Polyester getting tinted while dyeing Reactive Turquoise Blue combination of a poly/cot blended knit fabric. How to dye without tint?

Posted on January 30, 2010. Filed under: dyeing | Tags: , , |

Given below may be the best route for processing a knit poly-cot blend:

Pretreatment:

1. Wetting off:

Recipe:

Wetting agent (No foaming) = 0.5%

Treat @ 70°C for 10 minutes.

Drain.

2. Scouring & Bleaching:

a. Recipe:

i. Soda Ash = 0.5%

ii. Caustic Soda = 0.7%

iii. Non foaming detergent = 0.5%

iv. Peroxide Stabilizer = 0.5%

v. Hydrogen Peroxide(50%) = 1.5%

1. @ 85°C for 1 hour.

2. Drain and do cold wash

3. Neutralization:

a. Recipe:

i. Acetic Acid = 1 ml/liter

1. Treat @ cold for 10 minutes.

2. Wash cold 10 minutes

3. Check pH and let it be 6

4. Heat Setting:

a. Do heat-setting in a stenter @ 200°C for 30 seconds (split open) with 3% overfeed on pins at 15 meters/minute speed.

5. Mercerising:

a. Recipe:

i. Caustic lye = 50°TW

ii. Permenol N = 10 ml/liter (Mercerizing Wetting Agent)

Wash free from residual alkali

6. Polyester Dyeing: (Optional)

a. Recipe:

i. Lyogen PESI = 1.0 g/l (Dispersing & Leveling Agent)

ii. Acetic Acid = 1.0 g/l

1. Run @ 50°C for 10 minutes

iii. Add dissolved dyestuff @ 50°C and run 10 minutes

iv. Raise the temperature from 50 to 115°C @ 2°/minute – 30 minutes

v. Raise the temperature from 115 to 135°C @ 0.5°C/minute – 40 minutes

vi. Cool to 80°C and drain

7. Reduction Clearing (R.C.):

a. Recipe:

i. Cyclanon ECO = 2 grams/liter (Reduction Clearing Agent from BASF)

ii. Acetic Acid = 2 grams/liter

1. Treat at 80°C for 10 minutes

2. Wash cold

8. Reactive Dyeing:

a. Set pH to 6 by addition adequate quantity of Acetic acid ( may be up to 0.3 to 0.5 cc/liter)

b. Cotfix Turq Blue H2GP = 3.0%

c. Cotfix Yellow ME4GL = 1.0%

d. Glauber’s Salt = 80 grams/liter OR

e. Soda Ash = 20 grams/liter

i. Dye using Special Turquoise Blue Dyeing Method

a. Cotfix Turq Blue H2GP = 3.0%

b. Cotfix Yellow ME4GL = 1.0%

c. Glauber’s salt = 80 grams/liter

d. Soda Ash = 10 grams/liter

e. Caustic Soda Flakes = 2.75 grams/liter

Dye using the Special Turquoise Blue Preconditioning Method:

9. Neutralize:

Acetic Acid 2.5 grams/liter (instead of 1 g/l)

10. Soaping:

a. Method -1:

I – Soaping:

Recipe:

Lissopol D paste 2 grams/liter @ 80°C for 20 minutes.

II – Soaping:

Recipe:

Lissopol D paste 1 gram/liter @ 80°C for 20 minutes.

b. Method – 2:

I – Soaping:

Recipe:

Sandopon RSK Liq 2 grams/liter

Lyocol RDN 1 gram/liter (dispersing agent for Disperse dyes – used here for better soaping)

@ 80°C for 20 minutes.

II – Soaping:

Recipe:

Sandopon RSK Liq 1 gram/liter

Lyocol RDN 0.5 gram/liter

@ 80°C for 20 minutes.

c. Method- 3:

I – Soaping:

Recipe:

Cyclanon X-CW NEW = 2 gram/liter

Lyocol RDN = 1 gram/liter

@ 80°C for 20 minutes.

II – Soaping:

Recipe:

Cyclanon X-CW NEW = 1 gram/liter

Lyocol RDN = 0.5 gram/liter

@ 80°C for 20 minutes

Hot Wash

Cold Wash

11. Acetic Acid treatment:

Acetic Acid 0.5 cc/liter

12. If necessary use Formaldehyde free Cationic fixing treatment.

a. Sapamine OC = 1%

b. Cationic Fixing = 1%

i. @ Cold treat for 30 minutes.

ii. Wash cold

iii. Drain & unload the batch.

Note:

If a dose of 0.3 cc/liter of Acetic acid is incorporated in the soaping bath, the staining of reactive dyes on polyester during soaping may be completely avoided. Soaping bath pH should be 5 to 6.

A final wash after Soaping with 1 gram/liter of Acetic Acid or 0.5 gram/liter of Formic acid and maintaining a pH 5 to6 during drying would avoid tinting of reactive dyes by migration in to polyester.

Even after taking all precautions, if the polyester part still gets stained, treat the tinted fabric with:

Acetic Acid = 2grams/liter

Alcosperse AD = 2 grams/liter

Cibapon R liq = 2 grams/liter

At 80°C for 30 minutes; this would remove the stains from the polyester.

Summary:

1. In preparation no residual chemicals of the pretreatment should remain on the fabric. The RFD fabric should be checked for a pH of 6 at the end of pretreatment and before dyeing.

2. The pH should be 6 at the beginning of reactive dyeing.

3. After dyeing is over, neutralization with Acetic acid should be done and check the pH to 6.

4. Ensure sufficient hot wash to reduce the electrolyte (salt) concentration to a minimum of 1 g/l before soaping, otherwise imperfect soaping would be done.

5. During soaping maintain a pH of 6 to avoid staining of polyester.

6. The soaping temperature should be maintained strictly at 80°C. More than this would open the polyester fiber and create a tendency for unfixed reactive dye to enter into polyester fiber as stain.

7. The final pH should be 6 before drying and it may be controlled by using 0.5 cc/liter of Formic Acid.

Notes on Resin finishing:

Recipe:

Resin KVS = 45 g/liter

PV Acetate = 25 g/liter

PVA = 25 g/liter

PE = 20 g/liter

Acetic Acid = 1 cc/liter

Pad 2 dip 2 nip – pressure 35 kgs/sqcm. – speed 25 mtrs/minute and temperature – 170°C – No over feed.

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