GB1599858A - Wet transfer printing process - Google Patents

Description

(54) WET TRANSFER PRINTING PROCESS (71) We, BAYER AKTIENGESELLSCHAFT, a body corporate organised under the laws of Germany, of Leverkusen, Germany, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a process for carrying out wet transfer printing with the aid of anionic reactive dye-stuffs, which is characterised in that reactive dyestuffs containing a monofluorotriazine reactive group and which have a reaction constant of at least 1x10-2 minute - l at pH 10 and 60"C (compare Venkataraman "The Chemistry of Synthetic Dyes, volume VI, page 352") are used.

These dyestuffs are included in the so-called "cold-dyeing dyes", that is to say dyestuffs which have a particularly high reactivity.

Examples which may be mentioned are monofluorotriazine dyestuffs, such as are described in US Patent Specifications 3,558,620 and 3,558,621, as well as British Patent Specification 1,188,606 and German Offenlegungsschrift (German Published Specification) 2,556,640.

Wet transfer printing itself is generally known (US Patent Specifications 2,911,280 and 3,666,397; German Offenlegungsschriften (German Published Specifications) 2,418,283, 2,406,186, 2,122,805 and 2,333,379; and British Patent Specification 1,284,824.).

In wet transfer printing, a temporary support (preferably paper webs) printed with anionic dyestuffs is brought into close contact with a sheet-like substrate, which has been wetted by wetting liquors beforehand, at 100-120"C, the temporary support is removed and the substrate is optionally rinsed.

The dyestuffs are printed onto the temporary supports (paper, metal foils and the like) in the form of printing inks of the customary composition (solutions or dispersions of the dyestuffs in aqueous media or organic solvcnts containing binders). It goes without saying that when reactive dyestuffs were employed, those solvents and binders which are inert towards these dyestuffs were used. In this case it is also advisable to provide paper temporary supports with a thin coat of silicone beforehand.

The substrates to be printed by the process according to the invention can be in the form of woven fabrics, knitted fabrics, nonwoven fabrics, films and other sheet-like structures consisting of materials which can be dyed with anionic reactive dyestuffs.

Such materials are. above all, cellulose materials (cotton, viscose and linen), and natural and synthetic polyamides (wool, silk, polyamide 6 and polyamide 6,6 inter alia). Cellulose materials are preferred, especially cotton.

The time of contact between the temporary support and substrate is 30 to 120 seconds at 100-120"C.

The reaction rate between the dyestuff and the OH groups of cellulose can be increased to a certain extent by increasing the alkalinity of the wetting liquor, which usually contains the alkali required for fixing. However, the tendency of cellulose fibres to yellow with increasing alkalinity under the action of heat restricts the addition of alkali (a maximum of about 30 g of calcined sodium carbonate/litre).

Suitable sources of alkali which can be added to the wetting liquor are, for example, sodium bicarbonate, sodium carbonate, trisodium phosphate, sodium trichloroacetate, sodium methylate and ethylene carbonate, inter alia, or their mixtures.

Furthermore, substantially higher colour yields are achieved if electrolytes, preferably those with monovalent or divalent anions, are added to the wetting liquor or to the printing paste used for printing the temporary support, or if the temporary support is treated, before printing, with formulations which contain such electrolytes.

Suitable electrolytes are, for example, sodium chloride and sodium sulphate decahydrate.

A noteworthy advantage of the process according to the invention compared with previously known wet transfer processes with reactive dyestuffs is that high colour yields can be achieved even without after-fixing by steam or dry heat.

Example 1 a) Printing paste (aqueous): Dyestuff according to British Patent Specification 1,188,606, Example 31 50 g Urea 50 g Na alginate/water 900 g 1000 g b) Wetting liquor (as an emulsion): 4% strength aqueous solution of Na alginate 100 g Water 690 g Emulsifier based on oxyethylated hydroxy diphenyl 10 g White spirit 200 g Calcined sodium carbonate 20 g The temporary support is printed with the colour paste la) and dried.

