Textile Finishing - MyCourses

Textile Finishing @ Aalto University October 11, 2021

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Antimicrobial fabric

• Ali Tehrani

TextileFinishing

Email: [email protected]

Ali Tehrani

A!Aalto University

School of ChemicalEngineering

Chapter 1

https://www.sciencedirect.com/book/9780081006467/principles-of-textile-finishing

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Final Finishing

Textile Finishing included preparatory processes + Final Finishing after dyeing

Textile Chemistry

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Dyeing Finishing

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Definitions

• Textile Coloration: Adsorption of dyes (natural or synthetic organic molecules) onto textile materials (e.g., fibers, yarn, or fabric).

• Textile Printing: adding colorful patterns and designs on fabrics by applying printing paste containing colorants, thickener, emulsifier, water, oil, and binder

• Textile Finishing: A wide range of mechanical and chemicalprocesses to render desired qualities on textile materials (mostly in fabric form)

Objective of Final Finishing

• to improve the attractiveness, function, and/or serviceability of fabrics.

Know How ?

Important parameters?

Machines?

Chemicals?Trade secrets?

Cost?

Fashion? Environmental Impact?

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Important Parameters

The variations of finishing depend on the following factors:

• Type of fiber and their physical-chemical properties

• Type of fabric and design

• The behavior of textile materials to various finishing processes

Textile Textile Finishing

Purpose Durability Method

Aesthetic

Functional

Temporary

Semi-permanent

Permanent

Mechanical

Chemical

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Finishes

• Handle (Softness / Stiffness)• Lustre • Fulling / Compacting• Napping, Brushing, Sueding• Shearing

Aesthetic

Fabric Luster

• Luster may be imparted to a fabric by physical means. The techniques basically involve flattening or smoothing the surface yarns using pressure.

Luster is a measure of light reflectance from the surface.Gloss: Surface luster

Silk Fabrics Vs. Cotton Fabrics

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Example: Compaction of woolen fabrics

• Compaction or Fulling is the process of beating woven woolen fabric while wet to cause the opposing fibers to interlock and form a more homogenous textile.

Unfulled fabric Fulled fabric

What is the mechanism?

Compacting / Fulling

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Compaction of woolen fabrics

• The scale structures on protein fibers entangle and stick on agitation, particularly in the presence of moisture. The resulting ‘ratcheting’ effect causes the fibers to compact and felt.

Mechanical vs. ChemicalFinishing

Mechanical Finishing Chemical FinishingDry Process Often wet by the addition of chemicals

Dry chemical finishing?

Mainly physical Mainly chemical with mechanical assistantExamples: heat setting, calendering, emerising, compressive shrinkage, raising, brushing and shearing or cropping

Examples: antimicrobial, fire retardance, waterproof, …

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Question?

• Chemical finishing is impossible without mechanical assistance, such as fabric transport and product application. What is the major distinction?

the major distinction between the two is what caused the desired fabric change, the chemical or the machine?

Textile Finishing?No Properties Yes

Interlacing yarns

Coloring fabrics with natural dyes

Enforcing sewing yarns by silicon treatment

Enhancing the appearance of a fabric by ironing

Washing fabric

Bleaching fabric

Yarn spinning

Heat pressing nonwovens

Objective of finishing :to improve the attractiveness and/or serviceability of yarn/fabric.

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Finishing Durability

Temporary PermanentMechanical: calender, embossing, glazing, breaking, stretching, etc.

Mechanical: compressive shrinkage, milling of wool, raising and cutting processes, permanentsetting, etc.

Filling: starch, china clay and other mineral fillers Deposition: synthetic resins—both internal and external, rubber latex, laminating, etc.

Chemical: adding oil, different softeners and other finishing agents.

Chemical: mercerization, cross-linking agents, water repellent finish, fire-resistant and fireproofing finishes, shrinkproofing of wool, etc.

Discussion

• What are your important parameters for choosing a new dress?

Discussion on Presemo !

