WO2001053893A1 - Plaques d'impression revetues polyvalentes pour imprimantes electrophotographiques et presses offset - Google Patents

Plaques d'impression revetues polyvalentes pour imprimantes electrophotographiques et presses offset Download PDF

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Publication number
WO2001053893A1
WO2001053893A1 PCT/US2001/001521 US0101521W WO0153893A1 WO 2001053893 A1 WO2001053893 A1 WO 2001053893A1 US 0101521 W US0101521 W US 0101521W WO 0153893 A1 WO0153893 A1 WO 0153893A1
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WO
WIPO (PCT)
Prior art keywords
printing sheet
multifunctional
image receptive
pigment
receptive coating
Prior art date
Application number
PCT/US2001/001521
Other languages
English (en)
Inventor
Stanley R. Stevens
Original Assignee
S. D. Warren Services Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by S. D. Warren Services Company filed Critical S. D. Warren Services Company
Priority to AU2001232829A priority Critical patent/AU2001232829A1/en
Publication of WO2001053893A1 publication Critical patent/WO2001053893A1/fr

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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
    • B41M5/50—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
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H19/00—Coated paper; Coating material
    • D21H19/36—Coatings with pigments
    • D21H19/38—Coatings with pigments characterised by the pigments
    • D21H19/385—Oxides, hydroxides or carbonates
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G7/00—Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
    • G03G7/0006—Cover layers for image-receiving members; Strippable coversheets
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G7/00—Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
    • G03G7/0006—Cover layers for image-receiving members; Strippable coversheets
    • G03G7/0013—Inorganic components thereof
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G7/00—Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
    • G03G7/0006—Cover layers for image-receiving members; Strippable coversheets
    • G03G7/002—Organic components thereof
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G7/00—Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
    • G03G7/0006—Cover layers for image-receiving members; Strippable coversheets
    • G03G7/002—Organic components thereof
    • G03G7/0026—Organic components thereof being macromolecular
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M1/00—Inking and printing with a printer's forme
    • B41M1/06—Lithographic printing
    • 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
    • B41M5/5236—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
    • 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

  • the present invention relates to a high quality coated printing sheet. More particularly, the present invention relates to multifunctional coated printing sheets for use in electrophotographic printers, i.e., monochromatic or color printers or copiers, and in conventional offset printing presses. The present invention further relates to a method of manufacturing such a multifunctional coated printing sheet.
  • Electrophotographic printing is one of the primary methods of electronic, or digital, monochromatic and color copying and printing. Electrophotographic printing may employ dry toner technology, i.e., xerography, or liquid toner technology.
  • Electrophotographic printing generally includes seven steps to reproduce or print an image: (a) charging a photoreceptor; (b) exposing an image with a light source, e.g., a light emitting diode, a fluorescent light or a laser, on the surface of the photoreceptor to form a charged latent image on the surface; (c) developing the latent image with a toner of opposite charge; (d) transferring the charged toner image to a paper sheet, the sheet having a charge opposite to that of the toner; (e) fusing the toner to the sheet; (f) erasing the latent image from the photoreceptor; and (g) cleaning the residual toner from the photoreceptor.
  • a light source e.g., a light emitting diode, a fluorescent light or a laser
  • the electrophotographic printer is referred to as a laser printer.
  • a transport system is required to feed the sheet into the printer, to transport the sheet through the printer and to deliver the printed sheet to an output tray.
  • a feed belt e.g., friction or vacuum belt
  • the feed belt may be controlled by a timing mechanism in order to stop it momentarily to allow spacing between sheets.
  • a jam in an electrophotographic printer is generally a mistiming event which encompasses a variety of problems, e.g., a misfeed, loss of traction during transport through the printer, or an actual physical jam of the paper in the printer, all of which may cause the electrophotographic printer to shut down.
  • the primary cause of jams is typically a misfeed of the paper, e.g., double feeding, a physical jam, or slippage in the paper feed tray.
  • a coated printing sheet that provides the desired printed product attributes and performs well in both offset printing presses and electrophotographic printers allows printers to minimize paper inventories.
  • such a coated printing sheet may be used for sequential printing. For instance, printed material for the print-on- demand market is often the result of a two stage process. First, the primary images, typically color images, and text are printed on conventional offset printing presses. Then the variable data, e.g., personalized information such as the recipient's name and address, are added by electrophotographic printers.
  • Coated printing papers designed for use in conventional offset printing presses tend to jam in electrophotographic printers.
  • Good runnability is critical for large scale commercial electrophotographic printing operations because runnability directly affects productivity, e.g., downtime required to address jams, and cost, e.g., labor and equipment damage.
  • productivity e.g., downtime required to address jams
  • cost e.g., labor and equipment damage.
