TEXTILE FINISHING MATERIALS

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• Textile wet processing can be thought of having three stages, pretreatment (or

preparation), coloration (dyeing or printing) and finishing.

• Finishing in the narrow sense is the final step in the fabric manufacturing

process, the last chance to provide the properties that customers will value.

Finishing completes the fabric’s performance and gives it special functional

properties including the final ‘touch’. But the term finishing is also used in its

broad sense: ‘Any operation for improving the appearance or usefulness of a

fabric after it leaves the loom or knitting machine can be considered a finishing

step’.

• Physical properties such as dimensional stability and chemical properties such

as flame retardancy can both be improved with chemical finishing. Typically, the

appearance of the textile is unchanged after chemical finishing. Mechanical

finishing or ‘dry finishing’ uses mainly physical (especially mechanical) means to

change fabric properties and usually alters the fabric appearance as well.

Mechanical finishing also encompasses thermal processes such as heat

setting (thermal finishing).

• Textile Finishing is any operation (other than preparation and colouring) that

improves the appearance and/or usefulness of fabric after it leaves the loom or

knitting machine. Finishing is the final series of operations that produces

finished textile fabric from grey goods. Textile finishing usually includes

treatments such as scouring, bleaching, dyeing and/or printing, the final

mechanical or chemical finishing operations etc.

• Textile finishing usually includes treatments such as scouring, bleaching, dyeing and/or

printing,the final mechanical or chemical finishing operations, that during this stage are

carried out on textile products (staple, sliver or top, yarns or filaments, woven or

knitted fabrics) to enhance their basic characteristics like dye penetration, printability,

wettability, colour, hand, and appearance.

• By textile finishing, we also mean all the processing operations that, though included in

the so-called finishing stage, are generally applied to the fabrics to improve their

appearance, hand and properties, at times in accordance with their field of application.

• The finishing stage plays a fundamental role in the excellency of the commercial

results of textiles, which strictly depend on market requirements that are becoming

increasingly stringent and unpredictable, permitting very short response times for

textile manufacturers.

• Have you seen a fabric that comes from a loom? It is generally rough to feel,

dirty with stains and is known as ‘gray cloth’. The ‘markin’ fabric which we buy

for making quilt covers is off-white and dirty and is a gray fabric. But most of

the other fabrics that we buy from a shop are smooth, neat and clean. Why and

what happens in between? Yes, a finish has been applied.

A finish is anything that is done to a fabric after weaving or knitting, to changes

its appearance, hand and performance. When a finish is applied, say on cotton, it

might become more shiny, stronger or resist shrinking on washing. Similarly,

other finishes may make the fabric softer or stiffer; water or stain resistant;

coloured or designed.

Aim of Finishing

• The final chemical treatments of the fabric which are carried out to

impart special characteristics e.g. softening, stiffening, crease

resisting, flame retarding, soil release effect etc. is known as textile

finishing. The aim of the finishing is to improve the outward

appearance and the quality of the fabric, and impart its specific

properties.

General

Requirements

of Chemical

Finishing

Cycle of Finishing Process

• The whole cycle of finishing consists of mechanical and chemical processes,

which are used depending on the kinds and end uses of the fabric. Mechanical

processes include drying, calendaring, schreinering, embossing, sueding,

raisingetc and chemical processes include in the application of special

substances on the fabric, impregnation with size, starch, dextrin and other

polymeric substances. Plain fabrics (bleached, dyed and printed) are subjected

to finishing and other kinds of treatment. For instance white printed fabrics

with a white ground are passed through a padder containing a solution of

optical whitening agents for imparting glassy effect to the fabrics to be printed.

Mechanical treatments

• Drying

• Steaming

• Tentering

• Sanforizing

• Raising

• Calendaring/Schereinering/Embossing

• Perforating and slitting

• Shearing

Chemical Treatments

Temporary chemical treatments:

• Hardening

• Softening with non-fabric reactive finishes

Permanent chemical treatments:

• Anti-crease finish

• Anti stats

• Antimicrobials

• Lubricants

• UV absorbers add polymer stabilizers

• Thermoplastic binders, resins and emulsion polymers

• Thermosetting resins and crosslinking agents

• Softening with reactive polymer

• Durable flame retarding

• Durable water repelling etc.

