Mechanical and Chemicals Finishes of Textile

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Description about application of mechanical and chemical finishes on fabrics

Text of Mechanical and Chemicals Finishes of Textile

Finishing of technical textilesDescription of different techniques used in wet processing to develop Technical Textiles Dr Muhammad Mushtaq Mangat Dec 31, 2012

Finishing of technical textiles

Textile Finishing: A process to improve the performance and appearance of textile It may be mechanical or chemicals processes It could be temporary or permanent examples:

Calendering Peaching Raising Coating Deposition of chemicals (fire retarding)

Mechanical finishes

Calendering Modification of fabric surface by passing fabric through hot roller Rollers may be engraved or polished

Purposes of calenderingsmoothing the surface of improving the handle of the fabric, a fabric, i.e. softening increasing the fabric


closing the threads of a

flattening slubs gloss finishes

woven fabric permeability opacity

obtaining silk-like to high

decreasing the air increasing the fabric

surface patterning by embossing nonwovens. [1]

consolidation of

Flattening effect on fabric of calendering

Calender definition and process

A mechanical process to impart certain

temporary or permanent effects on web, fabric or batt normally hot

Material is passed through a nip of rollers, Rollers may be plane, polished, covered with

fabric, engraved, embossed

Calender parameters

Calender speed (dwell time in nips) Temperature of calender Pressure of rollers (pressure per linear


Surface of rollers (polished, covered) Speed variation between bottom and

top rollers

Number of passes Over Feeding or under feeding

Calendering and Application of finishes

Dry Calendering without application of


Drying and Calendering together

Pad Mangle and Calendering


Calendering of fabrics made by natural and synthetic fibers

Natural fibers Need high pressure to defeat the physical memory and get a new shape, temperature role is less important than pressure Strength of web depends upon the cohesion of fibers, need high pressure to achieve a certain homogeneity

Synthetic fibers Synthetic fibers require the presence of heat to defeat the physical & thermal memory of the fiber High temperature and low pressure are commonly in practice Speed of rollers should be same to avoid any un-wanted luster [2]

Rolling Calender for synthetic fibers [2]

Rolling Calender

It provides:

smooth or gloss fabric surface Reshape fibers, make them flatten and increase cohesion by more tightly stack around (nestle effect) Composed of three rollers 100-150 meter per minute for normal fabric and 30-35 for nonwoven Can be run at 3000 PSI Four or five rolls Alternative rolls (polished and filled) The intermediate resilient roll is of wool felt paper, cotton, khaki wool and resilient wool and cotton blends which affords the extension of the webs [2].


It provides a smooth fabric surface, light

luster and improved hand

Provides comparatively soft Combination of small and big roller, provides

wide nip. It will break any stiffness on the surface due to auxiliaries or weaving or knitting

Silk Calender [2]


To give highly polished surface Also creates water repellency Normally used for apparel fabric Friction calender can be operated at

different speeds polished

Set of three rollers,; one filled and two

Friction calender [2]


Used to obtain a controlled opacity, a desired softness luster and translucency Light reflection is changed due to changes on surface Pattern is engraved on the heated steel roll Name derived from the pattern which is 260 lines per inch at a 26 degree angle and only .001 of an inch deep It can consolidate the fibers by as much as 4% to 16% Can be used for natural, synthetic and blended or coated fabrics that are both knit and woven or non woven [2]



Rollers with embossed patterns Can be used for types of fabrics including

woven, non-woven and knitted cloth certain patterns on calender rollers

Desired shapes can be achieved by having Other properties are similar to normal calender Can be used for all sorts of fabrics There are forged steel top roll and a filled bottom

roll with the filling of wool felt [2]

Embossed Calender [2]


The Cir calender is used for glazing and

glossing fabric surfaces using both high temperatures >425 F and high pressures >1500 PLI

Porosity reduction and compaction is done Various types of fabrics can be processed



Also called paper printing machines Purpose is to transfer print from paper to


Hot rollers are used for paper printing Mostly used for polyester fabric Disperse dyes are used

Paper printing rollers


Also called calender bowls Made by using high tonnage of pressure;

120,000 tons of pressure the cotton rings to be able to use as calender

Rollers are quite hard in nature


Raising (Brushing)

Raising is a process in which fabric is brushed with

the help of wired rolls to give a brushed (napped) look

Fibers are pulled from the yarn to make a soft feel and

increased thickness

It gives a hairy surface More air is trapped and thermal resistance increased Rotating rolls tted with wires are used

Fabric Brushing Machine

Raising Methods

Hooked or bent steel wires are used for


Angle, speed and pressure are main factors Number of rotating rollers, width of rollers

define the capacity of machine uniform surface

More than one pass is normally require for



A process in which piles of fabric are cut to

have a uniform and smooth surface is applied

Lawn mover (grass cutter) machine principle

Compressive Shrinkage (Compaction)

Shrinkage on washing is a common


It is due to residual stress or strain in fabric

during process

Very common use Makes fabric more stable and minimize the



Sueding (Peaching)

Sueding Technique


To give a peach look Brush or zero sand paper is used Improve hand feel Better thermal resistance Currently much demanded and in practice

Heat setting

To make a stable fabric Used to ensure that there will be no change

in dimensions

Only used for synthetic fibers Required temperature is above the softening

temperature of fibers heat setting

Certain temperature and time is required for

Heat-setting mechanisms

1. chain stiffness 2. strong dipole links 3. hydrogen bonds 4. crystallization [1]

Influencing factors

Temperature, Moisture, stress. PET fabric is passed through stenter at 180-190 C for 30-60 seconds Sudden cooling effect, called decatizing is done for better setting Little moisture helps for better heat setting In general heat setting temperature is with in 20-2040 C of the fiber melting point. Hold at this temperature under tension for approximately 20 s. Cool fabric before removing tension After heat setting shrinkage should be less than 1% [1]

Transition temperatures

Glass transition temperature: Molecules tarts moving in amorphous region

Substance starts changing from a glassy solid

to a rubbery solid Loosening starts and dyeing is possible

Melting point

Thermal energy increases than holding


Pleated Fabric

Permanent Pleats

To give better look Increase usability Some special purpose fabric is made Common for ladies clothing Bags are produced for more space

Pleat Making Machine

Chemical Treatment

Fire retarding Water repellant Stain proof Ant bacteria, moth proof Self cleaning Flavored Anti pilling Anti slippery

Stiffening and filling process

Polymers are used to create stiffness Stiff effect is required for certain purpose e.g.

collar lining, curtain lining etc. poly vinyl chloride

Most common are poly vinyl acetate and Applied on padding

High Wicking

Wetting agents are used to increase wicking

power of fabric agents

Towels, T shirts, shorts are treated with wetting Applied on exhaust and padding

Anti-static finish

PE is much popular to reduce the static


Improve comfort of clothing Much required for sensitive skin

Anti-pilling finish

Mostly enzymes are used to remove

protruding fibers

Also called bio-polishing Cleans the surface Reduces the chances

Non-slip finishes

To have better grip Rough surface is developed Silica gel is commonly used Gives a crispy hand feel

Fire Resistant or Flame Retardant

Flame retardants are materials which can

minimize the spread of fire area,

For better safety, becoming popular in every Many laws are being formulated to have Fire-

retardant items at work event at homes

Two techniques: Application of chemicals on fabric surface Making changes in fiber t


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