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
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
• • 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
  • B41M5/5236—Macromolecular coatings characterised by the use of natural gums, of proteins, e.g. gelatins, or of macromolecular carbohydrates, e.g. cellulose
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
  • B41M2205/34—Both sides of a layer or material are treated, e.g. coated
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
  • B41M2205/36—Backcoats; Back layers
• • 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
  • B41M5/502—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording characterised by structural details, e.g. multilayer materials
  • B41M5/504—Backcoats

Definitions

• the present invention relates to an ink-receptive topcoat for ink jet printing media. More particularly, the invention relates to an ink-receptive topcoat for ink jet printing media, which utilizes a polysaccharide as a binder.
• inkjet printing technology is usually broken down into two categories: continuous flow and drop-on- demand printing (including thermal and piezoelectric systems).
• ink droplets are ejected from a nozzle at high speed in a controlled manner to come in contact with a recording media to produce a printed image on the media surface.
• the ink droplets, or recording liquid are generally comprised of a recording agent, such as a dye or pigment, and a significant amount of a carrier liquid component.
• the carrier liquid is typically water and an organic solvent such as a monohydric alcohol, a polyhydric alcohol or mixtures thereof.
• InkJet recording media is typically composed of a base support layer having on at least one surface thereof an ink-receiving or image-receiving coating.
• InkJet media types include those intended for reflection viewing, which have an opaque support layer such as a paper or pigmented film, and those intended for viewing by transmitted light, which have a transparent film support layer.
• InkJet media are typically used in both Narrow Format and Wide Format ink jet imaging devices or printers. InkJet media is typically used to produce a wide variety of printed materials.
• Narrow Format, or Home/Office printed applications include, but are not limited to, newsletters, reports, brochures, catalog sheets, mailing labels, inventory control documents, tags, invitations, greeting cards etc.
• Wide Format, or business to business (B2B) printed applications include, but are not limited to, maps, billboards, vehicle graphics, banners, posters, and signs.
• an ink jet media topcoat is to effectively absorb the liquid solvent, or carrier component of the ink jet ink, while providing sufficient "hold out” properties which allow the solid pigment or dye component of the ink jet ink to remain concentrated near the coated surface and effectively produce an acceptable quality printed image.
• the topcoat provides a base to which the ink can adhere. Without this coating, the inks would run, flake off or not dry.
• Inkjet media topcoats control dry time of the ink by interacting with the chemistry of the ink. The topcoats also regulate drop spread. That is, the ink drop needs to maintain a certain circumference at its base. Topcoats prevent the ink drop from spreading and flattening.
• the topcoat also controls how far the ink drop is saturated into the media, ensuring that the ink saturates only to a certain point. Without a coating, many media such as paper would experience bleed through. The topcoat prevents ink from saturating these products and soaking through to the opposite side. Importantly, topcoats improve image definition. A smooth coating that controls saturation, bleed-through, spread and height of the drop will result in good image definition and image clarity.
• Topcoat options include swellable, porous, and hybrid topcoats. Porous topcoats are quick drying, provided they are of sufficient thickness and possess sufficient pore volume to effectively contain and control the liquid ink.
• a porous recording media coating can be manufactured containing, a particulate (filler), a binder and a solvent, or carrier.
• Particulate-containing topcoats are applied to a media support layer and subsequently dried bonding them to the media base.
• the particles are often silica, but other materials including calcium carbonate and kaolin are used.
• the solvent or carrier can be either water or an alcohol.
• Typical solvents or carriers include de-ionized water, alcohol (monohydric or polyhydric) or a combination thereof. Choice of the carrier, solvent type and composition can affect the absorption and drying characteristics of the topcoat during application to the base media sheet.
• a polymeric binder that is compatible with the aforementioned components is used to bind the particles to the paper. The binder helps the absorption of the carrier liquid of the ink. The binder material imparts to the base (receiver) sheet improvements in optical density and coating adhesion to the substrate, reduced chalking of the applied topcoat, and greater paper-like texture of the coated base sheet.
• the binder also serves the function of holding the pigment so as to reduce or eliminate dusting or chalking of the ink which results in clogging of the very fine orifice nozzles of ink jet printers.
• the binder can be a hydrophilic polymer such as polyvinyl alcohol, polyvinyl pyrrolidone, gelatin, cellulose ethers, polyoxazolines, polyvinylacetamides, partially hydrolyzed polyvinyl acetate/vinyl alcohol, polyacrylic acid, polyacrylamide, polyalkylene oxide, sulfonated or phosphated polyesters and polystyrenes, casein, zein, albumin, and the like.
