Inkjet printing ink and inkjet printing system comprising the inkjet printing ink

Abstract

The present invention relates to an inkjet printing ink. The present invention further relates to a set of inkjet printing inks, comprising the inkjet printing ink. The invention further relates to a container for providing inkjet printing ink to an inkjet printing system. Finally, the invention relates to an inkjet printing system comprising the container and the inkjet printing ink.

Description

Field of invention

[0001] The present invention relates to an inkjet printing ink. The present invention further relates to a set of inkjet printing inks, comprising the inkjet printing ink. The invention further relates to a container for providing inkjet printing ink to an inkjet printing system. Finally, the invention relates to an inkjet printing system comprising the container and the inkjet printing ink. Background of the invention

[0002] Inkjet printing is a special type of digital printing in which the design to be printed is created using suitable graphics software and applied directly to the substrate using an inkjet, which projects ink droplets with a volume typically measured in picoliters. The ink can be ejected continuously or only on demand (Drop On Demand, or DOD). In DOD systems, the droplet ejection mechanism can be twofold: thermal or piezoelectric. In the first case, each nozzle contains a resistor through which electrical pulses pass. With each pulse, the resistor heats up to several hundred degrees within a few microseconds, generating a vapor bubble in the ink it comes into contact with. The expansion of this bubble causes the droplet to be ejected from the nozzle above.In the second case, there is a small channel near each nozzle, in the vicinity of which a piezoelectric crystal is arranged; an electrical pulse causes the deformation of the crystal and consequently the sudden narrowing of the channel and the ejection of the ink.

[0003] In recent years, digital inkjet printing has become increasingly important as a printing method, as it offers several advantages over traditional printing methods such as screen printing. For example, digital inkjet printing eliminates the high costs of manufacturing screen printing tools, which are uneconomical for small print runs. Furthermore, digital inkjet printing allows for the creation of a large number of colors and gradients. Finally, faster inkjet printers suitable for industrial use are now available; these printers feature printheads with a large number of nozzles that are compatible with water-based inks.

[0004] Black inkjet printing inks containing black color pigments are known, for example, from US 2022 / 121219 A1.

[0005] To increase the cost-effectiveness of the printing process by increasing printing speed, the freshly printed inkjet printing ink can be dried using a drying unit, in particular by irradiating it with infrared radiation of different wavelengths, whereby the irradiation can be combined with convection (air drying).

[0006] Due to the higher absorption of infrared radiation by black pigments and their simultaneously low reflectivity, areas printed with inks containing high amounts of black pigment dry significantly faster than areas printed with inks containing no black pigment or only small amounts. The differing drying behaviors of inkjet printing inks result in a complex drying infrastructure, leading to limitations in drying and, consequently, printing speed.

[0007] Furthermore, the high absorption of infrared radiation by black pigments can lead to significant heating of the printed surfaces, potentially causing irreversible damage. This also negatively impacts the cost-effectiveness of the printing process. Object of the invention

[0008] It is therefore the object of the present invention to provide an inkjet printing ink which overcomes the disadvantages of the prior art, in particular to provide an inkjet printing ink which comprises no or only small amounts of black pigments and yet ensures a good black tone of a substrate to be printed. Disclosure of the invention

[0009] This problem is solved according to the subject matter of the independent claims. Preferred embodiments are described in the dependent claims and the following description.

[0010] The problem is solved in particular by an inkjet printing ink that includes a pigment composition, the pigment composition includes: - at least one blue pigment selected from the group consisting of PB15:3, PB15:4 and PB60; - at least one red pigment selected from the group consisting of PR122, PR170, PR175, PR176, PR187, PR188, PR207, PR242, PR254 and PR272; and - at least one yellow pigment selected from the group consisting of PY74, PY12, PY13, PY14, PY83, PY97, PY110, PY120, PY150, PY154, PY155, PY175, PY180, PY181, PY138, PY194, PY213 and PY214.

[0011] The problem is further solved by a set of inkjet printing inks comprising at least two differently colored inkjet printing inks, wherein - one of the differently colored inkjet printing inks, the inkjet printing inks according to the present invention; and - another of the differently colored inkjet printing inks is selected from the group consisting of a cyan inkjet printing ink, a yellow inkjet printing ink and a red inkjet printing ink.

[0012] The problem is further solved by a container for providing inkjet printing ink for an inkjet printing system, wherein - the container includes means for connecting the container to a printhead; - the container contains the inkjet printing ink according to the present invention; and - the means for connecting the container to the printhead are designed to enable the transport of the inkjet printing ink from the container to the printhead.

[0013] Finally, the task is solved by an inkjet printing system, including: - the container according to the present invention; and - a printhead. Inkjet printing ink

[0014] The inkjet printing ink according to the present invention comprises a pigment composition.

[0015] It may be provided that the inkjet printing ink comprises the pigment composition in an amount selected from the group consisting of 1 to 8 wt.%, 2 to 7 wt.%, 3 to 6 wt.%, and 5 to 6 wt.%, for example about 5.5 wt.%, based on the total weight of the inkjet printing ink.