  • a coated printing sheet that exhibits comparable runnability to that of an uncoated sheet, i.e., essentially jam-free performance, in electrophotographic printers.
  • a coated printing sheet includes platy pigment, i.e., a pigment material in which the particle shape resembles a plate having a diameter that is much greater than its thickness
  • platy pigment i.e., a pigment material in which the particle shape resembles a plate having a diameter that is much greater than its thickness
  • runnability in electrophotographic printers is adversely affected.
  • the inventor has found that by substantially reducing the amount of platy pigment in the coating, a coated printing sheet may be provided which exhibits good runnability in electrophotographic printers, e.g., runnability comparable to that of an uncoated sheet. Without intending to be bound by any particular theory, this phenomenon appears to be related to contamination of the transport system in an electrophotographic printer by platy pigment material, which may cause slippage of the sheets during transport. Such slippage may lead to "out of sequence" timing which may cause the printer to shut down.
  • the present invention provides multifunctional coated printing sheets suitable for use in both electrophotographic printers and in conventional offset printing presses.
  • multifunctional coated printing sheet means a coated printing sheet that is suitable for use in electrophotographic printers and in conventional offset printing presses.
  • Preferred multifunctional coated printing sheets of the invention provide runnability characteristics comparable to those of an uncoated printing sheet in most electrophotographic printers.
  • the multifunctional coated printing sheets also exhibit the surface and optical properties, e.g., paper gloss, brightness, opacity and smoothness, required of conventional offset printing grades, and provide a surface that is image receptive and resistant to coating failure or picking, i.e., localized delamination of the coating layer from the underlying substrate during toner fusing in electrophotographic printers or during ink transfer in offset printing.
  • the invention further provides methods for manufacturing such multifunctional coated printing sheets.
  • the invention provides a multifunctional coated printing sheet including a substrate and, on at least a first surface of the substrate, an image receptive coating, wherein the multifunctional printing sheet exhibits runnability characteristics comparable to those of an uncoated printing sheet in electrophotographic printers.
  • the invention provides a multifunctional coated printing sheet including a substrate and, on at least a first surface of the substrate, an image receptive coating including a binder and a non-platy pigment, wherein the coating includes 100 parts of pigment, of which 10 parts or less are a platy pigment, wherein the multifunctional printing sheet exhibits runnability characteristics comparable to those of an uncoated printing sheet in electrophotographic printers.
  • the invention provides a multifunctional coated printing sheet including a substrate and, on at least a first surface of the substrate, an image receptive coating including a binder and a non-platy pigment, wherein the coating is substantially free of a platy pigment, wherein the multifunctional printing sheet exhibits runnability characteristics comparable to those of an uncoated printing sheet in electrophotographic printers.
  • the substrate is paper.
  • the multifunctional printing sheet provides the surface and optical properties required of conventional offset printing grades.
  • the multifunctional printing sheet provides a surface that is image receptive and resistant to coating failure.
  • the term "parts," as used herein, means dry parts based on 100 parts of pigment.
  • the coating includes 100 parts of pigment, of which at least 75 parts are a non-platy pigment selected from the group consisting of natural ground calcium carbonate, precipitated calcium carbonate and mixtures thereof.
  • Preferably at least 90 parts of the non-platy pigment is a pigment selected from the group consisting of precipitated calcium carbonate and mixtures of natural ground calcium carbonate and precipitated calcium carbonate.
  • the non-platy pigment is a mixture of natural ground calcium carbonate and precipitated calcium carbonate, and the precipitated calcium carbonate component comprises at least 50% of the total mixture.
  • the remainder of the pigment consists of non-platy pigments selected from the group consisting of calcined clays, structured clays, titanium dioxide, satin white, hollow sphere plastic pigments, solid plastic pigments, silicas and mixtures thereof.
  • the coating includes about 6 to 20 parts of a binder, preferably about 9 to 15 parts.
  • the binder includes a latex, selected from the group consisting of styrene butadiene, styrene butadiene acrylonitrile, styrene acrylic, styrene butadiene acrylic and mixtures thereof, and a water soluble or water miscible co-binder, selected from the group consisting of starches, polyacrylate salts, polyvinyl alcohol, carboxymethyl cellulose, hydroxymethyl cellulose and mixtures thereof.
  • the latex comprises at least 50% of the total binder, more preferably at least 75% of the total binder.
  • the co-binder includes 3 parts or less of a starch.
  • the substrate has an ash content of about 10 to 18%, preferably about 12 to 15%.
  • the image receiving coating has a total dried coat weight of about 8 to 15 g/m 2 , preferably about 10 to 12 g m 2 .
  • the multifunctional coated printing sheet has a final moisture level of about 3.0 to 4.5%, preferably about 3.5 to 4.0%.
