EP0509302B1 - Process for transfer of methine dyes - Google Patents

Description

The present invention relates to a new method for transferring methine dyes from a support to a plastic-coated paper using an energy source.

In the thermal transfer printing process, a transfer sheet, which contains a thermally transferable dye in one or more binders, optionally together with suitable auxiliaries, on a support, with an energy source, e.g. with a heating head or a laser, heated by short heating impulses (duration: fractions of a second) from the back, whereby the dye migrates from the transfer sheet and diffuses into the surface coating of a recording medium. 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 released from the energy source.

In general, the color recording is carried out using the three subtractive primary colors yellow, magenta, cyan (and possibly black).

• leichte thermische Transferierbarkeit,
• geringe Migration innerhalb oder aus der Oberflächenbeschichtung des Aufnahmemediums bei Raumtemperatur,
• hohe thermische und photochemische Stabilität sowie Resistenz gegen Feuchtigkeit und chemische Stoffe,
• für subtraktive Farbmischung die geeigneten Farbtöne aufweisen,
• einen hohen molaren Absorptionskoeffizienten aufweisen,
• bei Lagerung des Transferblattes nicht auskristallisieren.

In order to enable optimal color recording, the dyes must have the following properties:

• easy thermal transferability,
• low migration 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 chemical substances,
• have the appropriate shades for subtractive color mixing,
• have a high molar absorption coefficient,
• do not crystallize out when storing the transfer sheet.

Experience has shown that these requirements are very difficult to meet at the same time.

Therefore, most of the known dyes used for thermal transfer printing, in particular those which have the basic color magenta, do not meet the required profile of requirements.

For example, described in JP-A-229 786/1985, JP-A-84 390/1990 and in EP-A-258 856 aniline derivatives for this purpose, which have the tricyanovinyl radical in the para position to the amino group. JP-A-32 164/1990 describes dyes which have 4-nitrophenylacetonitrile as a CH-acidic component. EP-A-279 467 describes the transfer of dyes whose CH-acidic components are benzoylacetonitrile and its halogenated derivatives.

However, it has been shown that sufficient results are not achieved with these dyes.

It was therefore an object of the present invention to provide a new method for the transmission of methine dyes with absorption in the blue-green or green spectral range, the dyes used having the properties mentioned at the outset.

K

für einen Rest der Formel

worin

n

0 oder 1,

R¹

Wasserstoff, Methyl, Methoxy, C₁-C₄-Mono- oder Dialkylaminosulfonylamino, C₁-C₄-Alkylsulfonylamino oder den Rest -NHCOR⁹ oder NHCO₂R⁹, wobei R⁹ die Bedeutung von Phenyl, Benzyl, Tolyl oder C₁-C₈-Alkyl, das gegebenenfalls durch ein oder zwei Sauerstoffatome in Etherfunktion unterbrochen ist, besitzt,

R²

Wasserstoff, Methyl, Methoxy oder Ethoxy,

R³ und R⁴

gleich oder verschieden sind und unabhängig voneinander jeweils Wasserstoff, C₁-C₈-Alkyl, das gegebenenfalls substituiert ist und durch ein oder zwei Sauerstoffatome in Etherfunktion unterbrochen sein kann, oder C₅-C₇-Cycloalkyl,

R⁵

C₁-C₈-Alkyl, das gegebenenfalls substituiert ist und durch ein oder zwei Sauerstoffatome in Etherfunktion unterbrochen sein kann, C₅-C₇-Cycloalkyl, Phenyl oder Tolyl,

R⁶

Wasserstoff, Halogen, C₁-C₆-Alkyl, gegebenenfalls durch C₁-C₄-Alkyl oder C₁-C₄-Alkoxy substituiertes Phenyl, gegebenenfalls durch C₁-C₄-Alkyl oder C₁-C₄-Alkoxy substituiertes Benzyl, Cyclohexyl, Thienyl, Hydroxy oder C₁-C₈-Monoalkylamino,