[0016] It may be provided that the inkjet printing ink comprises the pigment composition in an amount of at least 1% by weight, at least 2% by weight, at least 3% by weight, at least 4% by weight, or at least 5% by weight, based on the total weight of the inkjet printing ink.

[0017] It may be provided that the inkjet printing ink comprises the pigment composition in an amount of not more than 8% by weight, not more than 7% by weight, or not more than 6% by weight, based on the total weight of the inkjet printing ink.

[0018] The pigment composition includes, essentially includes, or consists of - at least one blue pigment selected from the group consisting of PB15:3, PB15:4 and PB60; - at least one red pigment selected from the group consisting of PR122, PR170, PR175, PR176, PR187, PR188, PR207, PR242, PR254 and PR272; and - at least one yellow pigment selected from the group consisting of PY74, PY12, PY13, PY14, PY83, PY97, PY110, PY120, PY150, PY154, PY155, PY175, PY180, PY181, PY138, PY194, PY213 and PY214.

[0019] It may be provided that the inkjet printing ink comprises the pigment composition as the sole colorant, i.e., that the inkjet printing ink comprises no further pigments and / or dyes in addition to the pigment composition according to the present invention.

[0020] The pigment composition may comprise only one of the specified blue pigments or a mixture of two or more of the specified blue pigments. The pigment composition may comprise only one of the specified red pigments or a mixture of two or more of the specified red pigments. The pigment composition may comprise only one of the specified yellow pigments or a mixture of two or more of the specified yellow pigments.

[0021] It may be intended that the inkjet printing ink - the blue pigment in an amount selected from the group consisting of 0.5 to 2 wt.%, 0.7 to 1.6 wt.%, 0.85 to 1.3 wt.%, 1.0 to 1.2 wt.%, and 1.10 to 1.15 wt.%, for example about 1.12 wt.%, each based on the total weight of the inkjet printing ink; - the red pigment in an amount selected from the group consisting of 1.5 to 4.5 wt.%, 2.0 to 3.5 wt.%, 2.2 to 3.3 wt.%, 2.4 to 3.1 wt.%, 2.4 to 3.0 wt.%, 2.6 to 3.0 wt.%, for example about 2.8 wt.%, in each case based on the total weight of the inkjet printing ink; and - the yellow pigment in an amount selected from the group consisting of 0.1 to 2.7 wt.%, 0.2 to 2.7 wt.%, 0.4 to 2.2 wt.%, 0.7 to 1.8 wt.%, 1.1 to 1.7 wt.%, 1.2 to 1.6 wt.%, 1.3 to 1.5 wt.%, for example about 1.4 wt.%, in each case based on the total weight of the inkjet printing ink, includes.

[0022] The inkjet printing ink according to the present invention can be referred to as a colored black ink. A colored black ink, in this context, is an ink that produces a black tint on a substrate comparable to a black tint achieved with an ink containing high amounts of black pigment, wherein the colored black ink may be characterized by containing less than 1 wt.% black pigment such as PBK7, based on the total weight of the colored black ink, and preferably no black pigment. Blue pigment

[0023] The blue pigment is selected from the group consisting of PB15:3, PB15:4, and PB60. It may be specified that the blue pigment is selected from PB15:3 and PB15:4. It may be specified that the blue pigment is PB15:3. It may be specified that the blue pigment is PB15:4. The use of these blue pigments allows for the achievement and improvement of black levels and contrast.

[0024] The blue pigment may be contained in the inkjet printing ink in an amount of at least 0.5 wt.%, at least 0.7 wt.%, at least 0.85 wt.%, at least 1.0 wt.%, or at least 1.10 wt.%, for example about 1.12 wt.%, in each case based on the total weight of the inkjet printing ink.

[0025] The blue pigment may be included in the inkjet printing ink in an amount selected to be at most 2 wt.%, at most 1.6 wt.%, at most 1.3 wt.%, at most 1.2 wt.%, and / or at most 1.15 wt.%, for example about 1.12 wt.%, in each case based on the total weight of the inkjet printing ink.

[0026] The blue pigment may be included in an amount selected from the group consisting of 0.5 to 2 wt.%, 0.7 to 1.6 wt.%, 0.85 to 1.3 wt.%, 1.0 to 1.2 wt.%, and 1.10 to 1.15 wt.%, for example about 1.12 wt.%, in each case based on the total weight of the inkjet printing ink. Red pigment

[0027] The red pigment is selected from the group consisting of PR122, PR170, PR175, PR176, PR187, PR188, PR207, PR242, PR254 and PR272.

[0028] The red pigment can be PR122. Using red pigments can achieve and improve black levels and contrast.

[0029] The red pigment may be present in the inkjet printing ink in an amount of at least 1.5 wt.%, at least 2.0 wt.%, at least 2.2 wt.%, at least 2.4 wt.%, at least 2.6 wt.%, or at least 2.7 wt.%, for example about 2.8 wt.%, in each case based on the total weight of the inkjet printing ink.

