Non-Woven Finishes
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- Created on Sunday, 05 November 2017 21:56
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- Published on Sunday, 05 November 2017 21:56.
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- Non-Woven Finishes writer Faik KeserPosted by %PM, 05% 828% 2017 21%:%Nov in Non Woven Surfaces Read 2651 times
Nonwovens often require finishing processes in order to give the products the desired usage properties. However, there are also non-woven surfaces that can be used without finishing. Finishing processes applied to non-woven surfaces;
Pretreatment
dye-print
Finishing processes
It is divided into 3. In addition, conversion processes are applied if desired.
PRE-FINISHING PROCESSES
At the beginning of the textile finishing, as a preparation for other finishing processes, all of the processes performed to remove the disturbing foreign substances in the product (in and on the fibers) and to improve the appearance of the product are called pre-treatment processes.. Pre-treatment, also known as preparation, is the preparation stage for the dyeing and finishing processes that the products will see later. In these processes, a wide variety of chemicals are used to give the product its properties. Depending on the type of material, various pre-treatment processes such as bleaching, desizing, mercerization, fixation, etc. can be applied.
A-Fixing
The fixation process is a pre-treatment process applied to wool, acetate, polyester and polyamide fabrics. The purpose of the fixation process; is to make the textile surface permanent by preserving its shape.. In the fixation process with hot air, steam or water, hot air is preferred most intensely.
B- Incineration
The purpose of the incineration process; is to prepare the incoming fabric for other processes by burning it. The fibers on the raw fabric give the fabric an undesirable feature. These fibers make the fabric mart and cause pilling on the fabric. Since the ends are exposed, they are not painted and an error called brittleness occurs. In addition, these fibers prevent the pattern from being clear by entering between the templates during the printing process. In order to eliminate the defects caused by all these fiber extensions, the fiber ends are burned. After the burning process, the fabric provides brightness, color vibrancy and soft touch. In addition, pilling is prevented and air permeability is increased (Fibers that have come to the surface from the fabric are removed on the filter fabric obtained from staple fibers by surface burning. A hot metal strip or gas flame can be used for this process. After the process, the filter fabric is contacted with a wet surface. A smooth surface is obtained thanks to surface burning.
DYE-PRINTING
Non-woven surfaces to be used for decorative purposes such as floor coverings, beds or tablecloths can be subjected to plain or patterned coloring processes. Factors to be considered in painting; are parameters such as purity, penetration, and even distribution on the fabric. Along with these parameters, it is also important that it is economical and does not harm the environment. The production method of the fiber material used here plays no role. They can be processed in the form of hank, tops, yarn, strip or fabric. Man-made fibers can be dyed while the yarn is directly melted during manufacture. Different dyestuffs suitable for fiber properties are used for different fibers. The painting of nonwovens can be done at every stage, starting from polymer to cheesecloth form.
Multicolored patterns can be obtained by working with colored threads or by printing on fabric with dyestuffs. The purpose of the printing process is to create beautiful motifs, colorful attractive decors and patterns on the fabric. Particular attention should be paid to the brightness of the colors, smooth and sharp pattern lines, as well as high color fastness. The increasing use of nonwovens, especially in the furniture industry, increases the importance of printing processes. The most used printing methods are rotation and filmdruck. are pressures. The printing process is generally similar to the classical knitting and woven printing processes. Pigment printing is used a lot. Binders used according to the recipe are very important as they facilitate the holding of the structure together. This effect is especially evident on spunbond nonwoven surfaces. Printing processes are continued with fixation classically. Pigment printing is particularly suitable for the printing of nonwovens. Transfer printing is also preferred, especially on polyester non-woven surfaces. The basis of the method is the sublimation transfer of selected disperse dyestuffs with a very low sublimation coefficient on the paper to the nonwoven surface at high temperature.
FINISHING PROCESSES
A-Mechanical Finishing Processes
lifting
Lifting; It is applied for surface properties such as smoothness or patterning of nonwovens.
All processes are continuous and are made by passing them through one or more pressurized cylinders.
The effect is achieved by passing the fabric between heated, rotating rollers whose speed and pressure can be varied.
The number of calender cylinders varies between 2-7. The construction of the rollers can range from hardened chrome plated steel to elastic thermoplastic rollers. Their surface can be smooth or engraved.
With calendering;
- The product surface is made smooth,
- The brightness of the product is increased,
- The threads that make up the product are zoomed in,
- Air permeability is reduced,
- The attitude of the product is improved,
- The surface is patterned with printing calender,
- The webs are fixed.
raising
In the raising process, thin and soft piles are created on one or both sides of the nonwoven fabric by using a thin steel comb.
Afterwards, a cutting process is applied so that the piles can be of the same length. It is used to obtain a fur-like effect by removing the fibers on the surface of the product.
With embossing, a desired pattern or mold is passed onto cheesecloth by means of pressure rollers.
lamination
Lamination; It is a combination of two materials. The product contains the characteristic features of the two materials combined.
In other words, if only the warp strength is good in one component and the weft strength of the other is good, both weft and warp strength will be good in the resulting product.
The product produced by lamination can be solid from both components, and the way to minimize this is to choose the most suitable lamination method and adhesive.