R⁷

Cyano, Carbamoyl, C₁-C₆-Mono- oder Dialkylcarbamoyl oder C₁-C₆-Alkoxycarbonyl und

R⁸

Halogen, Wasserstoff, C₁-C₄-Alkyl, C₁-C₄-Alkoxy, C₁-C₄-Alkylthio oder gegebenenfalls durch C₁-C₄-Alkyl substituiertes Phenyl bedeuten, und

B

für den Rest einer CH-aciden Verbindung stehen, der sich von Nitromethan, Nitroethan, Benzimidazolen-2-ylacetamid oder einer Verbindung der Formel

ableitet, worin

X¹

Cyano, Nitro, C₁-C₄-Alkanoyl, C₁-C₄-Alkylsulfonyl,
gegebenenfalls durch C₁-C₄-Alkyl, C₁-C₄-Alkoxy oder Halogen substituiertes Phenylsulfonyl, Carboxyl, gegebenenfalls durch 1 oder 2 Sauerstoffatome in Etherfunktion unterbrochenes C₁-C₆-Alkoxycarbonyl, C₅-C₇-Cycloalkoxycarbonyl, gegebenenfalls durch C₁-C₄-Alkyl, C₁-C₄-Alkoxy oder Halogen substituiertes Phenoxycarbonyl, Carbamoyl, gegebenenfalls durch 1 oder 2 Sauerstoffatome in Etherfunktion unterbrochenes C₁-C₆-Mono- oder Dialkylcarbamoyl, C₅-C₇-Mono- oder Dicycloalkylcarbamoyl, gegebenenfalls durch C₁-C₄-Alkyl, C₁-C₄-Alkoxy oder Halogen substituiertes Phenylcarbamoyl, Benzthiazol-2-yl, 5-Phenyl-1,3,4-thiadiazol-2-yl oder 2-Hydroxychinoxalin-3-yl,

X²

C₁-C₄-Alkyl oder C₁-C₄-Alkoxy,

X³

C₁-C₄-Alkoxycarbonyl, Phenylcarbamoyl oder Benzimidazol-2-yl,

X⁴

C₁-C₄-Alkyl und

X⁵

Wasserstoff, C₁-C₄-Alkyl oder Phenyl bedeuten.

It has now been found that the transfer of methine dyes from a support onto plastic-coated paper with the aid of an energy source is advantageously achieved when using a support on which one or more dyes of the formula I

KN = B (I)

are in the

K

for a rest of the formula

wherein

n

0 or 1,

R ¹

Hydrogen, methyl, methoxy, C ₁ -C ₄ -mono- or dialkylaminosulfonylamino, C ₁ -C ₄ -alkylsulfonylamino or the radical -NHCOR ⁹ or NHCO ₂ R ⁹ , where R ^{9 is} phenyl, benzyl, tolyl or C ₁ -C ₈ alkyl, which is optionally interrupted by one or two oxygen atoms in ether function,

R ²

Hydrogen, methyl, methoxy or ethoxy,

R ³ and R ⁴

are identical or different and are each independently hydrogen, C ₁ -C ₈ -alkyl, which is optionally substituted and can be interrupted by one or two oxygen atoms in ether function, or C ₅ -C ₇ -cycloalkyl,

R ⁵

C ₁ -C ₈ alkyl, which is optionally substituted and can be interrupted by one or two oxygen atoms in ether function, C ₅ -C ₇ cycloalkyl, phenyl or tolyl,

R ⁶

Hydrogen, halogen, C ₁ -C ₆ alkyl optionally substituted by C ₁ -C ₄ alkyl or C ₁ -C ₄ alkoxy substituted phenyl, optionally substituted by C ₁ -C ₄ alkyl or C ₁ -C ₄ -alkoxy-substituted Benzyl, cyclohexyl, thienyl, hydroxy or C ₁ -C ₈ monoalkylamino,