• a hydrophilic polymer such as polyvinyl alcohol, polyvinyl pyrrolidone, gelatin, cellulose ethers, polyoxazolines, polyvinylacetamides, partially hydrolyzed polyvinyl acetate/vinyl alcohol, polyacrylic acid, polyacrylamide, polyalkylene oxide, sulfonated or phosphated polyesters and polystyrenes, casein, zein, albumin, and the like.
• U.S. Pat. No. 4,478,910 which is incorporated by reference herein discloses a coating layer comprising a water-soluble polymeric binder and fine silica particles.
• Polyvinyl alcohol or its derivatives is the particularly preferred water-soluble polymeric binder.
• U.S. Pat. No. 4,758,461 incorporated by reference herein, describes a topcoat, which includes a silicon containing type pigment and an aqueous binder.
• the liquid viscosity of the aqueous coating liquid at 30° C is in the range of 60 to 200 cps.
• the aqueous binder is one or more water-soluble polymers such as polyvinyl alcohol, starch, oxidized starch, cationized starch, casein, carboxymethyl cellulose, gelatin, hydroxyethyl cellulose and water-dispersed polymers such as SBR latex, MBR latex, vinyl acetate emulsion.
• Polyvinyl alcohol is the preferred binder.
• the ink jet recording medium uses several sizing agents. However, the sizing agents tend to migrate over time in the recording medium, thereby causing changes in the ink absorptivity of the medium and reducing overall print quality of the recorded medium.
• U.S. Pat. No. 5,270,103 incorporated by reference herein, describes a coating of a pigment and a binder, which includes polyvinyl alcohol, and one or more additional binder materials.
• the pigment is a silica, such as a colloidal hydrogel type amorphous silica.
• Additional binders can be a styrene-butadiene latex, a cationic polyamine, a cationic polyacrylamide, a cationic polyethyleneimine, a styrene- vinyl pyrrolidone copolymer, a styrene-maleic anhydride copolymer, a polyvinyl pyrrolidone, or a vinyl pyrrolidone- vinyl acetate copolymer.
• Carbohydrate polymers such as starches and gums can also be used as binders.
• examples include cellulose derivatives, chitin, chitosan, dextran, pectin, agar-agar, arrowroot, guar, carrageenan, tragacanth, xanthan, as exemplified by U.S. Pat. Nos. 6,610,136, 6,551,695 and 6,495,243, each of which is incorporated by reference in their entirety herein.
• Cornstarch is an inexpensive carbohydrate polymer and is one of the lowest binding strength and binding efficiency coating binders that can be used.
• Previous ink jet media topcoats do not effectively absorb the liquid solvent or carrier component and possess sufficient "hold-out properties" to allow solid pigment or dye to remain concentrated near the coated surface. Ink is often absorbed along the fiber on the media surface resulting in a phenomenon called feathering. Topcoat compositions that possess satisfactory absorbance often produce loss of density and hence, inaccurate color reproducibility in the printer image. A correct balance of the properties is very difficult to achieve especially at higher print resolutions and smaller dot diameters. The result is that in some of the teachings of the prior references, the density, sharpness, and roundness of each dot may still not be sufficient to obtain high quality, high contrast, full color recorded images for ink jet paper.
• topcoats that use silica particles often require an excessive amount of binder for processing the solids to achieve the desired minimal coat weight.
• the suspensions become too viscous to allow pumping and uniform application using conventional coaters such as a blade coater. Attempts to use a lower binder level have resulted in excessive "dusting" in the finished product.
• the present invention is directed to the use of a polysaccharide as the binder component for an ink jet print receptive topcoat and a filler comprised of silica, which composition exhibits improved ink jet printing printability and improved color development.
• compositions and methods for using compositions of media topcoat which includes a filler comprised of silica, a binder comprised of a polysaccharide and a carrier wherein a topcoat derived from the coating composition exhibits a high solids content, low viscosity and when dried is printable with liquid ink jet printing inks.
• the method for making an ink jet printing medium in accordance with the present invention includes the steps of:
• preparing a media topcoat comprising a filler comprised of silica, a solvent or carrier and a binder comprised of a polysaccharide; applying the topcoat to at least one side of a substrate; and drying the topcoat on the substrate to produce the ink jet printing medium.
• Still further embodiments of the invention provide printed products of various substrates using the ink receptive topcoat media.
• Polydextrose as the binder is especially preferred.
• the effectiveness of using poly dextrose as the binder element is based on the 1) function of polydextrose as an effective water-based dye solubilizer and, 2) the pH neutral characteristics of polydextrose acting to minimize dye color shifts resulting in a more pure Chroma value.
• FIG. 1 depicts the linkage distribution of FIBERSOL-2 ® versus polydextrose.
• FIG. 2 depicts the summary of linkage and branching for FIBERSOL-2 ® compared to polydextrose.
• the print-receptive topcoat for ink jet printing media of the present invention comprises a filler comprised of silica, a binder comprised of a polysaccharide and a carrier.
