LOW PICK UP FINISHING Green Textile Operation: How Can We Make It Profitable?

Public
EMRAH ESDER
BU Textile Chemicals
CHEMICALS
07.11.2010

LOW PICK UP FINISHING
Green Textile Operation: How Can We Make It Profitable?

Carbon Footprint

A carbon footprint is a measure of the impact our activities have on the
environment, and in particular climate change. It relates to the amount of greenhouse
gases produced in our day-to-day lives through burning fossil fuels for electricity,
heating and transportation etc.
The carbon footprint is a measurement of all greenhouse gases we individually
produce and has units of tones (or kg) of carbon dioxide equivalent
A carbon footprint is made up of the sum of two parts, the primary footprint (shown
by the green slices of the pie chart) and the secondary footprint (shown as the yellow
slices).

Public: LOW PICK UP FINISHING
EMRAH ESDER, BU Textile Chemicals, CHEMICALS (Copyright Clariant. All rights reserved.) 07.11.2010 Slide 2

Carbon Footprint

1. The primary footprint is a measure of our direct emissions of CO2 from the
burning of fossil fuels including domestic energy consumption and transportation
(e.g. car and plane). We have direct control of these.

2. The secondary footprint is a measure of the indirect CO2 emissions from the
whole lifecycle of products we use - those associated with their manufacture and
eventual breakdown. To put it very simply – the more we buy the more emissions will
be caused on our behalf.


Carbon Footprint – Textile Impact

The textile industry is one of the biggest GHG emitters on Earth, owing to its huge
size and scope. Many processes and products that go into the making of fibers,
textiles and apparel products consume significant quantities of fossil fuel. Apparel
and textiles account for approximately 10 percent of the total carbon impact. The
estimated consumption for an annual global production of 60 billion kilograms of
fabrics boggles the mind: 1 trillion kilowatt hours of electricity and up to 9 trillion liters
of water.
The direct carbon footprint contribution of manufacturing plants from yarn to
customer including spinning, knitting, dyeing, finishing, cutting and sewing, plus
transportation to the distribution center could reach up to 12.5 kg of CO 2 per kg of
fabric.
The carbon emissions of T-shirt manufacturing in CO 2 equivalents could be more
than 12 times the product weight. Considering that the carbon footprint of steel is
about 2 kg of CO 2 equivalents per kg of steel, the pressure coming down from the
supply chain to the full industry is understandable


Carbon Footprint: Ways of reduction in
Textile
Although there are many points where Textile has an impact on carbon footprint,
Energy saving and emission reduction on textile are the main key topics to be
considered in order to reduce the impact today.
There are many ways of saving energy & reduce emission in textile industry by using;
– Environment friendly chemicals
– Chemicals which require low temperature curing.
– Applications which save energy especially on drying and fixing stage.
– Applications which require less water consumptions.
– Products / Applications which require less waste water treatment.
– Combination of all.
We can start saving and reduce emission by lowering our pick-up !


Focus – Low Pick Up Finishing

There are 6 million tones/a of Textile Chemical usage in the world.
40% of Textile Chemicals used for finishing segment.


Introduction:
Impact - Low pick Up Finishing
During the past decade, much emphasis has been given to reduce energy required in
desizing, bleaching, dyeing and finishing of the fabrics.

The most effective way to reduce the energy consumed in finishing would be to
reduce the amount of water which must be evaporated. This is only possible by
reducing the wet pick up.

Reduction of wet pick up is highly desirable because:
–It saves energy in drying and fixing process
–It reduces migration in dyeing and finishing.
–It has positive contribution for environment by lowering carbon footprints.


Definition – Low pick-up finishing

Typically, pad applications of chemical finishes yield wet pickups in the 70–100 %
range. These high pickups necessarily require the removal of large amounts of water
during drying.
Low pick-up finishing describes wet pick-up levels between 5%-40%. These values
are very much depends on CAV (Critical Application Value) which is related to fiber
type, fabric construction and absorbency.
A finish application below the CAV may result in a non-uniform speckled treatment,
while an application above the CAV could lead to finish migration. Cellulosic fibers,
because of their inherent hydrophilicity, have CAVs in the range of 35–40 % wet
pickup. Hydrophobic fibers like polyester can have CAVs of less than 5 %, allowing
much lower wet pickups than hydrophilic fibers.
In order to minimize finish migration during drying and reduce the energy costs
associated with drying large amounts of water, various techniques have been
developed to reduce the amount of water used in finish applications.