R ⁷

Cyano, carbamoyl, C ₁ -C ₆ mono- or dialkylcarbamoyl or C ₁ -C ₆ alkoxycarbonyl and

R ⁸

Halogen, hydrogen, C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy, C ₁ -C ₄ alkylthio or phenyl optionally substituted by C ₁ -C ₄ alkyl, and

B

stand for the rest of a CH-acidic compound, which is derived from nitromethane, nitroethane, benzimidazolen-2-ylacetamide or a compound of the formula

derives what

X ¹

Cyano, nitro, C ₁ -C ₄ alkanoyl, C ₁ -C ₄ alkylsulfonyl,
phenylsulfonyl, carboxyl optionally substituted by C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy or halogen, C ₁ -C ₆ alkoxycarbonyl, C ₅ -C ₇ cycloalkoxycarbonyl optionally interrupted by 1 or 2 oxygen atoms in ether function, if appropriate C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy or halogen substituted phenoxycarbonyl, carbamoyl, optionally interrupted by 1 or 2 oxygen atoms in ether function, C ₁ -C ₆ mono- or dialkylcarbamoyl, C ₅ -C ₇ mono - or dicycloalkylcarbamoyl, optionally substituted by C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy or halogen, phenylcarbamoyl, benzthiazol-2-yl, 5-phenyl-1,3,4-thiadiazol-2-yl or 2- Hydroxyquinoxalin-3-yl,

X ²

C ₁ -C ₄ alkyl or C ₁ -C ₄ alkoxy,

X ³

C ₁ -C ₄ alkoxycarbonyl, phenylcarbamoyl or benzimidazol-2-yl,

X ⁴

C ₁ -C ₄ alkyl and

X ⁵

Is hydrogen, C ₁ -C ₄ alkyl or phenyl.

All alkyl groups occurring in the above formulas can be both straight-chain and branched.

If substituted alkyl or phenyl groups occur in the formulas mentioned above, these are generally mono- to trisubstituted.

If substituted alkyl groups occur in the above formulas, the substituents can be, for example, cyano, phenyl, tolyl, C ₁ -C ₆ alkanoyloxy, C ₁ -C ₄ alkoxycarbonyl or C ₁ -C ₄ alkoxycarbonyloxy, in the latter case the alkoxy group may be substituted by phenyl, tolyl or C ₁ -C ₄ alkoxy.

Suitable radicals X ² , X ⁴ , X ⁵ , R ³ , R ⁴ , R ⁶ and R ⁸ are, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl or sec-butyl.

R ³ , R ⁴ and R ⁶ are furthermore, for example, pentyl, isopentyl, neopentyl, tert-pentyl, hexyl or 2-methylpentyl.

R ³ and R ⁴ are furthermore, for example, heptyl, octyl, 2-ethylhexyl, 2-methoxyethyl, 2- or 3-methoxypropyl, 2-ethoxyethyl, 2- or 3-ethoxypropyl, 2-propoxyethyl, 2- or 3-propoxypropyl, 2-butoxyethyl, 2- or 3-butoxypropyl, 3,6-dioxaheptyl, 3,6-dioxaoctyl, 2-cyanoethyl, 2- or 3-cyanopropyl, 2-acetyloxyethyl, 2- or 3-acetyloxypropyl, 2-isobutyryloxyethyl, 2- or 2-isobutyryloxypropyl, 2-methoxycarbonylethyl, 2- or 3-methoxycarbonylpropyl, 2-ethoxycarbonylethyl, 2- or 3-ethoxycarbonylpropyl 2-methoxycarbonyloxyethyl, 2- or 3-methoxycarbonyloxypropyl, 2-ethoxycarbonyloxyethyl, 2- or 3-ethoxycarbonyloxypropyl, 2-butoxycarbonyloxyethyl, 2- or 3-butoxycarbonyloxypropyl, 2- (2-phenylethoxycarbonyloxy) ethyl, 2- or 3- (2-phenylethoxycarbonyloxy) propyl, 2- ( 2-ethoxyethoxycarbonyloxy) ethyl, 2- or 3- (2-ethoxyethoxycarbonyloxy) propyl, benzyl, 2-methylbenzyl, 1- or 2-phenylethyl, cyclopentyl, cyclohexyl or cycloheptyl.