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Functional Finishes

Wrinkle resistance

Flame retardency

Absorbency

Soil release

Water repellency

Resistance to micro-organism

Resistance to insect

Resistance to static charge

Resistance to pilling

Abrasion and wear resistance

Thermal conductivity

Resistance to heat, UV light and pollutant

Wet Chemical Processes

Functional Finishes1. Wrinkle resistance or resiliency—for cellulosic fibres and their blends with synthetics2. Flame retardancy—for most natural and synthetic fibres3. Absorbency—usually to impart hydrophilicity to synthetic fibres4. Soil release—primarily for synthetic fibres and their blends5. Repellency (soil and stain)—primarily for synthetic fibres6. Repellency (water)—primarily for cellulosic fibres7. Resistance to microorganisms—primarily for cellulosic fibres, all fibres for medicalpurposes8. Resistance to insects—mostly for wool fibres9. Shrinkproofing—primarily for cellulosic and wool fibres10. Resistance to static charges—primarily for synthetic fibres11. Resistance to pilling—high tenacity synthetic fibres and their blends12. Abrasion and wear resistance—primarily for cellulosic fibres and their blends13. Resistance to UV light, heat and pollutants—for most natural and synthetic fibres, especiallypolyamide fibres14. Thermal conductivity (hot or cold, thermal comfort)—all natural and synthetic fibres

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Factors for Chemical Finishes?

1. The type of textile (fiber composition of the fabric and its construction)2. The performance requirements (extent of effect and durability)3. The economics of the formulation4. Availability of machinery and associated process restrictions5. Procedure requirements6. Environmental consideration7. Compatibility and interactions of finishing components.

Chemical Finishes

1. Low-cost product and process

2. Stable during storage and application in terms of pH, temperature and

mechanical stress

3. Compatible with other finishes

4. Adaptation to customer requirement and substrate variation

5. Suitable for all kind of fibers and all textile forms such as yarn,

woven or knit fabric, nonwovens, etc.

6. Satisfactory stability during washing and dry

cleaning

7. Should not hamper important textile

qualities

8. On application should be distributed evenly on

the fabric and fibre surface

9. No yellowing of white goods or colour change

of dyed goods.

10. Easy correction of finishing faults

11. Nontoxic and ecofriendly

12. No release of volatile organic

compounds13. Biodegradable

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Dry Chemical Finishes

Using gas instead of liquid for chemical finishing of textilesExamples:1- using chlorin gas (Cl2) or ozone (O3) for oxidizing, bleaching, ..2- Using plasma (i.e., excited gas) for:• Materials Cleaning• Activation of materials• Etching materials• Coating of materials

https://www.thierry-corp.com/plasma-systems

Plasma

https://www.youtube.com/watch?v=7CUC1HPyydA

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Atmospheric Plasma Chamber

Photograph (left) and the scheme (right) of the DCSBD in the roll-to-roll arrangement. 1 -power meter, 2-AC-HV generator, 3-rotor-speed control, 4-cooling oil input and output, 5-reactor chamber for DCSBD plasma, 6-sample of paper, 7-rotor, 8-adjustable holder of DCSBD plasma system, 9-DCSBD plasma system, 10-HV-power inlet.

https://aip.scitation.org/doi/full/10.1063/1.5124149

Plasma Treatment for Surface Modification

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Textile Finishingwith Plasma Treatment

1. Antifelting/shrink resistance of woollen fabrics2. Hydrophilicity enhancement for improving wetting and dyeing3. Hydrophobic enhancement of water and oil-repellent textiles4. Removal of the surface hairiness in yarn5. Antibacterial finish6. Room-temperature sterilization of medical textiles7. Flame-retardant coating using monomer vapor (halogen and/or phosphorus) in combinationwith nitrogen and/or silicone8. Silicone coating of airbag fabrics using cross-linked silicones (polyorganosiloxanes)9. Durable antistatic properties using PU-resin and plasma processing10. Shrink resistance of animal hair textiles using urethane-based resin and plasma processing11. Electroconductivity of textile yarns surface. The plasma treatment improves wettability andsoil release properties of polyester.

https://www.plasma.com/en/plasma-in-textile-technology/Please review:

