SELFCLEANINGGARMENTS

BY,

S.PARTHIBAN

PSGCOLLEGEOFTECHNOLOGY

ABSTRACT

Water and soil repellency has been one of the major targets for fiber and textile scientists and

manufacturers for centuries. Nano science is employed for this type of problems. From the nano

science self cleaning is the wonderful technology for dirt free with other functional finishes. So,

through this paper we deals with various mechanisms of self-cleaning and the coatings,

manufacturing methods, and also various functional finishes like antimicrobial; UV ray finishes

which can be imparted with the major advantages than the other conventional finishes and

application area of this technique. Connection to this limitation, problems with this technique

and recommendations for the purpose of bringing out new ideas which is incorporated in the self

cleaning garments.

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CONTENTS INTRODUCTION...4

NANO LIFT UP THE SELF CLEANING FINISHES....4

SELF-CLEANING MECHANISM...4

MANUFACTURING METHOD...5

1. HYDROPHOBICCOATINGSTHELOTUS-EFFECT...5 2. HYDROPHILIC PHOTO CATALYTIC COATINGS....6 3. USING SILVER NANOPARTICLES...7 4. EASY TO CLEAN FINISHES...8

OTHER FUCTIONAL FINISHES...9

1. ANTIMICROBIAL FINISH....9 2. UV PROTECTIVE FINISH..10

INNOVATION IN SELF CLEANING FINISHES.....11

1. SELF-CLEANING WOOL AND SILK....11 2. PHOTO CATALYTIC DEGRADATION OF ODORS COMPOUND.....12

CHARACTERISTICS OF SELF CLEANING GARMENTS...12

FUTURE WITH SELF-CLEANING GARMENTS ...13

AREAS OF APPLICATION..13

PROBLEMS WITH SELF-CLEANING FABRICS....14

RECOMMENDATION...14

CONCLUSION.14

REFERENCES.14

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INTRODUCTION:

Nature has already developed an elegant approach that combines chemistry and physics to create

super repellant surfaces as well as self cleaning surfaces. Lotus leaves is the best example of

self cleaning surfaces. The technology of self-cleaning coatings has developed rapidly in recent

years. As a commercial product, their potential is huge and their market truly global. Because of

the wide range of possible applications. The concept of self cleaning textiles is based on the lotus

plant whose leaves are well-known for their ability to self-clean by repelling water and dirt.

Now days peoples are very busy in their work that they do not have time for clean their daily

wear cloths also people who are working in kitchens having headache to wash their garments.

Also military peoples have to survive in such drastic condition that they cannot wash their cloths.

Nano technology provides a new concept self cleaning textiles which gives self cleaning as well

as fresh cloths every day, this not only technically benefited but techno economically also

benefited. The field of self-cleaning coatings is divided into two categories: hydrophobic and

hydrophilic. These two types of coating both clean themselves through the action of water, the

former by rolling droplets and the latter by sheeting water that carries away dirt. Hydrophilic

coatings, however, have an additional property: they can chemically break down adsorbed dirt in

sunlight.

NANO IS BASICS FOR SELF CLEANING GARMENTS:

Nanotechnology is regarded as a key technology, which will not only influence technological

development in the near future, but will also have economic, social and ecological implications.

Nanotechnology deals with the science and technology at dimensions of roughly 1 to 100

nanometers (1 Billion Nanometers = 1 Meter), although 100 nanometers presently is the

practically attainable dimension for textile products and applications. Conventional methods used

to impart different properties to Fabrics often do not lead to permanent effects, and will lose their

functions after Laundering or wearing. Nanotechnology can provide high durability for fabrics,

because nano-particles have a large surface area-to-volume ratio and high surface energy.

SELF-CLEANING MECHANISM:

Nanocare fabrics are created by modifying the cylindrical structure of the cotton fibres making

the fabric. At the nanoscale, cotton fibres like tree trunks. Using nanotechniques, these tree

trunks are covered in a fuzz of minute whiskers which creates a cushion of air around the fibre.