Residues X ² and R ⁸ are furthermore, for example, methoxy, ethoxy, propoxy, iospropoxy, butoxy, sec-butoxy, methylthio, ethylthio, propylthio, isopropylthio or butylthio.

R ⁸ radicals are furthermore, for example, fluorine, chlorine or bromine.

R ¹ radicals are, for example, methylsulfonylamino, ethylsulfonylamino, propylsulfonylamino, isopropylsulfonylamino, butylsulfonylamino, mono- or dimethylaminosulfonylamino, mono- or diethylaminosulfonylamino, mono- or dipropylamino-nylamino, mono- or di-mono-aminylamino, mono- or di-mono-aminylamino, mono- or di-mono-aminylamino, mono- or di-mono-aminylamino, .

Residues X ¹ , X ³ and R ⁷ are, for example, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl or butoxycarbonyl.

Residues X ¹ and R ⁷ are furthermore, for example, pentyloxycarbonyl, hexyloxycarbonyl, mono- or dimethylcarbamoyl, mono- or diethylcarbamoyl, mono- or dipropylcarbamoyl, mono- or diisopropylcarbamoyl, mono- or dibutylcarbamoyl or N-methyl-N-ethylcarbamoyl.

X ¹ radicals are furthermore, for example, 2-methoxyethoxycarbonyl, 2-ethoxyethoxycarbonyl, 3,6-dioxaheptyloxycarbonyl, cyclopentyloxycarbonyl, cyclohexyloxycarbonyl, cycloheptyloxycarbonyl, formyl, acetyl, propionyl, butyryl, isobutyryl,

Methylsulfonyl, ethylsulfonyl, propylsulfonyl, isopropylsulfonyl, butylsulfonyl, phenylsulfonyl, 2- or 4-methylphenylsulfonyl, mono- or dipentylcarbamoyl, mono- or dihexylcarbamoyl, mono- or bis (2-methoxyethyl) carbamoyl, mono- or bis (2) , Mono- or bis (3,6-dioxaheptyl) carbamoyl, mono- or dicyclopentylcarbamoyl, mono- or dicyclohexylcarbamoyl, mono- or dicycloheptylcarbamoyl, Phenylcarbamoyl, 2-methylphenylcarbamoyl, 2,4-dimethylphenylcarbamoyl, 2-methoxyphenylcarbamoyl, 2,4-dimethoxyphenylcarbamoyl, 2-chlorophenylcarbamoyl or 2,4-dichlorophenylcarbamoyl.

A method is particularly preferred in which there are one or more dyes of the formula I on the support, in which B represents the residue of a CH-acidic compound which is derived from a compound of the formula IIa or IIb.

Furthermore, a method is particularly preferred in which there are one or more dyes of the formula I in which K represents a radical of the formula IIIa, IIIc, IIIj, IIIk, IIIl or IIIm.

steht.Of particular note is a process in which one or more dyes of the formula I are on the support, in which B is for the rest of the formula

stands.

The methine dyes of the formula I can be prepared by methods known per se, as described, for example, in JP-A-32 164/1990, in the earlier application EP-A-416 434 or in the earlier German patent application P 41 05 197.1 (EP-A -0 499 822) are produced.