  • the invention provides a method of manufacturing a multifunctional coated printing sheet including: a) applying an image receptive coating to at least a first surface of a substrate; and b) drying the image receptive coating layer, wherein the multifunctional printing sheet provides runnability characteristics comparable to those of an uncoated printing sheet in electrophotographic printers.
  • the invention provides a method of manufacturing a multifunctional coated printing sheet including: a) applying an image receptive coating, comprising a binder and a non-platy pigment, to at least a first surface of a substrate, wherein the image receptive coating includes 100 parts of pigment, of which 10 parts or less are a platy pigment; and b) drying the image receptive coating layer, wherein the multifunctional printing sheet provides runnability characteristics comparable to those of an uncoated printing sheet in electrophotographic printers.
  • the invention provides a method of manufacturing a multifunctional coated printing sheet including: a) applying an image receptive coating, comprising a binder and a non-platy pigment, to at least a first surface of a substrate, wherein the image receptive coating is substantially free of a platy pigment; and b) drying the image receptive coating layer, wherein the multifunctional printing sheet provides runnability characteristics comparable to those of an uncoated printing sheet in electrophotographic printers.
  • Preferred methods may include one or more of the following features.
  • the multifunctional printing sheet provides the surface and optical properties required of conventional offset printing grades.
  • the multifunctional printing sheet provides a surface that is image receptive and resistant to coating failure.
  • a calendering step is performed after the drying step.
  • the calendering step is performed by a soft nip calendering unit.
  • the calendering step is performed by a soft nip on-line calender, at a nip pressure of about 175 to 440 kN/m, an operating roll temperature of about 150 to 250 °C, and an incoming web moisture of about 4 to 6%.
  • the nip pressure is about 315 to 385 kN/m and the operating roll temperature is about 175 to 220 °C.
  • the final product moisture of the multifunctional printing sheet after calendering is about 3.0 to 4.5%, preferably about 3.5 to 4.0%.
  • a brushing step is performed before or after the calendering step, preferably after the calendering step.
  • the net specific brushing intensity applied to the substrate during the brushing step is about 0.005 to 0.07 kW hr/m 2 .
  • the invention provides a method of using a multifunctional coated printing sheet including: a) printing a first image on the multifunctional printing sheet in an offset printing press; and b) printing a second image on the multifunctional printing sheet in an electrophotographic printer, wherein the multifunctional printing sheet provides runnability characteristics comparable to those of an uncoated printing sheet in electrophotographic printers.
  • the multifunctional coated printing sheets exhibit runnability characteristics comparable to those of an uncoated printing sheet in electrophotographic printers, provide the surface and optical properties expected for conventional offset printing grades, and provide a surface that is image receptive and resistant to coating failure.
  • the image receptive coating of the multifunctional printing sheets provides adequate toner adhesion, i.e., the printed images tend to be resistant to scratching and the toner typically does not flake off the coated surface at creases or folds made through image areas.
  • the multifunctional coated printing sheets are suitable for offset printing, which typically requires a smooth and image receptive surface.
  • Embodiments of the invention may satisfy the requirements of a premium, #1, #2 or #3 grade, as such grades are designated by the industry based on sheet brightness and aesthetic criteria such as paper surface quality and final printed image quality.
  • the image receptive coating of the multifunctional coated printing sheets exhibits sufficient ink transfer, i.e., the absorption of the ink-fountain solution mixture by the surface is such that a uniform film of ink is transferred from the printing blanket to the sheet during offset printing, and sufficient ink holdout, i.e., the printing ink remains on the surface of the coating.
  • the multifunctional coated printing sheet comprises a substrate and, on at least a first surface of the substrate, an image receptive coating including a binder and a non-platy pigment.
  • the coating may further include 10 parts or less of a platy pigment, e.g., clay, kaolin, bentonite, alumina trihydrate or talc.
  • a platy pigment e.g., clay, kaolin, bentonite, alumina trihydrate or talc.
  • the coating is substantially free of platy pigment.
  • Suitable non-platy pigments include ground calcium carbonates, precipitated calcium carbonates, calcined clays, structured clays, titanium dioxide, satin white, hollow or solid plastic pigments, silicas and mixtures thereof. Suitable non-platy pigments provide the optical properties required of offset printing grades, such as brightness and opacity. Suitable non-platy pigments enhance the surface coverage of the substrate by the coating layer as well as improve image receptivity of the coating. Practitioners skilled in the art are aware of how to select the appropriate non-platy pigments to achieve the desired final product attributes.
  • the coating comprises 100 parts of pigment, of which at least 75 parts, more preferably at least 90 parts, are a non-platy pigment, selected from the group consisting of natural ground calcium carbonate, precipitated calcium carbonate and mixtures thereof. It is most preferred that the non-platy pigment comprise a mixture of natural ground calcium carbonate and precipitated calcium carbonate, and that the precipitated calcium carbonate comprise at least 50% of the total mixture.
