Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/0011—Pre-treatment or treatment during printing of the recording material, e.g. heating, irradiating
  • B41M5/0017—Application of ink-fixing material, e.g. mordant, precipitating agent, on the substrate prior to printing, e.g. by ink-jet printing, coating or spraying
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
  • B41M5/5218—Macromolecular coatings characterised by inorganic additives, e.g. pigments, clays
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
  • B41M5/5245—Macromolecular coatings characterised by the use of polymers containing cationic or anionic groups, e.g. mordants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
  • B41M5/5254—Macromolecular coatings characterised by the use of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. vinyl polymers

Definitions

• This invention relates to the field of inkj et printing. More particularly, it relates to an aqueous composition that can be applied to a substrate as a pre-treatment to form an inkjet receiving medium having an opaque (“white”) coating or pattern.
• This inkjet receiving medium has enhanced inkjet printing and imaging properties, and can be printed using aqueous pigment-based inkjet inks or aqueous colorless inkjet inks.
• aqueous inks particularly those having anionically-stabilized dispersed pigment colorants onto a substrate having cations of a multivalent metal salt on the surface thereof.
• the presence of such multivalent metal cations can be used to prevent deposited ink drops from penetrating too far below the surface of a water-absorptive substrate, thereby preventing a lowering of optical density.
• the multivalent metal cations can also be used to prevent bleeding or coalescing of adjacent deposited ink drops of the same or different colors on a less absorbent substrate such as a hydrophobic substrate, thereby preventing the formation of blurry or grainy appearing images.
• Surface treatments comprising aqueous salts of multivalent metal ions are particularly advantageous for high speed printing with page-wide inkjet arrays whereby adjacent drops of ink are deposited within just a few microseconds of each other onto the substrate.
• U.S. Patents 9,067,448 (Dannhauser et al.) and 9,434,201 (Dannhauser et al.) describe inkjet receiving media suitable for high speed inkjet printing, which media include a substrate having a topmost layer coated thereon comprising an aqueous soluble salt of a multivalent metal cation and a crosslinked hydrophilic polymer binder. Various inorganic particles of various types may also be present in this topmost layer.
• U.S. Patent 8,562,126 (Xiang et al.) describes inkjet receiving media comprising a substrate and a topmost layer coated thereon, wherein the topmost layer includes one or more aqueous soluble salts of multivalent metal cations, a cationic polyelectrolyte comprising amidine moieties, and a second polymer which is distinct from the cationic poly electrolyte comprising amidine moieties.
• the inkjet receiving media known in the art for high-speed inkjet printing using anionically-stabilized aqueous pigment-based inks are sometimes low in opacity or even transparent, and in many instances, the inkjet-receptive layers on these media such as those described in the patents described above, are also visually clear and transparent or translucent.
• This objective may be possible by inkjet-printing a layer of white ink, such as one described in U.S. Patent 9,994,723 (Bauer et al.), before applying a known ink-receptive layer formulation. While this approach can provide some opacity in the inkjet receptive media, it adds the complexity of needing a separate “white” ink layer under the ink-receptive layer which entails a separate ink deposition or coating step. Multiple layer formation on a substrate then requires a careful optimization of the multi-step operations for applying multiple layers to ensure good adhesive and to avoid adverse interactions between the layer formulations. Moreover, the application of a white inkjet ink may not provide the desired opacity to the resulting inkjet receptive media.
• the present invention provides an aqueous composition for pre-treating a substrate prior to inkjet printing thereon, the aqueous composition having at least 2% solids and up to and including 90% solids, and the aqueous composition comprises:
• Some particularly useful embodiments of this invention include an aqueous composition for pre-treating a substrate prior to inkjet printing thereon, the aqueous composition having at least 5% solids and up to and including 70% solids, and a dynamic viscosity of at least 30 centipoise (30 mPa-sec) and up to and including 800 centipoise (800 mPa-sec) as measured at 25°C using a Brookfield spindle viscometer, and the aqueous composition comprises:
• visible light-scattering particles comprising visible lightscattering titanium dioxide particles that have been surface-treated such that the aqueous composition has a stable zeta potential of greater than +10 millivolts, wherein the surface-treated visible light-scattering titanium dioxide particles exhibit a Dso of at least 0.04 pm and up to and including 2 pm, as measured using a particle size analyzer that provides a volume weighted particle size distribution, and the (c) surface-treated visible light-scattering particles are present in an amount of at least 10 weight % and up to and including 40 weight %, based on the total weight of the aqueous composition; (d) particles different from the (c) component, which (d) particles have a Rockwell Hardness of less than or equal to R75 and are present in an amount of at least 0.05 weight % and up to and including 3 weight %, based on the total weight of the aqueous composition;
• a dispersing aid for the (c) surface treated visible light scattering titanium dioxide particles which (f) dispersing aid is a polymer having a protonated nitrogen atom, and is present in an amount of at least 0.2 weight % and up to and including 50 weight %, based on the total weight of the (c) surface- treated visible light scattering titanium dioxide particles.
• an inkjet receiving medium comprises a substrate and a topcoat composition disposed on a surface thereof, which topcoat composition comprises:
• the substrate comprises a transparent or translucent polymeric film
• the topcoat composition has a dry solids coating weight of at least 0.2 g/m 2 and up to and including 2 g/m 2
• the topcoat composition comprises the following (a),
• surface-treated visible light scattering particles comprising surface-treated visible light-scattering titanium dioxide particles, which are present in an amount of at least 6 weight % and up to and including 90 weight %, based on the total weight of the topcoat composition, which surface-treated visible light scattering titanium dioxide particles exhibit a Dso (median) particle size of at least 0.04 pm and up to and including 2 pm, as measured using a particle size analyzer that provides a volume-weighted particle size distribution;
• crosslinkable polymeric material that is different from all of the (a), (b), (c), and (d) components, and which (e) crosslinkable polymeric material is present in an amount of at least 0.1 weight % and up to and including 20 weight %, based on the total weight of the topcoat composition;
• a dispersing aid for the (c) surface-treated visible-light scattering titanium dioxide particles which (f) dispersing aid is a polymer having a protonated nitrogen atom, and is present in the topcoat composition in an amount of at least 0.2 weight % and up to and including 50 weight %, based on the total weight of the (c) surface-treated visible light-scattering titanium dioxide particles.
• a method for providing an inkjet receiving medium according to this invention comprises, in order:
• aqueous composition onto at least one surface of the substrate to provide a topcoat composition on the at least one substrate surface, wherein the aqueous composition has at least 2% solids and up to and including 90% solids, and comprises the following (a), (b), and (c) components:
• the substrate comprises a transparent or translucent polymeric film
• the method comprises disposing the aqueous composition so that the resulting topcoat composition has a dry solids coating weight of at least 0.1 g/m 2 and up to and including 2 g/m 2 , and the aqueous composition has at least 5% solids and up to and including 70% solids, and a dynamic viscosity of at least 30 centipoise (30 mPa-sec) and up to and including 800 centipoise (800 mPa-sec) as measured at 25°C using a Brookfield spindle viscometer, and comprises the following (a), (b), (c), (d), (e), and (f) components:
• visible light-scattering particles comprising visible lightscattering titanium dioxide particles, which have been surface-treated and that exhibit a Dso (median) particle size of at least 0.04 pm and up to and including 2 pm, as measured using a particle size analyzer that provides a volume-weighted particle size distribution, and which (c) surface-treated visible light scattering titanium dioxide particles are present in an amount of at least 10 weight % and up to and including 40 weight %, based on the total weight of the aqueous composition;
• crosslinkable polymeric material that is different from all of the (a), (b), (c), and (d) components, and which (e) crosslinkable polymeric material is present in an amount of at least 0.2 weight % and up to and including 8 weight %, based on the total weight of the aqueous composition;
• a dispersing aid for the (c) surface-treated visible-light scattering titanium dioxide particles which (f) dispersing aid is a polymer having a protonated nitrogen atom, and is present in an amount of at least 0.2 weight % and up to and including 50 weight %, based on the total weight of the (c) surface- treated visible light-scattering titanium dioxide particles.
• a method for inkjet printing according to this invention comprises, in order:
• topcoat composition disposed on a surface thereof, which topcoat composition comprises the following (a), (b), and (c) components:
• the substrate comprises a transparent or translucent polymeric film
• the topcoat composition has a dry solids coating weight of at least 0.2 g/m 2 and up to and including 2 g/m 2
• the topcoat composition comprises the following (a), (b), (c), (d), (e), and (f) components:
• visible light-scattering particles comprising visible lightscattering titanium dioxide particles that have been surface-treated and that exhibit a Dso (median) particle size of at least 0.04 pm and up to and including 2 pm, as measured using a particle size analyzer that provides a volume-weighted particle size distribution, and which (c) surface-treated visible light-scattering titanium dioxide particles are present in an amount of at least 6 weight % and up to and including 90 weight %, based on the total weight of the topcoat composition;
• crosslinkable polymeric material that is different from all of the (a), (b), (c), and (d) components, and which (e) crosslinkable polymeric material is present in an amount of at least 0.1 weight % and up to and including 20 weight %, based on the total weight of the topcoat composition;
• a dispersing aid for the (c) surface-treated visible-light scattering titanium dioxide particles which (f) dispersing aid is a polymer having a protonated nitrogen atom and is present in the topcoat composition in an amount of at least 0.2 weight % and up to and including 50 weight %, based on the total weight of the (c) surface-treated visible light-scattering titanium dioxide particles.
• a method of the present invention for providing an inkjet- printed article comprises, in order:
• an inventive inkjet-printed article comprises: a substrate comprising a surface; a topcoat composition disposed on the substrate surface, the topcoat composition comprising the following (a), (b), and (c) components:
• the present invention provides a means for providing a relatively - thin, white (opaque) background on various substrates, on which high quality inkjet-printed layers or images can be provided at high printing speeds
• These inkjet-printed layers or images exhibit excellent adhesion with the white background layer as well as excellent adhesion of the white background to the substrate.
• aqueous compositions to pre-treat or provide a topcoat to a substrate to give it an opaque “white” coating or image (pattern) before inkjet printing is carried out.
• aqueous compositions have the unique features described herein, that is, (a) one or more water-soluble salts of a multivalent metal cation, (b) suitable water-soluble or water-dispersible polymeric binder materials, and (c) surface-treated visible light-scattering particles.
• the resulting inkjet receiving media provided using the present invention can exhibit an opacity of at least 30% as determined by the TAPPI 425 OP-16 test, and a colorimetry defined by an a* value of at least -5 and to and including +5 and a b* value of at least -5 and to and including +5.
• FIG. 1 shows a partial cross-sectional view of a simple embodiment of an inkjet receiving medium according to the present invention.
• FIG. 2 shows a partial cross-sectional view of still another embodiment of an inkjet receiving medium according to the present invention comprising multiple layers.
• FIG. 3 shows a partial cross-sectional view of an inkjet-printed article according to the present invention.
• aqueous compositions for pre-treating topcoat compositions, aqueous pigment-based inks, and other materials used in the practice of this invention
• singular forms “a,” “an,” and “the” are intended to include one or more of the components (that is, including plurality referents).
• the parameter “acid number” (also known as acid value) is defined as the milligrams (mg) of potassium hydroxide required to neutralize 1 g of the described acidic polymer.
• aqueous in aqueous compositions, aqueous organic pigment dispersions, and aqueous pigment-based inks according to the present invention means that the water content is greater than 60 weight %, or at least 80 weight % based on the total weight of all solvents. Thus, water is the predominant solvent in such compositions.
• Rockwell Hardness values for many polymeric materials can be learned from literature published on-line by Plastics International (htp ' // w w . lasticsi n tL co ) and the values can be measured according to ASTM D785-51.
• Median particle size (Dso) as equivalent spherical diameter (ESD) particle size, in micrometers (pm), can be determined using a Horiba Particle Size Distribution Analyzer (Horiba Semiconductor) using procedures desired for use with this instrument, which analyzer provides a volume-weighted particle size distribution.
• the term D95 or the 95 th percentile particle size refers to the classified particle size distribution such that 95% of the particles have diameters smaller than the indicated diameter.
• D50 or the 50 th percentile particle size (or median particle size) refers to the classified particle size distribution such that 50% of the particles have diameters smaller than the indicated diameter.
• Such particle size measurements can be made using either laser diffraction (static) techniques or dynamic light-scattering techniques.
• the D50 and any D95 particle size values were obtained using a commercially available Horiba particle size analyzer (Model LA- 920) that provides a particle size value from a volume weighted particle size distribution.
• ⁇ particle size measuring techniques and equipment are known in the art also.
• laser diffraction techniques will also provide a volume weighted particle size distribution.
• Dynamic light-scattering techniques will provide an intensity -weighted particle size distribution.
• One such device for this purpose is aNanotrac 150 NPA ultrafine particle analyzer (Microtrac, Inc.). Standard procedures for using such a device are described in National Institute of Standards and Technology (NIST) Special Publication 1200-6, Measuring the Size of Nanoparticles in Aqueous Media Using Batch-Mode Dynamic Light-Scattering NIST-NCL Joint Assay Protocol, PCC-1 Version 1.2, May 2015 and in ISO 22412:2017 Particle Size Analysis- Dynamic Light-Scattering (DLS).