When water hits the fabric, it beads on the points of the whiskers, the beads compress the air in

the cavities between the whiskers creating extra buoyancy. In technical terms, the fabric has been

rendered super-non wettable or super-hydrophobic.

The whiskers also create fewer points of contact for dirt. When water is applied to soiled fabric,

the droplet on an inclined super hydrophobic surface does not slide off; it rolls off. When the

droplet rolls over a contamination, the particle is removed from the surface if the force of

absorption of the particle is higher than the static friction force between the particle and the

surface. Usually the force needed to remove a particle is very low due to the minimized contact

area between the particle and the surface. As a result, the droplet cleans the leaf by rolling off the

surface.

Diagram showing a droplet cleaning a super hydrophobic surface by rolling off

Due to their high surface tension water droplets tend to minimize their surface trying to achieve a

spherical shape. On contact with a surface, adhesion forces result in wetting of the surface: either

complete or incomplete wetting may occur depending on the structure of the surface and the

fluid tension of the droplet. The cause of self-cleaning properties is the hydrophobic water-4

repellent double structure of the surface. This enables the contact area and the adhesion force

between surface and droplet to be significantly reduced resulting in a self-cleaning process.

MANUFACTURING METHOD:

The manufacturing of self-cleaning textiles using nanotechnology:-

Using hydrophobic coatingsthe lotus-effect

Using hydrophilic photo catalytic coatings

Using silver nanoparticles

Using easy to clean finishing

1. HYDROPHOBICCOATINGSTHELOTUS-EFFECT:

THE PHYSICAL BASIS:

Forces acting on a liquid droplet on a solid surface

To understand the physics behind the Lotus-Effect, the roughness of a surface improves the wet

ability for hydrophilic surfaces Y (< 90). The drop will seem to sink into the hydrophilic surface. The Y wet ability decreases for hydrophobic surfaces (> 90). It gets energetically too expensive to wet a rough hydrophobic surface. The result is an increased water-repellency.

A droplet on a hydrophilic rough surface seems to sink into the gaps

A droplet on a rough hydrophobic surface sitting on the spikes

Theory as to how this hysteresis varies with the chemical and topological properties of the

surface is still being developed, but ideally hysteresis should be as close as possible to zero if

drops are to roll easily, at low surface inclination angles. Because droplets tend to roll only on

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surfaces with very high static contact angles, the requirements for a self-cleaning hydrophobic

surface, therefore, are a very high static water contact angle, (< 90) , and a very low roll-off angle, i.e. the minimum inclination angle necessary for a droplet to roll off the surface. If the

wetted surface is more energetically favorable than the dry surface, the static contact angle will

be less than 90 and the surface is termed hydrophilic. If the dry surface is more favorable, then

the surface is hydrophobic, and its static contact angle will be greater than 90.

2. HYDROPHILIC PHOTO CATALYTIC COATINGS:

These hydrophilic photo catalytic coatings chemically break down dirt when exposed to light, a

process known as photo catalysis, although of course it is the coating not the incident light that

acts as a catalyst.

TITANIUM DIOXIDE: THE ACTIVE PHOTOCATALYST:

TiO2 has been proved to be an excellent catalyst in the photo degradation of colorants and other

organic pollutants. The fabric is coated with a thin layer of titanium dioxide particles heaving 20

nanometers diameter. Titanium dioxide is a photo catalyst; when it is illuminated by light of

energy higher than its band gap, electrons in TiO2 will jump from the valence band to the

conduction band, and the electron (e) and electric hole (h+) pairs will form on the surface of the

photo catalyst. The negative electrons and oxygen will combine to form O2 , radical ions,

whereas the positive electric holes and water will generate hydroxyl radicals OH. Since both

products are unstable chemical entities, when the organic compound i.e. dirt, pollutants, and

micro organisms falls on the surface of the photo catalyst it will combine with O2 - and OH- and

turn into carbon dioxide (CO2) and water (H2O).Since the titanium dioxide acts as a catalyst, so

it is never used up.

