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EP0462447B1 - Use of azo dyes in thermal transfer printing - Google Patents

Use of azo dyes in thermal transfer printing Download PDF

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Publication number
EP0462447B1
EP0462447B1 EP91109225A EP91109225A EP0462447B1 EP 0462447 B1 EP0462447 B1 EP 0462447B1 EP 91109225 A EP91109225 A EP 91109225A EP 91109225 A EP91109225 A EP 91109225A EP 0462447 B1 EP0462447 B1 EP 0462447B1
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EP
European Patent Office
Prior art keywords
alkyl
hydrogen
azo dyes
formula
tolyloxy
Prior art date
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EP91109225A
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German (de)
French (fr)
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EP0462447A1 (en
Inventor
Rüdiger Sens
Gunther Lamm
Karl-Heinz Etzbach
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BASF SE
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BASF SE
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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
    • B41M5/388—Azo dyes
    • 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 main heat source used is a thermal head with which short heating pulses lasting a fraction of a second can be emitted.
  • a transfer sheet which contains the dye to be transferred together with one or more binders, a carrier material and possibly other auxiliaries such as release agents or crystallization-inhibiting substances is heated from the rear by the thermal head.
  • the dye diffuses from the transfer sheet into the surface coating of the substrate, e.g. into the plastic layer of a coated paper.
  • the main advantage of this method is that the amount of ink transferred and thus the color gradation can be controlled in a targeted manner via the energy to be delivered to the thermal head.
  • Thermal transfer printing generally uses the three subtractive primary colors yellow, magenta and cyan, possibly also black, whereby the dyes used must have the following properties for optimal color recording: easy thermal transferability, low tendency to migrate within or from the surface coating of the recording medium at room temperature , high thermal and photochemical stability as well as resistance to moisture and chemicals, no tendency to crystallize when storing the transfer sheet, a suitable color for the subtractive color mixture, a high molar absorption coefficient and easy technical accessibility.
  • non-prepublished EP-A-442 466 (earlier right for the designated contracting states DE, FR and GB) uses fluorophenylazopyridone dyes for thermal transfer printing.
  • the azo dyes I themselves are known per se or can be obtained by known methods (EP-B-111 236).
  • the invention was therefore based on the object of finding suitable yellow dyes for thermal transfer printing which come closer to the required property profile than the dyes known hitherto.
  • a method for transferring azo dyes by diffusion from a support onto a plastic-coated substrate using a thermal head was found, which is characterized in that a support is used for this purpose, on which one or more of the azo dyes I defined at the outset are located.
  • radicals R 2 by definition, acetyl and cyano are particularly suitable.
  • R 4 or R 5 radicals can be especially hydrogen, chlorine and cyano, but also fluorine, bromine, nitro and trihalomethyl groups such as trifluoromethyl and trichloromethyl.
  • R 4 or R 5 have the formulas -CO-H, -CO-R 6 , -O-CO-R 6 , -CO-OR 6 , -SO-OR 6 , -0-SO-OR 6 , -CO-NR 7 R 8 , -O-CO-NR 7 R 8 , -S0 2 -NR 7 R 8 or -0-S0 2 -NR 7 R 8 ; those of the formula -CO-OR 6 are particularly preferred.
  • the radical R 6 is one of the C 1 -C 12 -alkyl groups or ⁇ -phenoxy, ⁇ -tolyloxy, ⁇ -benzyloxy or ⁇ -cyclohexyloxy-C 1 -C 12 alkyl groups listed above, the C chain of which is in each case can be interrupted by one or two oxygen atoms in ether function.
  • Suitable radicals R 7 or R 8 are the unsubstituted C 1 -C 12 -alkyl groups already mentioned.
  • Preferred azo dyes 1 can be found in the examples.
  • the dyes I to be used according to the invention are distinguished from the yellow dyes previously used for thermal transfer printing by the following properties: easier thermal transferability despite the relatively high molecular weight, improved migration properties in the recording medium at room temperature, higher lightfastness, better resistance to moisture and chemicals, better solubility the production of the printing ink, higher color strength and easier technical accessibility.
  • the azo dyes I show significantly better color purity, in particular in dye mixtures, and give improved black prints.
  • the transfer sheets required as dye donors for the thermal transfer printing process according to the invention are prepared as follows:
  • the azo dyes I are dissolved in an organic solvent, e.g. Isobutanol, methyl ethyl ketone, methylene chloride, chlorobenzene, toluene, tetrahydrofuran or mixtures thereof, processed with one or more binders and possibly other auxiliaries such as release agents or crystallization inhibitors to give a printing ink which preferably contains the dyes in molecularly dispersed solution.
  • the printing ink is then applied to an inert support and dried.
  • Suitable binders for the use of the azo dyes I according to the invention are all materials which are soluble in organic solvents and which are known to serve for thermal transfer printing, i.e. Cellulose derivatives such as methyl cellulose, hydroxypropyl cellulose, cellulose acetate or cellulose acetobutyrate, especially ethyl cellulose, ethyl hydroxyethyl cellulose and cellulose acetate hydrogen phthalate, starch, alginates, alkyd resins such as polyvinyl alcohol or polyvinyl pyrrolidone and in particular polyvinyl acetate and polyvinyl butyrate.
  • Cellulose derivatives such as methyl cellulose, hydroxypropyl cellulose, cellulose acetate or cellulose acetobutyrate, especially ethyl cellulose, ethyl hydroxyethyl cellulose and cellulose acetate hydrogen phthalate, starch, alginates, alkyd resins such as polyvinyl alcohol or poly
  • polymers and copolymers of acrylates or their derivatives such as polyacrylic acid, polymethyl methacrylate or styrene acrylate copolymers, polyester resins, polyamide resins, polyurethane resins or natural resins such as e.g. Gum arabic into consideration.
  • binders are often recommended, e.g. those made of ethyl cellulose and polyvinyl butyrate in a weight ratio of 2: 1.
  • the weight ratio of binder to dye is usually 8: 1 to 1: 1, preferably 5: 1 to 2: 1.
  • Inert carrier materials are, for example, tissue paper, blotting paper or glassine paper as well as films made of heat-resistant plastics such as polyesters, polyamides or polyimides, these films also being able to be metal-coated.
  • the inert carrier can additionally be coated with a lubricant on the side facing the thermal head in order to prevent the thermal head from sticking to the carrier material.
  • Suitable lubricants are, for example, silicones or polyurethanes, as described in EP-A-216 483.
  • the thickness of the dye carrier is generally 3 to 30 ⁇ m, preferably 5 to 10 ⁇ m.
  • the substrate to be printed for example paper, must in turn be coated with a binder which absorbs the dye during the printing process.
  • a binder which absorbs the dye during the printing process.
  • Polymeric materials whose glass transition temperature Tg is between 50 and 100 ° C., for example polycarbonates and polyester, are preferably used for this purpose. Further details can be found in EP-A-227 094, EP-A-133 012, EP-A-133 011, JP-A-199 997/1986 or JP-A 283 595/1986.
  • a thermal head which can be heated to temperatures up to over 300 ° C., so that the dye transfer takes place within a maximum time of 15 msec.
  • transfer sheets were produced in a conventional manner from 8 ⁇ m thick polyester film, which was provided with an approximately 5 ⁇ m thick transfer layer made of a binder B, which each contained 0.25 g of azo dye I.
  • the weight ratio of binder to dye was 4: 1 in each case.
  • the substrate (slave) to be printed consisted of paper of approximately 120 ⁇ m thick, which was coated with an 8 ⁇ m thick plastic layer (Hitachi Color Video Print Paper).
  • the coated side of the encoder and slave was placed on top of one another, wrapped with aluminum foil and heated to a temperature between 70 and 80 ° C. for two minutes between two heating plates. With similar samples, this process was repeated three times at a higher temperature between 80 and 120 ° C.
  • the amount of dye diffused into the plastic layer of the receiver is proportional to the optical density, which was determined as absorbance A photometrically after the respective heating to the temperatures given above.
  • the temperature T * at which the extinction reaches the value 1 can also be taken from the application, ie the transmitted light intensity is one tenth of the incident light intensity.
  • the smaller the temperature T * the better the thermal transferability of the investigated dye.
  • binder B used in each case is indicated.
  • EC ethyl cellulose
  • PVB polyvinyl butyrate

