DE4220731A1 - New 4-(2-acylamido -4-di:alkylamino:phenyl:azo) 3-nitrophenyl alkyl sulphone cpds. - used as red dyestuff in thermal transfer printing esp. by diffusion - Google Patents

Abstract

New 4-(2-acylamido-4-dialkylaminophenylazo) -3-nitro-phenyl alkyl sulphones of formula (I) are used as dyestuffs in thermal transfer printing. R1 = 1-8C alkyl; R2 and R3 are each 1-12C alkyl and together contain a total of 6-14C; R4 = 1-8C alkyl; and R1-4 contain a total of 8-20C. USE/ADVANTAGE - (I) are also claimed for use in printing inks; in plastics films for transfer printing; in thermal transfer printing sheets with a substrate and a coating contg. (I), esp. for diffusion dyeing by thermal transfer (D2T2); and in dyeing. (I) give red copies with the colour strength, lightfastness, diffusibility, solubility and heat stability needed for the D2T2 process, which is used e.g. for making full-colour hard copy from e.g. video cameras, computer and TV screens or digital information. They have very high specific extinction coefft., extremely good transferability and give high optical densities at reduced time and energy consumption.

Description

The invention relates to diphenylazo dyes by diffusion using a Thermal head can be transferred. Among the z. Currently available color copy or The thermal diffusion transfer process (diffusion dyeing by thermal transfer, D2T2) due to excellent, very close to classic color photography upcoming image quality. From various image sources, such as B. video cameras or Screens of computers and televisions, supplied and if necessary on modern data carriers that can be stored and transferred via telecommunication networks digital raster image information can use D2T2 technology in the form of a full color hardcopy can be output on opaque and transparent substrates.

The D2T2 process consists of three main components that act as a donor (dye emitting carrier), thermal head and acceptor (dye-receiving image carrier) can be drawn. The band-like donor contains a color on its front layer, in the areas in the ribbon direction one after the other with a dye of each sub tractive primary colors yellow, magenta and cyan (and possibly also black) are holding. Depending on the shape, the thermal head is up to about 30 cm in length Depending on the resolving power equipped with 5 to 15 micro heating elements / mm. The acceptor consists of carrier material and a special layer that is capable of the Donor donated dye.

In order to generate an image, a color area of the Donors placed on the dye-receiving layer of the acceptor. The desired picture information is provided in the form of the corresponding color separation as a driver signal Heating of the micro heating elements of the thermal head used. By means of contact pressure of the thermal head is used for an intimate contact between donor and acceptor Printing area. The individually controllable micro heating elements heat the donor from the back. The amount of dye to be transferred is varied by varying the led amount of heat controlled. With a suitable feed mechanism, the Raster image information contained in the color separation line by line onto the acceptor material  transfer. After the corresponding donor band transport, the two (in the case of a additional black area, which transfers three) other color separations in the same way.

To enable optimal color recording, use the D2T2 process Bare dyes have the following properties:

• - Technically easily accessible and readily soluble in organic solvents
• - spectrally suitable as a component of a subtractive trichrome
• - Easily thermally transferable with as little time and energy expenditure as possible
• - high fastness to migration and photochemical stability at room temperature before and after the transfer
• - high light fastness, matched to the other trichromatic components, as well Image stability against the effects of chemicals, moisture and friction.

For the D2T2 process, a spectrally suitable red with sufficient is missing Color strength with practical lightfastness, diffusibility, solubility and Heat stability. In addition, dyes with very high specific allow Extinction coefficient and exceptionally good transferability high optical densities with reduced time and energy requirements. Even such Dyes are of particular interest.

Specific diphenylazo dyes have now been found which match the above Can meet requirements well and thereby the transfer of dyes through Diffusion with the help of a thermal head according to the D2T2 process works well.

The present invention therefore relates to diphenylazo dyes of the general formula I.

wherein

R₁ C₁-C₈ alkyl;
R₂ and R₃ independently of one another are C₁-C₁₂-alkyl, the sum of the carbon atoms of R₂ and R₃ being at least 6 and at most 14 carbon atoms;
R₄ C₁-C₈ alkyl;

means with the proviso that the sum of the carbon atoms of the radicals R₁ to R₄ is at least 8 and is at most 20.

