Oligomer Remover- a presentation.

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Oligomer Removers
2011-2012
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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.
What is Oligomer the importance of Oligomer
remover
cyclic tris (ethylene terephthalate)
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What is Oligomer the importance of Oligomer
remover(contd)
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)
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Problems Caused by oligomer deposit

• 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.

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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.
 
Oligomer Removing Art
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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.
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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.
Solutions for Oligomer removing
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Receipe during dyeingIn the case of dark shades
and/ or long dyeing times, the following
formulation is recommended 0.5 2 g/l
Altrasperse-OLG liquid0.5-1.0g/l Dylev DIF /
Dylev-CB0.5 g/l Dytec-DANReceipe during
alkaline weight reduction of polyesterDuring
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)
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The dyeing machine to be cleaned is filled
with water and the following is added 3-5
g/l Altranol-ORM4-6 ml/l Caustic soda solution
501-2g/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.
Removal of oligomers from dyeing machines
Pot After Dyeing
Pot After cleaning with Altranol-ORM
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Oligomer dispersion test
In order to assess dispersion performance of
oligomer remover , the degree of dispersion is to
be compared with and without Altranol-OR/Altrasp
erse 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.
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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 ccAcetic acid pH5 Bath-2(With
oligomer remover)Oligomer solution 10 cc/200
ccAltrasperse-OLG/Altranol-OR 1-2 g/lAcetic
acid pH5 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.
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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
20 liquid of caustic treatment
20 liquid of caustic treatment
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
Altranol-OR(2 g/l)
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