WATER REPELLENT, ANTI STATIC & ANTI BACTERIAL

FINISH.BY

PARAMVIR AHLAWATKISHLAYA KAUSHIK

WATER REPELLENT FINISH:-

•The finish which makes the fabric impervious to water.

•Water Repellent Fabrics have open pores and are permeable to air and water vapors.

•Water-repellent fabrics will permit the passage of liquid water once hydro-static pressure is high

•A fabric is made water-repellent by depositing a hydrophobic material on the fiber‘s surface; however. waterproofing requires filling the pores as well.

•A fabric’s resistance to water will depend on the nature of the fiber surface, the porosity of the fabric and the dynamic force behind the impacting water spray etc.

HOW A FABRIC GETS WET:

•When the surface tension of the liquid is lower than the surface free energy of the solid, the liquid will spontaneously wet the solid.

• Surface free energy of cotton is 44 mN/m.•The surface tension of water is 72.8

This finish gives hydrophobic features to the substrate. There are three main product groups for this finish

• Metal salt paraffin dispersion;• Polysiloxane• Fluorocarbon polymers

They form a film where the fluorocarbon redials are perpendicular to the fiber axis and prevent wetting of the fiber surface.

Their high hydrophobic & oleo phobic action is explained by the extremely low interfacial tension of fluorocarbon chain towards all chemical compounds

Recipe

Dimethyl Dihydroxy Ethylene Urea - 40-60 g/lZirconium salt-containing wax emulsion - 60 g/lReactive Softener - 60 g/lMagnesium chloride. - l0 g/l Pad, dry and cure at 150oC for 5 min.

Typical application fields are:

•Carpet finishing.•Clothing (e.g. sportswear & rain coat.).•Umbrella cloth.•Table linen curtains upholstery fabric.•Tarpaulins and tents. Technical fabrics (e.g. fitter material, fabrics, protective clothing).

Product advantages:

•Durable to washing. Also resistant to dry-cleaning. •Easy handling and storing because it is not inflammable.•Low foaming.•High resistance to yellowing, suitable for colored and white goods.•No influence on the light fastness and the shade

Antistatic finish

•Used for the removal of the unwanted effects of electrostatic charge in synthetic fibers, produced during spinning, weaving and finishing.

•Static electricity found in mostly synthetic fibers e.g. polyester etc.

PROBLEMS ARISES DUE TO STATIC ELECTRICITY:

•The operator at the delivery end of a stenter may get electric shocks because of static electricity.

•Garments made of polyester fibers attract soil during normal wear and also have a tendency to cling to the body of the wearer.

HOW TO IMPART THIS FINISH?

•Non-durable antistatic agents are usually hygroscopic surface-active materials (hygroscopic substances absorb water from the air), closely allied in composition to softeners and wetting agents.

• A permanent antistatic finish is a combination of a cationic and an anionic compound. •Cationic quaternary ammonium compound - 3-4% Acetic acid (30%) - 0.5-1 cc/l •Treat the fabric with the above composition for 10-20 min at 70'C (in a jigger). Then add (anionic alkyl sulphate) - 1.6-2.2% •Continue treatment for another 10-20 min. Dry and cure if required.

IMPARTING ANTISTATIC FINISH AT YARN STAGE:

This process comprising wetting said yarn before it is bulked and dyed with a high temperature stable antistatic agent, forming the wet yarn into skeins, then subjecting the skeins to wet heat at 185° - 205° F. followed by dry heat at 195° - 220° F.

Skeins are dried and then dyeing and bulking the yarn to give a bulked, dyed yarn which has durable antistatic properties

The antistatic agent being the reaction product of

1) A water-soluble polyamine containing polyalkylene oxide groups attached to the nitrogen atom and having in the molecule more than one reactive hydrogen atom attached to a nitrogen atom and

2) A compound containing more than one radical from the group consisting of epoxide and halohydrin radicals.

Applying the antistatic agent directly to fabric containing bulked yarns raises some complications, e.g. the dyeing time must be substantially increased when the antistatic agent is combined with dyeing of the fabric.