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

Description

Die vorliegende Erfindung betrifft die Verwendung von Azofarbstoffen der allgemeinen Formel I

Figure imgb0001
für den Thermotransferdruck, in der die Substituenten folgende Bedeutung haben:

  • R1 Wasserstoff, eine Amino-, Hydroxyl- oder C1-C3-Alkylgruppe;
  • R2 Wasserstoff, eine Acetyl-, Carbamoyl- oder Cyanogruppe;
  • R3 eine m-Phenoxy-, m-Tolyloxy-, m-Benzyloxy- oder ω-Cyclohexyloxy-C1-C12-alkylgruppe, deren C-Kette durch ein oder zwei der folgenden nicht benachbarten Glieder -O-, -CO-, -O-CO- oder -CO-O-unterbrochen sein kann und die ein oder zwei der folgenden Substituenten tragen kann: Halogen, Hydroxy, C1 -C2-Alkyl, Phenyl oder Cyclohexyl;
  • R4, R5 Wasserstoff, Halogen (ausgenommen Fluor für die Vertragsstaaten DE, FR und GB), Cyano-, Nitro- oder Trihalogenmethylgruppen; Reste der Formeln -CO-H, -CO-R6 , -O-CO-R6 , -CO-OR6 , -SO-OR6 , -O-SO-OR6 , -CO-NR7 R8 ,-O-CO-NR7 R8 , -S02-NR7R8 oder -O-S02-NR7 R8 wobei
  • R6 eine C1-C12-Alkylgruppe, eine m-Phenoxy-, m-Tolyloxy-, m-Benzyloxy- oder ω-Cyclohexyloxy-C1-C12-alkylgruppe bezeichnet, wobei die C-Kette der Alkylgruppen bzw. der ω-substituierten Alkylgruppen durch ein oder zwei Sauerstoffatome in Etherfunktion unterbrochen sein kann,
  • R7 eine C1-C12-Alkylgruppe bedeutet und
  • R8 für Wasserstoff oder einen der Reste R7 steht, sowie speziell ein Verfahren zur Übertragung dieser Azofarbstoffe durch Diffusion von einem Träger auf ein mit Kunststoff beschichtetes Substrat mit Hilfe eines Thermokopfes.
The present invention relates to the use of azo dyes of the general formula I.
Figure imgb0001
 for thermal transfer printing, in which the substituents have the following meaning:
  • R 1 is hydrogen, an amino, hydroxyl or C 1 -C 3 alkyl group;
  • R 2 is hydrogen, an acetyl, carbamoyl or cyano group;
  • R 3 is an m-phenoxy, m-tolyloxy, m-benzyloxy or ω-cyclohexyloxy-C 1 -C 12 alkyl group, the C chain of which is linked by one or two of the following non-adjacent links -O-, -CO- , -O-CO- or -CO-O-can be interrupted and which can carry one or two of the following substituents: halogen, hydroxy, C 1 -C 2 alkyl, phenyl or cyclohexyl;
  • R 4 , R 5 are hydrogen, halogen (except fluorine for the contracting states DE, FR and GB), cyano, nitro or trihalomethyl groups; Radicals of the formulas -CO-H, -CO-R 6 , -O-CO-R 6 , -CO-OR 6 , -SO-OR 6 , -O-SO-OR 6 , -CO-NR 7 R 8 , -O-CO-NR 7 R 8 , -S0 2 -NR 7 R 8 or -O-S0 2 -NR 7 R 8 where
  • R 6 denotes a C 1 -C 12 alkyl group, an m-phenoxy, m-tolyloxy, m-benzyloxy or ω-cyclohexyloxy-C 1 -C 12 alkyl group, the C chain of the alkyl groups or the ω-substituted alkyl groups can be interrupted by one or two oxygen atoms in ether function,
  • R 7 represents a C 1 -C 12 alkyl group and
  • R 8 stands for hydrogen or one of the radicals R 7 , and specifically a process for the transfer of these azo dyes by diffusion from a support onto a plastic-coated substrate with the aid of a thermal head.

