Ink composition, ink set, method for producing an ink composition, printing method, and printing press

Abstract

The present invention relates to a radiation curable gelling ink composition. The present invention further relates to an ink set and a method of preparing a radiation curable gelling ink composition. Furthermore, the present invention relates to a printing method and a printing press.

Description

[0001] This invention relates to a radiation-curable gel ink composition. The invention further relates to an ink composition and a method for preparing the radiation-curable gel ink composition. Additionally, this invention relates to printing methods and printing presses. Background of the Invention Methods for applying an image onto a recording medium using a radiation-curable ink composition are known in the art. Typically, such methods involve applying a radiation-curable ink to the recording medium, for example, by ejecting droplets of ink using an inkjet printer. After the ink has been applied to the recording medium, the ink is irradiated with a suitable type of radiation to harden it. A curing unit configured to emit a suitable type of radiation, such as ultraviolet radiation, during operation can be used to irradiate the ink.

[0003] Radiation-curable gel ink compositions are a special class of radiation-curable ink compositions. These inks are fluid at elevated temperatures and gel at lower temperatures. In the gel state, the ink has a high viscosity, which prevents it from flowing. Radiation-curable gel ink compositions are typically sprayed at elevated temperatures and rapidly cooled after deposition onto the recording medium to form an image. Because the ink viscosity increases after deposition onto the recording medium, the ink does not need to cure immediately after deposition. Instead, there can be a time interval between ink application and curing, such as a time interval in the range of 10 to 100 seconds. Alternatively, the ink can be fixed (i.e., partially cured) shortly after application to the recording medium and then fully cured, such as after a time interval in the range of 10 to 100 seconds.

[0004] One known problem with printing using radiation-curable gel inks is that the cured ink layer may not adhere well to the recording medium.

[0005] Therefore, there is a need to apply images with improved adhesion to recording media. Furthermore, there is a need to apply images with improved adhesion to a variety of recording media.

[0006] Therefore, one object of the present invention is to provide an ink composition that provides an image with improved adhesion when printed onto a recording medium.

[0007] Another object of the present invention is to provide a printing method and a printing press suitable for performing the method. Invention Overview The present invention achieves its objective through a radiation-curable gelling ink composition comprising a radiation-curable matrix and one or more gelling agents. The radiation-curable matrix is ​​composed of one or more radiation-curable components and one or more inert resins. The radiation-curable matrix has a double bond density (DBD) and an average functionality (average F). The double bond density (DBD) is defined as follows: And the average functionality is defined as: The DBD is higher than 3, and the average functionality ranges from 0.9 to 1.25.

[0009] From the above definition of double bond density (DBD), the unit of DBD is "moles per gram". Furthermore, from the definition of average functionality (average F), average functionality is a dimensionless number.

[0010] This radiation-curable gelling ink composition comprises a radiation-curable matrix and a residual ink composition. The radiation-curable matrix comprises one or more radiation-curable components and one or more inert resins. The residual ink composition may not contain any radiation-curable components. Furthermore, the residual ink composition may not contain any inert resin. The residual ink composition may contain, for example, one or more photoinitiators, one or more gelling agents, one or more inhibitors, one or more colorants, and / or one or more dispersants.

[0011] Based on the total weight of the radiation-curable gel ink composition, the radiation-curable matrix and the remaining ink composition together exist at 100% by weight.

[0012] Radiation-curable ink compositions are ink compositions that can be cured using a suitable type of radiation. Ultraviolet radiation is an example of a suitable type of radiation.

[0013] The radiation-curable gel ink composition may contain a radiation-curable matrix.

[0014] In addition to the components contained in the radiation-curable matrix, the radiation-curable gel ink composition may also contain additional components, such as one or more colorants, one or more dispersants, one or more solvents and / or one or more co-solvents, one or more photoinitiators, one or more sensitizers and / or one or more co-initiators, one or more inhibitors and / or one or more surfactants. These additional components may form the remaining ink composition. The colorant may be a dye or pigment. Preferably, the colorant is a pigment or a combination of more than one pigment. The one or more solvents and the one or more co-solvents preferably do not contain functional groups capable of polymerization when activated by ultraviolet radiation.

[0015] Radiation-curable substrates may contain one or more radiation-curable components.

[0016] The one or more radiation-curable components may contain radiation-curable monomers and / or radiation-curable oligomers.

[0017] The monomer and oligomer can be monofunctional (i.e., one polymerizable group per molecule), difunctional (i.e., two polymerizable groups per molecule), trifunctional (i.e., three polymerizable groups per molecule), tetrafunctional (i.e., four polymerizable groups per molecule), or polyfunctional (i.e., five or more polymerizable groups per molecule).

[0018] Examples of radiation-curable monomers are (meth)acrylates, epoxides, vinyl resins, vinyl ethers, vinyl esters, vinyl ether acrylates, allyl ethers, allyl esters, acrylamide, methacrylamide, styrene, maleate, fumarate, and itaconic acid esters.

[0019] Examples of radiation-curable oligomers include urethane acrylate oligomers, polyester oligomers, amine-functionalized oligomers, polyether oligomers, polyamide oligomers, acrylate oligomers, and epoxy-based materials such as bisphenol A epoxy acrylates and epoxy acrylates.

[0020] Preferably, the one or more radiation-curable components may comprise one or more acrylates. Preferably, the one or more radiation-curable components may comprise monofunctional and non-monofunctional components, such as difunctional, trifunctional, tetrafunctional, and multifunctional components.

