ANTIMICROBIAL

               FINISHES

PRACHUR BHARGAVA          

INDERPREET SINGH           

Table of contents

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Smallest organisms –biggest effects

Microorganisms are extremely adaptable. If the environment is favorable certain bacteria grow in no time from single germ to millions Germs very rapidly develop via cell division: every 20 minutes they double their population

For their growth they mainly require humidity and as a culture medium organic material is required which they attack and digest with enzymes. This is how soil bacteria and moulds are doing their invaluable job as humus producers. The same way however they destroy material of wealth for mankind. Especially good environments for the microorganisms living on the skin are areas with high humidity.

Microorganisms on textiles

Due to the close contact between skin and textiles after only a short wearing times microorganisms crowd them. Additionally their environmental conditions on textiles are similarly favorable as on the skin and thus support the microbial growth.

 Not all microorganisms are alike.

A rough subdivision can be made as:

-Bacteria

-Yeast Fungi

-Virus

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Bacteria:     Bacteria are categorized as

Gram positive

Gram negative

This classification goes back to the Danish pathologist Gram (1884) who found the test method for diversification of cellulose membranes of bacteria:

On the skin mostly Gram-positive bacteria like Staphylococci and different Coryne bacteria are found.

Gram-negative bacteria like Escheria coli are found in feces.

Microorganisms are invisible but there presence can be easily felt, smelt or even seen when they are uninhibited reproducing and then deploy their activity. They produce different degradation products which man senses as unpleasant smell growing to stench.

Bacteria e.g. convert sweat into stinking substances like carbon acid aldehyde and amines.

The proliferation of the microorganisms causes destruction of the material on which they are growing. 

Fresh and Hygienic?

It is wide spread belief that washed textiles are hygienic, fresh and clean .A study shows that this belief is partially realistic. The following test prove that this postulate:

50 test persons have been wearing for 25 days sanitized antibacterial finished wool stockings and parallel stockings without treatment were tested. Everyday the stockings have been washed at 40 C and have been worn again next day .In 5 days intervals the quantity of bacteria before and after washing have been measured. Independently of the number of washes the especially finished stockings showed always the same fresh hygienic and clean results .The not so especially finished stockings showed for a certain time after washing a reduced amount of bacteria. However after that time the number of bacteria grew explosively.

Conditions required for the growth of these organisms are:

Nutrients:

Soil, dust and some textile finishes can all be sources of nutrients for microorganism. Perspiration contains salts, amino acids, carboxylic acids and other essential nutrients. Dead skin cells or oils secreted from the skin are also a potential source of carbon. Cellulose itself is not a nutrient, but many bacteria produce extra cellular cellulose enzymes, which convert cellulose into the readily metabolized glucose.This has the dual effect of promoting further growth, and degrading the Fiber.

Water

Porous fibers of hydrophilic nature provide a suitable environment for

Growth of microorganism, Human beings have been estimated to have been estimated to give off an average of 1OOg/ hour of water as perspiration, which accumulates in clothing and bedding. A humid environment will provide enough water to support fungal growth. Bacteria need more water and require the fabric to be damp.

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Oxygen

The atmosphere provides a ready source of Oxygen.

Warmth

 Most fungi and bacteria will grow at ambient temperatures of 10-200 C. Certain bacteria prefer the slightly warmer conditions of clothing or bedding in close proximity to the skin. These bacteria such as Staphylococcus aureus, S. epidennis and Corynebacterium sp. are those most commonly found on the skin.

Affect of Microorganism growth on fabric

In the majority of cases, the presence and growth of microorganisms passes unnoticed in certain circumstances however, undesirable and possibly serious effects can occur.

Health

 The growth of certain microorganisms has been known to affect the health of the user. The consequence of infection in some case may only be a sore throat caused by Escherichia coli. S. aureus is known to infect skin, surgical wounds and burns, and can have serious effects. Textile products such as bedding, curtains, uniform and mops may be involved in the transport of bacteria within hospitals. Athlete’s foot is a common infection caused by the fungus Tricophyton mentagrophytes. The role of socks in retaining moisture and nutrients may be significant in the growth of this organism. Microorganisms may produce metabolites, which cause irritation or allergic reactions. The bactedrium Proteus mirabilis and the yeast Candida albicans are both capable of metabolizing urea to ammonia, which has been proposed as a possible cause of diaper rash. The pH increase caused by the ammonia may also irritate the skin.

Odors.