• the print receptive topcoat of the present invention absorbs the liquid component of the ink better than previous media, and provides a quicker ink drying time, while preventing bleeding or diffusion of the ink into the substrate media. Additionally, the topcoat causes the ink pigment to be fixed on the media in the form of well-defined dots of uniform size and shape. Moreover, the topcoat of the present invention features superior color depth. [0036] Applicants have surprisingly discovered that ink receptive coating formulations employing a polysaccharide, as a binder could be produced at high solids levels resulting in relatively low viscosities, enabling a broader range of coating technology methods used in the actual topcoat deposition to an ink jet media substrate.
• the low viscosity facilitates pumping, prevents clogging of the applicator nozzle. Low viscosity facilitates uniform application using conventional coaters such as blade coaters.
• ink jet printing media is used interchangeably with “substrate” and refers to materials upon which the ink and topcoat formulation are applied. Any suitable substrate or media can be employed. Examples of suitable ink jet printing media include paper, card stock, metal, wood, plastic, tape, film, or combinations thereof.
• Topcoat formulations produced with a polysaccharide such as polydextrose and/or an indigestible polysaccharide, or dextrinized oligosaccharide in combination with silica yield better color development over those containing PVP.
• a polysaccharide such as polydextrose and/or an indigestible polysaccharide, or dextrinized oligosaccharide in combination with silica yield better color development over those containing PVP.
• a distinct advantage of using polydextrose and/or an indigestible polysaccharide or dextrinized oligosaccharide or combination thereof in ink jet topcoat formulations is the capability of producing high solids/ low viscosity formulas with improved color development over PVP based formulations. This advantage allows for the application of the topcoat utilizing a broad range of coating application processes and technologies.
• Polysaccharides are defined as sugar polymers with more than 10 residues. Oligosaccharides are defined as sugar polymers with 2-10 residues. It is understood that while the term polysaccharides is used throughout, the term encompasses oligosaccharides as well. Therefore, the term “polysaccharide” is inclusive of oligosaccharides as well. " While theoretically there is no limit to the number of residues for the polysaccharides of the present invention, practical limitations are based on solution properties, e.g. solubility and viscosity. The lower limit of residues of the oligo- and polysaccharides of the present invention is based on solubility and the ability to bind with the paper and not wash off easily or cause blocking.
• Oligosaccharides and polysaccharides as defined herein may be homo- or heterosacchraides.
• Homosaccharides are based essentially upon a single sugar, e.g. glucooligosaccharides or fructooligosaccharides, and may contain a single linkage type such as maltooligosaccharides ( ⁇ -l,4-linkages) or a mixture of linkages, e.g.jisomaltooligosaccharides ( ⁇ -l,4-and ⁇ -l,6-linkages).
• Heterosaccharides contain more than a single sugar residue, e.g., arabinogalacatan (arabinose and galactose).
• the polymers may be linear or branched.
• Suitable oligosaccharides and/or polysaccharides include, but are not limited to, maltooligosaccharides (maltodextrin), isomaltooligosaccharides, cyclodextrins, gentiooligosaccharides, nigerooligosaccharides, fructooligosaccharides, inulin, galactooligosaccharides, xylooligosaccharides, agarooligosaccharides, mannooligosacchradies, chitin/chitosan oligosaccharides, arbinogalactan and pullulan.
• maltooligosaccharides maltodextrin
• isomaltooligosaccharides cyclodextrins
• gentiooligosaccharides gentiooligosaccharides
• nigerooligosaccharides fructooligosaccharides
• inulin galact
• polydextrose includes polymer products of glucose which are prepared from glucose, maltose, oligomers of glucose or hydrolyzates of starch, which are polymerized by heat treatment in a polycondensation reaction in the presence of an acid e.g. Lewis acid, inorganic or organic acid, including monocarboxylic acid, dicarboxylic acid and polycarboxylic acid, such as, but not limited to the products prepared by the processes described in U.S. Pat. Nos.
• an acid e.g. Lewis acid, inorganic or organic acid, including monocarboxylic acid, dicarboxylic acid and polycarboxylic acid, such as, but not limited to the products prepared by the processes described in U.S. Pat. Nos.
• polydextrose also includes those polymer products of glucose prepared by the polycondensation of glucose, maltose, oligomers of glucose or starch hydrolyzates described hereinabove in the presence of a sugar alcohol, e.g. polyol, such as in the reactions described in U.S. Pat. No. 3,766,165, which is incorporated by reference herein.
• polydextrose includes the glucose polymers, which have been purified by techniques described in the art, including any and all of the following but not limited to:
• polydextrose includes hydrogenated polydextrose, which, as used herein, includes hydrogenated or reduced polyglucose products prepared by techniques known to one of ordinary skill in the art. Some of the techniques for preparation are described in U.S. Pat. Nos. 5,601,863, 5,620,871 and 5,424,418, all of which are incorporated by reference herein.