[0021] In addition, the radiation-curable matrix may contain at least one amine acrylate. Amine acrylates are also known as acrylated amines. Amine acrylates can improve the surface curing of ink layers when exposed to radiation, such as ultraviolet radiation.

[0022] The radiation-curable matrix may further contain one or more resins.

[0023] This resin is an inert resin, meaning it does not contain polymerizable groups. Examples of resins include polyurethane resins, polyester resins, acrylic resins, polystyrene resins, acrylic copolymer resins such as acrylic-styrene resins, polyolefin resins such as polyethylene resins, polypropylene resins, ethylene-propylene copolymer resins, MMA copolymers, polyesteramides, benzoic acid esters, polyvinyl acetate, polybutyl acetate, ketone resins, cellulose esters, (modified) rosin resins, polyvinyl butyral resins, vinyl chloride resins, ketone-aldehyde condensation resins, and polyol resins such as polyester polyol resins.

[0024] The addition of inert resin can improve the properties of the cured ink layer.

[0025] In one embodiment, the one or more inert resins may be selected from acrylic resins, styrene resins, and / or styrene-acrylic resins.

[0026] Radiation-curable substrates may consist of one or more radiation-curable components and one or more inert resins.

[0027] Radiation-curable gelling ink compositions may contain one or more gelling agents. A gelling agent is also known as a gelling aid, gelator, gelling agent, or thickener.

[0028] The presence of one or more gelling agents can cause an increase in the viscosity of the inkjet ink composition upon cooling. This increase in viscosity should be sufficient to adequately control droplet spreading.

[0029] Examples of gelling agents used in gelled radiation-curable inkjet ink compositions are waxes, such as paraffin wax, microcrystalline wax, polyethylene wax, polypropylene wax, curable waxes, and natural waxes, such as animal-based or plant-based waxes; fatty acids, fatty alcohols, ketones, fatty acid esters, such as fatty acid esters of pentaerythritol and / or fatty acid esters of dipentaerythritol; and fatty acid amides. Because gelled inks reduce ink spread on the recording medium due to their gelling properties, it may not be necessary to cure the ink droplets immediately after they are applied to the recording medium. The droplets can remain on the recording medium in an uncured state without bleeding. The gelling agent may be present in an amount of 0.1% to 15% by weight based on the total weight of the ink composition, preferably 0.2% to 10% by weight based on the total weight of the ink composition, and more preferably 0.3% to 5% by weight based on the total weight of the ink composition.

[0030] Radiation-curable gel ink compositions may further comprise one or more photoinitiators. Photoinitiators can be classified into Norrish Type I and Norrish Type II photoinitiators. Each of these types of photoinitiators contains several subcategories of photoinitiators.

[0031] Examples of photoinitiators belonging to the Norrish Type I photoinitiator category include benzoyl ketal, benzoin ether, acylphosphine oxide, α,α-dialkoxyacetophenone, α-hydroxyalkylphenyl ketone, α-aminoalkylphenyl ketone, acylphosphine oxide, acylphosphine sulfide, α-haloketone, α-halosulfone, phenylglyoxylate, peroxide, O-acylα-oxime ketone, acylphosphonate, S-thiobenzoate, azo compounds, triazine, and diimidazole. Examples of photoinitiators belonging to the Norrish Type II photoinitiator category include xanthones, thioxanone, benzophenone, 1,2-dione, α-coumarinone, phenylglyoxylate, and anthraquinone.

[0032] Optionally, the radiation-curable matrix may comprise a combination of non-polymerizable, polymerizable, and / or polymerizable photoinitiators. The one or more photoinitiators may be present in an amount from 0.2% to 15% by weight based on the total weight of the ink composition. Preferably, the one or more photoinitiators may be present in an amount from 2.0% to 12% by weight based on the total weight of the ink composition, such as from 5.0% to 10% by weight based on the total weight of the ink composition.

[0033] The radiation-curable gel ink composition may further comprise one or more sensitizers and / or one or more co-initiators. Co-initiators are also known as synergists. Examples of co-initiators suitable for radiation-curable ink compositions are known in the art, including amine synergists. Amine synergists can be monomeric, dimeric, trimeric, oligomeric, or polymeric. Examples of monomeric amine synergists include ethyl 4-dimethylaminobenzoate and 2-ethylhexyl 4-dimethylaminobenzoate. Examples of dimeric amine synergists include Omnipol ASA, Jiuri cure A151, Speedcure 7040, and Esacure A198. The one or more co-initiators may be present in an amount of 0.2% to 10% by weight based on the total weight of the ink composition. Preferably, the one or more co-initiators may be present in an amount of 0.5% to 7% by weight based on the total weight of the ink composition, such as 0.8% to 5% by weight based on the total weight of the ink composition.

[0034] The radiation-curable gelling ink composition may further contain one or more inhibitors. Inhibitors are also known as stabilizers. The presence of the one or more inhibitors can prevent unwanted polymerization reactions during ink storage. The presence of the one or more inhibitors can increase the shelf life of the ink.

[0035] Several types of inhibitors are known, including but not limited to nitryl-based inhibitors such as IrgastabUV10, OHTEMPO, and TEMPO; and phenolic inhibitors such as hydroquinone, butylated hydroxytoluene, 4-methoxyphenol (MEHQ), and 2,6-di-tert-butyl-N,N-dimethylamino-p-cresol.