In comparison to the dyes used in the known processes, the dyes of the formula I which are transferred in the process according to the invention are generally distinguished by improved migration properties in the recording medium at room temperature, easier thermal transferability, higher thermal and photochemical stability, easier technical accessibility, better resistance to moisture and chemical substances, higher color strength, better solubility or better suitability for the subtractive color mixture (higher color purity, less blue absorption, more favorable form of the absorption band, eg narrow half-width or greater edge steepness on the short-wave side). In addition, they are particularly advantageous for dye mixtures with red or reddish-violet dyes. Such dyes are for example from EP-A-216 483, EP-A-209 990, EP-A-312 211, US-A-4 698 651, EP-A-346 729 or the earlier applications EP-A-416 434, EP-A-441 208 or EP-A-460 463.

The dyes of the formula I, in combination with violet dyes, produce highly brilliant magenta stains and, in combination with cyan dyes, highly brilliant, reddish blue stains. At the same time, a deep, neutral black is achieved in combination with suitable yellow dyes.

To produce the dye carriers required for the process according to the invention, the dyes are processed into a printing ink in a suitable organic solvent or in mixtures of solvents with one or more binders, if appropriate with the addition of auxiliaries. This contains the dye preferably in a molecularly disperse dissolved form. The printing ink can be applied to the inert support using a doctor blade and the dyeing can be dried in air.

Suitable organic solvents for the dyes I are e.g. those in which the solubility of the dyes I at room temperature is greater than 1% by weight, preferably greater than 5% by weight.

Examples include ethanol, propanol, isobutanol, tetrahydrofuran, methylene chloride, methyl ethyl ketone, cyclopentanone, cyclohexanone, toluene, chlorobenzene or mixtures thereof.

All resins or polymer materials which are soluble in organic solvents and are capable of binding the dye to the inert support in an abrasion-resistant manner are suitable as binders. Preference is given to binders which, after the printing ink has dried in air, absorb the dye in the form of a clear, transparent film without the dye crystallizing out visibly.

Such binders are mentioned, for example, in the earlier application EP-A-441 282 or in the corresponding patent applications cited therein.

Preferred binders are ethyl cellulose, ethyl hydroxyethyl cellulose, polyvinyl butyrate, polyvinyl acetate or saturated linear polyesters.

The weight ratio of binder: dye is generally 1: 1 to 5: 1.

Examples of suitable auxiliaries are release agents, such as those mentioned in the earlier application EP-A-441 282 or the corresponding patent applications cited therein. They are also particularly organic To name additives that prevent the transfer dyes from crystallizing out when the ribbon is stored or heated, for example cholesterol or vanillin.

Suitable inert carriers are e.g. described in the earlier application EP-A-441 282 or in the corresponding patent applications cited therein. The thickness of the dye carrier is generally 3 to 30 microns, preferably 5 to 10 microns.

In principle, all temperature-stable plastic layers with affinity for the dyes to be transferred can be used as the dye-receiving layer, e.g. modified polycarbonate or polyester. Further details can e.g. from the earlier application EP-A-441 282 or the corresponding patent applications cited therein.

The transmission takes place by means of an energy source, e.g. by means of a laser or by means of a thermal head, which must be able to be heated to a temperature of ° 300 ° C. so that the dye transfer can take place in the time range t: 0 <t <15 ms. The dye migrates from the transfer sheet and diffuses into the surface coating of the recording medium.

The following examples are intended to explain the invention in more detail. Unless otherwise stated, percentages relate to weight.

