Classifications

• • 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
  • G03G7/004—Organic components thereof being macromolecular obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • 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
• • 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
• • 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
  • G03G7/0033—Natural products or derivatives thereof, e.g. cellulose, proteins

Definitions

• This invention relates to a versatile ink-jet printing paper, i.e. to paper which is specially adapted to give good imaging performance when used with an ink jet printer, but which also exhibits good toner adhesion when imaged by electrophotographic processes as used in laser printers, xerographic copiers and such like.
• Ink-jet printers will produce an image on most papers, but the print quality varies markedly in dependence on the nature of the paper used.
• print quality is meant factors such as the sharpness, intensity and uniformity of the image produced and its susceptibility to smudging immediately or shortly after the ink has been applied.
• colour printing it is important also that the colours should not run into one another and that they should be vivid, with good brightness.
• Print quality is influenced by a number of factors, but the two most important are the extent to which the ink droplets spread out after contact with the paper and the rapidity with which the ink droplets are absorbed into the paper. Excessive droplet spreading resulting from, for example, flow of ink along the length of the paper fibres, produces an image which appears blurred, with fuzzy edges, spidery lines and a general lack of resolution (this is often referred to as feathering or wicking, and the effect is somewhat analogous to that obtained by writing with a fountain pen on blotting paper).
• pigment coating makes the paper highly absorptive to the aqueous ink vehicle, so that the vehicle drains away quickly into the body of the paper, leaving the coloured dye at the surface and thereby giving bright intense colours with minimal print bleed.
• pigment coating has not been found essential for good quality black (monochrome) images, it does generally enhance the quality of those images compared with those obtained on uncoated papers.
• a pigment coating is disadvantageous in certain respects, in that it adds to raw material and process costs, and tends to give rise to "dusting" problems in subsequent conversion and printing operations, i.e. pigment particles can become dislodged from the coating and deposit on reeling, slitting and printing equipment.
• AKD sizing offers the papermaker many benefits compared with traditionally rosin-alum sizing, it is important that it should be possible to utilise AKD sizing in the production of papers for office use, and that a solution should be found to the problem of achieving good ink-jet printing performance and good toner adhesion in the same product.
• toner adhesion is particularly difficult to achieve with rough papers which carry a surface-profile texture, for example a laid line, chain line or other pattern applied by means of a dandy roll, or a pattern applied by felt marking or wet or dry embossing. This is probably because toner adhesion is normally achieved by heat- and/or pressure-fusion of the toner to the paper. With rough or surface-textured papers, it is difficult to achieve sufficiently good physical contact for this fusion to be effective.
• the present invention provides, in a first aspect, an ink-jet printing paper of which the print-receiving surface comprises a base paper treated with a composition comprising an admixture of:
• the present invention provides a method of producing ink-jet printing paper, comprising the step of treating at least the print-receiving surface of a base paper with a composition comprising an admixture of:
• the treatment composition is conveniently applied to the paper by means of a size press, but other techniques can be used, for example spraying or coating.
• size press in this context includes modified size presses or coating heads as supplied, for example, by Voith under the name “Speedsizer”, Valmet under the name “Sym-sizer”, Jagenberg under the name “Filmpress” and BSG under the name “Twin HSM”.
• Cooked and/or chemically modified starches are widely used in the paper industry and are thus very well-known. They are to be distinguished from particulate starches as found in plants (such particulate starches are the raw material from which cooked and/or chemically modified starches are produced). Dextrins, although derived from starches, are not considered to be "cooked and/or chemically modified starches" in this context, since the hydrolysis processes involved in their production result in loss of essential starch character.
• Suitable starches for use in the treatment composition are generally those used in the paper industry as surface sizes, as coating binders, or as wet-end additives. Surface-sizing starches are currently preferred. The starches can be anionic, cationic, amphoteric or non-ionic in character. A preferred surface sizing starch for use in the present invention is an anionic oxidised potato-based starch. Other suitable surface sizing starches are oxidised maize or wheat starches.