Die Technik des Thermotransferdrucks ist allgemein bekannt; als Wärmequelle kommt neben Laser und IR-Lampe vor allem ein Thermokopf zur Anwendung, mit dem kurze Heizimpulse der Dauer von Bruchteilen einer Sekunde abgegeben werden können.The technique of thermal transfer printing is well known; In addition to the laser and IR lamp, the main heat source used is a thermal head with which short heating pulses lasting a fraction of a second can be emitted.

Bei dieser bevorzugten Ausführungsform des Thermotransferdrucks wird ein Transferblatt, das den zu übertragenden Farbstoff zusammen mit einem oder mehreren Bindemitteln, einem Trägermaterial und eventuell weiteren Hilfsmitteln wie Trennmitteln oder kristallisationshemmenden Stoffen enthält, von der Rückseite her durch den Thermokopf erhitzt. Dabei diffundiert der Farbstoff aus dem Transferblatt in die Oberflächenbeschichtung des Substrates, z.B. in die Kunststoffschicht eines beschichteten Papiers.In this preferred embodiment of thermal transfer printing, a transfer sheet which contains the dye to be transferred together with one or more binders, a carrier material and possibly other auxiliaries such as release agents or crystallization-inhibiting substances is heated from the rear by the thermal head. The dye diffuses from the transfer sheet into the surface coating of the substrate, e.g. into the plastic layer of a coated paper.

Der wesentliche Vorteil dieses Verfahrens besteht darin, daß über die an den Thermokopf abzugebende Energie die übertragene Farbmenge und damit die Farbabstufung gezielt gesteuert werden kann.The main advantage of this method is that the amount of ink transferred and thus the color gradation can be controlled in a targeted manner via the energy to be delivered to the thermal head.

Beim Thermotransferdruck werden allgemein die drei subtraktiven Grundfarben Gelb, Magenta und Cyan, gegebenenfalls zusätzlich Schwarz, verwendet, wobei die eingesetzten Farbstoffe für eine optimale Farbaufzeichnung folgende Eigenschaften aufweisen müssen: leichte thermische Transferierbarkeit, geringe Neigung zur Migration innerhalb oder aus der Oberflächenbeschichtung des Aufnahmemediums bei Raumtemperatur, hohe thermische und photochemische Stabilität sowie Resistenz gegen Feuchtigkeit und Chemikalien, keine Tendenz zur Kristallisation bei Lagerung des Transferblattes, einen geeigneten Farbton für die subtraktive Farbmischung, einen hohen molaren Absorptionskoeffizienten und leichte technische Zugänglichkeit.Thermal transfer printing generally uses the three subtractive primary colors yellow, magenta and cyan, possibly also black, whereby the dyes used must have the following properties for optimal color recording: easy thermal transferability, low tendency to migrate within or from the surface coating of the recording medium at room temperature , high thermal and photochemical stability as well as resistance to moisture and chemicals, no tendency to crystallize when storing the transfer sheet, a suitable color for the subtractive color mixture, a high molar absorption coefficient and easy technical accessibility.

Diese Anforderungen sind gleichzeitig nur sehr schwer zu erfüllen. Insbesondere die bislang verwendeten Gelbfarbstoffe können nicht überzeugen. Dies trifft auch für die aus den EP-A-247 737, JP-A-12 393/1986, JP-A-244 595/1986 und JP-A-262 191/1986 bekannten und für den Thermotransferdruck empfohlenen Azopyridone zu, die sich von den Verbindungen 1 u.a. durch die Substituenten am Pyridon-Stickstoff unterscheiden.At the same time, these requirements are very difficult to meet. In particular, the yellow dyes previously used cannot convince. This also applies to the azopyridones known from EP-A-247 737, JP-A-12 393/1986, JP-A-244 595/1986 and JP-A-262 191/1986 and recommended for thermal transfer printing differ from compounds 1 and others distinguish by the substituents on the pyridone nitrogen.

Weiterhin werden in der nicht vorveröffentlichten EP-A-442 466 (älteres Recht für die benannten Vertragsstaaten DE, FR und GB) Fluorphenylazopyridonfarbstoffe für den Thermotransferdruck eingesetzt.Furthermore, the non-prepublished EP-A-442 466 (earlier right for the designated contracting states DE, FR and GB) uses fluorophenylazopyridone dyes for thermal transfer printing.

Die Azofarbstoffe I selbst sind an sich bekannt oder nach bekannten Methoden erhältlich (EP-B-111 236).The azo dyes I themselves are known per se or can be obtained by known methods (EP-B-111 236).

Der Erfindung lag daher die Aufgabe zugrunde, für den Thermotransferdruck geeignete Gelbfarbstoffe zu finden, die dem geforderten Eigenschaftsprofil näherkommen als die bisher bekannten Farbstoffe.The invention was therefore based on the object of finding suitable yellow dyes for thermal transfer printing which come closer to the required property profile than the dyes known hitherto.

Demgemäß wurde die Verwendung der eingangs definierten Azofarbstoffe I für den Thermotransferdruck gefunden.Accordingly, the use of the azo dyes I defined at the outset was found for thermal transfer printing.

Außerdem wurde ein Verfahren zur Übertragung von Azofarbstoffen durch Diffusion von einem Träger auf ein mit Kunststoff beschichtetes Substrat mit Hilfe eines Thermokopfes gefunden, welches dadurch gekennzeichnet ist, daß man hierfür einen Träger verwendet, auf dem sich ein oder mehrere der eingangs definierten Azofarbstoffe I befinden.In addition, a method for transferring azo dyes by diffusion from a support onto a plastic-coated substrate using a thermal head was found, which is characterized in that a support is used for this purpose, on which one or more of the azo dyes I defined at the outset are located.