• polydextrose also encompasses fractionated polydextrose that is a conventional, known material and can be produced, for example, by the processes disclosed in U.S. Pat. Nos. 5,424,418 and 4,948,596, which are incorporated by reference herein.
• Polydextrose is commercially available from a variety of companies including Danisco Sweeteners, A. E. Staley and Shin Dong Bang (Korea). Purified forms of polydextrose are marketed by Danisco Sweeteners under the name LITESSE ® or
• polydextrose is called LITESSE ULTRA ® .
• the polysaccharide binder of the invention is an indigestible polysaccharide.
• a preferred example of an indigestible polysaccharide is indigestible dextrin(s).
• Indigestible dextrin is a highly branched polysaccharide derived by pyroconversion from starch.
• Starch is made of glucose molecules attached by ⁇ -(l,4) bonds, with, some branching by means of ⁇ -(l,6) bonds. The degree of branching is dependent on the source of the starch.
• the indigestible dextrin is produced from starch in a heat treatment process known as pyroconversion.
• Pyrodextrins are starch hydrolysis products obtained in a dry roasting process either using starch alone or with trace levels of acid catalyst.
• the first product formed in this reaction is soluble starch, which in turn hydrolyzes further to form dextrins.
• the molecular weight of the final product depends on the temperature and duration of heating.
• Transglucosidation can occur in the dextrinization process, in which rupture of an ⁇ -(l,4) glucosidic bond is immediately followed by combination of the resultant fragments with neighboring hydroxyl groups to produce new linkages and branched structures. Thus, a portion of the glycosidic bonds are scrambled.
• a commercially available pyroconverted starch is called FIBERSOL-2 ® and is available from Matsutani America, Inc.
• Another preferred polysaccharide includes the indigestible polysaccharide described in U.S. Patent No. 5,620,871, the contents of which are incorporated by reference.
• U.S. Patent No. 5,620,871 discloses a method for preparing indigestible polysaccharides by carrying out an enzymatic hydrolysis of a dextrin or polysaccharide using at least one saccharifying enzyme and at least one enzyme which hydrolyzes the 1-6 bonds of amylopectin.
• Another preferred example of polysaccharide used as a binder in the present application is described in JP Patent Publication No. 2001/086946, the contents of which are incorporated by reference. It describes a hydrogenated starch hydrolysate containing non-digestible polysaccharides which are obtained by hydrolyzing starch with ⁇ -amylase followed by hydrogenation of the thus treated dextrin.
• JP 62-091501 discloses an indigestible polysaccharide prepared by hydrogenating a starch hydrolyzate obtained from acid or enzyme saccharification of starch, e.g., reduced branched dextrin, in the presence of an acid catalyst, e.g., 0.3-0.5 wt% inorganic acid (e.g., phosphoric acid) or 5-20 wt% organic acid, (e.g., citric acid,) to produce a reduced starch hydrolyzate, which is then dried by heating to 130°C in a vacuum.
• an acid catalyst e.g., 0.3-0.5 wt% inorganic acid (e.g., phosphoric acid) or 5-20 wt% organic acid, (e.g., citric acid,)
• the dried product is then heated to 150°C-250°C for 1-3 hours to obtain a powdered indigestible polysaccharide comprising an aggregate of a non-reducing polymer of various degrees of polymerization, formed by rearrangement of the glucose residue of the non-reducing sugar mainly at the 1-6 linkage.
• oligosaccharide As used herein, is a saccharide - derivatized oligosaccharide which is described in U.S. Patent Application Publication No. U.S. 2004/0053866, the contents of which are incorporated by reference. It is a saccharide — derivatized mixture comprising the extrusion reaction product of a saccharide product having an average degree of polymerization ranging from 1 to 4 with a mixture of malto - oligosaccharide.
• a malto-oligosaccharide is a species comprising two or more saccharide units linked predominantly via 1-4 linkages. It is preferred that the maltooligosaccharide used is maltodextrin.
• the more preferred binders are indigestible dextrin polydextrose, the indigestible polysaccharide described in U.S. Patent No. 5,620,871, JP 62-091501 and JP 2001/086946 and the dextrinized oligosaccharide, maltooligosaccharides (maltodextrin), isomaltooligosaccharides, cyclodextrins, gentiooligosaccharides, nigerooligosaccharides, fructooligosaccharides, inulin, galactooligosaccharides, xylooligosaccharides, agarooligosaccharides, mannooligosacchradies, chitin/chitosan oligosaccharides, arbinogalactan and pullulan.