• the hydrophilic polymer for use in the treatment composition is preferably a polyvinyl alcohol, more preferably a relatively low molecular weight partially-hydrolysed polyvinyl alcohol with a degree of hydrolysation of around 88%, or 87-89% as it is often expressed in manufacturer's product information sheets.
• Other hydrophilic polymers which can be used include dextrin, cellulose derivatives such as carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC) ; gelatin; vegetable gums such as gum arabic; polyvinylpyrrolidones; and maleic anhydride copolymers, for example copolymers of maleic anhydride with ethylene (EMA), or vinyl methyl ether (PVMMA).
• the hydrophobic polymer for use in the treatment composition is preferably a latex, typically a latex of the kind supplied for use as a paper coating binder or as a surface sizing additive.
• Suitable latexes include styrene-acrylic copolymer latexes of various kinds (including acrylonitrile/n-butylacrylate/styrene copolymer latex); styrene-butadiene copolymer latexes; and polyurethane latexes.
• the relative proportions of the starch, hydrophilic polymer and hydrophobic polymer can vary quite widely, although the starch is normally the major component of the composition, usually making up at least 50% of its total weight on a dry basis.
• the amount of hydrophobic polymer present can vary quite widely, depending on the degree of hydrophobicity of the polymer. For example, the amount of hydrophobic polymer required when the polymer is a polyurethane is much less than when the polymer is a styrene-acrylic or carboxylated styrene-butadiene material.
• the treatment composition should contain from about 50 to about 90% by weight starch, from about 5 to about 50%, more preferably 5 to 25%, by weight of a hydrophilic polymer such as polyvinyl alcohol, and from about 2 to about 40% of hydrophobic polymer, all these percentages being on a dry basis.
• a hydrophilic polymer such as polyvinyl alcohol
• hydrophobic polymer all these percentages being on a dry basis.
• the amount of polyvinyl alcohol used can vary quite widely, as indicated, cost factors would normally lead to usage in the lower part of the range quoted.
• the amount of hydrophobic polymer used will depend in part on its degree of hydrophobicity. In general the amount used will be in the range 2 to 30% by weight.
• the treatment composition is made up at a solids content of about 5 to about 15% by weight, although this is not believed to be critical.
• the treatment composition can include a small proportion of pigment such that the weight of pigment in the composition is less, normally much less, than the aggregate dry weight of the starch, the hydrophilic polymer and the hydrophobic polymer.
• the weight ratio of pigment : aggregate dry weight of starch, hydrophilic and hydrophobic polymer may be, for example, about 1:20, although the precise ratio is not thought to be critical. The inclusion of a minor proportion of pigment in this way can in some cases enhance the ink-jet printing performance of the paper still further.
• the present treatment composition can be used to enhance the ink-jet printing performance of a wide variety of papers for office or other business use.
• the base paper is an around 80 to 100 g m -2 woodfree base which has been conventionally internally sized, for example with alkyl-ketene dimer or a rosin/alum sizing system.
• Hard sizing is preferable, for example to a Cobb value (60 seconds) in the range 15 to 30.
• the pulps used and their relative proportions can vary widely, but a typical furnish would comprise 80% hardwood pulp and 20% softwood pulp. Usual papermaking fillers and other additives can be present.
• the treatment composition is preferably present in an amount of 1 to 5%, more preferably 2 to 4%, by weight of the base paper on a dry basis.
• the dry pick-up should preferably be from about 2 g m -2 to 4 g m -2 , on a dry basis (i.e. 1 or 2 g m -2 per side). Higher pick-up levels are technically acceptable but may be economically disadvantageous.
• the paper can be preferably calendered after treatment and subsequent drying, for example to a Bendsten roughness value of 500 ml min -1 or less.
• the paper can be one which carries a surface-profile texture as referred to earlier.
• the polyvinyl alcohol or other hydrophilic polymer promotes a controlled penetration of the ink but without much lateral spreading. If hydrophilic polymer is omitted, penetration is poor and the ink drying time is too long and an undesirable degree of mottle results. Thus although bright colours may be obtained, differently-coloured inks remain on the paper surface for sufficient time to run into and merge with one another, i.e. print bleed occurs. This is not a problem with monochrome inks, but the tendency of the ink to stay at the paper surface may give rise to smudging of the image.
