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
  • B41M5/10—Duplicating or marking methods; Sheet materials for use therein by using carbon paper or the like

Definitions

• the invention relates to an aqueous coating of carbonless paper consisting of a porous inorganic matrix, an elasticizing organic polymer and the color paste enclosed in the pores.
• the coating of carbon paper consisted of compositions containing waxes and coloring pigments such as carbon black.
• the main disadvantage of these coatings is that they tend to smear during handling because of the soft wax coating, and the copy is poorly adherent. Furthermore, only a small number of breakthroughs are possible with such wax coatings.
• a coating of carbonless paper based on aqueous dispersions is claimed in DE-AS 1 237 145 (CA-A 771,594).
• an aqueous dispersion the continuous phase of which consists of the synthetic resin (polyvinyl alcohol) dissolved in water, and the dispersed phase of which contains the dye dispersed in oil, is applied to the carrier material and dried by heating.
• the resin gels into a microporous sponge, the pores of which are filled with the dye dispersion.
• organic or inorganic crosslinking agents such as N-methylolurea or chromium compounds can also be added in this process.
• the disadvantage of this procedure is the poor storage stability of the dye dispersion in the presence of a crosslinking agent. If one works in this process without the addition of crosslinking agent or if only a moderately reactive crosslinking agent is used, a satisfactory formation of the sponge structure within a reasonable temperature range cannot be achieved.
• the storage stability of the carbonless paper is unsatisfactory. Post-crosslinking and migration phenomena occur, which lead to a change in the write-through behavior when storing the coated copy paper.
• the coating quality in this process depends heavily on the temperature control during curing. If the sponge structure is not formed uniformly, the writing paste sweats into the intermediate layer or onto the surface of the copy paper. The consequences are a lack of liability for the copy and an uneven, bold typeface, or soiling when handling and smearing the copy. Especially when the glass transition temperature of the polymer to be crosslinked is high compared to the specified process temperature, there are difficulties in film formation. The consequences of this are cracking, poor adhesion, poor mechanical resistance and poor reproducibility.
• this problem could be solved by producing a porous inorganic matrix during the coating of the copy paper, in which the writing paste can be incorporated during film formation, the inorganic matrix being elasticized by the use of an organic water-soluble or water-dispersible polymer in order to provide a flexible, to obtain a mechanically stable writing layer that adheres well to the substrate.
• the invention relates to a coating for carbonless paper, which is applied to conventional carrier materials, characterized in that the coating consists of a porous inorganic matrix of Zr4+ polycondensate or ZrO2 ⁇ Al2O3 gel, which by adding film-forming organic polymer is elasticized, and in the pores of which the oil-dispersed dye is enclosed.
• the invention further relates to a process for the production of this coating for carbonless paper, characterized in that the organic polymer is initially introduced in 10 to 50% by weight aqueous solution or dispersion, and a pH of 8 to 9 is adjusted by adding concentrated ammonia , after admixing the color paste, a zirconium compound in 5 to 20% strength aqueous solution is added, and after application of the coating composition to the support, it is dried at a temperature of 40 to 160.degree.
• the porous inorganic matrix is made up of polycondensates of water-soluble Zr4+ compounds or water-soluble Al-Zr mixed oxide compounds.
• Water-soluble Zr4+ compounds are preferably used.
• Ammonium zirconium carbonate is particularly preferred. These compounds are characterized in particular by the fact that they form low molecular weight associates with NH 3 in the alkaline, which have excellent storage stability. Only when the coating composition is applied while the ammonia is evaporated, these associates polycondense to form so-called zirconium oxide quaternary ZrO2 ⁇ xH2O or ZrO2-Al2O3 gels (Gmelin 42 (1958), pp. 251 and 444) to form the microporous inorganic matrix.
• these zirconium or Al-Zr compounds are added to the alkaline mixture of the other coating components.
• concentration of the aqueous solution of the Zr compounds or Zr-Al compounds is preferably 5 to 20% by weight.
• this microporous inorganic matrix per se is not suitable for use in copy paper coating. Additional film-forming organic polymers are therefore added, which make the inorganic matrix flexible, mechanically resistant and improve the adhesion of the microporous matrix to the carrier material.
• Water-soluble or alkali-soluble polymers or water-dispersible polymers are particularly suitable for the elasticization of the inorganic matrix; water- or alkali-soluble polymers are preferably used. Alkali-soluble polymers are particularly preferred.
• alkali-soluble polymers are polyacrylates and polyvinyl acetates which contain 5 to 15% by weight of comonomers containing carboxyl groups, such as (meth) acrylic, itacon, croton, maleic or fumaric acid units.
• comonomers containing carboxyl groups such as (meth) acrylic, itacon, croton, maleic or fumaric acid units.
• alkali-soluble polyesters or alkyds is also conceivable.
• Suitable water-soluble polymers are polyvinyl alcohols, celluloses (hydroxyethyl, methyl, carboxymethyl cellulose), polyacrylamides, polyacrylic acids, polyvinyl pyrolidones.
• water-dispersible polymers are polyvinyl acetates, vinyl acetate / ethylene copolymers, vinyl acetate / ethylene / vinyl chloride mixed polymers, polyacrylates, polyurethanes and SBR latices.
• the polymers used can also be crosslinked to improve the water resistance.