[0036] The one or more inhibitors may be present in an amount of 0.005% to 2% by weight based on the total weight of the ink composition. Preferably, the one or more inhibitors may be present in an amount of 0.1% to 1% by weight based on the total weight of the ink composition, such as 0.2% to 0.5% by weight based on the total weight of the ink composition.

[0037] The radiation-curable gel ink composition may further comprise one or more surfactants. The presence of one or more surfactants can reduce the surface tension of the ink composition to improve its flowability. Suitable surfactants for radiation-curable ink compositions are known in the art.

[0038] In one embodiment, one or more of the surfactants may contain reactive groups, such as acrylate functional groups. The surfactants may be present in an amount of 0.1% to 3% by weight based on the total weight of the ink composition. Preferably, the surfactants may be present in an amount of 0.4% to 2% by weight based on the total weight of the ink composition, such as 0.5% to 1% by weight based on the total weight of the ink composition.

[0039] The radiation-curable gelled ink composition, particularly the residual ink composition, may contain additional components. These additional components may include one or more solvents, one or more cosolvents, one or more colorants, one or more dispersants, one or more antimicrobial components, and / or one or more antifungal components.

[0040] Preferably, the ink composition is an inkjet ink composition, i.e., an ink composition suitable for jetting using an inkjet printhead.

[0041] The radiation-curable matrix of the radiation-curable gel ink composition according to the present invention has a double bond density (DBD), which is defined as: The DBD is higher than 3.

[0042] the term f i This refers to the functionality of an individual component in a radiation-curable matrix; term (wt%) iThis refers to the percentage by weight of a single component relative to the total weight of the radiation-curable gel ink composition; the term (m) w ) i This refers to the molecular weight of a single component in a radiation-curable matrix. The functionality of a component refers to the number of reactive groups. In this case, reactive groups can be groups capable of undergoing polymerization. A monofunctional monomer can have a functionality of 1; a difunctional monomer can have a functionality of 2; a trifunctional monomer can have a functionality of 3, and so on.

[0043] The radiation-curable matrix comprises a first, second, third, ..., and nth component. For each of these components, the product " f i *( ( wt%) i / ( m w ) i The product of all components of the radiation-curable matrix is ​​added together and the sum is divided by 100 to obtain the DBD. In the radiation-curable gel ink composition according to the invention, the DBD is greater than 3. Preferably, the DBD is greater than 3.25, more preferably greater than 3.5, for example greater than 3.75, for example greater than 4.

[0044] The radiation-curable matrix of the radiation-curable gel ink composition according to the present invention has an average functionality (average F), wherein the average functionality is defined as: The average functionality ranges from 0.9 to 1.25.

[0045] For each component in the radiation-curable matrix, calculate the product " f i *( ( wt%) i / ( m w ) i )) * 1000". Add the products of all components of the radiation-curable matrix to form the numerator of the above fraction. Furthermore, for each component in the radiation-curable matrix, calculate the product "". ( ( wt%) i / ( m w ) i)) * 1000”. Add the products of all components of the radiation-curable matrix, and the resulting sum forms the denominator of the above fraction. Divide the numerator by the denominator to obtain the average functionality of the radiation-curable matrix. In the radiation-curable gel ink composition according to the invention, the average F is in the range of 0.9 to 1.25.

[0046] Surprisingly, it has been found that radiation-curable gel ink compositions comprising one or more resins and a radiation-curable matrix having a double bond density greater than 3 and an average functionality in the range of 0.9 to 1.25 can provide images with good adhesion on a variety of recording media. In one embodiment, the average F is in the range of 1.0 to 1.2, for example 1.01 to 1.15, for example 1.05 to 1.10.

[0047] In one embodiment, the one or more resins may be present in an amount of 2% to 30% by weight based on the total weight of the radiation-curable gel ink composition.

[0048] Preferably, the resin may be present in an amount of 5% to 25% by weight based on the total weight of the radiation-curable gel ink composition, more preferably 7% to 20% by weight based on the total weight of the radiation-curable gel ink composition, for example, 8% to 15% by weight based on the total weight of the radiation-curable gel ink composition.

[0049] When the resin is present in an amount of less than 2% by weight based on the total weight of the radiation-curable gel ink composition, the ink may not exhibit good adhesion on a variety of substrates. When the resin is present in an amount of more than 30% by weight based on the total weight of the radiation-curable gel ink composition, the ink's sprayability may be insufficient.

[0050] In one embodiment, the resin may have a molecular weight (M) in the range of 1000 g / mol to 75000 g / mol, for example 2000 g / mol to 50000 g / mol, for example 5000 g / mol to 25000 g / mol. w ).

[0051] In one embodiment, the one or more radiation-curable components are present in an amount of 40% to 90% by weight based on the total weight of the radiation-curable gel ink composition. Preferably, the one or more radiation-curable components may be present in an amount of 50% to 85% by weight based on the total weight of the radiation-curable gel ink composition, more preferably 60% to 80% by weight based on the total weight of the radiation-curable gel ink composition, such as 70% to 79% by weight based on the total weight of the radiation-curable gel ink composition.

[0052] If one or more radiation-curable components are present in an amount of less than 40% by weight based on the total weight of the radiation-curable gel ink composition, the ink may not provide a robust layer after curing.