Weiterhin wurde eine bevorzugte Ausführungsform dieses Verfahrens gefunden, welche dadurch gekennzeichnet ist, daß man hierzu Farbstoffe der Formel la

Figure imgb0002
verwendet, in der die Substituenten folgende Bedeutung haben:

  • R3' eine ω-Phenoxy-, ω-Tolyloxy-, m-Benzyloxy- oder ω-Cyclohexyloxy-C1-C12 -alkylgruppe, deren C-Kette durch ein oder zwei Sauerstoffatome in Etherfunktion unterbrochen sein kann;
  • R4', R5' Wasserstoff, Chlor oder eine Cyanogruppe; Reste der Formel -CO-OR6 Unter den definitionsgemäßen Resten R1 werden Ethyl und Propyl sowie besonders Methyl bevorzugt.
Furthermore, a preferred embodiment of this process was found, which is characterized in that dyes of the formula la
Figure imgb0002
 used, in which the substituents have the following meaning:
  • R 3 'is an ω-phenoxy, ω-tolyloxy, m-benzyloxy or ω-cyclohexyloxy-C 1 -C 12 alkyl group, the C chain of which can be interrupted by one or two oxygen atoms in ether function;
  • R 4 ', R 5 ' is hydrogen, chlorine or a cyano group; Residues of the formula -CO-O R6 Among the radicals R 1 as defined , ethyl and propyl and especially methyl are preferred.

Von den definitionsgemäßen Reste R2 eignen sich besonders Acetyl sowie ganz besonders Cyano.Of the radicals R 2 by definition, acetyl and cyano are particularly suitable.

Geeignete Alkylreste R3 sind beispielsweise Methyl, Ethyl, Propyl, Isopropyl, Butyl, Isobutyl, sec.-Butyl, tert.-Butyl, Pentyl, Isopentyl, sec.-Pentyl, tert.-Pentyl, Hexyl, 2-Methylpentyl, Heptyl, Octyl, 2-Ethylhexyl, Nonyl, Decyl, Undecyl, Dodecyl und verzweigte Reste dieser Art, die jeweils in ω-Stellung eine Phenoxy-, Tolyloxy-, Benzyloxy- oder Cyclohexyloxygruppe tragen, wie vor allem (dabei bedeutet Ph = Phenyl und C6 H11 = Cyclohexyl):

  • -(CH2)2-0-Ph, -(CH2)2-0-Ph-2-CH3, -(CH2)2-0-Ph-3-CH3, -(CH2)2-0-CH2-Ph,
  • -(CH2)2 -O-C6 H11 ,
  • -(CH2)3-0-CH2-Ph, -(CH2)3-O-C6 H11 ,
  • -(CH2)4-0-Ph, -(CH2)4-0-CH2-Ph, -(CH2)4-O-C6 H11 ,
  • -(CH2)10-O-Ph und -(CH2)4-CH(C2H5)-CH2-O-Ph.
Suitable alkyl radicals R 3 are, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, tert-pentyl, hexyl, 2-methyl pentyl, heptyl, Octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl and branched radicals of this type, each of which has a phenoxy, tolyloxy, benzyloxy or cyclohexyloxy group in the ω position, as especially (where Ph = phenyl and C 6 H 11 = cyclohexyl):
  • - (CH 2 ) 2 -0-Ph, - (CH 2 ) 2 -0-Ph-2-CH 3 , - (CH 2 ) 2 -0-Ph-3-CH 3 , - (CH 2 ) 2 - 0-CH 2 -Ph,
  • - (CH 2 ) 2 -OC 6 H 11 ,
  • - (CH 2 ) 3 -0-CH 2 -Ph, - (CH 2 ) 3 -OC 6 H 11 ,
  • - (CH 2 ) 4 -0-Ph, - (CH 2 ) 4 -0-CH 2 -Ph, - (CH 2 ) 4 -OC 6 H 11 ,
  • - (CH 2 ) 10 -O-Ph and - (CH 2 ) 4 -CH (C 2 H 5 ) -CH 2 -O-Ph.

Die C-Kette der genannten Alkylreste R3 kann durch ein oder zwei nicht benachbarte Glieder -CO-, -O-CO-, -CO-O- oder besonders -O- unterbrochen sein und kann bis zu zwei Substituenten wie Brom und Chlor, Hydroxy, Methyl, Ethyl, Phenyl oder Cyclohexyl tragen; beispielsweise sind hier zu nennen:

  • -(CH2)4-CO-(CH2)4-O-(CH2)a-O-Ph;
  • -(CH2)4-O-CO-(CH2)3-O-Ph, -(CH2)3-O-CO-(CH2)6-O-C6 H11;
  • -(CH2)4-CO-O-(CH2)8-O-Ph und -(CH2)3-CO-0-(CH2)6-0-CH2-Ph;
  • besonders bevorzugt -(CH2)3-0-(CH2)2-0-Ph, -(CH2)3-0-(CH2)2-0-Ph-2-CH3,
  • -(CH2)3-0-(CH2)2-0-Ph-3-CH3,
  • bevorzugt -(CH2)3-0-(CH2)2-0-CH2-Ph, -(CH2)3-0-(CH2)2-0-C6 H11,
  • -(CH2)2-0-(CH2)2-0-Ph, -[(CH2)2-0]2-(CH2)2-0-Ph,
  • -(CH2)3-0-CH(CH3)-CH2-0-Ph,
  • -(CH2)3-0-(CH2)2-0-(CH2)2-0-Ph, -(CH2)3-0-(CH2)2-0-(CH2)2-0-C6 H11 ,
  • -(CH2)2-O-(CH2)3-O-CH2-Ph, -(CH2)2-O-(CH2)2-CH(OH)-(CH2)2-O-Ph und
  • -(CH2)3-0-(CH2)2-CH(C6 H1 1)-CH2-0-Ph.
The C chain of the alkyl radicals R 3 mentioned can be interrupted by one or two non-adjacent links -CO-, -O-CO-, -CO-O- or especially -O- and can have up to two substituents such as bromine and chlorine, Carry hydroxy, methyl, ethyl, phenyl or cyclohexyl; Examples include:
  • - (CH 2 ) 4 -CO- (CH 2 ) 4 -O- (CH 2 ) aO-Ph;
  • - (CH 2 ) 4 -O-CO- (CH 2 ) 3 -O-Ph, - (CH 2 ) 3 -O-CO- (CH 2 ) 6 -OC 6 H 11 ;
  • - (CH 2 ) 4 -CO-O- (CH 2 ) 8 -O-Ph and - (CH 2 ) 3 -CO-0- (CH 2 ) 6 -0-CH 2 -Ph;
  • particularly preferred - (CH 2 ) 3 -0- (CH 2 ) 2 -0-Ph, - (CH 2 ) 3 -0- (CH 2 ) 2 -0-Ph-2-CH 3 ,
  • - (CH 2 ) 3 -0- (CH 2 ) 2 -0-Ph-3-CH 3 ,
  • preferably - (CH 2 ) 3 -0- (CH 2 ) 2 -0-CH 2 -Ph, - (CH 2 ) 3 -0- (CH 2 ) 2 -0-C 6 H 11 ,
  • - (CH 2 ) 2 -0- (CH 2 ) 2 -0-Ph, - [(CH 2 ) 2 -0] 2 - (CH 2 ) 2 -0-Ph,
  • - (CH 2 ) 3 -0-CH (CH 3 ) -CH 2 -0-Ph,
  • - (CH 2 ) 3 -0- (CH 2 ) 2 -0- (CH 2 ) 2 -0-Ph, - (CH 2 ) 3 -0- (CH 2 ) 2 -0- (CH 2 ) 2 - 0-C 6 H 11 ,
  • - (CH 2 ) 2 -O- (CH 2 ) 3 -O-CH 2 -Ph, - (CH 2 ) 2 -O- (CH 2 ) 2 -CH (OH) - (CH 2 ) 2 -O- Ph and
  • - (CH 2 ) 3 -0- (CH 2 ) 2 -CH (C 6 H 1 1 ) -CH 2 -0-Ph.