Alkyl as a substituent in the radicals R₁, R₂, R₃ and R₄ includes in the context of respective definition range in particular the isomeric alkyls such as methyl, ethyl, n-propyl, i-propyl, n-butyl, sec.-butyl, i-butyl, tert.-butyl and the isomers, branched and unbranched pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl and or dodecyl radicals.

Some of the compounds of the formula I are known azo dyes. The invention relates to the use of the compounds of the formula I as dyes in the D2T2 Process, the new compounds of formula I and process for their preparation.

The compounds of the formula I are preferred in which

R₁ C₁-C₈ alkyl;
R₂ C₂-C₆ alkyl;
R₃ C₄-C₈ alkyl; and
R₄ C₁-C₈ alkyl;

means with the proviso that the sum of the carbon atoms of the radicals R₁ to R₄ at least 10 and at most 18.

Furthermore, the compounds of the formula I are preferred in which

• a) the sum of the carbon atoms of the substituents R₂ and R₃ is 8 to 12;
• b) the sum of the carbon atoms of the substituents R₁ to R₄ is 10 to 15.

The following may be mentioned as substituents for the radical R 1 in particular: methyl, ethyl, n-hexyl and 2-ethylhexyl.

The following may be mentioned in particular as substituents for the radical R₂: methyl, ethyl, n-propyl and n-butyl.

The following may be mentioned in particular as substituents for the radical R₃: n-propyl, n-butyl,  n-hexyl, n-octyl, n-dodecyl and 2-ethylhexyl.

The following may be mentioned in particular as substituents for the radical R₄: methyl, ethyl and n-propyl.

Are particularly preferred
4- (2-acetamido-4-dibutylaminophenylazo) -3-nitro-phenylethyl sulfone and
4- [2-Acetamido-4- (N-ethyl-N-hexylamino) phenylazo] -3-nitro-phenyleth-ylsulfone.

The diphenylazo dyes according to the invention are prepared by one Aniline of formula II

wherein the radical R₁ is as previously defined, diazotized and then the diazonium salt with a compound of formula III

wherein the radicals R₂, R₃ and R₄ are as previously defined, couples.

The diazotization of the anilines of formula II and the combination of the resulting Diazonium salts with the coupling components of formula III are according to the usual methods.

The anilines of formula II and the coupling components of formula III are known or can, analogously to processes known from the literature, from precursors known per se getting produced.

The coupling components of the formula III disubstituted on the nitrogen atom can can be prepared, inter alia, by using an N-monoalkylaniline of the formula IVa  or IVb,

wherein the radicals R₂ to R₄ are as previously defined, with an alkyl halide of the formula Va or Vb implemented according to methods known per se.

Suitable anilines of the formula (II) are, for example:
4-amino-3-nitrophenylethyl sulfone,
4-amino-3-nitrophenylmethylsulfone,
4-amino-3-nitrophenyl (2-ethylhexyl) sulfone,
4-amino-3-nitrophenylhexylsulfone or
4-amino-3-nitrophenylpropylsulfone.

Suitable coupling components of the formula (III) are, for example:
3-dibutylamino-acetanilide,
3- (N-ethyl-N-hexylamino) acetanilide,
3- [N-ethyl-N- (2-ethylhexyl) amino] acetanilide,
3- [N-methyl-N- (2-ethylhexyl) amino] acetanilide,
3- (N-methyl-N-dodecylamino) acetanilide,
3- (N-ethyl-N-octylamino) acetanilide,
3- (N-ethyl-N-butylamino) acetanilide or
3-dipropylaminoacetanilide.

The benzoisothiazolylazo dyes according to the invention are particularly suitable as Transfer dyes for the D2T2 process. However, they can also be used as dispersions dyes in the dyeing of polymeric materials, in particular synthetic fibers,  preferably polyester fibers are used.