[0030] The red pigment may be present in the inkjet printing ink in an amount of not more than 4.5 wt.%, not more than 3.5 wt.%, not more than 3.3 wt.%, not more than 3.0 wt.%, or not more than 2.9 wt.%, for example about 2.8 wt.%, in each case based on the total weight of the inkjet printing ink.

[0031] The red pigment may be included in an amount selected from the group consisting of 1.5 to 4.5 wt.%, 2.0 to 3.5 wt.%, 2.2 to 3.3 wt.%, 2.4 to 3.1 wt.%, 2.4 to 3.0 wt.%, 2.6 to 3.0 wt.%, for example about 2.8 wt.%, in each case based on the total weight of the inkjet printing ink. Yellow pigment

[0032] The yellow pigment is selected from the group consisting of PY74, PY12, PY13, PY14, PY83, PY97, PY110, PY120, PY150, PY154, PY155, PY175, PY180, PY181, PY138, PY194, PY213 and PY214.

[0033] The yellow pigment can be PY74. Using yellow pigments can achieve and improve black levels and contrast.

[0034] The yellow pigment may be present in the inkjet printing ink in an amount of at least 0.1 wt.%, at least 0.2 wt.%, at least 0.4 wt.%, at least 0.7 wt.%, at least 1.1 wt.%, at least 1.2 wt.%, or at least 1.3 wt.%, for example about 1.4 wt.%, in each case based on the total weight of the inkjet printing ink.

[0035] The yellow pigment may be present in the inkjet printing ink in an amount of not more than 2.7 wt.%, not more than 2.2 wt.%, not more than 1.8 wt.%, not more than 1.7 wt.%, not more than 1.6 wt.%, or not more than 1.5 wt.%, for example about 1.4 wt.%, in each case based on the total weight of the inkjet printing ink.

[0036] The yellow pigment may be included in an amount selected from the group consisting of 0.1 to 2.7 wt.%, 0.2 to 2.7 wt.%, 0.4 to 2.2 wt.%, 0.7 to 1.8 wt.%, 1.1 to 1.7 wt.%, 1.2 to 1.6 wt.%, 1.3 to 1.5 wt.%, for example about 1.4 wt.%, in each case based on the total weight of the inkjet printing ink. Orange pigment

[0037] The pigment composition may also include an orange pigment. This orange pigment may be PO34. The use of orange pigments can improve black levels and contrast. Violet pigment

[0038] The pigment composition may include a violet pigment. The violet pigment may be selected from the group consisting of PV23 and PV19. The violet pigment may be PV23. The use of violet pigments can improve black levels and contrast.

[0039] The pigment composition may include both an orange and a violet pigment. Using a combination of orange and violet pigments can further improve black levels and contrast.

[0040] The violet pigment may be present in the inkjet printing ink in an amount of at least 1.0 wt.%, at least 1.5 wt.%, at least 1.8 wt.%, at least 2.0 wt.%, at least 2.1 wt.%, or at least 2.2 wt.%, for example about 2.3 wt.%, in each case based on the total weight of the inkjet printing ink.

[0041] The violet pigment may be present in the inkjet printing ink in an amount of not more than 4.5 wt.%, not more than 3.5 wt.%, not more than 3.0 wt.%, not more than 2.5 wt.%, or not more than 2.4 wt.%, for example about 2.3 wt.%, in each case based on the total weight of the inkjet printing ink.

[0042] The violet pigment may be included in an amount selected from the group consisting of 1.0 to 4.5 wt.%, 1.5 to 3.5 wt.%, 1.8 to 3.0 wt.%, 2.0 to 2.7 wt.%, 2.1 to 2.5 wt.%, 2.2 to 2.4 wt.%, for example about 2.3 wt.%, in each case based on the total weight of the inkjet printing ink. Black pigment

[0043] It can be provided that the inkjet printing ink contains no more than 1% by weight of black pigment, preferably less than 1% by weight, based on the total weight of the inkjet printing ink, wherein the black pigment can in particular be carbon black, for example PBK7. This allows the black level and contrast to be improved without unduly impairing the drying properties of the ink.

[0044] It may be specified that the inkjet printing ink does not contain black pigment. It may be specified that the inkjet printing ink does not contain carbon black. It may be specified that the inkjet printing ink does not contain PBK7. This can further improve the drying properties of the ink.

[0045] The inkjet printing ink may contain the black pigment in an amount selected from the group consisting of 0.001 to 1.0 wt.%, preferably less than 1.0 wt.%, 0.01 to 0.8 wt.%, 0.05 to 0.5 wt.%, 0.07 to 0.3 wt.%, 0.1 to 0.2 wt.% and 0.12 to 0.16 wt.%, for example about 0.14 wt.%, based on the total weight of the inkjet printing ink.

[0046] The inkjet printing ink may contain the black pigment in an amount of at least 0.001 wt.%, at least 0.01 wt.%, at least 0.05 wt.%, at least 0.07 wt.%, at least 0.1 wt.%, or at least 0.12 wt.%, for example about 0.14 wt.%, based on the total weight of the inkjet printing ink.

[0047] The inkjet printing ink may contain the black pigment in an amount of at most 0.95 wt.%, at most 0.8 wt.%, at most 0.5 wt.%, at most 0.3 wt.%, at most 0.2 wt.%, at most 0.16 wt.%, for example about 0.14 wt.%, based on the total weight of the inkjet printing ink.

