DE4139684A1 - Thermotransfer printing plates for colour photography etc. - have substrate with layer contg. thiadiazolyl:azo dyestuff with good solubility inorganic solvent and stability - Google Patents

Abstract

Thermotransfer printing plates have a substrate on which is a layer contg. a thiadiazolylazo-dye of formula (I). In (I) R1 and R2 each = opt. substd. by halogen, hydroxy or cyano gps., or interrupted by O at least 12C-alkyl gps., cycloalkyl gps., or phenyl or phenyl-1-3C-alkyl gps. opt. ring-substd. by halogen, cyano, lower alkyl, lower alkoxy, lower alkoxycarbonyl or lower alkylcarbonyl gps.; X = lower alkyl or -NH-1-8C-acyl; Y = H, halogen, lower alkyl or lower alkoxy, and Z = phenyl-1-3C-alkyl opt. ring substd. by halogen, cyano, lower alkyl, lower alkoxy, lower alkylcarbonyl or lower alkoxycarbonyl. Pref. R1 and R2 = lower alkyl; X = -NH-2-8C-acyl, where acyl = lower alkylcarbonyl or acetyl; Y = H and Z = benzyl, phenylethyl or phenylisopropyl. USE/ADVANTAGE - The dyestuff may be transferred using a thermal head, useful in the thermodiffusion transfer process (D2T2) for colour photography, videocameras, and televisions. The dyestuff exhibits good solubility in organic solvents, it is thermally transferable using reduced time and energy, enhanced migration-fastness and photochemical stability at room temp., and enhanced light-fastness and picture stability against chemicals, moisture and friction.

Description

The invention relates to a thermal transfer printing sheet, which thiadiazolylazo dyes contains, which can be transferred by diffusion using a thermal head. Among the z. Currently available color copying or color printing processes impress the thermo Diffusion transfer process (D2T2) through excellent, classic color photography very close image quality. From various image sources, such as B. Video cameras or screens of computers and televisions, supplied and ge if necessary, storable on modern data carriers and via telecommunication networks Transferable digital raster image information can be formatted using D2T2 technology a corresponding full-color hard copy on opaque and transparent substrates be issued.

The D2T2 process consists of three main components, known as the donor (dye-releasing carrier), thermal head and acceptor (dye-receiving image carrier) can be. The band-like donor contains one on its front Color layer, in the areas in the ribbon direction one after the other with a dye each subtractive primary colors yellow, magenta and cyan (and possibly also black) are included. Depending on the format, the thermal head is up to about 30 cm long 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 absorb dye released by the donor.

In order to generate an image, a color area of the Donors placed on the dye-receiving layer of the acceptor. The desired Image 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 supplied amount of heat controlled. With a suitable feed mechanism the raster image information contained in the color separation line by line onto the acceptor  transfer material. After the corresponding donor band transport, the two (in In the case of an additional black area, the three) other color separations in the same way transferred.

To enable optimal color recording, the D2T2 process should be used 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 and matched to the other trichromatic components as well Image stability against the effects of chemicals, moisture and friction.

The object of the present invention was to provide a thermal transfer printing sheet, which is particularly suitable for the D2T2 process and where the dyes are the above should have the specified properties.

A thermal transfer printing sheet has now been found, which is red thiadiazolylazo contains dyes that can meet the above requirements as well as possible and whereby the transfer of the dyes by diffusion using a thermal head well done according to the D2T2 method.

The present invention relates to a thermal transfer printing sheet with a substrate, which carries a layer containing a thiadiazolylazo dye of the general formula

contains what
R₁ and R₂, independently of one another, each unsubstituted or substituted by halogen, hydroxyl or cyano or interrupted by oxygen atoms, alkyl having at most 12 carbon atoms, cycloalkyl or unsubstituted or by halogen, cyano, lower alkyl, lower alkoxy, lower alkoxycarbonyl or lower alkylcarbonyl ring-substituted phenyl or phenyl-C₁ -C₃-alkyl,
X lower alkyl or -NH-C₁-C₈-alkyl,
Y is hydrogen, halogen, lower alkyl or lower alkoxy and
Z is phenyl-C₁-C₃-alkyl which is unsubstituted or ring-substituted by halogen, cyano, lower alkyl, lower alkoxy, lower alkyl carbonyl or lower alkoxycarbonyl.

Mixtures of these dyes or mixtures with other transferable ones can also be used Dyes are used.

Lower alkyl and lower alkoxy generally represent such groups or group components represent, which have 1 to 6, in particular 1 to 4 carbon atoms, such as. B. methyl, Ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec. Butyl, amyl, isoamyl or hexyl or Methoxy, ethoxy, isopropoxy, isobutoxy, tert. Butoxy or amyloxy.

Halogen in connection with all the above and below substituents means for example fluorine, bromine or preferably chlorine.

Are the substituents R₁ and R₂ alkyl groups, they can be straight-chain or be branched. Examples of such alkyl radicals are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec. Butyl, amyl, isoamyl, 2-ethylbutyl, n-hexyl, 2-ethylhexyl, n-octyl, isooctyl, nonyl or dodecyl.

