Cold Pad Batch Dyeing Machine

Cold pad batch dyeing machine is the easiest process of woven fabric dyeing. In cold pad batch dyeing machine both dye & chemicals are added in the same bath. The ratio of dye & chemical is 2:1. If 1000 liter liquor is to be prepared then 100% will be dye & 50% will be chemical. After mercerizing batcher is feed into the inlet of CPB machine. Where the fabric is passed over some free roller & guider. Here there is a compensator to control fabric open width entry & controlling fabric speed.

Application of Pad Machine

• Flexible dyeing of short slots.
• Even coloration.
• Maximum dyestuff yield.
• Fast slot &color change.
• Minimum rest liquor.
• Reproducibility of shade.

Sketch Diagram of Cold Pad Batch Dyeing Machine

Process Description with Pad Machine

Chemical Tank: Both chemical & color is prepared in different tank according to required. For example we need 1000 liter liquor then we will prepare 100% dye solution & 50% chemical. Then both of them are mixed & agitated in storage tank from which it is feed in to padding bath.

A typical recipe for 128×56/16×10 twill:

10. Nova Yellow NP – 10.5 gm/lt
11. Nova Blue CR – 5.00 gm/lt

iii. Nova Red CD – 2.00 gm/lt

1. Soda Ash -15 gm/lt
2. Caustic -5 gm/lt
3. Albaflow pad (wetting)-2 gm/lt

Padding Unit: Here chemical comes from storage tank to maintain even range on padding tank. Here three bowl padding is occurred. Padding pressure is predetermined according to pick up required & fabric speed.

Batching: After padding fabric is directly rolled in to batcher& packed with poly bag. Then it goes for rotation of 8 – 12 hours for color fixing.

Washing: Finally the fabric washing, soaping, neutralizing & drying is occurred.

Testing required during Cold pad batch operation

• Pick up testing,
• Shade matching.

Pick up testing:Before going to Pad steam pick up of the fabric should be calculated & based on this result liquor is prepared.

Shade matching: After each 1000 meter sample is cut then it is packed with poly bag.

Then it goes to carbolite for drying. After that wash & soaping is done. Finally drying then shade is checked in light box.

Solution of Dyeing Fault

Different types of fault can arise during dyeing which can be solved by the following process:

1. Tropping
2. Stripping

Tropping: In dyeing process firstly the color is matched in lab in it comes to production.

During production at first a sample is run. If it match then goes for production. But still few problems arise after few meters due to uneven picking shade is varied from original one. It becomes lighter or darker. Some times more reddish or greenish. This type of problem is solved by tropping.If the shade is lighter then addition is done & darker dilution can be done. But during tropping the ratio of dye & chemical is 1:4. A typical Recipe of tropping:

128×56/16×10 twill fabrics dyed in CPB. 15% light.

1. Nova yellow NP:0.5 gm/lt
2. Nova red CP: 0.5 gm/lt

iii. Soda Ash -15 gm/lt

1. Caustic -5 gm/lt
2. Albaflow pad (wetting)-2 gm/lt

Stripping: If the shade is widely varied from the original one then the fabric goes through stripping. It is the process by which the color of dyed fabric is removed & makes it white for redyeing. The fabric strength become lower for that additional hard finish is required. Another problem is a stripe fabric can only dyed in dark shade, light shade is not possible.

Typical recipe of stripping: 128×56/16×10 twill reactive dyed

1. Caustic: 20 gm/lt
2. Hydrise:30 gm/lt

This recipe is not constant. It varies continuously based on color & quality of stripe required.

Cold pad batch (CPB):

Chemical and condition-

Chemical	Composition
Dye	As per requirement
Urea	50 g/l when dye is with in 15 g/l   100 g/l when dye is above in 15 g/l
Caustic 30° Be´ strength	(4-14) ml/L according to dye quantity
Soda ash	10 g/l when dye is with in 15 g/l   20 g/l when dye is above in 15 g/
Wetting agent	2 g/l (used when absorbency of fabric is poor)

Chemical and condition (for two bath method):

Chemical for poly part	Composition
Dye	As per requirement
Ant migrating agent	10 g/l
Acetic acid	0.5 g/l
Dispersing agent	(3-5) g/l

Thermal condition for poly part:

Drying temperature –      140 °C for 2 min

Curing temperature-        150 °C for 1 min

Chemical for cotton part	Composition
Dye	As per requirement
Anti migrating agent	10 g/l
Urea	50 g/l (for light shade)   100 g/l (for dark shade)
Soda ash	(10-15) g/l
Lyoprint RG	2 g/l
Wetting agent	1 g/l (when absorbency is poor)

Thermal condition for poly part:

Drying temperature –      (120/130) °C for 2 min

Curing temperature-        (150/160) °C for 1 min

Chemical and condition for one bath method:

Chemical	Composition
Dye	As per requirement
Borax	3 g/l
Lyoprint RG	3 g/l
Dispersing agent	3 g/l
Leveling agent	1 g/l
Anti migrating agent	10 g/l
Urea	50 g/l
Sodium bicarbonate (NaHCO3)	10 g/l

Thermal condition for poly part:

Drying temperature –      120 °C for 2 min

Curing temperature-        210 °C for 1 min

Grey Inspection

Here grey fabrics are inspected according to “four point System”

The 4 point system is done according to American Apparel Manufacturer Association (AAMA). This system is used for determining the fabric quality and fabrics defects are assigned based on point’s values.