The cotton to be dyed is padded with the wetting liquor lb) (liquor pick-up 150 So) and brought into contact, without intermediate drying, with the printed temporary support in a press at 105"C under a pressure of 4 bars for 1 minute.

After leaving the press, the temporary support is removed and the goods are rinsed. A print of good depth of colour and good general fastness properties, in particular good fastness to boiling with sodium carbonate, is obtained. Similar results are obtained with the recipes indicated in the Examples which follow.

Example 2 a) Printing paste: Dyestuff according to British Patent Specification 1,188.606. Example 6 100 g Toluene 840 g Ethylcellulose N 22 60 g 1000 g The constituents are dispersed in a bead mill for 30 minutes.

b) Wetting liquor: Emulsion as in lb) 960 g + Na methylate 40 g 1000 g The transfer and fixing conditions are as under 1).

Example 3 a) Printing paste: Dyestuff according to British Patent Specification 1,188,606. Example 15 50 g Urea 50 g Na alginate/half-emulsion 900 g 1000 g b) Wetting liquor: Emulsion as in lb) 910 g NaCI 50 g Calcined sodium carbonate 10 g Ethylene carbonate 30 g 1000 g The transfer and fixing conditions are as under 1).

Example 4 a) Printing paste: Dyestuff according to British Patent Specification 1,188,606, Example 15 60 g Ethanol 890 g Ethylcellulose N 22 50 g The constituents are ground in a ball mill.

b) Wetting liquor Solution of a poly-ammonium acrylate 970 g Na bicarbonate 30 g The transfer is carried out in a calender under the customary conditions at 105"C for 40 seconds under 3 bars.

WHAT WE CLAIM IS: 1. A process for carrying out wet transfer printing with the aid of an anionic reactive dyestuff characterised in that a reactive dyestuff containing a monofluoro-triazine reactive group, and having a reaction constant of at least 1 x 10-2 minute -' at pH 10 and 60"C is used.

2. A process according to claim 1 wherein the substrate printed by the process is a cellulose material or a natural or synthetic polyamide.

3. A process according to claim 2 wherein the substrate is a cellulose material, the reaction rate between the OH groups of the cellulose being increased by increasing the alkalinity of the wetting liquor.

4. A process according to any one of claims 1 to 3 wherein the wetting liquor or printing paste for printing a temporary support contains an electrolyte.

5. A process according to claim 4 wherein the electrolyte is sodium chloride or sodium sulphate decahydrate.

6. A process for wet transfer printing according to claim 1, substantially as hereinbefore described with reference to any of the Examples.

7. A material when printed by a process according to any one of claims 1 to 6.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   Example 4 a) Printing paste: Dyestuff according to British Patent Specification 1,188,606, Example 15 60 g Ethanol 890 g Ethylcellulose N 22 50 g The constituents are ground in a ball mill.

   b) Wetting liquor Solution of a poly-ammonium acrylate 970 g Na bicarbonate 30 g The transfer is carried out in a calender under the customary conditions at 105"C for 40 seconds under 3 bars.

   WHAT WE CLAIM IS: 1. A process for carrying out wet transfer printing with the aid of an anionic reactive dyestuff characterised in that a reactive dyestuff containing a monofluoro-triazine reactive group, and having a reaction constant of at least 1 x 10-2 minute -' at pH 10 and 60"C is used.
2. 2. A process according to claim 1 wherein the substrate printed by the process is a cellulose material or a natural or synthetic polyamide.
3. 3. A process according to claim 2 wherein the substrate is a cellulose material, the reaction rate between the OH groups of the cellulose being increased by increasing the alkalinity of the wetting liquor.
4. 4. A process according to any one of claims 1 to 3 wherein the wetting liquor or printing paste for printing a temporary support contains an electrolyte.
5. 5. A process according to claim 4 wherein the electrolyte is sodium chloride or sodium sulphate decahydrate.
6. 6. A process for wet transfer printing according to claim 1, substantially as hereinbefore described with reference to any of the Examples.
7. 7. A material when printed by a process according to any one of claims 1 to 6.