Textile Finishing Processes

• The whole cycle of finishing consists of mechanical and chemical processes,

which are used depending on the kinds and end uses of the fabric. Mechanical

processes include drying, calendaring, schreinering, embossing, sueding,

raisingetc and chemical processes include in the application of special

substances on the fabric, impregnation with size, starch, dextrin and other

polymeric substances.

Steaming

• A fabric steamer uses steam rather than heat to remove wrinkles. The steam,

and slight pressure of the steamer's surface, relaxes the fibers rather than

flattening them. Because of this process, using a fabric steamer is gentler on

clothing, faster than using an iron, and eliminates scorching. The fabric steamer

is ideal for use on napped fabric, such as velvets and velveteen. A traditional

iron will crush the nap, unless used with a needle board, but the fabric steamer

doesn't exert pressure, preserving the luxurious look and feel of any material.

Even very delicate materials, such as satins and silks, benefit from the gentle

care of a fabric steamer.

Sanforizing

• It is a process whereby the fabric is run through a sanforizer; a machine that

has drums filled with hot steam. This process is done to control the shrinkage

of the fabric.

Tentering

• It is the mechanical straightening and dying of the fabric. Tenter fames hold the

fabric with special pins. The chain is spread apart to the desired width of the

fabric. The fabric is moved through dying units. Later the fabric is rolled on

cylinders.

Calendaring/Embossing/Crabbing

• Fabric calendaring is effected in special machines I.e. calendars, the main working

organ of which is rolls with smooth surface for normal calendaring engraved surface

for emboss calendaring and engraved finer lines for schreinering calendaring or for

getting crepe effect. The calendar may be 3 bowl or five bowl and the contacting one

bowl is plain steel roller and the other may be covered with rubber otherwise the

fabric at nip point will break if both bowls are hard.

• Glazing or rolling calendar: This method is not particularly important for nonwoven

fabrics, with occasional exceptions. The smooth surface can be obtained usually by

selecting an appropriate form of bonding and, especially, for drying a wet-bonded web.

Calendaring has not met with much success since it is often accompanied by

undesirable compression. The only time a rolling calendar is used is when two steel

rollers are paired to break the so-called 'blotches' in spun-bonded fabrics.

• Moiré or goffering calender: The calenders are common in nonwoven finishing and are

used in the compacting of the webs made of natural and synthetic fibers. This type of

calendering can be considered to be both a bonding and finishing process. Webs

composed of longitudinally oriented cotton or viscose fibers with a GSM of about 10-

30 g/m2 can be stiffened and compacted sufficiently by passing them through a

goffering calender when slightly damp. Hot embossing of synthetic fiber webs, even

when the fibers are longitudinally oriented, produces a product remarkably strong due

to the fibers melting at the embossed areas. The patterns can be of grid, webbed or

point type. The temperature of the heated rollers is generally 20-30°C above the

melting point of the fibers and the nip roll pressure 20-50dN/cm, depending on the

volume of the web and the proportion of synthetic fibers it contains. If the web is

cross-laid, point embossing results in maximum strength. If the fibers are arranged

lengthwise, webbed embossing is employed.

• The embossing effect is used to obtain special effects such as leather graining,

simulated weave, plaster, brush strokes, cord and mock tiling. Another area in

which heated calenders used is in the manufacture of laminates. Here

thermoplastic fibers, layers of thread or film are placed between two layers of

non-plastic web and are fused together by heat and pressure. Such laminates

are used as tablecloths, seat and cushion covers. Calenders are also used in the

transfer printing of the bonded webs.