• maltooligosaccharides maltooligosaccharides (maltodextrin)
• polysaccharides examples include, but are not limited to, polydextrose, indigestible dextrin(s), and derivatives thereof, and combinations thereof.
• a most preferred polysaccharide is polydextrose.
• the most preferred binders are indigestible dextrin and especially polydextrose.
• the binder may consist of one polysaccharide or a combination of two or more polysaccharides as defined herein.
• the polysaccharide in whatever form utilized is substantially pure. It is preferred that they are substantially free of impurities. They are preferably at least about 80% pure and more preferably at least about 85% pure and most preferably at least about 90% pure.
• the binder can be purified using techniques known in the art. For example, among the purification processes used in the art, the following are preferred processes for purifying polydextrose: 1) bleaching, e.g. using hydrogen peroxide (described in U.S. Pat. No. 4,622,233); 2) membrane technology (described in U.S. Pat. No. 4,956,458); 3) ion exchange e.g. removal of citric acid (described in U.S. Pat. No. 5,645,647) or removal of color/ bitter taste (described in U.S. Pat. No.
• Figures 1 and 2 show the summary of linkages and branching in FIBERSOL-2 ® and polydextrose.
• the FIBERSOL-2 ® compared to polydextrose has higher amounts of unbranched and single branched residues, lower content of furanoses and greater amounts of 4- and 4,x- linked residues.
• polydextrose and FIBERSOL-2 ® are very closely related in structure and either can be used alone or in combination in the binder of the present topcoat composition.
• the polysaccharide e.g., polydextrose or derivatives thereof, e.g. LITES SE ® or LITESSE II ® , act as a binder. LITESSE II ® is preferred because of low costs.
• the indigestible dextrin or derivatives thereof e.g. FIBERSOL-2 ® , acts as a binder.
• the polydextrose or the indigestible polysaccharide, or the dextrinized oligosaccharide e.g., in the "binder" improves the film forming capability of the coating. Without wishing to be bound it is believed that its hydrophilic nature thereof facilitates the absorption of the ink jet ink by the coating during the ink jet printing process.
• the binder of the present invention comprised of polysaccharide, e.g., polydextrose, indigestible polysaccharide, dextrinized oligosaccharide or combination thereof is present in amounts effective to enhance ink jet printability and improve color development. It is preferred that the binder, i.e., polydextrose or indigestible polysaccharide or dextrinized oligosaccharide is present in the range from about 5% to about 93% on a parts by solid weight basis. The preferred concentration of the polydextrose and/or indigestible polysaccharide binder is about 50% to about 70% on a parts by solid weight basis.
• binders include, but are not limited to gums, cellulose derivatives, chitin, chitosan, dextran, pectin, agar-agar, arrowroot, guar, carrageenan, tragacanth, xanthan, gelatin, polyvinylpyrrolidone and copolymers thereof, and/or hydrophilic polymers such as polyvinyl alcohol (PVOH), polyvinyl pyrrolidone, gelatin, cellulose ethers, polyoxazolines, polyvinylacetamides, partially hydrolyzed polyvinyl acetate/vinyl alcohol, polyacrylic acid), polyacrylamide, polyalkylene oxide, sulfonated or phosphated polyesters and polystyrenes, casein, zein, albumin, and the like.
• PVOH polyvinyl alcohol
• PVOH polyvinyl pyrrolidone
• gelatin cellulose ethers
• polyoxazolines polyviny
• a topcoat is provided that is comprised of a mixture of a silica filler, and the binder is comprised of a polysaccharide, e.g., polydextrose or indigestible dextrin.
• the components can be dissolved, or dispersed into a solvent solution or carrier comprised of deionized water, a suitable alcohol or a combination of the two.
• Other components can be added to improve coating wet out (or spread) of the coating during application to the ink jet media base support layer, improve the pot life or working time of the coating during application, impart other properties to the coating or to modify the viscosity or solids content of the coating and/or act as a biocide agent.
• Drying and surface holdout of the printed inks on the topcoat are facilitated by the addition of a pigment or filler.
• the pigment or filler not only aids in surface holdout of the ink but also introduces pores or channels to the topcoat to aid in drying.
• the filler, i.e., silica, content of the invention results in the ink absorptive nature of the coating and is partially responsible for the permanent nature of the adhesion of the ink to the coated media base.
• the binder of the present invention e.g., polydextrose, aids in binding of the silica to the paper substrate.
• the preferred filler is silica.
• silica types are well known, available, and suitable for use such as fumed silica, precipitated silica, and silica gel.
• Silica types exhibit different pore sizes resulting in varying degrees of ink absorbing capabilities.
• a fumed silica gel dispersion particularly suitable for the present invention is CAB-O-SPERSE PGOOl (produced by the Cabot Corporation), which possesses high pore volume and ready dispersion into the solvent solution.