The dyes become more expedient for the production of the thermal transfer printing sheet in a suitable solvent, e.g. B. benzene, chlorobenzene, toluene, cyclo hexanone, ethyl methyl ketone, methyl isobutyl ketone, ethanol, propanol, isopropanol, isobu tanol, tetrahydrofuran or mixtures thereof with one or more binders, ge if necessary with the addition of auxiliaries, processed into a printing ink. The pressure ink is applied by means of a squeegee (coater) to an inert substrate that acts as a dye carrier serves, applied, after which the layer obtained z. B. is air dried.

Suitable binders are advantageously polymers which are in orga African solvents are soluble and bind the dye to the substrate in an abrasion-resistant manner capital. Preferred binders are those which follow the dye Absorb drying of the printing ink in the form of a clear and transparent layer and prevent visible crystallization of the dye.

Examples of such binders are polyvinyl alcohol, polyacetal, poly vinyl acetate, polyvinyl butyral, polyvinyl butyrate, polyvinyl pyrrolidone, cellulose derivatives, such as B. methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, Cellulose acetate as well as alginates and starch. Polymers and copolymers of acrylic acid or their derivatives can also be used as binders, such as. B. Poly acrylic acid, polymethacrylic acid, polymethacrylates, polyacrylates or styrene acrylate copolymers.

Preferred binders are ethyl cellulose, hydroxyethyl cellulose or above all Polyvinyl butyral.

The ratio of binder to dye is preferably from 10: 1 to 1: 1.

Organic additives which help the dyes to crystallize out can be used as auxiliaries prevent storage or heating of the ribbon, e.g. B. cholesterol or Vanillin can be used.

Plastic films with good heat resistance, for. B. optionally metal-coated polyamide, polyaramide, polyester, polystyrene, Polypropylene, polysulfone, polycarbonate or polyimide. A substrate made of paper,  such as tissue paper or blotting paper can also be used as a backing material. The Substrate can optionally also be added on the side facing the thermal head coated with a lubricant (slipping layer). This layer prevents one any gluing of the thermal head to the carrier material. Suitable lubricants z. B. in EP-A-02 16 483 or EP-A-02 27 095. The thickness of the as Plastic film required for the dye carrier is generally 3 to 20 μm, preferably 5 up to 10 µm.

The color is recorded using a thermal transfer printing process in which the Dye from the transfer printing sheet on a paper coated with plastic A thermal head is thermally transferred. The dye transfer takes place in the generally in the time range of at most 15 ms at a temperature of the thermal head from ≧ 300 ° C. The dye migrates from the transfer sheet and diffuses into it Coating on the surface of the recording used as a dye receiver materials.

In principle, all temperature-stable plastic layers come as the dye receiver layer with affinity for the transferring dyes. The glass wall The temperature of these plastics should be below 150 ° C. Resins are exemplary Basis of polyacrylates, polycarbonates, polyamides, polycaprolactones, polyvinyl chloride, polyurethanes or preferably polyesters as well as styrene-maleic acid to name anhydride copolymers.

The following examples illustrate the invention. Obtain the percentages given unless otherwise stated, the weight; Parts are parts by weight.

Manufacturing example H1 4- (2-acetamido-4-dibutylaminophenylazo) 3-nitro-phenylethyl sulfone

2.30 g (0.010 mol) of 4-amino-3-nitrophenylethyl sulfone are in 5 ml of 96% sulfur acid at room temperature and then with cooling within 3 1.7 ml of 40% nitrosylsulfuric acid were added dropwise at 18 to 20 ° C. After two hour stirring at 18 to 20 ° C, the diazonium salt solution thus obtained is added dropwise within 15 minutes to a solution of 2.90 g (0.011 mol) stirred at 0-5 ° C 3-dibutylamino-acetanilide in 50 ml acetic acid and 1 ml conc. HCl. After about one  Hour is filtered off, washed with water and dried.

3.13 g of the title compound (Verb. No. 1) of the formula are isolated

as a red-brown powder with a melting point of 140-142 ° C. (absorption maximum in DMF 532 nm; Molar extinction 45 500).

