JP2010521330A - Inkjet printing method and inkjet ink set - Google Patents

Abstract

  Inkjet printing method comprising the following steps in sequence: a) preparing two or more color inkjet inks having the same color and color density but different compositions for an inkjet printer; b) preparing the two or more color inkjet inks Mixing in controlled amounts; c) printing a mixture of the two or more color inkjet inks on an ink receiver with an inkjet printer.

Description

  The present invention relates to an inkjet printing method and an inkjet ink set in which ink is ejected onto different types of ink receivers.

  In ink jet printing, ink fluid droplets are printed directly onto the ink receiver surface without physical contact between the printing device and the ink receiver. The printing device stores print data electronically and controls a mechanism for ejecting droplets according to the image. Printing is accomplished by moving the print head across the ink receptor and vice versa.

When jetting an inkjet ink onto an ink receptor, the ink generally comprises a liquid vehicle and one or more solids, such as a dye or pigment and a polymeric binder. It will be readily appreciated that the optimal composition of such inks will depend on the printing method used and the nature of the ink receiver to be printed. Ink compositions can be broadly classified as follows:
Water system, drying mechanism involves absorption, penetration and evaporation;
・ Solvent system, drying mainly involves evaporation;
Oil system, drying involves absorption and penetration;
Hot melt or phase change, ink is liquid at discharge temperature but solid at room temperature, drying is replaced by solidification;
UV curing, drying is replaced by polymerization.

  It is clear that the first three types of ink compositions are more suitable for a somewhat absorbent receiving medium, while hot melt inks and UV curable inks are usually printed on non-absorbing ink receivers. .

  However, it has been found that the behavior and interaction of UV curable inks on substantially non-absorbing ink receptors is very complex compared to water-based inks on absorbing ink receptors. In particular, good and controlled spreading of ink on the ink receiver has proven to be problematic and adhesion problems may be observed when using different types of non-absorbing ink receivers. The same problem was observed when solvent-based inkjet inks containing binders were jetted onto different types of non-absorbing ink receptors.

  One way to approach these problems is to develop and use different ink sets for different types of supports, but changing the printer ink and print head is extremely time consuming and industrial printing. This is not a preferred solution as it is not a really valuable solution for the environment. Therefore, a common approach is to modify the surface chemistry of the ink receiver with a suitable surface layer coating or by a pretreatment such as plasma or corona treatment.

  Corona discharge treatment and plasma treatment increase the cost, complexity and maintenance of the equipment used to treat the support. The support may contain significant impurities or irregularities that interfere with the processing of the support and thus do not result in uniform dispersion and adhesion of the ink.

  Other possibilities of using the same inkjet ink set on different ink receptors by application of the surface layer prior to jetting also increase the complexity of the inkjet printer. In general, the surface layer is coated and dried or cured prior to jetting the inkjet ink, as in the inkjet printing method of eg EP 1671805 A (AGFA) and US 2003021961 (3M), which is described in WO 00/30856 (XAAR). It is also possible to leave a wet uncured surface layer.

  However, a single composition of the surface layer suitable for all different supports is not available. WO 2006/111707 (SUN CHEMICAL) discloses an ink jet printing process in which i) a primer is applied to a support material; ii) the ink is ink jet printed on a primer-coated support; iii Iv) characteristics relating to print quality are evaluated; iv) the composition of the primer is adjusted depending on the evaluation characteristics related to print quality; and v) the adjusted primer composition is applied to the support material and the ink is a primer Inkjet printing on the coated substrate material gives the desired product. The surface layer substantially increases the thickness of the ink layer, which can result in a different appearance and reduced flexibility of the ink layer.

  Ink jet printing methods have also been investigated in which the ink jet ink is mixed with a colorless liquid or other color ink prior to jetting.

  US 6550892 (KODAK) Drops to deliver selectable color ink droplets to a receiver by mixing colorless liquid ink with liquid inks of different colors and delivering the ink mixture to the discharge chamber of the printhead. An on-demand inkjet printing system is disclosed. US 6050680 (CANON) relates to an ink jet recording apparatus capable of recording an image with a plurality of inks having different densities for each color by mixing a first ink containing a colorant and a second ink not containing a colorant.

  US 6097406 (KODAK) discloses an inkjet printing apparatus for printing continuous tone images in which a plurality of colorants or colorant precursors are mixed to produce the desired colorant.

  Instead of mixing colored inks, US Pat. No. 4,614,953 (LAITRAM) discloses a color inkjet printing mechanism that utilizes a single vapor stream of ink by jetting a solid dye into a carrier liquid to form a colored ink. The mechanism is capable of a wider range of tones than is possible using dither technology with three-color inks due to the premixing capability.

  US Pat. No. 5,854,642 (CANON) discloses an ink bottle containing inks having the same color and gives different compositions to the garment adapted to each type of fiber. The composition of ink varies depending on the type of colorant used.

  It would be desirable to be able to print inkjet inks with consistent image quality on a wide variety of ink receivers using conventional inkjet printers without requiring any complex or costly adaptation of the printer.

  Printing on a wide variety of different ink receivers, including non-absorbing substrates such as glass, metal or polymer surfaces, often results in inconsistent image quality and / or ink adhesion problems to the ink receiver Wake up. Changing the support often requires cumbersome changes to some processing of the inkjet ink set, the second inkjet printer, or the support, all of which are undesirable for productivity reasons.

  The object of the present invention is to use a wide variety of different types of ink jet printers using conventional inkjet printers without compromising on physical properties such as image quality consistency, adhesion of the image to the support, and productivity. To provide an ink jet ink set and an ink jet printing method capable of handling a support.

  Further objects of the present invention will become clear from the description below.

  Mixing inkjet ink with colorless liquids and color inks prior to jetting causes a change in colorant concentration due to less appropriate mixing, even if it does not consume time to adapt to inkjet printer color management, even if it does not consume time. Lead to quality differences.

  A wide variety of inks containing the same colorant at approximately the same concentration, but without the need to adjust the color management of the inkjet printer by mixing the rest, i.e. so-called ink carriers, with well-selected different compositions. It has been found that images can be produced that show the desired dispersion and / or adhesion and image quality for the support.

The object of the present invention is realized by an inkjet printing method comprising the following steps in order:
a) preparing two or more color inkjet inks having the same color and color density but different composition for an inkjet printer;
b) mixing the two or more color inkjet inks in controlled amounts; and c) printing the mixture of the two or more color inkjet inks on an ink receiver with an inkjet printer.

  The objects of the present invention are also realized in an inkjet ink set comprising two or more color inkjet inks having the same color and color density but different compositions.

  In radiation curable ink jet printing, the method of mixing color ink jet inks having the same color and color density has been advantageously used to obtain high cure speeds. The stability of color inkjet inks was improved by including a photoinitiator in one ink and a co-initiator in another color ink of the same color. By including high concentrations of photoinitiators and polymerization synergists in color inkjet inks of the same color and color density, inkjet ink mixtures that exhibit high cure speeds can be made.

Mixing two or more color inkjet inks of the same color and color density can be advantageously used for a number of purposes related to:
Image quality, eg dot size, gloss, line quality and blur;
Physical properties of the ink, such as viscosity, temperature, storage stability, surface tension, drying time, curing speed, adhesion to the support, flexibility and hardness of the ink layer; and jetting performance of the printer, such as Waiting time, nozzle plate pooling, flawed nozzles, droplet formation, and satellite formation.

  The difference in gloss between the ink-jet ink and the support typically leads to a lunar image quality. By mixing the appropriate color inks in appropriate proportions resulting in high or low gloss prints, the gloss of the inkjet ink can be matched to that of a particular support, which results in improved image quality. For a second support having a different gloss value, another ratio of ink jets having a high gloss value and ink jets having a low gloss value is then selected.

  Mixing two or more color inkjet inks of the same color and color density just prior to ejection can also be advantageously developed to include security features for security documents. Usually, the unmixed color ink is then mixed in a well selected ratio with another color ink containing a fluorescent compound, phosphorescent compound, thermochromic compound, iridescent compound or magnetic particles.

  The following figures are merely examples of possible configurations for mixing color inkjet inks of the same color and color density in or in an inkjet printer.

FIG. 1 shows a system for supplying a first ink “ink 1” to an inkjet printhead via a tube to which a second ink “ink 2” and subsequently a third ink “ink 3” are added in controlled amounts. FIG.

FIG. 2 is a schematic diagram of a system for supplying a first ink “ink 1” to an inkjet print head via a tube to which a second ink “ink 2” and a third ink “ink 3” are added in controlled amounts. It is.

FIG. 3 is a schematic diagram of a system for supplying a first ink “ink 1” and a second ink “ink 2” in controlled amounts to an ink mixing chamber, which then delivers the ink mixture to an inkjet printhead. It is.

FIG. 4 shows that the first ink “ink 1” and the second ink “ink 2” are supplied to the ink mixing chamber in controlled amounts, and then the ink mixing chamber controls the third ink “ink 3”. 1 is a schematic diagram of a system for delivering an ink mixture to an inkjet print head via a tube added at 1. FIG.

FIG. 5 shows a first ink “ink 1”, a second ink “ink 2”, and a third ink “ink 3” supplied in controlled amounts to an ink mixing chamber (not shown) included in the inkjet printhead. It is the schematic of the system which performs.

Definitions The term “inkjet ink set” as used in disclosing the present invention means an inkjet ink set that is coupled to an inkjet printer. It can be made, for example, from two separate commercially available CMYK inkjet ink sets, each containing four inkjet inks C, M, Y and K. However, it is necessary that the same color inkjet inks from both CMYK inkjet ink sets satisfy the conditions of the present invention. Alternatively, CC'MM'YY 'comprising two cyan inks C and C', two magenta inks M and M ', two yellow inks Y and Y' and two black inks K and K 'according to the present invention A KK ′ inkjet ink set can also be used.

  The term “colorant” as used in disclosing the present invention means dyes and pigments.

  The term “pigment” as used when disclosing the present invention means a colorant having a solubility of 10 mg / L or more under the ambient conditions involved in the medium to which it is applied.

  The term “pigment” is DIN 55943, incorporated herein by reference as a colorant which is actually insoluble in the application medium under the relevant ambient conditions and thus has a solubility of less than 10 mg / L in that application medium. Stipulated in

  The term “CI” used in disclosing the present invention is used as an abbreviation for color index.

  The term “UV” as used in disclosing the present invention is used as an abbreviation for ultraviolet light.

  The term “ultraviolet light” as used in disclosing the present invention means electromagnetic radiation in the wavelength range of 100 to 400 nanometers.

  The term “wt%” used in disclosing the present invention is used as an abbreviation for wt% based on the total weight of the ink unless otherwise specified.

  The term “actinic radiation” as used in disclosing the present invention means electromagnetic radiation capable of initiating a photochemical reaction.

  The term “Norish Type I initiator” as used in disclosing the present invention means an initiator that cleaves after excitation and immediately initiates a radical reaction.

  The term "Norish type II initiator" used when disclosing the present invention is an initiator that forms free radicals in an excited state by hydrogen abstraction or electron extraction from a second compound that actually becomes a free radical that initiates the reaction. Means. The second compound is referred to as a coinitiator or polymerization synergist. The synergist is a compound having a carbon atom and having at least one hydrogen atom at the α position with respect to the nitrogen atom.

  The term “photoacid generator” as used in disclosing the present invention means an initiator that generates acid or hemic acid when exposed to actinic radiation. Photoacid generators are also referred to as cationic initiators.

  The term “thermal initiator” as used in disclosing the present invention means an initiator that generates an initiator species upon exposure to heat.

  The term “alkyl” means all possible variations for each number of carbon atoms in an alkyl group, n-propyl and isopropyl for three carbon atoms, n- for four carbon atoms. By butyl, isobutyl and tertiary butyl, for 5 carbon atoms are meant n-pentyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 2-methyl-butyl and the like.

Inkjet printing method The inkjet printing method includes the following steps in order:
a) preparing two or more color inkjet inks having the same color and color density but different composition for an inkjet printer;
b) mixing the two or more color inkjet inks in controlled amounts;
c) Printing a mixture of the two or more color inkjet inks on an ink receiver with an inkjet printer.

  The possibility of adapting the ink mixture to a particular ink receptor increases with the number of color inkjet inks of the same color and color density present in the ink set, but the adhesion on different substrates and the consistency of image quality. Many problems can already be solved by using only two color inkjet inks of the same color and color density.

  In another embodiment, the inkjet ink set includes three color inkjet inks of the same color and color density to handle all the different supports.

  In the most preferred embodiment, the ink set includes two or more color inkjet inks of the same color and color density for each of the colors, e.g. cyan, magenta, yellow and black colors, where the different color inks are solids and Has a corresponding composition of liquid components. For example, except for the colorant, the same solids and solvent of the first yellow ink can be found in approximately the same amount in the corresponding first cyan ink, while the different solids and solvent of the second yellow ink correspond. It is found in about the same amount as the second cyan ink.

  In another embodiment, the inkjet printing method includes two or more color inkjet inks of the same color and color density, and two or more color inkjet inks of the same color but lower color density, so-called “multi-density” "Use an inkjet ink set." For example, an ink set may include two or more “dark magenta” inkjet inks of the same color density, and two or more “light magenta” inkjet inks of the same color density but smaller than the color density of the “dark magenta” inkjet ink. May be included. In another preferred embodiment, the multi-density inkjet ink set includes dark and light inkjet inks for magenta and cyan colors. Dark black and light black inks may also be present in the inkjet ink set.

  The ink jet printing method according to the present invention preferably uses an ink jet ink set in which two or more color ink jet inks of the same color but of a lower color density contain the same type of colorant. Most preferably, the colorants are the same.

  In the inkjet printing method according to the present invention, it is preferred that the colorant in two or more color inkjet inks be present in exactly the same amount, but small variations in density when manufacturing inkjet inks can be tolerated. Most preferably, the amount of colorant in the first ink of the two or more color inkjet inks is the amount of colorant in the second inkjet ink of the two or more color inkjet inks and the colorant in the first ink. Preferably 10 wt% or less, more preferably 5 wt% or less.

Table 1 gives how become one of the described magenta and cyan inks in a solvent based inkjet ink set. All magenta inks contain the same magenta pigment and polymer dispersant in amounts of 4.0 wt%, respectively, based on the total weight of the ink. All solvent mixtures contain the same amount of the same solvent 1, which could be the result of a method of making an inkjet ink. Typically, first, a concentrated pigment dispersion is prepared using one or more dispersion solvents (here a single dispersion solvent “Solvent 1” is used), which is then one or more ink solvents. (Here solvent 2-4) and other compounds such as surfactants, stabilizers and the like. Ink solvents 2-4 are present or not present at different concentrations in the three magenta inks A, B and C. Nearly the same mixture of solvents 1 to 4 is used for the corresponding three cyan inks D, E and F. For example, cyan ink D matches magenta ink A. When a particular ink receiver is selected, the magenta inks A, B and C will be mixed together in a certain ratio: the same ratio is usually determined by the adhesive properties of the magenta ink mixture and the cyan ink mixture, for example, the specific support. It will be used to mix the corresponding inks D, E and F to be more or less the same above.