 Bacterial metabolism of perspiration in moist, warm area such as inside shoes, underarm of clothing and towels, produces the volatile molecules such as carboxylic acids and aldehydes associated with body odor. Organisms isolated from perspiration are those commonly found on the skin, such as S. aureus, S. epidennidis, Corynebacterium sp. and Propionibacteria.

Fabric Deterioration

 The cellulose enzymes produced by some bacteria and fungi are capable of degrading cotton fibers, causing loss of strength, and reducing the lifetime of the textile. Structural damage to fibers by S. aureus has been reported Fungi may also produce unsightly staining, when pigments produced diffuse into the fiber. In may case, these pigments cannot be removed by washing or bleaching.

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ANTIMICROBIAL AGENTS

Mode of Action

The mechanisms by which chemical agents exert antimicrobial activity depend upon effective contact between the chemical and the microorganism and involve disruptive interaction with a biochemical or physical component of the organisms that is essential to its structure and metabolism. The targets may be a single enzyme, a cell membrane, intercellular systems, cytoplasm, or combinations of these and the nature

 Of the action is dependent on the organisms and the environment in which the interaction occurs as well as on the antimicrobial agents

Some of the primary modes of action are as follows:

Cell wall synthesis inhibitors:

Cell wall synthesis inhibitors generally inhibit some step in the synthesis of bacterial peptidoglycan

Cell membrane inhibitors:

 They disorganize the structure or inhibit the function of bacterial membranes. The integrity of the cytoplasmic and outer membranes is vital to bacteria, and compounds that disorganize the membranes rapidly kill the cells. However, due to the similarities in phospholipids in eubacterial and eukaryotic membranes, this action is rarely specific enough to permit these compounds to be used systemically.

Protein synthesis inhibitors ~ Many therapeutically useful antibiotics owe their action to inhibition of some step in the complex process of protein synthesis. Their attack is always at one of the events occurring on the ribosome and never at the stage of amino acid activation or attachment to a particular tRNA

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Competitive Inhibitors:

 The competitive inhibitors are mostly all synthetic chemotherapeutic agents. Most are "growth factor analogs" which are structurally similar to a bacterial growth factor but which do not fulfill its metabolic function in the cell. Some are bacteriostatic and some are bactericidal.

Effects on Nucleic Acids:

 Some chemotherapeutic agents affect the synthesis of DNA or RNA, or can bind to DNA or RNA so that their messages cannot be read. Either case, of course, can block the growth of cells.

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CLASSES OF ANTIMICROBIAL AGENTS

Phenolics

Phenolics generally exhibit broad - spectrum activity against Gram-positive and Cram-negative bacteria as well as against fungi. This property plus their relatively moderate cost, make them quite cost-effective.

Phenols are considered to be moderately too highly toxic. The chlorophenols can be absorbed through the skin in toxic levels and their dusts are very irritating to the skin, eyes and respiratory tract. The formation of highly toxic chlorinated dibenzop-dioxins

As impurities in the production of various chlorophenols has been reported. However, the acceptable products given below continue td keep the phenolic class of antimicrobial agents among the most widely used in industry

Halogen compounds

 The halogens constitute a class of antimicrobial agents that are larger in commercial distribution than the phonetics. May of their applications, e.g. swimming -pool sanitizers, household and hospital disinfectants, and surgical scrubs are outside the scope of this article, but many industrial uses exist, especially for a number of organic halogen derivatives.

The halogen can be in the active or available form in which it demonstrates

antimicrobial activity because of its oxidizing capacity through a positive valence

state. The halogen also contributes activity as a covalent substituent of a complex structure. The spectrum of commercial products ranges from the elements, to inorganic hypohalites, to complex halogen -substituted organic compositions.

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Iodine Compounds.

The use of elemental iodine as antiseptic dates back to 1839 -. It is used today for various medicinal purposes.

OUATERNARY AMMONIUM COMPOUNDS (OUATS)

 The category represents one of the largest, most diverse classes of antimicrobial

agents in use. Chemically, the products may be represented by the general formula

The nitrogen atom carries four covalent bound Substituents that give it a cationic charge. The R groups may be almost any organic substituents that allow carbon nitrogen bonding with any permutation of like and unlike R groups. The nitrogen atom may be part of a heterocyclic, aromatic structure, thereby automatically fixing three substituents.

