or ink ingredients to improve application quality. Pigments and dyes may be incorporated into a flush resin system for easier dispersion within the toner system. Examples of flush colorants are Sun Phoblue-Green Shade 15 and Sun Diaryl Yellow AAOT 14(Sun Chemical), and Hostacopy E02-M101 magenta (Clariant). The ink may contain 0-30% colorant. The pigmented ink will preferably contain 4 to 15 wt% colorant.

Disperse colorants, or sublimation colorants, are examples of heat-activated dyes that produce vivid and dark colored images when printed or dyed on certain synthetic materials. When properly activated on synthetic materials, the translucent nature of the colorant allows the incident radiation to partially pass through the printed substrate, while the color is reflected and refracted to produce increased color density and aesthetic color effects. These colorants should not be significantly covered or obscured by opaque colorants, fabric materials, or polymeric materials that significantly interfere with light reflection.

In one embodiment, the reactive ink or toner comprises at least one dispersed or sublimating colorant. Transparent or translucent polymeric materials are also provided, the colorants having an affinity for these polymeric materials. The polymeric material may be provided in an ink. The ink may be printed on the surface of the substrate or on an image printed by the first layer of ink comprising a pigment, which pigment is opaque or translucent. After activation, curing or crosslinking of the reactive ink and the sublimation colorant proceeds simultaneously to produce an intense and vivid color image on the final substrate. When the substrate is a natural fiber material such as cotton, silk, wool, jute, and the like, this combination produces superior image quality, particularly in terms of color intensity, as compared to reactive inks that use colorants with non-sublimating or dispersible dyes. Image fastness is generally improved compared to the use of sublimating colorants alone. Most preferably, one of the reactive ingredients is a reactive polymeric material having an affinity for disperse or sublimation dyes.

Suitable dispersed or sublimed colorants for use in the process of the present invention include anthraquinones, azos, diazos, quinolines,Oxazines, coumarins, xanthenes, benzimidazoles, diphenylamines, and the like. Specific examples of such colorants include, but are not limited to, dispersed yellow 54, dispersed yellow 241, dispersed yellow 243, dispersed orange 1, dispersed orange 3, dispersed orange 11, dispersed orange 155, dispersed red 1, dispersed red 4, dispersed red 11, dispersed red 364, dispersed red 60, dispersed red 91 and 92, dispersed red 368, dispersed blue 3, dispersed blue 14, dispersed blue 26, dispersed blue 35, dispersed blue 56, dispersed blue 60, dispersed blue 72, dispersed blue 79, dispersed blue 87, dispersed blue 165, dispersed blue 183, dispersed blue 359, dispersed violet 17, dispersed violet 33, dispersed violet 63, dispersed green 6, dispersed blue 9, dispersed brown 1, dispersed brown 9, dispersed brown 24-27, dispersed black 1, dispersed black 9, and combinations of these colorants. Those colorants are sometimes described in the Colour Index, Third Edition (1992) as "disperse dyes" and may be suitable as disperse or sublimating colorants in accordance with the present invention. Certain solvent dyes may also be used alone or in combination with a dispersed or sublimed colorant, such as solvent red 155. Preferably, the dispersed or sublimed colorant is free of sulfo and/or carboxyl functional groups and has a molecular weight of no greater than 1000, most preferably no greater than 600.

