Transfer Printing
[6]
[10]
Transfer printing employs dyes that sublime; use of this method
may transfer the dye emissions from a water medium to the atmosphere
surrounding the machine. Use of this method could have a greater
impact on worker exposure than wet dyeing methods.
In transfer printing, paper is first printed with volatile disperse
dyes. The printed paper is heated together with a textile material
in a thermopress at up to 200 degC for thirty seconds. Under these
conditions, the dyestuff is transferred from the paper to the textile
material by sublimation. The transferred dyestuff has a good washing
fastness. [10]
- Transfer printing involves only the dyestuff and no other chemical is
deposited on the textile material, so no after-washing is required
and no effluent is generated [10]
;
- For conventional printing, 250 Kg of water per Kg of textile
is required. In transfer printing only 2 Kg is needed
[10]
;
- Low rates of production as well as the limitation to volatile
dyes (and to fibres which have affinity with these dyes)
[10]
;
- Dyestuff consumption is considerably lower than with direct printing
on textiles. A dye yield of 80% can be realized with printed paper
transfer, and penetration can be better controlled. With no need
for after treatment, hardly any water is consumed leading to less
effluent generation [10]
;
- Considerably less energy is consumed during drying. Approximately
one-half ounce of water per square yard is used in transfer printing
compared with between seven to 32 ounces of water per square
yard used in direct printing. No after treatment such as steaming,
washing or drying is required [10]
;
- Transfer printing is cheaper [10]
;
- It demand less production space, fewer skilled staff and creates
less pollution [10]
;
- In its present form, transfer printing is only suitable for some
synthetic fibres and cannot yet be used for natural fibres. It
has been particularly successful with polyester. Some transfer
printing has been done on acrylic, nylon 66 and triacetate. Some
wool has been successfully printed by means of the so-called Fastran
process after a pre-treatment [10]
;
- Due to the nature of the present transfer process as well as
the low quantity of dyestuff delivered to the paper, the penetration
of the dye into the fibre is also limited. This is a particular
problem with knit goods as the base colour of the substrate becomes
visible when the cloth is stretched
[10]
.