• the benefits of the present invention are thought to accrue from the presence of a complementary balanced combination of hydrophilic and hydrophobic elements.
• the starch component of the composition is thought to contribute primarily the normal benefits of a starch sizing agent, i.e. it fills in pores and voids at the sheet surface and thereby provides a physical impediment to liquid penetration, sticks down loose fibres, and enhances the strength of the final paper.
• acrylonitrile/n-butylacrylate/styrene copolymer latex (“Acronal* S 360 D” supplied by BASF) were added with stirring, to give a treatment composition of a little under 15% solids content and a viscosity of about 80 cps (measured at 20°C, Brookfield viscometer, Spindle No. 2, speed 100 rpm).
• This treatment composition was then applied to a sheet of 100 g m -2 white uncoated woodfree general office base paper using a laboratory size press.
• the base paper was internally sized with alkyl ketene dimer, but had not previously been surface sized.
• the treated sheet was then dried using a laboratory rotary dryer. The dry pick-up was found to be about 5% (i.e. about 2.5 g m -2 per side), based on the dry weight of the base paper before treatment.
• the treated paper had a 60 second Cobb value of 18.
• the treated sheet was then laboratory calendered. After calendering the sheet had a Bendsten roughness of 150 ml min -1 .
• the sheet and a control sheet which had been treated with a conventional starch sizing composition were then printed by means of a Hewlett Packard* Deskjet* 560C ink jet printer.
• the printed images were of a standard test card giving both colour and monochrome (black) images and specifically designed to evaluate print quality and reveal failings in intensity, sharpness, wicking, print bleed and such like.
• the paper according to the invention was found to give rapid ink drying (i.e. penetration into the paper), good colour intensity, low ink bleed, and sharply defined colour and monochrome characters, with little wicking and low mottle, i.e. non-uniformity in print intensity in different areas of the paper. There was little or no strike-through of the ink to the reverse (unprinted) surface of the sheet.
• control sheet showed more print bleed and less bright colours on colour-printed areas.
• the monochrome image quality was quite good (probably a consequence of the internal sizing of the paper) but had a longer "drying time". This would be likely to give rise to smudging in everyday use.
• the other mix components were the same starch and polyvinyl alcohol as used in Example 1.
• the treatment compositions were prepared by the same general procedure as described in Example 1, but the final solids content was a little lower (about 12%).
• the % dry composition of the compositions was as follows: Component Mix I Mix II Mix III Starch 77.5 55 55 Polyvinyl alcohol 20.0 15 15 Latex 2.5 30 30
• the polyurethane has a higher degree of hydrophobicity than the other two polymers, and so it was used in a much smaller quantity.
• Each treatment composition was applied to a respective sheet of 95 g m -2 white uncoated woodfree premium business stationery base paper which had been internally hard sized with alkyl ketene dimer, but which had not been surface sized.
• the dry pick-up was found to be about 4% (i.e. about 2 g m -2 per side).
• the sheets were each laboratory calendered to a Bendsten roughness of around 150 ml min -1 .
• Example 1 The various sheets, together with a control sheet which was conventionally starch-sized, were then printed and evaluated as described in Example 1. All three papers according to the invention were found to give the same good performance as described in detail in Example 1, and the same benefits over the control paper.
• Example 1 This illustrates the use of the present invention on a full-size papermachine, using a treatment composition with the same ingredients and relative proportions as set out in detail in Example 1 (55 parts anionic oxidised potato starch, 15 parts 88 Mol% hydrolysed low molecular weight polyvinyl alcohol, and 30 parts latex, all on a dry basis).
• the solids content of the composition was 12%.
• Toner adhesion was also evaluated.
• the toner adhesion test also known as the tape pull test, involved printing a solid block of toner onto each sheet by means of a Hewlett-Packard LASERJET* IV laser printer; measuring the print density by means of an image intensity measuring instrument; applying adhesive tape to the sheet over the block-imaged area; carefully removing the tape with the aid of an Instron peel force tester to ensure an even and reproducible removal force; and re-measuring the print density.
• the ratio of the print density after removal of the tape to the print density before application of the tape is then expressed as a percentage value termed the "toner adhesion".
