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
  • D21H19/80—Paper comprising more than one coating
  • D21H19/82—Paper comprising more than one coating superposed
• • 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
  • D21H19/40—Coatings with pigments characterised by the pigments siliceous, e.g. clays
• • 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
  • D21H19/82—Paper comprising more than one coating superposed
  • D21H19/826—Paper comprising more than one coating superposed two superposed coatings, the first applied being pigmented and the second applied being non-pigmented

Definitions

• the invention relates to a security paper for the production of value documents, such as banknotes, passports, identity cards or the like, which is provided with an impregnation or coating, which ensures an increased circulation capability, and to processes for producing such a security paper.
• Banknotes are usually made of so-called security papers, which are made of cotton fibers and have special security features, such as an at least partially introduced into the paper security thread and a watermark.
• the circulation period of a banknote depends on the demand. Certain denominations are preferably used commercially and thus have a lower cycle time due to the increased exposure to environmental influences.
• the main cause of the limited circulation time of banknotes is early pollution. Since banknote paper is very porous, it has a large surface area and a high surface roughness. Although the protrusions and cavities resulting therefrom are in orders of magnitude which can no longer be resolved by the human eye, they nevertheless offer ideal conditions for dirt deposits in comparison to a smooth surface.
• a particularly serious problem is the sensitivity of banknote paper, and more generally of paper, to oil and water. Because of the lack of oil and water repellant properties of untreated paper Paper Paper quickly penetrates oil and water into the material. Water softens the paper, thereby reducing its mechanical stability, which can lead to surface abrasion or cracking of the wet spots. Soiling of fats and oils has the additional disadvantage that they form ugly "grease stains" in the paper, which are practically indelible. The affinity of the lipophilic substances for the paper is increased by the equipment of the paper with Masseleimen (resin glues, AKD glues).
• WO 96/28610 From the WO 96/28610 is a method for producing security paper is known in which the paper is glued and then provided on at least one side with a coating that gives the paper properties such as improved resistance to contamination, good adhesion properties for printing ink, no significant effect on the "grip" of the paper, resistance to picking up optical brighteners, and good visibility of security features because of the transparency of the Coating.
• the coating is based on polyurethane. Extenders may be included in the polyurethane, for example, polyacrylate, styrene-acrylic copolymers, acrylated vinyl acetate, vinyl chloride-ethylene copolymers, or vinyl acetate copolymers.
• a security paper which is provided on at least one surface with a coating consisting of a composition containing an acrylate system as the exclusive binder and no fillers.
• the coating makes the security paper dirt repellent and thereby increases the useful life of the security paper, or the circulation time of a banknote, the coating the typical properties of the security paper, such as "grip", printability, sound, color, not or at least not noticeably changed.
• US-A-5,660,919 discloses a coating for security paper such as banknotes which has good printability properties and increases wear resistance.
• the coating consists of at least one polyurethane binder and at least one filler.
• WO 03/087471 A1 discloses a water-dispersible sizing agent for cellulosic materials having repeating units consisting of a polyamine having at least three nitrogen atoms in each monomer unit, the amino groups being partially or fully substituted with a group reactive with cellulose and having an oleophobic and hydrophobic fluorinated group ,
• a suitability of sizing for security papers such as banknote paper, which preferably consists of cotton fibers, is not disclosed.
• the reaction of the cellulose-reactive groups and the paper also entails the risk of changing the paper's properties, for example changing the "feel" of the paper.
• WO 00/43438 discloses perfluoroalkyl-substituted polyamino acids consisting of oligomers / copolymers of aliphatic diaminocarboxylic acids and having from 3 to 10 carbon atoms and containing at least two perfluoroalkyl groups bonded to the nitrogen atoms via a linking group.
• the previously known paper coating compositions are either unsatisfactory in terms of their protection against grease, oils and / or water, or they are more suitable for materials such as textiles, carpets, cardboard, packaging for fatty foods, possibly for the coating of normal printing paper.
• Perfluorinated compounds which are suitable for coating security papers with which it is applied arrives that its typical properties such as grip, sound, color, etc. remain unchanged, have not been revealed.
