Knit dyeing faults and it’s remedies

WELCOME TO THE PRESENTATION

ONKnit Dyeing Faults and It’s Remedies

Submitted ToRajib Saha

Assistant ProfessorDepartment of Textile Engineering

Name : MAZADUL HASAN SHESHIRID: 2010000400008Batch: 13th Batch (Session 2009-2013)Department: Wet Processing Technology Email: [email protected]: www. Textilelab.blogspot.com Southeast UniversityDepartment of Textile Engineering

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INTRODUCTION

Dyeing is a process of treating fabrics with dye liquors which contains both dyestuffs and chemicals and fixing the dyes in the fabric subsequently.

In discussing faults which can be attributed to dyer and finisher, it is necessary first to have a general conception of some of the major operations to which goods are subjected after they are received by the finisher of wet processing .

OBJECTIVES To know about the different types of wet processing

faults. To know about the causes of different types of wet

processing faults. To know about the remedies of different types of wet

processing faults. To know about the pre-treatment process of textile

goods. To know about the wet process of textile goods. To know about the finishing process of textile goods. To know about the different types of wet processing

machineries. To know about the job sequence of wet processing

industry.

FLOW CHART OF KNIT DYEINGGrey Fabric

Stitching

Singeing

De-sizing

Scouring and Bleaching

Dyeing

Finishing

Open Fabric

Slitting

Stanter

Compactor

Tube Fabric

Dewatering

Dryer

Compector

Inspection

Packing

Delivery

Some Faultsin

Knit Dyeing Processing

Description of wet processing faults has been found in knit dyeing:

Faults Name Faults Sample

Incomplete Scouring

Causes Remedy

Too Low concentration of scouring chemical

Too Low scouring temperature and time

Ineffective surfactant / wetting agent

Optimum concentration of scouring chemical.

Optimum scouring temperature and

Time. Effective surfactant / wetting

agent.


Low degree of whiteness

Causes Remedy

In adequate concentration of H2O2.

Too low bleaching pH. Too low bleaching time and

temperature.

Optimum concentration of H2O2

Optimum bleaching pH. Optimum time and temperature.


Effect of H2O2 residues

Causes Remedy

H2O2 residues remove not properly

H2O2 killer agent dosing not properly

Not properly H2O2 killer runtime

Running in alkaline condition.

H2O2 residues remove properly H2O2 killer agent dosing properly Properly H2O2 killer runtime H2O2 killer agent runtime must in

acidic condition.


Effect of Hairiness

Causes Remedy

Not properly enzyme dosing High temperature enzyme

Runtime pH not properly controlled Short runtime of enzyme wash When spoil of enzyme activity

Required amount of enzyme dosing Temperature control properly pH controlled must be 4.5- 4.7 Full time of enzyme run Properly enzyme stored in below

25tem.


Barrie

Causes Remedy

It may be caused by variation in the size of the filling yarn

By the differences in tension of either the filling or warp yarn

Variation in drawing ratio in spinning

Temperature variation during fixation process

Exactly size of filling yarn Properly tension of yarn Proper thermo fixation process Selecting dyes and leveling agent

which are not affected by the temperature variations.


Shade bar

Causes Remedy

It may be caused by a change of filling bobbin in the loom or a loom stop and start up.

It is a horizontal band of a different hue running across the fabric.

Properly change of bobbin.


Uneven dyeing

Causes Remedy

Uneven pretreatment (uneven scouring & bleaching).

Improper color dosing Using dyes of high fixation

property. Uneven heat-setting in case of

synthetic fibers. Lack of control on dyeing m/c.

By ensuring even pretreatment By ensuring even heat-setting in case of

synthetic fibers. Proper dosing of dyes and chemicals. Proper controlling of dyeing m/c.


Line mark

Causes Remedy

Long time store in the floor Dyeing process not properly Extra tension on the fabric

Properly stored in the after dyeing Exactly dyeing process control Tension less fabric run in the dye bath


Batch to Batch

Shade variation

Causes Remedy

Fluctuation of Temperature. Improper dosing time of dyes

and chemicals. Batch to batch weight variation

of dyes and chemicals. Dyes lot variation.

Use standard dyes and chemicals. Maintain the same liquor ratio. Follow the standard pretreatment

procedure. Maintain the same dyeing cycle. Identical dyeing procedure should be

followed for the same depth of the shade.