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This coating will react through two distinct properties: photo catalysis causes the coating to

chemically break down organic dirt adsorbed onto the fabric, while hydrophilicity causes water

to form sheets rather than droplets contact angles are reduced to very low values in sunlight

(the coating becomes super-hydrophilic), and dirt is washed away. Super-hydrophilic state, it is

also non-toxic, chemically inert in the absence of light, inexpensive, relatively easy to handle and

deposit into thin films Metallic gold or platinum nanoparticles can assist photo-catalysis in TiO2

by acting as charge separators.

This finish also have anti bacterial properties after having been subject to 55 washes through

home laundry machine & UV protection characteristics for 20 washes.

OTHER MATERIALS:

Several metal oxides and sulfides, including WO3, ZrO2, ZnO and CdS, and polyoxometallates.

3. USING SILVER NANOPARTICLES:

A highly water-repellant coating made of silver nanoparticles that can be used to produce suits

and other clothing items that offer superior resistance to dirt as well as water and require much

less cleaning than conventional fabrics. Nano-Tex improves the water-repellent property of

fabrics by creating nanowhiskers, which are made of hydrocarbons and have about 1/1000 of the

size of a typical cotton fiber. They are added to the fabric to create a peach fuzz effect without

lowering the strength of cotton.

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While treated textile surface do not adheres the dust particles hence when water particles rolls

over it dust get washed off.

4. EASY TO CLEAN FINISHES:

ETC-Easy to clean surfaces was water repellent accordingly are often confused with other self-

cleaning functions such as LOTUS EFFECT. Unlike the latter, easy- to- clean surfaces are

smooth rather than rough. Surfaces have a lower force of surface attraction due to a decrease in

their surface energy, resulting in reduced surface adhesion. This causes water to be repelled,

forming water droplets and running off. Easy-to-clean surfaces are therefore hydrophobic i.e.

water-repellent and often also oleo phobic i.e. oil repellent, making them suitable for use in

bathroom.

MECHANISM:

The primary difference here is that easy to clean surface coatings do not require uv light to function and their hydrophobic surface properties-as opposed to hydrophilic-cause water to run of in droplets rather than forming a thin film of water. Water that runs off inclined ETC surfaces forms droplets, washing away surface grime in the process.

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ADVANTAGES:

Generally speaking easy to clean surfaces are less susceptible to dirt accumulation.

The benefit: stress free and easy cleaning, saves time and cost

LIMITATIONS:

The disadvantage is that droplets dry individually, leaving behind dirt residues although

these are easy to remove.

When only a small amount of water is involved, droplets of run off water can form

runaways.

It is therefore necessary to consider where and how the easy-to-clean function should best

be employed.

As a rule, suitable surfaces should be inclined and exposed to sufficient quantities of water.

Abrasive detergents and brute force application by cleaning personnel-in the worst case

both together and not uncommon and with time will damage

OTHER FUCTIONAL FINISHES:

ANTIMICROBIAL FINISH: Silver ions have broad spectrum of anti microbial activities. Prof. Yang has patented a process

for preparing a silver nano particle containing functional microcapsule having the intrinsic anti-

microbial and therapeutic functions of silver as well as additional functions of the products

contained in the inner core of the capsule.

These microcapsules can be prepared by a two step process.

1. In the first step an emulsified solution of a perfume is encapsulated with melanin pre-

condensate.

2. In 2nd step microcapsule so produce is treated with silver nano particle dispersed in water

soluble styrene maleic anhydride polymer solution before it fully dies. Thus the

microcapsules with duel function are produced.

In these microcapsules, the silver nanoparticles are on the surface of the capsule. Instead of

perfume, we may use thermo sensitive pigment, thermal storage materials or pharmaceutical

preparation in the inner core. The method of producing durable silver containing antimicrobial

finish is to encapsulate silver compound or nano particle with a fibre reactive polymer like poly

(styrene co-maleic anhydride).

