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
  • B41M5/382—Contact thermal transfer or sublimation processes
  • B41M5/385—Contact thermal transfer or sublimation processes characterised by the transferable dyes or pigments
• • 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
  • B41M5/382—Contact thermal transfer or sublimation processes
  • B41M5/385—Contact thermal transfer or sublimation processes characterised by the transferable dyes or pigments
  • B41M5/3854—Dyes containing one or more acyclic carbon-to-carbon double bonds, e.g., di- or tri-cyanovinyl, methine
• • 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
  • B41M5/382—Contact thermal transfer or sublimation processes
  • B41M5/385—Contact thermal transfer or sublimation processes characterised by the transferable dyes or pigments
  • B41M5/388—Azo dyes
• • 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
  • B41M5/382—Contact thermal transfer or sublimation processes
  • B41M5/385—Contact thermal transfer or sublimation processes characterised by the transferable dyes or pigments
  • B41M5/39—Dyes containing one or more carbon-to-nitrogen double bonds, e.g. azomethine
• • 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
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/913—Material designed to be responsive to temperature, light, moisture
• • 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
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/914—Transfer or decalcomania

Definitions

• the present invention relates to a new process for the transfer of cationic dyes with cyanine chromophore, in their deprotonated, electrically neutral form from a support to a coated paper.
• a transfer sheet which contains a sublimable dye, optionally together with a binder, on a support is heated with a heating head by means of short heating impulses from the back, the dye subliming or evaporating and transferring it onto a paper serving as the recording medium becomes.
• the main advantage of this method is that it is easy to control the amount of dye to be transferred (and thus the color gradation) by adjusting the energy to be delivered to the heating head.
• the color recording is carried out using the three subtractive primary colors yellow, magenta and cyan (and possibly black).
• the dyes used should have the following properties: - easy sublimability or vaporizability (in general this requirement is most difficult to meet with cyan dyes); - high thermal and photochemical stability as well as resistance to moisture and chemical substances; - have suitable shades for the subtractive color mixture; - have a high molecular absorption coefficient - be easily technically accessible.
• DE-A-2 359 515 proposes a process for dyeing and printing polyacrylonitrile fabric, salts of cationic dyes being transferred from a support to the polyacrylonitrile material under the action of heat.
• the salts are said to be derived from acids, whose pK A value is greater than 3.
• the thermal transfer of these salts leads to insufficient colorations, since a high energy is required to convert these color salts into the gas phase by evaporation or sublimation.
• the dyes are partially decomposed under these conditions.
• EP-A-178 832 describes the thermal transfer of salts of cationic dyes with soft anionic bases on polyester.
• DE-A-2 521 988 teaches the dyeing and printing of polyacrylonitrile by thermal transfer of electroneutral, deprotonated cationic dyes in the presence of an additional indicator dye.
• the presence of an indicator dye is necessary to avoid the formation of faulty prints.
• the thermal transfer takes place at a temperature of 195 ° C.
• many cationic dyes are not heat-stable in the form of their free color base, i.e. partial neutral decomposition often occurs during exposure to heat.
• Cationic dyes with cyanine chromophore are understood to mean those dyes which have conjugated double bonds, with a nitrogen atom at at least one end of the conjugated system, and in which the delocalization of the positive charge takes place in an alternating manner along the conjugated system (chromophore chain).
• the delocalization of the positive charge is graphically represented in a manner known per se by a dotted line along the conjugate system, in which case only the single bond is drawn in the formulas.
