GB1583947A - Textile transfer printing - Google Patents

Description

(54) IMPROVEMENTS IN AND RELATING TO TEXTILE TRANSFER PRINTING (71) We, COATES BROTHERS AND COM PANY LIMITED, of Cray Avenue, St. Mary Cray, 27080 Orpington, Kent, BR5 3PP, a British Company, 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 particu larly described in and buy the following statement : Large quantities of textiles are printed by transfer processes. These processes con sist in first printing the desired, usually coloured, pattern on a sheet or reel of a suitable substrate, usually paper, which may be stored until transfer to the textile is to be effected. The textile printer brings the printed surface of the transfer into contact with the textile and presses the two together finder conditions of dry or moist heat.In the dry process, dyestuffs are selected which transfer by sublimation. In the moist process dyestuffs which diffuse into the fabric under moist conditions are used. The latter process offers a wider choice of dyestuffs and it is with this process that we are concerned.

Paper is normally chosen as the transfer substrate because of its cheapness, but trans fer from a paper transfer sheet to a cellulosic textile such as cotton or viscose is incomplete.

We have now found that highly efficient dye transfer to cellulosic textiles occurs if the pattern is printed on a transfer sheet con sisting of paper coated with a layer of material impervious to the ink under transfer con ditions. Typical tsuch coatings are poly ethylene, poly vinylidene chloride and various polymers and copolymers of acrylic and methacrylic esters. There is however, a wide" choice of suitable coatings. The coatings must, however, satisfy the following conditions: The coatings must be film-forming, that is it must be possible to apply them to the paper in the form of a continuous, smooth, adherent film. This may be done by suitable known means, e.g. extrusion for polyethylene, emulsion coating for PVDC polyvinylidene chloridel solution or emulsion coating for acrylics.Polymer solutions may also be applied by a gravure printing process. In any event the coatings will generally be applied to the paper as thin layers, that is layers having a thickness of the order of a few microns, e.g. 1-5 microns.

The coating material should also be inert to the ink, that is the coating must not have a marked affinity for the dyes used in the ink. Thus, for example, one would not use an acrylic coating when the ink contains dyestuffs having a marked' affinity for acrylic fibres. Further the coating must not be lifted or appreciably softened by the solvents present in the ink under printing conditions.

Finally, the coating must be impervious to the ink under transfer conditions, that is the coating must act as a water barrier for times of up to about 5 minutes at temperatures of about 8Q100"C.

Accordingly, one embodiment of the invention provides a process for printing a cellulosic textile by bringing the printed surface of a transfer comprising a substrate printed with an ink for printing the textile into contact with the textile and pressing the transfer and textile together whilst heating the textile under moist conditions in which the substrate of the transfer comprises paper coated with a layer of a film-forming material inert to the ink and impervious to the ink under transfer conditions.

The choice of paper to be coated is not highly critical but for clean, sharp prints, it is preferred to use a paper with a hard, smo8th surface such as MG (machine glazed) or calendered stock.

The coating may be done as a first operation and the dried coated paper may be stored until required for printing (as will normally be the case with polyethylene and PVDC coated papers-these will usually be already coated when purchased by the printer).

Alternatively the coating may be applied "in-line" with the printing operation. Thus a reel of paper may be fed through a varnishing machine or a gravure printing press which will apply the coating, then through a suitable drier and finally directly into the printing press which will apply the coloured ink in the desired pattern.

Transfers printed on the coated papers are used in a wholly conventional transfer step and afford a means of greatly improving the efficiency of transfer to cellulosic substrates.

The inks used for printing are conventional textile transfer inks adapted to print cleanly on and adhere to the coated paper. Their precise nature will depend on the printing process to be employed and their formulation is within the knowledge of those skilled in the art.

A typical ink formulation for printing by the gravure process, suitable for subsequent transfer to cotton textiles, may comprise Direct Cotton Dye about 20 Polyamide Varnish about 45 O Anti-settling agent about 0 5%O Solvent about 34.50ft The polyamide varnish can be prepared by dissolving a suitable polyamide resin such as VERSAMID 933 (VERSAMID is a Registered Trade Mark) at about 40% concentrated in a suitable volatile solvent such as a mixture of toluene or aliphatic hydrocarbon of boiling range about 100-1200C with a minor proportion of iso-propanol and/or n-propanol. The anti-settling agent may typically be micronised hydrogenated castor oil.The dye, varnish and anti-settling agent would be ball-milled until thoroughly dispersed, and the solvent finally added to achieve printing viscosity. This solvent would normally be the same as that used in the preparation of the varnish. Typical direct cotton dyes are the SOLOPHENYL dyes of CIBA-GEIGY. (The word "Solophenyl" is a Registered Trade Mark.) As an alternative to the commercially available papers pre-coated with polyethylene or polyvinylidene chloride a suitable coated paper may be prepared as follows: China clay is dispersed in an acrylic copolymer emulsion (TEXACRYL 13-011 ex Scott Bader & Co. Ltd; this contains 40% of copolymer emulsified in water) with the addition of about 1% of silicone antifoaming agent to produce a coating composition containing 50 ,ZO total solids (polymer and clay) and a polymer:clay ratio of 2:1.

