AUXILIARY FOR THE REMOVAL OF RESIDUAL PEROXIDE

AVCOSAN HPK is an additive for eliminating residues of Hydrogen-Peroxide at the end of peroxide bleaching processes.
AVCOSAN HPK is a chemical auxiliary which is shortening the peroxide bleaching process of cotton and poly-cotton while saving water and energy.

SPECIFICATION:

Appearance	White,free flowing crystalline powder.
Chemical nature	Sulphur containing organic compound with mild reducing properties.
Compatibility	Is not compatible with oxidizing materials (Peroxide, Chlorine)
Ionic nature	Nonionic.
pH of 5% solution	App. 7
Solubility (20°C)	Soluble in water up to 100 g/l.
Stability	Stable to chemicals used in reactive dyeing. Stable to hard water.
Storage	Store in dry place in original packages. Stability to prolong storage is unlimited if properly stored.

PROPERTIES & USES:

In conventional dyeing method with reactive dyestuff fabric is pre-bleached with
hydrogen-peroxide and rinsed twice. Residues of peroxide can interfere in the dyeing
process by oxidizing the reactive dye. The results are unlevel and stained fabrics.
To ensure complete removal of residue of peroxide, hydrosulfite is added to the
rinsing bath. This procedure brings up a new problem of residue of hydrosulfite which
can influence the dyeing process. AVCOSAN HPK is a non-toxic and non dangerous
product, replacing hydrosulfite for removal of peroxide residues in high liquor ratio
bleaching processes in jets, winches and paddle machines.

AVCOSAN HPK eliminates peroxide residues in bleached fabric before dyeing, in a short
procedure with no risks to the dyeing operation.

Use of AVCOSAN HPK is shortening the bleaching process while saving energy and water,
and ensures more level dyeing, even when dyeing heavy tight fabrics in low liquor
ratio dyeing machines.
Over-dosing does not affect the dyeing process.

APPLICATION:

At the end of the bleaching procedure add to the bleaching bath 0.5 – 2 g/l AVCOSAN HPK (depending on the amount of peroxide residue) and treat for 10-15 minutes.
Drain bleaching bath.
Rinse with hot water at 50°C and adjust pH to 7 with acetic acid.
Refill dyeing machine with fresh water.
Start normal dyeing procedure.

REMARKS:

The quantity of AVCOSAN HPK is adjusted to the quantity of peroxide left in bleaching bath, which should be checked by using peroxide indicator.
In some cases it has been found that it is possible to shorten above process and save a lot of time and water, which means a bigger cost reduction in dyeing process:
- When dyeing hot reactive dyestuffs it is possible to continue from stage (1) to stage (5) without rinsing using the hot water of the bleaching bath as the dyeing liquor.
- When dyeing cold reactive dyestuffs it is possible to continue from stage (2) to stage (4) without rinsing but using fresh water for the dyeing liquor
In the two cases adjusting pH to 7 with acetic acid is a must. These two short procedures should be checked thoroughly before applying it in a bigger scale at the dyeing house.