Reste R4 oder R5 können vor allem Wasserstoff, Chlor und Cyano, daneben auch Fluor, Brom, Nitro und Trihalogenmethylgruppen wie Trifluormethyl und Trichlormethyl sein.R 4 or R 5 radicals can be especially hydrogen, chlorine and cyano, but also fluorine, bromine, nitro and trihalomethyl groups such as trifluoromethyl and trichloromethyl.

Weiterhin geeignete Reste R4 oder R5 weisen die Formeln -CO-H, -CO-R6, -O-CO-R6, -CO-OR6, -SO-OR6, -0-SO-OR6, -CO-NR7R8, -O-CO-NR7R8, -S02-NR7R8 oder -0-S02-NR7R8 auf; dabei sind diejenigen der Formel -CO-OR6 besonders bevorzugt.Further suitable radicals R 4 or R 5 have the formulas -CO-H, -CO-R 6 , -O-CO-R 6 , -CO-OR 6 , -SO-OR 6 , -0-SO-OR 6 , -CO-NR 7 R 8 , -O-CO-NR 7 R 8 , -S0 2 -NR 7 R 8 or -0-S0 2 -NR 7 R 8 ; those of the formula -CO-OR 6 are particularly preferred.

Der Rest R6 ist dabei eine der oben aufgeführten C1-C12-Alkylgruppen oder ω-Phenoxy-, ω-Tolyloxy-, ω-Benzyloxy- oder ω-Cyclohexyloxy-C1-C12-alkylgruppen, deren C-Kette jeweils durch ein oder zwei Sauerstoffatome in Etherfunktion unterbrochen sein kann. Geeignete Reste R7 oder R8 sind die bereits genannten unsubstituierten C1-C12-Alkylgruppen.The radical R 6 is one of the C 1 -C 12 -alkyl groups or ω-phenoxy, ω-tolyloxy, ω-benzyloxy or ω-cyclohexyloxy-C 1 -C 12 alkyl groups listed above, the C chain of which is in each case can be interrupted by one or two oxygen atoms in ether function. Suitable radicals R 7 or R 8 are the unsubstituted C 1 -C 12 -alkyl groups already mentioned.

Als Beispiele für die Reste R4 oder R5 seien die folgenden Gruppierungen genannt:The following groupings may be mentioned as examples of the radicals R 4 or R 5 :