The criterion for choosing an adhesive is to create the strongest bond with the least amount of adhesive.
The most common problem of laminated fabrics is cracks, which limit the lamination to bend like a spring, as neither one or both materials being joined has sufficient flexibility.
Cracking is caused by excessive use of adhesives or excessive use of foam in flame lamination.
The suitability of the fabric for lamination is important; The fabric should be very flexible, have good handle and drape.
Usually a third material is used as the adhesive, but sometimes in flame lamination of polyurethane foam, a bonded material can act as self-adhesive.
B-Chemical Finishing Processes
water repellency
When a substance comes into contact with water, its wetting or repulsion is closely related to boundary surface forces.
Since the surface tension of the fibers in the fabric is increased against water with the water repellent finishing process, the water coming to the surface is not absorbed by the fabric and water droplets remain on the fabric surface in the form of globules.
Water repellency is an important feature, especially in air filtration applications.
Water repellency finishing; It prevents the products from decomposing and gaining a wet structure when exposed to water.
Antibacterial
In antibacterial finishing processes, the activities of microorganisms are stopped by transferring antibacterial substances to the textile product with the help of one of the methods of shrinkage, impregnation, vacuum application, maximum liquor application, transfer, spraying, foam application and coating.
It is a chemical finishing process that protects textile fibers against all kinds of microorganisms, stops the growth and reproduction of microorganisms on textile or human skin or kills them.
It is especially applied to non-woven fabrics used in places such as hospitals, nursing homes and kindergartens where collective life is in question.
Power Flammability
Combustion occurs when the substance combines with heat and oxygen.
By applying the flame retardant process, the products can be made non-flammable..
The purpose of applying flame retardant treatment to fabrics is to ensure that the products do not burn by being protective in case of fire.
Flame retardancy treatment, which varies according to the fiber structure, type, weight, weaving structures, fiber combinations, resistance to washing or dry cleaning of the product applied; It can be applied by scarf, spray, coating or foam method.
Application methods vary according to the textile material to be used or the areas of use.
The use of flame retardant materials as a scarf rather than a coating increases their efficiency because the chemical performs best when it penetrates into the fabric.
The water-insoluble materials in the flame retardant materials used as coating prevent the penetration of the flame-retardant chemicals into the fabric. In this case, a decrease in efficiency is observed in thick fabrics.
antistatic
Clothes can stick to the body as a result of static electricity.
Despite their tendency to increase static electricity, natural fibers maintain their importance in the textile industry.
Products produced from synthetic fibers may also experience static electricity and dangerous discharge problems may occur.
This risk is most evident in the applications of fabric bag filters used to collect dust from flue gas.
To prevent this, the system must be well grounded, which can only be possible if the filter structure has high electrical conductivity.
Therefore, electrically conductive anti-static fabrics are used to control the static charge in the product.
Some of these anti-static fabrics have metal fibers inside the fabric structure, while others have a conductive coating on the fabric structure.
However, metal fibers that can be added to the textile structure (flexibility, fineness, etc.) are quite expensive and therefore costly.
Conductive metal or polymer coatings can be obtained by methods such as electrochemical, chemical and oxidative polymerization or magnetic sputtering.
However, static electricity can be prevented by adding a moisture-retaining copolymer substance into the polymer drawn from the nozzles.
Conversion operations
The conversion process, which takes place before the product reaches the consumer, is also included in the finishing processes.
In this process, non-woven products are made ready for sale by going through stages such as cutting, folding, sewing, re-wrapping, packaging, sterilizing if necessary, treating with a lotion in the width and length desired by the buyer.
Non-woven fabrics prepared in this way are encountered in many areas in daily life.
The following are the finishing processes most commonly applied to non-woven fabrics;
Antistatic finishing is applied to prevent or reduce static electricity in textile products.
Static electricity is more common in synthetic fibers due to their hydrophobic structure.
Static electricity can be prevented by increasing the humidity in the environment during the production phase of this fiber or by adding a moisture-retaining copolymer substance into the polymer drawn from the nozzles.
Another finishing process applied to non-woven fabrics is water repellency finishing.
The basis of this process is to form a very thin hydrophobic membrane on the fibers or threads of the textile product.
When a substance comes into contact with water, it gets wet or repels water is related to boundary surface forces.
By using different chemicals, the fabric can be given a water-repellent feature that is resistant to washing and not resistant to washing.
The water repellency finishing process is generally applied to the fabrics used in tents, awnings and tarpaulins.
Antibacterial finishing process; It is a chemical finishing process that protects textile fibers against all kinds of microorganisms, stops the growth and reproduction of microorganisms on textile or human skin or kills them.
It is especially applied to non-woven fabrics used in places such as hospitals, nursing homes and kindergartens where collective life is in question.
The lamination process is to glue and iron different types of fabrics together.
Application areas of lamination and bonding products include composites, ultrafiltration products, cleaning products, packaging materials and sterile bandages.
Artificial leather is formed by absorbing and applying solutions containing polyurethane to non-woven fabrics. In other words, artificial leather appearance is obtained by precipitation of polyurethane in non-woven products.
Artificial suede is produced by sandblasting this polyurethane surface or by brushing non-woven fabrics produced from very fine fiber and impregnated with chemical materials.