• Cationic dyes whose cation has the formula I are preferably transferred in the R1 R2 and R7 are the same or different and are each independently hydrogen, C1-C4-alkyl, which is optionally substituted by C1-C4-alkoxy, C1-C4-alkylthio, halogen, cyano, hydroxy or phenyl or C5-C7-cycloalkyl or R1 and R2 together with the nitrogen atom connecting them form a 5- or 6-membered, saturated heterocyclic radical, R3 and R5 are the same or different and are each independently hydrogen, C1-C4-alkyl, C1-C4-alkoxy or halogen, R4 is hydrogen or, together with R5, a fused benzo ring, R6 is hydrogen, C1-C4-alkyl, which is optionally substituted by C1-C4-alkoxy, C1-C4-alkylthio, halogen, cyano, hydroxy or phenyl, C
• R14 represents hydrogen, C1-C4 alkyl, which is optionally substituted by halogen, hydroxy or C1-C4-alkoxy, or C1-C4-alkoxy
• R15 and R16 are the same or different and are each independently hydrogen, C1-C4-alkyl, optionally substituted by halogen, hydroxy, C1 -C4-alkoxy or phenyl is substituted, or phenyl optionally substituted by C1-C4-alkyl, C1-C4-alkoxy or halogen
• W represents sulfur or di-C1-C4-alkylmethylene and T represents the remainder CH or nitrogen
• R12 is hydrogen, C1-C4-alkyl, which is optionally substituted by halogen or C1-C4-alkoxy, or phenyl optionally substituted by C1-C4-alkyl, C
• alkyl radicals occurring in the formulas I and II can be either straight-chain or branched. Fluorine, chlorine or bromine are particularly preferred as halogen.
• R1, R2, R6 and R7 in formula I are, for example, hydrogen; Methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl; 2-methoxyethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-isopropoxyethyl, 2-butoxyethyl, 2-sec-butoxyethyl, 2-methoxypropyl, 1-methoxyprop-2-yl, 2-methoxybutyl, 2-ethoxybutyl, 4-isopropoxybutyl; 2-methylthioethyl, 2-ethylthioethyl, 2-propylthioethyl, 2-isopropylthioethyl, 2-butylthioethyl, 2-isobutylthioethyl, 2-methylthiopropyl, 2-ethylthioprop-1-yl, 2-methylthi
• R1 and R2 in formula I together with the nitrogen atom connecting them also represent, for example, the following heterocyclic radicals: pyrrolidino, piperidino, morpholino, N-methylpiperazino, N-ethylpiperazino, N-propylpiperazino, N-isopropylpiperazino, N-butylpiperazino, N-isobutylpiperaz N-sec-butylpiperazino.
• R6 in formula I also represents, for example, phenyl; 2-methylphenyl, 2-ethylphenyl, 2-propylphenyl, 2-isopropylphenyl, 2-butylphenyl, 2,6-dimethylphenyl, 2,6-diethylphenyl, 2,4,6-trimethylphenyl; 2-methoxyphenyl, 2-ethoxyphenyl, 2-propoxyphenyl, 2-isopropoxyphenyl, 2-butoxyphenyl, 2,4-dimethoxyphenyl, 2,6-dimethoxyphenyl; 2-methoxy-4-methylphenyl; 2-fluorophenyl, 2-chlorophenyl, 2-bromophenyl, 2,4-dichlorophenyl or 2,4,6-trichlorophenyl.
• R3 and R5 in formula I are, for example, hydrogen; Methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl; Methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy or sec-butoxy; Fluorine, chlorine, bromine or iodine.
• R12, R13, R14, R15 and R16 in formula II are, for example, hydrogen; Methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl; 2-methoxyethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-isopropoxyethyl, 2-butoxyethyl, 2-sec-butoxyethyl, 2-methoxypropyl, 1-methoxyprop-2-yl, 2-methoxybutyl, 2-ethoxybutyl, 4-isopropoxybutyl; Chloromethyl, difluoromethyl, trifluoromethyl, 2-fluoroethyl, 2-chloroethyl, 2-bromoethyl, pentafluoroethyl, 2-chloro-1,1,2,2-tetrafluoroethyl or nonafluorobutyl.
• R12 and R15 and R16 in formula II are furthermore, for example, phenyl; 2-methylphenyl, 4-methylphenyl, 2-ethylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 4-butylphenyl, 2,4-dimethylphenyl, 2,4,6-trimethylphenyl; 2-methoxyphenyl, 4-methoxyphenyl, 4-ethoxyphenyl, 2,4-dimethoxyphenyl; 2-chlorophenyl, 4-fluorophenyl, 4-bromophenyl or 2,6-dichlorophenyl.
• R14 in formula II can further e.g. Methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy or sec-butoxy mean.
• R14, R15 and R16 also mean, for example, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxybutyl or 4-hydroxybutyl.
• R14 and R15 can also mean, for example, benzyl or 2-phenylethyl.