Polymeric or synthetic materials such as polyesters, aliphatic or aromatic modified polyesters, and linear or branched polyamides and modified polyamides, polyurethane polyurethanes, polycarbonates, and the like, which exhibit an affinity for dispersed or sublimed colorants after a heat activation or sublimation process, may be used. Reactive polymers or synthetic materials of these materials are particularly desirable due to their ability and affinity to crosslink the dispersed or sublimed colorant. The reactive functional groups of these polymeric materials participate in crosslinking reactions with both the reactive colorant, such as reactive dyes, acid dyes, basic dyes, vat dyes, and/or graft reactive pigments, and the functional groups from the final printed substrate. Significantly reduced surface fibrillation is achieved and improved image fastness and durability are obtained. The affinity of the disperse or sublimation dyes for the polymeric material improves color intensity and appearance quality. Examples of such materials include polyester polyols such as polyethylene adipate (PEA), polybutylene adipate, (PTMA), Polycaprolactone (PCL), caprolactone polyester polyols (e.g., CAPA 2043, 2054, 3031, 3022, 3050, 3091, 4101 from Brian-Jones of united Kingdom), polyester polyamines, polyamides, unsaturated polyesters, polymers with amino-or hydroxyamino-functional groups or pendant functional groups, ethylene-vinyl acetate copolymer (EVA) homopolymers or copolymers, reactive polyurethanes, self-crosslinking polyurethanes, hybrid polyurethanes such as acrylic or polyacrylic polyurethanes, acetoacetoxy (AcAc) functionalized polymers or resins such as acetoacetoxyethyl acrylate (AAEA) and acetoacetoxyethyl methacrylate (AAEM). Water soluble/water dilutable, and solvent soluble, or solvent free plasticizer polymeric materials may be used. Solutions, emulsions or micro/macro emulsions, natural or synthetic polymeric latexes, colloids or sol-gel systems comprising these polymers may also be used in the desired inks or toners. Preferably, the polymer or resin material having affinity for the dispersed or sublimed colorant has a molecular weight of 3,000-500,000 and a glass transition temperature (Tg) of not higher than 220 ℃. Most preferably, a molecular weight of 5,000-100,000 and a glass transition temperature (Tg) of not higher than 60 ℃ may be used.

The colorant may be dispersed or sublimed by heat or radiation activation. Depending on the desired activation or sublimation energy level of the colorant, the ink may be activated at temperatures of 100-. However, the preconditioned polymer/colorant inks can significantly reduce the energy level for activation. In such preconditioned inks, the dispersed or sublimed colorant is activated and bonded to the polymer in the same ink prior to or during the printing process, allowing activation at much lower energy levels, or even at ambient temperature conditions. Lower curing or crosslinking temperatures may be advantageous for thermal energy efficiency and may also reduce the loss of the final printed substrate due to exposure to heat and/or radiation. When two layers of ink are used, it is preferred that the inks cure and crosslink at substantially the same rate and efficiency to minimize print defects.

The ink may comprise a binder component. Typically, the ink binder is a "tack" that holds the ink to the substrate. The binder may be a single resin or a complex combination of resins, plasticizers, and other additives. The binder influences the viscosity of the system and promotes droplet formation. Binders are also used to adhere the colorant to the surface of the substrate, to control the gloss of the colorant, to control the print definition of the colorant and to determine the alkali solubility of the ink, among other purposes. The binder is preferably film-forming, amorphous, low-odor, colorless or light-colored, transparent. The binder is either soluble in the carrier system or forms a stable emulsion or colloid in the carrier system, wherein surfactants, emulsifiers, humectants and/or co-solvents may be used in the ink. Structured or random polymers may be selected for use as ink binders. The structured polymer has a block, branched or grafted structure. Particularly preferred are active hydrogen functional binders that can participate in the binding/crosslinking of reactive inks. These reactive groups may be protected by capping agents.

The aqueous ink formulation comprises water as the majority of the ink vehicle. Thus, the binders used in aqueous ink formulations should be water-soluble, dispersible or emulsifiable polymers and copolymers. Examples of such binders include phenolics; acrylic resins such as poly (meth) acrylic acid and salts, polyacrylamide, polystyrene acrylate; vinyl resins such as polyvinyl alcohol, polyvinyl acetate and polyvinyl butyral; polyoxyalkylenes such as polyoxyethylene and polyethylene glycol; a polyamide; polyamines such as polyvinylpyridine, polyvinylpyrrolidone, polyvinylamine, and polyethyleneimine; cellulose derivatives such as nitrocellulose, ethyl cellulose, hydroxyethyl cellulose ethyl ether, cellulose acetate butyrate, cellulose acetate propionate and sodium carboxymethyl cellulose.