The treated yarns showed effective anti-microbial activity against various bacteria, fungi and

Chlamydia that included escherichia coli, citrobacter, and bacillus subtilis. These finished goods

are used in medical industry as a safe & effective means of controlling medical growth in the

wound bed.

UV PROTECTIVE FINISH:

The most important functions performed by the garment are to protect the wearer from the

weather. However it is also to protect the wearer from harmful rays of the sun. The UV-blocking

property of a fabric is enhanced when a dye, pigment, delustrant, or ultraviolet absorber finish is

present that absorbs ultraviolet radiation and blocks its transmission through a fabric to the skin

Metal oxides like ZnO as UV-blocker are more stable when compared to organic UV-blocking 10

agents. Hence, nano ZnO will really enhance the UV-blocking property due to their increase surface

area and intense absorption in the UV region. For antibacterial finishing, ZnO nanoparticles scores

over nano-silver in cost-effectiveness, whiteness, and UV-blocking property.

INNOVATION IN SELF CLEANING FINISHES

SELF-CLEANING WOOL AND SILK:

Soon garments made of wool and silk may need no dry cleaning or other special treatment in

order to remove marks and stains just expose them to sunlight. It is all due to a nano particle

coating. For that, nano titanium dioxide that are four to five nanometers in size. These fibers are

made of a protein called keratin, which does not have any reactive chemical groups on its surface

to bind with titanium dioxide. So it is more difficult to process. The researches chemically

modify the surface of wool fibers, adding chemical groups called carboxylic groups, which

strongly attract titanium dioxide. Then they dip the fibers in a titanium dioxide nanocrystal

solution. Titanium-dioxide-coated wool shows almost no sign of the red stain after 20 hours of

exposure to simulated sunlight. Other stains disappear faster: coffee stains fade away in two

hours, while blue-ink stains disappear in seventeen hours.

PHOTO CATALYTIC DEGRADATION OF ODORS COMPOUND:

A photo catalytic acrylic fiber SELFCLEAR yarn with higher-dimensional self-cleaning

properties which had been exclusive with conventional photo catalytic fibers, and started

recently sailing their product for manufacture of clothing, sportswear, uniforms, bedding,

carpets, and daily goods. Because titanium oxide is applied into SELFCLEAR yarn, it has a

higher self-cleaning activity with deodorant, antibiotic, and anti-soiling properties as well as

excellent functional stability, as compared to fabrics using a conventional photo catalytic

reaction.

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CHARACTERISTICS OF SELF CLEANING GARMENTS:

1. Another plus is that they can be permanently attached to the garments fibers without

altering its texture or feel.

2. The self-cleaning clothes can also help conserve a considerable amount of water and

energy that is normally utilized during the cleaning process.

3. Self-cleaning property will become a standard feature of future textiles and other

commonly used materials to maintain hygiene and prevent the spread of pathogenic

infection.

4. The lotus leaf nanostructure and nano titanium dioxide coating built on fabric can defend

and decompose stains, dirt, odours, bacteria, harmful gases, and highly water and oil

repellent.

5. Self-cleaning garment can effectively reduce the laundering process so as to protect the

environment.

6. The self-cleaning garment also possesses excellent UV protection property. The

treatment has excellent durability towards washing and normal usage without sacrifices

the soft hand and breathability of textile fabrics.

7. A polymer film mixed with silver nanoparticles -- can be permanently integrated into any

common fabric, including silk, polyester and cotton.

