Bio-Finishing in Textiles

Submitted By-Disha Sahu(05)

M.F.Tech(I)

Textile finishing

• It is a process used in manufacturing of fiber, fabric or clothing. In order to impart the required functional properties to the fiber or fabric, it is customary to subject the material to different type of physical and chemical treatments.

• Textile finishing is an important step in entire textile value chain and suited for innovative process and product development-– Textile finishing accounts for about 50% of the added

value of the textile product– Implementation of innovative finishing techniques,

additives and processes largely expands the application field of textiles.

– Innovative and eco friendly techniques and additives in conformity contribute to a sustainable production and ecological products.

Application-• Textile finishing imparts functionalities to textile products that are desired

by the end user-– Colour and optimal effects– Easy care– Water/Oil repellency– Handfeel: softness, crispness– Flame-retardancy– Antistaticity– Mothproof, anti-dustmite, anti fungi..– Barrier properties against hazardous fluids and gases– Water / air (im)permeability– UV resistance– Wear resistance– Sensoring– Comfort

Research and development-

• Reduction of the environmental impact through-– Eco-friendly finishing techniques-• Application of enzymes, biopolymers and bio-

degradable auxiliaries

– Recycling and reuse of waste water– Energy friendly process by-• Process optimisation• Efficient combination of different processes.

Enzymes- Introduction

• Enzymes are proteins. Enzymes consist of long chains of amino acid, held together by peptide bonds. Some of the best known enzymes are those found in the digestive tract where pepsin, trypsin and peptidases breakdown proteins into amino acids, lipases split fats into glycerol and fatty acids, and amylases breakdown starch into simples’ sugars.

• Enzymes are basically biocatalysts. Enzymes are capable of performing these tasks, because they help to catalyze reactions. this means that by their more presence, and without being consumed in the process, enzymes can speed up chemicals process that would otherwise run very slowly, it at all.

Enzymes properties-

1. Enzymes are specific2. Enzymes are very efficient catalysts3. Origin – natural source- Enzymes are present in all

biological systems. They come from natural system and when they are degraded the amino acid of which they are made of can be readily absorber back into nature.

4. Enzymes work only on renewable raw material

Enzyme treatments of textile

Types of enzyme

Textile use and effect

Celluloses Bio-finishing, bio-polishing, anti pilling, softness, smoothness,luster improvement and stone washed effect on denim.

Amylases standard procedure for the removal of starch warps size.

Proteases In household washing agents’ better removal of proteincontaining soil or stains. Anti felting of wool, accompanied byhigh loss of weight, tear strength and the typical handle,degumming of silk with the problem of silk fibroin damage.

Lipases In detergents for the hydrolysis of lipids.

Pettiness Hydrolysis of pectins, for example in cotton preparation andretting of flex and hemp.

Types of enzymes

Textile use and effects

Catalyses Catalyse the decomposition of hydrogen peroxide, importantbefore reaction dying or printing of peroxide bleached fabricsand yarns.

Peroxidases Used as an enzymatic rinse process after reactive dying,oxidative splitting of hydrolyzed reactive dyes on the fiber andin the liquor, providing better wet fastness, decolorized wastewater and potentially toxic decomposition compound.

Ligninases Removal of burns and other plant compound from raw wool.

Collagenases Removal of residual skin parts in wool.

Esterases In development polyester finish removal of oligomers.

Esterases In development polyacrylonitrile preparation for bettercoloration.

Bio-Polishing • Neutral bio polishing gives even and better quality- Most fabrics

containing natural cotton fibers have tiny, loose or protruding yarns dotted over their surface, giving them a fuzzy texture. With repeated wearing and washing, these yarns break and their ends become tangled, resulting in pilling, which can make fairly new garments look old and worn. Bio-Polishing removes projecting fibers to improve the texture and appearance of fabrics. This not only creates a smoother fabric with resistance to pilling, but also improves softness, lustre and drape. In short, Bio-Polished fabrics look better and last longer.

• Bio-Polishing uses a group of enzymes called cellulases. These enzymes have the ability to degrade cellulose, the basic structural building block of plants and the major constituent of other cellulosic fibers.