  In one embodiment, the ink set includes two color inkjet inks of the same color and color density, where the first color inkjet ink includes a large amount of one or more surfactants and the second color inkjet ink Differ only in the absence of surfactant or the inclusion of small amounts of one or more surfactants. Any desired surface tension of the ink mixture can be obtained by mixing the two color inkjet inks in the ink supply system. Provided that suitable surfactants are selected and that they are present in a sufficiently high amount in the first color inkjet ink to encompass the full range of desired surface tension. By controlling the surface tension, the printer can obtain the same dispersion characteristics on ink receivers with different surface energies.

In a preferred embodiment, both adhesion and surface tension are controlled by mixing the inks in a certain ratio. Table 2 illustrates this for an inkjet ink set containing four magenta inks. In this case, the surfactant is added to the ink D. Ink D is consistent with Ink B except for the amount of solvents 3 and 4 that compensate for the addition of surfactant and make the necessary modifications to keep the magenta pigment concentration constant. In an ink mixture with inks A, B and C optimized for adhesion on a particular substrate, the amount of ink B does not change the adhesion properties but achieves the desired ink dispersion properties on the substrate. In order to do so, the ink mixture can be replaced by ink D by adapting it to a specific surface tension. The choice for ink B can be given by the fact that ink B is most frequently used in large quantities in the ink mixture. Another option may be to include a small amount of surfactant in inks A and / or C and use ink D to “fine tune” the surface tension of the ink mixture.

The ink jet printing method according to the present invention can also be advantageously used in combination with radiation curable ink jet inks to improve dispersion stability and / or cure speed. This is illustrated by Table 3 , where Ink A contains a photoinitiator and polymerization inhibitor but no polymerization synergist, while Ink B contains this active synergist but no photoinitiator. Both inks show very good storage stability, but can show poor stability due to the rapidly induced polymerization once mixed. Mixing these inks immediately before jetting can be advantageously used to obtain a high cure speed.

Same Color and Color Density In the present invention, the following procedure was used to determine whether two inks had the same color and density.

  Starting from the ink formulation used in the printer, a 1: 1000 mass dilution was prepared. Obviously, the solvent for dilution must be compatible with the ink dispersion. That is, the solvent should be selected so that chemical and physical stability is maintained. This is because otherwise additional light scattering can occur, for example color changes due to particle aggregation. Preferably, the diluent solvent is selected from one or more liquid components of the ink. In the examples given below, DPDGA was used as the diluent solvent.

  A transmission measurement τ was collected from the diluted ink dispersion with a spectrophotometer. Measurements were based on the geometry of direct illumination and extensive integration detection. An example of such a spectrophotometer is a double beam spectrophotometer from Perkin Elmer that implements a measurement geometry τ (8 / d) according to ASTM E179-96.

A quartz cuvette with a 10 mm optical path was filled with diluted ink and then placed in contact with the inlet of the integrating sphere. For reference measurements, the same quartz cuvette filled with undiluted solvent was used. The transmission spectrum of the diluted ink was divided by the transmission spectrum of the reference measurement to correct for the dilution solvent and the quartz cuvette. The CIE ^L * ^a * ^{b *} coordinates from these spectra were calculated according to ASTM E308-01 based on the CIE 1931 standard observer (2 deg) and D50 light source. The CIE ΔE2000 color difference was calculated from the CIE L ^* a ^* b ^* coordinates with a set of industry-dependent parameters K _L , K _C and K _H that would be 1.

  In light of the ink jet printing application field for which the present invention is intended, two inks A and B should yield CIE ΔE2000> 5.0 for a given observer and light source (ie, no spectral matching is required). Are considered to have different colors and densities. If the color difference CIE ΔE2000 between Ink A and Ink B is greater than 5.0, a new characterization of the inkjet printing system with respect to color management is generally required, while a difference less than 2.0 is a new linear only for the printer Can be compensated for by In that sense, two inks A and B having a pair of color differences CIE ΔE2000 less than or equal to 2.0 are considered to have the same color and density.

  For demanding printing applications, a color difference CIE ΔE2000 of less than or equal to 1.5 is required for the same color and density. In an even more restrictive colorimetric approach, the same color and density is achieved if the color difference CIE ΔE2000 is less than or equal to 1.0.

References • ASTM D2244-02 Standard Practice for Calculation of Color Tolerances and Color Differentiated from Instrumental Color Coordinates
ASTM E179-96 (2003) Standard Guide for Selection of Geometric Conditions for Measurements of Reflections and Transmission Properties of Materials
ASTM E308-01 Standard Practicing for Computing the Colors of Objects by Using the CIE system

Inkjet Printer & Ink Supply System Industrial inkjet printers typically include an ink supply system for supplying ink to an inkjet printhead. Inkjet printheads form droplets either continuously or on demand. “Continuous” means that a continuous stream of ink droplets is created, for example, by pressurizing the ink supply. “On demand” differs from “continuous” in that ink droplets are ejected from the print head only by a physical operation that instantaneously overcomes the surface tension that holds the ink in the print head. The ink is held in a nozzle that forms a meniscus. The ink remains in place unless there is some other force that overcomes the surface tension inherent in the liquid. The most common method is to suddenly increase the pressure on the ink and eject the ink from the nozzles. One category of drop-on-demand ink jet printheads uses the physical phenomenon of electrostriction, the change in transducer dimensions in response to an applied electric field. Electrostriction is strongest in piezoelectric materials, so these printheads are referred to as piezoelectric printheads. This very small dimensional change of the piezoelectric material is exploited over a large area to generate a volume change large enough to squeeze the ink droplets out of the small chamber. Piezoelectric print heads include a number of small ink chambers arranged in a row, each deformable to produce the volume changes necessary to eject ink droplets from the nozzles according to the principle of individual nozzles and electrostriction With wall area.

  In a preferred embodiment, the ink jet printer is a drop on demand ink jet printing system having a piezoelectric print head for delivering a drop of a selectable color ink mixture to an ink receiver.

  Inkjet ink is supplied to the ink ejection chamber of the printhead by an ink supply system that first conditions the ink to obtain a smooth operation of the inkjet printhead. Conditioning includes, for example, degassing ink and controlling back pressure at the nozzle.

  It is known that the presence of bubbles in the ink chamber of a piezoelectric print head often causes malfunctions of the print head. If air is present in the ink chamber, the intended pressure change resulting from piezoelectric deformation of a portion of the ink chamber wall will be absorbed by the air and the ink pressure will not be affected. The ink surface tension in the nozzle will maintain a meniscus and no droplets will be ejected from the ink chamber. At the frequency (in the range of kHz to MHz) at which the piezoelectric transducer in the piezoelectric print head is operated, not only bubbles in the ink but also dissolved air can cause the above-mentioned operation failure. The prior art discloses a concept for avoiding air bubbles in the ink chamber by creating an air trap upstream of the ink chamber (ie, before the ink enters the ink chamber). Solutions in the form of air interferometers or gas separators that allow air bubbles to float and be discharged from the ink in an intermediate tank before the ink is supplied to the print head are described in EP 71479A (CANON) and US 4929963 (HP). Has been proposed in

  The second consideration of the ink supply system is the pressure at the nozzle, which is important for well-regulated and well-operated print heads. Inkjet printheads perform best with slightly negative nozzle pressure or back pressure. In practice, this is often accomplished by maintaining a height difference between the free ink surface in the vented ink supply system and the meniscus at the nozzle. That is, the free ink surface in the vented supply tank is maintained gravimetrically at 2 centimeters below the meniscus level at the nozzle. This height difference established the hydrostatic pressure difference to control the back pressure in the nozzle. The ink supply tank is located off-axis when reciprocating the print head configuration. That is, no scanning is performed. This is because the lower position of the ink supply tank relative to the print head otherwise obstructs the print medium transport path. For example, as disclosed in US 4929963 (HP), a flexible tube is used to connect an off-axis ink supply tank with an on-axis print head. During print head acceleration and deceleration, pressure waves are created in the tube that can significantly disturb the meniscus pressure balance, leading to nozzle leaching in the case of a negative pressure decrease or in the case of a negative pressure increase. Can lead to the destruction of air and the incorporation of air into the ink flow path. Many approaches have been proposed to control back pressure in reciprocating printhead applications. Back pressure adjustment mechanisms in the form of pressure dampers or dampers mounted with a print head on a reciprocating carriage are disclosed in EP 1120257 A (SEIKO EPSON) and US 6485137 (APRION DIGITAL). The response time of these devices is insufficient for accelerating and decelerating carriages above 1G. In EP 1142713 A (SEIKO EPSON), a vented subtank is used. The sub tank acts as a local ink reservoir near the print head and is filled intermittently from the main tank located off-axis. The solution provides good control of nozzle back pressure by maintaining a local static pressure difference between the free ink surface of the vented sub-tank and the meniscus.

Ink mixing means As long as the means for mixing the ink is made of a material that is compatible with the ink (eg, solvent resistant material when solvent-based inkjet inks are to be mixed), there are practical limitations to their choice There is no.

  The ink can be mixed at various locations on the inkjet printer, for example directly at the first connection of the inkjet ink to the inkjet printer, near the inkjet print head or even inside the print head. The smaller the distance between the ink mixing location and the print head nozzle, the less ink will spill to accommodate the new ink receiver being printed.

  In one preferred embodiment, the ink mixing means has a compact design so that it can be included in a carriage that includes an assembly of print heads that move back and forth along the fast scan direction.

  Preferably, an ink mixing means that does not introduce bubbles into the ink mixture is selected.

  Although not required to obtain a consistent image quality in the color gamut, preferably an ink mixing means is selected in which the ink is thoroughly mixed properly.

  For some ink-jet inks, such as dye-based inks, the ink mixing means may simply consist of multiple conduits that go together in a single conduit, which is a number of sharp bends to mix the ink. Or make a V bend.

  More complex ink mixing means may include pumps, valves, mixing chambers and the like.

  If necessary, ink mixing may be performed with cooling to prevent heat build-up. For radiation curable inks, ink mixing is performed as much as possible under light conditions where actinic radiation is substantially excluded.

  In one embodiment, two or more color inkjet inks of the same color and color density are fed through a conduit to the inkjet printhead where the ink mixture is made in situ with the conduit. A flow controller is adapted to selectively meter ink from two or more color inkjet ink sources into a conduit between one color inkjet ink source and the printhead ejection chamber. The ink supply system according to this embodiment is illustrated by FIGS.

  In another embodiment, the ink supply system includes an ink mixing chamber in which two or more color inkjet inks of the same color and color density are first mixed in a controlled amount before delivering the ink mixture to the printhead. . The ink supply system according to this embodiment is illustrated by FIG.

  The two previous embodiments also control at least three color inkjet inks of the same color and color density partly in the ink mixing chamber and partly in the conduit between the ink mixing chamber and the print head. Can be combined to provide an ink supply system that is mixed in different amounts. The ink supply system according to this embodiment is illustrated by FIG.

  In another embodiment, a controlled amount of mixing of two or more color inkjet inks of the same color and color density occurs in the printhead. The ink supply system according to this embodiment is illustrated by FIG.

  Although (part of) the ink mixing system can be located within the print head, it is preferred that the ink mixing system be separated from the print head. This allows the connection of the ink supply system to a wide range of already commercially available print heads and inkjet printers, and thus does not increase the complexity and development cost of the print head. Furthermore, maintenance is much easier with an ink mixing system that is not located in the print head, for example when ink agglomeration occurs.

  It is clear that for each ink set there is a mixing means for each color, whereas there are preferably two or more color inkjet inks of the same color and color density in the inkjet ink set.

Computing means In a preferred embodiment, the ink supply system is connected to a computer for controlling the ink mixing process. This may include opening and closing valves, pump flow control, stirrer rotational speed and other mechanical configurations to obtain the desired ink mixture. However, the computer is also preferably used to store and recall data for the ink mixture used on a particular ink receiver. This allows fast adjustment of the inkjet printer to a specific ink receptor that has already been printed with the same inkjet ink set in the past.

  In another embodiment, the computer allows the selection of different ink mixtures on a previously unused ink receiver that allows the selection of ink mixtures that exhibit desired properties such as image quality, adhesion, etc. after inspection of the printed pattern. It may be used to generate a test pattern. Using this method, where a new support is used as an ink receiver each time, a digital library of ink mixing data for a particular ink receiver is generated. This ink blend data includes the ratio of inkjet ink and its relationship to image quality and physical properties. The use of libraries, more preferably digital libraries, leads to increased productivity.

  For a number of characteristic properties, it differs by including downstream means of the printer that can measure or evaluate line width, edge linearity, spots, print density, gloss and / or color intensity. The evaluation of the test pattern of the ink mixture can be automated.

Inkjet Ink Receptor Suitable ink receivers for the inkjet printing method according to the present invention are not limited to any particular type and can be transparent, translucent or opaque. The ink receiver may be colored or metallized. It can be a temporary support for transferring the image to another support after printing, for example. Applications such as direct printing on wooden doors, panels and ceramics and 3D printing are also within the scope of the present invention.

  Aqueous inks are generally printed on an absorbent ink receptor. Solvent-based inkjet inks and radiation curable inks can also be printed on receivers that are substantially non-ink-absorbing to aqueous solutions. For example, standard paper is an ink-absorbing receiver. On the other hand, resin-coated paper, such as polyethylene-coated paper or polypropylene-coated paper, is usually substantially non-absorbent.

  The ink receiver may include a support having at least one ink receiving layer. The ink receiver may consist of only one layer, or it may be composed of two, three or more layers. The ink receiving layer may contain one or more polymer binders and optionally fillers. Ink-receiving layers and optional auxiliary layers (for example, anti-curl and / or backing layers for adhesion purposes) are also well known conventional ingredients such as surfactants, crosslinkers, plasticizers that act as coating aids. , Cationic substances acting as mordants, light stabilizers, pH adjusters, antistatic agents, biocides, lubricants, whitening agents and matting agents.

  The ink receiving layer and optional auxiliary layers may be crosslinked to some extent to provide desired characteristics such as water resistance and non-blocking properties. Crosslinking is also useful to provide resistance and abrasion resistance to the formation of fingerprints on the element as a result of handling.

