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
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
  • B41M5/42—Intermediate, backcoat, or covering layers

Definitions

• the invention relates to a heat-sensitive recording material having a substrate, a heat-sensitive recording layer containing color formers and color acceptors and a protective layer formed on the recording layer, and to its use as a ticket.
• a heat-sensitive recording sheet of the type mentioned is known from EP-B-0 909 242, corresponding to DE-C-197 13 590 :
• the protective layer of the recording sheet which can be used as a label, receipt or ticket and can be easily printed in the wet offset process, has a pigment content of 20 to 40% by weight, in particular bentonite, as a pigment, while the proportion of binder consists largely of water-insoluble binder in the form of a polymer dispersion and to a lesser extent of an aqueous solution of a polymer.
• This document discloses natural calcium carbonate, precipitated calcium carbonate, silicon dioxide, aluminum oxide and titanium oxide as further pigments in the protective layer.
• the water-insoluble binders are preferably self-crosslinking copolymers of acrylonitrile, methacrylamide and acrylic ester. There are no indications of the possible application of a spot coating in the writing.
• a protective layer is known from EP-A-0 344 705 , in which 0.5 to 3 parts by weight of pigment are present per part by weight of binder.
• Suitable binders for the protective layer include polyvinyl alcohol, carboxymethyl cellulose, starch and starch derivatives and copolymer emulsions of styrene-butadiene, vinyl acetate-ethylene, vinyl acetate-vinyl chloride-ethylene and methacrylate-butadiene.
• Precipitated calcium carbonate, ground calcium carbonate, talc, kaolin, silicon dioxide anhydride, magnesium carbonate, zinc oxide, aluminum oxide and aluminum hydroxide in addition to organic pigments are mentioned as suitable pigments.
• Protective layers containing pigment, which only contain water-soluble binder, are described as examples.
• EP-B-0 373 903 relates to a heat-sensitive recording paper with an internal adhesive strength of 2.5 kg * cm or more, which has a protective layer with a smoothness of at least 500 Bekk seconds, preferably from 700 to 1500 Bekk seconds a fine particle of a styrene-acrylate polymer and an intermediate layer containing a binder is applied.
• Suitable binders for the protective layer are both water-soluble and water-insoluble high polymers with sufficient film-forming capacity.
• Any pigment addition to the protective layer is also disclosed, but there is no indication in the document of the nature of the suitable pigments. Likewise, the document lacks any disclosure regarding spot coating in the sense of this invention.
• tickets and, in particular, tickets usually have imprints applied by means of flexographic or in particular by means of wet offset printing processes, printability on the entire surface of the protective layer at the points where a validator imprint is not provided is a further requirement.
• the new recording material must be characterized by a high level of environmental resistance.
• Another essential aspect of the new recording material must be its cost-effective production method.
• the invention sees its The task is to develop a recording material which, in addition to the range of requirements listed above, also has excellent printability on the entire surface of the protective layer at the points where a validation print is not intended.
• a heat-sensitive recording material having a substrate, a heat-sensitive recording layer containing color formers and color acceptors, a protective layer formed on the recording layer and a full-area, locally limited "printed on the protective layer.
• a heat-sensitive recording paper is already known with a protective layer formed on the recording layer, which is provided with a coating applied in zones.
• the zone-by-zone coating is said to result in increased smudge resistance for stamp imprints.
• the known coating material for the zone-by-layer coating contains binders such as polyvinyl pyrrolidone and / or an acrylic resin solution.
• Typical formulations contain pigments such as silicon dioxide or kaolin in quantities of up to 12% by weight. The use of higher amounts of pigment is discouraged because it is expected that the density of the images produced by means of heat-sensitive recording will decrease to an unacceptable degree and, furthermore, damage to the thermal head will further reduce the image density due to the abrasion of the pigment.
• JP 111 05 422 A which is to be regarded as the closest prior art, also discloses a heat-sensitive recording material, the protective layer of which is provided with a printable, full-surface or locally limited coating.