• the object of the present invention is therefore to provide a security paper which has improved dirt-repellent properties and, as a result, a long service life, while retaining the security-typical properties.
• fluorocarbon resins surface-active fluoroaliphatic polymeric esters and fluorine-containing copolymers based on acrylate are used for the protection of banknotes and other security papers against lipophilic and aqueous substances.
• the fluorocarbon resins are perfluorinated, alkyl-substituted, ie perfluoroalkyl-substituted, carboxylic acids or their salts, preferably aliphatic N, N-di-perfluoroalkyl-substituted monoamino-monocarboxylic acids, or salts thereof.
• M is hydrogen or a charge-balancing cation.
• the perfluoroalkyl groups are linear or branched, preferably linear.
• the number of carbon atoms of the perfluoroalkyl groups is preferably 1 to 16, more preferably 6 to 12.
• the perfluoroalkyl groups bonded to a nitrogen atom may be the same or different.
• m n.
• the perfluoroalkyl-substituted monoamino-monocarboxylic acids may have a defined molecular weight, but usually have a more or less broad distribution of the molecular weight, d. h.,
• the fluorocarbon resins are mixtures of compounds having different perfluoroalkyl groups.
• the cation required for charge equalization is preferably ammonium, an alkali metal, preferably lithium, sodium, potassium, or an alkaline earth metal, preferably magnesium, calcium, or aluminum.
• N, N-di-perfluoroalkyl-substituted monoamino-monocarboxylic acids according to the invention are used either as compounds of defined molecular weight or as a mixture of compounds with different molecular weights or as a mixture of compounds of different structure type.
• N, N-di-perfluoroalkyl-substituted monoamino-monocarboxylic acids may also be present in polymerized form.
• Further classes of substances which are used according to the invention for protection against lipophilic substances and aqueous substances are surface-active fluoroaliphatic polymeric esters and fluorine-containing copolymers based on acrylate.
• the security paper is provided with at least one compound of at least one of the substance classes fluorocarbon resins, surface-active fluoroaliphatic polymeric esters and fluorine-containing copolymers based on acrylate.
• the fluorocarbon resins are suitable for impregnating sized and unsized substrates.
• impregnation does not only mean the penetration or impregnation of the substrate, but also only a coating of the substrate. Whether a resin is present as a coating and / or penetrates into the substrate, depends on the nature of the resin and the substrate and can be controlled as needed.
• Fluorocarbon resins may also be used together, i. H. in admixture, with a sizing agent.
• dirt-repellent coatings as in EP 1 099 024 B1 which contain an acrylate system as exclusive binder and no fillers.
• Other dirt-repellent coatings that can be applied additionally are the in WO 96/28610 disclosed polyurethane coatings.
• the additional coatings are not limited to those mentioned above.
• the application of the further coating agent can also be carried out simultaneously with the equipment with the fluorocarbon resin.
• the further coating agent is first applied and then impregnated with the fluorocarbon resin.
• the security paper After the security paper has been provided with the fluorocarbon resin and, if appropriate, sizing agents and optionally further coating agents, the security paper can be printed in the usual way.
• the fluorocarbon resin-impregnated paper In general, in printing the fluorocarbon resin-impregnated paper, despite the large reduction in surface energy by the fluorocarbon resins, there is no wetting disturbance and no deterioration in the adhesiveness of the printing inks. In order to exclude such disturbances with certainty, one can choose the above-mentioned two-stage application, which is first impregnated with fluorocarbon resin and then coated with a good printable composition, for example with the acrylate according to EP 1099024 or with the polyurethane coating according to WO 96/28610 ,
• the security paper with or without a debris-repellent coating, is first printed and then impregnated with the fluorocarbon resin.
• the fluorocarbon resin can be used alone or in combination with other coating agents.
• the printed security paper is first coated with an acrylate coating or other overprint security paper such as banknotes usual formulation (as in the WO 00/00697 ), and then applied the fluorocarbon resin.
• the substance classes fluorocarbon resins and / or surface-active, fluoroaliphatic polymeric esters and / or fluorine-containing copolymers based on acrylate used according to the invention are preferably used in the form of their aqueous dispersions.