[0053] In one embodiment, the one or more monofunctional radiation-curable components are present in an amount of 35% to 80% by weight based on the total weight of the radiation-curable gel ink composition.

[0054] Preferably, the one or more monofunctional radiation-curable components may be present in an amount of 40% to 75% by weight based on the total weight of the radiation-curable gel ink composition, more preferably 45% to 70% by weight based on the total weight of the radiation-curable gel ink composition, such as in an amount of 50% to 65% by weight based on the total weight of the radiation-curable gel ink composition.

[0055] When one or more monofunctional radiation-curable components are present in an amount less than 35% by weight based on the total weight of the radiation-curable gel ink composition, the viscosity of the ink may be too high, which could make the ink composition difficult to eject using an inkjet printhead. When one or more monofunctional radiation-curable components are present in an amount greater than 80% by weight based on the total weight of the radiation-curable gel ink composition, the amount of uncured monomers present in the cured ink layer may be too high.

[0056] In one embodiment, the radiation-curable gel ink composition further comprises a colorant, such as a pigment, dye, or a mixture thereof. Additionally, the radiation-curable inkjet ink composition may comprise a mixture of dyes and / or a mixture of pigments. The colorant may provide a predetermined color to the ink composition.

[0057] In one aspect of the invention, an ink set is provided, the ink set comprising a first radiation-curable gel ink composition and a second radiation-curable gel ink composition, the first radiation-curable gel ink composition being an ink composition according to the invention and comprising a first colorant, and the second radiation-curable gel ink composition being an ink composition according to the invention and comprising a second colorant different from the first colorant.

[0058] The ink set may contain a variety of different inks. For example, the ink set may be a CMYK ink set containing yellow, magenta, cyan, and black ink compositions. The ink set may further contain other colors, such as white, red, green, light magenta, light cyan, and / or gray. Additionally, the ink set may contain one or more metallic ink compositions. Optionally, the ink set may contain a base coat and / or an outer coat composition. The base coat and / or outer coat composition may be a colorless ink composition.

[0059] At least two inks in the ink group may contain polymeric photoinitiators and non-polymeric photoinitiators.

[0060] At least two of the ink compositions are radiation-curable gel ink compositions according to the present invention, which can provide printed matter with good adhesion on a variety of recording media.

[0061] In one aspect of the present invention, a method for preparing a radiation-curable gel ink composition according to the present invention is provided, the method comprising the following steps: a. Provide one or more radiation-curable components; b. Provide one or more gelling agents; c. Provide one or more inert resins; d. Mix the one or more gelling agents, the one or more radiation-curable components, and the one or more inert resins.

[0062] This method is therefore configured for preparing the ink composition according to the invention. One or more gelling agents, one or more radiation-curable components, and one or more inert resins can be provided. Optionally, additional components can be provided, such as additional solvents, one or more photoinitiators, one or more co-initiators, one or more inhibitors, and one or more surfactants. The one or more gelling agents, one or more radiation-curable components, and one or more inert resins can be provided in pure form, or they can be provided in solution or dispersion. Optionally, a colorant can be provided. When the colorant is a pigment, the pigment is preferably provided as a dispersion, such as a dispersion of pigment in one or more acrylates. The pigment dispersion may contain one or more dispersants and / or one or more synergists. Components can be provided immediately, or components can be added subsequently. Components can be added in any suitable order. When adding a dispersible component (e.g., a pigment), such a dispersible component is preferably added after the other components of the ink composition are provided. Mixing of the components can be carried out at any suitable temperature, for example, in the range of 50°C to 100°C, preferably in the range of 60°C to 85°C. Optionally, the ink can be filtered after mixing the components to remove unwanted solid particles from the ink composition.

[0063] In one aspect of the present invention, a method for printing an image onto a recording medium is provided, the method comprising the following steps: a. Spraying droplets of the radiation-curable ink composition according to the invention onto a recording medium; b. Curing the radiation-curable gel ink composition by irradiating the ink composition with ultraviolet light.

[0064] In this method, an image is applied to a recording medium. Specifically, in step a), the image is applied to the recording medium. The image can be applied using an ink composition according to the invention. The ink composition can be applied to the recording medium in a predetermined manner, for example, according to an image file stored on a suitable storage device. The image can be applied, for example, by ejecting droplets of a radiation-curable ink composition using an inkjet printhead.

[0065] Recording media can be in absorbent or non-absorbent media. Examples of recording media include plain paper, vinyl resin, corrugated cardboard, folding cartons, coated inkjet paper, uncoated inkjet paper, wallpaper, and fabric. Other examples of recording media include polyolefin media, such as polyethylene or polypropylene, for example, grooved PP; polystyrene media, PMMA film, rigid PMMA materials, rigid polycarbonate materials, dibond media, and polyester films, such as LFM450 and IJM778.

[0066] The recording medium can be a sheet-like medium, such as paper or vinyl ester sheets. Alternatively, the recording medium can be a rigid medium.

[0067] In this method, in step b), the radiation-curable gel ink composition is cured by irradiating the ink composition with ultraviolet light. Suitable radiation sources, such as halogen lamps, mercury lamps, and / or LED lamps, can be used to irradiate the inkjet ink composition. Optionally, multiple radiation sources can be used to irradiate the inkjet ink composition.