Other aqueous ink additives such as water-soluble humectants, co-solvents, humectants, emulsifiers, solubilizers, charging agents, and dispersants may be used to help the hydrophobic component produce a stable emulsion or colloid in an ink suitable for any of the foregoing printing systems. The co-solvent may serve several functions. They may act as chain extenders for participating in crosslinking and bonding reactions. The co-solvent may have two or more functional groups containing active hydrogen such as diols, triols, polyols, diamines and polyamines. They act as humectants, i.e., they help minimize water evaporation and prevent the dye/pigment from crystallizing inside the ink jet nozzle. The co-solvent may further help to control the viscosity and surface tension of the ink, two very important parameters. Preferred cosolvents for use in the present invention include, but are not limited to, N-methylpyrrolidone and glycols, especially glycols such as LEG-1 and LEG-7 (both available from Lipo Chemicals), diethylene glycol, propylene glycol, and the like, as well as ethers, especially monoalkyl ethers, of such glycols. Straight chain ethers may be more effective viscosity reducers than branched chain isomers, and their efficiency may increase with increasing number of carbon atoms in the alkoxy group.

The proper selection of co-solvents can improve the solubility of certain colorants. In addition, the use of co-solvents with boiling temperatures lower than water can also help improve the stability of emulsion ink systems for thermal or bubble jet ink systems. Such co-solvents enable rapid formation of vaporized foam, thereby preventing emulsion particles from breaking due to heat from the heating element, while helping to inhibit deblocking of blocked components in the ink due to exposure to heat during the printing process. Examples of such co-solvents include 1-methoxy-2-propanol, isopropanol, and isobutyl vinyl ether.

The wetting agent may include such compounds as fatty acid alkanolamides, oxyethylene adducts derived from fatty alcohols or fatty amines. Other surface tension modifiers and/or interfacial modifiers include, but are not limited to, di-, tri-ethanol amine, amine oxide, sulfonated alkyl/fatty esters, aromatic/alkyl phosphates.

Typical water-based dye/pigment dispersants include such compounds as lignosulfonates, fatty alcohol polyglycol ethers and aromatic sulfonic acids, for example naphthalenesulfonic acid. Some dispersants are polymeric acids or bases that act as electrolytes in aqueous solutions in the presence of suitable counterions. Such polyelectrolytes may provide electrostatic as well as steric stabilization of the dispersed particles in the emulsion. In addition, they provide inks with charging characteristics if required by the printer application. Examples of the polyacid include polysaccharides such as alginic acid and sodium carboxymethyl cellulose; polyacrylates such as polyacrylic acid, styrene-acrylate copolymers; polysulfonates such as polyvinylsulfonic acid, styrene-sulfonate copolymers; polyphosphates such as polymetaphosphoric acid; polydiacid (or hydrolyzed anhydride), such as styrene-maleic acid copolymer; a polytriatomic acid such as an acrylic acid-maleic acid copolymer. Examples of the polybases include polyamines such as polyvinylamine, polyethyleneimine, poly (4-vinylpyridine); polyquaternary ammonium salts such as poly (4-vinyl-N-dodecylpyridinium). Amphoteric polyelectrolytes may be obtained by copolymerizing suitable acidic monomers and basic monomers, for example, methacrylic acid and vinylpyridine.

The aqueous ink further comprises a pH modifier; anti-foaming chemicals such as silicone oil emulsions; a melt control agent; a preservative; a fungicide; antifreezes, such as ethylene glycol, propylene glycol, glycerol or sorbitol; antioxidants and ultraviolet light stabilizers.

The aqueous ink additives may contain reactive functional groups to improve the water resistance of the final image, as such additives are hydrophilic substances. Preferred additives are surfactants containing active hydrogen functional groups and may be protected by capping agents.

For anhydrous ink formulations, the carrier may be based on organic solvents, such as hydrocarbon, alcohol, glycol ether, glycol ester, ketone, or ester solvents. Alternatively, the carrier may be based on natural or synthetic drying or non-drying oils. Preferably, in order to increase reactivity and reduce percent solids, a reactive support having nucleophilic functional groups containing active hydrogen will be used. The binders used in such inks must be soluble or emulsifiable in these vehicles. The ink binder may include a resin, a plasticizer, and a wax. Typical resins include phenolic resins, rosin-modified phenolic resins, alkyd resins, hydrocarbon resins, polystyrene resins and copolymers, terpene resins, silicone resins, alkylated urea-formaldehyde resins, alkylated melamine-formaldehyde resins, polyamide and polyimide resins, chlorinated and cyclized rubbers, vinyl resins, ketone resins, acrylic resins, epoxy resins, polyurethane resins, and cellulose derivative resins. Other additives include surfactants, dispersants, antioxidants, light stabilizers, and drying oil catalysts.