  • a high proportion of precipitated calcium carbonate in the coating is preferred because such coatings tend to provide improved optical product attributes and to exhibit improved fiber coverage of the substrate. Improved fiber coverage permits the use of lower coat weights, resulting in a greater fiber-to-coating ratio for the sheet. A greater proportion of fiber in the sheet tends to increase the overall stiffness of the sheet. However, an excessively high proportion of precipitated calcium carbonate may negatively affect other desirable final product attributes such as paper gloss.
  • Calcium carbonates are commercially available in a broad range of surface areas, average particle sizes and particle size distributions. Precipitated calcium carbonates tend to have smaller surface areas than ground calcium carbonates. Typically, the surface area of the precipitated calcium carbonate ranges from about 8.0 to 12.0 m 2 /g, and the surface area of the ground calcium carbonate ranges from about 10.0 to 16.0 m 2 /g. Preferably the surface area of the precipitated calcium carbonate is about 9.0 to 10.0 m 2 /g, and the surface area of the ground calcium carbonate is about 12.0 to 14.0 m 2 /g. Typically the equivalent spherical diameter (ESD) of the calcium carbonate particles is less than about 2 ⁇ m.
  • ESD equivalent spherical diameter
  • the particles Preferably, for glossy coated printing sheets, about 90 to 95% of the particles have an ESD of less than 2 ⁇ m. Preferably, for matte coated printing sheets, about 65% of the particles have an ESD of less than 2 ⁇ m. If the distribution of calcium carbonate particles is skewed to a larger particle size, the paper gloss may be affected deleteriously. If the distribution of calcium carbonate particles is skewed to an excessively small particle size, there is an increased tendency for coating defects, e.g., blade scratches, during the application of the coating to the paper substrate. Practitioners skilled in the art are aware of how to select the appropriate particle size distribution to achieve the desired product attributes and to minimize coating defects.
  • the calcium carbonate pigment will exhibit a relatively narrow particle size distribution.
  • a narrow particle size distribution in the coating tends to improve fiber coverage and to enhance optical properties. If the particle size distribution is too narrow, the application of the coating to the substrate may be negatively affected, e.g., poor coat weight control and blade scratches due to poor water retention of the coating layer. If the particle size distribution is too broad, the particles exhibit more efficient packing within the coating layer which may lead to a more dense, less porous coating resulting in a deterioration of fiber coverage. Reduced porosity may also affect the ability of moisture within the printing sheet to escape during printing. When moisture cannot escape rapidly, blistering, i.e., disruptions in the printed image caused by the delamination of the coating layer from the underlying substrate, may result.
  • Suitable precipitated calcium carbonates are manufactured by J.M. Huber Corporation, Specialty Minerals, Inc. and Imerys Pigments, Inc.
  • Suitable ground calcium carbonates are commercially available from Imerys Pigments, Inc. and Omya Incorporated.
  • Preferred calcium carbonates enhance the optical properties of the sheet, such as brightness, improve coating bulk, and improve toner adhesion in electrophotographic printers.
  • a bulky coating typically has a more open pore structure which tends to enhance toner adhesion and to improve blister resistance.
  • the ground calcium carbonates will exhibit a blocky, i.e., irregular spherical, shape.
  • Precipitated calcium carbonates are commercially available in an array of particle shapes.
  • the precipitated calcium carbonates will exhibit a rhombohedral shape.
  • the image receptive coating includes plastic pigments, hollow sphere or solid.
  • Suitable plastic pigments enhance the surface and optical properties of the image receptive coating, such as gloss, opacity, smoothness and bulk.
  • the average particle size of solid plastic pigments ranges from 0.13 to 0.50 ⁇ m.
  • Suitable solid sphere plastic pigments are commercially available from The Dow Chemical Company, e.g., Dow 722, and from Omnova Solutions, Inc., e.g., Lytron 2503.
  • the average particle size typically ranges from about 0.5 to 1.0 ⁇ m with a shell thickness of about 0.06 to 0.09 ⁇ m.
  • the hollow core diameter typically ranges from about 0.38 to 0.82 ⁇ m, resulting in void volumes of about 43% to 55%.
  • Preferred hollow sphere plastic pigments have an average particle size of about 1.0 ⁇ m and a void volume of about 50% to 55%.
  • Suitable hollow sphere plastic pigments are commercially available from Rohm and Haas Company, e.g., Ropaque HP-1055 and Ropaque HP-543P.
  • the binder component of the coating includes a coating latex.
  • the amount of binder in the coating is about 6 to 20 parts, more preferably about 9 to 15 parts.
  • the amount of binder in the coating should provide adequate coating strength to resist picking, i.e., localized delamination of the coating layer from the underlying substrate, during the manufacturing process and during printing.