Transfer of methine dyes

• α) Allgemeines Rezept für die Beschichtung der Träger mit Farbstoff:
  1 g Bindemittel wurden in 8 ml Toluol/Ethanol (8:2 v/v) bei 40 bis 50 °C gelöst. Dazu wurde eine Lösung aus 0,25 g Farbstoff in 30 ml Tetrahydrofuran eingerührt und gegebenenfalls von unlöslichem Rückstand abfiltriert. Die so erhaltene Druckpaste wurde mit einer 80 µm Rakel auf eine Polyesterfolie (Dicke: 6 bis 10 µm) abgezogen und mit einem Fön getrocknet.
• β) Prüfung auf thermische Transferierbarkeit
  Die verwendeten Farbstoffe wurden in der folgenden Weise geprüft: Die den zu prüfenden Farbstoff in der Beschichtungsmasse (Vorderseite) enthaltende Polyesterfolie (Geber) wurde mit der Vorderseite auf kommerziell erhältliches Hitachi Color Video Print Paper (Nehmer) gelegt und aufgedrückt. Geber/Nehmer wurden dann mit Aluminiumfolie umwickelt und zwischen zwei beheizten Platten bei verschiedener Temperatur T (im Temperaturintervall 70°C < T < 120°C) erhitzt. Die in die glänzende Kunststoffschicht des Nehmers diffundierte Farbstoffmenge ist proportional der optischen Dichte (= Extinktion A). Letztere wurde photometrisch bestimmt. Trägt man den Logarithmus der im Temperaturintervall zwischen 40 und 110°C gemessenen Extinktion A der angefärbten Nehmerpapiere gegen die zugehörige reziproke absolute Temperatur auf, so erhält man Geraden, aus deren Steigung die Aktivierungsenergie ΔE_T für das Transferexperiment berechnet wird: $${\text{ΔE}}_{\text{T}}\text{= 2,3 · R ·}\frac{\text{ΔlogA}}{\text{Δ}\left[\frac{\text{1}}{\text{T}}\right]}$$
  
  
  Zur vollständigen Charakterisierung wurde aus den Auftragungen zusätzlich die Temperatur T* [°C] entnommen, bei der die Extinktion A der angefärbten Nehmerpapiere den Wert 1 erreicht.

In order to be able to check the transfer behavior of the dyes quantitatively and in a simple manner, the thermal transfer was carried out with large-area heating jaws, the transfer temperature varying in the range from 70 ° C <T <120 ° C and the transfer time being set at 2 minutes.

• α) General recipe for coating the carrier with dye:
  1 g of binder was dissolved in 8 ml of toluene / ethanol (8: 2 v / v) at 40 to 50 ° C. For this purpose, a solution of 0.25 g of dye was stirred into 30 ml of tetrahydrofuran and any insoluble residue was filtered off. The printing paste thus obtained was drawn off onto a polyester film (thickness: 6 to 10 μm) using an 80 μm doctor blade and dried using a hair dryer.
• β) Testing for thermal transferability
  The dyes used were tested in the following way: The dye to be tested in the coating composition (front) containing polyester film (donor) was placed with the front side on commercially available Hitachi Color Video Print Paper (slave) and pressed. The encoder / receiver was then wrapped with aluminum foil and heated between two heated plates at different temperatures T (in the temperature interval 70 ° C <T <120 ° C). The amount of dye diffused into the glossy plastic layer of the receiver is proportional to the optical density (= extinction A). The latter was determined photometrically. If one plots the logarithm of the extinction A of the stained slave papers measured in the temperature interval between 40 and 110 ° C against the associated reciprocal absolute temperature, straight lines are obtained, from the slope of which the activation energy ΔE _T for the transfer experiment is calculated: $${\text{ΔE}}_{\text{T}}\text{= 2.3R}\frac{\text{ΔlogA}}{\text{Δ}\left[\frac{\text{1}}{\text{T}}\right]}$$
  
  
  For complete characterization, the temperature T * [° C] was additionally taken from the plots, at which the extinction A of the colored receiving papers reached the value 1.

The dyes listed in the following table were processed according to α) and the resulting, dye-coated supports according to β) tested for the transfer behavior. The table shows the thermal transfer parameters T * and ΔE _T , the absorption maxima of the dyes λ _max (measured in methylene chloride) and the binders used.