  Suitable supports for the ink receiving layer are those suitable for solvent-based inkjet inks or radiation curable inks, such as polymer supports such as cellulose acetate propionate, cellulose acetate butyrate, polyethylene terephthalate. Polyesters such as (PET) and polyethylene naphthalate (PEN), oriented polystyrene (OPS), oriented nylon (ONy), polypropylene (PP), oriented polypropylene (OPP), polyvinyl chloride (PVC), and various polyamides, Includes extruded blends of polycarbonate, polyimide, polyolefin, poly (vinyl acetal), polyether and polysulfonamide, opaque white polyester, and polyethylene terephthalate and polypropylene. Acrylic resins, phenolic resins, glass and metals may also be used as ink receivers. Other suitable ink receiver materials are Modern Approaches to Wetability: Theory and Applications. Edited by SCRADER, Malcolm E. et al. , Et al. New York: Plenum Press, 1992. Can be found in ISBN 03064339859.

The ink receiver may also contain mineral particles as a filler, for example CaCO ₃ containing PET, TiO ₂ containing PET, amorphous PET (APET) and glycolated PET (PETG).

  The ink receiver may be provided with a self-adhesive backing layer. Examples of self-adhesive PVC ink receptors are MPI ™ vinyl from AVERY-DENNISON, Digital ™ vinyl from METAMARK, Multi-fix ™ digital white vinyl from MULTI-FIX, and Grafiprint from GRAFITYP. (Trademark) Contains vinyl.

  Polyester film supports, especially polyethylene terephthalate, are preferred for certain applications, particularly for types with excellent dimensional stability. When such polyester is used as an ink receiver, a subbing layer may be used to improve the adhesion of the jetted ink layer to the support (if it is substantially non-absorbing with an unprimed support). If it constitutes a sex ink receiver). Useful subbing layers for this purpose are well known in the photographic art and include, for example, vinylidene chloride polymers such as vinylidene chloride / acrylonitrile / acrylic acid terpolymers or vinylidene chloride / methyl acrylate / itaconic acid terpolymers. Modifiers for physical film properties such as stabilizers, smoothing additives, matting agents, waxes may also be added to the subbing layer if necessary.

  The ink receiving layer may also be made from inorganic materials such as metal oxides or metals (eg, aluminum and steel).

  Other suitable ink receivers may be selected from the group consisting of cardboard, wood, composite board, coated plastic, canvas, woven fabric, glass, vegetable fiber products, leather, magnetic materials and ceramics.

Inkjet Ink Set The inkjet ink set according to the present invention comprises two or more color inkjet inks having the same color and color density but containing different solid and / or liquid components.

  In a preferred embodiment, the two or more color inkjet inks contain the same colorant. Preferably, the amount of each colorant in the first ink of the two or more color inkjet inks is 10 wt% or less with respect to the amount of the colorant in the second inkjet ink of the two or more color inkjet inks, More preferably 5 wt% or less, most preferably 2 wt% or less (all based on the total weight of the colorant in the first ink). Most preferably, the color pigment is present in the same amount in each of the two or more color inkjet inks.

  In one embodiment, the two or more color inkjet inks contain different amounts of surfactants and / or different types of surfactants.

  In a preferred embodiment, the two or more color inkjet inks are solvent-based inkjet inks.

  In another preferred embodiment, the two or more color inkjet inks are radiation curable inkjet inks.

  In a further preferred embodiment of the radiation curable inkjet ink, a photoinitiator is present in at least one of the two or more radiation curable color inkjet inks and at least one of the two or more radiation curable color inkjet inks. Do not exist in one other ink. In a more preferred embodiment, the coinitiator or polymerization synergist is present in at least one of the two or more color inkjet inks that do not include a photoinitiator. In another more preferred embodiment, the inhibitor is present in at least one of the two or more color inkjet inks containing a photoinitiator.

  In another embodiment, the inkjet ink set may further include two or more colorless inkjet inks that include different solid and / or liquid components. These colorless inkjet inks may be used, for example, to reduce or enhance the gloss of the image in the topcoat layer. The topcoat layer can also be applied to enhance the solvent resistance or durability of the image or to reduce the amount of extract when printed on food packaging materials.

  An inkjet ink set in an inkjet printer may include two or more color inkjet inks of the same color and color density in different volumes. Sometimes one ink is consumed much faster than the other. For example, other inks are directed to good adhesion on a less frequently used support. In particular, because of the limited shelf life given to radiation curable inks, ink waste and the cost allocated to it can be reduced.

Inkjet ink The inkjet ink in the ink set according to the present invention is preferably a non-aqueous inkjet ink. In non-aqueous inkjet inks, the components are present in a dispersion medium that is a non-aqueous liquid at the jetting temperature.

  The term “non-aqueous liquid” refers to a liquid carrier that does not contain any water. However, small amounts, typically less than 5 wt% water, can be present, based on the total weight of the ink. This water was not intentionally added, but was included in the formulation as a contamination via other ingredients such as polar organic solvents. An amount of water greater than 5 wt% destabilizes the non-aqueous inkjet ink, preferably the water content is less than 1 wt% based on the total weight dispersion medium, and most preferably no water is present.

  The two or more color inkjet inks of the inkjet ink set according to the present invention preferably contain a pigment as a colorant. If the colorant is not a self-dispersing pigment, the ink-jet ink also preferably contains a dispersant, more preferably a polymer dispersant.

  The inkjet ink of the ink set according to the present invention may further contain at least one surfactant.

  The ink-jet ink of the ink set according to the present invention may contain at least one humectant to prevent nozzle clogging due to its ability to reduce the evaporation rate of the ink.

  The colored color inkjet ink according to the present invention may contain at least one dispersion synergist. Mixtures of dispersion synergists may be used to further improve dispersion stability.

  The inkjet ink of the ink set according to the present invention is preferably an inkjet ink selected from the group consisting of organic solvent-based, oil-based and curable inkjet inks. The curable inkjet ink is preferably radiation curable.

The viscosity of the inkjet ink is 100 ^{mPa.s at} a shear rate of 100 s ⁻¹ and 30 ° C. It is preferably smaller than s. The viscosity of the inkjet ink is preferably 30 mPa.s at a shear rate of 100 s ⁻¹ and a jetting temperature of 10 to 70 ° C. s, more preferably 15 mPa.s. s, most preferably 2 to 10 mPa.s. s.

  The curable inkjet ink may contain monomers, oligomers and / or prepolymers having different functionalities as the dispersion medium. Mixtures containing combinations of mono-, di-, tri- and / or higher functionality monomers, oligomers or prepolymers may be used. A catalyst called an initiator for initiating the polymerization reaction may be included in the curable inkjet ink. The initiator can be a thermal initiator, but is preferably a photoinitiator. Photoinitiators require less energy for activation than monomers, oligomers and / or prepolymers to form polymers. Suitable photoinitiators for use in the curable pigment dispersion may be Norrish type I initiators, Norrish type II initiators or photoacid generators.

  The curable inkjet ink of the ink set according to the present invention may further contain at least one inhibitor.

  The CMYK inkjet ink set may also be spread with one or more extra inks such as red, green, blue and orange to further expand the color gamut of the image. The CMYK ink set may also be extended with a combination of strong and light densities of both color and / or black ink to improve image quality by reducing graininess.

Colorant The two or more color inkjet inks of the inkjet ink set according to the present invention contain at least one colorant. The colorant used in the inkjet ink may be a pigment, a dye, or a combination thereof. Organic and / or inorganic pigments may be used.

  Two or more radiation curable inkjet inks or solvent-based inkjet inks preferably contain a pigment as a colorant.

  The pigment in the inkjet ink may be black, cyan, magenta, yellow, red, orange, purple, blue, green, brown, a mixture thereof, and the like.

  Color pigments are described in HERBST, Willy, et al. Industrial Organic Pigments, Production, Properties, Applications. 3rd edition. Wiley-VCH, 2004. It may be selected from those disclosed by ISBN 3523055769.

  Suitable pigments are C.I. I. Pigment Yellow 1,3,10,12,13,14,17,55,65,73,74,75,83,93,97,109,111,120,128,138,139,150,151,154 155, 180, 185 and 213.

  Particularly preferred pigments are C.I. I. Pigment Yellow 120, 151, 154, 175, 180, 181 and 194.

  The most preferred yellow pigment is C.I. I. Pigment Yellow 120, 139, 150, 155, and 213.

  Particularly preferred pigments are C.I. I. Pigment Red 17, 22, 23, 41, 48: 1, 48: 2, 49: 1, 49: 2, 52: 1, 57: 1, 81: 1, 81: 3, 88, 112, 122, 144, 146, 149, 169, 170, 175, 176, 184, 185, 188, 202, 206, 207, 210, 216, 221, 248, 251, 254, 255, 264, 270 and 272. Most preferred for producing a decorative laminate is C.I. I. Pigment Red 254 and C.I. I. Pigment Red 266. The most preferred pigments for other non-aqueous inkjet applications are C.I. I. Pigment Red 122 and C.I. I. Pigment Violet 19.

  Particularly preferred pigments are C.I. I. Pigment Violet 1, 2, 19, 23, 32, 37, and 39.

  Particularly preferred pigments are C.I. I. Pigment Blue 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 56, 61 and (crosslinked) aluminum phthalocyanine pigments.

  Particularly preferred pigments are C.I. I. Pigment Orange 5, 13, 16, 34, 40, 43, 59, 66, 67, 69, 71 and 73.

  Particularly preferred pigments are C.I. I. Pigment Green 7 and 36.

  Particularly preferred pigments are C.I. I. Pigment Brown 6 and 7.

  Suitable pigments include mixed crystals of the above particularly preferred pigments. A commercially available example is Cinquasia Magenta RT-355-D from Ciba Specialty Chemicals.

  Carbon black is preferred as a pigment for black inkjet inks. Suitable black pigment materials include Pigment Black 7 (eg Carbon Black MA8® from MITSUBISHI CHEMICAL), Regal® 400R, Mogul® L, Elftex® 320 from CABOT Co, or Carbon Black FW18, Special Black 250, Special Black 350, Special Black 550, Printex (registered trademark) 25, Printex (registered trademark) 35, Printex (registered trademark) 55, Printex registered trademark 55, Printex (registered trademark) 55, Printex registered trademark 55 Including carbon black such as 150T. Additional examples of suitable pigments are disclosed in US 5,389,133 (XEROX).

  It is also possible to make a mixture of pigments in two or more color inkjet inks. For certain applications, neutral black inkjet inks are preferred and can be obtained, for example, by mixing black and cyan pigments into the ink. Inkjet applications may require one or more spot colors, for example for packaging inkjet printing or textile inkjet printing. Silver and gold are often desirable colors for inkjet poster printing and point of sale displays.

  Non-organic pigments may also be present in two or more color inkjet inks. Particularly preferred pigments are C.I. I. Pigment Metal 1, 2 and 3. Examples of inorganic pigments are titanium oxide, barium sulfate, calcium carbonate, zinc oxide, lead sulfate, yellow lead, zinc yellow, petal, cadmium red, ultramarine blue, Prussian blue, chromium oxide green, cobalt green, agate, titanium black And synthetic iron black.

  In general, the pigment is stabilized in the dispersion medium by a dispersant such as a polymeric dispersant or surfactant. However, the surface of the pigment can be modified to obtain so-called “self-dispersible” or “self-dispersing” pigments, ie pigments that can be dispersed in a dispersion medium without a dispersant.

  The pigment particles in the inkjet ink should be small enough to allow free flow of ink through the inkjet printing device, particularly at the jet nozzle. It is also desirable to use small particles for maximum color intensity and slow settling.

  The number average pigment particle size is preferably 0.050 to 1 μm, more preferably 0.070 to 0.300 μm, and particularly preferably 0.080 to 0.200 μm. Most preferably, the number average pigment particle size is 0.150 μm or less. However, for example, the average pigment particle size for a white inkjet ink containing a titanium dioxide pigment is preferably 0.100 to 0.300 μm.

  The pigment is preferably used for pigment dispersion used to make inkjet inks in an amount of 10-40 wt%, preferably 15-30 wt%, based on the total weight of the pigment dispersion. In the inkjet ink, the pigment is preferably used in an amount of 0.1 to 20 wt%, preferably 1 to 10 wt%, based on the total weight of the inkjet ink.

  Dyes suitable for two or more color inkjet inks in the ink set according to the present invention include direct dyes, acidic dyes, basic dyes and reactive dyes.

Suitable direct dyes for two or more color inkjet inks include:
・ C. I. Direct Yellow 1, 4, 8, 11, 12, 24, 26, 27, 28, 33, 39, 44, 50, 58, 85, 86, 100, 110, 120, 132, 142, and 144
・ C. I. Direct Red 1, 2, 4, 9, 11, 134, 17, 20, 23, 24, 28, 31, 33, 37, 39, 44, 47, 48, 51, 62, 63, 75, 79, 80, 81, 83, 89, 90, 94, 95, 99, 220, 224, 227 and 343
・ C. I. Direct Blue 1, 2, 6, 8, 15, 22, 25, 71, 76, 78, 80, 86, 87, 90, 98, 106, 108, 120, 123, 163, 165, 192, 193, 194 195, 196, 199, 200, 201, 202, 203, 207, 236, and 237
・ C. I. Direct Black 2, 3, 7, 17, 19, 22, 32, 38, 51, 56, 62, 71, 74, 75, 77, 105, 108, 112, 117, 154 and 195

Suitable acidic dyes for two or more color inkjet inks include:
・ C. I. Acid Yellow 2, 3, 7, 17, 19, 23, 25, 20, 38, 42, 49, 59, 61, 72, and 99
・ C. I. Acid Orange 56 and 64
・ C. I. Acid Red 1,8,14,18,26,32,37,42,52,57,72,74,80,87,115,119,131,133,134,143,154,186,249,254 And 256
・ C. I. Acid Violet 11, 34, and 75
・ C. I. Acid Blue 1,7,9,29,87,126,138,171,175,183,234,236, and 249
・ C. I. Acid Green 9, 12, 19, 27, and 41
・ C. I. Acid Black 1, 2, 7, 24, 26, 48, 52, 58, 60, 94, 107, 109, 110, 119, 131, and 155

Suitable reactive dyes for two or more color inkjet inks include:
・ C. I. Reactive Yellow 1, 2, 3, 14, 15, 17, 37, 42, 76, 95, 168, and 175
・ C. I. Reactive Red 2, 6, 11, 21, 22, 23, 24, 33, 45, 111, 112, 114, 180, 218, 226, 228, and 235
・ C. I. Reactive Blue 7, 14, 15, 18, 19, 19, 21, 25, 38, 49, 72, 77, 176, 203, 220, 230, and 235
・ C. I. Reactive Orange 5, 12, 13, 35, and 95
・ C. I. Reactive Brown 7, 11, 33, 37, and 46
・ C. I. Reactive Green 8 and 19
・ C. I. Reactive Violet 2, 4, 6, 8, 21, 22, and 25
・ C. I. Reactive Black 5, 8, 31, and 39

Suitable basic dyes for two or more color inkjet inks include:
・ C. I. Basic Yellow 11, 14, 21, and 32
・ C. I. Basic Red 1, 2, 9, 12, and 13
・ C. I. Basic Violet 3, 7, and 14
・ C. I. Basic Blue 3, 9, 24, and 25

  If the color ink-jet ink contains water, the dye can manifest the ideal color only in the appropriate range of pH. Therefore, it is preferable that the inkjet ink further includes a pH adjusting agent.