H2 4- [2-acetamido-4- (N-ethyl-N-hexylamino) phenylazo] -3-nitro-phenyleth-ylsulfone

Analogously to Example H1, 3- (N-ethyl-N-hexylamino) acetanilide and 3-di are obtained butylamino-acetanilide in 79% yield the title compound (Verb. No. 2) of the formula

as a brown powder of mp. 109-111 ° C (absorption maximum in DMF 526 nm; Molar extinction 51,000).

Preparation of the starting compounds of the formula III H3 3- (N-ethyl-N-hexylamino) acetanilide

3-ethylaminoacetanilide is mixed with 2 equivalents of 1-bromohexane in the presence of Sodium carbonate heated to 120 ° C for 2 hours. After filtering off the inorganic Fractions and distillation of the excess bromhexane are isolated in quantitative Yield the title compound of the formula  

as a red-brown oil.

The coupling components for the other examples can be used in an analogous manner Implementation of appropriately substituted anilines with alkyl bromides.

The compounds of Table 1 are obtained analogously to the preparation examples:

Table 1

Compounds of the formula

Examples of use A1 transfer printing on paper

0.15 g of the 4- (2-acetamido-4-dibutylaminophenyl) obtainable according to preparation example H1 azo) -3-nitro-phenylethyl sulfone of the formula

are in 10 g of a 4 wt .-% polyvinyl butyral mixture containing as a binder Toluene and ethyl methyl ketone dissolved at about 40 ° C and using a coater to a 6 µm thick Polyester film applied in a nominally 12 µm thick layer.

The polyester film available in this way is used as a donor in a HITACHI VY-50 video printer used. After the color transfer to original HITACHI COLOR VIDEO PRINT PAPER results in a bluish red full-surface print with a reflection density OD = 1.77.

The with a Ci 35A Weather-Ometer Xenon exposure apparatus after 50 hours Be radiation resulting radiation measured relative density loss is 0%. The Dye is characterized by a very high specific extinction coefficient of 105,000 cm² / g.

The dye according to Preparation Example 2 already dissolves at room temperature. The Reflectance density is determined with OD = 2.1.

Claims (25)