Definition – Lower limits of pick ups &
CAV values
Pick Up limits of the conventional process CAV values of the fibers

CAV


Definition – Low pick-up finishing

An additional benefit is that some applications will allow precise placement of
chemicals, leading to the possibility of fabrics with different finishes on their face and
back.
Another advantage is the recovery and reuse of the finish liquor removed by some of
these techniques. To reduce the danger of uneven finish distribution on the fabric,
caused by low wet pickup, a thorough preparation is necessary by any method that
provides a very good and uniform absorbency.
There are two main types of low wet pickup applicators. The first is the saturation–
removal (Expression) type where the fabric is completely saturated with the finis
liquid and then the excess liquid is removed mechanically or with a vacuum before
drying.
With the Topical type, a precise amount of finish liquid is uniformly applied to the
fabric using transfer roll, spray or foam techniques.


Methods – Low Pick Up Finishing
There are two main possibilities to reduce the pick up;
–Expression Methods: To remove/reduce surplus liquor by squeezing or other means.
–Increase nip pressure
–Increase hardness of the rollers
–Decreased diameter of the pad roller.
–Use special composition of rollers
–Use Vacuum extractors.
–Topical Methods: To apply limited amount of liquid during the applications.
–Foam Applicators
–Kiss roll applicators
–Spray applications
–Other transfer methods.


Topical Methods – Kiss-Roll

The kiss roll, picks up the chemical finish and transfers it by direct contact to the
fabric.
The amount of finish picked up is dependent upon how well the finish wets the roll,
the absorbency of the fabric and to a lesser extent, the surface speed of the roll relative
to the fabric speed.


Topical Methods – Transfer Rolls

Another version of finish application with transfer rolls is the loop transfer system. A
loop of fabric is immersed in finish liquid and then squeezed with the fabric to be
treated between squeeze rollers.
The finish is transferred to the fabric at a much lower wet pickup than possible by
direct immersion. These roll transfer techniques are especially useful for the
backside application of finishes, for example hand builders and flame retardants, to
pile fabrics (without crushing the pile).


General Findings- Kiss-Roll & Transfer-
Roll applicators (Transfer Padding)
Although simple I concept, It needs strict control in order to achieve homogeneous
add on.
– Loop must be seamless and dimensionally stable on transfer padding.
– Build up risk of the running chemicals on the rollers especially if there is no
uniform absorbency properties on the fabric.
More suitable for
– Pre-coated fabrics with high absorption properties.
– Lightweight fabrics.
It is possible to run around 25-40% add on.
Functional finishes are possible.


Topical Methods – Triatex MA

One interesting modification of the kiss roll applicator is the Triatex MA machine
which uses on-line monitoring to control wet pickup. Figure below, shows a schematic
of the system.


General Findings– Triatex MA
applicators
Average pick up level : 25 %
Drying speeds can be increased as much as 50 % more compare to conventional
methods.
Surface migration of the chemicals has been virtually eliminated so possible
chemicals saving can up to 20%.
Different variety of finishing possible
– Resin Finishing
– Water & Oil repellents
– Antibacterial applications.
– Flame retardant applications.


Topical Methods – Spray Application

Chemical finishes can also be applied by spraying. By controlling the flow rate
through the spray bars, the amount of applied finish can be set to the desired add-on.
Care must be taken to avoid overlapping spray patterns that could lead to an
unacceptable uneven finish distribution. Special care is needed with aerosols from
fluorocarbon sprays (inhalation, followed by repellency of the inside of the lungs is a
deadly danger).