Suitable pH adjusters include NaOH, KOH, NEt ₃ , NH ₃ , HCl, HNO ₃ , H ₂ SO ₄ and (poly) alkanolamines such as triethanolamine and 2-amino-2-methyl-1-propaniol. . Preferred pH adjusters are NaOH and H ₂ SO ₄ .

  The dye is used in two or more color inkjet inks in an amount of 0.1-30 wt%, preferably 1-20 wt%, based on the total weight of the inkjet ink.

  In certain embodiments, the colorant is a fluorescent colorant used to introduce security features. Suitable examples of fluorescent colorants include Tinopal (R) grades such as Tinopal (R) SFD, Uvitex (R) grades such as Uvitex (R) NFW and Uvitex (R) OB (all CIBA SPECIALTY Available from CHEMICALS); Leukophor® grades from CLARIANT and Brancophor® grades such as Blankophor® REU and Blancophor® BSU from BAYER.

Dispersants A typical polymer dispersant is a copolymer of two monomers, but may contain three, four, five or more monomers. The properties of polymer dispersants depend on both the nature of the monomers and their distribution in the polymer. Suitable copolymer dispersants have the following polymer composition:
A randomly polymerized monomer (eg, monomers A and B are polymerized to ABBAABAB);
Alternating monomers (eg monomers A and B polymerized to ABABABAB);
Gradient (gradually) polymerized monomers (eg, monomers A and B are polymerized to AAABAABBABBB);
Block copolymers (eg polymerizing monomers A and B into AAAAABBBBBBBB) where the block length of each of the blocks (2, 3, 4, 5 or more) is relative to the dispersing capacity of the polymer dispersant Important;
A graft copolymer (the graft copolymer consists of a polymer backbone with side chains attached to the backbone); and a mixed form of these polymers, eg a blocky gradient copolymer.

  The polymeric dispersant may have a variety of polymer configurations including linear, comb / branched, star-like, dendritic (including dendrimers and hyperbranched polymers). A general overview of polymer structure can be found in ODIAN, George, Principles of Polymerization, 4th edition, Wiley-Interscience, 2004, p. 1-18.

  Comb / branched polymers have side branches of linked monomer molecules that protrude from various central branch points (at least three branch points) along the main polymer chain.

  A star polymer is a branched polymer in which three or more similar or different linear homopolymers or copolymers are bonded together in a single core.

  Dendritic polymers include dendrimer and hyperbranched polymer types. For dendrimers with a well-defined monodisperse structure, all branch points are used (multistage synthesis), while hyperbranched polymers lead to further branching with multiple branch points and polymer growth (single stage polymerization process) Has multi-functional branching.

  Suitable polymeric dispersants may be made by addition or condensation type polymerization. The polymerization method is described in ODIAN, George, Principles of Polymerization, 4th edition, Wiley-Interscience, 2004, p. Including those described in 39-606.

Addition polymerization methods include free radical polymerization (FRP) and controlled polymerization techniques. Suitable controlled radical polymerization methods include the following:
RAFT: reversible addition-breaking chain transfer;
ATRP: atom transfer radical polymerization;
MADIX: reversible addition-fragmentation chain transfer method using transfer active xanthate;
-Catalytic chain transfer (eg using cobalt complexes);
Nitroxide (eg TEMPO) mediated polymerization.

Other suitable controlled polymerization methods include the following:
GTP: group transfer polymerization;
-Living cationic (ring-opening) polymerization;
Anion coordination insertion ring-opening polymerization; and Living anion (ring-opening) polymerization.

  Reversible unbreakable transfer (RAFT): Controlled polymerization occurs via rapid chain transfer between growing polymer radicals and dormant polymer chains. A review paper on RAFT synthesis of dispersants with various polymer geometries is available from QUINN J. F. et al. , Face Synthesis of comb, star, and graft polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization, Journal of Polymer. 40, 2956-2966, 2002.

  Group Transfer Polymerization (GTP): The method of GTP used for the synthesis of AB block copolymers is described in SPINELLI, Harry J, GTP and its uses in water pigment dispersants and emulsion stabilizers, Proc. of 20th Int. . Conf. Org. Coat. Sci. Technol. , New Platz, N .; Y. , State Univ. N. Y. , Inst. Mater. Sci. p. 511-518.

  The synthesis of dendritic polymers is described in the literature: The synthesis of dendrimers in NEWCOME, G. R. , Et al. Dendritic Molecules: Concepts, Synthesis, Perspectives. VCH: WEINHEIM, 2001. Hyperbranched polymerization is described by BURCHARD, W. et al. . Solution properties of branched macromolecules. Advances in Polymer Science. 1999, vol. 143, no. II, p. 113-194. Hyperbranched materials are Fluory, P .; J. et al. . Molecular size distribution in three-dimensional polymers. VI. Branched polymer containing A-R-Bf-1-type units. Journal of the American Chemical Society. 1952, vol. 74, p. 2718-1723 can be obtained by polyfunctional polycondensation.

  Living cationic polymerization is used for the synthesis of polyvinyl ethers as disclosed, for example, in WO 2005/012444 (CANON), US 20050197424 (CANON) and US 20050176846 (CANON). Anionic coordination ring-opening polymerization is used, for example, for the synthesis of polyesters based on lactones. Living anionic ring-opening polymerization is used, for example, for the synthesis of polyethylene oxide macromonomers.

  Free radical polymerization (FRP) takes place via a chain mechanism, which basically consists of four different types of reactions involving free radicals: (1) radical generation (initiation) from non-radical species, (2) Radical addition (proliferation) to substituted alkenes, (3) atom transfer and atom abstraction reactions (termination by chain transfer and disproportionation), and (4) radical-radical recombination reaction (termination by bonding).

  Polymeric dispersants having some of the above polymer compositions are disclosed in US Pat. No. 6,022,908 (HP), US Pat. No. 5,302,197 (DU PONT) and US Pat. No. 6,528,557 (XEROX).

  Suitable random copolymer dispersants are disclosed in US Pat. No. 5,648,405 (DU PONT), US Pat. No. 6,245,842 (FUJI XEROX), US Pat. No. 6,262,207 (3M), US 20050004262 (KAO) and US Pat. No. 6,852,777 (KAO).

  Suitable alternating copolymer dispersants are disclosed in US 20030017271 (AKZO NOBEL).

  Suitable block copolymer dispersants, particularly block copolymer dispersants containing hydrophobic and hydrophilic blocks, are described in numerous patents. For example, US 5859113 (DU PONT) discloses an AB block copolymer and US 6413306 (DU PONT) discloses an ABC block copolymer.

  Suitable graft copolymer dispersants are disclosed in CA 2157361 (DU PONT) (hydrophobic polymer backbone and hydrophilic side chains) and other graft copolymer dispersants are disclosed in US 6652634 (LEXMARK), US 6521715 (DU PNT). Has been.

  Suitable branched copolymer dispersants are described in US 6005023 (DU PONT), US 6031019 (KAO), US 6127453 (KODAK).

  Suitable dendritic copolymer dispersants are, for example, US 6518370 (3M), US 6258896 (3M), US 2004012541 (LEXMARK), US 6649138 (QUANTUM DOT), US 200256230 (BASF), EP 1351759 A (EFKA ADDITIVES9) and EP. A (KODAK).

  A suitable design of polymeric dispersants for inkjet inks is described in SPINELLI, Harry J. et al. , Polymer Dispersants in Inkjet Technology, Advanced Materials, 1998, Vol. 10, no. 15, p. 1215-1218.

  Monomers and / or oligomers used to make polymer dispersants can be found in Polymer Handbook Vol. 1 + 2, 4th edition, edited by BRANDRUP et al. , Wiley-Interscience, 1999.

  Polymers useful as pigment dispersants include naturally occurring polymers, specific examples of which are proteins such as glue, gelatin, casein, and albumin; naturally occurring gums such as gum arabic and tragacanth; glucosides such as saponins. Alginic acid and alginic acid derivatives such as propylene glycol alginate; and cellulose derivatives such as methylcellulose, carboxymethylcellulose and ethylhydroxycellulose; wool and silk, and synthetic polymers.

  Suitable examples of monomers for synthesizing polymeric dispersants include acrylic acid, methacrylic acid, maleic acid (or their salts), maleic anhydride; alkyl (meth) acrylates (linear, branched and cycloalkyl), such as Methyl (meth) acrylate, n-butyl (meth) acrylate, tertiary butyl (meth) acrylate, cyclohexyl (meth) acrylate and 2-ethylhexyl (meth) acrylate; aryl (meth) acrylates such as benzyl (meth) acrylate and phenyl (Meth) acrylates; hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; other types of functional groups (eg oxirane, amino, fluoro, polyethylene) (Meth) acrylates having xylene, phosphate substitution) such as glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, trifluoroethyl acrylate, methoxypolyethylene glycol (meth) acrylate and tripropylene glycol (meth) acrylate phosphate; allyl Derivatives such as allyl glycidyl ether; styrenes such as styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetostyrene and styrenesulfonic acid; (meth) acrylonitrile; (meth) acrylamide (N-mono and N, N- Disubstituted), eg N-benzyl (meth) acrylamide; maleimide, eg N-phenylmaleimide; vinyl derivatives, eg vinyl alcohol, vinyl capro Including vinyl esters of, and carboxylic acids, such as vinyl acetate, vinyl butyrate and vinyl benzoate; Tam, vinylpyrrolidone, vinylimidazole, vinyl naphthalene and vinyl halides; vinyl ethers such as vinyl methyl ether. Typical condensation polymers include polyurethane, polyamide, polycarbonate, polyether, polyurea, polyimine, polyimide, polyketone, polyester, polysiloxane, phenol-formaldehyde, urea-formaldehyde, melamine-formaldehyde, polysulfide, polyacetal or combinations thereof .

  Suitable copolymer dispersants are acrylic acid / acrylonitrile copolymer, vinyl acetate / acrylic ester copolymer, acrylic acid / acrylic ester copolymer, styrene / acrylic acid copolymer, styrene / methacrylic acid copolymer, styrene / methacrylic acid / acrylic ester copolymer, styrene / Α-methylstyrene / acrylic acid copolymer, styrene / α-methylstyrene / acrylic acid / acrylic ester copolymer, styrene / maleic acid copolymer, styrene / maleic anhydride copolymer, vinylnaphthalene / acrylic acid copolymer, vinylnaphthalene / maleic acid copolymer , Vinyl acetate / ethylene copolymer, vinyl acetate / fatty acid / ethylene copolymer, vinyl acetate / maleic ester copolymer, vinyl acetate / croto Acid copolymer, vinyl acetate / acrylic acid copolymer.

Suitable chemistries for copolymer dispersants also include:
A copolymer that is the product of a condensation process of carboxylic acid-terminated polyester and poly (ethyleneimine) (made by addition polymerization); and a copolymer that is the product of the reaction of a polyfunctional isocyanate with: Compounds monosubstituted with possible groups, for example polyesters;
A compound containing two groups capable of reacting with an isocyanate (crosslinking agent); or a compound having a group capable of reacting with an isocyanate group and at least one basic ring nitrogen.

  A detailed list of suitable polymeric dispersants can be found in MC CUTCHEON, Functional Materials, North American Edition, Glen Rock, N .; J. et al. : Manufacturing Confactor Publishing Co. 1990, p. 110-129.

  Suitable pigment stabilizers are also disclosed in DE 19636382 (BAYER), US 5720802 (XEROX), US 5713993 (DU PONT), WO 96/12772 (XAAR) and US 5085689 (BASF).

  One polymer dispersant or a mixture of two or more polymer dispersants may be present to further improve dispersion stability. Sometimes surfactants can also be used as pigment dispersants, so combinations of polymer dispersants and surfactants are also possible.

  The polymeric dispersant can be nonionic, anionic or cationic in nature, and salts of ionic dispersants can also be used.

  The polymeric dispersant preferably has a degree of polymerization DP of 5 to 1000, more preferably 10 to 500, and most preferably 10 to 100.

  The polymeric dispersant preferably has a number average molecular weight Mn of 500-30000, more preferably 1500-10000.

  The polymeric dispersant preferably has an average molecular weight Mw of less than 100,000, more preferably less than 50,000, most preferably less than 30,000.

  The polymeric dispersant preferably has a polymer dispersion PD of less than 2, more preferably less than 1.75, and most preferably less than 1.5.

Commercial examples of polymer dispersants are:
• DISPERBYK® dispersant available from BYK CHEMIE GMBH;
• SOLPERSE® dispersant available from NOVEON;
-TEGO® DISPERS® dispersant available from DEGUSSA;
An EDAPLAN® dispersant available from MUENZING CHEMIE;
ETHACRYL® dispersant available from LYONDELL;
GANEX® dispersant available from ISP;
DISPEX® and EFKA® dispersants available from CIBA SPECIALTY CHEMICALS INC;
• DISPONER® dispersant available from DEUCHEM; and • JONCRYL® dispersant available from JOHNSON POLYMER.

  Particularly preferred polymer dispersants include Solsperse® dispersant from NOVEON, Efka® dispersant from CIBA SPECIALTY CHEMICALS INC, and Disperbyk® dispersant from BYK CHEMIE GMBH.

  Particularly preferred dispersants for solvent-based pigment dispersion are Solsperse® 32000 and 39000 from NOVEON.

  Particularly preferred dispersants for oil-based pigment dispersion are Solsperse® 11000, 11200, 13940, 16000, 17000 and 19000 from NOVEON.

  Particularly preferred dispersants for UV curable pigment dispersion are Solsperse® 32000 and 39000 dispersants from NOVEON.

  The polymeric dispersant is preferably used in an amount of 2 to 600% by weight, more preferably 5 to 200% by weight, based on the weight of the pigment.

Dispersion synergist The dispersion synergist usually consists of an anionic part and a cationic part. The anion portion of the dispersion synergist has molecules similar to the color pigment, and the cation portion of the dispersion synergist consists of one or more protons and / or cations to compensate for the charge of the anion portion of the dispersion synergist.

  The dispersion synergist is preferably added in a smaller amount than the polymer dispersant. The ratio of polymer dispersant / dispersion synergist depends on the pigment and should be determined experimentally. Generally, the wt% polymer dispersant / wt% dispersion synergist ratio is selected from 2: 1 to 100: 1, preferably 2: 1 to 20: 1.