• W in formula II stands for example for sulfur; Prop-2-ylidene, but-2-ylidene, pent-3-ylidene, hex-2-ylidene, hept-4-ylidene or non-5-ylidene.
• a particularly preferred procedure is that cationic dyes whose cation has the formula I in which R1, R2 and R7 are the same or different and are each independently hydrogen or C1-C4-alkyl, optionally by C1-C4-alkoxy , Halogen, cyano or hydroxy is substituted, or R1 and R2 together with the nitrogen atom connecting them pyrrolidino, piperidino or morpholino, R3 and R5 are the same or different and are each independently hydrogen, C1-C Alkyl-alkyl or C1-C4-alkoxy, R4 hydrogen, R6 the rest in which R8 and R9 are the same or different and are each independently hydrogen, C1-C4-alkyl or C1-C4-alkoxy and R10 are hydrogen and A is oxygen, in their deprotonated electrically neutral form.
• Another particularly preferred procedure consists in that cationic dyes, the cation of which has the formula I, in which R1, R2 and R7 are the same or different and are each independently hydrogen or C1-C4-alkyl, which may be substituted by C1-C4- Alkoxy, halogen, cyano or hydroxy is substituted, or R1 and R2 together with the nitrogen atom connecting them pyrrolidino, piperidino or morpholino, R3 and R5 are the same or different and are each independently hydrogen, C1-C4-alkyl or C1-C4-alkoxy , R4 is hydrogen, R6 is C1-C4-alkyl, which is optionally substituted by C1-C4-alkoxy, halogen, cyano or hydroxy, and A is oxygen, in its deprotonated, electrically neutral form.
• R1, R2 and R7 are the same or different and are each independently hydrogen or C1-C4-alkyl, which may be substituted by C
• Another particularly preferred procedure consists in that cationic dyes, the cation of which has the formula II, in the R11 the heterocyclic radical in which R14 is hydrogen, R15 is C1-C4-alkyl and W is di-C1-C4-alkylmethylene, R12 is phenyl substituted by C1-C4-alkyl or C1-C4-alkoxy, R13 is hydrogen, X and Y are each the rest CH and m 0 mean, in their deprotonated, electrically neutral form.
• cationic dyes suitable for the process according to the invention which are transferred in their deprotonated, electrically neutral form, are those whose cations have the formulas III and IV in which R17 each represents C1-C4 alkyl.
• the cationic dyes in question are in salt form and each have an anion. All customary anions can be considered as anions, and fluoride, chloride, bromide, iodide, sulfate, methosulfate, ethosulfate, carbonate, perchlorate, borate, tetrafluoroborate, tetrachlorozincate, phosphate, methyl sulfonate, phenyl sulfonate, 4-methylphenyl sulfate formate or carboxylate should be mentioned in particular , Acetate, propionate, butyrate, 2-ethylhexanoate, benzoate or 4-methylbenzoate.
• tetrachlorozincate salts to produce the deprotonated, electrically neutral dye form is preferred.
• the dyes whose cations correspond to formulas I to IV are known per se or can be obtained by methods known per se.
• those dyes whose cation corresponds to the formula I in which A represents oxygen are obtained according to those described in DE-A-2 158 121, DE-A-3 011 154, EP-A-5451, EP- A-38736 or GB-A-1 018 797 specified manufacturing methods.
• the other cationic dyes which are transferred in their deprotonated, electrically neutral form in the process according to the invention, can also be prepared by processes known per se, such as those e.g. in K. Venkataraman "The Chemistry of Synthetic Dyes", Volume IV, p. 161; Ullmanns Encyklopadie der Technischen Chemie, 4th edition, volume 13, p. 571; or Rev. Prog. Coloration, Vol. 5, p. 65, 1974.
• Suitable solvents are inert organic solvents, e.g. Isobutanol, toluene, xylene or chlorobenzene. These solutions are then treated with excess alkali alkanolate, e.g. Sodium methanolate or sodium ethanolate are added to convert the cationic dye into its deprotonated, electrically neutral form. It has proven advantageous to work with a 1.1- to 1.3-fold molar excess, based on the cationic dye, of alkali metal alkoxide.
• the resulting solution containing the deprotonated, electrically neutral dye is processed with a binder to form a printing ink.
• the printing ink is applied to the inert carrier using a doctor blade and the dyeing is air-dried.