• the fluorine-containing copolymers based on acrylate usually form emulsions. Also conceivable are solvent-based systems.
• the aqueous fluorocarbon resin dispersions for application have a solids content of from 15 to 22% by weight, preferably from 18 to 19% by weight.
• the fluorocarbon resins are used in combination with other dirt-repellent components, it is preferred to mix the fluorocarbon resin dispersion of a dispersion of the further component.
• the mixing ratios can vary within a very wide range.
• the mixing ratio of fluorocarbon resin / further components is preferably at least 1/25, more preferably from 1/5 to 1/20.
• the solids content of the mixed dispersions is preferably 30-50%.
• the fluorocarbon resins, the surface-active fluoroaliphatic polymeric esters and the fluorine-containing copolymers based on acrylate in the mixture and together used with another coating agent, the mixing ratios given above for the fluorocarbon resin alone with the other coating component for the sum of fluorocarbon resin, surface active fluoroaliphatic polymeric ester and fluorine-containing copolymer compound based on acrylate apply.
• the application of the fluorocarbon resins to the paper is preferably done on both sides, but also a one-sided application is possible.
• the application amount of fluorocarbon resin (dry) per side is preferably 1.0 to 4.0 g / m 2 , more preferably 2.0 to 3.5 g / m 2 .
• the solids of the fluorocarbon resin is preferably 0.5% based on the paper pulp (g / m 2 ).
• the application of the fluorocarbon resins is carried out on the finished unprinted or printed security paper, or also in the wet-end area of the paper machine, or in the dipping bath or the size press of the paper machine.
• the fluorocarbon resin may be used together with other coating agents, wherein the fluorocarbon resin dispersions may be mixed with the dispersions of the further coating agents, or wherein the fluorocarbon resin dispersions and the dispersions of the further coating agents may be applied separately.
• intermediate drying is recommended.
• the dispersions can also be applied at various stages of the security paper making process, for example, coating with styrene acrylate can be done in the size press, while impregnation with fluorocarbon resin takes place after printing.
• impregnations for example impregnation with fluorocarbon resin in the wet-end area of the paper machine, then a coating with further coating agent in the size press, followed by printing the security paper, finally re-application of a fluorocarbon resin, optionally in admixture with another coating agent.
• fluorocarbon resin in the wet-end area of the paper machine
• a coating with further coating agent in the size press followed by printing the security paper
• re-application of a fluorocarbon resin optionally in admixture with another coating agent.
• the unsized or glued or optionally pretreated security paper with dilute (preferably ⁇ 0.5% solids based on pulp) aqueous dispersions of fluorocarbon resins impregnated may also be blended into the dispersion of another coating agent, or after impregnation with the fluorocarbon resin in a second step, the coating made with the further coating agent. Drying is recommended between the application steps. Other coatings can be made off-line.
• aqueous dilute fluorocarbon resin dispersions are used alone or together with a dispersion of a further coating composition.
• a stepwise application of a coating agent, followed by application of a fluorocarbon resin dispersion, is also advantageous.
• the fluorocarbon resin dispersion can be added to coating agents such as those conventionally used for coating already printed paper substrates, e.g. As banknote substrates, are used and, for example in the WO 00/00697 are described.
• a dilute fluorocarbon resin dispersion alone may be used, or a stepwise application of a coating agent and then a fluorocarbon resin dispersion may be performed.
• the additional coating agents to which the fluorocarbon resins are blended, or which are applied separately in addition to the fluorocarbon resins are preferably acrylate systems as described in U.S. Pat EP 1099024 ie, acrylate homopolymers and / or copolymers and / or polymer blends. Preference is given to styrene-acrylates.
• Advantageous additional coating agents are also polyurethane systems.
• the coating compositions may contain further additives, for example Extenders, contained in amounts that do not interfere with the properties of the coating.
• An aqueous dispersion of a fluorocarbon resin (Ciba Lodyne 2000, Ciba) is admixed with an aqueous dispersion of a styrene-acrylate varnish (Primal P-322 AF, solids content 50%, Rohm and Haas).
• the mixing ratio of fluorocarbon resin / styrene-acrylate lacquer is 2/25.