• NIST National Institute of Standards and Technology
• Zero-Zeta potential can be measured for purposes of this invention using a "Malvern Zetasizer Nano-ZS” (ZEN) apparatus (Malvern Pananalyticals). Zeta potential is obtained using this equipment from the electrophoretic mobility of the measured particles. Samples are analyzed in an undiluted state. Zeta potential is measured using a combination of the measurement techniques: Electrophoresis and Laser Doppler Velocimetry, sometimes called Laser Doppler Electrophoresis. This method measures how fast a particle moves in a liquid when an electrical field is applied that is, it measures the particle velocity.
• water-soluble when used in reference to salts of multivalent metal cations refers to a solubility in water of at least 0.5 g of salt in 100 ml of water at 20°C.
• Dynamic viscosity can be measured by any of well-known techniques. Preferred methods include measurement of the timing of mass flow through a capillary as in a capillary viscometer, or measurement of ball drop velocity through a fluid, using for example a rolling ball viscometer. Both a capillary flow viscometer and a commercially available Anton Paar Automated MicroViscometer (AMVn) employing the rolling ball technique can be used to measure the dynamic viscosities reported herein. All dynamic viscosity values disclosed herein were measured under gravity induced shear at approximately 24°C to 26°C.
• the Wilhelmy plate method is a well-known technique for measuring the static surface tension of a fluid at a solid interface.
• the technique involves a plate of known dimensions, typically selected from a roughened platinum alloy, suspended from a balance. The plate is contacted with a fluid of interest and a vertical force is applied to the plate to form a liquid meniscus between the fluid and plate.
• the resulting surface tension is given according to equation (1):
• G F / L cos(0) where ⁇ 5 is the surface tension of the liquid, F is the force acting on the balance (milli-Newtons / meter), L is the wetted length of the plate in millimeters, and 0 is the contact angle between the plate and fluid.
• the roughened platinum results in a contact angle very close to zero and the cosine of 0 goes to 1.
• a complete theoretical treatment of the method can be found in, for example, “A Method for Determining Surface and Interfacial Tension Using a Wilhelmy Plate,” Colloid and Polymer Science, 255 (7), pages 675-681.
• a number of commercially available instruments are known for measuring surface tension, however, the instrument used to report surface tension values in the present invention is a Kriiss Model KI OST tensiometer.
• visible light-scattering particles refers to pigments or other water-insoluble particles that uniformly scatter visible light such that, when present as a uniform layer on a surface, the layer will appear white and block the transmission of light from the underlying surface. The degree to which the layer hides the underlying surface determines the relative “opacity” of the layer.
• the opacity of a printed white ink layer is commonly defined as the ratio of the CIE tristimulus value (Y) of the white layer measured over a black background (Yt>) to the same measurement of the white layer over a white background (Y w ).
• Y CIE tristimulus value
• Y w white background
• the opacity of an inkjet receiving medium according to the present invention can also be defined as the ratio of the visual reflectance of a coated white topcoat composition used in the present invention measured over a black background (Rb), to the same measurement of the same coated white topcoat composition over a white background (Rw).
• This standard opacity parameter is described in more detail by consulting the TAPPI standard for opacity that can be reviewed on-line at TAPPI.org or in various publications. This opacity parameter was measured and used for all of the working examples shown below.
• CIELAB L*, a*, and b* values described herein have the known definitions according to CIE 1976 color space or corresponding later known published versions of color space and are determined using a standard D65 illuminant and known procedures. These values can be used to express a color as three numerical values, L* for the lightness (or brightness) of the color, a* for the green-red component of the color, and b* for the blue-yellow component of the color values.
• polymer is used to describe compounds with relatively large molecular weights formed by linking together many small reacted monomers. As the polymer chain grows, it folds back on itself in a random fashion to form coiled structures. With the choice of solvents, a polymer can become insoluble as the chain length grows and become polymeric particles dispersed in the solvent medium. These particle dispersions can be very stable and useful in topcoat compositions described for use in the present invention. In this invention, unless indicated otherwise, the term “polymer” refers to a noncrosslinked material.
• crosslinked polymeric particles differ from the noncrosslinked polymeric particles in that the latter can be dissolved in certain organic solvents of good solvating property whereas the crosslinked polymeric particles may swell but do not dissolve in the organic solvent because the polymer chains are connected by strong covalent bonds.
• copolymer refers to polymers composed of two or more different repeating or recurring units that are arranged along or pendant to the polymer backbone.
• backbone refers to the chain of atoms in a polymer to which a plurality of pendant groups can be attached.
• An example of such a backbone is an “all carbon” backbone obtained from the polymerization of one or more ethylenically unsaturated polymerizable monomers.
• Recurring units in some of the polymers described herein are generally derived from the corresponding ethylenically unsaturated polymerizable monomers used in a polymerization process, which ethylenically unsaturated polymerizable monomers can be obtained from various commercial sources or prepared using known chemical synthetic methods.
• the repeating units in the active polymer can be the result of subsequent chemical reactions with the original repeating units used to make the polymer.
• poly (vinyl alcohol) is derived from the hydrolysis of preformed poly(vinyl acetate), which in turn was made by polymerizing vinyl acetate.
• weight % refers to the amount of a component or material based on the total weight of an aqueous composition, aqueous formulation, or dry layer.
• the term “layer” or “coating” can consist of one disposed or applied layer or a combination of several sequentially disposed or applied layers, such as a combination of sub-layers. Unless otherwise noted, such layers or coatings are non-porous and contiguously cover the specific area of the substrate to which they are applied.
• Percent (%) solids refers to the percentage by weight of nonvolatile materials in a composition or solution, which can be determined using known gravimetric procedures.
• aqueous compositions described herein can be used to provide opaque inkjet-printable media (“inkjet receiving media”) that can be advantageously used in aqueous inkjet printing methods, including those utilizing high-speed inkjet printing systems and anionically-stabilized aqueous pigmentbased inks.
• inkjet receiving media opaque inkjet-printable media
• aqueous pre-treatment compositions (or “aqueous topcoat compositions” or simply “aqueous compositions”) according to the present invention generally have a solids content of at least 2% or at least 5%, and up to and including 70%, or up to and including 90%. Flexographic and gravure coating and inkjet printing techniques may require different optimal % solids to obtain the most desirable layers or patterns of topcoat compositions at the targeted opacities and dried thicknesses according to the present invention.
• the aqueous composition according to this invention can have a dynamic viscosity, as measured at 25°C using Brookfield spindle viscometer (Model LVDV+, using spindle SC4-18) that can be obtained commercially, of less than or equal to 2000 centipoises (2000 mPa-sec) or of at least 30 centipoises (30 mPa-sec) and up to and including 800 centipoises (800 mPa-sec).
• Brookfield spindle viscometer Model LVDV+, using spindle SC4-18
• Such viscometers having necessary spindle sets can be obtained from various commercial sources.
• the aqueous compositions should comprise three essential (a), (b), and (c) components as defined below, in order to achieve the advantages of a thin opaque coating as described herein for the inkjet receiving media of the present invention.
• Such aqueous compositions can also include one or more of the optional (d), (e), and (f) components described below, and in some particularly useful embodiments, at least the (e) and (f) components are present with the essential (a), (b), and (c) components, and in other embodiments, all of the (d), (e), and (f) components are present with the essential (a), (b), and (c) components.
• the aqueous composition should contain (a) one or more water-soluble salts of a multivalent metal cation as an essential component. Mixtures of such salts having the same multivalent metal cation, and mixtures of salts having different multivalent cations can be used, in any desired proportion. Generally, each of these salts is colorless and non-reactive with other materials in the aqueous compositions.
• Useful (a) one or more water-soluble salts can comprise one or more multivalent cations such as magnesium (+2), calcium (+2), barium (+2), zinc (+2), or aluminum (+3), or mixtures thereof.
• the magnesium (+2), calcium (+2), and barium (+2) cations, or combinations thereof, are particularly useful, in combination with suitable counterions.
• Examples of useful (a) one or more water-soluble salts of a multivalent metal cation include but are not limited to, calcium chloride, calcium acetate, calcium nitrate, magnesium chloride, magnesium acetate, magnesium nitrate, barium chloride, barium nitrate, zinc chloride, zinc nitrate, aluminum chloride, aluminum hydroxychloride, and aluminum nitrate. Hydrated versions of these salts can also be used. Other useful (a) water-soluble salts would be readily apparent to a skilled artisan.
• Particularly useful (a) water-soluble salts of a multivalent metal cation comprise one or more of CaCh, Ca(CH3CO2)2, MgCh, Mg(CH 3 CO 2 )2, Ca(NO 3 )2, or Mg(NO 3 )2, or hydrated versions of these salts.
• the amount of the (a) water-soluble salts of multivalent metal cations in the aqueous composition according to the present invention can be sufficient to provide at least 0.1 weight %, at least 0.5 weight %, or even at least 1 weight % and up to and including 25 weight % or up to and including 30 weight % solids, based on the total weight of the aqueous composition.
• binder materials can include but are not limited to poly(vinyl alcohol), polyethylene imine (including protonated polyethylene imine), polyethylene oxide, polyvinyl amine, copolymers derived at least in part from vinyl alcohol and ethylene oxide, copolymers derived at least in part from vinyl amine and vinyl alcohol, poly(vinyl pyrrolidone), cellulose materials (including cellulose and derivatives thereof, such as hydroxy cellulose), gelatin and derivatives thereof, starches, cationic polyelectrolytes, polyurethanes, and silanol-modified poly(vinyl alcohol). Combinations of two or more of such binder materials can also be used. Such binder materials are generally capable of absorbing water and additionally capable of forming a continuous phase solution.
• a useful (b) nonionic or cationic water-soluble or water-dispersible polymeric binder material can be an acetylacetate-modified poly(vinyl alcohol).
• such (b) components in the resulting topcoat composition provide resistance to wet abrasion and increased cohesion of the dried layer.
• the (b) one or more nonionic or cationic water- soluble or water-dispersible polymeric binder materials can comprise at least a polyvinyl amine, a polyethylene imine, a polyvinyl alcohol, a copolymer derived at least in part from vinyl amine and vinyl alcohol, or a combination of two or more of these binder materials.
• the (b) one or more nonionic or cationic water- soluble or water-dispersible polymeric binder materials can be chosen from polyvinyl alcohol, a polyethylene oxide, a polyvinyl amine, a copolymer derived from at least in part from vinyl alcohol and ethylene oxide, a copolymer derived at least in part from vinyl amine and vinyl alcohol, or a combination of two or more of these binder materials.
• Useful cationic polyelectrolytes that can be used in this manner can comprise amidine moieties, polyamide-epichlorohydrin polymers, polyamine solution polymers, as described in Cols. 9-10 of U.S. Patent 9,067,448 (Dannhauser et al.).
• Useful polyurethanes for this purpose can be dispersions of polyurethane particles in aqueous medium, for example as described also in U.S. Patent 9,067,448 (Col. 10, lines 36-48).
• Useful silanol-modified poly(vinyl alcohol)s are also described in U.S. Patent 9,067,448 (Col. 10, lines 49-68).
• the (b) one or more nonionic or cationic water- soluble or water-dispersible polymeric binder materials can be chosen so that they are also useful to surface treat or form the (c) surface-treated visible lightscattering particles as described in more detail below.
• Particularly useful binder materials useful for this purpose include but are not limited to, polymers having a protonated nitrogen atom such as polyvinyl amine, a protonated polyethylene imine, and a copolymer derived at least in part from vinyl amine and vinyl alcohol.
• one or more nonionic or cationic water-soluble or water- dispersible polymeric binder materials can be present in the aqueous composition in an amount of at least 0.1 weight %, or at least 1 weight %, and up to and including 8 weight % or up to and including 30 weight %, based on the total weight of the aqueous composition.
• the aqueous composition should include as another essential component, (c) visible light-scattering particles that have been surface- treated (that is “(c) surface-treated visible light scattering particles”) as described herein, having a Dso (median) particle size of at least 0.04 pm and up to and including 0.5 pm or up to and including 2 pm, which is determined as described above using a particle analyzer that provides a volume-weighted particle size distribution.
• some embodiments of visible light-scattering particles and surface-treated visible light-scattering particles may be obtained having a Dso (median) particle size greater than 2 pm, in which case such particles are outside the scope of the present invention, even though they still pass the “salt” test and provide the desired zeta potentials in the aqueous compositions.
• Such larger visible light-scattering particles can be desirably subjected to milling to reduce their Dso (median) particle size to 2 pm or less.
• Useful materials that can serve as the visible light-scattering particles include but are not limited to, silicon dioxide, zinc oxide, titanium dioxide, zirconium oxide, aluminum oxide, barium sulfate, magnesium oxide, or a combination of two or more of these materials. All of these visible lightscattering particles can be surface-treated in a manner noted below. Particularly useful (c) surface-treated visible light-scattering particles comprise surface-treated visible light-scattering titanium dioxide particles. It is possible to surface treat the visible light-scattering particles using one or more of the (f) dispersing aids described below. This can be accomplished by mixing the visible light-scattering particles with one or more (f) dispersing aids in a suitable solvent, such as water.
• the order of addition can vary.
• the visible light-scattering particles can be dispersed into the solvent first, followed by the addition of the (f) dispersing aid.
• the opposite order of addition can also be effective.
• the (a) one or more water-soluble salts of a multivalent cation be added after the addition of both the (c) surface-treated visible light-scattering particles and the (f) dispersing aid.