For phase change or hot melt ink formulations, a hot melt carrier is used with a combination of hot melt resin, wax or waxy material, tackifier and plasticizer. These materials are in solid form at room temperature but become liquid at the temperatures at which the printer operates (typically 50-150 ℃). Examples of phase change ink carriers include paraffins, microcrystalline waxes, polyethylene waxes, ester waxes, fatty acids, fatty alcohols, fatty amides (typically mono-and tetra-amide resins), sulfonamide materials, resinous materials made from different natural sources (tall oil rosins and rosin esters), and many synthetic resins, oligomers, polymers, and copolymers. The preferred tetra-amide resin is dimer acid based tetra-amide, which is the reaction product of dimer acid, ethylene diamine and stearic acid. Preferred tackifier resins are glycerol esters of hydrogenated rosin acids. Other additives may include binders, viscosity modifiers, light stabilizers, antioxidants, and the like.

Viscosity control of the liquid ink allows the ink to be printed by an ink jet printing apparatus. For a typical ink jet printer, the viscosity value of the ink may be 1 to 50cps, preferably 3 to 20 cps. Too viscous an ink may result in printing difficulties, poor drop size or shape formation and control, and/or damaged printing orifices.

Surfactants can be used in wetting, emulsifying, solubilizing, ink droplet formation and surface energy control or modification processes. Surfactants used to produce oil-in-water emulsions can include anionic, cationic, nonionic, and amphoteric surfactants having various molecular weight values. The surfactant used in the non-aqueous emulsion ink system is preferably a nonionic surfactant. Depending on the specific HLB (hydrophilic lipophilic balance) value, some surfactants may also be referred to as emulsifiers. High HLB surfactants are typically used to emulsify oil-in-water or water-containing systems, while low HLB surfactants may be typically used to produce water-in-oil or water-free emulsion systems. Reactive surfactants may also be used. Reactive surfactants include hydroxyl, carboxyl, amine, amide terminated copolymer surfactants.

When the surfactant/emulsifier concentration in the liquid carrier exceeds its Critical Micelle Concentration (CMC), the molecules of the surfactant/emulsifier begin to aggregate. Aggregation of the surfactant/emulsifier together with the other ingredients forms micelles or reverse micelles, which have a typical structure in which insoluble ingredient particles or aggregates are surrounded by surfactant/emulsifier molecule layers, depending on whether the main carrier phase is aqueous or non-aqueous. A homogeneous but heterogeneous system is thus created in which small but isolated droplets carry the colorant, binder, miscible or immiscible co-solvents and/or humectants, additives, etc. within the micellar structure and are suspended in this bulk carrier phase to prevent further aggregation or phase separation. These micelle particle sizes are small enough to produce a free flowing liquid suitable for ink jet printing without clogging the printing machinery, and to protect the ingredients, especially the heat sensitive material inside the micelle particles, which are in direct contact with each other and/or with the heating element in the printing machinery, such as thermal or bubble jet printing. The insoluble, immiscible components used for this application can thus be stabilized at useful concentrations.

To produce stable emulsion, micro/macro emulsion, colloidal or sol-gel ink systems, surfactants/emulsifiers may be used. Multiple surfactants/emulsifiers may also be used in combination to further improve protection, stability, flow characteristics, and printing performance, provided such materials do not have any negative impact on the reactive ingredients during storage and image creation. In addition, depending on the CMC, HLB, and/or other characteristics of the surfactant/emulsifier, different concentrations may be used to obtain the best performance of the ink system corresponding to a particular printing machine.

