Low temperature dyeing of polyester and polyester wool & other blends

Excerpt: Diffusion accelerator swell polyester fiber, increase inter polymer space and let the dye molecules to enter the polymer system easily.


The extreme crystalline nature of polyester fiber creates problems in obtaining dark shades by conventional dyeing methods even at high temperatures. Diffusion accelerators are found to assist the disperse dyes to enter the polyester polymer, enabling dark shades to be produced. Diffusion accelerator swell polyester fiber, increase inter polymer space and let the dye molecules to enter the polymer system easily.


Terradye-LTD Is a low foaming diffusion accelerant with leveling action for dyeing of polyester & its blends.

  • Eco friendly, Non toxic accelerator.
  • Accelerates dye diffusion especially in temperatures range 90⁰C to 100⁰C.
  • Improves dye migration.
  • Allows shorter dyeing cycles (hence lesser energy consumption and reduced occurance of oligomer deposits).
  • Gives better yields (hence reduced dye costs and cleaner machines.)
  • Promotes coverage of material induced barriness.
  • Accelerator for Polyester& its blends with cellulosics and wool.
  • Enables dyeing with deep shades.
  • Enables increase in the rate of dyeing.

Unlike in case of high temperature dyeing, dyeing with the Terradye – LTD does not cause any damages associated with high temperature (especially fabrics with metallic embroideries e.g. Silver, gold etc)

It enables larger dye molecules to diffuse rapidly into the fibre and is easily removable from substrate.

There are no adverse effects on light fastness and it is stable under standard dyeing conditions. It also improves rubbing fastness to great extent due to enhanced dye penetration.



  1. For light shade <0.5%
  2. For medium shade 0.5 – 1.5%
  3. For deep shade > 1.5%

Terradye – LTD - 0.5 – 1.0%

Acetic Acid: 1ml/lit

Aprojet – AIO - 2gm/lit

Salt (NH4)2SO4: 1 – 2gm/lit or Acetic Acid

pH : 4 – 5.5

M: L: 1: 10

Time: 45 – 60 mins

Temperature: 120oC 130oC (Temperature 120oC :- for PET / Wool blends)

Aprojet-AIO is a leveling, dispersing cum oligomer controlling agent

Recommended dosage

For dyeing at 95⁰c to 100⁰c for polyester with disperse dyes.

Application amount liquor ratio

1 – 2% (owf) of Terradye–LTD 10: 1 – 15: 1

Dyeing of polyester / wool blends

Following amounts of the product are recommended for dyeing polyester / wool blends at about 95⁰c to 100⁰c, at a liquor ratio 10:1 – 15: 1 depending on the depth.

Application amount of Terradye-LTD(higher dosages for higher depths)

(Depth %ge)shade 0.75% pale

1.0% medium

1.5% heavy

2.0% navy and black


  1. At first, a paste of dye and dispersing agent is prepared and then water at 60°C is added to it.
  2. Dye bath is set at 60°C temperature and all the chemicals are added to it. Rinse fabric for 15 min without raising the temperature.
  3. pH of bath is controlled by acetic acid at 4 – 5.5. Low temperature dyeing of PET / Wool blends also minimises staining of wool by disperse dyes.
  4. It is recommended to add an equal amount of water, to the amount of product required under manual stirring, or with a stirrer, at around 30⁰C. A stable emulsion is thus obtained, which can then be added, to the dyeliquor containing the standard additives.
  5. However, the application amount of Terradye – LTD depends on the quantity of the material being dyed, the depth of shade and the liquor ratio.

Advantages of dyeing at low temperature

  • In conventional dyeing method, the extremely crystalline polyester fibres cannot be dyed in deep shade. But by using diffusion accelerator we can get medium to dark shade in boiling temperature.
  • Materials can be dyed with simple equipments at atmospheric pressure and temperature below 100°C.
  • Some diffusion accelerates the reduction of wool staining while dyeing polyester – wool blends.
  • Rate of dyeing can be increased by using diffusion accelerators.
  • Can be dyed quickly by using diffusion accelerators.
  • Improves fastness properties of fabric except light fastness.

Author Details

N.A.Acharya, Vidyut Acharya, & Dr.S.S.Dhuri

Associated Chemicals

A-103, Gurudev Apts, Opp. Telephone Exchange, R.C. Marg, Chembur, Mumbai - 400 071.

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