• the crosslinkers used for this should be water-miscible or water-dispersible. They should be reactive in the intended processing temperature range and have sufficient pot lives. Polyaziridines, di- or polyaldehydes (glyoxal), melamine crosslinkers, urea crosslinkers, blocked isocyanates or polyepoxides are preferably used as crosslinkers.
• the amount of crosslinking agent should be chosen so that the desired improvement in properties is achieved without the necessary flexibility of the coating suffering.
• the crosslinkers are preferably used in an amount of 5 to 40% by weight, particularly preferably in an amount of 5 to 20% by weight, based on the polymer.
• the weight ratio of crosslinked or uncrosslinked polymer to the inorganic matrix in the copy paper coating is 1: 1 to 5: 1, preferably 1: 1 to 3: 1, the proportion of the binder (inorganic matrix and organic polymer) in the coating being 20 to 80% by weight .% is.
• the copy paper coating can optionally be modified by further additives.
• the porous matrix can be made more flexible by adding plasticizers to the polymers.
• the plasticizers must be compatible with the polymers used and, if possible, not be miscible with the writing paste. Quantities and types of plasticizers are state of the art and described in the specialist literature (cf. Modern Plastics Encyclopedia 1981-1982, pp. 710-719).
• Co-solvents are water-soluble or partially water-soluble organic solvents such as alcohols, glycols, glycol ethers, esters, ketones, amino alcohols, lactones.
• the amounts added are 1 to 50% by weight, preferably 3 to 25% by weight, based on the aqueous coating composition.
• All common organic or inorganic pigments can be used as dyes in the copy paper coating according to the invention.
• Examples include phthalocyanine blue, permanent ruby, carbon black and titanium dioxide.
• the pigments are used as a paste dispersed in oil (e.g. paraffin oil).
• oil e.g. paraffin oil
• the weight ratio of oil: pigment is approximately 1: 1 to 2: 1.
• the proportion of color paste in the coating is 20 to 80% by weight.
• the pigment paste is produced in a conventional manner.
• the pigment is dispersed in the oil by rubbing on a roller.
• wetting and dispersing agents can also be used in order to make the grinding process more economical and to fully utilize the color strength potential of the sometimes very expensive organic pigments and to obtain sufficiently stable color pastes.
• Ionic and non-ionic surfactants are mainly used as wetting agents, while commercially available preparations are used as dispersing agents. In type and quantity in accordance with the manufacturer's instructions.
• the organic polymer is introduced in 10 to 50% by weight solution or dispersion, and, if appropriate, by adding water or a mixture of water and water-miscible organic solvents (for example ethanol), a content of 10 to 20% by weight .% set.
• water or a mixture of water and water-miscible organic solvents for example ethanol
• concentrated Ammonia is adjusted to a pH of 8 to 9.
• the batch can be slightly warmed when using polymer dispersions.
• the color paste is mixed in and dispersed.
• the zirconium compound is mixed in 5 to 20% solution.
• the corresponding amount of crosslinking agent is added in 10 to 30% by weight aqueous dispersion as the last component, if appropriate immediately before application.
• a pH of 8 to 10 is set in a preferred embodiment after the polycondensation of the zirconium compound by adding neutralizing agent.
• Volatile bases are suitable as neutralizing agents, for example ammonia, organic amines (methyl, dimethyl, ethyl, diethylamine), amino alcohols (aminoethanol, aminopropanol) or N-alkylamino alcohols (dimethylaminoethanol).
• zirconium compound, organic polymer and color paste are chosen so that the weight ratios mentioned above are established in the copy paper coating.
• the coating composition is applied to the carrier materials customary for this purpose, such as paper, plastic films made of polyester or non-woven fabrics.
• the application is carried out using known methods, such as, for example, spreading by doctor blade, roller application or casting in a layer thickness of 12 to 100 ⁇ m wet film thickness.
• the coating After application, the coating is dried in a hot air stream or by irradiation with infrared light at a temperature of 40 to 160 ° C.
• the copy paper coating is overcoated with itself, in a dye-free composition, in the manner just described.
• Example 1 As in Example 1. Instead of paraffin oil, 20 parts of chlorinated paraffin 40 (Hoechst AG) and 15 parts of heliogen blue D 70 82 T are used. (Density difference between paraffin oil and chlorinated paraffin).
• the mixture is subsequently dispersed again on a three-roller.
• Matrix formers as a top coat to improve the mechanical and writing properties were tested with the following formulation 50 Parts of Vinnapas® Dispersion LL 531 (Wacker-Chemie), 10% in water with 10% ethoxypropanol 10th Parts AZC-Sol. (20%, MEL)
• Matrix former 40 Parts of Vinnapas® Dispersion LL 533, 20% in water, pH 9 0.09 Parts Fluorad® FC 129 (3M Company) 25th Share color paste from example 3
• the coating of the examples and comparative examples was applied in a layer thickness of 50 ⁇ m wet film thickness to polyester film as the carrier material and dried at 80 to 120 ° C.
• the carbonless paper was then tested for cracking, font size, regularity of the font, number of easily legible copies, soiling of the copy and soiling of the hands.

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• 1988
  • 1988-02-19 DE DE3805265A patent/DE3805265A1/de not_active Withdrawn
• 1989
  • 1989-01-11 US US07/296,205 patent/US4933012A/en not_active Expired - Fee Related
  • 1989-02-17 JP JP1036439A patent/JPH01249384A/ja active Granted
  • 1989-02-17 EP EP19890102710 patent/EP0329150A3/fr not_active Withdrawn

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