•Textile pretreatment•Dyeing•Coating / Printing•Finishing

Self Study

• Title: A review of low-temperature plasma treatment of textile materials

• Source:https://link.springer.com/content/pdf/10.1007/s10853-015-9152-4.pdf

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Textile Coating

• Adding functional properties on textile fabrics by applying a coating formulation containing functional chemicals and binder

Typical applications• Clothing: artificial leather, outdoor wear, waterproof dress/tent• Home Furnishings: Upholstery, carpet backing

• Medical: plaster, medical gloves, implants, hygiene products

• Industrial textiles : transmission belts, conveyor belts or barrier materials

• Protective wear: including aprons, chemical boiler suits, space suits

Applying Chemical Finish and Coating

• Exhaustion (batchwise in winch, jigger, or jet dyeing machines)

• Continuous DirectTransferSprayExtrusionFoamed

Next Slides

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Winch dyeing machine

L:R = 1:15-1-40 L:R = liquor to good ratio

Jigger dyeing machine

L:R = 1:5

L:R = liquor to good ratio

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Jet dyeing machine

L:R = 1:2 to 1:5

L:R = liquor to good ratio

knife-over-roll coating

https://www.sciencedirect.com/science/article/abs/pii/S0001868618303129

Coating formulation

Fixation

Fabric layer

Coatingknife/blade

Direct coating: spread the coating material on the textile with a fixed knife

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Applying Chemical Finishmost popular : pad-cure

P

Impregnation bath

Heat Fixation

Calendering

Fabric layer

https://www.sciencedirect.com/science/article/abs/pii/S0001868618303129

Padding Mangles

• For finishing, most fabrics at speeds of up to 50 m/min, single-dip and single-squeeze processes are sufficient. For higher speeds (e.g., 120 m/min) or for heavy fabrics, the double-dip and double-squeeze process using a three-bowl padding mangle is preferred.

• Depending on the pressure applied, higher diameter rollers have a larger area of contact between two rollers.

Common width of rollers 1.5-2.5 mDiameter of rollers 0.3-0-4 m

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Padding mangle coating

• The rubber surface of the rollers should be resistance against the finishing formulation.

• The rollers should be washed thoroughly after each finishing. The volume of the pad box should be as small as practicable. the rollers should be covered during storage and protected from sunlight, moisture, excessive heat or cold.

• The pressure should be applied only when the rollers are in use.

Why?

Why?

Why?

Tailing effect

The volume of the pad box should be as small as practicable and the concentration of finishing agent should be constant in order to avoid a tailing effect, a problem that arises from the preferential pickup of finishing agents by the fabric, resulting in a variation in composition of the liquor as the run continues. The finish liquor may be fed to the trough with the help of a pump through a perforated pipe running across the back of the box. The perforations are pointed down and are away from the fabric.

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Question?

• How can we reduce the solution pick up by the fabric in the padding-mangle process?

P

Impregnation bath

Calendering

Fabric layer

Common pick up 80%

Loop-transfer system with three-bowl padding mangle.troughless padding mangle.

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Remove water from fabric

• Vacuum or suction extractor• Hot cylinder• Stenter

Energy intensive processes!

Textile wet processing is highly energy intensive. Virtually all of the thermal energyconsumed in textile wet processing is used for either the heating or evaporation of water.

Drying and Curing

• The water dispersed in a textile material by a chemical–physical process is generally eliminated by the action of hot air, which makes the water evaporate.

The drying process can be carried out by:● Heat convection● Contact with heated metal surfaces● Infrared radiation● Microwaves or high-frequency waves● Combustion

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Drying

• After the application of finishes, water is evaporated to make the fabric dry.

• Drying is a high energy-consuming step and significantly affects the cost of finishing.

• Choosing the right equipment to handle the fabric is an important matter when one is trying to create specific fabric properties.