[0068] Recording media can be in absorbent or non-absorbent media. Examples of recording media include plain paper, vinyl resin, corrugated cardboard, folding cartons, coated inkjet paper, uncoated inkjet paper, wallpaper fabric, kraft paper, cellulose, coated paper, cotton, PET banners, PET canvas, PET film, PET mesh, PP film, PVC banners, PVC film, PVC mesh, SA PET, SA PP, SAV, blockout soft signage, frontlit soft signage, backlit soft signage, blockout soft signage, piled soft signage, structured soft signage, reflective signage, thick PVC film, SA PU, and SAV.

[0069] Other examples of recording media include polyolefin media, such as polyethylene or polypropylene, for example, grooved PP; polystyrene media, PMMA film, rigid PMMA material, rigid polycarbonate material, dibond media, polyester film, such as LFM450 and IJM778, corrugated cardboard, honeycomb structure, katzboard, solid bleached board, aluminum composite, forex, glass, high-pressure laminate, PET-G, ACM, plywood, and wood.

[0070] In one embodiment, the time interval between the droplets of the jet ink composition and the cured ink composition is at least 20 seconds.

[0071] The time interval between applying the radiation-curable ink and curing the radiation-curable ink can be at least 20 seconds, preferably at least 40 seconds. If the time interval between applying the radiation-curable gel ink and curing the radiation-curable gel ink is less than 20 seconds, an image containing multiple layers may be formed without intermediate ink curing. If the time interval between applying and curing the ink is at least 20 seconds, the ink can spread sufficiently to obtain good image quality.

[0072] This ink composition is a gel ink composition. When using a gel ink composition, no bleeding will occur even if the time interval between the droplets of the jet ink composition and the cured ink composition is 20 seconds or longer.

[0073] Optionally, the ink may be fixed (i.e. partially cured) shortly after being applied to the recording medium, and then fully cured after a time interval, such as 10 to 100 seconds.

[0074] In one embodiment, the ink is applied in multiple layers, and these layers are deposited before being irradiated with a radiation-curable ink.

[0075] A printed image may comprise multiple ink layers. Ink may be applied in multiple strips, with new ink strips applied over previously applied ink strips. Strips or layers may form an image together. All ink layers can be applied to the recording medium before curing the ink by irradiation. The use of radiation-curable gel inks allows for the application of relatively thick layers to the recording medium before curing the ink. Thick ink layers are difficult to cure because radiation needs to penetrate the thick ink layer to cure the entire layer, including the ink-recording medium interface, the layer itself, and the ink-air interface. This invention enables the efficient curing of the entire ink layer and the formation of printed matter with good print quality, including good surface curing.

[0076] In one aspect of the present invention, a printing press is provided, the printing press comprising: a. An ink applicator configured to apply a radiation-curable ink composition according to the invention onto a recording medium; b. A media carrier used to support the recording medium; c. Curing unit; and d. A controller configured to control the inkjet printer to perform the method according to the invention.

[0077] A printing press is also referred to as a printing apparatus. A printing press can be configured to apply radiation-curable ink during a printing operation. Suitable types of radiation-curable inks, including radiation-curable inkjet inks and radiation-curable gel inkjet inks, are known in the art. Preferably, the printing press can be an inkjet printer configured to apply ink to a recording medium to form an image by spraying ink droplets in a predetermined pattern onto the recording medium.

[0078] The printing apparatus includes an ink applicator. The ink applicator can be configured to apply a predetermined pattern of radiation-curable ink onto a recording medium during operation.

[0079] The ink applicator may include at least one inkjet printhead configured to jet ink onto the recording medium during operation. The printhead may be, for example, a thermal inkjet printhead or a piezoelectric inkjet printhead. The printing press may include multiple inkjet printheads. An image may be formed using one type or color of ink, but alternatively, more than one type and / or color of ink may be used. Cyan, magenta, yellow, and black inks may be used to form images. Additionally, one or more of white, brown, gray, light magenta, light cyan, red, green, orange, and purple inks may be used. Furthermore, one or more of a base coat composition, an outer coat composition, and metallic inks may be used. The printing unit may be a page-width printing unit or a scanning printing unit. The scanning printing unit may be configured to reciprocate in the scanning direction during operation. The scanning direction may be perpendicular to the media transport direction.

[0080] The printing press further includes a media carrier. The media carrier can be configured to support a recording medium during operation. Optionally, the recording medium can move in the media transport direction. The media carrier may include a flat platform. Optionally, the media carrier may include an annular belt. The media carrier may include holes for applying negative pressure. Applying negative pressure can hold the recording medium in place on the media carrier.

[0081] Optionally, the printing apparatus may include a media transport unit. The media transport unit may be configured to move the recording medium relative to the printing press in the media transport direction during operation.

[0082] The printing press further includes a curing unit. The curing unit is configured to irradiate a recording medium containing radiation-curable ink during operation. Irradiation of the radiation-curable ink causes a chemical reaction within the ink, resulting in the curing or pre-curing of the fluid. The curing unit can be a scan curing unit. Alternatively, the curing unit can be a page-width curing unit.

[0083] In one embodiment, one or more lamps may be positioned near the ink applicator, for example, on the printing carriage. These lamps may be located at the side edge of the printing carriage in the main scanning direction. The lamps positioned on the printing carriage may be pinning lamps for pre-curing the ink applied to the recording medium.