Dye spot

Causes Remedy

Improper Dissolving of dye particle in bath.

Improper Dissolving of caustic soda particle in bath.

By proper dissolving of dyes and chemicals.

By passing the dissolved dyestuff through a fine stainless steel mesh strainer, so that the large un-dissolved particles are removed.

Causes Remedy

Poor opening of the fabric rope.

Shock cooling of synthetic material

If pump pressure and reel speed is not equal.

Due to high speed m/c running.

Maintaining proper reel speed and pumps speed.

Lower rate rising and cooling the temperature.

Reducing the m/c load. Higher liquor ratio.


Crease mark


Roll to roll variation or

meter to meter variation

Causes Remedy

Poor migration property of dyes.

Improper dyes solubility. Hardness of water. Faulty m/c speed, etc.

Use standard dyes and chemicals. Proper m/c speed. Use of soft water.


Thick –thin yarn

Causes Remedy

If thick/thin yarn is used for making a fabric.

Used of immature fiber. Used of short staple length of

fiber.

After dyeing this type of problem cannot be removed but can be avoided by not mixing the thick/thin yarn in a single fabric.


Off shade

Causes Remedy

It refers to color that does not exactly match the standard or the prepared sample.

This may be due to faulty dyed foundation or application or may be due to variation in dye lot.

Properly select of dye. Correctly fabric lot selection.


Insufficient hydrophilic

Causes Remedy

Insufficient removal of grease, wax and sizing film which gives hydrophobic characteristics to the fabric. When a fabric with un uniform hydrophilic is dyed, areas with different lower / hydrophilic results in a lighter shade are obtained due to the lack of absorption of the dye liquor.

To avoid this a thorough pre-treatment is a must,

Wetting agent can be used in dyeing liquor.


Bowing

Causes Remedy

Woven filling yarns lie in an arc across fabric width; in knits the course lines lay an arc across width of goods.

Establish standards of acceptance .Critical on stripes or patterns not as critical on solid color fabrics.

Uniform sewing is required. Equal width fabric is required. Proper tension fabric passes in

compactor.


Compacting crease

Causes Remedy

Excessive apply on Teflon pressure.

Less tension roller. Uneven temperature of two

cylinders.

Minimum required of Teflon pressure. Exact setting of tension roller. Exact setting of temperature in cylinder.


Water spot

Causes Remedy

Fixation with a few drop of water on specific area of dyed fabric

Proper fixation


Poor washing fastness

Causes Remedy

Inadequate washing of hydrolyzed dye.

Inadequate removal of loosely retained dye.

Inherent low fastness properties of the dye.

Optimum washing off. Use of cationic fixing agent or other

fastness improving after treatment.


Oil & Grease Spot

Causes Remedy

During dyeing and finishing process sometimes oil and grease may fall on fabric which may cause oil and grease spot on the dyed fabric.

Due to careless transport of dyed or finished fabric.

Must be careful about oil and grease during dyeing and finishing process.

Must be careful about the transportation of dyed or finished fabric.

With immediate application of spot –lifter.


Pilling effect

Causes Remedy

Pilling is a common fabric occurring on knitted and woven fabrics.

In producing a yarn fibers tightly twisting produce a serviceable yarn. When short stable fibers are mixed into the yarn the result is a yarn that will not together. The short staple fibers will separate from the yarn and curl up in a ball,- forming what is referred to as a pill.

Pilling is accentuated by the friction of normal wear, washing and routine dry cleaning.

Exactly maintain of enzyme wash. Evenly mixing of short staple fibers. Properly twisted of yarn.

CONCLUSION

Two months industrial training at Alim knit tex (Mondol Group) Ltd, Metro Knit and Dying Mills Ltd, Square Knit Fabrics Ltd. were a part of B.Sc. in Textile Engineering course. During the training period the whole 60 days were segmented and scheduled to a systematic routine. There was different faults operation in textile wet processing.

It should be mentioned that Alim knit tex (Mondol Group) Ltd, Metro Knit and Dying Mills Ltd, Square Knit Fabrics Ltd. are 100% export oriented knit dyeing industry .To produce a quality product above all export quality it could be desirable that the process should be high standard.

Here we have some limitations in our training period, and two months are not enough time to complete the knowledge about the textile terms.

Documents

Knit dyeing faults and it’s remedies