  • Typical monomers used in the production of latex polymers for paper coatings include styrene, butadiene, acrylonitrile, butyl-acrylate, methyl methacrylate, vinyl acrylic, isoprene and combinations thereof.
  • Preferred latexes permit the use of a coating with high solids level while maintaining acceptable viscosity.
  • Preferred latexes also provide aesthetically desirable surface qualities to the final coated printing sheet, such as gloss, brightness and smoothness.
  • Preferred latexes include styrene butadiene, styrene butadiene acrylonitrile, styrene acrylic, styrene butadiene acrylic and mixtures thereof.
  • the glass transition temperature of the latex, Tg falls within the range of 5 to 25°C. If the Tg is too low, the latex when dry tends to be tacky which affects the tackiness of the dried coating, e.g., the dried coating layer may stick to further processing rolls, thereby decreasing the final gloss of the sheet. If the Tg is too high, the latex when dry tends to resist molding which provides a high final gloss but reduces the coating strength.
  • the mean particle size of the latex particles, for glossy coated printed sheets is typically about 1600 to 2000 angstroms, preferably about 1800 angstroms.
  • the mean particle size of the latex particles, for matte coated printed sheets is typically about 1000 to 1400 angstroms, preferably about 1200 angstroms. Coatings with smaller latex particles typically exhibit improved coating strength because smaller particles provide a greater surface area per unit weight with which to bind the other coating components. Improved coating strength tends to reduce the occurrence of picking in the offset printing press.
  • Suitable latexes include: Dow 620NA, Dow 640NA, and Dow 615, manufactured by The Dow Chemical Company; Gen-Flo 5086, Gen-Flo 8045, and GenCryl 9710, manufactured by Omnova Solutions Inc.; and Acronal S504, Acronal S728, and Styronal 4664 manufactured by BASF Corporation.
  • the binder component of the coating may further include a water-soluble or water-miscible co-binder, selected from the group consisting of a starch, polyacrylate salt, polyvinyl alcohol, carboxymethyl cellulose, hydroxymethyl cellulose and mixtures thereof.
  • Suitable starches include pearl, ethylated, oxidized or enzyme treated starch, all of which may be derived from potato, corn, rice or tapioca starches.
  • Co-binders are typically used to manipulate coating rheology and water retention of the coating.
  • the amount of starch in the co-binder is about 3 parts or less.
  • the brightness and gloss of the coating may be substantially reduced and a lower coating solids is often required which deleteriously affects fiber coverage.
  • the latex component of the binder comprises the greater proportion, e.g., at least 50%, more preferably at least 75 % of the total weight of binder. Practitioners skilled in the art are aware of how to select the appropriate binder and co-binder package to achieve the desired coating rheology.
  • the coating may further include optical-related coating additives, such as colorants, tinting dyes, fluorescent brighteners, blooming agents and mixtures thereof. Practitioners skilled in the art are aware of how to select the appropriate optical package to achieve the desired final product attributes, such as shade and brightness.
  • the coating may further include coating additives, such as dispersants, thickeners, defoamers, water retention agents, preservatives, crosslinkers, lubricants and pH control agents. Practitioners skilled in the art are aware of how to select the appropriate coating additives to meet manufacturing and production objectives, e.g., to control foam, rheology, dusting, calender releasability, and to achieve the desired final product attributes.
  • the substrate is preferably a paper substrate of a weight and type suitable for offset printing.
  • the basis weight of suitable substrates typically ranges from about 65 to 325 g/m 2 , preferably about 65 to 216 g/m 2 .
  • the ash content of the substrate i.e., the amount of inorganic material incorporated within the substrate, including virgin pigment material and pigment material derived from a recycled fiber component of the substrate, is about 10 to 18%, more preferably about 12 to 15%. If the ash content of the substrate is too high, the stiffness of the substrate may decrease significantly. If the ash content is too low, the optical properties, e.g., opacity and brightness, of the sheet may be adversely affected, and the cost of production may increase.
  • the substrate may further include a precoat or a base coat layer.
  • a precoat layer may enhance the surface strength of the coating layer, e.g., to resist picking, increase coating holdout (i.e., the ability of the coating to remain on the surface of the substrate rather than striking into the substrate), and improve optical properties of the final printing sheet, such as gloss, opacity and brightness.
  • Practitioners skilled in the art are aware of how to select the appropriate precoat or base coat formulation to achieve the desired balance of surface strength, coating holdout and final optical properties. If both sides of the substrate are coated with the image receiving coating layer, the formulation of the precoat or base coat is unrestricted. If only one side of the substrate is coated, preferably the other side does not include a precoat or base coat, or the precoat or base coat does not contain any platy material.
  • the image receptive coating is applied to the substrate using an on-machine or off-machine coater.