8. In the long run, it can save time and money by reducing expensive dry cleaning bills. It is

also environmentally friendly

9. Saving time and laundering cost.

10. This technology embraces environmental friendly properties.

11. The crease resistant feature keeps clothing neat.

12. Garments stay bright, fresh looking and are more durable than ordinary materials.

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The economic significance of the self cleaning textiles can be outlined as follows:

1. Ease of maintenance and environmental protection because of reduced cleaning efforts

2. Time, material, energy reduction and consequently cost-efficiency during production

3. Makes textiles longer-lasting

4. People need not to suffer from heavy laundry bills.

5. Improved ageing behavior by extended surface purity effect.

FUTURE WITH SELF-CLEANING GARMENTS:

The ultimate consequence in developing these self-cleaning fabrics is that we can really limit our

use of things like chemicals, energy and water. That offer superior resistance to dirt as well as

water and require much less cleaning than conventional fabrics. Currently, industrial testing and

mill trials of this patent-pending technology are being conducted. It is anticipated that as soon as

the technology receives the approval technically and economically, self-cleaning property will

become a standard feature of future textile and other commonly used materials to maintain

hygiene and prevent the spreading of pathogenic infection. The coating could be applied to suits,

hospital garments, sportswear, military uniforms and outdoor fabrics. It could appear in

consumer products within five years.

AREAS OF APPLICATION:

Medical textiles e.g. Hospital garments Sport tech e.g. Athletic wear Defense textile e.g. Military uniforms Smart textiles Upholstery under garments

PROBLEMS WITH SELF-CLEANING FABRIC:

The main reasons that self-cleaning fabrics require a lot of time to break down stains is because

Titanium dioxide is very inefficient at using energy from sunlight. Excitation of electrons to the

conduction band is only the beginning of the cleaning process. These electrons must then react

with oxygen atoms, which then react with the dirt particles. All of these reactions are limited by

access to and the amount of freed electrons in the titanium dioxide. So for a large stain, a lot of

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light energy is needed before the fabric can fully break it down. And also batch processing of a

hydrophobic material is a costly and time consuming technique.

RECOMENDATION:

Super hydrophobic materials, which repel water, are typically good at removing dirt particles but

don't deal with oils well. Materials that repel oil might not work with certain types of oil. The

titanium-dioxide-coated materials, on the other hand, will not work unless they are exposed to

sunlight for hours. Prices of clothing and other products treated with the new coating will

initially be a bit more expensive than other water-repellant garments; researches are currently

working on ways to make the coating cheaper. Further research would be required to test ways of

applying titanium dioxide nanofilms to other textiles.

CONCLUSION:

The realization of self-cleaning properties on textile surfaces by using the nanotechnology

includes a vast potential for the development of new materials or new products and applications

for known materials. The opening of new application fields for textiles will lead to a new growth

stage. For the growing market of technical textiles a further increase in production volume, sales

and application fields can be expected by successful transfer of the self cleaning effect on textile

materials. Structure based soil and water-repellent properties lead to an efficient use of materials

and are therefore in agreement with the principles of sustainable development. The use of a self-

cleaning coating is attractive as they are labor saving and effectively improve the appearance of

the environment. In the long run, it can save time and money by reducing expensive dry cleaning

bills. It could take about five years for the retail market for self-cleaning clothes and linens to

launch as the technology still needs refining.

REFERRENCES:

www.fibre2fashion.com\technical textile\self cleaning finishing www.proquest.com\selfcleaningofcotton http://textileinfo.com/en/tech/nanotex www.textileinfo.com www.iir-germany.com/nanotrends/ http://www.lotusan.de/ (in German). http://www.activglass.com/index_eng.htm. http://www.ppg.com/. A. Marmur, Langmuir, 2004, 20, 3517.

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W. Extrand, Langmuir, 2002, 18, 7991. Neinhaus and W. Barthlott, An. Bot., 1997, 79, 667. Eur. Pat., EP 0772514, 1998. S. R. Coulson, I. Woodward, J. P. S. Badyal, S. A. Brewer and C. Willis, J. Phys. Chem. B, 2000, 104, 8836. A. B. D. Cassie and S. Baxter, Trans. Faraday Soc., 1944, 40, 546. J. Bico, C. Marzolin and D. Quere, Europhys. Lett., 1999, 47, 220. S. Shibuichi, T. Onda, N. Satoh and K. Tsujii, J. Phys. Chem.