• the resulting (c) surface-treated visible-light scattering particles can also be provided with a shell using a positively- charged solid material to render the surface charge of the particles cationic.
• aluminum oxide can be used to surface treat visible lightscattering titanium dioxide particles in an amount of at least 1 weight % and up to and including 10 weight %, based on the total weight of the surface-treated visible light-scattering titanium dioxide particles.
• the effect of such surface treatment is to give the aqueous composition according to this invention containing the (c) surface-treated visible light-scattering particles, a stable zeta potential of greater than +4 millivolts (mV), or greater than +5 mV, or even greater than + 10 mV, over the intended life of the aqueous composition.
• mV millivolts
• the (c) surface-treated visible light-scattering particles can be present in an amount of at least 5 weight % or at least 10 weight %, and up to and including 40 weight % or up to and including 60 weight %, based on the total weight of the aqueous composition.
• the three essential (a), (b), and (c) components noted above can be mixed in suitable proportions, at a suitable temperature, and in a suitable order to obtain an aqueous composition according to the present invention.
• Representative examples of useful aqueous compositions are provided below in the working examples.
• the aqueous compositions according to this invention can optionally comprise (d) particles having a Rockwell Hardness of less than or equal to R90, or less than or equal to R75. Rockwell Hardness can be determined as described above. These (d) particles are different from the (c) component described above.
• Useful (d) particles can be chosen from various wax particles and other sufficiently soft polymer particles. Specific examples include but are not limited to, particles of polyethylene, polytetrafluoroethylene), polypropylene, ethylene bis-stearamide, synthetic hydrocarbon waxes, carnauba wax, and a combination of two or more types of these materials.
• Some particularly useful (d) particles comprise domains of a (i) first organic polymer and domains of a (ii) second organic polymer, both of which organic polymers.
• the domains of the (ii) second organic polymer are dispersed, uniformly or non-uniformly, within the domains of the (i) first organic polymer.
• the melting point of the (i) first organic polymer is lower than (by at least 30°C) the melting point of the (ii) second organic polymer.
• the weight ratio of the (i) first organic polymer to the (ii) second organic polymer is chosen such that the (d) particles have a density of at least 1.0 g/ml and up to and including 1.50 g/ml, or more likely of at least 1.05 g/ml and up to and including 1.35 g/ml, or even of at least 1.05 g/ml and up to and including 1.20 g/ml.
• Particle density can be determined using known procedures and equipment such as gas pycnometry or mercury porosimetry.
• Useful polymeric materials that can form the (i) first organic polymer domains include but are not limited to, a polyethylene, a polypropylene, ethylene bi-stearamide, polyethylene-polypropylene copolymer, carnauba wax, a synthetic hydrocarbon wax (especially those produced by the Fischer-Tropsch process as described in Industrial Waxes, Vol. 1 by H. Bennett), a polyamide, and a combination of two or more of these materials.
• Useful polymeric materials that can form the (ii) second organic polymer domains include but are not limited to, polytetrafluoroethylene) (PTFE or Teflon).
• the mode average equivalent spherical diameter (ESD) particle size of the (d) particles can be at least 2 pm or at least 3 pm, and up to and including 8 pm, or up to and including 12 pm.
• the ESD of such particles can be adapted so that it is at least 0.1 pm greater, or at least 0.2 pm greater, than the sum of the dry thickness of the topcoat composition (described below) and any dry inkjet-printed image or layer (described below).
• the amount of useful (d) particles present in the aqueous composition is generally at least 0.02 weight % or at least 0.05 weight %, and up to and including 3 weight, % or up to and including 5 weight %, based on the total weight of the aqueous composition.
• Another optional but desirable component in the aqueous composition is a (e) crosslinkable polymeric material that is different from all of the (a), (b), (c), and (d) components.
• Useful (e) crosslinkable polymeric materials of this type include those described in [0029] and [0030] of U.S. Patent Application Publication 2011/0279554 (Dannhauser et al.).
• useful (e) crosslinkable polymeric materials can include but are not limited to, gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl amine, polyethyleneimine, starch, hydroxycellulose materials, and derivatives of such materials. Mixtures of two or more of such (e) crosslinkable polymeric materials can be used if desired.
• crosslinking agents in the aqueous composition to promote crosslinking of the (e) crosslinkable polymeric materials that are present.
• the identity and amount of crosslinking agent will depend upon the choice of (e) crosslinkable polymeric material and its reactivity with the crosslinking agent, the number of crosslinking sites available, its compatibility with other materials in the aqueous composition, and manufacturing constraints such as solution pot life and coating drying speed.
• crosslinking agents include but are not limited to, glyoxal, CARTABOND® TSI and EPI (Clariant), SEQUAREZTM 755 (Omnova), glutaraldehyde sodium bisulfate complex (Aldrich), Sunrez 700 M and 700C (Omnova), bis(vinyl) sulfone), bis(vinyl)sulfone methyl ether, adipoyl dihydrazide, epichlorohydrin polyamide resins, and urea-formaldehyde resin.
• the amount of one or more (e) crosslinkable polymeric materials in the aqueous composition according to this invention can be at least 0.1 weight % or at least 0.2 weight % and up to and including 8 weight % or up to and including 30 weight %, based on the total weight of the aqueous composition.
• Yet another optional but desirable component in the aqueous composition is a (f) dispersing aid for the (c) surface-treated visible lightscattering particles, which (f) dispersing aid is cationic in cumulative charge and is different from the (a) one or more water-soluble salts of a multivalent cation but which (f) dispersing aid can be the same or different from the (b) one or more nonionic or cationic water-soluble or water-dispersible polymeric binder materials used in the aqueous composition.
• the (b) one or more nonionic or cationic water-soluble or water-dispersible polymeric binder materials can also serve as a (f) dispersing aid or “surface treating” material for providing the surface treatment of the (c) surface-treated visible light-scattering particles.
• Useful (f) dispersing aids can be polymers having at least one protonated nitrogen atom including but not limited to, a protonated polyvinyl amine, a protonated polyethylene imine, a copolymer derived at least in part from vinyl amine, or a combination of two or more of such materials.
• Protonated polyvinyl amine and copolymers derived at least in part from vinyl amine are particularly useful.
• a useful protonated polyvinyl amine is described in Col. 10 (lines 21ff) of U.S. Patent 9.067,448 (noted above), and a commercially available example is identified as CATIOFAST® 159(A) (BASF).
• a protonated polyethylene imine can be a particularly useful (f) dispersing aid in some embodiments, and commercially available materials of this type are the Lupasol® line of polymers available from BASF. It will be appreciated by one skilled in the art that polyethylene images and polyvinyl amines can exist in either a protonated or unprotonated form depending upon the pH of the aqueous composition. To be useful in the present invention, the pH of the aqueous composition can be adjusted such that at least some or all of the nitrogen atoms in the noted polymers or copolymers are protonated.
• the (f) dispersing aid can be present in an amount of at least 0.2 weight % or least 1 weight %, and up to and including 15 weight % or up to and including 20 weight % or even up to and including 50 weight %, based on the total weight of the (c) surface-treated visible light-scattering particles.
• the amount of the (f) dispersing aid present in the aqueous composition may be greater than the amount needed for sufficient surface treatment of the visible light-scattering particles.
• the aqueous composition can further comprise one or more of the following optional materials: a surfactant, an anti-corrosion compound, a biocide, a preservative, an antifoam agent, or any combination of two or more of these materials.
• the aqueous compositions can be prepared by suitably mixing the essential (a), (b), and (c) materials along with various optional components and materials described above in a desired mixing order and with suitable equipment, in an aqueous medium that is predominantly water in amounts to provide the % solids noted above. At least 50 weight %, or at least 70 weight %, or even at least 90 weight % of the aqueous medium is comprised of water, based on the total weight of all solvents in the aqueous medium.
• Some particularly useful embodiments according to the present invention include aqueous compositions for pre-treating a substrate prior to inkjet printing thereon, each aqueous composition having least 5% solids and up to and including 50% solids or up to and including 70% solids, and a dynamic viscosity of at least 30 centipoise (30 mPa-sec) and up to and including 800 centipoise (800 mPa-sec), or up to and including 1200 centipoise (1200 mPa-sec), or up to and including 2000 centipoise (2000 mPa-sec) as measured at 25°C using a Brookfield spindle viscometer, the aqueous composition comprising the following components (a) through (f):
• (c) visible light-scattering particles comprising visible lightscattering titanium dioxide particles, which have been surface-treated such that the aqueous composition has a stable zeta potential of greater than +4 millivolts (mV) or greater than +10 millivolts (mV), wherein the (c) surface-treated visible light scattering titanium dioxide particles exhibit a Dso (median) particle size of at least 0.2 pm and up to and including 0.5 pm, as measured using a particle size analyzer that provides a volume-weighted particle size distribution, and are present in an amount of at least 5 weight % or at least 10 weight %, and up to and including 40 weight % or up to and including 60 weight %, based on the total weight of the aqueous composition;
• crosslinkable polymeric material that is different from all of the (a), (b), (c), and (d) components, and which (e) crosslinkable polymeric material is present in an amount of at least 0.1 weight % or at least 0.2 weight %, and up to and including 8 weight % or up to and including 30 weight %, based on the total weight of the aqueous composition;
• a dispersing aid for the (c) surface-treated visible lightscattering titanium dioxide particles which (f) dispersing aid is a polymer having a protonated nitrogen atom, and is present in an amount of at least 0.2 weight % or at least 1 weight %, and up to and including 20 weight % or up to and including 50 weight %, based on the total weight of the (c) surface-treated visible lightscattering titanium dioxide particles.
• a simple embodiment according to the present invention is inkjet receiving medium 10 having substrate 100 on which topcoat composition 110 is disposed, and substrate 100 and topcoat composition 110 are contiguous or in direct contact with each other.
• substrate 100 can be opaque, semi-transparent, translucent, or transparent, but transparent or translucent or even reflective metallized polymeric films are particularly useful with the opacity described herein that is provided by topcoat composition 110.
• Suitable substrates can be typically planar in nature with two opposing surfaces or supporting sides. Substrates can have a single “layer” or stratum or be composed of multiple layers or strata composed of the same or different materials. In most instances, a substrate comprises a predominant material, such as a transparent polymeric material that is coated or layered with one or more other types of materials such as polymeric coatings or metal layers.
• substrate materials from which substrate 100 can be constructed include but are not limited to, glossy, semi-glossy, or matte coated lithographic offset papers that typically comprise a paper base (support) that has been coated with a clay or similar materials and has undergone surface calendering treatment to provide a desired surface smoothness.
• Such substrates include both glossy coated and matte coated lithographic offset papers and can be obtained from various commercial sources including for example International Paper, Sappi, NewPage, Appleton Coated, Abitibi-Bowater, Mohawk Papers, Verso, Mitsubishi, Norpac, Domtar, and others readily known to a skilled artisan.
• the substrate material can be readily hydrophilic and be capable of absorbing and transferring aqueous pigment-based ink colorants (such as pigment colorants) to the substrate interior prior to the topcoat composition being disposed thereon (such as being coated thereon) with the aqueous compositions described herein.
• a hydrophilic substrate can be porous.
• the substrate can have a hydrophobic surface prior to the opaque topcoat composition being disposed thereon. This hydrophobic surface can be substantially impermeable to water or to an aqueous pigment-based ink composition.
• the topcoat composition can provide an opaque hydrophilic surface relative to the hydrophobic surface of such substrate.
• substrates include coated and uncoated offset papers and other plain papers, as well as any other materials typically used as inkjet receiving media such as resin-coated papers, polyester films, microporous materials such as polyethylene-containing materials, composite films, plain coated and uncoated papers, synthetic papers, photographic paper supports, meltextrusion-coated papers, and laminated papers such as biaxially oriented support laminates such as those described in Col. 6 (line 50) to Col. 7 (line 2) of U.S. Patent 9,067,448 (noted above).
• the substrates mentioned herein are intrinsically opaque, the present invention is particularly useful when opaque substrates are dark in color, in which case the subsequently inkjet-printed image would be difficult to observe without first applying the white opaque aqueous composition of the present invention.
• the surface to be coated can be modified to increase the static surface energy to greater than 45 dynes/cm (or at least 50 dynes/cm and up to and including 60 dynes/cm) prior to disposition of the topcoat composition in order to provide adequate wettability for application of the aqueous composition and formation of the topcoat composition.
• Surface energy modification can be carried out using corona discharge treatment (CDT), plasma discharge treatment, flame ionization treatment, atomic layer deposition, or similar treatments known in the art.
• FIG. 2 illustrates another embodiment according to this invention in which inkjet recording medium 20 comprises support 200 that can be water- impermeable and optional first layer 210 disposed on at least one surface of support 200, which together form substrate 215 for the inkjet receiving medium according to the present invention.
• First layer 210 can comprise a water-based tie layer composition (described below) and is located underneath topcoat composition 220.
• support 200 can be composed of a water-impermeable material such as a transparent or translucent polymeric film, or a co-extrudate or a laminate of two more transparent or translucent polymeric films as referred to above in U.S. Patent 9,067,448 (Cols. 6-7).
• the topcoat composition 220 generally provides excellent adhesion to most support 200 without the need for a separate first-layer 210, there can be supports for which first-layer 210 is useful to enhance the adhesion of topcoat composition 220 to support 200.