  • -CO-CH3, -CO-C2H5, -CO-C6H13, -CO-C11H23,-CO-CH 3 , -CO-C 2 H 5 , -CO-C 6 H 13 , -CO-C 11 H 23 ,
  • -CO-(CH2)3-0-(CH2)2-0-Ph, -CO-(CH2)4-0-C3H7 und -CO-(CH2)8-0-CH3;-CO- (CH 2 ) 3 -0- (CH 2 ) 2 -0-Ph, -CO- (CH 2 ) 4 -0-C 3 H 7 and -CO- (CH 2 ) 8 -0-CH3;
  • -0-CO-CH3, -O-CO-C4H9 , -O-CO-C7H15,-0-CO-CH 3 , -O-CO-C 4 H 9 , -O-CO-C 7 H 15 ,
  • -O-CO-(CH2)3-O-CH3 und -O-CO-(CH2)4-O-C4H9;-O-CO- (CH 2 ) 3 -O-CH 3 and -O-CO- (CH 2 ) 4 -OC 4 H 9 ;
  • -CO-0-CH3, -CO-O-C2H5, -CO-O-C4H9 , -CO-O-C6H13 , -CO-O-C7 H1 s ,-CO-0-CH 3 , -CO-OC 2 H 5 , -CO-OC 4 H 9 , -CO-OC 6 H 13 , -CO-OC 7 H 1 s,
  • -CO-O-(CH2)4-O-CH3, -CO-0-CH(CH3)-CH2-0-CH3,-CO-O- (CH 2 ) 4 -O-CH 3 , -CO-0-CH (CH 3 ) -CH 2 -0-CH 3 ,
  • -CO-0-(CH2)3 -O-C4 H9, -CO-0-(CH2 )3 -O-C6 H1 3, -CO-0-(CH2)2 -0-(CH2)2 -0-C4 H9,-CO-0- (CH 2 ) 3 -OC 4 H 9 , -CO-0- (CH 2 ) 3 -OC 6 H 1 3 , -CO-0- (CH 2 ) 2 -0- (CH 2 ) 2 -0-C4 H 9 ,
  • -CO-0-(CH2)2-0-Ph, -CO-0-(CH2)3-0-Ph, -CO-0-(CH2)4-0-Ph,-CO-0- (CH 2 ) 2 -0-Ph, -CO-0- (CH 2 ) 3 -0-Ph, -CO-0- (CH 2 ) 4 -0-Ph,
  • -CO-O-(CH2)4-O-C6H11 und -CO-0-(CH2)8-0-CH2-Ph;-CO-O- (CH 2 ) 4 -OC 6 H 11 and -CO-0- (CH 2 ) 8 -0-CH 2 -Ph;
  • -SO-0-CH3, -SO-O-C2 H5, -SO-O-C5 H11,-SO-0-CH 3 , -SO-OC 2 H 5 , -SO-OC 5 H 11 ,
  • -SO-0-(CH2)2-0-(CH2)2-0-CH3 und -SO-O-(CH2)4-O-C2Hs;-SO-0- (CH 2 ) 2 -0- (CH 2 ) 2 -0-CH 3 and -SO-O- (CH 2 ) 4 -OC 2 Hs;
  • -0-SO-0-CH3, -O-SO-O-C4H9 , -O-SO-O-C10H21,-0-SO-0-CH 3 , -O-SO-OC 4 H 9 , -O-SO-OC 10 H 21 ,
  • -O-SO-O-(CH2)3-O-C4H9 und -0-SO-0-(CH2)5-0-C3H7;-O-SO-O- (CH 2 ) 3 -OC 4 H 9 and -0-SO-0- (CH 2 ) 5 -0-C 3 H 7 ;
  • -CO-NH-C4H9 , -CO-NH-C7H15, -CO-NH-C9H19 , -CO-NH-C10H21 ,-CO-NH-C 4 H 9 , -CO-NH-C 7 H 15 , -CO-NH-C 9 H 19 , -CO-NH-C 10 H 21 ,
  • -CO-NH-(CH2)3-0-(CH2)2-0-C2H5,-CO-NH- (CH 2 ) 3 -0- (CH 2 ) 2 -0-C 2 H 5 ,
  • -CO-N(CH3)-C6H13, -CO-N(C2H5)-C3H7 und -CO-N(C3H7)-C3H7;-CO-N (CH 3 ) -C 6 H 13 , -CO-N (C 2 H 5 ) -C 3 H 7 and -CO-N (C 3 H 7 ) -C 3 H 7 ;
  • -O-CO-NH-C6 H1 3 und -O-CO-N(C5 H1, )-C5 H11;-O-CO-NH-C 6 H 1 3 and -O-CO-N (C 5 H 1 ,) -C 5 H 11 ;
  • -S02-NH-C7H15, -S02-NH-C10H21, -S02-NH-(CH2)3-0-C2H5,-S0 2 -NH-C 7 H 15 , -S0 2 -NH-C 10 H 21 , -S0 2 -NH- (CH 2 ) 3 -0-C 2 H 5 ,
  • -S02-N(C4H9)-C4H9 und -S02-N(C3H7)-(CH2)4-0-C4H9;-S0 2 -N (C 4 H 9 ) -C 4 H 9 and -S0 2 -N (C 3 H 7 ) - (CH 2 ) 4 -0-C 4 H 9 ;
  • -0-S02-NH-C7H15 und -0-S02-N((CH2)3-0-CH3)-(CH2)3-0-CH3.-0-S0 2 -NH-C 7 H 15 and -0-S0 2 -N ((CH 2 ) 3 -0-CH 3 ) - (CH 2 ) 3 -0-CH 3 .

Bevorzugte Azofarbstoffe 1 sind den Beispielen zu entnehmen.Preferred azo dyes 1 can be found in the examples.

Die erfindungsgemäß zu verwendenden Farbstoffe I zeichnen sich gegenüber den bisher für den Thermotransferdruck eingesetzten Gelbfarbstoffen durch folgende Eigenschaften aus: leichtere thermische Transferierbarkeit trotz des relativ hohen Molekulargewichts, verbesserte Migrationseigenschaften im Aufnahmemedium bei Raumtemperatur, höhere Lichtechtheit, bessere Resistenz gegen Feuchtigkeit und Chemikalien, bessere Löslichkeit bei der Herstellung der Druckfarbe, höhere Farbstärke sowie leichtere technische Zugänglichkeit.The dyes I to be used according to the invention are distinguished from the yellow dyes previously used for thermal transfer printing by the following properties: easier thermal transferability despite the relatively high molecular weight, improved migration properties in the recording medium at room temperature, higher lightfastness, better resistance to moisture and chemicals, better solubility the production of the printing ink, higher color strength and easier technical accessibility.

Zudem zeigen die Azofarbstoffe I deutlich bessere Farbtonreinheit, insbesondere in Farbstoffmischungen, und ergeben verbesserte Schwarz-Drucke.In addition, the azo dyes I show significantly better color purity, in particular in dye mixtures, and give improved black prints.

Die für das erfindungsgemäße Thermotransferdruckverfahren benötigten, als Farbstoffgeber fungierenden Transferblätter werden folgendermaßen präpariert: Die Azofarbstoffe I werden in einem organischen Lösungsmittel, wie z.B. Isobutanol, Methylethylketon, Methylenchlorid, Chlorbenzol, Toluol, Tetrahydrofuran oder deren Mischungen, mit einem oder mehreren Bindemitteln sowie eventuell weiteren Hilfsmitteln wie Trennmitteln oder kristallisationshemmenden Stoffen zu einer Druckfarbe verarbeitet, welche die Farbstoffe vorzugsweise molekular-dispers gelöst enthält. Die Druckfarbe wird anschließend auf einen inerten Träger aufgetragen und getrocknet.The transfer sheets required as dye donors for the thermal transfer printing process according to the invention are prepared as follows: The azo dyes I are dissolved in an organic solvent, e.g. Isobutanol, methyl ethyl ketone, methylene chloride, chlorobenzene, toluene, tetrahydrofuran or mixtures thereof, processed with one or more binders and possibly other auxiliaries such as release agents or crystallization inhibitors to give a printing ink which preferably contains the dyes in molecularly dispersed solution. The printing ink is then applied to an inert support and dried.