Are the alkyl radicals R₁ and R₂ substituted, it is mainly cyanoalkyl, Haloalkyl and hydroxyalkyl with a total of 2 to 6 carbon atoms, such as. B. 2-cyanoethyl, 2-chloroethyl, 2-hydroxyethyl, 2-hydroxy-3-chloropropyl.

The alkyl radicals R₁ and R₂ can also be interrupted by 1 to 3 oxygen atoms. Examples of such radicals are 2-methoxyethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-isopropoxyethyl, 2-butoxyethyl, 2-methoxypropyl, 3-methoxypropyl, 4-ethoxybutyl, 4-propoxybutyl, 3,6-dioxaoctyl, 4,7-dioxaoctyl, 3,6,9-trioxadecyl or 3,6,9-trioxaundecyl.

Preferably R₁ and R₂ each represent lower alkyl.  

Examples of cycloalkyl in the meaning of the R radicals are cyclopentyl and cycloheptyl or preferably cyclohexyl. The cycloalkyl radicals can have one or more C₁-C₄ alkyl radicals, preferably methyl groups, contain and have a total of 5 to 10 carbon atoms.

Preferred substituents in the phenyl group of R₁ and R₂ are e.g. B. halogen, cyano, Methyl, methoxy or carbomethoxy. For example, R₁ and R₂ can be chlorophenyl, Methoxyphenyl, tolyl, xylyl, 2,6-dimethylphenyl or carbomethoxyphenyl mean.

R₁ and R₂ in the meaning of phenylalkyl radicals are usually phenylethyl, Phenylisopropyl or especially for benzyl. These aralkyl radicals can be replaced by halogen, Cyano, lower alkyl, lower alkoxy, lower alkoxycarbonyl or lower alkylcarbonyl be substituted. Examples of such araliphatic radicals are methylbenzyl, 2,4- or 2,5-dimethylbenzyl, chlorobenzyl, dichlorobenzyl or cyanobenzyl.

X is preferably the group -NH-acyl.

"Acyl" is especially formyl or lower alkylcarbonyl, such as. B. acetyl, propionyl or Butyryl, or benzoyl. Other acyl radicals can be lower alkylsulfonyl, such as. B. Be methylsulfonyl, ethylsulfonyl and phenylsulfonyl. Lower alkylcarbonyl as well Lower alkyl sulfonyl can contain halogen, hydroxy or lower alkoxy. Benzoyl and Phenylsulfonyl can be substituted by halogen, methyl, methoxy or ethoxy. "Acyl" is preferably lower alkylcarbonyl and especially acetyl.

Y is preferably hydrogen.

Z expediently stands for phenylethyl, phenylisopropyl or primarily for Benzyl. The benzene ring can be replaced by halogen, trifluoromethyl, cyano, lower alkyl, Lower alkoxy, lower alkoxycarbonyl or lower alkylcarbonyl may be substituted. R₂ and Z can be identical.

Particularly important, thermally transferable dyes correspond to the formula  

wherein
R₃, R₄ and T, independently of one another, each lower alkyl, halogen-lower alkyl, cyano-lower alkyl or lower alkoxy-lower alkyl,
Q is C₁-C₃-alkylene and Y₁ is hydrogen or methyl and the ring A is unsubstituted or substituted by halogen, lower alkyl or lower alkoxy.

Among these dyes of the formula (2), those are particularly preferred in which R₃, R₄ and T₁ each represent lower alkyl, Q-CH₂-, Y₁ hydrogen and the ring A phenyl, chlorophenyl, tolyl, xylyl or methoxyphenyl.

The thiadiazolylazo dyes of the formulas (1) and (2) used according to the invention are known in part from US-A-3639384 or can according to those described there Processes are made. A process for the preparation of the dyes Formulas (1) and (2) consist in that an amine of the formula

diazotized and then the diazonium salt with a compound of the formula

couples, wherein R₁, R₂, X, Y and Z have the meaning given.

The colors are used to produce the thermal transfer printing sheet according to the invention  substances suitably in a suitable solvent, e.g. B. benzene, chlorobenzene, Toluene, cyclohexanone, ethyl methyl ketone, methyl isobutyl ketone, ethanol, propanol, Isopropanol, isobutanol, tetrahydrofuran or mixtures thereof with one or several binders, optionally with the addition of auxiliaries, to one Printing ink processed. The printing ink is applied to an inert by means of a squeegee (coater) Substrate, which serves as a dye carrier, applied, after which the layer obtained z. B. on air dried.

Suitable binders are advantageously polymers which are in organic form 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, polyvinyl acetal, polyvinyl acetate, polyvinyl butyral, polyvinyl butyrate, polyvinyl pyrrolidone, cellulose derivatives such as e.g. 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, polymethylacrylates, 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 consisting of paper, such as tissue paper or blotting paper, can also be used as a carrier 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-216 483 or EP-A-227 095. 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 Is thermally transferred using a thermal head. 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 dyes to be transferred into consideration. The glass transition temperature these plastics should be below 150 ° C. Resins are exemplary Basis of polyacrylates, polycarbonates, polyamides, polycaprolactones, polyvinyl chloride, polyurethanes or preferably polyesters and also stylol maleic acid to name anhydride copolymers.