Mercurils

   Phenyl mercuric acetate (PMA) and di (phenyl mercury) dodecenylsuccinate (PMDS) are the most widely used mercury based antimicrobial agents. They act against both bacterial and fungal growth and lack color and odor besides being available at low cost. This has made them quite popular but a major disadvantage is that they are highly toxic and cause toxic effects through skin absorption, inhalation or ingestion. Hence their application is restricted to water based paints.

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Arsenicals:

These are used in diluted forms as could be toxic at high concentrations. Their major

application is in plastic industry. 10,10 - Oxybisphenoxyarsine is the only organ arsenic product of importance as an industrial antimicrobial agent.

 Organotins.

  Organotion derivatives of the R3SnX type are very active antifungal agents (where R represents alkyl and X represents a group linked to the tin through an atom other than carbon, e.g., halogen, hydroxyl, or organic radical linked through oxygen,) The most widely used Organotins antimicrobial agents are tributyltin oxide (TBTO) and tributyltin fluoride (TBTF).

 Copper Compounds.

  Copper 8- quinolinate and copper naphthenate are used in mildew proofing textiles and almost exclusively for military applications (e.g., tents, tarpaulins, and sandbags). The high concentration levels required and the intense green color makes them unsuitable for most consumer products.

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Anilides

Trichlorocarbanilide (TCC) is the only anilide that enjoy sizable sales as an antimicrobial agent; it is used almost exclusively in deodorant bar soaps. The FDA's Advisory Review Panel on over - the counter antimicrobial drug products critically reviewed appropriate data regarding the safety of salicylanilides and carbanilides, and found considerable evidence of photosensitization by halogenated salicyolanilides. The toxicology has been discussed in various articles. Subsequently the FDA placed halogenated salicylanilides in Category2 as not safe and effective for use in drug product and cosmetics.

miscellaneous compounds.

A few antimicrobial agents are unique in their functional classification. In general, each has one significant main use and, in most cases, only limited market significance as an industrial antimicrobial agent. The significant products are shown in the Table. Organic acids and their salts constitute a sizable category among antimicrobial agents.

CHOOSING AN ANTI MICROBIAL AGENT

                        The agent is chosen which:

·        Is claimed to combat the microorganism of concern to the degree desired.

·        Appears to be physically and chemically compatible with the system, i.e. will not     upset desirable physical and chemical properties of the system and (conversely) will not be inactivated by the ingredients of the system.

·        Maintains stability under use and storage conditions (pH, temperature, light, etc) for the required length of time.

·        Is safe and nontoxic in handling, formulation and use.

·        Is environmentally acceptable, and

·        Is economically acceptable and cost-effective

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APPLICATION OF CHEMICAL FINISHES

Application methods are particularly suitable:

1.Padding: Fabric is run through a pad- bath to give approximately I% of treatment fabric is then padded wet on -wet through a bath of approximately 0.5% Repulix, rinsed and dried.

Other finishes may also be applied simultaneously through slight modification of the processing conditions may be required .Due to the wide variety of finishes currently in use, compatibility should be tested on an individual basis.

2. Exhaustion: The chemical treatment exhausts rapidly from dilute aqueous solution onto cotton. Adsorption is again improved at pH 7-8 .As in the padding application; it is recommended that this treatment is followed by an acid fix and water rinse. The spraying of solutions of antimicrobial active agents is not normally recommended, due to the risk of the production and subsequent inhalation of droplets of respirable size. Nevertheless, the treatment can be applied by spraying, provide, suitable containment facilities are available; this method is particularly suitable for non-woven fabrics.

Chito-oligo saccharides as antimicrobial agents for cotton

Cotton fabric with good antimicrobial activity and durability to washing is obtained by using chito-oligosaccharides without the need for a binding chemical as a crosslinker. The fully deacetylated chitosan is depolymerized into chito-oligosaccharides using sodium nitrite. The average degree of polymerization (DP) of chito-oligosaccharides is determined by calorimetric titration of a terminal aldehyde group of chito-oligosaccharides. In a pad-dry-cure process, two different chito-oligosaccharides (DP = 3 and 10) are applied to cotton fabric using the chemical reactivity of the terminal aldehyde group. The antimicrobial activity and durability to washing of the treated cotton are evaluated. The results show that at the fiftieth wash cycle, the cotton fabrics treated with 2.4% chito-oligosaccharides are able to maintain 95% (for a DP of 3) and 100

Pre-treated cotton/polyester fabric

Cotton/polyester fabrics containing cross-linked polyethylene glycols (PEGs) show antimicrobial activity against a diverse group of bacteria and fungi. The PEG-treated fabrics have substantial resistance to most microorganisms relative to untreated fabrics. Because the level of formaldehyde is extremely low, it is hypothesized that the antimicrobial activity of the modified fabrics is due to a unique combination of physical and physicochemical effects. These may include the hydrophilic nature of the cross-linked PECs that desiccate microbes and deprive them of needed moisture and/or absorption and release of latent heat by the bound PEG. However, the most probable effects that impeded microbial growth may be attributable to the surfactant like properties of the bound PEC, which disrupt cell membranes due to the dual hydrophilic-hydrophobic characteristics of the PEGs.