• the substrate comprises a transparent or translucent polymeric film, or a co-extrudate or a laminate of two or more transparent or translucent polymeric films. Materials of this type are readily available from various commercial sources.
• First layer 210 can be known in the art as a “tie-layer” and is generally water-based meaning that it is provided from an aqueous formulation and serves to improve the adhesion of topcoat composition 220 to support 200 when it is composed of a hydrophobic material such as a transparent or translucent polymeric film (such as a polyester film) or a polyethylene coated paper.
• a hydrophobic material such as a transparent or translucent polymeric film (such as a polyester film) or a polyethylene coated paper.
• hydrophilic materials useful for composing first layer 210 include but are not limited to, halogenated phenols, partially hydrolyzed vinyl chloride-vinyl acetate copolymers, vinylidene chloride-methyl acrylateitaconic acid terpolymers, vinylidene chloride-acrylonitrile-itaconic acid terpolymers, and glycidyl (meth)acrylate polymers.
• Other useful materials include any polymers, copolymers, reactive polymers and copolymers, and mixtures thereof, that exhibit effective bonding between the topcoat composition and the substrate.
• Water-soluble or water-dispersible polymers that can also be used include but not limited to, poly(vinyl alcohol)s, polyvinyl amine, poly(vinyl pyrrolidone), gelatin and gelatin derivatives, cellulose ethers, poly(oxazoline), poly(vinyl acetamide), partially hydrolyzed poly(vinyl acetate/poly vinyl alcohol), poly(acrylic acid), poly(acrylamide), poly(alkylene oxide)s, sulfonated or phosphonated polyesters or polystyrenes, casein, zein, albumin, chitin, chitosan, dextran, pectin, a collagen derivative, collodion, agar-agar, arrowroot, guar, carrageenan, tragacanth, xanthan, rhamsan, and various polymeric lattices.
• tie-layer materials are polyvinyl alcohols, polyvinyl amine, gelatin or a gelatin derivative, poly(ethyleneimine), an epoxy resin, polyurethanes, polyacrylamides and derivatives or copolymer thereof, and mixtures of any of these materials.
• first layer 210 can be a single discrete layer, it can also comprise two or more water-based sub-layers, each of which comprises the same or different hydrophilic materials described above.
• the total dry coverage of the one or more hydrophilic materials in first layer 210 can be at least 0.05 g/m 2 and up to and including 12 g/m 2 , or at least 0.05 g/m 2 and up to and including 8 g/m 2 , or at least 0.05 g/m 2 and up to and including 3 g/m 2 .
• first layer 210 (or tie-layer) construction and materials are provided in U.S. Patent 9,376,582 (Dannhauser et al.).
• a topcoat composition can be disposed on each of the opposing surfaces of a substrate, and the individual topcoat compositions can be composed of the same or different combinations of materials, can have the same or different average dry thicknesses, or be formed using the same or different processes.
• An inkjet receiving medium prepared according to the present invention can comprise a substrate that has an L* value of 50 or less, or even 40 or less.
• the inkjet receiving medium prepared according to the present invention can have an opacity of at least 30% or of at least 50%, as determined using the TAPPI 425 OP-16 opacity test describes above, and can have a colorimetry defined by an a* value of at least -5 and to and including +5 and a b* value independently of at least -5 and to and including +5, or more likely each of the a* and b* values are independently at least -3 and up to and including +3.
• the topcoat composition can be disposed on the substrate surface in various ways using a number of application methods and means as described in more detailed below.
• the substrate can be disposed on the substrate as a continuously distributed layer, meaning that the layer is generally uniform in coating coverage and there are no intended parts of the substrate surface that are not covered.
• Such layers or coatings can be applied using flexography, gravure, or other known coating techniques and apparatus known in the coating arts.
• the topcoat composition can be disposed on the substrate surface as a pattern, either as a regular (predetermined) or irregular pattern, that can be provided using for example, flexography and suitably patterned flexographic printing sleeves or gravure and suitably engraved gravure cylinders.
• the topcoat composition upon drying (that is, with less than 10 weight % or even less than 5 weight % of aqueous medium remaining), generally has a dry solids coating weight (or coating coverage) of at least 0.1 g/m 2 or at least 0.2 g/m 2 and up to and including 1 g/m 2 , or up to and including 2 g/m 2 , or up to and including 10 g/m 2 .
• the essential (a) one or more water-soluble salts of a multivalent metal cation, as described above, are generally present in an amount of at least 0.4 weight % or at least 15 weight % and up to and including 40 weight %, based on the total weight of the topcoat composition.
• the useful coverage of the topcoat composition will provide, at least 1.2 weight % and up to and including 40 weight % of the multivalent metal cation, based on the total weight of the topcoat composition.
• the (a) one or more water-soluble salts of a multivalent metal cation can be present in an amount sufficient to provide the multivalent cation (such as calcium cation) in the topcoat composition in an amount of at least 0.01 g/m 2 and up to and including 4 g/m 2 .
• the essential (b) one or more nonionic or cationic water-soluble or water-dispersible polymeric binder materials, as described above, can be present in the topcoat composition in an amount of at least 0.5 weight % or at least 2 weight %, and up to and including 30 weight % or up to and including 90 weight %, based on the total weight of the topcoat composition.
• the essential (c) surface-treated visible light-scattering particles as described above are present in the topcoat composition in an amount of at least 6 weight %, and up to and including 50 weight % or up to and including 90 weight %, based on the total weight of the topcoat composition.
• Particularly useful (c) surface-treated visible light-scattering particles comprising surface-treated visible light-scattering titanium dioxide particles, such as aluminum oxide-treated visible light-scattering titanium dioxide particles.
• the (d) particles different from the essential (c) component as described above having a Rockwell Hardness of less than or equal to R90 (or D75) can be present in the topcoat composition in an amount of at least 0.06 weight % or at least 0.5 weight % and up to and including 5 weight %, or up to and including 10 weight %, based on the total weight of the topcoat composition.
• the (d) particles can have an ESD that is at least 0.1 pm greater than sum of the dry thickness of the topcoat composition and the dry thickness of any inkjet-printed image or layer.
• the (e) crosslinkable polymeric material(s) as described above that is also different from all of the (a), (b), (c) and (d) components can be present in the topcoat composition in an amount of at least 0.1 weight % and up to and including 20 weight % or up to and including 30 weight %, based on the total weight of the topcoat composition.
• a crosslinking agent, as described above, can be present also, and the useful amount of such (e) crosslinking agent would be readily apparent to one skilled in the art using routine experimentation.
• the (f) dispersing aid for the (c) surface-treated visible light-scattering particles is cationic in cumulative charge.
• the (I) dispersing aid is different from the (a) one or more water-soluble salts of a multivalent metal cation and can be the same as or different from (b) one or more nonionic or cationic water-soluble or water- dispersible polymeric binder materials.
• Such (I) dispersing aids can be present in the topcoat composition in an amount of at least 0.2 weight % and up to and including 50 weight %, based on the total weight of the (c) surface-treated visible light-scattering particles.
• a useful (f) dispersing aid can be a polymer having a protonated nitrogen atom such as a protonated polyvinyl amine or a protonated polyethylene imine, or a copolymer derived at least in part form a vinyl amine and vinyl alcohol, that can be present in an amount of at least 0.2 weight % and up to and including 50 weight %, based on the total weight of the surface-treated visible light-scattering particles that can be surface-treated visible light-scattering titanium dioxide particles.
• a protonated nitrogen atom such as a protonated polyvinyl amine or a protonated polyethylene imine
• a copolymer derived at least in part form a vinyl amine and vinyl alcohol that can be present in an amount of at least 0.2 weight % and up to and including 50 weight %, based on the total weight of the surface-treated visible light-scattering particles that can be surface-treated visible light-scattering titanium dioxide particles.
• such (f) dispersing aids can be used when the (b) one or more nonionic or cationic water-soluble or water- dispersible polymeric binder materials comprise at least a polyvinyl amine, a polyvinyl alcohol, a protonated polyethylene imine, a protonated polyvinyl amine, or a copolymer derived at least in part from vinyl amine.
• the resulting inkjet recording medium can be used for various purposes, but it is particularly useful for inkjet printing methods to provide a monochrome or multi-chrome (or multicolor) image or layer in an inkjet-printed article.
• Such inkjet-printed articles then can have a substrate and topcoat composition for example as illustrated in each of FIGS. 1 and 2, on which an aqueous-based inkjet printing image or layer is disposed over (for example, directly on) the topcoat composition.
• an inkjet-printed image or layer can be formed by inkjet printing one or more aqueous-based inkjet ink compositions that are described below.
• An aqueous composition (also identified herein as a “topcoat composition formulation”) according to this invention can be used to prepare or form a topcoat composition of the desired opacity on only one or both opposing sides (or surfaces) of a substrate (as described above).
• a substrate is chosen and an aqueous composition according to this invention is formulated and disposed on at least one surface of the substrate and dried to provide a topcoat composition.
• the result of these operations is an inkjet receiving medium according to the present invention useful for inkjet printing according to this invention.
• the procedures and apparatus used to accomplish these operations can be selected from various known techniques and apparatus, including but not limited to spraying, rod coating, blade coating, gravure coating, (direct, reverse, or offset), flexographic coating, size press (puddle and metered), extrusion hopper coating, and curtain coating, using suitable equipment for these purposes.
• a topcoat composition can be disposed on a substrate surface in-line as part of substrate manufacturing (such as a paper making process or a film-forming process).
• the topcoat composition can be disposed on a substrate surface in a separate step after the manufacture of the substrate.
• the topcoat composition can be formed in-line as part of an inkjet printing operation, wherein the aqueous composition is disposed on a substrate surface in a “pre-coating” or “pre-treatment” station prior to printing of aqueous pigment-based inks using a multi-station apparatus.
• Such pre-coating operations can be designed to provide uniform (continuous) coverage of the topcoat composition, or in some instances, only a specific area of the substrate can be provided with the aqueous composition to form a pattern or image. While the disposed topcoat composition can be dried completely before inkjet image printing, complete drying may not be necessary and overall drying of both disposed topcoat composition and inkjet-printed image or layer can be carried out at the same time.
• the topcoat composition can be disposed on the substrate surface in a manner to provide a continuously distributed layer. For example, various application techniques such as gravure coating or flexographic printing can be used to dispose the aqueous composition in a pattern followed by inkjet printing in registration with that pattern.
• Inkjet receiving media can be inkjet printed with one or more aqueous pigment-based inks comprising one or more pigment colorants to provide a pigment-based image or layer. These aqueous pigment-based inks can be printed onto the topcoat composition of the inkjet receiving media designed and prepared as described above.
• the inkjet printing methods according to the present invention can be used for printing periodicals, newspapers, magazines, greeting cards, lottery tickets, plastic wrap, paperboard, advertising, flexible packaging, labels, and other materials that would be readily apparent to one skilled in the art.
• aqueous compositions according to this invention can be useful in inkjet receiving media useful in one or more drop-on-demand (DOD) printing systems
• the advantages of the present invention are particularly evident when the method according to the present invention is carried out using continuous inkjet (CIJ) printing processes and equipment at high printing speeds.
• CIJ printing processes There are several CIJ printing processes known in the art, and the present invention is not limited to a particular CIJ process, but there may be certain CIJ processes that are more useful than others.
• such CIJ processes use one or more aqueous pigment-based inks that are ejected through one or more printheads (containing nozzles) and unprinted aqueous pigment-based ink is collected and recycled through the printing system multiple times until it is used up.
• the CIJ printing system can have incorporated replenisher systems. Details of such CIJ processes and equipment are provided for example in U.S. Patent 8,173,215 (Sowinski et al.).
• each aqueous pigmentbased ink can be ejected or printed from a main fluid supply dedicated to it only, as a continuous stream of the aqueous pigment-based ink that is broken into both printing drops and non-printing drops.
• the non-printing drops of each aqueous pigment-based ink can be collected using suitable collecting means such as a “catcher” and returned to its respective main fluid supply.
• This entire scenario can be carried out using a single (first) aqueous pigment-based ink alone, or in combination with one or more “additional” aqueous pigment-based inks having the same or different “colors” or hues as the first aqueous pigment-based ink.
• the multiple aqueous pigment-based inks are then inkjet printed in a chosen sequence that can be controlled by software and digital input, in a controlled manner, to provide a multicolor inkjet-printed image on the surface of the inkjet receiving medium.
• Each of the one or more aqueous pigment-based inks can be supplied from respective main fluid supplies as one or more continuous streams, and each of these one or more continuous streams can be broken into both printing drops and non-printing drops that are collected and returned from the each of the one or more continuous streams to the respective main fluid supplies.
• inkjet printing of an aqueous “colorless” or aqueous pigment-free ink composition or fluid can be carried out in place of, simultaneously with, or sequentially with inkjet printing of a colored aqueous pigment-based ink(s).
• a colorless lacquer or colorless ink composition can be applied over a single- or multi-color pigment-based image or layer.
• the inkjet receiving media according to the present invention can be used in such printing processes.
• a fluid system contains an ink resistivity measurement cell through which an aqueous pigment-based ink passes as it is being recirculated through the ink handling portion of the system, including the printhead.
• a calculation means determines the resistance of the ink resistivity cell.