• Concentration of the silica filler component can range from about 0% to about 90% on a parts by weight basis and are covered under this invention.
• the preferred concentration of the silica gel filler is from about 25% to about 50%.
• other fillers may be used together in addition to the silica, including, but not limited to calcium carbonate, kaolin, and mixtures thereof.
• ingredients or additives may be added to avoid problems which occur during mixing and application such as improper wetting of the substrate surface, foaming of the composition when exposed to high mixing rates, adhesion of the dry composition to the substrate, and preservation of the components from biological attack (e.g. fungi).
• non-ionic surfactants, defoamers or preservatives may be added.
• An example of a defoamer suitable for the present invention is FOAMASTER 111 silicone based defoamer.
• An example of a suitable preservative for the present invention is PROXEL GXL.
• the ink jet printing media topcoat of the present invention can contain an additive such as a biocide, an anti-curling agent or anti-blocking agent.
• the topcoat can also contain other additives known to those skilled in the art to improve the print image, such as, but not limited to, for example, UV absorbers, optical brighteners, light stabilizers, antioxidants, humefactants, spacing agents, plasticizers, dye mordants, fixatives, dispersants, rheology modifiers, leveling agents and the like.
• the ink jet topcoat also includes a surfactant to charge the pigment.
• Preferred surfactants are nonionic. However, cationically or anionically charged surfactants can also be used.
• An example of a suitable surfactant includes, but is not limited to, polyethylene glycol (TRITON X-100 ® ) (DOW-UCAR). The surfactant is employed at a concentration of about 0.1% to about 5% on a parts by weight basis, and more preferably at about 0.5% to about 2% on a parts by weight basis.
• the topcoat of the present invention includes a biocide agent.
• biocide agent is PROXEL GXL ® (l,2-Benzisothiazolin-3- one, produced by Avecia Biocides), with a concentration in a range of about 0% to about 1 % on a parts by weight basis.
• the topcoat solvent or carrier liquid can be deionized water, monohydric alcohol, polyhydric alcohol or a combination thereof. Preferred is deionized water. Typical concentration of the solvent or carrier liquid can range from about 50% to about 85% on a parts by weight basis. Deionized water is preferably ion-exchanged water of which the Ca +2 ion and Mg +2 ion contents have been reduced to not more than about 5 ppm.
• the topcoat coating will preferably have a dried thickness of about 0.1 to about 0.5 mils, or from about 2 to about 13 grams/square meter. However, topcoat thickness in a range from about 1 to about 25 grams/square meter or more can be effective. Actual topcoat coating thickness within this range can be variable based on the specific ink jet media base being coated. The invention covers all ranges of dried coating thicknesses as noted.
• the topcoat of the present invention is formulated by adding the silica filler component to deionized water while mixing under a mild level of agitation until homogeneous.
• the binder is then added to the deionized water solution and mixed under a mild level of agitation until homogeneous. Mixing is performed with a spindle with multiple blades in an open vessel. The rate of mixing is that which results in a homogeneous mixture without inducing foaming.
• the addition of other components, as noted earlier, including surfactants, biocides, and the like, are added in succeeding steps as required to improve the coatability, or extend the pot life/stability of the coating.
• the order of adding additives is based on ingredient functionality.
• the defoamer is added to deionized water prior to the addition of the polysaccharide and, optionally, additional binders to inhibit the foaming from the addition of those ingredients.
• Cationic mordants such as AgeflexTM are added subsequent to the silica filler to inhibit flocculation of the silica particles.
• the total solids content of the compounded ink jet topcoat composition can range from about 10% to about 50% on a parts by weight basis.
• the viscosity of the compounded topcoat can range from about 10 to about 20 cps (centipoise). Both the solids content and the viscosity of the compounded topcoat can be varied or adjusted based on actual coating requirements dictated by the method of applying the topcoat composition to ihe ink jet media base layer that is to be coated.
• the invention can be applied, or coated onto an ink jet media base support layer using a variety of commonly known coating techniques.
• the ink jet media, or base support layer can be an uncoated paper, a coated paper (coated on one side or two sides), a polymer film, a laminate of paper and film or other suitable material useful in ink jet printing.
• Preferred substrates are paper and paper type media.
• Topcoat application techniques that can be used include, but are not limited to, wire wound rod, metering bar, knife over roll, direct gravure, reverse gravure, reverse roll and multiple roll methods, and air knife. These coating methods can be employed as a secondary process to apply, or coat the topcoat composition onto an ink jet media base after manufacturing of the media base.
• the ink jet topcoat of the present invention can also be applied to a paper ink jet media base in a size press during the media manufacturing process of a base paper.