[0084] The printing press further includes a controller. The controller can control the printing press to perform the method according to the invention. Brief description of the attached diagram The invention will be more fully understood from the detailed description and accompanying drawings given below. The drawings are given by way of example only and are not intended to limit the invention. Figure 1 This is a schematic perspective view of a first example of a printing system according to the present invention in a first printing mode; Figure 2 This is a schematic perspective view of a second example of a printing system according to the present invention in a second printing mode; Figure 3 It is based on Figure 1 or Figure 2 A schematic diagram of the control unit of the photocopying system.

[0086] In the accompanying drawings, the same reference numerals denote the same elements.

[0087] Detailed description of the preferred implementation scheme The invention will now be described with reference to the accompanying drawings, wherein in several views, the same reference numerals are used to denote the same or similar elements.

[0088] Printing System Figure 1 Display printing apparatus. The printing apparatus is also called a printing press. The printing apparatus 1 includes a scanning printing unit 7 for printing on a recording medium 15. Figure 1 The recording medium 15 is a relatively rigid substrate, such as a panel. The recording medium 15 is supplied by a media input unit 14, which can be configured to store multiple such printing media 15 and supply them to the printing press 1. The printing press 1 includes a media carrier 4. The printing press 1 may further include a transport device for receiving and conveying the recording media 15 along the scanning printing unit 7. Figure 1In this design, the media carrier is specifically embodied as an annular belt 4. The annular belt is a conveyor belt 4 supported on a plurality of support rollers 3A, 3B, and 3C. At least one of the support rollers 3A, 3B, and 3C is equipped with a drive mechanism for moving the belt 4. The belt 4 is thus configured to support and convey the recording medium. Additionally, one or more of the support rollers 3A, 3B, and 3C can be configured to move and / or tilt to adjust and control the lateral position of the belt 4. The scanning printing unit 7 may be equipped with a sensor 8, such as a CCD camera, to determine the relative position of the belt 4 and / or the recording medium 15. Data from the sensor 8 can be used to control the position of the belt 4 and / or the recording medium 15. The belt 4 further comprises through-holes and a suction box 5 connected to a suction source (not shown) to allow negative pressure to be applied to the recording medium 15 via the through-holes in the belt 4. The negative pressure holds the recording medium 15 flatly against the belt 4 and prevents displacement of the recording medium 15 relative to the belt 4. Due to this holding, the belt 4 is able to convey the recording medium 15. It should be recognized that other suitable conveying devices, such as rollers and steppers, can be used as alternatives. The recording medium 15 can be conveyed gradually and / or in continuous motion.

[0089] The scanning printing unit 7 is configured to translate along the first guide beam 6 in the scanning direction. The scanning direction is perpendicular to the direction in which the printing medium is conveyed by the belt 4. The scanning printing unit 7 has multiple printheads (not shown) configured to spray various different marking materials (inks of different colors, primers, coatings, etc.) onto the recording medium 15. Each marking material used in the scanning printing unit 7 is stored in one of multiple containers, which are fluidly connected to their respective printheads to supply the marking material to the printheads for printing images on the recording medium 15.

[0090] The application of marking material, such as radiation-curable ink, from the printing unit is performed based on data provided in each printing operation. The printing unit may contain one or more inkjet printheads. The timing of the release of droplets of marking material from the one or more printheads determines their position on the recording medium 15. The timing can be adjusted based on the position of the printing unit 7 along the first guide beam 6. The aforementioned sensor 8 can be used here to determine the relative position and / or velocity of the printing unit 7 relative to the recording medium 15. Based on data from the sensor 8, the release timing of the marking material can be adjusted.

[0091] During the spraying of marking material, some marking material may spill and remain on the nozzle surface of the printhead. The presence of marking material on the nozzle surface can adversely affect droplet spraying and the positioning of these droplets on the recording medium 15. Therefore, it may be advantageous to remove excess marking material from the nozzle surface. Excess marking material can be removed, for example, by wiping with a wiper and / or by applying suitable moisture-resistant properties to the surface (e.g., provided by a coating).

[0092] The marking materials may require processing to properly fix them onto the printing medium. For this purpose, a fixing unit is provided downstream of the scanning unit. The fixing unit can emit radiation to facilitate the fixing process of the marking materials. Figure 1 In this example, the fixed unit is the scan-cured array 10.

[0093] The scanning curing unit includes at least one radiation emitting unit (not shown). During operation, the curing unit 10 reciprocates along the guide rail 17 in the scanning direction. Furthermore, the inkjet printing assembly 7 may have an additional fixing unit mounted on the same carriage as the fixed printhead. This additional fixing unit can be used to (partially) cure and / or harden the marking material, either independently of or in interaction with the fixing unit 10.

[0094] The scanning curing array 10 is configured to emit radiation of a specific frequency during operation, which interacts with the marking material, such as ultraviolet light in the case of UV-curable inks. Optionally (not shown), the scanning printing unit 7 may have an additional fixing unit disposed on the same carriage as the fixed printhead. This additional fixing unit may be used to (partially) cure and / or harden the marking material, independently of or interacting with the scanning curing array 10.

[0095] After printing and fixing, the recording medium 15 is conveyed to a receiving unit (not shown). The receiving unit may include a take-up roller for winding the recording medium 15, a receiving tray for supporting the sheet of the recording medium 15, or a rigid media processor similar to the media input unit 14. Optionally, the receiving unit may include processing means for processing the media after printing, such as post-processing equipment like a coating machine, folding machine, cutting machine, or punching machine.

