Classifications

• • 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
• • 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
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/63—Inorganic compounds
• • 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
  • 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
• • 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
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/14—Secondary fibres
• • 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
  • D21H19/80—Paper comprising more than one coating
  • D21H19/84—Paper comprising more than one coating on both sides of the substrate

Definitions

• the invention relates to a paper for digital printing process.
• This digital printing paper can be processed as sheets or as roll paper.
• Digital printing paper is made up of a carrier or base paper whose surface is painted. It is used, for example, as printer paper for business papers.
• Digital printing processes use toner or ink, such as B. be used in laser printers or inkjet printers.
• the carrier or base paper must be sufficiently strong and have a given volume.
• the fibers of the backing paper cause the strength. Fillers bring the opacity and reduce costs.
• a significant cost factor of digital printing paper are the fibers used to make the backing paper.
• the carrier paper of the digital printing paper has to absorb high loads. In particular, it must carry the fillers and the coating application and must not tear when conveying the paper by printers or printing presses.
• z. B. in the EP 0785 307 or the DE 197 45 082 is sought to use high amounts of cheap filler, but the least possible amounts of coating order, since pigments that have a higher tinctorial strength than fillers, significantly more expensive than fillers. To get along with the least possible coating order, even the backing paper should be as light as possible or white.
• the coating application ensures a uniformly bright, as white as possible surface and thus the precise acquisition and recording of the ink or the toner or the ink.
• the requirements for a surface suitable for digital printing are manifold. In particular, it must be ensured that the finest lines and precise contours can be imaged.
• the ink or toner needs to be recorded smoothly and quickly.
• pigments or mixtures of pigments are used, which are possibly mixed with binder and to give the paper as evenly bright surface, which is well suited for receiving toner or ink. Pigments are among the cost-intensive constituents of printing paper.
• High-performance inkjet printers print more than 500 sheets / minute, often over 1,000 sheets / minute, and certainly more than 2,000 sheets / minute. They thus penetrate into the performance range previously reserved for offset printing and strive to at least partially replace offset printing.
• inkjet printers use ink or high liquid content pigments or very low viscosity liquids (water) to print on the paper.
• the known digital printing papers do not sufficiently absorb this particularly high liquid content of the ink used for the ink-jet printing, or make the ink penetrate on the other side.
• the print will be blurred if the printed sheets are stacked in quick succession, or the sheets can not be printed on both sides. Therefore, the technical capabilities of these printers can not be exploited.
• the paper according to the invention is particularly absorbent and ensures a contour sharp, low-running printing.
• the ink does not strike the back of the paper.
• the paper of claim 1 is skinned thin so that the fibers of the backing paper are not completely covered by the coating application.
• the secondary fibers which are not completely covered by the coating application, absorb the liquid of the ink of the ink jet printer extremely fast.
• the pigments contained in the ink therefore probably settle in the majority on the surface of the paper according to the invention, which is formed from coating application and fibers or fiber sections.
• the paper according to the invention wipes immediately after printing and can be printed at speeds of 2000 sheets / minute and more in inkjet printers, without causing the blur of the printed image.
• Fresh or primary fibers are wood or annual plants mechanically or chemically produced fibers. They are used for the first time (fresh) for the production of paper, cardboard or cardboard.
• secondary fibers are in particular fibers that have already been processed once into paper or paperboard. The paper or paperboard was dissolved, eventually ink or paint removed, and the fibers re-processed into paper or paperboard. Paper, paperboard, dissolving and reprocessing make paper from secondary fibers shorter, less firm and darker than paper from primary long fiber pulps. Secondary fibers, mostly waste paper fibers, are cheaper available and also environmentally friendly in the treatment.
• a paper for digital printing in which the fibers of the backing paper are at least 50% by weight secondary fibers thus reduces the cost of the paper for digital printing and is environmentally friendly.
• This advantage can - as well as the printability properties of the invention - Be used better if at least 60% by weight, preferably at least 75% by weight, advantageously at least 90% by weight of the fibers of the backing paper are secondary fibers.
• the backing paper can also be made entirely from secondary fibers without further ado.
• All types of secondary fibers are suitable for the production of the backing paper.
• waste paper but also rags can be used.
• the carrier paper other fibers added, it may be fresh or primary fibers, but also be synthetic fibers.
• the paper for digital printing according to the invention contains fillers. These are partly introduced via the secondary fibers, which frequently carry up to 20% by weight of filler.
• the secondary fibers are obtained by dissolving paper in water or alkaline liquor, de-inking the fibers if necessary, and removing ink and contaminants from the suspension.