• a logic and control unit responsive to the calculation means, controls the transfer of aqueous pigmentbased ink from a supplemental “ink” supply and the transfer of an aqueous particle-free fluid (“carrier fluid”) from a replenishment carrier fluid supply to the system main fluid supply, to maintain desired resistivity in the aqueous inkjet ink composition.
• the volume of the aqueous pigment-based ink is monitored by a float valve position, and when a predetermined volume has been depleted, the predetermined volume is replaced by either aqueous pigment-based ink from the supplemental “ink” supply or by carrier fluid from the replenishment carrier fluid supply.
• the first and any additional aqueous pigment-based inks can be replenished, respectively, with first and any additional aqueous pigment-based inks.
• the method according to the present invention can further comprise replenishing a main fluid supply with an aqueous particle- free fluid that has a dynamic viscosity of less than or equal to 5 centipoise (5 mPa- sec) at 25°C as measured using a rolling ball viscometer.
• the method according to the present invention is carried out using a plurality of printing drops formed from a continuous fluid stream, and non-printing drops of a different volume than the printing drops are diverted by a drop deflection means into a “catcher” for collection and recirculation. Details about such CIJ printing systems and equipment are provided for example in U.S.
• Patents 6,588,888 (Jeanmaire et al.), 6,554,410 (Jeanmaire et al.), 6,682,182 (Jeanmaire et al.), 6,793,328 (Jeanmaire et al.), 6,866,370 (Jeanmaire et al.), 6,575,566 (Jeanmaire et al.), and 6,517,197 (Hawkins et al.), and in U.S. Patent Application Publication 2002/0202054 (Jeanmaire et al.).
• an aqueous pigment-based ink can be printed using an apparatus capable of controlling the direction of the formed printing drops and non-printing drops by asymmetric application of heat to the fluid stream that initializes drop breakup and serves to steer the resultant drop as described for example in U.S. Patents 6,079,821 (Chwalek et al.) and 6,505,921 (Chwalek).
• Useful agitation, heated supply, printhead, and fluid filtration means for CIJ printing are described for example in U.S. Patent 6,817,705 (Crockett et al.).
• FIG. 1 of U.S. Patent 8,764,161 (Cook et al).
• Other useful details concerning CIJ printing apparatus and printhead fabrication are described for example in U.S. Patents 6,943,037 (Anagnostopoulos et al).
• the printing methods according to the present invention can be carried out using a continuous high-speed commercial inkjet printer, for example in which the inkjet printer applies colored images using one or more different print heads such as full-width print heads with respect to the inkjet receiving media, in sequence, in which the different colored parts of images are to be registered.
• Continuous inkjet (CI J) printing uses a pressurized ink source that produces a continuous stream of printing drops (droplets) from a main fluid supply for each aqueous pigment-based ink, or a continuous stream that is broken into both printing drops and non-printing drops.
• Continuous inkjet printers can utilize electrostatic charging devices that are placed close to the point where a filament of working inkjet composition breaks into individual drops that are electrically charged and then directed to an appropriate location by deflection electrodes having a large potential difference. Where no color image is desired, the non-printing drops can be deflected into an ink-capturing mechanism and disposed of or recycled by returning them to the original main fluid supply.
• the printing drops are not deflected but are allowed to strike the topcoat composition of the inkjet receiver medium in designated locations.
• deflected printing droplets can be allowed to strike the topcoat composition of the inkjet receiver medium while non-deflected non-printing drops can be collected and returned to the main fluid supply.
• the method according to the present invention can comprise printing one or more aqueous pigment-based inks onto the topcoat composition of an inkjet receiving medium to provide a pigment-based image in a predetermined pattern using an inkjet deposition system in response to electrical signals, and this predetermined pattern can be inkjet-printed in registration with the same pattern provided by the topcoat composition.
• printing one or more aqueous pigment-based inks onto the topcoat composition that is disposed on the substrate surface as a pattern can be accomplished in a manner to provide a pigment-based image in registration with the pattern of the topcoat composition using a suitable inkjet deposition system.
• the topcoat composition can be disposed on the substrate surface in a pattern using flexographic printing
• the B) inkjet printing of one or more aqueous pigment-based inks can be carried out in-line at different stations of a multi-station apparatus onto the pattern of the topcoat composition to provides a pigment-based image in registration with the pattern of the topcoat composition.
• the substrate can comprise a hydrophobic surface prior to the topcoat composition being formed thereon, which hydrophobic surface is impermeable to water or to an aqueous ink composition, and in which the topcoat composition provides a hydrophilic surface relative to the hydrophobic surface of the substrate.
• Such substrates can comprise a transparent, translucent, or metallized polymeric film, or a co-extrudate or a laminate of two or more transparent, translucent, or metalized polymeric films.
• An aqueous pigment-based ink useful according to the present invention can be prepared from a suitable aqueous dispersion of one or more particulate pigments using known dispersants and dispersing means.
• the resulting aqueous pigment-based ink can be mixed with one or more humectants or co-solvents and the components can be formulated in an aqueous medium (predominantly water) to provide an aqueous pigment based inkjet ink having a dynamic viscosity of less than or equal to 10 centipoise (10 mPa-sec), or less than or equal to 5 centipoise (3 mPa-sec), or even less than or equal to 3 centipose (1.5 mPa-sec), all measured at 25°C as described above.
• Each aqueous pigment-based ink useful in the practice of this invention typically comprises one or more particulate, organic or inorganic pigment colorants that will provide the desired color or hue such as black, green, red, yellow, blue, violet, magenta, cyan, white, brown, grey and other hues known in the art. Pigment colorants can be present individually or in mixtures in each aqueous pigment-based ink.
• aqueous pigment-based inks useful in the present invention comprise one or more pigment colorants selected from a cyan pigment, a magenta pigment, a yellow pigment, a black pigment, a green pigment, an orange pigment, a white pigment, a red pigment, a blue pigment, a violet pigment, and a combination of any of these pigment colorants, and any or all of these pigments can be anionically-stabilized as described below.
• organic and inorganic pigment colorants can be used individually or in combination.
• a carbon black pigment can be combined with a colored pigment such as a cyan copper phthalocyanine or a magenta quinacridone pigment.
• Useful pigments are described for example in U.S. Patents 5,026,427 (Mitchell et al.), 5,141,556 (Matrick), 5,160,370 (Suga et al.), and 5,169,436 (Matrick).
• Useful pigment colorants can be accompanied by suitable polymeric or non-polymeric dispersants that are well known in the art (as described above), or the pigment colorants can be self-dispersing and thus dispersible and stable in the aqueous pigment-based ink without the use of dispersants because of the presence of appropriate surface groups. Examples of useful self-dispersing pigment colorants are described in Col. 11 (lines 49-53) of U.S. Patent 8,455,570 (noted above).
• pigment colorants used in the present invention are stabilized with anionic moieties (that is, “anionically- stabilized pigments”).
• anionic moieties that is, “anionically- stabilized pigments”.
• Such pigment colorants can be purchased from various commercial sources, and a skilled worker would know which pigment colorants of this type could be used in the present invention.
• some of such pigment colorants are self-dispersing pigments that are dispersible and stable without the use of a polymeric or molecular dispersant or surfactant.
• Useful pigment colorants can have a median particle diameter of less than 150 nm and more likely less than 100 nm or even less than 50 nm.
• median particle diameter refers to the Dso of the classified particle size distribution such that 50% of the volume of the pigment colorant particles is provided by particles having diameters smaller than the indicated diameter.
• a laser light-scattering device as described above, can be used to measure the particle size distributions.
• Organic or inorganic pigment colorants can be present in each aqueous pigment-based ink in an amount of at least 0.1 weight % and up to and including 30 weight %, or more likely of at least 1 weight % and up to and including 10 weight %, or even at least 1 weight % and up to and including 8 weight %, based on the total weight of the aqueous pigment-based ink.
• Each aqueous pigment-based ink generally comprises one or more humectants that are generally water soluble or water miscible organic solvents having a viscosity that is greater than 40 centipoise (0.040 mPa-sec) or even at least 100 centipoise (0.1 mPa-sec) when measured at 25°C.
• any water-soluble humectant known in the inkjet art that is compatible with the other requirements of the invention can be used. While an individual humectant can be employed, mixtures of two or more humectants, each of which imparts a useful property, can be used. Representative humectants are described for example, in U.S. Patent 9,783,553 (Lussier et al.).
• the one or more humectants such as triethylene glycol
• Each aqueous pigment-based ink useful according to the present invention can further comprise one or more anionic polyurethanes, each having an acid number of at least 50, or of at least 60 and up to and including 150, or even at least 55 and up to and including 90, which materials are described in more detail below.
• the aqueous pigment-based ink can comprise one or more anionic (meth)acrylic or anionic styrene-(meth)acrylic polymers, each having an acid number of at least 50, or of at least 120 and up to and including 240, or even at least 160 and up to and including 220, which polymers are described in more detail below.
• the term (meth)acrylic refers to both acrylic materials and methacrylic materials. Representative examples of both types of polymers are described for example in U.S. Patents 8,430,492 (Falkner et al.) and 9,783,553 (noted above).
• particularly useful polyether polyurethanes are individually represented by Structure (I) in U.S. Patent 9,783,553 (noted above).
• Useful water-soluble or water-dispersible anionic poly ether polyurethanes can be prepared as described for example in [0045] - [0049] of U.S. Patent Application Publication 2008/0207811 (Brust et al.).
• the acidic groups in the anionic poly ether polyurethanes can be at least partially and up to 100% neutralized (converted into salts) using monovalent inorganic bases such as alkaline metal hydroxides or organic amines such as dimethylethanolamine.
• anionic (meth)acrylic polymers and anionic styrene- (meth)acrylic polymers useful in the present invention are described for example in [0061] of U.S. Patent Application Publication 2008/207811 (noted above).
• useful anionic styrene-acrylic polymers include those commercially available under the trademarks JONCRYL® (S.C. Johnson Co.), TRUDOT® (Mead Westvaco Co.), and VANCRYL® (Air Products and Chemicals, Co.).
• modified polysiloxanes can be present in the aqueous pigment-based ink(s).
• ethoxylated or propoxylated silicone-based “surfactants” that can be obtained commercially under the trademarks SILWET® (CL Witco), and BYK® (Byk Chemie) such as BYK® 348 and 381, as well as Dow Coming DC67, DC57, DC28, DC500W, and DC51.
• Non-silicone surfactants can also be used, including but not limited to anionic, cationic, nonionic, or amphoteric surfactants such as those commercially available as SURFYNOL® surfactants (Air Products) including SURFYNOL® 440 and 465 alkynediol surfactants.
• anionic, cationic, nonionic, or amphoteric surfactants such as those commercially available as SURFYNOL® surfactants (Air Products) including SURFYNOL® 440 and 465 alkynediol surfactants.
• Colorless fluorescent colorants can also be present in the aqueous pigment-based ink and examples of such compounds are described in U.S. Patent Application Publication 2014/231674 (Cook).
• additives that can be present in the aqueous pigment-based inks, in amounts that would be readily apparent to one skilled in the art, include but are not limited to, co-solvents, thickeners, conductivity -enhancing agents, drying agents, waterfast agents, viscosity modifiers, pH buffers, preservatives, antifoamants, wetting agents, corrosion inhibitors, biocides, fungicides, defoamers (such as SURFYNOL® DF110L, PC, MD-20, and DF-70), UV radiation absorbers, antioxidants, and light stabilizers available under the trademarks TINUVIN® (Ciba) and IRGANOX® (Ciba), as well as other additives described in Col. 17 (lines 11-36) of U.S. Patent 8,455,570 (noted above).
• co-solvents such as SURFYNOL® DF110L, PC, MD-20, and DF-70
• UV radiation absorbers such as SURFYNOL®
• Water is generally present in each aqueous pigment-based ink in an amount of at least 75 weight % or at least 80 weight %, and generally at no more than 90 weight %, based on the total weight of the aqueous pigment-based ink.
• each aqueous pigment-based ink can be adjusted if desired to at least 8 and up to and including 12, or more likely of at least 8 and up to and including 10, or in some embodiments of at least 8 and up to and including 9.5.
• aqueous pigment-based inks useful according to the present invention can be supplied individually or as components of ink sets that can be designed for use in the same inkjet printing apparatus.
• Inkjet-printed articles prepared according to the present invention comprise a substrate (as described above) on which a topcoat composition has been disposed (as described above), and on which at least one aqueous-based inkjet-printed image or layer has been disposed by inkjet printing.
• a substrate as described above
• at least one aqueous-based inkjet-printed image or layer has been disposed by inkjet printing.
• such inkjet-printed image or layer can be monochrome (single color) or multi-color, or even colorless, or a colorless image or layer can be formed over a monochrome or multi-color inkj et-printed image.
• inkjet-printed article 30 can comprise substrate 300 that is composed of water- impermeable support 310 and optional first layer 320 disposed thereon (which can have a water-based tie-layer composition); topcoat composition 330 disposed on first layer 320; aqueous-based inkjet-printed image or layer 340 disposed on topcoat composition 330, and post-print functional layer 350 disposed on aqueous-based inkjet-printed image or layer 340, which post-print functional layer 350 can be a transparent protective layer or an adhesive layer that optionally can have a protective layer adhered thereto.
• postprint functional layer 350 can be a removable scratch-off layer.