Als Bindemittel für die erfindungsgemäße Verwendung der Azofarbstoffe I eignen sich alle in organischen Lösungsmitteln löslichen Materialien, die bekanntermaßen für den Thermotransferdruck dienen, also z.B. Cellulosederivate wie Methylcellulose, Hydroxypropylcellulose, Celluloseacetat oder Celluloseacetobutyrat, vor allem Ethylcellulose, Ethylhydroxyethylcellulose und Celluloseacetathydrogenphthalat, Stärke, Alginate, Alkydharze wie Polyvinylalkohol oder Polyvinylpyrrolidon sowie besonders Polyvinylacetat und Polyvinylbutyrat. Daneben kommen Polymere und Copolymere von Acrylaten oder deren Derivaten wie Polyacrylsäure, Polymethylmethacrylat- oder Styrolacrylatcopolymere, Polyesterharze, Polyamidharze, Polyurethanharze oder natürliche Harze wie z.B. Gummi Arabicum in Betracht.Suitable binders for the use of the azo dyes I according to the invention are all materials which are soluble in organic solvents and which are known to serve for thermal transfer printing, i.e. Cellulose derivatives such as methyl cellulose, hydroxypropyl cellulose, cellulose acetate or cellulose acetobutyrate, especially ethyl cellulose, ethyl hydroxyethyl cellulose and cellulose acetate hydrogen phthalate, starch, alginates, alkyd resins such as polyvinyl alcohol or polyvinyl pyrrolidone and in particular polyvinyl acetate and polyvinyl butyrate. In addition there are polymers and copolymers of acrylates or their derivatives such as polyacrylic acid, polymethyl methacrylate or styrene acrylate copolymers, polyester resins, polyamide resins, polyurethane resins or natural resins such as e.g. Gum arabic into consideration.

Häufig empfehlen sich Mischungen dieser Bindemittel, z.B. solche aus Ethylcellulose und Polyvinylbutyrat im Gewichtsverhältnis 2 : 1.Mixtures of these binders are often recommended, e.g. those made of ethyl cellulose and polyvinyl butyrate in a weight ratio of 2: 1.

Das Gewichtsverhältnis von Bindemittel zu Farbstoff beträgt in der Regel 8 : 1 bis 1 : 1, vorzugsweise 5 : 1 bis 2 : 1.The weight ratio of binder to dye is usually 8: 1 to 1: 1, preferably 5: 1 to 2: 1.

Als Hilfsmittel werden z.B. Trennmittel auf der Basis von perfluorierten Alkylsulfonamidoalkylestern oder Siliconen, wie sie in der EP-A-227 092 bzw. der EP-A-192 435 beschrieben sind, und besonders organische Additive, welche das Auskristallisieren der Transferfarbstoffe bei Lagerung und Erhitzung des Farbbandes verhindern, beispielsweise Cholesterin oder Vanillin, verwendet.As aids e.g. Release agents based on perfluorinated alkylsulfonamidoalkyl esters or silicones, as described in EP-A-227 092 or EP-A-192 435, and especially organic additives which prevent the transfer dyes from crystallizing out when the ink ribbon is stored and heated, for example cholesterol or vanillin used.

Inerte Trägermaterialien sind beispielsweise Seiden-, Lösch- oder Pergaminpapier sowie Folien aus wärmebeständigen Kunststoffen wie Polyestern, Polyamiden oder Polyimiden, wobei diese Folien auch metallbeschichtet sein können.Inert carrier materials are, for example, tissue paper, blotting paper or glassine paper as well as films made of heat-resistant plastics such as polyesters, polyamides or polyimides, these films also being able to be metal-coated.

Der inerte Träger kann auf der dem Thermokopf zugewandten Seite zusätzlich mit einem Gleitmittel beschichtet werden, um ein Verkleben des Thermokopfes mit dem Trägermaterial zu verhindern. Geeignete Gleitmittel sind beispielsweise Silicone oder Polyurethane, wie sie in der EP-A-216 483 beschrieben sind.The inert carrier can additionally be coated with a lubricant on the side facing the thermal head in order to prevent the thermal head from sticking to the carrier material. Suitable lubricants are, for example, silicones or polyurethanes, as described in EP-A-216 483.

Die Stärke des Farbstoffträgers beträgt im allgemeinen 3 bis 30 um, bevorzugt 5 bis 10 um.The thickness of the dye carrier is generally 3 to 30 µm, preferably 5 to 10 µm.

Das zu bedruckende Substrat, z.B. Papier, muß seinerseits mit einem Bindemittel beschichtet sein, welches den Farbstoff beim Druckvorgang aufnimmt. Vorzugsweise verwendet man hierzu polymere Materialien, deren Glasumwandlungstemperatur Tg zwischen 50 und 100°C beträgt, also z.B. Polycarbonate und Polyester. Näheres hierzu ist den EP-A-227 094, EP-A-133 012, EP-A-133 011, JP-A-199 997/1986 oder JP-A 283 595/1986 zu entnehmen.The substrate to be printed, for example paper, must in turn be coated with a binder which absorbs the dye during the printing process. Polymeric materials whose glass transition temperature Tg is between 50 and 100 ° C., for example polycarbonates and polyester, are preferably used for this purpose. Further details can be found in EP-A-227 094, EP-A-133 012, EP-A-133 011, JP-A-199 997/1986 or JP-A 283 595/1986.

Für das erfindungsgemäße Verfahren wird ein Thermokopf eingesetzt, der auf Temperaturen bis über 300 ° C aufheizbar ist, so daß der Farbstofftransfer in einer Zeit von maximal 15 msec erfolgt.For the process according to the invention, a thermal head is used which can be heated to temperatures up to over 300 ° C., so that the dye transfer takes place within a maximum time of 15 msec.

BeispieleExamples

Es wurden zunächst in üblicher Weise Transferblätter (Geber) aus Polyesterfolie von 8 um Stärke hergestellt, die mit einer ca. 5 um starken Transferschicht aus einem Bindemittel B versehen war, welche jeweils 0,25 g Azofarbstoff I enthielt. Das Gewichtsverhältnis Bindemittel zu Farbstoff betrug jeweils 4 : 1.Initially, transfer sheets (donors) were produced in a conventional manner from 8 μm thick polyester film, which was provided with an approximately 5 μm thick transfer layer made of a binder B, which each contained 0.25 g of azo dye I. The weight ratio of binder to dye was 4: 1 in each case.