• the coating with which the protective layer is provided comprises 70 to 95% by weight and, by way of example, 85% by weight of pigments such as, for example, fumed silica.
• the document does not contain any suggestions for the special design of the heat-sensitive recording material, such as the formation of an intermediate layer containing pigment, and certainly not for the special selection of pigments in this intermediate layer.
• the thermal head which triggers the color-forming reaction of the color formers with the color acceptors in the heat-sensitive recording layer causes the wax-like constituents in the recording layer to melt.
• an intermediate layer containing a pigment or a pigment mixture is formed between the heat-sensitive recording layer and the substrate, the pigments of this intermediate layer causing the melt to be absorbed. It is particularly advantageous if the pigment of the intermediate layer of at least 80 cm3 / 100 g, and more preferably of 100 cm, having an oil absorption 3/100 g, determined according to the Japanese standard JIS K 5,101th Calcined kaolin has proven particularly useful due to its large absorption reservoir in the cavities.
• an intermediate layer formed in this way acts as a heat reflection layer, as a result of which the heat sensitivity of the recording material and thus the printing speed in the thermal printer can be increased. Furthermore, such an intermediate layer can make a positive contribution to the leveling of the substrate surface, thus reducing the amount of coating color which is necessarily to be applied for the heat-sensitive recording layer.
• a particularly suitable embodiment of the present invention provides the single-layer formation of the protective layer for economic reasons.
• a coating color as proposed in EP-B-0 909 242 , is well suited for forming the protective layer for the new recording material.
• Such a protective layer combines high environmental resistance with excellent printability in the wet offset process.
• the protective layer is also relatively inexpensive to manufacture and apply in one layer.
• Cyclic urea, methylol urea, polyamide epichlorohydrin resin and ammonium zirconium carbonate are particularly suitable as crosslinking agents for the protective layer.
• An embodiment explained above ensures a heat-sensitive recording material that has good printhead behavior over the entire surface and whose protective layer at the same time has good environmental resistance and excellent printability in the flexographic and wet offset processes.
• the protective layer with a mass per unit area in a range from 1.5 to 6 g / m 2 and in particular between 1.8 and 4 g / m 2 .
• the recording material according to the invention preferably has a backside coating which is applied to the side of the substrate which is opposite to the side provided with the heat-sensitive recording layer.
• a backside coating is proposed, for example, in DE-A-197 48 258 and then serves to improve the printability of the recording sheet on the backside in the offset and flexographic printing process and to improve the blocking effect of the backside against plasticizers, oils and greases.
• application quantities in a range from 1 to 3 g / m 2 and especially between 1.5 and 2.5 g / m 2 have proven to be advantageous.
• the full-surface, locally limited so-called “spot” coating is preferably printed in the form of a rectangle on the edge of the heat-sensitive recording material, which is equipped as a ticket, ie printed and cut.
• spot a greater oil absorption of the pigments in the intermediate layer than the oil absorption of the pigments in the "spot" coating.
• Addition to the pigments having an oil absorption of at least 80 cm 3/100 g are more components of the printing inks prepared water-based for the "spot" coating alcohols such as isopropanol or ethanol as the solvent and, for example, maleate, polyester and acrylate resins as binders, the carboxyl groups of which are saponified with aqueous ammonia or with amines and converted into water-soluble salts.
• the printing inks produced in this way are easy to stamp and the applied stamping ink is smudge-proof after approx. 10 seconds.
• paper is the substrate that has established itself on the market with regard to the good environmental compatibility due to the good recyclability and which is preferred in the sense of the invention.
• the heat-sensitive recording material according to the invention is mainly designed for use as a ticket and here in particular as a ticket.
• the passenger pushes the ticket into a validation machine provided for this purpose so that the validation print is applied to the full-area, locally limited so-called "spot" coating.
• the validator print is dry-wiped so that there is no risk of the passenger getting dirty on the inadequately fixed printing ink.