1. The use of a compound of formula I. whereinR₁ C₁-C₈ alkyl;
R₂ and R₃ independently of one another are C₁-C₁₂ alkyl, the sum of the carbon atoms of R₂ and R₃ being at least 6 and at most 14 carbon atoms;
R₄ is C₁-C₈-alkyl, with the proviso that the sum of the carbon atoms of the radicals R₁ to R₄ is at least 8 and at most 20 as a dye for thermal transfer printing. 2. The use according to claim 1 of a compound of formula I, wherein R₁ is C₁-C₈ alkyl;
R₂ C₂-C₆ alkyl;
R₃ C₄-C₈ alkyl; and
R₄ is C₁-C₈-alkyl, with the proviso that the sum of the carbon atoms of the radicals R₁ to R₄ is at least 10 and at most 18. 3. The use according to claim 1 or 2 of a compound of formula I, wherein the Sum of the carbon atoms of the substituents R₂ and R₃ is 8 to 12. 4. The use according to claim 1, 2 or 3 of a compound of formula I, wherein the Sum of the carbon atoms of the substituents R₁ to R₄ is 10 to 15. 5. The use according to one or more of claims 1 to 4 of a compound of Formula I, wherein R₁ is methyl, ethyl, n-hexyl or 2-ethylhexyl. 6. The use according to one or more of claims 1 to 5 of a compound of formula I, wherein R₂ is methyl, ethyl, n-propyl or n-butyl.   7. The use according to one or more of claims 1 to 6 of a compound of formula I, wherein R₃ n-propyl, n-butyl, n-hexyl, n-octyl, n-dodecyl or 2-ethylhexyl means. 8. The use according to one or more of claims 1 to 7 of a compound of formula I, wherein R₄ is methyl, ethyl or n-propyl. 9. The use of 4- (2-acetamido-4-dibutylaminophenylazo) -3-nitro-phenylethyl- sulfone or 4- [2-acetamido-4- (N-ethyl-N-hexylamino) phenylazo] -3-nitro-phenyleth-yl- sulfone as a compound of formula I according to claim 1. 10. Diphenylazo dye of the formula I. whereinR₁ C₁-C₈ alkyl;
R₂ and R₃ independently of one another are C₁-C₁₂-alkyl, the sum of the carbon atoms of R₂ and R₃ being at least 6 and at most 14 carbon atoms;
R₄ is C₁-C₈-alkyl, with the proviso that the sum of the carbon atoms of the radicals R₁ to R₄ is at least 8 and at most 20. 11. A compound of formula I according to claim 10, wherein
R₁ C₁-C₈ alkyl;
R₂ C₂-C₆ alkyl;
R₃ C₄-C₈ alkyl; and
R₄ C₁-C₈ alkyl; means, with the proviso that the sum of the carbon atoms of the radicals R₁ to R₄ is at least 10 and at most 18. 12. A compound of formula I, according to claim 10 or 11, wherein the sum of Carbon atoms of the substituents R₂ and R₃ is 8 to 12. 13. A compound of formula I, according to claim 10, 11 or 13, wherein the sum of the Carbon atoms of the substituents R₁ to R₄ is 10 to 15. 14. A compound of formula I, according to one or more of claims 10 to 13, wherein R₁ is methyl, ethyl, n-hexyl or 2-ethylhexyl. 15. A compound of formula I, according to one or more of claims 10 to 14, wherein R₂ is methyl, ethyl, n-propyl or n-butyl. 16. A compound of formula I, according to one or more of claims 10 to 16, wherein R₃ is n-propyl, n-butyl, n-hexyl, n-octyl, n-dodecyl or 2-ethylhexyl. 17. A compound of formula I, according to one or more of claims 10 to 16, wherein R₄ is methyl, ethyl or n-propyl. 18. 4- (2-acetamido-4-dibutylaminophenylazo) -3-nitro-phenylethyl sulfone or 4- [2-Acetamido-4- (N-ethyl-N-hexylamino) phenylazo] -3-nitro-phenyleth-ylsulfo as A compound of formula I according to claim 10. 19. A process for the preparation of a compound of formula I according to any one of claims 10 to 18, characterized in that an aniline of formula II wherein the radical R₁ is as previously defined, diazotized and then the diazonium salt with a compound of formula III wherein the radicals R₂, R₃ and R₄ are as previously defined, couples. 20. The method according to claim 19, characterized in that 4-amino-3-nitrophenyl ethylsulfone, 4-amino-3-nitrophenylmethylsulfone, 4-amino-3-nitrophenyl (2-ethylhexyl) - sulfone, 4-amino-3-nitrophenylhexylsulfone or 4-amino-3-nitrophenylpropylsulfone as Aniline of formula (II) with 3-dibutylamino-acetanilide, 3- (N-ethyl-N-hexylamino) -acetanilide, 3- [N-ethyl-N- (2-ethylhexyl) amino] acetanilide, 3- [N-methyl-N- (2-ethylhexyl) amino] acetate anilide, 3- (N-methyl-N-dodecylamino) acetanilide, 3- (N-ethyl-N-octylamino) acetanilide, 3- (N-ethyl-N-butylamino) acetanilide or 3-dipropylamino-acetanilide as a coupling components of the formula (III). 21. Printing ink containing a compound according to any one of claims 10 to 18 Dye. 22. Plastic film for transfer printing, containing a compound according to one of the Claims 10 to 18 as a dye. 23. Thermal transfer printing sheet with a substrate which contains a layer Compound according to one of claims 10 to 18 as a dye. 24. Process for transferring dyes from a support to a record material by diffusion using a thermal head, characterized in that that one uses a compound according to any one of claims 10 to 18 as a dye. 25. dyeing process, characterized in that a compound according to one of the Claims 10 to 18 used as a dye.