• the ink jet topcoat of the present invention can be applied to the ink jet media base during a secondary printing, or converting operation, during which the ink jet media can undergo actual printing and die-cutting operations after application of the topcoat as in the case of labels. The ink jet topcoat would then be applied prior to the printing, and die cutting operations.
• topcoat of the present invention can be applied to one or both sides of the media substrate. Additionally, other coats such as anti-curl coats can be applied.
• the ink jet topcoat After application of the ink jet topcoat to, and absorption by, the ink jet media base layer the ink jet topcoat is dried to drive off the solvent carrier liquid from the topcoat composition.
• the drying process can be accomplished through the use of any drying method known to those skilled in the art. Preferred are evaporative drying processes. Drying processes that can be used in the present invention include, but are not limited to, air drying, convection, radio frequency, or infrared methods. [0080] Noting that to date, no unifying theory that explains molecular interactions which take place between the ink jet medium topcoat and the medium itself, the present invention should not be limited to a particular theory of operation.
• the ink jet printing ink (dye or pigment based) coloring material should be retained on the surface of a recording medium in a monomolecular state without aggregation.
• Chroma can be lowered.
• compositions of the invention results from the presence of the binder, i.e., a polysaccharide, e.g., specific range of linear and branched oligomers, and low to high molecular weight range (DP distribution) in poly dextrose or FIBERS OL-2 ® combined with its highly amorphous nature which inhibits aggregation of the coloring material.
• a polysaccharide e.g., specific range of linear and branched oligomers
• DP distribution low to high molecular weight range
• the most preferred binder is polydextrose.
• polydextrose When polydextrose was used as the binder in topcoat compositions, prepared in accordance with the present invention, formulation evaluations showed polydextrose to function as an effective binder for paper ink jet media coatings. Without wishing to be bound, it is believed that polydextrose is preferred due to its natural affinity for paper and its effectiveness in solubilizing water- based dyes.
• a preferred ink receptive coating is formulated containing polydextrose.
• black pigment ink hold out on the printed surface was optimized via modification of the coating formulation with cationic dye mordant and use of polyvinyl alcohol (PVOH) as a co-binder.
• PVOH polyvinyl alcohol
• Physical properties include, but are not limited to, curl (ASTM D 4825), blocking (ASTM D 918), and smoothness (TAPPI T-538).
• the ink receptive layer can absorb water in the air and swell in an environment of high relative humidity, causing curling. Sheffield smoothness is a measurement of pressurized air flow over the surface under prescribed conditions.
• Paper samples coated with the composition of the present invention containing polysaccharide or combination thereof as the binder and a filler comprised of silica showed improved printing quality in most aspects.
• Print quality assessments include curl, feathering, mottling, wet or dry cockle, image bleed, banding, bronzing, skew or artifacts.
• Feathering is a phenomenon that is evidenced primarily in printed text and is caused by ink flowing along fibers in the paper.
• Visual evidence of feathering is small protrusions around the edges of a printed image.
• Mottling is defined as printing defects resulting in non-uniform print density of a solid filled area.
• Coalescence is defined as printing defects caused by pooling of ink in areas on the surface of the paper.
• Wet cockle is evidenced by wave patterns during application of wet ink to the paper surface. Dry cockle is the result of non-uniform print densities arising from wet cockle. Image bleed can be visually evidenced by the mixing of one ink color with another adjacent ink color. Bleed is usually a result of severe feathering. Banding is evidenced by regions of bands of varying print density in a solid filled area. Bronzing is the appearance of a bronze sheen to solid filled black print areas. Skew relates to the position of printed images to the border of the paper. Artifacts include any droplets or ink spray located in unprinted areas of the paper. Issues relating to mottling/coalescence and wet/dry cockle are likely due to the coating techniques used.
• composition of the present invention provided enhanced print quality, decreasing the amount of and more preferably minimizing the amount of curl, feathering, mottling, cockling, bleeding, banding, bronzing, and the presence of artifacts relative to a composition in which the silica and polysaccharide binder are not present.
• the overall print quality of paper coated with the polysaccharide, e.g., polydextrose, formulation was compared to that of commercial ink jet printable paper and showed the following advantages: (1) improved printability; (2) improved printed color purity (Chroma) for dye-based inks; and (3) comparable-to-improved physical properties over commercially available ink jet printable papers.
• ink jet printing media which the print receptive topcoat of the present invention can be applied to. It is understood that the media can be paper, card, stock, metal, wood, plastic, or film.
• percent on a weight basis as used herein is meant percentages in the composition which includes the liquid carrier component.
• An ink jet receptive top coating for paper was formulated as set forth in Table 1.
• Polydextrose was formulated with the nonionic surfactant polyethylene glycol (TRITON ® ) (Dow), fumed silica (CAB-O-SIL ® ) (Cabot Corporation), and abiocide (PROXEL GXL ® ) (l,2-Benzisothiazolin-3-one, Avecia Biocides).