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EFFECT OF ANTIMICROBIAL FINISHES ON CHEMICAL STRUCTURE

Most finishing methods directly use biocides in the finishing solutions and the biocidal; function is achieved by controlled release or consuming the biocides combined on the fabric. Therefore the imparted function will diminish as soon as the biocides vanish from the fabrics, yielding a nonregenerable finish. The traditional method has been an obstacle to achieving durable functional fabrics. In the new process, precursors of biocidal compounds were utilized instead of the biocides themselves in the treatment of cellulosic materials, and covalent bonds established between the agent and fibres before the biocidal sites are activated. The chemical structure ands of the finished fabrics and and their relationship with the properties have been explored. In this section chemical structures of MDMH treated fabrics are discussed. Structure property relationships

analyzed.

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The chemical structure can be analyzed by:

·        Identification by FITR

·        Nitrogen analysis

·        Chlorine analysis

Chemical identification by FITR: Hydantoin compounds have two prominent bends at 1720 and 1770 cm-1. Thus bends at these wavenumbers can be used as indications of the hydantoin structure grafted on to the fabric. Intensities of bend vary according to the concentration difference of MDMH in the finishing baths. The characteristics of the band are consistent with the structures of the products, providing direct evidence of the structures, and can be used to quantitavely analyze grafting rates of the chemical treatment.

Nitrogen analysis

The chemical structures of treated and chlorinated fabrics can also be characterized using elemental analysis, such as nitrogen and chlorine. Pure cotton fibres are mainly cellulose and carbohydrates, containing undectable amounts of nitrogen. Thus nitrogen contents of treated cotton fabric can be used as reference for the amount of hydantoin groups grafted into cotton fabrics.

Chlorine analysis

After chlorine bleaching, the treated fabrics will contain active chorine in the halamine form. The active chlorine bonded on nitrogen, a halamine bond, is extremely polar in the covalent bonds possessing partially positive charge. It is this chlorine that can oxidize man organic structures in proteins or in some organic compounds resulting in the inactivation of microorganisms. After the oxidation, the chlorine atom is reduced to chloride and the halamine bond reverts to a N_H bond. Because of the oxidative ability of the chlorine, its content on the fabrics can be analyzed by using the iodometric titration method .The chlorine contents on cotton and polyester/cotton fabrics treated with three different concentrations of MDMH varied after repeated washing not only relying on the concentrations of of MDMH in the finishing baths. (Graph below)

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EFFECT OF ANTIMICROBIAL FINISHES ON MECHANICAL PROPERTIES

The Biocidal properties of the fabrics are achieved by two steps of chemical processing including finishing under acidic conditions and rinse with chlorine bleach. Each of the process may have its on impact on physical properties of the fabrics. Thus whether how much the treated fabric can retain its original tensile strength at different finishing conditions is important.

Factors, which may affect the mechanical properties of the fabrics, are:

Finishing concentrations

PH value

Chlorine concentration

Drying conditions

Effect of finishing concentrations: The amount or concentration of chemicals on the materials or so-called add-on rates, will certainly affect the effectiveness of the function. A higher concentration of finishing bath help to achieve a better adds on rate on the fabrics thus improving the add-on properties. However, it also damages the tensile strength of the material more substantially than lower concentrations of finishing bath do. The graphs below show this effect on pure cotton and polyester cotton blend

               tensile strength retention of                                  tensile strength retention of                 polyester/cotton blends   treated with  MDMH              pure cotton  treated   with  MDMH

Thus polester cotton blend having 35% cotton are less vulnerable to acidic conditions and concentrations of finishing conditions

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Effect of pH values of finishing bath: The finishing of MDMH on cotton fabrics is carried out under low pH conditions. Cellulosic structures are unstable to this condition because of rapid decomposition of the chains catalyzed by the low pH. Following table shows effect on fabric with varying pH concentrations.