• When the enzymes are applied to the fabric, they partially digest excess and protruding yarns, loosening them from the fabric. The resulting fuzz is then removed by high-speed mechanical agitation of the fabric, for example in a jet dyer.

Sensitive cellulases• However, this process has been hampered by the sensitivity of conventional Bio-

Polishing enzymes to pH. Most cellulases will only operate effectively across a very narrow, acidic pH range. Even very small differences in pH can alter the performance and effect of the enzymes.

• All this means that manufacturers must take great care to ensure that the solution is at the correct pH for the enzyme to work properly and that the pH is uniform throughout the solution. The processes taking place before Bio-Polishing, for example bleaching and dyeing, require a high, alkaline pH. Operators must therefore carefully adjust the pH of the solution by adding acid prior to Bio-Polishing.

• The time taken to adjust the pH and wait for even circulation can significantly draw out the Bio-Polishing process.

• Seemingly trivial differences in pH between batches can lead to variability in the finish of the end product. Worse still, the acidic pH needed for optimum enzyme performance can reduce the dye retention of the fabric, resulting in colour fading

A new generation of Bio-Polishing• Novozymes’ latest product, Cellusoft CR, is an

easy-to-use, fast-acting cellulase specially developed to improve Bio-Polishing in the textile industry.

Cellusoft CR advantages over conventional cellulases used in Bio-Polishing

• It allows Bio-Polishing under neutral conditions. • It operates across a much wider pH range than the conventional

cellulases used in Bio-Polishing, eliminating the need to adjust the pH of the solution after dyeing or bleaching, reducing the total time needed for the Bio-Polishing process.

• As the enzyme can operate optimally over a wider pH range, small differences in pH do not affect the finish of the final product., Cellusoft CR ensures consistency of the end product with each and every batch.

• Excellent colour retention properties when used on dyed fabrics.• It minimises fabric weight loss in Bio-Polishing. And it produces a

visibly smoother fabric with lower lint formation and higher tensile strength.

Cost-effective quality in no time

• Bio-Polishing has the potential to give textile manufacturers a clear edge over their competitors. But up to now many have avoided Bio-Polishing altogether because of poor repeatability and the time needed to complete the process. Others only consider using Bio-Polishing as a remedial measure for fabrics in which pilling is identified as a problem. With Cellusoft CR, Novozymes offers textile manufacturers a reliable, cost-effective Bio-Polishing solution.

• With its broad pH range (pH 5-8), Cellusoft CR can be easily incorporated into standard protocols to improve the quality of a multitude of fabrics. And what is more, it can be used in combination with other enzymatic processesused in fabric finishing, for example Bio-Scouring, Bleach Clean-Up and desizing.

• “Cellusoft CR is ideal for all textile manufacturers, whether they are currently using Bio-Polishing or not,” says Han Kuilderd.

• “Besides the readily visible effects on fabric quality, the broad pH profile of Cellusoft CR will help manufacturers to reduce acid consumption, processing times and batch failures. And this ultimately adds up to cost-savings.”

• Bio-Polishing at neutral and near neutral pH helps to prevent colour loss in dyed fabrics compared to conventional acid cellulases.

Various enzymes playing role in finishing-Enzyme Description

TEXYME DGS Special proteolytic enzyme for degumming of silk

TEX BIOSCOUR Multicomponent scour formulation for scouring cotton fabric

TEXZYME BPL Fungal acid cellulase for premium bio-polishing

TEXAMYLASE/ TEXAMYLASE Liquid Desizing enzyme based on conventional bacterial alpha amylase

TEXZYME AC Fungal acid cellulase for bio washing of denim material

TEXZYME NC Fungal neutral cellulase for premium bio-abrasion

TEXZYME PK Catalyses decomposition of residual hydrogen per oxide to oxygen and water. The product is highly specific for hydrogen peroxide and will not react with dyestuffs.

Physical properties of naturally coloured cotton khadi fabric

treated with enzymatic finish

Mechanical properties-

1.1 Yarn Count (Ne)

• There is an increase in the yarn count of the enzyme treated samples compared to control because of warp yarns being relatively coarser have larger surface area with little protruding fibres which were removed during the enzyme treatment and probably make the yarns fine and smooth.