[0048] The pigment composition may include an orange pigment, a violet pigment, and a black pigment, wherein the black pigment is present in an amount of at most, preferably less than, 1% by weight, based on the total weight of the inkjet printing ink.

[0049] The pigment composition may include an orange pigment, a violet pigment, and a black pigment, wherein the black pigment is present in an amount of at most, preferably less than, 1% by weight, based on the total weight of the inkjet printing ink. Water

[0050] The inkjet printing ink according to the present invention can further comprise water. It is preferred that deionized or demineralized water is used. This makes it possible to avoid the introduction of unwanted impurities, such as hardness-causing minerals like calcium and magnesium, etc.

[0051] It may be provided that the inkjet printing ink contains water as the predominant solvent, preferably in an amount of at least 50% by weight, based on the total amount of solvent in the inkjet printing ink.

[0052] It may be provided that the inkjet printing ink comprises water in an amount of 10 to 80 wt.%, based on the total weight of the inkjet printing ink.

[0053] It may be provided that the inkjet printing ink contains water in an amount of at least 10 wt.%, at least 15 wt.%, at least 20 wt.%, at least 25 wt.%, at least 30 wt.%, at least 35 wt.%, at least 40 wt.%, at least 45 wt.%, at least 50 wt.%, or at least 55 wt.%, in each case based on the total weight of the inkjet printing ink.

[0054] It may be provided that the inkjet printing ink contains water in an amount of not more than 80% by weight, not more than 75% by weight, not more than 70% by weight, not more than 65% by weight, or not more than 60% by weight, in each case based on the total weight of the inkjet printing ink.

[0055] The inkjet printing ink may contain water in an amount of 25 to 75 wt.%, 40 to 70 wt.%, 50 to 70 wt.%, or 55 to 65 wt.%, for example about 60 wt.%, in each case based on the total weight of the inkjet printing ink.

[0056] The specified preferred amounts of water in the inkjet printing ink enabled optimized black coloring on the one hand and drying of the ink on the other. binder

[0057] The inkjet printing ink may further comprise a binder or a mixture of several binders, for example, a mixture of up to four different binders. Alternatively, the inkjet printing ink may not comprise a binder.

[0058] It may be provided that the inkjet printing ink comprises the binder in an amount selected from the group consisting of 0.01 to 20 wt.%, 1 to 10 wt.%, 4 to 8 wt.%, 5 to 7 wt.%, for example about 6 wt.%, in each case based on the total weight of the inkjet printing ink.

[0059] It may be provided that the inkjet printing ink comprises the binder in an amount of at least 0.01 wt.%, at least 1 wt.%, at least 4 wt.%, or at least 5 wt.%, in each case based on the total weight of the inkjet printing ink.

[0060] It may be provided that the inkjet printing ink comprises the binder in an amount of not more than 20% by weight, not more than 10% by weight, not more than 8% by weight, or not more than 7% by weight, in each case based on the total weight of the inkjet printing ink.

[0061] Appropriate amounts of binder are advantageous with regard to the durability of the printed product and the drying properties of the ink.

[0062] The binder can be used in inkjet printing ink as a solid and / or as an aqueous binder preparation; that is, it can be used in these forms to manufacture the inkjet printing ink. In this context, an aqueous binder preparation is, in particular, a binder solution or a binder dispersion.

[0063] It is preferred that a binder dispersion is used to produce the inkjet printing ink according to the invention. In such a case, the amount of binder in the inkjet printing ink is specified with reference to the total weight of the binder dispersion (including solvent, etc.). By using a suitable binder dispersion to produce the inkjet printing ink according to the invention, an advantageous mixing of the components of the inkjet printing ink can be achieved.

[0064] The binder may be a synthetic polymeric binder, preferably a polyacrylate, a polyurethane, a polyester, a sulfopolyester, a maleate resin, or a copolymer of two or more of these, or a wax, for example beeswax.

[0065] For example, the binder could be Acronal 12DE (dispersion of an acrylonitrile-acrylic acid ester copolymer, BASF), Neocryl XK166N (dispersion of an acrylic styrene copolymer, Covestro), NeoRez R-3972 (polyurethane dispersion, Covestro), Eastek 1000 (colloidal solution of a sulfopolyester, Eastman), or Neocryl XK-39 (alkali-soluble polyacrylate dispersions, Covestro).

[0066] It is preferred that the binder is an acrylic styrene copolymer, a sulfopolyester, or a mixture thereof, preferably a mixture of an acrylic styrene copolymer and a sulfopolyester. It is further preferred that the binder is a mixture of an acrylic styrene copolymer and a sulfopolyester in a weight ratio of 10:1 to 1:2, more preferably 5:1 to 1:1.5, and even more preferably 3:1 to 1:1, for example, about 2:1.