In the following examples, the percentages given refer to if nothing otherwise specified is by weight. Parts are parts by weight.

example 1

0.4 g of the dye of the formula

are made from the same in 10 g of a 4% w / g polyvinyl butyral containing binder Parts by weight of toluene and ethyl methyl ketone existing mixture dissolved at 20 ° C. and by means of a doctor blade onto a 6 μ thick polyester film in a nominal 12 μ thick Layer applied. The coated polyester film is used as a donor in a video Printer used. After dye transfer to original Hitachi Color Video Print  Paper results in a brilliant red full-surface print with a reflection density OD = 2.0. The resulting with a xenon exposure apparatus after 50 hours of irradiation relative loss of density is 5%. The dye is characterized by a very high specific extinction coefficients of 120,000 cm² / g.

If the same amount of a is used in Example 1 instead of the dye of the formula (11) of the dyes of the formula given in the table

so you get a red full-surface print with similarly good results.  

table

Claims (10)

1. Thermal transfer printing sheet with a substrate bearing a layer containing a thiadiazolylazo dye of the formula contains what
R₁ and R₂, independently of one another, each unsubstituted, substituted by halogen, hydroxy or cyano or interrupted by oxygen atoms, alkyl having at most 12 carbon atoms, cycloalkyl or unsubstituted or ring-substituted phenyl or phenyl or phenyl-C₁ by halogen, cyano, lower alkyl, lower alkoxy, lower alkoxycarbonyl or lower alkylcarbonyl -C₃-alkyl,
X lower alkyl or -NH-C₁-C₈ acyl,
Y is hydrogen, halogen, lower alkyl or lower alkoxy and
Z is phenyl-C₁-C₃-alkyl which is unsubstituted or ring-substituted by halogen, cyano, lower alkyl, lower alkoxy, lower alkyl carbonyl or lower alkoxycarbonyl. 2. Thermal transfer printing sheet according to claim 1, characterized in that in Formula (1) R₁ and R₂ each represent lower alkyl. 3. Thermal transfer printing sheet according to one of claims 1 and 2, characterized in that that in formula (1) X is -NH-C₂-C₈-acyl. 4. Thermal transfer printing sheet according to claim 3, characterized in that "acyl" Lower alkylcarbonyl and especially acetyl means. 5. Thermal transfer printing sheet according to one of claims 1 to 4, characterized in that in formula (1) Y is hydrogen. 6. Thermal transfer printing sheet according to one of claims 1 to 5, characterized in  net that in formula (1) Z means benzyl, phenylethyl or phenylisopropyl. 7. Thermal transfer printing sheet according to claim 1, characterized in that it is a thiadiazolylazo dye of the formula contains what
R₃, R₄ and T, independently of one another, each lower alkyl, halogen-lower alkyl, cyano-lower alkyl or lower alkoxy-lower alkyl,
Q is C₁-C₃-alkylene and Y₁ is hydrogen or methyl and the ring A is unsubstituted or substituted by halogen, lower alkyl or lower alkoxy. 8. Thermal transfer printing sheet according to claim 7, characterized in that in Formula (2) R₃, R₄ and T each lower alkyl, Q -CH₂-, Y₁ hydrogen and the ring A phenyl, Chlorophenyl, tolyl, xylyl or methoxyphenyl mean. 9. Use of a thiadiazolylazo dye of the formula wherein
R₁ and R₂, independently of one another, each unsubstituted, substituted by halogen, hydroxy or cyano or interrupted by oxygen atoms, alkyl having at most 12 carbon atoms, cycloalkyl or unsubstituted or ring-substituted phenyl or phenyl-C₁- by halogen, cyano, lower alkyl, lower alkoxy, lower alkoxycarbonyl or lower alkylcarbonyl C₃-alkyl,
X lower alkyl or -NH-C₁-C₈ acyl,
Y is hydrogen, halogen, lower alkyl or lower alkoxy and
Z is unsubstituted or halogen-substituted by halogen, cyano, lower alkyl, lower alkoxy, lower alkyl carbonyl or lower alkoxycarbonyl, phenyl-C₁-C₃-alkyl, for the thermal transfer printing process. 10. A method for transferring dyes from a support to a recording material by diffusion with the aid of a thermal head, characterized in that a thermal transfer printing sheet is used which comprises a thiadiazolylazo dye of the formula contains, wherein R₁ and R₂, independently of one another, each unsubstituted, substituted by halogen, hydroxy or cyano or interrupted by oxygen atoms, alkyl having at most 12 carbon atoms, cycloalkyl or unsubstituted or ring-substituted phenyl or phenyl by halogen, cyano, lower alkyl, lower alkoxy, lower alkoxycarbonyl or lower alkylcarbonyl -C₁-C₃-alkyl,
X lower alkyl or -NH-C₁-C₈ acyl,
Y is hydrogen, halogen, lower alkyl or lower alkoxy and
Z is phenyl-C₁-C₃-alkyl which is unsubstituted or ring-substituted by halogen, cyano, lower alkyl, lower alkoxy, lower alkyl carbonyl or lower alkoxycarbonyl.