It helps to find out the number of defects point in 100 Sq. yds.

Faults / Size of defects                              

1. 3 inches or less 1 point
2. Over 3’’ but not over 6’’ 2 point
3. Over 6’’ but not over 9’’ 3 point
4. Over 9 inches 4 point

In 4 point system

Total points × 36″ ×   100

Points per 100sq. yds =    ——————————————————–

Fabric width in inches * Fabric length in inches

But less than 40 points per 100sq. yds are acceptable level.

Grey fabric Faults:

Name of faults	Causes
1. Starting Mark	It is also called stop mark and happened due to hurt of shuttle in warp and weft and disconnect of electricity.
2. Miss Pick	It is happened due to incorrect Sequence of weft insertions.
3. Double Pick	It causes due to insertion of two picks in a shed during where only one is intended and appear as a line across the width of fabrics.
4. Loss yarn	It caused for low tension.
5. Slubs	It is happened for abnormally thick place in a yarn.
6. Yarn Contamination	Yarn contamination is occurred for mixing of other yarn with the standard unexpectedly.
7. Defective Selvedge	It is caused for bad selvedge and strength loss.
8. Oil Spot	Caused due to grease oil etc.
9. Black Spot	It is occurred due to dirty environment of working.
10. Fungus Spot	It is caused due to contamination of fungus.
11. Size Stained	Result of improper sizing.
12. Shadding	Transverse defects causes by structural distortion.
13. Mending	It is happened due to lack of skilled manual needle  work operation and  faults of checking process.
14. Float/Zahala/Hold/Tear	It is the result of some interference with the opening of the shed and local incorrect interlacing of warp and weft threads in woven fabrics.

Specification of Cold Pad Batch Dyeing Machine

Speed: 20 m/min

Temperature :- 1) For Reactive – 50-60’C, 2) For Disperse – 80’C

Dye padding: – 50% Chemical, 100% Dyes

Recipe: 1) Dyes, 2) Caustic soda,3) Soda ash, 4) Urea

1. Dyeing with silicate:

1. Na Silicate (38 Baume) 50 gm/lt 50 gm/lt   50 gm/lt
2. Caustic (36 Baume) 15 gm/lt 20 gm/lt   30 gm/lt

iii. Albaflow pad (wetting)     2 gm/lt    2 gm/lt     2 gm/lt

2. Dyeing without Silicate:
3. Soda Ash 15 gm/lt
4. Caustic 5 gm/lt

iii. Albaflow pad (wetting) 2 gm/lt

Dyestuff requirement: That will depend on shade required.

Flow chart of Cold Pad Batch Dyeing Machine:

Fabric inlet

↓

Dye padding

↓

Batching

↓

Rotating (8-12) hr

↓

Washing

Cold Pad dry chemical pad steam (PD CPS) process

The following process is followed-

• Dyes and auxiliaries based on the base recipe are weighted using a balance or with an electronic pipette.
• Weighted dyes are mixed with 500 ml of water and stirred for 2 min.
• According to the quality of the fabric padded Mathis is adjusted (usually 60% pick up). Than the sample fabric is set in the machine and dye liquor is poured in for padding.
• The padded sample is put on a frame and than in the Mathis drying and curing machine and then set time and temperature. The sample is dried and takes from the frame.
• The dried fabric is put on the padded machine with chemical pad solution for padding again.
• The padded fabric is then steamed in the Mathis steaming machine at 120 °C with standard steam for 1 min.
• Next the sample is washed based on the washing condition.
• Than the sample is dried using an iron.
• It is than set in the light box and inspected for color matching.
• If the color match with the customer sample than the trial ends and the sample is developed; if not then the recipe id adjusted and trial is continues following the same process until a sample match happens.
• Trial information is noted and each trial sample is attached on the lap dip worksite.

Washing condition:

Cold wash for 1 min

↓

Hot wash with detergent at 90 °C for 1 min

↓

Hot ringing

↓

Cold ringing

Cold pad batch (CPB):

The following process are followed-

• Dyes and auxiliaries based on the base recipe are weighted using a balance or with an electronic pipette.
• Weighted dyes are mixed with 500 ml of water and stirred for 2 min.
• According to the quality of the fabric padder Mathis is adjusted (usually 60% pick up). Than the sample fabric is set in the machine and dye liquor is poured in for padding.
• The next step is for fix the color. Padded sample is put in polythene bag for 5 min. Than a sample piece of that fabric is cut from the sample for rapid fixation test by microwave woven. The sample is hanged on a glass rod over the vassal containing about 50 ml of water and covering the sample and the vassal with a lid. At power of 2 setting. The sample is steamed for 6 min.
• For the color fixation there are two methods. In one method the padded fabric wrapped for 8 hr with polythene bag. In the other method which is rapid process, microwave woven is used. Here the dyeing piece should be kept in the microwave woven (power of 2) in plastic vassals with 50 ml of water for 6 min.
• Next the sample is washed based on the washing condition.
• Than the sample is dried using an iron.
• It is than set in the light box and inspected for color matching.
• If the color match with the customer sample than the trial ends and the sample is developed; if not then the recipe id adjusted and trial is continues following the same process until a sample match happens.

Washing condition:

Cold wash for 1 min

↓

Hot wash with detergent at 90 °C for 1 min

↓

Hot ringing

↓

Cold pad batch dyeing ringing

Dr. Wiliam, Lecturer, USA