General Findings – Spray application

Very low add –on possible: 5%- 30%
Fabrics with different structure can be treated;
– Velour
– Flat Woven
– Corduroy
– Terry fabrics.
Different functional finishes possible
– Softeners
– Fluorocarbons
– Resins
– Anti-pilling treatments
– Fire retardants

Topical Methods – Foam Application

One important application method for chemical finishes is the use of foam to apply the
finish to the fabric. By replacing part of the water in the chemical formulation with air,
the amount of water added to the fabric can be significantly reduced.
In addition, surfactants are included in the formulation to be foamed.
Even if they are carefully selected, they may cause effect reduction of repellent
finishes.
The chemical formulation is mixed with air in a foam generator producing high
volumes of foam that can be applied to fabrics in a number of ways. The ratio of liquid
to air in a foam is referred to as the ‘blow ratio’, conveniently determined


Topical Methods – Foam Application

The stability of the foam is influenced by the components of the chemical system, the
viscosity of the foam and the method of foam preparation.
The half-life of a foam is the time in which 50 % of the liquid in a given foam volume
has been drained from the foam.
Foams for textile applications can have half-lives from a few seconds to several
hours.
Foam applicators can be used either for one side or for two sides
Single side Applicators


Topical Methods – Foam Applications

Double side Applicators


Topical Methods – Foam Applications

To make foam applications useful in Textile Applications, foams must be sufficiently
stable to insure uniform application of the chemical to the fabric.
Stability of the foam depends on many factors;
– Surface tension of the liquid
– Viscosity and elasticity of the film separating the bubbles
– Presence of electrolyte in the system.
– The size and uniformity of the bubbles in the foam.
– Foam temperature.


General Findings – Foam Finishing

In conventional finishing fabric passes in to a bath containing chemicals with typical
solids content ranging from 2-10 %. In this method, fiber content largely dictates the
wet pick up of the fabric.
General wet pick up at conventional systems;
– 100% Cotton: 70-100 %
– Blends of Polyester/Cotton: 60-80 %
– 100% Polyester: 40-50%
In conventional process, over 90% of applied finish is water which must be removed
in drying operation.
In a typical foam application process 5 to 25% solid content finish can be delivered to
the fabric.
With foam systems, up to 75% of the water in the finishing formulation is replaced by
air, thereby eliminating 75% of energy needed to remove water in the final
evaporation process.

General Findings– Foam Finishing

Ideal results on effects and uniformity can be achieved 30-35% add on cotton.
Especially on resin finishing made with foam at 26-28% add on can achieve same
properties compare to standard pad finishing with 65% wet-pick up.

Finishing of 50/50 Polyester/Cotton

Great Saving is possible



Resin Finishing on 50/50 Polyester/Cotton



Even with such highly absorbent fabric as cotton flannel by combination of increased
line speed and reduced temperatures energy saving can be achieved more than
70%.
Softener application on 100% cotton flannel


General Findings - Disadvantages

Main disadvantages:
– The finisher does not have the same flexibility in adjusting the finish formulation to
get required properties as he does in conventional finishing
– Set-up time is longer.
– Fabric dries out before it can be framed out to width.


Conclusion

For low pick-up systems, ideal add-on for the fabrics is 15%-35%
Most of the functional finishing such as resin, fluorocarbon, antibacterial on Cotton
and it’s blends:
– By experiment, the most comparable results with foam finishing(100% co &
Co/polyester blends) against to conventional padding process were taken around
28 %-30% add-on.
– With that add-on values, dusting issue has also been minimized.
– Below 25% it is difficult to maintain consistency but also problem of product
distribution on the fabric because of limited solubility.
Below 25% add-on values, there may be 5% fluctuation. In order to reduce that
value, we need to around 30 % or slightly above especially for functional finishes.


Conclusion

Despite the established many advantages of low pick up finishes and especially
foam finishing represents less than 20 % of all finishing.
Main Advantages:
– Get low pick up even down to 5% for various applications, quicker water drying
with energy saving of more than 50%.
– Chemicals can be saved in many circumstances in textile finishing treatments.
Stenter speed can be increased for drying or stenter, predrying can be eliminated.
– Shorten the length of equipment, plant and reduce the investment.
– Reduce environmental pollution and water waste.
– Can be carried on single or double-side of fabric (can be imposed on both sides
with different agents).
– Apply to different kinds of fabric, whatever its structure and composition
– Over all, it will help us to reduce carbon footprint !

Check out Clariant 4E’s Concept !


LOW PICK UP FINISHING Green Textile Operation: How Can We Make It Profitable?

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