[0096] The printing apparatus 1 also includes a user interface 11 for receiving print jobs and optionally for manipulating print jobs. The local user interface unit 11 is integrated into the printing engine and may include a display unit and a control panel. Alternatively, the control panel may be integrated into the display unit, for example, as a touchscreen control panel. The local user interface unit 11 is connected to a control unit 12 connected to the printing press 1. The control unit 12, such as a computer, includes a processor adapted to issue commands to the printing press 1, for example, to control the printing process. The printing press 1 may optionally be connected to a network. The network connection may be via cable or wireless. The printing press 1 can receive print jobs via the network. Furthermore, optionally, the control unit 12 of the printing press 1 may be provided with an input port, such as a USB port, so that print jobs can be sent to the printing press 1 via this input port.

[0097] Hybrid printing system Figure 1The printing press 1 in the text is a so-called hybrid printing press, capable of handling both flexible media and rigid substrates. Figure 1 In the first printing mode, the printing press 1 is configured to deliver a rigid substrate, such as a recording medium 15. This rigid printing medium 15 can be a panel, such as a panel for a door or wall, corrugated media, a sheet formed of plastic or metal, etc. To operate these rigid printing media 15, Figure 1 The printing press 1 is configured with a substantially linear transport path: starting from the media input device 14, the recording medium 15 moves forward along the scanning printing unit 7 at a substantially constant height. The media input unit 14 and the receiving unit are located at the level of the media support surface of the belt 4. Figure 2 In this process, a flexible roll medium 16 is supplied to the printing press 1. The roll medium 16 may be composed of, for example, paper, label paper, coated paper, plastic, or fabric. The roll medium 16 is supplied by the input roller 2A and extends through the belt 4 to the take-up roller 2B, where the roll medium 16 is rewound. The printing press 1 is configured to switch quickly and efficiently between printing modes.

[0098] also, Figure 2 The printing press 1 shown includes a page-width curing array 10. The page-width curing array extends in the main scanning direction. The page-width curing array does not move in the main scanning direction during operation. The page-width array can move in the media transport direction, which is perpendicular to the scanning direction.

[0099] control An embodiment of the control unit 12 is presented in more detail in Figure 3 In the middle. For example Figure 3 As shown, the control unit 12 includes a central processing unit (CPU) 31, a graphics processing unit (GPU) 32, random access memory (RAM) 33, read-only memory (ROM) 34, a network unit 36, an interface unit 37, a hard disk (HD) 35, and an image processing unit 39, such as a raster image processor (RIP). The aforementioned units 31-37 are interconnected via a bus system 38. However, the control unit 12 can also be a distributed control unit.

[0100] The CPU 31 controls the printing system 1 according to the control program stored in the ROM 34 or on the HD 35 and the local user interface panel 11. The CPU 31 also controls the image processing unit 39 and the GPU 32. The ROM 34 stores programs and data, such as boot programs, setup programs, and various setting data, which will be read and executed by the CPU 31. The hard disk 35 is an example of a non-volatile storage unit used to store and save programs and data so that the CPU 31 can perform the printing process, which will be described later. The hard disk 35 also includes an area for storing data for externally submitted printing jobs. Programs and data on the HD 35 are read by the CPU 31 onto the RAM 33 as needed. The RAM 33 has an area for temporarily storing programs and data read by the CPU 31 from the ROM 34 and the HD 35, as well as a working area used by the CPU 31 to perform various processes. The interface unit 37 connects the control unit 12 to client devices, such as the scanning device 21 and the printing system 1. Network unit 36 ​​connects control unit 12 to network N and is designed to provide communication with workstations (not shown) and other devices 21 that can be read via network N. Image processing unit 39 can be implemented as a software component running on the operating system of control unit 12 or as firmware, for example, embodied in a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC). Image processing unit 39 has the function of reading, interpreting, and rasterizing print job data. The print job data contains image data to be printed (i.e., fonts and graphics describing the content of the document to be printed, described in page description language, etc.), image processing attributes, and printing settings.

[0101] Experiments and Examples Material SR355, SR339C, SR506D, SR351, CN3755, and CN991 were obtained from Arkema; ​​Viscoat #200 from Osaka Chemical; ITX and EDB from Rahn; BYK 333 from BYK; pentaerythritol tetrastearate from TCIchemicals; BAPO from Arkema (Lambson); NeoCryl® B-302 from Covestro; and phenothiazine from Allessa. Cyan pigment as a dispersion (25% by weight pigment in SR9003) was obtained from Sun. MPI2000 was obtained from Avery. Unless otherwise stated, all materials were used as obtained.

[0102] SR355 is bis(trimethylolpropane)tetraacrylate, a tetrafunctional acrylate component with a molecular weight of 482 g / mol.

[0103] SR339C is 2-phenoxyethyl acrylate, a monofunctional acrylate with a molecular weight of 192 g / mol.

[0104] SR506D is isobornyl acrylate. It is a monofunctional acrylate with a molecular weight of 208 g / mol.

[0105] SR351 is trimethylolpropane triacrylate. It is a trifunctional acrylate with a molecular weight of 296 g / mol.

[0106] CN3755 is the molecular weight M W It is a bifunctional acrylated amine with a concentration of 800 g / mol.

[0107] CN991 is the molecular weight M W It is a bifunctional aliphatic urethane acrylate oligomer with a concentration of 1500 g / mol.