Common antistatic agents are based on long-chain aliphatic amines ( optionally ethoxylate) & amides, quaternary ammonium salts (e.g. behentrimonium chloride or cocamidopropyle betaine) , easter of phosphoric acid polyethylene glycol easter or polyolus.

BACTERIOSTAT FINISH:BACTERIOSTAT :A chemical or biological material that inhibits bacterial growth.

•Antibacterial is effective in killing and preventing the growth of both bacteria and fungi known to degrade textile substrates

•Products finished in it have been proved environment friendly and health protecting, preventing diseases. It also prevents garments from unpleasant odour.

•Anti-microbial agents can be applied to the textile substrates byexhaust, pad-dry-cure, coating, spray and foam techniques.

• The application of the finish is now extended to textiles used for outdoor, healthcare sector, sports and leisure

HOW DO BACTERIAS GROW?

•Spores of fungi and bacteria exist everywhere and under hot and humid conditions these rapidly multiply feeding on their hosts. These microorganisms attack the natural fibres as well as the finishes applied to these and cause mildew and rotting damages.

•Natural fibers such as cotton are more susceptible than synthetics because their porous hydrophilic structure retains water, oxygen and nutrients, providing a perfect environment for bacterial growth

•The enzymes that degrade cotton are cellulase and cellobiase and these reduce strength and produce colored and foulsmelling spots and even holes on the exposed fabric

Antimicrobial treatment for textile materials is necessary to fulfill the following objectives:

•To avoid cross infection by pathogenic micro organisms.

•To control the infestation by microbes.

•To arrest metabolism in microbes in order to reduce the formation odour.

•To safeguard the textile products from staining, discolouration and quality deterioration.

Requirements for antimicrobial finish:

•Durability to washing, dry-cleaning and hot pressing.

•Selective activity to undesirable micro organisms.

•Should not produce harmful effects to the manufacturer, user and the environment.

•Should comply with the statutory requirements of regulating agencies.

•Compatibility with the chemical processes.

•Easy method of application. No deterioration of fabric quality.

•Resistant to body fluids; and resistant to disinfections/sterilisation.

CHEMICALS COMMONLY USED FOR THIS FINISH:

•Oxidising agents such as aldehydes, halogens and proxy compounds attack the cell membrane, get into the cytoplasm and affect the enzymes of the micro organisms.

•Coagulants, primarily alcohols irreversibly denature the protein structures. Radical formers like halogens, isothiazones and peroxo compounds are highly reactive due to the presence of free electrons. These compounds virtually react with all organic structures in particular oxidising thiols in amino acids

•One of the most durable types of antimicrobial products is based on diphenyl ether (bis-phenyl) derivative known as either 2, 4, 4'-trichloro-2' hydroxy dipenyl ether or 5-chloro-2-(2, 4-dichloro phenoxyl) phenol.

LATEST PRODUCT FOR ANTI MICROBIAL FINISH:

Bio shield AM 500 which is an aqueous solution of silicon quaternary ammonium salt, the key ingredient in it being 3 - (trimethoxy silyl) - propyl - dimethyl octadecylammonium chloride

The pretreated cotton fabric is treated with bio shield AM 500 at concentrations 2% at room temperature for 30 minutes with water. The liquor ratio is 1:7. The material is hydro dried for 5 minutes. The pH is maintained at 6.

Benefits of antimicrobial textiles:-

•Uniforms, tents, defence textiles and technical textiles, such as, geo-textiles have therefore all been finished using antimicrobial agents.

•The home textiles, such as, curtains coverings, and bath mats came with antimicrobial finish.

•The application of the finish is now extended to textiles used for outdoor, healthcare sector, sports and leisure

•Bioactive fibre is a modified form of the finish, which includes chemotherapeutics in their structure, ie, synthetic drugs of bactericidal and fungicidal qualities

•The field of application of the bioactive fibresincludes sanitary materials, dressing materials, surgical threads, materials for filtration of gases and liquids, air conditioning and ventilation, constructional materials, special materials for food industry, pharmaceutical industry, footwear industry, clothing industry, automotive industry, etc.

BIBLIOGRAPHY:GOOGLEINDIAN TEXTILE JOURNEL