• the print for control purposes can always be easily deciphered.
• Extensive investigations showed that an ink application with a mass per unit area in a range from 1 to 5 g / m 2 and especially between 2 and 3.5 g / m 2 delivers particularly good results.
• DE-A-199 36 030 provides an overview of authenticity features that can be used individually or in combination , but are not limited to the suggestions made there.
• a paper web made of bleached and ground hardwood and softwood cellulose with a mass per unit area of 67 g / m 2 is added to the substrate on a Fourdrinier paper machine with the addition of conventional admixtures in customary amounts.
• a calcined kaolin as a pigment, styrene-butadiene latex as a binder and starch as a cobinder are applied to the front in addition to an additional intermediate layer of 8 g / m 2 .
• a heat-sensitive recording layer containing color formers and color acceptors and having a mass per unit area of 5.4 g / m 2 is applied to the intermediate layer.
• a protective layer of 2 g / m 2 is applied to the dried recording layer.
• the pigment used is a highly purified, alkaline-processed bentonite with a platelet structure, the inherent adhesion of which enables it to be fixed with little need for binding agents, and the specific surface area of which, in the non-dispersed state, is given as 85 m 2 / g with an area-to-edge ratio which is in powder form Bentonite is in a range between 20 and 50.
• a binder / pigment ratio of 6: 1 and a crosslinking agent / binder ratio of 1: 5 are set.
• the coating slip for the production of the protective layer contains, as further components, a defoamer, stearic acid as a lubricant and various dispersants, on the one hand for the pigment and on the other hand for the lubricant.
• the applied coating slip is dried and the recording sheet produced so far is smoothed by means of a calender, a smoothness of 2200 Bekk seconds being achieved. Then, 8 mm wide strips are printed onto the protective layer as "spot" coatings with a mass per unit area of 2.2 g / m 2 in such a way that the "spot” coating strips are arranged on two opposite outer lines of the ticket when the ticket is cut ,
• the printing ink "DG 9033 (matt lacquer)” offered by GSB-Wahl GmbH, Buchenteich 1, D-73773 Aichwald is used.
• the side of the heat-sensitive recording material according to the invention thus produced which is provided with a protective layer, is checked for its environmental resistance at the points not printed with a "spot" coating and is determined to be very good.
• the validation print is checked after 10 seconds with a damp finger for its smudge resistance; the stamp cannot be blurred.
• Figure 1 shows the schematic structure of the heat-sensitive recording material according to the invention in cross section.
• a back coating (2) is applied to the underside of the substrate (1).
• An intermediate layer (3), a heat-sensitive recording layer (4) and a protective layer (5) are applied to the front of the substrate (1) in the order shown here.
• a full-area, locally limited print job (6) is arranged on the protective layer.
• FIG. 2 shows an example of the heat-sensitive recording material according to the invention, cut to the ticket, in a top view.
• the protective layer (5) which can only be recognized in the top view, the full-area, locally limited print job (6) is applied in the form of a rectangle, the long side of which is arranged parallel to an outer line of the ticket.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Heat Sensitive Colour Forming Recording (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 2001
  • 2001-02-23 DE DE10108982A patent/DE10108982A1/de not_active Withdrawn
• 2002
  • 2002-02-20 AT AT02722100T patent/ATE285335T1/de not_active IP Right Cessation
  • 2002-02-20 DE DE50201836T patent/DE50201836D1/de not_active Expired - Lifetime
  • 2002-02-20 ES ES02722100T patent/ES2235028T3/es not_active Expired - Lifetime
  • 2002-02-20 JP JP2002567546A patent/JP2004520974A/ja active Pending
  • 2002-02-20 WO PCT/EP2002/001756 patent/WO2002068207A1/de active IP Right Grant
  • 2002-02-20 US US10/468,634 patent/US7008902B2/en not_active Expired - Lifetime
  • 2002-02-20 EP EP02722100A patent/EP1363786B1/de not_active Expired - Lifetime

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