Energy consumption

• 1 Kg fabric after padding (pickup 80%) contain 800 g of waterThe approximate energy for removing water?Total energy= m×cp × (100-T)+m ×hlv

0.8 Kg x 4200 J⋅kg−1⋅K−1 x (100-21 K) + 0.8 Kg x 2260000 J⋅kg−1

2073440 J = 0.57 kWh

cp : specific heat capacity of waterHlv : latent heat of evaporationthe amount of energy (enthalpy) that must be added to a liquid substance to

transform a quantity of that substance into a gas

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Energy consumption!

• The total energy consumption for preparing 1Kg of finished fabric may reach up to 16.5 kWh ! Why is so high?

• What would be the cost of production in Finland compared with that in China?

Discussion !

Countries Price of Electricity ( €/ kWh)

Germany 0.32

Finland 0.18

USA 0.13

China 0.08

Iran 0.009

https://www.statista.com/statistics/263492/electricity-prices-in-selected-countries/

the main producer of textiles

Long process

Rawmaterials

Textiledresses

cleaning,carding, combing, roving, plying, spinning, twisting

TextileTechnology

SewingCloth making

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Hot drying cylinder

The type of dryer used will affect fabric properties. The cylinder dryer, in which the fabric is passed over hot metallic cylinders, was once very popular. But some fabrics will develop a surface sheen when they come in contact with heated surfaces, and some will shrink unless the fabric is restrained. Tension can cause the fabric to become stiff. The main limitation of a conventional cylinder dryer is that there is no control of fabric width.

Hot Drying Cylinders

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Stenters

• Stenters are the most expensive and most important machines in a textile factory! However, the stenter is the only drying machine that provides adjustment and control of fabric width during drying. In addition to drying, the stenter performs several other functions, namely:

1. Heat setting of fabrics made of synthetic fibers and blends.2. Applying and fixation of several finishing agents.3. Imparting a particular mechanical finish affecting appearance and feel, commonly known as stenter finish.

Stenter

https://www.youtube.com/watch?v=KnxwFTVPn2c

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Heat setting

• Compaction of the thermoplastic structure occurs when the fibers are raised to near their softening point. At a sufficiently high temperature, the fibers shrink and contract and achieve a stable structure, causing compaction of the textile structure.

Heat Setting by Stenter

• Stenters are widely used for stretching, drying, heat-setting and finishing of fabrics. The stenter frame is usually 25-30 m long and 1-3 m wide. The speed ranges from 10-45 m/min with a maximum setting time in the setting zone 30 sec at temperature ranging from 175 to 250 C depending upon the thickness and type of the material.

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Stenter

Side View of a Stenter

Stenter unit

1 Gas burner2 hot air compartment3 hot air blower4 upper nozzle5 lower nozzle6 returned air7 fresh air nozzle8 air filter9 operator door10 maintenance door11 exhaustion

Cross-Section View

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Question?

• What are the important parameters on drying a fabric with a stenter?

The speed of stenter

• The speed of stenter ranges from 10 m/min for heavyweight to 100 m/min for lightweight fabrics. The actual speed also depends on the particular operation (e.g., drying, heat setting, weft stretching or finishing) being carried out. The higher the speed, the more vital the need for a good entry system to ensure that the fabric is properly centered, and the edges are fed onto the pins at the correct speed.

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Width adjustment

• Two endless chains equipped with either clips or pins grasp the selvedges and move in synchrony, carrying the fabric between them. The width between the two chains can be automatically adjusted by means of a motor-driven screw.

• For example, the width may be narrow at the entry point and be pulled out at a subsequent section to make it wider, or the final width may be set narrower and allowed to shrink.

Modern Stenters

• Some modern frames are equipped with fabric temperature sensors located along the length of the frame as a better way of controlling the process. By knowing the point within the frame when the fabric is dry, the frame could be programmed to control the speed, regulate temperature in various compartments, curing temperature, and duration.

• A major trend is to (a) provide improved and more consistent textile finishing quality, (b) increase productivity while reducing overhead costs

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What did you learn?

1. Finishing Classification and examples2. Mechanical and Chemical Finishing3. Plasma Treatment 4. Applying Functional Chemicals and Coating5. Drying methods including stenters

Chapter 1

https://www.sciencedirect.com/book/9780081006467/principles-of-textile-finishing

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