[0067] For example, the binder can be a mixture of Neocryl XK-39 and an acrylate-styrene copolymer in a weight ratio of 10:3. Preservative / Biocide

[0068] The inkjet printing ink may further comprise 0.001 to 0.1 wt.%, based on the total weight of the inkjet printing ink, of a preservative and / or a biocide. The specified amount refers to the weight of the preservative. Preferred preservatives are, for example, a mixture of tert-butyl hydroperoxide and monophenyl glycol ether, particularly preferably a mixture of 12 to 60 wt.% tert-butyl hydroperoxide and 3 to 50 wt.% monophenyl glycol ether, or a mixture of 1,6-dihydroxy-2,5-dioxahexane and tetramethylolacetylenediurea. Such a preservative is particularly suitable for aqueous solutions and emulsions. A preferred biocide is, for example, a mixture of 2-bromo-2-nitropropane-1,3-diol and 2-octyl-2H-isothiazol-3-one or a mixture of BIT (1,2-benzisothiazolin-3-one), MIT (2-methyl-4-isothiazolin-3-one) and OIT (2-octyl-2H-isothiazol-3-one), which particularly prevents contamination.Another preferred biocide is a mixture of CIT / MIT in a weight ratio of 3:1. Another preferred biocide is 2-bromo-2-nitropropane-1,3-diol. Another preferred biocide is 2-octyl-2H-isothiazol-3-one. Another preferred biocide is phenoxyethanol.

[0069] It is preferred that the inkjet printing ink contains the preservative and / or the biocide in a total amount of at least 0.001 wt.%, particularly preferably at least 0.005 wt.%, further preferably at least 0.008 wt.%, most preferably at least 0.01 wt.%, in each case based on the total weight of the inkjet printing ink.

[0070] It is preferred that the inkjet printing ink contains the preservative and / or the biocide in a total amount of at most 0.1 wt.%, particularly preferably at most 0.05 wt.%, further preferably at most 0.03 wt.%, most preferably at most 0.02 wt.%, in each case based on the total weight of the inkjet printing ink.

[0071] It is preferred that the inkjet printing ink contains the preservative and / or the biocide in a total amount of 0.025 to 0.4 wt.%, particularly preferably 0.001 to 0.05 wt.%, and more preferably 0.02 to 0.04 wt.%, each based on the total weight of the inkjet printing ink. Drying retarder

[0072] The inkjet printing ink may comprise a drying retarder. The inkjet printing ink may contain the drying retarder in an amount of 0.01 to 40% by weight, based on the total weight of the ink. Preferably, the drying retarder is an organic polyol and / or polyglycol and / or a sugar alcohol and / or a polar organic compound that is liquid at room temperature and under normal pressure, particularly preferably selected from the group consisting of: consisting of diethylene glycol, propylene glycol, 1,2-propanediol, glycerin, trimethylolpropane, di-trimethylolpropane, neopentyl glycol, erythritol, dimethyl sulfoxide, pyrrolidones, in particular 2-pyrrolidone or N-methyl-2-pyrrolidone (NMP) and mixtures thereof, particularly preferably 1,2-propanediol.

[0073] It is preferred that the inkjet printing ink contains the drying retarder in an amount of at least 1 wt.%, particularly preferably at least 5 wt.%, more preferably at least 7.5 wt.%, most preferably at least 8 wt.%, in each case based on the total weight of the inkjet printing ink.

[0074] It is preferred that the inkjet printing ink contains the drying retarder in an amount of at most 30 wt.%, particularly preferably at most 20 wt.%, further preferably at most 15 wt.%, and moreover preferably at most 10 wt.%, in each case based on the total weight of the inkjet printing ink.

[0075] It is preferred that the inkjet printing ink contains the drying retarder in an amount of 1 to 30 wt.%, particularly preferably 5 to 20 wt.%, more preferably 7.5 to 15 wt.%, most preferably about 8 to 10 wt.%, in each case based on the total weight of the inkjet printing ink.

[0076] By using appropriate amounts of drying retarders, the drying properties of inkjet printing ink can be improved, especially during infrared drying. pH adjuster

[0077] The inkjet printing ink may further comprise 0.01 to 3% by weight, based on the total weight of the inkjet printing ink, of a pH adjusting agent. The pH adjusting agent may be a base or a pH buffer. It is preferred that the pH adjusting agent be a base. Preferably, an amine, particularly preferably a low-odor or odorless amine, such as N-butylaminoethanol, 2-butylaminoethanol, triethanolamine, 2-amino-2-methylpropanol, or tris(hydroxymethyl)aminomethane, preferably triethanolamine, may be used as the base.

[0078] It is preferred that the inkjet printing ink contains the pH adjusting agent in an amount of at least 0.1 wt.%, particularly preferably at least 0.3 wt.%, further preferably at least 0.5 wt.%, most preferably at least 0.6 wt.%, in each case based on the total weight of the inkjet printing ink.

[0079] It is preferred that the inkjet printing ink contains the pH adjusting agent in an amount of at most 2.5 wt.%, particularly preferably at most 2 wt.%, further preferably at most 1 wt.%, most preferably at most 0.75 wt.%, in each case based on the total weight of the inkjet printing ink.