• Some methods of the present invention can include, after B) inkjet printing one or more aqueous pigment-based inks on the topcoat composition:
• the resulting inkjet-printed article according to this invention can have a topcoat composition disposed as a pattern or layer on the substrate surface, and a pigment-based inkjet-printed pattern (or image) that can be arranged in registration with the pattern or layer of the topcoat composition.
• a aqueous-based colorless ink composition can be disposed as a pattern in registration with the pigment-based inkjet-printed pattern or image in this particular inkjet-printed article.
• a transparent protective layer can be used as a post-print functional layer to protect the inkjet-printed article against environmental and physical damage and stress, provide abrasion resistance, resistance to fingerprints, and delamination resistance.
• Such transparent protective layers can be provided as described in U.S. Patent Application Publication 2018/0051184 (noted above).
• known aqueous-based overprint varnishes such as Haut Brilliant 17- 604327-7 (Siegwerk) and Micheal Huber Munchen 877801 Varnish Anticurling can be applied as a transparent post-print functional layer.
• An adhesive layer can be present as a post-print functional layer to provide adhesion especially in applications such as flexible laminated packaging wherein it is desired to bond a separate film or paper layer to a treated, coated, or printed layer.
• aqueous-based adhesives useful for such adhesive layers include but are not limited to, Dow Chemical ROBONDTM acrylic adhesives L90M, L0148, and L330 that can be used in combination with a crosslinking agent such as Dow Chemical CR 9-101.
• Another option is the Dow Chemical AQUALAMTM polyurethane aqueous-based adhesive used in combination with the Dow Chemical CR 7-103 crosslinking agent.
• post-print functional layer 350 when post-print functional layer 350 is present and is aqueous-based, it can be applied or formed using any of the methods described above for applying or forming first layer 320 and topcoat composition 330, including known coating and digital deposition processes.
• post-print functional layer 350 can be applied as a flood coating across the entire surface of the treated, coated, and inkjet-printed article, or it can be applied in a pattern-wise or image-wise fashion.
• post-print functional layer 350 is solvent- free, it can be applied using a melt extrusion process wherein the molten or viscous solventless composition is extruded as a continuous layer over the surface of the dried aqueous-based inkjet-printed image or layer 340.
• post-print functional layer 350 can be further processed using heat and pressure to improve adhesion, followed by cooling.
• a solventless composition can be a two-part reactive composition intended to serve as an adhesive to which a continuous protective post-print functional layer is laminated using heat or pressure.
• the inkjet-printed article according to the present invention is simpler in structure (not shown) compared to that illustrated in FIG. 3.
• an aqueous-based inkjet-printed image or layer like 340 is disposed directly on a topcoat composition.
• first layer 320 is omitted.
• Post-print functional layer 350 can be present or omitted from such embodiments.
• An aqueous composition for pre-treating a substrate prior to inkjet printing thereon having at least 2% solids and up to and including 90% solids, and the aqueous composition comprises the following (a), (b), and (c) components: (a) one or more water-soluble salts of a multivalent metal cation, which (a) one or more water-soluble salts are present in an amount of at least 0.5 weight % and up to and including 30 weight %;
• one or more nonionic or cationic water-soluble or water- dispersible polymeric binder materials are present in an amount of at least 0.1 weight % and up to and including 30 weight %;
• crosslinkable polymeric material that is different from all of the (a), (b), (c), and (d) components, and which (e) crosslinkable polymeric material is present in an amount of at least 0.1 weight % and up to and including 30 weight %, based on the total weight of the aqueous composition.
• crosslinkable polymeric material is present in an amount of at least 0.1 weight % and up to and including 30 weight %, based on the total weight of the aqueous composition.
• a dispersing aid for the (c) surface-treated visible lightscattering particles which (f) dispersing aid is cationic in cumulative charge and is present in an amount of at least 0.2 weight % and up to and including 50 weight %, based on the total weight of the (c) surface-treated visible light-scattering particles.
• aqueous composition of any of embodiments 1 to 7, wherein the (b) one or more nonionic or cationic water-soluble or water- dispersible polymeric binder materials comprise one or more of a polyvinyl alcohol, polyethylene imine, polyethylene oxide, polyvinyl amine, a copolymer derived at least in part from vinyl alcohol and ethylene oxide, a copolymer derived at least in part from a vinyl amine and vinyl alcohol, or a combination of two or more of these polymeric materials.
• aqueous composition of any of embodiments 1 to 8, wherein the (b) one or more nonionic or cationic water-soluble or water- dispersible polymeric binder materials comprise at least a polyvinyl amine, polyethylene imine, a polyvinyl alcohol, a copolymer derived at least in part from vinyl amine and vinyl alcohol, or a combination of two or more of these polymeric materials.
• the aqueous composition of any of embodiments 1 to 10 having a dynamic viscosity of less than 2000 centipoise (2000 mPa-sec) at 25°C as measured using a Brookfield spindle viscometer.
• aqueous composition of any of embodiments 1 to 14, wherein the (c) surface-treated visible light-scattering particles comprise silicon dioxide, zinc oxide, titanium dioxide, zirconium oxide, aluminum oxide, barium sulfate, magnesium oxide, or a combination of two or more of these materials.
• aqueous composition of any of embodiments 1 to 16 comprising an aqueous medium composed of at least 50 weight % water, based on the total weight of all solvents in the aqueous medium.
• a aqueous composition providing one or more embodiments of the present invention for pre-treating a substrate prior to inkjet printing thereon, the aqueous composition having at least 5% solids and up to and including 70% solids, and a dynamic viscosity of at least 30 centipoise (30 mPa- sec) and up to and including 800 centipoise (800 mPa-sec) as measured at 25°C using a Brookfield spindle viscometer, and the aqueous composition comprises the following (a), (b), (c), (d), (e), and (1) components:
• visible light-scattering particles comprising visible light scattering titanium dioxide particles, that have been surface-treated such that the aqueous composition has a stable zeta potential of greater than +10 millivolts, wherein the surface-treated visible light-scattering titanium dioxide particles exhibit a Dso (median) particle size of at least 0.04 pm and up to and including 2 pm, as measured using a particle size analyzer that provides a volume-weighted particle size distribution, and which surface-treated visible light-scattering particles are present in an amount of at least 10 weight % and up to and including 40 weight %, based on the total weight of the aqueous composition;
• crosslinkable polymeric material that is different from all of the (a), (b), (c), and (d) components, and which (e) crosslinkable polymeric material is present in an amount of at least 0.2 weight % and up to and including 8 weight %, based on the total weight of the aqueous composition;
• a dispersing aid for the (c) surface-treated visible lightscattering titanium dioxide particles which (f) dispersing aid is a polymer having a protonated nitrogen atom, and is present in an amount of at least 0.2 weight % and up to and including 50 weight %, based on the total weight of the (c) surface- treated visible light-scattering titanium dioxide particles. 19.
• the (1) dispersing aid is at least a protonated polyethylene imine or protonated polyvinyl amine.
• aqueous composition of any of embodiments 18 to 20, comprising an aqueous medium composed of at least 50 weight % water, based on the total weight of all solvents in the aqueous medium.
• An inkjet receiving medium comprising a substrate and a topcoat composition disposed on a surface thereof, which topcoat composition is derived from the aqueous composition of any of embodiments 1 to 21, and comprises the following (a), (b), and (c) components:
• topcoat composition has a dry solids coating weight of at least 0.2 g/m 2 and up to and including 1 g/m 2 .
• the substrate is a transparent, translucent, or metallized polymeric film.
• the topcoat composition has an opacity of at least 30% and a colorimetry defined by an a* value of at least -5 and up to and including +5 and a b* value of at least -5 and up to and including +5.
• topcoat composition is disposed on the substrate surface as a continuously distributed layer.
• the substrate comprises a hydrophobic surface prior to the topcoat composition being disposed thereon, which hydrophobic surface is impermeable to water or to an aqueous pigment-based ink composition, and which topcoat composition provides a hydrophilic surface relative to the hydrophobic surface of the substrate.
• the water-impermeable support comprises a transparent or translucent polymeric film, or a co-extrudate or a laminate of two or more transparent, translucent, or metallized polymeric films.
• topcoat composition further comprises the (d) particles different from the (c) component, in an amount of at least 0.06 weight % and up to and including 10 weight %, based on the total weight of the topcoat composition.
• the topcoat composition further comprises the (e) a crosslinkable polymeric material that is different from all of the (a), (b), and (c) components, present in an amount of at least 0.1 weight % and up to and including 30 weight %, based on the total weight of the topcoat composition.
• a dispersing aid for the (c) visible light-scattering particles which (f) dispersing aid is present in an amount of at least 0.2 weight % and up to and including 50 weight %, based on the total weight of the (c) surface- treated visible light-scattering particles.
• the substrate surface has a static surface energy that is greater than 45 dynes/cm prior to disposition of the topcoat composition.
• the (f) dispersing aid comprises at least a protonated polyethylene imine or protonated polyvinyl amine.
• any embodiments of the present invention including embodiments 40 to 44 noted above, wherein the substrate comprises a transparent, translucent, or metallized polymeric film, and the method comprising disposing the aqueous composition so that the resulting topcoat composition has a dry solids coating weight of at least 0.2 g/m 2 and up to and including 2 g/m 2 , and the aqueous composition comprises the following (a), (b), (c), (d), (e), and (1) components:
• visible light-scattering particles comprising visible lightscattering titanium dioxide particles that have been surface-treated such that the aqueous composition has a stable zeta potential of greater than +10 millivolts, wherein the surface-treated visible light-scattering titanium dioxide particles exhibit a D50 (median) particle size of at least 0.04 pm and up to and including 2 pm, as measured using a particle size analyzer that provides a volume-weighted particle size distribution, and which surface-treated visible light-scattering titanium dioxide particles are present in an amount of at least 10 weight % and up to and including 40 weight %, based on the total weight of the aqueous composition;
• crosslinkable polymeric material that is different from all of the (a), (b), (c), and (d) components, and which (e) crosslinkable polymeric material is present in an amount of at least 0.2 weight % and up to and including 8 weight %, based on the total weight of the aqueous composition;
• a dispersing aid for the (c) surface-treated visible lightscattering titanium dioxide particles which (f) dispersing aid is a polymer having a protonated nitrogen atom, and is present in an amount of at least 0.2 weight % and up to and including 50 weight %, based on the total weight of the (c) surface- treated visible light-scattering titanium dioxide particles.
• a method for inkjet printing comprising, in order:
• the one or more aqueous pigment-based inks comprise one or more pigment colorants selected from a cyan pigment, a magenta pigment, a yellow pigment, a black pigment, a green pigment, an orange pigment, a white pigment, a red pigment, a blue pigment, a violet pigment, or a combination of any of these pigment colorants.
• aqueous pigment-based inks independently comprise an anionic polyurethane, a humectant, an anionic (meth)acrylic polymer, an anionic styrene- (meth)acrylic polymer, or any combination of these materials.
• any of embodiments 47 to 50 comprising printing one or more aqueous pigment-based inks onto the topcoat composition that is disposed on the substrate surface as a pattern, to provide a pigment-based image in registration with the pattern of the topcoat composition using an inkjet deposition system.
• each of the one or more aqueous pigment-based inks is supplied from respective main fluid supplies as one or more continuous streams, each of which one or more continuous stream is broken into both printing drops and non-printing drops; and collecting and returning the non-printing drops from each of the one or more continuous streams to respective main fluid supplies.
• each of the one or more aqueous pigment-based inks has a viscosity of less than or equal to 5 centipoise (5 mPa-sec) as measured at 25°C using a rolling ball viscometer.
• a method for providing an inkjet-printed article comprising, in order:
• A providing an inkjet receiving medium by disposing the aqueous composition of any of embodiments 1 to 20 onto the surface of the substrate to form a topcoat composition
• An inkjet-printed article comprising: a substrate comprising a surface; a topcoat composition disposed on the substrate surface, the topcoat composition derived from the aqueous composition of any of embodiments 1 to 20, and the topcoat composition comprising the following (a), (b), and (c) components:
• the zeta potentials of the aqueous composition were measured using the Malvern Zetasizer Nano-ZS (ZEN) apparatus and electrophoretic mobility of the tested particles. Samples of aqueous compositions were analyzed in an undiluted state. Zeta potential is measured using a combination of the measurement techniques: Electrophoresis and Laser Doppler Velocimetry, sometimes called Laser Doppler Electrophoresis. This method measures how fast a particle moves in a liquid when an electrical field is applied, that is, its velocity.
• Particle size distributions were also obtained using a Horiba LA- 920 apparatus using a static light technique that produced a volume-weighted particle size distribution.
• each sample of particles was diluted with ultrapure water to yield an appropriate amount of light scatter within the limits displayed by the instrument indictors.
• Each sample was analyzed with low level sonication within the instrument to minimize any aggregation that might exist. Results are typically reported as a mean or median particle size wherein particle size is defined in terms of an equivalent spherical diameter (or ESD).
• TiCh dispersions Forty weight % titanium dioxide (TiCh) dispersions were prepared in water using a variety of (b) nonionic or cationic water-soluble or water- dispersible polymeric binder materials as dispersants (hereinbelow, “polymer”). To a glass vessel, each polymer was added at the level indicated in the following TABLE I to water and stirred until dissolved. The temperature of the resulting solution was raised if the dissolution rate was too slow. To each polymer solution, Chemours R-960 TiCh visible light-scattering particles in powder form were added slowly until the powder was wetted out, to provide the necessary (c) surface-treated visible light-scattering particles.
