WET PROCESSING TECHNOLOGY-II; TEX: 303

SECTION: ATOPIC: THE ROLE OF FINISHING

PROCESS IN ADDING SERVICEABILITY TO TEXTILE PRODUCTS.

COURESE ADVISERDR. A.K.M. SAIFUL ISLAM

HEAD OF THE DEPARTMENT OF B.S.T.E

GROUP MEMBERS

NAME ID

MD. EMAM HOSSAIN

MD. TAJUL ISLAM

MD.RIYAZ -UL- ISLAM

06313222

06313085

06313241

AHSAN HABIB

MASHIUL AZAM RASEL

AHAMMAD AL NAHIAN

06313269

06313171

06313094

Textile finishing is process to improve serviceability of the colored product, or Finishing is done to improve a product’s appearance, properties and quality.In short sense, finishing is the process by which the fibres, yarns, fabrics are made as presentable to the customer and these process are implemented after coloration.

Introduction

Classification of Finishing:

The finishing process which is performed by machines but not using of chemicals is called mechanical finishing.

Comparatively less permanent effect. Less expensive. To improve appearance and handle etc. Example: raising, sanforizing etc.

Physical / Mechanical finishing:

Chemical finishing:

The finishing process which is performed by application of chemicals which reacts with fibres is termed as chemical finishing. Comparatively more permanent effect. More expensive. To improve performance.

Example: mercerizing, resin finishing etc.

Raising:

The process raising produce particular effect on fabric which is termed as,

Funnel fabric (woven raised fabric).

Fleece fabric (knitted raised fabric).

By the process raising layers of fibres are lifted or raised and thus make funnel or fleece effect.

Teasel filled frames are placed on a drum which rotates and the fabric is brought into careful contact with the teasel filled frames. Raising must take place very gradually and the fibres are really untangled and lifted instead bring torn from the surface of the fabric. The rotation of cylinder of the machine in the same direction as the fabric but at a higher surface speed. Obviously the number of runs depends on the nature of the material and the effect required.

Raising procedure:

The objects of raising are mentioned below,

To obtain a lofty handle effect in fabric. To obtain fleecy appearance. To create pile or cover on fabric surface. To produce a heavier surface made of fibres. To produce warm cloth as well as a soft one. Raising effect can be obtained in two ways,

I) Teasel raising.II) Card wire raising.

Objects of raising:

Teasel is a kind of substance having very sharp edge at end (look like pin). It grows on a thistle plant. The average length of teasel is 15 to 175 inches. Some teasels are 2 inches long. King teasels are 4 inches long.

i) Teasel raising:

ii) Card wire raising:

Card wire raising machines are constructed on a cylinder aroundwhich one or two sets of small rollers are assembled. Smallrollers are covered with wire filleting.

Two main types of machine are available,

a) Single acting machine.b) Double acting machine.

Sanforizing:Sanforizing is a mechanical process of treating textile fabrics to prevent the normal dimensional alternation of warp and weft. Sanforizing is a controlled compressive shrinkage process, which is applied on woven fabric to achieve shrinkage before making the garments. After sanforizing the residual shrinkage of woven fabric may be zero.

Sanforize machine has endless blanket that is stretched over feed rollers.The fabric is introduced between the belt and a drum, while the belt is in the elongated stage.The belt is then allowed to shrink and compresses the fabric with the aid of the steam heated cylinder. Before sanforizing, fabric must be passed through vaporizing unit for moisture regain.

Principle:

Causes of shrinkage:

The major cause of fabric shrinkage is due to the swelling of threads on wetting. The thickened warp yarns require more space to enable them to pass over and under the swollen weft yarns. So they must adopt an undulating path and so the cloth shrinks. The cotton materials are not completely shrunk on the first wash but continue to shrink in further washes. So shrinkage seems to depend on the intensity of washing treatment. Shrinkage also depends on amount of crimp in yarn and fineness of yarn.

Mercerization:The treatment of cotton yarn or fabric with a strong solution of caustic soda (NaOH) is termed as mercerization. The process was named according to its invention ‘John Mercer’. ‘John Mercer’ invented this technique. The findings of John Mercer was that caustic soda caused cotton fibre to swell become round and straight.

Another British man named ‘Lowe’ exercised the John Mercer’s technique under tension.

The finding of Lowe was that treated of cotton yarn or fabric under tension results high luster to the cotton yarn or fabric.

Physio-chemical process of mercerization:

When cotton fibre is brought into aqueous solution of sodium hydroxide of 45˚ Tw (18%), the cellulose begins to swell immediately and in a few seconds the hair/fibre is elliptical in x-section. The cellulose of the wall swells inwards until the lumen is practically eliminated. These charges are shown in the following figure:

Stage 1 to 5 shows progressive swelling in alkali.Stage 6 shows that shrinkage starts on transfer in water. Stage 7 shows final shape of the cross-section after drying.

Objects of mercerization:

I) Increase tensile strength.II) Improved hygroscopicity. III) Improved dye affinity.IV) Improved smoothness. V) Improved luster.VI) Improved dimensional stability and physical compactness.

Mercerization technique:

Caustic soda concentration, temperature of caustic application and dwell time are important factors to consider in the mercerization process. Mercerization is carried out using 20-25% caustic soda solution at around 200c (room temp.) by impregnating cotton yarn or fabric under tension or without tension the introduction of tension will add luster to the yarn or fabric and prevent the loss of length of cotton yarn or fabric.

Resin finishing:

Resin finishing is a permanent chemical finishing. The principle is based on the formation of in finite networks and the quantitative characterization of network structure with cross linking of homogeneous polymers.

Advantages of resin finishing:

Improved wrinkle recovery.Better dimensional stability.Increase in weight is achieved. Easy of ironing. Improved resistant to pilling formation.Increase the strength of rayon in both and cold state. It provides full retention of all creases and pleats.

Disadvantages of resin finishing:

Reduction in strength. Reduced moisture regains. Sewing problems. Discoloration or shade change for some dyes.

Technique used to apply resin finish on fabric:

Example of resin chemicals:

Ingredients used in resin bath:

Resin.Catalyst: to promote reaction.Wetting agent: it helps in saturating the fabric with finish chemicals.Softener: it improves in softness of the fabric.

Conclusion:

Finishing is the process which is mandatory to attract the customers to the product. So the success of a new or any product is largely dependant on the finishing. So emphasize should be give during any finishing. So that it fulfill the customer need thus maintain the reputation of the produces within exceptive expenditure of the process.

Reference Books:Class lecturerWet processing technology Md. Moshiour Rahman. Books Fair Publications, Dhaka Pages – (105,106,109,110,138,146,148).Reference Links:*www.google.com*www.yahoo.com