  • suitable coating techniques include an applicator means, e.g., applicator roll, fountain, jet, slotted die, and curtain, and/or a metering means, e.g., bent blade, bevel blade, rod, roll, short dwell, air knife, bar, gravure, size press (conventional or metering), and air brush.
  • the coating layer is applied by a bent blade/applicator roll coater.
  • the coating may be applied in one or more layers.
  • the total coat weight applied per side is about 8 to 15 g/m 2 , more preferably about 10 to 12 g/m 2 .
  • the solids level of the coating will typically range from about 55 to 70%; a coating with a lower solids is typically used when the coating is applied in more than one layer.
  • the coating is applied to both sides of the substrate to ensure that the printed images on both sides of the printing sheet are of comparable quality.
  • the coating layer is then dried, e.g., by convection, conduction, infrared, or combinations thereof.
  • a calendering step may be performed after the substrate has been coated and dried.
  • the calendering apparatus may be a separate supercalender, an off-line soft nip calender, or an on-line soft nip calendering unit.
  • the level of calendering performed on the sheet is dependent on the desired product attributes, such as paper gloss and sheet bulk.
  • Suitable supercalenders consist of alternating steel and non-metal rolls, e.g., cotton, cotton-wool or plastic shell, creating about 9 to 13 nips.
  • Suitable soft nip calenders, on-line or off-line consist of pairs of rolls, each pair including a heated metal roll against a compliant plastic composite roll, creating 2 to 8 nips, preferably 4 nips.
  • typical supercalender process conditions include a bottom nip pressure range of 175 to 440 kN/m, steel roll temperatures of about 65 to 95 °C, and an incoming web moisture of about 4 to 6%.
  • the nip pressures range from about 175 to 440 kN/m
  • the operating roll temperature ranges from about 150 to 250 °C
  • the incoming web moisture is about 4 to 6%.
  • the coated printing sheet is soft nip calendered on-line, with a nip pressure of 315 to 385 kN/m, and an operating roll temperature of about 175 to 220 °C.
  • the final product moisture of the printing sheet after the calendering step ranges from about 3.0 to 4.5%, more preferably 3.5 to 4.0%.
  • Practitioners skilled in the art are aware of how to select the appropriate calendering conditions, e.g., web speed, web moisture, nip pressure and calendering temperature, to achieve the desired final product attributes.
  • a brushing step may be performed after the substrate has been coated and dried.
  • the brushing step is performed before or after the calendering step, more preferably after the calendering step.
  • the brusher apparatus may be a separate apparatus, or a process unit in a continuous line. Brushing may be used to achieve the desired levels of paper gloss and smoothness at a higher bulk than may be achieved through calendering alone. Brushing intensity is controlled by three variables: brushing area, i.e., the surface area of the coated substrate in contact with the brushes; brushing force, i.e., the tangential force applied by the brushes against the surface of the coated substrate; and brush speed.
  • Net specific brushing intensity is calculated from the net power of the brusher motor, the substrate web speed, and the width of the substrate web.
  • the net specific brushing intensity applied to the substrate is about 0.002 to 0.1 kW hr/m 2 , more preferably about 0.005 to 0.07 kW hr/m 2 . If the brushing intensity is too low, the desired level of gloss and smoothness may not be achieved. If the brushing intensity is too high, the surface of the image receiving layer may be damaged, e.g., scratches and streaks, and undesirable dusting may occur.
  • Suitable brushers typically have a plurality of brush rolls, e.g., four to eight brush rolls, and are commercially available from DOX Maschinenbau GmbH.
  • the coated printing sheet of the invention may be printed on one or both surfaces of the substrate.
  • the coated printing sheet of the invention may be printed in an offset printing press, in an electrophotographic printer or both. Because both offset printing presses and electrophotographic printers are available in web or sheetfed models, the coated printing sheet may be supplied in web form or in sheet form.
  • Sequential printing typically requires a multifunctional printing sheet.
  • the printing sheet is (a) printed in an offset printer, (b) cut into a size acceptable for electrophotographic printers, and (c) printed in an electrophotographic printer, e.g., monochromatic and/or color printers. If a web offset printer and a web electrophotographic printer are available, a cutting step between the printing steps is unnecessary.
  • the multifunctional coated printing sheet is generally supplied in large sheet form. After offset printing, the large sheets are cut to the appropriate size by a guillotine cutter and printed in an electrophotographic printer.
  • the multifunctional coated printing sheet is supplied as a roll of paper.
  • the printed web of paper is cut to the appropriate size in a sheeter and printed in an electrophotographic printer.