• polymer nonionic or cationic water-soluble or water- dispersible polymeric binder materials as dispersants
• the resulting dispersion was then stirred with a high rpm colloid mill for 1 hour.
• the compatibility with a (a) water- soluble salt of a multivalent metal cation (“salt”) was tested by adding 2 weight % magnesium chloride (MgCh) to the mixture followed by stirring.
• MgCh magnesium chloride
• the results shown below in TABLE I indicate just a single (b) nonionic or cationic water- soluble or water-dispersible polymeric binder material tested, Lupamin® 9095, provided a stable dispersion that was tolerant to salt (“pass”).
• the titanium dioxide particles that precipitated in the dispersions failed the salt test.
• PVP refers to polyvinyl pyrrolidone
• Example 2 Aqueous coating solutions (250 g) were prepared utilizing an inventive polymer and a TiCh containing dispersion as shown above in TABLE I. To 72.5 g of water was added 29.6 g of Lupamin® 9095 (b) binder material. To this, 0.4 g of Carbowet® 106 surfactant (available for example from Evonik Corporation) was added, then 125.0 g of Chemours R-960 visible light-scattering titanium dioxide particles, after which the dispersion was stirred with a homogenizer at high rpm for 1 hour.
• Carbowet® 106 surfactant available for example from Evonik Corporation
• Sample 2.02-1 was made identically to Sample 2.01-1 except that 10.0 g of Poly cupTM 9700 crosslinker (available for example, from Solenis Specialty Chemicals) was added prior to coating each polyester substrate.
• a commercial Sun Chemical DPQ-173 white composition available from Sun Chemical was used to coat the transparent polyester substrate to form Sample 2.03-C. All of these samples were provided with the same aqueous coating wet laydowns.
• the opacity (determined using the TAPPI opacity test described above) was measured on each resulting inkjet receiving medium.
• the three coatings were printed with a standard separation test pattern using a commercial Kodak Stream Continuous Inkjet printer loaded with aqueous cyan, magenta, yellow, and black pigment-based inks (commercially available KODAK PROSPER® Press QD Packaging Inks), all of which contained anionically- stabilized colored pigments.
• Dmax maximum optical density achieved for the 3 CMY primary colors and black K aqueous pigment-based inks are shown below in TABLE II.
• the two Inventive samples (2.01-1 and 2.02-1) exhibited superior opacity to the Comparative sample 2.03-C prepared from the commercial fluid and inkjet-printed with high optical density.
• the Comparative sample also failed in inkjet printing due to excessive ink coalescence caused by lateral ink spread resulting in adjacent ink drops merging before the water has evaporated from the applied ink.
• the noted Comparative Example coating did not contain a (a) water-soluble salt having a multivalent cation as required in the present invention and this omission led to unacceptable inkjet-printed images.
• the Sun Chemical DPQ-173 white precoat composition noted above was evaluated for compatibility with a water-soluble salt having a multivalent metal cation.
• To 100.0 g of Sun Chemical DPQ-173 white precoat composition was added 2.0 g of MgCh.6H2O salt to form Comparative sample 3.01-C. It was observed that the white pigment in the resulting dispersion precipitated, making the aqueous composition containing the water-soluble salt impossible to coat.
• a concentrated pigment dispersion of (c) visible lightscattering particles was prepared by weighing 102.9 g of water into a 500 g glass vessel. To this was added 57.1 g of Lupamin® 9095 (b) binder material with mixing until the polymer was fully incorporated. Then, 240 g of Chemours R-960 titanium dioxide particles was added slowly and mixed under high shear with a colloid mill. Each resulting dispersion contained 60 weight % of the (c) surface- treated visible light-scattering titanium dioxide particles.
• Aqueous compositions according to the present invention were prepared using the pigment dispersion as described below in TABLE III. The noted components were added in gram quantity and in the order as indicated and stirred after each addition.
• the SelvolTM 103 polyvinyl alcohol (available for example from Sekisui Specialty Chemicals) was delivered as a 20 weight % gel solution and the NBK-020322-07E polyurethane polymer manufactured by DCM was delivered as a 40 weight % latex dispersion.
• TABLE III Aqueous Compositions for Example 4
• a Comparative precoat composition 4.07-C was prepared similarly to the aqueous compositions described in TABLE III but with the primary difference that no pigment dispersion containing visible light-scattering particles was included.
• This example set shows that the dispersion process used in the preceding examples can be applied to other pigments that are (c) visible lightscattering particles of various particle sizes.
• These dispersions were formulated in the same way as described above in Example 4 except that the dispersions contained 50 weight % of visible light-scattering particles (pigment particles) and the Lupamin® 9095 polyvinyl amine (b) binder material level was set to 5 weight % of the (c) visible light-scattering particle solids.
• the resulting dispersions were sized using the Horiba particle size analyzer noted above, and all of them passed the “salt” test (described above in Example 1). These dispersions are described in the following TABLE V. TABLE V: Results for Example 5
• PVA refers to polyvinyl alcohol
• aqueous compositions formulated and used in this example were like those described in Example 6 except that the pigment dispersion containing (c) visible light-scattering titanium dioxide particles was created using an alternative (b) nonionic or cationic water-soluble or water-dispersible polymeric binder material, Lupasol® FG polyethylene imine (b) binder material, that was first added to water and the pH was adjusted to 7.0 with 5 molar HC1. Then, powdered Chemours R-900 surface-treated titanium dioxide was slowly added. The resulting mixture was stirred with a homogenizer at high rpm for 1 hour.
• Carbowet® 106 surfactant was added and followed by dry SelvolTM 103 polyvinyl alcohol prior to a heat ramp to 90°C and held for 1 hour. After cooling to 40°C, Lupamin® 9095 polyvinyl amine (b) binder material, MgCh, and Poly cupTM 9700 crosslinker were added with 10 minutes of stirring in between each step. Each resulting aqueous composition was coated onto a poly(ethylene terephthalate) substrate using a reverse gravure coating cylinder at a wet laydown of 4.0 g/m 2 to form an inkjet receiving medium.
• the Lupasol® FG polyethylene imine and Lupamin® 9095 polyvinyl amine materials were varied in two formulas as indicated below in TABLE VIII.
• each resulting inkjet receiving medium was analyzed for the opacity (determined using the TAPPI opacity test described above) and printed with a continuous inkjet printer as described above.
• the Comparative Sample shown in TABLE VIII was prepared identically to Comparative Sample 6.08-C. High opacity and excellent printing results were obtained for the two Inventive samples 7.01-1 and 7.02-1 but the Comparative sample 7.03-C exhibited low opacity due to the absence of (c) surface-treated visible light-scattering particles in the topcoat composition under the inkjet- printed image.
• Example 8 This example shows the efficacy of using a white pigment
• the noted aqueous compositions were analyzed for zeta potential prior to coating onto a substrate.
• the Comparative sample 8.08-C had no visible- light-scattering particles and so zeta potential was not applicable.
• All the Inventive samples 8.01-1 through 8.07-1 displayed a positive zeta potential that rendered the aqueous compositions stable in the presence of the (a) water-soluble magnesium chloride salt.
• Each of the aqueous compositions was coated onto a poly(ethylene terephthalate) support using a reverse gravure coating cylinder at a wet laydown of 4.0 g/m 2 .
• the Chemours R-900 (c) surface-treated visible lightscattering titanium dioxide particles and KaMin Polygloss® 90 particles were varied in the formulations as indicated in the following TABLE X. Each coating was analyzed for opacity (using the TAPPI opacity test described above) and printed with a continuous inkjet printer. The results for each of the Inventive aqueous compositions containing the (c) surface-treated visible light-scattering particles indicate the efficacy of combining one or more of these types of such particles to achieve a desired opacity and cost while maintaining excellent print quality as part of a continuous inkjet system. However, the Comparative aqueous composition 8.08-C exhibited low opacity due to the absence of (c) surface-treated visible light-scattering particles in the inkjet-printed surface of the inkjet receiving medium.
• This example shows the zeta potential measurement to be predictive for when a pigment dispersion containing (c) surface-treated visible light-scattering particles will be stable in the presence of a (a) water-soluble salt like magnesium chloride.
• Each dispersion was prepared by dissolving a (b) nonionic or cationic water-soluble or water-dispersible polymeric binder material in water, adding the dry pigment containing (c) surface-treated visible lightscattering particles, and then mixing the dispersion with a homogenizer at high rpm for 1 hour. In all cases, the pigment concentration was 5 weight %.
• the first four dispersions contained no (I) dispersing aid, and the first three dispersion contained a buffer solution rather than water.
• the (I) dispersing aid level shown below in TABLE XI is given as a weight % of the pigment loading.
• the stability to the (a) water-soluble salt was determined by adding 2 weight % of MgCh to the dispersion after it was made.
• the Inventive dispersions that remained stable are listed as “pass” while the Comparative dispersions from which the (c) surface- treated visible light-scattering particles precipitated are listed as “fail”.
• Example 11 shows the utility of a (b) nonionic or cationic water- soluble or water-dispersible polymeric binder material according to the invention to stabilize a greater variety of pigments containing visible light-scattering particles suitable for aqueous compositions and topcoat compositions according to the present invention.
• Each dispersion sample was prepared using a Sigma- Aldrich low MW polyethylene imine (1) dispersing aid to shift the ionic charge in the pigment dispersions.
• Each aqueous dispersion (100 g) was prepared so it each contained 10 weight % of pigment containing (c) visible light-scattering particles.
• Each candidate pigment was tested with and without (1) dispersing aid added to each dispersion.
• the dispersions that contained the (b) binder material were adjusted to a nominal pH of 6 using 1 molar hydrochloric acid. All dispersions were stirred using a homogenizer at high rpm for 1 hour. Particle size and zeta potential were measured in the resulting aqueous compositions containing the (a) water-soluble salt to explain the results of the MgCh salt test described earlier.
• This example shows the ability of a (b) nonionic or cationic water- soluble or water-dispersible polymeric binder material according to the invention to stabilize the Chemours R-960 surface-treated visible light-scattering titanium dioxide particles over a range of pH conditions.
• Each dispersion (100 g) was prepared so it contained 5 weight % pigment and a (b) binder material level that was 10 % of the pigment solids.
• the dispersion formulas were adjusted for pH after the (b) binder material had been dissolved in distilled water. The pH adjustments were made using 1 % percent hydrochloric acid and 0.5 molar sodium hydroxide.
• PEI polyethylene imine
• Example 13 This example evaluated the ability of a range of different (b) binder materials to act as (I) dispersing aids and to stabilize the Chemours R-960 pigment containing (c) visible light-scattering particles according to the present invention.
• Each dispersion (100 g) was prepared so that it contained 5 weight % pigment and a (b) binder material level that was 10 weight % of the pigment solids.
• Each dispersion formula was adjusted to a pH of 7 after the (b) binder material had been dissolved in distilled water, using 1 weight % hydrochloric acid or 0.5 molar sodium hydroxide depending upon which direction the solution needed to go to achieve a final pH of 7.
• each dispersion was stirred using a homogenizer at high rpm for 1 hour. Zeta potential, Horiba particle sizing, and the 2 weight % MgCh salt test were conducted on each final aqueous composition. The results are shown below in TABLE XV. In all samples without exception, the (b) binder materials capable of achieving charge reversal and a positive zeta potential were compatible with the (a) water-soluble salt. In addition, the positively charged pigment particle dispersions were on average smaller than the negatively-charged pigment particle dispersions.
• the SelvolTM polymers are available from Sekisui Specialty Chemicals
• This example evaluated the ability of Lupasol® P and Lupasol® FG polymeric materials to produce three different pigment dispersions containing (c) surface-treated visible light-scattering titanium dioxide particles.
• Each dispersion (100 g) was prepared so that it contained 30 weight % of TiCh particles and a (b) binder material level that was either 5 weight % or 15 weight % of the TiCh solids.
• Each dispersion formula was adjusted to a pH of 7 after the noted (b) binder material had been dissolved in distilled water, using 5 molar hydrochloric acid. After adding the TiCh particles to each pH adjusted polymer solution, the resulting dispersions was stirred with a homogenizer at high rpm for 1 hour.
• aqueous compositions formulated and used in this example were like those described above in Example 7.
• Lupasol® P (13.5 g) containing (b) a nonionic or cationic water-soluble or water-dispersible polymeric binder material was first added to 74.5 g of water and the pH of the resulting (b) binder material solution was adjusted to 7.0 with 5 molar HC1. Then, 45.0 g of powdered Chemours R900 titanium dioxide particles was slowly added to each (b) binder material solution to produce a dispersion of (c) surface-treated visible-light scattering titanium dioxide particles. The resulting mixture was stirred for 1 hour.
• This example evaluated the ability of SelvolTM Ultiloc 5003 vinyl amine/vinyl alcohol copolymer (available from Sekisui Specialty Chemicals) as a (b) nonionic or cationic water-soluble or water-dispersible polymeric binder material to stabilize a dispersion of (c) surface-treated visible light-scattering titanium dioxide particles.