Examples of surfactants and emulsifiers include alkylaryl polyether alcohol nonionic surfactants such as the Triton X series (octylphenoxy-polyethoxyethanol); alkylamine ethoxylate nonionic surfactants such as the Triton FW series, tritiated CF-10 and tergitol (Union Carbide Chemicals); polysorbate products such as Tween (ICI Chemicals and polymers); polyalkylene and polyalkylene-modified surfactants such as Silwet surfactants (polydimethylsiloxane copolymers) and CoatOSil surfactants available from OSISPECIATILES; alcohol alkoxylate nonionic surfactants such as Renex, BRIJ, and Ukanil; sorbitan ester products such as Span and Arlacel; alkoxylated ester/PEG products, such as Tween, Atlas, Myrj and Cirrasol surfactants from ICI Chemicals and Polymers; unsaturated alcohol products such as surfynol series surfactants from air products co, alkyl phosphate ester surfactant products such as amyl acid phosphate, Chemphos TR-421; alkylamine oxides such as the Chemoxide series from chemron corporation; anionic sarcosinate surfactants such as the Hamposyl series from Hampshire Chemical corporation; glyceride or polyglycol ester nonionic surfactants such as the Hodag series from Calgene Chemical, Alphenate (Henkel-Nopco), Solegal W (Hoechst AG), Emultex (Auschem SpA); and polyglycol ether surfactants such as Newkalgen available from Takemoto Oil and fat.

In addition to producing stable emulsion or colloidal ink systems, surfactants are also used for surface energy or surface tension control. In the aqueous or non-aqueous case, the surface tension of the final ink should be 20dyne/cm to 55dyne/cm, preferably 35dyne/cm to 45 dyne/cm.

The final transfer substrate may comprise plastic, metal, wood, glass, ceramic, paper or textile material. Preferred textile materials include such materials as cotton, cellulose diacetate, rayon, wool, silk and polyamides such as nylon 6, nylon 66 or nylon 12. The substrate must be able to withstand the heat transfer temperature without deforming, melting or degrading. The final substrate may either comprise a compound having active hydrogen-containing groups or have a surface coating comprising such groups. Chemical grafting is accomplished via copolymerization between the ink layer components and the final substrate material, resulting in excellent stability and durability.

A thermally expandable ink may be produced wherein the ink and/or medium comprises an expansion agent. Simultaneous swelling and crosslinking produces a three-dimensional image that is permanently bonded to the substrate. The height of the image depends on the concentration of the swelling agent, the temperature and pressure applied during thermal transfer.

Preferred swelling agents include those that release gaseous products that cause the ink to swell when heated. Such expanding agents (known as chemical blowing agents) include organic expanding agents such as azo compounds including azobisisobutyronitrile, azodicarbonamide, and diazoaminobenzene, nitroso compounds such as N, N ' -dinitrosopentamethylenetetramine, N ' -dinitroso-N, N ' -dimethyl terephthalamide, sulfonyl hydrazides such as benzenesulfonyl hydrazide, p-toluenesulfonyl azide, hydrazolcabonimide, acetone-p-sulfonylhydrazone; and inorganic swelling agents such as sodium hydrogen carbonate, ammonium carbonate and ammonium hydrogen carbonate. Such swelling agents may be dissolved or dispersed in the pigmented ink, in a separate ink reservoir, coated on an intermediate medium, or a combination of the above.

Thermally expandable inks may alternatively be prepared by using a volatile hydrocarbon encapsulated in microspheres which rupture upon heating. The released gaseous products swell the ink. These thermally expandable microcapsules are composed of a hydrocarbon disposed within a thermoplastic resin wall, which is volatile at low temperatures. Examples of hydrocarbons suitable for use in the practice of the present invention are methyl chloride, methyl bromide, trichloroethylene, dichloroethane, n-butane, n-heptane, n-propane, n-hexane, n-pentane, isobutane, isopentane, neopentane, petroleum ethers and fluorine-containing aliphatic hydrocarbons such as Freon, or mixtures thereof.

Materials suitable for forming the walls of the heat-expandable microcapsules include polymers of vinylidene chloride, acrylonitrile, styrene, polycarbonate, methyl methacrylate, ethyl acrylate, and vinyl acetate, copolymers of these monomers, and mixtures of the polymers and copolymers. A crosslinking agent may be used as appropriate.

The microcapsules may be dispersed or emulsified in the pigmented ink, in a separate ink reservoir, coated on an intermediate medium, or a combination of the above. The diameter of the thermally expanded microcapsules is 0.01 to 20 microns, preferably 0.1 to 5 microns, more preferably 0.1 to 1 micron.