• Crabbing is a preliminary treatment for both un-dyed and dyed woven fabrics

with differing objectives. In the case of un-dyed woven material the crabbing

process serves to fix the fabric so as to avoid too intensive creasing and felting

at the subsequent dyeing stage. After being dyed the woven fabric is smoothed

and leveled by crabbing. Silicone blankets are used in this process.

Perforating and Slitting

• The nonwoven bonded fabrics produced are too stiff and are, therefore, unsuitable for clothing.

This is because the individual fibers are not free to move in relation to one another, as are

threads in woven or knitted fabrics. Perforating and slitting are two methods practiced to

improve the fall or drape of nonwoven bonded fabrics.

Perforating:

• The Artos method is a method of perforating in which the web, which has been bonded by

using chemicals, is perforated with hot needles. This process not only punches holes but also

reinforces as a result of cross-linking and condensation of the bonding agent. The Hungarian

firm Temaforg uses a similar method to perforate webs made of synthetic fibers to produce

nonwoven bonded fabrics which are strong and yet supple enough for use as building and

insulation materials.

Slitting

• Slitting originally developed to improve the softness and drape of films was

used by the Breveteam Company for interlinings, in particular for adhesive

fixable interlinings. The optimum cut length and distance between the slits to

get maximum softness and fall without serious reduction of strength can be

calculated. The effect of slitting allows greatest flexibility at right angles to the

direction of the slit.

• The slitting is accomplished by a roller with small blades mounted on it, for

example, in an off-set arrangement 1.7 mm apart, making slits of a maximum

length of 6.5mm. Rotary knives with spreaders can be fitted to the roller, thus

making an interrupted cutting edge. Polyethylene or polyamide film shaped by

splitting or embossing and stretching by the Xironet and Smith-Nephew

methods make good air permeable bonding layers.

Distribution of

finishing product

groups by

amount and

value.

Anti-crease finish

• For getting anti crease effect usually melamine formaldehyde, urea formaldehyde and

dimethylol dihydroxy ethylene urea (DMDHEU), butane tetra carboxylic acid (BTCA) etc. can

be used. At very high temperature, they react with cellulose and give permanent anti crease

effect.The following reactions take place between the cellulose macromolecule and DMDHEU

• The usual method is Padding with DMDHEU and Catalyst -> Drying at (90-100)

degree C for 5 minutes -> Curing at (140-150) degree C 5-3 minutes

The following recipe can be used:

• Stabitex FRD/Fixapret CPN (DMDHEU) = 75 g/L

Ploy Vinyl acetate = 20 g/L

Ammonium sulphate = 10 g/L Or Magnesium Cholride = 10 g/L

Sodium perborate = 0.3 g/L

• The fabric is padded with the above solution and then dried at 100 degree C following curing

at 160 degree C for 3 minutes. Curing can be carried out in the stentering machine or curing

chamber.

Antistats

• Static electricity tends to build up in nonwovens made of synthetic fibers due to their lack of

moisture regain and conductivity. This can cause problems such as clinging and dragging during

processing, apparel that clings and crackles, dangerous discharge of static electricity in

explosive atmospheres and tendency to attract airborne dirt and soil in processing and use.

• The antistats work in three basic ways. They improve the conductivity of the fibers, coat the

fiber with a thin layer of material that will attract a thin layer of moisture, and finish the fabric

such that it holds a charge opposite to that normally accumulated on the fiber to neutralize

the static charge. Antistats can be either durable or non-durable. Examples of durable antistats

include vapor deposited metals, conductive carbon or metallic particles applied by binders,

polyamines, polyethoxylated amine and ammonium salts and carboxylic salts. Non-durable

antistats usually consist of inorganic or organic salts or hygroscopic organic materials.

Examples are quaternary ammonium salts, imidazoles and fatty amides which are cationic.

Anionic antistats include phosphates, phosphate esters, sulfonates, sulfates and phosphonates.

Examples of nonionic antistats include glycols, ethoxylated fatty acids, ethoxylated fatty

alcohols and sorbitan fatty acid esters.