• Each dispersion (100 g) was prepared so that it contained a (b) binder material level that was a variable weight percent of the TiCh solids. Each dispersion was adjusted to a pH of 7.5 after the (b) binder material had been added to distilled water, using 5 molar hydrochloric acid. The (b) binder material was in dried form and was dissolved during a heat ramp to 90°C and held for 1 hour. After cooling to 40°C, Chemours R-900 titanium dioxide particles was added to each (b) binder material dispersion and mixed with a magnetic stir bar for 1 hour to produce dispersions of (c) surface-treated visible light-scattering titanium dioxide particles.
• Example 17 Use of Aqueous Compositions to Prepare Inkjet Printed Articles:
• BOPET transparent biaxially oriented polyethylene terephthalate
• m-BOPET aluminum metalized BOPET
• Jindal s BICORTM LPX-2 biaxially oriented polypropylene
• Aqueous Compositions :
• aqueous compositions were prepared according to the present invention and used in the following examples to form topcoat compositions onto the various substrates noted above:
• Aqueous Composition 01N-1 is aqueous Composition 01N-1:
• Carbowet® 106 and Lupamin® 9095 were first added to water after which powdered Chemours R960 titania was slowly added as the (c) visible lightscattering particles. The mixture was stirred with a homogenizer at high rpm for 1 hour. Dry SelvolTM 103 was added prior to a heat ramp to 90°C and held for 1 hour with good mixing. After cooling to 40°C, the remainder of the components were added in the order listed with 10 minutes of stirring in between each step.
• Aqueous Composition 08C-1 is aqueous Composition 08C-1:
• Carbowet® 106 was first added to water after which powdered Chemours R900 titania was slowly added as the (c) visible light-scattering particles. The mixture was stirred with a homogenizer at high rpm for 2 hours. Dry SelvolTM Ultiloc 5003 was added and the pH was adjusted to 7.5 with concentrated HC1 prior to adding Lupamin® 9095. This was followed by a heat ramp to 90°C and held for 1 hour with high shear mixing. After cooling to 40°C, the remainder of the components were added in the order listed with 10 minutes of stirring in between each step.
• Aqueous Composition 08C-2B Aqueous Composition 08C-2B:
• Carbowet® 106 and Lupamin® 9095 were first added to water after which powdered Chemours R900 titania was slowly added as the (c) visible lightscattering particles. The mixture was stirred with a homogenizer at high rpm for 2 hours. Dry SelvolTM 103 was added prior to a heat ramp to 90°C and held for 1 hour with high shear mixing. After cooling to 40°C, the remainder of the components were added in the order listed with 10 minutes of stirring in between each step.
• Aqueous Composition 10B-1 is aqueous Composition 10B-1:
• Carbowet® 106 was first added to water after which powdered Chemours R900 titania was slowly added as the (c) visible light-scattering particles. The mixture was stirred with a homogenizer at high rpm for 2 hours. Dry SelvolTM Ultiloc 5003 was added and the pH was adjusted to 7.5 with concentrated HC1 prior to adding Lupamin® 9095. This was followed by a heat ramp to 90°C and held for 1 hour with high shear mixing. After cooling to 40°C, the remainder of the components were added in the order listed with 10 minutes of stirring in between each step.
• a topcoat composition was formed on each of the identified substrates using an appropriate aqueous composition according to the present invention, as are identified above.
• the titanium dioxide level in the resulting topcoat compositions was reduced by 20%.
• each substrate Prior to applying the aqueous composition, each substrate was treated with a corona discharge device when required to provide acceptable wetting at a treatment energy density applied to the bare film surface of about 80 W-min/m 2 .
• the substantially similar aqueous compositions were then applied to the substrates using a roll-fed RK PrintCoat Instruments Ltd. Rotary Koater and either reverse gravure or smooth roller offset gravure coating procedure.
• the reverse gravure coating process delivered 5.0 - 7.5 cm 3 /m 2 wet laydown of aqueous composition.
• the single station gravure desirably used a 60° hex engraving, 250 liter/inch (98.4 liter/cm), 14.8 BCM cylinder (100 line/cm, 23.0 cc/m 2 ).
• the reverse gravure coating transfer efficiency could be varied by changing the ratio of coating roller to web speed ratio; higher speed ratios gave lower wet coverages. The speed ratios varied from ⁇ 1.0 to 1.8.
• the coating was first transferred to a smooth roller that was pressed against the web by a metal backing roller to form a nip with the web.
• the gravure roller, smooth transfer roller, and metal backing roller were all geared together to move at a common speed.
• the offset coating process delivered 5.8 - 6.3 cm 3 /m 2 wet laydown of aqueous composition.
• the coated substrates were dried in-line using hot air dryers that produced a web temperature of at least about 40°C, resulting in a dry topcoat composition coverage range of 1.8-2.6 g/m 2 on inkjet receiving media having opacities ranging from 52% to 56%.
• each of the resulting ink-receptive media was then either inkjet- printed in-line with one or more CIJ imprinting systems, or each was spooled onto cores for later sheet-fed printing using a single-color 1-inch (2.54 cm) printhead on a benchtop apparatus employing pressurized containers for ink delivery, or a full-width, four-color CIJ printing system supplied with pump-pressurized recirculating ink using a fluid (main supply) station.
• the inkjet receiving media were printed with aqueous cyan, magenta, yellow, or black pigment-based inks (commercially available KODAK PROSPER® Press QD Packaging Inks), all of which contained anionically-stabilized colored pigments.
• the ink reservoirs of a roll-fed continuous inkjet printing test stand fixture were charged with aqueous pigmentbased cyan and magenta inks.
• the roll-fed printing test fixture was connected inline, downstream from an RK PrintCoat Instruments Ltd.
• Rotary Koater gravure coating applicator allowing the roll-fed, uncoated flexible transparent or metalized substrate to first be pre-coated with an aqueous composition according to this invention to form a white topcoat composition (or layer) in an inkjet receiving medium as described previously, to be at least partially dried, and then inkjet- printed using one or more in-line KODAK PROSPER® S10 Imprinting Systems employing a full-width (4.25-inch (10.8 cm)) StreamTM 600 nozzle per inch (236 nozzle per cm) continuous inkjet printhead module enabling either 600x600 dot per inch (236x236 dots per cm) addressability, or 600x900 dpi (236x354 dpcm). The corresponding drop volumes at these resolutions were about 9.8 and 11.4 picaliters, respectively.
• the imprinting system consisted of the following elements:
• (1) two fluid system stations capable of (a) pressurizing the aqueous cyan and magenta pigment-based inks in excess of 60 psid (0.41 MPa) thereby producing ink volumetric flow rates of up to about 2 liters/min; (b) delivering pressurized anionically-stabilized aqueous cyan and magenta pigmentbased inks, as indicated in TABLE XX below from continuous inkjet printhead drop generator modules; (c) returning unprinted (or unused) ink under vacuum to their respective fluid system ink reservoirs; (d) detecting the reservoir ink concentrations by electrical resistivity measurement and replenishing the aqueous cyan or magenta pigment-based inks with replenisher fluid if they had been concentrated by water evaporation, and adding more aqueous cyan or magenta pigment-based inks to their respective ink reservoirs instead if it was depleted by use in printing and was at the correct colorant concentrations; and (e) providing the printheads with Printhead Cleaning
• continuous inkjet printhead PIC box assemblies each including (a) a KODAK PROSPER® Press Jetting Module with a MEMS silicon-based drop generator to form printing and non-printing drops of aqueous pigment-based inks and a Coanda gutter to catch non-printing drops when the printer was not printing an image file or when it is not printing a given pixel even if it is printing an image file; (b) a non-printing drop deflection apparatus creating a deflection zone intersecting the drop curtain provided by positive and negative air duct assemblies to direct the non-printing drops to the Coanda gutter, and (c) an ink return line to the fluid system ink reservoir, and
• a print controller that (a) synchronizes the web spatial location in accord with the data feed to the jetting module and also (b) transmits electrical signals to the jetting module CMOS circuitry that renders a raster processed image into pixel by pixel ink stream stimulation instructions using nozzle plate heater pulse patterns by optimized waveforms to generate non-printing catch drops and printing drops of aqueous pigment-based ink delivered at the printing substrate surface pixel locations, as required.
• Each fluid system utilized a Micropump Inc. MICROPUMP® series GJ-N23DB380A gear pump to deliver the ink through a Pall Corp.
• Disposable Filter Assembly capsule filter, DFA4201ZU0045 containing 0.45 pm nominal effective pore size ULTIPOR® GF-HV glass fiber media at about 65 psid (0.45 MPa) pressure drop at the nozzle plate, which generated a uniform drop velocity of about 20 m/sec.
• the fluid system gear pump speed setting was continually adjusted to provide and maintain constant fluid pressure at the jetting module to uniformly produce the desired drop velocity as per the system specification.
• the required system parameter settings for proper jetting and accurate aqueous cyan or magenta pigment-based ink replenishments were determined and recorded to a computer file termed an “inkdex” to enable printing on other systems, such as a web press fitted two-up with production KODAK PROSPER® S10 Imprinting Systems.
• the deflected non-printing ink drops were caught on a Coanda gutter and returned to the fluid system ink tank under vacuum. Sustained operation of the printer in catch mode of the non-printing drops resulted in gradual evaporation of the aqueous ink solvent vehicle.
• Aqueous cyan and magenta pigment-based ink concentrations were maintained to within about 5% of the original aqueous pigment-based ink concentrations by addition of the particle-free Replenisher Fluid to it if the latter became more than about 5% concentrated based on an ink electrical resistivity determination.
• Test targets were raster image processed to produce digital printing signal instructions for each pixel location at the appropriate transport speed of the test substrate at 600x600 pixels per inch (ppi) (236x236 pixels per centimeter (ppcm)).
• test images were printed at different substrate transport speeds -using a 600 nozzles/inch (236 nozzles/cm) PROSPER® Press Jetting Module in a production print-head assembly configuration, which produced a 4.25-inch (10.8 cm) jet curtain print swath.
• inkjet-printed articles were dried in-line using a 0.7 m hot air dryer followed by a high velocity air knife and were wound up in roll form before chopping out segments in sheet form for further testing.
• the drying system produced single color inkjet-printed ink surface temperatures of at least about 43°C and two-color inkjet-printed ink surface temperatures of at least about 40°C. Speeds were typically 40 feet/min (12 meters/min).
• a sample of the inkjet-printed article as described above was evaluated subjected to a finger rub test or ink cohesion tape test.
• the finger rub was carried out using a back and forth rub; and the rub was carried out after adjusting the pressure of the rub on a scale to give about 300 g of load.
• the level of ink movement from a finger rub was rated as good (no ink movement), fair (slight ink movement), or poor (heavy ink movement).
• TABLE XX indicates that good adhesion of the unprinted areas were observed on the clear BOPP and BOPET and metalized PET substrates. Little to no removal of the opaque ink receptive layer was removed using the tape test. Similarly, ink cohesion was good to prevent little or no removal of ink using the tape test. The finger rub tests showed that under some conditions an overprint varnish may be useful to provide an optimal dry rub test. In the column of TABLE XX below that is labeled “Ink (%
• Humectant is an identifier for glycerol
• 1,2-PD is an identifier for 1,2- propanediol
• TAG is an identifier for triethylene glycol
• the fixture consisted of the following elements: (1) a pressure vessel fluid system for each color ink (aqueous cyan, magenta, yellow, and black pigment-based inks as described above) capable of pressurizing the aqueous pigment-based inks in excess of 60 psid (0.41 MPa) thereby producing ink volumetric flow rates through atypical 600-nozzle/inch (236 nozzle/cm) MEMS silicon nozzle plate of about 63 ml/min/inch (24.8 ml/min/cm) of printhead nozzle plate; (2) a fluid manifold delivering pressurized ink to a miniaturized version of a KODAK PROSPER® Press Jetting Module drop generator to form printing and non-printing drops of aqueous pigment-based inks using a 4.16 inch (10.57 cm) nozzle plate; (3) a drop selection system consisting of (a) a gutter to catch nonprinting drops when the printer is not printing an image file or when it is not printing a given pixel even if
• the printing apparatus drum was loaded with a single sheet of inkjet receiving medium according to this invention, having a topcoat composition on a polymeric film substrate that was affixed by its back side to a sheet of paper for convenience in handling.
• the drum was moved under each color module and rotated at 325 ft/min (98.5 m/min), printing in 4-color register.
• the aqueous pigment-based inks used in these tests were commercially available KODAK PROSPER® QD Packaging Inks.
• the printed sheet was removed and allowed to air dry at ambient temperature and humidity overnight, or it was incubated at 60°C in a laboratory oven for about 5 minutes before testing and further processing. This process was used to create color linearization and IT8 color printing targets to develop ICC color profiles for 4-color roll fed printing.
• a color profile was developed for opaque aqueous compositions 01N-1 applied at a dry laydown of 3.4 g/m 2 .
• the opacity of the white topcoat composition on the LPX-2 BOPP was
• the inkjet-printed and varnished articles were dried in-line using 3 x 0.7 m hot air dryers that produced a web temperature of at least about 50°C, resulting in a dry varnish layer coverage range of 2.5-2.9 g/m 2 .
• the gloss of the resulting coating was measured at 60° to be about 18 units.
• topcoat composition 340 aqueous-based inkjet-printed image or layer

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• 2021
  • 2021-10-06 EP EP21801743.2A patent/EP4232296A1/de active Pending
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