| AVCOSAN LPD is a liquid product for eliminating residues of Hydrogen-Peroxide and Chlorine from bleaching baths. It is used as an auxiliary for one-bath/two stages bleaching and dyeing of cotton and poly-cotton with reactive dyestuffs, and in denim garments bleaching processes.
SPECIFICATION:
| Appearance |
Colourless, clear liquid. |
| Chemical nature |
Sulphur containing compound with mild reducing properties. |
| Compatibility |
Is not compatible with oxidizing materials (Peroxide, Chlorine etc.) and with acids. |
| Density (gr/cc) |
App. 1.25 |
| Ionic nature |
Anionic nature |
| pH of 5% solution |
App. – 7 |
| Solubility |
Soluble in warm water at any ratio. |
| Stability |
Stable to chemicals used in reactive dyeing. Stable to hard water. |
| Storage |
Stable for at least 12 months. |
PROPERTIES & USES:
In conventional exhaust dyeing method with reactive dyestuffs, the fabric is bleached
with hydrogen-peroxide and rinsed twice. 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 LPD is a chemical auxiliary, which is designed to eliminate peroxide residues
from the bleached fabrics before dyeing, in a short procedure with no risks to the
dyeing operation.
Use of AVCOSAN LPD shortens dyeing process, saves 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:
APPLICATION IN JET OR WINCH DYEING MACHINES:
Process A:
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At the end of the bleaching process add to the bleaching bath 1 – 2 cc/l AVCOSAN LPD (depending on the amount of peroxide residue) and treat for 15 minutes.
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Rinse with hot water at 50°C and adjust pH to 7 with acetic acid.
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Refill dyeing machine with fresh water.
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Start normal dyeing procedure.
Process B:
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At the end of the bleaching process drain liquor.
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Add fresh water at 80°C, apply 0.5 – 1 cc/l AVCOSAN LPD and treat for 15 minutes.
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Rinse with cold water and adjust pH to 7 with acetic acid.
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Start normal dyeing procedure.
REMARKS:
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Quantity of AVCOSAN LPD is adjusted to 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 process and to save time and water, which means a bigger cost reduction in dyeing process:
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When dyeing hot reactive dyestuffs it is possible to continue from stage – 1 (process A), or stage – 2 (process B) to stage – 5 without rinsing, using the hot water of the bleaching bath as the dyeing liquor.
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When dyeing cold reactive dyestuffs it is possible (when using process A) 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.
APPLICATION IN CHLORINE BLEACHING OF GARMENTS
In the end of the Chlorine bleaching process of DENIM garments, any residues of Chlorine may harm the strength of the garments. It is essential to destroy any residues of Chlorine by applying AVCOSAN LPD after the Chlorine bleaching treatment.
Recommended dosage is 2-4 cc/l AVCOSAN LPD.
Treat at 50-60°c for 5-10 minutes followed by hot and cold rinse.
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