• binders are ethyl cellulose, polysulfones or polyether sulfones.
• Inert carriers are, for example, tissue paper, blotting paper or glassine paper as well as plastic films with good heat resistance, for example metal-coated polyester, polyamide or polyimide.
• the thickness of the carrier is preferably 3 to 30 ⁇ m. Further carrier materials, binders and solvents suitable for the process according to the invention for the production of the printing inks are described in DE-A-3 524 519.
• Acceptors in the process according to the invention are coated papers, in particular those with an acid-modified coating.
• Corresponding organic or inorganic materials that are sufficiently thermally stable serve as coating materials.
• Suitable organic coating materials are e.g. acid-modified polyacrylonitrile, condensation products based on phenol / formaldehyde (see e.g. US-A-4 082 713), special salicylic acid derivatives (see e.g. DE-A-2 631 832) or acid-modified polyester, the latter being preferred.
• inorganic coating materials are acid-activated clays, as used in carbonless papers (see e.g. Stamm für Textilfabrikation, volume 21, page 767, 1982).
• the deprotonated dye is transferred from the carrier to the acceptor by means of a thermal head which must deliver sufficient heating power to the carrier so that the deprotonated dye evaporates or sublimates within a few milliseconds and is thereby transferred to the plastic-coated, acid-modified paper.
• the transfer takes place at a temperature of 100 to 400 ° C, preferably 150 to 300 ° C.
• an acidic aftertreatment e.g. with gaseous hydrogen chloride or with dilute acetic acid.
• the thermal transfer was carried out with large-area heating jaws instead of a thermal head.
• a binder was not used in the production of the dye carrier to be tested.
• a saturated solution of the cationic dye in the form of the tetrachlorozincate is prepared in a mixture of isobutanol and chlorobenzene (1: 1 v / v).
• a 1.2 molar excess, based on the cationic dye, of sodium methoxide is added to this solution, the deprotonated, electrically neutral form of the dye being formed.
• the formation of the color base can easily be recognized by the resulting change in color of the reaction mixture.
• the mixture is then filtered off and the filtrate is drawn off one to five times on carrier paper using a 20 ⁇ m doctor blade and air-dried. If necessary, the backing paper can also be sprayed with filtrate.
• the paper layer (donor) coated with the dye to be tested is placed with the side on which the dye layer is located on a coated paper (acceptor) and pressed on.
• the transmitter / acceptor is then wrapped with aluminum foil and heated between two heated plates for 30 seconds. (The relatively long period of 30 seconds is chosen for metrological reasons. This ensures that the acceptor can be optimally measured photometrically after the transfer has taken place). If a paper coated with polyester is used as an acceptor, the paper is briefly treated with gaseous hydrogen chloride after the transfer.
• the amount of dye migrated into the paper is determined photometrically.
• the temperature T * [° C] is additionally taken from the plots, at which the extinction A of the colored paper reaches the value 1.
• the cationic dyes listed in Tables 1 and 2 below were converted into their deprotonated, electrically neutral form by method A) and placed on a support, which was tested for sublimation or evaporation behavior by method B). Paper coated with polyester was used as the acceptor. The resulting color tone and the thermal transfer parameters T * and ⁇ E T are listed in the tables.
• the cationic dyes mentioned in Tables 3 and 4 below were converted into their deprotonated, electrically neutral form by method A) and placed on a support, which was tested for sublimation or evaporation behavior by method B).
• a paper with acid-activated clay served as an acceptor as a coating material. The transfer took place here for 30 seconds at a temperature of 130 ° C.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Thermal Transfer Or Thermal Recording In General (AREA)
• Coloring (AREA)

Applications Claiming Priority (2)

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Cited By (8)

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• 1986
  • 1986-12-24 DE DE19863644369 patent/DE3644369A1/de not_active Withdrawn
• 1987
  • 1987-12-17 DE DE8787118714T patent/DE3779741D1/de not_active Expired - Lifetime
  • 1987-12-17 EP EP87118714A patent/EP0273307B1/fr not_active Expired - Lifetime
  • 1987-12-18 US US07/134,979 patent/US4880769A/en not_active Expired - Lifetime
  • 1987-12-22 JP JP62323009A patent/JP2731906B2/ja not_active Expired - Lifetime

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