Antimicrobials

• These are used to control populations of bacteria, fungi, algae and viruses on the substrate. The

treatment usually prevents the biological degradation of the product or prevents the growth of

undesirable organisms. Broadly classed, the antimicrobials are either fixed or leachable. The

fixed treatments are durable, but the leachable treatments may transfer to the surrounding

environment through migration, solubility or abrasion. A generic list of the treatments include

alcohols such as isopropanol or propylene glycol, halogens such as chlorine, hypochlorite,

iodine, N-chloramine and hexachlorophene, metals such as silver nitrate, mercuric chloride and

tin chloride, various peroxides, phenols quaternary ammonium compounds, pine oil derivatives,

aldehydes and phosphoric acid esters. Care should be taken in the application of these

compounds to prevent inactivation, loss of durability or masking of the active ingredient with

other finishes.

Lubricants

• Lubricants or slip agents are generally applied as processing aids to help in

stretching or to improve the process ability of nonwovens. They are also

applied to aid in sewing, quilting, tufting or other processes where needles

penetrate the fabric. Lubricants impart the same properties as softeners but

specifically reduce fiber friction. Common chemicals include sulphonated oils,

oil emulsions, silicones, esters, polyethylene dispersions and fatty acid soaps.

Many surfactants may also be used. Care should be taken to avoid excessive

strength loss.

UV absorbers and polymer stabilizers

• Ultraviolet light can do great damage to the polymers causing photo-

degradation, yellowing, loss in strength and fading of the colors. The damage is

generally due to the formation of destructive free radicals in the polymer. The

finish can protect the fabric by shielding the fiber or absorbing the light or by

chemically quenching the free radicals. The three main classes of products used

are, substituted benzotriazoles, benzophenones which are UV absorbers, and

hindered amines which are free radical reactants. They are applied from a bath

or added to the polymer.

Thermoplastic binders, resins and emulsion polymers

• Binders and resins are widely used in the finishing of nonwovens to add

strength, control stiffness, add mold ability or pleat ability, provide durable

flame retardants, color, reduce linting and control shrinkage. They soften when

exposed to heat and return to their original state when cooled and, hence, can

be set. Emulsion polymers are also called latexes. The common binders, resins

and polymers include acrylics, PVC, poly-acrylic acid, urethanes, starch, vinyl

acetate etc.

Thermosetting resins and crosslinking agents

• These are used to produce wrinkle resistant or permanent-press textiles. They

are used to crosslink cellulose for wrinkle resistance, crosslink binders for

wash durability and solvent resistance. The technology is based on the ability of

formaldehyde to react with cellulose and nitrogen containing resins. The

important resin types are melamine-formaldehyde, urea formaldehyde and

dimethyloethylene urea. The reaction is usually catalyzed by acids, such as

Lowry-Bronsted or Lewis acids. Problems encountered include formaldehyde

generation, tensile loss, discoloration and amine odor.

Softening

To impart softness, smoothness and flexibility it is necessary to apply a softening

agent. According to ionic nature softener can be classified into:

• Anionic softener

• Cationic softener

• Amphoteric softener

• Non ionic softener

• Among them, cationic softeners are mostly used because most of the textile is

anionic in nature. Therefore cationic softeners have a god affinity towards

textile fibers.

The following recipes can be used:

Basosoft 8 kg

Glycerine 1 kg

Water as required

Stentering speed 45-60 m/min

Temperature in different chambers of the stenter m/c

1st chamber 180°C

2nd chamber 180°C

3rd chamber 190°C

4th chamber 210°C

5th chamber 170°C

Stiffening Treatment

To impart hard or stiff handle it is necessary to apply a softening agent .For stiffening treatment

the following chamber chemicals can be used.

• Starch or modified starch

• Polyvinyl acetate(PVA)

• Polyethylene Emulsion

Recipe:

• Perapet PE 40(polyethylene) 10 Kg

• Water 90 Kg

• Temperature 220 °C

• Fabric speed in stenter 40-60 m/min

• Pressure in Padder 4.5 kg/cm