Das zu bedruckende Substrat (Nehmer) bestand aus Papier von ca. 120 um Stärke, das mit einer 8 um dicken Kunststoffschicht beschichtet war (Hitachi Color Video Print Paper).The substrate (slave) to be printed consisted of paper of approximately 120 μm thick, which was coated with an 8 μm thick plastic layer (Hitachi Color Video Print Paper).

Geber und Nehmer wurden mit der beschichteten Seite aufeinander gelegt, mit Aluminiumfolie umwikkelt und für 2 min zwischen zwei Heizplatten auf eine Temperatur zwischen 70 und 80° C erhitzt. Mit gleichartigen Proben wurde dieser Vorgang dreimal bei jeweils höherer Temperatur zwischen 80 und 120 ° C wiederholt.The coated side of the encoder and slave was placed on top of one another, wrapped with aluminum foil and heated to a temperature between 70 and 80 ° C. for two minutes between two heating plates. With similar samples, this process was repeated three times at a higher temperature between 80 and 120 ° C.

Die hierbei in die Kunststoffschicht des Nehmers diffundierte Farbstoffmenge ist proportional der optischen Dichte, die als Extinktion A photometrisch nach dem jeweiligen Erhitzen auf die oben angegebenen Temperaturen bestimmt wurde.The amount of dye diffused into the plastic layer of the receiver is proportional to the optical density, which was determined as absorbance A photometrically after the respective heating to the temperatures given above.

Die Auftragung des Logarithmus der gemessenen Extinktionswerte A gegen die zugehörige reziproke absolute Temperatur ergibt Geraden, aus deren Steigung die Aktivierungsenergie AET für das Transferexperiment zu berechnen ist:

Figure imgb0003
Plotting the logarithm of the measured extinction values A against the associated reciprocal absolute temperature gives straight lines, from the slope of which the activation energy AE T for the transfer experiment can be calculated:
Figure imgb0003

Der Auftragung kann zusätzlich die Temperatur T* entnommen werden, bei der die Extinktion den Wert 1 erreicht, d.h., die durchgelassene Lichtintensität ein Zehntel der eingestrahlten Lichtintensität beträgt. Je kleinere Werte die Temperatur T* annimmt, um so besser ist die thermische Transferierbarkeit des untersuchten Farbstoffs.The temperature T * at which the extinction reaches the value 1 can also be taken from the application, ie the transmitted light intensity is one tenth of the incident light intensity. The smaller the temperature T * , the better the thermal transferability of the investigated dye.

In der folgenden Tabelle sind die bezüglich ihres Thermotransferverhaltens untersuchten Azofarbstoffe I mit den zugehörigen in Methylenchlorid gemessenen Absorptionsmaxima Amax [nm] aufgeführt.The following table shows the azo dyes I investigated with regard to their thermal transfer behavior with the associated absorption maxima A max [nm] measured in methylene chloride.

Zudem ist das jeweils verwendete Bindemittel B angegeben. Dabei bedeutet: EC = Ethylcellulose, PVB = Polyvinylbutyrat, MS = EC:PVB = 2:1.In addition, the binder B used in each case is indicated. Here means: EC = ethyl cellulose, PVB = polyvinyl butyrate, MS = EC: PVB = 2: 1.

Weiterhin aufgelistete charakteristische Daten sind die bereits erwähnten Parameter T* [ ° C] und AET -[kcal/mol].

Figure imgb0004
Characteristic data also listed are the parameters T * [° C] and AE T - [kcal / mol] already mentioned.
Figure imgb0004

Claims (3)

1. The use in thermal transfer printing of azo dyes of the general formula I
Figure imgb0011
in which the substituents have the following meanings:
R1 is hydrogen, amino, hydroxyl or C1-C3-alkyl,
R2 is hydrogen, acetyl, carbamoyl or cyano,
R3 is ω-phenoxy-, ω-tolyloxy-, ω-benzyloxy- or ω-cyclohexyloxy-C1-C12 2-alkyl whose carbon chain may be interrupted by one or two of the following nonadjacent members: -O-, -CO-, -O-CO- or -CO-O-and which may carry one or two of the following substituents: halogen, hydroxyl, C1-C2-alkyl, phenyl or cyclohexyl,
R4 and R5 are each hydrogen, halogen, cyano, nitro, trihalomethyl or a radical of the formula -CO-H, -CO-R6, -O-CO-R6 , -CO-OR6, -SO-OR6 , -O-SO-OR6 , -CO-NR7R8, -O-CO-NR7R8, -S02-NR7R8 or -0-S02-NR7R8 where R6 is C1-C12-alkyl or ω-phenoxy-, ω-tolyloxy-, ω-benzyloxy- or ω-cyclohexyloxy-C1-C12-alkyl, in each of which (unsubstituted as well as ω-substituted alkyl) the carbon chain may be interrupted by one or two oxygen atoms in ether function, R7 is C1-C12-alkyl, and R8 is hydrogen or has one of the meanings of R7.
2. A process for transferring azo dyes by diffusion from a transfer to a plastic-coated medium with the aid of a thermal printing head, which comprises using for this purpose a transfer on which there is or are one or more azo dyes of the formula I as shown in claim 1.
3. A process as claimed in claim 2, wherein the azo dye used has the formula la
Figure imgb0012
in which the substituents have the following meanings:
R3' is ω-phenoxy-, ω-tolyloxy-, ω-benzyloxy- or ω-cyclohexyloxy-C1-C12-alkyl whose carbon chain may be interrupted by one or two oxygen atoms in ether function,
R4' and R5' are each hydrogen, chlorine, cyano or a radical of the formula
Figure imgb0013
EP91109225A 1990-06-19 1991-06-06 Use of azo dyes in thermal transfer printing Expired - Lifetime EP0462447B1 (en)

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US6835708B2 (en) 2001-03-07 2004-12-28 Nippon Shokubai Co., Ltd. Graft polymer composition and its production process and uses
JP5634019B2 (en) * 2008-10-14 2014-12-03 キヤノン株式会社 Dye compound and ink containing the dye compound
CN105504858A (en) * 2016-01-27 2016-04-20 杭州福莱蒽特精细化工有限公司 Single azo based pyridine ketone dye and preparation method and application thereof

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