  Suitable dispersion synergists that are commercially available include Solsperse® 5000 and Solsperse® 22000 from NOVEON.

  Particularly preferred pigments for magenta inks used in inkjet ink sets for making decorative laminates are diketopyrrolopyrrole pigments. In order to obtain excellent dispersion stability and quality, preferably a dispersion synergist was used for diketopyrrolopyrrole pigments as disclosed in pending European patent application EP 0511360.

  C. I. When dispersing Pigment Blue 15: 3, a sulfonated Cu-phthalocyanine dispersion synergist such as Solsperse® 5000 from NOVEON is preferred. Suitable dispersion synergists for yellow ink-jet inks include those disclosed in pending European patent application EP 05111357.

Dispersion medium In one embodiment, the dispersion medium comprises an organic solvent. Suitable organic solvents include N-containing solvents such as alcohols, ketones, esters, ethers, glycols and polyglycols and derivatives thereof, lactones, amides. Preferably, a mixture of one or more of these solvents is used.

  Examples of suitable alcohols are methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, heptyl alcohol, octyl alcohol, cyclohexyl alcohol, benzyl alcohol, phenylethyl alcohol, phenylpropyl alcohol, furfuryl alcohol, anise. Includes alcohols and fluoroalcohols.

  Examples of suitable ketones are acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl isopropyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, methyl isoamyl ketone, diethyl ketone, ethyl n-propyl ketone, ethyl isopropyl ketone. , Ethyl n-butyl ketone, ethyl isobutyl ketone, di-n-propyl ketone, diisobutyl ketone, cyclohexanone, methylcyclohexanone and isophorone, 2,4-pentanedione and hexafluoroacetone.

  Examples of suitable esters are methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, hexyl acetate, octyl acetate, benzyl acetate, phenoxyethyl acetate, ethyl phenyl acetate, methyl lactate, ethyl lactate , Propyl lactate, butyl lactate, methyl propionate, ethyl propionate, benzyl propionate, ethylene carbonate, propylene carbonate, amyl acetate, ethyl benzoate, butyl benzoate, butyl laurate, isopropyl myristate, isopropyl palmitate, triethyl Phosphate, tributyl phosphate, diethyl phthalate, dibutyl phthalate, Including ethyl malonate, dipropyl malonate, diethyl succinate, dibutyl succinate, diethyl glutarate, diethyl adipate, dibutyl adipate and diethyl sebacate.

  Examples of suitable ethers include butyl phenyl ether, benzyl ethyl ether, hexyl ether, diethyl ether, dipropyl ether, tetrahydrofuran and dioxane.

  Examples of suitable glycols and polyglycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol and tripropylene glycol.

  Examples of suitable glycols and polyglycol derivatives are alkylene glycol monoalkyl ethers, alkylene glycol dialkyl ethers, polyalkylene glycol monoalkyl ethers, ethers such as polyalkylene glycol dialkyl ethers, and the aforementioned glycol ethers such as acetate and propionate esters. In the case of dialkyl ethers, only one ether function (resulting in a mixed ether / ester) or both ether functions (resulting in a dialkyl ester) can be esterified.

  Examples of suitable alkylene glycol monoalkyl ethers are ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol mono-2-ethyl-hexyl ether, ethylene Glycol monophenyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono n-propyl ether, propylene glycol mono n-butyl ether, propylene glycol monoisobutyl ether, propylene glycol mono t-butyl ether and propylene glycol monophenyl ether Including.

  Examples of suitable alkylene glycol dialkyl ethers include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether and propylene glycol dibutyl ether.

  Examples of suitable polyalkylene glycol monoalkyl ethers are diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono n-butyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene monoethyl ether. , Triethylene glycol monobutyl ether, dipropylene monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol n-propyl ether, dipropylene glycol mono n-butyl ether, dipropylene mono t-butyl ether, tripropylene glycol monomethyl ether, tripropylene Glycol monoethyl ester Ether, tripropylene glycol monomethyl n- propyl ether and tripropylene glycol mono n- butyl ether.

  Examples of suitable polyalkylene glycol dialkyl ethers are diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, triethylene glycol methyl ethyl ether. Tetraethylene glycol methyl ethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol diisopropyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene di n-propyl ether, dipropylene di t-butyl ether, Including polypropylene glycol dimethyl ether and tripropylene glycol diethyl ether.

  Examples of suitable glycol esters are ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, Propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate and propylene glycol monomethyl ether propionate.

式中、Ｒ_１及びＲ_２は各々独立して１〜４個の炭素原子を有するアルキル基から選択され；
Ｙはエチレン基及び／又はプロピレン基を表わし；
ｎは４〜２０から選択される整数である。好ましくは、式（ＰＡＧ）によって表わされる二つ以上のポリアルキレングリコールジアルキルエーテルの混合物である。 Preferred solvents for use in pigment dispersions and inkjet inks are one or more polyalkylene glycol dialkyl ethers represented by the following formula (PAG):

Wherein R ₁ and R ₂ are each independently selected from alkyl groups having 1 to 4 carbon atoms;
Y represents an ethylene group and / or a propylene group;
n is an integer selected from 4 to 20. Preferably, it is a mixture of two or more polyalkylene glycol dialkyl ethers represented by the formula (PAG).

The alkyl groups R ₁ and R ₂ of the polyalkylene glycol dialkyl ether according to the formula (PAG) preferably represent methyl and / or ethyl. Most preferably, both alkyl groups R ₁ and R ₂ are methyl groups.

  In a preferred embodiment, the polyalkylene glycol dialkyl ether according to formula (PAG) is a polyethylene glycol dialkyl ether.

  In another preferred embodiment, a mixture of two, three, four or more polyalkylene glycol dialkyl ethers, more preferably a polyethylene glycol dialkyl ether, is present in the pigment dispersion or inkjet ink.

  Suitable mixtures of polyalkylene glycol dialkyl ethers for pigment dispersions have a molecular weight of at least 200 such as Polyglycol DME 200®, Polyglycol DME 250® and Polyglycol DME 500® from CLARIANT Contains a mixture of polyethylene glycol dimethyl ether. The polyalkylene glycol dialkyl ether used in the non-aqueous inkjet ink preferably has an average molecular weight of 200 to 800, more preferably no polyalkylene glycol dialkyl ether having a molecular weight greater than 800 is present. The mixture of polyalkylene glycol dialkyl ethers is preferably a uniform liquid mixture at room temperature.

  Suitable commercially available glycol ether solvents are Cellosolve (R) and Carbitol (R) solvents from UNION CARBIDE, Ektasolve (R) solvent from EASTMAN, Dowanol (R) solvent from DOW, SHELL CHEMICAL Oxitol (R) solvent, Dioxitol (R) solvent, Proxitol (R) solvent and Diproxitol (R) solvent, and Arcosolv (R) solvent from LYONDELL.

  Lactone is a compound having a ring structure formed by an ester bond, and is of the γ-lactone (5-membered ring structure), δ-lactone (6-membered ring structure) or ε-lactone (7-membered ring structure) type. be able to. Suitable examples of lactones are γ-butyrolactone, γ-valerolactone, γ-hexalactone, γ-heptalactone, γ-octalactone, γ-nonalactone, γ-decalactone, γ-undecalactone, δ-valerolactone, δ -Hexalactone, [delta] -heptalactone, [delta] -octalactone, [delta] -nonalactone, [delta] -decalactone, [delta] -undecalactone and [epsilon] -caprolactone.

  Suitable examples of the N-containing organic solvent include 2-pyrrolidone, N-methylpyrrolidone, N-ethyl-2-pyrrolidone, N-octyl-2-pyrrolidone, N-dodecyl-2-pyrrolidone, N, N-dimethylacetamide, N , N-dimethylformamide, acetonitrile, and N, N-dimethyldodecanamide.

  In another embodiment, the dispersion medium comprises an oil type liquid alone or in combination with an organic solvent. Suitable organic solvents include alcohols, ketones, esters, ethers, glycols and polyglycols and derivatives thereof, N-containing solvents such as lactones, amides, higher fatty acid esters and one or more of the above solvents for solvent-based dispersion media. Contains a mixture.

  The amount of polar solvent is preferably less than the amount of oil. The organic solvent preferably has a high boiling point, preferably 200 ° C. or higher. Examples of suitable combinations are described in EP 0808347 A (XAAR), especially for the use of oleyl alcohol, and in EP 1157070 A (MARCONI DATA SYSTEMS) for the combination of oil and volatile organic solvent.

  Suitable oils are saturated and unsaturated hydrocarbons, aromatic oils, paraffin oil, extracted paraffin oil, naphthenic oil, extracted naphthenic oil, hydrotreated light or heavy oil, vegetable oil, white oil, petroleum naphtha oil, hydrogen substitution Including hydrocarbons, silicones and their derivatives and mixtures.

  The hydrocarbon may be selected from straight or branched chain aliphatic hydrocarbons, alicyclic hydrocarbons and aromatic hydrocarbons. Examples of hydrocarbons are saturated hydrocarbons such as n-hexane, isohexane, n-nonane, isononane, dodecane and isododecane; unsaturated hydrocarbons such as 1-hexene, 1-heptene and 1-octene; cyclohexane, cycloheptane, cyclo Cyclic saturated hydrocarbons such as octane, cyclodecane and decalin; cyclic unsaturated hydrocarbons such as cyclohexene, cycloheptene, cyclooctene, 1,3,5,7-cyclooctatetraene, and cyclododecene; and benzene, toluene, xylene , Aromatic hydrocarbons such as naphthalene, phenanthrene, anthracene and their derivatives. In the literature, the term paraffin oil is often used. Suitable paraffin oils are mixtures of normal paraffin types (octane and higher alkanes), isoparaffins (isooctane and higher cycloalkanes) and cycloparaffins (cyclooctane and higher cycloalkanes) and paraffin oils. Can be. The term “liquid paraffin” is often used to refer to a mixture consisting mainly of the three components normal paraffin, isoparaffin and monocyclic paraffin, as described in US Pat. No. 6,730,153 (SAKATA INX). It is obtained by highly purifying the relatively volatile lubricating oil fraction, such as through sulfuric acid washing. Suitable hydrocarbons are also described as dearomatized petroleum products.

  Suitable examples of halogenated hydrocarbons include methylene dichloride, chloroform, tetrachloromethane and methyl chloroform. Other suitable examples of halogen-substituted hydrocarbons include perfluoroalkanes, fluorinated inert liquids and fluorocarbon iodides.

  Suitable examples of silicone oils are dialkylpolysiloxanes (eg hexamethyldisiloxane, tetramethyldisiloxane, octamethyltrisiloxane, hexamethyltrisiloxane, heptamethyltrisiloxane, decamethyltetrasiloxane, trifluoropropylheptamethyltrisiloxane, Diethyltetramethyldisiloxane), cyclic dialkylpolysiloxanes (eg hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetra (trifluoropropyl) tetramethylcyclotetrasiloxane), and methylphenyl silicone oil Including.

  White oil is the term used for white mineral oil, which is a highly refined mineral oil consisting of saturated aliphatic and alicyclic nonpolar hydrocarbons. White oil is hydrophobic, colorless, tasteless and odorless and does not change color over time.

  Vegetable oils include semi-drying oils such as soybean oil, cottonseed oil, sunflower oil, rapeseed oil, mustard oil, sesame oil and corn oil; non-drying oils such as olive oil, peanut oil and coconut oil; and drying oils such as linseed oil and safflower oil, These vegetable oils can be used alone or as a mixture thereof.

  Examples of other suitable oils include petroleum, non-drying oils and semi-drying oils.

  Suitable commercially available oils include Isopar® series (isoparaffin) and Varsol / Naphtha series from EXXON CHEMICAL, hydrocarbons from CHEVRON PHILLIPS CHEMICAL, and Shellsol® series from SHELL CHEMICALS. Includes aliphatic hydrocarbon types.

  Suitable commercially available normal paraffins include the Norpar® series from EXXON MOBIL CHEMICAL.

  Suitable commercially available naphthenic hydrocarbons include the Nappar® series from EXXON MOBIL CHEMICAL.

  Suitable commercial dearomatized petroleum products include the Exxsol® series from EXXON MOBIL CHEMICAL.

  Suitable commercially available fluoro-substituted hydrocarbons include fluorocarbons from DAIKIN INDUSTRIES LTD, Chemical Division.

  Suitable commercially available silicone oils include the silicone fluid series from SHIN-ETSU CHEMICAL, Silicone Division.

  Suitable commercially available white oils include Witco® white oil from CROMPTON CORPORATION.

  If the non-aqueous pigment dispersion is a curable pigment dispersion, the dispersion medium includes one or more monomers and / or oligomers to obtain a liquid dispersion medium. Sometimes it may be advantageous to add a small amount of an organic solvent to improve the solubility of the dispersant. The organic solvent content should be less than 20% by weight based on the total weight of the inkjet ink. In other cases, it may be advantageous to add a small amount of water, for example to improve the dispersion of the inkjet ink on the hydrophilic surface, but it is preferred that the inkjet ink does not contain any water.

  Preferred organic solvents include alcohols, aromatic hydrocarbons, ketones, esters, aliphatic hydrocarbons, higher fatty acids, carbitols, cellosolves, higher fatty acid esters. Suitable alcohols include methanol, ethanol, propanol and 1-butanol, 1-pentanol, 2-butanol, t-butanol. Suitable aromatic hydrocarbons include toluene and xylene. Suitable ketones include methyl ethyl ketone, methyl isobutyl ketone, 2,4-pentanedione and hexafluoroacetone. Further, glycol, glycol ether, N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide may be used.

  In the case of a curable inkjet ink, the dispersion medium is preferably composed of monomers and / or oligomers.

Monomers and oligomers Any monomer or oligomer may be used as the curable compound for the curable inkjet ink. A combination of monomers, oligomers and / or prepolymers may be used. Monomers, oligomers and / or prepolymers may have different functionalities and mixtures containing combinations of mono-, di-, tri- and higher functional monomers, oligomers and / or prepolymers may be used. . The viscosity of the inkjet ink can be adjusted by changing the ratio between monomer and oligomer.

  Any method of conventional radical polymerization, photocuring system using photoacid or photobase generator, or photoinduced alternating copolymerization may be used. In general, radical polymerization and cationic polymerization are preferred, and photoinduced alternating copolymerization that does not require an initiator may be used. Furthermore, a hybrid system combining these systems is also effective.

  Cationic polymerization is excellent due to insufficient inhibition of polymerization by oxygen, but is expensive and slow, especially under conditions of high relative humidity. If cationic polymerization is used, it is preferred to use an epoxy compound with an oxetane compound to increase the rate of polymerization. Radical polymerization is a preferred polymerization method.