1.2 Cloth count (Numerical expression)

• There is an increase in cloth count with increase in treatment time. On enzymatic treatment the yarns became finer and the wet treatments resulted into weave compactness, thus enhancing the number of threads per unit area. The statistical results revealed that enzymatic treatment positively influenced the cloth count.

1.3 Mass per unit area (g)

• Weight per square meter of the finished fabric decreased with enzymatic treatment. Loss in cloth weight increased with increase in treatment time. Greater weight loss with increased treatment time is due to the removal of more surface fibers or fuzz present on the fabric along with size, during mechanical agitation of enzyme treatment.

1.4 Cloth thickness (mm)

• Enzymatic treatment decreased the thickness of the test samples, which increased with increase in treatment time. The change is mainly due to enzymatic hydrolysis of cellulose especially in the amorphous region. This hydrolysis removes the protruding fibers covering the fabric surface, thus reducing the thickness of enzyme treated test samples.

1.5 Cloth bending length (cm)

• The bending length is a characteristic property of a fabric and is dependent upon the energy required to produce a given bending deformation under its own weight.

• Bending length of the control sample is greater both in warp and weft ways, however warp-way bending path was longer than weft-way at control but a trend of decrease is noticed on enzymatic treatment. This may be due to softness and smoothness, which made the fabric more pliable. This in turn reduced bending path on enzymatic treatment.

1.6 Cloth crease recovery angle (degree)

• Samples treated with enzyme at different treatment times shows gradual decrease in crease recovery angles in both warp and weft directions. This may be because of the effect of enzyme that imparted softness in the colour linted cotton by hydrolyzing and removing the surface fibres.

• These values are supported by the values of reduction in bending path, which in turn reduced the crease recovery property i.e. lower the bending path, softer the fabric and lesser the crease recovery angle. From this it is evident that the fabric is made more pliable and flexible on application of enzyme finish.

1.7 Cloth dimensional stability (%)

• The warp-way shrinkage of control was found to be greater than weft at control may be because of desizing and relaxation of yarns that lead to shrinkage.

• On the other hand enzyme finished samples showed slight shrinkage both in warp and weft way as these samples have already under gone wet treatment during enzymatic finish hence, there was not much change in the dimension when tested for shrinkage. Moreover treatment time did not adversely affect the dimensions of the enzyme treated samples, which is a positive result.

2. Functional properties

2.1 Cloth elongation (%)

• There is reduction in elongation (%) when treated with enzymes. This fall in the percentage value may be because of hydrolysis of cellulose and removal of protruding surface fibers. Further, increase in treatment time, progressively decreased the cloth elongation per cent.

• This may be because at the initial stage hydrolysis of cellulose involved removal of surface fibers and in the later stages the enzyme probably attacked the amorphous region of the cellulose resulting into further reduction in cloth elongation.

2.2 Cloth tensile strength (kgf)

• Enzyme treated samples showed decrease in tensile strength. Enzyme treatment decreased the cloth elongation, which is directly proportional to tensile strength. Further, it is also evident that decrease in warp-way tensile strength was greater in treated sample for treatment time of 30 minutes and 60 minutes, because warp yarns are coarser than weft and in principle, coarser yarns have greater surface area with more hairiness for enzyme hydrolysis, which resulted into greater strength loss in tensile strength.

2.3 Cloth tear strength (g)

• The warp way tear strength of the test samples is higher than their corresponding weft way, may be because weft yarns were finer than the warp. In principle denser fabrics have lower tear strength and it holds good.

• Enzyme treated samples did show a trend of decrease in tear strength both in warp and weft directions. This may probably because, during enzyme treatment not only the surface hairiness was reduced but also there was progressive consolidation of yarns on wet treatment that in turn enhanced the cloth count. It is true that higher the cloth count lower is the tear strength.

2.4 Cloth abrasion resistance (Cycles)

• Failure of abrasion resistance is mainly due to weakening of the structure caused by mechanical breakdown of individual fibers and which is substantially the same for all fibers. Only those fibers held firmly by tension and pressure sustain intensive abrasive action. The physical properties influencing the cloth abrasion resistance to a greater extent are yarn count and thickness and to some extent the sizing material that is held mechanically on the cloth surface.