  • contamination e.g., dirt, dried coating debris and loose fibers
  • Color electrophotographic sheetfed printers often have two printing speed settings; a high speed setting typically used for uncoated sheets and a low speed setting typically used for heavier or coated sheets. Regardless of the speed setting, complete toner fusing of the toner to the image receptive coating is particularly important for color electrophotographic printing. If toner fusing is inadequate, the quality of the printed images may be adversely affected, e.g., the images may exhibit mottle, unprinted areas, picking in image areas, and low toner gloss. Another problem that may arise during printing in color electrophotographic printers is blistering.
  • the multifunctional coated printing paper of the invention provides an acceptable image receptive surface without blistering at both the low and high speed settings in a color electrophotographic printer.
  • Table 1 below provides coating formulations and final product attribute data for four embodiments of the invention.
  • the paper was soft nip calendered on-line under the following conditions: a nip pressure of 175 kN/m; a temperature of about 218 °C for the heating medium in the heated rolls; 4 nips total; and a web speed of about 610 m/min.
  • the substrate for Example A was manufactured on a different papermachine, which may have caused some differences in product attributes typically affected by substrate differences.
  • Tobias Microgloss is a measure of the point-to-point variation in gloss, using a 1.5 mm microgloss head in the Tobias Mottle tester. The lower the value, the more uniform is the surface gloss.
  • Opacity and brightness measurements were performed according to Tappi Methods T-425 and T-452 om-87, respectively.
  • the measurements for 75° gloss were performed on unprinted paper.
  • the measurements for 75° ink gloss were performed on a single color ink (magenta) solid image, which was printed on a Vandercook proofing printing press and air-dried. Both the 75° gloss and 75° ink gloss measurements were performed according to Tappi Method T-480.
  • the measurements for the 60° toner gloss were performed using a BYK Gardner Micro-TRI-Gloss meter on a single color black image printed at the high speed setting on a DocuColor 40 color electrophotographic printer manufactured by Xerox Corporation.
  • a glossier unprinted paper surface is indicated by a higher 75° gloss value.
  • PPS Parker Print Surface
  • PPS measurements were performed according to Tappi Method T-555om-94.
  • the measurements for Lorentzen & Wettre (L&W) stiffness were performed according to method DIN-53-1221. L&W stiffness is the bending force which results when a sample is subjected to a bending angle of 15°, and a higher value indicates greater stiffness.
  • the product attributes provided in Table 1 are typically used to differentiate between coated printing sheets for offset printing.
  • glossy coated printing papers suitable for offset printing exhibit brightness greater than about 82.0, 75° gloss greater than about 65.0, 75° ink gloss greater than about 90.0, and PPS smoothness less than about 1.20.
  • Matte coated printing papers suitable for offset printing typically exhibit brightness greater than about 82.0, 75° gloss equal to or less than about 50.0, 75° ink gloss greater than about 50.0, and PPS smoothness less than about 4.0.
  • the data in Table 1 demonstrates that the multifunctional coated printing sheets of the invention would be considered suitable for offset printing.
  • the smoothness data is particularly notable because this data indicates that the coated printing sheets of the invention are very smooth, as required for offset printing. Contrary to expectations, such magnitude of smoothness does not adversely affect runnability in electrophotographic printers for the multifunctional coated printing sheets of the invention. Surface roughness is typically considered necessary for acceptable runnability in electrophotographic printers.
  • the toner gloss data is also noteworthy because the samples were printed at the high speed setting, typically the most demanding printing condition. Although the toner gloss decreases initially during a print job, the level of toner gloss would be considered acceptable. Furthermore, blistering did not occur during printing in the color electrophotographic printer.
  • Coated printing paper of the invention coated with the formulation for Example C described in Table 1, was evaluated on a high speed monochromatic electrophotographic printer, e.g., DocuTech 135 printer manufactured by Xerox Corporation.
  • the DocuTech 135 offers two feeding mechanisms, the friction retard and the vacuum-assisted mechanisms.
  • the examples listed in Table 2 were evaluated using the friction retard system, which tends to exhibit a greater propensity for jams with uncoated paper.
  • the coated printing paper of the invention is Example E. Runnability results for comparative examples F and G, which were evaluated at the same time and on the same equipment, are also provided.
  • Example F is a commercially available uncoated paper
  • Example G is a commercially available coated paper manufactured by S.D.
  • Warren Company which includes more than 10 parts of a platy pigment in the coating.
  • the table shows the number of sheets that were attempted to be printed, the number of sheets that were successfully printed, and the number of jams. In all cases, unprinted paper was evaluated. It is expected that jam rates would be different for previously printed sheets because the printing inks would affect the characteristics of the sheet.
  • Example G had numerous jams, more attempts were made to run successfully. However, after 7000 sheets, the run was aborted because of the high number of jams and concerns about potential equipment damage.
  • the runnability data indicates that the coated printing sheet of the invention, which contains no platy pigment material, has comparable runnability to that of uncoated sheets.