• Viscosity has a potentially large effect on determination of application method of a coating to paper. Increasing the solids content in formulations with polydextrose caused only a slight increase in viscosity. This indicates that a broad range of coating application technologies and methods are potentially suitable for the deposition of a polydextrose-based binder topcoat to the ink jet media base.
• Patent Formulation PVOH I (WO 95/06564)
• Patent Formulation PVP I (US 4775594)
• Patent Formulation PVP II (WO 02/43965)
• Formulation F coating overall exhibited improved (the best) dye-based color ink appearance as well as inferior pigment-black ink appearance when compared to the patent formulations.
• the visual appearance of printed samples was slightly better than formulations based on PVP alone, however, the visual appearance was not comparable to printed sample with PVOH and PVP co-binders in the top coating.
• Formulation F at slightly higher solids than the three patent formulations, exhibited the lowest viscosity.
• Formulations involving PVOH or PVP are well known for exhibiting viscosity increases with increasing solids levels.
• Formulations with polydextrose do not exhibit this trend.
• Polydextrose contains high concentrations of free hydroxyl groups that can potentially be used in crosslinking polymer chains. Titanates, an example being TYZOR ® product line (DuPont) and isocyanates, an example being DESMOD LJR ® (Bayer) are widely known and used for crosslinking of hydroxyl chemistries. Various crosslinkers were evaluated with Formulation F at concentrations known to those in the art. Evaluation of thermally crosslmked coatings shows no visual improvement of the pigment-based black ink hold out on the surface.
• Cationic mordants are well known in the ink jet receptive coating industry for use in anchorage of anionic dye-based inks (U.S. Pat. Nos. 4,554,181, 5,474,843, 5,747,148, 5,795,425 and 5,908,723).
• Examples of cationic mordants are AGEFLEX ® products (Ciba Specialty Chemicals).
• Ageflex FA lq75MC is N 5 N- Dimethylaminoethyl Methacrylate Methyl Chloride Quaternary. These chemicals are also known to have flocculation properties when used in the paper processing industry.
• cationic mordants can be mutually beneficial for anchorage of anionic dye-based inks to the paper base along with potential flocculation of the pigment present in the black ink to aid in surface hold out.
• Formulations produced with various mordants result in improvements hi pigment hold out on the surface.
• Issues with pigment anchorage to the surface of the paper were seen with formulations containing mordants.
• a small percentage of PVOH was added as a co- binder to aid in overall anchorage of the ink to the paper substrate.
• the resulting optimized Formulation J depicted in Table 10 exhibited improved pigment-black ink hold out without diminishing the visual integrity of the dye-based inks.
• the ink receptive layer can absorb water in the air and swell in an environment of high relative humidity, causing curling.
• curl was seen to be in the machine direction of the paper in all cases.
• None of the three papers studied exhibited any inter-sheet adhesion (i.e. blocking) when tested under 0.5 pounds per square inch at 140 0 F, 75% relative humidity for 21 hours. Sheffield smoothness is a measurement of pressurized air flow over the surface under prescribed conditions.
• Overall results were comparable between the three papers with the exception of the smoothness of the sample coated with Formula J which can be expected to yield an improved ink jet printed image. Paper samples coated with Formula J showed comparable-to-improved physical properties when compared with commercially available topcoated ink jet printing papers.
• Print quality assessments of the three papers were made based on ASTM F
• Rankings were assigned to each property based on severity. A ranking of 1 correlates to the effect not evidenced or low severity whereas a ranking of 3 correlates to severe visual evidence of the effect. A more detailed effect-by-effect assignment of rankings can be found in the ASTM F 1944 procedure.
• Optical testing of printed Formulation J coated paper shows improved chroma values for all colors evaluated with two different types of dye-based ink.
• chroma evaluations were performed on the various colors printed on the three papers. Chroma is generally referred to as color purity. Higher chroma values correlate to higher purity in color, a richer or denser color rendition.
• the three papers were printed with the HP DeskJet 6122 printer as aforementioned and chroma evaluated. Results are found in Table 13. Table 13 Chroma Data for Various Printed Colors

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• 2005
  • 2005-12-08 JP JP2007545605A patent/JP2008522876A/ja active Pending
  • 2005-12-08 EP EP05853299A patent/EP1827862A4/en not_active Withdrawn
  • 2005-12-08 AU AU2005314092A patent/AU2005314092A1/en not_active Abandoned
  • 2005-12-08 WO PCT/US2005/044344 patent/WO2006063096A1/en active Application Filing
  • 2005-12-08 KR KR1020077015794A patent/KR20070106997A/ko not_active Application Discontinuation
  • 2005-12-08 CA CA002589934A patent/CA2589934A1/en not_active Abandoned
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