SGIA Journal Garment Edition Spring 2016 - 37

As the market was asking for printed
polyester, they had to deliver, but they
couldn't deliver in reality because the inks
for doing direct-disperse digital print were
not reliable, creating more problems than
expected. Therefore, numerous textile
printers added smaller-sized equipment to
their production portfolio and started to
print on paper, and then do sublimation.
Although this is easy and cheap, it is
quality-wise not always what is expected
by their customers.
On the supply side, things have taken
a turn for the better. In the early days of
printing direct disperse on high-speed
machines (e.g. Kyocera head machines) it
was obvious that there was a general problem:
* Too much 'glycols' in the inks
* Not the most stable dispersions
* Open time at nozzle
The glycols give an array of issues in
the printing process. They help elevate the
viscosity of the inks, which is needed to
get a certain print performance from the
inkjet printhead.
But the elevated viscosity also has the
negative effect that less dyestuff can be
dissolved or dispersed in the inks itself.
This causes a lower color yield.
Another negative effect of the glycols
is that the drying characteristics of
the inks become different as well. The
boiling point is higher than 130°C, which
causes a normal dryer that runs at a fairly
standard 130° to insufficiently dry the
fabric. This can cause staining, stamping
or marking of the design on other parts
of the fabric when it's rolled.
The fact that not all inks in the field
are very stable dispersions can cause
havoc. Most inks tend to dry slowly,
but when they do dry, they dry almost
like a pigment with binder. When this
happens on the nozzle plate, the heads
can easily become clogged. It is of utmost
importance that this type of drying of
inks in the print head should be avoided
at all costs.
So making a reliable working ink
for direct printing on to polyester is
therefore an extremely challenging task.
Looking back, the market history of
direct-disperse inks is one of difficulty.
The initial ranges of direct-disperse
inks had a dramatic effect on the lifetime
of the Kyocera heads. This was improved
by most vendors, a nd t he second
generation of direct-disperse inks had
a much improved run capabilities and
lifetime score, but all of them scored lower
on available color gamut.

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Current Status

N o w, a f t e r t w o m o r e y e a r s o f
development, SPGPrints has been able
to come up with the next generation of
direct-disperse inks that combines good
run capabilities and lifetime scores with
very bright and vivid colors, and easy
drying on the fabric. This will enable
customers to maximize their results in
disperse printing.
Due to the fact that the inks are based
on high-energy dyes, they are usable in
a direct printing method. Fixation of the
dyestuffs can be done in the traditional
ways, so either by high-temperature
steaming, high-pressure steaming (not
common nowadays), hot air or hot-roller
fixation. This therefore also opens up
possibilities for people who have been
active in the 'dye-sub' field.
Pretreatment of the fabric is necessary
to maximize the color gamut, but is
limited to simply padding a certain
recipe, containing mainly thickeners, on
to the fabric. For flags and banners there
may be no need for pretreatment.
Washing is necessary, as with all
direct-print methods. A traditional
reductive clearing will make sure that
fastnesses are maximized and meet the
requirements of end-customers.
The latest Nebula-type disperse-direct
ink (for Kyocera) is available in Black,
Cyan, Magenta, Yellow, Orange, Red,
Blue and Violet. The ink is also available
as Flare-type ink, for Epson DX4/DX5
heads. The eight colors together ensure
the maximum color space.
By having that large color gamut available
in a direct-print method, manufacturers can
achieve the qualities that are needed by their
customers, the brands.
Through print, one of the biggest
problems of the dye-sublimation method,
is not an issue any more on thinner fabrics.
If needed, this is even possible on thicker
fabrics, by using SPGPrints' patented
penetration fluid, something that is not
available in dye-sublimation printing.
The fastnesses of the direct method
commonly outperform the fastnesses
of dye sublimation. Drying of the ink
on the heads is prevented, due to the
chemical composition of the inks. Drying
of the ink on the fabric is helped by using
slightly longer driers, which are specifically
designed for drying disperse-dye on fabric,
like the newly developed dryer for the Pike
single-pass printing system.
All in all, there are no reasons any
longer why the volume of digital printing of
polyester fashion fabrics using true directdisperse inks should not grow dramatically.

Rene Wolferink, Application Specialist
at SPGPrints, has been in the digital textile
industry since the mid-199os, initially at in
the technical marketing group of Stork Digital
Imaging BV, where he helped customers to
integrate their conventional processes into the
newly arrived digital process.
From 2006 to 2010 he has was in charge
of the operations of Digital Print Asia, in
Thailand at that time one of the bigger digitalprint production facilities, with a focus on
sportswear, swimwear and intimate apparel.
He currently he works at SPGPrints as an
application specialist in digital textiles, and
therefore takes the lead in supporting customers
at their own sites in the implementation
of solutions encompassing machinery, inks,
software and more. He is also a member of
the development teams that makes sure future
SPGPrints products meet the demands of the
current and future customers.

SGIA Journal ■ Spring 2016 | 35

SGIA Journal Garment Edition Spring 2016

Table of Contents for the Digital Edition of SGIA Journal Garment Edition Spring 2016