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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/36—Polyalkenyalcohols; Polyalkenylethers; Polyalkenylesters
• • 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
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
• • 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
  • D21H19/10—Coatings without pigments
  • D21H19/12—Coatings without pigments applied as a solution using water as the only solvent, e.g. in the presence of acid or alkaline compounds
• • 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
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/14—Layer or component removable to expose adhesive
  • Y10T428/1476—Release layer
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/28—Web or sheet containing structurally defined element or component and having an adhesive outermost layer
  • Y10T428/2839—Web or sheet containing structurally defined element or component and having an adhesive outermost layer with release or antistick coating

Definitions

• the object of the invention is coated base paper particularly suitable as base paper or release paper for labels, and a method for manufacturing coated base paper, wherein a barrier, i.e., protective layer is applicated to coated paper based on cellulose fibres.
• Base papers also known as release paper or backing papers, are used in the manufacture of label laminates and self-adhesive labels, and increasingly, also as packaging material for adhesive materials.
• base paper or release paper either is glassine-type transparent super-calendered and surface sized paper, or paper usually blade coated with pigments containing kaolin, for example, fine paper super-calendered as to be as impermeable as possible.
• Typical known prior- art laminate structures of pressure-sensitive labels are shown schematically in Figure 1 appended.
• base paper 10 has been applicated with a release coating 20, most frequently comprising silicone.
• a pressure-sensitive glue layer 30 has been applicated to the release coating 20 containing silicone, and a surface paper 40 forming a label has been affixed to the adhesive layer 30.
• the silicone layer applicated to the base paper must be smooth and lacking holes, as the surface paper of the label then will detach in a smooth manner as desired, from the surface of the base paper.
• the base paper cannot have holes, wrinkles, dust or unevenness.
• the surface of the base paper should be sufficiently sealed to prevent the silicone from penetrating into the base paper. Neither may the base paper chemically affect the catalytic hardening of the silicone. If holes are present in the base paper, adhesive from the adhesive layer may penetrate the silicone layer to the base paper, resulting in fissures and breaks in the web of the litter path and of the label laminate during subsequent processing.
• the silicone is applicated onto the base paper in a thickness of 1 to 1.25 g/m 2 and cured at approximately 140 °C.
• Silicones being expensive, efforts are to applicate the silicone in as thin layers as possible, but on the other hand, due to the good detachment characteristics, nonetheless is necessary to manufacture the silicone layer to have sufficient thickness so as to in advance prevent the appearance of possible problems and breaks because of holes, porosity, and surface unevenness often present in fine paper.
• the surface of the base paper should be as impermeable and smooth as possible.
• patent JP 171 600/93 the coating of paper on both sides with polyvinyl alcohol is described, followed by treatment with pressurized steam and calendering.
• polyvinyl alcohol is commonly used as protective colloid in coating pastes. Particularly, polyvinyl alcohol grades having low molecular weight are suitable for coating pastes comprising kaolin-containing pigment mixtures and the like. Polyvinyl alcohol is also used as primary or auxiliary binding agent in coating and surface sizing compositions and as carriers for excipients such as fluorescent brighteners.
• the drying of polyvinyl alcohol as a separate layer on a web is known to be difficult and energy consuming, as a leathery surface easily appears on the polyvinyl alcohol from where the water it contains is difficult to remove, resulting in the surface remaining uneven.
• An object of the invention is coated impermeable base paper, based on chemical pulp.
• a further object of the invention is a method for the manufacturing of coated impermeable base paper, based on chemical pulp.
• an object of the invention is the use of coated impermeable base paper, based on chemical pulp, as base paper and release paper for labels.
• one or several thin barrier layers are applicated onto pigment-coated paper manufactured from cellulose fibres, preferably primarily, particularly preferably in excess of 50%, from chemical pulp.