• the processed so Secondary fibers are then either used directly as a suspension for the production of the paper according to the invention or they are dried, stored or transported and then re-suspended in aqueous solution before processing. Deinkening does not always remove all fillers or the entire spread of the deinked paper, so the secondary fibers carry up to 20% by weight of fillers. This is to be taken into account when setting a predetermined filler content for the paper for digital printing. It is also preferred for the filler used for the first time in the backing paper according to the invention that the use of optical brighteners is not necessary since, according to a preferred embodiment, no high degrees of whiteness are required for the digital printing paper.
• the fillers used are light white particles, most commonly calcium carbonates, both natural (GCC) and precipitated (PCC) calcium carbonates, or kaolin. Typically, mixtures of different fillers are used. Overall, the content of filler in the paper support paper for digital printing may be 50% by weight.
• the paper for digital printing according to the invention is provided on one or both sides with a coating application of up to 8 g / m 2 per side of the carrier paper.
• the application is at least 0.5 g / m 2 per side.
• a dispersion is usually prepared from white pigments or mixtures of pigments on the one hand and binders or mixtures of binders on the other hand, which is applied in liquid form to the backing paper. So usually white coated paper is then dried and possibly the surface is compacted, for. B. by calendering.
• a pigment known coating pigments such as PCC, GCC, kaolin, titanium dioxide can be used individually or in mixture.
• binders known binders can be used. Starch is preferably used as a binder, but also latex, polyvinyl alcohols or crosslinkers or mixtures thereof are well suited.
• the coating application may be designed to achieve whiteness for the finished high performance ink jet printer paper of 60% ISO or more, if desired also at least 70% ISO or at least 80% ISO.
• these values are achieved without the use of optical brighteners.
• the digital printing paper according to the invention can have a sheet weight of 50 g / m 2 up to 180 g / m 2 . In this area, it is particularly well suited for use in high-speed inkjet printers. It is sufficiently stiff, in both the longitudinal and transverse directions, to be processed in high speed inkjet printers.
• the paper of the present invention is particularly suitable for use in high speed ink jet printers which print more than 500 sheets per minute, typically more than 1,000 sheets or even 2,000 sheets per minute.
• the suitability of papers to be tested for the particular printer or printing equipment such as offset, laser or inkjet printer is tested by printing with a uniform standard.
• These standards or test images are designed so that parameters such as acutance, color density, color intensity, print gloss and the like are verifiable.
• the following evaluations of various parameters relate to the printing of a sheet of paper with such a test pattern or standard.
• An essential property of the paper according to the invention relates to the application of printing ink.
• the surface of the paper according to the invention and the composition of the backing paper of 50% or more secondary fibers determine the speed at which the applied printing ink or printing ink dries.
• the drying takes place in less than 0.1 seconds, preferably in less than 0.06 seconds, advantageously in less than 0.03 seconds. A lower limit is noticeable at 0.001 seconds.
• the drying time was determined in field tests by printing in each case 5000 sheets or a corresponding amount of this web of the paper to be tested by means of a high-performance inkjet printer with a test pattern and optionally cut at the end of the printing process.
• the sheets of paper printed with the same test pattern are visually inspected for clearness of the printed image or smudges.
• Typical high-performance inkjet printers suitable for testing the drying time are z.
• the Océ Jetstream 2200, InfoPrint 5000 of IBM / Ricoh or HP T 300 machines can each print approximately 2,700 A4 sheets per minute in color. These inkjet printers are about to replace offset printing equipment because they have comparable performance.
• the rapid drying is probably due to the good fluid conduction through the thin coat application and the good absorbency of the secondary fibers in the backing paper. Again, it should be noted that the moisture introduced by ink does not adversely affect the strength of the base paper or its dimensional stability.
• the contour sharpness (also called line sharpness or color gradient test) is determined in such a way that the extent of a printed line relative to a reference line is detected.
• Contour sharpness is an essential parameter to assess the suitability of a paper for high-speed inkjet printers.
• the good contour sharpness described above can not be achieved with known printing papers for digital printers. It is also unexpected because professionals do not consider secondary fibers suitable for reproducing good contour sharpness due to their good suction power.
• the paper according to the invention for digital printing has advantageous despite the thin coating application and a possibly smoothed, z.
• the calendered surface has a uniform surface that uniformly accepts toner or printer ink.
• the surface of the paper hardly shows any mottling.
• Mottling refers to highly compressed surface sections that are color-coded from the surface. They give the paper a dirty appearance. In addition, they take ink, toner or printer ink differently than the rest of the paper surface, creating an uneven print image.
• the mottling which is visually determined by viewing the surface, is less than 3% of the paper surface tested in the paper of the invention. As a rule, it is less than 1% of the tested paper surface.
• the paper for digital printing according to the invention preferably has a high optical density.
• the optical density indicates to what extent or intensity applied ink, toner or printer ink is recorded and reproduced on or through the paper surface.
• the scale for the measure of the rendering is dimensionless and is 0 to 2, where 2 is the 100% representation.