It may be advantageous to include a catalyst to catalyze the crosslinking reaction and to help control the crosslinking or bonding reaction of the image to the final substrate. Examples of the catalyst include tertiary amines such as methylene amine, triethylene diamine, hexahydro-N, N '-dimethylaniline, tribenzylamine, N-methyl-piperidine, and N, N' -dimethylpiperazine; heterocyclic nitrides, e.g. 1, 5-diazobicyclo [4.3.0]Non-5-ene and diazobicyclo [2.2.2]Octane; alkali or alkaline earth metal hydroxides; heavy metal ions, such as iron (III), manganese (III), vanadium (V) or metal salts, such as lead oleate, lead 2-ethylhexanoate, zinc (II) octanoate, lead and cobalt naphthenates, zinc (II) ethylhexanoate, dibutyltin dilaurate, dibutyltin diacetate, and also bismuth, antimony and arsenic compounds, for example tributylarsenic, triethylstilbene oxide or phenyldichlorostilbene. Preferably, the present invention uses a blocked catalyst that can catalyze the crosslinking and bonding chemistry only under the desired conditions to be achieved. Examples of such blocked catalysts include, but are not limited to, Nacure2547、Nacure4575 and Nacure4167(King Industries). The use of catalysts is highly desirable when the final activation conditions are severe and the final substrate is sensitive to such severe conditions. When the crosslinking or bonding reaction involves a protein-containing material, such as wool, silk or Soy Protein Fiber (SPF), biological or enzymatic catalysis may also be used.

The printing process produces a permanent image on natural or synthetic fibrous materials in which the ink remains in unreacted form during the printing process, but which will crosslink and bond with the substrate after activation of the reactive component with energy, including heat, during the fixing process, or during the transfer process. In one embodiment, the ink comprises: a compound having a functional group reactive with active hydrogen such as isocyanate, and a compound having a functional group containing active hydrogen or a functional group capable of being converted into an active hydrogen-containing group.

The ink may contain a reactive polymer or resin material having functional groups to improve crosslinking reactivity with the final substrate, and to improve compatibility of the colorant to achieve excellent color strength and fastness. The inks may also be comprised of pigments (organic or inorganic) and/or dyes, such as medium to high energy sublimation disperse dyes, dye diffusion heat sensitive dyes, or other dyes, any of which may be referred to herein as colorants. Without delivering the ink material to the non-imaged areas, the present invention can provide an imaging device on fibrous materials that do not have a "hand" in the non-imaged areas thereby substantially maintaining the original characteristics of the substrate and improving the final image quality.

The present invention provides a process for imaging a substrate having commercially acceptable color vividness and color fastness. One embodiment of the ink (which may be a colorless ink) includes a reactive component, or the ink may include at least one transparent or translucent binder material having an affinity for the dispersed or sublimating colorant, and at least one dispersed or sublimating colorant to cover the printed image. After drying or activation, the additional coverage of the ink reduces fibrillation of the final substrate, increases the chromatographic reflection and diffraction of the printed image from all viewing angles, and improves image permanence and color fastness.

Claims (24)

1. A digital printing method comprising the steps of:

a. preparing a reactive ink comprising a first reactive agent and a second reactive agent, wherein the first reactive agent is reactive with the second reactive agent;

b. supplying the reactive ink to a digital printer;

c. digitally printing the reactive ink on a substrate;

d. digitally printing on said substrate an ink comprising a heat-activated dye, wherein said heat-activated dye has an affinity for a polymer selected from the group consisting of polyesters, aliphatic or aromatic modified polyesters, and linear or branched polyamides, polyurethanes, polyester polyurethanes, polycarbonates upon activation thereof; and

e. the first reactive agent is then reacted with the second reactive agent to bond the reactive ink to the substrate, and the heat activated dye is heat activated to fix the heat activated dye to a polymer present on the substrate provided by the reaction of the first and second reactive agents.

2. The digital printing method as claimed in claim 1, wherein said reactive ink comprises a heat activated dye.

3. The digital printing method of claim 1, wherein the reactive ink further comprises a pigment.

4. The digital printing method as claimed in claim 1, wherein said ink comprising heat activated dye is printed on said reactive ink after printing said reactive ink.