• the starch used was a mill-cooked potato-based starch.
• the same product benefits were obtained.
• the procedure was generally as described in Example 3, except that the refining conditions were different, the solids content of the treatment composition was 10% and precipitated calcium carbonate was used as the filler rather than ureaformaldehyde resin synthetic pigment.
• the final paper had a basis weight of 101 g m -2 , topside and wireside roughnesses of 195 and 132 ml min -1 respectively, a 60 second Cobb value of 27 and a filler content of about 11%.
• the paper according to the invention performed better than the control paper in terms of colour appearance, colour print bleed and ink drying time.
• the control paper was slightly better in terms of colour brightness and intensity, probably because the control paper was very hard sized, but these marginal benefits are completely outweighed by the severe print bleed, the mottled appearance and the high drying time of the control paper.
• Example 3 Each treatment composition was applied to respective sheets of test paper as used in Example 2, and then dried and calendered, also as described in Example 2. The various sheets, together with a control sheet which was conventionally starch-sized, were then printed and evaluated as described in Example 3.
• papers according to the invention showed improved colour print bleed and monochrome optical density performance, and much better toner adhesion compared with the control paper.
• the paper according to the invention had improved colour brightness and colour print bleed, a shorter ink drying time and much improved toner adhesion, compared with the control paper.
• the total dry pick up of the composition was ca. 4 g m -2 (4%) and the 60 second Cobb value was 24.
• the Bendsten roughness of both surfaces of the paper was in the range 50 - 60 ml min -1 .
• the paper according to the invention had improved colour appearance, improved colour print bleed and much improved toner adhesion compared with the control paper.
• compositions were each applied to a relatively rough flecked 100 g m -2 decorative text and cover paper during its production on a full-size papermachine.
• the resulting papers were tested as in Example 7, and the results obtained were as follows:
• the paper according to the invention had improved colour print bleed and much improved toner adhesion compared with the control paper. Accurate comparison of properties such as appearance (mottle) and colour brightness was hindered by the decorative flecked appearance of the paper.
• the pigment used was calcium carbonate ("Hydrocarb* 90", supplied by Croxton & Garry, Dorking, England) and was present in the treatment composition in an amount of 5% calculated as dry weight of pigment to aggregate dry weight of starch, hydrophilic polymer and hydrophobic polymer.
• This treatment composition and general procedure were otherwise as in Example 3. Additionally, paper was produced using the same treatment composition without pigment and, separately, with a 100% starch treatment composition.
• both papers according to the invention had improved colour appearance, improved colour print bleed, shorter ink drying time and much improved toner adhesion compared with the control paper.
• the final paper had a 60 second Cobb value of 26, and topside and wireside smoothness values of 60 ml min -1 and 50 ml min -1 respectively (Bendsten).
• the dry pick up of the treatment composition was ca. 4%, i.e. ca. 2 g m -2 per side.

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• 1995
  • 1995-06-07 GB GBGB9511482.3A patent/GB9511482D0/en active Pending
• 1996
  • 1996-06-03 CA CA002178013A patent/CA2178013A1/en not_active Abandoned
  • 1996-06-04 ZA ZA964596A patent/ZA964596B/xx unknown
  • 1996-06-04 AU AU54738/96A patent/AU697858B2/en not_active Ceased
  • 1996-06-05 AT AT96304148T patent/ATE195690T1/de not_active IP Right Cessation
  • 1996-06-05 PT PT96304148T patent/PT747235E/pt unknown
  • 1996-06-05 EP EP96304148A patent/EP0747235B1/de not_active Expired - Lifetime
  • 1996-06-05 DE DE69609899T patent/DE69609899T2/de not_active Expired - Fee Related
  • 1996-06-05 ES ES96304148T patent/ES2149429T3/es not_active Expired - Lifetime
  • 1996-06-06 MY MYPI96002278A patent/MY114712A/en unknown
  • 1996-06-07 SG SG1996010014A patent/SG47150A1/en unknown
  • 1996-06-07 CN CN96106612A patent/CN1086168C/zh not_active Expired - Fee Related

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