B

= Bindemittel

V

= Vylon® 290 der Fa. Toyobo

The following abbreviations apply:

B

= Binder

V

= Vylon® 290 from Toyobo

Claims (3)

1. A process for transferring a methine dye from a transfer to plastic-coated paper by diffusion with the aid of an energy source, which comprises using a transfer comprising one or more dyes of the formula I
   
           K-N=B     (I)
   
   where

   K   is a radical of the formula

   

   

   where

   n   is 0 or 1,

   R¹   is hydrogen, methyl, methoxy, mono- or di-C₁-C₄-alkylaminosulfonylamino, C₁-C₄-alkylsulfonylamino or the radical -NHCOR⁹ or -NHCO₂R⁹, where R⁹ is phenyl, benzyl, tolyl or C₁-C₈-alkyl which may be interrupted by one or two oxygen atoms in ether function,

   R²   is hydrogen, methyl, methoxy or ethoxy,

   R³ and R⁴   are identical or different and each is independently of the other hydrogen, C₁-C₈-alkyl, which may be substituted and which may be interrupted by one or two oxygen atoms in ether function, or C₅-C₇-cycloalkyl,

   R⁵   is C₁-C₈-alkyl, which may be substituted and which may be interrupted by one or two oxygen atoms in ether function, C₅-C₇-cycloalkyl, phenyl or tolyl,

   R⁶   is hydrogen, halogen, C₁-C₆-alkyl, unsubstituted or C₁-C₄-alkyl- or C₁-C₄-alkoxy-substituted phenyl, unsubstituted or C₁-C₄-alkyl- or C₁-C₄-alkoxy-substituted benzyl, cyclohexyl, thienyl, hydroxyl or C₁-C₈-monoalkylamino,

   R⁷   is cyano, carbamoyl, mono- or di-C₁-C₆-valkylcarbamoyl or C₁-C₆-alkoxycarbonyl, and

   R⁸   is halogen, hydrogen, C₁-C₄-alkyl, C₁-C₄-alkoxy, C₁-C₄-alkylthio or unsubstituted or C₁-C₄-alkyl-substituted phenyl,
   and

   B   is the radical of an acidic CH compound which is derived from nitromethane, nitroethane, benzimidazol-2-ylacetamide or a compound of the formula

   

   where

   X¹   is cyano, nitro, C₁-C₄-alkanoyl, C₁-C₄-alkylsulfonyl, unsubstituted or C₁-C₄-alkyl-, C₁-C₄-alkoxy- or halogen-substituted phenylsulfonyl, carboxyl, C₁-C₆-alkoxycarbonyl, monooxa- or dioxa-C₁-C₆-alkoxycarbonyl, C₅-C₇-cycloalkoxycarbonyl, unsubstituted or C₁-C₄-alkyl-, C₁-C₄-alkoxy- or halogen-substituted phenoxycarbonyl, carbamoyl, mono- or di-C₁-C₆-alkylcarbamoyl, monooxa- or dioxa-mono- or -di-C₁-C₆-alkylcarbamoyl, mono- or di-C₅-C₇-cycloalkylcarbamoyl, unsubstituted or C₁-C₄-alkyl-, C₁-C₄-alkoxy- or halogen-substituted phenylcarbamoyl, 2-benzothiazolyl, 5-phenyl-1,3,4-thiadiazol-2-yl or 2-hydroxyquinoxalin-3-yl,

   X²   is C₁-C₄-alkyl or C₁-C₄-alkoxy,

   X³   is C₁-C₄-alkoxycarbonyl, phenylcarbamoyl or 2-benzimidazolyl,

   X⁴   is C₁-C₄-alkyl, and

   X⁵   is hydrogen, C₁-C₄-alkyl or phenyl.
2. A process as claimed in claim 1, wherein the transfer comprises one or more dyes of the formula I where B is the radical of an acidic CH compound which is derived from a compound of the formula IIa or IIb.
3. A process as claimed in claim 1, wherein the transfer comprises one or more dyes of the formula I where K is a radical of the formula IIIa, IIIc, IIIj, IIIk, IIIl or IIIm.