The inclusion of the clay is not essential but it gives a coating with a matt finish more receptive to ink than the polymer film alone.

This composition is applied to machine glazed paper using a conventional paper coating machine and the coated paper is dried in a current of warm air.

This paper was printed with an ink of the foregoing type by the gravure process.

A specimen of the uncoated paper was similarly printed.

Both transfers were applied to cotton fabric by means of a Hoffmann press.

Much dyestuff remained on the uncoated transfer. The coated transfer was almost completely free of ink. The effectiveness of the transfer was also clearly seen when the two samples of printed fabric were compared.

Similarly improved dye transfer was observed when commercially available polyethylene and polyvinylidene chloride coated papers were used.

WHAT WE CLAIM IS:- 1. A process for printing a cellulosic textile by bringing the printed surface of a transfer comprising a substrate printed with an ink for printing the textile into contact with the textile and pressing the transfer and textile together whilst heating the textile under moist conditions, in which the substrate of the transfer comprises paper coated with a layer of a film-forming material inert to the ink and impervious to the ink under transfer conditions.

2. A process as claimed in claim 1 substantially as hereinbefore described.

3. Textiles when printed by a process as claimed in any one of the preceding claims.

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

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. drier and finally directly into the printing press which will apply the coloured ink in the desired pattern. Transfers printed on the coated papers are used in a wholly conventional transfer step and afford a means of greatly improving the efficiency of transfer to cellulosic substrates. The inks used for printing are conventional textile transfer inks adapted to print cleanly on and adhere to the coated paper. Their precise nature will depend on the printing process to be employed and their formulation is within the knowledge of those skilled in the art. A typical ink formulation for printing by the gravure process, suitable for subsequent transfer to cotton textiles, may comprise Direct Cotton Dye about 20 Polyamide Varnish about 45 O Anti-settling agent about 0 5%O Solvent about 34.50ft The polyamide varnish can be prepared by dissolving a suitable polyamide resin such as VERSAMID 933 (VERSAMID is a Registered Trade Mark) at about 40% concentrated in a suitable volatile solvent such as a mixture of toluene or aliphatic hydrocarbon of boiling range about 100-1200C with a minor proportion of iso-propanol and/or n-propanol. The anti-settling agent may typically be micronised hydrogenated castor oil.The dye, varnish and anti-settling agent would be ball-milled until thoroughly dispersed, and the solvent finally added to achieve printing viscosity. This solvent would normally be the same as that used in the preparation of the varnish. Typical direct cotton dyes are the SOLOPHENYL dyes of CIBA-GEIGY. (The word "Solophenyl" is a Registered Trade Mark.) As an alternative to the commercially available papers pre-coated with polyethylene or polyvinylidene chloride a suitable coated paper may be prepared as follows: China clay is dispersed in an acrylic copolymer emulsion (TEXACRYL 13-011 ex Scott Bader & Co. Ltd; this contains 40% of copolymer emulsified in water) with the addition of about 1% of silicone antifoaming agent to produce a coating composition containing 50 ,ZO total solids (polymer and clay) and a polymer:clay ratio of 2:1. The inclusion of the clay is not essential but it gives a coating with a matt finish more receptive to ink than the polymer film alone. This composition is applied to machine glazed paper using a conventional paper coating machine and the coated paper is dried in a current of warm air. This paper was printed with an ink of the foregoing type by the gravure process. A specimen of the uncoated paper was similarly printed. Both transfers were applied to cotton fabric by means of a Hoffmann press. Much dyestuff remained on the uncoated transfer. The coated transfer was almost completely free of ink. The effectiveness of the transfer was also clearly seen when the two samples of printed fabric were compared. Similarly improved dye transfer was observed when commercially available polyethylene and polyvinylidene chloride coated papers were used. WHAT WE CLAIM IS:-

1. A process for printing a cellulosic textile by bringing the printed surface of a transfer comprising a substrate printed with an ink for printing the textile into contact with the textile and pressing the transfer and textile together whilst heating the textile under moist conditions, in which the substrate of the transfer comprises paper coated with a layer of a film-forming material inert to the ink and impervious to the ink under transfer conditions.

2. A process as claimed in claim 1 substantially as hereinbefore described.

3. Textiles when printed by a process as claimed in any one of the preceding claims.