  Any polymerizable compound generally known in the industry may be used. Particularly preferred for use as radiation curable compounds in radiation curable inkjet inks are monofunctional and / or polyfunctional acrylate monomers, oligomers or prepolymers such as isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, Isoamylstil acrylate, isostearyl acrylate, 2-ethylhexyl-diglycol acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl hexahydrophthalic acid, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxy Propylene glycol acrylate Phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, vinyl ether acrylate, vinyl ether ethoxy (meth) acrylate, 2- Acryloyloxyethylsuccinic acid, 2-acryloyloxyethylphthalic acid, 2-acryloxyethyl-2-hydroxyethyl-phthalic acid, lactone-modified flexible acrylate, and t-butylcyclohexyl acrylate, triethylene glycol diacrylate, tetra Ethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene Glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, dimethylol-tricyclodecane diacrylate, Bisphenol A EO (ethylene oxide) adduct diacrylate, bisphenol A PO (propylene oxide) adduct diacrylate, hydroxypivalate neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, alkoxylated dimethylol tricyclodecane diacrylate and Polytetramethylene glycol diacrylate, trimethylolpropane triacrylate, EO modified Limethylolpropane triacrylate, tri (propylene glycol) triacrylate, caprolactone modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxytetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, Glycerin propoxytriacrylate, and caprolactam-modified dipentaerythritol hexaacrylate; or N-vinylamide, such as N-vinylcaprolactam or N-vinylformamide; or acrylamide or substituted acrylamide, such as acryloylmorpholine.

  Other suitable monofunctional acrylates are caprolactone acrylate, cyclic trimethylolpropane formal acrylate, ethoxylated nonylphenol acrylate, isodecyl acrylate, isooctyl acrylate, octyldecyl acrylate, alkoxylated phenol acrylate, tridecyl acrylate and alkoxylated cyclohexanone dimethanol Contains diacrylate.

  Other suitable bifunctional acrylates include alkoxylated cyclohexanone dimethanol diacrylate, alkoxylated hexanediol diacrylate, dioxane glycol diacrylate, dioxane glycol diacrylate, cyclohexanone dimethanol diacrylate, diethylene glycol diacrylate and neopentyl glycol diacrylate. .

  Other suitable trifunctional acrylates include propoxylated glycerin triacrylate and propoxylated trimethylolpropane triacrylate.

  Other higher functionality acrylates include ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, ethoxylated pentaerythritol tetraacrylate, methoxylated glycol acrylate and acrylate esters.

  Furthermore, methacrylates corresponding to the above acrylates may be used in these acrylates. Of the methacrylates, methoxypolyethylene glycol methacrylate, methoxytriethylene glycol methacrylate, hydroxyethyl methacrylate, phenoxyethyl methacrylate, cyclohexyl methacrylate, tetraethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate are their relatively high sensitivity and sensitivity to ink receiving surfaces. Preferred for high adhesion.

  Further, the inkjet ink may also contain a polymerizable oligomer. Examples of these polymerizable oligomers include epoxy acrylates, aliphatic urethane acrylates, aromatic urethane acrylates, polyester acrylates, and linear acrylic oligomers.

  Suitable examples of the styrene compound are styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene and p-methoxy-β-methylstyrene.

  Suitable examples of vinyl naphthalene compounds are 1-vinyl naphthalene, α-methyl-1-vinyl naphthalene, β-methyl-1-vinyl naphthalene, 4-methyl-1-vinyl naphthalene and 4-methoxy-1-vinyl naphthalene. .

  Suitable examples of the N-vinyl compound include N-vinylcarbazole, N-vinylpyrrolidone, N-vinylindole, N-vinylpyrrole, N-vinylphenothiazine, N-vinylacetanilide, N-vinylethylacetamide, N-vinylsuccinimide, N-vinylphthalimide, N-vinylcaprolactam and N-vinylimidazole.

  The cationically polymerizable compound of the inkjet ink can be one or more monomers, one or more oligomers, or a combination thereof.

  Suitable examples of cationically curable compounds are described in Advances in Polymer Science, 62, pages 1 to 47 (1984) by J. Am. V. Can be found in Crivello.

  The cationically curable compound may contain at least one olefin, thioether, acetal, thioxan, thietane, aziridine, N, O, S or P-heterocyclic, aldehyde, lactam or cyclic ester group.

  Examples of cationically polymerizable compounds include monomeric and / or oligomeric epoxides, vinyl ethers, styrene, oxetanes, oxazolines, vinyl naphthalene, N-vinyl heterocyclic compounds, and tetrahydrofurfuryl compounds.

  The cationically polymerizable monomer can be mono-, di- or polyfunctional or mixtures thereof.

  Suitable cationic curable compounds having at least one epoxy group are described in “Handbook of Epoxy Resins” by Lee and Neville, McGraw Hill Book Company, New York (1967) and “Epoxy Resin Technol.”. F. Bruins, John Wiley and Sons New York (1968).

  Examples of cationically curable compounds having at least one epoxy group are 1,4-butanediol diglycidyl ether, 3- (bis (glycidyloxymethyl) methoxy) -1,2-propanediol, limonene oxide, 2-biphenyl Glycidyl ether, 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, epichlorohydrin-bisphenol S based epoxide, epoxidized styrene and epichlorohydrin-bisphenol F and A based epoxides and Contains epoxidized novolac.

  Suitable epoxy compounds containing at least two epoxy groups in the molecule are cycloaliphatic polyepoxides, polyglycidyl esters of polybasic acids, polyglycidyl ethers of polyols, polyglycidyl ethers of polyoxyalkylene glycols, polyglycidyl esters of aromatic polyols Polyglycidyl ethers of aromatic polyols, urethane polyepoxy compounds, and polyepoxypolybutadienes.

  Examples of cycloaliphatic bisepoxides are copolymers of epoxides with hydroxyl components such as glycols, polyols or vinyl ethers, such as 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexylcarboxylate, bis (3,4-epoxycyclohexyl). Methyl) adipate, limonene bisepoxide, and diglycidyl ester of hexahydrophthalic acid.

  Examples of vinyl ethers having at least one vinyl ether group are ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, butanediol divinyl ether, hydroxyl butyl vinyl ether, cyclohexane dimethanol monovinyl ether, phenyl vinyl ether, p-methylphenyl. Vinyl ether, p-methoxyphenyl vinyl ether, α-methylphenyl vinyl ether, β-methylisobutyl vinyl ether and β-chloroisobutyl vinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, dodecyl vinyl ether, die Lenglycol monovinyl ether, cyclohexanedimethanol divinyl ether, 4- (vinyloxy) butylbenzoate, bis [4- (vinyloxy) butyl] adipate, bis [4- (vinyloxy) butyl] succinate, 4- (vinyloxymethyl) cyclohexylmethyl Benzoate, bis [4- (vinyloxy) butyl] isophthalate, bis [4- (vinyloxymethyl) cyclohexylmethyl] glutarate, tris [4- (vinyloxy) butyl] trimellitate, 4- (vinyloxy) butyl steatite, bis [ 4- (vinyloxy) butyl] hexanediylbiscarbamate, bis [4- (vinyloxy) methyl] cyclohexylmethyl terephthalate, bis [4- (vinyloxy) methyl] cyclohexyl Methyl isophthalate, bis [4- (vinyloxy) butyl] (4-methyl-1,3-phenylene) -biscarbamate, bis [4- (vinyloxy) butyl] (methylenedi-4,1-phenylene) -biscarbamate and Contains 3-amino-1-propanol vinyl ether.

  Suitable examples of oxetane compounds having at least one oxetane group are 3-ethyl-3-hydroxymethyl-1-oxetane, oligomer mixture 1,4-bis [3-ethyl-3-oxetanylmethoxy] methyl] benzene, 3- Ethyl-3-phenoxymethyl-oxetane, bis ([1-ethyl (3-oxetanyl)] methyl) ether, 3-ethyl-3-[(2-ethylhexyloxy) methyl] oxetane, 3-ethyl-[(tri- Ethoxysilylpropoxy) methyl] oxetane and 3,3-dimethyl-2 (p-methoxy-phenyl) -oxetane.

  A preferred class of monomers and oligomers that can be used in both radiation and cationic curable compositions are vinyl ether acrylates such as those described in US Pat. No. 6,310,115 (AGFA), incorporated herein by reference. A particularly preferred compound is 2- (2-vinyloxyethoxy) ethyl (meth) acrylate, and most preferably the compound is 2- (2-vinyloxyethoxy) ethyl acrylate.

Initiator The curable inkjet ink also preferably includes an initiator. Initiators typically initiate the polymerization reaction. The initiator can be a thermal initiator, but is preferably a photoinitiator. Photoinitiators require less energy to activate than monomers, oligomers and / or prepolymers to form polymers. Suitable photoinitiators for use in curable inkjet inks may be Norrish type I initiators, Norrish type II initiators or photoacid generators.

  Suitable thermal initiators for use in curable inkjet inks are tertiary amyl peroxybenzoate, 4,4-azobis (4-cyanovaleric acid), 1,1'-azobis (cyclohexanecarbonitrile), 2, 2'-azobisisobutyronitrile (AIBN), benzoyl peroxide, 2,2-bis (tertiarybutylperoxy) butane, 1,1-bis (tertiarybutylperoxy) cyclohexane, 1,1-bis (Tert-butylperoxy) cyclohexane, 2,5-bis (tertiarybutylperoxy) -2,5-dimethylhexane, 2,5-bis (tertiarybutylperoxy) -2,5-dimethyl-3- Hexyne, bis (1- (tertiary-butylperoxy) -1-methylethyl) benzene, 1,1- (Tertiary-butylperoxy) -3,3,5-trimethylcyclohexane, tertiary-butyl hydroperoxide, tertiary-butyl peracetate, tertiary-butyl peroxide, tertiary-butylperoxybenzoate, tertiary-butylperoxyisopropyl Contains carbonate, cumene hydroperoxide, cyclohexanone peroxide, dicumyl peroxide, lauroyl peroxide, 2,4-pentanedione peroxide, peracetic acid and potassium persulfate.

  Photoinitiators or photoinitiator systems absorb light and are involved in the generation of initiating species such as free radicals and cations. Free radicals and cations are high energy species that induce polymerization of monomers, oligomers and polymers, and polymerization with polyfunctional monomers and oligomers that induce crosslinking.

  Irradiation with actinic radiation may be realized in two stages by changing the wavelength or intensity. In such a case, it is preferred to use two types of photoinitiators together.

  Different types of initiators can be used, for example a combination of photoinitiator and thermal initiator.

  Preferred Norrish type I initiators are benzoin ethers, benzyl ketals, α, α-dialkoxyacetophenones, α-hydroxyalkylphenones, α-aminoalkylphenones, acylphosphine oxides, acylphosphine sulfides, α-haloketones, α-halosulfones and Selected from the group consisting of α-halophenylglyoxalate.

  Preferred Norrish type II initiators are selected from the group consisting of benzophenone, thioxanthone, 1,2-diketone and anthraquinone. Preferred coinitiators are selected from the group consisting of aliphatic amines, aromatic amines and thiols. Tertiary amines, heterocyclic thiols and 4-dialkylaminobenzoic acids are particularly preferred as coinitiators.

  Suitable photoinitiators are CRIVELLO, J. et al. V. , Et al. VOLUME III: Photoinitiators for Free Radical Cation. 2nd edition. Edited by BRADLEY, G. . London, UK: John Wiley and Sons Ltd, 1998. p. 287-294.

  Specific examples of photoinitiators include but are not limited to the following compounds or combinations thereof: benzophenone and substituted benzophenones, 1-hydroxycyclohexyl phenyl ketone, thioxanthone, such as isopropylthioxanthone, 2-hydroxy-2- Methyl-1-phenylpropan-1-one, 2-benzyl-2-dimethylamino- (4-morpholinophenyl) butan-1-one, benzyldimethyl ketal, bis (2,6-dimethylbenzoyl) -2,4 , 4-Trimethylpentylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2,2-dimethoxy -1,2-diphenylethane - one or 5,7 Jiiodo 3-butoxy-6-fluorone, diphenyliodonium fluoride and triphenylsulfonium hexa full thiophosphate.

  Suitable commercially available photoinitiators are Irgacure (R) 184, Irgacure (R) 500, Irgacure (R) 907, Irgacure (R) 369, Irgacure (R) 1700, available from CIBA SPECIALTY CHEMICALS. Irgacure (R) 651, Irgacure (R) 819, Irgacure (R) 1000, Irgacure (R) 1300, Irgacure (R) 1870, Darocur (R) 1173, Darocur (R) 2959, Darocur (R) 4265 and Darocur (R) ITX, from Lucerin TPO, LAMBERTI available from BASF AG Available Esacure (R) KT046, Esacure (R) KIP150, Esacure (R) KT37 and Esacure (R) EDB, H-Nu (R) 470 and H-Nu available from SPECTRA GROUP Ltd (Registered trademark) 470X.

  Suitable cationic photoinitiators include compounds that form sufficient aprotic or Bronsted acid to initiate polymerization upon exposure to ultraviolet and / or visible light. The photoinitiator used may be a single compound, a mixture of two or more active compounds, or a combination of two or more different compounds, ie a coinitiator. Non-limiting examples of suitable cationic photoinitiators are aryldiazonium salts, diaryliodonium salts, triarylsulfonium salts, triarylselenonium salts and the like.

  The curable inkjet ink may contain a photoinitiator system containing one or more photoinitiators and one or more sensitizers that transfer energy to the photoinitiator. Suitable sensitizers are photoreducible xanthene, fluorene, benzoxanthene, benzothioxanthene, thiazine, oxazine, coumarin, pyronin, porphyrin, acridine, azo, diazo, cyanine, merocyanine, diarylmethyl, triarylmethyl, anthraquinone, phenylene Including diamine, benzimidazole, fluorochrome, quinoline, tetrazole, naphthol, benzidine, rhodamine, indigo and / or indanthrene dyes. The amount of sensitizer is generally from 0.01 to 15% by weight, preferably from 0.05 to 5% by weight, in each case based on the total weight of the curable inkjet ink.

  In order to further increase the photosensitivity, the curable inkjet ink may further contain a coinitiator. For example, combinations of titanocene and trichloromethyl-s-triazine, titanocene and ketoxime ether, acridine and trichloromethyl-s-triazine are known. Further increases in sensitivity can be achieved by adding dibenzalacetone or amino acid derivatives. The amount of coinitiator is generally from 0.01 to 20% by weight, preferably from 0.05 to 10% by weight, in each case based on the total weight of the curable inkjet ink.