• the mixed dispersion is applied on both sides to a standard cotton substrate with polyvinyl alcohol sizing in a flexographic printing process. The order quantity is approx. 2.5 g / m 2 (dry) per side. Subsequently, the cotton substrate is dried and subjected to the usual banknote printing operations.
• aqueous dispersion of a fluorocarbon resin (Ciba Lodyne 2000, Ciba) is now applied on both sides of the coated substrate in a flexographic printing process.
• the order quantity is 1.0 g / m 2 (dry) per side.
• the substrate is dried again.
• a cotton substrate with polyvinyl alcohol sizing instead of the cotton substrate with polyvinyl alcohol sizing, a cotton substrate with styrene acrylate coating or a cotton substrate, which has both a polyvinyl alcohol sizing and a styrene-acrylate coating can be used.
• the inventively impregnated cotton substrates show a significant reduction in the tendency to fouling, in particular a significantly reduced tendency to take greasy and oily substances into the interior of the substrate. This also applies after multiple buckling of the substrate. The observed effect is essentially due to the reduction of the surface energy of the impregnated substrates by the fluorocarbon resins.
• paraffin oil wets the standard banknote paper and penetrates into the substrate. After removing the drop of paraffin oil through an absorbent cloth, an oil stain remains.
• the paraffin oil wets the banknote paper and penetrates partially, especially at kinks of the substrate, in this one. Again, however, remains after removing the drop through an absorbent cloth a clearly visible oil stain back.
• the application according to the invention of the fluorocarbon resins reduces the surface energy of the coated substrates and also creates a smooth surface, so that contaminants are repelled and also find no mechanical support on the surface.
• the surface energy is increased so that the contact angle ⁇ of oily liquids is greater than 90 ° ( ⁇ > 90 °).
• the properties of the paper are not changed by the impregnation, which is of the utmost importance in the field of security papers.
• Security papers, especially banknotes are not only recognizable by their security features, but to a certain extent by their special paper as real. In addition, they often contain watermarks and other imprints that must not be changed by protective treatments of the paper, so as not to disturb the overall impression.
• the impregnation composition can be used not only for protection against lipophilic and aqueous substances, but at the same time for the application of security features.
• at least one substance is brought visually into the dispersion of the fluorocarbon resin and / or mechanically detectable physical property, for example luminescent substances.
• Such substances are known to the person skilled in the art.
• both surfaces of the paper substrate are preferably fully impregnated with the aqueous dispersion of the fluorocarbon resin, but it is also possible to carry out the impregnation only on one surface and / or only in partial areas of the surface.
• the non-impregnated areas may optionally be protected in other ways.
• the impregnation according to the invention is particularly suitable for paper substrates made from fibers of annual plants, in particular cotton fibers, as are preferably used in the field of security papers.
• the application is not limited to these fibers, and papers made of cellulose fibers and papers which are at least partially made of synthetic fibers can be advantageously impregnated.
• the security papers according to the invention are used for the production of ID cards or passports, the usual lamination with plastic films may optionally be dispensed with, since the paper is adequately protected against contamination by the impregnation according to the invention.
• impregnation with fluorocarbon resins protects the impregnated paper not only against aqueous and oily soils, but also gives the impregnated paper a better general moisture resistance, so that the paper at high humidities, eg. B. in tropical areas, less prone to "limp". If it is desired to improve climate sensitivity, it is advisable to use impregnation with or instead of wet-end sizing Make paper machine. This also improves the mechanical strength of the paper.
• impregnation with fluorocarbon resins is the reduction of the surface energy of the impregnated security paper, which in turn leads to a reduction in the tendency to fouling.
• the impregnated paper is simultaneously well protected against oily and aqueous soiling, so that the security paper can be used much longer than without the impregnation of the invention.
• the best protection is achieved when the impregnation according to the invention is provided as a surface finish.

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

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Citations (5)

• 2005
  • 2005-11-04 DE DE200510052672 patent/DE102005052672A1/de not_active Withdrawn
• 2006
  • 2006-10-30 EP EP06022667A patent/EP1783273A1/fr not_active Withdrawn

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