• the thickness of the layer is defined through measurement of the layer's grammage (g/m 2 ) by weighing the base paper and coated paper, or calculating by squares metres used and the flow of barrier chemical (g/s/m 2 /s).
• the paper is fine paper pigment-coated as known in the art, for whose coating has been used pigment paste comprising kaolin or carbonate, preferably kaolin paste, having a binding agent selected from the group comprising styren-butadiene latex, polyvinyl alcohol and other common binding agents used in the art.
• one layer of an aqueous solution comprising a barrier chemical is applicated, using a method non-contacting the web known per- se, which method is selected from the group comprising a curtain coating method and a spray method performed by spraying.
• the barrier chemical is selected from the group comprising polyvinyl alcohol, acrylate-based barrier latexes of which as examples may be mentioned the Rebarco ® series of the company Raisio Chemicals Oy, and their mixtures.
• polyvinyl alcohol is used having a short chain, the viscosity (mPas) and degree of hydrolysis (mol-%) varying in the ranges 3 to 98 - 15 to 99.
• the barrier chemical is applicated as an aqueous solution having a barrier-chemical content of 3 to 50 weight-%, preferably 3 to 25 weight-%, and particularly preferably 3 to 5 weight-%, so that the solution being applicated has a viscosity of at most 100 cP, preferably at most 50 cP.
• acrylate latexes as barrier chemicals, these may also contain fillers, pigments, styrene-butadiene latexes and other conventional binding agents.
• the barrier chemical is applicated so as to have an amount of it preferably 0.5 to 3 g/m in the base paper.
• the application of the barrier layer is performed as on-line coating.
• the barrier layer After the application of the barrier layer, drying is carried out using non- contacting drying techniques, with methods known in the art, such as IR or fluid bed drying methods. After drying, optional super calendaring may be performed. Already as such, the barrier layer according to the invention is impermeable to an extent that super calendering is not necessarily needed. In spray application and curtain coating methods, optionally pigments, surface-tension regulators, drying agents, anti-foaming agents and other excipients known in the art may be added to the barrier layer.
• a non-contacting method such as spray or curtain coating method is used for applicating the barrier layer, by which methods an impermeable homogenous surface is provided. As no device having parts contacting the web is used in these methods, they cause no breaks.
• base paper having an exceptionally impermeable, homogenous and smooth surface lacking holes can be manufactured.
• Siliconizing may be performed by any methods known in prior art, using any silicone or silicone emulsions known in the art from labels and release papers.
• the amount of fibre material in the base paper can be reduced, as also the amount of binding agent in the coating paste, and the amount of actual coating paste can be reduced by up to 20 %, compared with conventional ones.
• base papers of lighter grammage but being of at least as good quality as base papers known in prior art, and having a bulk similar to or even higher than those. Calendering can be made lighter and standard thickness is achievable with lighter paper. Using the solution according to the invention, it is also possible to achieve significant reductions in the consumption of material.
• Non-calendered paper Simkraft MF Special ® having a grammage of 85 g/m 2 and blade coating of 12.5 g/m 2 was coated with a thin layer of polyvinyl alcohol by spray coating using a Helicoater device.
• Sample 1 was a reference sample not coated.
• polyvinyl alcohol Mowiol ® having a degree of hydrolysis of 10 - 98, solid content of 5 %, viscosity of 64 cP, and the amount applicated being 1 g/m 2 was used.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Paper (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (7)

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Family Cites Families (45)

• 2003
  • 2003-06-30 FI FI20030976A patent/FI20030976L/sv unknown
• 2004
  • 2004-05-25 CA CA002531153A patent/CA2531153A1/en not_active Abandoned
  • 2004-05-25 CN CNA2004800184230A patent/CN1813106A/zh active Pending
  • 2004-05-25 WO PCT/FI2004/000317 patent/WO2005001201A1/en active Application Filing
  • 2004-05-25 JP JP2006516223A patent/JP2007514868A/ja active Pending
  • 2004-05-25 EP EP04734697A patent/EP1639200A1/en not_active Withdrawn
  • 2004-05-25 US US10/563,102 patent/US20060231226A1/en not_active Abandoned

Non-Patent Citations (1)

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