As pH values increase the physical properties of the fabric improve considerably.

Effect of chlorine concentrations

Chlorine solution being strongly oxidative serves as the activating and regenerating agent in treatment. Chlorine was considered very harmful to the functional moieties on the cellulose. Thus chlorine concentrations were varied to examine the influence of chlorine damage to the treated fabrics

  Based on concerns of chlorine damages to the Biocidal properties, lower concentration is preferred in both activation or regeneration process.

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ASSESSMENT OF  ANTI-MICROBIAL FINISHES

Antibacterial Test Methods.

Methods for evaluating the effectiveness of an anti-bacterial finish on fabrics have been the subject of much debate. Nevertheless, industry standard methods have been developed by bodies such as AATCC, in the US, and SEK in Japan 8.9 Example of this method are the AATCC 100 and the SEK bacterial count methods.

AATCC test Method 100: Four pieces of staked circular fabric swatches 4.8 + 0. I cm (about one gram) are inoculated with O + 0. 1 ml of inoculum in a 250 mL jar. The inoculum as a nutrient broth culute contains over I.O X 10^6 clone forming units (CFU) of organism. After the swatches are inoculated, they are neutralized by 100 ml Of a 0.2% sodium thiosulfate solution in the jar. The contact time was the interval between inoculation and neutralization. The jar is vigorously shaken and the neutralized solution is diluted in serial. The dilutions, usually 10^0,10^1, 10^2 are plated on nutrient agar and incubated for 18-24 hours at 340C. The numbers of bacteria recovered from the incubated finished fabrics are counted and compared with that of untreated fabrics.

SEK bacterial count : In this method 0.2 mi of a S. auresu suspension is inoculated onto a 2 cm square of test fabric, and incubated at 370 for 18 hours 20 min neutralizer

solution is added, and the surviving bacterial counted using a serial dilution pour plate technique. This method is considered to be the most representative of a garment or bedding exposed to perspiration and bacterial contamination. In this test, a large bacterial inoculum was used typical of that which has been found for example on socks.

 Antifungal Test Methods

The assessment of the antifungal activity of textiles is also by an agar plate method. A suspension of fungal spores is inoculated onto the surface of an agar plate, the test material placed on the agar, and further inoculum distributed over the material. The samples are then incubated, and the surface area of fabric covered with fungal

growth visually assessed. A " zone of inhibition" may be observed if the antifungal

active agent can leach from the fabric into the textile. A typical method is AATCC Test method 30.

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Assessment of durability

It is essential that the antimicrobial effect last throughout the normal lifetime of the product, which has been treated. The durability required will vary, according to the lifetime of the article, exposure and washing conditions. The tests has been based on two types of cycles:

1.Domestic wash cycle   

    Synthetic detergent      4.5g/l

    Sodiurn metasilicate    3.1g/l

    Hypochlorite bleach    1.5g/l

Wash at 45C, 15 min., rinse at 40C, and 10 min. Tumble dry at 800C, 12 MIN

2.Professional wash cycle

Synthetic detergent         4.5g/l

Hydrogen peroxide         3.1g/l

Sodium percarbonate      1.5g/l

Wash at 80C, 15 min. Rinse at 40C, IO min. Tumble-dry at 80C, 12 min. Each wash cycle considered as 5 washes in practice.

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  Anti bacterial effect after domestic washing cycle

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ANTIODOR FINISHES

It is very common to find cotton or cellulose textiles with odors, particularly if they are kept in a damp or soiled condition. For example a towel will develop a musty, mildew odor if left damp or in a humid environment such as bathroom. Clothing may develop characteristic foot or body odors .in the majority OF vases these odors are generated by the action of microorganisms such as bacteria or fungi. microbial odor generation on cotton or cellulosic textiles can e controlled by treating the textile with a finish that in=impacts a durable antimicrobial activity.

The characteristic body odor is thought to be from 3-methyl-2 hexanoic acid produced by the species of Staphylococcus epidermis and Corynrbacterium sp. Foot odor is quite different, and contains low molecular weight carboxylic acids. This may be because different microorganisms prefer the warm, moist conditions around the feet. Other odor molecules such as aldehydes and amines may also be generated .A widely studied system is the break down of urea into ammonia, by bacteria which secrete urease enzymes. This is of particular importance in babies’ diapers, where ammonia generation gives a pungent odor and also an increase indicated in nappy rash.