  • coated printing sheets of the invention are suitable for use in flexographic printing presses.
  • Various modifications of this invention will become apparent to those skilled in the art without departing from the scope or spirit of this invention.

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Abstract

L'invention porte sur une plaques d'impression revêtues polyvalentes pour imprimantes électrophotographiques en couleur ou monochromes et presses offset classiques. Lesdites plaques, aux possibilités comparables à celles des plaques non revêtues de la plupart des imprimantes électrophotographiques, présentent par ailleurs les propriétés superficielles et optiques requises pour les grades d'impression des presses offset et une surface photosensible et résistante aux défauts de revêtement. Lesdites plaques comportent un substrat, et au moins sur l'une de leurs surfaces, une couche photosensible composée d'un liant et d'un pigment non lamellaire, ladite couche étant pratiquement exempte de pigments lamellaires. L'invention porte également sur le procédé de fabrication desdites plaques.
PCT/US2001/001521 2000-01-19 2001-01-16 Plaques d'impression revetues polyvalentes pour imprimantes electrophotographiques et presses offset WO2001053893A1 (fr)

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AU2001232829A AU2001232829A1 (en) 2000-01-19 2001-01-16 Multifunctional coated printing sheets for use in electrophotographic and offsetprinters

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US48784000A 2000-01-19 2000-01-19
US09/487,840 2000-01-19

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Cited By (3)

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Publication number Priority date Publication date Assignee Title
US7744688B2 (en) 2002-12-27 2010-06-29 Imerys Pigments, Inc. Paper coating pigments
WO2013105912A2 (fr) 2011-11-29 2013-07-18 Hewlett-Packard Development Company, L.P. Procédés d'amélioration de brillance de feuille
US20140370273A1 (en) * 2012-10-18 2014-12-18 Imerys Pigments, Inc. Coating composition and coated paper and coated paperboard

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US4778711A (en) * 1986-02-26 1988-10-18 Fuji Xerox Co., Ltd. Paper for receiving toner images in electrophotography
EP0621510A1 (fr) * 1993-04-23 1994-10-26 Nippon Paper Industries Co., Ltd. Papier pour transfert et son procédé de préparation
EP0711672A2 (fr) * 1994-11-08 1996-05-15 Nippon Paper Industries Co., Ltd. Papier d'enregistrement et son procédé de préparation
EP0718700A2 (fr) * 1994-12-20 1996-06-26 Fuji Xerox Co., Ltd. Papier de transfert électrophotographique
US5643631A (en) * 1995-03-17 1997-07-01 Minerals Tech Inc Ink jet recording paper incorporating novel precipitated calcium carbonate pigment
WO2000004231A1 (fr) * 1998-07-17 2000-01-27 Ecc International Ltd Materiaux de pigmentation et leur mise en application dans des compositions de revetement

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Publication number Priority date Publication date Assignee Title
US4778711A (en) * 1986-02-26 1988-10-18 Fuji Xerox Co., Ltd. Paper for receiving toner images in electrophotography
EP0621510A1 (fr) * 1993-04-23 1994-10-26 Nippon Paper Industries Co., Ltd. Papier pour transfert et son procédé de préparation
EP0711672A2 (fr) * 1994-11-08 1996-05-15 Nippon Paper Industries Co., Ltd. Papier d'enregistrement et son procédé de préparation
EP0718700A2 (fr) * 1994-12-20 1996-06-26 Fuji Xerox Co., Ltd. Papier de transfert électrophotographique
US5643631A (en) * 1995-03-17 1997-07-01 Minerals Tech Inc Ink jet recording paper incorporating novel precipitated calcium carbonate pigment
WO2000004231A1 (fr) * 1998-07-17 2000-01-27 Ecc International Ltd Materiaux de pigmentation et leur mise en application dans des compositions de revetement

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7744688B2 (en) 2002-12-27 2010-06-29 Imerys Pigments, Inc. Paper coating pigments
EP1579070B1 (fr) 2002-12-27 2017-02-15 Imerys Pigments, Inc. Pigments d'enduit pour papier
WO2013105912A2 (fr) 2011-11-29 2013-07-18 Hewlett-Packard Development Company, L.P. Procédés d'amélioration de brillance de feuille
EP2785530A4 (fr) * 2011-11-29 2015-07-08 Hewlett Packard Development Co Procédés d'amélioration de brillance de feuille
US20140370273A1 (en) * 2012-10-18 2014-12-18 Imerys Pigments, Inc. Coating composition and coated paper and coated paperboard
US10450704B2 (en) 2012-10-18 2019-10-22 Imerys Usa, Inc. Coating composition and coated paper and coated paperboard
US10519603B2 (en) 2012-10-18 2019-12-31 Imerys Usa, Inc. Coating composition and coated paper and coated paperboard

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