[0108] Viscoat #200 is a cyclic trimethylolpropane formal acrylate (CTFA). It is a monofunctional acrylate with a molecular weight of 200 g / mol.

[0109] NeoCryl® B-302 is an inert acrylic resin, in which M W = 5000.

[0110] ITX stands for isopropylthioxanthone, which is a photoinitiator.

[0111] BAPO is phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, which is a photoinitiator.

[0112] EDB is ethyl 4-(dimethylamino)benzoate, which is a co-initiator.

[0113] BYK 333 is an organosilicon-based surfactant.

[0114] Pentaerythritol tetrastearate is a gelling agent.

[0115] NeoCryl® B-302 is an inert resin and an acrylic resin.

[0116] Phenothiazine is an inhibitor.

[0117] Cyan pigment is used as a coloring agent.

[0118] method Printing methods Printed materials were produced on a Colorado 1650 printing press. The press was modified by replacing the scan curing unit with a page-width lamp. An MPI2000 was used as the recording medium.

[0119] The temperature of the printed surface is controlled at 24℃.

[0120] Ink formulation Ink compositions Ex 1 and CE 1 are prepared by providing the components shown in Table 1 in the amounts shown in Table 1 and mixing the components.

[0121] The first ink composition is ink composition Ex 1, which is an ink composition according to the present invention.

[0122] The second ink composition is ink composition CE 1, which is an ink composition not according to the present invention.

[0123] Table 1: Ink compositions Ex 1 and CE 1 .

[0124] For ink compositions Ex1 and CE1, calculate DBD and average functionality.

[0125] Table 2: DBD and average F of Ex1 .

[0126] Table 3: DBD and average F of CE1 .

[0127] This document discloses detailed embodiments of the invention; however, it is to be understood that the disclosed embodiments are merely examples of the invention, which can be embodied in various forms. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but rather serve only as the basis for the claims and as a representative basis for teaching those skilled in the art to use the invention differently in a practically and appropriately detailed manner. In particular, features presented and described in the individual dependent claims may be applied in combination, and any such combination of claims is disclosed herein.

[0128] Furthermore, the terminology and phrases used herein are not intended to be limiting; rather, they provide an understandable description of the invention. As used herein, the term "a" or "an" is defined as one or more. As used herein, the term "a plurality" is defined as two or more. As used herein, the term "another" is defined as at least a second or more. As used herein, the terms "comprising" and / or "having" are defined as including (i.e., open-ended language). As used herein, the term "coupled" is defined as a connection, but not necessarily a direct connection.

Claims

1. A radiation-curable gelling ink composition comprising a radiation-curable matrix and one or more gelling agents, wherein the radiation-curable matrix is ​​composed of one or more radiation-curable components and one or more inert resins, wherein the radiation-curable matrix has a double bond density (DBD) and an average functionality (average F), wherein the double bond density (DBD) is defined as: And the average functionality is defined as: in f i It is the functionality of a single component in the radiation-curable matrix; (wt%) i The percentage by weight of the individual component relative to the total weight of the radiation-curable gel ink composition in which the individual component is present; and (m w ) i It is the molecular weight of an individual component in the radiation-curable matrix, and The DBD is higher than 3, and the average functionality ranges from 0.9 to 1.

25.

2. The radiation-curable gelling ink composition according to claim 1, wherein the inert resin is present in an amount of 5% to 30% by weight based on the total weight of the radiation-curable gelling ink composition.

3. The radiation-curable gelling ink composition according to claim 1 or 2, wherein the inert resin has a molecular weight M in the range of 1000 g / mol to 75000 g / mol. W .

4. The radiation-curable gel ink composition according to any one of the preceding claims, wherein the one or more radiation-curable components are present in an amount of 40% to 90% by weight based on the total weight of the radiation-curable gel ink composition.

5. The radiation-curable gel ink composition according to any one of the preceding claims, wherein the one or more monofunctional radiation-curable components are present in an amount of 35% to 80% by weight based on the total weight of the radiation-curable gel ink composition.

6. The radiation-curable gel ink composition according to any one of the preceding claims, wherein the radiation-curable gel ink composition further comprises a colorant.

7. An ink group comprising a first radiation-curable gelling ink composition and a second radiation-curable gelling ink composition, wherein the first radiation-curable ink composition is an ink composition according to any one of claims 1-6 and comprises a first colorant, and the second radiation-curable ink composition is an ink composition according to any one of claims 1-6 and comprises a second colorant different from the first colorant.

8. A method for preparing an ink composition according to any one of claims 1 to 6, the method comprising the following steps: a. Provide one or more radiation-curable components; b. Provide one or more gelling agents; c. Provide one or more inert resins; d. Mix the one or more gelling agents, the one or more radiation-curable components, and the one or more inert resins.

9. A method for printing an image onto a recording medium, the method comprising the following steps: a. Spraying droplets of the radiation-curable inkjet ink composition according to any one of claims 1-6 onto a recording medium; b. Curing the radiation-curable inkjet ink composition by irradiating the ink composition with ultraviolet light.

10. The method of claim 9, wherein the time interval between ejecting droplets of the ink composition and curing the ink composition is at least 20 seconds.

11. A printing press, the printing press comprising: a. An ink applicator configured to apply a radiation-curable ink composition according to any one of claims 1-6 onto a recording medium; b. A media carrier used to support the recording medium; c. Curing unit; and d. A controller configured to control the inkjet printer to perform the method according to claim 9 or 10.

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