[0080] It is preferred that the inkjet printing ink contains the pH adjusting agent in an amount of 0.1 to 3 wt.%, particularly preferably 0.3 to 2 wt.%, further preferably 0.5 to 1 wt.%, most preferably 0.6 to 0.75 wt.%, in each case based on the total weight of the inkjet printing ink.

[0081] By using appropriate pH adjusting agents in the appropriate quantities, the properties of the inkjet printing ink and the resulting printed product can be specifically adjusted. Other solvent

[0082] It can be provided that water is the only solvent in the inkjet printing ink according to the invention. Alternatively, it can be provided that the inkjet printing ink according to the invention comprises, in addition to water, another solvent, in particular an organic solvent.

[0083] It can be provided that the inkjet printing ink contains the further solvent in an amount of at least 0.1 wt.%, particularly preferably at least 1 wt.%, most preferably at least 3 wt.%, in each case based on the total weight of the inkjet printing ink.

[0084] It is preferred that the inkjet printing ink contains the further solvent in an amount of at most 40 wt.%, more preferably at most 30 wt.%, further preferably at most 20 wt.%, more preferably at most 10 wt.%, most preferably at most 7.5 wt.%, in each case based on the total weight of the inkjet printing ink.

[0085] It is preferred that the inkjet printing ink contains the further solvent in an amount of 0.1 to 40 wt.%, more preferably 1 to 10 wt.%, most preferably 4 to 6 wt.%, in each case based on the total weight of the inkjet printing ink.

[0086] It is preferred that the further solvent is a water-soluble organic solvent, more preferably an alcohol, and furthermore preferably a monohydric alcohol, most preferably isopropyl alcohol.

[0087] By adding the additional solvent to the composition according to the invention, improved solubility behavior can be achieved for substances, such as pigments, which are sparingly soluble in water. Other additives

[0088] It may be provided that the inkjet printing ink according to the present invention comprises one or more further additives, which may in particular be selected from the group consisting of a wetting additive (for example, a polyether-modified polysiloxane), a leveling additive (for example, a polyethersiloxane), a rheology additive (for example, an alcohol alkoxylate) and a thickener (for example, a polyacrylate ester).

[0089] The additional additive(s) may be included in the inkjet printing ink in a quantity selected from the group consisting of 0.1 to 5 wt.%, 0.5 to 3 wt.%, and 0.8 to 1.5 wt.%, respectively, based on the total weight of the inkjet printing ink.

[0090] By adding appropriate further additives, the inkjet printing ink can be optimized for the respective purpose, especially with regard to black coloring and drying properties. Set of inkjet printing inks

[0091] The set of inkjet printing inks according to the present invention comprises at least two differently colored inkjet printing inks. One of the differently colored inkjet printing inks is the inkjet printing ink according to the present invention as described above.

[0092] The set of inkjet printing inks includes at least one other differently colored inkjet printing ink, selected from the group consisting of a cyan inkjet printing ink, a yellow inkjet printing ink, and a red inkjet printing ink.

[0093] In the set of inkjet printing inks, the differently colored inkjet printing inks are stored separately from each other, for example in different containers that contain the respective inkjet printing inks.

[0094] For example, differently colored inkjet printing inks, which constitute the set of inkjet printing inks, can be contained in a plurality (plurality here meaning at least two) of containers, with each of the differently colored inkjet printing inks being contained in a separate container. The containers can each have means designed to transport the respective differently colored inkjet printing ink from the respective container to a single printhead.

[0095] The means are those for connecting the respective container to the printhead. These means may include hoses, tubes, etc., which enable the transport of the differently colored inkjet printing ink from the respective container to the printhead. The means may also include a filter and / or a pressure equalization tank and / or other suitable means. Furthermore, the means may be a connection designed to connect other means, such as tubes or hoses, to the container.

[0096] In an alternative embodiment, the differently colored inkjet printing inks can be provided separately from one another in a plurality of chambers, for example in the individual chambers of an inkjet printing cartridge. Container for supplying inkjet printing ink to an inkjet printing system

[0097] The container for providing inkjet printing ink for an inkjet printing system according to the present invention contains the inkjet printing ink according to the present invention as described above.

[0098] The container is not limited in terms of its volume, although a volume in the range of 5 L to 800 L may be preferred.

[0099] The container has means for connecting it to a printhead. These means are designed to transport the inkjet printing ink from the container to the printhead and may include, in particular, hoses, tubes, etc., which facilitate the transport of the inkjet printing ink from the container to the printhead. The means may include, or simply consist of, connections designed to connect the container to the printhead and / or hoses / tubes, etc. The means may further include a filter and / or a pressure equalization tank and / or other suitable means. In addition to the components already mentioned, the means may also include the printer itself, of which suitable inkjet printers are known to those skilled in the art.

[0100] In an alternative embodiment, the container is part of an inkjet printer cartridge. inkjet printing system

[0101] The inkjet printing system according to the present invention comprises the reservoir according to the invention and a printhead. The inkjet printing system according to the present invention can further comprise a printer, i.e., an inkjet printer, which is connected to the reservoir on one side and the printhead on the other, and which enables the transport of the inkjet printing ink from the reservoir to the printhead.

