Transfer printing

The fundamental concept of the transfer printing process is to print selected volatile non-ionic dyes on a paper and to transfer the dye to the fabric held in firm contact with the printed paper and heated at a temperature of about 180° to 220° Polyester and cellulose triacetate fabrics are ideally suitable for transfer printing.

The main advantages of the process are

(i) Complete dry system

(ii) Low cost of labor,

(iii) Better control of the process.

(iv) Better quality of print, and

(v) any effect of paper can be reproduced on the fabric.

However, there are limitations to this process and they are

(a) Applicable to hydrophobic fabrics,

(b) the Limited number of dyes for application.

(c) Special paper is required for printing and sometimes bigger width papers are not available,

(d) variation in depth of shades with papers from different sources.

Paper Printing

Printing of paper is carried out by several methods used in the graphic industry. The most popular method is gravure and almost 90 % of the paper is printed with a Rotogravure printing machine. The rotary screen printing machine is also used to print paper

Inks for Printing

Inks are made up of dyestuffs having high vapor pressure and low sublimation fastness. This dyestuff's arc is thoroughly ground and converted into a solid solution in a polymer i.e. ethyl cellulose. After printing, the paper is coated with resins on, a lacquer. This is essential for the paper to stick to the fabric for true contact and for avoiding relative movement of the paper concerning the fabric during transfer

Machines

The machines used for transfer printing are essentially hot plates in which the temperature is maintained in the desired range.

The machines are of two types,

batch-wise or continuous i.e. flatbed drum or calendar. The fabric is placed on a flatbed or drum. The printed paper is placed on the fabric with the printed surface of the paper in contact with the fabric and then heat pressed to get the transfer of the paper within 15 to 30 seconds at 180 to 220°C. Washing of the transfer printed fabric is not necessary.

Advantages of Transfer Printing :

The operation of transfer printing is varied and simple and does not require expensive machinery, only one small machine is all that is required. ( "here is no after-treatment of tho printed material-no (! As the operation is simple,

no skilled labor or a color Buydojanep Jo Buena 'Buwtos 'Buusom 'Buikup chemist is required: the cost of labor is low; The operation is quite clean ensuring freedom from (A! soiling of hands and clothes:

Faults do not occur in printing because the defects are the rejects are few. Aguenbosuos es!

Bunupd seeded jo arms out e pennies the machine requires considerably less: space for installation than that required for conventional printing machines.

In multi-color printing, the method gives precise registering and permits the production of intricate designs, lice lines, and gradation effects, including animal skin artifacts.

There is no need to store printed goods, It is possible to print knitted goods and garments as well as grey fabric (provided it is free from stains.)

Disadvantages of Transfer Printing:

The process is mainly applied to polyester material; the prints on other synthetic fibers like nylon or acrylic have poor vet fastness and those on polyester-cotton blends are skittery.

The process does not apply to natural fibers like cotton or silk as they are not thermoplastic

The color range l.e. the number of dyes used for printing is limited. ( The cost of printed paper is high and its width is limited. The process is not economical for short runs of the fabric and the design on the pre-printed release paper cannot be modified last-minute color changes are not possible.

Colorfastness to the light of the printed material is low as compared to the fastness obtainable by the conventional Sutuud jo pouts