• Among the test samples,control showed greater resistance to abrasion. This may be due to the presence of size that formed a thin film on the surface, in turn added to the cloth thickness thus resulting into better abrasion resistance, where as enzyme treated naturally colored cotton samples exhibited relatively low resistance to abrasion may be because of removal of size during wet treatment, hydrolysis of cellulose, breaking of fibers on mechanical agitation during finishing process, where in the yarns became more finer, pliable, thus was loss in thickness.

2.5 Cloth drapability (%)

• Enzymatic finish improved the drapability of naturally coloured linted cotton samples. Because enzyme treatment improved the softness of the khadi samples which is evident from decrease in bending length and increase in crease recovery angle.

• This softness improved the drapability of the enzyme treated samples when compared to control, which was stiffer with longer bending path because of presence of sizing material that showed relatively poor drapability.

2.6 Cloth pilling (Ratings)

• Pilling is a fabric surface fault characterizes by little ‘pills’ of entangled fiber clinging close to the cloth surface. Under the influence of rubbing action loose and small fibers develop into small spherical bundles anchored to the fabric by a few unbroken fibers. It is clear that enzyme finished samples showed excellent resistance to pilling.

• This may be because of the small fibers and fuzz present on the control fabric, which were removed during enzyme treatment resulting into a fabric with non fuzzy surface, where as control khadi sample showed moderate pilling because of fuzziness on the cloth surface.

Effect of enzymatic finish on physical properties of naturally coloured cotton

khadi fabric• Enzymatic treatment increased the yarn count and cloth count of the naturally

colour linted cotton khadi fabric compared to control.• There was decrease in thickness of the test samples on enzyme treatment.• Decrease in cloth bending length and crease recovery was noticed in enzyme

treated fabric samples.• Colour linted cotton khadi samples attained dimensional stability after enzyme

treatment.• Enzyme treated test sample showed decrease in tear strength. There existed a

negative relation slip between cloth count and tear strength.• Resistance to abrasion decreased on enzyme treatment in terms of per cent

increase in loss of thickness and mass/unit area.• Cloth thickness is directly proportional to abrasion resistance.• Enzyme treated samples showed better drapability compared to control and

naturally colour linted fabric samples with enzymatic finish showed excellent resistance to pilling.

References-• BOOTH, J.E., 1983, Principles of Textile Testing, Edn. 6., CBS Publishers and

Distributors, New Delhi. Pp: 267-300.• CHARYULU, N.R., 1996, Naturally coloured Asiatic cottons of India. Journal

of Indian Society for Cotton Improvement, 21:173-176. CHATTOPADHYAYA, D.P., CHATTARJEE, K.N., BHANDRA, I. AND RUCEERE GEMBER, 1997, Studies on enzymatic fading. Man-made Textiles in India, 40(1): 452-454..

• GULRAJANI M. L., AMIT DAYAL AND CHAKRABORTY, Kawabata evaluation of enzyme-treated cotton knitted fabric. Indian Journal of Fibre and Textile Research, 22: 211-221.

• GULRAJANI M.L., PAROMITA ROY, RITU AGARWAL AND SUBHAS CHAND, Enzymatic treatment of cotton knits. Indian Journal of Fibre and Textile Research, 23:242-249.

• JHA, V., 2005, The end of Quota Era. Yojana, 49:4-5.KATHIRVELU, S.S., 2002, Enzymatic preparatory processes. Textile Trends, 45 (9): 33-36.

• Biopolishing of jute cotton union fabric. Indian Journal of Fibre and Textile Research,21: 127-130.

• SINHA, S.K, 1998, Naturally hued cotton-it is not new for khadi. Proceedings of Workshop on Eco-friendly Cotton, pp: 45-47.SUMAN AND KHAMBRA, K.

• Effect of enzyme treatment on physical properties of denim. Synthetic Fibres, 32 (4): 23-26.

• THILAGAVATHI, G., RAJENDRA, K. AND JEEVAREKHA, T., 2005, Biosoftening to improve hand values of cellulosic. The Indian Textile Journal, 115 (4): 38-39.

• VERMA N., 2002, Enzymes in textile wet processing. Textile Trends, 45(5): 27-30.

• Website: http://www.foxfibre.com/cotton/nicci.html.• Website: http://www.nodyes@foxfibre.com.