Oligomer & the importance of Oligomer remover------- Oligomer is a smaller chain length of polyester made up of two or more molecules of basic ethylene terephthlate i.e. dimer or trimer, produced as a side reaction during the manufacture of polyester. The Oligoester because of its smaller chain length is in the form of a fine powder which is entrapped is basic polymer and migrates to the surface during high temperature polyester dyeing. Higher the depth more is the displacement of Oligomer to the fibre surface. Typically polyester fibres contain between 1.5-3.5% by mass of low molecular esters, the principal oligomer being cyclic tris (ethylene terephthalate) with smaller quantities of dimer, pentamer & other compounds. Approximately 0.1 % to 1.0 % of Oligomer is produced as a side reaction in the manufacture of basic polyester. Oligomer & the importance of Oligomer remover, problems caused on its deposit, Removing Art, Solutions----

2. Oligomer is a smaller chain length of
polyester made up of two or more
molecules of basic ethylene
terephthlate i.e. dimer or trimer,
produced as a side reaction during
the manufacture of polyester. The
Oligoester because of its smaller
chain length is in the form of a fine
powder which is entrapped is basic
polymer and migrates to the surface
during high temperature polyester
dyeing.
cyclic tris (ethylene terephthalate)

3. Higher the depth more is the
displacement of Oligomer to the fibre
surface. Typically polyester fibres
contain between 1.5-3.5% by mass of
low molecular esters, the principal
oligomer being cyclic tris (ethylene
terephthalate) with smaller quantities of
dimer, pentamer & other compounds.
Approximately 0.1 % to 1.0 % of
Oligomer is produced as a side reaction
in the manufacture of basic polyester.cyclic tris (ethylene terephthalate)

4.  Spinning characteristics impaired.
 Filtration effect (inside – out variation) due to build up of
Oligomers in package.
 Reduced liquor flow through package of yarn because
spindle perforations are choked & improper pump
pressure due to deposits on pump.
 Variation in rate of rise of temperature due to deposits on
heating elements
 Dusting during coning & white particle deposits cause
dulling of the yarn/ fabric especially in dark shades i.e.
black & navy etc.
 Higher energy costs
 Presence can cause nucleation & growth of dye crystals
or agglomeration of dye particles & hence dye spots,
Duller shades, unlevelness & poor fastness.
 Need for more frequent cleaning of dyeing & winding
machines, hence increased down time & lower efficiency.

5. Those skilled in the art have therefore tried to remove
oligomers from polyester by means of various after-treatment
methods.
For example, it is known that oligomers may partly be
eliminated by rinsing the polyester with hot water or by
subjecting the polyester to an alkaline reductive after-
treatment in the presence of a tenside, for example a fatty
acid polyglycol ester, at elevated temperatures.
However, cyclic oligomers may be difficult to remove and
resistant to such an alkaline post treatment. Therefore, to be
effective, alkaline treatment must be severe, which results in
a significant loss of polyester fiber material.

6. Organic solvents have also been used to try to remove
oligomers from polyester but it is difficult to find one
that is compatible with and non-injurious to the textile
material.
Chlorinated hydrocarbons, fluorinated hydrocarbons and
hydrocarbons themselves have also been used in the art
to remove oligomer deposits.
All of the before-mentioned treatments used in the art
pose production problems along with time and cost
issues.
Accordingly, there is a need in the art for removing
oligomer deposits that results in minimal interruptions in
production and poses little threat to the quality of the
polyester or polyester textile product.

7. Cyclic tris (ethylene terephthalate) is insoluble in water.
Solubility is increased in presence of carriers like Dylev-EC,
Dylev-CB , Dylev-DIF promotes migration of the trimer to the
surface of fibre. But a dispersing agent like Dytec-DAN should
be present to prevent crystallization & deposition of the
oligomers.The longer the dyeing time the more oligomers will
be released. Dark shades may produce more oligomer than
paler shades because the dyeing time is longer.
When oligomers are released from polyester fibre, after some
time at 130ºC, there will not be an efficient dispersing agent in
the bath to prevent crystillization of the oligomers, and to
prevent small particles of oligomers coming together to form
agglomerates, & depositing on the yarn & the machine.
Altrasperse-OLG liquid will maintain the oligomers in fine
dispersion form & prevent redepositing of the trimers on the
fabric so that when the machine is drained more oligomer goes
down the drain.

8. Receipe during dyeing:
In the case of dark shades and/ or long dyeing times, the following
formulation is recommended :
0.5 – 2 g/l Altrasperse-OLG liquid
0.5-1.0g/l Dylev DIF / Dylev-CB
0.5 g/l Dytec-DAN
Receipe during alkaline weight reduction of polyester:
During alkaline weight reduction of polyester terephthalic acid is
generated & to keep it in dispersion form Altranol-OR is very
effective. Altranol-OR act as a effective micronizer & disperser of
terephthalic acid.
Altranol-OR 1-2 g/l 75-80ºC for 20-30 mins
100-130ºC Warm rinsing
Weight reduction
Neutralization
Altranol-OR(75-80ºC)

9. The dyeing machine to be cleaned is filled with
water and the following is added:
3-5 g/l Altranol-ORM
4-6 ml/l Caustic soda solution 50%
1-2g/l Sodium hydrosulphite
Then heated upto 135ºC and treated for 20-40
mins. If possible, drain immediately and rinse.
Otherwise, cool to approx. 90ºC, drain and
rinse. On dyeing machines such as jets and
overflows the additional use of a CO back cloth
has proved of advantage to increase the
cleaning effect further.
Pot After Dyeing
Pot After cleaning with
Altranol-ORM

10. In order to assess dispersion performance of oligomer
remover , the degree of dispersion is to be compared with and
without Altranol-OR/Altrasperse OLG in the black filter paper
(A filter paper is soaked in the black direct dyes for 24 hrs &
dried)
Extracting the oligomer in Dioxane:
Dioxane 100% 100-250 cc
Polyester cloth 5-20 gm
Treatment 130ºC x 60 min
Oligomer dissolves in dioxane
Take 5-20 gms of undyed polyester fabric & to it add 20
times the weight of fabric Dioxane & treat the bath at
130ºC for 60 mins, cool & collect the solution. This is
the solution of oligomer in Dioxane.

11. Oligomer dispersion test (Contd)
Test on dispersion in acidic solution
Take 10 cc of the above collected oligomer solution & to it add
200cc of water & keep it aside for 15-20 mins, white precipitates of
oligomer will start settling.
Bath-1(Blank)
Oligomer solution 10 cc/200 cc
Acetic acid pH=5
Bath-2(With oligomer remover)
Oligomer solution 10 cc/200 cc
Altrasperse-OLG/Altranol-OR 1-2 g/l
Acetic acid pH=5
The above bath with & without oligomer remover is kept for
60 minutes & the filter through the black dyed filter paper &
observed for the residual oligomer or white precipitates
against blank.

12. 2. Test on dispersion during weight reduction
Test Purpose: Dispersion of terephthalic acid generated by weight
reduction
Specimen: Liquor after weight reduction
Test items: Vacuum filter(Using black coloured filter paper
Test condition
Products Blank 1 Test No-1 Blank-2 Test No-2
Liquor
after
weight
reduction
20%
solution
20%
solution
5%
solution
5%
solution
Altranol-
OR
--- 2 g/l --- 2 g/l
Acetic
acid
pH
4.5-5.5 4.5 - 5.5 4.5 – 5.5 4.5 – 5.5
Blank
20% liquid of caustic
treatment
20% liquid of caustic
treatment
Altranol-OR(2 g/l)

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