• the norm to be applied is ISO / CD 5-3, status T, status I or status E, with status T predominantly used in the US. Here was measured with the usual E status for Europe.
• the values listed below were recorded with the Gretag Macbeth D 19 D Densitometer, filter set type 47 B / P, 0 ° / 45 ° ring optics according to DIN 16536 "Testing of Printing and Inks of Printing Techniques - Color Density Measurement on Prints".
• the paper according to the invention reaches a value of at least 0.4, preferably more than 0.8, preferably more than 1.0.
• These good values for paper may be explained by the fact that the good absorbency of the secondary fibers absorbs the liquid from the ink jet ink so quickly and completely that there is a sharp separation of pigments or dyes and liquid, so that more pigments are present on the surface of the printing paper remain as in known papers. There, slow picking up of inkjet ink may cause enough time for settling effects, which causes pigments to be dragged through the liquid to or into the fiber. They are therefore no longer available on the surface of the paper.
• the paper according to the invention has high color fidelity or color fastness, which is also measured and designated as color tone reproduction.
• the measuring specification here is DIN 6174 "Colorimetric determination of color dimensions and color distances in approximately uniform CIELAB color space.” Measured here was a spectrophotometer Elrepho SE 070, diffuse illumination, 0 ° measurement, standard illuminant D65. The measurement correlates the brightness and readings for the red-green axis and the blue-yellow axis of the object being inspected and indicates the total color distance. The measured values are dimensionless and can reach up to 6-digit values, easily up to more than 200,000.
• the paper has a color intensity of at least 100,000, preferably of at least 120,000, advantageously of at least 150,000.
• the printed paper has a much higher gloss than the unprinted paper.
• the print gloss gloss of the printed paper
• the print gloss is more than 5, preferably more than 10, advantageously more than 15 based on the gloss of the unprinted paper.
• the print gloss is determined by the surface of the paper according to the invention. This paper is printed with a given standard or test pattern and the print gloss is measured. Although the printed paper is measured, this parameter relates to a property of the unprinted paper of the present invention, since the color rendition is directly dependent on the substrate on which it is applied. For the paper according to the invention, the measured values are unusually high; Experts had suggested lower levels given the higher proportion of secondary fibers compared to known digital printing papers.
• the paper for digital printing on a high pick resistance which makes it suitable for use in digital printers.
• the picking strength - measured according to ISO 3783 - records how much the printers use the surface of the paper when applying printing ink or toner or printing ink. As by fibers or particles from the surface of the paper dissolved out (plucked).
• the paper for digital printing according to the invention has a picking strength of less than 4.0.
• the pick resistance is less than 2.0, more preferably less than 1.0.
• the low pick resistance is astonishing since the paper according to the invention has a high proportion of secondary fibers or consists of secondary fibers which are shorter than primary fibers and therefore could be more easily leached out of the fiber composite of the carrier paper.
• the coating is very thin, so that the applied pigments or the mixture of pigments and binders can cover and protect the fibers only little. The good pick resistance was therefore unexpected.
• Backing paper A has 55% secondary fibers and 45% primary fibers, each based on the total amount of fibers.
• Carrier paper B has 75% secondary fibers and 25% primary fibers.
• Backing paper C has 90% secondary fibers and 10% primary fibers.
• Carrier paper D has 100% secondary fibers.
• the primary fibers used are chemically produced softwood fibers (pulp) bleached to whiteness 90% ISO.
• filler is also added to the aqueous suspension.
• the suspension contains 30% by weight of filler based on the dried paper.
• Half of the filler is introduced by the secondary fibers.
• the other half of the filler consists of a kaolin-carbonate mixture.
• the suspension is dewatered and Papers A, B, C and D are produced with a sheet weight of 80 g / m 2 each and dried to a moisture content of 2% by weight. These papers are then each provided with a coating order.
• a slurry of PCC, GCC and kaolin in equal parts, containing no optical brightener, is applied to both sides of the support papers in an amount of 3 g / m 2 .
• the coated papers are again dried and smoothed. The smoothing is done with a calender with a line pressure of about 100 N / m.
• the finished sheets have a whiteness of 80% ISO. When using high quality, white waste paper, the whiteness of the finished sheets can also be over 100% ISO.
• drying time of the paper according to the invention is much lower than the drying time of the commercial reference paper. It is assumed that the greatly shortened drying time also leads to sharpness of contour and color intensity as well as optical density showing markedly improved values compared with the prior art or the reference paper.
• the rapid separation of liquid and solid phase (pigments) of the inkjet ink on the paper according to the invention can lead to these parameters showing better values than in the case of the reference paper. The differences are significant and show significantly better print results than in the prior art.

Landscapes

• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Paper (AREA)
• Ink Jet Recording Methods And Recording Media Thereof (AREA)

Priority Applications (1)

Applications Claiming Priority (1)

Publications (1)

Family

ID=43736138

Family Applications (1)

Country Status (1)

Citations (8)

• 2011
  • 2011-01-11 EP EP11150546A patent/EP2474667A1/fr not_active Withdrawn

Patent Citations (8)

Similar Documents

Legal Events