[0102] Any printhead designed for inkjet printing can be used. Generally, the printhead is designed to be connected to the ink reservoir so that the ink can be transported from the reservoir to the printhead. The printhead can also be designed to spray the ink droplets onto a substrate without contact, for example, in continuous inkjet printing or dot-on-dot (DOD) inkjet printing. The printhead can operate in single-pass or multi-pass mode.

[0103] The inkjet printing system can further comprise at least one additional reservoir, wherein the additional reservoir contains a further inkjet printing ink selected from the group consisting of a cyan ink, a yellow ink, and a red ink; the additional reservoir comprises means for connecting the additional reservoir to the printhead, wherein the means for connecting the additional reservoir to the printhead are configured to transport the additional ink from the additional reservoir to the printhead. Preferred embodiments in this regard are also described above with respect to the set of inkjet printing inks and the reservoir. Effect of the invention

[0104] Using the inkjet printing ink according to the invention, comparable black tones can be obtained in inkjet printing that are comparable to black tones obtained using inks containing large amounts of black pigment. In particular, comparable black tones can be achieved with only small amounts (less than 1% by weight based on the total weight of the ink) of black pigment in the ink. Acceptable results with regard to blackness and contrast could also be achieved without any black pigment in the ink.

[0105] At the same time, the inkjet printing ink according to the invention exhibits improved drying behavior, in particular improved absorption behavior, and thus the possibility of drying the inkjet printing ink by means of infrared drying. Improved drying behavior can consist of the drying time of the inkjet printing ink according to the invention being similar to the drying time of colored (non-black) inks. This results in a simplified drying infrastructure in combination with homogeneous drying behavior and thus optimized added value.

[0106] Furthermore, the reduced energy absorption capacity resulting from the reduced or non-use of black pigment prevents damage to black / dark areas of the substrate. This has a positive impact on the economic operation of the systems. General Definitions

[0107] Unless expressly stated otherwise, a feature specified in the singular (a, an...) also includes the plural. For example, if it is stated that the inkjet printing ink according to the invention contains a pigment, this also includes the case in which the inkjet printing ink contains a mixture of several pigments.

[0108] Unless expressly stated otherwise, terms such as "comprising", "containing", etc., include the meanings "essentially comprising", "essentially containing", or "consisting of". "Essentially comprising" in this context can mean "comprising at least 50% by weight", "comprising at least 70% by weight", "comprising at least 80% by weight", "comprising at least 90% by weight", "comprising at least 95% by weight", "comprising at least 98% by weight", "comprising at least 99% by weight", in each case based on the total weight of the material / mixture that substantially comprises the component.

[0109] The quantities specified for the inkjet printing ink according to the invention add up to a total quantity of 100 wt.% and thus give the total quantity of the inkjet printing ink.

[0110] The pigments of the present invention are designated by the designation “CI”, introduced by the Society Dyers and Colourists, Dradford, Yorkshire, UK, published in the Color Index, 3rd edition, 1971. Examples of implementation, recipe example 1 43,05 g Deionized water 0,15 g Microbicide based on isothiazolones (biocide for preservation) 3,0 g 42% aqueous acrylate-styrene copolymer dispersion (binder) 10,0 g NeoCryl XK-39 (binder) 0,5 g Triethanolamine (pH adjusting agent) 9,0 g 1,2-Popanediol (drying retarder) 5,0 g Isopropyl alcohol (co-solvent) 24,0 g Pigment composition 1 1,5 g polyether-modified polysiloxane (wetting additive) 1,5 g Polyethersiloxane (progressive additive) 1,5 g Alcohol alkoxylates (rheology additive) 0,8 g Polyacrylate esters (thickener) Pigment composition 1: 20.20 wt.% CIPigment Blue 15:4 Dispersion (Solid pigment 23 wt.%) 50.50 wt.% CIPigment Red 122 Dispersion (Solid pigment 23 wt.%) 25.50 wt.% CIPigment Yellow 74 Dispersion (Solid pigment 23 wt.%) 3.80 wt.% CIPigment Black 7 Dispersion (Solid Pigment 15%) Comparative formula 43,05 g Deionized water 0,15 g Microbicide based on isothiazolones (biocide for preservation) 3,0 g 42% aqueous acrylate-styrene copolymer dispersion (binder) 10,0 g NeoCryl XK-39 (binder) 0,5 g Triethanolamine (pH adjusting agent) 9,0 g 1,2-Popanediol (drying retarder) 5,0 g Isopropyl alcohol (co-solvent) 24,0 g Pigment composition 2 1,5 g polyether-modified polysiloxane (wetting additive) 1,5 g Polyethersiloxane (progressive additive) 1,5 g Alcohol alkoxylates (rheology additive) 0,8 g Polyacrylate esters (thickener) Pigment composition 2: 15.0 wt.% soot 85.0 wt.% Water Experimental examples and procedure: Example 1

[0111] A single-sided coated lightweight cardboard (with CTP primer) was used as the substrate and printed with an ink according to formulation example 1 (Example 1). Printing was carried out using a rotary printing device with a printing speed of 50 m / s and a Fuji Samba printhead. The ink was printed across the entire surface. The resolution was 1200 x 600 dpi. Comparative example 1

[0112] The comparison example was produced according to example 1, with the sole exception that a composition according to the comparison recipe was used as the ink instead of the recipe example 1.