     Two approaches to controlling odor have been investigated, which can be considered as prevention and cure. The cure approach traps the odor molecules, which are produced preventing them from giving rise to detectable odor. The prevention approach controls the bacteria or fungi which are producing the odor molecules .A wide variety of antibacterial and antifungal active agents are known, but very few are appropriate for textile applications.

                     An investigation has been carried on poly (hexamethylene biguanide hydrochloride)(PHMB), the basis of Reputex 20, an antibacterial that does appear particularly suitable for cotton and cellulosic textile. It has been used for some tears in a variety of antibacterial applications with high human contact, such as swimming pool sanitization and preservation of personnel care products However it is recently only that applications of this molecule on textile industry have been developed.

It is a relatively safe molecule and has low mammalian toxicity. It shows good antimicrobial activity against broad spectrum of bacteria, yeasts and fungi, and has a low environmental impact since it contains no heavy metals, formaldehyde, organic halogens

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 The following tables show observations of some experiments carried out.

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SURGICAL APPLICATIONS OF ANTIMICROBIAL FINISHES

  Over the years medical personnel have worn protective clothing in the operation theater to prevent the spread of bacteria from surgical staff to patients. During surgical procedures this personnel may be exposed to sprays of blood or of other fluids that potentially contain blood-borne pathogens. Therefore surgical gowns and patient drape should have repellent properties and antimicrobial properties not only to reduce the hospital-acquired infections of patients, but also to protect the surgical staff from infectious fluids.

.                 There are two methods commonly used to reduce the spread of microorganisms. Repellent finishes are popular in consumer goods because they allow the fabric to “breathe” by allowing the passage of air through the fabric while preventing the fabric from getting wet. Although this method has shown a reduction in the transmission of microorganism, some may still be transferred through the fabric or be transmitted from one area to another. Hence the other method is to treat the fabrics with antimicrobial finishes that kill microorganisms or inhibit their growth if microorganism comes in contact with the fabric surface or if they are transmitted through the fabric. Therefore the presence of live microorganisms is reduced, resulting in reduction of microorganism transfer.

Application of chemical finishes

Chemical finishing steps involves application of chemical solution by padding, removing of water, curing the fabric after drying .The fabrics are exposed to solution containing the antimicrobial finishes using Cromax laboratory padder. The roller pressure is set to 60psi. Each fabric is padded twice to ensure even distribution of the solution.

  Triclosan-an antimicrobial finish used for surgical purposes

Triclosan is chlorine phenoxy compound that interrupts cytoplasmic membrane and interfere with the metabolic functions of cell. However it is incapable of rupturing the cell membrane of thicker blood cells, so it is safe for human and animal contact.

                               triclosan

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REFERENCES

1.             A New Durable Antimicrobial Finish For Cotton Textiles

                American Dye stuff Reporter; May 1996 (26-30)

2.            Industrial Antimicrobial Agents

               Encyclopedia Of Chemical Processing; Volt 13; 1965 ;(223-253)

3.            Durable And Regenerable Antimicrobial Finishing Of Fabrics: Biocidal 

              Properties; Textile Chemists And Colorists; Vol 30; June 1998; (26-30)

4.          A Durable Antiodor Finish For Cotton Textiles

              Textile Chemists And Colorists; Vol 28; May 1996; (28-300)

5.          Preparing Chito-Oligosaccharides As Antimicrobial Agents For Cotton Textile-                                 

             Research-Journal. 1999; 69(7): 483-488.

6.          Antimicrobial textiles; ITB International Textile Bulletin 5/2000

7.            Durable And Regenerable Antimicrobial Finishing Of Fabrics: Biocidal 

              Properties; Textile Chemists And Colorists; Vol 31: May 1999

8.          Durable And Regenerable Antimicrobial Finishing Of Fabrics: Chemical                                          

               Structure;  Textile Chemists And Colorists; Vol 30; June 1998; (31-35)

9.          Durable And Regenerable Antimicrobial Finishing Of Fabrics: Fabric                          

              Properties; Textile Chemists And Colorists; Vol 30; June 1998; (21-24)

10.        One-Bath Application of repellent and Antimicrobial Finishes to Nonwoven                                            

              Surgical Gown Fabrics.; Textile Chemists And Colorists; Vol 31: March

              1999; (11-16)

11.        New approach for imparting antibacterial activity to cellulose-containing fabrics;     

              COLOURAGE; July 1998;(13-19)

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