Suitable examples of coinitiators can be divided into four groups:
(1) Tertiary aliphatic amines such as methyldiethanolamine, dimethylethanolamine, triethanolamine, triethylamine and N-methylmorpholine;
(2) aromatic amines such as amylparadimethylaminobenzoate, 2-n-butoxyethyl-4- (dimethylamino) benzoate, 2- (dimethylamino) ethylbenzoate, ethyl-4- (dimethylamino) benzoate, and 2 -Ethylhexyl-4- (dimethylamino) benzoate;
(3) (meth) acrylated amines such as dialkylaminoalkyl (meth) acrylates (eg diethylaminoethyl acrylate) or N-morpholinoalkyl- (meth) acrylates (eg N-morpholinoethyl acrylate); and (4) amides Or urea.
A preferred coinitiator is aminobenzoate.

A preferred initiator system is 2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetraphenyl-, corresponding to the following chemical formula in the presence of a co-initiator such as 2-mercaptobenzoxazole: (7Cl, 8Cl) 4,4'-bi-4H-imidazole:

Another preferred type of initiator is an oxime ester. Suitable examples have the following chemical formula:

  The preferred amount of initiator is 0.3-50% by weight of the total weight of the curable liquid, more preferably 1-15% by weight of the total weight of the curable inkjet ink.

  Irradiation with actinic radiation may be realized in two stages by changing the wavelength or intensity. In such a case, it is preferable to use two types of photoinitiators together.

Inhibitors Suitable polymerization inhibitors include phenothiazine, phenolic antioxidants, hindered amine light stabilizers, phosphorescent antioxidants, hydroquinone monomethyl ether commonly used for (meth) acrylate monomers, hydroquinone, t-butylcatechol, Pyrogallol may be used. Of these, phenol compounds having a double bond in the molecule derived from acrylic acid are particularly preferred because they have a polymerization inhibiting effect even when heated in a closed oxygen-free environment. Suitable inhibitors are for example Sumitomo Chemical Co. Sumilizer (R) GA-80, Sumilizer (R) GM and Sumilizer (R) GS manufactured by Ltd, Ciba Irgastab (R) UV10 from CIBA Specialty Products and Genord (R) available from RAHN ) 16.

  Since excessive addition of these polymerization inhibitors reduces ink sensitivity to curing, it is preferred to determine the amount that can prevent polymerization prior to blending. The amount of polymerization inhibitor is generally 200-20000 ppm of the total weight of the curable inkjet ink.

Surfactants Surfactants can be anionic, cationic, nonionic, or zwitterionic, usually in a total amount of less than 20% by weight based on the total weight of the inkjet ink, especially in the total weight of the inkjet ink. Based on a total amount of less than 10% by weight.

  Suitable surfactants include fluorinated surfactants, fatty acid salts, ester salts of higher alcohols, alkylbenzene sulfonate salts, sulfone succinate ester salts and phosphate esters of higher alcohols (eg, sodium dodecyl benzene sulfonate and sodium dioctyl sulfos). Succinates), ethylene oxide adducts of higher alcohols, ethylene oxide adducts of alkylphenols, ethylene oxide adducts of polyhydric alcohol fatty acid esters, and acetylene glycol and its ethylene oxide adducts (eg, polyoxyethylene nonyl phenyl ether, and AIR PRODUCTS & CHEMICALS INC) Available SURFYNOL® 104, 104H, 440, 465 and TG) Including.

  Preferred surfactants for non-aqueous inkjet inks are selected from fluorosurfactants (eg fluorinated hydrocarbons) and silicone surfactants. The silicone is typically a siloxane and can be alkoxylated, polyester modified, polyether modified hydroxy functional, amine modified, epoxy modified and other modified or combinations thereof. A preferred siloxane is a polymer, such as polydimethylsiloxane.

  In curable inkjet inks, fluorinated or silicone compounds may be used as surfactants, preferably crosslinkable surfactants are used. Polymerizable monomers having a surfactant effect include silicone modified acrylates, silicone modified methacrylates, acrylated siloxanes, polyether modified acrylic modified siloxanes, fluorinated acrylates, and fluorinated methacrylates. The polymerizable monomer having a surfactant effect can be a mono, di, tri or higher functionality (meth) acrylate or a mixture thereof.

Binder The two or more color inkjet inks of the inkjet ink set according to the present invention may comprise a binder resin. The binder functions as a viscosity control agent and provides fixability to a support, such as a polyvinyl chloride support. The binder preferably has good solubility in the solvent.

  The non-aqueous inkjet ink composition preferably contains a binder resin. The binder functions as a viscosity control agent and provides fixability to a polymer resin support, such as a polyvinyl chloride support (also referred to as a vinyl support). The binder must be selected to have good solubility in the solvent.

  Suitable examples of the binder resin include acrylic resin, modified acrylic resin, styrene acrylic resin, acrylic copolymer, acrylate resin, aldehyde resin, rosin, rosin ester, modified rosin and modified rosin resin, acetyl polymer, acetal resin such as polyvinyl butyral, Ketone resin, phenolic resin and modified phenolic resin, maleic resin and modified maleic resin, terpene resin, polyester resin, polyamide resin, polyurethane resin, epoxy resin, vinyl resin, vinyl chloride-vinyl acetate copolymer resin, nitrocellulose, cellulose acetopropio Cellulose-type resins such as nate and cellulose acetate butyrate, and vinyltoluene-α-methylstyrene copolymer resins. These binders may be used alone or in a mixture thereof. The binder is preferably a film-forming thermoplastic resin.

  The amount of binder resin in the inkjet ink is preferably in the range of 0.1 to 30 wt%, more preferably 1 to 20 wt%, most preferably 2 to 10 wt% based on the total weight of the inkjet ink.

Humectant / Penetration Agent If two or more color inkjet inks of the same color and color density contain an organic solvent or water, at least one humectant is added to reduce nozzle clogging by its ability to reduce the evaporation rate of the ink. In order to prevent this, it is preferable to be present in the ink.

  Suitable humectants are triacetin, N-methyl-2-pyrrolidone, glycerol, urea, thiourea, ethylene urea, alkyl urea, alkyl thiourea, dialkyl urea and dialkyl thiourea, diols (ethanediol, propanediol, propanetriol, butanediol, Including pentanediol and hexanediol); glycols (including propylene glycol, polypropylene glycol, ethylene glycol, polyethylene glycol, diethylene glycol, tetraethylene glycol), and mixtures and derivatives thereof. Preferred humectants are triethylene glycol monobutyl ether, glycerol and 1,2-hexanediol. The humectant is added to the ink jet ink formulation in an amount of 0.1-40% by weight of the formulation, more preferably 0.1-10% by weight of the formulation, most preferably about 4.0-6.0% by weight It is preferred that

Other Additives Two or more color inkjet inks of the inkjet ink set according to the present invention may contain other additives such as buffers, fungicides, pH adjusters, conductivity adjusters, chelating agents, rust inhibitors, Light stabilizers, dendrimers, polymers, crosslinking agents, conductive aids, sequestering agents and soluble electrolytes as chelating agents, compounds that introduce additional security functions, and the like may also be included. Such additives may be included in any effective amount, if desired, in two or more color inkjet inks of the inkjet ink set according to the present invention.

  Compounds for introducing additional security features include fluorescent compounds, phosphorescent compounds, thermochromic compounds, iridescent compounds and magnetic particles. Suitable UV fluorescent and phosphorescent compounds include LUMILUX® luminescent pigments from HONEYWELL, UVITEX® OB from CIBA-GEIGY, KEYFLUOR® dyes and pigments from KEYSTONE, and fluorescent dyes from SYNTHEGEN. Including.

  The two or more color ink-jet inks of the ink-jet ink set according to the present invention may further comprise conducting or semiconducting polymers such as polyaniline, polypyrrole, polythiophene such as poly (ethylenedioxythiophene) (PEDOT), substituted or unsubstituted poly ( (Phenylene vinylene) (PPV), such as PPV and MEH-PPV, polyfluorene, such as PF6, may be included.

Manufacture of colored inkjet inks Colored inkjet inks may be manufactured by precipitating or pulverizing pigments in a dispersion medium in the presence of a polymeric dispersant.

  Mixing devices may include press kneaders, open kneaders, planetary mixers, dissolvers, and Dalton universal mixers. Suitable milling and dispersing equipment may include ball mills, pearl mills, colloid mills, high speed dispersers, double rollers, bead mills, paint conditioners, and triple rollers. The dispersion may also be made using ultrasonic energy.

  Many different types of materials, such as glass, ceramics, metals, and plastics may be used as the grinding media. In a preferred embodiment, the grinding media can comprise particles, preferably of substantially spherical shape, such as beads consisting essentially of a polymer resin or yttrium stabilized zirconium oxide beads.

  In the mixing, pulverizing and dispersing steps, each step is performed with cooling to prevent heat build-up, and as much as possible under light conditions where actinic radiation is substantially excluded for radiation curable inkjet inks. Done.

  Ink jet inks may contain more than one pigment, the ink jet ink may be made using a separate dispersion for each pigment, or some pigments may be mixed during the preparation of the dispersion. Or it may be co-ground.

  The dispersion process can be carried out continuously, batchwise or semi-batchwise.

  The preferred amounts and ratios of the components of the mill mill will vary widely depending on the particular material and intended use. The contents of the pulverized mixture include mill pulverized material and pulverized media. The mill grind includes a pigment, a polymer dispersant and a liquid carrier. For inkjet inks, the pigment is usually present in the mill pulverized product at 1 to 50% by weight excluding the pulverized media. The weight ratio of pigment to polymer dispersant is 20: 1 to 1: 2.

  The milling time can vary widely and depends on the pigment, mechanical means and chosen residence conditions, initial and desired final particle size, and the like. In the present invention, a pigment dispersion having an average particle size of less than 100 nm may be prepared.

  After milling is complete, the milling media is separated from the milled particulate compound (either in dry or liquid dispersion form) using conventional separation techniques such as filtration, sieving through a mesh screen. . Often sieving is incorporated into a mill, such as a bead mill. The finely divided pigment concentrate is preferably separated from the finely divided medium by filtration.

  In general, it is desirable to make an inkjet ink in the form of a concentrated mill grind, which is then diluted to a suitable concentration for use in an inkjet printing system. This technology allows the production of large amounts of pigment ink from the equipment. By dilution, the inkjet ink is adjusted to the desired viscosity, surface tension, color, hue, saturation density, and print area coverage for the particular application.

Spectral Separation Ratio Spectral separation ratio SSF has been found to be an excellent measure for characterizing pigmented inkjet inks. This is because it takes into account properties relating to light absorption (eg wavelength of maximum absorbance λ _max , shape of absorption spectrum and absorbance value at λ _max ) and properties related to dispersion quality and stability.

  Measuring absorbance at higher wavelengths gives an indication of the shape of the absorption spectrum. The dispersion quality can be evaluated based on the phenomenon of light scattering induced by solid particles in solution. When measured by transmission, light scattering in the pigment ink may be detected as an increased absorbance at a wavelength higher than the absorbance peak of the actual pigment. Dispersion stability can be evaluated, for example, by comparing SSF before and after heat treatment at 80 ° C. for one week.

The spectral separation SSF of the ink is calculated by comparing the maximum absorbance with the absorbance at a higher reference wavelength λ _ref using the image of the image ejected on the support or the recorded spectral data of the ink solution. Spectral separation is calculated as the ratio of maximum absorbance A _max to absorbance A _{ref at} the reference wavelength.

  SSF is an excellent tool for designing inkjet sets with a large color gamut. Often inkjet ink sets are currently commercialized, where different inks do not fit well together. For example, the combined absorption of all inks does not give complete absorption over the entire visible spectrum. For example, there are “gaps” between the absorption spectra of the colorants. Another problem is that one ink can absorb in the range of another ink. The resulting color gamut of these inkjet ink sets is low or level.

Materials All materials used in the following examples are from Aldrich Chemical Co. unless otherwise specified. (Belgium) and Acros (Belgium) were readily available from standard sources. The water used was deionized water.
Cinquasia® Magenta RT-355-D is a quinacridone pigment from CIBA SPECIALTY CHEMICALS.
Sunfast® Blue 15: 3 is a cyan pigment (CI Pigment Blue 15: 3) available from SUN CHEMICAL.
SOLPERSE® 35000 and SOLPERSE® 39000 are polyethyleneimine polyester superdispersants from NOVEON.
Solsperse® 5000 is a dispersion synergist from NOVEON.
Genorad® 16 is a polymerization inhibitor from RAHN AG.
DPGDA is dipropylene glycol diacrylate from SARTOMER.
Sartomer® SR9003 is a bifunctional acrylate monomer available from SARTOMER.
Craynor® CN386 is an amine-modified acrylate synergist available from SARTOMER.
Genocure® EPD is ethyl-4-dimethylaminobenzoate from RAHN AG.
Genocure® TPO is 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide from RAHN AG.
Genocure® PBZ is a photoinitiator 4-phenylbenzophenone from RAHN AG.
Genocure® ITX is a photoinitiator isothioxanthone from RAHN AG.
BYK® UV3510 is a polyether modified polydimethylsiloxane wetting agent from BYK CHEMIE GMBH.
Byk®-333 is a surfactant from BYK CHEMIE GMBH.
Fasson PE85 white / S692N / BG40 is a brown coextruded and corona treated white polyethylene support from AVERY DENNISON.
PE paper is a polyethylene coated primed RC paper available from MONDI PACKAGING.
Rayoart CGS92 is a clear, biaxially oriented polypropylene film with a high gloss side coating from INNOVIA FILMS.
SeeMee Standard Easy is Seemee backlit standard easy, VERSEIDAG-INDUTEX GMBH, double-sided coated PVC.
Fasson MC Primecoat S2000N is a FASSON MC Primecoat / S2000N / HF80 from AVERY DENNISON, white, one side machine coated, wood-free printing paper support.
Oracle 1640 is an Oracle Blank 1640 Print Vinyl from ANTALIS, an adhesive polyvinyl chloride support.
Biprint 650 gr is a biprint blank / couleur from ANTALIS, a corona-treated polypropylene cardboard.

Measuring method Measurement of SSF The spectral separation SSF of the ink was calculated by using the recorded spectral data of the ink solution and comparing the maximum absorbance with the absorbance at the reference wavelength. The choice of this reference wavelength depends on the pigment used:
If the color ink has a maximum absorbance A _max of 400-500 nm, then the absorbance A _ref must be determined at a reference wavelength of 600 nm.
If the color ink has a maximum absorbance A _max of 500-600 nm, then the absorbance A _ref must be determined at a reference wavelength of 650 nm.
If the color ink has a maximum absorbance A _max of 600-700 nm, then the absorbance A _ref must be determined at a reference wavelength of 830 nm.

Absorbance was measured by transmission using a Shimadzu UV-2101 PC double beam-spectrophotometer. The inkjet ink was diluted with ethyl acetate to have a pigment concentration according to Table 4.