[0113] Immediately after printing the substrate, the applied ink was dried with a dryer capacity of 7.6 kW at 15 m / min, 2 passes, and the temperature at the dryer outlet was measured across the entire surface immediately afterwards.

[0114] The densities and LAB values ​​of the printed products were then measured using the eXact spectrophotometer.

[0115] The measurement parameters were as follows: d50 (light source. D=daylight, 50 = 5000 Kelvin light temperature) 2° normal observer,

[0116] Measurement without filter.

[0117] LAB value: L = Brightness A-value: Green-red axis (a positive A-value indicates the red part of the axis) B-value: Blue-yellow axis (a negative B-value indicates the blue part of the axis) Example 1: Measured density (average of 6 measurement points): 1 1.58 g / cm 3 Measured LAB value (mean of 6 measurement points): L = 19.5 a = -3.92 b = -2.46 Temperature measured at dryer outlet across the entire surface; 73 °C Comparative example 1: Measured density (average of 6 measurement points): 1.72 g / cm 3 Measured LAB value (mean of 6 measurement points): L = 15.17 a = -0.86 b = -3.55 Measured temperature at dryer outlet across the entire surface: 129 °C

[0118] The printed product according to example 1 shows a good black coloration (low L-value, i.e. low brightness) comparable to comparison example 1, while simultaneously having a significantly reduced drying temperature.

[0119] The features of the invention disclosed in the foregoing description and in the claims can be essential for the realization of the invention in its various embodiments, both individually and in any combination. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 2022 / 121219 A1

[0004]

Claims

[1] An inkjet printing ink comprising a pigment composition, wherein the pigment composition comprises: - at least one blue pigment selected from the group consisting of PB15:3, PB15:4 and PB60; - at least one red pigment selected from the group consisting of PR122, PR170, PR175, PR176, PR187, PR188, PR207, PR242, PR254 and PR272; and - at least one yellow pigment selected from the group consisting of PY74, PY12, PY13, PY14, PY83, PY97, PY110, PY120, PY150, PY154, PY155, PY175, PY180, PY181, PY138, PY194, PY213 and PY214. [2] The inkjet printing ink according to claim 1, wherein the pigment composition further comprises an orange pigment, wherein the orange pigment is PO34. [3] The inkjet printing ink according to any of the preceding claims, wherein the pigment composition further comprises at least one violet pigment selected from the group consisting of PV23 and PV19 [4] The inkjet printing ink according to any of the preceding claims, wherein the pigment composition further comprises at least one black pigment, wherein - the black pigment PBK7 is; and - the black pigment is contained in an amount of no more than 1% by weight, based on the total weight of the inkjet printing ink. [5] The inkjet printing ink according to any of the preceding claims, wherein the inkjet printing ink comprises the pigment composition in an amount of 1 to 8 wt. %, based on the total weight of the inkjet printing ink. [6] The inkjet printing ink according to any of the preceding claims, wherein the inkjet printing ink - the blue pigment in an amount of 0.5 to 2% by weight, based on the total weight of the inkjet printing ink; - the red pigment in an amount of 1.5 to 4.5% by weight, based on the total weight of the inkjet printing ink; and - the yellow pigment in an amount of 0.1 to 2.7% by weight, based on the total weight of the inkjet printing ink. [7] The inkjet printing ink according to any of the preceding claims, wherein the inkjet printing ink further comprises water. [8] The inkjet printing ink according to any of the preceding claims, wherein the inkjet printing ink further comprises a binder. [9] A set of inkjet printing inks comprising at least two differently colored inkjet printing inks, wherein - one of the differently colored inkjet printing inks is the inkjet printing ink according to one of the preceding claims; and - another of the differently colored inkjet printing inks is selected from the group consisting of a cyan inkjet printing ink, a yellow inkjet printing ink and a red inkjet printing ink. [10] A container for providing inkjet printing ink for an inkjet printing system, wherein - the container includes means for connecting the container to a printhead; - the container contains the inkjet printing ink according to any one of claims 1 to 9; and - the means for connecting the container to the printhead are designed to enable the transport of the inkjet printing ink from the container to the printhead. [11] The container according to claim 10, wherein the means for connecting the container to a printhead comprise a printer and / or a filter and / or a pressure equalization vessel. [12] An inkjet printing system comprising: - the container according to one of claims 10 or 11; and - a printhead. [13] The inkjet printing system according to claim 12, further comprising at least one further container, wherein - the additional container contains another inkjet printing ink selected from the group consisting of a cyan inkjet printing ink, a yellow inkjet printing ink and a red inkjet printing ink; - the additional container comprises means for connecting the additional container to the printhead, wherein the means for connecting the additional container to the printhead are designed to transport the additional inkjet printing ink from the additional container to the printhead. [14] The inkjet printing system according to claim 12 or 13, further comprising a drying unit.