Tests for practical application at five printing factories
in Indonesia
Using dye in same way as in direct printing
Naoharu Oyabu, printing consultant
Printing consultant
Mr. Naoharu Oyabu. |
Because of the high cost of discharge printing, testing of low-cost resist printing
for polyester is now underway in Indonesia. The details are introduced below
by N. Oyabu.
The discharge printing of polyester uses disperse dyes selected for use in
discharge printing and requires processed tin chloride, tin chloride or alkali
agents.
In Asia, ICI chose Indonesia during the 1980s in its efforts to popularize
alkaline discharge printing using disperse dyes.
In Japan, only around 3% of factories use the alkaline discharge method,
discharge printing using processed tin chloride being far more common. The popularity
of the use of processed tin chloride is not only due to its lower cost relative
to alkali methods, but also because it has a better stability. It now appears
that this method has also been introduced in South Korea.
In Indonesia, however, direct printing is really the only method used, discharge
printing being discouraged by the high basic costs.
However, due to technological differentiation, there has been an increase
in the number of factories hoping to produce printing results similar to those
of discharge printing at a low cost.
Different types of samples (polyester) from resist/discharge
printing tests. |
In the discharge printing of polyester, there are restrictions in the types of
disperse dyes which can be used, and careful selection is also necessary in choosing
illumination dyes.
The goal of achieving discharge printing at the same cost as direct printing
leads to the adoption of resist printing technology.
Currently a common goal in Indonesia is that of achieving resist/discharge
printing at low cost with normal disperse dyes without using dischargeable dyes
for the ground color.
To achieve this, I have been promoting tests of a new resist printing processing
method at five printing factories in Indonesia.
My goal is to produce a resist printing method which produces results similar
to those of discharge printing using processed tin chloride. The method I am
promoting in tests in Indonesia uses disperse dyes for the ground color in the
same way as in direct printing.
The stock paste uses Resist GNP.
The following explanation corresponds to the current period (April 2002)
of testing in Indonesian textile printing factories. While the tests are not
being conducted totally in accordance with my recommendations, by looking at
the strike-off samples to date, one can see clearly that the chances of success
are good.
The stock paste used is Resist GNP, half of the ingredients of which were
produced in Japan, so there is a high level of solid content in all the resulting
blends and it is effective in preventing the penetration of dye during the resist
printing process.
Because the viscosity of the color paste using Resist GNP is 9000-10000cps,
there is the advantage that it can be used in rotary screen printing and in auto-flat
printing.
I have called this new printing method with Resist GNP the "Newly Developed
Resist Printing for Polyester."
This new resist printing method signals an improvement in resist printing
because it has a very low cost and constitutes a way of printing polyester that
does not involve the use of processed tin chloride or alkalis.
In this method, the dye can be selected from a wide range of non-dischargeable
disperse dyes, and because auxiliaries are unnecessary, there is no danger of
damaging the steamer. Furthermore, the chemical content of the wastewater is
less threatening to the environment.
The following is a description of resist printing according to the "Newly
Developed Resist Printing for Polyester."
Fig 1
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| (Click to enlarge) |
As shown in Fig. 1, printing machines can be used in three different ways.
1) and 2) show resist printing with an auto-flat screen printer, while 3)
shows resist printing with a rotary screen printer.
In resist/discharge printing with an auto-flat screen printer, the printing
of joints can be done very well, and according to current test results, method
2) is the most effective.
The content of the stock paste for the "Newly Developed Resist Printing
for Polyester" is as follows:
Stock Paste
Color Resist Paste
There is a wide range of illumination dyes that can be used, but those currently
involved in testing in printing factories in Indonesia include Poly White NT-1,
Polyron Red F3BS, Polyron Blue FBL, Polyron Yellow S6GSL, and Polyron Turquoise
Blue BGE.
The disperse dyes used for the ground color in the direct printing of the
polyester includ Black DSE, Brown OCS, Navy Blue SGL, Olive OCS, Rubine S2GFL,
Scarlet SBWFL, Blue 2E2R, Red GS, Turquoise Blue BGE and Yellow SE2FL. All are
dyes for direct printing.
Ingredients of Ground Blotch Paste
Polytex TM is a tamarind-based paste.
In addition, with experience gained through the "Newly Developed Resist
Printing for Polyester", the first test results for full-resist and partial-resist
printing have become available, but I will outline those results on another occasion.
Full-resist printing (resist printing of the whole surface)
| - |
The design covers the entire surface of the material, and the result is the
same as that for common discharge printing. |
Partial-resist printing (resist printing of designated sections)
| - |
The resist printing is in the design eg. the resist printing of parts of
a flower design, or of the fine lines in a striped pattern |
This method constitutes the widest application of resist printing technology.
Very little paste is used where color is applied, and it is an economical way
of producing enhanced results for a wide range of designs.
Table 1
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