The spectrophotometric measurement of the UV-VIS-NIR absorption spectrum of the diluted ink was performed in transmission mode using a double beam spectrophotometer using the settings in Table 5 . A quartz cell with a 10 mm path length was used and ethyl acetate was selected as the blank.

  An effective colored inkjet ink that exhibits a narrow absorption spectrum and a high maximum absorbance has a value of at least 30 SSF.

2. Average Particle Size The average particle size of pigment particles in non-aqueous inkjet inks was measured with a Brookhaven Instruments Particle Sizer BI 90plus based on the principle of dynamic light scattering. The ink or dispersion was diluted with ethyl acetate to a pigment concentration of 0.002 wt%. The measurement settings for BI90plus were 5 times at 23 ° C., 90 ° angle, 635 nm wavelength and graphics = correction function.

  For good ink jet properties (jetting properties and print quality), the average particle size of the dispersed particles should be less than 200 nm, preferably 150 nm.

3. Dispersion stability Dispersion stability was evaluated by comparing the particle size before and after heat treatment at 83 ° C for 7 days. Colored inkjet inks exhibiting good dispersion stability have a particle size of 200 nm or less, preferably 150 nm or less after heat treatment.

4). Surface tension The surface tension of the inkjet ink was measured after 60 seconds at 25 ° C. with a KRUESS tensiometer K9.

5). Viscosity The viscosity of the ink-jet ink was measured using a Brookfield DV-II + viscometer at a shear rate of 4 RPM using a CPE 40 spindle and 25 ° C.

6). Dot Size Dot size was measured with CellCheck CNC-SLS (from M-Service & Gelate-Peter Mueller, Germany) using a 150 × microscope objective connected to a WAT-202B camera (from Watec Co., Ltd., Japan). Measured. The average of the five dot size measurements was calculated using the software Metric version 8.02 Live (from M-Service & Geraete-Peter Mueller, Germany).

7). Curing speed The percentage of the lamp's maximum output is taken as a measure of curing speed, the lower the number, the higher the curing speed. The sample was considered fully cured when it did not cause visual damage by scratching with a Q tip.

8). The surface energy of the support The Owens-Wendt equation was used to calculate the surface energy σ _S of the support in the same way as disclosed in US 200509245 (AGFA).

9. CIE ΔE2000
The method used is disclosed in the above paragraph "Same color and color density".

Example 1
This example shows how the same dot size can be obtained on different supports using two curable inkjet inks with different surface tensions.

Preparation of inkjet ink A dense pigment dispersion P1 was prepared according to Table 6 .

  The concentrated pigment dispersion P1 comprises 360.0 g of the pigment Cinquasia® Magenta RT-355-D, 36.0 g of a 50% solution of the inhibitor Genorad® 16 in DPGDA, and a polymer dispersant in DPGDA 1028.6 g of a 35% solution of Solsperse® 35000 was added to DISPERLUX S. A. R. L. , Luxembourg using a DISPERLUX® Laboratory Dissolver YELLOW 075 for 30 minutes. The finely ground mixture was then transferred to NETZSCH (0.45% volume loading with 0.4 mm diameter yttrium stabilized zirconium oxide beads (“High Abrasion Resistant Zirconia Grinding Media” from TOSOH Co.) and a residence time of 85 minutes. Milled under cooling with LABSTAR 1 at a rotational speed of 13 m / s and a flow rate of 0.6 L / min After milling, the dispersion was separated from the beads using a filter cloth. Had an average particle size of 96 nm and an SSF of 60.

The two curable magenta inkjet inks INK-1 and INK-2 were prepared in the same way from the thick pigment dispersion P1 by adding the remaining components under stirring at 20 ° C. to obtain a composition as shown in Table 7. Manufactured by.

  The curable inkjet inks INK-1 and INK-2 had surface tensions of 35.1 mN / m and 21.8 mN / m at 20 ° C., respectively.

Printing and evaluation
Table 8 shows five different supports and their surface energy, which were selected for this example.

  Five supports SUB-1 to SUB-5 are curable inkjet inks INK-1 and INK-2, and curable inkjet inks INK-1 and INK- selected to have a print dot size of 110 μm. Printed with an ink mixture from 2.

  The ink was printed on a custom printer equipped with a fixed UPH® print head from AGFA at a distance between the 1.0 mm nozzle plate and the ink receiver. The ink was fired in-line using a 120W DPL-lamp that was jetted at 5dpd with a resolution of 360x360dpi and gave 50W exposure at 400mm / s. Final cure was given by passing the image fired at 330 mm / s twice with a 50 W exposure. The time from spraying to curing was 1.3 seconds. The distance between the UV lamp and the ink receiver was 2.2 mm. The injection temperature was 45 ° C.

The dot sizes obtained for the curable inkjet inks INK-1, INK-2 and the ink mixture are shown in Table 9 .

From Table 9 , a very consistent image quality is obtained using an ink mixture that delivers a dot size of about 110 μm compared to a print obtained with one of the curable inkjet inks INK-1 or INK-2. It is clear that In general, it was noticed that the dot size from inks without any surfactant first decreased slightly with the addition of surfactant and then increased again with the addition of additional surfactant.

Inkjet ink INK-2 should be selected as a function of the desired dot size and the selected substrate to be printed. For example, if we wanted to have a dot size of 120 μm, this was not possible with INK-2 on the support SUB-3 unless combined with another surface treatment. However, a dot size of 120 μm could be obtained for the other supports SUB-4 and SUB-5, which already required a high amount of INK-3. This is because it was within the range of INK-1 and INK-2. SUB-4 and SUB-5 were printed with the ink mixture according to Table 10 .

Another observation is that there is no correlation between the surface tension of the ink mixture and the surface energy of the support to obtain the same dot size. This is shown in Table 11 .

  Frequently commercially available substrates are modified in some way, which affects the physical properties of the ink, such as dispersion and adhesion. Supports SUB-1 and SUB-2 are both polyethylene supports, but SUB-2 contains titanium dioxide as a whitening agent. The support SUB-4 had a polymethyl methacrylate coating. Therefore, instead of measuring the surface energy of the support and trying to correlate it with the surface tension of the ink mixture, it is better to perform a dot size print test on the support in a range of different ink mixtures. is there.

Example 2
This example shows a dot size printing test on two other supports SUB-6 and SUB-7 using the same curable inkjet inks INK-1 and INK-2 ink mixture of Example 1.

Printing and Evaluation SUB-6 was a PVC support, against which Oracle 1640 was used, while SUB-7 was a polypropylene support, against which Biprint 650gr was used. The resulting dot sizes for ink mixtures of curable inkjet inks INK-1 and INK-2 printed in the same manner as Example 1 on supports SUB-6 and SUB-7 are shown in Table 12 . The column “wt% surfactant” corresponds to the amount of surfactant Byk UV 3510 present in the ink mixture.

From Table 12 , for a dot size of 110 μm on the support SUB-6, the surfactant concentration of the ink mixture should be 0.050 to 0.100 wt% based on the total weight of the ink mixture. Recognize. For SUB-7, the surfactant concentration of the ink mixture should be 1.000 to 2.000 wt% based on the total weight of the ink mixture. To determine the correct ink mixture, the second dot size print test can be done in a narrow range, or it plots the dot size as a function of the amount of INK-2 or surfactant concentration in the ink mixture. Can be derived from the graph. For example, the graph for SUB-7 is quite linear with 1.000 to 2.000 wt% surfactant and the surfactant concentration should be about 1.31 wt%, i.e. the total weight of the ink mixture. It can be derived that an ink mixture containing 56.33 wt% INK-1 and 43.67 wt% INK-2 should be used.

The dot size data in Table 12 reveals that the two supports react differently to the ink mixture. This dot size data obtained for a particular ink mixture can be stored in a data library for future use of the same support. This improves productivity in an industrial printing environment. This is because the time that must be spent adjusting the ink and support for the desired dispersion of the ink on the support that greatly determines the image quality is eliminated.

Example 3
This example shows how high cure speeds can be obtained for an ink mixture of two curable inkjet inks. These inks will have unacceptable dispersion stability if made alone.

Manufacture of Inkjet Ink A dense pigment dispersion P2 was manufactured according to Table 13 .

  Concentrated pigment dispersion P2 consists of 14.00 g of a 50% solution of the inhibitor Genorad® 16 in DPGDA, 5.25 g of Solsperse® 5000, the polymer dispersant Solsperse® 39000 in DPGDA. 326.67 g of 30% solution and 256.08 g of DPGDA were added to DISPERLUX S. A. R. L. , Luxembourg using a DISPERLUX® Laboratory Dissolver YELLOW075. The milled mixture was then passed through an Eiger bead mill with 52% volume filling with 0.4 mm diameter yttrium stabilized zirconium oxide beads (“High Abrasion Resistant Zirconia Grinding Media” from TOSOH Co.) and a residence time of 25 minutes. Milled under cooling at a rotational speed of 4250 RPM. After milling, the dispersion was separated from the beads using a filter cloth. The dense pigment dispersion P2 has an average particle size of 103 nm, 53 mPa.s. had a viscosity of s and an SSF of 37.

Four curable cyan inkjet inks INK-3 to INK-6 were produced in the same way from the concentrated pigment dispersion P2 to obtain compositions as shown in Table 14 .

  The curable cyan inkjet INK-5 and INK-6, respectively, lacked the coinitiator Craynor® CN386 and the photoinitiator Genocure® ITX. Ink mixture MIX-56 was made by mixing curable cyan inkjet inks INK-5 and INK-6 in a 50:50 wt% ratio.

Ink-jet ink evaluation The dispersion stability of the curable cyan ink-jet inks INK-3 to INK-6 and the ink mixture MIX-56 compares the average particle size again after the production of the ink and after the heat treatment at 83 ° C. for 7 days. Determined by that. The average particle size of the heat-treated ink mixture MIX-56 was obtained by mixing the ink-jet inks INK-5 and INK-6 in a 50:50 wt% ratio after being subjected to heat treatment at 83 ° C. for 7 days. . For good dispersion stability, the average particle size in the ink should be kept below 150 nm.

While cure speed can be increased by adding a number of coinitiators Craynor® CN386, increasing the amount of coinitiator also degrades dispersion stability. Table 15 shows that the ink mixture MIX-56 exhibits better dispersion stability than the inkjet inks INK-3 and INK-4, and at the same time can be cured at very high cure speeds.

Example 4
This example shows when two inkjet inks are considered to have the same color and color density.

  As already mentioned, the two inks are considered to have different colors and densities if CIE ΔE2000 is greater than 5.0. For most inkjet applications, such as wide format inkjet printing applications, if the CIE ΔE2000 value is less than or equal to 2.0, then the difference in color and density of the two inks is acceptable. Can do. The more important the inkjet application, which is usually determined by the visual distance of the image, the smaller the CIE ΔE2000 value should be.

CIE ΔE2000 was determined for the INK-3 to INK-6 inks in Table 14 , while the INK-3 ink was used as the first ink, ie, as a reference. The inks differ somewhat in composition, but all contain the same amount of cyan pigment. Values obtained for CIE Derutai2000 of Table 16, what gives one impression weighing errors can be expected as "normal" ink manufacturing variation and the like purity or raw materials.

In another experiment, cyan ink INK-3 was diluted with DPGDA and the CIE ΔE2000 between INK-3 and diluted ink was determined. The results are given by Table 17.

By comparing Table 16 and Table 17 , it can be concluded that the “normal ink production change” in Table 16 is well within a 5% margin. For inkjet applications requiring CIE ΔE2000 less than 2.0, a 10% or even 15% dilution can be tolerated for cyan ink. However, image differences due to changes in colorant concentration can be more easily noticed for black and magenta inks. For the latter two, 10% dilution can be considered the upper limit. For high quality ink jet printing applications, the mixing error of two or more inks should be lower than 5%. That is, it should be a value for CIE ΔE2000 less than 1.0.

Claims (20)

Inkjet printing method including the following steps in order:
a) preparing two or more color inkjet inks having the same color and color density but different composition for an inkjet printer;
b) mixing the two or more color inkjet inks in controlled amounts; and c) printing the mixture of the two or more color inkjet inks on an ink receiver with an inkjet printer.   The inkjet printing method of claim 1, wherein two or more color inkjet inks having the same color and color density have a pair of color differences CIE ΔE2000 equal to or less than 2.0.   The inkjet printing method according to claim 1 or 2, wherein two or more color inkjet inks contain the same colorant.   The inkjet printing method according to any one of claims 1 to 3, wherein the surface tension of the color inkjet ink differs by more than 3.0 mN / m.   Inkjet printing according to any of claims 1 to 4, wherein the controlled amount for mixing two or more color inkjet inks is selected from a print test comprising a number of ink mixtures printed on the ink receiver. Law.   6. The ink jet printing method according to claim 5, wherein the result of the print test is stored in a data library.   7. An ink jet printing method according to claim 6, wherein the data library includes information about physical properties and / or image quality of the ink mixture for a plurality of ink receivers.   8. The ink jet printing method according to claim 7, wherein the data library is stored and managed by a computer.   A controlled amount for mixing two or more color inkjet inks is selected from a data library containing information about the physical properties and / or image quality of the mixture of two or more color inkjet inks on the ink receiver. The ink-jet printing method according to claim 1.   An inkjet ink set comprising two or more color inkjet inks having the same color and color density but different composition, wherein the two or more color inkjet inks contain the same colorant set.   11. The inkjet ink set of claim 10, wherein two or more color inkjet inks having the same color and color density have a pair of color differences CIE ΔE2000 equal to or less than 2.0.   The inkjet ink set according to any of claims 10 to 11, wherein the surface tension of the first ink differs from that of the second ink of two or more color inkjet inks having the same color and color density by more than 3.0 mN / m. .   The viscosity of the first ink is the same as that of the second ink of two or more color inkjet inks having the same color and color density at 5.0 ° C. at 30 ° C. The inkjet ink set according to any one of claims 10 to 12, which is more than s.   The inkjet ink set according to any one of claims 10 to 13, wherein the amount and / or type of solvent in the first ink is different from that in the second ink of two or more color inkjet inks having the same color and color density. .   The inkjet ink set according to any one of claims 10 to 14, wherein the amount and / or type of monomer in the first ink is different from that in the second ink of two or more color inkjet inks having the same color and color density. .   Inkjet ink according to any of claims 10 to 15, wherein the amount and / or type of initiator in the first ink is different from that in the second ink of two or more color inkjet inks having the same color and color density. set.   The inkjet ink set according to any one of claims 10 to 16, wherein the volume of the first ink is different from that of the second ink of two or more color inkjet inks having the same color and color density.   An inkjet printer comprising the inkjet ink set defined by any one of claims 10 to 17.   A combination of an ink jet printer according to claim 18 and means for evaluating or measuring properties relating to print quality.   20. A combination according to claim 19, wherein the ink jet printer includes means for evaluating or measuring properties related to print quality.

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