5. The digital printing method as claimed in claim 1, wherein said ink comprising a heat-activated dye comprises a polymer.

6. The digital printing method of claim 1, wherein the first reactive agent comprises a functional group that reacts with active hydrogen and the second reactive agent comprises active hydrogen.

7. The digital printing method as claimed in claim 1, wherein said heat activated dye is a disperse dye.

8. The digital printing method as claimed in claim 1, wherein said heat activated dye is a sublimation dye.

9. A digital printing method comprising the steps of:

a. preparing a reactive ink comprising a first reactive agent, a second reactive agent and a heat activated dye, wherein the heat activated dye has an affinity for a polymer selected from the group consisting of polyesters, aliphatic or aromatic modified polyesters, and linear or branched polyamides, polyurethanes, polyester polyurethanes, polycarbonates upon activation thereof, and wherein the first reactive agent is reactive with the second reactive agent;

b. supplying the reactive ink to a digital printer;

c. digitally printing the reactive ink on a substrate; and

d. the first reactive agent is then reacted with the second reactive agent to bond the reactive ink to the substrate, and the heat activated dye is heat activated to fix the heat activated dye to a polymer present on the substrate provided by the reaction of the first and second reactive agents.

10. The digital printing method of claim 9, wherein the reactive ink further comprises a pigment.

11. The digital printing method as claimed in claim 9, wherein a second ink comprising a heat activated dye is printed on the reactive ink after printing the reactive ink.

12. The digital printing method of claim 9, wherein the first reactive agent comprises a functional group that reacts with active hydrogen and the second reactive agent comprises active hydrogen.

13. The digital printing method as claimed in claim 9, wherein said heat activated dye is a disperse dye.

14. The digital printing method as claimed in claim 9, wherein said heat activated dye is a sublimation dye.

15. A digital printing method comprising the steps of:

preparing a first ink comprising functional groups reactive with active hydrogen;

preparing a second ink comprising active hydrogen;

supplying said first ink to a digital printer;

supplying said second ink to a digital printer;

printing the first ink on a substrate;

printing the second ink on the substrate;

printing a heat-activated dye on said substrate, wherein said heat-activated dye has an affinity for a polymer selected from the group consisting of polyesters, aliphatic or aromatic modified polyesters, and linear or branched polyamides, polyurethanes, polyester polyurethanes, polycarbonates upon activation thereof; and

the active hydrogen-reactive functional group is then reacted with the active hydrogen to bond the first ink and the second ink to the substrate, and heat is applied to the heat activated dye, wherein the first ink, the second ink, and the heat activated dye form an image on the substrate, and the heat activated dye bonds to a polymer provided by the reaction of the first ink and the second ink.

16. The digital printing method of claim 15, wherein the first ink further comprises a pigment.

17. The digital printing method as claimed in claim 15, wherein said heat activated dye is a disperse dye.

18. The digital printing method as claimed in claim 15, wherein said heat activated dye is a sublimation dye.

19. A digital printing method comprising the steps of:

a. preparing a reactive ink comprising functional groups reactive with active hydrogen;

b. digitally printing the reactive ink on a substrate comprising active hydrogen;

c. digitally printing on said substrate an ink comprising a heat-activated dye, wherein said heat-activated dye has an affinity for a polymer selected from the group consisting of polyesters, aliphatic or aromatic modified polyesters, and linear or branched polyamides, polyurethanes, polyester polyurethanes, polycarbonates upon activation thereof; and

d. the reactive ink is then immobilized on the substrate by reacting the ink of step C with the substrate, and the heat-activated dye is heat-activated to bind the heat-activated dye to the polymer provided by the reaction of the ink of step C and the substrate.

20. The digital printing method of claim 19, wherein the reactive ink comprises a pigment.

21. The digital printing method as claimed in claim 19, wherein said ink comprising a heat-activated dye comprises active hydrogen.

22. The digital printing method of claim 19, wherein the substrate comprises cotton.

23. The digital printing method as claimed in claim 19, wherein said heat activated dye is a disperse dye.

24. The digital printing method as claimed in claim 19, wherein said heat activated dye is a sublimation dye.